JPS5817924B2 - Manufacturing method of synthetic resin body for optical transmission - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing a synthetic resin body for optical transmission using a photocopolymerization reaction.

2. Description of the Related Art Optical transmission bodies made of glass or plastic have been known in the past, and are used, for example, in fields such as medical equipment, display devices, and optical display devices.

It is expected that its utility value will become extremely high in the field of information communication equipment in the future.

Among these optical transmitters, those capable of transmitting images have a structure with a refractive index distribution that increases continuously from the periphery toward the center, and the manufacturing method thereof is extremely difficult. A method for industrially manufacturing optical transmitters using synthetic resins with constant quality and high yield has not yet been established.

One method of producing synthetic resin bodies for optical transmission that has been developed so far is to continuously change the refractive index by diffusing and replacing different metal ions from the periphery to the center of an ionically crosslinked synthetic resin body. A synthetic resin body formed from a mixture of two or more transparent polymers with different refractive indexes is treated with a solvent of a specific composition, and the concentration of the specific component in the composition constituting the synthetic resin body is changed to that level. A method of selective extraction in which the refractive index changes continuously from the center to the periphery.A linear synthetic resin body is used as the base material, and monomers with different refractive indexes are diffused from the surface and polymerized. , a method of forming a refractive index distribution by giving a composition distribution that changes continuously from the periphery toward the center, or a method of forming a refractive index distribution by mixing two types of monomers with different refractive indexes and prepolymerizing them, Manufacturing methods are known, such as a method in which a polymer is selectively volatilized from the surface and then the polymerization is completed again to form a refractive index distribution.

However, these manufacturing methods involve immersing the molded synthetic resin body in a solvent or monomer solution again, or taking out the synthetic resin body that has not yet been sufficiently molded during polymerization step 4 and carrying out the next process. There was a problem in that the synthetic resin body was easily deformed due to the application.

Furthermore, the manufacturing process requires multiple steps, and the process of providing the refractive index distribution involves ion exchange, polymer extraction, monomer diffusion, or monomer volatilization, which is a method that is extremely difficult to control. This method also had the disadvantage that it was difficult to produce a synthetic resin body for optical transmission with stable quality.

As a new production method that eliminates these drawbacks, a production method has been reported in which a refractive index distribution is formed simultaneously with polymerization by utilizing the difference in the reactivity ratio of heptamers in a copolymerization reaction.

[Ohuma, Chino, Nakamoto, Proceedings of the Institute of Electrical Communication Engineers (Autumn 1975)] This method involves placing two or more types of monomers with different refractive indexes and monomer reactivity ratios in a copolymerization reaction in a transparent tubular glass container, and light. It is filled with a solution containing a polymerization initiation catalyst and irradiated with light from the tube wall to initiate polymerization from the tube wall, forming a composition distribution that continuously changes from the periphery to the center of the tubular synthetic resin body. Thereby, a synthetic resin body for light transmission having a refractive index distribution is manufactured.

To explain this method in more detail, when a monomer M1 with a large refractive index and a monomer M2 with a small refractive index are used as a combination of monomers for copolymerization, the monomers M1 and M2 are copolymerized. The monomer reactivity ratio in the polymerization reaction is required to be rl<1 and r2>■.

For example, the monomer reactivity ratio is r 1 ""0.4.
Composition of M2 in the monomer mixture when combining monomers with r2=2.0; f2=M2/(Ml 10M
2) Composition of M2 in the synthetic resin body polymerized with F2=
dM, /(dM1+dMρ (however, dM represents the amount of polymerized monomer).

) is shown in Figure 1. When equal amounts of monomers M1 and M2 are charged, the amount of monomer M1 in the polymerized synthetic resin is 3.
2 mole charge, M2 can talk about 68 mole charge.

As a result, the composition (f2) of M2 in the monomer mixture decreases as the polymerization progresses, and therefore the composition F2 of the polymerized synthetic resin body also decreases as the polymerization time progresses.

Next, let us consider the refractive index distribution of the synthetic resin body photocopolymerized in a transparent tubular glass container, assuming that the refractive index of the Ml polymer is 1.5 and the refractive index of the M2 polymer is 1.4. Shown in Figure 2.

In the figure, 1, 2, 3 and 4 indicate the monomer charging composition; f2 is 0.8, 0.5, 0.3 and 0.1, respectively.

As can be understood from Fig. 2, the peripheral part of the tubular synthetic resin body polymerizes in the early stage and has a high ratio of M2 polymer and a low refractive index, but the central part, which polymerizes in the later stage, has a higher proportion of M1 polymer. is high and the refractive index is also high.

It can be seen that this refractive index distribution changes depending on the monomer composition.

The refractive index distribution also depends on the type of photopolymerization initiation catalyst and its concentration, and the higher the concentration, the larger the refractive index distribution of culm waste, and the better the performance as a synthetic resin body for light transmission.

The refractive index distribution of the synthetic resin body for light transmission is expressed by equation (1).

N here.

is the refractive index of the central axis, A is the refractive index distribution constant, r is the distance from the central axis, and N represents the refractive index at the position of r.

In order to increase the refractive index distribution constant A, it is necessary to decrease the monomer charge composition f2 and increase the photopolymerization initiator concentration.

In this way, by utilizing the difference in refractive index and the reactivity ratio of monomers in the copolymerization reaction, the monomer mixture in the tubular glass container is irradiated with light from the tube wall, and photocopolymerization is carried out so that the polymerization starts from the tube wall. The synthetic resin body for light transmission obtained by this method has the drawback that the molecular weight of the polymer is small as a result of increasing the concentration of the photopolymerization initiation catalyst in order to increase the refractive index distribution constant, and it is extremely brittle.

Due to this disadvantage of brittleness, it is difficult to produce a complete product without defects, and as is, it cannot be satisfactorily used as an industrial manufacturing method.

The present inventors have conducted extensive research with the aim of eliminating these conventional drawbacks and obtaining even better synthetic resin bodies for optical transmission. As a result, we have found that at least A mixture of two types of monomers with a photopolymerization initiation catalyst and a plasticizer capable of initiating photopolymerization is filled into a light-transmitting tube, and the mixture is irradiated with light to perform photocopolymerization from the tube wall. The present inventors have discovered that it is possible to obtain a synthetic resin body for light transmission that has excellent mechanical strength and a large refractive index distribution constant, and has completed the present invention.

A plasticizer that has the ability to initiate photopolymerization is a plasticizer that is uniformly dissolved in monomers, has the ability to polymerize the monomers by light irradiation, and lowers the glass transition temperature of the polymer obtained as a result of polymerization of the monomers. A substance that has abilities.

The use of plasticizers can be considered as a way to improve the brittleness that is a drawback of synthetic resin bodies for optical transmission manufactured by photocopolymerization, but in our experiments, we used commercially available phthalate esters as plasticizers. When used, an improvement in mechanical strength was observed, but it was also found to be accompanied by a significant decrease in the refractive index distribution constant.

As a result of a detailed study of this fact, it became clear that the refractive index distribution constant decreased because the added plasticizer inhibited the catalytic action of the photopolymerization initiation catalyst.

Therefore, we believe that the decrease in the refractive index distribution constant can be prevented by using a plasticizer that does not inhibit the catalytic action of the photopolymerization initiation catalyst, or a plasticizer that has the ability to further initiate photopolymerization, and we are searching for such a plasticizer. As a result, it was found that esterification of the carbonyl group of tocopherol or its derivatives having phytol in the side chain, or esterification of the hydroxyl group of quinone or its derivatives having phytol in the side chain, is effective. It is.

Therefore, in this invention, a photopolymerization initiation catalyst and a plasticizer having photopolymerization initiation ability are added to two or more types of monomers having different refractive indexes and 7-mer reactivity ratios in a copolymerization reaction in a light-transmitting tube. The present invention is characterized in that a synthetic resin body for light transmission having excellent mechanical strength and a large refractive index distribution constant can be easily obtained by filling the mixture and performing photocopolymerization from the tube wall.

Examples of the above monomers include methyl methacrylate, styrene, vinylnaphthalene, vinylbenzoic acid, methyl cinnamate, ethyl cinnamate, 4-vinylpyridine,
Examples include cinnamate nitrile and acrolein, and a combination of at least two types of monomers selected from these is used.

Examples of the photopolymerization initiation catalyst include benzophenone,
Examples include benzoin, benzoin methyl ether, etc.
At least one of these is used.

In addition, the amount of the polymerization initiation catalyst added is 1 to 20% by weight,
Particularly preferred is a weight ratio of 5 to 10).

Examples of the plasticizer having photopolymerization initiating ability include EVA α-
Tocopherol acetic acid, d-α-tocopherol succinate, tocopheramine, α-tocopherothiol, α-tocopherothioacetic acid, α-tocopherodisulfide dimer,
α-tocopheroselenoacetic acid, di-α-tocopherodyselene compound, α-tocophenylquinone diacetate, β-
Tocophenylquinone ciacade, γ-tocophenylquinone diacetate, plastoquinone C diacetate, plastoquinone C diacetate, plastoquinone C diacetate plastoquinone D diacetate ubiquinone-n-
Diacetate, rhodoquinone-n-diacetate Dimethoxyubiquinone-n-diacetate Dimethylubiquinone-n-diacetate Dihydroubiquinone-10-diacetate Epoxyubiquinone-n-diacetate, Nibuchromeno-n-diacetate, Phylloquinone (vitamin 2 ) Cyanade (i.e. 2-methyl-3-phytyl-1,4-naphthoquinone diacetate), Menaquinone diacetate (vitamin 2) (i.e. 3-methyl-2-phytyl-1,4-naphthoquinone diacetate)
etc., and at least one of these is used.

In addition, the amount added is 5 to 20% by weight, especially 10 to 1% by weight.
5 weight ratio is preferable.

If the amount added is less than 5% by weight, the improvement effect will be insufficient, and if it is more than 200% by weight, there will be a problem that the polymer will become brittle, so either case is not preferred.

The mixture of the above components is filled into a transparent tube such as a glass tube, and is polymerized by irradiation with light using known conventional techniques, which simplifies the process and improves mechanical strength. A synthetic resin body can be easily obtained.

Note that there is no problem in completing the polymerization by heating as necessary.

The synthetic resin body thus obtained is useful as an optical information transmission medium, such as a launcher used as a coupling part between an optical semiconductor element and an optical fiber.

Hereinafter, the present invention will be explained in more detail with reference to Reference Examples and Examples of the present invention.

Example 1 Inner diameter 3. In a thin Pyrex (trade name) glass tube with one end of Omrrt closed, 1 part methyl cinnamate to 4 parts methyl methacrylate containing 100% by weight benzoin methyl ether and 100% by weight α-tocopherol acetate was added. The other end of the glass tube was sealed.

(The refractive index of the cinnamate methyl ester is 1.58.
The refractive index of methacrylic acid methyl ester is 1.49.

Moreover, the monomer reactivity ratio is rl = Q, 16, r 2 =
It is 6.4.

) This product was solidified by irradiating it with light from a gysenon lamp for 10 hours in constant temperature water at 25°G.

The synthetic resin body thus obtained has a refractive index distribution that decreases continuously from the center toward the periphery as shown in Figure 3, and has no shape distortion and is a synthetic resin body for light transmission. It was excellent.

Example 2 Measurements were made on synthetic resin bodies for optical transmission obtained in the same manner as in Example 1, except that the blended amounts of α-tocopherol acetate (α-TA) were changed to 0, 3, 5.10, and 15% by weight, respectively. Table 1 shows the refractive index distribution constant and mechanical strength.

However, the symbols used in Table 1 above each represent the following items (the same applies hereinafter).As seen from Table 1 above, products that do not contain α-tocopherol acetate (α-TA) have a low Although it is not useful as an actual product, those containing α-tocopherol acetate have excellent mechanical strength and the refractive index distribution constant is reduced by only about 20%.

Reference Example 14 General di-n-octyl phthalate (DnOP) was used as a plasticizer instead of α-tocopherol acetate, and the blending amount was varied to 0, 3°5, and 10% by weight, respectively. Example 2 Table 2 shows the refractive index distribution constant and mechanical strength measured for the synthetic resin body obtained in the same manner as above.

As can be seen from Table 2 above, the mechanical strength of those containing di-n-octyl phthalate 15 (DnOP), which is commonly used as a plasticizer, increases with the amount added, but the refractive index distribution constant also decreases accordingly. However, when 10% by weight is added, there is a problem that the refractive index distribution constant decreases by about 70%.

Therefore, in general plasticizers, the amount must be kept at 3 to 5% by weight, which is not as significant as the 2θ decrease in the refractive index distribution constant, and no significant improvement in mechanical strength can be expected.

Reference Example 2 Under almost the same conditions as Example 1, without adding a plasticizer, the amount of benzoin methyl ether (BME) was 250 to 15
Table 3 shows the mechanical strength and refractive index distribution constant measured for the synthetic resin body obtained by changing the weight cap.

As shown in Table 3 above, benzoin methyl ether (B
When the blending amount of ME) is small, especially when the weight is less than 5, there is almost no lens effect.

However, when the amount added exceeds 10% by weight, the refractive index distribution constant suddenly increases.

Therefore, if a large refractive index distribution constant and a large mechanical strength are to be obtained, there is no other method than the present invention.

Example 3 Example 1 except that the blending ratio of methacrylic acid methyl ester (MMA) and cinnamic acid methyl ester (MCI) was changed.
Table 4 shows the refractive index distribution constant and mechanical strength measured for the synthetic resin body obtained in the same manner.

For comparison, α-tocopherol acetate (α
-TA) is also shown in the same manner.

As shown in Table 4 above, when α-tocopherol acetate (α-TA) is used, cinnamate methyl ester (
As the ratio of MCI) increases, the value of the refractive index distribution constant increases, but the mechanical strength slightly decreases.

On the other hand, in the case where α-tocopherol acetate (α-TA) is not added, it is almost useless at all ratios.

Example 4 Table 5 shows the refractive index distribution constants measured for a synthetic resin body obtained under the same conditions as Example 1 except that the combination of monomers was changed.

Example 5 A portion of vinyl benzoate containing 8 weight parts of benzophenone, 5 weight parts of vitamins, and 1 diacetate was placed in a thin glass tube made of Pyrex (trade name) with an inner diameter of 3.5 mm and closed at one end. Then, a mixed solution of 3 parts of MMA was filled, and the other end of the glass tube was closed.

(The refractive index of vinyl benzoate is 1.57, MM
The refractive index of A is 1.49.

In addition, the monomer reactivity ratio is r 1 = 0.048, r, 2 =
It is 8.3.

) This material was irradiated with xenon lamp light for 10 hours in constant temperature water at 30°C to solidify it.

The synthetic resin body thus obtained has A=1.2
10 mm, and had sufficient mechanical strength.

Example 6 A commercially available Teflon (trade name) tube with an inner diameter of 2.0 mm was filled with a mixed solution containing 8 parts of MMA, 2 parts of cinnamate methyl ester, 1 part of benzoin ethyl ether, and 1.5 parts of α-TA, and heated with a 500 W mercury lamp. After 2 hours of light irradiation, 80
The reaction was completed after 24 hours of polymerization in the open air at ℃.

The refractive index distribution coefficient of this material is 1.8×10-2m7rt
-2.

Example 7 The synthetic resin tube for image transmission obtained in Example 6 was stretched in a furnace at 80° C. to obtain a synthetic resin body for image transmission having a diameter of 350 μm.

The synthetic resin body for image transmission obtained by this method was capable of transmitting images of sufficient quality over a distance of several meters.

In addition, since the Tg is around room temperature and the fiber has excellent flexibility, it does not require reinforcement for mechanical strength like other optical fibers.

According to the invention described in detail above, a high-quality and stable synthetic resin body for light transmission can be obtained in which the refractive index decreases from the center toward the periphery through a simple process.

[Brief explanation of drawings]

Figure 1 shows the monomer composition f2 and the polymerized resin composition F2.
FIG. 2 is an explanatory diagram showing the change in refractive index from the center of a synthetic resin body copolymerized in a light-transmitting tube to the periphery of the tube wall. FIG. 3 is a characteristic diagram showing the refractive index distribution of a synthetic resin body for optical transmission obtained according to an embodiment of the present invention. In Figure 1, 12 is the composition of monomer M2 in a mixed solution of monomers M1 and M2 having different refractive indexes and monomer reactivity ratios in the copolymerization reaction, and F2 is the synthetic resin when the above mixed solution is polymerized. The composition of M2 in the body is shown. In addition, for 1 to 4 in Fig. 2, the above f2 is 0.8°0, respectively.
．． The cases of 5, 0.8 and 0.1 are shown.

Claims (1)

[Claims] 1. A mixture containing at least two types of monomers having different refractive indexes and monomer reactivity ratios in a copolymerization reaction, a photopolymerization initiation catalyst, and a plasticizer capable of photopolymerization initiation. A method for producing a synthetic resin body for light transmission, comprising the steps of filling a light tube with light, and irradiating the mixture with light to polymerize it. 2 The above photopolymerization initiation catalyst is added in an amount of 1 to 20% based on the total amount of single substances.
A method for producing a synthetic resin body for optical transmission according to claim 1, wherein the weight ratio is as follows. 3. The method for producing a synthetic resin body for optical transmission according to claim 1 or 2, wherein the plasticizer is added at a weight ratio of 5 to 20 relative to the total amount of monomers. 4. A method for producing a synthetic resin body for phototransmission according to any one of claims 1 to 3, in which an esterified hydroxyl group of tocopherols having phytol in the side chain is used as a plasticizer. . 5. Claim 1, in which a quinone having phytol in its side chain is reduced to a hydroxyl group by reducing the carbonyl group to form a hydroxyl group and further esterifying the hydroxyl group as a plasticizer.
A method for producing a synthetic resin body for optical transmission according to any one of Items 1 to 3.