NL7909239A - ORGANIC PIGMENTS BASED ON ENT COPOLYMERS PARTICLES, AND METHOD FOR PREPARING THE SAME - Google Patents

Description

• i - -1-1 21083 / Vk / jl

Applicant: Hereules Incorporated, Wilmington, Delaware, United States of America.

Short designation: Organic pigments based on enteopolymer particles, and method for preparing them.

The invention relates to graft copolymer particles consisting essentially of a free radical-catalyzed graft copolymerization product (which graft copolymer particles are water-insoluble) of 1) at least one ethylene-unsaturated monomer and 2) a water-soluble cationic prepolymer with a RSV-10 value of about 0.1-2.5 (1 MNaCl, 1%, 25 ° C). In particular, the invention relates to new organic pigments which are particularly suitable for use as a paper filler. The organic pigments are finely divided particles obtained by graft copolymerization of an ethylene-like unsaturated monomer.

15 Paper is often filled with mineral fillers, such as clay * calcium carbonate or titanium dioxide. The function of a mineral filler is to improve opacity of the paper and to prevent translucency. Low opacity results in page-to-page translucency in printed paper such as books, weeklies and newspapers. Although the mineral fillers fulfill this function well, at a relatively low cost, they also have certain drawbacks. First, the paper strength is significantly reduced. This may present problems in later use, but more importantly, low strength may require the paper machine to operate at a slower speed. The second drawback is that the mineral additives have a relatively high density (specific gravity 2.5-4.0) and thus the weight of the filled paper is increased. This is all the more a problem with the shipping costs of printed material such as weekly magazines, because there is also an increasing demand for paper with a low weight.

Thus, there is a high demand in the paper industry for low specific weight paper opaque agents which do not adversely affect the strength of the paper.

The use of the latex particles as a low-weight filler is known to be used with paper. Polystyrene latex is commercially available for this purpose. As well as mineral fillers of these polystyrene latexes from anionic particles that require ionic retention agents to allow good retention on the anionic pulp fibers. In addition, the polystyrene latex fillers decrease the strength of the filled paper 7909239 -2-21083 / Vk / .il 1, although this occurs to a lesser extent than with the mineral fillers.

Small particles of urea-formaldehyde resin have also been used as a paper filler. These particles are known to have a low weight and when used as a filler for paper they improve opacity as well as the clarity, smoothness and pulp density of the paper. However, these materials adversely affect the paper strength, although this influence appears to be less than that of the mineral fillers. * US Pat. No. 3,834,114 discloses microcapsules with a solid polymer shell and a solid, non-tacky polymer core grafted on the polymeric scale. The microcapsules can be coated on the cellulosic substrate or incorporated into such substrates and then fused to provide cellulosic substrates with a polymeric film attached thereto and thereby increasing strength. Furthermore, it is stated in this patent that the polymer-containing microcapsules can be formed with an average particle diameter between about 0.5 to about 0.5 µm. It has been reported that the particles can impart high opacity to the surface coating of various substrates. It has also been reported that the microcapsules can be formed on the dispersion with the cellulose fibers and formed into a fabric of such fibers, and that the polymeric microcapsules act as abrasives, opacifiers, and high opacities for the cellulose substrate that is ultimately formed. .

One of the objects of the invention is to obtain organic pigments which can be used as light paper fillers and which can provide opacity, clarity and softness without adversely affecting the paper strength. Another object according to the invention is to obtain organic pigments that are retained during the processing of the paper. This can be accomplished with organic pigments that are well retained on the pulp fibers without the use of conventional retention agents.

All this may be accomplished by the use of the invention to obtain graft copolymer particles which are suitable as organic pigments, particularly as a paper filler, and which consist essentially of free-radical catalyzed graft copolymerization 7909239 m -3-21083 / Vk / µl to give a product consisting of 1) at least one ethylene-unsaturated monomer and 2) a water-soluble cationic prepolymer with an RSV value of about 0.1 to about 2.5 (1 M NaCl, 1 lb), 25 ° C), characterized in that the prepolymer unit of the graft copolymer particles are present on the surface of the particles, the monomer 1) being selected from the group consisting of methyl-chloro-acrylate, ethyl-chloro-acrylate, methyl methacrylate, isopropyl methacrylate, phenyl methacrylate, vinyl chloride, acrylonitrile, methcarylonitrile and monomers of the formula 7, indicated on the formula sheet, where R is hydrogen or a methylgr ep, Y is methyl or chlorine and n has the value of 0, 1, 2 or 3, and the prepolymer 2) the addition polymerization product is from a) about 5 mol% to about 100 mol% of at least one cationic monomer selected from the group consisting of a compound of formula 1, indicated on the formula sheet, wherein R ^ is hydrogen or methyl, R ^ is hydrogen or an alkyl group of 1-4 carbon atoms, R ^ is hydrogen, an alkyl group of 1-4 carbon atoms, -CH ^ 1jbHCHgY where Y is a hydroxyl group or a halogen atom, -CH ^ CHCHg and - (CH 2 CH 2 O) nH 20 where n is an integer with the value of 1 or more and X "is an anion, a compound of formula 2, indicated on the formula sheet, wherein R} is hydrogen or an alkyl group of 1-4 carbon atoms, R 2 is hydrogen, alkyl, substituted alkyl and R 4 and X- have the same meaning as indicated in formula 1, a compound of formula 3 , indicated on the formula sheet, where R ^, R2, R ^ and X "have the same meaning as indicated in formula 1, compounds of formula 4, indicated on the formula sheet, where R ^, R ^ and X "have the same meaning as indicated for formula 1, compounds of formula 5, are indicated on the formula sheet, wherein R ^, R2 , R ^ and X ~ have the same meaning as indicated for formula 1 and n is an integer with the value 1, 2 or 3 and compounds of formula 6, indicated on the formula sheet, where R ^, R ^ .R ^ and X “have the same meaning as indicated in formula 1 and b) about 95 mol% to 0 mol% of at least one ethylene-like unsaturated non-ionic monomer, from the group consisting of 7909239

* I

-4-2 21083 / vk / jl h '% N-vinyl pyrolidone, ethylene-like unsaturated raonomers having an amide function and ethylene-like unsaturated monomers having a hydroxyl function, the amount of prepolymer 2) being used in preparing the graft -opolymer particles is between 1 wt. parts 5 to about 25 wt. parts on every 100 wt. parts of monomer 1) that has been used.

Virtually all cationic prepolymer units of the graft copolymer particles are present on the surface of the obtained particles.

When the graft copolymer particles of the invention are suspended in water in the presence of cellulosic pulp fibers, they adhere to the anionic sites on the surface of the fibers and adhere to the pulp fibers. While preparing the paper, consisting of draining water from a slurry of the. pulp fibers are thus well retained in the paper.

Graft copolymer particles prepared using water-soluble prepolymers with an optimal content of cationic functional groups become self-retaining during paper preparation. This means that when these slurry particles are applied with the pulp fibers before layer formation takes place, the particles adhere strongly to the anionic pulp fibers and are lost very little or not when the water is filtered off during the preparation of the paper. Therefore, no retention agent is required to hold the particles together with the pulp fibers. Known means of preservation, however, can be used to prepare the paper when desired. Furthermore, the paper filled with the ente-polymer particles prepared according to the invention has strength properties that are usually equivalent and sometimes better than unfilled paper of the same weight. Papers filled with mineral pigments such as clay or titanium dioxide have considerably lower strength properties than the corresponding unfilled paper.

The monomers used to prepare the particles are such that they undergo graft polymerization on the cationic water-soluble prepolymer to form a water-insoluble graft copolymer. It is the insolubility of the graft copolymer that results in the formation of certain substantially spherical particles suspended in water.

The initial function of the water-soluble cationic prepolymers is to stabilize the suspension and to coagulate the individual 7909239 -5-21033 / Vk / jl

* I

avoid particles. After the initial graft copolymerization is accomplished, some ihomo polymerization of the monomer is possible within the particles. Substantially stable latexes of the graft copolymer particles are prepared according to the invention, without the presence of an additional stabilizer being required. There are two main requirements to prepare the graft copolymer in particulate form of the invention. These are that 1) they are insoluble in water and 2) have a sufficiently high melting point or softening point that they are not deformed to a certain extent under the heat or pressure conditions or both, to which they are further processed. will be subjected. The use of paper fillers requires that the particles maintain their particle shape and be substantially spherical during tissue formation, drying and calendering. Preferably, the ente copolymer has a second order transition temperature (glass transition temperature, Tg) of about 75 ° C or higher. All graft copolymers prepared according to the examples have a Tg value greater than 75 ° C.

All monomers leading to graft copolymers with the water-soluble cationic prepolymers described below give graft copolymer particles meeting the above requirements. Suitable monomers are monoethylene-like unsaturated monomers, such as, for example, acrylic acid esters, in particular methyl - * - chloroacrylate and ethyl - chloroacrylate, methacrylic esters such as methyl methacrylate, isopropyl methacrylate and phenyl methacrylate monomers of the formula sheet, where R is hydrogen or methyl group, Y is methyl 25 or chlorine and n has the value 0, 1, 2 or 3. Examples of such monomers are styrene, CV-methylstyrene, monochlorostyrene, dichlorostyrene, trichlorostyrene, monoraethylstyrene, dimethylstyrene and trimethylstyrene. Other suitable monomers are vinyl chloride, acrylonitrile and methacrylonitrile.

A mixture of two or more monoethylene-like unsaturated monomers can be used in the practice of the invention provided that the particulate ente polymer obtained is insoluble in water and has a Tg value of about 75 ° C or higher. Polyethylene-unsaturated monomers such as divinylbenzene can also be used in admixture with monoethylene-unsaturated monomers to obtain cross-linked graft copolymer particles. Of the above monoethylene-like unsaturated monomers, it is preferable to use styrene, vinyl chloride, acrylonitrile and methyl methacrylate.

7909239 ^ ** -6- 21083 / Vk / jl

The water-soluble cationic prepolymers can be one of the above-mentioned polymers. The main criterion is that an optimal cationic charge is present to effect good retention of the obtained ento polymer in particulate form in; the paper.

For example, in a latex prepared using about 10% prepolymer based on the weight of the monomer used, the opacity is highest when the mole percent cationic monomer unit of the water-soluble prepolymer is about 5 to 50, with an optimum range ranging from about 10 to about 30 mol%. These limits, of course, depend on the content of water-soluble cationic prepolymer used to prepare the latex. Thus, when using about 5% water-soluble prepolymer based on the monomer used, the range would be between about 10 and about 100 mole percent cationic monomer unit with an optimal range at about 20 to 60 mole percent. Similar corrections can also be made when other levels of water-soluble polymer are used and these ranges can be determined by one skilled in the art.

The cationic water-soluble prepolymers particularly suitable for use in the present invention are addition-type polymers prepared from ethylene-unsaturated cationic monomers of formulas 1, 2, 3, 4, 5, and 6 as below is indicated.

The compound of formula 1, indicated on the formula sheet, is one of the examples, wherein hydrogen is a methyl group, R 1 is hydrogen or an alkyl group having 1 to 4 carbon atoms, such as methyl, ethyl, propel or butyl, R 1 is hydrogen, an alkyl group with 1-4 carbon atoms,

OH. I

-CHjCH-SQgY where Y is a hydroxyl group or a halogen atom such as chlorine or bromine, -CHgCHCHg and (CH ^ CH ^ Ö) ^ where n is an integer of 1 or more, preferably 1-20 and X ” represents an anion such as Cl ", Br", CH 3 SO 3 "and Cff C00".

Monomers of formula 1 are quaternary ammonium salts and acidic. salts of amino acrylates such as dimethylaminoethyl acrylate, diethyl aminoacrylate, dimethylaminoethyl methacrylate and diethylaminoethyl methacrylate. Specific quaternary salt monomers of formula 1 are methacryloyloxyethyl trimethyl ammonium methyl sulfate and methacryloyloxyethyl tri-7909239-7 21083 / Vk / µl methyl ammonium chloride. Specific acidic salt monomes of formula 1 are methacryloyloxyethyldimethylammonium chloride and methacryloyloxyethyldimethyl ammonium acetate.

Compounds of formula 2, indicated on the formula sheet, are compounds wherein R 1 is hydrogen or an alkyl group of 1-4 carbon atoms. can be a hydrogen atom or an alkyl group or substituted alkyl group. Specific alkyl groups for R2 are alkyl groups of 1-18 carbon atoms, preferably of 1-6 carbon atoms, and include methyl, ethyl, propyl, isopropyl, t-butyl, hexyl, octyl, decyl, dodecyl, tetradecyl and octadecyl. R2 can also be a substituted alkyl group with suitable substituents, which are substituents that do not interact in the polymerization via a vinyl double bond. Examples of the substituents are carboxylate, cyano, ether, amine (primary, secondary or tertiary), amide, hydrazide and hydroxyl. and 15 X ”may have the meaning as defined in formula 1. The monomers of formula II are quaternary ammonium salts and acid salts of a diallylamide of formula 8, indicated on the formula sheet, where R.j and Rg have the same meanings as indicated above. Specific examples of quaternary ammonium salt monomers, of formula 2, are dimethyldiallylammonium chloride and dimethyldiallylammonium bromide. Specific examples of the acidic salt monomer of formula 2 are methyl diallyl ammonium acetate, diallyl ammonium chloride, N-methyl diallyl ammonium bromide, 2,2-dimethyl-N-methyl diallyl ammonium chloride, N-ethyl diallyl ammonium bromide, N-isoplyl ammonium bromide, Nn-25 butyl butyldiallylammonium chloride, Nn -hexyldiallylammonium chloride, N-octadecyldiallylammonium chloride, N-acetamidodiallylammoniuracl chloride, N-cyanoraethyldiallylammonium chloride, N-β-propionamidodiallylaramonium bromide, M-acetic acid ethyl ester-substituted diallyl ammonium ethyl diallyl ammonium broride and N-acetohydrazide substituted diallyl ammonium chloride.

Other examples are compounds of formula 3, indicated on the formula sheet, wherein R 1, R 5, R 3, and X - have the same meaning as indicated in formula 1. Specific examples of monomers of formula 3 are vinyl benzyl trimethyl ammonium chloride and vinyl -benzyl trimethyl ammonium bromide.

Compounds of formula 4, indicated on the formula sheet, are 7909239 -8-21083 / Vk / jl «η * c other examples where R ^, R ^ and X" have the same meaning as indicated in formula 1. Specific examples of monomers with formula 4 are 2-vinylpyridinium bromide and 2-vinylpyridinium bromide.

Compounds of formula 5, indicated on the formula sheet, can be used, where R 1, R 2, R 1 and X "have the same meaning as indicated in formula 1 and n is an integer with the values 1, 2 or 3 A specific example of such a monomer of formula 5 is methacrylamidopropyldimethylammonium chloride.

Compounds of formula 6, indicated on the formula sheet, are also examples that can be used, wherein in formula 6 Rj, Rg, Rg and X "have the same meaning as indicated in formula 1. A specific example of such a monomer of formula 6, is 3-methacryloyloxy-2-hydroxypropyl-direthylammonium chloride.

The water-soluble cationic prepolymer used according to the invention may also be a naturally occurring copolymer such as casein or a derivative of a naturally occurring polymer such as chitosan.

As mentioned above, an optimal content of cationic charge on the polymer particle is required for good fecency in the paper. The optimal charge can be obtained with a cationic homopolymer by varying the amount of homopolymer used to prepare the graft copolymer latex. However, it is preferable to adjust the cationic charge using a copolymer of at least one cationic monomer and at least one nonionic unsaturated monomer capable of addition polymerization. Examples of non-ionic monomers are monoethylene-like unsaturated amide monomers, such as acrylamide, methacrylamide, N-acetamidoacryl amide, N-acetamidomethacrylamide, N-methylolacrylamide, diacetonacryl-amide, diacetone methacrylamide, Ν, Ν-dimethyl-amethylacrylamide the. Other suitable nonionic monomers are vinyl acetate, 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate and N-vinyl pyrolidone. Copolymers of vinyl acetate are then hydrolyzed to replace almost all acetate groups with hydroxyl groups.

The water-soluble cationic prepolymers used according to the invention may be a) homopolymers of the cationic monomers as stated in formulas 1-6, b) copolymers of two or more of the monomers represented 7909239 *> * -9 21083 / Vk / jven are represented by formula 1-6 and c) phenol eopolymers of at least one of the monomeres in formulas 1-6 and at least one other ethylenically unsaturated monomer, preferably a non-ionic monomer.

Thus, the preferred water-soluble cationic prepolymers will consist essentially of about 5 mol% to 100 mol% of at least 1 monomer represented in formulas 1-6 and from 95 mol% to 0 mol% of at least another ethylene-like unsaturated non-ionic monomer.

The good water-soluble cationic prepolymers which can be used to obtain the graft copolymer particles. according to the invention 1) the prepolymers prepared from about 70 mol% to about 98 mol Jt, preferably 82 mol% to about 90 mol% acrylamide 15 and about 30 mol% to about 2 mol%, preferably 18 mol% up to 10 mol% dimethyldiallylammonium chloride, 2) the prepolymers prepared from about 67 mol% to about 98 mol, preferably about 67 mol% to about 89 mol%, acrylamide and from 33 mol% to about 2 mol%, preferably 33 mol% 20 to about 11 mole% methyldiallylammoniurachloride, 3) the prepolymers prepared from about 70 mole% to about 98 mole%, preferably about 82 mole% to about 91 mole% acrylamide, and from about 30 mole% to about 2 mole%, preferably from 18 mol% to about 9 mol% methyl diallyl ammonium acetate and 4) the prepolymers prepared from about 70 mol% to about 95 mol%, preferably 70 mol% to about 88 mol% acrylamide and about 30 mol% to about 5 mol%, preferably o about 30 mole% to about 12 mole% methacryloyloxyethyl trimethylaimonium ethyl sulfate.

Water-soluble cationic prepolymers are easily and quickly prepared by simultaneously adding the desired monoramers in the desired amounts and a water-soluble free radical polymerization initiator, each in an aqueous solution, to a reaction vessel with water which is held at a temperature from about 80 ° C to about 90 ° C. Suitable free radical polymerization initiators have been used heretofore to prepare graft copolymer particles of the invention and have been mentioned above. The amount of initiator used will be such that it is sufficient to obtain water-soluble cationic prepolymers with an RSV value of 7909239

, Λ * V

-10-21083 / Vk / µl about 0.1 to about 2.5, preferably from 0.1 to about 1.0, measured as a 1% solution in 1 M NaCl at a temperature of 25 ° C.

In some instances, it is desirable to have reactive functionalities, which means reactive groups on the surface of the graft copolymer particles. The reactive groups generally increase the bonding properties of the graft copolymer in particulate form.

The preferred reactive groups are those that react with cellulose.

The reactive groups can be introduced into the cationic monomer before the preparation of the prepolymer takes place or they can be introduced into the prepolymer after its preparation or they can be introduced into the graft copolymer after its preparation.

Cellulose reactive groups which can be introduced by reaction with an epihalohydrin such as epichlorohydrin with polymers having secondary amine functionality or tertiary amine functionality or both. Reactive groups effected by epihalohydrin can be an epoxide, the halohydrin form of the epoxide or an azetedinium group.

Reactive groups can be introduced through an aldehyde such as formaldehyde, glyoxal and gluturaldehyde with amide functional polymers such as the prepolymers prepared by copolymerizing a cationic monomer and acrylamide or polymers having a secondary amine function such as in prepolymers which prepared from diallylamine salts. Using dialdehydes. like glyoxal, the reactive group will be an aldehyde. When using formaldehyde, the reactive group will be the N-methylol.

The amount of the functional agent used to effect the reactive groups on the graft copolymer particles of the invention will be from about 0.25 mole to about 3 moles, preferably from 1 mole to about 2 moles for each mole of amide or amine function .

The reaction will be carried out at a temperature between about 20 ° C and about 60 ° C at a temperature between about 8 and 10 except when formaldehyde is used as a functional agent because then the reaction will be carried out at a pH of about 2- 3.

The reactive groups can improve the paper etching by providing an agent for the graft copolymer particles that react with cellulose fibers. Conventional fillers decrease the paper strength of 7909239 -11-21083 / Vk / µl by interacting the bond between the cellulose fibers. By using graft copolymer particles with cellulose reactive groups, it is possible to obtain a higher paper strength for the bonding between the fibers by the reactive functional groups on the particles.

The amount of prepolymer used for the preparation of the graft copolymer according to the invention can vary from 1 wt. parts to about 25 parts by weight per 100 wt. parts of monomer used. The preferred amount is about 2 to 10 parts of prepolymer 10 for 100 * parts of monomer.

Graft copolymerization is performed by adding monomer to an aqueous solution of water-soluble cationic prepolymer in the presence of a free radical polymerization initiator. The water-soluble prepolymer may be present anally in the reaction bath at the start of the operation or may be added in whole or in part simultaneously with the monomer. The initiator is usually added continuously together with the monomer. The total reaction time can vary from about one hour to about 24 hours, and preferably this time is between 2 and 6 hours. The latex prepared according to the invention will have a solid content from about 15% to about 60%. The preferred amount of water used in preparing the latex will be such as to obtain a latex having a solids content of about 25 to about 55%. In some cases it is possible to dry the latex to a fine powder. In these cases, the powder can be redispersed in water and then added to the pulp slurry before paper formation is accomplished. Drying the latex to a fine powder is usually not possible when the graft copolymer particles have reactive functions.

The final product is a stable suspension of substantially spherical graft copolymer particles in water. According to the invention, the graft copolymer particles can be prepared which have a particle size ranging from about 0.1 µm to about 2 µm.

A large number of chemical polymerization initiators can be used to prepare the latex according to the invention, in particular using peroxy compounds. Preferably the initiator is water soluble.

Suitable water-soluble initiators include materials which are heat activated 7909239-12-2283 / Vk / µl * such as sodium persulfate and ammonium persulfate. The polymerization is carried out at a temperature usually at 70-95 ° C with these initiators. Other water-soluble initiators are those comprising the so-called redox initiator stones such as ammonium persulfate-sodium bisulfite-iron (U) ion and t-butylhydro-peroxide-sodium formaldehyde sulfoxylate. Rediox initiators are activated at relatively low temperatures and polymerizations using such systems can be carried out at a temperature between 20 and 80 ° C. The amount of initiator commonly used is known to a person skilled in the art. Normally about 0.1 part to about 5 wt. parts initiator used at 100 wt. parts monomer. The invention will be further elucidated by means of the examples. Hereby, organic pigments are obtained which are finely divided particles obtained by graft copolymerization of an ethylene-unsaturated monomer such as styrene, on a water-soluble cationic prepolymer in an aqueous solution and in the presence of a free radical polymerization initiator.

Example I

A polymerization vessel equipped with a water-cooled jacket, further equipped with a thermometer, stirrer, reflux condenser and dropping funnels, was charged with 87.0 g of distilled water.

The dropping funnels were successively filled with: 1) 71.25 g of acrylamide (1.0 mol) in 166.0 g of distilled water, 2) 3.75 g of dimethyl di-di-ammonium chloride (DMDAAC, 0.023 mol) in 8.75 g distilled water and 3) 1.88 g of ammonium persulfate (0.008 mol) in 35.6 g of distilled water.

The contents of the vessel were heated to a temperature of 85-8-9 ° C and the contents of the three dropping funnels were added dropwise over a two hour period. After heating for an additional 15 minutes, the solution was cooled to room temperature (about 23 ° C). The product in solution contained 21.9 solids and had an RSV value, reduced specific viscosity, of 0.32, measured as 1 µl solution in 1M NaCl at 25 ° C.

A polymeria vessel equipped with a water-cooled jacket and with a thermometer, stirrer, cooler and three dropping funnels was charged with 493.0 g of distilled water and 54.4 g of a 10 3Ê solid solution of the above copolymer (5.44 lb dry copolymer 7909239-13 2 1 083 / Vk / µl polymer). The dropping funnels were filled with: 1) 164.0 g of a 10% solid solution of the above copolymer (16.4 g of dry copolymer), 2) 218.0 g of styrene and 5) 6.0 g of ammonium persulfate in 24.2 g of distilled water.

The contents of the vessel were stirred and heated to a temperature of 88 ° C. The contents of the three dropping funnels were added to the polymerization vessel over a period of three hours, while keeping their temperature at 88-93 ° C. After heating again for 15 minutes, the product was cooled to room temperature.

The product was a white latex with 25.2% solids. About half of the latex of dialialized using regenerated 48X cellulose membrane to remove unreacted water-soluble prepolymer.

A sample of 240.0 g of dialized latex (50.0 g of dry polymer, 0.056 mol of acrylamide) was placed in a reaction vessel and the pH adjusted to change the value from 4.2 to 9.1 by 0, 9 ml of 1M NaOH solution. Glyoxal (16.2 g of a 40% aqueous solution, 0.112 mol) was added, and the pH was changed from 6.2 to 9.0 with 0.8 ml of 1 M sodium hydroxide solution. Water was added in an amount of 56 ml to reduce the solid in the reaction mixture.

The mixture was heated to a temperature of 50 ° C for 4 hours, and the pH was then lowered to 2.0 with 0.5 ml of concentrated hydrochloric acid. The final product contained 18.2% solid.

Examples II-V.

Four other latexes were prepared according to the procedure outlined in Example I, except that the ratio of the acrylamide to DMDAAC was varied as indicated in Table A.

(see table A on page 14).

Example VI

The compositions indicated in Examples 1-9 were tested for activity as a paper filler. Paper for paper towels and the like was manufactured on a Noble & '

Wood handsheet device. The pulp consisted of a 50:50 blend of 35 bleached hardness: bleached eight-wood pulp crushed into a 300 cc Canadian Standard Freeness. The paper was adjusted to a pH value of 4.5 with sulfuric acid without alum. The latex was tested for addition levels of 4% and 8ί (dry basis). The control was accomplished with 7909239 -14-21083 / Vk / µl

k »♦ -V

Table A.

______ prepolymer__ molar ratio acrylic- DMDAAC ^ 4½ acrylamide:% 5 example amide (g) (g) S2 ° 8 DMDAAC TS * 2) RSV * 3 I 71.25 3.75 1.88 97.75: 2.25 21.9 0.32 II 67.5 7.5 1.88, 95: 5 21.7 0.37 III 60.0 15.0 1.88 90:10 21.6 0.28 IV 56.3 18.7 1 , 88 87: 13 21.4 0.24 10 V 37.5 37.5 1.88 70: 30 21.3 0.18 starting latex 10% pre-,% solid particles polymer polymer styro-Sxa size 15 example solution (g) reen. ^ 2¾ ^ duct lysé (»m) * 1) I 218.4 218 6.0 25.2 20.8 0.4-0.6 II 218.4 218 6.0 25.9 21.3 0.4 -0.6 III 218.4 218 6.0 26.1 19.7 0.4-1.0 IV 218.4 218 6.0 26.0 18.3 0.5-0.8 20 V 218, 4 218 6.0 25.2 17.6 0.8-1.26 modified latex dialysed 40% glywater solid example latex (g) oxal (g) (g) product ^ 25 '11 .... ...... ....... 1 ..... Ü - I 240.0 16.2 56.0 18.2 II 234.0 13.9 60.0 18.2 i III 253 .0 12.2 39.0 18.3 IV 218.0. 9.2 14.0 18.3 V 226.6 5.8 2.0 17.9 30

Notes: * 1) Particle size was measured with transmission electron microscope * 2) T.S. s total solids content * 3) RSV (reduced specific viscosity) measured as a 1 µl solution in 1M NaCl at a temperature of 25 ° C.

7909239 -15- 21083 / Vk / jl unfilled paper and paper filled with 10% and 20% kaolin clay. The clay was retained using 1% alum and 0.05% of a high molecular cationic polyacrylamide as a retention aid. The results obtained are summarized in Table B.

5 Table B dry

Basis weight -_ tensile wMullen (lb./3000? Opaque strength burst "

filler (%) sq. ft.) ness * 1) (£) flb./in) (psO

none 39.4 73.6 18.6 32.4 10 kaolin clay (10) * 2) 41.9 80.3 15.0 25.7 (20) 2) 44'6 84.5 13.5 22, 4 example I (4) 39.6 74.3 19.6 36.3 (8) 40.5 75.1 19.8 34.3 example II (4) 40.0 78.0 19.9 37.3 (8) 40.7 82.7 .20.2 38.1 15 Example III (4) 40.1 80.0 20.4 37.3 (8) 41.4 85.1 .19.8 34.5 Example IV (4) 40.2 81.5 19.2 34.3 (8) 41.6 86.3 19.0 33.9 Example V (4). 40.2 79.3 19.7 34.3 (8) 41.1 83.8 18.4 33.9 20 Notes: * 1) Opacity was measured according to Tappi Standard T-425 (Hunter Opacity Meter).

* 2) retention agent: alum (1ί) plus cationic polyacrylamide (0.05%) (no retention agent was used in the other examples in this table).

Examples VII-X

Four latexes were prepared by following the procedure described in Example I using 10% different acrylamide-DMDAAC eopolymers. The latexes were not reacted with glyoxal. The conditions for the synthesis of the latex are indicated in Table C.

Example XI

The graft copolymers of Examples VII-X were tested as a paper filler according to the procedure described in Example VI. The results obtained are shown in Table D.

35 Examples XII-XVI

Various latexes were prepared following the procedure set forth in Example I except that the water-soluble prepolymers were used to prepare the graft copolymers copolymerizing 7909239 ♦> -16-21083 / Vk / jl acrylamide and raethacryloyloxyethyl trimethyl ammonium methyl sulfate (MTMMS). The reaction conditions are shown in Table E. The latexes were not reacted with glyoxal. The properties are listed in Table F.

Example XVII

The graft copolymer particles of Examples XII-XVI were tested as a filler for paper according to a method described in Example VI. A commercially available polystyrene latex was used as an additional control in this experiment. The particles in the polystyrene latex have a negative charge and as a result of this a retention aid was used as mentioned. ...

Example XVIII

Clay and a commercially available polystyrene latex were tested as a filler for paper by the method of Example VI. The two fillers were both tested with and without a cationic polyacrylamide retention aid. The test results are summarized in Table C.

Table C

___ Water-soluble polymer_ molver (ΝΗ ^) 2 attitude 20 acrylic „Q acrylamide DMDAAC 2 amide:%

example (g) (g) (g) DMDAAC T.5. Stainless steel

VII 60.0 15.0 1.88 90:10 21.6 0.28 .Vin 56.3 18.7 1.88 87: 13 21.4 0.24 IX .46.9 28.1 1.88 79: 21 21.3 0.24 '25 X 37.5 37.5 1.88 70: 30 21.3 0.18 _Latex_ 10% copolymer (ΝΗ ^) 2% particles solution styrene _ n, fixed size 30 example (g) - (g) z 8 g; substances (pm) VII 218.4 218 6.0 26.1 0.4-1.0 * 1) VIII 218.4 218 6.0 26.0 0.5-1.0 # 1) IX 218.4 218 6.0 25.7 ~ 0.5 * 2) X 218.4 - 218 6.0 26.2 0.8-1.26 * 1) 35 Notes: * 1) the particle size was measured by transmission elec - thrones microscopy * 2) the particle size determined by light microscopy T.'S. the total solids content is 7909239 -17-21083 / Vk / µl

Table_p dry basis weight tensile "Mules (lb / 3000 opaque burst strength" filler (?) Sq.ft.) * 1) (?) (Lb.7in) (psi) none 40.7 75.2 16.3 31.4 ^ Olaolin clay (10) 42.7 79.1 14.7 26.4 * 2) (20) 44.3 81.0 15.3 25.0 Example VII (4) 41.7 80.2 16.9 30.1 (8) 42.9 84.5 15.7 23.1 Example VIII (4) 41.6 81.7 15.7 30.0 (8) 42.8 86.0 15.2 26.6 ^ example IX (4) 41.8 81.6 15.3 28.8 (8) 42.9 86.3 14.1 25.9 example X (4) 41.2 79.3 15.5 28.0 (8) 41.9 82.9 15.1 27.9

Notes: * 1) Opacity was measured according to Tappi Standard T-425 j (Hunter Opacity Meter) * 2) retention agent: alum (1%) plus cationic polyacrylamide (0.05 t) (no retention agent was used in the other examples in this table ).

Table E

20 - water-soluble polymer ___ mole thickening) attitude acrylic g acrylamide MTMMS 28 amide:%

example (g) (g) (g) MTMMS T.S. RSV

25 XII 120.0 180.0 22.5 70; 30 21.6 0.16 XIII 150.0 150.0 22.5 78: 22 21.6 0.154 XIV 210.0 99.0 22.5 88: 12 21.8 0.187 XV 225.2 74.8 22, 5 91: 9 21.7 0.143 XVI 255.0 45.0 22.5 95: 5 21.7 0.168 30 _Latex_________ 1® ï (Mtl) copolymer 42% particles solution styrene Sp0o (g) fixed size example (g) < ._ (g) _ substances (pm) XII 2402 2398 66.0 26.0 0.8 35 XIII 2402 2398 66.0 25.6 0.8 XIV 2402 2398 66.0 25.6 0.7 XV 2402 2398 66.0 25.6 0.8 XVI 2402 2398 66.0 24.7 0.8 7909 239 _18- 21083 / Vk / yl

Notes: * 1) the particle size was determined by turbidity reading according to the method of A.B. Loebel (Official Digest, 200, February 1959) T.S. = the total solids content of 5 RSV a (reduced specific viscosity) measured as a 1-solution in 1M NaCl at a temperature of 25 ° C.

Table F Dry Basis Weight Tensile "Mules (lb / 3000 Opaque, Burst" 10 Filler (%) sq.ft.) * 1 (¾) (lb./in) (psi) None; 39.9 79.6 18.2 30.5 Kaolin clay (10) 44.5 86.0 13.9 21.5 * 2) (20) 48.9 89.4 11.6 16.5 Example XII ( 4) 40.6 85.0 17.5 29.1 (8) 42.1 89.4 14.8 24.4 15 Example XIII (4) 40.7 85.1 17.9 30.4 (8) 41.4 89.1 16.0 33.0 Example XIV (4) 40.8 83.9 17.2 29.5 (8) 41.4 88.0 15.4 26.6 Example XV (4) 39 , 6 81.0 18.4 31.1 (8) 40.6 83.9 18.3 31.9 20 Example XVI (4) 39.6 78.3 17.3 32.6 in trade <8> 39.5 78.5 17.9 30.8 available (4) 40.9 86.5 15.5 24.0 polystyrene * i) (8) 43.0 90.6 14.1 19.9

Notes: * 1) Opacity was measured according to Tappi Standard T-425 25 (Diano Opacity Meter) * 2) retention agent: alum (1%) plus cationic polyacrylamide (0.05%) (no retention agent was used in the other examples in this table ).

Table G

- dry 30 retention _ _ basis weight opaque tensile- "Mules auxiliary _" '. (lb / 3000 heights * 1) burst strength "filler (%) means ______ · sq.ft.) __ (¾) ΠΗ. / ίηΙ ( psi) _ clay 6 (1i) 40.3 75-9 16.2 28.9 kaolin alu (1% plus, 42.8 80.4 16.2 26.7 35 clay (10) cationic polyacrylamide commercially available (°) »° 5 available ^) alum (1%) 39> 8? 6> 3 18> 9 30.6 polystyrene 7909239 -19-, 21083 / Vk / jl

Table G continued.

retention basis weight opaque dry "Mules auxiliary (lb / 3000heid * 1) pull burst" filler (%) means sq.ft) _ (%) strength (psi) TOrkriSiE (1 *> Plua '^ -8 8015 18 »3 29, »'pilyatfreei oationisoh 5 (4) polyacrylamide (0.05 *)

Notes: * 1) Opacity was measured according to Tappi Standard T-425 (Hunter Opacity Meter)

10 Example XIX

Dimethylaminoethyl methacrylate in an amount of 157 g was added dropwise to 98 g of 37% hydrochloric acid. Cooling was necessary to keep the temperature below 30 ° C. Then 381 cc of water and 12.2 cc of isopropanol were added to obtain a 30-solution. This solution was heated to 50 ° C and purged with nitrogen for 30 minutes, after which the mixture was heated to 75 ° C and 3.6 cc 0.1 M FeS0jj.7H2Q was added followed by the addition of 10.9 cc t -butyl hydroperoxide (90%). When the addition of the catalyst was finished, the solution was stirred for 30 minutes, and cooled to room temperature. The viscous solution was diluted to 50.85% fresh matter. The RSV value is 0.53 (1M NaCl, 1%, 25 ° C).

A 2 liter water-cooled reaction vessel fitted with a thermometer, stirrer, cooler and three dropping funnels was charged with 269 cc of distilled water. The dropping funnels were filled with: 25 1) 183 g of a 12.3% aqueous solution of the poly (methaeryloyloxyethyldimethylammonium chloride) prepared as indicated above, 2) 225 g of styrene and 3) 6 g of ammonium persulfate in 25 cc of distilled water .

The contents of the vessel were stirred and heated to 88 ° C under nitrogen. The contents of the dropping funnels were added dropwise over a period of 2 hours, keeping the temperature of the reaction vessel at 88-95.5 ° C. After heating for an additional 15 minutes, the product was cooled to room temperature. The final product was free of styrene and had a solids content of 36.4%.

Example XX

Poly (methacryloyloxyethyldimethylammonium chloride) was prepared 7909239 -20-21083 / Vk / µl as indicated in Example XIX, except that the solution was diluted to 30% solid instead of 15.85% solid. 161.5 g of this 30% solution was placed in a reaction vessel with 359 g of distilled water. The pH of the solution was changed from 1.9 to 1.0 with 3.6 cc of concentrated HCl. Epichlorohydrin was added in the amount of 34.7 g to the reaction vessel to obtain a 15% reactive solid. This mixture was stirred for 6.5 hours, after which time the pH rose to 7.6. The pH was then adjusted to 0.5 with 13.7 cc of concentrated HCl. The solids content was 12.3%.

Ί0 A 2 L polymerization vessel equipped with a water jacket and with a thermometer, stirrer, cooler and 3 dropping funnels was charged with 269 cc of distilled water. The dropping funnels were filled with: 1) 183 g of a 12, 3.3, -8% aqueous solution of the water-soluble epichlorohydrin modified prepolymer prepared as indicated above 15, 2) 225 g of styrene and 3) 6 g ammonium persulfate in 25 cc of distilled water.

The contents of the vessel were stirred and heated to 89 ° C under nitrogen. The contents of the dropping funnels were added dropwise over a period of 2 hours as the vessel temperature was maintained at 89-97 ° C. After heating for an additional 15 minutes, the product was cooled to room temperature. The final product was free of styrene and had a total solids content of $ 36.8.

Example XXI

A reaction vessel was charged with 4130 g of distilled water and 145.5 g of a 51.95 55-aqueous solution of poly (methyl-diallyl ammonium chloride). The contents of the vessel were heated to 87 ° C under nitrogen. 228 g of Poly (methyl diallyl ammonium chloride) in 1597 g of distilled water, 3040 g of styrene and 83.7 g of ammonium persulfate in 338 g of distilled water were added dropwise simultaneously over a period of 2 hours. The temperature was kept at 87-100 ° C. The contents of the vessel were stirred for an additional 15 minutes, cooled to room temperature and filtered through a 100 mesh (150 µm) sieve.

The latex obtained had a solids content of 37.2% and a particle size of 0.5 microns measured by the Loebel method (see Table E).

806.5 g of the above latex (300 g of solid) was placed in a reaction flask and the pH was changed from 1.6 to 1.1 with 8.8 cc of concentrated 7909239-21-21083 / Vk / µl hydrochloric acid . 3¾> 2 g of Epichlorohydrin was added and the mixture was stirred at room temperature. When the reaction took place, the pH rose to 7.3 at which time the pH was adjusted to 1.55 with concentrated hydrochloric acid. The latex obtained had a solids content of 37 ί.

Example XXII

A reaction vessel was charged with 200 g of distilled water, 0.24 g of acetic acid, 3.64 g of sodium acetate and 1 g of isopropanol. This mixture was heated to 60 ° C under nitrogen and kept at this temperature for 15 minutes. Methylolacrylamide (40 g in 160 g distilled water), methyl diallyl amononi chloride (13.3 g in 53 1 g distilled water) and aranonium persulfate (0.8 g in 20 g distilled water) were added dropwise simultaneously over a period of 1.8 hours followed by stirring for 1 hour. The viscous copolymer solution was cooled to room temperature and the pH was adjusted from 5.0 to 7.2 by adding 1.4 cc of 5 M NaOH. The total solids content of the reaction mass was 12.8%. The latex synthesis consisted of adding to a reaction vessel in which 493 g of distilled water was added, 54.5 g of a 10% aqueous solution of the copolymer prepared above and heated to 89 ° C under nitrogen. To this was added 164 g of a 10-aqueous aqueous copolymer solution as indicated above, 218 g of styrene and 6 g of ammonium persulfate in 24.2 g of distilled water, which substances were added simultaneously over a period of 2 hours. The temperature was kept at 89-96 ° C. After stirring for 15 minutes, the latex was cooled to room temperature and filtered through a 500 mesh sieve (150 µl). This filtered off latex had a solids content of 26%.

Example XXIII

A reaction vessel filled with 200 g of distilled water, 0.24 g of acetic acid, 3.64 g of sodium acetate and 1.5 g of isopropanol. The mixture was heated to a temperature of 60-62 ° C under nitrogen and kept at this temperature for 5 minutes. 40 g of methylolacrylamide in 160 g of distilled water, 13.3 g of dimethyldiamyl ammonium chloride in 53.1 g of distilled water and 0.8 g of aniurea sulfate in 20 g of distilled water were added simultaneously, which was done dropwise over a period of 2 hours, after which the mixture was stirred for another 1 hour. The copolymer solution, which had a solids content of 12.3%, was cooled to room temperature and the pH was adjusted to 7.3 with 7909239 f-22-21083 / Vk / µl 0.5 cc 5 M NaOH. A reaction vessel was charged with 439 g of distilled water, 54.4 g of a 10% aqueous solution of the above copolymer. The contents of the reaction vessel were heated to 88-90 ° C under nitrogen. 164 g of a 10% aqueous solution of the above copolymer, 218 g of styrene and 6 g of ammonium sulfate in 24.2 cc of distilled water were added dropwise simultaneously over a period of about 2 hours to the reaction vessel. After the addition ends. The contents of the reaction vessel were stirred for 15 minutes and cooled to room temperature. The latex obtained had a solids content of 25.4%.

Example XXIV

A reaction vessel was charged with 170 cc of distilled water and heated to 85 ° C under nitrogen. After passing the nitrogen for 15 minutes, 110.3 g of acrylamide in 257.3 cc of distilled water, 133.2 15 g of methyl diallyl ammonium acetate of a 29.8% aqueous solution, and 7.5 g of ammonium persulfate in 7T, 3 cc of distilled water were added dropwise simultaneously over a period of 1.75 hours, after which the mixture was further stirred for 15 minutes and then cooled. The solid content was 20.4%, the RSV value was 0.35 (1M NaCl, 20 1 25 ° C).

The latex synthesis consisted of supplying 798 cc of distilled water and 1308 g of a 10% aqueous solution of the copolymer prepared as indicated above to the reaction vessel. This was heated to 93 ° G under nitrogen. 1308 g of styrene, 14.6 g of t-bptyl-25 hydroperoxide in 127.6 g of distilled water and 14.4 g of sodium formaldehyde sulfoxylate in 127.8 of distilled water were simultaneously added dropwise over a period of 3 hours, after which the mixture was stirred for another 15 minutes and cooled to room temperature. The latex was filtered through a 100 mesh sieve (150 µm). The solid content was 39.7%. The particle size is 0.65 / um, measured according to the Loebel method, see table E.

Example XXV

The glyoxal modification of the latex as indicated in Example XXIV was performed as follows. 214 g of the above latex were placed in a reaction vessel. The pH was changed from 4.9 to 8.5 with 1.4 cc of 5 M NaOH. 9.3 g of glyoxal in 13.9 g of distilled water was then added to give the pH a value of 6. It was reset to 8.5 with 1.3 cc 5 M NaOH. The latex-glyoxal mixture was stirred 7909239-23-21083 / Vk / µl while the pH was maintained at 8.5 with the addition of periodic acid in a total amount of 0.2 cc 5 M NaOH. After about 30 minutes, the viscosity had increased from 31 to 60 cps. The reaction was ended by adding 0.4 cc of concentrated HgSO 4. The solid content was 39.2%.

Example XXVI

The latex mentioned in Examples XXIV and XXV was further investigated as a filler for paper using a method described in Example VI. The results obtained here are summarized in Table H.

Table H.

basis weight "Want opaque (lb / 3000 tensile burst" strength ** filler sq.ft.) (lbs./in.) (psi) (¾) none 40.4 17.7 30.9 79.4 15 example XXIV ( 4) 41.2 17.4 32.5 86.2 Example XXIV (8) 42.3 15.0 27.4 8-9.2 Example XXV (4) 41.5 19.5 35.9 86.3 example XXV (8) 42.3 17.6 30.9 $ 9.3 kaolin clay * (10) 44.2 15.2 22.0 86.2 20 kaolin clay (20) 47.6 12.6 17.9 89.4

Note: * 0.05% of a cationic polyacrylamide, based on the weight of the paper, was used as a retention aid for the kaolin clay.

25 ** opacity measured according to Tappi standard T-425 (Diano

Opacimeter).

Example XXVII

A polymerization vessel, equipped with a water jacket and with a thermometer, a stirrer, a cooler and four dropping funnels, was charged with 30.0 g of distilled water, 0.6 g of acetic acid and 0.85 g of sodium acetate. The dropping funnels were filled with: 1) 60.0 g of styrene 2) 6.0 g of chitosan, 6.0 g of acetic acid and 114.0 g of distilled water, 3) 0.65 g of a 20% aqueous solution of t-butyl hydroperoxide and 25.0 g of distilled water, and 4) 0.65 g of sodium formaldehyde sulfoxylate and 25.0 g of distilled water.

7909239 * "-24- 21083 / Vk / jl

The contents of the reaction vessel were stirred and heated to 88 ° C. The contents of the four dropping funnels were added dropwise over a period of 4 hours keeping the temperature of the vessel at 60 ° C. After heating for an additional 30 minutes, the product was cooled to room temperature and all unreacted styrene was removed using a rotary evaporator. The product was a latex with a solid content of 28.8%. The particles of this latex were tested as a paper filler according to the method indicated in Example VI. The results obtained are shown in Table J.

Table J

basis weight opaque tensile strength "Mules (lb / 3000heid ** burst" filler sq.ft) {%) (lbs / n.) (psi) none 40.6 80.0 18.8 31.9 15 example XXVII (4 ) 40.8 84.1 18.5 28.8 Example XXVII (8) 41.9 86.6 17.7 28.5 Kaolin clay * (10) 44.6 85.7 15.2 23.0 Kaolin clay (20) 46.3 & 7.5 13.3 18.6 commercial poly-U1 n ς 17 7 s 20 styrene * (4) 41 ° 83'5 17'7 28'5 commercial poly1. - - 1Λ, w, styrene (8) 41'2 86'1 16'3 26'3

Notes: * 0.05% cationic polyacrylamide based on the weight of paper was used as a filler retention aid. ** Opacity was measured according to Tappi standard T-425 (Hunter Opacitext meter).

The clear advantages of the organic pigments according to the invention can best be shown by studying the data as mentioned in Tables A and B. The organic pigments were added in amounts of 4 and 8% and were compared with kaolin clay added in amounts of 10% and 20% (equivalent to 4% and 8% of the organic pigments of the invention). Alum and high molecular weight cationic polyacrylamide were used as recovery aids for the kaolin clay. No retention aid was used with the organic pigments of the invention. The opacity of the filled paper is a measure of the retention of the filler in the paper. The dry tensile strength and the "Mullen burst" data in Table B.

7909239 V * -25-21083 / Vk / jl illustrate the strength benefits obtained with the organic pigments of the invention. It will be clear that with the kaolin clay the strength properties decrease compared to the unfilled paper by 20-30%. Against this, it appears that the organic pigments of the invention provide the highest opacity (compositions of Examples C and D) and strength improvements of 5-1% over unfilled paper are also achieved.

When these organic pigments are compared to clay 10, the former give opacity equivalent to the latter and further have strength properties 20-50% higher than the latter.

Another advantage of the fillers (organic pigments) according to the invention is evident from Table B. The clay-filled papers are considerably heavier than the comparative compositions, while the paper with the filler according to the invention is only slightly heavier than the paper composition serves as a comparison.

The data in Tables C and D summarize the results of comparable series of organic pigments stabilized using acrylamide dimethyl diallyl ammonium chloride copolymers as the water-soluble cationic prepolymers that have not reacted with glyoxal. Since there is no reactive functionality on the particles, the strong properties deteriorated in this experiment than in the previous one.

The data in Tables E and F summarize similar experiments using the organic pigments using various copolymers of acrylamide and methacryloyloxyethyl trimethyl ammonium methyl sulfate as the water-soluble cationic prepolymer. Since there was no reactive functionality on the particles, the strong values were slightly worse than in the blank determination in some cases, but always significantly better than for the clay-filled paper. For further comparison, a determination was made with commercially available polystyrene latex. The particles in this latex have an anionic charge such as alum and a polymeric retention aid was used. The data shows that the polystyrene particles gave a paper type with a slightly higher opacity than the organic pigments according to the invention, but also with a higher basis weight. The polystyrene particles decreased the paper strength, although 79 0 92 39 -26-. 21083 / Vk / jl not as much as clay.

From the data of Table G it appears that a summary has been obtained of the data with respect to the conventional fillers such as clay and polystyrene, wherein retention agents are required for optimal behavior. Without retention agents, opacity is very low in both cases. As can be seen from Tables B, D and F, the organic pigments of the invention provide good opacity without the use of a retention aid.

Example XXVIII

10 A reaction vessel equipped with a water cooling jacket and equipped with a thermometer, stirrer, cooler and dropping funnels. filled with 89 g of distilled water and 436 g of a 10% aqueous solution of poly (methyl diallyl ammonium chloride). The resulting solution was heated to 87-88 ° C by circulating hot water through the water jacket of the reaction vessel. 425.2 g of styrene and 10.9 g of divinylbenzene were mixed and placed in the dropping funnel. 13 g of a 90% aqueous solution of t-butyl hydroperoxide and 108 g of distilled water were placed in a burette and 13.6 g of sodium bisulfite dissolved in 124.5 g of distilled water in another burette. The mixture of styrene and divinylbenzene, the t-butyl hydroperoxide solution and the sodium bisulfide solution were added dropwise simultaneously over a period of 2 hours to the contents of the reaction vessel. After stirring for 20 minutes, a slight odor of styrene was noticeable. Further, a solution of t-butyl hydroperoxide (3.4 g of t-butyl hydroperoxide dissolved in 27 g of distilled water) and further a solution of sodium bisulfite (3.4 g of sodium bisulfite dissolved in 31 g of distilled water) was added to the reaction mass and the reaction mass was stirred for another 20 minutes. The resulting latex was cooled to room temperature and filtered through a 100 mesh (150 µm) screen. The solids content was 27.7%. The particle size was 0.8 µm measured with a Coulter Counter.

As mentioned above, polyethylene-like unsaturated monomers, such as divinylbenzene, can be used in mixtures with monoethylene-like unsaturated monomers, to obtain cross-linked graft copolymer particles. Examples of other suitable polyethylene-like unsaturated monomers that can be used for this purpose are diallyl phthalate, ethylene glycol dimethacrylate, 1,3-bytylene glycol dimethacrylate, 1,6-hexanediol dimethacylate, polyethylene glycol dimethyl acrylate, 7909239-27-23-283 / Vk / methyl acrylate, polypropylene glycol divinyl naphthalene, diallyl maleate, diallyl fumarate, trimethylol propane trimethorylate and pentaerythritol tetraacrylate. The preferred polyethylene-like unsaturated monomers, referred to as the cross-linking monomers, are divinyl benzene, diallyl phthalate, ethylene glycol dimethacrylate and 1,3-butylene glycol dimethacrylate.

Although the organic pigments of the invention are particularly suitable as a paper filler, they can also be used in paper coatings together with a suitable binder for this. Furthermore, they can be used in: paints, inks and the like. They can also be used as a coating together with a suitable binder on glass surface, metal surface, wooden surfaces, plaster and the like. Example XXIX

A polymerization vessel equipped with a water jacket and equipped with a thermometer, stirrer, cooler and 3 dropping funnels was filled with 75.0 g of distilled water. The dropping funnels were filled as follows: 1) the first dropping funnel with 35.0 g of acrylamide (0.49 mol) in 70.0 g of distilled water, 2) the second with 15.0 g of vinyl benzene trimethyl ammonium chloride (0.07 mol) in 60.0 g of distilled water, and 3) the third with 1.25 g of ammonium persulfate in 50.0 g of distilled learned water.

The contents of the reaction vessel were heated to 80 ° C and the contents of the dropping funnels were added dropwise over a period of 2 and a half hours, maintaining the temperature at 80-85 ° C. After heating for an additional 30 minutes, the solution was cooled to room temperature (about 23 ° C). The product solution contained 22.0% solids and had an RSV value (reduced specific viscosity) of 0.27 (1% solution in 1 M NaCl, 25 ° C).

A reaction vessel equipped with a water jacket and equipped with a thermometer, stirrer, cooler and 3 dropping funnels was charged with 503.8 g of distilled water and 26.2 g of the above copolymer solution (5.8 g of dry copolymer). The dropping funnels were filled with: 35 first dropping funnel 78.6 g of the above-mentioned copolymer solution (7.3 g dry polymer) plus 120.0 g of distilled water, dropping funnel two with 230.0 g styrene and dropping funnel three with 5.1 g aramonium persulfate in 120.0 g 7909239-28-21083 / Vk / µl distilled water.

The contents of the reaction vessel were stirred and heated to 79 ° C. The contents of the three droplet droppers were added dropwise over a period of 4 hours keeping the temperature of the reaction vessel at 79-88 ° C. After heating for an additional 15 minutes, the product was cooled to room temperature and the pH changed from 1.9 to 7.5 with the addition of 25% sodium hydroxide solution. The product was filtered through a 100 mesh (150 µm) screen. The product was a white latex with 25.1% solids and an average particle size of 0.62 µm (method of A.B. Loebel, Official Digest, 200, February, 1959).

Example XXX

A reaction vessel equipped with a water jacket and with a thermometer, stirrer, cooler and two dropping funnels was charged with 20 g of distilled water. The dropping funnels were filled as follows: dropping funnel 1 with 77.0 g of acrylamide (1.08 mol), 17.1 g of 4-vinylpyridine (0.16 mol) and 16.0 g of concentrated hydrochloric acid solution (0.19 mol) in 200 g of distilled water, and dropping funnel 2 with 2.5 g of ammonium persulfate in 100 g of distilled water.

The contents of the reaction vessel were heated to 80 ° C and the contents of the dropping trehers were added dropwise over a period of about 2 hours and 25 minutes, keeping the temperature at 80-85 ° C. After heating for 30 minutes, the solution was cooled to room temperature (about 23 ° C). The product solution contained 21.6% solid and had an RSV value, reduced specific viscosity, of 0.34 (1% solution in 1 M NaCl, 25 ° C).

A reaction vessel equipped with a water jacket and with a thermo-meter, stirrer, cooler and three dropping funnels was charged with 503.4 g of distilled water and 26.6 g of the above copolymer solution (5.7 g of dry polymer). The dropping funnels were filled as follows: dropping funnel 1 with 79.8 g of the above copolymer solution (17.2 g of dry copolymer) plus 120 g of distilled water, dropping funnel 2 with 230 g of styrene and dropping funnel 3 with 5.1 g of ammonium persulfate in 120.0 g of distilled water.

The contents of the reaction vessel were stirred and heated to 78 ° C. The contents of the dropping treuthers were added dropwise simultaneously at 7909239-29 "21083 / Vk / µl. The contents of dropping funnel 1 and 2 were added over 4 hours. The contents of dropping funnel 3 were added over a period of 4 hours and 15 minutes. The temperature of the reaction vessel was kept at 78-84 ° C during the addition of the substances from the 5 dropping funnels. The product was cooled to room temperature and the pH changed from 2.0 to 4.6 with 10% sodium hydroxide solution. The product was filtered through a 100 mesh (150 µm) screen. The product was a white latex with 25.8% total solid and with an average particle size of 0.45 µm (Loebel method, Official Digest, 10 200, February 1959).

Example XXXI

A reaction vessel equipped with a water jacket and with a thermometer, stirrer, cooler and two dropping funnels was charged with 200 g of distilled water. The dropping funnels were filled as follows: 15 dropping funnel 1 with 69.0 g of acrylamide (0.97 mol) and 31.0 g of methacrylamidopropyltrimethyl ammonium chloride (0.14 mol) in 200 g of distilled water and dropping funnel 2 with 2.5 g of ammonium persulfate in 100 g distilled water.

The contents of the reaction vessel were heated to 77 ° C and the contents of the dropping funnels were added dropwise over 2 hours, keeping the temperature at 77-85 ° C. . The contents of the reaction vessel were then heated again for 15 minutes, after which the solution was cooled to room temperature (about 23 ° C). The product solution contained 22.7% solid and had an RSV (reduced viscosity viscosity) of 0.52 (1% solution in 1 M NaCl, 25 ° C).

A polymerization vessel equipped with a water jacket and with a thermometer, stirrer, cooler and three dropping funnels was charged with 504.7 g of distilled water and 25.3 S of the above-mentioned copolymer solution (5.7 µ dry copolymer). The dropping funnels were filled as follows: dropping funnel 1 with 76.1 g of the above-mentioned copolymer solution (17.3 g of dry copolymer) and 120.0 g of distilled water, 35 dropping funnel 2 with 230.0 g of styrene and dropping funnel 3 with 5 1 g of ammonium persulfate in 120 g of distilled water.

The contents of the reaction vessel were stirred and heated to 79 ° C.

7909239 -30- 21083 / Vk / jl

The contents of the dropping funnel were added dropwise simultaneously. The contents of dropping funnel 1 and 2 were added over 4 hours. The contents of dropping funnel 3 were added over a period of 4 hours and 5 minutes. The temperature of the reaction vessel was kept at 79-87 ° C during the additions. The product was cooled to room temperature and the pH was changed from 2.1 to 8.0 with 25% sodium hydroxide solution. The product was filtered through a 100 mesh (150 μπι) sieve. The product was a white latex with 25.5% solids and an average particle size of 0.47 µm (Loebel method, Official Digest, 200, Feb. 1959).

Example XXXII

A polymerization vessel equipped with a water jacket and with a thermometer, feeder, cooler and two dropping funnels was charged with 200 g of distilled water. The dropping funnels were filled as follows: 15 dropping funnel No. 1 with 67 g of acrylamide (94 mol) and 33 g of 3-methacryloyloxy-2-hydroxypropyl trimethyl ammonium chloride (0.14 mol) in 200 g of distilled water and dropping funnel 2 with 2.5 g of ammonium persulfate in 100 g of distilled water.

The contents of the polymerization vessel were heated to 80 ° e and the contents of the dropping funnels were added dropwise over a period of 2 hours and 25 minutes keeping the temperature at 80-84 ° C. After this, the contents were further heated for 15 minutes after which the solution was cooled to room temperature (about 23 ° C).

The product solution contained 21.3% solids and had an RSV (reduced specific viscosity) value of 0.46 (1% solution in 1 M NaCl, 25 ° C).

A polymerization vessel equipped with a water jacket and with a thermometer, stirrer, cooler and three dropping funnels. filled with 30 503 g of distilled water and 27 g of the above copolymer solution (5.8 g of dry copolymer). The dropping funnels were filled as follows: dropping funnel 1 with 81 g of the above-mentioned copolymer solution (f7.3 g of dry copolymer) and 120 g of distilled water, 35 dropping funnel 2 with 230 g of styrene and dropping funnel 3 with 5.1 g of ammonium persulfate in 120 g distilled water.

The contents of the polymerization vessel were stirred and heated to 7909239 -31-21083 / Vk / µl 77 ° C. The contents of the dropping funnels were added dropwise simultaneously. The contents of the dropping funnels 1 Qi 2 were added over a period of 4 hours. The contents of dropping funnel 3 were added over a period of 4 hours and 15 minutes. The temperature of the polymerization vessel was kept at 77-88 ° C during the additions.

The product was cooled to room temperature and the pH was changed from 1.9 to 6.5 with 25% sodium hydroxide solution. The product was filtered over a 100 mesh (150 pn) sieve. The product was a white latex with 25.5 t solid and an average particle size of 0.8 ^ (Loebel method, Official Digest, 200, Feb. 1959). Example XXXIII

The compositions of Examples XXIX-XXXII were further investigated as a filler for paper. Paper for paper towels or the like (handsheet) was prepared using a Noble & Wood handsheet -15 machine. The pulp consisted of a 50:50 blend of bleached hard wood: bleached soft wood pulp crushed to a Canadiai Standard Freeness of 500. The paper was prepared at a pH of 4.5 (sulfuric acid, no alum). The latex was tested at a level of 4% and 8% (dry basis). Unfilled paper was used as blank. The results of these 20 tests are summarized in Table K.

Table K.

base o dry weight opaque-clear-pull "Mullen% * (lb / 3000 nity * ny ** strength burst" filler (¾) sq.ft) (%) (%) (lb./in.) (psi ) 25 none 39.6 73.4 80.2 19.2 31.0 example XXIX (4) 40.4 78.4 81.6 19.4 32.5 example XXIX (8) 41.0 83.0 82 , 6 18.1 30.6 Example XXX (4) 42.1 79.2 83.6 21.9 33.5 Example XXX (8) 40.9 83.0 85.5 21.5 32.9 30 Example XXXI (4) 41.6 78.3 82.8 19.6 30.7 Example XXXI (8) 41.5 81.4 83.1 21.0 33.3 Example XXXIK4) 39.3 75.3 79. 8 20.6 31.0 Example XXXII (8) 41.6 80.8 83.6 21.5 31.4

Notes * an opacity measured according to Tappi-Standard T-425 (Diano 35 Q-tester) average of four tests ** brightness measured according to Tappi Standard T-452 (D.iano brightness meter) average of four tests average of eight tests.

7909239 —32— 21083 / Vk / yl

The new organic pigments of the invention can be used alone or in combination with other organic pigments or inorganic pigments or both as a filler and paper coating.

- CONCLUSIONS - 7909239

Claims (7)

1. Graft copolymer particles consisting essentially of a free-radical catalyzed graft copolymerization product of 5 1) at least one ethylenically unsaturated monomer and 2. a water-soluble cationic prepolymer having an RSV value of from about 0.1 to about 2, 5 (1 M NaCl, 1,, 25 ° C), characterized in that the prepolymer unit of the graft copolymer particles is present on the surface of the particles, the monomer 1) being selected from a group consisting of methyl chloroerylate, ethyl t-chloro acrylate, methyl methacrylate, isopropyl methacrylate, phenyl methacrylate, vinyl chloride, acrylonitrile, methacryl nitrile, and monomers of formula 7, indicated on the formula sheet, where R is hydrogen or methyl, Y is methyl or chlorine and n 0, 1, 2 or 3, and 15 is the prepolymer 2) the addition polymerization product is from a) about 5 mol% to 100 mol% of at least one cationic monomer selected from the group consisting of compounds of formula 1, indicated on the formula sheet, where R ^ is hydrogen or methyl, R2 is hydrogen or an alkyl group of 1-4 carbon atoms, R ^ is hydrogen, 20 OH ------ \ an alkyl group with 1-4 carbon atoms, -CHgCHC ^ Y, where Y is hydrcxyl 0 or halogen, -CHgCHCHg and - (CHgCHgO ^ H, where n is an integer of 1 or more and X ”is an anion, compounds of formula 2, indicated on the formula sheet, where R 1 is hydrogen or an alkyl group of 1-4 carbon at cm and, R 2 is hydrogen, alkyl or substituted alkyl, and R 1 and X are the same as defined in formula 1, compounds of formula 3, indicated on the formula sheet, wherein R 1, R 2, R ^ and X "have the same meaning as stated for formula 1, compounds of formula 4, indicated on the formula sheet wherein R 1, R 2 and X "have the same * meaning as indicated for 1 formula 1, 35 compounds of formula 5 indicated on the formula sheet, wherein R 1, R 2 and R 1 and X" have the same meaning as indicated for formula 1 and n is an integer with the value 1, 2 or 3 and compounds of formula 6, indicated on the formula sheet, 7909239 τ * --34-21083 / Vk / jl where R ^, Rg, R ^ and X ”have the same meaning as indicated for formula 1, b) about 95 mol% to 0 mol% of at least one ethylene-like and saturated Cl non-ionic monomer selected from the group consisting of 5 N-vinyl pyrrolidone, ethylene-like unsaturated monomers with an amide function and ethylene-like unsaturated monomers with a hydroxyl function, the amount of the prepolymer (2) used to prepare the graft copolymer particles is between about 1 wt. divide to about 25 parts by weight for every 100 wt. parts used monomer 1). Graft copolymer particles according to claim 1, characterized in that monomer 1) is s-styrene and a) of prepolymer 2) is the monomer of formula 1 and b) of prepolymer 2) is a monoethylene-like unsaturated amide, the amount of prepolymer 2) used to prepare the graft copolymer particles is between 2 and 10 wt. parts on every 100 wt. parts of monomer 1) as used, and the RSV value of the prepolymer is between 0.1 and 1.0. Graft copolymer particles according to claim 1, characterized in that the monomer is Dstyrene and a) of prepolymer 2) is the monomer of formula 2 and b) of prepolymer 2) is a monoethylenic unsaturated amide in which the amount of prepolymer 2) used for the preparation of the graft copolymer particles lies between 2 wt. parts up to 10 wt. parts on every 100 wt. parts of monomer 1) when used and the RSV value of the prepolymer is between about 0.1 and 1.0. Graft copolymer particles according to claim 1, characterized in that monomer 1) is styrene and a) of prepolymer 2) is the monomer of formula 3 and b) of prepolymer 2) is a "monoethylene-like unsaturated" amide in which the amount of prepolymer 2) used in the preparation of the graft copolymer particles is between 2 parts to 10 wt. divide 30 by 100 wt. parts of monomer. 1) as used and the RSV value of the pre-polymer is 0.1 to 1.0. Graft copolymer particles according to claim 1, characterized in that monomer 1) is styrene and a) is of prepolymer 2) is the monomer of formula 4 and b) is of prepolymer 2) is a monoethylene-like unsaturated amide, the amount of prepolymer 2) is used for the preparation of the graft copolymer particles comprised between 2 and 10 wt. parts on every 100 wt. parts of monomer 1) as used and the RSV value of the prepolymer is 0.1 to 1.0. 7909239 -35- 21083 / Vk / jl 6 OH R3 il ^ V; 4; ch2 ch, ch, II J ~ m *, II2 II2 Graft copolymer particles according to claim 1, characterized in that monomer 1) is styrene and a) of prepolymer 2) is the monomer of formula 5 and b) of prepolymer 2) is a raonoethylene-like unsaturated amide, the amount of prepolymer 2 used for the preparation of the graft cc polymer particles is between 2 wt. parts and 10 wt. parts on every 100 wt. parts of monomer 1) as used and the RSV value of the prepolymer is between 0.1 and 1.0. Graft copolymer particles according to claim 1, characterized in that the monomer 1) is styrene and a) of prepolymer 2) is the monomer of formula 6 and b) of prepolymer 2) is a monoethylene-like unsaturated amide, wherein the amount of prepolymer 2) used for the preparation of the graft copolymer particles is between 2 and 10 wt. parts on every 100 wt. parts of monomer 1) as used, and the RSV value of the prepolymer is 0.1 to 1.0. Graft copolymer particles according to claims 2-7, characterized in that b) is the monoethylene-like unsaturated amide acrylamide. Graft copolymer particles according to claim 2, characterized in that the prepolymer 2) is prepared from 70 mol% to 98 mol% acrylamide and: - 30 mol% - 2 mol% dimethyldiallylammonium chloride. Graft copolymer particles according to claim 2, characterized in that the prepolymer 2) is prepared from 67 mol 56-98 mol% acrylamide and from 33 mol J6-2 mol% methyl diallyl ammonium chloride. Graft copolymer particles according to claim 2, characterized in that prepolymer 2) is prepared from 70 mole% J6- 98 mole% acrylamide and 25 mole% -2 mole% methyl diallyl ammonium acetate. Graft copolymer particles according to claim 2, characterized in that prepolymer 2) is prepared from 70 moles of 56-95 mols of acrylamide and from 30 moles of 5 to 5 mol% of methacryloyloxyethyl trimethyl ammonium methyl sulfate. Graft copolymer particles according to claim 3, characterized in that prepolymer 2) is prepared from 82 mole 56-90 mole% acrylamide and from 13 mole% - 10 mole 56 dimethyl iallyl ammonium chloride. Graft copolymer particles according to claim 3, characterized in that prepolymer 2) is prepared from 67 mol 56-89 mol acrylamide and from 33 mol 56-11 mol 56 methyl diallyl ammonium chloride. Graft copolymer particles according to claim 3, characterized in that prepolymer 2) is prepared from 82 mol 56-91 mol% acrylamide and from 18 mol 56-9 mol% methyl diallyl ammonium acetate. Graft copolymer particles according to claim 2, characterized in that 7909239 -36-21083 / Vk / µl prepolymer 2) is prepared from 70 moles $ -88 moles acrylamide and 30 moles -12 moles methacryloyloxyethyl trimethyl ammonium methyl sulfate. Graft copolymer particles according to claims 1-7, characterized in that the prepolymer unit of the particles is chemically linked to a cellulose reactive group. Graft copolymer particles according to claims 1-7, characterized in that the monoethylene-like unsaturated amide is acrylamide and the prepolymer unit of the particles is chemically bonded to a cellulose reactive group. Graft copolymer particles according to claims 9-16, characterized in that the prepolymer unit of the particles is chemically bound to a cellulose reactive group. Graft copolymer particles according to claims 9-16, characterized in that the prepolymer unit of the particles is chemically bound to an aldehyde group. 21. A method of preparing paper using an opacifying agent to effect opacity in the final paper product, by coating or internal addition to the paper pulp, characterized in that at least part of the opacifying agent consists of the substantially water insoluble graft copolymer in particulate form as described in claims 1-7. 22. A method according to claim 21, characterized in that at least part of the opacifying agent is the substantially water-insoluble particulate copolymer as described in claims 1-7, wherein the monoethylenic unsaturated amide is acrylamide. A method according to claim 21, characterized in that at least part of the opacifying agent is the water-insoluble graft copolymer in particulate form as described in claims 9-16. A method according to claim 21, characterized in that at least part of the opacifying agent is the water-insoluble graft copolymer in particulate form as described in claims 1-7, wherein the prepolymer unit of the particles is chemically bonded to a cellulose Lose-reactive group. Process according to claim 21, characterized in that at least a part of the opacifying agent consists of substantially insoluble graft copolymer particles 1 as described in claims 9-16, wherein the prepolymer unit of the particles is chemically bound to 7909239 - 37-21083 / Vk / µl an aldehyde group. 26. Process for preparing a latex from graft copolymer particles, characterized in that a graft copolymerization is carried out in an aqueous medium and in the presence of a free radical initiator of 1) at least one ethylene agent unsaturated monomer and 2) a water-soluble cationic prepolymer with an RSV value of about 0.1 to 2.5 (1 M NaCl, 1%, 25 ° C), the monomer 1) being selected from a group consisting of methyl-B (chloroerylate, ethyl Λ-chloroacrylate, methyl methacrylate, isopropyl-10 methacrylate, phenyl methacrylate, vinyl chloride, acrylonitrile, methacryl-onitrile and monomers of formula 7, indicated on the formula sheet where R is hydrogen or methyl, Y is methyl or chlorine and n is 0,1, 2 or 3 and the prepolymer 2) the addition polymerization product is from 15 a) about 5 mol% to 100 mol% of at least one cationic monomer selected from the group consisting of compounds of formula 1, indicated on the formula sheet, where fis hydrogen or methyl, R2 is hydrogen or an alkyl group with 1-4 carbon atoms, R ^ is hydrogen, OH / 20 is an alkyl group with 1-4 carbon atoms, -C ^ CHCHgY where Y is hydroxyl 0 or halogen -CH ^ CHC ^, and - (CH 2 CH 2 O) nH where n is an integer of 1 or more and X ”is an anion, compounds of formula 2, indicated on the formula sheet, where R 1 is hydrogen or an alkyl group of 1-4 carbon atoms, R 2 is hydrogen alkyl or substituted alkyl and R 1 and X 1 have the same meaning as indicated for formula 1, compounds of formula 3 indicated on the formula sheet, wherein R 1, R 2, R 1 and X 1 have the same meaning as indicated for Formula 1, compounds of formula 4, indicated on the formula sheet, where R 1, R 4 and X- have the same meaning as indicated for formula 1, compounds of formula 5, indicated on the formula sheet, where R 1, R 2, R ^ and X “have the same meaning as indicated for formula 1 and n is an integer with the waa rd 1, 2 or 3 and compounds of formula 6, indicated on the formula sheet, wherein R 1, R 2, R 1 and X "have the same meaning as indicated for 7909239 -38 - 21083 / Vk / jl 4 formula 1 and b) about 95 mole% to 0 mole% of at least one ethane-like unsaturated nonionic monomer selected from a group consisting of N-vinylpyrrolidone, ethane-like unsaturated monomers having an amide-5 function and ethylene-like unsaturated monomers having a hydroxyl function, the amount of prepolymer 2 ) used for the preparation of the graft copolymer particles is between 1-25 wt. parts on every 100 wt. parts of the monomer used 1). 27. Process according to claim 26, characterized in that the monomer 1) is styrene, and a) of the prepolymer 2) is a monomer of formula 1, indicated on the formula sheet, and b) of the prepolymer 2) is a monoethylene-like, unsaturated amide, the amount of prepolymer 2) being between 2 wt. parts and 10 wt. parts on every 100 wt. parts of monomer 1) as used, and the RSV value of the pre-15 polymer is 0.1 to 1.0. * 28. Process according to claim 26, characterized in that the monomer 1) is styrene and a) of the prepolymer 2) is the monomer of formula 2 indicated on the formula sheet and b) of the prepolymer 2) is a monoethylene-like · unsaturated amide, the amount of prepolymer 2) being between 2 parts by weight and 10 wt. parts on every 100 wt. parts of monomer 1) as used and the RSV value of the prepolymer is 0.1-1.0. 29. Process according to claim 26, characterized in that the monomer 1) is styrene and a) of the prepolymer 2) is the monomer of formula 3 and b) of prepolymer 2) is a monoethylene-like unsaturated amide, the amount of prepolymer 2) if used it is between 2 wt. parts and 30 parts by weight for every 100 parts by weight. parts of monomer 1) as used and the RSV value of the prepolymer is 0.1-1.0. 30. Process according to claim 26, characterized in that the monomer 1) is styrene and a) of the prepolymer 2) is the monomer of formula 4 indicated on the formula sheet and b) of prepolymer 2) is a monoethylene-like unsaturated amide, the amount of prepolymer 2) used being between 2 wt. parts and 10 wt. parts on every 100 wt. parts of monomer 1) as used and the RSV value of the pre-35 polymer is 0.1-1.0. A process according to claim 26, characterized in that monomer 1) is styrene and a) of the prepolymer 2) is the monomer of formula 5 indicated on the formula sheet and b) of the prepolymer 2) is a 7909239 -39- 21083 / Vk / µl monoethylene-like unsaturated amide, the amount of prepolymer 2) as used being between 2 wt. parts and 10 wt. parts on every 100 wt. parts of monomer 1) as used and the RSV value of the prepolymer is 0.1-1.0. A process according to claim 26, characterized in that the monomer 1) is styrene and a) of the prepolymer 2) is the monomer of formula 6 indicated on the formula sheet and b) of the prepolymer 2) is a monoethylene-like unsaturated amide wherein the amount of prepolymer 2) used is between about 2 and 10 wt. divide at Ί0 every 100 wt. parts of monomer 1) as used and the RSV value of the prepolymer is 0.1-1.0. 33 * Process according to claims 27-32, characterized in that b) is the monoethylenically unsaturated amide acrylamide. 3¾. Process according to claim 26, characterized in that, before the graft copolymerization is effected, the prepolymer is reacted with a compound which gives the prepolymer cellulose reactive groups. 35. A method according to claim 26, characterized in that the graft copolymer particles are then reacted with a compound which give cellulose reactive groups on the surface of the particles. 36. Paper obtained by a method as described in claims 21-25. 37. Graft copolymer particles, substantially insoluble in water, as specified in claim 1, characterized in that in combination with monomer 1) a polyethylene unsaturated monomer is used in an amount at least sufficient to crosslinked grafts. copolymer particles, wherein the unsaturated monomer is selected from the group consisting of divinylbenzene, diallylphthalate, ethylene glycol dimethyl methacrylate, 1,3-butylene glycol dimethacrylate, 1,6, hexanediol dimethacrylate, polyethylene glycol dimethyl acrylethyl dimethyl benzyl dimethyl benzyl dimethyl acrylate trimethylolpropane trimethacrylate, pentaerythritol tetraacrylate and mixtures thereof. 38. Graft copolymer particles which are substantially insoluble in water, as described in claims 2-7, characterized in that a polyethylene-like unsaturated monomer is used in an amount at least sufficient to obtain cross-linked 7909239 in combination with styrene. -40-21083 / Vk / µl graft copolymer particles, wherein the unsaturated inomer is selected from a group consisting of divinylbenzene, diallylphthalate, ethylene glycol dimethacrylate, 1,3-butylene glycol dimethacrylate, 1,6-hexanediol dimethyl acrylate, dimethyl propylene glycol Crystall, trivinyl benzene, divinyl naphthalene, diallyl maleate, diallyl furarate, trimethylol propane trimethacrylate, pentaerythrit tetracrylate, and mixtures thereof. * 7909239 Formula sheet 21083 / Vk / jl CH «OH-? 1/2 · I2 II I + / - p -C C-R-i CH -ccooc2h4n-b2 X 81 | [R, CH2 ch2 X 3 1. <+ / R. I 2 p * '/ 3. ^ R, f2 I —C * CH-X / Hv ^ / \ ^ N + * 3. R2 I 4. * 2 R3 R1 r2 I + /. CH2 * CCONH (CH2) nN — R2 X \ 3 5. R1 Ro I + / CH- * CCOOCH-CHCH.N ~ R, X & L · | & i 7. R -c C-R, 1 | | 1 ch2 CH2 8. 79 0 92 3 9 r2