JP2000239620A - Thermal release self-adhesive and self-adhesive member using same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a thermal release self-adhesive, which can strongly adhere to a body to be adhered at a normal temperature with its adhesiveness being stable over a long time and whose adhesion force lowers by thermal treatment, thereby permitting the body to be readily released, and also a self-adhesive member using same. SOLUTION: This thermal release self-adhesive comprises 100 pts.wt. of a base polymer, which consists of a polymer containing an acrylic ester monomer as constituent units or a copolymer of the monomer and other unsaturated monomer copolymerizable therewith and has a reactive functional group at the side chain thereof, 1 to 50 pts.wt. of a thermal crosslinking agent having at least two reactive functional groups capable of commencing the reaction by application of heat, and 10 to 50 pts.wt. of thermally foaming fine particles. It is preferred that the thermally foaming fine particles are microcapsulated fine particles, and that the reactive functional group of the base polymer and the thermally reactive functional groups of the crosslinking agent cause a three- dimensional reaction by heating.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention has excellent adhesive strength at room temperature and is easily peeled off by heating if desired, for protecting or temporarily fixing members during the manufacturing process and transportation of electronic and electric products and the like. The present invention relates to a heat-peelable pressure-sensitive adhesive and a pressure-sensitive adhesive member using the pressure-sensitive adhesive.

[0002]

2. Description of the Related Art In the manufacturing process of electronic and electric products,
For protection or temporary fixing of microscopic members, for example, temporary fixing at the time of dicing of silicon wafers and green sheet laminates, and for various purposes such as protection of electronic components etc. Various adhesives have been proposed which have excellent adhesiveness and, after use, reduce the adhesive strength of the adhesive layer by heat treatment to easily peel off the member from the adherend. For example, Japanese Patent Application Laid-Open No. 5-43851
No. 5-247418, No. 7-61458, No. 7
Publications such as -96964 propose a heat-expandable pressure-sensitive adhesive member containing heat-expandable fine particles. They are,
The separation is intended to be carried out by utilizing the expansion force of the fine particles foamed by heating, and it is difficult to adjust the physical properties of the pressure-sensitive adhesive used together. That is, in order to reduce or eliminate the adhesive force after the heat treatment, the adhesive force must be suppressed to some extent, and depending on the application, the adhesive force at the time when fixing is required is insufficient in performance. When a pressure-sensitive adhesive having a high force is used, there is a problem that even when the heat treatment is performed, good separation properties cannot be obtained with a separating force utilizing expansion of the fine particles.

In order to effectively reduce the adhesive strength after heating,
A pressure-sensitive adhesive layer has been proposed which has a thickness distribution and a distribution of adhesion strength. This method achieves a high adhesive strength in a thick part or a high adhesive strength part of the pressure-sensitive adhesive layer, and after the heat treatment, deforms the pressure-sensitive adhesive layer into an undulating shape or a corrugated shape to reduce the bonding area with the adherend. It is intended to decrease the peeling force by greatly reducing the peeling force. However, even in this method, the decrease in the adhesive strength when heat treatment is owed to the decrease in the adhesive area, and does not decrease the adhesive strength of the pressure-sensitive adhesive itself. It was difficult to peel off the body easily.

As a means for reducing the adhesiveness of the pressure-sensitive adhesive layer itself, JP-A-10-25456 discloses a technique in which a low molecular weight compound such as a thermosetting oligomer is added to a base polymer of the pressure-sensitive adhesive. Have been. According to this method, although a certain degree of reduction in tackiness is obtained, the addition of an effective amount of a low-molecular-weight compound exhibiting the above-mentioned effect to the tacky base polymer requires the phase of the base polymer and the oligomer. Solubility becomes a problem, and a low-molecular-weight compound is added to the polymer, so that bleeding of the low-molecular-weight compound tends to occur before the start of thermal crosslinking, which limits the formulation and also has a problem with storage stability. .

[0005]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and an object of the present invention is to allow an adherend to be firmly bonded at room temperature, and that the adhesiveness is stable for a long time. Another object of the present invention is to provide a heat-peelable pressure-sensitive adhesive capable of easily peeling off an adherend, and a pressure-sensitive adhesive member using the same, in which, if desired, the heat treatment reduces the adhesive strength.

[0006]

Means for Solving the Problems As a result of intensive studies, the present inventors have found that by combining thermally expandable fine particles with a polymer material whose adhesiveness is reduced by causing a cross-linking reaction upon heating, Finding that the purpose can be achieved,
The present invention has been completed. That is, the heat-peelable pressure-sensitive adhesive of the present invention,
A polymer containing an acrylate ester monomer as a constituent unit or a copolymer of another unsaturated monomer copolymerizable with the monomer, and a base polymer having a reactive functional group in a side chain of 100% by weight Part, 1 to 50 parts by weight of a thermal crosslinking agent having at least two reactive functional groups that initiate a reaction by heat (hereinafter, appropriately referred to as a thermally reactive functional group), and 10 to 50 parts by weight of thermally expandable fine particles. And containing. Here, the heat-expandable fine particles are microencapsulated fine particles, and a reactive functional group present in a side chain of the base polymer and a heat-reactive functional group of the crosslinking agent are heated. In a preferred embodiment, a three-dimensional cross-linking reaction is caused by the following. As a result, the heat-peelable pressure-sensitive adhesive of the present invention has a 180 ° -peeling adhesive strength (peeling speed of 30 ° C) to a stainless steel plate at 25 ° C.
0 mm / min. ) Is 800 g / 25 mm or more,
By heating to the designed peeling temperature, the adhesive strength is reduced to 8
It has excellent characteristics that it can be reduced to 0 g / 25 mm or less. Further, the pressure-sensitive adhesive member according to claim 5 of the present invention,
An adhesive layer containing the above-mentioned heat-peelable adhesive is formed on one side or both sides of the support.

[0007] The heat-peelable pressure-sensitive adhesive of the present invention, by heating,
A base polymer having a reactive functional group in the side chain and a crosslinking agent having at least two thermally reactive functional groups cause a three-dimensional crosslinking reaction, and the adhesive layer is cured and adhered as the crosslinking reaction proceeds. The power gradually decreases. Furthermore, since the base polymer itself has a crosslinkable functional group and does not require the addition of a low molecular weight component, the stability at room temperature is excellent. In addition, when the heat-expandable fine particles are contained in the pressure-sensitive adhesive layer, foaming and expansion occur due to the heat treatment, and irregularities are formed on the surface of the pressure-sensitive adhesive, thereby reducing the contact area with the adherend. By this action progressing simultaneously or sequentially,
Adhesive strength can be greatly reduced.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION As the base polymer in the heat-peelable pressure-sensitive adhesive of the present invention, an acrylic ester-based monomer is used as a main constituent unit, and a copolymer composed of two or more kinds of the monomers, Copolymers with other polymerizable unsaturated monomers and mixtures thereof are used. Examples of the acrylate-based monomer include acrylate or methacrylate having an alkyl group having about 1 to 10 carbon atoms. In addition, as monomers copolymerizable with these,
Vinyl acetate, styrene, acrylonitrile, vinyl ethyl ether and the like can be preferably used.

The base polymer of the present invention needs to have a reactive functional group capable of forming a three-dimensional crosslink with an oligomer having a thermoreactive functional group by heat treatment introduced into a side chain. Examples of such a reactive functional group include a carboxylic acid group, a hydroxyl group, an amide group, a glycidyl group, a hydroxylmethyl group, an epoxy group, an isocyanate group, and the like. Typical monomers having a reactive functional group on the side chain that can be used in the present invention include, specifically, acrylic acid, methacrylic acid, itaconic acid, hydroxyethyl methacrylate, hydroxylpropyl methacrylate, acrylamide, glycidyl methacrylate, glycidyl Acrylate, methacryloyloxyisocyanate, acryloyloxyisocyanate, glycerol monoacrylate, 1,6-hexanediol monomethacrylate, 2-hydroxyethyl acrylate, 2-hydroxymethacrylate, N-methylacrylamide, N-methylmethacrylamide and the like are used. These monomers are present in the base polymer at 10-8.
It is introduced in a proportion of 0 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 a heat treatment, the number of sites participating in the cross-linking reaction is small, so that the adhesive strength is not sufficiently reduced. If the amount exceeds mol%, it becomes difficult to control the adhesive force, which is not preferable. That is, in the present invention, the main chain of the base polymer functions as an adhesive base polymer skeleton, and a reactive group that contributes to a cross-linking reaction is introduced into a side chain, so that both are independently designed. It is possible to

The pressure-sensitive adhesive of the present invention needs to contain a thermal crosslinking agent having at least two thermally reactive functional groups in an amount of 1 to 50 parts by weight based on 100 parts by weight of the base polymer. The thermal crosslinking agent that can be used is not particularly limited as long as the number of functional groups satisfies the requirements, and can be appropriately selected and used depending on the type of the base polymer to be used, the treatment temperature, and the like. (.About.40.degree. C.) and preferably does not cause a crosslinking reaction and is stable. Specifically, for example, a blocked polyisocyanate compound, an epoxy compound, an alkyl etherified melamine compound and the like can be mentioned. The thermal crosslinking agent is blended in an amount of 1 to 50 parts by weight, preferably 5 to 30 parts by weight, per 100 parts by weight of the base polymer. If the amount is less than 1 part by weight, the adhesive strength is not easily reduced by the heat treatment. If the 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.

The heat-expandable fine particles used in the present invention are also referred to as heat-expandable resin particles, and are particles whose volume is expanded by heating. From the viewpoint of the expansion coefficient, a microcapsule containing an organic solvent or the like is included. It is preferable to use microencapsulated ones. From the viewpoint of the uniformity of the adhesive, the resin constituting the fine particles and the resin such as the microcapsule wall material have good affinity for the base polymer of the adhesive. It is preferable to select and use those having good dispersibility. The thermally expandable resin particles have a particle size of 5 to 40.
What expands several tens times the initial temperature when heated at about 80 to 180 ° C. at about μm, and such fine particles are, for example, microspheres manufactured by Matsumoto Yushi Seiyaku Co., Ltd. (trade name: F-20)
D, F-30D, F-80SD). The expansion temperature of the heat-expandable fine particles can be controlled by the wall material of the particles and the organic solvent to be enclosed. By the way, microsphere F-20D is 105-115 ° C, F-30D is 130-140 ° C,
In the case of F-80SD, the expansion temperature is 160 to 170 ° C., and the expansion (expansion) of the thermally expandable resin fine particles to be added is performed.
By selecting the temperature, the peeling design temperature can be determined.

The amount of the heat-expandable fine particles is required to be 10 to 50 parts by weight per 100 parts by weight of the base polymer, and depends on the type and thickness of the adherend, the performance of the pressure-sensitive adhesive, the use conditions, and the like. Is appropriately adjusted within the range described above. If the amount is less than 10 parts by weight, the adhesive force is not sufficiently reduced due to the heat treatment, and good releasability cannot be obtained. If the amount exceeds 50 parts by weight, uniform application is performed even when applying to a substrate to obtain an adhesive member. This makes it easy to entrap air bubbles when attaching the adherend, and the adhesion to the adherend is significantly reduced.

The heat-peelable pressure-sensitive adhesive used in the present invention includes known additives, for example, a tackifier for adjusting tackiness and adhesiveness, a curing agent, and a film as long as the effects of the present invention are not impaired. An antioxidant, a colorant, an ultraviolet absorber, a filler, and the like for improving the properties, durability, appearance, and the like can be used in combination. The pressure-sensitive adhesive of the present invention preferably contains a tackifier as an additive. The tackifier has good compatibility with the base polymer and has a molecular weight of 20.
0 to 8000 known compounds can be used. Specific examples include rosin or derivatives thereof, petroleum resins and hydrogenated products thereof, polyterpenes, cyclopentadiene-based petroleum resins, and cumarone-indene-based resins. An appropriate amount of these components 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, tackiness is poor and the effect of addition cannot be obtained.
If the amount is more than the weight part, adhesive residue is apt to occur on the adherend, which is not preferable. In addition, a curing agent capable of crosslinking and curing at room temperature is added to the adhesive in an amount of 10 parts by weight or less per 100 parts by weight of the base polymer, so that the adhesive strength can be adjusted to an arbitrary value.
As such a curing agent, a polyisocyanate compound, an epoxy compound, an alkyl etherified melamine compound, a diol compound, an amine and the like are used. As other additives, if necessary, a reaction accelerator, a filler,
An antioxidant, a coloring agent, and the like may be used in combination.

The adhesive strength of the heat-peelable pressure-sensitive adhesive thus adjusted is 1 at 25 ° C. for a stainless steel plate.
The 80 ° peel adhesive strength (peel rate 300 mm / min.) Is preferably 800 g / 25 mm or more,
More preferably, it is 0 g / 25 mm or more. If the adhesive strength at room temperature is less than 800 g / 25 mm, the adherend cannot be sufficiently held, which is not practical. Further, the adhesive strength after heating to a temperature at which peeling is to be caused, that is, a heating temperature at which the peeling is designed, is preferably 80 g / 25 mm or less, and more preferably 30 g / 25 mm or less. If the adhesive strength after the heat treatment exceeds 80 g / 25 mm, it becomes difficult to satisfactorily separate the adherend.

The pressure-sensitive adhesive member of the present invention comprises a heat-peelable pressure-sensitive adhesive layer provided on one or both sides of a support substrate, and the heat-peelable pressure-sensitive adhesive of the present invention described above as a heat-peelable pressure-sensitive adhesive constituting this pressure-sensitive adhesive layer. Use an adhesive. FIG. 1 is a schematic cross-sectional view illustrating one embodiment of the adhesive member of the present invention.
Has a heat-peelable pressure-sensitive adhesive layer 14 formed on one surface of a support substrate 12. The thickness of the pressure-sensitive adhesive layer provided on the support substrate is generally from 10 μm to 150 μm. The pressure-sensitive adhesive member of the present invention may be provided with a heat-peelable pressure-sensitive adhesive layer on at least one surface of a support base, and can be suitably used as a heat-peelable pressure-sensitive adhesive sheet, and its application range is wide. Purpose of use of adhesive material,
Depending on the site of use, this heat-peelable pressure-sensitive adhesive layer may be provided on both sides of the support substrate, and also provided with a heat-peelable pressure-sensitive adhesive layer on one side and a normal pressure-sensitive adhesive layer on the other side. Is also good. The support substrate used for the pressure-sensitive adhesive member of the present invention is not particularly limited as long as it has strength and durability according to the purpose, but a plastic film made of a resin material such as polyester or polyolefin, or a paper such as paper. It is preferable to use a laminated film or the like laminated on another substrate from the viewpoints of surface smoothness, uniformity of the formed pressure-sensitive adhesive layer, water resistance, and moisture resistance. The thickness of the supporting substrate is 25 μm to 25 μm.
0 μm is appropriate. When a plastic is used as the material of the base material, it is preferable to perform a corona treatment, an anchor treatment with a urethane-based or acrylic-based primer, etc., as necessary, in order to improve the adhesion to the pressure-sensitive adhesive layer. In the pressure-sensitive adhesive member of the present invention, it is preferable that the heat-peelable pressure-sensitive adhesive layer is protected by a separator using a known paper or plastic film as a base until use.

The pressure-sensitive adhesive member of the present invention can be applied to a pressure-sensitive adhesive layer having a high adhesive strength even when the surface of the adherend is rough, or when the adherend requires an adhesive property capable of firmly adhering the adherend. Adhesion with the body, strong adhesion is obtained, it is an adhesive member that can be easily peeled off by heat treatment when it is no longer required to be used, such as after use, and the base polymer of the adhesive layer and the introduction By adjusting the composition of the functional group, the used thermal crosslinking agent, and the like, the adhesive force and the heating temperature (the temperature at which releasability is exhibited) can be set. The application field of the adhesive member of the present invention is not particularly limited. Examples of the adherend to be adhered and held and examples of use include polishing and dicing of semiconductor wafers and ceramic green sheets and the like, pattern formation of printed circuit boards and the like, liquid crystal The method includes assembling glass cells and plastic cells, transporting the cells to another place, and the like, which can be expected to be useful for speeding up and automating the manufacturing process.

[0017]

EXAMPLES The present invention will be described below in detail with reference to examples, but the present invention is not limited to these examples. (Example 1) A copolymer of 70 parts by weight of 2-ethylhexyl acrylate and 30 parts by weight of acrylate, a thermal crosslinking agent: 20 parts by weight of a blocked isocyanate (Coronate 2513, manufactured by Nippon Polyurethane Industry Co., Ltd.), and thermally expandable resin particles (Microsphere F-30D, manufactured by Matsumoto Yushi-Seiyaku Co., Ltd .: expansion temperature 130-140 ° C) 20 parts by weight, curing agent (Coronate L, manufactured by Nippon Polyurethane Industry Co., Ltd.)
One part by weight was added, 80 parts by weight of toluene was added as a solvent, and the mixture was uniformly mixed to prepare a coating solution for the heat-peelable adhesive layer. The coating liquid is applied to an anchored surface of a supporting base material obtained by anchoring a modified acrylic resin on one surface of a 100 μm-thick polyethylene terephthalate film so as to have a thickness of 50 μm after drying. After drying for minutes, an adhesive layer was formed to obtain an adhesive member.

Example 2 An adhesive member was produced in the same manner as in Example 1 except that the amount of the curing agent (Coronate L) used was changed to 3 parts by weight. (Example 3) The thermally expandable resin particles used were microsphere F-80SD (Matsumoto Yushi Seiyaku Co., Ltd .: expansion temperature 16).
Except that the temperature was changed to 0 to 170 ° C.), an adhesive member was produced in the same manner as in Example 1. (Comparative Example 1) Example 1 was repeated except that no thermal crosslinking agent was added.
In the same manner as in the above, an adhesive member was produced. (Comparative Example 2) Except that no heat-expandable resin particles were added,
An adhesive member was produced in the same manner as in Example 1.

(Evaluation of Adhesive Member) The adhesive members of Examples and Comparative Examples obtained as described above were evaluated under the following conditions. The results are shown in Table 1 below. (Measurement of adhesive strength) Stainless steel plate (SUS
304, BA finished surface), a 180 ° peel test was conducted at room temperature (25 ° C.) according to the provisions of JISZ0237, and the adhesive strength at room temperature was determined. Next, the oven temperature was set to 110 ° C. or 160 ° C., which is the designed peeling value, left for 10 minutes under the heat treatment conditions, and then the adhesive force after the heat treatment was measured in the same manner as described above.

[0020]

[Table 1]

As is clear from the results shown in Table 1, all the pressure-sensitive adhesive members of the present invention show sufficient adhesive strength at room temperature, and the adhesive strength sharply decreases after heating to the designed peeling value. Was. Further, in comparison with Examples 1 and 2, it was found that the initial adhesive force could be easily adjusted by changing additives such as a curing agent. It has been found that the peel temperature can be controlled by selecting the expansion temperature. In addition, when Examples 1 and 2 in which the designed peel value was 110 ° C. were further heated to 160 ° C. beyond the designed peel value, a slight increase in the adhesive strength was observed, but it was found that the peelability was not significantly impaired. Did not. This phenomenon is considered to be due to the influence of the re-shrinkage of the thermally expanded particles and the softening of the base polymer due to heating.

[0022]

The heat-peelable pressure-sensitive adhesive of the present invention can firmly adhere to an adherend at room temperature, and its adhesiveness is stable for a long period of time. It has the advantage that the force is reduced and the adherend can be easily peeled off. Further, the pressure-sensitive adhesive member of the present invention using the heat-peelable pressure-sensitive adhesive, the stable fixing of the adherend at room temperature,
This has the effect of achieving both easy peelability after heat treatment.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view showing one embodiment of the adhesive member of the present invention.

[Explanation of symbols]

 10 adhesive member 12 support base material 14 heat-peelable adhesive

Continued on the front page F term (reference) 4J004 AA10 AA13 AA14 AA17 AB01 AC03 CA04 CA06 CC02 CC03 EA05 FA04 FA08 4J040 DF041 EC002 EF181 EF331 GA05 GA07 GA11 GA20 GA22 HC16 HC25 JA09 JA10 JB02 JB09 KA02 KA03 KA16 LA06 PA22

Claims (5)

[Claims] 1. A polymer containing an acrylic acid ester monomer as a constituent unit or a copolymer of the monomer with another unsaturated monomer copolymerizable with the monomer, and having a reactive functional group on a side chain thereof. 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, and 10 to 50 parts by weight of heat-foamable fine particles, based on 100 parts by weight of the base polymer. A heat-peelable pressure-sensitive adhesive characterized by the following. 2. The method according to claim 1, wherein a reactive functional group present on a side chain of the base polymer and a thermally reactive functional group of the crosslinking agent cause a three-dimensional crosslinking reaction by heating. The heat-peelable pressure-sensitive adhesive as described in the above. 3. The heat-peelable pressure-sensitive adhesive according to claim 1, wherein the heat-expandable fine particles are microencapsulated fine particles. 4. A 180 ° peel adhesion to a stainless steel plate at 25 ° C. (peeling speed: 300 mm / min.)
The thermal peeling according to any one of claims 1 to 3, wherein the adhesive strength is 800 g / 25 mm or more, and the adhesive strength can be reduced to 80 g / 25 mm or less by heating to a peeling design temperature. Adhesive. 5. A pressure-sensitive adhesive member, wherein a pressure-sensitive adhesive layer containing the heat-peelable pressure-sensitive adhesive according to any one of claims 1 to 4 is formed on one or both surfaces of a support. .