CA1134091A - Organic pigments for using as paper fillers - Google Patents

Abstract

ABSTRACT OF THE DISCLOSURE
Disclosed are novel organic pigments adapted partic-ularly for use as fillers for paper. The organic pigments are finally divided particles obtained by graft copolymer-izing an ethylenically unsaturated monomer, such as styrene, onto a water-soluble cationic prepolymer in an aqueous solution and in the presence of a free-radical polymerization initiator.

Description

This invention relates to novel organic pigments adapted particularly for use as paper fillers.
Paper is often filled with mineral fillers such as clay, calcium carbonate or titanium dioxide. The function of a minera] filler is to increase the opaclty of the paper and prevent "showthroush"; low opacity leads to page-to-page show-through in printed matter such as books, mag-azines and newspapers. While the mineral fillers perform ; this function very well at relatively low cost, they also ; 10 have disadvantages. First, they reduce paper strength sub-stantially. This can cause problems ln later use, but more importantly, low sheet strength can make it necessary to run the paper machine at slower speeds. The second disad-vantage is that the mineral fillers have relatively high densities (sp. gr. 2.5-4.0) and thus increase the weight of filled paper. This is becoming more of a problem as --the rising cost of mailing printed material, such as mag-azines, is increasing the demand for light-weight paper.
Thus, there is a need in the paper industry for a low den-sity opacifier for paper that will not adversely affect the strength of the paper.
The use of latex particles as lightweight fillers for - paper is known in the art. Polystyrene latexes are commer-cially available for this application. Like minera] fill-ers, these polystyrene latexes consist of anionic particles that require cationic retention aids for good retention on anionic pulp fibers. In addition, polystyrene latex fill-ers decrease the strength of filled paper, although less than mineral fillers do.
Also, small particles of urea formaldehyde resin have been used as paper fillers. It is reported that these ~3'~

particles are lightweight and, when used as paper fillers, improve opacity, brightness, smoothness and bulk of the paper; however, they have an adverse effect on paper strength, although ~his effect is reported to be less than that of the mineral fillers.
Disclosed in U.S. patent 3,824,11~ are microcapsules ha~ing a solid polymeric shell and a solid, non-tacky poly-meric core which is grafted to the polymeric shell. The microcapsules may be coated onto cellulosic substrates or incorporated into such substrates and subsequently fused to provide cellulosic substrates having a polymeric film bonded thereto and increased strength, respectively. This patent states at col. 3, lines 29-40 that the polymer-containing microcapsules may be formed having an average particle diameter of between about 0.5 and about 1.0 micron. It is stated also that the particles are capable of imparting high opacity to surface coatings of various substrates. It is also stated that the microcaps~les may be interspersed with cellulose fibers and formed into a web of such fibers and that the polymeric microcapsules act as non-abrasive, opacifying agents and impart a high opacity to the cellulose substrate ultimately formed.
An object of this invention is to provide organic p;gments that can be used as fillers for lightweight paper and that provide opacity, brightness and smoothness without adversely affecting paper strength. A further object of this in~ention is to provide organic pigments that are selE~retainin~ during the paper making process; that is, the organic pigments are well retained on pulp fibers with-out the use of conventional retention aids.
In accordance with this invention, there are providedgraft copolymer particles, suitable for use as organic pig-ments and particularly as paper ~illers, and consisting essentially of the free radical catalyzed graft copolymer-ization product of tl) at least one ethylenically unsatur-ated monomer and (2) a water-soluble cationic prepolymer having an RSV of about 0.1 to about 2.5 (lM NaCl, 1%, 25C.), the prepolymer moiety of the graft copolymer ~3~

particles being present on the surface of the particles, said monomer (~) being selected from the group consisting of methyl alpha-chloroacrylate, ethyl alpha-chloroacryla~e, methyl methacrylate, isopropyl methacrylate, phenyl methacrylate, vinyl chloride, acrylonitrile, methacrylonitrile, and monomers having the formula - C=CH2 wherein R is hydrogen or methyl, ~ (Y)n Y is methyl or chlorine, and n is 0, 1, 2, or 3, and said prepolymer (2) being the addition polymeri~ation product of (i) about 5 mole per cent to 100 mole per cent of at least one cationic monomer selected from the group consisting of Rll R2 (I) CH2=CCOOC2H~N\ R2 X

wherein Rl is hydrogen or methyl, R2 is hydrogen or a Cl-C~ alkyl, R3 is : fH
hydrogen, a Cl-C4 alkyl, -CH~CHCH2Y
O
where Y is hydroxyl or halogen, -CH2CHCH2, and ~-CH2CH2O)nH where n is an integer 1 or more and X is an anion, CH CH

2 1l 2 R -C C-R
C ~ CH2 X

~L3~

wherein Rl is hydrogen or a C1-C4 alkyl, R2 is hydrogen, a].kyl or subst;tuted alkyl, and R3 and X are as defined in formula (I), R
l~C=CH2 (III) ~ X
fH2 : wherein Rl, R2, R3 and X are as defined in formula (I), (IV) ~ clcH2 X
N~

wherein Rl, R3 and X are as defined in formula (I), Rl +~R2 (V) CH2=CcONH (CH2) nN\ R2 X

wherein Rl, R2, R3 and X are as defined in ~ormula (I), and n is an integer 1, 2 or 3 and (VI) 2 2J 2 \ 2 X

~.~ 3~

wherein Rl, R2, R3 and X are as defined in formula (I), and (ii) from abou~ 95 mole per cent to 0 mole per cent of at least one ethylenically unsatur-ated nonionic monomer selected from the group consisting of N-vinyl pyrrolidone, ; ethylenically unsaturated monomers having amide functionality, and e~hylenically un-saturated monomers having hydroxyl functionality, the amount of prepolymer (2) employed in preparing the graft copolymer particles being from about 1 part to about 25 parts by weight for each 100 parts by weight of monomer (1) employed. Substantially all the cationic prepolymer moiety of the graft copolymer particles is on the surface of the resulting particles.
When the graft copolymer particles of this invention are suspended in water in the presence of cellulosic pulp fibers, they are attracted to the anionic sites on the sur-face of the fibers and adhere to the pulp fibers. During the paper making process, which comprises drainage of water from a slurry of pulp fibers, the cationic particles re-main with the pulp fibers and are thus well retained in the paper.
Graft copolymer particles prepared using water-; soluble prepolymers containing an optimum level of cationic functionality are self-retained during the papermaking process; that is, when these particles are slurried with pulp fibers prior to sheet formation, the particles adhere strongly to the anionic pulp fibers and very little, if any, are lost when the water is filtered off during the paper making process. Thus, no retention aid is required to keep the particles with the pulp fibers. However, known retention aids can be used in the paper making process, if ~esired. In addition, paper filled with ~raft copolymer particles prepared according to this inventio~ has strength properties usually equivalent to and sometimes better than unfilled paper of the same weight. Papers filled with min-eral pigments, such as clay or ti~anium dioxide, have sub-stantially lower strength properties than the corresponding unfilled paper.
The monomers used to prepare these particles are such that they will graft polymerize onto the cationic water-soluble prepolymer to form a water-insoluble graft copoly-mer. It is the insolubility of the graft copolymer that leads to the formation of discrete, essentially spherical particles suspended in water. The initial function of the water-soluble cationic prepolymer is to stabilize the sus-pension and prevent coagulation of the individual particles.
After ini~ial graft copolymerization is effected some homo-polymerization of the monomer may occur inside the par-ticles. Essentially stable latexes of the qraft copolymerparticles are prepared in accordance with this invention without requiring the presence of an additional stabili~er.
There are two main requirments for the graft copolymer particles prepared in accordance with this invention. They must ~1) be water-insoluble and (2) have a high enough melting or soEtening point that they will not be deformed to any substantial degree under the conditions of heat or pressure or both to which they wil:L be subjected in use.
Use as fillers for paper requires that the particles remain discrete and essentially spherical during web formation, drying and calendering. Preferably, the graft copolymer will have a second order transition temperature (glass transition temperature, Tg) of about 75C. or greater.
All the graft copolymers prepared by the working examples that follow have a Tg greater than 75C.
Any monomer that will graft copolymeri~e with the water-soluble cationic prepolymers, hereinafter described, to provide graft copolymer particles meeting the above re-quirements can be employed in this invention. Suitable monomers are monoethylenically unsaturated monomers such, for example, as acrylic esters such as methyl ~-chloro-acrylate and ethyl ~-chloroacrylate; methacrylic esters such as methyl methacrylate, isopropyl methacrylate and 7_ phenyl methacrylate; monomers having the formula ~ ~ (Y)n where R is hydrogen or methyl, Y is methyl or chlorine and n is 0, 1, 2 or 3. Examples of such monomers are styrene, a -methyl styrene, monochlorostyrene, dichlorostyrene, trichlorostyrene, monomethylstyrene, dimethylstyrene and trimethylstyrene. Other suitable monomers are vinyl chloride, acrylonitrile and methacrylonitrlle.
Mixtures of two or more monoethylenically unsaturated monomers can be used in carrying out this invention pro-vided the resulting graft copolymer particles are water-insoluble and have a Tg of about 75C. or greater.
Also polyethylenically unsaturated monomers, such as di-vinylbenzene, can be used in admixture with monoethylenic-ally unsaturated monomers to provide crosslinked graft co-polymer particles. Of the above listed monoethylenically unsaturated monomers, styrene, vinyl chloride, acryloni-trile and methyl methacrylate are preferred.
The water-soluble cationic prepolymer can be any of a variety of polymers. The main criterion is that it provide the optimum cationic charge for good retention of the re-sulting graft copolymer particles in paper. For example, in a latex prepared using about 10~ prepolymer based on the weight of the monomer used, opacity is hlghest when the mole percent of the cationic monomer moiety of the water-soluble prepoLymer is in the range of about 5 to 50, with the optimum range being from about 10 to about 30 mole per-cent. These ranges are, of course, dependent on the level of water-soluble cationic prepolymer used to prepare the latex. Thus when about 5~ water-soluble prepolymer based on monomer is used, the range would be about 10 to about 100 mole percent cationic monome~ moiety with the optimum range being from about 20 to about 60 mole percent.
Similar corrections can be made when other levels oE

~3/~

wa~er-soluble ~olymer are used and are within the skill of the art.
The cationic water-soluble prepolymers that are par-ticularly suitable for use in this invention are addition-type polymers prepared from ethylenically unsaturatedcationic monomers having the formulas (I), (II), (III), (IV), (V) and (VI) below.

(I) CH2=Ccooc2H4N\ 2 In formula (I), Rl is hydrogen or methyl; R2 is hydro-gen or a Cl-C4 alkyl such as methyl, ethyl, propyl, or OH
butyl; R3 is hydrogen, a Cl-C~ alkyl, -CH2CHCH2Y
where Y is hydroxyl or halogen such as chlorine and / \
bromine, -CH2CH~H2, and (CH2CH20)nH where n is an integer l or more, preferably 1 through 20; and X is an anion such as Cl , Br , CH30S03 and CH3COO .
Monomers of formula (I) are quaternary ammonium salts and acid salts of amino acrylates such as dimethylaminoethyl~
acrylate, diethylaminoethylacrylate, dimethylaminoethyl-methacrylate, and diethylaminoethylmethacrylate. Specific quaternary salt monomers having the formula (I) are metha-cryloyloxyethyltrimethylammonium methyl sulfate and metha-cryloyloxyethyltrimethylammonium chlorideO Speci~ic acid salt monomers having the formula (I) are methacryloyloxy-ethyldimethylammonium chloride and methacryloyloxyethyldi-methylammonium acetate.
CH CH

( I I ) Rl-f C-Rl +~ X
¦ \R

~3fl~
g In formula (II), Rl is hydrogen or a Cl-C4 alkyl.
R2 i5 hydrogen, alkyl or substituted a]kyl. Typical alkyl groups, which R2 can be, contain from 1 through 18 carbon atoms, preferably from 1 through 6, and include methyl, ethyl, propyl, isopropyl, t-butyl, hexyl, octyl, decyl, dodecyl, tetradecyl, and octadecyl. R2 can also be a substituted alkyl, suitable substituents being any sub-stituent that will not interfere with polymerization through a vinyl double bond. Typically the substituents can be carboxylate, cyano, ether, amino ~primary, secondary or tertiary), amide, hydrazide and hydroxyl. R3 and X
are as defined in formula (I). The formula (II) monomers are quaternary ammonium salts and acid salts of a diallyl~
amine having the formula CH2 C~2 Il 11 Rl-l f-R
C ~ CH~

where Rl and R2 are as above defined. Specific exam-ples of quaternary ammonium salt monomers having formula tII) are dimethyldiallylammonium chloride and dimethyldi-allylammonium bromide. Specific examples o~ acid salt monomers having formula (II~ are methyldiallylammonium acetate, diallylammonium chloride, N-methyldiallylammonium bromide, 2,2'-dimethyl-N-methyldiallylammonium chloride, N-ethyldiallylammonium bromide, N-isopropyldlallylammonium chloride, N-n-butyldiallylammonium bromide, N-tert-butyl-diallylammonium chloride, N-n-hexyldiallylammonium chlor-ide, N-octadecyldiallylammonium chloride, N-acetamidodi-allylammonium chloride, N-cyanomethyldiallylammonium chloride, N-~-propionamidodiallylammonium bromide, N-acetic ethyl ester substituted diallylammonium chloride, N-ethylmethylether substituted diallylammonium bromide, N-~ethylaminediallylammonium chloride, N-hydroxyethyldiallyl-ammonium bromide and N-aceto-hydrazide substituted - ~3~
~10-diallylammonium chloride.
R~
C=CH2 (III) ~ X

N+
R/ ¦~R

In formula (III), Rl, R2, R3 and X are as defined in formula (I). Specific examples of monomers of formula (III) are vinylbenzyltrimethylammonium chloride and vinyl-benzyltrimethylammonium bromide.

(IV) ~ ~ C=CH2 X
N-~

:In formul.a (IV), Rl, R3 and X are as defined in formula (I). Specific examples of monomers of formula (IV) are 2-vinylpyridinium chloride and 2-vinylpyridinium bromide.

: 7 / 2 (V) CH2=CCONH (CH2) nN--R2 X

In formula ~V), Rl, R2, R3 and X are as defined in formula (I), and n is an integer 1, 2 or 3. A specific 1~ example of a monomer of formula (V) is methacrylamido-propy~dimethylammonium chloride.
IRl +/ 2 (VI) CH2-CCOOcH2lHcH2N\ R2 X
.~ OH R3 In formula (VI), Rl, R2, R3 and X are as defined in formula (I). A specific example of a monomer of ~l3~

~ormula (VI) is 3-methacryloyloxy-2-hydroxypropyldimethyl-ammonium chloride~
The water-soluble cationic prepolymer used in this invention can also be a naturally occurring polymer such as casein or a derivative of a naturally occurring polymer such as chitosan.
As set forth above, there is an optimum level of cat-ionic charge on the polymer particle required for good re-tention in paper. The optimum charge can be achie~ed with a cationic homopolymer by varying the amount of homopolymer used to prepare the graft copolymer latex. It is preferred however to adjust the cationic charge by using a copolymer of at least one cationic monomer and at least one nonionic unsaturated monomer capable of addition-type polymeriza-tion. Examples of nonionic monomers are monoethylenicallyunsaturated amide monomers such as acrylamide; methacryl-amide; N-acetamidoacrylamide; N-acetamidomethacrylamide;
N-methylolacrylamide; diacetoneacrylamide; diacetonemetha-crylamide; N,N-dimethylacrylamid~; and N-methylacrylamide.
Other suitable nonionic monomers are vinyl acetate; 2-hydroxyethylacrylate; 2-hydroxyethylmethacrylate; and N-vinylpyrrolidone. Copolymers of vinyl acetate are sub-sequently hydrolyzed to replace essentially all the acetate groups with hydroxyl groups.
The water-soluble cationic prepolymers used in this invention can be (A) homopolymers o~ the cationic monomers shown in formulas (I) through (VI); (B) copolymers of any two or more o~ the monomers shown in formulas (I) through (VI); and (C) copolymers o at least one of the monomers shown in formulas (I) through (VI) and at least one other ethylenically unsaturated monomer, preferably a nonionic monomer. Thus, the preferred water-soluble cationic pre-; polymers will consist essentially of from about 5 mole percent to 100 mole percent of at least one monomer shown in formulas (I) through (~I) and from ~bout 95 mole per-cent to 0 mole percent of at least one other ethylenically unsaturated nonionic monomer.
Highly satisfactory water-soluble cationic prepolymers for use in preparing the graft copolymer par-ticles of this invention are (1) the prepolymers prepared from about 70 mole % to about 98 mole %, preferably from about 82 mole % to about 90 mole ~, acrylamide and from about 30 mole ~ to about 2 mole ~, preferably from about 18 mole % to about 10 mole ~ dimethyldiallylammonium chloride;
(2) the prepolymers prepared from about 67 mole % to about 98 mole %, preferably from about 67 mole % to about 89 mole ~, acrylamide and from about 33 mole ~ to about 2 mole %, preferably from about 33 mole ~ to about 11 mole %, methyl-diallylammonium chloride (3) the prepolymers prepared from about 70 mole % to about 98 mole %, preferably from about 82 mole ~ to about 91 mole ~, acrylamide and from about 30 mole % to about 2 mole ~, preferably from about 18 mole %
to about 9 mole %, methyldiallylammonium acetate; and ~4) the prepolymers prepared from about 70 mole ~ to about 95 mole ~, preferably from about 70 mole ~ to about 88 mole %
acrylamide and from about 30 mole ~ to about 5 mole %, preferably from about 30 mole % to about 12 mole ~, meth-acryloyloxyethyltrimethylammonium methyl sulfate.
The water-soluble cationic prepolymers are easily and readily prepared by adding, simultaneously, the de-sired monomers, in the desired amounts, and a water-soluble ~ree-radical polymerization initiator, each in aqueous sol-ution, to a reaction vessel containing water maintained ata temperature of about 80C. to about 90C. Suitable free-radical polymerization initiators are those employed in preparing the graft copolymer particles of this inven-tion and which are set forth hereafter. The amoun~ of initiator employed will be that amount sufficient to pro-vide water-soluble cationic prepolymers having an RSV of from about 0.1 to about 2.5, preferably from about 0.1 to about 1.0, measured as a 1% solution in lM NaCl at 25C.
In some cases, it is desirable to have reactive func-tionality, that is, reactive groups on the surface of thegraft copolymer particles. The reactive groups generally increase the bonding properties of the graft copolymer ~3~

., particles. Preferred reactive groups are those that react with cellulose.
Reactive groups can be introduced into the cationic monomer prior to preparation of the prepolymer, or they can be introduced into the prepolymer after preparation there-of, or they can be introduced into the graft copolymer par-ticles after their preparation.
Cellulose reactive groups can be introduced by react-ing an epihalohydrin, such as epichlorohydrin, with poly-mers containing secondary amine functionality, or tertiaryamine functionality, or both. Reactive groups provided by epihalohydrin can be an epoxide, the halohydrin form of the epoxide, or an azetedinium group.
Reactive groups can be introduced by means of an aldehyde such as formaldehyde, glyoxal and glutaraldehyde with polymers containing amide functionality, such as those prepolymers prepared by copolymerizing a cationic monomer and acrylamide or those polymers containing secon-dary amine functionality such as in prepolymers prepared from diallylamine salts. Using dialdehydes, such as glyoxal, t~e reactive group will be an aldehyde. Using formaldehyde, the reactive group will be the N-methylol group.
The amount of functionaliziny agent employed to pro-vide reactive gro~ps on the graft copolymer particles ofthis invention will be about 0.25 mole to about 3 moles, preferably about 1 mole to about 2 moles, for each mole of amide or amine functionality.
Reaction will be carried out at a temperature of from about 20C. to about 60C. at a pH of about 8 to 10 except when formaldehyde is used as the functionalizing agent, reaction is carried out at a pH of from about 2 to 3.
The reactive groups can improve paper strength by pro-viding a means for the graft copolymer particles to react with cellulose fibers. Conventional fillers generally decrease paper strength by interfering with ~onding between cellulose fibers. By use of graft copolymer particles having cellulose reactive groups, it is possible to obtain ~3~9~:~

higher paper strength through bonding between fibers through the reactive functional groups on the particles.
~ he amount of prepolymer used in preparing the graft copolymers of this invention can vary from about 1 part to about 25 parts by weight for each lO0 parts by weight of monomex employed. The preferred range is from about 2 to about lO parts of prepolymer for each lO0 parts of monomer.
Graft copolymerization is carried out by adding mon-omer to an aqueous solution of water-soluble cationic pre-polymer in the presence of a free-radical polymerization initiator. The water-soluble prepolymer can all be present in the reaction vessel at the beginning of the run, or all or part of it can be added simultaneously with the monomer.
The initiator is usually added continuously along with the monomer. The total reaction time can vary from about one hour to about 24 hours with the preferred time being about 2 to 6 hours. Latexes prepared in accordance with this lnvention will have a solids content of from about 15% to i about 60%. Preferably the amount of water employed in pre-paring the latexes will be such as to provide latexes having a solids content of from about 25% to about 55%. In some instances, 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 prior to formation of the paper. Drying the latex to a fine powder is not usually possible when the graft copol~mer particles have reactive functionality.
The final product is a stable suspension of essenti-ally spherical graft copolymer particles in water. In accordance with this invention graft copolymer particles can be prepared that will have a particle size in the range of about 0.1 micron to about 2 microns.
A wide variety of chemical polymerization initiators can be used to prepare the latexes of this invention, with peroxy compounds being particularly useful. Preferably the ini~iator will be water soluble.
Suitable water-soluble initiators include those activated by heat, such as sodium persulfate and ammonium persu]fate. Polymerizations carried out with these initiat-ors are generally run at temperatures of 70-95C. Other water-soluble initiators that are suitable include the so-called redox initiator systems such as ammonium persulfate-sodium bisulfite-ferrous ion and t-butyl hydroperoxide-sodium formaldehyde sulfoxylate. Redox initiators are acti-vated at relatively low temperatures, and polymerizations employing these systems can be carried out at temperatures from about 20C. to 80C. The amount of initiator em-ployed is within the skill of the art~ Usually about 0.1part to about 5 parts by weight of initiator will be em-ployed for each 100 parts by weight of monomer used. The following examples illustrate the invention.

A water-~acketed resin kettle equipped with a ther-mometer, a stirrer, a condenser and three addition funnels was charged with 87.0 g. of distilled water. The funnels were charged with: (1) 71.25 g. acrylamide (1.0 mole) in 166.0 g. distilled water, (2) 3.75 g. dimethyldiallylammon-ium chloride (DMDAAC, 0.023 mole) in 8.75 g. distilled water, and (3) 1.88 g. ammonium persulfate (0.008 mole) in 35.6 9. distilled water. The kettle contents were heated to 85-89C., and the contents of the three funnels were added, dropwise, over a period of three hours. After heat-ing for an additional fifteen minutes, the solution wascooled to room temperature (about 23 C.). The product solution contained 21.9% solids and had an RSV, reduced specific viscosity, of 0.32 (1~ solution in lM NaCl at 25C.).
A water-jacketed resin kettle fitted with a ther-mometer, a stirrer, a condenser and three addition funnels was charged with 493.0 9. of distilled water and 54.4 g. of a 10% solids solution of the above copolymer (5.44 g. dry copolymer). The funnels were charged with: (1) 164.0 g. of a lO% total solids solution of the above copolymer (16.4 g.
dry copolymer), (2) 218.0 g. styrene and (3) 6.0 g. ammonium persulfate in 24~2 g. distilled water. The kettle contents were stirred and heated to 88 C. The contents of the ~3~

three funnels were added over a period of three hours as the kettle temperature was maintained at 88-93C. After heating for an additional fifteen minutes, the product was cooled to room temperature. The product was a white latex containing 25.2~ solids. Approximately half of the latex was dialyzed using a 48 angstroms regenerated cellulose membrane to remove unreacted water-soluble prepolymer.
A 240.0 g. sample of the dialyzed latex (50.0 g. dry polymer, 0.056 mole acrylamide) was placed in a reaction kettle, and the pH was adjusted from 4.2 to 9.1 with 0~9 mlO
of lM sodium hydroxide solution. Glyoxal (16.2 g. of a 40%
aqueous solution 0~112 mole) was added, and the pH was ad-justed from 6.2 to 9.0 with 0.8 ml. of lM sodium hydroxide solution. Water (56 ml.) was added to reduce the reaction ]5 solids. The mixture was heated for four hours at 50C.
and the pH was then lowered to 2.0 with 0.5 ml. of concen-trated hydrochloric acid. The final product contained 18.2% solids.
Exa~les 2-5 - 20 Four additional latexes were prepared by the method described in Example l, except the ratio of acrylamide to DMDAAC was varied as shown in Table l below.

~3~

~D
~1 ~ ~ ~O ~D O 0~ ~
o .....
,~ , ~ o o ,~ o ~J N U ~J
~1 ~1~ _ u~ E3 .....

I ~ co ~ r~
u~ ~ N .....
~ 1 ~ o ~ a~
r~ ~ ~1 ~i cn I ~ ~o~
X O O .....
a) d~ ~1 :S Ul 10 U:~ ~ Il') t~
I R.
O
_ Co O O O O O
,~ ~q ~ ~ . . . . . O
.~ Z u~ _ u~ ~ ~ ~D U) ~1 .~ _ ~ .,.f H >~ 00 CO Ot) CO 5 ~ 3 o c~
~ o ~ S~,0 CO ~ 00 ~ OD
,.
~1 d~ ,~ ~1-- ~ ~1 N ~ `1 0 O O O .,1 U~
O ~ (11 E~ U~ l U~ h ~l O O O O O 1~
tO
. o~ r~ ~ ell ~ E~ a) U~ . . - - -d~ . ~ ~
E~ ~ ~ ~ _ t) ~ ~ ~ ~ ~7 ~ ~ ~ 1~
O In ~ 0~1 C~
1 0 o r~ h E~ U~ ~~ g ;~ 1~ 1 ~ Pl d~ (1~ U~
~ ~ ........ ~ -F~ ~ h ~q . ~ o o o o o lo U -æ c) ~ 0 1~ o ~ _ ... .. ,~
a~ ~ ~ ~ ~ o a~ ~ ~ 3 u~ ~ O
OR t~l a) _ u) ~
h _ co ~ ) ~ oo co i~l ~1 P~ ~ o _ co c~ a Zu~-, ~,i~,i,i ~ X ~cr~ a _ a~ ~P O_ . . . ~
~1 ~ ~ ~ ~ ~ In ~--¦ 1~ Ll) 01--ul ~ W ~I h 1I h æ

t N ~C O
~ ~ o ~:1 _ t~l Lt) o ~ u~ 1~ ~ ~
~ tJ ~ I` O ~D 1`
I¢ ~d I~
x~ x , Example 6 ~._ The compositions of Examples 1-5 were eva~uated as fillers for paper. Handsheets were prepared on a Noble &
Wood handsheet apparatus. The pulp consisted of a 50:50 blend of bleached hardwood:bleached softwood pulps beaten to a Canadian Standard Freeness of 300 cc. The paper was made at a pH of 4.5 (sulfuric acid, no alum). The latexes were evaluated at addition levels of 4% and 8~ ~dry basis).
The controls were unfilled paper and paper filled with 10%
and 20% kaolin clay. The clay was retained through the use of 1% alum and 0.05% of a high molecular weight cationic polyacrylamide retention aid. The results of testing of the paper are summarized in Table 2 below.

~3~

m _ ~ ~D o U~ a~ ~ ~ co N ~
1~ ~o a) . ~ o o ~ a~ ~ cs~ co _ ~ :
_ ~ :
_ ~ ~ U~ o 1~ o ~ U~ ~ ~ CO ~
" r~ O ~ ~ QD ~ O u~ ~ ~ ~ ~ ~n O . '~
E~

~ a~ o i~ ,1 ~;r N tD N r-l 3 Q ~ a~ ~ ~r ~ O O ,1 ~
E~ m ~ Q ~ ~

~ o ~
O dP a o~ ~ o ~ o~O ~ ~

~l o ~p~ o oo r-l N
oP
S~ ,J ~ r~

':4 ZIY~ 3 Q~ ~ D

~L~3(~

Example 7-10 Four latexes were prepared by the method described in Example 1 using 10% of various acrylamide-DMDAAC copoly-mers. The latexes were not reacted with glyoxal. The con-ditions for the latex syntheses are outlined in Table 3.
Example 11 The graft copolymers of Examples 7-10 were evaluated as fillers for paper by the method described in Example 6.
Test results are summarized in Table 4.
]0 Examples 12-16 Several latexes were prepared by the method described in Example ] with the exception that the water-soluble pre-polymers used to prepare the graft copolymers were copoly-mers of acrylamide and methacryloyloxyethyltrime~hylammon-ium methyl sulfate (MTMMS). The reaction conditions are summarized in Table 5. The latexes were not reacted with glyoxal.
Example 17 The qraft copolymer particles of Examples 12-16 were evaluated as fillers for paper by the method described in ; Example 6. A commercial polystyrene latex was used as an additional control in this experiment. The particles in the polystyrene latex bore negative charges and as a re-su]t a retention aid was used as shown.
Example 18 ~ Clay and a commercial polystyrene latex were eval-; uated as fillers ~or paper by the method described in `~ Examp]e 6. The two fillers were evaluated both with and without a cationic polyacrylamide retention aid. Test re-sults are summarized in Table 7.

.~

_, _-u a) o o u~
rl N--O
~ ~ I I ~ I
t~:l ~ 1" C ct) O O O
U~
~ ~ o r- ~ O
.,1 . . . . ~r~

U~ ~ 0 ~P
~r co_ o o o o ~1 X ~0 ~ . . ~
Z N ~ O O
d ~l U u~
1~ U~
I G)^ ~ O
. oo CO 00 00 r u~ h ~ ~ ~~`J ~`J u~~,1 S

S~
E~ ~ a ~
dP ;~ 1 _ o ~1 ~ ooo~
,J O ~ ~ ,1 ~ ~1 -- ~ ~ ~ ~ ~ ~ ~
O O ~ ~ ,1 a~U u~ ~ ~ ~ o ~
,~ u~ P~ a~
Q a~ ~ ~ OD ~1 oI ) tn O
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Dimethylaminoethylmethacrylate (157 g.) was added dropwise to 98 g. of 37% hydrochloric acid. Cooling was necessary to maintain the temperature below 30C. Water (381 cc.) and sopropanol (12.2 cc.) were added giving a 30 solution. This solution was heated to 50C. and sparged with nitrogen for 30 minutes followed by heating to 75C.
and adding 3.6 cc of O.]M FeSO4 7H2O followed by 10.9 cc. of t-butylhydroperoxide (90%). When the catalyst addi-t;on was completed the solution was stirred for 30 minutesand cooLed to room temperature. The viscous solution was diluted to 15.85% solids. RSV = 0.53 (lM NaCl, 1~, 25C.).
A water-jacketed two liter resin kettle equipped with ]5 a thermometer, stirrer, condenser, and three addition funne~s was charged with 269 cc. of distilled water. The funnels were charged with: (1) 183 g. of a 12.3~ aqueous solution of the poly(methacryloyloxyethyldimethylammonium chloride), prepared as above, (2) 225 g. styrene and (3) 6 9. ammonium persulfate in 25 cc. of distilled water. The contents of the kettle were stirred and heated to 88C.
under nitrogen. The contents of the funnels were added, dropwise, over a period of two hours as the kettle tempera-ture was maintained at 88-95.5C. After heating for an additional fifteen minutes, the product was cooled to room temperature. The final product was free of styrene and had a total solids of 36.4%.
~e~
Poly(methacryloyloxyethyldimethylammonium chloride) was prepared as in Example 19 except the solution was dilut-ed to 30~ solids instead of 15.85~. 161.5 g. of this 30%
solution was placed into a reaction vessel with 359 g. dis-tilled water. The pH of the solution was adjusted from 1.9 to 1.0 with 3.6 cc. of concentrated HCl. Epichlorohydrin (34.7 g.) was added to the reaction vessel giving 15~ reac-tion solids. 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. Total solids = 12.3%.

~L3~

A water-jacketed two liter resin kettle equipped with a thermometer~ stirrer, condenser, and three addition funnels was charged with 269 cc. of dist;lled water. The funnels were charged with tl) 183 g. oE a 12.3% aqueous - 5 solution of the water-soluble epichlorohydrin modified pre-po~ymer prepared as above, (2) 225 g. styrene and (3) 6 g.
ammonium persulfate in 25 cc. of distilled water. The con-tents of the kettle were stirred and heated to 89C. under nitrogen The contents of the funnels were added, dropwise, over a per;od of two hours as the kettle temperature was maintained at 89-97C. After heating for an additional fifteen minutes, the product was cooled to room temperature.
The final product was free of styrene and had a total solids of 3~.8%
Example 21 A reaction kettle was charged with 4130 g. of dis-tilled water and 145.5 g. of a 51.95% aqueous solution of poly(methyldiallylammonium chloride). The contents of the kett]e were heated to 87C. under nitrogen. 228 g. poly-(methyldiallylammonium chloride) in 1597 g. of distilledwater, 3040 g. styrene, and 83.7 g~ ammonium persulfate in 33~ g. of distilled water were added simultaneously, drop-wise, over a period of two hours. Tlle temperature was main-tained at 87-100C. The contents of the kettle were stirred for an additional 15 minutes, cooled to raom temper-ature and filtered through a 100-mesh screen. The resulting latex had a total solids of 37.2% and the particle size was 0.5 micron as measured by the Loebel Method (see Table 5).
806.5 g. of the above latex (300 g. solids) was placed into a reaction flask and the pH adjusted from 1.6 to 1.1 with 8.8 cc. of concentrated hydrochloric acid. Epichlorohydrin (34.2 g.) was added followed by stirring at room tempera-ture. As the reaction progressed the pH rose to 7.3 at which time the pH was adjusted to 1.55 with concentrated hydrochlGric acid. The resulting latex had a solids content of 37~.
Exam~le 22 A reaction vessel was charged with 200 g. of distilled water, 0.24 g. acetic acid, 3.64 g. sodium acetate and 1 g.
isopropanol. This was heated to 60C. under nitrogen and held for 15 minutes. Methylolacrylamide (40 g. in 160 g.
distilled water), methyldial]ylammonium chloride (13.3 g. in 53.1 g. distilled water) and ammonium persulfate (0=8 g. in 20 g distilled water) were added simultaneously, dropwise, over a period of about 1.8 hours, followed by stirring for one hour. The viscous copolymer so]ution was cooled to room temperature and the pH adjusted from 5.0 to 7.2 with 1.4 cc.
of 5M NaOH. Total solids of the reaction mass was 12.8~.
The latex synthesis consisted oE charging a reaction kettle with 493 g. of distilled water, 54.4 9. of a 10% aqueous so]ution of the copolymer above prepared and heating to 89C. under nitrogen. 16~ g. of a 10% aqueous solution of the copolymer above prepared, styrene (218 9.) and ammonium persulfate (6 g. in 24.2 g. of distilled water) were added simultaneously over a period of two hours. The temperature was control]ed at between 89-96C. After stirring for fifteen minutes the ]atex was cooled to room temperature and filtered through a 100-mesh screen. The filtered latex had a solids content of 26~.
Example 23 A reaction vessel was charged with 200 g. of distilled water, 0.24 g. acetic acid, 3.64 g. sodium acetate and 1.5 g. isopropanol. This was heated to 60-62C. under nitro-gen and held for 15 minutesO Methylolacrylamide (40 9. in 160 g. distilled water), dimethyldiallylammonium chloride (13.3 g. in 53.] gO distilled water) and ammonium persulfate (0.8 g. in 20 g. distilled water) were added simultaneously, 3~ dropwise, over a period of two hours followed by stirring ~or one hour. The copolymer solution, which had a solids content of 12.3%, was cooled to room temperature and the pH
adjusted to 7.3 with 0.5 cc. 5M NaOH. A reaction kettle 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 kettle were heated to 88-90C. under nitro-gen. 164 g. of a 10~ aqueous solution of the above copoly-mer, 218 g. styrene and 6 g. of ammonium persu]fate in 24.2 cc. of distilled water were added simultaneously, dropwise, over a period of about two hours to the reaction kettle.
After addition was complete the contents of the kettle were stirred for 15 minutes and cooled to room temperature. The resulting latex had a solids content of 25.4%.
Exam ~e 24 A reaction vessel was qharged with 170 cc. of dis-t;lled water and heated to 85C. under nitrogen sparge.
After a 15 minute sparge, acrylamide (110.3 g. in 257.3 cc.
distilled water), methyldiallylammonium acetate (133.2 g.
of a 29.8~ aqueous solution) and ammonium persulfate (7.5 g. in 71.3 cc. distilled water) were added simultaneously, dropwise, over a period of 1.75 hours followed by stirring - 15 minutes and cooling. Total Solids = 20.4%, RSV = 0.35 (lM NaCl, 1%, 25 C.).
The latex synthesis consisted of charging 798 cc. of distilled water and 1308 g. of a 10~ aqueous solution of the copolymer prepared as above to the reaction vessel.
This was heated to 93C. under nitrogen. Styrene (1308 9.), t-butylhydroperoxide (14.6 9. in 127.6 g. of distilled water) and sodium formaldehyde sulfoxylate (14.4 g. in 127.8 cc. distilled water) were addled simultaneously, drop-wise, over a period of three hours followed by stirring for 15 minutes and cooling to room temperature. The latex was filtered through a 100-mesh screen. Total Solids = 39.7%.
Particle size = 0.65 micron - measured by the Loebel Method - see Table 5.
Example 25 Glyoxal modification of the latex of Example 24 was carried out as follows: 214 9. of the above latex was placed into a reaction vessel. The pH was adjusted from

4.9 to 8.5 with 1.4 cc. of 5M NaOH. Glyoxal (9.3 g. in 13.9 9. distilled water) was added giving a pH of 6. This was readjusted to 8.5 with 1.3 cc. of 5M NaOH. The latex-glyoxal mixture was allowed to stir while maintaining thepH at 8.5 with periodic addition of a total of 0.2 cc. 5M
NaOH. After about 30 minutes the viscosity increased from 31 to 60 cps. The reaction was terminated by adding 0.4 cc. of concentrated H2SO4. Total solids = 39.2%.
~ 6 Latexes of Examp]es 24 and 25 were evaluated as fill-ers for paper by the method described in Example 6.
Results are set forth in Table 8 below.
Table 8 Basis Weight (lb./Tensile Mullen (l) 3000(lbs./ BurstOpacity Filler (~) sq.ft.) inO) ~psi) %
None 40.417.7 80.9 79.4 Example 24 (4) 41.2 1704 32.5 86.2 24 (8) 42.315.0 27.4 89.2 25 (4) 41.519.5 35.9 86.3 25 (8) ~2.317.6 30.9 89.3 Kaolin Clay* (10) 44.2 15.2 22.0 86.2 (20) 47.6 12.6 17.9 89.4 * 0.05~ of a cationic polyacrylamide, based on the weight of the paper, was employed as a retention aid for the kaolin clay.
( ) Opacity measured in accordance with Tappi Standard T-425 (Diano Opacimeter) Example 27 A water-jacketed resin kettle equipped with a ther-`~ mometer, a stirrer, a condenser and four addition funnels was charged with 30.0 9. of distilled water, 0.6 g. acetic acid, and 0.85 g. sodium acetate. The funnels were charged 30 with: (1) 60.0 g. styrene, (2) 6.0 g. chitosan, 6.0 9.
acetic acid, and 114.0 g. distilled water, (3) 0.65 g. of a 20% aqueous solution of t-bu~ylhydroperoxide, and 25.0 9.
distilled water, and (4) 0.65 g. sodium formaldehyde sul-foxylate and 25.0 g~ distilled water. The kettle contents were stirred and heated to 88C. ~he contents of the four funnels were added, dropwise, over a period of four hours as the kettle temperature was maintained at 60C. After heating for an additional thirty minutes, the product was cooled to room temperature, not all styrene reacted and the unreacted styrene was removed with a rotary evaporator. The product was a latex having a solids content of 28.8%. The ~3~

particles of this latex were evaluated as paper fillers by the method of Example 6. Results are set forth in Table 9 below.
Table 9 Basis Weight Ten-(lb./ (1) sile Mullen 3000 Opa~ity (lbs./ Burst F-iller (~ sq.ft.) (%) _ in.) (psi) 10 None 40.6 80.0 18.8 31.9 Example 27 (4) 40.8 84.1 18.5 28.8 (8) 41.9 ~6.6 17.7 28.5 Kaolin Clay* (10) 44.6 85.7 15.2 23.0 (20) ~6.3 87.5 13.3 18.6 Commercial Polystyrene* (4) 41.0 83.5 17~7 28.3 (8~ 41.2 86.1 16.3 26.3 * 0.05% of cationic polyacrylamide, based on the weight of the paper, was employed as a retention aid for the 20filler.
( )Opacity measured in accordance with Tappi Standard T-425 (Hunter Opacity Meter).
The unique advantages of the organic pigments of this invention can best be illustrated by considering the data in Tables 1 and 2. The organic pigments were added in amounts of 4~ and 8~ and were compared to kaolin clay added in amounts of 10~ and 20% (equivalent in volume to 4% and 8~ of the organic pigments of this invent:ion). Alum and a high molecular weight cationic polyacrylamide were used as reten-tion aids for the kaolin clay. No retention aid was usedwith the organic pigments of this invention. The opacity of filled paper is a measure of the retention of the filler in the paper.
The dry tensile and Mullen Burst data in Table 2 il-lustrate the strength advantages provided by the organic pigments of the present invention. It can be seen that -~ kaolin clay decreases the strength properties relative to unfilled paper by about 20-30%. In contrast, the organic pigments of this invention that give the highest opacity (compositions of Examples 3 and 4) also give strength improvements of about 5-15% relative to unfilled paper.

~L~L3~
-3~-Comparing these organic pigments to clay, the for~er give opacity equivalent to the latter and in addition, have strength properties 20-50~ higher than the latter.
One further advantage of the fillers (organic pig-ments) of this invention is evident in Table 2. The clay-filled paper is considerably heavier than the control, while the paper containing the filler of this invention is only slightly heavier than the control.
The data in Tables 3 and 4 summarize the evaluation of a simi]ar series of organic pigments stabilized using acryl amidedimethyldiallylammonium chloride copolymers as the water-soluble cationic pLepolymer but not reacted with glyoxal. Because there is no reactive functionality on the particles, the strength properties were poorer in this ex-periment than in the previous one.
The data in Tables 5 and 6 summari~e a similar experi-ment in which the organic pigments were prepared using vari-ous copolymers of acrylamide and methacryloyloxyethyltri-methy]ammonium methyl sulfate as the water-soluble cationic prepolymer. Since there was no reactive functionality on the particles, strength values were slightly poorer than the control in some cases but always significantly better than for the clay-filled paper. For further comparison, a com-mercially available polystyrene latex was evaluated in this experiment. The particles in this latex have anionic charges, so alum and a polymeric retention aid were used.
The data show that the polystyrene particles gave paper hav-ing slightly higher opacity than the organic pigments of this invention tbUt also higher basis weight). The polysty-rene particles decreased paper strength, although not quiteas much as did the clay~
The data in Table 7 show that conventional fillers like clay and polystyrene require retention aids for optimum performance. Without retention aids opacity is very low in bo~h cases. As shown in Tables 2, 4 and 6, the organic pig-ments of the present invention provide good opacity without the use of any retention aidO

~xample -A water-jacketed reaction vessel fitted with a ther-mometer, a stirrer, a condenser, and an addition funnel was charged with 89 grams distilled water and 436 grams of a 10%
aqueous solution of poly(methyldiallylammonium chloride).
The resulting solution was heated to 87-88C. by circu-lating hot water through the jacket of the reaction vessel~
Styrene (425.2 grams) and divinylbenzene (10.9 grams) were mixed and placed in the addition funnel. 13.3 Grams of a 90% aqueous solution o t-butylhydroperoxide and 108 grams of distilled water were placed in a burette; and 13.6 grams of sodium hisulfite dissolved in 124.5 grams distilled water were placed in another burette. The mixture of styrene and divinylben~ene; the t-butylhydroperoxide solution; and the sodium bisulfite solution were added dropwise, simultan-eously, over a period of 2 hours to the contents of the reaction vessel. After stirring for 20 minutes, a slight odor of styrene was evident. Additional t-butylhydroper-oxide solution (3.4 grams of t-butylhydroperoxide dissolved in 27 grams distilled water) and additional sodium bisulfite solution (3.4 grams sodium bisulfite dissolved in 31 grams of distilled water) were added to the reaction mass and the reaction mass was stirred for an additional 20 minutes. The resultlng ]atex was cooled to room temperature and filtered through a 100 mesh screen. Total solids = 27.7%. Particle size = 0.8 micron - measured by Coulter Counter.
~ s previously set forth, polyethylenically unsatur-ated monomers, such as divinylbenzene, can be used in admix-ture with monoethylenically unsaturated monomers to provide crosslinked graft copolymer particles. Examples of other suitable polyethylenically unsaturated monomers that can be used for this purpose are diallyl phthalate, ethylene glycol dimethacrylate, 1,3-butylene glycol dimethacrylate, 1,6-hexanediol dimethacrylate, polyethylene glycol dimethacry-late, polypropylene glycol dimethacrylate, trivinylben~ene,divinylnaphthalene, diallyl maleate, diallyl fu~larate, trimethylol propane trimethacrylate, and pentaerythritol ! tetraacry~ate. The preferred polyethylenically unsaturated monomers, also referred to as crosslinking monomers, are divinylbenzene, diallyl phthalate, ethylene glycol dimeth-acrylate, and 1,3-butylene glycol dimethacrylate.
Whi]e the organic pigments of this invention have par-ticular utility as paper fillers, they can also be used inpaper coatings together with a suitable binder thereforO
Furthermore, they can be used in paints, inks, and the like.
They can also be applied as coatings, together with a suit-able binder, to glass surfaces, metal surfaces, wood sur-0 faces, plaster surfaces and the like.Example 29 A water-jacketed resin kettle equipped with a ther-mometer, a stirrer, a condenser and three addition funnels was charged with 75.0 g. of distilled water. The funnels were charged as follows: funnel (1) with 35.0 g. acrylamide (0.49 mole) in 70.0 g. distilled water, funnel (2) with 15.0 g. vinylbenzyltrimethylammonium chloride (0.07 mole) in 60.0 g. distilled water, and funnel (3) with 1.25 g. ammonium persulfate in 50.0 g. distilled water. The kettle contents were heated to 80C., and the contents of the funnels were added, dropwise, over a period of 2-1/2 hours as the temper-ature was maintained at 80-85C. After heating for an additional 30 minutes, the solution was cooled to room tem perature (about 23C.). ~he product solution contained 22.0~ solids and had an RSV, reduced specific viscosity, of 0.27 (1% solution in lM NaCl, 25C.~.
A water-jacketed resin kettle fitted with a thermom-eter, a stirrer, a condenser and three addition funnels was charged with 503.8 g~ of distilled water and 26.2 g. of the above copolymer solution (5.8 g. dry copolymer). The fun~
nels were charged as follows. funnel (1) with 78.6 g. of the above copolymer solution (17.3 g. dry copolymer) plus 120.0 g. distilled water, funnel (2) with 230.0 g. styrene, and funnel (3) with 5.1 g. ammonium persulfate in 120.0 g.
distil]ed water. The kettle contents were stirred and heated to 79C. The contents of the three funnels were added, dropwise, over a period of four hours as the kettle temperature was maintained at 79-88C. ~fter heating for ~ 3~

an additional 15 minutes, the product was cooled to room temperature, and the pH was adjusted from 1.9 to 7.5 with 25% sodium hydroxide solution. The product was filtered through a 100 mesh sieve. The product was a white latex containing 25.1~ ~otal solids and;having an average par-ticle si~e of 0.62 micron (m~thod of A. B. Loebel, Official Digest, 200, February, 1959), Example 30 A water-jacketed resin kettle e~uipped with a ther-mometer, a stirrer, a condenser and two addition funnels was charged with 200 g. of distilled water. The funnels were charged as follows: funnel ~1) with 77.0 g. acrylamide (1.08 mole), 1701 g. 4-vinylpyridine (0.16 mole), and 16.0 g. concentrated hydrochloric acid solution (0.19 mole) in 200 g. distilled water, and funnel (2) with 2.5 g. ammonium persulfate in 100 g. distilled water. The kettle contents were heated to 80C., and the contents of the funnels were added, dropwise, over a periad of 2 hours, Z5 minutes as the temperature was maintained at 80-85C. After heating for an additional 30 minutes, the solution was cooled to room temperature (about 23C.). The product solution con-tained 21.6% solids and had an RSV, reduced specific viscos-it~, of 0.34 (1% solution in lM NaCl, 25 ~.).
A water-jacketed resin kettle fitted with a thermom-eter, a stirrer, a condenser and three addition funnels was charged with ~U3.4 g. of distilled water and 26.6 g. of the above copolymer solution (5.7 g. dry copolymer). The fun-ne]s were charged as follows: funnel (1) with 79.8 9. of the above copolymer solution (17.2 g. dry copolymer) plus lZ0 g. distilled water, funnel (2) with 230 g. styrene, and - funnel (3) with 5.1 g. ammonium persulfate in 120.0 g. dis-tilled water. The kettle contents were stirred and heated to 78C. The contents of the funnels were added, drop-wise, at the same time. The çontents of funnels (1) and (2) were added over a period of 4 hours. The contents of funnel (3) were added over a period of 4 hours, 15 min~tes. The kettle temperature was malntained at 78-84C. throughout the additions. The product was cooled to room temperature, . . ` , ~ .

and the pH was adjusted Erom 2.0 to 4.6 wlth 10~ sodium hy-roxide solution. The product was filtered through a 100 mesh sieve. The product was a white latex containing 25.8~ total solids and having an average particle size of 0.45 micron (method of Loebel, Official Digest, 200, February, 1959).
Example 31 A water-jacketed resin kettle equipped with a ther-mometer, a stirrer~ a condenser and two addition funnels was charged with 200 g. of distilled water. The funnels were charged as follows: funnel (1~ with 69.0 9. acrylamide (0.97 mole) and 31.0 g. methacrylamidopropyltrimethyl-ammonium chloride (0.14 mole) in 200 9. disti]led water, and funnel (2~ with 2.5 g. ammonium persulfate in 100 9. dis-tilled water. The kettle contents were heated to 77C., and the contents of the funnels were added, dropwise, over a period of 2-1/2 hours as the temperature was maintained at 77-85C. After heating for an additional 15 minutes, the solution was cooled to room temperature (about 23C.).
The product solution contained 22.7% solids and had an RSV, reduced specific viscosity, of 0.52 (1% solution in lM NaCl, 25C.).
A water-jacketed resin kettle fitted with a thermom-eter, a stirrer, a condenser and three addition funnels was charged with 504.7 9. of distilled water and 25.3 g. of the above copolymer solution (5.7 g. dry copolymer). The fun-nels were charged as follows: funnel (1) with 76.1 9. of the above copolymer solution !17.3 g. dry copolymer) and 120.0 g. distilled water, funnel (2) with 230.0 g. styrene, and funnel (3) with 5.1 g. ammonium persulfate in 120 g.
distilled water. The kettle contents were stirred and heated to 79C. The contents of the funnels were added, dropwise, at the same time. The contents of funnels (1) and (2) were ~dded over a period af 4 hours. The contents of funnel (3) were added over a period o 4 hours, 15 minutes.
The kettle temperature was maintained at 79-87C. through-out the additions. The product was cooled to room tempera-ture, and the pH was adjusted from 2.1 to 8.0 with 25%
sodium hydroxide solution. The product was filtered through :~3~

a lOO mesh sieve. The product was a white latex containing 25.5~ total solids and having an average particle size of 0.47 micron (method of Loebel, Official Digest, 200, February, l959).
~
A water-jacketed resin kettle equipped with a ther-mometer, a stirrer, a condenser and two addition funnels was charged with 200 g. of distilled water. The funnels were charged as follows: funnel (1) with 67 g. acrylamide (0.94 mole) and 33 g. 3-methacryloyloxy-2-hydroxypropyltrimethyl-ammonium chloride (0.14 mole) in 200 9. distilled water, and funnel (2) with 2.5 g. ammonium persulfate in 100 9. dis-ti]led water. The kettle contents were heated to 80C., and the contents of the funnels were added, dropwise r over a period of 2 hours, 25 minutes as the temperature was main-tained at 80-84C. After heating for an additional 15 minutes, the solution was cooled to room temperature (about 23C.). The product solution contained 21.3~ solids and had an RSV~ reduced specific viscosity, of 0.46 tl~ solution in lM NaCl, 25 C.).
A water-jacketed resin kettle fitted with a thermom-eter, a stirrer, a condenser and three addition funnels was charged with 503 g. of distilled water and 27 g. of the above copolymer solution (5.8 g. dry copolymer). The fun-nels were charged as follows: funnel (1) with 81 g. of the I above copolymer solution (17.3 g. dry copolymer) and 120 9.
di~tilled water, funnel (2) with 230 g. styrene, and funnel - (3) with 5.1 g. ammonium persulfate in 120 g. distilled wat- er. The kettle contents were stirred and heated to 77C.
The conten~s of the funnels were added, dropwise, at the same time. The contents of funnels (1) and (2) were added over a period of 4 hours. The contents of funnel (3) were added over a period of 4 hours, 15 minutes. The kettle tem-perature was maintained at 77-88C. throughout the addi-tions. The product was cooled to room temperature, and thepH was adjusted from 1.9 to 6.5 with 25% sodium hydroxide solutionO The product was filtered through a 100 mesh sieve. The product was a white latex containing 25.5% total solids and having an average particle size of 0.8 micron (method of Loebel, Official Digest, 200, February, 1959).

The compositions of Examples 29-32 were evaluated as ~illers for paper. Handsheets were prepared on a Noble &
Wood handsheet apparatus. The pulp consisted of a 50:50 blend of bleached hardwood~bleached softwood pulps beaten to a Canadian Standard Freeness of 500. The paper was made at a pH of 4.5 (sulfuric acid, no alum). The latexes were evaluated at addition levels of 4% and 8% (dry basis~. The control was unfilled paper. The results of testing of the paper are summarized in Table 10 below r~
-a I ou~ ~ o p ~1 ('`I O i''7 N O f~
~: m~ ~~ ~ ~ ~ ~ ~ ~ ~ s, a~
~ ~
'~.1:_ N~r ~ a~ ll') ~ O l.D Lt~ ~
~ ~ ~i~1~ ~I N N ~1 N t~ N S-l Q _ ~ O
O

~ a . . . . . . . ~r ~_ o~I t~ r) N (~ a~
O m a) ~ r o ~ o v O~o ~ co ~ a~ n c~
O E~ ~
_ 3 er O " O~
~ o ia o ~ o ~ ~ o ~ ~ ~ v ~1 0 tn ~
m U~
e~

d~ ~ O O O
~ o i4 ~ X X X X -1 N '1 ~L3~
.
--~o--The novel organic pigments of this invention can be used alone or in combination with other organic pigments, or inorganic pigments or both as fillers and coatings for paper. :
The above description and examples are illustrative of this invention and not in limitation thereof.

Claims (45)

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. Water-insoluble graft copolymer particles consisting essen-tially of the free radical catalyzed graft copolymerization product of (1) at least one ethylenically unsaturated monomer and (2) a water-soluble cationic prepolymer having an RSV of about 0.1 to about 2.5 (1M NaCl, 25°C.), the prepolymer moiety of the graft copolymer particles being present on the surface of the particles, said monomer (1) being selected from the group consisting of methyl alphachloroacrylate, ethyl alphachloroacrylate, methyl methacrylate, isopropyl methacrylate, phenyl methacrylate, vinyl chloride, acrylonitrile, methacrylonitrile, and monomers having the formula wherein R is hydrogen or methyl, Y

is methyl or chlorine, and n is 0, 1, 2 or 3, and said pre-polymer (2) being the addition polymerization product of (i) about 5 mole per cent to 100 mole per cent of at least one cationic monomer selected from the group consisting of (I) wherein R1 is hydrogen or methyl, R2 is hydrogen or a C1-C4 alkyl, R3 is hydrogen, a C1-C4 alkyl, where Y is hydroxyl or halogen, and -(-CH2CH20)nH where n is an integer 1 or more and X? is an anion, (II) wherein R1 is hydrogen or a C1-C4 alkyl, R2 is hydrogen, a methyl, ethyl, propyl, isopropyl, t-butyl, hexyl, octyl, decyl, dodecyl, tetradecyl or octadecyl alkyl, or a carboxylate, cyano, ether, amino, amide, hydrazide or hydroxyl substituted methyl, ethyl, propyl, isopropyl, t-butyl, hexyl, octyl, decyl, dodecyl, tetradecyl or octadecyl alkyl, and R3 and X are as defined in formula (I), (III) wherein R1, R2, R3 and X are as defined in formula (I), (IV) wherein R1, R3 and X are as defined in formula (I), (V ) X

wherein R1, R2, R3 and X are as defined in formula (I), and n is an integer 1, 2 or 3 and (VI ) wherein R1, R2, R3 and X? are as defined in formula (I), and (ii) from about 95 mole per cent to 0 mole per cent of at least one ethylenically unsaturated nonionic monomer selected from the group consisting of N-vinyl pyrroli-done, ethylenically unsaturated monomers having amide functionality, and ethylenically unsaturated monomers having hydroxyl functionality, the amount of prepolymer (2) employed in preparing the graft copolymer particles being from about 1 part to about 25 parts by weight for each 100 parts by weight of monomer (I) employed.

2. The water-insoluble graft copolymer particles of claim 1 wherein monomer (1) is styrene and (i) of prepolymer (2) is the monomer of formula (I), and (ii) of prepolymer (2) is a mono-ethylenically unsaturated amide, the amount of prepolymer (2) employed in preparing the graft copolymer particles being from about 2 parts -to about 10 parts by weight for each 100 parts by weight of monomer (1) employed, and -the RSV of the prepolymer being about 0.1 to about 1Ø

3. The water-insoluble graft copolymer particles of claim 1 wherein monomer (1) is styrene and (i) of prepolymer (2) is the monomer of formula (II) and (ii) of prepolymer (2) is a mono-ethy-lenically unsaturated amide, the amount of prepolymer (2) employed in preparing the graft copolymer particles being from about 2 parts to about 10 parts by weight for each 100 parts by weigh-t of monomer (1) employed, and the RSV of the prepolymer being about 0.1 to about 1Ø

4. The water-insoluble graft copolymer particles of claim 1 wherein monomer (1) is styrene and (i) of prepolymer (2) is the monomer of formula (III), (IV) (V) or (VI) and (ii) of prepolymer (2) is a mono-ethylenically unsaturated amide, the amount of pre-polymer (2) employed in preparing the graft copolymer particles being from about 2 parts to about 10 parts by weight for each 100 parts by weight of monomer (1) employed, and the RSV of the pre-polymer being about 0.1 to about 1Ø

5. The water-insoluble graft copolymer particles of claim 2,3 or 4 wherein (ii), the mono-ethylenically unsaturated amide, is acrylamide.

6. The water-insoluble graft copolymer particles of claim 2 wherein the prepolymer (2) is prepared from about 70 mole % to about 98 mole % acrylamide and from about 30 mole % to about 2 mole % dimethyldiallylammonium chloride.

7. The water-insoluble graft copolymer particles of claim 2 wherein the prepolymer (2) is prepared from about 67 mole % to about 98 mole % acrylamide and from about 33 mole % to about 2 mole %
methyldiallylammonium chloride.

8. The water-insoluble graft copolymer particles of claim 2 wherein the prepolymer (2) is prepared from about 70 mole % to about 98 mole % acrylamide and from about 30 mole % to about 2 mole %
methyldiallylammonium acetate.

9. The water-insoluble graft copolymer particles of claim 2 wherein the prepolymer (2) is prepared from about 70 mole % to about 95 mole % acrylamide and from about 30 mole % to about 5 mole %
methacryloyloxyethyltrimethylammonium methyl sulfate.

10. The water-insoluble graft copolymer particles of claim 3 wherein the prepolymer (2) is prepared from about 82 mole % to about 90 mole % acrylamide and from about 18 mole % to about 10 mole %
dimethyldiallylammonium chloride.

11. The water-insoluble graft copolymer particles of claim 3 wherein -the prepolymer (2) is prepared from about 67 mole % to about 89 mole % acrylamide and from about 33 mole % to about 11 mole %
methyldiallylammonium chloride.

12. The water-insoluble graft copolymer particles of claim 3 wherein the prepolymer (2) is prepared from about 82 mole % to about 91 mole % acrylamide and from about 18 mole % to about 9 mole %
methyldiallylammonium acetate.

13. The water-insoluble graft copolymer particles of claim 2 wherein the prepolymer (2) is prepared from about 70 mole % to about 88 mole % acrylamide and from about 30 mole % to about 12 mole %
methacryloyloxyethyltrimethylammonium methyl sulfate.

14. The water-insoluble graft copolymer particles of claim l wherein the prepolymer moiety of the particles has chemically bonded thereto a cellulose reactive group.

15. The water-insoluble graft copolymer particles of claim 2, 3 or 4 wherein the prepolymer moiety of the particles has chemically bonded thereto a cellulose reactive group.

16. The water-insoluble graft copolymer particles of claim 1, wherein the mono-ethylenically unsaturated amide is acrylamide and the prepolymer moiety of the particles has chemically bonded thereto a cellulose reactive group.

17. The water-insoluble graft copolymer particles of claims 2, 3 or 4 wherein the mono-ethylenically unsaturated amide is acrylamide and the prepolymer moiety of the particles has chemically bonded thereto a cellulose reactive group.

18. The water-insoluble graft copolymer particles of claims 6, 7 or 8 wherein the prepolymer moiety of the particles has chemically bonded thereto a cellulose reactive group.

19. The water-insoluble graft copolymer particles of claim 9, 10 or 11 wherein the prepolymer moiety of the particles has chemically bonded thereto a cellulose reactive group.

20. The water-insoluble graft copolymer particles of claim 12 or 13 wherein the prepolymer moiety of the particles has chemically bonded thereto a cellulose reactive group.

21. The water-insoluble graft copolymer particles of claim 6, 7 or 8 wherein the prepolymer moiety of the particles has chemically bonded thereto an aldehyde group.

22, The water-insoluble graft copolymer particles of claim 9, 10 or 11 wherein the prepolymer moiety of the particles has chemically bonded thereto an aldehyde group.

23. The water-insoluble graft copolymer particles of claim 12 or 13 wherein the prepolymer moiety of the particles has chemically bonded thereto an aldehyde group.

24. In the method of manufacturing paper wherein an opacifying agent is used to provide opacity in the final paper product , either by means of a coating or by means of internal addition to the paper pulp, the improvement wherein there is employed as at least a portion of the opacifying agent the water-insoluble graft copolymer particles of claim 1.

25. In the method of manufacturing paper wherein an opacifying agent is used to provide opacity in the final paper product, either by means of a coating or by means of internal addition to the paper pulp, the improvement wherein there is employed as at least a portion of the opacifying agent the water-insoluble graft copolymer particles of claims 2, 3, or 4.

26. In the method of manufacturing paper wherein an opacifying agent is used to provide opacity in the final paper product, either by means of a coating or by means of internal addition to the paper pulp, the improvement wherein there is em-ployed as at least a portion of the opacifying agent the water-insoluble graft copolymer particles of claim 1, wherein the mono-ethylenically unsaturated amide is acrylamide.

27. In the method of manufacturing paper wherein an opacifying agent is used to provide opacity in the final paper product, either by means of a coating or by means of internal addition to the paper pulp, the improvement wherein there is employed as at least a portion of the opacifying agent the water-insoluble graft copolymer particles of claims 2, 3 or 4 wherein the mono-ethylenically unsaturated amide is acrylamide.

28. In the method of manufacturing paper wherein an opacifying agent is used to provide opacity in the final paper product, either by means of a coating or by means of internal addition to the paper pulp, the improvement wherein there is employed as at least a portion of the opacifying agent the water insoluble graft copolymer particles of claims 6, 7 or 8.

29. In the method of manufacturing paper wherein an opacifying agent is used to provide opacity in the final paper product, either by means of a coating or by means of internal addition to the paper pulp, the improvement wherein there is employed as at least a portion of the opacifying agent the water insoluble graft copolymer particles of claims 9, 10 or 11.

30. In the method of manufacturing paper wherein an opacifying agent is used to provide opacity in the final paper product, either by means of a coating or by means of internal addition to the paper pulp, the improvement wherein there is employed as at least a portion of the opacifying agent the water insoluble graft copolymer particles of claims 12 or 13.

31. In the method of manufacturing paper wherein an opacifying agent is used to provide opacity in the final paper product, either by means of a coating or by means of internal addition to the paper pulp, the improvement wherein there is employed as at least a portion of the opacifying agent the water insoluble graft copolymer particles of claim l, wherein the pre-polymer moiety of the particles has chemically bonded thereto a cellulose reactive group.

32. In the method of manufacturing paper wherein an opacifying agent is used to provide opacity in the final paper product, either by means of a coating or by means of internal addition to the paper pulp, the improvement wherein there is employed as at least a portion of the opacifying agent the water-insoluble graft copolymer particles of claim 2, 3 or 4 wherein the prepolymer moiety of the particles has chemically bonded thereto a cellulose reactive group.

33. In the method of manufacturing paper wherein an opacifying agent is used to provide opacity in the final paper product, either by means of a coating or by means of internal addition to the paper pulp, the improvement wherein there is employed as at least a portion of the opacifying agent the water-insoluble graft copolymer particles of claim 6, 7 or 8 wherein the prepolymer moiety of the particles has chemically bonded thereto an aldehyde group.

34. In the method of manufacturing paper wherein an opacifying agent is used to provide opacity in the final paper product, either by means of a coating or by means of internal addition to the paper pulp, the improvement wherein there is employed as at least a portion of the opacifying agent the water-insoluble graft copolymer particles of claims 9,10 or 11 wherein the prepolymer moiety of the particles has chemically bonded thereto an aldehyde group.

35. In the method of manufacturing paper wherein an opacifying agent is used to provide opacity in the final paper product, either by means of a coating or by means of internal addition to the paper pulp, the improvement wherein there is employed as at least a portion of the opacifying agent the water-insoluble graft copolymer particles of claim 12 or 13 wherein the prepolymer moiety of the particles has chemically bonded thereto an aldehyde group.

36. A process for preparing a latex of graft copolymer particles which comprises graft copolymerizing in aqueous media and in the presence of a free-radical initiator (1) at least one ethylenic-ally unsaturated monomer and (2) a water-soluble cationic polymer having an RSV of about 0.1 to about 2.5 (1M-NaCl, 1% 25°C.), said monomer (1) being selected from the group consisting of methyl alpha-chloroacrylate, ethyl alpha-chloroacrylate, methyl methacrylate, isopropyl methacrylate, phenyl meth-acrylate, vinyl chloride, acrylonitrile, methacrylonitrile, and monomers having the formula wherein R is hydrogen or methyl, Y is methyl or chlorine, and n is 0, 1, 2, or 3, and said prepolymer (2) being the addition polymerization product of (1) about 5 mole per cent to 100 mole per cent of at least one cationic monomer selected from the group consisting of (I) wherein R1 is hydrogen or methyl, R2 is hydrogen or a C1-C4 alkyl, R3 is hydrogen, a C1-C4 alkyl, where Y is hydroxyl or halogen, and -(-CH2CH2O)nH where n is an integer 1 or more and X ? is an anion, (II) wherein R1 is hydrogen or a C1-C4 alkyl, R2 is hydrogen, a methyl, ethyl, propyl, isopropyl, t-butyl, hexyl, octyl, decyl, dodecyl, tetradecyl, or octa-decyl alkyl or a carboxylate, cyano, ether, amino, amide, hydrazide or hydroxyl substituted methyl, ethyl, propyl, isopropyl, t-butyl, hexyl, octyl, decyl, dodecyl, tetradecyl, or octadecyl alkyl, and R3 and X are as defined in formula (I), (III) wherein R1, R2, R3 and X are as defined in formula (I), (IV) wherein R1, R3 and X are as defined in formula (I), wherein R1, R2, R3 and X are as defined in formula (I) and n is an integer 1, 2 or 3 and wherein R1, R2, and R3 and X are as defined in formula (I), and (ii) from about 95 mole per cent to 0 mole per cent of at least one ethylenically unsaturated nonionic monomer selected from the group consisting of N-vinyl pyrrolidone, ethenically unsaturated monomers having amide functionality, and ethylenically unsaturated monomers having hydroxyl functionality, the amount of prepolymer (2) employed in preparing the graft copolymer particles being from about 1 part to about 25 parts by weight for each 100 parts by weight of monomer (1) employed.

37. The process of claim 36 wherein monomer (1) is styrene and (i) of prepolymer (2) is the monomer of formula (I), (II), (III), (IV), (V), or (VI) and (ii) of prepolymer (2) is a mono-ethylenically unsaturated amide, the amount of prepolymer (2) employed being from about 2 parts to about 10 parts by weight for each 100 parts by weight of monomer (1) employed and the RSV of the prepolymer is from about 0.1 to 1Ø

38. The method of claim 37 wherein (ii), the mono-ethyl-enically unsaturated amide is acrylamide.

39. The method of claim 36 wherein the prepolymer is, prior to graft copolymerization, reacted with a compound that will provide the prepolymer with cellulose reactive groups.

40. The method of claim 36 wherein the graft copolymer particles are subsequently reacted with a compound that will provide cellulose reactive groups on the surface of the particles.

41. Paper produced in accordance with the process of claim 24, 29 or 31.

42. The water-insoluble graft copolymer particles of claim 1 wherein there is employed in combination with monomer (1) a polyethylenically unsaturated monomer in an amount at least sufficient to provide cross-linked graft copolymer particles, said unsaturated monomer being selected from the group consisting of divinylbenzene; diallyl phthalate; ethylene glycol dimethacrylate;
1,3-butylene glycol dimethacrylate; 1,6-hexanediol dimethacrylate;
polyethylene glycol dimethacrylate; polypropylene glycol dimeth-acrylate; trivinylbenzene; divinylnaphthalene; diallyl maleate;
diallyl fumarate; trimethylol propane trimethacrylate; pentaery-thritol tetraacrylate; and mixtures thereof.

43. The water-insoluble graft copolymer particles of claim 2 wherein there is employed in combination with the styrene a polyethylenically unsaturated monomer in an amount at least sufficient to provide cross-linked graft copolymer particles, said unsaturated monomer being selected from the group consisting of divinylbenzene; diallyl phthalate; ethylene glycol dimethacrylate;
1,3-butylene glycol dimethacrylate; 1,6-hexanediol dimethacrylate;
polyethylene glycol dimethacrylate; polypropylene glycol dimeth-acrylate; trivinylbenzene; divinylnaphthalene; diallyl maleate;
diallyl fumarate; trimethylol propane trimethacrylate; pentaery-thritol tetraacrylate; and mixtures thereof.

44. The water-insoluble graft copolymer particles of claim 3 wherein there is employed in combination with the styrene a polyethylenically unsaturated monomer in an amount at least sufficient to provide cross-linked graft copolymer particles, said unsaturated monomer being selected from the group consisting of divinylbenzene; diallyl phthalate; ethylene glycol dimeth-acrylate; 1,3-butylene glycol dimethacrylate; 1,6-hexanediol dimethacrylate; polyethylene glycol dimethacrylate; polypropylene glycol dimethacrylate; trivinylbenzene; divinylnaphthalene;
diallyl maleate; diallyl fumarate; trimethylol propane trimeth-acrylate; pentaerythritol tetraacrylate; and mixtures thereof.

45. The water-insoluble graft copolymer particles of claim 4 wherein there is employed in combination with the styrene a polyethylenically unsaturated monomer in an amount at least sufficient to provide cross-linked graft copolymer particles, said unsaturated monomer being selected from the group consisting of divinylbenzene; diallyl phthalate; ethylene glycol dimethacrylate;
1,3-butylene glycol dimethacrylate; 1,6-hexanediol dimethacrylate;
polyethylene glycol dimethacrylate; polypropylene glycol dimeth-acrylate; trivinylbenzene; divinylnaphthalene; diallyl maleate;
diallyl fumarate; trimethylol propane trimethacrylate; pentaeryth-ritol tetraacrylate; and mixtures thereof.