JP2001131511A - Water dispersion type pressure-sensitive adhesive composition and method for producing the same, and adhesive sheet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a water dispersion type pressure-sensitive adhesive composition which gives adhesive sheets which have excellent stability in the molecular weights of solvent insolubles and solvent solubles and in the terminal peeling resistance of the sheets with the passage of time. SOLUTION: This water dispersion type pressure-sensitive adhesive composition contains a polymer obtained by copolymerizing a monomer composition containing an alkyl (meth)acrylate as a main component and a silane-based monomer. The composition may be a water dispersion type pressure-sensitive adhesive composition which contains a polymer obtained by copolymerizing a monomer composition containing an alkyl (meth)acrylate as a main component and giving a resin composition having a solvent-insoluble content of <=5%, when polymerized in the state of a composition not containing a silane-based monomer, and the silane-based monomer in an amount of 0.005 to 1 pt.wt. per 100 pts.wt. of the monomer mixture under the same condition as above.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an acrylic water-dispersible pressure-sensitive adhesive (adhesive), a method for producing the same, and an adhesive sheet.

[0002]

2. Description of the Related Art A pressure-sensitive adhesive sheet using a water-dispersible acrylic pressure-sensitive adhesive does not use a solvent, and thus has advantages such as environmental hygiene and excellent solvent resistance.
Generally, this pressure-sensitive adhesive sheet is prepared by adding a cross-linking agent after completion of polymerization of a monomer mixture containing an acrylic monomer as a main component in order to adjust a solvent-insoluble component that affects the holding power of the pressure-sensitive adhesive layer and the like. It is manufactured by preparing a composition and applying it to a substrate. However, in the pressure-sensitive adhesive sheet thus obtained, the solvent-insoluble content of the pressure-sensitive adhesive constituting the pressure-sensitive adhesive layer and the molecular weight of the solvent-soluble portion of the pressure-sensitive adhesive change with time, and accordingly, the terminal peelability ( However, there is a problem that the end portion is hardly peeled off after the adherend is attached. Further, when compared with a pressure-sensitive adhesive sheet using a solvent-type pressure-sensitive adhesive, the pressure-sensitive adhesive sheet using the above-mentioned water-dispersed pressure-sensitive adhesive has a disadvantage that it is difficult to achieve both the performance of terminal peelability and the property of retention. Had.

[0003]

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a pressure-sensitive adhesive sheet having a water-dispersible pressure-sensitive composition having excellent solvent-insoluble content, molecular weight of a solvent-soluble portion, and excellent terminal peeling stability over time. An object of the present invention is to provide an adhesive composition, a method for producing the same, and a pressure-sensitive adhesive sheet having the above-mentioned excellent properties. Also,
Another object of the present invention is to provide a water-dispersed pressure-sensitive adhesive composition exhibiting excellent terminal peelability and holding properties equal to or better than that of a solvent-based pressure-sensitive adhesive, a method for producing the same, and a pressure-sensitive adhesive sheet having the above characteristics. Is to provide.

[0004]

Means for Solving the Problems The present inventors have conducted intensive studies to achieve the above object, and as a result, have found that a water-dispersible monomer mixture containing (meth) acrylic acid alkyl ester as a main component has a silane compound. It has been found that, when a polymerization is carried out by adding a system monomer and a chain transfer agent as needed, a pressure-sensitive adhesive composition having good stability over time in solvent-insoluble matter, molecular weight of a solvent-soluble portion and terminal peelability can be obtained. Was. In particular, a silane-based monomer is added at a specific ratio to a monomer mixture containing a (meth) alkyl acrylate as a main component such that the solvent-insoluble content of the polymer becomes a specific value or less. It has been found that, when copolymerized by the above method, excellent terminal peelability and high retention can be achieved at the same time even with a water-dispersed pressure-sensitive adhesive.
The present invention has been completed based on these findings.

That is, the present invention relates to a water-dispersed pressure-sensitive composition containing a polymer obtained by copolymerizing a monomer mixture containing a (meth) acrylic acid alkyl ester as a main component and a silane-based monomer. An adhesive composition is provided.

[0006] When this composition is polymerized with a composition containing an alkyl (meth) acrylate as a main component and containing no silane-based monomer, a resin composition having a solvent-insoluble content of 5% or less can be obtained. A monomer mixture and the monomer mixture 1
A water-dispersed pressure-sensitive adhesive composition containing a polymer obtained by copolymerizing 0.005 to 1 part by weight of a silane-based monomer with respect to 00 parts by weight under the same conditions as described above. Is also good.

The present invention also provides a method for producing a water-dispersed pressure-sensitive adhesive composition, which comprises subjecting a monomer mixture containing an alkyl (meth) acrylate ester as a main component and containing a silane-based monomer to emulsion polymerization. I will provide a. Emulsion polymerization may be performed in the presence of a chain transfer agent.

The present invention further provides a pressure-sensitive adhesive sheet having a pressure-sensitive adhesive layer comprising a copolymer of a monomer mixture containing a (meth) acrylic acid alkyl ester as a main component and a silane-based monomer. .

In the present specification, "solvent-insoluble matter"
Is that a predetermined amount (approximately 500 mg) of a sample is precisely weighed (the weight of the non-volatile matter is W ₁ mg), immersed in ethyl acetate at room temperature for 3 days, and then the insoluble matter is taken out. The material was dried at 100 ° C. for 2 hours and weighed (W ₂ m
g) was measured and calculated according to the following equation: Solvent-insoluble content (% by weight) = (W ₂ / W ₁ ) × 100.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION The alkyl (meth) acrylate used as a main constituent monomer in the present invention is represented by the following general formula (1): CH ₂ ＣC (R ¹ ) COOR ² (1) ¹ is a hydrogen atom or a methyl group, and R ² has 2 to 2 carbon atoms.
And 14 alkyl groups).

Examples of R ² include an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, an isoamyl group, a hexyl group, a heptyl group, a 2-ethylhexyl group, an isooctyl group, an isononyl group and an isodecyl group. Can be illustrated. Among them, as R ^2, butyl group,
An alkyl group having 2 to 10 carbon atoms such as a 2-ethylhexyl group is preferred. The above alkyl (meth) acrylates can be used alone or in combination of two or more. For example, butyl acrylate alone or a combination of butyl acrylate and 2-ethylhexyl acrylate can be used as the alkyl acrylate. In this case, the ratio of 2-ethylhexyl acrylate and butyl acrylate is the former / the latter = 0/100 to 55/45 (for example,
5/95 to 60/40).

The alkyl (meth) acrylate in the monomer mixture containing the alkyl (meth) acrylate as a main component [for example, the above-mentioned C _2-14 (meth) acrylate]
Alkyl ester] is generally 80% by weight or more (for example, about 80 to 99.8% by weight), and preferably 85% by weight.
% By weight (for example, about 85 to 99.5% by weight), more preferably 90% by weight or more (for example, 90 to 99% by weight).
Degree).

The monomer mixture usually contains a functional group-containing monomer (thermally crosslinkable functional group-containing monomer) in order to introduce a crosslinking point for thermal crosslinking. By using the functional group-containing monomer as a comonomer component, the adhesive strength to an adherend is also improved.

As the functional group-containing monomer, for example,
Acrylic acid, methacrylic acid, itaconic acid, maleic acid,
Carboxyl group-containing monomers such as crotonic acid and maleic anhydride or acid anhydrides thereof; 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate and the like (Meth) acrylamide, N, N-
Amide group-containing monomers such as dimethyl (meth) acrylamide, N-methylol (meth) acrylamide, N-methoxymethyl (meth) acrylamide, and N-butoxymethyl (meth) acrylamide; dimethylaminoethyl (meth) acrylate; Amino group-containing monomers such as t-butylaminoethyl (meth) acrylate; glycidyl group-containing monomers such as glycidyl (meth) acrylate; (meth)
Acrylonitrile, N- (meth) acryloylmorpholine, N-vinyl-2-pyrrolidone and the like can be mentioned. Among these, a carboxyl group-containing monomer such as acrylic acid or an acid anhydride thereof is preferred. One or more of the above functional group-containing monomers can be used.

The amount of the functional group-containing monomer to be used is, for example, 0.5 to 12 parts by weight, preferably about 1 to 8 parts by weight, based on 100 parts by weight of the alkyl (meth) acrylate.

Further, the monomer mixture may contain other copolymerizable monomers, if necessary, in order to enhance properties such as cohesion. Such copolymerizable monomers include, for example, methyl (meth) acrylate: vinyl esters such as vinyl acetate; aromatic vinyl compounds such as styrene and vinyl toluene; cyclopentyl di (meth) acrylate; A) (meth) acrylates of cyclic alcohols such as acrylates; neopentyl glycol di (meth) acrylate;
Polyhydric alcohols such as hexanediol di (meth) acrylate, propylene glycol di (meth) acrylate, trimethylolpropane tri (meth) acrylate, tetramethylol methane tri (meth) acrylate, and dipentaerythritol hexa (meth) acrylate ) Acrylic esters and the like. One or more of these copolymerizable monomers can be used.

In the present invention, the silane monomer copolymerized with the alkyl (meth) acrylate is not particularly limited as long as it is a polymerizable compound having a silicon atom. A silane compound having a (meth) acryloyl group, such as a (meth) acryloyloxyalkylsilane derivative, is preferable in that it has excellent copolymerizability with an ester. Examples of the silane monomer include 3-methacryloyloxypropyltrimethoxysilane, 3-acryloyloxypropyltrimethoxysilane, 3-methacryloyloxypropyltriethoxysilane, 3-acryloyloxypropyltriethoxysilane, 3-methacryloyloxy Examples include propylmethyldimethoxysilane, 3-acryloyloxypropylmethyldimethoxysilane, 3-methacryloyloxypropylmethyldiethoxysilane, and 3-acryloyloxypropylmethyldiethoxysilane. These silane monomers can be used alone or in combination of two or more.

Other than the above, copolymerizable silane-based monomers include, for example, vinyltrimethoxysilane, vinyltriethoxysilane, 4-vinylbutyltrimethoxysilane, 4-vinylbutyltriethoxysilane, and 8-vinylbutyltriethoxysilane.
Vinyloctyltrimethoxysilane, 8-vinyloctyltriethoxysilane, 10-methacryloyloxydecyltrimethoxysilane, 10-acryloyloxydecyltrimethoxysilane, 10-methacryloyloxydecyltriethoxysilane, 10-acryloyloxydecyltriethoxysilane, etc. Can also be used.

The amount of the silane-based monomer can be appropriately selected according to the kind and use of the alkyl (meth) acrylate. If the amount exceeds 1 part by weight with respect to 100 parts by weight of the monomer mixture containing an ester as a main component (excluding the silane-based monomer), the adhesive strength may be reduced to such an extent that the adhesive cannot be obtained. If the amount is less than 10 parts, the cohesive strength tends to decrease due to insufficient polymer strength. Therefore, in the present invention, the amount of the silane-based monomer relative to 100 parts by weight of the monomer mixture (excluding the silane-based monomer) is as follows:
The content is preferably 0.005 to 1 part by weight, more preferably 0.01 to 0.5 part by weight.

In the present invention, a crosslinking agent can be used depending on the use of the pressure-sensitive adhesive. As the crosslinking agent, a commonly used crosslinking agent can be used, and examples thereof include an isocyanate-based crosslinking agent, an epoxy-based crosslinking agent, an oxazoline-based crosslinking agent, an aziridine-based crosslinking agent, and a metal chelate-based crosslinking agent. The crosslinking agent may be either oil-soluble or water-soluble.

The water-dispersed pressure-sensitive adhesive composition of the present invention comprises:
For example, a monomer mixture containing the alkyl (meth) acrylate as a main component and containing a silane-based monomer is subjected to a conventional emulsion polymerization to obtain an aqueous dispersion of a (meth) acrylate copolymer. It can be prepared by adding the above-mentioned crosslinking agent to this, if necessary.

As the polymerization method, general batch polymerization, continuous drop polymerization, divided drop polymerization, and the like can be adopted, and the polymerization temperature is, for example, about 20 to 100 ° C. Examples of the polymerization initiator used for the polymerization include, for example, 2,2'-azobisisobutyronitrile.

Tolyl, 2,2'-azobis (2-methylpropionamidine) disulfate, 2,2'-azobis (2-amidinopropane) dihydrochloride,
2'-azobis [2- (5-methyl-2-imidazolin-2-yl) propane] dihydrochloride, 2,2 '
Azo initiators such as azobis (N, N'-dimethyleneisobutylamidine); persulfates such as potassium persulfate and ammonium persulfate; benzoyl peroxide;
peroxide initiators such as t-butyl hydroperoxide and hydrogen peroxide; substituted ethane initiators such as phenyl-substituted ethane; aromatic carbonyl compounds; a combination of persulfate and sodium bisulfite; Examples include, but are not limited to, redox-based initiators such as combinations with sodium ascorbate. The amount of the polymerization initiator to be used is, for example, about 0.005 to 1 part by weight based on 100 parts by weight of the total amount of the monomers.

In the polymerization, a chain transfer agent may be used. As the chain transfer agent, a conventional chain transfer agent, for example,
Examples include mercaptans such as dodecanethiol.
The amount of the chain transfer agent to be used is, for example, about 0.001 to 0.5 parts by weight based on 100 parts by weight of the total amount of the monomers.

Examples of the emulsifier include anionic emulsifiers such as sodium lauryl sulfate, ammonium lauryl sulfate, sodium dodecylbenzenesulfonate, sodium polyoxyethylene alkyl ether sulfate, ammonium polyoxyethylene alkyl phenyl ether sulfate and sodium polyoxyethylene alkyl phenyl ether sulfate. Nonionic emulsifiers such as polyoxyethylene alkyl ether and polyoxyethylene alkyl phenyl ether; These emulsifiers may be used alone or in combination of two or more. The amount of the emulsifier used is, for example, about 0.2 to 10 parts by weight, preferably about 0.5 to 5 parts by weight, based on 100 parts by weight of the total amount of the monomers.

The water-dispersed pressure-sensitive adhesive composition may be obtained by preparing the (meth) acrylate copolymer by a method other than emulsion polymerization in addition to the above-mentioned method, and then, if necessary, adding the crosslinking agent. It may be added and dispersed in water with an emulsifier.

The water-dispersed pressure-sensitive adhesive composition may further contain, if necessary, a base (such as aqueous ammonia) for adjusting the pH, an acid, and additives usually used for pressure-sensitive adhesives. An imparting resin, a surfactant, an antioxidant, a filler, a pigment, a colorant, and the like may be added.

In the water-dispersed pressure-sensitive adhesive composition of the present invention, when the polymerization is carried out with a composition containing (meth) acrylic acid alkyl ester as a main component and not containing a silane monomer, the solvent-insoluble content is 5%. % Or less, and a silane-based monomer in an amount of 0.005 to 1 part by weight based on 100 parts by weight of the monomer mixture. In a water-dispersed pressure-sensitive adhesive composition containing a copolymer obtained by polymerization under the same conditions as when polymerized in a composition not containing, despite being an aqueous dispersion,
It is possible to achieve both excellent terminal peelability and high retention.

The above "under the same conditions" refers to other polymerization conditions except for the presence or absence of a silane-based monomer, such as reaction temperature, reaction time, type and amount of polymerization initiator, type and amount of chain transfer agent, and the like. It means that the used amount is the same.

In the case where the monomer mixture and the silane-based monomer are polymerized with a composition containing no silane-based monomer, a monomer mixture that gives a resin composition having a solvent insoluble content exceeding 5% is obtained. , The terminal peeling property is apt to decrease.

The pressure-sensitive adhesive sheet of the present invention is provided with a pressure-sensitive adhesive layer comprising a copolymer of a monomer mixture containing a silane-based monomer and containing an alkyl (meth) acrylate as a main component.

This pressure-sensitive adhesive sheet can be obtained, for example, by applying the above-mentioned water-dispersed pressure-sensitive adhesive composition on a substrate and thermally crosslinking to form a pressure-sensitive adhesive layer. Further, by forming the pressure-sensitive adhesive layer on the separator, a pressure-sensitive adhesive sheet having no base material can be obtained.

As the substrate, for example, a plastic film such as a polypropylene film, an ethylene-propylene copolymer film, a polyester film, a polyvinyl chloride; a paper such as a kraft paper; a metal foil can be used. The plastic film may be any of a non-stretched film and a stretched (uniaxially stretched or biaxially stretched) film. The surface of the base material to which the pressure-sensitive adhesive is applied may be subjected to a surface treatment using a commonly used primer or a corona discharge method. The thickness of the substrate can be appropriately selected depending on the purpose, but is generally about 10 to 500 μm.

The water-dispersed pressure-sensitive adhesive composition is applied using a conventional coater, for example, a gravure roll coater, reverse roll coater, kiss roll coater, dip roll coater, bar coater, knife coater, spray coater and the like. It can be carried out. The water-dispersed pressure-sensitive adhesive composition, the thickness of the pressure-sensitive adhesive layer after drying,
For example, it is applied so as to have a thickness of about 10 to 100 μm.

The thermal crosslinking is performed by a conventional method, for example, by heating to a temperature at which a crosslinking reaction proceeds according to the type of the silane-based monomer or the crosslinking agent. The solvent-insoluble content of the pressure-sensitive adhesive layer after crosslinking is, for example, about 15 to 70% by weight.
The molecular weight (weight average molecular weight; standard polystyrene conversion) of the solvent-soluble portion of the pressure-sensitive adhesive layer after crosslinking is, for example, 100,000 to
It is about 600,000, preferably about 200,000 to 450,000. The molecular weight of the solvent-insoluble portion and the solvent-soluble portion of the pressure-sensitive adhesive layer after crosslinking is
For example, by appropriately adjusting the ratio of the silane-based monomer or the functional group-containing monomer to the total amount of monomers, the type and amount of the chain transfer agent or the cross-linking agent, and in particular, by appropriately adjusting the amounts of the silane-based monomer and the chain transfer agent. It can be set arbitrarily. The pressure-sensitive adhesive sheet may be a pressure-sensitive adhesive tape wound in a roll shape.

Although the pressure-sensitive adhesive sheet of the present invention uses a water-dispersed acrylic pressure-sensitive adhesive, the solvent-insoluble portion of the pressure-sensitive adhesive constituting the pressure-sensitive adhesive layer of the pressure-sensitive adhesive layer, the molecular weight of the solvent-soluble portion, and It is excellent in stability over time of the terminal peeling property when attached to a body. That is, even when the pressure-sensitive adhesive sheet is stored for a long time, the solvent-insoluble matter, the molecular weight of the solvent-soluble portion, and the fluctuation of the terminal peelability are extremely small. Therefore, high reliability is obtained.

Although the reason why such an excellent effect is exhibited is not necessarily clear, the condensation reaction of the silicon atom-containing group of the silane monomer is carried out by a simple reaction comprising a (meth) acrylic acid alkyl ester as a main component. It occurs mainly in the drying step after applying the pressure-sensitive adhesive composition to the base material, etc., rather than during copolymerization with the monomer mixture (at the time of emulsion polymerization). And therefore, excellent retention is exhibited, and since no water is interposed after drying, hydrolysis does not occur, and the condensation reaction does not proceed, so that the structure and physical properties are hardly changed, and thus good aging It is assumed that stability is obtained.

In particular, when the polymerization is carried out with a composition containing no silane-based monomer, the silane-based monomer is copolymerized with a monomer mixture such that the solvent-insoluble content at the end of the polymerization is 5% or less. In this case, since the inside and the outside of the particles of the water-dispersed pressure-sensitive adhesive are uniformly crosslinked at the time of thermal crosslinking, it is presumed that both the terminal peelability and the holding performance can be achieved at a high level.

[0039]

According to the present invention, a water-dispersed acrylic pressure-sensitive adhesive is used, which is not only desirable for environmental hygiene but also in spite of being a water-dispersed type, a solvent-insoluble matter and a molecular weight of a solvent-soluble portion. And it is excellent in the stability over time of the terminal peeling property. In addition, particularly, when a silane-based monomer is copolymerized at a specific ratio with respect to a monomer mixture in which the solvent-insoluble content of the polymer is equal to or less than a specific value, extremely excellent terminal peeling. Properties and retention are exhibited.

[0040]

The present invention will be described in more detail with reference to the following Examples, but it should not be construed that the invention is limited thereto.
“Parts” and “%” are based on weight unless otherwise specified.

Example 1 A reaction vessel equipped with a cooling pipe, a nitrogen introduction pipe, a thermometer and a stirrer was used.
30 parts of ethylhexyl, 3 parts of acrylic acid, 0.05 part of 3-methacryloyloxypropyltriethoxysilane,
Dodecanethiol (chain transfer agent) 0.07 parts, 2,2 '
-Azobis [2- (5-methyl-2-imidazoline-2)
-Yl) propane)] dihydrochloride (initiator)
0.1 part of water and 1.5 parts of sodium polyoxyethylene nonylphenyl ether sulfate (emulsifier).
After adding 0 parts to carry out emulsion polymerization, 10% ammonium water was added to adjust the pH to 8, thereby obtaining an aqueous dispersion of an acrylic copolymer. This is a 40 μm thick PET
(Polyethylene terephthalate)
After drying at 20 ° C. for 3 minutes, a pressure-sensitive adhesive sheet having a pressure-sensitive adhesive layer having a thickness of 50 μm was prepared.

Example 2 90 parts of butyl acrylate, 10 parts of 2-ethylhexyl acrylate, 4 parts of acrylic acid, 0.06 part of 3-methacryloyloxypropyltriethoxysilane, 0.05 part of dodecanethiol (chain transfer agent), 0.1 part of 2,2′-azobis [2- (5-methyl-2-imidazolin-2-yl) propane)] dihydrochloride (initiator)
Emulsion polymerization was carried out by adding 100 parts of water to which 1.5 parts of sodium polyoxyethylene nonylphenyl ether sulfate (emulsifier) was added.
By adjusting to H8, an aqueous dispersion of an acrylic copolymer was obtained. This was applied to a PET film having a thickness of 40 μm, dried at 120 ° C. for 3 minutes, and a pressure-sensitive adhesive layer having a thickness of 50 μm was attached to prepare a pressure-sensitive adhesive sheet.

Comparative Example 1 70 parts of butyl acrylate, 30 parts of 2-ethylhexyl acrylate, 3 parts of acrylic acid, 0.07 part of dodecanethiol (chain transfer agent), 2,2'-azobis [2- (5-methyl) -2-imidazolin-2-yl) propane)] 0.1 part of dihydrochloride (initiator) with sodium polyoxyethylene nonylphenyl ether sulfate (emulsifier)
The emulsion was added to 100 parts of water to which 1.5 parts had been added to carry out emulsion polymerization, and then 10% ammonium water was added to adjust the pH to 8, thereby obtaining an aqueous dispersion of an acrylic copolymer. To this, 0.05 parts of an oil-soluble epoxy-type crosslinking agent dissolved in toluene (Tetrad-C: manufactured by Mitsubishi Gas Chemical Co., Ltd.) was added, and this was applied to a PET film having a thickness of 40 μm. After drying for a minute, a pressure-sensitive adhesive sheet having a pressure-sensitive adhesive layer having a thickness of 50 μm was prepared.

Comparative Example 2 90 parts of butyl acrylate, 10 parts of 2-ethylhexyl acrylate, 4 parts of acrylic acid, 0.05 part of dodecanethiol (chain transfer agent), 2,2'-azobis [2- (5-methyl) -2-imidazolin-2-yl) propane)] 0.1 part of dihydrochloride (initiator) with sodium polyoxyethylene nonylphenyl ether sulfate (emulsifier)
The emulsion was added to 100 parts of water to which 1.5 parts had been added to carry out emulsion polymerization, and then 10% ammonium water was added to adjust the pH to 8, thereby obtaining an aqueous dispersion of an acrylic copolymer. To this was added 0.06 parts of an oil-soluble epoxy-type cross-linking agent dissolved in toluene (Tetrad-C: manufactured by Mitsubishi Gas Chemical Co., Ltd.), and this was applied to a PET film having a thickness of 40 μm. After drying for a minute, a pressure-sensitive adhesive sheet having a pressure-sensitive adhesive layer having a thickness of 50 μm was prepared.

Evaluation Test 1 With respect to the pressure-sensitive adhesives and pressure-sensitive adhesive sheets obtained in Examples 1 and 2 and Comparative Examples 1 and 2, the following characteristics were examined. Table 1 shows the results.

(Solvent Insolubles) Samples were collected from the pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet immediately after the preparation (initial stage) and the pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet prepared and allowed to stand at 50 ° C. for 14 days. Was measured.

(Molecular Weight) Samples were taken from the pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet immediately after the preparation (initial stage) and the pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet prepared and allowed to stand at 50 ° C. for 14 days. This sample was immersed in ethyl acetate for a certain period of time, the insoluble matter was filtered off, the filtrate was dried, and tetrahydrofuran (THF) was added to the residue (eluate of ethyl acetate) to prepare a 0.1% THF solution.
This was filtered through a filter having a pore diameter of 0.45 μm, and the molecular weight (molecular weight of the solvent-soluble portion; Mw) was measured by GPC (gel permeation chromatography) using the filtrate. The measurement conditions are as follows. Measurement conditions: eluent THF, liquid feed rate 1.0 ml / min,
Column temperature 38 ° C, standard polystyrene equivalent

(Terminal Peeling Test) Tape samples corresponding to the respective Examples and Comparative Examples were obtained in the same manner except that the pressure-sensitive adhesive layer was provided on a separator substrate instead of being provided on the PET film. . The tape sample immediately after the production (initial stage) and the tape sample produced and left in an atmosphere of 50 ° C. for 14 days were adhered to an aluminum plate (area: 10 mm × 100 mm) having a thickness of 0.5 mm. The separator substrate was peeled off, and the exposed pressure-sensitive adhesive layer surface was bonded to the side surface of a cylindrical acrylic round bar having a diameter of 50 mm. This was placed in an atmosphere of 70 ° C. for 2 hours, and the peeling height of the edge of the aluminum plate at that time was measured.

[0049]

[Table 1]

As is clear from Table 1, Comparative Examples 1 and 2
In the examples, the solvent-insoluble content increases with time, the molecular weight of the solvent-soluble portion decreases with time, and the terminal peelability deteriorates with time, whereas in Examples 1 and 2, the solvent-insoluble content and the solvent The molecular weight of the soluble portion hardly changed, and the terminal peelability did not deteriorate.

Example 3 A reaction vessel equipped with a cooling pipe, a nitrogen introduction pipe, a thermometer and a stirrer was used.
20 parts of ethylhexyl, 3 parts of acrylic acid, 0.05 part of 3-methacryloyloxypropyltriethoxysilane,
0.1 parts of 2,2'-azobis [2- (5-methyl-2-imidazolin-2-yl) propane)] dihydrochloride (initiator), 0.1 part of dodecanethiol (chain transfer agent).
05 parts was added to 100 parts of water to which 3 parts of sodium polyoxyethylene nonylphenyl ether sulfate (emulsifier) was added, and emulsion polymerization was performed. Then, 10% ammonium water was added to adjust the pH to 8, and the acrylic copolymer was added. An aqueous dispersion was obtained. When the polymerization was carried out in the same manner with a composition in which the silane-based monomer was not mixed, the solvent-insoluble content of the polymer at the end of the polymerization was 0%. An aqueous dispersion of the acrylic copolymer obtained above was applied to a PET (polyethylene terephthalate) film having a thickness of 40 μm, dried at 120 ° C. for 3 minutes, and provided with an adhesive layer having a thickness of 50 μm. Was prepared. The solvent-insoluble content of this pressure-sensitive adhesive layer was 50%.

Example 4 80 parts of butyl acrylate, 20 parts of 2-ethylhexyl acrylate, 3 parts of acrylic acid, 0.05 part of 3-methacryloyloxypropyltrimethoxysilane, 2,2'-azobis [2- (5- Methyl-2-imidazolin-2-yl) propane)] dihydrochloride (initiator) 0.1
Parts, 0.05 parts of dodecanethiol (chain transfer agent) was added to 100 parts of water to which 3 parts of sodium polyoxyethylene nonylphenyl ether sulfate (emulsifier) was added, followed by emulsion polymerization, followed by addition of 10% ammonium water. The pH was adjusted to 8 to obtain an aqueous dispersion of an acrylic copolymer. In addition,
When the polymerization was carried out in the same manner with a composition containing no silane-based monomer, the solvent-insoluble content of the polymer at the end of the polymerization was 0%. The aqueous dispersion of the acrylic copolymer obtained above was applied to a PET film having a thickness of 40 μm, dried at 120 ° C. for 3 minutes, and a pressure-sensitive adhesive layer having a thickness of 50 μm was provided to prepare a pressure-sensitive adhesive sheet. The solvent-insoluble content of this pressure-sensitive adhesive layer was 50%.

Example 5 80 parts of butyl acrylate, 20 parts of 2-ethylhexyl acrylate, 3 parts of acrylic acid, 0.01 part of 3-methacryloyloxypropyltriethoxysilane, 2,2'-azobis [2- (5- Methyl-2-imidazolin-2-yl) propane)] dihydrochloride (initiator) 0.1
Parts, 0.05 parts of dodecanethiol (chain transfer agent) was added to 100 parts of water to which 3 parts of sodium polyoxyethylene nonylphenyl ether sulfate (emulsifier) was added, followed by emulsion polymerization, followed by addition of 10% ammonium water. The pH was adjusted to 8 to obtain an aqueous dispersion of an acrylic copolymer. In addition,
When the polymerization was carried out in the same manner with a composition containing no silane-based monomer, the solvent-insoluble content of the polymer at the end of the polymerization was 0%. The aqueous dispersion of the acrylic copolymer obtained above was applied to a PET film having a thickness of 40 μm, dried at 120 ° C. for 3 minutes, and a pressure-sensitive adhesive layer having a thickness of 50 μm was provided to prepare a pressure-sensitive adhesive sheet. The solvent-insoluble content of this pressure-sensitive adhesive layer was 20%.

EXAMPLE 6 95 parts of butyl acrylate, 5 parts of acrylic acid, 0.05 of 3-methacryloyloxypropyltriethoxysilane
Part, 2,2'-azobis [2- (5-methyl-2-imidazolin-2-yl) propane)] dihydrochloride (initiator) 0.1 part, dodecanethiol (chain transfer agent)
0.05 parts were added to water 100 to which 3 parts of sodium polyoxyethylene nonylphenyl ether sulfate (emulsifier) was added.
Then, the emulsion polymerization was carried out in 10 parts, and the pH was adjusted to 8 by adding 10% ammonium water to obtain an aqueous dispersion of an acrylic copolymer. When the polymerization was carried out in the same manner with a composition in which the silane-based monomer was not mixed, the solvent-insoluble content of the polymer at the end of the polymerization was 0%. Applying the aqueous dispersion of the acrylic copolymer obtained above to a PET film having a thickness of 40 μm,
After drying at 120 ° C. for 3 minutes, a pressure-sensitive adhesive sheet having a pressure-sensitive adhesive layer having a thickness of 50 μm was prepared. The solvent-insoluble content of this pressure-sensitive adhesive layer was 50%.

Example 7 80 parts of butyl acrylate, 20 parts of 2-ethylhexyl acrylate, 3 parts of acrylic acid, 0.04 part of 3-methacryloyloxypropyltriethoxysilane, 2,2'-azobis [2- (5- Methyl-2-imidazolin-2-yl) propane)] dihydrochloride (initiator) 0.1
Parts, 0.05 parts of dodecanethiol (chain transfer agent) was added to 100 parts of water to which 3 parts of sodium polyoxyethylene nonylphenyl ether sulfate (emulsifier) was added, followed by emulsion polymerization, followed by addition of 10% ammonium water. The pH was adjusted to 8 to obtain an aqueous dispersion of an acrylic copolymer. In addition,
The solvent insoluble content of the polymer at the end of the polymerization when the polymerization was carried out in the same manner with the composition without the silane monomer was 0%, and the weight at the end of the polymerization when the polymerization was carried out with the composition containing the silane monomer. The combined solvent-insoluble content was 40%. To the aqueous dispersion of the acrylic copolymer obtained above, 0.02 parts of an oil-soluble epoxy-type crosslinking agent (Tetrad-C: manufactured by Mitsubishi Gas Chemical Co., Ltd.) dissolved in toluene was added, and this was added. Thickness 4
The composition was applied to a 0 μm PET film, dried at 120 ° C. for 3 minutes, and provided with an adhesive layer having a thickness of 50 μm to prepare an adhesive sheet. The solvent-insoluble content of this pressure-sensitive adhesive layer was 50%.

Comparative Example 3 80 parts of butyl acrylate, 20 parts of 2-ethylhexyl acrylate, 3 parts of acrylic acid, 2,2'-azobis [2-
(5-methyl-2-imidazolin-2-yl) propane)] 0.1 part of dihydrochloride (initiator) and 0.05 part of dodecanethiol (chain transfer agent) were added to sodium polyoxyethylene nonylphenyl ether sulfate (emulsifier) 3) The emulsion polymerization was carried out by adding 100 parts of water to which 3 parts were added, and then the pH was adjusted to 8 by adding 10% ammonium water.
An aqueous dispersion of an acrylic copolymer was obtained. At this time, the solvent-insoluble content of the acrylic copolymer was 0%. A water-soluble oxazoline-type crosslinking agent (Epocross WS-) dissolved in water is added to the aqueous dispersion of the acrylic copolymer obtained above.
500: manufactured by Nippon Shokubai Chemical Industry Co., Ltd.), and applied to a PET film having a thickness of 40 μm.
After drying at 120 ° C. for 3 minutes, a pressure-sensitive adhesive sheet having a pressure-sensitive adhesive layer having a thickness of 50 μm was prepared. The solvent-insoluble content of this pressure-sensitive adhesive layer was 50%.

Evaluation Test 2 The following characteristics were examined for the pressure-sensitive adhesives (aqueous dispersions of acrylic copolymers) and pressure-sensitive adhesive sheets obtained in Examples 3 to 7 and Comparative Example 3. Table 2 shows the results.

(Terminal Peelability Test) A tape sample having an adhesive layer attached to a separator base material according to the method of each Example and Comparative Example was applied to a 0.5 mm-thick aluminum plate (area: 10 mm × 100 mm). After sticking, the separator base material was peeled off, and the exposed surface of the pressure-sensitive adhesive layer was stuck to the side surface of a cylindrical acrylic round bar having a diameter of 50 mm. This was placed in an atmosphere of (1) 23 ° C. for 24 hours or (2) in an atmosphere of 70 ° C. for 2 hours, and then the peeling height of the edge of the aluminum plate was measured.

(Retention force test) A pressure-sensitive adhesive sheet having a width of 10 mm was adhered to a phenol resin plate with a contact area of 10 mm × 20 mm, and after 20 minutes, left at 80 ° C. for 20 minutes.
Hang the phenolic resin plate and attach 60 to the free end of the adhesive tape.
A uniform load of 0 g was applied, and the falling time of the pressure-sensitive adhesive sheet at 80 ° C. was measured.

[0060]

[Table 2]

From Table 2, it can be seen that Comparative Example 3 is inferior in terminal peeling property, while Examples 3 to 7 can achieve both excellent terminal peeling property and high holding power.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Tomoya Naito 1-1-2 Shimohozumi, Ibaraki-shi, Osaka Nitto Denko Corporation (72) Michio Umeda 1-1-2 Shimohozumi, Ibaraki-shi, Osaka No.Nitto Denko F-term (reference) 4J004 AA10 AB01 AB05 CA02 CA04 CA05 CA06 CA08 CC02 EA01 GA01 GA02 4J040 DF041 DF051 EC231 GA05 GA07 GA11 GA12 GA13 GA14 GA15 GA17 GA22 GA31 HD03 JA03 JA09 JB02 JB09 KA18 LA05 LA06 LA07

Claims (5)

[Claims] 1. A water-dispersed pressure-sensitive adhesive composition containing a polymer obtained by copolymerizing a monomer mixture containing a (meth) acrylic acid alkyl ester as a main component and a silane-based monomer. . 2. A monomer capable of obtaining a resin composition containing a (meth) acrylic acid alkyl ester as a main component and having a solvent-insoluble content of 5% or less when polymerized in a composition not containing a silane-based monomer. 2. A polymer obtained by copolymerizing the mixture and 0.005 to 1 part by weight of a silane-based monomer with respect to 100 parts by weight of the monomer mixture under the same conditions as described above. Water-dispersible pressure-sensitive adhesive composition. 3. Production of a water-dispersed pressure-sensitive adhesive composition, characterized in that a monomer mixture containing an alkyl (meth) acrylate as a main component and containing a silane-based monomer is subjected to emulsion polymerization. Method. 4. The method according to claim 3, wherein the emulsion polymerization is carried out in the presence of a chain transfer agent. 5. A pressure-sensitive adhesive sheet comprising a pressure-sensitive adhesive layer comprising a copolymer of a monomer mixture containing (meth) alkyl acrylate as a main component and containing a silane-based monomer.