ACTINIC RADIATION-CURABLE COMPOSITION FOR CAST POLYMERIZATION AND PRODUCT OF CAST POLYMERIZATION

Abstract: This improved atinic radiation-curable compsn. for cast polymerisation comprises (A) 40 to 90 pts. wt. of a urethane poly(meth)acrylate, (B) 10 to 60 pts. wt. of a vinyl monomer, and (C) at least one of the cpds., methyl phenylglyoxylate; 2-hydroxy-2-methyl- 1-phenylpropan-1-one; hydroxycyclohexyl phenyl ketone; a photoinitiator represented by general formula (I), where R1 and R2 independently represent a phenyl, a methyl, an ethoxy, or an isopropyloxy gp. (A) is specified to have two or more (meth)acryloxy gps. per molecule. (B) is specified to have a boiling pt. of 100 deg.C or higher and it should be capable of undergoing radical polymerisation. The amt. of (C) is specified to be 0.005 to 5 pts. wt. per 100 pts. wt. of the sum of components (A) and (B). (B) is at least one monomer of formula (II) and/or (III), where R3, R4, R6 and R7 independently are H, CH3; R5 are a phenyl, a biphenyl, a cyclohexyl, a dicyclopentadienyl or an adamantyl gp.; m and n are independently one of the integers 0, 1, 2 or 3; p is an integer in the range 0-5; R8 is gp.(i) or (ii) where X is H, Cl or Br; R9 is H or CH3; 1 is an integer between 0 and 5. (C) is pref. 2,4,6-trimethylbenzoyl diphenylphosphinoxide. The cast polymerisation product made from this compsn. is produced by radical polymerisation fo the compsn. using actinic radiation.

Description: The present invention relates to an actinic ray curable composition for casting polymerization and to cast molded products obtained by radiation polymerising the aforementioned composition. Hitherto, actinic ray curable compositions comprising an oligomer (prepolymer) having (meth)acrylate terminal, a reactive monomer and a photopolymerization initiator have been widely used in the fields of paints, inks, coatings, electric materials, image formation, etc. because of the advantages that they cure in a short time at room temperature without using solvents which are harmful to the human bodies. The oligomer which is a main component of these photo-curable compositions includes representatively urethane (meth)acrylate, epoxy (meth)acrylate and polyester (meth)acrylate. Especially, urethane (meth)acrylate is noticed as paints and coating materials because of its superior impact resistance, heat resistance and ductility. For example, US-PS 3 907 865 discloses to cure urethane (meth)acrylate obtained using xylylene diisocyanate with active energy ray to form a film of a thickness up to 5 mm, preferably up to several hundreds µm. However, these films only useful for preparation of printing plates or reliefs. This is due to the fact that the irradiated light is absorbed and scattered by photo-polymerization initiators, powder etc., thereby preventing the light from reaching inside. According to JP-A 61-21 121 a composition having a low glass transition temperature is produced by compounding an urethane acrylate having (meth)acryloyl groups at both terminals and a monofunctional acrylate showing an intramolecular ether-bonding in the alcoholic component of the acrylate. The composition produced in the aforementioned way is used as a coating material for an optical fiber core. US-PS 3 553 174 describes a process for forming transparent and abrasion resistant articles which are obtained by step-growth polymerization of an aliphatic isocyanate compound and a hydroxyacrylate compound while concurrently carrying out chain-growth polymerization of the hydroxyacrylate compound. US-PS 4 443 588 describes a method for producing highly refractive urethane polymers for use in optical lenses. These polymers are produced by radical polymerization of a reaction product of a xylylene diisocyanate with a hydroxyl-group containing unsaturated compound. JP-A 61-278 521 discloses a photocurable resin composition giving a cured product like a photoresist. The resin composition comprises an urethane (meth)acrylate and a photopolymerization initiator, said urethane being formed by reaction of an organic diisocyanate with a polyalcohol and a (meth)acrylic ester derivative. JP-A 60 163 911 discloses a photocurable rubbery elastic composition which is formed by mixing a photoreactive urethane-acrylate prepolymer with a reactive diluent like an acrylic ester derivative in the presence of a sensitizer. However, the known photocurable compositions are either not curable to a deep portion of several mm up to several cm or require a long time for polymerization and, therefore, the productivity is very low. Furthermore, due to the use of heat catalysts like azoisobutyronitrile, benzoyl peroxide etc. the resulting products show yellowing, optical and stress strain, if they are used for optical and electrical uses. In addition, in case of optical materials epecially lenses for glasses a high refractive index of the same level as of ordinary inorganic glasses is desired. Therefore, it is an object of the present invention to provide an actinic ray curable composition for casting polymerization which is curable to a deep portion of several mm up to several cm, requires a short time for polymerization leading to an improved productivity, shows no yellowing or optical and stress strain and, if it is used for optical and electrical materials, shows a high refractive index of the same level as ordinary inorganic glasses. According to the invention this object is achieved by an actinic ray curable composition for casting polymerization showing the features given in claim 1 and the cast polymerization products according to claim 11. The invention is advantageously developed by the measures mentioned in the subclaims. The urethane poly(meth)acrylate (A) used in the present invention having at least two (meth)acryloyl groups in one molecule is a main component of the casting polymerization composition of the present invention and imparts good impact resistance, heat resistance, yellowing resistance and dyeability to the resulting molded products. It is produced by addition reaction of a polyisocyanate compound and a hydroxyl group-containing (meth)acrylate. The polyisocyanates used in the present invention are those represented by the general formula (IV) which are less in yellowing. (wherein Ar denotes phenylene, biphenylene, naphthylene or methane-bisphenylene). Among them, especially preferred are m-tetramethylxylene diisocyanate and p-tetramethylxylene diisocyanate. As typical examples of the hydroxyl group-containing (meth)acrylates, mentioned may be made of 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, addition reaction products of monoepoxy compounds such as butylglycidyl ether, 2-ethylhexylglycidyl ether, phenylglycidyl ether, glycidyl methacrylate and the like with (meth)acrylic acid, (meth)acrylic acid monoesters of polyethylene glycol or polypropylene glycol, etc. Urethanation reaction of said hydroxyl group-containing (meth)acrylates and said isocyanates can be prepared by known method, for example, by dropwise addition of a mixture of the hydroxyl group-containing (meth)acrylate and a catalyst, e.g., dibutyl tin dilaurate in the presence of the isocyanate compound at 50-90°C. As performances required for casting molded products, impact resistance is important, but, in some case, sufficient impact resistance cannot be obtained when using the above mentioned urethane (meth)acrylate (A). This is due to the molecular structure which constitutes the urethane (meth)acrylate. In order to improve impact resistance, it is preferred to introduce soft structures such as ethylene glycol portion and propylene glycol portion into molecular structure, but when contents of recurring units of ethylene oxide and propylene oxide are more than 5 mol %, not only the hardness of molded product decreases, but also refractive index decreases. For improvement of these defects, it is preferably to introduce simultaneosuly soft portion and rigid portion into molecule. Specifically, it is considered to introduce bisphenol A skeleton, bisphenol S skeleton and bisphenol F skeleton. Further, molecular weight is also important as a factor for improvement of impact resistance and this is improved with increase in molecular weight. In view of these facts, we have found that casting molded products superior in both the impact resistance and the heat resistance can be obtained by synthesis of urethane oligomers containing soft portion and rigid portion in the molecule which are represented by the formula (V). (wherein R₁₀, R₁₁ and R₁₂ each denotes a hydrogen atom or a methyl group, r and s each denotes an integer of 1 - 5, R₁₃ denotes and Y denotes polyisocyanate.). Urethane oligomers represented by the formula (V) can be synthesized by reacting the above polyisocyanate compound and hydroxyl group-containing (meth)acrylate at 1 : 1 and then reacting the reaction product with a diol of ethylene oxide or propylene oxide adduct of bisphenol A, a diol of ethylene oxide or propylene oxide adduct of bisphenol S or a diol of ethylene oxide or propylene oxide adduct of bisphenol F. As those which improve both the heat resistance and the impact resistance, bisdiethylenoxy diol adduct of bisphenol S and bisdipropyloxy diol adduct of bisphenol A are suitable. The radical polymerizable vinyl monomer (B) having a boiling point of at least 100°C which is the second component in the present invention serves as a reactive diluent for urethane oligomer (A) containing (meth)acryloyl group in the molecule. The casting polymerization composition desirably have a resin viscosity not exceeding 3-5 Pa·s (3000 to 5000 cps) as the range where the compositions can be poured into a mold. However, in case of photo-curable compositions, it is possible to heat them to the acceptable range of temperature, for example, to about 100°C, thereby reducing the viscosity. In this case, the resin viscosity may exceed the above range at room temperature. The radical polymerizable vinyl monomer (B) having a boiling point of 100°C or higher is not critical and may be optionally chosen depending on the object. As examples thereof, mention may be made of mono(meth)acrylic compounds such as methyl methacrylate, ethyl (meth)acrylate, n-butyl (meth)acrylate, i-butyl (meth)acrylate, t-butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, lauryl (meth)acrylate, stearyl (meth)acrylate, cyclohexyl (meth)acrylate, benzyl (meth)acrylate, phenyl (meth)acrylate, phenoxyethyl (meth)acrylate, phenoxypropyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, glycidyl (meth)acrylate, tetrahydrofurfuryl (meth)acrylate, phenylglycidyl (meth)acrylate, dimethylaminoethyl (meth)acrylate, phenylcellosolve (meth)acrylate, N-vinyl-2-pyrrolidone (meth)acrylate, dicyclopentenyl (meth)acrylate, biphenyl (meth)acrylate, 2-hydroxyethyl(meth)acryloyl phosphate and the like, vinyl compounds such as styrene, vinyltoluene, chlorostyrene, divinylbenzene, 1-vinylnaphthalene, 2-vinylnaphthalene and the like and polyfunctional (meth)acrylic compounds such as glycerol di(meth) acrylate, ethyleneglycol di(meth)acrylate, diethylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate, tetraethylene glycol di(meth)acrylate, pentaethylene glycol di(meth)acrylate, nonaethylene glycol di(meth)acrylate, dipropylene glycol di(meth)acrylate, tetrapropylene glycol di(meth)acrylate, 1,3-butylene glycol di(meth)acrylate, 1,4-butanediol di(meth)acrylate, trimethylolpropane tri(meth)acrylate, neopentyl glycol diacrylate, 1,6-hexamethylene di(meth)acrylate, hydroxypivalic acid ester neopentyl glycol di(meth)acrylate, pentaerythritol tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, dipentaerythritol penta(meth)acrylate, dipentaerythritol hexa(meth)acrylate, tris(meth)acryloxyethyl isocyanurate, 2,2'-bis(4-(meth)acryloxydiethoxypenyl)-propane, 2,2'-bis(4-(meth)acryloxypentaethoxyphenyl)-propane, 2,2'-bis(4-(meth)acryloxyethoxy-3,5-dibromophenyl)propane, 2,2'-bis(4-meth)acryloxydiethoxy-3,5-dibromophenyl)propane, 2,2'-bis(4-(meth)acryloxypentaethoxy-3,5-dibromophenyl)propane, 2,2'-bis(4-(meth)acryloxy-3,5-dibromophenyl)propane, 2,2'-bis(4-(meth)acryloxyethoxy-3,5-dichlorophenyl)propane, 2,2'-bis(4-(meth)acryloxyethoxy-3,5-dimethylphenyl)propane, 2,2'-bis(4-(meth)acryloxydiethoxy-3,5-dichlorophenyl)propane, 2,2'-bis(4-(meth)acryloxydiethoxy-3,5-dimethylphenyl)propane, 2,2'-bis(4-(meth)acryloxy-3,5-dimethylphenyl)propane and the like. Besides, allyl compounds such as diethylene glycol bisallyl carbonate, diallyl phthalate, dimethallyl phthalate, allyl methacrylate and the like may also be used. These diluent monomers may be used alone or in combination of 2 or more. As mentioned herebefore, it is necessary to improve operability for pouring and the material to be poured is preferably of low viscosity, low boiling point and low odor. Monomers having a boiling point of lower than 100°C, for example, methyl acrylate (boiling point: 78°C) has strong odor and high toxicity and is not suitable for pouring operation and is not preferred. Further preferable results can be obtained by using, alone or as a mixture, monomers represented by the following general formulas (II) and (III) as the radical polymerizable vinyl monomers (B) having a boiling point of 100°C or higher. (wherein R₃ and R₄ each denotes a hydrogen atom or a methyl group, R₅ denotes a phenyl, biphenyl, cyclohexyl, dicyclopentadienyl or adamantyl group and m and n each denotes an integer of 0 - 3). [wherein R₆ and R₇ each denotes a hydrogen atom or a methyl group, p denotes an integer of 0 - 5 and R₈ denotes (wherein X denotes a hydrogen atom, a chlorine atom or a bromine atom, R₉ denotes a hydrogen atom or a methyl group and q denotes an integer of 0 - 5)]. Among the monomers (B) represented by the general formula (II), tetrahydrofurfuryl (meth)acrylate, cyclohexyl (meth)acrylate, benzyl (meth)acrylate, phenyl (meth)acrylate, phenoxyethyl (meth)acrylate, dicyclopentenyl (meth)acrylate and biphenyl (meth)acrylate are suitable considering dilution effect, hardness of molded product, refractive index and colorless transparency. Among the monomers (B) represented by the general formula (III), the following are suitable in view of improvement in hardness and impact resistance of molded products: ethylene glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate, tetraethylene glycol di(meth)acrylate, nonaethylene glycol di(meth)acrylate, pentaethylene glycol di(meth)acrylate, 1,3-butylene glycol di(meth)acrylate, dipropylene glycol di(meth)acrylate, tetrapropylene glycol di(meth)acrylate, 2,2'-bis(4-(meth)acryloxydiethoxyphenyl)propane, 2,2'-bis(4-(meth)acryloxypentaethoxyphenyl)propane, 2,2'-bis(4-(meth)acryloxyethoxy-3,5-dibromophenyl)propane, 2,2'-bis(4-(meth)acryloxydiethoxy-3,5-dibromophenyl)propane and 2,2'-bis(4-(meth)acryloxypentaethoxy-3,5-dibromophenyl)propane. More preferably, the above monofunctional monomer and polyfunctional monomer are used in combination for improvement of casting operability of the composition for casting polymerization and hardness, impact resistance, refractive index and colorless transparency of molded products. The blending ratio is suitably 5 - 40 parts by weight of monofunctional monomer and 5 - 60 parts by weight of polyfunctional monomer for 40 - 90 parts by weight of urethane oligomer. By mixing the third component (C) in the present invention, namely, the photo-polymerization initiator represented by the general formula (I): (wherein R₁ and R₂ each denotes a phenyl group, a methoxy group, an ethoxy group or an isopropyloxy group) with the above mentioned components (A) and (B), no yellowing occurs with actinic rays such as ultraviolet ray, the composition can be cured rapidly and good deep curability and surface hardness can be imparted to cured product. As examples of the photo-initiators represented by the general formula (I), mention may be made of 2,4,6-trimethylbenzoyldiphenylphosphine oxide, methyl phenyl (2,4,6-trimethyl benzoyl)phosphinate, ethyl phenyl (2,4,6-trimethyl benzoyl)phosphinate, isopropyl phenyl (2,4,6-trimethyl benzoyl)phosphinate, dimethyl 2,4,6-trimethyl benzoyl phosphonate, diisopropyl 2,4,6-trimethyl benzoyl phosphonate, etc. Acylalkylphosphine oxides, phosphinic acid esters or phosphonic acid diesters represented by the general formula (I) among the photo-initiators in the present invention are sensitive to actinic rays in the range of wavelength of 370 - 390 nm, which is longer than 330-360 nm which is a wavelength range to which ordinary photo-initiators for ultraviolet rays are sensitive and hence they are especially excellent in deep curability. Among them, 2,4,6-trimethylbenzoyldiphenylphosphine oxide is most suitable considering its high storage stability and high molecule absorptivity coefficient. Ultraviolet ray absorbers are often used in production of molded products by casting polymerization for improvement of weather resistance. In this case, also said 2,4,6-trimethylbenzoyldiphenylphosphine oxide is especially preferred because the ultraviolet ray absorbers and 2,4,6-trimethylbenzoyldiphenylphosphine oxide are different in wavelength to which they are sensitive and hence molding with inexpensive high pressure mercury lamps is possible. In order to further increase reactivity, fusion lamp (V bulb) which has at least 50% of emission wavelength distribution intensity in 350 - 450 nm is preferred. In practice of the present invention, 40 - 90% by weight of terminal (meth) acryloyl group-containing oligomer (A) which is the first component is blended with 10 - 60% by weight of reactive diluent monomer (B) having a boiling point of 100°C or higher which is the second component and then, 0.005 - 5 parts by weight (per 100 parts by weight of component (A) + component (B)) of photo-initiator (C) which is the third component is mixed with the mixture of components (A) and (B). In order to obtain a deep curability of 10 mm or more it is preferred to add 0.005 - 0.5 part by weight of photo-initiator (C). When an amount of the terminal (meth)acryloyl group-containing oligomer (A) is less than 40% by weight, activity to ultraviolet ray tends to decrease, causing reduction in hardness, wear resistance, heat resistance and impact resistance. When an amount of the third component photo-initiator (C) is less than 0.005 part by weight, activity to actinic rays tends to decrease and even when it is added in an amount of more than 5 parts by weight, effect thereof cannot be expected so much and this is not preferred from the point of cost. Ultraviolet rays are preferred for polymerization curing of monomer mixture by irradiation with ultraviolet rays. Normal air atmosphere is sufficient as atmosphere for the irradiation. Ordinary chemical lamp, xenon lamp, low pressure mercury lamp and high pressure mercury lamp can be used as a light source. Furthermore, known methods of polymerization curing by irradiation with X-rays, electron rays, visible rays may also be used in addition to the above mentioned irradiation with ultraviolet rays. Besides, as far as the effects of the present invention are not damaged, there may be added at polymerization step various ultraviolet curing monomers, oligomers and other copolymerizable monomers, non-reactive materials for prevention of shrinking, for example, polyethylene glycol, polypropylene glycol, polyethylene glycol monoalkyl ether, polypropylene glycol monoalkyl ether, ethylene oxide or propylene oxide adduct of bisphenol A, ethylene oxide or propylene oxide adduct of tetrabromobisphenol A, various peroxides, anti-yellowing agents such as triphenylphosphine, ultraviolet ray absorbers, blue ink dyes, etc. Examples The present invention is explained in more detail in the examples, wherein part is by weight. Properties referred to in the examples were measured by the following methods. (1) Depth of curing: Resin composition was poured into a polyethylene test tube of 8 mm in internal diameter and 10 mm in outer diameter covered with aluminum foil on side surface and bottom surface and then the tube was capped by a transparent polyester film. Thereafter, the tube was irradiated from above with ultraviolet ray emitted from a high pressure mercury lamp of 80 W/cm for about 30 seconds and cured product was taken out. Hardness of side portion of the product was measured by Shore D type hardness meter and depth of the portion having a hardness of 70 or more was measured. Test piece used in the following items (2) - (8) was a plate of 2 mm or 10 mm (thickness) x 100 mm x 100 mm made by the following method: That is, resin composition was poured into a casting mold composed of two tempered glasses of 3 mm (thickness) x 150 mm x 150 mm and a gasket made of vinyl chloride. The composition was irradiated for 30 seconds through the glass of one side with ultraviolet ray emitted from 6 kw high pressure mercury lamp positioned at a distance of 10 cm from the mold (integrated light volume 3000 mj/cm²). The composition molded was released from the glass mold and kept at 110°C for 1 hour to remove internal strain of the molded product. (2) Pencil hardness: Measured according to JIS-K 5400. (3) Coloration: Y.I. (yellow index) of the cured product was measured according to JIS-K 7103. (4) Transmittance of visible ray: Measured according to ASTM D1003-61. (5) Refractive index: Measured with D-line of 589.3 nm by Abbe refractometer. (6) Operability for pouring: This was evaluated by the degree of difficulty for pouring the monomer composition into the mold. (7) Impact resistance: The test plate of 2 mm thick was subjected to falling ball test from height of 127 cm in accordance with FDA standard. The heaviest weight (g) of steel sphere by which the plate was not broken was measured. (8) Heat resistance: Surface state (crack, distortion, etc.) and yellowing degree were visually evaluated after heat treatments of 85°C x 200 hr and 120°C x 5 hr. Synthesis Example 1 (Preparation of urethane dimethacrylate (UDM1)) 244 Parts of m-tetramethylxylene diisocyanate and 0.3 part of hydroquinone monomethyl ether were charged in a three necked flask and thereto was added dropwise a mixture of 302 parts of 2-hydroxypropyl methacrylate and 0.3 part of n-butyl tin dilaurate over a period of 3 hours with stirring at 60°C. After completion of the addition, reaction was allowed to proceed for 8 hours at 70°C to obtain urethane dimethacrylate UDM1. 〈Production of actinic ray curable composition〉 Example 1 70 Parts of urethane dimethacrylate (UDM1) obtained in the above Synthesis Example 1 was mixed with 20 parts of benzyl methacrylate, 10 parts of pentaetylene glycol diacrylate and 0.05 part of 2,4,6-trimethylbenzoyldiphenylphosphine oxide and well stirred at room temperature. Then, this monomer mixture was poured into said polyethylene tube and glass mold for preparation of plate. The compositions in the polyethylene tube and the mold were irradiated from above or from side with UV ray by a 80 W/cm high pressure mercury lamp and the cured compositions were taken out. These cured compositions were measured on curing depth and surface hardness, pencil hardness, coloration, visible ray transmittance, impact resistance and heat resistance. Casting operability was evaluated at the time of pouring. The results are as shown in Table 1. The cured products were colorless and transparent and had a surface hardness of 4H in pencil hardness and were also superior in other properties. Thus, they were satisfactory as optical materials. Viscosity of the composition was low, namely, 500 cps at 25°C and pouring operability was superior. Further, the cured product was superior in properties such as impact resistance and did not yellow even after heat resistant test. Synthesis Example 2 (Preparation of urethane dimethacrylate (UDM2)) 488 Parts of m-tetramethylxylene diisocyanate and 0.3 part of hydroquinone monomethyl ether were charged in a three necked flask and thereto was added dropwise a mixture of 295 parts of 2-hydroxypropyl methacrylate and 0.3 part of n-butyl tin dilaurate over a period of 3 hours at 60°C with stirring. After completion of the addition, reaction was further allowed to proceed for 2 hours at 70°C, followed by cooling at 60°C. To the reaction mixture was added dropwise 426 parts of bis(diethoxyphenyl)sulfone over a period of 3 hours. After completion of the reaction, reaction was allowed to proceed for 5 hours at 70°C to obtain urethane dimethacrylate (UDM2). 〈Production of actinic ray curable composition〉 Examples 2-10 and Comparative Examples 1-10 In the same manner as in Example 1, compositions were prepared using the components (A), (B) and (C) shown in Table 1 and properties of cured products were evaluated. The results are shown in Table 1. Abbreviations of monomers in Table 1 stand for the following compounds. UDM1: Urethane dimethacrylate obtained by reaction of m-tetramethylxylene diisocyanate with 2-hydroxypropyl methacrylate. UDM2: Urethane dimethacrylate obtained by reaction of 2 mole of m-tetramethylxylene diisocyanate with 1 mol of bis(diethoxyphenyl)sulfone and 2 mols of 2-hydroxypropyl methacrylate. UDM3: Urethane diacrylate obtained by reaction of m-tetramethylxylene diisocyanate/p-tetramethylxylene diisocyanate = 1/1 with 2-hydroxyethyl acrylate. UDM4: Urethane dimethacrylate obtained by reaction of 2 mols of m-tetramethylxylene diisocyanate with 1 mol of 2,2'-bis(diethoxy 3,5-dibromophenyl)propane and 2 mols of 2-hydroxypropyl methacrylate. 5EOA: Pentaethylene glycol diacrylate. BzMA: Benzyl methacrylate. THFM: Tetrahydrofurfuryl methacrylate. PhOA: Phenoxyethyl acrylate. BphM: Biphenyl methacrylate. CHM: Cyclohexyl methacrylate. MA: Methyl acrylate. MMA: Methyl methacrylate. DGB: Diethylene glycol bisallyl carbonate. EDM: Ethylene glycol dimethacrylate. B2EOA: 2,2'-Bis(4-acryloxydiethylenoxyphenyl)propane. B5EOM: 2,2'-Bis(4-methacryloxypentaethylenoxyphenyl)propane. TBM: 2,2'-Bis(4-methacryloxyethylenoxy-3,5-dibromophenyl)propane. ST: Styrene. Oi 1: 2,4,6-Trimethylbenzoyldiphenylphosphine oxide. Oi 2: Methyl phenyl (2,4,6-trimethyl benzoyl)phosphinate Oi 3: 2-Hydroxy-2-methyl-1-phenylpropane-1-one. Oi 4: 1-Hydroxycyclohexylphenyl ketone Oi 5: Methyl phenylglyoxylate Oi 6: Acetophenone. Oi 7: α,α-Diethoxyacetophenone Oi 8: Benzophenone. Oi 9: 2-Methyl-1-[4-(methylthio)phenyl]-2-morpholino-1-propanone Oi 10: 2-Chlorothioxanthone. Oi 11: Benzoinethyl ether. Hi 1: Diisopropylperoxy percarbonate. Hi 2: Azobisbutyronitrile. Industrial Applicability The present invention provides actinic ray curable compositions for casting polymerization and a casting polymerization molded products which are superior in impact strength, heat resistance and optical characteristics and are markedly improved in coloration, optical strain and stress strain and which can be suitably used for optical and electrical uses.

Claims: An actinic ray curable composition for casting polymerization which comprises: (A) 40 - 90 parts by weight of an urethane poly(meth)acrylate having at least two (meth)acryloyl groups in one molecule which is obtained by addition reaction of a polyisocyanate represented by the general formula (IV): wherein Ar represents phenylene, biphenylene, naphthylene or methane-bisphenylene, and a hydroxyl group containing (meth)acrylate, (B) 10 - 60 parts by weight of a radical polymerizable vinyl monomer having a boiling point of 100°C or higher, and (C) 0.005 - 5 parts by weight, per 100 parts by weight of total of the above components (A) and (B), of a photo-initiator represented by the general formula (I): (wherein R₁ and R₂ which may be identical or different each represents a phenyl group, a methoxy group, an ethoxy group or an isopropyloxy group). An actinic ray curable composition for casting polymerization according to claim 1 wherein the radical polymerizable vinyl monomer (B) having a boiling point of 100°C or higher is at least one monomer represented by the general formulas (II) and/or the general formula (III): (wherein R₃ and R₄ each represents a hydrogen atom or a methyl group, R₅ represents a phenyl group, a biphenyl group, a cyclohexyl group, a dicyclopentadienyl group or an adamantyl group and m and n each represents an integer of 0 - 3) [wherein R₆ and R₇ each represents a hydrogen atom or a methyl group, p represents an integer of 0 - 5 and R₈ represents (wherein x represents a hydrogen atom, a chlorine atom or a bromine atom, R₉ represents a hydrogen atom or a methyl group and q represents an integer of 0 - 5)]. An actinic ray curable composition for casting polymerization according to claim 2 wherein the radical polymerizable vinyl monomer (B) represented by the general formula (II) is at least ono selected from benzyl (meth)acrylate, phenyl (meth)acrylate, phenoxyethyl (meth)acrylate, biphenyl (meth)acrylate and cyclohexyl (meth)acrylate. An actinic ray curable composition for casting polymerization according to claim 2 wherein the radical polymerizable vinyl monomer (B) represented by the general formula (III) is at least one selected from ethylene glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate, tetraethylene glycol di(meth)acrylate, pentaethylene glycol di(meth)acrylate, 1,3-butylene glycol di(meth)acrylate, dipropylene glycol di(meth)acrylate, tetrapropylene glycol di(meth)acrylate, 2,2'-bis(4-(meth)acryloxydiethoxyphenyl)propane, 2,2'-bis(4-(meth)acryloxypentaethoxyphenyl)propane, 2,2'-bis(4-(meth)acryloxyethoxy-3,5-dibromophenyl)propane, 2,2'-bis(4-(meth)acryloxydiethoxy-3,5-dibromophenyl)propane and 2,2'-bis(4-(meth)acryloxypentaethoxy-3,5-dibromophenyl)propane. An actinic ray curable composition for casting polymerization according to claim 1 wherein the radical polymerizable vinyl monomer (B) having a boiling point of 100°C or higher is 5 - 40 parts by weight of at least one monofunctional monomer selected from benzyl (meth)acrylate, phenyl (meth)acrylate, phenoxyethyl (meth)acrylate, biphenyl (meth)acrylate and cyclohexyl (meth)acrylate and/or 5 - 60 parts by weight of at least one polyfunctional monomer selected from ethylene glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate, tetraethylene glycol di(meth)acrylate, pentaethylene glycol di(meth)acrylate, 1,3-butylene glycol di(meth)acrylate, dipropylene glycol di(meth)acrylate, tetrapropylene glycol di(meth)acrylate, 2,2'-bis(4-(meth)acryloxydiethoxyphenyl)propane, 2,2'-bis(4-meth)acryloxypentaethoxyphenyl)propane, 2,2'-bis(4-(meth)acryloxyethoxy-3,5-dibromophenyl)propane, 2,2'-bis(4-(meth)acryloxydiethoxy-3,5-dibromophenyl)propane and 2,2'-bis(4-(meth)acryloxypentaethoxy-3,5-dibromophenyl)propane. An actinic ray curable composition for casting polymerization according to claim 1 wherein the polyisocyanate represented by the general formula (IV) is at least one selected from m-tetramethylxylene diisocyanate and p-tetramethylxylene diisocyanate. An actinic ray curable composition for casting polymerization according to claim 1 wherein the urethane poly(meth)acrylate (A) having at least two (meth)acryloyl groups in one molecule is selected from urethane di(meth)acrylates represented by the general formula (V): (wherein R₁₀, R₁₁ and R₁₂ each represents a hydrogen atom or a methyl group, r and s each represents an integer of 1 - 5, R₁₃ represents and Y represents a polyisocyanate residue). An actinic ray curable composition for casting polymerization according to claim 7 wherein the polyisocyanate residue represented by Y in the urethane di(meth)acrylate mentioned in claim 7 is a diisocyanate which originates from urethane di(meth)acrylate obtained by reacting the polyisocyanate represented by the general formula (IV) with the hydroxyl group-containing (meth)acrylate. An actinic ray curable composition for casting polymerization according to claim 8 wherein the diisocyanate represented by the general formula (IV) in the urethane di(meth)acrylates mentioned in claim 8 is a diisocyanate selected from m-tetramethylxylene diisocyanate and p-tetramethylxylene diisocyanate. An actinic ray curable composition for casting polymerization according to claim 1 wherein the polymerization initiator (C) is 2,4,6-trimethylbenzoyldiphenylphosphine oxide and is used in an amount of 0.005 - 0.5 part by weight per 100 parts by weight of casting polymerization composition. Cast polymerized molded products obtained by radiation polymerising a composition according to anyone of claims 1 to 10.

Inventors: AOSAI, FUMITO, FUKUSHIMA, HIROSHI, HADO, HISAKO
Applicants: MITSUBISHI RAYON CO., LTD.
Application year: 1988
Main classification: C08F299
IPC codes: C08F299