JP2019048973A - Adhesive and adhesive tape - Google Patents

Abstract

To provide an adhesive having excellent resistance to sebum and alcohol, and provide an adhesive tape having an adhesive layer composed of the adhesive.SOLUTION: An adhesive contains an acryl copolymer, in which the acryl copolymer contains 30-80 wt.% of a constitutional unit derived from a fluorine-containing (meth) acrylate having a fluorine-containing group with 4 or more carbon atoms and 3 or more fluorine atoms at an ester terminal, in which an adhesive layer composed of the adhesive has a gel fraction of 80 wt.% or less.SELECTED DRAWING: None

Description

The present invention relates to a pressure sensitive adhesive. The present invention also relates to a pressure-sensitive adhesive tape having a pressure-sensitive adhesive layer comprising the pressure-sensitive adhesive.

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).

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

2. Description of the Related Art In recent years, portable electronic devices such as mobile phones, smart phones, wearable terminals and the like that are always worn or kept at hand are widely spread due to downsizing, weight reduction and cost reduction of electronic devices. Since portable electronic devices are frequently used and operated with bare hands using touch panels etc., it is desirable that adhesive tapes have the ability not to deteriorate due to sebum even if they are used for parts that are frequently touched by hands. Be
On the other hand, since portable electronic devices have many opportunities to contact with disinfectants, cleaning liquids, alcoholic beverages, etc. which are used routinely, these disinfectant solutions adhere to the electronic devices on the adhesive tape, and temporarily the adhesive tape Even if it adheres to the above, the performance which does not deteriorate with alcohol contained in disinfectant liquid etc. is also desired. However, in a pressure-sensitive adhesive tape using a conventional pressure-sensitive adhesive, it has not been considered to be compatible with resistance to alcohol while focusing on resistance to sebum.

An object of the present invention is to provide an adhesive excellent in sebum resistance and alcohol resistance. Another object of the present invention is to provide a pressure-sensitive adhesive tape having a pressure-sensitive adhesive layer comprising the pressure-sensitive adhesive.

The present invention is a pressure-sensitive adhesive containing an acrylic copolymer, wherein the acrylic copolymer has a fluorine-containing group having 4 or less carbon atoms and 3 or more fluorine atoms at the ester end. 30% to 80% by weight of the structural unit derived from the above, and the gel fraction of the pressure-sensitive adhesive layer comprising the pressure-sensitive adhesive is 80% by weight or less.
Hereinafter, the present invention will be described in detail.

In the acrylic copolymer used for the conventional adhesive, coexistence with the tolerance to sebum and alcohol tolerance was difficult. The present inventors examined using a fluorine-containing (meth) acrylate as an acrylic copolymer in a pressure-sensitive adhesive containing an acrylic copolymer. As a result, the present inventors particularly use, among various fluorine-containing (meth) acrylates, fluorine-containing (meth) acrylates having a fluorine-containing group having 4 or less carbon atoms and 3 or more fluorine atoms at the ester terminal. And by adjusting the gel fraction of the adhesive layer which consists of an adhesive to a specific range, it discovered that both the tolerance to sebum and alcohol tolerance could be improved. Thus, the present invention has been completed.
In addition, "alcohol" in the present specification means one having a lower alcohol having 4 or less carbon atoms as a single component, or a mixture thereof. As long as a lower alcohol having 4 or less carbon atoms or a mixture thereof is used as the main component (content is 50% by weight or more), water, other solvents such as alcohol having a higher carbon number, additives, etc. may be included.

The pressure-sensitive adhesive of the present invention contains an acrylic copolymer. The acrylic copolymer is derived from a fluorine-containing (meth) acrylate (hereinafter, also simply referred to as "fluorine-containing (meth) acrylate") having a fluorine-containing group having 4 or less carbon atoms and 3 or more fluorine atoms at the ester terminal. 30 to 80% by weight of the constituent units.
The acrylic copolymer contains a structural unit derived from a fluorine-containing (meth) acrylate having a fluorine-containing group at the ester end, whereby the high water and oil repellency of the fluorine itself and the dense packing of the fluorine atom The permeation of oleic acid (main component of sebum) into the molecular chain of the above-mentioned acrylic copolymer is suppressed. Moreover, the cohesive force of an adhesive becomes high compared with the case where carbon number of a fluorine-containing group exceeds 4, when the said acrylic copolymer contains the structural unit derived from the said fluorine-containing (meth) acrylate. As a result, the sebum resistance of the pressure sensitive adhesive is improved.
In addition, since the above-mentioned acrylic copolymer contains a constituent unit derived from the above-mentioned fluorine-containing (meth) acrylate, the cohesion force becomes high as compared with the case where the carbon number of the fluorine-containing group exceeds 4; It also improves the alcohol tolerance of the agent.

The fluorine-containing group is not particularly limited as long as it has 4 or less carbon atoms and 3 or more fluorine atoms, and may be a fluoroalkyl group consisting of only carbon and fluorine, or another element in addition to carbon and fluorine (For example, oxygen) may be included. Examples of the fluorine-containing group containing another element in addition to the above carbon and fluorine include a fluorine-containing group containing a hydroxyl group, a fluorine-containing group containing an ether bond, and the like.

The fluorine-containing (meth) acrylate is not particularly limited, and examples thereof include 2,2,2-trifluoroethyl (meth) acrylate, 1H, 1H, 3H-tetrafluoropropyl (meth) acrylate, 2,2,3,3 , 3-pentafluoropropyl (meth) acrylate, 1H-1- (trifluoromethyl) trifluoroethyl (meth) acrylate, 1H, 1H, 3H-hexafluorobutyl (meth) acrylate, 1,2,2,2- And tetrafluoro-1- (trifluoromethyl) ethyl acrylate. In addition, (meth) acrylate means that it may be an acrylate or a methacrylate. These fluorine-containing (meth) acrylates may be used alone or in combination of two or more. Among them, those having a relatively high solubility parameter (SP value) are preferable. Specifically, a fluorine-containing (meth) acrylate having the solubility parameter (SP value) of 8.3 or more is preferable. As the fluorine-containing (meth) acrylate having the solubility parameter (SP value) of 8.3 or more, 2,2,2-trifluoroethyl (meth) acrylate, 1H, 1H, 3H-tetrafluoropropyl (meth) acrylate And at least one selected from the group consisting of 2,2,3,3,3-pentafluoropropyl (meth) acrylate, and these acrylates are more preferred. Particularly preferred is 2,2,2-trifluoroethyl acrylate because of its particularly high resistance to sebum and alcohol resistance.
The solubility parameter (SP value) can be calculated using the Fedors method (RF Fedors, Polym. Eng. Sci., 14, 147 (1974)). The SP values of the above 2,2,2-trifluoroethyl acrylate, 1H, 1H, 3H-tetrafluoropropyl acrylate and 2,2,3,3,3-pentafluoropropyl acrylate are 8.93, 9 and 9, respectively. 95, 8.57.

In the above-mentioned acrylic copolymer, the lower limit of the content of the constituent unit derived from the above-mentioned fluorine-containing (meth) acrylate is 30% by weight, and the upper limit is 80% by weight. When the content is 30% by weight or more, the permeation of oleic acid into the molecular chain of the acrylic copolymer is suppressed and the cohesion of the adhesive becomes high, and the resistance of the adhesive to sebum and alcohol resistance Improve. When the content is 80% by weight or less, the pressure-sensitive adhesive does not become too hard, and sufficient adhesion can be exhibited. The lower limit of the content is preferably 40% by weight, and the upper limit is preferably 70% by weight, more preferably 45% by weight, and still more preferably 60% by weight.

It is preferable that the said acrylic copolymer further contains the structural unit derived from the alkyl (meth) acrylate which has a C2 or less alkyl group at an ester terminal.
The cohesive strength of the pressure-sensitive adhesive is further enhanced by the acrylic copolymer containing a structural unit derived from an alkyl (meth) acrylate having an alkyl group having 2 or less carbon atoms at the ester end, and the sebum resistance is enhanced. And alcohol tolerance is further improved.

Examples of the alkyl (meth) acrylate having an alkyl group having 2 or less carbon atoms at the ester end include methyl (meth) acrylate and ethyl (meth) acrylate. These alkyl (meth) acrylates having an alkyl group having 2 or less carbon atoms at the ester end may be used alone or in combination of two or more. Among them, ethyl acrylate is preferable because the pressure-sensitive adhesive does not become too hard and can exhibit sufficient adhesion.

Although the content of the structural unit derived from the alkyl (meth) acrylate having an alkyl group having 2 or less carbon atoms at the ester end in the above-mentioned acrylic copolymer is not particularly limited, the preferred lower limit is 15% by weight, and the preferred upper limit is It is 40% by weight. When the content is 15% by weight or more, the cohesion of the adhesive becomes higher, and sebum resistance and alcohol resistance are further improved. When the content is 40% by weight or less, the pressure-sensitive adhesive does not become too hard, and sufficient adhesion can be exhibited. The more preferable lower limit of the content is 20% by weight, and the more preferable upper limit is 30% by weight.

The acrylic copolymer preferably further contains a structural unit derived from a monomer having a crosslinkable functional group.
When the said acrylic copolymer contains the structural unit derived from the monomer which has the said crosslinkable functional group, when using a crosslinking agent together, between the chains of the said acrylic copolymer will be bridge | crosslinked. At that time, the gel fraction of the pressure-sensitive adhesive layer made of a pressure-sensitive adhesive can be adjusted to a specific range as described later by adjusting the degree of crosslinking.

As said crosslinkable functional group, a hydroxyl group, a carboxyl group, 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 adhesive layer which consists of an adhesive 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 the said carboxyl group, (meth) acrylic acid is mentioned, for example. As a monomer which has the said glycidyl group, glycidyl (meth) acrylate is mentioned, for example. Examples of the monomer having an amide group include hydroxyethyl acrylamide, isopropyl acrylamide, dimethylaminopropyl acrylamide and the like. As a monomer which has the said 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 above-mentioned acrylic copolymer is not particularly limited, but the preferable lower limit is 0.05% by weight, the preferable upper limit is 10% by weight, and the more preferable lower limit Is 1% by weight, more preferably 5% by weight. It becomes easy to adjust the gel fraction of the adhesive layer which consists of an adhesive as the said content is in the said range to the specific range which is mentioned later.

The above-mentioned acrylic copolymer is, further, propyl (meth) acrylate, butyl (meth) acrylate, cyclohexyl (meth) acrylate, octyl (meth) acrylate, nonyl (meth) acrylate, isobornyl within a range not inhibiting the effect of the present invention. Constituent units derived from (meth) acrylate, benzyl (meth) acrylate, phenoxyethyl (meth) acrylate, vinyl acetate and the like may be included.

Moreover, when preparing the said acrylic copolymer by an ultraviolet-ray polymerization method, the said acrylic copolymer contains the structural unit derived from polyfunctional monomers, such as divinylbenzene and trimethylol propane tri (meth) acrylate, further. Is preferred.

Although the weight average molecular weight of the said acrylic copolymer is not specifically limited, A preferable minimum is 300,000. If the weight average molecular weight of the acrylic copolymer is 300,000 or more, the amount of displacement when a load in the shear direction is applied to the adhesive is suppressed. In addition, the sebum resistance and alcohol resistance of the adhesive are further improved. A more preferable lower limit to the weight average molecular weight of the above-mentioned acrylic copolymer is 400,000, a still more preferable lower limit is 500,000, and a particularly preferable lower limit is 600,000.
Although the upper limit of the weight average molecular weight of the said acrylic copolymer is not specifically limited, A preferable upper limit is 2 million, A 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 acryl-containing copolymer, the monomer from which the above-mentioned constituent unit is derived 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.

The pressure-sensitive adhesive of the present invention preferably contains a crosslinking agent in addition to the above-mentioned acrylic copolymer.
When the said acrylic copolymer contains the structural unit derived from the monomer which has the said crosslinkable functional group, a crosslinked structure can be comprised between the chains of the said acrylic copolymer by the said crosslinking agent. At that time, the gel fraction of the pressure-sensitive adhesive layer made of a pressure-sensitive adhesive can be adjusted to a specific range as described later by adjusting the degree of crosslinking.

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.
In the pressure-sensitive adhesive of the present invention, the content of the crosslinking agent is not particularly limited, but the preferable lower limit is 0.01 parts by weight and the preferable upper limit is 10 parts by weight with respect to 100 parts by weight of the acrylic copolymer. The upper limit is 0.1 parts by weight, more preferably 5 parts by weight.

The pressure-sensitive adhesive of the present invention preferably further contains a silane coupling agent.
By containing the said silane coupling agent, since the adhesiveness with respect to the to-be-adhered body of an adhesive improves, the tolerance to sebum and alcohol tolerance improve more.

The silane coupling agent is not particularly limited. For example, vinyltrimethoxysilane, vinyltriethoxysilane, 3-methacryloxypropyltrimethoxysilane, 3-methacryloxypropylmethyldimethoxysilane, 3-glycidoxypropyltrimethoxysilane , 3-glycidoxypropylmethyldimethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, 3-glycidoxypropyltriethoxysilane, 2- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, 3-amino Propyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-aminopropyltrimethylmethoxysilane, N- (2-aminoethyl) 3-aminopropyltriethoxysilane, N- (2-aminoethyl) 3-aminopro Methyl dimethoxysilane, 3-mercaptopropyl trimethoxysilane, 3-mercaptopropyl triethoxy silane, mercaptopropyl butyl trimethoxy silane, 3-mercaptopropyl methyl dimethoxy silane, and the like. Among them, 3-glycidoxypropyltrimethoxysilane is preferable.

In the pressure-sensitive adhesive of the present invention, 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 10 parts by weight with respect to 100 parts by weight of the acrylic copolymer. When the content of the silane coupling agent is 0.1 parts by weight or more, the adhesion of the pressure-sensitive adhesive to the adherend is further improved, and resistance to sebum and alcohol resistance are further improved. When the content of the silane coupling agent is 10 parts by weight or less, the adhesive residue when the pressure-sensitive adhesive tape having the pressure-sensitive adhesive layer is peeled can be suppressed, and the reworkability of the pressure-sensitive adhesive tape is improved. 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 5 parts by weight.

The pressure-sensitive adhesive of the present invention optionally contains a plasticizer, an emulsifier, a softener, a filler, an additive such as a pigment and a dye, a tackifier such as a rosin resin and a terpene resin, and other resins. It may be done.

The upper limit of the gel fraction of the pressure-sensitive adhesive layer comprising the pressure-sensitive adhesive of the present invention is 80% by weight.
When the gel fraction is 80% by weight or less, the cohesion of the pressure-sensitive adhesive is in an appropriate range and the adhesion to the adherend is improved, and the resistance to sebum and the alcohol resistance are improved. The upper limit of the gel fraction is preferably 60% by weight, and more preferably 40% by weight.
When the gel fraction exceeds 80% by weight, the alcohol resistance of the pressure-sensitive adhesive is reduced, but at this time, the peeling mode when a force is applied to the adherend after immersion in alcohol changes. That is, if the gel fraction is 80% by weight or less, the cohesion of the pressure-sensitive adhesive is in a proper range, and adhesion to the adherend is maintained even after immersion in alcohol, and a force is applied At the same time, the adhesive layer is usually peeled off by cohesive failure while maintaining the adhesion state at the interface with the adherend. On the other hand, if the gel fraction exceeds 80% by weight, the cohesion of the pressure-sensitive adhesive layer becomes too high, and the adhesion to the adherend after immersion in alcohol decreases, so when force is applied The adhesive layer peels off at the interface with the adherend before cohesive failure occurs.

The lower limit of the gel fraction is not particularly limited, but the preferred lower limit is 5% by weight. When the gel fraction is 5% by weight or more, the pressure-sensitive adhesive layer hardly swells even when the pressure-sensitive adhesive layer formed of the pressure-sensitive adhesive is immersed in oleic acid or alcohol, and sebum resistance and alcohol resistance are further improved. . A more preferable lower limit of the gel fraction is 10% by weight, a still more preferable lower limit is 15% by weight, and a particularly preferable lower limit is 20% by weight.
As used herein, “gel fraction” refers to the weight of the pressure-sensitive adhesive layer after being immersed in ethyl acetate and dried relative to the weight of the pressure-sensitive adhesive layer before being immersed in ethyl acetate as in the following formula (1) Is a value representing the percentage of
Gel fraction (% by weight) = 100 × (W ₂ −W ₀ ) / (W ₁ −W ₀ ) (1)
(W ₀ : Weight of base material, W ₁ : Weight of adhesive tape test piece having adhesive layer consisting of adhesive before immersion in ethyl acetate, W ₂ : Adhesive tape test piece having adhesive layer consisting of adhesive Immersed in ethyl acetate, weight after drying)

The pressure-sensitive adhesive layer comprising the pressure-sensitive adhesive of the present invention has a swelling ratio (also referred to as "oleic acid swelling ratio") of 100% by weight or more and 130% after immersion in oleic acid at 60 ° C and humidity 90% for 24 hours. It is preferable that it is% or less. The upper limit of the oleic acid swelling ratio is more preferably 120% by weight, and still more preferably 115% by weight.
In addition, with "oleic acid swelling ratio" in the present specification, the pressure-sensitive adhesive layer after being soaked in oleic acid with respect to the weight of the pressure-sensitive adhesive layer before being dipped in oleic acid as in the following formula (2) and dried It is a value representing the percentage of weight. When there is elution of the adhesive component into oleic acid, the oleic acid swelling rate is less than 100% by weight.
Oleic acid swelling ratio (% by weight) = 100 × (W ₅ −W ₃ ) / (W ₄ −W ₃ ) (2)
(W ₃ : Weight of base material, W ₄ : Weight of adhesive tape test piece having adhesive layer consisting of adhesive before immersion in oleic acid, W ₅ : Adhesive tape test piece having adhesive layer consisting of adhesive Oleic acid soaking, weight after drying)

The pressure-sensitive adhesive layer comprising the pressure-sensitive adhesive of the present invention has a swelling ratio (“alcohol swelling ratio”) after being immersed in a mixed solution of 80% by weight of isopropanol and 20% by weight of water at 60 ° C. and humidity of 90% for 24 hours. It is preferable that it is 100 weight% or more and 180 weight% or less. The upper limit of the alcohol swelling ratio is more preferably 160% by weight, and still more preferably 140% by weight.
The “alcohol swelling ratio” in the present specification refers to the isopropanomer relative to the weight of the pressure-sensitive adhesive layer prior to immersion in a mixed solution of 80% by weight of isopropanol and 20% by weight of water as in the following formula (3). The ratio of the weight of the pressure-sensitive adhesive layer after being immersed in a mixture of 80% by weight of water and 20% by weight of water and dried is a value represented as a percentage. When there is elution of the adhesive component into the mixture, the alcohol swelling rate is less than 100% by weight.
Alcohol swelling ratio (% by weight) = 100 × (W ₈ −W ₆ ) / (W ₇ −W ₆ ) (3)
(W _6: weight of the substrate, W _7: isopropanol adhesive tape test piece having a pressure-sensitive adhesive layer including the pressure-sensitive adhesive - weight before mixing liquid immersion and Le 80 wt% and 20 wt% water, W _8: adhesive Of a mixture of 80% by weight of isopropanol and 20% by weight of water in a pressure-sensitive adhesive tape test piece having a pressure-sensitive adhesive layer consisting of

The adhesive tape which has an adhesive layer which consists of an adhesive of this invention is also one of this invention.
The thickness of the pressure-sensitive adhesive layer is not particularly limited, but a preferable lower limit is 5 μm and a preferable upper limit is 100 μm. When the thickness of the pressure-sensitive adhesive layer is 5 μm or more, the adhesion of the pressure-sensitive adhesive tape is improved. When the thickness of the pressure-sensitive adhesive layer is 100 μm or less, the processability of the pressure-sensitive adhesive tape is improved.

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 substrate is not particularly limited, and examples thereof include polyolefin resin films such as polyethylene films and polypropylene films, and polyester resin films such as PET films. Furthermore, polyolefin foam sheets such as ethylene-vinyl acetate copolymer film, polyvinyl chloride resin film, polyurethane resin film, polyethylene foam sheet, polypropylene foam sheet, polyurethane foam sheet and the like can be mentioned. Among them, 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 an acrylic copolymer, and if necessary, a crosslinking agent and a silane coupling agent, to prepare a solution of an acrylic adhesive a. The resulting solution of acrylic adhesive a is applied to the surface of a substrate, and the solvent in the solution is completely removed by drying to form an 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.

Although the application of the pressure-sensitive adhesive and the pressure-sensitive adhesive tape of the present invention is not particularly limited, since the resistance to sebum is excellent, the pressure-sensitive adhesive and the pressure-sensitive adhesive tape can be particularly preferably used for fixing parts of electronic devices frequently touched by human hands. In addition, since it is excellent in alcohol resistance, it can be particularly preferably used for fixing parts of electronic devices that are frequently used to touch disinfectants, cleaning liquids, alcoholic beverages and the like that are used routinely. Specifically, the adhesive and the adhesive tape of the present invention are 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. be able to.
The pressure-sensitive adhesive and pressure-sensitive adhesive tape of the present invention can also be preferably used as a transparent pressure-sensitive adhesive for optics and a transparent pressure-sensitive adhesive tape for optics. As such an optical application, for example, bonding of constituent members when manufacturing a polarizing plate or the like, and protecting the surface of an image display device when manufacturing an image display device such as a mobile phone, a smartphone, a tablet terminal And the like, and the like. Furthermore, bonding of a glass plate of a touch panel, a polycarbonate plate or an acrylic plate, and a display panel may be mentioned.

The shape of the pressure-sensitive adhesive tape of the present invention is not particularly limited, and may be rectangular or the like, or may be sheet-like. A frame shape is preferable because it is suitable for fixing the touch panel portion or the display panel portion as described above. The pressure-sensitive adhesive tape of the present invention can be preferably used even if the width of the pressure-sensitive adhesive tape is narrow because it is excellent in sebum resistance and alcohol resistance, and can be particularly preferably used when the width of the pressure-sensitive adhesive tape is 5 mm or less.

According to the present invention, it is possible to provide an adhesive excellent in sebum resistance and alcohol resistance. Further, according to the present invention, it is possible to provide a pressure-sensitive adhesive tape having a pressure-sensitive adhesive layer comprising the pressure-sensitive adhesive.

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

Example 1
(1) Production of Acrylic Copolymer Ethyl acetate as a polymerization solvent was added into a reaction vessel, and after bubbling with nitrogen, the reaction vessel was heated while refluxing 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 with ethyl acetate is introduced into the reaction vessel, and 47 parts by weight of butyl acrylate, 2,2,2- 50 parts by weight of trifluoroethyl acrylate (carbon number of fluorine-containing group = 2, fluorine number = 3 (in the table, 3F)) and 3 parts by weight of acrylic acid were added dropwise over 2 hours. After completion of the dropwise addition, a polymerization initiator solution prepared by diluting 0.1 parts by weight of azobisisobutyronitrile as a polymerization initiator by 10 times with ethyl acetate is again introduced into the reaction vessel, and a polymerization reaction is carried out for 4 hours. A combined solution was obtained.

(2) Measurement of weight average molecular weight of acrylic copolymer A diluted solution obtained by diluting the obtained acrylic copolymer 50 times with tetrahydrofuran (THF) was filtered (material: polytetrafluoroethylene, pore diameter: 0. The sample was filtered through 2 μm to prepare a measurement sample. This measurement sample is supplied to a gel permeation chromatograph (manufactured by Waters, 2690 Separations Model), GPC measurement is performed under the conditions of a sample flow rate of 1 ml / min, and a column temperature of 40 ° C., and polystyrene conversion molecular weight of acrylic copolymer The weight average molecular weight (Mw) was determined. GPC LF-804 (manufactured by Showa Denko KK) was used as a column, and a differential refractometer was used as a detector.

(3) Production of single-sided pressure-sensitive adhesive tape 1 part by weight of a crosslinking agent (isocyanate crosslinking agent, Coronate L-45, manufactured by Tosoh Corp.) to 100 parts by weight of the acrylic copolymer in the obtained acrylic copolymer-containing solution In addition, an adhesive solution was prepared. The pressure-sensitive adhesive solution was applied to a 75 μm-thick release-treated PET film 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 single-sided pressure-sensitive adhesive tape.

(4) Measurement of gel fraction The obtained single-sided pressure-sensitive 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).
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 in ethyl acetate, W ₂ : Weight of test piece after immersion in ethyl acetate, dried)

(Examples 2 to 13, Comparative Examples 1 to 9)
A single-sided pressure-sensitive adhesive tape was obtained in the same manner as in Example 1, except that the composition of the acrylic copolymer, the type or amount of the crosslinking agent, and the amount of the silane coupling agent were changed as shown in Table 1 or 2. The details of the materials shown in Table 1 or 2 are as follows.

· Crosslinking agent (epoxy based crosslinking agent, E-5C, manufactured by Soken Chemical Co., Ltd.)
・ Silane coupling agent (KBM-403, Shin-Etsu Chemical Co., Ltd.)

<Evaluation>
The following evaluation was performed about the single-sided adhesive tape obtained by the Example and the comparative example. The results are shown in Table 1 or 2.

(1) Measurement of 180 ° Peeling Adhesion The obtained single-sided pressure-sensitive adhesive tape was cut into 10 mm wide strips to prepare test pieces, and the release film was peeled off to expose the pressure-sensitive adhesive layer. After placing this test piece on a stainless steel plate with the adhesive layer facing the stainless steel plate, the test piece and the stainless steel are reciprocated by moving a 2 kg rubber roller once at a speed of 300 mm / min on the test piece. The plates were attached to each other and then allowed to stand at 23 ° C. for 24 hours to prepare test samples.

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 immersion was measured. In addition, it was set to 0 when the 180 ° peel strength was less than the measurement limit value of the device.

The test sample was immersed in a bath of oleic acid or isopropanol (IPA: more specifically, a mixture of 80% by weight of isopropanol and 20% by weight of water) at 60 ° C. and 90% humidity for 100 hours and taken out. After washing with water, it was allowed to stand for 24 hours. Thereafter, according to JIS Z0237, a tensile test in a 180 ° direction was performed at a peeling speed of 300 mm / min, and 180 ° peel adhesion (N / mm) after immersion in oleic acid or IPA was measured.
(Judgment criteria)
When the 180 ° peel adhesive strength (N / mm) value is less than 0.2 N / mm, ×, when 0.2 N / mm or more and 0.4 N / mm or less, Δ, 0.4 N / mm The case where it was greater than or equal to mm and less than 0.6 N / mm was ○, and the case where it was 0.6 N / mm or more was を. Tables 1 and 2 also show the peeling mode of the pressure-sensitive adhesive layer. The case of cohesive failure is referred to as “flocculation” and the case of interfacial peeling is referred to as “interface”.

According to the present invention, it is possible to provide an adhesive excellent in sebum resistance and alcohol resistance. Further, according to the present invention, it is possible to provide a pressure-sensitive adhesive tape having a pressure-sensitive adhesive layer comprising the pressure-sensitive adhesive.

Claims (6)

It is an adhesive containing an acrylic copolymer,
The acrylic copolymer contains 30 to 80% by weight of a structural unit derived from a fluorine-containing (meth) acrylate having at its ester terminal a fluorine-containing group having 4 or less carbon atoms and 3 or more fluorine atoms.
The gel fraction of the pressure-sensitive adhesive layer comprising the pressure-sensitive adhesive is 80% by weight or less. A fluorine-containing (meth) acrylate having a fluorine-containing group having a carbon number of 4 or less and a fluorine number of 3 or more at the ester terminal is 2,2,2-trifluoroethyl (meth) acrylate, 1H, 1H, 3H-tetrafluoro The pressure-sensitive adhesive according to claim 1, which is at least one selected from the group consisting of propyl (meth) acrylate and 2,2,3,3,3-pentafluoropropyl (meth) acrylate. 3. The pressure-sensitive adhesive according to claim 1, wherein the acrylic copolymer further contains a structural unit derived from an alkyl (meth) acrylate having an alkyl group having 2 or less carbon atoms at an ester end. The pressure-sensitive adhesive according to claim 1, 2 or 3, further comprising a silane coupling agent. A pressure-sensitive adhesive tape comprising a pressure-sensitive adhesive layer comprising the pressure-sensitive adhesive according to claim 1, 2, 3 or 4. The pressure-sensitive adhesive tape according to claim 5, which is used to fix parts of an electronic device.