JPH11221834A - Optical prism - Google Patents

Abstract

PROBLEM TO BE SOLVED: To minimize the birefringence and limit a deformation due to environ mental changes by press-molding performs after preliminarily molding a thermo plastic resin with a saturated hydrocarbon ring into the preforms of prism. SOLUTION: Preforms 2a of prism which are of an almost approximate shape to the shape of an article of manufacture are formed by injection-molding an optical thermoplastic resin, preferably a thermoplastic resin with a main chain or a lateral chain having a saturated hydrocarbon ring. Further, these performs 2a are thermally molded under pressure using a specified mold and only the surface layer is melted and further, the prereforms 2a are press-molded to be shaped into prism articles of manufacture. Although the preforms of prism 2a to be obtained by injection molding need not be shaped to the accuracy which is too strict, the extremely inferior accuracy of the face results in the generation of an air pent-up in the surface of moldings during press-molding and the resultant extra labor required for enhancing the face accuracy. For these reasons, it is advisable to reject the preforms 2a with the extremely inferior face accuracy and also obtain the preforms 2a with a press allowance (t) when the preforms 2a are press-molded.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a plastic optical prism and a method for manufacturing the same, and more particularly to a plastic optical prism having a small birefringence, a small deformation with respect to environmental changes such as temperature and humidity, and an optically excellent characteristic. The present invention relates to a plastic optical prism having the same and a method of manufacturing the same.

[0002]

2. Description of the Related Art Cameras or optical branch circuits, optical demultiplexers,
As an optical prism used for an optical device or an optical component such as a multiplexer, an optical switch, an optical modulator, an optical connector, an optical attenuator, and an optical isolator, a glass prism is often used.

However, the glass optical prism has a problem that it is heavy, for example, when it is used for a movable part, a large power is required and power consumption is large, and since it is easily broken, handling is complicated. Since the processing is mainly performed by polishing, long-lasting processing for finishing is required, which results in low productivity and increased cost.

In recent years, a plastic optical prism has been proposed as an alternative to such a glass optical prism.

[0005] In general, plastic is different from glass in that it has advantages such as lightness, high impact resistance, excellent moldability, and low cost. Have been.

Conventionally, thermoplastic optical prisms such as polymethyl methacrylate, polycarbonate, polystyrene, styrene-methyl methacrylate random copolymer (MS) resin, and styrene-acrylonitrile copolymer (AS resin) have been injected as plastic optical prisms. A molded article formed by molding, or a molded article of a thermosetting resin such as diethylene glycol bisallyl carbonate by cast polymerization has been proposed.

[0007]

However, in an optical prism made of a thermoplastic resin manufactured by injection molding, for example, an optical prism made of a polymethyl methacrylate has a problem that the hygroscopic deformation is large and the birefringence of a polycarbonate resin is not reduced. Conventional prisms made of thermoplastic resin are not small in birefringence and small in deformation due to environmental changes, and cannot be used for optical instruments requiring high precision.
In addition, the thermosetting resin optical prism manufactured by casting polymerization has relatively good optical properties such as birefringence, but requires a long polymerization curing time and is inferior in productivity and generates burrs. However, there is a problem that the yield is high and the yield is poor.

The present invention has been made in view of the above circumstances, and provides an optical prism having excellent optical characteristics such as a small birefringence and a small deformation with respect to an environmental change, and a method for manufacturing the same. Aim.

[0009]

In order to achieve the above object, an optical prism according to the present invention comprises: a preform of a thermoplastic resin having a saturated hydrocarbon ring; It is characterized by being obtained by press-molding a molded body.

As the thermoplastic resin, an optical prism obtained by press molding using a thermoplastic resin having a saturated hydrocarbon ring has a small birefringence.
The present inventor has found that the optical characteristics are excellent such as small deformation due to environmental change, and that the surface accuracy can be improved by selecting appropriate molding conditions. In this specification, the “optical prism” refers to an optical element having two or more flat surfaces and transmitting and refracting light, and may have various shapes, for example, a prism. A multifunctional product having the function of a lens in addition to the function is also included.

In the optical prism according to the present invention, the thermoplastic resin is preferably a thermoplastic resin having a saturated hydrocarbon ring in a main chain or a side chain, particularly preferably a thermoplastic nobornene resin.

[0012] The method of manufacturing an optical prism according to the present invention comprises:
By injection molding thermoplastic resin, etc., a prism preform is formed slightly larger than the product shape in the direction perpendicular to one surface of the prism and slightly smaller than the product shape in the direction parallel to the same surface. The product is obtained by press-molding the body.

In the present invention, the preform can be molded by injection molding, extrusion molding or the like, but is preferably molded by injection molding since a desired shape can be obtained with high productivity. In the present invention, the dimensions of the preform are such that the volume of the preform and the volume of the product are substantially the same (preferably -3% to + 3%, more preferably -1%).
+ 1%), and is slightly larger than the product shape in the direction perpendicular to one surface of the prism (pressing direction) and slightly smaller than the product shape in the direction parallel to the same surface. Preferably.

In the method for manufacturing an optical prism according to the present invention, the lower limit of the pressing pressure at the time of press molding is not particularly limited depending on the kind of the thermoplastic resin, but is preferably 10 kgf / cm ² or more, and more preferably. Is 2
5 kgf / cm ² or more. Further, the upper limit of the pressing pressure at the time of press molding is not particularly limited by the kind of the thermoplastic resin or the like, but is preferably 200 kgf / c.
m ² or less, more preferably 150 kgf / cm ² or less. The lower limit of the press pressure is determined so that good press molding is performed, and the upper limit of the press pressure is determined by restrictions on the equipment of the mold.

In the method for manufacturing an optical prism according to the present invention, the maximum temperature during press molding is not particularly limited, but is preferably from (Tg + 20) ° C. to the glass transition temperature (Tg) of the thermoplastic resin. (Tg + 90)
° C, more preferably (Tg + 30) ° C to (Tg +
80) carried out under the condition of ° C. If the maximum temperature during press molding is too high, there is a tendency for foaming and burrs to occur due to the decomposition gas, and if it is too low, there is a tendency for air pockets to be generated or for defoaming to occur, and for the area to decrease.

Generally, 500 to 190 in injection molding.
0 kgf / cm ² , Tg + 100 ° C to Tg + 250 °
While the molding conditions of about C are used, the press molding in the present invention is performed by melting only the surface layer portion of the preformed product under lower pressure and lower temperature conditions. Pressure is uniformly applied to the entire surface of the product,
A product with excellent surface properties can be obtained.

In the method for manufacturing an optical prism according to the present invention, at least one surface of the preform before press molding may be subjected to a roughening treatment or a polishing treatment. By performing the surface roughening treatment, the sliding characteristics with the mold for press molding are improved, and the air accumulation on the surface of the obtained prism product is reduced. Further, by polishing the preform, the surface accuracy of the surface of the obtained prism product is improved.

The means for performing the surface roughening treatment is not particularly limited, but the rough surface formed on the inner peripheral surface of the cavity of the mold for molding the preform is formed on the surface of the preform. Examples of the method include a transfer method and a sandblasting method. The polishing method is not particularly limited, and examples thereof include polishing using a flat file and polishing with an abrasive.

In the method for manufacturing an optical prism according to the present invention, the preform before press molding may be annealed. The temperature for the annealing treatment is not particularly limited, but the glass transition temperature (T
g), preferably (Tg-60) ° C to (Tg
+20) ° C, more preferably (Tg-40) ° C
It is performed under the condition of (Tg + 10) ° C. If the temperature for the annealing treatment is too high, the area tends to deteriorate,
If it is too low, the birefringence tends not to be sufficiently small. By performing the annealing treatment, the optical characteristics are improved, for example, the birefringence of the prism product is reduced. However, since the surface accuracy tends to be reduced by annealing, it is preferable to polish the preformed body after the annealing. Polishing the preform improves surface accuracy of the surface of the obtained prism product.

In the method of manufacturing an optical prism according to the present invention, the press pressure P3 during the cooling step during press molding is used.
Is the pressing pressure P0 in the temperature raising step during press molding.
Preferably, it is higher than the above. By increasing the pressing pressure in the cooling step, air accumulation on the surface of the obtained prism product is reduced. P3-P0 is not particularly limited,
20 to 170 kgf / cm ² is preferred. In the present invention, if necessary, the pressing pressure P0 in the temperature raising step during press molding may be higher than the pressing pressure P3 in the cooling step during press molding.

In the method for manufacturing an optical prism according to the present invention, the cooling step during press molding is performed by flowing an inert gas such as nitrogen gas at a predetermined temperature into a mold while applying a pressing pressure. It is preferred to do so. The cooling rate can be controlled by the temperature and the flow rate of the gas. In the method of the present invention, the cooling rate is not particularly limited, but the temperature of the product is preferably (6.0 × 10 ^{-2 to} 6.
0 × 10 ⁻¹ ) ° C./sec, particularly preferably (8.0 × 10 ⁻¹ ) ° C./sec.
^{-2 to} 2.0 × 10 ⁻¹ ) ° C./sec. If the cooling rate is too fast, air accumulation tends to occur on the surface of the product, and if the cooling rate is too slow, the time until the product is removed from the press mold is undesirably long.

In the present invention, the mold used for press molding is not particularly limited.
It is not limited to metals such as carbon steel and cemented carbide, but may be made of glass, ceramic, a composite of epoxy and aluminum, and the like. It is preferable that the mold is provided with a heating means such as a heat medium pipe, an infrared heater and a cartridge heater, and a cooling means such as an inert gas supply means and a refrigerant pipe.

[0023]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail based on embodiments.

Having a saturated hydrocarbon ring in the main chain or side chain
The optical prism according to the present embodiment is formed of a thermoplastic resin having a saturated hydrocarbon ring in a main chain or a side chain.

Examples of the thermoplastic resin having a monocyclic saturated hydrocarbon ring in the main chain or side chain include a thermoplastic norbornene resin, a vinyl cyclic hydrocarbon polymer, and a cyclic conjugated diene addition polymer. You.

Thermoplastic norbornene-based resin The thermoplastic norbornene-based resin usable in the present embodiment is disclosed in JP-A-3-14882 and JP-A-3-1221.
It is a known resin disclosed in, for example, Japanese Patent Publication No. 37-37. Specifically, a hydrogenated product of a ring-opening polymer of a norbornene-based monomer, an addition-type polymer of a norbornene-based monomer, an addition-type copolymer of a norbornene-based monomer and an olefin,
And modified products of these polymers.

The norbornene-based monomers are described in the above publications, JP-A-2-227424 and JP-A-2-27684.
It is a known monomer disclosed in, for example, JP-A No. 2 (Kokai) Publication.
Specifically, for example, polycyclic hydrocarbons having a norbornene structure; substituted derivatives thereof such as alkyl, alkenyl, alkylidene, and aromatic; halogens, hydroxyl groups, ester groups,
Polar group-substituted derivatives such as alkoxy group, cyano group, amide group, imide group and silyl group; substituted derivatives of these polar groups such as alkyl, alkenyl, alkylidene and aromatic. Among them, polycyclic hydrocarbons having a norbornene structure and substituted derivatives thereof such as alkyl, alkenyl, alkylidene, and aromatic are particularly excellent in chemical resistance and moisture resistance and are suitable. Specifically, the following norbornene-based monomers can be exemplified.

Specific examples of the norbornene-based monomer include, for example, 5-methyl-2-norbornene, 5,5-
Dimethyl-2-norbornene, 5-ethyl-2-norbornene, 5-butyl-2-norbornene, 5-ethylidene-2-norbornene, 5-methoxycarbonyl-2-norbornene, 5-cyano-2-norbornene, 5-methyl- 5-methoxycarbonyl-2-norbornene, 5-phenyl-2-norbornene, 5-phenyl-5-methyl-2-norbornene and the like; dicyclopentadiene, substituted derivatives thereof and the like, for example, 2,3-dihydrodiene Cyclopentadiene and the like; dimethanooctahydronaphthalene, substituted derivatives thereof as described above, and the like, for example, 6-methyl-1,4: 5,8-dimethano-1,4,4a, 5
6,7,8,8a-octahydronaphthalene, 6-ethyl-1,4: 5,8, dimethano-1,4,4a, 5
6,7,8,8a-octahydronaphthalene, 6-ethylidene-1,4: 5,8, dimethano-1,4,4a,
5,6,7,8,8a-octahydronaphthalene, 6-
Chloro-1,4: 5,8, dimethano-1,4,4a,
5,6,7,8,8a-octahydronaphthalene, 6-
Cyano-1,4: 5,8-dimetano-1,4,4a,
5,6,7,8,8a-octahydronaphthalene, 6-
Pyridyl-1,4: 5,8-dimetano-1,4,4a,
5,6,7,8,8a-octahydronaphthalene, 6-
Methoxycarbonyl-1,4: 5,8-dimetano-1,
4,4a, 5,6,7,8,8a-octahydronaphthalene and the like; adducts of cyclopentadiene and tetrahydroindene and the like, substituted derivatives thereof as described above, and the like,
1,4-dimethano-1,4,4a, 4b, 5,8,8
a, 9a-octahydrofluorene, 5,8-methano-
1,2,3,4,4a, 5,8,8a-octahydro-
2,3-cyclopentadienonaphthalene and the like; multimers of cyclopentadiene, substituted derivatives thereof and the like, such as 4,9: 5,8-dimethano-3a, 4,4a,
5,8,8a, 9,9a-octahydro-1H-benzoindene, 4,11: 5,10: 6,9-trimethano-
3a, 4,4a, 5,5a, 6,9,9a, 10,10
a, 11,11a-dodecahydro-1H-cyclopentaanthracene; and the like.

These norbornene monomers can be used alone or in combination of two or more. The ratio of the norbornene-based monomer binding amount of the monomer in the thermoplastic norbornene-based resin is appropriately selected according to the purpose of use, but is usually 30% by weight or more, preferably 50% by weight or more, more preferably 70% by weight or more. In some cases, the heat resistance is high, which is preferable.

Examples of the copolymerizable vinyl compound include ethylene, propylene, 1-butene, 1-pentene, 1-hexene, 3-methyl-1-butene, 3-methyl-1-pentene and 3-ethyl- 1-pentene, 4-methyl-1-pentene, 4-methyl-1-hexene, 4,
4-dimethyl-1-hexene, 4,4-dimethyl-1-
Pentene, 4-ethyl-1-hexene, 3-ethyl-1
-Hexene, 1-octene, 1-decene, 1-dodecene, 1-tetradecene, 1-hexadecene, 1-octadecene, 1-eicosene and the like, ethylene or α-olefin having 2 to 20 carbon atoms; cyclobutene, cyclopentene, cyclohexene, 3,4-dimethylcyclopentene, 3-methylcyclohexene, 2- (2-methylbutyl) -1-cyclohexene, cyclooctene, 3a,
5,6,7a-tetrahydro-4,7-methano-1H-
Cycloolefins such as indene; 1,4-hexadiene, 4-methyl-1,4-hexadiene, 5-methyl-
Non-conjugated dienes such as 1,4-hexadiene and 1,7-octadiene; These vinyl compounds can be used alone or in combination of two or more.

The polymerization method and hydrogenation method of the norbornene monomer or the vinyl compound copolymerizable with the norbornene monomer are not particularly limited, and can be carried out according to known methods. Further, the obtained polymer or polymer hydrogenated product is subjected to a known method disclosed in JP-A-3-95235 or the like to obtain an α, β-unsaturated carboxylic acid and / or a derivative thereof, a styrene-based hydrocarbon, It may be modified using an organosilicon compound having an olefinically unsaturated bond and a hydrolyzable group, an unsaturated epoxy monomer, or the like.

The molecular weight of the thermoplastic norbornene resin is as follows:
Although it is appropriately selected according to the purpose of use, the intrinsic viscosity [η] measured in decalin at 80 ° C. is usually 0.01 to 20 dl.
/ G, preferably 0.1 to 10 dl / g, more preferably 0.2 to 5 dl / g, most preferably 0.3 to 1 dl.
/ G range. If the intrinsic viscosity [η] of the thermoplastic norbornene resin is too small, the mechanical strength is not sufficient,
On the other hand, if it is excessively large, the moldability is not sufficient, and both are not preferred.

The molecular weight distribution of the thermoplastic norbornene-based resin is not particularly limited, but the weight average molecular weight (Mw) and the number average molecular weight (Mn) in terms of polystyrene by gel permeation chromatography (GPC) using toluene as a solvent. When the ratio (Mw / Mn) is usually 4.0 or less, preferably 3.0 or less, and more preferably 2.5 or less, the mechanical strength is highly enhanced, which is suitable.

The glass transition temperature (Tg) of the thermoplastic norbornene resin may be appropriately selected, but is usually 50 to
A range of 300 ° C., preferably 100 to 250 ° C., and more preferably 120 to 200 ° C. is suitable because heat resistance and moldability are highly balanced.

Vinyl Cyclic Hydrocarbon Polymer The vinyl cyclic hydrocarbon polymer is not particularly limited, but (A) a hydrogenated product of an aromatic vinyl compound or a substituted polymer thereof, and (B) a vinylcyclohexene polymer The compound is preferably a polymer of a compound and / or a vinylcyclohexane-based compound or a hydrogenated product thereof.

The vinyl-based cyclic hydrocarbon-based monomer used for obtaining the vinyl-based cyclic hydrocarbon-based polymer includes:
For example, styrene, α-methylstyrene, α-ethylstyrene, α-propylstyrene, α-isopropylstyrene, α-t-butylstyrene, 2-methylstyrene,
3-methylstyrene, 4-methylstyrene, 2,4-diisopropylstyrene, 2,4-dimethylstyrene,
Styrene-based monomers such as -t-butylstyrene, 5-t-butyl-2-methylstyrene, monochlorostyrene, dichlorostyrene, monofluorostyrene and 4-phenylstyrene; vinylcyclohexane, 3-methylisopropenylcyclohexane and the like Vinylcyclohexane monomer; 4-vinylcyclohexene, 4-isopropenylcyclohexene, 1-methyl-4-vinylcyclohexene, 1-methyl-4-isopropenylcyclohexene, 2-methyl-4-vinylcyclohexene, 2-methyl- Vinylcyclohexene-based monomers such as 4-isopropenylcyclohexene; d-terpene, 1-terpene,
Examples include a vinylated six-membered ring hydrocarbon-based monomer such as a terpene-based monomer such as diterpene, or a substituted product thereof. When a styrene monomer containing an aromatic ring is used, the hydrogenation rate is preferably adjusted to 80% or more by a hydrogenation reaction.

In the present embodiment, a monomer other than the above-mentioned monomers may be copolymerized within a range where the repeating unit in the polymer is less than 50% by weight. The copolymerizable monomer is not particularly limited as long as it can be copolymerized in a polymerization method such as radical polymerization, anionic polymerization, or cationic polymerization. Examples thereof include ethylene, propylene, isobutene, and 2-methyl-1-. Α-olefin monomers such as butene, 2-methyl-1-pentene and 4-methyl-1-pentene; cyclopentadiene, 1-methylcyclopentadiene, 2-methylcyclopentadiene, 2-ethylcyclopentadiene, 5- Cyclopentadiene monomers such as methylcyclopentadiene and 5,5-dimethylcyclopentadiene; cyclic olefin monomers such as cyclobutene, cyclopentene, cyclohexene and dicyclopentadiene; butadiene, isoprene, 1,
Conjugated diene monomers such as 3-pentadiene, furan, thiophene, and 1,3-cyclohexene; Nitrile monomers such as acrylonitrile, methacrylonitrile, α-chloroacrylonitrile; methyl methacrylate, ethyl methacrylate , Propyl methacrylate, butyl methacrylate, methyl acrylate, ethyl acrylate,
(Meth) acrylate monomers such as propyl acrylate and butyl acrylate; unsaturated fatty acid monomers such as acrylic acid, methacrylic acid and maleic anhydride; phenylmaleimide; ethylene oxide and propylene oxide , Trimethylene oxide, trioxane, dioxane, cyclohexene oxide, styrene oxide, epichlorohydrin, tetrahydrofuran and other cyclic ether-based monomers; methyl vinyl ether, N-vinylcarbazole, and heterocyclic-containing vinyl compounds such as N-vinyl-2-pyrrolidone Monomer; and the like. Generally, when the content of the repeating unit derived from a monomer other than the vinyl-based cyclic hydrocarbon monomer increases, the transparency of the polymer decreases.

The content of the repeating unit of the vinyl cyclic hydrocarbon monomer or a substituted product thereof is appropriately selected according to the purpose of use, but is usually 50% by weight or more, preferably 70% by weight or more.
% Or more, more preferably 80% or more, most preferably 90% or more.

The hydrogenation rate of the aromatic ring or cyclohexene ring is 80% or more, preferably 90% or more, more preferably 95% or more. If the hydrogenation rate is too low, the birefringence is poor, which is not preferable. Incidentally, the hydrogenation rate can be determined by ¹ H-NMR measurement.

In the present embodiment, the weight average molecular weight (Mw) of the vinyl cyclic hydrocarbon polymer is generally 10,000 to 10,000 in terms of polystyrene measured by GPC.
1,000,000, preferably 50,000 to 50
0000, more preferably 100,000-300,
000, and the molecular weight distribution is usually 5 as the ratio (Mw / Mn) of the weight average molecular weight (Mw) and the number average molecular weight (Mn) in terms of polystyrene measured by gel permeation chromatography (GPC). 0.0 or less, preferably 3.0 or less, more preferably 2.5 or less, and most preferably 2.0 or less. When Mw / Mn of the vinyl cyclic hydrocarbon polymer is in the above range, the mechanical strength and heat resistance of the polymer are particularly excellent, and when the weight average molecular weight (Mw) is in the above range, the strength characteristics of the polymer and molding The properties and the birefringence are balanced.

In the case of a hydrogenated product, if the weight average molecular weight (Mw) of the unhydrogenated polymer is excessively large, the hydrogenation reaction of the ring is difficult, and the hydrogenation reaction is forcibly advanced to nearly 100%. The molecular chain distribution reaction, which is a competitive reaction, progresses and the molecular weight distribution increases, and the low molecular weight component increases, so the strength characteristics and heat resistance decrease.On the contrary, if it is excessively small, the strength characteristics are inferior and the molding is insufficient. Since the product can not be molded, none of them is preferable, when it is in the above range, the mechanical strength,
It is suitable because the heat resistance and the like are highly balanced.

The method for producing the vinyl-based cyclic hydrocarbon polymer of the present embodiment is obtained by polymerizing using a known polymerization method such as radical polymerization, anion polymerization, anion living polymerization, cation polymerization, and cation living polymerization.

As the polymerization method, in the case of radical polymerization, polymerization can be performed by a known method using an organic peroxide, and in the case of cationic polymerization, polymerization can be performed by a known method using BF ₃ , PF ₆ or the like.

In order to obtain a polymer having a small molecular weight distribution, it is preferable to carry out polymerization by anionic living polymerization. Specifically, it can be easily obtained by polymerization in a hydrocarbon solvent using an organic alkali metal as an initiator. .

The polymerization methods include bulk polymerization, emulsion polymerization,
Although suspension polymerization, solution polymerization and the like can be applied, solution polymerization is preferable in order to continuously carry out the hydrogenation reaction.

Cyclic conjugated diene-based addition polymer The cyclic conjugated diene-based addition polymer is not particularly limited, but includes 1,3-cyclopentadiene, 1,3-cyclohexadiene, 1,3-cycloheptadiene, 1,3-cyclopentadiene and 1,3-cyclopentadiene. Examples include hydrides of polymers and copolymers of cyclic conjugated dienes having a 5- to 8-membered carbon ring such as cyclooctadiene.

Other monomers copolymerizable with the cyclic conjugated diene having a 5- to 8-membered carbon ring include 1,3-butadiene, isoprene, 2,3-dimethyl-1,3-butadiene, 1,3 Chain conjugated diene monomers such as pentadiene and 1,3-hexadiene, styrene, α-methylstyrene, o-methylstyrene, p-methylstyrene, p-
vinyl aromatic monomers such as tert-butylstyrene, 1,3-dimethylstyrene, divinylbenzene, vinylnaphthalene, diphenylethylene, and vinylpyridine, methyl methacrylate, methyl acrylate, acrylonitrile, methyl vinyl ketone, α-cyano Examples thereof include polar vinyl monomers such as methyl acrylate, and polar monomers such as ethylene oxide, propylene oxide, cyclic tecton, and cyclic lactam cyclic siloxane, and ethylene monomers and α-olefin monomers. The proportion of these copolymerizable monomers is at most 60% by weight, preferably at most 50% by weight.

As the hydrogenation method and the hydrogenation catalyst for the above-mentioned polymer and copolymer of the cyclic conjugated diene having a 5- to 8-membered carbon ring, known ones can be employed.

The molecular weight of the hydride is usually 5,000 to 1,000,000 as the average molecular weight in terms of polystyrene measured by the GPC method of a 1,2,4-trichlorobenzene solution.
000, preferably 10,000 to 500,000.

Preferred thermoplastic resins The thermoplastic resins having a saturated hydrocarbon ring in the main chain or side chain as exemplified above can be used alone or in combination of two or more as necessary.
Among these thermoplastic resins having a saturated hydrocarbon ring in the main chain or side chain, when it is desired to obtain a product having an extremely low birefringence as an optical prism, among the various resins exemplified above, a vinyl-based cyclic resin may be used. Hydrocarbon polymers are preferred, and norbornene-based resins are preferred in terms of the balance between product strength and low birefringence. Among them, norbornene-based resins are particularly preferred because they provide products with excellent moldability and low birefringence. A hydrogenated product of a ring-opening polymer of a monomer, an addition polymer of a norbornene monomer, and an addition copolymer of a norbornene monomer and an olefin are preferable.

Optional Ingredients The thermoplastic resin having a saturated hydrocarbon ring in the main chain or side chain used in manufacturing the optical prism according to the present embodiment may contain various compounding agents, if necessary. Can also be added. However, from the viewpoint of obtaining a product having excellent optical properties, it is desirable not to add a compounding agent as much as possible. As compounding agents, anti-aging agents, stabilizers, flame retardants, not high molecular weight compounding agents such as plasticizers, organic polymer compounds that are unlikely to cause elution,
Organic oligomer components are preferred, and rubbery polymers are particularly preferred.

Rubbery Polymer The rubbery polymer is a polymer having a glass transition temperature (Tg) of 0 ° C. or lower, and includes ordinary rubbery polymers and thermoplastic elastomers. The Mooney viscosity (ML1 + 4, 100 ° C.) of the rubbery polymer is appropriately selected depending on the purpose of use, and is usually 5 to 200.

Examples of the rubbery polymer include isoprene.
Rubber, hydrogenated product thereof; chloroprene rubber, hydrogenated product thereof; ethylene / propylene copolymer, ethylene / α-
Saturated polyolefin rubber such as olefin copolymer, propylene / α-olefin copolymer; ethylene / propylene / diene copolymer, α-olefin / diene copolymer, diene copolymer, isobutylene / isoprene copolymer, isobutylene Diene polymers such as diene copolymers, halides thereof, diene polymers or hydrogenated products thereof; acrylonitrile / butadiene copolymers, hydrogenated products thereof; vinylidene fluoride / ethylene trifluoride Fluororubber such as copolymer, vinylidene fluoride / propylene hexafluoride copolymer, vinylidene fluoride / propylene hexafluoride / ethylene tetrafluoride copolymer, and propylene / tetrafluoroethylene copolymer; urethane rubber; Silicone rubber, polyether rubber, acrylic rubber, chlorsulfonated Special rubbers such as polyethylene rubber, epichlorohydrin rubber, propylene oxide rubber, and ethylene acrylic rubber; terpolymers of norbornene monomers and ethylene or α-olefins, and terpolymers of norbornene monomers and ethylene and α-olefins Norbornene-based rubbery polymers such as coalesced polymers, ring-opened polymers of norbornene-based monomers, and ring-opened polymers of norbornene-based monomers; styrene-butadiene-rubber, high-styrene rubber, emulsion- or solution-polymerized Random or block styrene / butadiene copolymers such as styrene / butadiene / styrene rubber, styrene / butadiene / styrene / rubber, styrene / isoprene / styrene / rubber, and aromatic vinyl such as styrene / ethylene / butadiene / styrene / rubber Copolymerization of terpolymer monomers and conjugated dienes Bodies, their hydrogenated products; styrene butadiene styrene rubber,
Styrene-based thermoplastic elastomers such as linear or radial block copolymers of aromatic vinyl monomers and conjugated dienes such as styrene, isoprene, styrene, rubber, styrene, ethylene, butadiene, styrene, rubber, etc., and their hydrogenated products , Urethane-based thermoplastic elastomers, polyamide-based thermoplastic elastomers, 1,2-
Examples thereof include thermoplastic elastomers such as a polybutadiene-based thermoplastic elastomer, a vinyl chloride-based thermoplastic elastomer, and a fluorine-based thermoplastic elastomer.

Of these, copolymers of an aromatic vinyl monomer and a conjugated diene monomer, and hydrogenated products thereof, generally have good dispersibility with the resin as the main component, and are preferred in that respect. . The copolymer of the aromatic vinyl monomer and the conjugated diene monomer may be a block copolymer or a random copolymer. From the viewpoint of weather resistance, those in which a portion other than the aromatic ring is hydrogenated are more preferable. In particular,
Styrene / butadiene block copolymer, styrene / butadiene / styrene / block copolymer, styrene / isoprene / block copolymer, styrene / isoprene /
Styrene block copolymers and their hydrogenated products, styrene / butadiene random copolymers and their hydrogenated products are exemplified.

In the present embodiment, the thermoplastic resin having a saturated hydrocarbon ring in the main chain or side chain as the main component is
Addition of the rubbery polymer as described above is preferable because, for example, even under high-temperature and high-humidity conditions, the resulting cylindrical molded product is less likely to be clouded and maintains high transparency.

[0056] Other organic polymeric compounds other organic polymer compound, for example, low density polyethylene, high density polyethylene, linear low density polyethylene, ultra low density polyethylene, polypropylene, poly-4-methyl - pentene-1 , Polyolefin polymers such as cyclic olefin polymers; copolymers of olefins with other monomers such as ethylene-ethyl acrylate copolymer and ethylene-vinyl acetate copolymer; styrene polymers such as polystyrene (Meth) acrylic polymers such as polymethyl methacrylate and cyclohexyl methacrylate-methyl methacrylate copolymer; polyether polymers such as polyphenylene sulfide, polyphenylene ether, and polysulfone; liquid crystal plastic, aromatic polyester, and polyarylate , Polyethylene terephthalate, polybutylene terephthalate, polycarbonate, polyether ether ketone, polyether ketone which polyester polymers and the like; polyacrylonitrile, polyamide, polyacrylonitrile styrene (AS resin), polymethyl methacrylate styrene (M
S resin).

These rubbery polymers and other organic high molecular compound resins can be used alone or in combination of two or more. The compounding amount is within a range not to impair the object of the present embodiment. It is appropriately selected.

Partial ether compound and partial esterification
In the compound or the present embodiment, in order to prevent clouding in the obtained optical prism, at least one alcoholic hydroxyl group and an organic compound having at least one ether bond, or at least one alcoholic hydroxyl group, A cyclic hydrocarbon having a monocyclic ring structure in the main chain or side chain as a main component, in place of, or together with, the rubbery polymer, the organic compound having at least one ester bond as described above. It is also possible to mix it with resin. However, as described above, since there is little possibility that elution or the like occurs, it is desirable to use a rubbery polymer from the viewpoint of imparting the effect of preventing white turbidity.

At least one alcoholic hydroxyl group,
The organic compound having at least one ether bond is not particularly limited as long as it is an organic compound having at least one alcoholic hydroxyl group other than a phenolic hydroxyl group and at least one ether bond unit in the molecule. However, for example, a dihydric or higher polyhydric alcohol, more preferably a trihydric or higher polyhydric alcohol, still more preferably 3 to
A partial ether compound in which at least one of the hydroxyl groups is etherified, such as a polyhydric alcohol having eight hydroxyl groups, may be used.

The organic compound having at least one alcoholic hydroxyl group and at least one ester bond includes at least one alcoholic hydroxyl group that is not a phenolic hydroxyl group and an ester bond unit in the molecule. Is not particularly limited as long as it is an organic compound having at least one polyhydric alcohol, for example, a dihydric or higher polyhydric alcohol, more preferably a trihydric or higher polyhydric alcohol, and still more preferably a polyhydric alcohol having 3 to 8 hydroxyl groups. And a partial ester compound in which at least one of the hydroxyl groups is esterified.

Examples of the dihydric or higher polyhydric alcohol include polyethylene glycol, glycerol, trimethylolpropane, pentaerythritol, diglycerol, triglycerol, dipentaerythritol,
6,7-trihydroxy-2,2-di (hydridoxymethyl) -4-oxoheptane, sorbitol, 2-methyl-1,6,7-trihydroxy-2-hydroxymethyl-4-oxoheptane, 1, 5,6-trihydroxy-
Examples thereof include 3-oxohexanepentaerythritol, dipentaerythritol, and tris (2-hydroxyethyl) isocyanurate. Among them, particularly, trihydric or higher polyhydric alcohols, and polyhydric alcohols having 3 to 8 hydroxyl groups are particularly preferable. Polyhydric alcohols are preferred. When a partially esterified product is obtained, glycerol, diglycerol, triglycerol, etc., which can synthesize a partial ester compound containing α, β-diol, are preferred.

The substituents used for etherification or esterification are not particularly limited, but are preferably those having 4 to 100 carbon atoms, preferably 4 to 30 carbon atoms, and 8 carbon atoms.
~ 22 are particularly preferred. Preferred specific examples include a linear or branched alkyl group having 4 to 30 carbon atoms, an alkylene group, an aryl group having 6 to 30 carbon atoms, and an arylene group. If the carbon number is too small, it tends to volatilize, and bleeding tends to occur in the molded product. If the carbon number is too large, the compatibility with the vinyl-based cyclic hydrocarbon polymer will be poor.

In the etherification reaction, a halide, an epoxide or an aldehyde having these substituents is reacted with the above-mentioned polyhydric alcohol. In the esterification reaction, a carboxylic acid having these substituents is used. , Acid anhydrides, etc., with the above-mentioned polyhydric alcohols.

In the case of etherification, a compound obtained by condensing a phenol with an aldehyde and / or a ketone, a hydrogenated product of the condensate, and an unsaturated hydrocarbon such as a phenol and a diolefin are used. May be used as a compound condensed by a Friedel-Crafts reaction, a hydrogenated product of the condensate, a mixture of two or more of these. In these compounds, a novolak-type condensed residue having 13 to 100 carbon atoms, preferably 15 to 75 carbon atoms, more preferably 13 to 30 carbon atoms, or a hydrogenated compound thereof is usually used as a substituent for etherification. Can be Among them, those having a condensation degree of 4 or less are preferable. If the degree of condensation is too large, the compatibility will be poor. The preferred degree of condensation is 1.5 to 4.0 on average for the molecules in the condensate. Examples of the phenols include phenol, butylphenol, octylphenol, nonylphenol, and cresol.Examples of the aldehydes include formaldehyde, acetaldehyde, propionaldehyde, and butylaldehyde.Examples of the ketones include acetone and methyl-ethyl-ketone. , Methyl-isobutyl ketone, cyclohexanone, acetophenone and the like. As diolefins, butadiene, isoprene, 1,3
-Pentadiene, dicyclopentadiene and the like.

Examples of condensates of phenols and aldehydes and / or ketones include phenols such as condensates of p-nonylphenol and formaldehyde, condensates of p-octylphenol and formaldehyde, and condensates of p-octylphenol and acetone. Examples of the condensate of phenol and diolefins include a condensate of p-octylphenol and dicyclopentadiene. The etherified product of such a condensate can be obtained not only by actually condensing but also by hydrolyzing a cresol novolak type epoxy resin.

Specific examples of such partially etherified and partially esterified products include glycerin monostearate, glycerin monolaurate, glycerin monobehenate, diglycerin monostearate, glycerin distearate, glycerin dilaurate, and the like. Etherified products of polyhydric alcohols such as pentaerythritol monostearate, pentaerythritol monolaurate, pentaerythritol monobeherate, pentaerythritol distearate, pentaerythritol dilaurate, pentaerythritol tristearate, dipentaerythritol distearate; -(Octyloxy) -1,2-propanediol, 3- (decyloxy) -1,2-propanediol, 3- (lauryloxy) -1,2- Propanediol, 3- (4-nonyl-yl-phenyl) -1,2-propanediol, 1,
6-dihydroxy-2,2-di (hydroxymethyl)-
7- (4-nonylphenyloxy) -4-oxoheptane, an ether compound obtained by reacting a condensate of p-nonylphenol and formaldehyde with glycidol,
an ether compound obtained by reacting a condensate of p-octylphenol and formaldehyde with glycidol, p
Esterified products of polyhydric alcohols such as ether compounds obtained by the reaction of glycidol with a condensate of octylphenol and dicyclopentadiene.

The molecular weight of the etherified product or esterified product of these polyhydric alcohols is not particularly limited.
Those having a molecular weight of from 00 to 2000, preferably from 800 to 1500 are preferable because they are hardly eluted and a decrease in transparency is small. These etherified or esterified polyhydric alcohols are used alone or in combination of two or more, and the compounding amount is appropriately selected within a range that does not impair the purpose of the present embodiment.

Other Compounds In the present embodiment, if necessary, compounding agents usually used in the resin industry can be compounded. Examples of the compounding agent include a stabilizer, a crystal nucleating agent, an antistatic agent, a lubricant, an antiblocking agent, and a flame retardant.

Examples of the stabilizer include phenol-based antioxidants, phosphorus-based antioxidants, and sulfur-based antioxidants. Of these, phenol-based antioxidants are preferable, and alkyl-substituted phenol-based antioxidants are preferred. Agents are particularly preferred.

These antioxidants are each used alone.
Alternatively, two or more kinds can be used in combination.
The amount of the antioxidant is usually 0.001 to 5 parts by weight, preferably 0.01 to 5 parts by weight, per 100 parts by weight of the thermoplastic resin.
The range is 1 part by weight.

Examples of the crystal nucleating agent include salts of benzoic acid, dibenzylidene sorbitols, salts of phosphoric acid esters, and polymers having a high melting point such as polyvinylcyclohexane, poly-3-methylbutene, crystalline polystyrene and trimethylvinylsilane. Is preferred, and
Inorganic compounds such as talc, kaolin and mica can also be preferably used. These nucleating agents can be used alone or in combination of two or more. When used, the amount is usually 0.0001 to
It is in the range of 1% by weight.

Examples of the antistatic agent include sodium alkylsulfonate and / or phosphonium alkylsulfonate, and fatty acid ester hydroxyamine compounds such as glycerin ester of stearic acid. These antistatic agents can be used alone or in combination of two or more. When added, the amount of the antistatic agent is usually in the range of 0 to 5 parts by weight based on 100 parts by weight of the thermoplastic resin.

[0073] The method of adding these additives compounded compounding agents, compounding agents so long as it is a method for sufficiently dispersed so as not to lower the light transmittance in the resin is not particularly limited. For example, a method of adding and kneading a compounding agent in a state where a resin is melted by a mixer, a single-screw kneader, a twin-screw kneader, or a method of dissolving a compounding agent in an appropriate solvent and dispersing the compounding agent, a coagulation method, and a casting method. Or a method of removing the solvent by a direct drying method.

In the case of kneading, generally, assuming that the glass transition temperature of the resin is Tg, Tg + 20 ° C. to Tg + 15
At a resin temperature of 0 ° C, a sufficient share is applied. If the resin temperature is too low, the viscosity increases and kneading is difficult. If the temperature is too high, the resin and the compounding agent deteriorate, and the two cannot be kneaded well due to differences in viscosity and melting point.

From the viewpoint of improving the transparency of the molded product, it is preferable that the difference in the refractive index between the compounding agent and the resin is small. The difference in the refractive index is preferably 0.2 or less, more preferably 0.1 or less, and particularly preferably 0.05 or less. Particularly when transparency is required, it is generally 0.02 or less, preferably 0.015 or less, more preferably 0.02 or less.
The difference in refractive index is 1 or less. Mixing those having a large difference in refractive index tends to be opaque when added in a large amount. Different types of thermoplastic resins have different refractive indices,
For example, the refractive index of a rubbery polymer can be changed continuously by changing the ratio of monomers or changing the number of unsaturated bonds in the main chain by hydrogenation or the like. It is preferable to select a rubbery polymer having an appropriate refractive index according to the refractive index of the thermoplastic resin used.

Method of Manufacturing Optical Prism The method of manufacturing an optical prism according to the present embodiment comprises pressing an optical thermoplastic resin, preferably a thermoplastic resin having a saturated hydrocarbon ring in the main chain or side chain as described above. It is to be molded. More specifically, first, as shown in FIG. 2, a prism preform 2a having a shape substantially similar to the product shape is molded by injection molding using a thermoplastic resin. Next, the prism preform 2a thus obtained is heated and pressed using, for example, predetermined molds 4 and 6 as shown in FIG. Then, it is shaped into the shape of the prism product 2 shown in FIG.

The prism preform 2a obtained by injection molding does not require very strict precision, but if the surface precision of the preform 2a is extremely poor, air is applied to the surface of the molded product during press molding. Care must be taken because accumulation occurs and it takes time to improve surface accuracy.

Further, as shown in FIGS. 2 and 3, the shape of the prism preform 2a is smaller than the product shape in a direction perpendicular to one surface of the prism so that a press allowance t at the time of press molding exists. It is desirable that the shape is slightly larger and slightly smaller than the shape of the product 2 in a direction parallel to the same plane. The volume of the preform 2a shown in FIG. 2 is desirably about the same as the volume of the product 2 shown in FIG. 1 (-3% to + 3%, preferably -1% to + 1%).

For example, when an optical prism having a triangular prism shape (base length w1 and height h0) as shown in FIG. 1 is to be obtained as the product 2, the prism preform 2a
Is a pentagonal prism shape (w0 × ho) as shown in FIG.
(Combined shape of a triangle of w0 × t and a rectangle of w0 × t). In addition, the press allowance t by press molding,
That is, as the dimensional difference in the pressing surface direction X between the prism preform 2a and the shape of the product 2, the preform 2a
Must be greater than the surface accuracy of
= 15 μm or more. Note that the pushing allowance t
If it is extremely large, for example, exceeding 5 mm, it is not preferable because a long time is required for press molding, burrs may be generated, and surface accuracy may be reduced. When the height of the product is h0, t / h0 is preferably 9.0 × 10 ^{−4 to} 3.0 ×.
10 ^-1 , more preferably 6.0 × 10 ^{-3 to} 6.0 × 1
0 ^-2 . The width w0 and the depth length of the preform 2a (the length of the preform 2a in the direction perpendicular to the paper surface) are the same as those of the preform 2a and the product 2 at the stage when the pressing allowance t is determined. Thus, the width is determined to be smaller than the width w1 and the depth of the product. For example, the ratio w0 / w1 of the width of the preform and the product is preferably 8.0 × 10
^{−1 to} 9.9 × 10 ⁻¹ , more preferably 9.5 × 10 ⁻¹
９9.0 × 10 ⁻¹ . Further, the ratio of the depth length of the preform and the product is the ratio w0 / w1 of the width of the preform and the product.
About the same.

In the present embodiment, press molding is performed by
This is performed by changing the heating temperature and the pressing pressure over time shown in FIG.

That is, the preformed preform 2a
Is press-molded using the molds 4 and 6 shown in FIG. 3, first, the preform 2a is pressurized with the initial pressure P0,
The temperature of the compact 2a is raised to T1. As a means for raising the temperature of the molded body to T1, an electric heater, an infrared lamp, or the like is used. In this embodiment, the heating rate is (6.0 × 10 ^{−2 to} 6.0 × 10 ⁻¹ ) ° C./sec. When the temperature of the molded body reaches its maximum temperature T1, the state is maintained for a certain time (soak time ST). The initial pressure remains at P0.

In FIG. 3, reference numerals 8 and 10 indicate mold mounting plates, reference numerals 12 and 14 indicate shafts, and reference numeral 20 indicates a hood. In the example of FIG. 3, the lower mold 6 is movable.

In the present embodiment, the maximum temperature T1 is the glass transition temperature (Tg) of the thermoplastic resin constituting the molded body 2a.
(Tg + 20) ° C. to (Tg + 90) ° C. The initial pressure P0 is 10 to 80 kgf / cm ²
It is. The soak time ST is a preheating time, which is 1 to 100 seconds in the present embodiment. After the elapse of the soak time ST, the molded body 2a is pressed, and the press time PT is 1 to 100 seconds in the present embodiment.

In this embodiment, the middle press pressure P1 at the press time PT is the same as the initial pressure P0, but may be set to a different pressure. When different pressures are set, the medium-term press pressure P1 of the press time PT is
It is preferable to set higher than the initial pressure P0.

After the end of the press time PT, the compact is cooled. Cooling is performed by supplying an inert gas such as nitrogen gas to the dies 4 and 6 shown in FIG. At the stage when the temperature of the compact has decreased to T2, the middle press pressure is increased from the initial cooling pressure P2 to the middle cooling pressure P3.
In this embodiment, the temperature T2 at the time of cooling, which is a reference for the switching, is (Tg + 5) ° C. to (Tg + 40) ° C. with respect to the glass transition temperature (Tg) of the thermoplastic resin, and (T1- 85) ° C to (T1-15) ° C.
In the present embodiment, the initial cooling pressure P2 is equal to the middle pressing pressure P1.
Is the same as above, but need not be the same, and may be set lower.

The medium-term cooling pressure P3 is P1 + 10 kgf / cm ^{2 to} P1 + 190 kgf with respect to the medium-term press pressure P1.
/ Cm ² . By setting the middle-stage cooling pressure P3 higher than the middle-stage press pressure P1, it is possible to reduce the accumulation of air formed on the surface of the compact.

The pressing pressure after the stage at which the temperature of the compact has been cooled to T3 is the final cooling pressure P4. In the present embodiment, the final cooling pressure P4 is the same as the middle cooling pressure P3.
The final cooling pressure P4 may be set lower than the middle cooling pressure P3. The temperature T3 is (Tg−10) ° C. to (Tg) with respect to the glass transition temperature (Tg) of the thermoplastic resin.
g + 10) ° C. and (T1-10) ° C.
(T1-100) ° C is determined.

At the stage when the temperature of the compact has been cooled to T4,
The molds 4 and 6 for press molding are opened, and the product 2 obtained by molding is taken out. The temperature T4 is not particularly limited as long as the molded body can be taken out.
It is about 20 ° C.

In this embodiment, the cooling time C under the action of the initial cooling pressure P2, the middle cooling pressure P3, and the final cooling pressure P4
In 1, C2 and C3, the compact is cooled at the same cooling rate. The cooling rate of this embodiment is (6.0 × 10 ^−2).
６6.0 × 10 ⁻¹ ) ° C./sec. The cooling rate may be different for each of the cooling times C1, C2, and C3. In that case, each cooling time C
The relationship among the cooling speeds V1, V2, and V3 corresponding to 1, C2, and C3 preferably satisfies the relationship of V3 ≧ V1 ≧ V2.

In the press molding, since the characteristics of the obtained product are considerably affected by differences in conditions such as a heating rate, a soak time (ST), a press time, and a cooling rate, these conditions are optimized. Is desired. That is, shortening the soak time and lowering the cooling rate are preferable from the viewpoint of reducing the birefringence of the product, and increasing the pressing force in the cooling process is preferable from the viewpoint of improving the surface accuracy. If the soak time is extremely short, for example, less than 1 second, it is not preferable because the surface accuracy may be reduced.

The specific conditions cannot be specified unconditionally because they depend on the kind of the thermoplastic resin to be used and the like.
It is preferable from the viewpoint of manufacturing an optical prism having good surface accuracy and low birefringence.

Characteristics of Optical Prism The optical prism according to the present embodiment has excellent characteristics in both birefringence and deformation due to environmental changes. Furthermore, by selecting the molding conditions, the surface accuracy is measured by an optical interferometer, the entire surface is 15 μm or less, preferably 10 μm or less. It will be greatly improved.

[0093]

EXAMPLES Hereinafter, the present invention will be described based on more detailed examples, but the present invention is not limited to these examples. In the following examples, parts and percentages are by weight unless otherwise specified.

The performance evaluation of the optical prism obtained in the following examples was performed as follows.

A polarizing plate having a phase difference of 90 ° is disposed before and after the birefringence evaluation optical prism, light (white light) is incident from one of the polarizing plates, and interference colors appearing on the prism are visually observed. Was used to evaluate the degree of birefringence. In addition, when the interference fringe pattern is large, the birefringence is large, and when the interference fringe pattern is small, the birefringence is small. The evaluation is ◎: no interference fringe pattern, ○: one, Δ: two, x: interference fringe pattern However, it was based on a four-stage evaluation of three or more.

Deformation due to environmental change In a thermoplastic resin lens, deformation due to humidity often becomes a problem among environmental conditions. Therefore, as a representative characteristic, the water absorption was measured in accordance with ASTM D570.

Evaluation of Surface Accuracy As shown in FIG. 5, each surface of the triangular prism was
The surface, the B surface, and the C surface were measured by scanning the diagonal line of each surface with an optical interferometer (manufactured by Taylor Hobson).

(Production Example 1 of Thermoplastic Resin) Under a nitrogen atmosphere, 6-ethyl-1,4: 5,8-dimethano-1,4,4
100 parts by weight of 4a, 5,6,7,8,8a-octahydronaphthalene (hereinafter abbreviated as ETCD) are polymerized with a known metathesis ring-opening polymerization catalyst system, and then hydrogenated by a known method to give an ETCD ring-opened polymer. A hydrogenated product was obtained. This ET
The hydrogenated product of the CD ring-opening polymer has a number average molecular weight M measured by GPC (gel permeation chromatography) using cyclohexane as a solvent in terms of polyisoprene.
n was 28,000. The hydrogenated DCP ring-opening polymer was dried by a known method. By the proton NMR method, the hydrogenation rate before and after the hydrogenation reaction was 99.
8% or more, Tg measured by DSC is 138 ° C., 2
The refractive index at 5 ° C was 1.53 (based on ASTM D542). 0.1 parts by weight of the pellets.
2 parts by weight of a phenolic antioxidant pentaerythrityl-tetrakis (3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate) and 0.4
Parts by weight of hydrogenated styrene / butadiene / styrene / block copolymer (ToughTech H105 manufactured by Asahi Kasei Corporation)
1, a crumb shape, a refractive index of 1.52 at 30 ° C.) were mixed and kneaded with a biaxial kneader, and a strand (rod-shaped molten resin) was passed through a strand cutter to obtain a pellet (granular) molding material. The pellet is heated for 20 m by a hot press (resin temperature 200 ° C., 300 kgf / cm ² , 3 minutes).
A plate having a size of mx 15 mm and a thickness of 3.0 mm was formed. The plate was transparent and had a minimum light transmittance of 90.0% between 400 and 700 nm. This plate was sliced to a thickness of about 0.05 μm, the polystyrene portion was stained with ruthenium tetroxide, and observed with a transmission electron microscope. As a result, the rubbery polymer was found to have a diameter of about 0.04 μm in a resin matrix. It had a spherical microdomain structure. The glass transition temperature of the pellet was 138 ° C.

(Production Example 2 of Thermoplastic Resin) Instead of ETCD, 8-methyl-1,4: 5,8-dimethano-1,
Instead of 30 parts by weight of 4,4a, 5,6,7,8,8a-octahydronaphthalene (hereinafter abbreviated as MTCD) and 70 parts by weight of dicyclopentadiene (hereinafter referred to as DCP) (total 1)
00 parts by weight), hydrogenated styrene / butadiene / styrene
A hydrogenated MTCD / DCP ring-opening copolymer was obtained in the same manner as in Production Example 1 except that the block copolymer was not used. When the copolymerization ratio of each norbornene in the polymer was calculated from the residual norbornene composition (by gas chromatography) in the solution after polymerization, MTCD / T
The CD = 30/70 was almost equal to the charge composition. This M
The hydrogenated TCD / DCP ring-opening polymer has Mn of 2
7,000, hydrogenation rate of 99.8% or more, Tg
Was 130 ° C.

(Production Example 3 of Thermoplastic Resin) In a stainless steel autoclave equipped with an electromagnetic stirrer having a content of 1 liter and thoroughly dried and purged with nitrogen, 320 parts of dehydrated cyclohexane, 80 parts of styrene monomer and dibutyl ether 1.83 parts were charged, and while stirring at 400 ° C. and 400 rpm, 0.31 part of an n-butyllithium solution (hexane solution containing 15%) was added to initiate polymerization. After polymerization for 3 hours under the same conditions, 0.42 parts of isopropyl alcohol was added to stop the reaction. When the weight average molecular weight (Mw) and the number average molecular weight (Mn) of the produced aromatic vinyl polymer a were measured, Mn = 113,6
36, Mw = 125,000.

Next, 400 parts of the polymerization solution containing the aromatic vinyl polymer a was added to the stabilized nickel hydrogenation catalyst N16.
3A (manufactured by Nippon Chemical Co., Ltd .; 40% nickel-supported silica)
Alumina carrier (12 parts) was added and mixed, and charged into a 1.2-liter stainless steel autoclave equipped with an electric heating device and an electromagnetic stirrer for adjusting the hydrogenation reaction temperature. After completion of the charging, the inside of the autoclave was replaced with nitrogen gas, and while stirring at a rotation speed of 700 rpm,
A hydrogenation reaction was performed at 230 ° C. and a hydrogen pressure of 45 kg / cm ² for 8 hours.

After the completion of the hydrogenation reaction, the hydrogenation catalyst was removed from the reaction solution by filtration, 1200 parts of cyclohexane was added, and the mixture was poured into 10 liters of isopropanol to precipitate a hydrogenated product A of an aromatic vinyl polymer. Was.

After the hydrogenated product A is separated by filtration, it is dried by a reduced-pressure drier and the aromatic vinyl polymer hydrogenated product A is dried.
Was recovered. The physical properties of the obtained hydrogenated product A were Mn = 4.
8,421, Mw = 92,000, Mw / Mn = 1.9
0, the degree of hydrogenation was 100%, and Tg was 140 ° C.

[0104] The pellets of Example 1 above Production Example 1, by clamping pressure 125 t injection molding machine, and injection molded at a resin temperature of 290 ° C, mold temperature of 60 ° C during molding, Fig. A preform 2a having the shape shown in FIG.

The width dimension W0 is 39.93 mm, the height h0 of the product is 20.0 mm, the pushing allowance t is 0.08 mm, and the depth dimension (perpendicular to the plane of the drawing) is 44.8 mm.
The volume was 18000 mm ³ . In addition, the weight of the molded body 2a was 18.286 g. Each surface A of the molded body,
When the surface accuracy was measured for B and C, A / B / C
Was 15 μm / 17 μm / 20 μm.

The molded body was set in the dies 4 and 6 shown in FIG. 3 and press-molded. FIG. 4 shows changes in temperature and press pressure during press molding.

Press pressure P0 = P1 = P3 = 500 kgf
/(39.93×44.8 mm ² ) = about 28.0 kgf
/ Cm ² , P3 = P4 = 1900 kgf / (39.93
× 44.8 mm ² ) = about 106 kgf / cm ² . The maximum temperature T1 = 170 ° C., T2 = 150 °
C, T3 = 130 ° C., T4 = 100 ° C. T
The heating rate up to 1 was (5.8 × 10 ^-1 ) ° C./sec, the soak time ST was 10 seconds, and the press time P
T is 10 seconds, and the cooling rates at the cooling times C1 and C2 and the cooling rate at the cooling time C3 are respectively (7.4
× 10 ^-2 ) ° C and (1.6 × 10 ^-1 ) ° C / sec.

The width W1 of the prism product 2 (see FIG. 1) obtained by press molding is 40.0 mm, the depth is 45 mm, and the height h0 is 20.
It was 0 mm. When the above-mentioned birefringence evaluation was performed using this prism product, it was ◎ and the water absorption was 0.01%.
It was below. When the surface accuracy was measured for each of the surfaces A, B, and C, A / B / C was 9 μm / 9 μm.
m / 9 μm. Further, when the surface of the prism product was observed, no air accumulation was observed.

Example 2 A prism product was obtained in the same manner as in Example 1 except that a preform (surface of the A side was 10 μm) obtained by injection molding using a mold having no pear finishing. .

When the above-mentioned evaluation of birefringence was performed using this prism product, the result was ◎, and the water absorption was 0.01% or less. Further, when the surface accuracy was measured for each of the surfaces A, B, and C, 9 μm / 9 μm /
It was 9 μm. Further, when the surface of the prism product was observed, no air accumulation was observed.

Example 3 The preformed body obtained by subjecting the preformed body obtained by injection molding to the A, B, and C planes to be subjected to an annealing treatment at 150 ° C. for 1800 seconds and then having the surface shape adjusted by milling is used as the preformed body. In the same manner as in Example 1, a prism product was obtained.

Using this prism product, the above-described evaluation of birefringence was evaluated as ◎, and the water absorption was 0.01% or less. Further, when the surface accuracy was measured for each of the surfaces A, B, and C, 9 μm / 9 μm /
It was 9 μm. Further, when the surface of the prism product was observed, no air accumulation was observed.

Comparative Example 1 The same procedure as in Example 1 was performed except that the prism product shown in FIG. 1 was directly molded by injection molding (no press molding step) instead of molding the preformed body shown in FIG. 2 by injection molding.
In the same manner as in the above, a prism product was obtained.

When the above-mentioned evaluation of birefringence was performed using this prism product, the result was x. In addition, each surface A, B, C
When the surface accuracy was measured, A / B / C was 11 μm / 17 μm / 21 μm.

Example 4 Pressing pressure P0 = P1 = P3 = about 8.0 kgf / cm ² ,
A prism product was obtained in the same manner as in Example 1 except that P3 = P4 = 0 kgf.

When the above-mentioned birefringence evaluation was performed using this prism product, the result was ○, and the water absorption was 0.01% or less. The surface accuracy was measured for each of the surfaces A, B, and C. As a result, A / B / C was 35 μm / 20 μm.
m / 25 μm.

Example 5 A prism product was obtained in the same manner as in Example 1 except that the maximum temperature T1 was set to 150 ° C. lower than (Tg + 20), and T2 was set to 145 ° C. and T3 was set to 130 ° C. Was.

Using this prism product, the above-mentioned evaluation of birefringence was performed. The result was Δ, and the water absorption was 0.01% or less. When the surface accuracy was measured for each of the surfaces A, B, and C, 58 μm / 47 μm was obtained for A / B / C.
m / 45 μm.

Example 6 A prism product was obtained in the same manner as in Example 1 except that the maximum temperature T1 was set to 240 ° C. higher than (Tg + 90), and T2 was set to 150 ° C. and T3 was set to 130 ° C. Was.

Using this prism product, the above-described evaluation of birefringence was evaluated as ◎, and the water absorption was 0.01% or less. When the surface accuracy was measured for each of the surfaces A, B, and C, A / B / C was 20 μm / 15 μm.
m / 19 μm.

Example 7 The procedure of Example 1 was repeated, except that the cooling rate during the cooling times C1, C2 and C3 was set to (2.3 × 10 ^-1 ) ° C./sec faster than in Example 1. A prism product was obtained.

Using this prism product, the above-mentioned evaluation of birefringence was performed. The result was Δ, and the water absorption was 0.01% or less. When the surface accuracy was measured for each of the surfaces A, B, and C, it was found that A / B / C was 16 μm / 9 μm.
/ 11 μm. Further, when the surface of the prism product was observed, no air accumulation was observed.

Example 8 The pellets of Production Example 2 were injection-molded using a 125-ton injection molding machine at a mold temperature of 280 ° C. and a mold temperature of 60 ° C. The prism product was obtained in the same manner as in Example 1 except that a preform having the shape shown in FIG.

Using this prism product, the above-mentioned evaluation of birefringence was evaluated as ◎, and the water absorption was 0.01% or less. Further, when the surface accuracy was measured for each of the surfaces A, B, and C, 9 μm / 9 μm /
It was 9 μm. Further, when the surface of the prism product was observed, no air accumulation was observed.

Example 9 A hydrogenated polymer A of the aromatic vinyl polymer produced in Production Example 3 was added to a rubbery polymer (Toughtec H105 manufactured by Asahi Kasei Corporation).
2, 0.2 parts of glass transition temperature of 0 ° C. or less), 0.05 of antioxidant (Irganox 1010 manufactured by Ciba-Geigy)
And a twin-screw kneader (TEM-35 manufactured by Toshiba Machine Co., Ltd.)
B, screw diameter 37 mm, L / D = 32, screw rotation speed 250 rpm, resin temperature 240 ° C., feed rate 10 kg / hour), extruding, pelletizing, and using the obtained pellets, Nissei Plastic Industrial Co., Ltd. Made of F
E210 injection molding machine, resin temperature at the time of molding 300 °
C. A prism product was obtained in the same manner as in Example 1 except that injection molding was performed under the conditions of a mold temperature of 120 ° C. to obtain a preformed body shown in FIG.

Using this prism product, the above-mentioned evaluation of birefringence was performed. The result was ◎, and the water absorption was 0.01% or less. Further, when the surface accuracy was measured for each of the surfaces A, B, and C, 9 μm / 9 μm /
It was 9 μm. Further, when the surface of the prism product was observed, no air accumulation was observed.

Comparative Example 2 Injection molding was performed directly in the same manner as in Comparative Example 1 except that a polymethyl methacrylate resin (Acrypet VH, manufactured by Mitsubishi Rayon Co., Ltd.) was used and the resin temperature was set to 250 ° C. Obtained.

The birefringence of this prism was ◎, and the water absorption was 0.3%.

As described above, according to the present invention, a plastic optical prism having excellent surface accuracy and birefringence is provided in a plastic optical prism having excellent weight, impact resistance, workability and the like. be able to.

[Brief description of the drawings]

FIG. 1 is a plan view showing a shape of an optical prism according to one embodiment of the present invention.

FIG. 2 is a plan view showing the shape of a prism preform used for manufacturing an optical prism according to one embodiment of the present invention.

FIG. 3 is a sectional view of a main part showing an example of a press molding die.

FIG. 4 is a graph showing a change in temperature and a change in press pressure in press molding.

FIG. 5 is a perspective view showing names and measurement directions of respective surfaces in the evaluation of the surface accuracy of the optical prism according to the embodiment of the present invention.

[Explanation of symbols]

 2 ... Prism product 2a ... Pre-formed body 4, 6 ... Mold

Continuation of the front page (72) Inventor Keiichi Kawata 1-2-1 Yoko, Kawasaki-ku, Kawasaki-shi, Kanagawa Prefecture, Japan Zeon Corporation General Development Center

Claims (4)

[Claims] 1. An optical prism obtained by preforming a thermoplastic resin having a saturated hydrocarbon ring to form a prism preform, and then press-molding the preform. 2. The optical prism according to claim 1, wherein the thermoplastic resin is a thermoplastic nobornene resin. 3. A preform that is slightly larger than the product shape in a direction perpendicular to one surface of the prism and slightly smaller than the product shape in a direction parallel to the same surface by injection molding a thermoplastic resin. A method for producing an optical prism by press-molding the preform. 4. The press molding according to claim 1, wherein the pressure is 10
200 kgf / cm ² , the maximum temperature is (Tg + 20) ° C. with respect to the glass transition temperature (Tg) of the thermoplastic resin.
The method for producing an optical prism according to claim 3, wherein the method is performed under a condition of (Tg + 90) ° C.