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
  • D21H17/41—Synthetic macromolecular compounds obtained by reactions only involving carbon-to-carbon unsaturated bonds containing ionic groups
  • D21H17/42—Synthetic macromolecular compounds obtained by reactions only involving carbon-to-carbon unsaturated bonds containing ionic groups anionic
  • D21H17/43—Carboxyl groups or derivatives thereof
• • 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
  • D21H17/41—Synthetic macromolecular compounds obtained by reactions only involving carbon-to-carbon unsaturated bonds containing ionic groups
  • D21H17/44—Synthetic macromolecular compounds obtained by reactions only involving carbon-to-carbon unsaturated bonds containing ionic groups cationic
  • D21H17/45—Nitrogen-containing groups
  • D21H17/455—Nitrogen-containing groups comprising tertiary amine or being at least partially quaternised

Definitions

• the present invention relates to a method for increasing paper strength comprising adding a certain paper strength agent to a pulp slurry during paper making. More particularly, it relates to a method for increasing paper strength comprising adding aluminum sulfate and a specific amphoteric copolymer as a paper strength agent to a pulp slurry.
• amphoteric copolymer an amphoteric water-soluble copolymer having a cationic functional group and an anionic functional group in one molecule
• amphoteric copolymer can very effectively increase paper strength and decreases pollution of wastewater, it is inten­sively studied.
• Japanese Patent Kokai Publica­tion Nos. 30913/1979, 60095/1983, 91897/1983 and 94697/1985 disclose methods for increasing paper strength which uses amphoteric copolymers comprising acrylamide, an ⁇ , ⁇ -unsatu­rated carboxylic acid (e.g. acrylic acid) and dialkylamino­alkyl acrylate and the like.
• An object of the present invention is to provide a method for increasing paper strength which can overcome the drawbacks and problems of the conventional methods using the amphoteric copolymer together with aluminum sulfate.
• the present invention provides a method for increasing paper strength comprising adding alu­minum sulfate and a paper strength-agent containing a copolymer comprising (a) 98 to 60 % by mole of repeating units derived from (meth)acrylamide, (b) 1 to 20 % by mole of repeating units derived from at least one compound selected from the group consisting of ⁇ , ⁇ -unsaturated mono­carboxylic acids and their salts and ⁇ , ⁇ -unsaturated di­carboxylic acids and their salts and (c) 1 to 20 % by mole of repeating units derived from a diallylamine derivative of the formula: wherein R1 and R2 are the same or different and hydrogen or methyl, R3 and R4 are the same or different and hydrogen or C1-C6 alkyl, and X ⁇ is an anion of an organic acid or an inorganic acid as an effective component to a pulp slurry and then making a sheet of paper from said slurry.
• (meth)acrylamide (a) acrylamide or meth­acrylamide is used as such or as a mixture thereof. Industrially, acrylamide is preferred.
• Examples of the compound (b) are unsaturated mono­carboxylic acids such as acrylic acid and methacrylic acid; unsaturated dicarboxylic acids such as maleic acid, fumaric acid and itaconic acid; and their alkali metal salts such as sodium salt and potassium salt or ammonium salt. A mixture of two or more of them may be used.
• diallylamine derivative (I) as the component (c) examples include organic or inorganic salts of secondary amines such as diallylamine and dimethallylamine; organic or inorganic salts of tertiary amines such as diallylmethyl­amine, diallylethylamine and diallylbutylamine; quarternary ammonium salts such as diallyldimethylammonium chloride, diallyldimethylammonium bromide, diallyldiethylammonium chloride, diallyldibutylammonium chloride and diallylmethyl­ethylammmonium chloride. A mixture of two or more of them may be used.
• the amphoteric copolymer comprises 98 to 60 % by mole, preferably 96 to 70 % by mole of the (meth)acrylamide (a), 1 to 20 % by mole, preferably 2 to 15 % by mole of the compound (b) and 1 to 20 % by mole, preferably 2 to 15 % by mole of the diallylamine derivative (I) as the component (c).
• the amphoteric copolymer may comprise units derived from a comonomer which is copolymerizable with the three components (a), (b) and (c) in such an amount that the paper strength-increasing effect and water-solubility of the amphoteric copolymer are not deteriorated.
• nonionic monomers such as (meth)acrylo­nitrile, methyl (meth)acrylate, hydroxyethyl (meth)acrylate, styrene and vinyl acetate; cationic monomers such as di­methylaminoethyl (meth)acrylate, dimethylaminopropyl(meth)­acrylamide and their quarternary derivatives; and bifunctio­nal monomers such as ethyleneglycol di(meth)acrylate and methylene bis(meth)acrylamide; and the like.
• amphoteric copolymer used according to the present invention can be prepared by copolymerizing these essential components and the optional components by any of conventional polymerization methods.
• the mono­mer components are copolymerized in water or a mixture of water and a water-soluble organic solvent in the presence of a polymerization initiator.
• any of conventio­nal ones may be used.
• examples of such initiator are per­sulfates such as ammonium persulfate and potassium persul­fate; azo compounds such as 2,2-diamidinyl-2,2-azopropane dihydrochloric acid and azobisisobutyronitrile; peroxides such as di-ter.-butylperoxide, cumene hydroperoxide and hydrogen peroxide; and the like.
• a known redox initiator such as a combination of potassium persulfate and sodium hydrogen sulfite or a tertiary amine can be used.
• a conventionally used chain transfer agent such as isopropanol and allylalcohol may be used.
• the polymerization is carried out at a temperature of from 10 to 100°C, preferably from 40 to 90°C for 1 to 20 hours.
• the polymerization may be carried out in the presence of oxygen, it is preferably carried out in an atmosphere of an inert gas such as nitrogen.
• the essential and optional monomer components may be added to a polymerization system all at once and then copolymerized, or one or more components are firstly added to the polymerization system and thereafter the rest of the components is added to the polymerization system continu­ously or by portions.
• amphoteric copolymers prepared as above those having a viscosity of 10 to 1,000 poise, particularly 30 to 300 poise (in a 15 % by weight aqueous solution) at 25°C are preferred.
• the viscosity of the amphoteric copolymer will influence the effects of the paper strength. When the viscosity is too small, such effect is decreased, and when it is too high, texture of paper is worsened. Therefore, the amphoteric copolymer having a viscosity out­side the range of from 10 to 1,000 poise are less preferred.
• Aluminum sulfate to be used according to the present invention is usually called as "Alum” and Al2(SO4)3 having 16 to 18 molecules of crystal water per molecule.
• paper is made by a per se conventional method which uses aluminum sulfate. Namely, to an aqueous dispersion of pulp, the paper strength agent of the present invention is added in an amount of 0.05 to 3 % by weight based on a dry weight of pulp and a sheet of paper is made from the slurry in the presence of aluminum sulfate.
• the amount of aluminum sulfate to be added is from 0.05 to 5 % by weight, preferably from 0.1 to 4 % by weight, more preferably from 0.2 to 1.5 % by weight based on the dry weight of pulp.
• the paper slurry may contain a conventional inter­nal sizing agent and/or a filler such as clay, talc and titanium oxide.
• diallylamine (2.9 g) as a component (c) was charged together with 36 % hydrochloric acid (3.0 g) and deionized water (178.2 g). pH of the mixture was adjusted to 4.5 with a 28 % aqueous solution of sodium hydroxide and air in the flask was purged by introducing nitrogen therein.
• the interior temperature was raised to 70°C and ammonium persulfate (0.45 g) was added. Thereafter, a mix­ture of a 50 % aqueous solution of acrylamide as a component (a) (61.8 g) and a 80 % aqueous solution of acrylic acid as a component (b) (3.2 g) was dropwise added over 2 hours while keeping the interior temperature at 70°C. After comp­letion of the addition of the mixture, the content in the flask was kept at 70°C for 4 hours.
• amphoteric copolymer prepared in the same manner as in Example 1 but using the components (a), (b) and (c) in amounts shown in Table 1, a amphoteric copolymer was prepared. Properties of the ampho­teric copolymers (Amphoteric copolymers B to J) prepared in Preparation Examples 2 to 10 are also shown in Table 1.
• the mixture was heated to 55°C, and then a mixture of ammonium persulfate (0.10 g) and sodium hydrogen sulfite (0.04 g) as polymerization initiators were added to the mixture. The resulting mixture was heated to 90°C over 60 minutes and kept at that temperature for 4 hours.
• a sheet of paper was made by Tappi standard type hand paper making machine, dehydrated and pressed followed by drying at 110°C for 4 minutes to produce a sheet of hand made paper of 125 ⁇ 2 g/m2 of basis weight.
• Bursting factor [(bursting strength/basis weight) ⁇ 100] and ring crush factor [(ring crush strength/basis weight) ⁇ 100] of each sheet of paper were measured accord­ing to JIS P-8112 and P-8126, respectively. The results are shown in Table 2.

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• Chemical & Material Sciences (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Paper (AREA)

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Cited By (8)

Citations (4)

• 1988
  • 1988-03-11 EP EP88103897A patent/EP0282081A1/de not_active Withdrawn
  • 1988-03-11 FI FI881146A patent/FI881146A/fi not_active IP Right Cessation
  • 1988-03-11 AU AU13029/88A patent/AU1302988A/en not_active Abandoned

Patent Citations (4)

Non-Patent Citations (1)

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