JP6014781B1 - Adhesive tape and adhesive tape for fixing electronic device parts - Google Patents

Abstract

The present invention provides an adhesive tape that has excellent resistance to sebum and can maintain adhesive strength even when used on a part that is frequently touched by human hands, and an adhesive tape for fixing electronic device parts comprising the adhesive tape. To do. An adhesive tape having an adhesive layer made of an acrylic adhesive on at least one surface, wherein the adhesive layer swells after being immersed in oleic acid at 60 ° C. and a humidity of 90% for 24 hours. An adhesive tape having a rate of 100% or more and 130% or less. [Selection figure] None

Description

The present invention relates to a pressure-sensitive adhesive tape that has excellent resistance to sebum and can maintain adhesive strength even when used on a part that is frequently touched by human hands, and a pressure-sensitive adhesive tape for fixing electronic device parts comprising the pressure-sensitive adhesive tape. .

Conventionally, pressure-sensitive adhesive tapes have been widely used for fixing components in electronic devices. Specifically, for example, an adhesive tape is used to bond a cover panel for protecting the surface of a portable electronic device to a touch panel module or a display panel module, or to bond a touch panel module and a display panel module. ing. Such adhesive tapes used for fixing electronic device parts are required to have functions such as heat resistance, thermal conductivity, and impact resistance depending on the environment of the part used in addition to high adhesiveness (for example, patents) Literatures 1-3).

In recent years, electronic devices such as mobile phones, smart phones, and wearable terminals that are always worn or put on hand have become widespread due to the reduction in size, weight, and cost of electronic devices. Such portable electronic devices are frequently used and are operated with bare hands using a touch panel or the like. Therefore, when an adhesive tape is used on a part that is frequently touched, the adhesive tape is sebumed by sebum. There was a problem that it deteriorated and peeled off.

Japanese Patent Laying-Open No. 2015-052050 Japanese Patent Laying-Open No. 2015-021067 JP, 2015-12076, A

The present invention provides an adhesive tape that has excellent resistance to sebum and can maintain adhesive strength even when used on a part that is frequently touched by human hands, and an adhesive tape for fixing an electronic device component comprising the adhesive tape. The purpose is to provide.

The present invention is an adhesive tape having an adhesive layer made of an acrylic adhesive on at least one surface, and the adhesive layer swells after being immersed in oleic acid for 24 hours at 60 ° C. and a humidity of 90%. The pressure-sensitive adhesive tape has a rate of 100% or more and 130% or less.
The present invention is described in detail below.

As a result of intensive studies on the problem of peeling of the pressure-sensitive adhesive due to the above-mentioned sebum, the present inventors have been exposed to sebum by using an acrylic pressure-sensitive adhesive having a specific swelling ratio after being immersed in oleic acid. Even in such a case, it was found that the adhesive strength can be maintained, and the present invention has been completed.

The pressure-sensitive adhesive tape of the present invention has a pressure-sensitive adhesive layer made of an acrylic pressure-sensitive adhesive on at least one surface, and the pressure-sensitive adhesive layer swells after being immersed in oleic acid at 60 ° C. and a humidity of 90% for 24 hours. Is 100% or more and 130% or less.
When the oleic acid swelling rate of the pressure-sensitive adhesive layer is in the above range, the pressure-sensitive adhesive tape of the present invention exhibits high resistance to deterioration due to oleic acid, which is the main component of sebum, and is a part that is frequently touched by human hands. Even if it is a case where it uses for, peeling of an adhesive tape can be prevented. A preferable upper limit of the oleic acid swelling ratio is 120%, and a more preferable upper limit is 110%.
The “swelling ratio” in the present specification is a value expressed as a percentage of the weight of the pressure-sensitive adhesive after being immersed in oleic acid with respect to the weight of the pressure-sensitive adhesive before being immersed in oleic acid as in the following formula. It is.
Swelling ratio (% by weight) = (weight of pressure-sensitive adhesive after oleic acid immersion / weight of pressure-sensitive adhesive before oleic acid immersion) × 100

Examples of a method for obtaining an acrylic pressure-sensitive adhesive layer having an oleic acid swelling ratio in the above range include a method using a (meth) acrylate copolymer for the acrylic pressure-sensitive adhesive. Specifically, for example, (1) a method using an acrylic pressure-sensitive adhesive containing a (meth) acrylate copolymer having a structural unit derived from fluorine-containing (meth) acrylate, or (2) a carbon number of 2 or less The method of using the acrylic adhesive containing the (meth) acrylate copolymer containing the structural unit derived from the (meth) acrylate which has an alkyl group is mentioned. Hereinafter, the two types of acrylic pressure-sensitive adhesives will be described. In the present specification, (meth) acrylate means acrylate or methacrylate.

(1) Acrylic pressure-sensitive adhesive containing a (meth) acrylate copolymer having a structural unit derived from fluorine-containing (meth) acrylate The acrylic pressure-sensitive adhesive has a structural unit derived from fluorine-containing (meth) acrylate (meta ) Acrylate copolymer (hereinafter referred to as a fluorine-containing (meth) acrylate copolymer). The structural unit derived from fluorine-containing (meth) acrylate is obtained because fluorine itself exhibits high water and oil repellency, and sebum does not easily enter the molecular chain due to dense packing of fluorine atoms. High resistance to sebum can be imparted to the adhesive tape. Moreover, even if the said acrylic adhesive contains a fluorine-containing (meth) acrylate copolymer, the tackiness of the adhesive tape obtained can be maintained.

Examples of the fluorine-containing (meth) acrylate include 2,2,2-trifluoroethyl acrylate, 2- (perfluorohexyl) ethyl acrylate, 2,2,3,3,3-pentafluoropropyl acrylate, 2- (Perfluorobutyl) ethyl acrylate, 3-perfluorobutyl-2-hydroxypropyl acrylate, 3-perfluorohexyl-2-hydroxypropyl acrylate, 3- (perfluoro-3-methylbutyl) -2-hydroxypropyl acrylate, 1H , 1H, 3H-tetrafluoropropyl acrylate, 1H, 1H, 5H-octafluoropentyl acrylate, 1H, 1H, 7H-dodecafluoroheptyl acrylate, 1H-1- (trifluoromethyl) trifluoroethyl acrylate IH, IH, 3H-hexafluorobutyl acrylate, 1,2,2,2-tetrafluoro-1- (trifluoromethyl) ethyl acrylate. Among these, 2,2,2-trifluoroethyl acrylate is preferably used because of its particularly high resistance to sebum.

In the fluorine-containing (meth) acrylate copolymer, the content of the structural unit derived from the fluorine-containing (meth) acrylate is preferably 30% by weight, and preferably 80% by weight. It becomes easy to adjust the oleic acid swelling rate to the said range because content of the structural unit derived from the said fluorine-containing (meth) acrylate is 30 weight% or more. When the content of the structural unit derived from the fluorine-containing (meth) acrylate is 80% by weight or less, the pressure-sensitive adhesive does not become too hard, and a pressure-sensitive adhesive tape with more excellent adhesive force can be obtained. The minimum with more preferable content of the structural unit derived from the said fluorine-containing (meth) acrylate is 40 weight%, and a more preferable upper limit is 60 weight%.

The fluorine-containing (meth) acrylate copolymer preferably further contains a structural unit derived from (meth) acrylate having an alkyl group having 2 or less carbon atoms. When the fluorine-containing (meth) acrylate copolymer contains a structural unit derived from (meth) acrylate having an alkyl group having 2 or less carbon atoms, resistance to sebum can be further increased.

Examples of the (meth) acrylate having an alkyl group having 2 or less carbon atoms include methyl (meth) acrylate and ethyl (meth) acrylate. Among them, it is preferable to use ethyl acrylate because the pressure-sensitive adhesive does not become too hard and can be a pressure-sensitive adhesive tape with more excellent adhesive strength.

The content of the structural unit derived from the (meth) acrylate having an alkyl group having 2 or less carbon atoms in the fluorine-containing (meth) acrylate copolymer is not particularly limited, but a preferred lower limit is 15% by weight and a preferred upper limit. Is 40% by weight. When the content of the (meth) acrylate having an alkyl group having 2 or less carbon atoms is within the above range, resistance of the obtained adhesive tape to sebum can be further increased. The more preferable lower limit of the content of the structural unit derived from the (meth) acrylate having an alkyl group having 2 or less carbon atoms in the fluorine-containing (meth) acrylate copolymer is 20% by weight, and the more preferable upper limit is 30%. %.

The fluorine-containing (meth) acrylate copolymer preferably further contains a structural unit derived from a monomer having a crosslinkable functional group.
When the fluorine-containing (meth) acrylate copolymer contains a structural unit derived from the monomer having the crosslinkable functional group, the fluorine-containing (meth) acrylate copolymer chain is crosslinked when a crosslinking agent is used in combination. . At that time, the gel fraction and the swelling ratio can be adjusted by adjusting the degree of crosslinking.

Examples of the crosslinkable functional group include a hydroxyl group, a carboxyl group, a glycidyl group, an amino group, an amide group, and a nitrile group. Especially, since adjustment of the gel fraction of the said adhesive layer is easy, a hydroxyl group or a carboxyl group is preferable. Examples of the monomer having a hydroxyl group include (meth) acrylic acid esters having a hydroxyl group such as 4-hydroxybutyl (meth) acrylate and 2-hydroxyethyl (meth) acrylate.
As a monomer which has a carboxyl group, (meth) acrylic acid is mentioned, for example.
Examples of the monomer having a glycidyl group include glycidyl (meth) acrylate.
Examples of the monomer having an amide group include hydroxyethyl acrylamide, isopropyl acrylamide, dimethylaminopropyl acrylamide and the like.
Examples of the monomer having a nitrile group include acrylonitrile. These monomers having a crosslinkable functional group may be used alone or in combination.

Although content of the structural unit derived from the monomer which has the said crosslinkable functional group in the said fluorine-containing (meth) acrylate copolymer is not specifically limited, A preferable minimum is 1 weight% and a preferable upper limit is 5 weight%. When the content of the structural unit derived from the monomer having a crosslinkable functional group is in the above range, the swelling rate and gel fraction can be easily adjusted to the above range.

The fluorine-containing (meth) acrylate copolymer is within the range not inhibiting the effects of the present invention, and further, propyl acrylate, butyl acrylate, cyclohexyl acrylate, octyl acrylate, nonyl acrylate, isobornyl acrylate, benzyl acrylate, phenoxyethyl acrylate And a structural unit derived from vinyl acetate or the like.

The fluorine-containing (meth) acrylate copolymer preferably has a lower limit of 500,000 and an upper limit of 2,000,000 for the weight average molecular weight. When the weight average molecular weight of the fluorine-containing (meth) acrylate copolymer is in the above range, the resulting adhesive tape can be made more excellent in adhesive strength. The minimum with a more preferable weight average molecular weight of the said fluorine-containing (meth) acrylate copolymer is 600,000, and a more preferable upper limit is 1,200,000. The weight average molecular weight can be adjusted depending on the polymerization conditions (for example, the type or amount of the polymerization initiator, the polymerization temperature, the monomer concentration, etc.).

In order to synthesize the fluorine-containing (meth) acrylate copolymer, an acrylic monomer derived from the structural unit may be radically reacted in the presence of a polymerization initiator. The polymerization method is not particularly limited, and a conventionally known method can be used. Examples include solution polymerization (boiling point polymerization or constant temperature polymerization), emulsion polymerization, suspension polymerization, bulk polymerization and the like. Among these, solution polymerization is preferable because synthesis is simple.

When solution polymerization is used as the polymerization method, examples of the reaction solvent include ethyl acetate, toluene, methyl ethyl ketone, methyl sulfoxide, ethanol, acetone, diethyl ether and the like. These reaction solvents may be used alone or in combination of two or more.

The said polymerization initiator is not specifically limited, For example, an organic peroxide, an azo compound, etc. are mentioned. Examples of the organic peroxide include 1,1-bis (t-hexylperoxy) -3,3,5-trimethylcyclohexane, t-hexylperoxypivalate, t-butylperoxypivalate, 2,5 -Dimethyl-2,5-bis (2-ethylhexanoylperoxy) hexane, t-hexylperoxy-2-ethylhexanoate, t-butylperoxy-2-ethylhexanoate, t-butylperoxy Examples include isobutyrate, t-butylperoxy-3,5,5-trimethylhexanoate, and t-butylperoxylaurate. Examples of the azo compound include azobisisobutyronitrile and azobiscyclohexanecarbonitrile. These polymerization initiators may be used alone or in combination of two or more.

The acrylic pressure-sensitive adhesive containing the fluorine-containing (meth) acrylate copolymer preferably contains a crosslinking agent. When the said fluorine-containing (meth) acrylate copolymer has a structural unit derived from the monomer which has the said crosslinkable functional group, a crosslinked structure can be constructed | assembled with a crosslinking agent.
The said crosslinking agent is not specifically limited, For example, an isocyanate type crosslinking agent, an aziridine type crosslinking agent, an epoxy-type crosslinking agent, a metal chelate type crosslinking agent etc. are mentioned. Of these, isocyanate crosslinking agents and epoxy crosslinking agents are preferred.
The blending amount of the crosslinking agent is preferably 0.01 to 10 parts by weight and more preferably 0.1 to 5 parts by weight with respect to 100 parts by weight of the acrylic pressure-sensitive adhesive containing the fluorine-containing (meth) acrylate copolymer. .

The acrylic pressure-sensitive adhesive containing the fluorine-containing (meth) acrylate copolymer may contain a silane coupling agent. Since the acrylic pressure-sensitive adhesive containing the fluorine-containing (meth) acrylate copolymer contains a silane coupling agent, adhesion to the adherend can be improved. be able to.
The silane coupling agent is not particularly limited. For example, vinyltrimethoxysilane, vinyltriethoxysilane, γ-methacryloxypropyltrimethoxysilane, γ-methacryloxypropylmethyldimethoxysilane, γ-glycidoxypropyltrimethoxysilane Γ-glycidoxypropylmethyldimethoxysilane, γ-glycidoxypropylmethyldiethoxysilane, γ-glycidoxypropyltriethoxysilane, 2- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, γ-amino Propyltrimethoxysilane, γ-aminopropyltriethoxysilane, γ-aminopropyltrimethylmethoxysilane, N- (2-aminoethyl) 3-aminopropyltriethoxysilane, N- (2-aminoethyl) 3-aminopropylme Dimethoxysilane, .gamma.-mercaptopropyltrimethoxysilane, .gamma.-mercaptopropyl triethoxy silane, mercaptopropyl butyl trimethoxysilane, .gamma.-mercaptopropyl methyl dimethoxy silane, and the like. Of these, γ-glycidoxypropyltriethoxysilane is preferred.

The content of the silane coupling agent is not particularly limited, but a preferable lower limit with respect to 100 parts by weight of the acrylic pressure-sensitive adhesive containing the fluorine-containing (meth) acrylate copolymer is 0.1 parts by weight, and a preferable upper limit is 5 parts by weight. is there. When the content of the silane coupling agent is 0.1 parts by weight or more, resistance to sebum can be further increased. When the content is 5 parts by weight or less, adhesive residue at the time of re-peeling can be suppressed. The minimum with more preferable content of the said silane coupling agent is 1 weight part, and a more preferable upper limit is 3 weight part.

The acrylic pressure-sensitive adhesive containing the above-mentioned fluorine-containing (meth) acrylate copolymer is optionally added with plasticizer, emulsifier, softener, filler, pigment, dye, etc., rosin resin, terpene resin, etc. May contain other tackifiers and other resins.

The acrylic pressure-sensitive adhesive containing the fluorine-containing (meth) acrylate copolymer preferably has a gel fraction of 5% or more.
It becomes easy to adjust a swelling rate to the said range because the gel fraction of the acrylic adhesive containing the said fluorine-containing (meth) acrylate copolymer is 5% or more. The minimum with more preferable gel fraction of the acrylic adhesive containing the said fluorine-containing (meth) acrylate copolymer is 10%. The upper limit of the gel fraction of the acrylic pressure-sensitive adhesive containing the fluorine-containing (meth) acrylate copolymer is not particularly limited, but the preferable upper limit is 95%, and the more preferable upper limit is 90%.

(2) Acrylic adhesive containing a (meth) acrylate copolymer having a structural unit derived from (meth) acrylate having an alkyl group having 2 or less carbon atoms. The acrylic adhesive is an alkyl having 2 or less carbon atoms. A (meth) acrylate copolymer containing a structural unit derived from a (meth) acrylate having a group (hereinafter simply referred to as a (meth) acrylate copolymer having an alkyl group having 2 or less carbon atoms). It is also preferable. Since the (meth) acrylate copolymer having an alkyl group having 2 or less carbon atoms has high polarity and cohesion, it can prevent the penetration of sebum into the molecular chain. Excellent resistance can be imparted.

Examples of the (meth) acrylate having an alkyl group having 2 or less carbon atoms include methyl (meth) acrylate and ethyl (meth) acrylate. Among these, it is preferable to use ethyl acrylate from the viewpoint that the pressure-sensitive adhesive does not become too hard and can be made into a pressure-sensitive adhesive tape with more excellent adhesive force.

The content of the structural unit derived from the (meth) acrylate having an alkyl group having 2 or less carbon atoms in the (meth) acrylate copolymer having an alkyl group having 2 or less carbon atoms is preferably 80 wt. %, And a preferred upper limit is 97% by weight. When the content of the structural unit derived from the (meth) acrylate having an alkyl group having 2 or less carbon atoms is 80% by weight or more, resistance to sebum can be further increased. When the content of the structural unit derived from the (meth) acrylate having an alkyl group having 2 or less carbon atoms is 97% by weight or less, the pressure-sensitive adhesive does not become too hard, and has a more excellent adhesive force can do. The more preferable lower limit of the content of the structural unit derived from the (meth) acrylate having an alkyl group having 2 or less carbon atoms is 90% by weight, and the more preferable upper limit is 95% by weight.

The (meth) acrylate copolymer having an alkyl group having 2 or less carbon atoms preferably further contains a structural unit derived from a monomer having a crosslinkable functional group.
When the (meth) acrylate copolymer having an alkyl group having 2 or less carbon atoms contains a structural unit derived from a monomer having the crosslinkable functional group, the acrylic adhesive chain is crosslinked when a crosslinking agent is used in combination. Is done. At that time, the gel fraction and the swelling ratio can be adjusted by adjusting the degree of crosslinking.

Examples of the crosslinkable functional group include a hydroxyl group, a carboxyl group, a glycidyl group, an amino group, an amide group, and a nitrile group. Especially, since adjustment of the gel fraction of the said adhesive layer is easy, a hydroxyl group or a carboxyl group is preferable. Examples of the monomer having a hydroxyl group include (meth) acrylic acid esters having a hydroxyl group such as 4-hydroxybutyl (meth) acrylate and 2-hydroxyethyl (meth) acrylate.
As a monomer which has a carboxyl group, (meth) acrylic acid is mentioned, for example.
Examples of the monomer having a glycidyl group include glycidyl (meth) acrylate.
Examples of the monomer having an amide group include hydroxyethyl acrylamide, isopropyl acrylamide, dimethylaminopropyl acrylamide and the like.
Examples of the monomer having a nitrile group include acrylonitrile. These monomers having a crosslinkable functional group may be used alone or in combination.

The content of the structural unit derived from the monomer having a crosslinkable functional group in the (meth) acrylate copolymer having an alkyl group having 2 or less carbon atoms is not particularly limited, but a preferred lower limit is 1% by weight, preferably The upper limit is 5% by weight. When the content of the structural unit derived from the monomer having a crosslinkable functional group is in the above range, the swelling rate and gel fraction can be easily adjusted to the above range.

The (meth) acrylate copolymer having an alkyl group having 2 or less carbon atoms is a propyl acrylate, butyl acrylate, cyclohexyl acrylate, octyl acrylate, nonyl acrylate, isobornyl as long as the effects of the present invention are not impaired. A structural unit derived from acrylate, benzyl acrylate, phenoxyethyl acrylate, vinyl acetate, or the like may be included.

The (meth) acrylate copolymer having an alkyl group having 2 or less carbon atoms preferably has a lower limit of 200,000 and an upper limit of 2 million. When the weight average molecular weight of the (meth) acrylate copolymer having an alkyl group having 2 or less carbon atoms is within the above range, the resulting adhesive tape can be made more excellent in adhesive strength. The more preferable lower limit of the weight average molecular weight of the (meth) acrylate copolymer having an alkyl group having 2 or less carbon atoms is 250,000, and the more preferable upper limit is 1,200,000. The weight average molecular weight can be adjusted depending on the polymerization conditions (for example, the type or amount of the polymerization initiator, the polymerization temperature, the monomer concentration, etc.).

The method for synthesizing the (meth) acrylate copolymer having an alkyl group having 2 or less carbon atoms is not particularly limited, and the same synthesis method as that for the fluorine-containing (meth) acrylate copolymer can be used. Moreover, the same polymerization initiator as the above fluorine-containing (meth) acrylate copolymer can also be used.

The acrylic pressure-sensitive adhesive containing a (meth) acrylate copolymer having an alkyl group having 2 or less carbon atoms preferably contains a crosslinking agent. When the (meth) acrylate copolymer having an alkyl group having 2 or less carbon atoms has a structural unit derived from the monomer having the crosslinkable functional group, a crosslinked structure can be constructed with a crosslinking agent.
The said crosslinking agent is not specifically limited, For example, an isocyanate type crosslinking agent, an aziridine type crosslinking agent, an epoxy-type crosslinking agent, a metal chelate type crosslinking agent etc. are mentioned. Of these, isocyanate crosslinking agents and epoxy crosslinking agents are preferred.
The amount of the crosslinking agent is preferably 0.01 to 10 parts by weight with respect to 100 parts by weight of the acrylic pressure-sensitive adhesive containing the (meth) acrylate copolymer having an alkyl group having 2 or less carbon atoms. 1 to 5 parts by weight is more preferable.

The acrylic pressure-sensitive adhesive containing the (meth) acrylate copolymer having an alkyl group having 2 or less carbon atoms may contain a silane coupling agent. Since the acrylic pressure-sensitive adhesive containing a (meth) acrylate copolymer having an alkyl group having 2 or less carbon atoms contains a silane coupling agent, adhesion to an adherend can be improved. Resistance to sebum of the tape can be further increased.
The said silane coupling agent can use the thing similar to the silane coupling agent described by the acrylic adhesive containing the said fluorine-containing (meth) acrylate copolymer by the same usage-amount.

The acrylic pressure-sensitive adhesive containing a (meth) acrylate copolymer having an alkyl group having 2 or less carbon atoms, if necessary, additives such as plasticizers, emulsifiers, softeners, fillers, pigments, dyes, Other resins such as tackifiers such as rosin resins and terpene resins may be contained.

The acrylic pressure-sensitive adhesive containing a (meth) acrylate copolymer having an alkyl group having 2 or less carbon atoms preferably has a gel fraction of 80% or more.
When the gel fraction of the acrylic pressure-sensitive adhesive containing the (meth) acrylate copolymer having an alkyl group having 2 or less carbon atoms is 80% or more, the swelling rate can be easily adjusted to the above range. A more preferable lower limit of the gel fraction of the acrylic pressure-sensitive adhesive containing a (meth) acrylate copolymer having an alkyl group having 2 or less carbon atoms is 90%. The upper limit of the gel fraction of the acrylic pressure-sensitive adhesive containing the (meth) acrylate copolymer having an alkyl group having 2 or less carbon atoms is not particularly limited, but the preferable upper limit is 98%, and the more preferable upper limit is 95%. .

Although the thickness of the said adhesive layer is not specifically limited, The preferable minimum of the thickness of the said adhesive layer is 5 micrometers, and a preferable upper limit is 50 micrometers. When the thickness of the pressure-sensitive adhesive layer is 5 μm or more, the resulting pressure-sensitive adhesive tape can be made more excellent in adhesiveness. When the thickness of the pressure-sensitive adhesive layer is 50 μm or less, the resulting pressure-sensitive adhesive tape can be made more excellent in workability.

The pressure-sensitive adhesive tape of the present invention may be a support type having a base material or a non-support type having no base material. In the case of the support type, the pressure-sensitive adhesive layer may be formed on one side of the substrate, or the pressure-sensitive adhesive layer may be formed on both sides.

The substrate is not particularly limited. For example, a polyolefin resin film such as a polyethylene film or a polypropylene film, a polyester resin film such as a PET film, an ethylene-vinyl acetate copolymer film, a polyvinyl chloride resin film, or a polyurethane film. Examples include resin film, polyethylene foam sheet, polyolefin foam sheet such as polypropylene foam sheet, and polyurethane foam sheet. Among these substrates, a PET film is preferable. From the viewpoint of impact resistance, a polyolefin foam sheet is preferred.
In addition, as the above-mentioned base material, a black-printed base material for preventing light transmission, a white-printed base material for improving light reflectivity, a metal-deposited base material, and the like can be used.

The manufacturing method of the adhesive tape of this invention is not specifically limited, For example, when the adhesive tape of this invention is a double-sided adhesive tape which has a base material, the following methods are mentioned.
First, a solution of acrylic adhesive a is prepared by adding a solvent to a (meth) acrylate copolymer and, if necessary, a crosslinking agent, and the solution of acrylic adhesive a is applied to the surface of the substrate. The solvent inside is completely removed by drying to form the pressure-sensitive adhesive layer a. Next, the release film is superimposed on the formed pressure-sensitive adhesive layer a so that the release treatment surface faces the pressure-sensitive adhesive layer a.
Next, by preparing a release film different from the release film, applying a solution of acrylic adhesive b on the release treatment surface of the release film, and completely removing the solvent in the solution by drying, A laminated film having the pressure-sensitive adhesive layer b formed on the surface of the release film is produced. The obtained laminated film is laminated on the back surface of the base material on which the pressure-sensitive adhesive layer a is formed, with the pressure-sensitive adhesive layer b facing the back surface of the base material to produce a laminate. And by pressing the said laminated body with a rubber roller etc., the adhesive tape which has an adhesive layer on both surfaces of a base material, and the surface of the adhesive layer was covered with the release film can be obtained.

In addition, two sets of laminated films are produced in the same manner, and a laminated body is produced by superposing these laminated films on both sides of the base material with the adhesive layer of the laminated film facing the base material. By pressing the laminate with a rubber roller or the like, an adhesive tape having an adhesive layer on both surfaces of the substrate and having the surface of the adhesive layer covered with a release film may be obtained.

The use of the pressure-sensitive adhesive tape of the present invention is not particularly limited. However, since it has excellent resistance to sebum, it can be particularly suitably used for fixing parts of electronic devices that are frequently touched by human hands. Specifically, it can be preferably used for fixing a touch panel portion of a portable electronic device such as a smart phone or a tablet terminal, or fixing a display panel portion of an in-vehicle electronic device such as a car navigation system.
An adhesive tape for fixing electronic device parts using the adhesive tape of the present invention is also one aspect of the present invention.

The shape of the pressure-sensitive adhesive tape of the present invention is not particularly limited and may be a rectangle or the like. However, since it is suitable for fixing a touch panel or the like as described above, a frame shape is preferable. Moreover, since the adhesive tape of this invention can maintain high adhesive force even if it is a site | part which a human hand touches frequently, it can be preferably used even if the width | variety of an adhesive tape is narrow.

ADVANTAGE OF THE INVENTION According to this invention, the adhesive tape which is excellent in tolerance to sebum, can maintain adhesive force even if it uses for the part which a human hand touches frequently, and the adhesive for electronic device components consisting of this adhesive tape Tape can be provided.

EXAMPLES The present invention will be described in more detail with reference to examples below, but the present invention is not limited to these examples.

Example 1
(Production of (meth) acrylate copolymer)
Ethyl acetate was added as a polymerization solvent in the reaction vessel, and after bubbling with nitrogen, the reaction vessel was heated while flowing nitrogen and refluxing was started. Subsequently, a polymerization initiator solution in which 0.1 part by weight of azobisisobutyronitrile as a polymerization initiator was diluted 10 times with ethyl acetate was charged into the reaction vessel, and 63.5 parts by weight of butyl acrylate, 2, 2, 23.5 parts by weight of 2-trifluoroethyl acrylate and 3 parts by weight of acrylic acid were added dropwise over 2 hours. After completion of the dropwise addition, a polymerization initiator solution obtained by diluting 0.1 parts by weight of azobisisobutyronitrile 10 times with ethyl acetate as a polymerization initiator was charged again into the reaction vessel, and a polymerization reaction was performed for 4 hours. An acrylate copolymer-containing solution was obtained.

(Manufacture of adhesive tape)
To the obtained (meth) acrylate copolymer-containing solution, 1 part by weight of Tetrad C (manufactured by Mitsubishi Gas Chemical Co., Ltd.) as a crosslinking agent is added to 100 parts by weight of the (meth) acrylate copolymer-containing solution, and the thickness is 75 μm. The release-treated PET film was coated so that the thickness of the pressure-sensitive adhesive layer after drying was 35 μm, and then dried at 110 ° C. for 5 minutes. This pressure-sensitive adhesive layer was transferred to a corona-treated PET film having a thickness of 50 μm serving as a base material and cured at 40 ° C. for 48 hours to obtain a pressure-sensitive adhesive tape.

(Examples 2-11, Comparative Examples 1-4)
A pressure-sensitive adhesive tape was obtained in the same manner as in Example 1 except that the types and amounts of the monomer and the crosslinking agent used were as described in Tables 1 to 3.

(Measurement of gel fraction)
The obtained adhesive tape was cut into a plane rectangular shape of 20 mm × 40 mm to prepare a test piece, and the weight was measured. After immersing the test piece in ethyl acetate at 23 ° C. for 24 hours, the test piece was taken out from ethyl acetate and dried at 110 ° C. for 1 hour. The weight of the test piece after drying was measured, and the gel fraction was calculated using the following formula (1). The results are shown in Tables 1-3.
Gel fraction (% by weight) = 100 × (W ₂ −W ₀ ) / (W ₁ −W ₀ ) (1)
(W ₀ : weight of substrate, W ₁ : weight of test piece before immersion, W ₂ : weight of test piece after immersion and drying)

(Measurement of swelling rate of oleic acid)
The obtained adhesive tape was cut into a plane rectangular shape of 20 mm × 40 mm to prepare a test piece, and the weight was measured. The test piece was immersed in oleic acid for 24 hours under conditions of 60 ° C. and 90% humidity, and then the test piece was taken out of oleic acid, washed with ethanol and then dried at 110 ° C. for 3 hours. The weight of the test piece after drying was measured, and the oleic acid swelling rate of the acrylic pressure-sensitive adhesive was calculated using the following formula (2). The results are shown in Tables 1-3.
Swelling ratio (% by weight) = 100 × (W ₅ −W ₃ ) / (W ₄ −W ₃ ) (2)
(W ₃ : Weight of substrate, W ₄ : Weight of test piece before oleic acid immersion, W ₅ : Weight of test piece after oleic acid immersion and drying)

<Evaluation>
The following evaluation was performed about the adhesive tape obtained by the Example and the comparative example. The results are shown in Tables 1-3.

(180 degree peeling adhesive strength)
The obtained adhesive tape was cut into a strip of 10 mm width to produce a test piece, and one release film was peeled off to expose the adhesive layer. After placing this test piece on a stainless steel plate so that the adhesive layer faces the stainless steel plate, a 2 kg rubber roller is reciprocated once at a speed of 300 mm / min on the test piece, thereby A stainless steel plate was bonded together, and then allowed to stand at 23 ° C. for 24 hours to prepare a test sample. This test sample was heated in an oven at 60 ° C. and 90% humidity for 100 hours and allowed to stand at 23 ° C. for 24 hours. Then, according to JIS Z0237, a tensile test was performed in a 180 ° direction at a peeling rate of 300 mm / min. The 180 ° peeling strength (N / mm) before acid immersion was measured.
Next, the test sample was immersed in an oleic acid bath at 60 ° C. and a humidity of 90% for 100 hours, taken out, washed with water, and allowed to stand for 24 hours. The 180 ° peel strength after the acid immersion was measured.
About the 180 degree peeling adhesive force of the blank and 180 degree peeling adhesive force after oleic acid immersion, the ratio (%) of the residual adhesive force was calculated | required using following formula (3). When the residual adhesive strength ratio is 20% or more or 180 ° peel-off after immersion in oleic acid is ◎, the residual adhesive strength ratio is 5% or more or 180 ° after immersion in oleic acid The case where the peel adhesive strength was 0.04 N / mm or more was evaluated as “◯”, and the ratio of the residual adhesive strength was evaluated as “x” when less than 5%.
Residual adhesive strength ratio (%) = (180 degree peeling adhesive strength after oleic acid immersion / 180 degree peeling adhesive strength before oleic acid immersion) × 100 (3)

(Tackiness)
The pressure-sensitive adhesive surface of the prepared pressure-sensitive adhesive tape was touched by hand, and the tackiness of the pressure-sensitive adhesive tape was evaluated by sensory evaluation. The evaluation was based on the following four grades, with Example 9 as a fine tack and Comparative Example 1 as a high tack standard.
1: Fine tack, 2: Small tack, 3: Medium tack, 4: High tack

ADVANTAGE OF THE INVENTION According to this invention, the adhesive tape which is excellent in tolerance to sebum, can maintain adhesive force even if it uses for the part which a human hand touches frequently, and the adhesive for electronic device components consisting of this adhesive tape Tape can be provided.

Claims (2)

An adhesive tape having an adhesive layer made of an acrylic adhesive on at least one surface, the adhesive layer having a swelling rate of 100% after being immersed in oleic acid for 24 hours at 60 ° C. and a humidity of 90% more state, and are less than 130%,
The acrylic pressure-sensitive adhesive contains a (meth) acrylate copolymer containing 30 to 80% by weight of a structural unit derived from fluorine-containing (meth) acrylate,
The pressure-sensitive adhesive tape, wherein the (meth) acrylate copolymer further contains a structural unit derived from (meth) acrylate having an alkyl group having 2 or less carbon atoms . An adhesive tape for fixing electronic device parts, comprising the adhesive tape according to claim 1 .