JP2789235B2 - Active energy ray-curable hot melt pressure sensitive adhesive composition - Google Patents

Description

The present invention relates to an active energy ray-curable hot-melt pressure-sensitive adhesive composition, and more particularly to an acrylic (co) polymer having a specific molecular weight. The amount of one or more compounds selected from the group of compounds having a specific molecular weight range having two or more specific ethylenically unsaturated bonds in one molecule, the specific amount of a specific diene compound, and the specification of an antioxidant The present invention relates to an active energy ray-curable hot-melt pressure-sensitive adhesive composition, characterized in that the composition contains an amount thereof.

[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 also 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 between 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 found that a pressure-sensitive adhesive composition could be obtained, and filed a patent application (Japanese Patent Application No. Hei.
No.-9965). The pressure-sensitive adhesive composition of the present invention was considerably superior to the conventional one, but a higher coating speed may be required 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 hot melt of the above-mentioned invention tends to have insufficient pressure-sensitive adhesiveness as compared with a solvent-type pressure-sensitive adhesive, and further has an adhesive force to a nonpolar plastic such as polyethylene. There was also a problem that it was not enough.

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. 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 its high flammability, it significantly deteriorates the working environment at the time of coating, and also causes a problem of a change over time in the composition and viscosity of the pressure-sensitive adhesive composition accompanying the volatilization of the monomer during storage,
There are many problems, such as the danger of fire, etc., and the adhesion to non-polar plastics is not sufficiently satisfactory.

As a result of further research by the present inventors following the previous invention, the active energy ray-curable pressure-sensitive adhesive composition for hot melt of the present invention further contains a specific diene such as 1,9-decadiene. The melt viscosity at the time of coating can be reduced by including a specific amount of the system compound, from the beginning, such as the pressure-sensitive adhesiveness and adhesive strength of the pressure-sensitive adhesive composition of the previous invention had It has been found that excellent physical properties can be maintained or further improved, and that the adhesive strength to non-polar plastics can be significantly improved,
The present invention has been completed.

[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, It is another object of the present invention to provide an active energy ray-curable hot-melt pressure-sensitive adhesive composition comprising: D. 0.1 to 1 part by weight of an antioxidant.

 Hereinafter, the present invention will be described in detail.

The active energy ray-curable hot melt pressure-sensitive adhesive composition of the present invention is an acrylic (co) polymer having a polymerization average molecular weight of 50,000 to 500,000 by GPC (A) polymer (A). Is contained 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 following 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.

Examples of the monomer having at least one functional group in addition to the radically polymerizable unsaturated group (b) include a functional group such as a carboxyl group, an amide group or a substituted amide group, and 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 monomer; for example, acrylamide, methacrylamide, N, N-dimethylacrylamide, N-
Methyl acrylamide (preferably, acrylamide,
An amide group or a substituted amide group-containing monomer such as methacrylamide); for example, aminoethyl acrylate, N,
N-dimethylaminoethyl acrylate, N, N-diethylaminoethyl acrylate, N, N-dimethylaminoethyl methacrylate, N, N-diethylaminoethyl methacrylate, (preferably, N, N-dimethylaminoethyl methacrylate, N, N-diethylamino An amino group- or substituted amino group-containing monomer such as ethyl methacrylate;
Hydroxyl-containing monomers such as hydroxypropyl acrylate, 2-hydroxyethyl methacrylate, allyl alcohol, and methallyl alcohol (preferably, 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, 2-hydroxyethyl methacrylate, and 2-hydroxypropyl methacrylate) A mercapto group-containing monomer such as vinyl mercaptan and allyl mercaptan; and the like. Among these monomers (b), it is preferable to use at least one or more monomers selected from the group consisting of a carboxy group-containing monomer, an amide group-containing monomer and a substituted amino group-containing monomer. Particularly preferred.

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 adhesiveness of the obtained active energy ray-curable hot melt pressure-sensitive adhesive composition does not become too low. It is preferable that the amount is 0.5% by weight or more, because a good balance between the adhesive force and the cohesive force can be achieved.

Further, as a monomer copolymerizable with the monomers (a) and (b), and a comonomer (C) other than the monomers (a) and (b), For example, acrylic acid ester monomers other than the above (a) such as methyl acrylate, t-butyl acrylate, cyclohexyl acrylate, stearyl acrylate, etc .; for example, methyl methacrylate, ethyl methacrylate, n-butyl methacrylate, i-butyl methacrylate, t-butyl methacrylate Metals such as 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 and stearyl methacrylate Acrylic acid ester monomer; for example, vinyl formate, vinyl acetate, vinyl propionate and vinyl versatate acid saturated fatty acid vinyl ester monomers; e.g., dibutyl maleate, dibutyl fumarate,
Dibutyl itaconate, dioctyl malate, dioctyl fumarate, straight-chain or branched alkyl esters of C ₁ -C ₁₈ of alpha, beta-unsaturated dicarboxylic acids such as dioctyl itaconate; for example, styrene, alpha-methyl styrene,
Aromatic vinyl monomers such as vinyl toluene and ethyl vinyl benzene; vinyl cyanide monomers such as acrylonitrile and methacrylonitrile;

The amount of the comonomer (c) used is from the above-mentioned monomers (a) to
In general, the amount is preferably about 0 to 49.5% by weight, preferably about 3 to 36% by weight based on the total 100% by weight of (c). Since the use of the comonomer (c) can vary depending on the type of the comonomer, the amount of the comonomer cannot be uniquely determined. It is useful to adjust the balance and the like as desired, so that the above range can be appropriately selected so as to meet such purpose. 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 acryl-based (co) polymer which is a main component of the active energy ray-curable hot melt pressure-sensitive adhesive composition of the present invention is preferably −20 ° C. Or less, more preferably -30 ° C or less. Temperatures below the upper limit are preferred because they have excellent pressure sensitive adhesive properties.

The weight average molecular weight of the acrylic (co) polymer according to the GPC method (hereinafter, may be abbreviated as w).
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 active energy ray-curable hot-melt pressure-sensitive adhesive composition from a polymer mixture, it is preferable to employ solution polymerization in which a processing step is 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, and terepan oil; ethyl acetate, n-butyl acetate; n-
Esters such as amyl acetate, 3-methoxybutyl acetate, methyl benzoate, cellosolve acetate, butyl cellosoble acetate; ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone, isophorone, cyclohexanone, methyl cyclohexanone; methyl cellosolve, ethyl cellosolve; Ethers such as butyl cellosolve; alcohols such as methyl alcohol, ethyl alcohol, n-propyl alcohol, i-propyl alcohol, n-butyl alcohol, i-butyl alcohol, s-butyl alcohol and t-butyl alcohol; be able to. These organic solvents can be used alone or in combination of two or more.

The active energy ray-curable hot-melt pressure-sensitive adhesive composition of the present invention needs to be substantially solvent-free. Therefore, among these organic solvents, the obtained (co) polymer solution is used to prepare the organic solvent. It is preferable to use an organic solvent having a boiling point of from 50 to 150 ° C., particularly from 60 to 100 ° C., which is easy to evaporate the solvent and isolate the (co) polymer, among which n-hexane, ethyl acetate, It is particularly preferable to use an organic solvent such as acetone, 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.

Further, as the chain transfer agent, for example, cyanoacetic acid; alkyl cyanoacetate esters alkyl group C ₁ -C _8; bromoacetic acid esters alkyl group C ₁ -C _8;; bromoacetate Asetorasen, phenanthrene, fluorene, 9
Aromatic compounds such as -phenylfluorene; p-nitriloaniline, nitrobenzene, dinitrobenzene, p-
Aromatic nitro compounds such as nitrobenzoic acid, p-nitrophenol and p-nitrotoluene; benzoquinone, 2,3,
Benzoquinone derivatives such as 5,6-tetramethyl-p-benzoquinone; borane derivatives such as tributylborane; carbon tetrabromide, carbon tetrachloride, 1,1,2,2-tetrabromoethane,
Tribromophenol, trichlorethylene, bromotrichloromethane, tribromomethane, 3-chloro-1-halogenated hydrocarbons such as propene, chloral, aldehydes such as furaldehyde, alkyl mercaptans C ₁ -C _18; thiophenol, Aromatic mercaptans such as toluene mercaptan; mercaptoacetic acid; mercaptoacetic acid
C ₁ -C ₁₀ alkyl esters; C ₁ hydroxamate Le alkyl mercaptans -C _12; Binen, terpenes such Tapinoren; can be exemplified.

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 contains the acrylic (co) polymer in an amount of from 20 to
In order to obtain the hot-melt pressure-sensitive adhesive composition of the present invention containing 90% by weight, an organic solvent is removed from the (co) polymer solution by a known method such as distillation to remove the acrylic (co) polymer. ) Isolate the polymer.

The active energy ray-curable hot melt pressure-sensitive adhesive composition of the present invention comprises the acrylic (co) polymer (A) described above.
In addition, a compound having two or more acryloyl groups, methacryloyl groups, allyloxy groups and / or methallyloxy groups in one molecule and having a molecular weight of less than 1000 (hereinafter sometimes abbreviated as a polyunsaturated compound) And one or more compounds (B) selected from the group of

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

Such polyunsaturated compounds include, for example, ethylene glycol diglycidyl ether diacrylate,
Polyepoxy such as diethylene glycol diglycidyl ether dimethacrylate, triethylene glycol diglycidyl ether dimethacrylate, propylene glycol diglycidyl ether diacrylate, sorbitol tetradiglycidyl ether tetramethacrylate, glycerol triglycidyl ether triacrylate, and bisphenol A diglycidyl ether diacrylate Compound poly (meth) acrylates; 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 hydroxyvivalate, trimethylolethane trimethacrylate, trimethylolpropane triacrylate,
Ethoxylated trimethylolpropane triacrylate,
Poly (meth) acrylates of polyols such as pentaerythritol triacrylate, pentaerythritol tetraacrylate, and dipentaerythritol hexaacrylate; for example, (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 composition. Each of these alone,
Alternatively, two or more kinds of these polyunsaturated compounds can be used as a mixture, but two or more kinds of these polyunsaturated compounds are preferably used for reasons such as a good balance between pressure-sensitive adhesiveness, 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 hot melt pressure-sensitive adhesive composition of the present invention comprises the acrylic (co) polymer (A) described above.
Together with the polyunsaturated compound (B), a compound (C) represented by the following general formula: CH ₂ CRCR ¹ -R ³ -CR ³ OHOH ₂ . Is included). here
R ¹ and R ² are each independently H or CH ₃ , preferably H,
R ³ is a C _{4 to} C ₁₆ linear or branched alkylene group, and is preferably C _{4 to} C ₁₂ from the viewpoints of low volatilization, pressure-sensitive adhesiveness of the obtained composition, and good adhesion. Is a linear alkylene group.

Specific examples of such a compound (C) include, for example,
Examples thereof include 1,9-decadiene and 1,13-tetradecadiene.

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 too small below the lower limit, the effect of lowering the viscosity at the time of application of the obtained adhesive composition is insufficient, which is not preferable, and if the amount exceeds the upper limit, the cohesive strength is too large. May decrease, which is not preferred.

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, it is preferable to use those having a melting point of room temperature (about 20 ° C.) or lower and a boiling point of 160 ° C. or higher as the components (B) and (C).

The active energy ray-curable hot melt pressure-sensitive adhesive composition of the present invention is oxidized together with the acrylic (co) polymer (A), polyunsaturated compound (B) and diene monomer (C). The inhibitor (D) is contained in an amount of 0.1 to 1 part by weight based on 100 parts by weight of the (co) polymer (A). If the amount of the antioxidant (D) exceeds the upper limit, the curing reaction by irradiation with active energy rays is difficult to proceed sufficiently, and the cohesive strength and adhesive strength of the obtained pressure-sensitive adhesive layer may be insufficient. On the other hand, when the amount is less than the lower limit, the effect of adding the component (D) is hardly exhibited, and the acrylic (co) polymer is thermally degraded at the time of heat coating, or the polyunsaturated compound is thermally polymerized. In some cases, an excellent pressure-sensitive adhesive layer may not be obtained, and it may not be possible to reuse the heated hot-melt pressure-sensitive adhesive composition.

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-tert-butyl-4'-hydroxyphenyl) propionate, pentaerythritol tetrakis [3- (3', 5-di-tert-butyl-4'-hydroxyphenyl) propionate], 2, 2'-methylenebis (6
Phenolic antioxidants such as (-t-butyl-4-methylphenol) monoacrylate are preferable because they have excellent heat stability, oxidation stability, heat discoloration resistance, and evaporation resistance.
Most preferred is 2'-methylenebis (6-t-butyl-4-methylphenol) monoacrylate from the viewpoint of less coloring of the resulting pressure-sensitive adhesive layer.

The active energy ray-curable hot-melt pressure-sensitive adhesive composition of the present invention may be prepared by using the acrylic (co) polymer (A), polyunsaturated compound, A photopolymerization initiator can be used in addition to (B), the diene monomer (C) and the antioxidant (D).

Examples of the photopolymerization initiator include diacetyl, benzyl, benzophenone, benzoin, ω-bromoacetophenone, chloroacetone, benzoquinone, anthraquinone, 2-ethylanthraquinone, benzoin 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 composition of the present invention is selected from the group consisting of water and the organic solvent used for the solution polymerization of the acrylic (co) polymer within a range not impairing the excellent effects of the present invention. A volatile solvent having a boiling point of 250 ° C. or less in a normal state may be contained, but the content of these solvents is limited to the acrylic (co) polymer (A), the polyunsaturated compound (B) and the diene monomer. It is good to be 10 parts by weight or less, preferably 5 parts by weight or less, particularly preferably 1 part by weight or less based on a total of 100 parts by weight of the body (C).

The pressure-sensitive adhesive composition of the present invention may further comprise, if necessary, for example, coumarone-indene resin, terpene-phenol resin, pt-butylphenol-acetylene resin, phenol-formaldehyde resin, terpene resin, xylene. Tackifying resin such as formaldehyde resin, petroleum hydrocarbon resin, hydrogenated hydrocarbon resin, rosin derivative, turpentine resin; for example, ethylene-vinyl acetate copolymer resin, ethylene-acrylic copolymer resin, ethylene Other modifying resins such as vinyl acetate-acrylic copolymer resins; and the like. The added amount of these resins is 10% in total of the components (A) to (C).
0 parts by weight, tackifying resin, for example, 0 to 60 parts by weight, particularly 0 to 40 parts by weight; other modifying resins, for example, 0 to 50 parts by weight, particularly 0 to 20 parts by weight; There should be.

In addition to these, the pressure-sensitive adhesive composition of the present invention may be optionally used, for example, a phthalate ester such as dioctyl phthalate, a phosphate ester such as tricresyl phosphate, or a plasticizer such as polybutene or process oil. Agent;
For example, organic or inorganic coloring agents such as titanium oxide, carbon black, and phthalocyanine blue; inorganic fillers such as clay, talc, calcium carbonate, silica, aluminum hydroxide, and glass powder;
Known additives such as an ultraviolet absorber, a preservative, and the like may be added.

As described above, the pressure-sensitive adhesive composition of the present invention is preferably an acrylic (co) polymer obtained by solution polymerization in an organic solvent having a boiling point of 60 to 100 ° C., such as ethyl acetate.
In the polymer solution, a polyunsaturated compound (B) such as trimethylolpropane triacrylate, ethoxylated trimethylolpropane triacrylate, for example, 1,9
A diene monomer (C) such as decadiene, e.g.
2'-methylenebis (6-t-butyl-4-methylphenol) monoacrylate [trade name: Sumilizer GM,
(Sumitomo Chemical Industry Co., Ltd.) and, if necessary, for example, a photopolymerization initiator such as benzoin ethyl ether and the like. By heating and further removing the organic solvent using, for example, drying under reduced pressure, and, if necessary, adding and mixing a tackifying resin, a modifying resin, a plasticizer, and a pigment. be able to.

The active energy ray-curable hot-melt pressure-sensitive adhesive composition of the present invention is generally hot-melted according to a known method, applied to various substrates at an appropriate thickness, and then formed. The layer can be cured by irradiating it with an active energy ray to such an extent that the pressure-sensitive adhesive property of the layer is not lost, thereby forming 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,
α-rays, β-rays, ionizing radiations such as γ-rays or X-rays, such as problems with equipment, ease of handling, and the use of a pressure-sensitive adhesive composition that has better storage stability, etc. From the viewpoint, the use of an electron beam is preferred.

The term "to the extent that the pressure-sensitive adhesive property is not lost" means that the value of the pressure-sensitive adhesive property is 100 g / in accordance with the method of JIS Z-0237 as described later.
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 composition 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 pressure-sensitive adhesiveness, the adhesive force and the cohesive force The measuring method 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 composition of the present invention is preferably 10,000 cps or less.

(2) Thermal stability of composition The energy-ray-curable hot-melt pressure-sensitive adhesive composition is put 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 was coated with an electron beam-curable hot melt pressure-sensitive adhesive composition melted at 150 ° C to a thickness of about 25 µm. And irradiating the surface of the obtained composition-specific layer with an electron beam of 4 Mrad,
The composition was cured to obtain a test pressure-sensitive adhesive sheet.

(4) Measurement of pressure-sensitive adhesiveness Polished with water-resistant abrasive paper of # 280 specified in JIS R-6253
The test pressure-sensitive adhesive sheet prepared in (3) was pressed on a stainless steel sheet of SUS 304 according to the method of JIS Z-0237, and after 20 minutes under the conditions of 20 ° C., 65% RH, and a peeling speed of 300 mm / min. The peel strength (g / 25 mm) is measured. The value of the pressure-sensitive adhesiveness is preferably 600 g / 25 mm or more, and 100 g / 25 mm or more.
It is particularly preferred that it is 0 g / 25 mm or more.

(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
Using the pressure-sensitive adhesive sheet for test prepared in (3) according to the method of JIS Z-0237, using γ ₀ = 43 dyn / cm according to the method specified in K-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 1000 g / 25 mm or more, and particularly preferably 1400 g / 25 mm or more.

(6) Measurement of cohesive strength Polished with # 280 water-resistant abrasive paper specified in JIS R-6253
The test pressure-sensitive adhesive sheet prepared in (3) was adhered to a stainless steel plate of SUS 304 so that the adhered area became 25 × 25 mm ² , and was pressure-bonded by reciprocating a 2 kg roller once.

A 1 kg static load is applied to the sample in an atmosphere of 40 ° C. × 30% RH, and the time until the load drops is measured. The cohesive force is preferably at least 100 minutes, particularly preferably at least 500 minutes.

(7) Measurement of curved surface adhesiveness 10 mm × 20 from the test pressure-sensitive adhesive sheet created in (3)
mm test piece was cut out, affixed to a φ10 mm polyethylene rod [of the same material as the polyethylene used in (5)] and left at 20 ° C. and 65% RH for 24 hours. Observe the floating from the stick.

 ；: No lifting ；: slightly floating ×: completely floating It is necessary that the surface adhesion be ○.

Reference Example 1 In a separable flask equipped with a reflux condenser, a thermometer, a stirrer, and a sequential dropping apparatus, an organic solvent for initial addition and 80 parts by weight of ethyl acetate (EAc) and azobisisobutyronitrile as a polymerization initiator were added. (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 2.5 parts by weight of 1,9-decadiene (DDE) as a diene monomer The parts were mixed to obtain an electron beam-curable hot melt pressure-sensitive adhesive composition. Table 2 shows the measurement results of various physical properties of the obtained composition.

Example 2 and Comparative Examples 1 and 2 An electron beam-curable hot melt pressure-sensitive adhesive composition 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 measurement results of the composition and various physical properties of the obtained composition.

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

Example 3 and Comparative Example 4 An electron beam-curable hot melt was prepared in the same manner as in Example 1, except that 1,13-tetradecadiene (TDDE) or 2-ethylhexyl acrylate (2EHA) was used instead of DDE. A pressure-sensitive adhesive composition was obtained. Table 2 shows the measurement results of the composition and various physical properties of the obtained composition.

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, an electron beam-curable hot melt solution was used. A pressure-sensitive adhesive composition was obtained. Table 2 shows the measurement results of the composition and various physical properties of the obtained composition.

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

Examples 4 and 5 An electron beam-curable hot melt pressure-sensitive composition was obtained in the same manner as in Example 1 except that the acrylic copolymer solution of Reference Example 4 or 5 was used instead of the acrylic copolymer solution of Reference Example 1. An adhesive composition was obtained. Table 2 shows the measurement results of the composition and various physical properties of the obtained composition.

Continuation of the front page (56) References JP-A-58-108275 (JP, A) JP-A-2-276879 (JP, A) JP-A 1-29746 (JP, A) (58) Fields investigated (Int) .Cl. ⁶ , DB name) C09J 4/06

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, comprising: an active energy ray-curable hot melt pressure-sensitive adhesive composition.