JPH07133472A - Adhesive composition - Google Patents

Abstract

PURPOSE:To provide the composition excellent in initial adhesion at room temperature, capable of being thermally repeeled, and useful for masking tapes for coating automobiles, etc., by dispersing a specific particulate material in a specified acrylic adhesive. CONSTITUTION:(B) A particulate material comprising a polymer having epoxy groups is dispersed in (A) an acrylic adhesive agent having OH groups, carboxyl groups and amino groups to provide the composition. The component B in the composition preferably has a weight-average mol.wt. of >=10000, a glass transition point of >=40 deg.C and an average particle diameter of 0.01-50mum.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pressure-sensitive adhesive composition which can be re-peeled by heating.

[0002]

2. Description of the Related Art Conventionally, there is a demand for an adhesive tape which can be used as a masking tape when painting an automobile, can be easily removed by heating after painting, and can be peeled off by heating for the purpose of simplifying the work. ing.

[0003]

As an adhesive tape for the above purpose, an adhesive tape having a base sheet and an adhesive layer containing a heat-expandable resin is provided (Japanese Patent Laid-Open No. 60-252681).
Issue). Also, JP-A-59-804
In Japanese Patent Publication No. 83, a structure for achieving adhesion by heating is described.

However, the above-mentioned adhesive tape has a low adhesive strength at room temperature and cannot be used for the purpose of fixing under a load, and has been limited to masking and labels.

The present invention has been made in view of the above problems, and an object thereof is to provide a pressure-sensitive adhesive composition which has a sufficient pressure-sensitive adhesive force at room temperature and can be re-peeled by a heat treatment. Especially.

[0006]

The particulate material used in the present invention comprises a polymer having epoxy groups. The polymer having an epoxy group can be obtained by copolymerizing a monomer having an epoxy group and a vinyl group with another vinyl monomer copolymerizable with the monomer. Examples of the monomer having an epoxy group and a vinyl group include glycidyl (meth) acrylate, allyl glycidyl ether, and cyclohexeneoxy (meth) acrylate.

Examples of the copolymerizable vinyl monomer include n-butyl (meth) acrylate, isobutyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, isooctyl (meth) acrylate and isononyl (meth) acrylate. Alkyl acrylate, N-vinylpyrrolidone, acrylonitrile and the like. You may use together 1 or more types of the said vinyl monomer.

The polymer having an epoxy group needs to be a solid granular material at room temperature, and it is preferable that the weight average molecular weight thereof is 10,000 or more and the glass transition point thereof is 40 ° C. or more.

As the size of the granular material, the average particle diameter is preferably 0.1 to 50 μm when measured by a light scattering method. The smaller the average particle size, the better the reaction efficiency, but if it is less than 0.1 μm, secondary agglomeration easily occurs,
It becomes difficult to handle. Further, if it exceeds 50 μm, it exceeds the thickness of a usual adhesive tape, and it becomes difficult to use as a product form.

The acrylic adhesive used in the present invention is
It has at least one functional group selected from the group consisting of a hydroxyl group, a carboxyl group and an amino group. The acrylic pressure-sensitive adhesive is n-butyl (meth) acrylate,
Copolymerization of alkyl (meth) acrylate monomers such as 2-ethylhexyl (meth) acrylate, isobutyl (meth) acrylate, isooctyl (meth) acrylate and isononyl (meth) acrylate with vinyl monomers having a hydroxyl group, a carboxyl group or an amino group It is united.

As the vinyl monomer having a hydroxyl group,
For example, 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, 4-hydroxybutyl acrylate and the like can be mentioned. In addition, examples of the vinyl monomer having a carboxyl group include (meth) acrylic acid, maleic acid, fumaric acid, and itaconic acid. Further, as the vinyl monomer having an amino group,
For example, amino (meth) acrylate and the like can be mentioned.

The blending amount of the vinyl monomer is preferably 0.5 to 20 parts by weight with respect to 100 parts by weight of the alkyl (meth) acrylate monomer. Moreover, you may use together 1 or more types of an alkyl (meth) acrylate monomer and a vinyl monomer.

A cross-linking agent may be added to the acrylic pressure-sensitive adhesive in order to increase cohesive force. As such a cross-linking agent, N, N′-hexamethylene-1,6-bis (1-
Aziridinecarboxamide), N, N′-diphenylmethane-4,4′-bis (1-aziridinecarboxamide), trimethylolpropane-tri-β-aziridinylpropionate, and other bifunctional or higher aziridine compounds. Preferred examples include: The amount of the crosslinking agent added is 0.001 to 100 parts by weight of the copolymer.
10 parts by weight is preferred.

To obtain the above copolymer, a usual solution polymerization method or photopolymerization method is used. In the case of solution polymerization, examples of the polymerization initiator include benzoyl peroxide and azoisobutyronitrile. In the case of the photopolymerization method, as a photopolymerization initiator, for example, 4- (2-hydroxyethoxy) phenyl (2-hydroxy-2-propyl) ketone, α-hydroxy-α, α′-dimethyl-acetophenone, etc. Examples thereof include acetophenone type, benzoyl ethyl ether, benzoin propyl ether and other benzoin ether type, and benzyl dimethyl ether ketal.

Further, a tackifying resin may be added to the acrylic pressure-sensitive adhesive in order to enhance the adhesive strength. Examples of the tackifying resin include rosin-based resins such as hydrogenated rosin ester and pentaerythritol ester of polymerized rosin, alicyclic saturated hydrocarbon resin, terpene resin, terpene phenol resin, aromatic modified terpene resin, carbon number 5 or 9 Examples include petroleum resin and coumaroindene resin. The addition amount of the tackifying resin is preferably 10 to 70 parts by weight with respect to 100 parts by weight of the copolymer.

The pressure-sensitive adhesive composition of the present invention is contained in the acrylic pressure-sensitive adhesive in a state in which particles made of a polymer having an epoxy group are dispersed. The particles are dispersed in a uniform state. It is preferable that the peelability can be efficiently expressed during the reaction. The amount of the particulate matter added is 100 parts by weight of the acrylic adhesive,
0.1 to 30 parts by weight is preferable. If it is less than 0.1 part by weight, removability due to heating cannot be obtained. Also,
This is because if the amount exceeds 30 parts by weight, it becomes difficult to obtain the initial adhesive strength.

If necessary, an organic or inorganic viscosity modifier may be added to the pressure-sensitive adhesive composition of the present invention. If the viscosity is increased, the thickness can be kept constant during coating. As a result, it becomes easy to adjust the thickness of the pressure-sensitive adhesive layer.
Preferable examples of the viscosity modifier include acrylic rubber for organic type and Aerosil for inorganic type.

A pressure-sensitive adhesive tape is obtained by applying the pressure-sensitive adhesive composition of the present invention to one surface of a base film such as a synthetic resin. When such an adhesive tape is attached to an adherend and then heated, an adhesive tape capable of removability is obtained.

[0019]

In the pressure-sensitive adhesive composition of the present invention, the acrylic pressure-sensitive adhesive does not react with the hydroxyl group, carboxyl group or amino group of the acrylic pressure-sensitive adhesive, since the granular material made of the polymer having an epoxy group does not react at room temperature. A high adhesive force can be expressed mainly by the adhesive force of the resin. Also, when heated at high temperature, the granular material composed of a polymer having an epoxy group is melted, and the epoxy group reacts with the hydroxyl group, carboxyl group or amino group in the acrylic pressure-sensitive adhesive to crosslink in the pressure-sensitive adhesive. The degree becomes higher. Further, as the degree of cross-linking increases, the tackifying resin in the pressure sensitive adhesive bleeds to the pressure sensitive adhesive surface, and the adhesive strength to the adherend decreases.

[0020]

EXAMPLES Examples of the present invention will be described below.
(Parts by weight are hereinafter abbreviated as parts) (Example 1) 40 parts of glycidyl methacrylate, 60 parts of isobutyl methacrylate, 4- (2-hydroxyethoxy) phenyl- (2-hydroxy-2-propyl) ketone (manufactured by Ciba Geigy) , Product name "Darocur 295
9 "] 2 parts, and acrylic rubber [manufactured by Toa Paint Co.,
2.5 parts of the product name "PS-250"] was uniformly mixed, sandwiched between sheets of peelable polyester film, and irradiated with 15 mW of ultraviolet rays for 20 minutes to obtain a polymer having an epoxy group. The polymer was pulverized with a ball mill to obtain granules having an average particle diameter of 5 μm.

Then, n-butyl acrylate / 2-ethylhexyl acrylate / acrylic acid = 48.5 / 4
A weight average molecular weight of 50 at a weight ratio of 8.5 / 3.0 is 50.
Hydrogenated rosin ester [manufactured by Rika Hercares Co., Ltd. under the trade name "Foral 10"]
5 "] 15 parts, pentaerythritol ester of polymerized rosin [Arakawa Chemical Co., Ltd., trade name" Pencel D160 "] 1
0 part, N, N'-hexamethylene-1,6-bis (1-
Aziridine carboxamide) [Mutual Yakuko Co., Ltd., trade name "HDU"] 0.1 part of the acrylic adhesive is added to 20 parts of the above-mentioned granules, and the mixture is uniformly stirred and dispersed by a disper and applied onto a polyester sheet. After drying, an adhesive tape having an adhesive layer of 50 μm was obtained.

The above adhesive tape was cut into a width of 25 mm and attached to an ABS plate, and the adhesive strength at room temperature was 23.degree.
The adhesive strength after leaving for 0 minutes is 180 degrees, 300 mm
The result of measurement and evaluation at a speed of 1 / min was 1400 g.
In addition, as an evaluation of the adhesive strength due to heating, the same adhesive tape was heated at 110 ° C. for 10 minutes, and the adhesive strength was measured to be 400 g.

(Example 2) Glycidyl methacrylate 2
0 part, isobutyl methacrylate 80 parts, 4- (2-hydroxyethoxy) phenyl- (2-hydroxy-2-
Propyl) ketone [Ciba Geigy Co., trade name "Darocurure 2959"] 2 parts and acrylic rubber [Toa Paint Co., trade name "PS-250"] 2.5 parts are uniformly mixed to obtain a sheet of peelable polyester. Sandwiched between films,
It was irradiated with 15 mW of ultraviolet rays for 20 minutes to obtain a polymer having an epoxy group. This polymer in a ball mill,
By pulverizing, a granular material having an average particle size of 5 μm was obtained.

Then, n-butyl acrylate / 2-ethylhexyl acrylate / acrylic acid = 48.5 / 4
A weight average molecular weight of 50 at a weight ratio of 8.5 / 3.0 is 50.
Hydrogenated rosin ester [manufactured by Rika Hercares Co., Ltd. under the trade name "Foral 10"]
5 "] 15 parts, pentaerythritol ester of polymerized rosin [Arakawa Chemical Co., Ltd., trade name" Pencel D160 "] 1
0 part, N, N'-hexamethylene-1,6-bis (1-
(Aziridinecarboxamide) [Mutual Yakuko Co., Ltd., trade name "HDU"] 0.1 part of the acrylic adhesive is added to 15 parts of the above granules, uniformly stirred and dispersed with a disper and coated on a polyester sheet. After drying, an adhesive tape having an adhesive layer of 50 μm was obtained. The adhesive strength at room temperature was measured by the same method as in Example 1 and found to be 1400 g. The adhesive strength after heat treatment was 550 g.

Comparative Example 1 An adhesive tape having an adhesive layer of 50 μm was obtained in the same manner as in Example 1 except that the above-mentioned particulate matter was not added. The adhesive strength at room temperature was measured by the same method as in Example 1 and found to be 1500 g. The adhesive strength after heat treatment is 2000g
Met.

[0026]

[Effect] The pressure-sensitive adhesive composition of the present invention has a sufficiently high initial pressure-sensitive adhesive force to an adherend at room temperature, and can be sufficiently weakened by heat treatment at about 100 ° C. Therefore, the pressure-sensitive adhesive composition of the present invention can be suitably used as a pressure-sensitive adhesive composition of a removable pressure-sensitive adhesive tape.

Claims (1)

[Claims] 1. A granular material comprising a polymer having an epoxy group, which is dispersed in an acrylic adhesive having at least one functional group selected from the group consisting of a hydroxyl group, a carboxyl group and an amino group. A characteristic adhesive composition.