JPH0580201A - Sulfur atom-containing polyurethane plastic lens - Google Patents

Abstract

PURPOSE:To obtain a plastic lens having a high refractive index and capable of reducing its thickness. CONSTITUTION:Bi- or higher functional polyisocyanate is allowed to react with polyols including one or more kinds of polyol compds. having) >=20wt.% sulfur atom content in 0.5-1.5 molar ratio of -NCO to -OH to obtain a plastic lens. This plastic lens has a high refractive index, is tough, colorless and transparent, also has excellent impact resistance, satisfactory machinability and grindability, excellent workability, a relatively low coefft. of shrinkage at the time of molding and polymn. and relatively low specific gravity and is light in weight.

Description

[Detailed description of the invention]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sulfur (S) atom-containing polyurethane-based plastic lens having a high refractive index and excellent workability such as machinability and polishing.

[0002]

2. Description of the Related Art Plastic lenses are lighter, more resistant to cracking, and more dyeable than inorganic glass lenses. is prevalent in A representative plastic lens widely used for this purpose at present is one obtained by radically polymerizing diethylene glycol bisallyl carbonate (hereinafter this polymer is abbreviated as a DAC lens). This DAC
The lens should have excellent impact resistance, the lens power should not change greatly due to changes in temperature, it should be lightweight, it should have excellent dyeability, and it should have good workability such as machinability and polishability. However, in the field of spectacle lenses, it cannot be said that the DAC lens has sufficient functions as a lens in the recent trend of lens fashion.

[0003] That is, the biggest drawback of the DAC lens is
The refractive index is lower than that of inorganic lenses (inorganic lens refractive index N
^D20 ° _C = ^1.52 , DAC lens refractive index N _D20
°C = 1.50), and when processed into a lens, the thickness of the lens increases. Especially in strong myopia spectacle lenses, the thickness of the rim of the lens is large, so not only is it inferior to weight reduction, but also the recent trend of valuing fashionableness due to poor appearance, lenses using DAC as a raw material tend to be avoided. be. Therefore, there is a demand for a plastic lens having a high refractive index, that is, a plastic lens having a thickness smaller than that of a DAC lens.

[0004]

SUMMARY OF THE INVENTION The present inventors arrived at the present invention as a result of intensive studies on a lens that eliminates the drawbacks of the DAC lens and the like, provides a high refractive index, and is easy to process. That is, the present invention combines a polyisocyanate having at least two functional groups and a polyol containing at least one polyol compound having a sulfur atom and having a sulfur atom content of at least 20% by weight or more, and --NCO group/
A sulfur atom-containing polyurethane-based plastic lens obtained by reacting -OH groups at a ratio of 0.5 to 1.5 mol is provided.

A urethane-based lens is known as one of plastic lenses giving a high refractive index. For example, a reaction between an isocyanate compound and a hydroxy compound such as diethylene glycol 136602) or a urethane lens obtained by reaction with a hydroxyl compound containing a halogen atom such as tetrabromobisphenol A (JP-A-58-164615). However, these _urethane -based ^lenses have a limit in obtaining a high refractive index.
= 1.60 or more, it is necessary to use a large amount of aromatic isocyanates and halogen atoms. A problem arises.

In contrast, when the urethane-based plastic lens containing sulfur (S) atoms according to the present invention is used, a lens having a refractive index N _D ²⁰ ° C. of 1.56 or more can be obtained, and the appearance such as coloring is not observed. and weather resistance. In the above-described urethane-based lens, unless a trifunctional or higher-functional compound is added, it tends to be inferior in workability such as machinability and polishability. Even without adding an agent, it is possible to obtain a plastic lens having good workability such as machinability and polishability.

[0007] In the present invention, the polyfunctional polyisocyanate used as a starting material may be a single compound alone or a mixture of two or more of them. compounds are good. Also aromatic,
Any aliphatic compound may be used, and the aromatic compound may be nucleus-substituted with halogen or the like.

[0008] These isocyanate compounds include:
For example, m-xylylene diisocyanate, p-xylylene diisocyanate, tetrachloro-m-xylylene diisocyanate, tetrachloro-p-xylylene diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, tolylene diisocyanate,
4,4′-diphenylmethane diisocyanate, biuret reaction product of hexamethylene diisocyanate,
Adduct reaction product of hexamethylene diisocyanate and trimethylolpropane, 4,4'-dichlorohexylmethane diisocyanate, lysine isocyanate-
β-isocyanate ethyl ester and the like, aromatic diisocyanates in which side chain alkyl groups are substituted with isocyanate groups such as m-xylylene diisocyanate, and hexamethylene diisocyanate and the like. Such aliphatic diisocyanates are particularly preferred compounds.

The polyol compound having S atoms may be a single compound or a mixture of two or more of them, but the main component must have at least two functional groups. Examples of polyol compounds containing these S atoms include di(2-hydroxyethyl)sulfide, 1,2-bis-(2-hydroxyethylmercapto)ethane, bis-(2-hydroxyethyl)disulfide, 1,4 -dithiane-2,5-diol and the like.

The polyurethane-based plastic lens according to the present invention may use these S-atom-containing polyol compounds alone or may be used in combination with S-atom-free polyol compounds. On the other hand, in reactions with isocyanates, at least 20% by weight
As described above, a desired plastic lens cannot be obtained unless a polyol containing 25 to 40% by weight of S atoms is used. In addition, the amount of polyol and polyisocyanate containing these S atoms used is N
A CO/OH molar ratio in the range of 0.5 to 1.5 should be used. Outside this range, the curing of the resin becomes insufficient, and other properties of the plastic lens deteriorate.

[0011] Further, within this molar range, in order to impart high hardness properties, trifunctional or higher polyfunctional polyisocyanates and polyfunctional polyols such as trimethylolpropane and pentaerythritol are appropriately used as three-dimensional cross-linking agents. preferably added. In addition, diethylene glycol bis(allyl carbonate) (DAC), acrylic acid ester, methacrylic acid ester, styrene derivative and other radical polymerization raw materials and their radical polymerization initiators, UV absorbers to improve light resistance, antioxidants, etc. are added in small amounts. There is absolutely no harm in adding.

A polyurethane plastic lens according to the present invention is manufactured as follows. A cast polymerization method is usually used as a lens manufacturing method, and a method by cast molding is preferable in the present invention as well. component) are mixed so that the molar ratio of —NCO to —OH is 0.5 to 1.5 molar ratio, and when uniform, deaeration is performed, and the mixed solution is placed in a glass or metal mold. is injected, the reaction proceeds at an appropriate temperature, and the liquid hardens. Although the A component and the B component often separate into two layers at first, the two layers become uniform as the reaction between the A component and the B component progresses. In addition, even if both the A component and the B component are sufficiently deaerated, when they become uniform and the polymerization reaction progresses, depending on the compound, the reaction may proceed explosively and may be accompanied by a foaming phenomenon, so sufficient heat removal is necessary. , with temperature control. Although the reaction completion time and reaction temperature differ depending on the combination of the A component and the B component, the polymerization is usually carried out at -20 to 80°C for 24 to 72 hours. The hardness does not increase any further as the reaction ends. This point may be the end point of polymerization or may be just before it. As long as the function as a lens is sufficiently maintained, the end point of polymerization can be set anywhere.
In these polymerizations, as mentioned above, the initial two components are often non-uniform, so it is particularly important to uniformly stir the reaction solution before curing so that the final polymer is not uneven.

[0013]

Effect of the Invention The polyurethane-based plastic lens according to the present invention obtained in this way has S atoms in the main chain, so that when processed into a lens, the refractive index is higher than that of known plastic lenses. In addition, it has the following features. 1. A tough plastic lens is obtained. 2. A colorless and transparent plastic lens is obtained. 3. Excellent impact resistance. 4. Good machinability and polishability, and excellent workability. 5. Relatively low shrinkage during molding polymerization. 6. Relatively small specific gravity and light weight.

The plastic lens of the present invention is further subjected to known physical or chemical treatments for surface modification such as antireflection, imparting high hardness, abrasion resistance, improving chemical resistance, and imparting antifogging properties. It is also possible to apply

[0015]

EXAMPLES The present invention will now be described in more detail with reference to examples and comparative examples. Example 1 9.4 g of m-xylylene diisocyanate as component A
(0.050 mol) and 4.3 g (0.050 mol) of di(2-hydroxyethyl) sulfide of component B are mixed,
Stir at around room temperature, and degas under ice-cooling after the mixture becomes homogeneous. Next, the liquid is poured into a lens glass mold that has been treated to facilitate peeling from the resin by a method such as making it hydrophobic or applying a release agent in advance, and the mold is heated at 0°C for 3 hours and at 20°C for 20 hours. It was allowed to react and hardened. The obtained lens molded product was extremely tough, colorless and transparent, had good impact resistance, had good machinability and ^{polishability} , had a high refractive index _ND20 °C of 1.59, and had a specific gravity of 1.24. rice field. Table 1 shows the results.

Examples 2 to 4 In the same manner as in Example 1, components A and B were mixed and homogenized as shown in Table 1. After deaeration, the liquid was poured into a lens glass mold and cured. Table 1 shows the results.

Comparative Example 1 m-xylylene diisocyanate 9.4 g (0.050
mol) and 5.3 g (0.050 mol) of diethylene glycol are mixed, heated and stirred at 40 to 50° C. to homogenize,
The heat of reaction was removed by water cooling. After degassing, the liquid was poured into the same lens glass mold as in Example 1 and heated at 20 to 30°C for 4 hours.
It took 8 hours to cure. As shown in Table 1, the lens molded product obtained was colorless and transparent, had good impact resistance, had a refractive index _ND20 °C of ^1.56 , and had a light specific gravity of 1.18. was of poor quality.

Comparative Examples 2 and 3 Components A and B were mixed and homogenized in the same manner as in Example 1 and Comparative Example 1. After degassing, the liquid was poured into a lens glass mold and cured. Table 1 shows the results.

[0019]

[Table 1]

[0020]

[Table 2]

Claims (1)

[Claims] 1. A polyisocyanate having at least two functional groups;
There is one or more polyol compounds having sulfur atoms,
and in that case a sulfur atom content of at least 20% by weight
-NCO group/-OH group = 0.5
A sulfur atom-containing polyurethane-based plastic lens obtained by reacting at a ratio of up to 1.5 mol.