JPH08217825A - Optical resin with excellent impact resistance - Google Patents

Abstract

PURPOSE: To obtain an optical resin virtually composed of a specific polymer unit, free from sulfur odor, excellent in impact resistance, useful for e.g. plastic lens of spectacles, without impairing the physical properties inherent therein such as colorless transparency, refractive index, heat resistance, lightweightness, solvent resistance and light resistance. CONSTITUTION: This optical resin is composed of a polymer unit of the formula (R1 and R2 are each H or methyl; X1 and X2 are each O or S; A is a 1-8C alkylene, 6-12C arylene or aralkylene; n is 0-5; when n is 0, at least one of As is S) [e.g. produced from 2,2'-bis(methacryloyloxyethyloxycarbonylthioethyl) sulfide] and, according as needed, another polymer unit derived from a vinyl monomer such as an aromatic vinyl monomer.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical resin having excellent impact resistance, which is preferably used as a plastic lens for spectacles.

[0002]

2. Description of the Related Art In recent years, organic glass has been widely used in place of inorganic glass in the field of spectacle lenses.
The reason why organic glass is used is that it is excellent in lightness, impact resistance, moldability and dyeability. As these organic glasses, cast moldings obtained by polymerizing vinyl monomers such as diethylene glycol bisallyl carbonate and moldings of thermoplastic resins such as polycarbonate have been used.

[0003]

However, the lens obtained from polydiethylene glycol bisallyl carbonate is excellent in heat resistance and impact resistance, but has a problem of low refractive index. On the other hand, polycarbonate
The lens obtained from G.T.E. has excellent refractive index and impact resistance, but there are problems that birefringence occurs due to flow in the molded product and surface hardness decreases.

Therefore, in recent years, various studies have been made on materials for improving the defects of optical resins obtained by cast molding by radical polymerization, or materials aiming at improving the performance of the above resins, and various proposals have been made. There is. For example,
Japanese Patent Publication No. 58-17527, Japanese Patent Publication No. 2-41524
Publication, Japanese Patent Publication No. 58-14449 and Japanese Patent Publication No. 2
JP-A-2883 discloses that bisphenol A, a halide of bisphenol A, or a biphenyl group is introduced into a (meth) acrylic acid ester residue in order to increase the refractive index and heat resistance. There is.

However, although the refractive index and heat resistance are improved in these materials, the impact resistance is lowered because the bulky aromatic group is introduced. Further, when the halogen group is contained, the refractive index can be increased, but the specific gravity becomes large, the lightness originally required for the plastic lens is impaired, and the weather resistance also becomes a problem.

Recently, Japanese Patent Publication No. 3-59061 and Japanese Patent Laid-Open No. 3-109368 propose a (meth) acrylate containing a sulfur atom.
By containing a sulfur atom, it becomes possible to achieve a higher refractive index than ever before. However, the obtained resin is brittle, and it is necessary to increase the content of the copolymerizable monomer in order to obtain satisfactory impact resistance. As a result, there is a problem that the refractive index decreases,
The current situation is that a sufficiently satisfactory resin has not been obtained.

In order to solve this impact resistance problem, Japanese Patent Laid-Open Nos. 2-113027 and 3-2163
No. 8 discloses that a di (meth) acrylate containing sulfur is reacted with a polyfunctional thiol. According to this resin, although the strength is improved, the copolymerizability,
Thermal stability, solvent resistance and light resistance are reduced. Moreover,
The molded product has a problem of sulfur odor due to a decomposition product of residual thiols and thiols and by-products.

The present invention has been made by paying attention to such problems of the prior art. An object of the invention is to provide an optical resin having excellent impact resistance while maintaining physical properties such as colorless transparency, refractive index, heat resistance, light weight, solvent resistance and light resistance.

Another object of the present invention is to provide an optical resin free from sulfur odor generated from unreacted products containing thiol components and by-products.

[0010]

In order to achieve the above object, the invention of an optical resin according to claim 1 comprises a polymer unit represented by the general formula (1).

Further, the invention according to claim 2 comprises a polymer unit represented by the general formula (1) according to claim 1 and a polymer unit formed from a vinyl monomer. .

Furthermore, in the invention described in claim 3, in the invention described in claim 2, the polymer unit formed of a vinyl monomer is a polymer unit formed of a vinyl aromatic monomer. is there.

The present invention will be described in detail below. In the present invention, the polymer unit represented by the general formula (1) which constitutes the optical resin is formed by polymerizing a specific di (meth) acrylate. In this general formula (1), R ₁ and R ₂ are a hydrogen atom or a methyl group, and a methyl group is preferable as R _{1 in} order to enhance the heat resistance of the resin.

A is an alkylene group having a predetermined carbon number,
Of these, an arylene group and an aralkylene group are preferred, and of these, p-phenylene or p-xylylene is preferable from the viewpoint of the refractive index and heat resistance of the molded product. n is an integer of 0 to 5, and an integer of 0 to 2 is preferable. When n exceeds 5, the color tone of the obtained molded product changes, which is not suitable.

Since the polymer unit represented by the general formula (1) has a carbonate group or a thiocarbonate group, the optical resin molded article has high strength such as impact resistance. Can be improved. Moreover, since this polymer unit also has good polymerizability, unreacted substances and by-products are suppressed, and the sulfur odor of the optical resin can be reduced.

As the di (meth) acrylate for forming the polymer unit of the general formula (1), for example, the compounds represented by the following chemical formulas 2 to 27 are used.

[0017]

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[0018]

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[0019]

[Chemical 4]

[0020]

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[0021]

[Chemical 6]

[0022]

[Chemical 7]

[0023]

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[0024]

[Chemical 9]

[0025]

[Chemical 10]

[0026]

[Chemical 11]

[0027]

[Chemical 12]

[0028]

[Chemical 13]

[0029]

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[0030]

[Chemical 15]

[0031]

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[0032]

[Chemical 17]

[0033]

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[0034]

[Chemical 19]

[0035]

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[0036]

[Chemical 21]

[0037]

[Chemical formula 22]

[0038]

[Chemical formula 23]

[0039]

[Chemical formula 24]

[0040]

[Chemical 25]

[0041]

[Chemical formula 26]

[0042]

[Chemical 27]

The amount of this di (meth) acrylate used is
It is preferably in the range of 10 to 95% by weight, more preferably 20 to 80% by weight, based on the whole monomer components. When the amount of di (meth) acrylate used is less than 10% by weight, impact resistance is lowered, and when it exceeds 95% by weight, viscosity is increased and handling becomes difficult, which is not preferable.

Next, in the present invention, the polymer unit represented by the general formula (1) may further contain a polymer unit formed of a vinyl monomer. As the vinyl monomer in this case, a monofunctional or polyfunctional vinyl monomer is used, and it is preferable to use a vinyl aromatic monomer, particularly a styrene-based monomer. When a vinyl aromatic monomer is used, the viscosity of the monomer can be reduced, the specific gravity of the molded product can be reduced to reduce the weight, and the refractive index can be increased. Therefore, these physical properties can be appropriately adjusted by changing the content of the vinyl aromatic monomer.

Examples of the vinyl aromatic monomer include styrene, α-methylstyrene, vinyltoluene, ethylstyrene, p-chlorostyrene, o-chlorostyrene, chloromethylstyrene, p-bromostyrene, o-bromostyrene, Examples thereof include divinylbenzene and divinylbiphenyl. These are used alone or as a mixture.

The amount of these vinyl monomers used is preferably 50% by weight or less based on the total monomers, and is 0-4.
It is more preferable that the amount is 5% by weight or less. If it exceeds 50% by weight, the impact resistance decreases, which is not preferable. In addition,
In this case, the optical resin mainly contains the polymer unit represented by the general formula (1).

Further, vinyl monomers other than vinyl aromatic monomers can be used. By using such a vinyl monomer, physical properties such as heat resistance, refractive index, dyeability and adhesion of the hard coat film can be adjusted.

As the vinyl monomer, specifically,
Vinyl acetate, vinyl propionate, vinyl benzoate, allyl benzoate, (meth) acrylic acid, methyl (meth) acrylate, ethyl (meth) acrylate, isopropyl (meth) acrylate, allyl (meth) acrylate −
Toluene, phenyl (meth) acrylate, benzyl (meth)
Acrylate, p-chlorophenyl (meth) acrylate
, P-chlorobenzyl (meth) acrylate, p-bromophenyl (meth) acrylate, p-bromobenzyl (meth) acrylate, naphthyl (meth) acrylate
G, (meth) acrylamide, N, N-dimethyl (meth)
Acrylamide, (meth) acrylonitrile, 2-hydroxy-3-phenoxypropyl (meth) acryle
Ethylene glycol di (meth) acrylate, diethylene glycol di (meth) acrylate, polyethylene glycol di (meth) acrylate, propylene glycol di (meth) acrylate, dipropylene glycol
Rudy (meth) acrylate, polypropylene glycol di (meth) acrylate, glycerin di (meth) acrylate, 3-acryloyloxyglycerin monomethacrylate, trimethylolpropane tri (meth) acrylate, penta Erythritol tetra (meth) acrylate, 2,2-bis [4- (meth) acryloyloxyphenyl] propane, 2,2-bis [4- (meth) acryloyloxyethoxyphenyl] propane, 2,2- Screw [4-
(Meth) acryloyloxydiethoxyphenyl] propane, 2,2-bis [4- (meth) acryloyloxypropyloxyphenyl] propane, 2,2-bis [4- (meth) acryloyloxydipropyloxyphenyl] propane, 2,2-bis [4- (meth) acryloyloxypolyethoxyphenyl] propane, 2,2-bis [4- (meth) acryloyloxy (2'-hydroxypropyloxy) phenyl] propane, diisopropyl fumarate,
Examples thereof include diisopropyl maleate, dibenzyl fumarate, dibenzyl maleate, dibenzyl mesaconate, maleic anhydride and itaconic anhydride. These are used alone or as a mixture.

Of these, ethylene glycol dimethacrylate and diethylene glycol dimethacrylate
2,2-bis [4-methacryloyloxyphenyl]
Crosslinkable monomers such as propane and 2,2-bis [4-methacryloyloxyethoxyphenyl] propane are preferably used for improving the heat resistance of the optical resin molded product.

The amount of the vinyl monomer used is preferably in the range of 5 to 50% by weight, more preferably 10 to 40% by weight, based on the entire monomer composition. If the amount of the vinyl monomer used is less than 5% by weight, the viscosity of the monomer composition may be high and handling problems may occur. If it exceeds 50% by weight, the impact resistance of the molded product may be increased. Is reduced.

The monomer forming the polymer unit of the general formula (1) can be synthesized, for example, by the following two methods. As a first method, for example, to obtain 2,2′-bis (methacryloyloxyethyloxycarbonylthioethyl) sulfide, 2,2′-bis (mercaptoethyl) sulfide is treated with 2 mol of phosgene, It can be obtained by obtaining 2,2'-bis (chlorocarbonylthioethyl) sulfide and reacting it with 2-hydroxyethyl methacrylate in the presence of an acid binder such as pyridine.

As a second method, 2-chloroethyloxyethyl methacrylate is treated with 1 mol of phosgene to obtain 2-chlorocarbonyloxyethyl methacrylate, and 2,2'-bis ( It can also be obtained by reacting mercaptoethyl) sulfide.

Next, in order to prepare an optical resin molded product having a predetermined shape, for example, a heat curing method and an active energy ray curing method can be mentioned. The heat curing method is a method in which the above-mentioned monomer and a polymerization initiator are mixed to prepare a monomer composition, which is directly charged into a desired mold and heat-cured.

As the polymerization initiator used for heating and curing, an azo polymerization initiator having a 10-hour half-life temperature of 120 ° C. or lower or an organic peroxide can be preferably used. It can be used as a mixture.

Specifically, for example, 2,2-azobis (2,4
-Dimethylvaleronitrile), 2,2-azobisisobutyronitrile, 2,2-azobis (2-methylbutyronitrile), 1,1-azobis (cyclohexane-1-carbonitrile), dimethyl 2,2 ' -Azo-based polymerization initiators such as azobisisobutyrate are preferred.

In addition, benzoyl peroxide, diisopropyl peroxydicarbonate, di-n-propyl peroxydicarbonate, bis (4-t-butylcyclohexyl) peroxydicarbonate, t-butyl peroxide. -Oxyisopropylcarbonate, t-butylperoxybenzoate, 1,1-bis (t-butylperoxy) -3
Organic peroxides such as 3,3,5-trimethylcyclohexane are preferred.

The amount of the polymerization initiator used is preferably 0.05 to 5% by weight, and more preferably 0.1 to 4% by weight, based on the whole monomer composition. At this time, if the amount of the polymerization initiator used is less than 0.05% by weight, the curing will be insufficient and the physical properties of the resulting molded article will deteriorate.
On the other hand, if it exceeds 5% by weight, it becomes difficult to control the curing reaction, and the molded product is liable to be colored, surface cracks and foaming are not preferable.

The curing / molding reaction is preferably carried out by substituting with an inert gas such as nitrogen or helium, carbon dioxide or the like, or in an atmosphere thereof, in order to prevent a decrease in the curing rate due to oxygen and coloring of the molded product.

The curing temperature and the curing time vary depending on the polymerization initiator used, but are 5 to 4 in the range of 20 to 130 ° C.
It is preferably 8 hours. The temperature can be raised appropriately for the purpose of shortening the curing time, completing the curing reaction, and decomposing the unreacted polymerization initiator. Specifically, the temperature is gradually raised from a temperature lower by about 30 ° C. than the 10-hour half-life temperature of the polymerization initiator to be used, and finally the curing is completed at a temperature higher by about 30 ° C. than the 10-hour half-life temperature.

Since the molded product obtained by this heat curing has internal strain, it is desirable to perform annealing treatment. The treatment temperature at that time is preferably 100 to 1
The temperature is 40 ° C, more preferably 110 to 130 ° C, and the treatment time is preferably 30 minutes or more and less than 6 hours, more preferably 1 hour or more and 4 hours or less.

When the monomer composition has a low viscosity or a large curing shrinkage, it is preferable to carry out preliminary polymerization in advance and then charge it in a desired mold to cure it. On the other hand, the active energy ray curing method is a method of charging a monomer and a sensitizer in a mold and irradiating them with an active energy ray such as an ultraviolet ray or an electron beam to cure. Specific examples of the sensitizer used include, for example, benzophenone, 4-phenylbenzophenone, 4-phenoxybenzophenone, 2,2'-diethoxyacetophenone, 2-hydroxy-2-methyl-1.
-Phenylpropan-1-one, benzyl dimethyl ketal, etc. may be mentioned, and they may be used alone or as a mixture.

The amount of the sensitizer used is preferably 0.01 to 1% by weight based on the whole monomer composition,
More preferably, it is 0.02 to 0.5% by weight. On this occasion,
If the amount of the sensitizer used is less than 0.01% by weight, curing will be insufficient and the physical properties of the resulting molded article will deteriorate. On the other hand, 1
When it exceeds the weight%, it becomes difficult to control the curing reaction,
It is not preferable because the molded product is likely to be colored or surface cracked.

By irradiating with this active energy ray, a cured molded article can be easily obtained. The active energy ray preferably has a wavelength in the range of about 200 to 600 nm. Examples of the radiation source include a chemical lamp, a xenon lamp, a low pressure mercury lamp, a high pressure mercury lamp, and a metal halogen lamp.

Since an internal strain exists in the cured molded article by the active energy ray, it is preferably 100 to 140 ° C.,
It is preferable to carry out the annealing treatment at a temperature of 110 to 130 ° C. for 30 minutes or more and less than 6 hours, preferably 1 to 4 hours.

The curing and molding of the monomer mixture is carried out by an inert gas in order to prevent the curing rate from being lowered by oxygen and the coloring of the molding.
For example, it is desirable to replace with nitrogen, helium, carbon dioxide, or the like, or to carry out under that atmosphere.

In the present invention, the heat curing method and the active energy ray curing method can be used together. That is, in the presence of a polymerization initiator and a sensitizer, heating prepolymerization with a polymerization initiator may be performed in advance, and then the mixture may be charged into a desired mold and cured by active energy rays. On the contrary, it is also possible to complete the curing and molding by heat polymerization after preliminarily curing with active energy rays.

Regardless of the heat curing method or the active energy ray curing method, a colorant such as a dye or a pigment, an ultraviolet absorber, an antioxidant, various stabilizers may be added to the monomer composition, if necessary. An antistatic agent, a photochromic compound, a fluorescent brightening agent, an internal mold release agent, a polymerization degree adjusting agent and the like can be added.

As the polymerization degree adjusting agent, carbon tetrachloride, thiol and α-methylstyrene dimer can be used, but it is preferable to use α-methylstyrene dimer from the viewpoint of easy handling and odor. .

The amount thereof used is 0.01 to the monomer composition.
It is preferably 5% by weight, more preferably 1 to 3% by weight. If it is less than 0.01% by weight, the degree of polymerization is not sufficiently adjusted, and if it exceeds 5% by weight, the heat resistance and the weather resistance are significantly lowered due to the decrease in the degree of polymerization, which is not preferable.

A hard coat film can be provided on the surface of the molded article of the present invention to further improve the abrasion resistance of the surface. As a method for applying the hard coat agent, a molded product after completion of curing or a molded product to which a primer liquid is applied,
A method applying a dipping method, a spin coat method, a flow coat method, a spray method or the like is adopted. By providing a primer layer between the surface of the molded product and the hard coat film, the adhesion between the surface of the molded product and the hard coat film can be improved.

In addition, the visible light transmittance can be further enhanced by providing an antireflection coating on the surface of the molded article of the present invention to suppress surface reflection.

[0072]

The present invention will be described in more detail below with reference to examples and comparative examples, but the present invention is not limited to these.

The physical properties of the molded articles prepared according to the examples and comparative examples were measured and evaluated by the methods described below. The results are shown in Tables 1 and 2 below. Refractive index and Abbe number: The refractive index and Abbe number of the molded product were measured using an Abbe refractometer (manufactured by Atago Co., Ltd.).

Impact resistance: Molded product (diameter 8 cm, thickness 1.8 m
A steel ball of 45 g from a height of 127 cm to m) was not broken and was marked as ○, and a cracked one was marked as ×. In addition, 60 g of a steel ball that did not fall when dropped was rated as ◎.

Heat resistance: After the molded product was left in a dryer at 130 ° C. for 2 hours, the molded product was observed visually and deformed by observing the film with a “film orientation viewer” (trade name of Unitikarisa Chilabo). When no change such as cracking, surface deterioration, or coloring was observed at all, it was evaluated as ◯, and when any one was recognized, it was evaluated as x.

Specific gravity: The weight of the molded product by the substitution method in water /
It was determined from the volume of the molded product. Solvent resistance: After leaving the molded product in acetone for 2 hours,
When the molded product did not show any change such as deformation, cracking, or coloring, it was evaluated as ◯, and when it was recognized, as ×.

Optical Distortion: The distortion of the molded product was observed by the above-mentioned "film orientation viewer". The abbreviations for the monomers, azo initiators, and organic peroxides in Table 1 are shown below. Abbreviation of monomer MEEMA represents a compound represented by the following chemical formula 28.

[0078]

[Chemical 28]

MEPMA represents a compound represented by the following chemical formula 29.

[0080]

[Chemical 29]

HSEMA represents a compound represented by the following chemical formula 30.

[0082]

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HSPMA represents a compound represented by the following chemical formula 31.

[0084]

[Chemical 31]

MSEMA represents a compound represented by the following chemical formula 32.

[0086]

Embedded image

MSPMA represents a compound represented by the following chemical formula 33.

[0088]

[Chemical 33]

BTEMA represents a compound represented by the following chemical formula 34.

[0090]

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XTEMA represents a compound represented by Chemical Formula 35 below.

[0092]

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MPSEMA represents a compound represented by the following chemical formula 36.

[0094]

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St: Styrene DVB: Divinylbenzene BAE-2: 2,2-bis (4-methacryloyloxyethoxyphenyl) propane BAH-2: 2,2-bis [4-methacryloyloxy (2 '
-Hydroxypropyloxy) phenyl] propane pCSt: p-chlorostyrene MMA: methyl methacrylate BzMA: benzyl methacrylate EGDM: ethylene glycol dimethacrylate DEGDM: diethylene glycol dimethacrylate TMPTM: trimethylolpropane trimethacrylate To BBAE-2: 2,2-bis (4-methacryloyloxyethoxy-3,5-dibromophenyl) propane BPE-2: 4,4'-bis (methacryloyloxyethoxy) biphenyl XSMA: 4,4-bis (Methacryloylthiomethyl) benzene MPSMA: Bis (4-4'-dimethacryloylthiophenyl) sulfide PETMP: Pentaerythritol tetrakis (3-mercaptopropionate) Abbreviation for polymerization initiator AIBN: 2,2-azobis Isobutyronitrile MAIB: Dimethyl 2,2'-azobisisobutyl - DOO BPO: benzoyl - oxide TBPE: t - Buchirupa --2 - ethylhexanoate Noe -
TBPN: t-Butylpa-oxyneodecanoate (Example 1) 20 g of MEEMA and 0.3 g of TBPE were mixed and placed in a mold (using a silicone gasket) composed of two glass plates. The mixture was heated in a constant temperature bath at 70 ° C. for 12 hours and further at 100 ° C. for 4 hours. After heat curing, the cured molded product was taken out of the mold and annealed at 120 ° C. for 4 hours. (Examples 2 to 11) Curing molding and annealing were performed in the same manner as in Example 1 except that the monomers shown in Table 1 were used, and various physical properties were evaluated. Table 2 shows the results. However,
The polymerization initiator used in molding the monomer composition was 2, 2
-In the case of azobisisobutyronitrile and dimethyl 2,2'-azobisisobutyrate, heat at 65 ° C for 12 hours,
Furthermore, it heated at 100 degreeC for 4 hours.

When benzoylperoxide and t-butylpa-oxy-2-ethylhexanoate were used, heating was carried out at 70 ° C. for 12 hours and then at 100 ° C. for 4 hours. Diisopropyl peroxycarbonate, di-n-
In the case of propylper-oxycarbonate and t-butylper-oxyneodecanoate, heating was carried out at 40 ° C. for 12 hours, and further at 90 ° C. for 4 hours. (Comparative Examples 1 to 10) Molding and annealing were performed in the same manner as in Example 1 except that the monomers shown in Table 1 were used.
Various physical properties were evaluated. The results are shown in Table 2.

[0097]

[Table 1]

[0098]

[Table 2]

From Tables 1 and 2, when the monomer represented by the general formula (1) and the styrene-based monomer are used (Examples 7 to 15), all have excellent impact resistance. Moreover, the refractive index, the Abbe number, and the specific gravity are maintained, and the heat resistance, the solvent resistance, and the surface strain are also well maintained.

When only the monomer represented by the general formula (1) is used (Examples 1 to 3) and the copolymerizability other than the monomer represented by the general formula (1) and the styrene-based monomer. Even when a monomer is used (Examples 4 to 6), impact resistance can be improved while maintaining physical properties such as refractive index and heat resistance. In addition, no sulfur odor was felt in any of Examples 1 to 15. The optical resin of each example also had excellent light resistance.

On the other hand, when a monomer other than the monomer represented by the general formula (1) was used (Comparative Examples 1 to 10), the impact resistance was poor. In addition, when a di- (meth) acrylate containing sulfur and a polyfunctional thiol were reacted (Comparative Example 9,
10) There was a strong sulfur odor due to unreacted substances and by-products.

The technical ideas described in the above embodiments will be described below. (1) The optical resin according to claim 1, which contains the polymer unit represented by the general formula (1) as a main component. According to this structure, the impact resistance can be effectively exhibited while maintaining the physical properties such as the refractive index and heat resistance of the optical resin. (2) The optical resin according to claim ₁ , wherein R _{1 in} the general formula (1) according to claim ₁ is a methyl group. According to this structure, the heat resistance of the optical resin molded product can be improved. (3) The optical resin according to claim 1, wherein X ₁ or X ₂ is a sulfur atom and A is a phenylene group. According to this configuration,
It is possible to improve the refractive index and heat resistance of the optical resin molded product. (4) The optical resin according to claim 3, wherein the polymer unit formed of the vinyl aromatic monomer is a polymer unit formed of a styrene monomer. With this configuration, the specific gravity and the refractive index of the resin molded product can be effectively adjusted. (5) An optical resin molded product obtained by molding the resin according to any one of claims 1 to 3 into a predetermined shape by a heat curing method or an active energy ray curing method. With this configuration,
An optical resin molded article having excellent impact resistance can be obtained while maintaining physical properties such as colorless transparency and refractive index.

[0103]

As described in detail above, according to the invention of the optical resin described in claim 1, the physical properties such as colorless transparency, refractive index, heat resistance, light weight, solvent resistance and light resistance are provided. Impact resistance can be improved while maintaining. Moreover, it is possible to eliminate the sulfur odor generated from unreacted substances and by-products that contain the thiol component.

According to the second aspect of the present invention, the viscosity of the monomer composition can be further adjusted, and the physical properties of the optical resin such as specific gravity, refractive index, heat resistance and dyeability can be easily adjusted. It can be adjusted.

According to the third aspect of the present invention, it is possible to effectively reduce the viscosity of the monomer composition, reduce the weight of the optical resin molding, and improve the refractive index.

Claims (3)

[Claims] 1. An optical resin comprising a polymer unit represented by the following general formula (1). Embedded image In the formula, R ₁ and R ₂ are hydrogen atoms or methyl groups, n is an integer of 0 or more and 5 or less, X ₁ and X ₂ are oxygen atoms or sulfur atoms,
A represents a group selected from an alkylene group having 1 to 8 carbon atoms, an arylene group having 6 to 12 carbon atoms, and an aralkylene group, and n
= In the case expression 0 -X ₁ AX ₂ - in at least one sulfur atom. 2. An optical resin comprising a polymer unit represented by the general formula (1) according to claim 1 and a polymer unit formed of a vinyl monomer. 3. The optical resin according to claim 2, wherein the polymer unit formed of a vinyl monomer is a polymer unit formed of a vinyl aromatic monomer.