US3700635A - Polymers of n-(tris(hydroxymethyl)methyl)acrylamide - Google Patents

Abstract

PHOTOGRAPHIC SILVER HALIDE COMPOSITIONS AND ELEMENTS HAVING IMPROVED COVERING POWER AND SENSITOMERTRIC PROPERTIES, OBTAINED BY EMPLOYING POLYMERIC ADDITIVES IN A PHOTOGRAPHIC BINDER ARE DISCLOSED. SAID POLYMERS COMPRISE RECURRING N-(TRIS(HYDROXYMETHYL)METHYL) ACRYLAMIDE UNITS. PROCESSES FOR EFFECTING SAID IMPROVED PROPERTIES AND NOVEL POLYMERS ARE ALSO DISCLOSED.

Description

United States Patent once 3 ,700,635 Patented Oct. 24, 1972 3,700,635 POLYMERS F N-[TRIS(HYDROXYMETHYL) METHYL1ACRYLAMIDE David Philip Brust, Louis Morton Minsk, and Edward Peter Abel, Rochester, N.Y., assignors to Eastman Kodak Company, Rochester, N.Y.

No Drawing. Original application Apr. 2, 1969, Ser. No. 812,882. Divided and this application Feb. 16, 1971, Ser. No. 115,723

Int. Cl. C08f 15/02 US. Cl. 260-803 N 3 Claims ABSTRACT OF THE DISCLOSURE lhotographic silver halide compositions and elements having improved covering power and sensitometric properties, obtained by employing polymeric additives in a photographic binder are disclosed. Said polymers comprise recurring N-[tris(hydroxymethyl)methyl] acrylamide units. Processes for elfecting said improved properties and novel polymers are also disclosed.

This application is a division of our copending application Ser. No. 812,882 filed Apr. 2, 1969 and now US. Pat. No. 3,591,387.

BACKGROUND OF THE INVENTION Field of the invention This invention relates to useful photographic processes, to novel photographic silver halide compositions, to novel polymers used in said compositions and to elements comprising said compositions. In one aspect, this invention relates to light-sensitive compositions comprising a polymer which imparts improved characteristics to photographic silver halide emulsions. In another aspect, this invention relates to processes for achieving said characteristics. In still another aspect, this invention relates to photographic elements comprising a hydrophilic colloid in combination with a water-soluble linear addition polymer. In yet another aspect this invention relates to photographic elements comprising a hydrophilic colloid in combination with a polymer latex, a water-soluble linear addition polymer and dicarboxylic acid esters.

Description of the prior art It is well known that by the addition of certain additives to light-sensitive compositions such as emulsions containing silver halide, for example, improved sensitometric characteristics can be attained. In particular, the characteristics of increased covering power and stable wet and dry density values are of special interest to those engaged in the photographic arts and more specifically those concerned with the manufacture of light-sensitive emulsions. The term covering power is generally understood to mean the ratio of the optical density of developed silver to the actual quantity of silver present in the photographic composition. The maximum optical density after exposure, processing and drying depends only in part upon the amount of free silver which results from the development process. It also depends upon the manner in which the silver is laid down in the photographic element during processing and the stresses to which it is subjected during drying.

Photographic silver halide emulsions possessing increased covering power are of considerable interest and are particularly desirable since their use results in an increase in gamma and very often an increase in speed while the silver content is maintained at the same level. While covering power, and therefore silver density, can be thus increased, it is also essential that variations between wet and dry states of the photographic compositions be minimized. For example, it is often the practice for purposes of expedience in the graphic arts to measure contrast and density of wet processed film. If unpredictable and substantial density changes occur in the film upon drying, the photographic technician cannot rely upon his initial measurements in order to control contrast and density of the photographic negatives and positives made therefrom.

Further, a loss in density on drying represents a loss of covering power, i.e., a less efi'icient utilization of the amount of silver present to achieve practical density.

In previous attempts to reduce or eliminate changes in covering power and to stabilize density loss in photographic silver halide emulsions containing a hydrophilic colloid such as gelatin, various polymeric addenda have been described as useful therefor. However, when these polymeric addenda, for example, such as polyacrylamide, poly[N- (Z-hydroxyethyl)acrylamide], poly(vinyl pyrrolidone), poly (N-acrylylmorpholine) and the like, are added jointly with other additives such as polymeric latexes, the beneficial effect of the covering power addenda is most often lost or appreciably diminished. By polymeric latex, it will be understood that we mean a colloidal dispersion of a insoluble polymer in an essentially aqueous system.

Furthermore, while certain polymers such as polyacrylamide are indeed known to increase covering power and inhibit density loss on drying of photographic compositions, their elfectiveness seems to be limited either to those compositions which are all gelatin or to those which are combinations of gelatin and synthetic polymer. A few, unpredictably, such as poly(vinyl pyrrolidone) and certain polyvinyl esters of dicarboxylic acids such as succinoylated poly(vinyl alcohol) function in both all-gelatin and gelatin-synthetic polymer combinations but no polymer composition has been described heretofore which achieves the above effects in both all-colloid systems such as gelatin and colloid-polymer combinations without causing a softening of the emulsion coating.

The art would be greatly enhanced by photographic compositions which could effectively, economically and conveniently utilize the advantages of flexibility, lackof dimensional change and the like possessed by polymeric latex-containing systems. Most advantageously, the art would be further benefited from substances which produce stability in density on drying in both colloid systems, such as gelatin, and colloid polymeric soluble or Water insoluble-latex combinations without seriously impairing the hardness of the coated emulsions.

SUMMARY OF THE INVENTION:

This invention relates to improving the characteristics of compositions comprising a photographic silver halide and a binder by incorporating in said binder, and in elements comprising said compositions, a N-[tris(hydroxymethyl)methyl] substituted acrylamide polymer having recurring units of the formula R {CHI-} =0 1 m HOCHr--CH OH where R is hydrogen, methyl or ethyl. The N-substituted acrylamide polymer can be used in any effective concentration, a suitable concentration often being about 3 to about 20 weight percent and preferably about 10 to about 3 17 weight percent based upon the total weight of the binder present in the photographic composition.

The improved physical properties of the photographic compositions include increased covering power of developed silver, decreased density loss on drying, decreased dimensional changes and the like. Said improved physical properties are unexpectedly obtained by the presence of only a minor amount, for example, up to about 20 weight percent, based on the weight of the vehicle or binder in the composition, e.g. a photographic emulsion, of a polymer, e.g. a homoor copolymer having recurring units of Formula I set forth before.

A significant feature of this invention is a method whereby the presence of said polymer in an effective concentration, for example, up to 20% based upon the emulsion binder in a photographic element containing a lightsensitive silver halide emulsion, affords improved covering power and decreased loss of density upon drying without softening of the emulsion.

Accordingly, it is an object of this invention to provide improved light-sensitive emulsions comprising a hydrophilic colloid exhibiting improved covering power, decreased density loss on drying, and decreased dimensional change without adversely affecting desired sensitometric characteristics, or the hardness of said emulsions.

It is also an object to provide novel polymers comprising N- [tris(hydroxymethyl)methyl] acrylamide units such as copoly(2-acrylamido-Z-hydroxymethyl-1,3-propanediolacrylamide),

copoly(Z-acrylamido-Z-hydroxymethyl-1,3-propanediol-N-vinyl pyrrolidone) copoly[2-acrylamido-2-hydroxymethyl-1,3-propanediol-N-(Z-hydroxyethyl) acrylamide] and the like.

:It is a further object to provide for use in said proccsses, novel compositions which impart improved covering power, decreased density loss on drying and other useful properties without softening the photographic emulsion coating.

DESCRIPTION OF THE PREFERRED EMBODIMENTS oncm-o-omofi HaOH I. where R is hydrogen, methyl or ethyl.

In a preferred embodiment of the invention, a homopolymer consisting of recurring units as described above, when added to light-sensitive photographic emulsions at a concentration of from about 10 percent to about 17 percent by weight, based on the weight of total binding agent present, imparts the desirable characteristics set forth above to said emulsions. These photographic emulsions comprise a light-sensitive material, for example, silver halides such as silver chloride, silver bromide, silver chlorobromide and the like. Said emulsions can have a binding agent which is all gelatin, all non-gelatin, gelatin v 4 and a soluble extender polymer system or gelatin and latex polymer, or combinations of gelatin, latex and soluble polymers, as set forth herein.

In another preferred embodiment, a physical admixture of (1) a homopolymer consisting of recurring units of Formula I above and (2) a polymeric covering power addendum of the type described hereinbefore, in a total admixture concentration of from 10 to 17 weight percent based on the weight of total binding agent, imparts to silver halide photographic emulsions the desirable properties set forth above without adversely affecting the hardness of said emulsions. The admixture component derived from Formula I desirably constitutes at least 30 percent by weight of said physical admixture.

In still a further preferred embodiment of our invention, we provide copolymers which comprise units of an ethylenically unsaturated monomer, whose homopolymers impart good covering power and reduced density loss on drying in photographic silver halide emulsions, combined with units having Formula I. This combination provides not only good covering power and other beneficial photographic properties but also the unexpected and added desirable property of maintaining the hardness of the emulsion coating despite the usual characteristic of the homopolymer to soften the emulsion coating. Particularly good results are achieved with said copolymers when the component having Formula I constitutes at least 30 percent by weight of the total weight of said copolymers. Said copolymers are advantageously added to photographic silver halide emulsions in a concentration of from 10 to 17 percent by weight based on the total weight of binding agent employed.

In still another embodiment of our invention, our normally solid N-(trimethylol methyl) acrylamide polymers are present in various forms such as, for example aqueous solutions which are most conveniently used in emulsion manufacture.

It is known that certain polymers such as the water soluble high polymers like polyacrylamide, polysaccharides such as dextran, and the like, advantageously increase covering power and inhibit density loss on drying when incorporated in photographic silver halide emulsions. Unfortunately, the above-described effects are not achieved without concomitant unwanted and sometimes excessive softening of the emulsion coatings.

We have now unexpectedly found that physical admixtures of a poly[N-(tris(hydroxymethyl)methyl)acrylamide] used in the practice of our invention with any one of the polymeric addenda referred to hereinabove impart improved sensitometric and physical characteristics to photographic compositions without the excessive softening resulting when the respective polymeric addenda are used alone. Generally, said improvements in covering power, inhibition of density loss on drying and reduction of softening of the emulsion are imparted to photographic compositions comprising (1) all-colloid binders such as for example, gelatin, (2) non-gelatin binders such as poly (vinyl alcohol) and (3) a binder comprising a mixture of gelatin with a soluble or latex polgneric extender, such as copoly (ethyl acrylate-acrylic aci Copolymers which are suitable for the practice of this invention include those comprising monomeric units of Formula I above with monomeric units derived from other ethylenically, preferably monoethylenically unsaturated polymerizable monomers. Such other ethylenically unsaturated monomers are preferably those which form homopolymers which increase covering power when added to a photographic silver halide emulsion, e.g. acrylamide; but which homopolymers tend to soften the emulsion coating, such copolymers effect a marked reduction in softness, :but to a large measure, retain the good covering power generally associated with the homopolymer. Exemplary of the monomeric N-[tris(hydroxymethyl)methyl]acrylamides useful in preparing said copolymers are 2 acrylamido 2-hydroxymethyl-l,3-propanediol, 2 methacrylamido-Z-hydroxymethyl-1,3-propanediol, and the like. Examples of ethylenically unsaturated monomers which can be copolymerized with said N-substituted acrylamides are N-(2-hydroxyethyl)- acrylamide, acrylamide, vinyl pyrrolidone, and N-acrylylmorpholine.

We have also found that mixtures of a poly[N-(tris- (hydroxylmethyl)methyl)acrylamide] with polyvinyl half esters of dicarboxylic acids such as those of succinic, maleic, and the like or polymers containing repeating units derived from a vinyl 13-hydroxyethylcarbamoylalkylcarbamate are effective in practicing our invention. One such example is succinoylated poly(vinyl alcohol) which is conveniently admixed with poly(2 acrylamido 2-hydroxymethyl-1,3-propanediol) In another example photographic silver halide emulsions containing a physical admixture of po1y(vinyl )3-hydroxyethylcarbamoylmethylcarbamate) and poly(2-acrylamido-Z-hydroxymethyl-1,3- propanediol) exhibit less emulsion softness than poly- (vinyl fl-hydroxyethylcarbamoylmethylcarbamate) when used alone.

Preparation of the N-[tris(hydroxymethyl)methyl] acrylamides whose homoand copolymers comprise the novel compositions and emulsions used in practicing our invention can be effected by any of the methods known in the art such as, for example, by the reaction described in Abstr. of the Prague Polymer Conference, (1965), Iedlinski and Paprotny Reprint, page 483.

The temperature at which the homoand copolymers described herein are prepared is subject to wide variation since this temperature depends upon such variable features as the specific monomer used, duration of heating, pressure employed and like considerations. However, the polymerization temperature generally does not exceed about 100 C., and most often it is in the range of about 50 to about 100 C. The polymerization can be carried out in a suitable vehicle, for example, water or mixtures of water with water miscible solvents, as exemplified by methanol, ethanol, propanol, isopropyl alcohol, butyl alcohol, and the like. The pressure employed in the polymerization, if any, is usually only sufiicient so as to maintain the reaction mixture in liquid form, although either superatrnospheric or subatmospheric pressures can be used. The concentration of polymerizable monomer in the polymerization mixture can be varied widely wlth concentrations up to about 40%, by weight, and preferably about 8 to about 25%, by weight, based on the weight of the vehicle, being satisfactory. Suitable catalysts for the polymerization reaction include, for example, the free radical catalysts, such as hydrogen peroxide, cumene hydroperoxide, water soluble azo type initiators and the like. In redox polymerization systems the usual ingredients can be employed. If desired. the polymer can be isolated from the reaction vehicle by freezing, salting out, precipitation or any other procedure suitable for this purpose.

The binding agent employed in the silver halide emulsions of the invention can comprise any waterpermeable hydrophilic colloid commonly employed and/ or combinations thereof. These include, for example, gelatin, colloidal albumin, polysaccharides, cellulose derivatives, synthetic resins such as polyvinyl compounds, including poly(vinyl alcohol) derivatives, acrylamide polymers and the like.

The water-soluble polymeric additives used in our invention have also been found to be elfective when the vehicle or binding agent contains, in addition to the water-permeable, hydrophilic colloids aforementioned, still other colloids such as water insoluble polymer latexes for example dispersed polymerized vinyl compounds, particularly those which increase the dimensional stability of photographic materials.

Suitable copolymers which can be used as partial substitute binding agents according to this invention are acrylic copolymers, i.e., those copolymers prepared from polymerizable acrylic monomers containing the characteristic acrylic group,

Such polymers are conveniently prepared, for example, by the copolymerization of an acrylic monomer with at least one dissimilar monomer which can be another acrylic monomer or some other different polymerizable ethylenically unsaturated monomer. Preferably, the acrylic copolymers employed as gelatin substitutes in the practice of this invention are compatible with hydrophilic colloids such as gelatin itself and have a Tg of less than about 20 C. (Tg can be calculated by diiferential thermal analysis as disclosed in Techniques and Methods of Polymer Evaluation, volume 1, Marcel Dekker Inc., New York, 1966.) The term Tg is understood to be a time dependent, kinetic phenomenon represented by a transition temperature at which substantial segmental mobility of the copolymer structure is achieved. The temperature at which the thermodynamic characteristics are assumed by the copolymers particularly useful in our invention, within a given time, has been found to be not more than about 20 C.

In one embodiment, preferred copolymer binding agents which can be used in this invention comprise units of an alkyl acrylate such as, for example, methyl, acrylate, ethyl acrylate, propyl acrylate, butyl acrylates (e.g., nbutyl or t-butyl acrylates), arnyl acrylates, hexyl acrylates and the like. In addition, We have found that acrylic copolymers containing units of acrylic acid or a sulfoester acrylate are especially useful in the process. Typical polymers of this type are copoly(butyl acrylate-acrylic acid), copoly(methyl acrylate-acrylic acid), copoly(ethyl acrylate-acrylic acid), copoly(butyl acrylate-3-acryloyloxypropane-l-sulfonic acid, sodium salt) and the like, as disclosed in Dykstra US. Pat. No. 3,411,911 issued Nov. 19, 1968. In a preferred embodiment, the copolymer comprises up to about 30 percent by Weight of acrylic acid, a sulfonic acid acrylate or the sulfoester acrylate; especially good results are obtained with latex alkyl acrylate copolymers having up to about 30 percent, by Weight, of the acrylic acid or the sulfoester acrylate. High ratios of solubilizing groups, such as the acrylic acid groups or the sulfoester groups, produce a more soluble solution type polymer with respect to Water carrier solvents. In addition to these and other copolymers, i.e. products of a polymerization process, physical admixtures of the more soluble solution-type polymers and the latex polymers can also be used effectively within the scope of this invention to achieve the desired emulsion characteristics.

In another embodiment of this invention, the abovementioned copolymeric binding agents contain units of a third monomer. Exceptionally good results are obtained in the practice of this invention when the synthetic polymers comprise units of (1) alkyl acrylates, (2) acrylic acid or sulfoester acrylates, and (3) an acrylic monomer unit having an active methylene group in a side chain such as, for example, in a malonic ester group, an acetoacetic ester group, a cyanoacetic ester group or 1,3-diketone groups as disclosed in Smith Belgian Patent 712,829 issued Apr. 30, 1968. Typical polymers of this class include copoly(ethyl acrylate-acrylic acid-Z-acetoacetoxyethyl methacrylate), copoly(butyl acrylate-sodium 3- acryloyloxypropane 1 sulfonate 2 acetoacetoxyethyl methacrylate), copoly(methyl acrylate-sodium acryloyloxypropanesulfonate 2 acetoacetoxyethyl methacrylate), copoly(butyl acrylate-acrylic acid 2 cyanoacetoxyethyl methacrylate) and the like and mixtures thereof. The copolymers of (1) alkyl acrylates and (2) acrylic acid or the sulfoester can also contain units of (3) sulfobetaines, N methacryloyl N glycylhydrazine hydrochlorides, 2 [2 methacryloyloxyethyl] isothiuronium methanesulfonate and the like. Typical copolymers having sulfobetaine units include copoly(butyl acrylateacrylic acid 4,4,9 trimethyl 8 oxo 7 oxa 4- azonia-9-decene-l-sulifonate) and the like.

In still another embodiment of this invention, when the above-mentioned copolymeric binding agents contain a third monomer, said monomer can advantageously be chosen from monomers which are copolymerizable with the acrylates, methacrylates and sulfoesters set forth hereinbefore, i.e. different unsaturated, polymerizable compounds containing one or more CH=C groups and/ or more particularly, one or more CH =C groups, as disclosed in Dykstra U.S. Pat. No. 3,411,911, referred to hereinabove. Useful gelatin substitutes are, therefore, copolymers of the acrylates, methacrylates and sulfoesters as described above, with other polymerizable monomers comprising an ethylenically unsaturated moiety which form water insoluble addition polymers such as vinyl esters, amides, nitriles, ketones, halides, ethers, ore-unsaturated acids or esters thereof, olefins, diolefins and the like, as exemplified by acrylonitrile, methacrylonitrile, styrene, a-methylstyrene, vinyl chloride, vinylidene chloride, methyl vinyl ketone, vinyl acetate, fumaric, maleic and itaconic esters, 2-chloroethyl vinyl ether, methylenemalonitrile, acrylic acid, methacrylic acid, dimethylaminoethyl methacrylate, N-vinylsuccinimide, N-vinylphthalimide, N-vinylpyrrolidone, butadiene, isoprene, 'vinylidene cyanide and the like. The nature of the different polymerizable, ethylenically unsaturated compound which is copolymerized with the acrylates, methacrylates and sulfoesters to form the gelatin substitute is subject to wide variation. However, the copolymers used in this invention can contain from about to about 20%, by Weight, of such additional monomer, in polymerized form. Generally, the copolymers employed in the practice of this invention have a molecular weight in the range of about 5,000 to about 500,000 or more.

Further, those copolymers comprising the recurring units as shown hereinbefore in Formula I exhibit an inherent viscosity in water in a range of from about 0.08 to 0.6 and preferably in a range of from about 0.15 to about 0.5 at a concentration of 0.25 g. per 100 ml. of solution.

The novel compositions and emulsions of the invention can be made in various ways. In a practical aspect, a light-sensitive silver halide or mixture of such halides is precipitated in an aqueous binding agent solution. To the precipitated silver halide emulsion, which can be washed in any known way, can be added other emulsion adjuvants, and the emulsion then digested. To the thus digested emulsion is added an aqueous solution of the polymeric compounds or physical mixtures used in practicing this invention; when a uniform mixture has been obtained, the resulting emulsion can be coated onto a suitable support.

The photographic compositions of the invention can be coated on a wide variety of supports. Typical supports include polymeric films such as cellulose acetate film, polyvinyl acetal film, polystyrene film, polypropylene film and other polyolefin film, polycarbonate films, polyethylene terephthalate film and other polyester film as well as glass, paper, wood and the like. Supports such as paper, which are coated with alpha-olefin polymers, particularly polymers of alpha-olefins containing 2-10 carbon atoms as exemplified by polyethylene, polypropylene and ethylene-butene copolymers and the like, can also be employed.

The emulsions of this invention which contain the polymer additives disclosed herein can be chemically sensitized with compounds of the sulfur group, noble metal salts such as gold salts, reduction sensitized with reducing agents, and combinations of these. Furthermore, emulsion layers and other layers present in photographic elements made according to this invention can be hardened with any suitable hardener such as aldehyde hardeners, aziridine hardeners, hardeners which are derivatives of dioxane, oxypolysaccharides such as oxystarch, oxy plant gums, vinylsulfonyl ethers, and the like. The emulsions (containing the polymeric additives disclosed herein) can also contain additional additives, particularly those known to be beneficial in photographic emulsions, including, for example, stabilizers or antifoggants, particularly the water-soluble inorganic acid salts of cadmium, cobalt, manganese, and zinc as disclosed in U.S. Patent 2,839,405 of Jones issued June 17, 1958, the substituted triazaindolizines as disclosed in U.S. Patents 2,444,605 of Heimbach and Kelly issued July 6, 1948, and 2,444,607 of Heimbach issued July 6, 1948, speed-increasing materials, plasticizers and the like. In addition, these emulsions can be used in Xray and other non-optically sensitized systems and in orthochromatic, panchromatic and infrared sensitive systems. The sensitizing addenda can be added to photographic systems before or after any sensitizing dyes which are used. Some sensitizers which give particularly good results in the photographic compositions disclosed herein are the alkylene oxide polymers which can be employed alone or in combination with other materials, such as quaternary ammonium salts, as disclosed in U.S. Patent 2,886,437 of Piper issued May 12, 1959, or with mercury compounds and nitrogen-containing compounds, as disclosed in U.S. Patent 2,751,299 of Carroll issued June 19, 1956. Y

The following examples are included for a further understanding of the invention.

EXAMPLE 1 In a three-liter flask fitted with a thermometer, stirrer and dropping funnel are placed in 1.6 liters of water and 1012 g. (8.36 mols) of 2-amino-2-hydroxymethyl-1,3- propanediol. The internal temperature is brought to 0 C. by external cooling. To this solution is added dropwise 322 ml. (4.18 mols) of acrylyl chloride at such a rate that the internal temperature never exceeds 5 C. During the entire addition, the reaction mixture is vigorously stirred.

After addition is complete, the reaction mixture is stirred an additional 2 hours at room temperature, followed by refrigeration overnight at 0 C. The product, 2-acrylamido-2-hydroxymethyl 1,3 propanediol, is removed by filtration and recrystallized from a methanolethyl acetate solution (20/ by volume) afliording 521 g. (71%), M.P.138-139 C.

EXAMPLE 2 To a stirred solution of 89 g. (1 mole) of 2-amino-1- butanol in 200 ml. of acetonitrile, cooled to 0 C., is added dropwise 45 g. (0.5 mole) of acrylyl chloride during a 1.5 hour period keeping the temperature between 05 C. After addition is complete, the reaction mixture is allowed to reach room temperature. The solid is removed by filtration, washed several times with fresh changes of acetonitrile, and the filtrate concentrated under reduced pressure. There is obtained 96.0 g. of a yellow medium viscosity oil, 1-acrylamido-l-hydroxymethylpropane, which is used directly for the homoand copolymerizations.

EXAMPLE 3 To 400 ml. of water are added 242 g. (2 moles) of 2- amino-Z-hydroxymethyLl,3-propanediol and 3 g. of sodium nitrite inhibitor. This solution is cooled to 5 C. whereupon 104.5 g. (1 mole) of methacrylyl chloride is slowly added keeping the temperature below 10 C. After addition is complete, the reaction mixture is allowed to reach ambient temperature.

The reaction mixture is poured into acetone and the resulting slurry filtered to remove the insoluble ammonium salts. The water is removed under reduced pressure leaving a light yellow oil. The oil is again poured into acetone, the acetone solution is filtered and the acetone removed under reduced pressure. Recrystallization from acetonitrile affords 105.2 g. (50.6 percent) of 2-methacrylamido-Z-hydroxymethyl-l,3-propanediol, M.P. 86-88 C.

EXAMPLE 4 To a solution of 124 g. (2.02 moles) of ethanolamine in 120 ml. of acetonitrile, cooled to 2 C. in a salt-ice mixture, is added 90.5 g. (1.0 mole) of acrylyl chloride while stirring. The rate of addition is such as to keep the temperature of the solution at about 5 C. After the addition is complete, the mixture is stirred in the ice bath for 1.7 hours. The amine salt is removed by filtration and rinsed with 100 ml. of acetonitrile. After removal of the solvent, the residue is distilled in a molecular still to give 68.5 g. of N-(2-hydroxyethyl)acrylamide distilling at 8 mercury pressure, pot temperature 93 C. to 6p. mercury pressure, pot temperature 107 C., N 1.5040--N 1.5050.

EXAMPLE 5 N-hydroxymethylacrylamide is synthesized from acrylamide and formaldehyde as described by H. Wohnsiedler and P. Adams, U.S. Patent 2,864,861. Recrystallization from methylene chloride and then from s-dichloroethane gives material of MP. 72.5-75 C.

EXAMPLE 6 To 1.2 liters of a water-isopropanol solution (70/30 by volume) is added 300 g. of 2-acrylamido-2-hydroxymethyl-1,3-propanediol, prepared according to the procedure of Example 1. To this solution is added 5 ml. of a 35 percent hydrogen peroxide solution and the resulting mixture is placed in a constant temperature bath at 90 C. under a reflux condenser.

After 3 hours, the viscous, colorless solution is allowed to reach room temperature and then it is poured into stirred acetone. After two washes with changes of fresh acetone, the polymer is removed by filtration and dried under vacuum. There is obtained 295 g. of a white polymer, poly(2acrylamido-2-hydroxymethyl 1,3 propanediol), with an inherent viscosity in water of 0.18 at a concentration of 0.25 g. per 100 ml. of solution.

Unless otherwise stated, all inherent viscosities are determined at a concentration of 0.25 g. of polymer in 100 ml. of solution, regardless of the choice of solvent. The infrared spectrum shows a strong band at 3400 cm.- (OH), and a sharp band at 1640 cm.- (amide 0 0).

Analysis.Calcd. for C H NO (percent): C, 48.0; H, 7.5; N, 8.0. Found (percent): C, 48.2; H, 7.9; N, 7.7.

EXAMPLE 7 To 600 ml. of a water-isopropanol solution (70/30 by volume) are added 55.0 g. of 2-methacrylamido-2-hydroxymethyl-1,3-propanediol, prepared as in Example 3, and 0.5 ml. of a 35 percent hydrogen peroxide solution. The resulting solution is refluxed overnight on a steam bath and then concentrated to one-half volume under reduced pressure. The polymer is precipitated by pouring the clear aqueous dope into acetone with stirring. The material is washed twice with changes of fresh acetone, filtered, and dried in a vacuum oven at 60 C. 33.6 grams of dry polymer, po1y(Z-methacrylamido-2-hydroxymethyl-1,3-propanediol), is obtained. The inherent viscosity in water is 0.11.

The infrared spectrum of the polymer shows strong bands at 3400 cm. (--OH) and 1660 cm. (amide c=o AnaZysis.--Calcd. for C H NO (percent): C, 50.8; H, 7.9; N, 7.4. Found (percent): C, 50.3; H, 7.9; N, 6.5.

EXAMPLE 8 The procedure of Example 6 is used to prepare poly(lacrylamido 1 hydroxymethylpropane), poly[N (2- hydroxyethyl)acrylamide] and poly(N hydroxymethylacrylamide). In each instance an equivalent amount of their respective monomersi.e. 1 acrylamido 1 hydroxymethylpropane, N (2 hydroxyethy1)acry1amide 10 and N-hydroxymethylacrylamide are substituted for the 2 acrylamido 2 hydroxymethyl 1,3 propanediol employed in Example 6.

EXAMPLE 9 Into a 1 liter round bottom flask fitted with a condenser are placed 820 ml. of a solution composed of 70 parts water and 30 parts isopropanol (by volume), 100 g. (0.57 mole) of 2 acrylamido 2 hydroxymethyl 1,3- propanediol prepared as in Example 1 and 39.9 g. (0.57 mole) of acrylamide. To this solution is added 2.8 ml. of a 35 percent hydrogen peroxide solution and the resulting mixture is placed in a constant temperature bath at C.

After 16 hours, the viscous, colorless solution is allowed to reach room temperature and is poured into 4 liters of stirred acetone to precipitate the polymer. The tacky, white polymer becomes friable after two more washings with 2 liters each of acetone, while vigorously stirring for 2 hours, with each washing. Filtration, followed by drying in a vacuum oven for 72 hours at 40 0., gives 133 g. of copoly(acrylamide 2 acrylamido 2 hydroxymethyl 1,3 propanediol. The inherent viscosity in water is 0.18.

EXAMPLE 10 To 500 ml. of a water-isopropanol solution (70/30 by volume) are added 26.3 g. (0.15 mole) of 2-acrylamido- 2 hydroxymethyl 1,3 propanediol, prepared as in Example 1, 16.7 g. (0.15 mole) of N-vinylpyrrolidone and 1.5 ml. of a 35 percent hydrogen peroxide solution. The reaction mixture is refluxed in a constant temperature bath at 85 C. for 16 hours. The clear solution is concentrated to one-half volume under reduced pressure followed by precipitating the polymer from solution by pouring the dope into acetone. The polymer is washed twice with fresh changes of acetone, filtered and dried under reduced pressure at 60 to give 42 g. of copoly(2- acrylamido 2 hydroxymethyl 1,3 propanediol;N- vinyl pyrrolidone) with an inherent viscosity of 0.15 in water.

Analysis.Calcd. for C H N O (percent): C, 54.5; H, 7.7; N, 9.8. Found (percent): C, 53.4; H, 7.9; N, 9.6.

EXAMPLE 11 Into a 200 ml. flask fitted with a reflux condenser are placed 44 ml. of a water-isopropyl alcohol solution (1:1 by volume), 17.5 g. of 2 acrylamido 2 hydroxymethyl 1,3 propanediol, prepared as in Example 1, 11.5 g. of N-(2-hydroxyethyl)acrylamide, prepared as in Example 4, dissolved in ml. of water-isopropyl alcohol, and 0.50 ml. of a 35 percent hydrogen peroxide solution. The resulting solution is refluxed on a steam bath for 2 hours. The dope is cooled to room temperature and poured into 4 liters of stirred acetone to precipitate the polymer. The solid, copoly[2 acrylamido 2 -hydroxymethyl 1,3 propanediol;N (2 hydroxyethyl) acrylamide], is washed several times in fresh changes of acetone, filtered, and dried under a constantly applied vacuum.

EXAMPLE 12 Three separate medium speed silver bromoiodide gelatin negative emulsions are prepared and coated onto three photographic compositions (I, IV, and VI). Each portion is coated separately on a polyester support at 450 mg./ft. silver and 1248 mg/ft. gelatin. Additional coatings are identically made except that, before coating, the following polymers are added:

Coating II-SO g./silver mole of polyacrylamide Coating IH50 g./ silver mole of poly(2-acrylamido-2- hydroxymethyl-1,3-propanediol) Coating V-SO g./ silver mole of poly[N-(Z-hydroxyethyl) acrylamide] Coating VII -50 g./ silver mole of poly(N-hydroxy-methyl-acrylamide) Samples of each of these coated films are exposed in an Eastman IB Sensitometer, developed-for min. in Kodak DK-5O developer, fixed, washed and dried. The densities of the sensitometric strips are measured both before and after drying. The density change on drying is measured at a wet density of 1.6.

Samples of the films are also tested for softening of the emulsion coating. This measurement is made on the wet cotaing after each step of processing at 68 F. for 5 min. in Kodak developer DK-50, in fix and in water. The values listed in Table I represent the weight load of a stylus under which each coating is subjected before the emulsion becomes ploughed. The hard coating, therefore, is indicated by the high figure.

EXAMPLE 14 A medium speed silver bromoidide gelatin negative emulsion is prepared and coated (Coating I) on a polyester support at a coverage of 450 mg. silver per sq. ft. and 1248 mg. gelatin per sq. ft. An additional coating TABLE I Soitness values Coating Rel. Density number Addendum gJAg mole speed Gamma Fog change DK-SO Fix Water 1 100 1. 04 01 10 26 110 90 II 50g. polyacrylamide 116 1.13 .01 .05 11 50 51 III 60 g. poly(2-acrylamido-2-hydroxymethyl-1,3- 115 l. 12 .01 10 37 124 110 propanediol).

W n dr n 1 d] i ii?) '3; 2i 2% 1% V 60. 1N-2- oxet lacramie VI 8 p0 yl y y y y 100 .84 .01 13 25 114 73 VII 50 g. poly(N-hydroxymethylaerylamlde) 126 .99 .01 +.06 8 50 58 The above data in Table I indicates that poly(2-acrylamido-Z-hydroxymethyl-1,3-propanediol) improves covering power, eliminates density loss on drying and does not soften the emulsion. Polyacrylamide, poly[N-(2-hydroxyethyl)acrylamide] and poly(N hydroxymethyl acrylamide) improve covering power and control density loss on drying, but they each soften the emulsion coating.

EXAMPLE 13 (Coating II) is made in the identical manner as Coating I except that before coating 50 g. of polyacrylamide per silver mole is added. Other coatings (Coating III-VI) are made identically to Coating I except tht before coating poly(2 acrylamido-Z-hydroxymethyl-1,3-propanediol) is added in the following amounts:

Grams of polymer Coating No.: per silver mole III 20 IV 3,0 V 40 VI 50 TABLE III Soitness Coating Rel. Density value number Addendum gJ g mole speed Gamma Fog change DK-50 T 100 1. 01 14 37 II 50 g. polyacrylamlde 110 1. 23 01 11 22 g. poly(2-acrylam1do-2-hydroxymethyl-1,3-propanediol) 102 1. 20 01 -.0B 38 g. poly(2acryla1mdo-2hydroxymethyl-1,3-propanedill) 107 1. 20 .01 0 40 40 g. poly (2-acrylamido-2-l1ydroxymethy1-1,3-propanediol).. 110 1. 22 01 04 60 g. poly(2-acry1am1do-2-hydroxymethyl-l,3-propanediol) 105 1. 17 01 +.06 46 ings are made identically except that before coating the following polymers are added:

Coating II--50 g./silver mole of polyacrylamide Coating III-50 g./ silver mole of poly[2-acrylamido-2-hydroxymethyl-1,3-propanediol] Coating V50 g./silver mole of poly(N-hydroxymethylacrylamide) The latex polymer is prepared by the procedure of Example 5 of Dykstra US. Pat. 3,411,911 issued Nov. 19, 1968, referred to hereinbefore, except that an equivalent amount of butyl acrylate is substituted for the methyl acrylate in the example.

The coatings are exposed and processed and the photographic properties and softness values determined in the same manner as in Example 12. The results are set forth in Table H.

The results in Table III show that poly(2-acrylamide- 2-hydroxymethyl 1,3 propanediol) effectively provides covering power and controls density loss on drying in a gelatin silver halide emulsion over a wide range of concentrations without inducing softening of the emulsion coating.

EXAMPLE 15 TABLE II softness values Coating Rel. Density number Addendum gJAg mole speed Gamma Fog change Dk-BO Fix Water I Cnnfrnl 1. 01 01 -0. 17 39 146 133 II 60 g. polyacrylamide 1. 12 .02 0. 18 24 74 70 III 50 g. poly(2-aerylam1do-2-hydroxymethyl-1,3-propanediol)- 1. 06 01 0 41 117 110 IV on r 100 .75 .01 0. 17 23 130 V 50 g. poly(N-hydroxymethylacrylamide) 118 .92 .02 0. 14 10 60 61 13 identically as Coating I except that before coating poly(2- acrylamido-Z-hydroxymethyl-1,3-propanediol) is added in the following amounts:

Grams of polymer Coating No.: per silver mole 14 The water-soluble polymer is prepared according to the procedure of Example 7 of Smith, Belgian Patent 712,829 issued Apr. 30, 1968, referred to hereinbefore.

All of the above-described coatings are exposed, processed and tested in the same manner as Example 12. The

III 20 results are tabulated in Table V. IV 30 V 40 VI 50 TABLE V softness Coating Rel. Density value number Addendum gJAg mole speed Gamma Fog change DK-50 I 100 1.16 .01 -.05 51 r 50g. polyacrylamide 107 1. 24 .02 -.10 20 II 10 g.poly (2-acrylamido-Z-hydroxymethyl-1,3-propanediol) 105 1. 13 01 05 60 V g. poly(2-acrylamido-Zhydroxymethyl-l, B-propanediol).-- 97 1- 17 02 03 50 The polymeric latex is prepared according to the procedure of Example 5 of Dykstra US. Pat. 3,511,911 issued Nov. 11, 1968, referred to hereinbefore, except that an equivalent amount of butyl acrylate is substituted for the methyl acrylate in the example.

All of the above coatings are exposed, processedand tested in the same manner as Example 12. The results are shown in Table IV.

The data in Table V show that the incorporation of a compound of the invention in photographic silver halide emulsions, in which the vehicle consists of a combination of gelatin and a water-soluble polymer, tends to reduce density loss on drying without softening the emulsion or markedly decreasing covering power.

As previously set forth in this specification, we have found that homopolymers which improve covering power and reduce density loss on drying in photographic silver halide emulsions with attendant unwanted softening of TABLE IV softness Coating Rel. Density value number Addendum gJAg mole speed Gamma Fog change DK-fio I. 100 1. 11 01 18 44 50 g. polyacrylamide 105 1. 23 .01 20 22 III 20 g. poly(2aerylamido2-hydroxymethyl-1,3-propaned 105 1. 15 .01 10 43 IV g. poly(2aerylamido-2-hydroxymethyl-l,3-propanediol)-.- 102 1. 14 01 08 44 V-.. g. poly(Z-acrylamido-Z-hydroxymethyl-l,a-propanediol) 102 1. 14 01 .04 46 AI 50 g. poly (2-acrylamido-2-hydroxymethyl-1,B-propanediol).-- 100 1. 15 01 02 49 The above results indicate that poly(Z-acrylamido-Z- hydroxymethyl 1,3 propanediol) improves covering powe and controls density loss on drying in light sensitive silver halide emulsions in which the vehicle is a combination of gelatin and polymeric latex. Further, these advantageous properties are attained withno attendant softening of the emulsion coating.

EXAMPLE 16 A medium speed silver bromoiodide negative emulsion employing a combination of gelatin and an ethyl acrylateacrylic acid-acetoacetylester water-soluble polymer as the vehicle is prepared and coated (Coating I) on a polyester support at 450 mg. silver per sq. ft., 832 mg. gelatin per sq. gt. and 415 mg. water-soluble polymer per sq. ft. An additional coating (Coating II) is made in the identical manner as Coating I except that before coating 50 g. of polyacrylamide per silver mole is added. Two other coatings (Coatings III and IV) are made identically as Coating I except that before coating poly(2-acrylamido- 2-hydroxymethyl-1,3-propanediol) is added as follows:

Grams of polymer Coating No.: per silver mole EXAMPLE 17 Samples of polyacrylamide and poly(2-acrylamido-2- hydroxymethyl-1,3-propanediol) are added to separate portions of a medium speed silver bromoiodide gelatin negative emulsion at concentrations of 50 g. and 30 g. per mole of silver respectively. Similarly, physical mixtures of these polymers in which the weight of polyacrylamide is varied are added to separate portions of the above-described emulsion. Each sample of physical mixture is incorporated in the emulsion at 30 g. per mole of silver. The variations in weight percent of polyacrylamide are given in Table VI below. Each emulsion sample is coated on a poly(ethylene terephthalate) film support at a coverage of 450 mg. of silver per sq. ft. and 1248 g. of gelatin per sq. ft. A sample of each coating III 10 is exposed, processed and tested in the same manner as N 20 Example 12. The results are given in Table VI.

TABLE VI 1 wk. incubation Weight at 125, 50% percent relative humidity Soitness of polyavalue eryla- Rel. Rel. Density in Dk-EO Sample mide speed Gamma speed Gamma change developer Polyagrylsimi rln 112 1. 25 148 1. 21 -0. 07 20 Do. 33 1. 15 148 1. 12 -0. 05 32 Do- 50 118 1. 14 1. 11 -0. 06 32 D0- 67 112 1. 15 155 1. 15 -0. 12 27 D0- V 83 105 1. 14 141 1. 13 0. 12 23 Poly(2-aerylamido-2-hydroxymethyl-1,3-propanediol) 112 1. 02 159 1. 11 0 32 Control 100 1. 13 126 1. 04 -0. 12 29 EXAMPLE 1 8 TABLE Vm I Soft- The procedure of Example 17 1s repeated except that Adienriless um V8116 the gelatin is replaced by the combination of the gelatlny g BBL F Dave]- latex polymer used in 'Example 15 and the samples of Addendum 3 spew Gamma P l 2- lamido-2- poly(2 acrylam1do-2'hydroxymethyl-1,3-propaned1ol) 1s ig gfa 8th added at a concentration of 50 g. per mole of silver. propanedlol) g? 3: 3:23 fig :1 h ic lmix- I 102 2.20 .22 34 Further, the total weight of each sample of p ys a 10 Do n 105 2.68 28 ture is 50 g. per mole of silver. The results are shown Polyatigiilamdighplilis Poly(2- 8013 0- y OXY- in Table VII. methyl-1,3 pr0paned.iol) 5+5 100 2. s0 .23 o 10+10 94 2.40 .21 30 Control 100 2.10 .26 48 TABLE VII 1 wk. incubation Weight at 125, I percent relative humidity of poly- Softness acryla- Rel. Density value Sample mi 0 speed Gamma speed Gamma change DK-50 1 21 102 1.18 148 1.11 -0. 17 21 132 mm a as 1.10 148 1.02 -0.04 34 D5 50 100 1. 13 155 1. 06 -0. 07 32 Do 51 102 1. 14 155 1. 01 -0. 07 21 83 13% '52 it; it; 3 23 l'l gifiiifiql i z-hydmymethyl propane 100 1.05 125 0.98 -0. 10 40 EXAMPLE 20 EXAMPLE 19 Samples of polyacrylamide and poly(2-acrylamido-2- hydroxymethyl-1,3-propanediol) and physical mixtures of equal parts by weight of each of these compounds are added to separate portions of a coarse-grained high speed silver bromoiodide gelatin emlusion of the type used for screen X-ray materials and containing g. of gelatin Physical admixtures containing equal parts by weight and each of the following polymers: poly(vinyl pyrrolidone); poly(vinyl 5 hydroxyethylcarbamoylmethylcarbamate) synthesized according to Example 1 of Minsk et al. US. Pat. 3,392,151, issued July 9, 1968; dextran; and succinoylated poly(vinyl alcohol) synthesized according to Example 4 of Minsk et al. US. Pat. 3,165,412,

er mole of silver. Each emulsion sample is coat d on a 35 issued Ian. 12, 1965, are tested in an all-gelatin emulsion poly(ethylene terephthalate) film support at a coverage of emplTying t F Pgg 0f l p f I'l f iia zh sam e con ams ams 1' mo e o si ver 0 o 473 mg. of silver per sq. ft. and 480 mg. of gelatin per y y y 1,3 proPanedio1)l'-;mg(25. All of the coatmgs are exposed and processed 40 grams per mole of silver of homopolymer. The test results cording to the procedure of Barnes and Rees, Belgian are givenin T bl 1X,

TABLE IX 1 wk. incubation at F., 50% relative Fresh humidity Softness Compound Rel. Rel. Density value denumber Compound speed Gamma Fog speed Gamma Fog change veloper 1 Polyaerylamide.-. 126 1.15 .01 1. 09 .05 05 20 Poly(z-aerylamidp-2-hydroxymethyl-1,3-propenediol) 102 1. 03 01 123 99 05 13 43 Poly(vinylpyrrolldon 97 1. 02 01 126 1. 06 05 03 12 Poly(vinyl Z-hydroxyethylcarbamoylmethylcarbamate) 100 1. 13 01 1. 11 05 09 17 Dextran- 110 1. 05 01 110 1. 06 05 07 18 V1 Suceinoylated poly(vmyl alcohol) 118 1. 11 01 138 1. 04 05 03 29 Mixture of II and III 89 96 01 105 96 05 0 25 Mixture of II and IV 118 1. 11 01 135 1.07 05 05 22 Mixture of II and V 118 1. 12 01 115 1. 03 05 05 26 Mixture of II and VI. 123 1'. 20 01 141 1. 05 05 05 33 Cnnfrnl 100 1. 07 01 132 1. 02 05 07 34 Patent 700,301, issued Aug. 3 1, 1967. The sensitometric EXAMPLE 2 1 results and softness values are shown in Table VIII. It is seen that the compounds of this invention are also effective in fast photographic emulsions such as those X-ray The procedure of Example 20 is repeated except that the gelatin is replaced by the combination of gelatin and latex polymer used in Example 15. The results are set.

materials used m combmation w1th intensifying screens. forth m Table X.

TABLE X 1 wk. incubation at 125 F., 50% relative Fresh humidity softness Compound Rel. Rel. Density value denumber Compound speed Gamma Fog speed Gamma Fog change veloper Polyacrylnmide V 118 1. 08 01 118 95 05 14 22 Poly(2 acrylamido-2-hydroxymethyl-l 3-propanediol) 112 96' 01 126 95 05 01 60 Poly(v1nylpyrrol1done) 82 1. 13 01 120 1.02 O5 07 22 Poly(vmyl 2-hydroxyethylcarbamoylmethylcarbamat 118 1. 03 01 159 1. 07 05 08 28 Dextran- 118 1. 03 01 112 1. 03 05 13 32 Succmoylated poly(vmyl alcohol) 129 1.03 .01 138 .88 05 04 51 Mixture of II and III 7 71 96 01 78 80 05 15 34 Mixture of II and IV. 118 1. 00 01 112 89 05 05 36 Mixture of II and V- 107 1. 02 01 123 95 05 06 42 Mixture of II and VI 132 a 1. 05 01 141 93 05 0 56 Control- 100 99 01 102 84 05 15 55 amples 22 and 23 and Tables XI and XII which follow.

From these tables, it is seen that samples containing the 18 EXAMPLE 23 The steps of procedure of Example 22 are repeated except that the gelatin is replaced by the combination of gelatin latex polymer used in Example 21. The results are 5 presented in Table X II.

EXAMPLE 24 Similar results are obtained when the copolymers described in Example 22 are tested by the procedure of Example 19 in a coarse-grained fast gelatin silver bromoiodide photographic emulsion of the type customarily used for X-ray materials.

TABLE XII 1 wk. incubation at 125 F., Fresh relative humidity Moi softness percent Rel. Rel. Density value comonomer speed Gamma Fog speed Gamma Fog change developer N-(2-hydroxyetl1yDacrylamide (comonomcr) 36 107 123 97 07 51 Control 100 102 86 17 59 N-vinylpyrrolidone (comonomcr) 45 82 90 05 48 Contr 87 88 i4 60 Acrylamide (comonomer) 50 132 1. 05 06 36 Control. 100 138 0. 95 17 Polyacrylamir'in 1. 15 138 1. 0O 18 17 Control 100 90 13 50 EXAMPLE 22 Samples of 2-acrylamido-2-hydroxymethyl-1,3-propanediol copolymerized with acrylamide, N-vinylpyrrolidone and N-(Z-hydroxyethyl)acrylamide are tested photo- 35 graphically in an all-gelatin emulsion as in Example 12. The results are presented in Table XI.

The invention has been described in detail with particular reference to certain preferred embodiments thereof, but it will be understood that variations and modifications can be eifected within the spirit and scope of the invention.

30 We claim:

1. Water soluble, normally solid copoly(2-acrylamido- 2-hydroxymethyl-1,3-propanediol-acrylamide) 2. Water soluble, normally solid copoly(2-acrylamido- 2-hydroXymethyl-1,3-propanediol-N-vinyl pyrrolidone).

3. Water soluble, normally solid copoly[2-acrylamido- 2-hydroxymethyl-1,3-propanediol N (2-hydroxyethyl)- acrylamide] TABLE XI 1 wk. incubation at F., 50%

Fresh relative humidity Moi softness percent Rel. Rel. Density value comonomer speed Gamma Fog speed Gamma Fog change developer N-(Z'hydroxyethyI) acrylamide (comonomer) 36 97 1. 16 01 107 1. 04 .05 0 30 Control 100 1. 04 01 100 93 05 05 28 N-vmyipyrroiidone (comonomer) 45 118 1. 18 01 120 107 04 04 32 Control 100 1. 1O 01 120 96 09 26 Acrylamide (comonomer) 110 1. 19 151 1. 10 O 41 Control 100 1. 12 138 1. 12 12 37 Polyacrylarnida 107 1. 21 1. 15 08 20 Control 100 1. 13 126 1. 04 05 32 References Cited UNITED STATES PATENTS 4/1965 Minsk 96-114 JAMES A. SEIDLECK, Primary Examiner S. M. LEVIN, Assistant Examiner US. Cl. X.R.