JPH0431361B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a plastic lens for spectacles,
In particular, it provides excellent physical properties required for plastic lenses for eyeglasses, such as transparency, surface precision, surface hardness, heat resistance, impact resistance, chemical resistance, processability, etc., and also provides a manufacturing method with less optical distortion. It is. As a conventional plastic lens material for eyeglasses,
Diethylene glycol bisallyl carbonate resin (hereinafter abbreviated as CR-39 resin) is commonly used, and the demand for it as an alternative to glass lenses is increasing year by year. The reason for this is that plastic lenses have advantages for users such as being lighter than glass lenses, having high impact resistance, being safe, and being fashionable as they can be dyed in various colors. The refractive index of the lens is N _D = 1.50, which is lower than the refractive index of ordinary glass, N _D = 1.523, so the edge thickness of the lens increases when the strength of a negative lens increases, and the center thickness of the lens increases when the strength of a positive lens increases. It is not aesthetically pleasing. Furthermore, plastic lenses with a relatively high refractive index, such as polycarbonate and polystyrene, are unsuitable for producing a wide variety of products such as eyeglass lenses. Furthermore, these lenses have poor surface hardness, heat resistance, impact resistance, chemical resistance, etc., and their use is limited to only a few areas. A method of copolymerizing styrene and methyl methacrylate or acrylonitrile to improve surface hardness and weather resistance to some extent is already known, but heat resistance, chemical resistance, etc. are hardly improved, and the refractive index is lower than that of the second component. decreases as the copolymerization ratio increases. Also polyvinylnaphthalene, polyvinylcarbazole,
Although a high refractive index can be obtained with polynaphthyl methacrylate and the like, it cannot be used as a plastic lens for eyeglasses because it is significantly colored and has extremely poor impact resistance and weather resistance. As a result of intensive research to overcome the above-mentioned defects as a plastic lens for eyeglasses, the present inventors have found that at least one type of plastic lens selected from Group A below
Obtained by radical polymerizing a liquid mixture consisting of a monomer, at least one second monomer selected from Group B, and a dimer of α-methylstyrene in the presence of a radical polymerization initiator. The present invention was achieved by discovering that a plastic lens for spectacles made of a copolymer has good physical properties and little optical distortion. Group A general formula (In the formula, a and b represent integers from 0 to 4, and R ₁ and
_R2 represents H or _CH3 , _R3 is -O-, -S-,
−CO−, −SO ₂ −, −CH ₂ −, −CH=CH−,

[Representing formula]), Group B general formula (In the formula, _R1 represents H or _CH3 , X represents H or a halogen other than fluorine, a represents an integer of 0 to 5, and b represents an integer of 0 to 5). When radically polymerizing a liquid mixture consisting of at least one first monomer selected from Group A and at least one second monomer selected from Group B, polymerization of those monomers. The reaction rate is fast, and the difference in polymerization reaction rate between the monomers to be combined tends to be large. Therefore, in order to obtain lenses by cast polymerization, the amount of radical polymerization initiator added must be small, and the initial stage of polymerization must be It is necessary to cure it for a relatively long time by keeping the temperature low. Tokukai Akira
In 57-2312, α-methylstyrene is added as a third monomer when copolymerizing dimethacrylate or diacrylate having an aromatic group with a radically polymerizable second monomer having an aromatic group. It is said that by copolymerizing the resin, the polymerization rate is reduced, and the surface hardness of the resin obtained by cast polymerization is good, with almost no surface irregularities caused by shrinkage. However, when copolymerizing dimethacrylate or diacrylate having an aromatic group with a radically polymerizable second monomer having an aromatic group, if α-methylstyrene is added as a third monomer amount and the copolymerization is carried out, The steric hindrance of the methyl group at the α-position of α-methylstyrene slows down the copolymerization rate, which may lead to improvements in moldability and surface precision depending on the monomer used, but in the case of α-methylstyrene, this It has a strong effect as a chain transfer agent or polymerization degree regulator, and is a radical-polymerizable secondary compound having aromatic groups such as dimethacrylate or diacrylate.
When copolymerizing monomers, adding α-methylstyrene as a third monomer may suppress the degree of polymerization to an unnecessarily low level. Shrinkage is not sufficient and tends to shrink and harden in a single hour at the final stage of the copolymerization reaction. Therefore, the resulting resin is brittle, and various physical properties important for a plastic eyeglass lens, such as surface hardness, heat resistance, impact resistance, chemical resistance, and processability, are deteriorated. Furthermore, the rapid shrinkage behavior results in an unnecessarily increased optical strain. As described above, although moldability and surface precision are improved by the addition of α-methylstyrene, in many cases important physical properties for plastic lenses for eyeglasses are deteriorated and optical distortion is increased. When copolymerizing dimethacrylate or diacrylate having an aromatic group with a radically polymerizable second monomer having an aromatic group, α is used as a third monomer.
-As a result of copolymerization with the addition of methylstyrene,
This leads to improved moldability and surface precision, and can only be obtained as a plastic lens for eyeglasses in very limited cases. As a result of repeated studies on various chain transfer agents or polymerization degree regulators, the present inventors have found that at least one first monomer selected from Group A described below and at least one selected from Group B When radically polymerizing a liquid mixture with one or more second monomers in the presence of a radical polymerization initiator, Group A General formula (In the formula, a and b represent integers from 0 to 4, and R ₁ and
_R2 represents H or _CH3 , _R3 is -O-, -S-,
−CO−, −SO ₂ −, −CH ₂ −, −CH=CH−,

[Formula]), Group B general formula (In the formula, a represents an integer from 0 to 5, and b represents an integer from 0 to 5.
). By adding α-methylstyrene dimer, it has good physical properties such as surface hardness, heat resistance, impact resistance, chemical resistance, processability, etc., which are important for plastic lenses for eyeglasses, and surface accuracy, and has low optical distortion. It has been found that a resin can be obtained. More specifically, a mixed solution of at least one or more first monomers selected from Group A and at least one or more second monomers selected from Group B,
When performing radical polymerization in the presence of a radical polymerization initiator, by adding 0.03 to 3.0 parts by weight of α-methylstyrene dimer to the total monomers,
α-Methylstyrene dimer acts as a chain transfer agent or polymerization degree regulator in copolymerization reactions, and its action is milder than other chain transfer agents or polymerization degree regulators, so rapid radicals due to polymerization heat generation Progress of polymerization (auto-promotion effect or gel effect)
is suppressed to an appropriate level, it is possible to obtain a relatively mild radical polymerization reaction from the initial stage to the latter half of the radical polymerization. Therefore, the shrinkage behavior progresses relatively slowly from the start of radical polymerization to gelation to curing, and optical distortion due to polymerization shrinkage can be reduced. Furthermore, since radical polymerization does not proceed runaway, various physical properties of the resulting resin, such as surface hardness,
It has good heat resistance, impact resistance, chemical resistance, workability, etc., and improves moldability and surface precision at the same time. Other chain transfer agents or polymerization degree regulators, such as various mercaptans, dialkyl disulfides, tetrathiuram disulfides, thiuram disulfides, chloroform, carbon tetrachloride,
When carbon tetrabromide is used, its effect as a chain transfer agent or polymerization degree regulator is too strong, so the degree of polymerization of the resulting resin is kept lower than necessary, resulting in poor surface hardness and heat resistance. Physical properties such as hardness, impact resistance, chemical resistance, and processability may deteriorate,
It cannot be obtained as a plastic lens for eyeglasses because it causes an increase in optical distortion and coloration due to the chain transfer agent or the adjustment of the degree of polymerization. In order to obtain the plastic lens for spectacles according to the present invention, at least one first monomer selected from Group A and at least one second monomer selected from Group B are combined with α- A predetermined amount of a radical polymerization initiator is added to a mixed solution of 0.03 to 3.0 parts by weight of methylstyrene dimer based on the total monomers, and if necessary, an ultraviolet absorber, a heat stabilizer, and a color inhibitor are added. It is obtained by adding various stabilizers such as antioxidants, pouring into a mold consisting of a mold and a gasket, and curing with heat or ultraviolet rays. The radical polymerization initiator used here is not particularly limited and any known one can be used. Typical examples are methyl ethyl ketone peroxide, cyclohexanone peroxide,
Ketone peroxides such as 3,3,5-trimethylcyclohexanone peroxide, methylhexanone peroxide, acetylacetone peroxide, 1,1-bis(t-butylperoxy)3,3,5-trimethylcyclohexanone, 1,1 -bis(t-butylperoxy)cyclohexanone, 2,2-bis(t-butylperoxy)octane, n-butyl 4,4-bis(t-
butylperoxy)valerate, peroxyketals such as 2,2-bis(t-butylperoxy)butane, t-butyl hydroperoxide, cumene hydroperoxide, diisopropylbenzene hydroperoxide, p-menthane hydroperoxide , 2,5-dimethylhexane 2,5-dihydroperoxide,
Hydroperoxides such as 1,1,3,3-tetramethylbutyl hydroperoxide, di-t-butyl peroxide, t-butylcumyl peroxide, dicumyl peroxide, α-
Bis(t-butylperoxy)benzene, 2,5
-Dialkyl peroxides such as dimethyl-2,5-di(t-butylperoxy)hexane, 2,5-dimethyl-2,5-di(t-butylperoxy)hexyne-3, acetyl peroxide, isobutyl liperoxide, octanoyl peroxide, decanoyl peroxide, lauroyl peroxide, 3,3,5-trimethylhexanoyl peroxide, scnic acid peroxide, benzoyl peroxide,
2,4-dichlorobenzoyl peroxide, m
- Diacyl peroxides such as toroxyperoxide, diisopropyl peroxydicarbonate, di-2-ethylhexyl peroxydicarbonate, di-n-propyl peroxydicarbonate, dimyristyl peroxydicarbonate, di-2-ethoxy Peroxycarbonates such as ethyl peroxydicarbonate, di-methoxyisopropyl peroxydicarbonate, di(3-methyl-3-methoxybutyl)peroxydicarbonate, t-butylperoxyacetate, t-butylperoxyiso butyrate, t-
Butyl peroxy pivalate, t-butyl peroxy neodecanate, cumyl peroxy neodecanate, t-butyl peroxy-2-ethylhexanoate, t-butyl peroxy 3,5,5-
Trimethylhexanoate, t-butylperoxylaurate, t-butylperoxybenzoate, di-t-butyldiperoxyisophthalate, 2,5-dimethyl-2,5-di(benzoylperoxy)hexane, t -Organic peroxides represented by peroxy esters such as butyl peroxymaleic acid and t-butylperoxyisopropyl carbonate, azobis systems such as 2,2'-azobisisobutyronitrile, benzoin alkyl ethers, etc. can be used. Furthermore, various stabilizers such as ultraviolet absorbers, heat stabilizers, coloring inhibitors, and antioxidants are not particularly limited. The amount of the α-methylstyrene dimer used in the present invention is preferably in the range of 0.03 to 3.0 parts by weight, particularly preferably 0.05 to 2.0 parts by weight, based on the total monomers. If the amount of α-methylstyrene dimer added is less than 0.03 parts by weight, the α-methylstyrene dimer will not function as a chain transfer agent or polymerization degree regulator, making it difficult to control the polymerization reaction. Yes, the amount of α-methylstyrene dimer added is 3.0
If the amount is more than 1 part by weight, the degree of polymerization of the obtained resin will be too low, and in either case, the obtained resin will have various physical properties important as a plastic lens for eyeglasses, such as:
Surface hardness, heat resistance, impact resistance, chemical resistance, processability, etc. may decrease, optical distortion may increase, the mold may come off during curing, or cracks may occur, making it impossible to obtain a lens. The examples described below serve to better explain the invention and are not intended to limit the scope of the invention. Incidentally, the percentages and parts in the examples are based on weight unless otherwise specified. Example 1 0.2 parts of lauroyl peroxide as a radical polymerization initiator was added to a mixed solution consisting of 20 parts of bisphenol A dimethacrylate, 80 parts of phenyl methacrylate, and 2.0 parts of α-methylstyrene dimer.
2-(2-hydroxy-5-
t-octylphenyl)benzotriazole 0.1
After stirring thoroughly, the mixture was poured into a mold consisting of a glass mold with a diameter of 70 mm and an elastomer spacer, and heated from 60°C to 90°C over 22 hours. The refractive index, surface hardness, heat resistance, impact resistance, chemical resistance, processability, etc. of the copolymer taken out from the mold were measured. The resulting copolymer was colorless and transparent, had a refractive index of 1.57, and a pencil hardness of 4H. Furthermore, the surface hardness, heat resistance, impact resistance, chemical resistance, processability, etc. were better than when α-methylstyrene was used, and the optical distortion was lower than when α-methylstyrene was used. Example 2 The same procedure as in Example 1 was carried out except that benzyl methacrylate was used instead of phenyl methacrylate. The resulting copolymer was colorless and transparent, had a refractive index of 1.57, and a pencil hardness of 3H. Furthermore, the surface hardness, heat resistance, impact resistance, chemical resistance, processability, etc. were better than when α-methylstyrene was used, and the optical distortion was lower than when α-methylstyrene was used. Example 3 The same procedure as Example 1 was carried out except that styrene was used instead of phenyl methacrylate. The resulting copolymer was colorless and transparent, had a refractive index of 1.59, and a pencil hardness of 4H. Furthermore, the surface hardness, heat resistance, impact resistance, chemical resistance, processability, etc. were better than when α-methylstyrene was used, and the optical distortion was lower than when α-methylstyrene was used. Comparative Example 1 The same procedure as in Example 1 was carried out except that α-methylstyrene was used instead of the α-methylstyrene dimer. The resulting copolymer was colorless and transparent and had a refractive index of 1.57, but the surface hardness, heat resistance, impact resistance, chemical resistance, processability, etc. It was inferior to using the body. Furthermore, the optical strain was greater than when using a dimer of α-methylstyrene. The refractive index was measured using an Atsube refractometer, and the pencil hardness (surface hardness) was measured according to JIS (K-4000). Other physical properties were measured by the methods described below. Heat resistance: After leaving the lens in a hot air dryer at 120° C. for 3 hours, the lens was taken out and passed if no coloration or surface distortion was observed with the naked eye. Impact resistance: Lenses with a center wall thickness of 2 mm were tested in accordance with FDA standards. Chemical resistance: Lenses were immersed in methanol, acetone, benzene, toluene, 10% hydrochloric acid aqueous solution, and 10% sodium hydroxide aqueous solution for 200 hours, and the lens passed if the surface did not cloud or swell in any solvent or aqueous solution. . Optical strain: The difference in optical strain was compared for the resins obtained in Examples and Comparative Examples using a strain meter consisting of two polarizing plates. Examples 4 to 10 Lenses of various compositions were created by the same method as in Example 1, and the results are listed in Table 1 as Examples and Comparative Examples. However, the polymerization conditions such as the radical polymerization initiator, the amount added, and the polymerization temperature and time may be different from those in Example 1. As is clear from Table 1, the lenses obtained by the present invention have superior physical properties such as surface hardness, heat resistance, impact resistance, chemical resistance, and processability, and have less optical distortion than the lenses shown in the comparative examples. .

[Table] The abbreviations used in Table 1 are listed below. BPDMA Bisphenol A dimethacrylate Br ₄ BPDMA Tetrabromo bisphenol A dimethacrylate PhMA Phenyl methacrylate BzMA Benzyl methacrylate St Styrene BrSt Bromstyrene Br ₃ PhMA Tribromo phenyl methacrylate Br ₃ BzMA Tribromo benzyl methacrylate α-MSD α-Methyl styrene Dimeric α-MStα-methylstyrene

Claims (1)

[Claims] 1 At least one or more first monomers selected from the following group A and at least one or more second monomers selected from group B, and the amount added is based on the total monomers. for
A plastic lens for eyeglasses made of a copolymer obtained by radical polymerizing a mixture of 0.03 to 3.0 parts by weight of a dimer of α-methylstyrene in the presence of a radical polymerization initiator: Group A general formula (In the formula, a and b represent integers from 0 to 4, and R ₁ and
_R2 represents H or _CH3 , _R3 is -O-, -S-,
−CO−, −SO ₂ −, −CH ₂ −, −CH=−CH−,
[Representing formula]), Group B general formula (In the formula, _R1 represents H or _CH3 , X represents H or a halogen other than fluorine, a represents an integer of 0 to 5, and b represents an integer of 0 to 5).