JPH03119081A - Hot-melt pressure-sensitive adhesive curable with actinic energy ray - Google Patents

Abstract

PURPOSE:To provide the subject adhesive containing an acrylic (co)polymer, a compound having acryloyl group and allyloxy group, etc., a specific compound and an antioxidant, keeping excellent physical properties such as pressure- sensitive adhesivity and having improved adhesivity to nonpolar plastics. CONSTITUTION:The objective composition contains (A) 100 pts.wt. of an acrylic (co)polymer having a weight-average molecular weight of 50,000-500,000 measured by GPC, (B) 1-10 pts.wt. of one or more compounds selected from a group of compounds having >=2 acryloyl group, methacryloyl group, allyloxy group and/or methallyloxy group in one molecule and having a molecular weight of <1,000, (C) 1-10 pts.wt. of a compound of formula (R<1> is H or CH3; R<2> is 2-6C alkylene: n is 1-30; R<3> is 1-12C alkyl, 6-18C phenyl or alkylphenyl) and (D) 0.1-1 pt.wt. of an antioxidant.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to an active energy ray-curable hot-melt pressure-sensitive adhesive, and more specifically, to an acrylic (co)polymer having a specific molecular weight. , a specific amount of one or more compounds selected from the group of compounds in a specific molecular weight range that have two or more specific ethylenically unsaturated bonds in one molecule, one ψ(meth)acryloyl group in one molecule, The present invention relates to an active energy ray-curable hot-melt pressure-sensitive adhesive characterized by containing a specified amount of a compound containing a (poly)oxyalkylene y chain and a specified amount of an antioxidant.

[Conventional technology and its problems]

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

For example, JP-A No. 50-136328 describes “acrylic acid alkyl ester (alkyl group having 3 to 10 carbon atoms)”
50 to 100 parts by weight, vinyl acetate 20 to 100 parts by weight,
A copolymer mainly composed of 3 to 15 parts by weight of a vinyl monomer having a polar group selected from the group of Cool, CN, CONHz and their derivatives in the side chain is coated or impregnated onto a support sheet, and sensitized. "Pressure-sensitive adhesive tape" characterized in that it is irradiated with 3 to 35 Mrad of ionizing radiation within a range that maintains pressure-adhesive properties to generate appropriate crosslinking.

However, in the above proposal, "pressure-sensitive adhesive tape"
Generally, irradiation with relatively high doses of ionizing radiation is required to impart sufficient cohesive strength to the pressure-sensitive adhesive layer, but in that case, the pressure-sensitive adhesive properties of the pressure-sensitive adhesive layer are extremely reduced. It is not easy to make the pressure-sensitive adhesive tape maintain various properties such as heat resistance, pressure-sensitive adhesiveness, adhesive force, and cohesive force in a well-balanced manner. Furthermore, if the irradiation dose of the ionizing radiation is too large, the "support sheet" may be deteriorated, and the material of the support sheet has its own limitations.

Furthermore, in order to use the proposed copolymer as a hot-melt pressure-sensitive adhesive, it must be heated to a fairly high temperature to ensure coating viscosity, which may cause thermal discoloration and thermal deterioration of the copolymer. Easy to cause problems.

Furthermore, if an organic solvent is used to avoid thermal coloring and thermal deterioration, the organic solvent will volatilize into the atmosphere during coating, deteriorating the working environment and easily causing problems such as air pollution.

Next, JP-A No. 59-176370 states, ``To 100 parts by weight of a copolymer with a molecular weight of 100,000 to 60,000, the main component being an alkyl ester of acrylic acid or methacrylic acid,
Molecular weight: 1000 to 1,000 having two or more unsaturated bonds in one molecule that can cause radical crosslinking by ultraviolet rays or electron beams
A pressure-sensitive adhesive composition capable of radical crosslinking with ultraviolet rays or electron beams, which is formed by blending 1 to 50 parts by weight of a 20,000 oligomer and 0 to 10 parts by weight of a photosensitizer. ” has been proposed.

However, the oligomer used in the second proposal above 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, so it is difficult to apply the proposed composition. The viscosity tends to be high during coating, and lowering the viscosity during coating requires heating at a higher temperature.
The oligomer is likely to undergo thermal polymerization, thermal deterioration, etc., resulting in coloring of the resulting pressure-sensitive adhesive layer, and maintaining the balance of various properties such as heat resistance, pressure-sensitive adhesion, adhesive strength, and cohesive force. This tends to be difficult. Another problem is that it is difficult to reuse the composition once it has been heated and melted.

The present inventors have carried out research to solve the problems of these conventional active energy ray-curable pressure-sensitive adhesives, and as a result, we have found that acrylic (co)polymers with a specific molecular weight have a
By containing a compound in a specific molecular weight range having two or more ethylenically unsaturated bonds in the molecule and a specific amount of antioxidant, the above-mentioned problems can be solved and an excellent pressure-sensitive active energy ray-curable hot melt can be obtained. He discovered that it was possible to obtain an adhesive composition and filed a patent application (Japanese Patent Application No.
No. 9965). Although the pressure-sensitive adhesive composition of the present invention is considerably superior to conventional ones, there are cases where a further increase in coating speed is required for the purpose of higher productivity, and such In some cases, further reduction in the viscosity of the composition is required. In addition, the hot melt pressure sensitive adhesive composition of Hikari Invention tends to lack pressure sensitive adhesive properties compared to solvent-based pressure sensitive adhesives, and it also has poor adhesive strength, especially for non-polar plastics such as polyethylene. There was also the problem that the adhesion to the adhesive was insufficient.

On the other hand, in order to reduce the viscosity of pressure-sensitive adhesives during coating, it has been known to use (meth)acrylic monomers such as n-butyl acrylate as diluents. , Japanese Patent Publication No. 58-108275
In the publication, [-formula CHz = CHCQOR'
(However, R1 is an alkyl group having 2 to 14 carbon atoms) or a copolymer of the acrylic esters having different R1, and has a molecular weight s, ooo to 300,000. Combined 100 parts by weight, - formula CHZ = CHC0OR" (However, R2
is an alkyl group having 2 to 14 carbon atoms) and 0.01 to 10 parts by weight of an acrylic acid ester having two or more acryloyl groups in one molecule. An ionizing radiation-curable adhesive composition. ” is disclosed.

However, although the above proposed adhesive composition can reduce the viscosity during coating, the acrylic monomer used is generally highly volatile, has a strong odor, and is highly flammable. In addition to significantly deteriorating the working environment, there are many problems during storage, such as changes in the composition and viscosity of the adhesive composition over time due to the volatilization of the monomer, and the risk of fire. However, the adhesion to non-polar plastics is also not sufficient.

As a result of further research following the previous invention, the present inventors have further added, for example, ethylene glycol methyl ether acrylate and tetraethylene glycol to the active energy ray-curable hot melt pressure sensitive adhesive composition of the invention. Melt viscosity during coating can be lowered by containing a specific amount of a specific compound containing one (meth)acryloyl group and (poly)oxyalkylene chain in one molecule, such as nonylphenol ether acrylate. From the beginning, various excellent physical properties such as pressure-sensitive adhesiveness and adhesive strength (SUS) possessed by the pressure-sensitive adhesive composition of the previous invention can be maintained, or can be improved between layers, and further,
The present invention was completed based on the discovery that the adhesion to non-polar plastics can also be significantly improved.

[Means for solving problems]

The present invention relates to the following A-D, A, acrylic (co)polymer 10, which has a weight average molecular weight of 50,000 to 500,000 by GPC.
0 parts by weight, B, one or two selected from the group of compounds having two or more acryloyl groups, methacryloyl groups, allyloxy groups and/or methacryloxy groups in one molecule, and whose molecular weight is less than 1000. 1 to 10 parts by weight of a compound of C0 or more, 1 to 10 parts by weight of a compound represented by the following general formula (1), CHz"CR'COO(R"0)nR3... and D, antioxidant 0 The object of the present invention is to provide an active energy ray-curable hot-melt pressure-sensitive adhesive characterized by containing .1 to 1 part by weight.

The present invention will be explained in detail below.

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

The above acrylic (co)polymer (A) includes the following (a)
) ~ (C), (a) -Formula CHz=CHCOOR' (However, R
4 is an acrylic acid ester monomer represented by (02 to C11l linear or branched alkyl group),
For a monomer whose homopolymer has a glass transition point of 120°C or less, (b) a monomer having at least one functional group in addition to a radically polymerizable unsaturated group, if necessary. and (C) a monomer other than (a) and (a) that can be copolymerized with (a) and (b) above, an acrylic (co)polymer obtained by (co)polymerizing It is preferable to use it from the viewpoint of a good balance of adhesive side force, cohesive force, and pressure-sensitive adhesive property of the resulting pressure-sensitive adhesive layer.

The acrylic acid ester monomer in (a) above has the formula C)
Iz=CHCOOR', the homopolymer has a gas phase transition degree of 120°C or less, and R4 of the acrylic acid ester monomer (a) is C! 'wc+t, preferably 02 to C+Z, represents a straight-chain or branched alkyl group.

Examples of such groups R4 include ethyl group, n-propyl group, n-butyl group, isobutyl group, n-hexyl group,
Examples include n-octyl group, i-octyl group, 2-ethylhexyl group, i-nonyl group, and specific examples include ethyl acrylate, n-propyl acrylate, n-butyl acrylate, i-butyl acrylate, Examples include n-hexyl acrylate, n-octyl acrylate, i-octyl acrylate, 2-ethylhexyl acrylate, and i-nonyl acrylate.

The amount of the acrylic acid ester monomer (a) used is %
An amount of about 100% is suitable. The acrylic acid ester monomer (
By appropriately selecting and utilizing a) within the above usage amount range, a good balance of adhesive strength, pressure-sensitive adhesiveness and cohesive strength can be achieved.

In addition to the radically polymerizable unsaturated group (b), monomers having at least one functional group may include, for example, a carboxyl group, an amide group, or a substituted amide group, Examples include monomers having an amino group or a substituted amino group, a hydroxyl group, a mercapto group, etc., and in the present invention, one or more monomers may be appropriately selected and used from these. Specific examples of these monomers include acrylic acid, methacrylic acid, itaconic acid, maleic acid, maleic anhydride, fumaric acid, crotonic acid, and citraconic acid (preferably acrylic acid, methacrylic acid, and itaconic acid). carboxyl group-containing monomers such as acid); for example, amide group-containing monomers or substituted amide group-containing monomers such as acrylamide, methacrylamide, N, N-dimethylacrylamide, N-methylacrylamide (preferably acrylamide, methacrylamide) For example, aminoethyl acrylate, N,N-dimethylaminoethyl acrylate, N.

N-diethylaminoethyl acrylate, N,N-dimethylaminoethyl MEC 1 root, N,N-diethylaminoethyl methacrylate, (preferably N,N
-dimethylaminoethyl methacrylate, N,N-diethylaminoethyl methacrylate); for example, 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, 2-hydroxyethyl methacrylate, allyl alcohol, Methallyl alcohol (preferably 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, 2-hydroxyethyl methacrylate, 2-hydroxyethyl acrylate, 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate,
-hydroxypropyl methacrylate); for example, mercapto group-containing monomers such as vinyl mercaptan and allyl mercaptan; and the like. Among these monomers (b), it is preferable to use at least one monomer selected from the group of carboxy group-containing monomers, amide group-containing monomers, and substituted amino group-containing monomers. Particularly preferred.

The amount of the monomers (a) to (a) to (a) to be used is as follows:
For example, 0.5 to 15% by weight out of the total 100% by weight of C)
, preferably about 1 to 10% by weight.

If the amount of monomer (c) used is below the upper limit, the pressure-sensitive adhesive properties of the resulting active energy ray-curable hot-melt pressure-sensitive adhesive will not be too low; It is preferable that a good balance between adhesive strength and cohesive strength can be achieved by adjusting the amount to 0.5% by weight or more.

Furthermore, as the comonomer (C) which is copolymerizable with the monomers (a) and (b) above and other than the monomers (a) and ω), for example, , methyl acrylate, t
-butyl acrylate, cyclohexyl acrylate,
Acrylic acid ester monomers other than the above (a) such as stearyl acrylate; for example, methyl methacrylate,
Ethyl methacrylate, n-butyl methacrylate, i
-butyl methacrylate, t-butyl methacrylate,
n-hexyl methacrylate, cyclohexyl methacrylate, n-octyl methacrylate, i-octyl methacrylate, 2-ethylhexyl methacrylate, i
-Methacrylic acid ester monomers such as nonyl methacrylate, n-dodecyl methacrylate, i-dodecyl methacrylate, and stearyl methacrylate; For example, saturated fatty acid vinyl ester monomers such as vinyl formate, vinyl acetate, vinyl propionate, and vinyl versatate; , dibutyl maleate, dibutyl fumarate, dibutyl itaconate, dioctyl maleate, dioctyl fumarate, dioctyl itaconate, etc. , aromatic vinyl monomers such as α-methylstyrene, vinyltoluene, and ethylvinylbenzene; for example, vinyl cyanide monomers such as acrylonitrile and methacrylaterile; and the like.

Preferably, the amount is about 3 to F+-4iP-8% by weight. The amount of comonomer (C) to be used cannot be unambiguously determined as it may vary depending on the type of comonomer, but it is important to consider the balance between adhesive strength and pressure-sensitive adhesiveness, and the balance between these and cohesive strength. The amount can be appropriately selected within the above range to meet such purpose. If the amount of the comonomer (C) used is below the upper limit of the above-mentioned range, the pressure-sensitive adhesiveness will not become too low, and an appropriate balance between adhesive strength and pressure-sensitive adhesiveness will be maintained. Therefore, when using the comonomer (C), it is preferable to appropriately select and use the amount within the above range.

The glass transition point (hereinafter sometimes abbreviated as Tg) of the acrylic (co)polymer that is the main component of the active energy ray-curable hot melt pressure-sensitive adhesive of the present invention is preferably -20°C or lower. , more preferably -30°C or lower.

Temperatures below this upper limit are preferred because they have excellent pressure-sensitive adhesive properties.

) is 50,000 to 500,000, preferably 100,000 to 400,000. Below this lower limit, the resulting pressure-sensitive adhesive layer may lack adhesive strength and cohesive force, while above this upper limit, a higher melting temperature may be required to obtain a suitable coating viscosity. For this reason, thermal deterioration of acrylic (co)polymers and thermal polymerization of compounds that "have two or more acryloyl groups, methacryloyl groups, allyloxy groups and/or metalryloxy groups in one molecule" as described later, etc. This is not desirable because it 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: Made of aluminum foil with a thickness of about 0.05 mm, inner diameter of about 5 m.
, a cylindrical cell with a depth of about 511n, acrylic (common)
Approximately 10 μm of a 50% by weight organic solvent solution sample of the polymer was weighed out, dried at 100° C. for 2 hours, and used as a measurement sample. Seiko Electronics Chest Back 5SC-5000 Differential Scanning Calorimeter (Differential ScanningC
measurement and determination using a temperature increasing rate of 10°C/min from -150°C.

The method of polymerizing the acrylic (co)polymer of the present invention is not particularly limited (well-known methods such as solution polymerization and emulsion polymerization can be used), but the (co)polymer mixture obtained by polymerization may be In producing an active energy ray-curable hot-melt pressure-sensitive adhesive, it is preferable to employ solution polymerization, which is a relatively simple process and can be carried out in a short period of time.

Solution polymerization is generally performed by adding a predetermined organic solvent, a monomer compound, a polymerization initiator, and an optional chain transfer agent to the polymerization system, and then polymerizing the polymer for several times while stirring in a nitrogen stream or at the reflux temperature of the organic solvent. The reaction is carried out by heating for a period of time, and in this case, a solvent, a monomer, a polymerization initiator and/or a chain transfer agent may be sequentially added.

Examples of the above organic solvent include aromatic hydrocarbons such as benzene, toluene, xylene, and aromatic naphtha; n-
Aliphatic or alicyclic hydrocarbons such as hexane, n-hebutane, n-octane, i-octane, n-decane, dipentene, petroleum spirit, petroleum naphtha, turpentine; ethyl acetate, n-butyl acetate , n-amyl acetate, 3-methoxybutyl acetate, methyl benzoate, cellosolve acetate, butyl cellosolve acetate and other esters; acetone, methyl ethyl ketone, methyl isobutyl ketone, isophorone, cyclohexanone, methyl cyclohexanone and other ketones;
Ethers such as methyl cellosolve, ethyl cellosolve, butyl cellosolve; examples: tlf methyl alcohol, ethyl alcohol, n-propyl alcohol, i-propyl alcohol, n-butyl alcohol, i-butyl alcohol, s-7' tyl alcohol, t-butyl Alcohols such as alcohol; etc. can be mentioned.

These organic solvents can be used alone or in a mixture of two or more.

In addition, since the active energy ray-curable hot-melt pressure-sensitive adhesive of the present invention needs to be substantially solvent-free,
Among these organic solvents, the organic solvent is volatilized from the obtained FJ polymer solution (9, which is easy to isolate the polymer).
It is preferable to use an organic solvent with a boiling point of 50 to 150°C, particularly 60 to 100°C, and among them, organic solvents such as n-hexane, ethyl acetate, acetone, methyl ethyl ketone, methyl alcohol, and n-propyl alcohol are used. It is particularly preferred to use

Examples of the polymerization initiator include benzoyl peroxide, lauroyl peroxide, caproyl peroxide, Jimmy propyl peroxydicarbonate, di-2-ethylhexyl peroxydicarbonate,
Organic peroxides such as t-butyl peroxyvivalate; for example, 2.2'-azobis-1-butyronitrile; 2.
2'-azobis-2,4-dimethylvaleronitrile, 2
．． an azo compound such as 2'Asohis-4-methoxy-2,4-dimethylvaleronitrile; etc. alone or in combination, about 0.01 to 0.3 parts by weight, more preferably about 0.
It is preferable to use 01 to 0.15 parts by weight.

Further, as the chain transfer agent, for example, cyanoacetic acid;
Cyanoacetic acid alkyl esters with alkyl groups C8 to C8; bromoacetic acid; bromoacetic acid esters with alkyl groups C1 to C8; anthracene, phenanthrene, fluorene,
9 Aromatic compounds such as niphenylfluorene; p-nitroaniline, nitrobenzene, dinitrobenzene, p
- Aromatic nitro compounds such as nitrobenzoic acid, p-nitrophenol, p-nitrotoluene; benzoquinone, 2
．． Benzoquinone derivatives such as 3,5.6-tetramethyl-p-benzoquinone; poran derivatives such as tributylborane; carbon tetrabromide, carbon tetrachloride, 1.1.2.2-tetrabromoethane, tribromoethylene, Trichlorethylene, bromotrichloromethane, tribromomethane, 3-
Halogenated hydrocarbons such as chloro-1-propene; aldehydes N such as chloral and furaldehyde; Cl=C+
s alkyl mercaptans; aromatic mercaptans such as thiophenol and toluene mercaptan; mercaptoacetic acid; C1-C8° alkyl ester of mercaptoacetic acid [;C, ~CI! hydroxylalkyl mercaptans; terpenes such as pinene and terpircin; and the like.

Preferably, it is a stationary part.

The polymerization temperature is generally in the range of about 30-180'C1, preferably about 60-150'C.

The thus obtained (co)polymer solution suitably used in the present invention usually contains the acrylic (co)polymer in an amount of 20 to 20%.
In order to obtain the hot melt bad pressure adhesive of the present invention, the organic solvent is removed from the acrylic (co)polymer solution by a known method such as distillation.
The polymer is isolated.

The active energy ray-curable hot melt pressure-sensitive adhesive of the present invention contains two acryloyl groups, methacryloyl groups, allyloxy groups and/or metalryloxy groups in one molecule together with the acrylic (co)polymer (A). containing one or more compounds (B) selected from the group of compounds (hereinafter sometimes abbreviated as polyunsaturated compounds) having a molecular weight of less than 1,000 and a molecular weight of less than 1000. It is what it is.

If a polyunsaturated compound (B) with a molecular weight of 1,000 or more is used, the melt viscosity at the same temperature will increase, so a higher melting temperature will be required to obtain a suitable coating viscosity, but in that case, the acrylic This is not preferable since thermal deterioration of the system (co)polymer and thermal polymerization of the polyunsaturated compound may occur.

Examples of such polyunsaturated compounds include ethylene glycol diglycidyl ether diacrylate, diethylene glycol diglycidyl ether dimethacrylate, triethylene glycol diglycidyl ether dimethacrylate, propylene glycol diglycidyl ether diacrylate, and sorbitol tetraglycidyl ether tetramethacrylate. , glycerol triglycidyl ether triacrylate, bisphenol A diglycidyl ether diacrylate, and other poly(meth)acrylates of polyepoxy compounds; 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, hydroxypivalate neopentyl glycol diacrylate, trimethylolethane trimethacrylate, trimethylolpropane triacrylate,
ethoxylated trimethylolpropane triacrylate,
Poly(meth)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, diallyl maleate; , diallyl fumarate, diallyl itaconate and other radically polymerizable dicarboxylic acids (
meth)allyl ester; for example, diallyl phthalate,
Examples include (meth)allyl esters of polycarboxylic acids other than those mentioned above, such as triallyl cyanurate and triallyl isocyanurate.

Among these polyunsaturated compounds (B), ease of acquisition,
From the viewpoint of a good balance of various physical properties of the resulting pressure-sensitive adhesive composition, it is preferable to use poly(meth)acrylate as a polyol, and each of these can be used alone or in a mixture of two or more types. However, it is preferable to use a mixture of two or more of these polyunsaturated compounds for reasons such as a good balance of pressure-sensitive adhesiveness, adhesive force, and cohesive force.

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 it is used in excess of the upper limit, the pressure-sensitive adhesive properties of the resulting pressure-sensitive adhesive layer may deteriorate, and if it is less than the lower limit, the effect of adding component (B) may be impaired, which is not preferable.

The active energy ray-curable hot-melt pressure-sensitive adhesive composition of the present invention, together with the acrylic (co)polymer (A) and polyunsaturated compound (B), has the following general formula (1), CHz=CR'C00-(R"0)-R'...
It contains a compound (C) represented by (1) (hereinafter sometimes abbreviated as oxyalkylene monomer). Here, R1 is H or cns, Rz is Ct
``' Straight chain or branched alkylene group of Cb, n is 1 to
An integer of 30, R3 is a C2-C+t straight or branched alkyl group or a C6xc, phenyl or alkylphenyl group.

Specific examples of such compound (C) include 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 Examples include methyl ether acrylate, polypropylene glycol (n-about 2.5) nonylphenol ether acrylate, and the like.

The amount of the compound (C) to be used is 1 to 10 parts by weight, preferably 2 to 8 parts by weight, based on 100 parts by weight of the acrylic (cofiltration aggregate (A)). If the amount is too low, the effect of reducing the viscosity of the resulting adhesive during application will be insufficient, and if it is too high, the pressure-sensitive adhesive properties and adhesive strength may decrease. This is not desirable.

Both of the above components (B) and (C) are acrylic (co)polymers (before active energy ray irradiation).
It acts as a diluent for A) to keep the viscosity at a moderately low level during coating, and polymerizes by itself when irradiated with active energy rays and/or undergoes a crosslinking reaction with the acrylic (co)polymer (A). It is preferable to use a material that can be turned into a solid resin. Therefore, it is preferable to use components (B) and (C) that have a melting point below room temperature (approximately 20°C) and a boiling point above 160°C, preferably above 200°C.

The active energy ray-curable hot-melt pressure-sensitive adhesive of the present invention contains the above-mentioned acrylic (co)polymer (A), polyunsaturated compound (B), and oxyalkylene monomer (C). The inhibitor (D) is added to the (co)polymer CA) 10
It contains 0.1 to 1 part by weight per 0 parts by weight. If the amount of the antioxidant (D) used exceeds the upper limit, the curing reaction due to active energy ray irradiation will be difficult to proceed sufficiently, and the resulting pressure-sensitive adhesive layer may lack cohesive strength and adhesive strength. On the other hand, below the lower limit, the effect of adding component (D) is unlikely to appear, and the acrylic (co)polymer may be thermally degraded during hot coating, or the polyunsaturated compound may undergo thermal polymerization. This is not preferable because it may not be possible to obtain an excellent pressure-sensitive adhesive layer, and the heated hot-melt pressure-sensitive adhesive may not be reusable.

The above-mentioned antioxidants generally include phenol-based, aromatic amine-based, sulfide-based, phosphite-based, etc. Among 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], 2.2' - Phenolic antioxidants such as methylenebis(6-t-butyl-4-methylphenol) monoacrylate are preferred because they have excellent thermal stability, oxidation stability, heat discoloration resistance, evaporation resistance, etc., and 2.2 '-methylenebis(6-t-butyl-4
-Methylphenol) monoacrylate is most preferred from the viewpoint of less coloring of the pressure-sensitive adhesive layer.

When the active energy ray-curable hot melt pressure sensitive adhesive of the present invention uses ultraviolet rays or the like as the active energy ray, the acrylic (co)polymer (A
), a polyunsaturated compound (B), an oxyalkylene monomer (C), and an antioxidant (D), a photopolymerization initiator can be used in combination.

Examples of the photopolymerization initiator include diacetyl, benzyl, benzophenone, benzoin, ω-bromoacetophenone, chloroacetone, benzoquinone, anthraquinone, 2-ethylanthraquinone, benzoin isopropyl ether, benzoin ethyl ether, and the amount used. can be exemplified in an amount of 0.1 to 15 parts by weight based on a total of 100 parts by weight of the above (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, within a range that does not impair the excellent effects of the present invention. It may contain a volatile solvent with a temperature of 250°C or less under normal conditions, but 10 parts by weight per 100 parts by weight of these solvents.
The amount is preferably at most 5 parts by weight, particularly preferably at most 1 part by weight.

The pressure-sensitive adhesive of the present invention may further include, for example,
Coumaron/indene resin, Tenipen phenolic resin,
pt-butylphenol/acetylene resin, phenol/formaldehyde resin, terpene resin, xylene Φ
Tackifier resins such as formaldehyde resins, petroleum hydrocarbon resins, hydrogenated hydrocarbon resins, rosin derivatives, turpentine resins; for example, ethylene-vinyl acetate copolymer resins, ethylene-acrylic copolymer resins, ethylene −
Other modifying resins such as vinyl acetate-acrylic copolymer resins can be added. The amount of these resins added is based on the total of 100 parts by weight of the components (A) to (C), and the tackifying resin, for example, 0 to 60 parts by weight, particularly 0 to 40 parts by weight; resin, e.g. 0-50
It is preferably about 0 to 20 parts by weight, particularly about 0 to 20 parts by weight.

In addition to these, the pressure-sensitive adhesive of the present invention may optionally contain, for example, a phthalate ester type such as dioctyl phthalate, a phosphate ester type such as tricresyl phosphate, a plasticizer such as polybutene, process oil, etc.; For example, organic or inorganic colorants such as titanium oxide, carbon black, phthalocyanine blue; for example, clay, talc,
Known additives such as inorganic fillers such as calcium carbonate, silica, aluminum hydroxide, and glass powder; photopolymerization initiation aids; ultraviolet absorbers; preservatives; and the like may be added.

As mentioned above, the pressure-sensitive adhesive of the present invention is preferably prepared by adding trimethylol 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. Polyunsaturated compounds (B) such as propane triacrylate, ethoxylated trimethylolpropane triacrylate, e.g. polypropylene glycol (n # 2.5) nonylphenol ether acrylate [Product name: Aroex M-1
Oxyalkylene monomers (C) such as 17, manufactured by Toagosei Kagaku Kogyo ■, for example, 2,2'-methylenebis(6
An antioxidant (D) such as -t-butyl-4-methylphenol) monoacrylate (trade name: Sumilizer GM, manufactured by Sumitomo Chemical) and, if necessary, a photopolymerization initiator such as benzoin ethyl ether. After adding and sufficiently stirring and mixing, the organic solvent used during solution polymerization is distilled off by heating, and the organic solvent is further removed using a method such as drying under reduced pressure, and if necessary, the tackifying resin, It can be manufactured by adding and mixing a modifying resin, a plasticizer, and a pigment.

The active energy ray-curable hot-melt pressure-sensitive adhesive of the present invention is thermally melted according to a generally known method, coated on various substrates to an appropriate thickness, and then a layer of the composition is formed. A pressure-sensitive adhesive layer can be formed on the base material by curing it by irradiating it with active energy rays to the extent that the pressure-sensitive adhesive properties of the base material are not lost. An example of the melting temperature is a temperature of about 100 to 180°C.

The active energy rays mentioned above include ultraviolet rays, electron beams, α
It refers to ionizing radiation such as rays, β-rays, γ-rays, or X-rays. The use of lines is preferred.

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

For example, when the active energy ray is an ultraviolet ray, the irradiation dose can be adjusted by adjusting the intensity of the lamp, the distance to the irradiated surface, and the irradiation time. Measured using a luminometer
0-10100O/c+a, preferably 50-500
It is better to set mJ to 10ff.

For example, in the case of an electron beam, the irradiation dose can be adjusted by adjusting the voltage, current, and irradiation time, and the dose is 0.5 to 10
Mrad is preferably 2 to 8 Mrad.

〔Example〕

Hereinafter, the present invention will be explained in more detail by giving reference examples and comparative examples as well as examples.

In addition, the method for measuring the viscosity at heat and the evaluation method for the thermal stability of the adhesive of the present invention, the method for preparing a pressure-sensitive adhesive sheet for testing the physical properties of the pressure-sensitive adhesive layer, and the method for measuring the pressure-sensitive adhesive property and adhesive force are as follows. It is as follows.

(1) Measurement of viscosity at heat Measurement is carried out using a viscosity needle Rheomat 30 (trade name) manufactured by Contrabass under the conditions of a cone plate PKI, a measurement temperature of 150° C., and a shear rate of 50 sec. The heat of the adhesive of the present invention Temporal viscosity is measured by placing a 10,000 cps energy ray-curable hot melt pressure sensitive adhesive in a glass bottle, sealing it, leaving it in a constant temperature bath at 150°C, and measuring the time until it loses fluidity.Thermal stability is 1. The duration is preferably 1 day or more, particularly 3 days or more.

(3) How to make a pressure-sensitive adhesive sheet for testing: Apply an electron beam-curable hot-melt pressure-sensitive adhesive melted at 150°C to a thickness of approximately 25μ on a 50μ polyethylene terephthalate film. Then, an adhesive sheet was obtained on the surface of the obtained adhesive layer.

(4) Measurement of pressure-sensitive adhesive property JIS Z-023 using the test pressure-sensitive adhesive sheet prepared in (3) on an SO5304 stainless steel plate polished with #280 water-resistant abrasive paper specified in JIS R-6253.
Press according to method 7, and after 20 minutes, 20°C, 65% R.
The peel strength (g/25 mm) is measured under the condition of H2 peel rate of 300 mm/a+in. The pressure-sensitive adhesive value is preferably 600 g/25 m or more,
Particularly preferred is 1000 g/25 mm or more.

(5) Measurement of adhesive strength SUS 304 stainless steel plate polished with #280 water-resistant abrasive paper specified in JIS R-6253 and polyethylene plate (γ
. ~43 dyn/cm) using the test pressure-sensitive adhesive sheet prepared in (3) according to the method of JIS Z-0237, and after 24 hours, the conditions were 20°C, 65% RH, and a peeling rate of 300-/n+in. Its peel strength (g/25
mm). Adhesive strength is 1000g/25
It is preferable that it is 1400g/25nrm or more.
The above is particularly preferable.

Reference Example 1 In a separable flask equipped with a reflux condenser, thermometer, stirrer, and sequential dropping device, 80 parts by weight of ethyl acetate (EAc) and abbisisobutyronitrile (as an organic solvent for initial addition and a polymerization initiator) were placed. AIBN) 0.012
5 parts by weight, then butyl acrylate (BA) 9
Add 25 parts by weight of a monomer mixture consisting of 4 parts by weight and 6 parts by weight of acrylic acid (AA) and heat until the internal temperature reaches 80-8.
Polymerization was carried out for 40 minutes while controlling the temperature to 5°C.

Next, while maintaining the internal temperature at 80 to 85°C, the remaining 75 parts by weight of the monomer mixture, 20 parts by weight of EAc, and AIB No.
A mixture for sequential addition consisting of 125 parts by weight was added dropwise over about 90 minutes, and the internal temperature was maintained at 80-85° for another 90 minutes.
C. to obtain an acrylic copolymer solution with a solid content of about 50% by weight. The Mw of this copolymer is 170,000, and the Tg is -42.
It was °C.

Reference Examples 2 to 5 Polymerization was carried out in the same manner as in Reference Example 1 using the same apparatus as in Reference Example 1 and using the monomer composition shown in Table 1, the mixture for initial addition, and the mixture for sequential addition. An acrylic copolymer solution was obtained. The Mw and Tg of this copolymer are shown in Table 1.

Example 1 To 100 parts by weight of the acrylic copolymer solution obtained in Reference Example 1, Sumilizer GM (trade name: manufactured by Sumitomo Chemical Co., Ltd.: 2.2'-methylenebis(6-t-
Butyl-4-methylphenol) monoacrylate (M
0.25 parts by weight of BPMA) was added and mixed, concentrated to a solid content of 99% by weight by drying under reduced pressure, and then 0.5 parts by weight of trimethylolpropane triacrylate (TMPTA) as a polyunsaturated compound and Photomer 41 were added.
49-3N (Product name: San Nopco chest: Ethoxylated trimethylolpropane triacrylate (TMFTf!A)
) ) as an oxyalkylene monomer, Aronic M-117 (trade name: Toagosei Chemical Industry ■
2.5 parts by weight of polypropylene glycol (nζ2.5) nonylphenol ether acrylate was mixed to obtain an electron beam-curable hot-melt pressure-sensitive adhesive. Table 2 shows the measurement results of various physical properties of the obtained adhesive.

Example 2 and Comparative Example 1.2 In Example 1, TMPTA and/or TMPT
An electron beam curable hot melt pressure sensitive adhesive was obtained in the same manner except that the amount of EA used was changed. Table 2 shows the composition of the adhesive obtained and the measurement results of various physical properties.

Comparative Example 3 An electron beam-curable hot melt pressure-sensitive adhesive 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 adhesive obtained and the measurement results of various physical properties.

Examples 3 to 6 and Comparative Example 4 In Example 1, Blenmar PME-100 (trade name; diethylene glycol methyl ether methacrylate manufactured by NOF ■) 2-MTA [trade name] was used instead of DE Aronic M-117 (trade name). Name: Osaka Organic Chemical Industry■
Manufactured by: ethylene glycol methyl ether acrylate]
, Light Acrylate BO-A C Product name: Kyoeisha Yushi Kagaku Kogyo Chest: Ethylene glycol n-butyl ether acrylate], Aloex M-113 (Product name: Toagosei Chemical Co., Ltd.: Tetraethylene glycol nonylphenol ether acrylate) or An electron beam-curable hot melt pressure-sensitive adhesive was obtained in the same manner except that 2-ethylhexyl acrylate (2EHA) was used.

Table 2 shows the composition of the adhesive obtained 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, electron beam curable hot melt was prepared. A pressure sensitive adhesive M product was obtained. Table 2 shows the composition of the adhesive obtained and the measurement results of various physical properties.

Comparative Example 7 An electron beam curable hot melt window pressure adhesive was obtained in the same manner as in Example 1 except that no antioxidant was used.

Table 2 shows the composition of the adhesive obtained and the measurement results of various physical properties.

Examples 7 and 8 Electron beam-curable hot melt adhesives were prepared 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. A pressure adhesive was obtained. Table 2 shows the composition of the adhesive obtained and the measurement results of various physical properties.

hand Continued Before Positive book December 15, 1999

Claims (1)

[Scope of Claims] [1] The following A to D, A, 100 parts by weight of an acrylic (co)polymer having a weight average molecular weight of 50,000 to 500,000 by GPC, B, 1 One or more compounds 1 to 10 selected from the group of compounds having two or more acryloyl groups, methacryloyl groups, allyloxy groups and/or metalryloxy groups in the molecule and having a molecular weight of less than 1000. Parts by weight, C, 1 to 10 parts by weight of a compound represented by the following general formula (1), CH_2=CR^1COO-(R^2O)_n-R^3
...(1) However, R^1 is H or CH_3, R^2 is C
_2 to C_6 straight chain or branched alkylene group, n is 1
An integer of ~30, R^3 represents a linear or branched alkyl group of C_1 to C_1_2 or a phenyl group or alkylphenyl group of C_6 to C_1_0. and an active energy ray-curable hot melt pressure-sensitive adhesive, comprising: D, 0.1 to 1 part by weight of an antioxidant.