JP2002265907A - Adhesive composition, and adhesive tape or label - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an adhesive composition that has excellent adhesion properties, can be used for tack paper, adhesive tapes, etc., and has such redispersibility in water that used paper therewith can be easily defiberized in water for repulping for the purpose of resource conservation or other similar purposes. SOLUTION: This adhesive composition comprises a water-soluble resin (A) obtained by neutralizing a resin having an acid value of >=60 mg KOH/g and a weight average molecular weight of 1,000-50,000, with an alkali metal compound or an aminoalcohol, and a copolymer (B) obtained by copolymerizing (b-1) 40-98.9 wt.% of an alkyl (meth)acrylate having a 4-12C alkyl group, (b-2) 1-20 wt.% of a polymerizable unsaturated carboxylic acid, and (b-3) 0.1-40 wt.% of another copolymerizable monomer [wherein (b-1)+(b-2)+(b-3)=100%; and the weight ratio of water-soluble resin (A) to copolymer (B) or (A)/(B), is 5/95-40/60]. The adhesive composition can be used for an adhesive layer for adhesive tapes or labels.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pressure-sensitive adhesive composition used for various applications such as tack paper and pressure-sensitive adhesive tape, and a pressure-sensitive adhesive tape or label using the composition. In detail, the present invention has excellent adhesiveness and excellent redispersibility in water that can be easily disintegrated into water to facilitate recovery of used paper when repulping for the purpose of resource protection or the like. The present invention relates to an adhesive composition and an adhesive tape or label using the composition. In the present specification,
“(Meth) acrylic acid” means acrylic acid or methacrylic acid.

[0002]

2. Description of the Related Art Tack papers and kraft tapes are widely used in various places. However, in the past, when collecting used papers, there was a problem such as adhesion of an adhesive to a disintegrator, so that it was necessary to remove them as repellent substances. . However, in recent years, the importance of repulping has increased from the viewpoint of effective use of resources, and there has been a demand for an adhesive that can be easily disintegrated into water when repulping to facilitate recovery of waste paper. Efforts have been made. For example, Japanese Patent Application Laid-Open No. 5-156222
Japanese Patent Application Laid-Open No. H10-260, discloses an alkali-soluble adhesive obtained by adding a surfactant capable of imparting plasticity to a copolymer obtained by copolymerizing 70 to 99% by weight of a carboxyl group-containing vinyl monomer such as (meth) acrylic acid. An agent composition is described. However, in this pressure-sensitive adhesive composition, a large amount of a hydrophilic carboxyl group-containing monomer is required, and a large amount of a surfactant must be added to the copolymer. Etc., and bleed out of the surfactant from the substrate also poses a problem. Furthermore,
This composition is a pressure-sensitive adhesive soluble in alkaline water, and is accompanied by contamination of wastewater discharged in a repulping process from waste paper, and thus has a problem in terms of protection of the water environment.

On the other hand, in JP-A-5-70755, as a base polymer, 20 to 99% by weight of alkoxyethyl acrylate, 30 to 1% by weight of styrene sulfonate and 50 to 0% by weight of another copolymerizable monomer. % Is described as being redispersible in water. JP-A-11-124552 and JP-A-11-241053 disclose, as base polymers, alkyl (meth) acrylate, alkoxyethyl (meth) acrylate, adduct of caprolactone of (meth) acrylic acid, and A redispersible pressure-sensitive adhesive comprising a copolymer with (meth) acrylic acid is described. Such redispersible adhesives have the advantage that they can be recovered as a solid by the adhesive film being ruptured or dispersed to an appropriate size in the repulp process, thus preventing wastewater contamination, and contributing to environmental protection and environmental protection. It meets the needs of recycling. However, styrene sulfonic acid and
It is necessary to use a special and relatively expensive monomer such as a caprolactone adduct of acrylic acid, which is not economical.

In general, pressure-sensitive adhesives that emphasize repulpability are designed to increase the hydrophilicity of the base polymer, and therefore contain a relatively large amount of hydrophilic polar groups such as carboxyl groups and hydroxyl groups. In the case of a carboxyl group, hydrophilicity is enhanced by neutralization with an alkaline compound. However, as the neutralizing agent, caustic alkali, ammonia, and amines are generally used, so that the viscosity of the obtained pressure-sensitive adhesive tends to be very high, and the viscosity, gelation, and the like during polymerization or alkali neutralization are increased. The operation is hindered, which is likely to occur.

[0005]

DISCLOSURE OF THE INVENTION The present invention has excellent polymerization stability and a good balance between adhesive properties and redispersibility without using expensive special monomers. It is an object of the present invention to provide a pressure-sensitive adhesive which is redispersed in a size that cannot be observed with the naked eye, does not contaminate water quality, and does not adversely affect the appearance and performance of recycled paper.

[0006]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies to solve the above-mentioned problems of water-soluble or water-redispersible pressure-sensitive adhesives. As a result, the present inventors have found that low molecular weight compounds having an acid value of 60 mg KOH / g or more are obtained. Excellent adhesion due to the composition obtained from a water-soluble resin obtained by neutralizing the above resin with a basic substance having low volatility and an aqueous dispersion of a copolymer containing an acrylic monomer having a specific composition as an essential component The inventors have found that they have physical properties and water redispersibility, and have achieved the present invention. That is, the gist of the present invention is that a water-soluble resin (A) obtained by neutralizing a resin having an acid value of 60 mg KOH / g or more and a weight average molecular weight of 1,000 to 50,000 with an alkali metal compound or amino alcohol and (b) -1) alkyl (meth) acrylate having an alkyl group having 4 to 12 carbon atoms 40 to 9
8.9% by weight and (b-2) polymerizable unsaturated carboxylic acid 1
To (b) a copolymer obtained by copolymerizing 0.1 to 40% by weight of (b-3) and another copolymerizable monomer (b) [provided that (b-1) + (b -2) + (b-3) =
100%], and the weight ratio of the water-soluble resin (A) to the copolymer (B) is (A) / (B) = 5/95 to 40/6.
The present invention relates to a pressure-sensitive adhesive composition or a pressure-sensitive adhesive tape or label having a pressure-sensitive adhesive layer containing the pressure-sensitive adhesive composition.

In a more preferred embodiment of the present invention, the resin constituting the water-soluble resin (A) of the pressure-sensitive adhesive composition of the present invention is a styrene-maleic acid copolymer represented by the following general formula (1): Be united;

Embedded image (Wherein m = 1 to 5, n = 5 to 20, R ₁ and R ₂ are each independently a hydrogen atom or an alkyl group having 1 to 18 carbon atoms (provided that at least _one of R ₁ and R ₂ is hydrogen) And the resin constituting the water-soluble resin (A) are acrylic copolymers, and the copolymer is (a-
1) 6 to 50% by weight of a polymerizable unsaturated carboxylic acid, and (a)
-2) Obtained by copolymerizing 94 to 50% by weight of another polymerizable monomer (however, at least one of (a-1) and (a-2) is an acrylic monomer). It is mentioned.

[0008] In another preferred embodiment of the present invention, the amino alcohol is an amino alcohol having a boiling point of 120 ° C or higher;
(B-1), (b-2) and (b-3) are emulsion-polymerized in the presence of a water-soluble resin (A) and a water-soluble resin (A) in the pressure-sensitive adhesive composition. 1 to 30 parts by weight of the hydrophilic plasticizer (C) is added to 100 parts by weight of the polymer (B); the hydrophilic plasticizer (C) is a nonionic surfactant having an HLB of 8 to 20. Can be mentioned.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail.
The pressure-sensitive adhesive composition of the present invention comprises a water-soluble resin (A) obtained by neutralizing a low molecular weight resin having an acid value of 60 mg KOH / g or more with a basic substance having low volatility, and a specific acrylic monomer Is a component having a copolymer (B) of a monomer containing the following at a predetermined composition ratio, and has excellent adhesive properties and also has water redispersibility. Conventionally, as an adhesive containing a low molecular weight resin having a specific acid value, 3
A pressure-sensitive adhesive obtained by emulsion polymerization of an acrylic monomer in the presence of an auxiliary resin having an acid value of 0 mgKOH / g or more is known (JP-A-63-83180). A heat-sensitive adhesive having a sea-island structure in which a water-soluble resin having an acid value of / g or more and an adhesive component form a sea-island structure is also known (JP-A-11-5959), but each of these neutralizes the resin. Since a volatile base such as ammonia is used as the base, the composition does not have redispersibility in water and differs from the composition of the present invention.

The components constituting the present invention will be described. Component (A): a water-soluble resin obtained by neutralizing a resin having an acid value of 60 mgKOH / g or more and a weight-average molecular weight of 1,000 to 50,000 with an alkali metal compound or amino alcohol. It is an essential component for imparting redispersibility. The resin constituting the component (A) is not particularly limited as long as the resin has an acid value of 60 mgKOH / g or more and has an acidic group such as a carboxyl group in a molecule. An acrylic copolymer, an ethylene-acrylic acid copolymer Polymer, styrene-maleic acid copolymer, isobutylene-maleic acid copolymer, polyurethane resin, polyester resin and the like can be used, among which styrene-maleic acid copolymer or acrylic copolymer is used. preferable.

The weight average molecular weight of the resin used in the present invention is from 1,000 to 50,000. Preferably, 2000
~ 30000, more preferably 3000 ~ 1500
0. When the molecular weight is less than 1000, water resistance,
When the component (A) is used as a protective colloid, the polymerization stability is reduced. If it is higher than 50,000, redispersibility and polymerization stability are reduced. Further, the viscosity of the pressure-sensitive adhesive becomes extremely high, and the fluidity is lowered, which is not preferable.

In order for the adhesive to be redispersible in water,
It is necessary that the acid value of the component (A) is 60 mgKOH / g or more. When the acid value is less than 60 mgKOH / g, the redispersibility in water decreases, and when the component (A) is used as a polymer emulsifier during the polymerization of the component (B), the polymerization stability decreases. Preferably, it is 100 to 500 mgKOH / g.

The styrene-maleic acid copolymer suitably used as the resin constituting the component (A) of the present invention is a copolymer represented by the following general formula (1).

Embedded image (Wherein m = 1 to 5, n = 5 to 20, R ₁ and R ₂ are each independently a hydrogen atom or an alkyl group having 1 to 18 carbon atoms (provided that at least _one of R ₁ and R ₂ is hydrogen) Is an atom).

As the component (A) of the present invention, styrene and maleic anhydride may be copolymerized and then neutralized with a basic compound having low volatility as described below. May be used after neutralized. In this case, the acid value of the styrene-maleic acid copolymer resin is preferably from 200 to 500 mgKOH / g, more preferably from 300 to 500 mgKOH / g.
It is. If the acid value is too low, the redispersibility of the pressure-sensitive adhesive in water decreases, and if the acid value is too high, water resistance and moisture resistance decrease, which is not preferable. These copolymer resins are, for example, SMA1
000, SMA2000, SMA3000, SMA14
40 and SMA17352 (trade name: manufactured by ATOFINA), and are readily available.

The acrylic copolymer which is suitably used as the resin constituting the component (A) of the present invention is (a-
1) 6 to 50% by weight of a polymerizable unsaturated carboxylic acid, and (a)
-2) A copolymer obtained by copolymerizing 94 to 50% by weight of another polymerizable monomer (provided that at least one of (a-1) and (a-2) is an acrylic monomer) Body.) The acid value of the acrylic copolymer is 100 to 500.
mgKOH / g is preferred, and more preferably 150 mgKOH / g.
３００300 mg KOH / g. If the acid value is too low, the redispersibility of the pressure-sensitive adhesive in water decreases, and if the acid value is too high, water resistance and moisture resistance decrease, which is not preferable.

(A-1) As the polymerizable unsaturated carboxylic acid, (meth) acrylic acid, maleic acid, itaconic acid, 2-carboxyethyl acrylate, (meth) acryloyloxyethyl succinic acid and the like can be used. it can. Among them, (meth) acrylic acid is preferred. These copolymers are not only neutralized by a low-volatility basic compound and impart water re-dispersibility to the adhesive but also impart cohesive force to the adhesive. At least 6% by weight of the polymerizable monomer having a group is required in the copolymer as the component (A). However, if the proportion of the polymerizable monomer having an acid group, for example, (meth) acrylic acid in the copolymer is too large, the water solubility of the pressure-sensitive adhesive increases, leading to wastewater contamination during repulping. Further, the tackiness of the copolymer may be reduced, or the viscosity of the pressure-sensitive adhesive may be increased, so that the polymerization stability may be lowered. Therefore the content ratio is 50
% By weight or less, more preferably 1% by weight.
5 to 40% by weight.

(A-2); Other copolymerizable monomers copolymerizable with the polymerizable monomer (a-1) having an acid group include, specifically, (meth) acrylic acid Methyl, ethyl (meth) acrylate, butyl (meth) acrylate,
(Meth) alkyl acrylates such as octyl (meth) acrylate, vinyl esters such as vinyl acetate, styrene, 2-hydroxyethyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate,
2-hydroxyethyl (meth) acrylate caprolactone adduct, (meth) acrylic acid ethylene oxide adduct, (meth) acrylic acid propylene oxide adduct and other hydroxyl group-containing (meth) acrylates, acrylonitrile, etc. Vinyl cyanide monomer, (meth) acrylamide, N-methylolacrylamide, styrenesulfonic acid, 2-acrylamide-2
-Methylpropanesulfonic acid, glycidyl methacrylate and the like. Of these, styrene and (meth)
It is preferred to use a hydrophobic monomer such as an alkyl acrylate. These monomers can be used alone or in combination of two or more kinds.
0% by weight, more preferably 85 to 85% by weight.
60% by weight.

The above acrylic copolymer is synthesized by a known emulsion polymerization method, solution polymerization, suspension polymerization method or the like. In that case, you may add a chain transfer agent as needed in order to adjust a molecular weight. As a chain transfer agent added at the time of copolymerization, alkyl mercaptans such as octyl mercaptan and lauryl mercaptan, thioglycolic acid esters such as butyl thioglycolate and octyl thioglycolate, and the like can be used. The amount added is 0.01 to 10 parts by weight, preferably 1 to 8 parts by weight, per 100 parts by weight of the monomer [(a-1) + (a-2)] constituting the copolymer. is there. In addition, the acrylic copolymer is a commercially available product having a name such as Joncryl 678, 680, 682 (trade name: manufactured by Johnson Polymer Co., Ltd.), and can be easily obtained from these products.

The carboxyl groups in the obtained copolymer are neutralized by adding a low volatile basic compound. The time of the neutralization reaction may be before or after the polymerization reaction, but the polymerization reaction is performed in order to homogenize the copolymer composition of the monomer containing a carboxyl group or the like and other copolymerization components. It is preferred to add it later.

In the present invention, the resin constituting the component (A) is neutralized with a low-volatile basic compound, that is, an alkali metal compound or an amino alcohol. Examples of the alkali metal compound include alkali metal hydroxides such as lithium, sodium, and potassium, among which sodium hydroxide is preferable. As amino alcohol, normal pressure (760
Amino alcohols having a boiling point of 120 ° C. or higher in mmHg) are preferred. Specifically, triethanolamine (boiling point: 360 ° C.), triisopropanolamine (boiling point:
307 ° C) 2-amino-2-methyl-1-propanol (boiling point: 165 ° C), N, N, dimethylethanolamine (boiling point: 135 ° C), N-methyldiethanolamine (boiling point: 246 ° C), etc. And amines having 1 to 3 hydroxyl groups. Among these, amino alcohols having three hydroxyl groups in one molecule and having a boiling point of 200 ° C. or higher at normal pressure and at normal pressure are preferable, and triethanolamine is particularly preferable.

One or more compounds selected from these alkali metal compounds and amino alcohols are added to the aqueous dispersion of the copolymer resin constituting the component (A) of the present invention in an aqueous dispersion of the copolymer. An acid group, for example, an amount corresponding to 50 to 120 mol% of a carboxyl group is added. If the amount is less than 50 mol%, when the pressure-sensitive adhesive composition is used, the adhesion and water dispersibility of the pressure-sensitive adhesive film are insufficient, and a uniform aqueous emulsion is not formed. Bleeding may occur, which may cause the adhesive paper to change over time. A more preferred addition amount is 60 to 100 mol%.

When volatile compounds such as ammonia and low-boiling alkylamines are used in the neutralization reaction, there is a disadvantage that these compounds are volatilized and the water redispersibility of the pressure-sensitive adhesive is deteriorated. The use of an amino alcohol having a boiling point of 120 ° C. or higher as a neutralizing agent in the aqueous copolymer dispersion of the present invention exerts a function as a plasticizer of the copolymer, and the adhesive performance by volatilization over time is reduced. Little change. In addition, it is not only effective in preventing the water redispersibility of the pressure-sensitive adhesive film from changing with time during repulping, but also advantageous in balancing the adhesion performance, particularly the adhesion and cohesion.

Component (B): (b-1) having 4 to 12 carbon atoms
40 to 98.9% by weight of (meth) acrylic acid alkyl ester having an alkyl group of (b-2), 1 to 20% by weight of polymerizable unsaturated carboxylic acid, and (b-3) other copolymerizable monomer A copolymer (B) obtained by copolymerizing 0.1 to 40% by weight with [b-1) + (b-2) +
(B-3) = 100%], which is an essential component for expressing the adhesive strength of the pressure-sensitive adhesive composition of the present invention. This copolymer is obtained by copolymerizing three different radically polymerizable monomers (b-1) to (b-3) described below. (B-1): Specific examples of the alkyl (meth) acrylate having an alkyl group having 4 to 12 carbon atoms include n-butyl acrylate, 2-ethylhexyl acrylate, and n-acrylic acid. Octyl, methacrylic acid-
2-Ethylhexyl, lauryl methacrylate and the like are preferable, and among them, n-butyl acrylate, 2-ethylhexyl acrylate, and n-octyl acrylate are preferable. The component (b-1) is a component for imparting adhesive strength to the copolymer, requires at least 40% by weight of the copolymer, and is used in the range of 40 to 98.9% by weight. If it is less than 40% by weight, sufficient adhesive strength cannot be obtained,
A more preferred range is 60 to 80% by weight.

(B-2): As the polymerizable unsaturated carboxylic acid, (meth) acrylic acid, maleic acid, itaconic acid and the like can be used. Especially preferred is (meta)
Acrylic acid. These are not only neutralized by a basic compound and impart water redispersibility to the pressure-sensitive adhesive, but also impart cohesive force to the pressure-sensitive adhesive, and at least 1% by weight of the copolymer is required. It is used in the range of -20% by weight. However, if the copolymerization ratio of (meth) acrylic acid exceeds 20% by weight, the water solubility of the pressure-sensitive adhesive increases, leading to wastewater contamination during repulping, and the tackiness of the copolymer decreases. In addition, the viscosity of the pressure-sensitive adhesive may increase and the polymerization stability may decrease, which is not preferable. A more preferred range is 2 to 10% by weight.

(B-3): Other copolymerizable monomers include (meth) such as methyl acrylate, ethyl acrylate, methyl methacrylate, and ethyl methacrylate.
Lower alkyl alkyl acrylate, methoxyethyl acrylate, methoxypropyl acrylate, ethoxyethyl acrylate, ethoxypropyl acrylate, methoxyethyl methacrylate, ethoxyethyl methacrylate, etc. Vinyl ester, styrene, 2-hydroxyethyl (meth) acrylate, (meth) acrylic acid-
4-hydroxybutyl or (meth) acrylic acid 2
-Caprolactone adduct of hydroxyethyl, (meth)
Hydroxyl group-containing (meth) acrylates such as ethylene oxide adducts of acrylic acid, propylene oxide adducts of (meth) acrylic acid, vinyl cyanide monomers such as acrylonitrile, (meth) acrylamide, N-methylolacrylamide, methacrylic acid Glycidyl, styrenesulfonic acid and the like can be mentioned. These monomers may be used alone or in combination of two or more,
0.1 to 40% by weight can be used. Among them, copolymerization of alkoxyalkyl (meth) acrylate such as methoxyethyl acrylate with 2 to 20% by weight, preferably 4 to 10% by weight improves the adhesive properties and water redispersibility of the copolymer. Therefore, it is preferable.

The copolymer as the component (B) can be produced by a known emulsion polymerization method, or after solution polymerization, the solvent can be distilled off under reduced pressure and water can be added to make the copolymer aqueous. Among them, the above-mentioned component (A) is used as a polymer surfactant, and the polymerizable monomers (b-1) to (b-3) are emulsified in the presence of a water-soluble resin as the component (A). It is preferable to produce the component (B) by polymerization. In that case, you may add a chain transfer agent, a pH adjuster, etc. as needed. The carboxyl group in the obtained copolymer is neutralized by a basic compound such as ammonia or amine. In this case, in order to improve the adhesive properties and redispersibility, it is preferable to neutralize the component (A) by adding the alkali metal compound or amino alcohol used when neutralizing the component, especially triethanolamine. The neutralization reaction may be performed before or after the polymerization reaction, but may be performed after the polymerization reaction to homogenize the copolymer composition of the carboxyl group-containing monomer and other copolymer components. preferable.

In preparing the pressure-sensitive adhesive composition of the present invention, the water-soluble resin of the component (A) may be separately added after the polymerization of the component (B).
It is preferable to use a dispersion of the component (B) produced by emulsion polymerization in the presence of the component (A), using the component as a polymeric surfactant. The ratio of the component (A) to the component (B) is in the range of (A) / (B) = 5/95 to 40/60 by weight, and preferably (A) / (B) = 6/94 to 30. / 7
0. In the present invention, the weight ratio [(A) / (B)] between the component (A) and the component (B) is based on the components (A) and (B) before each neutralization. If the amount of the component (A) is too small, the redispersibility in water is reduced. If the amount is too large, the physical properties of the pressure-sensitive adhesive such as tack and adhesive strength are undesirably reduced.

It is preferable to add a hydrophilic plasticizer (component (C)) to the pressure-sensitive adhesive composition of the present invention in order to improve tackiness such as tackiness and adhesive strength. As the hydrophilic plasticizer of the component (C), polyethylene glycol, polypropylene glycol, a nonionic surfactant or the like can be used. Above all, it is preferable to contain a nonionic surfactant having an HLB of 8 to 20. The addition of such a surfactant is effective not only in improving tack and adhesive strength, but also in facilitating redispersion of the pressure-sensitive adhesive film in the repulping step and reducing the size of dispersed particles. As a result, papermaking from recycled pulp does not show any trace of the original pressure-sensitive adhesive film.

As the nonionic surfactant, a water-soluble surfactant having an ethylene oxide chain at room temperature can be used. Examples thereof include ethers such as polyoxyethylene lauryl ether and polyoxyethylene stearyl ether; Alkyl phenol type such as polyoxyethylene nonyl phenyl ether and polyoxyethylene octyl phenyl ether; ester type such as polyoxyethylene monolaurate and polyoxyethylene monooleate; and polyoxyethylene sorbitan monolaurate and polyoxyethylene sorbitan monooleate And a nonionic surfactant such as a sorbitan ester ether type, etc., and these can be used alone or in combination of two or more. Components (A) and (B) of the present invention
To 30 parts by weight, more preferably 2 to 20 parts by weight, of these nonionic surfactants per 100 parts by weight of the copolymer. When the amount is less than 1 part by weight, the effect of improving the adhesive properties by adding a surfactant is small, and when the amount is more than 30 parts by weight, the adhesive properties are reduced, and bleeding to the base paper may occur.

The pressure-sensitive adhesive composition of the present invention contains a known tackifier, colorant, thickener, defoamer, and the like when preparing an aqueous emulsion for the purpose of enhancing its performance and adjusting its properties. A leveling agent or the like can be appropriately added. Further, other adhesive emulsions such as an ethylene-vinyl acetate-acrylic copolymer emulsion and a styrene-butadiene copolymer latex may be added as long as the water redispersibility of the present invention is not impaired.

As described above, the pressure-sensitive adhesive composition having redispersibility in water of the present invention has excellent pressure-sensitive adhesive properties, and when these are used for tack paper or pressure-sensitive adhesive tape, etc. It is an adhesive that can be easily disintegrated in water. The adhesive is redispersed and retained in the pulp instead of flowing out into the wastewater as in the prior art, so that it has the feature that recycled paper can be manufactured without deteriorating the quality of the wastewater.

[0032]

EXAMPLES The present invention will be described in more detail with reference to the following Examples, which, however, are not intended to limit the scope of the invention. In the following examples,
All parts and percentages are by weight. Abbreviations and their compounds are shown in the following table.

[Table 1]

In the present invention, the molecular weight of the resin of the component (A) is determined by GPC (gel permeation.
The weight average molecular weight in terms of polystyrene resin measured by chromatography was used. Viscosity measurement is based on JIS K7
The measurement was carried out at 25 ° C. using a Brookfield viscometer {manufactured by Tokimec Co., Ltd.} in accordance with 117.

Production Example 1 A styrene-maleic acid copolymer (SMA1000) was placed in a reaction vessel equipped with a dropping funnel, a condenser, and a stirrer.
25% aqueous solution of sodium salt (108 parts; breakdown SMA1000
20 parts, sodium hydroxide 6.8 parts, water 81 parts), JS
After adding -2 (2.5 parts) and distilled water (46 parts) and replacing the inside of the reaction system with nitrogen, the temperature in the system was adjusted to 75 ° C. After adding APS (0.8 parts) to this solution, 2-ethylhexyl acrylate (2-EHA; 152
Parts), methoxyethyl acrylate (MeEA; 20)
Parts), methyl methacrylate (MMA; 20 parts), methacrylic acid (MAA; 8 parts), 100 parts of water and JS-2
(2.5 parts) was added dropwise over 3 hours. After completion of the dropwise addition, the mixture was further aged at 75 ° C. for 2 hours, neutralized by dropwise addition of triethanolamine (TEA; 11 parts) and distilled water (11 parts), and having a viscosity of 110 mPa ·
s, a copolymer aqueous dispersion (emulsion) having a solid content of 49.1% was obtained.

Production Examples 2 to 5 (A) The component resin and the neutralizing agent were changed as shown in Table 1,
Otherwise, a copolymer aqueous dispersion was obtained according to the method of Production Example 1. In Production Example 5, emulsion polymerization was carried out using only the component (B).

[0036]

[Table 2]

Production Example 6 JS-2 (2.5 parts) and distilled water (150 parts) were charged into a reaction vessel equipped with a dropping funnel, a condenser and a stirrer, and the inside of the reaction system was replaced with nitrogen. The temperature of 75
Adjusted to ° C. After adding APS (1.0 part) to this solution, styrene (St; 6 parts), methyl methacrylate (MMA; 18 parts), acrylic acid (AA; 6 parts) and butyl thioglycolate (BTG; 1.2 parts) was added dropwise over 1 hour. After dropping, continue 7
After maintaining at 5 ° C. for 1 hour, a 25% aqueous sodium hydroxide solution (13.3 parts) was added dropwise to neutralize. Thereafter, a catalyst (APS) was added, and 2-ethylhexyl acrylate (2-EHA; 152 parts), methoxyethyl acrylate (MeEA; 20 parts), and methyl methacrylate (MMA;
20 parts), acrylic acid (AA; 8 parts), water (60 parts) and JS-2 (2.5 parts) were pre-emulsified and added dropwise over 2 hours. After dropping, 75 ° C
For 2 hours, and triethanolamine (TEA; 1)
(3.2 parts) and distilled water (13.2 parts) were added dropwise to neutralize to obtain an aqueous dispersion of a copolymer having a viscosity of 130 mPa · s and a solid content of 50.13%.

Production Examples 7 to 14 (A) Aqueous copolymer dispersion (emulsion) according to the method of Production Example 6, except that the monomer composition of the component resin and the neutralizing agent were changed as shown in Table 2. I got

[0039]

[Table 3]

Examples 1 to 14 and Comparative Examples 1 to 2 The surfactants shown in Table 3 were added to the aqueous dispersions of the copolymers obtained in Production Examples 1 to 14 to prepare pressure-sensitive adhesive compositions. The physical properties were evaluated by the following methods. The results are shown in Table 3. In Production Examples 5 and 14, the viscosity increased and gelled during the polymerization, and a good emulsion was not obtained. Regarding Production Example 12, aggregates were generated during the polymerization, but the aggregates were removed by filtration using a 120-mesh wire net, and evaluation was performed.

[0041]

[Table 4]

The test methods for evaluating the physical properties of the pressure-sensitive adhesive compositions obtained in Examples and Comparative Examples are as follows. The base material of the tack paper used in this test was a commercial kraft paper (with a basis weight of 7).
0 g / m ² ) and the amount of the adhesive composition applied was 25 g-dry / m ²
And dried at 120 ° C. for 1 minute. Keep this sample at 40 ° C
For one day after curing.

Test Method for Adhesive Property Adhesive force: A test piece was cut to a width of 25 mm, the release paper was peeled off, and then pressed on a polished SUS plate using a pressure bonding apparatus specified in JIS Z-0237, and then pressed.゜ Peel adhesion was measured. However, the pulling speed is 300mm /
Performed in minutes. Ball tack: J.B. described in JIS Z0237.
The ball tack at a tilt angle of 30 degrees and a measurement temperature of 23 ° C. was measured by the DOW method. The numbers represent ball numbers. Water redispersibility: The behavior of the pressure-sensitive adhesive when the surface of the pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet was rubbed with a finger while immersed in water at 25 ° C. was evaluated according to the following evaluation criteria. ：: The pressure-sensitive adhesive layer was redispersed into fine particles having no tackiness. Δ: The adhesiveness of the adhesive layer is reduced, but the adhesive layer is not finely dispersed or aggregated. X: The adhesiveness of the adhesive layer was not changed, and the adhesive layer film was aggregated.

[0044]

The pressure-sensitive adhesive composition of the present invention comprises, as main components, a water-soluble resin obtained by neutralizing a resin having a specific acid value and a molecular weight with a non-volatile basic compound, and an acrylic copolymer. It is obtained by adding a hydrophilic plasticizer such as an ionic surfactant, and has excellent tackiness and water redispersibility. Therefore, when the tack paper or the adhesive tape using the adhesive composition is repulped, it can be easily disintegrated in water and has excellent adhesive properties. The pressure-sensitive adhesive in the waste paper is redispersed to a size that cannot be observed with the naked eye during pulping, and is made together with the pulp.

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) C09J 201/08 C09J 201/08 G09F 3/10 G09F 3/10 A (72) Inventor Toshiya Seko Yokkaichi, Mie Prefecture 1 Toho-cho, Yokohama-shi F-term in Yokkaichi Office of Mitsubishi Chemical Corporation (Reference) 4J004 AA02 AA06 AA10 AA11 AA17 AB01 CB02 FA08 4J040 DA072 DA082 DB022 DB092 DD002 DF041 DF042 DF051 DF052 DF062 DF082 DF082 DF1022 DF1022 JA09 JB09 KA31 KA38 LA01 LA06 LA07

Claims (8)

[Claims] 1. A water-soluble resin (A) obtained by neutralizing a resin having an acid value of 60 mg KOH / g or more and a weight average molecular weight of 1,000 to 50,000 with an alkali metal compound or amino alcohol, and (b-1) 4-1 carbon number
(B) a polymerizable unsaturated carboxylic acid, 1 to 20% by weight, and (b-3) another copolymerizable compound. A copolymer (B) obtained by copolymerizing 0.1 to 40% by weight of a monomer [however, (b-1) + (b-2)
+ (B-3) = 100%], and the weight ratio of the water-soluble resin (A) to the copolymer (B) is (A) / (B) = 5.
/ 95 to 40/60. 2. The pressure-sensitive adhesive composition according to claim 1, wherein the resin constituting the water-soluble resin (A) is a styrene-maleic acid copolymer represented by the following general formula (1). object. Embedded image (Wherein m = 1 to 5, n = 5 to 20, R ₁ and R ₂ are each independently a hydrogen atom or an alkyl group having 1 to 18 carbon atoms (provided that at least _one of R ₁ and R ₂ is hydrogen) Represents an atom.) 3. The resin constituting the water-soluble resin (A) is an acrylic copolymer, which is composed of (a-1) 6 to 50% by weight of a polymerizable unsaturated carboxylic acid and (a- 2) Obtained by copolymerizing 94 to 50% by weight of another polymerizable monomer (provided that at least one of (a-1) and (a-2) is an acrylic monomer). The pressure-sensitive adhesive composition according to claim 1, wherein 4. An amino alcohol having a boiling point of 120 ° C. or higher is used.
The pressure-sensitive adhesive composition according to any one of claims 3 to 3. 5. The copolymer (B) comprises the water-soluble resin (A)
Wherein (b-1), (b-2) and (b-3) are emulsion-polymerized in the presence of (a).
The pressure-sensitive adhesive composition according to any one of the above. 6. A pressure-sensitive adhesive composition, wherein 1 to 30 parts by weight of a hydrophilic plasticizer (C) is added to 100 parts by weight of a water-soluble resin (A) and a copolymer (B) in the composition. The pressure-sensitive adhesive composition according to any one of claims 1 to 5, characterized in that: 7. The method according to claim 6, wherein the hydrophilic plasticizer (C) is a nonionic surfactant having an HLB of 8 to 20.
The pressure-sensitive adhesive composition according to item 1. 8. A pressure-sensitive adhesive tape or label comprising a pressure-sensitive adhesive layer containing the pressure-sensitive adhesive composition according to claim 1 on a substrate surface.