JPH0848725A - High-refractive index resin for optical material excellent in heat resistance - Google Patents

Abstract

PURPOSE:To obtain a resin for optical material high in glass transition temp. and refractive index by using a copolymer obtd. by copolymerizing a specific compd. with a radical-polymerizable monomer. CONSTITUTION:4-Vinylbiphenyl is copolymerized with at least one of radical- polymerizable monomers such as arom. vinyl monomers, vinyl cyanide monomers, and (meth)acrylic esters (e.g. styrene and methyl methacrylate) to obtain a copolymer, which is used in the objective resin, wherein the 4- vinylbiphenyl copolymer is incorporated pref. in an amt. of 10 to 90wt.% based on the whole resin.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vinyl-based resin for optical materials. More specifically, by incorporating 4-vinylbiphenyl into a vinyl-based polymer main chain, it is possible to improve the refractive index and heat resistance in terms of product quality. An object is to provide an excellent resin for optical materials.

[0002]

2. Description of the Related Art Vinyl resins are widely used in home appliances, sundries, automobiles, etc., and are one of the essential materials in our daily lives. Vinyl resins are also widely used in the field of optical materials, and are used for plastic lenses, prisms and the like. Among them, especially polymethylmethacrylate resin
Due to its transparency, surface hardness, heat resistance, and refractive index, (PMMA resin) is used for optical applications and as a transparent molding material.
It is desired to further improve the heat resistance and the refractive index according to the demands of the fields of application of these vinyl resins. Therefore, a methyl methacrylate-styrene resin (MS resin) obtained by copolymerizing styrene with methyl methacrylate is used.

[0003]

[Problems to be Solved by the Invention] Although MS resin is cheaper than PMMA resin and has a high refractive index and excellent moldability,
Due to its poor heat resistance and surface hardness, there is no end to the demand for improvements in the field of large-sized optical molding materials such as the full-nel lens of large-screen projection TVs. The biggest points in lens design are the reduction in the size and weight of molding materials, and the suppression and elimination of aberrations. To this end, materials with a high refractive index are required.
Further, temperature stability of the refractive index is also required, and a material having a high glass transition temperature (heat resistance) and a small linear expansion coefficient is desired.

[0004]

SUMMARY OF THE INVENTION In view of the above circumstances, the present inventors have conducted research and as a result have made the present invention which provides heat resistance and a high refractive index. That is, the present invention is for an optical material having excellent heat resistance, which is characterized by comprising a copolymer obtained by copolymerizing 4-vinylbiphenyl and a radical-polymerizable monomer, alone or in combination. The present invention relates to a high refractive index resin. Further, it is a high-refractive-index resin for optical materials having excellent heat resistance, which contains a 4-vinylbiphenyl polymer within a range of 10% by weight or more and 90% by weight or less of the total amount of the resin.

The 4-vinylbiphenyl used in the present invention is a powder crystal having a melting point of 121 ° C. and contains some alkylbiphenyl impurities such as 4-ethylbiphenyl and 4-methylbiphenyl during the production. These are preferably 10% by weight or less, and particularly preferably 5% by weight or less based on the whole. These impurities elute over time after forming a molded article such as a lens, and become a factor that obstructs the lens surface such as clouding, dirt, and weather resistance. In addition, the uniformity of hard coating or multi-coating is lacked in the surface treatment of the lens, which may cause the phenomenon of peeling of the treatment layer, so it is preferable that the amount is as small as possible. The compounding amount of 4-vinylbiphenyl with respect to the total amount of the raw material monomers is not particularly limited, and usually 0.05% by weight or more of the total amount of the raw material monomers is sufficient, but especially methyl methacrylate resin is used as a heat-resistant grade for industrial optical lenses. Based on the glass transition temperature (Tg) of (PMMA) or higher, in order to obtain Tg ≧ 107 ° C., 4-vinylbiphenyl is used as a starting material when styrene with a low Tg is used as a copolymerization monomer. It is preferably 10% by weight or more and 90% by weight or less of the total amount of the body, and more preferably 15% by weight or more and 80% by weight or less of the total amount of the raw material monomers in consideration of imparting high refractive index.

Here, 4-vinylbiphenyl and a radical-polymerizable monomer are aromatic vinyl monomers such as styrene, vinyl cyanide monomers such as acrylonitrile, and (meth) acryl such as methyl methacrylate. Acid Ester,
Other monomers. These monomers may be copolymerized alone or in any combination of plural kinds with 4-vinylbiphenyl.

Specifically, as aromatic vinyl monomers, side chain alkyl-substituted styrenes such as styrene and α-methylstyrene, nuclear alkyl-substituted styrenes such as vinyltoluene, halogenated styrenes such as bromostyrene and chlorostyrene,
Examples include divinylbenzene and vinylnaphthalene. Examples of vinyl cyanide-based monomers include acrylonitrile, methacrylonitrile, fumaronitrile, maleonitrile, α-chloroacrylonitrile and the like. (Meth) acrylic acid esters include methyl methacrylate, ethyl methacrylate, propylene methacrylate, butyl methacrylate, amyl methacrylate, hexyl methacrylate, phenyl methacrylate, methyl acrylate, ethyl acrylate, amyl acrylate, hexyl acrylate, octyl acrylate, 2-ethylhexyl acrylate. , Cyclohexyl acrylate, dodecyl acrylate, phenyl acrylate, benzyl acrylate, etc.

Other monomers include maleic acid, maleic acid esters, itaconic acid and itaconic acid esters, N-alkylmaleimides, N-phenylmaleimide.
Various polymerizable monomers such as (PMI) s can be used. Derivatives obtained by introducing a halogen group such as chlorine, bromine or iodine, or sulfur into the above-mentioned monomers can also be effectively used as a means for improving the refractive index.

In the production of the copolymer of the present invention, at the time of polymerization, a radically polymerizable monomer is preliminarily added, if necessary, together with a polymerization initiator, a molecular weight modifier, a solvent and other polymerization auxiliary agents. 4-vinyl biphenyl is added and blended in a predetermined amount. The polymerization method itself is suitable for batch polymerization such as suspension, emulsification, solution, and bulk, or continuous polymerization, but at a temperature above the melting point.
-Melt-feed vinyl biphenyl to the polymerization system,
It may be dissolved in a polymerized monomer or the like and fed to the polymerization system,
It has wide application to the process.

The polymerization initiation method for 4-vinylbiphenyl and one or more of the above radical-polymerizable monomers may be either thermal initiation or initiator initiation. When the initiator is initiated, the polymerization initiator may be either an organic peroxide or an azo compound. Here, as the organic peroxide, for example, t-
Hexyl peroxyisopropyl monocarbonate, t-
Hexyl peroxy-2-ethylhexanoate, t-butylperoxy-3.5.5-trimethylhexanoate, peroxyesters such as t-butylperoxyisopropyl carbonate, 1,1-bis (t-hexyl) Peroxy) 3,3,5-
Peroxyketals such as trimethylcyclohexane,
Examples thereof include diacyl peroxides such as lauroyl peroxide. The initiator of the azo compound, for example, 2,2'-azobisisobutyronitrile,
Examples thereof include azonitriles such as 2,2'-azobis (2-methylbutyronitrile) and 1,1'-azobis (cyclohexane-1-carbonitrile). The half-life temperature of the initiator is T ₁ (1
The time half-life temperature) is preferably about 80 ° C to 120 ° C, and the polymerization temperature is preferably T ₁ + 5 ° C to about 20 ° C. The crosslinking efficiency of the initiator needs to be selected in consideration of the specificity of the process and the case of using it in combination with other crosslinking agents and additives. In any case, there is no particular limitation.

Further, molecular weight regulators to be appropriately blended when obtaining these resins are mercaptans such as t-dodecyl mercaptan, n-dodecyl mercaptan and n-octyl mercaptan,
Mention may be made of monoterpenoids such as 1-methyl-4-isopropylidenecyclohexene and styrene dimers such as 2,4-diphenyl-4-methyl-1-pentene. However, mercaptans have a drawback of odor, and monoterpenoids are natural products and may contain a large amount of impurities, which may cause deterioration of hue. 2,4-diphenyl-4-methyl-1-pentene and the like undergo degenerative chain transfer depending on the polymerization temperature, and thus the conversion rate does not increase and may cause deterioration of productivity. It is necessary to select any molecular weight regulator after grasping these characteristics. In either case, there is no particular limitation.

In the polymerization, n-octadecyl-3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate and 2,6-di-, depending on the use expected for optical materials.
hindered phenols such as t-butyl-4-methylphenol, trisnonylphenyl phosphite, tris (2,
4-di-t-butylphenyl) phosphorus such as phosphite, sulfur such as pentaerythrityl tetrakis (3-laurylthiopropionate), 2- [1- (2-hydroxy-3,5-di- A phenol acrylate-based antioxidant such as t-pentylphenyl) ethyl] -4,6-di-t-pentylphenyl acrylate may be added. Also, a solvent such as methyl ethyl ketone or ethyl benzene, an ultraviolet absorber, an anti-coloring agent, an antistatic agent, a fluorescent paint, a release agent, and other stabilizers may be added and used. The resin thus obtained can be used to manufacture a molded body for any optical material by using an injection molding method, an extrusion molding method, or the like. In order to more specifically describe the present invention, examples and comparative examples are shown below.

[0013]

Embodiments of the present invention will be described. Polymerized Monomer,
A raw material charge liquid consisting of solvent, molecular weight modifier, initiator and other additives is equipped with heat exchanger, stirring blade and temperature control function 1.
Place in a 000 cc separable flask and polymerize for a predetermined time. The obtained polymer solution was placed in a vacuum dryer and treated at 200 ° C. for 2 hours under full vacuum to obtain a resin. The obtained resin was molded by Toshiba Machine J-15 injection molding machine at molding temperature of 200 ℃
A color plate with a length of 4.0 mm, a length of 76.2 mm and a width of 50.8 mm is molded. This plate has a wall thickness of 2.0 mm, length of 5.0 mm, width of 10.0 mm
After cutting into pieces and polishing the surface, the refractive index was measured at 25 ° C. with an Abbe refractometer manufactured by Atago Co., Ltd. Further, the glass transition temperature (Tg) of the resin composition was measured with a Du-Pont thermal scanning calorimeter (DSC). The measurement method is from room temperature to 200 ° C at a heating rate of 5 ° C / min.
Up to the first inflection point of the heat energy absorption curve
It was measured as Tg.

[0014]

Example 1 Styrene (St) and 4-vinylbiphenyl (VBP)
Was copolymerized. Methyl ethyl ketone (MEK) was used as the solvent. St / VBP is the composition ratio (parts by weight) of the raw materials.
90/10. 40 parts by weight of MEK, t-
Butyl peroxy-3.5.5-trimethylhexanoate (Trigonox 42: manufactured by Kayaku Akzo) was added at 350 ppm and reacted at a polymerization temperature of 125 ° C until a conversion rate of about 100% by weight was reached.
-4-Vinylbiphenyl copolymer resin was obtained. The obtained polymerization solution was subjected to the above-mentioned treatment, and then a color plate was molded to measure the refractive index and Tg.

[0015]

Example 2 Styrene (St) and 4-vinyl biphenyl (VBP)
Was copolymerized. The composition ratio (parts by weight) of the raw materials was the same as in Example 1 except that the St / VBP was 60/40, respectively. The obtained polymer solution was subjected to the above-mentioned treatment, and then a color plate was molded to measure the refractive index and Tg.

[0016]

Example 3 Styrene (St) and 4-vinyl biphenyl (VBP)
Was copolymerized. The composition ratio (parts by weight) of the raw materials was the same as in Example 1 except that the St / VBP was 40/60, respectively. The obtained polymer solution was subjected to the above-mentioned treatment, and then a color plate was molded to measure the refractive index and Tg.

[0017]

Example 4 Styrene (St) and 4-vinyl biphenyl (VBP)
Was copolymerized. The composition ratio (parts by weight) of the raw materials was the same as in Example 1 except that the St / VBP was 20/80, respectively. The obtained polymer solution was subjected to the above-mentioned treatment, and then a color plate was molded to measure the refractive index and Tg.

[0018]

[Comparative Example 1] The same procedure as in Example 1 was carried out except that 100 parts by weight of styrene (St) and 4-vinylbiphenyl (VBP) were not added. The obtained polymer solution was subjected to the above-mentioned treatment, and then a color plate was molded to measure the refractive index and Tg.

[0019]

[Example 5] Methyl methacrylate (MMA), styrene (S
Terpolymerization of t), 4-vinylbiphenyl (VBP) was performed. Methyl ethyl ketone (MEK) was used as the solvent. The raw material composition ratio was MMA / St / VBP weight ratio of 60/25/15, the polymerization temperature was 125 ° C, MEK was 40 parts by weight based on the total amount of monomer raw materials, and t-butylperoxyisopropyl carbonate was used as an initiator.
(Perbutyl I: manufactured by NOF CORPORATION) was added at 400 ppm. Conversion rate 10
The reaction was carried out to about 0% by weight to obtain a methylmethacrylate-styrene-4-vinylbiphenyl copolymer resin. The obtained polymer solution was subjected to the above-mentioned treatment, and then a color plate was molded to measure the refractive index and Tg.

[0020]

[Comparative Example 2] Copolymerization of methyl methacrylate (MMA) and styrene (St) was performed without adding 4-vinylbiphenyl (VBP). Methyl ethyl ketone (MEK) was used as the solvent. The raw material composition ratio was the same as in Example 5 except that the weight ratio of MMA / St was set to 60/40 to obtain a methyl methacrylate-styrene copolymer resin. The obtained polymer solution was subjected to the above-mentioned treatment, and then a color plate was molded to measure the refractive index and Tg.

[0021]

Example 6 Acrylonitrile (AN), styrene (St), and 4-vinylbiphenyl (VBP) were copolymerized. Methyl ethyl ketone (MEK) was used as the solvent. Raw material composition ratio is AN / St / V
The weight ratio of BP was set to 40/42/18. Polymerization temperature is 14
Performed at 5 ° C. 40 parts by weight of MEK was added to the total amount of monomer raw materials. The reaction was carried out to a conversion of about 100% by weight to obtain an acrylonitrile-styrene-4-vinylbiphenyl copolymer resin composition. The obtained polymer solution was subjected to the above-mentioned treatment and then the color plate was molded to measure the refractive index and Tg.
Summarized in.

[0022]

[Comparative Example 3] Acrylonitrile (AN) and styrene (St) were copolymerized without adding 4-vinylbiphenyl (VBP).
Methyl ethyl ketone (MEK) was used as the solvent. The raw material composition ratio was the same as in Example 6 except that the AN / St weight ratio was 50/50, respectively, to obtain an acrylonitrile-styrene copolymer resin composition. The obtained polymer solution was subjected to the above-mentioned treatment, and then a color plate was molded to measure the refractive index and Tg.

[0023]

Example 7 N-phenylmaleimide (PMI), acrylonitrile (AN), styrene (St), and 4-vinylbiphenyl (VBP) were quaternary copolymerized. Methyl ethyl ketone (MEK) was used as the solvent. The raw material composition ratio was such that the weight ratio of PMI / AN / St / VBP was 20/20/40/20, the polymerization temperature was 125 ° C., and 40 parts by weight of MEK was added to the total amount of the monomer raw materials. Conversion rate 100% by weight
The reaction was conducted to some extent to obtain an N-phenylmaleimide-acrylonitrile-styrene-4-vinylbiphenyl copolymer resin composition. The obtained polymer solution was subjected to the above-mentioned treatment, and then a color plate was molded to measure the refractive index. The results are summarized in Table 1.

[0024]

[Comparative Example 4] Without adding 4-vinylbiphenyl (VBP), N-
Terpolymerization of phenylmaleimide (PMI), acrylonitrile (AN) and styrene (St) was performed. Methyl ethyl ketone (MEK) was used as the solvent. The raw material composition ratio was the same as in Example 7 except that the weight ratio of PMI / AN / St was set to 20/20/60, respectively. The N-phenylmaleimide-acrylonitrile-styrene copolymer resin composition was obtained by reacting up to a conversion rate of about 100% by weight. The obtained polymer solution was subjected to the above-mentioned treatment and then the color plate was molded to measure the refractive index.
Summarized in.

[0025]

Example 8 A ternary copolymerization of α-methylstyrene (αMS), methylmethacrylate (MMA) and 4-vinylbiphenyl (VBP) was performed. Methyl ethyl ketone (MEK) was used as the solvent. The raw material composition ratio is αMS / MMA / VBP weight ratio of 20/60 /
20, the polymerization temperature is 125 ° C, and MEK is added to the total amount of monomer raw materials.
40 parts by weight, t-butyl peroxyisopropyl carbonate (perbutyl I: NOF Corporation) as an initiator to 30 parts by weight
0 ppm was added. The reaction was performed up to a conversion of about 100% by weight to obtain an α-methylstyrene-methylmethacrylate-2-vinylnaphthalene copolymer resin composition. The obtained polymer solution was subjected to the above-mentioned treatment, and then a color plate was molded to measure the refractive index. The results are summarized in Table 1.

[0026]

[Comparative Example 5] α-without adding 4-vinylbiphenyl (VBP)
Copolymerization of methyl styrene (αMS) and methyl methacrylate (MMA) was performed. Methyl ethyl ketone (MEK) was used as the solvent. The raw material composition ratio is 40% for each αMS / MMA weight ratio.
An α-methylstyrene-methylmethacrylate copolymer resin composition was obtained in the same manner as in Example 8 except that the ratio was / 60.
The obtained polymer solution was subjected to the above-mentioned treatment, and then a color plate was molded to measure the refractive index. Table 1 shows the results.

[0027]

[Table 1]

[0028]

EFFECTS OF THE INVENTION According to the present invention described above, a copolymer resin having a high glass transition temperature (heat resistance) and a high refractive index can be obtained, which is suitable as a resin for optical materials such as plastic lenses and prisms. .

Claims (2)

[Claims] 1. A high-heat-resistant optical material characterized by comprising a copolymer obtained by copolymerizing 4-vinylbiphenyl and a radical-polymerizable monomer alone or in combination. Refractive index resin. 2. The high refractive index resin for an optical material having excellent heat resistance according to claim 1, which contains a 4-vinylbiphenyl polymer in a range of 10% by weight or more and 90% by weight or less of the total amount of the resin.