US3607286A

US3607286A - Photographic material comprising an antistatic coating

Info

Publication number: US3607286A
Application number: US838350A
Authority: US
Inventors: Henry Walter Wood
Original assignee: Ilford Ltd
Current assignee: Ilford Imaging UK Ltd
Priority date: 1968-07-03
Filing date: 1969-07-01
Publication date: 1971-09-21
Anticipated expiration: 1988-09-21
Also published as: DE1933843A1; GB1266683A; FR2012240A1; BE735432A

Abstract

This application describes photographic material which comprises a support base having coated thereon on one or both sides at least one photographic emulsion layer, and having coated on each topmost emulsion layer a gelatin supercoat layer, there being present on at least one supercoat layer an antistatic layer which is a layer of a homopolymer of a compound of general formula I: (CH2 CH - CH2)2NR1R2 X I where R1 and R2 are each hydrogen atoms or alkyl groups and X is an anion, or a copolymer thereof with minor amounts of other ethylenically unsaturated monomers, the said homo- or copolymer layer having been coated from a lower primary alcohol solution, or photographic material which comprises a support base which has on one side thereof at least one photographic emulsion layer and which has on the other side an antistatic layer which is a layer of a homopolymer of a compound of the above formula I or a copolymer thereof with minor amounts of other ethylenically unsaturated monomers.

Description

United States Patent [72] Inventor Henry Walter Wood llford, England [21] Appl. No. 838,350 [22] Filed July 1, 1969 [45] Patented Sept. 21, 1971 [73] Assignee Ilford Limited llford, England [32] Priority July 3, 1968 [33] Great Britain l 31,705/68 [54] PHOTOGRAPHIC MATERIAL COMPRISING AN ANTISTATIC COATING 8 Claims, No Drawings [52] [1.8. Ci 96/87 A [51] lnt. Cl G03c 1/82 [50] Field of Search 96/87 A,

[56] References ited UNITED STATES PATENTS 3,399,995 9/1968 Winchell 96/87 Primary Examiner-Ronald H. Smith AttorneyCushman, Darby & Cushman ABSTRACT: This application describes photographic material which comprises a support base having coated thereon on one or both sides at least one photographic emulsion layer, and having coated on each topmost emulsion layer a gelatin supercoat layer, there being present. on at least one supercoat layer an antistatic layer which is a layer of a homopolymer ofa compound of general formula I:

where R and R are each hydrogen atoms or alkyl groups and X.is an anion, or a copolymer thereof with minor amounts of other ethylenically unsaturated monomers, the said homoor copolymer layer having been coated from a lower primary alcohol solution, or photographic material which comprises a support base which has on one side thereof at least one photographic emulsion layer and which has on the other side an antistatic layer which is a layer of a homopolymer of a compound of the above formula I or a copolymer thereof with minor amounts of other ethylenically unsaturated monomers.

PHOTOGRAPHIC MATERIAL COMPRISING AN ANTllSTATIC COATING This invention relates to photographic film material provided with an antistatic layer and to the production of such film material.

It is known that photographic film material exhibits a tendency to pick up electrostatic charges during the course of its manufacture and also when it is being processed. When an electrostatically charged film is discharged so called static marks are produced. These marks show as areas of local overexposure on the developed film. It is possible to reduce the tendency of photographic film to pick up electrostatic charges by the provision of a layer which has a relatively high electroconductivity. Any electrostatic charge picked up by a film having such a layer rapidly leaks to earth without causing a discharge.

It is the object of the present invention to provide photographic material which comprises such a layer of relatively high conductivity.

According to the present invention, therefore, there is provided photographic material which comprises a support base having coated thereon on one or both sides at least one photo graphic emulsion layer, and having coated on each topmost emulsion layer a gelatin supercoat layer, there being present on at least one supercoat layer a layer of a homopolymer of a compound of general formula I:

where R and R are each hydrogen atoms or alkyl groups and X is an anion, or a copolymer thereof with minor amounts of other ethylenically unsaturated monomers, the said homeor copolymer layer having been coated from a lower primary alcohol solution, or photographic material which comprises a support base which has on one side thereof at least one photographic emulsion layer and which has on the other side a layer of a homopolymer of a compound of the above formula I or a copolymer thereof with minor amounts of other ethylenically unsaturated monomers.

By minor amounts of other ethylenically unsaturated monomers is meant at most 7 percent of other monomers.

By lower primary alcohol is meant a primary alcohol which comprises up to six carbon atoms, e.g. methanol, ethanol, butanol and methyl cellosolve. The preferred primary alcohol is methanol.

There was described in our copending application Ser. No. 832,021 filed June It), 1969, photographic emulsions which comprise homopolymers of compounds of formula I and copolymers thereof. The effect of adding these compounds to photographic emulsions was shown to be an increase in photographic speed of the emulsion. Thus when homopolymers of compounds of the above formula I and copolymers thereof are included in photographic material as a conductive layer it is important that they do not diffuse into the photographic emulsion layer.

It was found that when there was a gelatin supercoat over the emulsion layer or layers and the polymeric compounds were coated from a primary alcohol solution, that the alcohol did not swell the gelatin supercoat layer but evaporated rapidly leaving a layer of the polymeric substance which did not diffuse into the underlying emulsion layer. When homopolymers of compounds of formula I or copolymers thereof were coated onto the supercoat layer in aqueous solution, because the water swelled the supercoat layer, a proportion of the polymeric substance diffused into the photographic emulsion layer end affected its photographic properties.

However when the homopolymers of formula I or copolymers thereof are coated onto the back of the photographic material, i.e., the side of photographic material which has no emulsion coated thereon, they may be coated from aqueous solution or from a lower primary alcohol solution. In this case the impermeable base protects the photographic emulsion from the coating solution.

The invention is of particular use in regard to X-ray films which are coated on each side with a photographic emulsion layer and with a supercoat layer. In the case of such film material it is preferred that each supercoat layer has coated thereon a layer ofa homopolymer ofa compound of formula I or a copolymer thereof, the said layer having been coated from a lower primary alcohol solution.

It is to be understood, however that the invention also covers photographic material which comprises a base support having on one side at least one photographic emulsion layer, and having coated on the top most emulsion layer a gelatin supercoat layer, there being present on the supercoat layer a layer of a homopolymer of a compound of formula I or a copolymer thereof, this said layer having been coated from a lower primary alcohol solution and on the other side a layer of a homopolymer of a compound of formula I or a copolymer thereof.

It is thought that the homopolymers of use in the present invention have the general formula II:

where R,, R and X have the meanings assigned to them above and n is an integral number.

Homopolymers of the above type have been described by Butler and Angelo. J. Amer. Chem. Soc. 1957, 79, 3,128.

Copolymers which comprise units of the above formula II have been described by Schuller et al. Journal of Chemical Engineering Date. 1959, 4, 1,273. The copolymers may be of different types, for example the copolymer may be a copolymer which comprises a chain of units of general formula II, there being dispersed in the chain units derived from other ethylenically unsaturated monomers such as vinyl pyrrolidone. Alternatively the copolymer may be a cross-linked copolymer which comprises cross-linked chains of units of general formula II there being dispersed in the chain units derived from compounds of general formula I but wherein at least one of R or R is an allyl group. The presence of these allyl groups causes cross-linking between the chains. In another type of copolymer the homopolymer chains or the copolymer chains, i.e., chains which comprise dispersed therein units derived from other monomers such as vinyl pyrrolidone, may be cross-linked by compounds having two double bonds such as methylenebisacrylamide.

The effect of cross-linking the homopolymer or the random copolymer is to increase the effective molecular weight of the polymeric material and to decrease its solubility in alcohol. Thus only a small amount of cross-linking can take place before the homopolymer or copolymer becomes insoluble. On the other hand in some instances it is desirable that some cross-linking has taken place since this renders the polymeric material less likely to diffuse.

In the preferred compounds of formula I for use in the invention R and R are each alkyl groups and most preferably are ethyl or methyl groups.

The following examples will serve to illustrate the invention.

EXAMPLE I Pieces of an X-ray film bearing on each side of the support, in order, a photographic silver halide emulsion layer and a gelatin supercoat layer were further coated in the dry state (on both sides) with methanolic solutions of polymers A and B respectively.

Polymer A: a copolymer of the compound of general formula I as given above wherein R =R ethyl and X bromide, with 1 percent acrylamide.

Polymer B: a copolymer of the compound of general formula I as given above wherein R,=R methyl and X chloride,

The results of the two tests are shown in table I below.

TABLE I Polymer Methanol Test l Test 2 soln. log R v./cm.

It can be seen that the polymers have given an improved result, as judged by either test. Polymer B is more active than A and this is a general feature of compounds having methyl groups on the nitrogen atoms.

Coating from a I percent methanolic solution of polymer gave a coating weight of approximately 5 mg./dm. and other strengths pro rata.

EXAMPLE II.

Pieces of .an X-ray film bearing on each side of the support, in order, a photographic silver halide emulsion layer and a gelatin supercoat layer were further coated in the dry state on each side with a methanolic solution of the following polymers:

A: a copolymer of the compound of general formula I wherein R,=R, ethyl and X bromide, with 1 percent acrylamide (polymer A of Example I).

C: a copolymer of the compound of general formula I wherein R,=R methyl and X chloride, with 1 percent acrylamide.

D: a copolymer of the compound of general formula I wherein R, and R are methyl and X is chlorine with 5 percent vinylpyrrolidone.

The following two tests were applied to the dried pieces of X-ray film at percent R.H.

l. The resistivity of the assembly was measured under an applied potential of IOkV; the result being expressed as log R q).

2. The pieces of film were passed through a pair of rubber rollers to create a charge which was measured by an adjacent field meter; the result being expressed as V./cm. The peak field strength is shown in table 2 which follows together with the value after a decay time of 20 seconds.

It can be seen that the performance of the polymers is main tained at the lower humidity prevailing in the example. Again the compounds with methyl roups on the nitrogen are more effective. After a short time $20 inches), no static can be detected on the films with coatings of polymers C and D.

The adjacent field meter used in the above experiment is described in our Belgian Pat. No. 726,369.

I claim as my invention:

1. Photographic material which comprises a film support having coated thereon on one or both sides at least one photographic emulsion layer, and having coated on each top-most emulsion layer a gelatin supercoat layer, there being present on at least one supercoat layer as an antistatic layer a layer of a homopolymer of a compound of the general formula:

where R, and R are each hydrogen atoms or alkyl groups and X is an anion, or a copolymer thereof with up to 7 percent of other ethylenically unsaturated monomers, the said homoor copolymer layer having been coated from a lower primary alcohol solution.

2. Photographic material according to claim 1 wherein in the compound therein defined R, and R are each methyl groups.

3. Photographic material according to claim I wherein the copolymer layer is a copolymer of the compound defined in claim 1 together with up to 7 percent of vinylpyrrolidone. acrylamide or styrene.

4. Photographic material which comprises a film support which has on one side thereof at least one photographic emulsion layer and which has on the other side an antistatic layer which is a layer of a homopolymer of a compound of the general formula where R, and R are each hydrogen atoms or alkyl groups and X is an anion, or a copolymer thereof with up to 7 percent of other ethylenically unsaturated monomers.

5. Photographic material according to claim 4 wherein in the compound therein defined R, and R are each methyl groups.

6. Photographic material according to claim 4 wherein the copolymer layer is a copolymer of the compound defined in claim 4 together with up to 7 percent of vinylpyrrolidone, acrylamide or styrene.

7. X-ray film material which comprises a film support having coated on each side a photographic emulsion layer and having coated on each emulsion layer a gelatin supercoat layer, there being present on each supercoat layer an antistatic layer which is a layer ofa homopolymer of a compound of the general formula:

where R, and R are each hydrogen atoms or alkyl groups and X is an anion, or a copolymer thereof with up to of other ethylenically unsaturated monomers, the said homoor copolymer layer having been coated from a lower primary alcohol solution.

8. A process for the preparation of an antistatic layer on photographic material which comprises a film support having coated thereon on one or both sides at least one photographic emulsion layer, and having coated on each top-most emulsion layer a supercoat layer, which process comprises coating on at least one supercoat layer a lower primary alcohol solution of a homopolymer of a compound of the general formula:

where R, and R are each hydrogen atoms or alkyl groups and X is an anion, or a copolymer thereof with up to 7 percent of other ethylenically unsaturated monomers and removing the lower primary alcohol.

Claims

2. Photographic material according to claim 1 wherein in the compound therein defined R1 and R2 are each methyl groups.
3. Photographic material according to claim 1 wherein the copolymer layer is a copolymer of the compound defined in claim 1 together with up to 7 percent of vinylpyrrolidone, acrylamide or styrene.
4. Photographic material which comprises a film support which has on one side thereof at least one photographic emulsion layer and which has on the other side an antistatic layer which is a layer of a homopolymer of a compound of the general formula (CH2 CH-CH2)2NR1R2 X where R1 and R2 are each hydrogen atoms or alkyl groups and X is an anion, or a copolymer thereof with up to 7 percent of other ethylenically unsaturated monomers.
5. Photographic material according to claim 4 wherein in the compound therein defined R1 and R2 are each methyl groups.
6. Photographic material according to claim 4 wherein the copolymer layer is a copolymer of the compound defined in claim 4 together with up to 7 percent of vinylpyrrolidone, acrylamide or styrene.
7. X-ray film material which comprises a film support having coated on each side a photographic emulsion layer and having coated on each emulsion layer a gelatin supercoat layer, there being present on each supercoat layer an antistatic layer which is a layer of a homopolymer of a compound of the general formula: (CH2 CH-CH2)2NR1R2 X where R1 and R2 are each hydrogen atoms or alkyl groups and X is an anion, or a copolymer thereof with up to of other ethylenically unsaturated monomers, the said homo- or copolymer layer having been coated from a lower primary alcohol solution.
8. A process for the preparation of an antistatic layer on photographic material which comprises a film support having coated thereon on one or both sides at least one photographic emulsion layer, and having coated on each top-most emulsion layer a supercoat layer, which process comprises coating on at least one supercoat layer a lower primary alcohol solution of a homopolymer of a compound of the general formula: (CH2 CH-CH2)2NR1R2 X where R1 and R2 are each hydrogen atoms or alkyl groups and X is an anion, or a copolymer thereof with up to 7 percent of other ethylenically unsaturated monomers and removing the lower primary alcohol.