JP2020070345A - Pressure-sensitive adhesive composition, and pressure-sensitive adhesive agent and pressure-sensitive adhesive sheet using the same, and laminate - Google Patents

Abstract

To provide a pressure-sensitive adhesive composition forming a pressure-sensitive adhesive which is excellent in a holding force and transferability of a pressure-sensitive agent before curing and is also excellent in shear strength after curing.SOLUTION: A pressure-sensitive adhesive composition contains an acrylic resin (A), an epoxy-based compound (B) and a crosslinking agent (C) (excluding epoxy-based compound (B)) of the acrylic resin (A), in which the acrylic resin (A) is a polymer of a polymerization component containing 33 wt.% or more of a monomer (a1) having an acryloyl group with respect to the total of the polymerization component, a glass transition temperature is 0°C or higher, and a content of the epoxy-based compound (B) is 40-250 pts.mass with respect to 100 pts.wt. of the acrylic resin (A).SELECTED DRAWING: None

Description

  TECHNICAL FIELD The present invention relates to a tacky-adhesive composition, and more specifically to a tacky-adhesive composition that has tackiness under normal conditions and is cured by heating and firmly adhered after being adhered to an adherend. The present invention also relates to a tacky adhesive obtained by crosslinking the above tacky adhesive composition, which has a good tack feeling and is excellent in transferability to a member such as a metal or a plastic film. Further, the present invention provides an adhesive / adhesive sheet having an adhesive / adhesive layer made of the adhesive / adhesive, or an adhesive / adhesive layer made of the adhesive / adhesive and another member, which are laminated together. TECHNICAL FIELD The present invention relates to a laminate having excellent holding strength for a mating surface and shear strength.

  Conventionally, liquid adhesives using epoxy compounds have been used for bonding metals and plastics. In addition, recently, as a tacky adhesive that has both properties of a pressure-sensitive adhesive and an adhesive, which has adhesiveness under normal conditions, and is hardened by heating after being adhered to an adherend to firmly bond, A thermosetting pressure-sensitive adhesive composition using a base resin and an epoxy resin has also been proposed (see, for example, Patent Document 1).

  However, the glass transition temperature of the acrylic resin which has been specifically verified in Patent Document 1 is low, and these are inferior in shear strength after thermosetting.

  On the other hand, a thermosetting resin composition using an acrylic resin having a high glass transition temperature and an epoxy compound has been proposed (for example, see Patent Document 2).

JP-A-4-189884 JP, 2017-331301, A

  However, the tacky-adhesive agent comprising the thermosetting resin composition disclosed in Patent Document 2 has excellent shear strength after curing, but since the content of the epoxy compound relative to the acrylic resin is low, the thermosetting resin is not yet cured. The tackiness of the adhesive / adhesive layer is low, and it cannot be attached to a member (adherend) unless laminated at high temperature, resulting in poor workability.

  In addition, in these adhesives, when the amount of the epoxy compound is simply increased, tackiness is obtained, but since an acrylic resin having a high content of methacrylate monomer is used as a copolymerization component, before curing. The tacky adhesive of (1) has a problem of poor transferability to a member.

  Here, the "transferability" means that after the adhesive layer is formed on the release film, the adhesive layer is adhered to and adhered to the surface of the member to be adhered, and then the adhesive film is adhered. It means the ability to transfer the agent layer to the member cleanly without being able to transfer it to the member or tearing it apart. Moreover, the above-mentioned "crying" means a phenomenon in which peeling cannot occur at a desired interface and peeling occurs at an interface other than the desired interface.

  Under the circumstances, the present invention provides a tacky adhesive composition that forms a tacky adhesive that is excellent in holding force and transferability of the tacky adhesive before curing and also has excellent shear strength after curing. It is an attempt to provide something.

  However, as a result of intensive studies conducted by the present inventors in view of such circumstances, a monomer having an acryloyl group was identified in a pressure-sensitive adhesive composition containing an acrylic resin, an epoxy compound, and a crosslinking agent for the acrylic resin. By using an acrylic resin having a high glass transition temperature of 0 ° C. or more and a large amount of an epoxy compound, it is excellent in holding power before transfer and transferability and has high shear strength after curing. The present invention has been completed by finding that an excellent adhesive can be obtained.

  That is, the present invention provides a pressure-sensitive adhesive containing an acrylic resin (A), an epoxy compound (B) and a cross-linking agent (C) of the acrylic resin (A) (excluding the epoxy compound (B)). A binder composition, wherein the acrylic resin (A) is a polymer of a polymerization component containing the acryloyl group-containing monomer (a1) in an amount of 33% by weight or more based on the entire polymerization component, and a glass transition. The temperature is 0 ° C. or higher, and the content of the epoxy compound (B) is 40 to 250 parts by weight relative to 100 parts by weight of the acrylic resin (A). Use as a summary.

  Moreover, this invention makes the adhesive composition which the said adhesive composition which is the said 1st summary crosslinks be the 2nd summary.

  Furthermore, the present invention provides a pressure-sensitive adhesive sheet having a pressure-sensitive adhesive layer made of a pressure-sensitive adhesive, which is the second aspect, as a third aspect, and also from the pressure-sensitive adhesive which is the second aspect. A fourth aspect is a laminated body in which the adhesive / adhesive layer and the other member are laminated.

  In the present invention, “curing” means curing of the epoxy compound by heating, and the reaction between the acrylic resin and the crosslinking agent is simply referred to as “crosslinking”.

  The pressure-sensitive adhesive obtained using the pressure-sensitive adhesive composition of the present invention has excellent transferability and holding power in the state before curing and exhibits high shear strength in the state after curing, which is an excellent feature. Have Therefore, the adhesive composition of the present invention can be used in various applications such as building materials, vehicle parts, electronic parts, semiconductor manufacturing processes, member encapsulation, aviation parts, and sports goods. It can be suitably used for adhesive applications.

  More specifically, conventionally, an acrylic resin having a high glass transition temperature is used to increase the shear strength after curing, and a predetermined epoxy compound is used to impart tack to the adhesive layer before curing, Those using a cross-linking agent of an acrylic resin to improve the holding power have a problem that the transferability is inferior. On the other hand, in the present invention, not a monomer having a methacryloyl group but a polymer having a polymerization component containing a monomer (a1) having an acryloyl group in a certain proportion or more, and having a high glass transition temperature of 0 ° C. or more, By using a different acrylic resin (A), the above-mentioned problems are solved and the adhesive layer can be smoothly transferred to the member. Further, by containing a relatively large amount of the epoxy compound (B), which was conventionally contained in a small amount, the holding power and the shear strength after curing were significantly improved.

  In addition, in the adhesive composition of the present invention, in particular, the acrylic resin (A) further contains a functional group-containing monomer containing at least one monomer selected from a hydroxyl group-containing monomer and a carboxy group-containing monomer. A polymer of a polymerizing component contained as a polymerizing component is particularly preferable because it has excellent retention of the pressure-sensitive adhesive layer before curing and shear strength of the pressure-sensitive adhesive layer after curing.

  Further, among the adhesive / adhesive compositions of the present invention, particularly those in which the epoxy compound (B) is a liquid epoxy compound at 25 ° C., particularly, the adhesive strength of the adhesive / adhesive layer before curing. It is preferable because it has an excellent balance of holding power, tack, and the like.

  Further, among the tacky-adhesive compositions of the present invention, those containing a curing agent (D) that reacts with the epoxy compound (B) are particularly efficiently cured when used as a tacky-adhesive. It is possible and preferable.

  Among the adhesives of the present invention, those that are cured by heating at 100 to 250 ° C. are particularly preferable because the curing time and the quality retention of the adhesive layer are easy to manage. ..

  Among the adhesives of the present invention, those having a ratio of the shear strength (MPa) after curing to the shear strength (MPa) before curing of 10 or more are particularly adhesive physical properties before curing. Also, it is preferable since the balance of the adhesive strength after curing becomes good.

The present invention will be described in detail below.
In the present invention, the “monomer having an acryloyl group” means a monomer having a group represented by the general formula “CH ₂ ═CH ₂ —CO—”, and the “(meth) acryl” means acryl or methacryl. , "(Meth) acryloyl" means acryloyl or methacryloyl, and "(meth) acrylate" means acrylate or methacrylate.
Further, the "acrylic resin" is a resin obtained by polymerizing a polymerization component containing at least one kind of (meth) acrylate monomer.

  In the present invention, the “glass transition temperature” is a value measured by using a differential scanning calorimeter (TA Instruments, DSC Q2000). The measurement temperature range is -85 ° C to 200 ° C, and the temperature rising rate is 5 ° C / minute.

  The pressure-sensitive adhesive composition of the present invention contains an acrylic resin (A), an epoxy compound (B), and a crosslinking agent (C) for the acrylic resin (A). Hereinafter, the above (A), (B), and (C) will be described in order.

<Acrylic resin (A)>
Examples of the acrylic resin (A) include acrylic resins obtained by polymerizing a polymerization component containing a (meth) acrylic monomer as a main component and optionally other various polymerizable monomers.
The term "mainly composed of" means that the content of the polymerization component is usually 40% by weight or more, preferably 50% by weight or more, and more preferably 60% by weight or more.

  Examples of the (meth) acrylic monomer include (meth) acrylic acid or a derivative thereof, and (meth) acrylamide or a derivative thereof.

  Examples of the (meth) acrylic acid derivative include methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, isopropyl (meth) acrylate, and 2-methyl-2-nitropropyl (meth). 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 -2-propylpentyl Meth) acrylate, containing alkyl groups such as n- octadecyl (meth) acrylate (meth) acrylate.

  Other examples of the (meth) acrylic acid derivative include cycloalkyl (meth) acrylates such as cyclohexyl (meth) acrylate and cyclopentyl (meth) acrylate; aralkyl (meth) acrylates such as benzyl (meth) acrylate. A biphenyloxy structure-containing (meth) acrylate 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, Polycyclic (me ) Acrylate; 2-methoxyethyl (meth) acrylate, 2-ethoxyethyl (meth) acrylate, 2-methoxymethoxyethyl (meth) acrylate, 3-methoxybutyl (meth) acrylate, methoxydiethylene glycol (meth) acrylate, ethoxydiethylene glycol ( (Meth) acrylate, methoxy polyethylene glycol (meth) acrylate, ethyl carbitol (meth) acrylate, phenoxyethyl (meth) acrylate, alkylphenoxy polyethylene glycol (meth) acrylate, or other alkoxy group or phenoxy group-containing (meth) acrylate; Can be mentioned.

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

  Examples of the (meth) acrylamide derivative include N-methyl (meth) acrylamide, N, N-dimethyl (meth) acrylamide, N, N-diethyl (meth) acrylamide, N-isopropyl (meth) acrylamide, N-alkyl group-containing (meth) acrylamide derivatives such as N-butyl (meth) acrylamide, N-hexyl (meth) acrylamide; N-methylol (meth) acrylamide, N-hydroxyethyl (meth) acrylamide, N-methylol-N -N-hydroxyalkyl group-containing (meth) acrylamide derivatives such as propane (meth) acrylamide; N-aminoalkyl group-containing (meth) acrylamide derivatives such as aminomethyl (meth) acrylamide and aminoethyl (meth) acrylamide; N-methoxy N-alkoxy group-containing (meth) acrylamide derivatives such as chill (meth) acrylamide and N-ethoxymethyl (meth) acrylamide; N-mercaptoalkyl group-containing (meta) such as mercaptomethyl (meth) acrylamide and mercaptoethyl (meth) acrylamide ) Acrylamide derivatives; heterocyclic ring-containing (meth) acrylamide derivatives such as N-acryloylmorpholine, N-acryloylpiperidine, N-methacryloylpiperidine, N-acryloylpyrrolidine and the like.

  These (meth) acrylic monomers may be used alone or in combination of two or more. Among these, a monomer that is an alkyl ester of (meth) acrylic acid is preferably used, and an alkyl (meth) acrylate having 1 to 20 carbon atoms is particularly preferable. Further, those having 1 to 12 carbon atoms are preferable, those having 1 to 8 are more preferable, and those having 1 to 4 are particularly preferable. This is because the smaller the number of carbon atoms, the better the compatibility with the epoxy compound (B) described below.

  Then, in the present invention, it is necessary that, of these (meth) acrylic monomers, the monomer (a1) having an acryloyl group is contained in an amount of 33% by weight or more based on the entire polymerization components of the acrylic resin (A). , Preferably 35 to 100% by weight, more preferably 50 to 100% by weight. By increasing the content ratio of the monomer (a1) having an acryloyl group, the transferability after the formation of the adhesive layer becomes excellent and the handleability becomes good without impairing the adhesive property before curing. ..

  In the present invention, the monomer (a1) having such an acryloyl group contains an acryloyl group such as acrylic acid or a derivative thereof, acrylamide or a derivative thereof among the above-mentioned various (meth) acrylic monomers. A monomer can be selected and used.

  When an acrylic acid derivative, for example, is used as the monomer (a1) having an acryloyl group, the homopolymer is high in glass transition temperature, tends to have high shear strength after curing, and easily increases the molecular weight of the acrylic resin. In this case, a monomer having a glass transition temperature of 0 ° C. or higher is preferable, and it is preferable that methyl acrylate is contained from the viewpoint of polymerizability.

  When the glass transition temperature is high, the shear strength after curing tends to be high, and the reactivity with the crosslinking agent (C) described later is taken into consideration, 2-hydroxyethyl acrylate, 4-hydroxybutyl acrylate, etc. , Hydroxyalkyl acrylate and the like, which contain a hydroxyl group, are preferred. It is also preferable to use acrylic acid for the same reason as that containing the above hydroxyl group.

  When an acrylamide derivative is used as the acryloyl group-containing monomer (a1), for example, it has a high glass transition point and is excellent in compatibility with the epoxy compound (B), so that it is dialkylacrylamide or N-acryloylmorpholine. Is preferably included.

  Further, among the monomers (a1) having an acryloyl group, it is preferable to use a large amount of an acryloyl group-containing monomer having a glass transition temperature of 0 ° C. or higher when formed into a homopolymer, because the glass transition temperature of the resulting acrylic resin (A) is Can be maintained high, which is preferable.

  In the present invention, as the polymerizable monomer other than the (meth) acrylic monomer that can be used for the acrylic resin (A) (hereinafter, referred to as “other polymerizable monomer”), for example, crotonic acid, maleic acid, Unsaturated carboxylic acids such as maleic anhydride, fumaric acid, citraconic acid, glutaconic acid, itaconic acid, acrylamido N-glycolic acid, cinnamic acid; carboxylic acids such as vinyl acetate, vinyl propionate, vinyl stearate, vinyl benzoate, etc. Vinyl ester monomer; Aromatic ring-containing monomer such as styrene and α-methylstyrene; Acrylonitrile, methacrylonitrile, vinyl chloride, vinylidene chloride, alkyl vinyl ether, vinyltoluene, vinylpyridine, vinylpyrrolidone, itaconic acid dialkyl ester, fumaric acid Dialkyl Ester, allyl alcohol, acrylic chloride, methyl vinyl ketone, allyl trimethyl ammonium chloride, dimethyl allyl vinyl ketone. These may be used alone or in combination of two or more.

  In the present invention, it is preferable to contain a functional group-containing monomer regardless of the presence or absence of a (meth) acryloyl group, and the functional group-containing monomer is at least one monomer selected from a hydroxyl group-containing monomer and a carboxy group-containing monomer. It is preferable that the monomer contains a functional group-containing monomer. Among them, a functional group-containing monomer having a (meth) acryloyl group is preferable, and a functional group-containing monomer having an acryloyl group is more preferable.

  And, the content of the functional group-containing monomer is preferably 0.1 to 30% by weight, more preferably 1 to 25% by weight, based on the entire polymerization components in the acrylic resin (A). Particularly preferably, it is 3 to 20% by weight. If the amount of the functional group-containing monomer is too small, the cohesive force tends to decrease when the pressure-sensitive adhesive is used. On the contrary, if the amount is too high, the storage stability of the pressure-sensitive adhesive decreases and the pot life becomes short. There is a tendency to become.

  As a method for polymerizing the acrylic resin (A), conventionally known methods such as solution radical polymerization, suspension polymerization, bulk polymerization, emulsion polymerization and the like can be used. For example, there is a method of mixing or dropping a properly selected polymerization component and a polymerization initiator in an organic solvent, and performing polymerization under predetermined polymerization conditions. Among them, solution radical polymerization and bulk polymerization are preferable and stable. Solution radical polymerization is particularly preferable in that an acrylic resin can be obtained.

  Examples of the organic solvent 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, isopropyl alcohol. And aliphatic ketones, acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, and other ketones. These organic solvents can be used alone or in combination of two or more kinds.

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

  Examples of the polymerization initiator used for such radical polymerization include 2,2′-azobisisobutyronitrile, 2,2′-azobis-2-methylbutyronitrile, which are ordinary radical polymerization initiators. Azo initiators such as 4,4′-azobis (4-cyanovaleric acid) and 2,2′-azobis (methylpropionic acid), benzoyl peroxide, lauroyl peroxide, di-t-butyl peroxide, cumene hydro Examples thereof include organic peroxides such as peroxides, which can be appropriately selected and used according to the monomer 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, particularly preferably 150,000 to 1,000,000, and further preferably 200,000 to 800,000. If the weight average molecular weight is too small, the toughness and cohesive force of the obtained pressure-sensitive adhesive layer tend to be lowered, and the transferability, holding force and shear strength after curing tend to be lowered. Further, if the weight average molecular weight is too large, the viscosity tends to be too high, resulting in increased scaling during polymerization, reduced compatibility with the epoxy compound (B), and reduced handleability. ..

  The degree of dispersion [weight average molecular weight (Mw) / number average molecular weight (Mn)] of the acrylic resin (A) is preferably 10 or less, particularly preferably 7 or less, and further preferably 5.5 or less. is there. If the dispersity is too high, the cohesive force tends to decrease. The lower limit of the degree of dispersion is usually 1.

The weight average molecular weight of the acrylic resin (A) is a weight average molecular weight in terms of standard polystyrene molecular weight, and is high performance liquid chromatography (manufactured by Japan Waters, "Waters 2695 (main body)" and "Waters 2414 (detector)". )), Column: Shodex GPC KF-806L (exclusion limit molecular weight: 2 × 10 ⁷ , separation range: 100 to 2 × 10 ⁷ , theoretical plate number: 10,000 plates / piece, packing material: styrene-divinylbenzene The polymer and the filler particle size: 10 μm) are used by connecting three in series, and the number average molecular weight can also be measured by the same method. The dispersity can be obtained from the measured values of the weight average molecular weight and the number average molecular weight.

  The glass transition temperature (Tg) of the acrylic resin (A) needs to be 0 ° C. or higher. Among them, the temperature is preferably 10 to 250 ° C, particularly preferably 15 to 200 ° C, and further preferably 20 to 180 ° C. If the glass transition temperature is too low, the shear strength after curing tends to decrease, and if it is too high, the tack before curing tends to decrease.

  The refractive index of the acrylic resin (A) is usually 1.440 to 1.600. For such a refractive index, it is preferable to reduce the difference in the refractive index of the members to be laminated, because the optical loss at the member interface will be small.

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

<Epoxy compound (B)>
Examples of the epoxy compound (B) used in the present invention include monofunctional epoxy compounds and polyfunctional epoxy compounds having two or more epoxy groups. These compounds may be used alone or in combination of two or more kinds. Then, from the viewpoint that the shear strength after curing tends to be high, it is preferable to include an epoxy compound having two or more epoxy groups.

  Examples of the monofunctional epoxy compound include alkyl glycidyl ether, alkoxy glycidyl ether, phenol glycidyl ether, EO (ethylene oxide) modified phenol glycidyl ether, and allyl glycidyl ether.

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

Furthermore, trifunctional epoxy compounds such as glycerol triglycidyl ether, trimethylolpropane triglycidyl ether, isocyanuric acid triglycidyl and its derivatives, and pentaerythritol triglycidyl ether;
4-functional epoxy compounds such as pentaerythritol tetraglycidyl ether, diglycerol tetraglycidyl ether, and ditrimethylolpropane tetraglycidyl ether;
Pentafunctional epoxy compounds such as polyglycerol pentaglycidyl ether, pentaerythritol pentaglycidyl ether, dipentaerythritol pentaglycidyl ether;
Sorbitol hexaglycidyl ether: a hexafunctional epoxy compound such as dipentaerythritol hexaglycidyl ether;
Other polyfunctional epoxy compounds such as polyglycidyl ether, phenol novolac type epoxy compounds and cresol novolac type epoxy compounds;
Etc.
Among these, a bifunctional or higher functional epoxy compound is preferable, and a trifunctional or higher functional epoxy compound is more preferable.

  The epoxy compound (B) preferably contains an epoxy compound which is liquid at 25 ° C., from the viewpoint of excellent balance of tackiness, holding power, tack, etc. of the adhesive layer before curing.

  When a liquid epoxy compound is used as the epoxy compound (B), its viscosity is preferably 100 to 30000 mPa · s / 25 ° C., and particularly 120 to 15000 mPa · s / 25 ° C. Is more preferable. If the viscosity is too high, the tack when the adhesive layer is formed tends to decrease, and if it is too low, the cohesive force when the adhesive layer is formed tends to decrease.

  Further, the weight average molecular weight of the epoxy compound (B) (according to the above-mentioned measuring method, the same applies hereinafter) is preferably 150 to 50,000, more preferably 250 to 30,000, and particularly preferably 300 to 10,000. If the molecular weight is too low, volatilization at high temperature or white smoke tends to occur, and if it is too high, the compatibility with the acrylic resin tends to decrease.

  Further, the content of the epoxy compound (B) needs to be 40 to 250 parts by weight, and particularly 50 to 200 parts by weight, based on 100 parts by weight of the acrylic resin (A). Is more preferable, and further more preferably 60 to 160 parts by weight. If the content of the epoxy compound (B) with respect to the acrylic resin (A) is too low, the tackiness of the tacky adhesive decreases and the handling property decreases, or the adhesiveness when the members are attached and cured. If it is too much, the holding power of the adhesive will tend to decrease.

<Crosslinking agent (C) for acrylic resin (A)>
Examples of the cross-linking agent (C) (hereinafter, simply referred to as “cross-linking agent (C)”) used as a cross-linking agent for the acrylic resin (A) include, for example, isocyanate-based cross-linking agents, aziridine-based cross-linking agents, and melamine-based cross-linking agents. , Aldehyde-based crosslinking agents, and metal chelate-based crosslinking agents. The compounds used as the epoxy compound (B) are excluded.

  Examples of the above-mentioned 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, tetra Xylylene diisocyanate compounds such as methyl xylylene diisocyanate; aromatic isocyanate compounds such as 1,5-naphthalene diisocyanate and triphenylmethane triisocyanate; hexamethylene diisocyanate, isophorone diisocyanate, and these isocyanate compounds and trimethylolpropane Examples thereof include adducts with polyol compounds, and burettes and isocyanurates of these polyisocyanate compounds.

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

  Furthermore, examples of the melamine-based cross-linking agent include hexamethoxymethylmelamine, hexaethoxymethylmelamine, hexapropoxymethylmelamine, hexabutoxymethylmelamine, hexapentyloxymethylmelamine, hexahexyloxymethylmelamine, and melamine resin. Be done.

  Examples of the aldehyde cross-linking agent include glyoxal, malondialdehyde, succindialdehyde, maleindialdehyde, glutardialdehyde, formaldehyde, acetaldehyde, benzaldehyde and the like.

  And as the metal chelate-based cross-linking agent, for example, acetylacetone or acetoacetyl ester coordination compound of polyvalent metal such as aluminum, iron, copper, zinc, tin, titanium, nickel, antimony, magnesium, vanadium, chromium, zirconium. Etc.

  The cross-linking agent (C) may be used alone or in combination of two or more kinds. Among the above-mentioned cross-linking agents (C), the isocyanate-based cross-linking agents are preferably used, in particular, from the viewpoint of improving the adhesion to the base material and the reactivity with the acrylic resin (A), among them. In particular, tolylene diisocyanate-based cross-linking agents and hexamethylene diisocyanate-based cross-linking agents are preferably used because they have excellent holding power and adhesive properties when used as a tacky adhesive.

  The content of the cross-linking agent (C) is preferably 0.1 to 30 parts by weight, more preferably 1 to 25 parts by weight, and particularly preferably 2. to 100 parts by weight of the acrylic resin (A). 5 to 20 parts by weight. When the content ratio of the cross-linking agent (C) to the acrylic resin (A) is within the above range, the cohesive adhesive tends to have particularly excellent holding power and transferability.

  The acrylic pressure-sensitive adhesive composition of the present invention contains the above-mentioned essential components acrylic resin (A), epoxy compound (B) and cross-linking agent (C). It is preferable that the curing agent (D) that reacts with the epoxy compound (B) (hereinafter, simply referred to as “curing agent (D)”) is contained because it can be efficiently cured when it is used as an adhesive.

<Curing agent (D)>
Examples of the curing agent (D) include amines, polyamides, imidazoles, polymercaptan curing agents, and acid anhydrides. These may be used alone or in combination of two or more. Among the above curing agents (D), dicyandiamide, which is an amine compound, and organic acid hydrazide are preferable, in particular, in view of excellent storage stability when used as an adhesive and shear strength during curing, and organic acid hydrazide is preferable. Of these, adipic acid hydrazide is particularly preferable because it is excellent in curing rate and shear strength after curing.

  The curing agent (D) may be liquid or solid, but is solid in terms of storage stability when used as a tacky adhesive and pot life of the tacky adhesive composition. Further, it is preferable that the coating film is dispersed and contained in a powder state in that the coating film becomes smooth and the adhesive area with the member increases when curing and the shear strength after curing increases. preferable. When powder is used as the curing agent (D), the particle size of the powder should be set to be 1.2 times or less the film thickness when the adhesive layer is formed. Is preferable, and it is more preferable that the amount is 1 time or less.

  When the curing agent (D) is used, its content is preferably 10 to 100 parts by weight, and particularly 15 to 80 parts by weight, based on 100 parts by weight of the epoxy compound (B). It is more preferably 25 to 50 parts by weight and most preferably 25 to 50 parts by weight. If the content ratio of the curing agent (D) to the epoxy compound (B) is less than the above range, the curing rate tends to be slow or the curing temperature tends to be high. There is a tendency that streaks are generated during the work and the pot life of the adhesive composition is shortened.

  The adhesive composition of the present invention may contain various optional components other than the above curing agent (D) as long as the effects of the present invention are not impaired. Hereinafter, those optional components will be described.

<Other optional ingredients>
Other 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, phenol resin, aliphatic petroleum resin, and oil. Tackifiers such as aromatic petroleum resins and styrene resins; fillers; antioxidants; UV absorbers; silane coupling agents; crosslinking accelerators such as ionic compounds, peroxides, urethanization catalysts, acetylacetone, etc. And various additives such as a crosslinking retarder.

  Further, in addition to the above-mentioned additives, a small amount of impurities and the like contained in the raw materials for manufacturing the constituent components of the acrylic pressure-sensitive adhesive composition may be contained.

  In the adhesive composition of the present invention, the acrylic resin (A), the epoxy compound (B), the crosslinking agent (C), and, if necessary, the curing agent (D) and other optional components are mixed. Can be obtained.

  The mixing method of these components is not particularly limited, and various methods such as a method of mixing each component at once or a method of mixing any components and then mixing the remaining components at once or sequentially Can be adopted.

  The pressure-sensitive adhesive composition of the present invention can be made into a pressure-sensitive adhesive by crosslinking an acrylic resin (A) with a crosslinking agent (C), and a pressure-sensitive adhesive layer made of this pressure-sensitive adhesive. A pressure-sensitive adhesive sheet can be obtained by laminating and forming a base material such as a plastic film.

  In addition, the adhesive / adhesive sheet is preferably a substrateless double-sided sheet in which separators (release sheets) are laminated on both sides of the adhesive / adhesive layer, from the viewpoint of easy handling.

  As the method for producing the adhesive / bonding sheet, for example, a separator or a substrate is coated with the adhesive / adhesive composition, dried, and then a separator (if applied to the separator, a separator having a different peeling force) is bonded. However, a method of performing treatment by at least one of room temperature (non-heating state) and aging in a heating state can be mentioned.

  The aging treatment is carried out in order to balance the sticky physical properties of the pressure-sensitive adhesive as the reaction time of the chemical cross-linking of the acrylic resin (A) and the cross-linking agent (C). Is usually room temperature (20 ° C. ± 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. I'll do it.

  At the time of applying the adhesive composition, it is preferable to dilute the adhesive composition with a solvent and apply it. The dilution concentration of the active ingredient is preferably 5 to 65% by weight, particularly preferably The concentration is 20 to 55% by weight. In addition, the solvent is not particularly limited as long as it can dissolve 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 solvents such as Among these, ethyl acetate is preferably used in terms of solubility, drying property, price and the like.

  The viscosity of the diluted adhesive composition is preferably 500 to 15000 mPa · s / 25 ° C, more preferably 1000 to 10000 mPa · s / 25 ° C. If the viscosity is too low, when a component having a high specific gravity is used, the component tends to settle.

  In addition, examples of the method for applying the adhesive composition include roll coating, die coating, gravure coating, comma coating, and screen printing.

  And the thickness of the adhesive layer in the obtained adhesive sheet is preferably 5 to 250 μm, particularly preferably 25 to 200 μm, and further preferably 50 to 175 μm. If the pressure-sensitive adhesive layer is too thin, the thickness accuracy tends to decrease or the pressure-sensitive adhesive force tends to decrease, and if it is too thick, the pressure-sensitive adhesive layer protrudes from the end when the pressure-sensitive adhesive sheet is rolled. Tend to

  The gel fraction of the adhesive layer produced by the above method is preferably 10 to 90% by weight, and particularly preferably 15 to 70% by weight from the viewpoint of adhesion to a substrate, reworkability and holding power. %, More preferably 20 to 60% by weight. If the gel fraction of the tacky-adhesive layer is too low, the cohesive force will be low, and the members will tend to shift when the tacky-adhesive is cured. Sufficient adhesion between the adhesive layer and the member interface cannot be obtained, and the shear strength after curing tends to decrease.

  The gel fraction is a measure of the degree of crosslinking (degree of curing), and is calculated by the following method, for example. That is, the tacky-adhesive agent is collected by picking from a tacky-adhesive sheet having a tacky-adhesive layer formed on the surface of a base material, etc., and the tacky-adhesive agent is wrapped in a 200-mesh SUS wire mesh and kept at 23 ° C. By immersing in the adjusted ethyl acetate for 24 hours, the weight percentage of the insoluble adhesive component remaining in the wire net to the weight of the adhesive layer before immersion in ethyl acetate is taken as the gel fraction.

  In the present invention, the adhesive layer is hardened by heating and the adhesive strength is increased. As the above heating conditions, the heating temperature is preferably 100 to 250 ° C, more preferably 120 to 200 ° C, and particularly preferably 130 to 185 ° C. If the temperature is too low, the curing time becomes long and the workability tends to decrease, and if it is too high, the epoxy compound tends to volatilize or ignite. The heating time is preferably 5 to 180 minutes, more preferably 30 to 120 minutes, and particularly preferably 45 to 90 minutes. If the time is too short, the shear strength tends to decrease, and if it is too long, the workability tends to decrease.

  And, the ratio of the shear strength after curing (MPa) to the shear strength before curing (MPa) is preferably 10 or more in order to balance the adhesive property before curing with the shear strength and durability after curing. It is preferably 20 or more, particularly preferably 100 or more.

  The pressure-sensitive adhesive layer of the present invention has the excellent characteristics that it has excellent transferability and holding power in the state before curing and exhibits high shear strength in the state after curing. Therefore, it can be suitably used for various applications such as building materials, in-vehicle parts, electronic parts, semiconductor manufacturing processes, member encapsulation, aviation parts, sports goods and the like.

  The adhesive / adhesive sheet having this adhesive / adhesive layer can be simply peeled off by separating the separator covering the surface of the adhesive / adhesive layer and adhering the adhesive / adhesive layer surface to the target member surface. Since the adhesive layer can be transferred to, it is very convenient to work.

  And, a laminate formed by laminating other members via the adhesive / adhesive layer has a high holding force before the adhesive / adhesive layer is cured, and exhibits high shear strength after curing. It is of excellent quality without being easily displaced or peeled off.

  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 as long as the gist thereof is not exceeded. In the examples, "part" and "%" mean weight basis.

<Acrylic resin (A)>
Seven types of acrylic resins (A-1 to 3, A'-1 to 4) shown in Table 1 below were prepared according to conventionally known procedures. The acrylic resin (A-1) will be described in detail as an example.
[Preparation of acrylic resin (A-1)]
A 4-neck round bottom flask equipped with a reflux condenser, a stirrer, a nitrogen gas blowing port, and a thermometer was charged with 72 parts of ethyl acetate, 24 parts of methyl ethyl ketone, and azobisisobutyronitrile (AIBN) as a polymerization initiator. After charging 0.036 part and heating the flask to reach an internal temperature of the boiling point, 74.5 parts of methyl acrylate (a1), 20 parts of methyl methacrylate, 5 parts of 2-hydroxyethyl acrylate (a1), and acrylic acid (a1) 0 A mixed solution of 0.5 part, 4 parts of ethyl acetate and 0.036 part of a polymerization initiator was added dropwise over 2 hours.
While continuing the reaction thereafter, a polymerization initiator (AIBN) was added twice and reacted for 7 hours, and then diluted with ethyl acetate to obtain an acrylic resin (A) solution (solid content concentration 38.0%, viscosity 13500 mPa · s / 25 ° C., acrylic resin (A): weight average molecular weight (Mw) 402,000, dispersity (Mn / Mn) 3.3) were obtained.

<Epoxy compound (B)>
Three types of epoxy compounds (B-1 to 3) shown in Table 2 below were prepared.

<Crosslinking agent (C)>
The following were used as the crosslinking agent (C).
(C-1): Adduct of tolylene diisocyanate and trimethylolpropane (Tosoh Corp., Coronate L55E)

<Curing agent (D)>
The following were used as the curing agent (D).
(D-1): adipic acid hydrazide (Mitsubishi Chemical Corporation ADH)

<Examples 1 to 8 and Comparative Examples 1 to 7>
The above components were blended according to Tables 3 and 4 described below, and the solid content concentration was adjusted to a range of 30 to 60% using ethyl acetate to obtain a pressure-sensitive adhesive composition.

Using the obtained pressure-sensitive adhesive composition, a pressure-sensitive adhesive sheet [I] for a sample was prepared according to the procedure described below, and its transferability, holding power, and shear strength after curing were evaluated. The evaluation method and evaluation criteria for each item are as described below.
The results are also shown in Tables 3 and 4 below.

<Sample: Preparation of Adhesive Sheet [I]>
The pressure-sensitive adhesive composition is applied to a heavy release silicone separator (SP PET 03 38BU manufactured by Mitsui Tohcello Co., Ltd.) having a thickness of 38 μm using a comma coater so that the thickness after drying will be 50 μm, and 100 ° C. × 3 minutes Dried. Then, a light-peeling silicone separator (SPPET01 38BU manufactured by Mitsui East Cello Co., Ltd.) having a thickness of 38 μm was attached to the surface of the dried tacky-adhesive layer to produce a tacky-adhesive sheet [I] (light-peeling silicon separator / viscous sheet). Adhesive layer /
Heavy release silicone separator).

<Transferability>
The adhesive / bonding sheet [I] has a width of 25 mm and a length of 100 mm so as to include the ends of the adhesive / adhesive layer.
After being cut into strips, the light release silicone separator was stripped off and laminated on a polyethylene terephthalate (PET) film (Torel mirror T60) having a thickness of 100 μm using a 2 kg roller. After that, when the heavy release silicone separator was peeled off, it was observed whether the adhesive layer could be transferred onto the PET film cleanly, and evaluated according to the following criteria.
O: It was transferred nicely.
Δ: Tear separation occurred on the adhesive sheet.
X: Almost no transfer was possible.

<Holding power>
The light release silicone separator of the adhesive / bonding sheet [I] is peeled off, transferred to a PET film, cut into 25 mm × 25 mm, the heavy release silicone separator is peeled off, and the adhesive / bonding agent layer side is polished. After being adhered to a SUS plate and allowed to stand for 30 minutes under the condition of 23 ° C. × 50% RH, a load of 1 kg was applied under the condition of 40 ° C. according to the measuring method of the holding force of JIS Z 0237. The deviation was evaluated. The evaluation criteria are as follows.
○ ・ ・ ・ No deviation in 24 hours △ ・ ・ ・ Displacement in 24 hours × ・ ・ ・ Drop in 24 hours

<Shear strength after curing>
The adhesive / bonding sheet [I] was cut into a size of 25 mm × 12.5 mm and transferred to a SUS plate. An SUS plate of the same size is attached to the opposite side of the transferred SUS plate, the attached portion is fixed with a clip, and cured at 140 ° C for 1 hour, and then under the condition of 23 ° C x 50% RH, AUTO Graph AG-X Plus. (Shimadzu) was used to measure the shear strength (MPa) at a speed of 5 mm / min. The evaluation criteria are as follows.
◎ ... 15 MPa or more ◯ ... 10 MPa or more and less than 15 MPa Δ ... 5 MPa or more and less than 10 MPa × ... 5 MPa or less

From the above results, it is understood that all of the products of Examples 1 to 8 have excellent transferability and holding power, and also have excellent shear strength after curing.
On the other hand, the products of Comparative Examples 1 to 7 which do not satisfy any of the requirements of the present invention have a low evaluation of any of transferability, holding force and shear strength, and are inferior in performance to the products of Examples 1 to 8. It turns out to be a thing.

  The pressure-sensitive adhesive composition of the present invention is excellent in transferability and holding power in a state before curing, and exhibits high shear strength in a state after curing, so that it is used in various applications, for example, for building materials and automotive parts. It is suitable for adhesive / bonding applications for electronic parts, semiconductor manufacturing processes, member encapsulation, aviation parts, and sports equipment.

Claims (9)

A pressure-sensitive adhesive composition containing an acrylic resin (A), an epoxy compound (B), and a cross-linking agent (C) of the acrylic resin (A) (excluding the epoxy compound (B)). hand,
The acrylic resin (A) is a polymer of a polymerization component containing the acryloyl group-containing monomer (a1) in an amount of 33% by weight or more with respect to the entire polymerization component, and has a glass transition temperature of 0 ° C. or higher.
Content of the said epoxy type compound (B) is 40-250 weight part with respect to 100 weight part of said acrylic resin (A), The adhesive composition characterized by the above-mentioned.   The acrylic resin (A) is a polymer of a polymerization component further containing as a polymerization component a functional group-containing monomer containing at least one monomer selected from a hydroxyl group-containing monomer and a carboxy group-containing monomer. The pressure-sensitive adhesive composition according to claim 1.   The adhesive composition according to claim 1 or 2, wherein the epoxy compound (B) is a liquid epoxy compound at 25 ° C.   The pressure-sensitive adhesive composition according to any one of claims 1 to 3, further comprising a curing agent (D) that reacts with the epoxy compound (B).   An adhesive / adhesive comprising the adhesive / adhesive composition according to claim 1 crosslinked.   The adhesive according to claim 5, which is cured by heating at 100 to 250 ° C.   The adhesive / bonding agent according to claim 6, wherein the ratio of the shear strength (MPa) after curing to the shear strength (MPa) before curing is 10 or more.   An adhesive / adhesive sheet comprising an adhesive / adhesive layer made of the adhesive / adhesive according to claim 5.   A layered product in which a tacky-adhesive layer made of the tacky-adhesive according to any one of claims 5 to 7 and another member are stacked.