NZ201950A - Water-soluble quaternary ammonium graft copolymers and uses therefor - Google Patents

Description

New Zealand Paient Spedficaiion for Paient Number £01 950 e f 9 5 o Priority Dats(s): .°?7.

Ccm;;!::j f^t-sriiDStlon Filed: %P..*?. .^| e,„rl, C026l3p^ ha!??; PP.'^d°Jj cog.Fl c*, n - • - - ,3 «6A ISfcS. ra ^ ^ p r' '? 1 »«3 %5*f _ fe? ■ ^ a Smtf. £ iM.™ Patents Font) No. 5 Number PATENTS ACT 1953 Dated COMPLETE SPECIFICATION QUATERNARY AMMONIUM GRAFT POLYMERS 2/We BUCKMAN LABORATORIES, INC. a corporation organised under the laws of the State of Tennessee, United States of America, of 1256 N. McLean Boulevard, Memphis, Tennessee, United States of America, do hereby declare the invention for which K/we pray that a Patent may be granted to fWJ/us, and the method by which it is to be performed, to be particularly described in and by the following statement: - 1 - (followed by page la) 201950 (107) ^ Background of the Invention The present invention relates to novel cationic graft copolymers and their uses as flocculants, dry strength additives for paper, and dye retention agents. More particularly, the present invention relates to quaternary ammonium graft copolymers prepared by graft polymerizing water-soluble vinyl monomers to quaternary ammonium ionene type polymers. This invention is related to the flocculation of suspended matter by the aforesaid polymers, and to paper of improved strength and dye retention prepared by use of the aforesaid polymers.

A number of methods are known in the art for the preparation of graft copolymers. These include radiation methods, both high energy radiation from gamma rays or electron accelerators and actinic, i.e. photochemical radiation. Chemical catalysts which are also used include free radical initiator systems such as the ferrous ion-hydrogen peroxide reaction which is very effective in promoting graft polymerization.

The present invention is not limited to any single method for initiation of the polymerization. However, the eerie ion initiation system taught by - la- 2019 50 M.rm Mino, et al. (U.S.P. 2,923,768) is particularly attractive. In this method it is believed that eerie ion reacts directly with a pendant reactive group such as hydroxyl group on the polymeric substrate. The radical which results frcm this initial reaction then may react with vinyl monomers present in solution | yielding a graft copolymer. Relatively little homopolymer is produced by this j technique unless large amounts of chain transfer agents are added.

| It has now been discovered that certain polyquaternary ammonium polymers j ! of the ionene type are active substrates for graft polymerizations. Graft i polymers produced by eerie ion-catalyzed graft polymerizations onto the afore- : said polyquaternary ammonium polymers are unusually effective as flocculants, : dry strength agents for paper, and dye retention agents.

Water-soluble cationic polymers have been used in a number of applications |, including the pulp and paper industry to increase strength and dye retention, I In water treatment to flocculate suspended solids, and in waste treatment to II j! help dewater sludge. New materials which are effective in these applications ; are constantly being synthesized and evaluated, and materials with improved | properties would be accepted readily.

! An object of this invention is to provide novel cationic graft copolymers.

^ Oc|79 5 0 Summary of the Invention I The present invention provides novel high-molecular-weight quaternary j J ammonium graft copolymers comprising a substrate portion and a grafted portion. ! The substrate is a water-soluble polymeric quaternary ammonium composition j having a plurality of hydroxypropylene groups having as a general structure | OH i I ! - A - CH0 - CH CH- - A - 1 l l , wherein A is a tertiary or quaternary nitrogen characterized in that the number , of quaternary nitrogen atoms exceeds the number of tertiary nitrogen atoms. The1 I graft portion comprises polymerized water-soluble nonionic, anionic, and cationic vinyl addition monomers. The amount of grafted vinyl addition polymer can vary' i between one-tenth and one hundred times the amount of substrate polyquaternary ' ammonium polymer. j The invention also,provides methods of utilising these graft copolymers to j I flocculate suspended inorganic and organic matter in - aqueous - solutions, to ! ) improve drainage and/or retention in the manufacture of paper,-to increase the ■ dry strength of paper, to increase dye retention, as well as other uses. | Detailed Description of the Invention j The graft copolymers of the present invention comprise a substrate portion; i.e., a previously made polymer, and a grafted portion. The substrate polymer ! i is a cationic polyquaternary ammonium polymer of the ionene type. In general, j these substrate polymers are made by the reaction of a ditertiary amine with \ i t epichlorohydrin. A convenient method to produce cationic polyquaternary ammonium polymers suitable for use in this invention is that described by Buckman, et al. in U.S. Patent 4,054,542. Complete descriptions concerning the details of the reactant species as well as the methods of preparation are contained therein. These polymers have a molecular weight of approximately ; I 40,000. j In addition to the polymers described above, other polymers described | I New Zealand Patent Specification 179387 can be utilized. These polymer j ! molecules have molecular weights in the ranee of 5,000. I A polyquaternary ammonium polymer may be distinguished from a polyamine ! by the functionality of the nitrogen atoms in the polymer. In a polyquater- j : nary ammonium polymer most of the nitrogens are quaternized, i.e., they are • I: covalently bonded to four carbon atoms. In a polyamine, most of the nitrogen ! : ! I; atoms are not quaternized. Polyamines will have nitrogen atoms which are j ■ primary, i.e., they are bonded to one carbon atom and two hydrogen atoms, i ; secondary, i.e., they are bonded to two carbons and one hydrogen, and tertiary, ; i : i.e., they are bonded to three carbons. In addition, polyamines may have some i . nitrogens which are quaternary; but these quaternary nitrogens will comprise considerably less than half of the total number "of nitrogen atoms. i ; A polyquaternary ammonium polymer is made from a ditertiary amine and j / another difunctional monomer, such as epichlorohydrin. The reaction between i the two monomers joins a carbon frcta the difunctional monomer to a nitrogen i on a tertiary nitrogen to produce a quaternary nitrogen. i In the process which produces polyamines only a minor amount of reactions occur which lead to quaternary ammonium groups. In general, a polyamine is ' made from a multifunctional amine, such as diethylene triamine, which will I i i contain some primary and some secondary nitrogens. The polymerization reactions i I between the multifunctional amines and difunctional monomers, such as epichloro-; hydrins, will change primary nitrogens to secondary nitrogens and secondary j' nitrogens to tertiary nitrogens. Inevitably some of the tertiary nitrogens jiformed from previous reactions will be converted to quaternary groups, but con- j ii ! siderably less than half of the nitrogens will be quaternized. 2 01950 (107) 9 !' Polyamines nay also be made from methylamine and epichlorohydrln, as i; j1 taught by Nagy in U.S. Patent 3,567,659. In this process a deliberate attempt i is made to reduce the amount of cross-linkages by minimizing the formation of quaternary nitrogens. The polyamine made by Nagy has the structure j, f3 j; [- N - CH2CH(0H) CH2 - j j; In solutions with an acid pH, these polyamines convert to the cationic form, ' e.g., the hydrochloride salt CH„ I [- N - CH2CH(0H) CH„-3 I ■+• H Cl~ The structure of a typical polyquaternary ammonium polymer used as a , substrate in the present invention has the general formula OH I - A - CH2 - CH - CH2 - A - where A is a tertiary or quaternary nitrogen atom characterized in that the number of quaternary nitrogen atoms always exceeds the number of tertiary nitrogen atoms.

In processes employed to make polyquaternary ammonium polymers, a 20 deliberate attempt is made to have as many nitrogen atoms as possible in the quaternary form. Over fifty percent of the nitrogen atoms in polyquaternary ; ammonium polymers are quaternary nitrogen atoms.

The grafted portion of the polymers of the present invention is made by i the graft polymerization of water-soluble vinyl monomers on to the backbone 25 i of the substrate. The water-soluble monomers employed in the present process ' include acrylamide, methacrylamide, acrylic acid, methacrylic acid, dimethyl-aminoethyl methacrylate, N,N-dimethylacrylamide, dlmethylaminopropyl- 2°1950! (107) | methacrylamide, methacrylamldopropyltrlmethylaramonlum chloride, dimethyl- ! i j diallylammonium chloride, the quaternization product of dimethylaminoethyl j methacrylate with methyl chloride, the quaternization product of dimethylaminoethyl methacrylate with dimethyl sulfate, and other water-soluble monomers which are readily apparent to those skilled in the art. Mixtures of two or more of the water-soluble vinyl monomers may also be used. J i Preferred mixtures include acrylamide with one or more of the other ' | monomers l«isted above. Most preferred mixtures are acrylamide and acrylic j; acid, acrylamide and dimethylaminoethyl methacrylate, acrylamide and the •j quaternization product of dimethylaminoethyl methacrylate with dimethyl sulfate, !; j and acrylamide and the quaternization product of dimethylaminoethjil metha- ! crylate with methyl chloride. Also included are mixtures of three or more ■ monomers, such as acrylamide, acrylic acid, and the quaternization product of j dimethylaminoethyl methacrylate with dimethyl sulfate.

!' The graft polymerization can be initiated in one of several ways. High energy radiation such as gamma rays or electron accelerators are convenient methods to use in many graft polymerizations. Likewise, photochemical initiation is a convenient source of radicals which are effective in promoting graft polymerizations. j The preferred method to initiate polymerization to produce the cationic j i polyquaternary ammonium graft copolymers of the present invention is use of j ; chemical catalysts. The reaction between ferrous ion and hydrogen peroxide i . : is one such preferred catalyst system. Other chemical catalysts are apparent j ^ I to those skilled in the art. / 1 ! A much preferred method to initiate these graft polymerizations is by ; use of eerie salts. It is believed that eerie ion reacts with pendant i: hydroxyl groups present in the substrate polymer. These hydroxyl groups ; I /950' (107r V ; j result from the reaction of epichlorohydrin with a ditertiary amine. The j product of this reaction is a polymer containing alternating quaternary ammonium units with hydroxypropylene units. j The radical resulting from the reaction of eerie ion with the hydroxyl ' groups is reactive toward vinyl monomers. Polymerization then proceeds, j adding further vinyl monomers and forming a new polymeric grafted chain one | end of which is covalently bonded to the substrate polymer. The result of this \ graft polymerization is the cationic polyquaternary ammonium graft copolymer J i of the present invention. 1 The reaction conditions can be varied over wide limits. The graft co- j polymers of the present invention can be made under conditions in which the i amounts, by weight, of the polyquaternary ammonium polymer (substrate) and ' the vinyl monomer (graft) are approximately equal. For example, the weight , ratio of substrate to vinyl monomer may be in the range of, say, ten to one to one to ten. Graft copolymers with molecular weights up to one million or more are produced by this process.

We have found that even higher molecular weight grafts are produced when the weight ratio of substrate to monomer is substantially lower than one-to-ten. For example, exceptionally high molecular weight graft copolymers are produced ! when the ratio of substrate to monomer is about one-to-fifty. Products made utilizing these ratios of reactants are quite effective flocculants If lower molecular weight products are desired, high weight ratios of j substrate to monomer are preferred. In addition, as taught by Nagy in U.S. j Patent 3,711,573, isopropanol or other chain transfer agents may be added to j i 1 the reaction mixture to reduce the molecular weight. ! 1 In general, it is desirable to have a final product which has a high polymer solids content. Container costs and shipping costs of low solids ■ j i j - 7 - I 2 0-7 930 content polymer solutions will increase the cost of the product and make it ! uneconomical even though the polymer properties may be superior. Water-soluble 1 polymers whose molecular weights are about one million or higher yield very j viscous aqueous solutions. The upper limit of polymer content in an aqueous i solution of a high molecular weight water-soluble polymer is less than ten j percent for molecular weights near one million. Solutions containing higher j polymer solids content are too viscous for use in many situations. j j i In a preferred embodiment of the process for making such high molecular j i i ii weight graft copolymers while retaining high total polymer solids content, il ii a small weight ratio of substrate polymer to monomer is employed. The total ii i ;; solids (substrate polymer plus monomer) is kept high, greater than ten percent.

, The reaction is initiated with eerie ion catalyst and polymerization proceeds.

■ To prevent gel formation, as the viscosity begins to build, additional low , molecular weight polyquaternary ammonium polymer (substrate) is added. Since i| the polymer content of the substrate solution can be twenty-five percent or \ j* higher, the total polymer solids content in the graft copolymer solution does ! not decrease. To further control the viscosity of the graft copolymer solution, ; isopropanol or other chain transfer agents may be added as well, either ; previous to, at the same time as, or subsequent to the addition of the added , polymer substrate solution.

Depending upon the amount of monomer in the initial charge and the amount ; of polyquaternary ammonium substrate polymer added in the second charge, the ' final polymer solids content may vary from five to twenty-five percent or higher. i : The conditions necessary for efficient graft polymerization are not j; critical. The pH of the solution should be acidic, in the range of one to i! ■ four pH units. The monomer need not be of high purity. For example, acryl- , amide is often supplied as a fifty percent aqueous solution containing copper i 20I950 i ion as a polymerization inhibitor. While some advantage is gained by removal Ii of the copper by ion-exchange in that somewhat higher molecular weights are i obtainable, this purification step is not critical or necessary. I Temperature is likewise not a critical parameter. Good grafting j: efficiency is obtained at ambient temperatures as well as at higher temperature | Removal of oxygen from the solution is often employed so that higher molecular | weight grafts are obtained, but this is not critical. Adquate polymerization ji efficiency and molecular weights are obtained when no effort is made to remove Ii ' oxygen.

It is well recognized in the art that when two or more monomers are co-polymerized, different properties are obtained when the relative concentrations ' of the monomers are different. The same holds true in graft copolymerizations. For certain applications, e. g., sludge dewatering, it has been found that high ratios of a cationic monomer, such as the dimethyl sulfate quaternization 1 product of dimethylaminoethyl methacrylate, to acrylamide will give a product having superior properties. For other applicants, e.g., water clarification, best results have been obtained when the grafted portion contains only small amounts of cationic monomer or even when the graft portion is completely non-ionic, i.e., a polyacrylamide graft.

In order to disclose the nature of the present invention still more . clearly, the following illustrative examples will be given. It is to be understood, however, that the invention is not to be limited to the specific conditions or details set forth in these examples except insofar as such , limitations are specified in the appended claims.

Parts as used herein and in the appended claims are parts by weight. *01950 (107) EXAMPLE 1 ! I This illustrates the preparation of a polyquaternary ammonium polymer j which is suitable as the substrate polymer in subsequent graft polymerizations. i | An epichlorohydrin-methylamine prepolymer was prepared by reacting 800 ; parts of a fifty percent aqueous methylamine solution with 2424 parts of epi-5 I chlorohydrin. The reaction was carried out at 35° C in 600 parts of n-propanol solvent. When the reaction was completed, 272 parts of concentrated sulfuric acid was added.

The polyquaternary ammonium polymer was then prepared by adding 2007 parts of water and 2275 parts of an aqueous solution containing 60 percent N,N,N',N'-10 ■ tetramethylethylenediamine. The mixture was heated to 70-75° C until the contents of the vessel became viscous, at which point the reactants were diluted with 7678 parts of water. The mixture was reheated and the reaction continued until the viscosity increased again. The polymerization reaction was stopped by adding 402 parts of sulfuric acid and 298 parts of water. The final 25 solution contained 25 percent by weight of polymeric solids. Over eighty percent of the nitrogen atoms in this polymer are quaternary nitrogen atoms.

EXAMPLE 2 This example describes a method for the preparation of a graft copolymer | of the present invention.

L j| Into a one liter glass reaction kettle fitted with an agitator, thermome- i ter, and nitrogen sparge tube was added 250 grams of the polyquaternary 1 ammonium polymer of Example 1, 100 grams of a 50 percent aqueous acrylamide 20T950 ! (107) | I | J solution, and 147 grams of deionized water. The solution was agitated and j purged with nitrogen to remove dissolved air. Into this mixture was added ! I 1 three milliliters of a catalyst solution consisting of 0.1 N eerie ammonium ! i | I nitrate in 1 N nitric acid. i A reaction occurred immediately. The temperature rose and the solution ; i i became very viscous in about five minutes. The reaction was allowed to continue ! I : for two hours. The resulting solution contained 22.5 percent of the poly- | ' quaternary ammonium-aery1amide graft copolymer wherein about 55.6 percent of i the graft copolymer arises from the substrate and about 44.4 percent of the ! I graft copolymer is polymerized acrylamide. j EXAMPLE 3 I This example describes the preparation of another polyquaternary ammonium , I polymer which is suitable as a substrate polymer in subsequent graft polymer- ! izations. i The ionene polymer, poly[hydroxyethylene(dimethyliminio)ethylene(dimethyl-! | iminio)methylene dichloridel was prepared by mixing 375 parts of an aqueous i solution containing 60 percent of N,N,N',N'-tetramethylethylenediamine(TMEDA) i and 4496 parts of muriatic acid (31.5 percent HC1) at a temperature below 50° C, } While the temperature was maintained at 40° - 50° c by cooling, 3588 parts of i epichlorohydrin were added. The mixture was further agitated for one-half j hour and then heated to 60° - 70° C at which temperature it was maintained while 3750 parts of additional aqueous solution of TMEDA were added. The concentra- j tion was adjusted to 60 percent polymer solids by distilling some of the water ! from the product. The molecular weight of the product is about 5,000. All of | the nitrogen atoms in this polymer are quaternary nitrogen atoms. i - - 11 - | 2°1950 (107) I , j; EXAMPLE 4 i i ; This illustrates a method for the preparation of graft copolymers using j| as the substrate the polymer of Example 3.

The general procedure of Example 2 was used except that 313 grams of i I water, 100 grams of a 50 percent acrylamide solution, and 84 grams of the ; polyquaternary ammonium polymer of Example 3 were added to the reaction kettle. i; ! Three milliliters of eerie catalyst were added and a viscous polymer solution was produced in a few minutes. Twenty-five minutes after the addition of the first three milliliters of catalyst, another three milliliters of catalyst were added. Twenty-five minutes after this second catalyst charge, another i 1 three milliliters of eerie catalyst were added. The resulting clear, viscous solution was approximately 20.1 percent polymer by weight wherein approximately half was grafted acrylamide and the remainder came from the substrate polyquaternary ammonium polymer of Example 3.

EXAMPLES 5-11 The general procedure of Example 2 was utilized except that 118.5 grams of water, 7.5 grams of isopropanol, 70 grams of acrylamide, and 250 grams of the polyquaternary polymer of Example 1 were agitated in the reaction flask. In addition to the acrylamide, the water-soluble vinyl addition monomers listed in Table 1 were utilized in separate preparations. In each case, 30 grams of the listed monomers were added. Three milliliters of eerie catalyst ! were added. In each case the temperature rose, and the solution became viscous indicating that a graft polymerization occurred. Additional eerie catalyst 7 95o (107) (three milliliters per each addition) was added. A total of 24 milliliters of catalyst was added to each except for Example 11 where only 12 milliliters were added. In this case, the solution was already extremely viscous.

Table 1 Comonomer Used with Acrylamide Example To Form Graft Copolymer Total Polymer Solids dimethylaminoethylmethacrylate metho- 24.3 sulfate (80% solution) 6 dimethylaminoethylmethacrylate 24.0 methylchloride (75% solution) j 7 dimethylaminopropylmethacrylamide 25.5 8 methacrylamidopropyltrimethyl ammonium 22.5 chloride (50% solution) 9 dimethyldiallylammonium chloride 25.5 N,N dimethylacrylamide 25.5 11 acrylic acid 26.1 EXAMPLE 12 j i The procedure of Example 2 was followed with the exception that the eerie i | catalyst was not used. Into the reaction kettle were added 250 g of the poly-| quaternary ammonium polymer of Example 1, 100 g of a 50 percent acrylamide j solution and 147 g of water. The pH was adjusted to 3.5 with 50 percent sodium I i | hydroxide.

I i ! Two milliliters of 0.35 percent hydrogen peroxide were added to the flask, j | i j quickly followed by two milliliters of a solution consisting of 0.1 M ferrous I ammonium sulfate in 1 M sulfuric acid. An immediate temperature rise occured, | accompanied by an increase in viscosity. The reaction was allowed to continue [ ' »50 for forty minutes after which 7.5 milliliters of isopropanol were added, followed by an additional charge of the catalyst, that is, two milliliters of 0.35 percent hydrogen peroxide and two milliliters of the ferrous solution. During the next two hours two more additions of the catalyst system (ferrous solution and ) were made. The resulting solution was similar in appear ance and composition to the product of Example 2, except that the product of this example contains slightly less polymer solids, 21.6 percent.

EXAMPLE 13 The following example describes the preparation of the polyquaternary ammonium graft copolymer of the present invention utilizing a combination of two catalyst systems.

The same procedure of Example 2 was followed. Into the reaction kettle was added 250 g of the polymer of Example 1, 100 g of a 50 percent acrylamide solution and 147 g of water. Three milliliters of the eerie catalyst were added. The temperature rose and the solution became viscous. Two hours after the reaction was initiated, 7.5 milliliters of isopropanol were added, followed by two milliliters of 0.35 percent hydrogen peroxide and two milliliters of the ferrous sulfate solution described in Example 12. A substantial amount of.un-reacted monomer was present following the first addition of the eerie catalyst since an immediate rise in temperature and a slight increase in viscosity occurred. Two more additions of two milliliters of each of the peroxide and ferrous solutions were made. No obvious reaction occurred following the last catalyst addition. The product of this Example was very similar in appearance and composition to the product of Example 12. 1 5 I EXAMPLE 14 | The following illustrates another method for preparation of the graft | copolymers of the present invention.

The general procedure of Example 2 was followed except that two reaction | kettles were charged with 100 g of a 50 percent acrylamide solution, 147-g of j water and 4 g of the polyquaternary ammonium polymer of Example 1. The ratio j of acrylamide to polyquaternary ammonium polymer was, therefore, 50 to 1 on a , solids basis. Three milliliters of eerie catalyst solution were added to each kettle. An immediate increase in temperature occurred in each solution, followed i \ by a rapid increase in viscosity. When the viscosity became so great that the |: solution began to climb the agitator shaft, 250 milliliters of water were added j' to the first kettle, Solution 14A, and 250 milliliters of the polyquaternary ammonium polymer of Example 1 were added to the second kettle, Solution 14B.

)■ | The reactions continued as evidenced by a slow climb in temperature and a noticeable increase in viscosity. Two hours after the initial charges of i. catalyst, an additional 300 milliliters of water were added to Solution 14A. i: Then to each solution 7.5 milliliters of isopropanol were added, followed by the addition of two milliliters of dilute hydrogen peroxide and two milliliters i | of the ferrous solution described in Example 12. A second charge of two milliliters of each of the ferrous solution and the peroxide solution was made to j each solution. The resulting solutions were approximately 6.3 percent polymer | solids for Solution 14A and 21.8 percent in Solution 14B.

!■ EXAMPLE 15 I, The polyquaternary ammonium graft polymers of this invention were tested ji for their effectiveness as flocculants in laboratory jar tests. Fifteen - 15 19 50 (107) J hundred milliliters of a 0.4 percent by weight suspension of Fuller's Earth j i (Kaolln)-jere added to each jar and agitated by paddles turning at 100 rpm. j J Varying quantities of the polymer solution to be tested were added and agitation j was coru-.iiiued for one minute after which agitation was stopped and the suspen- ! i sion allowed to settle for five minutes. Observations were made on the floccu- i j lation speed, i.e., the settling rate, as well as the final clarity of the j supernatant solution after five minutes._ ! i The flocculation speed was judged qualitatively and the polymers were j ranked in order of their flocculation speed. The clarity of the test solution | j was graded on a scale of 0 to 5 (0 means no settling and 5 signifies a clear j supernatant layer) after allowing for settling for five minutes. J Table 2 compares the properties of the graft copolymer prepared in ( ji Example 2 with two commercially available products both of which are used to j j: treat water, to remove suspended matter. Commercial product A is 25 percent i i: i !: by weight and commercial product B is 40 percent by weight of polymer solids. I !! ! j. A dilute solution (1500 ppm) of each polymeric product to be tested was first made up. Then 2, 4, or 8 milliliters of these dilute polymer solutions were added to the Kaolin suspension. The usage rate of each polymeric dilution product was, therefore, 2, 4, or 8 ppm. However, since the products differ on a percent solids basis, usage rate on a total polymer solids basis is, of course, different. i i ! ! - 16 - ' j j j *'019 50 (107) V Table 2 Clarity Rating at Usage Rate of 2 ppm 4 ppm 8 ppm Product of Example 2 (22.5 percent) 3.1 3.5 4.4 Commercial Product A (25 percent) 3.4 3.8 3.5 Commercial Product B (40 percent) 3.2 3.4 3.3 The product of Example 2 at each usage rate gave the fastest settling rate. It is seen in Table 2 that the two commercial products give good clarity at these usage rates with a maximum effect near 4 ppm. The product of Example 2, j in addition to having the fastest settling rates, gives substantially better clarity at somewhat higher usage rates, with no decrease in effectiveness at higher usage rates. Excellent effectiveness occurs over a wider range in usage rates.

| EXAMPLE 16 | i | This illustrates the effectiveness of the polyquaternary ammonium graft j copolymers in flocculating suspended matter when the grafted portion of the I polymeric product is a mixture of acrylamide and other water-soluble vinyl addition monomers, The procedure of Example 15 was followed. Polymer solutions tested were made from the products of Example 5 through 10, as well as Example 2. The results are shown in Table 3 below. 2 0 1 9 5 0 (107) Table 3 Clarity at Exam.;. ..a Comonomer Usage Rate of 2 ppm 5 ppm 2 Acrylamide alone 3.1 4.0 Dimethylaminoethyl 3.4 4.2 methacrylate methosulfate 6 Dimethylaminoethyl 3.1 4.0 methacrylate methylchloride 7 Dimethylaminopropyl 2.8 3.7 me thacrylamide 8 Methacrylamidiopropyl 2.9 3.8 trimethyl ammonium chloride 9 Dimethyldiallyl 2.8 3.8 ammonium chloride N,N Dimethylacrylamide 2.9 3.9 All of the graft copolymers in the table above show excellent flocculating properties.

EXAMPLE 17 This example illustrates the effectiveness of the graft copolymers of the present invention as flocculants for sewage sludge.

The apparatus consisted of No. 1 Buchner funnel positioned directly over a 250 ml graduated cylinder. A piece of filter cloth was cut to the same dimension as No. 1 filter paper and this filter cloth was placed in the Buchner funnel. This filter cloth was of the same type used in sludge dewatering presses. 201950 i ! | (107) j Five percent dilutions of the polymer solutions to be tested *;ere prepared. For each test 500 milliliters of sewage sludge (3.4 percent solids) were placed in a beaker. The desired amount of dilute polymer solution was placed in a second beaker. The sludge was then poured back and forth between the beakers three times to ensure complete mixing. The resulting mixture was then poured onto the filter cloth in the Buchner funnel.

; The solution was allowed to drain by gravity, i.e., no pressure or vacuum ! I was applied. The amount of liquid collected in the graduated cylinder was i recorded after 15; 30, 60 and 120 seconds. The better the sludge dewatering effectiveness of the polymer, the more liquid will be collected at any given time.

Two graft polymers were prepared for testing. The procedure of Example 6 was used to make Solution D. The reaction kettle was charged with 147 g of water, 250 g of the polyquaternary ammonium polymer of Example 1, 70 g of a 50 percent acrylamide solution, and 30 g of an 80 percent aqueous solution of dimethylaminoethylmethacrylatemethosulfate. Ceric catalyst was added nine times in three milliliter increments over the next four hours.

Solution E was prepared in a slightly larger scale. A. two-liter reaction kettle was charged with 828 g of water, 1000 g of the polyquaternary ammonium j i polymer of Example 1, 160 g of a 50 percent acrylamide solution and 40 g of isopropanol. Twelve milliliters of ceric catalyst were added.

Table 4 shows the sludge dewatering effectiveness of Solutions D and E compared to the effectiveness of a commercially available cationic polyacryl-amide polymer used in sludge dewatering operations. f <107) 20 1 950 Table 4 So.Vn ..'.an Volume of 5% Volume in Milliliters Xes " ■-rt Polymer Solution Added Collected After Milliliters sec. sec. 60 sec. 120 Solv- 'ion D 4 26 38 53 73 6 45 65 78 93 8 60 80 98 116 Solution E 4 27 50 65 6 50 65 83 100 8 55 75 93 105 Commercial 4 19 23 31 41 Cationic 6 32 45 60 75 Polyacrylamid e 8 52 70 85 101 The table demonstrates that graft copolymers of the present invention are effective in dewatering sewage sludge.

EXAMPLE 18 The polymeric mixtures of Example 15 of this invention were tested for their effectiveness in the retention of total solids in a paper pulp slurry using the method- described in Example 15 of New Zealand Patent Specification : 193787 which disclosure is hereby made a part of this application. ' Fractionation of the paper pulp slurry showed that the slurry contained j 27 percent fines. Percent fines retention could then be calculated once the | total solids retention and the percent fines in the original slurry were known. Table 5 shows that the polyquaternary ammonium acrylamide graft copolymer of I ! Example 2 is superior to the ungrafted polyquaternary ammonium polymer of 1 Example 1, a product which is presently used as a retention aid. ?0f95q (107) Table 5 Product Tested Control with no retention aid Example 1 Example 2 Use Rate Pounds per Ton of Pulp 0.75 1.50 2.50 .00 0.675 1.35 2.25 4.50 Percent Retention | of Fines i 59.6 65.3 69.6 71.5 71.2 67.3 69.2 74.3 81.8 EXAMPLE 19 This example illustrates the effectiveness of the graft copolymers of the present invention in increasing the dry strength of paper. i Handsheets were made and tested using a Scott Internal Bond Tester. Three: hundred grams of a 1.5 percent hardwood Kraft pulp which was refined to a Canadian Stand Freeness of 540 milliliters were added to 300 milliliters of water. The desired amount of diluted polymer solution was added to achieve the usage rates shown in Table 6 below. Solutions tested were the product of Example 2 wherein the grafted portion comprises acrylamide alone, the product 201 9$ 0 (107) of Example 7 vn&reixi tfca grafted portion comprises acrylamide and dimsihyl-aminoethylmethacrylaiie iir-if-.hyl chloride, and the product of Example 11 wherein the grafted portion r-.c«np .L;i2S acrylrmide and N,N-dimethylacrylamide. The graftj copolymers listed above ^er? compared to the product of Example 1, an i.j.grafted! polyquaternary ammonium polymer which is presently used by the paper Industry | to increase bond strength.

Table 6 Product Use Rate Increase in Percent Tested Pounds per ton of Pulp Scott Bond givength Example 1 10 14 Example 2 10 16 Example 7 10 24 Example 11 10 18 The graft copolymers of the present invention give increased bond strength and the presence of cationic comonomers in the grafted portion brings about the best improvement.

While particular embodiments of the invention have been described, it will be understood, of course, that the invention is not limited thereto since many modifications may be made thereof. It is, therefore, contemplated to cover by the appended claims any such modifications as fall within the true spirit and scope of the invention. (107) j 201 9E>0

Claims (16)

WHAT WE CLAIM IS: | j 1. A water-soluble high-molecular-weight quaternary ammonium graft copolymer j comprising as the substrate, a water-soluble polymeric quaternary ammonium | composition having a plurality of hydroxypropylene groups with the structure OH I
1. - A - CH2 - CH - CH2 - A -wherein A is a tertiary or quaternary nitrogen atom characterized in that the number of quaternary nitrogen atoms always exceeds the number of tertiary nitrogen atoms, and comprising as the grafted portion of the product a polymeric composition selected from the group consisting of water-soluble nonionic, anionic, and cationic vinyl addition polymers, and further characterized in that the amount of grafted vinyl addition polymer varies between one-tenth and one hundred times the amount of substrate polyquaternary ammonium polymer.
2. 2. The graft copolymer of Claim 1 wherein the vinyl-addition graft polymer is polyacrylamide.
3. 3. The graft copolymer of Claim 1 wherein the vinyl-addition graft polymer is a copolymer of acrylamide and acrylic acid.
4. 4. The graft copolymer of Claim 1 wherein the vinyl-addition graft polymer is a copolymer of acrylamide and the quaternization product of dimethylaminoethyl methacrylate with dimethyl sulfate.
5. 5. The graft copolymer of Claim 1 wherein the vinyl-addition graft polymer is a copolymer of acrylamide and the quaternization product of dimethylamino- j ethyl methacrylate with methyl chloride.
6. | 6. The graft copolymer of Claim 1 wherein the vinyl-addition graft polymer is a terpolymer of acrylamide, acrylic acid, and the quaternization product of dimethylaminoethyl methacrylate with dimethyl sulfate. (107) 201950
7. The graft copolymer of Claim 1 wherein the vinyl-addition graft polymer is a terpolymer of acrylamide, acrylic acid, and the quaternization product of dimethylamino ethyl methacrylate with methyl chloride.
8. The graft copolymer of Claim 1 wherein the substrate is a water-soluble polymeric quaternary ammonium composition derived from methylamine, epi- chlorohydrin and N,N,N',N'-tetramethylethylenediamine.
9. The graft copolymer of Claim 1 wherein the substrate is a water-soluble polymeric quaternary ammonium composition derived from epichlorohydrin and N,N,N'jN'-tetramethylethylenediamine.
10. The graft copolymer of Claim 1 wherein the substrate is a water-soluble polymeric quaternary ammonium composition derived from methylamine, epichlorohydrin, and N,N,N',N'-tetramethylethylenediamine and the vinyl addition graft polymer is polyacrylamide.
11. A method of increasing the rate of water removal from wet fibrous webs during the manufacture of paper and paperboard which comprises adding to the papermaking system the graft copolymer of Claim 1 in an amount sufficient to achieve the desired increase in the rate of water removal.
12. A method of improving the retention of the components of a papermaking furnish in the wet fibrous web during the nar.ufacture of paper and paper-board which comprises adding to the papermaking system the graft copolymer of Claim 1 in an amount sufficient to achieve the desired increase in retention.
13. A method of increasing the dry strength of paper and paperboard which comprises adding to the papermaking system the graft copolymer of Claim 1 in an amount sufficient to achieve the desired increase in strength. - 24 - (107) 201950
14. 14. A method of sizing paper or paperboard which comprises adding to the paper-making system the graft copolymer of Claim 1 in an amount sufficient to size said paper and paperboard.
15. 15. A method of flocculating solids from an aqueous system containing suspended or dissolved solids which comprises adding to said aqueous system as a flocculant the graft copolymer of Claim 1 in an amount sufficient to cause flocculation of said solids.
16. 16. A method of increasing the rate of water removal during the dewatering of wet sludges derived from municipal and industrial effluents which comprises adding to the wet sludges the graft copolymer of Claim 1 in an amount sufficient to increase the rate of water removal. WEST-WALKER, McCABE - 25 -