JPH0248083B2 - GOSEIJUSHIRENZU - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a synthetic resin lens with high dimensional stability.

[Prior art]

Methacrylic resin, whose main component is methyl methacrylate, not only has excellent transparency and weather resistance, but also has excellent mechanical properties and
It has well-balanced thermal properties, moldability, etc., and is used for various optical applications.

In particular, when used as optical lenses, it is expected that the demand for it will further increase in the future due to its advantages such as lighter weight and mass production compared to conventional inorganic glasses.

However, on the other hand, methacrylic resin has higher hygroscopicity than other transparent materials such as polystyrene and polycarbonate, and has disadvantages such as deformation and warping of products when left in humid environments for long periods of time. I have both. For this reason, there are some fields in the field of precision optics where the use of methacrylic resin lenses is restricted.

[Problems to be Solved by the Invention] An object of the present invention is to develop a synthetic resin lens with high dimensional stability in view of the prior art as described above.

[Means for solving the problems] The synthetic resin lens of the present invention contains 10 to 90% by weight of methyl methacrylate and phenyl methacrylate.
Consisting of 10-90% by weight copolymer.

The resin used in the lens of the present invention needs to contain 10 to 90% by weight of methyl methacrylate as a constituent component. If it is less than 10% by weight, the inherent properties of the methacrylic resin will be impaired, and if it exceeds 90% by weight, the effect of reducing hygroscopicity will be small. Also, the second
It is important that the component phenyl methacrylate is contained in the copolymer in an amount of 10 to 90% by weight. Ten
If it is less than 90% by weight, there is no effect of reducing hygroscopicity.
If it exceeds % by weight, the mechanical properties will deteriorate. Furthermore, other copolymerizable monomers such as methyl acrylate, ethyl (meth)
Acrylate, butyl (meth)acrylate, 2
- Alkyl (meth)acrylate having a straight chain or branched alkyl group having 1 to 8 carbon atoms such as ethylhexyl (meth)acrylate, cyclohexyl (meth)acrylate, styrene, acrylonitrile, etc. up to 20% by weight, preferably 1 to 8% by weight; 15% by weight can be introduced.

The resin composed of the above components used in the lens of the present invention can be easily obtained by copolymerizing the monomer component compositions thereof. For the polymerization, any conventionally known method such as suspension polymerization, emulsion polymerization, bulk polymerization, solution polymerization, etc. can be employed.

In the suspension polymerization method, for example, a monomer mixture containing a radical polymerization initiator and a chain transfer agent for controlling molecular weight is dispersed in water in which a suspension dispersant is dissolved, and then the monomer mixture is dispersed at a temperature range of 50 to 130°C. It is sufficient to polymerize for several hours.

In addition, in the bulk polymerization method by casting, a radical polymerization initiator is added to a monomer mixture blended in a predetermined ratio, and then poured into a reinforced glass or stainless steel cell fitted with a vinyl chloride frame. 0.3-15 hours at 45-90℃, then 10 hours at 80-150℃
It takes between minutes and 5 hours.

Examples of the polymerization initiator used in each of the above polymerization methods include free radical initiators such as diacyl peroxide, peroxy ester, dialkyl peroxide, ketone peroxide, and azobis-based compounds. It is also possible to use a redox polymerization initiator, such as a combination of peroxides and amines.
These polymerization initiators can be used not only alone but also in combination of two or more types, and the amount used is 0.001 to 1 part by weight per 100 parts by weight of the monomer mixture.

In addition, in each of the above-mentioned polymerization methods, as a chain transfer agent for controlling the degree of polymerization, for example, alkyl mercaptan, thioglycolic acid and its ester, β-
Aromatic mercaptans such as mercaptopropionic acid and its esters, thiophenol, and thiocresol are used.

Furthermore, antioxidants,
Antistatic agents, ultraviolet absorbers, mold release agents, and other additives may be added.

The synthetic resin lens according to the present invention can be produced by a method of injecting the monomer mixture or a partial polymer thereof into a lens mold and polymerizing it by casting, or by injection molding or molding a copolymer produced by the polymerization method described above. It can be easily obtained by compression molding or by cutting and polishing a copolymer block.

〔Example〕

Hereinafter, the present invention will be explained in more detail based on Examples and Comparative Examples.

Example 1 To a mixture of 100 g of methyl methacrylate and 100 g of phenyl methacrylate, 0.1 g of 2,2'-azobis(2,4-dimethyl)valeronitrile was added and uniformly dissolved. This mixture was injected into a lens mold through a gasket and heated at 65°C for 6 hours and then at 120°C for 3 hours to cure. After cooling, the center part was removed from the mold with a thickness of 3 mm and a diameter of 20 mm.
The lens has extremely good transparency and a surface accuracy of 50
℃, and after being left in water for 12 hours, no change was observed in the number of changes in Newton's ring by optical measurement. Also, the heat distortion temperature of this lens is ASTM
−D648 method showed 105℃.

On the other hand, when 100% methyl methacrylate was polymerized in the same manner, the number of Newton rings changed was five.

Example 2 Except that the monomer composition was changed to 60 g of methyl methacrylate and 140 g of phenyl methacrylate,
A lens was produced by repeating the same method as in Example 1. No change in Newton's ring was observed in this lens, and the thermal deformation temperature was as high as 107°C.

Example 3 9000 g of ion-exchanged water was placed in a 20 glass flask equipped with a stirrer and a reflux condenser, and then a copolymer of methyl methacrylate and sodium salt of 2-sulfoethyl methacrylate was added as a dispersant.
1.2 g and 30 g of sodium sulfate were added and dissolved. After that, 3900g of methyl methacrylate, 1800g of phenyl methacrylate, methyl acrylate
300 g of monomer mixture, 60 g of azobisisobutyronitrile as a polymerization initiator, 12 g of n-octyl mercaptan as a chain transfer agent, and 6.0 g of stearic acid monoglyceride as a mold release agent.
The polymerization raw material which had been added and dissolved was put into the flask. After purging with nitrogen, polymerization was carried out at 80°C for 2 hours and then at 98°C for 2 hours while stirring at 350 rpm. After washing the obtained beaded polymer with water,
The mixture was separated and dried at 75°C for 24 hours, and then extruded into pellets using a 30 mm extruder with a vent. The obtained pellets were injection molded at a cylinder temperature of 240°C and a mold temperature of 60°C to obtain a lens with a center thickness of 2.5 mm and a diameter of 20 mm. After this lens was left in water at 50° C. for 12 hours, the number of Newton rings changed was as small as 0 to 1.

On the other hand, ordinary methacrylic resin
In the injection molded product manufactured by VH (registered trademark, manufactured by Mitsubishi Rayon Co., Ltd.), the number of Newton rings changed was five.

〔Effect of the invention〕

As mentioned above, the synthetic resin lens of the present invention has lower hygroscopicity and excellent dimensional stability than conventional methacrylic resin lenses, so it can be used for eyeglass lenses, sunglass lenses, camera lenses, and automobile lamp lenses. In addition, it is useful as optical lenses such as Fresnel lenses, lenticular lenses, and microprism matte lenses that have special shapes that are difficult to process using inorganic materials.

Claims (1)

[Claims] 1. A synthetic resin lens made of a copolymer of 10 to 90% by weight of methyl methacrylate and 10 to 90% by weight of phenyl methacrylate.