Classifications

• • D—TEXTILES; PAPER
  • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
  • D21H—PULP COMPOSITIONS; PREPARATION THEREOF NOT COVERED BY SUBCLASSES D21C OR D21D; IMPREGNATING OR COATING OF PAPER; TREATMENT OF FINISHED PAPER NOT COVERED BY CLASS B31 OR SUBCLASS D21G; PAPER NOT OTHERWISE PROVIDED FOR
  • D21H17/00—Non-fibrous material added to the pulp, characterised by its constitution; Paper-impregnating material characterised by its constitution
  • D21H17/20—Macromolecular organic compounds
  • D21H17/21—Macromolecular organic compounds of natural origin; Derivatives thereof
  • D21H17/24—Polysaccharides
• • D—TEXTILES; PAPER
  • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
  • D21H—PULP COMPOSITIONS; PREPARATION THEREOF NOT COVERED BY SUBCLASSES D21C OR D21D; IMPREGNATING OR COATING OF PAPER; TREATMENT OF FINISHED PAPER NOT COVERED BY CLASS B31 OR SUBCLASS D21G; PAPER NOT OTHERWISE PROVIDED FOR
  • D21H21/00—Non-fibrous material added to the pulp, characterised by its function, form or properties; Paper-impregnating or coating material, characterised by its function, form or properties
  • D21H21/14—Non-fibrous material added to the pulp, characterised by its function, form or properties; Paper-impregnating or coating material, characterised by its function, form or properties characterised by function or properties in or on the paper
  • D21H21/18—Reinforcing agents

Definitions

• the acid system is detrimental to ma- DRY STRENGTH ADDITIVES FOR PAPER chine parts and results in a paper sheet that becomes Merwin Frederick Hoover, Pittsburgh, and Gloria Di Marco Sinkovitz, Bridgeville, Pa., assignors to Calgon 5 Corporation, Pittsburgh, Pa.
• Paper products exhibiting markedly improved dry strength properties are produced by adding to the aqueous SUMMARY OF THE INVENTION cellulose dispersion, prior to sheet formation, novel, cationic graft copolymers of certain polymerizable acrylic
• P p P t have SUPeTIOI y and/or diallylic quaternary ammonium monomers and Strength P Pe when y eohtalnfrom 0 acrylamide grafted onto a dextran substrate.
• the dextran useful in our invention is a naturally- BACKGROUND OF THE INVENTION occurring polymer having a molecular weight between The present invention is directed to novel, cationic graft 0 and 0 of g
• the graft copolymers of our invention have two basic grafted onto a dextran substrate and their use as dry Components, 1) a dextran substrate and (2) an acrylic strength additives. Paper products prepared using these 01' diallylic polymerizable quaternary ammonium monograft copolymers as dry strength additives exhibit markedly mer.
• the graft copolymers consist of from 5 to 97.5 perimproved properties.
• dextran graft copolymers are t by Weight of the dextran substrate and the remaining incorporated into the paper product during the paper Pe ntag elng derived from one or more of the polymmaking process, preferably by adding them to the aqueous el'llahle quatelhar Y ammohlllm mP t I DCiuiosic pulp i i
• the preferred polymers of our invention have an addi- It is a well-accepted fact that it is desirable in many 40 tlohal eompeheht eompflsihg eel'ylamlde the etlhlvaleht applications to have paper products i h good d methacrylamide.
• the preferred compounds are graft costrength.
• the paper in- P y s f a a u a acrylamide dustry has a strong movement underway to reduce the one er a y dlallyhe Polymenlable q basis weight of paper, especially that of publication grade y ammohlllm mohomel's- The$e P y eOflSlSt of paper Reduced basis Weight in paper would correspondfrom 5 to 97. percent by welghtof the dextran substrate ingly reduce mailing cost.
• Dry strength aids are needed the remalhlhg Percentage being del'lved from e y for lighter weight paper because as the basis weight is amlde and the polymerizable quaternary ammonium lowered and the pigment loadings are increased to mainmonomer.
• the acrylamlde should be at least 5 percent thin opacity, the dry stl-ength of the Paper decreases By but no more than 75 percent of the remainder.
• the production costs are weight of the dextran substrate, from about 0.125 to about reduced since less pulp and power are needed to make an 71 Pereeht y Weight acrylamide and the r ma nder the equivalent sheet quaternaryammonium monomer.
• diallylic quaternary ammonium compounds which are useful in our invention are the di lower alkyl diallyl quaternary ammonium chlorides. They are represented by the formula:
• the useful acrylic aminimides are represented by the formula:
• R is H or CH R is a lower alkyl group of 1 to 4 carbon atoms, preferably CH R is an alkyl group of 1 to 4 carbon atoms or a mono or dihydroxy alkyl group of 1 to 4 carbon atoms, preferably R is CH;
• the useful acryloxyalkyl quaternary ammonium compounds are represented by the formula:
• m-Ni'Lm wnere R is H or CH R is a lower alkyl group of 1 to 4 carbon atoms; R, is H or a lower alkyl group of 1 to 4 carbon atoms; X is an anion selected from chlorine, bromine, and methyl sulfate; A is an alkyl group of 1 to 6 carbon atoms or a hydroxy alkyl group of 1 to 4 carbon atoms.
• the preferred compounds of this structure are dimethylaminoethyl methacrylate, 2 hydroxy 3-methacryloxy propyltrimethyl ammonium chloride, and 2- methacryloxyethyltrimethyl ammonium methyl sulfate.
• the useful acrylamidoalkyl quaternary ammonium compounds are represented by the formula:
• R R and X are as defined above;
• R is H or a linear or branched alkyl group of up to 5 carbon atoms and R is phenyl or a linear or branched alkyl group of up to 5 carbon atoms and where n is 1 or 2.
• ceric salt redox system It is known that certain ceric salts form a redox system when coupled with certain reducing agents such as alcohol, aldehydes, or amines. The reaction proceeds by a single electron transfer step, resulting in cerous ion and a partially oxidized reducing agent in free radical form; the free radical being formed on the dextran substrate backbone. If a monomer is present, polymerization will occur.
• EXAMPLE 1 A dextran graft copolymer of dimethyldiallyl ammonium chloride (DMDAAC) and acrylamide (AM) having a weight percentage of 40 percent dextran, 30 percent DMDAAC and 30 percent AM was prepared as follows. The reagents used were 20 grams of dextran having an average molecular weight of about 50 million, 22 grams of a 68.1 percent DMDAAC solution, 15 grams of acrylamide, 450 grams water, and 5 milliliters of a 0.1 normal ceric ammonium nitrate solution in one normal nitric acid.
• DMDAAC dimethyldiallyl ammonium chloride
• AM acrylamide
• EXAMPLE 2 A 40 percent dextran, 60 percent acrylamide graft copolymer was prepared in the following manner. Into a 500 milliliter flask equipped with a purge tube, thermometer, stirrer and condenser was added 120 grams of water and 5 grams of dextran having an average molecular weight of about 50 million. This dextran solution was purged with nitrogen for two hours at 30 C. while being stirred. Then 7.5 grams of acrylamide dissolved in 25 milliliters of water was added and the reaction mixture stirred for five minutes. Five milliliters of the ceric catalyst solution was then added. The catalyst solution was 0.1 normal ceric ammonium nitrate in one normal nitric acid. The mixture was then stirred for two hours at 30 C. The polymer was then precipitated from acetone and dried under vacuum for twenty-four hours.
• EXAMPLE 3 A 38.4 percent dextran, 30.8 percent acrylamide, 30.8 percent DMDAAC graft copolymer was prepared as follows. Into a 500 milliliter flask equipped with a purge tube, thermometer, stirrer and condenser was added 5 grams of dextran having an average molecular weight of about 50 million and milliliters of water. This dextrau solution was purged with nitr g n for one hour at 30 C. while being stirred. Then 4 grams of acrylamide dissolved in 25 milliliters of water and 5.5 grams of a 68.1 percent DMDAAC solution were added.
• EXAMPLE 4 A 40 percent dextran, 60 percent 2-hydroxy-3-methacryloxy propyl trimethyl ammonium chloride graft copolymer was prepared in the following manner. Into a 500 milliliter flask equipped with a purge tube, thermometer, stirrer and condenser was added 5 grams of dextran having an average molecular weight of about 50 million and 100 milliliters of water. This dextran solution was purged with nitrogen for one hour at 30 C. while being stirred. Then 7.5 grams of cationic monomer dissolved in 25 milliliters of water was added and the mixture stirred for five minutes. Five milliliters of the ceric catalyst solution was added (same as in Example I above). The mixture was then stirred for three hours at 30 C. The resulting polymer was precipitated from acetone and dried.
• EXAMPLE 5 A 20 percent dextran, 40 percent acrylamide, 40 percent DMDAAC graft copolymer was prepared in the following manner. Into a one liter, four-necked flask equipped with purge tube, thermometer, stirrer and condenser was added l0 grams of dextran haivng an average molecular weight of about 50 million and 391 grams of water. The dextran solution was purged with nitrogen for one hour at 30 C. while being stirred. At the same time, 20 grams of acrylamide was dissolved in 50 milliliters of water in a beaker. After the dextran solution was purged, 29.2 grams of a 68.1 percent DMDAAC solution was added and the reaction mixture stirred for five minutes.
• EXAMPLE 6 A 20 percent dextran, 60 percent acrylamide, 20 per-. cent DMDAAC graft copolymer was prepared in the following manner. Into a one liter, four-necked flask equipped with purge tube, thermometer, stirrer and condenser was added 16 grams of dextran having an average molecular weight of about 50 million and 385.4 milliliters of water. The dextran solution was purged with nitrogen for one hour at 30 C. After the dextran slurry was purged, 14.6 grams of a 68.1 percent DMDAAC solution was added and the reaction mixture stirred for five minutes. Then 30 grams of acrylamide dissolved in 50 milliliters of water was added and the reaction mixture stirred for another five minutes.
• EXAMPLE 7 A 40 percent dextran, 30 percent acrylamide, 30 percent DMDAAC graft polymer was prepared in the following manner.
• the dextran used had a molecular weight of about 20,000.
• Into a one liter, four-necked flask equipped with purge tube, thermometer, stirrer and condenser was added 20 grams of dextran and 390 milliliters of water. The resulting solution was purged with nitrogen for one hour at 30 C. After the purge, 24 grams of a 62.5 percent DMDAAC solution was added and the reaction mixture stirred for five minutes. Then 15 grams of acrylamide predissolved in 50 milliliters of water was added and the reaction mixture stirred for another five minutes. Five milliliters of the ceric catalyst solution (same as in Example 1) was added and the reaction mixture stirred for three hours at 30 C. The resulting polymer was precipitated from acetone and dried.
• EXAMPLE 8 A 40 percent dextran, 30 percent acrylamide, 30 percent DMDAAC graft copolymer was prepared using the same procedure as Example 7. However, the dextran used in this example had a molecular weight of about 273,000.
• EXAMPLE 9 A 40 percent dextran, 30 percent acrylamide, 30 percent 1,1-dimethyl-1-(2-hydroxy propyl) amine methacrylamide graft copolymer was prepared as follows. Into a one liter flask equipped with a purge tube, thermometer, stirrer and condenser was added 20 grams of dextran and 400 milliliters of water. This dextran solution was purged with nitrogen for one hour at 30 C. Then 15 grams of the aminimide dissolved in 25 m-ililliters of water was added and the mixture stirred for 15 minutes. Then 15 grams of acrylamide dissolved in 25 milliliters of water was added and the mixture stirred for an additional five minutes. After this, 5 milliliters of the ceric catalyst soluiton was added (same as in Example 1) and the reaction mixture stirred for three hours at 30 C. The resulting polymer was precipitated from acetone and oven dried.
• the graft copolymers of our invention consist of from 5 to 97.5 percent by weight of the dextran substrate and the remaining percentage being one or more of the monomers mentioned above.
• dextran graft copolymers of our invention were evaluated for their dry strength in alkaline media and also in acidic media.
• the polymers were also evaluated at various feed rates ranging from 0.25 percent to about 1 percent by weight based on the weight of the dry pulp.
• the polymers were evaluated by preparing a series of hand sheets on a Noble Wood machine using the various additives. The hand sheets were then conditioned at 50 percent RH for a minimum of twenty-four hours at 70 F. and then tested for burst and tensile strength. The strength values were reported as a percent increase over the control. The control was a hand sheet prepared under similar conditions except no dry strength additives were employed.
• the pulp stock used in preparing the hand sheets was bleached, hardwood sulfite pulp. The freeness was 650 cc. 'Schopper Reigler. When using acid medium, 2 per- .cent alum was also employed. However, when using alkaline medium, no additional additives other than the dry strength compound were used.
• the hand sheets prepared had a sheet weight of about three grams per sheet, which is approximately equivalent to forty-five pounds per 3,000 ft.
• the dry strength compounds were added at the headbox and mixed there for three minutes. When running under acid media, the headbox and sheet mold pH was adjusted to 4.5 with 0.5 NH SO When running under alkaline conditions, they were left unadjusted, which was a pH of from 7 to 9.
• Table 1 illustrates the effectiveness of the graft copolymers compared to dextran alone and a physical mixture of dextran and polymer.
• the compositions of the copolymers are given in weight percentages.
• the percent feed rate for Table 1 was 1 percent by weight based on weight of the dry pulp and the results are fo alkaline pH.
• ammonium chloride graft polymer ammonium chloride graft polymer.
• Table 2 illustrates the results of various feed rates for a 40 percent dextran/3O percent acrylamide/30 percent DMDAAC graft copolymer. In addition, this table illustrates that our graft copolymers are effective in acidic and alkaline systems.
• the paper of the present invention generally is prepared by forming an aqueous suspension of paper making cellulosic fibers, adding to said suspension a dry strength additive and any other desirable additive, sheeting the fibers to form a cellulosic web and heating the web until dry to form the paper.
• the dry strength additives of the present invention may be added to the cellulosic pulp suspension in amounts ranging from 0.1 to 5.0 percent by weight based on the dry weight of the cellulosic fibers. Below 0.1 percent, no appreciable effect on the paper is noticeable and the use of concentrations in the neighborhood of 5 percent is generally an overtreatment. The preferred range is from 0.2 to 1.0 percent.
• the dry strength additives of our invention are effective within the pH range of about 3.5 to 9 and in the concentration range mentioned above.
• the polymers of our invention may be added at any convenient point in the paper making process so long as they are added after the fan pump.
• they may be added as a dry powder or an aqueous solution.
• the use of an aqueous solution is preferred since it in sures a more uniform mixture of the additive and paper fibers.
• the ad t es are substantially non-thermosetting and hence need not be subjected to any critical drying conditions. Therefore, the invention contemplates that the paper will be produced by dryingon rolls in the normal range of 250 F.
• dry strength additives of our invention are also compatible with most of the other commonly employed materials used in the paper formation.
• they are compatible with rosin and the other common sizing agents, alum, the pigments such as clay, CaCO and TiO and the basically used dyes.
• a graft copolymer comprising from 5 to 97.5 percent by weight of a dextran substrate and the remainder derived from one or more polymerizable acrylic or diallylic quaternary ammonium monomers.
• a graft copolymer comprising from 5 to 97.5 percent by Weight of a dextran substrate, from 0.125 to 71 percent by weight acrylamide and the remainder derived from one or more polymerizable acrylic or diallylic quaternary ammonium monomers.
• R is hydrogen or an alkyl group of 1 to 4 carbon atoms
• R is H or CH
• R is selected from alkyl groups of 1 to 4 carbon atoms
• R is selected from alkyl groups of 1 to 4 carbon atoms, mono-hydroxy-alkyl groups of l to 4 carbon atoms, and dihydroxy alkyl groups of l to 4 carbon atoms
• Y is O or -NH
• A is an alkyl group of l to 6 carbon atoms or a hydroxyalkyl group of l to 4 carbon atoms
• X- is an anion selected from chlorine, bromine, and methyl sulfate.
• a graft copolymer as in claim 2 wherein the polymerizable quaternary ammonium monomer has the formula:
• n 1 or 2 and X- is an anion selected from chlorine, bromine, and methyl sulfate.
• An improved process for making paper having dry strength comprising forming an aqueous suspension of paper making cellulosic fibers, adding to said suspension a dry strength additive, sheeting the fibers to form a web and heating the web until dry to form the paper, wherein the improvement comprises adding an effective amount as the dry strength additive a graft copolymer comprising from to 97.5 percent by weight of a dextran substrate and the remander derived from one or more polymerizable acrylic or diallylic quaternary ammonium monomers.
• An improved process for making paper having dry strength comprising forming an aqueous suspension of paper making cellulosic fibers, adding to said suspension a dry strength additive, sheeting the fibers to form a web and heating the web until dry to form the paper, wherein the improvement comprises adding an eflective amount as the dry strength additive a graft copolymer comprising from 5 to 97.5 percent by weight of a dextran substrate, from 0.125 to 7'1 percent by weight acrylamide and the remainder derived from one or more polymerizable acrylic or diallylic quaternary ammonium monomers.
• R is hydrogen or an alkyl group of 1 to 4 carbon atoms;
• R is H or 01-1
• R is selected from alkyl groups of 1 to 4 carbon atoms;
• R is selected from alkyl groups of 1 to 4 carbon atoms, mono-hydroxy-alkyl groups of 1 to 4 carbon atoms, and dihydroxy alkyl groups of 1 to 4 carbon atoms;
• Y is -O or -NH;
• A is an alkyl group of 1 to 6 carbon atoms or a hydroxyalkyl group of 1 to 4 carbon atoms and
• X is an anion selected from chlorine, bromine, and methyl sulfate.

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Cited By (11)

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• 1971
  • 1971-09-22 US US00182898A patent/US3734820A/en not_active Expired - Lifetime
• 1972
  • 1972-08-11 CA CA149,284A patent/CA987412A/en not_active Expired
  • 1972-09-22 JP JP47094715A patent/JPS4841009A/ja active Pending

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