JP5682849B2 - Wet paper strength improver and wet paper strength improver internal paper - Google Patents

Description

  The present invention relates to a wet paper strength improver and a paper containing a wet paper strength improver.

  As the wet paper strength improver, polyamide polyamine-epihalohydrin resin (PAE) and polyamide polyamine polyurea-epihalohydrin resin (PAUE) are generally used as useful wet strength agents, and their production methods are publicly known. (For example, see Patent Document 1 and Patent Document 2).

  In recent years, in order to reduce the content of low-molecular-weight organic halogen compounds that are suspected to be carcinogenic, basic substances and nucleophilic substances are reacted during production to produce PAEs and PAUEs that are low in low-molecular-weight organic halogen compounds. The method of doing is well-known (for example, refer patent document 3, refer patent document 4, refer patent document 5). Also, a method for producing PAE or PAUE with a small amount of low-molecular organic halogen compounds by reacting a nucleophilic substance containing a sulfur atom and a nucleophilic substance containing a nitrogen atom is known (see, for example, Patent Document 6).

Japanese Patent Publication No.35-003547 Japanese Patent Publication No.43-028476 JP-A-06-001842 JP 06-220189 A JP 2004-075818 JP 2007-297511 A

  An object of the present invention is to provide a wet paper strength improver having a high solid content and excellent storage stability and having an excellent wet paper strength improving effect, and a paper containing the wet paper strength improver.

  As a result of intensive studies to solve the above problems, the present inventors have found that PAE and PAUE that apply to a specific composition and various parameters exhibit an excellent wet paper strength improvement effect as a wet paper strength improver, In addition, by combining the above-mentioned wet paper strength improver and a specific dry paper strength improver, it is possible to combine both the wet paper strength improver and the specific softening agent. The present inventors have found that a paper excellent in both wet paper strength and flexibility can be obtained, and the present invention has been completed.

That is, the present invention is a resin obtained by reacting <1> (A) a polyalkylene polyamine and a dibasic carboxylic acid with a polyamide polyamine obtained by reacting with an epihalohydrin. Polyamide polyamine / epihalohydrin resin obtained by reacting at a ratio of mol%, dibasic carboxylic acid 28 to 33 mol%, and epihalohydrin 34 to 40 mol%, or
(B) a resin obtained by reacting a polyalkylene polyamine, a dibasic carboxylic acid and a urea, and a polyamidopolyamine polyurea and an epihalohydrin, wherein the polyalkylene polyamine is 30 to 35 mol%, Containing a polyamide polyamine polyurea / epihalohydrin resin obtained by reaction at a ratio of 29 to 34 mol% of dibasic carboxylic acids, 3.9 to 15 mol% of ureas, and 24 to 36 mol% of epihalohydrins,
(1) Intrinsic viscosity is 0.13 to 0.40 dL / g,
(2) The Huggins constant is 0.50 to 1.00,
(3) The cationization degree at pH 10 is 1.2 to 2.6 meq / g per solid content,
(4) The weight average molecular weight is 500,000-3 million,
(5) A wet paper strength improver characterized in that the ratio of components having a weight average molecular weight of 50,000 or more is 50% by mass or more,
<2> The aqueous solid content of the wet paper strength improver is 20 to 31% by mass,
The wet paper strength improver has a pH of 2.6 to 4.0,
The wet paper strength improver according to the above <1>, comprising 0.05 to 2.00% by mass of a water-soluble carboxylic acid,
<3> The wet paper strength improver according to <1> or <2> is 0.01 to 2.00% by mass of solid content, and the dry paper strength improver of (P1) or (P2) below. Paper containing 0.05 to 3% solids by mass.
(P1) An acrylamide copolymer-based dry paper strength improver (M1) (meth) acrylamide obtained by polymerizing the following monomers (M1) to (M3) and the monomer (M4) as necessary: 80 to 95 mol %,
(M2) (meth) allylsulfonic acid and its salts are 0.05 to 4.00 mol%,
(M3) 0.1 to 18.0 mol% of a vinyl monomer having a carboxyl group and salts thereof
(M4) 0.1-18.0 mol% of vinyl monomer having tertiary amino group and / or vinyl monomer having quaternary ammonium salt
(P2) Water-soluble cellulose derivative <4> The wet paper strength improver described in <1> or <2> is 0.01 to 2.00% by mass of solid content, and the following (S1) to (S3) Paper containing 0.05 to 3.00 solids mass% of at least one softener,
(S1) Fatty acid amide epihalohydrin resin (S2) Quaternary ammonium salt having an alkyl group and / or alkenyl group represented by the following general formula (1) (1)

(In the formula, R ¹ is an alkyl group having 6 to 22 carbon atoms or an alkenyl group having 6 to 22 carbon atoms, and R ² and R ³ are (EO) _m (PO) _n H, carbon numbers 1 to 22). R ² and R ³ may be the same as or different from each other, X ⁻ is an anion, and E is An ethylene group, wherein P represents a propylene group, and the total of m and n is 1 to 60. The addition form of ethylene oxide and / or propylene oxide may be random or block, where m and n are Average number of moles added.)
(S3) Component general formula (2) represented by the following general formula (2) R ⁴ —A ¹ — (EO) _m (PO) _n —R ⁵
(In the formula, —A ¹ — represents —O— or —COO—, R ⁴ represents an alkyl group having 6 to 24 carbon atoms or an alkenyl group having 6 to 24 carbon atoms, and R ⁵ represents 6 carbon atoms. Represents an alkyl group having 24 to 24 carbon atoms, an alkenyl group having 6 to 24 carbon atoms, an alkyl group having 6 to 24 carbon atoms or an alkenyl group having 6 to 24 carbon atoms, or a hydrogen group, and R ⁴ and R ⁵ are They may be the same or different, E represents an ethylene group, P represents a propylene group, and the sum of m and n is 1 to 60, where m and n are the average number of moles added. )
<5> The paper according to <3> or <4>, wherein the paper is sanitary paper or hybrid paper,
It is.

  The wet paper strength improver of the present invention has an excellent wet paper strength enhancing effect, and has excellent properties such as excellent storage stability despite its high solid content.

  The paper of the present invention exhibits excellent wet paper strength and is therefore suitable as a wet paper strength paper. Particularly, the properties excellent in dry paper strength and flexibility are optimal as sanitary paper and packaging paper.

The present invention relates to (A) a resin obtained by reacting a polyalkylenepolyamine and a dibasic carboxylic acid with a polyamide polyamine obtained by reacting with an epihalohydrin. Polyamide polyamine / epihalohydrin resin obtained by reaction at a ratio of 28 to 33 mol% of basic carboxylic acids and 34 to 40 mol% of epihalohydrins, or
(B) A resin obtained by reacting a polyalkylene polyamine, a dibasic carboxylic acid and a urea, and a polyamidopolyamine polyurea and an epihalohydrin, wherein the polyalkylene polyamine is 30 to 35 mol%, Containing a polyamide polyamine polyurea / epihalohydrin resin obtained by reaction at a ratio of 29 to 34 mol% of dibasic carboxylic acids, 3.9 to 15 mol% of ureas, and 24 to 36 mol% of epihalohydrins,
(1) Intrinsic viscosity is 0.13-0.4 dL / g,
(2) The Huggins constant is 0.5-1
(3) The cationization degree at pH 10 is 1.2 to 2.6 meq / g per solid content,
(4) The weight average molecular weight is 500,000-3 million,
(5) A wet paper strength improver characterized in that the proportion of a component having a weight average molecular weight of 50,000 or more is 50% by mass or more.

The polyalkylene polyamines used in the present invention may be those having at least two alkylene groups and two or more amino groups in the molecule, such as diethylenetriamine, triethylenetetramine, tetraethylenepentamine. , Pentaethylenehexamine, hexaethyleneheptamine, dipropylenetriamine, tripropylenetetramine, iminobispropylamine, and the like. These may be used alone or in combination of two or more. Among these, diethylenetriamine, triethylenetetramine, and tetraethylenepentamine are preferable because they are excellent in wet paper strength improvement effect. Furthermore, diethylenetriamine is particularly preferable. These may be used alone or in combination of two or more. In addition to polyalkylenepolyamines, alkylenediamines such as ethylenediamine, propylenediamine or hexamethylenediamine, aminocarboxylic acids having 1 to 6 carbon atoms such as ε-aminocaproic acid, and amino acids having 1 to 6 carbon atoms such as ε-caprolactam. Carboxylic acid lactams can also be used.

The dibasic carboxylic acid used in the present invention may have two dibasic carboxylic acids and / or derivatives thereof in the molecule. Examples of the derivative include mono- or diesters of these dibasic carboxylic acids, or acid anhydrides. Examples of the dibasic carboxylic acid include malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, brassic acid, dodecanedioic acid and the like. A dibasic carboxylic acid having a number of 5 to 10 is preferred. Moreover, as mono- or diester of dibasic carboxylic acid, Preferably it is C1-C5, Most preferably, C1-C3 lower alcohol (methyl, ethyl, propyl) ester can be mentioned. Examples of the acid anhydride include an intramolecular dehydration condensate of a free acid and a condensate of a lower carboxylic acid, preferably a lower carboxylic acid having 1 to 5 carbon atoms. Particularly preferred industrially preferred dibasic carboxylic acids include adipic acid, glutaric acid dimethyl ester, and adipic acid dimethyl ester. The above dibasic carboxylic acids can be used alone or in combination of two or more. Moreover, as a part of dibasic carboxylic acids, it is also possible to use derivatives having 3 or more carboxylic acids and / or carboxylic acid esters or acid anhydrides thereof in the molecule, such as citric acid and trimellitic acid. it can.

Examples of ureas used in the present invention include urea, thiourea, guanylurea, phenylurea, methylurea, dimethylurea and the like. Of these, urea is particularly preferred industrially. As a part of these ureas, instead of ureas, compounds having one or more N unsubstituted amide groups capable of undergoing an amide exchange reaction with amino groups, for example, aliphatic amides such as acetamido and propionamide, benzamide, phenyl Aromatic amides such as acetic acid amide can also be used.

  The epihalohydrins used in the present invention include epichlorohydrin, epibromohydrin and the like, and epichlorohydrin is preferred industrially.

  The (A) polyamide polyamine / epihalohydrin resin (PAE) in the present invention is a resin obtained by reacting a polyalkylene polyamine and a dibasic carboxylic acid with an epihalohydrin.

The (A) PAE resin of the present invention comprises 28 to 33 mol% of polyalkylene polyamines, particularly 30 to 32%, 28 to 33 mol% of dibasic carboxylic acids, particularly 30 to 31 mol%, and 34 to 40 mol of epihalohydrins. %, Particularly 37 to 40 mol%, a wet paper strength improver excellent in wet paper strength improvement effect can be obtained.

  In the present invention, (B) polyamide polyamine polyurea / epihalohydrin resin (PAUE) is obtained by reacting polyalkylene polyamines, dibasic carboxylic acids, and ureas with a polyamido polyamine polyurea and epihalohydrin. The resulting resin. The reaction of polyalkylene polyamines, dibasic carboxylic acids and ureas can be performed in any order or simultaneously. For example, polyalkylene polyamines, dibasic carboxylic acids, and ureas can be reacted simultaneously. Alternatively, a polyalkylene polyamine can be reacted with urea to obtain a polyalkylene polyamine polyurea, and then the polyalkylene polyamine polyurea can be reacted with a dibasic carboxylic acid. Furthermore, a polyalkylene polyamine and a dibasic carboxylic acid can be reacted to obtain a polyamide polyamine, and the polyamide polyamine and urea can be reacted.

  (B) PAUE resin of the present invention comprises polyalkylene polyamines 30 to 35 mol%, particularly 30 to 32%, dibasic carboxylic acids 29 to 34 mol%, particularly 29 to 31 mol%, ureas 3.9 to A wet paper strength improver excellent in wet paper strength improvement effect can be obtained by reacting at 15 mol%, particularly 4 to 10 mol%, epihalohydrins 24 to 36 mol%, particularly 28 to 34 mol%.

  In the condensation reaction of polyalkylene polyamines and dibasic carboxylic acids, or polyalkylene polyamines and urea, or polyamide polyamines and ureas, dehydration and / or dealcoholization and / or deammonification reaction is performed by heating. From the viewpoint of reaction control, the reaction temperature is preferably 110 to 250 ° C. and the reaction time is 1 to 8 hours. At this time, as a catalyst for the polycondensation reaction, sulfonic acids such as sulfuric acid, benzenesulfonic acid, and paratoluenesulfonic acid, phosphoric acids such as phosphoric acid, phosphonic acid, and hypophosphorous acid, and other known catalysts may be used alone or in combination. These can be used in combination.

  When the polyamide polyamine and / or the polyamide polyamine polyurea and the epihalohydrin are reacted, the reaction solution concentration is preferably 10 to 80% by mass, and the reaction temperature is preferably 5 to 90 ° C. although it depends on the reaction concentration.

  In the reaction of polyamide polyamine and / or polyamide polyamine polyurea with epihalohydrin, an alkali substance or a nucleophilic substance containing a sulfur atom can be added for the purpose of reducing a low molecular organic halogen compound. The alkali substance or nucleophilic substance may be added to the polyamide polyamine in advance before the reaction with the epihalohydrin, or may be added during or after the reaction. Preferably, it is added during the reaction.

  Examples of the alkaline substance include sodium hydroxide and potassium hydroxide as inorganic alkaline substances, and examples of the alkaline substance containing a nitrogen atom include monoalkylamines such as methylamine, ethylamine and monoethanolamine, dimethylamine, diethylamine and diethanolamine. Examples include dialkylamines such as trialkylamines such as trimethylamine, triethylamine, and triethanolamine, ammonia, and polyalkylene polyamines such as ethylenediamine, diethylenetriamine, tetraethylenepentamine, and iminobispropylamine, and polyvinylamine. One or more kinds can be used from the inside. Among these, sodium hydroxide and ammonia are preferable because they are excellent in reducing low molecular organic halogen compounds.

  The nucleophilic substance containing the sulfur atom may be any compound having a sulfur atom in the molecule and having nucleophilicity, such as sodium sulfite, potassium sulfite, sodium hydrogen sulfite, sodium metabisulfite, Inorganic compounds such as acidic potassium sulfite, sodium thiosulfate, potassium thiosulfate, sodium sulfide, potassium sulfide, sodium hydrosulfide, potassium hydrosulfide, ammonium thiocyanate, potassium thiocyanate, sodium thiocyanate, and 2-mercaptobenzothiazole or Its sodium salt, 2-mercaptobenzimidazole or its sodium salt, 2-mercaptothiazole or its sodium salt, 2-mercaptoimidazole or its sodium salt, alkylthiol or its sodium salt, benzenethiol or its sodium Unsalted, organic compounds such as thiourea or an alkali metal salt, and the like, can be used one or more from these. Among these, sulfites, hydrogen sulfites, and metabisulfites are preferable. Specifically, sodium hydrogensulfite and sodium metabisulfites are preferable because they are excellent in reducing low-molecular organic halogen compounds.

  In the course of the reaction between polyamide polyamine and epihalohydrin, inorganic acids such as sulfuric acid, nitric acid, and phosphoric acid, organic acids such as formic acid, and acetic acid, preferably halogens are not included for the purpose of easily controlling the increase in viscosity. One or more acids such as inorganic acids and organic acids can be added.

  Water was added to the reaction product to stop the reaction, and after cooling, an inorganic acid such as hydrochloric acid, sulfuric acid, nitric acid, and phosphoric acid, and a water-soluble carboxylic acid such as formic acid and acetic acid were added to adjust the pH to 2.6 to It is preferable to adjust to 4, more preferably 0.05 to 2% by mass of water-soluble carboxylic acid from the viewpoint of improving storage stability. Finally, it is preferable to adjust the solid content to 20 to 31% by adding water as necessary in order to achieve both high concentration and improvement in storage stability.

(A) PAE resin or (B) PAUE resin contained in the wet paper strength improver thus obtained,
(1) Intrinsic viscosity is 0.13-0.4 dL / g,
(2) The Huggins constant is 0.5-1
(3) The cationization degree at pH 10 is 1.2 to 2.6 meq / g per solid content,
(4) The weight average molecular weight is 500,000-3 million,
(5) The proportion of components having a weight average molecular weight of 50,000 or more needs to be 50% by mass or more.
Here, the intrinsic viscosity is a physical quantity that depends on the molecular weight, shape, and size of the polymer chain that is independently dissolved in the solvent. If the structure such as the degree of branching of the polymer is the same, the intrinsic viscosity increases as the molecular weight increases. On the other hand, the Haggins constant is a value indicating the intermolecular interaction of the polymer in a dilute solution state.

  The intrinsic viscosity of the (A) PAE resin or (B) PAUE resin contained in the wet paper strength improver of the present invention needs to be 0.13 to 0.40 dL / g. When the intrinsic viscosity is less than 0.13, the wet paper strength improving effect is insufficient, and when it exceeds 0.40, the storage stability is remarkably deteriorated. In particular, the intrinsic viscosity of the (A) PAE resin or (B) PAUE resin contained in the wet paper strength improver is preferably 0.20 to 0.40 dL / g.

  The hugging constant of (A) PAE resin or (B) PAUE resin contained in the wet paper strength improver of the present invention needs to be 0.50 to 1.00. When the Huggins constant is less than 0.50, the storage stability is remarkably deteriorated, and when it exceeds 1.00, the wet paper strength improvement effect is insufficient. In particular, the hugging constant of (A) PAE resin or (B) PAUE resin contained in the wet paper strength improver is preferably 0.60 to 0.90.

  The cationization degree at pH 10 of the (A) PAE resin or (B) PAUE resin contained in the wet paper strength improver of the present invention needs to be 1.2 to 2.6 meq / g per solid content. When the cationization degree at pH 10 is less than 1.2 meq / g per solid content, the wet paper strength improving effect is insufficient, and when it exceeds 2.6 meq / g, excessive aggregation of the pulp fibers occurs, resulting in wet paper strength. Improvement effect becomes insufficient.

  The weight average molecular weight of the (A) PAE resin or (B) PAUE resin contained in the wet paper strength improver of the present invention needs to be from 500 to 3,000,000. When the weight average molecular weight is less than 500,000, the wet paper strength improving effect is insufficient, and when it exceeds 3 million, the storage stability is remarkably deteriorated.

  The ratio of the component having a weight average molecular weight of 50,000 or more of the (A) PAE resin or (B) PAUE resin contained in the wet paper strength improver of the present invention needs to be 50% by mass or more. When the ratio of the component having a weight average molecular weight of 50,000 or more is less than 50% by mass, the effect of improving the wet paper strength becomes insufficient.

  The wet paper strength improver of the present invention can be used for the purpose of improving wet paper strength. The method of using the wet paper strength improver is a method of adding the wet paper strength improver to the pulp slurry, surface coating or impregnation treatment with the wet paper strength improver using a size press, gate roll coater, etc. Among them, a method of adding a wet paper strength improver to the pulp slurry (internal addition) is preferable.

  When used internally as a wet paper strength improver, it is usually 0.01 to 2.00 solids mass%, preferably 0 per dry mass of pulp in the aqueous dispersion of the pulp or in the white water of the fan pump part. 0.05 to 1.20% by mass of solid content can be added and used. It is preferable that the wet paper strength improver at the time of addition is appropriately used after being diluted 1 to 200 times.

  Paper containing the wet paper strength improver of the present invention is bleached or unbleached high-yield pulp such as bleached or unbleached chemical pulp, crushed wood pulp, mechanical pulp or thermomechanical pulp such as kraft pulp or sulfite pulp. Waste paper pulp such as waste newspaper, magazine waste, corrugated waste paper or deinked waste paper can be contained. Moreover, you may contain the mixture of synthetic fibers, such as the said pulp raw material, polyamide, a polyimide, polyester, polyolefin, and polyvinyl alcohol.

  In producing the paper of the present invention, additives such as fillers, sizing agents, dry paper strength improvers, softeners, yield improvers, paper thickness improvers, opacifiers and drainage improvers are also included in each paper type. In order to express the physical properties required for the above, it may be used as necessary. These may be used alone or in combination of two or more. These can be mixed with the wet paper strength improver of the present invention and added to the stock, and the mixing method is not particularly limited.

  Examples of the filler include clay, talc, and calcium carbonate. These may be used alone or in combination of two or more.

  Examples of the yield improver include anionic, cationic or amphoteric high molecular weight polyacrylamide, combined use of silica sol and cationized starch, and combined use of bentonite and cationic high molecular weight polyacrylamide. These may be used alone or in combination of two or more.

Examples of the drainage improver include polyethyleneimine or cationic, amphoteric or anionic polyacrylamide. These may be used alone or in combination of two or more.

  Sizing agents include fatty acid soap sizing agents such as sodium stearate, rosin, reinforced rosin, and rosin ester sizing agents, aqueous emulsions of alkenyl succinic anhydride, aqueous emulsions of 2-oxetanone, aqueous emulsions of paraffin wax, Examples thereof include a cationic sizing agent obtained by the reaction of a carboxylic acid and a polyvalent amine, an aqueous emulsion of a reaction product of an aliphatic oxyacid and an aliphatic amine or an aliphatic alcohol, and a cationic styrene sizing agent. These may be used alone or in combination of two or more.

  Examples of the dry paper strength improver include anionic polyacrylamide, cationic polyacrylamide, amphoteric polyacrylamide, cationized starch, amphoteric starch, and water-soluble cellulose derivative. These may be used alone or in combination of two kinds. You may use the above together.

  Examples of the softening agent include dilong chain alkyl quaternary ammonium salts, fatty acid amide resins, fatty acid amide amine resins, fatty acid amide epihalohydrin resins, polyalkylene alkyl ethers, polyalkylene alkyl esters, and the like.

  Also, with size press, gate roll coater, bill blade coater, calendar, etc., surface paper strength improver such as starch, polyvinyl alcohol and acrylamide polymer, dye, coating color, surface sizing agent, anti-slip agent, polyhydric alcohol type A moisturizing agent or the like may be applied as necessary. These may be used alone or in combination of two or more.

  Paper and paperboard produced using the wet paper strength improver obtained by the production method of the present invention include information paper such as PPC paper, photosensitive paper base, and thermal paper base, tissue paper, towel paper, and napkin base paper. Hygiene paper, decorative board paper, wallpaper base paper, photographic paper base paper, laminated base paper, food container base paper, oil-resistant paper, cigarette chips, tea bag base paper, hybrid paper such as speaker corn base paper, double bag for heavy bags These include kraft paper, single-sided kraft paper, wrapping paper, electrical insulation paper, water resistant liner, water resistant core, newsprint paper, paperboard paperboard, etc. Gives a power-enhancing effect. In particular, the wet paper strength improving agent of the present invention is excellent in the wet paper strength improving effect, and is preferably used for sanitary paper and hybrid paper.

  A paper containing a wet paper strength improver and a dry paper strength improver provides a paper that is excellent in both wet paper strength and dry paper strength. Therefore, when producing paperboard, sanitary paper, packaging paper, and hybrid paper, preferable.

In particular, as a paper containing the wet paper strength improver and the dry paper strength improver of the present invention, the wet paper strength improver is 0.01 to 2.00 solids by mass%, and the following (P1) or (P2) It is preferable to contain 0.05 to 3.00% by mass of a dry paper strength improver.
(P1) An acrylamide copolymer-based dry paper strength improver (M1) (meth) acrylamide obtained by polymerizing the following monomers (M1) to (M3) and the monomer (M4) as necessary: 80 to 95 mol %,
(M2) (meth) allylsulfonic acid and its salts are 0.05 to 4.00 mol%,
(M3) 0.1 to 18.0 mol% of a vinyl monomer having a carboxyl group and salts thereof
(M4) 0.1-18.0 mol% of vinyl monomer having tertiary amino group and / or vinyl monomer having quaternary ammonium salt
(P2) Water-soluble cellulose derivative

  As the dry paper strength improver used in the present invention, (P1) an acrylamide copolymer dry strength improver obtained by polymerizing the monomers (M1) to (M3) and (M4) as necessary. Can be mentioned. The dry paper strength improver obtained by polymerizing the monomers (M1) to (M4) is preferable because both the wet paper strength improvement effect and the dry paper strength improvement effect are excellent.

  Examples of the (meth) acrylamide that is the monomer of (M1) include acrylamide and methacrylamide.

  The (M2) monomer (meth) allylsulfonic acid and salts thereof are methallylsulfonic acid or allylsulfonic acid and alkali metal salts, alkaline earth metal salts, and ammonium salts thereof.

  Examples of the vinyl monomer having a carboxyl group as the (M3) monomer include unsaturated monocarboxylic acids such as acrylic acid, methacrylic acid, and crotonic acid, fumaric acid, maleic acid, itaconic acid, citraconic acid, and muconic acid. And unsaturated dicarboxylic acids such as unsaturated dicarboxylic acid such as aconitic acid, 3-butene-1,2,3-tricarboxylic acid and 4-pentene-1,2,4-tricarboxylic acid. Examples of the salt of a vinyl monomer having a carboxyl group include alkali metal salts, alkaline earth metal salts, and ammonium salts of vinyl monomers having a carboxyl group. These may be used individually by 1 type and may use 2 or more types together.

  Examples of the vinyl monomer having a tertiary amino group as the (M4) monomer include dimethylaminoethyl (meth) acrylate, diethylaminoethyl (meth) acrylate, dimethylaminopropyl (meth) acrylate, and diethylaminopropyl (meth) acrylate. Dialkylaminoalkyl (meth) acrylates, dimethylaminopropyl (meth) acrylamide, and dialkylaminoalkyl (meth) acrylamides such as diethylaminopropyl (meth) acrylamide, hydrochlorides of vinyl monomers having the tertiary amino group, and Examples thereof include inorganic acid salts such as sulfates, and organic acid salts such as formates of vinyl monomers having a tertiary amino group and acetates. Moreover, as a vinyl monomer which has the quaternary ammonium salt which is the said (M4) monomer, the vinyl monomer obtained by reaction of the vinyl monomer which has the said tertiary amino group, and a quaternizing agent is mentioned. Examples of the quaternizing agent include alkyl halides such as methyl chloride and methyl bromide, aralkyl halides such as benzyl chloride and benzyl bromide, dimethyl sulfate, diethyl sulfate, epichlorohydrin, 3-chloro-2-hydroxypropyltrimethyl. Ammonium chloride, glycidyl trialkyl ammonium chloride, etc. are mentioned. These vinyl monomers having a tertiary amino group or a quaternary ammonium salt may be used alone or in combination of two or more.

  In addition to using the monomers (M1) to (M3) and the monomer (M4) as necessary, a polyfunctional crosslinking monomer or nonionic vinyl monomer may be used in combination.

  Examples of the polyfunctional crosslinkable monomer include bifunctional monomers such as di (meth) acrylates, bis (meth) acrylamides, divinyl esters, and the like, trifunctional monomers, and tetrafunctional monomers. Etc. The polyfunctional crosslinking monomer can be used at 0.5 mol% or less.

  Examples of nonionic vinyl monomers include N-substituted (meth) acrylamide, (meth) acrylic acid ester, (meth) acrylonitrile, styrene, styrene derivatives, vinyl acetate, vinyl propionate, and methyl vinyl ether. These may be used alone or in combination of two or more. A nonionic vinyl monomer can be used at 10 mol% or less.

  The acrylamide copolymer-based dry paper strength improver in the present invention is synthesized by batch polymerization, divided addition polymerization, or dropwise polymerization.

  As the polymerization initiator used in the present invention, conventionally known polymerization initiators can be used. Specifically, persulfates such as sodium persulfate, potassium persulfate and ammonium persulfate, peroxides such as benzoyl peroxide, hydrogen peroxide, tert-butyl hydroperoxide, di-tert-butyl peroxide, bromine Bromate such as sodium acid, potassium bromate, perborate such as sodium perborate, ammonium perborate, percarbonate such as sodium percarbonate, potassium percarbonate, ammonium percarbonate, sodium perphosphate, Perphosphates such as potassium perphosphate and ammonium perphosphate can be used. In this case, one kind can be used alone, but two or more kinds may be used in combination, and use as a redox polymerization agent in combination with a reducing agent may be mentioned. Examples of the reducing agent include sulfites such as sodium sulfite, bisulfites such as sodium bisulfite, organic amines such as N, N, N ′, N′-tetramethylethylenediamine, and reducing sugars such as aldose. it can. Moreover, these reducing agents may be used individually by 1 type, and may be used together 2 or more types. Other than the above, azobisisobutyronitrile, 2,2′-azobis (2-amidinopropane) hydrochloride, 2,2′-azobis (2-methylpropionamidine) hydrochloride, 2,2′-azobis An azo polymerization initiator such as (2,4′-dimethylvaleronitrile), 4,4′-azobis (4-cyanovaleric acid) and a salt thereof can also be used. Usually, a polymerization initiator is added to the monomer solution to initiate the polymerization. However, for the purpose of reducing the residual monomer, a part of the polymerization initiator may be additionally added during the polymerization.

  Moreover, a conventionally well-known chain transfer agent can be used suitably with a polymerization initiator as needed. Conventionally known chain transfer agents include compounds having one or more hydroxyl groups in the molecule, such as oligomers and polymers such as ethanol, isopropyl alcohol, butanol, ethylene glycol, glycerin alcohols, polyethylene oxide, polyglycerin, Examples thereof include sugars such as glucose, ascorbic acid, and sucrose, and vitamins. And compounds containing one or more mercapto groups in the molecule, such as butyl mercaptan, mercaptoethanol, thioglycolic acid and its ester, mercaptopropionic acid and its ester, thioglycerin, cysteamine and its salt, etc. Can do. In addition, compounds having one or more carbon-carbon unsaturated bonds in the molecule, such as (meth) allyl alcohol and its ester derivatives, (meth) allylamine, diallylamine, dimethallylamine and its amide derivatives, triallylamine, trimetallic Luamine, allyl sulfides, allyl mercaptans and the like can be mentioned. Furthermore, peroxides, such as dibutyl peroxide, and hypophosphorous acid can be mentioned.

  Examples of the dry paper strength improver used in the present invention include (P2) water-soluble cellulose derivatives. The water-soluble cellulose derivative is a water-soluble compound derived from cellulose, which reacts with various etherifying agents to carboxymethylate, sulfoethylate, urea phosphate ester, sulfosuccinate ester of the hydroxyl group of cellulose. And chemically modified cellulose derivatives such as 2-hydroxy-3- (trimethylammonio) propylation, methylation, hydroxymethylation, hydroxypropylation, and the like. Among these, carboxymethylcellulose, its metal salt, and ammonium salt are preferable.

Products having various degrees of etherification and viscosity are commercially available for carboxymethylcellulose, but can be suitably used in the present invention as long as they have sufficient water solubility.
When the degree of etherification is 2.0 or less, more preferably in the range of 0.2 to 1.5, and the viscosity of the 1% solid content aqueous solution at 25 ° C. is 2000 mPa · s or less, further 1 to 1000 mPa · s. Due to the synergistic effect with PAE and PAUE which are wet paper strength improvers, it is easy to obtain a paper excellent in both wet paper strength and dry paper strength, which is preferable.

A paper containing both a wet paper strength improver and a softening agent is preferable in producing sanitary paper because a paper excellent in both wet paper strength and softness can be obtained.

In particular, as the paper containing the wet paper strength improver and the softener of the present invention, the wet paper strength improver is 0.01 to 2% by mass in solid content, and at least one of the following (S1) to (S3) softness. It is preferable to contain 0.05-3 solid mass% of an agent.
(S1) Fatty acid amide epihalohydrin resin (S2) Quaternary ammonium salt having an alkyl group and / or alkenyl group represented by the following general formula (1) (1)

（但し、式中、Ｒ^１は炭素数６〜２２のアルキル基又は炭素数６〜２２のアルケニル基を、Ｒ^２とＲ^３とは（ＥＯ）_ｍ（ＰＯ）_ｎＨ、炭素数１〜２２のアルキル基、及び炭素数１〜２２のアルケニル基から選ばれる１種を示し、かつＲ^２とＲ^３とは同一又は相異していてもよく、Ｘ−は陰イオンであり、前記Ｅはエチレン基を示し、前記Ｐはプロピレン基を示し、ｍとｎとの合計は１〜６０である。エチレンオキサイド、及び／又はプロピレンオキサイドの付加形態はランダムでもブロックでも良い。なお、ｍ及びｎは平均付加モル数である。）
（Ｓ３）下記一般式（２）で表される成分
一般式（２） Ｒ^４−Ａ¹−(ＥＯ)_ｍ(ＰＯ)_ｎ−Ｒ^５
（但し、式中、−Ａ¹−は−Ｏ−又は−ＣＯＯ−を示し、Ｒ^４は炭素数６〜２４のアルキル基又は炭素数６〜２４のアルケニル基を示し、Ｒ^５は炭素数６〜２４のアルキル基又は炭素数６〜２４のアルケニル基、炭素数６〜２４のアルキル基又は炭素数６〜２４のアルケニル基を有するアシル基、又は水素基を示し、Ｒ^４とＲ^５とは同一又は相異していてもよく、Ｅはエチレン基を示し、Ｐはプロピレン基を示し、ｍとｎとの合計は１〜６０である。なお、ｍ及びｎは平均付加モル数である。）

(In the formula, R ¹ is an alkyl group having 6 to 22 carbon atoms or an alkenyl group having 6 to 22 carbon atoms, and R ² and R ³ are (EO) _m (PO) _n H, carbon numbers 1 to 22). R ² and R ³ may be the same or different, X- is an anion, and E is an anion. An ethylene group, wherein P represents a propylene group, and the total of m and n is 1 to 60. The addition form of ethylene oxide and / or propylene oxide may be random or block, where m and n are Average number of moles added.)
(S3) Component general formula (2) represented by the following general formula (2) R ⁴ —A ¹ — (EO) _m (PO) _n —R ⁵
(In the formula, —A ¹ — represents —O— or —COO—, R ⁴ represents an alkyl group having 6 to 24 carbon atoms or an alkenyl group having 6 to 24 carbon atoms, and R ⁵ represents 6 carbon atoms. Represents an alkyl group having 24 to 24 carbon atoms, an alkenyl group having 6 to 24 carbon atoms, an alkyl group having 6 to 24 carbon atoms or an alkenyl group having 6 to 24 carbon atoms, or a hydrogen group, and R ⁴ and R ⁵ are They may be the same or different, E represents an ethylene group, P represents a propylene group, and the sum of m and n is 1 to 60, where m and n are the average number of moles added. )

  Examples of the softener used in the present invention include (S1) fatty acid amide epihalohydrin resin. The fatty acid amide epihalohydrin resin is a compound obtained by reacting an epihalohydrin with an amide compound obtained by reacting a polyalkylene polyamine, a monocarboxylic acid having 6 to 24 carbon atoms, and if necessary urea.

  Examples of the polyalkylene polyamines, ureas, and epihalohydrins used in the softener (S1) fatty acid amide epihalohydrin resin of the present invention include the polyalkylene polyamines, ureas, epihalohydrins used in the wet paper strength agent of the present invention. Any of those listed in the class may be used.

  The monocarboxylic acids having 6 to 24 carbon atoms used in the softening agent (S1) fatty acid amide epihalohydrin resin of the present invention may be any one that can form an amide compound by reacting with a polyalkylene polyamine. Specific examples of monocarboxylic acids having 6 to 24 carbon atoms include lauric acid, palmitic acid, stearic acid, myristic acid, myristoleic acid, palmitoleic acid, oleic acid, elaidic acid, erucic acid, nervonic acid, linoleic acid, and linolenic acid Eicosapentaenoic acid, docosahexaenoic acid, esters of these fatty acids, acid anhydrides, acid halides and the like. These may be used alone or in combination of two or more.

  Examples of the softener used in the present invention include (S2) a quaternary ammonium salt having an alkyl group and / or an alkenyl group. Examples of the quaternary ammonium salt having an alkyl group and / or alkenyl group include compounds represented by the general formula (1).

General formula (1)

(In the formula, R ¹ is an alkyl group having 6 to 22 carbon atoms or an alkenyl group having 6 to 22 carbon atoms, and R ² and R ³ are (EO) _m (PO) _n H, carbon numbers 1 to 22). R ² and R ³ may be the same as or different from each other, X ⁻ is an anion, and E is An ethylene group, wherein P represents a propylene group, and the total of m and n is 1 to 60. The addition form of ethylene oxide and / or propylene oxide may be random or block, where m and n are Average number of moles added.)

  Specific examples of the quaternary ammonium salt represented by the general formula (1) include trimethyl monolauryl ammonium chloride, trimethyl monocetyl ammonium chloride, trimethyl monostearyl ammonium chloride, trimethyl monooleyl ammonium chloride, and trimethyl monobehenyl ammonium. Chloride, dimethyl dilauryl ammonium chloride, dimethyl dicetyl ammonium chloride, dimethyl distearyl ammonium chloride, dimethyl dioleyl ammonium chloride, dimethyl dibehenyl ammonium chloride, polyalkyleneoxy monomethyl dioleyl ammonium chloride, bis (polyalkyleneoxy) monomethyl monooleyl Ammonium chloride is mentioned.

The softeners used in the present invention, (S3) the following general formula (2) in component formula represented ^{(2) R 4 -A 1 -} (EO) m (PO) n -R 5
(In the formula, —A ¹ — represents —O— or —COO—, R ⁴ represents an alkyl group having 6 to 24 carbon atoms or an alkenyl group having 6 to 24 carbon atoms, and R ⁵ represents 6 carbon atoms. Represents an alkyl group having 24 to 24 carbon atoms, an alkenyl group having 6 to 24 carbon atoms, an alkyl group having 6 to 24 carbon atoms or an alkenyl group having 6 to 24 carbon atoms, or a hydrogen group, and R ⁴ and R ⁵ are They may be the same or different, E represents an ethylene group, P represents a propylene group, and the sum of m and n is 1 to 60, where m and n are the average number of moles added. )
Is mentioned.

  The compound represented by the general formula (2) is, for example, an alcohol having 6 to 24 carbon atoms, preferably 10 to 22 alcohols, or ethylene oxide in 1 mol of a fatty acid having 6 to 24 carbon atoms, preferably 10 to 22 carbon atoms, and It can be obtained by adding propylene oxide, and further, the alkylene oxide adduct is esterified with 1 mol of a fatty acid having 6 to 24 carbon atoms, preferably 10 to 22 carbon atoms, or 6 to 24 carbon atoms, preferably Can be obtained by etherification with 10 to 22 alcohols or 1 to 6 moles of halogenated alkyl having 6 to 24 carbon atoms, preferably 10 to 22 carbon atoms. The addition form of ethylene oxide and / or propylene oxide may be random or block, and is an alcohol having 6 to 24 carbon atoms, preferably 10 to 22 carbon atoms or 1 mol of fatty acid having 6 to 24 carbon atoms, preferably 10 to 22 carbon atoms. 1 to 60 mol, preferably 2 to 40 mol.

  The alcohol having 6 to 24 carbon atoms may be any of linear alcohol, branched chain alcohol, saturated alcohol, and unsaturated alcohol. Among these various alcohols, alcohols having 10 to 22 carbon atoms are preferable, and lauryl alcohol, myristyl alcohol, cetyl alcohol, stearyl alcohol, behenyl alcohol, and oleyl alcohol are particularly preferable. As the fatty acid having 6 to 24 carbon atoms, behenic acid, stearic acid, oleic acid, palmitic acid, lauric acid, capric acid, and caprylic acid are preferable. The alcohol having 6 to 24 carbon atoms and the fatty acid having 6 to 24 carbon atoms may be used alone or in combination of two or more.

  Specific examples of the compound represented by the general formula (2) include polyoxyethylene decyl ether, polyoxyethylene lauryl ether, polyoxyethylene myristyl ether, polyoxyethylene cetyl ether, polyoxyethylene stearyl ether, polyoxyethylene Ethylene oleyl ether, polyoxyethylene-2-ethylhexyl ether, polyoxyethylene isodecyl ether, polyoxyethylene tridecyl ether, polyoxyethylene isostearyl ether, polyoxyethylene hexyl phenyl ether, polyoxyethylene heptyl phenyl ether, polyoxy Ethylene octyl phenyl ether, polyoxyethylene nonyl phenyl ether, polyoxyethylene decyl phenyl ether, polyoxyethylene Undecyl phenyl ether, polyoxyethylene dodecyl phenyl ether, polyoxyethylene monolaurate, polyoxyethylene monostearate, polyoxyethylene monooleate, polyoxyethylene sorbitan monooleate, polyoxyethylene sorbitol tetraoleate, poly Oxyethylene glyceryl isostearate, polyoxyethylene polyoxypropylene-2-ethylhexyl ether, polyoxyethylene polyoxypropylene isodecyl ether, polyoxyethylene polyoxypropylene tridecyl ether, polyoxyethylene polyoxypropylene decyl ether, polyoxy Ethylene polyoxypropylene lauryl ether, polyoxyethylene polyoxypropylene myristyl ether Polyoxyethylene polyoxypropylene stearyl ether, polyoxyethylene polyoxypropylene lauric acid diester, polyoxyethylene polyoxypropylene myristic acid diester, polyoxyethylene polyoxypropylene cetyl acid diester, polyoxyethylene polyoxypropylene stearin Examples include acid diesters, oleic acid diesters of polyoxyethylene polyoxypropylene, and polyoxyethylene oleylamide. Furthermore, oleic acid ester of polyoxyethylene behenyl ether, oleic acid ester of polyoxyethylene stearyl ether, oleic acid ester of polyoxyethylene oleyl ether, oleic acid ester of polyoxyethylene cetyl ether, olein of polyoxyethylene lauryl ether Acid ester, oleic acid ester of polyoxyethylene polyoxypropylene behenyl ether, oleic acid ester of polyoxyethylene polyoxypropylene stearyl ether, oleic acid ester of polyoxyethylene polyoxypropylene oleyl ether, polyoxyethylene polyoxypropylene cetyl ether Oleic acid ester, oleic acid ester of polyoxyethylene polyoxypropylene lauryl ether Etc., and also the portion of the oleic acid ester, lauric acid ester, myristic acid ester, cetyl ester, stearic acid ester, may be another fatty acid esters such as behenic acid ester.

Measurement of molecular weight The molecular weight and molecular weight distribution of the polyamide polyamine / epihalohydrin resin and the polyamide polyamine polyurea / epihalohydrin resin in the examples were measured by GPC-MALS method in which a multi-angle light scattering detector was connected to GPC. The measurement conditions are as follows.
GPC body: LC1100 series manufactured by Agilent Technologies Inc. Column: SHODEX SB806M HQ manufactured by Showa Denko KK
Eluent: N / 10 phosphate buffer (pH 3) containing N / 10 sodium nitrate
Detector 1: Multi-angle light scattering detector DAWN manufactured by Wyatt Technology
Detector 2: Differential refractive index detector RI-101 manufactured by Showa Denko KK

Measurement of molecular weight distribution The aqueous resin solutions of Examples 1 to 13 and Comparative Examples 1 to 7 diluted to 5% were added to a centrifuge tube with an ultrafiltration membrane (Biomax PBCC 5,000 NMWL: manufactured by Millipore), respectively, at 6000 rpm Centrifugation was performed for 30 minutes. A component having a molecular weight of 5,000 or more was calculated from the fractionated solution amount and the resin solid content.
Measurement of intrinsic viscosity and Huggins constant Use of Ubbelohde viscometer for 1%, 0.5% and 0.2% 1N ammonium chloride aqueous solution of polyamide polyamine / epihalohydrin resin and polyamide polyamine / polyurea / epihalohydrin resin in the examples. Then, the reduced specific viscosity η _sp / C at a measurement temperature of 25 ° C. was determined, and the intrinsic viscosity [η] and the Huggins constant k ′ were determined.
η _sp / C = [η] + k '[η] ² × C
Here, C is the concentration, [η] is the intrinsic viscosity, and k ′ is a number called the Huggins constant, which is a constant determined by the type of polymer and the type of solvent, but is independent of the degree of polymerization. Therefore, if k ′ is known, [η] can be obtained from the concentration dependence of η _sp / C.

Storage Stability The storage stability at 40 ° C. of each of the wet paper strength improver aqueous solutions obtained in Examples 1 to 13 and Comparative Examples 1 to 7 was evaluated.
<Criteria for storage stability>
○: The viscosity of a resin aqueous solution held at 40 ° C. for 15 days at a solid content of 10% was within ± 10 mPa · s as compared to before holding.
Δ: Viscosity at a solid content of 10% of the resin aqueous solution held at 40 ° C. for 15 days is higher than ± 20 mPa · s compared to before holding, and is not gelled.
X: A gelled resin aqueous solution kept at 40 ° C. for 15 days.

Example 1
<Production of polyamide polyamine>
A four-necked round bottom flask equipped with a thermometer, reflux condenser, stirrer, and nitrogen inlet tube was charged with 104 g (1.01 mol) of diethylenetriamine as polyalkylenepolyamines A and 0.52 g (0.005 mol) of 95% sulfuric acid. While stirring, 146 g (1 mol) of adipic acid was added as aliphatic dibasic carboxylic acid B, and the temperature was raised while removing water produced outside the system in a nitrogen stream, followed by reaction at 175 ° C. for 4 hours. (Condensation 1), water was gradually added to adjust the solid content to 35% to obtain an aqueous polyamide polyamine solution.

<Production of Polyamide Polyamine-Epihalohydrin>
Epichlorohydrin C112g (1.21mol) was dripped at the polyamide polyamine aqueous solution obtained above over 30 minutes. At this time, the temperature of the reaction solution is kept at 25 ° C. or lower. After the dropping, the temperature was raised to 30 ° C. and kept at the same temperature for 4 hours (step 1). Next, water was added to make the solid content 32%, and after raising the temperature to 60 ° C. and reacting for 3 hours (step 2), 50 g of water and 5 g of 30% sulfuric acid were added and cooled. After cooling to near room temperature, a predetermined amount of acetic acid, which is a water-soluble carboxylic acid E, was added, the pH was adjusted with sulfuric acid, the solid content was adjusted with water, and a polyamide polyamine / epihalohydrin resin aqueous solution was obtained. Table 1 shows the content, pH, and solid content of the water-soluble carboxylic acid.

Examples 2-8
<Production of polyamide polyamine>
In the production of polyamide polyamine, diethylenetriamine as polyalkylenepolyamine A, adipic acid as aliphatic dibasic carboxylic acid B, temperature and reaction time conditions (condensation 1) except that the values described in Table 1 are used. This was synthesized in the same manner as in Example 1.
<Production of Polyamide Polyamine-Epihalohydrin>
In the production of polyamide polyamine-epihalohydrin, synthesis was performed in the same manner as in Example 1 except that epichlorohydrin as epihalohydrin C and acetic acid as water-soluble carboxylic acid E were set to the numerical values shown in Table 1.

Examples 9 and 11
<Production of polyamide polyamine>
In the production of polyamide polyamine, diethylenetriamine as polyalkylenepolyamines A, adipic acid as aliphatic dibasic carboxylic acid B, temperature and reaction time conditions (condensation 1) are as shown in Table 1, and sulfuric acid Was synthesized in the same manner as in Example 1 except that 0.65 g (0.005 mol) of 75% phosphoric acid was used instead of.
<Production of Polyamide Polyamine-Epihalohydrin>
In the production of polyamide polyamine-epihalohydrin, synthesis was performed in the same manner as in Example 1 except that epichlorohydrin as epihalohydrin C and formic acid as water-soluble carboxylic acid E were set to the numerical values shown in Table 1.

Example 10
<Production of polyamide polyamine>
In the production of polyamide polyamines, polyalkylene polyamines A are polyvalent amine mixtures (diethylenetriamine / tetraethylenepentamine = 1: 0.05 molar ratio), and aliphatic dibasic carboxylic acids B are dibasic acid ester mixtures (glutar). Dimethyl acid / dimethyl adipate = 1 / 8.29 molar ratio), the conditions of temperature and reaction time (condensation 1) are as shown in Table 1, and 75% phosphoric acid is added in an amount of 0.5% phosphoric acid instead of sulfuric acid. The synthesis was performed in the same manner as in Example 1 except that 65 g (0.005 mol) was used.
<Production of Polyamide Polyamine-Epihalohydrin>
In the production of polyamide polyamine-epihalohydrin, synthesis was performed in the same manner as in Example 1 except that epichlorohydrin as epihalohydrin C and formic acid as water-soluble carboxylic acid E were set to the numerical values shown in Table 1.

Example 12
<Production of polyamide polyamine polyurea>
In a four-necked round bottom flask equipped with a thermometer, reflux condenser, stirrer, and nitrogen inlet tube, 108 g (1.05 mol) of diethylenetriamine as polyalkylenepolyamines A and 0.65 g (0.005 mol) of 75% phosphoric acid were added. While charging and stirring, 146 g (1 mol) of adipic acid was added as aliphatic dibasic carboxylic acid B, and the temperature was raised while removing generated water out of the system under a nitrogen stream, followed by reaction at 175 ° C. for 3 hours. (Condensation 1). Subsequently, it cooled to 120 degreeC, urea 18g (0.3 mol) was added as ureas D, and it was made to react for 1 hour, removing the produced | generated ammonia out of the system (condensation 2). Water was gradually added to adjust the solid content to 35% to obtain a polyamide polyamine polyurea aqueous solution.

<Production of polyamide polyamine polyurea-epihalohydrin>
92.5 g (1 mol) of epichlorohydrin as epihalohydrins C was added dropwise to the aqueous polyamide polyamine polyurea solution obtained above over 30 minutes. At this time, the temperature of the reaction solution is kept at 25 ° C. or lower. After the dropping, the temperature was raised to 30 ° C. and kept at the same temperature for 4 hours (step 1). Then add water to bring the solids to 32%
The mixture was heated to 60 ° C. and reacted for 3 hours (step 2), and then cooled by adding 50 g of water and 5 g of 30% sulfuric acid. After cooling to near room temperature, a predetermined amount of formic acid was added as water-soluble carboxylic acids E, the pH was adjusted with sulfuric acid, the solid content was adjusted with water, and a polyamide polyamine polyurea / epihalohydrin resin aqueous solution was obtained. Table 1 shows the content, pH, and solid content of the water-soluble carboxylic acid.

Example 13
<Production of polyamide polyamine polyurea>
In the production of polyamide polyamine polyurea, diethylenetriamine as polyalkylene polyamine A, adipic acid as aliphatic dibasic carboxylic acid B, urea as urea D, conditions of temperature and reaction time (condensation 1, condensation 2) are shown in Table 1. The synthesis was performed in the same manner as in Example 12 except that the numerical values described in the above were used.

<Production of polyamide polyamine polyurea-epihalohydrin>
In the production of polyamide polyamine polyurea-epihalohydrin, synthesis was performed in the same manner as in Example 12 except that epichlorohydrin as epihalohydrin C and formic acid as water-soluble carboxylic acid E were set to the numerical values shown in Table 1.

Comparative Examples 1 to 3, Comparative Examples 5 and 6
<Production of polyamide polyamine>
In the production of polyamide polyamine, diethylenetriamine as polyalkylenepolyamine A, adipic acid as aliphatic dibasic carboxylic acid B, temperature and reaction time conditions (condensation 1) except that the values described in Table 1 are used. This was synthesized in the same manner as in Example 1.

<Production of Polyamide Polyamine-Epihalohydrin>
In the production of polyamide polyamine-epihalohydrin, synthesis was performed in the same manner as in Example 1 except that epichlorohydrin as epihalohydrin C and formic acid as water-soluble carboxylic acid E were set to the numerical values shown in Table 1.

Comparative Examples 4 and 7
<Production of polyamide polyamine polyurea>
In the production of polyamide polyamine polyurea, diethylenetriamine as polyalkylene polyamine A, adipic acid as aliphatic dibasic carboxylic acid B, urea as urea D, conditions of temperature and reaction time (condensation 1, condensation 2) are shown in Table 1. The synthesis was performed in the same manner as in Example 12 except that the numerical values described in the above were used.

<Production of polyamide polyamine polyurea-epihalohydrin>
In the production of polyamide polyamine polyurea-epihalohydrin, synthesis was performed in the same manner as in Example 12 except that epichlorohydrin as epihalohydrin C and formic acid as water-soluble carboxylic acid E were set to the numerical values shown in Table 1.

  Polyalkylene polyamine (A) / dibasic carboxylic acid (B) / epihalohydrin (C) / polyamide polyamine / epihalohydrin resin or polyamide polyamine polyurea / epihalohydrin resin obtained in Examples 1 to 13 and Comparative Examples 1 to 7 / Table 1 shows the molar ratio of urea (D) and the content of water-soluble carboxylic acid (E), and Table 2 shows the degree of cationization, intrinsic viscosity, Huggins constant, molecular weight, and molecular weight distribution.

Synthesis Example 1 Production of dry paper strength agent corresponding to acrylamide copolymer (P1) 483 g of ion-exchanged water in a 1 liter four-necked separable flask equipped with a stirrer, thermometer, reflux condenser and nitrogen gas inlet tube M1) 267 g (1.88 mol) of 50% acrylamide as the monomer, (M2) 1.5 g (9.5 mmol) of sodium methallyl sulfonate as the monomer, (M3) 5.2 g (0.04 mol) of itaconic acid as the monomer, ( M4) 76% dimethylaminoethyl methacrylate benzyl quaternary chloride aqueous solution 18.7 g (0.053 mol) and dimethylaminoethyl methacrylate 1.57 g (0.011 mol) as monomers, N, N-dimethyl as nonionic crosslinkable monomer Charge 1.2g (0.012mol) of acrylamide And then the pH was adjusted to 3.1 with 30% aqueous sulfuric acid. Next, the temperature inside the flask was adjusted to 61 ° C. in a constant temperature water bath under a nitrogen gas atmosphere, 4.56 g of 5% ammonium persulfate aqueous solution was added as a polymerization initiator, and the temperature was raised to 90 ° C. under a nitrogen gas atmosphere. One hour after adding the first polymerization initiator, 9.12 g of 5% ammonium persulfate aqueous solution was additionally added and reacted at the same temperature for another hour to obtain a dry paper strength agent composed of the acrylamide copolymer (P1). It was. The obtained dry paper strength agent 10% solution was subjected to B-type viscosity at 25 ° C. and molecular weight measurement by GPC-MALS, and the pH is shown in Table 3.

Synthesis Example 2 Production of Dry Paper Strength Agent Synthesis Example 1 was carried out in the same manner as Synthesis Example 1 except that (M4) monomer was not used. Table 3 shows the properties of the resulting papermaking paper strength enhancer.

Synthesis Example 3 Production of Softener Corresponding to Fatty Acid Amide Epihalohydrin Resin (S1) Into a 3 L four-necked round bottom flask equipped with a thermometer, reflux condenser, stirrer and dropping funnel, 103 g (1 mol) of diethylenetriamine as polyalkylene polyamines As a monocarboxylic acid having 6 to 24 carbon atoms, 559 g (2 mol) of palm oil oleic acid {oleic acid / linoleic acid / palmitic acid (mixing weight ratio 70/20/10)} was gradually added. The temperature was raised to 180 ° C., and reaction was performed for 3 hours while removing generated water out of the system to obtain an amide compound. The amount of residual amino groups of the obtained amide compound was 2 mmol / g.
Next, 100 g of the amide compound (0.16 mol as an amino group), 5 g of polyoxyethylene (45) stearylamine (the numbers in parentheses indicate the average number of moles added of polyoxyethylene), 100 g of water, and epichlorohydrin as epihalohydrins. Hydrin (5.9 g, 0.064 mol) was added at 50 ° C. and stirred for 30 minutes. Subsequently, after the reaction solution was reacted at 70 ° C. for 1 hour, the reaction solution was cooled and adjusted by adding water so that the solid content was 30% by mass, which corresponds to the fatty acid amide epihalohydrin resin (S1). A paper softener was obtained. Table 4 shows the evaluation results of the concentration, viscosity, melting point and particle size of the obtained paper softener.

<Preparation of handmade paper and evaluation results of paper quality>
Wet paper strength prepared in Examples 1 to 13 and Comparative Examples 1 to 7 on a paper stock having a concentration of 2.4% by mass adjusted from bleached kraft pulp (hardwood / conifer = 9/1) to a beating degree (CSF) of 400 The agent was added so that it might be 0.3 mass% with respect to pulp solid content. After stirring, paper was made with a square sheet machine to obtain hand-made paper with a basis weight of 80 g / m ² . Table 5 shows the wet tear length, specific burst strength, and Young's modulus of the obtained handmade paper.

  Prepared in the same manner as the above handmade paper except that 0.3% by mass of the wet paper strength agent prepared in Examples 1 to 13 was added to the pulp solid content and 0.2% of the dry paper strength agent was added. A handmade paper was obtained. Table 6 shows the wet tear length and specific burst strength of the obtained handmade paper.

  A wet paper strength agent prepared in Examples 1 to 13 was added in the same manner as the above handmade paper except that 0.3% by mass per pulp solid content was added and then a softening agent was added in an amount of 0.3%. A paper was obtained. Table 7 shows the wet tear length and Young's modulus of the obtained handmade paper.

Wet tear length: according to JIS P8135 Specific burst strength: according to JIS P8112 Young's modulus: manufactured by Nomura Corporation Ultrasonic propagation velocity V was measured with an orientation measuring instrument SST-2500, and Young's modulus was obtained from the following formula. The lower the number, the more flexible the paper. Relative notation was given assuming that no chemical-added paper was 100.
Young's modulus ∝ρV ² (ρ: density)

<Paper making conditions>
Pulp used: Bleached kraft pulp (Hardwood / Conifer = 9/1), Degree of beating (CSF) 400
Drying conditions: 100 ° C.-100 seconds (drum dryer), pressing conditions: 4.2 kgf / cm ² -5 minutes Basis weight: 80 g / m ²

表６中の略号の説明
セルロース誘導体１・・・水溶性セルロース誘導体（Ｐ２）に相当する乾燥紙力剤１％水溶液の３ｍＰａ・ｓ、エーテル化度０．７５
セルロース誘導体２・・・水溶性セルロース誘導体（Ｐ２）に相当する乾燥紙力剤。１％水溶液の１５ｍＰａ・ｓ、エーテル化度０．４

Explanation of abbreviations in Table 6 Cellulose derivative 1 ... 3 mPa · s of 1% aqueous solution of dry paper strength equivalent to water-soluble cellulose derivative (P2), degree of etherification 0.75
Cellulose derivative 2... A dry paper strength agent corresponding to the water-soluble cellulose derivative (P2). 1 m aqueous solution of 15 mPa · s, degree of etherification 0.4

表7中の略号の説明
柔軟剤１・・・柔軟剤（Ｓ３）に相当するオレイン酸ＥＯ（４）ＰＯ（１２）オレイルエーテル。ＥＯはエチレンオキサイド、ＰＯはプロピレンオキサイド、（ ）内の数値は平均付加モル量を示している。
柔軟剤２・・・柔軟剤（Ｓ２）に相当するジオレイルジメチルアンモニウムクロライド

Explanation of abbreviations in Table 7 Softener 1 ... oleic acid EO (4) PO (12) oleyl ether corresponding to softener (S3). EO is ethylene oxide, PO is propylene oxide, and the numerical value in () indicates the average added molar amount.
Softener 2 ... Dioleyldimethylammonium chloride equivalent to softener (S2)

  As is apparent from Table 5, the internal paper containing the wet paper strength agents of Examples 1 to 13 of the present invention provides a paper excellent in wet paper strength.

  Further, as is clear from Table 6, the papers containing the wet paper strength agents and the dry paper strength agents of Examples 1 to 13 are excellent in wet paper strength and dry paper strength.

  Further, as is apparent from Table 7, the papers containing the wet paper strength agents and the softening agents of Examples 1 to 13 provide papers with excellent wet paper strength and flexibility.

Claims (5)

(A) A resin obtained by reacting a polyalkylene polyamine and a dibasic carboxylic acid with a polyamide polyamine and an epihalohydrin, the polyalkylene polyamine being 28 to 33 mol%, a dibasic carboxylic acid Polyamide polyamine / epihalohydrin resin obtained by reaction at a ratio of 28 to 33 mol% and epihalohydrin 34 to 40 mol%, or
(B) a resin obtained by reacting a polyalkylene polyamine, a dibasic carboxylic acid and a urea, and a polyamidopolyamine polyurea and an epihalohydrin, wherein the polyalkylene polyamine is 30 to 35 mol%, Containing a polyamide polyamine polyurea / epihalohydrin resin obtained by reaction at a ratio of 29 to 34 mol% of dibasic carboxylic acids, 3.9 to 15 mol% of ureas, and 24 to 36 mol% of epihalohydrins,
(1) Intrinsic viscosity is 0.13 to 0.40 dL / g,
(2) The Huggins constant is 0.50 to 1.00,
(3) The cationization degree at pH 10 is 1.2 to 2.6 meq / g per solid content,
(4) The weight average molecular weight is 500,000-3 million,
(5) A wet paper strength improver characterized in that the proportion of components having a weight average molecular weight of 50,000 or more is 50% by mass or more. The aqueous solid content of the wet paper strength improver is 20 to 31% by mass,
The wet paper strength improver has a pH of 2.6 to 4.0,
The wet paper strength improver according to claim 1, comprising 0.05 to 2.00% by mass of a water-soluble carboxylic acid. The wet paper strength improver according to claim 1 or 2 is 0.01 to 2.00% by mass, and the dry paper strength improver (P1) or (P2) is 0.05 to 3. Paper containing 00% solids by mass.
(P1) An acrylamide copolymer-based dry paper strength improver (M1) (meth) acrylamide obtained by polymerizing the following monomers (M1) to (M3) and the monomer (M4) as necessary: 80 to 95 mol %,
(M2) (meth) allylsulfonic acid and its salts are 0.05 to 4.00 mol%,
(M3) 0.1 to 18.0 mol% of a vinyl monomer having a carboxyl group and salts thereof
(M4) 0.1-18.0 mol% of vinyl monomer having tertiary amino group and / or vinyl monomer having quaternary ammonium salt
(P2) Water-soluble cellulose derivative The wet paper strength improver according to claim 1 or 2 is 0.01 to 2.00 solids mass%, and at least one softener of the following (S1) to (S3) is 0.05 to 3. Paper containing 00% solids by mass.
(S1) Fatty acid amide epihalohydrin resin (S2) Quaternary ammonium salt general formula (1) having an alkyl group and / or an alkenyl group represented by the following general formula (1)

(In the formula, R ¹ is an alkyl group having 6 to 22 carbon atoms or an alkenyl group having 6 to 22 carbon atoms, and R ² and R ³ are (EO) _m (PO) _n H, carbon numbers 1 to 22). R ² and R ³ may be the same as or different from each other, X ⁻ is an anion, and E is An ethylene group, wherein P represents a propylene group, and the total of m and n is 1 to 60. The addition form of ethylene oxide and / or propylene oxide may be random or block, where m and n are Average number of moles added.)
(S3) Component general formula (2) represented by the following general formula (2) R ⁴ —A ¹ — (EO) _m (PO) _n —R ⁵
(In the formula, —A ¹ — represents —O— or —COO—, R ⁴ represents an alkyl group having 6 to 24 carbon atoms or an alkenyl group having 6 to 24 carbon atoms, and R ⁵ represents 6 carbon atoms. Represents an alkyl group having 24 to 24 carbon atoms, an alkenyl group having 6 to 24 carbon atoms, an alkyl group having 6 to 24 carbon atoms or an alkenyl group having 6 to 24 carbon atoms, or a hydrogen group, and R ⁴ and R ⁵ are They may be the same or different, E represents an ethylene group, P represents a propylene group, and the sum of m and n is 1 to 60, where m and n are the average number of moles added. ) The paper according to claim 3 or 4, wherein the paper is sanitary paper or hybrid paper.