JPH0350213A - Photocurable adhesive composition - Google Patents

Abstract

PURPOSE:To obtain the title composition of improved tackiness and adhesiveness by adding a polyisocyanate to a resin having an ethylenically unsaturated group as a side chain, obtained by reacting a specified rubberlike polymer with a cyclic acid anhydride and a specified monomer. CONSTITUTION:A polyisocyanate and optionally a photo-polymerization initiator are added to a resin having an ethylenically unsaturated group, obtained by reacting a rubber-like polymer having a hydroxyl, a prim. amino or a sec. amino with a cyclic acid anhydride and a monomer having an ethylenically unsaturated group and an epoxy or an aziridinyl.

Description

[Detailed Description of the Invention] [Object of the Invention] (Industrial Application Field) The present invention has adhesive properties during bonding, can temporarily adhere to adherends, and hardens upon light irradiation to provide strong adhesive force. The present invention relates to a photocurable pressure-sensitive adhesive composition suitable as a so-called pressure-sensitive adhesive.

(Prior art) Photocurable adhesives have traditionally been suitable as so-called adhesives, which have tackiness during bonding, can temporarily adhere to adherends, and exhibit strong adhesive strength when cured by light irradiation. As a composition, one in which a monoreactive oligomer or monomer is blended with an adhesive polymer is known (Japanese Patent Publication No. 53-3189).
8, JP-A-60-69178, JP-A-61
-64773 publication.

JP-A-61-83274, JP-A-61-1015
No. 82, JP-A-61-101583.

(See Japanese Patent Application Laid-Open No. 61-103908, etc.). However, since these compositions contain a 9-reactive oligomer or a 7-reactive oligomer, the cohesive force is reduced.

In some cases, sufficient adhesive strength cannot be obtained after curing, or it is necessary to mechanically temporarily fix the adhesive in order to obtain sufficient adhesive strength after curing. It is also known to use adhesive polymers imparted with reactivity by introducing unsaturated groups or functional groups (see JP-A No. 61-83272, etc.), but monoreactive oligomers and monomers are also known. was necessary, and a decrease in cohesive force was unavoidable.

On the other hand, reducing the amount of reactive oligomers and monomers added to improve adhesive properties, especially cohesion, before curing;
Curability becomes low and adhesive strength after curing decreases. As described above, a photocurable pressure-sensitive adhesive composition that has sufficient adhesion properties before curing, particularly both cohesive force and adhesive force after curing, has not been developed.

Therefore, according to the previous invention (Japanese Patent Application No. 63-17465),
Excellent adhesive properties before curing and adhesive strength after curing. We have developed a photocurable adhesive composition in which the polymer itself is curable, but this resin alone has somewhat poor cohesive strength, and there is a possibility that it may slip or peel when attached to areas that are subjected to large amounts of force before curing. was there.

(Problems to be Solved by the Invention) The present invention improves the above-mentioned problems of conventional photocurable adhesive compositions, namely, the drawback of poor cohesive force before curing, by partially crosslinking the resin with polyisocyanate. However, since the polymer itself is photocurable, the present invention provides a photocurable pressure-sensitive adhesive composition that has sufficient adhesive properties before curing and adhesive strength after curing.

[Structure of the invention]

(Means for Solving the Problems) The present invention provides a rubbery polymer (a) and a cyclic acid anhydride (b) having 9 hydroxyl groups and 9 primary or secondary amino groups.

and a resin (A) having an ethylenically unsaturated group in its side chain obtained by reacting a monomer (e) having an ethylenically unsaturated group with an epoxy group or an aziridinyl group, and this resin is added for partial crosslinking. polyisocyanate)
This is a photocurable adhesive composition comprising (B) and, if necessary, a photopolymerization initiator (C).

In the present invention, the rubbery polymer (a) having a hydroxyl group, a primary amino group or a secondary amino group includes a hydroxyl group,
In addition to acrylic resins having primary or secondary amino groups, saponified vinyl acetate polymers such as polyvinyl acetate, ethylene-vinyl acetate copolymer, and vinyl chloride-vinyl acetate copolymer can be used. .

The acrylic resin having a hydroxyl group, a primary amino group, or a secondary amino group is a homopolymer of a monomer having a hydroxyl group, a primary amino group, or a secondary amino group.

Copolymers of these monomers, alkyl (meth)acrylates, and vinyl acetate with these monomers.

These include copolymers with other monomers such as vinyl propionate, vinyl ether, and styrene (meth)acrylonitrile. Examples of the seven polymers having a hydroxyl group include 2-hydroxyethyl (meth)acrylate and 3-hydroxypropyl (meth)acrylate.

Examples include hydroxyalkyl (meth)acrylates such as 2-hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, and 2-hydroxybutyl (meth)acrylate, N-methylolacrylamide, and allyl alcohol.

Among these, 2) the reaction time to obtain the resin (A) is short; 2) the viscosity of the resulting pressure-sensitive adhesive composition is low; and 5) the pressure-sensitive adhesive composition does not ooze out when temporarily adhered to an adherend. Among the hydroxyalkyl (meth)acrylates, it is preferable to use hydroxyalkyl (meth)acrylates in which the alkyl has 2 to 4 carbon atoms. Preferably 3-4. Monomers having a primary amino group or a secondary amino group, which are particularly preferably used, include aminoethyl (meth)acrylate, N-methylaminoethyl (meth)acrylate, N-methylaminoethyl (meth)acrylate, N-methylaminoethyl (meth)acrylate,
-ethylaminoethyl (meth)acrylate and the like. Examples of alkyl (meth)acrylates include alkyl (meth)acrylates such as methyl (meth)acrylate, ethyl (meth)acrylate, butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, and octyl (meth)acrylate.

In the present invention, the cyclic acid anhydride (b) is an intramolecular anhydride of polycarboxylic acid, such as saturated or unsaturated aliphatic polycarboxylic acid anhydride, alicyclic polycarboxylic acid anhydride,
Aromatic polycarboxylic acid anhydrides, etc., or partially saturated or unsaturated hydrocarbon groups.

Some are substituted with aromatic ring groups, halogen atoms, heterocyclic groups, etc. Specific examples of these include succinic anhydride, phthalic anhydride, maleic anhydride, itaconic anhydride, glutaric anhydride, dodecenyl succinic anhydride, 5 Chlorendic anhydride, pyromellitic anhydride, trimellitic anhydride, cyclopenkune tetracarboxylic dianhydride, hexahydrophthalic anhydride, methylhexahydrophthalic anhydride, tetramethylene maleic anhydride, tetrahydrophthalic anhydride,
Methyltetrahydrophthalic anhydride, endomethylenetetrahydrophthalic anhydride, methylendomethylenetetrahydrophthalic anhydride M, 5-(2,5-dioxotetrahydroxyfuryl)-3-methyl-3-cyclohexene-
1,2-dicarboxylic anhydride, methylnadic anhydride,
Benzophenone tetracarboxylic anhydride, ethylene glycol bis(anhydrotrimellitate).

Examples include glycerol tris (anhydrotrimellitate). Among these, it is preferable to use dicarboxylic acid or tricarboxylic acid anhydrides that do not form a crosslinked structure.

In the present invention, the heptamer (C) having an ethylenically unsaturated group and an epoxy group or an aziridinyl group includes:
(7) 2-(1-aziridinyl)ethyl (meth)acrylate containing epoxy groups such as glycidyl (meth)acrylate, glycidyl cinnamate allyl glycidyl ether, vinylcyclohexane monoepoxide, 1,3-butadiene monoepoxide, etc. ), 2- (1-
aziridinyl)butyl(meth)acrylate), 2-(1
-aziridinyl)propyl(meth)acrylate, which have an aziridinyl group, and these may be substituted with a saturated or unsaturated hydrocarbon group, an aromatic ring group, a halogen atom, a heterocyclic group, etc.

The above rubbery polymer (a), cyclic acid anhydride (bl, and monomer (C) are reacted to obtain a resin (A) having an ethylenically unsaturated group in the side chain.The reaction is carried out in the presence of an appropriate solvent. or in the absence, N,N-dimethylbenzylamine, triethylamine, tributylamine.

Using tertiary amines such as N,N-diethylaniline and N,N-dimethylaniline as a catalyst, hydroquinone and hydroquinone 7-methyl ether are produced.

This can be carried out with the addition of a radical polymerization inhibitor such as tert-butylcatechol or p-benzoquinone. The hydroxyl group, primary amino group or secondary amino group of the rubbery polymer (a) and the acid anhydride group of the cyclic acid anhydride (b) first react preferentially, and then the carboxyl group produced by this reaction reacts with the acid anhydride group of the cyclic acid anhydride (b). The epoxy group or aziridinyl group of the monomer (C1) reacts to produce a secondary hydroxyl group or amino group.Furthermore, the resulting hydroxyl group or amino group reacts with the cyclic acid anhydride (the acid anhydride group of bl). Then, the same reaction as above can proceed in sequence, by adjusting the amount of cyclic acid anhydride (b) and monomer (C) to be reacted with respect to the amount of rubbery polymer (al). To the rubbery polymer (a).

Slightly longer side chains of desired length with a desired number of ethylenically unsaturated groups can be introduced. cyclic acid anhydride) is a dicarboxylic acid anhydride, the hydroxyl group, primary amino group and secondary amino group 1 of the rubbery polymer (a)
Also in proportions of 1 to 10 mol of cyclic acid anhydride (b) and 1 to 10 mol of monomer (C) per mole.

It is preferable that the cyclic acid anhydride (b) and the monomer (C) are reacted in approximately equimolar proportions. Cyclic acid anhydride (b)
is a tricarboxylic acid anhydride, the hydroxyl group, primary amino group and secondary amino group 1 of the rubbery polymer (a)
1 to 10 moles of cyclic acid anhydride (b) and 11 to 20 moles of cyclic acid anhydride (b), and approximately 1 to 10 moles of monomer (C) per mole of cyclic acid anhydride (b).
It is preferable to react at a ratio of 2 moles. Rubbery polymer (a cyclic acid anhydride (the amount of BL is 1
If the amount is less than 1 mole, the number of ethylenically unsaturated groups in the resulting resin (A) may decrease, making it impossible to impart sufficient reactivity to the resin (A), and if it exceeds 10 moles, unreacted The cyclic acid anhydride (b) and monomer (C1 remain) and are not bonded to the rubbery polymer (a).

There is a tendency for more reaction products to be produced between the cyclic acid anhydride (b) and the monomer (cl).
Because it has one or more, usually two or more, rather long side chains having at least nine ethylenically unsaturated groups.

The resin (A) itself has sufficient curability and exhibits sufficient adhesive strength after curing even without the use of monoreactive oligomers or monomers. Moreover, since it has an ethylenically unsaturated group in its side chain, the adhesive properties of the rubbery polymer (a) are maintained. Furthermore, in the present invention.

Examples of the polyisocyanate (B) for partially crosslinking the resin include tolylene diisocyanate, 4.4' diphenylmethane diisocyanate, hexamethylene diisocyanate, m-xylene diisocyanate, p-xylene diisocyanate, 1.5-naphthalene diisocyanate, isophorone diisocyanate, Dimeryl diisocyanate Diisocyanates such as lysine diisocyanate, hydrogenated 4,4'-diphenylmethane diisocyanate, hydrogenated tolylene diisocyanate, double-terminated isocyanate adducts of these with glycols or diamines, or mixtures thereof are necessary. Depending on the requirements, tri- or higher functional polyisocyanates such as triphenylmethane triisocyanate and polymethylene polyphenylisocyanate may also be used by mixing with these diisocyanates. The amount of polyisocyanate used varies depending on the amount of monomers having a hydroxyl group, primary amino group or secondary amino group in the rubbery polymer (a), and the amount of acid anhydride (b) and monomer (C) in the side chain. is used in a proportion of usually 0.1 to 10 parts by weight, preferably 0.3 to 5 parts by weight, based on 100 parts by weight of resin (A).

In this way, as a result of adding polyisocyanate and partially crosslinking the resin, the cohesive force becomes particularly strong, resulting in a well-balanced adhesive property before curing and adhesive force after curing.

In the present invention, as the photopolymerization initiator (C) used as necessary, benzoin, benzoin methyl ether, benzoin ethyl ether, methyl 0-benzoylbenzoate-p-benzoin ethyl ether, benzoin isopropyl ether, α-methyl Benzoins such as benzoin, acetophenones such as dimethylbenzyl ketal, trichloroacetophenone, 2,2-jethoxyacetophenone, and 2-hydroxy-2-methylpropiophenone.

Propiophenones such as 2-hydroxy-4'-isopropyl-2-methylpropiophenone, α-adyloxime ester, benzophenone, methylbenzophenone,
In addition to benzophenones such as p-chlorobenzophenone and p-dimethylaminobenzophenone, thioxanthone such as 2-chlorothioxanthone, 2-ethylthioxanthone, and 2-isopropylthioxanthone, benzyl, dibenzosuberone, etc., Kiyoshi Kato 1g: rUV- E
B Curing Handbook - Raw Materials & [-J (December 1985, Kobunshi Publishing Series) pp. 67-73 or Fuzo Yamashita,
“Crosslinking Agent Handbook” edited by Tosuke Kaneko (October 1982)
There is one described on pages 582 to 593 of May, published by Taiseisha). The photopolymerization initiator (C) may be used together with a photopolymerization accelerator. As such a photopolymerization accelerator.

4.4'-bis(diethylamino)benzophenone.

In addition to ethyl N-dimethylaminobenzoate, dimethylethanolamine, glycine, etc., those described in Kiyoshi Kato, ed., supra, pp. 67-73 can be used.

When using ultraviolet light as light, from the viewpoint of curing efficiency,
It is preferable to use a photopolymerization initiator (C) and, if necessary, a photopolymerization accelerator. The photopolymerization initiator (C) is a resin (
A) It is used in a proportion of usually 0.05 to 20 parts, preferably 0.5 to 10 parts per 100 parts by weight.

To further strengthen the adhesive strength after curing.

In the adhesive composition of the present invention, the resin (A) having an ethylenically unsaturated group in the side chain, polyisocyanate-1-(
B), in addition to the photopolymerization initiator (C) and the photopolymerization accelerator,
Furthermore, a monomer or oligomer having an ethylenically unsaturated group such as a (meth)acryloyl group can be added. Such monomers and oligomers include styrene, alkyl(meth)acrylates, (meth)acrylic acid, polyhydric alcohol poly(meth)acrylates, epoxy poly(meth)acrylates, oligoester poly(meth)acrylates, polyurethane poly(meth)acrylates, ) In addition to acrylate, diallyl phthalate, diallyl isophthalate, etc., low-molecular compounds having a hydroxyl group, primary amino group or secondary amino group, cyclic acid anhydrides, and monomers having an ethylenically unsaturated group and an epoxy group or an aziridinyl group An unsaturated oligoester or an unsaturated oligoamide obtained by reacting can be used. What are the amounts of these monomers and oligomers used?

It is 60 weight percent or less based on the total solid content of the adhesive composition of the present invention. If it exceeds 60% by weight, the adhesive properties before curing,
In particular, the cohesive force becomes significantly inferior.

The pressure-sensitive adhesive composition of the present invention may optionally contain pigments, dyes, and inorganic fillers within a range that does not impair its performance.

Organic solvents, metal powders such as silver powder, copper powder, nickel powder, etc.

Carbon black, a tackifier such as graphite xylene resin or rosin resin, a silane coupling agent, etc. can be added.

The pressure-sensitive adhesive composition of the present invention can be applied to paper or cloth treated with silicone, paper or cloth treated with a low-adhesion resin such as polyethylene terephthalate film laminated paper, metal foil, plastic film, etc. with high releasability. Coat it on a film, sheet, tape, etc., remove the organic solvent by drying if necessary, and cut it if necessary.
In the form of double-sided or single-sided adhesive sheets or tapes. In addition, for reinforcement and impact mitigation, it may be lined with a non-woven fabric such as rayon or nylon or a fabric such as cheesecloth, or these fabrics may be used as a core material by impregnating them with the adhesive composition of the present invention. You can also do it.

The thus obtained double-sided adhesive sheet or tape is sandwiched between two adherends of the same type or different types, at least one of which is light-transmissive, and after temporary adhesion due to its good adhesive properties, it is irradiated with light. By doing so, the adhesive composition is cured, and the adherends can be firmly adhered to each other. In addition, single-sided adhesive sheets or tapes can be temporarily attached to adherends due to their good adhesive properties, and then, if necessary, the base sheet or tape can be peeled off and the resulting adhesive surface can be used to attach other adherends. The adhesive composition is further temporarily adhered and irradiated with light to cure the adhesive composition, thereby making it possible to firmly adhere the adhesive composition to the adherend.

In the present invention, light includes visible light from the sun or fluorescent lamps, ultraviolet rays from high-pressure mercury lamps, ultra-high-pressure mercury lamps, metal halide lamps, carbon arc lamps, xenon lamps, etc., and electron beam accelerators as radiation sources. electron beam CO
These are gamma rays whose source is 6°, or X-rays whose source is an X-ray generator. Among these, visible light,
Ultraviolet light or electron beam.

In particular, it is preferable to use visible light or ultraviolet light having a wavelength of 200 to 800 nm. When using ultraviolet rays as light, the same applies from the viewpoint of curing efficiency.

It is preferable to use a photopolymerization initiator (C) and, if necessary, a photopolymerization accelerator. power of the source, distance from the source,
Although it varies depending on the irradiation area, the type and amount of the resin used, the photopolymerization initiator and photopolymerization accelerator, the thickness of the adhesive composition layer, etc., the time of light irradiation is usually about 0.3 seconds or more.

(Examples) The present invention will be explained below with reference to Examples. In the examples, 2 parts represents parts by weight.

Example 1 Butyl acrylate 88 parts Vinyl acetate 5.6 parts 2-
Hydroxyethyl methacrylate 6.2 parts Azobisisobutyronitrile 0.15 parts Ethyl acetate 122.3 parts To 111 parts of the mixture having the above composition heated to 80°C.

After dropping 9 drops of 111 parts of the mixture having the above composition.

Heat under reflux for 12 hours, cool, and add hydroquinone to 0°0
5 parts were added to obtain a solvent solution (solid content: 45% by weight) of a rubbery polymer having hydroxyl groups.

Solvent solution 18 of the obtained rubbery polymer having hydroxyl groups
4 parts, hexahydrophthalic anhydride 9 parts, glycidyl methacrylate 8 parts, N,N-dimethylbenzylamine 0
．． 5 parts and 0.2 parts of hydroquinone were mixed and heated to 80°C.
After reacting for 12 hours, 35 parts of ethyl acetate was added to obtain a solvent solution (solid content: 40% by weight) of a resin having an ethylenically unsaturated group in a slightly long side chain.

100 parts of a solvent solution of the obtained resin having an ethylenically unsaturated group in a slightly long side chain, and 0.0 parts of tolylene diisocyanate.
4 parts and 0.4 parts of 2-hydroxy-2-methylpropiophenone were uniformly mixed and coated onto a silicone-treated polyethylene terephthalate film to a dry thickness of 30 μm.

It was dried at 60° C. for 3 minutes to obtain a pressure-sensitive adhesive sheet.

Regarding the obtained adhesive sheet, the peel adhesion strength before photocuring,
The results of measuring the holding force and shear adhesive strength after photocuring are shown in the table.The measurements were carried out as follows.

■Peel adhesion strength before photocuring A polyethylene terephthalate sheet with a thickness of 50 μm is pasted on the adhesive surface of the obtained adhesive sheet, cut into 25 mm width pieces, the polyethylene terephthalate film is first peeled off, and the resulting adhesive surface is covered with paper. It was attached to a stainless steel plate (SUS304) polished with a #280 file, left for 30 minutes, and then the 180° peel adhesive strength was measured at a peel rate of 300 mm/min at 25° C. and 65% relative humidity.

■ Holding power before photocuring A polyethylene terephthalate sheet with a thickness of 50 μm was attached to the adhesive surface of the obtained adhesive sheet, and the length was 251 cm and the length was 1
The polyethylene terephthalate film was first peeled off, and a portion of the resulting adhesive surface, measuring 25 mm in length and 25 nm in width, was attached to a stainless steel plate (SUS304) polished with sandpaper #280. The time (seconds) required for the adhesive sheet to fall from the stainless steel plate was measured at 40° C. and under a load of 1 kg.

■ Shear adhesive strength after photocuring: 150 mm, width 10 mm, thickness 1.5 mm.
The adhesive side of each piece cut into 10 mm width pieces was pasted on, and the polyethylene terephthalate film was peeled off.

The two parts were pasted so that the adhesive surfaces overlapped, and the adhesive was cured by irradiating ultraviolet rays for 15 seconds under a high-pressure mercury lamp at a distance of 15 cm.Then, the adhesive was cured at 25°C and 65% relative humidity. The shear strength was measured at a tensile rate of 5 ms+/min. Those with a shear strength of 25 kg/cIi or more were considered to be passed.

Example 2 Butyl acrylate 89 parts Vinyl acetate 5.6 parts 2-
Hydroxyethyl acrylate) 5.6 parts Azobisisobutyronitrile 0.15 parts Ethyl acetate 233 parts To 167 parts of the mixture having the above composition heated to 80°C.

After dropping 167 parts of the mixture having the above composition and completing one drop.

Heat under reflux for 12 hours, cool, and add hydroquinone to 0°0
5 parts were added to obtain a solvent solution (solid content: 30% by weight) of a rubbery polymer having hydroxyl groups.

Solvent solution 17 of the obtained rubbery polymer having hydroxyl groups
9 parts of hexahydrophthalic anhydride, 22 parts of glycidyl methacrylate, 0.5 part of N,N-dimethylbenzylamine and 0.3 part of hydroquinone,
After reacting at 0° C. for 12 hours, 25 parts of ethyl acetate was added to obtain a solvent solution (solid content: 40% by weight) of a resin having an ethylenically unsaturated group in a slightly long side chain.

The obtained cutting solution of the resin having an ethylenically unsaturated group in a slightly long side chain was mixed with 0.00% of tolylene diisocyanate.
4 parts and 0.4 parts of 2-hydroxy-2-methylpropiophenone were uniformly mixed to obtain a pressure-sensitive adhesive sheet in the same manner as in Example 1, and the results of measurement are shown in the table.

Example 3 233 parts of a solvent solution of the rubbery polymer having hydroxyl groups obtained in Example 2, 16 parts of hexahydrophthalic anhydride
parts, 14 parts of glycidyl methacrylate.

After mixing 0.5 parts of N,N-dimethylbenzylamine and 0.3 parts of hydroquinone and reacting at 80'C for 12 hours, 70 parts of ethyl acetate was added to add an ethylenically unsaturated group to the slightly long side chain. Solvent solution of resin (solid content 30
% by weight) was obtained.

100 parts of a solvent solution of the obtained resin having an ethylenically unsaturated group in a slightly long side chain, and 0.0 parts of tolylene diisocyanate.
3 parts and 0.3 parts of 2-hydroxy-2-methylpropiophenone were uniformly mixed to obtain a pressure-sensitive adhesive sheet in the same manner as in Example 1, and the measurement results are shown in the table.

Comparative Example The measurement results obtained when tolylene diisocyanate was not added in Example 1 are shown in Comparative Example 1. The measurement results obtained when tolylene diisocyanate was not added in Example 2 are shown in the table as Comparative Example 2.

〔Effect of the invention〕

In the adhesive composition of the present invention, the polymer itself has photocurability, and as shown in Table 1, the adhesive composition before curing has a peel adhesive strength of 1500.
g/25mm or more, the holding force measurement results showed no deviation even after 24 hours, and the shear adhesive strength after curing was 25kg/c.
m'' or more is excellent, and the holding power is significantly improved compared to the one without the addition of polyisocyanate.

In this way, the present invention has high adhesiveness and can be temporarily bonded to the adherend during bonding.2 Mechanical temporary fixing is unnecessary, and after curing, it exhibits strong adhesive strength and has adhesive properties before curing. In particular, it has become possible to obtain a photocurable pressure-sensitive adhesive composition with an excellent balance between cohesive force and adhesive force after curing.

Claims (1)

[Claims] 1. Reacting a rubbery polymer (a) having a hydroxyl group, a primary amino group, or a secondary amino group, a cyclic acid anhydride (b), and a monomer (c) having an ethylenically unsaturated group and an epoxy group or an aziridinyl group. A photocurable pressure-sensitive adhesive composition comprising a resin (A) having an ethylenically unsaturated group in its side chain, a polyisocyanate (B), and, if necessary, a photopolymerization initiator (C).