JP2789236B2 - Active energy ray-curable pressure-sensitive adhesive for hot melt - Google Patents

Description

The present invention relates to an active energy ray-curable pressure-sensitive adhesive for hot melt, and more particularly to an acrylic (co) polymer having a specific molecular weight. A specific amount of one or more compounds selected from a group of compounds having a specific molecular weight range having two or more specific ethylenically unsaturated bonds in one molecule, one (meth) acryloyl group in one molecule and (poly) The present invention relates to an active energy ray-curable pressure-sensitive adhesive for hot melt, which comprises a specific amount of a compound containing an oxyalkylene chain and a specific amount of an antioxidant.

[Conventional technology and its problems]

Conventionally, many adhesives have been known for active energy ray-curable pressure-sensitive adhesives. However, these adhesives still have many problems that need to be solved.

For example, Japanese Patent Application Laid-Open No. Sho 50-136328 discloses that "alkyl acrylate (alkyl group having 3 to 10 carbon atoms) 50 to 100".
Parts by weight, 20-100 parts by weight of vinyl acetate, COOH, CN, CON on the side chain
H ₂ and is coated or impregnated with a copolymer composed mainly of vinyl monomer 3-15 parts by weight on a support sheet having a selected polar group from the group of derivatives thereof, which retain pressure sensitive adhesive properties Pressure-sensitive adhesive tape characterized by irradiating ionizing radiation within a range of from 3 to 35 Mrad to form an appropriate crosslink.

However, in order to impart sufficient cohesive force to the pressure-sensitive adhesive layer of the “pressure-sensitive adhesive tape” in the above proposal, it is generally necessary to irradiate a relatively high dose of ionizing radiation. In many cases, the pressure-sensitive adhesiveness of the agent layer is extremely reduced, and it is easy for the pressure-sensitive adhesive tape to maintain various properties such as heat resistance, pressure-sensitive adhesiveness, adhesive strength, and cohesive force in a well-balanced manner. is not. Further, if the irradiation dose of the ionizing radiation is too large, the “support sheet” may be deteriorated, and there is a problem that the material of the support sheet is limited by itself.

Furthermore, in order to use the above-mentioned copolymer as a hot-melt pressure-sensitive adhesive, the coating must be heated to a considerably high temperature in order to secure the coating viscosity.
Problems such as thermal deterioration are likely to occur. Further, when an organic solvent is used to avoid thermal coloring and thermal deterioration, the organic solvent volatilizes into the air during coating, deteriorating the working environment and easily causing problems such as air pollution.

Next, JP-A-59-176370 discloses that "radical cross-linking to 100 parts by weight of a copolymer having a molecular weight of 100,000 to 600,000 and containing an alkyl ester of acrylic acid or methacrylic acid as a main component is carried out by ultraviolet rays or electron beams. One unsaturated bond that can cause
A pressure-sensitive adhesive composition comprising 1 to 50 parts by weight of an oligomer having a molecular weight of 1,000 to 20,000 having two or more in the molecule and 0 to 10 parts by weight of a photosensitizer and capable of being radically crosslinked by ultraviolet rays or electron beams . "Has been proposed.

However, the oligomer used in the second proposal has a molecular weight larger than the molecular weight range of the compound having "two or more specific ethylenically unsaturated bonds in one molecule" of the present invention. When the viscosity tends to be high, heating at a higher temperature is required to lower the viscosity at the time of coating, and thermal polymerization of the oligomer, thermal deterioration, etc. are easily caused, and the obtained pressure-sensitive adhesive layer is colored. In addition, it tends to be difficult to maintain a balance among various properties, such as heat resistance, pressure-sensitive adhesiveness, adhesive strength, and cohesive strength. There is also a problem that it is difficult to reuse the composition once melted by heating.

The present inventors have conducted research to solve the problems of these conventional active energy ray-curable pressure-sensitive adhesives. As a result, for acrylic (co) polymers having a specific molecular weight,
By containing a specific amount of a compound having a specific molecular weight range having two or more ethylenically unsaturated bonds in one molecule and an antioxidant, the above problems can be solved and an excellent active energy ray-curable hot melt feeling can be obtained. We have found that a pressure-sensitive adhesive composition can be obtained, and filed a patent application (Japanese Unexamined Patent Publication No.
No.-9965). The pressure-sensitive adhesive composition of the present invention was considerably superior to the conventional one, but it may be required to further increase the coating speed for the purpose of higher productivity. In such a case, it is required to further lower the viscosity of the composition. Further, the pressure-sensitive adhesive composition for a hot melt of the above-mentioned invention tends to have insufficient pressure-sensitive adhesiveness as compared with a solvent-type pressure-sensitive adhesive, and furthermore, the adhesive strength, especially a non-polar plastic such as polyethylene. There is also a problem that the adhesive strength to the adhesive is not sufficient.

On the other hand, in order to reduce the viscosity of the pressure-sensitive adhesive at the time of coating, it is conventionally known to use a (meth) acrylic monomer such as n-butyl acrylate as a diluent. , in JP-a-58-108275, "the general formula CH ₂ = CHCOOR ¹ (where R ¹ is an alkyl group having 2 to 14 carbon atoms) different homopolymer or R ¹ acrylic acid ester represented by the A copolymer of acrylic acid esters with a molecular weight of 5,000 to 300,000
100 parts by weight, general formula CH ₂ = CHCOOR ² (where R ² has 2 to 1 carbon atoms)
Characterized in that the composition contains 5 to 40 parts by weight of a monomer represented by formula (4) and 0.01 to 10 parts by weight of an acrylate ester having two or more acryloyl groups in one molecule. The composition. "Has been disclosed.

However, although the pressure-sensitive adhesive composition of the above proposal can lower the viscosity at the time of coating, the acrylic monomer used generally has large volatility, strong odor, and
Due to the high flammability, the working environment during coating is significantly deteriorated, and the problem of a change in the composition over time and a change in viscosity of the pressure-sensitive adhesive composition with the volatilization of the monomer even during storage,
There are many problems such as the danger of fire and the like, and it is hard to say that the adhesive strength to non-polar plastic is sufficient.

The present inventors have conducted further research following the previous invention, and as a result, the active energy ray-curable pressure-sensitive adhesive composition for hot melt of the present invention further includes, for example, ethylene glycol methyl ether acrylate and tetraethylene glycol. 1 such as nonylphenol ether acrylate
The melt viscosity at the time of coating can be reduced by including a specific amount of a specific compound containing one (meth) acryloyl group and a (poly) oxyalkylene chain in the molecule. The excellent various physical properties such as pressure-sensitive adhesiveness and adhesive strength (SUS) of the pressure-sensitive adhesive composition of the present invention can be maintained or further improved.
The present inventors have found that the adhesion to non-polar plastics can be significantly improved, and have completed the present invention.

[Means for solving the problem]

The present invention relates to the following A to D, A. 100 parts by weight of (A) acrylic (co) polymer having a weight average molecular weight of 50,000 to 500,000 by GPC, 1 to 10 parts by weight of one or more compounds selected from the group of compounds having two or more acryloyl groups, methacryloyl groups, allyloxy groups and / or methallyloxy groups, and having a molecular weight of less than 1000, C. 1 to 10 parts by weight of a compound represented by the following general formula, And D. an antioxidant in an amount of 0.1 to 1 part by weight, and an object thereof is to provide an active energy ray-curable pressure-sensitive adhesive for hot melt, which comprises:

 Hereinafter, the present invention will be described in detail.

The active energy ray-curable pressure-sensitive adhesive for hot melt of the present invention is an acrylic (co) polymer, and its GPC
(A) having a polymerization average molecular weight of 50,000 to 500,000 as a main component.

Examples of the acrylic (co) polymer (A) include the following (a) to (c), (a) a general formula CH ₂ CHCHCOOR ⁴ (where R ⁴ is a linear or branched C ₂ -C ₁₈ ) (B) radical polymerization of an acrylate monomer represented by the formula (1), wherein the homopolymer has a glass transition point of −20 ° C. or lower: At least one other than the unsaturated group
(C) copolymerizable with the above (a) and (b),
The use of an acrylic (co) polymer obtained by (co) polymerizing a monomer other than (b) and (b) results in a balance between the adhesive force, cohesive force and pressure-sensitive adhesiveness of the resulting pressure-sensitive adhesive layer. It is preferable from the viewpoint of goodness.

The acrylate monomer of the above (a) is represented by the general formula CH
₂ = CHCOOR ⁴ , the homopolymer has a glass transition point of −20 ° C. or less, and R ⁴ of the acrylate monomer (a) is C _{2 to} C ₁₈ , preferably C ₂ to C ₁₈ . C _{12 represents} a linear or branched alkyl group. Examples of such groups R ^4, an ethyl group, n- propyl group, n- butyl group, i- butyl, n- hexyl, n- octyl group, i- octyl, 2-ethylhexyl, i -Nonyl group and the like. Specific examples thereof include ethyl acrylate, n-propyl acrylate, n-butyl acrylate, i-butyl acrylate, n-hexyl acrylate, n-octyl acrylate, i-octyl acrylate, and 2 -Ethylhexyl acrylate, i-nonyl acrylate, and the like.

The amount of the acrylate monomer (a) used is, for example, 50% in the total 100% by weight of the monomers (a) to (c).
An amount of about 99.5% by weight, preferably about 63-96% by weight is suitable. By appropriately selecting and using the acrylate monomer (a) in the above-mentioned usage amount range, adhesive strength,
A good balance between pressure sensitive adhesion and cohesion can be achieved.

The monomer having at least one functional group in addition to the radically polymerizable unsaturated group (b) may be a functional group such as a carboxyl group, an amide group or a substituted amide group, or an amino group. Alternatively, a monomer having a substituted amino group, a hydroxyl group, a mercapto group, or the like can be given. In the present invention, one or more monomers can be appropriately selected from these and used. . Specific examples of these monomers include, for example, acrylic acid, methacrylic acid, itaconic acid, maleic acid, maleic anhydride, fumaric acid, crotonic acid, citraconic acid (preferably acrylic acid, methacrylic acid, itaconic acid) and the like. Carboxyl group-containing monomers; for example, acrylamide,
Methacrylamide, N, N-dimethylacrylamide, N
Amide group- or substituted amide group-containing monomers such as methylacrylamide (preferably acrylamide, methacrylamide); for example, aminoethyl acrylate, N, N-dimethylaminoethyl acrylate, N, N-diethylaminoethyl acrylate, N, Amino- or substituted amino-group-containing monomers such as N-dimethylaminoethyl methacrylate, N, N-diethylaminoethyl methacrylate, (preferably, N, N-dimethylaminoethyl methacrylate and N, N-diethylaminoethyl methacrylate); , 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, 2-hydroxyethyl methacrylate, allyl alcohol, methallyl alcohol (preferably 2-hydroxyethyl acrylate, 2-hydroxypropyl Acrylate, 2-
Hydroxyl-containing monomers such as hydroxyethyl methacrylate and 2-hydroxypropyl methacrylate); mercapto-containing monomers such as vinyl mercaptan and allyl mercaptan; and the like. Among these monomers (b), a carboxy group-containing monomer,
It is particularly preferable to use at least one or more monomers selected from the group consisting of an amide group-containing monomer and a substituted amino group-containing monomer.

The amount of the monomer (b) to be used depends on the amount of the monomer (a) to
For example, 0.5 to 15% by weight, preferably about 1 to 10% by weight of the total 100% by weight of (c) can be exemplified. When the amount of the monomer (b) used is equal to or less than the upper limit, the pressure-sensitive adhesive property of the obtained active energy ray-curable pressure-sensitive adhesive for hot melt does not become too low. But especially 0.
It is preferable that the content be 5% by weight or more because a good balance between the adhesive force and the cohesive force can be achieved.

Further, comonomer (c) which is a monomer copolymerizable with the monomers (a) and (b) and which is other than the monomer (a) and (b), For example, acrylate monomers other than the above (a) such as methyl acrylate, t-butyl acrylate, cyclohexyl acrylate, and stearyl acrylate; for example, methyl methacrylate, ethyl methacrylate, n-butyl methacrylate, i-butyl methacrylate, and t -Butyl methacrylate, n-hexyl methacrylate, cyclohexyl methacrylate, n-octyl methacrylate, i-octyl methacrylate, 2-ethylhexyl methacrylate, i-nonyl methacrylate, n-dodecyl methacrylate, i-dodecyl methacrylate, stearyl methacrylate, etc. Lylic acid ester monomers; for example, saturated fatty acid vinyl ester monomers such as vinyl formate, vinyl acetate, vinyl propionate, and vinyl versatate; for example, dibutyl malate, dibutyl fumarate, dibutyl itaconate, dioctyl malate; Α, β such as dioctyl fumarate and dioctyl itaconate
A C _{1 to} C ₁₈ linear or branched alkyl ester of an unsaturated dicarboxylic acid; for example, an aromatic vinyl monomer such as styrene, α-methylstyrene, vinyltoluene, and ethylvinylbenzene; for example, acrylonitrile, methacryloyl Vinyl cyanide monomer such as nitrile; and the like.

The amount of the comonomer (c) used is from the above-mentioned monomers (a) to
In general, an amount of about 0 to 49.5% by weight, preferably about 3 to 36% by weight, of the total 100% by weight of (c) is suitable. Since the amount can vary depending on the species, the amount to be used cannot be uniquely determined, but it is useful for adjusting the balance between the adhesive force and the pressure-sensitive adhesiveness and the balance between these and the cohesive force as desired. The above range can be appropriately selected so as to meet such purposes. When the amount of the comonomer (c) is equal to or less than the upper limit of the above range, the pressure-sensitive adhesiveness does not become too low, and an appropriate balance between the adhesive force and the pressure-sensitive adhesiveness is maintained. Therefore, when the comonomer (c) is used, it is preferable to select and use an appropriate amount within the above range.

The glass transition point (hereinafter, sometimes abbreviated as Tg) of an acrylic (co) polymer which is a main component of the active energy ray-curable pressure-sensitive adhesive for hot melt of the present invention is preferably −20 ° C. or lower. -30 ° C or lower. Temperatures below the upper limit are preferred because they have excellent pressure sensitive adhesion.

Further, the weight average molecular weight of the acrylic (co) polymer according to the GPC method (hereinafter may be abbreviated as Mw).
Is from 500,000 to 500,000, preferably from 100,000 to 400,000. Below the lower limit, the adhesive strength and cohesive strength of the obtained pressure-sensitive adhesive layer may be insufficient, while above the upper limit, a higher melting temperature may be required to obtain a suitable coating viscosity. Since it is necessary, thermal degradation of the acrylic (co) polymer and thermal polymerization of a compound having two or more acryloyl, methacryloyl, allyloxy and / or metallyloxy groups in one molecule described later, etc. This is not preferable because the above may occur.

In the present invention, the glass transition point (Tg) of the acrylic (co) polymer is a value measured and determined as follows.

Glass transition point: Approximately 10 mg of a sample of a 50% by weight organic solvent solution of an acrylic (co) polymer was weighed into a cylindrical cell made of aluminum foil having a thickness of about 0.05 mm and having an inner diameter of about 5 mm and a depth of about 5 mm. The sample is taken and dried at 100 ° C. for 2 hours to obtain a measurement sample. SSC-5000 differential scanning calorimeter manufactured by Seiko Electronic Industry Co., Ltd. (Differential
Using a Scanning Calormeter, the rate of temperature rise from -150 ° C to 10
Measure and determine in ° C / min.

The method for polymerizing the acrylic (co) polymer of the present invention is not particularly limited, and known methods such as solution polymerization and emulsion polymerization can be employed. In producing an energy ray-curable pressure-sensitive adhesive for hot melt, it is preferable to employ solution polymerization in which the processing steps are relatively simple and can be performed in a short time.

In the solution polymerization, generally, a predetermined organic solvent, a monomer, a polymerization initiator and a chain transfer agent used as needed are charged into a polymerization system, and a heating reaction is performed for several hours while stirring in a nitrogen stream or at the reflux temperature of the organic solvent. In this case, an organic solvent, a monomer, a polymerization initiator and / or a chain transfer agent may be sequentially added.

As the organic solvent, for example, benzene, toluene, xylene, aromatic hydrocarbons such as aromatic naphtha; n-
Aliphatic or alicyclic hydrocarbons such as hexane, n-heptane, n-octane, i-octane, n-decane, dipentene, petroleum spirit, petroleum naphtha, turpentine oil; ethyl acetate, n-butyl acetate; n-
Esters such as amyl acetate, 3-methoxybutyl acetate, methyl benzoate, cellosolve acetate, butyl cellosolve acetate; ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone, isophorone, cyclohexanone, methyl cyclohexanone; Ethers such as alcohols such as methyl alcohol, methyl alcohol, n-propyl alcohol, i-propyl alcohol, n-butyl alcohol, i-butyl alcohol, s-butyl alcohol and t-butyl alcohol; These organic solvents can be used alone or in combination of two or more.

Since the active energy ray-curable pressure-sensitive adhesive for hot melt of the present invention needs to be substantially solvent-free, among these organic solvents, the obtained (co) polymer solution is used to convert the organic solvent. It is preferable to use an organic solvent having a boiling point of 50 to 150 ° C., particularly preferably 60 to 100 ° C., which is easy to volatilize and isolate a (co) polymer, especially n-hexane, ethyl acetate, acetone It is particularly preferable to use an organic solvent such as methyl ethyl ketone, methyl alcohol and n-propyl alcohol.

Examples of the polymerization initiator include benzoyl peroxide, lauroyl peroxide, caproyl peroxide, di-i-propylperoxydicarbonate, di-2-ethylhexylperoxydicarbonate, t-butylperoxyvivalate, and the like. Organic peroxides of, for example, 2,2'-azobis-i-butyronitrile,
2,2'-azobis-2,4-dimethylvaleronitrile, 2,
An azo compound such as 2'-azobis-4-methoxy-2,4-dimethylvaleronitrile; and the like can be used alone or in combination. The polymerization initiator is generally used in an amount of about 0.01 to 0.3 parts by weight, more preferably about 0.01 to 0.15 parts by weight, based on 100 parts by weight of the total amount of the monomers.

Examples of the chain transfer agent include, for example, cyanoacetic acid; alkyl group C _{1 to} C ₈ cyanoacetate alkyl ester group; bromoacetic acid; alkyl group C _{1 to} C ₈ bromoacetic acid esters; anthracene, phenanthrene, fluorene, 9
Aromatic compounds such as -phenylfluorene; aromatic nitro compounds such as p-nitroaniline, ntrobenzene, dinitrobenzene, p-nitrobenzoic acid, p-nitrophenol, p-nitrotoluene, benzoquinone, 2,3,5, 6
Benzoquinone derivatives such as -tetramethyl-p-benzoquinone; borane derivatives such as tributylborane; carbon tetrabromide, carbon tetrachloride, 1,1,2,2-tetrabromoethane, tribromoethylene, trichloroethylene, bromotrichloromethane , tribromomethane, 3-chloro-1-halogenated hydrocarbons such as propene, chloral, aldehydes such as furaldehyde, alkyl mercaptans C ₁ -C _18; thiophenol, aromatic Merutaputan such as toluene mercaptan; Mercaptoacetic acid; C _{1 of} mercaptoacetic acid
-C ₁₀ alkyl esters; C ₁ hydroxamate Le alkyl mercaptans -C ₁₂ Binen, Tempel such as Tapinoren; and the like.

When the above-mentioned chain transfer agent is used, the amount thereof is preferably about 0.005 to 3.0 parts by weight per 100 parts by weight of the total of monomers.

The polymerization temperature is generally in the range of about 30 to 180 ° C, preferably about 60 to 150 ° C.

The (co) polymer solution suitably used in the present invention thus obtained usually has a weight of the acrylic (co) heavy body of from 20 to 20.
To obtain the hot-melt pressure-sensitive adhesive of the present invention, the organic solvent is removed from the (co) polymer solution by a known method such as distillation to remove the acrylic (co) The polymer is isolated.

The active energy ray-curable pressure-sensitive adhesive for hot melt of the present invention, together with the acrylic (co) polymer (A), contains two acryloyl groups, methacryloyl groups, allyloxy groups and / or metalloxy groups in one molecule. Compounds having a molecular weight of less than 1000 (hereinafter, referred to as
(May be abbreviated as a polyunsaturated compound)) or one or more compounds (B) selected from the group consisting of:

When a polyunsaturated compound (B) having a molecular weight of 1,000 or more is used, the melt viscosity of the obtained hot-melt pressure-sensitive adhesive becomes high, so that a higher melting temperature is required to obtain a suitable coating viscosity. However, in this case, thermal deterioration of the acrylic (co) polymer and thermal polymerization of the polyunsaturated compound or the like may occur, which is not preferable.

Such polyunsaturated compounds include, for example, ethylene glycol diglycidyl ether diacrylate,
Diethylene glycol diglycidyl ether dimethacrylate, triethylene glycol diglycidyl ether dimethacrylate, propylene glycol diglycidyl ether diacrylate, sorivitol tetraglycidyl ether tetramethacrylate, glycerol triglycidyl ether triacrylate, bisphenol A
Poly (meth) acrylates of polyepoxy compounds such as diglycidyl ether diacrylate; for example, ethylene glycol dimethacrylate, diethylene glycol diacrylate, tetraethylene glycol diacrylate, tripropylene glycol diacrylate, 1,4
-Butanediol diacrylate, neopentyl glycol dimethacrylate, 1,6-hexanediol diacrylate, neopentyl glycol diacrylate hydroxybivalate, trimethylolethane trimethacrylate, trimethylolpropane triacrylate, ethoxylated trimethylolpropane triacrylate Poly (metal) acrylates of polyols such as pentaerythritol triacrylate, pentaerythritol tetraacrylate and dipentaerythritol hexaacrylate; (meth) allyl (meth) acrylates such as allyl acrylate and allyl methacrylate;
For example, (meth) allyl esters of radically polymerizable dicarboxylic acids such as diallyl maleate, diallyl fumarate and diallyl itaconate; for example, other polycarboxylic acids such as diallyl phthalate, triallyl cyanurate and triallyl isocyanurate (Meth) allyl ester; and the like.

Among these polyunsaturated compounds (B), the use of polyol poly (meth) acrylate is preferred from the viewpoints of easy availability and good balance of various physical properties of the obtained pressure-sensitive adhesive. These can be used alone or in combination of two or more.
It is preferable to use a mixture of two or more of these polyunsaturated compounds for reasons such as a good balance between adhesion and cohesion.

The amount of the polyunsaturated compound (B) used is 1 to 10 parts by weight, preferably 2 to 8 parts by weight, based on 100 parts by weight of the acrylic (co) polymer (A). If the pressure-sensitive adhesive layer is used in excess of the upper limit, the pressure-sensitive adhesive property of the resulting pressure-sensitive adhesive layer may be reduced. Is insufficient, and the cohesive strength and adhesive strength of the pressure-sensitive adhesive layer may be insufficient, which is not preferable.

The active energy ray-curable pressure-sensitive adhesive for hot melt of the present invention can be used together with the acrylic (co) polymer (A) and the polyunsaturated compound (B) together with the following general formula: CH ₂ = CR ¹ COO _{^{- (R 2 O) n -R}} 3 ... compound represented by (C) is one comprising (hereinafter, sometimes abbreviated as oxyalkylene monomer). Here, R ¹ is H or CH ₃ , R ² is a C _{2 to} C ₆ linear or branched alkylene group, n is an integer of 1 to 30, R ³ is C _{1 to} C ₁₂
Or a C ₆ -C ₁₈ phenyl or alkylphenyl group.

Specific examples of such a compound (C) include, for example,
Ethylene glycol methyl ether acrylate, ethylene glycol n-butyl ether acrylate, ethylene glycol phenol ether acrylate, ethylene glycol nonyl phenol ether acrylate, diethylene glycol methyl ether methacrylate, diethylene glycol 2-ethylhexyl ether acrylate, triethylene glycol methyl ether acrylate, tetraethylene glycol methyl ether methacrylate , Tetraethylene glycol phenol ether acrylate, tetraethylene glycol nonyl phenol ether acrylate, polyethylene glycol (n = about 9) methyl ether methacrylate,
Dipropylene glycol methyl ether acrylate,
Examples include polypropylene glycol (n = about 2.5) nonylphenol ether acrylate.

The amount of the compound (C) used is the same as that of the acrylic (co)
The amount is 1 to 10 parts by weight, preferably 2 to 8 parts by weight, based on 100 parts by weight of the polymer (A). If the amount is less than the lower limit, the effect of lowering the viscosity of the obtained adhesive at the time of coating is insufficient, which is not preferable.If the amount exceeds the upper limit, the amount is too large. In addition, the adhesive strength may decrease, which is not preferable.

Both the components (B) and (C) are used as diluents for the acrylic (co) polymer (A) before irradiation with active energy rays so as to maintain the viscosity at the time of coating at a moderately low level. It is preferable to use a material which is polymerized by irradiation with active energy rays and / or undergoes a cross-linking reaction with the acrylic (co) polymer (A) to form a solid resin. Therefore, as the components (B) and (C), those having a melting point of room temperature (about 20 ° C.) or less and a boiling point of 160 ° C. or more, preferably 200 ° C. or more are preferable.

The active energy ray-curable pressure-sensitive adhesive for hot melt of the present invention is the above-mentioned acrylic (co) polymer (A), polyunsaturated compound (B), oxyalkylene-based monomer (C)
At the same time, the antioxidant (D) is added to the (co) polymer (A) 10
It is contained in an amount of 0.1 to 1 part by weight based on 0 part by weight. When the amount of the antioxidant (D) exceeds the upper limit,
The curing reaction by active energy ray irradiation hardly proceeds sufficiently, and the cohesive strength and adhesive strength of the obtained pressure-sensitive adhesive layer may be insufficient, which is not preferable. On the other hand, if it is less than the lower limit, the addition of the component (D) is not preferable. The effect is difficult to appear, and the acrylic (co) polymer may be thermally degraded at the time of heat application, or the polyunsaturated compound or the like may be thermally polymerized, so that an excellent pressure-sensitive adhesive layer may not be obtained. At the same time, it may not be possible to reuse the heated pressure-sensitive adhesive for hot melt, which is not preferable.

As the above antioxidant, generally, phenolic,
There are aromatic amines, sulfides, phosphites and the like. Of these, for example, 2,6-di-t-butyl-
4-methylphenol, n-octadecyl-3-
(3 ', 5'-di-t-butyl-4'-hydroxyphenyl) propionate, pentaerythritol-tetrakis [3- (3', 5-di-t-butyl-4'-hydroxyphenyl) propionate], 2 Phenolic antioxidants such as 2,2'-methylenepis (6-t-butyl-4-methylphenol) monoacrylate are preferable because of their excellent heat stability, oxidation stability, heat discoloration resistance, body transpiration and the like. 2,2'-Methylenebis (6-t-butyl-4-methylphenol) monoacrylate is most preferred from the viewpoint of the less coloring of the pressure-sensitive adhesive layer from which the resulting pressure-sensitive adhesive layer is obtained.

The active energy ray-curable pressure-sensitive adhesive for hot melt of the present invention, when using an ultraviolet ray or the like as an active energy ray as described later, is formed of the acrylic (co) polymer (A) and the polyunsaturated compound ( B), an oxyalkylene-based monomer (C) and an antioxidant (D (a photopolymerization initiator may be used in combination with the antioxidant (D)).

Examples of the photopolymerization initiator include, for example, diacetyl, benzene, benzophenone, benzoin, ω-bromoacetophenone, chloroacetone, benzoquinone, anthraquinone, 2-ethylanthraquinone, benzoyl isopropyl ether, and benzoin ethyl ether. Can be 0.1 to 15 parts by weight based on 100 parts by weight of the total of (A) to (C).

In addition, the pressure-sensitive adhesive of the present invention has a boiling point of water and the organic solvent used in the solution polymerization of the acrylic (co) polymer, as long as the excellent effects of the present invention are not impaired. It may contain volatile solvents of 250 ° C. or less under normal conditions, but the content of these solvents is acrylic (co)
10 parts by weight or less, preferably 5 parts by weight or less, particularly preferably 1 part by weight or less based on 100 parts by weight in total of the polymer (A), the polyunsaturated compound (B) and the oxyalkylene monomer (C). It is good.

The pressure-sensitive adhesive of the present invention may further comprise, if necessary, for example, coumarone-indene resin, terpene-phenol resin, pt-butylphenol-acetylene resin, phenol-formaldehyde resin, tempel resin, xylene-formaldehyde resin, petroleum Tackifying resin such as a series hydrocarbon resin, a hydrogenated hydrocarbon resin, a rosin derivative, a turpentine resin; for example, ethylene-vinyl acetate copolymer resin, ethylene-acrylic copolymer resin, ethylene-vinyl acetate- Other modifying resins such as an acrylic copolymer resin; and the like can be added. The addition amount of these resins is, based on 100 parts by weight of the total of the components (A) to (C), a tackifying resin, for example, 0 to 60 parts by weight, particularly 0 to 40 parts by weight; Resin, for example, 0 to 50 parts by weight, particularly 0 to 20 parts by weight;

In addition to these, the pressure-sensitive adhesive of the present invention may be used, if necessary, as necessary, for example, a phthalate ester such as dioctyl phthalate, a phosphate ester such as tricresyl phosphate, a plasticizer such as polybute or process oil; For example, organic or inorganic colorants such as titanium oxide, carbon black, and phthalocyanine blue; for example, clay, talc,
Known additives such as inorganic fillers such as calcium carbonate, silica, aluminum hydroxide, and glass powder; a photopolymerization initiation aid, an ultraviolet absorber, and a preservative;

As described above, the pressure-sensitive adhesive of the present invention is preferably added to an acrylic (co) polymer solution obtained by solution polymerization in an organic solvent having a boiling point of 60 to 100 ° C such as ethyl acetate, for example, trimethylolpropane. Polyunsaturated compounds (B) such as triacrylate and ethoxylated trimethylolpropane triacrylate, for example, polypropylene glycol (n ≒ 2.5) nonylphenol ether acrylate [trade name: ARONIX M-117, manufactured by Toa Gosei Chemical Industry Co., Ltd.] Oxyalkylene-based monomers (C) such as 2,2'-methylenebis (6-t-butyl-4-methylphenol) monoacrylate [trade name: Sumilizer GM, manufactured by Sumitomo Chemical Co., Ltd.] Antioxidant (D) and, if necessary, for example, a photopolymerization initiator such as benzoin ethyl ether After sufficiently stirring and mixing, the organic solvent used during the solution polymerization is distilled off by heating, and the organic solvent is further removed using a means such as drying under reduced pressure.If necessary, a tackifying resin may be used. Denaturing resin,
It can be produced by adding and mixing a plasticizer and a pigment.

The active energy ray-curable pressure-sensitive adhesive for hot melt of the present invention is generally hot-melted according to a known method, applied to various substrates at an appropriate thickness, and then formed into a layer of the composition. By irradiating the active energy ray to such an extent that the pressure-sensitive adhesive property is not lost, the composition can be cured to form a pressure-sensitive adhesive layer on the substrate. Examples of the melting temperature include a temperature of about 100 to 180 ° C.

The above active energy rays are ultraviolet rays or electron beams,
It refers to ionizing radiation such as α-rays, β-rays, γ-rays, or X-rays. From the viewpoints of problems with equipment, ease of handling, and the use of pressure-sensitive adhesives with better storage stability, etc. The use of electron beams is preferred.

The "to the extent that the pressure-sensitive adhesive is not lost" means, as described later, that the value of the pressure-sensitive adhesiveness is 100 g / value according to the method of JIS Z-0237.
It means that it is 25mm or more.

For example, when the active energy ray is ultraviolet light, the irradiation dose of the active energy ray can be adjusted by adjusting the intensity of the lamp, the distance to the surface to be irradiated, and the irradiation time. 10 using a luminometer
10001000 mJ / cm ² , preferably 50 to 500 mJ / cm ² .

In the case of an electron beam, for example, the irradiation dose can be adjusted by adjusting the voltage, current, and irradiation time, and the dose is measured using a CTA dosimeter on the irradiation surface, and is 0.5 to 10 Mrad, preferably 2 to 8 Mrad. It is better to

〔Example〕

Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples.

The method for measuring the viscosity at the time of heating and the method for evaluating the thermal stability of the adhesive of the present invention, the method for preparing a pressure-sensitive adhesive sheet for the physical property test of the pressure-sensitive adhesive layer, and the methods for measuring the secondary adhesiveness and adhesive force are as follows. It is as follows.

(1) Measurement of viscosity during heating Using a Contrabass viscometer Rheomat 30 (trade name), cone plate PK1, measurement temperature 150 ° C, shear rate 50se
Measure under the condition of c- ¹ . The hot viscosity of the adhesive of the present invention is preferably 10,000 cps or less.

(2) Thermal stability of the adhesive The pressure-sensitive adhesive for energy ray-curable hot melt is placed in a glass bottle, sealed, and left in a thermostat at 150 ° C. to measure the time until the fluidity disappears. The thermal stability is preferably at least one day, particularly preferably at least three days.

(3) Method of preparing pressure-sensitive adhesive sheet for test A 50 µm polyethylene terephthalate film coated with an electron beam-curable hot melt pressure-sensitive adhesive melted at 150 ° C to a thickness of about 25 µm Then, the surface of the obtained adhesive layer was irradiated with an electron beam of 4 Mrad and cured to obtain a test pressure-sensitive adhesive sheet.

(4) Measurement of pressure-sensitive adhesiveness S brushed with 3280 water-resistant abrasive paper specified in JIS R-6253
Using a test pressure-sensitive adhesive sheet prepared in (3) on a US 304 stainless steel plate, press-fit according to the method of JIS Z-0237.
After 0 minute, the peel strength (g / 25 mm) is measured under the conditions of 20 ° C., 65% RH, and a peel speed of 300 mm / min. The value of the pressure-sensitive adhesiveness is preferably 600 g / 25 mm or more, and 1000 g / 25 m
It is particularly preferred that it is at least m.

(5) Measurement of adhesive strength Polished with # 280 water-resistant abrasive paper specified in JIS R-6253
SUS 304 stainless steel plate and polyethylene plate (JIS K
Γ ₀ = 43 dyn / cm) using the pressure-sensitive adhesive sheet for test prepared in (3) according to the method of JIS Z-0237 according to the method specified in −6768, and after 24 hours, 20 ° C., 65% RH. , Peeling speed
The peel strength (g / 25 mm) is measured under the condition of 300 mm / min. The adhesive strength is preferably 100 g / 25 mm or more, particularly preferably 1400 g / 25 mm or more.

Reference Example 1 In a separable flask equipped with a reflux condenser, a thermometer, a stirrer, and a sequential dropping device, 80 parts by weight of ethyl acetate (EAc) and azobisisobutyronitrile as an organic solvent for initial addition and a polymerization initiator. (AIBN) 0.0125 parts by weight, and then add 25 parts by weight of a monomer mixture consisting of 94 parts by weight of butyl acrylate (BA) and 6 parts by weight of acrylic acid (AA), and heat the mixture. The polymerization was carried out for 40 minutes while adjusting the temperature.

Next, while maintaining the internal temperature at 80 to 85 ° C., a mixture for sequential addition consisting of 75 parts by weight of the remaining amount of the monomer mixture, 20 parts by weight of EAc and 0.125 parts by weight of AIBN was successively dropped over about 90 minutes, and further 90 parts by weight. While maintaining the internal temperature at 80 to 85 ° C. for one minute, an acrylic copolymer solution having a solid content of about 50% by weight was obtained. The w of this copolymer is 17
The Tg was -42 ° C.

Reference Examples 2 to 5 Using the same apparatus as in Reference Example 1 and using the monomer composition, the initial addition mixture and the sequential addition mixture shown in Table 1, polymerization was carried out in the same manner as in Reference Example 1 to obtain an acrylic resin. A copolymer solution was obtained. Table 1 shows w and Tg of this copolymer.

Example 1 To 100 parts by weight of the acrylic copolymer solution obtained in Reference Example 1, Sumilizer GM [trade name: 2,2'-methylenebis (6-t-manufactured by Sumitomo Chemical Co., Ltd.) was used as an antioxidant. Butyl-4-methylphenol) monoacrylate (MBPM
A)], add 0.25 parts by weight, mix and concentrate by vacuum drying to a solid content of 99% by weight, and then trimethylolpropane triacrylate (TMPTA) as a polyunsaturated compound.
0.5 parts by weight and 1.5 parts by weight of Photomer 4149-SN [trade name; manufactured by San Nopco Co., Ltd .: ethoxylated trimethylolpropane triacrylate (TMPTEA)], and ARONIC M-117 [trade name; TOA as an oxyalkylene monomer] Synthetic Chemical Industry Co., Ltd .: Polypropylene glycol (n ≒
2.5) Nonylphenol ether acrylate] was mixed with 2.5 parts by weight to obtain an electron beam-curable pressure-sensitive adhesive for hot melt. Table 2 shows the measurement results of various physical properties of the obtained adhesive.

Example 2 and Comparative Examples 1 and 2 An electron beam-curable pressure-sensitive adhesive for hot melt was obtained in the same manner as in Example 1, except that the amount of TMPTA and / or TMPTEA was changed. Table 2 shows the composition of the obtained adhesive and the measurement results of various physical properties.

Comparative Example 3 An electron beam-curable pressure-sensitive adhesive for hot melt was obtained in the same manner as in Example 1, except that ARONIC M-117 (trade name) was not used. Table 2 shows the composition of the obtained adhesive and the measurement results of various physical properties.

Examples 3 to 6 and Comparative Example 4 In Example 1, Blenmer PEM-100 [trade name; Nippon Oil & Fats Co., Ltd.] was used instead of ARONIC M-117 (trade name).
Diethylene glycol methyl ether methacrylate] 2-MTA [trade name; manufactured by Osaka Organic Chemical Industries, Ltd .: ethylene glycol methyl ether acrylate], light acrylate BO-A [trade name: manufactured by Kyoeisha Yushi Kagaku Kogyo Co., Ltd .: ethylene Glycol n-butyl ether acrylate], Aronix M-113 (trade name; manufactured by Toagosei Chemical Industry Co., Ltd .: tetraethylene glycol nonyl phenol ether acrylate) or 2-ethylhexyl acrylate (2EHA) in the same manner except for using electron beam curing. A pressure-sensitive adhesive for mold hot melt was obtained. Table 2 shows the composition of the obtained adhesive and the measurement results of various physical properties.

Comparative Examples 5 and 6 In the same manner as in Example 1, except that the acrylic copolymer solution of Reference Example 2 or 3 was used instead of the acrylic copolymer dense liquid of Reference Example 1, for an electron beam-curable hot melt. A pressure-sensitive adhesive was obtained. Table 2 shows the composition of the obtained adhesive and the measurement results of various physical properties.

Comparative Example 7 An electron beam-curable pressure-sensitive adhesive for hot melt was obtained in the same manner as in Example 1 except that no antioxidant was used. Table 2 shows the composition of the obtained adhesive and the measurement results of various physical properties.

Examples 7 and 8 The same procedure as in Example 1 was carried out except that the acrylic copolymer solution of Reference Example 4 or 5 was used instead of the acrylic copolymer solution of Reference Example 1. A pressure-sensitive adhesive was obtained. Table 2 shows the composition of the obtained adhesive and the measurement results of various physical properties.

Continuation of the front page (56) References JP-A-59-157164 (JP, A) JP-A-2-276879 (JP, A) JP-A-2-248482 (JP, A) (58) Fields investigated (Int) .Cl. ⁶ , DB name) C09J 4/06 C09J 133/04-133/16 C09J 171/00

Claims (1)

(57) [Claims] 1. The following A to D, A. 100 parts by weight of an acrylic (co) polymer having a weight average molecular weight by GPC of 50,000 to 500,000, and B. 1 molecule 1 to 10 parts by weight of one or more compounds selected from the group of compounds having two or more acryloyl groups, methacryloyl groups, allyloxy groups and / or methacryloxy groups and having a molecular weight of less than 1000 C. 1 to 10 parts by weight of a compound represented by the following general formula, And D. 0.1 to 1 part by weight of an antioxidant. An active energy ray-curable pressure-sensitive adhesive for hot melt, characterized by comprising: