JPH0695170B2 - UV curable resin coated tape type optical fiber - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to a UV-curable resin-coated tape-type optical fiber. More specifically, the present invention relates to a silica glass tape type optical fiber having a resin coating and excellent in low temperature characteristics.

[Prior Art] A silica glass optical fiber is provided with a multilayer resin coating in order to protect the optical fiber from an external force or impact. These resin coatings are usually provided on the primary coating directly above the optical fiber and on the outside thereof.
It is composed of a secondary coating, and optionally a buffer layer may be provided between the primary coating and the secondary coating.

Further, there is also known a tape-type optical fiber in which such an optical fiber is used as an elemental wire, a plurality of optical fiber elemental wires are arranged in parallel, and these are coated and fixed with a resin.

Optical fibers are used in a variety of environments and have been modified to have the properties required in each environment. For example, when used at a low temperature (-10 ° C or less) such as in a severe cold region, the optical transmission loss becomes large. It is believed that this phenomenon is because microbending occurs in the optical fiber due to shrinkage of the resin coating,
As the primary coating, a soft resin having a Young's modulus of 1 to 100 kg / cm ^{2 at} room temperature and having a Young's modulus which hardly changes even at a low temperature (about -30 ° C) is used.

[Problems to be Solved by the Invention] However, even if a resin having a small Young's modulus even at a low temperature is used as a primary coating agent, an increase in optical transmission loss of an optical fiber at a low temperature still exists. This phenomenon is also observed in the tape type optical fiber.

The inventors of the present invention have found that even if the resin whose Young's modulus increases at a low temperature has a specific Young's modulus, most of the Young's modulus changes, not to mention the above-mentioned significant increase in optical transmission loss. The present inventors have completed the present invention by discovering the astounding fact that the increase in loss at a low temperature is smaller than that of a non-less one.

[Means for Solving Problems] That is, according to the present invention, a plurality of silica glass optical fiber strands having a primary coating and a secondary coating made of an ultraviolet curable material of an ultraviolet curable resin are fixed with a resin. A tape type optical fiber whose primary coating of UV cured material is 10 to 100 kg / cm ² and 100 to 20,000 at 25 ° C and -30 ° C, respectively.
kg / cm has a Young's modulus of ^2, and UV cured secondary coating 25 ° C. and -30 respectively ℃ 10~20,000kg / cm ² and
The present invention relates to an ultraviolet curable resin-coated tape type optical fiber having a Young's modulus of 10 to 60,000 kg / cm ² .

[Operations and Examples] A major feature of the resin-coated tape-type optical fiber of the present invention is that the resin whose Young's modulus increases at low temperature, which is conventionally considered to increase the optical transmission loss at low temperature, is used as the secondary resin. An ultraviolet curable resin can be used as the coating resin.

It is not clear why the increase of the optical transmission loss is reduced by using the ultraviolet curable resin having the temperature dependence of the specific Young's modulus as the primary and secondary coatings, but as shown in the examples described later, Excellent effect can be obtained.

The optical fiber targeted by the present invention may have any structure or module as long as it is a silica glass tape type optical fiber.

As described above, the UV curable resin used for forming the primary coating, which is an important feature of the present invention, is a UV curable product.
10 to 100 kg / cm ^{2 at} 25 ° C, preferably 30 to 80 kg / c
m ² , particularly preferably having a Young's modulus of 50 to 80 kg / cm ² ,
And at a low temperature of -30 ℃, Young's modulus increased to 100 ~ 20,00.
0 kg / cm ^2, preferably those 500~5,000kg / cm ^2, particularly preferably a 1,000~3,000kg / cm ^2. A material having temperature dependence of Young's modulus in this range is surprisingly superior to the conventional one in light transmission characteristics at low temperatures. Examples of the UV-curable resin for forming the primary coating include urethane acrylate-based, polybutadiene acrylate-based, silicone acrylate-based, polyester acrylate-based, epoxy acrylate-based, and polyether acrylate-based UV-curable resins. Among them, urethane acrylate resins are preferable, and those containing a urethane acrylate oligomer containing at least one polyester polyol unit are particularly preferable. For example, the polyol component is polytetramethylene glycol (PTMG) and a polyester polyol of adipic acid and 1,6-hexanediol, the isocyanate component is isophorone diisocyanate (IPDI), and the acrylate component is 2-hydroxyethyl acrylate (HEA). Those are preferable.

The UV curable resin used to form the secondary coating has a cured product of 10 to 20,000 kg / c at 25 ° C and -30 ° C, respectively.
Any material having m ² and a Young's modulus of 10 to 60,000 kg / cm ² may be used. Specific examples thereof include, for example, urethane acrylate-based, polybutadiene acrylate-based, silicone acrylate-based, polyether acrylate-based, polyester acrylate-based, epoxy acrylate-based, cation-polymerizable epoxy resin, unsaturated polyester, or UV curing of these mixed systems. Resins are mentioned.

In the present invention, a buffer layer may be provided between the primary coating and the secondary coating. As the resin used for forming the buffer layer, an ultraviolet curable resin such as urethane acrylate-based, silicone acrylate-based, polybutadiene acrylate-based, polyether acrylate-based, polyester acrylate-based is preferably used, and the Young's modulus of the cured product is
Suitably, it is 10 to 1,000 kg / cm ² , preferably 10 to 100 kg / cm ² at 25 ° C.

The thickness of the primary coating, buffer layer and secondary coating varies depending on the optical fiber core structure, etc.
m, 0-300 μm and 10-500 μm.

Each UV curable resin is made into a varnish by adding an appropriate reaction diluent, a photopolymerization initiator, a pigment and the like to each resin. Examples of the reaction diluent include HEA, phenoxyethyl acrylate, IPDI, phenyldiethylene glycol acrylate, phenyltriethylene glycol acrylate, lauryl acrylate, pentaerythritol triacrylate, trimethylolpropane triacrylate, hexanediol diacrylate, triethene glycol diacrylate, Examples include neopentyl glycol diacrylate, tetraethylene glycol diacrylate, N-vinylpyrrolidone, 2-ethylhexyl acrylate, and the like. Examples of the photopolymerization initiator include 1-hydroxycyclohexyl phenyl ketone, benzyl dimethyl ketal, benzophenone, diethoxyacetophenone, 2-hydroxy-2-methyl-1-phenylpropen-1-one, Examples thereof include, but are not limited to, isobutyl benzoin ether, isopropyl benzoin ether, and hydroxycyclohexyl phenyl ketone.

Although various methods are adopted as a method for forming the primary coating, for example, an optical fiber obtained by melting and drawing a silica glass optical fiber preform is applied through a varnish for primary coating and then irradiated with ultraviolet rays to be cured, and then the same. The coating and curing of the varnish for the buffer layer and the coating and curing of the varnish for the secondary coating can be mentioned. The coating conditions and curing conditions may be appropriately selected according to the type of resin used, the coating thickness, the linear speed, and the like.

The resin-coated tape type optical fiber of the present invention may have a structure as shown in FIG. 1, for example.

In FIG. 1, (1) is an optical fiber, an optical fiber provided with a primary coating (2) immediately above it, a buffer layer (not shown) if necessary, and then a secondary coating (3). Several strands (4), usually 5 to 10 strands, are bundled and a tape coating layer (5) is provided around them. Examples of the material of the tape coating layer (5) include urethane acrylate type, polyester acrylate type,
An ultraviolet curable resin such as an epoxy acrylate type, a cationic polymerization type epoxy resin, an unsaturated polyester type or a mixture thereof is used.

The Young's modulus of the resin of the tape coating layer is 25 ° C
2,000 to 20,000 kg / cm ² , 2,000 to 60,000 kg at -30 ° C
/ cm ² is preferred.

Next, the resin-coated tape type optical fiber of the present invention will be described based on examples, but the present invention is not limited to these examples.

Example 1 A urethane acrylate UV curable resin composed of a polyol component (PTMG + polyester polyol of adipic acid and 1,6-hexanediol), an isocyanate component (IPDI) and an acrylate component (HEA) (Dainippon Ink and Chemicals, Inc. ) Manufactured by GRANDIC FC706) as the primary coating material, and as the secondary coating material, urethane acrylate consisting of PTMG, tolylene diisocyanate (TDI) and HEA and epoxy acrylate consisting of bisphenol A. epichlorohydrin and acrylic acid. Was used (Desolite 950Y100 manufactured by Nippon Synthetic Rubber Co., Ltd.).

A GI type silica glass optical fiber preform prepared by the VAD method was drawn at a drawing speed of 30 m / min, and was passed through a pot in which the primary coating varnish was stored at the same speed as the obtained optical fiber (diameter 125 μm) 1 The next coating material varnish was applied and then cured through an ultraviolet irradiation device having an effective length of 50 cm (effective irradiation time of 1 second) to form a primary coating having an outer diameter of 200 μm.

Subsequently, a varnish for secondary coating was applied and ultraviolet irradiation (effective irradiation time of 1 second) was performed to form a secondary coating having an outer diameter of 300 μm, and a resin-coated optical fiber element wire was produced.

The Young's modulus of each coating layer was as follows.

Primary coating: at 25 ° C. at ^{75kg / cm 2 -30 ℃ 2,200kg /} cm 2 2 primary coating: Measurement of 8,500kg / cm ² Young's modulus at 4,500kg / cm ² -30 ℃ at 25 ° C., the use varnish It is formed into a film with a thickness of about 150 μm, and it is sufficiently irradiated with ultraviolet light to cure it and has a width of 15
mm tanzaque-shaped sample was prepared, and the tensile modulus at the time of elongation 2.5% when this sample was subjected to a tensile test at a tensile rate of 1 mm / min was taken as the Young's modulus.

Arrange 5 of these optical fiber strands Desolite 950 Y 10
0 was used to cover all at once, and the tape type optical fiber (0.45 mm × 1.6 mm) was prepared by irradiating with ultraviolet rays and curing.

The obtained resin-coated tape-type optical fiber was bundled for about 30 cm, placed in a thermostatic chamber, and measured the transmission loss at a wavelength of 1.30 μm. The transmission loss at 25 ° C was 0.50 dB / km, The transmission loss did not change even when the temperature was lowered to ℃.

Comparative Example 1 Urethane acrylate composed of PTMG, IPDI, and HEA as a primary coating material (Grandic FC708 manufactured by Dainippon Ink and Chemicals, Inc., Young's modulus at 25 ° C and -30 ° C are both 38 kg / cm ² ) Was used to prepare an ultraviolet-curing resin-coated tape-type optical fiber in the same manner as in Example 1, and the transmission loss was measured in the same manner as in Example 1.
50 dB / km, 0.80 dB / km at -30 ° C (loss increase: 0.3
0dB / Km).

Comparative Example 2 Urethane acrylate UV curable resin (Desolite 950 X 065, 25 ° C and -3 manufactured by Desoto Co., Ltd.) as a primary coating material.
Young's modulus at 0 ° C is 25 kg / cm ² and 30,000 kg / cm, respectively
² ) was used to prepare an ultraviolet-curing resin-coated tape-type optical fiber in the same manner as in Example 1, and the transmission loss was measured in the same manner as in Example 1. As a result, 0.50 dB / Km at 25 ° C.,
It was 53 dB / km at -30 ° C (loss increase: 52.5 dB / km).

Example 2 Ethylene glycol adipate with TDI and H as primary coating
Urethane acrylates consisting of EA (Young's modulus at OGF1,25 ° C. and -30 ° C. of Mitsubishi Yuka Fine Co., Ltd., respectively 22 kg / cm ² and 13,000kg / cm ²⁾ except using Example 1 A UV-curable resin-coated tape type optical fiber was produced in the same manner, and the transmission loss was measured in the same manner as in Example 1. The transmission loss was 0.50 dB / Km at 25 ° C and 0.50 dB / Km at -30 ° C. There was no increase.

Example 3 [Advantages of the Invention] According to the present invention, a resin coating having excellent optical transmission characteristics that breaks the conventional wisdom that the optical transmission loss at a low temperature will be large unless the Young's modulus is low even at a low temperature. An optical tape type fiber can be provided.

[Brief description of drawings]

FIG. 1 is a schematic sectional view of an embodiment of the resin-coated tape type optical fiber of the present invention. (Symbols in the drawing) (1): Optical fiber (2): Primary coating (3): Secondary coating (4): Optical fiber element wire (5): Tape coating layer

Claims (2)

[Claims] 1. A tape type optical fiber in which a plurality of silica glass optical fiber strands, each having a primary coating and a secondary coating formed of an ultraviolet curable resin of an ultraviolet curable resin, are fixed with a resin. UV cured product of 25 ℃ and-
Respectively 30 ℃ 10~100kg / cm ² and 100~20,000kg / cm ²
Has a Young's modulus and the secondary coating of UV cured product is 25 ℃
10 to 20,000 kg / cm ² and 10 to 6 at -30 ℃ and
A UV-curable resin-coated tape-type optical fiber having a Young's modulus of 0,000 kg / cm ² . 2. The ultraviolet curable resin for primary coating contains a urethane acrylate oligomer containing at least one polyester polyol unit.
The optical fiber described in paragraph.