JP2986956B2 - Adhesive sheet - Google Patents

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 sheet whose adhesive force changes when a certain temperature is applied after being adhered to an adherend.

[0002]

2. Description of the Related Art Conventionally, general-purpose adhesives (acrylic,
An adhesive sheet obtained by applying a rubber-based material on the surface of a base material sheet is known, and since it can be peeled off as needed after it has been once adhered, it can be used for temporary bonding (for temporary fixing) or the like. It is used for various applications such as simple bonding. In recent years, pressure-sensitive adhesive sheets have been used industrially for processes such as manufacturing and assembling, and as such pressure-sensitive adhesive sheets for processes, for example, when cutting or polishing a silicon wafer into chips in a semiconductor manufacturing process, There are known a dicing tape used for temporarily fixing the wafer, a masking tape used for masking a non-painted portion at the time of coating, and a protect film for protecting the surface until used. Since these adhesive sheets are required to be adhered to an adherend at the time of use and have sufficient adhesive strength and to be easily peeled (low peeling force) after use, they are made of a conventional general-purpose adhesive. Since the pressure-sensitive adhesive sheet cannot meet such demands, a pressure-sensitive adhesive sheet improved so as to change the adhesive strength has been proposed. As the pressure-sensitive adhesive sheet having the above-mentioned release force, 1) an intermediate layer made of an ethylene-based copolymer containing an anionic surfactant is formed between a base material layer made of a plastic film or the like and a general-purpose pressure-sensitive adhesive layer. When the adhesive sheet is formed and peeled off after being adhered to the adherend, the surfactant is diffused into the adhesive layer by heating to about 70 ° C. or more, and the peeling is performed by reducing the adhesive force of the release sheet. What makes it easier (Japanese Patent Publication No. 31798). 2) On the surface of the base sheet, apply a blended resin obtained by mixing a general-purpose acrylic pressure-sensitive adhesive and an ionizing radiation-curable resin such as urethane acrylate to form a pressure-sensitive adhesive layer. When peeling after adhesion, the adhesive layer is irradiated with ionizing radiation such as ultraviolet rays to crosslink the ionizing radiation-curable resin of the adhesive layer, and the adhesive layer is formed into a three-dimensional network structure to reduce the adhesive strength. (For example, Japanese Patent Application Laid-Open Nos.
28572).

[0003]

However, when the pressure-sensitive adhesive sheet using the surfactant of the above 1) is heated at the time of peeling, it takes time for the surfactant to transfer from the intermediate layer to the pressure-sensitive adhesive layer, The heating conditions vary depending on the type of the adhesive, the coating thickness, and the like, and there is a problem that the surfactant adheres to the surface of the adherend after peeling and contaminates the adherend. Further, in the pressure-sensitive adhesive sheet in which the pressure-sensitive adhesive layer is formed into a three-dimensional network structure by the irradiation of ionizing radiation in 2), the state of the pressure-sensitive adhesive layer after the irradiation of the ionizing radiation is not three-dimensional, and the adhesive strength changes. There is a problem that the adhesive sheet itself cannot be used in a place where it is exposed to ultraviolet rays or the like before being attached to an adherend and peeled off. It has to be stored in a place where it is not exposed to ionizing radiation, and there are many restrictions on the storage location and conditions, and the sheet itself is expensive. Further, in the conventional pressure-sensitive adhesive sheets 1) and 2), the change in the adhesive strength is such that the adhesive strength is strong at the initial stage of bonding, but weakens by some processing at the time of peeling. The adhesion became strong later only by applying a simple treatment, and a pressure-sensitive adhesive sheet having good storage stability could not be obtained. The present invention is intended to solve the above-mentioned drawbacks of the prior art, and the adhesive sheet changes its adhesive force by a simple operation after sticking to an adherend, makes it easy to peel off, and is easy to store and use. The purpose is to provide.

[0004]

According to the present invention, (1) a shape memory resin film made of a shape memory resin and an adhesive layer are laminated, and the specific surface area of the primary shape is 2 in the shape memory resin film. The shaping is performed so that the specific surface area is smaller than the specific surface area of the shape of the next shaping, and when the film is reheated, the shape of the first shaping stored in the film is recovered and the adhesive strength is reduced. (2) a pressure-sensitive adhesive sheet in which a shape memory resin film made of a shape memory resin and a pressure-sensitive adhesive layer are laminated, wherein a base material sheet is laminated on the shape memory resin film side; The resin film is shaped so that the specific surface area of the primary shaping shape is smaller than the specific surface area of the secondary shaping shape, and the film is memorized when reheated. Recovers shape and reduces adhesive strength Adhesive sheet, which is characterized by being configured to be one that summarized as.

[0005]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to the drawings. The drawings show one embodiment of the present invention, FIG. 1 shows one example of the pressure-sensitive adhesive sheet of the present invention, and FIG. 2 shows another example of the pressure-sensitive adhesive sheet of the present invention. As shown in FIG. 1, the pressure-sensitive adhesive sheet 1 of the present invention has a configuration including at least a shape memory resin film 2 made of a shape memory resin and a pressure-sensitive adhesive layer 3. Further, as shown in FIG. 2, the pressure-sensitive adhesive sheet of the present invention may have a configuration in which a base sheet 4 is laminated on the shape memory resin film 2 side. The pressure-sensitive adhesive sheet 1 of the present invention is greatly characterized in that it has a layer made of a shape memory resin below the pressure-sensitive adhesive layer 3 as shown in FIGS.

In general, the shape memory resin referred to in the present invention is a stationary phase that prevents the fluidity of the resin and fixes the primary shape, and a softening and hardening that repeats softening and hardening with temperature change. It has a two-phase structure with a reversible phase that fixes its shape. The shape memory phenomenon of the resin occurs in the following steps. (1) Fixation of primary shaping The shape memory resin is melted at a melting temperature or higher at which both the stationary phase and the reversible phase are in a softened state, subjected to primary shaping, and then cooled until both of the above phases are in a hardened state. I do. (2) Fixation of the secondary shaping After the secondary shaping is performed by raising the temperature to a temperature not lower than the deformation temperature and not higher than the melting temperature at which only the reversible phase is in a softened state, the two phases are again in a hardened state. Cool down to (3) Shape memory recovery When the temperature is raised to a temperature equal to or higher than the shape deformation temperature at which only the reversible phase becomes a softened state and equal to or lower than the melting temperature, the shape of the secondary shaping is released, and the stored shape of the primary shaping is restored. To recover. The internal mechanism of the stationary phase and the reversible phase differs depending on the type of the shape memory resin. Examples of the internal mechanism of the stationary phase include entanglement between polymer chains, chemical crosslinking, crystal formation / melting,
Examples of the internal mechanism of the reversible phase include freezing of chain motion due to glass transition, formation and melting of crystals, and formation and melting of a phase structure.

Specific examples of the shape memory resin having such properties include styrene-butadiene copolymer, polyurethane, polynorbornene, trans polyisoprene,
Polyolefin, fluorine-containing resin, polycaprolactone,
Resins such as polyamide are exemplified. Among them, styrene-butadiene copolymer, polyurethane, polynorbornene, trans-polyisoprene, and the like are preferred resins, as shown below.

As a preferred shape memory resin, 1) a styrene-butadiene copolymer resin is a hybrid polymer comprising a polystyrene unit and a crystalline polybutadiene unit. That is, this resin is subjected to primary shaping using a structure in which a high melting point crystal part of a polystyrene unit is used as a stationary phase, and is subjected to secondary shaping using a structure in which a low melting point crystal part of a polybutadiene unit is used as a reversible phase. And recovery is possible. As such a resin, for example, a commercially available “Asmer” manufactured by Asahi Kasei Corporation can be used. 2) The polyurethane resin has a glass transition in the range of −30 to + 70 ° C. obtained by controlling the ratio of hard segments and soft segments of a thermoplastic polyurethane resin obtained by chain-extending and polymerizing diisocyanate and polyol. It is a polymer having a point and an elastic modulus ratio before and after the glass transition point is arbitrarily set in the range of 20 to 180.
Above the glass transition point, the molecular chain is crosslinked or partially crystallized to restrict the molecular motion and exhibit rubber elasticity.In this state, stress is applied to deform and the molecular chain is oriented, and the temperature is reduced to the glass transition temperature or less. When the second-order immobilization is fixed by fixing the molecular chains that have been oriented in this way, and the glass transition point is exceeded again, the orientation of the molecular chains is released and the original shape is restored.
As such resins, for example, commercially available products such as "MM-2500", "MM-3500", and "MM-4" manufactured by Mitsubishi Heavy Industries, Ltd.
500 "and" MM-5500 ". 3) trans-polyisoprene has a melting point of 67 ° C. and a crystallinity of 40%.
It is a resin that is the following crystalline polymer and that can be crosslinked with sulfur or peroxide. In this resin, a stationary phase is formed by the cross-linking of the polydiene double bond, and a reversible phase of softening and curing is formed by the crystal part. As such a resin, for example, “trans polyisoprene (TPI)” manufactured by Kuraray Co., Ltd. is a commercially available product. And 4) a polynorbornene-based resin based on a polymer having a molecular weight of about 3,000,000 obtained by ring-opening polymerization of cyclopentadiene monomer and ethylene. This resin is a resin capable of performing primary shaping using the entanglement of the ultrahigh molecular weight polymer as a stationary phase and performing secondary shaping and recovery by utilizing the chain motion due to the glass transition of polynorbornene. As such a resin, for example, “N” manufactured by Zeon Corporation
ORSOREX ".

In order to form the shape memory resin film 2,
First, the above resin is melted and extruded or formed into a sheet by using a known thermoplastic resin film forming method, such as dissolving in an appropriate solvent and casting on the surface of the substrate to be coated. Formed. Next, the above-mentioned sheet is heat-molded to a melting temperature or higher to perform primary shaping into an arbitrary shape, and then cooled until the stationary phase and the reversible phase are in a hardened state to fix the shape of the primary shaping. . In the primary shaping, the surface of the substrate to be coated may be formed into an arbitrary shape such as an uneven surface or a mirror surface at the time of casting, and the primary shaping and sheeting of the shape memory resin itself may be simultaneously performed. . Then, it is heated to a temperature equal to or higher than the deformation temperature at which only the reversible phase is softened and equal to or lower than the melting temperature, subjected to a desired secondary shaping, and then cooled again to harden the shape of the secondary shaping. A shape memory resin film in which the shape is stored can be obtained. The temperatures of the primary shaping and the secondary shaping can be appropriately selected according to the type of the shape memory resin to be used. The shape memory resin preferably has a relationship of room temperature <shape deformation temperature (second molding temperature) <shape recovery temperature <melting temperature (primary molding temperature).

The above-mentioned melting temperature is a temperature at which the stationary phase of the resin is brought into a molten state, and the shape deformation temperature is a temperature at which the reversible phase of softening and curing of the resin is softened. Specifically, for example, when the styrene-butadiene copolymer resin is used as the shape memory resin, the melting temperature is about 120 ° C. When the temperature is higher than this, both the stationary phase and the reversible phase are in a molten state. It can be molded into a predetermined shape in this state, and further cooled to room temperature, whereby both the stationary phase and the reversible phase can be solidified and the shape can be fixed (first-stage fixing). The shape deformation temperature is 60 ° C. to 80 ° C. When heated to this temperature, only the reversible phase is melted (the stationary phase is not melted).
When the temperature is cooled to not more than ° C., the reversible phase is hardened and the shape can be fixed (fixing of the second shaping). Further, the recovery temperature for reproducing the memory shape (the shape of the primary shaping) is 60 to 90 ° C., and when heated to this temperature, the reversible phase crystal temporarily fixes the deformation during the secondary shaping. The portion is melted, and the shape of the primary shaping can be restored.

FIGS. 3 and 4 are longitudinal sectional views showing an example of use of the pressure-sensitive adhesive sheet of the present invention, in which the release sheet 5 of the pressure-sensitive adhesive sheet shown in FIG. 1 is peeled off and adhered to an adherend 6. The shape of the primary shaping and the shape of the secondary shaping used in the pressure-sensitive adhesive sheet of the present invention are the same as those of the shape memory resin film 2 made of a shape memory resin.
The film 2 is shaped so that the specific surface area of the primary shaping shape (FIG. 4) is smaller than the specific surface area of the secondary shaping shape (FIG. 3). It is formed so as to recover the shape of the primary shaping that has been performed (FIG. 3) and reduce the adhesive strength. When formed as described above, when the pressure-sensitive adhesive sheet 1 is heated to a temperature higher than the temperature of the secondary shaping to recover the memory shape of the primary shaping, the pressure-sensitive adhesive layer 3 laminated on the film 2 becomes And the contact area with the adherend becomes smaller. Therefore, the adhesive tape 1 can be easily separated from the adherend 6 only by heating. In this case, the specific surface area refers to a contact area per a fixed area when the shape memory resin film 2 is brought into contact with a smooth surface. In order to form the shape smaller than the specific surface area of the shape,
The surface may be formed in an uneven shape by embossing or the like.

[0012]

As the resin forming the pressure-sensitive adhesive layer 3 of the pressure-sensitive adhesive sheet 1 of the present invention, any of general acrylic, rubber-based, silicone-based pressure-sensitive adhesives used in conventionally known pressure-sensitive adhesive sheets and the like can be used. Any of a solvent type, an emulsion type and the like can be used, and an ionizing radiation curable resin can also be used. Specific materials for the resin forming the pressure-sensitive adhesive layer include, for example, rubber resins such as polyisoprene rubber, acrylic resins such as (meth) acrylate resins, polyvinyl ether resins,
Suitable tackifier for any adhesive such as polyvinyl acetate resin, vinyl chloride vinyl acetate copolymer resin, polystyrene resin, polyester resin, polyamide resin, polychlorinated olefin resin, polyvinyl butyral resin, etc. For example, rosin, dammar, polymerized rosin, partially hydrogenated rosin, ester rosin, polyterpene resin, modified terpene, petroleum resin, cyclopentadiene resin,
Phenolic resin, styrene resin, xylene resin,
Phenolic resin, styrene resin, xylene resin,
It is a resin to which an appropriate amount of a coumarone-indene resin or the like is added, and further, if necessary, a softener, a filler, an antioxidant, and the like can be added. To such an adhesive, in the case of a solvent type, an organic solvent or the like is added as necessary to adjust the viscosity, and for example, a direct coating method such as a roll coating, a die coating, a knife coating, a gravure coating, etc. It is possible to form a pressure-sensitive adhesive layer by appropriately selecting in consideration of heat resistance, ionizing radiation resistance of the base sheet, coating thickness, smoothness, paint composition, and the like, using a coating method, a transfer coating method, or the like. it can. The pressure-sensitive adhesive layer thus formed may have any thickness, but is generally desirably formed to a thickness of about 10 to 50 μm.

The material of the base sheet 4 is not particularly limited.
For example, the material of the base sheet is paper such as thin paper, bleached kraft paper, titanium paper, linter paper, paperboard, gypsum board paper, polyethylene, polypropylene, polyvinyl chloride, polyvinylidene chloride, polyvinyl alcohol, polyethylene terephthalate, polycarbonate, nylon , Polystyrene, ethylene-vinyl acetate copolymer, ethylene-vinyl alcohol copolymer, ionomer, thermoplastic resin film such as (meth) acrylic polymer, phenol resin, urea resin, unsaturated polyester resin, urethane resin, epoxy resin , A sheet (sheet) of thermosetting resin such as melamine resin, a metal foil or sheet of iron, aluminum, copper, etc., a metal plate such as galvanized steel sheet, a wood base material such as wood,
Gypsum base material such as gypsum board, fiber cement board such as pulp cement board, cement board such as lightweight foam concrete board,
Examples include a slate plate, a ceramic plate such as an enamel, and a composite of each of the above substrates.

In the pressure-sensitive adhesive sheet of the present invention, as shown in FIG. 1, a release sheet 5 can be laminated on the surface of the pressure-sensitive adhesive layer.
The material of the release sheet 5 is not particularly limited as long as it has releasability from the pressure-sensitive adhesive layer, and is usually the above-mentioned base sheet or a plastic sheet or paper obtained by releasing the surface of the base sheet. Is used. In the release treatment, a coating film layer is formed by applying a fluorine resin, silicone, melamine, polyolefin, ionizing radiation curable resin, or the like. When the release sheet 5 is not used, for example, when the pressure-sensitive adhesive sheet is continuously formed in a roll shape, the release is performed on the back surface of the shape memory resin film 2 (the base sheet 4 in FIG. 2) as described above. What is necessary is just to perform a process and to form it so that it can be peeled off from the adhesive layer 3.

Although not particularly shown in the pressure-sensitive adhesive sheet of the present invention, the surface of the pressure-sensitive adhesive layer and the shape memory resin film may be subjected to primer application or surface treatment in order to improve the adhesive strength.

Next, a method for forming the pressure-sensitive adhesive sheet of the present invention will be described. When the pressure-sensitive adhesive sheet of FIG. 1 is formed, the shape memory resin film 2 is subjected to primary shaping and secondary shaping as described above to form a predetermined shape. Then, an adhesive layer 3 is formed on the surface of the film 2 and a release sheet 5 is laminated.
Alternatively, after forming the pressure-sensitive adhesive layer 3 on the surface of the release sheet 5, the film 2 formed in a predetermined shape may be laminated so that the pressure-sensitive adhesive layer 3 and the film 2 are in contact with each other. When the pressure-sensitive adhesive sheet shown in FIG.
Next molding is performed to form a predetermined shape. Then, after laminating the film 2 with the base sheet 4, the pressure-sensitive adhesive layer 3 and the release layer 5 are laminated on the film 2 side as described above to obtain the pressure-sensitive adhesive sheet 1.

Since the pressure-sensitive adhesive sheet of the present invention can easily change the peeling force only by heating after adhering to an adherend, it can be used as a pressure-sensitive adhesive tape for a process, for example, in a semiconductor manufacturing process or a multilayer ceramic capacitor manufacturing process. It can be optimally used for a dicing tape used in a dicing step, a masking tape for painting, a protective film, and the like.

Hereinafter, the present invention will be described in more detail with reference to specific examples. Example 1 A resin solution obtained by dissolving 30 parts by weight of a shape-memory resin (Asmar, manufactured by Asahi Kasei Corporation) composed of a styrene-butadiene copolymer in 100 parts by weight of toluene was applied to a thickness of 1 by a casting method.
A 00 μm shape memory resin film was prepared. Next, the film was embossed at a surface temperature of 130 ° C. to form irregularities on the surface, and then cooled. The embossed film was pressed at a surface temperature of 80 ° C. using a mirror roll to smooth the film surface. On the other hand, a pressure-sensitive adhesive (SK Dyne, manufactured by Soken Chemical Co., Ltd.) was applied to the surface of a release film (manufactured by Toyo Metallizing: Therapy) using a comma coat method, and then dried at 110 ° C. for 2 minutes (coat thickness,
15 μm dry). This release film and the above-mentioned shape memory resin film were laminated so that the pressure-sensitive adhesive layer was in contact therewith to obtain a pressure-sensitive adhesive sheet. The obtained pressure-sensitive adhesive sheet was subjected to JISZ02
A peel test was performed in accordance with No.37. A stainless steel plate is used as an adherend, two stainless steel plates are prepared, and a pressure-sensitive adhesive sheet is adhered to each of them. After that, one of them is subjected to a peeling test as it is, and the other is heated at 80 ° C. for 5 minutes. After that, a peeling test was performed. As a result, the unheated adhesive sheet showed an adhesive force of 300 g / 25 mm, and the other heated adhesive sheet showed
It showed an adhesive strength of 0 g / 25 mm. That is, it was confirmed that the above-mentioned peeling sheet was easily peeled off due to a decrease in adhesive strength when heated.

Example 2 A 50-μm-thick PET film (T60, manufactured by Toray Industries, Inc.) was coated with 30 parts by weight of a shape-memory resin made of a styrene-butadiene copolymer (Asmer, manufactured by Asahi Kasei) in toluene 10
A resin solution dissolved in 0 parts by weight was applied by a comma coat method, dried at 80 ° C. for 1 minute to form a shape memory resin film having a thickness of 30 μm, and then cooled. Next, the film was embossed at a surface temperature of 130 ° C. to form irregularities on the intermediate layer on the surface. The embossed film is pressed using a mirror roll at a surface temperature of 80 ° C.
The intermediate layer on the film surface was smoothed. On the other hand, a pressure-sensitive adhesive (SK Dyne, manufactured by Soken Chemical Co., Ltd.) was applied to the surface of a release film (manufactured by Toyo Metallizing: Therapy) using a comma coat method, and then dried at 110 ° C. for 2 minutes (coat thickness,
15 μm dry). This release film and the above PET
The film was laminated so that the shape memory resin film and the pressure-sensitive adhesive layer were in contact with each other to obtain a pressure-sensitive adhesive sheet. The obtained pressure-sensitive adhesive sheet was subjected to a peel test in accordance with JISZ0237. A stainless steel plate is used as an adherend, two stainless steel plates are prepared, and a pressure-sensitive adhesive sheet is adhered to each of them. After that, one of them is subjected to a peeling test as it is, and the other is heated at 80 ° C. for 5 minutes. After that, a peeling test was performed. As a result, the unheated adhesive sheet showed an adhesive force of 500 g / 25 mm, and the other heated adhesive sheet showed an adhesive force of 50 g / 25 mm. That is, it was confirmed that the above-mentioned peeling sheet was easily peeled off due to a decrease in adhesive strength when heated.

[0020]

As described above, the pressure-sensitive adhesive sheet of the present invention employs a structure in which a shape memory resin film made of a shape memory resin and a pressure-sensitive adhesive layer are laminated, so that the lower layer of the pressure-sensitive adhesive layer can be arbitrarily heated by heating. It is possible to change the shape, and since the pressure-sensitive adhesive layer deforms following the shape of the shape memory resin film, it is possible to change the contact area between the pressure-sensitive adhesive sheet after application and the adherend. Yes, the peeling force can be arbitrarily changed by a simple operation of only heating. When the shape memory resin film is shaped such that the specific surface area of the primary shaping shape is smaller than the specific surface area of the secondary shaping shape, the adhesive force may be significantly reduced by heating. It has the effect that it can be easily peeled off. Compared to a pressure-sensitive adhesive sheet using a conventional surfactant or a pressure-sensitive adhesive sheet in which an ionizing radiation-curable resin is mixed into a pressure-sensitive adhesive layer, the coating after peeling is A pressure-sensitive adhesive sheet free from the danger that the surfactant adheres to the surface of the adherend and contaminates the adherend, variations in the adhesive force, and restrictions on the place of use can be obtained. In addition, by laminating the base material sheet on the shape memory resin film side, an arbitrary material can be selected as the material used for the base material sheet, so that the range of material selection can be widened and the amount of shape memory resin used can be reduced. This has the effect of reducing the material cost of the pressure-sensitive adhesive sheet.

[Brief description of the drawings]

FIG. 1 is a partial longitudinal sectional view showing one example of the pressure-sensitive adhesive sheet of the present invention.

FIG. 2 is a partial longitudinal sectional view showing another example of the pressure-sensitive adhesive sheet of the present invention.

FIG. 3 is a partial longitudinal sectional view showing a usage example of the pressure-sensitive adhesive sheet of the present invention.

FIG. 4 is a partial longitudinal sectional view showing a usage example of the pressure-sensitive adhesive sheet of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Adhesive sheet 2 Shape memory resin film 3 Adhesive layer 4 Base sheet

Claims (2)

(57) [Claims] 1. A shape memory resin film made of a shape memory resin and an adhesive layer are laminated, and the shape memory resin film is
The specific surface area of the primary shaping shape is the specific surface area of the secondary shaping shape
Shape so that it is smaller than
Recover the shape of the primary imprint stored in the film
A pressure-sensitive adhesive sheet, wherein the pressure-sensitive adhesive sheet is configured to have a reduced adhesion. 2. An adhesive sheet in which a shape memory resin film made of a shape memory resin and an adhesive layer are laminated,
The substrate sheet is laminated on the shape-memory resin film side, the shape
The specific surface area of the primary imprinted shape is secondary to the memory resin film
The shaping is performed so that it is smaller than the specific surface area of the shaping shape.
And when the film is reheated,
It is configured to recover the shape of the shape and reduce the adhesive strength
Pressure-sensitive adhesive sheet, characterized in that there.