Retouchable mat film

A retouchable mat film comprising a hydrophobic support which has formed thereon a mat layer containing silicon dioxide as a matting agent is disclosed. The mat layer further includes a mixture of poly(methyl methacrylate) or a copolymer containing at least 80 wt % of methyl methacrylate and a hydrophilic polymer as a binder. This mat film withstands several retouching operations in ink.

FIELD OF THE INVENTION 
The present invention relates to a retouchable mat film and, more 
particularly, to a retouchable mat film which has a mat layer on either or 
both surfaces of a hydrophobic support and wherein letters can be written 
into or erased from the mat layer(s) or a wash-off relief image formed on 
said layer(s). 
BACKGROUND OF THE INVENTION 
Mat films consisting of an inflexible hydrophobic support and an overlying 
mat layer containing a matting agent such as silicon dioxide, titanium 
oxide or glass powder are directly used for drawing purposes or coated 
with a photosensitive emulsion layer to form a wash-off photographic 
material which is exposed in a selected image area, developed and has the 
non-image area subsequently washed off. 
In order to be used for these purposes, mat films are especially required 
to have the following features: 
(1) They have high tensile strength, tear strength and bending strength, no 
tendency of curling and are dimensionally stable against changes in 
temperature and humidity; 
(2) letters can be easily written into the mat films in drawing ink or with 
a pencil and they can be easily erased from the mats; 
(3) letters can be rewritten in the retouched area in drawing ink or with a 
pencil a number of times. 
Various approaches to improve erasability of letters from mat films have 
been considered. For example, Japanese Patent Application (OPI) No. 
53067/81 (corresponding to U.S. Pat. No. 4,366,239) (the term "OPI" as 
used herein refers to a "published unexamined Japanese patent 
application") discloses that such an improvement is achieved by 
incorporating poly(methyl methacrylate) and nitrocellulose in the mat 
layer as binders. Other conventional binders for the mat layer include 
vinylidene chloride copolymers (see, for example, British Pat. No. 
1,047,697 (U.S. Pat. No. 3,370,951)); poly(methyl methacrylate) (see, for 
example, U.S. Pat. No. 3,353,958); polyesters or polyester amides (see, 
for example, U.S. Pat. No. 3,627,563); acetyl cellulose (see, for example, 
Japanese Patent Publication No. 48844/74 (U.S. Pat. No. 3,615,554)); and 
cellulose esters and polyesters (see, for example, Japanese Patent 
Publication No. 39414/74). After letters written in drawing ink on the mat 
layer containing these binders were erased with a rubber eraser, 
frequently, it was not possible to write lines of the desired fineness in 
the erased area because it repelled the drawing ink. 
SUMMARY OF THE INVENTION 
Therefore, the primary object of the present invention is to provide a mat 
layer that can be retouched in ink at least 10 times. 
This object of the present invention can be achieved by a retouchable mat 
film that incorporates in the mat layer a binder made of a mixture of 
poly(methyl methacrylate) or a copolymer containing at least 80 wt % of 
methyl methacrylate and a hydrophilic polymer. 
DETAILED DESCRIPTION OF THE INVENTION 
Suitable methyl methacrylate copolymers are those copolymerized with vinyl 
compounds such as methyl acrylate, ethyl acrylate, butyl acrylate, 
styrene, methyl styrene, chlorostyrene, vinyl acetate, vinyl chloride, 
vinylidene chloride, acrylic acid, acrylonitrile, glycidyl acrylate, 
glycidyl methacrylate and hydroxyethyl acrylate. 
Illustrative hydrophilic polymers are polymers and copolymers containing at 
least 5 mol %, preferably at least 10 mol %, of a vinyl compound having a 
carboxyl group such as acrylic acid or methacrylic acid; cellulose 
derivatives having a carboxyl group such as cellulose acetyl phthalate and 
cellulose acetyl hexahydrophthalate; cellulose ether; polymers and 
copolymers containing at least 10 mol % of a vinyl compound having a 
hydroxyl group such as vinyl alcohol, hydroxyalkyl (meth)acrylate (e.g., 
hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate or diethylene 
glycol mono(meth)acrylate); as well as water-soluble natural polymers such 
as gelatin and starch. Polymers and copolymers of carboxyl group having 
vinyl compounds that are miscible with poly(methyl) methacrylate) and 
derivatives thereof are preferred. (Meth)acrylate means acrylate and 
methacrylate. Accordingly, for example, hydroxyalkyl (meth)acrylate means 
hydroxyalkyl acrylate and hydroxyalkyl methacrylate. 
More specifically, preferred hydrophilic polymers include, but are by no 
means limited to, the following: 
1. Methyl methacrylate-acrylic acid copolymer (83:17 mol %) 
2. Methyl methacrylate-acrylic acid copolymer (88:12 mol %) 
3. Methyl methacrylate-itaconic acid copolymer (90:10 mol %) 
4. Methyl methacrylate-maleic acid copolymer (92:8 mol %) 
5. Styrene-acrylic acid copolymer (85:15 mol %) 
6. Methyl methacrylate-methacrylic acid copolymer (88:12 mol %) 
7. Methyl methacrylate-methacrylic acid copolymer (85:15 mol %) 
8. Ethyl methacrylate-methacrylic acid copolymer (86:14 mol %) 
9. Ethyl methacrylate-methacrylic acid copolymer (83:17 mol %) 
10. Butyl methacrylate-methacrylic acid copolymer (80:20 mol %) 
11. Tert-butyl methacrylate-acrylic acid copolymer (84:16 mol %) 
12. Propylmethacrylate-methacrylic acid copolymer (82:18 mol %) 
13. Styrene-butyl acrylate-methacrylic acid copolymer (45:40:15 mol %) 
14. Styrene-vinyl acetate-methacrylic acid copolymer (40:45:15 mol %) 
15. Butyl methacrylate-2-hydroxyethyl methacrylate copolymer (30:70 mol %) 
16. Butyl methacrylate-2-hydroxyethyl acrylate copolymer (40:60 mol %) 
17. Butyl methacrylate-2-hydroxypropyl methacrylate copolymer (35:65 mol %) 
18. Butyl methacrylate-diethylene glycol monomethacrylate copolymer (45:55 
mol %) 
19. Methyl methacrylate-2-hydroxyethyl methacrylate copolymer (42:58 mol %) 
20. Methyl methacrylate-methacrylic acid-acrylic acid copolymer (84:8:8 mol 
%) 
21. Methyl methacrylate-methacrylic acid-2-hydroxyethyl methacrylate 
copolymer (60:10:30 mol %) 
22. Cellulose acetyl phthalate 
23. Cellulose acetylhexahydrophthalate 
24. Methyl cellulose 
25. Ethyl cellulose 
26. Hydroxyethyl cellulose 
27. Hydroxypropyl cellulose 
28. Methyl methacrylate-vinyl alcohol copolymer (75:25 mol %) 
29. Ethylene-vinyl alcohol copolymer (70:30 mol %) 
30. Vinyl acetate-vinyl alcohol copolymer (30:70 mol %) 
31. Cyanoethyl cellulose 
The mixing ratio of polymethyl methacrylate or methyl methacrylate 
copolymer to the hydrophilic polymer is preferably such that the 
hydrophilic polymer content is 80 to 20 wt %, more preferably 70 to 30 wt 
%, of the total binder. 
Preferred binder mixtures for use in the present invention include a 
mixture of poly(methyl methacrylate) and a hydrophilic polymer, more 
specifically, a mixture of poly(methyl methacrylate) and a methacrylic 
acid copolymer. 
A suitable matting agent for use in the present invention is silicon 
dioxide which may be used in combination with titanium oxide, zinc oxide, 
starch or barium sulfate. Preferred silicon dioxide is "crystalline 
silica" and is commercially available from Tatsumori K.K., Japan under the 
trade name of Crystalite-FM-1 or -VXR. There is no particular limitation 
to the particle size of the matting agent, but the preferred average size 
is from 0.5 to 10.mu., and a 1 to 5.mu. range is particularly preferred. 
Suitable hydrophobic supports for use in the present invention include 
polyester films such as polyethylene terephthalate and polyethylene 
naphthalate films; cellulose ester films such as cellulose acetate and 
cellulose acetate butyrate films; and polycarbonate films. Dimensionally 
stable polyester films, especially polyethylene terephthalate films, are 
used with particular advantage. 
The hydrophobic support is coated with a mat layer formed from a dispersion 
of the binder and the matting agent in a suitable solvent that is prepared 
by agitation with an attritor, sand grinder, homomixer or a ball mill. 
Suitable solvents include ketones such as acetone, methyl ethyl ketone and 
cyclohexanone; esters such as ethyl acetate, propyl acetate and butyl 
acetate; ethers such as dioxane and tetrahydrofuran; alcohols such as 
methanol, ethanol, propanol, butanol and diacetone alcohol; chlorides such 
as methylene chloride, ethylene chloride and propylene chloride; phenols 
such as phenol, cresol and resorcin; methyl cellosolve, ethyl cellosolve, 
methyl cellosolve acetate and dimethylformamide. These solvents may be 
used either alone or in combination. 
The mat layer may contain a coating aid, a cross-linking agent or a 
whitening agent without any resulting disadvantage. A preferred whitening 
agent is titanium oxide having a particle size of 0.1 to 0.5.mu.. The 
coating weight of titanium oxide is preferably from 0.03 to 3 g/m.sup.2, 
more preferably from 0.05 to 2 g/m.sup.2. 
The mat layer may be formed on the support either directly or through a 
subbing layer. The subbing layer may be formed from a coating solution of 
a binder or binders in an organic solvent such as methanol, acetone or 
methyl ethyl ketone. Suitable binders are cellulose esters such as 
nitrocellulose and cellulose diacetate; polyesters; or styrene-butadiene 
copolymers or vinylidene chloride copolymers. The subbing layer may 
optionally contain a swelling agent for a polyester film such as cresol, 
p-chlorophenol or resorcin. 
The mat layer may be applied directly to the hydrophobic support or to a 
subbing layer which is coated on the hydrophobic support by any 
conventional technique such as gravure coating, extrusion coating, dip 
coating, bar coating or roller-bead coating. The drying temperature 
preferably ranges from 50.degree. to 140.degree. C., and the drying period 
preferably ranges from 30 seconds to 10 minutes. The coating weight of the 
matting agent preferably ranges from 1 to 20 g, more preferably from 3 to 
10 g, per square meter. The coating weight of poly(methyl methacrylate) 
preferably ranges from 1 to 10 g, more preferably from 2 to 5 g, per 
square meter. The coating weight of the hydrophilic polymer preferably 
ranges from 0.1 to 8 g, more preferably from 1 to 5 g, per square meter. 
The mat film of the present invention can also be used as the support of a 
wash-off photographic material. The image area (i.e., exposed area) of the 
photosensitive emulsion layer of the wash-off material hardens upon 
development whereas the non-image area (unexposed area) remains 
unhardened. After the development, the non-image area is washed off under 
flowing water to provide the image area in relief. Therefore, the greatest 
feature of the wash-off photographic material is that it is developed with 
a tanning developing agent that hardens only the exposed area. The tanning 
developing agent may be incorporated either in the photographic material 
or in the processing solution. 
Illustrative tanning developing agents are catechol, 4-phenyl catechol, 
hydroquinone, pyrogallol, dihydroxybiphenyl and polyhydroxyspirobisindane. 
For more examples, see U.S. Pat. Nos. 2,592,368, 2,685,510, 3,143,414, 
2,751,295 and 3,440,049. If these tanning developing agents are 
incorporated within the photographic material, their amount preferably 
ranges from 0.005 to 1 mol, more preferably from 0.01 to 0.3 mol, per mol 
of the silver halide in the emulsion layer. The developing agents may be 
added not only to the emulsion layer but also to the adjacent layer. 
The tanning developing agents may be incorporated in the photographic 
material by various methods. One example is to neutralize alkali solutions 
of these agents as taught in U.S. Pat. No. 3,440,049. Another example is 
to disperse the agents in water-soluble organic solvents such as 
cyclohexanone, acetone, methoxyethanol, ethoxyethanol, ethylene glycol, 
dioxane and dimethylformamide. In still another method, the agents are 
dispersed in high-boiling point organic solvents for coupler dispersion 
such as butyl phthalate, dinonyl phthalate, butyl benzoate, diethylhexyl 
sebacate, butyl stearate, dinonyl maleate, tributyl citrate, tricresyl 
phosphate, dioctylbutyl phosphate, trihexyl phosphate and trioctadecyl 
phosphate (see U.S. Pat. No. 3,676,137) or diethyl succinate, dioctyl 
adipate or 3-ethylbiphenyl. A surfactant may be used to help disperse the 
solutions of the tanning developing agents in these solvents in 
hydrophilic protective colloidal solutions, and suitable surfactants are 
saponin, sodium alkylsulfosuccinate and sodium alkylbenzenesulfonate. 
The wash-off photographic material according to the present invention 
comprises the mat film of the present invention that is coated with a 
silver halide emulsion layer as the photosensitive emulsion layer. If 
necessary, the material may also contain an antihalation layer or a 
surface protective layer. Suitable silver halides are silver chloride, 
silver chlorobromide, silver bromide, silver iodobromide and silver 
iodochlorobromide. 
Suitable hydrophilic protective colloids are gelatin, carboxymethyl 
cellulose, polyvinyl alcohol and polyvinyl pyrrolidone. Gelatin is 
particularly preferred, and suitable gelatins are lime-treated gelatin, 
acid-treated gelatin and enzyme-treated gelatin, as well as gelatin 
derivatives. 
The silver halide emulsion layer may also contain an anti-foggant, a 
polymer latex, a surfactant, a chemical sensitizer, a spectral sensitizing 
dye, etc. For details of these additives, see Research Disclosure, 176, 
pp. 22-29, December, 1978. 
The surface protective layer may contain not only the hydrophilic 
protective colloid but also a mating agent, a surfactant, a polymer latex, 
colloidal silica, etc. 
The wash-off photographic material according to the present invention 
preferably has an antihalation layer between the support (i.e., mat film) 
and the photosensitive emulsion layer. The antihalation layer may contain 
not only the hydrophilic protective colloid but also a light-absorbing 
material such as carbon black, colloidal silver, or any of the dyes that 
are listed in Research Disclosure, supra. Carbon black or colloidal silver 
are particularly preferred. For facilitating coating with a hydrophilic 
colloidal layer such as the silver halide emulsion layer or antihalation 
layer, the mat layer may be subbed with a layer that is primarily made of 
gelatin. 
The wash-off material according to the present invention may be developed 
with any known technique. If the tanning developing agent is incorporated 
in the wash-off material, it may be processed in an activator bath. The 
basic composition of the activator bath is the same as the conventional 
black-and-white developing solution except for no developing agent; it may 
optionally contain a pH buffer, an anti-foggant, a development accelerator 
and a water softener. 
The present invention is described in greater detail by reference to the 
following examples which are given here for illustrative purposes only and 
are by no means intended to limit the scope of the invention.

EXAMPLE 1 
A biaxially oriented crystalline polyethylene terephthalate film was coated 
with a solution of the following formulation in an amount of 15 g/m.sup.2, 
and dried at 120.degree. C. for 10 minutes: 
______________________________________ 
Content 
Components (wt %) 
______________________________________ 
Nitrocellulose 0.5 
Metacresol 8.0 
Acetone 42.0 
Methanol 49.5 
______________________________________ 
Three samples of the so treated film were coated with the following 
dispersions of matting agent (a), (b) and (c) in an amount of 40 
g/m.sup.2, and dried at 120.degree. C. for 5 minutes to provide three mat 
films (A), (B) and (C). 
______________________________________ 
Content 
Components (wt %) 
______________________________________ 
Dispersions of Matting Agent (a) 
Poly(methyl methacrylate), 
10 
"Sumipex B-LG" (product of 
Sumitomo Chemical Co., Ltd.) 
Methyl ethyl ketone 47 
Acetone 25 
Diacetone alcohol 10 
Silicon oxide (av. size = 1.5.mu.) 
7 
Titanium oxide (av. size = 0.3.mu.) 
1 
Dispersion of Matting Agent (b) 
Poly(methyl methacrylate), 
8 
"Sumipex B-LG" (product of 
Sumitomo Chemical Co., Ltd.) 
Nitrocellulose, RS 1/2 of 
3 
Daicel Chemical Industries, Ltd. 
Methyl ethyl ketone 46 
Acetone 25 
Diacetone alcohol 10 
Silicon oxide (av. size = 1.5.mu.) 
7 
Titanium oxide (av. size = 0.3.mu.) 
1 
Dispersion of Matting Agent (c) 
Poly(methyl methacrylate), 
6 
"Sumipex B-LG" of Sumitomo 
Chemical Co., Ltd. 
Nitrocellulose, RS 1/2 of 
2.5 
Daicel Chemical Industries, Ltd. 
Methacrylic acid-methyl 
3.0 
methacrylate copolymer (MAA to 
MMA molar ratio = 2:8, 
m. wt. = ca. 10,000-30,000) 
Methyl ethyl ketone 45.5 
Acetone 25.0 
Diacetone alcohol 10.0 
Silicon oxide (av. size = 1.5.mu.) 
7.0 
Titanium oxide (av. size = 0.3.mu.) 
1.0 
______________________________________ 
Letters were written into the mat surface of each sample in drawing ink, 
erased with a rubber eraser and the same letters were written on the 
erased area. On the second trail of retouching, Samples (A) and (B) 
repelled the applied ink and gave only very thin lines. Sample (C) 
withstood 10 retouching operations and produced lines of the desired 
fineness. 
EXAMPLE 2 
(1) Preparation of a Support 
A biaxially oriented crystalline polyethylene terephthalate film 100.mu. 
thick was coated with a solution of the following formulation in an amount 
of 10 g/m.sup.2 and dried at 120.degree. C. for 5 minutes. 
______________________________________ 
Content 
Components (wt %) 
______________________________________ 
Cellulose acetate 
0.4 
Nitrocellulose 0.4 
Acetone 50.0 
Resorcin 6.2 
Methanol 43.0 
______________________________________ 
The so treated film was coated with the following dispersion of matting 
agent in an amount of 50 g/m.sup.2 and dried at 120.degree. C. for 10 
minutes. 
______________________________________ 
Content 
Components (wt %) 
______________________________________ 
Poly(methyl methacrylate), 
7 
"Sumipex B-LG" of Sumitomo 
Chemical Co., Ltd. 
Nitrocellulose, RS 1/2 of 
3 
Daicel Chemical Industries, Ltd. 
Methyl methacrylate-methacrylic 
4 
acid (85:15 mol %) copolymer 
Diacetone alcohol 15 
Acetone 47.5 
Methanol 11 
Silicon oxide (av. size = 1.5.mu.) 
12 
Titanium oxide (av. size = 0.3.mu.) 
0.5 
______________________________________ 
The resulting mat layer was further coated with the following solution in 
an amount of 10 g/m.sup.2 and dried at 120.degree. C. for 10 minutes. 
______________________________________ 
Content 
Components (wt %) 
______________________________________ 
Gelatin 1.0 
Polyamide epichlorohydrin 
0.02 
resin described in Japanese 
Patent Publication No. 26580/74 
Nitrocellulose 0.5 
Water 2.0 
Acetic acid 2.0 
Methanol 63.48 
Acetone 30.0 
______________________________________ 
(2) Preparation of a Wash-Off Photographic Material 
An emulsion containing 60 g of gelatin and 1.1 mols of silver chlorobromide 
(silver bromide content: 30 mol %) in 760 g of water was prepared. The 
silver chlorobromide grains had an average size of 0.4 micron. After 
removing soluble salts by a conventional method, the emulsion was 
chemically sensitized with sodium thiosulfate. To the so sensitized 
emulsion, the following composition was added. 
______________________________________ 
Content 
Components (g) 
______________________________________ 
6% Aqueous saponin 
20 
Dispersion (a) 500 
______________________________________ 
Dispersion (a) was prepared by vigorously agitating a mixture of the 
following compositions (a-1) and (a-2). 
______________________________________ 
Content 
Components of (a-1) (g) 
______________________________________ 
##STR1## 17 
##STR2## 3 
##STR3## 7 
Tricresyl Phosphate 18 
Ethyl Acetate 25 
______________________________________ 
Content 
Components of (a-2) (g) 
______________________________________ 
Gelatin 25 
Water 380 
6% Aqueous saponin 25 
______________________________________ 
A composition for antihalation layer was prepared from the following 
formulation. 
______________________________________ 
Components Content 
______________________________________ 
Gelatin 40 g 
Carbon black 15 g 
Water 1,000 ml 
______________________________________ 
The photographic support prepared in (1) was coated with the composition 
for antihalation layer to give a carbon black coating weight of 0.1 
g/m.sup.2. The resulting antihalation layer was overlaid with the silver 
halide emulsion, thereby forming a wash-off material. The material was 
exposed through an optical wedge for 5 seconds and developed in an 
activator bath of the following composition at 20.degree. C. for 10 
seconds. The developed material was then immersed in warm water 
(40.degree. C.) wherein the unhardened area was wiped off with a sponge 
and thereafter the material was dried. 
______________________________________ 
Components of the Activator Bath 
Content 
______________________________________ 
Potassium carbonate 25 g 
Potassium hydroxide 7 g 
Potassium sulfite 1 g 
Potassium bromide 0.1 g 
Water to make 1,000 ml 
______________________________________ 
The mat surface of the non-image area in relief was subjected to 10 
retouching operations with drawing ink; no ink repellency occurred and 
lines of the desired thickness were produced. 
While the invention has been described in detail and with reference to 
specific embodiments thereof, it will be apparent to one skilled in the 
art that various changes and modifications can be made therein without 
departing from the spirit and scope thereof.