JPH1161049A - Photo-peeling type adhesive composition and photo peeling type adhesive tape - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a photo-peeling type adhesive compsn. and a photo-peeling type adhesive tape having enough initial adhesive force, but easily peelable lowering the adhesive force by short time photoradiation, and having little limitation of the kind of objects to be adhered. SOLUTION: This photo-peeling type adhesive compsn. comprises a thermoplastic polymer having not lower than 30 deg.C glass transition temperature (Tg), a photo-cation polymerisable compd., and a photo-cation polymn. initiator, and 10-90 pts.wt. of the thermoplastic polymer is contained in 100 pts.wt. of the total of the thermoplastic polymer and the photo-cation polymerisable compd. This photo-peeling type adhesive tape is formed by laminating the photo- peeling type adhesive compsn. on one or both sides of a support film.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a photo-peelable pressure-sensitive adhesive composition and a photo-peelable pressure-sensitive adhesive tape which can be suitably used for, for example, a protective tape.
The present invention relates to a photo-peelable pressure-sensitive adhesive composition and a photo-peelable pressure-sensitive adhesive tape which have sufficient tackiness under normal conditions and can be easily peeled off by lowering the adhesive strength by light irradiation.

[0002]

2. Description of the Related Art Conventionally, a protection tape for protecting a product from damage or contamination has been known. The protect tape has a structure in which an adhesive layer is formed on one surface of a film having appropriate mechanical strength. The protect tape can be easily attached to the product surface by utilizing the adhesiveness of the adhesive. By attaching this protection tape, the adherend, that is, the product can be protected from external damage and contamination. The protective tape must be easily peelable from the product surface without causing adhesive residue to eventually expose the product surface.

However, in the case of a pressure-sensitive adhesive, a so-called adhesion enhancement phenomenon is generally observed in which the adhesive force increases with time after joining. Therefore, in order to easily peel off after a relatively long time has passed since the tape was adhered to the adherend like a protective tape, it is necessary to suppress the adhesion enhancement phenomenon or to reduce the adhesive force when peeling. Various proposals have been made to enhance the releasability after such long-term application.

For example, Japanese Patent Application Laid-Open No. 49-3434 discloses a method of suppressing the adhesion enhancement phenomenon by blending a phosphate ester with an ethylene-vinyl acetate copolymer-based pressure-sensitive adhesive. Also, Japanese Patent Application Laid-Open No. 51-10733
No. 2 discloses a method for suppressing the adhesion enhancement phenomenon by blending an amine surfactant with a pressure-sensitive adhesive. That is, in the methods described in these prior arts, the phosphate ester or the amine-based surfactant bleeds over time to the interface between the pressure-sensitive adhesive and the adherend, thereby reducing the adhesive force at the interface. .

[0005] However, although phosphoric acid esters and amine-based surfactants suppress the adhesion enhancement phenomenon as described above, if these substances are blended with the pressure-sensitive adhesive, sufficient adhesive strength cannot be obtained, or bleeding cannot occur. There is a possibility that the adherend surface may be contaminated by an object, and the application tends to be restricted.

Japanese Patent Application Laid-Open No. Hei 4-20581 discloses that a photo-radical polymerizable polyfunctional polymer is used, which exhibits a sufficient adhesive strength at the time of attaching an adherend, and that the polyfunctional polymer is irradiated with light at the time of peeling. A method has been disclosed in which the adhesive force is reduced by increasing the crosslink density of the pressure-sensitive adhesive by polymerization to thereby increase the releasability.

[0007] Japanese Patent Application Laid-Open No. 7-286142 discloses that an adhesive having an epoxy group is dispersed in a pressure-sensitive adhesive having a carboxyl group, and heat is applied at the time of peeling. A method for reducing the adhesive force by reacting with particles composed of

[0008]

Problems to be Solved by the Invention
In the method for reducing the adhesive force by photo-radical polymerization as disclosed in Japanese Patent Laid-Open Publication No. H10-207, curing is inhibited by oxygen, and the curing hardly proceeds in a case where a large amount of air bubbles are involved or a surface of the pressure-sensitive adhesive in contact with air. Therefore, in such a case, peeling is difficult, and even if peeled, adhesive residue tends to occur.

In addition, in the photoradical polymerization, since the polymerization reaction proceeds only during irradiation with light, it was necessary to continuously apply strong light energy in order to sufficiently reduce the peeling force. Therefore, workability is not sufficient, and much light energy is required.

On the other hand, in the method disclosed in Japanese Patent Application Laid-Open No. 7-286142, a large-scale apparatus is required for heating in order to reduce the adhesive force by heat, and it is necessary to cool down after processing. . Therefore, the load on the apparatus is large. Furthermore, it cannot be used for heat-sensitive materials such as plastics, and there are many restrictions on the types of adherends.

[0011] It is an object of the present invention to provide a photo-peelable pressure-sensitive adhesive composition and a photo-peelable pressure-sensitive adhesive composition in which the adhesion is reduced by short-time light irradiation, and the light is easily peeled. An object of the present invention is to provide a peelable adhesive tape.

[0012]

According to the first aspect of the present invention, there is provided a thermoplastic polymer having a glass transition point Tg of 30 ° C. or higher, a cationic photopolymerizable compound having a softening point of 80 ° C. or lower, and a cationic photopolymerization initiator. A photo-peelable pressure-sensitive adhesive composition comprising a thermoplastic polymer and a photocationic polymerizable compound in a ratio of 10 to 90 parts by weight based on 100 parts by weight in total.

The invention described in claim 2 is the first invention.
The photo-peelable pressure-sensitive adhesive composition according to claim 1, wherein the photo-peelable pressure-sensitive adhesive composition layer is formed on one or both sides of a support film. Hereinafter, details of the present invention will be described.

(Thermoplastic Polymer) In the photo-peelable pressure-sensitive adhesive composition and pressure-sensitive adhesive tape according to the present invention, the glass transition point Tg
Is 30 ° C. or higher. The glass transition point Tg can be generally determined by measurement of dynamic viscoelasticity or measurement by a differential calorimeter, etc., but in the present specification, refers to a value measured by a differential calorimeter. I do. When the glass transition point Tg of the thermoplastic polymer is less than 30 ° C., even if the photocationically polymerizable compound is polymerized by irradiation with light, the adhesiveness of the thermoplastic polymer is too high, so that the peelability after application cannot be increased. .

The thermoplastic polymer is not particularly limited as long as it has a glass transition point Tg of 30 ° C. or higher, but preferably has low tackiness at room temperature. Examples of the thermoplastic polymer include polyester, polystyrene, poly (meth) acrylate, polyurethane, and polyvinyl acetate. The thermoplastic polymer may be a homopolymer or a copolymer.

In order to adjust the glass transition point Tg, a thermoplastic polymer obtained by copolymerizing a Tg adjusting component may be used.
Examples thereof include butadiene, alkyl (meth) acrylate, aromatic (meth) acrylate, and hydroxyalkyl (meth) acrylate.

In this specification, (meth) acrylate is used as a general term for acrylate and methacrylate. In the present invention, the photo-peelable pressure-sensitive adhesive may be cross-linked, and therefore, the thermoplastic polymer may have a functional group capable of reacting with the cross-linking agent. Such functional groups include, for example, OH group, C
Examples include an OOH group, an epoxy group, and a double bond. However, since a basic functional group such as an amino group may inhibit the cationic polymerization reaction, the smaller the number of the basic functional groups, the better.

(Cationic Photopolymerizable Compound) The cationic photopolymerizable compound used in the present invention must have a softening point of 80 ° C. or lower as measured by the ring and ball method. The softening point of the cationic photopolymerizable compound before curing is 8
When the temperature exceeds 0 ° C., it becomes difficult to pressure-bond the photo-peelable pressure-sensitive adhesive composition according to the present invention at room temperature.

In the present invention, the cationic photopolymerizable compound is
Photocationically polymerizes and gels, thereby significantly changing the tack. That is, in order to increase the initial tackiness and sufficiently adhere the pressure-sensitive adhesive to the adherend, the softening point of the photocationically polymerizable compound before curing is preferably low, and in the range where the volatility is low, the low molecular weight is low. The more preferred. Therefore, if the number average molecular weight of the photocationically polymerizable compound is too large,
Since the adhesion to the adherend is reduced, the number average molecular weight is preferably 10,000 or less, more preferably 1,0.
A photocationically polymerizable compound of not more than 00 is used.

As the photocationically polymerizable compound, an appropriate compound having a photocationically polymerizable functional group in the molecule is used. For example, a compound having a hydroxyl group, a vinyl ether group, an episulfide group, an ethyleneimine group and / or an epoxy group is used. Various monomers and oligomers can be exemplified. The epoxy group-containing monomers and oligomers are not particularly limited, and appropriate epoxy group-containing monomers and oligomers such as bisphenol A type, bisphenol F type, phenol novolak type, cresol novolak type, glycidyl ether type, and glycidylamine type, and these A hydrogenated product or a modified product can be used. In addition, the alicyclic epoxy resin has a large cationic polymerization reaction rate,
It is preferably used because the reaction time becomes short.

Among them, epoxy group-containing oligomers are widely available as main raw materials for epoxy adhesives, so that they are easily available, and have various structures and characteristics. An epoxy group-containing oligomer is preferably used because it can be easily selected.

When an epoxy group-containing compound is used as the cationic photopolymerizable compound, the epoxy equivalent is 5,000 g.
It is preferably at most -regin / mol. If the epoxy equivalent exceeds 5,000 g-regin / mol, the crosslink density becomes low, and the adhesive strength may not be easily reduced even when irradiated with light.

(Photocationic Polymerization Initiator) In the photo-peelable pressure-sensitive adhesive composition according to the present invention, a photocationic polymerization initiator is blended in order to polymerize the photocationically polymerizable compound. In this case, as the cationic photopolymerization initiator, an appropriate one that is activated by irradiation with light and can induce the polymerization of the cationic photopolymerizable compound can be used. That is, the cationic photopolymerization initiator may be any of an ionic photoacid generating type and a nonionic photoacid generating type.

Examples of the ionic photoacid generating type cationic photopolymerization initiator include onium salt compounds such as aromatic diazonium salts, aromatic halonium salts, and aromatic sulfonium salts; iron-allene complexes, titanocene complexes, and arylsilanols. Examples thereof include organometallic complexes such as an aluminum complex. More specifically, for example, Optomer SP-150 (manufactured by Asahi Denka Kogyo), Optmer SP
Commercially available compounds such as -170 (manufactured by Asahi Denka Kogyo), UVE-1014 (manufactured by General Electronics), and CD-1012 (manufactured by Sartomer) can be used.

As the nonionic photoacid-generating type photocationic polymerizable compound, nitrobenzyl ester, sulfonic acid derivative, phosphoric acid ester, phenolsulfonic acid ester, diazonaphthoquinone, N-hydroxyimidosulfonate and the like can be used. Can be.

The above cationic photopolymerization initiators may be used alone or in combination of two or more. Further, using a plurality of cationic photopolymerization initiators having different effective active wavelengths,
Step curing may be performed.

Further, in addition to the cationic photopolymerization initiator, another photopolymerization initiator, for example, a photoradical polymerization initiator or a photoanionic polymerization initiator may be used in combination. In this case, the wavelength of light for activating the photo-radical polymerization initiator or the photo-anionic polymerization initiator does not necessarily need to be equal to the wavelength for activating the photo-cationic polymerization initiator.

The light includes microwaves, infrared rays,
Visible light, ultraviolet light, X-rays, γ-rays, and the like can be used, but generally, ultraviolet light that is easy and easy to handle and can obtain relatively high energy is preferably used. More preferably, ultraviolet light having a wavelength of 200 to 400 nm is used.

The ultraviolet rays can be irradiated using an appropriate light source such as a high-pressure mercury lamp, a microwave excitation type lamp, and a chemical lamp.

(Blending Ratio) The thermoplastic polymer and the cationic photopolymerizable compound are blended so as to contain 10 to 90 parts by weight of the thermoplastic polymer based on 100 parts by weight of the total. If the blending ratio of the thermoplastic polymer is larger than this range, sufficient initial tackiness cannot be obtained, and if the blending ratio of the thermoplastic polymer is less than the above range, the cohesiveness will be low, and the shift of the pressure-sensitive adhesive and There is a risk of exudation.

The cationic photopolymerization initiator is used in an amount sufficient to induce photocationic polymerization by irradiation of the photocationically polymerizable compound with light. It is appropriately selected according to the type of the cationic photopolymerizable compound. For example, when an epoxy group-containing photocationically polymerizable compound is used, preferably, the cation is irradiated with light to 0.0 mol per 1 mol of the epoxy group.
The cationic photopolymerization initiator is blended so as to generate 001 mol% or more. When the amount is less than 0.0001 mol%, the cationic photopolymerization does not sufficiently proceed, and the time until the adhesive strength decreases may be too long.

(Crosslinking) In the photo-peelable pressure-sensitive adhesive composition according to the present invention, in order to balance wettability and cohesive force between the adherend and the photo-peelable pressure-sensitive adhesive, the composition is cross-linked before light irradiation. May be blended.

The method of crosslinking is not particularly limited, but it depends on the functional group in the photo-peelable pressure-sensitive adhesive composition and a polyfunctional oligomer (for example, polyisocyanate, polyepoxy, polyol, polyfunctional acrylic oligomer, etc.). Molecular crosslinking and ionic crosslinking by metal oxides or metal chelates are common.

The crosslinking is desirably carried out to a certain extent when the insoluble portion (gel fraction) of the photo-peelable pressure-sensitive adhesive composition is 1 to 70% by weight. If the initial crosslinking degree is higher than this, the wettability to the adherend is reduced, and a sufficient initial adhesive strength may not be obtained. If the initial crosslinking degree is lower than the above range, the cohesive strength is insufficient, and the adhesive may be displaced or thermally peeled off.

(Light-peelable pressure-sensitive adhesive tape) The light-peelable pressure-sensitive adhesive tape according to the present invention is formed by laminating the above-mentioned light-peelable pressure-sensitive adhesive composition on one or both sides of a support film. In this case, as the support film, an appropriate synthetic resin film or the like having appropriate mechanical strength can be used, but a light transmissive film is preferably used. When the light-peelable pressure-sensitive adhesive composition is laminated on one surface of a light-transmissive support film to form a light-peelable pressure-sensitive adhesive tape, after being attached to an adherend, light is irradiated from the back side of the support film. Photocationic polymerization can be triggered.

The light transmittance means that light having an active wavelength of the cationic photopolymerization initiator is transmitted.
Preferably, the transmittance at the active wavelength is 30% or more. When this transmittance falls below 30%,
It may take time to cure the adhesive.

However, when the adherend is made of a transparent material, after applying the photo-peelable adhesive tape,
Light cation polymerization may be caused by irradiating light from the adherend side. Therefore, the support film does not necessarily have to have light transmittance.

Examples of the light-transmitting film that can be used as the support film include polyethylene terephthalate, polyethylene naphthalate, polyethylene, polypropylene, polycarbonate, nylon, polyarylate, polysulfone, polyether sulfone, polyether ether ketone, polyphenylene sulfide, and the like. Polystyrene, polyacryl, polyvinyl acetate, triacetyl cellulose, diacetyl cellulose, cellophane and the like can be exemplified, but they are not particularly limited as long as they have light transmittance.

The thickness of the support film is not particularly limited as long as it has sufficient mechanical strength, but is preferably at least 1 μm, more preferably at least 10 μm. If the thickness of the support film is too thin, the strength is reduced and the support film may be broken during use. Note that the upper limit of the thickness of the support film is appropriately determined depending on the light transmittance and the like.

(Form of Use) The photo-peelable pressure-sensitive adhesive composition according to the first aspect of the present invention can be used as a pressure-sensitive adhesive tape by being coated on a suitable support. Further, when coated on a release support, it can be used as a non-support type double-sided tape.

When the photo-peelable pressure-sensitive adhesive composition is applied to form a pressure-sensitive adhesive layer, the thickness is preferably in the range of 1 to 500 μm, more preferably 10 to 200 μm. If the thickness of the pressure-sensitive adhesive layer is less than 1 μm, the adhesiveness may be insufficient, and a sufficient adhesive strength may not be obtained.
If it is thicker than m, it may take a long time to cure.

In applying the above-mentioned light-peelable pressure-sensitive adhesive composition, an appropriate coating method can be used. For example, various coating and forming methods such as a roll coating method, a gravure coating method, and an extrusion molding method can be used. Can be used.

When the photo-peelable pressure-sensitive adhesive composition is solid,
Or when the viscosity is too high to be easily applied even in a liquid state, by diluting the photo-peelable pressure-sensitive adhesive composition with an appropriate solvent, or by melting the photo-peelable pressure-sensitive adhesive by heating, Its viscosity may be reduced.

As the solvent used for dilution, an appropriate organic solvent capable of dissolving the photo-peelable pressure-sensitive adhesive composition can be used, and an organic solvent having a boiling point of about 40 to 200 ° C. is preferably used. For example, acetone, methyl ethyl ketone, methyl isobutyl ketone, ethyl formate, butyl formate, methyl acetate, ethyl acetate, butyl acetate, toluene,
Common solvents such as p-xylene, n-hexane, cyclohexane, chloroform, carbon tetrachloride and the like can be mentioned. In addition, general solvents are described in detail in "Solvent Handbook" published by Kodansha. When using these organic solvents, it is desirable to select one having high compatibility with the photo-peelable pressure-sensitive adhesive composition.

In the light-peelable pressure-sensitive adhesive tape according to the second aspect of the present invention, the light-peelable pressure-sensitive adhesive composition is applied to one or both surfaces of a support film. In this case, the thickness of the pressure-sensitive adhesive layer is preferably as described above. Also,
The method of applying the light-peelable pressure-sensitive adhesive can be performed by an appropriate method as in the case of applying the light-peelable pressure-sensitive adhesive composition according to the first aspect of the present invention.

The adhesive surface of the photo-peelable pressure-sensitive adhesive tape is preferably covered and protected by a releasable support having a releasable surface. Furthermore, when the light-peelable pressure-sensitive adhesive tape is in the form of a double-sided pressure-sensitive adhesive tape formed by forming a light-peelable pressure-sensitive adhesive layer on both sides of a support film, both sides of the light-peelable pressure-sensitive adhesive tape are separated by a surface-peelable support. It is desirable to be covered and protected. Therefore, in the case of a double-sided pressure-sensitive adhesive tape, it is desirable that both pressure-sensitive adhesive surfaces be laminated with a surface-peelable support and wound into a roll.

(Other usable components) In the pressure-sensitive adhesive composition of the present invention and the pressure-sensitive adhesive layer of the light-peelable pressure-sensitive adhesive tape, appropriate additives are blended within a range not to impair the object of the present invention. can do. Such additives include tackifiers for improving adhesion, plasticizers for imparting flexibility, light absorbers for adjusting and controlling light intensity, and peeling for adjusting peeling force. Property imparting agent,
Water absorbing agents, water retaining agents, fillers, antiblocking agents and the like can be mentioned.

(Use) The photo-peelable pressure-sensitive adhesive composition according to the first aspect of the present invention can be used, for example, as a pressure-sensitive adhesive for forming a protective tape, but in addition, sufficient adhesiveness is required. And can be generally used for applications that require removal of the pressure-sensitive adhesive without causing adhesive residue after a certain period of time. In addition, the photo-peelable pressure-sensitive adhesive composition according to the first aspect of the present invention does not necessarily need to be applied to a support film to be in the form of a pressure-sensitive adhesive tape. That is, when joining two adherends,
The photo-peelable pressure-sensitive adhesive composition according to the first aspect of the present invention may be used in the same manner as a normal pressure-sensitive adhesive or adhesive.

On the other hand, the photo-peelable pressure-sensitive adhesive tape according to the second aspect of the present invention can also be suitably used in an environment where adhesion is likely to increase, such as bonding at a high temperature for a long time. Also, the peelability can be reliably increased by light irradiation. However, if light is irradiated in the affixed state, a polymerization reaction occurs, and the adhesive strength is reduced. Therefore, it is desirable to use the light-shielded environment except during peeling.

The photo-peelable pressure-sensitive adhesive tape according to the second aspect of the present invention can also be suitably used as a conventional protect tape. In addition, as described above, the pressure-sensitive adhesive tape is suitable for an environment where adhesion is likely to increase. Can be used.

(Function) In the photo-peelable pressure-sensitive adhesive composition according to the first aspect of the present invention, the thermoplastic polymer exhibits sufficient tackiness to an adherend in an initial state by irradiation with light. The photocationically polymerizable compound is polymerized to reduce the adhesive force. Therefore, the photo-peelable pressure-sensitive adhesive can be easily peeled from the adherend that is weak to heat by light irradiation.

Further, since photocationic polymerization is utilized, polymerization is not inhibited by oxygen. Therefore, the polymerization reaction proceeds uniformly by light irradiation, and the adhesive strength is surely reduced. In addition, in the cationic photopolymerization, since the polymerization reaction proceeds even after the irradiation of light is stopped, the energy cost can be reduced.

In the light-peelable pressure-sensitive adhesive tape according to the second aspect of the present invention, the pressure-sensitive adhesive layer composed of the light-peelable pressure-sensitive adhesive composition is formed on at least one surface of the support film. In the initial state, the adhesive has a sufficient adhesive strength, and the adhesive strength is surely reduced by irradiating light. Further, since the cationic photopolymerization proceeds even after the light irradiation is stopped, the energy cost can be reduced.

[0054]

The present invention will be clarified by the following non-limiting examples.

(Example 1) Polyester: manufactured by Toyobo Co., Ltd., trade name: Byron 20
0, Tg = 67 ° C Bisphenol A type epoxy oligomer: manufactured by Yuka Shell Epoxy Co., Ltd., trade name: Epicoat 828, epoxy equivalent 190, liquid at room temperature Photocationic polymerization initiator: manufactured by Asahi Denka Co., trade name: SP1
70 Ethyl acetate Each of the above components is weight ratio of ::: = 50:50:
The components were mixed at a ratio of 3: 100, and stirred and mixed so as to be sufficiently uniform. The epoxy equivalent in the obtained composition was 391 g-regin / mol, and the cation mol equivalent was 0.45 mol%.

(Example 2) Polymethyl methacrylate (trade name: LP, manufactured by Asahi Kasei Corporation)
-1, Tg = 105 ° C. Alicyclic epoxy oligomer: Asahi Denka Co., Ltd., trade name: K
RM2110, epoxy equivalent 140, liquid at room temperature Photocationic polymerization initiator: Optomer SP170 Solvent: methyl ethyl ketone The above is expressed in a weight ratio of ::: = 70: 3.
The components were blended at a ratio of 0: 3: 100 and stirred and mixed so as to be sufficiently uniform. The epoxy equivalent in the obtained composition is 206
g-regin / mol, cation mol equivalent is 0.2
It was 4 mol%.

Example 3 Methyl methacrylate / butadiene / 2-hydroxyethyl acrylate copolymer: Polymerization ratio: methyl methacrylate: butadiene: 2-hydroxyethyl acrylate = 80: 19: 1, Tg = 55 ° C. phenol Novolak type epoxy oligomer: manufactured by Asahi Denka Co., Ltd., trade name: KRM2610, epoxy equivalent 190,
Softening point = 70 ° C. Photocationic polymerization initiator: manufactured by Asahi Denka Co., Ltd., trade name: Optomer SP170 Isocyanate crosslinking agent: manufactured by Nippon Polyurethane Co., Ltd., trade name: Coronate L-55E Solvent: methyl ethyl ketone 70 to 30 by weight ratio : 3: 1.5: 10
0, and stirred and mixed so as to be sufficiently uniform.
The epoxy equivalent of the obtained composition was 652 g-regin.
/ Mol, cation mol equivalent was 0.75 mol%.

Comparative Example 1 Ethyl polyacrylate: Tg = −25 ° C. Trimethylolpropane trimethacrylate Photopolymerization initiator: BASF, trade name: Lucirin TP
O 2 solvent: ethyl acetate The above components were mixed at a polymerization ratio of 60: 40: 1: 50, and were mixed so as to be sufficiently uniform.

Comparative Example 2 Butyl acrylate / 2-hydroxyethyl acrylate copolymer: copolymerization ratio: butyl acrylate: 2-hydroxyethyl acrylate = 99: 1, Tg = -50
C Stearic acid Crosslinking agent: Isocyanate-based crosslinking agent, manufactured by Nippon Polyurethane Co., Ltd., trade name: Coronate L-55E Solvent: Toluene The above is blended at a polymerization ratio of 97: 3: 2: 100 so as to be sufficiently uniform. Stir and mix.

(Manufacture of photo-peelable pressure-sensitive adhesive tape) Each of the pressure-sensitive adhesive compositions prepared in Examples and Comparative Examples was treated with a 50 μm-thick polyethylene terephthalate (PE) having a surface subjected to release treatment.
T) The film was applied on a film using a roll coater so that the final thickness became 20 μm, and dried at 100 ° C. for 3 minutes to obtain an adhesive sheet. Further, in order to protect the adhesive surface, a release PET film having a thickness of 38 μm whose surface was subjected to silicone release treatment was laminated.

(Evaluation of Examples and Comparative Examples) With respect to the pressure-sensitive adhesive tapes obtained as described above, (1) initial adhesive strength,
(2) Adhesive force after adhesion enhancement, (3) Peeling force, and (4) Adherend contamination were evaluated.

(1) Initial adhesive strength PET having a length of 120 mm × a width of 50 mm × a thickness of 100 μm
The release PET film on one side of the pressure-sensitive adhesive tape cut to a width of 25 mm was peeled off from the adherend, and pressure-bonded from the back of the pressure-sensitive adhesive tape at a speed of 300 mm / min with a laminator while applying a pressure of 3 kg / cm. After pressing, the remaining release PET film was peeled off, and an adherend made of PET was pressed onto the exposed adhesive surface in the same manner as above, and left at room temperature for 1 hour. Then, the adhesive tape was applied in the T direction at a speed of 300 mm / min. After peeling, the peel resistance was measured.

(2) Adhesion after adhesion enhancement (1) A test piece pressed in the same manner as in the initial adhesion was
After placing in a gear oven at 10 ° C. for 10 days, the test piece was taken out of the oven, left at room temperature for 1 hour, and the peel resistance was measured in the same manner as (1).

(3) Peeling force With respect to Examples 1 to 3 and Comparative Examples 1 and 2, pressure was applied in the same manner as in (2) Evaluation of adhesion after adhesion enhancement, and from one surface of the test piece with increased adhesion, using a high-pressure mercury lamp. Center wavelength 365nm
UV light was applied so as to have a light energy of 0.5 J / cm ² and cured. After one day at room temperature, (1)
Peeling was performed by the same peeling method as described above, and the peeling resistance was measured.

(4) Adherend Contamination (3) A surface inspection lamp (F-100 manufactured by Funakoshi Yakuhin Co., Ltd., trade name: F-100)
Z), and the presence or absence of glue residue and discoloration was visually confirmed. The results are shown in Table 1 below.

[0066]

[Table 1]

In Table 1, the cross-linking ratio * 1 is based on the insoluble matter (gel) obtained by immersing the adhesive of the pressure-sensitive adhesive tape in about 100 times its weight of ethyl acetate and leaving it for 24 hours to elute the sol. Is filtered with a 200 mesh and dried, and the weight fraction of the filtered gel relative to the pressure-sensitive adhesive before immersion is measured. * 2 indicates that tape floating has occurred.

In Comparative Example 1, since the photoradical polymerization reaction was used, unreacted monomers remained, possibly because the tape edge was inhibited from curing by atmospheric oxygen, and contamination of the adherend surface was observed. . In addition, the monomer remained in the central portion, probably due to insufficient curing energy or insufficient curing.

In Comparative Example 2, the entire surface of the adherend was contaminated with the bleed material. In addition, excessive bleeding caused by heating greatly reduced the adhesive force, and partially caused lifting.

As is clear from Table 1, Example 1
In Nos. 1 to 3, the adhesion was increased when the adhesion was increased in a gear oven at 50 ° C. for 10 days as compared with the initial adhesion, but the peeling force was significantly reduced by light irradiation, and therefore, the adhesion from the adherend was easy. It can be seen that peeling is possible. Also, in this case, no adhesive residue was found at either the end or the center of the tape. Therefore, it can be seen that both high initial adhesive strength and low peeling force can be achieved without causing contamination of the adherend.

(Examples 4 to 6 and Comparative Examples 4 to 6) The pressure-sensitive adhesives used in Examples 1 to 3 and Comparative Examples 1 and 2 were used, except that the plastic film (thickness 50) shown in Table 2 below was used.
μm), as in Examples 1-3 and Comparative Examples 1 and 2,
Coating was performed so that the final thickness became 20 μm, to prepare an adhesive tape. Further, in order to protect the adhesive surface, a release PET film having a thickness of 38 μm and subjected to a silicone release treatment was laminated.

The properties of Examples 4 to 6 and Comparative Examples 4 to 6 are shown in Table 3 below together with the evaluation results. In Table 3,
Ex1 to Ex3 in the column of pressure-sensitive adhesive are Examples 1 to 3, respectively.
3, and C1 and C2 indicate the adhesives used in Comparative Examples 1 and 2, respectively.

Table 3 also shows the PET film, the black PET film, and the PEN film as the above-mentioned support films and their light transmittances. For each of the pressure-sensitive adhesive tapes of Examples 4 to 6 and Comparative Examples 4 to 6 obtained as described above, (1) initial adhesive strength, (2) adhesive strength after increased adhesion, ( 3) Peeling force and (4)
The adherend contamination was evaluated. The results are shown in Table 3.

[0074]

[Table 2]

[0075]

[Table 3]

* 1 in Table 3 indicates a wavelength of 365 n
It is a value measured in m. * 2 is a value measured in the same manner as the crosslinking rate in Table 1. Further, * 3 indicates that tape floating has occurred.

In Comparative Example 4, since the support film was black PET and was non-light-transmitting, no photocationic polymerization reaction occurred and the peeling force did not decrease. Therefore, adhesive residue was generated on the entire surface during peeling.

In Comparative Example 5, since the photoradical polymerization reaction was used, unreacted monomer remained, probably because the tape edge was inhibited from curing by atmospheric oxygen, and the adherend surface was contaminated.

In Comparative Example 6, the entire surface of the adherend was contaminated with the bleed material. In addition, since the adhesive force was significantly reduced due to excessive bleeding due to heating, partial lifting occurred.

On the other hand, in Examples 4 to 6, various light-transmitting films were used as the support films as in Examples 1 to 3, but they had a sufficient initial adhesive strength.
In addition, the peeling force after curing was reliably reduced, and no adhesive residue was generated during peeling.

[0081]

In the photo-peelable pressure-sensitive adhesive composition according to the first aspect of the present invention, since the thermoplastic polymer and the photo-cationic polymerizable compound are blended in the above-mentioned specific ratio, sufficient initial adhesive strength can be obtained. To sufficiently adhere to an adherend. In addition, the adhesive strength is increased by the increase in adhesion with time, but the photocationically polymerizable compound is polymerized by irradiating light during peeling, and the peeling strength is significantly reduced. Therefore, without leaving glue residue from the adherend,
It can be easily peeled off.

In particular, since the decrease in the peeling force is brought about by the cationic photopolymerization, the curing is hardly inhibited by oxygen, so that even if bubbles are trapped or exposed to the atmosphere, the peeling is surely performed. The power is reduced. in addition,
Since the peeling force is not reduced by heat, there is little restriction on the adherend. Furthermore, since the cationic photopolymerization reaction proceeds even after the irradiation of light is stopped, not much light energy for lowering the peeling force is required, and energy cost can be reduced.

In the photo-peelable pressure-sensitive adhesive tape according to the second aspect of the present invention, the photo-peelable pressure-sensitive adhesive composition is laminated on one side or both sides of a support film. Like the photo-peelable pressure-sensitive adhesive composition, when affixed to an adherend, it has a sufficient initial adhesive strength, and is polymerized and cured by a photo-cationic polymerization initiator upon irradiation with light, so that the peeling strength is ensured. descend. Therefore, it is possible to provide a photo-peelable pressure-sensitive adhesive tape suitable for a protective tape or the like in which a high initial adhesive force and a low peel force are balanced.

Further, similarly to the photo-peelable pressure-sensitive adhesive composition according to the first aspect of the present invention, the photo-peelable pressure-sensitive adhesive tape according to the second aspect of the present invention can also be applied to the adherend by reducing the peeling force. The surface is not easily contaminated, and the photocation polymerization reaction proceeds even after the irradiation of light is stopped, so that the energy cost can be reduced.

Claims (2)

[Claims] 1. A thermoplastic polymer having a glass transition point Tg of 30 ° C. or higher, a cationic photopolymerizable compound having a softening point of 80 ° C. or lower, and a cationic photopolymerization initiator, and the total of the thermoplastic polymer and the cationic photopolymerizable compound A photo-peelable pressure-sensitive adhesive composition, characterized in that the thermoplastic polymer is used in an amount of 10 to 90 parts by weight based on 100 parts by weight. 2. A photo-peelable pressure-sensitive adhesive tape, wherein the photo-peelable pressure-sensitive adhesive composition layer according to claim 1 is formed on one or both surfaces of a support film.