Note: Descriptions are shown in the official language in which they were submitted.
~ ` - 10~8149
.
Various methods are known for producing ima~es or
dupiicates of images. The imaging materials used are, in certain
cases, particular inorganic compounds and, in other cases,
particular organic compounds. Some of these heretofore
known methods employ mixtures of inorganic compounds such as
silver halide, or silver salts or copper salts or other
metal salts, with various types of organic compounds as
sensitizers, in admixture in a film-forming carrier.
The present invention is concerned with a new i~aging
system which employs organo-tellurium compounds, that is,
image-forming organo-tellurium compounds in which tellurium
is linked directly to at least one carbon atom of an organo
radical of the organo-tellurium compounds or is complexed
with an aromatic amine, said image-forming organo-tellurium
compound being of one structure having one detectable
characteristic and which i~ capable of undergoing a change3
such as a chemical change, in response to the application of
; energy to produce a material of different structure having
' another detectable characteristic. The organo-tellurium
',~ 20 compounds may take many forms, as will be pointed out below.
'' Particularly advantageous are those which contain at least
one carbonyl group in an organic radical or organic radicals
of the organo-tellurium compounds. In others of said
organo-tellurium compounds, halogen is present in the
molecules, and, especially, the halogen is attached directly
to a tellurium atom. In still others of said organo-tellurium
compounds, there is at least one carbonyl group present in
an organo radical and, in addition, halogen is present
attached directly
: ~ .
::
, . ,
~ -2-
.~
'
'
, , ~ . , ~
--" 10tj81~9
:
to a telluriu~ atom. In others of said organo~tellurium com-
pounds, no carbonyl groups are present in an organo radical,
and in such and others of said organo-tellurium compounds no
halogen is present. Numerous embodiments of the image-forming
organo-tellurium compounds are disclosed hereafter.
In the particularly important embodiments of the inven-
tion, the aforesaid image-forming or imaging organo-tellurium
compounds are incorporated into a matrix together with a
phot~sensitizer (hereafter, for convenience, called "sensiti-
zer",) all as is hereafter described in detail. ~he resulting
; combination of materials is formed into a thin film or layer
which i8 capable of producing a latent image when subjected
to imaging energy as, for instance, actinic radiation or
electro~agnetic radiation. The resulting latent image may
then readily be developed into an image of excellent contrast
by wet development procedures, or by dry development proce-
, ~ , .
; dures as, for instance, by subjection to a source of develop-
ing energy, generally in the form of or including heat energy.
Accordingly, the invention provides novel teachings and
novel articles or compositions for producing records of re-
trievable information, for instance images and duplicates of
exi~ting images, which are predicated on a layer which com-
prises image-forming or imaging organo-tellurium compounds,
which are of one structure and have one detectable character-
istic and which are capable of undergoing a change in response
to the application of imaging energy to produce a material of
different structure, having another detectable characteristic,
and which difference in detectable characteristics may be
.
~3~
bm/ ~ ~
; , ~ .
~ ~068~9
detected by:any suitable detection ~eans ox read out ~eans.
The material having a different structure and different
detectable characteristics, resulting from the imaging step, `
will sometimes hereinafter be called the image former.
As will be discussed in further detall below, i~ has been
found that organo-tellurium compounds possess certain proper-
ties which adapt them especially for use in imaging processes.
Notable is the fact that, as a result of the imaging and devel- .
opment steps, described hereafter, metallic tellurium is de- :
posited from the organo-tellurium compounds. WhiIe tellurium
i~ not actually a metal, it does have some metallic character-
istics and acts as a metal in some respects~ and in some
;; :
instances the deposited tellurium is referred to herein as
~` , metallic~.tellurium. Tellurium is chain forming in character
: and it is generally deposited from the organo-tellurium com-
: pounds in chain form, which preferably includes thin needles,
which are capable of rapid nucleation and growth of crysta.l-
lites, which crystallites grow as chains and largely or mainly
.~ as needles. Such chains or needles are opaque and are
characterized by excellent li~ht-scattering properties, and
. ......... they produce optical densities which are observed after thermal :
or other development; and such effects as may involve oxide
. formation are substantially restricted to surface effects as
: distlnguished from causiDg degradation through the bodies of
, said chains or needles.
,~ As noted above, among the imaging organo-tellurium.com-
.. pounds utilized in the practice of the pre~ent invention are
those which comprise organic compounds which contain in the
molecules an organo radical, tellurium and halogen attached
directly to the tellurium atom, there being at least one car~
'
: -4-
~ , . .
bm/ ~
.
.
j;~, . - .
81~9
~onyl group in an oxgano radical, Ce~tain of them are adducts
of tellurium halides~ notably tellurium tetrachloride~ with
organic compounds, notably ketones or similar chromophores,
containing at least one carbonyl group in the organic com- '
pound. This particular group of imaging compounds may, thus,
be considered or characterized as organo-tellurium compounds
or adducts containing halogen, namely, chlorine, bromine,
iodine, and fluorine, attached directly to the tellurium atom.
Most of this particular group of said imaging compounds have
two carbonyl-containing organo radicals and some ~f ~hem
contain three carbonyl-containing organo radicals. Those
which are particularly useful in the practice of the present
invention have chlorine as the halogen but, in certain cases,
although generally less satisfactory, other halogens can be
present. The imaging compounds should be selected to be
soluble or homogeneously dispersible in any particular matrix
; material which may be utilized, as i~ described hereafter.
Many of this group of imaging organo-tellurium compounds may
be represented by the formula
Rx-Te-Haly
where R is an organo radical containing at least one carbonyl
group, Hal is halogen, especially chlorine, x is 1, 2 or 3 and
x plus y equal ~, sub;ect to the proviso that y is 2 when x
is 2 and y is 3 when x is 1, and Te is linked directly to
carbon in an organo radical. The R radical can be aliphatic,
cycloaliphatic or aromatic (mononuclear or dinuclear), ~
' ::
bm
. , ' . , ' ., , ' ,:
~ o~
`or a combination thereof and can contain one or ~o~e hetero
atoms in the chain or rings. It can be unsu~stituted or
substituted, illustrative of such substituents being Cl-C6
alkyl, corresponding oxyalkyl radicals, acetyl, nitro, C N,
Cl, Br, F, etc. Generally speaking, the aforesaid organo-
tellurium imaging compounds which contaln a trihalide group
as, for instance, acetophenone tellurium trichloride, tend to
have relatively low melting poin~s (~70- ~80C), and are more
; hygroscopic and less stable than Ithose generally similar com-
pound8 containing two halogen atoms and, therefore, such
trihalides are less desirable for use in the practice of the
present invention.
A more limited class of this particular group of imaging
organo-tellurium compounds may be represented by the formula
.
(Ar-CO-CH2)2 Te Hal2
..
where Ar is an aromatic hydrocarbon radical, which may be sub-
stituted or unsubstituted, as indicated above, and Hal is hal-
~ .
i ogen, especially chlorine. This group of compounds~ partic-
; 20 ularly where Hal is chlorine, represents especially advanta-
geous embodiments of the invention, with respect to the imag-
ing organo-tellurium compounds which are used in the practice
of the present invention.
Among the imaging organo-tellurium compounds which do not
contain a carbonyl group in an organo radical are tellurium
tetrahalide adducts
.
--6--
'
bm/-~
10ti8~3
of aromatic amines in ~hich nitrogen linked o~ attached di-
rectly or indirectly to the aromatic radical is substituted
by alkyls each containing from 1 to 4 carbon atoms. Numbers ~ :
of illustrative examples of such compounds are disclosed here-
after. -:
Still another group of imaging organo-tellurium compounds
which do not contain a carbonyl group in an organo radical but
in which tellurium is linked directly to carbon are compounds
which may be considered or characterized as tellurium tetrahal-
ide adducts of ethylenic or of acetylenic hydrocarbons. These
compounds are generally conveniently produced by reacting 1 to
2 moles, particularly 2 moles, of the ethylenic or acetylenic
hydrocarbon with 1 mole of tellurium tetrahalide, especially
preferred for such use being TeC14. Certain of such compounds
can be represented by the formula
.~ ' ' .
Hal
Hal R Te- R ----Hal
Hal
and
: 20 .:
(Hal-R)m Te Haln
where R and Rl are each the residue of an ethylenic hydro- ~
carbon, for instance, an alkene or a cycloalkene, Hal is -~ :
chlorine, bromine or iodine, especially chlorine, m is 1 to
2 and n is 1 to 3 with the proviso that the sum of m and n is
4. Illustrative of the ethylenic and acetylenic hydrocarbons
,: '
~7~ -
' ' '~
.` bm/'`.. ,_.~
.: .
lO~;Bl~9
with can be adducted with tell~iu~ tetFahalides to produce
, such imaging organo-~tellurium compounds are propylene; butene-
.. . . .
l; isobutylene; butene-2; 2,3-dimethyl~2~butene; 3,3~dimethyl- -
l-butene; 2,4-dimethyl-1-pentene; 4,4-dimethyl-l-pentene; 2,5-
dimethyl-3-hexene; dipentene; l,l-diphenylethylene; l-hep~ene;
l-hexene; 2-methyl-l-hexene; 3-methyl-1-hexene; 4-methyl-1-
hexene; 2-ethyl-l-hexene; 2-isopropyl-1-hexene; 2-methyl-1-
pentene; 2-methyl-2-pentene; 2-ethyl-2-pentene; 3-methyl-1-
pentene; piperylene; vinylcyclohexene; vinylcyclopentene;
2-vinyl naphthalene; 1,2,4-trivinylcyclohexene; 4-methyl-1-
cyclohexene; 3-methyl-1-cyclohexene; l-methyl-l-cyclohexene;
l-methyl-l-cyclopentene; cycloheptene; cyclopentene; cyclo-
hexene; 4,4-dimethyl-l-cyclohexene; 2-methylbutene-1, 3-methyl-
butene-l and l-octene; lo~er alkyl and lower alkoxy deriva~
tives of variou~ of the alkenes Ruch as cyclohexene; l-pentyne;
2-pentyne; l-hexyne and 3 methyl-l-butyne.
The preparation of various of said organo-tellurium com-
pounds by adducting ethylenic or acetylenic hydrocarbons or
alkenes or alkynes with tellurium tetrahalides is disclosed
2~ in such references as the following: M. DeMoura Campos and
;
N. Petragnani, Tetrahedron, 18,521 tl962); M. Ogawa, Bull,
Chem. Soc. Japan, 41,3031 (1968); H. Funk and W. Wei86, J.
Prakt. Chem. 1,33 (1954); and W. V. Parrar and J. M. Gulland,
J. Chem. Soc., 11 (1945).
Still others of said imaging organo-tellurium compounds
possess in their molecules neither a carbonyl group in an
organo radical, nor halogen, nor halogen linked directly to
tellurium, as will be seen hereafter.
,
~ bm/~)
8 ~ ~9
~ The followlng are illustrative examples of the foregoing
imaging materials;
: (1) (C6H5COCH2)2TeCl2 ~
(2) (p-C2H50C6H4COCH2)2TeClz : ~ .
(3) (p-CH3C6H4COCHz)2Tecl2
(4) (p-CNC6H4COCH2)2TeCl2
(5) (CH3COC6H4COCH2)2TeClz
(6) (02NC6H4COCH2)2TeCl2
: (7) (cloH7cocH2)2Tecl2
(8) p-CH30C6H4Te(Cl2)CH2COC6H3
C-CH2-Te-CH2-C - Q
O Cl O
(10) (CH3COCH2)2TeCl2
(11) ((CH3)3CCOCHz)2Tecl2
. (12) (C2H5COCHCH3)TeCl3
. (13) (C6H~COCHCOCH3)TeCl3
! (14) (C 6 H,COCH 2 ~ TeCl3
:; (15) (o-CH30C6H4COCH2)2TeCl2 `~
- (16)
COCH~ 2TeCl
, (17~ ( C ~ COC~ TeCl2
3 CH3 2
. (18) (p-F C6H4COCH2)2TeCl2
. .
,,~
. 30 -:-:
. :
j l /\~ `3~ - 9-
~" '
- :
lV~8:~9
(19) ( ~ CO ~ leCl~
(20) ( ~ CO ~ TeCl~
S~ ~0~) 2TeCl~
(22) ~ CDC ~ TeCl~
; (23) ( 0 ~ ) 2TeCl2
O O O
:
(24) C ~ _ CN-CH-CO~ ,TeCl,
(25) ~ ~ C-CH ~ 0 3 TeCl2
:
(26) (C2H~-C-CH2-f-C2H,)2TeCl2
O O
. (27) (C3H~-C-CH2-C-C3H~)2TeBr2
O O
(28) (CH 3 -C-CH 2 -C-CH3)2T e C 1 2
Il 11
O O
TeCl:
(30) ~ CHCl `\
H2C CHz\
TeCl2
H2C\ / CH2
\ ,CH2 2
n-
,
':
10~ '3
~31) ¦ ~CH2-CN~
(3Z) ~C}~
=O . ~,
CH2 2
~ T e C 13 ~
:.' 11 1' . :
,: O O
(34) :
C CH2 T C 2 ~
'' 1~
., e
: (36) (c6~s)3c-Te3cll3
(373 ~ 0 ~
(38) ((CH3)2N C6H,)2TeCl4
(39) ((C2H~)2N C6Hs)2Tecl4
(40) ((C3H~)2N C6Ha)2Tecl4
(41)~ H3) 2N C6--~
~ ¦ ) TeCl4
: ~ 3 ~
'.
' -
. 30 ~
: ' ~
..
.
_~- (42) ~ H3
N~ c6H5 ) TeCl4
2H~ ~ 2
(43) (C6H,N2C6H4N(CH3) 2) 2TeC14
(44) (C6H5NzC6H4 (c2H~)~)2Tecl4
: (45) ~ CH ~
,~ ~ (c6H5N2c6H4N ~ )TeCl4
(46) ((CH3)2N C6H5) 2 TeC12Br2
~ (47) ((CH3)2N c6H~)2TeBr4
;~ (48) (C6H,N2C6H4N (CH3) 2) 2TeClzBr
(49) (C6H,CH2N(CH~) 2) 2TeC14
; (50) ~ H, CH C6 ~
. ~ ¦ )TeCl4
~ N(CH3 ~
(51) ((CH3)2NC6H5)2TeI4
(52) ((c2H~)2Nc6H~)TeF4
(53~ ~ Cl ~1
(54) . fl
Cl-CH2-CH2.-Te-CH2-CH2-Cl
Cl
'-~ , .
~ 12-
': ' ~ .
:: ~ - : '.` `
~06~
~Q\ T e C l 3 . : .
Cl
(56) (C6H5COCHzCOCHCOC6Hy) 2TeCl2 ~ .
(57) Cl / Cl
~Te~
~ ' - ,:,
(58) (p-Br-C6E4COCH2)2TeCl2 :
(59) (p-I-c6H4cocH2)2Tecl2
; ~60) ((CHg)2NC6H4COC6H4N (CH3))2TeCl4 . ~-
(61) ((C3H,)2NC6H4COC6H4N(C3H,))2TeCl4
:: . .. .
~ (62) ((C2H5~2NC6H4COC6U4N (C2H~) )2TeCl4
.,., ~ ',.
.' '~ . .
, I , ..
i"', ~ ' .
.:'~', . :
. ~'',
.: .
. . :.
~ 20
.. ~'` ' ~ ,.
: , ' ' '
',~'~ ' ' ' "
: '
.: ......................................................................... :
. ' ~' 30 .
,:
.;~ ~, .
j l/ ~ 13-
'`'.:
.
' ' ' . ' ' ' ' .
10~i8~L49
(63) Cl
Cl O
Rl R2
wherein Rl and R2 are Cl-C4 alkyl, or cycloalkyl such as
cyclohexyl.
: (64) Cl C2H,
~C_ 1 TeCl3
(65)
0
;, CH-CH2-CH2-Te-CH2-CH-CH2
0/ 11 1 C~0
~ \~
(66) CH2
H2f fH2
H2C CH2
:. T <
Cl Cl
The use of the.foregoing examples of illustrative compounds
in the form of their corresponding bromides and iodides, is
also encompassed within the scope of the present invention,
the chlorides, however, at least in most cases being distinctly
~ preferred.
,:
~ .
.
jl/`.,~. -14-
: . ' ~ . . ~ :
:
10681~9
;. :~ ' "
yarious o~ the f,oregoing compounds are per se known com-
pounds although thelr utillty for the purposes of the present
invention has not heretofore been known or suggested. Others
; of said compounds, so far as we are aware, have not heretofore
be~n known or prepared.
Compounds exemplified by Example (1), ~or instance, can
conveniently be prepared by the procedures disclosed by Rust
(Ber. 1897, 80,2833~, and G. T. Morgan and 0. C. Elvins, J. C. S.
1925, 2625, or modifications thereof. Thus the compound of
Example (1), Bis(acetophenone) tellurium dichloride, is desir-
: .
ably prepared by the following procedure:
Acetophenone (5.0 g), and tellurium tetrachloride (5.6 g)
in benzene (60ml? and chloroform (40 ml) ane stirred at room
temperature for 5 hours. At the end of the reaction time the
; solvent is removed by rotary evaporation with evolution of
HCl. The mixture is concentrated to a volume of 20 ml, then
methylene chloride (5ml) is added. Addition of diethyl ether
(50 ml) to the mixture and standing gives a first crop of
whi~e, crystalline needles m.p. 188-190C.
`~ 20 Compounds exemplified, for instance9 by Example (14) are
desirably prepared by the following procedure:
Acetophenone (2.4 g, 2 x 10 moles) and tellurium tetra-
chloride (5.4 g, 2 x 10 moles) in chloroform (50 ml) are
stirred for 1 hour. When 70% of the solvent is removed, yel-
low hygroscopic prisms are formed, having a melting point of
75-78C.
~ .
' .
''`', ' '
.
, , .
-15-
'
, . bm C!~
"- 10~ ,9
; Additional im~ging ~aterials of the ~rst group~ which
can be used in accordance with the present invention are sO-
called "yellow" compounds or adducts resulting from reacting
ketones with tellurium halides, notably tellurium tetrachlo-
ride, an example of which is the following:
- (63) "Yellow" compound from Bis(acetophenone)
tellurium dichloride synthesis
Acetophenone (5.0 8) and tellurium tetrachloride (5.6 g)
in 25 ml CHC13 are stlrred at room temperature. After 70
hours the solvent is removed and a viscous greenish yellow
oil remains. The oil is dissolved in methylene chloride (10
ml) and diethyl ether (50 ml). On standing, orange prisms
come out. Yield 3.3 g, m.p. 132-134C; I.R. (KBr3 1600 cm
1590. Elemental analysis observed; C = 42.22, 42.24; H ~ 3.27,
2.98; Te - 15.30, Cl ' 23.50. The reaction can be accelerated
by refluxing the above reaction mixture. However, in such
case, distinctly impure products, including Bis(acetophenone)
tellurium dichloride, are formed.
It will be noted that this "yellow" compound appears to
be reIated to the previously described Bis(acetophenone)
; tellurium dichloride. However, it is a distinctly different
material having 8 very substantially different melting point
and is made by carrying out the reaction for a very much
longer period than that used in producing the Bis(acetophenone)
~ellurium dichoride which latter is in the form of white,
~; crystalline needles having a melting point of 188-190 C.
.~ .~ ' .
. . .
-16-
,'`
' ~ bm/~
. ~ - .
i831 ~9
,
: The "yellow" compound, as such~ ls.sensitlYe in a range up to
about 550 nm and, thus, includes the visible range. In gen-
eral, with the "yellow" variants of the imaging materials, it
is desirable to utilize developing temperatures somewhat lower .`~ :
than those most desirably used with the non-yellow variants.
Thus, by way of ~llustration, if a developing temperature of
150~ C is substantially optimum for a specified period of
time using, say, white Bis(acetophenone) tellurium dichloride
as the imaging material, in con~unction with a separate or ~.
extraneous æensitizer, a somewhat lower developing temperature,
for instance, 120C, may sometimes desirably be.used with the
"yellow" variants of said...imaging material so.as to reduce .
fogging effects in the developed image. Generally speaking,
this ~yellow" variant has less latitude in the thermal develop-
ment step than the purified white compound.
; Compound t64), as noted above, is a "self-sensitized"
imaging material which i8 operative in the visible range with-
out the necessity of utilizing a separate sensitizer. How-
ever, if desired, separate sensitizers can be added thereto.
.~ 20 (68) "Yellow" adduct from Bis(2-acetylthiophene)
ellurium dichloride synthesis
-:` In preparation of the "white" Bis(2-acetylthiophene)
~ tellurium dichloride (see Example (9)) in which 2~acetylthio--
.. phene is reacted with tellurium tetrachloride, which is pro-
duced by the general procedure referred to above for the pro-
. duction of "white" Bis~acetophenone) tellurium dichloride, a
reaction time of about 5 hours is employed. In the produc-
tion of the "yellow" variant of Bis(2-acetylthiophene) tel-
.~ lurium dichloride, a reaction time of 60 hours, under stirring
' ~
.
-17- :
:.
bm/-~
g
~onditions~ a~ x~om temper~t~re i~ used as a result of which
a brown solution results. On standing7 o~ange crystals form
from 1.0 g ketone and 1/2 equivalent of TeC14 having a melting
point o~ 142-145 C; 0.66 g I.R. (KBr) 1575 cm and 1515.
In contrast thereto, the "white" compound of Example (9) has
a melting point of 184-185 C. The "yellow" adduc~ from 2-
acetylth~ophene and tellurium tetrachloride has a sensitivity
in the range up to about 550 ~m or slightly higher.
Compounds (60) and (61), for instance, among others, are
"self-sensitized" imaging compounds which are operative in the
visible range without the necessity of utilizing a separate
sensitizer.
The imaging compounds of the present invention can also
be present in the form of organo-tellurium polymers. Thus,
for instance, acetophenone tellurium trichloride and analogous
or slmilar imaging compounds, disclosed above, can be condensed
with polymer ketones, such as acetylpolystyrene, acetyl-methyl-
polystyrene and polyvinyl methyl ketone, illustrative of which
is the following:
(69) Acetophenone tellurium trichloride (3.0g, 8~5 x 10 3
mole) and acetylpolystyrene (0.6g, 4.0 x 10 mole) in chloro-
form are stirred for 2 hours. Removal of the solvent gives a
J
solid which is then washed with diethyl ether. This solid
darkens at 175C and decomposes at 190-200C. This and simi-
lar polymers can have variable molecular weights, the polymers
. . .
from which they are produced, such as acetylpolystyrene, ~;
' ' .: '
.: . ~ .
, :
:
-18-
bm/ ~
. commonly having molecular weights generally ~n the range of
about 2,000 to about 30,000, but which may be somewhat lower
or very substantially ,higher. The finished polymers can
serve not only as imaging compounds but, in certain cases, ~.
dually as the matrix or in admixture with other imaging com- : ~
pounds and/or other matrix materials for the achievement of ~.
: the objectives and in accordance with the teachings of the
present invention.
At least in many,. if not in most, cases, if th~ organo-
tellurium compound is of a character such that, when heated
to its melting temperature and maintained at such temperature
for a reasonable period of time, it decomposes to produce
. metallic tellurium, then it will be useful as an imaging material
when employed under the conditions and for the purposes of the
present invention. Such organo-tellurium compound~ are, for
the purposes of the present invention, characterized generically
as "imaging organo-tellurium materials".
Many of the imaging organo-tellurium materials described
; above as, for instance, those of Examples (1), (2), (3), (4),
(15), (16), (17), and numerous others, although, for conven-
~ ience, designated herein as imaging organo-tellurium materials,
require the utilization in conjunction therewith of a sensitizer
iII order to produce a latent image when subjected to imaging
: energy or actinic irradiation, such as ultraviolet light or
visible light, or other forms of imaging energy. In certain
cases, and as has been indicated above, impurities
,`' ' :
'- . ,
. 30
. .
' `'
.~ `
.' . .
~ .' 3 -~,~
. . . : ~
1(~i1~9
present as a result of the commercial manufacture of the
- imaging or~ano-tellurium materials function as sensitizers.
Thus, for instance, in the production of Bis(acetophenone)
tellurium dichloride, acetophenone is commonly present as an
impurity and it functions as a sensitizer. Pure Bis(aceto-
phenone) tellurium dichloride is essentially light insensitive.
In certain other instances some breakdown of a~ imaging material
for instance, through hydrolysis, produces two species of
degradation products, one of which can function as a sensitizer
and the other as a source of tellurium. In other cases, and
in generally predominately the number of cases, a separate
sensitizer is required to be added in order to produce a latent
image or a sufficient latent image upon exposure of the imaging
material to imaging energy which thereafter, on development by
exposure, for instance, to dry heat, or by wet development, or
by a combination of wet development and heat, results in
production of the final image.
The matrix materials, into which the imaglng organo-
tellurium materials, and the separate sensitizers when employed,
"! 20 are incorporated to produce the imaging film or coating, are
,, :
; solids at room temperature, and they can be selected from a
relatively large number of materials. They should desirably
~; be at least in part of amorphous character and it is especially
desirable that they be glassy, polar amorphous materials having
; a glass transition temperature, which desirably should not
exceed about 200C and may be as low as
'' -'
.
''
~ c~ -20-
., ' .
:: ~ ' : ., . :
about 50C, and , better still, should be within the range of
about 80-120C. They are generally polymeric materials.
Illustra~ive thereof are cyanoethylated starches, celluloses
and amyloses having a degree of substitu~ion of cyanoethylation
of > 2; polyvinyl-benzophenone; polyvinylidene chloride; poly-
ethylene terephthalate ("MYLAR"~); cellulose esters and ethers
such as cellulose acetate, cellulose propionate, cellulose
butyrate, methyl cellulose, ethyl cellulose~ hydroxy-propyl
cellulose; polyvinylcarbazole; polyvinyl chloride; polyvinyl
methyl ketone; polyvinyl alcohol; polyvinylpyrrolidone; poly-
vinyl methyl ether; polyacrylic and polym~thacrylic alkyl
egters such as polymethyl methacrylate and polyethyl methacrylate;
copolymer of polyvinyl methyl ether and maleic anyhdride;
various grades of polyvinyl formal resins such as so-called
12/85, 6/95 E, 15/9S S, 15/95 E, B-79, B-98, and the like, sold
under the trademark "FORMVAR" - (Monsanto Company).
Of especial utility is polyvinyl formal 15/95 E which is~ ;
a white, free flowing powder having a molecular weight in the
range of 24,000 - 40,000 and a formal content expressed as %
polyvinyl formal of approximately 82%, possessing high thermal
.,
stability, excellent mechanical durability, and resistance to
such materials as aliphatic hydrocarbons, and mineral, animal
and vegetable oils.
These polymeric materials or resins and their preparation
are well known to the art. In addition to their functioning
as carriers far and holding together in a unitary composition
, .
the imaging organo-tellurium materials,
.~,
~ 30
: .
~ 21-
.' '' ' .
- ~1068~
; ~~ sen~itizers and any other ingredients which may be incorporated
- into the imaging film or coating or layer and their functioning
as dry or essentially d~ry film-forming materials to ~rovide
thin films and providing mechanical durability in the finished
imaged film, at least many of them appear also to play a
chemical or physical role in the imaging process by providing,
importantly, a source of readily easily abstractable hydrogen
and, thus, appear to play a significant role in the latent
image formation mechanism, as discussed hereafter. In
certain instances, it may be desirable to decrease the viscosity
of the matrix, which can be done, by way of illustration, by
the addi~ion of certain plasticizers, for instance, dibutyl-
phthalate or diphenylphthalate, which additions tend to result
in the production of images desirably of higher optical den-
sities but which, however, also tend to have the disadvantage
of increasing background fogging.
It may be noted that matrix materials of the type which
; contain basic groups may complex with the imaging organo-
tellurium materials and, therefore, to the extent that such
complexing may occur, the use of such matrix materials should
:. .
be avoided.
., .:
The sensitizers which are useful in the practice of the
; present inventlon can be selected from a large group. They
; should be soluble or homogeneously dispersible in the matrix
material. Their selection for use in any particular imaging
compositions is influenced, in part, by the spectral sensi- -
.", , .
., :
~ 30
'
~ 22~
'' ' :'
' ,
- -, . . , , ; - ..... .. . ..
:
' 10~
tivity ranges desired. Thus, for instance, in the case of
ultraviolet (UV) and visible sensitizers, the following are
illustrative of those which can be employed and their approx-
imate spectral sensitivity range (nm):
Spectral Sensitivity
Sensitizer Range (nm)
9,10 phenanthrenequinone 200 - 400 - 500
U.V. Visible
l,l'-dibenzoylferrocene 400-600
l-phenyl-1,2-propanedione 400-S00 :
1 0 , ,
2-hydroxy-1,4-naphthoquinone 400-500
Benzil 400-450
: Furil 400-480
Diacetylferrocene 400-450
Acetylferrocene 400-450
: 1,4-bis(phenyl glyoxal) benzene 400-500
0-Naphthoquinone Up to about 560
4,5-Pyrinequinone Up to about 530
; 4,5,9,10-Pyrinequinone Up to aboue 550
. In the practice of the present invention, 9,10-phen-~ 20
anthrenequinone is especially satisfactory.
:, i ,
. The following are illustrative sensitizers which are
sensitive in the range up to about 400 nm and, therefore, are
useful only in the ultraviolet range: benzophenone; aceto-
phenone; 1,5-diphenyl-1,3,5-pentanetrione; ninhydrin ; ~,4'-
'
~ -23-
'
, ' ' ' '
81~
dibr'omobenzophenone and 1~8-dichloroanth~aquinone.
Yarious other sensitizers can be' utilized, particularly
those of the type of substituted or unsubstituted polynuclear
quinones, of which class some have'been mentioned above, and
others of which are 1,2-benzanthraquinone; 2-methylanthra~
quinone; l-chloroanthraquinone; 7,8,9,10-tetrahydronaphtha-
cenequinone; 9,10-anthraqulnone and 1-4-dimethylanthraquinone.
It will be understood that not all sensitizers will be '
effective or equally effective, with each given organo-
tellurium imaging material, even taking into account the
utilization of imaging energy in the nm sensitivity range of
the sensitizer employed and that suitable selections of combi- '
nations of particular organo-tellurium imaging materials and
; particular sensitizers will be required to be made for achiev-
ing desirable or optimum results. Such selections, however,
can be made relatively readily.
'' In general, in connection with the foregoing matters, it
.' may be noted that sensitizers have n,~* states, both singlet
;. and triplet, of lower energies than~,~* states and, at least :
in most cases, compounds which have their ~,~* states of low-
est energy wiIl not be photosensitively effective, although,
in certain limited cases, compounds which fulfill the test of
having lower energy n~* than ~* transitions do not fonction '
as photosensitive reactants. However, the above consideration
~ is, in the main, an effective one for determining in advance
'' whether a given compound will function as a photosensitizer
.. ~ .
, .
: :
-24-
bm/~'~
- ,,,~, . :
.. ' ' - . ~ : ~. . '
8~ 9
. .
for use in the practice of the present invention. In any
event, a simple preliminary empirical test in any given in-
stance can readily be carried out if desired.
For imaging purposes where a transparency is to be pro-
duced or where the image is to be detected by reflection
viewing, it is, at times, preferred that both the matrix of
amorphous material and the imaging organo-tellurium material
are transparent or at least translucent and have little or no
color. On the other hand it may be desirable to provide some
color in the layer of imaging organo-tellur~um material so as
to favor the absorption of energy of a certain wave length.
- ~ Hence, the sensitizers which are utilized can be selected to
reflect the desiderata involved. Thus, they can be of a type
which are colored, or of a type which decompose to form color-
less and transparent or translucent decomposition products.
In the imaging compositions, the proportions of the matrix,
the imsglng organo-tellurium materlal and the sensitizer are
variable. In those special cases where the imaging organo-
tellurium material utilized is one whlch also inherently or
concomitantly possesses desired sensitizing properties, as
noted above, a separate sensitizer is not necessary. It may,
however, even in such cases, be desirable to employ a separate -
or added sensitizer which may be of entirely different sensi-
tizing properties from that inherently possessed by the part-
icular imaging organo-tellurium material utilized. In any
event, generally speaking, excluding the organic solvent or
.:.
-25-
bm/~
. .
.
10~81~9
solvents, where emp~oyed as described below, at least in most
eases the matrix material, which is a normally solid material,
that is, solid at room temperature, will be employed in
amounts in excess of any one of the other materials and will
also usually be present in major amount, that is, more than
50% and broadly in the range up to 90% preferably about 60 to
70%, by weight, of the total materials present in the imaging
composition. The imaging organo-tellurium material, generally
also a normally solid material, will usually or commonly be
the next largest ingredient, and will ordinarily constitute
from about 5 to 7 to about 30%, usually about 10 or 15 to 20%,
by weight of the imaging composition. The sensitizer, where
it is a separate ingredient, which is usually a solid but may
be a liquid at room temperature, will usually be employed in
lesser proportions, commonly of the order of about 5 to 20%,
usually about 6 to 15%, by weight, of the imaging composition,
although, in certain cases the proportions thereof can be
substantially higher, approximately or even exceeding some-
. .
what the proportions of the imaging organo-tellurium material.
Again, and with further regard to the proportions of the
aforesaid ingredients, it may be sta~ed that the area density
of the sensitizer, for instance, the 9,10-phenanthrenequinone,
is desirably selected 80 that about 80% of the photons falling
on the film in the region of the absorption bands of 9,10-
phenanthrenequinone are absorbed. Considerably higher concen-
trations of 9,10-phenanthrenequinone would leave the dark side
. ~ "
' .' ,:
~'
. . .
-26-
.
bm~
,
.
of the film unexposed and no advantage would thus be 6erved.
Again, in general and for optimal results in many cases, the
mole concentration of the imaging organo-tellurium material
should be reasonably close to or roughly approximate that of
the sensitizer. The concentration of the polymer matrix
material should be sufficien~ to produce an essentially amor-
phous film without bringing about precipitation of the imaging
organo-tellurium material, the sensiti~er and other supplemen-
tal ingredients when utilized. Excess polymer matrix material
0 al80 tends to decrease the sensitivity of the film.
In certain cases, it may be desirable to include in the
imaging composition, additional or supplemental materials for
obtaining certain or special effects. Thus, for example, it
has been found that certain materials enhance the shelf life
of unexposed virgin dry film compositions of the present ln
vention and, in certain instances, also, they enhance the
sensitivity of said film compositions. Illustrative embodi-
i ments of such additional or supplemental materials, which con-
tain ether or polyether linkages in the molecules thereof, are
such materials or polymers as polyethylene-20 sorbitan mono-
. laurate; polyethylene-20 sorbitan monooleate; Polyox-10; Polyox-
80; Polyox_750; polyethylene glycol-400 distearate; polyethylene
glycol-600 distearate; poly (1,3-dioxolane); poly (tetrahydro-
furan); poly (1,3-dioxepane); poly (1,3-dioxane); polyacetal-
dehydes; polyoxymethylenes; fatty acid esters of polyoxy-
methylenes; poly (cyclohexane methylene oxide); poly (4-methyl- -
~''., .
.
.
; -27-
bm
. . .
.- . . ~,,
8~g
1~3~dioxane)j polyoxetanes~ polyphenylene oxides; poly ~3,3-
bis (halomethyl) oxocyclobutane~; poly (oxypropylene) glycol
epoxy resins; and copolymers of propylene oxides and styrene
oxideis. Such materials can be incorporated in the imaging
film compositions in varying amounts, generally from 5 to 20%
by weight of the soLid imaging film compositions. In certain
cases they enhance or prolong the shelf life or storage life,
under given storage conditions, as much as 50% or even very
substantially more timewise, and, as indicated, they also,
in var~ous cases, effectively increase film sensitivity.
Again, the inclusion in the imaging films of reducing -
sugars has been found, generally speaking, to bring about an
enhanceme~it in density of the image area (0. D. image-0. D.
, .
background), when the film is imaged as disclosed above and
then developed, for instance, at about 120-150C and for of
the order of about 15 seconds, especially where the imaging
film is freshly prepared or not older than about a day after
initial preparation. Such films, when exposed to imaging
energy and then developed resulted in the production of a
positive image (i.e. the optical denslty is greater in the non-
- exposed areas than in the exposed areas) in contrast to the
negative working s~stem which exists in the usual practice
of the present invention. The inclusion of reducing sugars
in th~ lmaging compositions also enables development of the
image, after exposure to imaging energy, to take place at lower
temperature, even at room temperatures, in a perlad of
,,, ~
. j .
:.~
, ~ ,
-28-
bm / 1.~
: . . . . .~ .
. .
t;8i~9
;~ several hours~ for instance~ co~monly in 10~12 or 15 hours.
The reducing sugars whic~ can be employed are many, illustra- -
. . ,
~ tive of which are dextrose, glucose, arabinose, erythrose,
,
- fructose, galactose, fucose, mannose and ribose. Especially
effective are dextrose, arabinosej galactose, fucose and
ribose. The reducing sugars can be used in variable amounts,
but generally in equivalent amounts, or somewhat smaller or
greater, in relation to the amount of imaging organo-tellurium
materials in the imaging compositions.
In the production of the films or thin layers of the
lmaging material compositions, which are generally prepared in
the form of solutions or homogeneous dispersions and coated
or laid down on a substrate, it is especially desirable to
dissolve or homogeneously disperse the lngredients in an or-
ganic solvent. Illustrative of suitable solvents are dimethyl-
formamide (DMF), chloroform, tetrahydrofuran (THF), dimethyl-
acetamide (DMA), dioxane dichloromethane and ethylene
dichloride, or compatible mlxtures of such organic solvents or
with other organic solvents. After the solution or homogeneous
dispersion is filmed on a substrate in any suitable manner,
the ma~or proportions of such organic solvent or solvents are
evaporated off, preferably at a relatively low temperature
; and, sometimes desirably, under subatmospheric pressures or
in vacuo, until the film or coating is substantially dry to
the touch, such dry to the touch coating being especially
... .
desirable for handling and processing purposes. Although
such films or coatings may be, generally speaking, dry to the
touch, it should be understood that this does not mean that
the film is free from organic solvent. Indeed, it has been
.
29
:'.' ' :
bm ~-
. .: , , .
. ~ .:. ,. . . . .. . . . . , . , . ,, . . ~ . , , . . . , ,, :
10~i8~4~ :
:
found that it is fre~ently yery de~ixable that the finished
, films or coatings, prlor to exposure to imaging energy, con-
tain a small percentage, commonly of the general order of
about 2 to 3~, by weight of the film or coating, or organic
solvent, for instance, dimethylformamide (DMF) since its
presence appears to play a favorable role in the sensitivity
of the system in relation to the latent image formation andtor
ultimate image Dbtained after the development step. The elim~
ination of all or essentially all of the DMF, or other organic
solvent or solvents, from the virgin film prior to the imaging
and development frequently leads to a decrease in sensivity.
In any event, in any given instance where drying of the virgin
imaBing film has been carried out to a point where essentially
no organic solvent is present, and whereby sensitivity is
unduly reduced, sensitivity can be increased or restored by
adding a small amount of organic solvent to the film prior
! to exposing it to imaging energy.
The imaging film or coating thickness are variable but
will usually fall within the range of about 1 to about 35~m
with about 5 to 15~m generally being a good average. In
thickness in terms of millimeters (mm), such may vary from
; about 0.0005 to about 0.05mm, or much greater such as from
0.05 to 5mm, the selected thickness being dependent upon the
partlcular use to which the imaging film is to be put.
,
The production of the imaging organo-tellurium materials,
and the coating, handling and processing operations, to the
.. .
:.' .
-30-
"
.
bmt ~
10~;81~9 - - - -- - -
.
extent wllich may be required, are carried out under approprl-
ate light conditlons, as those skilled in the art will readily
understand. Eor instance, the formulation of the coating com-
positlons and the coating and drylng operations are conven-
-iently carried out under amberlite filtered light (weak trans-
mission at 550 nm~. The dry film prior to imaging, is deslr-- ~
ably stored in the dark. In certain cases, avoldance of -
contact of certain of the ingredients with certain metals
may be in order where undesired reactions, such as reductions,
may occur. In general, the vessels~or containers, stirrers,
etc. utilized should be made of glass or other vitreous
materials or other materials inert to the coating ingredients
to insure against contamination or possible undesired reac-
tions. It is advantageous, in general, to prepare the imaging
compositions shortly prior to coating them on the selected
substrate. Under suitable storage conditions, which generally
are conditions of darkness and reasonable avoidance of air or
oxidizing atmospheres and humidity conditions, the stability
,
- of the imaging compositions is good. Adverse and unduly pro-
longed storage. however, adversely affects speed and contrast
in the production of the images.
,
In the utilization of the imaging films or 1ayers of
the present invention, they are subjected, for instance, through
. a suitable or desired mask, to imaging energy which may, for
instance, be by actinic light~ irradiation with u~traviolet
. ~ - - .
. ' . ' '
' ' , ' ' ~ , '
:
,
, ;. ' ' , ' ,' ' . . ' ' '
.
,,' ' ' ' ' ' '
` :~068i'~9
.
light or by visible light, depenaing, for exampl~, upon th~ -
specific imaging organo-tellu-rium material and the specific
sensitizer utilized, to form a latent lmage-wh~ch is normally
not visible to the naked eye. In an illustrative case, for
instance, in Example D below, illuminating with a Xenon lamp,
the total flux delivered to the film surface may be in the
general range of 3 x 105 to 106 ergs/cm of film. The sub-
. : ~
sequent development, to develop or bring out the latent image,
is most desirably effected by the application of heat, for
.. :
example, at a temperature of about 130-160 C, preferably
about 150 C, for several seconds, say 3 to 15 or 20 seconds,
or wet development, or a combination of heat and wet develop-
ment. Heat or thermal development can be effected by various
means such as a hot plate, hot mineral oil, or hot silicone
. oil, at the aforementioned temperatures, or an infrared lamp.
The result is to produce a dark image having, for example, an
.. ~ . , . :optical density (O D.) of 1, in the area of exposure only, the
background remaining generally relatively light or clear. -
In the development step, only a small percentage of the
~20 total imaging organo-tellurium material which is present in
the matrix composition is reduced to metallic tellurium. After
t~e development, the film or layer may be, and desirably is,
.. . .. ... .
. subjected to a ~ixing step which serves to effect removal of
the sensitizer and to inactivate the unreacted imaging organo-
tellurium material. While this can be accomplished in various
ways, a particularly effective procedure is to contact the
- '
:- - .
' ',; ~ , -
.. ..
' ' ', ' ' ' ' ' ' ~' ' ''~:' '
- iO681~
.
film, by washiny or wiping with, or spreading on, or dipping
in, chloroform/toluene (20:80 by volume~ solution-saturated
,
with ammonia or with organic amines.- This removes the sensi-
.~ , .
tizer and, of course, the color thereof, and inactivates the
imaging organo-telLurium material so that no lmage will form
with subsequent exposure and heating and, thus, stabilizes the
film. Organic amines such as trimethylamine, triethylamine,
diethylamine, triisopropylamine, aniline and benzylamine
(e.g. 10% solutions), are illustrative of those which can be
utilized. Particularly when fixed, the film does not darken,
generally speaking, unless subjected to somewhat elevated
; temperatures as, for instance, of-the order of about 90 to
,, lOOoC. - ' ~
:. - .
The following examples are illustrative of the production
o films or layers made in accordance with the present inven-
.
tion. Th~y are not to be construed ln any way as limitative
of the invention since many other films or layers can be made
in light of the guiding principles and teachlngs contained
harein.
: , .
.. . .
20 Example A --
- , -
5Q mg Bis(acetophenone) tellurium dichloride, 250 mg
'~ polyvinyl formal ("FORMVAR" 15/95 E), 20 mg o-~apthoquinone
;~ and 3 ml DMF are stirred together at room temperature until
a homogeneous yellow viscous solution is obtained. It is then
poured onto a 3" x 4" sheet of "MYhAR" to form a film or layer
33-
- - ' . - :
:~ -
,, , ~0~8~L~g
of a thic~ness of about 10,~ and then heated in an oven at
50 C for about 30-45,minutes, at whlch tlme the film or layer
is dry-to-the-touch. If desired, although in no way necessary,
the dried film may be preheated for 3 to 5 seconds at 150 C
which results in cross-linking the polymers whereby to render
the matrix more impervious to water. -
.
- Example B -~ -
Example A is carried out as described therein except that
chlorofor~ is used in~place of DMF. The film is-dried in a
well ventilated hood for 30 minutes at room temperature to
form a dry-to-the-touch film. --~
- . . .
.
Exam~_e C ~ ~ -
Example A is carried out as described therein except
that, in place of the DMF, a mixture of DMF and chloroform is
used in volume ratio of 20% DMF - 80~o chloroform. A dry-to-
the-touch film is obtained. ~ - - ~
Example D -
50 mg Bis(acetophenone) tellurium dichloride, 250 mg poly-
vinyl formal ("FORMVAR" 15/95 E), 50 mg benzophenone and 3 ml
DMF are stirred together at room temperature until a homo-
geneous viscous solution is obtained. ~It is then poured onto
a sheet of ~MYLAR~ and dried, as described in Example A, to
form a clear, dry-to-the-touch film.
.
' , ' ; ' ~: ~ . '
: ` ' ' - ' ~
' -34- -
' - ' ' : '. '
_...... .. ..... ,, . ,.. . . , ~
.
8149 - -
.
Example E
: . . .
- 50 mg acetophenone tellurium trichloride, 250 mg poly- -
.
vinyl formal ("E'ORMVAR" 15/95 E), 20-mg 4,5-Pyrinequinone and
~ 3 ml DMF are ad~ixed and coated onto "MYLAR" and heated to
- form a clear dry-to-the-touch film, in the manner described
.. . .
~ in Example A.
- : ~ . . . .
Example F -
40 mg Bis(p-methylacetophenone) tellurium dichloride, 200
mg cyanoethylated starch, 16 mg 4,5,9,10-Pyrinequinone and 2.8
. .
ml DMF are stirred together at room temperature until a homo-
geneous viscous solution is obtained. It is then poured onto
; a 3" x 4" sheet of "MYLAR" to form a film or layer of a
:
thickness of about 10~ and then heated in an oven at-50 C
for about 30-45 minutes, at which time the film or layer is
dry-to-the-touch.
,
Example G
~- 2 g of the compound of Example (15) are mixed with 5 g
.
of cyanoethylated starch and dissolved in about lOO parts by
~- weight of acetone. The solution is deposited on a glass plate
to form, after drying, a film of about 10 m thickness.~
Example H
Example A is carried out as described therein except that,
- .: . .
; in place of the use of the imaging organo-tellurium material
~- of Example A, the imaging organo-tellurium material of Example
:'
.
. .
? ~ -35-
38 is utilized.
Example I ~ - ~- - . ~
''. ' ' : .
50 mg of the compound of Example (l) above, 250-mg poly-
vinyl formal ~"FORMVAR" 15/9S E), 20 mg 9,10-Phenanthrenequi-
none and 41 mg DMF are stirred together at room temperature
until a homogeneous viscous solution is obtained~ It is then
.
poured onto a sheet of "MYLAR" to form a film having a thick-
ness of about 3~m and dried, as described in Example A, to
- form a dry-to-the-touch film. ~ ~
ExamPle J
.
- 52 mg Bis(acetophenone) tellurium dichloride, 260 mg
.
polyvinyl formal ("FORMVAR" 15/95 E), 22 mg g,10-phenanthrene-
quinone and 3 ml DMF are stirred together at room temperature
until a homogeneous yellow viscous solution is obtained. It
": . .
is then poured onto a 3" x 4" sheet of "MYLAR" to form a
. . . . , . ~ .
yellow, clear film or layer of a thickness of about 8,~m, and
: ~ then heated in an oven at 50 C for about 30-45 minutes, at
- - which time the film or layer is dry-to-the-touch. ,
!~ -
~: Example K ~ :
;, . . . .
35 mg Bis(p-methylacetophenone) tellurium dichloride, 185
mg polyvinyl formal ("FORMVAR" 15/95 E), 14 mg 9,10-phenan-
threnequinone and 2.5 ml of 70:30 DMF-chloroform are stirred
.
together at room temperature until a-homogeneous yellow viscous
solution is obtained. It is then poured onto a 3" x 4" sheet
- . . ~' ' ' ' ~' "
- : :
. . :
-36-
- ,
.
681~g
- ~ -
-of "MYLAR" to form a yellow, clear film or layer of a thic~n~ss ~
of about lO~m, and then heated in an oven-at 40 C for-about
-, - .
~ 30-45 minutes, at which time the film or layer is dry-to-the-
touch.
; . Example L
~ 16 mg Bistacetophenone) tellurium dichloride, 77.6 mg
:, :
. polyvinyl formal ("FORMVAR" 15/95 E), 6.7 mg 9,10-phenanthrene-
- quinone and 3 ml of a solution of 5 parts by volume of DMF and
: - 1 part by volume of chloroform are stirred together at room
i 10 temperature until a homogeneous yellow viscous solution is
obtained. It is coated on a MYLAR substrate and heated as :;
described in Example J.
-
. 25 mg Bis(acetophenone) tellurium dichloride, 125 mg poly-
: .
vinyl formal ("FORMVAR" 15/95 E), 50 mg polyoxyethylene (20)
sorbitan monolaurate, 7 mg 9,10-phenanthrenequinone and 3 ml
'
: of a solution of DMF and chloroform, as described in Example :
.: : . .
: L, are stirred together at room temperature until a homo~
. : - - ,
:~ : geneous yellow viscous solution is obtained, which is then
-20 coated on a Mylar substrate and heated as descrlbed in Example
J.
:, . . _ . : :~ ~, .
: - . : ~
.Examele N
.. , ~ ,
An imaging composition is made using 0.050g of compound
(1), 0.020g of 9,10-phenanthreneguinone, 0.25g polyvinyl
. .. ~ .
''' . ' ~ ' ~ . . . .
:, - :
.
. . .
:' ~' . , - , : ' ~
- 10~81~9
.
.
formal ("E'ORMV~R" 15/~5 ~) and DMF/dichloromethane-2.25/0.75
~ ml. The composition is coated uniformly onto a sheet of -~
- , - - ~' ~
"MYLAR" having an area of 12 square inches and dried at 50 C ~ ~
- . ~
for 45 minutes. It is then imaged by expo~ure to a xenon
flash from a type 700 Honeywell flash gun for about 2m sec.
.
It is then exposed by subjecting it to a heat lamp at 150 C -
for 20 seconds to produce a visible image with good contrast.
:
~ The invent~ion will be further illustrated in connection
., .
~; with the accompanying drawings in which~
: . . - ~ :- .
~ Fig. 1 is a schematical fragmentary cross-sectional repre-
, - sentation of a starting structure of the invention comprising
.
a layer containing an imaging organo-tellurium material and
i being selectively subjected to imaging energy through an open-
-
ing in a mask.
, - .
Fig. 2 is similar to Fig. 1, indicating the latent image,
, . . .
thoùgh not visible to the naked eye, formed by the selective
. _ ,, . ..................... . : -
application o imaging energy.
.~
Fig. 3 is similar to Fig. 2 but showing the mask removed
-; and development energy being applled to the structure.
20Fig. 4 is simiiar to Fig. 1 but showing the structure
fully developed.
- . -
Fig. 5 is a schematic representation of a photomicrograph
~-showing in a 2000X enlargement a portion of an area containing
a deposit of crystalline image formeF
.
Referring to the drawings, the structure shown in Fig. 1
comprises a substrate 12 such as glassJ~n which lS deposited
- - : - :
.
.
- ~ ` ,
- .
.
- ': ' - - '
, . . . . .
- 10t;81'~Y
a thin, light transmissive layer 14 comprlsing a matrix o~- a
glassy, amorphous material such as polyvinyl formal and dls- ~-
tributed thereln an imaging organo-tellurium material and a
sensitizer, as shown, for instance, in illustrative Examples
A-N, inclusive. Upon the layer 14 of the structure is placed
an imaging mask 16 comprising opa~ue areas 18 and light trans-
missive area 20. Electromagnetic radiation or actinic light 22
is shown falling through light transmissive area 20 of the mask
onto the portion of layer 14 underlying area 20 of the mask.
The radiation is being applied in form of a short pulse. In
Fig. 2 is shown the structure of Pig. 1 after termination of
the application of electromagnetic radiation. In layer 14 is
indicated by small wavy lines the presence of latent image 24,
even though, as pointed out above, ~this latent image is gen-
erally not visible to the naked eye.
.. .
In ~ig. 3-is shown the structure of Fig. 2, with latent
image 24 in the center section of layer 14. The mask 16 has ~ -
been removed. The structure is shown suspended above the
source 26 of radiant heat energy, such as an electrical heater,
~ ' . : . . . .
20the temperature of which is controlled in the deslred range,
for instance, 130-150C. Radiant heat energy 28 is shown ~o
pass through substrate 12 to heat up the layer ~4. As layer
14 is being heated a chemical reaction takes place in the area
~ .containing the latent image 24, whereby the tellurium of the
above-mentioned imaging material is set free from its bonding
: . . . : ,
in the compound (1) and precipitated in elementary form in
-39_ ` ~
";' ~ '', ,1. ' ' . ' -
.,''' ' ~ . : ~
'' ' . ' ~ ''
~ 10~81~9- ~
-layer 14. -~*~ tellurium is present in the area correspondillg
to the latent image 24 in the layer 14 in form of needles or
needle crystallites of very small size. The structure as it
appears after completion of the heating step is shown in ~lg.
:
4 comprising an opaque section 30 in the center, where the
radiation strikes layer 14, and light transmissive section 3
representing the areas pro~ected by the opaque areas 18 of
mask 16 (Fig. l) from the radiation.
-
If the su~strate 12 is light transmissive or transparent,lO such as glass, upon viewing through the structure, area 30 is
dark or essentially non-transmissive for light, while areas 32
are highly light transmissive. Such structure, therefore,
renresents a transparency.
If the substrate 12 is a non-transparent but ~ighly reflec-
tive material such as white paper and layer 14 is originally
light transmissive, upon viewing, area 32 will appear white
and show the reflectance of the paper, while area 30 is non-
reflective appearing dark or black upon reflective viewing. ;
The separation line at 34 in the structure of Flg. 4 is20 photographed at an enlargement of 2000X. The appearan~ of
the photomicrograph so obtained is sche~atically represented
in Fig. 5. The separation line of trans~arent and opaque areas
is indicated by the arrow at 34. To the left in the light
transmissive area 32 appear no ~r only a few larger crystals
35 of tellurium while to the right clouds of small particles
36 can be seen. By visual inspe~tion under the microscope it
is seen that there are scattered particles of tellurium
, , I : - '
, ' . ~
.
'.
.
,` . 10~1~9 - ~ ~
needles in the layer 14 whic'h produce the opaqueness of area 30.
In the example of the image illustratcd in Fig. 5, the
tellurium particles representing the-image former in area 30,
preferably and advantageously in the form of needles, have a
very narrow size distribution. This is a very favorable char~
acteristic of the imaging organo-tellurium materials of the
present invention, since it permits the making of high quallty
images of uniform properties. ~It permits also to produce a
well-balanced gray scale. By varying the compositlon of the
imaging organo-tellurium materials, by varyiny-the concentra-
tion of the imaging organo-tellurium materlals in the glassy
matrix material and/or by varying the proportion of the sensi-
tizer and by adjusting the imaging and developing conditions,
such as the intensity and duration of application of the ima-
ging energy and the intensity and duration of the application
of the developing energy, the tellurium particle sizes, notably
the length of the tellurium needles constituting the imagq
former, may be controlled. Depending on the intended use of the
.
image, one will favor extremely small size needles. In certain
cases, increasing the length of the tellurium needles will in-
~:, .
cresse the relative density and contrast, but may reduce the
" ' resolution potential of the system. In general, the greater
the length of the tellurium needles, leaving everyt'hing else
;~ , .
' equal, the more pronounced will be the photographic gain and
"` : :
' '
, ~ . . . .
-41-
.
. .
10~8149 :
- .the photographic speed of the system. The selection of
particular imaging organo-tellurium materials which possess
variab~e chemical or other reactivity enables the production of
novel photographic systems which, with respect to the resolution,
sensitivity to ambient light, photographic sensitivity, speed ;;~
of development and access to the image, fill various of the
i needs for which photographic systems are presently used or may
be beneficially used.
In another illustrative embodiment of the present invention,
utilizing the imaging film of Example G in the structure shown
in Fig. 1, an electronic flash gun is used to provide an about
1 millisecond flash of broad spectrum light. The layered
A`~' structure is then placed for 3 to lS seconds onto a hotplate,
at a temperature of about 130-140C, whereby almost instantly
a sharp image appears which is an exact negative duplicate of
the image represented by the imaging mask. The image has ex-
cellent resolution and sharpness. When a sample is made from
the "white" imaging compound of Example (1) and con~aining
some acetophenone and flashed in the manner noted above, no
change in the film can be observed by the naked eye. Upon
heating, as described, an image of good contrast and definition
appears.
. ~ , ,.
Although the imaging organo-tellurium material used in
the preparation of the imaging film are commonly crystalline
o; in character, the virgin film as laid down in a dry-to-the-
touch film on the substrate, and prior to the initial imaging
step, appears generally or usually to be non-crystalline so far
. . .
41
- 30
.-; . . :
~ -42-
.~
..
::. , . . . . :., -
. .
.
10tj8149 . ~:
, j : - . -
~` as has be~n det~rmined by X-ray diffraction testing. After the
development step, the ~etallic tellurium, advantageously in
needle form, appears although particle size and shape due to
nucleation and perhaps other forces cause modifications, the
- . . . . ~
exact nature and character of which have not yet been fully
delineated. The size of the metallic tellurium needles appears
to be affeçted by such considerations as the imaging film
thickness, the chara~ter and viscosity of the matrix, the
:~: ' .
presence and the amount of organic solvent in the film when
subjected to imaging energy, and the temperature at which
development is effected which also bears upon the color of the
' , . ~: . ' ~ -
- flnal lmage. ~ ~
Depending on the desired result in the particular system
used, the thickness of the layer 14 (Fig. 1) in the structure
of the invention may ke varied in wide limits, as heretofore
:. . . : .
noted. The layer containing the imaging organo-tellurium ma--
. . O
terial may be as thin as lOOOA or less and as thick a~ lmm or -
more. For producing transparencies or reflection copies, layer
;: .- . , ' - - . ' '
thicknesses of about 0.2~m to about 20,~m are generally most
favorable. The most desirable thickness of the layer depends
on such factors as the concentratlon of the imaging organo-
- tellurium material in the matrix,~the nature of the image
former, the maximum density desired, the differential in re-
flection or transmissiveness desired, and on many other factors.
In each system one can readily determine the most favorable
thickness of the layer by considering these factors. For cer-
tain purposes such as recording information in data processing
`~ . ' - :
~ --
': . .
' . '
.. . ' " ~ I ' ' "' ., ' . : '
8 1 ~9
equipment, the layers of the imaging material may be much
thicker or thinner tha~ the above stated figures, The forma-
- .
tion of nuclei and of the preferred image forming crystallites
-~ is influenced to some degree by the thickness of the film.
. ~
Apparently, surface effects and interfacial effects must be
considered in the nucleation reaction and in the reaction lead-
..
ing to the small image forming-crystallites. In selecting the
most favorable film thickness of the imaging layer, therefore,
also these factors must be considered. ~ ~ ~
:
}0 Similar considerations apply to the selection of the con-
:,
centration of the imaging material in the matrix material.
.
Generally, it is desirable to use the imaging material in as
:
- high a concentration as is possible. The functions served by
the matrix material have been noted above and require no rei-
teration. The matrix material itself, and the inclusion of
.
plasticizers, if desired, tend to function as solvents for the
:,`', . :. '
- imaging materials and to render the film, as deposited and
~ dried, amorphous in character. The compatibility of the ma-
".~ . .
trix material and the imaging organo-tellurium materials appears
to a~d to the sensitivity of a given system and pro~ides better
~. .
images or better contrast and higher density.
.
Another relevant consideration is the relationship of the
-
glass transition temperature of the matrix material and the
temperature at which cleavage of the molecule of the imaging
.
organo-tellurium material used in each instance occurs under
~ ~ the particular xeaction condition and in the particular sur-
: ' ' ' ' ' ' '
.
-44-
.
. . .
.
. .
_ _ . . _ .. . . . .. . . . . ... , . . _ . . ., ~ .. . ... .. . ..... _ . .. . . ... . .. ..... ,. ... . . _ ._ ,
. j . . , _
106814~
. ` .- .
roundings. If, for instance, the molecule of the imaging or-
gano-tellurium material starts to decompose or cleave at a
temperature much lower than that o- the film, secondary reac-
- tions may take place locally which inactivate-all or part of
the cleavage products of the imaging organo-tellurium material
whlch, therefore, lowers the efficiency of the particular
imaging system. In certain systems it may be-desirable that
the cleavage of the imaging organo-tellurium material is inlti-
ated at a lower temperature than the glass transition t'empera-
ture of the matrix material, and, when the glass tr-ansition
temperature is reached in the deveiopment step, reaction prod-
ucts migrate to the nucleation sites, delivering the atoms of
the metallic tellurium for the building up of the image-form-
~ ~ . ... . .
ing tellurium needles. Hence, by careful correlation of these
, factors, better imaging performance can be achieved.
... . .
With regard to the substrates, which have been mentibned
above and of which certain illustrative examples have been
given, it may be observed that the substrate may be any material
capable of forming a film or plate, provided that it has a
melting or softening point higher than the temperature utilized -
for the development of the latent image, and provided it is
sufficiently unreactive so as not to interfere with the imaging
reaction. Suitable substrates are glass, mica, polyamides,
polyesters, polystyrenes, hardened condensation polymers such
as of the epoxy type, etc. Many heat resistant polymers are
.
commercially avallable which fulfill these conditions in an
excellent manner, and which, therefore, are excell~ntly suited
: ` . :
: -
.. .. . . - . . ~ ..
10~i81~9
as substrates in the im~yillg structure o~- the present invention.
~or most commercial applications of the imaging organo-tellur-
ium materials it is desirable that the substrate be flexible
so as to permit use in the form of continuous rolls in printers ~ ;
and in readers. If transparencies are to be produced in a
particular imaging system, it is, of coursei desirable that
the substrate be light transmissive. On the o*her hand, if
copies are to produced which are to be detected by reflectlon
viewing, it is preferred that a substrate be used which has a
~10 high reflectance such as heavily filled white or colored card-
board and other similar structures.
In certain cases, if desired, the substrate may be omitted
and layer 14 may be used as a self-supporting structure whlch
is imaged and developed while, for in~stance, supported on a
temporary supporting structure. In this case, the finished
~, .
image structure consists merely of a thin film of the amorphous
- glassy matrix material containing incorporated therein the
imaging organo-tellurium material and sensitizer, plus such
additives or supplemental materials as may be used, and the
- ~ .
~ image former precipitated therefrom and transformed therein.
While, as described above, the component ingredients of
~; the imaging composition, namely, the matrix material, the imag-
ing organo-tellurium material and the sensitizer, plus such
.
additional or supplemental materials as may be incorporated
therewith to obtain particular special properties, are admixed
and embodied in a single layer, or as a single layer on a
, . ' .
.~ ` - ' .
-46-
' .
,' ~ -
,: - . .
106~ 9
~selected substrate, it is within the scope of the invention to
- utilize a multi-layer system, more particularly a two-layer
system. Thus, by way o~ illustration, one layer can include
the sensitizer, ~or instance, 9,10-phenanthrenequinone carried
or distributed in the matrix, for instance, a polyvinyl formal,
and supported on a substrate, say a "MYLAR" sheet; and the
other layer can include the imaging organo-tellurium material
carried or distributed in the matrix, which may be the same or
a different matrix but, desirably, is the same matrix, and said
layer is, likewise, supported on a substrate, say, again a
"MYLAR" sheet. Such additional or supplemental materials as
may be utilized can be incorporated in whole or in part in
either of said layers or distributed through both of said layers.
Exposure to imaging energy is then carried out of only the
layer containing the sensitizer in which the latent ima8e is
formed. The production of the developed or visible image can
then be effected, for instance, by pressing the latent image
layer against or onto the imaging organo-tellurium material -
containing layer, in generally sandwich form, and then sub-
iecting the assembly to heat, say at about 150C for, forinstance, of the order of about 15 seconds, the heat being
applied from either or both sides through the "MYLAR" substrate
or substrates. An image of generally neutral tone promptly
appears. This type of procedure provides a favorable alinement
simply and with no criticality requirements.
In certain cases, preheating of the virgin imaging film,
prior to exposure to imaging energy, at a temperature in the
:
~ -47-
.. .. .
10~ 4~
.
range of 80-150C ~or a few or several scconds, enhances r~sis-
- tance of the virgin i~aging film to moisture without adversely
affecting thesensitivity of the film.
As noted previously, various forms of energy may be used
as the imaging energy and as the development energy. This
may include electromagnetic radlation, heat, electrons, elec-
trical current, monochromatic light, etc. The preferred energy
depends also on whether a negative working or a positive working
system is employed. In the imaging step, actinic light or
'
electromagnetic radiation is generally used for this step, for
instance, light of a wave length of 450nm using a Bausch and
Lomb monochromator and a 150 watt Xenon lamp. Radiant electro-
magnetic radiation is usually best suited to produce an image
by pro~ection or by the use of a mask and the like. It is also
generally suited best for producing an image having a desired
gray scale or tonal gradation. Which kind of electromagnetic
radiation or other radiant energy and which wavelength is used
.
in a particular~insta~ce depends on the task to be performed
and on the particular sensitivity of the imaying organo-tellur-
ium material empolyed. Various of such imaging materials, in
the presence of a sensitizer, inherently present or separately
added, are sensitive to actinic radiation including laser
energy and the like. If a give~, selected imaging organo-tel-
lurium material is per se insensitive to,~or does not have its
optimum sensitivity at, a wave length of actinic light or e]ec-
- ~ tromagnetic radlation, which lS to be used or available for
imaging, selected sensitizers, as noted and indicated above,
are added tp render the said imaging matcrial sensitive or to
shift the sensitivity into the desired range. In this manner,
-
48-
; . . .. _
,
8149
one can, for instance, use an imaging organo-tellurium material
which has its maximum sensitivity in the U.V. range of wave-
length to a sensitivity in the range of visible light or for
X-rays, etc. Similar considerations apply with respect to the
energy used in the development step. Most desirably and
advantageously, heat is used for the development. This may be
radiant heat such as infrared radiation or microwaves or hot
air or heat by contact and convection from a heated body, or
it may be heat from a heated wet developing bath. The use of
heat for the development offers the advantage that heat may
readily be controlled as to intensity and duration. Heat is
also inexpensively available from inexpensive equipment.
However, if desired, any of the other energy forms may be used
for bringing about development of the exposed imaging organo-
tellurium material, provided it is susceptible to this form
of energy.
In each of the imaging and development steps, a combin-
:
ation of different forms of energy may be used. In this case
it is preferred to employ a combination of the energy most
effective for imaging and of the energy most effective for the
development. The development heat may also be supplied by -
; heat generated by the absorption of electromagnetic radiation
as is the case with lasers. Incandescent lamps, infrared
lamps, laser beams, electronic or bulb photoflash units,
mercury quartz lamps, etc. can be used for the imaging. In
; some cases, similar, as well as, of course, other sources can
be used for the development.
' , ' ' ~'
~ ~ -49-
~068~9
The energy may be applied for different lengths of time
depending on the intensity of the energy source used. With
- high energy imaging sources, pulses of a microsecond or less
to a few milliseconds or more are commonly sufficient to com-
- plete the imaging. With lower intensity energy sources, longer
.;
times as, for instance, a fraction of a second to several
seconds or from 20 to 90 seconds, or more, can be used. De-
pending on the intended use of the images and on whether or
not insensitivity to ambient light is desired, one wili select
one or the other imaging organo-tellurium materials and adapt
the imaging time and the intensity and the kind of imaging
energy to the requirements of the selected imaging organo-
tellurium material.
The time of development depends also to a degree on the
intensity of the development energy employed, though in this
case usually a threshold energy exists which must be exceeded.
- This threshold is one of intensity - of temperature in the
.
case of heat energy - and must be exceeded to effect develop-
ment. With the observance of this precaution, development is
completed in a second or a few seconds or longer, for instance,
of the order of 15 to 20 seconds or, generally, ln the range
of 5 seconds to 2 minutes, depending on the tempcrature utilized
and on the nature of or the particulax imaging organo-tellur-
ium material used. The thickness of the layer of said imaging
--S O-- '
' '. i ' :
., ~ ' ` '
,,
i - 1068149
material and thc thicknes~ of the substrate may also affect
- the time required for development. However-, in all instances,
.~ .
developm~nt is quite xapid so that the said imaging materials
and the method of the invention provide reasonably rapid
access to the finished stable image. Genera11y speaking,
speed and contrast increase with'higher temperatures and longer '
- 'development times. ' ~ -
:
Depending'on the composition of the imaging organo-tellur-
ium material, for instance, lt may be desirable to effect the
10 ~ development at a predetermined temperature. As stated, the
temperature of development should be adjusted to a level above
the threshold, at which the reactions, leading to the formation
,
of the image former, to wit, the precipitation of the met'allic
tellurium needles, take place. On the other hand, the temp-
' erature should not be high enough to cause the thermally in-
.~ .
duced nucleation and reaction in the areas which have not been
subjected to the imaging energy. Usually, the range between
these two temperature limits is rather wide, and the tempera- ''
- ture can be readily adjusted to fall into the intermediate,
useful range. If these precau~ions are observed, an image of
' high contrast with low nucleation in the background areas is
. , .
obtained. In general, where heat development, and particularly
. . .
' _ dry heat development, is employed, the development temperatures
wlll commonly fall within the range of about 120-170C, it
being understood that, generally, the lower the development
temperature the longer will the heating time be-required for
:, ~
.
.. . .
~ 51- - -
'', . ' . ' . ,
; ~ ~
~06~314~
producing the sc~ne optical density. Generally, also, there
are, commonly, differe~ces iD shad~s of the final image de- - - -
pending upon the development temperature employed. Thus, for
instance, in the embodiment of Example A, a development temp-
erature of about 130C produces a brownish image whereas a
development temperature of 150-160C produces a blueish-black
image, a situation which possibly may be due to differences
in size of the tellurium needle crystallites. Again, generally
speaking, the effect of appr~ciably increasing the concentra-
tion of the imaging organo-tellurium material and the sensi-
tizer is to enable lower development temperatures to be em-
ployed where thermal development procedures are utilized.
In the thermal development step, depending upon the particular
imaging organo-tellurium material employed but, for instance,
in the case of such illustrative compounds as those o~ the
; ~ above Examples 1,2 and 3, volatiles are released, such as
hydrochloric acid, during the initial stages of decomposltion
- - of the imaging organo-tellurium materials, whlch may, and
~ appear to, have an accelerating or autocatalytic effect in the~
reduction reaction which ultimately results in the formation
of tellurium needles and may play a role in such amplificatlon
as occurs in the development step.
j - Wet development can be utilized with or without heat, and,
; where heat is utllized in conjunction with wet development,
;- such heat can be applied extraneously by a heat lamp such as
an infrared lamp or the like, or the wet developing bath may
':
- - :
-52-
.. . .
. . . : . , ~ Ir
10t;81~9
be applied hot. Such wet development baths may be of various
compositions, illustra,tive thereof belng baths consisting of
a hydrogenated veget~ble oil or a silicone oii or such an oil
- in admixture with minor proportiorsof DMF and/or a~reducing ~ -~
agent such as hydrofquinone or reducing sugars such as glucose
or dextrose. The DMF functions as a swelling a~ent for the
development of latent image fonmed from a film such as-that of
Example J, and the effect appears to produce an increase in
~photographic speed with the realizati n of an appreciable gain
.: . -, - ~
10factor, particularly where the sènsitiz~er, such as 9,10-phen- ~
anthrenequinone, is used in the higher ranges of concentration
: . , -. . . .. .
;~ ~in the imaging film compositions.
-In any event, after initial exposure to imaging energy,~
the thus exposed or iatent imaged film can be developed immed-
iately or, if desired, even after days or many weeks in stor-
age in the dark or under other non-development storage condi-
tions.
~ In certain cases, after the formation of the latent image
`~ i by exposure to imaging energy, the layer or film, p-rior to.. , - , - -
~ development, may be treated with an organic solvent or mixture
of organic solvents, for instance, such as DM~ or mixtures of
,;. ,' : ~ . .
DMF and acetone, to wash out the unreacted sensitizer, while
leaving the latent image essentlally unaffected. Then said
~ layer or film containing the latent image is then subjected to
- ~ development energy to form the visible image. This procedure,
~ ~ in certain cases, appears to play a favorable role in regard to
~ , .
; ,. . .
. - , ~ . . ' ' ':
~0tj81~9
gain considerations.
The mechanisms ,of the reactions occurring in the practice
of the present inventlon have not been entlrely elucidate~,
but it appears that exposure of the compositions containing
the imaging organo-telluri~n materials to imaging energy causes
the organo-tellurium materials to undergo an electronic altera-
tion to an excited state brought about by energy-transfer from
the sensitizer and/or by direct excitation~ of the organo-tel-
lurium molecule, with the formation of appreciable numbers of
nucleation sites or points in the imaged areas and wit'h sub-
stantially no or very few such sites or points in t'he unlmaged
areas. It appears, further, that absorption of the imaging
energy by the sensitizer to form the nucleation sites or points
occurs initially on exposure of t'he imaging organo-tellurium
material and sensitizer (whether the latter is inherently
present by reason of the particular chemical structure of the
. ..
imaging organo-tellurium material, or by the presence of a
- decomposition produc~ having sensitive properties, or by the
" :
- addition of a separate or extraneous sensitizer)'by a hydrogen
abstraction mechanism from the polymeric matrix material or t'he ~'
like. The latent image is apparently the result of a chemical
., .
modification or photochemical reduction of the sensitizer by
. . .
the imaging energy in the presence of the imaging organo-tel-
lurium material. It appears, although not yet fully ascer'ain- '~'
ed, that the inltial latent image of nucleation sites or points
which is formed is not defined, produced or delineated by
metallic tellurium. It is possible t'hat the ini~ial latent
image is m~de up of several, perhaps four ox more com-
, :
,
' ' -
, . . . - ~
~068i ~9
i ` - - - :
pounds, for instance, when 9,10-phenanthrenecluinone or ana-
logous compounds are used as the sensitizer. In any event,
in the subsequent devolopment step, ~ihich provides the needed
energy to allow release of tellurium atoms from the organo-
tellurium material at the nucleation sites or points, ~hich is
especially deslrably effected thermally or by heat, the imaging
organo-tellurium material, possibly in a metastable or unstable
,
- state, is converted by reaction mechanlsmsnot fully under-
stood but which may inv~lve a reduction reaction by the hydro-
gen which was abstracted by the sensitizer from the matrlx
material or by the sensitizer car~ying said ab_~racted hydrogen,
whereby to produce a relatively appreciable number of very small
metallic tellurium particles, mainly or substantially entirely
and advantageously in the form of needles, on the aforementioned
nucleation sites or points. Electrons can also act as reducing
agents and the materials themselves can also cause reducing.
- These metallic tellurium particles, advantageously in the
form of needles, act as nuclei upon which further growth of
-metallic tellurium takes place principally at the ends of said
needles to produce longer needles which form and delineate the
final developed image. The formation of the metalllc tellur}um
needles by the reduction of the imaging organo-tellurium ma-
: terial in the system, and under the conditions existent therein
.
under the initial application o~ imaging energy followed by
- development energy, apparently brlngs about further enhancement
.
~ of the release of metallic tellurium-from the imaging organo-
-
' -55-
,
. ~06814~ -
tellurium material, ~hich forms a bountiful s~urce of tellurium,
to effect, as noted above, further buildup of metallic tellur-
ium on the initially formed metallic tellurium needles and~r
principally at the ends thereof to increase the length t-hereof.
The length-wise growth of the tellurium need1es may be enhanced
by field concentration at the sharp ends of the needles. The
-
optical density of the flnal visual image appears-to be the
result of resonant scattering in addition to light absorption
by the tellurium needles. Optical density after development
increases initially linearly and then~logarithmically with
exposure time. - -
: The occurrence of the tellurium particles, which are crys-
talline in character, is largely or substantially ubi~uitous
throughout the matrix after development, but only in the illu-
minated areas are the tellurium crystallites of such dimensions
.
as to optimize the scattering of light which is responsible for
- - the desired visual image. The formation of nuclei wl~ich occurs
in the background or non-image areas is very substantially less
., . .::
~- ~ than in the image areas, and they are very widely spaced, and -
this fact, coupled with the possibly somewhat different char-
acter of such background nuclei, results in a relatively light
background so that good contrast between the image area and the
- background area is achieved. Furthermore, by careful handling
of the imaging organo-tellurium materials from the beginning of
their production to the imaging, and by effectively excluding
carrier-formin~ energy of damaging lntensity prior to exposure
to the imaging energy and up to the time of development, the
numbcr of metallic tellurium particles in the non-image areas
can stlll be further reduced.
~5~~
.' ~--: .
~068149
The foregoirlg discussion with respect to the matter of
needle formation in the tellurium crystallltes may be somewhat
elaborated ~u,pon by~a consider~tion of the following facts in
relation, illustratively, to a film such as is produced pur-
suant to Example J above. In the virgin film, that is,prior
to exposure to imaging energy, under ex~mination using Trans-
mission Electron Microscopy (TEM), black areas appear which
indicate the presence of aggregates of the Bis(acetophenone)
tellurium dichlorlde. The same film exposed for 100 seconds
at 400nm and developed at 150C for 15 seconds~to an optical
density of 1, sho~stellurium needles having a length generally~-
' O - O
in the range of 1000 to 2500 A and a diameter of about 100 A
which are responsible for the visible image. On the other
~ hand, the same virgin or starting fllm not sub~ected to imag-
- ing energy but subjected directly to heat at 150C for 15
seconds shows the presence of metallic tellurium but the pres-
- ence of very Little or the essential absence of tellurium in
the form of needles. ~inally, the same virgin or starting
.. ~ ,
film exposed to imaging energy as described above in this para-
graph but for a period of 70 hours at 450nm, but not developed,
showed an abundance of tellurium needles.
Light or energy absorbed by the sensltizer is effective
_for the formation of the latent image, and the exposed area
becomes depleted in its content of the sensitizer in its orig-
inal form in ~he film prior to exposure. Although, as has
been indicated above, the latent image which is formed upon
-
~ 57-
.. ,' ' ~ ' .
'
. ,.. ; 10~8~
.
~posure to imaging energy lS apparently not fvrmcd or delin-
eated by metallic tellurium, lt is possible that some metallic
or crystalline tellurium, in very small amounts, may be present ~`
in the filM after exposure to imaging energy and prior to the
development step.
Briefly and generally, the imaging layer including the matrix,
the imaging organo-tellurium ma erlal and the sensitizer, as
expressed above, is essentially an amorphous structure and it
has one detectable characteristic, as for example, it being
substantially light transmitting. When the imaging layer is
subjected to imaging energy, nucleation sites or points are
; established in the imaged area of the imaging layer to provide
a latent image therein. When the so imaged layer is subjected
.
to development energy, such as heat, the imaging organo-
tellurium material is reduced and deposits small crystalline
metallic tellurium particles at said nucleation sites or points
- in the latent image, advantageously in the form of small needles,
forming small crystalline metallic tellurium nuclei upon which
; ~ further metallic tellurium is deposited by the further reduction
of the imaging organo-tellurium material to provide larger
crystalline metallic tellurium particles or needles in the imaged
area. Thus, the initial structure of the imaging organo-
tellurium material is changed to a~different structure in the
imaged area, a crystalline metallic tellurium structure, having
another detectable characteristic, for example, it being
substantially non-light transmitting. In effect, therefore, the
essentially amorphous structure of the imaging layer which is
. , , ~
~ -58-
- ~ ~
.;
' ' ' ' ' ' 1!~
106814g ~,
~ ` substantially light transmittin~ is transformed in the imaycd
;" . , -
-~ area to an essentially crystalline structure which is substan-
tlally non-light transmitting-to form a visuall~ detectable
: image. This is accomplished by the various materials, the
: . ~ - , . .
relations and reactions between the materials and the transror-
mation processes and mechanisms described herein.
, . , - ,
In summary, therefore, the mechanisms which come into play
.,- . ~ : , : :
in the present invention involve the following considerations:
.,: - - . - , :,
1. A photosensitive organo-tellurium-material
.
,~ 10 which is capa~le of excitation, under the
influence of imaging energy, and in the - -
,: . ~ - ,
presence of a sensitizer, to a reactive
,. . ~ , , .
state and optimumly with good efficiency.
2. The~ ~ * sihglet and/or the~r * triplet
.
are the most reactive states, and prefer-
ably are the lowest states of the sensi- - -
, . . . .
- tizer. ~ . -
; 3. The matrix contains readily easily ab-
: ~ ~ stractable or extractable hydrogen atoms. -
4. The excited state possesses sufficient
energy and a sufficient time period to
,
permit abstracting hydrogen atoms from
,
,~ the matrix by the sensitizer. - - ~ ~ -
5. The organo-tellurium material is one which
is reactive toward a metastable intermed-
.; ~ :
~:
- . .
........................... . ,~
~ -58~-
~, . -
.~4
.
'' : ' , ~ ~ ' -
. '
10f~8149
iate ~o yield Te needles.
-. . . , .- -: .. :
~; Films made in accordance with this invention may have
. . . ~ .
high photographic resolution, for instance, in various cases, ;~
of the order of 50~ to 600 line pairs/mm and good continuous
tone with gamma close to unity. .
The shelf life of the latent image is, generally, good.
.. . .. . ~. .
-~ On unduly prolonged storage, however, of the order of several
' ' , ' : .' ~ . ': '
days or more, development tends to occur at materially lower
temperatures than would otherwise be necessary to obtain effec-
tive thermal development. Contact of the latent imaged films
. . .: . . . ~ :
with various solvents, and dry, wet or low temperature storage '~
generally does not adversely affect the quality of the final
. . . . :
image obtained after subse~ent thermal development of the
. ' - . ' . :
; latent lmage.
; - ~ As to the developed image, its stability is, generally
, ~ speaking, ~lso good, except, for instance, in the presence of
oxidizing agents which cause fading of the image.
The foregoing discussion of the present invention sho~Js
that it provides an excellent imaging system whlch may be wide-
0 ly used for a variety of imaging tasks. The materials of the
invention may be employed in~the camera, for proofing purposes -~
~ and for duplication of images, for making duplicate copies of
microrecords ana microfiche, for recording output-information
... .
of a computer and for the output of other data storage and
retrieval systems. The broad usefulness of the new imaging
system of the invention is predicated on the quick and ready
.
: , . -
~ _59_
. . . ., ,, - .
:: : , , , ~ ,
: 10681~
- access to permanent copy of the information of the record or
image. Different methods of readout can be used based upon
differences in reflecti~ity, transparency, opaqueness, electric-
al properties, the ability to hold electrical charges, etc.
The records and images are sharp and have good to excellent
resolution. The organo-tellurium imagin~ materials used in
; the practice of the present invention can be varied from a low
gamma to high gamma as may be needed and desired in each
individual i~stance.
10In this respect, the new imaging system, generally
speaking, has much of the versatility of the established
silver halide system, which by choice of emulsions and
development conditions also permits a wide variety of gammas.
However, as is readily apparent from the foregoing, the imaging
system, as well as the development system, proper, of the
present invention does not require wet treatments and, moreover,
it provldes rapid access to the finished, stable image which
is many times not the case with the silver halide images. This
makes the new system, particularly in such instances, superior
in numbers of respects to the established silver halide systems.
The various other imaging systems which are being used
or have recently been proposed as not requiring a wet treatment
usually have the disadvantage that they are predicated on the
use of a single photosensitive material with little possibility
of varying the character of the material such as varying the
gamma of the image. They may, therefore, be suitable in one
. '
~ 60-
', ' , ~", ,., . ~
10~81fl~ :
particular application but are not suitable in any other
applications. The imaging organo-tellurium materials used in
the lmaging system of ~he present invention are, generally
speaking, inexpensive and may readily be applied by inexpensive
methods so that a low cost imaging system is provided.
The present invention does not require vacuum deposition
or sputtering of an elementary image former onto a substrate.
The imaging compositions may readily be applied in form of a
solution e.g. by wipin~, spin deposition, application by a
doctor knife, etc. The images produced by the practice of the
present invention can be used as a prin~ master, e.g. when an
image former is selected which has a capacity for acceptin~
and holding electrical charges dlfferently from the matrix
material. In this case, the images can be produced, for
instance, on a paper or cardboard substrate to provide an
inexpensive, throwaway printing master. After a desired
number of copies have been made from it, the print master is
simply discarded.
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