JPH06136335A - Adhesive for paper tube - Google Patents

Abstract

PURPOSE:To provide an adhesive for paper tube having excellent compatibility with the constituent sodium silicate, high pressure resistance and high initial tack. CONSTITUTION:The adhesive is produced by mixing 100 pts.wt. (in terms of the solid matter) emulsion of a styrene/(meth)acrylate/(meth)acrylamide copolymer resin mainly consisting of repeating units of styrene, repeating units of (meth)acrylate and repeating units of (meth)acrylamide with 50-800 pts.wt. sodium silicate.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a paper tube adhesive used for manufacturing a paper tube by winding a cardboard around a metal core rod while adhering the cardboard, and more specifically, styrene, (meth)
TECHNICAL FIELD The present invention relates to a high pressure-resistant paper tube adhesive prepared by blending styrene- (meth) acrylic acid ester- (meth) acrylamide copolymer resin emulsion mainly composed of acrylic acid ester and (meth) acrylamide with sodium silicate. It is a thing.

[0002]

2. Description of the Related Art Generally, starch, polyvinyl alcohol, vinyl acetate emulsion and the like are used as adhesives for paper tubes. The performance required of these adhesives for paper tubes is that they are excellent in high-speed adhesiveness on the work side, and on the other hand in performance, pressure resistance of the paper tube such as flat pressure resistance, buckling strength, bending strength, etc. is strongly required. Has been. In particular, the pressure resistance of paper tubes has been required to be higher in recent years as the needs of the market have become more sophisticated.

Conventionally, the following two means have been taken as a method for improving the pressure resistance of a paper tube. One of them is a method of improving the quality of the paper for paper tube, and the other is a method of increasing the hardness of the adhesive film, that is, the elastic modulus of the film. However, the former method of improving the quality of the paper core paper has a drawback that the pressure strength is increased, but the cost is high, and the latter method of increasing the elastic modulus of the adhesive film has a limit in improving the pressure strength. , Neither was satisfactory.

[0004]

DISCLOSURE OF THE INVENTION The present invention overcomes the above-mentioned drawbacks of conventional adhesives for paper tubes, has a fast initial adhesive force, has a high dry film elastic modulus, and is excellent in paper impregnation property. It is an object of the present invention to provide a copolymer resin emulsion-based high pressure resistant paper tube adhesive useful as a tube adhesive.

[0005]

Means for Solving the Problems As a result of intensive studies to solve the above problems, the present inventors have found that a vinyl-based monomer mixture containing styrene, (meth) acrylic acid ester, and (meth) acrylamide. The copolymer resin emulsion composition obtained by blending a specific amount of sodium silicate with respect to the copolymer resin emulsion obtained by emulsion polymerization is known to be able to solve the above-mentioned problems, leading to the completion of the present invention. It was

That is, according to the present invention, styrene- (meth) acrylic acid ester-containing styrene, (meth) acrylic acid ester and (meth) acrylamide as main constituent units.
The present invention relates to a paper tube adhesive obtained by mixing 50 to 800 parts by weight of sodium silicate with 100 parts by weight of a solid content of a (meth) acrylamide copolymer resin emulsion.

In order to improve the pressure resistance of a paper tube, the present invention uses a styrene- (meth) acrylic acid ester- (meth) acrylamide copolymer resin emulsion instead of a conventional vinyl acetate resin emulsion. It is characterized by blending sodium silicate.

The styrene- (meth) acrylic acid ester- (meth) acrylamide copolymer resin emulsion used in the present invention can be produced by a conventional emulsion polymerization method. It is meant to contain both acid ester and methacrylic acid ester) and (meth) acrylamide (which means to contain both acrylamide and methacrylamide) as main constituent units.

The (meth) acrylic acid ester used for producing the copolymer resin emulsion is preferably a (meth) acrylic acid alkyl ester having an alkyl group having 4 or more carbon atoms, specifically acrylic. Examples thereof include butyl acid, butyl methacrylate, 2-ethylhexyl acrylate, 2-ethylhexyl methacrylate, octyl acrylate, octyl methacrylate and the like. Two or more kinds of (meth) acrylic acid ester may be mixed and used.

Examples of (meth) acrylamide used for producing the copolymer resin emulsion include acrylamide and methacrylamide. The reason why (meth) acrylamide is used as an essential component as a monomer component is to improve the initial adhesiveness to paper.

The proportions of styrene, (meth) acrylic acid ester and (meth) acrylamide used are based on the weight of the styrene- (meth) acrylic acid ester- (meth) acrylamide copolymer resin and the styrene units and (meth) acrylic acid. Used so that the total of ester units is the main component,
Preferably, the total amount of styrene units and (meth) acrylic acid ester units is 80 to 99.% based on the weight of the copolymer resin.
5% by weight, 0.5 to 20 (meth) acrylamide units
% By weight, more preferably 90 to 98% by weight and 2 to 10% by weight of (meth) acrylamide units based on the weight of the copolymer resin, the total amount of styrene units and (meth) acrylic acid ester units. Used for.

When the content of (meth) acrylamide is less than 0.5% by weight based on the weight of the copolymer resin, the initial adhesive force cannot be obtained, and when it exceeds 20% by weight, the viscosity of the obtained emulsion is It is not preferable because it goes up significantly.

The ratio of styrene units to (meth) acrylic acid ester units in the copolymer resin is 20 to 6 styrene units.
0% by weight, preferably 30 to 50% by weight, (meth) acrylic acid ester unit 40 to 80% by weight, preferably 50 to
It is 70% by weight.

The copolymer resin emulsion of the present invention can be produced by a conventional emulsion polymerization method. At the time of emulsion polymerization, a polymerization initiator is usually used, and any of those generally used for emulsion polymerization can be used. Typical polymerization initiators include water-soluble inorganic peroxides or persulfates such as hydrogen peroxide, potassium persulfate and ammonium persulfate, organic peroxides such as cumene hydroperoxide and benzoyl peroxide, and azobisisosulfate. Examples thereof include azo compounds such as butyronitrile. The amount of the polymerization initiator used is preferably 0.1 to 20% by weight based on the total weight of the monomer components. It is needless to say that a method generally known as a redox polymerization method using these polymerization initiators in combination with a metal ion and a reducing agent may be used.
Further, the above-mentioned monomer components may be added all at once, or in a divided manner, or continuously by dropwise addition. Emulsion polymerization is usually performed at a temperature of 60 to 90 ° C.

The styrene- (meth) acrylic acid ester- (meth) acrylamide copolymer resin emulsion referred to in the above description is a copolymer resin emulsion obtained by arbitrarily copolymerizing the fourth monomer component. May be. Here, the fourth monomer component is acrylic acid, methacrylic acid, itaconic acid, sodium vinyl sulfonate, 2-acrylamide 2-methylpropane-sulfonic acid, sodium p-styrene sulfonate, N-methylol (meth) acrylamide. And hydrophilic vinyl monomers such as hydroxyethyl (meth) acrylate. When the monomer component of the fourth component is used, its amount is preferably 10% by weight or less based on the total weight of the monomer components.

The paper tube adhesive of the present invention is a styrene- (meth) acrylic acid ester- (meth) acrylamide copolymer resin emulsion mainly composed of styrene, (meth) acrylic acid ester and (meth) acrylamide. Sodium silicate 50 to 50 parts by weight of solid content
It is adjusted by blending 800 parts by weight. When the content of sodium silicate is less than 50 parts by weight, the pressure resistance of the paper tube is insufficient, and when it exceeds 800 parts by weight, there is a problem in the initial adhesive strength as an adhesive, which is not preferable.

Examples of the sodium silicate include water glass, sodium metasilicate and its hydrate, sodium orthosilicate and the like.

The reason for adding sodium silicate to the copolymer resin emulsion is not only to increase the elastic modulus of the adhesive film, but also to act as a paper strength enhancer due to the excellent effect of sodium silicate, and to comprehensively This is because the withstand pressure strength of is increased.

The paper tube adhesive of the present invention does not have a problem that even if sodium silicate is added to the copolymer resin emulsion, the viscosity increases at the time of mixing to cause gelation. In addition, the paper tube adhesive of the present invention has a fast initial adhesive force, a high elastic modulus of the dry film,
Further, it has excellent impregnation properties into paper and is useful as an adhesive for paper tubes, especially as an adhesive for high pressure paper tubes.

If desired, the paper tube adhesive of the present invention may contain additives such as an antifoaming agent, a preservative, an inorganic extender pigment, and a coloring pigment.

[0021]

The present invention will be described in more detail with reference to examples. In addition, the part in an Example shows a weight part unless there is particular notice.

Synthesis Example 1 Synthesis of Emulsion [I] In a 1 liter separable flask equipped with a stirrer, thermometer, reflux condenser, dropping funnel, 150 ion-exchanged water was added.
A part was charged and the temperature was raised to 80 ° C. Ion-exchanged water 1
00 parts, anionic emulsifier Rebenol WZ (Kao Corporation)
A mixed emulsion of 2 parts, 100 parts of styrene, 95 parts of 2-ethylhexyl acrylate, 5 parts of methacrylic acid and 15 parts of acrylamide was added dropwise over 4 hours. On the other hand, 5 parts of a 5% ammonium persulfate aqueous solution was added at the same time when the dropping of the mixed emulsion was started to start emulsion polymerization. Then, 30 parts of a 5% ammonium persulfate aqueous solution was added dropwise over 4 hours. During this period, the temperature in the container was kept at 80 ° C, and was kept at 80 ° C for 1.5 hours after the dropping was completed. Then, cooling was started, and after cooling to 30 ° C., 0.5 part of aqueous ammonia was added. The solid content concentration of the obtained copolymer resin emulsion was 43.2%, and the viscosity was 3100 cps (BH viscometer, 10 revolutions, 30 ° C., the same below).

Synthesis Example 2 Synthesis of emulsion [II] The same reaction as in Example 1 was carried out except that the amount of acrylamide used in Example 1 was increased to 20 parts. The solid content concentration of the obtained copolymer resin emulsion is 43.8.
%, The viscosity was 5600 cps.

Synthesis Example 3 Synthesis of emulsion [III] The same reaction as in Example 1 was carried out except that butyl acrylate was used instead of 2-ethylhexyl acrylate in Example 1. The obtained copolymer resin emulsion had a solid content concentration of 43.1% and a viscosity of 2600 cps.

Synthesis Example 4 Synthesis of emulsion [IV] In a 1-liter separable flask equipped with a stirrer, a thermometer, a reflux condenser, and a dropping funnel, a 10% aqueous solution of completely saponified polyvinyl alcohol (PVA 117, manufactured by Kuraray). Four
00 parts, 100 parts of deionized water and 10 parts of sodium acetate
% 2.5% aqueous solution was charged and the temperature was raised to 70 ° C. Then, 2.5 parts of 30% hydrogen peroxide solution and 10 parts of 10% tartaric acid aqueous solution were added, and immediately 400 parts of vinyl acetate was added to 4 parts.
Dropped over time. On the other hand, 2.5 parts of 30% hydrogen peroxide solution was added to water, and an aqueous solution having a total amount of 50 parts was added dropwise over 4 hours. During this period, the inside of the container was kept at 80 to 85 ° C., and after the dropping was finished, it was kept at 80 to 85 ° C. for 1.5 hours. Then, cooling was started, and after cooling to 30 ° C., 50 parts of dibutyl phthalate was added. The obtained vinyl acetate resin emulsion had a solid content concentration of 48.2% and a viscosity of 9200 cps.

Synthesis Example 5 Synthesis of emulsion [V] The same reaction as in Example 1 was carried out except that acrylamide was not used. The solid content concentration of the obtained copolymer resin emulsion was 41.5% and the viscosity was 82.
It was 0 cps.

Examples 1 to 5 and Comparative Examples 1 to 2 Sodium silicate (water glass No. 3, manufactured by Nippon Kagaku Kogyo Co., Ltd.) was added to 100 parts of the solid content of each resin emulsion obtained in the above Synthesis Examples 1 to 5. Was gradually added at a ratio shown in Table 1 to prepare an adhesive. 2 sheets of paper for paper tube are prepared using the obtained adhesive.
The pieces were laminated and the ring crush strength and the initial adhesive strength were measured. The results are shown in Table 1.

[0028]

[Table 1]

As is clear from Table 1, the adhesive obtained in the present invention is excellent in miscibility with sodium silicate, and has high pressure resistance and high initial adhesive strength.

[0030]

The paper tube adhesive of the present invention can be used as a paper tube adhesive, especially as a high pressure paper tube adhesive, since it can significantly increase the pressure resistance of paperboard with a single liquid.

Claims (2)

[Claims] 1. A solid content of 100 parts by weight of a styrene- (meth) acrylic acid ester- (meth) acrylamide copolymer resin emulsion mainly composed of styrene, (meth) acrylic acid ester and (meth) acrylamide. An adhesive for paper tubes, which comprises 50 to 800 parts by weight of sodium silicate. 2. The paper tube adhesive according to claim 1, wherein the copolymer resin contains 0.5 to 20% by weight of a (meth) acrylamide unit based on the weight of the copolymer resin.