JP2017210702A - Sizing agent composition and method for producing paper - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a new sizing agent composition exhibiting excellent sizing performance even when used not only in a coating method but also in an addition method to a paper-making system; a method for producing paper using the sizing agent; and a method for producing paperboard.SOLUTION: A sizing agent contains a compound (A) obtained by reaction polyamide, which is obtained by polycondensation of specific polyalkylene polyamine (a), polycarboxylic acids (b) and fatty acid (c) so that the mol number of the carboxylic group of the polycarboxylic acids (b) is 10-60% and the mol number of the carboxylic group of the fatty acid (c) is 30-70% with respect to the mol number of the amino group of the polyalkylene polyamine (a), and a compound having an epoxy group, and at least one metal element (B) selected from potassium and sodium, where a content of the metal element (B) with respect to the sizing agent is 0.05-5 mass%.SELECTED DRAWING: None

Description

  The present invention relates to a sizing composition and a method for producing paper, and more particularly, to a sizing composition containing a reaction product of a specific polyamide and a compound having an epoxy group, and a specific metal element, and a sizing effect. The present invention relates to a method for producing excellent paper, particularly paperboard.

  As a sizing agent used for imparting sizing properties to paper, a rosin sizing agent, an AKD sizing agent, an ASA sizing agent, a styrene-maleic acid sizing agent, or a styrene-acrylic sizing agent is preferable Are known.

  However, in recent years, in the paper manufacturing process, (1) increase in papermaking pH due to the use of calcium carbonate, which is an inexpensive filler, (2) increase in used paper ratio, or (3) closed papermaking system to reduce papermaking wastewater. The above-described conventional sizing agents are difficult to achieve the effect, or papermaking stains are problematic.

  On the other hand, the inventors of the present application apply a coating liquid containing a surface sizing agent composed of a reaction product of a specific polyamide compound and a compound having an epoxy group, and an aluminum compound to a paperboard base paper. It has also been found that paperboard with greatly improved size performance can be produced (Patent Document 1).

  On the other hand, the reaction product of the aliphatic modified aminopolyamide and epichlorohydrin is added to the dryer by adding it to the pulp slurry or wet paper before being fed to the dryer part in the papermaking process. It is known that the peelability of paper can be improved (Patent Document 2).

  However, compared to the surface coating method in which the entire amount of the sizing agent is retained on the paper, the paper making system can be added with the sizing agent having the same composition as the surface sizing agent found by the present inventors as described above. The pH, electrical conductivity, and anionic contaminants in the system affect the fixing of the sizing agent to the pulp, or inhibit the expression of the size, and the size effect is greatly inferior compared to when the same amount is applied to the surface. Thus, it cannot be used until other conventional sizing agents are replaced.

  Addition to a papermaking system that is much thinner than the surface coating system is less likely to achieve an interaction effect with the aluminum compound than the coating system.

  Therefore, attempts to improve the size effect by adding a reaction product of a polyamide compound and a compound having an epoxy group to a papermaking system have not been studied so far.

Japanese Patent No. 5455102 JP 59-30997

  The present invention provides a novel sizing composition that exhibits excellent sizing performance when used not only in a coating system but also in an addition system to a papermaking system, and a paper manufacturing method using the sizing composition. The issue is to provide.

As a result of intensive studies in view of the above-described problems, the present inventors have found that a sizing composition containing a reaction product of a specific polyamide and a compound having an epoxy group and a specific metal element is contained in the pulp slurry. It has been found that an excellent size effect is exhibited even when added and used, and the present invention has been completed.
That is, the present invention
(1) Polyalkylene polyamine (a), polyvalent carboxylic acid (b) and fatty acid (c) having 3 or more amino groups in one molecule are added to the number of moles of amino groups of polyalkylene polyamine (a). A polyamide obtained by polycondensation in a ratio such that the number of moles of carboxyl groups of the polyvalent carboxylic acids (b) is in the range of 10 to 60% and the number of moles of carboxyl groups of the fatty acid (c) is in the range of 30 to 70%; A sizing composition comprising a compound (A) obtained by reacting an epoxy group-containing compound with at least one metal element (B) selected from potassium and sodium, and a sizing composition The sizing agent composition, wherein the content of the metal element (B) is 0.05 to 5% by mass relative to 100% by mass of the product,
(2) The sizing composition as described in (1) above, wherein the content of the metal element (B) is 0.1 to 10% by mass relative to 100% by mass of the compound (A),
(3) A method for producing paper, comprising adding the sizing composition according to (1) or (2) above and a primary and / or secondary amino group-containing vinyl polymer to a pulp slurry,
It is.

  ADVANTAGE OF THE INVENTION According to this invention, even when it uses as a sizing agent component which adds the reaction material of a polyamide and the compound which has an epoxy group to a pulp slurry, the sizing agent composition which can exhibit the outstanding sizing performance can be provided. In particular, when used in combination with a primary and / or secondary amino group-containing vinyl polymer, it is possible to provide a method for producing paper that exhibits excellent size performance.

  The sizing composition of the present invention comprises a polyalkylene polyamine (a) having 3 or more amino groups in one molecule, a polyvalent carboxylic acid (b) and a fatty acid (c). The polycondensation is performed in such a ratio that the number of moles of the carboxyl group of the polyvalent carboxylic acid (b) is 10 to 60% and the number of moles of the carboxyl group of the fatty acid (c) is 30 to 70% with respect to the number of moles of the group. A sizing composition comprising a compound (A) obtained by reacting a polyamide obtained by reacting with a compound having an epoxy group, and at least one metal element (B) selected from potassium and sodium. And content converted into the metal element (B) with respect to 100 mass% of sizing agent compositions is 0.05-5 mass%, It is characterized by the above-mentioned.

  Examples of the polyalkylene polyamine (a) having 3 or more amino groups in one molecule include diethylenetriamine, triethylenetetramine, tetraethylenepentamine, pentaethylenehexamine, hexaethyleneheptamine, dipropylenetriamine, and tripropylenetetramine. Among these, diethylenetriamine, triethylenetetramine, and tetraethylenepentamine are preferable, and diethylenetriamine is particularly preferable. These need to be able to form a polyamide by reacting with polyvalent carboxylic acids (b) and fatty acids (c). The polyalkylene polyamine (a) may be used alone or in combination of two or more.

  Examples of the polyvalent carboxylic acids (b) include malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, brassylic acid, dodecanedioic acid, terephthalic acid, maleic acid and the like. Dicarboxylic acids; tricarboxylic acids such as citric acid, trimellitic acid, butanetricarboxylic acid, and the like, and dicarboxylic acids having 4 to 10 carbon atoms and / or derivatives thereof are preferable. Examples of the derivatives include monoesters, diesters, acid anhydrides, and acid halides of the polyvalent carboxylic acids described above. Examples of monoesters and diesters of polyvalent carboxylic acids include esters of lower alcohols (methanol, ethanol, propanol) having 1 to 5 carbon atoms, particularly preferably 1 to 3 carbon atoms, and polyvalent carboxylic acids. it can. Examples of the acid anhydride include an intramolecular dehydration condensate of a free acid, a lower carboxylic acid, preferably a condensate of a lower carboxylic acid having 1 to 5 carbon atoms and a polyvalent carboxylic acid. Examples of the acid halide include acid chloride. Particularly preferable polyvalent carboxylic acids (b) include adipic acid, maleic acid and / or derivatives thereof. These need to be able to form a polyamide by reacting with the polyalkylene polyamine (a). The polyvalent carboxylic acids (b) can be used alone or in combination of two or more.

  The fatty acid (c) may be saturated or unsaturated, and specifically includes dodecanoic acid having 12 carbons (lauric acid), tetradecanoic acid having 14 carbons (myristic acid), and 15 carbons. Pentadecanoic acid (pentadecylic acid), carbon number 16 hexadecanoic acid (palmitic acid), 9-hexadecenoic acid (palmitoyl acid), carbon number 17 heptadecanoic acid (margaric acid), carbon number 18 octadecanoic acid (stearic acid) Cis-9-octadecenoic acid (oleic acid), 11-octadecenoic acid (vaccenic acid), cis, cis-9,12-octadecadienoic acid (linoleic acid), 9,12,15-octadecantrienoic acid ((9 , 12,15) -linolenic acid), 6,9,12-octadecatrienoic acid ((6,9,12) -linolenic acid), 9,11,13-o Tadecatrienoic acid (eleostearic acid), 19-carbon nonadecanoic acid (tuberculostearic acid), 20-carbon icosanoic acid (arachidic acid), 8,11-icosadienoic acid, 5,8,11-icosatrienoic acid, 5 , 8,11,14-icosatetraenoic acid (arachidonic acid), docosanoic acid (behenic acid) having 22 carbon atoms, and esters or acid halides of these fatty acids. Among these, the fatty acid (c) is preferably a saturated fatty acid, and more preferably a fatty acid having 16 to 22 carbon atoms. These need to be able to form a polyamide by reacting with the polyalkylene polyamine (a). The fatty acid (c) can be used alone or in combination of two or more.

  In the polyamide, the number of moles of the carboxyl group of the polycarboxylic acid (b) is 10 to 60% and the number of moles of the carboxyl group of the fatty acid (c) with respect to the number of moles of the amino group of the polyalkylene polyamine (a). Is obtained by polycondensation at a ratio included in the range of 30 to 70%. In addition, when using a carboxylic acid derivative, it becomes the ratio in the mol number of the carboxyl group in the state which is not a derivative.

  When the number of moles of the carboxyl group of the polyvalent carboxylic acid (b) is less than 10% relative to the number of moles of the amino group of the polyalkylene polyamine (a), the number of amino groups in the produced polyamide compound (I) increases and hydrophilicity is increased. Since the number of sites increases and the molecular weight decreases, the desired size effect cannot be obtained. On the other hand, if it exceeds 60%, the number of cationic sites that can be fixed on cellulose decreases, and as a result, the desired size effect cannot be obtained. More preferably, it is 20 to 53%.

  When the number of moles of the carboxyl group of the fatty acid (c) is less than 30% with respect to the number of moles of the amino group of the polyalkylene polyamine (a), the number of hydrophobic sites derived from the fatty acid (c) is reduced, so I can't get it. On the other hand, if it exceeds 70%, the produced polyamide compound (I) has few amino groups, and the number of cationic sites that can be fixed on cellulose is reduced. As a result, the desired size effect cannot be obtained. More preferably, it is 33 to 67%.

  The reaction of the polyalkylene polyamine (a) with the polyvalent carboxylic acids (b) and the fatty acid (c) is carried out by heating them to 100 to 200 ° C. to cause dehydration condensation. The reaction time is preferably 0.5 to 10 hours, and more preferably 2 to 6 hours. There is no limitation on the method of mixing the polyalkyleneamine (a) with the polyvalent carboxylic acid (b) and the fatty acid (c) during the reaction, and the polyalkylenepolyamine (a) is mixed with the polyvalent carboxylic acid (b) and the fatty acid (c And a method of proceeding the reaction by mixing the fatty acid (c) with a reaction product of the polyalkylene polyamine (a) and the polyvalent carboxylic acid (b). The catalyst for the amidation reaction may not be particularly used, but as the catalyst for the amidation reaction, sulfonic acids such as sulfuric acid, benzenesulfonic acid and paratoluenesulfonic acid, or a catalyst usually used for the amidation reaction are used. Also good. The amount used is preferably 0.005 to 0.1 mol, and more preferably 0.01 to 0.05 mol, relative to 1 mol of the polyalkylene polyamine (a).

  Examples of the compound having an epoxy group used for obtaining the reaction product (A) of the polyamide and the compound having an epoxy group contained in the sizing composition of the present invention include epichlorohydrin and epibromohydrin. Such as epihalohydrin, ethylene oxide, alkylene oxide such as butylene oxide, and styrene oxide. Among these, epichlorohydrin is preferable.

  The reaction product (A) of the polyamide and the compound having an epoxy group may be produced by any method as long as it is finally obtained as a stable aqueous dispersion. It is preferably obtained by adding an emulsifier and hot water into a product to obtain an aqueous dispersion, and adding and reacting a compound having an epoxy group with heating. Although there is no restriction | limiting in particular in the reaction ratio of polyamide and the compound which has an epoxy group, It is preferable to make 50-150 mol% of compounds which have an epoxy group with respect to the residual amino group of a polyamide compound.

  A known emulsifier can be appropriately used as the emulsifier. Examples of the emulsifier include nonionic emulsifiers such as fatty acid sorbitan esters, fatty acid polyglycol esters, fatty acid amides, and various polyalkylene oxide type nonionic surfactants having 4 to 20 carbon atoms in the alkyl group and / or alkenyl group. A long-chain alkylamine salt having 4 to 20 carbon atoms in the alkyl group and / or alkenyl group, polyoxyalkyleneamine, tetraalkyl quaternary ammonium salt, trialkylbenzyl quaternary ammonium salt, alkylimidazolium salt, alkylpyridinium Examples include cationic emulsifiers such as salts, alkyl quinolium salts, alkyl phosphonium salts, and alkyl sulfonium salts, and amphoteric surfactants such as various betaine surfactants.

  Among these, as the emulsifier, polyalkylene oxide type nonionic surfactants are preferable. Specifically, fatty acid alkylene oxide sorbitan ester, polyoxyalkylene fatty acid ester, polyoxyalkylene fatty acid amide, polyoxyalkylene fatty alcohol , Polyoxyalkylene aliphatic amine, polyoxyalkylene aliphatic mercaptan, polyoxyalkylene alkyl ether, polyoxyalkylene alkyl aryl ether and the like. As the emulsifier, an alkylene oxide adduct excellent in emulsification dispersibility is preferable. Further, 10 to 100 mol is preferably added as an alkylene oxide per molecule of the emulsifier, and 30 to 60 mol is particularly preferable. It is particularly preferable that the alkylene group of the alkylene oxide has 8 to 18 carbon atoms.

  The emulsifier can be used alone or in combination of two or more thereof, and the amount used thereof is 1 to 20 parts by mass with respect to 100 parts by mass of polyamide while suppressing foaming properties. It is preferable for increasing dispersibility, and more preferably 1 to 10 parts by mass.

  Moreover, when obtaining the reaction product (A) of the polyamide and the compound having an epoxy group, for example, the dispersibility when the polyamide is dispersed in water and / or the reaction product (A) of the polyamide and the compound having an epoxy group. In order to enhance the storage stability, an organic solvent such as isopropyl alcohol may be used as long as the size of the present invention is not impaired. The amount of the organic solvent used is preferably 1 to 10% by mass relative to the solid content of the reaction product (A) of the polyamide and the compound having an epoxy group.

  In the sizing composition of the present invention, in addition to the reaction product (A) of the polyamide and the epoxy group-containing compound (A), at least one metal element (B) selected from potassium and sodium is contained in 100% by mass of the sizing composition. On the other hand, it is essential to contain in 0.05-5 mass%.

  The metal element (B) is considered to contribute to the dispersion stabilization and size performance of the reaction product (A) of the polyamide and the compound having an epoxy group, but the mechanism has been elucidated in detail. Absent. When the content of the metal element (B) with respect to the sizing agent composition is less than 0.05% by mass, the fixing to the pulp and the expression of the size are hindered due to the influence of impurities in the papermaking system. The size effect cannot be obtained. Moreover, even if it contains in a sizing agent composition exceeding 5 mass%, the further improvement effect of sizing property will not be acquired and there exists a concern about the influence on papermaking type | system | group. It is preferable to contain in 0.2-2.0 mass%, and it is more preferable to contain in 0.2-1.0 mass%.

  Examples of the metal compound that gives at least one metal element (B) selected from potassium and sodium include hydroxides, carbonates and sulfates thereof. In particular, potassium hydroxide and sodium hydroxide are preferable.

  The mass ratio of the metal element (B) to the reaction product (A) of the polyamide and the compound having an epoxy group is preferably 0.1 to 10% in order to sufficiently exhibit the size effect. More preferably, it is 0.1-5%, More preferably, it is 0.9-2%.

  As long as the sizing composition of the present invention does not impair the effects of the present invention and does not affect the stability during storage, etc., other antifoaming agents, thickeners, preservatives, rust prevention Various additives such as an agent, a pH adjuster, a filler, an antioxidant, a filler, and a dye may be added.

  The sizing agent composition of the present invention can be used for production of various known papers (including paperboard). The method of use is not particularly limited, and can be applied to any method such as addition to a papermaking system (in a pulp slurry), coating on a paper surface, impregnation or spraying. Compared to conventional emulsion sizing agents such as rosin, AKD and ASA, the dispersion stability in the papermaking system is superior, so there is less concern about contamination, and there is little rise in sizing after papermaking over time and quality control is possible. Therefore, it is preferable from the viewpoint of operability especially in addition to a papermaking system.

  The sizing agent composition of the present invention is usually added in an amount of 0.03 to 0.5 mass% as a solid content with respect to the dry mass of the pulp slurry, although it depends on the type of paper or paperboard and the required size performance. Thus, a desired size effect can be obtained.

  By adding the sizing composition of the present invention, and preferably the primary and / or secondary amino group-containing vinyl polymer, to the pulp slurry separately or in advance, the paper is further improved in sizing (paperboard Including) can be manufactured. The addition amount of the primary and / or secondary amino group-containing vinyl polymer is not particularly limited, but is preferably 0.01 to 0.3% by mass in terms of solid content with respect to the dry mass of the pulp slurry. It is preferable that the solid content mass ratio of the primary and / or secondary amino group-containing vinyl polymer to the product is 30 to 100.

  The primary and / or secondary amino group-containing vinyl polymer refers to a polymer obtained by polymerizing vinyl monomers and having at least a primary or secondary amino group-containing vinyl monomer as a structural unit. It is preferable to have 10 mol units or more of primary and / or secondary amino group-containing vinyl monomers as structural units.

  Examples of the primary and / or secondary amino group-containing vinyl polymer include diallylamine homopolymer, a copolymer of diallylamine and a monomer copolymerizable with diallylamine such as (meth) acrylamide, and (meth) acrylamide as a polymerization component. Examples thereof include a polymer obtained by Hoffmann reaction or Mannich reaction, and a polymer obtained by hydrolyzing a polymer having N-vinylformamide as a polymerization component, and these may be used alone or in combination of two or more. Among these, a copolymer of diallylamine and (meth) acrylamide and a cation-modified (meth) acrylamide polymer by Hofmann decomposition reaction of polyacrylamide are preferable, and a copolymer of diallylamine and (meth) acrylamide is more preferable.

  There is no restriction | limiting in particular as a polymerization method of the said primary and / or secondary amino group containing vinyl polymer, A conventionally well-known method is employable.

  The sizing agent of the present invention can be used in combination with the primary and / or secondary amino group-containing vinyl polymer described above, and in order to impart other necessary performance to paper or paperboard, As long as the effect is not impaired, other sizing agents, dry paper strength enhancers, wet paper strength enhancers, coagulants, retention agents and other papermaking chemicals, starch, fillers and other functional additives are used in combination. It doesn't matter.

  Examples of paper that can be used for the sizing composition of the present invention include paper and paperboard, such as coated base paper, PPC base paper, ink jet paper, book paper, photo base paper, pressure sensitive base paper, thermal base paper, and newsprint paper. Examples include printing / information paper, packaging paper such as kraft paper, pure white roll paper, glassine paper, liner base paper, white board paper, core base paper, paper tube base paper, gypsum board base paper, flame retardant paper, and the like.

  Examples of the present invention will be described below. Note that the present invention is not limited to these embodiments. In each example, “%” means “% by mass” unless otherwise specified.

(Synthesis of sizing agent)
Synthesis example 1
In a separable flask having a thermometer, a condenser, and a stirrer, diethylenetriamine (1 mol) as polyalkylene polyamine (a), adipic acid (0.5 mol) as polyvalent carboxylic acids (b), maleic anhydride (0.3 mol) ) And heated to 130 ° C., and then added with stearic acid cherry (manufactured by NOF, stearic acid / palmitic acid mixture, 1.1 mol) as the fatty acid (c), heated to 170 ° C., and produced water The reaction was carried out at 170 ° C. for 6 hours while removing 800 g, to obtain 800 g of polyamide with a solid content of 100%.

  Into a separable flask having a thermometer, a condenser, and a stirrer, 100.0 g of the polyamide obtained above was charged, heated to 130 ° C. with stirring, and melted by heating. After confirming melting, a nonionic emulsifier (Newcol 2360, Nippon Emulsifier Co., Ltd., 3.0 g) was added, followed by hot water (80 ° C., 400.5 g), followed by isopropyl alcohol (5 0.0 g), 48% aqueous potassium hydroxide solution (6.2 g), and epichlorohydrin (100 mol%, 11.9 g based on the theoretical residual amino group of the polyamide compound) were added and reacted at 80 ° C. for 2 hours. Then, it cooled and ion-exchange water was added so that it might become 20% of solid content, and the size composition was obtained.

Synthesis Examples 2 to 11
Synthesis Example 1 except that the type of polyalkylene polyamine, the type and amount of polyvalent carboxylic acid (b), the amount of stearic acid sakura as a fatty acid, and the type and amount of potassium or sodium compound were changed as shown in Table 1. Was synthesized in the same manner as above.

Comparative Synthesis Example 12
Synthesis was performed in the same manner as in Synthesis Example 1 except that the 48% potassium hydroxide aqueous solution (6.2 g) of Synthesis Example 1 was changed to a sulfuric acid band (8.0 g).

(Size evaluation 1)
Canadian standard freeness (330 cc), corrugated waste paper pulp adjusted to have ash content in paper (15% by mass), and the sizing agent obtained as described above with respect to the pulp (0.20% by mass) After adding and diluting to 0.8% with water having an electric conductivity of 100 mS / m, NR12MLS (polymer retention agent, manufactured by Hymo Co., Ltd., 0.03% by mass) was added. Using this pulp slurry, the paper was hand-made with a noble and wood sheet machine to a basis weight of 80 g / m ^2, and dried with a drum dryer at 100 ° C. for 80 seconds. The obtained paper was conditioned for 24 hours in a constant temperature and humidity chamber at 23 ° C. and 50% RH, and then measured for a Cobb size of 120 seconds. The results are shown in Table 1.
120 seconds Cobb: Conforms to JIS P-8140. It shows that it is excellent in the size effect, so that a numerical value is small.

Explanation of annotations and abbreviations in the table * Aluminum conversion DETA: Diethylenetriamine TEPA: Tetraethylenepentamine KOH: Potassium hydroxide NaOH: Sodium hydroxide

By comparing Examples 1 to 6 and Comparative Examples 1 and 2, the polyalkylene polyamine (a), the polyvalent carboxylic acids (b), and the fatty acid (c) are converted into the number of moles of amino groups of the polyalkylene polyamine (a). On the other hand, it turns out that the sizing agent composition made into the ratio by which the mol number of the carboxyl group of polyhydric carboxylic acid (b) is contained in the range of 10 to 60% is excellent in a size effect.

By comparing Examples 1 to 6 with Comparative Examples 3 to 4, the polyalkylene polyamine (a), the polyvalent carboxylic acid (b), and the fatty acid (c) are converted into the number of moles of amino groups of the polyalkylene polyamine (a). On the other hand, it can be seen that a sizing agent composition having a ratio in which the number of moles of the carboxyl group of the fatty acid (c) falls within the range of 30 to 70% is excellent in size effect.

By comparing Examples 1 and 4 with Comparative Examples 5-6,
It can be seen that a sizing composition containing a metal element of either potassium or sodium in the range of 0.05 to 5 wt% is excellent in size effect. Further, by comparing Comparative Example 7, it can be seen that the sizing composition containing potassium and sodium metal elements is excellent in size effect.

(Synthesis of secondary amino group-containing polymer)
A separable flask having a thermometer, a condenser, and a stirrer is charged with diallylamine (15.5 g), 50% aqueous acrylamide solution (34.1 g), and ion-exchanged water (171.6 g), and the pH is adjusted to 3 with concentrated hydrochloric acid. After adjusting to .6 and performing nitrogen substitution, ammonium persulfate (0.12 g) was charged at 60 ° C. and held at 60 ° C. for 7 hours. Ion exchange water was added to obtain a secondary amino group-containing polymer having a polymer concentration of 15%.

(Synthesis of primary amino group-containing polymer)
A separable flask having a thermometer, a condenser, and a stirrer was charged with a 50% aqueous acrylamide solution (72 g) and ion-exchanged water (160 g), purged with nitrogen, and then stirred at 70 ° C. with ammonium persulfate (0. 13 g) was added and held at 90 ° C. for 3 hours. Subsequently, it cooled to 25 degreeC and ion-exchange water was added, and polyacrylamide with a polymer concentration of 15% was adjusted. Next, an aqueous solution in which sodium hypochlorite (30 g) having an effective chlorine concentration of 12% and 48% potassium hydroxide (7 g) was mixed was added dropwise at 25 ° C. with stirring. After completion of dropping, the mixture was kept at 25 ° C. for 1 hour, and the pH of the reaction solution was adjusted to 4.5 using dilute hydrochloric acid to obtain a primary amino group-containing polymer by Hofmann decomposition reaction having a polymer concentration of 10%.

(Size evaluation 2)
Instead of NR12MLS (polymer retention agent, manufactured by Hymo Co., Ltd.) not containing the primary and / or secondary amino group-containing vinyl polymer of Example 1, the secondary amino group-containing polymer or the primary amino group-containing compound synthesized above was used. Size evaluation was performed in the same manner as size evaluation 1 except that the polymer was added. The results are shown in Table 2.

By contrasting Example 1 with Examples 7-8,
It turns out that the paper which was further excellent in sizing degree is obtained by using together the size agent in this invention, and a primary and / or secondary amino group containing vinyl polymer.

Claims (3)

  A polyalkylene polyamine (a) having 3 or more amino groups in one molecule, a polyvalent carboxylic acid (b) and a fatty acid (c) can be added to the number of moles of amino groups of the polyalkylene polyamine (a). A polyamide obtained by polycondensation at a ratio such that the number of moles of the carboxyl group of the monovalent carboxylic acid (b) is 10 to 60% and the number of moles of the carboxyl group of the fatty acid (c) is 30 to 70%, and an epoxy group A sizing composition comprising a compound (A) obtained by reacting a compound having a valence of at least one metal element (B) selected from potassium and sodium, and 100 masses of the sizing composition. The sizing agent composition is characterized in that the content of the metal element (B) with respect to% is 0.05 to 5% by mass.   The sizing composition according to claim 1, wherein the content of the metal element (B) is 0.1 to 10% by mass relative to 100% by mass of the compound (A).   A method for producing paper, comprising adding the sizing composition according to claim 1 or 2 and a primary and / or secondary amino group-containing vinyl polymer to a pulp slurry.