JP7447565B2 - Adhesive compositions, adhesives, adhesive sheets and laminates - Google Patents

Description

The present invention relates to a pressure-sensitive adhesive composition that has tackiness under normal conditions and develops adhesiveness when cured by heating, etc., and more specifically, relates to a pressure-sensitive adhesive composition that has tackiness under normal conditions and develops adhesiveness when cured by heating. The present invention relates to a pressure-sensitive adhesive composition that forms a pressure-sensitive adhesive having excellent reworkability and excellent adhesiveness to adherends. Further, the present invention provides an adhesive sheet having an adhesive layer containing the above-mentioned adhesive, and an adherend in which the adhesive layer containing the above-mentioned adhesive is laminated. This relates to a laminate.

Conventionally, liquid adhesives using epoxy compounds have been used to bond metals and plastics. Recently, there has also been an increasing demand for pressure-sensitive adhesives that have both the properties of adhesives and adhesives, such as being sticky under normal conditions and curing by heating to form a strong bond after being applied to the adherend. As such an adhesive, a thermosetting pressure-sensitive adhesive composition using an acrylic resin, an epoxy resin, and an epoxy curing agent has been proposed (see, for example, Patent Document 1).

Furthermore, in recent years, excellent adhesive strength has been required in the use of flexible printed wiring boards (FPC), particularly in the use of bonding FPCs and reinforcing plates. For example, the terminals of flexible printed wiring boards made of polyimide film are lined with reinforcing base materials such as polyimide films, glass epoxy plates, metal plates, etc. to increase their strength. Adhesion between the polyimide film of the wiring board and the reinforcing base material is performed by curing a thermosetting adhesive provided between them (see, for example, Patent Document 2).

Japanese Patent Application Publication No. 2013-203795 JP 2017-17131 Publication

However, in the thermosetting adhesive composition disclosed in Patent Document 1, no consideration is given to tackiness before thermosetting, and when an adhesive sheet is produced using this composition, for example, There was a problem that the tack of the adhesive sheet was insufficient. Furthermore, if the composition is softened to the extent that it has sufficient tack before being thermally cured, there are problems such as insufficient cohesive strength and poor reworkability.

In addition, the technology disclosed in Patent Document 2 described above describes an adhesive sheet obtained by containing an epoxy resin and a curing agent in an acrylic resin with a glass transition temperature of -5 to 15°C, but this does not have sufficient adhesive strength. However, it was necessary to use heat lamination (thermal lamination) to attach it to the adherend, and the transferability at room temperature was not excellent. In the future, from the standpoint of process suitability, there will be a need for room-temperature transferability and reworkability that allow for attachment to adherends at room temperature.

Against this background, the present invention has developed an adhesive that has excellent room-temperature transferability, coating film appearance, and reworkability before curing, and has excellent adhesion to adherends and high adhesive strength after curing. The object of the present invention is to provide an adhesive composition that forms an adhesive.

However, as a result of extensive research in view of the above circumstances, the present inventors have found that a resin containing an acrylic resin (A), an epoxy compound (B), and a curing agent (C) that reacts with the epoxy compound (B) has been found. In the adhesive composition, by using an epoxy compound (b1) with low viscosity and a large epoxy equivalent as the epoxy compound (B), the transferability at room temperature, the appearance of the coating film, and the reworkability are improved before curing. The present invention was completed based on the discovery that it has excellent adhesion to adherends after curing.

That is, the present invention contains an acrylic resin (A), an epoxy compound (B), and a curing agent (C) that reacts with the epoxy compound (B), and the epoxy compound (B) is The first aspect is an adhesive composition containing an epoxy compound (b1) having a viscosity of 2000 mPa·s or less and an epoxy equivalent of 300 g/eq or more.

The second gist of the present invention is a pressure-sensitive adhesive containing the pressure-sensitive adhesive composition which is the first gist.

The third aspect of the present invention is a pressure-sensitive adhesive sheet having a pressure-sensitive adhesive layer containing a pressure-sensitive adhesive, which is the second feature of the invention, The fourth aspect is a laminate in which the contained adhesive layer is laminated on an adherend.

According to the pressure-sensitive adhesive composition of the present invention, it forms a pressure-sensitive adhesive that has excellent room-temperature transferability, coating film appearance, and reworkability before curing, and has excellent adhesion to adherends after curing. be able to. Therefore, the adhesive composition of the present invention can be used for various adhesive applications, such as building materials, automotive parts, electronic parts, semiconductor manufacturing processes, member sealing, aircraft parts, and sporting goods. It can be suitably used for various adhesive applications such as, and is particularly useful for adhering FPCs and reinforcing plates.

In adhesive compositions, it is common practice to incorporate epoxy compounds into acrylic resins, and examples of epoxy compounds include bisphenol A type, bisphenol F type, etc. from the viewpoint of curability and handling properties. Epoxy resins are used, and solid epoxy resins such as polyfunctional type, novolac phenol type, biphenyl type, etc. are used from the viewpoint of creep properties. When these epoxy resins are blended with acrylic resins, there are concerns that tack tends to disappear and transferability at room temperature is poor, and a solution to these concerns is sought.
Therefore, the present invention uses an epoxy compound having a low viscosity and a large epoxy equivalent. Here, if an epoxy compound with low viscosity is used, the cohesiveness of the adhesive layer before curing tends to decrease, the heating during curing tends to volatilize and generate bubbles, and the crosslinking density increases after curing. There is a concern that the adhesive strength tends to decrease due to a high epoxy equivalent, and if an epoxy compound with a large epoxy equivalent is used, there is a concern that the compatibility with the acrylic resin tends to decrease. In the present invention, by intentionally using such an epoxy compound, the coating film has good uniformity, has transferability and reworkability at room temperature before curing, and has excellent adhesive strength after curing, which is surprising. They have also found that the object of the present invention can also be achieved.

The present invention will be explained in detail below.
In the present invention, (meth)acrylic means acrylic or methacrylic, (meth)acryloyl means acryloyl or methacryloyl, and (meth)acrylate means acrylate or methacrylate.

[Adhesive composition]
The adhesive composition of the present invention comprises an acrylic resin (A), an epoxy compound (B), and a curing agent (C) that reacts with the epoxy compound (B) (hereinafter referred to as a curing agent for epoxy compounds (C)). ) or may be simply abbreviated as curing agent (C)).
These compounds will be explained in order below.

<Acrylic resin (A)>
The acrylic resin (A) is a resin obtained by polymerizing a polymerization component containing at least one type of (meth)acrylic monomer, for example, the main component is a (meth)acrylic monomer, and if necessary, other Examples include acrylic resins obtained by polymerizing polymerization components containing various polymerizable monomers.

Note that "containing (meth)acrylic monomer as a main component" means that the (meth)acrylic monomer is usually 40% by weight or more, preferably 50% by weight or more, and more preferably 60% by weight based on the entire polymerization component. It means containing more than

Examples of the (meth)acrylic monomer include (meth)acrylic acid or its derivatives, (meth)acrylamide or its derivatives, and the like.

Examples of the above (meth)acrylic acid derivatives include methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, isopropyl (meth)acrylate, and 2-methyl-2-nitropropyl (meth)acrylate. Acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, s-butyl (meth)acrylate, t-butyl (meth)acrylate, n-pentyl (meth)acrylate, t-pentyl (meth)acrylate, 3- Pentyl (meth)acrylate, 2,2-dimethylbutyl (meth)acrylate, n-hexyl (meth)acrylate, cetyl (meth)acrylate, n-octyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, 4-methyl Examples include alkyl group-containing (meth)acrylates such as -2-propylpentyl (meth)acrylate and n-octadecyl (meth)acrylate.

Other examples of the above (meth)acrylic acid derivatives include cycloalkyl (meth)acrylates such as cyclohexyl (meth)acrylate and cyclopentyl (meth)acrylate; aralkyl (meth)acrylates such as benzyl (meth)acrylate; ; Biphenyloxy structure-containing (meth)acrylates such as biphenyloxyethyl (meth)acrylate; 2-isobornyl (meth)acrylate, 2-norbornylmethyl (meth)acrylate, 5-norbornen-2-yl-methyl (meth) Acrylate, 3-methyl-2-norbornylmethyl (meth)acrylate, dicyclopentenyl (meth)acrylate, dicyclopentenyloxyethyl (meth)acrylate, dicyclopentanyl (meth)acrylate, etc. polycyclic (meth)acrylate; 2-methoxyethyl (meth)acrylate, 2-ethoxyethyl (meth)acrylate, 2-methoxymethoxyethyl (meth)acrylate, 3-methoxybutyl (meth)acrylate, methoxydiethylene glycol (meth)acrylate; ) acrylate, ethoxydiethylene glycol (meth)acrylate, methoxypolyethylene glycol (meth)acrylate, ethyl carbitol (meth)acrylate, phenoxyethyl (meth)acrylate, alkylphenoxypolyethylene glycol (meth)acrylate, etc. containing alkoxy or phenoxy groups ( meth)acrylate; and the like.

Furthermore, 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 6-hydroxy Hydroxyalkyl (meth)acrylates such as hexyl (meth)acrylate, 8-hydroxyoctyl (meth)acrylate, 10-hydroxydecyl (meth)acrylate, 12-hydroxylauryl (meth)acrylate, [4-(hydroxymethyl)cyclohexyl] Hydroxyl group-containing (meth)acrylates such as methyl acrylate, cyclohexanedimethanol mono(meth)acrylate, 2-hydroxy-3-phenoxypropyl (meth)acrylate; glycidyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate glycidyl ether, etc. Epoxy group-containing (meth)acrylate; 2,2,2-trifluoroethyl (meth)acrylate, 2,2,2-trifluoroethylethyl (meth)acrylate, tetrafluoropropyl (meth)acrylate, hexafluoropropyl ( Halogen-containing (meth)acrylates such as meth)acrylate, octafluoropentyl (meth)acrylate, heptadecafluorodecyl (meth)acrylate, 3-chloro-2-hydroxypropyl (meth)acrylate; dimethylaminoethyl (meth)acrylate, etc. alkylaminoalkyl (meth)acrylate; 3-oxetanylmethyl (meth)acrylate, 3-methyl-oxetanylmethyl (meth)acrylate, 3-ethyl-oxetanylmethyl (meth)acrylate, 3-butyl-oxetanylmethyl (meth)acrylate , oxetane group-containing (meth)acrylates such as 3-hexyl-oxetanylmethyl (meth)acrylate; and the like.

Examples of the above (meth)acrylamide derivatives include N-methyl (meth)acrylamide, N,N-dimethyl (meth)acrylamide, N,N-diethyl (meth)acrylamide, N-isopropyl (meth)acrylamide, N- N-alkyl group-containing (meth)acrylamide derivatives such as butyl (meth)acrylamide and N-hexyl (meth)acrylamide; N-methylol (meth)acrylamide, N-hydroxyethyl (meth)acrylamide, N-methylol-N-propane N-hydroxyalkyl group-containing (meth)acrylamide derivatives such as (meth)acrylamide; N-aminoalkyl group-containing (meth)acrylamide derivatives such as aminomethyl (meth)acrylamide and aminoethyl (meth)acrylamide; N-methoxymethyl ( N-alkoxy group-containing (meth)acrylamide derivatives such as meth)acrylamide and N-ethoxymethyl (meth)acrylamide; N-mercaptoalkyl group-containing (meth)acrylamide such as mercaptomethyl (meth)acrylamide and mercaptoethyl (meth)acrylamide Derivatives: Heterocycle-containing (meth)acrylamide derivatives such as N-acryloylmorpholine, N-acryloylpiperidine, N-methacryloylpiperidine, and N-acryloylpyrrolidine.

These (meth)acrylic monomers may be used alone or in combination of two or more. Among these (meth)acrylic monomers, alkyl esters of (meth)acrylic acid are preferably used. The number of carbon atoms in the alkyl group in the (meth)acrylic acid alkyl ester is usually 1 to 20, preferably 1 to 12, more preferably 1 to 8, and still more preferably 1 to 4. The smaller the number of carbon atoms in the alkyl group, the better the compatibility with the epoxy compound (B) described below.

Further, among these (meth)acrylic monomers, it is preferable that the monomer having an acryloyl group is contained in an amount of 25% by weight or more, and preferably 35% by weight or more, based on the total polymerization components of the acrylic resin (A). is more preferable. Note that the upper limit of the content of the monomer having an acryloyl group based on the entire polymerization components of the acrylic resin (A) is 100% by weight. By increasing the content of the monomer having an acryloyl group, the adhesiveness before curing is not impaired, and the transferability after the adhesive layer is formed is excellent, resulting in good handling properties.

As such a monomer having an acryloyl group, acrylic acid or a derivative thereof, acrylamide or a derivative thereof, etc. can be selected from among the various (meth)acrylic monomers mentioned above.

For example, when using an acrylic acid derivative as the monomer having an acryloyl group, the glass transition temperature is high and the molecular weight of the acrylic resin (A) can be easily increased. The above acrylic acid derivatives are preferred. In particular, methyl acrylate is preferred in terms of polymerizability.

Furthermore, in consideration of reactivity with the crosslinking agent (D) for acrylic resins described later, acrylates containing hydroxyl groups are suitable, such as hydroxyalkyl acrylates such as 2-hydroxyethyl acrylate and 4-hydroxybutyl acrylate. is suitable. It is also suitable to use acrylic acid for the same reason as the reason why the above-mentioned acrylate containing a hydroxyl group is suitable.

For example, when using an acrylamide derivative as the monomer having an acryloyl group, dialkyl acrylamide and N-acryloylmorpholine are preferable because they have a high glass transition temperature and are excellent in compatibility with the epoxy compound (B). . In particular, using an acrylamide derivative with a glass transition temperature of 0°C or higher when preparing a homopolymer can maintain a high glass transition temperature of the resulting acrylic resin (A) and improve the adhesion to the adherend. This is preferable in that it can be improved.

The polymerization component constituting the acrylic resin (A) may contain polymerizable monomers (hereinafter referred to as "other polymerizable monomers") other than the (meth)acrylic monomer.
Examples of the other polymerizable monomers include unsaturated carboxylic acids such as crotonic acid, maleic acid, maleic anhydride, fumaric acid, citraconic acid, glutaconic acid, itaconic acid, acrylamide-N-glycolic acid, and cinnamic acid; Carboxylic acid vinyl ester monomers such as vinyl acetate, vinyl propionate, vinyl stearate, and vinyl benzoate; Monomers containing aromatic rings such as styrene and α-methylstyrene; acrylonitrile, methacrylonitrile, vinyl chloride, vinylidene chloride, alkyl Vinyl ether, vinyl toluene, vinyl pyridine, vinyl pyrrolidone, itaconic acid dialkyl ester, fumaric acid dialkyl ester, allyl alcohol, acryl chloride, methyl vinyl ketone, allyltrimethylammonium chloride, dimethylallyl vinyl ketone, and the like. These may be used alone or in combination of two or more.

It is particularly preferable that the polymerization component constituting the acrylic resin (A) contains a functional group-containing monomer. The functional group-containing monomer preferably contains at least one functional group-containing monomer selected from hydroxyl group-containing monomers and carboxyl group-containing monomers. Among these, functional group-containing monomers containing a (meth)acryloyl group are preferred, and functional group-containing monomers containing an acryloyl group are more preferred. Among these, 2-hydroxyethyl acrylate and acrylic acid are particularly preferred.

The content of such a functional group-containing monomer is preferably 0.1 to 30% by weight, more preferably 1 to 25% by weight, based on the total polymerization components constituting the acrylic resin (A). , more preferably 3 to 20% by weight. If the amount of the functional group-containing monomer is too small, the cohesive force when forming the pressure-sensitive adhesive layer tends to decrease, and tackiness and reworkability tend to decrease. On the other hand, if the amount is too high, the storage stability of the adhesive layer tends to decrease and the pot life tends to become short.

As a polymerization method for the acrylic resin (A), conventionally known methods such as solution radical polymerization, suspension polymerization, bulk polymerization, and emulsion polymerization can be used. For example, a method may be mentioned in which appropriately selected polymerization components and a polymerization initiator are mixed or dropped into an organic solvent and polymerized under predetermined polymerization conditions. Among these, solution radical polymerization and bulk polymerization are preferred and stable. Solution radical polymerization is particularly preferred in that an acrylic resin can be obtained.

Examples of organic solvents used in the polymerization reaction include aromatic hydrocarbons such as toluene and xylene; aliphatic hydrocarbons such as hexane; esters such as ethyl acetate and butyl acetate; n-propyl alcohol and isopropyl alcohol. and ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone. These organic solvents may be used alone or in combination of two or more.

Among these organic solvents, esters such as ethyl acetate and butyl acetate are preferred from the viewpoint of ease of polymerization reaction, chain transfer effect, ease of drying when applying the adhesive composition, and safety. Ketones: Ketones such as acetone, methyl ethyl ketone, and methyl isobutyl ketone are preferred, and ethyl acetate is particularly preferred.

In addition, examples of the polymerization initiator used in such solution radical polymerization include 2,2'-azobisisobutyronitrile and 2,2'-azobis-2-methylbutyronitrile, which are common radical polymerization initiators. , 4,4'-azobis(4-cyanovaleric acid), 2,2'-azobis(methylpropionic acid) and other azo initiators; benzoyl peroxide, lauroyl peroxide, di-t-butyl peroxide, cumene Examples include organic peroxides such as hydroperoxides, which can be appropriately selected and used depending on the monomers used. These polymerization initiators may be used alone or in combination of two or more.

In this way, the acrylic resin (A) used in the present invention is obtained.

The weight average molecular weight (Mw) of the acrylic resin (A) is preferably 100,000 to 1,500,000, more preferably 150,000 to 1,000,000, and still more preferably 200,000 to 800,000. If the weight average molecular weight is too small, the toughness and cohesive force of the resulting pressure-sensitive adhesive layer tend to decrease, and the transferability and reworkability tend to decrease. In addition, if the weight average molecular weight is too large, the viscosity becomes too high, which tends to increase scaling during polymerization or to reduce the compatibility with the epoxy compound (B) and the handling properties.

Further, the degree of dispersion [weight average molecular weight (Mw)/number average molecular weight (Mn)] of the acrylic resin (A) is preferably 10 or less, more preferably 7 or less, and still more preferably 5.5 or less. be. If the degree of dispersion is too high, the cohesive force tends to decrease. Note that the lower limit of the degree of dispersion is usually 1.

The weight average molecular weight of the acrylic resin (A) is the weight average molecular weight in terms of the standard polystyrene molecular weight, and is measured using a high performance liquid chromatograph ("Waters 2695 (main unit)" and "Waters 2414 (detector)" manufactured by Nippon Waters Co., Ltd.). Column: Shodex GPC KF-806L (exclusion limit molecular weight: 2×10 ⁷ , separation range: 100 to 2×10 ⁷ , number of theoretical plates: 10,000 plates/piece, packing material: styrene-divinylbenzene copolymer, packing The number average molecular weight can also be measured in the same manner. Further, the degree of dispersion can be determined from the measured values of the weight average molecular weight and number average molecular weight.

The glass transition temperature (Tg) of the acrylic resin (A) is preferably 0°C or higher, more preferably 5 to 250°C, still more preferably 10 to 200°C, particularly preferably 15 to 180°C. If the glass transition temperature is too low, the adhesive strength after curing tends to decrease, and if it is too high, the tack before curing tends to decrease.

Ｔｇ：重合体のガラス転移温度（Ｋ）
Ｔga：モノマーＡのホモポリマーのガラス転移温度（Ｋ） Ｗａ：モノマーＡの重量分率
Ｔgb：モノマーＢのホモポリマーのガラス転移温度（Ｋ） Ｗｂ：モノマーＢの重量分率
Ｔgn：モノマーＮのホモポリマーのガラス転移温度（Ｋ） Ｗｎ：モノマーＮの重量分率
（Ｗａ＋Ｗｂ＋・・・＋Ｗｎ＝１） Note that the glass transition temperature is calculated using the following Fox equation.

Tg: Glass transition temperature (K) of polymer
Tga: Glass transition temperature of homopolymer of monomer A (K) Wa: Weight fraction of monomer A Tgb: Glass transition temperature of homopolymer of monomer B (K) Wb: Weight fraction of monomer B Tgn: Homopolymer of monomer N Glass transition temperature of polymer (K) Wn: Weight fraction of monomer N (Wa+Wb+...+Wn=1)

That is, it is a value calculated by applying the glass transition temperature and weight fraction of each monomer constituting the acrylic resin to the Fox equation.
The glass transition temperature of a homopolymer of the monomers constituting the acrylic resin is usually measured using a differential scanning calorimeter (DSC), and is determined according to JIS K7121-1987 or JIS K 6240. It can be measured by

The refractive index of the acrylic resin (A) is usually 1.440 to 1.600. It is preferable to reduce the difference in refractive index between the members and the members to be laminated, since optical loss at the interface between the members is reduced.

The above refractive index is a value obtained by measuring the acrylic resin (A) made into a thin film using a refractive index measuring device (Abbe Refractometer 1T, manufactured by Atago Co., Ltd.) at 23° C. using the NaD line.

<Epoxy compound (B)>
The epoxy compound (B) used in the present invention contains an epoxy compound (b1) having a viscosity of 2000 mPa·s or less at 25° C. and an epoxy equivalent of 300 g/eq or more.

The epoxy compound (b1) is liquid at 25° C., has a low viscosity, and has a high epoxy equivalent.
The viscosity of the epoxy compound (b1) at 25°C is 2000 mPa·s or less, preferably 1 to 1500 mPa·s, particularly preferably 1 to 1200 mPa·s, and even more preferably 50 to 1000 mPa·s. It is s. If the viscosity is too high, the transferability at room temperature tends to decrease. Note that if the viscosity is too low, it will volatilize during heat curing, tending to generate bubbles and reducing reworkability.
Note that the above viscosity is a value measured using a B-type viscometer in accordance with JIS K 7233.

In addition, the epoxy equivalent is 300 g/eq or more, preferably 310 to 10,000 g/eq, particularly preferably 320 to 5,000 g/eq, even more preferably 350 to 2,500 g/eq, particularly preferably 400 to 2,000 g/eq. It is eq. If the epoxy equivalent is too low, the adhesive strength after curing tends to decrease. Note that if the epoxy equivalent is too high, the viscosity tends to increase, and the room temperature transferability tends to decrease.

In the present invention, the weight average molecular weight of the epoxy compound (b1) is preferably 300 to 5,000, more preferably 350 to 4,000, particularly preferably 400 to 2,000. If the molecular weight is too small, it will tend to volatilize during heat curing, tend to generate bubbles, and reduce reworkability, while if it is too large, the viscosity will tend to increase and room-temperature transferability will tend to decrease.

The epoxy compound (b1) preferably has 1 to 2 epoxy groups in one molecule, particularly preferably 2 epoxy groups. If the number of epoxy groups is too large, the adhesive will become too hard after curing, and adhesive strength will tend to decrease.

Specific examples of the epoxy compound (b1) include "jER871" and "jER YX7400" manufactured by Mitsubishi Chemical Corporation, and "EP-4005", "ED-502" and "ED-502S" manufactured by ADEKA Corporation. , "ED-506", "EPICLON1650-75MPX" and "EPICLON1051-75M" manufactured by DIC Corporation.

In the present invention, it is important to contain the above-mentioned epoxy compound (b1) as the epoxy compound (B). A known epoxy compound (b2) which is commonly used as an adhesive can also be used in combination.

Examples of such epoxy compounds (b2) include monofunctional epoxy compounds having one epoxy group in the molecule and polyfunctional epoxy compounds having two or more epoxy groups. These compounds may be used alone or in combination of two or more.

Examples of the above-mentioned monofunctional epoxy compounds include alkyl glycidyl ether, alkoxy glycidyl ether, phenol glycidyl ether, EO (ethylene oxide) modified phenol glycidyl ether, allyl glycidyl ether, and the like.

Among the above polyfunctional epoxy compounds, examples of bifunctional epoxy compounds having two epoxy groups include neopentyl glycol diglycidyl ether, 1,6-hexanediol diglycidyl ether, ethylene glycol diglycidyl ether, and diethylene glycol diglycidyl ether. Glycidyl ether, polyethylene glycol diglycidyl ether, polypropylene glycol diglycidyl ether, diglycidyl terephthalate, diglycidyl-o-phthalate, diglycidyl resorcinol ether, bisphenol A type diglycidyl compounds and their hydrogenated products, bisphenol F type diglycidyl compounds and their Examples include hydrogenated compounds, biphenyl-type diglycidyl compounds, and derivatives thereof.

Examples of the polyfunctional epoxy compounds having three or more epoxy groups include trifunctional epoxy compounds such as glycerol triglycidyl ether, trimethylolpropane triglycidyl ether, triglycidyl isocyanurate and derivatives thereof, and pentaerythritol triglycidyl ether; Tetrafunctional epoxy compounds such as pentaerythritol tetraglycidyl ether, diglycerol tetraglycidyl ether, and ditrimethylolpropane tetraglycidyl ether; Pentafunctional epoxy compounds such as polyglycerol pentaglycidyl ether, pentaerystol pentaglycidyl ether, and dipentaerystol pentaglycidyl ether Epoxy compounds; sorbitol hexaglycidyl ether: hexafunctional epoxy compounds such as dipentaerythol hexaglycidyl ether; polyglycidyl ethers, phenol novolac type epoxy compounds, cresol novolak type epoxy compounds; and the like.

In the present invention, the content ratio of the epoxy compound (b1) to the entire epoxy compound (B) is preferably 30% by weight or more in terms of room temperature transferability and reworkability before curing, and adhesive strength after curing. , more preferably 50% by weight or more, particularly preferably 60% by weight or more. If the content of the epoxy compound (b1) is too small, the transferability at room temperature before curing tends to deteriorate.

In addition, the viscosity of the epoxy compound (B) including the epoxy compound (b1) as a whole is preferably 1 to 10,000 mPa·s, more preferably 10 to 5,000 mPa·s from the viewpoint of transferability at room temperature before curing. , particularly preferably 50 to 2500 mPa·s. If the viscosity is too low, the cohesive force before curing tends to be insufficient and reworkability tends to decrease, while if it is too high, the room temperature transferability before curing tends to decrease.

The content of the epoxy compound (B) is preferably 1 to 150 parts by weight, more preferably 5 to 120 parts by weight, particularly preferably 7 to 120 parts by weight, based on 100 parts by weight of the acrylic resin (A). The amount is 100 parts by weight, more preferably 10 to 75 parts by weight. If the content of the epoxy compound (B) relative to the acrylic resin (A) is too small, the transferability at room temperature before curing tends to decrease; if it is too large, the cohesive force before curing may decrease or tends to lead to a decrease in adhesive strength.

<Curing agent for epoxy compounds (C)>
The curing agent for epoxy compounds (C) is a compound that is used as a curing agent for the epoxy compound (B) and has a functional group that can react with an epoxy group.
Examples of such curing agents (C) include amines, polyamides, imidazoles, polymercaptan curing agents, acid anhydrides, and the like. These may be used alone or in combination of two or more. Among the above-mentioned curing agents (C), dicyandiamide, which is an amine compound, and organic acid hydrazide are particularly preferred in terms of their excellent storage stability and curability when used as an adhesive. Among the organic acid hydrazides, Particularly preferred are adipic acid dihydrazide and sebacic acid dihydrazide because of their excellent curing speed.

The above curing agent (C) may be either liquid or solid, but from the viewpoint of storage stability when used as an adhesive and the pot life of the adhesive composition, solid It is preferable that the coating film is smooth, and furthermore, it is preferable that the coating film is dispersed and contained in the form of a powder, since the adhesive area with the component increases when it is cured, and the adhesive strength after curing is increased. preferable. When using powder as the hardening agent (C), the particle size of the powder should be set to be 1.2 times or less the film thickness when forming the adhesive layer. is preferable, and more preferably 1 time or less.

When the curing agent (C) is used, its content is preferably 1 to 100 parts by weight, more preferably 3 to 80 parts by weight, based on 100 parts by weight of the epoxy compound (B). More preferably, the amount is particularly preferably 5 to 50 parts by weight. If the content ratio of the curing agent (C) to the epoxy compound (B) is too small than the above range, the curing speed tends to be slow or the curing temperature becomes high; if it is too large, the coating There is a tendency for streaks to occur during processing and for the pot life of the adhesive composition to be shortened.

<Crosslinking agent for acrylic resin (D)>
The adhesive composition of the present invention contains the above-mentioned acrylic resin (A), an epoxy compound (B) containing an epoxy compound (b1), and a curing agent for epoxy compounds (C). However, it is preferable to further contain a crosslinking agent (D) for acrylic resin (hereinafter sometimes abbreviated as crosslinking agent (D)) that crosslinks the acrylic resin (A). By containing the crosslinking agent (D), the adhesive composition can be crosslinked, which is suitable for increasing the cohesive force of the adhesive and improving reworkability. In addition, since the acrylic resin (A) is also crosslinked by the epoxy compound (B), the crosslinking agent (D) in the present invention excludes the epoxy compound (B).

As the crosslinking agent (D) for acrylic resins, known crosslinking agents can be used, such as isocyanate crosslinking agents, aziridine crosslinking agents, melamine crosslinking agents, aldehyde crosslinking agents, metal chelate crosslinking agents, etc. can be mentioned.
These crosslinking agents (D) may be used alone or in combination of two or more.

Examples of the isocyanate crosslinking agent include tolylene diisocyanate compounds such as 2,4-tolylene diisocyanate and 2,6-tolylene diisocyanate; 1,3-xylylene diisocyanate, 1,4-xylylene diisocyanate, and tetra Xylylene diisocyanate compounds such as methylxylylene diisocyanate; aromatic isocyanate compounds such as 1,5-naphthalene diisocyanate and triphenylmethane triisocyanate; hexamethylene diisocyanate, pentamethylene diisocyanate, isophorone diisocyanate, and these isocyanate compounds. Examples include adducts with polyol compounds such as trimethylolpropane, burettes and isocyanurates of these polyisocyanate compounds, and the like.

Examples of the aziridine-based crosslinking agent include tetramethylolmethane-tri-β-aziridinylpropionate, trimethylolpropane-tri-β-aziridinylpropionate, N,N'-diphenylmethane-4,4 '-bis(1-aziridinecarboxamide), N,N'-hexamethylene-1,6-bis(1-aziridinecarboxamide), and the like.

Examples of the melamine-based crosslinking agent include hexamethoxymethylmelamine, hexaethoxymethylmelamine, hexapropoxymethylmelamine, hexabutoxymethylmelamine, hexapentyloxymethylmelamine, hexahexyloxymethylmelamine, and melamine resins.

Examples of the aldehyde crosslinking agent include glyoxal, malondialdehyde, succindialdehyde, maleic dialdehyde, glutardialdehyde, formaldehyde, acetaldehyde, benzaldehyde, and the like.

Examples of the metal chelate crosslinking agents include acetylacetone and acetoacetyl ester coordination compounds of polyvalent metals such as aluminum, iron, copper, zinc, tin, titanium, nickel, antimony, magnesium, panadium, chromium, and zirconium. Can be mentioned.

In the present invention, the content of the crosslinking agent (D) is preferably 0 to 15 parts by weight, more preferably 0.1 to 10 parts by weight, particularly preferably 0.1 to 10 parts by weight, based on 100 parts by weight of the acrylic resin (A). is 0.5 to 5 parts by weight, more preferably 1 to 3 parts by weight. If the content of the crosslinking agent (D) is too large, the tack when forming the adhesive layer tends to decrease.

<Optional ingredients>
In the present invention, in addition to the above-mentioned components, optional components include, for example, conductive agents such as carbon and metal; inorganic fillers such as metal particles and glass particles; urethane resin, rosin, rosin ester, hydrogenated rosin ester, and phenol. Tackifiers such as resins, aliphatic petroleum resins, alicyclic petroleum resins, styrene resins; fillers; antioxidants; ultraviolet absorbers; silane coupling agents; ionic compounds, peroxides, urethanization Various additives such as a crosslinking promoter such as a catalyst; a crosslinking retarder such as acetylacetone; and the like can also be contained. These may be used alone or in combination of two or more.

In addition to the above-mentioned optional components, the adhesive composition of the present invention may also contain impurities contained in the raw materials for manufacturing the constituent components of the adhesive composition to the extent that they do not impair the effects of the present invention. You may do so.

The adhesive composition of the present invention comprises an acrylic resin (A), an epoxy compound (B), a curing agent for epoxy compounds (C), and, if necessary, a crosslinking agent for acrylic resins (D). and other optional components.
The method of mixing these components is not particularly limited, and various methods may be used, such as a method of mixing each component at once, a method of mixing any component, and then mixing the remaining components at once or sequentially. can be adopted.

[Adhesives, adhesive sheets, and laminates]
The adhesive composition of the present invention can be made into an adhesive by crosslinking the acrylic resin (A). Furthermore, by laminating an adhesive layer containing this adhesive on a base material such as a plastic film, it is possible to obtain an adhesive sheet having a laminated structure of base material/adhesive layer. can. Furthermore, by laminating this adhesive layer on an adherend, a laminate having a laminated structure of adherend/adhesive layer can be obtained. Note that hereinafter, the base material and the adherend will also be collectively referred to as "members."

The above-mentioned adhesive sheets include adhesive sheets with an adhesive layer laminated on a base material, as well as double-sided adhesive sheets with no base material, in which separators (release sheets) are laminated on both sides of the adhesive layer. Adhesive sheets are available, and double-sided adhesive sheets are preferred in terms of ease of handling.

The method for manufacturing the above-mentioned adhesive sheet includes, for example, applying an adhesive composition onto a base material, drying it, laminating a separator thereon, aging it at room temperature (without heating), etc. Examples include a method of performing aging treatment by at least one of aging in a heated state. In addition, after applying the adhesive composition to a separator and drying it, the separator is laminated with another separator with a different peel strength, and an aging treatment is performed to create a double-sided adhesive adhesive without a base material. sheets can be manufactured.

The above aging treatment is a treatment performed to chemically crosslink the acrylic resin (A) and the crosslinking agent (D) to develop appropriate tackiness in the adhesive, and the aging conditions include, for example. , the temperature is usually room temperature (20±10°C) to 40°C, and the time is usually 1 to 30 days, specifically, for example, 23°C for 1 to 20 days, 40°C for 1 to 7 days, etc. There are conditions.
Note that when the crosslinking agent (D) is not used, aging treatment is not necessarily necessary.

When applying the pressure-sensitive adhesive composition, it is preferable to dilute the pressure-sensitive adhesive composition with a solvent, and the solid content concentration is preferably 5 to 65% by weight, more preferably 20% by weight. ~55% by weight.
Moreover, the above-mentioned solvent is not particularly limited as long as it dissolves the adhesive composition. For example, ester solvents such as methyl acetate, ethyl acetate, methyl acetoacetate, and ethyl acetoacetate; ketone solvents such as acetone, methyl ethyl ketone, and methyl isobutyl ketone; aromatic solvents such as toluene and xylene; methanol, ethanol, and propyl alcohol. Alcohol-based solvents such as; and the like can be used. Among these, ethyl acetate is preferably used in terms of solubility, drying properties, price, etc.

The viscosity of the diluted pressure-sensitive adhesive composition is preferably 500 to 15,000 mPa·s/25°C, more preferably 1,000 to 10,000 mPa·s/25°C. If the viscosity is too low, when a component with a heavy specific gravity is used, the component tends to settle, and the concentration of the component in the pressure-sensitive adhesive composition tends to become non-uniform.

Examples of methods for applying the pressure-sensitive adhesive composition include roll coating, die coating, gravure coating, comma coating, and screen printing.

The thickness of the adhesive layer in the adhesive sheet is preferably 5 to 250 μm, more preferably 25 to 200 μm, and still more preferably 50 to 175 μm. If the above-mentioned adhesive layer is too thin, the thickness accuracy tends to decrease or the adhesive force becomes low.If the above-mentioned adhesive layer is too thick, when the adhesive sheet is rolled The adhesive layer tends to protrude from the edges.

The gel fraction of the adhesive layer is preferably 99% by weight or less, more preferably 95% by weight or less, and even more preferably 80% by weight from the viewpoint of adhesion with the member, reworkability, and tackiness before curing. It is as follows. If the gel fraction of the adhesive layer is too high, sufficient adhesion between the adhesive layer and the component interface cannot be obtained when the adhesive sheet is bonded to the component, resulting in poor adhesive strength after curing. There is a tendency to decrease. Note that the lower limit of the gel fraction is usually 0% by weight.

The above gel fraction serves as a guideline for the degree of crosslinking (degree of curing), and is calculated, for example, by the following method. First, the adhesive was collected from an adhesive sheet with an adhesive layer laminated on the surface of the base material by picking, wrapped in a 200 mesh SUS wire mesh, and heated to 23°C. Soak in adjusted ethyl acetate for 24 hours. The weight of the adhesive layer before and after immersion in ethyl acetate is measured, and the difference between the two weights is taken as the weight of the undissolved adhesive component remaining in the wire gauze. The weight percentage of the undissolved adhesive component remaining in the wire mesh with respect to the weight of the adhesive layer before immersion in ethyl acetate is defined as the gel fraction.

In the present invention, since the above-mentioned adhesive has a function of curing by heating at a predetermined temperature, the adhesive force of the adhesive layer in the adhesive sheet increases, and the adhesive sheet adheres to the adherend. stick.
The heating temperature when curing the adhesive is preferably 100 to 250°C, more preferably 120 to 200°C, still more preferably 130 to 185°C. If the temperature is too low, the curing time tends to be long and workability decreases; if the temperature is too high, the epoxy compound (B) tends to volatilize or catch fire. Further, the heating time is preferably 5 to 180 minutes, more preferably 30 to 120 minutes, and still more preferably 45 to 90 minutes. If this time is too short, curing will be insufficient and adhesive strength will tend to decrease, while if it is too long, workability will tend to decrease.

Adhesive sheets with an adhesive layer laminated on the surface of a separator can be easily attached by simply peeling off the separator and attaching the adhesive layer to the desired adherend surface. Since the adhesive layer can be transferred, the work efficiency is very high.

Furthermore, a laminate formed by laminating other members through the above-mentioned adhesive layer, that is, a laminate having a laminated structure of adherend/adhesive layer/other member, Since the layer has high adhesiveness before curing and exhibits high adhesive strength after curing, other members are unlikely to easily shift or peel off from the adherend. Therefore, by using the adhesive of the present invention, a laminate with high adhesive reliability and excellent appearance can be obtained.

The pressure-sensitive adhesive composition of the present invention has excellent room-temperature transferability, coating film appearance, and reworkability before curing, and after curing forms a pressure-sensitive adhesive with excellent adhesion to adherends. can.
Therefore, the adhesive composition of the present invention can be used for various adhesive applications, such as building materials, automotive parts, electronic parts, semiconductor manufacturing processes, member sealing, aircraft parts, and sporting goods. It can be suitably used for various adhesive applications such as.

The present invention is particularly useful for the use of flexible printed circuit boards (FPC), for example, for adhering FPCs and reinforcing plates. There is no need to use heat lamination (thermal lamination) for attachment, it can be attached to an adherend at room temperature, and it has good reworkability, so it is highly anticipated.

EXAMPLES Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited to the following examples unless it exceeds the gist thereof. In addition, in the examples, "parts" and "%" mean weight basis.
In addition, the weight average molecular weight, degree of dispersion, glass transition temperature, and other physical properties of the acrylic resin in the following examples were measured according to the methods described above.
First, prior to the example, the following components were prepared.

<Acrylic resin (A)>
[Preparation of acrylic resin (A-1)]
In a 4-neck round bottom flask equipped with a reflux condenser, a stirrer, a nitrogen gas inlet, and a thermometer, 80 parts of ethyl acetate, 6 parts of methyl ethyl ketone, and 0% of azobisisobutyronitrile (AIBN) as a polymerization initiator were added. After charging .036 parts and heating until the internal temperature reached the boiling point, add 40 parts of methyl acrylate (MA), 10 parts of methyl methacrylate (MMA), 45 parts of n-butyl methacrylate, and 5 parts of 2-hydroxyethyl acrylate (2HEA). A mixed solution of 0.1 part of acrylic acid (AAc), 4 parts of ethyl acetate, and 0.036 parts of a polymerization initiator (AIBN) was added dropwise over 2 hours while maintaining the boiling state. Thereafter, while continuing the reaction, 0.05 part of a polymerization initiator (AIBN) was added twice, and after reacting for 7 hours, it was diluted and the acrylic resin (A-1) solution (solid content concentration 45. 1%, viscosity 12,400 mPa・s/25°C, acrylic resin (A-1): weight average molecular weight (Mw) 288,000, dispersity (Mw/Mn) 2.2, glass transition temperature (Tg) 19.7°C) was obtained.

<Epoxy compound (B)>
The following epoxy compounds (B) were prepared.
(B-1): jER YX7400 (manufactured by Mitsubishi Chemical Corporation) Viscosity at 25°C 200 mPa・s, Epoxy equivalent 440 g/eq
(B-2): jER YX7105 (manufactured by Mitsubishi Chemical Corporation) Viscosity at 25°C 53,000 mPa・s, Epoxy equivalent 480 g/eq
(B-3): Denacol EX-321 (manufactured by Nagase ChemteX), viscosity at 25°C 140 mPa・s, epoxy equivalent 140 g/eq
(B-4): jER 828 (manufactured by Mitsubishi Chemical Corporation) Viscosity at 25°C 13,500 mPa・s, Epoxy equivalent 189 g/eq
(B-5): jER 1032H60 (manufactured by Mitsubishi Chemical Corporation) Solid at 25°C, epoxy equivalent 160g/eq

<Curing agent for epoxy compounds (C)>
The following were prepared as the curing agent (C) for epoxy compounds.
(C-1): Adipic acid dihydrazide (ADH-S: manufactured by Otsuka Chemical Co., Ltd.)

<Crosslinking agent for acrylic resin (D)>
The following crosslinking agents (D) for acrylic resins were prepared.
(D-1): Coronate L55E (manufactured by Tosoh Corporation: adduct of trimethylolpropane and tolylene diisocyanate)

<Examples 1 to 4, Comparative Examples 1 to 5>
A pressure-sensitive adhesive composition was obtained by blending the above components according to Table 1 below and adjusting the solid content concentration to a range of 30 to 60% using ethyl acetate.

A pressure-sensitive adhesive sheet was prepared from the obtained pressure-sensitive adhesive composition according to the procedure shown below. Thereafter, using this adhesive sheet, the appearance of the coating film of the adhesive sheet before curing, room temperature transferability, reworkability, and adhesive strength of the adhesive sheet before curing were evaluated as described below.
The evaluation method and evaluation criteria for each item are as follows. These results are also shown in Table 1 below.

<Preparation of adhesive sheet>
The adhesive composition was coated on a 38 μm thick heavy release silicone separator (manufactured by Mitsui Chemicals Tohcello Co., Ltd., "SPPET03 38BU") using a comma coater so that the thickness after drying was 50 μm, and then heated at 100°C. It was dried for 3 minutes to form an adhesive layer. A 38 μm thick easy-release silicone separator (manufactured by Mitsui Chemicals Tohcello, Inc., "SPPET01 38BU") was attached to the surface of the adhesive layer, and then aged at 40°C for 3 days to produce an adhesive sheet ( laminate of light release silicone separator/adhesive layer/heavy release silicone separator).

[Appearance of paint film]
The appearance of the coating film of the pressure-sensitive adhesive sheet prepared above was visually confirmed and evaluated based on the following criteria.
○: No roughness, unevenness, or bubbles were observed on the coating surface.
Δ: Slight bubbles were observed on the surface of the coating film.
×: Roughness or unevenness was observed on the surface of the coating film, or a large number of bubbles were observed.

[Room temperature transferability]
The light-release silicone separator of the adhesive sheet prepared above was peeled off, and the adhesive layer side was bonded to a polyimide film (Kapton 200H, manufactured by DuPont Toray) at room temperature, and the adhesive sheet with film base material was attached. I got it. When the heavy-release silicone separator was peeled off from the obtained adhesive sheet with film base material, it was visually confirmed whether the adhesive layer was transferred to the polyimide film, and evaluation was made according to the following criteria.
○・・・Transferred ×・・・Not transferred

[Reworkability]
The light-release silicone separator of the adhesive sheet prepared above was peeled off, and the adhesive layer side was bonded to a polyimide film (Kapton 200H, manufactured by DuPont Toray) at room temperature, and the adhesive sheet with film base material was attached. I got it. The heavy-release silicone separator was peeled off from the obtained adhesive sheet with film base material, and the adhesive layer side was attached to a SUS-BA plate by moving a 1 kg roller back and forth twice at room temperature. After 30 minutes, the film base was removed. The adhesive sheet with material was peeled off by hand. The surface of the SUS-BA plate after peeling was visually confirmed and evaluated according to the following criteria.
○...No contamination ×...Glue residue

[Adhesive strength after curing]
The light-release silicone separator of the adhesive sheet prepared above was peeled off, and the adhesive layer side was bonded to a polyimide film (Kapton 200H, manufactured by DuPont Toray) at room temperature, and the adhesive sheet with film base material was attached. I got it. After cutting out the obtained adhesive sheet with film base material into a width of 25 mm, the heavy release silicone separator was peeled off, and the adhesive layer side was pasted on a SUS-BA plate by moving a 1 kg roller back and forth twice at room temperature. After applying, it was heated and cured at 160°C for 1 hour. After controlling the temperature in an environment of 23°C x 50% RH, the adhesive strength (unit: N/cm) was measured at 180° peeling at a speed of 300 mm/min using AUTO Graph AG-X Plus (manufactured by Shimadzu Corporation). was measured and evaluated based on the following criteria.
◎...Higher than 15N/cm 〇...10-15N/cm
×...Less than 10/Ncm

From the above results, in Examples 1 to 4 using the adhesive composition containing the epoxy compound (B) including the epoxy compound (b1), the coating film appearance, room temperature transferability, reworkability, and adhesiveness It is excellent in both powers.
On the other hand, in Comparative Examples 1 to 5 using pressure-sensitive adhesive compositions that do not contain the epoxy compound (b1), the desired effects were not obtained in any of the above evaluations, and the objective of the present invention was not achieved. It turned out that it could not be achieved.

The pressure-sensitive adhesive composition of the present invention has excellent room-temperature transferability, coating film appearance, and reworkability before curing, and after curing forms a pressure-sensitive adhesive with excellent adhesion to adherends. can. Therefore, the adhesive composition of the present invention can be used for various adhesive applications, such as building materials, automotive parts, electronic parts, semiconductor manufacturing processes, member sealing, aircraft parts, and sporting goods. It can be suitably used for various adhesive applications such as, and is particularly useful for adhering FPCs and reinforcing plates.

Claims (10)

It contains an acrylic resin (A), an epoxy compound (B ) , a curing agent (C) that reacts with the epoxy compound (B), and a crosslinking agent (D), and the epoxy compound (B) is An adhesive composition comprising an epoxy compound (b1) having a viscosity of 2000 mPa·s or less, an epoxy equivalent of 300 g/eq or more , and a weight average molecular weight of 300 to 5000 . The pressure-sensitive adhesive composition according to claim 1 , wherein the epoxy compound (b1) has 1 to 2 epoxy groups in one molecule. 3. The pressure-sensitive adhesive composition according to claim 1, wherein the content of the epoxy compound (b1) relative to the entire epoxy compound (B) is 30% by weight or more. The adhesive according to any one of claims 1 to 3 , wherein the content of the epoxy compound (B) is 5 to 150 parts by weight based on 100 parts by weight of the acrylic resin (A). Adhesive composition. The pressure-sensitive adhesive composition according to any one of claims 1 to 4 , wherein the acrylic resin (A) has a weight average molecular weight of 200,000 or more. The pressure-sensitive adhesive composition according to any one of claims 1 to 5 , wherein the acrylic resin (A) has a glass transition temperature of 0°C or higher. An adhesive comprising the adhesive composition according to any one of claims 1 to 6 . The pressure-sensitive adhesive according to claim 7 , which has a function of curing by heating at 100 to 250°C. An adhesive sheet comprising an adhesive layer containing the adhesive according to claim 7 or 8 . A laminate, characterized in that a pressure-sensitive adhesive layer containing the pressure-sensitive adhesive according to claim 7 or 8 is laminated on an adherend.