JPH0618849B2 - Method for producing resin for high refractive index plastic lens - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for producing a plastic lens resin having a high refractive index, low dispersion, and excellent heat resistance.

[Problems to be Solved by Prior Art and Invention]

Compared with inorganic lenses, plastic lenses are less likely to be broken by weighing and can be dyed. Therefore, plastic lenses have recently come into widespread use in eyeglass lenses, camera lenses and optical elements.

As a resin widely used for these purposes, there is a resin obtained by radically polymerizing diethylene glycol bisallyl carbonate, but the refractive index (n _D ) of this is as small as 1.50 as compared with an inorganic lens (n _D = 1.52). In order to obtain the optical properties equivalent to those of the inorganic lens, it is necessary to increase the curvature of the lens. Therefore, the center thickness and the edge thickness of the lens are also increased, and the overall thickness is inevitable.
Therefore, a resin for lenses having a higher refractive index is desired. Therefore, a method of introducing an aromatic ring, a chlorine atom, or a bromine atom into the chemical structure of various monomers has been proposed, but it is difficult to obtain a high refractive index only by introducing an aromatic ring, and when a halogen atom is introduced, The specific gravity increases, and the lightness, which is an advantage of plastic lenses, is impaired.

The method of introducing a sulfur atom into the chemical structure of the monomer is
A sulfur-containing urethane resin (JP-A-60-194401 and JP-A-60-217229) has been proposed because of its high refractive index, low dispersion, and low specific gravity. Since it is inferior to that of the resin, deformation is likely to occur during lens dyeing and post-processing such as surface coating, and the processing temperature during post-processing must be kept low. There is.

[Means for Solving the Problems]

In view of such a situation, the inventors of the present invention, regarding the sulfur-containing urethane resin, while maintaining good physical properties as a lens such as high refractive index, low dispersion, and low specific gravity, after dyeing or surface coating. The inventors have made earnest studies on the production of a resin for a high refractive index lens capable of imparting heat resistance sufficient to withstand heating conditions in processing. As a result, the general formula (I) (In the formula, K is a substituent And R is a hydrogen atom or a methyl group, m is an integer of 0 to 3, n is 0 to 1, p is 0 to 1, and q is an integer of 1 to 3). It was found that a resin capable of achieving this purpose can be produced by mixing at least one bifunctional or more polyisocyanate with at least one of NCO / SH molar ratio in the range of 0.5 to 3.0 and polymerizing by heating. Invented.

That is, in the present invention, at least one or more polythiols represented by the general formula (I) and at least one or more bifunctional or more polyisocyanates are used in NCO / S.
A method for producing a resin for a high refractive index plastic lens having a high refractive index, low dispersion, low specific gravity and excellent heat resistance, which is characterized in that H mole ratio is mixed in a range of 0.5 to 3.0 and heat polymerization is performed.

Examples of the polyisocyanate having two or more functional groups used in the present invention include xylylene diisocyanate, nuclear chlorinated xylylene diisocyanate, α, α, α ′, α′-.
Tetramethylxylylene diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate,
Tolylene diisocyanate, 4,4′-diphenylmethane diisocyanate, biuretization reaction product of hexamethylene diisocyanate, adduct reaction product of hexamethylene diisocyanate and trimethylolpropane, trimerization of hexamethylene diisocyanate (isocyanurate), methyl Examples thereof include cyclohexane diisocyanate, 4,4′-dicyclohexylmethane diisocyanate, and lysine isocyanate-β-isocyanate ethyl ester, but from the viewpoint of weather resistance of the obtained resin, xylene diisocyanate, tetramethyl xylylene diisocyanate, and other aromatic compounds are used. Aromatic isocyanates in which the alkyl group of the ring side chain is replaced with an isocyanate group, isophorone diisocyanate, methylcyclohexanediisocyanate Sulfonates, aliphatic isocyanate such as hexamethylene diisocyanate are preferred.

The polythiol represented by the general formula (I) used in the present invention is, for example, tris (2-mercaptoethyl) isocyanurate or tris (3-mercapto-n-).
Propyl) isocyanurate, tris (2-methyl-3)
-Mercapto-n-propyl) isocyanurate, tris (mercaptomethyl) isocyanurate, tris (2
-Hydroxyethyl) isocyanuric acid mercaptopropionic acid ester, tris (2-hydroxyethyl) isocyanuric acid mercaptoacetic acid ester, tris (hydroxymethyl) isocyanuric acid mercaptopropionic acid ester, tris (hydroxymethyl) isocyanuric acid mercaptoacetic acid ester And so on.

The use ratio of at least one or more polythiols represented by the general formula (I) and at least one or more polyisocyanates having two or more functional groups in the present invention is NCO / S.
The H molar ratio is within the range of 0.5 to 3.0, preferably within the range of 0.5 to 1.5.

Further, in the present invention, in order to increase the degree of crosslinking of the resin, pentaerythritol, trimethylolpropane, pentaerythritol tetrakis (thioglycolate), pentaerythritol tetrakis (mercaptopropionate), trimethylolpropane tris (mercaptopropionate). , Trimethylolpropane tris (thioglycolate), polyol such as pyrogallol, and polythiol may be mixed. At that time, NC
When the O / (SH + OH) molar ratio is within the range of 0.5 to 3.0,
Preferably, the amount of polyisocyanate is increased so that it falls within the range of 0.5 to 1.5.

Further, in the present invention, in order to obtain a higher refractive index, polythiol having an aromatic ring such as xylylenedithiol, benzenedithiol, toluenedithiol, a nuclear halide thereof, or bismuthiol may be mixed. At that time, the NCO / SH molar ratio of all the monomers was 0.
The amount of polyisocyanate is increased so as to be in the range of 5 to 3.0, preferably 0.5 to 1.5.

In the present invention, a catalyst such as dibutyltin laurate, dimethyltin chloride or lead 2-ethylhexanoate may be added in an amount of 0.01 to 1.0% by weight in order to accelerate the polymerization of polyisocyanate and polythiol. Further, in the present invention, in order to maintain the physical properties of the obtained resin, additives such as an ultraviolet absorber, an antioxidant, a coloring preventing agent and a fluorescent dye may be appropriately added if necessary.

The lens resin of the present invention is produced by at least one polythiol represented by the general formula (I) and at least one polyisocyanate having two or more functional groups, and optionally a crosslinking agent for the above-mentioned polyol or polythiol,
Mixing a polythiol having an aromatic ring such as xylylenedithiol, and combining the known cast polymerization method, that is, a mold-treated glass or metal mold with a Teflon, polyethylene or PVC gasket. It is poured into a mold and heated to cure.

The reaction temperature and reaction time will differ depending on the type of monomer used, but are generally -20 to 150 ° C and 0.5 to 72 hours.

〔effect〕

According to the present invention, it is colorless and transparent and has a high refractive index, low dispersion, and low specific gravity, and deformation does not occur even with heating in post-processing such as dyeing and surface coating, and a spectacle lens,
Resins used for camera lenses and other optical elements can be manufactured.

〔Example〕

 Hereinafter, the present invention will be specifically described with reference to Examples.

In addition, the part in an Example shows a weight part. In addition, the methods for testing the refractive index, Abbe number, scoring workability, impact resistance and dyeability of the lens resins obtained in the examples depended on the following methods.

Refractive index, Abbe number: Measured at 20 ° C. using a Pulfrich refractometer.

Grinding workability: Grinding with a ball grinding machine for processing eyeglass lenses,
The one having a good ground surface was evaluated as good (◯), and the one that could not be ground due to clogging was evaluated as bad (x).

Impact resistance: Using a flat plate having a center thickness of 2 mm, a steel ball drop test was conducted in accordance with FDA standards, and those that did not crack were rated as good (○).

Dyeability: Miketone Polyester Red FB (manufactured by Mitsui Toatsu Dyes Co., Ltd.) 0.9 part, dialkyl sulfosuccinic acid 0.1 part and β
-Naphthalene sulfonic acid formalin condensate sodium salt 0.1 part is dispersed in water 300 parts, and Tetromin OEM (Yamakawa Yakuhin Kogyo Co., Ltd., orthophenylphenol carrier) 1.5 parts is added as a carrier agent, and then 85 ° C while stirring well. After soaking the lens in the dyebath heated to 1, keep it at the same temperature for 10 minutes, remove it from the dyebath and wash it thoroughly with water, and then color it in red and mark it as good (○). X).

Heat resistance: Using a thermomechanical analyzer [Perkin Elmer (USA)], 5 g of the test piece was weighted and heated at a temperature rising temperature of 2.5 ° C./min to measure the heat deformation start temperature.

Example 1 188 parts of m-xylylene diisocyanate, tris (3-
234 parts of mercapto-n-propyl) isocyanurate and 0.1 part of dibutyltin dilaurate were mixed, and the homogenized liquid was poured into a mold composed of a glass mother mold treated with a silicone-based baking type mold release agent and a polyethylene gasket. Next, 55 ℃ for 3 hours, 60 ℃ for 2 hours, 80 ℃
The lens obtained by releasing from the mold after heating for 1 hour at 90 ° C. for 1 hour and then releasing it has a refractive index (n ₂₀ ), 1.615, Abbe number 34, specific gravity 1.33, Both the impact resistance and the dyeability were good, and the thermal deformation starting temperature was 120 ° C.

Examples 2 to 15 Lenses having the compositions shown in Table 1 were prepared in the same manner as in Example 1,
The evaluation results are shown in Table 1.

Comparative Example 1 222 parts of isophorone diisocyanate, 244 parts of pentaerythritol tetrakis (mercaptopropionate) and 0.3 part of dibutyltin dilaurate were mixed and made into a uniform liquid, and a glass mother mold treated with a silicone-based baking type mold release agent. It was poured into a mold made of polyester gasket. Then, 55 ℃ for 3 hours, 60 ℃ for 3 hours, 80 ℃
The lens obtained by demolding after heating for 1 hour at 90 ° C for 1 hour at 100 ° C for 1 hour has a refractive index (n ₂₀ )
1.55, Abbe number 44, specific gravity 1.32, good ball-scraping workability, impact resistance, and dyeability, and thermal deformation start temperature is 90 ° C.
Met.

Comparative Example 2 As in Comparative Example 1, a lens having the composition shown in Table 1 was prepared without using the isocyanurate compound of the general formula (I), and the evaluation results are shown in Table 1.

Claims (6)

[Claims] 1. A general formula (I) (In the formula, K is a substituent And R is a hydrogen atom or a methyl group, m is an integer of 0 to 3, n is 0 to 1, p is 0 to 1, and q is an integer of 1 to 3). Is mixed with at least one bifunctional or higher polyisocyanate in an NCO / SH molar ratio of 0.5 to 3.0,
A method for producing a resin for a refractive index plastic lens, which comprises heat-polymerizing. 2. A polythiol is tris (3-mercapto-
The method for producing a resin for a high refractive index plastic lens according to claim 1, which is n-propyl) isocyanurate. 3. The method for producing a resin for a high refractive index plastic lens according to claim 1, wherein the polyisocyanate is xylylene diisocyanate. 4. The polyisocyanate is α, α, α ′, α ′.
-The method for producing a resin for a high refractive index plastic lens according to claim 1, which is tetramethylxylylene diisocyanate. 5. The method for producing a resin for a high refractive index plastic lens according to claim 1, wherein the polyisocyanate is isophorone diisocyanate. 6. The method for producing a resin for a high refractive index plastic lens according to claim 1, wherein the polyisocyanate is methylcyclohexane diisocyanate.