JPH10204792A - Surface sizing agent - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a surface sizing agent capable of imparting an excellent sizing degree, barrier properties and oil resistance to a paper and useful as a writing paper, a packaging paper, etc., for foods by using a mixed ion complex substance consisting essentially of an anionic sizing agent and a specific acrylamide-based polymer as an active component. SOLUTION: This surface sizing agent comprises a mixed ion complex substance consisting essentially of (A) an anionic sizing agent and (B) an acrylamide-based polymer having a cationic group and/or an amphoteric group preferably at (20:80) to (95:5) weight ratio of the components A:B as an active component. When a paper is coated with the surface sizing agent in various size pressing steps, gate roll coating or calender coating, etc., even antislip properties of the paper can be improved.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is used in various size pressing processes in papermaking processes, gate roll coating or calender coating, etc., to impart an excellent strong size effect to paper, and at the same time, to provide a barrier property, The present invention relates to a surface sizing agent that can significantly improve oil resistance, slip resistance, and the like.

[0002]

2. Description of the Related Art Conventionally, anionic polymers such as styrene-maleic acid polymer, styrene- (meth) acrylic polymer, styrene- (meth) acrylic acid polymer, and olefin polymer have been used as surface sizing agents.
Cationic polymers are known. For example, JP
JP-A-9-71205 discloses a salt of a copolymer containing styrene and maleic anhydride, maleic acid and / or a half ester thereof as essential monomers. JP-A-499-1
No. 02906 discloses a copolymer in the form of a salt composed of a half ester of an αβ-monoolefin type unsaturated dicarboxylic acid, (meth) acrylic acid and a monovinyl aromatic compound. JP-A-56-63098 discloses an alkali metal salt, ammonium salt or amine salt of a polymer containing methacrylic acid and a styrene monomer as essential components. JP-A-62-184194 discloses that
A method using a styrene unit, an acrylate monomer and maleic acid (anhydride) as constituent units is disclosed.
JP-A-60-146098 discloses a water-soluble polymer composed of an αβ-unsaturated polycarboxylic acid partial half ester, an αβ-unsaturated polycarboxylic acid (salt) and an α-olefin. JP-A-2-26997 discloses styrene and / or a styrene derivative and N.P. It is described that a reaction product obtained by reacting a copolymer containing N-dialkylaminoalkyl (meth) acrylamide with a quaternizing agent is effective as a size effect and an anti-slip agent. Japanese Patent Application Laid-Open No. 8-158292 discloses surface strength, water resistance, ink resistance, sizing property and the like composed of a copolymer of an acrylamide polymer having an anionic group, a hydrophobic vinyl monomer and an anionic vinyl monomer. A surface paper quality improver for improving printability of paper is disclosed.
JP-A-55-40820 discloses a writing paper with improved oil resistance.

[0005]

Recently, due to environmental problems, paper raw materials have been increased due to an increase in the mixing ratio of recycled paper, closed paper machines due to drainage regulations, and speeding up of paper machines to improve productivity. Is becoming less effective. Further, as the weight of the paper is reduced, the printing speed is increased, and the offset is advanced, the printing conditions are becoming more and more severe. In particular, there is a strong demand for paper having a strong size corresponding to dampening water in offset printing. In order to respond to these demands, chemicals are internally added to pulp slurry or externally added (coated on the surface of paper). Of these, the internal additive has poor yield, and if a large amount of sizing agent is used, the machine will become dirty,
Problems such as foaming have occurred. External addition is known to be advantageous because the yield is almost 100% and adheres directly to paper, and surface sizing agents are often used. However, conventional surface sizing agents are often used alone, but their size effect is still unsatisfactory. If the surface sizing agent is applied at a high concentration, a material close to a strong size can be obtained, but foaming troubles in the actual operation, dirt of the dryer, etc. occur, and it is not practical, and furthermore, it cannot withstand cost. . The development of a sizing agent for high-size paper at a practical level is eagerly desired.

[0006] When writing with an oil-based marking pen, the writing paper has a problem that the oil-based ink permeates to the back side. To solve this, it is necessary to improve the oil resistance of the paper. The purpose of food packaging paper is to protect the contents. For example, paper having barrier properties and oil resistance is desired in order to prevent food from deteriorating due to oxygen, to isolate it from odors, and to prevent contamination from the contents of the package. That is, the present invention provides a surface sizing agent which imparts barrier properties and oil resistance to paper at the same time as excellent strength.

[0007]

Means for Solving the Problems The present inventors have conducted intensive studies in order to solve the above-mentioned problems, and as a result, have found that an anionic sizing agent (A) and an acrylamide having a cationic group and / or a zwitterionic group. An excellent sizing effect is exhibited by applying the surface sizing agent of the present invention comprising a mixed ion complex of the (A) component and the (B) component as a main component to the paper, comprising the main polymer (B) as a main component. At the same time, the barrier property, the oil resistance, and the slip resistance of the paper are greatly improved. The reason for this is not clear, but it is thought that the ion complex of the present invention may be concentrated on the surface of paper, in particular, to fix it, and to promote the orientation of the hydrophobic groups of the surface sizing agent. Can be

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in more detail. As the anionic sizing agent (A) of the present invention, various sizing agents from a water-soluble polymer type to an emulsion type can be used, and preferably, a styrene-maleic acid-based copolymer salt, styrene- (meth) acrylic acid Copolymer salt, styrene- (meth) acrylate- (meth)
Aqueous solutions such as acrylic acid copolymer salts, olefin-maleic anhydride copolymers and derivatives thereof such as partial esters or partial amides, and vinyl acetate-maleic acid-based copolymer salts.

Unless the effects of the present invention are impaired, other component monomers such as styrene derivatives such as α-methylstyrene, vinyl acetate, vinyl chloride, vinylidene chloride, acrylamide and derivatives thereof, vinylpyrrolidone, allyl No copolymerization of alcohol, hydroxy group-containing (meth) acrylic esters, polyoxyalkylene (meth) acrylates, glycidyl (meth) acrylate, sulfone group-containing monomers, acrylonitrile, and other various monomers No problem.

Further, the anionic sizing agent (A) of the present invention will be described in detail. A styrene-maleic acid copolymer salt is a copolymer salt of styrene and maleic anhydride or a copolymer of styrene and maleic ester. It is a polymer salt.
The maleic acid ester is composed of maleic anhydride and 1 to 1 carbon atoms.
It is a half ester composed of 30 linear or branched alkyl alcohols or alkylphenyl alcohols, and can be used alone or in combination depending on the required physical properties. The composition ratio when copolymerizing styrene with maleic anhydride or maleic acid half-ester is often in equimolar amounts, but any one of them may be large. The styrene- (meth) acrylic acid copolymer salt is obtained by copolymerizing styrene with acrylic acid, styrene with methacrylic acid, styrene with acrylic acid, and methacrylic acid. The composition ratio of the styrene and (meth) acrylic acid is 30 to 90 mol% of styrene.
And (meth) acrylic acid 10 to 70 mol%, preferably,
Styrene 40-60 mol% and (meth) acrylic acid 40-
60 mol%.

The styrene- (meth) acrylic acid ester- (meth) acrylic acid copolymer salt is a copolymer of styrene, (meth) acrylic acid ester and (meth) acrylic acid to form a copolymer. obtain. The composition ratio is styrene 0
２０20 mol%, (meth) acrylate 30-90
Mol%, and 10 to 70 mol% of (meth) acrylic acid are preferred. The olefin-maleic anhydride copolymer preferably has a composition ratio of ethylene, diisobutylene, α-olefins of 40 to 60 mol% and maleic anhydride of 40 to 60 mol%. Of course, partial alcohol esters or partial amides of this copolymer may also be used.

The anionic sizing agent of the present invention is prepared by a polymerization method such as a bulk polymerization method, a solution polymerization method, and an emulsion polymerization method, but is not limited thereto. A copolymer can be easily obtained by performing solution polymerization. Examples of the polymerization catalyst include a peroxide such as benzoyl peroxide and an azo compound such as azopisisobutyrone tolyl. The copolymer obtained after the polymerization is alkali metal such as caustic soda, caustic potash, ammonium, alkylamines, alkanolamines, morpholines, neutralized with alkaline water such as polyamines such as ethylenediamine to form a salt, An aqueous solution of an anionic sizing agent is obtained. These alkalis may be used alone or in combination, and the degree of neutralization is 50 to 120 mol%, preferably 90 to 110 mol%.

The molecular weight of the anionic sizing agent of the present invention is about 2,000 to 200,000, preferably 5,000.
0 to 100,000. If the molecular weight is low, a sufficient size effect cannot be obtained. If the molecular weight exceeds 200,000, the viscosity increases and the workability deteriorates.

A water-soluble solvent such as alcohols, glycols and cellosolves may be added to the aqueous solution of the anionic sizing agent of the present invention, if necessary, for the purpose of improving viscosity stability and volatility.

The acrylamide-based polymer having a cationic group and / or a zwitterionic group of the present invention contains (meth) acrylamide as a main monomer component and has a cationic group and / or a zwitterionic group. Polymer. This compound modifies a water-soluble polymer containing (meth) acrylamide as a main component, or a vinyl monomer mixture of (meth) acrylamide and a cationic vinyl monomer or (meth) acrylamide and a cationic vinyl monomer and an anionic vinyl monomer. Is prepared by a method of copolymerizing Regardless of which method is used, the acrylamide-based polymer having a cationic group and / or a zwitterionic group used in the present invention contains 65 to 99 mol% of (meth) acrylamide and 1 to 20 mol% of a cationic group. 0 to 15 mol% of anionic group
Desirably, it is 80 to 99 mol% of (meth) acrylamide, 0 to 10 mol% of anionic group, and 1 to 10 mol% of cationic group.

The acrylamide-based polymer (B) having a cationic group and / or a zwitterionic group is converted to a (meth)
When preparing a water-soluble polymer having acrylamide as a main component by modification, cationic introduction is performed by alkylaminomethylated polyacrylamide by Mannich reaction, aminated polyacrylamide by Hoffman reaction, or transamidation reaction by polyamine, For the introduction of the anionic group, an alkali hydrolysis reaction of an amide group or a sulfomethylation reaction is used.

When an acrylamide polymer (B) having a cationic group and / or a zwitterionic group is prepared by a copolymerization method, the cationic vinyl monomer component usable as a vinyl monomer component may be a compound represented by the general formula (I) As monomers shown in 1), dimethylaminoethyl (meth)
Acrylate, diethylaminoethyl (meth) acrylate, dimethylaminopropyl (meth) acrylate,
And diethylaminopropyl (meth) acrylate. As the general formula (2), dimethylaminopropyl (meth) acrylamide, diethylaminopropyl (meth)
Acrylamide, etc.], and other cationic monomers include vinyl monomers having a tertiary amino group such as vinylpyridine, vinylimidazole, arylamine, and diarylamine, and inorganic monomers such as hydrochloric acid, sulfuric acid, formic acid, and acetic acid. Acids or salts of organic acids,
Or a vinyl monomer containing the tertiary amino group and an alkyl halide such as methyl chloride and methyl bromide;
A quaternary agent obtained by a reaction with a quaternizing agent such as an arylalkyl halide such as benzyl chloride or benzyl bromide, dimethyl sulfate, diethyl sulfate, epichlorohydrin, 3-chloro-2-hydroxypropyltrimethylammonium chloride or glycidyltrialkylammonium chloride. Grade ammonium salts and the like can be used, and one kind of these vinyl monomer components can be used alone or in combination of two or more kinds.

[0018]

Embedded image

When an acrylamide polymer (B) having a cationic group and / or a zwitterionic group is prepared by a copolymerization method, methacrylic acid, acrylic acid, , Maleic acid, fumaric acid, αβ-
Examples include unsaturated carboxylic acids, vinyl monomers having a sulfonic acid group or a phosphoric acid group, and alkali metal salts or ammonium salts of these various sodium and potassium salts. One of these vinyl monomer components may be used alone, or two or more thereof may be used in combination.

The acrylamide-based polymer (B) having a cationic group and / or a zwitterionic group of the present invention can be copolymerized with (meth) acrylamide or the above-mentioned cationic vinyl monomer or anionic vinyl monomer. The vinyl monomer can be contained within a range not exceeding 20 mol%. This type of vinyl monomer includes, for example, various crosslinkable vinyl monomers such as methylol (meth) acrylamide, dimethylacrylamide, bifunctional, trifunctional, and tetrafunctional, as well as diisopropylacrylamide, styrene, allyl alcohol, (meth) Examples include acrylates, acrylonitrile, vinyl acetate, hydroxyl group-containing (meth) acrylates, and vinylpyrrolidone.

The preparation of the acrylamide polymer having a cationic group and / or a zwitterionic group of the present invention can be carried out by various methods known in the art. For example, (meth) acrylamide, a vinyl monomer component, and water are charged into a container equipped with a predetermined stirrer and a nitrogen gas introduction pipe so that the total vinyl monomer concentration becomes 5 to 30% by weight, preferably 10 to 20% by weight. A redox initiator obtained by combining a peroxide such as hydrogen peroxide, ammonium persulfate, potassium persulfate, or ammonium hydroperoxide, or a combination thereof with a reducing agent such as bisulfite, or Polymerization is carried out by adding a water-soluble azo-based polymerization initiator such as 2-2 'azohis (2-aminodipropane) hydrochloride. If necessary, a polymerization adjuster such as isopropyl alcohol, allyl alcohol, sodium hypophosphite, mercaptoethanol, thioglycolic acid, or a chain transfer agent can be appropriately used.

The molecular weight of the resulting acrylamide-based polymer having a cationic group and / or a zwitterionic group may range from 10,000 to 3,000, 000 if importance is placed on barrier properties.
0, preferably 50,000 to 1,000,000. If the molecular weight is 10,000 or less, barrier properties and size effects are poor. If the molecular weight is 3,000,000 or more, workability is problematic and handling is difficult. Becomes

The weight ratio of the anionic sizing agent (A) of the present invention to the acrylamide polymer (B) having a cationic group and / or a zwitterionic group is (A) :( B) =
20-80: 95-5 is preferred.

The mixed ionic complex of the anionic sizing agent (A) and the acrylamide polymer having a cationic group and / or a zwitterionic group can be obtained by mixing p
Since the balance changes depending on H, the pH may be adjusted with an organic acid, an inorganic acid, or an alkali to an appropriate pH that does not precipitate depending on the mixing ratio and ion ratio of the two.

The coating density of the surface sizing agent of the present invention is determined by the amount of liquid absorbed (adhered amount) to the base paper for coating and the target sizing degree required for the paper. %. When emphasis is placed on barrier properties and oil resistance rather than size properties, it is needless to say that the barrier properties and oil resistance are not limited to these, and the higher the coating density, the higher the density.

The coating amount on the paper of the present invention may be lower than that of the conventional surface sizing agent in order to give the surface sizing agent of the present invention an excellent sizing effect.
g / m ² (pure content): preferably 0.005 to 1 g / m ²
It is.

The paper coated with the surface sizing agent of the present invention can exhibit sizing properties by drying at room temperature.
By heating and drying at 50 to 130 ° C., a better size effect is exhibited.

The size coating solution containing the surface sizing agent of the present invention is applied to the surface of the paper by various coating equipment such as a size press, a gate roll, a calender, and an air knife. You can also.

The essential component of the surface sizing agent of the present invention is a mixed ion complex of an anionic sizing agent (A) and an acrylamide polymer (B) having a cationic group and / or a zwitterionic group. However, as long as the effects of these components are not impaired, other compounding agents such as starch derivatives, water-soluble cellulose derivatives, polyvinyl alcohol, vegetable gums, alginates, acrylamide polymers and the like are appropriately compounded as necessary. It goes without saying that you can do it.

The base paper to which the surface sizing agent of the present invention is applied is as follows:
It is not particularly limited, and is not limited to pulp, filler, internal sizing agent, paper strength enhancer, retention agent, and the like. Further, it can be used in any neutral to acidic papermaking. For example, high quality paper, medium paper, newsprint, coated base paper, special paper, processed base paper, liner, white board, PPC paper, inkjet,
Alternatively, the present invention can be applied to toner printer paper, information paper such as thermal paper, and gypsum board base paper.

[0031]

EXAMPLES Hereinafter, the present invention will be described in more detail based on examples, comparative examples, and applied examples, but the present invention is not limited to these examples.

Example 1 50 parts by weight of styrene and 50 parts by weight of methacrylic acid are subjected to solution polymerization under reflux using azobisisobutyronitrile (AIBN) as an initiator in the presence of an isopropyl alcohol solvent. After the polymerization, a predetermined aqueous ammonia is added to neutralize.
After that, the solvent was removed by distillation under reduced pressure, predetermined water was added,
An anionic sizing agent A-1 having a viscosity of 80 cps / 25 ° C., a solid content of 15%, and a pH of 9.0 was obtained. Next, 80 parts by weight of acrylamide and N.I. 26 parts by weight of N-dimethylaminopropylacrylamide and 8 parts by weight of acrylic acid are polymerized in an aqueous solution using a redox catalyst of ammonium persulfate and sodium bisulfite, and the viscosity is 11,000 cps / 25.
Thus, an amphoteric acrylamide polymer B-1 having a solid content of 10 ° C., a solid content of 10% and a pH of 4.0 was obtained. These aqueous solutions were mixed to obtain a surface sizing agent. The properties are shown in Table 1.

Example 2.3.4 The blending ratio of the surface sizing agent A-1 of Example 1 to the zwitterionic acrylamide polymer B-1 was expressed as A in terms of solids weight ratio.
-1: B-1 = 70: 30, 50:50, 25:75 to obtain a surface sizing agent. The properties are shown in Table 1.

Example 5 80 parts by weight of acrylamide and N.P. 13 parts by weight of N-dimethylaminopropylacrylamide and 2.4 parts by weight of itaconic acid are polymerized in an aqueous solution using a redox catalyst of ammonium persulfate and sodium bisulfite, and have a viscosity of 9600 cp.
Thus, an amphoteric acrylamide polymer B-2 having an s / 25 ° C., a solid content of 10%, and a pH of 4.1 was obtained. An aqueous solution of the anionic sizing agent A-1 of Example 1 and the amphoteric acrylamide-based polymer B-2 was used in terms of solid content weight ratio of A-1: B-
2 = 50: 50 to obtain a surface sizing agent. The properties are shown in Table 1.

Example 6 70 parts by weight of styrene and 30 parts by weight of acrylic acid are subjected to solution polymerization under reflux using azobisisobutyronitrile (AIBN) in the presence of isopropyl alcohol. After the polymerization, the mixture is neutralized by adding a predetermined aqueous ammonia. Thereafter, the solvent was removed by distillation under reduced pressure, predetermined water was added, and
An anionic sizing agent A-2 having 00 cps / 25 ° C., a solid content of 15%, and a pH of 9.0 was obtained. The anionic sizing agent A-2 was prepared by mixing the aqueous solution of the zwitterionic acrylamide-based polymer B-1 of Example 1 with a solid content weight ratio of A-2: B-1 = 5.
The mixture was mixed at 0:50 to obtain a surface sizing agent. The properties are shown in Table 1.

Example 7 80 parts by weight of acrylamide and N.P. 27 parts by weight of N-dimethylaminoethyl methacrylate and 8 parts by weight of acrylic acid are polymerized in an aqueous solution using a redox catalyst of ammonium persulfate and sodium bisulfite, and have a viscosity of 12100 cp.
Thus, an amphoteric acrylamide polymer B-3 having an s / 25 ° C., a solid content of 10%, and a pH of 3.9 was obtained. An aqueous solution of the anionic sizing agent A-1 of Example 1 and the amphoteric acrylamide-based polymer B-3 was used at a solid content weight ratio of A-1: B-3.
= 50: 50 to obtain a surface sizing agent. The properties are shown in Table 1.

Example 8 80 parts by weight of acrylamide and N.P. 14 parts by weight of N-dimethylaminopropylacrylamide, 8 parts by weight of acrylic acid, and 1 part by weight of methylenebisacrylamide are polymerized in an aqueous solution using a redox catalyst of ammonium persulfate and sodium bisulfite, and the viscosity is 8600 cps / 25 ° C., solid content A zwitterionic acrylamide polymer B-4 having a pH of 15% and a pH of 4.1 was obtained. Anionic sizing agent A of Example 1
1 and an aqueous solution of zwitterionic acrylamide polymer B-4 were mixed at a solid content ratio of A-1: B-4 = 50: 50 to obtain a surface sizing agent. The properties are shown in Table 1.

Example 9 80 parts by weight of acrylamide and N.P. 24.4 parts by weight of N-dimethylaminoethyl methacrylate was polymerized in an aqueous solution using a redox catalyst of ammonium persulfate and sodium bisulfite, and the viscosity was 9000 cps / 25 ° C., solid content 1
0%, pH 4.0, of a cationic acrylamide-based polymer B-5 was obtained. Anionic sizing agent A-1 of Example 1
And an aqueous solution of the cationic acrylamide-based polymer B-5 were mixed at a solid content weight ratio of A-1: B-5 = 50: 50 to obtain a surface sizing agent. The properties are shown in Table 1.

Comparative Example 1 80 parts by weight of acrylamide and 8.1 parts by weight of acrylic acid were polymerized in an aqueous solution using a redox catalyst of ammonium persulfate and sodium bisulfite to give a viscosity of 12,000 cps /
An anionic acrylamide polymer C-1 having a solid content of 25 ° C., a solid content of 15% and a pH of 7.0 was obtained. An aqueous solution of the anionic sizing agent A-1 of Example 1 and the anionic acrylamide polymer C-1 was used in terms of solid content weight ratio of A-1: C-1 = 5.
The mixture was mixed at 0:50 to obtain a surface sizing agent. The properties are shown in Table 1.

Comparative Example 2 Anionic sizing agent A-1 of Example 1 and its properties are shown in Table 1.
Shown in

Comparative Example 3 Zwitterionic acrylamide polymer B- of Example 1
Table 1 shows the properties.

Comparative Example 4 The anionic sizing agent A-2 of Example 6 and its properties are shown in Table 1.
Shown in

Comparative Example 5 Zwitterionic acrylamide polymer B- of Example 5
2. The properties are shown in Table 1.

Comparative Example 6 The amphoteric acrylamide polymer B- of Example 7
Table 3 shows the properties.

Comparative Example 7 Zwitterionic acrylamide-based polymer B- of Example 8
4. The properties are shown in Table 1.

Comparative Example 8 Cationic acrylamide polymer B- of Example 9
Table 5 shows the properties.

[0047]

[Table 1]

<Evaluation of Performance of Surface Sizing Agent> Example 1
-9, Comparative Examples 1-8, and Reference Examples 1-2, performance evaluation was performed.

(1) Base paper for surface sizing Acid high-quality paper Uncoated high-quality paper Basis weight 60 g / m ² Sekihito sizing degree 3 seconds Neutral high quality paper Uncoated high-quality paper Basis weight 60 g / m ² Sukihito sizing degree 4 Second medium paper Uncoated medium paper Basis weight 49 g / m ² Stekihito sizing degree 0.5 sec

(2) Surface sizing method (a) Evaluation on acidic high-quality paper The surface sizing agents of Examples 1 to 9 and Comparative Examples 1 to 8 were applied so that the amount of adhesion was 0.45 g / m ² in solid content. The coating liquid diluted with water was coated on both sides of acidic high-quality paper using a roll coater, and dried at 90 ° C. for 1 minute with a rotary dryer to perform surface sizing. Test paper surface sizing agent application amount,
Table 2 shows the paper quality evaluation. (B) Evaluation on neutral high-quality paper A coating liquid was prepared by diluting the surface sizing agents of Examples 1 to 9 and Comparative Examples 1 to 8 with water so that the amount of adhesion was 0.45 g / m ² in solid content. Then, both sides were coated on neutral high-quality paper using a roll coater, and dried at 90 ° C. for 1 minute with a rotary dryer to perform surface sizing. Test paper surface sizing agent application amount,
Table 3 shows the paper quality evaluation. (C) Evaluation with medium paper A coating liquid obtained by diluting the surface sizing agents of Examples 1 to 9 and Comparative Examples 1 to 8 with water so that the adhesion amount becomes 0.5 g / m ² in solid content, Neutral high-quality paper was coated on both sides using a roll coater, dried at 90 ° C. for 1 minute with a rotary dryer, and subjected to surface sizing. Test paper surface sizing agent application amount,
Table 4 shows the paper quality evaluation.

(3) Evaluation method of paper quality of surface sizing paper Size effect: Stekimt method JIS P-8122-
Anti-slip property according to 1976: Barrier property according to JIS P-8147-1994 Air permeability JIS P-8117-198
Oil resistance according to 0: One drop of toluene is dropped on paper and the time until toluene is absorbed in the paper is measured.

[0052]

[Table 2]

[0053]

[Table 3]

[0054]

[Table 4]

[0055]

The surface sizing agent of the present invention comprises a mixed ion complex of an anionic sizing agent (A) and an acrylamide polymer (B) having a cationic group and / or a zwitterionic group. There is a feature. The surface sizing agent of the present invention is used in various size pressing processes in papermaking processes, gate roll coating, calendar coating, etc., and at the same time as imparting a strong sizing effect, it can significantly improve barrier properties, oil resistance and the like. is there.

Claims (2)

[Claims] 1. An anionic sizing agent (A) and an acrylamide polymer (B) having a cationic group and / or a zwitterionic group as main components, and a mixture of the components (A) and (B). A surface sizing agent comprising an ion complex. 2. The compounding weight ratio of the anionic sizing agent (A) to the acrylamide polymer (B) having a cationic group and / or a zwitterionic group is (A) :( B) = 20 to
The surface sizing agent according to claim 1, wherein the ratio is 80:95 to 5.