CH616440A5 - Process for the preparation of a latex composition filled with a hydrophobic compound - Google Patents

Abstract

An initial latex of a synthetic polymer is gradually poured, with stirring, into a solution of a hydrophobic compound in a water-miscible solvent. On precipitating, the hydrophobic compound is bound into and onto the micelles of the latex. Thermal analysis curves of the dried latexes are different: "A": filled latex; "B": initial latex. Such a latex filled with a chromogenic coupler compound is employed for the preparation of photographic emulsion coatings with silver salts containing a chromogenic coupler. <IMAGE>

Description

The present invention relates to liquid compositions simultaneously containing at least one hydrophobic compound and an aqueous suspension of polymer, that is to say a latex, the hydrophobic compound or all of the hydrophobic compounds being very finely dispersed in the micelles. of this latex. It relates to these compositions in themselves, hereinafter called "charged latexes", a process for preparing them and, as an application of these compositions, layers of these compositions, applied to a support. The invention can be used, in particular for the preparation of photographic silver halide emulsions containing a latex loaded with a dye-forming coupler, which is a hydrophobic compound, this latex being dispersed in gelatin keeping the halides of silver.

Several industrial techniques make it possible to disperse hydrophobic compounds, in particular non-polymeric compounds such as dye-forming couplers, absorbents of ultraviolet, various hydrophobic additions for layers of gelatin or other hydrophilic colloids, by obtaining a distribution. , more or less uniform, in particular for preparing photographic emulsions. One of the simplest consists in mechanically mixing, roughly, all of the hydrophobic compounds, liquid or solid, with an appropriate colloidal emulsion or suspension, then passing the mixture thus obtained through a high-energy mill, such as a mill. with colloids, (sometimes called a colloid mill); this operation is repeated several times. Less fine dispersions are thus prepared than those which can be obtained by other means, and the dispersions obtained are often unstable. This technique consumes a lot of energy to obtain a suitable reduction in particle size and a suitable dispersion. This high energy consumption is often accompanied by the release of heat, which can be localized undesirably by chemically degrading certain constituents of the composition.

US Patents 2,304,940 and 2,322,027 describe another technique for dispersing hydrophobic compounds through a solution or dispersion of a hydrophilic colloid, which will later be deposited as a layer, finally forming a hydrophilic colloid layer in which the hydrophobic compounds are dispersed. This technique consists in initially forming a solution by dissolving the hydrophobic compound or the hydrophobic compounds in oils or in solvents having high boiling points, then in dispersing the oily solution thus obtained in the solution or dispersion of hydrophilic colloid. According to a variant, described in US Pat. No. 2,801,171, an auxiliary solvent, having a small molecular weight, is used to facilitate the dissolution of the hydrophobic constituents in the oily solvent: as auxiliary solvents, for example, ethyl acetate or a small molecular weight ketone.

The processes using these auxiliary solvents, oily and having high boiling points, are widely used in the preparation of photographic products, intended for color photography and containing, in dispersion, heavy dye-forming compounds, sometimes called ballasted couplers . However, the dispersion of these coupler solutions

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requires great energy to obtain very fine particles which are perfectly dispersed, and this generally results in an undesirable degradation of certain constituents of the composition. This dispersing is a long and costly operation. For many years, attempts have been made to disperse hydrophobic compounds such as ballasted couplers in photographic emulsions, or other dispersions or solutions containing hydrophilic colloids under better conditions, as regularly as possible. We sought in particular to eliminate the shredder consuming a lot of energy.

Although the present invention uses certain polymeric latexes in combination with dispersions of hydrophobic compounds to form layers or compositions, of the type used in photography, these latexes are used very differently from the known methods.

It is known, in particular, to use latexes only as a means for providing a polymer component in a layer which is going to be deposited. Latexes have often been simply mixed with photographic emulsions which generally contain gelatin, silver halide and various well-known auxiliary compounds. When organic solvents and hydrophobic compounds such as dye-forming couplers have been used in combination with synthetic polymers to prepare coating compositions, the hydrophobic compound and the polymer have often been dissolved simultaneously in the solvent before introducing the solvent. everything in the other constituents of the coating composition, as indicated, for example, in U.S. Patents 2,269,158, 3,518,088 or 3,619,195. U.S. Patent 2,772,163 relates to the use of certain latexes in combination with ballast couplers soluble in basic medium, described in patent of the United States of America 2,376,679. These couplers are dissolved in basic solutions, and these couplers are precipitated by neutralization . The latex used in US Pat. No. 2,772,163 is fundamentally different from that used according to the invention, since it is not a "loaded" latex, as specified below. The present invention has a much more general scope than that of this patent because it applies to very varied hydrophobic compounds; on the other hand, it allows much larger proportions of hydrophobic products to be introduced into latex particles.

The new charged latexes are dispersions of polymers whose dispersed or discontinuous phase (or micellar phase) consists essentially of particles of a synthetic polymer, in which are dispersed on the surface or in depth, very small particles of one or more hydrophobic compounds. To prepare these dispersions by the process according to the invention, an initial latex and a solution of the hydrophobic compound or the hydrophobic compounds are mixed in a solvent or a mixture of solvents miscible with water. The term “dispersed”, applied to the particles of hydrophobic compounds, means here “associated” with the micelles of the initial latex both by surface fixation and by penetration into the mass of the micelles. The invention makes it possible to prepare products formed from a support covered with at least one layer in which micelles of latex thus loaded are dispersed.

It is possible to prepare charged latex compositions for photographic use, which are a particularly useful embodiment of compositions according to the invention, by a process in which the initial latex, which can be charged, is gradually added (as specified below). ) to a solution of the hydrophobic compound or of a set of hydrophobic compounds in a solvent or mixture of solvents miscible with water. The order of addition is of fundamental importance: the latex must be poured into the solution of hydrophobic compounds in order to prevent coagulation of the latex and to prevent the precipitation of too large a quantity of hydrophobic compound outside the micelles of the latex. .

The essential objects of the invention are:

(1) a process for preparing a latex composition of loaded polymer, having a dispersed phase which essentially consists of micelles of a latex loaded with at least one hydrophobic compound dispersed in this polymer, characterized in that one introduces gradually, in a solution of the hydrophobic compound in at least one organic solvent miscible with water, an initial latex which can be charged and an amount of water at least sufficient for the hydrophobic compound to become insoluble in the solution, this amount of water being provided by the initial latex, or by the latter and a make-up water.

(2) a charged latex composition prepared by this pro-

i s sold; in this composition, the micelles of the latex are formed from a synthetic polymer at the surface of which and / or in the mass of which is dispersed at least one hydrophobic compound, the mass ratio hydrophobic compound / polymer being between 1/4 and 3 / 1 and the mean diameter of the charged micelles 2i) being between 20 nm and 200 nm; and

(3) the use of this composition in a photographic product containing a silver halide and at least one layer prepared from such a composition.

According to various advantageous embodiments, this method has the following particularities:

(a) all of the water is supplied by the initial latex;

(b) the total time of addition of the latex is at least about ten seconds;

(c) at least half of the organic solvent is separated from the composition obtained by adding the initial latex to the solution of the hydrophobic compound;

(d) after elimination of the water-miscible solvent, the loaded latex composition is deposited on a support, then it is dried to obtain a composition in solid layer, the amount of

“Hydrophobic compound thus dispersed being at least about 2/100 of the mass of the dispersed phase of the composition at the time of deposition on the support;

(e) the micellar phase of the initial latex is essentially formed of a copolymer compatible with gelatin and containing

4o nant units of at least two ethylenic comonomers, about 2/100 to about 25/100, by mass, of this copolymer being formed of units of a comonomer containing free or salified sulfonic acid groups;

(f) the micellar phase of the initial latex is essentially formed of a copolymer comprising the following units (mass proportions): (a) from approximately 75/100 to approximately 98/100 of ester of monomer formula R-CH = C (—R ') -COOR' where R denotes a hydrogen atom or a lower alkyl group, R 'denotes a hydrogen atom or a methyl group and R "

su denotes an aliphatic group having from one to six carbon atoms; (b) from about 2/100 to about 25/100, of a hydrophilic ethylenic comonomer containing a carboxylic or sulfonic group and having a molecular mass at most equal to about 300.

(G) the copolymer comprises the following units (mass proportions); from about 80/100 to about 95/100 of the comonomer (a); from about 2/100 to about 10/100 of the comonomer

(b); and from about 2/1000 to about 100/1000 of a comonomer

(c) ethylenic and having at least one crosslinkable group;

(H) comonomer (a) is methyl, ethyl, propyl or butyl acrylate or methacrylate; comonomer (b) has a terminal sulfonyl group; and the comonomer (c) comprises an active methylene group;

f, 5 (i) the water-miscible solvent is acetone, ethyl, methyl or isopropyl alcohol, methyl ethyl ketone, tetrahy-drofuran, dimethylformamide, N-methylpyrrolidone, dimethyl sulfoxide or a mixture between these compounds.

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It is assumed that a large number of the useful results which can be obtained by the implementation of the invention result directly from the exceptional physicochemical modifications occurring during the mixing characteristic of the process according to the invention: these modifications relate to the products hydrophobic and latex polymer micelles. This characteristic operation is, as already said, the introduction of the initial latex which is an aqueous composition, into the solution of the hydrophobic compound or the hydrophobic compounds in a solvent or mixture of solvents miscible with water. When the initial aqueous latex is gradually introduced into the hydrophobic solute solution (in acetone, for example), the solution (acetone in the example above) gradually becomes more hydrophilic and analogous to an aqueous solution as a result of the introduction of increasing amounts of water into the solvent or mixture of solvents miscible with water. At a certain time, which depends on the nature and the quantity of the hydrophobic compounds and of the water-miscible solvent used, the hydrophobic compounds can no longer remain dissolved and begin to become insoluble. At this time, a large number of initial latex was introduced into the solutioa (acetone, for example) at the same time as the latex water. \ '"I ir-, nt, these micelles swell more or less in the presence of solvent (acetone, for example) and thus become receptive ?. .s for hydrophobic products which, at the time of their insolubilization, are preferably absorbed, by the micelles of the initial latex, for a reason that is not currently explained.

Thus, in the process according to the invention, the hydrophilic nature of a solution of at least one hydrophobic compound in a solvent miscible with water is gradually increased in the presence of micelles of charged polymer which are not dissolved to a point. where practically no hydrophobic compound remains dissolved in the water-miscible solvent. The increase in hydrophilicity is obtained by adding to the solution of the hydrophobic compound the water provided by the initial latex (of a type which can be loaded with hydrophobic compounds).

It should be noted that a certain amount of water may be present in the solution of hydrophobic compound or hydrophobic compounds in a solvent or mixture of solvents miscible with water, if desired, before the start of the operation just described, as long as the amount of this water is less than that which could act on the desired mechanism, described above and advantageously less than the amount of water which begins to cloud the solution of compound hydrophobic in water-miscible solvent.

Among the advantages resulting from the present invention, the following will be cited:

a) hydrophobic compounds such as ballasted couplers, ultraviolet radiation absorbents, light-filtering dyes, sensitizing dyes, other hydrophobic dyes, hydrophobic developing dyes, hydrophobic silver halide developers, hydrophobic dye-releasing compounds, hydrophobic optical brightening agents, hydrophobic solvents for silver halides, and the like (which may be dissolved in at least one water-soluble organic solvent, as described below) may be dispersed uniformly in a layer of hydrophilic colloid without the use of an energy-consuming grinder. Thus, by the process according to the invention, dispersions of satisfactory quality are obtained with considerably reduced expenditure and with undesirable degradation of the constituents significantly lower than by the processes requiring extensive grinding.

b) Some of the charged latex compositions have exceptional properties: for example, the particle sizes of certain dye-forming couplers are smaller in the photographic products prepared with compositions prepared themselves according to the invention than in the photographic products analogues prepared in the usual manner; the reaction between the coupler and the developer-5 then occurs under better conditions. Some of the hydrophobic parts of the charged latex act better: for example, the absorbents of the ultraviolet exhibit better absorption of these radiations when they are used according to the invention.

mc) when hydrophobic compounds very sensitive to air oxidation are dispersed according to the invention in the micelles of a latex which can be charged according to the invention, a particular resistance to oxidation is observed because the particles of these compounds are well incorporated into the micel-i .s of the polymer. Thus, the present invention provides a means for dispersing in layers of hydrophilic colloids materials which, by another industrial technique, cannot be dispersed therein in a period of time small enough to avoid excessive degradation. As examples of products sensitive to air oxidation, mention may be made of amine chromogenic organic developers such as para-phenylenedia mines, para-aminophenols, certain pesticides, etc.

d) The process according to the invention often makes it possible to disperse in the micelles much greater proportions of

25 hydrophobic compounds than what the known techniques allow.

e) In certain cases, the use of a charged latex according to the invention makes it possible to introduce a hydrophobic product into a given layer, when this is impossible otherwise, either by

M) lack of compatibility, either by excess reactivity (due, for example, to the general reactivity of the hydrophobic product with other constituents of the layer). In these situations, the application of the invention can eliminate the need to deposit several layers on a support to form a complex product comprising two constituents usually too reactive to be contained in the same layer.

Preferably, the water-miscible organic solvents which can be used in the implementation of the invention are soluble at 20 ° C. in distilled water at least at the rate of twenty volumes 40 for eighty volumes of water; their boiling point under atmospheric pressure is at least equal to -10 ° C and they do not dissolve more than 5/100, by mass, of micelles of the initial latex used, at 20 ° C. It is highly recommendable that these solvents have no chemical action on these micelles, although this is not always an imperative condition. Among these solvents, mention may be made of acetone, ethanol, methanol, isopropanol, methyl ethyl ketone, tetrahydrofuran, N-methylpyrroli-done, dimethylformamide, dimethyl sulfoxide and the mixtures of these solvents with one another. If the hydrophobic compound used is soluble in acetone, dimethylformamide or tetrahydrofuran, the choice of one of these solvents is particularly recommendable.

The initial latexes which can be used in the invention are those which meet the following conditions:

A) their micelles are compatible with the solvent or mixture of solvents miscible with water; in other words, they do not coagulate and do not precipitate when they are poured progressively, by stirring in the solution of the hydrophobic compound in the water-soluble solvent; on the other hand, these latexes must 6o be capable of containing the hydrophobic compound in the dispersed state;

b) these latexes are formed of a continuous phase and of micelles which are mainly micelles which can be loaded with the hydrophobic compound;

as and c) they satisfy the test referred to hereinafter as "usable latex test".

On the other hand, these latexes advantageously satisfy both

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conditions below (which are not mandatory), if they are intended for a photographic application:

d) compatible at 25 ° C. with aqueous gelatin solutions: it must be possible to prepare an aqueous composition containing 5/100 of gelatin and 5/100 of micelles; and e) an aqueous composition containing equal masses of gelatin and micelles gives, after casting and drying, a clear film, which shows the compatibility with gelatin.

The initial latex test is as follows. At 25 ° C., 250 ml of latex containing approximately 12/100 to 20/100, by mass, of micelles are slowly stirred in an equal volume of acetone. The addition is done regularly in one minute, shaking moderately. The stirring is stopped and the whole is left at 25 ° C for ten minutes. No coagulation or sedimentation is observed if the latex can be used in the process according to the invention.

The most advantageous latexes in the implementation of the invention are those in which the dispersed phase (the micelles) essentially consists of a polymer formed from:

(a) from approximately 75/100 to approximately 98/100, advantageously from 80/100 to 95/100 (approximately), by mass of ethylenic monoacid ester units, of formula R-CH = C (-R ' ) -C0-0-R ", R denoting a hydrogen atom or an alkyl group having from one to five carbon atoms, R 'denoting a hydrogen atom or a methyl group and R" denoting an aliphatic group having one to six carbon atoms;

(b) from approximately 2/100 to approximately 25/100, advantageously from 2/100 to 10/100 (approximately), by mass, of a hydrophilic ethylenic monomer, having a carboxylic acid or sulfonic acid group, not salified or salified with an alkali metal atom or with an ammonium group, this monomer advantageously having a molecular mass smaller than 300; and

(c) in the case of a photographic application of the loaded latex, for example, the latex usefully contains from approximately 2/1000 to approximately 100/1000, by mass, of one or more ethylenic monomers capable of tanning or crosslinking and containing a group or more groups which can be crosslinked by reaction with a tanning agent acceptable from the photographic point of view, such as an aldehyde, for example formaldehyde or succinaldehyde, or a mucohalogenated acid, a triazine chloride, a vinyl sulfone such as bis (vinyl sulfonylmethyl) ether, aziridine, etc., which makes it possible to obtain a tanned product.

It should be noted that the proportions of the monomers indicated above are those of the comonomers which are introduced into the polymerization apparatus for carrying out a conventional polymerization by free radicals. The products obtained in these reactions may have somewhat different compositions from those of the initial reaction mixtures for various reasons well known to those skilled in the art. Although latexes can be prepared which can be loaded with hydrophobic compounds from two, three, four or even more than four comonomers, those which are most generally advantageous for the implementation of the invention are those which are formed three or four comonomers, depending on the properties expected for the charged latex obtained. Generally, the latex polymers, the dispersed phase of which is formed from relatively soft micelles, are those which accept the greatest amounts of hydrophobic compounds in their micelles. On the other hand, if it is desired to finally prepare a layer containing a hydrophobic compound and having the best physical resistance properties, in particular a high abrasion resistance, it is necessary to use a charged latex formed of relatively particles. harder. As it is known to regulate the type of latex obtained by polymerization by means of free radicals, it is unnecessary to describe in detail the preparation of the initial latexes; it will be noted, however, that a recommendable means for preparing the initial latexes, to be loaded according to the invention, consists in using monomers dispersed in an aqueous medium by means of one or more surface-active agents, by initiating the reaction by free radicals. See, for example, United States of America patents 2,914,499, 3,033,833 and 3,547,899, or Canadian patent 704,778.

To prepare the initial latexes, the following combinations of comonomers are advantageously used:

comonomers (a): methyl, ethyl, propyl or butyl acrylate or methacrylate;

ethylenic comonomers (b) having a terminal sulfonic group, free or salified, for example a comonomer having one of the following formulas where the asterisk appended to an H indicates that this hydrogen atom can be replaced by an alkali metal atom, advantageously by a sodium or potassium atom, or by an ammonium group:

o ch3

II I

(1) ch2 = chc-n-c-ch2-so3h *

I I

h ch3

(2) ch2 = ch-c-0- (ch2) 2-s03h *,

II

o

(3) ch2 = ch-c-0- (ch2) 3-s03h *, II

o ch3 I

(4) ch2 = c-c-0- (ch2) 4-s03h *; II

O

ch3 I

(5) ch2 = c-c-0- (ch2) 2-s03h *, II

o ch3

I

(6) ch2 = c-c-0- (ch2) 3-s03h *, II

Oh

I

(7) ch2 = c-s03h *,

o ch3

II I

(8) ch2 = ch-c-n -c -ch2-s03h *, I I H H

ch3 h ch3 I I I

(9) ch2 = c -c-n -c -ch2-so3h *, II I o ch3

s

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fiO

(i5

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6

O

CHi

(10) CH2 = CH-C-N-C- (CH2) 3-S03H *, II

H CH3

(11)

CH = CH.

The general formulas of the hydrophilic ethylenic comonomers (b) which are particularly advantageous are the compounds having one of the formulas (A) H2C = C - (- R ') - CO-0-R2-S03M and (B) H2C = C (- R ') - C0-NH-R2-S03M, where R' denotes a methyl group or a hydrogen atom; R2 denotes an ethylene, methylene, 2-methylethylene, trimethylene or 2,2-dimethylethylene group; and M denotes an ammonium, hydrogen cation or an alkali metal cation.

(c) crosslinkable ethylenic comonomer containing an active methylene group, such as the following comonomers:

(12) N-allyl cyanoacetamide

(13) Ethyl methacryloylacetoacetate

(14) N-cyanoacethyl-N'-methacryloylhydrazine

(15) 2-acetoacetoxyethyl methacrylate

(16) N- (3-methacryloyloxypropyl) cyanoacetamide

(17) 2-Cyanoacetoxyethyl methacrylate

(18) N- (2-methacryloyloxymethyl) cyanoacetamide

(19) Alpha-acetoacetoxy ethyl methacrylate

(20) 2-acetoacetoxypropyl methacrylate

(21) 3-acetoacetoxy-2,2-dimethylpropyl methacrylate

(22) N-Methacryloyloxymethyl) acetoacetamide

(23) N-t-Butyl-N-methacryloyloxyethyl-acetoacetamide

(24) 2-acetoacetoxyethyl acrylate

(25) 2-acetoacetoxy-2-methylpropyl methacrylate as well as similar crosslinkable ethylenic comonomers. Some of these compounds are described in the patents of the United States of America 2 808 331.2 940 956.3 459 790 and 3 488 708. The expression “group capable of crosslinking” means a group capable of react with formaldehyde or other photographic tanning agent, for example a tanning agent from the vinyl sulfone family, the crosslinking reaction being manifested by an increase in the melting point of the hydrophilic colloid into which the latex is introduced. Typical groups capable of crosslinking, well known to specialists in the preparation of photographic products, are the primary amine groups and the active methylene groups.

Non-limiting examples of latex which can be loaded are latexes having solid contents of between approximately 2/100, by mass, and approximately 20/100, by mass, and formed from the following comonomers, the proportions, in hundredths by mass, indicated being relative to the comonomers introduced into the copolymerization mixture:

A. Secondary butyl acrylate

3 -Methacry loy loxy propan-1-sodium methyl-sulfonate 2-acetoxyethyl methacrylate

B. Normal butyl methacrylate 3-Sodium methacryloyloxypropane-1-methyl-1-sulfonate 2-acetoacetoxyethyl methacrylate

85

10 5

85

10 5

C. N-butyl methacrylate 70 Methacryloyloxypropane-1 -methyl I-

1-sodium sulfonate 15

Methyl methacrylate 10

s 2-acetoacetoxyethyl methacrylate 5

D. N-Butyl Acrylate 85 3 -Methacryloyloxypropane-1 -methyl-

1-sodium sulfonate 10

m 2-acetoacetoxyethyl methacrylate 5

E. N-Butyl acrylate 85 Sodium 2-Acrylamido-2-methylpropane sulfonate 10

is 2-acetoacetoxyethyl methacrylate 5

F. N-butyl methacrylate 75 Methyl methacrylate 10 2-Acrylamido-2-methylpropane sulfonate in sodium 10

2-acetoacetoxyethyl methacrylate 5

G. N-Butyl methacrylate 85 2-Acrylamido-2-methylpropane sulfonate

25 sodium 10

2-acetoacetoxyethyl methacrylate 5

H. N-butyl methacrylate 80 2-Acrylamido-2-methylpropane sulfonate sodium m 10

Acrylic acid 10

I. N-butyl methacrylate 50 Styrene 40 2-Acrylamido-2-methylpropane sodium sulfonate 10

J. N-butyl acrylate 40

4 "2-Acetoacetoxyethyl methacrylate 50 2-Sodium acrylamido-2-methylpropane sulfonate 10

K. 2-Acetoacetoxyethyl methacrylate 60

45 N-Butyl acrylate 30 Sodium 2-Acrylamido-2-methylpropane sulfonate 10

5 () L. N-butyl acrylate 50

2-acetoacetoxyethyl methacrylate 40 2-Sodium acrylamido-2-methylpropane sulfonate 10

55 Other usable initial latex polymers,

are the following:

M. N-Butyl Acrylate 80

Sodium 2-acrylamido-2-methylpropane sulfonate 20

do

N. N-Butyl Acrylate 95

Sodium 2-acryIamido-2-methylpropane sulfonate 5

o5

O. Styrene 90

Sodium 2-acrylamido-2-methylpropane sulfonate 10

7

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P.

Ethyl acrylate

85

3-methacryloyloxypropane-1-sulfonate

sodium

10

2-acetoacetoxyethyl methacrylate

5

Q.

Methyl acrylate

85

3-methacryloyloxypropane-1-sulfonate

sodium

10

2-acetoacetoxyethyl methacrylate

5

R.

N-Butyl acrylate

85

3-methacryloyloxypropane-1-sulfonate

sodium

15

S.

N-Butyl acrylate

70

3-methacryloyloxypropane-1-sulfonate

sodium

20

2-acrylamido-2-methylpropane sulfonate

sodium

10

T.

Ethyl acrylate

85

2-acrylamido-2-methylpropane sulfonate

sodium

10

2-acetoacetoxyethyl methacrylate

5

U.

N-Butyl methacrylate

50

Styrene

40

2-acrylamido-2-methylpropane sulfonate

sodium

10

V.

N-Butyl acrylate

70

Acrylamide

25

2-acetoacetoxyethyl methacrylate

5

w.

Methyl acrylate

85

2-acrylamido-2-methylIpropane sulfonate

sodium

10

2-acetoacetoxyethyl methacrylate

5

X.

N-Butyl methacrylate

85

2- (methacryloyloxy) methosulfate

ethyltrimethylammonium

10

2-acrylamido-2-methylpropane sulfonate

I

sodium

5

Y.

Ethyl acrylate

85

2- (methacryloyloxy) ethyl methosulfate

trimethylammonium

10

2-acrylamido-2-methylpropane sulfonate

sodium

5

Z.

N-Butyl acrylate

85

2- (methacryloyloxy) ethyl methosulfate

trimethylammonium

10

2-acrylamido-2-methylpropane sulfonate

sodium

5

AA.

. N-Butyl acrylate

95

sodium p-styrene sulfonate

5

BB. N-Butyl methacrylate

90

sodium p-styrene sulfonate

10

It is obvious from the above description that many combinations of comonomers can be used to prepare synthetic polymeric latexes which can be loaded by the process according to the invention. However, it should be noted that many polymerizable latexes cannot be used. For this reason, it is advisable, before considering that a given latex is usable, to examine it by means of the test already described. This test is also recommendable as a manufacturing control, since the batch preparation of these latexes does not always give products with regular properties. An advantageous process for preparing these latexes is described below, before the examples illustrating the invention.

The hydrophobic compounds which can be used in the implementation of the invention are all the hydrophobic compounds m which fulfill certain solubility conditions and which are useful, in particular when they are mixed or dispersed in a layer intended for a photographic application. , such as a layer containing at least 20/100 by mass of gelatin or other hydrophilic colloid. These hydrophobic compounds must be almost or totally insoluble in water at 25 ° C., their solubility being advantageously at most about 5/1000, by mass; they must be soluble in at least one organic solvent or a mixture of organic solvents which can be used in the implementation of the invention as defined above 2ii, this solubility must be obtained without the need to add an acid or a base and is advantageously at least about 5/100, by mass; finally they must precipitate by adding an equal volume of water to the solutions thus prepared.

The term "hydrophobic compound" relates to all compounds satisfying the above conditions. The method according to the invention can therefore be applied in many circumstances. It has been found, however, that the use of such hydrophobic compounds has unexpected utility. in Consequently, advantageous embodiments of the invention consist in preparing fine and homogeneous dispersions of these particular hydrophobic compounds in micelles of a charged latex. This concerns in particular the photographic technique; among the latexes loaded with photographic application, mention will be made of those which contain hydrophobic compounds of the following types: ballast couplers forming dyes; light filtering dyes; absorbents of ultraviolet; compounds releasing dyes developing agents; sensitizing dyes. Of course, these are hydrophobic compounds 4 ”according to the definition already given. These compounds are well known in photographic chemistry.

The photographic products advantageously prepared by the process according to the invention include, for example, the products intended for obtaining an image by transfer the 45 products to be treated by physical development, the radiographic products, the products which are developed at dry, products containing dye formers, etc. These photographic products are described, in particular, in the review Product Licensing Index, volume 92, pages 107-110 (December 1971), su as well as in British patent 923 045.

Although photography is one of the main applications of the new process, it is not the only one, the invention being usable whenever it is desired to disperse a hydro-55 phobic material in a polymeric material. Generally, ultimately, a layer of the composition obtained is prepared, deposited on a support, but this is not an obligation. For example, certain insecticides, in particular anti-moth agents, certain herbicides, certain hormones, certain vitamins and certain enzymes are hydrophobic compounds meeting the conditions for applying the new process, indicated above. It is obvious that the end use of such products does not necessarily imply their deposition on a support. An example of use is as follows. A hydrophobic compound f, such as an ultraviolet absorbent or a stabilizer, in the form of a charged latex, prepared according to the invention, is added, by simple mixing, to an aqueous dispersion, serving as a composition for coating, for example a "latex paint", the formula of which is already

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apart from this point. Other examples of use are described below; still others are obvious.

Examples of charged latexes usable in the photographic industry and indicated above are compositions formed from an initial latex, defined above, in the micelles containing, in uniform dispersion, one or more hydrophobic products, as described above. above. Generally, the quantity of hydrophobic constituent thus intimately dispersed in the micelles of the latex is between 2 or even less than 2 to 200 or even more than 200 per 100 parts, by mass, of solid polymer capable of being loaded, contained in the latex. initial. It is recommended that the proportion by mass of hydrophobic material / polymer is between approximately 1/20 and approximately 1/1.

In the photographic technique, hydrophobic compounds which the invention very advantageously relates to are hydrophobic ballasted couplers which react with the oxidation products of a chromogenic amine developer by forming a dye. As examples of such couplers, which are usually classified as ketomethylenic, pyrazolonic, phenolic and naphtholic couplers, mention will be made of those described in detail in the publications indicated in the review Product Licen-sing Index, volume 92, page 110 (December 1971 ). These couplers are, moreover, well known, photographic chemists. Ballasted couplers meeting the above solubility conditions and usable in the process according to the invention are described in the patents of the United States of America 2,423,730,

2,778,658.2 983,608, 3,252,924.3 253,924.3 277,155,

3,277,550.3 277,554.3 311,476.3 408 194.3,447,928, 3,458,315, 3,476,563 and 3,703,375.

Other hydrophobic compounds advantageously usable in the invention are the absorbents of the ultraviolet described in the review Product Licensing Index, volume 92 (1971), page 109, as well as in the patents of the United States of America 2,739,888 , 3 004 896.3 253 921, 3 468 897, 3 652 284, 3 387 671 and 3 706 700.

Other hydrophobic compounds which can be used in the invention are the hydrophobic dyes described in the review Product Licensing Index, Tome 92 (December 1971), pages 108-109, as well as in the patents of the United States of America 2,751,298, 3,486,897.3 506,443 and 3,652,284.

Dyestuff-forming hydrophobic compounds which can be used in the invention are described in Canadian patent 602,607, in United States patents 3,415,644, 3,415,645.3 415,646, 3,443,939, 3,443 940.3 443 941, 3 635 707.3 647 437 and 3 725 062, as well as Belgian patents 757 959,757 960,788 268 and 810 195.

Other hydrophobic compounds for photographic application, also usable in the invention, are the hydrophobic developers described in the review Product Licensing Index, volume 92 (1971), page 110, as well as in the patents of the United States of America 3 672 896.3 672 904, 3 679 426, 3 751 249 and 3 801 321.

It is easy to identify and distinguish the film products containing a composition layer prepared with a charged latex according to the invention, on the one hand, and similar compositions containing a simple mixture of polymer and hydrophobic compound, d 'somewhere else; in fact, in the films prepared in application of the invention, the micelles visibly retain their identity and, even after obtaining a dry layer, show, by their appearance, that they come from a latex, even when this latex is itself dispersed in a layer or in several layers of hydrophilic colloids containing other products, for example silver halides. The micelles of charged latex prepared according to the invention retain their identity even when the compositions which contain them have been deposited on a support, then dried, in the usual manner. This makes it possible to easily and surely distinguish the products produced by the process according to the invention and the similar products produced in a known manner. To establish that a composition may have been prepared by the process according to the invention, it must be shown: (a) that its particles come from a latex; and (b) the hydrophobic compound remains physically associated with these particles, or in other words, that it is dispersed in these particles, possibly in the form of a solid solution. Isolate the particles of such a composition deposited on a support, then dried, determine if they are indeed micelles of latex and if they contain a dispersed hydrophobic compound, then determine the nature of the proportion of this compound. scope of a specialist analyst chemist.

In this regard, it is particularly interesting to note that certain hydrophobic compounds can modify the polymer glass transition temperature forming the micelles of the latex; this depends on the proportions of polymer and hydrophobic compound and on their glass transition temperatures. That the introduction of a hydrophobic compound into a latex can modify its glass transition point is not surprising since this compound is finely dispersed in the micelles of the initial latex to form the dispersed phase of the composition.

Moreover, the measurement of the glass transition temperature is a means of identifying certain advantageous charged latex compositions, since, for many compositions, the variation of this temperature by introduction of the hydrophobic compound is 5 ° C. or more than 5 ° C. Certain loaded latex compositions do not exhibit this characteristic, because the glass transition temperatures of the mother poly-M forming the initial micelles and of the hydrophobic compound are too close or because the proportion of hydrophobic compound is too small. As the glass transition temperature of a homogeneous mixture is intermediate between those of the constituents, it may happen that certain charged latex compositions have glass transition temperatures which differ by less than 5 ° C. from similar non-charged latex compositions. Nevertheless, for a large number of charged latex compositions, the variation in the glass transition temperature reaches several centesimal degrees: it is then a 4 (means of identifying compositions according to the invention or as prepared by the process according to the invention.

The methods for measuring the glass transition temperature are well known. One satisfactory method consists in continuously recording the temperature of a sample in a conventional differential thermal analysis apparatus, by comparing it with the temperature of a control. The temperature corresponding to the mid-height of the jump in heat capacity accompanying the glass transformation is the glass transition temperature.

5 (The single figure in the accompanying drawing illustrates this method. Curve A is the differential thermal analysis curve, a charged polymer latex (having a natural glass transition temperature of -42 ° C) into which 40/100 has been introduced. , by mass, of a coupler forming a blue-green dye 5? (having a glass transition temperature of + 39 ° C.), using the method according to the invention. This curve A shows a glass transition temperature of the polymer loaded with approximately -15 ° C. Curve B, given for comparison, is the differential thermal analysis curve of a sample M of a composition (physically heterogeneous) and of the same latex and the same coupler as simply mixed, then dried. The endothermic zone (at about 135 ° C.) very visible on curve B corresponds to the melting point of the crystallized coupler and shows that the composition is heterogeneous. It will be noted that the charged latex compositions can generally be distinguished es in the presence of gelatin, as shown in curves A and B, the small inflections at approximately 60 ° C. The inflections at approximately 93 ° C correspond to the

9

616,440

gel-soil transition. The samples used to establish curves A and B both contain gelatin.

It seems that some of the advantageous results obtained by applying the invention come from the extremely small dimensions of the particles of hydrophobic products in the micelles of charged latex dispersed themselves in layers of hydrophilic colloids such as layers of gelatinized photographic emulsions. Thus, while the dimensions of the dispersed coupler particles, prepared by dissolution in a solvent boiling at high temperature, then dispersion in the photographic emulsion by means of a colloid mill, which is a large consumer of energy, are typically , in the usual photographic emulsions, comprised between approximately 300 nm and approximately 900 nm, and are sometimes even larger (these numerical data are relative to the diameters), the micelles of charged latex for photographic use which are prepared by the process according to are much smaller, their dimensions being between approximately 20 nm and approximately 200 nm (data relating to diameters) and, advantageously, between approximately 20 nm and approximately 80 nm, even when the latex has been swollen by the introduction of a large proportion of hydrophobic compound. For example, in one experiment, the initial average diameter of the micelles is 117 nm, but it becomes 186 nm after incorporation of a mass of blue-green coupler equal to the mass of the polymer in the latex.

The very small size of the micelles can explain at least partially that the photographic layers containing a hydrophilic colloid and a dye-forming coupler provided in the form of a charged latex according to the invention give a dye distribution much more uniform than the distribution already observed. . It seems that the particular physicochemical state of the dye-forming coupler in compositions containing a charged latex contributes, in an unexplained manner, to obtaining interesting and unexpected results. For example, photographic products containing emulsion layers which contain couplers in the form of charged latex and do not contain the usual coupler solvent (having a high boiling point) can be developed by means of a color developer. containing no organic solvent such as benzyl alcohol, while, according to the teachings of the known technique, it is necessary to introduce such a solvent into a chromogenic developer, in the absence of solvent with a high boiling point, to be able to obtain a satisfactory chromogenic development.

Another advantageous property of photographic products containing a charged latex prepared according to the invention is the reduction in the sensitivity to pressure and to mechanical actions, which certain photographic products exhibit. This problem is dealt with in the following documents: J. Soc. Phot. Japan, tome 22, n ° 3, pages 135-138 (1959); J. Phot. Sci .: volume 21, pages 32-38 (1973); J. Phot. Sci .: volume 21, pages 221-226 (1973); and Research Disclosure, volume 116, pages 135-137 (1973). This defect is reduced or even eliminated completely when the usual solutions of hydrophobic compounds are replaced by charged latexes, in order to manufacture photographic products of the type sometimes exhibiting this defect. For example, dyes which have been introduced in the form of charged latexes do not migrate as easily along the fracture lines of a photographic product subjected to pressure or stresses.

Another important property of the process according to the invention is the surprising possibility of introducing a very large quantity of hydrophobic products into an initial latex. The known techniques for preparing latexes loaded with hydrophobic materials such as plasticizers, developers or couplers soluble in basic medium, only allow quantities of these products to be introduced into the latexes much smaller than the process according to the invention. . On the other hand, the time required to introduce a hydrophobic compound into a latex is very considerably reduced by the process according to the invention compared to known techniques, such as those of the patents of the United States of America 2,772,163.3 438,920 s or 3,518,088. For example, liquid plasticizers are introduced into latex micelles by kneading these oily consistency plasticizers with the latex for several hours, according to the teachings of patent 3,438,920 precipitated, and it is not possible to thus introducing into the latex only a relatively small proportion of plasticizer; on the contrary, the process according to the invention makes it possible to introduce a mass of hydrophobic compound greater than that of the latex particles, and the operation is very rapid. The process according to the invention very advantageously makes it possible to prepare charged latex compositions containing from about twenty-five to about sixty parts by mass of hydrophobic compound, such as a dye-forming coupler, for example, per hundred parts in mass of dried charged latex. In these compositions, which are made according to a particularly advantageous mode of implementation of the process according to the invention, the hydrophobic compound is uniformly dispersed in the charged polymer, which gives a large number of properties useful to objects, such as than photographic products, produced by applying this process.

The aforementioned Tong patent describes another method for introducing a hydrophobic compound into a hydrosol of polymeric material. This process applies only to the dispersion of couplers forming dyes soluble in basic medium only, that is to say the couplers which must first be dissolved in a strongly basic medium, for example in m a hydroxide solution. sodium to be able to disperse them, to prepare photographic emulsions. In this process, the coupler is dissolved in a mixture of ethyl alcohol and water, made basic, before mixing a polymeric hydrosol with the solution obtained. The alcohol used by Tong wets the couplers and thus facilitates their dissolution in the basic aqueous solution. The latex containing the coupler and the solvent is then neutralized immediately before mixing with a photographic emulsion, during this mixing or after this mixing. Tong's invention relates only to hydrophobic couplers 4 ", but soluble in basic aqueous medium; on the other hand, it only allows the introduction of limited quantities of couplers into the latex particles. The process that Tong uses to introduce into hydrosol particles a few couplers soluble in basic medium differs greatly from the pro-45 ceded according to the invention. The polymeric latexes used by Tong are not latexes which can be loaded according to the test described above. The process according to the invention is of much more general application and makes it possible to introduce into photographic emulsions almost all of the subsequent hydrophobic additions, since practically all these hydrophobic compounds are soluble in at least one solvent miscible with water without it is necessary to add a basic reagent.

In the process according to the invention, it is very important to add the initial chargeable latex to the solution of hydrophobic compound in a water-miscible solvent. Reversing the order of addition generally results in coagulation and sedimentation of the latex or precipitation of a large part of the hydrophobic compound outside of the latex particles, so that the composition exhibits a less advantageous physical state.

In the process according to the invention, the relative proportions by volume of the initial latex and of the solution of the hydrophobic compound or of all the hydrophobic compounds in the water-miscible solvent, are generally not critical, at f'Scondition that the mixing be done in the prescribed manner. Thus, as long as the initial latex micelles are present in the solution during the time interval when the hydrophobic compound is removed (because this solution becomes progressive

616,440

10

hydrophilic, as already explained), it forms charged micelles. For example, according to a discontinuous mode of implementation, the new process comprises the following operations: (a) the introduction of an insufficient quantity of initial latex to modify the state of the solution to the point of causing separation of the compound hydrophobic; and (b) adding to the mixture obtained a quantity of water sufficient to produce the desired transfer of all the hydrophobic compounds from the water-miscible solvent into the micelles of the latex. By this technique, a latex can be prepared, the micelles of which are highly charged, while using an initial solution of relatively dilute hydrophobic compound. It can therefore be seen that various variants can be used to increase the hydrophility of the hydrophobic solution (during the period when the hydrophobic compound becomes insoluble in this solution). For this reason, when, in the general definition of the invention, one speaks of the amount of water making all the hydrophobic compounds insoluble, one must count pure water, water from latex, water supplied in the form of saline, etc.

It is generally preferable, when the solid phase of the initial latex forms more than 10/100 of the total mass, to mix one hundred parts by volume of initial latex with a number of parts by volume of hydrophobic composition of between approximately fifty and approximately two hundred ; it is preferable to use approximately equal volumes of latex and hydrophobic solution, in particular if the content of the initial latex in micelles of polymer is between approximately 12/100 and approximately 20/100, by mass. Although the optimal duration of progressive mixing of the latex and the hydrophobic compound solution may vary depending on: (a) the nature of the initial latex, the hydrophilic compounds and their solvent: (b) the concentrations of latex in micelles and of solution of hydrophobic compounds, it is generally advisable that the addition of the latex to the dissolved hydrophobic compound lasts at least about ten seconds, particularly when the content of solid polymer latex is greater than about 12/100, by mass. It has been found that mixing too quickly can produce another solid phase in the composition and / or produce coagulation and sedimension of the latex particles. Even more advisable is a gradual introduction with mixing in more than around twenty seconds.

Generally, after the preparation of a charged latex useful in photography, it is possible, without disadvantage for its use, to partially or totally eliminate the water-miscible solvent which served to prepare it. This solvent can advantageously be evaporated by any of the well-known methods used to evaporate a solvent, for example at a temperature below about 40 ° C., advantageously under reduced pressure. At least half of this solvent is thus advantageously removed. The compositions thus obtained, according to an advantageous application of the invention, retain the properties of the latexes: they are formed from an aqueous continuous phase, containing, if desired, a certain proportion of the water-miscible solvent, advantageously not more than about 30/100 by mass, and of a dispersed micellar phase formed from charged micelles, the hydrophobic compound being practically entirely dispersed in the micelles. As already explained, the organic solvent and / or a fraction of the water can, if desired, be removed from the charged latex, which gives a more concentrated charged latex. To improve the stability of the loaded latex, and reduce or prevent it from sedimenting during a long rest, it can be mixed with an aqueous solution of a hydrophilic colloid such as gelatin. It is advantageous to add at least 1/100 of hydrophilic colloid relative to the mass of latex, although much more can be added to form a stabilized latex.

If desired, a layer of stabilized latex can be deposited directly on a support, by any suitable means. So,

a large fraction of the water (generally at least half, but preferably at least 80/100) is removed from the layer (advantageously by evaporation) to form the product which is to be obtained and which is formed from a support and a layer of latex. Many other products can be present in these coating compositions, with charged micelles and hydrophilic colloid. For example, photosensitive silver halide particles, sensitizing dyes, haze inhibitors, coating aids, etc. m can be mixed with the latex compositions loaded, intended for photographic use so as to obtain layers useful for certain uses. The composition deposited must be such that the composition of the final dry layer is indeed that which is expected. Generally, in order to prepare a useful coating composition containing such additions, it is possible simply to mix dispersions and / or solutions in water of these additions, in suitable proportions, with one of the charged latex compositions, for photographic use, preferably shortly before coating the composition or the emulsion on its support.

All coating techniques including the use of a hopper and / or any other device which can be used to deposit conventional photographic emulsions on conventional photographic supports can be used to apply a layer or several layers of such compositions. lying on a support. The usable coating techniques, as well as the appropriate supports are described in the publications cited in Product Licensing Index, volume 92, page 109 (December 1971).

The process according to the invention for preparing charged latexes and the application of the compositions obtained on a support by forming a layer which contains at least one hydrophilic colloid can be carried out at all temperatures of between approximately 0 ° C. and approximately 40 ° C. or, even at more than 40 ° C; it suffices simply to pay attention to slowing down or accelerating, as the case may be, the setting in gel of the coating composition; it is generally recommended that the impregnation of the micelles with the hydrophobic compound be carried out at least at about 25 ° C.

It has been observed that, under certain circumstances, mainly if the initial polymeric latexes contain relatively hard micelles (i.e., latexes with high glass transition temperatures), the micelles more readily accept hydrophobic products. if these micelles are impregnated with hydrophobic product at a relatively high temperature, such as at about 30 ° C. or at more than 30 ° C.

Although the rest of the description does not show the use of a small number of initial latexes which can be loaded, it is clear that this is not a limitation, but only an illustration of the invention. In particular, non-cited hydrophobic compounds can be used in a manner analogous to the descriptions which follow.

By way of indication and outside the invention, a process is described which makes it possible to prepare latexes which can be loaded by the process according to the invention.

55 A solution having the following composition is prepared:

"Triton 770" (alkylaryl-polyether-sodium sulfate 1 g sold by the company Rohm & Haas Co)

Potassium peroxydisulfate 0.5 g

60 Sodium pyrosulfite 0.1 g

Water 200 ml

This solution is heated to 95 ° C. in a poly-meriser, and a mixture of 85 g of acrylate (5 secondary butyl late and 5 g is added simultaneously and gradually, over twenty minutes, with continuous stirring. 2-acetoacetoxyethyl methacrylate, a mixture of 10 g of sodium 3-methacryloyloxypropane-1-sulfonate, 0.15 g of sodium pyrosulfite and 100 ml of water at 95 ° C. Stirring is continued for

11

616,440

seventy minutes after the end of the addition, while maintaining the reagents at the temperature of 95 ° C. The latex formed is cooled, then dialyzed for approximately sixteen hours against distilled water circulating in a conventional dialyzer . The solids content of the polymer latex formed is 9.5%.

The latex thus prepared successfully undergoes the load capacity test described above. By varying the relative proportions of the various comonomers and of water, it is possible to prepare latexes having other contents in solid part.

To determine whether the latex used by Tong, as described in US Pat. No. 2,772,163, could be considered as an initial latex which can be used, the following test was carried out.

100 parts, by volume of acetone, are stirred in a container and an aqueous latex, prepared by emulsion polymerization of a mixture of 588/1000 of normal butyl acrylate, 252 /, is gradually added over about twenty seconds. 1000 of styrene and 160/1000 of methacrylamide, as in Examples 1 of the patents of the United States of America 2,772,163 and 2,739,137. The content of this latex in solids is 118%; 1000. In a few minutes, a large part of this latex has flocculated and agglomerated. This shows that the latex used by Tong is not a usable initial latex, as defined above.

The following examples illustrate the invention. ;

EXAMPLE 1

To a solution of 10 g of yellow-forming coupler, alpha-4 (4-benzyloxyphenylsulfonyl) phenoxy-alpha-pivalyl-2-chloro-5- (gamma-2,4-di-tertioamyI-phenoxybutylamido) -ac- -tanilide, in 160 ml of acetone, 90 g of initial latex are gradually added over approximately one minute, with stirring, differing from that of the preceding description in that its dry extract (or solids content) is 113 / 1000, after drying at 110 ° C.

After completion of the mixture, most of the acetone is removed by evaporation in a rotary evaporator, at 40 ° C. The charged latex does not coagulate when it is stored, after coating on a transparent photographic support it gives a transparent layer. This composition formed from latex loaded with a hydrophobic compound is also compatible with gelatin.

EXAMPLES 2 and 3 The procedure is analogous to Example 1 and practically identical results are obtained by using alpha-pivalyl-αIpha- (4-carboxyphenoxy) -2-chloro-5- as couplers; [gamma- (2,4-di-tertioamylphenoxy) butyramido] -acetanilide (as in Example 2) or 2- [aIpha- (2,4-di-tertioamyIphé-noxy) butyramido] -4,6-di -5-chloro-methylphenol (Example 3); the latter coupler is a blue-green dye former.

Use in a photographic product of the compositions of Examples 1 to 3-

Three chromogenic emulsions are prepared from appropriately spectrally sensitized silver halide photographic emulsions, as described below:

A. The charged latex prepared in Example 3 is mixed with a photographic emulsion sensitive to red, having no special characteristic, then the chromogenic emulsion thus formed is deposited on a film of polymer material,

1 forming a photographic support; after drying, a homogeneous layer is obtained which contains, per square decimetre, 8.5 mg of coupler, 3.7 mg of silver and 32.1 mg of gelatin.

B. The charged latex prepared in Example 1 is mixed with a blue-sensitive photographic emulsion. It is deposited on a photographic support, as in part A, and one obtains, after drying, a homogeneous layer which contains, per square decimetre, 7.1 mg of coupler, 3.8 mg of silver and 11.7 mg gelatin.

i C. An emulsion is prepared analogously to part B. above using the charged latex prepared in Example 2, the initial emulsion being sensitized for green.

D. Each photographic product thus prepared is exposed and developed in the usual manner to determine the relative sensitivity, the maximum density, the gamma and the minimum density. Control emulsions without charged latex are prepared, these emulsions containing the same amounts of the same couplers dissolved in usual coupler solvents. The developments are made at 24 ° C., and the results of Table I are obtained below, the precise treatment being set out below.

TABLE I

Emulsion

Sensitivity

Density

Gamma

Density

maximum relative

minimal

Prepared for Part A

257

2.84

3.16

0.05

Witness

282

2.97

3.13

0.05

Prepared for Part B

69

1.42

2.33

0.05

Witness

46

1.15

1.13

0.05

Prepared for Part C

80

1.77

3.13

0.05

Witness

76

1.67

2.93

0.05

The photographic processing is as follows:

n / a The treatment solutions are as follows:

Preliminary bath

10 s

Preliminary bath

Rinsing

10 s

Water

800 ml

Development

8 mins

Borax Na2B407.10 H20

20g

Rinsing

10 s

Sodium sulfate, anhydrous

100g

Fixing

2 mins

m Sodium hydroxide (solution

Washing

1 min

cold at 10/100)

10.0 ml

Whitening

6 mins

Water q.s.p.

1000 ml

Washing

2 mins

pH at 21 ° C

9.30 ± 0.1

616,440

12

Color developer Water (at around 21 ° C-24 ° C) Sodium hexametaphosphate Sodium sulfite, anhydrous 2-amino-5-diethylaminotoluene monohydrochloride Sodium carbonate Potassium bromide or sodium bromide Water q.s.

pH adjusted to 10.63 ± 0.05 at 21 ° C Density at 21 ° C

Fixer Water at around 50 ° C Sodium thiosulfate Sodium sulfite, anhydrous Crystallized acetic acid Crystallized boric acid Potash alum

800 ml 2.0 g 4.0 g

3.0 g 20.0 g 2.0 g

1.7g

1000 ml 1.023 ± 0.003

600 ml 240.0 g 15.0 g 13.4 ml 7.5 g

Water q.s.p.

pH at 21 ° C Density

s Whitening bath Water at around 21 ° C Potassium bromide or sodium bromide Potassium dichromate m Potash alum Water q.s.p ^

pH adjusted to 3.1 + 0.20 at 21 ° C by addition of sodium hydroxide in 10/100 solution or 7 N sulfuric acid

Density at 21 ° C 1.036 ± 0.003

E. The manipulations described under D. are repeated, except that a cobalt-hexam-mine developer-amplifier is used, according to the technique described in US Pat. No. 3,765,891. The results of table II.

1000 ml 4.25 ± 0.25 1.150 ± 0.005

800 ml 20.0 g 17.0 g 5.0 g 40.0 g 1000 ml

TABLE II

Emulsion

Sensitivity

and. ■ .ite

Gamma

Density

maximum relative

minimal

Prepared for Part A

525

3.46

4.56

0.08

Witness

562

3.56

4.43

0.11

Prepared for Part B

795

1.47

1.63

0.08

Witness

832

1.33

1.30

0.08

Prepared for Part C

1107

1.80

1.50

0.08

Witness

1123

1.74

1.90

0.08

We observe that, in the examples above, the composites 3 698 897.3 628 952 and Belgian patents 788 268,796 041,

The loaded latex according to the invention are dispersed in 796,040 and 810,195.

photographic emulsions without the use of a coarse grinder Latex charged with such compounds can consume energy and without it being necessary to pass, operating in a manner analogous to example 1, using a great deal of time to introduce couplers in emulsifiers, a water-miscible solvent, the choice of which depends on the compound

photographic sions. Nevertheless, the results presented to the specific to disperse. Generally, they are then introduced in Tables I and II show that the photographic products in a hydrophilic colloidal composition used for preparing, prepared in application of the invention have properties that are a photographic layer.

effective and comparable to those of the usual products for EXAMPLE 4

Ph0SrPmpieràe ° xœptrionnelle of these new products "This example P ^ paration of a latex charged by a

,, r .. \,,, .. ..... ,, hydrophobic compound releasing a dye by photographic oxidation-reduction should be noted: the very high reactivity of K .... ... . ,,, \,. T1

'I. , .. ,,. j j - i. and its use in the manufacture of a photographic product. It coupler with the oxidation products of the chro-,, developer. , ^,. î \ ". 6 ^ n

, | ,. . „. _ „1 i- compare the photographic product thus obtained with a pro-

mogene, during development. For some poorly explained reason, t. ■ Js „..... f f J. ■ *. he V,,. ,. ,, .., f photographic product containing the same compound releasing a quee, this reactivity is such that it is not necessary to use, ()? ... ■ c. • - ■ -

not , , . i. ,, i, u r i "" Oxidation-reduction dye, made in known manner,

a special solvent, such as benzyl alcohol or a coupler solvent, when the coupler is dispersed in the emulsion. „, ... ...,. ,

c j 1; u 'r \ j A. Preparation of a composition containing the latex filler -

form of latex filler. When using 1 invention to disper- ~ ^ r.,,,, ..., ^ °.

using couplers, as described above, we obtain a 1SS0 "® ucompose y rap o e î eran iincoo

. ■. ,, - u, rant by oxydo-reduction in 240 ml of tetrahydrofuran in tition of these in the gelatin layers much safer. ,,. ^ t, • t

..., j • tl,, „,, stirring everything at room temperature. Then, with uniform stirring only by dispersing the couplers in a known manner. By °,. Consequently, as a result of the chromogenic development, the coloration, 150 g of an initial latex are gradually added,

rants formed are dispersed in the layers which contain them, ejre ° n £ laCe all in the photographic product giving the final image Under V1J * Ç, about 99 100 of the tetrahydrofu-

much more so than in M rTjnne '° f flltf' photographic products on a paper filter (usual "Reeve Angel Grade 230" filter). The mass of the latex is adjusted to 200

The following examples relate to latexes charged with comprising a 35/100 gelatin solution, in layers liberating dyes by oxidation-reduction, which are oxidizing at 50 C. by cooling the composition from the oxidation products of the chromogenic developers of gelatin and latex filler, and it is kept cold until born. For example, these compounds can undergo fis u cross oxidation to form new bodies which release colo B. Preparation of the photographic product -

rants, for example by basic hydrolysis. This is described. We will consult, for example, French patent 2 154 443

in particular, to patents of the United States of America 3,725,062, for details on the structures of the various layers

13

616,440

of this product, the general structure of which is as follows:

(a) transparent sheet forming a cover

(b) surface layer of gelatin

(c) red sensitive emulsion

(d) composition containing the hydrophobic compound releasing a dye by redox

(e) carbon + gelatin

(f) titanium dioxide + gelatin

(g) bite + gelatin

(h) transparent support in poly (ethylene terephthalate)

The layer of composition (d) is prepared with a charged latex composition, prepared according to part A, of the present example, the hydrophobic compound releasing a dye by redox being N- [4-2,4-di-tertiopentyIphenoxy ) bu-tyl] -l-hydroxy-4- {3- [5-hydroxy-6- (2-methylsulfonyl-4-nitro-phenylazo) -l-naphthylsulfanoyl] benzenesu Ifonamido} -2-naph-tamide, the initial latex being a terpolymer latex of 85 parts of normal butyl acrylate, 10 parts of 3-metha-crylolyoxypropane-1-sulfonate and 5 parts of 2-acetoacetoxyethyl methacrylate. The coated composition is such that the dry layer contains, per square decimetre, 0.54 g of hydrophobic compound, 0.54 g of latex copolymer and 1.08 g of gelatin.

C. Preparation of a control photographic product -

A photographic product which differs from the preceding one is prepared only by the composition of layer (d), which is a dispersion in gelatin of the same hydrophobic compound dissolved in a solvent, the bis (2-ethylhexanoate) of 1,4-cyclo hexylenedimethylene. The layer contains the same amounts of gelatin and hydrophobic compound as the layer of the product prepared in B.; it contains 0.27 g of solvent per square meter.

m D. Comparative tests-

The two photographic products prepared in B. and in C. are exposed for 1/100 of a second, through the light of a tungsten lamp through a rung corner filtering red light, then a viscous composition of 15 is spread. treatment, basic and containing carbon, from a frangible capsule, between the transparent sheet and the photosensitive product, at around 22 ° C., passing everything between superimposed rollers, so that the composition layer has a 0.127 mm thick. By development, 2 (i forms a blue-green image in the layer (g) containing the mordant, by transfer by diffusion. The sensitometric results are as follows:

Sensitivity Contrast Density Minimum relative relative density (gamma)

Product C. (invention) Product D. (witness)

110 100

1.59 1.42

0.20 0.22

Relative sensitivity is measured for a density equal to the minimum density increased by 1.0.

The sensitometric results are almost identical,

EXAMPLE 5

The hydrophobic compounds exhibit unexpected properties when they are dispersed in layers using the process according to the invention, in addition to the properties which result from a more regular dispersion. This is highlighted by this example relating to an absorbent of the ultraviolet.

There is an abnormally large optical density and an abnormally precise limit of the spectral absorption zone.

A. A latex composition charged with a hydrophobic absorbent of the ultraviolet is prepared by first dissolving 40 g of 3-dihexylaminoallylidenemalonitrile, which is liquid at ordinary temperature, in 400 ml of acetone, then gradually pouring into this solution , with stirring, 1320 g of a latex containing 95/1000 of solid material; this latex is an aqueous suspension of micelles of metha terpolymer

1.91

1.96

normal butyl crylate, 2-acrylamido-2-methylpropanesulfonic acid and 2-acetoacetoxyethyl methacrylate (85/10/5). The acetone is then removed by heating at 50 ° C., under vacuum, for approximately 24 mm. The latex thus loaded is mixed with an aqueous gelatin solution; a layer of the composition thus formed is deposited on a transparent photographic support, and this layer is dried.

B. By way of comparison, the same absorbent is dispersed in gelatin by means of a colloid mill, and a layer of the composition thus formed is deposited on a similar support, the amounts of gelatin and absorbent of 1 'ultraviolet deposited being the same in both cases.

C. By way of comparison, the same liquid absorbent is dissolved in its volume of a solvent having a high point, normal dibutyl phthalate, then the solution is dispersed in an aqueous gelatin solution by means of a colloid mill, the usual way. A layer of composition having the same amounts of gelatin and absorbent as the previous ones (after drying) is deposited on a support identical to the previous ones. The following results are obtained:

TABLE III

Layer compositions Optical densities in g / m2

Absorbent gelatin

at 370 nm

at 415 nm

Control test

0.54

0

0.08

0.05

Solvent and

latex

0.54

0.20

1.16

0.55

Latex-free solvent

0.54

0.20

1.60

0.42

Solvent-free latex

0.54

0.20

3.00

0.11

EXAMPLE 6

These unexpected results show that the compositions of this example describe the preparation of a photographic product.

charged latex absorb much more ultraviolet and that the limit that containing a filter dye introduced by the following absorption process is much sharper. the invention.

616,440

14

Three products are prepared for color photography, comprising a yellow filtering layer between the blue-sensitive layer and the green-sensitive layer. Apart from this filtering layer, these three products are identical and contain the usual layers described in British patent 923 0 45 and in United States patent 3,046,129. The filtering layers are dispersions in gelatin and contain 980 mg gelatin per square meter.

The first product contains colloidal silver (the so-called “Carey-Lea” layer), at a rate of 54 mg per square meter. The second product contains an etched dye, i.e., per square meter, 74 mg of 4 - [(3-ethyl-2-benzoxazolylidene) -ethyli-dene] -3-methyl-l- (p.sulfophenyl-2-pyrazolin -5-one etched with 86 mg of poly (alpha-methylallyl-N-guanidyl ketimine), as described in US Patent 3,282,699. These two products are prepared for comparison, outside the invention .

The third product, prepared in application of the invention, contains, per square meter, 260 mg of the latex, the preparation of which has

TABLE IV Filter layer

Carey-Lea layer 100 428

Etched dye 73 448

Loaded latex 82 450

These results show that latex compositions loaded with a light-filtering dye can advantageously replace Carey-Lea colloidal silver as a filter for blue light, in products for color photography. It will be noted that the desensitization of the blue-sensitive layer by such a composition is much less than with an etched dye.

EXAMPLE 7

This example relates to the use of a latex loaded with a sensitizing dye in the preparation of a photographic product which is developed by means of vapor of basic compound.

A. Preparation of a comparison product -

On a polyethylene terephthalate support, a layer of photosensitive composition comprising the following ingredients is deposited, at a rate of 27.98 mg of silver and 96.84 mg of gelatin per square decimetre:

a) a conventional photographic emulsion with silver bromide, sensitized to sulfur and gold and also sensitized by reduction;

b) a spectral sensitizing dye, anhydro-3,9-die-thyl-5,5-dimethoxy-3 ', 3- (3-sulfopropyl) thiacarbocyanine, in solution in methanol;

c) ascorbic acid;

d) a haze inhibitor, 4-hydroxy-6-methyl-1,3,3a, 7-tetraazaindene;

e) an image stabilizer precursor, 3-s-thiouronium 1-methylpropa-nesulfonate;

f) an incorporated developer, 1,2,3,4-tetrahydro-1,4-methanonaphthalene-5,8-diol;

and g) a tanning agent, bis (vinylsulfonylmethyl) ether.

B. Preparation of a photographic product in application of the invention.

The following ingredients are used:

a) 350 mg of the spectral sensitizing dye used above in A .;

described above, this latex having been loaded as follows with p.diethylamino-2- (4-hexenesulfonyl-aminobenzoyl) cinna-monitrile, so that the photographic product finally contains 86 mg of this dye per square meter. The coated composition is prepared as follows: (a) 9.5 g of latex containing 152/1000 of solid constituent are diluted with 55 ml of water; (b) gradually, over one minute, this latex, diluted in a solution of 0.48 g of dye in 50 ml of tetrahydrofuran, is poured with stirring; (c) this solvent is removed in a rotary evaporator at 40 ° C; and (d) mixing the loaded latex with 267 ml of 25/1000 aqueous gelatin solution and 5.3 ml of a 15/100 aqueous saponin solution.

The three photographic products are exposed for 0.01 s to the light of a 500 W tungsten lamp, having a color temperature of 3200 ° K, in order to determine their relative sensitivities in blue, and then they are developed. normally by inversion, as described in US Patent 3,046,149. The following results are obtained:

b) 350 ml of methyl alcohol;

m c) 17 ml of water;

d) 175 ml of initial latex, prepared as described above, containing 103/1000 of solid material; and e) 17.5 ml of a 10% gelatin solution in water.

We start by gradually pouring d) into a

35 solution of a) in the mixture of b) and c), then add e), still with stirring, and a stabilized charged latex is obtained. Almost all of the methyl alcohol is eliminated by evaporation under vacuum in a rotary laboratory evaporator, then the composition is introduced into a photographic emulsion 4i) identical to that of part A. of this example, apart from the spectral sensitizing dye.

C. The compositions prepared in A. and B. are coated on polyester supports, and dried. The photographic products thus prepared are exposed for thirty seconds to the light of a 500 W tungsten lamp having a color temperature of 3000 ° K. They are exposed for thirty seconds to methylamine vapors, then washed for five minutes with distilled water. The sensitometric properties are as follows:

Control product Product prepared 55 according to the invention

These results show that, surprisingly, the charged latex compositions according to the invention, in which M the filler is a sensitizing dye, are perfectly usable in photographic products instead of alcoholic solutions of the same dyes, the charged latex composition being an effective means for dispersing such a dye in a photographic emulsion. This process is advantageous because it eliminates the alcohol before introducing the sensitizing dye into the photographic emulsion. This advantage is more important with certain dyes than with others: this depends on the relative solubilities of the dyes in alcohol.

Relative sensitivity Wavelength (in nm)

in the blue of the maximum

Sensitivity

relative

100

100

Contrast

(gamma)

6.80

6.47

Density

minimal

0.06

0.06

15

616,440

EXAMPLE 8

This example relates to the preparation of pesticide compositions.

A. "Methyl-parathion" -

15 g of commercial methylparathion (20/100 of methylparathion and 80/100 of xylene) are dissolved in 150 ml of acetone. At room temperature, 200 g of a dilute latex which has been prepared by diluting 66 g of a polymer latex which can be loaded containing 1825/10000 of solid material with sufficient water are gradually poured in with stirring. form 200 g of diluted latex. The initial latex was prepared by polymerizing a mixture of fifty parts (by weight) of normal butyl methacrylate, forty parts of styrene and ten parts of 2-acrylamido-2-methylpropanesulfonic acid, according to the technique already described.

The mixture is placed in a 200 ml container, then vacuum is carried out for fifteen minutes, at approximately 50 ° C. to remove the acetone. The composition is filtered, although no residue is observed, and a homogeneous dispersion is obtained, which does not sediment spontaneously after a large number of weeks of storage at room temperature. The micelles of the loaded latex contain the pesticide and the polymer in a mass proportion equal to approximately 1: 1.

B. "Parathion" -

The procedure is analogous to description A. above, using the following ingredients:

Parathion Acetone

18/100 solid latex Water (for latex)

7.1g 150ml 45g 108ml

In this example, 2,5-diphenyloxazole and 2,2'-paraphenylenebis (5-phenyloxazole) are combined, which are two hydrophobic scintillators.

3 g of diphenyloxazole and 0.015 g of phenylene-, bis (phenyloxazole) are dissolved in 90 ml of tetrahydrofuran, then 90 g of a dilute latex containing 9 g of normal butyl methacrylate terpolymer of styrene is slowly added to this solution and acrylamido-2-methylpropanesulfonic acid (50/40/10). The solvent is then removed in a conventional rotary evaporator. i After filtration, 25 g of a 10/100 gelatin solution are added to the charged latex composition. The composition finally stabilized by taking in gel contains 3/100 of diphenyloxazole and 15/100 000 of phenylenebis (phenyloxazole), 9/100 of polymer and 25/1000 of gelatin.

This composition is deposited on a conventional photographic support, made of poly (ethylene terephthate) covered with a sub-stratum, at a rate of 10 ml per 100 cm 2, then it is dried. Strips 51 mm by 12.7 mm are cut and treated with (a) 0.01 ml of aqueous solution of labeled benzoic acid (3H); i (b) 0.01 ml of labeled benzoic acid (3H) in solution in 1,4-dioxane; and (c) 0.01 ml of labeled benzoic acid (14C) in aqueous solution; each solution is equivalent to approximately 22,000 disintegrations per minute. The strips are dried; they are mounted in 20 ml flasks for counting, and they are counted at 12 ° C. using a “Packard Tri-Carb, Model 3380” liquid scintillator counter. The strips are normally arranged at the axes of the photomultipliers. The counting efficiency is determined by comparing the emission detected with the theoretical number of disintegrations during a determined period. The results are as follows:

In the latex loaded with pesticide thus prepared, the proportion by weight of polymer / pesticide is approximately 8: 7. The loaded latex contains 55/1000 parathion (by mass). This composition can easily be diluted with water to apply it by spraying onto the cultures, in a known manner.

EXAMPLE 9

This example relates to the preparation of a latex loaded with hydrophobic scintillating compounds, which, in combination, are used for scintillation counting. This technique is useful for detecting and measuring relatively low radioactivity and finds an application in the search for traces of radioactivity.

Sample Product measured

(at)

(b)

(vs)

Benzoic acid (3H) in water Benzoic acid (3H) in dioxane Benzoic acid (14C) in water

Counting efficiency

31.8%

25.6%

89.5%

These counting efficiencies are abnormally high for solid scintillators. This is attributed to the regularity of the dispersion of scintillating agents in the latex loaded according to the invention.

1 sheet of drawings

Claims (13)

616,440 2 1. Method for preparing a latex composition of charged polymer having a dispersed phase which essentially consists of micelles of a latex loaded with at least one hydrophobic compound dispersed in this polymer, characterized in that one gradually introduces into a solution hydrophobic compound in at least one organic solvent miscible with water, an initial latex which can be charged and an amount of water at least sufficient for the hydrophobic compound to become insoluble in the solution, this amount of water being supplied by the initial latex, or by this one and an addition of water. 2. Method according to claim 1, in which all of the water is supplied by the initial latex. 3. The method of claim 1, wherein the total time of addition of the latex is at least about ten seconds. 4. The method of claim 1, wherein at least half of the organic solvent is separated from the composition obtained by adding the initial latex to the solution of the hydrophobic compound. 5. Method according to claim 1, in which the micellar phase of the initial latex is essentially formed of a copolymer compatible with gelatin and containing units of at least two ethylenic comonomers, 2/100 to 25/100, in mass of this copolymer being formed of units of a comonomer containing free or salified sulfonic acid groups. 6. The method of claim 1, wherein the micellar phase of the initial latex is essentially formed of a copolymer comprising the following units (mass proportions): (a) from 75/100 to 98/100 of ester of monomer formula R-CH = (- R ') - CO-OR' 'where R denotes a hydrogen atom or a lower alkyl group, R' denotes a hydrogen atom or a methyl group and R "denotes an aliphatic group having one to six carbon atoms; (b) from 2/100 to 25/100, of a hydrophilic ethylenic comonomer containing a carboxylic or sulfonic group and having a molecular mass at most equal to 300. 7. The method of claim 6, wherein the copolymer comprises the following units (mass proportions): from 80/100 to 95/100 of the comonomer (a); from 2/100 to 10/100 of the comonomer (b); and from 2/1000 to 100/1000 of an ethylenic comonomer (c) and having at least one crosslinkable group. 8. The method of claim 7, wherein the comonomer (a) is methyl, ethyl, propyl or butyl acrylate or methacrylate; comonomer (b) has a terminal sulfonyl group; and the comonomer (c) comprises an active methylene group. 9. The method of claim 1, wherein the water-miscible solvent is acetone, ethyl, methyl or isopropyl alcohol, methyl ethyl ketone, tetrahydrofuran, dimethylformamide, N-methylpyrrolidone, dimethyl sulfoxide or a mixture between these solvents. 10. A charged latex composition prepared by the process according to claim 1, characterized in that the latex micelles are formed from a synthetic polymer on the surface of which and / or in the mass of which is dispersed at least one hydrophobic compound, the mass ratio of hydrophobic compound / polymer being between 1/4 and 3/1 and the average diameter of the charged micelles being between 20 nm and 200 nm. 11. The composition according to claim 10, in which the hydrophobic compound is a photographic developer, a dye-forming coupler, a redox dye-forming agent, a dye that filters visible light, a photographic sensitizing dye, an absorbent of ultraviolet or a mixture of these compounds. 12. Use of a composition obtained in accordance with the process according to claim 1, and from which the organic solvent has been removed, said composition containing an amount of hydrophobic compound thus dispersed of at least 2/100 of the mass of the dispersed phase, to form a solid layer by depositing the composition on a support and drying it. 13. Use according to claim 12, characterized in that the layer formed from said charged polymer latex composition is a layer of a photographic product containing a silver halide.