JPH0349401B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to optical elements made of polyurethane-based synthetic resins, and particularly to eyeglass lenses and other optical elements made of polyurethane-based synthetic resins obtained using specific sulfur-containing polyols as raw materials. Optical elements such as glasses, cameras, and projector lenses have traditionally been made of glass and certain synthetic resin materials. In particular, diethylene glycol bisallyl carbonate (hereinafter referred to as
DGBAC) and polymethyl methacrylate were widely used because they were lighter than glass, had superior transparency, and had low birefringence. However, since these synthetic resins have a low refractive index of approximately 1.5, their range of application has been inevitably limited. Moreover, with the recent progress in object electronics technology and the spread of copying machines, facsimile machines, video cameras, etc., we have been able to produce lenses with higher refractive indexes such as irregularly shaped lenses, Fresnel lenses, diffraction gratings, aspheric lenses, etc. at high speeds and with high speed. There is a growing demand for synthetic resin materials that can be manufactured with precision, and the development of new synthetic resin materials is desired. Taking eyeglass lenses as an example, most conventional synthetic resin eyeglass lenses are made of DGBAC polymer. DGBAC is famous as the product name "CR-39". In recent years, the development of synthetic resin materials for eyeglass lenses with high refractive index has progressed, and polymerizable monomers having a halogenated aromatic nucleus, particularly a brominated aromatic nucleus, are known as relatively successful examples. For example, a representative monomer is nuclear brominated bisphenol A.
Examples include derivatives of (meth)acrylic acid ester and nuclear brominated styrene. Although these polymers of brominated aromatic monomers have a refractive index close to about 1.6, they still have various problems in practical use as optical elements. The biggest problem with polymers of brominated aromatic monomers as optical elements is their weather resistance, particularly the fact that they are easily colored. Other traditional DGBAC such as hardness
Compared to polymers, properties other than refractive index are not fully satisfactory. The reason for the poor weather resistance of polymers of brominated aromatic monomers is thought to be that bromine atoms are easily detached from aromatic nuclei under the action of light and heat. Furthermore, bromine atoms are likely to be eliminated by the action of radical-generating polymerization initiators, and therefore, even if the monomer itself is sufficiently purified, the polymer is likely to be colored. Aromatic nuclei also have the effect of increasing the refractive index. Therefore, polymers of aromatic vinyl monomers (such as styrene) that do not contain halogens have a somewhat high refractive index and few problems in weather resistance, but are difficult to satisfy in terms of mechanical properties and the like. In addition, although the specific gravity of the polymer of brominated aromatic monomer is lighter than that of glass,
Another problem is that it is much more expensive than DGBAC polymers, and it is not necessarily sufficient in terms of weight reduction. The present inventors have studied synthetic resins for optical elements that can solve the above problems. Since it is difficult to obtain the desired refractive index with only aromatic nuclei, we conducted research on polymers that contain ingredients effective in improving the refractive index in addition to aromatic nuclei, and as a result, we synthesized a polyurethane system containing aromatic nuclei and sulfur atoms. The resin was found to be promising. Lenses made of polyurethane synthetic resin are basically known;
Publication No. 136601, West German Patent No. 2929313,
It is described in US Pat. No. 3,907,865, US Pat. No. 3,954,584, etc. However, these conventional optical elements were not always satisfactory due to reasons such as insufficient refractive index and insufficient weather resistance. The present inventors have specifically discovered that a polyurethane-based synthetic resin obtained using a sulfur-containing polyol as a raw material has a high refractive index as an optical element and also has excellent other physical properties such as weather resistance. The present invention relates to an optical element made of this specific polyurethane synthetic resin, that is, a divalent or higher residue represented by the following formula [] and a
A sulfur-containing polyol containing the above alcoholic hydroxyl group, or a combination of the sulfur-containing polyol and another polyvalent active hydrogen-containing compound, in which the proportion of the sulfur-containing polyol is at least 10% by weight;
An optical element made of a polyurethane synthetic resin obtained by reacting a polyisocyanate compound with a polyisocyanate compound. However, R ¹ , R ² : Same or different lower alkyl group, halogen atom, or bond k, l: 0, 1, or 2, respectively In the present invention, the polyisocyanate compound is preferably the non-yellowing polyisocyanate described below. be. Polyurethane-based synthetic resins obtained using yellow-modified polyisocyanates tend to yellow due to ultraviolet rays. Therefore, when used as an optical element with little risk of exposure to ultraviolet light, yellowing polyisocyanate can be used as a raw material. However, preferably non-yellowing polyisocyanates are used as polyisocyanate compounds. Similarly, it is more preferable that the sulfur-containing polyol does not contain halogen. However, polyurethane resins obtained using halogen-containing sulfur-containing polyols have better weather resistance and lower specific gravity than conventional polymers of halogen-containing aromatic monomers. The reason for the former is that the production of polyurethane synthetic resin does not require the use of a radical-generating polymerization initiator. Therefore, when a higher refractive index is required even if the weather resistance is low to some extent, it is preferable to use a halogen-containing sulfur-containing polyol. The sulfur-containing polyol in the present invention must contain a divalent residue represented by the above formula [] (hereinafter referred to as a sulfur-containing nucleus) and two or more alcoholic hydroxyl groups. A typical starting material for producing sulfur-containing polyols is diphenol having a sulfur-containing nucleus and two hydroxyl groups bonded to it. That is, dihydroxydiphenyl sulfide and its nuclear lower alkyl-substituted products and nuclear halogen-substituted products. However, other diphenols with a sulfur-containing core can also be used. for example, or

Diphenols having a sulfur-containing nucleus such as [Formula] and substituted products thereof can also be used as starting materials for producing sulfur-containing polyols. In some cases, 2, 2′,
Tri- to tetravalent polyphenols such as 4,4'-tetrahydroxydiphenyl sulfide can also be used as starting materials for the production. The sulfur-containing polyol is preferably a polyol obtained using the above polyphenol as a starting material, particularly a compound obtained using dihydroxydiphenyl sulfide and its substituted product as a starting material. Particularly preferred sulfur-containing polyols are monoepoxide adducts of the above-mentioned polyphenols, and hydrolysates of glycidyl ethers of the above-mentioned polyphenols or oligomers thereof. These two types of sulfur-containing polyols will be explained below. A sulfur-containing polyol can be obtained by adding a monoepoxide to a polyphenol. A monoepoxide is a compound having one three-membered cyclic ether group, and includes, for example, alkylene oxide and styrene oxide. The amount added is required to be equivalent or more to the polyphenol; for example, two or more molecules of monoepoxide are added to one molecule of diphenol. The number of alcoholic hydroxyl groups in the resulting adduct corresponds to the number of hydroxyl groups in the starting polyphenol, regardless of the amount of monoepoxide added. That is, diol can be obtained from diphenol, and tetraol can be obtained from tetraphenol. Two or more types of monoepoxides can be used, and in that case, a mixture of two or more types of monoepoxides may be added, or different monoepoxides may be added sequentially. As the monoepoxide, alkylene oxide having 2 to 4 carbon atoms is preferred, and ethylene oxide and propylene oxide are particularly preferred. When the monoepoxide is an alkylene oxide having 2 to ⁴ carbon atoms, the resulting sulfur ^- containing polyol is It is a compound represented by the following formula []. A[-(OR]-) _n OH] ₂ ...[] A is the above divalent residue, and R has 2 to 2 carbon atoms.
In the alkylene group of 4, m is an integer of 1 or more. −(
OR−) _n represents the statistical average. That is,
For example, m in one molecule is an integer, but in a mixture of compounds with different m, the average value of m is often not an integer. In addition, the addition of alkylene oxide is a sequential reaction, and it is difficult to obtain a compound in which m is strictly constant, and even if m is 1, it often contains compounds in which m is 2 or more. . Furthermore, -(OR-) _n is two or more types of -(OR-) with different R.
-) may also be included. Also, two -( in one molecule
OR−) _n may be different. As will be described later, it is not preferable for m to be too large. The preferred range of m is 1.0 to 5 on average, especially 1.0 to 3.
is suitable, most preferably about 1.0. Glycidyl ethers of polyphenols such as bisphenol A and their oligomers are typical epoxy resins. Further, glycidyl ether, which is an alkylene oxide adduct of polyphenol, is also known as an epoxy resin. Hydrolysates of these epoxy resins are known and are sometimes called phenoxy compounds. Other examples of the sulfur-containing polyol in the present invention are phenoxy compounds similar to the above-mentioned phenoxy compounds having a sulfur-containing nucleus, and monoepoxide adducts thereof. That is, a polyol obtained by converting the epoxy group of the above-mentioned polyphenol containing a sulfur-containing nucleus or a glycidyl ether of its monoepoxide adduct or an oligomer of the glycidyl ether into two hydroxyl groups, and a monomer of the polyphenol. Epoxide adducts are one of the preferred sulfur-containing polyols in the present invention. For example, a more preferable example of such a sulfur-containing polyol is the following formula []
These are the compound represented by and its alkylene oxide adduct. B is a divalent residue of the same diphenol as A, except for its two hydroxyl groups, or a divalent residue of a diol represented by the formula [], except for its two hydroxyl groups. n is an integer of 0 or 1 or more. The alkylene oxide adduct of the compound represented by the formula [] is a compound in which part or all of the alcoholic hydroxyl groups of this compound have been converted to -(OR-) _n OH. As in the above formula [], n represents a statistical average, and for example, the average n may be less than 1. Preferred n is about 0-5, especially about 0-3. More preferred among the compounds represented by formula [] is one in which B is a residue of the diphenol represented by A above. In the compounds represented by formula [] and formula [], the diphenol residue represented by A is a lower alkyl group in which R ¹ and R ² are the same or different, respectively, among the polyvalent residues represented by formula []. Or a halogen atom, where k and l are each 0 or 1
and is preferably a diphenyl sulfide group. That is, A is preferably a divalent diphenyl sulfide group, a lower alkyl substituted product thereof, or a halogen substituted product thereof. Lower alkyl group has 4 carbon atoms
The following alkyl groups are particularly preferred, and a methyl group is particularly preferred. The halogen is chlorine or bromine, and chlorine is preferred from the viewpoint of weather resistance. It is preferable that each bond is located at a distal position relative to the sulfur atom bonding position. Particularly preferred A is a divalent diphenyl sulfide group having a bond at the rose position, that is, the sulfur-containing polyol is a derivative of 44'-dihydroxydiphenyl sulfide. The sulfur-containing polyol in the present invention is not limited to the representative compounds represented by the above formulas [] and []. For example, there are compounds represented by the following formula [] other than those represented by both formulas. A is the divalent residue described above. A[ ^-OR3- (OHP _{] 2} ...[] ^R3 : p+monovalent aliphatic or alicyclic residue p: an integer greater than or equal to 1 p is preferably 1, and ^R3 is cycloalkylene or an alkylene group having 8 or less carbon atoms.Furthermore, other sulfur-containing polyols include alkylene oxide adducts of 4,4'-diaminodiphenyl sulfide.Most preferred sulfur-containing polyols Specific examples are listed below, but the sulfur-containing polyol in the present invention is not limited to the following: Bis-[4-(hydroxyethoxy)phenyl sulfide, Bis-[4-(2- hydroxypropoxy)phenyl] sulfide, bis-[4-(2,3-dihydroxypropoxy)phenyl] sulfide, bis-[4-(4-hydroxycyclohexyloxy)phenyl] sulfide, bis-[2-methyl-4-( (hydroxyethoxy)-6-butylphenyl] sulfide, and compounds in which ethylene oxide and/or propylene oxide having an average of 3 or less molecules per hydroxyl group are added to these compounds.The larger the molecular weight per hydroxyl group of the sulfur-containing polyol, the more the obtained polyurethane. The hardness of synthetic resins tends to decrease and become more flexible.Therefore, unless flexibility is particularly required, the lower the molecular weight per hydroxyl group, the better.As a factor indicating the degree of molecular weight per hydroxyl group, The hydroxyl value is proportional to the reciprocal of the molecular weight per hydroxyl group.
That is, the lower the hydroxyl value, the higher the molecular weight per hydroxyl group. The hydroxyl value of the sulfur-containing polyol in the present invention is preferably about 100 or more, particularly preferably about 150 to 800. However, even if it is a sulfur-containing polyol with a lower hydroxyl value, it can be combined with an active hydrogen-containing compound having a lower molecular weight per active hydrogen atom, which will be described later, to lower the average molecular weight of both to produce a harder polyurethane synthetic resin. Therefore, the hydroxyl value is not necessarily limited to the above range. It goes without saying that two or more types of sulfur-containing polyols can be used in combination in the present invention. The sulfur-containing polyol can be used alone as a polyethylene synthetic resin. However, it can be used as a polyvalent active hydrogen-containing compound such as other polyols or polyamines. The polyvalent active hydrogen-containing compound is a compound having at least two functional groups having active hydrogen atoms reactive with isocyanate groups such as alcoholic hydroxyl groups, amino groups, or imino groups. The preferred polyhydric active hydrogen-containing compound is a polyol, but known compounds other than polyols, known in the art of polyurethane chemistry as chain extenders or crosslinkers, may be used, particularly polyamines such as diamines. Various compounds can be used as polyols. In particular, polyols having a relatively low average molecular weight per hydroxyl group are preferred. The average molecular weight per hydroxyl group is not particularly limited, but is preferably about 500 or less, particularly about 200 or less. The hardness of the polyurethane synthetic resin tends to increase as the average molecular weight per hydroxyl group in the total of these polyols and the sulfur-containing polyol is lower, provided that the polyisocyanate compound remains the same. Therefore, in order to obtain a hard polyurethane synthetic resin, the average molecular weight per hydroxyl group of the polyol used in combination with the sulfur-containing polyol must be approximately equal to or lower than the average molecular weight per hydroxyl group of the sulfur-containing polyol. preferable. Further, the number of hydroxyl groups in the polyol is suitably 2 to 8, particularly preferably 2 to 4. The proportion of the sulfur-containing polyol needs to be within the range of about 10 to 100% by weight, more preferably about 30 to 100% by weight, based on the total of the sulfur-containing polyol and the polyvalent active hydrogen-containing compound. be. Moreover, from the viewpoint of refractive index, about 60 to 100% by weight is particularly preferable. Note that when a polyvalent active hydrogen-containing compound is used in combination with a sulfur-containing polyol, it is not necessarily necessary to mix the two together. For example, in the case of production by the prepolymer method, a prepolymer is produced from a sulfur-containing polyol and a non-yellowing polyisocyanate compound, and this prepolymer is cured with a polyvalent active hydrogen-containing compound to produce a polyurethane synthetic resin. be able to. Examples of the polyols that can be used in combination include polyhydric alcohols, poly(oxyalkylene) diols, other polyether polyols, polyester polyols, and other polyols. Examples of polyhydric alcohols include ethylene glycol, propylene glycol, butylene glycol, 1,4
-butanediol, neopentyglycol, glycerin, trimethylolpropane, 1,4-cyclohexanediol, tricyclo[5,2,1,
0 ^2.6 ] Decane dimethanol, 1,2,6-cyclohexanetriol, dipromoneopentyl glycol, etc. Examples of poly(oxyalkylene) diols include diethylene glycol, triethylene glycol, tetraethylene glycol, dipropylene glycol, and tripropylene glycol. Examples of polyether polyols include the above-mentioned polyhydric alcohols, poly(oxyalkylene glycols), polyhydric phenols (e.g. bisphenol A), alkanolamines,
There are compounds obtained by adding the above-mentioned monoepoxides (especially ethylene oxide and propylene oxide) such as polyamines. Examples of polyester polyols include polyester polyols having residues of adipic acid, phthalic acid, isophthalic acid, and other polyhydric carboxylic acids and polyhydric alcohol residues as described above. Of course, two or more of these polyols can also be used in combination. The polyisocyanate compound can be roughly divided into non-yellowing polyisocyanate and yellowing polyisocyanate. As mentioned above, the polyisocyanate compound in the present invention is preferably non-yellowing polyisocyanate. A non-yellowing polyisocyanate is a polyisocyanate compound that does not contain an isocyanate group directly bonded to an aromatic nucleus, and as described below, there may be a compound having an aromatic nucleus. Yellowing polyisocyanates are aromatic polyisocyanate compounds containing isocyanate groups directly bonded to aromatic nuclei. As mentioned above, aromatic nuclei are effective in improving the refractive index of polyurethane synthetic resins. Therefore, the polyisocyanate compound is preferably a compound having an aromatic nucleus. On the other hand, yellowing polyisocyanates tend to yellow due to ultraviolet rays and the like, making them difficult to use for optical elements exposed to ultraviolet rays. Therefore, preferred polyisocyanate compounds are non-yellowing polyisocyanates having aromatic nuclei. Examples of the non-yellowing polyisocyanate having an aromatic nucleus include xylylene diisocyanate and tetramethylxylylene diisocyanate. Non-yellowing polyisocyanates without aromatic nuclei include aliphatic polyisocyanates and alicyclic polyisocyanates, such as hexamethylene diisocyanate, 2,2,4-trimethylhexamethylene diisocyanate, isophorone diisocyanate, dicyclohexylmethyl diisocyanate, bis( Examples include methyl isocyanate) cyclohexane. Furthermore, yellowing polyisocyanates that may be used in some cases include tolylene diisocyanate, diphenylmethane diisocyanate, polymethylene polyphenyl isocyanate, and naphthalene diisocyanate.
The polyisocyanate compound may also be a modified polyisocyanate as described above, such as a prepolymer type modified product, a carbodiimide modified product, a urea modified product, a Biuret modified product, an isocyanurate modified product, etc. Two or more of these polyisocyanate compounds can also be used in combination.
When a sulfur-containing polyol and the polyvalent active hydrogen compound are used together, the appropriate amount of the polyisocyanate compound to be used is about 0.9 to 1.2 equivalents based on the total equivalent of the sulfur-containing polyol and the sulfur-containing polyol.
Particularly preferred is about 0.95 to 1.1 equivalents. The polyurethane synthetic resin in the present invention is produced using various auxiliary raw materials in addition to the above-mentioned main raw materials. One of the auxiliary raw materials is a catalyst. Although a catalyst may not be particularly required when the reaction is allowed to proceed gradually, such as in the casting method described below, in many cases a catalyst is used to accelerate the polyurethane forming reaction. As the catalyst, those known in the field of polyurethane chemistry can be used, and representative catalysts include tertiary amine catalysts and organometallic compound catalysts. Examples of the former include triethylenediamine, triethylamine, and N-methylmorpholine, and examples of the latter include diptyltin dilaurate, stannath octoate, and other organotin compounds. Other auxiliary raw materials include, for example, stabilizers such as ultraviolet absorbers, light stabilizers, and antioxidants, and anti-coloring agents, which may be used in combination with the main raw material if necessary. Further, a coloring agent such as a dye may be added to the eyeglass lens. Of course, dyeing can be carried out after the spectacle lens is molded as is commonly done. The manufacturing method and molding method of the polyurethane synthetic resin are not particularly limited. The polyurethane synthetic resins used in the present invention can be roughly divided into those that have thermoplasticity and those that do not have thermoplasticity (hereinafter referred to as thermosetting).
There are two types. The former thermoplastic polyurethane synthetic resin is obtained using substantially divalent raw materials. That is, when a sulfur-containing diol, a non-yellowing diisocyanate compound, and a polyvalent active hydrogen compound are used together, a divalent compound (e.g.
It is obtained by reacting diols such as alcohols. However, a small amount of polyurethane from which trivalent or higher valent compounds can be obtained as a small portion of the raw materials may be used in combination so long as the thermoplasticity is not lost. Thermosetting polyurethane synthetic resins are obtained by using trivalent or higher valent compounds as part of the raw materials. Compounds with a valence of 3 or more are 2
For example, a combination of a tetravalent sulfur-containing polyol and a divalent sulfur-containing polyol, or a combination of a divalent sulfur-containing polyol and a polyol other than a trivalent or higher sulfur-containing polyol. A thermosetting polyurethane synthetic resin can also be obtained by such methods. However, thermosetting polyurethane synthetic resin is a term commonly used in the field of polyurethane chemistry, and refers to a three-dimensional network polymer that does not necessarily require curing with heat. Molding methods that can be commonly applied to thermoplastic polyurethane synthetic resins and thermosetting polyurethane synthetic resins are cast molding and RIM molding.
The cast molding method is a method in which the raw material mixture is injected into a predetermined mold and then heated, etc. to harden it and mold it. Although it is inferior to the RIM method and the injection molding method described below in terms of productivity, it does reduce molding distortion. A molded article with good optical properties can be obtained. The RIM method, ie, the reaction injection molding method, is a highly productive method in which raw materials separated into two or more components are mixed at high speed by a method such as collision mixing, and then injected into a mold and cured. On the other hand, in the case of thermoplastic polyurethane synthetic resin, secondary molding methods such as injection molding methods can be applied. For example, molding can be carried out by injection molding using granular or powder molding materials of thermoplastic polyurethane synthetic resin obtained by various methods. The injection molding method is a highly productive method and
There are fewer restrictions such as molding conditions than the RIM molding method.
The molding method for optical elements is not limited to these methods; for example, optical elements can be manufactured by cutting blocks or sheets of polyurethane synthetic resin, and in the case of thermoplastic polyurethane synthetic resin, pressing methods can also be applied. It is possible. In addition to the molding method, various methods for forming polyurethane from raw materials can be employed, such as a one-shot method, a prepolymer method, and a quasi-prepolymer method. Lenses are particularly suitable as the optical element of the present invention, including spherical lenses, aspheric lenses, irregular lenses, Fresnel lenses, and the like. Although it is particularly preferable to use it for eyeglasses, it can also be used for various optical devices as described above. Further, the optical element is not limited to a lens, but may be a diffraction grating, a prism, or other elements. EXAMPLES The present invention will be specifically explained below with reference to Examples, but the present invention is not limited to these Examples. The physical properties were measured using the following method. Refractive index: refractive index for light with a wavelength of 589.3 nm at 20°C YI: Yellow index (represents the degree of coloring). Color computer SM2 manufactured by Suga Test Instruments Co., Ltd.
Measurements by type. Haze: (represents the degree of transparency) Suga Test Instruments Co., Ltd.
Values measured by a manufactured haze meter. Example 1 Bis-(4-(hydroxyethoxy)phenyl)
306 parts of sulfide (parts by weight, same hereinafter), 188 parts of xylylene diisocyanate, 2 parts of dibutyltin dilaurate, and 4000 parts of chlorobenzene were placed in a four-necked flask equipped with a reflux condenser and a stirrer, and the mixture was heated in a nitrogen stream. 1 hour at 80°C and 130°C
Heated at ℃ for 4 hours. After the reaction was completed, the contents were poured into a large amount of methanol, and the resulting precipitate was reprecipitated with a dimethylformamide-methanol mixture, resulting in a molecular weight of approximately 240,000 (styrene equivalent value by GPC).
407 parts of a white thermoplastic polyurethane synthetic resin was obtained. By injection molding this synthetic resin, the outer diameter is
When molded into a 55 mm lens, a highly transparent lens with physical properties shown in Table 1 and a high refractive index with little coloring was obtained. Example 2 75 parts of a diol with a hydroxyl value of 286 consisting of a propylene oxide adduct of 4,4'-thiodiphenol,
Bis-[4-(2,3-dihydroxypropoxy)
After adding 36 parts of phenyl sulfide, 85 parts of isophorone diisocyanate, and diptyltin dilaurate in an amount of 100 ppm based on the above total amount and mixing with heat, two glass lens molds whose surfaces had been treated with a release agent in advance and fluorine were added. A resin gasket was injected into the assembled mold. It was then cured by heating at 80°C for 4 hours and then at 100°C for 48 hours in a hot air oven. Table 1 shows the properties of the obtained lens. Example 3 180 parts of bis-[4-(2,3-dihydroxypropoxy)phenyl]sulfide, 20 parts of tricyclo[5,2,1,0 ^2.6 ]decane dimethanol, 265 parts of tetramethylxylylene diisocyanate,
and dibutyltin dilaurate 100ppm,
A lens was manufactured in the same manner as in Example 2. The physical properties are shown in Table 1. Example 4 Bis-[4-(hydroxyethoxy)phenyl]
Highly branched polyester polyol with 300 parts of sulfide and hydroxyl value of 275 (Kemitsusier, Uekel, Hüls, trade name "Oxypolyester V-2922")
100 parts, 272 parts dicyclohexylmethane diisocyanate, and 100 ppm dibutyltin dilaunate
A lens was manufactured using the same method as in Example 2. The physical properties are shown in Table 1. Example 5 Bis-[4-(hydroxyethoxy)phenyl]
306 parts of sulfide, 204 parts of hydroxypivalic acid-neopentyl glycol ester diol with a hydroxyl value of 549 (BASF Japan, trade name "HPN"),
A lens was manufactured in the same manner as in Example 2 using 444 parts of isophorone diisocyanate and 100 ppm of dibutyltin dilaurate. The physical properties are shown in Table 1. Example 6 33.4 parts of bis-[4-(2-hydroxypropoxy)phenyl]sulfide, bis-[4-(2,3-
dihydroxypropoxy) phenyl] sulfide
36.6 parts of 4,4'-diphenylmethane diisocyanate and 75 parts of dibutyltin dilaurate were added to the above total amount to 50 ppm, heated and mixed, poured into the same mold as in Example 2,
It was heat cured at 120°C for 6 hours and 48 hours at 120°C. Table 1 shows the physical properties of the obtained lens. Example 7 Epoxy oxygen content obtained by reaction of 4,4'thiodiphenol and epichlorohydrin
Hydrolyze 8.95% epoxy resin to reduce hydroxyl value
583 polyol compounds were obtained. A lens was obtained in the same manner as in Example 2 using 100 parts of this polyol compound, 127 parts of tetramethylxylylene diisocyanate, and 120 ppm of dibutyltin dilaurate. The physical properties are shown in Table 1. Example 8 Example 2 was prepared using 375 parts of bis-[5-chloro-2-(hydroxyethoxy)phenyl]sulfide, 244 parts of tetramethylxylylene diisocyanate, and 200 ppm of dibutyltin dilaurate.
A lens was obtained in the same manner as above. The physical properties are shown in Table 1. Comparative Example 1 Example 1 was repeated except that the bis-[4-hydroxyethoxyphenyl] sulfide in Example 1 was replaced with 316 parts of 2,2'-bis-[4-hydroxyethoxyphenyl]propane. The refractive index of the obtained lens was only 1.574, which was significantly lower than 1.608 when a sulfur-containing compound was used. Comparative Example 2 100 parts of 2,2'-bis-(4-allyloxycarbonyloxyethoxy-2,3,5,6-tetrabromophenyl)propane and 3.5 parts of diisopropyl peroxydicarbonate were mixed, Glass lens mold and fluororesin gasket twisted together

[Table] Example 9 Weather resistance test of lenses of Examples 1, 2, 3, 4 and Comparative Example 2 (Sunshine Weather-Ometer 240
The measured YI values and color changes (ΔY.I.) after the time exposure test are shown in Table 2.

【table】

Claims (1)

[Scope of Claims] 1 A sulfur-containing polyol containing a divalent or higher residue represented by the following formula [] and two or more alcoholic hydroxyl groups, or a proportion of the sulfur-containing polyol at least 10% by weight. An optical element made of a polyurethane synthetic resin obtained by reacting a combination of the sulfur-containing polyol and another polyvalent active hydrogen-containing compound with a polyisocyanate compound. However, R ¹ , R ² : Same or different lower alkyl group, halogen atom, or bond k, l: 0, 1, or 2 2 sulfur-containing polyol is a sulfur-containing diol represented by the following formula [] The optical element according to claim 1, characterized in that: A [-(OR]-) _n OH] ₂ ... [] A: Divalent residue represented by the formula [] R: Alkylene group having 2 to 4 carbon atoms m: An integer of 1 or more 3 Sulfur-containing polyol The optical element according to claim 1, wherein is a sulfur-containing polyol represented by the following formula []. B: A divalent residue represented by the formula [], or a residue obtained by removing two hydroxyl groups of a sulfur-containing diol represented by the formula [] n: an integer of 0 or 1 or more