JPS61172144A - Protective cover composition of photographic layer - Google Patents

Abstract

PURPOSE:To form a film superior in adhesion to a photographic layer hardenability by using a film composed essentially of a mixture of pentaerythritol triacrylate monomer (PE3A) and pentaerythritol tetraacrylate monomer (PE4A). CONSTITUTION:The film forming cmpsn. contains 100pts.wt. of the monomer mixture A composed of 90-10pts.wt. of PE3A and 10-90pts.wt. of PE4A and 1-10pts.wt. of a photopolymn. initiator, and this sum amounts to at least 40wt% of the total film compsn. When other monomers are used in combination, so long as they do not impair the superior adhesiveness of the the mixture A, flexibility, especially, folding esistance can be effectively enhanced. The mixture A is supplied generally in a liquid state, and it is coated as it is by various coating means to form a film or it is adjusted to an appropriate coating viscosity by adding a proper org. solvent or a proper thickner before coating.

Description

Detailed Description of the Invention (a) Industrial Application Field The present invention relates to a coating composition for protecting a photographic layer, and more specifically, for protecting the photographic layer from discoloration, fading, or scratches that are likely to occur in the photographic layer. The present invention relates to a photocurable coating composition for.

゛ ←）Conventional technology On a support such as a plastic film, glass plate, or paper,
A photographic light-sensitive material, which is formed by forming a photographic layer by coating a light-sensitive emulsion mainly composed of fine grains of silver halide and a gelatin binder, can be used as photographic paper, motion picture film, microfilm, or other types of recording material. It is well known as a material and has been used for various purposes since ancient times. However, while these photographic materials have the advantage of being able to perform excellent recording with high precision, they also have several drawbacks that require improvement. For example, photographic materials that have been recorded are often stored for a long period of time, but they have the disadvantage that their photographic layers are susceptible to discoloration and fading during the storage period. Further, 1. Gelatin, which is a binder component of the photographic layer, has poor abrasion resistance and has the disadvantage that the photographic layer is easily scratched during handling. Furthermore, gelatin has a disadvantage in that it has poor water resistance, and if the surface of the photographic layer becomes dirty, it cannot be wiped with water or washed with water.

Therefore, in order to improve the above-mentioned drawbacks of photographic light-sensitive materials, conventional methods have been used to coat the surface of the photographic layer with various protective films, such as (1) laminating a polyester film on the surface of the photographic layer to prevent discoloration and fading. , a method for preventing the occurrence of defects such as scratches. (2) A paint whose main component is a solution of a methyl methacrylate-acrylamide-acrylic acid copolymer in an organic solvent, or
A method of forming a protective film by applying a composition containing an epoxy-terminated silane compound (see JP-A-54-127319). (c) Problems to be Solved by the Invention However, in the method (1) above, when laminating films, air is likely to be trapped between the film and the photographic layer;
Poor workability. The method (2) requires long drying time to form a film of the paint or composition, and has problems such as extremely poor workability. In order to solve (2), we proposed (Japanese Patent Application No. 59-24355) that a photocurable coating composition using pentaerythritol triacrylate (hereinafter referred to as PK3A) would be suitable. It has been found that a film formed from PE3A exhibits excellent adhesion to the photographic layer and is effective in preventing discoloration and scratching of the photographic layer.

However, it has been found that using only PFi3A as a monomer component has the following problems. This is because coating compositions containing PE3A as a main component will not have sufficient hardness if the amount of ultraviolet rays is reduced.
That is, when a protective coating is applied to a photographic layer, a problem arises in that the curing speed of the coating film is slow. In addition, PE3A is generally obtained by the esterification reaction of pentaerythritol and acrylic acid, but at that time, by-products such as pentaerythritol tetraacrylate (hereinafter referred to as PK4A) are also produced, and purification is required to obtain pure PE3A. It would be advantageous in terms of cost if the mixture of PE3A and PE4A that would be required could be used.

In view of these problems, the inventors of the present invention have developed PE3A.
The present invention was completed as a result of studies to solve the above problems while taking advantage of the advantages of the film formed from the gelatin layer, such as good adhesion to the gelatin layer.

) A means for solving the problem, that is, the present invention, consists of 90-10% by weight of PE3A and PE4
A monomer mixture (A) consisting of 10 to 90% by weight 1
A component obtained by mixing 1 to 10 parts by weight of a photopolymerization initiator to 00 parts by weight is at least 40% by weight of the film-forming components.
The present invention provides a coating composition that protects photographic layers from discoloration, fading, scratches, etc.

(E) Effect The monomer mixture (A) consisting of 90 to 10% by weight of PE3A and 10 to 90% by weight of PK4A used in the coating composition of the present invention has a high adhesion to gelatin, which is a component of the photographic layer. It is an important film-forming component that has the properties of increasing hardness and hardening of the coating film.

PF which is a -component of the monomer mixture (A)! If the mixing ratio of 4A exceeds 90% by weight, the crosslinking density will increase, the bendability will deteriorate, and the adhesion to the gelatin layer will also deteriorate, which is not preferable. PI again! The mixing ratio of i4A is
If it is less than 10% by weight, the curing speed of the coating film will be slow,
Undesirable.

The photopolymerization initiators used in the present invention include benzoin, benzoin ethyl ether, acetophenone, 2,2-jethoxyacetophenone, P-dimethylaminoacetophenone, P-dimethylaminopropiophenone, P, P'
-dichloroi/cyphenon, P, P'-hisdiethylaminobenzophenone, benzophenone, 2-chlorobenzophenone, Michler's ketone, benzyl, benzoin methyl ether, benzoin isopropyl ether, benzoin isobutyl ether, benzoin N-7' thyl ether, benzyl dimethyl ketal, tetramethyl ,
Thiuram heptanosulfide, thioxanone, 2-chlorothioxanthone, methylbenzoylformate, 1-
(4-isopropylphenyl)-2-hydroxy-2-
Methylpropan-1-one, 1-hydroxycyclohexylphenylketone, 2-methylthioxanthone, ? −
Hydroxy-2-methyl-1-phenyl-propane-1
- On, etc., and systems that do not emit odor after curing are particularly good.
Preference is given to using pendiyne ethyl ether, benzophenone, benzoin isopropyl ether, 1-(4-isopropylphenyl)-2-hydroxy-2-methylpropan-1-one, 1-hydroxycyclohexylphenyl ketone.

The amount of photopolymerization initiator added is 1o
.

The amount is in the range of 1 to 10 parts by weight, and if the amount added is less than 1 part by weight, the curing speed will be slow and a large amount of light energy will be required to obtain a sufficiently cured film; If the amount exceeds 10 parts by weight, no significant increase in curing rate will be observed, and the odor of the initiator will remain after UV irradiation.

In the coating composition of the present invention, other monomers may be used in addition to the monomer mixture (A) as a film-forming component within a range that does not impair the excellent adhesion of the monomer mixture (A). preferable. The monomer that can be used in combination is at least one selected from urethane acrylate, epoxy acrylate, and polyester acrylate. The combination of these monomers is effective in improving the flexibility, especially the bending resistance, of the film of the monomer mixture (A) in addition to its excellent adhesion and scratch resistance, and is effective in improving the flexibility, especially the bending resistance, of the film of the monomer mixture (A). Even when the protective film is bent, defects such as cracks and cracks can be prevented from occurring in the protective film. The content of the monomer used in combination is 60% by weight or less, especially 10 to 50% by weight in the film-forming components.
It is preferable to include it within the range of .

Content is 60% by weight! Although the flexibility of the protective coating can be improved, the adhesion to the photographic layer and the curability of the coating deteriorate.

As the content of the monomer used in combination increases, the adhesion of the protective coating tends to decrease, but this decrease in adhesion can be improved by adding a functional group-containing top layer to the composition.

Effective functional groups include hydroxyl group, amine group, carboxyl group, phosphoric acid group, etc. Specific examples of monomers containing these functional groups include 2-hydroxyethyl (meth)acrylate, acrylamide, dimethylacrylamide, (meth)acrylic acid, dimethylaminoethyl (meth)acrylate, diethylaminoethyl (meth)acrylate,
N-vinylpyrrolidone, methacryloyloxyethyl phosphate and the like. When these functional group-containing monomers are added in an amount of 0.5 to 10% by weight, particularly 1 to 7% by weight, to the composition consisting of the monomer mixture (A) and the above-mentioned combined monomers, the adhesion and bending resistance are improved. A film can be formed that fully satisfies both properties.

Naturally, the functional group-containing monomer may be added to a composition containing only the monomer mixture (A) as a film-forming component, in which case the adhesion of the photographic layer to the monomer mixture (A) protective coating The properties become even better.

Various additives can be further added to the composition of the present invention thus obtained. For example, in the composition, 10
Ultraviolet absorbers (by weight, Ciba, Geigy Tinuvin 328, Tinuvin 900, Tinuvin 326)
, Tinuvin 327, Tinuvin P1 Sanol LS292,
Addition of Sanol LS144, etc.) is preferable because it has a particularly excellent effect of preventing discoloration and fading on the photographic layer. Also,
0.01 to 10% by weight of a leveling agent (for example, silicone oil, fluorine surfactant, wax, etc.) in the composition;
The addition of is effective in obtaining a smooth coated surface when the composition is coated. Other additives often used in the field of paints, such as plasticizers, antifoaming agents, surfactants, pigments, dyes, and matting agents to the extent that they do not impair transparency, can be included in conventional amounts. .

Since the composition of the present invention is composed of a mixture of the above-mentioned monomers, it is generally supplied in liquid form. Therefore, the liquid composition can be applied as it is to various coating methods for film formation, but it is preferable to adjust the coating viscosity to an appropriate coating viscosity with an appropriate organic solvent or thickener to suit each coating method.

Examples of organic solvents that can be used include benzene, toluene, xylene, mineral spirits, cyclohexane, tetrahydrofuran, ethyl acetate, butyl acetate, ethylene glycol monoethyl ether acetate, acetone, methyl ethyl ketone, and cyclohexanone. Further, as the thickener, those generally known as thickeners such as metal soap, silicon oxide, wax cellulose resin, etc. can be used.

Formation of a film using the coating composition of the present invention can be carried out by a coating method known per se, such as spray coating, dip coating, roll coating, Clavia coating, flow coating, bar code coating, air knife coating, etc. At this time, the thickness of the coating is not limited, but it can generally be 0.5 to 10 microns, preferably 2 to 5 microns.

The composition of the present invention coated on the photographic layer can be easily cured in a short period of time by ultraviolet light irradiated from a xenon lamp, a low-pressure, medium-pressure or high-pressure mercury lamp, an ultraviolet fluorescent lamp, a carbon arc lamp, a tungsten lamp, etc. I can do it.

(f) Examples Next, the present invention will be explained with reference to examples. Note that all parts and amounts in the examples are parts by weight.

Example 1 A composition obtained by adding 50 parts of PK3A, 50 parts of PK4A, and 5 parts of benzoin ethyl ether as a photopolymerization initiator and mixing them uniformly was developed using Bar Coater N14 (manufactured by Print Instrument Ltd., R., UK). The coating was applied to the surface of photographic paper (Fujicolor photographic paper made by Fuji Photo Film Co., Ltd.) to a thickness of approximately 4 microns, and was applied over a distance of approximately 500 m.
A cured film was obtained by irradiating ultraviolet rays with an energy amount of J/crI.

Nichiban's cellophane adhesive tape was pasted on the resulting cured film, and the adhesive tape was then rapidly peeled off to check for peeling of the cured film. Adhesion tests were repeated three times, but no peeling was observed. It showed good adhesion. Also, place the photographic paper with the cured film on the outside for 20 minutes. Although it was bent 180 degrees around a rod of φ, no defects such as cracks and wrinkles occurred in the cured film at the bent portion, and it showed good bending resistance. Further, even after being left in an environment of 50° C. and 80% R and H for two weeks, no changes such as cracking or discoloration were observed in the cured film.

Examples 2 to 7 Coating compositions were produced in the same manner as in Example 1 using the respective formulations shown in Table 1 below.

Table-1 (Note 1) Manufactured by Dainippon Ink and Chemicals Co., Ltd., Unidic V-
'4402 (Note 2) Manufactured by Nagashio Sangyo Co., Ltd., Denacol DA-9
11 Each of the compositions obtained above was applied in the same manner as in Example 1, and then cured. When the obtained cured film was subjected to the same adhesion test as in Example 1, no peeling was observed in Examples 2 and 7 even after three repeated tests, and in Examples 3 to 6, no peeling was observed after three repeated tests. Slight peeling was observed in repeated tests, but no abnormality was observed in the second test, showing good adhesion. In addition, a bending test similar to that in Example 1 was conducted using a rod of 10 m1φ, but no abnormality was observed and good bending resistance was observed. Furthermore, although water was spilled on these cured films, it was easily wiped off and no abnormality was observed in the photographic layer.

The surface of each cured film was cleaned using a nylon scrubber (Sumitomo 3M Co., Ltd., Scotchbrite).
009/25- pressure 10 times to examine the occurrence of scratches on the surface, no scratches occurred on any of the cured films, indicating good scratch resistance.

Further, although the cured films were left in an environment of 50° C. and 80% R and H for two weeks, no changes such as cracking or discoloration were observed in any of the cured films.

Example In addition to the composition of Example 7, an ultraviolet absorber (Tinuvin 328
) A coating composition to which 5 parts of α was added was applied in the same manner as in Example 1,
Test the cured photo with the Sunshine Weather-Ometer.
When tested for 00 hours, the discoloration and fading of the photographic layer was negligible. On the other hand, considerable yellowing of the photographic layer was observed in the case where no coating composition was applied.

Comparative Examples 1 to 8 Each coating composition was manufactured in the same manner as in Example 1 using the compounding ratio shown in Table 2 below.The resulting composition was applied and cured in the same manner as in Example 1, and then tested. did.

(Leaving space below) (Note 3) Same as (Note 1) (Note 4) Same as (Note 2) (Note 5) 40 parts of adipic acid 71.6 parts of hexanediol 40 parts/20 parts of acrylic acid Type polyester acrylate comparative example The coating film of the composition No. 1 has a higher blending ratio of PE3A, so compared to the coating film of the compositions of Examples 1 to 3, the film thickness was 500 m
When irradiated with ultraviolet light at a low dose of J/c+J, the hardness was low, and scratch resistance tests conducted in Examples 2 to 7 showed scratches, which was problematic in practice.

Since the composition of Comparative Example 2 has a small blending ratio of 1K3A,
It peeled off after one adhesion test.

In Comparative Examples 3 to 5, the Pli:4A component of Example 4.57 was changed to PE3A, but when compared with each other, the hardness of the coating was inferior, and as a result of the scratch resistance test, it was found that the coating was scratched. there were.

The compositions of Comparative Examples 6 to 8 are all monomer mixtures (A)
Because the adhesive was not used, it peeled off after one adhesion test.Furthermore, in Comparative Example 9.8, scratches were noticeable in the scratch resistance test, making it impractical.

(G) Effects of the Invention Since the coating composition of the present invention contains the monomer mixture (A) as an essential film-forming component, it forms a film with excellent adhesion to the photographic layer and curability of the film. I can do it. In other words, by forming a film with good adhesion to the photographic layer, it has the ability to protect the interface of the photographic layer for a long period of time, making it extremely effective in preventing discoloration and scratches. It is effective. Furthermore, since the coating is cross-linked by ultraviolet irradiation, it is not only water resistant, but also has excellent solvent and chemical resistance, so various stains can be easily wiped off, and the initial state is always maintained. This has the advantage of allowing images to be stored in their original state for a long period of time.

Furthermore, PE4A contained in the monomer mixture (A) increases the hardness even with low doses of ultraviolet light, increasing productivity and making it possible to use a mixture of PK3A and PE4A, which is advantageous in terms of cost. This is an extremely good composition.

Claims (1)

[Claims] Pentaerythritol triacrylate monomer 90~
A monomer mixture (A
) A protective coating composition for a photographic layer, which contains at least 40% by weight of the film-forming components, which is a mixture of 1 to 10 parts by weight of a photopolymerization initiator per 100 parts by weight.