JP2001262093A - Adhesive tapes for electronic device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an adhesive tape for both sides and adhesive sheets which reduce limitlessly possibility of generating corrosion of the inside of an electronic device, poor movement and error operation, since they are used for adhesion to a cover material of the electronic device and different members of the inside of the electronic device, do not contain a silicone resin composition in a mold-releasing layer and regulate an impurity amount of an ionic impurity, etc., in an extremely low level while having the good mold-releasing property of a separated liner. SOLUTION: A double-sided adhesive tape and adhesive sheets use a release liner consisting of a mixture of polyethylene and an ethylene-propylene copolymer and use an acrylate copolymer as a man component wherein the surface tension is not less than 40 mN/m (23 deg.C), an amount of a volatile organic compound generated when heating an adhesive at 120 deg.C is not more than 10 μg/cm2, and an amount of each ionic impurity in the adhesive is not more than 0.1 μg/cm2, respectively.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention is mainly used for bonding a cover material of an electronic device or various members inside the electronic device. The release layer of the release liner does not contain a silicone resin composition. The present invention relates to a double-sided pressure-sensitive adhesive tape and a pressure-sensitive adhesive sheet having excellent release properties and having extremely low levels of impurities such as volatile organic compounds and ionic impurities in a pressure-sensitive adhesive.

[0002]

2. Description of the Related Art Double-sided adhesive tapes and adhesive sheets are
Due to its ease of handling and good adhesive properties, it is widely used in various industries. In the field of electronic devices, many double-sided pressure-sensitive adhesive tapes and pressure-sensitive adhesive sheets are used for bonding various members. Many conventional double-sided pressure-sensitive adhesive tapes and pressure-sensitive adhesive sheets, in order to obtain good release properties of the release liner,
For the release layer, a silicone resin composition having a small surface tension is used. In addition, the amount of impurities such as volatile organic compounds and ionic impurities is suppressed to a relatively low level within a range where there is no practical problem, but even an extremely small amount of impurities may cause malfunction or the like. It is not designed to be a very low level, which is sufficient for equipment use. In the field of electronic devices, with the recent miniaturization of the inside of electronic devices, double-sided tapes and pressure-sensitive adhesive sheets with extremely low levels of impurities have been demanded.

[0003]

When a conventional double-sided pressure-sensitive adhesive tape or pressure-sensitive adhesive sheet using a silicone-based resin composition for a release layer of a release liner is used for electronic equipment, the silicone-based resin composition becomes The phenomenon of transfer to the adhesive layer occurs, which is a factor of generating siloxane gas, which may cause corrosion, malfunction, and malfunction inside the electronic device.

[0004] Therefore, double-sided pressure-sensitive adhesive tapes and pressure-sensitive adhesive sheets used in electronic equipment applications do not contain a silicone-based resin composition in the pressure-sensitive adhesive composition, and also include a silicone-based resin in a release layer of a release liner. It is desirable not to use and contain the composition.

As the release layer other than the silicone resin composition, there are a fluorine resin, an alkyd resin, a polyvinyl carbamate resin and an olefin resin. However, the fluorine-based resin has a low surface tension like the silicone-based resin composition but has a relatively high modulus of elasticity. Therefore, the anchoring to the base paper or the base film is insufficient and the base resin or the base film easily falls off. During the manufacture of such a kind, there is a problem that when the release liner passes through the roll, the release liner is likely to fall off and cause a release failure. Alkyd resins and polyvinyl carbamate resins are
The resin used for the release layer has a relatively high surface tension, and when used for an acrylic pressure-sensitive adhesive, the release force becomes extremely heavy, which is not suitable for practical use. Some alkyd resins control the release force by adding a silicone resin composition, but are not suitable for use in electronic components. General olefin resins also have a relatively high surface tension, and it is difficult to obtain a suitable releasing force.

[0006] In the conventional pressure-sensitive adhesives used for double-sided pressure-sensitive adhesive tapes and pressure-sensitive adhesive sheets, sufficient attention has not been paid to the amount of impurities such as volatile organic compounds and ionic impurities. If it is contained, it may cause a corrosive gas to be generated, and the corrosive gas and metallic ions may cause corrosion, malfunction, or malfunction inside the electronic device.

The present invention solves the above-mentioned problems, and does not contain a silicone resin composition in a release layer of a release liner used for bonding a cover material of an electronic device or various members inside the electronic device. The object of the present invention is to provide double-sided pressure-sensitive adhesive tapes and pressure-sensitive adhesive sheets having excellent release properties, and having an extremely low level of impurities such as volatile organic compounds and ionic impurities in the pressure-sensitive adhesive. I do.

[0008]

Means for Solving the Problems The present inventors have found that the release layer of the release liner is made of a mixture of polyethylene and an ethylene-propylene copolymer, and the surface tension of the pressure-sensitive adhesive is 40 or less.
With a double-sided pressure-sensitive adhesive tape and a pressure-sensitive adhesive sheet characterized by containing an acrylate copolymer having a mN / m (23 ° C.) or higher as a main component, the release layer does not contain a silicone-based resin composition and is excellent. It has been found that one of the above-mentioned problems of having a good releasability can be solved. Further, the amount of volatile organic compounds generated when the pressure-sensitive adhesive is heated at 120 ° C. for 1 hour is 10 μg / cm ² or less, and F ⁻ , C
_{^{l -, Br -, NO 2}} -, NO 3 -, PO 4 3-, SO
₄ Each ^2- anions and _{^{NH 4 +, Na +, K}} +, M
The amount of ionic impurities of each g ²⁺ cation is 0.
By using an adhesive that is 1 μg / cm ² or less,
The present inventors have found that one of the above-mentioned problems can be solved, and have accomplished the present invention.

In the release liner used in the present invention, the release layer comprises a mixture of polyethylene and an ethylene-propylene copolymer. The release force of the release liner is greatly affected by the surface tension and elastic modulus of the release layer, and the lower the value of both, the better the release force is not too heavy in the normal temperature range when using normal double-sided adhesive tapes. Value is obtained. In the olefin group having a higher surface tension than the silicone resin composition,
Polyethylene having a relatively low surface tension and elastic modulus in the olefin group is advantageous as the release layer. However, with polyethylene alone, a sufficiently good release force cannot be obtained with respect to the pressure-sensitive adhesive containing an acrylate copolymer as a main component. Thus, it has been found that, since the degree of crystallinity is lower than that of polyethylene, by mixing an ethylene-propylene copolymer having a low elastic modulus into polyethylene, a suitable releasing force within a practical range can be obtained. In addition, the ethylene-propylene copolymer used in the present invention includes divinylbenzene, 1,3 as a third component monomer having an unsaturated bond.
Terpolymers obtained by copolymerizing 4-hexadiene, dicyclopentadiene, cyclooctadiene or the like may be used. Ethylene-propylene copolymer alone has low elastic modulus and insufficient heat resistance, and in the casting method in which an adhesive solution is applied directly to a release liner during production and dried, the release force is increased by heat during drying. This tends to limit the production method.

The molecular weight and the density of each of the polyethylene and the ethylene-propylene copolymer used in the present invention are not particularly limited as long as they have a sufficient film-forming property for forming a release layer.

The release layer is obtained by a known manufacturing method such as a film forming method using a T-die extruder. The release layer is provided on a base paper or a base film of a release liner by extrusion lamination or the like. Not done.
When using a T-die extruder, the extrusion temperature is from 250 ° C to 35 ° C.
Molding is suitably performed in the range of 0 ° C. Further, only these release layers can be used as a release liner. The surface of the release layer may be appropriately subjected to a surface treatment such as a mirror treatment and a mat treatment as needed. The thickness of the release layer is set to a desired thickness, but is preferably set to a thickness of 5 to 150 μm. Alternatively, the thickness of the release liner is also set to a desired thickness, but is preferably set to 10 to 200 μm in consideration of proper processing of the product and workability at the time of peeling. Examples of the base paper used for the release liner include high-quality paper, kraft paper, glassine paper, parchment paper, and the like, and known papers can be used. Further, known plastic films such as a polyester film can be used as the base film.

The pressure-sensitive adhesive layer used in the present invention is characterized by comprising a pressure-sensitive adhesive mainly composed of an acrylate copolymer having a surface tension of 40 mN / m (23 ° C.) or more. When the surface tension is lower than 40 mN / m (23 ° C.), even when the above-described release layer is used, the release force is increased and workability is impaired. Further, the pressure-sensitive adhesive layer has a volatile organic compound amount of 10 μg / cm ² or less when the pressure-sensitive adhesive is heated at 120 ° C. for 1 hour, and F ⁻ ,
_{^{Cl -, Br -, NO 2}} -, NO 3 -, PO 4 3-, S
O ₄ each ^2- anions and _{^{NH 4 +, Na +, K}} +,
The ionic impurity amount of each Mg ²⁺ cation is 0.1 μg / cm ² or less. The acrylate copolymer is composed of a (meth) acrylate copolymer and an unsaturated monomer copolymerizable therewith.

Examples of (meth) acrylic esters include n-butyl (meth) acrylate, isobutyl (meth) acrylate, sec-butyl (meth) acrylate, tert-butyl (meth) acrylate, pentyl (meth) acrylate, Isopentyl (meth) acrylate, hexyl (meth) acrylate, cyclohexyl (meth) acrylate, heptyl (meth) acrylate, octyl (meth) acrylate, isooctyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, nonyl (meth) acrylate, Examples include isononyl (meth) acrylate, decyl (meth) acrylate, perdecyl (meth) acrylate, and tridecyl (meth) acrylate.

The acrylate copolymer used for the conventional adhesive tapes is designed so that various unsaturated monomers can be copolymerized and exhibit properties suitable for use. Unsaturated monomers copolymerizable with the (meth) acrylic acid ester used in (1) are limited in terms of the types of monomers that can cause ionic impurities from the viewpoint of suppressing the amount of ionic impurities to an extremely low level.

Examples of the unsaturated monomer copolymerizable with the (meth) acrylate used in the present invention include alkyl (meth) acrylates other than those exemplified above as alkyl (meth) acrylates;
(Meth) acrylates having an ether group and the like; aliphatic unsaturated (di) carboxylic acids such as (meth) acrylic acid and fumaric acid; aliphatic unsaturated hydrocarbons such as ethylene and butadiene; styrene, α-methylstyrene And the like; aromatic unsaturated hydrocarbons such as vinyl ethers; vinyl esters such as vinyl acetate;

In the present invention, the unsaturated monomers copolymerizable with the (meth) acrylic acid ester whose use is restricted include (meth) acrylates having an amino group and an amide group; and aliphatic unsaturated carbons such as vinyl chloride. Halogen-substituted hydrogens; cyanide compounds such as acryloetril;

The acrylate copolymer in the present invention can be obtained by a known polymerization method such as a solution polymerization method, an emulsion polymerization method, a bulk polymerization method, a suspension polymerization method, and is not limited to a production method. In the suspension polymerization method, an emulsifier and a stabilizer may remain in the pressure-sensitive adhesive, which is not preferable from the viewpoint of suppressing the amount of impurities to a low level, and also has a bad influence on the adhesive properties. In the bulk polymerization method, it is possible to take a washing step after polymerization, or in the solution polymerization method, at the final stage of polymerization, to add a polymerization initiator to eliminate residual monomers,
By using a technique of setting the polymerization temperature higher and azeotropically eliminating the residual monomer together with the polymerization solvent,
It is preferable to use bulk polymerization or solution polymerization because the amount of volatile organic compounds in the adhesive tapes can be suppressed to a lower level.

The thermal polymerization initiator used in the acrylate copolymer of the present invention is not particularly limited, and a known one can be used. However, from the viewpoint of suppressing the amount of ionic impurities to an extremely low level, ionic It is preferable to use an organic peroxide-based compound rather than an azo compound-based compound containing many nitrile groups which are highly likely to be a factor for generating impurities. Examples of the organic peroxide-based thermal polymerization initiator include benzoyl peroxide, cumene hydroperoxide, diisopropylperoxydicarbonate, di-n-propylperoxydicarbonate, dipropionyl peroxide, t-butylperbenzoate and the like. There is. Examples of the azo compound-based thermal polymerization initiator include 2,2′-azobisisobutyronitrile, 2,2′-azobis (2-methylbutyronitrile), 1,1′-azobis (cyclohexane 1-carbo Nitrile), dimethyl 2,2'-azobis (2-methylpropionate), dimethyl 2,2'azobisisobutyrate, and the like.

The pressure-sensitive adhesive of the present invention has an acrylic ester copolymer as a main component and is crosslinked by a crosslinking agent. As the cross-linking agent used in the present invention, there are isocyanate compounds and epoxy resins, and metal chelates that may be used in conventional pressure-sensitive adhesives are limited in use from the viewpoint of suppressing the amount of ionic impurities to an extremely low level, Preferably, an epoxy resin is used. In addition, various additives such as a tackifying resin, an antioxidant, and a filler may be appropriately added to the pressure-sensitive adhesive within a range in which the amount of volatile impurities and the amount of ionic impurities are within the range described in the claims.

The weight average molecular weight of the acrylate copolymer used in the present invention is not particularly limited, but is preferably 300,000 to 1.2 million. If the weight average molecular weight of the acrylate copolymer is less than 300,000,
When an ordinary amount of the crosslinking agent is added, the cohesive strength of the pressure-sensitive adhesive is insufficient and is often unsuitable for practical use. When the amount of the cross-linking agent is increased, the adhesive properties are impaired. Also, when the weight average molecular weight of the acrylate copolymer is larger than 1.2 million, the adhesive properties are impaired.

The pressure-sensitive adhesive of the present invention has a surface tension of 40 mN /
m (23 ° C.) or higher, but the above-mentioned (meth) acrylates having a hydroxyl group, an ether group and the like; aliphatic unsaturated (di) carboxylic acids such as (meth) acrylic acid and fumaric acid By increasing the copolymerization amount of a polar functional group-containing monomer that can be used in the present invention, a high surface tension can be obtained. The copolymerization amount of the functional group-containing monomer is not particularly limited, and is appropriately set within a range where the surface tension of the pressure-sensitive adhesive is 40 mN / m (23 ° C.) or more and the adhesive property is not impaired. Preferably, based on 100 parts by weight of the (meth) acrylate copolymer,
It is preferable to copolymerize in the range of 3 to 50 parts by weight of the functional group-containing monomer. When the copolymerization amount of the functional group-containing monomer is less than 3 parts by weight, the surface tension of the pressure-sensitive adhesive is 40 mN / m (23
℃), polyethylene and polyethylene-
Even when a mixture of the polypropylene copolymer is used, the releasing force is increased and the workability becomes difficult. When the copolymerization amount of the functional group-containing monomer is more than 50 parts by weight, the tackiness of the pressure-sensitive adhesive is impaired and the adhesive properties are deteriorated.

The surface tension of the pressure-sensitive adhesive may be adjusted not only by the amount of the functional group-containing monomer in the (meth) acrylate copolymer but also by the addition of a tackifier resin or a filler. .

The thickness of the pressure-sensitive adhesive used in the present invention is not particularly limited, but is preferably from 5 to 150 μm. When the thickness of the pressure-sensitive adhesive is less than 5 μm, the adhesive properties are often insufficient, and when the thickness is more than 150 μm, workability and the like are deteriorated when punching a product.

The present invention is not limited to the constitution of the double-sided pressure-sensitive adhesive tape and the pressure-sensitive adhesive sheet. In the double-sided pressure-sensitive adhesive tape, a release layer is provided on both sides of the release liner, and a single release liner is used to form a roll. Specifications and specifications in which a release liner is provided for each of the adhesive surfaces can be used. In the pressure-sensitive adhesive sheets, a pressure-sensitive adhesive layer is provided on a base material such as a polyester film, paper, or foam,
The release liner of the present invention is provided on the surface opposite to the substrate.

The method for producing a double-sided pressure-sensitive adhesive tape or pressure-sensitive adhesive sheet in the present invention is not particularly limited, and can be obtained by a known method. Examples include a transfer method in which an adhesive solution is applied to a release liner and dried, and a transfer method in which the adhesive is applied to a substrate such as a nonwoven fabric or a polyester film, or an adhesive solution is directly applied to a nonwoven fabric or a polyester film and dried to form a release liner. There is a direct method of bonding. In the present invention, in order to suppress the amount of volatile organic compounds to a low level, when using an adhesive solution, as a solvent, a solvent having a lower boiling point than toluene or the like ethyl acetate or the like is used as a single composition, and drying conditions are used. It is also preferable that the maximum temperature is 100 ° C. or higher.

[0026]

BEST MODE FOR CARRYING OUT THE INVENTION A release layer according to the present invention uses a release liner made of a mixture of polyethylene and ethylene-propylene copolymer, and has an acrylic ester copolymer as a main component and a surface tension of 40 mN / m. (23 ° C.) or more, the amount of volatile organic compounds generated when the adhesive is heated at 120 ° C. for 1 hour is 10 μg / cm ² or less, and the amount of each ionic impurity in the adhesive is 0.1 μg / cm ^2.
By using a pressure-sensitive adhesive characterized by the following, it is used for the bonding of electronic device cover materials and various members inside the electronic device, and the generation factors of siloxane gas, corrosive gas, metallic ions, etc. Therefore, a double-sided pressure-sensitive adhesive tape and a pressure-sensitive adhesive sheet having very low possibility of causing corrosion, malfunction, and malfunction inside the electronic device and having good release properties can be obtained.

[0027]

Next, the present invention will be described with reference to examples.

Example 1 As a release liner, polyethylene (Sumikasen L571 manufactured by Sumitomo Chemical Co., Ltd.) was used.
5 ", a density of 0.93 g / cm ³ ) and a mixture of 70 parts by weight of an ethylene-propylene copolymer (Ube Tack UT3385 manufactured by Ube Lexen, density 0.86 g / cm ³ ) having a thickness of 20 μm. The release layer used was obtained by providing a release layer on a polyester film having a thickness of 50 μm by an extrusion lamination method. As an adhesive solution, 90 parts by weight of n-butyl acrylate, 10 parts by weight of acrylic acid, and 0.2 parts by weight of 2-hydroxyethyl methacrylate were polymerized by a solution polymerization method using benzoyl peroxide as a thermal polymerization initiator. Weight average molecular weight 6
A solution obtained by dissolving 100,000 acrylate copolymers in an ethyl acetate solvent at a nonvolatile content of 40% was used. An epoxy resin is added as a crosslinking agent to the pressure-sensitive adhesive solution, applied on the release liner, and dried at 105 ° C. for 5 minutes,
An adhesive is provided with a thickness of 50 μm, and a base material of 100 μm
An adhesive tape was obtained by laminating a polyester film having a thickness.

Example 2 Example 1 was applied to a release liner.
The same one was used. As the pressure-sensitive adhesive solution, 88 parts by weight of 2-ethylhexyl acrylate by a solution polymerization method,
12 parts by weight of acrylic acid and 0.2 parts by weight of 2-hydroxyethyl methacrylate were added to dimethyl 2,2 as a thermal polymerization initiator.
An acrylic acid ester copolymer having a weight average molecular weight of 700,000 polymerized using 2'-azobis (2-methylpropionate) was dissolved in an ethyl acetate solvent at a nonvolatile content of 40%. An epoxy resin was added as a cross-linking agent to the pressure-sensitive adhesive solution to obtain a pressure-sensitive adhesive tape in the same manner as in Example 1.

Example 3 As a release liner, polyethylene (Sumikasen L571 manufactured by Sumitomo Chemical Co., Ltd.) was used.
5 ", 50 parts by weight of a density 0.93 g / cm ³ ) and 50 parts by weight of an ethylene-propylene copolymer (" Ubetac UT3385 "manufactured by Ube Lexen Co., Ltd., density 0.86 g / cm ³ ) having a thickness of 20 μm. The release layer used was obtained by providing a release layer on a polyester film having a thickness of 50 μm by an extrusion lamination method. Using the above release liner, an adhesive tape was obtained by the same adhesive solution and production method as in Example 1.

(Comparative Example 1) Polyethylene (Sumikasen L571 manufactured by Sumitomo Chemical Co., Ltd.) was used as a release liner.
5 ", a thickness of only 0.93 g / cm ³ )
A release layer having a thickness of 5 μm was formed by extrusion lamination to a thickness of 5 μm.
What was obtained by providing on a 0-micrometer polyester film was used. Using the above release liner, an adhesive tape was obtained by the same adhesive solution and production method as in Example 1.

(Comparative Example 2) Example 1 was applied to a release liner.
The same one was used. As the pressure-sensitive adhesive solution, 85 parts by weight of n-butyl acrylate, 10 parts by weight of acrylic acid, 5 parts by weight of acrylonitrile, and 0.2 parts by weight of 2-hydroxyethyl methacrylate were added to a thermal polymerization initiator by a solution polymerization method. An acrylic acid ester copolymer having a weight average molecular weight of 600,000 polymerized using '-azobisisobutyronitrile and dissolved in an ethyl acetate solvent at a nonvolatile content of 40% was used. An isocyanate compound is added as a cross-linking agent to the pressure-sensitive adhesive solution, applied on the release liner and dried at 105 ° C. for 5 minutes to form a pressure-sensitive adhesive having a thickness of 50 μm.
m, and a 100-μm-thick polyester film as a substrate was laminated to obtain an adhesive tape.

(Comparative Example 3) Example 1 was applied to a release liner.
The same one was used. As an adhesive solution, 99 parts by weight of n-butyl acrylate, 1 part by weight of acrylic acid, and 0.2 parts by weight of 2-hydroxyethyl methacrylate were polymerized by a solution polymerization method using benzoyl peroxide as a thermal polymerization initiator. A mixture of 90 parts by weight of an acrylate copolymer having a weight average molecular weight of 600,000 and 10 parts by weight of a rosin ester having a softening point of 110 ° C. dissolved in an ethyl acetate solvent at a nonvolatile content of 40% was used. An epoxy resin is added to the pressure-sensitive adhesive solution as a crosslinking agent, applied on the release liner, dried at 105 ° C. for 5 minutes, provided with a pressure-sensitive adhesive with a thickness of 50 μm, and adhered to a 100 μm-thick polyester film as a substrate. Together, an adhesive tape was obtained.

(Comparative Example 4) Example 1 was applied to a release liner.
The same one was used. As the pressure-sensitive adhesive solution, 85 parts by weight of n-butyl acrylate, 10 parts by weight of acrylic acid, 5 parts by weight of acrylonitrile, and 0.2 parts by weight of 2-hydroxyethyl methacrylate were added to a thermal polymerization initiator by a solution polymerization method. An acrylic acid ester copolymer having a weight average molecular weight of 600,000 polymerized using '-azobisisobutyronitrile and dissolved in a toluene solvent at a nonvolatile content of 40% was used. An isocyanate compound is added to the pressure-sensitive adhesive solution as a cross-linking agent, applied on the release liner and dried at 90 ° C. for 5 minutes. The pressure-sensitive adhesive is provided with a thickness of 50 μm, and a 100 μm-thick polyester film as a substrate is applied. Together, an adhesive tape was obtained.

(Surface Tension of Adhesive) The method of measuring the surface tension of the adhesive is as follows. A smooth pressure-sensitive adhesive film without foaming is provided on a film such as a polyester film, and a known pressure is applied to this adhesive surface at 23 ° C. Were dropped, and the contact angles were measured. From the proportional relationship between the surface tension of the liquid and the contact angle, the critical surface tension when the contact angle becomes 0 °
Obtained as the surface tension of the adhesive.

(Release Force of Release Liner) The prepared pressure-sensitive adhesive tape was cut into a width of 50 mm, and the stress when the release liner was peeled from the pressure-sensitive adhesive tape in a T-shape at a pulling speed of 300 mm / min was measured using a tensile tester. It measured using. The releasing force range in which the workability in the normal temperature range is good is 1.30 N / 50.
mm, and when it is larger than 1.30 N / 50 mm, workability is impaired. ○ ・ ・ ・ Release force is 1.30N / 50mm or less × ・ ・ ・ Release force is greater than 1.30N / 50mm

(Amount of Volatile Organic Compound in Adhesive Tape) Peeling liner of 10 cm ² of adhesive tape was peeled off, and 22 m
After collecting in a 1 l sample bottle, sealing, and heating at 120 ° C. for 1 hour, 1 ml of the gas phase was injected into the gas chromatograph with the heating constant, and the amount of volatile organic compounds was measured.・ ・ ・: The amount of volatile organic compound is 10 μg / cm ² or less ×: The amount of volatile organic compound is more than 10 μg / cm ²

(Amount of ionic impurities in the adhesive tape) The release liner of the adhesive tape 10 cm ² was peeled off, and pure water 15
g together with Teflon (registered trademark) pressure-resistant container.
Extraction under pressure was performed at 0 ° C. for 3 hours, followed by filtration. The filtrate was diluted, and F ⁻ , Cl ⁻ , Br ⁻ , and NO ₂ were measured by ion chromatography.
_{^{-, NO 3 -, PO 4}} 3-, SO 4 each ^2- anions and _{^{NH 4 +, Na +, K}} +, to determine the amount of each cation of ^{Mg 2+.}・ ・ ・: The amount of each of the above ions is 0.1 μg / cm ² or less ×: One or more of the above ions is 0.1 μg / cm ²
is more than

Using the pressure-sensitive adhesive tapes of Examples 1 to 3 and Comparative Examples 1 to 4, the above various evaluations were performed. The results are shown in Tables 1 and 2.

[0040]

[Table 1]

[0041]

[Table 2]

[0042]

According to the present invention, a cover material for electronic equipment,
Used for bonding various members inside electronic equipment, the release layer does not contain the silicone resin composition while having good release properties of the release liner, and volatile organic compounds and ions in the adhesive are not contained. Since the amount of impurities such as sexual impurities is suppressed to an extremely low level, it is possible to provide a double-sided pressure-sensitive adhesive tape and a pressure-sensitive adhesive sheet with an extremely low possibility of causing corrosion, malfunction, and malfunction inside the electronic device.

Claims (2)

[Claims] The release layer of the release liner is composed of a mixture of polyethylene and an ethylene-propylene copolymer, and is mainly composed of an acrylate ester copolymer having a surface tension of 40 mN / m (23 ° C.) or more. Double-sided pressure-sensitive adhesive tapes and pressure-sensitive adhesive sheets characterized by being used as components. 2. The amount of a volatile organic compound in an adhesive generated when the adhesive is heated at 120 ° C. for 1 hour is 10 μg / cm ^2.
The following and containing F ⁻ , Cl ⁻ , Br ⁻ , N
The amount of ionic impurities of each anion of O ₂ ⁻ , NO ₃ ⁻ , PO ₄ ³⁻ , SO ₄ ²⁻ and each cation of NH ₄ ⁺ , Na ⁺ , K ⁺ , and Mg ²⁺ is 0.1 μg / cm ² or less. The double-sided pressure-sensitive adhesive tape and pressure-sensitive adhesive sheets according to claim 1, wherein