JP2002069410A - Thermal-release adhesive and adhesion member using it - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a thermal-release adhesives that firmly adheres to a material to be adhered at a normal temperature and also easily can be released by heat treatment, and provide an adhesion member using it. SOLUTION: The thermal-release adhesives includes an acrylic ester and a metha crylic ester as a constituting unit, and is prepared by means of compounding a thermal cross-linking agent of 1-50 weight parts that has in molecule at least two reactive functional groups starting a reaction due to heat, toward 100 weight parts of base polymer having a reactive functional group on a side or main chain, and thermal-foaming fine particles of 1-50 weight parts, and has a sufficient adhesion to the material to be adhered, and is characterized by a decrease of the adhesion to the material to be adhered due to an expansion and foaming of the thermal-foaming fine particles and a cross linking reaction generated from a heat-treatment.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat-peelable adhesive which has a sufficient adhesive strength to an adherend at room temperature and whose adhesive strength is remarkably reduced by heat treatment, and an electronic and The present invention relates to a heat-peelable pressure-sensitive adhesive member that is useful for protection or temporary fixing during the manufacturing process and transportation of electrical products and the like, and that can be easily peeled off by heating after use.

[0002]

2. Description of the Related Art For protection or temporary fixing during the manufacturing process and transportation of electronic and electric products and the like, an adhesive member which has sufficient adhesiveness when necessary and which can be quickly peeled off after use is desired. Various techniques have been proposed. For example, JP-A-5-43851 and JP-A-5-24
JP-A-7418, JP-A-7-61458 and JP-A-7-96964 propose a heat-foamable pressure-sensitive adhesive member containing heat-foamable fine particles. These are heat treatments after use, which reduce the adhesive strength of the pressure-sensitive adhesive layer by expansion and foaming of the heat-expandable fine particles, thereby facilitating peeling from the adherend. It is used for various purposes, such as temporary fixing at the time of dicing of green sheets and green sheet laminates, and protection of electronic components and the like. However, in order to significantly reduce the adhesive strength of these adhesive members after the heat treatment, and further to completely eliminate the adhesive strength, the adhesive strength at room temperature must be suppressed to some extent. There was a problem that the adherend could not be fixed with required strength. On the other hand, when a pressure-sensitive adhesive having an increased adhesive strength at room temperature is used, even if the heat treatment is performed, the adhesive strength is not sufficiently reduced only by the physical action of expansion and expansion of the contained thermally expandable fine particles. However, there is a problem that the adherend is not easily separated.

In order to effectively reduce the adhesive force after heating by the fine particles, it has been proposed to provide a pressure-sensitive adhesive layer with a thickness distribution, or to provide an adhesive force with a strong or weak distribution. To achieve high adhesive strength and after heat treatment,
The pressure-sensitive adhesive layer is deformed into an undulating or wavy shape, and the peeling force is reduced by greatly reducing the bonding area.
However, even in this method, the decrease in the adhesive strength when the heat treatment is performed is not sufficient, and it is difficult to easily peel the adherend.

[0004]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a heat-peelable pressure-sensitive adhesive which can firmly adhere to an adherend at room temperature and can be easily peeled off by heat treatment, and a pressure-sensitive adhesive member using the same. To provide.

[0005]

The present inventor has studied and found that:
The present inventors have found that the above problem can be solved by introducing a crosslinkable group into a base polymer and using a material that causes a decrease in tackiness due to the formation of a crosslinked structure by heating, and completed the present invention. That is, the heat-peelable pressure-sensitive adhesive of the present invention contains an acrylic acid ester and a methacrylic acid ester as constituent units, and has a base polymer 10 having a reactive functional group in a side chain or a main chain.
1 to 50 parts by weight of a thermal cross-linking agent having at least two reactive functional groups that initiate a reaction by heat in the molecule and 1 to 50 parts by weight of thermally expandable fine particles, based on 0 parts by weight. It is characterized by.

Further, the pressure-sensitive adhesive member of the present invention according to claim 2 is characterized in that an acrylic ester,
Thermal crosslinking having at least two reactive functional groups which start reaction by heat in a molecule with respect to 100 parts by weight of a base polymer having a methacrylic acid ester as a constitutional unit and having a reactive functional group in a side chain or a main chain. An adhesive member having a heat-peelable pressure-sensitive adhesive layer obtained by mixing 1 to 50 parts by weight of an agent and 1 to 50 parts by weight of heat-expandable fine particles, and has a sufficient adhesive strength to an adherend at room temperature, In addition, the adhesive force to the adherend is reduced by expansion / foaming of the thermally expandable fine particles and a crosslinking reaction between the base polymer and the thermal crosslinking agent, which are caused by the heat treatment. This adhesive member has a 180 ° peel adhesion (peel speed 300 mm / min.) To a stainless steel plate at room temperature of 800 g / 2.
In a preferred embodiment, the heat treatment at a temperature of 120 ° C. or more satisfies the physical property that the peel adhesion becomes 80 g / 25 mm or less. Further, the heat expansion type fine particles used here are preferably microencapsulated heat expansion type fine particles.

The action mechanism of the present invention is as follows. The heat-expandable fine particles are contained in the pressure-sensitive adhesive layer, foaming and / or expansion are caused by heat treatment, and irregularities are formed on the surface of the pressure-sensitive adhesive to form an uneven surface. In addition to the decrease in the contact area and the decrease in the adhesive strength, a reactive functional group capable of forming a crosslinked structure is introduced into the base polymer, and a crosslinking agent having at least two thermally reactive functional groups is contained. By forming a three-dimensional cross-linked structure by the reaction between the base polymer and the cross-linking agent by heating and achieving a decrease in the adhesive strength due to the curing of the pressure-sensitive adhesive layer, the synergistic action of the two greatly reduces the adhesive strength. This makes it possible to obtain a pressure-sensitive adhesive having excellent heat-peelability with an adherend.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail.
As the base polymer in the heat-peelable pressure-sensitive adhesive of the present invention, an acrylic ester and / or a methacrylic ester (hereinafter, appropriately referred to as (meth) acrylic ester)
Is used as a main structural unit, and a homopolymer thereof, a copolymer of two or more thereof, a copolymer of a (meth) acrylate ester with another unsaturated monomer, and a mixture thereof are used. For example, alkyl esters having 1 to 10 carbon atoms such as acrylic acid or methacrylic acid, vinyl acetate, styrene, acrylonitrile, and vinyl ethyl ether can be preferably used.

The reactive functional group introduced into the main chain or the side chain of the (meth) acrylic acid ester-based polymer may be cross-linked with a heat cross-linking agent represented by an oligomer having a heat-reactive functional group by heat treatment. Examples of the functional group include those capable of causing a reaction, such as a carboxylic acid group, a hydroxyl group, an amide group, a glycidyl group, a hydroxylmethyl group, an epoxy group, and an isocyanate group. These can be introduced directly into the base polymer, or can be introduced by copolymerizing the structural unit having such a reactive functional group as a monomer with the (meth) acrylate-based structural unit. Specific examples of such a monomer include acrylic acid, methacrylic acid, itaconic acid, hydroxyethyl methacrylate, hydroxylpropyl methacrylate, acrylamide, glycidyl methacrylate, glycidyl acrylate, methacryloyloxy isocyanate, acryloyloxy isocyanate, glycerol monoacrylate, , 6-hexanediol monomethacrylate, 2-hydroxyethyl acrylate, 2
-Hydroxymethacrylate, N-methylacrylamide, N-methylmethacrylamide and the like are used.

These monomers are introduced into the base polymer in a proportion of 10 to 80 mol%, preferably 20 to 50 mol%. When the amount of the monomer having a reactive functional group is less than 10 mol%, even if the obtained pressure-sensitive adhesive is subjected to heat treatment, the adhesive strength does not decrease satisfactorily.
If it exceeds the above, the adhesive force cannot be controlled, which is not preferable. The pressure-sensitive adhesive of the present invention needs to be blended with a thermal crosslinking agent for forming a crosslinked structure together with the base polymer.

As the thermal crosslinking agent, a blocked polyisocyanate compound, an alkyl etherified melamine compound, an epoxy compound or the like may be used in accordance with the type of the base polymer, the treatment temperature, and the like. (10 to 40 ° C.), a stable one is preferred without causing a crosslinking reaction. The amount of the thermal crosslinking agent is based on the base polymer 1
1 to 50 parts by weight, preferably 5 to 30 parts by weight, per 100 parts by weight
Parts by weight. If the compounding amount is less than 5 parts by weight, the adhesive strength due to the heat treatment is poorly reduced. If the compounding amount exceeds 50 parts by weight, a side reaction with the adherend occurs, and the adhesive cannot be peeled off or the adhesive remains on the adherend. It will be easier.

As the heat-expandable resin particles to be added to the pressure-sensitive adhesive of the present invention, known heat-expandable resin particles can be used as long as they have a particle size of about 5 to 40 μm and expand to several tens times the initial temperature when heated at 80 to 180 ° C. Although it can be used arbitrarily, preferred examples of the thermally expandable resin particles include those in which an organic solvent or the like is encapsulated in microcapsules, and those having good dispersibility in the base polymer of the adhesive are selected and used. Is preferred. As the thermally expandable resin particles, commercially available particles may be used. For example, microspheres (trade name: F manufactured by Matsumoto Yushi Seiyaku Co., Ltd.)
-20D, F-30D, and F-40D). The compounding amount of the heat-expandable resin particles is preferably in the range of 10 to 50 parts by weight per 100 parts by weight of the base polymer. May be appropriately adjusted within the above-mentioned mixing range. When the amount is less than 10 parts by weight based on 100 parts by weight of the base polymer, the adhesive strength by heat treatment is poorly reduced. It decreases significantly.

In the pressure-sensitive adhesive of the present invention, in addition to the above essential components, a tackifier, an effect agent and the like can be used in combination for the purpose of adjusting the adhesive force, as long as the effects of the present invention are not impaired. It is preferable to add a tackifier as an additive to the pressure-sensitive adhesive. The tackifier has good compatibility with the base polymer and has a molecular weight of 200 to 8000.
Is used. Specific examples thereof include rosin or derivatives thereof, petroleum resins and hydrogenated products thereof, polyterpenes, cyclopentadiene petroleum resins, and cumarone indene resins. An appropriate amount of the tackifier is 5 to 50 parts by weight per 100 parts by weight of the base polymer. If the compounding amount is less than 5 parts by weight, the tack is poor, and if it exceeds 50 parts by weight, the adhesive strength is poor and adhesive residue is liable to be formed on the adherend.

The adhesive strength can be set to any value by adding a curing agent to the adhesive in an amount of 10 parts by weight or less per 100 parts by weight of the base polymer. As such a curing agent, an isocyanate compound, an epoxy compound, an alkyl etherified melamine compound, a diol compound, an amine and the like are used. In addition, if necessary, appropriate additives such as a filler, an antioxidant, and a coloring agent may be used in combination.

The pressure-sensitive adhesive member of the present invention uses the above-mentioned heat-peelable pressure-sensitive adhesive. That is, on one or both sides of the support, a pressure-sensitive adhesive member having a pressure-sensitive adhesive layer composed of the heat-peelable pressure-sensitive adhesive, having physical properties such as a sufficient adhesive force to the adherend at room temperature, In addition, due to the expansion and foaming of the thermally expandable fine particles and the crosslinking reaction between the base polymer and the thermal crosslinking agent caused by the heat treatment, the adhesive strength to the adherend decreases. The thickness of the heat-peelable pressure-sensitive adhesive layer provided on the support is not particularly limited and may be appropriately selected depending on the purpose, but is generally in a range of 10 µm to 150 µm. The pressure-sensitive adhesive layer is provided on one side or both sides of the support as desired.For example, a normal pressure-sensitive adhesive layer having a heat-peelable pressure-sensitive adhesive layer on one side of the support and having no heat-peelable property on the other side May be provided.

As the support, a known film or sheet used as a support base for the adhesive may be appropriately selected. For example, a plastic film such as polyester or polyolefin, or a paper support such as the plastic described above may be used. A laminated film obtained by laminating is preferably used. The thickness of the support is 25 μm to 250 μm.
m is appropriate. Further, in order to improve the adhesion to the pressure-sensitive adhesive layer, the film surface of the support is preferably subjected to an adhesion improving treatment such as a corona treatment or a urethane or acrylic anchor treatment as necessary. The pressure-sensitive adhesive member of the present invention can be obtained by applying the heat-peelable adhesive on a desired surface of a support and drying to form a pressure-sensitive adhesive layer.

The adhesive strength of the pressure-sensitive adhesive member of the present invention can be appropriately adjusted according to the purpose. The 180 ° peel adhesive strength (peel speed 300 mm / min.) To a stainless steel plate at normal temperature (10 to 40 ° C.) is 800 g. / 25 mm or more, and preferably has such a property that the peel adhesion becomes 80 g / 25 mm or less by heat treatment at 120 ° C. or more. This peeling adhesive strength is in accordance with JIS Z 0237.
Can be measured according to the method described in (1). The adhesive layer of the adhesive member is preferably protected by a separator such as a plastic film until use.

The pressure-sensitive adhesive member of the present invention has excellent adhesion to the adherend by having a high pressure-sensitive adhesive layer even when the surface of the adherend is rough or when adhesive properties for firmly bonding are required. It is a pressure-sensitive adhesive member that can be easily peeled off after use by heat treatment, and the adhesive strength and the heating temperature can be set by adjusting the composition of the pressure-sensitive adhesive layer. Examples of the adherend to be adhered and used are polishing and dicing of a semiconductor wafer or a ceramic green sheet, and more specifically, when a semiconductor chip is obtained by cutting a silicon wafer, or when a capacitor is formed by cutting a ceramic sheet. Use as a temporary fixing member when obtaining chips, pattern formation on printed circuit boards, etc., application to assembly processing of glass cells and plastic cells for liquid crystal, etc., transportation to another place, etc. It can be expected to be useful for automation and automation.

[0019]

EXAMPLES The present invention will now be described specifically with reference to examples, but the present invention is not limited thereto. Example 1 A terpene liquid at 25 ° C. was added to 100 parts by weight of a base polymer composed of ethyl acrylate / 2-ethylhexyl acrylate / acrylic acid copolymer and having a dynamic elastic modulus at 25 ° C. of 2,000,000 dyne / cm ^2. -10 parts by weight of phenolic oligomer, heat-expandable resin particles (microsphere, F-100D: manufactured by Matsumoto Yushi Seiyaku Co., Ltd.) 15
1 part by weight of an isocyanate-based crosslinking agent (Coronate L: manufactured by Nippon Polyurethane Co., Ltd.) and 3 parts by weight of triglycidyl isocyanurate were added, and 50 parts by weight of toluene was added as a solvent, and the mixture was adjusted to be uniform. Thus, an adhesive composition was obtained. As a support, a 100 μm-thick polyethylene terephthalate film having one surface anchored with a modified polyacrylic resin was prepared, the adhesive composition was applied to the anchored surface, and dried at 70 ° C. for about 1 minute. An adhesive layer having a thickness of 40 μm was formed to obtain an adhesive member.

Comparative Example 1 An adhesive member was produced in the same manner as in Example 1, except that triglycidyl isocyanurate as a crosslinking agent was not added. (Comparative Example 2) An adhesive member was produced in the same manner as in Example 1 except that the thermally expandable resin particles as the foaming agent were not added.

[Evaluation of Adhesive Member] (Measurement of Adhesive Strength) A stainless steel plate (SUS3
04), the adhesive strength was measured according to the method of JIS Z 0237. (Measurement of Adhesive Strength after Heat Treatment) A stainless plate (SUS304) was used as the adherend, and after the adherend was adhered to the adhesive, the composition was placed in an oven at a temperature of 150 ° C. for 10 minutes to perform the heat treatment. Done. Thereafter, the adhesive strength was measured in the same manner as in the method described in the measurement of the adhesive strength. Table 1 shows the above evaluation results.

[0022]

[Table 1]

As is clear from Table 1, it was found that the adhesive member of the present invention had excellent adhesiveness at room temperature, the adhesiveness almost disappeared by heating at 150 ° C., and the peelability after heat treatment was excellent.

[0024]

The heat-peelable pressure-sensitive adhesive of the present invention has the advantage that it adheres firmly to the adherend at room temperature and can be easily peeled off by heat treatment. Further, the pressure-sensitive adhesive member forming the pressure-sensitive adhesive layer composed of the heat-peelable pressure-sensitive adhesive,
It is excellent in fixability and holding properties of the adherend at room temperature, and can be easily peeled off by heat treatment after use without damaging the adherend.

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 4F100 AB02 AB07 AH02B AH03B AK25B AK25G AK42A AL01B AT00A CA02B DJ05B EH46 EJ65 GB41 JL13 JL13B JL14 JL14B YY00B 4J004 AA10 AB01 AB05 4J05 DF041B DF041B DF041B

Claims (4)

[Claims] 1. Reactivity which initiates a reaction by heat in a molecule with respect to 100 parts by weight of a base polymer containing an acrylic acid ester or a methacrylic acid ester as a constituent unit and having a reactive functional group in a side chain or a main chain. A heat-peelable pressure-sensitive adhesive comprising 1 to 50 parts by weight of a thermal crosslinking agent having at least two functional groups and 1 to 50 parts by weight of heat-expandable fine particles. 2. A method according to claim 1, wherein at least one surface of the support has an acrylate ester or a methacrylate ester as a constitutional unit, and has a heat-injection molecule based on 100 parts by weight of a base polymer having a reactive functional group in a side chain or a main chain. Thermal crosslinking agent 1 having at least two reactive functional groups for initiating the reaction
50 parts by weight and a pressure-sensitive adhesive member having a heat-peelable pressure-sensitive adhesive layer obtained by mixing 1 to 50 parts by weight of heat-expandable fine particles,
At room temperature, it has sufficient adhesive strength to the adherend, and due to expansion and foaming of the heat-expandable fine particles caused by heat treatment and crosslinking reaction between the base polymer and the thermal crosslinking agent, the adhesive strength to the adherend. The pressure-sensitive adhesive member, wherein 3. A stainless steel plate at room temperature.
0 ° peel adhesion (peel speed 300 mm / min.) Is 8
The pressure-sensitive adhesive member according to claim 2, wherein the adhesive strength is not less than 00 g / 25 mm and the peeling adhesive strength is not more than 80 g / 25 mm by a heat treatment at 120 ° C or more. 4. The pressure-sensitive adhesive member according to claim 2, wherein the heat-expandable fine particles are microencapsulated heat-expandable fine particles.