JPH103011A - Plastic clad optical fiber - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an optical fiber with a clad consisting of a resin reduced in transmission loss, having excellent mechanical characteristics and Young's modulus, by using a plastic contg. a polymer of a multifunctional (meth)acrylate compd. contg. the repeating unit of a fluoroethylene group as clad material. SOLUTION: The plastic contg. polymer of the multifunctional (meth)acrylate compd. contg. the repeating unit of fluoroethylene group is used as the clad material. Trifunctional and higher function and more particularly quadrifunctional compds. are preferably used as the multifunctional (meth) acrylate compd. which is the polymn. component of the clad resin in order to enhance the Young's modulus of the polymer. Further, the use of the compd. expressed by the formula is possible. In the formula, (b), (f) denote positive integers; (d) denotes an integer of >=2; (a), (c), (e), (g), (h), (i) denote 0 or positive integers; X denotes hydrogen or methyl group and Y denotes hydrogen or fluorine.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a plastic clad optical fiber.

[0002]

2. Description of the Related Art A so-called plastic clad optical fiber (PCF) in which a core material is made of quartz, silica or glass and a clad material is made of plastic is relatively inexpensive, has excellent transparency, and has a high numerical aperture. Therefore, it is mainly used as an optical fiber or a light guide for medium and short distance transmission of 1 km or less. Conventionally, a silicone resin (for example, polydimethylsiloxane, polymethylphenylsiloxane, etc.) has been used as the cladding material. However, the silicone resin is generally soft, and when the operating temperature is high, the joining strength of the joint portion with the connector is reduced. Therefore, it cannot be said that the silicone resin can be used in a wide use environment. For this reason, recently high-grade fluororesins have been used.
For example, JP-A-5-9043 discloses an optical fiber using a cured product of an active energy ray-curable compound mainly composed of fluorinated acrylate as a cladding resin for optical fibers.

[0003]

However, if the number of carbon-hydrogen bonds in the cladding resin is large, there is a problem that the transmission loss of the optical fiber is reduced. In order to solve this, a resin containing a large amount of fluorine has been used. However, when the content of fluorine is large, there is a problem that the Young's modulus of the resin is reduced, so that it is difficult to attach a connector to the fiber. Therefore, it has been extremely difficult to satisfy the conflicting demands of reducing the transmission loss by increasing the fluorine content and increasing the Young's modulus. An object of the present invention is to provide a plastic clad optical fiber having excellent transmission loss and mechanical properties, particularly a resin having a high Young's modulus, in view of the above problems.

[0004]

According to the present invention, the cladding resin has a small decrease in Young's modulus even if the content of fluorine is large and the number of carbon-hydrogen bonds is small. Multifunctional (meta) over functional
An object of the present invention is to provide a plastic optical fiber having a resin containing a polymer of an acrylate compound as a cladding.
That is, as described above, even if the content of carbon-hydrogen bonds in the clad resin is reduced, if a resin obtained by polymerizing a specific monomer is used, the transmission loss can be reduced without lowering the Young's modulus. It was made based on the knowledge that it can be done.

Although the reason for this is not necessarily clear, the repeating unit of the fluoroethylene group contained in the polyfunctional (meth) acrylate compound is a linear portion, and the carbon-hydrogen bond content of this portion in the polymer chain trunk is low. It is considered that transmission loss of the optical fiber is greatly affected, and the remaining functional group forms a three-dimensional molecular structure and plays a role in preventing a decrease in Young's modulus. Here, the carbon-hydrogen bond content refers to the ratio of hydrogen atoms to the total number of hydrogen, deuterium, and halogen atoms bonded to carbon atoms.

The plastic-clad optical fiber of the present invention is obtained by coating the above-mentioned monomer on a core such as quartz or glass, and then polymerizing it by irradiating ultraviolet rays or applying thermal energy to form a clad material. To form a resin.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the contents of the present invention will be described in more detail. In the present invention, it is preferable to use a trifunctional or more functional compound, particularly a tetrafunctional compound, as the polyfunctional (meth) acrylate compound to be a polymerization component of the clad resin because the Young's modulus of the polymer can be increased. Further, a compound represented by the following general formula can be used.

[0008]

Embedded image (B and f are positive integers, d is an integer of 2 or more, a, c, e,
g, h, and i are 0 or a positive integer, X is hydrogen or a methyl group, and Y is hydrogen or fluorine.

The polyfunctional (meth) acrylate compound used in the present invention also has a role as a reactive diluent which can adjust the viscosity of the composition before polymerization.
In the above general formula (1), when the number d of the repeating units of the fluoroethylene group is 4 or more, particularly 8 or more, the linear portion in the trunk of the polymer chain becomes longer and the transmission loss is further reduced, which is preferable. Specifically, the following compounds can be used.

[0010]

Embedded image

(CH ₂ ＣＨCHCOO) ₂ CH (CF ₂ ) ₈ CH (OOCCH ＝ CH ₂ ) ₂ (3) (CH ₂ ＣＨCHCOO) ₂ CF (CF ₂ ) ₈ CF (OOCCH ＝ CH ₂ ) ₂ (4 ) (CH ₂ ＣＨCHCOO) ₂ CHCH ₂ (CF ₂ ) ₈ CH ₂ CH (OOCCH ＝ CH ₂ ) ₂ (5)

[0012]

Embedded image

The amount of the polyfunctional (meth) acrylate compound depends on the balance between the Young's modulus of the cladding and the transmission loss.
Moreover, it can be appropriately determined from the viscosity of the composition at the time of coating at the time of production, and is usually 0.1 to 90 parts by weight, preferably 0.1 to 60 parts by weight with respect to 100 parts by weight of the resin composition. And more preferably 1 to 40 parts by weight.

The clad material of the present invention may further contain urethane di (meth) acrylate represented by the following chemical formula.

[0015]

Embedded image

[0016]

Embedded image

[0017]

Embedded image

[0018]

Embedded image

When urethane di (meth) acrylate is contained, the content is usually 5 to 99.9 parts by weight based on 100 parts by weight of the resin composition. If the amount is less than 5 parts by weight, the Young's modulus is low, and if it is more than 99.9 parts by weight, the Young's modulus is high, but the amount of the polyfunctional (meth) acrylate compound containing a repeating unit of a fluoroethylene group is reduced accordingly. Therefore, it becomes difficult to reduce the transmission loss of the optical fiber. In order to satisfy both the Young's modulus and the transmission loss in a well-balanced manner, and to make the viscosity at the time of coating appropriate during production, the amount is preferably 10 to 90 parts by weight, more preferably 15 to 80 parts by weight.

In the present invention, the polymerization initiator is preferably a thermal polymerization initiator or a photopolymerization initiator, and includes the following compounds. As a thermal polymerization initiator, for example,
Examples include di-t-butyl peroxide, t-butyl hydroperoxide, dicumyl peroxide, cumene hydrooperoxide, azobisisobutyl lonitrile. As a photopolymerization initiator, for example, benzyl dimethyl ketal, 1-hydroxycyclohexyl phenyl ketone,
Examples include 2,4, -trimethylbenzoyldiphenylphosphine oxide, fenzophenone, and benzoylmethyl ether. The amount of the polymerization initiator added is
The amount is usually 0.01 to 10 parts by weight, preferably 0.1 to 5 parts by weight, more preferably 0.1 to 3 parts by weight with respect to 00 parts by weight.

[0021]

EXAMPLE 1 30 parts by weight of a compound of the formula (2) as a polyfunctional (meth) acrylate compound, 70 parts by weight of an oligomer of the formula (7) as a urethane di (meth) acrylate, and benzoyl par as a polymerization initiator A polymerizable composition comprising 1 part by weight of the oxide was applied on the circumference of a glass fiber having an outer diameter of 0.2 mm, and polymerized at 100 ° C. for 30 minutes to form a cladding layer having a thickness of 25 μm. When the transmission loss of the produced plastic clad optical fiber was measured, it was 6.0 dB / km at a wavelength of 810 nm. The Young's modulus of the fiber at room temperature was 20 kg / mm ² . Furthermore,
Even when this fiber was attached to a connector and swaged under normal attachment conditions, there was no reduction in transmission loss and no deformation of the fiber was observed.

Example 2 40 parts by weight of a compound of the formula (3) as a polyfunctional (meth) acrylate compound, 60 parts by weight of an oligomer of the formula (8) as a urethane di (meth) acrylate, and benzoyl peroxide as a polymerization initiator One part by weight of the polymerizable composition was applied on the circumference of a glass fiber having an outer diameter of 0.2 mm, and polymerized at 100 ° C. for 30 minutes to form a cladding layer having a thickness of 25 μm. When the transmission loss of the produced plastic clad optical fiber was measured, it was 6.2 dB / km at a wavelength of 810 nm. The Young's modulus of this fiber at room temperature was 22 kg / mm ² . Furthermore,
Even when this fiber was attached to the same connector as the connector used in Example 1 and swaged under the same attachment conditions, there was no reduction in transmission loss and no deformation of the fiber.

Example 3 40 parts by weight of a compound of the formula (4) as a polyfunctional (meth) acrylate compound, 60 parts by weight of an oligomer of the formula (9) as a urethane di (meth) acrylate, and benzoyl peroxide as a polymerization initiator One part by weight of the polymerizable composition was applied on the circumference of a glass fiber having an outer diameter of 0.2 mm, and polymerized at 100 ° C. for 30 minutes to form a cladding layer having a thickness of 25 μm. When the transmission loss of the produced plastic clad optical fiber was measured, it was 6.1 dB / km at a wavelength of 810 nm. The Young's modulus of this fiber at room temperature was 21 kg / mm ² . Furthermore,
Even if this fiber is attached to a connector in the same manner as in Example 1 and swaged under a normal attachment condition, there is no decrease in transmission loss.
There was no deformation of the fiber.

Comparative Example 1 40 parts by weight of pentafluoropropyl acrylate which is a monofunctional acrylate compound, 60 parts by weight of an oligomer of the formula (7) as urethane di (meth) acrylate,
A polymerizable composition comprising 1 part by weight of benzoyl peroxide as a polymerization initiator is applied on the circumference of a glass fiber having an outer diameter of 0.2 mm, and polymerized at 100 ° C. for 30 minutes to form a film having a thickness of 25%.
A μm cladding layer was provided. When the transmission loss of the produced plastic clad optical fiber was measured,
It was 7.5 dB / km at 0 nm. The Young's modulus of the fiber at room temperature was 8 kg / mm ² .
Further, when this fiber was attached to a connector in the same manner as in Example 1 and swaged under normal attachment conditions, the cladding layer was greatly deformed.

Comparative Example 2 30 parts by weight of trifluoromethylpropyl acrylate which is a monofunctional acrylate compound, 70 parts by weight of an oligomer of the formula (8) as urethane di (meth) acrylate, and 1 part by weight of benzoyl peroxide as a polymerization initiator Was coated on the circumference of a glass fiber having an outer diameter of 0.2 mm and polymerized at 100 ° C. for 30 minutes to form a cladding layer having a thickness of 25 μm. When the transmission loss of the produced plastic clad optical fiber was measured, it was 7.0 dB / km at a wavelength of 810 nm. The Young's modulus of the fiber at room temperature was 9 kg / mm ² . Further, when this fiber was attached to a connector in the same manner as in Example 1 and swaged under normal attachment conditions, the cladding layer was greatly deformed.

Comparative Example 3 40 parts by weight of trifluoroethyl methacrylate as a monofunctional methacrylate compound, 60 parts by weight of an oligomer of the formula (9) as urethane di (meth) acrylate, and 1 part by weight of benzoyl peroxide as a polymerization initiator The polymerizable composition comprising the above parts was coated on the circumference of a glass fiber having an outer diameter of 0.2 mm, and polymerized at 100 ° C. for 30 minutes to form a cladding layer having a thickness of 25 μm. When the transmission loss of the produced plastic clad optical fiber was measured, it was 7.5 dB / km at a wavelength of 810 nm. The Young's modulus of the fiber at room temperature was 6 kg / mm ² . Further, when this fiber was attached to a connector in the same manner as in Example 1 and swaged under normal attachment conditions, the cladding layer was greatly deformed.

[0027]

As described above, the present invention provides a carbon-hydrogen bond by using a plastic containing a polymer of a polyfunctional (meth) acrylate compound containing a repeating unit of a fluoroethylene group as a cladding material. Even if the ratio is small, it is possible to provide a plastic-clad optical fiber with a small decrease in Young's modulus and a small transmission loss.

Claims (4)

[Claims] 1. A plastic clad optical fiber, wherein the clad is a plastic containing a polymer of a trifunctional or higher polyfunctional (meth) acrylate compound containing a repeating unit of a fluoroethylene group. 2. The plastic clad optical fiber according to claim 1, wherein the polyfunctional (meth) acrylate compound is tetrafunctional. 3. The plastic clad optical fiber according to claim 1, wherein the polyfunctional (meth) acrylate compound is a compound represented by the following general formula. Embedded image (B and f are positive integers, d is an integer of 2 or more, a, c, e,
g, h, and i are 0 or a positive integer, X is hydrogen or a methyl group, and Y is hydrogen or fluorine. 4. A plastic cladding light wherein the cladding is a plastic containing a polymer of a trifunctional or higher polyfunctional (meth) acrylate compound containing a repeating unit of a fluoroethylene group and a polymer of urethane di (meth) acrylate. fiber.