JPH04366903A - Plastic optical fiber - Google Patents

Abstract

PURPOSE:To improve the adhesion between a core and a clad and to lessen an increase in loss by bending and winding without generating a slip, etc., between the core and the clad by constituting a clad material of the cured matter of a two pack mixing type curable silicone resin. CONSTITUTION:The clad layer is constituted of the cured matter of the two pack mixing type curable silicone resin. The elongation of this cured matter is >=40% and the tensile strength is >=0.4kgf/mm<2>. This cured matter is formed by curing, for example, org. polysiloxane having at least two pieces of vinyl groups in one molecule and org. hydrogenated polysilixane in the presence of a slight amt. of platinum or platinum compd. The core material is polycarbonate or polycarbonate copolymer and polyarylate is on the outer side of the clad layer. The two pack mixing type curable silicone resin is 600 to 3500CP in a mixed state and the value of the viscosity when the resin is rested for 8 hours at 25 deg.C is specified to <=2 times the viscosity of the state right after the mixing.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a plastic optical fiber with excellent heat resistance, and more particularly to a high-strength plastic optical fiber with excellent core-cladding adhesion.

0002

2. Description of the Related Art Although plastic optical fibers have a higher transmission loss than quartz glass fibers, they are flexible and do not break, so they are attracting attention as short-distance optical communications equipment for automobiles, consumer electronics, and other devices. However, the core material of most plastic optical fibers is made of polymethyl methacrylate, and the heat resistance temperature is about 80°C. However, heat resistance of about 100° C. is insufficient for use as a signal transmitter in automobiles, etc., and in recent years, research has been actively conducted on improving the heat resistance of plastic optical fibers. On the other hand, optical fibers using polycarbonate resin as the core material are attracting attention as a promising type of heat-resistant plastic optical fiber.

0003

[Problem to be solved by the invention] By the way, the cladding material must be selected depending on the heat resistance of the core material.
When the core material is polycarbonate, fluororesin, fluorinated acrylic resin, etc. are used as the cladding material. However, all of these fluorine-containing resins have poor adhesion to the core material, causing bending and bending of the plastic optical fiber.
There is a drawback that the winding increases transmission loss.

[0004]Also, polymethylpentene is used as a cladding material, but it has a drawback of poor heat resistance because its heat resistance temperature is about the same as that of the core material. An example of using silicone resin as a cladding material has also been proposed (Japanese Unexamined Patent Publication No. 61-245110), but the cladding material may break or peel off due to manual rubbing or grinding, and processing may be difficult. There are some.

[0005]

[Means for Solving the Problems] The present inventors have conducted extensive research to overcome the drawbacks of conventional plastic optical fibers, and as a result, we have developed a cured product of a two-component mixed curable silicone resin for the cladding material. is 40% or more, tensile strength is 0
．． It was discovered that the object could be achieved by using a material with a pressure of 4 kgf/mm2 or more, and based on this knowledge, the present invention was accomplished.

That is, the present invention is characterized in that the cladding layer is made of a cured product of a two-part mixed curable silicone resin, and the cured product has an elongation of 40% or more and a tensile strength of 0.4 kgf/mm2 or more. The company provides plastic optical fibers.

[0007] Formation of the cladding layer in the plastic fiber of the present invention involves coating a core material made of plastic with a silicone resin solution having a viscosity of 600 to 3,500 cp, which is a mixture of two solutions, using a die and curing it. It can be done by In this case, the viscosity of the coating liquid is 600
If it is lower than cp, the two-part mixed curable silicone resin will flow easily from the die during coating, making it difficult to apply it uniformly, and if it exceeds 3,500cp, it will be extremely difficult to coat at high linear speed (uneven coating, (foaming occurs)
It is from.

Furthermore, if the viscosity becomes more than twice the initial value at room temperature (25°C) 8 hours after mixing, it becomes difficult in terms of productivity, and the die etc. must be cooled, and dew etc. processability is significantly reduced. Further, it is preferable that the coating is cured at 150° C. for gelation within 2 seconds. This is because deformation of the core material occurs if the curing time becomes long or if curing is required for a long time at high temperature. However, in view of productivity, a curing temperature of at least about 120° C. is required, so a polycarbonate resin having a higher heat resistance is preferably used as the core material.

The elongation of the cured two-component silicone resin used in the cladding material of the present invention is 40% or more, and the tensile strength is 0.
．． Must be 4kgf/mm2 or higher. This is because if the elongation is less than 40%, the fiber will easily break when stretched by hand or when the core material or fiber expands or contracts at high temperatures. Also, the tensile strength is 0.4
If it is smaller than kgf/mm2, it not only exacerbates the above-mentioned drawbacks, but also becomes extremely brittle, causing the problem that the cladding material can be peeled off by simple rubbing.

The silicone resin used as the cladding material of the present invention has a strength of 0.4 kgf/mm 2 or more, but it is preferable to provide a protective layer to further increase the strength. The protective layer must have heat resistance of 150°C or higher, but it must be selected from a material that can be coated and molded at 340°C or lower. This is because the core material is deformed by the heat. In addition, a material with a higher refractive index than the cladding material must be selected because light propagates within the cladding. Considering weather resistance, etc., polyarylate (wholly aromatic polyester) polymers (including copolymers) are optimal for such resins.

The silicone resin forming the cladding material of the present invention is a cured product of a two-component mixture type curable silicone resin, which includes, for example, (i) an organic polysiloxane having at least two vinyl groups in one molecule; and (ii) an organic hydrogenated polysiloxane can be formed by curing them in the presence of a trace amount of platinum or a platinum compound.

Examples of the organic polysiloxane (i) include those represented by the following general formula (I), and (ii)
) Examples of the organic hydrogenated polysiloxane include those represented by the following general formula (II).

General formula (I)

[Formula 1] (wherein, R1 to R4 represent a lower alkyl group or an aryl group, and may be the same or different from each other, R5
and R6 represents an alkenyl group. m represents an integer. )

General formula (II)

[Formula 2] (In the formula, R7 to R11 represent a lower alkyl group or an aryl group, and n and p represent integers.)

[0015] General formula (I) and general formula (II) will be explained in detail. Examples of the alkyl group for R1 to R4 include methyl, ethyl, propyl, butyl, and the like. Examples of the alkenyl groups for R5 and R6 include alkenyl groups such as vinyl, allyl, 1-propenyl, isopropenyl, butenyl, pentenyl, hexenyl, heptenyl, octenyl, and undecenyl, with vinyl groups being particularly preferred. Further, in the organic polysiloxane (i), an example has been shown in which alkenyl groups are bonded to both ends, but the alkenyl group is not limited to this, and may be bonded to a side chain.

[0016] The aryl group represented by R1 to R4 is preferably a phenyl group. Further, examples of the alkyl group of R7 to R11 include methyl, ethyl, propyl, etc., and examples of the aryl group include a phenyl group.

This organic polysiloxane of (i) above and (
The mixture of ii) with the organic hydrogenated polysiloxane is cured in the presence of a predetermined amount of platinum or a platinum compound,
This polymerization itself using a platinum catalyst can be carried out according to a conventional method. The amount of platinum catalyst is preferably 0.05 ppm or more, but the amount is not particularly limited. The curing time is determined by the amount of platinum. A platinum catalyst is usually added to the liquid side of general formula (II).

[0018] In the cladding method, the spun core material is passed through a die by a conventional method, and the defoamed two-component mixed silicone resin placed in the die is uniformly applied.
It is thermally hardened in a heating furnace installed below it. The fiber is further wound at a constant speed by a winder installed below.

In the plastic optical fiber of the present invention, for example, by introducing a phenyl group into at least a portion of R1 to R11 of the compound represented by the general formula (I) or (II) used, the refractive index can be adjusted to 1.40. ~1.5
It is possible to change it up to about 4. The refractive index is 1.
A value of about 40 to 1.50, preferably 1.40 to 1.47 is good. This is because if the refractive index is too large, crystallization will occur and the transmittance will decrease. Further, the strength or elongation is adjusted by the length of the -SiO- chain of each liquid.

[0020]

EXAMPLES Next, the present invention will be explained in more detail based on examples.

Example 1 Polycarbonate Panlite L-12 as core material
50 (trade name, manufactured by Teijin Kasei Co., Ltd.), it was supplied to a spinning device under an inert gas, and spun from a head at 270°C. After the spinning has entered a steady state, a split die is placed in the middle using a conventional method (a) A two-component mixed silicone resin having physical properties as shown in Table 1 is placed in the die and applied as a cladding layer, and (b) Curing was performed by heating in a heating furnace.

[0022] The temperature of the heating furnace is 420°C, and the length is 100cm.
It was m. The spinning speed was 10 m/min. The core diameter is 0.98mm and the cladding thickness is 0.08m.
It was m. Loss value of the obtained plastic optical fiber, core (polycarbonate only) loss value (770 nm
5mm-1mm cut pack), the increase in loss when wrapped 10 times around a rod with a diameter of 20mm, the elongation of the plastic optical fiber when pulled, the elongation of the cladding material, and the situation when the fiber was rubbed by hand were observed. (Table 2).

[0023] Also, polyarylate U-20 is applied to the outside of this layer.
30 (manufactured by Unitika). The extrusion temperature was 310°C at the head temperature. Loss value of the obtained plastic optical fiber (5mm-1mm cut pack = 770nm
), and the increase in loss when wrapped 10 times around a rod with a diameter of 20 mm,
The elongation of the plastic optical fiber (100 mm/min, 100 mm between chucks) and the increase in loss after 10 days at 125° C. were measured (Table 3). Situation when rubbing again (by hand), 20
% when pulled (100mm/min, chuck distance 100mm
) was measured and shown in Table 3.

[0024]

[Table 1]

[0025]

[Table 2]

[0026]

[Table 3]

Examples 2 to 4, Comparative Examples 1 to 2 Polycarbonate Panlite L-1250 was used as the core material,
A plastic optical fiber was prepared as in Example 1 using a silicone resin having the physical properties shown in Table 4 below as the cladding material, and the physical properties were evaluated in the same manner as in Example 1. This is shown in Tables 5 and 6.

[0028]

[Table 4]

[0029]

[Table 5]

[0030]

[Table 6]

Comparative Example 3 Polycarbonate L-1250 as a core material and ethylene-tetrafluoroethylene copolymer Tefzel 200 (trade name, manufactured by DuPont) as a cladding material were introduced into a double spinning device under an inert gas, and heated at 280°C. A plastic optical fiber was obtained by double spinning using a double spinneret set at . The core diameter was 0.95 mm, and the cladding thickness was 0.05 mm. The loss value of the obtained plastic optical fiber was 1.
When the fiber was wound 10 times at 2 dB/m and a diameter of 20 mm, the loss increase was 1.24 dB and the fiber elongation was 120%.

Example 5 Polycarbonate Panlite L-12 as core material
A plastic optical fiber was prepared in the same manner as in Example 1 using a silicone resin having physical properties as shown in Table 1 as the cladding material.

Next, coating was performed using ethylene-tetrafluoroethylene copolymer Tefzel 200 as a protective layer. The loss value was 1.12 dB/m, and the loss increase when the wire was wound 10 times to a diameter of 20 mm was 0.70. Also,
The increase in loss when stretched by 20% was 0.11 dB/m. The loss increase after 10 days at 125°C was 0.21 dB/m.

[0034]

Effects of the Invention The cured product of the two-component mixed silicone resin has a heat resistance temperature of 150°C or higher, and can maintain a heat resistance temperature of 150°C or higher as a cladding material for a fiber. It is also possible to coat the core material at room temperature, and it can be coated at 150℃.
Unlike thermoplastic resins that have the above-mentioned heat resistance, the core material can be coated without being exposed to heat, so there is no increase in loss during coating. Furthermore, since the core material is coated in a liquid state at room temperature and then cured, the adhesion between the core and cladding is extremely good, and since it is rubber-like,
There is no slippage between the core and the cladding, and the increase in loss due to bending and winding is small.

[0035] The tensile strength of silicone rubber is 0.4 kgf.
/mm2 or more, which is stronger than ordinary thermosetting silicone, and there is no problem with its strength as a fiber cladding material. However, since it has an elongation of 40% or more, even when the core material expands and contracts at high temperatures, or when it is stretched at room temperature, the core-cladding does not peel or break. Furthermore, when polyarylate is used as the protective layer, the strength increases dramatically, and this is noticeable against lateral pressure. It also has the function of suppressing fiber shrinkage at high temperatures.

Claims (3)

[Claims] Claim 1: The cladding material is made of a cured product of a two-part mixed type curable silicone resin, and the elongation of the cured product is 4.
0% or more, and has a tensile strength of 0.4 kgf/mm2 or more. 2. Claim 1, wherein the core material is polycarbonate or a polycarbonate copolymer, and the outside of the cladding layer is coated with polyarylate.
Plastic optical fiber described. 3. The two-component mixed curable silicone resin has a mixed state of 600 to 3,500 cp, and when left at 25° C. for 8 hours, the viscosity is 2 of that of the state immediately after mixing.
2. The plastic optical fiber according to claim 1, wherein the plastic optical fiber is less than or equal to twice as large.