JPH05320606A - Self-adhesive composition and self-adhesive tape or sheet - Google Patents

Abstract

PURPOSE:To improve the heat resistance, adhesion to a substrate at a high temp., sticking to an adherend, etc., of the an self-adhesive compsn. by compounding a specific acrylic copolymer with a tackifying resin. CONSTITUTION:90-99.9wt.% alkyl (meth)acrylate of the formula: CH2= CR<1>COOR<2> (wherein R<1> is H or methyl; and R<2> is 4-12C alkyl), 0.1-10-wt.% maleic anhydride, and 0-9.9wt.% other copolymerizable monomer are copolymerized to give an acrylic polymer. 50-95 pts.wt. the acrylic polymer is compounded with 5-50 pts.wt. tackifying resin contg. 0.1-30wt.% tackifying resin having a softening point of 150 deg.C or higher.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a pressure-sensitive adhesive composition having good heat resistance, particularly excellent adhesion to a substrate such as urethane foam at high temperature, and excellent adhesion to an adherend, and an adhesive thereof. The present invention relates to an adhesive tape or sheet using the agent composition.

[0002]

2. Description of the Related Art Urethane foam adhesive tapes having an adhesive layer laminated on the surface of a urethane foam substrate have been used for applications such as building materials, home electric appliances, cushioning materials for automobiles, and gap tapes. As such a pressure-sensitive adhesive for tape, a solvent-based pressure-sensitive adhesive mainly composed of an acrylic resin has been favored because of its excellent light resistance, durability, heat resistance, cold resistance and the like. As the use of the tape expands, there is an increasing demand for a pressure-sensitive adhesive having higher heat resistance, excellent adhesion to a base material such as urethane foam at high temperature, and excellent balance of other physical properties. ..

However, in order to improve the heat resistance of an adhesive mainly composed of an acrylic resin, an acrylic copolymer containing a large amount of a polar monomer or a monomer for enhancing cohesive force is generally used. And a method of increasing the amount of the curing agent added.

[0004]

However, the acrylic pressure-sensitive adhesive obtained by this method has a problem that the adhesive strength to an adherend is reduced and the balance with other physical properties is poor. .. The present invention solves the above-mentioned conventional problems, has excellent heat resistance, and particularly has excellent adhesiveness to a substrate such as urethane foam at a high temperature, and also has excellent adhesiveness to an adherend and the like. , And an adhesive tape or sheet using the adhesive composition.

[0005]

The present invention is of general formula CH ₂
= CR ¹ COOR ² (wherein R ¹ is hydrogen or a methyl group, R ² is an alkyl group having 4 to 12 carbon atoms), and at least one of alkyl (meth) acrylate monomers
Acrylic copolymer 50 obtained by copolymerizing seeds 90 to 99.9% by weight (in the monomer composition) and maleic anhydride 0.1 to 10% by weight (in the monomer composition) as main components
To 95 parts by weight and 5 to 50 parts by weight of a tackifying resin, wherein the tackifying resin contains 0.1 to 30% by weight of a tackifying resin having a softening temperature of 150 ° C. or higher. is there.

The present invention is a pressure-sensitive adhesive tape or sheet in which a pressure-sensitive adhesive layer comprising the pressure-sensitive adhesive composition according to claim 1 is formed on at least one surface of a substrate.

The general formula CH ₂ = used in the present invention is
CR ¹ COOR ² (wherein R ¹ is hydrogen or a methyl group,
Examples of the alkyl (meth) acrylate monomer represented by R ² is an alkyl group having a carbon number of 4 to 12), for example, n-butyl acrylate, n-octyl (meth) acrylate, and 2-ethylhexyl (meth). At least one kind of acrylate, isooctyl (meth) acrylate, isononyl (meth) acrylate, decyl (meth) acrylate and the like is used.

When the number of carbon atoms of the alkyl group of the alkyl (meth) acrylate monomer is less than 4 or exceeds 12, the glass transition temperature of the resulting acrylic copolymer becomes high, and this copolymer was used. Acrylic pressure-sensitive adhesives have low adhesive strength and initial tack to the adherend.

In the present invention, the acrylic copolymer is
At least one of alkyl (meth) acrylate monomers
Species 90 to 99.9 wt% (in monomer composition), preferably 93 to 99.5 wt% (in monomer composition) and maleic anhydride 0.1 to 10 wt% (in monomer composition), preferably 0.1. It is obtained by copolymerizing 5 to 7% by weight (in the monomer composition) as a main component. In addition to this main component, carboxylic acids having an ethylenic double bond such as (meth) acrylic acid, polar group-containing monomers such as acrylic acid esters having a hydroxyl group such as 2-hydroxyethyl (meth) acrylate, and the like, Methyl (meth) acrylate,
A monomer such as ethyl (meth) acrylate, vinyl acetate or styrene which enhances the cohesive force may be contained as a copolymerization component, and the content ratio thereof is 0 to 9.9% by weight (in the monomer composition). When the content exceeds 9.9% by weight (in the monomer composition), the acrylic pressure-sensitive adhesive using the same tends to become hard, and the adhesive strength to the adherend and the initial tack tend to decrease. ..

When the content of the alkyl (meth) acrylate monomer in the acrylic copolymer is less than 90% by weight and the content of maleic anhydride is more than 10% by weight, adhesion to the adherend is achieved. If the content of the alkyl (meth) acrylate monomer exceeds 99.9% by weight and the content of maleic anhydride is less than 0.1% by weight, the strength and the initial tack are lowered, and at the high temperature, The adhesion of the to the base material becomes low.

The pressure-sensitive adhesive of the present invention should be appropriately crosslinked in the same manner as conventional acrylic pressure-sensitive adhesives in order to improve heat resistance, particularly adhesion to a substrate at high temperature. Electron beam irradiation method, thermal cross-linking method for peroxides such as benzoyl peroxide, etc., commonly used methods include isocyanate cross-linking agent, epoxy cross-linking agent, melamine cross-linking agent, aziridine cross-linking agent, metal chelate cross-linking agent. Agent,
Alternatively, a method in which a polyfunctional monomer is added to crosslink can be adopted.

When a crosslinking agent is used, a carboxylic acid having an ethylenic double bond such as (meth) acrylic acid or a hydroxyl group such as 2-hydroxyethyl (meth) acrylate is previously contained in the acrylic copolymer. In many cases, polar group-containing monomers such as acrylates are copolymerized.

In the pressure-sensitive adhesive composition of the present invention, a tackifying resin containing a tackifying resin having a softening temperature of 150 ° C. or higher (hereinafter referred to as “high softening point tackifying resin”) is mixed with an acrylate resin. Due to the heat resistance of the adhesive,
Particularly, while improving the adhesion to the base material at high temperature, the adhesion to the adherend and the initial tack are improved to control the adhesive physical properties.

Examples of the high softening point tackifying resin include, for example,
Rosin-modified phenol resin (for example, manufactured by Arakawa Chemical Co., Ltd .: trade name "Tamanor 810": softening point 185 ° C, manufactured by the same company: trade name "Tamanor 353": softening point 155 ° C), coumarone indene resin (for example, manufactured by New Japan Iron and Steel Chemical Co., Ltd .: trade name "Esrigid", softening point: 150 ° C) and the like are used.

Examples of the tackifying resin include, in addition to the above-mentioned high softening point tackifying resin, for example, disproportionated rosin ester resins (for example, manufactured by Arakawa Chemical Co., Ltd .: trade name “Super Ester A”).
115 ”: softening point 115 ° C., manufactured by the same company: trade name“ Super Ester A125 ”, manufactured by Harima Kasei: trade name“ Hariester DS90SL ”), hydrogenated rosin ester resins, terpene phenol resins (for example, manufactured by Yasuhara Chemical Co., Ltd.) : Trade name "YS Polystar S145"), petroleum resins and the like are used.

The tackifying resin should contain 0.1 to 30% by weight of the high softening point tackifying resin based on the total amount of the tackifying resin. When the content of the high softening point tackifying resin in the tackifying resin is less than 0.1% by weight, the heat resistance, particularly the adhesion to the base material such as urethane foam at high temperature, becomes low. If it exceeds 30% by weight, the adhesive strength and the initial tack will be low.

The pressure-sensitive adhesive composition of the present invention must contain 50 to 95 parts by weight of an acrylic copolymer and 5 to 50 parts by weight of a tackifying resin containing a high softening point tackifying resin as an essential component. is there.

When the content of the acrylic copolymer in the pressure-sensitive adhesive composition is less than 50 parts by weight and the content of the tackifying resin exceeds 50 parts by weight, heat resistance, especially at high temperature, When the adhesiveness to a substrate such as urethane foam becomes low, and conversely, the content of the acrylic copolymer exceeds 95 parts by weight and the content of the tackifying resin is less than 5 parts by weight, Adhesion to the adherend and initial tack will be low.

The pressure-sensitive adhesive tape may have a pressure-sensitive adhesive layer on one side, or may have a so-called double-sided tape shape having a pressure-sensitive adhesive layer on both sides of the substrate. In the case of a double-sided tape shape, it is necessary to provide a pressure-sensitive adhesive layer made of the adhesive composition of the present invention on at least one side.

Examples of the substrate include paper, non-woven fabric, plastic film made of polyester resin such as polyolefin resin, polyolefin resin, polyurethane resin, polychloroprene resin, soft vinyl chloride resin, and plastic foam made of acrylic resin. Be done.

[0021]

The pressure-sensitive adhesive composition of the present invention has the general formula CH ₂ = CR
¹ COOR ² (wherein R ¹ is hydrogen or a methyl group, R ²
Is an alkyl (meth) having 4 to 12 carbon atoms.
At least one acrylate monomer 90-99.9
% By weight (in monomer component) and maleic anhydride 0.1-0.1
50 to 95 parts by weight of an acrylic copolymer obtained by copolymerizing 10% by weight (in the monomer component) as a main component,
Containing 5 to 50 parts by weight of a tackifying resin containing a high softening point tackifying resin as an essential component, and the content of the high softening point tackifying resin in the tackifying resin is 0.1 to 30% by weight. Thus, it is excellent in heat resistance, particularly in adhesion to a base material such as urethane foam at high temperature, and also excellent in adhesive force to an adherend and initial tack.

The pressure-sensitive adhesive tape or sheet of the present invention has the pressure-sensitive adhesive layer formed of the above-mentioned pressure-sensitive adhesive composition on at least one surface of the substrate, so that it can be used in applications requiring high heat resistance. It can be used in a state in which the pressure-sensitive adhesive layer is not peeled off from the base material such as urethane foam, and the adhesive force to the adherend and the initial tack are excellent.

[0023]

EXAMPLES Examples of the present invention will be described below. Example 1 (1) Production of acrylic pressure-sensitive adhesive composition In a four-necked flask equipped with a thermometer, a stirrer, a cooling tube and a dropping funnel, 45 parts by weight of n-butyl acrylate as an alkyl (meth) acrylate monomer and 2-
51 parts by weight of ethylhexyl acrylate, 3 parts by weight of acrylic acid, and 2-hydroxyethyl methacrylate of 0.
2 parts by weight and 1 part by weight of maleic anhydride were dissolved in 81.7 parts by weight of ethyl acetate, and after substitution with nitrogen, 0.1 part by weight of benzoyl peroxide was added dropwise at 80 ° C. as a polymerization initiator. After reacting for a period of time, 0.1 part by weight of benzoyl peroxide was further added dropwise and reacted for 3 hours. To this solution, 40.4 parts by weight of toluene was added and cooled to obtain a transparent acrylic copolymer solution.

In this acrylic copolymer solution, a rosin-modified phenol resin as a tackifying resin (manufactured by Arakawa Chemical Co., Ltd .: trade name "Tamanor 810": softening point 185) was added to 75 parts by weight of the acrylic copolymer. 3 parts by weight) and 22 parts by weight of a disproportionated rosin ester resin (manufactured by Arakawa Chemical Co., Ltd .: trade name “Super Ester A115”: softening point 115 ° C.) and an isocyanate crosslinking agent as a curing agent (manufactured by Nippon Polyurethane Co .: 1 part by weight of the product name "Coronate L") was mixed to obtain an acrylic pressure-sensitive adhesive composition.

(2) Production of Urethane Foam Adhesive Tape This acrylic pressure-sensitive adhesive composition was 145 μm (when wet) with a doctor blade on a release paper subjected to a surface release treatment.
Was applied to obtain a pressure-sensitive adhesive layer and dried at 80 ° C. for 2 minutes to form a pressure-sensitive adhesive layer.

Next, an ether type urethane foam sheet having a thickness of 10 mm and a specific gravity of 0.02 was pressure-bonded with a roll on the pressure-sensitive adhesive layer formed on the release paper, and the pressure-sensitive adhesive layer was transferred to the urethane foam. An adhesive tape was produced. Put this adhesive tape in a thermostatic chamber at a temperature of 20 ° C and a humidity of 65% RH for 1
It was cured for 0 days.

(3) Measurement of Physical Properties With respect to this urethane foam pressure-sensitive adhesive tape, curved surface adhesiveness, heat-resistant holding power, and SP adhesive force were measured. The results are shown in Table 1.

The curved surface adhesiveness, heat resistant holding power and SP adhesive strength were measured as follows. Curved surface adhesiveness A urethane foam adhesive tape having a width of 25 mm and a length of 80 mm is reciprocated by a 2 kg roll to be stuck on an iron rod having a diameter of 50 mm, and left in a room at a temperature of 20 ° C. and a humidity of 65% RH for 1 hour. After being left in a gear oven at ℃ for 4 hours and cooled, the distance at which the end of the urethane foam adhesive tape was peeled off was measured.

Heat-resistant holding power On a stainless steel plate (SUS-304), a width of 50 mm,
Stick a urethane foam adhesive tape with a length of 120 mm, and reciprocate a 2 kg roll once to bond it.
After curing for 17 hours in a room at ℃ and 65% RH, leave it in a gear oven at 80 ℃ for 20 minutes, and then place a static load of 100 g on one end of the adhesive tape so that the urethane foam adhesive tape is on the bottom (angle Is 90 ° with respect to the stainless steel plate). After being left for 1 hour, the time until the urethane foam adhesive tape dropped from the stainless steel plate or the distance peeled from the stainless steel plate was measured.

SP adhesive strength 25 mm wide on a stainless steel plate (SUS-304),
A urethane foam adhesive tape with a length of 200 mm is attached, and a 2 kg roll is reciprocated once to adhere, and the temperature is set to 20.
After being left in a room at a temperature of 65 ° C. and a humidity of 65% RH for 20 minutes, the 90 ° peel strength was measured with a tensile tester. The pulling speed is 300
mm / min.

Examples 2 to 6 and Comparative Examples 1 to 4 In the same manner as in Example 1, acrylic copolymers were obtained using the alkyl (meth) acrylate monomers shown in Table 1, and also shown in Table 1. A urethane foam pressure-sensitive adhesive tape was produced using the pressure-sensitive adhesive composition obtained by mixing the formulations, and the physical properties were measured in the same manner as in Example 1. The results are also shown in Table 1.

The formulations used are as follows. Kumaron indene resin: Nippon Steel Co., Ltd. product name: "Esrigid A150", softening temperature 150 ° C. Terpene phenol resin: Yasuhara Chemical Co., Ltd. product name: “YS Polystar S145”, softening temperature 145 ° C.

[0033]

[Table 1]

As is clear from Table 1, in each of Examples 1 to 6, the curved surface adhesiveness (80 ° C.) and the heat-resistant holding power (80 ° C.) were excellent, and the SP adhesive force was excellent. In contrast to Comparative Example 1 to Comparative Example 4, the curved surface adhesiveness (80 ° C.) and the heat-resistant holding power (80 ° C.) were low, and the SP adhesive strength was also different from Comparative Example 1 in all cases. Low.

[0035]

EFFECT OF THE INVENTION Since the pressure-sensitive adhesive composition of the present invention has the above-mentioned constitution, it is excellent in heat resistance, particularly in adhesion to a substrate such as urethane foam at high temperature, and adheres to an adherend. Excellent in strength and initial tack.

Since the pressure-sensitive adhesive tape or sheet of the present invention is constructed as described above, the pressure-sensitive adhesive layer does not peel off from the base material such as urethane foam even in applications requiring higher heat resistance. Moreover, it can be used in a state in which the adhesive force to the adherend and the initial tack are excellent.

Claims (2)

[Claims] 1. A general formula CH ₂ ═CR ¹ COOR ² (wherein R ¹ is hydrogen or a methyl group, and R ² has a carbon number of 4 to 1).
90% to 99.9% by weight of at least one kind of alkyl (meth) acrylate monomer represented by 2).
50 to 95 parts by weight of an acrylic copolymer obtained by copolymerizing (in the monomer composition) with 0.1 to 10% by weight of maleic anhydride (in the monomer composition) and tackifying resin 5 50 parts by weight of a tackifying resin having a softening temperature of 150 ° C. or higher in the tackifying resin is 0.1 to 30.
A pressure-sensitive adhesive composition, characterized in that the pressure-sensitive adhesive composition contains wt%. 2. A pressure-sensitive adhesive tape or sheet, wherein a pressure-sensitive adhesive layer comprising the pressure-sensitive adhesive composition according to claim 1 is formed on at least one surface of a substrate.