GB2037792A - Subbing liquids for photographic polyester supports - Google Patents

Abstract

The liquids comprise an aqueous composition containing a copolymer of (1) 20 to 55 wt.% of n-butyl acrylate; (2) 35 to 55 wt.% of glycidyl acrylate and/or glycidyl methacrylate, and (3) 10 to 30 wt.% of styrene and/or ???-methyl styrene. When applied to a photographic polyester support a sub layer having improved adhesion properties is obtained.

Description

SPECIFICATION Photographic polyester supports subjected to subbing treatment This invention relates to photographic polyester supports which have been subjected to subbing treatment. Particularly the invention is concerned with photographic polyester supports coated with an aqueous composition containing a copolymer consisting of specific monomers to form thereon a sub layer in order to produce strong adhesion between a photographic composition to be coated on the support and said support when said polyester support is coated with a photographic gelatin composition (for example, a gelatino silver halide emulsion, antihalation agent-containing gelatin composition, gelatin backing composition capable of retaining curl balance of film, gelatin composition to form a second sub layer, etc.).

Polyesters, typical of which is polyethylene terephthalate, are often used as material for preparing photographic supports (hereinafter called "polyester supports") because of their excellent physical properties such as transparency, flexibility and the like. Because of a crystalline structure of polyester, however, the polyester support is high in hydrophobic property and has little affinity for a hydrophobic substance such as a photographic gelatin composition which is intended to be coated on said polyester support.On that account, it is difficult to coat the photographic gelatin composition on the polyester supports, or even when the photographic gelatin composition was able to be coated on the polyester supports, the coated -layer of said composition tend to peel off from the support because of weak adhesion produced between the photographic gelatin comDosition and polyester support.

Accordingly, it has heretofore been practiced to subject polyester supports to subbing treatment prior to coating a photographic gelatin composition on the polyester supports. And, in order to provide the photographic gelatin composition coated on the subbed polyester support as a light-sensitive photographic material to the satisfaction of the end users, it is required to produce and maintain strong, adhesion between the photographic gelatin composition and the subbed polyester support under various circumstances where the light-sensitive photographic material in a wet state during development as well as in a dry state before and after development is subjected to a variety of handlings including mechanical handling. To cope with such requirements, there have heretofore been attempted various subbing processes and a variety of devices for the subbing process.For instance, there are the so-called double layer subbing process in which a layer having good adhesion to a polyester support is formed on the support as a first sub layer and thereon is formed, as a second sub layer, a layer comprising gelatin or hydrophilic high molecular substances, and a monolayer subbing process wherein a polyester support is coated with a monolayer which is a high molecular layer containing a hydrophobic component adhering to the polyester support and a hydrophilic component adhering to a photographic gelatin composition.

Subbing techniques commonly adopted in the photographic industry are disclosed, for example, in U.S. Patent Nos. 3,053,661 and 3,506,445, and Japanese Patent Publications Nos. 18642/1967 and 14434/1973, etc. wherein subbing liquids prepared by dissolving in organic solvents a copolymer having affinity for polyester supports as well as for photographic gelatin compositions and, if necessary, .

adding thereto solvents or swelling agents for polyester supports are coated on the polyester supports for further strengthening the adhesion between the polyester supports and photographic gelatin compositions.

In the subbing processes using compositions containing organic solvents as aforesaid, however, various installations including apparatuses and equipments for recovery of vapors of organic solvents used are required, making heavy investments, in order that during the production step bodies of workers are not exposed to organic solvent vapors harmful to health from the stand point of factory hygiene or discharge of organic solvents in the atmosphere harmful to health of inhabitants from the standpoint of environmental hygiene is prevented. Further, there were some instances where the production operation was greatly restricted due to fire prevention at factory.Furthermore, when solvents or swelling agents for polyester supports were used, there were often brought about such drawbacks that the polyester supports lose their transparency and flatness of the supports is deteriorated and thus the resulting end products are markedly deteriorated in their quality.

Under such circumstances, in recent years there are adopted various subbing processes having overcome such drawbacks as mentioned above, wherein aqueous compositions containing copolymers derived from various monomers are used as subbing liquids. For instance, U.S. Patent No. 3,615,556 discloses a process in which biaxially stretched polyester supports are subbed with aqueous compositions containing butadiene-styrene copolymers comprising acid components. Further, U.S.

Patent Nos. 2,627,088 and 2,698,240 disclose a process in which polyester supports before stretching are subbed with aqueous compositions containing vinylidene type copolymers comprising acid components. Furthermore, Japanese Patent Publications Nos. 13278/1969 and 10988/1970 propose and disclose a process in which biaxially stretched polyester supports are subbed with aqueous compositions containing copolymers of alkyl acrylates and aliphatic bifunctional monomers having 2 allyl groups or 2 vinyl groups.

In the processes in which polyester supports are subbed before stretching or after monoaxial stretching, however, there were involved such practical problems that supports are stretched after subbing, and hence edges of the supports being clamped at the time of stretching cannot be recovered for re-use and production cost sharply increases and so on. Further, even in the processes for subbing biaxially stretched polyester supports, it was difficult to select the kind of copolymer-containing aqueous composition to be used and conditions under which the subbing treatment is effected for imparting excellent adhesive property to polyester support by coating copolymer-containing aqueous compositions thereon, because the polyester supports are of crystalline structure and strongly hydrophobic, with the result that it was difficult to secure sufficiently satisfactory adhesive properties.

On the other hand, there is attempted a process in which polyester supports are first subjected on the surface to surface treatment such as corona discharge or ultraviolet irradiation and then coated on the treated surfaces with subbing liquids. By applying this process to the subbing processes using copolymer-containing aqueous compositions, adhesion between polyester supports and hydrophilic layers to be formed thereon has been greatly improved. It is considered in this connection that the surface treatment referred to above plays a role in forming polar groups on the surfaces of hydrophobic polyester supports or in increasing cross-linkage density of said surfaces, thereby increasing affinity for polar group components contained in subbing liquids, with the result that the adhesion force increases.

As this subbing process, there may be mentioned such technique, for example, as disclosed in Japanese Laid-Open-to-Public Publication No. 1111 8/1 974, wherein a polyester support subjected previously to surface treatment is coated with a copolymer-containing aqueous composition and then the thus subbed polyester support is coated with a photographic gelatin composition. The light-sensitive photographic materials prepared in this manner exhibited excellent adhesive property. With regard to edge peel trouble which exerts a particularly serious influence when development treatment of lightsensitive photographic materials is carried out by means of an automatic developing machine, however, light-sensitive photographic materials comprising a support subbed with a copolymer-containing aqueous composition were found to give unsatisfactory results.The term edge peel as used herein is intended to designated a phenomenon wherein a silver halide emulsion layer or backing layer of lightsensitive photographic material in a wet state during development treatment peels off from the support.

Drawback concretely brought about due to edge peel is such that when a light-sensitive photographic material is developed, for example, by means of an automatic developing machine, the circumferential portion (edge portion) of the photographic material comes to peel off from the support due to rubbing with a transfering rack or rubber roll of the machine, thereby sometimes causing deterioration in quality of the resulting photographic material.

The technique disclosed in Japanese Laid-Open-to-Public Publication No. 104913/1977 is known as a subbing process, according to which the edge peel problem has been solved, and this technique demonstrated preferable achievements in solving this edge peel problem. In this technique, however, there was need of using a layer comprising colloidal silica as a second sub layer when a strong adhesion was intended to be produced between hydrophobic supports including polyester supports and photographic gelatin compositions, particularly when the so-called dry adhesion before and after development was intended to be strengthened, and no sufficient adhesion was attained in case the second sub layer was a commonly used gelatin layer or in case of so-called monolayer subbing involving no formation of a second sub layer.Further, in the copolymer-containing aqueous compositions, there were used, as adhesion promotors, such compounds as having methylsulfonyloxy or ethyleneimine groups, which compounds were quite effective for improving adhesion but, on the other side, had their drawbacks. One of the drawbacks is that after lapse of a certain period of storage of the copolymercontaining aqueous compositions having incorporated thereinto these compounds, because of high reactivity of said compounds, reaction of said compounds with the copolymer components or reaction between said compounds proceeds and, on that account, there is observed such phenomenon that the polyester supports subjected to subbing treatment using the copolymer-containing aqueous compositions after the lapse of a certain period of storage as aforesaid have little effect of addition thereto of the adhesion promoters, namely, the pot life after addition to the copolymer-containing aqueous compositions of such adhesion promoters as the above-mentioned compounds. Another drawback is that after lapse of a certian period of storage subsequent to the subbing treatment, deterioration in adhesion proceeds with the lapse of time even though at the outset of subbing treatment the effect of the adhesion promotors is obtained and adhesion to a photographic silver halide emulsion layer or gelatin backing layer is found to be favourable. In this case, in particular, the drawback tended to be brought about when a gelatin-containing layer was formed as the second sub layer.This is considered ascribable to the fact that because such adhesion promoters as these compounds are also hardeners for gelatin, unreacted adhesion promotors present in the copolymer sub layer diffuse to migrate into the second gelatin sub layer, whereby said gelatin layer is cross-linked and hardened to an extent more than necessary and, on that account, the hardened second sub layer is insufficiently blended with the photographic silver halide emulsion or gelatin backing to bring about deterioration in adhesion. Further, Japanese Laid-Open-to-Public Publication No. 22735/1978 discloses a subbing process, according to which the defect associated with the subbing treatment with herdeners is alleged to have been solved. In this process, however, there was need of subjecting the surface of copolymer sub layer to modification treatment by means of corona discharge.

Still further, the copolymer-containing aqueous compositions disclosed in Japanese Laid-Open-to Public Publication No. 104913/1977 bring about turbidity in the copolymer sub layer resulted therefrom due to the components of said aqueous composition, and the photographic polyester supports subbed with said aqueous compositions were sometimes found to be inadequate for photographic purposes.

Thus, in the existing circumstances a great desideratum is the advent of polyester supports for photographic purposes which are excellent in characteristics and from which various drawbacks of the prior art have been eliminated.

It is accordingly a primary object of the present invention to provide photographic subbed polyester supports which do not discharge harmful organic solvents, produce favorable adhesion at the time of dry as well as of wet between the support and photographic gelatin composition and are free from edge peel.

A secondary object of the present invention is to provide photographic subbed polyester supports which produce excellent film adhesion even without addition of an adhesion promoter and corona discharge treatment to be applied to the copolymer sub layer thereof.

A third object of the present invention is to provide photographic subbed polyester supports which produce favorable adhesion to the photographic emulsion or the like to be coated thereon even when the supports are stubbed by the so-called monolayer subbing and which are free from edge peel.

A fourth object of the present invention is to provide photographic subbed polyester supports which are free from change in adhesive property with the lapse of a certain period of storage of the copolymer-containing aqueous composition (a subbing liquid).

A fifth object of the present invention is to provide photographic subbed polyester supports, of which the copolymersub layer is excellent in transparency.

A sixth object of the present invention is to provide photographic subbed polyester supports which are free from deterioration in adhesive property with the lapse of a certain period after subbing treatment.

A seventh object of the present invention is to provide photographic subbed polyester supports which are excellent in adhesion even to a backing gelatin layer and free from edge peel.

The above-mentioned objects of the present invention and other objects thereof which will be mentioned later can be accomplished by coating a polyester support on its surface with an aqueous composition as a subbing liquid containing a copolymer consisting essentially of (1) 20-55 wt% nbutyl acrylate monomer, (2) 35-55 wt% glycidyl acrylate and/or glycidyl methacrylate monomer, and (3) 10--30 wt% styrene and/or a-methylstyrene monomer, which will be hereinafter referred to as the first component, the second component and the third component, respectively.

The polyester supports used in the present invention are those which are made of aliphatic diols or aromatic dicarboxylic acids, typical of which is a polyethylene terephthalate support. Preferably usable in the present invention are polyester supports which have been biaxially oriented and thermally fixed.

Further, the polyester supports may be transparent and, if necessary, may contain photographically inertdyes, for example, blue dyes for X-ray film or the like. Before coating the polyester support with the copolymer-containing aqueous composition used as a subbing liquid in the present invention, it is preferable to hydrophilize the surface of said support by means of an appropriate pretreatment, for example, corona discharge treatment, ultra-violet irradiation treatment, flame treatment, etc., thereby attempting improvement in wetting and adhesive properties thereof toward the polyester support.

The copolymer used in the present invention is obtained by aqueous emulsion polymerization of substantial reactive aforesaid three monomers. In this connection, moreover, the copolymer of the present invention may contain, within the-range where no change in properties of the copolymer aimed at in the present invention is brought about, as the fourth (4) component such derivatives starting from acrylic acid or methacrylic acid monomer but are other than the first and the second components, derivatives starting from itaconic acid or maleic anhydride monomer, or vinyl chloride, vinylidene chloride or the like monomers.

The copolymer of the present invention exhibits its adhesion effect by virtue of the combination of the aforesaid three components and thus the present copolymer has preferable properties for photographic purposes.

Concretely speaking, the first component or n-butyl acrylate monomer gives a polymer which is high in viscosity, and in the present copolymer the first component greatly contributes toward adhesive property relative to the polyester support. In this case, however, such contribution is lessened when the content of n-butyl acrylate is smaller than 20 wt%, particularly dry film adhesion force before and after development of light-sensitive photographic material is weakened. On the other hand, when the n-butyl acrylate content is greater than 55 wt%, the formed sub layer becomes considerably soft, whereby blocking is brought about on the support surface during process step before coating a subsequent layer on said sub layer, and thus the resulting subbed polyester support is of little real use.Accordingly, it is essential to use n-butyl acrylate monomer in the range of 20-55 wt%. And the more effective result can be obtained in the range of 30-50 wt%. Further, when n-butyl acrylate monomer is replaced by such a branched monomer as iso-butyl acrylate, sec-butyl acrylate or tert-butyl acrylate, or by such monomer having an alkyl group on the side chain as n-butyl methacrylate, the dry film adhesion of the resulting light-sensitive photographic material becomes insufficient and thus such replacement is not preferable.

Because of the presence of an epoxy group containing in the molecule, the second component or glycidyl acrylate and/or glycidyl methacrylate is effective for allowing the copolymer sub layer to undergo cross-linkage, with the result that the sub layer becomes more favorable in water resisting property with increasing content of the second component. That is, no deterioration in adhesion between the polyester support and copolymer sub layer is brought about even in a wet state as a result of restraining the sub layer from swelling due to the present of water because there is obtained an effect inhibiting permeation of water into the sub layer in a wet state where the light-sensitive photographic material is under development or the like.Thus, the second component exhibits excellent effect on wet film adhesion characteristics including edge peel of the light-sensitive photographic material under development. In this case, however, dry film adhesion of the light-sensitive photographic material before and after development becomes insufficient when the content of glycidyl acrylate and/or glycidyl methacrylate monomer is greater than 55 wt%. On the other hand, if the said content is smaller than 35 wt%, dry film adhesion of the light-sensitive photographic material likewise becomes insufficient.

Accordingly, it is essential to use glycidyl acrylate and/or glycidyl methacrylate monomer in the range of 35-55 wt%. When the range is 40-50 wt%, stronger adhesion is obtainable.

The sub layer become better in its transparency with increasing content of the third component i.e.

styrene and/or cg-methylstyrene from 10 wt% to 30 wt%, with the result that optical characteristics of the subbed support for photographic purposes become excellent, and further the film strength is enhanced to improve scratch characteristics and the second transition temperature of the copolymer rises to improve blocking characteristics. In this case, however, if the styrene and/or a-methylstyrene monomer content is greater than 30 wt%, dry film adhesion of the light-sensitive photographic material before and after development treatment becomes low, or the copolymer sub layer formed on the polyester support assumes an opaque and cloudy state due to poor film forming property thereof, with the result that optical characteristics of the subbed support for photographic purposes are lowered.

Accordingly, it is essential in the copolymer of the present invention to use styrene and/or a- methylstyrene in the range of 10-30 wt%. The range is more preferable of 15-25 wt%. Because an epoxy group reacts to make cross linkage as referred above, molecular weights of the copolymers of the present invention cannot determined exactly. It is, however, presumed that they are above 10,000.

The copolymer to be contained in the copolymer-containing aqueous composition of the present invention is prepared by emulsion polymerization process in the manner as will be mentioned hereinafter and hence the present copolymer is obtained in the form of an aqueous dispersion of particulate emulsion polymerizate, i.e. in the form of the so-called latex. This copolymer of the present invention is prepared, for example, by the following procedure.That is, into a flask equipped with a reflux condenser are added a surface active agent for emulsion polymerization, for example, sodium dodecylbenzenesulfonate, a polymerization initiator, for example, ammonium persulfate, and a polymerization promoter, for example, sodium acid sulfite and, if necessary, is added a molecular weight regulator, and the contents of the flask is maintained at about 800 C. Into the flask are added dropwise with stirring the copolymer component monomers to initiate polymerization, whereupon an aqueous dispersion of the resultant copolymer is obtained. The amount of the surface active agent used in the reaction is less than 5 wt%, preferably 1-2 wt%, based on the amount of the copolymer component monomers.The particle size of the copolymer in the dispersion as obtained is preferably in the vicinity of 0.1 , though the particle size varies depending on the amount of the surface active agent used and on the synthesis conditions such as stirring condition and polymerization temperature employed. The copolymer-containing aqueous composition used in the present invention may also be obtained by dissolving a surface active agent for emulsion polymerization and monomers of the first, second and third components in an appropriate solvent, and the resulting solution is charged with a polymerization initiator in an amount necessary for initiation of the polymerization, heated and then allowed to stand for several hours. Subsequently, the reaction liquid obtained is vigorously mixed with an aqueous solvnet to obtain the desired copolymer-containing aqueous composition.

The copolymer-containing aqueous composition prepared in the manner explained above is obtained in the form of an aqueous dispersion and hence may be used as a subbing liquid, as it is, or, if necessary, organic solvents, surface active agents can be added to the aqueous dispersion to prepare a subbing liquid.

Typical copolymers (exemplified compounds) to be contained in the aqueous copolymer compositions of the present invention and comparative copolymers (they are obtained as aqueous dispersions of particulate emulsion polymerizates because these copolymers are prepared according to emulsion polymerization process in the same manner as in the case of said exemplified compounds) are illustrated below with reference to processes for preparing the same.

PROCESS 1 Preparation of exemplified compounds (1 )-(6) and comparative compounds (1 )-(4) as shown in the following Table 1 Into a 500 ml four necked flask equipped with a stirrer, a reflux condenser, a temperature control type heating equipment, a thermometer and a dropping funnel are placed 200 ml of deaerated distilled water and sodium dodecylbenzenesulfonate as an emulsification dispersant, and the contents of the flask are stirred with heating at a stirring speed of 250 r.p.m. while controlling the temperature inside the flask so as to be maintained at 800C.To the conte'nts of the flask under stirring are added 0.1 5 g of ammonium persulfate as a polymerization initiator and 0.1 5 g of sodium acid sulfite as a polymerization promoter, followed by adding thereto 1/10 of the given amounts of monomers indicated in Table 1, and the addition is interrupted for 10 minutes as soon as polymerization is initiated, and thereafter the remaining monomers are added dropwise at a definite rate over a period of 50 minutes. The temperature inside the flask is controlled by cooling so as to be maintained always at 800 C. during dropwise addition of the monomers where generation of heat is vigorous due to heat of polymerization.

After completion of dropwise addition of the monomers, the reaction is continued for additional 4 hours under the same conditions as before, whereupon the polymerization has practically terminated. The copolymer prepared in this manner are obtained in every case as aqueous dispersion of particulate emulsion polymerizates, of which the solids concentration ranges from 32 to 33% by weight, the surface tension at 250C. ranges from 45 to 52 dyne/cm, the rate of polymerization is above 96%, and the particle size as determined by electron microscopic observation is in the vicinity of 0.1,u. The copolymers thus obtained were measured in the epoxy group content, whereupon the value as measured in each case was within the range of 9398% relative to the calculated value obtained from the charged amount of glycidyl acrylate and of glycidyl methacrylate. The aqueous copolymer dispersions obtained in this manner had their respective pH values in the vicinity of 4, and hence each dispersion was adjusted to pH 7 with a small amount of 1N ammonia water, and the dispersions thus treated were used in examples which will be mentioned later.

TABLE 1

Copolymer (aq. dispersion) obtained by Monomer used in Amount of Process 1 prepraring copolymer monomer added (g) n-Butyl acrylate 20 Exemplified Glycidyl methacrylate 50 compound (1) Styrene 30 n-Butyl acrylate 40 " (2) Glycidyl methacrylate 40 Styrene 20 n-Butyl acrylate 30 " (3) Glycidyl methacrylate 40 Styrene 30 n-Butyl acrylate 55 " (4) Glycidyl methacrylate 35 Styrene 10 n-Butyl acrylate 55 " (5) Giycidyl methacrylate 35 α-methylstyrene 10 n-Butyl acrylate 30 " (6) Glycidyl acrylate 40 Styrene 30 n-Butyl acrylate 30 Comparative Glycidyl methacrylate 60 compound (1) Styrene 10 n-Butyl acrylate 50 " (2) Glycidyl methacrylate 20 Styrene 30 n-Butyl acrylate 10 " (3) Glycidyl methacrylate 50 Styrene 40 n-Butyl acrylate 60 " (4) Glycidyl methacrylate 40 PROCESS 2 Preparation of comparative compound (5), i.e. butadiene-styrene-itaconic acid copolymer (aqueous dispersion) To a stirring type autoclave flushed with nitrogen are fed the starting materials as prescribed below, and emulsion polymerization is initiated at the polymerization temperature of 500C. and polymerization pressure of 5 atm (pressure due to butadiene) and continued for 5 hours to obtain an aqueous copolymer dispersion.

Deaerated distilled water 50 ml Sodium dodecylbenzenesulfonate 0.25 g Ammonium persulfate . 0.200 g Butadiene lOg Styrene 15g Itaconic acid 1g In the dispersion thus obtained, the solids concentration was 32 wt%, the rate of polymerization was 95% and the particle size of particulate copolymerwas 0.11 y. The dispersion immediately after preparation thereof had a pH value of 2.1, and the dispersion was adjusted to pH 7 with a small amount of 1 N ammonia water and used in examples which will be mentioned later. The dispersion after adjustment of the pH thereof had a surface tension of 48 dyne/cm.

Copolymer containing aqueous compositions used in the present invention may contain plasticizers such as dibutyl phthalate, dioctyl phthalate, etc., thickners such as polyvinyl alcohol, carboxymethyl ce!lulose sodium salts of vinyl acetate-maleic acid copolymers, gelatin, etc., various antistatic agents, various dyes and pigments, and thereto can be added natural surface active agents and inorganic or organic antiblocking agents such as silicon oxide, titanium oxide, starch, polymethyl methacrylate, polystyrene, etc. The dispersions may be charged, if necessary, with water miscible solvents for promotion of drying such as methanol, ethanol, acetone; etc, which are not swelling agents or solvents for polyester.Further, the copolymer-containing aqueous compositions used in the present invention may contain such adhesion promoters as compounds having ethylenimine groups, triazine compounds or compounds having methylsulfonyloxy groups, though the present copolymer-containing aqueous compositions inherently exhibit favorable adhesion characteristics without aid from such adhesion promoters.

The copolymer-containing aqueous composition of the present invention is coated as a subbing liquid, according to ordinary coating technique such as dip coating, double roll coating, air knife coating, kiss roll coating, gravure roll coating or reverse coating, at a coverage of 10 to 40 g/m2 of support on a polyester support for light-sensitive photographic material, and then dried by heating at 60 to 1 500C.

according to a conventional method relying on hot air or infrared irradiation.

Thè polyester support obtained by coating on the surface with the copolymer-containing aqueous composition of the present invention to form a sub layer in the manner explained above can be further coated thereon with a hydrophilic polymer-containing aqueous composition or an aqueous gelatin composition to form a second sub layer, followed by drying, and if necessary the polyester support having formed thereon the sub layer can be further subjected to post treatment such as heat treatment at 100 to 1 500C. In this connection, the polyester support coated with the copolymer sub layer of the present invention as a first sub layer can be coated thereon directly with a photographic emulsion layer without forming the aforesaid second sub layer on the first sub layer.Furthermore, before forming a second sub layer on a first sub layer formed on a polyester support by coating thereon a copolymercontaining aqueous composition of the present invention, or before coating a photographic emulsion directly on said first sub layer, the surface of said polyester support can be subjected to such modification treatment by means of corona discharge or the like as disclosed in Japanese Laid-Open-to Public Publications Nos. 3972/1974 and 22735/1978, and by virtue of this treatment, adhesive property of the thus treated polyester support relative to the second sub layer of the photographic emulsion layer can be further improved as well as stabilized.

The above-mentioned second sub layer can be incorporated, for the purposes of preventing it from blocking and electro-static charge and of improving other physical properties thereof, with a variety of additives, of example, compounds having ethyleneimine groups, compounds having methylsulfonyloxy groups or such compounds as triacroyl-s-triazine, etc., particulate substances such as titanium oxide, silicon oxide, polymethyl methacrylate, polystyrene, starch, etc. and various kinds of water-soluble or dispersible high molecular substances.

Furthermore, there may also be used additives capable of cross-linking the epoxy group of glycidyl acrylate and/or glycidyl methacrylate which is one of the copolymer components of the first sub layer, for example, amine derivatives such as hexamethoxymethylmelamine, condensates of amines such as melamine or urea with aldehydes, and organic acids of at least bifunctional such as itaconic acid, maleic acid, trimellitic acid, pyromellitic acid, etc., and catalyst such as para-toluenesulfonic acid, ammonium chloride, ammonium nitrate, etc, for the purpose of promoting the cross-linkage.

The present invention is concretely illustrated below with reference to examples, but it should be construed that the scope of the invention is not limited to the aforementioned exemplified compounds used in those examples, and that embodiments of the invention are not limited to the examples as given.

EXAMPLE 1 The surface of a polyethylene terephthalate support biaxially stretched to a thickness of 1 80 y was subjected to modification treatment using a HFSG-2 type corona discharge apparatus manufactured by Lepel Co., at ordinary pressure under discharge conditions calling for a support travelling speed of 1 5 m/min, a 1.5 mm space between electrodes, an electric power of 200 W and electric current of 0.7 A.

On contact with water, the surface of the polyethylene terephthalate support treated under the abovementioned conditions was found to have a contact angle of 450. Subsequently, each of exemplified compounds (1), (2), (3) and (5) was diluted with water so that the solids concentration became 5 weight percent, and the resulting dilution was charged with saponin in the proportion of 0.4 g per 1 kg of said dilution to obtain a copolymer-containing aqueous composition of the present invention.

The thus obtained copolymer-containing aqueous composition was coated as a subbing liquid on the surface of polyethylene terephthalate support subjected to corona discharge treatment as aforesaid at a coverage of 20 g/m2 by means of a double roll coater, followed by drying for 3 minutes with hot air kept at 1 200C. Separately, a subbing liquid was prepared by incorporating 0.3 g of saponin into 1 kg of an aqueous solution of 10 g of gelatin, and the subbing liquid thus prepared was coated by means of a double roll coater at a coverage of 20 g/m2 on the aforesaid sub layer comprising the copolymer to form a second sub layer, followed by drying for 3 minutes with hot air kept at 100 C. Thereafter, the second sub layer was further subjected to heat treatment for 1 minute with hot air kept at 1400 C. The polyethylene terephthalate supports thus subbed were individually coated with a silver halide photographic emulsion for X-ray film containing silver iodobromide to prepare samples (sample No.

1-4).

In the same manner as above, comparative samples (sample No. 5-7) were prepared using comparative compounds (2), (4) and (5), respectively.

The samples and comparative samples as prepared above were subjected to adhesion test according to the following procedures (A) and (B), respectively, to edge peeling test according to the following procedure (C), and to transparency evaluation test of the subbed polyester support according to the following procedure (D) to obtain the results as shown in Table 2.

(A) Dry adhesion test Before development as well as after development followed by drying, to the surface of the silver halide emu-lsion layer of each sample is applied a conventional cross-cut adhesion test method, wherein a sharp blade (e.g. a razor blade) is used to cut said surface to a depth so as to reach to the support, an adhesive tape (e.g. cellophane adhesive tape) is applied to the cut surface, and the tape thus stuck is suddenly peeled of from said surface. In evaluating the test results as obtained, an instance where no emulsion layer peeled off was graded AA, where the peeled area of the emulsion layer was 15% was graded A, where the peeled area was 630 ,6 was graded B, and where the peeled area was 31-1 pO% was graded C.

(B) Wet adhesion test during development During development, to the surface of the silver emulsion layer of each sample in a wet state is applied a conventional cross-cut adhesion test method, wherein a gimlet-like pointed metal rod is used to cut the emulsion surface in the same manner as in the wet adhesion test and then the cut surface is rubbed to observe whether the rubbed surface peels off from the support or not. In evaluating the test results, an instance where no emulsion layer peeled off was graded AA, where the peeled area of the rubbed emulsion layer was 110% was graded A, where the peeled area was 11-30% was graded B, and where the peeled area was over 30% was graded C.

(C) Edge peel test during development During processing with a developing agent and a fixing agent, each sample in a wet state is strongly rubbed with a finger or a soft rubber in the horizontal direction from an edge of the photosensitive layer of the sample toward the inner side thereof to observe whether the edge of said photosensitive layer peels off from the support or not. In evaluating the test result, in instance where the edge peeled off even to a slight extent was graded "bad" and where no edge peeled off at all was graded "good".

(D) Evaluation of transparency of the subbed polyester support Each polyester support on which the copolymer-containing sub layer was formed was subjected to visual observation. In evaluating the observation results, an instance where no turbidity was observed at all was graded "good" and where turbidity was observed even to a slight extent was graded "bad".

In this connection, of the samples as tested, those which were graded B or higher in the tests (A) and (B), respectively, and "good" in the tests (C) and (D), respectively, are deemed satisfactory from a practical point of view.

TABLE 2

Adhesion Sample Compound No. Dry Wet Edge peel Transparency Exemplified compound (1) 1 B AA Good Good (2) 2 A AA Good Good (3) 3 A AA Good Good ,. (5) 4 B AA Good Good Comparati ve compound (2) 5 C AA Good Good .. (4) 6 A AA Good Bad (5) 7 A C Bad Good As is clear from Table 2, it is understood that the polyester supports subjected to subbing treatment by coating thereon the copolymer-containing aqueous compositions of the present invention are all excellent in adhesion to the photographic layer formed thereon, resistance to edge peel and transparency of the copolymer-containing sub layer. In contrast thereto, the polyethylene terephthalate support subjected to subbing treatment by coating thereon the comparative copolymer-containing aquebus compositions have their defect in any of adhesion to the photographic layer formed thereon, resistance to edge peel and transparency of the copolymer-containing sub layer.

EXAMPLE 2 A polyethylene terephthalate support of 100 y in thickness was subjected to hydrophilization treatment in the same manner as in Example 1. Subsequently, exemplified compounds (2), (3), (4) and (6) were individually diluted with water so that the solids concentration became 5 weight percent, and the resulting dilution was charged with saponin in the proporion of 0.4 g per 1 kg of said dilution to obtain a copolymer-containing aqueous composition of the present invention. The composition thus obtained was then divided into two portions, and one of which was incorporated with 1:5 9, based on 1 kg of said composition, of hexamethylenebis-ethyleneiminoureide which is an adhesion promoter, while the other of which was not incorporated with said adhesion promoter.The copolymer-containing aqueous compositions in the above manner were individually coated as subbing liquids on the aforesaid hydrophilized polyethylene terephthalate support in the same manner as in Example 1 but (a) immediately after preparation thereof and (b) after being allowed to stand at 350C. for 12 hours, respectively.Subsequently, a subbing-liquid was prepared by incorporating 0.2 g of saponin into 1 kg of an aqueous solution of 5 g of gelatin, and the subbing liquid thus prepared was coated by means of a double roll coater at a coverage of 20 g/m2 on the aforesaid copolymer-containing sub layer to form a second sub layer, followed by drying for 2 minutes with hot air kept at 100 C. The polyethylene terephthalate support thus subbed were individually coated on the surface with a lith type silver halide photographic emulsion containing silver chlorobromide (i.e. a photographic emulsion to be subjected to development with the so-called lith developer) to prepare samples (sample No. 8-23).

Separately, comparative samples (sample No. 35) were prepared using comparative compounds (2), (4) and (5), respectively, in the same manner as in the case of the samples of the present invention. The present samples and comparative samples thus prepared were as illustrated in Table 3.

TABLE 3

Use of copolymer composition after preparation thereof Adhesion Immediately after Stood for Compound used promoter preparation (A) 12 hours (B) Examplified compound (2) Not added Sample No. -8 Sample No. 9 (2) Added " 10- " 11 " (3) Not Added " 12 .. 13 (3) Added " 14 " 15 (4) Not added " 16 " 17 .. (4) Added ,, 18 .. 19 " (6) Not aded " 20 " 21 " (6) Added " 22 " 23 Comparative Not added " 24 " 25 compound (2) ,, (2) Added , 26 ,. 27 (4) Not added " 28 " 29 (4) Added " 30 " 31 (5) Not added " 32 " 33 (5) Added " 34 " 35 The present samples and comparative samples were then subjected to adhesion test, edge peel test and transparency evaluation, respectively, in the same manner as in example 1 to obtain the results as shown in Table 4.

TALBE 4

Use of copolymer composition after Adhesion preparation thereof Sample Adhesion Edge Transparency Compound used promoter (Notes 1) No. Dry Wet peel of sub layer Exemplified (a) 8 B AA Good Good compound (2) Not added (b) 9 B AA Good Good (a) 10 A AA Good Good " (2) Added (b) 11 B AA Good Good (a) 12 A AA Good Good " (3) Not Added (b) 13 A AA Good Good (a) 14 A AA Good Good " (3) Added (b) 15 A AA Good Good (a) 16 A AA Good Good " (4) Not added (b) 17 A AA Good Good (a) 18 A AA Good Good " (4) Added (b) 19 A AA Good Good (a) 20 B AA Good Good " (6) Not added (b) 21 B AA Good Good (a) 22 A AA Good Good " (6) Added (b) 23 B AA Good Good TABLE 4 (Continued)

Use of copolymer composition after Adhesion preparation thereof Sample Adhesion Edge Transparency Compound used promoter (Notes 1) No. Dry Wet peei of sub layer Comparativs (a) 24 C AA Good Good compound (2) Not added (b) 25 C AA Good Good (a) 26 A AA Good Good " (2) Added (b) 27 C AA Good Good (a) 28 A AA Good Bad " (4) Not added (b) 29 A AA Good Bad (a) 30 A AA Good Bad " (4) Added (b) 31 A AA Good Bad (a) 32 A C Bad Good " (5) Not added (b) 33 A C Bad Good (a) 34 A A Bad Good " (5) Added (b) 35 A C Bad Good Notes 1(a) ... Coated immdiately after preparation. (b) ... Coated after standing for 12 hrs.

As is clear from Table 4, it is understood that the polyethylene terephthalate supports subjected to subbing treatment by coating thereon with the copolymer-containing aqueous compositions of the present invention are all excellent, even without addition to the compositions of an adhesion promoter, in adhesion to the photographic layer formed thereon without causing edge peel and in transparency of the copolymer sub layer from a practical point of view.On the other hand, the comparative samples containing the comparative compounds (2) and (5), respectively, deteriorate in adhesion when the copolymer compositions are used after being allowed to stand for a given period of time, though adhesion is improved by virtue of addition thereto of the adhesion promoter, and these samples are deemed inadequate from a practical point of view,.and the samples containing the comparative compound (5) are suffering from edge peel. Further, the comparative samples containing the comparative compound (4) are deemed inadequate since trubidity is observed in the copolymer sub layer.

EXAMPLE 3 A polyethylene terephthalate support of 1 00 y in thickness was subjected to hydrophilization treatment in the same manner as in Example 1. Separately, exemplified compounds (2) and (3) were individually diluted with water so that the solids concentration became 5 weight percent, and the resulting dilution was charged with saponin in the proportion of 0.4 g per 1 kg of said dilution to obtain a copolymer-containing aqueous composition of the present invention. The composition thus obtained was then divided into two portions, and one of which was incorporated in the same manner as in Example 2 with 1.5 g, based on 1 kg of the copolymer-containing aqueous composition, of hexamethylenebisethyleneiminoureide which is an adhesion promoter.The copolymer-containing aqueous compositions prepared in this manner were individually coated as subbing liquids on the surface of the aforesaid hydrophilized polyethylene terephthalate support according to the procedure described in Example 1 and then dried. Subsequently, a subbing liquid was prepared by incorporation 0.2 g of saponin into 1 kg of an aqueous solution of 5 g of gelatin, and the subbing liquid thus prepared was coated by means of a double roll coater at a coverage of 20 g/m2 on the aforesaid copolymercontaining sub layer to form a second sub layer, followed by drying for 2 minutes with hot air kept at 1000C. In order to investigate deterioration with the lapse of time in adhesion of the polethylene terephthalate supports thus subbed, these supports were allowed to stand for two weeks in the surrounding atmosphere at 500 C. and 80% RH.The subbed polyethylene terephthalate supports thus treated were individually coated on the surface with a lith type silver halide photographic emulsion containing silver chlorobromide to prepare samples of the present invention (sample No. 36-43).

Separately, comparative samples (sample No. 44-51) were prepared using comparative compounds (3) and (5), respectively, in the same manner as in the case of the present samples. The present samples and comparative samples as prepared were as illustrated in Table 5.

TABLE 5

Use of support after subbing treatment Immediately Stood for after 2 weeks Adhesion treatment at 50 C and Compound used promoter (a) 80% RH (b) Exemplified compound (2) Not added Sample No. 36 Sample No. 37 " (2) Added ,, 38 X 39 ,, (3) Not added " 40 ,. 41 " (3) Added ,, 42 ,, 43 Comparative compound (3) Not added ,, 44 " 45 " (3) Added 46 " 1 47 ,, (5) Not added " 48 ,, 49 ,, (5) Added .. 50 " 51 The present samples and comparative samples were then subjected to adhesion test and edge peel test, respectively, in the same manner as in Example 1 to obtain the results as shown in Table 6.

TABLE 6

Storage under given Adhesion Adhesion conditions Sample Edge Compound used promoter (Notes 2) No. Dry Wet peel Exemplified compound (2) Not added (a) 36 A AA Good " (2) Not added (b) 37 A AA Good (2) Added (a) 38 A AA Good " (2) Added (b) 39 A B Good Not Not added (a) 40 A AA Good ,, (3) Not added (b) 41 A AA Good . (3) (3) Added (a) 42 A AA Good . . (3) Added (b) 43 A B Good Comparative compound (3) Not added (a) 44 C AA Good (3) Not added (b) 45 C AA Good (3) Added (a) 46 B AA Good (3) Added (b) 47 C B Good " (5) Not added (a) 48 A C Bad (5) Not added (b) 49 A C Bad (5) Added (a) 50- A A Bad (5) Added (b) 51 A C Bad Notes 2 (a) . . . Subbed polyethylene terephthalate support was used immediately after subbing treatment.

(b).. , After subbing treatment, the polyethylene terephthalate support was allowed to stand for two weeks in the surrounding atmosphere at 500C. and 80% RH.

As is clear from Table 6, it is understood that the polyethylene terephthalate supports subjected to subbing treatment by coating thereon the copolymer-containing aqueous compositions of the present invention are all excellent, irrespective of addition of the adhesion promotor, in adhesion to the photographic layer and rather found to be less in charge of adhesion with the lapse of time when no adhesion promoter is incorporated into the copolymer-containing aqueous compositions. It is also understood, on the other hand, that the comparative samples containing the comparative compound (3) are poor in wet adhesion to the photographic layer, and the comparative samples containing the comparative compound (5) are poor both in wet adhesion and edge peel.

EXAMPLE 4 A polyethylene terephthalate support of 100 u in thickness was subjected to hydrophilization treatment in the same manner as in Example 1. Separately, exemplified compounds (2), (3) and (6) were individually diluted with water so that the solids concentration became 5 weight percent, and the resulting dilution was charged with saponin in the proportion of 0.49 per 1 kg of said dilution to prepare.

a copolymer-contianing aqueous composition. The copolymer-containing aqueous compositions prepared in this manner were individually coated as subbing liquids in the same manner as in Example 1 on the surface of the aforesaid polyethylene terephthalate support subjected to hydrophilization treatment and then dried. Subsequently, the surface of the polyethylene terephthalate support provided with the aforesaid copolymer sub layer was subjected to modification treatment under ordinary pressure by means of HFSG-2 type corona discharge apparatus manufactured by Lepel Co., under discharge conditions calling for a support traveling speed of 10 'meter/min,1.5 mm space between electrodes, electric power of 200 W and electric current of 0.7 A.Separately, a subbing liquid was prepared by incorporating 0.3 g of saponin into 1 kg of an aqueous solution of 10 g of gelatin, and the subbing liquid thus prepared was coated at a coverage of 20 g/m2 by means of a double roll coater on the copolymer sub layer subjected previously to corona discharge treatment to form a second sub layer, followed by drying for 1 minute with hot air kept at 100 C. The support thus provided with the second sub layer was further subjected to heat treatment for 1 minute with hot air kept at 1 400 C. The sebbed polyethylene terephthalate supports thus obtained were individually coated on the surface with a backing gelatin composition for gravure film to prepare samples (sample No. 52-54) of the present invention.Separately, comparative samples (sample No. 55-57) were prepared using comparative compounds (1), (4) and (5), respectively in the same manner as in the case of the present samples.

The present samples and comparative samples thus prepared were subjected to film adhesion test, edge peel test and transparency evaluation, respectively, in the same manner as in Example 1 to obtain the results as shown in Table 7.

TABLE 7

Adhesion Sample Edge Trans Compound used No. . Dry Wet peel parency Exemplified compound (2) 52 A AA Good Good " (3) 53 A AA Good Good " (6) 54 A AA Good Good Comparative compound (1) 55 C AA Good Good ,, (4) 56 A AA Good Bad ,, (5) 57 A C Bad Good As is clear from Table 7, it is understood that as compared with the polyethylene terephthalate supports coated with the comparative copolymer-containing aqueous compositions as subbing liquids, the polyethylene terephthalate supports coated with the present copolymer-containing aqueous composition as subbing liquids are all excellent in adhesion to the backing gelatin layer, resistance to edge peel of the backing gelatin layer, and transparency of the copolymer sub layer.

EXAMPLE 5 A biaxially stretched polyethylene terephthalate support of 180,u in thickness was subjected to hydrophilization treatment according to the procedure described in Example 1. Subsequently, exemplified compounds (2) and (3) were individually diluted with water in the same manner as in Example 1, and the resulting dilution was charged with 0.2 g based on 1 kg of said dilution of alkylarylpolyether sulfate type surface active agent represented by the following structural formula to prepare a copolymer-containing aqueous composition of the present invention.

The copolymer-containing compositions prepared in this manner were individually coated as subbing liquids according to Example 1 on the surface of the polyethylene terephthalate support subjected previously to hydrophilization treatment and then dried. Subsequently, the surface of the polyethylene terephthalate support provided with a copolymer sub layer in the above manner was subjected in the same way as in Example 3 to modification treatment under ordinary pressure by means of HFSG-2 type corona discharge apparatus manufactured by Lepel Co. under discharge conditions calling for a support traveling speed of 10 m/min, space of 1.5 mm between electrodes, electric powe: of 200 W, and electric current of 0.7 . On each of the modification treated copolymer sub layers thus obtained was coated a silver halide photographic emulsion for X-ray film to prepare samples (sample No. 58-59) of the present invention. Separately, comparative sampes (sample No. 60-62) were prepared using comparative compounds (1), (2) and (5) in the same manner as in the case of the present samples.

The present samples and comparative samples thus prepared were subjected in the same manner as in Example 1 to adhesion test, edge peel test and transparency evaluation of the copolymer sub layer to obtain the results as shown in Table 8.

TABLE 8

Adhesion Resistance Sample to edge Trans Compound used No. Dry Wet peel parency Exemplified compound (2) 58 A A Good Good . . (3) 59 A A Good Good Comparative compound (1) 60 C A Good Good (4) 61 C A Good Bad (5) 62 | B D Qad Good As is clear from Table 8, it is understood that the copolymer sub layer, even when coated as a monolayer on the polyethylene terephthalate support without being provided with a second sub layer, is excellent in adhesion to the photographic layer, resistance to edge peel as well as in transparency of the copolymer sub layer.

EXAMPLE 6 The surface of a biaxially stretched polyethylene terephthalate support of 100 y in thickness was subjected irradation for 1 5 minutes at a distance of 2 cm from a light source to the support surface using a 400 W low pressured mercury lamp with the principal wavelength of 2537 A under the irradiation atmosphere at 250C. and 55% RH. The surface of the polyethylene terephthalate support treated under the above conditions was in contact with water at an angle of 55 .

Subsequently, exemplified compounds (1), (2), (3) and (4) were individually diluted with water so that the solids concentration became 10 weight percent. The copolymer-containing aqueous compositions prepared in this manner were individually coated as subbing liquids at a coverage of 1 5 g/m2 by means of an air knife coater on the surface of the polyethylene terephthalate support subjected previously to hydrophilization treatment and then dried for 3 minutes with hot air kept at 1200 C. to from a first sub layer on said surface.Further, a subbing liquid prepared by incorporating 0.3 g of saponin into 1 kg of an aqueous solution of 10 g of gelatin was coated at a coverage of 20 g/m2 by means of an air knife coater on the first sub layer, followed by drying for 2 minutes with hot air kept at 100 C. On the surface of the thus subbed polyethylene terephthalate support which had been further subjected to heat treatment for T minute with hot air kept at 1 400C. was coated a lith type silver halide photographic emulsion containing silver chlorobromide to prepare samples of the present invention (sample No. 63-66). Separately, comparative samples (sample No. 67-69) were prepared using comparative compounds (3), (4) and (5), respectively, in the same manner as in the case of the present samples. Furthermore, a comparative sample (sample No. 70) was prepared in the same manner as in the case of the present samples using comparative compound (6) which is a copolymer compound consisting of the following components disclosed in Japanese Laid-Open-to-Public Publication No.22735/1978.

[Composition of comparative compound (6)] Ethyl acrylate 36 mol% Methyl methacrylate 29 mol % Glycidyl methacrylate 8 mol % Hydroxyethyl methacrylate 2 mol % Acrylonitrile 25 mol % The present samples and comparative samples thus prepared were subjected in the same manner as in Example 1 to film adhesion test, edge peel test and transparency evaluation of the copolymer sub layer to obtain the results as shown in Table 9.

TABLE 9

Film adhesion Resistance Sample to edge Trans Compound used No. Dry Wet peel parency Exemplified compound (1) 63 B AA Good Good " (2) 64 A AA Good Good " (3) 65 A AA Good Good " (4) 66 B AA Good Good Comparative compound (3) 67 C AA Good Good ,, (4) 68 A AA Good Bad " (5) 69 A C Bad Good (6) 70 C C Bad Good As is clear from Table 9, it is understood that in comparison with the polyethylene terephthalate supports respectively coated with the comparative copolymer-containing aqueous compositions, the polyethylene terephtha late supports respectively coated with the present copolymer-containing aqueous compositions are excellent in every respect, i.e. film adhesion, resistance to edge peel and transparency of the copolymer sub layer.

Claims (8)

1. A subbing liquid for a photogrpahic polyester support which comprises an aqueous composition.

containing a copolymer of (1) 20 to 55 wt.% of n-butyl acrylate monomer; (2) 35 to 55 wt.% of glycidyl acrylate and/or glycidyl methacrylate monomer, and (3) O to 30 wt.% of styrene and/or a-methyl styrene monomer.

2. A subbing liquid as claimed in Claim 1 wherein the copolymer comprises (1) 30 to 50 wt.% of n-butylacrylate monomer (2) 35 to 55 wt.% of glycidyl acrylate and/or glycidyl methacrylate monomer, and (3) 10 to 30 wt.% of styrene and/or a-methyl styrene monomer.

3. A subbing liquid as claimed in Claim 1 or 2 wherein the copolymer comprises (1) 30 to 50 wt.

% of n-butyl acrylate monomer, (2) 40 to 50 wt.% of glycidyl acrylate and/or glycidyl methacrylate monomer and (3) 10 to 30 wt.% of styrene and/or cu-methyl styrene monomer.

4. A subbing liquid as claimed in any preceding Claim wherein the copolymer comprises (1) 30 to 50 wt.% of n-butyl acrylate monomer, (2) 40 to 50 wt.% of glycidyl acrylate and/or glycidyl methacrylate monomer, and (3) 5 to 25 wt.% of styrene and/or a-methyl styrene monomer.

5. A subbing liquid as claimed in ány preceding Claim which contains a surface active agent.

6. A subbing liquid as claimed in Claim 1 and substantially as hereinbefore described with reference to any of Exemplified Compounds 1 to 6 and Examples 1 to 6.

7. A photographic polyester support having a sub layer derived from a subbing liquid as claimed in any of the preceding Claims.

8. A photographic support as claimed in Claim 1 and substantially as hereinbefore described with reference to any of Examples 1 to 6.