JPH08199067A - Organopolysiloxane composition for plastic optical fiber and production of plastic optical fiber therefrom - Google Patents

Abstract

PURPOSE: To obtain an organopolysiloxane compsn. which is used for a plastic optical fiber, has a low viscosity, can be easily poured into a cladding material in the shape of a tube, and converts, when heated after the pouring, into a high-viscosity organosiloxane suitable as a core material. CONSTITUTION: This compsn. comprises an organopolysiloxane having on average two alkenyl groups per molecule, an organopolysiloxane having on average two silicon-bonded hydrogen atoms per molecule, and a platinum-group metal catalyst, has a viscosity of 5,000cP or lower at 25 deg.C, and converts, when heated, into an organopolysiloxane having a viscosity of 10,000cP or higher at 25 deg.C and a viscosity of a 10wt.% toluene soln. of 50,000cSt or lower.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an organopolysiloxane composition suitable as a core material for plastic optical fibers and a method for producing plastic optical fibers using the same.

[0002]

2. Description of the Related Art As is well known, silica glass and multi-component glass are used for optical fibers in a core component and a clad (sheath).
There is a glass-based optical fiber as a component. Although plastic optical fibers have the disadvantage of having a larger transmission loss than glass-based optical fibers, they have the advantages of easier numerical aperture, easier handling, and lower cost than glass-based optical fibers. .

A plastic optical fiber is usually composed of a core made of an organic polymer having a high light transmittance, and a clad made of an organic polymer having a smaller refractive index and higher transparency than the core. In this case, polymethyl methacrylate, polystyrene and the like are known as an organic polymer having a good light transmittance which is suitable as the core substance. Furthermore, in recent years, it has been proposed in JP-A-60-43613 to use an organopolysiloxane elastic body as a core substance, and a plastic optical fiber using this as a core substance has polymethylmethacrylate or the like as a core component. It has the advantage of being more flexible and superior in heat resistance than those of the products.

[0004]

In the optical fiber using the elastic material of organopolysiloxane as a core material, a fluorine-based resin having a low refractive index and high heat resistance is usually used as a clad material due to the requirement of heat resistance. As a result, there is a drawback that the adhesive force between the core and the clad is low. As a result, external force such as bending or lateral pressure acts on the fiber, or stress is generated between the clad and the core having different expansion coefficients due to heating and cooling. As a result, delamination easily occurs at the interface between the core and the clad. This delamination can occur not only after the fiber is manufactured, but also during manufacturing. This is because, in general, an optical fiber having an organopolysiloxane elastic body as a core is obtained by press-fitting a liquid organopolysiloxane composition, which can be cured into an elastic body by heating, into a tubular clad material made of a fluororesin and then heating it. This is because the above-mentioned stress acts on the interface even in the manufacturing process because the film is cured and then manufactured. Since such peeling adversely affects the transmission characteristics of the optical fiber, the reliability of the obtained optical fiber is not satisfactory.

The present invention has been made in view of the above problems, and is suitable for the preparation of an organopolysiloxane core material in which stress is not generated between the core material and the clad material, and therefore there is no fear of peeling. It is an object of the present invention to provide an organopolysiloxane composition for plastic optical fibers, and a method for producing an optical fiber using the same.

[0006]

Means for Solving the Problems The inventors of the present invention have conducted extensive studies to achieve the above object, and as a result, (a) an organopolysiloxane having an average of two alkenyl groups in one molecule,
(B) The average number of hydrogen atoms bonded to silicon atoms in a molecule is 2
A composition having an organopolysiloxane having a number of (c) and a platinum group metal-based catalyst, and having a viscosity at 25 ° C. of not more than 5000 centipoise and having a viscosity at heating of 25 ° C. of not less than 10,000 centipoise, And
Viscosity of 50,000 in 10 wt% toluene solution
It has been found that an organopolysiloxane composition that produces an organopolysiloxane that is less than a centistoke is effective as a core material for plastic optical fibers. That is, this composition has a low viscosity of 5000 centipoise or less, which is advantageous for filtration and purification when being pressed into a tubular clad material, but when heated after being pressed, the alkenyl group of component (a) and the component (b) of A hydrogen atom undergoes an addition reaction due to the catalytic action of the component (c) and is converted into a highly viscous liquid organopolysiloxane, which has a high degree of polymerization suitable as a core material but is not an elastic body.

The present invention will be described in more detail below. (A) alkenyl group-containing organopolysiloxane ( ii ) The organopolysiloxane used as the component is
It is an organopolysiloxane having an average of two, preferably two alkenyl groups in one molecule, and the structure is not limited and may be linear or branched. For example, the average composition formula (1)

Embedded image (R ¹ ) _a (R ² ) _b SiO _{(4-ab) / 2} (1) (where a and b are positive integers, where 0 <a +
b <4, preferably 1.8 ≦ a + b ≦ 2.3). Among them, organosiloxane
Preferred as (a) is a linear diorganopolysiloxane having an alkenyl group at the molecular chain end. Although the viscosity of this diorganopolysiloxane is not limited,
Low viscosities are preferred.

Examples of the alkenyl group contained in the organopolysiloxane include a vinyl group, an allyl group and a hexenyl group, and a vinyl group is preferable. The average number of alkenyl groups contained in one molecule is two.
When the number of alkenyl groups is less than 2, the organopolysiloxane produced by heating does not have the required high viscosity (high degree of polymerization), and when it is more than 2, the organopolysiloxane becomes gel or rubber-like. Does not become a freely deformable fluid.

Examples of the organic group other than the alkenyl group possessed by the organosiloxane include alkyl groups such as methyl group, ethyl group and propyl group, cycloalkyl groups such as cyclohexyl group, aryl groups such as phenyl group, tolyl group and xylyl group. , A benzyl group, a monovalent hydrocarbon group such as an aralkyl group such as a phenylethyl group, a tetrachlorophenyl group or a chlorophenyl group in which at least a part of hydrogen atoms of these hydrocarbon groups are substituted with a halogen atom such as fluorine or chlorine. And halogen-substituted monovalent hydrocarbon groups such as chloromethyl group, pentafluorobutyl group and trifluoropropyl group. Of these, a methyl group and a phenyl group are preferable.

A preferred example of this organopolysiloxane (a) is ViMe ₂ SiO (Me ₂ SiO) _a S
iMe ₂ Vi, ViMe ₂ SiO (Me ₂ SiO)
_b (MePhSiO) _c SiMe ₂ Vi, ViMe ₂ S
iO (Me ₂ SiO) _d (Ph ₂ SiO) _e SiMe ₂
Vi, ViMe ₂ SiO (ViMeSiO) (Me ₂ S
iO) _f (Ph ₂ SiO) _g --- SiMe ₃ , Me ₃ S
iO (ViMeSiO) ₂ (Me ₂ SiO) _h (Ph ₂
SiO) _i --- SiMe ₃ (wherein Vi is a vinyl group,
Me is a methyl group, Ph is a phenyl group, a, b,
c, d, e, f, g, h and i are all 0 or a positive integer) and the like. These may be used alone or in combination of two or more.

(B) Organosiloxane containing Si--H group (b) An organopolysiloxane having an average of two hydrogen atoms bonded to a silicon atom, preferably two hydrogen atoms in one molecule, which is used as the component, is, for example, Average composition formula:

Embedded image (R ² ) _c H _d SiO ² _{(4-cd) / 2} (where c and d are positive integers, where 0 <c +
d <4, preferably 1.8 ≦ c + d ≦ 2.3 is satisfied)
It is represented by. The structure of the organosiloxane (b) is not particularly limited, and may be linear or branched, but a linear diorganopolysiloxane having the hydrogen atom at the molecular chain terminal is preferable. The viscosity of the organosiloxane (B) is not particularly limited, but generally low viscosity is preferable.

Examples of the organic group contained in the organosiloxane (b) include organic groups other than the alkenyl group among the organic groups exemplified for the component (a). A preferred example of the organosiloxane (B) is HMe ₂ SiO _2.
(Me ₂ SiO) _f SiMe ₂ H, HMe ₂ SiO (M
e ₂ SiO) _g (MePhSiO) _h SiMe ₂ H, H
Me ₂ SiO (Me ₂ SiO) _i (Ph ₂ SiO) _j S
iMe ₂ H (wherein Vi is a vinyl group, Me is a methyl group, Ph is a phenyl group, and f, g, h, i, and j are 0.
Or a positive integer). The content of the component (b) in the composition of the present invention is such that the component (b) has a high degree of polymerization showing a required viscosity upon heating so that the component (b) can be added to one mole of the alkenyl group of the component (b). Has an amount of hydrogen atoms bonded to silicon atoms of 0.5 to 2.
It is preferably in the range of 0, particularly preferably about 1 mol.

(C) Platinum group metal-based catalyst (C) As the platinum group metal-based catalyst used as the component,
Examples of the catalyst include platinum, palladium, rhodium and the like, and a platinum-based catalyst is preferable. Examples of platinum catalysts include platinum black and chloroplatinic acid. Chloroplatinic acid is
In order to improve the compatibility with the components (a) and (b), it is preferable to use it as a solution such as an alcohol-modified solution of chloroplatinic acid or a silicone-modified solution of chloroplatinic acid.
The amount of the platinum-based catalyst as the component (c) may be a so-called catalytic amount. In particular,
Since platinum acts to increase the optical transmission loss, it is better that the amount of platinum is smaller. Specifically, the amount of platinum is preferably 5 ppm or less with respect to the total amount of the components (a) and (b), particularly 0 It is preferably set to 0.01 ppm to 1 ppm.

Other Components The composition of the present invention comprises the above-mentioned component (a), component (b) and
(C) Obtained by mixing the components, and by mixing (C)
Due to the catalytic action of the platinum-based catalyst as the component, the addition reaction between the component (a) and the component (b) proceeds even at around room temperature, but this reaction may be performed under heating at 100 to 150 ° C. In that case, you may add a reaction inhibitor as needed in order to improve workability. Examples of the reaction inhibitor include, in addition to acetylene alcohols, 3-methyl-3-butyn-2-ol, 2-methyl-1-pentyl-3-ol, 3,5-dimethyl-1-hexyne-3-ol. ,
2,5-dimethyl-3-hexyne-2,5-diol,
3,6-dimethyl-4-octyne-3,6-diol,
2,4,7,9-Tetramethyl-5-decyne-4,7-
Examples include diols. The amount of the reaction inhibitor added is not particularly limited and may be appropriately selected according to the working conditions.

The composition of the present invention must be previously filtered and refined with a fine filter so that a high transmission performance can be obtained after it becomes an optical fiber core. Therefore,
If the viscosity is too high, the filtration rate becomes slow and the productivity is impaired. Therefore, the viscosity (25 ° C.) of the composition is preferably 5000 cP or less. As will be described later, this composition is required to form a highly viscous organosiloxane having a viscosity of 10,000 cP or more at 25 ° C. in the finally obtained optical fiber. This high-viscosity organosiloxane functions as a core material for optical fibers, and when the viscosity is less than 10000 cP,
There is a risk of leakage through the clad material. On the other hand, this high-viscosity organopolysiloxane has a viscosity of 50,000 cSt or less in a 10 wt% concentration toluene solution. It is difficult to manufacture a product having a viscosity of higher than 50,000 cSt in the toluene solution state.

By the way, a high-viscosity organopolysiloxane is usually produced by polymerizing a cyclic siloxane with an alkali catalyst, neutralizing the catalyst, and removing the neutralized salt by filtration. In order to apply it as a core material, it is necessary to use a very fine filter from the viewpoint of transmission characteristics in filtration and purification. However, in this ordinary production method, it is necessary to filter the high-viscosity organopolysiloxane, which causes a problem that the filtration takes an excessively long time and the filtration itself is extremely difficult. On the other hand, in the case of the composition of the present invention, since it has a relatively high viscosity, it has an advantage that filtration is easy and injection into the clad material after filtration is easy.

Production of Plastic Optical Fiber The composition of the present invention is prepared as described above, filtered and purified with an appropriate filter, and then provided for production of a plastic optical fiber. The optical fiber of the present invention is a plastic optical fiber comprising a core material made of organosiloxane and a clad material made of a fluororesin having a refractive index lower than that of the organosiloxane, and the optical fiber is made of the fluororesin. It can be produced by press-fitting the above organopolysiloxane composition into a tube and then heating. The heating converts the composition to the organosiloxane having the high viscosity specified above.

The fluororesin used as the clad material is selected such that its refractive index is lower than that of the high-viscosity organopolysiloxane that is produced by heating and becomes the core material. Examples of the fluorine-based resin used as the clad material include polytetrafluoroethylene, tetrafluoroethylene / perfluoroalkyl vinyl ether copolymer, tetrafluoroethylene / hexafluoropropylene copolymer, polychlorotrifluoroethylene, tetrafluoroethylene. / Ethylene copolymer, polyvinyl fluoride, polyvinylidene fluoride, tetrafluoroethylene / vinylidene fluoride copolymer.

[0019]

EXAMPLES The present invention will be specifically described below with reference to examples. Parts mean parts by weight, and the viscosity is the value measured at 25 ° C. 0.405 wt% of vinyl groups in Example -1 molecular chain terminal, linear methylvinyl polysiloxane 100 parts of formulas and to the number contains two per molecule _{(1): HMe 2 SiOPh 2} SiOSiMe 2 H (1) (wherein Me represents a methyl group) 2.57 parts of a polysiloxane having a hydrogen atom bonded to a silicon atom at the end of the molecular chain is mixed, and platinum chloride is added to the total weight of the mixture. An octyl alcohol-denatured solution of the acid was added and mixed as platinum to 0.02 ppm. The mixture was filtered with a filter having a diameter of 0.2 μm to give a viscosity of 5
A 90 cP composition was obtained. This composition has an inner diameter of 1.5 mm,
The composition was press-fitted into a FEP (tetrafluoroethylene-hexafluoropropylene copolymer) tube having an outer diameter of 2 mm, and the composition was heated at 150 ° C. for 24 hours under a pressure of about 1 kgf / cm ² . Separately, this composition was placed in a glass container and heated at 150 ° C. for 24 hours. The product does not flow easily after heating Gum-like organopolysiloxane (viscosity of a 10 wt% toluene solution:
It was 260 cSt). In the plastic optical fiber obtained above, no peeling was observed between the clad made of FEP tube and the core made of organopolysiloxane. Further, this optical fiber was wound around a cylinder having a diameter of 10 mm, but no peeling was observed between the clad and the core.

Example-2 The following formula (2): ViMe ₂ SiOSiPh ₂ OSiMe ₂ Vi (2) (wherein, Vi is a vinyl group, Me is a methyl group, and Ph is a phenyl group). A straight-chain methylhydrogenpolysiloxane containing 3.2 parts of a group-containing organopolysiloxane and 0.0167% by weight (two per molecule in terms of number) of hydrogen atoms bonded to silicon atoms at the end of the molecular chain. 100 parts of the mixture was mixed, and an octyl alcohol-modified solution of chloroplatinic acid was added and mixed so that the platinum content was 0.02 ppm with respect to the total weight of the mixture. This mixture was filtered in the same manner as in Example-1 to obtain a composition having a viscosity of 480 cP. The obtained mixture was pressed into an FEP tube and heated in the same manner as in Example 1 to obtain a plastic optical fiber. When heated in a glass container in the same manner as in Example 1, the product after heating was a gum-like organopolysiloxane (viscosity of 10 wt% toluene solution: 210 cSt). Further, in the optical fiber obtained above, no peeling was observed between the FEP tube of the clad and the core made of organopolysiloxane, and even if it was wound around a cylinder with a diameter of 10 mm, the clad was separated from the core. No peeling occurred.

Comparative Example-1 100 parts of a linear methylvinylpolysiloxane containing 0.0142% by weight of vinyl group at the end of the molecular chain (two per molecule in terms of number) and hydrogen bonded to a silicon atom. 0.74% by weight of atoms (10 per molecule on average)
Methyl hydrogen polysiloxane containing 2.87
Parts, and 0.02 pp of octyl alcohol modified solution of chloroplatinic acid as platinum based on the total weight of the mixture.
The mixture was added and mixed so as to obtain m. This mixture was used as Example-1.
The mixture was filtered in the same manner as in 1. to obtain a composition having a viscosity of 720 cP. A plastic optical fiber was produced from the obtained composition in the same manner as in Example-1. In the obtained optical fiber, the obtained core material was an elastic body having no fluidity, and peeling was observed in places with the clad material. Further, when the unpeeled portion was wound around a 10φ cylinder, peeling occurred. Separately
This composition was poured into a glass container and heated at 150 ° C. for 24 hours to obtain a cured product having rubber-like elasticity. When the hardness of this cured product was measured by an A-type spring hardness tester according to JIS-K6301, the hardness was 28.

[0022]

The composition for plastic optical fibers of the present invention has a low viscosity of 5000 cP or less, so that it can be easily injected into a tube serving as a clad material, and a high-viscosity organoorganic material suitable as a core material by heating after injection. It is advantageous for the production of plastic optical fibers because it produces siloxane. According to the production method of the present invention, since a composition having a high fluidity and a low viscosity is used for injecting the clad material, workability is high, while a high-viscosity organosiloxane obtained as a core material by subsequent heating is sufficiently high. Since it has a high viscosity, it does not flow out from the tube of the clad material, and since it has a fluidity that can be freely deformed, peeling due to stress occurs between the cladding material and the core material made of an elastic body. There is no.

Claims (3)

[Claims] 1. (a) An organopolysiloxane having an average of 2 alkenyl groups in one molecule, and (b) an average of 2 hydrogen atoms bonded to a silicon atom in one molecule.
A composition having an organopolysiloxane having a number of (c) and a platinum group metal-based catalyst, and having a viscosity at 25 ° C. of not more than 5000 centipoise and having a viscosity at heating of 25 ° C. of not less than 10,000 centipoise, And in the state of 10 wt% concentration in toluene solution 25
An organopolysiloxane composition producing an organopolysiloxane having a viscosity at ℃ of 50,000 cSt or less. 2. The composition according to claim 1, comprising:
A composition in which the organopolysiloxane as a component has two alkenyl groups and the organopolysiloxane as a component (b) has two hydrogen atoms bonded to a silicon atom. 3. A method for producing a plastic optical fiber comprising a core material made of organopolysiloxane and a clad material made of a fluororesin having a refractive index lower than that of the organosiloxane. A method for producing a plastic optical fiber, which comprises press-fitting the organopolysiloxane composition according to claim 1 into a tube and then heating.