JP2019048904A - Adhesive tape and adhesive tape for fixing electronic device component - Google Patents

Abstract

To provide an adhesive tape excellent in resistance to sebum and capable of maintaining adhesive force even when used in a part to which human hands touch frequently, and an adhesive tape for fixing an electronic device component consisting of the adhesive tape.SOLUTION: There is provided an adhesive tape having an adhesive layer consisting of an acrylic adhesive on at least one surface, in which the adhesive layer has swelling rate after impregnating into oleic acid under a condition of 60°C and humidity of 90% for 24 hr. of 100% to 130%.SELECTED DRAWING: None

Description

The present invention relates to a pressure-sensitive adhesive tape excellent in resistance to sebum and capable of maintaining adhesion even when used for a part which is frequently touched by human hands, and a pressure-sensitive adhesive tape for fixing electronic device parts comprising the pressure-sensitive adhesive tape. .

2. Description of the Related Art Conventionally, adhesive tapes have been widely used in 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. In addition to high adhesiveness, the adhesive tape used for fixing such electronic device parts is required to have functions such as heat resistance, thermal conductivity, and impact resistance according to the environment of the part used (for example, a patent) Documents 1 to 3).

2. Description of the Related Art In recent years, with the downsizing, weight reduction, and cost reduction of electronic devices, electronic devices that are always worn or kept at hand, such as mobile phones, smart phones, and wearable terminals, are widely used. Since such portable electronic devices are frequently used and operated with bare hands using a touch panel or the like, when an adhesive tape is used for the part that the user touches frequently, the adhesive tape is made of sebum. There is a problem of deterioration and peeling off.

Unexamined-Japanese-Patent No. 2015-052050 JP, 2015-021067, A JP, 2015-120876, A

The present invention provides a pressure-sensitive adhesive tape excellent in resistance to sebum and capable of maintaining adhesion even when used for a part which human hands frequently touch, and a pressure-sensitive adhesive tape for fixing electronic device parts comprising the pressure-sensitive adhesive tape. Intended to be provided.

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

As a result of intensive investigations against the problem of peeling of the adhesive due to the sebum, the present inventors are exposed to sebum by using an acrylic adhesive whose swelling ratio after immersion in oleic acid is within a specific range. It has been found that the adhesive strength can be maintained even in the case where the present invention is achieved.

The pressure-sensitive adhesive tape of the present invention has a pressure-sensitive adhesive layer composed of an acrylic pressure-sensitive adhesive on at least one surface, and the pressure-sensitive adhesive layer swells after being immersed in oleic acid for 24 hours under conditions of 60 ° C and 90% humidity. Is 100% to 130%.
When the oleic acid swelling ratio of the pressure-sensitive adhesive layer is in the above-mentioned range, the pressure-sensitive adhesive tape of the present invention exhibits high resistance to deterioration by oleic acid which is the main component of sebum, It is possible to prevent the peeling of the pressure-sensitive adhesive tape even when it is used. The upper limit of the oleic acid swelling ratio is preferably 120%, more preferably 110%.
In the present specification, “swelling ratio” is a value representing the percentage of the weight of the pressure-sensitive adhesive after immersion in oleic acid with respect to the weight of the pressure-sensitive adhesive before immersion in oleic acid as represented by the following formula. It is.
Swelling ratio (% by weight) = (weight of adhesive after immersion in oleic acid / weight of adhesive before immersion in oleic acid) × 100

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

(1) Acrylic adhesive containing a (meth) acrylate copolymer having a constituent unit derived from fluorine-containing (meth) acrylate The above-mentioned acrylic adhesive has a constituent unit derived from fluorine-containing (meth) acrylate It is preferable to contain an 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 that tight packing of fluorine atoms makes it difficult for sebum to penetrate into the molecular chain. Adhesive tape can provide high resistance to sebum. 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, for example, 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 1,1H, 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 them, it is preferable to use 2,2,2-trifluoroethyl acrylate because the resistance to sebum is particularly high.

The content of the constituent unit derived from the above-mentioned fluorine-containing (meth) acrylate in the above-mentioned fluorine-containing (meth) acrylate copolymer is such that the preferable lower limit is 30% by weight and the preferable upper limit is 80% by weight. It becomes easy to adjust an 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 above-mentioned 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 having more excellent adhesion can be obtained. The more preferable lower limit of the content of the constituent unit derived from the above-mentioned fluorine-containing (meth) acrylate is 40% by weight, and the more preferable upper limit is 60% by weight.

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

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 a pressure-sensitive adhesive tape having more excellent adhesion can be obtained.

The content of the structural unit derived from a (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 preferable lower limit is 15% by weight, a preferable upper limit Is 40% by weight. When the content of the (meth) acrylate having an alkyl group having 2 or less carbon atoms is in the above range, the resistance to sebum of the obtained adhesive tape can be further enhanced. The lower limit of the content of the structural unit derived from a (meth) acrylate having an alkyl group having 2 or less carbon atoms in the fluorine-containing (meth) acrylate copolymer is more preferably 20% by weight, more preferably 30% by weight %.

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 constituent unit derived from the monomer having the crosslinkable functional group, the fluorine-containing (meth) acrylate copolymer is crosslinked when it is used in combination with a crosslinking agent. . At this time, the gel fraction and the swelling ratio can be adjusted by adjusting the degree of crosslinking.

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

The content of the constituent unit derived from the monomer having the crosslinkable functional group in the fluorine-containing (meth) acrylate copolymer is not particularly limited, but a preferable lower limit is 1% by weight and a preferable upper limit is 5% by weight. When the content of the structural unit derived from the monomer having the crosslinkable functional group is in the above range, the swelling ratio and the gel fraction can be easily adjusted to the above range.

The above-mentioned fluorine-containing (meth) acrylate copolymer is further in the range which does not inhibit the effect of the present invention, and further, propyl acrylate, butyl acrylate, cyclohexyl acrylate, octyl acrylate, nonyl acrylate, isobornyl acrylate, benzyl acrylate, phenoxyethyl acrylate And vinyl acetate may be included.

The lower limit of the weight average molecular weight of the fluorine-containing (meth) acrylate copolymer is preferably 500,000 and the upper limit is 2,000,000. By the weight average molecular weight of the said fluorine-containing (meth) acrylate copolymer being the said range, the adhesive tape obtained can be made more excellent in adhesiveness. The more preferable lower limit of the weight average molecular weight of the fluorine-containing (meth) acrylate copolymer is 600,000, and the more preferable upper limit is 1.2 million. In addition, a weight average molecular weight can be adjusted with superposition | polymerization conditions (For example, the kind or quantity of a polymerization initiator, superposition | polymerization temperature, monomer concentration etc.).

In order to synthesize the above-mentioned fluorine-containing (meth) acrylate copolymer, an acryl monomer which is the origin of the above-mentioned constituent unit may be radically reacted in the presence of a polymerization initiator. The polymerization method is not particularly limited, and conventionally known methods can be used. For example, solution polymerization (boiling point polymerization or constant temperature polymerization), emulsion polymerization, suspension polymerization, bulk polymerization and the like can be mentioned. Among them, solution polymerization is preferable because the 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, and 2,5. -Dimethyl-2,5-bis (2-ethylhexanoylperoxy) hexane, t-hexylperoxy-2-ethylhexanoate, t-butylperoxy-2-ethylhexanoate, t-butylperoxy Isobutyrate, t-butylperoxy-3,5,5-trimethylhexanoate, t-butylperoxy laurate and the like can be mentioned. Examples of the azo compound include azobisisobutyronitrile, azobiscyclohexanecarbonitrile and the like. These polymerization initiators may be used alone or in combination of two or more.

It is preferable that the acrylic adhesive containing the said fluorine-containing (meth) acrylate copolymer 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 comprised by 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. Among these, isocyanate crosslinking agents and epoxy crosslinking agents are preferable.
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 adhesive containing the fluorine-containing (meth) acrylate copolymer may contain a silane coupling agent. The adhesion to an adherend can be improved by the acrylic pressure-sensitive adhesive containing the above-mentioned fluorine-containing (meth) acrylate copolymer containing a silane coupling agent, thereby further enhancing the sebum resistance of the pressure-sensitive adhesive tape. 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-aminopropyl ester Dimethoxysilane, .gamma.-mercaptopropyltrimethoxysilane, .gamma.-mercaptopropyl triethoxy silane, mercaptopropyl butyl trimethoxysilane, .gamma.-mercaptopropyl methyl dimethoxy silane, and the like. Among them, γ-glycidoxypropyltriethoxysilane is preferable.

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

The acrylic adhesive containing the above-mentioned fluorine-containing (meth) acrylate copolymer is, if necessary, a plasticizer, an emulsifier, a softener, a filler, an additive such as a pigment, a dye, a rosin resin, a terpene resin, etc. And other resins may be contained.

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 more preferable lower limit of the gel fraction of the acrylic adhesive containing the above-mentioned fluorine-containing (meth) acrylate copolymer is 10%. Although the upper limit of the gel fraction of the acrylic adhesive containing the said fluorine-containing (meth) acrylate copolymer is not specifically limited, A preferable upper limit is 95%, A 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 described above is an alkyl having 2 or less carbon atoms (Meth) acrylate copolymer containing a structural unit derived from (meth) acrylate having a group (hereinafter, referred to simply as (meth) acrylate copolymer having an alkyl group having 2 or less carbon atoms) Is also preferred. The (meth) acrylate copolymer having an alkyl group having 2 or less carbon atoms has high polarity and high cohesion, so that sebum can be prevented from entering 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 them, it is preferable to use ethyl acrylate from the viewpoint that the pressure-sensitive adhesive does not become too hard and can be a pressure-sensitive adhesive tape having more excellent adhesion.

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 has a preferable lower limit of 80 weight %, A preferred upper limit is 97% by weight. When the content of the structural unit derived from a (meth) acrylate having an alkyl group having 2 or less carbon atoms is 80% by weight or more, the resistance to sebum can be further enhanced. Since the content of the structural unit derived from a (meth) acrylate having an alkyl group having 2 or less carbon atoms is 97% by weight or less, a pressure-sensitive adhesive does not become too hard, and a pressure-sensitive adhesive tape having more excellent adhesion 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 pressure-sensitive adhesive chains are crosslinked when used in combination with a crosslinking agent. Be done. At this time, the gel fraction and the swelling ratio can be adjusted by adjusting the degree of crosslinking.

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

The content of the structural unit derived from the monomer having the crosslinkable functional group in the (meth) acrylate copolymer having an alkyl group having 2 or less carbon atoms is not particularly limited, but a preferable 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 the crosslinkable functional group is in the above range, the swelling ratio and the gel fraction can be easily adjusted to the above range.

The (meth) acrylate copolymer having an alkyl group having 2 or less carbon atoms does not inhibit the effect of the present invention, and further, propyl acrylate, butyl acrylate, cyclohexyl acrylate, octyl acrylate, nonyl acrylate, isobornyl Constituent units derived from acrylate, benzyl acrylate, phenoxyethyl acrylate, vinyl acetate and the like may be included.

The lower limit of the weight average molecular weight of the (meth) acrylate copolymer having an alkyl group having 2 or less carbon atoms is preferably 200,000 and the upper limit is 2,000,000. When the weight average molecular weight of the (meth) acrylate copolymer having an alkyl group having 2 or less carbon atoms is in the above range, the obtained pressure-sensitive adhesive tape can be made more excellent in adhesion. 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 1.2 million. In addition, a weight average molecular weight can be adjusted with superposition | polymerization conditions (For example, the kind or quantity of a polymerization initiator, superposition | polymerization temperature, monomer concentration etc.).

The method of 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 the fluorine-containing (meth) acrylate copolymer can be used. Further, as the polymerization initiator, the same one as the above-mentioned fluorine-containing (meth) acrylate copolymer can be used.

It is preferable that the acrylic adhesive containing the (meth) acrylate copolymer which has the said C2 or less alkyl group which has an alkyl group 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 a monomer having the crosslinkable functional group, a crosslinking structure can be constructed by 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. Among these, isocyanate crosslinking agents and epoxy crosslinking agents are preferable.
The compounding 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 preferred.

The acrylic 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 adhesive containing the (meth) acrylate copolymer having an alkyl group having 2 or less carbon atoms contains a silane coupling agent, the adhesion to the adherend can be improved, and therefore adhesion The sebum resistance of the tape can be further enhanced.
The same silane coupling agent as the silane coupling agent described in the acrylic pressure-sensitive adhesive containing the above-mentioned fluorine-containing (meth) acrylate copolymer can be used as the above-mentioned silane coupling agent in the same use amount.

The acrylic pressure-sensitive adhesive containing a (meth) acrylate copolymer having an alkyl group having 2 or less carbon atoms is an additive such as a plasticizer, an emulsifier, a softener, a filler, a pigment, a dye, if necessary It may contain other resins such as tackifiers such as rosin resins and terpene resins, and the like.

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.
It becomes easy to adjust a swelling rate to the said range because the gel fraction of the acrylic adhesive containing the (meth) acrylate copolymer which has the said C2 or less alkyl group is 80% or more. The more preferable lower limit of the gel fraction of the acrylic 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 adhesive containing the (meth) acrylate copolymer having an alkyl group having 2 or less carbon atoms is not particularly limited, but the upper limit is preferably 98%, more preferably 95%. .

The thickness of the pressure-sensitive adhesive layer is not particularly limited, but the preferable lower limit of the thickness of the pressure-sensitive adhesive layer is 5 μm, and the preferable upper limit is 50 μm. By the thickness of the said adhesive layer being 5 micrometers or more, the adhesive tape obtained can be made more excellent in adhesiveness. When the thickness of the pressure-sensitive adhesive layer is 50 μm or less, the obtained pressure-sensitive adhesive tape can be made more excellent in processability.

The pressure-sensitive adhesive tape of the present invention may be a support type having a substrate or may be a non-support type having no substrate. 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 said base material is not specifically limited, For example, Polyolefin resin films, such as a polyethylene film and a polypropylene film, Polyester resin films, such as a PET film, An ethylene-vinyl acetate copolymer film, a polyvinyl chloride resin film, Polyurethane type Examples thereof include polyolefin foam sheets such as resin films, polyethylene foam sheets, and polypropylene foam sheets, polyurethane foam sheets, and the like. Among these substrates, PET film is preferable. Also, from the viewpoint of impact resistance, a polyolefin foam sheet is preferred.
In addition, as the above-mentioned substrate, a substrate printed black for preventing light transmission, a substrate printed white for improving light reflectivity, a substrate vapor-deposited with metal, etc. can be used.

The method for producing the pressure-sensitive adhesive tape of the present invention is not particularly limited. For example, when the pressure-sensitive adhesive tape of the present invention is a double-sided pressure-sensitive adhesive tape having a substrate, the following methods may be mentioned.
First, a solvent is added to a (meth) acrylate copolymer, a cross-linking agent if necessary, etc. to prepare a solution of an acrylic adhesive a, and the solution of the acrylic adhesive a is applied to the surface of a substrate, The solvent is completely removed by drying to form a pressure-sensitive adhesive layer a. Next, a release film is superimposed on the formed pressure-sensitive adhesive layer a with the release-treated surface of the release film facing the pressure-sensitive adhesive layer a.
Next, a release film different from the above release film is prepared, a solution of an acrylic adhesive b is applied to the release-treated surface of the release film, and the solvent in the solution is completely removed by drying. The laminated film in which the adhesive layer b was formed on the surface of the release film is produced. The resulting laminated film is superimposed on the back surface of the substrate on which the pressure-sensitive adhesive layer a is formed, in a state where the pressure-sensitive adhesive layer b faces the back surface of the substrate, to prepare a laminate. Then, by pressing the above laminate with a rubber roller or the like, it is possible to obtain a pressure-sensitive adhesive tape having a pressure-sensitive adhesive layer on both sides of the substrate and having the surface of the pressure-sensitive adhesive layer covered with a release film.

In addition, two sets of laminated films are prepared in the same manner, and these laminated films are superimposed on each of the two sides of the substrate in such a state that the pressure-sensitive adhesive layer of the laminated film is opposed to the substrate to prepare a laminate. By pressing the laminate with a rubber roller or the like, it is possible to obtain a pressure-sensitive adhesive tape having a pressure-sensitive adhesive layer on both sides of the substrate and having the surface of the pressure-sensitive adhesive layer covered with a release film.

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

The shape of the pressure-sensitive adhesive tape of the present invention is not particularly limited, and may be rectangular 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, even if the width of an adhesive tape is narrow, it can be used preferably.

According to the present invention, a pressure-sensitive adhesive tape which is excellent in resistance to sebum and can maintain adhesion even when used for a part which human hands frequently touch, and an adhesion for fixing electronic device parts comprising the pressure-sensitive adhesive tape Tape can be provided.

EXAMPLES The present invention will be described in more detail by way of examples, but the present invention is not limited to these examples.

Example 1
(Production of (meth) acrylate copolymer)
Ethyl acetate as a polymerization solvent was added to the reaction vessel, and after bubbling with nitrogen, the reaction vessel was heated while refluxing with nitrogen to start refluxing. Subsequently, a polymerization initiator solution prepared by diluting 0.1 parts by weight of azobisisobutyronitrile as a polymerization initiator with 10 times of ethyl acetate is introduced into the reaction vessel, and 63.5 parts by weight of butyl acrylate, 2,2,2, 33.5 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 in which 0.1 part by weight of azobisisobutyronitrile is diluted 10-fold with ethyl acetate as a polymerization initiator is again introduced into the reaction vessel, and the polymerization reaction is carried out for 4 hours. An acrylate copolymer-containing solution was obtained.

(Production 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 with respect to 100 parts by weight of the (meth) acrylate copolymer-containing solution to have a thickness of 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. The pressure-sensitive adhesive layer was transferred onto a corona-treated PET film having a thickness of 50 μm as a base material, and cured at 40 ° C. for 48 hours to obtain a pressure-sensitive adhesive tape.

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

(Measurement of gel fraction)
The obtained adhesive tape was cut into a 20 mm × 40 mm flat rectangular shape 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 removed 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 to 3.
Gel fraction (% by weight) = 100 × (W ₂ −W ₀ ) / (W ₁ −W ₀ ) (1)
(W ₀ : Weight of base material, W ₁ : Weight of test piece before immersion, W ₂ : Weight of test piece after immersion, drying)

(Measurement of oleic acid swelling rate)
The obtained adhesive tape was cut into a 20 mm × 40 mm flat rectangular shape to prepare a test piece, and the weight was measured. After immersing the test piece in oleic acid under conditions of 60 ° C. and humidity 90% for 24 hours, the test piece was removed from the oleic acid, washed with ethanol and 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 adhesive was calculated using the following formula (2). The results are shown in Tables 1 to 3.
Swelling ratio (% by weight) = 100 × (W ₅ −W ₃ ) / (W ₄ −W ₃ ) (2)
(W ₃ : Weight of base material, W ₄ : Weight of test piece before immersion in oleic acid, W ₅ : Weight of test piece after immersion in oleic acid)

<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 to 3.

(180 ° peel strength)
The obtained pressure-sensitive adhesive tape was cut into strips of 10 mm width to prepare test pieces, and one of the release films was peeled and removed to expose the pressure-sensitive adhesive layer. After placing this test piece on a stainless steel plate so that the adhesive layer faces the stainless steel plate, the test piece and the test piece are reciprocated by moving a 2 kg rubber roller once at a speed of 300 mm / min. A test sample was prepared by bonding together with a stainless steel plate and then standing at 23 ° C. for 24 hours. The test sample is heated in an oven at 60 ° C. and 90% humidity for 100 hours and allowed to stand at 23 ° C. for 24 hours, and then a tensile test in the 180 ° direction is performed at a peeling speed of 300 mm / min. The 180 ° peel adhesion (N / mm) before acid immersion was measured.
Next, the above test sample is immersed in an oleic acid bath at 60 ° C. and 90% humidity for 100 hours, taken out, washed with water, and allowed to stand for 24 hours to conduct the above-mentioned tensile test, and olein The 180 ° peel adhesion after acid immersion was measured.
The ratio (%) of the residual adhesion was determined using the following equation (3) for the 180 ° peel adhesion of the blank and the 180 ° peel adhesion after immersion in oleic acid.場合 When residual adhesion ratio is 20% or more or 180 ° peel adhesion after oleic acid immersion is ◎, residual adhesion ratio is 5% or more or 180 ° after oleic acid immersion The case where peeling adhesive strength is 0.04 N / mm or more was evaluated as ○, and the ratio of residual adhesive strength was evaluated as x less than 5%.
Ratio of residual adhesion (%) = (180 ° peel adhesion after immersion in oleic acid / 180 ° peel adhesion before immersion in oleic acid) × 100 (3)

(Tackiness)
The adhesive side of the produced adhesive tape was touched with a hand, and the tackiness of the adhesive tape was evaluated by sensory evaluation. Evaluation made Example 9 the fine tack, and made Comparative example 1 the reference | standard of high tack, and set it as the following 4-step evaluation.
1: fine tack, 2: small tack, 3: medium tack, 4: high tack

According to the present invention, a pressure-sensitive adhesive tape which is excellent in resistance to sebum and can maintain adhesion even when used for a part which human hands frequently touch, and an adhesion for fixing electronic device parts comprising the pressure-sensitive adhesive tape Tape can be provided.

Claims (5)

A pressure-sensitive adhesive tape having a pressure-sensitive adhesive layer comprising an acrylic pressure-sensitive adhesive on at least one surface, wherein the pressure-sensitive adhesive layer has a swelling ratio of 100% after immersion in oleic acid at 60 ° C. and 90% humidity for 24 hours The pressure-sensitive adhesive tape as described above is 130% or less. The pressure-sensitive adhesive tape according to claim 1, wherein the acrylic pressure-sensitive adhesive contains a (meth) acrylate copolymer containing 30% by weight to 80% by weight of a structural unit derived from fluorine-containing (meth) acrylate. The pressure-sensitive adhesive tape according to claim 2, wherein the (meth) acrylate copolymer further contains a structural unit derived from (meth) acrylate having an alkyl group having 2 or less carbon atoms. The acrylic adhesive contains a (meth) acrylate copolymer containing 80% by weight to 97% by weight of a structural unit derived from a (meth) acrylate having an alkyl group having 2 or less carbon atoms, and the gel fraction is 80 The pressure-sensitive adhesive tape according to claim 1, characterized in that it is% or more. It consists of an adhesive tape of Claim 1, 2, 3 or 4, The adhesive tape for electronic device component fixation characterized by the above-mentioned.