Patent Description:
It is known that a plastic lens with high refractive index can be obtained by reacting a polyisocyanate compound with a polythiol compound (see e.g. <CIT>). In <CIT>, a sulfur-containing urethane-based resin lens which is obtained by heating and curing a composition containing tetrathiol and at least one ester compound selected from a polyisocyanate compound, a polyisothiocyanate compound, and an isothiocyanate compound having an isocyanate group is disclosed. It is described that the lens is colorless and transparent and has a physical property of excellent heat resistance due to high refractive index and low dispersion and also excellent productivity.

<CIT> (<CIT>) discloses a polymerizable composition comprising (A) at least one isocyanate compound selected from di(isocyanatomethyl)-norbornane, -cyclohexane and -benzene, (B) a C<NUM>-<NUM>-aliphatic isocyanate compound; and (C) a thiol compound (C) which preferably is selected from specified compounds having <NUM>-<NUM> SH groups and <NUM>-<NUM> -S- bridges.

<CIT> (<CIT>) relates to a polymerizable composition comprising (A) a polythiol comprising a mixture of <NUM>,<NUM>-, <NUM>,<NUM>- and <NUM>,<NUM>-dimercaptomethyl-<NUM>,<NUM>-dimercapto-<NUM>,<NUM>,<NUM>-trithiaundecane; (B) a polyisocyanate selected from m-XDI, HMDI, isophorone diisocyanate and a mixture of <NUM>,<NUM>- and <NUM>,<NUM>-bis(isocyanatomethyl)-bicyclo[<NUM>. <NUM>]heptane; and (C) <NUM>-<NUM> wt. % of <NUM>-(<NUM>-hydroxy-<NUM>-t-butyl-<NUM>-methylphenyl)-chlorobenzotriazole as a UV-absorber.

<CIT> provides an internal release agent for optical materials made from polythiourethane resins, the release agent comprising (A) <NUM>-<NUM> wt. % of specified phosphoric acid monoesters (<NUM>) and (B) <NUM>-<NUM> wt. % of specified phosphoric acid diesters (<NUM>).

EP-A_2 <NUM><NUM> describes polythiourethane-based polymerizable composition comprising <NUM>-<NUM> pbw of a specified internal mold release agent, wherein the iso(thio)cyanates preferably are selected fromm-XDI, m-PDI, <NUM>,<NUM>- and <NUM>, <NUM>-tTDI, <NUM>,<NUM>-and <NUM>,<NUM>-bis(isocyanatomethyl)-bicyclo[<NUM>. <NUM>]-heptane, <NUM>,<NUM>- and <NUM>,<NUM>-bis(isocyanatomethyl)cyclohexane, and HMDI; and the active hydrogen compounds are preferably selected from specified compounds having <NUM>-<NUM> SH groups and optionally <NUM>-<NUM> -S- bridges.

<CIT> discloses a polymerizable composition comprising (A) at least one bi- or higher functional alicyclic polyisocyanate compound, (B) at least one polythiol of a general formula (<NUM>), (C) at least one thiol compound of a general formula (<NUM>) containing at least two SH groups and at least a -S- bridge, and (D) a specified polymerization catalyst.

However, the lens disclosed in <CIT> is problematic in that, as a cross-linked structure is formed at low temperature in order to use tetrathiol, viscosity increase is fast during the polymerization and striae are easily generated compared to other urethane resin-based plastic lenses.

Thus, an object of one example of the present invention is to provide a polymerizable composition allowing obtainment of an optical component with reduced striae, an optical component obtained from the polymerizable composition, a plastic lens containing the optical component, and a spectacle lens provided with a lens substrate formed of the optical component.

Furthermore, an object of one example of the present invention is to provide a polymerizable composition allowing obtainment of an optical component with excellent tensile strength, an optical component obtained from the polymerizable composition, a plastic lens containing the optical component, and a spectacle lens including a lens substrate including the optical component.

To solve the problems described above, the inventors of the present invention conducted intensive studies. As a result, it was found that, by using a polymerizable composition which contains an isocyanate component containing pre-determined alicyclic polyisocyanate and pre-determined non-cyclic aliphatic polyisocyanate and a polythiol component containing pre-determined polythiol, the above problems can be solved, and the present invention is completed accordingly.

Thus, the present invention provides a polymerizable composition (also referred to as "the present composition" herein) comprising an isocyanate component comprising alicyclic polyisocyanate (A-<NUM>)and non-cyclic aliphatic polyisocyanate (A-<NUM>); and a polythiol component comprising polythiol (B-<NUM>) and polythiol (B-<NUM>); wherein.

Furthermore, the invention provides (i) an optical component obtained by polymerizing the present composition, (ii) a plastic lens comprising said optical component and (iii) a spectacle lens comprising alens substrate which comprises said optical component.

According to the present invention, a polymerizable composition ("the present composition") allowing obtainment of an optical component with reduced striae, an optical component obtained from the polymerizable composition, a plastic lens containing the optical component, and a spectacle lens including a lens substrate including the optical component can be provided.

Also, according to the present invention, a polymerizable composition allowing obtainment of an optical component with excellent tensile strength, an optical component obtained from the polymerizable composition, a plastic lens containing the optical component, and a spectacle lens including a lens substrate including the optical component can be provided.

The present composition contains a specified isocyanate component which contains alicyclic polyisocyanate (A-<NUM>) having two isocyanate groups and non-cyclic aliphatic polyisocyanate (A-<NUM>) having two isocyanate groups, and a specified polythiol component which contains polythiol (B-<NUM>) having four mercapto groups and three sulfide bonds and polythiol (B-<NUM>) having two or three mercapto groups and two or three ester bonds.

The isocyanate component of the present composition contains the alicyclic polyisocyanate (A-<NUM>) having two isocyanate groups and the non-cyclic aliphatic polyisocyanate (A-<NUM>) having two isocyanate groups.

The alicyclic polyisocyanate (A-<NUM>) is at least one of isophorone diisocyanate, methylene biscyclohexyl diisocyanate, bis(isocyanatemethyl)cyclohexane, bis(isocyanatemethyl)bicyclo[<NUM>. <NUM>]heptane. These alicyclic polyisocyanates may be used either singly or in combinations or two or more types.

These alicyclic polyisocyanates (A-<NUM>) are suitable from the viewpoint of obtaining an optical component with reduced striae. From the viewpoint of improving further the tensile strength of an optical component which is produced by using the polymerizable composition, it is preferably at least one selected from isophorone diisocyanate, and bis(isocyanatemethyl)bicyclo[<NUM>. <NUM>]heptane.

The non-cyclic aliphatic polyisocyanate (A-<NUM>) is at least one of hexamethylene diisocyanate and trimethylhexamethylene diisocyanate. These polyisocyanates may be used either singly or in combinations or two or more types. They are suitable from the viewpoint of obtaining an optical component with reduced striae, and also from the viewpoint of improving the tensile strength of an optical component which is produced by using the polymerizable composition.

The isocyanate component of the present composition may contain, within a range in which the effect of the present invention is not impaired, polyisocyanate other than the alicyclic polyisocyanate (A-<NUM>) and the non-cyclic aliphatic polyisocyanate (A-<NUM>), if necessary.

The ratio of the total of the alicyclic polyisocyanate (A-<NUM>) and the non-cyclic aliphaticpolyisocyanate (A-<NUM>) in the isocyanate component of the present composition is, relative to the total mass of the isocyanate component, preferably ≥ <NUM> mass%, more preferably ≥ <NUM> mass%, even more preferably ≥ <NUM> mass%, and ≤ <NUM> mass%. As the ratio of the total of the alicyclic polyisocyanate (A-<NUM>) and the non-cyclic aliphatic polyisocyanate (A-<NUM>) is ≥ <NUM> mass%, the effect of suppressing striae of an optical component to be obtained can be further enhanced. Furthermore, it is also possible to improve the tensile strength of an optical component which is produced by using the present composition.

The molar ratio [(A-<NUM>)/(A-<NUM>)] between the alicyclic polyisocyanate (A-<NUM>) and the non-cyclic aliphatic polyisocyanate (A-<NUM>) is, from the viewpoint of further improving the effect of suppressing striae of an optical component to be obtained, preferably (<NUM>/<NUM>) - (<NUM>/<NUM>), more preferably (<NUM>/<NUM>) - ((<NUM>/<NUM>), and even more preferably (<NUM>/<NUM>) - (<NUM>/<NUM>). As the molar ratio is within the above range, the tensile strength of an optical component which is produced by using the present composition can be improved.

The polythiol component of the present composition contains the polythiol (B-<NUM>) having four mercapto groups and three sulfide bonds and the polythiol (B-<NUM>) having two or three mercapto groups and two or three ester bonds.

The polythiol (B-<NUM>) has four mercapto groups and three sulfide bonds, and is at least one of <NUM>,<NUM>-, <NUM>,<NUM>- and <NUM>,<NUM>-bis(mercaptomethyl)- <NUM>,<NUM>,<NUM>-trithiaundecane-<NUM>,<NUM>-dithiol. The polythiols (B-<NUM>) may be used either singly or in combinations or two or more types.

From the viewpoint of obtaining an optical component with high refractive index, heat resistance, and tensile strength, the polythiol (B-<NUM>) is preferably a mixture of <NUM>,<NUM>-, <NUM>,<NUM>- and <NUM>,<NUM>-bis(mercaptomethyl)-<NUM>,<NUM>,<NUM>-trithiaundecane-<NUM>,<NUM>-dithiol.

The polythiol (B-<NUM>) is at least one of trimethylol propane tris(thioglycolate), trimethylol propane tris(<NUM>-mercaptopropionate), <NUM>,<NUM>-butanediol bis(thioglycolate) and <NUM>,<NUM>-butanediol bis (<NUM>-mercaptopropionate). These polythiols may be used either singly or in combinations or two or more types.

The above polythiols (B-<NUM>) are suitable from the viewpoint of obtaining an optical component with reduced striae, and also from the viewpoint of improving further the tensile strength of an optical component which is produced by using the polymerizable composition.

It is preferable that the polythiol (B-<NUM>) has three mercapto groups. Accordingly, the heat resistance and tensile strength of an optical component which is produced by using the polymerizable composition of the present invention can be improved. In that case, the polythiol (B-<NUM>) is at least one of trimethylol propane tris(thioglycolate) and trimethylol propane tris(<NUM>-mercaptopropionate).

The polythiol component of the present composition may contain, within a range in which the effect of the present invention is not impaired, polythiol other than the polythiol (B-<NUM>) and the polythiol (B-<NUM>), if necessary.

From the viewpoint of obtaining an optical component with further reduced striae, the polymerizable composition which is more preferred among the polymerizable compositions of the present invention is as follows:.

The ratio of the total of the polythiol (B-<NUM>) and the polythiol (B-<NUM>) in the polythiol component of the present composition is, relative to the total mass of the polythiol component, preferably ≥ <NUM> mass%, more preferably ≥ <NUM> mass%, even more preferably ≥ <NUM> mass%, and ≤ <NUM> mass%. As the ratio of the total of the polythiol (B-<NUM>) and the polythiol (B-<NUM>) is ≥ <NUM> mass%, the effect of suppressing striae of an optical component to be obtained can be further enhanced. Furthermore, it is also possible to improve the tensile strength of an optical component which is produced by using the polymerizable composition of the present invention.

The molar ratio [(B-<NUM>)/(B-<NUM>)] between the polythiol (B-<NUM>) and the polythiol (B-<NUM>) is, from the viewpoint of further enhancing the effect of suppressing the striae of an optical component to be obtained, preferably (<NUM>/<NUM>)-(<NUM>/<NUM>), more preferably (<NUM>/<NUM>)-(<NUM>/<NUM>), and even more preferably (<NUM>/<NUM>)-(<NUM>/<NUM>). As the molar ratio [(B-<NUM>)/(B-<NUM>)] is within the above range, the tensile strength of an optical component which is produced by using the polymerizable composition can be improved.

The ratio between the polythiol component and the polyisocyanate component is, in terms of the functional group molar ratio between SH group and/NCO group, preferably within a range of <NUM>-<NUM>, more preferably <NUM>-<NUM>, even more preferably <NUM>-<NUM>, and even more preferably <NUM>-<NUM>.

It is also possible that the present composition consists of the above isocyanate component and the above polythiol component only. The content of the total of the isocyanate component and the polythiol component is preferably ≥ <NUM> mass%, more preferably ≥ <NUM> mass%, even more preferably ≥ <NUM> mass%, and even more preferably ≥ <NUM> mass% and ≤ <NUM> mass% in the polymerizable composition.

However, the present composition may contain, within a range in which the effect of the present invention is not impaired, a component which is different from the components of the above isocyanate component and the above polythiol component. Examples of such component include a compound which is copolymerizable with the above isocyanate component and the above polythiol component, an active hydrogen compound represented by amine, an epoxy compound, an olefin compound, a carbonate compound, an ester compound, a metal, a metal oxide, an organometallic compound, and an inorganic material. They may be used either singly or in combination of two or more types.

Furthermore, for control to desired reaction rate, a known reaction catalyst used for production of polythiourethane may be suitably added to the present composition. Examples of the reaction catalyst include organic tin like dimethyltindichloride. The blending amount of the reaction catalyst is, relative to the total amount of <NUM> parts by mass (pbm) of the isocyanate component and polythiol component, preferably <NUM>-<NUM> pbm, more preferably <NUM>-<NUM> pbm, and even more preferably <NUM>-<NUM> pbm.

A releasing agent may be also added. Examples of the releasing agent include a phosphoric acid-based releasing agent such as butoxy ethyl acid phosphate or dibutoxyethyl acid phosphate. The blending amount of the releasing agent is, relative to the total amount of <NUM> pbm of the isocyanate component and polythiol component, preferably <NUM>-<NUM> pbm, more preferably <NUM>-<NUM> pbm, and even more preferably <NUM>-<NUM> pbm.

Furthermore, depending on purpose, various materials including a chain extending agent, a cross-linking agent, a photostabilizer, a UV absorbing agent, an anti-oxidizing agent, an oil-soluble dye, a filler, a releasing agent, and a blueing agent may be added to the present composition.

The optical component of the present invention ("the present optical component") is obtained by polymerizing the present composition. The present optical component may be produced as described below, for example.

The method for producing an optical component includes a step of carrying out cast polymerization of the polymerizable composition. For example, the present composition is degassed, if necessary, and injected thereafter to a molding die. Then, the polymerizable composition injected to a molding die is polymerized. As for the molding die, a molding die consisting of a pair of glass mold or metal mold and a tape- or resin-based gasket is used. The polymerization time for polymerizing the polymerizable resin in a molding die is <NUM>-<NUM> hours, for example. The polymerization temperature is <NUM>-<NUM>, for example. To have a favorable release property of a transparent resin, which is prepared by polymerizing the polymerizable composition, from a molding die, it is also possible that a releasing agent is applied on releasing surface of a molding die or a releasing agent is added to the polymerizable composition. The optical component to be obtained accordingly has reduced striae, high index, lowdispersion, and low specific gravity. The optical component to be obtained also has excellent tensile strength. For such reasons, the present optical component is suitably used as an optical component of an optical device such as a spectacle lens or a camera lens.

The plastic lens of the present invention ("the present plastic lens") includes the present optical component, and is more preferably a lens including a lens substrate including the present optical component. The present plastic lens exhibits the effect of having reduced striae, high index, low dispersion, and low specific gravity. Furthermore, the present plastic lens has excellent tensile strength. The present plastic lens may consist of the present optical component only, or it may contain other optical component.

If necessary, an anti-reflection treatment or a surface polishing and dyeing treatment for having a fashion property or the like can be carried out for the present optical component. To have high hardness, improved abrasion resistance, improved chemical resistance, and an anti-fogging property, the spectacle lens may have at least one selected from an anti-static layer, a hard coating layer, an anti-reflection layer, and a light illuminating layer on top of the lens substrate consisting of the present optical component.

Hereinbelow, the present invention is further specifically explained by way of Examples.

For the plastic lenses of Examples and Comparative Examples, refractive index, Abbe number, heat resistance, striae, transparency, optical distortion, and tensile strength were evaluated.

By using precision refractometer KPR-<NUM> which is manufactured by Kalnew Optical Industrial Co. , the refractive index of plastic lens was measured at <NUM>° for the light with wavelength of F' ray (<NUM>), C' ray (<NUM>), and e ray (<NUM>). Then, by using the following formula, Abbe number was calculated. <MAT> ne represents the refractive index when measurement is made with a wavelength of e ray, nF' represents the refractive index when measurement is made with a wavelength of F' ray, and nC' represents the refractive index when measurement is made with a wavelength of C' ray.

According to a penetration method using TAS100TMAwhich is manufactured by Rigaku Corporation (thickness of test specimen: <NUM>, pin diameter: <NUM>, load: <NUM>, and temperature increase rate: <NUM>°/min), heat distortion temperature was measured.

The obtained plastic lens was observed with a naked eye according to Schlieren method, and striae of the plastic lens was evaluated based on the following three levels.

The plastic lens with evaluation result of VG or G has practically no problem in terms of striae. On the other hand, the plastic lens with the evaluation result of B is not suitable for practical use.

The obtained plastic lens was observed with a naked eye under a fluorescent lamp in dark room, and transparency of the plastic lens was evaluated based on the following three levels.

Those having no cloudiness and no precipitation of opaque materials: VG (Very Good).

Those observed with slight cloudiness or precipitation of opaque materials, or both of them: G (Good).

Those observed with cloudiness at strong level or clear precipitation of opaque materials: B (Bad).

The plastic lens with evaluation result of VG or G has practically no problem in terms of transparency. On the other hand, the plastic lens with the evaluation result of B is not suitable for practical use.

The obtained plastic lens was observed with a naked eye using a strain scope, and optical distortion of the plastic lens was evaluated based on the following three levels.

The plastic lens with evaluation result of VG or G has practically no problem in terms of optical distortion. On the other hand, the plastic lens with the evaluation result of B is not suitable for practical use.

By using a drill, a hole with <NUM> diameter was formed at <NUM> areas of a lens which has been adjusted to have <NUM> D, lens diameter of <NUM>, and thickness of <NUM>, and thus a sample was obtained. On Tensilon universal material tester manufactured by A&D Company, Limited (model number; RTC-1225A), both ends of the sample were fixed by using a pin with diameter of <NUM>. Then, elongation was made at rate of <NUM>/min, and the strength at break was measured.

The plastic lenses of the following Examples, Comparative Examples, and Reference Examples were produced as described below.

A mixture which has been obtained by sufficient mixing by stirring at room temperature of <NUM> pbm of isophorone diisocyanate (hereinbelow, described as "IPDI"), <NUM> pbm of a mixture of <NUM>, <NUM>-, <NUM>,<NUM>- and
<NUM>,<NUM>-bis(mercaptomethyl)-<NUM>,<NUM>,<NUM>-trithiaundecane-<NUM>,<NUM>-dithiol (" polythiol (B-<NUM>-<NUM>)"), <NUM> pbm of hexamethylene diisocyanate ("HDI"), <NUM> pbm of trimethylol propane tris(thioglycolate) ("TMTG"), <NUM> pbm of dimethyl tin dichloride, and <NUM> pbm of a mixture of butoxyethyl acid phosphate and dibutoxyethyl acid phosphate (manufactured by JOHOKU CHEMICAL CO. Productname: JP-<NUM>) was degassed under reduced pressure of <NUM> Pa (<NUM> mmHg) to prepare a homogeneously-prepared monomer mixture. The resulting monomer mixture was injected to a molding die which consists of a pair of glass molds and a gasket made of resin. Furthermore, as for the pair of glass molds, a pair with top mold curvature of <NUM> and bottom mold curvature of <NUM> was used, and thus the molding die was assembled such that the center thickness of a plastic lens becomes <NUM> and the diameter of a plastic lens becomes <NUM>.

After injecting the monomer mixture to the molding die, the temperature was raised from <NUM> to <NUM> over <NUM> hours followed by heat polymerization for <NUM> hours at <NUM>. After cooling, by extracting the plastic lens from the molding die, the plastic lens of Example <NUM> was obtained.

The plastic lens of Example <NUM> was produced by preparing a polymerizable composition in the same manner as Example <NUM> except that the blending amounts were modified to <NUM> pbm of IPDI, <NUM> pbm of the polythiol (B-<NUM>-<NUM>) , <NUM> pbm of HDI, and <NUM> pbm of TMTG.

The plastic lens of Example <NUM> was produced by preparing a polymerizable composition in the same manner as Example <NUM> except that the blending amounts were modified to <NUM> pbm of IPDI, <NUM> pbm of the polythiol (B-<NUM>-<NUM>), <NUM> pbm of HDI, and <NUM> pbm of TMTG.

The plastic lens of Example <NUM> was produced by preparing a polymerizable composition in the same manner as Example <NUM> except that the blending amounts were modified to <NUM> pbm of IPDI, <NUM> pbm of the polythiol (B-<NUM>-<NUM>) and <NUM> pbm of HDI, and <NUM> pbm of trimethylol propane tris (<NUM>-mercaptopropionate) ("TMTP") was used instead of TMTG.

The plastic lens of Example <NUM> was produced by preparing a polymerizable composition in the same manner as Example <NUM> except that the blending amounts were modified to <NUM> pbm of IPDI, <NUM> pbm of the polythiol (B-<NUM>-<NUM>) and <NUM> pbm of HDI, and <NUM> pbm of <NUM>,<NUM>-butanediol bis (mercaptoacetate) ("BDTG") was used instead of TMTG.

The plastic lens of Example <NUM> was produced by preparing a polymerizable composition in the same manner as Example <NUM> except that the blending amounts were modified to <NUM> pbm of IPDI, <NUM> pbm of the polythiol (B-<NUM>-<NUM>) and <NUM> pbm of HDI, and <NUM> pbm of <NUM>,<NUM>-butanediol bis (mercaptopropionate) ("BDTP") was used instead of TMTG.

The plastic lens of Example <NUM> was produced by preparing a polymerizable composition in the same manner as Example <NUM> except that the blending amounts were modified to <NUM> pbm of IPDI, <NUM> pbm of the polythiol (B-<NUM>-<NUM>) and <NUM> pbm of TMTG, and <NUM> pbm of trimethylhexamethylene diisocyanate ("TMDI") was used instead of HDI.

The plastic lens of Example <NUM> was produced by preparing a polymerizable composition in the same manner as Example <NUM> except that the blending amounts were modified to <NUM> pbm of IPDI and <NUM> pbm of the polythiol (B-<NUM>-<NUM>), and <NUM> pbm of TMDI was used instead of HDI, and <NUM> pbm of TMTP was used instead of TMTG.

The plastic lens of Example <NUM> was produced by preparing a polymerizable composition in the same manner as Example <NUM> except that the blending amounts were modified to <NUM> pbm of IPDI and <NUM> pbm of the polythiol (B-<NUM>-<NUM>), and <NUM> pbm of TMDI was used instead of HDI, and <NUM> pbm of BDTG was used instead of TMTG.

The plastic lens of Example <NUM> was produced by preparing a polymerizable composition in the same manner as Example <NUM> except that the blending amounts were modified to <NUM> pbm of IPDI and <NUM> pbm of the polythiol (B-<NUM>-<NUM>), and <NUM> pbm of TMDI was used instead of HDI, and <NUM> pbm of BDTP was used instead of TMTG.

The plastic lens of Example <NUM> was produced by preparing a polymerizable composition in the same manner as Example <NUM> except that <NUM> pbm of dicyclohexylmethane diisocyanate ("HMDI") was used instead of IPDI, and the blending amounts were modified to <NUM> pbm of the polythiol (B-<NUM>-<NUM>), <NUM> pbm of HDI and <NUM> pbm of TMTG.

The plastic lens of Example <NUM> was produced by preparing a polymerizable composition in the same manner as Example <NUM> except that the blending amounts were modified to <NUM> pbm of HMDI, <NUM> pbm of the polythiol (B-<NUM>-<NUM>) and <NUM> pbm of HDI, and <NUM> pbm of TMTP was used instead of TMTG.

The plastic lens of Example <NUM> was produced by preparing a polymerizable composition in the same manner as Example <NUM> except that the blending amounts were modified to <NUM> pbm of HMDI, <NUM> pbm of the polythiol (B-<NUM>-<NUM>) and <NUM> pbm of HDI, and <NUM> pbm of BDTP was used instead of TMTG.

The plastic lens of Example <NUM> was produced by preparing a polymerizable composition in the same manner as Example <NUM> except that the blending amounts were modified to <NUM> pbm of HMDI and <NUM> pbm of the polythiol (B-<NUM>-<NUM>), and <NUM> pbm of TMDI was used instead of HDI, and <NUM> pbm of TMTP was used instead of TMTG.

The plastic lens of Example <NUM> was produced by preparing a polymerizable composition in the same manner as Example <NUM> except that the blending amount s were modified to <NUM> pbm of HMDI and <NUM> pbm of the polythiol (B-<NUM>-<NUM>), and <NUM> pbm of TMDI was used instead of HDI, and <NUM> pbm of BDTG was used instead of TMTG.

The plastic lens of Example <NUM> was produced by preparing a polymerizable composition in the same manner as Example <NUM> except that <NUM> pbm of bis (isocyanatemethyl) cyclohexane ("HXDI") was used instead of IPDI, the blending amounts were modified to <NUM> pbm of the polythiol (B-<NUM>-<NUM>), and <NUM> pbm of HDI , and <NUM> pbm of TMTP was used instead of TMTG.

The plastic lens of Example <NUM> was produced by preparing a polymerizable composition in the same manner as Example <NUM> except that the blending amounts were modified to <NUM> pbm of HXDI, <NUM> pbm of the polythiol (B-<NUM>-<NUM>) and <NUM> pbm of HDI, and <NUM> pbm of BDTG was used instead of TMTP.

The plastic lens of Example <NUM> was produced by preparing a polymerizable composition in the same manner as Example <NUM> except that the blending amounts were modified to <NUM> pbm of HXDI and <NUM> pbm of the polythiol (B-<NUM>-<NUM>), and <NUM> pbm of TMDI was used instead of HDI, and <NUM> pbm of TMTG was used instead of TMTP.

The plastic lens of Example <NUM> was produced by preparing a polymerizable composition in the same manner as Example <NUM> except that the blending amounts were modified to <NUM> pbm of HXDI and <NUM> pbm of the polythiol (B-<NUM>-<NUM>), and <NUM> pbm of TMDI was used instead of HDI, and <NUM> pbm of BDTG was used instead of TMTP.

The plastic lens of Example <NUM> was produced by preparing a polymerizable composition in the same manner as Example <NUM> except that <NUM> pbm of bis(isocyanatemethyl)bicyclo[<NUM>. <NUM>]heptane ("NBDI") was used instead of IPDI, and the blending amounts were modified to <NUM> pbm of the polythiol (B-<NUM>-<NUM>), <NUM> pbm of HDI and <NUM> pbm of TMTG.

The plastic lens of Example <NUM> was produced by preparing a polymerizable composition in the same manner as Example <NUM> except that the blending amounts were modified to <NUM> pbm of NBDI, <NUM> pbm of the polythiol (B-<NUM>-<NUM>) and <NUM> pbm of HDI, and <NUM> pbm of BDTG was used instead of TMTG.

The plastic lens of Example <NUM> was produced by preparing a polymerizable composition in the same manner as Example <NUM> except that the blending amounts were modified to <NUM> pbm of NBDI and <NUM> pbm of the polythiol (B-<NUM>-<NUM>), and <NUM> pbm of TMDI was used instead of HDI, and <NUM> pbm of TMTP was used instead of TMTG.

The plastic lens of Example <NUM> was produced by preparing a polymerizable composition in the same manner as Example <NUM> except that the blending amounts were modified to <NUM> pbm of NBDI and <NUM> pbm of the polythiol (B-<NUM>-<NUM>), and <NUM> pbm of TMDI was used instead of HDI, and <NUM> pbm of BDTP was used instead of TMTG.

The plastic lens of Comparative Example <NUM> was produced by preparing a polymerizable composition in the same manner as Example <NUM> except that the blending amounts were modified to <NUM> pbm of HMDI and <NUM> pbm of the polythiol (B-<NUM>-<NUM>), and HDI and TMTG were not used.

The plastic lens of Comparative Example <NUM> was produced by preparing a polymerizable composition in the same manner as Example <NUM> except that the blending amounts were modified to <NUM> pbm of HMDI, <NUM> pbm of the polythiol (B-<NUM>-<NUM>) and <NUM> pbm of HDI, and TMTG was not used.

The plastic lens of Comparative Example <NUM> was produced by preparing a polymerizable composition in the same manner as Example <NUM> except that the blending amounts were modified to <NUM> pbm of HMDI and <NUM> pbm of the polythiol (B-<NUM>-<NUM>), <NUM> pbm of pentaerythritol tetrakis (mercaptopropionate) ("PTMP") was used instead of TMTG, and HDI was not used.

The plastic lens of Comparative Example <NUM> was produced by preparing a polymerizable composition in the same manner as Example <NUM> except that the blending amounts were modified to <NUM> pbm of HXDI and <NUM> pbm of the polythiol (B-<NUM>-<NUM>), and HDI and TMTG were not used.

The plastic lens of Comparative Example <NUM> was produced by preparing a polymerizable composition in the same manner as Example <NUM> except that the blending amounts were modified to <NUM> pbm of HXDI, <NUM> pbm of the polythiol (B-<NUM>-<NUM>) and <NUM> pbm of HDI, and TMTP was not used.

The plastic lens of Comparative Example <NUM> was produced by preparing a polymerizable composition in the same manner as Example <NUM> except that the blending amounts were modified to <NUM> pbm of NBDI and <NUM> pbm of the polythiol (B-<NUM>-<NUM>), and HDI and TMTG were not used.

The plastic lens of Comparative Example <NUM> was produced by preparing a polymerizable composition in the same manner as Example <NUM> except that the blending amounts were modified to <NUM> pbm of NBDI and <NUM> pbm of the polythiol (B-<NUM>-<NUM>), <NUM> pbm of TMDI was used instead of HDI, and TMTG was not used.

The plastic lens of Comparative Example <NUM> was produced by preparing a polymerizable composition in the same manner as Example <NUM> except that <NUM> pbm of xylylene diisocyanate ("XDI") was used instead of IPDI, the blending amount of the polythiol (B-<NUM>-<NUM>) was modified to <NUM> pbm, and HDI and TMTG were not used.

The plastic lens of Comparative Example <NUM> was produced by preparing a polymerizable composition in the same manner as Comparative Example <NUM> except that the blending amounts were modified to <NUM> pbm of XDI and <NUM> pbm of the polythiol (B-<NUM>-<NUM>), and <NUM> pbm of thioglycerin ("TG") was used.

The plastic lens of Comparative Example <NUM> was produced by preparing a polymerizable composition in the same manner as Comparative Example <NUM> except that the blending amounts were modified to <NUM> pbm of XDI and <NUM> pbm of the polythiol (B-<NUM>-<NUM>), and <NUM> pbm of dimercaptomethyldithiane ("DMMD") was used.

The plastic lens of Reference Example <NUM> was produced by preparing a polymerizable composition in the same manner as Example <NUM> except that the blending amounts were modified to <NUM> pbm of IPDI and <NUM> pbm of the polythiol (B-<NUM>-<NUM>), and HDI and TMTG were not used.

The plastic lens of Reference Example <NUM> was produced by preparing a polymerizable composition in the same manner as Example <NUM> except that the blending amounts were modified to <NUM> pbm of IPDI, <NUM> pbm of the polythiol (B-<NUM>-<NUM>) and <NUM> pbm of HDI, and TMTG was not used.

The plastic lens of Reference Example <NUM> was produced by preparing a polymerizable composition in the same manner as Example <NUM> except that the blending amounts were modified to <NUM> pbm of IPDI and <NUM> pbm of the polythiol (B-<NUM>-<NUM>), <NUM> pbm of TMDI was used instead of HDI, and TMTG was not used.

The plastic lens of Reference Example <NUM> was produced by preparing a polymerizable composition in the same manner as Example <NUM> except that the blending amounts were modified to <NUM> pbm of IPDI, <NUM> pbm of the polythiol (B-<NUM>-<NUM>) and <NUM> pbm of TMTG, and HDI was not used.

The plastic lens of Reference Example <NUM> was produced by preparing a polymerizable composition in the same manner as Example <NUM> except that the blending amounts were modified to <NUM> pbm of IPDI and <NUM> pbm of the polythiol (B-<NUM>-<NUM>), <NUM> pbm of TMTP was used instead of TMTG, and HDI was not used.

The plastic lens of Reference Example <NUM> was produced by preparing a polymerizable composition in the same manner as Example <NUM> except that the blending amounts were modified to <NUM> pbm of IPDI and <NUM> pbm of the polythiol (B-<NUM>-<NUM>), <NUM> pbm of BDTG was used instead of TMTG, and HDI was not used.

The plastic lens of Reference Example <NUM> was produced by preparing a polymerizable composition in the same manner as Example <NUM> except that the blending amounts were modified to <NUM> pbm of IPDI and <NUM> pbm of the polythiol (B-<NUM>-<NUM>), <NUM> pbm of BDTP was used instead of TMTG, and HDI was not used.

The plastic lens of Reference Example <NUM> was produced by preparing a polymerizable composition in the same manner as Example <NUM> except that the blending amounts were modified to <NUM> pbm of HMDI and <NUM> pbm of the polythiol (B-<NUM>-<NUM>), <NUM> pbm of hexylisocyanate ("HI") was used instead of HDI, and TMTG was not used.

Compounds and blending amounts of the alicyclic polyisocyanate (A-<NUM>), the non-cyclic aliphatic polyisocyanate (A-<NUM>), the polyisocyanate (A-<NUM>) other than the alicyclic polyisocyanate (A-<NUM>) and the non-cyclic aliphatic polyisocyanate (A-<NUM>), the polythiol (B-<NUM>), the polythiol (B-<NUM>), and the polythiol (B-<NUM>) other than the polythiol (B-<NUM>) and the polythiol (B-<NUM>), which are present in the polymerizable composition used for producing the plastic lenses of Examples, Comparative Examples, and Reference Examples, are shown in the following Table <NUM> and Table <NUM>.

The results of evaluating the plastic lenses of Examples, Comparative Examples, and Reference Examples in terms of Abbe number, heat resistance, striae, transparency, optical distortion, and tensile strength are shown in the following Tables <NUM> and <NUM>.

The plastic lenses of Examples <NUM>-<NUM> were satisfactory in terms of the item for evaluating the striae. They are also satisfactory in terms of the item for evaluating the refractive index, Abbe number, transparency, and optical distortion. On the other hand, the plastic lenses of Comparative Examples <NUM>-<NUM> were not satisfactory in terms of the item for evaluating the striae. Based on this, it was possible to confirm that, by using a polymerizable composition containing an isocyanate component which contains the alicyclic polyisocyanate (A-<NUM>) and the non-cyclic aliphatic polyisocyanate (A-<NUM>) and a polythiol component which contains the polythiol (B-<NUM>) and the polythiol (B-<NUM>), a plastic lens with reduced striae can be obtained.

The plastic lenses of Reference Examples <NUM>-<NUM> were satisfactory in terms of the item for evaluating the striae. However, the evaluation item relating to tensile strength was significantly poorer compared to the plastic lenses of Examples <NUM>-<NUM>. Based on this, it was possible to confirm that, when the alicyclic polyisocyanate (A-<NUM>) and the polythiol (B-<NUM>) are used and also any one of the non-cyclic aliphatic polyisocyanate (A-<NUM>) and the polythiol (B-<NUM>) is used, a plastic lens with reduced striae can be produced but the tensile strength of the lens becomes very low.

Claim 1:
A polymerizable composition comprising an isocyanate component comprising alicyclic polyisocyanate (A-<NUM>)and non-cyclic aliphatic polyisocyanate (A-<NUM>) ; and a polythiol component comprising polythiol (B-<NUM>) and polythiol (B-<NUM>); wherein
- the alicyclic polyisocyanate (A-<NUM>) is at least one of isophorone diisocyanate, methylene biscyclohexyl diisocyanate, bis(isocyanatemethyl)cyclohexane, and bis(isocyanatemethyl)bicyclo[<NUM>.<NUM>]heptane,
- the non-cyclic aliphatic polyisocyanate (A-<NUM>) is at least one of hexamethylene diisocyanate and trimethylhexamethylene diisocyanate,
- the polythiol (B-<NUM>) is at least one of <NUM>,<NUM>-, <NUM>,<NUM>- and <NUM>,<NUM>-bis(mercaptomethyl)-<NUM>,<NUM>,<NUM>-trithiaundecane-<NUM>,<NUM>-dithiol, and,
- the polythiol (B-<NUM>) is at least one of trimethylol propane tris(thioglycolate), trimethylol propane tris(<NUM>-mercaptopropionate), <NUM>,<NUM>-butanediol bis(thioglycolate), and <NUM>,<NUM>-butanediol bis(<NUM>-mercaptopropionate).