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
  • D21H17/33—Synthetic macromolecular compounds
  • D21H17/34—Synthetic macromolecular compounds obtained by reactions only involving carbon-to-carbon unsaturated bonds
  • D21H17/38—Synthetic macromolecular compounds obtained by reactions only involving carbon-to-carbon unsaturated bonds containing crosslinkable groups

Definitions

• chlorination of the acrylamide polymer can be accomplished without prior dehydration and is, in fact, more rapid than under dry conditions.
• the presence of water may be a necessary adjunct to the chlorination reaction.
• combinations of various N-chloroamide-containing polymers with fibers and the fibrous materials prepared therefrom and is directed particularly to a method for imparting wet strength to felted fibrous wet webs and materials made therefrom, such as paper, board, shaped pulp articles and the like.
• the invention also includes, as an additional important feature, the production of permanently strengthened paper, board and the like which retain their strength under wet alkaline conditions.
• the invention includes the improved fibers and fibrous products themselves, as well as methods of preparing these products, the N-chloroamide containing polymers which provide such wet strength and the method for their production as will hereinafter be more fully described.
• polymers of this class are substantive to fibers of material such as paper pulp or aqueous suspension; i.e., the polymer is selectively absorbed by the fibers from a dilute aqueous solution or dispersion thereof containing these fibers in amounts much greater than those corresponding to the concentration of polymer in the solution or to what would be contained in the water normally left in the sheet after forming.
• the above-described starting materials are known to exist in the form of both lower molecular weight polymers and relatively high molecular weight polymers, and either form may be used in practicing the present invention. It is 5 known, for example, that polyacrylamides of controlled molecular weights can be obtained by polymerizing acrylamide in water containing approximately 5 to 40% by volume of a water-miscible alcohol such as ethanol or isopropanol. By this procedure polymers having molecular weights as low as 2,000 or as high as 300,000 can be prepared. Similar procedures may be used in preparing the copolymers described above and the resulting molecular weights of the products are comparable, i.e.
• component x of Formulae I or II may be replaced by a non-ionic monomer as long as the resultant polymer is water-soluble.
• component x of Formulae I or II may be substituted by a non-ionic monomer such as those enumerated below, i.e. N-vinyl pyrrolidone.
• the polymer contains from about 1-20%, by weight, of the component x which may be replaced by the non-ionic monomer.
• Such polymers are produced by charging a starting copolymer of the non-ionic monomer and an acrylamide (or including a monomer Z) to the process described below.
• any polymer including neutral, cationic, natural or synthetic polymers which contain carboxylic acid amide groups, and preferably linear aliphatic chain polymers and coplymers wherein carboxylic acid amide groups are attached to carbon atoms of the polymer-forming chain, are reacted with any halogen, and preferably chlorine, at a temperature ranging from about -10°C to 80°C, preferably 0°C to 40°C.
• any halogen and preferably chlorine
• the polymer or copolymer is introduced in the reaction vessel in the form of a solution in water, or an emulsion of a polymer solution dispersed in an oil.
• the N-chloramide poly­mers can be applied to paper products by tub application methods if desired.
• preformed and completely or partially dried paper prepared from a chemical pulp such as sulfite pulp, sulfate pulp or a mechanical pulp such as groundwood or any mixture thereof may be immersed in or sprayed with a 1% to 5% aqueous solution or dispersion of the polymer and impregnated with about 50-100% thereof, based on the weight of the paper.
• the paper may then be heated for about 0.1 to 60 minutes at temperatures, whereby the paper is dried and polymer-bonding of the fibrils thereof is developed.
• the resulting paper has increased wet strength, and therefore this method is well suited for the impregnation of paper towels, absorbent tissue and the like as well as heavier stock such as kraft wrapping paper, bag paper board grades and the like.
• This addition may be made in the beater, stock chest, Jordan engine, fan pump, head box or at any other suitable point ahead of the papermaking wire or screen, followed by forming the treated fibers into a felted product on the wire or cylinder.
• the addition of the polymer of the present invention to the cellulosic paper stock ahead of the paper making wire or screen is necessarily employed when increased wet web strength is desired.
• the polymers of our invention are water-soluble, and they may be produced from copolymers of an acrylamide with cationic monomers, or terpolymers of an acrylamide and other non-ionic or cationic monomers as discussed above.
• the non-ionic comonomers may be selected from the group comprising: methacrylamine, N-methylacrylamide, N,N-dimethyla­crylamide, acrylonitrile, N-vinyl pyrrolidone, ethyl acrylate, vinyl acetate, methyl (meth) acrylate and the like.
• Other non-ionic comonomers which are known to those skilled in the art to be capable of free radical polymerization are also meant to be included as useful in this invention.
• the preferred water-soluble polymers prior to chlorination, are those polymers with the cationically charged monomers listed above, i.e. MAPTAC (methacrylamidopropyl trimethyl ammonium chloride), DADM (diallyldimethyl ammonium chloride), DMAPMA (dimethylaminopropyl methacrylamide), DMAEM (dimethylamino ethyl methacrylate), DMAEA (dimethylamino ethyl acrylate) and their quaternary salts.
• MAPTAC methacrylamidopropyl trimethyl ammonium chloride
• DADM diallyldimethyl ammonium chloride
• DMAPMA dimethylaminopropyl methacrylamide
• DMAEM dimethylamino ethyl methacrylate
• DMAEA dimethylamino ethyl acrylate
• standard viscosity means the viscosity of a 0.1% solution of the polymer in 1M NaCl in centipoises measured on a Brookfield Viscometer with UL adapter, speed 60 rpm, 25°C.
• a suitable reaction vessel To a suitable reaction vessel are charged 250 parts of a 10% aqueous polyacrylamide solution (approximate mole­cular weight: 267,000). This solution is diluted by adding 250 parts of water and then cooled to 0°C. Chlorine gas is charged into the solution with stirring for 20 minutes at the rate of 39.33 ml of chlorine gas per minute. (A total of 10 mole % of chlorine gas is charged). During the charge of the chlorine gas, the reaction vessel is immersed in an ice-water bath in order to keep the reaction temperature between 0°C and 1°C. After the completion of the addition of the chlorine, the reaction solution is poured slowly with stirring into 3,000 parts of methanol. The precipitated product is collected. The polymer contains 10 mole % of N-chloroamide functional group and is soluble in water.
• An 1% aqueous solution is prepared by dissolving 30 parts of a high molecular weight solid copolymer of poly­(acrylamide-MAPTAC) (molar ratio of acrylamide to MAPTAC is 90:10) is 2970 parts of water. The solution is sheared in a Waring blender to give a polymer of standard viscosity of 1.95 cps.
• the prepare N-chlorinated polymers with different N-chloro contents 500 parts of the above solution is used in each preparation.
• 500 parts of the solution is chlorinated by addition of chlorine gas at 25°C with stirring. For each chlorination, the rate of the addition of chlorine gas is so adjusted that the chlorination is completed in 5 minutes. The temperature of the reaction solution is kept below 30°C.
• the N-chloro content of each resin solution is analyzed by the active chlorine determination method.
• the mole % of N-chlorinated acrylamide unit for each resin is shown in Table I.
• An 1% aqueous solution is prepared by dissolving 95 parts of a high molecular weight emulsion containing 32.51% active solid of a copolymer of acrylamide and Q-DMAEM Metho­sulfate (the mole ratio of acrylamide to Q-DMAEM Methosulfate is 90:10) in a mixture of 1.7 parts of a commercially available emulsion breaker and 2991.75 parts of water.
• the solution is sheared in a Waring blender to give a polymer of standard viscosity of 1.8 cps.
• the process for Examples 2-7 is repeated.
• the polymers prepared and the mole % of N-chlorinated acrylamide unit for the resins are listed in Table II.
• a 20% solids copolymer of acrylamide-DADM of molecular weight of 180,000 is prepared by polymerization of 75 wt% of acrylamide and 25 wt% of DADM. 50 parts of the co­polymer is diluted with 150 parts of water in the reaction flask. 150 parts of n-heptane are added and the mixture is stirred and cooled externally to 0°C. 1598 c.c. of chlorine are charged into the reaction mixture in 15 minutes while the temperature of the reaction mixture is kept at 0°C to 2°C during the chlorination process by external cooling. The reaction mixture is then poured slowly into 2 liters of ethanol with agitation. The product polymer is precipitated. The precipitate is collected by filtration and dried. It is found by analysis that the product polymer contains 26.2 moles % of N-choloramide units.
• Example 14-18 The process of Examples 14-18 is repeated using 200 parts of an emulsion copolymer (38.3% solids) of an acrylamide-A-DMAEM methosulfate copolymer which contains 15 mole % of Q-DMAEM methosulfate and has a standard viscosity of 1.5 cps.
• the active chlorine content of the resulting polymers is shown in Table IV.
• the polymer of Example 1 is dissolved in water to make up a 2% aqueous solution.
• the aqueous solution is used in a tub-sizing test.
• Tub-sizing tests are carried out, first, at the natural pH of the solution (pH-3.0), and secondly after adjusting the pH of the solution to 6.0.
• the same solution after standing at 23°C for 2 days, is also used in tub-sizing test.
• the sheet is tub-sized in the solution and dried on a blotting paper, the % pick-up of the polymer solution is calculated.
• the sheet is dried on a drum drier for 1 minute at 240°F.
• the sheet is also given an additional cure of 5 minutes at 105°C.
• An alkali resistance test* is carried out on the treated sheet.
• a 1% aqueous solution of the polymer of Example 13 is prepared by dissolving 1 part of the solid polymer in 99 parts of water. 15 ml of the polymer solution is added to the pulp aliquot. The pulp aliquots are adjusted to the pH values shown in the following Table. The polymer solution added corresponds to 1.5% based on the dry weight of the fibers. The aliquots are gently stirred for 5 minutes or 10 minutes and then handsheets are made. The handsheet is dried on a drum drier for 1 minute at 240°F and the post-cured for 5 minutes at 220°F.
• the Wet Tensile expressed in Table VII is normalized to a basis weight of 50 lb. per 25" x 40"/500 ream.
• Example 2 is repeated except that MAPTAC is replaced by DADM. Again, excellent chlorination of the copolymer results.

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Citations (4)

• 1988
  • 1988-04-14 EP EP88105934A patent/EP0289823A3/de not_active Withdrawn
  • 1988-05-02 JP JP63107725A patent/JPS63288296A/ja active Pending
  • 1988-05-04 FI FI882076A patent/FI882076A/fi not_active Application Discontinuation
  • 1988-05-04 KR KR1019880005211A patent/KR880014196A/ko not_active Application Discontinuation

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