JPS6029754B2 - photosensitive adhesive - Google Patents

Description

[Detailed description of the invention] The present invention relates to photosensitive adhesives.

To be more specific, ■2-hydroxyalkyl acrylate (or methacrylate) and 3-methyl-△4-
Half-esterified product with tetrahydrophthalic anhydride, 'B}
The present invention relates to an alkaline water-soluble liquid photosensitive adhesive composition containing a water-repellent hydroxyalkyl acrylate (or methacrylate) and a photosensitizer as essential components. BACKGROUND OF THE INVENTION With recent improvements in photosensitive resin technology, photosensitive resins have come to be used for adhesion between two objects, at least one of which is transparent or semitransparent.

The advantage of using photosensitive resin as an adhesive is that it is a one-component type, so compared to a two-component type, there is less uniformity in the mixing process,
There is no need for troublesome defoaming or pot life, there is no need for a solvent evaporation process as volatile components can be eliminated, it is possible to bond objects that are impermeable to solvents, the curing time can be extremely shortened, and light It does not cure unless it is irradiated with irradiation, so there is no time limit for positioning objects to be adhered to, and since the viscosity can be varied over a wide range, it is possible to freely select the most suitable viscosity for the work. Because of these numerous advantages, photosensitive adhesives are now commercially available and are beginning to be put into practical use. However, a material with sufficient adhesive strength to glass and acrylic resin, which are the most important materials industrially for transparent or translucent objects, has not yet been obtained. Moreover, when bonding two objects together using a photosensitive adhesive, at least the bonded surface of one object is required to be completely bonded to the other object, rather than only partially. In this case, it is inevitable that an excess amount of the adhesive liquid will be squeezed out from the adhesive surface. In such cases, it is necessary to remove the protruding adhesive, but organic solvents are toxic and pose a fire hazard, and adhesives that can be removed with water have poor water and moisture resistance of the cured film. , alkaline water is preferred. Therefore, the photosensitive adhesive is required to have the property of being resistant to alkaline water but not to water. An adhesive that meets these conditions has not yet been developed. As a result of intensive research, we have developed an alkali-soluble photosensitive adhesion agent that has excellent adhesion to glass and acrylic resins. That is, the present invention provides {B} water-soluble hydroxyalkyl acrylate (or methacrylate) per 100 parts by weight of the half-J ester compound of 2-hydroxyalkyl acrylate (or methacrylate) and 3-methyl-△4-tetrahydrophthalic anhydride. )10
0 to 1 part by weight and 'q other polymerizable vinyl monomers and/or prepolymers with a boiling point of 100qo or higher 2
The present invention relates to a photosensitive adhesive containing as a main component 0.1 to 5 parts by weight of a photosensitizer per 10 parts by weight of a composition.

The characteristics of this photosensitive adhesive are 2-hydroxyalkyl acrylate (or methacrylate) and 3-methyl-△4-
It contains a half-esterified product with tetrahydrophthalic anhydride as an essential polymerization component. This half-esterified product has a high boiling point, no odor, and has high photopolymerizability.
The resulting polymer is strong, impact resistant, has excellent adhesion to glass and acrylic resin, has good water and green resistance, has a high refractive index and good transparency, and is resistant to water, but is resistant to alkaline water. It has many thorns and has the function of emulsifying and dispersing other water-insoluble monomers used in alkaline water together. Furthermore, despite its large molecular weight and carboxylic acid group, this hemiester has the great advantage of low viscosity. This half-esterified product is prepared, for example, in the presence of a known thermal polymerization inhibitor containing 2-hydroxyalkyl acrylate (or methacrylate) and 3-methyl-△4-tetrahydrophthalic anhydride at 80 to 120 oo in an air stream. It can be easily synthesized by heating for several hours. Examples of the 2-hydroxyalkyl acrylate (or methacrylate) used here include 2-hydroxyethyl acrylate (or methacrylate) and 2-hydroxybropylacrylate (or methacrylate). 3-methyl-△4
- Dibasic acid anhydrides other than tetrahydrophthalic anhydride (e.g. succinic anhydride, maleic acid, phthalic acid, tetrahydrophthalic anhydride, etc.) and half-esterified products of 2-hydroxyalkyl acrylate (or methacrylate) are also soluble in alkaline water. Although it is a monomer that does not dissolve in water, it may have poor adhesion to glass or acrylic resin, high viscosity, brittle cured products, and poor photopolymerizability.
Nothing comparable to the overall performance of the hemiesterified products described above is available.

Water-removable hydroxyalkyl acrylate (or methacrylate), which is the second essential polymerization component used in the present invention, can be used alone as a photosensitive adhesive for glass to some extent, but it has poor adhesion to acrylic resin, and the adhesive layer The water resistance of the material is extremely poor, but when used in combination with the above-mentioned essential component half-esterified material, the adhesion to both materials is significantly improved, assists in alkaline washability, and is a suitable material that does not impair the water resistance of the adhesive layer. It is a monomer. Water-based hydroxyacrylate (methacrylate) includes 2-hydroxyethyl acrylate (or methacrylate),
Examples include 2-hydroxypropyl acrylate (or methacrylate). The amount of this monomer should be kept within the range of 100 to 1 part by weight per 10 parts by weight of the hemi-esterified product; if it exceeds 100 parts by weight, water resistance will decrease, and if it is less than 1 part by weight, alkaline washing will be required. This is not preferable because it reduces performance. Examples of the polymerizable pinyl monomer and prepolymer having a boiling point of 100 oo or higher used in the photosensitive adhesive of the present invention include (meth)acrylic acid alkyl esters, (meth)acrylic acid, (meth)acrylic acid, and (meth)acrylic acid.
Examples include acrylic acid amides, vinyl esters, styrene and its derivatives, and allyl alcohol esters.

In addition, as prepolymers, (meth)acrylic esters of polyester polyols, (meth)acrylic esters of polyether polyols, adducts of polyepoxy compounds and (meth)acrylic acids, and polyols and hydroxyalkyl (meth)acrylates are used. A urethane compound bonded via a diisocyanate is used. These vinyl monomers and prepolymers do not necessarily have to be used together, but they can be used to add various properties to the adhesive (for example, adjusting the viscosity of the adhesive, imparting water repellency, improving the heat resistance of the cured film, and damaging objects to be adhered). It is also possible to use them together to provide properties such as providing anti-scattering properties and reducing the cost of adhesives. Furthermore, if the boiling point of the wing-forming vinyl monomer and prepolymer is less than 100 qo, it is not preferable because the evaporation loss is large, causing problems of air pollution and generating bad odors. The photosensitizer used in the present invention may be anything as long as it can initiate polymerization of the monomer and prepolymer when irradiated with actinic rays.

The active light is preferably a wavelength that is not strongly absorbed by glass or acrylic resin and that effectively excites the photosensitizer, and practically, light in the ultraviolet to visible range is desirable. Examples of sensitizers that meet these conditions include benzyl, diacetyl, benzophenone, benzoin, benzoin ether, and anthraquinone. Preferred light sources for curing the adhesives of the present invention include mercury lamps, ultraviolet fluorescent lamps, metal halide lamps, arc lamps, sunlight, and the like. The composition of the present invention may also include a known thermal polymerization inhibitor as an optional component to improve storage stability, a known dye or pigment for coloring, or a non-polymerization inhibitor that is compatible with the composition. The volume and viscosity may be increased using a polymeric filler material. The adhesive according to the present invention is particularly effective for bonding transparent or translucent glass plates or acrylic resins, and when bonding, the adhesive that protrudes from the object to be bonded is treated with alkaline water (inorganic or organic alkaline aqueous solution). It can be easily removed, and the performance of the photocured film after removal is also excellent.

Example 2-hydroxypropyl acrylate 130 and 3
-Methyl-Δ4-tetrahydrophthalic anhydride (166 kg) and hydroquinone (30 kg) were reacted for 2 hours at 120 Qo in an air stream to obtain a half-esterified monomer.

This monomer W. A photosensitive adhesive was prepared by mixing 5 parts of 2-hydroxyethyl methacrylate, 2 parts of vinyltoluene, and 1 part of penzoin ethyl ether. Pour 10 g of this adhesive into the center of a glass plate with a thickness of 5 mm and a diameter of 3 square meters, and then place an acrylic resin plate with a thickness of 3 mm and a diameter of 20 square meters on it, aligning the centers, and press it down at once. Place black paper that does not leave any light on the back of the glass plate, and cut out two melon antennae to fit the acrylic resin plate to allow light to pass through. When first irradiating the glass plate for 15 seconds with a Hina W ultra-high pressure mercury lamp from a distance of 30 arcs below the glass plate, the adhesive sandwiched between the two plates will harden, but the parts that protrude around the acrylic plate will remain uncured. It is in a state where it has started to gel a little. In this state, a 0.5% aqueous solution of caustic soda was sprayed to dissolve and remove the protruding portion, and the film was rinsed with water. After that, it was irradiated again with the same light source for 3 minutes to completely cure it. The bonded surfaces of the two plates bonded in this way are bubble-free, the entire surface of the acrylic plate is firmly bonded to the glass, and the glass surfaces around the outer 5 arcs are extremely clean, and the adhesive strength is strong and waterproof and moisture resistant. Heat resistance was also good.
Comparative Example When the same test was carried out by replacing the monomer ① in the example with 2-hydroxyethyl methacrylate, the protruding part could be washed with water, but the adhesive layer inside the 2nd side from the 4th circumference of the acrylic plate became cloudy with water. Peeling occurred.

Claims (1)

[Scope of Claims] 1 (A) Per 100 parts by weight of a half-esterified product of 2-hydroxyalkyl acrylate (or methacrylate) and 3-methyl-Δ^4-tetrahydrophthalic anhydride,
(B) A composition comprising 100 to 10 parts by weight of water-soluble hydroxyalkyl acrylate (or methacrylate), (C) 200 parts by weight or less of the following polymerizable vinyl monomer and/or prepolymer having a boiling point of 100°C or higher. A photosensitive adhesive whose main component is a photosensitizer added in an amount of 0.1 to 5 parts by weight per 100 parts by weight. Polymerizable vinyl monomers: (meth)acrylic acid alkyl esters, (meth)acrylic acid, (meth)acrylic acid amides, vinyl esters, styrene and its derivatives, allyl alcohol esters, polymerizable prepolymers: polyester (Meth)acrylic acid ester of polyol, (meth)acrylic acid ester of polyether polyol, adduct of polyepoxy compound and (meth)acrylic acid, bonding of polyol and hydroxyalkyl (meth)acrylate via diisocyanate modified urethane.