JPH0476390B2 - - Google Patents

Description

[Detailed description of the invention]

INDUSTRIAL APPLICATION FIELD The present invention relates to a silicone composition having workability, hardness and rubber elasticity suitable for use as a cladding layer of a silicone resin-clad optical communication fiber. PRIOR ART AND PROBLEMS TO BE SOLVED BY THE INVENTION One type of optical communication fiber is a so-called plastic fiber, which has a fibrous core of quartz glass or optical glass and a cladding layer of various polymeric materials on the outside of the core. There is a Tsudo optical communication fiber. The polymer material constituting the cladding portion of this plastic-clad optical communication fiber is selected to have a refractive index lower than that of the glass core. are used, among which silicone resins are widely used. As this silicone resin, a heat-curable organopolysiloxane composition consisting of dimethylpolysiloxane whose molecular ends are capped with vinyldimethylsiloxy groups, methylhydrogensiloxane, and a platinum catalyst is widely used. The hardness of the cured product of the composition is low, and when used as a cladding layer of an optical communication fiber, the fiber core may protrude from the cladding layer. Therefore, in order to increase the hardness of this cured silicone product in order to suppress the protrusion of the core wire, [(CH ₃ ) ₃ SiO _0.5 ] and [(CH ₂ =CH) (CH ₃ ) were added to the above composition.
It has been proposed to add a siloxane copolymer consisting of [SiO _0.5 ] and [SiO ₂ ]. However, in this method, it is necessary to add a large amount of this copolymer in order to make the hardness of the cured product higher than a certain level (for example, JIS hardness 60 or higher), which causes several drawbacks. One of its disadvantages is that the viscosity of the composition becomes very high, which makes it very difficult to apply the composition in liquid form to the core glass fiber. Furthermore, as the amount of copolymer in the composition increases, the cured product gradually loses its rubber elasticity, making it unable to follow the bending of optical communication fibers. The present invention was made in view of the above circumstances, and it is an object of the present invention to provide a silicone clad composition for optical communication fibers that has excellent workability, high hardness after curing, and excellent rubber elasticity. . Means and Effects for Solving the Problems In order to achieve the above object, the present inventors conducted extensive studies and found that the following general formula (1) is used as a vinyl siloxane. (R in the formula is a substituted or unsubstituted monovalent hydrocarbon group containing no aliphatic unsaturated group, a is the number of 0 or 1,
n is a positive integer) and (CH ₂
＝CH) _3-b Contains _0.5 units of RbSiO, _0.5 units of R ₃ SiO and 0.5 units of SiO ₂ , and (CH ₂ =CH) _3- with respect to the SiO ₂ units.
_b The sum of the molar ratio of RbSiO _0.5 units and R ₃ SiO _0.5 units is
0.5-2, and vinyl group content is 0.5-9% by weight
organopolysiloxane (in the formula of each unit R
is a substituted or unsubstituted monovalent hydrocarbon group having no aliphatic unsaturated bond, b is a number of 0, 1, or 2), the cured product can increase hardness while maintaining rubber elasticity. The inventors have discovered that this cured product exhibits excellent properties as a cladding layer of silicone resin-clad optical communication fibers, and can prevent the core wire from protruding, leading to the completion of the present invention. . In this case, it is important that the organopolysiloxane as component (A) of the present invention has a plurality of vinyl groups bonded to the silicon atoms at both ends of the linear organopolysiloxane, and is not simply a vinyl group. For example, in the following formula, one vinyl group is bonded to each terminal silicon atom for the sole purpose of making the amounts of (Here, R is the same as above, l and m are positive integers) Even if the organopolysiloxane shown is used, the same effect as using component (A) of the present invention cannot be obtained. It is. Therefore, the present invention provides (A) the following general formula (1) (In the formula, R is a substituted or unsubstituted monovalent hydrocarbon group containing no aliphatic unsaturated group, a is a number of 0 or 1, and n is a positive integer)
100 parts by weight, (B) Contains (CH ₂ = CH) _3-b RbSiO _0.5 unit, R ₃ SiO _0.5 unit and SiO ₂ unit, (CH ₂ = CH) _3-b RbSiO _0.5 unit relative to SiO ₂ unit Organopolysiloxane having a sum of molar ratios of _{0.5 to 0.5} units of R ₃ SiO and 0.5 to 2 and a vinyl group content of 0.5 to 9% by weight (R in the formula of each unit has no aliphatic unsaturated bond) (substituted or unsubstituted monovalent hydrocarbon group, b represents the number 0, 1, or 2) 5 to 150 parts by weight, (C) Organocarbons having two or more hydrogen atoms directly bonded to a silicon atom in one molecule It is characterized by containing polysiloxane in an amount sufficient to provide 0.7 to 5 hydrogen atoms directly bonded to silicon atoms per vinyl group in components A and B, and (D) platinum or a platinum compound in a catalytic amount. The present invention provides a silicone composition for optical communication fiber. The present invention will be explained in more detail below. As mentioned above, the organopolysiloxane as component (A) constituting the composition of the present invention has the following general formula (1). In the formula, a is a number of 0 or 1, and a plurality of vinyl groups are bonded to silicon atoms at both ends of a linear organopolysiloxane. In this case, the number of vinyl groups bonded to the silicon atoms at both ends may be two or three, but
It is preferable that the number is three in order to increase the hardness of the cured product. Here, the substituted or unsubstituted monovalent hydrocarbon group containing no aliphatic unsaturated group for R in general formula (1) includes alkyl groups such as methyl group, ethyl group, and propyl group, phenyl group, and tolyl group. Examples include aryl groups such as cyclohexyl groups, cycloalkyl groups such as cycloheptyl groups, and groups in which the hydrogen atoms bonded to the carbon atoms of these hydrocarbon groups are partially substituted with halogen atoms, cyano groups, etc. Although not particularly limited, it is preferable that all of the R groups are methyl groups or consist of a methyl group and a phenyl group. When the R group consists of a methyl group and a phenyl group, the quantitative ratio of the methyl group and phenyl group is such that the refractive index of the silicone composition as a cladding is lower than the refractive index of the outermost layer of the quartz glass or optical glass used as the core. The refractive index of the silicone composition can be changed as appropriate depending on the ratio of methyl groups to phenyl groups. Note that this organopolysiloxane only needs to be substantially linear, and may contain a branched portion in its molecule. In addition, n in formula (1) represents a positive integer, which is not particularly limited, but preferably has a value such that the viscosity of the organopolysiloxane at 25°C is 50 to 100,000 centistokes, More preferably, the value is 100 to 10,000 centistokes. Specifically, as the organopolysiloxane of component (A) etc. Next, the organopolysiloxane (B) component is (A)
It is a component that works together with the component organopolysiloxane to improve the hardness and mechanical strength of the cured product, and as mentioned above, (CH ₂ = CH) _3-b RbSiO _0.5
organopolysiloxanes containing R ₃ SiO _0.5 units and SiO ₂ units, where the R group is a substituted or unsubstituted monovalent hydrocarbon group containing no aliphatic unsaturation. Examples of this R group include the same groups as in the case of the R group in component (A) mentioned above, and as in the case of component (A), there are no particular limitations, but all of them are methyl groups. A methyl group and a phenyl group are preferred. Further, b is a number of 0, 1, or 2, but desirably b=2 for ease of synthesis. (CH ₂ = CH) _3-b RbSiO _0.5 for the SiO ₂ unit in this (B) component
The mole of the unit and R ₃ SiO _0.5 unit is 0.5 to 2,
Preferably it is 0.8 to 1.5. If this mole exceeds 0.5, synthesis is difficult, while if it is less than 2, it is not very effective in increasing the hardness of the cured product. In addition, the content of vinyl groups in this component (B) is 0.5 to 9
% by weight, preferably 0.7 to 5% by weight. If the content of this vinyl group is less than 0.5% by weight, the amount of component (B) in the composition must be relatively increased, which is inappropriate in relation to the amount of component (B) described later. be. On the other hand, if the amount exceeds 9% by weight, the hardness of the cured product will increase, but the mechanical strength will decrease and the product will become brittle. Note that this organopolysiloxane as component B may partially contain (CH ₂ =CH) RSiO units or R ₂ SiO units (R is a monovalent hydrocarbon group similar to the above R). do not have. Specifically, examples of the organopolysiloxane of component (B) include the following formulas (a) to (c). [(CH ₃ ) ₃ SiO _0.5 ] _1.1 [(CH ₂ = CH) (CH ₃ ) ₂ SiO _0.5
] _0.05 [SiO ₂ ] _1.0 ...(a) [(CH ₃ ) ₃ SiO0.5] _1.05 [(CH ₃ ) ₂ (C ₆ H ₅ ) SiO0.5]
_0.05 [(CH ₂ = CH) (CH ₃ ) ₂ SiO0.5] _0.05 [SiO ₂ ] _1.0 …
…(b) [(CH ₃ ) ₃ SiO0.5] _1.1 [(CH ₂ =CH) ₃ SiO0.5] _0.05
[SiO ₂ ] _1.0 ...(c) It is preferable to blend as much of this component (B) as possible in order to increase the hardness of the composition after curing, but if it is too large, the composition The viscosity of the product increases, making coating work difficult, and the rubber elasticity may be impaired, making it impossible to follow the bending of the fiber. It is preferably in the range of 25 to 120 parts by weight. The organohydrodiene polysiloxane of component (C) is a crosslinking agent for curing the composition by forming a crosslinking bond through an addition reaction with the vinyl groups in components (A) and (B). As mentioned above, one molecule has two or more hydrogen atoms directly bonded to a silicon atom. In this component (C), organic groups other than hydrogen atoms and oxygen atoms directly bonded to silicon atoms are not particularly limited, but are substituted or unsubstituted monovalent hydrocarbons that do not contain aliphatic unsaturated groups. The group is preferably a group, and the same groups as the R group in component (A) are exemplified, but it is more preferably a group consisting entirely of methyl groups or a methyl group and a phenyl group.
In addition, when the organic groups other than the hydrogen atom and oxygen atom directly bonded to the silicon atom are a methyl group and a phenyl group, the ratio of the methyl group and phenyl group is (A) and (B).
It can be determined by taking into account the solubility of component (C) in the components. Note that the organohydrodiene polysiloxane of component (C) may be in any form such as linear, branched, or cyclic because of its role as a crosslinking agent as described above. The viscosity of the organohydrodiene polysiloxane as component (C) greatly affects the fluidity of the composition and can therefore be determined from the fluidity of the composition.
Since the fluidity of the present composition is liquid and is applied to the fibrous glass core, it is not preferable whether the composition is too easy to flow or too difficult to flow. A material that is too fluid will flow down during the coating operation before the composition applied to the core is cured, whereas a material that is too fluid will not be coatable. For this reason, the preferred viscosity of the composition is 50 to 50 at 25°C.
100000 centistokes, more preferably
It is 100 to 10,000 centistokes. From this point of view, the viscosity of the organohydrodiene polysiloxane as component (C) is preferably 10 to 10,000 centistokes at 25°C. The amount of component (C) to be blended is sufficient to provide 0.7 to 5 hydrogen atoms directly bonded to silicon atoms per vinyl group in both components (A) and (B). When the amount of component (C) blended is small, sufficient crosslinking density cannot be obtained; on the other hand, when it is too large, a large amount of component (C) that does not participate in the crosslinking reaction will be contained in the composition. may deteriorate the physical properties of Furthermore, a catalytic amount of platinum or a platinum compound is blended as component (D) in the composition of the present invention, but this is due to the crosslinking caused by the addition reaction between components (A) and (B) and component (C). It is a catalyst for accelerating the production of and shortening the time required for curing, and platinum black, chloroplatinic acid, a complex of chloroplatinic acid with olefins, aldehydes, etc., or alcohol-denatured products are preferably used. The blending amount of component D is (A),
The amount should be adjusted as appropriate depending on the type of components (B) and (C), the desired curing speed, etc., but in general, (A),
The weight ratio of platinum metal to the total of components (B) and (C) is 0.1 to 300 ppm, preferably 0.5 to 100 ppm. The composition of the present invention can be obtained by simply uniformly mixing the components (A), (B), (C), and (D) described above, but the present invention further includes various additives. For example, vinyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-aminopropyltrimethoxysilane, etc. may be added to improve the adhesion at the interface between the core glass and the composition. So-called carbon functional silanes can be added. Further, if necessary, a compound such as phosphorus, nitrogen, sulfur, or an acetylene compound may be added to control the addition reaction. In order to obtain a cladding layer of an optical communication fiber using this composition, the composition may be applied to the core surface and cured by heating. The composition of the present invention is not only suitable as a cladding for optical communication fibers, but also
It can be suitably used as a primary coating material for optical communication fibers in which both the core and cladding parts are made of silica glass, and also as a secondary coating material (buffer) coated on the primary coating. Effects of the Invention The silicone composition for optical communication fibers of the present invention has excellent workability due to the above-mentioned structure, and its cured product has excellent hardness and rubber elasticity, making it suitable as a silicone cladding for optical communication fibers. It has certain characteristics. EXAMPLES Hereinafter, the present invention will be specifically explained with reference to Examples and Comparative Examples, but the present invention is not limited to the following Examples. In addition, in the following examples, parts indicate parts by weight. Example 1 100 parts of a linear dimethylpolysiloxane having a viscosity of 400 centistokes at 25° C. and having trivinylsiloxy groups at both ends was mixed with the formula [(CH ₃ ) ₃ SiO _0.5 ] _1.1 [(CH ₂ =CH)(CH ₃ ) _{2SiO 0.5}
] _0.05 [SiO ₂ ] Methylvinylsiloxane copolymer shown as _1.0
120 parts, 7.1 parts of methylhydrodiene polysiloxane containing 1.06 mol/100 g of -SiH bonds, 0.05 part of an octyl alcohol modified solution of chloroplatinic acid (platinum content 2% by weight), and 0.05 part of a siloxane modified solution of acetylene alcohol. In addition, they were mixed uniformly to obtain a silicone composition for optical communication fiber. The viscosity of this composition is approximately 2000 centistokes at 25°C, and the hardness of the cured product according to JIS-K6301 is
It was 80. Next, a quartz glass core was melt-spun to a diameter of 200 μm, and the composition of this example was applied onto the core through a coating die and cured by heating in a heating furnace, resulting in a coating film with a uniform surface as a cladding layer. Obtained. Comparative Example 1 In place of the linear dimethylpolysiloxane with both ends blocked by trivinylsiloxy groups in Example 1,
Polysiloxane with vinyldimethylsiloxy groups blocked at both ends, with an average of methylvinylsiloxane units in one molecule.

Contains 4 moles of [Formula], the remainder The remainder is dimethylsiloxane unit

A silicone composition for optical communication fibers was obtained in the same manner as in Example 1, except that 100 parts of a linear polysiloxane having a viscosity of about 400 centistokes at 25° C. was used. This composition has a viscosity of approximately 2000 centistokes at 25°C and a hardness of the cured product according to JIS-K6301.
75, which was almost the same as the composition of Example 1, but
The rubber elasticity of the cured product was low, and when a coating experiment similar to that in Example 1 was conducted, the coating surface was brittle and peeled off from the glass surface during fiber winding. Comparative Example 2 100 parts of a linear dimethylpolysiloxane having a viscosity of about 400 centistokes at 25° C. and having a vinyl dimethylsiloxy group endblocking at both ends was used in place of the linear dimethylsiloxane in Example 1 with a trivinylsiloxy group endblocker at both ends. , formula [(CH ₃ ) ₃ SiO _0.5 ] _1.1 [(CH ₂ =CH)(CH ₃ ) ₂ SiO _0.5
] _0.05 [SiO ₂ ] A silicone composition for optical communication fiber was obtained in the same manner as in Example 1, except that 200 parts of the methylvinylpolysiloxane copolymer represented by _1.0 was used. The viscosity of this composition was approximately 2 million centistokes at 25°C, and the hardness of the cured product was 90 according to JIS-K6301. The composition of this example had too high a viscosity and could not be coated onto the quartz core. Example 2 100 parts of a linear dimethylpolysiloxane having a viscosity of about 2000 centistokes at 25° C. and having trivinylsiloxy groups at both ends of the molecule were added with the formula [(CH ₃ ) ₃ SiO _0.5 ] _1.1 [(CH ₂ =CH) _{( CH3} ) _2SiO0.5
] _0.05 [SiO ₂ ] Methyl vinyl siloxane copolymer 33 shown as _1.0
%, 6.6 parts of methylhydrodiene polysiloxane containing 1.06 mol/100 g of SiH bonds, 0.05 part of an octyl alcohol modified solution of chloroplatinic acid (platinum content 2% by weight), and 0.05 part of a siloxane modified solution of acetylene alcohol, and mixed uniformly. By mixing, a silicone composition for optical communication fiber was obtained. The viscosity of this composition was approximately 1800 centistokes at 25°C, and the hardness of the cured product was 70 according to JIS-K6301. When the composition of this example was used to coat a silica glass core fiber in the same manner as in Example 1, a coating film with a uniform surface was obtained as a cladding layer. Example 3 100 parts of a linear dimethylpolysiloxane having a viscosity of about 2000 centistokes at 25° C. and having trivinylsiloxy groups at both ends of the molecule were added with the formula [(CH ₃ ) ₃ SiO _0.5 ] _1.1 [(CH ₂ =CH) ₃ SiO0.5] _0.05
[SiO ₂ ] Methylvinylsiloxane copolymer shown as _1.066.7
%, 6.6 parts of methylhydrodienepolysiloxane containing 1.34 mol/100 g of SiH bonds, 0.05 part of an octyl alcohol modified solution of chloroplatinic acid (platinum content 2% by weight), and 0.05 part of a siloxane modified product of acetylene alcohol, and mixed uniformly. The mixture was mixed to obtain a silicone composition for optical communication fiber. The viscosity of this composition was approximately 3000 centistokes at 25°C, and the hardness of the cured product was 75 according to JIS-K6301. Next, a quartz glass core fiber was coated using the composition of this example in the same manner as in Example 1, and a coating film with a uniform surface was obtained.

Claims (1)

[Claims] 1 (A) The following general formula (1) (In the formula, R is a substituted or unsubstituted monovalent hydrocarbon group containing no aliphatic unsaturated group, a is a number of 0 or 1, and n is a positive integer)
100 parts by weight, (B) Contains (CH ₂ = CH) _3-b RbSiO _0.5 unit, R ₃ SiO _0.5 unit and SiO ₂ unit, (CH ₂ = CH) _3-b RbSiO _0.5 unit relative to SiO ₂ unit Organopolysiloxane having a sum of molar ratios of _{0.5 to 0.5} units of R ₃ SiO and 0.5 to 2 and a vinyl group content of 0.5 to 9% by weight (R in the formula of each unit has no aliphatic unsaturated bond) (substituted or unsubstituted monovalent hydrocarbon group, b represents the number 0, 1, or 2) 5 to 150 parts by weight, (C) Organocarbons having two or more hydrogen atoms directly bonded to a silicon atom in one molecule polysiloxane in an amount sufficient to provide 0.7 to 5 hydrogen atoms directly bonded to silicon atoms per vinyl group in components (A) and (B), and (D) containing a catalytic amount of platinum or a platinum compound. 1. A silicone composition for optical communication fiber, which is characterized by: