JPS6253002B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a method for producing a resin for plastic lenses having excellent transparency and a high refractive index.

[Prior art]

Plastic lenses are becoming widely used as optical components due to their advantages of being lightweight, easy to mold, and highly safe. There are already resins for plastic lenses such as polymethyl methacrylate and polydiethylene glycol bisallyl carbonate, which are also used for eyeglass lenses, but these resins have a low refractive index (n _D ≒ 1.50), so they are not suitable for use as camera lenses. When used, it becomes necessary to reduce the radius of curvature of the lens, resulting in larger aberrations than inorganic glass, making it difficult to increase the aperture and magnification. As a highly familiar resin with a high refractive index,
There are polycarbonate (n _D =1.58), polystyrene (n _D =1.59), etc., but their refractive index is still lower than that of glass. Furthermore, these resins are prone to birefringence, which causes problems with variations in optical properties.
It cannot be used as a resin for camera lenses. As described above, it is currently difficult to find resins for plastic lenses that have a high refractive index, especially a refractive index of 1.6 or higher.

One effective method for increasing the refractive index of plastics is to introduce heavy metals into them. Prior art for transparent resins containing heavy metals include JP-A-53-9995 and JP-A-53-9995.
No. 9996, JP-A-53-63310, JP-A-55-92340
There are radiation shielding materials containing lead, such as Japanese Patent Application Publication No. 55-151004 and Japanese Patent Application Publication No. 151005. In addition, regarding transparent resins containing itaconic acid monoalkyl ester metal salts, Carpenter Examination Report, 27 , 129~
141 (1976), etc. However, these transparent resins have a refractive index of n _D = 1.57 at most,
It does not reach a value of n _D = 1.60 or more.

On the other hand, as a technology related to metal-containing plastic lens materials with n _D = 1.60 or more, Japanese Patent Application Laid-Open No. 56-147101
JP-A-57-5705, JP-A-57-28115, JP-A-57-28116, etc. In these publications, monomers with covalently bonded metals or metal salts of organic carboxylic acids containing double bonds are polymerized alone or copolymerized with other reactive monomers to form resins. It has been proposed to introduce metals into However, when polymerizing a metal-containing monomer by mixing it with a reactive monomer such as styrene or halogenated styrene, the resulting resin generally decreases as the amount of the metal-containing monomer increases. Optical transparency is lost and it becomes white, translucent or opaque. Among metal salts of organic carboxylic acids, barium salts and lanthanum salts of methacrylic acid, for example, are white powders that are insoluble in reactive monomers and do not melt, so they are used as raw materials for transparent resins. Already known to be inappropriate. Therefore, the above method is severely limited in increasing the refractive index of the resin and improving other properties using the metal monomer.

Furthermore, the above-mentioned JP-A-56-147101 and JP-A-57
-No. 5705 states that many reaction steps are required to produce a new monomer containing metals, and these reactions tend to leave unreacted substances as impurities, making it difficult to produce uniform monomers. Have difficulty. Therefore, plastic lenses manufactured using these monomers do not yet have sufficient transparency and lack optical homogeneity.

Therefore, the present inventors have developed a resin that contains a sufficient amount of metal in the polymer to exhibit a sufficient effect of increasing the refractive index of the resin and has a high degree of optical transparency, and a method for producing the same. , conducted extensive research. As a result, it was discovered that a resin having desired excellent properties could be obtained, and the present invention was achieved.

[Purpose of the invention]

An object of the present invention is to provide a method for producing a resin for plastic lenses that has a high degree of optical transparency and a high refractive index, specifically, a refractive index of n _D =1.60 or more.

[Summary of the invention]

To summarize the present invention, the present invention is an invention of a method for producing a high refractive index resin, which comprises carbon dioxide containing a benzene nucleus in at least one vinyl monomer selected from the group consisting of styrene and styrene derivatives. It is characterized in that an organic acid mixture containing an acid and further methacrylic acid and/or acrylic acid is reacted with a metal compound, and then the obtained metal-containing monomer composition is polymerized.

It is expected that after the organic carboxylic acid mixture and the metal compound are reacted in the vinyl monomer according to the present invention to produce the metal salt of the organic carboxylic acid, the polymerized resin will maintain a high degree of optical transparency. The mechanism of action is not necessarily clear. However, among organic carboxylic acids, even if a metal salt of one type of carboxylic acid, such as methacrylic acid, is produced and copolymerized with other reactive monomers, optical transparency cannot be maintained at a high level. It was found that a high degree of optical transparency could be exhibited for the first time by newly using another organic carboxylic acid in combination to form a metal salt of a mixture of two or more organic acids.

Furthermore, if a saturated and/or unsaturated carboxylic acid with a long-chain aliphatic hydrocarbon group is used as an organic carboxylic acid in combination with methacrylic acid, etc., the refractive index of the plastic after polymerization may be lowered. At the same time, it is not heat resistant and causes yellowing of the plastic. For this purpose, if a saturated carboxylic acid and/or an unsaturated carboxylic acid containing a benzene nucleus and having a not too long chain length is used as the organic carboxylic acid used in combination, a resin for plastic lenses having a refractive index n _D = 1.60 or more can be obtained. I found out that it is possible.

The vinyl monomer used in the present invention is a monomer selected from the group consisting of styrene and styrene derivatives, and the styrene derivatives include styrene containing an epoxy group such as styrene oxide, nitrated styrene, halogenated styrene, There are styrenes with nuclear substitution such as amino-substituted styrene and carboxylated styrene, and styrenes with halogen (excluding fluorine atoms), cyano, amino, or other substituents at the α or β position. These can be used alone or in combination of two or more.

In the present invention, examples of the saturated and/or unsaturated carboxylic acids containing a benzene nucleus include those represented by the following general formula.

(R ₁ is alkyl, alkenyl, aryl,
Represents an aralkyl or cycloalkyl group. ) (f=0~3, g=0~3, _R2 , _R3 are hydrogen,
Represents an alkyl, chlorine, bromine or cyano group. ) In each of the above formulas, X represents hydrogen, chlorine, bromine, methoxy, amino, nitro, cyano, phenyl or phenoxy group, and a represents 1 or 2.

Examples of formula () are benzoic acid, phenylacetic acid, hydrocinnamic acid, 4-phenylbutyric acid, 5-phenylvaleric acid, o, m or p-chlorophenylacetic acid, 2-phenylpropionic acid, 2-phenyl-
Examples include n-butyric acid and 3-phenyl-n-butyric acid. Examples of formula () include phenoxyacetic acid, 3-phenoxypropionic acid, o- or p-chlorophenoxyacetic acid, and the like. Examples of formula () include DL-phenylalanine, DL-p-chlorophenylalanine, and the like. Examples of formula () include monomethyl phthalate, monoethyl phthalate, monohexyl phthalate, monovinyl phthalate, allyl phthalate,
Examples include monobenzyl phthalate and monocyclohexyl terephthalate. Examples of formula () include cinnamic acid, α-methylcinnamic acid, β-methylcinnamic acid, α-cyanocinnamic acid, and the like. These materials can be used alone or in combination of two or more.

Furthermore, the acid used in combination with the saturated and/or unsaturated carboxylic acid containing a benzene nucleus is methacrylic acid and/or acrylic acid. If desired, monoalkyl itaconate such as monomethyl itaconate, monoethyl itaconate, etc. can also be used in combination.

In the present invention, as the metal compound, oxides, hydroxides, chlorides, nitrates, acetates, carbonates, etc. of lead, barium, lanthanum, titanium, zirconium, tantalum, thorium, and niobium can be used.
These metal compounds may be used alone or in combination of two or more.

The above are the components constituting the present invention. In order to obtain the highly transparent high refractive index plastic lens resin composition of the present invention, the vinyl monomer, carboxylic acid and metal compound are mixed in a predetermined ratio, and the resin composition is prepared at room temperature or under heating. Make a big deal,
Make it a clear homogeneous liquid. In this case, the amounts of the carboxylic acid and metal compound differ depending on their type. Therefore, if an excess of carboxylic acid metal salt is produced, a precipitate may form in the reaction vessel. In that case, it is necessary to filter the liquid after the completion of the reaction to make it a clear liquid. Further, since by-products produced by the reaction, water, unreacted substances, etc. are dissolved in these monomers, it is preferable to remove these by-products and the like under reduced pressure.

The initiator used when polymerizing the obtained monomer composition is a conventional initiator such as benzoyl peroxide, lauroyl peroxide, diisopropyl peroxydicarbonate, dimyristyl peroxydicarbonate, azobisisobutyronitrile, etc. Radical initiators can be used. Furthermore, the production of the resin for plastic lenses according to the present invention involves pouring a mixture of the monomer composition and a radical initiator into a mold assembled with a mold (glass mold or metal) and a gasket. This may be done by curing using means such as heating or ultraviolet irradiation. Of course, it is also possible to adopt a method of curing by irradiating with radiation without using an initiator.

[Embodiments of the invention]

EXAMPLES In order to explain the present invention more specifically, Examples and Comparative Examples will be described below, but the present invention is not limited to these Examples. In addition, the high refractive index resin obtained in Examples and Comparative Examples is
Various physical properties were measured using the following test methods.

(1) Refractive index (n _D ) and Atsube number The refractive index and Atsube number at 25° C. were measured using an Atsube refractometer. α-Monobromonaphthalin was used as a contact liquid.

(2) Light transmittance Measured on a 2 mm thick test piece using a haze meter (manufactured by Suga Test Instruments Co., Ltd.).

Example 1 27 parts of styrene (parts by weight, the same applies hereinafter), 16 parts of hydrocinnamic acid, 21 parts of methacrylic acid, and 36 parts of lead monoxide (PBO) were mixed and reacted at 60°C to form a transparent clarifier containing lead. A monomer composition was obtained. Next, using this monomer composition, 0.5 parts of diisopropyl peroxycarbonate as a polymerization initiator was added and mixed to 100 parts of the monomer composition, and a casting mold consisting of two glass molds and a gasket was prepared. Injected into mold. After curing by heating at 50°C for 5 hours and then at 100°C for 2 hours, a transparent polymerized lens was taken out. The optical properties of the obtained polymer lens are n ²⁵ _D =
1.624, Atsube's number = 31, and was sufficiently practical as a plastic cleanser. Furthermore, the light transmittance of the polymer made using this monomer composition was 90%.

Comparative Example 1 29 parts of styrene, 34 parts of methacrylic acid, and 37 parts of PBO were mixed and reacted at 60°C to obtain a transparent and clear monomer composition containing lead. Since this monomer precipitates lead methacrylate at room temperature, 0.5 part of lauroyl peroxide as a polymerization initiator was added and mixed to 100 parts of the monomer composition at 60°C, and the same procedure as in Example 1 was carried out. It was poured into a casting mold. Then at 70℃ for 5 hours.
After further heating and curing at 120° C. for 2 hours, the polymer lens was taken out. The obtained polymeric lens was white and translucent and could not be used as a plastic lens.

Example 2 17 parts styrene, 14 parts cinnamic acid, 29 parts methacrylic acid
After mixing and maintaining the mixture at 60°C, 40 parts of pbo was gradually added to carry out the reaction. Next, using this transparent and clear monomer composition, 0.3 parts of diisopropyl peroxycarbonate as a polymerization initiator was added and mixed to 100 parts of the monomer composition, and a plastic lens was poured in the same manner as in Example 1. Mold molded. The obtained polymer lens was transparent, and its optical properties were n ²⁵ _D =1.652 and Abbe's number = 26. Moreover, the light transmittance of this polymer was 85%.

Example 3 35 parts of 2,6-dichlorostyrene, 14 parts of n-phenylbutyric acid, and 17 parts of methacrylic acid were mixed, kept at 45°C, and then mixed with anhydrous barium hydroxide [Ba
34 parts of (OH) ₂ ] was added to carry out the reaction. This solution was returned to room temperature, filtered, and then water was removed under reduced pressure to obtain a monomer composition. 0.3 parts of diisopropyl peroxycarbonate as a polymerization initiator was added and mixed to 100 parts of the monomer composition, poured into a glass mold casting mold, and heated at 50°C for 5 hours and then at 90°C.
After holding for 2 hours, a pale yellow transparent polymer lens was obtained. The optical properties were n ²⁵ _D = 1.613 and Atsbe's number = 33. The light transmittance of this polymer was 88%.

Example 4 Mixed chlorostyrene (ortho/para=60/40)
After mixing 40 parts of o-chlorophenylacetic acid, 23 parts of o-chlorophenylacetic acid, and 20 parts of methacrylic acid and maintaining the mixture at 45°C, 17 parts of lanthanum hydroxide [La(OH) ₃ ] was added to carry out a reaction. This solution was returned to room temperature, filtered, and then water was removed under reduced pressure to obtain a monomer composition. To 100 parts of this monomer composition, 0.3 parts of diisopropyl peroxycarbonate was added and mixed, and the mixture was heated at 55°C for 6 hours at 90°C.
C. for 3 hours to obtain a transparent polymer lens. The optical properties were n ²⁵ _D = 1.620 and Atzbe's number = 35.
The light transmittance of this polymer was 89%.

Comparative example 2 Mixed chlorostyrene (ortho/para = 60/40)
45 parts of methacrylic acid, 36 parts of methacrylic acid, and 19 parts of La(OH) ₃ were added to carry out the reaction. A plastic lens was cast in the same manner as in Example 4. The obtained polymer lens was severely cloudy and could not be used as a plastic lens. The light transmittance of this polymer was 30%.

Example 5 20 parts of styrene, mixed chlorostyrene (ortho/
Mix 7 parts of para=60/40), 16 parts of hydrocinnamic acid, 21 parts of methacrylic acid, and 36 parts of lead monoxide (pbo),
The reaction was carried out at 50°C to obtain a transparent and clear monomer composition containing lead. A plastic lens was cast in the same manner as in Example 1. The optical properties of the obtained polymer lens were n ²⁵ _D =1.626 and Abbe's number = 31. The light transmittance of this polymer was 90%.

Example 6 Mixed chlorostyrene (ortho/para=60/40)
37 parts, 3-phenyl-n-butyric acid 18 parts, acrylic acid
20 parts of PBO and 25 parts of PBO were mixed and reacted at 50°C to obtain a transparent and clear monomer composition containing lead. Example 1
A plastic lens was cast and molded in the same manner as described above. The obtained polymer lens was transparent, and its optical properties were n ²⁵ _D =1.609 and Abbe's number = 33.
The light transmittance of this polymer was 89%.

Example 7 29 parts of styrene, 8 parts of cinnamic acid, 25 parts of methacrylic acid
After mixing 1 part and 4 parts of itaconic acid monomethyl ester and maintaining the mixture at 60°C, 34 parts of PBO was gradually added to carry out the reaction to obtain a transparent monomer composition containing lead. A plastic lens was cast in the same manner as in Example 1. The optical properties of the obtained polymer lens were n ²⁵ _D =1.637 and Abbe's number = 29. Moreover, the light transmittance of this polymer was 87%.

Example 8 Mixed chlorostyrene (ortho/para = 60/40)
28 parts of 3-phenoxypropionic acid, 21 parts of methacrylic acid, and 33 parts of PBO were mixed and reacted at 50°C to obtain a transparent and clear monomer composition containing lead. A plastic lens was cast in the same manner as in Example 1. The optical properties of the obtained polymer lens were n ²⁵ _D =1.622 and Abbe's number = 32. The light transmittance of this polymer was 89%.

Example 9 32 parts of 2,6-dichlorostyrene, 14 parts of DL-phenylalanine, and 20 parts of methacrylic acid were mixed to make 40
After maintaining the temperature at 0.degree. C., 34 parts of anhydrous barium hydroxide was mixed and a reaction was carried out. Return this solution to room temperature,
After filtration, water was removed under reduced pressure to obtain a monomer composition. A plastic lens was cast in the same manner as in Example 3. This polymer lens is pale yellow and transparent, but has optical properties of n ²⁵ _D = 1.615 and Atsube's number = 32, and the light transmittance of this polymer is 88%.
It was hot.

Example 10 27 parts of styrene, 21 parts of monoethyl phthalate, 20 parts of methacrylic acid, and 32 parts of lead monoxide were mixed and reacted at 60°C to obtain a clear and transparent monomer composition containing lead. A plastic lens was cast in the same manner as in Example 1. The optical properties of the obtained polymer lens were n ²⁵ _D =1.620 and Abbe's number = 32. The light transmittance of this polymer was 90%.

〔Effect of the invention〕

As described above, according to the present invention, a high refractive index plastic lens having a high degree of optical transparency can be produced by polymerizing a salt of a carboxylic acid mixture in a styrene derivative. , the industrial value of the present invention is extremely high.

Claims (1)

[Scope of Claims] 1. An organic acid mixture containing a carboxylic acid containing a benzene nucleus and further containing methacrylic acid and/or acrylic acid in at least one vinyl monomer selected from the group consisting of styrene and styrene derivatives. 1. A method for producing a high refractive index resin, which comprises reacting with a metal compound and then polymerizing the obtained metal-containing monomer composition. 2. The method for producing a high refractive index resin according to claim 1, wherein the organic acid mixture contains monoalkyl itaconate. 3. Claims 1 or 2, wherein the metal compound is one or more metal compounds selected from the group of compounds of lead, barium, lanthanum, titanium, zirconium, tantalum, thorium, and niobium. A method for producing high refractive index resin.