JPS6183274A - Photo-curing self-adhesive molding - Google Patents

Abstract

PURPOSE:To provide a photo-curing self-adhesive in sheet form consisting of a low-molecular weight copolymer with a reactive group, a crosslinking agent, a photo-polymerizing compd. and a photosensitizer, exhibiting excellent initial adhesion and developing sufficient bonding power upon photo-curing. CONSTITUTION:The adhesive is a resin compsn. comprising (A) 100pts.wt. copolymer consisting of (a) about 1-30wt% unsatd. monomer with active hydrogen [e.g. (meth)acrylic acid] and (b) about 99-70wt% unsatd. monomer copolymerizable with (a) [e.g. alkyl (meth)acrylate having a 1-12C alkyl group] and having an average M.W. of 3,000-5,000, (B) about 0.1-15pts.wt. crosslinking agent (e.g. tolylene diisocyanate), (C) (meth)acryloyl group-contg. photopolymerizing compd. used in about 10-80wt% of (A)+(C) and (D) photosensitizer used in about 0.05-20wt% of (A)+(C). The compsn. is formed into sheet of about 100-600mu thick.

Description

[Detailed Description of the Invention] [Industrial Application Field] This invention has adhesive properties at the time of bonding and can be temporarily bonded to various adherends, and also cures by light irradiation to exhibit sufficient adhesive strength. The present invention relates to a photocurable pressure-sensitive adhesive molded product 6 in the form of a film or sheet.

[Conventional technology]

BACKGROUND ART Conventionally, solvent-containing adhesives, emulsion-type adhesives, and moisture-hardening monomer-type adhesives such as cyanoacrylate 1- are known as liquid adhesives used for bonding various adherends. However, all of these
It takes time to volatilize and there are problems with the working environment.
Furthermore, since it is in liquid form, it is difficult to handle and has poor workability.

In addition, there are adhesive tapes of thermosetting type, moisture-curing type, and hot-melt type to solve the above-mentioned problems, but these also have various demerit points. For example, thermosetting types require heating at high temperatures to harden, so they cannot be used on heat-sensitive plastics.
Another drawback is that it requires a considerable amount of heating time to fully cure.

Also, in the case of the moisture-curing type, it takes a long time to obtain sufficient curing, which poses a problem in terms of work efficiency. Furthermore, hot-melt type adhesives can be bonded in a fairly short process of melting, adhering, and cooling, but because they do not cure through chemical bonds such as crosslinking, they have the disadvantage that adhesive strength decreases when placed over hot water. In addition to being inferior in temperature-sensing characteristics, it has almost no adhesive strength until it melts, so temporary adhesion cannot be performed and there is a problem in that positioning workability with respect to adherends is poor.

On the other hand, in recent years, photocurable pressure-sensitive adhesives that can be cured in a short time at room temperature and are composed of a base polymer, a photopolymerizable compound (100%), and a photosensitizer have been developed to overcome the drawbacks mentioned above. is gaining attention.

However, this product has a problem in that it is actually difficult to balance the adhesive strength before light irradiation and the adhesive strength after light curing. In other words, if you try to increase the adhesive strength before light irradiation by increasing the amount of base polymer, the content of the photopolymerizable compound will decrease relatively, so the adhesive strength after light irradiation will decrease, and conversely, the adhesive strength after light irradiation will decrease. If the amount of polymer is reduced, even if good results are obtained in terms of adhesive strength after light irradiation, it becomes difficult to satisfy the adhesive strength before light irradiation.

[Problem that the invention seeks to solve]

This invention addresses the above-mentioned problems of conventional photocurable adhesives, which have various advantages over other adhesives such as thermosetting, moisture-curing, and hot-melt adhesives; The object of the present invention is to solve the problem that it is difficult to achieve both adhesion strength after irradiation and to obtain a photocurable pressure-sensitive adhesive molded product in the form of a film or sheet that has both of the above characteristics.

[Means for solving problems]

As a result of intensive studies to solve the above problems, the inventors used a relatively low molecular weight base polymer (oligomer) having a particularly crosslinkable group as a base polymer, and crosslinked it with a crosslinking agent. - When the polymer is used in a small amount, sufficient adhesive strength can be exerted by the crosslinking agent, and as a result, the amount of photopolymerizable compound can be relatively increased, so that the amount of photopolymerizable compound can be relatively increased. They found that it was possible to improve the adhesive strength after irradiation and completed this invention.

That is, the present invention provides a) a product having a weight average molecular weight of 3.00 obtained by copolymerizing an unsaturated monomer having active hydrogen that can contribute to crosslinking and an unsaturated monomer copolymerizable with this monomer;
0 to 50,000, b) a crosslinking agent that can react with the active hydrogen in this copolymer, and c) a light having at least one (meth)acryloyl group in one molecule. The present invention relates to a photocurable adhesive molded article formed by molding a photocurable adhesive composition containing a polymerizable compound and (d) a photosensitizer into a sheet, film, or the like.

[Structure and operation of the invention]

a in the photocurable adhesive composition used in this invention
Examples of unsaturated monomers having active hydrogen that can contribute to crosslinking used to obtain the components include carboxyl group-containing unsaturated monomers such as (meth)acrylic acid, maleic acid, fumaric acid, itaconic acid, and allyl acetic acid. , hydroxyethyl (meth)acrylate, hydroxypropyl (meth)acrylate, allyl alcohol, polyethylene glycol and (
Hydroxyl group-containing unsaturated monomers such as monoesters with meth)acrylic acid, monovinyl ethers of ethylene glycol or polyethylene glycol, monovinyl ethers of propylene glycol or polypropylene glycol, aminoethyl (meth)acrylate, N-methylaminoethyl (meth) ) acrylate, N-ethylaminoethyl (meth)acrylate, and other primary or secondary amino group-containing unsaturated monomers, and one or more of these may be used.

In addition, as the unsaturated monomer that can be copolymerized with the unsaturated monomer described in "2" having active hydrogen used to obtain component a, (meth)acrylic acid whose alkyl group has 1 to 12 carbon atoms is used. Alkyl esters are preferred, but other unsaturated monomers such as vinyl acetate, vinyl propionate, vinyl pyridine, (meth)acrylonitrile, (meth)acrylamide, diacetone acrylamide, and styrene may be mentioned, and one of these monomers may be used. Or use two or more types.

Component a can generally be obtained by copolymerizing 1 to 30% by weight of the unsaturated monomer having active hydrogen and 99 to 70% by weight of the unsaturated monomer copolymerizable therewith. The above copolymerization can be carried out using conventional radical initiators, such as organic peroxides such as benzoyl peroxide, methyl ethyl ketone peroxide, acetyl peroxide, lauroyl peroxide, and cumene hydroperoxide, and α・α゛-azobisiso Butyronitrile α・α′
- Using an azo initiator such as azobiscyanovaleric acid,
This may be carried out in the presence of a chain transfer agent such as thioglycolic acid, mercaptans such as 2-mercaptoethanol, or carbon tetrachloride.

The copolymerization is preferably carried out without using a solvent or diluent, that is, by bulk polymerization, but ordinary solution polymerization may also be used.

The low molecular weight copolymer as the C component obtained in this way has active hydrogen such as carboxyl groups, hydroxyl groups, and amino groups in the molecule, and has a weight average molecular weight of 3,000 to 3,000.
50,000, preferably in the range of 7,000 to 30,000. If the molecular weight is less than 3,000, the adhesive strength before irradiation with light will be poor, and if it exceeds 50,000, the viscosity of the composition will become too high, leading to problems such as poor molding workability.

Component b, that is, a crosslinking agent that can react with a functional group that can contribute to crosslinking of component C, is a crosslinking agent that reacts with component C to form a photocurable pressure-sensitive adhesive composition into a sheet shape. It is an important component to provide sufficient adhesive properties before curing.

Such crosslinking agents include tolylene-2,4-diisocyanate, tolylene-2,6-diisocyanate, diphenylmethane-4,4'-diisocyanate, naphthylene-1,5-diisocyanate, and combinations of trimethylolpropane and tolylene diisocyanate. 1:3 (mole ratio) adducts, isocyanate group-containing compounds such as reaction products of polyhydric alcohols such as polyethylene glycol or polypropylene glycol and tolylene diisocyanes 1-, neopentyl glycol diglycidyl ether, trimethylolpropane Polyglycidyl ether, epoxy group-containing compound such as bisphenol epoxy resin, trimethylolpropane tris(2-aziridinylpropionate), 1,1'-(4-methyl-m-
phenylene)-bis=3.3-aziridinyl urea, 1.
Examples include aziridinyl group-containing compounds such as 1'-(hexamethylene)-bis-3,3-aziridinyl urea and ethylenebis(2-aziridinylpropionate).
One or more of these may be used.

The amount of component b used is 0 with respect to 100 parts by weight of component C.
．． The amount ranges from 1 to 15 parts by weight, and if it is less than 0.1 parts by weight, the expected effect will not be obtained, and if it exceeds 15 parts by weight, the adhesive layer will become too hard and the adhesive properties will deteriorate.

Component C, that is, a photopolymerizable compound having at least one (meth)acryloyl group in the molecule, refers to a compound having at least one methacryloyl group or acryloyl group as a polymerizable double bond in the molecule, preferably two or more. For example, 1,4-butylene glycol (
meth)acrylate, 1,6-hexane gelicoldi(
Eastomer or epoxy acrylates such as meth)acrylate, neopentyl glycol di(meth)acrylate, polyprolene glycol di(meth)acrylate, trimethylolpropane tri(meth)acrylate, tetramethylolmethanetetra(meth)acrylate,
Examples include oligomers such as urethane-modified acrylate 1 and oligoester acrylate, and these may be used in combination with 2-seizure if necessary.

The blending ratio of C component is 10 in the total amount of C component and C component.
It is good to set it to ~80% by weight, preferably 30 to 70% by weight, and if the blending ratio of the C component in the amount of cuffs exceeds 80% by weight, the cohesiveness of the photocurable adhesive layer before light irradiation will deteriorate. This is undesirable because it causes adhesive to ooze out to the sides. Further, if it is less than 10% by weight, sufficient curing cannot be obtained, which is not preferable.

The photosensitizer for component C is not particularly limited as long as it promotes the photopolymerization reaction of component C.

For example, benzoins such as hengeine, hengeine methyl ether, hengeine ethyl ether, hengeine isopropyl ether, α-methylbenzoin, ■-
Examples include anthraquinones such as chloroanthraquinone and 2-chloroanthraquinone, hexphenones such as benzophenone, p-chlorohensiphenone, and p-dimethylaminohensiphenone, and sulfur-containing compounds such as diphenyl disulfide and tetramethylthiuram disulfide. Can be done.

The amount of component d used is preferably in the range of 0.05 to 20 parts by weight, preferably 0.5 to 10 parts by weight, based on 100 parts by weight of the total amount of component a and component C.

The photocurable adhesive composition used in this invention includes the above-mentioned a,
Components b, c, and d are essential components, and appropriate amounts of other compounding agents can be added depending on the purpose.

Examples of compounding agents include polymerization inhibitors that prevent thermal polymerization during production and reactions during storage, such as hydroquinone, hydroquinone methyl ether, tert-butylcatechol, p-benzoquinone, and 2,5-tert-butylhydroquinone. , phenothiazine, pigments such as zinc white, yellow lead, and hengara for the purpose of coloring or decoration, dyes such as toluidine ret, phthalocyanine blue, and phthalocyanine green, other metal powders, glass peas, glass powder, glass flakes, etc. Also included are tackifying resins such as xylene resins for the purpose of improving adhesive strength to the surface of adherends.

In this invention, the photocurable pressure-sensitive adhesive composition described in "2" is used and applied to a tape or sheet with high releasability such as low adhesive resin-treated paper or plastic film, or on other releasable surfaces. The photocurable pressure-sensitive adhesive composition of the present invention is generally molded into a tape or sheet having a thickness of 100 to 600 #m by casting and heating and drying. Note that this molded product may have a core material embedded therein, such as a nonwoven fabric such as a rayon nonwoven fabric or a nylon woven fabric, or a fabric such as cheesecloth, in order to provide reinforcement and buffering functions. Further, the tape or sheet having excellent releasability can be used as it is as a releasable support that is peeled off and separated from the molded product during use.

The photo-curing adhesive molded product of the present invention obtained by the above-described process can be interposed between, for example, two articles to be joined, at least one of which has a light-transmitting ability, and its good properties can be improved. After temporarily adhering both articles due to their adhesive properties, the above-mentioned articles having light transmittance are passed through a high-pressure water lamp, ultra-high pressure mercury lamp, metal halide lamp, carbon arc lamp,
Both articles can be firmly bonded by irradiating with light for 0.3 seconds or more, preferably 3 seconds or more using a light source such as a xenon lamp, and curing by photocrosslinking.

The product itself can be used as a double-sided tape or sheet, and the adhesive composition constituting it can be
By containing components c and d, it has good adhesiveness that can temporarily bond two articles to be joined, for example, and
It has an excellent adhesive force that allows both articles to be firmly bonded in a very short time by simply irradiating them with light after this temporary bonding.

〔Example〕

Next, examples of the present invention will be shown. In the following, "part" means part by weight, and "Mw" means weight average molecular weight.

Example 1 2-Ethylhexyl acrylate 60 parts Methyl methacrylate 35 parts 2-hydroxyethyl methacrylate 5 parts 2-Mekabutoethanol 3 parts 10 parts of the above blended composition and 0.2 part of Penpeil peroxide were placed in a flask. The mixture was stirred at 40°C for 30 minutes under a nitrogen atmosphere, then the temperature was raised to 80"C, and the remainder of the above blended composition was added dropwise over 2 hours. The temperature was then maintained at 80°C for an additional 2 hours to form a viscous copolymer. (Mw6,000) was obtained.

Next, to 50 parts of this copolymer, 5 parts of a reaction product of 3 moles of tolylene diisocyanate and 1 mole of trimethylolpropane, 50 parts of tetraethylene glycol dimethacrylate, 3 parts of benzophenone, and 0.005 parts of hydroquinone. parts were blended and mixed uniformly to prepare a photocurable pressure-sensitive adhesive composition.

This composition was coated on silicone-treated paper to a thickness of 5 mm after drying.
It was applied to a thickness of 0 μm and dried at 100° C. for 5 minutes to obtain a photocurable adhesive sheet.

Example 2 n-butyl acrylate 20 parts ethyl acrylate 80 parts methacrylic acid
10 parts lauryl mercaptan
A viscous copolymer (Mw 8,000) was obtained in the same manner as in Example 1 using 2 parts of the above blended composition and 0.2 parts of azobisisobutyronitrile.

Next, to 70 parts of this copolymer, 1 part of bisphenol type epoxy resin (Mw470), 0.2 parts of tributylamine, 30 parts of trimethylolpropane triacrylate, 3 parts of 1-hydroxycyclohexylphenyl ketone and 0.005 part of hydroquinone was blended and mixed uniformly to obtain a photocurable pressure-sensitive adhesive composition. A photocurable adhesive sheet was obtained using this composition in the same manner as in Example 1.

Example 3 Methyl itacrylate 25 parts Acrylonitrile 70 parts Methacrylic acid
5-part thioglycolic acid
A viscous copolymer (Mw 6,000) was obtained in the same manner as in Example 1 using 2 parts of the above-mentioned blended composition and 0.2 parts of "Zohisisobutyronitrile".

Next, to 60 parts of this copolymer, trimethylolpropane 1-lis(2-aziridinylpropionate)
5 parts, 40 parts of tetramethyloltetramethacrylate,
3 parts henzil dimethyl ketal and 0 hydroquinone
．． 005 parts were uniformly mixed to prepare a photocurable pressure-sensitive adhesive composition. A photocurable adhesive sheet was obtained using this composition in the same manner as in Example 1.

The results of characteristic tests conducted on each of the photocurable pressure-sensitive adhesive sheets obtained in each Example are shown in the table below.

The test method for each measurement item is as follows.

<Peel adhesion strength> A 60 μm thick polyvinyl chloride sheet was pasted on one adhesive surface of a photocurable adhesive sheet and cut into 20 mm width pieces.
The other adhesive side was attached to a BA-finished stainless steel plate 5US304 and left for 30 minutes, and then the adhesive strength of the polyvinyl chloride sheet was measured at 180 degrees at a peeling rate of 300 fi/min at 20°C and 65% R). (before light irradiation).

In addition, a high-pressure mercury lamp (80W/cm) was attached to a polyvinyl chloride sheet and a stainless steel plate in the same manner as above.
/ l light) from the back of the polyvinyl chloride sheet.
After irradiating ultraviolet rays for 5 seconds from a distance of m, the adhesive was left at 20° C. for 24 hours, and then peeled off at 180 degrees under the same conditions as described above to measure the adhesive strength (after irradiation).

<Tack> Stainless steel balls of different diameters are rolled on the adhesive surface of a photocurable adhesive sheet from a run-up distance of 10 cm at 20 °C and 65% RH on a slope with an inclination angle of 30 degrees, and stopped 10 cm from the adhesive surface. The ball depth of the largest ball (size - ball N [L x 1/36 inches)] is shown.

<Target adhesive strength> Cut the photocurable adhesive sheet into 201A layers x 201 sheets, paste acrylic plates with a thickness of 3 cranes on both sides, and heat the sheets at a distance of 10cn+ with a high-pressure mercury lamp (80W/cm/1 lamp). After irradiating with ultraviolet light for about 5 seconds, leave it at 20℃ for 24 hours,
Tensile shear force was measured at a pulling speed of 50 m+i/min at 65% RH.

- As is clear from Table 1, the photocurable adhesive molded product of the present invention has sufficient adhesiveness to temporarily bond two articles to be joined, and also firmly bonds both articles by light irradiation. It can be seen that it has excellent adhesive strength.

Claims (1)

[Claims] (1)a) A weight average molecular weight of 3,000 to 50, obtained by copolymerizing an unsaturated monomer having active hydrogen that can contribute to crosslinking and an unsaturated monomer copolymerizable with this monomer, 000
b) a crosslinking agent capable of reacting with the active hydrogen in the copolymer; c) a photopolymerizable compound having at least one (meth)acryloyl group in one molecule; d) A photocurable adhesive molded product obtained by molding a photocurable adhesive composition containing a photosensitizer into a sheet, film, or the like.