Note: Descriptions are shown in the official language in which they were submitted.
~Z~;~9~5
BACKGROUND OF TIIE INVNTION
The present invention relates to a surfactant which whan used in
combination with a photosensitive resin composition n a high-speed rotary
press printing plate, reduces or prevents contamination. The present invention
is particularly useful with a photosensitive resin composition used to make
a newspaper printing plate.
In the past, the plates generally used in high-speed rotary presses
used by newspapers were metall e.g. lead. In recent years the trend has been
away from such conventional metal plates and towards use of resin based plates.
The resin based letterpress plates are such that a photosensitive resin
composition is irradiated with an actinic light beam through a negative film
to cure the photosensitive resin. Thereafter, a cured resin is developed by
various means, thereby forming a letterpress image. The resin based letterpress
plates are recognized as having advantages because of the increased ease of
handling based on their light weight. Although the resin based plates are
easier to work with, they have the disadvantage of becoming contaminated
; (hereinafter referred to as "contamination") in the dotsl especially on the
photographic face, in the course of printing. Although the mechanism o this
contamination is not fully understood, when this phenomenon occurs ink and
paper dust will accumulate in the valley (concave) portions of the relief plate
and the quality of the normal dot (photograph) is impaired.
In the past, contamination was prevented by separately treating the
resin plates with surface agents which were made by dissolving silicone oil in
~;~ a hydrocarbon solvent or with agents that were water and oil repellent. However,
it was found that agents made by dissolving silicone oil in a hydrocarbon
solvent were not sufficiently durable because they dissolved easily in the ink.
: ~ ~ , .,
~ ~ Case 2735 - 1 -
: ` :
:
~3;~
As a result, contamination occurred after about 20,000 impressions ~ere made.
Further, the latter type of agent is not effective unlcss conlplete heat-curing
is conduc-ted after pre-treating witll the agent. Additionally, even if the
agent is heat-cured its durability is not always satisfactory and contamination
still occurs aftcr printing about 30,000 impressions.
It is an object of this invention to solve the above problems in
resin based letterpress printing plates.
SU~IARY 0~ INVENTION
The p~esent invention prevents or reduces contamination by use of a
photosensitive resin composition which includes about 0.001 to about 5% by
weight of a fluorocarbon surfactant containing perfluoroalkyl groups ~C4-C14).
The surfactant is preferably nonionic. The resin letterpress plate made from
the photosensitive resin composition of the present invention displays a
remarkable contamination preventing effect, i.e. an increase in the number of
impressions that can be made without evidencing any contamination. Use of
the composition of this invention renders quite unnecessary such conventional
operations as preliminary surface treatment. By virtue of use of this
composition it is possible to subject the above letterpress plate to printing
merely by mounting it on a rotary press.
In the present invention the nonionic fluorocarbon surfactant
contains perfluoroalkyl groups (C4-C14) and is preferably contained in a
photosensitive resin composition in amounts of about 0.001 wt.% to about
5 wt.%. If the content is less than about 0.001 wt.%, its effect becomes poor.
If its content exceeds about 5 wt.% it will still be useful but will be less
effective, since its ink repellency becomes too strong with the result that
` ~ the photographic printing effect becomes poor. Additionally, if the content
- 2 -
.
~ ,
~ , ' .
~23~9~;
exceeds about 5% the cost becomes economically disadvantageous.
The fluorocarbon ,urfactant of the present invention is preferably
nonionic. However, it has also been found that an anionic, cationic or
ampholytic fluorocarbon surfactant is also effective to prevent contamination.
However, compounds having these ionic properties are generally not preferred
because it is difficult to maintain their stability with time after they have
been combined with a photosensitive resin composition. In the case of a liquid
photosensitive resin composition, thickening or gellation is likely to occur.
Further, if the photosensitive resin composition is solid such agents are
lt) likely to cause problems such as inability of development.
Examples of the fluorocarbon surfactants used in the present
invention include (2-perfluorooctylethyl polyoxypropylene ether carbamyl)-
polyoxyethylenecarbamyltoluene, 2-perfluorooctyl-1-acetoxymethylethyl
carbamyltolylenestearyl polyoxyethylene carbamate, 2-perfluoroalkyl (C4-C14)
ethanol, 2-perfluorooctyl-1-methylethyl polyoxyethylene ether, perfluoroisop-
ropoxypropylcilsesquinoxane. Of course, the claimed fluorocarbon surfactant
is not restricted by the above examples.
The present invention includes photosensitive resin compositions,
which are liquid or solid at room temperature. A preferred liquid type
photosensitive resin includes predominantly a polyurethane, polyester or
synthetic rubber. Further, a preferred solid type photosensitive resin
includes mainly polyvinyl alcohol or nylon. Of course, neither the liquid or
the solid resin is restricted to the above examples.
The present invention is exemplified by the following l~orking
Examples and Comparative Examples.
~ Example 1
:'
~ - 3 -
, ., :
~: . . .. .
~ . .
:L~3~9~S
60 g of urethane tyye prepolymer obtained by the thermal reaction
of polyoxypropylene glycol (molecular weight of 1000), tolylene diisocyanate
and hydroxyethyl methacrylatc, 35 g of diethylene glycol dimethacrylate and
5 g of pentaerythritol tetrakis (~-lnercaptopropionate) were mixed with 0~5 g of
hydroquinonemonomethyl ether as the thermal polymerization inhibitor and 1 g
of benzoin ethyl ether as the sensitizer. There resulted 101.5 g of urethane
type photosensitive resin composition for letterpress printing.
To this composition 0.5 g of 2-perfluorooctyl-l-methylethyl-
polyoxyethylene ether was added and then mixed. The mixture exhibited good
storage stability. When this mixture was used in a newspaper rotary press,
no contamination occurred until 60,000 impressions were made.
Example 2
To 101.5 g of the same urethane type photosensitive resin as in
Example 1, 0.5 g of (2-perfluorooctylethyl polyoxypropylene ether carbamyl)-
polyoxyethylenecarbamyltoluene, was added and then mixed. The mixture
exhibited good storage stability. I~hen this mixture was used in a newspaper
rotary press, no contamination occurred until 60,000 impressions were made.
Example 3
~ An unsaturated polyester was produced by the thermal reaction of
dimethyl terephthalate, diethylene glycol, propylene glycol, 1,~, 8-
naphthalene tricarboxylic acid anhydride and citraconic acid anhydride. To
70 g of this resin 30 g of acrylamide, 0.01 g of hydroquinone and 0.7 g of
benzoin were added to produce a polyester type photosensitive resin. Further,
0.5 g of the same fluorocarbon surfactant as that in Example 2 was added
to this resin. A printing plate produced using this mixture was used in a
newspaper rotary press and no contamination occurred until 50J000 impressions
were made.
.
:~
~: .
::~
~,Z32g~ S
Example 4
A solid polyvinyl alcohol type photosensitive resin was produced
by mixing 60 g of polyvinyl alcohol, 30 g of hydroethyl methacrylate,
0.1 g of hydroquinone, 5 g of ben~yl dimethyl ~etal and 0.5 g of the
; fluorocarbon surfactant used in Example 2. This blend had good storage
stability. A printing p]ate produced from this mixture was used on a press
; and no contamination occurred until 50,000 impressions were made.
Comparative Example 1
In the case of a urethane type plate prepared without using the
fluorocarbon surfactant of Example 1 contamination occurred at the time
10,000 impressions were made.
Comparative Example 2
In the case of a polyester type plate produced without using the
fluorocarbon surfactant of Example 3 contamination occurred at the time
8,000 impressions were made.
Comparative Example 3
In the case of a polyvinyl alcohol type plate produced without
using the-fluorocarbon surfactant of Example ~ contamination occurred
at the time 8,000 impressions were made.
Examples 5-16 and Comparative Examples ~-7
A printing plate was produced from a composition and used in a
newspaper rotary press, said composition being obtained by mixing each of the
following nonionic fluorocarbon surfactants A-F in fixed amounts with
various resins as shown in Table 1. The number of impressions made without
detection of contamination and the photographic printing effect are shown
in Table 1.
~: ~
- 5 -
. - .:
: : :: , :
~ :
,.
~;~329~
Surfactant
~: 2-perfluorooctyl-1-methylethyl polyoxyethylene ether;
B: (2-perfluorooctylethyl polyoxypropylene ether carbamyl)-
polyoxyethylenecarbamyltoluene;
C: 2-perfluorooctyl-1-acetoxymethylethyl carbamyl-tolylenestearyl
polyoxyethylene carbamate;
D: 2-perfluorooctyl ethanol;
E: perfluorisopropoxypropylcilsesquinoxane; and
F: perfluorooctanesulfonic acid diethanolamide.
-
!:: :
:~j~,, ,. ,: :
~Z329~5
Number of
Impressions Photo
with contami- graphic
. Fluorocarbon Content nation not printing
Ex. No. Surfactant (wt.%) ~-- Resin detected effect
Comp, ~ A 0.0005 Urethane type10,000 Good
; Ex. 4 in Example 1
Ex. 5 A 5 " 65~000 Good
" 6 A 7 " 65,000 Poor
Comp, B 0.0005 " 10,000 Good
Exp 5
Ex. 7 B 5 " 65,000 Good
" 8 B 7 " 65,000 Poor
" 9 C 0.5 " 65,000 Good
" 10 D 0.5 " 60,000 Good
" 11 E 0.5 " 60,000 Good
" 12 F 0.5 " 65,000 Good
" 13 C 0.5 Polyester typeS0,000 Good
in Example 3
" 14 D 0.5 Polyvinyl 60,000 Good
alcohol type
in Example 4
; ~ " 15 E 0.5 Nylon type 60,000 Good
" 16 F 0.5 Synthetic 50,000 Good
rubber type
Comp. Not Used - Nylon type 10,000 Good
Exp. 6
" 7 Not Used - Synthetic 5,000 Good
rubber type
7 -
~23;~9~L5
The nylon type resins, see Example 15 and Comparative Example 6
in Table 1 which comprise 100 wt. parts of a copolymer polyamide of N-bis~2-
aminoethyl)methylamine, adipic acid and ~-caprolactam, 5 wt. parts of methylenel)is
acrylamide, 0.1 wt. part of hydroquinone and 1 wt. part of benzoin. Table 1
shows that when the fluorocarbon surfactant of the present invention is used
as in Example 15, 60,000 impressions were made without detection of contamination,
whereas without the surfactant only 10,000 impressions were made as illustrated
by Comparative Example 6.
The synthetic rubber type resins, see Example 16 and Comparative
Example 1, comprise 100 wt. parts of a styrene-butadiene type block copolymer
(styrene content:35-50 wt.%), 20 wt. parts of 1,6-hexanediol diacrylate, 0.5
wt. part of tertiary butylphenol and 1 wt. part of benzoin ethyl ether. Table
1 shows that when the surfactant of the present invention is used as in Example
16, 50,000 impressions were made with no contamination detected, whereas
without the surfactant only 5,000 impressions were made as illustrated by
Comparative Example 7.
:~
.
,
: :: ~: :: ::
, ,
s:~'j
::
: .: ' : :
~ ~: ::' ': :
