JPS5911099B2 - Coated plastic film substrate - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION 25 This invention relates to coated film substrates suitable for photographic emulsion coating.

The adhesive strength of photographic emulsions applied directly to the surface of plastic support films is generally insufficient to withstand the conditions in which photographic films are handled and processed.

Therefore, in order to obtain sufficient adhesive strength, it has become common practice in the photographic art to interpose two or more subbing layers between the support film and the photographic emulsion. In a typical conventional photographic film, a copolymer undercoat layer and a gelatin-containing undercoat layer are provided in order from the support to the outer layer, and a light-sensitive photographic emulsion such as a silver halide-containing gelatin emulsion is coated with the gelatin. 1 is generally bonded to a woo-containing undercoat layer.

It is obvious that there would be benefits such as simplifying the coating process if one or more subbing layers could be omitted, but we are not aware of any commercially successful cases. In accordance with this invention, it has been found that photographic emulsions bond directly to a particular class of subbing copolymers without the need for an intervening gelatin-containing subbing layer. According to the invention, a coated film substrate suitable for photosensitive photographic emulsion coating comprises a self-supporting plastic film and a copolymer undercoat layer applied to at least one surface thereof; The combined undercoat layer contains 35 to 55 mol% of a lower alkyl ester of acrylic acid (the number of carbon atoms in the alkyl group is 8 or less) and 35 to 55 mol% of a lower alkyl ester of methacrylic acid (the number of carbon atoms in the alkyl group is 8 or less). and 1 to 15 mol % of itaconic acid, a half ester of itaconic acid, or itaconic anhydride, and the dry coating weight is 0.05 to 3. 00▼/DTrI.

According to the present invention, the light-sensitive photographic emulsion can be directly adhered to the copolymer subbing layer. That is, proper emulsion adhesion is achieved by bringing the photographic emulsion layer into face-to-face contact with the copolymer subbing layer under conditions customary for handling and processing photographic film. In this case, there is no need to interpose a gelatin subbing layer or to carry out a surface modification treatment of the copolymer subbing layer such as a corona discharge treatment as described in British Patent Specification No. 1,259,506. Self-supporting plastic films can be constructed from cellulose esters such as triacetylcellulose or from suitable thermoplastic films such as polysulfone, polystyrene and linear polyester films.

The linear polyesters include terephthalic acid, isophthalic acid, phthalic acid, 2, 5, 2, 6 and 2, 7 naphthalene dicarboxylic acids, succinic acid, sebacic acid, adipic acid, azelaic acid, diphenyldifulvic acid, One or more dicarboxylic acids or lower alkyl diesters thereof, such as hexahydroterephthalic acid or bis-p-carboxylphenoxyethane, optionally with a monocarboxylic acid such as pivalic acid, and ethylene glycol. , 1,3-propanediol, 1,4-butanediol, neopentyl glycol and 1,4-cyclohexanedimethanol. Biaxially oriented and heat set films of polyethylene terephthalate are particularly useful in making photographic films in accordance with the present invention. Such self-supporting thermoplastic films can be transparent and optically transmissive, and may optionally contain photographically inert dyes, such as blue dyes for X-ray films, and may contain pigments or fillers. It can also be rendered opaque by the addition of additives such as one and may have a white paper-like composition, which can be achieved in particular by the addition of suitable fillers and/or void formation. . The white, paper-like film can be used as the basis for photographic prints. Films suitable for use in instant photography may be black with carbon black particles. Lower alkyl esters of acrylic acid and methacrylic acid as comonomers of the basecoat copolymer include methyl, ethyl, propyl, isopropyl, butyl, pentyl, hexyl, heptyl,
n-octyl and 2-ethylhexyl esters,
Preferred esters are ethyl acrylate and methyl methacrylate.

Itaconic acid is particularly useful as a third comonomer.

Half esters of itaconic acid, in which one carboxylic acid group is esterified, are also useful comonomers. The use of itaconic acid, a half ester of itaconic acid, or itaconic anhydride as a comonomer in the basecoat copolymer not only provides the desired adhesion for the photographic emulsion applied to the basecoat copolymer, but also provides the desired adhesion properties for the application of the basecoat composition. Wetting of the plastic film at the time of application is also improved. When preparing a basecoat copolymer from a molar excess of itaconic acid, a half-ester of itaconic acid, or an itaconic acid anhydride-containing comonomer mixture such that free unpolymerized acid, half-ester, or anhydride is present in the basecoat layer, Stronger adhesion of the light-sensitive photographic emulsion to the subbing layer is obtained.

Strong dry adhesion is obtained with 1.0% by weight or more of free itaconic acid, half ester of itaconic acid, or itaconic anhydride, based on the weight of the copolymer. The basecoat copolymer may be derived from four or more comonomers if desired, and additional comonomers may be used to modify properties such as dry adhesion.

The amount of comonomer present in the copolymer is 8 mole percent or less. Suitable additional comonomers include acrylamide, methacrylamide, N-methylolacrylamide, N-ethanolacrylamide, N-propanolacrylamide, N-methylolmethacrylamide, N-ethanolmethacrylamide, N-methylacrylamide, There are tertiary-butyl acrylamides, nitriles and amines. The nitriles include acrylonitrile, halo monosubstituted acrylonitrile and methacrylonitrile, and the amine includes dimethylaminoethyl methacrylate. Lower alkyl ester of acrylic acid 35
A proportion of from 35 to 55 mol % and from 35 to 55 mol % of lower alkyl esters of methacrylic acid is effective to provide satisfactory adhesion to light-sensitive photographic emulsions; anything lower or higher than this will result in poor adhesion. .

The preferred proportions of 42 to 50 mole % lower alkyl esters of acrylic acid and 44 to 55 mole % lower alkyl esters of methacrylic acid provide optimum adhesion to conventional photographic emulsions. Ethyl acrylate and methyl methacrylate are particularly effective comonomers and provide satisfactory priming properties when copolymerized together with itaconic acid. Ethyl acrylate 43 has particularly advantageous priming properties and exceptional adhesion to photographic emulsions.
45 to 50 mol% of methyl methacrylate
3 mol % and 4 to 10 mol % itaconic acid. The basecoat copolymer can be prepared by conventional emulsion polymerization methods in water in the presence of a suitable emulsifier or mixture of emulsifiers.

The total amount of emulsifier can affect the adhesion of the photographic emulsion to the copolymer subbing layer. The amount of emulsifier is therefore less than 5% by weight, preferably about 4% by weight, based on the total weight of the copolymer. Surfactant based on unbranched sodium dodecylbenzene sulfonate (trade name: Nansa) 1
106, manufactured by Albright & Wilson Co.) provides particularly good adhesion to photographic emulsions.
The photographic emulsion may be used in combination with other emulsifiers, if desired. Conventional additives such as adhesion promoters, slip agents, and antistatic agents may be added in small amounts (e.g., up to 10% by weight based on the weight of the basecoat copolymer), since large amounts may have an adverse effect on the adhesion of the photographic emulsion. ) may be included in the copolymer basecoat composition. When the self-supporting thermoplastic film is an oriented film, such as a biaxially oriented film of polyethylene terephthalate, the basecoat composition may be applied before, during or after the stretching operation used to effect the orientation.

A convenient method is to coat the film between two stretching operations applied to orient the film perpendicular to each other. This improves the adhesion between the film and the undercoat layer. The operation of applying the primer composition is
It may be any known coating method such as dip coating, bead coating, inverted roller coating, air knife, direct gravure or slot coating and the composition may be applied as an aqueous latex or solution or as a solution in an organic solvent. The pH of the undercoat composition is preferably 2.0 to 5.0, more preferably 2.5 to 3.0.

Coverability is excellent at high pHs such as up to 7, but a satisfactory combination of adhesion and coverage is found between 2.5 and 3.

It has been found that this can be obtained at a pH of 0.

Preferably, the basecoat copolymer constitutes 2 to 10% by weight, particularly 5% by weight of the basecoat composition. This is because compositions at such concentrations dry slowly and provide uniformly coated subbing layers with particularly satisfactory adhesion to photographic emulsions. The coating weight for optimal adhesion of the dried copolymer subbing layer to the photographic emulsion is 0.
05 to 3.00 m9/DTrl, preferably 0.5 to 1.00 m9/Dml.

Such coating weights can be achieved by appropriate modification of the basecoat copolymer concentration and/or coating conditions.
A copolymer subbing layer applied in accordance with the present invention to a linear polyester film, such as a polyethylene terephthalate film, is a polyethylene film that supports the copolymer subbing layer rather than the light-sensitive photographic emulsion. Such as may be suitable for circulation from film forming extruders and drawing equipment.

A suitable light-sensitive photographic emulsion, such as a conventional gelatin silver halide emulsion, can be applied directly to the subbing layer by conventional methods. Other light-sensitive emulsions based on binder resins other than gelatin, such as those described in U.S. Pat. No. 4,033,772, are also applicable with excellent adhesion to the subbing copolymer layer of the present invention. Such emulsions may contain conventional additives. It has been found that the light-sensitive photographic emulsion adheres with good adhesion after being applied directly to the surface-modified layer. Light-sensitive photographic emulsions, such as conventional gelatin silver halide Adheres to polymeric subbing layer. The tests referred to herein are conducted as follows.

Adhesion of gelatin-silver halide emulsions through copolymer subbing layers to self-supporting thermoplastic films in the final photographic film after incubation for 16 hours at 50° C. and 75% relative humidity by dry adhesion. means. This measurement is made by applying self-adhesive tape along the tear edge of the film and quickly peeling the tape from the film before and after processing in standard photographic chemicals. The adhesion of the emulsion was rated on a scale of 1 to 5. Grade 1 indicates that no emulsion was removed after removing the adhesive tape 8 times, and Grade 5 indicates that all of the emulsion was removed after removing the tape once. By wet adhesion is meant the adhesion of the gelatin silver halide emulsion via the copolymer subbing layer to the self-supporting thermoplastic film in the final photographic film.

This measurement is made after processing in standard photographic chemicals and washing with water for 15 minutes by rubbing with a sponge over a series of lines scored in a wet emulsion of steel. The adhesion of the emulsion was rated on a scale of 1 to 5. Grade 1 indicates that the emulsion did not come off even after 10 rubbings over the grain line, and Grade 5 indicates that all the emulsion came off after 10 rubbings. The invention will be explained in more detail by the following examples. EXAMPLES 1-19 The basecoat compositions of each example were prepared in batches by conventional emulsion polymerization in water.

Table 1 shows the comonomers and other polymerization components and amounts used.
3 to 3 are shown together with the amount of unpolymerized acid (expressed in % based on the copolymerized weight) and the pH of the latex. A polyethylene terephthalate film was melt extruded and quenched on a cooling rotating drum to an amorphous state.

Claims (1)

[Scope of Claims] 1. A plastic film substrate coated with a coating suitable for light-sensitive photographic emulsion coating consisting of a self-supporting plastic film and a copolymer undercoat layer applied to at least one surface thereof, comprising: Copolymer undercoat layer is 35 to 5
5 mol% lower alkyl ester of acrylic acid (the number of carbon atoms in the alkyl group is 8 or less), 35 to 55 mol% lower alkyl ester of methacrylic acid (the number of carbon atoms in the alkyl group is 8 or less), and 1 to 15 mol% A copolymer prepared from a comonomer mixture consisting of mol % of itaconic acid, a half ester of itaconic acid, or itaconic anhydride and having a dry coating weight of 0.05 to 3.00 mg/d.
A coated plastic film substrate characterized by m^2. 2. A coated film substrate according to claim 1, wherein said self-supporting plastic film comprises a biaxially oriented and heat set film of polyethylene terephthalate. 3. A coated film substrate according to claim 1 or 2, wherein the undercoat copolymer is prepared from a comonomer mixture containing ethyl acrylate and methyl methacrylate. 4 The undercoat layer is 1 based on the weight of the undercoat copolymer.
．． Claim 1 containing 0% or more by weight of free itaconic acid, half ester of itaconic acid or itaconic anhydride
, a film base coated with the coating according to item 2 or 3. 5. The undercoat layer copolymer comprises 43 to 50 mol% ethyl acrylate, 45 to 53 mol% methyl methacrylate, and 4 to 10 mol% itaconic acid. A film base material coated with any one of the above. 6 The dry coating weight of the undercoat layer is 0.5 to 1.0.
Claims 1 to 5 which are 0 mg/dm^2
A film base coated with the coating described in any of the above.