JP2003089995A - Sizing agent for making paper - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a sizing agent which is used for making paper, contains a substituted cyclic dicarboxylic acid anhydride dispersed therein in a good dispersion stability without using an oil-in-water type surfactant or the like and can impart an excellent sizing performance to paper. SOLUTION: This sizing agent for making paper comprises (A) a substituted succinic acid anhydride and (B) a cationic (meth)acrylamide copolymer prepared by copolymerizing (1) a hydrophobic (meth)acrylic alkyl asters monomer, (2) a cationic monomer with (3) (meth)acrylamide.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a sizing agent for papermaking. More specifically, it relates to a papermaking sizing agent comprising a substituted succinic anhydride and a cationic water-soluble copolymer.

[0002]

2. Description of the Related Art Conventionally, rosin-based sizing agents such as rosin and reinforced rosin have been widely used as paper-making sizing agents, but these rosin-based sizing agents themselves are difficult to fix on cellulose fibers. Therefore, the sulfuric acid band had to be used together. Since a sulfuric acid band is used in combination, papermaking inevitably occurs in an acidic region, there is a problem that quality deterioration of the papermaking is large, wastewater treatment becomes complicated, papermaking equipment is corroded, and an inexpensive filler is used. When a certain calcium carbonate is used, there is a problem that carbon dioxide gas is generated due to decomposition and the white water system foams.

In order to solve the problems in acidic papermaking,
So-called neutral sizing agents have been developed which are suitable for papermaking in the neutral range without substantially using the sulfuric acid band. As the neutral sizing agent, various types using, for example, an alkyl- or alkenyl-substituted succinic anhydride, stearic anhydride, an alkyl ketene dimer, an alkyl ketene dimer derivative and the like are known.

By the way, a paper-making sizing agent is generally used by dispersing it in water, but an aqueous dispersion of a substituted succinic anhydride has a problem that it is inferior in physical stability and hydrolysis resistance. Various studies have been made to solve these problems. For example, in JP-A-62-156393, a substituted succinic anhydride is used as a copolymer of a polymerizable cationic surfactant, an aromatic vinyl monomer, a cationic vinyl monomer, and a water-soluble nonionic vinyl monomer. A method of dispersing a substituted succinic anhydride by using a polymer is disclosed in JP-A-6-101192, and an oil-in-water type surfactant and a cationic or amphoteric poly (meth) acrylamide are used. A method of improving the dispersion stability of the size by dispersing is disclosed.

[0005]

However, in the method disclosed in JP-A-6-101192, the content of the substituted succinic anhydride, which is an active ingredient, is essential because an oil-in-water type surfactant or the like is essential. However, there is a problem in that the size performance is inferior to that in the case where the surfactant is not mixed. Further, in the method disclosed in JP-A-62-156393, a polymerizable cationic surfactant or a nonionic vinyl monomer containing a hydroxyl group is used, so that the hydroxyl group is a substituted succinic anhydride. There was a problem that the reaction occurred and the dispersion system was adversely affected. Thus, the sizing agent prepared by the above method could not sufficiently improve both dispersion stability and sizing performance. An object of the present invention is to solve these problems, and further to provide a papermaking sizing agent in which a substituted cyclic dicarboxylic acid anhydride is dispersed without using an oil-in-water type surfactant or the like.

[0006]

[Means for Solving the Problems] To solve the above problems,
The present inventors focused their attention on a water-soluble polymer as a dispersant used when dispersing a substituted succinic anhydride in water, and conducted diligent studies, applying a water-soluble polymer as a dispersant, By introducing a (meth) acrylic acid alkyl ester monomer as a hydrophobic group and a hydrophilic monomer such as (meth) acrylamide into the composition of the water-soluble polymer, the water-soluble polymer can be made to have a surface-active effect to reduce its size. It was found that the substituted succinic anhydride can be stably dispersed in water without using an oil-in-water type surfactant which causes a performance deterioration. Furthermore, by using a hydrophobic monomer having a branched structure or a cyclic structure in the alkyl group of the hydrophobic (meth) acrylic acid alkyl ester monomers, the foamability of the sizing agent is reduced, and the amount of each monomer used falls within a specified range. It has been found that, by setting the above, it is possible to obtain a fine particle dispersion of a substituted succinic anhydride and further improve the dispersion stability of the obtained aqueous dispersion.

That is, the present invention polymerizes a substituted succinic anhydride (A), (1) a hydrophobic (meth) acrylic acid alkyl ester monomer, (2) a cationic monomer and (3) (meth) acrylamide. And a cationic (meth) acrylamide copolymer (B).

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION The papermaking sizing agent of the present invention comprises a substituted succinic anhydride (A) (hereinafter referred to as component (A)) and a cationic (meth) acrylamide copolymer (B).
(Hereinafter, referred to as component (B)).

The present invention will be described in detail below. As the component (A) used in the papermaking sizing agent of the present invention, various known ones can be used without particular limitation. For example, the general formula (I):

[0010]

[Chemical 1]

(In the formula, R ¹ represents an alkyl group or an alkenyl group having 9 to 23 carbon atoms), a substituted succinic anhydride having a linear or branched substituent, and

General formula (II):

[0013]

[Chemical 2]

(In the formula, R ² represents a linear or branched alkyl group having 1 to 27 carbon atoms, R ³ represents a linear or branched alkyl group or alkenyl group having 2 to 28 carbon atoms, And the total carbon number of R ² and R ³ is 9 to 29)
It is possible to use at least one selected from the group consisting of branched-chain substituted succinic anhydrides having a substituent represented by

The component (A) represented by the above general formula (I) is generally obtained by addition reaction of an α-olefin having a double bond at the terminal or an oligomer thereof with maleic anhydride. Various known products can be obtained as commercial products. Specific examples of the substituted succinic anhydride, octadecyl succinic anhydride, hexadecenyl succinic anhydride, heptadecenyl succinic anhydride, octadecenyl succinic anhydride, tetrapropenyl succinic anhydride. , Triisobutenyl succinic anhydride, 1
-Methyl-2-pentadecenyl succinic anhydride, 1-propyl-2-tridecenyl succinic anhydride, 1-ethyl-2-tetradecenyl succinic anhydride, 1-octyl-
Examples thereof include 2-decenyl succinic anhydride, polypropylenyl succinic anhydride, and polybutenyl succinic anhydride. It is also possible to use a saturated substituted succinic anhydride obtained by hydrogenating these unsaturated substituted succinic anhydrides.

Further, (A) represented by the above general formula (II)
The component is generally obtained by addition reaction of an internal olefin and maleic anhydride, but various known products can be obtained as commercial products. Specific examples of the branched chain substituted succinic anhydride include adducts of internal olefins such as decene-5, dodecene-6, tetradecene-7, hexadecene-7, octadecene.-9, eicosene-11 and maleic anhydride. And so on. Also,
Saturated substituted succinic anhydrides obtained by hydrogenating these unsaturated substituted succinic anhydrides can also be used.

The component (B) used in the present invention is (1) a hydrophobic (meth) acrylic acid alkyl ester monomer,
It is obtained by copolymerizing (2) a cationic monomer and (3) (meth) acrylamide.

(1) The hydrophobic (meth) acrylic acid alkyl ester monomers (hereinafter referred to as the component (1)) may be used without particular limitation as long as they are insoluble or hardly soluble in water. Specifically, for example, ethyl (meth) acrylate, propyl (meth) acrylate, normal butyl (meth) acrylate, lauryl (meth) acrylate, cetyl (meth) acrylate,
Stearyl (meth) acrylate and other alkyl groups having a linear structure, isobutyl (meth) acrylate, tertiary butyl (meth) acrylate and other branched alkyl groups, cyclohexyl (meth) acrylate, 2-ethylhexyl (meth) ) Acrylics, benzyl (meth) acrylates, isobornyl (meth) acrylates, and other cyclic structures. Among these (meth) acrylic acid alkyl ester monomers, those containing a branched structure and / or a cyclic structure are preferable because the resulting paper sizing agent will have good stability. When using a branched structure and / or a cyclic structure, 10 to 90 mol% of the hydrophobic (meth) acrylic acid alkyl ester monomer is used.
It is preferable to have a branched structure and / or a cyclic structure because it has an effect on the stability and low foaming property of the dispersion liquid. The alkyl group preferably has 4 to 18 carbon atoms. Above all, those having an alkyl group having 4 to 9 carbon atoms are particularly preferable because the hydrophobicity and hydrophilicity in the component (B) can be easily balanced and the component (A) can be dispersed very stably. . Specific examples include isobutyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, and cyclohexyl (meth) acrylate. In addition, although aromatic vinyl monomers such as styrene, vinyltoluene and α-methylstyrene, vinyl esters such as vinyl acetate and the like can be used in combination as a monomer for imparting hydrophobicity to the component (B),
Styrene, α-methylstyrene, etc. have poor copolymerizability with (meth) acrylamide and tend to be difficult to synthesize a stable water-soluble polymer, and it becomes impossible to sufficiently stabilize the dispersion of the component (A). Therefore, be careful when using it. Further, vinyl esters such as vinyl acetate are inferior in reactivity at the time of polymerization, and thus a large amount of unreacted monomer may remain, so that caution is required.

The amount of the component (1) used is not particularly limited, but is preferably about 0.5 to 20 mol%, particularly preferably 5 to 15 mol% based on the total molar sum of the monomers. . By using 0.5 mol% or more of the component (1), hydrophobicity is introduced into the component (B) so that it has a surface-active effect, and when the component (A) is dispersed, the dispersion particle diameter is very small. It is preferable because the product can be obtained.
On the other hand, when it exceeds 20 mol%, the hydrophobicity becomes too high and the aqueous solution of the component (B) tends to become cloudy, which makes it difficult to stabilize the dispersion of the component (A).

(2) Cationic monomer (hereinafter referred to as (2)
As the component), any vinyl monomer having a cationic group can be used without particular limitation.
Examples of the cationic monomer include dimethylaminoethyl (meth) acrylate, diethylaminoethyl (meth) acrylate, dimethylaminopropyl (meth) acrylamide, diethylaminopropyl (meth).
Examples thereof include vinyl monomers having a tertiary amino group such as acrylamide, salts thereof with inorganic or organic acids such as hydrochloric acid, sulfuric acid and acetic acid, or vinyl monomers containing a quaternary ammonium salt. The vinyl monomer containing a quaternary ammonium salt can be obtained, for example, by reacting the vinyl monomer containing a tertiary amino group with a quaternizing agent such as methyl chloride, benzyl chloride, dimethylsulfate, and epichlorohydrin. These cationic monomers may be used alone or in combination of two or more. Among these cationic monomers, benzyl chloride salts of dimethylaminopropyl (meth) acrylamide and diethylaminoethyl (meth) acrylate are preferable from the viewpoint of copolymerizability with other monomers of the component (B) and economical aspects. In addition, an anionic monomer such as (meth) acrylic acid may be used as long as the effect of the present invention is not impaired.

The amount of the component (2) used is not particularly limited, but it is preferably 0.5 to 30 mol%, and particularly preferably 5 to 25 mol% based on the total molar sum of the monomers. When component (2) is used in an amount of 0.5 mol% or more, hydrophilicity is introduced into component (B) so that it has a surface-active effect, and when component (A) is dispersed, a fine dispersion particle size is obtained. It is preferable because it is possible to impart the cationic property to the dispersed particles and the size performance is improved. Further, when the content is 30 mol% or less, hydrophilicity can be appropriately imparted to the component (B), and the dispersibility in water can be favorably maintained, which is preferable.

(3) (meth) acrylamide (hereinafter,
The term "(3) component" refers to acrylamide or methacrylamide, which can be used alone or in combination, but from the viewpoint of economy, it is preferable to use acrylamide alone.

The amount of the component (3) used is not particularly limited, but is preferably 50 to 99 mol%, and particularly preferably 60 to 90 mol% based on the total molar sum of the monomers. It is preferable to keep the amount of the component (3) used within the above range because the component (1) and the component (2), that is, hydrophobicity and hydrophilicity can be introduced into the component (B) in good balance. Outside the above range, when the component (A) is dispersed, it is difficult for the dispersed particle size to be small, and the dispersion stability tends to decrease, so the size performance may deteriorate.

The component (B) can be obtained by copolymerizing the mixture of the components (1) to (3) in a solvent in the presence of a radical initiator. For the copolymerization, a known polymerization method can be adopted. Examples of the solvent to be used include organic solvents such as ethyl alcohol, isopropyl alcohol, tertiary butyl alcohol, dioxane and water, and these can be used alone or in combination of two or more.
As the radical initiator, a persulfate such as potassium persulfate or ammonium persulfate, or a redox-based polymerization initiator in the form of a combination thereof with a reducing agent such as sodium bisulfite or 2,2′-azobis (2-amidino) is used. Propane) dihydrochloride, 2,2′-azobisisobutylnitrile, 2,2′-azobis (2,4-dimethylvaleronitrile) and other azo initiators, and benzoyl peroxide and other peroxides. However, these may be selected and used according to the solvent used. A known water-soluble chain transfer agent such as isopropyl alcohol or mercaptoethanol may be used to adjust the molecular weight. Polymerization is performed by adding a mixture of components (1) to (3), a solvent, an initiator and a chain transfer agent, and then stirring the mixture.
By heating, the desired cationic (meth) acrylamide copolymer can be obtained.

The thus-obtained cationic (meth) acrylamide copolymer has a Brookfield viscosity at 25 ° C. (hereinafter referred to as viscosity) of 30% by weight of solid content.
Is usually about 500 to 100,000 mPa · s, preferably 1,000 to 20,000 mPa · s, and similarly the pH of the aqueous solution is about 2.0 to 7.0, preferably 3.0. Is about 6.0.

The amount of the component (B) used in the present invention is not particularly limited, but usually 5% by weight of the component (B) relative to the component (A) (solid content of the cationic water-soluble copolymer). Or more), preferably 10% by weight or more. (B)
There is no particular upper limit to the amount of the component used, but the solid content is usually 50% by weight or less, preferably 30% by weight or less. When the amount of the component (B) used is lower than 5% by weight,
The water dispersibility of the component (A) tends to decrease.

The papermaking sizing agent of the present invention is obtained by dispersing the component (A) in water with the component (B) without using an oil-in-water type surfactant. As a method of dispersing the component (A) in water, a conventionally known method can be adopted. For example, it can be produced by a known method such as a forced emulsification method, an inversion emulsification method, or a high pressure emulsification method after mixing the components (A) and (B). That is, in the case of the forced emulsification method, a mixture of the component (A) and the component (B) forming the dispersed phase and sufficient water as a dispersion medium is forcibly emulsified and dispersed by mechanical shearing such as a high speed homomixer. By this, the aqueous dispersion can be obtained, and in the case of the inversion emulsification method, after sufficiently kneading the mixture of the component (A) and the component (B) forming the dispersed phase, water is added with stirring. By inversion of the phase, the aqueous dispersion can be obtained. Among these, the inversion emulsification method is preferable because the obtained aqueous dispersion has fine and uniform dispersed particle diameters and the dispersion stability is improved.

The non-volatile concentration of the aqueous dispersion obtained by the above method is not particularly limited and may be arbitrarily determined.
Usually, it is adjusted to about 0.1 to 30% by weight. The average particle size of the obtained dispersed particles is about 0.1 to 2 μm, but considering the size performance and dispersion stability of the aqueous dispersion, an emulsification method capable of adjusting the average particle size to 0.3 to 1 μm. It is preferable to select the emulsification conditions. The aqueous dispersion thus obtained can be used after further dilution if necessary. The aqueous dispersion has a milky white appearance and usually has a pH of about 2.0 to 7.0. Also,
The aqueous dispersion is stable at room temperature (5 to 30 ° C.) and does not cause precipitation or flotation.

Next, a sizing method using the aqueous dispersion will be described. As a method of internal addition sizing, the aqueous dispersion may be continuously and quantitatively added to a pulp slurry as shown below through various known quantitative pumps or the like for sizing. The pulp slurry is not particularly limited, kraft pulp, bleached or unbleached chemical pulp such as sulfite pulp, groundwood pulp, mechanical pulp, bleached or unbleached high-yield pulp such as thermomechanical pulp, waste newspaper, It is possible to use waste paper pulp such as waste magazine paper, corrugated cardboard waste paper, and deinked waste paper. Furthermore, during papermaking, fillers, dyes, dry paper strength improvers,
Internal additives such as a wet paper strength improver and a yield improver can also be used. Since the dispersed particles of the aqueous dispersion have a cationic property, they can be self-fixed to anionic pulp fibers and exhibit a size effect. For this reason, it is preferable to use it under papermaking conditions in the weakly acidic to neutral range where cationic chemicals such as cation-modified starch and size fixing agent are not used. The amount of the aqueous dispersion used is not particularly limited, but usually the substituted succinic anhydride is about 0.01 to 2.0% by weight, preferably 0.05 to 1 in terms of solid content, based on the weight of the cellulose fiber. It is 0.0% by weight.

There are no particular restrictions on the means for sizing the surface of the paper using the aqueous dispersion, and various means can be adopted. For example, it is applied with a size press, a gate roll coater, a bill blade, a calendar or the like. The amount of the aqueous dispersion used is not particularly limited, but usually substituted succinic anhydride is about 0.002 to 1.0 g, preferably 0.005 to 1 m ^{2 of the} coated base paper. It may be applied to the surface of the base paper so that the amount becomes about 0.4 g. The type of base paper to be surface sized is not particularly limited, and paper using ordinary pulp raw materials, that is, bleached or unbleached chemical pulp such as kraft pulp, sulfite pulp, groundwood pulp, mechanical pulp, thermomechanical pulp, etc. It is possible to use any paper using waste paper pulp such as bleached or unbleached high-yield pulp, newspaper waste paper, magazine waste paper, cardboard waste paper, and deinked waste paper.

[0031]

The papermaking sizing agent of the present invention is an aqueous dispersion of a substituted succinic anhydride having good dispersion stability, and also has good emulsification dispersibility of the substituted succinic anhydride. Further, since the sizing agent of the present invention does not use an oil-in-water type surfactant or the like, it has good sizing performance and less foaming as compared with the conventional substituted succinic anhydride sizing agent. Further, since the dispersed particles of the aqueous dispersion are cationic, sufficient size performance can be expected without using them even in a papermaking system in which a cationic fixing agent or the like is conventionally used together.

[0032]

The present invention will be described in more detail below with reference to examples and comparative examples, but the present invention is not limited to these examples. In the examples, all parts and% are by weight unless otherwise specified.

(Synthesis of Water-Soluble Polymer) Production Example 1 74.0 g of 100% acrylamide and 258 g of water were added to a 1000 ml four-necked Korben equipped with a stirrer, a thermometer, a reflux condenser and a nitrogen gas inlet tube. After dissolving well, 100% dimethylaminopropyl acrylamide 2
8.0 g and 32 g of benzyl chloride salt of 75% dimethylaminoethyl methacrylate were added, and the pH was adjusted to 3.5 to 4.5 with a 50% sulfuric acid aqueous solution. Next, 140.0 g of isopropyl alcohol and 25 g of isobutyl methacrylate were added, and then oxygen in the reaction system was removed with nitrogen gas. Then, the temperature was raised to 50 ° C. with stirring, and 30.3 g of a 1% ammonium persulfate aqueous solution was added, and then 80
The temperature was raised to 40 ° C. over 40 minutes, and the temperature was kept at the same temperature for 3 hours. After completion of the reaction, isopropyl alcohol was distilled off, and then the concentration was adjusted to obtain a cationic water-soluble copolymer having a solid content of 30.3%. The water-soluble copolymer had a viscosity at 25 ° C. of 3,600 mPa · s and a pH of 3.9.

Production Examples 2 to 6 and Comparative Production Examples 1 to 3 Various cationic aqueous solutions were prepared in the same manner as in Example 1 except that the constituent monomer components and the mol% charged were changed as shown in Table 1. A sex copolymer was obtained. The physical properties (nonvolatile matter, viscosity at 25 ° C. and pH) of the obtained water-soluble copolymer are shown in Table 1.

[0035]

[Table 1] The abbreviations of the monomers used in the table are as follows. MMA: methyl methacrylate iBMA: isobutyl methacrylate nBMA: normal butyl methacrylate 2EHA: 2-ethylhexyl acrylate CHMA: cyclohexyl methacrylate LMA: lauryl methacrylate APDM: dimethylaminopropylacrylamide DMAEABz: benzyl chloride salt of dimethylaminoethyl acrylate AA: acrylic acid

(Preparation of Aqueous Dispersion) Example 1 100 parts by weight of substituted succinic anhydride was added to 500 ml Kolben equipped with a stirrer, and 10 parts by weight of the cationic water-soluble copolymer obtained in Production Example 1 was added. , And 15.6 parts by weight of water, and then kneading for 3 minutes under stirring at 400 rpm, and then 19850 parts by weight of water were gradually added to invert the phase to obtain 0.5% concentration of the substituted succinic anhydride. An aqueous dispersion was prepared. Table 2 shows the preparation method, the substituted succinic anhydride used, and the blending amount.

Example 2 In a 1000 ml stainless steel cup, 10 parts by weight of the water-soluble copolymer obtained in Production Example 1 as a solid content and 1986 as water.
After adding 7.0 parts by weight and stirring well, 100 parts by weight of substituted succinic anhydride was added, and the mixture liquid of the components was homomixer (manufactured by Tokushu Kika Kogyo Co., Ltd .; TK homomixer MII type).
A 0.5% strength aqueous dispersion of the substituted succinic anhydride was prepared by applying a shear force of 10,000 rpm for 2 minutes. Table 2 shows the preparation method, the substituted succinic anhydride used, and the blending amount.

Examples 3 to 11, Comparative Examples 1 to 4 In addition to changing the compounding amounts of the cationic water-soluble copolymers produced in Production Examples 1 to 6 and Comparative Production Examples 1 to 3, as shown in Table 2. In the case of the inversion emulsification method, the same operation as in Example 1 and in the case of the forced emulsification method were carried out to prepare a 0.5% concentration aqueous dispersion of substituted succinic anhydride. In addition,
The preparation method, the substituted succinic anhydride used, and the blending amount are summarized in Table 2.

[0039]

[Table 2]

(Measurement of Surface Potential (Zeta Potential) of Dispersed Particles) 0.01% of the substituted succinic anhydride of each aqueous dispersion immediately after preparation obtained in Examples 1 to 11 and Comparative Examples 1 to 4 was used. After diluting to a concentrated aqueous solution, the surface potential of the dispersed particles was measured with a zeta potential meter (Lazer-Zee-Model 501; manufactured by PENKEM). The results are shown in Table 3.

(Measurement of Average Particle Size of Dispersed Particles) Examples 1 to 1
11, the average particle diameter immediately after the preparation of the aqueous dispersions obtained in Comparative Examples 1 to 4 and after standing for 3 hours at room temperature was measured by a laser diffraction particle size distribution analyzer (SALD200
0: measured using Shimadzu Corporation. The results are shown in Table 3. In addition, when the measurement by the device is difficult due to the increase of the particle size over time, the measurement is not possible.

(Evaluation of Performance of Aqueous Dispersion) Examples 1 to 1
1. Size performance evaluation was performed on each of the various aqueous dispersions obtained in Comparative Examples 1 to 4. The results are summarized in Table 3.

(Papermaking conditions) Pulp: Waste cardboard (Canadian Standard Paper
Reness 285 ml) Alum: Aluminum sulfate, 14-18 hydrate (Wako
Made by Junyaku Kogyo Co., Ltd. Yield improver: Cationic polyacrylamide polymer
(Percoll 47, Kyowa Sangyo Co., Ltd.) Solid content: Alum (2.0% by weight of pulp), sizing agent
(Vs pulp weight 0.15%), retention aid (vs pulp weight
Amount 0.005%) Order of addition: pulp-Alum-size-retention improver PH during paper making: 6.8 ± 0.1 Papermaking: Tappy Maru Small Handmade Machine (Kumagaya Riki Kogyo Co., Ltd.)
Made) Press: 3.5kgW / cm^Two× 2 minutes Drying: rotary dryer, 100 ° C x 1 minute Weighing: 62.0 ± 0.5 g / m^Two Tightness: 0.50 ± 0.1 g / cm³

(Paper quality evaluation) Basis weight: According to JIS P 8124. Tightness: According to JIS P 8118.

(Performance Evaluation) Steckigt Sizing Degree: According to JIS P 8122.

(Evaluation of Performance of Aqueous Dispersion) (Foamability Test) The various aqueous dispersions obtained in Examples 1 to 11 and Comparative Examples 1 to 4 were evaluated for foamability by simulating a papermaking system. 500 g of a 0.5% strength pulp slurry containing chemicals was transferred to a 1000 ml graduated cylinder, and air bubbling was carried out using a glass ball filter to force foaming. The liquid level height before the test was subtracted from the maximum foam height during the test to obtain the foaming amount (ml). The results are summarized in Table 3. (Expansion test conditions) Pulp: Corrugated cardboard waste paper (Canadian Standard Freeness 285 ml) Alum: Aluminum sulfate 14-18 hydrate (manufactured by Wako Pure Chemical Industries, Ltd.) Yield improver: Cationic polyacrylamide polymer (Percoll 47, manufactured by Kyowa Sangyo Co., Ltd.) Solid content: Alum (2.0% by weight of pulp), sizing agent (1.5% by weight of pulp), retention aid (0.005% by weight of pulp) Order of addition: pulp-Alum-size-retention improver pH during test: 6.8 ± 0.1

[0047]

[Table 3]

Evaluation Examples 1 to 11 in Table 3 and Comparative Evaluation Example 1
From 4, the dispersed particles in each of the papermaking sizing agents of the present invention are cationic and exhibit excellent sizing performance.
Little foaming in pulp slurry simulating papermaking system.
Further, by using the component (B), fine dispersed particles can be obtained, and they have good dispersion stability over time.

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Yohei Otsuka             Arakawa, 3-4-3 Imafuku Minami, Joto-ku, Osaka             Gaku Kogyo Co., Ltd. F term (reference) 4L055 AG41 AG71 AG73 AH12 AH33                       EA30 EA32 FA23 FA30

Claims (5)

[Claims] 1. A cationic polymer obtained by polymerizing a substituted succinic anhydride (A), (1) a hydrophobic (meth) acrylic acid alkyl ester monomer, (2) a cationic monomer and (3) (meth) acrylamide. A papermaking sizing agent containing a (meth) acrylamide copolymer (B). 2. The cationic (meth) acrylamide copolymer (B) comprises (1) 0.5 to 20 mol% of a hydrophobic (meth) acrylic acid alkyl ester monomer, and (2) a cationic monomer of 0.5 to 30 mol% and (3) (meta)
The paper sizing agent according to claim 1, which is a copolymer of 50 to 99 mol% acrylamide. 3. The papermaking sizing agent according to claim 1, wherein the alkyl group of the hydrophobic (meth) acrylic acid alkyl ester monomer is at least one selected from the group consisting of a branched structure and a cyclic structure. 4. (1) The alkyl group of the hydrophobic (meth) acrylic acid alkyl ester monomer has 4 to 18 carbon atoms.
The papermaking size according to any one of claims 1 to 3. 5. The cationic monomer is selected from the group consisting of a vinyl compound having a tertiary amino group, a salt of a vinyl compound having a tertiary amino group and a vinyl compound having a quaternary ammonium salt. The papermaking sizing agent according to claim 1, which is at least one kind.