JP7435889B1 - Adhesive sheets and laminates - Google Patents

Abstract

[Problem] This product is used for bonding adherends with different expansion and contraction ratios, and peeling occurs from the adherends in both environments where temperature changes occur and high-temperature environments. Provides a durable adhesive sheet. [Solution] The adhesive sheet of the present invention is used for bonding a pair of adherends having different expansion/contraction ratios, includes an adhesive layer obtained from an adhesive composition, and comprises an adhesive layer obtained from an adhesive composition. The adhesive composition contains at least a main ingredient containing a (meth)acrylic polymer and a silane coupling agent, the adhesive layer has a gel fraction of 80% or more, and the adhesive layer has a gel fraction of 15% at 105°C. % residual stress 60 seconds after application of torsional shear stress is 3.0 kPa or more and 10.0 kPa or less. [Selection diagram] None

Description

The present invention relates to an adhesive sheet and a laminate.

In recent years, adhesive sheets, for example, are materials formed with an adhesive layer mainly composed of acrylic polymers, and are used for bonding various optical components such as touch panels and liquid crystal displays (LCDs). It is also applied to automobile sunroofs and large windows in buildings.

Such pressure-sensitive adhesive sheets have been widely studied, and various means have been proposed to improve not only the adhesive force but also various performances. For example, Patent Document 1 proposes a pressure-sensitive adhesive sheet with a release liner, which includes a pressure-sensitive adhesive sheet having a base material and a pressure-sensitive adhesive layer, and a release liner disposed on the pressure-sensitive adhesive layer. It is said that when it is pasted on an adherend, air can escape easily and it can be pasted with good adhesion.

On the other hand, a pair of adherends having different coefficients of linear expansion (stretching/contraction) may be bonded together using an adhesive sheet. For example, a laminate in which a glass base material and a resin base material are bonded to each other with an adhesive sheet is known. It is also known that such a laminate can be applied to various uses such as, for example, sunroofs for automobiles and large windows for buildings.

Japanese Patent Application Publication No. 2011-094057

However, in a laminate in which adherends with different expansion and contraction rates are bonded together using a conventional adhesive sheet, under environments where temperature changes occur or in high-temperature environments, due to the difference in expansion and contraction rates between each other, for example, the adhesion There is a problem of peeling occurring at the ends of the body. Such problems become more pronounced as the adherend becomes larger; for example, the thicker the adherend, the more likely it is that peeling will occur in an environment where temperature changes occur or under a high-temperature environment. From this point of view, there has been a desire for an adhesive sheet that does not easily peel off even when placed in a temperature-changing environment or a high-temperature environment when adherends having different expansion/contraction rates are bonded together.

The present invention has been made in view of the above, and when adherends with different expansion/contraction ratios are bonded together, it is possible to adhere them even under environments where temperature changes occur or under high temperature environments. The purpose of the present invention is to provide an adhesive sheet that does not easily peel off from the body.

As a result of extensive research to achieve the above object, the present inventors have discovered that the above object can be achieved by using an adhesive layer having specific physical properties, and have completed the present invention.

That is, the present invention includes, for example, the subject matter described in the following sections.
Item 1
An adhesive sheet used for bonding a pair of adherends having different expansion and contraction ratios,
comprising an adhesive layer obtained from an adhesive composition,
The adhesive composition contains at least a base agent containing a (meth)acrylic polymer and a silane coupling agent,
The adhesive layer has a gel fraction of 80% or more,
The adhesive layer has a residual stress of 3.0 kPa or more and 10.0 kPa or less after 60 seconds after applying 15% torsional shear stress at 105 ° C.,
The following formula (1)
|(X1-X2)|≧0.1%...(1)
(Here, when one of the pair of adherends is referred to as adherend A and the other as adherend B, X1 is the expansion/contraction rate (%) when adherend A is heated from 23°C to 110°C. , X2 is the expansion/contraction rate (%) when adherend B is heated from 23°C to 110°C)
Adhesive sheet that meets the requirements.
Section 2
Item 2. The pressure-sensitive adhesive sheet according to Item 1, wherein the pressure-sensitive adhesive composition contains a monofunctional monomer having a ring structure.
Section 3
Item 3. The adhesive sheet according to item 1 or 2, wherein the adhesive composition contains the silane coupling agent in an amount of 0.05 parts by mass or more and 5 parts by mass or less based on 100 parts by mass of the main agent.
Section 4
The adhesive composition is solvent-free,
Item 4. The adhesive sheet according to any one of Items 1 to 3, wherein the adhesive layer has a crosslinked structure using a polyfunctional monomer.
Item 5
Item 5. The adhesive sheet according to any one of Items 1 to 4, wherein the adhesive composition contains an acrylic tackifier.
Item 6
Item 5. The adhesive sheet according to any one of Items 1 to 5, having a thickness of 75 μm or more.
Section 7
Item 7. The pressure-sensitive adhesive sheet according to any one of Items 1 to 6, wherein the adherend having a higher expansion/contraction rate among the adherend A and the adherend B has a thickness of 2 mm or more.
Section 8
8. The adhesive sheet according to any one of Items 1 to 7, wherein both the adherend A and the adherend B have a total light transmittance of 50% or more.
Section 9
Item 8. The adhesive sheet according to item 8, which is used for car windows, building material windows, or door windows.
Item 10
Item 10. A laminate comprising the adhesive sheet according to any one of Items 1 to 9 and a pair of adherends having different expansion and contraction rates.

The adhesive sheet according to the present invention is used for bonding adherends with different expansion/contraction ratios, and is capable of adhering under both environments where temperature changes occur and high-temperature environments. Less likely to peel off from the body.

Embodiments of the present invention will be described in detail below. Note that, in this specification, the expressions "contain" and "comprising" include the concepts of "containing", "containing", "consisting essentially of", and "consisting only".

The adhesive sheet of the present invention is an adhesive sheet used for bonding adherends having different expansion/contraction ratios, and includes an adhesive layer obtained from an adhesive composition. Here, the adhesive composition contains at least a main ingredient containing a (meth)acrylic polymer and a silane coupling agent, the adhesive layer has a gel fraction of 80% or more, and the adhesive layer has a residual stress of 3.0 kPa or more and 10.0 kPa or less after 60 seconds after applying 15% torsional shear stress at 105°C. In addition, the adhesive sheet of the present invention has
The following formula (1)
|(X1-X2)|≧0.1%...(1)
(Here, when one of the pair of adherends is referred to as adherend A and the other as adherend B, X1 is the expansion/contraction rate (%) when adherend A is heated from 23°C to 110°C. , X2 is the expansion/contraction rate (%) when adherend B is heated from 23°C to 110°C)
satisfy.

The adhesive sheet according to the present invention is used for bonding adherends with different expansion/contraction ratios, and is capable of adhering under both environments where temperature changes occur and high-temperature environments. It is difficult to peel off from the body.

As mentioned above, the adhesive sheet of the present invention is provided with an adhesive layer obtained from an adhesive composition. For example, when the adhesive composition is an active energy ray-curable type described later, such The adhesive layer can be formed by irradiating the adhesive with active energy rays and curing it.

The adhesive composition for forming the adhesive layer contains at least a base agent containing a (meth)acrylic polymer and a silane coupling agent.

(Main agent containing (meth)acrylic polymer)
The base agent containing a (meth)acrylic polymer contains at least a (meth)acrylic polymer and is a main component of the pressure-sensitive adhesive composition. The base material containing a (meth)acrylic polymer may be composed only of a (meth)acrylic polymer, or the base material containing a (meth)acrylic polymer may be a (meth)acrylic polymer as described below. It may also contain a monofunctional monomer. When the base agent containing a (meth)acrylic polymer contains a (meth)acrylic polymer and a monofunctional monomer, the base agent becomes a monomer solution of the (meth)acrylic polymer, and becomes a so-called syrup.

Examples of the (meth)acrylic polymer include a wide range of known acrylic polymers used to form adhesive sheets. For example, the (meth)acrylic polymer may be a (meth)acrylic acid ester polymer. That is, the (meth)acrylic polymer is a polymer having (meth)acrylic acid ester units.

Examples of (meth)acrylic acid esters include (meth)acrylates having a linear or branched alkyl group, (meth)acrylates having a ring structure in the side chain, (meth)acrylates having a hydroxyl group in the side chain, etc. be able to.

In the (meth)acrylate having a linear or branched alkyl group, the number of carbon atoms in the alkyl group can be, for example, 1 to 20, preferably 1 to 15, more preferably 2 to 14, and even more preferably 3. ~12.

Specific examples of (meth)acrylates having a linear or branched alkyl group include methyl (meth)acrylate, ethyl (meth)acrylate, n-butyl (meth)acrylate, t-butyl (meth)acrylate, and isopropyl (meth)acrylate. ) acrylate, isooctyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, nonyl (meth)acrylate, decyl (meth)acrylate, lauryl (meth)acrylate, cetyl (meth)acrylate, stearyl (meth)acrylate, behenyl (meth)acrylate ) acrylate, etc.

The (meth)acrylate having a ring structure in the side chain is preferably a (meth)acrylic monomer having an alicyclic or aromatic ring in the side chain, and more preferably a (meth)acrylic monomer having an alicyclic ring. . Examples of the alicyclic ring include cyclopropane, cyclobutane, cyclopentane, cyclohexane, cycloheptane, cyclooctane, cyclononane, cyclodecane, cycloundecane, cyclododecane, norbornene, norbornadiene, dicyclopentane, isobornyl, tetrahydrofuran, and tetrahydropyran. It will be done. Note that the alicyclic ring may have a spiro structure. Examples of the aromatic ring include benzene, naphthalene, anthracene, pyridine, furan, benzofuran, pyrrole, thiophene, imidazole, and oxazole. Among these, the ring structure is preferably an alicyclic ring, more preferably at least one selected from cyclohexane, dicyclopentane, isobornyl, and benzene, and particularly preferably cyclohexane or isobornyl. In addition, the ring structure mentioned above may further have a substituent. Examples of substituents include halogen atoms, halogenated alkyl groups, alkyl groups, alkenyl groups, acyl groups, hydroxy groups, hydroxyalkyl groups, alkoxy groups, aryl groups, heteroaryl groups, alicyclic groups, cyano groups, and epoxy groups. , an oxetanyl group, a mercapto group, an amino group, a (meth)acryloyl group, and the like.

The (meth)acrylate having a ring structure in the side chain preferably has a structure in which a monovalent group having a ring structure is bonded to the ester oxygen of the (meth)acrylate. In this case, the monovalent group having a ring structure The group preferably has 3 to 12 carbon atoms, more preferably 4 to 10 carbon atoms, and even more preferably 4 to 8 carbon atoms.

Specific examples of (meth)acrylates having a ring structure in the side chain include cyclohexyl (meth)acrylate, dicyclopentanyl (meth)acrylate, dicyclopentenyloxyethyl (meth)acrylate, isobornyl (meth)acrylate, Examples include benzyl (meth)acrylate, phenoxyethyl (meth)acrylate, 3-phenoxybenzyl (meth)acrylate, and O-phenylphenoxyethyl (meth)acrylate. Among them, (meth)acrylates having a ring structure in their side chains are preferred by cyclohexyl (meth)acrylate and One or more types selected from the group consisting of isobornyl (meth)acrylates are preferred.

Examples of (meth)acrylates having a hydroxyl group in the side chain include 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, and 3-chloro-2-hydroxypropyl ( meth)acrylate, 4-hydroxybutyl(meth)acrylate, 6-hydroxyhexyl(meth)acrylate, 5-hydroxypentyl(meth)acrylate, 2-hydroxybutyl(meth)acrylate, 2-hydroxy3-phenoxypropyl(meth)acrylate ) acrylate, 2,2-dimethyl 2-hydroxyethyl (meth)acrylate, 3-chloro 2-hydroxypropyl (meth)acrylate, 2-hydroxy 3-phenoxypropyl (meth)acrylate, 8-hydroxyoctyl (meth)acrylate, Examples include 8-hydroxyoctyl (meth)acrylate and polyalkylene glycol mono(meth)acrylate.

The (meth)acrylic polymer can have other monomer units other than the above-mentioned (meth)acrylic acid ester, such as carboxyl group-containing (meth)acrylate units such as (meth)acrylic acid, glycidyl groups, etc. Examples include (meth)acrylate units containing amino groups, (meth)acrylates containing amino groups, and monomer units based on (meth)acrylamide, allylamine, and the like.

(Meth) acrylic polymers have at least a linear or branched alkyl group, since peeling between the adherend and the adhesive sheet is difficult to occur even in a temperature changing environment or a high temperature environment. It is preferably a polymer of monomers containing one or more selected from the group consisting of acrylate, (meth)acrylate having a ring structure in the side chain, and (meth)acrylate having a hydroxyl group in the side chain. That is, the (meth)acrylic polymer includes (meth)acrylate units having at least a linear or branched alkyl group, (meth)acrylate units having a ring structure in the side chain, and (meth)acrylate units having a hydroxyl group in the side chain. It is preferable that the monomer unit contains one type of monomer unit selected from the group consisting of: In particular, the (meth)acrylic polymer preferably contains (meth)acrylate units having at least a linear or branched alkyl group.

The (meth)acrylic polymer preferably contains 30% by mass or more, more preferably 40% by mass or more, and further preferably contains 50% by mass or more of (meth)acrylate units having a linear or branched alkyl group. Preferably, the content is preferably 90% by mass or less, more preferably 85% by mass or less, and particularly preferably 80% by mass or less.

The (meth)acrylic polymer preferably contains 1% by mass or more of (meth)acrylate having a ring structure in the side chain, more preferably 3% by mass or more, even more preferably 5% by mass or more, and , more preferably 50% by mass or less, even more preferably 40% by mass or less, particularly preferably 30% by mass or less.

The (meth)acrylic polymer preferably contains 10% by mass or more of (meth)acrylate units having a hydroxyl group in the side chain, more preferably 15% by mass or more, still more preferably 20% by mass or more, and , more preferably 50% by mass or less, further preferably 45% by mass or less, particularly preferably 40% by mass or less.

The (meth)acrylic polymer can contain other monomer units other than those mentioned above, as long as the effects of the present invention are not impaired. The content of the other monomer units in the (meth)acrylic polymer can be 20% by mass or less, preferably 15% by mass or less, more preferably 10% by mass or less, and even more preferably 5% by mass. % or less.

Note that the ratio (molar ratio) of each structural unit in the (meth)acrylic polymer can be considered to match the molar ratio of each monomer used for producing the polymer.

(Meth)acrylic polymers are a group consisting of (meth)acrylate units having a linear or branched alkyl group, (meth)acrylate units having a ring structure in the side chain, and (meth)acrylate units having a hydroxyl group in the side chain. It may consist of only one type of monomer unit selected from among the following.

The weight average molecular weight of the (meth)acrylic polymer is preferably greater than 10,000, more preferably 100,000 or more, and even more preferably 200,000 or more. Further, the weight average molecular weight of the (meth)acrylic polymer is preferably 2 million or less, more preferably 1.5 million or less, and even more preferably 1.2 million or less.

Note that the weight average molecular weight as used in the present invention refers to a polystyrene equivalent weight average molecular weight measured by gel permeation chromatography (GPC). There are no particular restrictions on the GPC device used in the GPC method, and commercially available GPC measurement devices, such as the LC-2000Plus series manufactured by JASCO Corporation, and the detectors RI-2031Plus and UV-2075Plus, can be used. In this case, for example, a GPC column formed by connecting four columns, "Shodex KF801", "Shodex KF803L", "Shodex KF800L", and "Shodex KF800D" manufactured by Showa Denko K.K., is used. Column temperature can be 40°C. Tetrahydrofuran is used as an eluent, and the measurement is performed at a flow rate of 1.0 ml/min. Usually, a calibration curve is prepared using standard polystyrene, and the weight average molecular weight (Mw) can be obtained in terms of polystyrene.

The (meth)acrylic polymer can be produced by a known method. For example, a (meth)acrylic polymer can be produced by polymerizing a monomer mixture for forming each structural unit using a known polymerization method. The (meth)acrylic polymer may be a partially polymerized product, that is, it may be in a state in which a part of the monomer used for polymerization remains without being polymerized, that is, it may be in the above-mentioned syrup state. In this case, it is clear that the monomers contained in the syrup are part of the monomers used during the polymerization of the (meth)acrylic polymer. As the polymerization method, for example, solution polymerization, bulk polymerization, suspension polymerization, emulsion polymerization, etc. can be adopted. Acrylic polymers can also be obtained from commercial products.

In the adhesive composition, the main agent can be in the form of a syrup (form of a partial polymer of (meth)acrylic polymer) as described above, that is, the main agent is a monofunctional polymer of the (meth)acrylic polymer. It can be a monomer solution. In the case of such a monofunctional monomer solution, the polymer fraction (the content ratio of the polymer to the total mass of the polymer and monofunctional monomer) can be, for example, 1 to 50% by mass, preferably 5 to 50% by mass. It is 30% by mass. The main ingredient may consist only of the above-mentioned (meth)acrylic polymer and the above-mentioned monofunctional monomer.

The type of monofunctional monomer is not particularly limited, and examples thereof include various monomers used to form the above-mentioned (meth)acrylic polymer, such as the above-mentioned (meth)acrylic acid ester, specific Examples include (meth)acrylates having a linear or branched alkyl group, (meth)acrylates having a ring structure in a side chain, and (meth)acrylates having a hydroxyl group in a side chain.

(Silane coupling agent)
Examples of the silane coupling agent include a mercapto silane coupling agent containing a mercapto group, an epoxy silane coupling agent containing an epoxy group, a vinyl silane coupling agent containing a vinyl group, and an isocyanurate silane coupling agent. agents, etc. A commercially available product can also be used as the silane coupling agent. Examples of commercially available products include Shin-Etsu Chemical's KBM-802, X-12-1056ES, KBM-402, KBM-403, KBM-5103, KBM-502, KBM-503, KBM-9659, etc. can. When the pressure-sensitive adhesive composition contains a silane coupling agent, it is possible to further improve the adhesion between the pressure-sensitive adhesive sheet formed from the pressure-sensitive adhesive composition and the adherend.

When the adhesive composition contains a silane coupling agent, the content ratio is not particularly limited. The content ratio of the silane coupling agent is 0.05 parts by mass per 100 parts by mass of the main agent, since peeling between the adherend and the adhesive sheet is unlikely to occur even in a temperature-changing environment or a high-temperature environment. The amount is preferably 0.1 parts by mass or more, more preferably 0.15 parts by mass or more, particularly preferably 0.2 parts by mass or more, and 5 parts by mass or more. It is preferably at most 3 parts by mass, more preferably at most 3 parts by mass, even more preferably at most 2 parts by mass, and particularly preferably at most 1 part by mass.

<Tackifier>
The adhesive composition can further include a tackifier. By including the tackifier in the adhesive composition, the adhesive layer formed from the adhesive composition tends to have better adhesion to the adherend.

The type of tackifier is not particularly limited, and for example, a wide variety of tackifiers used in known pressure-sensitive adhesive sheets can be used.

Among these, the tackifier is preferably an acrylic tackifier. That is, the adhesive composition preferably contains an acrylic tackifier.

Examples of the acrylic tackifier include resins having a glass transition temperature of 20°C or higher. The glass transition temperature of the acrylic tackifier is preferably 30°C or higher, more preferably 40°C or higher, even more preferably 50°C or higher, and preferably 200°C or lower. , more preferably 180°C or lower, and still more preferably 150°C or lower. By setting the glass transition temperature of the acrylic tackifier within the above range, the adhesiveness of the adhesive sheet to the adherend can be improved.

As a structural unit contained in the acrylic tackifier, a monomer unit having an alicyclic ring can be included. When the acrylic tackifier contains a monomer unit having an alicyclic ring, the number of carbon atoms constituting the alicyclic ring is preferably 6 or more. Examples of the alicyclic ring having 6 or more carbon atoms include cyclohexane, cycloheptane, cyclooctane, cyclononane, cyclodecane, cycloundecane, cyclododecane, norbornene, norbornadiene, isobornyl, and dicyclopentane. As the monomer having an alicyclic ring, for example, isobornyl (meth)acrylate, dicyclopentanyl (meth)acrylate, dicyclopentenyl (meth)acrylate, etc. can be preferably used.

The acrylic tackifier can contain an alkyl (meth)acrylate unit instead of the monomer unit having an alicyclic ring or together with the monomer unit having an alicyclic ring. Examples of alkyl (meth)acrylates include methyl (meth)acrylate, ethyl (meth)acrylate, butyl (meth)acrylate, isobutyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, nonyl (meth)acrylate, decyl ( Examples include alkyl (meth)acrylates such as meth)acrylate, lauryl (meth)acrylate, cetyl (meth)acrylate, stearyl (meth)acrylate, and behenyl (meth)acrylate. Among these, the acrylic tackifier preferably contains methyl (meth)acrylate.

The acrylic tackifier is preferably a copolymer containing both a monomer unit having an alicyclic ring and an alkyl (meth)acrylate unit. The content of alkyl (meth)acrylate units based on the total mass of the acrylic tackifier is preferably 5% by mass or more, and 10% by mass, since the adhesion between the adhesive sheet and the adherend is easily improved. It is more preferably at least 90% by mass, and more preferably at most 80% by mass.

The acrylic tackifier may have other monomer units as necessary. Other monomers may be any monomers as long as they are copolymerizable with the above-mentioned alkyl (meth)acrylates, such as (meth)acrylonitrile, vinyl acetate, vinyl chloride, and ethyl vinyl ether. The content of other monomer units in the acrylic tackifier is preferably 10% by mass or less, more preferably 5% by mass or less.

The weight average molecular weight of the tackifier is preferably 3,000 or more, more preferably 3,200 or more, and even more preferably 3,500 or more. The weight average molecular weight of the tackifier may be 20,000 or less, more preferably 15,000 or less, and even more preferably 10,000 or less. The weight average molecular weight of the tackifier is a value measured by gel permeation chromatography (GPC) and converted using a calibration curve prepared using standard polystyrene whose molecular weight is known. As such a resin, a commercially available resin may be used, or one synthesized by a known method may be used.

The content of the tackifier in the adhesive composition is not particularly limited. The content of the tackifier is preferably 1 part by mass or more, and preferably 2 parts by mass or more, based on 100 parts by mass of the base resin, since the adhesiveness of the adhesive sheet to the adherend can be easily improved. It is more preferably 50 parts by mass or less, more preferably 30 parts by mass or less, even more preferably 20 parts by mass or less.

The tackifier may be formed only from an acrylic tackifier, or may contain other components other than the acrylic tackifier. The tackifiers contained in the adhesive composition can be used alone or in combination of two or more.

<Polyfunctional monomer>
The adhesive composition can include a polyfunctional monomer. Examples of such polyfunctional monomers include compounds having two or more polymerizable double bonds in the molecule. The polyfunctional monomer has 2 or more polymerizable double bonds (for example, radically polymerizable double bonds), preferably 2 or more and less than 5, and 2 or more and less than 4. is more preferable. When the adhesive composition contains a polyfunctional monomer, it can react with the monomers in the syrup to form, for example, a crosslinked polymer. That is, when the adhesive composition contains a polyfunctional monomer, the resulting adhesive layer can have a crosslinked structure due to the polyfunctional monomer.

When the adhesive composition contains a polyfunctional monomer, the resulting adhesive sheet is particularly resistant to peeling between the adherend and the adhesive sheet even when placed in a temperature-changing environment or a high-temperature environment.

Examples of polyfunctional monomers include bifunctional monomers (monomers having two polymerizable double bonds) such as polyethylene glycol diacrylate, polypropylene diacrylate, alkyl diacrylate, polytetramethylene glycol diacrylate, Mention may be made of polypropylene glycol diacrylate, dioxane diacrylate, tricyclodecanol diacrylate, and fluorene diacrylate. In addition, as polyfunctional monomers, trimethylolpropane triacrylate or higher functional monomers include alkoxylated trimethylolpropane triacrylate, alkoxylated glycerin triacrylate, caprolactone-modified isocyanurate triacrylate, pentaerythritol acrylate, alkoxylated pentaeryllitol acrylate, (alkoxylated Examples include pentaerythritol acrylate (alkoxylated), ditrimethylolpropane acrylate (alkoxylated), dipentaerythritol acrylate (alkoxylated), and polyglycerin acrylate (ethoxylated).

The polyfunctional monomer may have a bisphenol skeleton in one molecule. Examples of such polyfunctional monomers include diacrylate of bisphenol A diglycidyl ether, diacrylate of propoxylated bisphenol A, diacrylate of bisphenol F diglycidyl ether, and the like.

As the polyfunctional monomer, for example, commercially available products can be used. Commercially available products include "A-200" (polyethylene glycol #200 diacrylate), "A-400" (polyethylene glycol #400 diacrylate), and "NK Ester series, which are bifunctional polyethylene glycol acrylates manufactured by Shin Nakamura Chemical. A-600'' (polyethylene glycol #600 diacrylate), trifunctional monomer A-TMPT ((alkoxylated) totimethylolpropane acrylate), trifunctional monomer M310 (trimethylolpropane PO modified triacrylate) manufactured by Toagosei Co., Ltd. Functional monomer M321 (trimethylolpropane propylene oxide modified triacrylate), bifunctional monomer M211B (bisphenol A EO modified diacrylate) manufactured by Toagosei Co., Ltd., M240 (polyethylene glycol diacrylate), tetrafunctional monomer M-408 (ditrimethylolpropane) tetraacrylate), etc. Other commercially available polyfunctional monomers include A-DOG, A-DCP, A-9300, and A-9200YN manufactured by Shin Nakamura Chemical, FA-731A manufactured by Hitachi Chemical, and AOMA manufactured by Nippon Shokubai. be able to.

In the adhesive composition, the content ratio of the polyfunctional monomer is not particularly limited. The content ratio of the polyfunctional monomer is 0.05 parts by weight per 100 parts by weight of the base resin, since it can make peeling between the adherend and the adhesive sheet particularly difficult even in a temperature changing environment or a high-temperature environment. It is preferably at least 0.1 parts by mass, more preferably at least 0.1 parts by mass, even more preferably at least 0.15 parts by mass, particularly preferably at least 0.2 parts by mass, and It is preferably at most 3 parts by mass, more preferably at most 3 parts by mass, even more preferably at most 2 parts by mass, and particularly preferably at most 1 part by mass. When the content of the polyfunctional monomer is within the above range, it becomes easy to control the residual stress within a desired range 60 seconds after applying 15% torsional shear stress at 105°C.

The polyfunctional monomer contained in the adhesive composition can be used alone or in combination of two or more.

<Additional monofunctional monomer>
The adhesive composition can include additional monofunctional monomers. As mentioned above, when the main ingredient is a syrup (for example, when it is a partially polymerized product), the main ingredient includes a (meth)acrylic polymer and the monomer (monofunctional monomer) used when polymerizing the polymer. In addition to this, the adhesive composition may additionally contain a monofunctional monomer. Therefore, in this specification, "monofunctional monomer" means a monomer derived from a partial polymer of (meth)acrylic polymer, while "additional monofunctional monomer" means a monomer derived from a partial polymer of (meth)acrylic polymer. It can mean monomers other than monomers derived from the partially polymerized product. The additional monofunctional monomer may be of the same type as the monomer derived from the partial polymer of the (meth)acrylic polymer, or may be of a different type.

The type of additional monofunctional monomer is not particularly limited, and for example, a wide range of known monofunctional monomers to which pressure-sensitive adhesive sheets can be applied can be mentioned. Among these, it is preferable that the additional monofunctional monomer has a ring structure. That is, it is preferable that the adhesive composition contains a monofunctional monomer having a ring structure. In this case, the resulting adhesive sheet is likely to be prevented from peeling off from the adherend even if placed in a temperature-changing environment or a high-temperature environment.

The monofunctional monomer having a ring structure is more preferably a (meth)acrylate having a ring structure in its side chain. In the (meth)acrylate having a ring structure in the side chain, the number of carbon atoms in the ring structure is preferably 3 or more, more preferably 4 or more, even more preferably 5 or more, and 6 or more. is even more preferred, preferably 18 or less, more preferably 14 or less, even more preferably 12 or less, particularly preferably 11 or less.

Specific examples of additional monofunctional monomers include cyclohexyl (meth)acrylate, dicyclopentanyl (meth)acrylate, dicyclopentenyloxyethyl (meth)acrylate, isobornyl (meth)acrylate, benzyl (meth)acrylate, phenoxy Examples include ethyl (meth)acrylate, 3-phenoxybenzyl (meth)acrylate, and O-phenylphenoxyethyl (meth)acrylate. Among them, the additional monofunctional monomers include dicyclopentanyl (meth)acrylate and isobornyl (meth)acrylate, since peeling between the adherend and the adhesive sheet is difficult to occur even under a temperature change environment or a high temperature environment. One or more types selected from the group consisting of acrylates are preferred.

The content of the additional monofunctional monomer in the adhesive composition is not particularly limited. The content of the additional monofunctional monomer is preferably 1 part by mass or more, and preferably 2 parts by mass or more, based on 100 parts by mass of the main agent, since the adhesiveness of the adhesive sheet to the adherend is easily improved. is more preferable, more preferably 3 parts by weight or more, particularly preferably 5 parts by weight or more, and preferably 50 parts by weight or less, more preferably 40 parts by weight or less, It is more preferably 30 parts by mass or less, particularly preferably 25 parts by mass or less.

The number of additional monofunctional monomers contained in the pressure-sensitive adhesive composition can be one or more.

<Photopolymerization initiator>
The adhesive composition can further include a photopolymerization initiator. A photopolymerization initiator initiates polymerization of a polyfunctional monomer by irradiation with active energy rays. As used herein, "active energy rays" refer to electromagnetic waves or charged particle beams that have energy quanta, and include ultraviolet rays, electron beams, visible light, X-rays, ion beams, and the like. Among these, from the viewpoint of versatility, ultraviolet rays or electron beams are preferable, and ultraviolet rays are particularly preferable.

The type of photopolymerization initiator is not particularly limited, and for example, a wide range of known photopolymerization initiators can be mentioned. Examples of the photopolymerization initiator include 2,2-dimethoxy-2-phenylacetophenone, 1-hydroxycyclohexyl-phenylketone, 2-hydroxy-2-methyl-1-henylpropanone, and 1-[4-(2-hydroxyethoxyl). -phenyl]-2-hydroxy-methylpropanone, 2-hydroxy-1-(4-(4-(2-hydroxy-2-methylpropionyl)benzyl)phenyl)-2-methyl-1-propanone, and other acetophenones Photopolymerization initiators, acylphosphine oxide photopolymerization initiators such as 2,4,6-trimethylbenzoyl-diphenylphosphine oxide and 2,4,6-trimethylbenzoyl) phenylphosphine oxide, methyl benzoylformate and 4 In addition to intramolecular hydrogen abstraction type photopolymerization initiators such as methylbenzophenone, oil-soluble polymerization initiators such as oxime ester photopolymerization initiators and cationic photopolymerization initiators can be mentioned. Among these, the photopolymerization initiator is preferably at least one selected from the group consisting of an acetophenone photopolymerization initiator, an acylphosphine oxide photopolymerization initiator, and an oxime ester photopolymerization initiator.

A commercially available acetophenone photoinitiator is EsacureOne (oligo(2-hydroxy-2-methyl-1-[4-(1-methylvinyl)phenylpropanone], photoinitiator manufactured by IGM RESINS BV). , Omnirad 651 (2,2-dimethoxy-2-phenylacetophenone, manufactured by IGM RESINS B.V.), Omnirad 184 (1-hydroxycyclohexyl-phenyl ketone, manufactured by IGM RESINS B.V.), Omnirad 1173 (2-hydroxy-2 -Methyl-1-phenylpropanone, manufactured by IGM RESINS B.V.), etc.In addition, as a commercially available acylphosphine oxide photopolymerization initiator, Omnirad 819 (bis(2,4,6- Examples include trimethylbenzoyl) phenylphosphine oxide manufactured by IGM RESINS B.V.) and Omnirad TPO (2,4,6-trimethylbenzoyl-diphenylphosphine oxide manufactured by IGM RESINS B.V.).

In the adhesive composition, the content ratio of the photopolymerization initiator is not particularly limited, and for example, it is preferably 0.01 parts by mass or more, and 0.05 parts by mass or more based on 100 parts by mass of the main agent. is more preferable, more preferably 0.1 parts by mass or more, further preferably 10 parts by mass or less, more preferably 5 parts by mass or less, even more preferably 3 parts by mass or less. , 1.5 parts by mass or less is particularly preferred.

<Adhesive composition>
The adhesive composition contains at least the above-mentioned (meth)acrylic polymer and a silane coupling agent, and, if necessary, a tackifier, a polyfunctional monomer, a monofunctional monomer, and a photopolymerization initiator. It can contain one or more types. The adhesive composition may contain other components as long as the effects of the present invention are not impaired. Other components include crosslinking agents, solvents, plasticizers, antioxidants, metal corrosion inhibitors, ultraviolet absorbers, light stabilizers, and the like. Furthermore, dyes and pigments may be added for the purpose of coloring.

The crosslinking agent can be selected as appropriate, taking into consideration the reactivity with the crosslinkable functional group of the (meth)acrylic polymer, and includes a wide range of known crosslinking agents included in adhesive sheets. . Specific crosslinking agents can be selected from known crosslinking agents such as isocyanate compounds, epoxy compounds, oxazoline compounds, aziridine compounds, metal chelate compounds, and butylated melamine compounds. Among these, the crosslinking agent preferably contains at least one selected from isocyanate compounds, epoxy compounds, and metal chelate compounds.

When the adhesive composition contains a solvent, examples of the solvent include hydrocarbons other than polymerizable monomers such as hexane, heptane, octane, toluene, xylene, ethylbenzene, cyclohexane, and methylcyclohexane; methanol, ethanol, Alcohols such as propanol, isopropyl alcohol, butanol, isobutyl alcohol, and diacetone alcohol; Ethers such as diethyl ether, diisopropyl ether, dioxane, and tetrahydrofuran; Ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone, isophorone, and cyclohexanone; Methyl acetate , ethyl acetate, butyl acetate, isobutyl acetate, amyl acetate, ethyl butyrate and other esters; ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monomethyl ether acetate, propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene Examples include polyols such as glycol monomethyl ether acetate and derivatives thereof.

The adhesive composition is preferably of a solvent-free type. In this case, the adhesive composition preferably contains a polyfunctional monomer. That is, it is preferable that the adhesive composition is a solvent-free type and that the adhesive layer has a crosslinked structure using a polyfunctional monomer. The method for preparing the adhesive composition is not particularly limited, and for example, a wide variety of known methods can be employed.

The adhesive composition is preferably of the so-called active energy ray-curable type, which has the property of being cured by irradiation with active energy rays. In this case, the adhesive composition contains a photopolymerization initiator and components whose polymerization is initiated by the photopolymerization initiator (for example, the aforementioned monofunctional monomer, additional monofunctional monomer, and polyfunctional monomer).

(adhesive sheet)
The adhesive sheet of the present invention is obtained by forming the above-mentioned adhesive composition into a sheet, that is, it includes an adhesive layer containing a cured product of the adhesive composition.

The adhesive layer can be formed by curing the adhesive composition. The method of curing the adhesive composition is not particularly limited, and for example, a wide variety of known methods can be employed. Specifically, the method may include a step of coating the adhesive composition on a substrate to form a coating film, and a step of irradiating the coating film with active energy rays to obtain a cured adhesive. can. As a result, a pressure-sensitive adhesive layer formed by curing the pressure-sensitive adhesive can be formed.

Coating of the adhesive composition can be carried out using a known coating device. Examples of the coating device include a blade coater, an air knife coater, a roll coater, a bar coater, a gravure coater, a microgravure coater, a rod blade coater, a lip coater, a die coater, and a curtain coater.

The base material used for coating the adhesive composition is not particularly limited. For example, the adhesive composition can be applied to various base materials such as resin base materials and glass base materials. When the base material has a release sheet described below, the adhesive composition can also be coated on this release sheet. Moreover, the adhesive composition can also be directly applied onto the member to be bonded. The thickness of the adhesive composition after coating is also not particularly limited, and can be appropriately set depending on the desired thickness of the adhesive layer (or adhesive sheet). After forming the coating film, the coating film may be subjected to heat treatment or drying treatment, if necessary.

For the step of irradiating the coating film with active energy rays, for example, a step similar to a known method can be adopted. In such a process, the photopolymerization initiator in the adhesive composition generates radicals by active energy rays, and the polymerizable components in the adhesive composition (for example, the monomers in the adhesive composition, Polyfunctional monomers, etc.) initiate and proceed with a polymerization reaction by the generated radicals, resulting in a polymerized and cured product. This forms an adhesive layer and also improves adhesive strength.

Examples of active energy rays include ultraviolet rays, electron beams, visible rays, X-rays, and ion beams, and can be appropriately selected depending on the photopolymerization initiator contained in the adhesive composition. Among these, from the viewpoint of versatility, ultraviolet rays or electron beams are preferable, and ultraviolet rays are particularly preferable. As the ultraviolet light source, for example, a chemical lamp, a high-pressure mercury lamp, a low-pressure mercury lamp, an ultra-high-pressure mercury lamp, a metal halide lamp, a carbon arc, a xenon arc, an electrodeless ultraviolet lamp, etc. can be used. The irradiation output of ultraviolet rays is preferably such that the cumulative light amount is 100 to 10,000 mJ/cm ² , more preferably 200 to 5,000 mJ/cm ² . In the step of irradiating the coating film with active energy rays, the active energy rays may be irradiated in two stages.

The cured product formed as described above can be used as the adhesive layer of the adhesive sheet of the present invention. The adhesive layer may consist only of a cured adhesive, or may contain other components in addition to the cured adhesive.

As long as the adhesive sheet of the present invention includes the above-mentioned adhesive layer, it can also include other layers, or it may be formed only of the adhesive layer. That is, it is preferable that the adhesive sheet consists of only the adhesive layer. The adhesive layer has, for example, a single layer structure.

The gel fraction of the adhesive layer is 80% or more. When the gel fraction of the adhesive layer is less than 80%, peeling between the adherend and the adhesive sheet is likely to occur when placed in a temperature-changing environment or a high-temperature environment. The gel fraction of the adhesive layer is preferably 82% or more, more preferably 84% or more, and preferably 98% or less, more preferably 95% or less.

The gel fraction of the adhesive layer is a value measured by the following method. First, about 0.1 g of the adhesive sheet (adhesive layer) is taken into a sample bottle, 30 ml of ethyl acetate is added thereto, and the mixture is shaken for 24 hours. Thereafter, the contents of this sample bottle are filtered through a 200-mesh stainless steel wire mesh, and the residue on the wire mesh is dried at 120° C. for 1 hour, and the dry mass (g) is measured. From the obtained dry mass, the following formula gel fraction (mass%) = (dry mass/collected mass of adhesive sheet) x 100...Formula 1
1 to determine the gel fraction.

The adhesive layer has a residual stress of 3.0 kPa or more and 10.0 kPa or less after 60 seconds after applying 15% torsional shear stress at 105°C. Hereinafter, the residual stress 60 seconds after applying 15% torsional shear stress at 105° C. will be simply referred to as "60 seconds residual stress."

If the residual stress of the adhesive layer after 60 seconds is less than 3.0 kPa or exceeds 10.0 kPa, the bond between the adherend and the adhesive sheet when placed in a temperature change environment or high temperature environment. Peeling is more likely to occur. The residual stress of the adhesive layer after 60 seconds is preferably 3.5 kPa or more, preferably 9 kPa or less, more preferably 8 kPa or less, and even more preferably 7 kPa or less.

The residual stress of the adhesive layer after 60 seconds can be measured using a laminated sheet of adhesive layers laminated to have a thickness of 1000 μm. Specifically, the laminated sheet is pressurized in an autoclave at 30° C. and in an atmosphere of 0.5 MPa for 10 minutes to obtain a measurement sample. The obtained measurement sample was kept constant at an initial heating temperature of 105°C for 2 minutes using an Anton Paar MCR301 with a probe diameter of 8 mm, and then a torsional strain of 15% was applied while keeping the temperature at 105°C. , read the shear stress one minute after loading. This shear stress is defined as the residual stress of the adhesive layer after 60 seconds.

The thickness of the adhesive layer is preferably 75 μm or more. In this case, peeling between the adherend and the pressure-sensitive adhesive sheet tends to be difficult to occur even under a high temperature change environment or a hot environment. The thickness of the adhesive layer is more preferably 80 μm or more, even more preferably 90 μm or more, particularly preferably 100 μm or more, and preferably 1000 μm or less, and 500 μm or less. The thickness is more preferably 400 μm or less.

The adhesive sheet of the present invention can also be an adhesive sheet provided with a base material such as a release sheet on one or both sides. That is, the present invention also includes a pressure-sensitive adhesive sheet with a release sheet, which includes a pressure-sensitive adhesive sheet and a release sheet.

As a release sheet, a release laminate sheet having a release sheet base material and a release agent layer provided on one side of this release sheet base material, or a polyolefin film such as a polyethylene film or a polypropylene film as a low polarity base material. Can be mentioned. Paper or polymer film is used as the base material for the release sheet in the release laminate sheet. As the release agent constituting the release agent layer, for example, a general-purpose addition type or condensation type silicone release agent or a long-chain alkyl group-containing compound is used. A commercially available product may be used as the peelable laminate sheet. Examples include a heavy separator film that is a release-treated polyethylene terephthalate film manufactured by Teijin DuPont Films, and a light separator film that is a release-treated polyethylene terephthalate film manufactured by Teijin DuPont Films.

The adhesive sheet of the present invention is used for bonding a pair of adherends having different expansion and contraction ratios. Here, when one of the pair of adherends is referred to as adherend A and the other as adherend B, the following formula (1)
|(X1-X2)|≧0.1%...(1)
satisfy. In formula (1), X1 is the expansion/contraction rate (%) when adherend A is heated from 23°C to 110°C, and X2 is the expansion/contraction rate (%) when adherend B is heated from 23°C to 110°C. ). When the expansion/contraction rate is x, x is {(length of adherend at 110°C - length of adherend at 23°C before heating)/length of adherend at 23°C before heating} x 100 (%)
This is the value calculated by The length of the adherend is, for example, the length of the adherend in the MD direction or the TD direction.

In addition, in Formula (1), there may be a directionality of the expansion/contraction rate in the adherend A and the adherend B (the expansion/contraction rate may differ depending on the direction). In such a case, the expansion and contraction ratios in the direction in which the rate of change in expansion and contraction ratio when heated from 23° C. to 110° C. is large are used as the values of X1 and X2, respectively.

By bonding adherend A and adherend B that satisfy formula (1) with the adhesive sheet of the present invention, the adherend and adhesive sheet can be separated even under a temperature change environment or a high temperature environment. This tends to make it difficult for this to occur.

In formula (1), |(X1-X2)| is preferably ≧0.1%, more preferably |(X1-X2)|≧0.15%, |(X1-X2)| More preferably, it is ≧0.2%. Further, the upper limit of |(X1−X2)| is preferably 1%.

Of the adherends A and B, the adherend with a higher expansion/contraction rate when heated from 23° C. to 110° C. preferably has a thickness of 2 mm or more. In this case, the adhesive sheet of the present invention can also be suitably used for applications such as automobile sunroofs and large windows of buildings. The thickness of the adherend A and the adherend B can be, for example, 100 mm or less.

It is preferable that both the adherend A and the adherend B have a total light transmittance of 50% or more. In this case, the adhesive sheet of the present invention is suitable for applications requiring high transparency, and can be particularly suitably used for applications such as automobile sunroofs and large windows of buildings.

The combination of materials for the adherend A and the adherend B is not particularly limited, and various combinations can be mentioned as long as the above formula (1) is satisfied. For example, if the adherend with a larger expansion/contraction rate (%) when heated from 23°C to 110°C is polycarbonate, the adherend with a smaller expansion/contraction rate (%) when heated from 23°C to 110°C is polycarbonate. Examples of the adherend include glass, stretched polyethylene terephthalate, cycloolefin polymer film, TAC film, and ITO-deposited film.

The adhesive sheet of the present invention can be used for various purposes for bonding adherends together, and is particularly suitable for car windows and sunroofs, building material windows, and door windows. In particular, the adhesive sheet of the present invention is difficult to peel off between the adherend and the adhesive sheet even when placed in a temperature-changing environment or a high-temperature environment. It can be suitably used for purposes such as.

The adhesive sheet of the present invention can form a laminate by bonding adherends together. That is, the present invention includes a laminate including the above-mentioned adhesive sheet and a pair of adherends having different expansion and contraction ratios.

One embodiment of the laminate is a laminate in which the adherend A, the adhesive sheet of the present invention, and the adherend B are laminated in this order. In this case, the adhesive sheet of the present invention is directly bonded to the adherends A and B.

Since the above-mentioned laminate includes the adhesive sheet of the present invention, it adheres well even under a temperature change environment and a high temperature environment, even though the expansion and contraction rates of adherend A and adherend B are different from each other. Peeling between the body and the adhesive sheet is less likely to occur. For example, even if the adherend with a larger expansion/contraction ratio has a thickness exceeding 2 mm, the adhesive sheet in the laminate is unlikely to peel off.

In specifying the invention encompassed by the present disclosure, each configuration (property, structure, function, etc.) described in each embodiment of the present disclosure may be combined in any manner. That is, the present disclosure includes all subject matter consisting of all combinations of the combinable structures described in this specification.

EXAMPLES Hereinafter, the present invention will be explained in more detail with reference to Examples, but the present invention is not limited to the embodiments of these Examples.

The following monomers (monofunctional monomers) for producing the "base material containing (meth)acrylic polymer" used in each example were prepared.
・2EHA: 2-ethylhexyl acrylate ・BA: butyl acrylate ・4HBA: 4-hydroxybutyl acrylate ・IBXA: isobornyl acrylate ・CHMA: cyclohexyl methacrylate

In addition, the following were prepared as the "polyfunctional monomer", "additional monofunctional monomer", "silane coupling agent", and "photopolymerization initiator" used in each example.

(polyfunctional monomer)
・A-200: Bifunctional monomer (polyethylene glycol #200 diacrylate, manufactured by Shin Nakamura Chemical Co., Ltd., NK Ester A-200 (registered trademark))
・A-600: Bifunctional monomer (polyethylene glycol #200 diacrylate, manufactured by Shin Nakamura Chemical Co., Ltd., NK Ester A-600 (registered trademark))

(Additional monofunctional monomer)
・IBXA: Isobornyl acrylate (manufactured by Osaka Organic Chemical Industry)
・DCPA: Dicyclopentanyl acrylate (manufactured by Resonac)

(Silane coupling agent)
・KBM-9659 (“KBM-9659” (registered trademark) manufactured by Shin-Etsu Chemical Co., Ltd.)
・KBM-403 (“KBM-403” (registered trademark) manufactured by Shin-Etsu Chemical Co., Ltd.)

(Photopolymerization initiator)
・Esacure One (registered trademark) (manufactured by IGM Resins B.V., Esacure One (registered trademark))

(Production Example 1: Production of tackifier a)
250 g of methyl methacrylate, 250 g of isobornyl methacrylate, 20 g of n-dodecyl mercaptan, 500 g of ethyl acetate, and 200 g of methyl ethyl ketone were placed in a 2 L flask equipped with a stirrer, nitrogen inlet tube, cooling tube, and thermometer, and the mixture was heated at a nitrogen flow rate of 300 ml/min for 60 g. After purging with nitrogen for a minute, the nitrogen flow rate was lowered to 100 ml/min, the temperature was raised to 70° C. in a water bath, and heating was stopped. 2 g of AIBN was added and reacted for 3 hours while controlling heat generation, and then 3 g of AIBN was added and reacted for 4 hours, and then cooled to 30°C. Finally, by drying at 100°C for 5 hours to remove the solvent, an acrylic tackifier a (denoted as tackifying resin a in Table 1) with a weight average molecular weight of 6,000 and a glass transition temperature of 85°C I got it.

(Production Example 2: Production of tackifier b)
Acrylic tackifier b with a weight average molecular weight of 8,000 and a glass transition temperature of 95°C was prepared in the same manner as in Production Example 1 except that 200 g of methyl methacrylate, 300 g of isobornyl methacrylate, and 15 g of n-dodecyl mercaptan were used. (denoted as tackifying resin b in Table 1) was obtained.

(Production Example 3: Production of tackifier c)
An acrylic tackifier c (with a weight average molecular weight of 6,000 and a glass transition temperature of 95°C) was prepared in the same manner as in Production Example 1 except that 250 g of dicyclopentanyl methacrylate was used instead of 250 g of isobornyl methacrylate. In Table 1, a tackifying resin (denoted as c) was obtained.

The tackifiers obtained in Production Examples 1 to 3 were previously dried at 100° C. for 5 hours to remove the solvent before use in each Example.

(Example 1)
<Production of main ingredient containing (meth)acrylic polymer>
A (meth)acrylic polymer (syrup) was synthesized according to the main ingredient composition containing the (meth)acrylic polymer shown in Table 1. Specifically, 100 parts by mass of a mixed monomer consisting of 2EHA, 4HBA, and IBXA (mass ratio 65:30:5) prepared in the amounts shown in Table 1, and 0.06 parts by mass of n-dodecylmercaptan. The mixture was placed in a 2 L flask equipped with a stirrer, a nitrogen inlet tube, a cooling tube, and a thermometer, and the mixture was purged with nitrogen for 60 minutes at a nitrogen flow rate of 300 ml/min. Thereafter, the nitrogen flow rate was lowered to 100 ml/min, the temperature was raised to 65° C. in a water bath, 0.15 g of AIBN was added, the reaction was allowed to occur for 30 minutes while controlling the heat generation, and then the mixture was cooled to room temperature. Additional monomers were added to the flask so that the monomer ratio by mass was as described above, and the solid content concentration was adjusted to 20%. As described above, a (meth)acrylic polymer syrup (a solution of a (meth)acrylic polymer dissolved in a monofunctional monomer) having a solid content concentration of 20% by mass and a weight average molecular weight of 900,000 was obtained as a main ingredient.

<Manufacture of adhesive composition>
Next, an adhesive layer was obtained from an adhesive composition prepared according to the adhesive composition preparation conditions shown in Table 1. First, as shown in Table 1, 6 parts by mass of the tackifier a (tackifying resin a) obtained in Production Example 1 and 0% A-200 as a polyfunctional monomer were added to 100 parts by mass of the total amount of the base resin. .2 parts by mass, 5 parts by mass of IBXA as an additional monofunctional monomer (denoted as "monofunctional monomer" in Table 1), 0.3 parts by mass of KBM-9659 as a silane coupling agent, and a photopolymerization initiator. 0.3 parts by mass of Esacure One was added thereto, and stirring and defoaming were performed to obtain adhesive composition 1.

<Manufacture of adhesive sheet>
The obtained adhesive composition 1 was applied to a thickness of 300 μm on a 100 μm thick polyester film (release sheet) coated with a silicone mold release agent, and a 75 μm thick polyester film coated with a silicone mold release agent was applied. After laminating with a polyester film (release sheet), it was irradiated with a chemical lamp at an illuminance of 5 mW/cm ² and a cumulative illuminance of 750 mJ/cm ² , and then a high-pressure mercury lamp was irradiated with an illuminance of 200 mW/cm ² and a cumulative illuminance of 2000 mJ/cm ^{2 .} A pressure-sensitive adhesive layer was formed by irradiation so that the pressure-sensitive adhesive sheet 1 having release sheets on both sides was obtained.

<Preparation of laminate>
Adherent A is a 5 mm thick polycarbonate plate cut into 15 cm squares (PC-1600 manufactured by Takiron C.I.); adherend B is a 1 mm thick float glass cut into 15 cm squares (manufactured by Hiraoka Glass Industries). Got ready. The adherend A was previously annealed by placing it in a dryer at 95° C. for 6 hours, and then one side of the annealed adherend A was subjected to corona treatment. Such corona treatment was performed using CORONA GENERATOR AGF-B10 (manufactured by Kasuga Denki) at an output of 0.14 kW, a speed of 5 m/min, and the number of treatments was 4 times. Next, one of the polyester films bonded to the adhesive sheet 1 was peeled off, and the corona-treated surface of the adherend A was bonded to the exposed adhesive layer. Thereafter, the other polyester film of the adhesive sheet was peeled off, and adherend B was bonded to the exposed adhesive layer to obtain a laminate. This laminate was pressure-bonded in an autoclave at a pressure of 0.5 kPa and a temperature of 30° C. for 30 minutes, and then allowed to stand at room temperature for one day to produce a laminate for evaluation.

(Example 2)
<Production of main ingredient containing (meth)acrylic polymer>
A syrup of meth)acrylic polymer was obtained as the main ingredient in the same manner as in the production of the (meth)acrylic polymer in Example 1, except that the main ingredient composition was changed to the conditions shown in Table 1.

<Manufacture of adhesive composition>
Adhesive composition 2 was obtained in the same manner as in the production of the adhesive composition in Example 1, except that the conditions for preparing the adhesive composition were changed to those shown in Table 1.

<Manufacture of adhesive sheet>
Adhesive sheet 2 was obtained in the same manner as in the production of the adhesive sheet in Example 1, except that adhesive composition 2 was applied in place of adhesive composition 1 to a thickness of 175 μm.

<Preparation of laminate>
A laminate was obtained in the same manner as in Example 1 except that adhesive sheet 1 was changed to adhesive sheet 2 and adherend A was changed to a polycarbonate plate having a thickness of 3 mm.

(Example 3)
<Production of (meth)acrylic polymer>
A syrup of meth)acrylic polymer was obtained as the main ingredient in the same manner as in the production of the (meth)acrylic polymer in Example 1, except that the main ingredient composition was changed to the conditions shown in Table 1.

<Manufacture of adhesive composition>
Adhesive composition 3 was obtained in the same manner as in the production of the adhesive composition in Example 1, except that the conditions for preparing the adhesive composition were changed to those shown in Table 1.

<Manufacture of adhesive sheet>
Adhesive sheet 3 was obtained in the same manner as in the production of the adhesive sheet in Example 1, except that adhesive composition 3 was applied in place of adhesive composition 1 to a thickness of 250 μm.

<Preparation of laminate>
A laminate was obtained in the same manner as in the production of the laminate in Example 1, except that adhesive sheet 1 was replaced with adhesive sheet 3.

(Example 4)
<Production of (meth)acrylic polymer>
A syrup of meth)acrylic polymer was obtained as the main ingredient in the same manner as in the production of the (meth)acrylic polymer in Example 1, except that the main ingredient composition was changed to the conditions shown in Table 1.

<Manufacture of adhesive composition>
Adhesive composition 4 was obtained in the same manner as in the production of the adhesive composition in Example 1, except that the conditions for preparing the adhesive composition were changed to those shown in Table 1.

<Manufacture of adhesive sheet>
Adhesive sheet 4 was obtained in the same manner as in the production of the adhesive sheet in Example 1, except that the obtained adhesive composition 4 was used instead of adhesive composition 1.

<Preparation of laminate>
Adhesive sheet 1 was changed to adhesive sheet 4, adherend A was changed to a polycarbonate plate with a thickness of 3 mm, and adherend B was a polyethylene terephthalate film with a thickness of 0.1 mm ("A4360" manufactured by Toyobo). A laminate was obtained in the same manner as the laminate of Example 1 except that the following was changed. In preparing this laminate, the polyethylene terephthalate film was pasted together so that its easily adhesive surface was in contact with the adhesive sheet (adhesive layer).

(Example 5)
<Production of (meth)acrylic polymer>
A syrup of meth)acrylic polymer was obtained as the main ingredient in the same manner as in the production of the (meth)acrylic polymer in Example 1, except that the main ingredient composition was changed to the conditions shown in Table 1.

<Manufacture of adhesive composition>
Adhesive composition 5 was obtained in the same manner as in the production of the adhesive composition in Example 1, except that the conditions for preparing the adhesive composition were changed to those shown in Table 1.

<Manufacture of adhesive sheet>
Adhesive sheet 5 was obtained in the same manner as in the production of the adhesive sheet in Example 1, except that adhesive composition 5 was applied to a thickness of 100 μm instead of adhesive composition 1.

<Preparation of laminate>
Adhesive sheet 1 was changed to adhesive sheet 5, adherend A was changed to a polycarbonate plate (manufactured by Mitsubishi Gas Chemical, MRS58TB) with a thickness of 2 mm, and adherend B was changed to a heat shielding plate with a thickness of 0.05 mm. A laminate was obtained in the same manner as in Example 1, except that the film was changed to a film ("ITO vapor deposited film" manufactured by Geomatec). In addition, in producing this laminate, the heat shielding film was bonded together so that the ITO surface of the film was in contact with the adhesive sheet (adhesive layer).

(Example 6)
<Production of (meth)acrylic polymer>
A syrup of meth)acrylic polymer was obtained as the main ingredient in the same manner as in the production of the (meth)acrylic polymer in Example 1, except that the main ingredient composition was changed to the conditions shown in Table 1.

<Manufacture of adhesive composition>
Adhesive composition 6 was obtained in the same manner as in the production of the adhesive composition in Example 1, except that the conditions for preparing the adhesive composition were changed to those shown in Table 1.

<Manufacture of adhesive sheet>
Adhesive sheet 6 was obtained in the same manner as in the production of the adhesive sheet in Example 1, except that adhesive composition 6 was applied in place of adhesive composition 1 to a thickness of 150 μm.

<Preparation of laminate>
The method was the same as that for producing the laminate in Example 1, except that adhesive sheet 1 was changed to adhesive sheet 6, and adherend A was changed to a polycarbonate plate with a thickness of 1 mm ("PC1151" manufactured by Teijin). A laminate was obtained.

(Example 7)
<Production of (meth)acrylic polymer>
A syrup of meth)acrylic polymer was obtained as the main ingredient in the same manner as in the production of the (meth)acrylic polymer in Example 1, except that the main ingredient composition was changed to the conditions shown in Table 1.

<Manufacture of adhesive composition>
Adhesive composition 7 was obtained in the same manner as in the production of the adhesive composition in Example 1, except that the conditions for preparing the adhesive composition were changed to those shown in Table 1.

<Manufacture of adhesive sheet>
Adhesive composition 7 was applied to a thickness of 50 μm instead of adhesive composition 1, and silicone release agent was applied instead of a 75 μm thick polyester film (release sheet) coated with a silicone release agent. Adhesive sheet 7 was obtained in the same manner as in the production of the adhesive sheet in Example 1, except that a 50 μm thick polyester film (release sheet) coated with a molding agent was used.

<Preparation of laminate>
The process was the same as the production of the laminate in Example 1, except that the adhesive sheet 1 was changed to the adhesive sheet 7, and the adherend A was changed to a polycarbonate plate (manufactured by Mitsubishi Gas Chemical, MRS58TB) with a thickness of 2 mm. A laminate was obtained by the method.

(Comparative example 1)
<Production of (meth)acrylic polymer>
A syrup of meth)acrylic polymer was obtained as the main ingredient in the same manner as in the production of the (meth)acrylic polymer in Example 1, except that the main ingredient composition was changed to the conditions shown in Table 1.

<Manufacture of adhesive composition>
A pressure-sensitive adhesive composition 1a was obtained in the same manner as in the production of the pressure-sensitive adhesive composition in Example 1, except that the pressure-sensitive adhesive composition preparation conditions were changed to those shown in Table 1.

<Manufacture of adhesive sheet>
A pressure-sensitive adhesive sheet 1a was obtained in the same manner as in the production of the pressure-sensitive adhesive sheet in Example 1, except that pressure-sensitive adhesive composition 1a was applied in place of pressure-sensitive adhesive composition 1 to a thickness of 250 μm.

<Preparation of laminate>
A laminate was obtained in the same manner as in the production of the laminate in Example 1, except that adhesive sheet 1 was replaced with adhesive sheet 1a.

(Comparative example 2)
<Production of (meth)acrylic polymer>
A syrup of meth)acrylic polymer was obtained as the main ingredient in the same manner as in the production of the (meth)acrylic polymer in Example 1, except that the main ingredient composition was changed to the conditions shown in Table 1.

<Manufacture of adhesive composition>
Adhesive composition 2a was obtained in the same manner as in the production of the adhesive composition in Example 1, except that the conditions for preparing the adhesive composition were changed to those shown in Table 1.

<Manufacture of adhesive sheet>
A pressure-sensitive adhesive sheet 2a was obtained in the same manner as in the production of the pressure-sensitive adhesive sheet in Example 1, except that the obtained pressure-sensitive adhesive composition 2a was used instead of pressure-sensitive adhesive composition 1.

<Preparation of laminate>
The preparation of the laminate was the same as in Example 1 except that the adhesive sheet 1 was changed to the adhesive sheet 2a and the adherend B was changed to a polyethylene terephthalate film (manufactured by Toyobo "A4360") with a thickness of 0.1 mm. A laminate was obtained using the method described above. In preparing this laminate, the polyethylene terephthalate film was pasted together so that its easily adhesive surface was in contact with the adhesive sheet (adhesive layer).

(Comparative example 3)
<Production of (meth)acrylic polymer>
A syrup of meth)acrylic polymer was obtained as the main ingredient in the same manner as in the production of the (meth)acrylic polymer in Example 1, except that the main ingredient composition was changed to the conditions shown in Table 1.

<Manufacture of adhesive composition>
Adhesive composition 3a was obtained in the same manner as in the production of the adhesive composition in Example 1, except that the conditions for preparing the adhesive composition were changed to those shown in Table 1.

<Manufacture of adhesive sheet>
A pressure-sensitive adhesive sheet 3a was obtained in the same manner as in the production of the pressure-sensitive adhesive sheet in Example 1, except that the pressure-sensitive adhesive composition 3a was applied to a thickness of 175 μm instead of pressure-sensitive adhesive composition 1.

<Preparation of laminate>
A laminate was obtained in the same manner as in Example 1 except that the adhesive sheet 1 was changed to an adhesive sheet 3a and the adherend A was changed to a polycarbonate plate having a thickness of 3 mm.

Evaluation method (Tg of tackifier)
DSC600 manufactured by Hitachi High-Tech Science was used to measure the glass transition temperature of the tackifier. The reference is 5 mg of alumina, and about 5 mg of the solvent-free tackifying resin is placed in a sample aluminum pan with a diameter of 5 mm, and the temperature is raised from 0 to 150 °C at a temperature increase rate of 10 °C/min in an environment with a nitrogen flow rate of 50 ml/min. The temperature was raised. At that time, the inflection point at which the specific heat changed was read as the glass transition temperature of the tackifying resin.

(gel fraction)
Approximately 0.1 g of the adhesive sheet (adhesive layer) was collected in a sample bottle, 30 ml of ethyl acetate was added, and the sample bottle was shaken for 24 hours.The contents of the sample bottle were then filtered through a 200 mesh stainless steel wire mesh. The above residue was dried at 120° C. for 1 hour, and the dry mass (g) was measured. From the obtained dry mass, the following formula gel fraction (mass%) = (dry mass/collected mass of adhesive sheet) x 100...Formula 1
The gel fraction was determined using 1.

<Residual stress after 60 seconds>
First, a laminated sheet having a thickness of 1000 μm was produced by laminating a plurality of adhesive layers formed from each adhesive composition. Next, the laminated sheet was pressurized in an autoclave at 30° C. and in an atmosphere of 0.5 MPa for 10 minutes to obtain a measurement sample. The obtained measurement sample was kept constant at an initial heating temperature of 105°C for 2 minutes using an Anton Paar MCR301 with a probe diameter of 8 mm, and then a torsional strain of 15% was applied while keeping the temperature at 105°C. The shear stress was read one minute after loading. This shear stress was defined as the residual stress of the adhesive layer after 60 seconds. Note that the residual stress after 60 seconds means the residual stress 60 seconds after applying 15% torsional shear stress at 105°C.

<Measurement of expansion/contraction rate of adherend>
To measure the expansion and contraction rates of adherend A and adherend B, TMA7100 manufactured by Hitachi High-Tech Science was used. The adherend was left standing in an environment with a nitrogen flow rate of 200 ml/min, and the temperature was raised from 23°C to 150°C at a temperature increase rate of 20°C/min. At this time, the expansion/contraction rate was read when the sample temperature reached 110° C., and this was defined as the expansion/contraction rate (X1 and X2) of the adherend. For adherends with a thickness exceeding 1 mm, a sample side of 1 cm square was prepared and the measurement was performed in compression mode, and for the film, it was cut into 5 mm x 40 mm and then measured in tension mode.

<High temperature-low temperature cycle test>
The laminates produced in Examples and Comparative Examples were left standing in a thermal shock tester ES-57L manufactured by Hitachi Air Conditioning SE. The atmospheric temperature in this test area was changed from -20°C to 85°C, and then changed again to -20°C, and this was regarded as one cycle, and the temperature was repeatedly changed. The time per cycle was set to 1 hour, and the test was terminated after 72 hours had elapsed. After the test, the laminate was visually checked and evaluated using the following criteria.
≪Judgment criteria≫
Good: Peeling from the edge was less than 2 mm, no bubbles were generated, and peeling was extremely easily suppressed even when temperature changed.
Δ: Peeling from the end portion was 2 mm or more and less than 5 mm, and no bubbles were generated, and peeling was easily suppressed even if a temperature change occurred.
×: Peeling from the end portion was 5 mm or more or generation of bubbles was confirmed, and peeling was likely to occur due to temperature change.

<Boiling test>
The laminates produced in Examples and Comparative Examples were placed in a boiling water bath, held in this state for 2 hours, then taken out, visually checked, and evaluated using the following criteria.
Good: Peeling from the edge was less than 2 mm, and no bubbles were generated, and peeling between the adherend and the adhesive sheet was extremely difficult to occur even in a high-temperature environment.
Δ: Peeling from the edge was 2 mm or more and less than 5 mm, and no bubbles were generated, and peeling between the adherend and the adhesive sheet was difficult to occur even in a high-temperature environment.
×: Peeling from the edge was 5 mm or more or generation of bubbles was confirmed, and peeling was likely to occur in a high-temperature environment.

Evaluation results Table 1 shows the (meth)acrylic polymer composition, pressure-sensitive adhesive composition preparation conditions, and the thickness of the obtained pressure-sensitive adhesive sheets in producing the pressure-sensitive adhesive sheets obtained in each example and comparative example. The measurement results of gel fraction and residual stress after 60 seconds (residual stress after 60 seconds after applying 15% torsional shear stress at 105° C.) are shown.

Table 1 also shows the evaluation results of the laminates obtained using the adhesive sheets obtained in each Example and Comparative Example, Adherent A and Adherent B (high temperature-low temperature cycle test and boiling test). results). Table 1 also shows the expansion/contraction rate (2%) and thickness of adherends A and B when heated from 23°C to 110°C, as well as the value of |(X1-X2)| in equation (1). It shows. In addition, X1 indicates the expansion/contraction rate (%) of adherend A when heated from 23°C to 110°C, and X2 indicates the expansion/contraction rate (%) of adherend B when heated from 23°C to 110°C. .

In addition, in the preparation conditions of the adhesive composition in Table 1, a blank column means that the raw material is not used.

From Table 1, it can be seen that the adhesive sheets obtained in Examples do not easily peel off even when subjected to temperature changes, even when adherends with different expansion and contraction ratios are bonded together, and they do not peel easily when placed in a high-temperature environment. The adhesion between the adherend and the pressure-sensitive adhesive sheet was also good, and peeling of the pressure-sensitive adhesive sheet was difficult to occur, and peeling at the edges was particularly easily suppressed. Therefore, when the pressure-sensitive adhesive layer is obtained from the pressure-sensitive adhesive composition containing at least a (meth)acrylic polymer and a silane coupling agent, the gel fraction of the pressure-sensitive adhesive layer and the residual stress after 60 seconds are It has been demonstrated that within a predetermined range, a pressure-sensitive adhesive sheet can be obtained that is difficult to peel off even under temperature changes and high-temperature environments.

Claims (10)

An adhesive sheet used for bonding a pair of adherends having different expansion and contraction ratios,
comprising an adhesive layer obtained from an adhesive composition,
The adhesive composition contains at least a base agent containing a (meth)acrylic polymer and a silane coupling agent,
The (meth)acrylic polymer is a polymer of monomers including (meth)acrylate having a linear or branched alkyl group, (meth)acrylate having a ring structure in the side chain, and (meth)acrylate having a hydroxyl group in the side chain. It is a combination,
The adhesive layer has a crosslinked structure with a polyfunctional monomer, and the polyfunctional monomer is a compound having two or more polymerizable double bonds in the molecule,
The adhesive layer has a gel fraction of 80% or more,
The adhesive layer has a residual stress of 3.0 kPa or more and 10.0 kPa or less after 60 seconds after applying 15% torsional shear stress at 105 ° C.,
The following formula (1)
|(X1-X2)|≧0.1%...(1)
(Here, when one of the pair of adherends is referred to as adherend A and the other as adherend B, X1 is the expansion/contraction rate (%) when adherend A is heated from 23°C to 110°C. , X2 is the expansion/contraction rate (%) when adherend B is heated from 23°C to 110°C)
Adhesive sheet that meets the requirements. The adhesive sheet according to claim 1, wherein the adhesive composition contains a monofunctional monomer having a ring structure. The adhesive sheet according to claim 1 or 2, wherein the adhesive composition contains the silane coupling agent in an amount of 0.05 parts by mass or more and 5 parts by mass or less based on 100 parts by mass of the main agent. The adhesive sheet according to claim 1 or 2, wherein the adhesive composition is a solvent-free type. The adhesive sheet according to claim 1 or 2, wherein the adhesive composition contains an acrylic tackifier. The adhesive sheet according to claim 1 or 2, having a thickness of 75 μm or more. The adhesive sheet according to claim 1 or 2, wherein the adherend having a higher expansion/contraction rate among the adherend A and the adherend B has a thickness of 2 mm or more. The adhesive sheet according to claim 1 or 2, wherein both the adherend A and the adherend B have a total light transmittance of 50% or more. The adhesive sheet according to claim 8, which is used for car windows, building material windows, or door windows. A laminate comprising the adhesive sheet according to claim 1 or 2 and a pair of adherends having different expansion and contraction rates.