Note: Descriptions are shown in the official language in which they were submitted.
127~851
}I¢Al` T~ANS~A~LE l~MI~Ar~
~ACKG~OUND OF TIS~ INV~NTION
1. r~ield Or tlle Invelltlon:
The present inventlon relates to a heat transferable
label and lmproved release composltlon thereror.
2. Ve~crlptiotl of the ~rior Art:
Prlor art l~eat transrerable labels ror imprintlng
designs onto an artlcle typically lnvolve decorative
lamlnates conslstlng of a paper base sheet or web coated
witi~ a wax or polymeric release layer over whlcll a design
i8 lmprlnted in ink.
U.S. Patent 3,616,015 i8 illustrative of the prior
art. ln U.S. Patent 3,616,015 a label carrying web such
as a paper sheet lncludes a heat transrerable label
composed Or a wax release layer afflxed to a surface Or
tlle paper sl)eet a~d an lnk deslgn layer superlmposed onto
the wax release layer. In tlle heat transfer labelling
process for lmprlntlng deslgtls onto artlcles, tlle label
carrylng web 18 subJected to heat and the lamlrlate 19
pre~sed onto an artlcle wlth the ink deslgn layer nnaking
dlrect contact with tlle article. As the web or paper
~heet 19 subJected to heat, tlle wax layer beglns to melt
80 that the paper sheet can be releaaed froln tl~e wax
layer. Arter transrer Or tlle deslgn to the artlcle, tl)e
paper sheet 1~ lmmedlately removed, leavlng the deslgn
rirmly arrlxed to tlle surrace with the wax layer exposed
to the envIronment. The wax release layer should not only
permlt release Or the transferable label rrom the web upon
appllcatlon Or heat to t!le web but al80 form a clear
proteatlve layer over the transrerred lnk deslen.
, .
'`'~ ~ '' ' , '
.
~Z73851
This commonly assigned patent discloses a wax release
coating containing a modified montan wax which has been
oxidized, esterified, and partially saponified. In order to
attain improved clarity of the transferred ink design the
transferred wax coating over the ink design is subjected to
additional heat processing after the label has been
transferred onto an article. The additional processing
involves postflaming, wherein the transferred wax coating is
subjected to jets of high temperature gas either as direct
gas flame or as hot air jets at temperatures of about 300F
to 400F for a period of time sufficient to remelt the wax
coating without substantially heating the bottle. Upon
cooling of the remelted wax coating through use of ambient or
forced cooled air, the cooled wax layer solidifies to form a
clear, smooth protective coating over the transferred ink
design. Although the heat transferable label and process
disclosed in U.S. Patent 3,616,015 represents an improvement
over prior heat transferable labels, they are best suited to
decoration of plastic articles which are not transparent.
Although the heat transferable label disclosed in this
reference may be utilized for decorating a wide variety of
different plastics, there can be a degree of hazing or halo
noticeable over the transferred label when the transfer is
made onto clear plastic materials, despite use of
postflaming.
U.S. patent 2,990,311 discloses a heat transferable decal
having a release transfer layer composed of a mixture of a
crystalline wax and a synthetic thermoplastic film-forming
resin, principally an organic linear thermoplastic film-
forming resin which is substantially
, , ' ' ' . '
.
385~
water insoluble. The d~gree Or compatiblllty Or the re31n
and wax is controlled through selection and ratlo of the
components to glve heat transfers of either the hot peel
or cold peel type. In the hot peel transfer, the decal
wlll adhere and release from the backlng only lmmedlately
after appllcatlon whlle the decal 18 stlll hot. In the
cold peel transfer the transferred decal wlll adhere to
the recelvlng surface when hot but will only release and
tran~fer by peellng away the backlng arter the transfer
ha~ cooled. In elther type Or transrer~ thls rererence
teache~ that reslns and waxes (the latter belng used
for the relea~e layer) should be mutually lncompatlble or
lnsoluble at temperatures below the meltlng temperature Or
the wax such that the molten wax, upon coollng, wlll
actually arystalllze separately and dlstlnctly rrom the
re~ln. The resins are llnear thermoplastlc fllm-forming
reslns deflned as essentlally solvent-soluble, sortened by
heat and to lnvolve only a mlnor amount or no cross-
linkage.
Sultable reslns speclrlcally dlsclosed are polyvlnyl
acetate, polyethyl a¢rylate, polymethyl acrylate,
polyethyl methacrylate, polypropyl methacrylate, polybutyl
methacrylate, styrenebutadlene, acrylonltrlle-butadlene,
polychloroprene rubbers, polyvlnyl butyral, ethyl
cellulose, and polyvlnyl acetate vlnyl stearate copolymer
(col. 5, 1. 38-44). The reference teaches that the wax
¢omponent should be a materlal whlch derlves lts
crystalllnlty malnly from the presence Or lohg hydrocarbon
chalns and should melt over a relatlvely narrow range
between the temperatures Or about 50C to 110C. The
penetrometer hardness value (ASTM D5-52) when tested wlth
; 100 grams for 5 seaonds at 28C should be below about
,
,
~2738Sl
15 . Specific waxes disclosed as suitable are beeswax,
candelilla wax, carnauba wax, hydrogenated castor oil, montan
wax, paraffin wax, low molecular weight polyethylene,
oxidized microcrystalline wax, and hard wax or derivatives
thereof obtained from the Fischer Tropsch synthesis.
(co.5,1.45-56). This references does not disclose
applicant's formulation for the release layer nor does it
contemplate the advantages which applicant has derived from
such formulation.
U.S. patent 2,862,832 discloses a heat transferable decal
having a release layer composed of an oxidized wax. The
disclosure is directed principally to defining the type of
wax found to provide suitable release of the decal from the
carrier web upon application of heat. The wax disclosed in
this reference is an oxidized wax obtained as the reaction
product of the oxidation of hard, high melting, aliphatic,
hydrocarbon waxes. The oxidized waxes are defined as the
oxidation products of both natural and synthetic hydrocarbon
waxes such as petroleum waxes, low molecular weight
polyethylene and waxes obtained from the Fischer-Tropsch
synthesis. Suitable wax may include oxidized
microcrystalline wax or the esterification product of an
oxidized hydrocarbon wax. The oxidized waxes are disclosed
as those having melting points between about 50C and 110C,
saponification values between about 25 and 100, acid values
between about 5 and 40, and penetrometer hardness (ASTM D5-
52) below about 51 as measured with 100 grams for 5 seconds
at 25C.
Although this reference mentions that minor amounts of
certain additives such as fillers and resins may be added to
~f :
~ .
.,~, .
.
~738Sl
the oxidized wax, the invention is clearly concerned with the
use of wax as the essential component and designation of
specific wax types found to give advantageous results. This
reference does not disclose applicant's principal additives
or applicant's combined formulation nor does it recognize or
contemplate the advantages obtained from such formulation.
U.S. Patent 3,616,176 discloses a heat transfer laminate
of a type related to that disclosed in U.S. Patent 3,616,015.
In U.S. Patent 3,616,176 the laminate is composed of a base
sheet, with a polyamide layer covering the base sheet and a
decorative ink layer covering the polyamide layer.
Sufficient heat is applied to the laminate to heat the
polyamide layer at or above a softening point, and the
laminate is then pressed onto the surface of an article with
the decorative ink layer coming into direct contact. Upon
withdrawal of the heat source, the polyamide layer cools to a
temperature below the softening point and the base sheet is
removed. The decorative layer becomes fused or heat sealed
to the article. The polyamide layer in the disclosure
functions as a release coating which allows transfer of the
decorative layer onto an article and upon cooling serves as a
protective coating layer over the transferred decorative
layer. The use of a polyamide release coating has the
principal disadvantage in that there is a significant
tendency for the polyamide to form a noticeable halo around
the transferred decorative layer. Also the polyamide layer
even when sub~ected to additional processing such as post-
flaming does not form sufficiently clear coating that would
aesthetically permit heat transfer labelling onto clear
articles or bottles.
\-~
., ~, - - , ' :
-
1i:'7385~
U.S. patent application Serial No. 130,303, commonly
assigned with the present application, discloses a heat transfer
label of the type illustrated in U.S. patent 3,616,015. In
another form of heat transfer label developed by the Applicant, a
carrier member (base sheet) is overcoated in designated regions
with a release layer and an ink design layer. Optionally, a
barrier layer is included between the release layer and the ink
layer. The release layer is typically composed of a
polymerization product of a diamine with the dimer of a fatty
acid. In order to reduce the halo effect of the transferred
release layer over the ink design layer, the release layer is
contoured in a particular manner. To further reduce the halo
effect, this reference teaches that the optional barrier layer
included between the release layer and ink layer, be formed of an
aromatic acid-based polyester covering and overlapping the release
layer by a margin.
Applicant's U.S. patent No. 4,426,422 also discloses a
heat transfer label of the type illustrated in U.S. Patent
3,616,015. The heat transfer label disclosed in U.S. Patent No.
4,426,822 is composed of a carrier member (base sheet) overcoated
in designated regions with a release wax layer, a protective
barrier layer, an ink design layer, and an adhesive layer. The
protective (barrier) layer is placed preferably between the
release wax layer and the ink design layer. The protective layer
provides enhanced chemical resistance for the heat transfer label
, .p ', ~
~i
,
'' '"' , ' " '
,'
'
lZ738S~
-7a-
and permits the heat transfer label to resist distortion during
the heat transfer process without sacriEice in label clarity.
Accordingly, it is an object of the present invention to
provide an improved release for heat transferable substrates which
permits transfer of an ink design image from a support member to a
pla~tic or glass container.
_
A '.,, ' ' ,
''' '' ~ '
`
127385~
It 18 an important obJect to provide a relea3e whlch
has improved optical clarity and required relea3e and
adhesive properties.
It is a further ob~ect to provide an improved release
and heat transferable substrate rOr use ln transfer Or
optl¢ally clear design image from a support to a clear
plastl¢ or glass contalner. A related obJect is to
provide an improved optlcally clear release whlch also
functlorls as a prote¢tive ¢oatlng for the transrerred
image.
' ', ~'
: '........... ' '
.
.
.: , . - , .
~273851
SUMMERY OF THE INVENTION
In accomplishing the foregoing and related objects, the
invention provides a heat transferable laminate of the type
comprising a substrate affixed to a support member for transfer
from said support member to an article upon application of heat
to said support member while said article is in contact with said
substrate, said substrate comprising in sequence a release layer
in contact with the support member and an ink design layer over
the release layer, said release layer comprising in combination:
a paraffin wax composed of linear saturated Cl~ to C32 hydrocarbons
having a melting point between about 110F and 150F, a montan wax
that is oxidized, esterified, and partially saponified, and a
thermoplastic tackifying polymer chosen from the group of
transparent, nonwax hydrogenated hydrocarbon polymers having
softening points between about 60C and 135C, oxidation
resistance under ambient conditions, and has Color Gardner Nos.
of between about 1 and 4.
The invention also provides a heat transferable laminate of
the type comprising a substrate affixed to a support member for
transfer from said support member to an article upon application
of heat to said support member while said article is in contact
with said substrate, said substrate comprising in sequence a
release layer in contact with the support member and an ink
design layer over the release layer, said release layer
comprising in combination: a paraffin wax composed of linear
saturated C" to C32 hydrocarbons having a melting point between
about ~10F and 150F, a montan wax that is oxidized, esterified,
and partially saponified, and a thermoplastic tackifying polymer
chosen from the group of transparent, nonwax hydrogenated
hydrocarbon polymers having softening points between about 60C
and 135C, oxidation resistance under ambient conditions, and has
Color Gardner Nos. of between about 1 and 4, and wherein said
paraffin wax comprises between about 15 to 30 percent by weight
of said
v~
, . ~.
12'73851
-sa-
release layer, the montan wax comprises between about 15 to 35
percent by weight of said release layer, and the tackifying
polymer comprises between about 15 to 50 percent by weight of
said release layer.
An important aspect of the invention is an improved
formulation for the release layer. The improved release
formulation has the advantage that it produces an optically
clear, transparent, protective layer over the transferred ink
design layer. Consequently, the improved release coating has
distinct advantage in the application of heat transferable
laminates to plastic or glass containers, and in particular to
clear plastic or glass containers.
The clarity of the transferred release coating forming a
protective coating over the transferred ink design layer is of a
degree heretofore unachievable. The transferred release layer is
optically clear to the unaided eye when viewed against a clear
plastic or glass
B
.
, , .
, . - . .. . .
. .
. . . ~ ~ ,
, , . . - . ~
1273851
container. There 18 n~ hazlng, spotting, or halo efrect
discernlble over the tran~rerred ink design layer
regardless Or whether the heat transrerable laminate i~
applied to opaque or clear artlcles.
The improved release layer of the lnvention contalns
a crystalline wa~c such as pararrln wax or microcrystalllne
wax, and a taoklrylng agent. Preferably the lmproved
release contalns a crystalllne wax, such as parafrln wa~,
a montan wax, and tacklrylng re~ln. It has been
de'cermlned to be hlghly deslrable to sele¢t a ta¢klrylng
resln whlch 1B composed Or an optl¢ally ¢lear, nonwax
hydrocarbon polymer havlng a sortenlng polnt (Ball and
~lng method) between about 60C and 135C, preferably
between about 85C and 125C, and a ¢olor Gardner
number Or about 4 or less, more preferably between about 1
and 3. The prererred ta¢klrylng resln lmproves the
adhesiveness Or the release layer without destroylng the
release propertles Or the wa~. The ta¢klrylng resln also
enhan¢es the optl¢al clarlty Or the release layer. A
tacklrylng resln determlned to have these advantageous
propertles 18 a hydrogenated hydrooarbon resln. More
speairlcally, the hydrogenated hydrocarbon resln
determlned to have the arorementioned advantageous
;~ ~ propertles 18 the produ¢t Or a ayallc monomer whl¢h 18
25 polymerized and subsequently rully hydrogenated. The
ayclia mo~nomer 18 prererably a C4 to C8 hydroaarbon
monome~r. A prererred taaklrylng resln is the produ¢t Or
ay¢lopentadlene monomer whl¢h 18 polymerlzed and
subsequently rully hydrogenated. Another prererred
ta¢kirylng resln 18 rormed rrom the product Or styrene
monomer whl¢h 18 polymerlzed and subsequently rully
hydrogenated.
.,; , ~ :
.,;, ;: ~
J'~:
' ,:: : '
: . -. . . .
'~' '~ ~ ' ' ' -' ' ' ''
'' , . ' ' ' ~ ',' : ', ,
.
'' ' .' " , ' ' ' ' : ,
,, , ~ ,
~2738~;1
Appllcant has determined that lncluslon Or a
tacklrying re~in from the above ola~ses Or hydrogenated
hydrocarbon resin increases the adheslveness Or the
release layer wlthout destroying the release propertles of
the wax and simultaneously, qulte unexpectedly, reduces
the amount Or crystalllne structure Or the solldiried wax
to a greater degree than mlght be expected from dilutlon
Or the wax wlth other reslns or dlluents in the same
proyortlon. 1'he slgnlrl¢ant reductlon in total
crystalllnity Or the wax 18 belleved to markedly enhance
the optlcal clarlty Or the wax upon resolldirication.
A prererred rormulatlon rOr the lmproved release
coating may also include microcrystalline wax. l'he
miaro¢rystalllne wax 18 typlcally compo~ed Or saturated
hydrocarbons Or hlgher meltlng polnt than that Or pararfln
wax. The mlcrocrystalline wax is characteristlcally
composed Or about C34~l70 to C60H120 ~ydrocarb
In addition to the microcrystalline wax, the
preferred rormulation for the improved release coating may
advantageously contaln a resln blnder, whlch blnds the
components Or the relea~e ln a homogeneous mlxture which
orms a hot melt and thus obviates the need ror a solvent.
A prererred binder is a copolymer Or ethylene and
vinylacetate or a terpolymer Or ethylene, vinyl acetate
and acryllc acid.
In the preferred release rormulation, the para~rrln
wax may be present in an amount between about 15 to 30
weight percent; the montan wax between abcut 15 to 35
weight percent; and the tackirylng resin in an amount
between about 15 to 50 weight percent. The weight ratlo
Or montan wax to tackifylng resln advantageously ralls in
; the range rrom ~bout 0.3/1 to 2.3/1. The lmproved release
rormulatlon Or the lnventlon ln appllcable to any heat
,
- . : .
: . :
lZ738S:l
12
transferable lamlnateror the type whereln the ob~ective i8
to transfer an lnk deslgn lmage from a carrier web to an
artlcle upon the appllcatlon Or heat and pressure to the
lamlnate.
5 BRI~F D~SC~IPTION OF TIIE DRAWINGS
~lgure l 18 an lllu~tration Or a preferred embodlment
o~ the composlte heat transferable lamlnate; and
Figure 2 18 an lllustratlon of another preferred
embodlment of the composlte heat transferable lamlnate.
,
.
, .,: ~ .
i,
,
.' ;: . - ,
:, . ,
.
12738~ii
D~TAIL~D DESCRIPTION
The prererred embodlment of the heat transferable
lamlnate 5 Or the invention as illustrated in Figure l 18
compo~ed of a carrier web 10, typically paper, overcoated
with a release layer 20 and ink design layer 30.
Optionally an adheslve layer 4O may be included over
design layer 30 as lllustrated in~igure 2. Release layer
20, design layer 30 and optional adhesive layer 40 rorm a
transferable substrate 15, which relea~es from carrier web
10 upon application of heat to web 10 sufficient to melt
relea~e layer 20. As an artl¢le or surrace 18 pressed
onto the exposed surface Or substrate 15, it ~plits rrom
¢arrier web 10 and transrers onto the surrace Or the
article wlth ink design layer 30 clearly imprlnted on the
article.
The heat transrerable laminate Or the inventlon
satisries a number Or requirements slmultaneously.
Release layer 20 and lnk de~lgn layer 30 are first Or all
easily coated onto carrler web 10 when the release layer
20 18 in a molten state. Coatlng Or carrler 10 18 readlly
efrected preferably by gravure methods but other printing
methods such as letterpress, rlexographlc, or screen
printing as well a~ cast coating methods such as reverse
roller coatlng may be employed ln coatlng release layer 20
onto carrler web 10. Ink deslgn layer 30 is readlly
coatable on release layer 20 by use prererably Or gravure
, technique, although other cast coatlng methods and screen
printlng methods may also be used. Release layer 20 and
ink design layer 30 Or the inventlon have the required
physical properties that permit coatlng by the prererred
gravure technlque without "plck orr" problems occurrlng;
that 18, wlthout causlng removal Or a portlon Or release
- - ,
. , - ~ '-. '
lZ73~5~
14
layer 20 as the ink design layer 30 is coated thereon.
Release layer 20 also has the required properties that
prevent embossing of the wax during printing of design layer
30 and also prevents ink striking into the wax during
printing and ink migration into the wax after printing.
Release layer 20 is of a formulation which also prevents
nonuniform splitting of the release layer during the heat
transfer process and thereby prevents insufficient or uneven
transfer of the release layer from the carrier web during the
transfer process. In addition to having the requisite
release property upon heating, release layer 20 also has
sufficient adhesive properties upon cooling which keeps
design layer 30 adhesively bonded to the article being
imprinted and also forms a clear glossy protective coating
layer over the transferred design layer 30. The clarity,
smoothness, and glossiness of release layer 20 is improved by
subjecting transfer substrate 15 to postflaming after
substrate 15 has been transferred to an article. The
postflaming may be accomplished by exposing the transferred
substrate to jets of hot gas either as direct gas flame or as
hot air jets for a period of time sufficient to remelt the
wax, as for example by the methods described in U.S. patent
3,616,015. After postflaming layer 20 resolidifies quickly
upon exposure to ambient conditions to form a smooth, glossy
film of improved clarity. The resolidified layer exhibits so
high a degree of clarity and translucency that there is
virtually no visible halo or hazing either around or over the
surface of the transferred design image 30. This results in
remarkable clarity in the transferred design image. Thus,
the laminate 5 is suitably applied to plastic and glass
articles of a variety of shades, as well as to
.....
:, - .
~2738Sl
artlcles and contalne~rs composed Or optlcally clear
plastlc materlals such as polyvlnylchlorlde and
polyethylene terepthal&te or clear polyethylene or
polypropylene. Prior art heat transrerable laminates,
5 although exhibitlng hlgh degree Or optlcal clarlty upon
postrlaming, have some llmitation in application to
optically clear plastics since there can be ~ome hazlng or
halo discernible upon transrer onto optlcally clear
materlals.
The virtual eliminatlon Or hazing or halo has been
accompllshed while slmultaneously satisrying all other
physlcal property requlrements rOr an errectlve release
coatlng rOr a heat transrerable substrate as has been
discussed ln the roregoing. Addltlonally thls lmprovement
1,5 has been made wlllle redu~lng the amount Or montan wax ln
the preferred formulatlon. Slnce montan wax 1B a costly
constltuent, appllcant has reallzed slgnlrlcant cost
savlngs ln the preferred formulatlon ror release coatlng
20.
The preferred rormulatlon rOr relea~e layer 20 is a
hot melt contalning pararfin and a montan wax which may
also lnclude a minor amount Or mlcrocrystalline wax. In
additldn to these waxes, the formulation includes a
ta¢klrylng resln and sultable blnder. Appllcant has
dlscovered ~ulte unexpectedly that, wlth proper selectlon
Or tacklfler resln, the total amount Or crystalllnlty Or
the parafrln wa% can be reduced slgnlrlcantly, more than
would occur by addltlon Or other reslns or dlluents Or
equal amount. It 18 not known wlth certalnty all of the
ractors responslble for the hlgh degree Or clarlty and
translucency Or the transrerred layer 20, but the
reductlon ln lnherent crystalllne structure Or the
pararrln wax aod to an extent the mlcrocrystalllne wax, as
.
.
..
- . - . :
lZ'73~3S
16
well, 18 believed to be the principal factor. Although it
18 known that the lnherent crystallinity of certain waxes,
partlcularly pararfln wax, used in release coating ror
heat transrerable laminates is a princlpal cau~e of the
hazing erfect~ it has been heretorore not been posslble to
reduce the crystalllnlty Or the solidiried wax without
disrupting other lmportant physlcal propertles Or the
release lager. Although postrlaming serves to reduce some
Or the hazlng whi¢h appears over the transrerred lmage it
erreats only a partial reductlon and does not decrease the
crystallinlty o~ the wax components. Postflaming has been
determined to lncrease clarlty prlnclpally because lt has
the erfect Or smoothing mlcroscoplc hills and valleys on
the surrace Or the transrerred release layer. Post~lamlng
thus crea~es a smoother, more unirorm surrace Or glossy
character, lncreases the overal~ clarity Or the
transrerred release layer, and consequently the clarity of
the transrerred deslgn image. Resldual amount Or opacity
or ha~lng is believed to be caused bg the crystalllne
structure Or the solidlried pararrin wa~ and to a lesser
degree Or the ~olidlfled microcrystalline wax which
contalns crystals Or much smaller size.
It i~ deslrable to select a thermoplastlc tacklrylng
resln whlch is composed Or an optically clear, nonwax
hydrocarbon polymer havlng a sortenlng polnt (Ball h ~ing
Metkod ASTM E-28) between about 60C and 135C, more
prererably between about 85C and 125C, and most
prererably between about 100C and 125C. Appllcant
has ~ound a partlcular polymer class Or thermopl~stlc
reslns whlch when added to the release rormulatlon,
lncrease the adhesiveness Or the release layer and qulte
unexpectedly reduces the amount Or crystalllne structure
ln the solldlrled wax. Thls reduction 18 greater than
,
,
. -
, : ' '
12738Si
mlght be expected from dilution Or the wax wlth otherresln~ or dlluents added in the same proportlon. The
marked reduct~on in total crystalllnlty Or the wax, it ls
theorlzed, enhances the optical clarity Or the wax upon
resolldlricatlon. The solldlried release layer has a
color ~ardner No. between about 1 and 4. The tackirying
resln also prererably has a color Cardner number between
about 1 and 4, typlcally between about 1 and 3.
The polymer class ror the tackifylng resln having the
above-descrlbed properttes and determined to unexpectedly
reduce the amount Or crystalllne ~tructure ln the
solldiried wax 18 a transparent nonwa~ hydrogenated
hydrocarbon resin. More specirioally, lt is the product
Or a cycllo hydrocar~on monomer which has been polymerlzed
and subsequently rully hydrogenated to completely saturate
the polymer. Suitable cycllc hydrocarbon monomers which
are polymerized and subsequently rully hydrogenated to
rorm the tacklfylng resln component are prererably
selected from C4 to C8 cycll¢ hydrocarbon monomers.
A prererred tacklfylng resln is rormed Or
cyclopentadlene monomer whlch 18 polymerlzed and
8ubsequently rully hydrogenated. A tacklrylng resln Or
thls latter type employlng cyclopentadlene monomer whlch
18 polymerl~ed and subseque~tly fully hydrogenated 18
avallable under the ESCOREZ serles reslhs rrom Ex~on
Chemlcal Company. ~ preferred tacklrylng resin Or the
ESCOREZ serles ls ESCOREZ 5300 resin. Thls resln has a
water whlte color (Color aardner No. Or 3 or less); a Ball
and Rlng sortenlng polnt Or about 105C; a speclrlc
gravity (60/60F) Or 1.10; a Brookrleld vlscoslty (70
percent ln toluene at 60F) Or about 130 centlpol~e; and
a fla~h polnt (COC) Or about 210C.
~ c~é,ro~
12738Sl
18
An alternative pr~ferred ESCOREZ re~in having a
somewhat higher ~ortenlng point is ESCOREZ'5320 resln.
The latter resin has a water white color (Color aardner
No. of 3 or less); a Ball and Ring sortening point Or
about 125C; a speairlc gravlty (60/60~) Or 1 10; a
Brookrield viscoslty (70 percent ln toluene at 60F) Or
about 350 centipoise; and a rlash point (COC) ~r about
243C. ~n alternatlve p~eferred tackirying resin is a
transparent nonwax hydrogenated hydrocarbon resin rormed
Or styrene monomer which is polymerlzed and subsequently
rully hydrogenated. A re~ln ~r thls latter type 18
avallable under the nEaAL~EZ tradename from llercules
,,
Chemlcal Company. A speciflc REaAL~EZ resln round to be
partlcularly suitable ror use as the tacklrylng re~ln ln
the present lnvention 18 REa~LREZ 1126, whlch has a
crystal clear color; a Ball and ~lng sortening point Or
between about 122C to 130C; a speciric gravit,y at
21C Or o 97; an acld number Or less than 1-0; and a
melt vlscosity Or 1 poise at 209C and 10 polse at
182C; and a rlashpolnt (COC) Or 243C.
The use Or a tacklrylng resin from the above-
descrlbed classes ln appll¢ant's hot melt rormulation rOr
wax release layer 20 has an addltlonal advantage over
aonventlonal resins such as pentarerythrltol ester Or
hydrogenated rosln used in prior art wax release
formulatlorls. Such reslns may oxidlze over a period Or
tlme causing a dulllng erfect ln the appearance Or the
transrerred deslgn lmage. In contrast, the tacklrylng
reslns employed ln the present rormulatlons for release
3~ layer 20 do not o~ldlze wlth tlme after the substrate 15
has been transrerred onto an artlcle.
The parafrin wax aomponent Or the formulation ror
release layer 20 18 used to glve layer 20 lts pr,inclpal
..... . .
.
: ' ''
. ~
lZ738~1
release characteristic upon meltlng. Pararrin wax, a
petroleum derived product, typlcally ha~ a molecular
welght between about 25l1 to 450 and i8 composed
essentially Or linear saturated hydrocarbons ranging from
C181~38 to C32ll66 Pararflns typlcally have a
meltlng polnt from about 110 to 150F. ("Meltlng polnt"
as uced herein refer~ to drop melting point). A Preferred
parafrin wax ror use in the rormulation Or the present
lnvention is composed Or llnear saturated hydrocarbons
ranglng from C26ll51l to C32~i66 havlng a meltlng
polnt between about 145F to about 155F.
The pararrin wax, a llnear saturated hydrocarbon, ls
characterlzed ln that lt crystalllzes in both plate and
needle-type crystals, partlcularly the rormer. ~nother
type Or crystalllne structure, termed malcrystalllne, 18
nelther plate nor needle-like and 18 observable ln the
parafrln crystal structure ln amount dependlng on the
bolllng polnt Or the pararfln rractlon belng lnvestlgated.
In parafrln wax rractlons Or lower bolllng point, for
example about 1~0~ at 10 mm pressure, the entlre
¢rystalline structure is composed Or plates. ~n pararrln
wax rractions having somewhat higher boillng points, a
mlnor amount Or malcrystalllne and needle-llke structures
mag be observable interspersed among the plate-llke
structures. In general, the plate crystals predominate in
pararrin waxes Or any bolllng range. Ilowever, ln the
hlgher meltlng pararrln waxes where there is likely to be
some increased amount of branchlng associated with their
structure, there 18 llkelg to be a greater portlon Or
malcrystalline and needle-like crystals lnterspersed among
the plates. m e tgpe and amount Or crystals round ln
parafrln wax is principally an inherent runction Or the
boillng polnt range Or pararrlns being investigated
lrrespective Or the solvent or medlum used from which the
crystalllne solld 18 preclpltated.
'
', ' ~ '
.
'
.
1~73851
Parar~in wax suitable for use ln release layer 20
18 sold in varlous grades which dlrfer chierIy in melting
point. Commerclal grades Or parafrin wax whlch may be
used in release layer 20 are commonly designated a~
rerlned~ semire~ined, and crude grade waxes. or these the
rerlned grade i~ prererred for use in the present
formulation rOr release layer 20. Parafrin wax Or rerlned
grade is obtainable from a number Or source~, one Or which
is the Petrolite Corp., Bareco DiYisionJ Or Tulsa,
Oklahoma.
The miGrocrystalline component Or rormulatlon 20 is
composed Or saturated hydro¢arbons Or higher melting point
than those Or pararfln wax. Micro¢rystalline waxes
chara¢teristlcally contain between about C341170 to
C60~1120 hydro¢arbons having molecular weight between
about 478 and 840. Microcrystalline waxes (mlcro-waxes)
are characterized by an lncreased amount Or branchlng;
although they contain straight ohain molecules, they are
- not as linear a saturated ~ydro¢arbon as pararrin wax.
Also compared to pararrin wax, they contain a greater
portlon Or cyclic ring molecules. The crystalline
structure Or the microcrystalllne wax contains
predomlnantly malcrystalllne and needle-like crystals
havlng very small underlned form when compared wlth the
plate-llke crystalllne structure Or pararrin wax under the
same magnificatlon. Thus the crystalllne structure Or
mlcrocrystalline wax 18 small and irregular when
; solldlrled rrom the melted wax. In solvents
mlcrocrystalllne wax dlscloses no well-rormed crystals Or
any size. Small amounts Or mlcrowax are advantageously
added to the formulatlon ror release layer 20, slnce
mlcrQwax lmparts a measure Or plasticity to the pararrin
wax componente, clnco tho pararrln wqx 1~ rather brlttle
.
'
1273851
21
and would by itself tend to cause cracks or fissures in a wax
release layer. Because of its diminished crystalline
structure, microwax contributes little potential hazing or halo
effect.
The classes of microwaxes vary principally in their melting
point range. For example, the so-called hard microwaxes have a
melting point between about l9o to 210F; the plastic
mircowaxes a melting point between about 145 to 175F; the
emulsifiable crystalline waxes between about lso to 225F; and
modified microwaxes between about 165 to 220F. All of these
various types of microwaxes may be employed in the present
formulation; however, the plastic type (BAREC0 designation) is
most preferred. An illustrative, commercially available
microcrystalline wax which is particularly suitable in the
present formulation is available under the Victory White
tradename from the Petrolite Corp.
The montan wax component for release layer 20 iS a coal
(lignite) derived wax characterized by high concentration of
montanic acid (C"H~60~). Montan wax has been determined to be a
very suitable additive to increase the hardness of release
coating 20, as well as its lubricity. Additionally, montan wax
promotes a smooth glossy texture of the release coating after
transfer. Montan wax also prevents penetration of the release
coating into the paper carrier 10, as it forms a formation of a
hard protective barrier coating over the transferred design
layer.
A particularly suitable type of montan wax is an oxidized,
esterified, partially saponified montan wax as disclosed in
U.S. Patent 3,616,015. Montan waxes of this type have melting
points (drop points) typically between about 50 and 110C,
.
,
, ' ' . ' ' , .
1273851
saponiflcation value~ ~etween about 25 ~nd 150, acid
values between about 5~ and 40, and penetrometer hardnes~
(ASTM-D5-52) below about 15 as measured with 100 grams
for 5 second~ at 25C. The~e montan waxes also have
5 relatively hlgh melt vlscoslty. An lllustratlve oxldlzed,
esteriried~ partlally saponlrled montan wax is avallable
under the tradename ~loech~t OP or Hoech~t X55 modlried
montan wax from the Hoechst Chemical Company, (location).
I50ech~t OP modlried montan wax has a drop polnt
10 (ASTM D12l) Or 212 to 221~, a congealing point
(ASTM D938-49) between 165 and 175F, an acld number Or
1~ to 15, and a ~aponirication number Or 100 to 115.
Iloe¢hst X55 has a drop polnt of 20~ to 218F, a
congealing polnt Or 167 to 176~, an acid number Or 10
15 to 15, and a saponlrlcation number Or 90 to 110. The~e
waxes have melt viscoslties Or at least about 150
centlpolse at a temperature Or about 25F above thelr
solldlricatlon point.
A partlcularly suitable blnder ln the preferred
20 release formulation i8 a copolymer Or ethylene and
vlnyl~¢etate, such as that avallable under the tradename
Elvax 410 ~rom E.I. duPont Company, Wllmlngton, DE. The
blnder 18 used prlncipally to blnd the components Or the
release rormulation trelease layer 20) ln a homogeneous
25 mlxture, whlch rorms a hot melt and does not require a
solvent. The varlous components Or the release
formulation do not copolymerl~e ln any measure durlng the
coatlng stage or durlng meltlng and subsequent
resolldlrlcatlon Or release layer 20. A blnder Or
30 copolymer Or ethylene and vinylacetate such as Elvax 410
18 most preferred because lt provldes hlgh optlmum gloss
ln blends with wax. However, other blnders Or ethylene
and vlnylacetate copolymer, as ror example, ~lvax 210,
. . .
~Z73851
310, may be used. An alternative blnder in the ~LVAX
serles such as Elvax~4310 which 18 ethylene vlnylacetate
acryllc acld terpolymer has also been determined to be
sultable. Also ln place Or the above-referenced blnders
acryllc acid terpolymer has also been determined to be
an ethylene acryllc acld copolymer blnder may be employed.
A sultable blnder Or thls latter type 18 available under
the tradename ~C-540 rrom Allled Chemical Company.
Prererred ¢omposltlons ror release layer 20 are
shown ln Table I. Although spe¢lrl¢ rormulatlons rOr the
release layer 20 are glven ln Table I, lt has been
determlned that the pararrln wax may be present ln release
layer 20 ln an amount between about 15 to 30 weight
percent, prererably between about 20 to 25 welght percent.
me montan wax may be present ln release layer 20 ln an
amount between about 15 to 35 welght percent, and the
tacklrylng resln ln an amount between about 15 to 50
welght percent, prererably about 35 to 45 welght percent.
ffl e weight ratlo Or montan wax to tacklrylng resln may be
ln a range between about 0.3/1 to 2.3/1.
:
'
'
. ~, ,
,, ~,
i ~,
':
. ~
'.' "' ~, ' ' ' ' ' ~
.
~'.' ~ ' ' '. ',
,
~Z7~851
24
T A B L E
F~n~UL~ A B ~ ~
Wt. Wt. Wt. Wt.
Z % %
Pararrin Wax 22 22 22 22
Mlcrocrystalline
Wax: (eg. BARECO
Vlctory White) 4 4 4 4
Montan Wax:
(eg. IJoe¢hst OP
or X-55) 27 27 27 27
Taaklrier Resln:
(~Iydrogena ted
IJydroaarbon Polymer
15 --e.g. ESCOREZ 5300) 41 41
e.g. ESCOREZ 5320 41
e.g. REaALREZ 1126 41
Blnder:
(Ethyleile and Vlnyl-
acetate aopolymer)
ELV~X - 410 6 6 6
ELVAX - 4310 6
_
TOTAL 100 100 lOO lOO
- ~ .
. ' ' ': - '" ~
,
1273851
~ ny of the formulations of Table I can be prepared by
addlng the llsted c~mponents in the proportlons shown to a
sultable heatlng vessel and stirred thereln at a
temperature of about 250 to 280F until a homogeneous
hot melt mixture 18 obtained.
The hot melt is coated preferably by roller or
gravure onto carrler 10 ln any desired slze and pattern,
thus rormlng relea~e layer 20. When aoating wlth the
prererred gravure technique, the thickness is convenlently
adJusted by use Or proper gravure cyllnders. The thlckness
Or coated release layer 20 is preferably less than about
0.001 lnch. Other coatlng technlque~ such as cast
¢oatlng, particularly reverse roller coatlng, letterpres3,
and flexographlc techniques, mag be employed.
Arter coatlng release layer 20 onto carrier 10, the
coating quickly becomes solidifled upon exposure to a
water cooled roller. Upon solidlflcatlon Or release layer
20, an lnk deslgn layer 30 may be applied over thls layer
typically using the same coating technique previously
employed.
The lnk deslgn layer 30 18 preferably applled 80 that
release layer 20 e~tends beyond the deslgn layer. The lnk
deslgn layer 30 may be composed Or any conventlonal lnk Or
any color. The ink may typically include reslnous blnder
bases compatlble with the lnk plgment employed. The lnk
blnder may be selected rrom a wlde varlety Or conventional
reslnous bases such as polyamlde, polyvlnyl chloride,
acryllcs, and polyamlde nltrocellulose.
It 18 advantageous to overlay lnk layer 30 wlth an
adheslve coatlng 40 whlch racllitates transfer Or
substrate 15 to the article to be de¢orated. In this case
1273~51
26
substrate 15 may there~ore typlcally be composed Or
release layer 20, ink~design layer 30 and adhesive layer
40 as illustrated in Figure 2. Adheslve layer 40 may
suitably be composed of a thermoplastlc polyaloide
adhesive. A preferred thermoplastic polyamlde adheslve ls
the reaction product Or a diamine wlth a dimerlzed ratty
acid such as that available under the tradename VERSAMID
900 serles from Henkel Corp. Or Mlnneapolis, Minn. It has
been found advantageous to combine thls polyamlde
constltuent wlth a nltrocellulose base ln adheslve layer
10.
In use, carrler web 10 18 heated to a temperature
typlcally rrom about 375 to 400P, i.e. surflcient to
melt the release coatlng 20. Thls may be convenlently
accomplished by conveylng lamlnate 5 over a hot platen ror
a perlod surrlclent to melt release coatlng 20.
Alternatively the article to whlch lamlnate 5 is to be
applled may be preheated to a temperature surriciently
high to melt release layer 2n as laminate 5 is pressed
agalnst the artlcle.
Lamlnate 5 is applled to the article to be decorated
by presslng the heated lamlnate onto the article 80 that
the topmost lager Or trRnsrer substrate 15, ror example
lnk deslgn layer 30 or optional lager 40 contacts the
artlcle. ~olllng pressure 18 applled over the exposed
surrace Or carrler 10 to erfect transrer Or substrate 15
onto the article. m ereupon carrier 10 18 peeled from
substrate 15 while release layer 20 is in molten state,
leaving substrate 15 permanently arrlxed to the artlcle
with design image clearly vlsible through transrerred
release layer 20. Upon exposure to ambient conditlons for
a short perlod, release coatlng 20 solidiries to a clear,
:
. :
.
1~7~8Sl
~mooth glos~y protective layer over transrerred ink deslgn
lmage 30.
The clarity Or the coatlng 20 over deslgn lmage 30 at
thls polnt in the proceBB 18 dlstlnctly greater than the
clarlty of the transferred release layer at the same polnt
in the process as descrlbed ln U.S. Patent 3,616,015.
Transrerred substrate 15 may optionally be exposed to
postrlamlng to remelt transrerred coating 20 and thus
further improve the clarity and gloss of transrerred
coating 20 and consequently clarlty Or transferred design
image 30. Postrlaming may be accomplished, rOr example,
by exposing the transrerred substrte 15 includlng
transrerred coating 20 to Jets Or hot gas elther as dlrect
ga~ rlame or as hot alr ~ets typlcally at about 300F to
400~ or hlgher ror a perlod surrl¢ient to melt the wax
ln the manner deecribed in U.S. Patent 3,616,015. Upon
exposure to amblent atmosphere, coatlng 20 resolidlrles to
a rllm Or such high degree Or clarltg and transparency
that hazing or halo errects are virtually undetectable by
the unalded eye. The clarlty Or transrerred coating 20
and design image 30 is such that the heat transrerable
substrate herein described may be used to decorate
virtually any plastic or glass article. For example, the
substrate 15 18 well suited to the decoration Or such
materials as polyvinylchloride, polyethylene
terephthalate, polyethylene, and polypropylene.
Although the lnvention has been described within the
context Or particular embodiments for the transrerable
substrate, the invention 18 not lntended to be limlted to
any partlcular composltion or layer structure for the
transrerable substrate. It 18 known that the transrerable
subetrato may contaln other co~tlng lnyer~, for e~mple,
- ' ' ,
- -, -
,
1;~73~Sl
28
a plurallty Or lnk deslgn layers or separate adhesive
layer over the ink design layer as well as barrier type
layers between the ink deslgn layer and release layer.
The inventlon is equally applicable to such varying heat
transrerable ~tructures. It should be appreciated that
the release rormulation Or the inventlon has wide
appll¢ation as a release coating for any heat transrerable
subetrate ln aontact with a support member such as a
carrier web. The lnventlon, thererore, 18 not lntended to
be limlted to the de~cription in the ~pecification but
rather is derined by the claims and equivalent~ thereof.
