JP2001290033A - Method for manufacturing plastic optical transmission material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for manufacturing a plastic optical transmission material which is capable of sufficiently degrading the transmission loss in a plastic optical fiber, etc. SOLUTION: In the method for manufacturing the plastic optical transmission material obtained by copolymerizing two kinds of monomers having reactivity ratios r1 and r2 satisfying the following equation r1×r2<0.8 or r1×r2>1.2 and having r1 smaller than 1 and r2 greater than 1, the monomer having the lower reactivity ratio is added to the material at >=20 to <100 pts.wt. when the reactivity ratios r1 and r2 satisfy r1/r2>=10 and at 100 to 500 pts.wt. when the reactivity ratios satisfy r/r2<10 per 100 pts.wt. monomer having the higher reactivity ratio of two kinds of the monomers. Two kinds of the monomers are so copolymerized that the degree of polymerization of the copolymer obtained by the copolymerization reaction of two kinds of the monomers attains <=97 wt.% when the reactivity ratios r1 and r2 satisfy r1/r2>=10 and attains <=92 wt.% when the reactivity ratios satisfy r1/r2<10.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a plastic optical transmission material used for, for example, a plastic optical fiber core, and more particularly to a method for producing a plastic optical transmission material by copolymerizing two kinds of monomers having different reactivity ratios. To a method for producing a plastic optical transmission material.

[0002]

2. Description of the Related Art It has been known to produce a plastic optical transmission material by copolymerizing two kinds of monomers having different reactivity ratios. For example, Japanese Patent Publication No. Hei 6-38125 discloses that a material containing two types of monomers having different refractive indices and reactivity ratios and a photopolymerization initiator is placed in a container, and the material is irradiated with light. A method for producing a plastic optical transmission material by copolymerizing monomers is disclosed.

[0003]

However, according to the manufacturing method described in the above-mentioned conventional gazette, the scattering loss of the manufactured plastic optical transmission material becomes large, and the core and the like of the plastic optical fiber are formed by using the material. In some cases, the transmission loss of the plastic optical fiber becomes large.

The present invention has been made in view of the above circumstances, and has as its object to provide a method of manufacturing a plastic optical transmission material capable of sufficiently reducing transmission loss in a plastic optical fiber or the like.

[0005]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies to solve the above-mentioned problems, and as a result, the cause of the increase in the scattering loss of the plastic optical transmission material is that the copolymerization of two types of monomers causes plastic optical transmission. It has been found that many domains such as block copolymers and homopolymers are formed in the transmission material. Further, such a domain is the product of the reactivity ratios r1, r2 of the two monomers (r
1 * r2) is formed more when the value is outside the range of 0.8 to 1.2, and it has been found that this domain increases the scattering loss of the plastic optical transmission material.

In the present invention, therefore, the reactivity ratios r1 and r2 satisfy the following formula: r1 × r2 <0.8 or r1 × r2> 1.2 (1), and r1 is smaller than 1 and r2 is 1 In a method for producing a plastic optical transmission material obtained by copolymerizing two larger monomers, a monomer having a lower reactivity ratio is used for 100 parts by weight of a monomer having a higher reactivity ratio among the two monomers. When the reactivity ratios r1 and r2 satisfy the following equation, r2 / r1 ≧ 10, 20 parts by weight or more and 10 parts by weight
Less than 0 parts by weight, and the reactivity ratios r1 and r2 become
When r1 <10 is satisfied, it is larger than 100 parts by weight and 5
The first step of adding only 00 parts by weight or less, and the polymerization degree of the product obtained by the copolymerization reaction of the two types of monomers is 97 wt% when the reactivity ratios r1 and r2 satisfy the following formula: r2 / r1 ≧ 10. %, The reactivity ratios r1, r2
When the following formula r2 / r1 <10 is satisfied, a second step of copolymerizing two kinds of monomers so as to be 92 wt% or less is provided. In the present invention, the degree of polymerization is defined by the following formula.

Degree of polymerization (wt%) = 100−100 × (weight of residual monomer component removed / weight of copolymerization product before removing residual monomer component) (2) According to the present invention, the reaction With respect to a monomer having a reactivity ratio of less than 1, the amount of the monomer having a reactivity ratio of greater than 1 is set in a predetermined range according to the magnitude of r2 / r1, and two types of monomers are added according to the magnitude of r2 / r1. By performing copolymerization so that the degree of polymerization of the product obtained by the copolymerization reaction becomes equal to or less than a predetermined value, it becomes possible to sufficiently prevent the progress of polymerization of the remaining monomer components. Therefore, the generation of domains such as a homopolymer and a block copolymer by the residual monomer component is sufficiently prevented, and the scattering loss of the obtained plastic optical transmission material is sufficiently reduced.

Preferably, the method further comprises, after the second step, a step of removing residual monomer components in the product obtained in the second step. The presence of the residual monomer causes air bubbles when drawing the plastic optical transmission material, and the air bubbles cause an increase in optical transmission loss in the obtained plastic optical fiber or the like. Therefore, after the second step, by removing the residual monomer component in the product obtained in the second step in advance, it is possible to more sufficiently prevent an increase in transmission loss of a plastic optical fiber or the like.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a method for producing a plastic optical transmission material according to the present invention will be described.

In the production method of the present invention, two kinds of monomers having different reactivity ratios, that is, a monomer having a reactivity ratio r1 smaller than 1 and a monomer having a reactivity ratio r2 larger than 1 are prepared (first step). ). Here, the present invention is effective when two kinds of monomers having reactivity ratios r1 and r2 satisfying the following formula: r1 × r2 <0.8 or r1 × r2> 1.2 (1) are used.
This is because a domain such as a homopolymer or a block copolymer is easily formed particularly when r1 × r2 is within the above range. Examples of a combination of two types of monomers having a reactivity ratio satisfying the above formula (1) include, for example, 3,
3,3-trifluoro-2-methyl-2-trifluoromethylpropyl methacrylate (r1 = 0.71), hexafluoroisopropyl-2-fluoroacrylate (r2 = 1.08), vinyl benzoate (r1 = 0. 0
7) and methyl methacrylate (r2 = 8.52), or a combination of methyl methacrylate (r1 = 0.95) and benzyl methacrylate (r2 = 1.07).

In the case of copolymerizing the above two monomers, the monomer having the higher reactivity ratio is charged into a container, and the monomer having the lower reactivity ratio is added to 100 parts by weight of the monomer having the higher reactivity ratio. Is the ratio of r2 to r1 (r2 /
The following amount is added according to the size of r1) (second step). That is, the reactivity ratios r1 and r2 satisfy the equation r2 / r1 ≧ 1.
0, the monomer having the lower reactivity ratio is added to 20
More than 100 parts by weight is added. The reason for this is that if the amount of the monomer having the lower reactivity ratio is less than 20 parts by weight, the monomer having the higher reactivity ratio forms a homopolymer and causes an increase in scattering. The reason is that the monomer having the lower reactivity ratio forms a homopolymer and causes an increase in scattering.

The reactivity ratios r1 and r2 are given by the following equation: r2 / r
When 1 <10, more than 100 parts by weight and 500
Add only parts by weight or less. This is because, when the amount of the monomer having the lower reactivity ratio is 100 parts by weight or less, the monomer having the higher reactivity ratio forms a homopolymer and causes an increase in scattering. If it exceeds, the monomer having the lower reactivity ratio forms a homopolymer and causes an increase in scattering.

In the copolymerization of the above two kinds of monomers, a polymerization initiator, a chain transfer agent and the like are added as required. In this case, examples of the polymerization initiator include 1,1-bis (t-butylperoxy) 3,3,5-trimethylcyclohexane, dialkyl peroxide, diacyl peroxide, peroxyketal, and di-t-butyl peroxide. Radical polymerization initiators such as peroxyester-based peroxides such as (perbutyl D). As the chain transfer agent, a mercapto group-containing compound, for example, n-
Butyl mercaptan, lauryl mercaptan, n-octyl mercaptan, n-butyl mercaptoacetate, isooctyl mercaptoacetate, methyl mercaptoacetate and the like.

In the copolymerization of two kinds of monomers, the degree of polymerization of a product obtained by the copolymerization reaction of two kinds of monomers is in the following range according to the ratio of r2 to r1 (r2 / r1). (Third step). That is,
When the reactivity ratios r1 and r2 satisfy the formula r2 / r1 ≧ 10, copolymerization is performed so that the degree of polymerization of the product is 97 wt% or less. This is because, when two types of monomers are copolymerized so that the degree of polymerization of the product exceeds 97 wt%, the copolymerization reaction between the two types of monomers proceeds to a considerable extent, and the block copolymer causes light scattering loss. And a large amount of homopolymers.

On the other hand, the reactivity ratios r1 and r2 are given by the formula r2 / r1
When <10 is satisfied, the degree of polymerization of the product is 92 wt%.
The copolymerization is performed as follows. This is because when two types of monomers are copolymerized so that the degree of polymerization of the product exceeds 92 wt%, the copolymerization reaction between the two types of monomers proceeds to a considerable extent, and the block copolymer causes light scattering loss. And a large amount of homopolymers. The degree of polymerization of the product is preferably not less than 60 wt% irrespective of the magnitude of the reactivity ratio (r2 / r1). Degree of polymerization is 60wt
If it is less than%, the molecular weight distribution is widened and the molecular weight is not increased, and the mechanical strength of the product tends to decrease.
Here, the degree of polymerization is defined by the following equation.

Degree of polymerization (wt%) = 100−100 × (weight of removed residual monomer component / weight of copolymerized product before removing residual monomer component) (2) The degree of polymerization is, for example, the polymerization time and the polymerization time. The desired value can be controlled by adjusting the polymerization temperature, adding an initiator, and adding a reaction terminator. When adjusting the polymerization time and the polymerization temperature, the polymerization time is usually from 6 to 30 hours, and the polymerization temperature is usually from 6 to 30, although it depends on the type of the monomer used.
0-180 ° C. As the reaction terminator, for example, hydroquinone or the like is used.

The degree of polymerization is determined by, for example, measuring the weight ratio of the residual monomer component in the product before removing the residual monomer component by gas chromatography (GC), and substituting the same into the above equation (2). Can be calculated and confirmed.

Thus, a plastic optical transmission material can be obtained by copolymerizing two kinds of monomers. At this time, since the polymerization is not completed in the plastic optical transmission material, a residual monomer component is included. If the residual monomer component is present in the plastic optical transmission material, it causes air bubbles when drawing the plastic optical transmission material. Therefore, it is preferable to remove the residual monomer component in the product before drawing the plastic optical transmission material as the product. By removing the residual monomer component, it is possible to sufficiently prevent the generation of bubbles at the time of drawing, and it is possible to more sufficiently prevent the transmission loss of a plastic optical fiber or the like from increasing.

As a method for removing the residual monomer component, for example, after dissolving the plastic optical transmission material in a predetermined solvent, another type of solvent is added and the copolymer among the plastic optical transmission materials is selectively recycled. The method of making it settle is mentioned.

As a solvent capable of dissolving the plastic optical transmission material, for example, tetrahydrofuran (TH)
F), acetone, methyl ethyl ketone (MEK) and the like. Further, as a solvent for selectively reprecipitating the copolymer among the plastic optical transmission materials, for example, methanol can be mentioned.

Thus, a plastic optical transmission material from which the residual monomer component has been removed is obtained. This plastic optical transmission material is applicable to various optical transmission bodies, for example, cores and claddings of plastic optical fibers. Such an optical transmission body can be obtained by extruding the plastic optical transmission material by an extrusion method or the like.

Next, the contents of the present invention will be described more specifically with reference to examples.

[0023]

EXAMPLES (Example 1) As two kinds of monomers, 3,
3,3-trifluoro-2-methyl-2-trifluoromethylpropyl methacrylate (r1 = 0.71, hereinafter referred to as “HFNPMA”), and hexafluoroisopropyl-2-fluoroacrylate (r2 = 1.0
8, hereinafter referred to as “HFIP-2FA”). The value of the product r1 × r2 of the reactivity ratio of these monomers is 0.7
78.

Then, based on 20 parts by weight of HFIP-2FA, which is a monomer having a higher reactivity ratio, 100 parts by weight of HFNPMA, which is a monomer having a lower reactivity ratio, and 1,1-bis ( t-butyl peroxy)
3,3,5-trimethylcyclohexane (Perhexa 3
M) of 0.05 wt%, and 0.09 wt% of n-butyl mercaptan (n-BM) as a chain transfer agent.
The copolymerization reaction was performed at 5 ° C. for 24 hours.

Thus, a plastic optical transmission material was obtained.
When the content of the residual monomer component of this material was measured using gas chromatography (GC), the content of the residual monomer component in the plastic optical transmission material was 8.35 wt%, and the polymerization of the plastic optical transmission material was performed. The degree was 91.65 wt%. The contents of HFNP-MA and HFIP-2FA in the plastic optical transmission material were 8.33 wt% and 0.02 wt%, respectively.

The plastic optical transmission material thus obtained is dissolved using a THF solvent, and then methanol is added to re-precipitate the plastic optical transmission material. The plastic optical transmission material is taken out to remove residual monomer components from the plastic optical transmission material. Was removed.

The plastic optical transmission material thus obtained was dried under reduced pressure at 100 ° C. for 24 hours, and the plastic optical transmission material was put into an extruder and extruded as a plastic optical fiber core material (diameter: 425 μm).
On the other hand, based on 100 parts by weight of HFIP-2FA, 0.2% by weight of di-t-butyl peroxide (perbutyl D) as a polymerization initiator and 0.3% by weight of isooctyl mercaptoacetate as a chain transfer agent were added and polymerized. The polymer is charged into an extruder, and the polymer is placed in a cladding material (inner diameter of 42).
(5 μm, thickness 500 μm). At this time,
The core material and the clad material were multiple-extruded simultaneously.

Then, a plastic optical fiber was obtained from the core material and the clad material. With respect to the plastic optical fiber thus obtained, the light transmission loss for 650 nm light was measured using a white light source (AQ-4303B, manufactured by Ando Electric Co., Ltd.) and a spectrum analyzer (AQ-6315B, manufactured by Ando Electric Co., Ltd.). As a result, it was found that the optical transmission loss was 70 dB / km, which was considerably low.

Comparative Example 1 HFIP-2FA and HFNP
MA was copolymerized at a polymerization temperature of 120 ° C. for a polymerization time of 48 hours to substantially complete the copolymerization reaction (degree of polymerization: 99 wt.
%) Except that a plastic optical fiber was obtained in the same manner as in Example 1. The optical transmission loss of the obtained plastic optical fiber was measured in the same manner as in Example 1. As a result, it was found that the optical transmission loss was 250 dB / km, which was considerably larger than that of Example 1. .

From the above, it is considered that when the copolymerization reaction is completed, HFNPMA having low reactivity forms a domain in the late stage of the polymerization, and this domain increases the transmission loss of the plastic optical fiber.

[0031]

As described above, according to the method for producing a plastic optical transmission material of the present invention, when two types of monomers having different reactivity ratios are copolymerized, formation of a domain such as a homopolymer or a block copolymer occurs. Is sufficiently prevented, and the scattering loss of the obtained plastic optical transmission material is reduced, so that the transmission loss of a plastic optical fiber or the like can be sufficiently reduced.

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Claims (2)

[Claims] 1. Two types of reactive ratios r1 and r2 satisfy the following formula: r1 × r2 <0.8 or r1 × r2> 1.2 (1), and r1 is smaller than 1 and r2 is larger than 1. In the method for producing a plastic optical transmission material obtained by copolymerizing the monomers of the above, the monomer of the lower reactivity ratio to 100 parts by weight of the higher reactivity monomer of the two types of monomers,
When the reactivity ratios r1 and r2 satisfy the following formula r2 / r1 ≧ 10, they are added in an amount of 20 to less than 100 parts by weight. When the reactivity ratios r1 and r2 satisfy the following formula r2 / r1 <10, 100 is added. A first step of adding more than 500 parts by weight and more than 5 parts by weight, and a degree of polymerization of a product obtained by a copolymerization reaction of the two types of monomers, wherein the reactivity ratios r1 and r2 satisfy the following formula: r2 / r1 ≧
When the two types of monomers are copolymerized, the reactivity ratios r1 and r2 become 92 wt% or less when the following formula r2 / r1 <10 is satisfied. A method for producing a plastic optical transmission material, comprising: two steps. 2. The production of a plastic optical transmission material according to claim 1, further comprising, after the second step, a step of removing a residual monomer component in a product obtained in the second step. Method.