JP2000073295A - Damp-proof composition for paper coating - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a copolymer latex capable of providing paper with a damp- proof layer having excellent moisture resistance and blocking resistance and defibration properties recoverable as a waste paper. SOLUTION: This damp-proof composition for paper coating comprising a copolymer latex (A) containing a particle having a core/shell structure composed of a core part having 40-90 deg.C glass transition temperature and a shell part having -40 to 20 deg.C glass transition temperature, a synthetic zeolite (B) and a wax emulsion (C) is applied to a base paper to give a damp-proof paper having excellent defibration properties required for recovering a waste paper and improved moisture resistance and not causing blocking.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a composition for forming a paper moisture-proof layer and a moisture-proof paper. More specifically, the present invention is to form a moisture-proof layer with a specific moisture-proof composition on a support, for example, high-quality paper, recycled paper, kraft paper, roll paper, glassine paper, cardboard base paper, white paperboard, etc. Another object of the present invention is to provide a moisture-proof paper which is excellent in moisture-proof property, particularly excellent in disintegration required for recovery of used paper, and can be reused.

[0002]

2. Description of the Related Art Moisture proof paper is applied to various uses such as wrapping paper, and its demand has been increasing in recent years. Hitherto, a moisture-proof paper having a moisture-proof layer containing a synthetic rubber and a wax has been known (Japanese Patent Publication No. 55-22597, Japanese Patent Application Laid-Open No. 07-279093). This moisture-proof paper is obtained by applying a rubber latex composition comprising a synthetic rubber latex and a wax-based emulsion to the surface of a base paper and drying. However, this rubber latex composition has problems such as blocking between the moisture-proof papers during storage and blocking between the contents and the moisture-proof paper during packaging. If the glass transition temperature (Tg) of the latex is increased to avoid this blocking, the moisture resistance of the paper becomes insufficient. Further, in order to improve the blocking resistance, a method using a silica-modified resin in combination (Japanese Patent Application Laid-Open No. Hei 8-302592) is disclosed. However, although this method improves the blocking property, the moisture resistance is still insufficient. On the other hand, recently, from the viewpoints of resource saving and prevention of environmental pollution, there is a strong demand for moisture-proof paper capable of reusing resources, that is, recovering used paper. What can be recovered as used paper is one in which the pulp forming the paper is easily disintegrated into single fibers.

[0003] However, polyethylene, polypropylene,
Or moisture-proof paper obtained by coating a high molecular compound such as polyvinylidene chloride on the base paper has sufficient moisture-proof,
The pulp does not sufficiently disintegrate into single fibers and remains in bundled fibrous flocks, so that it cannot be recovered as used paper.
In order to solve these problems, a method for producing a moisture-proof paper by applying an emulsion containing a paraffin wax having a specific composition (Japanese Patent Laid-Open No. 50-37111), a method for producing a base paper with a certain kind of synthetic rubber latex and wax, Of moisture-proof paper coated with a mixture of emulsions (packaging technology, Showa 5
Sep. 7, 2007, 42-46). However, although these techniques have a decent moisture-proof property, their disintegration properties are still insufficient, and they have not yet provided moisture-proof paper that can recover used paper. Also, a specific range of T
A method in which a wax-based emulsion is blended with an acrylic emulsion having g and coated (Japanese Patent Laid-Open No. 06-28789).
0) and a method in which a wax emulsion is blended with an acrylic emulsion having a gel fraction in a specific range (JP-A-07-133600), or a styrene emulsion and a wax emulsion are prepared by devising solubility in water. A method of applying an aqueous emulsion containing the same (JP-A-05-302299, JP-A-07-119080) and the like are disclosed.

[0004] In any of these techniques, waxes are added and the moisture-proof property depends on the water-repellent layer of the wax.
When stacking paper bundles wrapped with moisture-proof paper, slipping is likely to occur between the coated and non-coated layers of the moisture-proof paper. Accidents such as collapse or falling of the package may occur. Further, a wax bleed phenomenon (a phenomenon in which the wax present inside the moisture-proof layer moves to the surface of the moisture-proof layer due to the passage of time or a change in temperature)
Thereby, the adhesiveness of the coating layer surface of the moisture-proof paper is reduced,
When wrapping copy paper or the like, the wax migrates to the surface of the copy paper, and the printing becomes unclear, or the label is immediately peeled off even if a label or the like is attached to the coated surface.

[0005]

DISCLOSURE OF THE INVENTION The present invention provides an excellent disintegration required for recovery of waste paper, high moisture resistance, no reduction in moisture resistance at the time of folding, no blocking, and a wax emulsion. The purpose of the present invention is to provide a paper coating moisture-proof composition for producing a moisture-proof paper which does not cause any adverse effect due to the slip property or the wax bleed phenomenon between the coated layer and the uncoated layer even if added. is there.

[0006]

Means for Solving the Problems The present inventors have made intensive studies to solve the above-mentioned problems in the conventional moisture-proof paper, and as a result, have found that a composition containing a specific copolymer latex and a synthetic zeolite has been obtained. Have found that the above-mentioned problem can be solved, and have further studied to complete the present invention. That is, the present invention provides (1) a moisture-proof composition for paper coating containing the following components (A), (B) and (C): component (A); a glass transition temperature (Tg) of 40 to 40; Copolymer latex containing core-shell structured particles consisting of a core part at 90 ° C. and a shell part having a Tg of -40 to 20 ° C. (B) component; synthetic zeolite (C) component; wax emulsion, (2) The compounding weight ratio of the component (A) to the component (B) is 99.5 to 80: 0.5.
And the compounding weight of the component (C) is 0.1 to 20 with respect to 100 parts by weight of the total of the components (A) and (B).
(3) The composition according to (1), wherein the core in the component (A) is an aliphatic conjugated diene monomer 3-1.
5 parts by weight, ethylenically unsaturated carboxylic acid monomer 0.2
To 7 parts by weight and other ethylenically unsaturated monomers 8
It is obtained by emulsion-polymerizing a monomer mixture (a) consisting of 0 to 96 parts by weight, wherein the shell portion is 3 to 60% by weight of an aliphatic conjugated diene-based monomer, and an ethylenically unsaturated carboxylic acid monomer (1) which is obtained by emulsion polymerization of a monomer mixture (b) consisting of 0.2 to 7% by weight of a monomer and 35 to 69% by weight of other ethylenically unsaturated monomers.
The composition according to (1), wherein the core-shell structured particles in the component (4) (A) are composed of 5 to 50% by weight of a core portion and 50 to 95% by weight of a shell portion. (5) The composition according to the above (1), wherein the minimum film-forming temperature of the copolymer latex of the component (A) is 0 to 60 ° C.
(6) The copolymer latex of the component (A) has a gel content of 8
The composition according to the above (1), which is 0 to 100%;
(7) The composition according to (1), wherein the copolymer latex of the component (A) has an average particle diameter of 0.05 to 0.5 μm; ~
(1) having a surface tension of 60 mN / m;
The composition as described above, wherein the synthetic zeolite of the component (9) (B) has an average particle diameter of 0.1 to 20 μm and a specific surface area of 5 to 500.
wherein those of m ² / g (1) The composition according, and (10) wherein (1), wherein the paper coating moisture resistant composition moisture-proof paper obtained by coating on a paper support ,.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, a method for producing a copolymer latex according to the present invention will be described in detail. Examples of the conjugated diene monomer used for the monomer mixtures (a) and (b) in the present invention include 1,3-butadiene, isoprene, 2-chloro-1,3-butadiene, and 2-methyl- Examples thereof include those conventionally used in the production of latex, such as 1,3-butadiene. These conjugated diene monomers may be used alone or in combination of two or more. In the present invention, 1,3-butadiene is particularly preferably used. Such a conjugated diene monomer is used for imparting appropriate elasticity and film hardness to the obtained copolymer. Monomer mixture (a)
The amount of the conjugated diene-based monomer used is usually in the range of 3 to 15% by weight, preferably 6 to 12% by weight, and the amount of the conjugated diene-based monomer used in the monomer mixture (b) is Is usually in the range of 30 to 60% by weight, preferably 32 to 55% by weight. When the amount of the conjugated diene-based monomer used is less than 3% by weight in the monomer mixture (a), a flexible and uniform film may not be obtained. Is poor, and in particular, the moisture-proof property may be significantly reduced due to bending of the paper. On the other hand, when the content is more than 15% by weight, the disintegration required for the recovery of the used paper is inferior, and at the same time, the blocking resistance of the moisture-proof paper may be reduced. When the amount of the conjugated diene-based monomer in the monomer mixture (b) is less than 30% by weight, a flexible film may not be obtained, and as a result, the moisture-proof paper has poor moisture-proof properties. Inferiority, especially when the paper is bent, the moisture-proof property may be significantly reduced. On the other hand, when the usage amount is more than 60% by weight, the disintegration required for the recovery of the used paper is inferior, and the blocking resistance of the moisture-proof paper may be inferior.

The ethylenically unsaturated carboxylic acid monomer used in the present invention includes, for example, monocarboxylic acids such as (meth) acrylic acid and crotonic acid, and dicarboxylic acids such as maleic acid, fumaric acid and itaconic acid. And anhydrides thereof, for example, monoesters of dicarboxylic acids such as methyl maleate and methyl itaconate, ie, half esters. It is desirable that these ethylenically unsaturated carboxylic acid monomers include an ethylenically unsaturated dicarboxylic acid and (meth) acrylic acid. Ethylenically unsaturated carboxylic acid monomers other than ethylenically unsaturated dicarboxylic acid and (meth) acrylic acid can also be used in combination with ethylenically unsaturated dicarboxylic acid and (meth) acrylic acid. The amount of the ethylenically unsaturated carboxylic acid monomer used in the present invention is 0.1% in the monomer mixtures (a) and (b).
It is in the range of 2 to 7% by weight, preferably 0.5 to 4% by weight. When the amount of the ethylenically unsaturated carboxylic acid monomer (2) used in each monomer mixture is less than 0.2% by weight, the resulting copolymer latex and the machine of the coating composition according to the present invention are used. If the thermal stability is not sufficient, and if it exceeds 7% by weight, the moisture-proofing properties of the moisture-proof paper may decrease. When the ethylenically unsaturated dicarboxylic acid and the (meth) acrylic acid are used in combination, the ratio of the ethylenically unsaturated dicarboxylic acid to the (meth) acrylic acid is usually ethylenically unsaturated dicarboxylic acid / (meth) acrylic acid = 10/90 to 90/10 (% by weight), preferably 2
It is about 5/75 to 75/25 (% by weight).

The ethylenically unsaturated monomer other than the ethylenically unsaturated carboxylic acid monomer used in the present invention includes, for example, aromatic vinyl compounds such as styrene and α-methylstyrene, for example, methyl acrylate and acrylic Unsaturated carboxylic acid alkyl ester compounds such as ethyl acrylate, butyl acrylate, 2-hydroxyethyl acrylate, methyl methacrylate, 2-hydroxyethyl methacrylate and glycidyl methacrylate, for example, acrylamide, methacrylamide, N, N-dimethyl Ethylenic unsaturated carboxylic amide compounds such as acrylamide and N-methylol acrylamide, for example, carboxylic acid vinyl esters such as vinyl acetate, for example, acrylonitrile, vinyl cyanide compounds such as methacrylonitrile, for example, methyl Minoechiru (meth) acrylate, dimethylaminoethyl (meth) acrylate, 2-
Examples include ethylenically unsaturated amine compounds such as vinylpyridine. These may be used alone or in combination of two or more. In the present invention, among these ethylenically unsaturated monomers, styrene is preferable as the aromatic vinyl compound, methyl methacrylate is preferable as the unsaturated carboxylic acid alkyl ester compound, and acrylonitrile is preferable as the vinyl cyanide compound. Used. The amount of the ethylenically unsaturated monomer used is usually from 80 to 96 in the monomer mixture (a).
%, Preferably 83 to 93% by weight, and in the monomer mixture (b), usually 35 to 69% by weight, preferably 41 to 65% by weight. When the amount of the ethylenically unsaturated monomer used is less than 80% by weight in the monomer mixture (a), the disintegration required for recovery of the used paper may be poor, and when it exceeds 96% by weight, In addition, the moisture-proof paper may be inferior in moisture-proof properties, and the moisture-proof properties may be greatly reduced particularly when the paper is folded.

When the amount of the ethylenically unsaturated monomer is less than 35% by weight in the monomer mixture (b), the disintegration required for the recovery of waste paper is inferior and the resistance of the moisture-proof paper is low. In some cases, the blocking property is inferior, and when it exceeds 69% by weight, the moisture-proof paper is inferior in moisture-proof property, and in particular, the moisture-proof property at the time of folding may be greatly reduced. The copolymer latex of the present invention can be emulsified by a conventionally known emulsion polymerization method, for example, by adding a monomer mixture, a polymerization chain transfer agent, a polymerization initiator, an emulsifier and the like in an aqueous medium such as water. It can be produced by polymerization. As the polymerization chain transfer agent, an ordinary chain transfer agent generally known in emulsion polymerization can be used. Examples of such a chain transfer agent include mercaptocarboxylic acids such as 2-mercaptopropionic acid or salts thereof (for example, ammonium mercaptoacetate), and mercaptandicarboxylic acids such as mercaptosuccinic acid or salts thereof (for example, mercaptandicarboxylic acid). Salts, etc.), for example, mercaptans having a hydroxyl group in the molecule such as 2-mercaptoethanol, for example, mercaptans having an amino group in the molecule such as 2-mercaptoethylamine, for example, thioglycolic acid, 3,3′-thiodipropion Monosulfides having a carboxyl group in the molecule such as acids or salts thereof, for example, monosulfides having a hydroxyl group in the molecule such as β-thiodiglycol, such as monosulfides having an amino group in the molecule such as thiodiethylamine , Example For example, disulfides having a carboxyl group in a molecule thereof such as dithiodiglycolic acid and 2,2′-dithiodipropionic acid or salts thereof, and monosulfides and disulfides such as thiodiglycolic anhydride. Disulfides having a carboxyl group and an amino group in the molecule such as anhydrides, for example, D-, L- or DL-cystine, for example, chloromethanol,
Halogenated hydrocarbons having a hydroxyl group in the molecule such as chloroethanol, for example, monochloroacetic acid, dichloroacetic acid, chlorofumaric acid, chloromaleic acid, halogenated hydrocarbons having a carboxyl group in the molecule such as chloromalonic acid or salts thereof Acid anhydrides of halogenated hydrocarbons such as chloromaleic anhydride; monothiols such as hexylmercaptan, octylmercaptan, n-dodecylmercaptan, t-dodecylmercaptan, for example, 1,10-decanediol , At least two mercaps in the molecule, such as dithiols such as triglycoldimercaptan, trithiols such as trimethylolpropane tristhioglycolate, for example tetrathiols such as pentaerythritol tetrakisthioglycolate. Polythiol having a group, for example, dimethylxanthogen disulfide, xanthogen disulfide such as diethylxanthogen disulfide, thiuram disulfide such as tetramethylthiuram disulfide, for example, halogenated hydrocarbon such as carbon tetrachloride, carbon tetrabromide, for example, mercaptoacetic acid 2- Mercaptocarboxylic acid alkyl esters such as ethylhexyl ester and tridecyl mercaptopropionate; for example, mercaptocarboxylic acid alkoxyalkyl esters such as mercaptoacetic acid methoxybutyl ester and mercaptopropionic acid methoxybutyl ester; and carboxylic acids such as octanoic acid 2-mercaptoethyl ester Acid mercaptoalkyl ester and α-methylstyrene dimer, terpinolene, α-te Pinene, γ
-Terpinene, dipentene, anisole, allyl alcohol and the like.

These chain transfer agents are used alone or in combination of two or more. Among these chain transfer agents, monothiol, polythiol, xanthogen disulfide, thiuram disulfide, 2-ethylhexyl mercaptoacetate, 2-mercaptoethyl octanoate, methoxybutyl mercaptoacetate,
Methoxybutyl mercaptopropionate, α-
Methylstyrene dimer, terpinolene and the like are preferably used. The amount of the chain transfer agent to be used is generally 0.05 to 20 parts by weight, preferably 0.1 to 15 parts by weight, based on 100 parts by weight of the total amount of the monomer mixtures (a) and (b). And most preferably from 0.2 to 10 parts by weight. The polymerization initiator is not particularly limited,
For example, inorganic persulfates such as potassium persulfate, sodium persulfate and ammonium persulfate; organic peroxides such as cumene hydroperoxide and benzoyl peroxide; and azo-based initiators such as azoisobutyronitrile. Can be used. These can be used alone or 2
More than one species can be used in combination. Of these, persulfates such as potassium persulfate, sodium persulfate and ammonium persulfate are preferably used from the viewpoint of polymerization stability. The above-mentioned polymerization initiator can also be used as a so-called redox polymerization initiator which is combined with a reducing agent such as sodium bisulfite and ferrous sulfate. The amount of the polymerization initiator used is 100% of the total monomer mixture.
It is usually about 0.1 to 5 parts by weight, preferably about 0.2 to 3 parts by weight, per part by weight.

In the present invention, the emulsifier used in the emulsion polymerization is not particularly limited either. For example, anionic surfactants such as sodium dodecylbenzenesulfonate, sodium lauryl sulfate, sodium dodecyldiphenyletherdisulfonate, and the like Examples of nonionic surfactants such as oxyethylene alkyl esters and polyoxyethylene alkyl aryl ethers and amphoteric surfactants include alkyl betaine-type salts such as lauryl betaine and stearyl betaine, and lauryl-
β-alanine, lauryldi (aminoethyl) glycine,
Amino acid type such as octyldi (aminoethyl) glycine and the like can be mentioned. These can be used alone or in combination of two or more. Of these emulsifiers, sodium dodecylbenzenesulfonate or sodium dodecyldiphenyletherdisulfonate is particularly preferably used. The amount of the emulsifier to be used is generally about 0.05 to 2.5 parts by weight, preferably about 0.1 to 1.5 parts by weight, per 100 parts by weight of the total monomer mixture used. . In the production of the polymer latex of the present invention, if necessary, the emulsion polymerization may be performed in the presence of a chelating agent such as sodium ethylenediaminetetraacetate, a dispersant such as sodium formaldehyde sulfoxylate, or an inorganic salt. Good.

In order to produce the copolymer latex of the present invention, in the first charging stage, the whole amount of the monomer mixture (a) is emulsion-polymerized in an aqueous medium in a polymerization reactor and has a glass transition temperature of 40. C. to 90C, preferably 50C to 80C,
The average particle size of the latex particles is usually 0.01 to 0.3 μm
m, preferably a copolymer latex as a core part having a particle size of 0.05 to 0.2 μm, and subsequently the monomer mixture (b) is prepared by using the copolymer obtained by the first preparation step as seed particles. Addition and emulsion polymerization, the glass transition temperature is -40 ℃ ~ 20 ℃, preferably -30 ℃ ~ 10 ℃ and the average particle diameter of the latex particles is usually 0.05 ~ 0.5 μm,
Preferably, a copolymer latex having a shell portion of 0.1 to 0.3 μm is obtained. As a method of this emulsion polymerization, a divided addition method in which the second stage to the last stage is divided into a plurality of stages and added, a continuous addition system in which the second stage to the last stage are continuously added, or a method in which these are combined There are any of them. In the production of the copolymer latex according to the present invention, the polymerization conversion is preferably about 90% by weight or more, more preferably about 95% by weight or more. The weight ratio of the core part to the shell part of the copolymer latex particles of the present invention is usually 5 to 50 to 95 to 50, preferably 10 to 40 to 90 to 60. If the core portion is less than 5% by weight of the whole, the disintegration required for recovery of the used paper may be poor, and if it exceeds 50% by weight, the moisture-proof paper may be inferior in moisture resistance. When a pH adjuster is used in the production of the copolymer latex of the present invention, for example, an alkaline substance such as ammonia, sodium hydroxide, or potassium hydroxide is used, and the use of ammonia is particularly preferable.

The pH of the copolymer latex is usually 5-1.
0, preferably in the range of 7-9. When the pH value is lower than 5, the mechanical stability of the obtained copolymer latex and the coating composition according to the present invention may not be sufficient, and when it exceeds 10, the moisture resistance may be poor. The surface tension of the obtained copolymer latex is usually 43 to 60 m.
N / m, preferably in the range of 50-60 mN / m.
When the surface tension is less than 43 mN / m, the moisture-proof paper may have poor moisture-proof properties, and in particular, may have poor moisture-proof properties when folded. In the present invention, the minimum film formation temperature (MFT) of the copolymer latex is also important.
° C, preferably in the range of 10 to 50 ° C. When the minimum film formation temperature is lower than 0 ° C., the disintegration may be inferior.
If it is higher, the ability to form a film is reduced and a uniform film is not formed, and therefore, the moisture-proof property may be inferior. The gel content (toluene-insoluble content) of the copolymer latex of the present invention is usually 80 to 100%, preferably 85 to 9%.
The range is 9%. If the gel content is less than 80%, the disintegration of the moisture-proof paper may be poor. The synthetic zeolite (B) used in the moisture-proof paper of the present invention has, for example, a chemical composition M
_{2 O · Al 2 O 3 ·} 2SiO 2 · nH 2 O (M represents an alkali metal, n represents 3-7) include those represented by, is used as a wax bleed inhibitor. Examples of the silica source constituting the synthetic zeolite include sodium (meth) silicate, ultrafine silica, silica gel, silica sol, and water glass, and particularly preferably sodium (meth) silicate and ultrafine silica.

The alumina source of the synthetic zeolite includes sodium aluminate, aluminum hydroxide, aluminum chloride, nitrate, sulfate, and the like, with aluminum hydroxide being particularly preferred. Examples of the alkali source include a sodium salt and a potassium salt, and a sodium salt is particularly preferable. Also, these synthetic zeolites are generally
A type zeolite, Y type zeolite, ZS
It is classified into M-5 type zeolite, and in the present invention, A type zeolite is particularly preferably used. The average particle size of the synthetic zeolite according to the present invention is in the range of 0.1 to 20 μm, preferably 1 to 10 μm. Average particle size is 0.1
If it is less than μm, for example, when processing a paper container, a paper box, etc., when making a ruled line on the paper and bending it along this ruled line,
It may cause the destruction of the moisture-proof coating layer (the breakability of the ruled line), impair the moisture-proof property, and reduce the average particle size to 2
If it is larger than 0 μm, the disintegration may be poor. The specific surface area of the synthetic zeolite used in the present invention is usually 5 to 5.
500m ² / g, preferably in the range of 10 to 100 m ² / g. When the specific surface area of the synthetic zeolite is less than 5 m ² / g, there may be cases where slippage between the coating layer and the non-coating layer due to the wax emulsion or an adverse effect due to the wax bleeding phenomenon occurs, and the specific surface area is 500 m ² / g.
If it is larger, the moisture resistance may decrease. The wax emulsion (C) used in the present invention is obtained by emulsifying a wax. Examples of the wax include paraffin wax, candelilla wax, carnauba wax, rice wax, montan wax, ceresin wax, microcrystalline wax, and petrolactam. And Fischer-Tribush wax, polyethylene wax, montan wax and derivatives thereof, microcrystalline wax and derivatives thereof, hardened castor oil, liquid paraffin, and stearamide, and paraffin wax is particularly preferably used.

The wax emulsion may be prepared by a known method, for example, wax, resin,
The mixture may be melted, for example, by mixing and heating a fluidizing agent, and then emulsified by adding an emulsifier thereto. As the resin, for example, rosin, rosin ester compound, petroleum resin and the like are used, and as the fluidizing agent, for example, polyhydric alcohol, esterified product of polyhydric alcohol and the like are used. After these mixtures are melted, for example, surfactants such as anions, cations, and nonions, or basic compounds such as ammonia, sodium hydroxide, and potassium hydroxide, organic amines, and styrene-maleic acid copolymers are added. By emulsification, a wax emulsion can be obtained. In the moisture-proof paper of the present invention, it is preferable to use the copolymer latex (A) component and the synthetic zeolite (B) component in a weight ratio of 99.5 to 80: 0.5 to 20. More preferably, it is used in a ratio of from 10 to 10: 1.

If the blending ratio of the copolymer latex (A) exceeds 99.5% at this weight blending ratio, the slipperiness between the coated and non-coated layers of the moisture-proof paper is reduced, or wax bleeding occurs. There is a possibility that adverse effects due to the phenomenon may occur. The blending ratio of the copolymer latex was 80%.
When the amount is smaller, the moisture resistance may be poor and may be economically disadvantageous. The compounding amount of the wax emulsion (C) component is preferably 0.1 to 20 parts by weight, preferably 1 to 10 parts by weight, based on 100 parts by weight of the compounded liquid composed of the components (A) and (B). It is more preferred that there be. If the amount is less than 0.1 part by weight, the moisture resistance may be poor. If the amount is more than 20 parts by weight, the disintegration is inferior and the slipperiness between the coated layer and the non-coated layer of the moisture-proof paper decreases. Or harmful effects due to the wax bleed phenomenon may occur. The solid content concentration in the moisture-proof composition for paper coating of the present invention is generally 30 to 70% by weight, preferably 35 to 60% by weight. The coating amount of the moisture-proof composition for paper coating on base paper is usually 3 to 30 g / m ² , preferably 5 to ²⁰ m ² / g. If the coating amount is less than 3 g / m ² , the covering of the base paper surface fibers becomes insufficient, and a sufficient moisture-proof effect may not be obtained. Conversely, if the coating amount exceeds 30 g / m ² , the disintegration is poor. There is. The coating method can be performed by a known method. For example, the coating liquid is applied by a method such as a roll coater, a blade coater, or an air knife coater. After the coating, a moisture-proof layer is formed on the base paper by a drying process to obtain a moisture-proof paper. At this time, the drying temperature is usually 80 ° C. or higher.

[0018]

Next, the moisture-proof composition for paper coating of the present invention will be described in more detail with reference to Examples and Comparative Examples, but the present invention is not limited thereto. In Examples, “%” and “parts” are all based on weight. (I) Method for Producing Copolymer Latex (1) In a 5-liter autoclave purged with nitrogen,
As the preparation of the stage, 1,3-butadiene 3 parts, styrene 26 parts, itaconic acid 1 part, potassium persulfate 0.5 part, water 100 parts, sodium alkylbenzenesulfonate 0.1 part.
One part and 0.1 part of t-dodecyl mercaptan were charged and reacted at 75 ° C. while stirring. Two hours after the start of the reaction, as a second stage preparation, 1,3-butadiene 32 parts, styrene 27 parts, methyl methacrylate 10
Parts, 1 part of acrylic acid and 0.2 parts of -dodecylmercaptan were added to a mixture of sodium alkylbenzenesulfonate at 0.
Added sequentially with 5 parts continuously over 5 hours. Fifteen
After reacting over time, when the polymerization conversion reaches 95% or more (per 100 parts of monomer), the reaction mixture is cooled to 30%.
C. and cooled to pH 8.0 ± 0.5 with aqueous ammonia.
Adjusted to 2. Then, steam was blown into the reaction mixture to remove unreacted monomers, and the reaction mixture was further concentrated until the solid content of the latex became 48%, to obtain a desired copolymer latex (1).

(Ii) Copolymer latex (2) to (1)
Production method of 1) The monomer composition, the amount of the emulsifier and the amount of the polymerization chain transfer agent are shown in [Table 1].
The above copolymer latex (1) except that the amount was changed to the indicated amount
The copolymer latexes (2) to (11) were produced in the same manner as in the above method. The composition and properties of the obtained copolymer latex are shown in Table 1 below. In addition,
The numerical values of each component in Table 1 are parts by dry weight.

[0020] EXAMPLE chemical composition Na ₂ O · Al ₂ to 1 water 27 parts by weight O ₃ · 2SiO ₂
5 parts by weight of a synthetic zeolite (Silton B manufactured by Mizusawa Chemical Co., Ltd.) represented by nH ₂ O (n is an integer of 3 to 7) was added,
Further, 0.125 parts of sodium polyacrylate (Poise 530, manufactured by Kao Corporation) was added as a dispersant, and the mixture was sufficiently stirred with a homomixer to obtain an aqueous dispersion of a synthetic zeolite having a solid content of 18%. Subsequently, the copolymer latex and the synthetic zeolite dispersion were mixed at a ratio of 95: 5 parts by weight, and the mixture was mixed with a wax emulsion (paraffin wax).
After adding 3 parts by weight of EW-1000 (Arakawa Chemical Co., Ltd.) and mixing well, the desired moisture-proof composition for paper coating was obtained.
This aqueous emulsion composition was applied to one side of a kraft paper of 75 g per square meter using a Meyer bar so as to have a coating amount of 15 g / m ^2, and dried at 100 ° C. for 1 minute to prepare a moisture-proof paper. .

Examples 2 to 5 Using each of the copolymer latexes (2) to (5),
A moisture-proof composition for paper coating was prepared in the same manner as in Example 1 using the components shown in Table 2. A moisture-proof paper was prepared in the same manner as in Example 1 using these moisture-proof compositions for paper coating.

Comparative Examples 1 to 6 Using each of the copolymer latexes (6) to (11) and the components shown in Table 2, a moisture-proof composition for paper coating was prepared in the same manner as in Example 1. It was prepared and used to make a moisture-proof paper. Comparative Examples 7 and 8 Using the copolymer latex (1), the weight ratio of the copolymer latex to the synthetic zeolite was 100 in Comparative Example 7;
0, Comparative Example 8 was 70; 30, and the other conditions were the same as in Example 1 to prepare a moisture-proof composition for paper coating. Subsequently, moisture-proof paper was prepared using these.

Comparative Example 9 Copolymer latex (1) having a specific surface area of 600 m ² / g
Was prepared in the same manner as in Example 1 using the synthetic zeolite described above, and a moisture-proof paper was prepared using the composition. Comparative Examples 10 and 11 Using the copolymer latex (2), the compounding weight of the wax emulsion was determined based on 100 parts by weight of the compounding liquid composed of the copolymer latex (2) and the synthetic zeolite.
A moisture-proof composition for paper coating was prepared in the same manner as in Example 1 except that 0.05 part by weight was added for 0, and 25 parts by weight for Comparative Example 11, and moisture-proof paper was prepared using the composition.

Evaluation Test of Moisture-Proof Paper Each physical property of the moisture-proof paper prepared in Examples 1 to 5 and Comparative Examples 1 to 11 was measured by the following methods, and the results are shown in Table 2. (1) Gel component (toluene-insoluble component) The obtained copolymer latex is poured into a glass mold,
A film having a thickness of 0.3 mm was prepared. This film is
It was cut into 3 mm squares and 0.4 g was precisely weighed. The sample was immersed in 100 ml of toluene and shaken in a shaking constant temperature bath at 30 ° C. for 6 hours. Thereafter, the mixture was filtered through a 100-mesh wire gauze, the solid content of the filtrate was obtained, and the gel content was calculated from the solid content of the sol. (2) Glass transition temperature (Tg) The obtained copolymer latex is poured into a glass mold,
A film having a thickness of 1.5 mm was prepared. This film was measured using a scanning differential calorimeter. (3) Minimum film formation temperature (MFT) Measured using a whitening point temperature tester manufactured by Toyo Seiki Seisakusho in accordance with ASTM D-2354-65T. (4) Average particle size Coulter counter MODEL N4 + (Coulter Co., Ltd.)
Was used for the measurement. (5) Moisture Permeability According to JIS Z-0208 (cup method) B method, the measurement was performed with the coated surface outside. As a standard for moisture permeability, 50 g / m ² .
24 hours or less is sufficiently practical. (6) Disintegration 16 g of moisture-proof paper cut into 1 cm x 1 cm is put into 800 ml of water, put in a household mixer, and stirred for 1 minute.
The slurry was taken out, and the presence or absence of undisintegrated materials (film pieces, paper pieces) was visually evaluated according to the following criteria. Completely disintegrated without undisintegrated material: ○ Polymer with 1 mm or more: △ Polymer with 2 mm or more in film form: ×

(7) Blocking resistance The coated and uncoated surfaces of the moisture-proof paper having a size of 10 cm square are brought into contact with each other, pressed at a temperature of 40 ° C. and a pressure of 15 kg / cm ² for 20 minutes and taken out. The state of adhesion of the pieces of paper was observed and evaluated according to the following criteria. When the coated and uncoated surfaces come off easily
: ○ When 20 to 39% of the area of the coated and uncoated surfaces is broken by the paper layer: △ When 40% or more of the area of the coated and uncoated surfaces is broken by the paper layer: × (8) Wax bleeding The coated surface and the non-coated surface of the functional paper were overlapped, passed once through a super calender at 40 ° C. and a linear pressure of 10 kg / cm, and the friction coefficient of the non-coated surface was measured according to the method of JIS P8147. However, the measurement speed was measured under the condition of 100 mm / min. The friction coefficient of the base paper itself as a standard was 0.50. Therefore, the wax bleedability was evaluated according to the following criteria. Friction coefficient 0.40 or more: ○ Friction coefficient 0.3 or more and less than 0.4: Δ Friction coefficient less than 0.3: × From the above Examples and Comparative Examples, the moisture-proof paper obtained by the present invention has a moisture-proof property. It is evident that it is expected to be excellent, without blocking, and to obtain an appropriate coefficient of friction, without any adverse effects due to wax bleeding property, and to have a sufficient degree of disintegration that can be sufficiently recovered as used paper.

[0026]

[Table 1]

[0027]

[Table 2]

[0028]

The moisture-proof paper obtained by the present invention has excellent moisture-proof properties, does not cause blocking, and has excellent disintegration properties, so that it can be recovered as waste paper.

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Juichi Miyoshi 2-17-17, Jusanhoncho, Yodogawa-ku, Osaka-shi, Osaka Takeda Pharmaceutical Co., Ltd. Chemicals Company F-term (reference) 4J038 BA212 CP001 EA011 HA216 MA02 MA08 MA10 MA13 MA14 NA07 PC10 4L055 AG28 AG51 AG63 AG70 AG71 AG76 AG89 AG94 AG97 AH50 AJ02 BE08 EA16 EA17 EA20 EA29 EA32 EA33 FA30 GA47

Claims (10)

[Claims] 1. A moisture-proof composition for paper coating comprising the following components (A), (B) and (C): Component (A); Core having a glass transition temperature (Tg) of 40 to 90 ° C. Latex containing core-shell structured particles consisting of a shell part having a Tg of -40 to 20 ° C. (B) component; synthetic zeolite (C) component; wax emulsion 2. The compounding weight ratio of component (A) to component (B) is as follows:
99.5 to 80: 0.5 to 20, and the compounding weight of the component (C) is 0.1 to 20 parts by weight based on 100 parts by weight of the total of the components (A) and (B). Item 10. The composition according to Item 1. 3. The component (A) wherein the core part is 3 to 15 parts by weight of an aliphatic conjugated diene monomer, 0.2 to 7 parts by weight of an ethylenically unsaturated carboxylic acid monomer and other ethylenically unsaturated monomers. It is obtained by emulsion polymerization of a monomer mixture (a) consisting of 80 to 96 parts by weight of a monomer, wherein the shell part is 3 to 60% by weight of an aliphatic conjugated diene monomer and an ethylenically unsaturated carboxylic acid. 0.2 to 7% by weight of acid monomer and 35 to 69% by weight of other ethylenically unsaturated monomer
The composition according to claim 1, which is obtained by emulsion polymerization of a monomer mixture (b) consisting of: 4. The particles having a core / shell structure in the component (A)
The composition according to claim 1, comprising 5 to 50% by weight of a core portion and 50 to 95% by weight of a shell portion. 5. The composition according to claim 1, wherein the minimum film forming temperature of the copolymer latex of the component (A) is 0 to 60 ° C. 6. The composition according to claim 1, wherein the copolymer latex of the component (A) has a gel content of 80 to 100%. 7. The composition according to claim 1, wherein the copolymer latex of the component (A) has an average particle size of 0.05 to 0.5 μm. 8. The copolymer latex of component (A) contains 43 to
2. The composition according to claim 1, which has a surface tension of 60 mN / m. 9. The synthetic zeolite as the component (B) has an average particle diameter of 0.1 to 20 μm and a specific surface area of 5 to 500 m ² / g.
The composition of claim 1 which is: 10. A moisture-proof paper obtained by applying the moisture-proof composition for paper coating according to claim 1 on a paper support.