JPH0476364B2 - - Google Patents

Description

[Detailed description of the invention]

(a) Purpose of the invention [Field of industrial application] The present invention relates to a photocurable composition,
In particular, it relates to a photocurable composition that is rich in thixotropy and has excellent thickening properties. [Prior Art] A photocurable composition is a curable composition that easily polymerizes and cures when irradiated with light, and is used as a sealing agent for relay parts, an adhesive for fixing the end of a coil, or an adhesive for fixing a switch terminal, etc. , its use in electronic materials and light electrical fields is attracting attention. However, conventional photocurable compositions do not have thixotropy, or even if they do, have a low thixotropy coefficient, resulting in problems such as dripping, running, and stringing during application of photocurable compositions. occurred, causing various troubles. Some of the photocurable compositions having thixotropy contain silica, but their thixotropy coefficients are quite low and cannot be said to be practical. [Problems to be Solved by the Invention] The present inventors have worked diligently to obtain a photocurable composition that is rich in thixotropy, has excellent thickening properties, and solves problems such as dripping, running, and stringing during coating operations. As a result of research, the present invention was completed. (B) Structure of the invention [Means for solving the problems] The present invention provides a photocurable composition containing a urethane prepolymer [A] having a (meth)acryloyloxy group and a photopolymerization initiator [B]. This is a composition in which silica [C] treated with a silane compound having a chain hydrocarbon group having 6 or more carbon atoms is added as a thixotropic agent, and the composition is 0.1 per 100 parts by weight of component [A]. This is a thixotropic photocurable composition characterized by containing ~6 parts by weight of component [C]. In the present invention, (meth)acrylate or (meth)acryloyl collectively refers to acrylate and methacrylate, or acryloyl and methacryloyl. Component [A] in the present invention is a urethane prepolymer having a (meth)acryloyloxy group, and preferred specific examples include the urethane prepolymers shown below. A urethane prepolymer having a (meth)acryloyloxy group which is a reaction product of (meth)acrylate having a hydroxyl group and an organic polyisocyanate. Urethane prepolymer having a (meth)acryloyloxy group which is a reaction product A reaction product of a (meth)acrylate having a hydroxyl group, an organic polyisocyanate, a trivalent or higher polyol or a polyol consisting of a diol and a trivalent or higher polyol. Yes (meta)
Urethane prepolymer having an acryloyloxy group Among the raw materials for producing the urethane prepolymer having a (meth)acryloyloxy group in ~ above, specific examples of (meth)acrylate having a hydroxyl group include 2-hydroxyethyl (meth)acrylate, 3 -hydroxypropyl (meth)acrylate, hydroxybutyl (meth)acrylate, hydroxyhexyl (meth)acrylate, hydroxyoctyl (meth)acrylate and 2-hydroxy-3-chloropropyl (meth)acrylate. Specific examples of organic polyisocyanates that are other raw materials include tolylene diisyanate, 4,
4'-diphenyl diisocyanate, 4,4'-diphenylmethane diisocyanate, cyanidine isocyanate, 1,5-naphthalene diisocyanate, 4,4-diphenyl ether diisocyanate, p-phenyl diisocyanate, trimethylene diisocyanate, tetramethylene diisocyanate , hexamethylene diisocyanate,
Ethylene diisocyanate, cyclohexylene diisocyanate, nonamethylene diisocyanate,
Low molecular weight organic polyisocyanates such as octadecamethylene diisocyanate, 2-chloropropane diisocyanate, 2,2'-diethyl ether diisocyanate, tetrachlorophenylene diisocyanate, xylylene diisocyanate and 1,4,3-heptene diisocyanate; excess Amounts of these low molecular weight organic polyisocyanates can be added, as is already known, to primary amines, secondary amines or polyhydric alcohols such as glycerol, polyoxyethylene triol,
Obtained by adding ethylene oxide and/or propylene oxide to polyoxypropylene triol, polyoxyethylene tetraol, polyoxypropylene tetraol, polypropylene glycol, polyethylene glycol, polycaprolactone polyol, polytetramethylene ether glycol, bisphenol A Examples include high molecular weight organic polyisocyanates obtained by reacting with polyhydric alcohols such as ether type glycols. Further, some specific examples of polyols that are other raw materials include: diols include polyoxyethylene diol, polyoxypropylene diol, polyoxybutylene diol, polycalactone diol, hexane diol, and 1,4-
There are butanediol, hydrogenated bisphenol A, ethylene oxide adduct of hydrogenated bisphenol A, propylene oxide adduct of hydrogenated bisphenol A, ethylene oxide and propylene oxide random adduct of hydrogenated bisphenol A, etc. Examples of trivalent or higher polyols include trimethylolethane, trimethylolpropane, pentaerythritol, polyoxyethylene triol, polyoxypropylene triol, trishydroethyl isocyanurate, polyoxyethylene tetraol, polyoxypropylene tetraol, glycerin, and polyphosphoric acid. etc. All of the above monomers are preferably pure products, but may be of industrial grade containing trace amounts of inhibitors, stabilizers, etc. Moreover, the above-mentioned urethane prepolymers having (meth)acryloyloxy groups may be used alone or in combination. Examples of the photopolymerization initiator used in the present invention include benzyl, benzophenone, mirahiz ketone, 2-chlorothioxanthone, 2,4-diethylthioxanthone, 3,3',4,4'-tetra(t
-butylperoxycarbonyl)benzophenone, benzoin ethyl ether, diethoxyacetophenone, 4,4'-dichlorobenzophenone,
Examples include methyl o-benzoylbenzoate, benzyl dimethyl ketal, 2-hydroxy-2-methylpropiophenone, 4-isopropyl-2-hydroxy-2-methylpropiophenone, and 1-hydroxycyclohexyl phenyl ketone. In addition, a photopolymerization initiator having excellent absorption characteristics in the visible light region may be added. The proportion of the photopolymerization initiator is preferably 0.01 to 20 parts by weight, more preferably 0.1 to 10 parts by weight, per 100 parts by weight of component [A]. The silica of the present invention treated with a silane compound having a chain hydrocarbon group having 6 or more carbon atoms (hereinafter referred to as hydrophobic silica) means that the surface of the silica is
It is silica that has been hydrophobicized by treatment with the above-mentioned silane compound having a chain hydrocarbon group. Preferred specific examples of the silane compound having a chain hydrocarbon group having 6 or more carbon atoms include hexyltrimethoxy Silane, alkoxysilane derivatives such as octyltrimethoxysilane, lauryltriethoxysilane, stearyltrimethoxysilane,
Examples include halogen derivatives such as stearylmethyldichlorosilane. The particle size of the hydrophobic silica is preferably 100 mμ or less, more preferably 0.1 to 50 mμ.
It is. If it exceeds 100 mμ, layer separation may occur in the composition, so it cannot be said to be preferable. The blending ratio of hydrophobic silica is 100% of component [A].
0.1 to 6 parts by weight, preferably 0.5 to 5 parts by weight
Parts by weight. If it is less than 0.1 part by weight, no effect can be expected, and if it exceeds 6 parts by weight, no further effect can be expected. In addition to the above-mentioned components, various substances may be added to the composition of the present invention for various purposes. For example, in order to obtain storage stability, a radical polymerization inhibitor may be added, and specific examples of the radical polymerization inhibitor include quinones such as hydroquinone and hydroquinone monomethyl ether, phenothiazine, dinitrosoresorcinol, and oxalic acid. Further, dyes or pigments may be added for the purpose of coloring, or plasticizers may be added for imparting flexibility. The composition of the present invention can be easily prepared by mixing and dissolving the above-mentioned components at room temperature or under heating. As the curing means for the composition of the present invention, the curing means normally used for photocurable compositions, such as ultraviolet rays and visible light, are used. [Reference Examples, Examples, and Comparative Examples] The present invention will be described in more detail below using Reference Examples, Examples, and Comparative Examples. Note that all parts in each example represent parts by weight. Reference example: Charge approximately 41 parts of trirediisocyanate (hereinafter abbreviated as TDI) to a reactor, and while maintaining the reaction temperature at 80°C, gradually add approximately 28 parts of liquid hydrogenated bisphenol A at 150°C with stirring. is. After the preparation is complete, stir at 80℃ for about 1 hour, then lower the temperature to 80℃.
While maintaining the temperature at °C, about 31 parts of 2-hydroxyethyl methacrylate was gradually added with stirring, and stirring was continued until the disappearance of the NCO peak (near 2360 cm ^-1 ) was confirmed in the IR spectrum. Further, appropriate amounts of dibutyl Sn dilaurate as a catalyst and hydroquinone monomethyl ether as a polymerization inhibitor were added depending on the progress of the reaction. A solid methacrylic oligomer at room temperature was obtained by the above method. Examples 1 to 4 and Comparative Examples 1 to 6 Methacrylic oligomers obtained in Reference Examples or
NK Ester 4G (Product name: Shin-Nakamura Chemical Industry Co., Ltd.);
Polyethylene glycol dimethacrylate) and other components listed in Tables 1 and 2 were mixed to prepare Examples 1 to 6 and Comparative Examples 1 to 4. Regarding the curable compositions of Examples and Comparative Examples,
Properties and performance were measured as follows. The results are shown in Table 3. (1) Instrument used for viscosity measurement; Precision Equipment Research Institute Bismetron VG-
A1, Single cylindrical rotational viscometer measurement method; Rotor No.: See Table 3 Rotation speed: 6 rpm Measurement temperature: 25℃ (2) Instrument using thixotropic coefficient; Calculation of coefficient according to viscosity measurement in (1); Rotation (3) Photocuring time determined by the ratio of viscosity measured at several 6 rpm and 60 rpm.
4000 High pressure mercury lamp UVL-4000 (4kw 1 lamp)
Lamp output 80W/cm, semi-concentrating lamp irradiation distance: 15cm Measurement method: 25mm diameter on a propylene sheet,
An aluminum ring with a depth of 1 mm was placed, the prepared product was placed in it, and light was irradiated under the above conditions, and the time required until the surface became tacky when touched with a finger was defined as the photocuring time.

【table】

【table】

【table】

[Table] (C) Effects of the Invention The composition of the present invention is obtained by adding silica treated with a silane compound having a chain hydrocarbon group having 6 or more carbon atoms as a thixotropic agent to a conventional photocurable composition. It is a composition that is rich in thixotropy and has excellent thickening properties, and it eliminates the problems that conventional photocurable compositions suffer from, such as dripping, running, and stringing during application, and the defective rate of applied parts caused by this. Solving problems such as sealant for relay parts,
Adhesive for fixing coil ends or switch terminals,
This is a thixotropic photocurable composition that can greatly increase the productivity and reliability of parts to which it is applied, such as potting of electronic material-related parts.

Claims (1)

[Scope of Claims] 1. A photocurable composition containing a urethane prepolymer [A] having a (meth)acryloyloxy group and a photopolymerization initiator [B], further containing a thixotropic agent having 6 carbon atoms. Silica [C] treated with a silane compound having the above chain hydrocarbon group
It is a composition formed by adding 100% of component [A].
A thixotropic photocurable composition containing 0.1 to 6 parts by weight of component [C] per part by weight.