CN112601860B

CN112601860B - Additive for papermaking, paper and method for producing paper

Info

Publication number: CN112601860B
Application number: CN201980055477.0A
Authority: CN
Inventors: 山本琢二; 信国茂树; 岩城直陶; 茨木英夫; 吉谷孝治
Original assignee: Seiko PMC Corp
Current assignee: Seiko PMC Corp
Priority date: 2018-08-31
Filing date: 2019-08-28
Publication date: 2023-10-03
Anticipated expiration: 2039-08-28
Also published as: JP7081674B2; JPWO2020045514A1; KR20210049104A; CN112601860A; WO2020045514A1; AU2019332388A1; AU2019332388B2

Abstract

The invention provides a polyacrylamide additive for papermaking with excellent paper strength enhancing effect, paper using the additive for papermaking, and a method for manufacturing paper using the additive for papermaking. An additive for papermaking, comprising an amphoteric polyacrylamide comprising (A) (meth) acrylamide, (B) (meth) allylsulfonic acid, (C) an anionic vinyl monomer having a carboxyl group, and (D) a cationic vinyl monomer having a quaternary ammonium as a copolymerization component, wherein the ratio of the anionic equivalent to the cationic equivalent of the amphoteric polyacrylamide is 0.05 or more and 1.7 or less, the octanol/water partition coefficient of the amphoteric polyacrylamide is-1.44 or more and-0.60 or less, and the surface tension of the amphoteric polyacrylamide is 66mN/m or more and less than 74mN/m.

Description

Additive for papermaking, paper and method for producing paper

Technical Field

The present invention relates to a papermaking additive excellent in paper strength enhancing effect, a paper containing the papermaking additive, and a method for producing the paper.

Background

In order to improve productivity and paper strength, various papermaking additives including polyacrylamide-based paper strength agents have been used in the production of paper.

As a polyacrylamide paper agent, for example, there are proposed: a paper strength enhancer which is an aqueous acrylamide polymer solution having a low viscosity despite having a high concentration and a high molecular weight and is excellent in paper strength such as burst strength and Z-axis strength and water drainage (see patent document 1); a paper strength enhancer comprising an acrylamide polymer obtained by polymerizing a polymerizable component comprising (meth) acrylamide, a quaternary ammonium monomer and (meth) allylsulfonate and containing no nitrogen-containing crosslinkable monomer and a tertiary amino monomer (see patent document 2).

In recent years, from the viewpoint of environmental concerns and improvement of handleability, the use of old paper stock and water saving (white water recycling) have been advanced in the production of paper, or from the reduction of aluminum sulfate in neutral papermaking to the absence of aluminum sulfate, and as a result, problems of paper quality degradation have arisen due to an increase in ash content in paper stock, a high conductivity of the papermaking system, and the like.

However, in the above prior art, when only a small amount of an aluminum compound such as aluminum sulfate or polyaluminum chloride (Polyaluminium chloride, PAC) as a fixing aid of a paper strength enhancer is added to a pulp slurry, a system of aluminum-free papermaking is used; or a highly conductive papermaking system with a high white water recirculation rate for water saving or a papermaking system with a limited paper strengthening effect even if a paper strengthening agent is added to the pulp slurry, a sufficiently satisfactory paper strengthening effect cannot be obtained.

Prior art literature

Patent literature

Patent document 1: japanese patent laid-open No. 08-067715

Patent document 2: japanese patent publication No. 6060314 (International publication No. WO 2016/092965)

Disclosure of Invention

Problems to be solved by the invention

The invention provides a polyacrylamide additive for papermaking, paper containing the additive for papermaking and a method for producing paper using the additive for papermaking.

Technical means for solving the problems

The present inventors have made an effort to study and as a result found that: by using a specific additive for papermaking of polyacrylamide, a paper having satisfactory paper strength can be obtained even under the papermaking conditions (old paper use, white water recycle, no aluminizing sulfate).

That is, the present invention as means for solving the above problems is:

1 > an additive for papermaking comprising (A) (meth) acrylamide, (B) (meth) allylsulfonic acid ((meth) allylsulfonic acid), (C) anionic vinyl monomer having carboxyl group (anionic vinyl monomer), (D) cationic vinyl monomer (cationic vinyl monomer) having quaternary ammonium (quaternary ammonium) as a copolymerization component, and characterized in that the ratio of the equivalent amount of anions to the equivalent amount of cations of the amphoteric polyacrylamide is 0.05 or more and 1.7 or less, the octanol (octanol)/water distribution coefficient (water partition coefficient) of the amphoteric polyacrylamide is-1.44 or more and-0.60 or less, the surface tension of the amphoteric polyacrylamide is 66mN/m or more and less than 74mN/m,

The papermaking additive according to < 2 > and < 1 >, wherein the amphoteric polyacrylamide has a peak top molecular weight (peak top molecular weight) Mp of 100 to 500 tens of thousands, a molecular weight distribution Mw/Mn of 2.5 to 8.0, a ratio Mp/V of the peak top molecular weight Mp to a viscosity V of a 20 mass% aqueous solution (25 ℃) of the papermaking additive of 200 to 800,

< 3 > a paper comprising the papermaking additive according to the above < 1 > or < 2 >,

a method for producing paper, characterized by adding 0 to 0.3 mass% of an aluminum compound (aluminum compound) to the dry mass of the pulp in terms of alumina to the pulp slurry using the papermaking additive described in < 1 > or < 2 >, and papermaking (papermaking) at a papermaking pH of 5.0 to 8.5,

a method for producing a paper according to < 5 > or < 4 > wherein the paper has a conductivity exceeding 300mS/m.

ADVANTAGEOUS EFFECTS OF INVENTION

According to the present invention, even under the current paper-making sheet, paper excellent in paper strength can be provided.

Detailed Description

The amphoteric polyacrylamide contained in the papermaking additive of the present invention is obtained by copolymerizing monomers comprising (A) (meth) acrylamide, (B) (meth) allylsulfonic acid, (C) an anionic vinyl monomer having a carboxyl group, and (D) a cationic vinyl monomer having a quaternary ammonium as a copolymerization component. The amphoteric polyacrylamide is preferably present in an amount of 90 mass% to 100 mass% based on the total solid content of the papermaking additive.

(A) The (meth) acrylamide is acrylamide or methacrylamide, and can be used alone or in combination.

(B) The (methyl) allylsulfonic acid is at least one selected from alkali metal salts or ammonium salts such as sodium salt and potassium salt of allylsulfonic acid and methallylsulfonic acid. Among these, sodium methallylsulfonate is preferable.

The anionic vinyl monomer having a carboxyl group may be any anionic vinyl monomer having one or more carboxyl groups. For example, an alkali metal salt or ammonium salt such as an unsaturated monocarboxylic acid, an unsaturated dicarboxylic acid, an unsaturated tricarboxylic acid, an unsaturated tetracarboxylic acid, and sodium salts and potassium salts thereof may be used singly or in combination of two or more. Among these, in terms of the paper strength enhancing effect and economy, alkali metal salts or ammonium salts such as unsaturated monocarboxylic acids, unsaturated dicarboxylic acids, and sodium salts and potassium salts thereof are preferable.

Examples of the unsaturated monocarboxylic acid include: acrylic acid, methacrylic acid, 2- (meth) acrylamide-N-glycollic acid, N-acryloylglycine, 3-acrylamidopropionic acid, 4-acrylamidobutyric acid, and the like.

Examples of the unsaturated dicarboxylic acid include: maleic acid, fumaric acid, itaconic acid, citraconic acid, and the like.

Among the anionic vinyl monomers having a carboxyl group, the (C) is more preferably an alkali metal salt or ammonium salt such as sodium salt or potassium salt of acrylic acid, 2-acrylamide-N-glycollic acid or itaconic acid.

The cationic vinyl monomer having quaternary ammonium (D) may be a vinyl monomer obtained by reacting a vinyl monomer having a tertiary amino group with a quaternizing agent, or a diallyl dialkyl ammonium quaternary salt. As the quaternizing agent, there may be mentioned: alkyl halides (methyl chloride), such as methyl chloride (methyl bromide); halogenated aromatic hydrocarbons (aryl haloides) such as benzyl chloride (benzyl chloride) and benzyl bromide (benzyl bromide); dimethyl sulfate, diethyl sulfate, epichlorohydrin, 3-chloro-2-hydroxypropyl trimethyl ammonium chloride, glycidyl trialkyl ammonium chloride, and the like.

Examples of the cationic vinyl monomer having a quaternary ammonium group (D) include: dimethylaminoethyl acrylate methyl chloride quaternary salt, dimethylaminoethyl acrylate methyl sulfate quaternary salt, dimethylaminoethyl acrylate benzyl chloride quaternary salt, dimethylaminoethyl methacrylate methyl sulfate quaternary salt, dimethylaminoethyl methacrylate benzyl chloride quaternary salt, dimethylaminopropyl acrylamide methyl sulfate quaternary salt, dimethylaminopropyl acrylamide benzyl chloride quaternary salt, dimethylaminopropyl methacrylamide methyl sulfate quaternary salt, dimethylaminopropyl methacrylamide benzyl chloride quaternary salt, dimethylaminopropyl acrylamide 3-chloro-2-hydroxypropyl trimethylammonium chloride quaternary salt (N- (3-Acylamidopropyl) -N, N ', N ' -pentamethyl-N, N ' - (2-hydroxy-propyl-1, 3-diyl) diammonium dichloride), diallyl dimethyl ammonium chloride, diallyl diethyl ammonium chloride.

The cationic vinyl monomer (D) having a quaternary ammonium may be used singly or in combination of two or more.

The amphoteric polyacrylamide contained in the papermaking additive of the present invention is preferably: the proportion of the components (A) to (D) constituting the amphoteric polyacrylamide is

(A) 62 mol percent to 99.2 mol percent of (methyl) acrylamide

(B) 0.1 to 3 mol% of (methyl) allylsulfonic acid

(C) 0.2 to 15 mol% of anionic vinyl monomer having carboxyl group

(D) 0.5 to 20 mol% of a cationic vinyl monomer having a quaternary ammonium group.

The amphoteric polyacrylamide contained in the papermaking additive of the present invention may be used by adding other monomers in addition to the above-mentioned (a) to (D) within a range that does not inhibit the effect of the present invention. Examples of the monomers other than the above (a) to (D) include: other anionic vinyl monomer (C '), other cationic vinyl monomer (D'), crosslinkable monomer (E), nonionic vinyl monomer (F).

Examples of the other anionic vinyl monomer (C') include: unsaturated sulfonic acids (excluding the (B) (meth) allylsulfonic acids), unsaturated phosphonic acids, and alkali metal salts or ammonium salts thereof such as sodium salts and potassium salts thereof. In place of a part of the anionic vinyl monomer (C) having a carboxyl group, another anionic vinyl monomer (C') may be used in an amount of preferably 10 mol% or less, more preferably 5 mol% or less.

As the unsaturated sulfonic acid, there may be mentioned: vinyl sulfonic acid, styrene sulfonic acid, 2-acrylamide-2-methylpropane sulfonic acid, and the like.

Examples of the unsaturated phosphonic acid include vinylphosphonic acid and α -phenylvinylphosphonic acid.

Examples of the other cationic vinyl monomer (D') include vinyl monomers having a tertiary amino group, a secondary amino group, and a primary amino group, such as dimethylaminoethyl (meth) acrylate, diethylaminoethyl (meth) acrylate, dimethylaminopropyl (meth) acrylamide, diethylaminopropyl (meth) acrylamide, alkyldiallylamine, diallylalkylamine, diallylamine, and allylamine, and salts of inorganic acids or organic acids such as hydrochloric acid, sulfuric acid, formic acid, acetic acid, and phosphoric acid. Other cationic vinyl monomers (D') may be used instead of a part of the cationic vinyl monomer (D) having quaternary ammonium.

Examples of the crosslinkable monomer (E) include: n-substituted (meth) acrylamides such as N, N-dimethyl (meth) acrylamide, N-methylolacrylamide, N' -methylenebis (meth) acrylamide, and the like; polyfunctional (meth) acrylates such as ethylene glycol di (meth) acrylate and triacrylate formal; divinyl esters such as divinyl adipate. One kind of these may be used alone, or two or more kinds may be used in combination. It is preferable to use 0.001 mol% to 2.0 mol% of a crosslinkable monomer (E) as a copolymerization component of the amphoteric polyacrylamide in place of a part of the components (A) to (D).

Examples of the nonionic vinyl monomer (F) include: (meth) acrylic acid esters, (meth) acrylonitrile, styrene derivatives, vinyl acetate, vinyl propionate, methyl vinyl ether, and the like. One kind of these may be used alone, or two or more kinds may be used in combination. The nonionic vinyl monomer (F) is preferably 10 mol% or less, more preferably 5 mol% or less, instead of a part of the components (a) to (D), as the copolymerization component of the amphoteric polyacrylamide.

The method for producing the amphoteric polyacrylamide is not particularly limited, and various methods known in the art can be used. For example, the monomer and water (optionally, an organic solvent may be used in combination) as a solvent are added to a reaction vessel including a stirrer and a thermometer under an inert gas atmosphere such as nitrogen, and the pH is adjusted by using an acid such as sulfuric acid or hydrochloric acid or a pH adjusting agent such as a base such as sodium hydroxide, potassium hydroxide or ammonium, if necessary. Then, a polymerization initiator is added to perform a reaction in a temperature range in which the reaction can be controlled, and the intended amphoteric polyacrylamide can be obtained. If necessary, the polymerization may be carried out while adding a part or all of the monomer, water, chain transfer agent, pH adjuster, and polymerization initiator dropwise to the reaction vessel. In terms of expanding the degree of freedom in the molecular structure design of the copolymer, it is preferable to split and/or drip the monomer for polymerization.

The polymerization initiator used in the present invention is not particularly limited, and a known polymerization initiator can be used. For example, it is possible to exemplify: persulfates such as sodium persulfate, potassium persulfate, and ammonium persulfate; peroxides such as hydrogen peroxide, benzoyl peroxide, t-butyl hydroperoxide, and di-t-butyl peroxide; bromates such as sodium bromate and potassium bromate; perborates such as sodium perborate, potassium perborate, ammonium perborate, etc.; percarbonate such as sodium percarbonate, potassium percarbonate and ammonium percarbonate; and perphosphates such as sodium superphosphate, potassium superphosphate and ammonium superphosphate. In this case, the polymerization initiator may be used alone, but may be used in combination with a reducing agent as a redox-type polymerization initiator.

As the reducing agent, there may be exemplified: organic amines such as sulfite, bisulfite, or N, N, N ', N ' -tetramethyl ethylenediamine, azo compounds such as 2,2' -azobis-2-amidinopropane hydrochloride, reducing sugars such as aldose, and the like. Azo compounds such as azobisisobutyronitrile, 2' -azobis-2-amidinopropane hydrochloride, 2' -azobis-2, 4-dimethylvaleronitrile, 4' -azobis-4-cyanovaleric acid and salts thereof can also be used. These reducing agents may be used in combination of two or more.

The amount of the polymerization initiator used in the polymerization is not particularly limited, but is usually 0.005 parts by mass or more and 5 parts by mass or less, preferably 0.01 parts by mass or more and 2.5 parts by mass or less, per 100 parts by mass of the polymerization component, in order to sufficiently carry out the polymerization reaction of the polymerization component.

The papermaking additive of the present invention is required to have a ratio of the equivalent amount of anions to the equivalent amount of cations of the amphoteric polyacrylamide contained in the additive of 0.05 to 1.7. Here, the ratio of the equal amount of anions to the equal amount of cations is a value obtained by dividing the total of the equal amounts of anions of all the monomers exhibiting anions constituting the amphoteric polyacrylamide by the total of the equal amounts of cations of all the monomers exhibiting cations. When the ratio of the equal amount of anions to the equal amount of cations in the amphoteric polyacrylamide is less than 0.05, the ionic bond site with the aluminum compound added to the pulp slurry or the aluminum compound in the used paper is small, and therefore, the fixation to the pulp fiber is difficult, and the paper strength enhancing effect is lowered.

When the ratio of the equivalent amount of anions to the equivalent amount of cations exceeds 1.7, the anionic groups are less likely to be bonded to the negatively charged pulp fibers or the anionic groups are likely to be intramolecular-neutralized with the cationic groups, and therefore, the pulp fibers are difficult to fix to the pulp fibers, and the paper strength enhancing effect is lowered.

The papermaking additive of the present invention needs to have an octanol/water partition coefficient (hereinafter, sometimes referred to as LogP (Poly)) of-1.44 or more and-0.60 or less of the amphoteric polyacrylamide contained. Here, the octanol/water partition coefficient (LogP) can be determined using the Howard's method (journal of pharmaceutical science (J. Of Pharmaceutical Sciences) Vol84, no.1 1995). The octanol/water partition coefficient (LogP (Poly)) of the amphoteric polyacrylamide can be calculated by the Howard method, and the octanol/water partition coefficient (LogP) of each copolymerized component of the amphoteric polyacrylamide can be calculated by calculation, and the sum of the obtained values multiplied by the respective mole fractions of the copolymerized components can be calculated.

The octanol/water partition coefficient (LogP) of each copolymer component was determined by the following calculation formula.

LogP＝Σ(fi×ni)+Σ(cj×nj)+0.229

Here, fi and cj are segment constants and correction coefficients corresponding to the respective copolymerization components, respectively, and examples are shown in table 1. The term "fragment" refers to a product obtained by arbitrarily dividing a chemical structure.

TABLE 1

* More than two cases

From table 1, for example, acrylamide can be found as the sum of fragment constants shown in table 2. For example, itaconic acid can be obtained as the sum of the segment constants and correction coefficients shown in table 3.

TABLE 2

TABLE 3

* More than two cases

The smaller the value of the octanol/water partition coefficient, the more hydrophilic the value, and the more hydrophobic the value. When the octanol/water partition coefficient (LogP (Poly)) of the amphoteric polyacrylamide is more than-0.60, the amphoteric polyacrylamide adsorbs to hydrophobic inclusions (resin acids, asphalt, etc.) in the pulp slurry, and accordingly, the fixing amount on the pulp fiber becomes small and the paper strength improving effect is lowered. When the LogP (Poly) value is less than-1.44, the hydrophilicity is high, and therefore the amphoteric polyacrylamide in the aqueous solution is adsorbed and detached to the pulp fiber, and thus fixing is difficult, and the paper strength enhancing effect is lowered.

The surface tension of the amphoteric polyacrylamide to be contained in the papermaking additive of the present invention is preferably 66mN/m or more and less than 74mN/m. Here, the surface tension of the amphoteric polyacrylamide is the following value: the resulting value was measured by using a surface tensiometer (Kyowa Co., ltd.) CBVP SURFACE TENSIOMETER A3 for the surface tension of a 0.2M-ammonium acetate/0.6M-NaCl aqueous solution containing 0.2 mass% of amphoteric polyacrylamide at 25℃and adjusted to pH 7.0. When the papermaking additive does not contain an amphiphilic additive that affects the surface tension of a foaming agent or the like, the value measured by directly adjusting the concentration of the amphoteric polyacrylamide to 0.2 mass% with a buffer solution in the papermaking additive can be regarded as the surface tension specified in the present invention. On the other hand, in the case of an additive for papermaking containing an amphiphilic additive that affects the surface tension of a defoaming agent or the like, the surface tension of a buffer solution of 0.2 mass% concentration of the following amphoteric polyacrylamide was measured: amphoteric polyacrylamide is obtained by precipitating amphoteric polyacrylamide with acetone and removing the additive by vacuum drying.

The surface tension is the free energy present per unit area, and the surface tension of cellulose is 68.7mN/m (reference: japanese TAPPI journal (JAPAN TAPPI JOURNAL) Vol.39, p 733-746). The surface tension of the BKP pulp fiber was 71.3mN/m (reference: journal of fiber science Vol.49No.6 (1993)).

The amphoteric polyacrylamide contained in the papermaking additive of the present invention is preferably rapidly fixed to pulp fibers when added to a papermaking system. Therefore, when the surface tension of the amphoteric polyacrylamide is 66mN/m or more and less than 74mN/m, the amphoteric polyacrylamide is close to the surface tension of cellulose or pulp fibers, and is likely to wet and spread in the pulp fibers, and is likely to form surface adhesion, and is likely to be fixed to the pulp fibers, thereby exhibiting a paper strength enhancing effect. When the surface tension of the amphoteric polyacrylamide is less than 66mN/m, the amphoteric polyacrylamide is more likely to wet and spread in the pulp fibers, and moves into the pores of the pulp fibers, and is fixed to the pulp fibers, but cannot contribute to the paper strength improvement effect. When the surface tension is 74mN/m or more, the pulp fibers are not wet-spread and point-bonded, and therefore, it is difficult to exert the paper strength enhancing effect.

The papermaking additive of the present invention preferably has a peak top molecular weight (Mp) of 100 to 500 ten thousand, more preferably 150 to 400 ten thousand, of the amphoteric polyacrylamide contained therein. Here, the peak top molecular weight can be obtained from the position of the peak apex of the molecular weight distribution. As an index of the molecular weight, a weight average molecular weight obtained by a gel permeation chromatography (Gel Permeation Chromatography, GPC) method is generally used, but a weight average molecular weight (Mw) in which a relationship between a elution time and a molecular weight is obtained and the molecular weight is used as a weight is easily affected by the presence of a high molecular weight. Therefore, even in the case of polyacrylamide having a weight average molecular weight (Mw) in a range generally considered to exert the paper strength enhancing effect, the following may be the case: the peak top molecular weight (Mp) is low, and the paper strength enhancing effect is insufficient. When the peak top molecular weight (Mp) is 100 ten thousand or more, the paper strength enhancing effect is sufficiently obtained, and when it is 500 ten thousand or less, aggregation is less likely to occur, and the paper strength enhancing effect is excellent.

The papermaking additive of the present invention preferably has a ratio (Mw/Mn) of the weight average molecular weight (Mw) to the number average molecular weight (Mn) of the amphoteric polyacrylamide contained therein of from 2.5 to 8.0. When the ratio (Mw/Mn) of the weight average molecular weight (Mw) to the number average molecular weight (Mn) is 2.5 or more, the response to the fluctuation of the papermaking system increases due to the diversity of the amphoteric polyacrylamide, and when it is 8.0 or less, the content of the low molecular weight amphoteric polyacrylamide having a low paper strength enhancing effect or the content of the amphoteric polyacrylamide having a high molecular weight causing the excessive aggregation decreases, so that the paper strength enhancing effect is excellent.

The viscosity of the papermaking additive of the present invention is not particularly limited, and in terms of the peak top molecular weight (Mp)/viscosity (V) ratio Mp/V being easily 200 or more, the B-type viscosity (V) at 25 ℃ when diluted or concentrated so that the solid content concentration of the papermaking additive becomes 20.0 mass% is preferably 1,000mpa·s to 15,000mpa·s.

The ratio Mp/V of peak top molecular weight (Mp)/viscosity (V) is preferably 200 or more and 800 or less. If the amount is 200 or more, moderate aggregation can be generated, and if the amount is 800 or less, excessive aggregation is not easily generated, so that the paper strength enhancing effect can be improved. Here, the viscosity was measured by diluting or concentrating the solid content concentration of the papermaking additive to 20.0 mass%, adjusting the viscosity to the type B viscosity at 25 ℃ at which the pH of the papermaking additive at 20.0 mass% is 3.0 with sulfuric acid or sodium hydroxide, using the rotor of No.4 as the rotor of the type B viscometer, and adjusting the rotation speed of the rotor from 12rpm to 60rpm appropriately according to the viscosity. The unit is mPas.

The papermaking additive of the present invention is usually supplied in the form of an aqueous solution. The concentration is not particularly limited, but is preferably 10 to 40% by mass in terms of transportation cost and handling.

The present invention also provides a method for producing paper. In the method for producing paper according to the present invention, the additive for papermaking is used, and an aluminum compound is added to a pulp slurry in an amount of 0 to 0.3 mass% in terms of alumina relative to the dry mass of the pulp, and papermaking is performed at a papermaking pH of 5.0 to 8.5.

The pulp slurry is a slurry-like substance obtained by diluting pulp with water, and as pulp, any of bleached or unbleached chemical pulp such as kraft pulp and sulfite pulp, bleached or unbleached high-yield pulp such as crushed wood pulp, mechanical pulp and thermo-mechanical pulp, and old paper pulp such as old newspaper, old magazine paper, old corrugated paper and deinked old paper can be used.

In the method for producing paper according to the present invention, the papermaking additive is added to the pulp slurry in an amount of usually 0.01 to 5.0% by mass, preferably 0.05 to 3.0% by mass, and more preferably 0.5 to 3.0% by mass, based on the dry mass of the pulp. Even if an aluminum compound such as aluminum sulfate or polyaluminum chloride is not used, a paper excellent in paper strength can be obtained, but when the aluminum compound is added, it is preferable to add 0.1 to 0.3 mass% in terms of aluminum oxide.

Examples of the method of adding the papermaking additive to the pulp slurry include a method of adding the papermaking additive without using an aluminum compound at all; a method of adding an additive for papermaking after adding an aluminum compound; a method of adding an aluminum compound after adding the papermaking additive; a method of adding an aluminum compound and a papermaking additive at the same time, and the like, may be used.

In general, when NaCl or MgCl ₂ When the electrolyte of the inorganic salt is dissolved in water, the electrolyte is distributed in the aqueous solution, the interface surface is close to fresh water, negative adsorption is generated, and the surface tension of the aqueous solution is improved. The surface tension of pure water at 25℃was 72.0mN/M, but the 0.2M-NaCl aqueous solution was 72.9mN/M, the 0.6M-NaCl aqueous solution was 73.0mN/M, and the 1.2M-NaCl aqueous solution was 73.6mN/M. On the other hand, in the paper-making system, since various inorganic salts are dissolved, the amphoteric polypropyleneThe electrolyte such as amide suppresses dissociation of the ionic functional group by the shielding effect of the inorganic salt, and the hydrophobicity of the cationic group increases and the surface tension decreases. Speculation: when the deviation of the surface tension of the amphoteric polyacrylamide with respect to the surface tension of cellulose or pulp fibers becomes large, the amphoteric polyacrylamide is easily adsorbed on the hydrophobic inclusions in the pulp slurry.

Similarly, when the papermaking pH becomes neutral or higher, the surface tension is lowered because the hydrophobicity of amphoteric polyacrylamide is increased, and the hydrophobic inclusions in the pulp slurry are liable to wet and spread, resulting in a decrease in adhesion to pulp fibers and insufficient paper strength enhancing effect.

The amphoteric polyacrylamide contained in the papermaking additive of the present invention contains a quaternary cationic vinyl monomer as a cationic vinyl monomer, and the ratio of the equivalent amount of anions to the equivalent amount of cations is 0.05 or more and 1.7 or less, and therefore, it is presumed that the masking effect or the high pH is achieved without losing the cationic property, and the paper strength enhancement effect is good due to proper ion balance. On the other hand, in a strong anionic polyacrylamide having a ratio of an equivalent amount of anions to an equivalent amount of cations exceeding 1.7, an aluminum compound such as aluminum sulfate or polyaluminum chloride is required as a fixing aid for a paper strength reinforcing agent, and therefore, in a papermaking system in which only a small amount or no amount of the aluminum compound is added to a pulp slurry, a sufficient paper strength reinforcing effect cannot be obtained.

As described above, when the papermaking additive of the present invention is used, even in a papermaking system in which a sufficient paper strength enhancing effect cannot be obtained by the conventional papermaking additive, the surface tension in which the wet spread surface is easily adhered to pulp fibers is maintained, and thus an excellent paper strength enhancing effect is exhibited. The conductivity of the paper is preferably up to 5000 mS/m.

In the method for producing paper according to the present invention, an acidic rosin sizing agent (acidic rosin-based sizing agent), a neutral rosin sizing agent, an alkyl ketene dimer sizing agent, an alkenyl or alkyl succinic anhydride sizing agent, a polycarboxylic acid, and an aliphatic group having an alkyl group or alkenyl group may be added to the pulp slurryAlcohols, aliphatic amine-based condensed sizing agents (condensed sizing agents) having an alkyl group or an alkenyl group, and the like. Examples of the method of adding these sizing agents include: a method of adding a papermaking additive after adding a sizing agent to a pulp slurry; a method of adding a sizing agent after adding a papermaking additive; and a method in which the papermaking additive is diluted and mixed in advance with the sizing agent and then added. In addition to the above, the pulp slurry may suitably contain a sizing fixer, a papermaking additive other than the present invention, a defoaming agent, clay, kaolin, a filler such as calcium carbonate, barium sulfate, and titanium oxide, a pH adjuster, a dye, a fluorescent whitening agent, and the like. In addition, the basis weight of the paper obtained by the production method of the present invention is usually 10g/m ² ～750g/m ² Left and right.

Further, as needed, a surface paper strength enhancer such as a starch, a polyvinyl alcohol, an acrylamide polymer, a surface sizing agent, a dye, a coating material (coating color), an anti-slip agent, and the like may be applied by a size press, a horizontal roll coater (gate roll coater), a beer blade coater (Bill blade coater), a calender, and the like.

In the method for producing paper according to the present invention, the pH of the pulp slurry to which the papermaking additive and the like according to the present invention are added is preferably 5.0 to 8.5, more preferably 6.5 to 8.5, in terms of the paper strength enhancing effect. The pH of the paper according to the present invention is the pH of the pulp slurry immediately before dewatering by the paper machine, and the pH of the pulp slurry immediately before dewatering by the paper machine corresponds to the pH at the inlet in general practical machines.

Examples of paper produced using the papermaking additive of the present invention include: information paper such as plain paper copier (Plain Paper Copier, PPC) paper/photosensitive paper base paper/thermal paper base paper, coated base paper such as art paper (art paper), cast-coated paper (cast-coated paper), high-grade coated paper, toilet paper such as tissue paper (tissue paper), towel paper, napkin base paper, fruit tree bag base paper, laundry label base paper, decorative board base paper/wallpaper base paper, print paper, laminated board base paper, processed base paper such as food container base paper, packaging paper such as double-layer kraft paper/single-layer kraft paper for heavy object bags, electric insulating paper, cardboard paper, corrugated paper, paper tube base paper, white board base paper, gypsum board base paper, newspaper base paper, paper base paper, and the like.

Examples

The present invention will be described in more detail with reference to examples and comparative examples, but the present invention is not limited to the following examples unless the gist thereof is exceeded. Hereinafter,% represents% by mass unless otherwise specified.

The peak top molecular weight (Mp), weight average molecular weight (Mw) and number average molecular weight (Mn) of amphoteric polyacrylamide (Mw/Mn) were measured by GPC-Multi-angle light scattering (Multi-Angle Light Scattering, MALS) method in which a Multi-angle light scattering detector was connected to a gel permeation chromatograph (Gel Permeation Chromatograph, GPC). The measurement conditions are as follows.

GPC body: LC1100 series column manufactured by agilent technologies (Agilent Technology) company: sodex SB806MHQ manufactured by Showa electrician (Strand)

Eluent: n/15 phosphate buffer (pH 3) containing N/10 sodium nitrate

Flow rate: 1.0 ml/min

Detector 1: multi-angle light scattering detector DAWN manufactured by Huai Ya trickplay company (Wyatt Techology Corporation)

The detector 2: differential refractive index detector RI-101 manufactured by Showa electrician (stock)

The polymerization rate of the amphoteric polyacrylamide is achieved by ¹ H-Nuclear magnetic resonance (Nuclear Magnetic Resonance, NMR) was measured. Here, the polymerization rate means a ratio (molar ratio) of the polymer to the total amount of monomers to be reacted in the amphoteric polyacrylamide.

The LogP values of the respective copolymer components of the amphoteric polyacrylamide used in the additive for synthetic papermaking, which are obtained by the hophorid (Howard) method, are as follows.

Acrylamide: -0.8569

Sodium methallylsulfonate: 1.3949

Itaconic acid: -0.4867

Acrylic acid: 0.3920

2-acrylamide-N-glycollic acid: -2.6750

Dimethylaminoethyl methacrylate chloromethane quaternary salt: -3.3914

Dimethylaminoethyl acrylate chloromethane quaternary salt: -3.8449

Dimethylaminoethyl methacrylate benzyl chloride quaternaries: -1.6836

Dimethylaminoethyl acrylate benzyl chloride quaternaries: -2.1371

Methyl aminopropyl acrylamide methyl chloride quaternary salt: -4.4231

Diallyl dimethyl ammonium chloride: -2.5892

Dimethylaminoethyl methacrylate: 0.8290

Dimethylaminoethyl acrylate: 0.3755

N, N-dimethylacrylamide: -0.1798

N, N' -methylenebisacrylamide: -1.6145

< Synthesis of additive for papermaking >

Example 1

A1 liter four-necked flask equipped with a stirrer, a thermometer, a reflux condenser and a nitrogen inlet tube was charged with 323.60g of water, 136.13g of a 50% aqueous acrylamide solution as monomer (1), 36.35g of 80% dimethylaminoethyl methacrylate chloromethane quaternary salt, 3.06g of sodium methallylsulfonate (methallylsulfonate), 0.28g of N, N-dimethylacrylamide, 4.32g of 1% N, N' -methylenebisacrylamide, and adjusted to pH3.0 with a 30% aqueous sulfuric acid solution. Then, the temperature was raised to 65℃under a nitrogen atmosphere, ammonium persulfate was added as a polymerization initiator, polymerization was started and the reaction temperature was raised to 90 ℃. Then, 274.0g of water, 229.48g of an aqueous solution containing 50% of acrylamide, 7.29g of itaconic acid, 1.11g of sodium methallylsulfonate, 0.28g of N, N-dimethylacrylamide, and 4.32g of 1% of N, N' -methylenebisacrylamide were added to the mixture at the point when the polymerization rate reached 95%, and ammonium persulfate was further added. Then, ammonium persulfate was further added, 105.0g of water was added at a point of reaching a viscosity of 6000mpa·s at 25 ℃ to terminate the reaction, and a papermaking additive having a solid content of 20.1% was obtained. The obtained papermaking additive was adjusted to have a solid content of 20.0% and a pH of 3.0, and the results obtained by measuring the viscosity, the peak top molecular weight, the molecular weight distribution, and the surface tension, the ratio of the peak top molecular weight to the viscosity calculated from the measurement results, the ratio of the equivalent amount of anions to the equivalent amount of cations calculated from the monomer composition, and the octanol/water distribution coefficient are shown in Table 6.

Examples 2 to 4, examples 6 to 16, example 18, and example 21 comparative examples 1 to 4, comparative example 6, comparative example 7, comparative example 9, and comparative example 10

A polyacrylamide-based papermaking additive was obtained in the same manner as in example 1, except that the compositions of the monomers were changed as shown in tables 4 and 5, and the viscosities of the papermaking additives were changed as shown in table 6.

The obtained papermaking additive was adjusted to have a solid content of 20.0% and a ph of 3.0 in the same manner as in example 1, and the results obtained by measuring the viscosity, the peak top molecular weight, the molecular weight distribution, and the surface tension, the ratio of the peak top molecular weight to the viscosity calculated from the measurement results, the ratio of the equivalent amount of anions to the equivalent amount of cations calculated from the monomer composition, and the octanol/water distribution coefficient are shown in table 6.

Example 5

A1 liter four-necked flask equipped with a stirrer, a thermometer, a reflux condenser, and a nitrogen inlet tube was charged with 753.0g of water, 329.07g of a 50% aqueous acrylamide solution, 32.45g of 80% dimethylaminoethyl methacrylate chloromethane quaternary salt, 6.51g of itaconic acid, 1.38g of sodium methallylsulfonate, and 23.13g of 1% N, N' -methylenebisacrylamide, followed by adjustment to pH3.0 with a 30% aqueous sulfuric acid solution. Heating to 60 ℃ under nitrogen environment, adding ammonium persulfate as a polymerization initiator, heating to 85 ℃ under nitrogen environment, and preserving heat. After 1 hour from the start of polymerization, ammonium persulfate was additionally added, and after the start of the reaction, the polymerization was stopped after 2 hours. After cooling, a papermaking additive having a solid content of 20.1% was obtained. The obtained papermaking additive was adjusted to have a solid content of 20.0% and a ph of 3.0 in the same manner as in example 1, and the results obtained by measuring the viscosity, the peak top molecular weight, the molecular weight distribution, and the surface tension, the ratio of the peak top molecular weight to the viscosity calculated from the measurement results, the ratio of the equivalent amount of anions to the equivalent amount of cations calculated from the monomer composition, and the octanol/water distribution coefficient are shown in table 6.

Example 17

A1 liter four-necked flask equipped with a stirrer, a thermometer, a reflux condenser and a nitrogen inlet tube was charged with 262.40g of water, 147.24g of a 50% aqueous acrylamide solution as monomer (1), 7.29g of itaconic acid, 3.99g of sodium methallylsulfonate, 0.28g of N, N-dimethylacrylamide, 4.32g of 1% N, N' -methylenebisacrylamide, and adjusted to pH3.0 with a 30% aqueous NaOH solution. Then, the temperature was raised to 65℃under a nitrogen atmosphere, ammonium persulfate was added as a polymerization initiator, polymerization was started and the reaction temperature was raised to 90 ℃. Then, 333.20g of water, 218.33g of an aqueous solution containing 50% of acrylamide, 36.35g of 80% dimethylaminoethyl methacrylate methyl chloride quaternary salt, 0.18g of sodium methallyl sulfonate, 0.28g of N, N-dimethylacrylamide, and 4.32g of 1% of N, N' -methylenebisacrylamide were added to the mixture at the point when the polymerization rate reached 97%, and ammonium persulfate was further added. Then, ammonium persulfate was further added, and 111.3g of water was added at a point when the viscosity at 25℃reached 9000 mPas to complete the reaction, thereby obtaining a papermaking additive having a solid content of 20.5%. The obtained papermaking additive was adjusted to have a solid content of 20.0% and a ph of 3.0 in the same manner as in example 1, and the results obtained by measuring the viscosity, the peak top molecular weight, the molecular weight distribution, and the surface tension, the ratio of the peak top molecular weight to the viscosity calculated from the measurement results, the ratio of the equivalent amount of anions to the equivalent amount of cations calculated from the monomer composition, and the octanol/water distribution coefficient are shown in table 6.

Example 19

A papermaking additive having a solid content of 20.6% was obtained in the same manner as in example 17, except that the composition of the monomers was changed as shown in table 4 and the viscosity of the papermaking additive was changed as shown in table 6.

Example 20

A papermaking additive having a solid content of 20.8% was obtained in the same manner as in example 5, except that the composition of the monomers was changed as shown in table 4 and the viscosity of the papermaking additive was changed as shown in table 6. The obtained papermaking additive was adjusted to have a solid content of 20.0% and a ph of 3.0 in the same manner as in example 1, and the results obtained by measuring the viscosity, the peak top molecular weight, the molecular weight distribution, and the surface tension, the ratio of the peak top molecular weight to the viscosity calculated from the measurement results, the ratio of the equivalent amount of anions to the equivalent amount of cations calculated from the monomer composition, and the octanol/water distribution coefficient are shown in table 6.

Example 22

A papermaking additive was obtained in the same manner as in example 1 except that the composition of the monomers was changed as shown in table 4, the viscosity of the papermaking additive was changed as shown in table 6, and the monomer (2) was added at the point when the polymerization rate reached 99%.

Example 23

A papermaking additive having a solid content of 21.2% was obtained in the same manner as in example 1, except that the composition of the monomer was changed as shown in table 4, the viscosity of the papermaking additive was changed as shown in table 6, and monomer (2) was added and ammonium persulfate was further added.

Comparative example 5

In a 1 liter four-necked flask equipped with a stirrer, a thermometer, a reflux condenser and a nitrogen inlet tube, 70 mol% of the total amount of the monomer components contained in the composition shown in Table 5 was prepared as a part of the polymerization components, and the mixture was diluted with water so that the concentration became 30 mass%. Specifically, 219.60g of water, 255.51g of a 50% aqueous acrylamide solution as the monomer (1), 4.59g of itaconic acid, 3.10g of sodium methallylsulfonate, and 26.81g of 65% diallyldimethylammonium chloride were charged, and the pH was adjusted to 2.5 with a 30% aqueous sulfuric acid solution. Then, the temperature was raised to 60℃under a nitrogen atmosphere, and ammonium persulfate was added dropwise as a polymerization initiator and polymerized. After 5 minutes from the time when the maximum temperature of 95℃was reached due to the temperature rise accompanying the polymerization, the remaining portion (30 mol%) of the polymerization component was added dropwise. Specifically, 95.50g of water, 109.50g of 50% acrylamide aqueous solution, 1.97g of itaconic acid, 1.33g of sodium methallylsulfonate, and 11.49g of 65% diallyldimethylammonium chloride were added dropwise to the mixture. The polymerization rate at the start of the dropping of the monomer (2) was 97%.

Then, after the completion of the dropping of the remaining portion of the polymerization component, ammonium persulfate was added as a polymerization initiator twice, and the reaction was continued for 150 minutes before and after 85 ℃. Then, 363.00g of sodium sulfite as a polymerization stopper (reducing agent) and water were added and cooled, whereby a papermaking additive having a solid content of 20.5% was obtained.

The papermaking additive obtained was adjusted to have a solid content of 20.0%, a pH of 3.0 and a viscosity (25 ℃) of 581 mPas in example 1.

The results of measuring the viscosity, peak top molecular weight, molecular weight distribution, and surface tension of the obtained papermaking additive, and the ratio of peak top molecular weight to viscosity calculated from the measurement results, the ratio of the equivalent amount of anions to the equivalent amount of cations calculated from the monomer composition, and octanol/water distribution coefficient are shown in table 6.

Comparative example 8

A1 liter four-necked flask equipped with a stirrer, a thermometer, a reflux condenser and a nitrogen inlet tube was charged with 269.70g of water, 145.25g of a 50% aqueous acrylamide solution as monomer (1), 13.93g of 65% diallyldimethylammonium chloride, 2.91g of itaconic acid, 2.66g of sodium methallylsulfonate, 0.28g of N, N-dimethylacrylamide, 4.32g of 1% N, N' -methylenebisacrylamide, and adjusted to pH3.0 with a 30% aqueous sulfuric acid solution. Then, the temperature was raised to 60℃under a nitrogen atmosphere, ammonium persulfate was added as a polymerization initiator, polymerization was started and the reaction temperature was raised to 85 ℃. Then, 298.80g of water, 220.80g of a 50% aqueous acrylamide solution, 20.89g of 65% diallyldimethylammonium chloride, 4.37g of itaconic acid, 0.97g of sodium methallylsulfonate, 0.28g of N, N-dimethylacrylamide, and 4.32g of 1% N, N' -methylenebisacrylamide were added to the mixture at the point when the polymerization rate reached 90%, and ammonium persulfate was further added. Then, ammonium persulfate was further added, 100.7g of water was added at a point of time when the viscosity at 25℃reached 5000 mPas, and the reaction was completed, whereby a papermaking additive having a solid content of 20.7% was obtained. The obtained papermaking additive was adjusted to have a solid content of 20.0% and a pH of 3.0, and the results obtained by measuring the viscosity, the peak top molecular weight, the molecular weight distribution, and the surface tension, the ratio of the peak top molecular weight to the viscosity calculated from the measurement results, the ratio of the equivalent amount of anions to the equivalent amount of cations calculated from the monomer composition, and the octanol/water distribution coefficient are shown in Table 6.

TABLE 4

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The abbreviations in tables 4 and 5 are as follows.

AAm: acrylamide

SMAS: sodium methallylsulfonate

IAc: itaconic acid (itaconic acid)

AGAc: 2-acrylamide-N-glycollic acid

AAc: acrylic acid

DMAEM-MCQ: dimethyl amino ethyl methacrylate chloromethane quaternary salt (imethylaminoethylmethacrylate methyl chloride quaternary salt)

DMAEA-MCQ: dimethyl amino ethyl acrylate methyl chloride quaternary salt (dimethylaminoethylacrylate methyl chloride quaternary salt)

DMAEM-BZQ: benzyl methacrylate dimethyl amino ethyl chloride quaternary compound (dimethylaminoethylmethacrylate benzyl chloride quaternized product)

DMAEA-BZQ: benzyl chloride of dimethylaminoethyl acrylate quaternary compound (dimethylaminoethylacrylate benzyl chloride quaternized product)

DMAPA-MCQ: dimethyl amino propyl acrylamide methyl chloride quaternary salt (dimethylaminopropylacrylamide methyl chloride quaternary salt)

DADMACQ: diallyl dimethyl ammonium chloride (diallyldimethylammonium chloride)

DMAEM: dimethylaminoethyl methacrylate (dimethylaminoethyl methacrylate)

DMAEA: dimethylaminoethyl acrylate (dimethylaminoethyl acrylate)

DMAAm: n, N-dimethylacrylamide (N, N-dimethylacrylamide)

MBAAm: n, N '-methylenebisacrylamide (N, N' -methylen bisacrylamide)

TABLE 6

< evaluation of papermaking additives based on handsheet test >)

Application example 1

To an old corrugated paper pulp slurry having a density of 2.4%, a freeness (Canadian Standard Freeness) of 330 and a conductivity of 350mS/m, aluminum sulfate was added in an amount of 1.0% relative to the solid content of the pulp (0.153% in terms of aluminum oxide) and the papermaking additive obtained in example 1 was added in an amount of 0.4% relative to the solid content of the pulp. The pulp slurry was stirred, then The pulp concentration was diluted to 0.8% with water having a pH of 6.7, and then NodeB (The Noble)&Paper machine (sheet machine) manufactured by Wood), and after pressing, drying at 100deg.C for 100 seconds by a drum dryer (drum dryer) to obtain a base weight of 80g/m ² Is a paper of (3). The obtained paper was evaluated for specific rupture strength as described below. The results are shown in table 7.

Specific fracture strength: according to Japanese Industrial Standard (Japanese Industrial Standards, JIS) P8112.

Application examples 2 to 23, application comparative examples 1 to 10

In application example 1, the same operations as in application example 1 were carried out except that the types of additives for papermaking were changed as in Table 7, to obtain a basis weight of 80g/m ² Is a paper of (3). The obtained paper was evaluated in the same manner as in application example 1. The results are shown in Table 7.

TABLE 7

Application example 24

To an old corrugated paper pulp slurry having a density of 2.4%, a freeness (Canadian Standard freeness) of 330 and a conductivity of 350mS/m, 0.4% of the papermaking additive obtained in example 1 relative to the solid content of the pulp was added. The pulp slurry was stirred, and then The pulp concentration was diluted to 0.8% with water at pH7.5, and then NodeB and Wood (The Noble)&Wood) sheet machine, and after pressing, using a rollThe drum dryer was dried at 100℃for 100 seconds to give a basis weight of 80g/m ² Is a paper of (3). The obtained paper was evaluated in the same manner as in application example 1. The results are shown in table 8.

Application example 25, application comparative example 11 to application comparative example 12

The same operations as in application example 24 were carried out except that the types of additives for papermaking were changed as in Table 8 in application example 24, to obtain a basis weight of 80g/m ² Is a paper of (3). The obtained paper was evaluated in the same manner as in application example 24. The results are shown in Table 8.

TABLE 8

From tables 7 and 8, it can be seen that: the papermaking additive of the present invention is excellent in paper strength as compared with a comparative example which does not satisfy any of the regulations of the present invention.

From application example 1, application example 17 and application example 20, it is known that: the papermaking additive has a peak top molecular weight (Mp) of 100 to 500 ten thousand, and is excellent in paper strength enhancing effect as compared with a papermaking additive exceeding the above range.

As can be seen from application examples 1, 5 and 22: the papermaking additive has a peak top molecular weight (Mp)/viscosity (V) ratio Mp/V of 200 to 800, and is more excellent in paper strength enhancing effect than the papermaking additive exceeding the above range.

As can be seen from application examples 1, 21 and 23: the papermaking additive has a molecular weight distribution Mw/Mn of 2.5 to 8.0, and is excellent in the paper strength-enhancing effect as compared with the papermaking additive exceeding the above range.

Claims

1. An additive for papermaking, characterized by comprising an amphoteric polyacrylamide comprising (A) (meth) acrylamide, (B) (meth) allylsulfonic acid, (C) an anionic vinyl monomer having a carboxyl group, and (D) a cationic vinyl monomer having a quaternary ammonium as a copolymerization component,

The ratio of the equal amount of anions to the equal amount of cations of the amphoteric polyacrylamide is more than 0.05 and less than 1.7,

the octanol/water distribution coefficient of the amphoteric polyacrylamide is more than or equal to-1.44 and less than or equal to-0.60,

the surface tension of the amphoteric polyacrylamide is more than 66mN/m and less than 74mN/m,

the peak top molecular weight Mp of the amphoteric polyacrylamide is 100 ten thousand to 500 ten thousand,

the molecular weight distribution Mw/Mn is 2.5 to 8.0,

the ratio Mp/V of the peak top molecular weight Mp to the viscosity V of a 20 mass% aqueous solution (25 ℃) of the papermaking additive is 200 to 800.

2. A paper comprising the papermaking additive according to claim 1.

3. A method for producing paper, characterized in that the additive for papermaking according to claim 1 or 2 is used, an aluminum compound is added to a pulp slurry in an amount of 0 to 0.3 mass% in terms of alumina relative to the dry mass of the pulp, and the paper is made at a papermaking pH of 5.0 to 8.5.

4. The method of producing paper according to claim 3, wherein the paper conductivity exceeds 300mS/m.