JPH0486603A - Production of distributed refractive index optical transmission body - Google Patents

Abstract

PURPOSE:To obtain the optical transmission body which substantially prevents the phase sepn. of a polymer and has excellent transparency by using a mixture composed of the specific polymer and a monomer having the refractive index different from the refractive index of this polymer. CONSTITUTION:The polymer to be used is so formed that the polymer has radical polymerizable functional groups in its side chains and that these groups exist in the quantity of >= 0.2 mol% per repeating unit of the polymer. The polymer having at least one kind of the radical polymerizable functional groups in the side chains and the monomer having the refractive index different from the refractive index of the polymer when polymerized or a monomer mixture composed of >= 2 kinds of the monomers including this monomer are mixed and after the mixture is molded to a fiber shape, the monomers are volatilized from the molding surface or the monomers are polymerized while volatilized. The distributed index type optical transmission body having the excellent transparency and the excellent surface hardness and heat resistance is obtd. in this way.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a method of manufacturing a gradient index optical transmission body having a continuous refractive index distribution from the surface toward the inside.

[Prior Art] As is well known, a gradient index optical transmission body consists of a transparent body with a distribution in which the refractive index gradually changes from the center to the periphery in a direction perpendicular to the optical axis, and includes rod-shaped lenses, Widely used as optical transmission fiber, etc.

The above optical transmission body has a refractive index on the central axis of n. , A is a constant, and the refractive index n at a distance r from the central axis has a distribution expressed by the following equation: 11=7'1o(1-%Ar2). Here, when the constant A is positive, the transmitter has a convex lens effect, and when A is negative, it has a concave lens effect.

Such a refractive index distribution optical transmitter having a continuous refractive index distribution from the inside to the surface has already been developed in Japanese Patent Publication No. 1973-
A glass material has been proposed in Japanese Patent No. 816, etc., and is widely used for rod-shaped lenses, optical transmission fibers, and the like. However, the above-mentioned glass optical transmission body is produced in a batch manner and requires a long time, resulting in low productivity and high cost. Furthermore, since it is made of glass, it has a drawback of poor flexibility.

Several methods have been proposed for manufacturing optical transmission bodies made of plastic in order to solve the above-mentioned drawbacks.

For example, Japanese Patent Publication No. 47-26913 discloses a synthetic resin body made of an ionically crosslinked polymer that is ion-exchanged to continuously change the metal ion concentration from the central axis of the resin body toward the surface. Publication No. 47-28059 describes a product in which two or more types of transparent polymers with different refractive indexes are mixed and molded, and then extracted with a specific solvent to form a concentration distribution from the central axis of the resin body toward the surface. , Japanese Patent Publication No. 54-30301 and Japanese Patent Publication No. 58-1792
Japanese Patent Publication No. 5857/1987 describes a product that uses two types of monomers with different refractive indexes and creates a continuous refractive index distribution from the surface to the inside by devising a polymerization method.
No. 5,637,521 discloses a method in which monomers having different refractive indexes are impregnated from the surface of an incompletely polymerized crosslinked polymer so as to have a continuous concentration distribution, and then copolymerized. Japanese Publication No. 57-29682 discloses a method in which a continuous refractive index distribution is formed by diffusing and reacting low molecular weight compounds with different refractive indexes from the surface of a reactive polymer.

However, these conventional methods require a diffusion or extraction process to form the refractive index distribution, so the process takes a long time, productivity is extremely low, and there are many problems with industrialization. It had

In order to solve these problems, Japanese Patent Application Publication No. 6220940
No. 2 discloses that by mixing a thermoplastic polymer and a monomer, molding the mixture, and then volatilizing the monomer from the surface,
A method is disclosed in which a concentration distribution is created from the surface to the inside of a molded body and polymerization is carried out.

[Problem to be solved by the invention] However, in Japanese Patent Application Laid-Open No. 62-209402,
Because chemical bonds such as copolymerization do not occur between polymers or between polymers and monomers, phase separation tends to occur when monomers are polymerized (refractive index distribution light with good transparency). It was extremely difficult to obtain a transmitter.Also, due to its poor surface hardness and heat resistance, it was difficult to use it for applications that require heat resistance and dimensional stability, such as copier lenses, and other applications. In use, there has been a problem in that the lens surface is easily damaged.

The purpose of the present invention is to solve the above-mentioned conventional problems, and to make it possible to manufacture a gradient index optical transmitter that has excellent transparency, surface hardness, and heat resistance. be.

[Means to solve the problem] The present invention has the following configuration.

"At least one polymer (A) which has a radically polymerizable functional group in its side chain and is present in an amount of 0.2 mol % or more per repeating unit of the polymer, and when polymerized, the polymer ( A) is mixed with a monomer (B) having a different refractive index or a mixture of two or more monomers containing the monomer (B),
After shaping this into a fibrous form, the monomer (
A method for producing a gradient index optical transmitter, which comprises volatilizing or polymerizing B) while volatilizing it. ” Hereinafter, the present invention will be explained in detail.

In the method according to the present invention, first, a polymer (A) having at least one radically polymerizable functional group in its side chain, and a monomer having a refractive index different from that of the polymer (A) when polymerized. (
B) or a mixture of two or more monomers containing monomer (B) to form a solution.

The polymer (A) that can be used in the present invention may be a polymer obtained by any reaction method such as radical polymerization reaction, ionic polymerization reaction, polycondensation reaction, or polyaddition reaction. However, the side chain of this polymer must have a radically polymerizable functional group.

The radically polymerizable functional group mentioned here is not particularly limited as long as it undergoes a radical reaction (preferable examples include vinyl group, acrylic group, methacrylic group, allyl group, etc.). Methods for introducing the polymer into the side chains of polymers include copolymerizing monomers that have radically polymerizable functional groups in advance, and grafting compounds that have radically polymerizable functional groups onto the polymer after obtaining it. However, in this case, the polymer (
The amount of radically polymerizable functional groups present in the side chain of A) is 0.2 per repeating unit of the polymer, that is, per monomer unit.
It is necessary that the amount is mol% or more. If the amount is less than 0.2 mol%, the effects of the present invention will not be sufficiently exhibited.

In the present invention, the monomers used as the monomer mixture containing monomer (B) include methyl methacrylate,
Ethyl methacrylate, propyl methacrylate, butyl methacrylate, isobutyl methacrylate, 2-ethylhexyl methacrylate, lauryl methacrylate, dodecyl methacrylate, stearyl methacrylate, cyclohexyl methacrylate, dimethylaminoethyl methacrylate, diethylaminoethyl methacrylate, 2-hydroxyethyl methacrylate, glycidyl methacrylate , methacrylic acid, methyl acrylate,
Ethyl acrylate, allyl methacrylate, benzyl methacrylate, α-0-chlorophenylethyl methacrylate, penduhydryl methacrylate, 0-chloropenduhydrol methacrylate, p-cyclohexylphenyl methacrylate, α-p-diphenylethyl methacrylate, menthyl methacrylate , m-nitrobenzoyl methacrylate, 2-nitro-2-methyl-propyl methacrylate, α-phenyl-allyl methacrylate, α-phenyl-n-amyl methacrylate, α-
Phenylethyl methacrylate, β-phenylethyl methacrylate, tetrahydrofurfuryl methacrylate, vinyl methacrylate, phenyl cellosolve methacrylate, p-methoxybenzoyl methacrylate, ethylene chlorohydrin methacrylate, pentachlorophenyl methacrylate, phenyl methacrylate, eugenoyl methacrylate, m- Cresyl methacrylate, diacetylene methacrylate, ethylene glycol benzoate methacrylate, ethyl glycolate methacrylate, bornyl methacrylate, triethyl carbinyl methacrylate, butyl mercaptyl methacrylate, 0-chlorobenzyl methacrylate, tert-butyl methacrylate, α-methallyl methacrylate, β
-Methyl methacrylate, α-naphthyl methacrylate, cinnamyl methacrylate, o-cresyl methacrylate, furfuryl methacrylate, β-aminoethyl methacrylate, methyl-α-bromoacrylate, lead methacrylate, 2-chlorocyclohexyl methacrylate, 1-phenyl Cyclohexyl methacrylate, triethoxysilicol methacrylate, p-promophenyl methacrylate, 2,3-dibromopropyl methacrylate, 1-methylcyclohexyl methacrylate, n-hexyl methacrylate, β-bromoethyl methacrylate, methyl-α-chloroacrylate , β-naphthyl methacrylate, N-n-butyl methacrylamide, methacrylmethyl salicylate, ethylene glycol monomethacrylate, N-benzyl methacrylamide, β-phenylsulfone ethyl methacrylate, N-
Methyl methacrylamide, N-allyl methacrylamide, methacryl phenyl salicylate, N-α-methoxyethyl methacrylamide, N-β-methoxyethyl methacrylamide, cyclohexyl-α-ethoxy acrylate, 1゜3-dichloropropyl-2- Methacrylate, 2-methylcyclohexyl methacrylate, 3-methylcyclohexyl methacrylate, 4-methylcyclohexyl methacrylate, trimethyl-3゜3.5-cyclohexyl methacrylate, fluorenyl methacrylate, α-naphthyl carbinyl methacrylate, ethylene glycol dimethacrylate, diethylene glycol dimethacrylate, triethylene glycol dimethacrylate, polyethylene glycol non-200 dimethacrylate, hexamethylene glycol dimethacrylate, decamethylene glycol dimethacrylate, ethyl sulfide dimethacrylate, 1,4-cyclohexanediol dimethacrylate, Ethylidene dimethacrylate, pentaerythritol tetramethacrylate, 1. 1.
Methacrylates such as 3-trihydroperfluoropropyl methacrylate, 1.1.54-lihydroberfluoropentyl methacrylate, trifluoroethyl methacrylate, 2-hydroxyethyl methacrylate,
Styrene, 0-chlorostyrene, vinylnaphthalene, 0
-Methyl-p-methoxystyrene, 0-methoxystyrene, 0-methylstyrene, p-isopropylstyrene,
Styrenes such as p-methoxystyrene, 2°6-dichlorostyrene, and divinylbenzene, and allyls such as diallyl phthalate, isodiallyl phthalate, allyl acetate, and diethylene glycol bisallyl carbonate are preferably used.

The above monomers may be selected depending on the refractive index. At this time, as the monomer (B), for convenience of the subsequent process,
It is preferable to use a material that is as easily volatile as possible. Further, it is preferable to select a monomer so as to be a good solvent for the polymer, since this makes it easier to obtain a gradient index optical transmission body with excellent transparency.

Next, this mixed solution is formed into a fibrous form, which can be realized, for example, by using an apparatus as shown in FIG. That is, in FIG. 1, a fiber 5 is obtained by filling a cylinder 1 with the above mixed solution, extruding it with a piston 2, and discharging it from a nozzle 4.

In FIG. 1, 6 indicates a volatilization section, 7 indicates a light irradiation section, and 8 indicates a gas inlet.

Next, the monomer (B) is removed from the surface of the molded product having the monomer.
volatilizes and gives a continuous distribution of components in the mixture. That is, in the center part of the mixture, the component ratio is close to the charging ratio, but in the surface part, the ratio of monomer (B) is low. At this time, although the purpose can be achieved by simply leaving the molded body in the atmosphere, it is preferable from the viewpoint of productivity to leave it under reduced pressure or the like to forcibly volatilize it.

Finally, all unpolymerized monomers are polymerized to fix the concentration distribution thus obtained.

This polymerization is accomplished by applying external energy such as heat or actinic light. The atmosphere may be air, but it is preferable to carry out the reaction under an inert atmosphere such as nitrogen or argon in order to inhibit polymerization due to the influence of oxygen or prevent coloring due to oxidation.

In addition, as a polymerization initiator, diacyl peroxides such as benzoyl peroxide and lauroyl peroxide, ketone peroxides, peroxyketals, hydroperoxides, dialkyl peroxides, peroxydicarbonates, peroxy Common radical initiators such as esters and conventionally known photopolymerization initiators can be used. In addition to these polymerization initiators, it is an effective means to use accelerators and sensitizers in combination.

Furthermore, as a polymerization regulator, mercaptans such as t-dodecyl mercaptan and n-dodecyl mercaptan;
Chain transfer agents such as carbon tetrachloride can be used.

The gradient index optical transmission body of the present invention is used in a wide range of applications such as optical fiber optical coupling elements, lens arrays for copying machines, lens arrays for facsimile machines, lenses for printers, and contact lenses.

[Example] The present invention will be explained in more detail below with reference to Examples. In addition, the physical properties in Examples were measured as follows.

A. State of refractive index distribution After cutting the rod with the refractive index distribution into 1 mm thick pieces and polishing both sides, the refractive index distribution was determined by differential interferometry using an interference microscope (Interfaco, manufactured by Carl Zeiss). was measured, and the refractive index difference Δn between the peripheral part and the central part was determined.

B0 Surface Hardness The hardness of the surface portion of the molded body was determined by pencil hardness according to JIS K5401.

After cutting the molded product with a C6 heat-resistant refractive index distribution into 3 mm thick pieces and polishing both sides, the central part was measured using a Vicat softening point measuring device (manufactured by Tsukiyama Kagaku Kikai Seisakusho Co., Ltd.) in accordance with JIS K7206. The softening point (1 kgf) was measured.

Example 1 90 parts by weight of methyl methacrylate, 10 parts by weight of methacrylic acid, 6 parts by weight of 2% polyvinyl alcohol aqueous solution and 2 parts by weight of benzoyl peroxide were added to 200 parts by weight of water, and suspension polymerization was carried out at 70°C for 6 hours under a nitrogen atmosphere. I let it happen. Next, the obtained polymer was dissolved in toluene, and β-methylglycidyl methacrylate was added dropwise at 50° C. for grafting. When this polymer was collected and its NMR spectrum was measured, the amount of grafting was found to be 11.4 mol%.

50 parts by weight of the polymer thus obtained, 50 parts by weight of benzyl methacrylate, 0.1 part by weight of 1-hydroxycyclohexylphenyl ketone and 0.1 part by weight of hydroquinone were charged into cylinder 1 of the apparatus shown in FIG.
It was heated to 80°C and extruded from a nozzle 4 having a diameter of 2.0 mm. Next, the extruded fiber is heated with nitrogen gas or
It passes through the volatilization section 6 flowing at a rate of 101/min at 0°C in 15 minutes, and is heated at 0°5 by the light irradiation section 7 consisting of an ultra-high pressure mercury lamp.
It was irradiated with light for a minute. A transparent fiber with a diameter of 1.1 Qmm was obtained. Using an interference microscope, it was confirmed that the refractive index changed continuously from the center to the periphery, and the refractive index difference Δn was 0.018. Moreover, the surface hardness was very hard, 4H, and the Vicat softening point was 133°C.

Comparative Example 1 100 parts by weight of methyl methacrylate in 200 parts by weight of water,
Add 6 parts by weight of 2% polyvinyl alcohol aqueous solution and 2 parts by weight of benzoyl peroxide, and heat at 70°C under nitrogen atmosphere for 6 hours.
Suspension polymerization was carried out for a period of time. 50 parts by weight of the polymer thus obtained, 50 parts by weight of benzyl methacrylate, 1-
Hydroxycyclohexylphenylketone 0. 1 part by weight and 0.1 part by weight of hydroquinone were charged into cylinder 1 of the apparatus shown in FIG. 1, and the same operation as in Example 1 was carried out to obtain a fiber having a diameter of 1.05 mm. The fiber was cloudy and the refractive index distribution could not be measured. Also,
The surface hardness was IH and the Vicat softening point was 99°C. It can be seen that both surface hardness and heat resistance are inferior compared to Example 1 of the present invention.

Example 2.3, Comparative Example 2 A graft polymer was obtained in exactly the same manner as in Example 1, except that the amounts of methyl methacrylate and methacrylic acid added during suspension polymerization were changed. The amount of graft in these graft polymers was as shown in Table 1. Next, fibers were obtained using these graft polymers in exactly the same manner as in Example 1. The fiber diameter, refractive index difference, surface hardness, and Vicat softening point were as shown in Table 1. From Table 1, the amount of grafting is 0.
It is less than 2 mol%.

It is clear that Comparative Example 2 has lower surface hardness and Vicat softening point than Example 2.3 of the present invention.

Example 4 80 parts by weight of methyl methacrylate, 20 parts by weight of glycidyl methacrylate, 6 parts by weight of 2% polyvinyl alcohol aqueous solution and 2 parts by weight of benzoyl peroxide were added to 200 parts by weight of water, and suspension polymerization was carried out at 70°C for 16 hours under a nitrogen atmosphere. Ta. Next, the obtained polymer was dissolved in toluene,
Grafting was carried out by dropping methacrylic acid at 50°C. When this polymer was recovered and its NMR spectrum was measured, the amount of grafting was 15.0 mol%. 50 parts by weight of the polymer thus obtained, 50 parts by weight of styrene,
0.1 part by weight of 1-hydroxycyclohexylphenyl ketone and 0.1 part by weight of hydroquinone were charged into cylinder 1 of the apparatus shown in FIG.
It was extruded from Omm nozzle 4. Subsequently, the extruded fiber was passed through a volatilization section 6 in which nitrogen gas flows at a rate of IOA'/min at 75° C. for 12 minutes, and was irradiated with light for 0.5 minutes using a light irradiation section 7 consisting of an ultra-high pressure mercury lamp. Diameter 1゜05
A transparent fiber of mm was obtained. Using an interference microscope, it was confirmed that the refractive index changed continuously from the center to the periphery, and the refractive index difference Δn was 0.020.
Met. In addition, the surface hardness is 3H, and the Vicat softening point is 1.
The temperature was 35°C.

[Effects of the Invention] The method for manufacturing a gradient index optical transmission body of the present invention has the following effects.

(1) It is possible to obtain a refractive index distribution optical transmission material in which the polymer is difficult to phase separate and has excellent transparency.

(2) A refractive index distribution can be formed in a short time, and continuous production is possible.

(3) A refractive index distribution optical transmitter with high polymer surface hardness and excellent heat resistance can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram showing an example of an apparatus for carrying out the method of manufacturing a gradient index optical transmission body of the present invention. 1 cylinder - 2: piston, 3: heater 4: nozzle,
5: Fiber 6: Volatile part, 7: Light irradiation part, 8: Gas inlet

Claims (1)

[Claims] (1) At least one polymer (A) having a radically polymerizable functional group in its side chain and present in an amount of 0.2 mol % or more per repeating unit of the polymer; Coalescence (A) refers to mixing a monomer (B) with a different refractive index or a mixture of two or more monomers containing the monomer (B), shaping it into a fiber, and then forming the mixture. 1. A method for producing a gradient index optical transmitter, which comprises polymerizing the monomer (B) while volatilizing or volatilizing the monomer (B) from the surface of the body.