JP2000328031A - Aqueous adhesive composition - Google Patents

Abstract

(57) [Summary] [PROBLEMS] Conventionally, a step of desolvation is always required in the production of an aqueous urethane pressure-sensitive adhesive, and safety, production time, and cost have been problems. At the same time, it was not possible to easily obtain a water-based urethane pressure-sensitive adhesive having improved weather resistance and tackiness, which are disadvantages of the urethane pressure-sensitive adhesive. An object of the present invention is to provide an aqueous pressure-sensitive adhesive composition comprising an aqueous urethane pressure-sensitive adhesive which essentially does not require solvent removal in the production process and which overcomes the drawbacks of conventional urethane pressure-sensitive adhesives. SOLUTION: Instead of an organic solvent, a polyol and an organic polyisocyanate are reacted in an unsaturated monomer having no active hydrogen to obtain a polyurethane, which is then dispersed in water.
To provide an aqueous pressure-sensitive adhesive composition comprising an aqueous urethane composite resin which solves the above problems by polymerizing an unsaturated monomer solution of the polyurethane.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an aqueous pressure-sensitive adhesive composition comprising a radical polymer of urethane and an unsaturated monomer.

[0002]

2. Description of the Related Art Urethane adhesives have recently attracted attention because of their excellent removability and slight adhesiveness. conventionally,
It has been synthesized and used mainly with organic solvents such as toluene and ethyl acetate, but the use of these organic solvents poses a problem in terms of work environment safety and hygiene. To solve this, an aqueous urethane pressure-sensitive adhesive has also been developed. Although the aqueous urethane pressure-sensitive adhesive is superior to the conventional oil-based urethane pressure-sensitive adhesive in terms of use and handling, the use of an organic solvent in the production thereof and the removal of the solvent still cause environmental problems caused by the solvent. Further, in this method, problems such as the time and cost required for the solvent removal step, reuse of the organic solvent, incineration disposal, and the like have newly arisen.

Water-based urethane pressure-sensitive adhesives have properties which are not found in other acrylic pressure-sensitive adhesives and rubber-based pressure-sensitive adhesives as described above, but they are still insufficient from the viewpoint of versatility of use, and in particular, in terms of weather resistance. Inferior to other resins. As a method for compensating for these drawbacks, a method of adding a light stabilizer, an ultraviolet absorber, an antioxidant, and the like has been attempted, but is still insufficient.

[0004]

As described above, in the prior art, the step of removing the solvent is always required in the production of the aqueous urethane pressure-sensitive adhesive, and the time and cost required for the step are problematic. At the same time, it was not possible to easily obtain a water-based urethane pressure-sensitive adhesive having improved weather resistance and weak adhesion, which are disadvantages of the urethane pressure-sensitive adhesive. For these reasons, there has been a strong demand for an aqueous urethane pressure-sensitive adhesive which essentially does not require solvent removal in the production process and which overcomes the disadvantages of conventional urethane pressure-sensitive adhesives.

The present invention provides a water-based pressure-sensitive adhesive composition comprising a water-based urethane composite resin which is excellent in weather resistance and tackiness, which are disadvantages of conventional water-based urethane pressure-sensitive adhesives, and can be easily obtained without using a usual urethane synthesis solvent. It provides things.

[0006]

Means for Solving the Problems The present inventors have made intensive efforts to solve the above-mentioned problems, and as a result, they have no problems in environment, health and safety, and have excellent weather resistance and adhesiveness. An aqueous pressure-sensitive adhesive composition comprising a urethane composite resin has been obtained.

That is, the first invention is as follows: a) reacting a polyol with an organic polyisocyanate in an unsaturated monomer having no active hydrogen to obtain a number average molecular weight of 2
A polyurethane (A) having a glass transition temperature of -20 or less is synthesized.
A) a first step of obtaining an unsaturated monomer solution (B) adjusted to be lower than or equal to 0 ° C. or less; b) a second step of dispersing (B) in water to obtain an aqueous dispersion (C) of a polyurethane solution; An aqueous pressure-sensitive adhesive composition characterized by using an aqueous urethane composite resin (D) obtained from the third step of radically polymerizing (C).

The second invention is the aqueous pressure-sensitive adhesive composition according to the first invention, wherein the polyurethane (A) contains polyethylene glycol as an essential component in the first step.

The third invention is the aqueous pressure-sensitive adhesive composition according to the first invention, wherein the polyurethane (A) in the first step contains an ionizable polyol as an essential component.

A fourth invention is characterized in that in the first step, the polyurethane (A) is obtained by reacting a polyester polyol with a polyether polyol and an organic polyisocyanate in the presence of two kinds of catalysts. It is an aqueous pressure-sensitive adhesive composition according to the invention.

The fifth invention is characterized in that the polyurethane (A) accounts for 5% by weight to 80% by weight in the solid content of the aqueous urethane composite resin (D) obtained in the third step. Of the aqueous pressure-sensitive adhesive composition.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION In the production of an aqueous urethane composite resin, the reaction between a polyol and an organic polyisocyanate in an unsaturated monomer having no active hydrogen in the first step is carried out by previously converting the polyol into an unsaturated monomer. It is preferable that the polyisocyanate is added and dropped after being dissolved and dispersed therein. The method of dissolving and dispersing the polyol in the unsaturated monomer is as follows:
Alternatively, an operation of heating and stirring can be used. The heating is preferably performed at a lower temperature to prevent unnecessary polymerization of the unsaturated monomer, or under a purge with dry air and / or in the presence of a trace amount of a polymerization inhibitor.

Examples of the unsaturated monomer having no active hydrogen include unsaturated monomers containing no carboxyl group, hydroxyl group, methylol group, silanol group, primary or secondary amino group and the like. Examples include methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, isopropyl (meth) acrylate, butyl (meth) acrylate, pentyl (meth) acrylate, and (meth) Hexyl acrylate, 2-ethylhexyl (meth) acrylate, octyl (meth) acrylate, nonyl methacrylate, lauryl (meth) acrylate, methoxyethyl (meth) acrylate, methoxybutyl (meth) acrylate, (meth) acrylate (Meth) such as ethoxybutyl acrylate
Alkyl acrylate; unsaturated monomer having an epoxy group such as glycidyl (meth) acrylate, allyl glycidyl ether; acrylamide, N-butoxymethyl (meth) acrylamide, N-methylacrylamide, N, N-dimethylacrylamide, N An unsaturated monomer having an amide group such as isopropylacrylamide;
N, N-dimethylaminoethyl methacrylate, N, N
(Meth) acrylic acid having a tertiary amino group such as -diethylaminoethyl methacrylate, N, N-dimethylaminopropyl methacrylate; N-vinylpyrrolidone, N
-Nitrogen-containing unsaturated monomers such as vinylimidazole and N-vinylcarbazole; alicyclic (meth) acrylates such as cyclopentyl (meth) acrylate, cyclohexyl (meth) acrylate and isobornyl (meth) acrylate; styrene, α-methyl Aromatic unsaturated monomers such as styrene and phenyl methacrylate; silicon-containing unsaturated monomers such as vinyltriethoxysilane and γ-methacryloyloxypropyltrimethoxysilane; octafluoropentyl (meth) acrylate, perfluorocyclohexyl ( There are monomers having one unsaturated group, such as a fluorinated unsaturated monomer such as meth) acrylate and an unsaturated monomer in which an isocyanate group is blocked. Examples of the unsaturated monomer having no active hydrogen and having two unsaturated groups include divinylbenzene and polyethylene glycol di (meth) acrylate.

By selecting these unsaturated monomers having no active hydrogen, the urethanization reaction can be carried out as designed. It is desirable that these monomers dissolve the polyol and the polyisocyanate well, but it is also possible to select a system that does not completely dissolve as the reaction proceeds. If the solubility is poor, a monomer having high solubility in urethane resin such as vinylpyrrolidone, or a monomer relatively soluble in urethane such as aromatic unsaturated monomer is used. It is preferred to use.

When synthesizing the polyurethane in the first step, it is necessary that the unsaturated monomer does not contain active hydrogen, but after obtaining the polyurethane, the unsaturated monomer containing active hydrogen is added. May be. However, in order to obtain physical properties as a composite pressure-sensitive adhesive, it is necessary that the glass transition temperature of the unsaturated monomer copolymer after addition of the unsaturated monomer be -20 ° C or lower. The glass transition temperature mentioned here is obtained by multiplying the reciprocal of the glass transition temperature (absolute temperature) of a homopolymer of each unsaturated monomer, which is a usual calculation method, by the weight fraction of the unsaturated monomer. It can be obtained from the equation of adding the above for each unsaturated monomer. Examples of the unsaturated monomer that forms the skeleton according to the above formula include 2-ethylhexyl acrylate and butyl acrylate.

The unsaturated monomers having active hydrogen include:
Unsaturated monomers having a carboxyl group such as (meth) acrylic acid, itaconic acid and crotonic acid; 2-hydroxyethyl (meth) acrylate, hydroxypropyl (meth)
(Meth) acrylic esters having a hydroxyl group such as acrylate and 4-hydroxybutyl acrylate; and N-methylol (meth) acrylamide.

These unsaturated monomers having active hydrogen reduce the solution viscosity, and if the polyurethane has an NCO group at the end of urethane, a part of the unsaturated monomer having active hydrogen may have an urethane chain terminal. It reacts and can be complexed with other unsaturated monomers through a chemical bond in a later step. In addition, it becomes a crosslinking point when the polyfunctional compound is added, so that the adhesive strength can be controlled. If the polyurethane has a hydroxyl group or the like, an unsaturated monomer having an isocyanate group can be reacted after the synthesis of the polyurethane to add an unsaturated group to the polyurethane. Examples of unsaturated monomers having an isocyanate group include Karenz MOI (manufactured by Showa Denko KK) and MAI (manufactured by Nippon Paint Co., Ltd.)
Etc.

The polyol used in the first step preferably has two or more hydroxyl groups in one molecule. For example, low-molecular-weight polyols include dihydric alcohols such as ethylene glycol, diethylene glycol, trimethylene glycol, triethylene glycol, propylene glycol, butylene glycol, hexamethylene glycol, and neopentyl glycol.
And trihydric alcohols such as trimethylolethane, trimethylolpropane, and glycerin.

The high molecular weight polyol includes polyether polyol, polyester polyol, acrylic polyol, epoxy polyol and the like. Examples of the polyether polyol include polyethylene glycol, polyoxypropylene glycol, poly (ethylene / propylene) glycol, polytetramethylene glycol, and the like. Polyester polyols are obtained from the polycondensation of diols and dibasic acids. As the diol, besides the above-mentioned ethylene glycol and diethylene glycol, dipropylene glycol, 1,4-butanediol, 1,6-hexanediol, neopentyl glycol, and as the dibasic acid, adipic acid, azelaic acid, sebacic acid, isophthalic acid Acid and terephthalic acid. In addition, there are lactone ring-opening polymer polyols such as polycaprolactone and poly β-methyl-δ-valerolactone, and polycarbonate diol. Examples of the acrylic polyol include a copolymer of a monomer having a hydroxyl group. Hydroxyl group-containing monomers include hydroxyethyl (meth) acrylate, hydroxypropyl (meth) acrylate, hydroxybutyl acrylate, and dihydroxy acrylate, and epoxy polyols include amine-modified epoxy resins. Other examples include polybutadiene diol and castor oil.

These polyols can be used alone or in combination. It is appropriately selected in consideration of adhesiveness to an adherend, removability, holding power, and the like. When a polyester polyol and a polyether polyol are used in combination, a pressure-sensitive adhesive having good balance of tackiness and removability can be obtained. In particular, when a trifunctional polyol is partially used as a polyol component, there is no adhesive residue, and the pressure-sensitive adhesive has excellent cohesive strength.

It is necessary to select a polyol also from the viewpoint of solubility in unsaturated monomers having no active hydrogen and urethanization reaction. When polyethylene glycol is used alone or in combination with other diols as the diol, or when an ionizable polyol is used, water-solubilization is facilitated and a stable dispersion or hydrosol can be obtained.

An ionizable group as a polyol component,
For example, when a polyol having a carboxyl group, a sulfone group or the like is used, a self-emulsifiable polyurethane can be obtained. Examples of the carboxyl group-containing polyol include dimethylolpropionic acid, 2,2-dimethylolacetic acid, 2,2-dimethylolbutyric acid, dimethylolalkanoic acid such as 2,2-dimethylolpentanoic acid and dihydroxypropionic acid, dihydroxysuccinic acid, and dihydroxybenzoic acid. Acids. Particularly, dimethylolpropionic acid and 2,2-dimethylolbutyric acid are preferred from the viewpoint of reactivity and solubility.

As the organic polyisocyanate, there are aromatic, aliphatic and alicyclic polyisocyanates. For example, 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, m-phenylene diisocyanate, p-phenylene diisocyanate, 4,4'-diphenylmethane diisocyanate, tetramethylene diisocyanate, hexamethylene diisocyanate, xylylene diisocyanate, lysine diisocyanate , Isophorone diisocyanate, trimethylhexamethylene diisocyanate, 1,4-cyclohexylene diisocyanate, 4,4'-dicyclohexylmethane diisocyanate, 3,3'-dimethyl-4,4'-biphenylene diisocyanate, 3,3'-dimethoxy-4, 4'-
Buphenylene diisocyanate, 3,3'-dichloro-4,4'-biphenylene diisocyanate, 1,5-naphthalene diisocyanate, 1,5-tetrahydronaphthalene diisocyanate and the like can be used alone or in a mixture.

As the catalyst used in the present invention, a known catalyst can be used. For example, tertiary amine compounds, organometallic compounds and the like can be mentioned.

Examples of the tertiary amine compound include triethylamine, triethylenediamine, 1,8-diazabicyclo (5,4,0) -undecene-7 (DBU) and the like.

The organometallic compounds include tin compounds and non-tin compounds.

As the tin-based compound, dibutyltin dichloride, dibutyltin oxide, dibutyltin dibromide,
Dibutyltin dimaleate, dibutyltin dilaurate (D
BTDL), dibutyltin diacetate, dibutyltin sulfide, tributyltin sulfide, tributyltin oxide, tributyltin acetate, triethyltin ethoxide, tributyltin ethoxide, dioctyltin oxide, tributyltin chloride, tributyltin trichloroacetate, 2-ethylhexanoic acid Tin etc. are mentioned.

Examples of the non-tin compounds include titanium compounds such as dibutyl titanium dichloride, tetrabutyl titanate and butoxy titanium trichloride, and lead compounds such as lead oleate, lead 2-ethylhexanoate, lead benzoate and lead naphthenate. Iron, such as iron, 2-ethylhexanoate and iron acetylacetonate; cobalt, such as cobalt benzoate and cobalt 2-ethylhexanoate; zinc, such as zinc naphthenate and zinc 2-ethylhexanoate; zirconium naphthenate And the like.

When a urethane resin is synthesized from a polyol having good compatibility, a single catalyst can be used for uniform synthesis. However, in a system in which two types of polyols, a polyester polyol and a polyether polyol, are present, the reaction solution becomes turbid in a single catalyst system due to the difference in reactivity and compatibility. If present, the problem of gelation is likely to occur. At this time, by using two kinds of catalysts, the coordination property, the reaction rate and the like of the catalyst can be controlled, and these problems can be solved. As the combination, a tertiary amine / organic metal system, tin system / non-tin system, tin system / tin system, etc. are possible, but a tin system / tin system is more preferable, and dibutyltin dilaurate and 2-ethyl are more preferable. It is a combination of tin hexanoate. The compounding ratio is tin 2-ethylhexanoate / dibutyltin dilaurate <1 by weight. More preferably, 0.2 to 0.1.
6. If the compounding ratio is 1 or more, gelation is likely to occur due to the balance of the catalytic activity. These catalysts are used in an amount of 0.00 to the total amount of the polyol and the organic polyisocyanate.
5 to 1.0% by weight.

In order to obtain a urethane resin in an unsaturated monomer, various methods are possible. For example, 1) charging the whole amount,
2) A method in which a polyol and a catalyst are charged into a flask and an organic polyisocyanate is dropped. The method 2) is preferred for controlling the reaction.

The urethanization reaction is carried out in the presence of a catalyst at 60 to
It is preferably performed at 90 ° C. for 2 to 20 hours. More preferably, the temperature is from 70C to 85C. When the reaction temperature is 90 ° C. or higher, it is difficult to control the reaction rate and the crosslinked structure, it is difficult to obtain a urethane resin having a predetermined molecular weight, and the unsaturated monomer is easily polymerized. The end point of the reaction is determined by NCO% measurement and disappearance of NCO peak by IR measurement.

In the reaction in an unsaturated monomer, the solution viscosity generally becomes higher than that in a solvent system, so it is important to keep the molecular weight of the polyurethane within a specific range. When the number average molecular weight of the polyurethane is 20,000 or more, the viscosity increases significantly or the reaction requires a long time. When the ratio of the polyurethane to the total of the weight of the polyurethane and the weight of the unsaturated monomer is 80% by weight or more, the weather resistance and tackiness characteristic of the unsaturated monomer are reduced. It is difficult to develop characteristics such as removability.

The method of imparting water-solubility to the polyurethane in the second step is as follows: 1) a method of using a diol having a carboxyl group as a diol component and neutralizing with a base; and 2) an alkyl dialkanolamine having a tertiary amino group. 3) A method of prepolymerizing with an alkyl dialkanolamine having a tertiary amino group, neutralizing with an acid to form an amine salt, 4) a highly water-soluble polyol such as polyethylene Examples include a method in which glycol is used as a urethane component. These water-soluble urethane resins also serve to disperse unsaturated monomers.

For dispersion in water, a surfactant may be used. The surfactant is used for the purpose of improving the stability of the aqueous dispersion of the unsaturated monomer solution of the polyurethane or the polymerization stability and the stability over time of the composite resin dispersion obtained by polymerizing the dispersion. As the surfactant, any of nonionic, anionic and cationic surfactants can be used, but nonionic surfactants are particularly preferable from the viewpoint of emulsion stability, polymerization stability and stability over time. Examples of the nonionic activator include polyoxyethylene lauryl ether, polyoxyethylene cetyl ether, polyoxyethylene stearyl ether, polyoxyethylene alkyl ether such as polyoxyethylene oleyl ether; polyoxyethylene octyl phenyl ether, polyoxyethylene nonyl phenyl Ethers, polyoxyethylene alkylphenyl ethers such as polyoxyethylene dodecylphenyl ether; polyoxyethylene alkyl esters, polyoxyethylene alkylphenyl esters, etc., sorbitan monolaurate, sorbitan monopalmitate, sorbitan monostearate, sorbitan distearate Fatty acid esters such as sorbitan monooleate, sorbitan trioleate, etc., polyoxyethylene Nso sorbitan monolaurate, polyoxyethylene sorbitan monopalmitate, there polyoxyethylene sorbitan monostearate, polyoxyethylene sorbitan fatty acid esters such as polyoxyethylene sorbitan monooleate and the like. Examples of the anionic property include an alkyl sulfate, an alkylbenzene sulfonate, a naphthalene sulfonate, and an alkyl sulfosuccinate.

When a reactive activator having a radically polymerizable unsaturated group in the molecule is used in combination, it is possible to suppress a decrease in water resistance. Examples include alkylphenyl ethers (commercially available products, such as HS-10, HS-20, RN-20, and RN-30 manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd.),
There are sulfosuccinates (commercially available products such as Latemul S-120P and S-180A manufactured by Kao Corporation, Eleminor JS-2 manufactured by Sanyo Chemical Industries, Ltd.).

These surfactants are used alone or in a mixture. The amount used is preferably in the range of 0.1% by weight to 10% by weight with respect to the polyurethane and the unsaturated monomer.

The basic compound used for aqueous conversion includes sodium hydroxide, potassium hydroxide, ammonia,
Methylamine, ethylamine, propylamine, butylamine, hexylamine, octylamine, ethanolamine, propanolamine, diethanolamine, N
-Methyldiethanolamine, dimethylamine, diethylamine, triethylamine, N, N-dimethylethanolamine, 2-dimethylamino-2-methyl-1-propanol, 2-amino-2-methyl-1-propanol, morpholine and the like; , Used in mixing. When neutralizing the unsaturated monomer solution of the polyurethane, it is necessary to appropriately select a neutral compound because the compatibility with the solution and the stability after dispersion in water may differ depending on the type of the basic compound. In neutralizing a compound having a carboxyl group such as dimethylolalkanoic acid, the amount is preferably 0.6 to 1.2 equivalents per equivalent of the carboxyl group.

As a mechanical method for dispersing the unsaturated monomer solution of polyurethane in water, it is possible to disperse the unsaturated monomer solution in water with an ordinary stirrer. In order to obtain a stable aqueous dispersion, forcible dispersion under a high shearing force using a homomixer, a homogenizer, or a microfluidizer (manufactured by Mizuho Industry Co., Ltd.) is preferable.

In the second step, if necessary, a small amount of an organic solvent may be used in combination and dispersed in water.

In order to polymerize the aqueous dispersion in the third step to obtain a composite resin dispersion, a known radical polymerization method is preferable. As the polymerization initiator, both a water-soluble initiator and an oil-soluble initiator can be used. When using the oil-soluble initiator, it is preferable to dissolve it in advance in the unsaturated monomer solution of the polyurethane. These polymerization initiators are suitably used in the range of 0.01 to 5% with respect to the unsaturated monomer. Temperature is 4
0 ° C to 100 ° C is preferred, and 80 ° C for a redox initiator.
The following is sufficient. As the polymerization initiator, azobisisobutyronitrile, azobisisobutylvaleronitrile,
Azo compounds such as benzoyl peroxide, isobutyryl peroxide, octanoyl peroxide, cumylperoxy octate, t-butylperoxy-2-ethylhexanoate, t-butylperoxyacetate, lauryl peroxide, Organic peroxides such as t-butyl peroxide and di-2-ethylhexyl peroxyzine carbonate; and inorganic peroxide compounds such as potassium persulfate, ammonium persulfate and hydrogen peroxide. Organic or inorganic peroxide compounds can also be used as redox initiators in combination with reducing agents. Examples of the reducing agent to be used include L-ascorbic acid, L-sorbic acid, sodium metabisulfite, ferric sulfate, ferric chloride, Rongalit and the like.

As a method of polymerizing the aqueous dispersion of the unsaturated monomer solution of the polyurethane, a method of charging the whole amount, dripping the whole amount, or a method of partially charging the remaining portion is possible. In the polymerization of the unsaturated monomer, a known chain transfer agent for the purpose of adjusting the molecular weight, for example, octyl mercaptan, lauryl mercaptan, 2-mercaptoethanol, terchardodecyl mercaptan, thioglycolic acid, or the like can be used. is there.

In the present invention, it is possible to adjust the adhesive strength and cohesive strength by blending a polyfunctional compound. Examples of the polyfunctional compound include an isocyanate compound, a blocked isocyanate compound, an oxazoline compound, a carbodiimide compound, an aziridine compound, and an epoxy compound. In particular, when a polyfunctional isocyanate compound is added, the resulting adhesive is excellent in adhesive strength, cohesive strength, adhesive residue, and pot life. As the polyfunctional isocyanate compound, the above-mentioned organic polyisocyanate compounds and their trimethylolpropane adducts, burettes reacted with water, trimers having an isocyanurate ring, and the like are used. The compounding ratio is 100 parts (parts by weight) of the solid content of the composite resin.
1 to 20 parts is used. If it is 1 part or less, the cohesive strength decreases, and if it is 20 parts or more, the adhesive strength decreases. Preferably it is 2 to 10 parts.

In the pressure-sensitive adhesive composition of the present invention, other resins such as acrylic resin, polyester resin, amino resin, polyurethane resin, epoxy resin and the like may be used in combination, if necessary. It is possible to appropriately add a tackifier, a coloring agent, an ultraviolet absorber, a light stabilizer, and an organic solvent.

The aqueous pressure-sensitive adhesive composition containing the aqueous urethane composite resin thus obtained is used for paper, plastics, for display, for surface protection, for non-slip, and for temporary application.
It can be widely used for adherends such as metals and textiles. The aqueous urethane composite resin which is a feature of the present invention is obtained by the following synthesis examples.

Synthesis Example 1 80 g of butyl acrylate, 15 g of methyl methacrylate, polyether polyol PP-2000 were placed in a three-necked flask equipped with a stirrer, a reflux condenser, a gas inlet tube and a thermometer.
79 g (bifunctional, OH value 56, manufactured by Sanyo Chemical Co., Ltd.)
7 g of dimethylolbutanoic acid, 14 g of hexamethylene diisocyanate (manufactured by Sumitomo Bayer Co., Ltd.), and 0.05 g of tin 2-ethylhexanoate were charged as a catalyst, and the temperature was gradually raised to 80 ° C. in an air atmosphere, followed by a reaction for 4 hours. . The number average molecular weight of the polyurethane was 18,000.

After cooling to room temperature, 5 g of 2-hydroxyethyl acrylate (calculated glass transition temperature of copolymer-
29 ° C.), 0.5 g of azobisisobutyronitrile, 2 g of reactive activator HS-10 (manufactured by Daiichi Kogyo Seiyaku Co., Ltd.), and after stirring well, 4 g of ammonia water and 300 g of distilled water are further added. Then, an unsaturated monomer solution of polyurethane was dispersed in water.

Next, the temperature of the aqueous dispersion was raised to 85 ° C. in a nitrogen atmosphere, and radical polymerization of the unsaturated monomer was performed for 5 hours. The aqueous urethane composite resin thus obtained has MN (number average molecular weight) of 21,000 and MW (weight average molecular weight) of 4
6,000.

Synthesis Example 2 80 g of butyl acrylate, 15 g of methyl methacrylate, PP-2000 of polyether polyol were placed in a three-necked flask equipped with a stirrer, a reflux condenser, a gas inlet tube, and a thermometer.
73 g (bifunctional, OH value 56, manufactured by Sanyo Chemical Co., Ltd.)
Polyethylene glycol PEG-2000 (bifunctional, O
H value 56, manufactured by NOF Corporation, 7 g, dimethylolbutanoic acid, 7 g, isophorone diisocyanate (Hulls.
13 g of tin 2-ethylhexanoate as a catalyst and 80 ° C. in an air atmosphere.
The temperature was gradually raised until the reaction was completed for 4 hours. The number average molecular weight of the polyurethane was 13,000.

After cooling to room temperature, 5 g of 2-hydroxyethyl acrylate (calculated glass transition temperature of copolymer-
29 ° C.), 0.5 g of azobisisobutyronitrile was added, and the mixture was stirred well.
Then, the unsaturated monomer solution of polyurethane was dispersed in water.

Next, the temperature of the aqueous dispersion was raised to 85 ° C. in a nitrogen atmosphere, and radical polymerization of the unsaturated monomer was carried out for 5 hours. The aqueous urethane composite resin thus obtained had MN (number average molecular weight) of 19,000 and MW (weight average molecular weight) of 3
It was 7,000.

Synthesis Example 3 80 g of 2-ethylhexyl acrylate, 15 g of vinyl acetate, polyester polyol P-1 were placed in a three-necked flask equipped with a stirrer, a reflux condenser, a gas inlet tube and a thermometer.
010 (bifunctional, OH value 112, manufactured by Kuraray Co., Ltd.) 2
9 g, polyethylene glycol PEG-2000 (bifunctional, OH value 56, manufactured by NOF Corporation) 7 g, polyether polyol GP-3000B (trifunctional, molecular weight 30)
00, manufactured by Asahi Denka Co., Ltd.), 54 g of hexamethylene diisocyanate (manufactured by Sumitomo Bayer Co., Ltd.), 0.01 g of tin 2-ethylhexanoate, and 0.03 g of dibutyltin dilaurate as catalysts, and 80 g in an air atmosphere.
The temperature was gradually raised to 0 ° C., and the reaction was performed for 4 hours. The number average molecular weight of the polyurethane was 17,500.

After cooling to room temperature, 5 g of 2-hydroxyethyl acrylate (calculated glass transition temperature of copolymer-
44 ° C.), 0.5 g of azobisisobutyronitrile was added, and the mixture was stirred well.
2 g (manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) and 300 g of distilled water were added, and the polyurethane unsaturated monomer solution was dispersed in water.

Then, the temperature of the aqueous dispersion was raised to 85 ° C. in a nitrogen atmosphere, and radical polymerization of the unsaturated monomer was performed for 5 hours. The aqueous urethane composite resin thus obtained has MN (number average molecular weight) of 21,000 and MW (weight average molecular weight) of 4
It was 9,000.

Synthesis Example 4 40 g of 2-ethylhexyl acrylate, 7.5 g of vinyl acetate, polyether polyol PP were placed in a three-necked flask equipped with a stirrer, a reflux condenser, a gas introduction tube, and a thermometer.
-2000 (bifunctional, OH value 56, manufactured by Sanyo Chemical Co., Ltd.) 110 g, polyethylene glycol PEG-200
0 (bifunctional, OH value 56, manufactured by NOF Corporation) 10
g, 10 g of dimethylolbutanoic acid, 20 g of isophorone diisocyanate (manufactured by Huls Japan KK), and 0.075 g of tin 2-ethylhexanoate as a catalyst, and gradually heated to 80 ° C. in an air atmosphere, and reacted for 4 hours. I let it. The number average molecular weight of the polyurethane is 13,500
Met.

After cooling to room temperature, 2.5 g of 2-hydroxyethyl acrylate, 0.1 g of Karenz MOI (manufactured by Showa Denko KK), 0.25 g of azobisisobutyronitrile
After stirring well, 6 g of ammonia water and 300 g of distilled water were further added to disperse the unsaturated monomer solution of polyurethane in water (calculated glass transition temperature of copolymer-
44 ° C).

Next, the temperature of the aqueous dispersion was raised to 85 ° C. in a nitrogen atmosphere, and radical polymerization of the unsaturated monomer was performed for 5 hours. The aqueous urethane composite resin thus obtained has MN (number average molecular weight) of 12,000 and MW (weight average molecular weight) of 2
It was 9,000.

Synthesis Example 5 In a three-necked flask equipped with a stirrer, a reflux condenser, a gas inlet tube, and a thermometer, 144 g of 2-ethylhexyl acrylate was placed.
27 g of vinyl acetate, polyether polyol PP
-2000 (bifunctional, OH value 56, manufactured by Sanyo Chemical Co., Ltd.) 15 g, polyethylene glycol PEG-2000
(Bifunctional, OH value 56, manufactured by Nippon Oil & Fats Co., Ltd.) 1 g, dimethylolbutanoic acid 1 g, isophorone diisocyanate (manufactured by Huls Japan KK) 3 g, catalyst 2
0.01 g of tin ethylhexanoate was charged, and the temperature was gradually raised to 80 ° C. in an air atmosphere, followed by a reaction for 4 hours. The number average molecular weight of the polyurethane was 13,800.

After cooling to room temperature, 9 g of 2-hydroxyethyl acrylate (calculated glass transition temperature of copolymer-
44 ° C.), 0.9 g of azobisisobutyronitrile was added, and the mixture was stirred well.
Then, the unsaturated monomer solution of polyurethane was dispersed in water.

Next, the temperature of the aqueous dispersion was raised to 85 ° C. in a nitrogen atmosphere, and radical polymerization of the unsaturated monomer was carried out for 5 hours. The aqueous urethane composite resin thus obtained has MN (number average molecular weight) of 49,000 and MW (weight average molecular weight) of 7
It was 5,000.

Synthesis Example 6 65 g of butyl acrylate, 30 g of methyl methacrylate, polyether polyol PP-2000 were placed in a three-necked flask equipped with a stirrer, a reflux condenser, a gas inlet tube, and a thermometer.
(Bifunctional, OH value 56, manufactured by Sanyo Chemical Co., Ltd.) 77 g,
7 g of dimethylolbutanoic acid, 16 g of hexamethylene diisocyanate (manufactured by Sumitomo Bayer Co., Ltd.), and 0.05 g of tin 2-ethylhexanoate were charged as a catalyst, and the temperature was gradually raised to 80 ° C. in an air atmosphere, followed by a reaction for 4 hours. . The number average molecular weight of the polyurethane was 21,000.

After cooling to room temperature, 5 g of 2-hydroxyethyl acrylate (calculated glass transition temperature of copolymer-
13 ° C), 0.5 g of azobisisobutyronitrile, 2 g of reactive activator HS-10 (manufactured by Daiichi Kogyo Seiyaku Co., Ltd.), and after stirring well, 4 g of ammonia water and 300 g of distilled water are further added. Then, an unsaturated monomer solution of polyurethane was dispersed in water.

Next, the temperature of the aqueous dispersion was raised to 85 ° C. in a nitrogen atmosphere, and radical polymerization of the unsaturated monomer was performed for 5 hours. The aqueous urethane composite resin thus obtained has MN (number average molecular weight) of 29,000 and MW (weight average molecular weight) of 5
It was 7,000.

Synthesis Example 7 In a three-necked flask equipped with a stirrer, a reflux condenser, a gas inlet tube and a thermometer, 24 g of 2-ethylhexyl acrylate, 4.5 g of vinyl acetate, polyether polyol PP
-2000 (bifunctional, OH value 56, manufactured by Sanyo Chemical Co., Ltd.) 124 g, polyethylene glycol PEG-200
0 (bifunctional, OH value 56, manufactured by NOF Corporation) 12
g, 11 g of dimethylolbutanoic acid, 23 g of isophorone diisocyanate (manufactured by Huls Japan KK), and 0.08 g of tin 2-ethylhexanoate as a catalyst,
The temperature was gradually raised to 80 ° C. in an air atmosphere, and the reaction was performed for 4 hours. The number average molecular weight of the polyurethane was 13,000.

After cooling to room temperature, 1.5 g of 2-hydroxyethyl acrylate (calculated glass transition temperature as a copolymer -44 ° C.) and 0.2 g of azobisisobutyronitrile were added, and the mixture was stirred well. 6 g of ammonia water and 300 g of distilled water were added, and the unsaturated monomer solution of polyurethane was dispersed in water.

Next, the temperature of the aqueous dispersion was raised to 85 ° C. in a nitrogen atmosphere, and radical polymerization of the unsaturated monomer was carried out for 5 hours. The aqueous urethane composite resin thus obtained has MN (number average molecular weight) of 11,000 and MW (weight average molecular weight) of 2
It was 8,000.

Synthesis Example 8 Polyether polyol PP was placed in a four-necked flask equipped with a stirrer, a reflux condenser, a nitrogen inlet tube, a thermometer, and a dropping funnel.
2000 (bifunctional, OH value 56, manufactured by Sanyo Chemical Co., Ltd.)
228 g, polyester polyol P-2010 (bifunctional, OH value 56, manufactured by Kuraray Co., Ltd.) 228 g, trimethylolpropane 2 g, isophorone diisocyanate (manufactured by Huls Japan KK) 42 g, ethyl acetate 500 g, 2-ethylhexanoic acid as a catalyst 0.1 g of tin
Was gradually heated to 80 ° C., and reacted for 4 hours. MN (number average molecular weight) was 10,000 and MW (weight average molecular weight) was 32,000.

Synthesis Example 9 300 g of ethyl acetate was charged into a four-necked flask equipped with a stirrer, a reflux condenser, a nitrogen inlet tube, a thermometer, and a dropping funnel.
The temperature was raised to 80 ° C. Next, a mixture composed of 160 g of 2-ethylhexyl acrylate, 30 g of vinyl acetate, 10 g of 2-hydroxyethyl acrylate, and 1 g of benzoyl peroxide was added dropwise over 1 hour, and the mixture was further reacted for 4 hours.
MN (number average molecular weight) was 59,000 and MW (weight average molecular weight) was 264,000.

[0068]

EXAMPLES The present invention will be described in detail with reference to production examples and examples, but the present invention is not limited to these examples. In the following Production Examples and Examples, “parts” means parts by weight unless otherwise specified.

Table 1 shows the adhesive composition.

Table 2 shows the results of the adhesive strength, holding power, ball tack, removability and weather resistance test results.

The test items are as follows.

Coating method: The above-mentioned pressure-sensitive adhesive solution is applied to a release paper so that a dry coating film has a thickness of 25 μm, dried at 100 ° C. for 2 minutes, and a coated material is prepared using a PET sheet. 1 at room temperature
Aged for a week.

Adhesion: Adhesion sheet made of PET film base material is adhered to a stainless steel plate (SUS304) having a thickness of 2 mm at 23 ° C. and 65% RH, roll-pressed in accordance with JIS, and after 20 minutes, shopper type peeling. Peel strength (180 degree peel, tensile speed 300 mm / min) was measured with a tester.

Holding force: A pressure-sensitive adhesive sheet was adhered to a stainless steel plate (SUS304) having a thickness of 2 mm with an area of 25 mm × 25 mm and roll-pressed in accordance with JIS, and after being left at 40 ° C. for 20 minutes, a load of 1 kg was applied, and after 60 minutes. The deviation was measured.

Ball tack: J. It was measured under the conditions of 23 ° C. and 65% RH by the Dow rolling ball method.

Removability: After adhering the pressure-sensitive adhesive sheet, 40
C. for 1 day, peeled off, and visually evaluated for adhesive residue. After peeling, ◎ indicates no adhesive transfer to the adherend, ○ indicates very slight transfer, △ indicates partial transfer, and × indicates complete transfer.

Weather resistance: The composition obtained in the example was applied on a glass plate so as to have a thickness of 0.5 mm, and was formed into a film by a dryer at 60 ° C. to obtain a sample. Duplicate the sample
Irradiation was performed for 200 hours using a cycle-type weather meter, and the gloss was measured. The gloss retention was calculated by comparison with the initial gloss. A gloss retention of 80% or more was evaluated as ◎, 60 to 80% as ％, 40 to 60% as Δ, and 40% or less as X.

[0078]

[Table 1]

[0079]

[Table 2]

From the above results, it can be seen that the pressure-sensitive adhesive composition according to the present invention has good adhesive strength, removability and excellent weather resistance.

[0081]

The present invention is an aqueous pressure-sensitive adhesive which is excellent in cost, environmental safety and work safety since no solvent is used in the synthesis. In addition, in the production process, since the urethane reaction is performed in the unsaturated monomer, the urethane resin and the unsaturated monomer can be directly chemically bonded, and a resin form different from the blend system is used. Can be given. The urethane pressure-sensitive adhesive compounded with such an unsaturated monomer can improve physical properties such as weather resistance and adhesiveness, which are disadvantages of the urethane pressure-sensitive adhesive, without impairing the removability, which is an advantage of urethane. According to this method, it has become possible to provide a very practical aqueous pressure-sensitive adhesive composition.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) C09J 175/04 C09J 175/04 F-term (Reference) 4J011 JA13 JB02 JB07 JB14 JB21 JB26 JB27 4J026 AB02 AB03 AC33 BA05 BA07 BA16 BA20 BA25 BA27 BA29 BA30 BA32 BA34 BA40 BA43 BA50 BB07 CA02 DB03 DB04 DB08 DB09 DB10 DB12 DB14 DB15 DB16 DB22 DB26 GA08 GA09 4J040 DL151 JA03 JB09 LA01 LA02 LA06 LA07 QA01

Claims (5)

[Claims] 1. a) reacting a polyol with an organic polyisocyanate in an unsaturated monomer having no active hydrogen,
Polyurethane (A) having a number average molecular weight of 20,000 or less was synthesized, and an unsaturated monomer solution (B) adjusted so that the glass transition temperature of the copolymer of the unsaturated monomer was -20 ° C or less. B) aqueous dispersion of (B) to obtain an aqueous dispersion (C) of a polyurethane solution; c) aqueous urethane obtained from the third step of radically polymerizing (C). An aqueous pressure-sensitive adhesive composition using the composite resin (D). 2. The aqueous pressure-sensitive adhesive composition according to claim 1, wherein in the first step, the polyurethane (A) contains polyethylene glycol as an essential component. 3. The aqueous pressure-sensitive adhesive composition according to claim 1, wherein the polyurethane (A) comprises an ionizable polyol as an essential component in the first step. 4. The method according to claim 1, wherein the polyurethane (A) comprises:
The aqueous pressure-sensitive adhesive composition according to claim 1, which is obtained by reacting a polyester polyol, a polyether polyol, and an organic polyisocyanate in the presence of two types of catalysts. 5. The water-based pressure-sensitive adhesive according to claim 1, wherein the polyurethane (A) accounts for 5% to 80% by weight of the solid content of the aqueous urethane composite resin (D) obtained in the third step. Composition.