WO2016158413A1

WO2016158413A1 - Temperature-sensitive adhesive composition

Info

Publication number: WO2016158413A1
Application number: PCT/JP2016/058297
Authority: WO
Inventors: 智博西尾; 浩祐丸谷
Original assignee: ニッタ株式会社
Priority date: 2015-04-01
Filing date: 2016-03-16
Publication date: 2016-10-06
Also published as: JP6898226B2; KR102452985B1; TW201704420A; JPWO2016158413A1; KR20170134972A; CN107406737A; CN107406737B; TWI589658B

Abstract

This temperature-sensitive adhesive composition contains at least a side chain crystalline (meth)acrylic polymer, a (meth)acrylic monomer, a polyfunctional (meth)acrylate, and a photo-radical initiator. The temperature-sensitive adhesive composition exhibits ultraviolet radiation curing properties and is a liquid. Among the side chain crystalline (meth)acrylic polymer, the (meth)acrylic monomer, the polyfunctional (meth)acrylate, and the photo-radical initiator, the overall content of the side chain crystalline (meth)acrylic polymer and the (meth)acrylic monomer should be the highest.

Description

Temperature-sensitive adhesive composition

The present invention relates to a temperature-sensitive adhesive composition.

A temperature-sensitive adhesive is known as an adhesive capable of reversibly controlling the adhesive force by heat (for example, see Patent Document 1). The conventional temperature-sensitive adhesive as described in Patent Document 1 is usually a polymer solution obtained by polymerizing monomers in an organic solvent, and this polymer solution is applied to a film-like substrate and dried. It is processed into adhesive tape.

By the way, since the adhesive tape is used in various applications, for example, an adhesive tape having a thick adhesive layer so as to follow the step of the adherend may be required.

However, the conventional temperature-sensitive pressure-sensitive adhesive has a problem that when the thickness of the coating film is increased to increase the thickness of the pressure-sensitive adhesive layer, bubbles are generated in the film due to volatilization of the organic solvent when dried. . Moreover, since the conventional temperature sensitive adhesive uses the organic solvent, there also existed a problem that environmental impact was large.

On the other hand, as a pressure-sensitive adhesive not containing an organic solvent, a liquid pressure-sensitive adhesive composition comprising an acrylic monomer, a viscosity adjusting polymer, and a photo radical initiator is known.

However, this pressure-sensitive adhesive composition has a problem in that sufficient pressure-sensitive adhesive properties cannot be obtained, although a thick pressure-sensitive adhesive layer can be formed by coating and UV curing.

JP-A-9-251923

An object of the present invention is to provide a temperature-sensitive adhesive composition capable of forming a thick adhesive layer having excellent adhesive properties.

The temperature-sensitive adhesive composition of the present invention contains at least a side-chain crystalline (meth) acrylic polymer, a (meth) acrylic monomer, a polyfunctional (meth) acrylate, and a photo radical initiator, and has ultraviolet curability. And it is liquid.

According to the present invention, there is an effect that a thick adhesive layer having excellent adhesive properties can be formed.

<Temperature sensitive adhesive composition>
Hereinafter, a temperature-sensitive adhesive composition according to an embodiment of the present invention (hereinafter sometimes referred to as “adhesive composition”) will be described in detail.

The pressure-sensitive adhesive composition of the present embodiment contains at least a side chain crystalline (meth) acrylic polymer, a (meth) acrylic monomer, a polyfunctional (meth) acrylate, and a photoradical initiator, and ultraviolet (Ultra Violet: It may be referred to as “UV”.) It is UV curable by being irradiated and is liquid.

[Side-chain crystalline (meth) acrylic polymer]
The side chain crystalline (meth) acrylic polymer of this embodiment is a polymer obtained by polymerizing a (meth) acrylate having a linear alkyl group having at least 16 carbon atoms.

In the (meth) acrylate having a linear alkyl group having 16 or more carbon atoms, the linear alkyl group having 16 or more carbon atoms functions as a side chain crystalline part in the side chain crystalline (meth) acrylic polymer. That is, the side chain crystalline (meth) acrylic polymer is a comb-shaped polymer having a linear alkyl group having 16 or more carbon atoms in the side chain, and the side chain is aligned in an ordered arrangement by intermolecular force or the like. To crystallize.

And the side chain crystalline (meth) acrylic polymer of this embodiment has a melting point in connection with the crystallization described above. The melting point is a temperature at which a specific portion of the polymer that is initially aligned in an ordered arrangement becomes disordered by an equilibrium process, and is measured by a differential thermal scanning calorimeter (DSC) at 10 ° C./min. It means the value obtained in this way.

The side-chain crystalline (meth) acrylic polymer of the present embodiment has a temperature sensitivity that crystallizes at a temperature lower than the above-described melting point and undergoes phase transition at a temperature higher than the melting point to exhibit fluidity. Therefore, the pressure-sensitive adhesive composition of this embodiment containing a side-chain crystalline (meth) acrylic polymer adheres when the side-chain crystalline (meth) acrylic polymer flows at a temperature equal to or higher than the melting point after UV curing. When the side chain crystalline (meth) acrylic polymer is crystallized at a temperature lower than the melting point, the adhesive strength is lowered. If the pressure-sensitive adhesive composition is heated again to a temperature equal to or higher than the melting point, the side chain crystalline (meth) acrylic polymer exhibits fluidity, and thus the adhesive strength is recovered. Therefore, it can be used repeatedly.

Examples of the (meth) acrylate having a linear alkyl group having 16 or more carbon atoms constituting the side chain crystalline (meth) acrylic polymer include cetyl (meth) acrylate, stearyl (meth) acrylate, and eicosyl (meth) acrylate. And (meth) acrylates having a linear alkyl group having 16 to 22 carbon atoms, such as behenyl (meth) acrylate, and these may be used alone or in combination of two or more. (Meth) acrylate means acrylate or methacrylate. This is the same for other (meth) acrylates.

The side chain crystalline (meth) acrylic polymer of the present embodiment can be further polymerized with, for example, (meth) acrylate having a C 1-6 alkyl group, a polar monomer, or the like.

Examples of the (meth) acrylate having an alkyl group having 1 to 6 carbon atoms include methyl (meth) acrylate, ethyl (meth) acrylate, butyl (meth) acrylate, hexyl (meth) acrylate, and the like. You may use a seed | species or 2 or more types in mixture.

Examples of polar monomers include ethylenically unsaturated monomers having a carboxyl group such as acrylic acid, methacrylic acid, crotonic acid, itaconic acid, maleic acid and fumaric acid; 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl Examples thereof include ethylenically unsaturated monomers having a hydroxyl group such as (meth) acrylate and 2-hydroxyhexyl (meth) acrylate, and these may be used alone or in combination of two or more.

Each of the above-mentioned monomers is, for example, 20 to 100 parts by weight of (meth) acrylate having a linear alkyl group having 16 or more carbon atoms, and 0 to 70 parts by weight of (meth) acrylate having an alkyl group having 1 to 6 carbon atoms. It is preferable to polymerize the polar monomer at a ratio of 0 to 10 parts by weight.

Further, for example, a reactive fluorine compound can be further polymerized to the side chain crystalline (meth) acrylic polymer of the present embodiment. Thereby, in addition to the reduction in the adhesive strength due to the side-chain crystalline (meth) acrylic polymer, the releasability due to the reactive fluorine compound is added, so that the peelability of the pressure-sensitive adhesive composition can be improved.

The reactive fluorine compound means a fluorine compound having a reactive functional group. Examples of the functional group showing reactivity include a group having an ethylenically unsaturated double bond such as vinyl group, allyl group, (meth) acryl group, (meth) acryloyl group, (meth) acryloyloxy group; epoxy group (Including glycidyl group and epoxycycloalkyl group), mercapto group, carbinol group, carboxyl group, silanol group, phenol group, amino group, hydroxyl group and the like.

Specific examples of the reactive fluorine compound include compounds represented by the following general formula (I).

[Wherein R ₁ represents a group: CH ₂ ═CHCOOR ² — or CH ₂ ═C (CH ₃ ) COOR ² — (wherein R ² represents an alkylene group). ]

In general formula (I), as the alkylene group represented by R ² , for example, methylene group, ethylene group, trimethylene group, methylethylene group, propylene group, tetramethylene group, pentamethylene group, hexamethylene group, etc. -6 straight chain or branched alkylene groups.

Specific examples of the compound represented by the general formula (I) include compounds represented by the following formulas (Ia) and (Ib).

Commercially available products can be used as the reactive fluorine compound described above. Examples of commercially available reactive fluorine compounds include “Biscoat 3F”, “Biscoat 3FM”, “Biscoat 4F”, “Biscoat 8F”, “Biscoat 8FM” manufactured by Osaka Organic Chemical Industry Co., Ltd., Kyoeisha Chemical Co., Ltd. “Light Ester M-3F” manufactured by the same company.

The reactive fluorine compound is preferably polymerized with the above-mentioned monomer at a ratio of 1 to 10 parts by weight.

Also, the side chain crystalline (meth) acrylic polymer of the present embodiment can be further polymerized with, for example, (meth) acrylate having an ethylene glycol group, high acrylate acrylate, vinyl monomer and the like. Examples of the (meth) acrylate having an ethylene glycol group include 2-ethylhexyl-diglycol (meth) acrylate, methoxyethyl (meth) acrylate, methoxypolyethylene glycol mono (meth) acrylate, ethoxy-diethylene glycol (meth) acrylate, methoxy -Triethylene glycol (meth) acrylate and the like may be mentioned, and these may be used alone or in combination of two or more. Examples of the high Tg acrylate include isobornyl acrylate (light acrylate IB-XA: Kyoeisha Chemical), isobornyl methacrylate (light ester IB-X: Kyoeisha Chemical), methyl methacrylate, tertiary butyl cyclohexyl methacrylate (TBCHMA: NOF), dicyclopentanyl acrylate (FA513-AS: Hitachi Chemical), dicyclopentanyl methacrylate (FA513-M: Hitachi Chemical), 1-adamantyl acrylate (ADA: Osaka Organic Chemical), 1-adamantyl methacrylate (ADMA) : Osaka Organic Chemistry) and the like. These may be used alone or in combination of two or more. Examples of the vinyl monomer include styrene and vinyl acetate, and these may be used as a mixture. The ratio when each of the above-described (meth) acrylate having an ethylene glycol group, a high Tg acrylate, and a vinyl monomer is polymerized is not particularly limited.

On the other hand, the melting point of the side chain crystalline (meth) acrylic polymer is preferably 5 to 80 ° C., more preferably 10 to 70 ° C. The melting point can be adjusted by changing the composition of the side chain crystalline (meth) acrylic polymer. Further, the melting point tends not to change substantially before and after UV irradiation. That is, the melting point after UV curing tends to be substantially the same value as the melting point before UV curing.

The weight average molecular weight of the side chain crystalline (meth) acrylic polymer is preferably 450,000 or more, more preferably 1 million or more, further preferably 2 million or more, and 24.5 million or more. Is more preferable. The upper limit of the weight average molecular weight of the side chain crystalline (meth) acrylic polymer is preferably 3 million or less, but is not limited thereto. The weight average molecular weight is a value obtained by measuring by gel permeation chromatography (GPC) and converting the obtained measurement value to standard polystyrene. Examples of the measurement solvent for GPC include tetrahydrofuran (THF).

The above-described monomer polymerization is preferably performed by bulk polymerization. Thereby, an adhesive composition can be made into the state which does not contain an organic solvent. The bulk polymerization is preferably performed while irradiating UV. Thereby, the monomer can be polymerized in a relatively short time. Therefore, the side-chain crystalline (meth) acrylic polymer of this embodiment is obtained by adding a photoradical initiator, which will be described later, to a monomer containing a (meth) acrylate having a linear alkyl group having at least 16 carbon atoms. It is preferable that the polymer is polymerized by bulk polymerization while irradiating. The term “monomer” is not limited to an acrylic monomer, but includes a reactive fluorine compound and the like as long as it includes a (meth) acrylate having a linear alkyl group having at least 16 carbon atoms. is there.

The polymerization temperature in the bulk polymerization is preferably 30 to 60 ° C. The polymerization time is preferably 30 seconds to 5 minutes. The intensity of UV is preferably 1 to 100 mW / cm ² (365 nm). The polymerization conditions are not limited to the polymerization conditions described above as long as the side chain crystalline (meth) acrylic polymer can be synthesized.

Bulk polymerization may be performed in the presence of a chain transfer agent in order to control the molecular weight. The addition amount of the chain transfer agent is preferably 0.1 to 10 parts by weight with respect to 100 parts by weight of the monomer. Examples of the chain transfer agent include thiol chain transfer agents such as dodecyl mercaptan, but are not limited thereto.

[(Meth) acrylic monomer]
As described above, the pressure-sensitive adhesive composition of the present embodiment contains a (meth) acrylic monomer. The pressure-sensitive adhesive composition of the present embodiment is liquid due to containing a (meth) acrylic monomer. Therefore, the pressure-sensitive adhesive composition of the present embodiment can exhibit excellent coating properties. Moreover, since the adhesive composition of this embodiment is liquid, it is not necessary to contain an organic solvent like the conventional temperature-sensitive adhesive. Therefore, according to the pressure-sensitive adhesive composition of the present embodiment, there is no problem due to the inclusion of the organic solvent described above, and it is possible to form a thick pressure-sensitive adhesive layer having excellent pressure-sensitive adhesive properties.

In order to reliably obtain the effects described above, it is preferable that the pressure-sensitive adhesive composition of this embodiment does not contain an organic solvent. In the present embodiment, liquid means that the viscosity at 50 ° C. of the mixture containing at least the side chain crystalline (meth) acrylic polymer and the (meth) acrylic monomer is 100 to 10,000 mPa · s. It shall be. The viscosity is a value before UV curing, and is a value obtained by measurement by the method described in Examples described later.

The pressure-sensitive adhesive composition preferably has the largest total content of side chain crystalline (meth) acrylic polymer and (meth) acrylic monomer. Thereby, an adhesive composition will contain a side chain crystalline (meth) acrylic polymer and a (meth) acryl monomer as a main component, As a result, the outstanding coating property and adhesive physical property can be exhibited.

Further, the pressure-sensitive adhesive composition comprises 5 to 40% by weight of the side chain crystalline (meth) acrylic polymer with respect to 100% by weight of the total of the side chain crystalline (meth) acrylic polymer and the (meth) acrylic monomer. Preferably, it is contained in a proportion of 10 to 30% by weight. In other words, the pressure-sensitive adhesive composition contains 60 to 95% by weight of the (meth) acrylic monomer with respect to 100% by weight of the total of the side chain crystalline (meth) acrylic polymer and the (meth) acrylic monomer. The content is preferably 70 to 90% by weight. According to these configurations, the pressure-sensitive adhesive composition has an appropriate viscosity, and therefore can exhibit excellent coating properties, and suppresses the (meth) acrylic monomer remaining after UV curing. As a result, excellent adhesive properties can be exhibited.

Here, the (meth) acrylic monomer of this embodiment is the same as the monomer constituting the side chain crystalline (meth) acrylic polymer. Thereby, the (meth) acryl monomer can exhibit excellent compatibility with the side chain crystalline (meth) acrylic polymer. The (meth) acrylic monomer of the present embodiment corresponds to a residual monomer when the above-described monomers constituting the side chain crystalline (meth) acrylic polymer are polymerized. Therefore, as the (meth) acrylic monomer, the same monomer as exemplified in the above-mentioned side chain crystalline (meth) acrylic polymer, that is, (meth) acrylate having a linear alkyl group having 16 or more carbon atoms, carbon number Examples thereof include (meth) acrylates having 1 to 6 alkyl groups and polar monomers.

In the present embodiment, it is preferable to polymerize the above-described monomers constituting the side chain crystalline (meth) acrylic polymer so that the side chain crystalline (meth) acrylic polymer and the (meth) acrylic monomer coexist with each other. Specifically, the ratio of the side-chain crystalline (meth) acrylic polymer is 5 to 40% by weight, preferably 10% with respect to 100% by weight of the total of the side-chain crystalline (meth) acrylic polymer and the (meth) acrylic monomer. It is preferable to polymerize the above-described monomer so that it is ˜30% by weight.

[Multifunctional (meth) acrylate]
The polyfunctional (meth) acrylate is a curable compound having a property of curing when irradiated with UV, and is a (meth) acrylate having two or more double bonds capable of radical polymerization in the molecule. Since the pressure-sensitive adhesive composition of the present embodiment contains a polyfunctional (meth) acrylate as described above, the cohesive force can be improved after UV curing, and as a result, excellent heat resistance can be exhibited. .

The pressure-sensitive adhesive composition comprises 0.1 to 30 parts by weight of a polyfunctional (meth) acrylate with respect to 100 parts by weight in total of the side chain crystalline (meth) acrylic polymer, the (meth) acrylic monomer, and the photoradical initiator. It is preferable to contain by a ratio.

The polyfunctional (meth) acrylate is preferably bifunctional (meth) acrylate or trifunctional (meth) acrylate and has a weight average molecular weight of 200 to 1,200.

Examples of the polyfunctional (meth) acrylate include 1,6-hexanediol di (meth) acrylate, ethoxylated bisphenol A di (meth) acrylate, and ε-caprolactone-modified tris- (2-acryloxyethyl) isocyanurate. These may be used, and one kind or a mixture of two or more kinds may be used.

Commercially available products can be used for the polyfunctional (meth) acrylates described above. Examples of commercially available polyfunctional (meth) acrylates include “NK Ester A-HD-N”, “NK Ester A-BPE-10”, and “NK Ester A-9300-1CL” manufactured by Shin-Nakamura Chemical Co., Ltd. , “NK ester A-9300-6CL” and the like.

[Photo radical initiator]
As described above, the pressure-sensitive adhesive composition of the present embodiment contains a photo radical initiator. The photoradical initiator is not particularly limited as long as it is a compound that can initiate radical polymerization by receiving light irradiation. The photoradical initiator of the present embodiment is used at the time of polymerization of the above-described monomers constituting the side chain crystalline (meth) acrylic polymer, and is also used at the time of UV curing of the pressure-sensitive adhesive composition.

The pressure-sensitive adhesive composition contains a photoradical initiator in a proportion of 0.2 to 1.9 parts by weight with respect to 100 parts by weight of the total of the side chain crystalline (meth) acrylic polymer and the (meth) acrylic monomer. Is preferred. The total amount of the photo radical initiator may be added all at once during the polymerization of the monomer, or may be added separately during the polymerization of the monomer and during the UV curing of the pressure-sensitive adhesive composition.

Commercially available products can be used as the above-mentioned photo radical initiator. Examples of commercially available photo radical initiators include “IRGACURE 184” and “IRGACURE 500” manufactured by BASF Japan.

Various additives such as a tackifier, an anti-aging agent, and a crosslinking agent can be added to the pressure-sensitive adhesive composition of the present embodiment described above.

The use of the pressure-sensitive adhesive composition of the present embodiment is not particularly limited. For example, a pressure-sensitive adhesive tape having a thick pressure-sensitive adhesive layer is required so as to follow the level difference of the adherend. It can be suitably used as a pressure-sensitive adhesive composition in certain fields.

<Temperature sensitive adhesive tape>
Next, the temperature sensitive adhesive tape which concerns on one Embodiment of this invention is demonstrated.
The temperature-sensitive adhesive tape of this embodiment includes a base material and an adhesive layer.

(Base material)
The base material of this embodiment is a film form. The film shape is not limited to a film shape, and is a concept including a film shape or a sheet shape as long as the effects of the present embodiment are not impaired. Examples of the constituent material of the base material include polyethylene, polyethylene terephthalate, polypropylene, polyester, polyamide, polyimide, polycarbonate, ethylene vinyl acetate copolymer, ethylene ethyl acrylate copolymer, ethylene polypropylene copolymer, and polyvinyl chloride. Synthetic resins are mentioned.

The substrate may be either a single layer or a multilayer, and the thickness is usually about 5 to 500 μm. The substrate can be subjected to surface treatment such as corona discharge treatment, plasma treatment, blast treatment, chemical etching treatment, primer treatment, etc. in order to improve the adhesion to the pressure-sensitive adhesive layer.

(Adhesive layer)
The pressure-sensitive adhesive layer of this embodiment is laminated on one side or both sides of the above-mentioned base material, and the temperature-sensitive pressure-sensitive adhesive composition according to the above-described embodiment is applied to the base material, and UV is applied. It consists of the hardened | cured material hardened by irradiating. Here, the pressure-sensitive adhesive composition is excellent in coating properties for the reasons described above, and has no problem due to containing an organic solvent. Therefore, the temperature-sensitive adhesive tape of the present embodiment has no bubbles generated due to volatilization of the organic solvent in the adhesive layer, and can increase the thickness of the adhesive layer, resulting in excellent adhesive properties. It can be demonstrated.

Specifically, according to this embodiment, the thickness of the pressure-sensitive adhesive layer can be set from a wide range of 1 to 1,000 μm, preferably 40 to 500 μm. For example, when a thick adhesive layer is required so as to follow and adhere to the level difference of the adherend, the thickness of the adhesive layer can be set larger from the exemplified range. The thickness of the pressure-sensitive adhesive layer on one side and the thickness of the pressure-sensitive adhesive layer on the other side may be the same or different.

The amount of UV irradiation is preferably 1,000 mJ / cm ² or more. The upper limit value of the UV irradiation amount is preferably 10,000 mJ / cm ² or less, but is not limited thereto.

When irradiating UV, it is preferable to laminate a film-like air blocking member on the surface of the coating film made of the pressure-sensitive adhesive composition. Thereby, UV can be irradiated and hardened | cured to an adhesive composition in the state which interrupted | blocked air. Examples of the air blocking member include those obtained by applying a release agent such as silicone or silicon to the surface of a film made of polyethylene terephthalate or the like.

In addition, as an application means for applying the pressure-sensitive adhesive composition to the above-described substrate, for example, an applicator, a coater and the like can be mentioned. Examples of the coater include a knife coater, a roll coater, a calendar coater, a comma coater, a gravure coater, and a rod coater.

Moreover, in this embodiment, as long as the adhesive layer of one side consists of the adhesive composition mentioned above, the adhesive layer of another side is not specifically limited. For example, when the pressure-sensitive adhesive layer on the other side is composed of a pressure-sensitive adhesive layer composed of the pressure-sensitive adhesive composition described above, the composition may be the same as or different from the composition of the pressure-sensitive adhesive layer on one side. Good.

Further, the pressure-sensitive adhesive layer on the other surface can be constituted by, for example, a pressure-sensitive adhesive layer made of a pressure-sensitive adhesive. The pressure-sensitive adhesive is a tacky polymer, and examples thereof include natural rubber adhesives, synthetic rubber adhesives, styrene / butadiene latex-based adhesives, and acrylic adhesives.

It is preferable to laminate a release film on the surface of the temperature-sensitive adhesive tape described above. Examples of the release film include a film made of polyethylene terephthalate or the like and a release agent such as silicone or silicon applied to the surface of the film.

<Temperature sensitive adhesive sheet>
Next, the temperature sensitive adhesive sheet which concerns on one Embodiment of this invention is demonstrated.
The temperature-sensitive adhesive sheet of the present embodiment is formed of a cured product obtained by processing the pressure-sensitive adhesive composition according to the above-described embodiment into a sheet shape and irradiating it with UV. The thickness of the temperature-sensitive adhesive sheet is preferably 1 to 1,000 μm, more preferably 40 to 500 μm. The upper limit of the thickness of the thermosensitive adhesive sheet is not particularly limited as long as it can be cured by UV irradiation.
Since the other structure is the same as that of the temperature-sensitive adhesive tape which concerns on one Embodiment mentioned above, description is abbreviate | omitted.

The preferred embodiments according to the present invention have been described above, but the present invention is not limited to the above-described embodiments, and it goes without saying that the embodiments can be arbitrarily set without departing from the gist of the present invention.

For example, in the above-described embodiment, the case where the (meth) acrylic monomer is a residual monomer obtained by polymerizing the monomer constituting the side chain crystalline (meth) acrylic polymer has been described. An acrylic monomer may be contained in the pressure-sensitive adhesive composition as a new monomer instead of a residual monomer. Further, when the (meth) acrylic monomer is a residual monomer when the monomer constituting the side chain crystalline (meth) acrylic polymer is polymerized, a new (meth) acrylic monomer may be further contained in the pressure-sensitive adhesive composition. Good.

In the above-described embodiment, the case where the use form of the pressure-sensitive adhesive composition is a temperature-sensitive pressure-sensitive adhesive tape and a temperature-sensitive pressure-sensitive adhesive sheet has been described, but instead, the pressure-sensitive adhesive composition is directly applied to an adherend. , UV may be irradiated and cured.

Hereinafter, the present invention will be described in more detail with reference to synthesis examples and examples, but the present invention is not limited to the following synthesis examples and examples.

(Synthesis Example 1)
First, 135 g of behenyl acrylate, 150 g of methyl acrylate, 15 g of acrylic acid, and a photoradical initiator (photopolymerization initiator) are placed in a 500 ml flask equipped with a nitrogen introduction tube, a thermometer, a cooling tube and a UV irradiation head at the top of the flask. ) “IRGACURE 500” manufactured by BASF Japan Ltd. was added at a rate of 3 g to obtain a mixed solution.

Next, the flask was immersed in a hot water bath, the mixture was heated to 40 ° C., and nitrogen was bubbled for 30 minutes while stirring at 150 rpm to remove oxygen in the mixture. Then, the monomer was bulk polymerized while irradiating the mixture with UV from a UV irradiation head at the top of the flask.

The conditions for bulk polymerization are as follows.
Polymerization temperature: 40 ° C
Polymerization time: 2 minutes UV intensity: 40 mW / cm ² (365 nm)

The liquid mixture of the side chain crystalline (meth) acrylic polymer and the (meth) acrylic monomer (behenyl acrylate, methyl acrylate, acrylic acid) was obtained by the bulk polymerization described above. The weight average molecular weight of the side chain crystalline (meth) acrylic polymer, the content of the side chain crystalline (meth) acrylic polymer and the (meth) acrylic monomer, and the viscosity of the liquid mixture were measured in the obtained liquid mixture. Each measurement result and measurement method are as follows.

Weight average molecular weight of side chain crystalline (meth) acrylic polymer: 2.5 million Content of side chain crystalline (meth) acrylic polymer: 18% by weight
Content of (meth) acrylic monomer: 82% by weight
Viscosity of liquid mixture: 800 mPa · s

(Weight average molecular weight)
It measured by GPC, and the obtained measured value was obtained by standard polystyrene conversion. THF was used as a measurement solvent for GPC.

(Content)
In the measurement result of the weight average molecular weight described above, it was calculated from the detection area ratio of the polymer component and the monomer component.

(viscosity)
The measurement was performed under the following measurement conditions.
Measuring device: Digital viscometer “DV-II + Pro” manufactured by Eihiro Seiki Co., Ltd.
Cone plate: CPE-42
Rotation speed: 30rpm
Measurement temperature: 50 ° C

(Synthesis Example 2)
Except for adding 0.3 g of dodecyl mercaptan as a chain transfer agent, the monomers were bulk polymerized while being irradiated with UV in the same manner as in Synthesis Example 1 described above, and the side chain crystalline (meth) acrylic polymer ( A liquid mixture with a (meth) acrylic monomer was obtained.

Synthesis example in which the weight average molecular weight of the side chain crystalline (meth) acrylic polymer, the content of the side chain crystalline (meth) acrylic polymer and the (meth) acrylic monomer, and the viscosity of the liquid mixture in the obtained liquid mixture are described above. Measurement was performed in the same manner as in 1. The measurement results are as follows.

Weight average molecular weight of side chain crystalline (meth) acrylic polymer: 500,000 Content of side chain crystalline (meth) acrylic polymer: 20% by weight
Content of (meth) acrylic monomer: 80% by weight
Viscosity of liquid mixture: 200 mPa · s

(Comparative synthesis example)
First, 45 g of behenyl acrylate, 50 g of methyl acrylate, 5 g of acrylic acid, and “Perbutyl ND” manufactured by NOF Corporation as a polymerization initiator are placed in a 500 ml flask equipped with a nitrogen introduction tube, a thermometer and a cooling tube at the top of the flask. Was added at a rate of 0.5 g to obtain a mixture. Next, a mixed solvent of ethyl acetate: heptane = 7: 3 (weight ratio) was added to the flask, and the concentration of the mixture was adjusted to be 30 parts by weight in terms of solid content to obtain a mixed solution.

Then, the above mixed solution was stirred at 55 ° C. for 4 hours to polymerize these monomers to obtain a polymer solution. The weight average molecular weight of the polymer in the obtained polymer solution and the viscosity of the polymer solution were measured in the same manner as in Synthesis Example 1 described above. The measurement results are as follows.

Weight average molecular weight of polymer: 600,000 Viscosity of polymer solution: 1,000 mPa · s

[Examples 1 to 4]
<Manufacture of temperature-sensitive adhesive tape>
As the coating liquid, the liquid mixture obtained in Synthesis Example 1 was used. First, polyfunctional acrylate was added to 100 g of this liquid mixture.

The added polyfunctional acrylate is as follows.
Multifunctional acrylate: 1,6-hexanediol diacrylate “NK Ester A-HD-N” manufactured by Shin-Nakamura Chemical Co., Ltd.

The amount of polyfunctional acrylate added to 100 g of the liquid mixture is as follows.
Example 1: 0.5 g
Example 2: 0.5 g
Example 3: 1.0 g
Example 4: 1.0 g

Next, the liquid mixture to which the polyfunctional acrylate was added was applied to one side of the film-like substrate with an applicator.

The used film-like base materials are as follows.
Substrate: 100 μm thick polyethylene terephthalate film “Embret SB-100” manufactured by Unitika Co., Ltd. with one side corona-treated

The gap of the applicator is as follows.
Example 1: 10 mil
Example 2: 5 mil
Example 3: 5 mil
Example 4: 10 mil

Next, a film-like air blocking member was laminated on the surface of the coating film, and UV was irradiated from above the coating film.

The air blocking member used is as follows.
Air blocking member: 25 μm thick polyethylene terephthalate film “PET25 × 1-J0L” manufactured by Nipper Co., Ltd.

The UV irradiation conditions are as follows.
UV irradiation device: “HLR100T-2 / HB100A-1” manufactured by ASONE
UV amount: 1,500 mJ / cm ²

The temperature sensitive adhesive tape which provided the adhesive layer which has the thickness shown in Table 1 on the single side | surface of a film-like base material by irradiating UV on the conditions mentioned above was obtained. In addition, the thickness of the adhesive layer in Table 1 is a value obtained by measuring with a dial gauge.

<Evaluation>
About the obtained temperature-sensitive adhesive tape, the state of the adhesive layer and the 180 ° peel strength were evaluated. Each evaluation method is shown below, and the results are shown in Table 1.

(Adhesive layer state)
The presence or absence of air bubbles was evaluated by visually observing the pressure-sensitive adhesive layer of the temperature-sensitive pressure-sensitive adhesive tape. The evaluation criteria were set as follows.
A: There were no bubbles in the pressure-sensitive adhesive layer.
Δ: A small number of bubbles were present in the pressure-sensitive adhesive layer.
X: Many air bubbles existed in the adhesive layer.

(180 ° peel strength)
About the obtained temperature-sensitive adhesive tape, a stainless steel plate (hereinafter referred to as “SUS plate”) at each ambient temperature of 23 ° C. after passing through 80 ° C., 80 ° C., 23 ° C., 120 ° C. and 120 ° C. 180 ° peel strength was measured according to JIS Z0237. Specifically, a temperature-sensitive adhesive tape was attached to a SUS plate under the following conditions, and then peeled 180 ° using a load cell at a speed of 300 mm / min.

[80 ° C]
With the temperature sensitive adhesive tape attached to the SUS plate, the ambient temperature was set to 80 ° C., left at this ambient temperature for 20 minutes, and then peeled 180 °.

[23 ° C after 80 ° C]
After the ambient temperature is set to 80 ° C. with the temperature-sensitive adhesive tape attached to the SUS plate and left at this ambient temperature for 20 minutes, the ambient temperature is lowered to 23 ° C. and left at this ambient temperature for 20 minutes. , Peeled 180 °.

[120 ° C]
With the temperature-sensitive adhesive tape attached to the SUS plate, the ambient temperature was set to 120 ° C., left at this ambient temperature for 20 minutes, and then peeled 180 °.

[23 ° C. after 120 ° C.]
After the ambient temperature is set to 120 ° C. with the temperature-sensitive adhesive tape attached to the SUS plate and left at this ambient temperature for 20 minutes, the ambient temperature is lowered to 23 ° C. and left at this ambient temperature for 20 minutes. , Peeled 180 °.

[Example 5]
A feeling that a pressure-sensitive adhesive layer having a thickness shown in Table 1 is provided on one side of a film-like substrate in the same manner as in Example 1 except that the liquid mixture obtained in Synthesis Example 2 was used as the coating liquid. A warm adhesive tape was obtained.

About the obtained temperature sensitive adhesive tape, it carried out similarly to Example 1 mentioned above, and evaluated the state and 180 degree peel strength of the adhesive layer. The results are shown in Table 1.

[Comparative Example 1]
First, 135 g of behenyl acrylate, 150 g of methyl acrylate, 15 g of acrylic acid, and 3 g of “IRGACURE 500” manufactured by BASF Japan Ltd. as a photo radical initiator (photo polymerization initiator) Functional acrylate was added at a ratio of 0.5 g to obtain a coating solution. The same polyfunctional acrylate as in Example 1 was used.

Except having used the obtained coating liquid, the adhesive tape which provides the adhesive layer which has the thickness shown in Table 1 on the single side | surface of a film-like base material similarly to Example 1 mentioned above was obtained.

About the obtained adhesive tape, it carried out similarly to Example 1 mentioned above, and evaluated the state and 180 degree peel strength of the adhesive layer. The results are shown in Table 1.

[Comparative Examples 2 to 5]
As the coating solution, the polymer solution obtained in the comparative synthesis example was used. First, triethylamine was added at a rate of 9 g to 100 g of this polymer solution, and a crosslinking agent was further added.

The added crosslinking agent is as follows.
Cross-linking agent: aziridine compound “Chemite PZ-33” manufactured by Nippon Shokubai Co., Ltd.

The amount of the crosslinking agent added to 100 g of the polymer solution is as follows.
Comparative Example 2: 0.5 g
Comparative Example 3: 0.5 g
Comparative Example 4: 0.5 g
Comparative Example 5: 1.0 g

Next, a polymer solution to which triethylamine and a crosslinking agent were added was applied to one side of a film-like substrate with an applicator. The same substrate as in Example 1 was used.

The gap of the applicator is as follows.
Comparative Example 2: 10 mil
Comparative Example 3: 15 mil
Comparative Example 4: 20 mil
Comparative Example 5: 10 mil

Then, the crosslinking agent was subjected to a crosslinking reaction by heating in a hot air oven at 110 ° C. for 10 minutes to obtain an adhesive tape having an adhesive layer having a thickness shown in Table 1 on one side of the film-like substrate.

As can be seen from Table 1, in all of Examples 1 to 5, there are no bubbles in the pressure-sensitive adhesive layer, the thickness of the pressure-sensitive adhesive layer can be increased, and the adhesive properties are excellent. For Examples 1 to 5, the pressure-sensitive adhesive layer was collected from the temperature-sensitive adhesive tape after UV curing, and the melting point of the side chain crystalline (meth) acrylic polymer was measured by DSC under the measurement conditions of 10 ° C./min. As a result, the melting points of Examples 1 to 5 were 55 ° C.

On the other hand, in Comparative Example 1, when an adhesive layer having a thickness larger than 10 μm was formed, dripping occurred and the coating could not be performed. In Comparative Examples 2 to 5, more bubbles were generated as the thickness of the pressure-sensitive adhesive layer was increased. In Comparative Examples 3 and 4, a tape could not be produced.

Claims

A temperature-sensitive adhesive that contains at least a side-chain crystalline (meth) acrylic polymer, a (meth) acrylic monomer, a polyfunctional (meth) acrylate, and a photoradical initiator, and is UV-curable and liquid. Composition.
Polymer in which the side chain crystalline (meth) acrylic polymer is bulk polymerized while adding a photo radical initiator to a monomer containing (meth) acrylate having a linear alkyl group having at least 16 carbon atoms and irradiating ultraviolet rays The temperature-sensitive adhesive composition according to claim 1, wherein
The temperature-sensitive adhesive composition according to claim 1 or 2, wherein the side chain crystalline (meth) acrylic polymer has a weight average molecular weight of 450,000 or more.
Among the side chain crystalline (meth) acrylic polymer, the (meth) acrylic monomer, the polyfunctional (meth) acrylate, and the photo radical initiator, the side chain crystalline (meth) acrylic polymer and the (meth) acrylic The temperature-sensitive adhesive composition according to any one of claims 1 to 3, wherein the total monomer content is the highest.
The side chain crystalline (meth) acrylic polymer is contained in a proportion of 5 to 40% by weight with respect to a total of 100% by weight of the side chain crystalline (meth) acrylic polymer and the (meth) acrylic monomer. 5. The temperature-sensitive adhesive composition according to any one of 1 to 4.
The temperature-sensitive adhesive composition according to any one of claims 1 to 5, which does not contain an organic solvent.
The adhesive strength is exhibited at a temperature equal to or higher than the melting point of the side-chain crystalline (meth) acrylic polymer after ultraviolet curing, and the adhesive strength is decreased at a temperature lower than the melting point. Temperature-sensitive adhesive composition.
The temperature-sensitive adhesive composition according to any one of claims 1 to 7, wherein the (meth) acrylic monomer is the same as the monomer constituting the side chain crystalline (meth) acrylic polymer.
A film-like substrate;
A pressure-sensitive adhesive layer laminated on one side or both sides of the base material,
A temperature-sensitive adhesive tape, wherein the pressure-sensitive adhesive layer comprises a cured product of the temperature-sensitive adhesive composition according to any one of claims 1 to 8.
A temperature-sensitive adhesive sheet comprising a cured product of the temperature-sensitive adhesive composition according to any one of claims 1 to 8.
A temperature-sensitive adhesive that contains at least a side-chain crystalline (meth) acrylic polymer, a (meth) acrylic monomer, a polyfunctional (meth) acrylate, and a photoradical initiator, and is UV-curable and liquid. A method for producing a composition comprising:
The side chain crystalline (meth) acrylic polymer is obtained by bulk polymerization while adding a photo radical initiator to a monomer containing a (meth) acrylate having a linear alkyl group having at least 16 carbon atoms and irradiating with ultraviolet rays. A method for producing a temperature-sensitive adhesive composition.