JPH0353329B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention relates to an optical element, and particularly to an optical element having excellent light resistance, a refractive index of 1.51 to 1.53, and an Abbe number of 50 or more. [Conventional technology] Inorganic glass has traditionally been used for many purposes due to its excellent transparency, hardness, scratch resistance, weather resistance, etc. However, on the other hand, it is brittle, easily broken, and heavy. It has the following drawbacks. On the other hand, organic glass has advantages that inorganic glass does not have, such as lightness, safety, processability, and dyeability, and currently polymers of polymethyl methacrylate, polycarbonate, and diethylene glycol bisallyl carbonate are being used. There is. Particularly in applications such as eyeglass lenses, there are extremely high expectations for organic glass due to its lightness and safety (resistance to breakage). However, diethylene glycol diallyl carbonate polymer has a low refractive index (refractive index
1.499), which has the disadvantage of being thicker than inorganic glass lenses. In order to improve this drawback, attempts have been made to use resins with a high refractive index. However, polystyrene (refractive index 1.59), polycarbonate (refractive index 1.59), etc., which have a high refractive index, are thermoplastic resins and are mainly molded by injection molding, so they tend to retain distortion during molding and have poor solvent resistance. It has the disadvantage of being inferior. As a method to overcome the drawbacks associated with these molding materials and molding methods, a composition containing a monomer having an aromatic ring and/or a halogen as a molecular structural unit is cast-polymerized to produce a material with a high refractive index. A method of obtaining the resin has been proposed. Examples of these include JP-A-57-28115 and JP-A-57-28116.
No. 59-184210, No. 60-7314, No. 60-179406, No. 60-217301,
No. 60-186514, No. 60-166307, No. 60
-103301 publication etc. However, the high refractive index resins obtained by these methods have the disadvantage that they have poor light resistance and are colored yellow to brown by sunlight when exposed outdoors for a long time. This drawback impairs its commercial value in applications that require non-tinting properties, such as eyeglass lenses. Furthermore, if the deterioration is severe, cracks may appear on the resin surface, clouding, whitening, etc. may occur. This drawback can be improved to some extent by adding ultraviolet absorbers, antioxidants, etc., but compared to monomers that do not contain aromatic rings and/or halogens as molecular structural units, such as diethylene glycol bisallyl carbonate polymers. If so, the light resistance is still poor. In addition, if the amount of these additives added is large, not only will the quality of the optical element be impaired due to leakage or coloring of the additive from the polymer, but also the secondary coating such as hard coat treatment or multi-coat treatment It also causes poor adhesion during processing. Furthermore, as another method for increasing the refractive index, attempts have been made to introduce sulfur compounds as molecular structural units. For example, JP-A-57-158213 discloses a high refractive index polymer containing a thioester of (meth)acrylic acid as a copolymer component. However, although the polymer obtained by this method has a high refractive index, it is a thermoplastic polymer and has the drawback of poor heat resistance and chemical resistance. In addition, those having a diphenyl sulfone structure (for example, JP-A-57-28118, JP-A-57-28118;
-147505, No. 61-108616), those having a diphenyl sulfide structure (for example, JP-A-60-26010), and those having a dibenzyl sulfide structure (for example, JP-A-59-164501). Public bulletin) etc. have been proposed. However, the monomers produced by these methods generally have low compatibility with other liquid monomers and many exhibit high melting points, so not only are there many difficulties in molding, but the resulting high refractive index resin is It has the drawback of poor light resistance and easy discoloration. On the other hand, aliphatic sulfide compounds have excellent light resistance, so for example, low-molecular sulfide compounds are used as oxidation stabilizers for resins, and high-molecular sulfide compounds are often used as sealants for window glass. . In addition, technology to radically polymerize polyene compounds/polythiol compounds using chemically active energy rays such as radical initiators or ultraviolet rays to form polymeric sulfide compounds, which can be used as printing materials, paints, adhesives, molding materials, etc. has been reported (Japanese Patent Publication No. 53-28959 and JP-A-57-125025). However, in these methods, (meta)
When a polyene compound made of an acrylic acid derivative is used, the composition made of a polyene compound/polythiol compound has high reactivity and has extremely poor storage stability. Since the radical addition reaction proceeds together, the mercapto group of the polythiol compound tends to remain. This undesirable reaction results in a decrease in crosslinking density during polymerization, causing new problems such as a decrease in hardness due to insufficient curing of the polymer, a decrease in solvent resistance, and a decrease in strength. In addition, due to the difference in reactivity between polyene compounds and polythiol compounds, as mentioned above, the refractive index changes rapidly in a minute range, especially in fields such as eyeglass lenses that require homogeneity and transparency. ” is likely to occur, and the optical properties or appearance are significantly impaired. Furthermore, such defects may cause malfunctions during recording and reading when used as an optical disk material, for example. As mentioned above, when a composition consisting of a polyene compound/polythiol compound is used as a polymerizable monomer composition for an optical material, storage stability is poor, and the problem of "polymerization spots" during polymerization cannot be solved. Ta. [Problems to be Solved by the Invention] As a result of intensive studies to solve the drawbacks of the above-mentioned prior art, the inventors conducted an addition reaction between a polyene compound and a polythiol compound in advance with an excess of the polyene compound in a basic manner. A liquid polymerizable prepolymer obtained by substantially eliminating the mercapto groups of a polythiol compound in an atmosphere, or a mixture of this prepolymer and a polymerizable aliphatic polyfunctional vinyl monomer, has good storage stability. There are, and optical elements made of these cured products are:
The present invention was achieved by finding that there were no polymerization spots. Therefore, an object of the present invention is to provide an optical element that is free from polymerization spots, has excellent light resistance, has a refractive index of 1.51 to 1.53, and has an Abbé number of 50 or more. [Means for Solving the Problems] The present invention provides an optical element that can achieve the above object. That is, the present invention provides the following: [A](1) General formula () (In the formula, R ¹ and R ² may be the same or different and represent H or CH ₃ group, and R ³ is a substituted or unsubstituted group that may contain an OH group having 2 to 20 carbon atoms. (represents an aliphatic polyhydric alcohol residue or a substituted or unsubstituted polyalkylene ether polyol residue, m represents an integer of 1 to 2), (2) a polyene compound represented by the general formula () R ⁴ − (SH) _p () (In the formula, R ⁴ represents a substituted or unsubstituted polyvalent aliphatic hydrocarbon residue which may contain an OH group having 2 to 20 carbon atoms, and p is a residue of 2 to 4 carbon atoms. Indicates an integer) Polythiol compound () and/or (3) General formula () (In the formula, R ⁵ represents a substituted or unsubstituted aliphatic polyhydric alcohol residue that may contain an OH group having 2 to 20 carbon atoms, q is an integer of 1 to 2, and r is an integer of 2 to 4. ) is preliminarily subjected to an addition reaction with a polythiol compound () represented by () in the presence of a base catalyst at a functional group equivalent ratio of the polyene compound () to the polythiol compound () and/or () in the range of 2 to 10. at least 50% by weight
The present invention relates to an optical element comprising a cured product of a mixture of a liquid polymerizable prepolymer and [B] a polymerizable aliphatic polyfunctional vinyl monomer having a refractive index of 1.45 or more at most 50% by weight. Representative examples of the poene compound () represented by the general formula () include ethylene glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate, and tetraethylene glycol di(meth)acrylate. , 2-hydroxypropyl-1,3-di(meth)acrylate, 1,
6-hexane di(meth)acrylate, neopentyl glycol di(meth)acrylate, pentaerythritol tri(meth)acrylate, trimethylolpropane tri(meth)acrylate,
Examples include dipentaerythritol hexa(meth)acrylate. Representative examples of the polythiol compound () represented by the general formula () include propane-1,2
-dithiol, n-hexane-1,6-dithiol, ethanedithiol, neopentane-1,3-
Examples include dithiol, propane-1,3-dithiol, and cyclohexane-1,4-dithiol. Further, as representative examples of the polythiol compound () represented by the general formula (), ethylene glycol dithioglycolate, diethylene glycol dithioglycolate, trimethylolpropane trithioglycolate, trimethylolpropane dithioglycolate, neopentyl glycol tetra Examples include thioglycolate, pentaerythritol tetrathioglycolate, and trimethylolpropane trithiopropionate. When manufacturing a liquid polymerizable prepolymer by addition-reacting a polyene compound () and a polythiol compound () and/or (), the polythiol compound () and/or
The functional group equivalent ratio for () is within the range of 2-10. When the functional group equivalent ratio is less than 2,
Not only does gelation often occur depending on the type and combination of compounds, but even if it is obtained as a liquid prepolymer, the cured product obtained by polymerizing it tends to have polymerization spots and has poor heat resistance. It has the disadvantage of being poor. On the other hand, when the functional group equivalent ratio exceeds 10, prepolymerization is easy, but the refractive index of the cured product obtained from the prepolymer is less than 1.51. The addition reaction between the polyene compound () and the polythiol compound () and/or () is carried out in the presence of a basic catalyst. As the basic catalyst, conventionally known basic ion exchange resins, potassium, t-butoxide, phosphine compounds, amine compounds, etc. can be used, but phosphine compounds or amine compounds are particularly preferred. Examples of phosphine compounds include triphenylphosphine, tri-n-butylphosphine, triethylphosphine, and the like. In addition, examples of amine compounds include pyridine,
N,N-dimethylaniline, N,N-diethylaniline, trimethylamine, triethylamine,
Tri(n-propyl)amine, tri(iso-propyl)amine, tri(n-butyl)amine, tri(iso-butyl)amine, tri(sec-butyl)amine, dimethylethylamine, diethylmethylamine, triethanolamine , dimethylethanolamine, monomethyldiethanolamine, diethylamine, etc. These basic catalysts may be used alone or in combination, and the amount used varies depending on the type, combination, and amount of the polyene compound () and polythiol compound () and/or () used, so it cannot be generalized. Although it cannot be specified, it is 0.01 to 3% by weight, preferably 0.03 to 1% by weight, based on the total amount of the polyene compound () and the polythiol compound () and/or (). When the amount of the basic catalyst used is less than 0.01% by weight, the catalyst does not substantially function, and homopolymerization of the vinyl groups of the polyene compound () often occurs. on the other hand,
Even if it is used in an amount exceeding 3% by weight, not only the effect of using a large amount is not observed, but also coloring occurs during polymerization, which is not preferable. Furthermore, even if the catalyst is removed after the reaction, a large amount of removal agent is required, which is rather undesirable. During the addition reaction of the polyene compound () and the polythiol compound () and/or (), an inert solvent with a low boiling point, such as benzene, tetrahydrofuran, etc., may be used as necessary to remove the reaction heat.
Dioxane, ether, etc. can also be used in appropriate amounts. If it is necessary to remove the basic catalyst after the addition reaction, known methods such as adsorption, extraction, vacuum suction, etc. can be applied within a range that does not affect the next step of polymerization. In particular, for the removal of amine compounds, adsorption removal methods using neutral, acidic alumina, and acidic ion exchange resins can be applied, and in the case of amine compounds with low boiling points, removal methods using vacuum suction can also be applied. can be used. The temperature at which the addition reaction is carried out cannot be unconditionally defined because it varies depending on the combination of the polyene compound () and the polythiol compound () and/or (), the blending ratio, or the type and amount of the basic catalyst used. Usually 0-100℃, preferably
The temperature is 20-60℃. Even if the addition reaction temperature exceeds 100°C, depending on the type and amount of the basic catalyst used, homopolymerization of the vinyl group of the polyene compound () may be prevented in some cases, but this is not preferable because gelation often occurs. . On the other hand, although the addition reaction proceeds at temperatures below 0°C, the reaction rate is slow and unfavorable in terms of production. During the addition reaction, the addition reaction is preferably carried out in an inert atmosphere in order to prevent the formation of disulfide due to autooxidation of the polythiol compound () and/or (). The liquid polymerizable prepolymer thus obtained is
It has a structure in which the molecular end is capped with a polymerizable vinyl group, and has excellent storage stability. moreover,
This prepolymer has a viscosity of 50 to 2000 centipoise, and may contain unreacted polyene compound depending on the molar ratio of polyene compound and polythiol compound. This unreacted polyene compound may be removed if necessary, or may be used as is. The optical element of the present invention may be composed of a cured product of the liquid polymerizable prepolymer alone, but as long as the purpose of the present invention is not unduly hindered, the optical element may be composed of the cured product of the liquid polymerizable prepolymer alone. It may be made of a cured product of a mixture of polymerizable aliphatic polyfunctional vinyl monomers having a refractive index of 1.45 or more. Examples of polymerizable aliphatic polyfunctional vinyl monomers with a refractive index of 1.45 or higher include ethylene glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate, and tetraethylene glycol di(meth)acrylate. , 2-hydroxypropyl-1,3-di(meth)acrylate, 1,
Examples include 6-hexane di(meth)acrylate, neopentyl glycol di(meth)acrylate, pentaerythritol tri(meth)acrylate, and trimethylolpropane tri(meth)acrylate. If the refractive index of the polymerizable aliphatic polyfunctional vinyl monomer is less than 1.45, the refractive index of the cured product will be low, which is not preferable. The ratio of the liquid polymerizable prepolymer to the polymerizable aliphatic polyfunctional vinyl monomer is at least 50% by weight of the liquid polymerizable prepolymer and at most 50% by weight of the polymerizable aliphatic polyfunctional vinyl monomer. If the proportion of the polymerizable aliphatic polyfunctional vinyl monomer is more than 50% by weight, the refractive index of the cured product will be low, and the shrinkage during polymerization will be large, resulting in a cured product with a good appearance without cracks or cracks. Things become difficult. The liquid polymerizable prepolymer or the mixture of the liquid polymerizable prepolymer and the polymerizable aliphatic polyfunctional vinyl monomer can be cured by radical polymerization. As the polymerization method, not only thermal polymerization but also a polymerization method using active energy rays such as ultraviolet rays and γ rays can be used. Moreover, the above methods can be used not only alone but also in combination. When carrying out thermal polymerization, benzoyl peroxide, diisopropyl peroxydicarbonate, azobisisobutyronitrile, azodicyclohexanecarbonitrile, tert-butyl peroxy-
Common radical polymerization initiators such as 2-ethylhexanoate, azobismethylvaleronitrile, or mixtures thereof can be used. In the case of ultraviolet curing, generally known benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin propyl ether, benzoin isobutyl ether, 2-hydroxy-2-benzoyl-propane, benzyl,
Photosensitizers such as thioxanthone and diphenyl disulfide can be used. These radical polymerization initiators or photosensitizers are used in an amount of about 5% by weight at most with respect to the liquid polymerizable prepolymer or the mixture of the liquid polymerizable prepolymer and the polymerizable aliphatic polyfunctional vinyl monomer. It will be done. Furthermore, when using radiation such as gamma rays, it is generally not necessary to use a polymerization initiator. In addition, if necessary, an anti-yellowing agent, a leveling agent, or an ultraviolet absorber may be added to the liquid polymerizable prepolymer or the mixture of the liquid polymerizable prepolymer and the polymerizable aliphatic polyfunctional vinyl monomer so as not to interfere with polymerization and curing. It can be added within a range. The optical element according to the present invention is produced by a cast polymerization method. As the cast polymerization container, plate-shaped, lens-shaped, cylindrical, prismatic, conical, spherical, or other molds or molds designed according to the purpose are used. For example, to produce an optical lens, a liquid polymerizable prepolymer or a mixture of a liquid polymerizable prepolymer and a polymerizable aliphatic polyfunctional vinyl monomer is poured into a lens mold assembled from a glass mold and a gasket, heated, irradiation with ultraviolet light or other active energy radiation;
Alternatively, a combination of these methods may be used to remove the mold after curing. The optical element obtained in the present invention is used for optical reading, reproduction, and writing, for example, for so-called lenses for still cameras, video cameras, telescopes, glasses, etc., compact disks, video disks, etc. It refers to elements that function by transmitting or reflecting light, such as so-called optical disks and transparent sealing materials for sealing display elements such as liquid crystals. [Effects of the Invention] The liquid polymerizable prepolymer or the mixture of the liquid polymerizable prepolymer and the polymerizable aliphatic polyfunctional vinyl monomer according to the present invention has good storage stability, and optical fibers made of the cured product thereof have good storage stability. The device has no polymerization spots, has excellent light resistance, and has a refractive index of 1.51~
1.53 and has an Abbe number of 50 or more, which solves the problems of the conventional optical elements described above. [Example] Hereinafter, the present invention will be explained in more detail with reference to Examples. In addition, each physical property value of the cured product obtained in the Examples and Comparative Examples was measured by the following test method. (1) Polymerization spots The appearance of the cured product was visually observed using a 20W fluorescent lamp. × if there are spots, ○ if there are no spots
And so. (2) Refractive index The refractive index at 20°C was measured using an Atsube refractometer. Bromonaphthalin was used as the contact liquid. (3) Hardness Measured using a Barcall hardness meter. (4) Light transmittance Light transmittance (%) at 550 nm is shown for a flat plate of cured material with a thickness of 2 mm. (5) Impact resistance test Based on FDA standards, from a height of 127 cm at the center of a 2 mm thick cured flat plate, a diameter of 15.9 mm and weight.
A 16.2g steel ball was dropped and those that did not break were marked as ○, and the others were marked as ×. (6) Heat resistance After leaving it in a hot air dryer at 120℃ for 3 hours,
Those in which no coloration or surface distortion was observed by visual observation were rated as ○, and the others were rated as ×. (7) Dyeability Immerse the cured product in a 0.2% Disperse Brown 3 aqueous solution, soak it at 92℃ for 10 minutes, and then pull it out.
Wash thoroughly with water and dry. In this dyed and cured product, those in which no staining spots were observed were rated ○, and those in which some staining spots were observed were rated △. (8) Light resistance The yellowness index (YI) of a 2.2 mm thick test piece was measured (JISK-7103) using a color meter (Suga Test Instruments Manufacturing Co., Ltd.) after 200 hours of exposure using a weather-o-meter. If the increase from YI before exposure (△YI) is △YI < 1, mark it as ○.
The case of 1≦△Y<5 was marked as △, and the case of 5≦△YI was marked as ×. Reference Example 1 After charging 750 parts by weight of ethylene glycol dimethacrylate at room temperature into a 2-separafluid flask equipped with a stirrer and a dropping funnel, 2 parts by weight of diethylamine
Parts by weight were added under stirring and dissolved. This is then added to ethylene glycol dithioglycolate 250
Parts by weight were added dropwise over 30 minutes. The mixture was stirred at room temperature until the heat generation stopped, and then stirred at 40°C for 10 hours. After the reaction, an inorganic adsorbent for strong base adsorption (Kyowa Kagaku Kogyo Co., Ltd., Kyoword 700SL) was added.
Diethylamine was removed by adding 50 parts by weight. The adsorbent was separated to obtain a liquid polymerizable prepolymer. ¹ H-NMR spectrum data of this liquid polymerizable prepolymer was obtained as follows. ¹ H-NMR: 1.2-1.35 (m, α-methylpton when β-methylene of methacryloyl is added to thiol),
1.9 to 2.03 (d, α-methyl proton of methacryloyl), 2.5 to 3.1 (m, methine proton and β-methylene proton next to α-methyl when β-methylene of methacryloyl is added to thiol),
3.23 to 3.33 (methylene proton next to thiol in ethylene dithiopropionate), 4.3 to 4.5 (proton on ethoxy in ethylene glycol dimethacrylate and ethylene dithiopropionate), 5.5
~6.2 (β-methylene proton of methacryloyl). Raman spectrum: Mercapto absorption at 1570 cm ^-1 disappeared. Furthermore, from the integral curve, the reaction rate of the vinyl group derived from methacryloyl was 34.8%, which was in good agreement with the theoretical reaction rate of 35.2% when 100% of the thiol group reacted. Furthermore, when the thiol groups in the liquid polymerizable prepolymer were determined by titration (Volhard method),
The reaction rate of thiol groups was 99.2%, and there were virtually no residual thiol groups. From the above results, it was clear that a liquid polymerizable prepolymer having a polythioether skeleton was obtained. Reference Examples 2 to 8 Addition reactions were carried out in the same manner as in Reference Example 1, except that the polyene compound, polythiol compound, basic catalyst, addition reaction temperature, and addition reaction time were set to the conditions shown in Table 1. The results are shown in Table 1. These results all suggested that liquid polymerizable prepolymers substantially having a polythioether skeleton were obtained. Comparative Reference Examples 1 to 3 An addition reaction was carried out in the same manner as in Reference Example 1, except that the conditions shown in Table 1 were used.

【table】

[Table] Regarding the storage stability, when the sample was left in a dark place at room temperature for one month, a sample in which no gel formation was observed was rated ○, and a sample in which gel formation was observed was rated x. As is clear from Table 1, the liquid polymerizable prepolymers obtained in Reference Examples 1 to 8 have excellent storage stability. Example 1 Liquid polymerizable prepolymer obtained in Reference Example 1
After mixing and dissolving 0.2 parts by weight of azobisisobutyronitrile in 100 parts by weight, the solution was poured into a mold consisting of an ethylene-vinyl acetate resin gasket and two glass plates, and heated at 30°C in a hot air oven. After heating at 35℃ for 2 hours and 10 hours at 80℃ for 8 hours.
The temperature rose to Thereafter, the gasket and mold were removed to obtain a cured product. 120% of the obtained cured product
When annealing was performed by heating at ℃ for 2 hours, a colorless and transparent cured product was obtained. Table 2 shows the physical property values of the cured product. Examples 2 to 8 and Comparative Examples 1 to 3 The prepolymers obtained in Reference Examples 2 to 7 and Comparative Reference Examples 1 to 3 were used, except that the amount of radical polymerization initiator shown in Table 2 was used. Polymerization was carried out in the same manner as in Example 1. Table 2 shows the physical property values of the obtained cured product.

[Table] Example 9 Using the apparatus of Reference Example 1, 660 parts by weight of ethylene glycol dimethacrylate and 340 parts by weight of ethylene glycol dithioglycolate were used (the functional group equivalent ratio of the polyene compound to the polythiol compound was 2). The rest was reacted in accordance with Reference Example 1 to obtain a polymerizable prepolymer having a viscosity of 600 centipoise. The reaction rate of thiol is
It was 99.3%. 50 parts by weight of this prepolymer, 40 parts by weight of caprolactone-modified polyfunctional polyacrylate (manufactured by Nippon Kayaku Co., Ltd., trade name DPCA-20), 2.
0.2 parts by weight of 2-azobis(2,4-dimethylvaleronitrile), 0.1 part of azobisisobutyronitrile
After mixing and dissolving parts by weight, the mixture was cured using the heating pattern described in Example 1, and a colorless and transparent cured product without polymerization spots was obtained. The physical properties of the cured product are Atsube number 54, refractive index 1.520, hardness 34, and light transmittance 91%.
It was hot. In addition, impact resistance, heat resistance, dyeability, and light resistance were all rated ○.

Claims (1)

[Claims] 1 [A] (1) General formula () (In the formula, R ¹ and R ² may be the same or different and represent H or CH ₃ group, and R ³ is a substituted or unsubstituted group that may contain an OH group having 2 to 20 carbon atoms. Represents an aliphatic polyhydric alcohol residue or a substituted or unsubstituted polyalkylene ether polyol residue, m represents an integer of 1 to 2.) A polyene compound represented by (), (2) General formula () R ⁴ -(SH) _p () (wherein, R ⁴ represents a substituted or unsubstituted polyvalent aliphatic hydrocarbon residue which may contain an OH group having 2 to 10 carbon atoms, and p is 2 to 4 (indicates an integer of ) Polythiol compound represented by () and/or (3) General formula () (In the formula, R ⁵ represents a substituted or unsubstituted aliphatic polyhydric alcohol residue that may contain an OH group having 2 to 20 carbon atoms, q is an integer of 1 to 2, and r is an integer of 2 to 4. ) is preliminarily subjected to an addition reaction with the polythiol compound () represented by () in the presence of a base catalyst in a range where the functional group equivalent ratio of the polyene compound () to the polythiol compound () and/or () is in the range of 2 to 10. get at least 50
An optical element comprising a cured product of a mixture of % by weight of a liquid polymerizable prepolymer and [B] at most 50% by weight of a polymerizable aliphatic polyfunctional vinyl monomer having a refractive index of 1.45 or more.