JPH08157616A - Production of acrylic sheet and acrylic adhesive sheet - Google Patents

Abstract

PURPOSE: To prepare an acrylic sheet useful as an adhesive sheet for fixing a member of an automobile, etc., having excellent heat resistance, durability and reliability, by polymerizing a specific monomer mixture in an organic solvent to give a reaction solution, blending the reaction solution with a specific 'polyfunctional compound and particles, deaerating, casting and heating. CONSTITUTION: This acrylic sheet is obtained by polymerizing 60-99.9wt.% of an alkyl (meth)acrylate with 0.1-15wt.% of a functional group-containing polymerizable monomer such as an α,β-unsaturated carboxylic acid and 0-39.9wt.% of another monomer in an organic solvent such as toluene or ethyl acetate to give a reaction solution in which an acrylic copolymer (PA) is dissolved or dispersed in the organic solvent, blending the reaction solution with a polyfunctional compound (e.g. polyglycidylamine) (PB) having reactivity with the functional group in the PA and particles having 1-100μm average particle diameter in an amount of 25-50vol.% based on the amount of the PA resin, deaerating the mixture to <=10vol.% foam amount, casting and heating to remove the organic solvent and react the PB with the PA.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to an adhesive for fixing members widely used in automobiles, vehicles, ships, aircraft, construction, building materials, home appliances, office automation equipment, displays (signboards, etc.), machine parts, and general commercial products. The present invention relates to a method for producing an acrylic sheet to be used and a method for producing an acrylic adhesive sheet in which the acrylic sheet is provided with adhesiveness.

[0002]

BACKGROUND OF THE INVENTION In various fields such as automobiles, machine parts, electric appliances, and building materials, adhesives are increasingly used in parts where mechanical joining has been conventionally performed. Since an adhesive agent generally adheres adherends having different physical properties to each other, it is necessary that the adhesive agent has high adhesive strength, and the adhesive agent itself has high shearing strength and good conformability. Needed.

As a pressure-sensitive adhesive sheet used for such adhesion, Japanese Patent Publication No. 57-17030 discloses a microbubble having an average diameter of 10 to 200 μm and a specific gravity of less than 1 in an amount of 20 to 60% by volume. A thickness of 2 mm or more that is dispersed in the adhesive layer, is substantially void-free, and is 3 times or more the average diameter of the microbubbles and 2 times or more the maximum diameter. The invention of the pressure-sensitive adhesive sheet is disclosed.

The pressure sensitive adhesive layer of this pressure sensitive adhesive sheet exhibits good resistance to both peel and shear forces,
For example, it has sufficient elasticity under a short-time stress, but its elasticity becomes very low when the stress is retained for a while. When the sheet is pressed against the rough surface to be adhered, the adhesive flows into the rough surface,
Even after the pressure is removed, it adheres to the fine uneven surface and exhibits good adhesiveness.

For economic reasons, this pressure-sensitive adhesive sheet is generally produced by a method in which glass microbubbles are dispersed in a polymerizable mixture, the glass microbubbles are applied, and then they are polymerized by irradiation with ultraviolet rays. In this case, the glass microbubbles must be UV transmissive, and the UV transmissivity increases as the wall thickness decreases. That is, in this pressure-sensitive adhesive sheet, it is necessary to use glass microbubbles that are essentially UV transparent. It is disclosed that this pressure-sensitive adhesive sheet can be polymerized by heat in addition to UV irradiation, but when polymerized by heat with the disclosed composition, the polymerization rate is higher than that by UV irradiation. It will be slow and costly.

In connection with the above invention, Japanese Patent Laid-Open No. 61-27
Japanese Patent No. 2251 discloses an invention of an article filled with glass microbubbles of colored glass, and is disclosed in Japanese Patent Laid-Open No. 63-24.
Japanese Patent No. 1087 discloses an invention of a composite pressure-sensitive adhesive sheet and a method for producing the same, and Japanese Patent Application Laid-Open No. 3-237176 discloses a colored glass microbubble in which a pigment and a dye are dispersed in a photopolymerizable monomer. There is disclosed an invention of a method for producing a pressure-sensitive adhesive sheet having glass microbubbles, which is obtained by polymerizing a mixture containing γ by UV.

The above series of inventions is manufactured by dispersing thin glass microbubbles having a low specific gravity (specific gravity of 1.0 or less) in the adhesive component and polymerizing the glass microbubbles by ultraviolet polymerization or thermal polymerization. Is a pressure-sensitive adhesive sheet that
By using glass microbubbles in this sheet, it has high peeling resistance and excellent resistance to shearing force, and the UV-polymerized sheet is also excellent in economic efficiency.

However, since these pressure-sensitive adhesive sheets are basically manufactured by UV polymerization, the dispersed glass microbubbles must have UV transparency. In recent years, in addition to the function of simply adhering an object to be adhered, such a pressure-sensitive adhesive sheet is endowed with characteristics different from adhesiveness such as conductivity, flame retardancy, and colorability, and these characteristics are utilized. However, there is an increasing demand for adhesion, and in the pressure-sensitive adhesive sheet described above, the composition in which the glass microbubbles in the composition are required to have ultraviolet transparency imparts new characteristics to the pressure-sensitive adhesive sheet. Often an obstacle. Moreover, the thickness of pressure-sensitive adhesive sheets has recently become thinner except for special applications.Because the adhesive performance is emphasized rather than the weight saving of the adhesive itself, glass microbubbles with low specific gravity are used. There is no point in reducing the weight of the seat. Also,
With the diversification of needs for pressure-sensitive adhesive sheets, it is difficult to meet diversified needs with adhesive sheets that combine an adhesive and a sheet, as the range of choices for the adherend becomes narrower. Has become.

Particularly, in recent years, the demand for adhesive strength and reliability in the adhesive market for fixing members has become stricter year by year, and the double-sided tape provided with an adhesive via a core material such as nonwoven fabric has insufficient stress dispersion. It has been pointed out that there is a lack of adhesive strength. There is a strong demand for an acrylic adhesive sheet to replace such a thin double-sided tape having a thickness of 0.15 to 0.2 mm.

[0010]

An object of the present invention is to provide a core material for an adhesive sheet for fixing members, which has excellent water resistance, high durability, high reliability, is economical, and is electrically conductive, flame retardant, and colorable. It is an object of the present invention to provide a method for producing an acrylic sheet capable of imparting a desired function such as, for example, from an organic solvent type acrylic copolymer.

Further, the present invention, as an adhesive sheet for a fixing member, has excellent water resistance, high durability, high reliability, is economical, and is desired in terms of conductivity, flame retardancy, colorability, and the like. It is an object of the present invention to provide a method for producing an acrylic adhesive sheet capable of imparting a function.

[0012]

SUMMARY OF THE INVENTION A method for producing an acrylic sheet according to the present invention is (meth) acrylic acid alkyl ester 60 to 99.
9% by weight, 0.1 to 15% by weight of a polymerizable monomer having a functional group and 0 to 39.9% by weight of another monomer are polymerized in an organic solvent to give an acrylic copolymer as an organic compound. A reaction liquid dissolved or dispersed in a solvent is obtained, and then a polyfunctional compound having reactivity with a functional group in the acrylic copolymer and particles having an average particle diameter of 1 to 100 μm are added to the reaction liquid. After blending and mixing in an amount of 25 to 55% by volume with respect to the amount of resin, the amount of bubbles contained in the mixture is 1
Defoaming to 0% by volume or less, dripping the defoaming mixture, removing the organic solvent under heating, and reacting at least a part of the polyfunctional compound with the acrylic copolymer. I am trying.

Further, the method for producing an acrylic adhesive sheet of the present invention comprises: (meth) acrylic acid alkyl ester 60 to
99.9% by weight, polymerizable monomer having a functional group 0.1 to 1
5% by weight and 0 to 39.9% by weight of another monomer are polymerized in an organic solvent to obtain a reaction solution in which an acrylic copolymer is dissolved or dispersed in an organic solvent, and then, in the reaction solution,
A polyfunctional compound having reactivity with a functional group in the acrylic copolymer and particles having an average particle diameter of 1 to 100 μm are mixed in an amount of 25 to 55% by volume with respect to the resin amount of the acrylic copolymer. After mixing, the mixture is defoamed so that the amount of bubbles contained in the mixture is 10% by volume or less, and the defoaming mixture is drooled, and then the organic solvent is removed under heating and at least the polyfunctional compound is added. It is characterized in that an adhesive layer is formed on at least one surface of an acrylic sheet obtained by reacting a part with an acrylic copolymer.

In the production method of the present invention, since an acrylic sheet is produced using an organic solvent solution of an acrylic copolymer obtained by producing an acrylic copolymer in an organic solvent, water resistance is improved. It is possible to supply an acrylic sheet or an acrylic adhesive sheet which is further improved.

[0015]

DETAILED DESCRIPTION OF THE INVENTION Next, the method for producing the acrylic sheet and the method for producing the acrylic adhesive sheet of the present invention will be specifically described.

The inventor of the present invention has prepared an acrylic sheet in which solid particles having an average particle diameter of 1 to 100 μm are dispersed in a resin matrix which does not substantially contain bubbles, and a method for producing this sheet using an acrylic emulsion (Japanese Patent Application Flat 6-190593
(See Japanese Patent Application Laid-Open No. Hei 10) and an average particle size of 10 to 10 in a resin matrix containing substantially no bubbles.
An invention has already been filed for the invention of an acrylic sheet in which hollow particles of 100 μm are dispersed and a method for producing this sheet using an acrylic emulsion (see Japanese Patent Application No. 6-190594 (Japanese Patent Application Laid-Open)).

According to these specifications, the present inventor has shown that the acrylic copolymer having a functional group supplied as an emulsion has reactivity with a hollow particle or a solid particle and a functional group in the polymer. An acrylic sheet is formed by blending a polyfunctional compound, defoaming, and then spraying and drying the emulsion mixture thus obtained to react the polyfunctional compound with an acrylic copolymer having a functional group. A method is disclosed. That is, in these specifications, the inventor of the present invention supplies an acrylic copolymer having a low glass transition temperature and a viscoelastic body as an emulsion, and uses this acrylic copolymer as a matrix. Acrylic type by blending solid particles or hollow particles and polyfunctional compounds having various functions such as conductivity, flame retardancy, transparency or electromagnetic wave shielding property and stress dispersing action, and after defoaming, dripping and drying A sheet is manufactured, and an adhesive layer is formed on the surface of the acrylic sheet to manufacture an acrylic adhesive sheet. The present inventor has found that the acrylic adhesive sheet thus obtained has a pressure-sensitive adhesive sheet in which glass microbubbles are dispersed in the adhesive layer due to the stress dispersibility of hollow particles or solid particles. It was found that the adhesive performance was equivalent or higher.

However, although the water resistance of the emulsion-type polymer can be improved by using a reactive emulsifier, the reactive emulsifier and the like thus formed have a hydrophilic component, and these have a hydrophilic component after film formation. A small amount may remain in the sheet, and the small amount of the reactive emulsifier remaining may cause the water resistance of the sheet to decrease.

In the case of an emulsion type polymer, the mixing ratio of the polymerizable monomer having a functional group to the total amount of the monomers used is such that a monomer soluble in an aqueous medium such as α, β-unsaturated carboxylic acid is used. In this case, even if an attempt is made to increase the blending ratio to increase the cohesive force of the polymer, there is a quantitative limitation of the blending amount by emulsion polymerization, and there is a difference between the type of polyfunctional compound having reactivity with the functional group and the reaction conditions. Naturally, there are restrictions. Therefore, there are various restrictions as described above for producing an acrylic sheet using an emulsion polymer, and it is not easy to set the production conditions for an acrylic sheet using an emulsion polymer.

The present inventor has found that, by using an organic solvent type polymer instead of using such an emulsion type polymer, an acrylic sheet or an acrylic adhesive sheet having more excellent performance can be produced. Got

That is, the organic solvent type polymer synthesized by using an organic solvent can freely mix a polymerizable monomer having a functional group to some extent, and since an organic solvent is used, it is possible to select a polyfunctional compound. There are few restrictions on the crosslinking reaction, and coating is easy even if the viscosity is high. Therefore, even particles having a large specific gravity can be used, and the range of functionality that can be imparted to the particles can be widened. Therefore, by adopting the method of the present invention using an organic solvent, the degree of freedom in designing an acrylic sheet can be increased and various needs can be met.

Using the advantage of increased flexibility in the design of this acrylic sheet, for example, a pressure-sensitive adhesive in which a large number of carboxyl groups are introduced into the polymer to enhance the cohesive force of the polymer is used as a matrix, and a cross-linking agent, It is possible to produce an acrylic sheet having a single layer structure containing particles. This acrylic sheet having a single-layer structure, since the sheet itself has adhesiveness, unlike the acrylic adhesive sheet of the present invention described later, it is not particularly necessary to newly form an adhesive layer. The acrylic sheet having a single layer structure can be used as an adhesive sheet. Since such a single-layer acrylic sheet having adhesiveness has good adhesiveness without attaching an adhesive layer, an adhesive layer is attached to at least one surface of the acrylic sheet. Compared with the above-mentioned acrylic adhesive sheet of the present invention, there is no step of attaching an adhesive layer, so that there is an advantage that the production cost can be reduced.

Further, by using such an organic solvent type polymer, the water resistance caused by forming a film using an emulsion in which a resin has a certain affinity for water, like an emulsion type polymer, is generated. Does not cause the problem of decrease in

By using the organic solvent type polymer as described above, the water resistance of the acrylic sheet or acrylic adhesive sheet already proposed by the present inventor is further improved as compared with the case of using the emulsion type polymer. be able to.

By the way, since the organic solvent type polymer is a homogeneous system, an acrylic sheet formed by using such an organic solvent type polymer has a thick film because the polymer matrix forms a dense film structure. If the thickness exceeds 0.1 mm, a dense film is formed on the surface of the sheet during the drying process, the internal organic solvent becomes difficult to evaporate, and the organic solvent remains in the sheet to cause swelling or the surface. The gloss etc. may be impaired. Generally, organic solvents have a lower surface tension than water, and even if bubbles remain in the organic solvent solution, the bubbles tend to disappear, but the viscosity of the solution is the same as that of the organic solvent-based polymer used in the present invention. When the temperature becomes higher, the air bubbles once mixed do not easily disappear at normal temperature and pressure.

On the other hand, by mixing the particles to increase the solid content concentration in the mixture, the drying property of this mixture is improved, but by mixing the particles on the other hand, the bubbles entrained in the mixture are formed. The amount increases. Therefore, the acrylic sheet produced by applying such a mixture,
It contains a significant amount of bubbles. Therefore, in the acrylic adhesive sheet produced by transferring the pressure-sensitive adhesive layer to this acrylic sheet, the matrix polymer of the matrix polymer is used when a weak force is continuously applied to the sheet, as in the constant load peel test. Due to the low elasticity, it is observed that the sheet is stretched and the bubbles are deformed and the sheet is cleaved and cut from the bubble deformed portion.

Therefore, in the present invention, after the particles are mixed with an organic solvent solution containing a specific alkyl acrylate copolymer and a crosslinkable compound, the organic solvent solution is subjected to a defoaming treatment to contain bubbles. The amount is reduced and this is applied to produce an acrylic sheet.

That is, in the method for producing an acrylic sheet of the present invention, first, a specific amount of a (meth) acrylic acid alkyl ester, a polymerizable monomer having a functional group and another monomer are added in an organic solvent. To polymerize to obtain a reaction liquid in which the acrylic copolymer is dissolved or dispersed in an organic solvent.

The (meth) acrylic acid alkyl ester used in the present invention has an alkyl group having 1 carbon atom.
Compounds having ~ 12 alkyl groups are preferred. Examples of the (meth) acrylic acid alkyl ester having 1 to 12 carbon atoms of the alkyl group which is preferably used in the present invention include:
Methyl (meth) acrylate, ethyl (meth) acrylate, normal butyl (meth) acrylate, isopropyl (meth) acrylate, -tert-butyl (meth) acrylate, -2-ethylhexyl (meth) acrylate, ( Meta)
Examples thereof include normal octyl acrylate, isononyl (meth) acrylate, and lauryl (meth) acrylate.

These (meth) acrylic acid alkyl esters can be used alone or in combination. The polymerizable monomer having a functional group used together with the (meth) acrylic acid alkyl ester as described above includes a functional group having reactivity with a polyfunctional compound described later, and a (meth)
It is a compound having an acrylic acid alkyl ester and an ethylenic double bond which is copolymerizable. Examples of such a functional group include a carboxyl group, an amide group, a hydroxyl group, an N-alkylol group, a glycidyl group, a group having a halogen atom, and an alkoxysilyl group.

Preferable examples of the polymerizable monomer having a functional group used in the production method of the present invention include α, β-unsaturated carboxylic acid, a polymerizable monomer having an amide group, and a hydroxyl group having a hydroxyl group. Examples thereof include a polymerizable monomer, a glycidyl group-containing polymerizable monomer and a halogen atom-containing group.

The unsaturated carboxylic acid used here usually contains about 1 to 2 carboxyl groups. Specific examples of the α, β-unsaturated carboxylic acid include acrylic acid, methacrylic acid, α-ethyl acrylic acid, crotonic acid, α-methyl crotonic acid, α-ethyl crotonic acid, isocrotonic acid, tiglic acid, angelica acid. , Maleic acid, fumaric acid, itaconic acid, citraconic acid, mesaconic acid, glutaconic acid and dihydromuconic acid. Of these, acrylic acid and methacrylic acid are preferably used. These carboxyl group-containing monomers can be used alone or in combination.

Further, examples of the polymerizable monomer having an amide group as a functional group include (meth) acrylamide and tert.
-Butyl (meth) acrylamide and salts thereof can be mentioned.

Further, examples of the polymerizable monomer having a hydroxyl group include hydroxyethyl (meth) acrylate, hydroxypropyl (meth) acrylate and hydroxybutyl (meth) acrylate, ethylene glycol monoallyl ether, diethylene glycol mono. Allyl ether, glycerin monoallyl ether and the like can be mentioned, and examples of the monomer having an N-alkylol group include:
Examples thereof include N-methylol (meth) acrylamide and N-butyrol (meth) acrylamide.

Furthermore, examples of the polymerizable monomer having a glycidyl group as a functional group include glycidyl (meth) acrylate and allyl glycidyl ether.

Further, examples of the polymerizable monomer having a group having a halogen atom include vinyl chloride, vinyl bromide,
Allyl chloride, allyl bromide, 2,3-dibromopropyl (meth) acrylate, 2,3-dichloropropyl (meth) acrylate, 2-chloroethyl (meth) acrylate, 3-chloro-2-hydroxypropyl (meth) acrylate, chloro Methylstyrene, 2-bromoethyl (meth) acrylate, vinyl fluoride and the like can be mentioned. Furthermore, examples of the monomer having an alkoxysilyl group include alkoxyalkylsilane (methoxymethylsilane and the like), vinyltrimethoxysilane, vinyltriethoxysilane and 6-methacryloxypropyltrimethoxysilane.

The polymerizable monomers having these functionalities can be used alone or in combination. Among the polymerizable monomers having these functional groups, α, β-unsaturated carboxylic acid is particularly preferable.

Further, examples of the copolymerizable monomer used as necessary include monomers having a nitrile group, an N-methoxy group, an N-methoxyalkyl group, a phenyl group, an alkoxy group, and the like. You can

Among the monomers having these groups, the monomer having an N-methoxyalkyl group has a self-crosslinking property. Therefore, by copolymerizing such a monomer, a sheet polymer can be obtained. The cohesive force of can be increased.

By copolymerizing a monomer having a phenyl group, a nitrile group or a halogen group, the glass transition temperature (Tg) of the resulting copolymer can be increased, and the elasticity of the sheet polymer can be improved. Can be changed.

In addition to having the above groups, (meth)
Specific examples of the monomer copolymerizable with the acrylic acid alkyl ester and the polymerizable monomer having a functional group include (meth) acrylonitrile having a nitrile group and N-having an N-methoxyalkyl group. Methoxymethyl (meth) acrylamide, N-methoxyethyl (meth) acrylamide, N-methoxypropyl (meth) acrylamide, N-methoxybutyl (meth) acrylamide, etc. Styrene having a phenyl group, α-methylstyrene, (meth) acryl Examples thereof include phenyl acrylate and benzyl (meth) acrylate, and methoxyethyl (meth) acrylate having an alkoxy group, ethoxyethyl (meth) acrylate and the like.

The acrylic copolymer which forms the acrylic sheet of the present invention contains (meth) acrylic acid alkyl ester in an amount of 60 to 99.9% by weight, preferably 60 to 99.5.
% By weight of the polymerizable monomer having a functional group of 0.1 to 15
%, Preferably 0.5 to 15% by weight, and other monomers in an amount of 0 to 39.9% by weight, preferably 0 to 39.5% by weight, and copolymerized. It
If the amount of the (meth) acrylic acid alkyl ester is less than 60% by weight, the resulting acrylic copolymer has a high glass transition temperature (Tg) and the flexibility at low temperature is lowered. When the amount of the polymerizable monomer having a functional group is less than 0.1% by weight, the cohesive force of the polymer is extremely reduced to deteriorate the physical properties of the polymer, and the amount of the polymerizable monomer having a functional group exceeds 15% by weight. If so, the water resistance of the obtained acrylic copolymer decreases. When the amount of the other monomer exceeds 39.9% by weight, it means that the amount of the (meth) acrylic acid alkyl ester or the polymerizable monomer having a functional group is relatively decreased. The copolymer does not exhibit the desired physical properties.

In the production method of the present invention, the above monomers are dissolved in an organic solvent to prepare an alkyl acrylate copolymer by a solution polymerization method. Here, the organic solvent used in the solution polymerization may be any organic solvent capable of dissolving or dispersing (preferably dissolving) the monomer and the copolymer produced by the reaction. Examples of such organic solvents As, acetic acid esters such as ethyl acetate and butyl acetate; aromatic hydrocarbons such as toluene and xylene; ketones such as methyl ethyl ketone; aliphatic hydrocarbons such as n-hexane, n-heptane and n-octane; Examples thereof include alicyclic hydrocarbons such as cyclohexane. Considering the solubility of the monomer, these solvents may include alcohols such as methanol, ethanol and isopropyl alcohol; dioxane, dimethyl sulfoxide, dimethylformamide, N-methylpyrrolidone, ethylene glycol and the like, if necessary. A polar solvent and further water can be used in combination. These solvents are
They can be used alone or in combination depending on the blending ratio of the (meth) acrylic acid alkyl ester and the other monomer.

In the present invention, a polymerization initiator is usually used when polymerizing the above monomers. Examples of the polymerization initiator that can be used here include azo-based initiators such as azobisisobutyronitrile and azobiscyanovaleric acid, and peroxide-based initiators such as benzoyl peroxide. Initiators can be used. The type and amount of such an initiator can be appropriately determined in consideration of reaction conditions and physical properties.

The reaction temperature of the above-mentioned monomer is set to, for example, 70 to 85 ° C., and the reaction temperature is usually 3 ° C.
Allow to react for ~ 12 hours. Nonvolatile matter (solid content) in a reaction solution containing a (meth) acrylic acid alkyl ester-based copolymer having a functional group produced as described above
Is usually 20 to 80%, preferably 30 to 70%
%. That is, the amount of the monomer to be added to the organic solvent is adjusted so that the above-mentioned nonvolatile content is obtained. If the non-volatile content is less than 20%, the drying property at the time of forming a sheet tends to be poor and the viscosity of the reaction liquid itself tends to be low.
In some cases, a sufficient viscosity for coating may not be obtained even if it is added in an amount of 30% or more, and if the nonvolatile content exceeds 80%, the viscosity of the reaction solution becomes too high, and the particles are contained in a volume ratio of In 3
If the content is 0% or more, coating may not be possible.

The molecular weight of the (meth) acrylic acid alkyl ester copolymer having a functional group produced as described above is usually 150,000 or more, preferably 200,000 or more in terms of weight average molecular weight. In solution polymerization, the viscosity of the solution increases as the molecular weight of the copolymer increases, so
It is preferable to adjust the non-volatile content corresponding to the size of the molecule so that the viscosity of the solution when blending the particles is suitable for coating. If the molecular weight of the (meth) acrylic acid alkyl ester-based copolymer having a functional group is less than 150,000, in order to raise the mechanical strength of the obtained sheet to a desired value, a (meth) acrylic acid alkyl ester-based copolymer is used. Since it is necessary to increase the copolymerization amount of the monomer having a functional group to be introduced into the copolymer and the addition amount of the reactive polyfunctional compound, the amount of the reaction product for the crosslinking reaction increases. In the mixture, the cross-linking reaction progresses over a long period of time to change the molecular weight or cross-linking structure of the copolymer, and it is difficult to stabilize the physical properties of the produced sheet, and the storage conditions of the sheet or environmental changes such as heat The physical properties of the sheet may fluctuate significantly.

When the acrylic sheet is produced by the method of the present invention, a polyfunctional compound (crosslinking agent) having reactivity with the functional group introduced into the above-mentioned (meth) acrylic acid alkyl ester copolymer is used. ) Is added to form a crosslinked structure.

Examples of the group having reactivity with the functional group introduced into the (meth) acrylic acid alkyl ester-based copolymer include a carboxyl group, an isocyanate group, an epoxy group, a metal complex (metal ligand) forming group and An amino group etc. can be mentioned.

For example, when the functional group is a carboxyl group, the polyfunctional compound is preferably a polyfunctional epoxy compound, a metal chelate compound or a polyfunctional isocyanate compound, and when the functional group is an amino group, A polyfunctional isocyanate compound is preferable, as the polyfunctional compound when the functional group is a hydroxyl group, a polyfunctional isocyanate compound is preferable, and as the polyfunctional compound when the functional group is an N-alkylol group, a polyvalent carboxylic acid. , An acid anhydride or a metal chelate compound is preferable, and as the polyfunctional compound when the functional group is a glycidyl group, an acid anhydride, a metal chelate compound, an amine derivative, a hydrazine derivative or an imidazole derivative is preferable, and the functional group is a halogen atom. Only when the group has Examples of the polyfunctional compound, polyfunctional epoxy compound is preferably a metal chelate compound, polyfunctional compound in addition when the functional group is an alkoxysilyl group, metal chelate compounds, polyvalent carboxylic acids are preferred.

Especially when the functional group is a carboxyl group, a compound having a glycidyl group is suitable as the polyfunctional compound. This compound has two or more epoxy groups in the molecule and a tertiary nitrogen atom. Compounds having one or more atoms are especially preferred. Therefore, polyglycidyl amine is preferable as the polyfunctional compound having reactivity with the polymerizable monomer having the functional group.

Specific examples of the polyglycidylamine include N.N-diglycidylaniline, N.N-diglycidyltoluidine, mN.N-diglycidylaminophenylglycidyl ether, triglycidyl isocyanurate, N, N. ,
N ', N'-tetraglycidylaminodiphenylmethane and
N, N, N ', N'-tetraglycidyl-m-xylylenediamine and the like can be mentioned.

The polyfunctional compound will be described in more detail by taking polyglycidylamine as an example. Usually, it is dissolved in an organic solvent inert to polyglycidylamine and / or a plasticizer optionally incorporated, or Polyglycidylamine is used by dissolving or dispersing it in an organic solvent and / or a plasticizer together with a tackifier which is inactive to polyglycidylamine. As the tackifier used here, a hydrophobic tackifier which does not contain a group reactive with polyglycidylamine such as a carboxyl group or an amino group as a functional group is used. This tackifier preferably has a high softening point,
For example, petroleum-based hydrocarbon resins, terpene-based resins and their modified products can be used. Further, as an organic solvent for dissolving these, aromatic hydrocarbons such as toluene and xylene, and aliphatic or alicyclic hydrocarbons such as n-hexane and cyclohexane can be used. When the solubility of the cross-linking agent is low, alcohols, polar solvents such as dioxane and ethylene glycol may be mixed and used as needed. Further, examples of the plasticizer used for dissolving the crosslinking agent and, if necessary, the tackifier include dioctyl phthalate, dibutyl phthalate, dioctyl adipate and terpene plasticizers.

In the present invention, the amount of the organic solvent used when the polyfunctional compound is added can be arbitrarily selected, but generally 0.2 to 50 parts by weight of the organic solvent or the plasticizer per 1 part by weight of the polyfunctional compound. It is practical to use some parts.

In the present invention, the mixing ratio of the organic solvent solution containing the (meth) acrylic acid alkyl ester copolymer and the organic solvent or plasticizer in which the cross-linking agent is dissolved is (meth) acrylic acid alkyl ester. The functional group 1 introduced into the (meth) acrylic acid alkyl ester-based copolymer, which varies depending on the concentrations of the copolymer and the crosslinking agent.
The crosslinking agent solution is added so that 0.001 to 2 equivalents, preferably 0.005 to 1.2 equivalents of reactive groups (epoxy groups etc.) can be supplied per equivalent.

In the present invention, particles are blended with the organic solvent type polymer blended with the above-mentioned crosslinking agent. The particles may be solid or hollow, and solid particles and hollow particles may be used in combination.

The solid particles used herein are particles that do not substantially contain bubbles inside the particles. Examples of such solid particles include fine powders of conductive metals such as copper, nickel, aluminum, chromium, iron and stainless steel; metal oxides; carbides such as silicon carbide, boron carbide and nitrogen carbide; aluminum nitride, nitriding. Silicon and nitrides such as boron nitride; ceramic particles represented by oxides such as alumina and zirconia; inorganic substances such as calcium carbonate, aluminum hydroxide, glass and silica;
Natural materials such as volcanic shirasu and sand; PMMA-based particles,
PSt particles, phenol resin particles, benzoguanamine resin particles, urea resin particles, silicone resin particles,
Polymer particles such as nylon-based particles, polyester-based particles, polyurethane-based particles, polyethylene-based particles, polypropylene-based particles, polyamide-based particles and polyimide-based particles; various particles using polymerization methods or powder surface modifiers Surface modified particles and composite particles obtained by modifying the surface of the above with functional materials such as metals, pigments, dyes, flame retardants and semiconductors.

Among these solid particles, when acrylic crosslinked particles having a refractive index close to that of the acrylic polymer are dispersed in the acrylic polymer matrix, a sheet having excellent transparency is formed. It is particularly suitable for applications requiring properties.

The refractive index Np of the particles imparting transparency is related to the refractive index Nm of the polymer matrix by | Nm-N
The range of p | ≦ 0.05 is preferable. The sheet can also be made flame-retardant by incorporating solid particles of a metal salt such as aluminum hydroxide.

In addition to the solid particles as described above, hollow particles may be used in the present invention for the purpose of imparting functions such as weight reduction and heat insulation. The hollow particles can be formed of various materials such as an amorphous inorganic material, a crystalline inorganic material, and a polymer material. Examples of such hollow particles include glass balloons which are typical amorphous hollow particles, shirasu balloons synthesized from natural products, ceramic balloons having a crystalline component, polymer particle balloons, organic balloons and carbon balloons. Can be mentioned. Further, it may be a composite hollow particle in which the balloon is used as a core material and the surface of the balloon is modified with various inorganic materials, organic materials, metal materials or ceramic materials.

The particle shape of these solid particles or hollow particles may be indefinite, but it is preferably spherical in consideration of the stress dispersion in the three-dimensional direction of the sheet. Further, although expensive, monodisperse particles having a uniform particle size are particularly preferable. The particle morphology can affect the interaction of the particles with the polymer matrix, and particles with a smooth surface are usually used.

Further, surface-modified particles and composite particles in which fine particles are fixed on the surface of the core material particles are excellent in dispersibility in the polymer matrix and are particularly preferable for imparting functionality. Further, it may be an aggregate particle prepared by granulating ultrafine particles or fine particles.

When solid particles are used in the production method of the present invention, the specific gravity of the particles is 0.8 to 8.0 g / c.
It is preferably about m ³ , and when hollow particles are used, the specific gravity of the particles is preferably about 0.2 to 1.5 g / cm ³ .

The average particle size of such particles is from 1 to 10
It is necessary to be within the range of 0 μm, and further 10 to
It is preferably in the range of 80 μm. 1 to (meth) acrylic alkyl ester-based copolymer in an organic solvent solution
When the particles having an average particle diameter of 100 μm are blended, the thixotropy of the organic solvent solution increases, and this thixotropy increases as the particle diameter of the particles decreases. However, if the particle size of the particles is smaller than 1 μm, the viscosity of the mixture increases remarkably, and in order to apply, the mixture must be diluted with an organic solvent, the nonvolatile content decreases and the drying property deteriorates. Loses its flexibility and elongation, becomes highly elastic, and the balance of the physical properties of the sheet deteriorates. The average particle size is 100 μm
Beyond, settling in the mixture due to the weight of the particles,
The surface of the sheet has irregularities, and a smooth sheet cannot be obtained.
Furthermore, the shear strength for low strain is reduced. On the other hand, 1
When particles having an average particle diameter of ˜100 μm are blended to produce an adhesive sheet, the shear strength of this adhesive sheet with respect to initial low strain in shear strength-strain measurement remarkably increases. In addition, the sheets filled with 25-55% by volume of particles also showed an increase in tensile strength with respect to the initial low elongation in tensile strength-elongation measurements. This increase in strength is considered to be an increase in elastic modulus, which is 0 ° C to 50 ° C from the comparison of the viscoelasticity measurement results with the sheet not filled with particles.
This was also confirmed by the results of the increase in storage elastic modulus and loss elastic modulus in the vicinity. Also, when the mixing amount of particles is the same,
The smaller the particle size, the greater the shear strength at low strain,
On the contrary, the tensile strength tends to increase at low elongation. Therefore, when selecting the particle size of the particles, it is necessary to consider not only the price and the function but also the physical properties of the sheet to be obtained.

If the content ratio of the solid particles and / or the hollow particles is less than 25% by volume, the elasticity of the sheet is lowered, the shear strength at low strain is weak, and the stress dispersibility is deteriorated. If it exceeds 55% by volume, the elongation and tear strength of the sheet-like material will decrease.

In the present invention, in addition to the solid particles as described above, in order to impart a function to the sheet, a compound which is insoluble in a filler or water but is soluble in an organic solvent or a plasticizer is blended if necessary. You may. In addition to the solid or hollow particles as described above, an inorganic filler and an organic filler can be used in the present invention. As such a filler,
The average particle size is usually less than 1 μm, preferably 0.002
˜0.8 μm is used. Among such fillers, examples of inorganic fillers include silica, diatomaceous earth,
Magnesium oxide, antimony oxide, barium ferrite, strontium ferrite, barium oxide, pumice stone,
Oxides such as alumina fibers; hydroxides such as magnesium hydroxide and basic magnesium carbonate; sulfates or sulfites such as calcium carbonate, barium sulfate, ammonium sulfate, ammonium sulfite and calcium sulfite; talc, clay, mica, asbestos, Silicates such as glass fiber, glass beads, calcium silicate, montmorillonite and bentonite; carbons such as carbon black, graphite, carbon fiber; and molybdenum sulfide, boron fiber, zinc borate, barium metaborate, calcium borate, Examples thereof include sodium borate, silicon carbide fiber, brass fiber, single crystal potassium titanate, and lead zirconate titanate.

Examples of the organic filler include fir shell, charcoal, jute, cotton, wood powder, paper strip, cellophane strip, aromatic polyamide fiber, cellulose fiber, polyester fiber, polypropylene fiber, nylon fiber and various types. Examples thereof include polymer fine particle materials. These organic materials may be used alone or in combination, or may be used in combination with an inorganic filler.

Further, various additives may be contained in the production of this sheet. As such an additive, for example, a slip agent, a colorant, a stabilizer, an antioxidant, an anti-UV agent, an ultraviolet absorber, an antistatic agent, a flame retardant, a plasticizer and the like can be added.

In the method of the present invention, the solid particles and / or the hollow particles are blended and, if necessary, other components are blended, and then the air bubbles entrained by blending the particles and the like are removed by a vacuum degassing apparatus. Defoam using, for example.

Defoaming is carried out so that the volume of bubbles contained in the organic solvent solution is less than 10% by volume, preferably less than 5% by volume. In order to perform defoaming in this manner, the organic solvent solution is placed in, for example, a container rotary vacuum stirring defoaming device,
The atmospheric pressure in this container is reduced to about -600 to -760 mmHg (gauge pressure), and defoaming treatment is performed for 2 to 10 minutes under such reduced pressure. For the above-mentioned defoaming treatment, for example, a continuous vacuum degassing device can be used in addition to the above-mentioned container rotary stirring and defoaming device.

Further, in order to suppress the amount of bubbles entrained by the particles, the particles (powder) to be compounded are previously dispersed in an organic solvent, and the slurry-like or cake-like one is obtained by filtering and dehydrating or desolvating. You may. The average diameter of the bubbles entrained in the particles is 100 μm to several hundreds μm, but the bubble content is% by volume.
When it is 10% or more, the mechanical properties (tensile strength) of the sheet become low.

The above mixture thus prepared is
Although it is applied depending on the thickness of the sheet, it is usually applied on a release paper or a film treated with a release agent using a thin layer application device such as a die coater (T die). The coating thickness is
The dry thickness is usually about 0.05 to 1 mm. When the coating amount is more than 0.5 mm, the organic solvent is less likely to volatilize from the deep part of the sheet, and bubbles tend to be generated easily. Therefore, when forming a sheet having a thickness of 0.5 mm or more, it is advantageous to secure a predetermined thickness by laminating a thin sheet. The sheet obtained by subjecting the organic solvent-type polymer to the dripping process and the drying step has tackiness on the sheet surface, so that a laminated sheet can be easily formed by such lamination.

The viscosity of the mixture used for this coating is about 30 Poise to 1000 Poise, and it is preferable that the mixture has thixotropy. The viscosity of the mixture is 30 Pois
When it is less than e, a viscosity improver is usually added to adjust the viscosity. In addition to the purpose of increasing viscosity and imparting thixotropy, fine particle silica, organic fine particles, and crosslinked polymer gel fine particles such as microgel may be added for the purpose of increasing elasticity by dispersing in a polymer matrix.

For drying the organic solvent type polymer thus drowned, it is preferable to adopt the heat drying method because existing facilities can be used and it is economical. In such a heat drying method, infrared rays, far infrared rays, in order to improve productivity by increasing the drying speed and increasing the line speed,
Energy irradiation such as electromagnetic radiation may be used together. The above mixture undergoes a cross-linking reaction even at room temperature, but it is economically more than 40
It is preferable to dry in the temperature range of ℃ to 120 ℃. The drying time at these temperatures is usually 2 to 20 minutes. In particular, in the present invention, it is preferable to perform drying in multiple stages at a temperature lower than the boiling point of the organic solvent used, while gradually increasing the drying temperature.

By drying in this way, the acrylic sheet thus formed undergoes a crosslinking reaction in the drying step or curing at room temperature, and in many cases, intramolecular or intermolecular,
A crosslinked structure is formed by polyglycidyl amine, which is a suitable crosslinking agent for carboxyl groups.

The acrylic sheet thus obtained in a single coating and drying step has a thickness of usually 0.05 to 1 mm, preferably 0.08 to 0.8 mm. Is substantially free of bubbles. That is, the bubble content of this sheet is usually 1% by volume or less.

In the method for producing an acrylic adhesive sheet of the present invention, when the acrylic sheet has pressure-sensitive adhesive property as described above, it can be used as it is as an adhesive sheet, but more preferably as described above. A pressure-sensitive adhesive layer is formed on at least one surface, preferably both surfaces, of the acrylic sheet. As the pressure-sensitive adhesive used here, various types of adhesives such as solvent type, emulsion type and UV curing type are used in consideration of the use of the acrylic adhesive sheet and the type of adherend. It can be used according to the adhesive performance. The pressure-sensitive adhesive can be formed by, for example, a method of directly coating the surface of an acrylic sheet or a method of transferring a pressure-sensitive adhesive coated on another support to the acrylic sheet.

The thickness of the pressure sensitive adhesive layer thus formed is usually in the range of 30 to 100 μm. The sheet thus obtained is preferably used before laying the adhesive layer or after curing it after laying the adhesive layer. By curing the sheet, the strength tends to be improved.

For the acrylic sheet and the acrylic adhesive sheet produced by the method of the present invention, the (meth) acrylic acid alkyl ester copolymer reacted in an organic solvent is used as it is in an organic solvent solution, Furthermore, since particles and a cross-linking agent are added to this and defoaming treatment is applied, the resulting acrylic sheet or acrylic adhesive sheet has good water resistance and mechanical strength.

Such an acrylic adhesive sheet is used for fixing members widely used in automobiles, vehicles, ships, aircraft, construction, building materials, home appliances, office automation equipment, displays (signboards, etc.), machine parts, general commercial products, etc. Can be used for gluing.

[0080]

According to the method for producing an acrylic sheet of the present invention, a substance formed from a specific (meth) acrylic acid alkyl ester copolymer prepared by solution polymerization in an organic solvent and a crosslinking agent. Since particles having a specific particle size are dispersed in a resin matrix that does not contain bubbles, the resin matrix is rich in flexibility even at a low temperature and has a good balance between cohesive force and elongation. By using a crosslinking agent,
Since the cross-linking reaction proceeds between the functional group of the (meth) acrylic acid alkyl ester-based copolymer and the cross-linking agent, the cross-linking reaction is completed at a low temperature and the physical properties of the sheet are not changed by heat aging or aging. , Mechanical strength (tensile strength-elongation,
It is possible to produce a sheet having good shear strength-strain. Moreover, since the acrylic sheet produced by the present invention does not substantially contain bubbles and can form a dense film from a uniform solution, it is possible to prevent water from entering the sheet layer. Excellent in water resistance. Further, since the particles are contained in an amount of 25 to 55% by volume, the amount of non-volatile components in the mixture is increased, the drying property after the organic solvent solution is drowned is improved, and the mass productivity is improved. Furthermore, the acrylic sheet of the present invention is economical because it can use existing equipment.

Further, by blending the particles with particles having various functions such as conductivity, electromagnetic wave shielding property, flame retardancy, transparency, and coloring property, the acrylic sheet of the present invention can have other adhesive performance. , New functions can be added.

Further, by blending the particles, the action of relieving the stress applied to the acrylic sheet is remarkably improved, and a good pressure-sensitive adhesive and the sheet can be satisfactorily adhered.

The acrylic adhesive sheet of the present invention in which a pressure sensitive adhesive layer is formed on the surface of this acrylic sheet is
It has excellent followability to adherends, the stress distribution is significantly improved by the particle filling effect compared with conventional foamed foam materials, and it has resistance to peeling force and shearing force.
The acrylic adhesive sheet produced by the present invention has excellent adhesive strength, creep resistance (holding strength), and constant-load peeling strength, and since such excellent adhesive performance is maintained for a long period of time, Has high adhesion reliability.

Furthermore, according to the method of the present invention, an acrylic sheet can be easily produced from a copolymer solution produced by using an existing solution polymerization apparatus.

[0085]

EXAMPLES Next, the present invention will be described in more detail by showing Examples of the present invention, but the present invention should not be construed as being limited thereto.

[0086]

[Production Example 1] [Synthesis of alkyl acrylate copolymer for sheet] 320 parts by weight of toluene, 60 parts by weight of ethyl acetate, acryl in a reactor equipped with a stirrer, a cooling tube, a dropping funnel and a nitrogen gas introducing tube After charging 280 parts by weight of butyl acid, 140 parts by weight of ethyl acrylate, 12 parts by weight of acrylic acid and 0.4 parts by weight of 2-hydroxyethyl methacrylate, the temperature of the reaction system becomes 75 ° C. under a nitrogen gas stream. The temperature was raised to.

Next, azobisisobutyronitrile 4 was previously prepared.
A solution prepared by dissolving 20 parts by weight of ethyl acetate in 20 parts by weight of ethyl acetate was added dropwise to the reaction solution through the dropping funnel, and the reaction solution was kept at the same temperature for 6 hours to obtain an alkyl acrylate copolymer.

The solid content of the copolymer in this reaction solution was 49.8.
%Met. A part of this reaction solution was sampled, diluted with tetrahydrofuran, filtered, and subjected to GPC measurement (gel permeation chromatography; HL manufactured by Toyo Soda Co., Ltd.).
C-8020).

From the GPC measurement chart, the molecular weight of the obtained alkyl acrylate copolymer was converted using a calibration curve prepared from polystyrene standard molecular weight, and as a result, the weight average molecular weight of this copolymer was 270,000. Met.

[0090]

Example 1 [Preparation of transparent sheet] 200.8 parts by weight of the alkyl acrylate copolymer solution (resin content 100 parts by weight) obtained as described above was weighed in a plastic container, and toluene was added thereto. 21.4 parts by weight was added to dilute and reduce the viscosity to obtain a toluene diluted solution having a nonvolatile content of 45%.

5 parts by weight of a tetrafunctional epoxy compound N, N, N ', N'-tetraglycidyl-m-xylenediamine (trade name: TETRAD-X manufactured by Mitsubishi Gas Chemical Co., Inc.) was added to the diluted solution of toluene. Was dissolved in 45 parts by weight of toluene, and 4.0 parts by weight of the solution was added and mixed with stirring.

Then, this solution was added with an average particle size of 20 μm,
Spherical cross-linked PMMA particles with a specific gravity of 1.19 (Soken Chemical Co., Ltd.)
(Product No. MR-20G), 58 parts by weight of the solution are added while stirring the solution, and the stirring is continued for 30 minutes to form spherical crosslinked PMMA.
A solution mixture in which fine particles were uniformly dispersed was obtained.

This mixture was placed in a container rotary stirring defoaming machine (Borg II, manufactured by M & K Co., Ltd.) and the gauge pressure was -76.
It was degassed at 0 mmHg for 5 minutes. The solution thus defoamed had a nonvolatile content of 55.6%.

The defoamed solution mixture was then coated on a release paper with a 20 mil doctor blade at 10 ° C at 50 ° C.
Min, 70 ° C. for 5 minutes, and further 75 ° C. for 5 minutes. The resulting acrylic sheet had a thickness of 380 μm, had tack on the surface of the sheet, and contained no bubbles.

Table 1 shows the properties (tensile strength-elongation) and sheet thickness of the acrylic sheet obtained.

[0096]

[Example 2] [Preparation of sheet containing hollow particles] In Example 1, PM
Instead of 58 parts by weight of MA crosslinked particles, ceramic hollow particles (trade name; Microcells SL-, manufactured by Onoda Chichibu Co., Ltd.)
Acrylic sheet was manufactured in the same manner except that 40 parts by weight of 75A) was used. The average particle size of the ceramic particles is 40 μm, and the true specific gravity is 0.7.

Table 1 shows the properties (tensile strength-elongation) and sheet thickness of the obtained acrylic sheet.

[0098]

Example 3 [Preparation of Acrylic Adhesive Sheet] 150 parts by weight of SK Dyne 1386 (manufactured by Soken Chemical Industry Co., Ltd.), which is an acrylic solvent-based pressure-sensitive adhesive containing butyl acrylate as a main component, was mixed with an isocyanate curing agent. After mixing 2.75 parts by weight of a 45% solution of a certain Coronate L (manufactured by Nippon Polyurethane Co., Ltd.),
The release paper was coated with an 11 mil doctor blade.

Then, it was dried at 85 ° C. for 2 minutes to form a pressure-sensitive adhesive layer having a film thickness of 60 μm. The adhesive layer formed as described above was transferred to both sides of the acrylic sheet prepared in Example 1 and Example 2 and pressed back and forth twice with a 20 kg roller to produce an acrylic double-sided adhesive sheet. .

With respect to the obtained acrylic double-sided adhesive sheet, Peel adhesive force, holding force and 90 degree constant load peeling force were measured to evaluate the adhesive performance. The results are shown in Table 2. Table 3 shows the evaluation results of water resistance.

[0101]

[Reference Example 1] [Synthesis of emulsion for sheet (AF-2)] 450 parts by weight of deionized water and 10 parts by weight of sodium polyoxyethylene lauryl sulfate were dissolved in an emulsifier aqueous solution, and 850 parts by weight of butyl acrylate and methacrylic acid were added. Butyl acid 110
Parts by weight, 30 parts by weight of methacrylic acid, 10 parts by weight of 2-hydroxyethyl methacrylate, a reactive surfactant represented by the following formula (6-30) (manufactured by Asahi Denka Kogyo Co., Ltd., ADEKA rear soap, product number; 20 parts by weight of NE-30) was dispersed with stirring to prepare 1480 parts by weight of an aqueous monomer dispersion liquid.

[0102]

Embedded image

Separately, 480 parts by weight of deionized water was placed in a glass reactor equipped with a stirrer, a thermometer, a dropping funnel, a nitrogen gas introducing tube, and a reflux condenser, and further 20 parts by weight of ammonium persulfate and acrylic acid were added. 20 parts by weight of butyl,
An aqueous reaction mother liquor was prepared by adding 10 parts by weight of sodium dodecylbenzenesulfonate.

Then, nitrogen gas was introduced into the glass reactor to replace the air in the reactor with nitrogen gas, and then the aqueous reaction mother liquor was heated to 82 ° C. to start the reaction. Immediately after the reaction was started, 1480 parts by weight of the above monomer aqueous dispersion was dropped from this dropping funnel over 180 minutes to carry out emulsion polymerization. During this time, the temperature of the reaction solution was maintained at 82 ° C.

After 180 minutes, the temperature of the reaction solution was maintained at 82 ° C. for another 120 minutes to complete the polymerization reaction. After cooling, aqueous ammonia was added to the obtained aqueous emulsion to adjust the pH value to 8.5. The aqueous emulsion had a nonvolatile content of 51.8% by weight, and the average particle size of the emulsion polymer particles was measured and found to be 0.2 μm.
In addition, as a result of viscosity measurement using a B-type viscometer (using a No. 4 rotor), it was 30 Poise / 25 ° C at 6 rpm and 7 at 60 rpm.
It was Poise / 25 ° C.

In a plastic container equipped with a disper-type stirrer, 1930 parts by weight of the above aqueous emulsion and a tetrafunctional epoxy compound, N, N, N ', N'-tetraglycidyl-m-
Xylene diamine (Mitsubishi Gas Chemical Co., Ltd., trade name TETRA
DX) 5 parts by weight dissolved in 45 parts by weight of toluene solution 2
After weighing 0 parts by weight and stirring and mixing, it is a solid hollow ceramic hollow particle having an average particle diameter of 40 μm and a true specific gravity of 0.7 (manufactured by Onoda Chichibu Co., Ltd., trade name: Microcells, product number: SL75A). 500 parts by weight was added to the aqueous emulsion mixture while stirring, and stirring was continued for 30 minutes to obtain an aqueous emulsion mixture in which ceramic hollow particles were uniformly dispersed. This mixture was supplied to a container rotary stirring defoaming machine and defoamed for 10 minutes at a vacuum degree of -760 mmHg.

The viscosity of the thus defoamed aqueous emulsion mixture measured by a B-type viscometer (using a No. 4 rotor) was 116 Poise at 6 rpm / 25 ° C. and 22 Po at 60 rpm.
It was ise / 25 ° C.

The defoamed aqueous emulsion mixture was then coated on release paper with a 20 mil doctor blade, dried at 70 ° C. for 5 minutes and then at 90 ° C. for 20 minutes.

150 parts by weight of SK Dyne 1386 (manufactured by Soken Chemical Industry Co., Ltd.), which is an acrylic solvent-based adhesive containing butyl acrylate as a main component, and 45% of an isocyanate curing agent Coronate L (manufactured by Nippon Polyurethane Co., Ltd.). Solution 2.
After mixing 75 parts by weight, it is coated on a release paper with an 11 mil doctor blade and dried at 85 ° C. for 2 minutes to give a film thickness of 60.
A pressure sensitive adhesive of μm was obtained. This was double-sided transferred to the acrylic sheet containing the ceramic hollow particles produced in Reference Example 1 and pressed back and forth twice with a 20 kg roller to prepare a double-sided adhesive sheet.

Table 2 compares the adhesive performance of the double-sided adhesive sheet prepared in Reference Example 1 with the adhesive performance of the acrylic double-sided adhesive sheet prepared in Example 3. In the present invention, the physical properties of the sheet were measured by the methods described below.

[0111]

[Measurement of Physical Properties] The acrylic adhesive sheets produced in the above Examples and Reference Examples were attached to one side of an aluminum foil having a thickness of 75 μm, and pressed back and forth twice with a 20 kg roller.
Prepare a sample that was kept under normal conditions (23 ° C, 65% RH) for 90 ° Peel as follows.
The adhesive force, creep resistance (holding force), and 90 degree constant load peeling force (normal state and water resistance) were measured as follows.

A) 90 degree Peel adhesive strength A sample was cut into a width of 25 mm, stuck on a stainless plate, and crimped back and forth for 3 times with a 1 kg roller, and then held for 20 minutes and 24 hours under normal conditions, and then a pulling speed of 300 mm.
The 90 degree Peel peel force was measured in / min.

B) Holding power The sample was cut into a size of 20 mm x 100 mm, a 20 mm x 20 mm square area was attached to a stainless plate, and two reciprocating pressures were applied with a 1 kg roller. After leaving it in the normal state for 1 hour, 80
The sample was placed in a drier at 0 ° C. and kept for 1 hour, then a load of shearing force of 1 kg was applied to one end of the sample, and the displaced distance of the double-sided adhesive sheet was measured.

C) 90 degree constant load peeling force (normal and 80
℃) Cut the sample into 20mm × 100mm square, attach 20mm × 20mm square area to a stainless steel plate, and 1kg
Two reciprocating pressures were applied with a roller. The sample of this stainless steel plate is left in a normal temperature and constant temperature water bath of 23 ° C. for a predetermined time, and in the case of water resistance, left in a constant temperature water bath of 23 ° C. for 7 days, and then, at one end of the double-sided adhesive sheet, at right angles to the stainless steel plate. A predetermined load was applied, and the distance of the double-sided adhesive sheet from the stainless plate was measured. The water resistance test was performed by applying a predetermined load immediately after taking out from the constant temperature water tank.

D) Tensile physical properties A sample was cut into a width of 25 mm and a length of 80 mm, and 25
A marked line is drawn at the position of mm, and both ends of the sample are fixed and reinforced with vinyl tape, leaving a measurement length of 30 mm. Both ends of this sample were fixed to the chuck of the tensile tester, and the tensile speed was 300
The breaking strength (kg / cm ² ) and the breaking elongation (%) were determined by measuring in mm / min.

[0116]

[Table 1]

[0117]

[Table 2]

[0118]

[Table 3]

[Measurement Method of Moisture Content] Corona discharge treated polyethylene terephthalate (PET, thickness 50 μm) was adhered on both sides of the acrylic double-sided adhesive sheet, followed by two reciprocating pressure bonding with a 1 kg roller, and then under normal condition. It was left for one day. The sample thus prepared was cut into a size of 20 mm × 50 mm square and weighed in advance. After immersing the weighed sample in a constant temperature water bath at 23 ° C. and 60 ° C. for a predetermined time and taking it out,
Moisture adhering to PET was wiped off and immediately weighed to determine the water content and the water content from the weight difference. Incidentally, the acrylic double-sided adhesive sheet prepared in the same manner using the emulsion type polymer had a water content of 6.72% after 7 days at 60 ° C., and the acrylic prepared by the method of the present invention using an organic solvent. It was confirmed that the double-sided adhesive sheet has excellent water resistance.

Claims (8)

[Claims] 1. A (meth) acrylic acid alkyl ester 6
0-99.9% by weight, polymerizable monomer having functional group 0.1
~ 15 wt% and other monomers 0-39.9 wt%,
Polymerization in an organic solvent to obtain a reaction solution in which an acrylic copolymer is dissolved or dispersed in an organic solvent, and then the reaction solution contains a polyfunctional compound having reactivity with a functional group in the acrylic copolymer, and Particles having an average particle diameter of 1 to 100 μm are contained in an amount of 25 to 55% by volume with respect to the resin amount of the acrylic copolymer.
After mixing and mixing in an amount of 10% by volume, the mixture is defoamed so that the amount of bubbles contained in the mixture is 10% by volume or less, and the defoaming mixture is drooled, and then the organic solvent is removed under heating. At the same time, at least a part of the polyfunctional compound is reacted with the acrylic copolymer, and a method for producing an acrylic sheet. 2. The method for producing an acrylic sheet according to claim 1, wherein the acrylic copolymer has a weight average molecular weight of 150,000 or more. 3. The polymerizable monomer having the functional group,
The method for producing an acrylic sheet according to claim 1, wherein the acrylic sheet is an α, β-unsaturated carboxylic acid. 4. The method for producing an acrylic sheet according to claim 1, wherein the polyfunctional compound having reactivity with the functional group is polyglycidylamine. 5. A (meth) acrylic acid alkyl ester 6
0-99.9% by weight, polymerizable monomer having functional group 0.1
~ 15 wt% and other monomers 0-39.9 wt%,
Polymerization in an organic solvent to obtain a reaction solution in which an acrylic copolymer is dissolved or dispersed in an organic solvent, and then the reaction solution contains a polyfunctional compound having reactivity with a functional group in the acrylic copolymer, and Particles having an average particle diameter of 1 to 100 μm are contained in an amount of 25 to 55% by volume with respect to the resin amount of the acrylic copolymer.
After mixing and mixing in an amount of 10% by volume, the mixture is defoamed so that the amount of bubbles contained in the mixture is 10% by volume or less, and the defoaming mixture is drooled, and then the organic solvent is removed under heating. A method for producing an acrylic adhesive sheet, characterized in that an adhesive layer is formed on at least one surface of an acrylic sheet obtained by reacting at least a part of a polyfunctional compound with an acrylic copolymer. 6. The method for producing an acrylic adhesive sheet according to claim 5, wherein the acrylic copolymer has a weight average molecular weight of 150,000 or more. 7. The polymerizable monomer having the functional group,
The method for producing an acrylic adhesive sheet according to claim 5, which is an α, β-unsaturated carboxylic acid. 8. The method for producing an acrylic adhesive sheet according to claim 5, wherein the polyfunctional compound having reactivity with the functional group is polyglycidylamine.