Description:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to photographic sensitive materials and particularly to a method of forming photographic images wherein the occurrence of reticulation is very small, high speed processing can be carried out at a high temperaure and anti-adhesive properties are improved.
2. Description of the Prior Art
Exposed photographic sensitive materials are generally processed at 30°C or less. If the temperature of the processing is increased, it becomes possible to shorten the period of time for processing, because the speed of processing, such as development and fixing of the silver halide or the color development thereof, increases with an increase in the temperature. However, if such a rapid processing is carried out, reticulation of the photosensitive materials in the processing solutions at a high temperature and the quality of images obtained after development remarkably deteriorates.
For example, if the material is processed at 49.5°C, conventional emulsion layers are excessively swelled and sometimes the emulsion layer delaminates from the support due to the occurrence of reticulation on the treated film. As a method of solving this problem, the addition of a large amount of a hardening agent to the photosensitive materials has been suggested. However, this method adversely affects the photographic emulsions or delays the speed of processing. Hence, it is necessary to prevent occurrence of reticulation in the processing of photographic sensitive materials and particularly multi-layer color photographic sensitive materials at a high temperature using other methods different from the above described method in which a large amount of a hardening agent is added.
Further, photographic sensitive materials have a surface layer containing a hydrophilic high molecular weight compound such as gelatin as a binder. Therefore, the surface of the photographic sensitive material is easily influenced by the temperature and easily becomes sticky.
For example, when photographic sensitive materials are stored at high humidity and particularly in an atmosphere of a high humidity and a high temperature, they easily stick to each other or to other materials on contact because the adhesivity and stickiness thereof remarkably increase. Such adhesion phenomenon is very disadvantageous because the adhesion is brought about between the photographic materials themselves or between the photographic sensitive material and other materials contacted therewith during production, exposure, processing, projection or storage of the photographic sensitive materials.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a method of forming photographic images wherein the occurrence of reticulation at high temperature processing is inhibited and the anti-adhesive properties are improved.
As the result of much research, the present inventors have found that the occurrence of reticulation in development of photographic sensitive materials at high temperature is mainly due to the surface layer. As the result of their research, the present inventors have found that the occurrence of reticulation is remarkably inhibited and the anti-adhesive properties are improved by adding the following high molecular weight compounds to the surface layer of the photographic sensitive materials.
Namely, according to the present invention, a method of forming photographic images wherein dimensional stability is excellent in a high temperature processing, reticulation does not occur and the anti-adhesive properties are excellent can be provided by using photographic sensitive materials having a surface layer containing a specific high molecular weight compound. Furthermore, it has been found that the occurrence of reticulation can be inhibited in providing such a surface layer, even if high speed drying is carried out at production of the photographic sensitive materials.
The invention provides a method of forming photographic images which comprises developing at a temperature of above 30°C a photographic sensitive material comprising a support having thereon at least one photosensitive emulsion layer and a surface layer comprising a hydrophilic binder and containing a copolymer including repeating units represented by the formula (I) ##SPC3##
and repeating units represented by the formula (II) ##SPC4##
wherein R represents a hydrogen atom or a methyl group, M 1 and M 2 each represents a member selected from the group consisting of a hydrogen atom, a lithium atom, a sodium atom, a potassium atom and an ammonium group, whereby occurrence of reticulation decreases and the anti-adhesive properties are improved.
DETAILED DESCRIPTION OF THE INVENTION
In the following, the present invention will be described in greater detail.
The high molecular weight compounds used in the present invention are those produced by copolymerizing styrene or methyl styrene and maleic acid or maleic acid anhydride and hydrolyzing the resulting copolymer, which have repeating units represented by the following general formulae (I) and (II) ##SPC5##
wherein R represents a hydrogen atom or a methyl group and M 1 and M 2 each represents H, Li, Na, K or NH 4 .
Of course, copolymers having these units can contain, if desired, one or more other polymerizable monomers so long as the hydrophilic properties thereof are not injured. Such polymerizable monomer components include the alkyl esters of acrylic acid and methacrylic acid (e.g., methyl methacrylate, ethyl acrylate, hydroxyethyl acrylate, propyl acrylate, cyclohexyl acrylate, 2-ethylhexyl acrylate, decyl acrylate, β-cyanoethyl acrylate, β-chloroethyl acrylate, 2-ethoxyethyl acrylate, sulfopropyl methacrylate and the like), vinyl ethers (e.g., methylvinyl ether, butyl vinyl ether, oleyl vinyl ether and the like), vinyl ketones (e.g., methyl vinyl ketone, ethyl vinyl ketone and the like), styrene derivatives (e.g., dimethyl styrene, 2,4,6-trimethylstyrene, ethylstyrene, laurylstyrene, chlorostyrene, dichlorostyrene, methoxystyrene, cyanostyrene, dimethylaminostyrene, chloromethylstyrene, vinylbenzoic acid, styrene sulfonic acid, α-methylstyrene and the like), vinyl heterocyclic compounds (e.g., vinylpyridine, vinylpyrrolidone, vinylisoxazolidone, vinylimidazole and the like), acrylonitrile, vinyl chloride, vinylidene chloride, ethylene propylene, butadiene, isoprene, chloroprene, itaconic acid anhydride, citraconic acid anhydride and vinyl sulfonic acid.
In the polymerization reaction, acetone, methanol, isopropanol, methyl ethyl ketone, tetrahydrofuran, dimethylformamide, benzene or a mixture thereof can be used as a solvent. The quantity of the monomers charged can be suitably varied, for example, the monomers can be used in a range of about 20 to 150 percent by weight to the solvent.
As polymerization initiators, conventional radical polymerization catalysts such as azobisisobutyronitrile, 2,2'-azobis-(2,4-valeronitrile), 1,1'-azobis-(cyclohexane-1-carbonitrile), 2,2-azobis(4-methyl-2,4-dimethyl valeronitrile) and benzoyl peroxide can be effectively used. The amount of the catalysts is about 0.1 to 5 percent by weight, and preferably is 0.5 to 2.0 percent by weight based on the weight of the monomers from an operational viewpoint. Further, the polymerization reaction is carried out by heating at about 60° to 80°C in an inert atmosphere, e.g., a nitrogen atmosphere, for about 3 to 6 hours. The produced polymers are used after neutralizing or hydrolyzing with an aqueous alkali solution, such as lithium hydroxide, sodium hydroxide or potassium hydroxide, of a concentration of about 2 to 30 percent by weight, preferably 10 to 20 percent by weight. It is preferred the content of maleic acid in the copolymer range from about 40 to 60 percent on a molar basis, because, the viscosity of a coating solution is too high during the application thereof for forming the surface layer if the maleic acid content is too high, while the compatibility of the copolymer with gelatin deteriorates if the maleic acid content is too low. A suitable amount of the copolymerizable monomer which can be present can range from about 0.5 to 30 mole percent, preferably 1 to 10 mole percent. Although the molecular weight of the copolymers is not limited and can vary widely, copolymers having a molecular weight of about 10 3 to 10 6 and particularly 10 4 to 5 × 10 5 can be suitably used. Suitable polymerization procedures which can be used are well known in the prior art, for example, as disclosed in W. R. Sorensen et al., Preparative Methods of Polymer Chemistry, John Wiley and Sons, New York (1961).
Thus resulting copolymers are used as a component of the surface layer. In adding these copolymers to the surface layer, a preferred amount thereof ranges arom about 5 to 80 percent by weight based on the total weight of the binder in the top layer. Because, if the amount is less than about 5 percent, a sufficient effect can not be obtained and if the amount is above about 80 percent, the surface layer dissolves on development in alkaline developers. A suitable thickness for the top layer generally ranges from about 0.1 to 5μ, preferably 0.3 to 3μ.
By addition of these copolymers to the surface layer, the occurrence of reticulation can be inhibited. However, if these copolymers are used together with matting agents, the anti-adhesive properties can be improved. Accordingly, the surface layer can also contain matting agents such as polystyrene, polymethyl methacrylate, silica, starch powder, zinc carbonate, glass beads, cadmium carbonate, polyethyl acrylates, copoly-methyl methacrylate-butylacrylate, strontium carbonate, magnesium oxide barium sulfate-strontium sulfate, titanium oxide, zirconium oxide a silver halide such as silver bromide, polystyrene, cellulose triacetate, a calcium salt or magnesium salt of an acid such as an aliphatic acid, an aromatic acid, an aromatic dicarboxylic acid such as terephthalic acid, a polycarbonate and the like. The most preferred matting agents are silica, polymethyl methacrylate, a silver halide, and barium sulfate-strontium sulfate. As the matting agents, those having a particle size ranging from about 0.3 to 10μ, particularly 0.5 to 3μ are preferably used. In using these matting agents, they are used in the amount of about 0.1 to 10 percent by weight and preferably 0.5 to 3 percent by weight based on the total weight of the binders in the surface layer.
The binder of the surface layer can be selected, if desired, from synthetic and natural high molecular weight compounds such as gelatin, gelatin derivatives, polyvinyl alcohol, polyvinyl pyrrolidone, polyacrylamide, polyacrylic acid, polyacrylates, casein, agar agar, albumin, alginic acid, carboxycellulose alkyl esters, hydroxyethyl cellulose, carboxyalkyl cellulose and the like. However, gelatin and the derivatives thereof are more preferable.
In applying these hydrophilic high molecular weight compounds with the above described copolymers and the matting agents on the photographic material, water, organic solvents such as methanol, ethanol, propanol, acetone, methyl ethyl ketone, etc., or mixtures thereof are used. However, water is advantageously used.
In addition, hardening agents as described in, e.g., C. E. K. Mees and T. H. James, The Theory of the Photographic Process, 3rd ed., pages 55 - 60, Macmillan Co., (1966) and the hardening agents described in U.S. Pat. No. 3,316,095 are preferably used at application. Of these hardening agents, those of an aldehyde type (including the mucochloric acid type, and the aldehyde precursor type), an active vinyl type, an active halogen type, a carbodiimide type, an isoxazole type, an epoxy type, an aziridine type and an inorganic type provide better results. Particularly, the following hardening agents exhibit particularly excellent results.
Aldehyde type:
Mucochloric acid, mucobromic acid, mucophenoxychloric acid, mucophenoxy bromic acid, formaldehyde, dimethylol urea, trimethylolmelamine, 1,3-bis-[(diallylamino)-methyl]-urea, 1,3-bis-(piperidinomethyl)-urea, glyoxal, monomethylglyoxal, 2,3-dihydro-1,4-dioxane, 2,3-dihydroxy-5-methyl-1,4-dioxane, succinaldehyde, 2,5-dimethoxytetrahydrofuran and glutaraldehyde.
Active vinyl type:
1,3,5-Triacryloyl-hexahydro-s-triazine and 1,3,5-trivinylsulfonyl-hexahydro-s-triazine.
Active halogen type:
2,4-Dichloro-6-(4'-sulfoanilino)-1,3,5-triazine sodium salt, 2,4-dichloro-6-hydroxy-1,3,5-triazine sodium salt and 2,4-dichloro-6-(2'-sulfoethylamino)-1,3,5-triazine sodium salt.
Carbodiimide type:
Dicyclohexylcarbodiimide, 1-cyclohexyl-3-(3-trimethylaminopropyl)-carbodiimide-p-tolue
nesulfonate and 1-ethyl-3-(3-dimethylaminopropyl)-carbodiimide hydrochloride.
Isoxazole type:
2,5-Dimethylisoxazole perchlorate, 2-ethyl-5-phenyl-isoxazole-3'-sulfonate and 5,5'-(p-phenylene)-bisisoxazole.
Epoxy type:
1,4-bis-(2',3'-Epoxypropoxy)-butane and 1,3,5-tricresylisocyanurate.
Aziridine type:
1,6-Hexamethylene-N,N'-bisethyleneurea and 2,4,6-triethyleneimino-1,3,5-triazine.
Inorganic type:
Chromium alum and chromium acetate.
These hardening agents can be added using conventional methods. For example, a hardening agent dissolved in water or an organic solvent is directly added to the composition used to form the surface layer, or a hardening agent is added in a large amount to an another layer so as to diffuse into the surface layer.
Although the amount of these hardening agents depends upon a desired objects, they can be used in the amount of about 2 to about 80 mg and preferably 5 to 20 mg per gram of gelatin.
Furthermore, as coating assistants, sodium dodecylbenzene sulfonate, sodium N-oleyl-N-methyltaurine, sodium 14-p-nonyl-phenyl-5,8,11,14-tetraoxatetradecane sulfonate and N-tetradecyl-N,N-dimethyl-ammonioacetate can be used.
The contents of the high molecular weight compounds, gelatin, the matting agents, lubricating agents, antistatic agents, the hardening agents and the coating assistants in the present invention can be varied over a broad range depending on the requirements of quality and end-use of the photographic sensitive materials. The specific agents and the optimum amounts thereof can be easily determined by persons skilled in the art.
It is important to choose a method of application in order to increase productivity. For example, dip coating, air knife coating, curtain coating and extrusion coating can be advantageously utilized. The top layer of this invention is applicable to black and white, multi layer color, X-ray and the like photographic materials utilizing any layer structure. The top layer can be a surface layer on the photosensitive layer side of the support or a surface layer on the opposite side of the support to the photosensitive layer.
As development processing solutions, any developer can be used if it can reduce halide particles. In the case of black-white development, developers containing polyhydroxybenzenes, N-alkylaminophenols, 1-phenyl-3-pyrazolidones or a mixture thereof can be used. Examples of polyhydroxybenzenes include hydroquinone, pyrocatechol, pyrogallol and the like. Examples of N-monoalkylaminophenols include N-methylaminophenol, N-ethylaminophenol and the like. Examples of 1-phenyl-3-pyrazolidones include 1-phenyl-3-pyrazolidone, 1-phenyl-4,4-dimethyl-3-pyrazolidone and the like. In the case of color development, developers containing p-phenylenediamine derivatives such as 4-amino-N,N-diethylaniline, 4-amino-3-methyl-N-methyl-N-(β-methanesulfonamidoethyl)anil
ine, 4-amino-3-methyl-N-ethyl-N-(β-hydroxyethyl)-aniline and the like can be used as a developing agent.
In the following, examples of the synthesis of compounds are illustrated in detail. Unless otherwise indicated herein, all parts, percents, ratios and the like are by weight.
Synthesis of Compound 1
500cc of p-cymene, 49g (0.5 mols) of maleic acid anhydride, 52g (0.5 mols) of styrene and 0.5g of azobisisobutyronitrile were charged into a 1-liter 3-neck flask equipped with a stirrer, a nitrogen gas inlet and a reflux condenser. After sufficiently replacing dissolved oxygen by nitrogen gas, the mixture was heated to 90° - 110°C for about 6 hours with stirring. The resulting high molecular weight compound was separated by filtration and dried under a vacuum until a constant weight was obtained. As the result of elementary analysis and alkali titration, the resulting high molecular weight compound had a styrene content of 48.7 mol percent. The yield was 96.2g (95.3 percent). Then the high molecular weight compound was hydrolyzed using an aqueous solution of sodium hydroxide to produce a 20 percent solution. The pH was 6.3. As the result of a determination of the viscosity, the solution had a viscosity of ζ sp/c = 0.61 (30°C).
Synthesis of Compound 2
A polymerization reaction was carried out in the same manner as for the above described Compound 1 but 50cc of acetone, 50cc of methanol, 62.4g (0.6 mols) of styrene, 69.6g (0.6 mols) of maleic acid and 1.3g of benzoyl peroxide as a polymerization initiator were used. Namely, the mixture was heated to 60° to 70°C for 5 hours with stirring.
The reaction product was reprecipitated using water and dried in a vacuum until a constant weight was obtained. The yield was 120g (91.0 percent). AS the result of elementary analysis, the compound was found to contain 57 mol percent styrene (C: 69.2 percent). Then the resulting copolymer was neutralized to make a 20 percent aqueous solution. The pH was 6.8 and the viscosity was ζ sp/c=0.49.
Synthesis of Compound 3
50cc of acetone, 50cc of methanol, 62.4g (0.6 mols) of styrene, 116g (1.0 mol) of maleic acid and 1.5 g of benzoyl peroxide as the polymerization initiator were charged into a reactor. After replacing the dissolved oxygen by nitrogen gas, the mixture was stirred at 60° to 70°C for 3 hours. The product was reprecipitated using water and dried in a vacuum until a constant weight was obtained. The yield was 95.2g (54.5 percent). As the result of elementary analysis, it was found to contain 47.5 mol percent styrene. The dried product was neutralized with a sodium hydroxide solution to produce a 20% aqueous solution. The viscosity was ζ sp/c = 0.35 (30°C).
In the following, the present invention will be illustrated in greater detail by reference to the following examples.
EXAMPLe 1
On a triacetyl cellulose base film having a subbing layer, a red-sensitive emulsion layer, an intermediate layer, a green-sensitive emulsion layer, a yellow filter layer, a blue-sensitive emulsion layer and a top layer were formed by application, wherein these layers contained the additives shown in Table 1. However, the top layer was formed by preparing compositions 1, 2, 3, 4 and 5 by mixing gelatin as a binder and Compound 1 so that the ratio of Compound 1 was 0, 20, 40, 60 or 80 percent by weight, adding to the resulting compositions 25 mg of 2,4,6-triethyleneimino-1,3,5-triazine as a hardening agent, and 20 mg of silicon dioxide particles and 20 mg of polymethyl methacrylate particles as matting agents per 1g of gelatin, applying the compositions and drying (the thickness of the top layer after drying being 1 - 2μ).
TABLE 1 ____________________________________________________________
______________ Layer Structure (additives, thickness) Red-Sensitive Green-Sensitive Blue-Sensitive Emulsion Layer Emulsion Layer Emulsion Layer (5μ) (6μ) (5μ) ____________________________________________________________
______________ Color Form- 4-Chloro-N-n- 1-2,4,6-Trichloro- 3-(2,4-Di-amyl- ing Agent dodecyl-1-hydroxy- phenyl-3-(3-(α- phenoxyacetamido)- naphthamide (890) 2,4-di-t-amyl- α-(4-methoxybenzoyl) phenoxy)acetamido) acetanilide (1300) benzamido-5- pyrazolone (760) Spectral bis-(9-Ethyl-5- bis-(9-Ethyl-5- None Sensitizer chloro-3-hydroxy- phenyl-3-ethyl) ethyl)thiacarbo- oxycarbocyanine cyanine bromide isothiocyanate (7.0) (5.5) Stabilizer 5-Methyl-7-hydroxy- Same Same 2,3,4-triazaindolizine (8.0) (8.2) (7.0) Hardening 2,4,6-Triethylene- Same Same Agent imino-1,3,5-triazine (48) (45) (65) Coating Sodium dodecylbenzene Same Same Assistant sulfonate (45) (50) (70) Sodium nonylphenoxy- Same Same polyethylene oxypropane sulfonate (60) (70) (90) ____________________________________________________________
______________ Note: The figures in parentheses mean mg per square meter.
Intermediate Layer:
A gelatin solution was applied in a thickness of 2μ so as to include 35 mg of the hardening agent shown in Table 1, 60 mg of sodium dodecylbenzene sulfonate and 75 mg of sodium nonylphenoxy-polyethyleneoxypropane per square meter.
Yellow Filter Layer:
A gelatin solution was applied in a thickness of 2μ so as to include 35 mg of the hardening agent shown in Table 1, 65 mg of the above described coating assistant and 82 mg of yellow colloidal silver per square meter.
Silver Halide Emulsion:
A silver iodobromide emulsion (iodine: 5.5 percent by mol).
After these samples were stored at 25°C and a humidity of 60 percent for 1 week, they were subjected to color negative processing. Then the degree of reticulation was observed on each sample.
In this processing, the temperature was maintained at 25°, 30°, 35°, 40° or 50°C.
______________________________________ Color Development 3' Bleach 6' Water Wash 3' Fixing 6' Water Wash 3' Stabilizing Bath 3' ______________________________________
The compositions of the color negative processing solutions were as follows.
______________________________________ Color Developing Solution: Sodium Sulfate 2.0 g Sodium Carbonate (monohydrate) 30.0 g Potassium Bromide 2.0 g Benzyl Alcohol 5.0 ml Hydroxylamine Sulfate 1.6 g 4-Amino-3-methyl-N-ethyl-N-(β-hydroxyethyl)- 4.0 g aniline Water to make 1 l Bleaching Solution: Sodium Iron-Ethylenediamine Tetraacetate 100.0 g Potassium Bromide 60.0 g Ammonium Hydroxide (28%) 50.0 ml Glacial Acetic Acid 25.0 ml Water to make 1 l Fixing Solution: Sodium Sulfate 10.0 g Sodium Thiosulfate 200.0 g Water to make 1 l Stabilizing Bath: Formalin (40%) 10.0 ml Water to make 1 l ______________________________________
The degree of the occurrence of reticulation of the photographic materials after processing are shown in Table 2.
TABLE 2 ______________________________________ Temperature Temperature and Effect of Treatment Sample No. 1 2 3 4 5 ______________________________________ 25°C A A A A A 30°C C A A A A 35°C C B A A B 40°C C C B A D 50°C C C C B D ______________________________________ In the table, A, B, C and D each are as follows. A Reticulation was not observed at all. B Reticulation was observed slightly. C Reticulation was observed considerably. D The top layer dissolved.
The results in Table 2 show that reticulation occurs with difficulty if a part of gelatin in the top layer is replaced by Compound 1. The greater the amount of gelatin replaced by Compound 1, the less reticulation occurs. However, if excess gelatin is replaced, the top layer easily dissolves. Further, in the case of applying only Compound 1, it is difficult to handle because the compound does not set and the coated layer dissolves during processing.
EXAMPLE 2
Compound 2 was added to each sample of Example 1 as follows, and the samples were produced by application and drying.
Sample 1:
No layers contain Compound 2.
Sample 2:
30 percent in the intermediate layer and the yellow filter layer was replaced by Compound 2.
Sample 3:
30 percent of gelatin in all of the layers except the top layer was replaced by Compound 2.
Sample 4:
30 percent of gelatin in only the top layer was substituted by Compound 2.
Sample 5:
30 percent of the layers was replaced by Compound 2.
After these samples were stored at 25°C and humidity of 60 percent for 1 week, the same processing as in Example 1 was carried out, and then reticulation was observed. The degree of the occurrence of reticulation is shown in Table 3.
TABLE 3 ______________________________________ Temperature Temperature and Effect of Treatment Sample No. 1 2 3 4 5 ______________________________________ 25°C A A A A A 30°C B B A A A 35°C C C C A A 40°C C C C A A 45°C C C C B B ______________________________________ (A, B and C have the same meanings as defined in Example 1.)
From the results in Table 3, it can be understood that the addition of Compound 2 to layers other than the top layer hardly contributed to reticulation inhibition, but if Compound 2 is added to the top layer, reticulation hardly occurs.
EXAMPLE 3
On a polyethylene terephthalate base film having a subbing layer, a red-sensitive emulsion layer, a green-sensitive emulsion layer, a yellow filter layer, a blue-sensitive emulsion layer and a top layer were formed by application using the spectral sensitizers, the stabilizer and the coating assistants shown in Table 1 and 20 mg of mucochloric acid per gram of the binder as a hardening agent. The top layer was formed by preparing samples 1, 2, 3 and 4 by mixing silver halide particles and barium sulfate as matting agents, liwuid paraffin as a lubricating agent and Compound 3 in an amount of 0, 5, 30 or 50 percent by weight based on the binder weight in addition to the above-described coating assistants and the hardening agent, applying the mixture and drying (the thickness of the top layer being 1 - 2μ).
After these samples were stored at 25°C and a humidity of 60 percent for 1 week, the following reversal color processing was carried out by varying the period of time for color processing over a range of 10 to 50 seconds. After processing, the degree of reticulation was examined.
______________________________________ 1. Prehardening 32°C 10-50 Sec. 2. Water Wash " 1 minute 3. Negative Development " 4 minutes 4. Water Wash " 3 minutes 5. Reversal Red Flash Exposure 6. Cyan Color Development " 5 minutes 7. Water wash " 2 minutes 8. Reversal Blue Flash Exposure 9. Yellow Color Development " 5 minutes 10. Water Wash " 2 minutes 11. Reversal Incandescent Exposure 12. Magenta Color Development " 5 minutes 13. Water Wash " 2 minutes 14. Silver Bleach " 5 minutes 15. Fixing " 3 minutes 16. Water Wash and Drying ______________________________________
The compositions of each processing bath were produced using known methods (as disclosed in U.S. Pat. No. 3,723,125).
In greater detail, the composition of the pre-hardening bath was as follows.
______________________________________ Sodium Hexametaphosphate 2 g Sodium Bisulfite 5 g Sodium Pyrophosphate (deca hydrate) 15 g Glauber Salt (anhydrous) 100 g Potassium Bromide 2 g Sodium Hydroxide 0.1 g Formalin (37%) 17 ml Water to make 1000 ml ______________________________________
The degree of reticulation occurrence is shown in Table 4.
TABLE 4 ______________________________________ Time of Time of Processing and Effect Pre-hardening Sample No. (Seconds) 1 2 3 4 ______________________________________ 10 C C C B 20 C C B A 30 C C A A 40 C A A A 50 B A A A ______________________________________
It can be understood from the results in Table 4 that reticulation occurs with difficulty if a part of the binder in the top layer is replaced by Compound 3, even though the time for the pre-hardening treatment is remarkably short,
EXAMPLE 4
In this example, samples corresponding to Sample 1 and Sample 2 of Example 2 were prepared except that silicon dioxide and polymethyl methacrylate particles were not used. Sample 6 and Sample 7 were prepared in the same manner as in Sample 1 and Sample 3 of Example 2.
The resulting Sample 6 and Sample 7 and Sample 1 and Sample 2 of Example 2 were tested with respect to the degree of adhesion. The adhesion test was carried out as follows. Each sample was cut to make two sheets of 2cm × 2cm. These sheets were individually placed at a specific temperature and a specific humidity and were placed so as to not contact each other. After being maintained at such conditions for 2 days, the two sheets of the sample were superposed so that top layer of one faced the back layer of the other. After a weight of 200g was put on the superposed sheets (50g/cm 2 ), the sheets were kept at the same conditions for 1 day. Then the sheets were peeled off and the area of adhesion was measured. In Table 5, the percentages of the area of adhesion based on the total area are shown.
TABLE 5 ______________________________________ Sample Temperature 25°C 30°C ______________________________________ 1 15 50 3 5 10 6 50 90 7 30 80 ______________________________________ Condition: Relative Humidity 90%
From the results shown in Table 5, it cn be understood by comparison of Samples 1 and 3, of Samples 6 and 7, of Samples 1 and 6 and of Samples 3 and 7 that (1) the anti-adhesive property is improved if a part of gelatin in the top layer is replaced by Compound 1 and (2) the anti-adhesive property is remarkably improved if matting agents are additionally added thereto.
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.