JP2537038C - - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a paper strength enhancer having an excellent paper strength enhancing effect in a papermaking system in which a large amount of an electrolyte substance coexists. [Related Art] In recent years, forest resources, which are raw materials for paper, are lacking, and the use ratio of used paper is increasing as a substitute. When such waste paper is used as a raw material for making paper, various electrolyte substances are dissolved in papermaking water, and the papermaking water is circulated and used as the papermaking process is closed. May contain large amounts of electrolyte material. In some cases, seawater, river water containing a large amount of electrolyte substances, or industrial water must be used as papermaking water. [Problems to be Solved by the Invention] However, when making paper using water containing such a large amount of electrolyte substance, it is generally widely used as an active ingredient of a dry paper strength enhancer for increasing dry paper strength. When a paper strength enhancer containing a polyacrylamide-based polymer is used, there is a problem that a sufficient paper strength enhancement effect cannot be obtained. SUMMARY OF THE INVENTION An object of the present invention is to provide a paper-strengthening agent that exhibits an excellent strength-enhancing effect even in a papermaking system using water containing a large amount of an electrolyte substance. [Means for Solving the Problems] To solve the above problems, the present invention provides: (a) 0.5 to 10 mol% of a monomer represented by the following general formula [I]; (Wherein, R ₁ is H or CH ₃ , R ₂ and R ₃ each have 1 to 2 carbon atoms. To indicate (B) at least one member of the group consisting of α, β-unsaturated dicarboxylic acids and salts thereof
A water-soluble copolymer obtained from a monomer component containing 0.2 to 5 mol% of two monomers, and (c) 85 to 99.3 mol% of acrylamide and / or methacrylamide, as an active ingredient ; Paper strength agent, characterized in be used in actual. 2. 2. The paper-strengthening agent according to claim 1, wherein the monomer represented by the general formula [I] in (a) is represented by the following chemical formula [II]. In the above case, the α, β-unsaturated dicarboxylic acid in (b) is preferably itaconic acid. Next, the present invention will be described in detail. The paper strength enhancer of the present invention comprises a water-soluble copolymer obtained from a monomer component containing the above (a), (b) and (c) as an active ingredient. The monomer represented by the general formula [I] of the above (a) is an ester-based cationic monomer, and specific substances belonging to the general formula [I] include dimethylaminoethyl methacrylate. , Dimethylaminoethyl acrylate, dimethylaminopropyl acrylate, diethylaminoethyl acrylate, and the like. Among them, a quaternary product of dimethylaminoethyl methacrylate represented by the above chemical formula [II] with benzyl chloride is preferable. Examples of the monomer (b) include maleic acid, fumaric acid, itaconic acid, α, β-unsaturated dicarboxylic acids such as citraconic acid, and sodium and potassium salts thereof.
Examples thereof include ammonium salts. Of these, itaconic acid and salts thereof have the most excellent effects. Of course, these may be used in combination. In addition to the above (a) and (b), the acrylamide and / or methacrylamide of the above (c) is used as a copolymer component.In addition to these three components, a cationic monomer such as dimethylaminoethyl methacrylate is used. The water-soluble copolymer may be used in combination with the component (a) .In addition, a hydrophobic monomer such as styrene, acrylonitrile, or ethyl acrylate may be used in an amount that does not impair the water solubility of the water-soluble copolymer to be obtained. A monomer may be used as a copolymer component. In order to produce a water-soluble copolymer obtained from the monomer components containing (a), (b) and (c), these monomers and the other monomers described above as required are used. A known and commonly used chain transfer agent such as isopropyl alcohol, allyl alcohol, sodium allyl sulfonate and sodium hypophosphite is appropriately used in the charged aqueous solution to adjust the monomer concentration to 5 to 30% by weight and the polymerization start pH to 3 to 6. And adding a radical polymerization initiator such as ammonium persulfate, sodium persulfate or potassium persulfate, or a redox initiator in which these persulfates are combined with a reducing agent such as sodium bisulfite, in the presence of an inert gas. It is manufactured by heating and stirring at 35-95 ° C for 1-10 hours. The water-soluble copolymer thus obtained is 300 to 100% in a 15% by weight solution.
Those having a viscosity of 2,000 cps (25 ° C., Brookfield viscosity) are preferred, and those having a viscosity of 800 to 30,000 cps are particularly preferred. In the case of extremely low viscosity (low molecular weight) of less than 300 cps, a paper strength enhancer containing the water-soluble copolymer as an active ingredient is inferior in the strength of paper strength and extremely high viscosity of more than 100,000 cps. In the case of (high molecular weight), the water-soluble copolymer causes excessive coagulation and disturbs the formation of the paper-made paper. And other adverse effects. The amount of the monomer of the component (a) in obtaining the water-soluble copolymer obtained from the monomer component containing the components (a), (b), and (c) according to the present invention is 0.5 to 10 mol% is preferred. If the amount is less than 0.5 mol, the fixing ability of the water-soluble copolymer to the pulp is insufficient, and if it is more than 10 mol%, the copolymerization ratio of (meth) acrylamide which provides carbamoyl groups only decreases. In addition, since a large amount of hydrophobic groups due to the benzyl group of the component (a) are present, hydrogen bonding between the water-soluble copolymer and the cellulose fibers is inhibited, so that the paper strength is rather reduced. Further, at least one of the α, β-unsaturated dicarboxylic acid and the salt thereof of the component (b) is used.
Species are the cationic site of the copolymer and the like present in the paper strength agent containing the obtained water-soluble copolymer as an active ingredient, or aluminum ion and aluminum ion of aluminum sulfate (sulfate band), which is frequently used as a papermaking chemical. It provides an anion site for forming a bond, and its use amount is preferably 0.2 to 5 mol%, and if it is less than 0.2 mol%, it is insufficient to form this ionic bond, and if it is more than 5 mol%, it is insufficient. The strength enhancer using the obtained water-soluble copolymer disperses pulp, especially fine fibrous pulp, and tends to adversely affect the pulp yield and the like, which is not preferable. α, β-
Of the unsaturated dicarboxylic acids, itaconic acid is most preferred. The paper strength enhancer of the present invention containing a water-soluble copolymer obtained from the monomer component containing the above (a), (b) and (c) as an active ingredient is a pulp dry weight of an aqueous dispersion of pulp. And 0.05 to 4% by weight. The adding place may be any place where the pulp is well dispersed in water in the paper making process. Use of a known sizing agent, paper strength enhancer, drainage improver, or the like at the time of papermaking does not hinder at all. [Action] The water-soluble copolymer according to the present invention has both a cationic portion and an anionic portion,
The cation site forms an electrostatic ionic bond with pulp that is negatively charged, so that the pulp has excellent fixation power, and the copolymers form an ionic bond between the cation site and the anion site. When aluminum sulfate is used for the papermaking system, aluminum ions fixed to the pulp bind to the anion site of the water-soluble copolymer, and the amount of carbamoyl in the (meth) acrylamide component is further increased. It is considered that the ability of the base pulp to form hydrogen bonds with the cellulose fibers exhibits a paper strength enhancing effect. At this time, if a large amount of electrolyte substance is present in the papermaking system, the above-mentioned ionic bond is hindered, and the fixing of the water-soluble copolymer to the pulp by the ionic bond is hindered. It is considered that a strong benzyl group is easily adsorbed to the hydrophobic part of the cellulose fiber of the pulp, and thus the paper strength enhancing effect is exhibited. At this time, when the α, β-unsaturated dicarboxylic acid is used as the component (b), ionic bond with a cation site in the obtained water-soluble copolymers, or with aluminum ion when aluminum sulfate is used in combination. Since the ionic bond is further strengthened and the bifunctional acid, the copolymerization ratio in the water-soluble copolymer is α, β-
Since the same number of anion sites can be obtained even if the amount is less than that of the unsaturated monocarboxylic acid, the copolymerization ratio of the above-mentioned (meth) acrylamide capable of forming a hydrogen bond can be increased by a smaller amount. It is considered that the paper strength enhancing effect is better than using β-unsaturated monocarboxylic acid. An α, β-unsaturated monocalcenoic acid such as acrylic acid or methacrylic acid may be used in combination as long as the excellent performance is not impaired. [Examples] Examples and application examples of the paper strength enhancer of the present invention are shown below, but the present invention is not limited to these examples. In the following, “%” means “% by weight” unless otherwise specified. Example 1 663.1 g of deionized water, 243.2 g of a 50% aqueous acrylamide solution, 80 parts of β-methacryloyloxyethyldimethylbenzylammonium chloride were placed in a 1 l four-necked flask equipped with a stirrer, thermometer, reflux condenser and nitrogen gas inlet tube. 19.16 g% aqueous solution,
4.68 g of itaconic acid and 12.95 g of a 2% aqueous solution of sodium hypophosphite were charged.
After the pH was adjusted to 4.0 with a 15% aqueous sodium hydroxide solution, the temperature was raised to 60 ° C. under nitrogen gas introduction, and 4.11 g of a 5% aqueous ammonium persulfate solution was added to initiate the polymerization reaction. Thereafter, the temperature was kept at 75 ° C. for 3 hours to complete the polymerization reaction. The polymer thus obtained was a clear aqueous solution having a non-volatile content of 15.5%, a Brookfield viscosity of 7200 cps at 25 ° C and a pH of 4.3. This is designated as copolymer A. Examples 2 to 8 Polymerization reactions were carried out in the same manner as in Example 1 by mixing the constituent monomer components shown in Table 1 to obtain copolymer aqueous solutions B to H. In order to obtain the same viscosity, the amount of the chain transfer agent was appropriately changed. Table 1 shows the physical properties of the copolymers obtained in the examples. Each monomer a ₁ b ₁ b ₂ b ₃ c ₁ c _{2 in} Tables 1 and 2 (for a comparative example described later)
d ₁ d ₂ d ₃ is as follows. a ₁ ... β-methacryloyloxyethyldimethylbenzylammonium chloride (compound of the above formula [II]) b ₁・ ・ ・ Itaconic acid b ₂・ ・ ・ Maleic acid b ₃・ ・ ・ Acrylic acid c ₁・ ・ ・acrylamide c ₂ · · · methacrylamide d ₁ · · · dimethylaminoethylmethacrylate d ₂ · · · 4 grade product by CH ₃ Cl in the d ₁ (beta-methacryloyloxyethyl trimethyl ammonium click Roraido) d ₃ · · · dimethyl Aminopropylacrylamide Comparative Examples 1 to 7 According to the composition of the constituent monomer components shown in Table 2, a polymerization reaction was carried out in the same manner as in Example 1 to obtain copolymer aqueous solutions a to g. Comparative Example 8 using only the acrylic acid b ₃ in place of the component (b), in accordance with the formulation of constituent monomer component of the other components are described in Table 2, performs the same polymerization reaction as in Example 1, the copolymer An aqueous solution h was obtained. Also in the case of the above comparative example, the amount of the chain transfer agent was appropriately changed. Table 2 shows the physical properties of the copolymer obtained in Comparative Example. Application Example 1 Tap water was used as papermaking water in order to clarify the effect of the paper strength enhancer of the present invention in a papermaking system containing a large amount of electrolyte substance. 2.0% sulfuric acid band in 2.5% aqueous dispersion of 399 ml of waste corrugated cardboard (based on dry weight of pulp, the same applies hereinafter)
After the addition, 1.0% of each of the copolymers obtained in Examples and Comparative Examples was added. The pulp slurry was diluted to 0.33%, and paper was made (pH 5.0 at the time of paper making) with a hand making device manufactured by Noble & Wood, and then 110 ° C., 1 ° C. with a drum dryer.
After drying for .5 minutes, a handmade paper (I) having a basis weight of 82 ± 2 g / m ^{2 and} a handmade paper (II) having a basis weight of 165 ± 3 g / m ² were obtained. The obtained handmade paper was conditioned at 20 ° C and a relative humidity of 65% for 24 hours, and then the handmade paper (I) had a “specific burst strength” and the handmade paper (II) Measured "specific compressive strength" and "plane compressive strength". Table 3 shows the results. The measurement of physical properties in each application example was performed according to the following method. In the table, "no addition" is a case where the above copolymer was not added. Specific burst strength: ··· JIS P-8112 Specific compressive strength ··· JIS P-8126 Specific plane compressive strength ··· Japan Tappi Paper pulp test method No. 29-78 “Core for corrugated ball” In the “Test method for plane compressive strength”, the humidity was controlled in a constant temperature and humidity room at a relative humidity of 65% and a temperature of 20 ° C. for 24 hours after stepping, and the measurement was performed. Break length ··· JIS P-8113 From Table 3, it is clear that the paper strength enhancer of the present invention exhibits an excellent paper strength enhancing effect in a system containing a large amount of an electrolyte substance. Application Example 2 In order to clarify the effect of the paper-strength enhancer of the present invention in a system containing a large amount of electrolyte substance due to the progress of closed paper-making process, various salts are used as paper-making water (Note 1). Was prepared and used in the same manner as in Application Example 1 using 383 ml of CSF waste corrugated paper, and the measurement was performed. Table 4 shows the results. From the table, it is clear that the paper strength enhancer of the present invention exhibits an excellent paper strength enhancing effect even in a papermaking system in which a large amount of salt has accumulated. Note 1) Salt-containing tap water The following salts are contained in 10 liters of tap water. Na ₂ SO ₄ 6.8 g CaCl ₂ 5.0 g MgCl ₂ 1.7 g K ₂ SO ₄ 0.6 g Application Example 3 In order to clarify the effect of the paper-strength enhancer of the present invention in a papermaking system using unbleached kraft pulp, 532 ml of CSF was used. Dispersion (slurry pH 10.5, conductive Each copolymer was added in an amount of 0.4%. This pulp slurry was diluted to 0.33%, paper-made with a hand-making device manufactured by Noble & Wood (pH 8.0 during paper-making), dried at 110 ° C. for 1.5 minutes with a drum dryer, and weighed 75 ± 2 g. / m ² of hand-made paper
(I) and handmade paper (II) having a basis weight of 150 ± 2 g / m ² were obtained. The obtained handmade paper was conditioned at 20 ° C. and a relative humidity of 65% for 24 hours, and then the handmade paper (I) had a “break length” and the handmade paper (II) had a "Specific pressure planting strength" was measured. Table 5 shows the results. From the table, it is clear that the paper strength-enhancing agent of the present invention also exhibits an excellent paper strength-enhancing effect even in unbleached kraft pulp containing a large amount of lignin soda and the like. Application Example 4 In order to clarify the effect of the paper strength enhancer of the present invention on gypsum board base paper, pulp (Note 2) obtained from a gypsum board base paper manufacturer was used, and its 2.5% To the aqueous dispersion, 1.0% of a saponified rosin sizing agent (PFP manufactured by Dick Hercules KK) and 2.5% of a sulfate band were added, and then 0.3% of each of the copolymers obtained in Examples and Comparative Examples was added. Was. This pulp slurry was diluted to 0.33%, paper-made with a hand-making device manufactured by Noble & Wood (pH 5.5 during paper-making), and then dried at 110 ° C. for 1.5 minutes with a drum dryer to obtain a basis weight of 160 ± 2. g / m ² of handmade paper was obtained. The obtained handmade paper was conditioned at 20 ° C. and a relative humidity of 65% for 24 hours, and then “tear length” and “specific burst strength” were measured.
Table 6 shows the results. It is clear from the table that the paper strength enhancer of the present invention also exhibits an excellent paper strength enhancing effect on gypsum board base paper. (Note 2) The pulp is a mixture of used newspaper and magazine used paper (CSF 160 ml), and the properties of this pulp slurry are as follows. Application Example 5 In order to clarify the effect of the paper strength enhancer of the present invention in an actual system in which the papermaking process is closed, paper obtained from a paperboard manufacturing company near a city where closed processing has been advanced is described. 2.5 using recycled pulp (Note 3)
1.0% of a sulfuric acid band was added to the aqueous dispersion, and then 0.4% of each of the copolymers obtained in Examples and Comparative Examples was added. This pulp slurry was diluted to 0.33%, paper-made with a hand-making device manufactured by Noble & Wood (pH 4.5 during paper-making), and then dried with a drum drier at 110 ° C. for 1.5 minutes to obtain a basis weight of 80 ± 2. g / m ² of hand-made paper
(I) and handmade paper (II) having a basis weight of 160 ± 2 g / m ² were obtained. The resulting handmade paper is 20 ° C,
After conditioning for 24 hours under the condition of a relative humidity of 65%, "specific burst strength" was measured for handmade paper (I) and "specific compressive strength" was measured for handmade paper (II). Table 7 shows the results. It is clear from the table that the paper-strengthening agent of the present invention shows an excellent paper-strengthening effect even when a pulp containing a large amount of an electrolyte substance used in a papermaking company is used. Note 3) The pulp is waste corrugated paper (CSF 416 ml), and the properties of this pulp slurry are as follows. From the above Tables 3 to 7, it is clear that the paper strength enhancers of the examples of the present invention show an excellent paper strength enhancing effect in a system containing a large amount of an electrolyte substance, and acrylic acid is used instead of the component (b). It can be seen that this is superior to the case of using. [Effect of the Invention] The paper strength enhancer of the present invention comprises a water-soluble copolymer obtained from a monomer component containing the above (a) to (c) as an active ingredient , and at least 770 An excellent paper strength enhancing effect can be provided in a papermaking system containing the electrolyte substance of (a), and the water-soluble property similarly obtained by using, for example, methyl chloride as the quaternizing agent of the component (a).
Copolymer, or (b) in place of the component alpha, can exhibit an excellent paper strength enhancing effect than if an active ingredient a water-soluble copolymer obtained analogously using β- unsaturated monocarboxylic acid . [Table 1] [Table 2] [Table 3] [Table 4] [Table 5] [Table 6] [Table 7]

Claims (1)

[Claims] 1. (a) 0.5 to 10 mol% of a monomer represented by the following general formula [I], (Wherein, R ₁ is H or CH ₃ , R ₂ and R ₃ each have 1 to 2 carbon atoms. To indicate (B) at least one member of the group consisting of α, β-unsaturated dicarboxylic acids and salts thereof
A water-soluble copolymer obtained from a monomer component containing 0.2 to 5 mol% of two monomers, and (c) 85 to 99.3 mol% of acrylamide and / or methacrylamide, as an active ingredient ; Paper strength agent, characterized in be used in actual. 2. 2. The potentiator according to claim 1, wherein the monomer represented by the general formula [I] in (a) is represented by the following chemical formula [II]. 3. 3. The paper-strengthening agent according to claim 1, wherein the α, β-unsaturated dicarboxylic acid of (b) is itaconic acid.