JP4647896B2 - Adhesive tape - Google Patents

Description

The present invention relates to a pressure-sensitive adhesive tape that can be peeled off from an adherend by giving a stimulus even when left for a certain period after bonding.

The performance required for adhesive tapes varies depending on the application, but depending on the application, it can be firmly adhered and fixed to the adherend as long as necessary, but it must be easily peeled off after use. There is.
For example, in a manufacturing process of an IC chip, when a thick film wafer cut from a high-purity silicon single crystal or the like is ground to a predetermined thickness to form a thin film wafer, the thick film wafer is supported using a double-sided adhesive tape. It has been proposed to work efficiently by adhering to a plate and reinforcing it. The double-sided pressure-sensitive adhesive tape at this time is required to be firmly peeled off during the grinding process, and peeled off from the support plate without damaging the thin film wafer obtained after the grinding process.

As a method for peeling off the adhesive tape, for example, it is conceivable to peel it off by applying a physical force. However, this method may cause serious damage when the adherend is soft. Moreover, the method of peeling an adhesive tape using the solvent which can melt | dissolve an adhesive is also considered. However, this method cannot be used when the adherend is attacked by a solvent. As described above, the pressure-sensitive adhesive tape once used for adhesion has a problem that it is difficult to peel off the adherend without damaging the adherend as the adhesive strength is stronger.

As a result of intensive studies, the present inventors have so far used the pressure-sensitive adhesive tape having a pressure-sensitive adhesive layer containing a gas generating agent that generates gas by stimulation, and the generated gas peels at least a part of the adhesive surface. It was found that the adhesive tape can be easily peeled off from the adherend. Further, at this time, if a large amount of gas is generated in a short time, the adherend is spontaneously peeled from the pressure-sensitive adhesive layer, and the peeled adherend is in a state as if it floated from the pressure-sensitive adhesive layer. (Hereinafter also referred to as self-peeling). Such self-peeling can be suitably used for adhesion of adherends that are extremely fragile, such as thin film wafers ground to an extremely thin thickness.
However, since the adhesion between the pressure-sensitive adhesive layer and the adherend is not necessarily uniform, peeling by the gas generated from the pressure-sensitive adhesive layer tends to proceed in advance from a portion having a relatively weak adhesive force. At this time, if the edge of the adhesive surface has peeled off first, the generated gas leaks from the peeled edge, and sufficient peeling pressure cannot be obtained, resulting in an unpeeled part. In some cases, self-peeling was impossible. Such non-uniform peeling tended to become prominent particularly when adhesion was promoted after standing for a certain period of time after bonding.

An object of the present invention is to provide a pressure-sensitive adhesive tape that can be peeled off from an adherend by giving a stimulus even when left for a certain period of time after bonding.

The present invention 1 is an adhesive tape in which an adhesive layer containing a gas generating agent that generates gas by stimulation is formed on at least one surface of a substrate, and the substrate is on the surface of the adhesive layer side. Embossing with a convex portion height of 3 μm or more is applied, the pressure-sensitive adhesive layer contains a cross-linking component that cross-links upon stimulation , and the gas generating agent dissolves in the pressure-sensitive adhesive layer. It is an adhesive tape.

The present invention 2 is an adhesive tape in which an adhesive layer containing a gas generating agent that generates gas by stimulation is formed on at least one side of a substrate, wherein the adhesive layer has a crosslinking component that is crosslinked by stimulation. The pressure-sensitive adhesive tape contains microbeads having a diameter of 3 μm or more.

The present invention 3 is an adhesive tape in which an adhesive layer containing a gas generating agent that generates gas by stimulation is formed on at least one side of a substrate, and the adhesive layer has a height of a convex portion on the surface. Is an adhesive tape that is embossed with a thickness of 3 μm or more.
The pressure-sensitive adhesive tape of the present invention may be a single-sided pressure-sensitive adhesive tape in which a pressure-sensitive adhesive layer is formed only on one side of a substrate, or a double-sided pressure-sensitive adhesive tape in which a pressure-sensitive adhesive layer is formed on both sides of a substrate. Good.
The present invention is described in detail below.

As a result of intensive studies, the present inventors have found that the adhesive tape having a pressure-sensitive adhesive layer containing a gas generating agent that generates a gas upon stimulation is bonded to the adherend prior to generating the gas upon peeling. If unevenness is formed on almost the entire surface of the pressure-sensitive adhesive layer, gas is generated starting from the recesses, peeling of the adhesive surface begins, the peeling progresses uniformly, and an unpeeled portion remains. The present invention has been completed by finding that self-peeling can be performed without any problem.

As a method for forming irregularities on the surface of the pressure-sensitive adhesive layer as described above, a method utilizing the curing shrinkage of the pressure-sensitive adhesive layer can be mentioned. That is, if a cross-linking component that is cross-linked by stimulation is added to the pressure-sensitive adhesive layer, the cross-linking component in the pressure-sensitive adhesive layer causes a cross-linking reaction due to stimulation, and the entire pressure-sensitive adhesive layer is cured and contracted accordingly. Here, 1) The surface of the base material is embossed in advance to form a concavo-convex pattern, or 2) If an additive such as microbeads is blended in the adhesive layer, these concavo-convex patterns Or an additive becomes a shaping material, and unevenness according to the shape and size of the shaping material appears on the surface of the pressure-sensitive adhesive layer due to curing shrinkage of the pressure-sensitive adhesive layer.
For simplicity, 3) a method of embossing the surface of the pressure-sensitive adhesive layer in advance is also mentioned. The embossing effect remains on the surface of the pressure-sensitive adhesive layer for a relatively short period of time after bonding the pressure-sensitive adhesive tape and the adherend, and this unevenness is again formed on the surface of the pressure-sensitive adhesive layer during peeling. appear. However, after bonding, this effect is lost as it is stored for a long time.
These methods may be used independently and may use 2 or more types together.

The present invention 1 realizes self-peeling by forming irregularities on the surface of the pressure-sensitive adhesive layer of the pressure-sensitive adhesive tape at the time of peeling by the method 1) described above, and generates gas by stimulation on at least one side of the substrate. The pressure-sensitive adhesive tape is formed with a pressure-sensitive adhesive layer containing a gas generating agent, and the base material is embossed with a convex portion height of 3 μm or more on the surface on the pressure-sensitive adhesive layer side, The pressure-sensitive adhesive layer is a pressure-sensitive adhesive tape containing a crosslinking component that is crosslinked by stimulation.

The adhesive tape of this invention 1 has a base material and an adhesive layer.
Although it does not specifically limit as said base material, When the irritation | stimulation which generates gas from the said gas generating agent is irritation | stimulation by light, it is preferable that it is what permeate | transmits or passes light, for example, an acryl, an olefin, a polycarbonate , Vinyl chloride, ABS, polyethylene terephthalate (PET), nylon, urethane, a sheet made of transparent resin such as polyimide, a sheet having a network structure, a sheet with holes, and the like.

In this invention 1, the surface at the side of the adhesive layer of the said base material is embossed. In the present specification, embossing refers to providing a surface with a concavo-convex pattern.
The uneven pattern imparted to the surface of the base material by embossing is, for example, a random pattern that is formed over the entire surface of the base material, and almost all the convex portions that are formed are continuous at intervals of about several hundred μm. An uneven pattern, a regular uneven pattern, etc. are mentioned. Among them, a concavo-convex pattern having a regular concavo-convex pattern in which the heights of the convex portions are uniform and the depths of the concave portions are uniform is preferable. Examples of such a concavo-convex pattern include a concavo-convex pattern in which dots, straight lines, arcs and the like are continuously arranged at intervals of about several hundred μm over the entire surface.

The height of the convex part of the concavo-convex pattern provided on the surface of the substrate by the embossing is 3 μm or more. If the thickness is less than 3 μm, the surface of the pressure-sensitive adhesive layer is not sufficiently uneven so as to be a starting point for gas generation, and self-peeling cannot be realized. Preferably it is 8 micrometers or more, More preferably, it is 10 micrometers or more.

The pressure-sensitive adhesive layer contains a gas generating agent that generates gas upon stimulation.
Examples of the stimulus for generating gas from the gas generating agent include stimulation by light, heat, and ultrasonic waves. Of these, stimulation by light or heat is preferred. Examples of the light include ultraviolet light and visible light. When light stimulation is used as the stimulation, the pressure-sensitive adhesive layer containing the gas generating agent is preferably capable of transmitting or passing light.
Although it does not specifically limit as a gas generating agent which generate | occur | produces gas by the said irritation | stimulation, For example, an azo compound and an azide compound are used suitably.

Examples of the azo compound include 2,2′-azobis (N-cyclohexyl-2-methylpropionamide), 2,2′-azobis [N- (2-methylpropyl) -2-methylpropionamide], 2 , 2′-azobis (N-butyl-2-methylpropionamide), 2,2′-azobis [N- (2-methylethyl) -2-methylpropionamide], 2,2′-azobis (N-hexyl) -2-methylpropionamide), 2,2′-azobis (N-propyl-2-methylpropionamide), 2,2′-azobis (N-ethyl-2-methylpropionamide), 2,2′-azobis {2-Methyl-N- [1,1-bis (hydroxymethyl) -2-hydroxyethyl] propionamide}, 2,2′-azobis {2-methyl-N- [2- ( -Hydroxybutyl)] propionamide}, 2,2′-azobis [2-methyl-N- (2-hydroxyethyl) propionamide], 2,2′-azobis [N- (2-propenyl) -2-methyl Propionamide], 2,2′-azobis [2- (5-methyl-2-imidazolin-2-yl) propane] dihydrochloride, 2,2′-azobis [2- (2-imidazolin-2-yl) propane] Dihydrochloride, 2,2′-azobis [2- (2-imidazolin-2-yl) propane] disulfate dihydrolate, 2,2′-azobis [2- (3,4,5,6-tetrahydro Pyrimidin-2-yl) propane] dihydrochloride, 2,2′-azobis {2- [1- (2-hydroxyethyl) -2-imidazolin-2-yl] propyl Pan} dihydrochloride, 2,2′-azobis [2- (2-imidazolin-2-yl) propane], 2,2′-azobis (2-methylpropionamidine) hydrochloride, 2,2′-azobis (2 -Aminopropane) dihydrochloride, 2,2'-azobis [N- (2-carboxyacyl) -2-methyl-propionamidine], 2,2'-azobis {2- [N- (2-carboxyethyl) Amidine] propane}, 2,2′-azobis (2-methylpropionamide oxime), dimethyl 2,2′-azobis (2-methylpropionate), dimethyl 2,2′-azobisisobutyrate, 4, 4'-azobis (4-cyancarbonic acid), 4,4'-azobis (4-cyanopentanoic acid), 2,2'-azobi (2,4,4-trimethylpentane) and the like. These azo compounds generate nitrogen gas mainly by irradiating light in the ultraviolet region with a wavelength of about 365 nm.

The azo compound preferably has a 10-hour half-life temperature of 80 ° C. or higher. When the 10-hour half-life temperature is less than 80 ° C., the pressure-sensitive adhesive tape of the present invention may cause foaming when it is dried by forming a pressure-sensitive adhesive layer by casting, or a decomposition reaction may occur over time. May bleed out, or may generate gas over time and cause floating at the interface with the adherend. If the 10-hour half-life temperature is 80 ° C. or higher, the heat resistance is excellent, and therefore, use at a high temperature and stable storage are possible.

Examples of the azo compound having a 10-hour half-life temperature of 80 ° C. or higher include an azoamide compound represented by the following general formula (1). In addition to excellent heat resistance, the azoamide compound represented by the following general formula (1) is also excellent in solubility in adhesive polymers such as an alkyl acrylate polymer to be described later. The particles may not exist as particles.

In formula (1), R ¹ and R ² each represent a lower alkyl group, and R ³ represents a saturated alkyl group having 2 or more carbon atoms. R ¹ and R ² may be the same or different.

Examples of the azoamide compound represented by the general formula (1) include 2,2′-azobis (N-cyclohexyl-2-methylpropionamide) and 2,2′-azobis [N- (2-methylpropyl). -2-methylpropionamide], 2,2′-azobis (N-butyl-2-methylpropionamide), 2,2′-azobis [N- (2-methylethyl) -2-methylpropionamide], 2 , 2′-azobis (N-hexyl-2-methylpropionamide), 2,2′-azobis (N-propyl-2-methylpropionamide), 2,2′-azobis (N-ethyl-2-methylpropionamide) Amide), 2,2′-azobis {2-methyl-N- [1,1-bis (hydroxymethyl) -2-hydroxyethyl] propionamide}, 2,2′-azobi {2-methyl-N- [2- (1-hydroxybutyl)] propionamide}, 2,2′-azobis [2-methyl-N- (2-hydroxyethyl) propionamide], 2,2′-azobis [N- (2-propenyl) -2-methylpropionamide] and the like. Among these, 2,2′-azobis (N-butyl-2-methylpropionamide) and 2,2′-azobis [N- (2-propenyl) -2-methylpropionamide] have improved solubility in solvents. It is preferably used because it is particularly excellent.

Examples of the azide compound include 3-azidomethyl-3-methyloxetane, terephthalazide, p-tert-butylbenzazide; glycidyl azide polymer obtained by ring-opening polymerization of 3-azidomethyl-3-methyloxetane, and the like. Examples thereof include a polymer having an azide group. These azide compounds generate nitrogen gas mainly by irradiating light in the ultraviolet region with a wavelength of about 365 nm.

Among these gas generating agents, the azide compound is easily decomposed even by giving an impact and releases nitrogen gas, so that there is a problem that handling is difficult. Furthermore, once the decomposition starts, the azide compound causes a chain reaction and explosively releases nitrogen gas, which cannot be controlled. Therefore, the adherend may be damaged by the explosively generated nitrogen gas. There is also a problem. Due to such problems, the amount of the azide compound used is limited, but sufficient effects may not be obtained with the limited amount used.

On the other hand, unlike the azide compound, the azo compound is extremely easy to handle because it does not generate gas upon impact. In addition, since no gas is explosively generated due to a chain reaction, the adherend is not damaged, and generation of gas can be interrupted if light irradiation is interrupted. There is also an advantage that control is possible. Therefore, it is more preferable to use an azo compound as the gas generating agent.

The gas generating agent is preferably not present as particles in the pressure-sensitive adhesive layer. In addition, in this specification, that a gas generating agent does not exist as a particle | grain means that a gas generating agent cannot be confirmed when the said adhesive layer is observed with an electron microscope. When the gas generating agent is present as particles in the pressure-sensitive adhesive layer, when light is irradiated as a gas generating stimulus, light is scattered at the particle interface, resulting in low gas generation efficiency. The surface smoothness may deteriorate.

In order to prevent the gas generating agent from being present as particles, normally, a gas generating agent that dissolves in the adhesive constituting the adhesive layer is selected, but when a gas generating agent that does not dissolve in the adhesive is selected. For example, the gas generating agent is finely dispersed in the pressure-sensitive adhesive layer by using a disperser or using a dispersing agent in combination. In order to finely disperse the gas generating agent in the pressure-sensitive adhesive layer, the gas generating agent is preferably fine particles, and these fine particles are necessary using, for example, a disperser or a kneading apparatus. Accordingly, finer fine particles are preferable. That is, it is more preferable to disperse the gas generating agent to a state where it cannot be confirmed when the pressure-sensitive adhesive layer is observed with an electron microscope.

In the pressure-sensitive adhesive tape of the present invention, the gas generated from the gas generating agent is preferably released out of the pressure-sensitive adhesive layer. Thereby, when irradiating light to the adhesion surface where the pressure-sensitive adhesive tape of the present invention is attached to the adherend, the gas generated from the gas generating agent peels off at least a part of the adhesion surface from the adherend and reduces the adhesive force. It can be easily peeled off from the adherend. At this time, it is preferable that most of the gas generated from the gas generating agent is released out of the pressure-sensitive adhesive layer. If most of the gas generated from the gas generating agent is not released to the outside of the pressure-sensitive adhesive layer, the pressure-sensitive adhesive layer is foamed entirely by the gas generated from the gas generating agent, and the effect of reducing the adhesive force is sufficient. In some cases, adhesive residue may be generated on the adherend. As long as no adhesive residue is generated on the adherend, a part of the gas generated from the gas generating agent may be dissolved in the adhesive layer or may be present as bubbles in the adhesive layer. It doesn't matter.

The pressure-sensitive adhesive constituting the pressure-sensitive adhesive layer contains a cross-linking component that cross-links upon stimulation. By including such a crosslinking component, if the crosslinking component is crosslinked prior to generating gas during peeling, the entire pressure-sensitive adhesive layer is cured and shrunk, corresponding to the uneven pattern on the surface of the substrate. Unevenness appears on the surface of the pressure-sensitive adhesive layer.
The stimulus for crosslinking the crosslinking component may be the same as or different from the stimulus for generating gas from the gas generating agent. When the stimuli are different, a stimulus for cross-linking the cross-linking component is given before giving a stimulus for generating gas from the gas generating agent at the time of peeling. Even when the stimulation is the same, gas is usually generated from the gas generating agent, and there is a time lag before it is released from the adhesive layer, so the crosslinking reaction of the crosslinking component and the curing of the adhesive layer Shrinkage precedes.

The crosslinking component is not particularly limited, and examples thereof include a radical polymerizable polyfunctional oligomer or monomer. Along with these crosslinking components, for example, if a photopolymerization initiator is blended, the crosslinking reaction of the crosslinking component can be initiated by light stimulation, and if a thermal polymerization initiator is blended, the crosslinking component is crosslinked by heat stimulation. Can be started. Furthermore, if an acrylic acid alkyl ester-based and / or methacrylic acid alkyl ester-based polymerizable polymer having a radical polymerizable unsaturated bond in the molecule is combined, a photo-curing adhesive or a thermosetting adhesive It becomes.

Such a photo-curing pressure-sensitive adhesive or a thermosetting pressure-sensitive adhesive such as a thermosetting pressure-sensitive adhesive is polymerized and cured because the entire pressure-sensitive adhesive is uniformly and rapidly polymerized and cross-linked by irradiation or heating with light. As the elastic modulus increases significantly due to, and the adhesive strength is greatly reduced, the peelability can be further improved. In addition, when gas is generated from a gas generating agent in a hard cured product, most of the generated gas is released to the outside, and the released gas peels at least part of the adhesive surface from the adherend, reducing the adhesive strength. Let

The polymerizable polymer is prepared by, for example, previously synthesizing a (meth) acrylic polymer having a functional group in the molecule (hereinafter referred to as a functional group-containing (meth) acrylic polymer) and reacting with the functional group in the molecule. It can obtain by making it react with the compound (henceforth a functional group containing unsaturated compound) which has a functional group to perform and a radically polymerizable unsaturated bond.

The functional group-containing (meth) acrylic polymer is an acrylic having an alkyl group usually in the range of 2 to 18 as a polymer having adhesiveness at room temperature, as in the case of a general (meth) acrylic polymer. By copolymerizing an acid alkyl ester and / or methacrylic acid alkyl ester as a main monomer, a functional group-containing monomer, and, if necessary, another modifying monomer copolymerizable therewith by a conventional method It is obtained. The weight average molecular weight of the functional group-containing (meth) acrylic polymer is usually about 200,000 to 2,000,000.

Examples of the functional group-containing monomer include a carboxyl group-containing monomer such as acrylic acid and methacrylic acid; a hydroxyl group-containing monomer such as hydroxyethyl acrylate and hydroxyethyl methacrylate; and an epoxy group containing glycidyl acrylate and glycidyl methacrylate. Monomers; Isocyanate group-containing monomers such as isocyanate ethyl acrylate and isocyanate ethyl methacrylate; and amino group-containing monomers such as aminoethyl acrylate and aminoethyl methacrylate.

Examples of other modifying monomers that can be copolymerized include various monomers used in general (meth) acrylic polymers such as vinyl acetate, acrylonitrile, and styrene.

The functional group-containing unsaturated compound to be reacted with the functional group-containing (meth) acrylic polymer is the same as the functional group-containing monomer described above according to the functional group of the functional group-containing (meth) acrylic polymer. it can. For example, when the functional group of the functional group-containing (meth) acrylic polymer is a carboxyl group, an epoxy group-containing monomer or an isocyanate group-containing monomer is used, and when the functional group is a hydroxyl group, an isocyanate group-containing monomer is used. When the functional group is an epoxy group, a carboxyl group-containing monomer or an amide group-containing monomer such as acrylamide is used, and when the functional group is an amino group, an epoxy group-containing monomer is used.

The polyfunctional oligomer or monomer preferably has a molecular weight of 10,000 or less, and more preferably has a molecular weight of 5000 or less so that the three-dimensional network of the pressure-sensitive adhesive layer can be efficiently formed by heating or light irradiation. And the number of radically polymerizable unsaturated bonds in the molecule is 2 to 20. Examples of such more preferred polyfunctional oligomers or monomers include trimethylolpropane triacrylate, tetramethylolmethane tetraacrylate, pentaerythritol triacrylate, pentaerythritol tetraacrylate, dipentaerythritol monohydroxypentaacrylate, dipentaerythritol hexaacrylate. Or the above-mentioned methacrylates etc. are mentioned. Other examples include 1,4-butylene glycol diacrylate, 1,6-hexanediol diacrylate, polyethylene glycol diacrylate, commercially available oligoester acrylate, and methacrylates similar to those described above. These polyfunctional oligomers or monomers may be used alone or in combination of two or more.

Examples of the photopolymerization initiator include those activated by irradiation with light having a wavelength of 250 to 800 nm. Examples of such a photopolymerization initiator include acetophenone derivative compounds such as methoxyacetophenone. Benzoin ether compounds such as benzoin propyl ether and benzoin isobutyl ether; ketal derivative compounds such as benzyl dimethyl ketal and acetophenone diethyl ketal; phosphine oxide derivative compounds; bis (η5-cyclopentadienyl) titanocene derivative compounds, benzophenone, Michler's ketone Chlorothioxanthone, todecylthioxanthone, dimethylthioxanthone, diethylthioxanthone, α-hydroxycyclohexyl phenyl ketone, 2-hydroxymethylphenyl pro Examples thereof include photo radical polymerization initiators such as bread. These photoinitiators may be used independently and 2 or more types may be used together.

Examples of the thermal polymerization initiator include those that decompose by heat and generate active radicals that initiate polymerization and curing, such as dicumyl peroxide, di-t-butyl peroxide, and t-butyl peroxybenzoale. , T-butyl hydroperoxide, benzoyl peroxide, cumene hydroperoxide, diisopropylbenzene hydroperoxide, paramentane hydroperoxide, di-t-butyl peroxide and the like. Among these, cumene hydroperoxide, paramentane hydroperoxide, di-t-butyl peroxide, and the like are preferable because of their high thermal decomposition temperature. Although it does not specifically limit as what is marketed among these thermal-polymerization initiators, For example, perbutyl D, perbutyl H, perbutyl P, permenta H (all are the products made from NOF) etc. are suitable. These thermal polymerization initiators may be used independently and 2 or more types may be used together.

In addition to the above components, the post-curing pressure-sensitive adhesive described above is variously blended with general pressure-sensitive adhesives such as isocyanate compounds, melamine compounds, and epoxy compounds as desired for the purpose of adjusting the cohesive force as pressure-sensitive adhesives You may mix | blend a polyfunctional compound suitably. Moreover, well-known additives, such as a plasticizer, resin, surfactant, wax, and a fine particle filler, can also be added.

The method for producing the pressure-sensitive adhesive tape of the present invention 1 is not particularly limited. For example, a pressure-sensitive adhesive containing the gas generating agent or the like is applied to the surface of the substrate that has been embossed. Examples of the method include coating using, for example.

The present invention 2 realizes self-peeling by forming irregularities on the surface of the pressure-sensitive adhesive layer of the pressure-sensitive adhesive tape at the time of peeling by the method 2) described above, and generates gas by stimulation on at least one side of the substrate. The pressure-sensitive adhesive tape has a pressure-sensitive adhesive layer containing a gas generating agent, and the pressure-sensitive adhesive layer is a pressure-sensitive adhesive tape containing a cross-linking component that is cross-linked by stimulation and containing microbeads having a diameter of 3 μm or more. is there.
As the gas generating agent, the pressure-sensitive adhesive constituting the pressure-sensitive adhesive layer and the like in the pressure-sensitive adhesive tape of the present invention 2, those similar to those of the pressure-sensitive adhesive tape of the present invention 1 can be used. Moreover, the thing similar to the adhesive tape of this invention 1 can be used except that it is not necessary to emboss about a base material.

In the pressure-sensitive adhesive tape of the present invention 2, the pressure-sensitive adhesive layer contains microbeads. By containing microbeads, if the cross-linking component contained in the pressure-sensitive adhesive layer is cross-linked prior to generating gas at the time of peeling, the entire pressure-sensitive adhesive layer is cured and shrunk, Unevenness corresponding to the size appears on the surface of the pressure-sensitive adhesive layer.

The diameter of the microbead is 3 μm or more. If the thickness is less than 3 μm, the surface of the pressure-sensitive adhesive layer is not sufficiently uneven so as to be a starting point for gas generation, and self-peeling cannot be realized. Preferably it is 8 micrometers or more, More preferably, it is 10 micrometers or more.
Further, the blending amount of the microbeads is not particularly limited, but a preferable lower limit is 1 part by weight and a preferable upper limit is 30 parts by weight with respect to 100 parts by weight of the pressure-sensitive adhesive constituting the pressure-sensitive adhesive layer.

The method for producing the pressure-sensitive adhesive tape of the present invention 2 is not particularly limited. For example, a pressure-sensitive adhesive containing the gas generating agent and microbeads is used on one side of the base material using a doctor knife or a spin coater. And the method of coating.

The present invention 3 realizes self-peeling by forming irregularities on the surface of the pressure-sensitive adhesive layer at the time of peeling by the method of 3) described above, and gas generation that generates gas by stimulation on at least one side of the substrate It is the adhesive tape in which the adhesive layer containing an agent is formed, Comprising: The adhesive layer is an adhesive tape by which the embossing whose height of a convex part is 3 micrometers or more is given to the surface.
As the gas generating agent and the pressure-sensitive adhesive constituting the pressure-sensitive adhesive layer in the pressure-sensitive adhesive tape of the present invention 3, the same ones as those of the pressure-sensitive adhesive tape of the present invention 1 can be used. Moreover, the thing similar to the adhesive tape of this invention 1 can be used except that it is not necessary to emboss about a base material.

In the adhesive tape of this invention 3, the surface of the adhesive layer is embossed. Even if the unevenness formed by embossing is crushed by pressing during bonding, it will appear on the surface of the pressure-sensitive adhesive layer again at the time of peeling if it is for a short period after bonding.

The height of the convex part of the concavo-convex pattern imparted to the surface of the pressure-sensitive adhesive layer by the embossing is 3 μm or more. When the thickness is less than 3 μm, there is no unevenness on the surface of the pressure-sensitive adhesive layer that is high enough to cause gas generation at the time of peeling, and self-peeling cannot be realized. Preferably it is 8 micrometers or more, More preferably, it is 10 micrometers or more.

The method for producing the pressure-sensitive adhesive tape of the present invention 3 is not particularly limited. For example, after the pressure-sensitive adhesive containing the gas generating agent or the like is applied on the base material using a doctor knife or a spin coater. A method of transferring an uneven pattern to an adhesive layer by pressing an embossed sheet, an embossed plate, an embossing roll, etc. on the adhesive layer; applying an adhesive on the embossed surface subjected to a release treatment, and then applying an adhesive layer The method of laminating | stacking the surface in which the embossing of an adhesive layer is not formed on a base material after forming is mentioned.

In the pressure-sensitive adhesive sheet of the present invention, irregularities can be formed on the surface of the pressure-sensitive adhesive layer that adheres to the adherend during peeling. Thereafter, when a stimulus for generating gas from the gas generating agent is given, the gas is uniformly generated starting from the concave and convex portions appearing on the surface of the pressure-sensitive adhesive layer, and peeling of the adhesive surface starts. Thereby, the uniform peeling progresses and the self-peeling can be surely performed without generating non-uniform gas.

ADVANTAGE OF THE INVENTION According to this invention, even if it is a case where it is left for a fixed period after adhesion | attachment, the adhesive tape which can be made to peel from an adherend by giving a stimulus can be provided.

Hereinafter, the present invention will be described in more detail with reference to examples. However, the present invention is not limited only to these examples.

Example 1
(Preparation of adhesive)
The following compounds were dissolved in ethyl acetate and polymerized by irradiating with ultraviolet rays to obtain an acrylic copolymer having a weight average molecular weight of 700,000.
The resin solid content of 100 parts by weight of the ethyl acetate solution containing the acrylic copolymer thus obtained is reacted by adding 3.5 parts by weight of 2-isocyanatoethyl methacrylate, and further the resin of the ethyl acetate solution after the reaction. Mixing 100 parts by weight of solid content with 40 parts by weight of pentaerythritol triacrylate, 5 parts by weight of photopolymerization initiator (Irgacure 651) and 0.5 parts by weight of polyisocyanate to prepare an ethyl acetate solution of adhesive (1) did.
Butyl acrylate 79 parts by weight Ethyl acrylate 15 parts by weight Acrylic acid 1 part by weight 2-hydroxyethyl acrylate 5 parts by weight Photopolymerization initiator 0.2 part by weight (Irgacure 651, 50% ethyl acetate solution)
Lauryl mercaptan 0.01 parts by weight

In addition, 30 parts by weight of 2,2′-azobis- (N-butyl-2-methylpropionamide) and 2,4-, with respect to 100 parts by weight of the resin solid content of the ethyl acetate solution of the pressure-sensitive adhesive (1) A pressure-sensitive adhesive (2) containing a gas generating agent was prepared by mixing 3.6 parts by weight of diethylthioxanthone.

(Production of adhesive tape)
A transparent polyethylene terephthalate (PET) film having a thickness of 50 μm, which has been subjected to corona treatment on one side with an ethyl acetate solution of the pressure-sensitive adhesive (2) and embossed so that the height of the convex portions is 10 μm and the interval between the convex portions is 600 μm. (Embret EM38, manufactured by Unitika Ltd.) On the embossed surface of the embossed EM38, apply with a doctor knife so that the thickness of the dry film from the top of the convex portion is about 50 μm, and heat at 110 ° C. for 5 minutes. Dried. The pressure-sensitive adhesive layer after drying showed adhesiveness in a dry state. Next, a PET film having been subjected to a release treatment was attached to the surface of the pressure-sensitive adhesive (2) layer. Thereafter, static curing was performed at 40 ° C. for 3 days to obtain an adhesive tape.

( Reference Example 2 )
A pressure-sensitive adhesive (3) is obtained by blending 10 parts by weight of microbeads 30 μm in diameter (made by Mitsui Chemicals, Mipperon XM220) with 100 parts by weight of the pressure-sensitive adhesive (2). It was.
The ethyl acetate solution of the adhesive (3) was prepared so that the dry film thickness was about 50 μm on the corona-treated surface of a transparent polyethylene terephthalate (PET) film having a thickness of 50 μm that was corona-treated on one side. It was coated with a doctor knife and heated at 110 ° C. for 5 minutes to dry the coating solution. The pressure-sensitive adhesive layer after drying showed adhesiveness in a dry state. Next, a PET film having been subjected to a release treatment was attached to the surface of the pressure-sensitive adhesive (3) layer. Thereafter, static curing was performed at 40 ° C. for 3 days to obtain an adhesive tape.

( Reference Example 3 )
A 50 μm thick transparent polyethylene terephthalate (PET) film with a corona treatment on one side of the ethyl acetate solution of the pressure-sensitive adhesive (2) so that the dry film thickness is about 50 μm. It was coated with a doctor knife and heated at 110 ° C. for 5 minutes to dry the coating solution. The pressure-sensitive adhesive layer after drying showed adhesiveness in a dry state. Subsequently, the embossed PET (protrusion part interval 30 micrometers) which performed the mold release process was pressed on the surface of an adhesive (2) layer, and the uneven | corrugated pattern was formed in the surface of an adhesive (2) layer. Thereafter, static curing was performed at 40 ° C. for 3 days to obtain an adhesive tape.

(Comparative Example 1)
A 50 μm thick transparent polyethylene terephthalate (PET) film with a corona treatment on one side of the ethyl acetate solution of the pressure-sensitive adhesive (2) so that the dry film thickness is about 50 μm. It was coated with a doctor knife and heated at 110 ° C. for 5 minutes to dry the coating solution. The pressure-sensitive adhesive layer after drying showed adhesiveness in a dry state. Next, a PET film having been subjected to a release treatment was attached to the surface of the pressure-sensitive adhesive (2) layer. Thereafter, static curing was performed at 40 ° C. for 3 days to obtain an adhesive tape.

(Evaluation)
The PET film that protects the pressure-sensitive adhesive (2) layer or the pressure-sensitive adhesive (3) layer is peeled off from the pressure-sensitive adhesive tapes obtained in Example 1, Reference Examples 2, 3 and Comparative Example 1, and is applied to a glass plate using a vacuum press. An adhesive body was prepared by pasting.
After this adhesive is placed with the adhesive tape side down, the illuminance is adjusted using an ultra high pressure mercury lamp from the glass plate side so that the irradiation intensity of the ultraviolet light with a wavelength of 365 nm is 40 mW / cm ^2. And irradiated. The state of gas generation between the adhesive tape and the glass plate was visually observed from the glass side to evaluate what percentage of the entire adhesive surface was peeled off.
The test was performed immediately after the production of the adhesive, left at 60 ° C. for 1 hour, and left at room temperature for 1 month.
In addition, what was peeled 100% visually had the glass completely floated on the adhesive tape and self-peeled.
The results are shown in Table 1.

ADVANTAGE OF THE INVENTION According to this invention, even if it is a case where it is left for a fixed period after adhesion | attachment, the adhesive tape which can be made to peel from an adherend by giving a stimulus can be provided.

Claims (1)

A pressure-sensitive adhesive tape in which a pressure-sensitive adhesive layer containing a gas generating agent that generates gas by stimulation with light, heat or ultrasonic waves is formed on at least one surface of a base material,
The base material is embossed with a height of a convex portion of 3 μm or more on the surface on the pressure-sensitive adhesive layer side,
The pressure-sensitive adhesive layer contains a crosslinking component that is cross-linked by stimulation with light or heat , and the gas generating agent is dissolved in the pressure-sensitive adhesive layer ,
The gas generating agent that generates gas by stimulation with light, heat, or ultrasonic waves is an azo compound or an azide compound,
The pressure-sensitive adhesive tape, wherein the crosslinking component that is crosslinked by stimulation with light or heat comprises a radical polymerizable polyfunctional oligomer or monomer, and a photopolymerization initiator or a thermal polymerization initiator .