JPH11106722A - Production of pressure-sensitive adhesive tape - Google Patents

Abstract

PROBLEM TO BE SOLVED: To produce a pressure-sensitive adhesive tape having excellent adhesiveness to a high-polarity surface adherend such as a metal at ordinary temperature and resisting to deterioration in adhesiveness upon lowering to low temperature. SOLUTION: A photopolymerizable composition containing an alkyl (meth) acrylate, a polar-group-containing vinyl monomer, a reactive monomer having at least two reactive double bonds in the molecule and a photopolymerization initiator with the proviso that the alkyl (meth)acrylate and the polar-group- containing vinyl monomer are contained in such amounts that the composition comprising these two components has a Fedors' theoretical solubility parameter in the range of 10.0-15.0 cal/cm<3> is foamed and photopolymerized to obtain a cellular pressure-sensitive adhesive film containing 3-10 vol.% cells.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing an acrylic pressure-sensitive adhesive tape, and more particularly, to a method for producing a pressure-sensitive adhesive tape which is not easily reduced in adhesiveness to an adherend having a high surface polarity and in adhesive strength due to temperature change. About the method.

[0002]

2. Description of the Related Art Conventionally, as a pressure-sensitive adhesive for forming an adhesive tape, a heat-polymerizable solvent-type pressure-sensitive adhesive and a photopolymerization-type pressure-sensitive adhesive have been known. The photopolymerizable pressure-sensitive adhesive is obtained by providing a photopolymerizable composition layer on the surface of a film-like base material, and irradiating the composition layer with light to polymerize.

In order to obtain a suitable photopolymerizable pressure-sensitive adhesive for various adherends, it is necessary to change the monomer composition according to the adherend. For example, for use on adherends with high surface polarity such as metals such as iron, if the pressure-sensitive adhesive surface is configured to have the same high surface polarity, high adhesion to these adherends is achieved. It is known that force can be developed.

[0004]

The inventors of the present invention increased the surface polarity of the photopolymerizable pressure-sensitive adhesive in order to obtain a high adhesive strength to metals and the like. It was found that the cohesive strength of the pressure-sensitive adhesive polymer increased as the temperature decreased, but the pressure-sensitive adhesive strength as a pressure-sensitive adhesive was extremely lowered at 0 ° C. or lower.
That is, the effect of improving the adhesion to metals and the like by increasing the polarity and the low-temperature adhesion are in conflict with each other, and it is extremely difficult to satisfy both of them.

On the other hand, Japanese Patent Publication No. 3-40752 discloses that
It is described that by dispersing bubbles having an average bubble diameter of not more than 0.3 mm in a photopolymerizable pressure-sensitive adhesive, the adhesiveness when the temperature is lowered can be enhanced. That is,
At low temperatures, the elastic modulus of the viscoelastic adhesive polymer increases and lowers the low-temperature adhesive strength, but by including bubbles that are unlikely to change in temperature, the decrease in adhesive strength when the temperature decreases is suppressed. Have been.

However, in the case of the photopolymerizable pressure-sensitive adhesive described in Japanese Patent Publication No. 3-40752, the decrease in the adhesive force when the temperature is reduced is suppressed, but the decrease in the cohesive force of the pressure-sensitive adhesive is reduced. Significantly, there has been a problem that the adhesion to an adherend having a high surface polarity at room temperature becomes too low.

[0007] Accordingly, an object of the present invention is to exhibit sufficient adhesiveness to an adherend having a high surface polarity such as a metal surface, and to adhere to a temperature change, particularly when the temperature changes to a low temperature such as 0 ° C or less. An object of the present invention is to provide a method for producing an adhesive tape in which a reduction in force is unlikely to occur.

[0008]

According to the method for producing a pressure-sensitive adhesive tape of the present invention, an alkyl (meth) acrylate, a vinyl monomer having a polar group, and a reactive double bond are contained in a molecule.
Including a reactive monomer and a photopolymerization initiator having at least one
The composition comprising an alkyl (meth) acrylate and a vinyl monomer having a polar group has a theoretical solubility parameter of Fedors of 10.0 to 15.0 (cal / c).
m ³ ) By bubbling a photopolymerizable composition containing an alkyl (meth) acrylate and a vinyl monomer having a polar group so as to be in the range of ^1/2 , photopolymerization is carried out to obtain 3 to 10% by volume. It is characterized in that a foamy pressure-sensitive adhesive film containing bubbles is obtained.

Hereinafter, the present invention will be described in detail. In the present invention, as the acrylic (meth) acrylate,
Although not particularly limited, an alkyl (meth) acrylate having an alkyl group having 1 to 12 carbon atoms, which is generally used for an acrylic pressure-sensitive adhesive, is preferably used, and an alkyl having 4 to 12 carbon atoms is preferable. An alkyl (meth) acrylate having a group is used. Note that (meth) acrylate is used as a general term for acrylate and methacrylate.

Specific examples of the above alkyl (meth) acrylate include n-butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, isooctyl (meth) acrylate, n-octyl (meth) acrylate, and isononyl (meth) acrylate. And lauryl (meth) acrylate. In addition, the said alkyl (meth) acrylate may be used independently and may be used together 2 or more types.

In consideration of the balance between tackiness and cohesive force, the glass transition point (Tg) of a normal homopolymer is 10
The main component is (meth) acrylate below ℃, and methyl (meth) acrylate or ethyl (meth)
A lower alkyl (meth) acrylate such as acrylate may be used in combination.

The vinyl monomer having a polar group is not particularly limited, and an appropriate polar vinyl monomer used for forming an acrylic pressure-sensitive adhesive can be used. Specific examples of the vinyl monomer having a polar group include carboxyl group-containing monomers such as (meth) acrylic acid, maleic acid, fumaric acid, and itaconic acid or anhydrides thereof; (meth) acrylonitrile, N-vinylpyrrolidone, N-vinylcaprolactam, acroylmorpholine, (meth) acrylamide,
Nitrogen-containing monomers such as dimethylaminoethyl (meth) acrylate, diethylaminoethyl (meth) acrylate, and dimethylaminopropylacrylamide; 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 4-hydroxybutyl acrylate, caprolactone Hydroxy group-containing monomers such as modified (meth) acrylate, polyoxyethylene (meth) acrylate, and polyoxypropylene (meth) acrylate can be exemplified.

Regarding the mixing ratio of the acrylic (meth) acrylate and the polar group-containing vinyl monomer, the theoretical solubility parameter of Fedors of the monomer composition composed of both is 10.0 to 15.0 (cal / cm ³ ) ^1/2 . Adjusted to be within range. When the above theoretical solubility parameter is smaller than 10.0 (cal / cm ³ ) ^1/2 , the pressure-sensitive adhesion to a highly polar adherend such as a metal is reduced, and 15.0 (cal / cm ^3). If it exceeds ^1/2 , the pressure-sensitive adhesiveness at room temperature will decrease.

The mixing ratio of the acrylic (meth) acrylate and the polar group-containing vinyl monomer is as follows.
It is necessary to adjust so as to be within the range of the above-mentioned theoretical solubility parameter.
The weight ratio of acrylate to polar group-containing vinyl monomer is 7
By setting the ratio in the range of 5:25 to 95: 5, a monomer composition within the above-mentioned theoretical solubility parameter range can be obtained.

The above theoretical solubility parameter (s
There are various methods and calculation methods for calculating p).
In the present specification, the value is based on a calculation method devised by Fedors (Journal of the Adhesion Society of Japan, vol. 22, n.
o. 10 (1986) (53) (566)). Since this calculation method does not require a value of density, the solubility parameter can be easily calculated.

That is, the theoretical solubility parameter (sp) of Feodors is calculated by the following equation. (ΣΔel / ΣΔvl) ^1/2 where ΣΔel = (ΔH-RT) ΣΔvl / sum of molar volumes

An example of calculation of the above theoretical solubility parameter is as follows. For example, 9.7 (cal) for butyl acrylate
/ Cm ³ ) ^1/2 , 8.6 (cal / cm ³ ) ^{1/2 for} 2-ethylhexyl acrylate, and 14.3 for acrylic acid.
0 (cal / cm ³ ) ^1/2 .

The theoretical solubility parameter of the composition obtained by mixing the acrylic (meth) acrylate and the polar group-containing vinyl monomer is calculated based on the sum of the mole fractions of the two components. Therefore, the theoretical solubility parameter of the above monomer composition is set to 10.0 (cal / cm ³ ).
^{In order} to reduce the content to ^1/2 or more, for example, when an acrylic (meth) acrylate monomer smaller than 10.0 (cal / cm ³ ) ^1/2 such as 2-ethylhexyl acrylate is used as a main component, the main component is used. A polar group-containing vinyl monomer having a high theoretical solubility parameter, such as acrylic acid, may be mixed with the above monomer.

The reactive monomer having two or more double bonds in the molecule acts to crosslink a polymer obtained by polymerizing the photopolymerizable composition, and the reactive monomer is not particularly limited. Hexanediol di (meth) acrylate, (poly) ethylene glycol di (meth) acrylate, (poly) propylene glycol di (meth) acrylate, neopentyl glycol di (meth) acrylate, pentaerythritol di ( (Meth) acrylate, pentaerythritol tri (meth) acrylate, trimethylolpropane trimethacrylate, allyl (meth) acrylate, vinyl (meth) acrylate, divinylbenzene, other epoxy acrylate, polyester acrylate or urethane acrylate Etc. can be suitably used.

The proportion of the reactive monomer having two or more double bonds in the molecule is preferably 0.01 to 1 with respect to 100 parts by weight of the total of the acrylic (meth) acrylate and the polar group-containing vinyl monomer. 0.0 parts by weight, more preferably 0.02 to 0.8 parts by weight. When the proportion of the reactive monomer is less than 0.01 part by weight,
If the degree of crosslinking is insufficient, the necessary cohesive strength may not be obtained. If the amount exceeds 1.0 part by weight, the crosslink density becomes high, the cohesive strength becomes too high, and the pressure-sensitive adhesiveness may be impaired. .

As the photopolymerization initiator, an appropriate photopolymerization initiator which can be used for photopolymerizing the above monomer composition can be used. For example, 4- (2-hydroxyethoxy) phenyl (2-hydroxy- 2-propyl) ketone [for example, Ciba-Geigy Co., Ltd., trade name: Darocur 29]
59], α-hydroxy-α, α′-dimethylacetophenone [for example, Ciba-Geigy, trade name: Darocur 1173], methoxyacetophenone, 2,2-dimethoxy-2-phenylacetone [for example, Ciba-Geigy, trade name: Irga Cure 651], acetophenone-based photopolymerization initiators such as 2-hydroxy-2-cyclohexyl acetophenone [manufactured by Ciba Geigy, trade name: Irgacure 184]; ketal-based photopolymerization initiators such as benzyl dimethyl ketal; and other halogenated ketones ,
Examples include photopolymerization initiators such as acylphosphinoxide and acylphosphanate.

If the mixing ratio of the photopolymerization initiator is too small, the polymerization conversion rate will decrease, and the residual monomer odor will increase. If the content ratio of the photopolymerization initiator is too high, the amount of generated radicals will be too large, and the molecular weight will increase. And the required initial cohesion may not be obtained. Therefore, the mixing ratio of the photopolymerization initiator is preferably 0.01 to 5 parts by weight, more preferably 0.05 to 3 parts by weight, based on 100 parts by weight of the total of the acrylic (meth) acrylate and the polar group-containing vinyl monomer. Department.

(Photopolymerization) In the method for producing a pressure-sensitive adhesive tape according to the present invention, the monomer composition containing the above essential components is foamed and photopolymerized. In this case, visible light, ultraviolet light, or an electromagnetic wave such as an electron beam can be used as light, and light is a generic term for light in this specification.

The lamps used for light irradiation are not particularly limited, but those having an emission distribution at a light wavelength of 400 nm or less are preferably used. For example, low-pressure mercury lamps, medium-pressure mercury lamps, high-pressure mercury lamps, Examples include a high-pressure mercury lamp, a chemical lamp, a black light lamp, a microwave excitation mercury lamp, and a metal halide lamp. Preferably, a chemical lamp is used. The chemical lamp efficiently emits light in the active wavelength region of the photopolymerization initiator, and hardly causes light absorption in components other than the photopolymerization initiator. Enables production of adhesive tape products with a film thickness.

The light irradiation intensity is a factor that affects the degree of polymerization of the obtained polymer, and should be appropriately controlled according to the intended performance of the pressure-sensitive adhesive tape. However, when a conventional cleavage type photopolymerization initiator having an acetophenone group is used, a wavelength region effective for photodecomposition of the photopolymerization initiator (which varies depending on the photopolymerization initiator, usually 365 to 420 nm)
Light intensity is 0.1 to 100 mW / c
m ² is preferable.

The photopolymerization in the present invention is inhibited by oxygen in the air and oxygen dissolved in the photopolymerizable composition. Therefore, light irradiation is desirably performed by a process method capable of eliminating inhibition of oxygen. As such a technique, the photopolymerizable composition is coated with a film such as polyethylene terephthalate (PET) or a fluoroethylene resin whose surface has been release-treated, and light is applied to the photopolymerizable composition via the film. Irradiation method and the like can be mentioned. Alternatively, the reaction may be performed in an inert zone which has a light-transmitting window and has an atmosphere in which oxygen is replaced by an inert gas such as nitrogen gas or carbon dioxide gas. In the method in which the reaction is performed in the inert zone, the oxygen concentration in the irradiation atmosphere is set to 5000 ppm in order to complete the reaction sufficiently until the polymerization conversion of the photopolymerizable composition becomes 99.7%.
It is desirable to set the following, more preferably 300p
pm or less.

During the photopolymerization, when the reaction proceeds rapidly, the release-treated film coated with the photopolymerizable composition or the release-treated film for the cover expands and contracts due to the heat of polymerization, and the resulting adhesive sheet has vertical stripes. May occur. In this case, the radiation heat from the lamp may be suppressed by a light cut filter, or the sheet may be cooled by passing the rear surface of the sheet opposite to the side irradiated with light into contact with the cooling plate.

In the present invention, photopolymerization is carried out by bubbling the photopolymerizable composition so that the pressure-sensitive adhesive film obtained by photopolymerization contains bubbles at a rate of 3 to 10% by volume. Do.

When the bubble content is less than 3% by volume, the adhesiveness when the temperature is changed to a low temperature is not improved. When it exceeds 10% by volume, the cohesive force of the pressure-sensitive adhesive film itself is reduced. However, the adhesion at room temperature is impaired.

The diameter of the bubble is 0.05 to
It is desirable to set the range to 0.5 mm. 0.05mm
In the case of bubbles less than, after the strain is applied to the adhesive film, the ratio of remaining bubbles may be extremely reduced,
If it exceeds mm, the air bubbles become too large, and a portion having extremely low cohesive force is formed in a part of the adhesive film, whereby the physical properties may be deteriorated.

In order to contain the above-mentioned air bubbles, the above-mentioned photo-polymerizable composition is foamed at the time of photopolymerization, and the foamed composition is polymerized by the above-mentioned photo-polymerization process. Further, a foaming agent such as dicarboxylic diimide may be mixed in the composition, foamed, and photopolymerized. further,
The pressure-sensitive adhesive foamed by the above-described method may be mixed with the non-foamed photopolymerizable composition and photopolymerized to form a pressure-sensitive adhesive tape.

Examples of a method for bubbling the photopolymerizable composition prior to polymerization include a method of introducing a gas into the photopolymerizable composition at a high speed and a method of adding a surfactant and stirring. .

Preferably, a method of adding a surfactant to the photopolymerizable composition and stirring the mixture is used. The surfactant preferably has an HLB value of 5 to 18, more preferably 6 to 15.

The HLB value of a surfactant is a value indicating the balance between lipophilicity and hydrophilicity of a surfactant, and is determined by the following equation. HLB value = W / 5, where W = 100 × Mw / M where M: molecular weight of surfactant, Mw: molecular weight of hydrophilic part of surfactant.

When the HLB value is in the range of 5 to 18, bubbles having an average diameter in the range of 0.05 to 0.5 mm can be uniformly dispersed in the adhesive film. As described above, those having an HLB value in the range of 5 to 18 are preferably used as described above, and examples thereof include nonionics such as polyoxyethylene phenyl ether, polyoxyethylene lauryl ether, and polyoxyethylene dodecyl phenyl ether. A surfactant is preferably used. However, other cationic surfactants such as polyamine-based polymer compounds and anionic surfactants such as phosphate ester-type surfactants are also preferably used as long as the HLB value is within the above range.

The proportion of the surfactant used is preferably in the range of 0.1 to 2 parts by weight based on 100 parts by weight of the total of the acrylic (meth) acrylate and the polar group-containing vinyl monomer. An adhesive film containing bubbles at a ratio of 3 to 10% by volume can be reliably obtained.

In the production of the pressure-sensitive adhesive tape according to the present invention, a foamy pressure-sensitive adhesive film containing 3 to 10% by volume of bubbles is obtained as described above. A tape may be constituted, or a pressure-sensitive adhesive tape with a substrate obtained by laminating the above-mentioned foamy pressure-sensitive adhesive film on a conventionally used film for a pressure-sensitive adhesive tape substrate may be used.

In the method for producing a pressure-sensitive adhesive tape according to the present invention, an appropriate tackifier or filler is added to the photopolymerizable composition in addition to the essential components described above, as long as the object of the present invention is not impaired. May be.

As the tackifier, rosin resin,
Modified rosin resin, terpene resin, terpene phenolic resin, C5 or C9 petroleum resin, cumarone resin,
Alternatively, these hydrogenated products can be used alone or in combination of two or more.

As the inorganic filler, for example, fine particles or hollow fine particles having an average particle diameter of 1 to 150 μm can be used.
Inorganic hollow fine particles such as silane balloons and fly ash balloons; organic hollow fine particles made of methyl polymethacrylate, acrylonitrile-vinylidene chloride copolymer, polystyrene, phenol resin, etc .; inorganic fine particles such as glass beads, silica beads, synthetic mica; polypropylene, etc. Organic fine particles.

(Function) In the method for producing a pressure-sensitive adhesive tape according to the present invention, an alkyl (meth) acrylate, a vinyl monomer having a polar group, a reactive monomer having two or more reactive double bonds in a molecule, and photopolymerization initiation Using a photopolymerizable composition containing an agent, while photopolymerizing the photopolymerizable composition,
3 to 10% by volume by bubbling the photopolymerizable composition
To obtain a bubble-type pressure-sensitive adhesive film containing air bubbles. In this case, each of the above alkyl (meth) acrylates and polar group-containing vinyl monomers has a mixed composition of Fedors
Has a theoretical solubility parameter of 10.0 to 15.0 (ca).
1 / cm ³ ) ^1/2 , the surface polarity of the resulting pressure-sensitive adhesive film is increased, which is sufficient for an adherend having a highly polar surface such as a metal. It exhibits room temperature adhesive strength.

Further, since the bubbles are contained at a rate of 3 to 10% by volume, even if the temperature of the polymer constituting the adhesive film increases due to the low temperature, the temperature change of the bubbles does not affect the polymer. And the overall flexibility is increased by the bubbles, so that the adhesive strength when the temperature is changed to low is increased.

[0043]

The present invention will be more specifically described below with reference to non-limiting examples.

Example 1 85 parts by weight of butyl acrylate, 15 parts by weight of acrylic acid, 0.2 parts by weight of hexanediol diacrylate as a crosslinking agent, and 1-hydroxycyclohexyl phenyl ketone 1 as a photopolymerization initiator
Parts by weight into a dissolution tank, and 0.2 parts by weight of polyoxyethylene nonyl phenyl ether (manufactured by Daiichi Kogyo Seiyaku Co., Ltd., trade name: Neugen EA80, HLB value = 10) as a surfactant, and blow nitrogen. It stirred for 10 minutes while putting. Thereafter, the above composition was subjected to release-treated PET.
It was applied on the film so that the thickness after polymerization became 2.0 mm. Next, light of 2.0 mW was irradiated for 10 minutes by a chemical lamp and photopolymerized to prepare a pressure-sensitive adhesive film.
The weight-average molecular weight of this pressure-sensitive adhesive was 800,000.

Example 2 A polyoxyethylene nonylphenyl ether-based surfactant (Daiichi Kogyo Seiyaku Co., Ltd., trade name: Neugen EA140, HLB value = 14) was used as the surfactant. In the same manner as in Example 1, a pressure-sensitive adhesive film was produced. The weight-average molecular weight of this pressure-sensitive adhesive was 810,000.

Example 3 A pressure-sensitive adhesive film was obtained in the same manner as in Example 1, except that the mixing ratio of Neugen EA80 was changed to 1.5 parts by weight. The weight-average molecular weight of this pressure-sensitive adhesive was 760,000.

Comparative Example 1 As a surfactant, a polyoxyethylene lauryl ether-based surfactant (manufactured by Daiichi Kogyo Seiyaku Co., Ltd., trade name: Neugen YX400, HLB value = 2)
A pressure-sensitive adhesive film was obtained in the same manner as in Example 1, except that 0) was used. The weight-average molecular weight of this pressure-sensitive adhesive was 780,000.

(Comparative Example 2) Except that a polyoxyethylene dodecylphenyl ether-based surfactant (manufactured by Daiichi Kogyo Seiyaku Co., Ltd., trade name: Neugen EA33, HLB value = 4) was used as the surfactant. In the same manner as in Example 1, a pressure-sensitive adhesive film was obtained. The weight-average molecular weight of this pressure-sensitive adhesive was 780,000.

(Comparative Example 3) The mixing ratio of the surfactant was set at 0.
A pressure-sensitive adhesive film was obtained in the same manner as in Example 1 except that the amount was changed to 05 parts by weight. The weight-average molecular weight of this pressure-sensitive adhesive was 830,000.

(Comparative Example 4) The mixing ratio of the surfactant was 4.
A pressure-sensitive adhesive film was obtained in the same manner as in Example 1, except that the amount was changed to 0 parts by weight. The weight-average molecular weight of this pressure-sensitive adhesive was 680,000.

Comparative Example 5 95 parts by weight of 2-ethylhexyl acrylate, 5 parts by weight of acrylic acid, 0.2 parts by weight of hexanediol diacrylate, and 1 part by weight of 1-hydroxy-cyclohexyl phenyl ketone as a photopolymerization initiator were dissolved in a dissolving tank. And a polyoxyethylene nonylphenyl ether-based surfactant (manufactured by Daiichi Kogyo Seiyaku Co., Ltd., trade name: Neugen EA80, HLB value = 1)
0) 4.0 parts by weight were added, and a pressure-sensitive adhesive film was prepared in the same manner as in Example 1 below. The weight-average molecular weight of this pressure-sensitive adhesive was 650,000.

(Evaluation) With respect to each of the pressure-sensitive adhesive films obtained in Examples and Comparative Examples, the adhesive force and the bubble content at 23 ° C. and -10 ° C. were measured in the following manner.

Adhesive force at 23 ° C. and -10 ° C .: At each temperature, a steel plate polished with a # 280 sandpaper is lengthened from one end of the pressure-sensitive adhesive film by 100 to 20 mm.
A 0 mm portion is placed, and a 2 kg roller is reciprocated one time from the back side and adhered. After 5 minutes, the other end of the pressure-sensitive adhesive film is 180 degrees at a speed of 300 mm / min with a tensile tester under each temperature condition. Peeling was performed, and the peeling resistance at that time was measured and defined as the adhesive strength (gf / 25 mm width).

Bubble content: A pressure-sensitive adhesive film having a thickness of 2.0 mm was prepared in the same manner as in each of Examples and Comparative Examples except that no surfactant was used. This was a standard product for Examples and Comparative Examples. Also,
The pressure-sensitive adhesive films obtained in each of the examples and comparative examples were used as test pieces. The standard product and the test product were
It was cut into a size of 50 mm square and its weight was measured.
Next, the weight of the test piece was divided by the weight of the standard product, subtracted from 1, and the bubble content was determined by percentage.

The above weight-average molecular weight is determined by dissolving a pressure-sensitive adhesive in tetrahydrofuran, leaving it for 24 hours, and then removing the impurities from the sample solution by gel permeation chromatography, using a refractive index based on standard polyethylene. This is a value measured using a detector.

The above evaluation results are shown in Table 1 below together with the theoretical solubility parameter sp. The theoretical solubility parameter sp is a theoretical solubility parameter of a mixed composition of an alkyl (meth) acrylate and a polar group-containing vinyl monomer when blended in accordance with the above Examples and Comparative Examples, and was measured by the method described above. Value.

[0057]

[Table 1]

[0058]

According to the method for producing a pressure-sensitive adhesive tape of the present invention, an alkyl (meth) acrylate, a polar group-containing vinyl monomer, a reactive monomer having two or more reactive double bonds in a molecule, and a photopolymerization start And a composition comprising an alkyl (meth) acrylate and a vinyl monomer having a polar group so that the theoretical solubility parameter of Fedors is in the range of 10.0 to 15.0 (cal / cm ³ ) ^1/2. A foamable pressure-sensitive adhesive film containing 3 to 10% by volume of bubbles is obtained by bubbling and photopolymerizing a photopolymerizable composition containing a (meth) acrylate and a vinyl monomer having a polar group, Since the above-mentioned theoretical solubility parameter is within the above-mentioned specific range, it has excellent adhesion to a highly polar surface such as a metal at normal temperature. In addition, since it contains 3 to 10% by volume of air bubbles, the adhesiveness when the temperature is changed to a low temperature of 0 ° C. or less is also sufficiently large.

Therefore, it is possible to provide an adhesive tape which is suitable for sticking to an adherend having a highly polar surface such as a metal and has a small change in adhesive force due to a temperature change to a low temperature. .

Claims (1)

[Claims] 1. An alkyl (meth) acrylate, a vinyl monomer having a polar group, and a reactive double bond in a molecule.
Including a reactive monomer and a photopolymerization initiator having at least one
The composition comprising an alkyl (meth) acrylate and a vinyl monomer having a polar group has a theoretical solubility parameter of Fedors of 10.0 to 15.0 (cal / c).
m ³ ) By bubbling a photopolymerizable composition containing an alkyl (meth) acrylate and a vinyl monomer having a polar group so as to be in the range of ^1/2 , and photopolymerizing, 3 to 10% by volume of A method for producing a pressure-sensitive adhesive tape, which comprises obtaining a cellular pressure-sensitive adhesive film containing bubbles.