JP2019151837A - Adhesive composition for hard-to-bond adherend, adhesive for hard-to-bond adherend and adhesive tape for hard-to-bond adherend - Google Patents

Abstract

To provide an adhesive composition for a hard-to-bond adherend that is strongly bonded to a hard-to-bond adherend such as ethylene propylene diene rubber (EPDM), butyl rubber (IIR), chloroprene rubber (CR), styrene-butadiene rubber (SBR), thermoplastic polyolefin rubber and modified asphalt and has a high holding power.SOLUTION: An adhesive composition for a hard-to-bond adherend contains an acrylic resin (A) obtained by the copolymerization of a copolymerization component (a) containing a terminal carboxy group-containing monomer (a1) represented by general formula (1) and a (meth) acrylic acid (a2). [formula] CH=CR-CO-O-(R-COO-)H (1) (where, Ris hydrogen or a methyl group, Ris a saturated aliphatic group, an unsaturated aliphatic, aromatic, saturated alicyclic, or divalent unsaturated alicyclic hydrocarbon, n is a positive number of 1 or more).SELECTED DRAWING: None

Description

  The present invention relates to a pressure-sensitive adhesive composition for a hardly-adhered adherend, and more specifically, a highly polar adherend, a low-polar adherend, a rubber-based hardly-adhered adherend, particularly ethylene propylene diene rubber ( The present invention relates to a pressure-sensitive adhesive composition for difficult-to-adhere adherends having high adhesion to EPDM, and a pressure-sensitive adhesive for difficult-to-adhere adherends and a pressure-sensitive adhesive tape for difficult-to-adhere adherends using the same.

  Conventionally, adhesives and adhesive tapes using acrylic resins are, for example, kraft tapes, OPP (Oriented Poly Propylene) tapes, cloth adhesive tapes and other packaging tapes, light packaging cellophane adhesive tapes, temporary fixing tapes, automobiles, etc. Foam tape, vibration damping sheet, flame retardant adhesive tape, double-sided adhesive tape, residential curing tape, soundproof seal, double-sided tape for fixing carpet, tape for temporary fixing, vinyl tape for electrical insulation, outdoor anti-corrosion tape, indoor display Tapes, anti-slip tapes, various masking tapes, various surface protection tapes, adhesive tapes for airtight waterproofing, medical emergency adhesive bandages, surgical tapes, adhesive bandages, electrical / electronic tapes, optical double-sided tapes, Wide range of surface protection film, semiconductor dicing tape, heat conduction tape, heat-resistant tape, conductive tape, etc. It has been used in developing.

  As acrylic resin used for the said adhesive and adhesive tape, the acrylic resin formed by copolymerizing alkyl (meth) acrylate as a main component is common. In addition, acrylic resins using a carboxy group-containing monomer as a copolymerization component in order to improve adhesion to an adherend are known.

  Furthermore, in order to improve adhesiveness with an adherend, it has been proposed to use an acrylic acid adduct having a specific structure as a carboxy group-containing monomer (see, for example, Patent Documents 1 to 3).

Japanese Patent Laid-Open No. 2-196879 JP 2008-127431 A JP 2014-40500 A

  However, in the disclosed technique of the above-mentioned Patent Document 1, by including a relatively large amount of a specific acrylic acid adduct as a copolymerization component, the adhesion to a high polarity adherend and a low polarity adherend is improved. However, polypropylene is specifically evaluated as a low-polarity adherend, and it is evaluated for difficult-adhesion adherends such as ethylene propylene diene rubber (EPDM), which is difficult to improve the adhesive strength. not.

  In the technique disclosed in Patent Document 2, an acrylic resin having an acid value of 1 to 50 mgKOH / g, a hydroxyl value of 10 to 60 mgKOH / g, and a number average molecular weight of 50,000 to 500,000, copolymerized with an acrylic acid adduct, In the pressure-sensitive adhesive composition containing an isocyanate compound, it is described that a pressure-sensitive adhesive composition excellent in stickiness / adhesive strength retention over time, moist heat resistance, heat resistance, and rework pressure-sensitive adhesive properties can be obtained. The content of the acrylic acid adduct is a relatively small content of 1% by weight with respect to the copolymer component, and this is insufficient in improving the adhesive strength. Moreover, the adherend in Patent Document 2 is an adhesive to a glass substrate or the like, and is different from an adherend that is hardly adhesive.

  In the technique disclosed in Patent Document 3, an acrylic resin (A) obtained using a (meth) acrylic acid alkyl ester, a (meth) acrylic monomer having a carboxy group, and a (meth) acrylic monomer having a hydroxyl group. ), A solvent (B) and a crosslinking agent (C), wherein the (meth) acrylic monomer having a carboxy group has 2 to 6 (meth) acrylic acids and carbonyl groups. In the case of containing a (meth) acrylic monomer having the above-mentioned range, it is described that a pressure-sensitive adhesive with little decrease in adhesive force and holding power can be obtained even in a high-temperature environment. The adhesive strength and holding power against the slag were not taken into consideration and were still not satisfactory.

In general, an adhesive tape using an acrylic resin exhibits excellent adhesion to a highly polar adherend, but it is difficult to adhere to a rubber-based adherend, particularly ethylene propylene diene rubber (EPDM). Such a low-polarity adherend does not exhibit sufficient adhesiveness.
From this, a polymer roof sheet material (for example, a sheet made of a hard-to-adhere member such as ethylene propylene diene rubber (EPDM), butyl rubber (IIR), chloroprene rubber (CR), thermoplastic polyolefin rubber, modified asphalt, and polychlorinated When using pressure-sensitive adhesive tapes for airtightness and waterproofing of seams such as sheets made of vinyl or chlorinated polyethylene, etc., pressure-sensitive adhesive tapes and asphalt using butyl rubber with high adhesion to these difficult-to-adhere substrates Adhesive tape using is used. However, adhesive tape using butyl rubber and adhesive tape using asphalt have poor durability and heat resistance, are weak against shearing force, and have low creep properties (retention force) under a certain stress. There are problems such as slippage. And since the tape using the conventional acrylic adhesive composition is inferior to the adhesiveness with respect to a difficult-to-adhere adherend, such as a polymer roof sheet material, it was hardly used. However, from the market, it has adhesiveness equivalent to adhesive tape using butyl rubber and adhesive tape using asphalt for difficult-to-adhere adherends such as polymer roof sheet materials, and the holding power is improved. A tape using an acrylic pressure-sensitive adhesive composition is desired.
In addition, the pressure-sensitive adhesive tape is strongly bonded to a low-polarity difficult-to-bond adherend such as EPDM, and a high holding force is required so that the sheet fixed with the tape does not shift.

  In view of this, in the present invention, against such difficult-to-adhere adherends such as ethylene propylene diene rubber (EPDM), butyl rubber (IIR), chloroprene rubber (CR), thermoplastic polyolefin rubber and modified asphalt. It is intended to provide a pressure-sensitive adhesive composition for difficult-to-adhere adherends having high holding power and, in particular, a pressure-sensitive adhesive composition useful for ethylene propylene diene rubber (EPDM). is there.

  However, as a result of intensive studies in view of such circumstances, the present inventors, as a result, in a pressure-sensitive adhesive composition using an acrylic resin, a specific terminal carboxy group-containing monomer and ( It has been found that when it contains (meth) acrylic acid, it becomes a pressure-sensitive adhesive composition that adheres firmly to a rubber-based adherend that is difficult to adhere, particularly to an adherend that is difficult to adhere such as EPDM. invention has been completed.

  That is, the present invention relates to an acrylic resin obtained by copolymerizing a terminal carboxyl group-containing monomer (a1) represented by the following general formula (1) and a copolymerization component (a) containing (meth) acrylic acid (a2). The pressure-sensitive adhesive composition for difficult-to-adhere adherends containing A) is the first gist.

[Formula] ^{_{CH 2 = CR 1 -CO-O-}} (R 2 -COO-) n H ··· (1)
(Where R ¹ is hydrogen or a methyl group, R ² is a saturated aliphatic, unsaturated aliphatic, aromatic, saturated alicyclic or divalent unsaturated alicyclic hydrocarbon, and n is a positive number of 1 or more. Indicates the number.)

  Furthermore, this invention makes the adhesive for hard-to-adhere adherends formed by bridge | crosslinking the adhesive composition for difficult-to-adhere adherends of the said 1st summary to a 2nd summary, and hardly adheres to the said 2nd summary. A third gist of the pressure-sensitive adhesive tape for difficult-to-adhere adherends, in which a pressure-sensitive adhesive for adherends is formed on a substrate.

  In the pressure-sensitive adhesive composition, it is generally known that the adhesive force is improved by using the terminal carboxyl group-containing monomer (a1) represented by the general formula (1) as a copolymerization component. However, since the terminal carboxy group-containing monomer (a1) is contained, there is a concern that the holding force or the like is usually decreased due to the increase in the distance between the crosslinking points. It was considered difficult to achieve both. However, in the present invention, in the case of using an adherend such as a rubber-based difficult adhesion adherent, particularly ethylene propylene diene rubber (EPDM), an acrylic having such a terminal carboxy group-containing monomer (a1) as a copolymerization component. It has been found that by using a resin, it becomes a pressure-sensitive adhesive composition having an excellent adhesive property without unexpectedly reducing the holding power.

The present invention provides an acrylic resin (A) obtained by copolymerizing a terminal carboxyl group-containing monomer (a1) represented by the following general formula (1) and a copolymerization component (a) containing (meth) acrylic acid (a2). Since it is a pressure-sensitive adhesive composition for difficult-to-adhere adherends, it has good adhesion to rubber-based difficult-to-adhere adherends, particularly adherents that are difficult to adhere such as EPDM. In addition, the holding power is also excellent. Therefore, it is useful as various pressure-sensitive adhesives and pressure-sensitive adhesive tapes used for difficult-to-adhere adherends, and in particular, can be suitably used as pressure-sensitive adhesive tapes for fixing EPDM sheets and the like used for buildings and the like.
[Formula] ^{_{CH 2 = CR 1 -CO-O-}} (R 2 -COO-) n H ··· (1)
(Where R ¹ is hydrogen or a methyl group, R ² is a saturated aliphatic, unsaturated aliphatic, aromatic, saturated alicyclic or divalent unsaturated alicyclic hydrocarbon, and n is a positive number of 1 or more. Indicates the number.)

And especially in this invention, when the said acrylic resin (A) is an acrylic resin formed by copolymerizing the copolymerization component (a) containing the following (a1)-(a4), it will adhere The adhesion to the body and the holding power can be further improved.
(A1) Terminal carboxyl group-containing monomer represented by the above general formula (1) 1 to 20% by weight
(A2) (Meth) acrylic acid 0.1 to 5% by weight
(A3) (meth) acrylate having 4 to 24 carbon atoms (excluding t-butyl (meth) acrylate) 55 to 97% by weight
(A4) At least one selected from the group consisting of (meth) acrylates having 1 to 3 carbon atoms, t-butyl (meth) acrylate, cyclic structure-containing monomers, and vinyl ester monomers having 3 to 10 carbon atoms. 11% by weight or less

  In the present invention, in particular, the (meth) acrylate (a3) having an alkyl group having 4 to 24 carbon atoms is a (meth) acrylate (a3-1) having an alkyl group having 4 to 7 carbon atoms, When the (meth) acrylate (a3-2) having an alkyl group having 8 to 24 carbon atoms is contained, the adhesion to the adherend can be further improved.

  Furthermore, among the present invention, in particular, the (meth) acrylate (a3-2) having an alkyl group having 8 to 24 carbon atoms of the (meth) acrylate (a3-1) having an alkyl group having 4 to 7 carbon atoms. When the content ratio with respect to is (a3-1) / (a3-2) = 1/99 to 85/15 in terms of weight ratio, the adhesion to the adherend can be further improved.

  And especially in this invention, content of the said (meth) acrylic acid (a2) with respect to 100 weight part of terminal carboxy-group containing monomers (a1) shown by the said General formula (1) is 10-400 weight part. If it exists, the adhesiveness with respect to a to-be-adhered body can be made more excellent.

  Further, in the present invention, in particular, when a hydroxyl group-containing monomer (a5) is further contained as the copolymer component (a), the adhesion to the adherend can be further improved.

  The pressure-sensitive adhesive for difficult-to-adhere adherends obtained by crosslinking the pressure-sensitive adhesive composition for difficult-to-adhere adherends can have better adhesion to the adherend.

The present invention is described in detail below.
In the present invention, “(meth) acryl” means acryl or methacryl, “(meth) acryloyl” means acryloyl or methacryloyl, and “(meth) acrylate” means acrylate or methacrylate. . The “acrylic resin” is a resin obtained by polymerizing a polymerization component containing at least one (meth) acrylate monomer.

  The pressure-sensitive adhesive composition for an hardly adherend adherend of the present invention contains an acrylic resin (A) obtained by copolymerizing a copolymer component (a) containing a specific monomer component.

<Acrylic resin (A)>
The acrylic resin (A) used in the present invention is obtained by copolymerizing a copolymer component (a) containing a terminal carboxy group-containing monomer (a1) represented by the following general formula (1) and (meth) acrylic acid (a2). It is made.

[(A1) component]
The component (a1) used in the present invention is a terminal carboxy group-containing monomer represented by the following general formula (1).

[Formula] ^{_{CH 2 = CR 1 -CO-O-}} (R 2 -COO-) n H ··· (1)
(Where R ¹ is hydrogen or a methyl group, R ² is a saturated aliphatic, unsaturated aliphatic, aromatic, saturated alicyclic or divalent unsaturated alicyclic hydrocarbon, and n is a positive number of 1 or more. Indicates the number.)

The hydrocarbon of R ² is preferably alkylene having 1 to 10 carbon atoms such as a methylene group, preferably 1 to 5 alkylene, phenyl or phenylene, and n is preferably 1 to 10, more preferably 1-5.

  The content ratio of the component (a1) is preferably 1 to 20% by weight, particularly 1.5 to 15% by weight, more preferably 2 to 8.5% by weight based on the entire copolymer component (a). % it is preferred that. If the content is too small, the adhesion to the hardly-adhered adherend tends to decrease, and if too much, the adhesion to the hardly-adhered adherend tends to decrease.

[(A2) component]
The content ratio of (meth) acrylic acid (a2) is preferably 0.1 to 5% by weight, particularly 0.5 to 4.5% by weight, based on the entire copolymer component (a). Is preferably 1 to 4% by weight. If the content is too small, the adhesion to the hardly-adhered adherend tends to decrease, and if too much, the adhesion to the hardly-adhered adherend tends to decrease.

  The content ratio of the component (a1) and the component (a2) is a weight ratio, and the component (a2) is usually 10 to 400 parts by weight, particularly 20 to 200 parts by weight with respect to 100 parts by weight of the component (a1). Parts, more preferably 25 to 100 parts by weight, especially 30 to 75 parts by weight. When the amount of the component (a2) is too small, the holding power tends to decrease, and when the amount is too large, the adhesion to the hardly adherend adherend tends to decrease.

  In the present invention, a (meth) acrylate having an alkyl group having 4 to 24 carbon atoms (excluding t-butyl (meth) acrylate) (a3) as the main component of the copolymer component (a) from the viewpoint of adhesiveness. ) preferably contains a. Further, from the viewpoint of adhesiveness, (meth) acrylate having 1 to 3 carbon atoms, t-butyl (meth) acrylate, cyclic structure-containing monomer, and vinyl having 3 to 10 carbon atoms as copolymerization component (a). It is preferable to contain at least one (a4) selected from the group consisting of ester monomers. .

[(A3) component]
The (meth) acrylate having an alkyl group having 4 to 24 carbon atoms (excluding t-butyl (meth) acrylate) (a3) is a (meth) acrylate having an alkyl group having 4 to 7 carbon atoms (a3). -1) and (meth) acrylate (a3-2) having an alkyl group having 8 to 24 carbon atoms are preferably contained.

  Examples of the (meth) acrylate (a3-1) having an alkyl group having 4 to 7 carbon atoms include n-butyl (meth) acrylate, isobutyl (meth) acrylate, n-hexyl (meth) acrylate, and the like. . Of these, n-butyl (meth) acrylate is preferred because it is easily available and economical.

  Examples of the (meth) acrylate (a3-2) having an alkyl group having 8 to 24 carbon atoms include 2-ethylhexyl (meth) acrylate, n-octyl (meth) acrylate, isooctyl (meth) acrylate, and isononyl (meta ) Acrylate, isodecyl (meth) acrylate, lauryl (meth) acrylate, tridecyl (meth) acrylate, isotridecyl (meth) acrylate, myristyl (meth) acrylate, isomyristyl (meth) acrylate, cetyl (meth) acrylate, stearyl (meth) Examples include acrylate, isostearyl (meth) acrylate, and behenyl (meth) acrylate. Of these, (meth) acrylates having an alkyl group having 8 to 12 carbon atoms are preferable in terms of low polarity and low glass transition temperature, and 2-ethylhexyl (meth) acrylate is particularly preferable.

  The content ratio of the component (a3) is preferably 55 to 97% by weight, particularly 70 to 95% by weight, more preferably 80 to 93% by weight, based on the entire copolymer component (a). It is preferred. When the content is too small, the adhesiveness to the hardly-adhered adherend tends to decrease, and when it is too large, the adhesiveness decreases and the holding power tends to decrease.

  The content ratio of the component (a3-1) to the component (a3-2) is a weight ratio of (a3-1) / (a3-2) = 1/99 to 85/15, particularly 2 / It is preferably 98 to 75/25, more preferably 3/97 to 70/30, and particularly preferably 5/95 to 60/40. When the content ratio of the component (a3-1) is too small, the holding power tends to decrease, and when it is too large, the adhesiveness to the hardly-adhered adherend tends to decrease.

[(A4) component]
The component (a4) is selected from the group consisting of (meth) acrylates having 1 to 3 carbon atoms, t-butyl (meth) acrylate, cyclic structure-containing monomers, and vinyl ester monomers having 3 to 10 carbon atoms. At least one kind. Especially, the (meth) acrylate which has a C1-C3 alkyl group is preferable.

  Examples of the (meth) acrylate having an alkyl group having 1 to 3 carbon atoms include methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, and the like. Of these, methyl (meth) acrylate and ethyl (meth) acrylate are preferred.

  The cyclic structure-containing monomer is usually an acrylic monomer having a substituent containing a cyclic structure. For example, N- (meth) acryloylmorpholine, N-vinylpyrrolidone, N-vinylcaprolactam, vinylpyrrolidone, N- ( Heterocycle-containing (meth) acrylates having a morpholine ring such as (meth) acryloylpiperidine and N- (meth) acryloylpyrrolidine, piperidine rings, pyrrolidine rings, piperazine rings and the like, and phenyl (meth) acrylate, phenoxyethyl (meth) ) Acrylate, phenyldiethylene glycol (meth) acrylate, 2-hydroxy-3-phenoxypropyl (meth) acrylate, tetrahydrofurfuryl (meth) acrylate, benzyl (meth) acrylate, dicyclopentenyl (meth) acrylate Dicyclopentenyloxyethyl (meth) acrylate, dicyclopentanyl (meth) acrylate, nonylphenol polyethylene glycol (meth) acrylate, nonylphenoxypolyethylene glycol (meth) acrylate, isobornyl (meth) acrylate, biphenyloxyethyl (meth) ) Acrylate, others, styrene, α-methylstyrene and the like. Among these, a heterocyclic-containing (meth) acrylate having a morpholine ring, particularly N- (meth) acryloylmorpholine is preferable from the viewpoint of availability and safety because of a good balance of various physical properties.

  Examples of the vinyl ester monomer having 3 to 10 carbon atoms include vinyl formate, vinyl acetate, vinyl propionate, vinyl valelate, vinyl butyrate, vinyl isobutyrate, and vinyl pivalate. Among these, vinyl acetate is preferable because it is easily available.

  The content of the above (a4) is preferably 11% by weight or less, particularly 10% by weight or less, more preferably 8% by weight or less, particularly 5% by weight, based on the entire copolymer component (a). % by is preferably less. When there is too much content of (a4) component, there exists a tendency for the adhesiveness with respect to a to-be-adhered body to fall. In addition, the minimum of content of the (a4) component in a copolymerization component (a) is 1 weight% normally.

[(A5) component]
The copolymer component (a) used in the present invention preferably further contains a hydroxyl group-containing monomer (a5) as a copolymer component.

  Examples of the hydroxyl group-containing monomer (a5) include 2-hydroxyethyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, 5-hydroxypentyl (meth) acrylate, 6-hydroxyhexyl (meth) acrylate, 8- Hydroxyalkyl esters of (meth) acrylic acid such as hydroxyoctyl (meth) acrylate, caprolactone-modified monomers such as caprolactone-modified 2-hydroxyethyl (meth) acrylate, and oxyalkylene modifications such as diethylene glycol (meth) acrylate and polyethylene glycol (meth) acrylate Monomer, primary hydroxyl group-containing monomer such as 2-acryloyloxyethyl-2-hydroxyethylphthalic acid; 2-hydroxypropyl (meth) acrylate, 2-hydroxybutyrate Can be mentioned 2,2-dimethyl 2-hydroxyethyl (meth) tertiary hydroxyl group-containing monomers such as acrylate; (meth) acrylate, secondary hydroxyl group-containing monomers such as 3-chloro-2-hydroxypropyl (meth) acrylate.

  Among these, a primary hydroxyl group-containing monomer is preferable from the viewpoint of excellent reactivity with a crosslinking agent, and 2-hydroxyethyl (meth) acrylate and 4-hydroxybutyl (meth) acrylate are particularly preferable.

  The hydroxyl group-containing monomer (a5) is useful because it serves as a crosslinking point when a crosslinking agent is blended, and is particularly effective when an isocyanate crosslinking agent is used as the crosslinking agent. In such a case, it is preferable that it is 0.01 to 5 weight% normally with respect to the whole copolymerization component (a), Especially 0.05 to 3 weight%, Furthermore, it is preferable that it is 0.05 to 2 weight%. When the amount of the component (a5) is too small, the holding power tends to decrease, and when the amount is too large, the adhesiveness to the hardly adherend adherend tends to decrease.

<Other polymerizable monomer (a6)>
In the present invention, if necessary, other polymerizable monomer (a6) may be used. Examples of the other polymerizable monomer (a6) include an acetoacetyl group-containing monomer, an isocyanate group-containing monomer, and a glycidyl group-containing monomer. And functional group-containing monomers such as amino group-containing monomers and amide group-containing monomers, and other copolymerizable monomers.

  Examples of the acetoacetyl group-containing monomer include 2- (acetoacetoxy) ethyl (meth) acrylate and allyl acetoacetate.

  Examples of the isocyanate group-containing monomer include 2-acryloyloxyethyl isocyanate, 2-methacryloyloxyethyl isocyanate, and alkylene oxide adducts thereof.

  Examples of the glycidyl group-containing monomer include glycidyl (meth) acrylate, allyl glycidyl (meth) acrylate, and the like.

  Examples of the amino group-containing monomer include monomers having an ethylenically unsaturated double bond and an amino group (unsubstituted or substituted amino group), such as aminomethyl (meth) acrylate, aminoethyl (meth) acrylate. N-alkylaminoalkyl (meth) acrylates such as aminopropyl (meth) acrylate, aminoisopropyl (meth) acrylate, and (meth) acrylate N- (t-butyl) aminoethyl ) Monosubstituted amino group-containing (meth) acrylic acid ester such as acrylic acid ester; (meth) acrylic acid N, N-dimethylaminoethyl, (meth) acrylic acid N, N-diethylaminoethyl, (meth) acrylic acid N, N, N-dialkylaminoalkyl (meth) acrylic acid such as N-dimethylaminopropyl Di-substituted amino group-containing (meth) acrylic acid esters such as ter; dialkylaminoalkyl (meth) acrylamides such as N, N-dimethylaminopropyl (meth) acrylamide; quaternized salts of these amino group-containing monomers; Amino group-containing styrenes such as p-aminostyrene; styrenes having a dialkylamino group such as 3- (dimethylamino) styrene and dimethylaminomethylstyrene; N, N-dimethylaminoethyl vinyl ether, N, N-diethylaminoethyl vinyl ether Dialkylaminoalkyl vinyl ethers such as allylamine, 4-diisopropylamino-1-butene, trans-2-butene-1,4-diamine, 2-vinyl-4,6-diamino-1,3,5-triazine, etc. can give.

  Examples of the amide group-containing monomer include monomers having an ethylenically unsaturated double bond and an amide group (group having an amide bond), such as (meth) acrylamide; N-methyl (meth) acrylamide, N-ethyl. (Meth) acrylamide, N-propyl (meth) acrylamide, N-isopropyl (meth) acrylamide, Nn-butyl (meth) acrylamide, N-isobutyl (meth) acrylamide, Ns-butyl (meth) acrylamide, N -T-butyl (meth) acrylamide, N-hexyl (meth) acrylamide, diacetone (meth) acrylamide, N, N'-methylenebis (meth) acrylamide, N- (1,1-dimethyl-3-oxobutyl) (meta ) N-alkyl (meth) acrylic such as acrylamide N, N-dimethyl (meth) acrylamide, N, N-diethyl (meth) acrylamide, N, N-dipropyl (meth) acrylamide, N, N-diisopropyl (meth) acrylamide, N, N-di (n- Butyl) (meth) acrylamide, N, N-diisobutyl (meth) acrylamide, N, N-di (s-butyl) (meth) acrylamide, N, N-di (t-butyl) (meth) acrylamide, N, N -Dipentyl (meth) acrylamide, N, N-dihexyl (meth) acrylamide, N, N-diheptyl (meth) acrylamide, N, N-dioctyl (meth) acrylamide, N, N-diallyl (meth) acrylamide, N, N -N, N-dialkyl (meth) acrylamide such as ethylmethylacrylamide; N, N-dimethyl Dialkylaminoalkyl (meth) acrylamides such as aminopropyl (meth) acrylamide; substituted amide groups such as N-vinylacetamide, N-vinylformamide, (meth) acrylamide ethylethyleneurea, (meth) acrylamide-t-butylsulfonic acid Monomer; hydroxyl group-containing (meth) acrylamide such as N-methylol (meth) acrylamide, N-hydroxyethyl (meth) acrylamide, N-methylolpropane (meth) acrylamide; N-methoxymethyl (meth) acrylamide, N- (n Examples include alkoxy group-containing (meth) acrylamides such as (butoxymethyl) (meth) acrylamide; quaternized salts of these amide group-containing monomers.

  Examples of the other copolymerizable monomers include 2-methoxyethyl (meth) acrylate, 2-ethoxyethyl (meth) acrylate, methoxydiethylene glycol (meth) acrylate, ethoxydiethylene glycol (meth) acrylate, and methoxypolyethylene glycol (meth). Monomers containing alkoxy groups or oxyalkylene groups such as acrylate, polypropylene glycol mono (meth) acrylate; acrylonitrile, methacrylonitrile, vinyl stearate, vinyl chloride, vinylidene chloride, alkyl vinyl ether, vinyl toluene, itaconic acid dialkyl ester, Dialkyl fumarate, allyl alcohol, acrylic chloride, methyl vinyl ketone, allyltrimethylammonium chloride , Dimethylallyl vinyl ketone, and the like.

  The other polymerizable monomer (a6) is contained in the copolymer component (a) to such an extent that the effects of the present invention are not hindered in order to adjust the physical properties according to the application.

  Thus, the above components (a1) to (a2), preferably (a3), (a4), and if necessary, (a5), (a6) are further polymerized as a copolymerization component (a) for acrylic. system resin (A) is obtained. In addition, each of these components (a1) to (a6) may be used alone or in combination of two or more.

  In the above polymerization, production by solution polymerization is preferable because the acrylic resin (A) can be produced safely and stably with an arbitrary monomer composition.

  Such solution polymerization is carried out according to a conventional method, for example, by mixing or dropping the copolymerization components (a) and (a6) and a polymerization initiator in an organic solvent, in a reflux state or at 50 to 98 ° C. And may be polymerized for 0.1 to 20 hours.

  Examples of such polymerization initiators include azo-based polymerization initiators such as azobisisobutyronitrile and azobisdimethylvaleronitrile, which are ordinary radical polymerization initiators, benzoyl peroxide, lauroyl peroxide, and di-t-butyl peroxide. Specific examples include peroxide-based polymerization initiators such as cumene hydroperoxide. These may be used alone or in combination of two or more.

  The weight average molecular weight of the acrylic resin (A) thus obtained is usually 100,000 to 5,000,000, preferably 300,000 to 1,500,000, particularly preferably 500,000 to 900,000. When the weight average molecular weight is too small, the durability performance tends to decrease, and when it is too large, the adhesive strength tends to decrease.

  The degree of dispersion (weight average molecular weight / number average molecular weight) of the acrylic resin (A) is preferably 20 or less, particularly preferably 15 or less, more preferably 10 or less, and particularly preferably 7 or less. preferable. When the degree of dispersion is too high, the durability performance of the pressure-sensitive adhesive layer is lowered, and foaming or the like tends to occur. The lower limit of the degree of dispersion is usually 1.1 from the viewpoint of production limit.

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 a high performance liquid chromatograph (manufactured by Waters, Japan, “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 / pack, packing material: styrene-divinylbenzene copolymer, (Particle size: 10 μm) is used in series, and the same method can be used for the number average molecular weight.

  The glass transition temperature (Tg) of the acrylic resin (A) is usually −80 to 10 ° C., particularly preferably −70 to −10 ° C., more preferably −65 to −20 ° C., and the glass transition temperature. If it is too high, tack tends to be insufficient, and if it is too low, heat resistance tends to decrease.

  The glass transition temperature (Tg) is a value calculated by applying the glass transition temperature and the weight fraction when each monomer constituting the acrylic resin (A) is a homopolymer to the following Fox equation. .

  Here, the glass transition temperature when the monomer constituting the acrylic resin (A) is a homopolymer is usually measured by a differential scanning calorimeter (DSC) by a method based on JIS K7121-1987 or JIS K6240. Value and catalog value are used.

  The acrylic resin (A) is usually subjected to viscosity adjustment with a solvent or the like, and used for coating as an acrylic resin (A) solution. The viscosity of the acrylic resin (A) solution is preferably 500 to 20000 mPa · s, particularly preferably 1000 to 18000 mPa · s, and more preferably 2000 to 15000 mPa · s from the viewpoint of ease of handling. If the viscosity is too high, the fluidity tends to be lowered and difficult to handle, and if it is too low, the application of the pressure-sensitive adhesive tends to be difficult.

  The solvent is not particularly limited as long as it dissolves the acrylic resin (A). For example, ester solvents such as methyl acetate, ethyl acetate, methyl acetoacetate and ethyl acetoacetate, acetone, methyl ethyl ketone, A ketone solvent such as methyl isobutyl ketone, an aromatic solvent such as toluene and xylene, an alcohol solvent such as methanol, ethanol, and propyl alcohol can be used. Among these, ethyl acetate and methyl ethyl ketone are preferably used from the viewpoints of solubility, drying properties, and price. These solvents may be used alone or in combination of two or more.

  The viscosity of the acrylic resin (A) solution can be measured according to the JIS K5400 (1990) 4.5.3 rotational viscometer method.

<Crosslinking agent (B)>
The pressure-sensitive adhesive composition for difficult-to-adhere adherends of the present invention preferably contains a crosslinking agent (B) in addition to the acrylic resin (A) from the viewpoint of adhesiveness and holding power.

  The crosslinking agent (B) reacts with the functional group in the acrylic resin (A) to form a crosslinked structure. For example, an epoxy crosslinking agent, an isocyanate crosslinking agent, an aziridine crosslinking agent, a melamine Examples include a crosslinking agent, an aldehyde-based crosslinking agent, an amine-based crosslinking agent, and a metal chelate-based crosslinking agent. Among these, it is preferable to use an epoxy-based cross-linking agent from the viewpoint that both adhesion to various adherends and holding power can be balanced. Further, it is preferable to use an isocyanate-based cross-linking agent in order to obtain an effect that is excellent in stability over time as a pressure-sensitive adhesive tape even in a high-temperature environment and further has excellent adhesiveness.

  Examples of the epoxy crosslinking agent include 1,3-bis (N, N′-diglycidylaminomethyl) cyclohexane, N, N, N ′, N′-tetraglycidyl-m-xylylenediamine, and ethylene glycol diene. Examples thereof include glycidyl ether, 1,6-hexanediol diglycidyl ether, trimethylolpropane diglycidyl ether, diglycidyl aniline, diglycidyl amine and the like.

  The isocyanate-based crosslinking agent contains two or more isocyanate groups. For example, aromatic polyisocyanates such as tolylene diisocyanate, diphenylmethane diisocyanate, xylylene diisocyanate, aliphatic polyisocyanates such as hexamethylene diisocyanate, isophorone diisocyanate, Alicyclic polyisocyanates such as hydrogenated diphenylmethane diisocyanate and the like, and these biurets, isocyanurates, and low molecular active hydrogen-containing compounds such as ethylene glycol, propylene glycol, neopentyl glycol, trimethylolpropane, castor oil and the like The adduct body etc. which are reaction materials of this are mention | raise | lifted.

  Examples of the aziridine-based crosslinking agent include diphenylmethane-4,4′-bis (1-aziridinecarboxamide), trimethylolpropane tri-β-aziridinylpropionate, and tetramethylolmethanetri-β-aziridini. Lupropionate, toluene-2,4-bis (1-aziridinecarboxamide), triethylenemelamine, bisisophthaloyl-1- (2-methylaziridine), tris-1- (2-methylaziridine) phosphine And trimethylolpropane tri-β- (2-methylaziridine) propionate.

  Examples of the melamine crosslinking agent include, for example, melamine, amino group-containing methylol melamine obtained by condensing melamine and formaldehyde, methylol melamine derivatives such as imino group-containing methylol melamine, hexamethylol melamine, methylol melamine derivatives, methyl alcohol and butyl Examples thereof include partially or fully alkylated methylol melamine partially or completely etherified by reaction with a lower alcohol such as alcohol, alkylated methylol melamine such as imino group-containing moiety or fully alkylated methylol melamine, and the like.

  Examples of the aldehyde-based crosslinking agent include formaldehyde, acetaldehyde, propionaldehyde, butyraldehyde, glyoxal, glutaraldehyde, dialdehyde starch, hexamethylenetetramine, 1,4-dioxane-2,3-diol, 1,3-bis. Aldehyde compounds that liberate aldehydes in aqueous solutions such as (hydroxymethyl) -2-imidazolidine, dimethylolurea, N-methylolacrylamide, urea formalin resin, melamine formalin resin, etc., or benzaldehyde, 2-methylbenzaldehyde, 4-methyl Aromatic aldehyde compounds such as benzaldehyde, p-hydroxybenzaldehyde, m-hydroxybenzaldehyde and the like can be mentioned.

  Examples of the amine-based crosslinking agent include 4,4'-methylene-bis (2-chloroaniline) (hereinafter abbreviated as "MOCA"), modified MOCA, and diethyltoluenediamine.

  Examples of the metal chelate-based crosslinking agent include chelate compounds whose metal atoms are aluminum, zirconium, titanium, zinc, iron, tin and the like, and aluminum chelate compounds are preferable from the viewpoint of performance. Examples of the aluminum chelate compound include diisopropoxy aluminum monooleyl acetoacetate, monoisopropoxy aluminum bis oleyl acetoacetate, monoisopropoxy aluminum monooleate monoethyl acetoacetate, diisopropoxy aluminum monolauryl acetoacetate, diisopropoxy Examples thereof include aluminum monostearyl acetoacetate and diisopropoxyaluminum monoisostearyl acetoacetate.

  The crosslinking agent (B) may be used alone or in combination of two or more.

  Content of the said crosslinking agent (B) is 0.01-5 weight part normally with respect to 100 weight part of acrylic resin (A), Especially 0.01-4 weight part, Furthermore, 0.02-3 it is preferred parts by weight. If the content is too small, the holding power tends to decrease, and if it is too large, the adhesion to various adherends tends to decrease.

  Among the cross-linking agents (B), it is preferable to use the epoxy-based cross-linking agent from the viewpoint that both adhesion to the adherend and holding power can be balanced. In the case of using the epoxy crosslinking agent, the content of the crosslinking agent (B) is usually 0.005 to 1 part by weight, particularly 0.01 to 100 parts by weight with respect to 100 parts by weight of the acrylic resin (A). The amount is preferably 0.5 parts by weight, more preferably 0.02 to 0.1 parts by weight. If the content is too small, the holding power tends to decrease, and if it is too large, the adhesion to the adherend tends to decrease.

  Moreover, it is preferable to use the said isocyanate type crosslinking agent among the said crosslinking agents (B) from the point which a coupling | bonding is strong and is excellent in durability. The content of the crosslinking agent (B) in the case of using the isocyanate crosslinking agent is usually 0.1 to 5 parts by weight, particularly 0.1 to 0.1 parts by weight with respect to 100 parts by weight of the acrylic resin (A). It is preferably 3 parts by weight, more preferably 0.3 to 2 parts by weight. When the content is too small, the holding power tends to decrease, and when the content is too large, the adhesion to a low-polarity adherend tends to decrease.

<Tackifier (C)>
The tackifier (C) is used for further exhibiting good physical properties of the acrylic resin (A), and is preferably contained in the pressure-sensitive adhesive composition for difficult-to-adhere adherends of the present invention. . Examples of the tackifier (C) include resins that are compatible with the acrylic resin (A), such as rosin resins, terpene resins, xylene resins, phenol resins, coumarone resins, petroleum resins, and the like. It is done. These tackifiers (C) can be used alone or in combination of two or more. Of these, rosin resins, terpene resins, and petroleum resins are preferable.

  Examples of the rosin resin include a rosin ester resin obtained by esterifying a raw material rosin obtained by hydrogenation (hydrogenation), disproportionation, dimerization, and acid addition with glycerin or pentaerythritol, or phenol. Added rosin phenol resin. Although any rosin resin is used, the good physical properties of the acrylic resin (A) are further exhibited. Among them, the raw material rosin is disproportionated and esterified with glycerin or pentaerythritol, and the softening point is 70 ° C. to Disproportionated rosin ester in the range of 130 ° C, polymerized rosin ester in which the raw material rosin is dimerized and esterified with pentaerythritol and the softening point is in the range of 110 ° C to 170 ° C, and phenol is added to the raw material rosin Rosin phenol having a softening point in the range of 120 to 160 ° C is preferred.

The terpene resin is a general term for compounds based on the isoprene rule represented by the molecular formula (C ₅ H ₈ ) _n , and as a tackifier (C) used in the present invention, a monoterpene (eg, α-pinene, β-pinene, limonene, etc.) as a raw material, and resins that are homo- or copolymerized with Friedel Kraft catalysts. Specifically, as a resin in which monoterpene is singly or copolymerized, for example, α-pinene resin, β-pinene resin, dipentene resin, terpene phenol resin, aromatic modified terpene resin or hydrogenated terpene resin obtained by hydrogenating these resins Etc. Among these, the terpene phenol resin is preferable because it has good compatibility with the acrylic resin (A), and any terpene phenol resin further exhibits the good physical properties of the acrylic resin (A). Those having a softening point in the range of 90 ° C. to 170 ° C. and a hydroxyl value in the range of 20 to 250 mgKOH / g are preferred, and those having a softening point in the range of 100 ° C. to 150 ° C. and a hydroxyl value in the range of 50 to 150 mgKOH / g are preferred.

  The petroleum-based resin is obtained, for example, by polymerization of C4-C5 and C9-C11 fraction monomers generated by thermal decomposition of naphtha or the like, and further hydrogenation. Group (C5) petroleum resin, aromatic (C9) petroleum resin, hydrogenated petroleum resin and the like. Whichever petroleum resin is used, the good physical properties of the acrylic resin (A) are further exhibited. Among them, those having a softening point in the range of 90 ° C. to 130 ° C. are preferable. It is preferable to use a copolymer resin with a group monomer.

  The content of the tackifier (C) is usually 1 to 50 parts by weight, particularly 5 to 30 parts by weight, and further 5 to 20 parts by weight with respect to 100 parts by weight of the acrylic resin (A). Preferably, an appropriate amount is blended according to the required physical properties.

  Further, the pressure-sensitive adhesive composition for difficult-to-adhere adherends of the present invention includes, as other components, resin components other than the acrylic resin (A), acrylic monomers, and polymerization prohibition, as long as the effects of the present invention are not impaired. Various additives such as additives, antioxidants, corrosion inhibitors, crosslinking accelerators, radical generators, peroxides, UV absorbers, plasticizers, pigments, stabilizers, fillers, radical scavengers, flame retardants, Metal and resin particles can be blended. In addition to the above, a small amount of impurities contained in the raw materials for producing the constituent components of the pressure-sensitive adhesive composition for difficult-to-adhere adherends may be contained.

  The content of the other components is preferably 5 parts by weight or less, particularly preferably 1 part by weight or less, and further preferably 0.5 parts by weight or less with respect to 100 parts by weight of the acrylic resin (A). . When there is too much this content, compatibility with acrylic resin (A) will fall, and there exists a tendency for durability to fall. However, with the above contents of pigments, fillers, flame retardants, metals and resin particles, etc., additives that do not exhibit their effects, etc., are appropriate in a range that does not impair the effects of the present invention while exhibiting the effects of the additives. there is a case to be added.

As described above, the pressure-sensitive adhesive composition for difficult-to-adhere adherends of the present invention preferably includes a crosslinking agent (B) and a tackifier (C) in addition to the acrylic resin (A), and further if necessary. And other components.
The pressure-sensitive adhesive composition for difficult-to-adhere adherends of the present invention can be obtained by mixing the above components. Moreover, the adhesive for difficult-to-adhere adherends of the present invention is obtained by crosslinking the adhesive composition for hardly-adhered adherends. The pressure-sensitive adhesive for difficult-to-adhere adherends can be suitably used as the pressure-sensitive adhesive layer of the pressure-sensitive adhesive tape for difficult-to-adhere adherends of the present invention.

<Adhesive tape for difficult-to-adhere adherends>
The pressure-sensitive adhesive tape for difficult-to-adhere adherends of the present invention contains a pressure-sensitive adhesive for difficult-to-adhere adherends obtained by crosslinking the above-mentioned pressure-sensitive adhesive composition for adherends as a pressure-sensitive adhesive layer. is there. Specifically, the above-mentioned adhesive composition for difficult-to-adhere adherends is dissolved in a solvent such as ethyl acetate so that the solid content concentration is 10 to 70% by weight. A pressure-sensitive adhesive composition solution is prepared, and this solution is applied to a substrate and dried to obtain a pressure-sensitive adhesive tape for a hardly adherent adherend.

  About the manufacturing method of this pressure-sensitive adhesive tape, a publicly known method for manufacturing a pressure-sensitive adhesive tape may be used. For example, a pressure-sensitive adhesive is applied to one surface of a substrate and dried, and then released onto the surface of the formed pressure-sensitive adhesive layer. It can be produced by a method of stacking a liner or a method of applying and drying a pressure-sensitive adhesive on one surface of a release liner and stacking a substrate on the surface of the formed pressure-sensitive adhesive layer. Among these, a method of applying and drying an adhesive on one surface of the release liner and stacking the substrate on the surface of the formed adhesive layer is preferable from the viewpoint of handling and the like.

  Further, the base material preferably has hand cutting properties, and the surface of the base material having hand cutting properties is, for example, physical treatment such as corona discharge treatment or plasma treatment, chemical treatment such as undercoating treatment, etc. The known and usual surface treatment may be appropriately performed.

  The base material is not particularly limited as long as it is a conventionally known base material. For example, a rayon cloth, a cotton cloth, a polyester cloth, a cloth made of a blended yarn of rayon and polyester, a non-woven fabric, a flat yarn cloth, a flat Examples thereof include a laminated film in which a plastic film is laminated on a yarn cloth. Among these, those containing flat yarn cloth are preferred from the viewpoint of high tensile strength in the longitudinal direction.

  The flat yarn cloth is a woven fabric made by weaving a flat yarn, which is made of polyethylene or polypropylene called flat yarn, cut into strips and stretched to give strength. A flat yarn that intersects vertically and horizontally is fixed by heat fusion so as not to be misaligned.

  Examples of the release liner include polyolefin resins such as polyethylene, polyester resins such as polyethylene terephthalate, plastic films made of plastics such as vinyl acetate resins, polyimide resins, fluorine resins, and cellophane; kraft paper, Japanese paper, etc. Paper, rubber sheets made of natural rubber, butyl rubber, etc .; foam sheets made by foaming polyurethane, polychloroprene rubber, etc .; metal foils such as aluminum foil and copper foil; and composites thereof. Moreover, surface treatments, such as a corona treatment, may be given to the single side | surface or both surfaces.

  Examples of the release liner include glassine paper, kraft paper, clay-coated paper laminated with a film such as polyethylene, paper coated with a resin such as polyvinyl alcohol or an acrylate copolymer, polyester or polypropylene. And the like obtained by coating a fluororesin or a silicone resin as a release agent on a synthetic resin film or the like.

Among these, a paper release liner is preferable in that it is easily teared by hand, and a paper release liner having a base paper weight of 40 to 120 g / m ² , preferably 50 to 80 g / m ² is particularly preferable. preferable. Furthermore, the thickness of the release liner is preferably 40 to 180 μm, particularly 60 to 140 μm, and more preferably 80 to 120 μm. If the thickness is too thin, the production tends to be difficult, such as wrinkling at the time of winding, and if it is too thick, the hand cutting property tends to decrease.

  As a coating apparatus used when applying an adhesive to one surface of the substrate or the release liner, a commonly used coating apparatus may be used. For example, a roll knife coater, a die coater, a roll coater , Bar coater, gravure roll coater, reverse roll coater, dipping, blade coater and the like.

Moreover, it is preferable that the thickness after drying of an adhesive layer is 5-200 micrometers, Most preferably, it is 10-150 micrometers, More preferably, it is 15-130 micrometers.
When the thickness is too thick, it tends to be difficult to apply the pressure-sensitive adhesive, and when it is too thin, there is a tendency that sufficient adhesive strength cannot be obtained.

  Moreover, the single-sided adhesive tape may be sufficient as the adhesive tape for difficult-to-adhere adherends of this invention, and a double-sided adhesive tape may be sufficient as it. Further, the pressure-sensitive adhesive layers of the double-sided pressure-sensitive adhesive tape may be the same pressure-sensitive adhesive layer or may be pressure-sensitive adhesive layers having different compositions.

  In addition, when laminating release liners on the adhesive layer of double-sided pressure-sensitive adhesive tapes, each release liner should be selected so that the release liners laminated on both sides have different peel forces in order to improve workability. It is preferred. For example, when the release liner that is lightly peeled from the release liner on the surface side to be bonded next is selected as the release force of the release liner on the surface side to be bonded next, the workability is improved.

  The drying conditions are that the solvent and residual monomer in the pressure-sensitive adhesive are dried and removed during drying, and when the crosslinking agent (B) is used, the functional group and crosslinking agent (B) of the acrylic resin (A). As long as they can react with each other to form a crosslinked structure. As drying conditions, 60-120 degreeC and about 1-5 minutes are preferable, for example. After drying, aging (aging) is performed with the pressure-sensitive adhesive layer sandwiched between sheet-like substrates, and the crosslinking reaction can further proceed.

The pressure-sensitive adhesive tape for difficult-to-adhere adherends of the present invention may be in the form of a roll, may be in a single wafer state, or may be processed into various shapes.
And when the pressure-sensitive adhesive tape for difficult-to-adhere adherend is a double-sided pressure-sensitive adhesive tape and is in a sheet-fed state, it is preferable that release liners are provided on both surfaces of the two pressure-sensitive adhesive layers. In this case, it is preferable that the release liner is provided only on one surface of the two pressure-sensitive adhesive layers.

  Thus, the pressure-sensitive adhesive tape for difficult-to-adhere adherends of the present invention can be obtained, but the pressure-sensitive adhesive tape for difficult-to-adhere adherends of the present invention is also capable of adhering to adherends and substrates that lower the adhesive performance. There is no decrease in the thickness, and it has a good holding power. Furthermore, when a base material having hand cutting properties is used as the base material, it can be easily cut by hand at any position without using a tape cutter or the like in the tape width direction. It is particularly useful as a tape.

  As the adhesive strength of the adhesive layer in the adhesive tape for difficult-to-adhere adherends, the 180 ° peel strength is usually 1 to 100 N / 25 mm with respect to the adherend used.

Among them, test plates of ethylene propylene diene rubber (EPDM), chloroprene rubber (CR), natural rubber (NR), styrene butadiene rubber (SBR), and butyl rubber (IIR), which are adherends that are difficult to adhere, are used. When used, the 180 ° peel strength is preferably 10 N / 25 mm or more, particularly preferably 15 N / 25 mm or more, and more preferably 17 N / 25 mm or more. The upper limit is usually about 100 N / 25 mm.
When a SUS304 steel test plate having a relatively high polarity is used as the adherend, the 180 ° peel strength is preferably 25 N / 25 mm or more, particularly preferably 30 N / 25 mm or more, and more preferably 35 N / It is 25 mm or more. The upper limit is usually about 100 N / 25 mm.

  The adhesive strength varies depending on the composition (material), surface state (surface roughness), treatment (cleaning) conditions, etc. of the adherend, and is not limited to the above range of peel strength.

  The measurement of such adhesive strength is a value measured according to JIS Z0237. Specifically, it can be measured by the method described in Examples below.

  When the test piece is a double-sided pressure-sensitive adhesive tape, the adhesive surface not to be tested is covered with a polyethylene terephthalate film having a nominal thickness of 25 μm as defined in JIS C 2318 (Toray Industries, Lumirror S10). The adhesive force of the target adhesive surface can be measured.

  Further, as the holding force of the pressure-sensitive adhesive layer in the pressure-sensitive adhesive tape for difficult-to-adhere adherends of the present invention, when measured by the method described in Examples below, it is particularly preferable that the test piece does not fall from the test plate after 24 hours. Preferably, even if the test piece falls within 24 hours, the holding time is preferably 80 minutes or more, and more preferably 150 minutes or more.

  Further, the gel fraction of the pressure-sensitive adhesive layer in the pressure-sensitive adhesive tape for difficult-to-adhere adherends is preferably 10 to 70% by weight, particularly preferably 20 to 60% by weight from the viewpoint of adhesiveness and holding power. Yes, more preferably 25 to 50% by weight. If the gel fraction is too low, the holding force on the adherend tends to decrease, and if it is too high, the adhesion to the adherend tends to decrease.

  The gel fraction is a measure of the degree of crosslinking (curing degree), and is calculated, for example, by the following method. That is, the pressure-sensitive adhesive layer was collected from the pressure-sensitive adhesive tape for difficult-to-adhere adhesion by picking, and this pressure-sensitive adhesive layer was wrapped with a 200 mesh SUS metal mesh and immersed in toluene maintained at 23 ° C. for 48 hours. The weight percentage of the remaining insoluble pressure-sensitive adhesive component is defined as the gel fraction.

  In addition, in adjusting the gel fraction of an adhesive to the said range, it is achieved by adjusting the kind and quantity of a crosslinking agent (B).

  In addition, the adhesive tape for difficult-to-adhere adherends of the present invention preferably has a high tensile strength, so that when sticking to difficult-to-adhere adherends etc., it is pulled so as not to be distorted or peeled off for position correction Necessary strength is required. The tensile strength of the pressure-sensitive adhesive tape for difficult-to-adhere adherend is usually 20 N / 25 mm or more, more preferably 30 N / 25 mm or more, and particularly preferably 50 N / 25 mm or more. The upper limit of the tensile strength is usually 250 N / 25 mm. The double-sided pressure-sensitive adhesive tape having a high tensile strength can be achieved by using a base material having a tensile strength equal to or higher than that of the target pressure-sensitive adhesive tape.

  Examples of the adhesive tape for difficult-to-adhere adherends of the present invention include packaging tapes such as craft tape, OPP tape, and cloth adhesive tape, cellophane adhesive tape for light packaging, foaming tape for automobiles, vibration damping sheet, flame-retardant adhesive tape , Residential curing tape, soundproof seal, double-sided tape for fixing carpet, vinyl tape for electrical insulation, outdoor anticorrosion tape, indoor display tape, anti-slip tape, airtight waterproof adhesive tape, medical emergency adhesive plaster, etc. Surgical tapes, adhesive bandages, electrical / electronic tapes, optical double-sided tapes, semiconductor dicing tapes, thermal conductive tapes, heat-resistant tapes, conductive tapes, etc., can be used in a wide range of applications.

  The pressure-sensitive adhesive tape can be used, for example, in a housing structure, a member thereof, a gap between members, and the like. The adherend is not particularly limited, but when used as an adhesive tape, for example, ethylene propylene diene rubber (EPDM), butyl rubber (IIR), chloroprene rubber (CR), natural rubber (NR) ), Styrene-butadiene rubber (SBR), polyvinyl chloride, chlorinated polyethylene, thermoplastic polyolefin rubber, and sheet materials made of difficult-to-adhere adherends such as modified asphalt.

  EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to the following examples unless it exceeds the gist. In the examples, “parts” and “%” mean weight basis.

First, various acrylic resins (A) were prepared as follows.
The weight average molecular weight, the degree of dispersion, the glass transition temperature, and the viscosity of the acrylic resin (A) were measured according to the method described above.

<Acrylic resin (A)>
Prior to the production of the acrylic resin (A), the following were prepared as the copolymer component (a) used for the production.
Component (a1) Terminal carboxyl group-containing monomer represented by the following general formula (1) CH ₂ = CR ¹ —CO—O— (R ² —COO—) _n H (1)
In the general formula (1), R ¹ is hydrogen, R ² is an ethylene chain, and n is 1 to 5
Component (a2) Acrylic acid (AAc)
(A3-1) component n-butyl acrylate (BA)
Component (a3-2) 2-ethylhexyl acrylate (2EHA)
(A-4) Component Methyl acrylate (MA)
Component (a-5) 2-Hydroxyethyl methacrylate (HEMA)

In addition, about the said (a1) component, "Sypomer H" by Solvay Nikka Co., Ltd. was used.
Cypomer H is a mixture containing 75% of compound (a1) in which R ^{1 in} formula (1) is hydrogen, R ² is an ethylene chain, and n = 1 to 5 and 25% of acrylic acid (a2) ( Hereinafter, Cypomer H is referred to as “β-CEA”, and the compounds of the general formula (1) contained in Cypomer H may be collectively referred to as “CAO”).

[Production of acrylic resin (A-1)]
In a reactor equipped with a thermometer, a stirrer and a reflux condenser, Cypomer H 5 parts [CAO (a1) 3.75 parts, acrylic acid (a2) 1.25 parts], n-butyl acrylate (a3-1) 26.7 parts, 2-ethylhexyl acrylate (a3-2) 65.2 parts, methyl acrylate (a4) 3 parts, 2-hydroxyethyl methacrylate (a5) 0.1 part, ethyl acetate 55 parts, and polymerization initiator A 0.15 part of azobisisobutyronitrile was added, the temperature was increased with stirring, the mixture was polymerized at the reflux temperature of ethyl acetate for 7 hours, diluted with ethyl acetate, and an acrylic resin (A -1) A solution was obtained.
The obtained acrylic resin (A-1) had a weight average molecular weight of 550,000, a dispersity of 4.3, and a glass transition temperature of -61 ° C.

[Production of Acrylic Resins (A-2) to (A-4) and (A′-1)]
In the production of the acrylic resin (A-1), the acrylic resin (A-2) to (A-4) and (A) are prepared in the same manner except that the composition of the copolymerization component is changed as shown in Table 1 below. A solution of '-1) was obtained.

<Crosslinking agent (B)>
The following were prepared as a crosslinking agent (B).
B-1: Epoxy-based crosslinking agent: Tetrad C (1,3-bis (N, N-diglycidylaminomethyl) cyclohexane) manufactured by Mitsubishi Gas Chemical Company, Inc.

<Tackifier (C)>
The following were prepared as tackifiers.
C-1: disproportionated rosin ester: manufactured by Arakawa Chemical Industries, super ester A-100 (glycerin ester of disproportionated rosin, softening point 95-105 ° C.)
C-2: Petroleum resin: Mitsui Chemicals, FTR6100 (copolymerization resin of styrene monomer and aliphatic monomer, softening point 95 ° C.)

<Example 1>
About acrylic resin (A-1) solution prepared and prepared as described above, 0.04 of crosslinker (B-1) [epoxy crosslinker (Tetrad C)] is added to 100 parts of its solid content. Part, 15 parts of tackifier (C-1) [disproportionated rosin ester (superester A-100)]. Then, it prepared so that solid content concentration might be 40% with ethyl acetate, it stirred until it became uniform, and the solution of the adhesive composition for difficult-to-adhere adherends was obtained.

<Examples 2 to 5 and Comparative Example 1>
In Example 1 above, the composition of the pressure-sensitive adhesive composition for difficult-to-adhere adherends was changed in the same manner as shown in Table 2 below. A solution of the agent composition was obtained.

  About the obtained adhesive composition for difficult-to-adhere adherends of Examples 1 to 5 and Comparative Example 1, adhesive tapes for difficult-to-adhere adherends were produced as follows, and the following evaluations were performed. The evaluation results are shown in Table 2 below.

[Preparation of adhesive tape for difficult-to-adhere adherends]
The thickness of the adhesive composition for difficult-to-adhere adherends prepared as described above is 110 μm after drying with respect to the release surface of a paper release liner [SS-70-SBX (manufactured by Shinomura Chemical Co., Ltd.)]. Then, coating was performed using an applicator, followed by drying at 80 ° C. for 5 minutes, and flat yarn (Diatex Corp., thickness 130 μm) was bonded. Then, the heat aging process was performed for 7 days in a 40 degreeC dryer, and the adhesive tape for difficult-to-adhere adherends was produced.

<Gel fraction>
The release liner made of paper is peeled off from the obtained adhesive tape for difficult-to-adhere adherends, the adhesive is picked from the surface of the adhesive layer, wrapped with a 200 mesh wire mesh made of SUS, and then kept in toluene kept at 23 ° C. for 48 hours. The weight percentage of the insoluble adhesive component that was immersed and then remained in the wire mesh was taken as the gel fraction.
Gel fraction (%)
= Weight of insoluble adhesive component (g) / Weight of adhesive component before immersion (g) x 100

<180 ° peel strength>
The adhesive tape was cut into a width of 25 mm and a length of 150 mm to prepare a test piece. In addition, ethylene propylene diene rubber (EPDM) (manufactured by Engineering Test Service, standard test version EPDM-70) chloroprene rubber (CR) (manufactured by Nippon Test Panel, standard test plate), natural rubber (NR) ( Methanol test plates made by Nippon Test Panel Co., Ltd., styrene butadiene rubber (SBR) (Japan Test Panel Co., standard test plate) and butyl rubber (IIR) (Japan Test Panel Co., standard test plate) with methanol After the surface was washed, it was left to stand overnight in an atmosphere of 23 ° C. and 50% RH. The paper release liner was peeled off from the test piece, and the pressure-sensitive adhesive layer of the test piece was pressed against the test plate by reciprocating a 2 kg weight roller at a pressing speed of 10 mm / s. After crimping, leave it in an atmosphere of 23 ° C. and 50% RH for 30 minutes, turn the play part of the test piece 180 °, peel off 30 mm, and put the test plate on the lower chuck of the peel strength tester in the same atmosphere. The ends of the test pieces were respectively fixed to the upper chuck, and the adhesive tape was peeled off from the adherend at a peeling angle of 180 ° and a speed of 300 mm / min. The peel strength was measured and evaluated as follows.
〔Evaluation criteria〕
A: Peel strength is 17 N / 25 mm or more B: Peel strength is 15 N / 25 mm or more and less than 17 N / 25 mm C: Peel strength is less than 15 N / 25 mm

<Retention force>
The adhesive tape was cut into a width of 25 mm and a length of 75 mm to prepare a test piece. An EPDM test plate was used as the adherend. The test piece is attached to a roller weighing 2 kg so that the contact area between the adhesive layer of the test piece from which the paper release liner is peeled and the test plate is 25 mm wide × 25 mm long. The pressure was reciprocated twice at 10 mm / s. Further, the portion of the test piece where the adhesive was exposed was folded. After crimping, the sample was allowed to stand for 30 minutes in an environment of 23 ° C. and 50% RH, then moved to an environment of 40 ° C. and allowed to stand for 20 minutes. A weight of 1000 g was attached so that the test piece hangs vertically on the test plate, and then the time when the test piece dropped in an environment of 40 ° C. was measured, and the holding time was evaluated as follows.
〔Evaluation criteria〕
A: 150 minutes or more B: 80 minutes or more, less than 150 minutes C: Less than 80 minutes

<Comparative Example 2>
In Example 1, the same evaluation was performed by changing the pressure-sensitive adhesive tape to a commercially available asphalt-based pressure-sensitive adhesive tape often used for fixing a rubber-based hardly-adhered adherend.

<Comparative Example 3>
In Example 1, the pressure-sensitive adhesive tape was changed to a commercially available butyl rubber-based pressure-sensitive adhesive tape often used for fixing a rubber-based hardly-adhered adherend, and the same evaluation was performed.

  From the results of Table 2 above, all of the examples of the present invention have high peel strength even on difficult-to-adhere adherends such as EPDM, CR, NR, SBR, and IIR. It was firmly bonded. Moreover, the holding power with respect to EPDM was high and it was excellent in the creep property under fixed stress.

On the other hand, Comparative Example 1 had low peel strength and poor adhesion to difficult-to-adhere adherends such as EPDM, CR, NR, SBR, and IIR.
Further, Comparative Examples 2 and 3 had a high peel strength with respect to difficult-to-adhere adherends such as EPDM, but had a low holding power and a poor creep property under a certain stress.

  That is, in the case of an adherend having a high polarity such as SUS, the selectivity of the acrylic resin is not required. It turns out that it has excellent adhesiveness by using the acrylic resin (A) obtained by copolymerizing the copolymerization component (a) containing the monomer (a1) and (meth) acrylic acid (a2). . In addition, the product of the example of the present invention has a significantly higher holding power than the pressure-sensitive adhesive tape using butyl rubber or the pressure-sensitive adhesive tape using asphalt, and has both excellent adhesiveness and high holding power.

  The pressure-sensitive adhesive composition for difficult-to-adhere adherends of the present invention is excellent in adhesion to rubber-based hardly-adhered adherends, particularly adherents that are difficult to adhere such as ethylene propylene diene rubber (EPDM). Therefore, packaging tape such as craft tape, OPP tape, cloth adhesive tape, cellophane adhesive tape for light packaging, foam tape for automobiles, vibration damping sheet, flame retardant adhesive tape, residential curing tape, soundproof seal, both sides for fixing carpet Tape, vinyl tape for electrical insulation, outdoor anticorrosion tape, indoor display tape, anti-slip tape, airtight waterproof adhesive tape, medical emergency adhesive bandage, surgical tape, adhesive bandage, tape for electrical and electronic equipment, It can be used for a wide range of applications as optical double-sided tape, semiconductor dicing tape, heat conductive tape, heat-resistant tape, conductive tape, and the like.

Claims (10)

It contains an acrylic resin (A) obtained by copolymerizing a terminal carboxyl group-containing monomer (a1) represented by the following general formula (1) and a copolymerization component (a) including (meth) acrylic acid (a2). A pressure-sensitive adhesive composition for difficult-to-adhere adherends.
[Formula] ^{_{CH 2 = CR 1 -CO-O-}} (R 2 -COO-) n H ··· (1)
(Where R ¹ is hydrogen or a methyl group, R ² is a saturated aliphatic, unsaturated aliphatic, aromatic, saturated alicyclic or divalent unsaturated alicyclic hydrocarbon, and n is a positive number of 1 or more. Indicates the number.) 2. The hardly adhesive adhesion according to claim 1, wherein the acrylic resin (A) is an acrylic resin obtained by copolymerizing a copolymer component (a) including the following (a1) to (a4): Body pressure-sensitive adhesive composition.
(A1) Terminal carboxyl group-containing monomer represented by the above general formula (1) 1 to 20% by weight
(A2) (Meth) acrylic acid 0.1 to 5% by weight
(A3) (meth) acrylate having 4 to 24 carbon atoms (excluding t-butyl (meth) acrylate) 55 to 97% by weight
(A4) At least one selected from the group consisting of (meth) acrylates having 1 to 3 carbon atoms, t-butyl (meth) acrylate, cyclic structure-containing monomers, and vinyl ester monomers having 3 to 10 carbon atoms. 11% by weight or less   The (meth) acrylate (a3) having an alkyl group having 4 to 24 carbon atoms is a (meth) acrylate (a3-1) having an alkyl group having 4 to 7 carbon atoms, and an alkyl group having 8 to 24 carbon atoms. The pressure-sensitive adhesive composition for difficult-to-adhere adherends according to claim 2, comprising (meth) acrylate (a3-2).   The content ratio of the (meth) acrylate (a3-1) having an alkyl group having 4 to 7 carbon atoms to the (meth) acrylate (a3-2) having an alkyl group having 8 to 24 carbon atoms is expressed by weight ratio ( The pressure-sensitive adhesive composition for difficult-to-adhere adherends according to claim 3, wherein a3-1) / (a3-2) = 1/99 to 85/15.   The content of the (meth) acrylic acid (a2) with respect to 100 parts by weight of the terminal carboxy group-containing monomer (a1) represented by the general formula (1) is 10 to 400 parts by weight. The pressure-sensitive adhesive composition for difficult-to-adhere adherends according to any one of 4.   The pressure-sensitive adhesive composition for difficult-to-adhere adherends according to any one of claims 1 to 5, further comprising a hydroxyl group-containing monomer (a5) as the copolymer component (a).   Furthermore, the tackifier (C) is contained, The adhesive composition for difficult-to-adhere adherends as described in any one of Claims 1-6 characterized by the above-mentioned.   A pressure-sensitive adhesive for difficult-to-adhere adherends, wherein the pressure-sensitive adhesive composition for difficult-to-adhere adherends according to any one of claims 1 to 7 is crosslinked.   A pressure-sensitive adhesive tape for difficult-to-adhere adherends, wherein the adhesive for hardly-adhered adherends according to claim 8 is formed on a substrate.   The pressure-sensitive adhesive composition for difficult-to-adhere adherends according to any one of claims 1 to 7, wherein the hardly-adhered adherend is ethylene propylene diene rubber.