JP2838895B2 - Flame retardant plastic optical fiber cord - Google Patents

Description

The present invention relates to a novel flame-retardant plastic optical fiber cord, more specifically, a short-distance optical transmission medium having excellent flame retardancy, such as FA equipment and OA equipment. The present invention relates to a plastic optical fiber cord suitably used for automobiles, home electric appliances and the like.

2. Description of the Related Art In recent years, optical communication technology using an optical fiber as an information transmission path has been rapidly advanced and has already reached the stage of practical use.

This optical fiber is classified into two types, a quartz optical fiber for long-distance communication and a plastic optical fiber for short-distance communication. The latter plastic optical fiber is made of a highly transparent thermoplastic resin such as polystyrene, polymethyl methacrylate, or polycarbonate, and has a concentric shape in which the core has a higher refractive index than the sheath. The light incident from one end is transmitted to the other end while being totally reflected at the interface between the core and the sheath. Such plastic optical fibers are usually coated with polyamides such as 6-nylon and 6,6-nylon, high-density polyethylene, cross-linked polyethylene, polyvinylidene chloride, polyacetal, polypropylene, etc. to impart heat resistance and strength. It is coated with materials and used as an optical fiber cord in FA equipment, OA equipment, automobiles, home appliances, panel wiring, etc.

By the way, in recent years, when plastic products are used for the above-mentioned applications, flame retardant regulations are becoming stricter. Therefore, it is demanded that plastic optical fiber cords used for the above-mentioned applications also have good flame retardancy. ing.

In order to impart flame retardancy to plastic optical fiber cords, a means of using a vinyl chloride resin as a coating material is usually employed, and in some cases, a polyethylene-based resin to which a halogen yarn flame retardant or magnesium hydroxide is added. Resin or the like is used. However, when a vinyl chloride resin is used as the coating material, although the obtained plastic optical fiber cord has good flame retardancy, the transmission loss tends to increase due to the effect of the plasticizer,
This tendency becomes particularly strong under high temperature and high humidity. For this reason, there arises a problem that it is necessary to design the performance of the bare optical fiber of the plastic optical fiber so that the performance is about half of the transmission characteristic of the bare optical fiber.

On the other hand, those using a polyethylene-based resin obtained by adding a conventional flame retardant as a coating material do not always have sufficient flame retardancy, and use a large amount of, for example, magnesium hydroxide to increase the flame retardancy. In addition to the inevitable decrease in the fluidity and mechanical strength of polyethylene resin and the need to increase the molding temperature, encoding has the disadvantage of increasing the transmission loss of plastic optical fibers. I have.

For example, the practical flame retardancy of plastic optical fiber cords is required to pass the VW-1 flame test of UL Standard 1581, but transmission of polyethylene-based cables that do not contain halogens such as chlorine and bromine. Those that pass this test without any loss of properties
Previously unknown.

Under these circumstances, the present invention provides a plastic optical fiber cord having excellent flame retardancy without deteriorating the transmission characteristics inherent in a plastic optical fiber bare wire. It was made for the purpose.

Means for Solving the Problems The inventors of the present invention have conducted intensive studies in order to achieve the above object, and as a result, it has been found that a coating layer in contact with a bare plastic optical fiber having a resin mainly composed of polymethyl methacrylate as a core is difficult to form. Consisting of a polyethylene resin composition containing magnesium hydroxide and red phosphorus as a fuel in a predetermined ratio,
Furthermore, it was found that a material having flame retardancy that passed the VW-1 flame test of UL Standard 1581 was suitable for the purpose, and based on this finding, the present invention was accomplished.

That is, the present invention relates to a method in which a plastic optical fiber whose core is a resin mainly composed of polymethyl methacrylate is surrounded by 40 to 60% by weight of magnesium hydroxide and 0.1% of red phosphorus.
-8% by weight and a melt flow index of 0.
Flame-retardant plastic characterized by being coated with a polyethylene resin composition having a weight of from 05 g / 10 min to 1.0 g / 10 min, and having a flame retardancy that passes the VW-1 flame test of UL 1581 An optical fiber cord is provided.

 Hereinafter, the present invention will be described in detail.

In the optical fiber cord of the present invention, a polyethylene resin composition obtained by adding a combination of magnesium hydroxide and red phosphorus is used as a coating material for coating the periphery of the bare plastic optical fiber. As the polyethylene resin used in the polyethylene resin composition,
For example, low density polyethylene, medium density polyethylene, high density polyethylene, linear low density polyethylene, ethylene-
Vinyl acetate copolymers, ethylene-ethyl acrylate copolymers, copolymers of ethylene and other copolymerizable monomers, and the like, may be used alone or in combination of two or more. May be used.

In the present invention, magnesium hydroxide is added to the polyethylene resin in an amount of 40 to 60% by weight based on the total amount of the composition.
, And 0.1 to 8% by weight of red phosphorus, preferably 1%.
It needs to be added at a rate of ５5% by weight. If the amount of magnesium hydroxide is less than 40% by weight, the effect of imparting flame retardancy will not be sufficiently exhibited, and if it exceeds 60% by weight, the fluidity and mechanical strength of the composition will decrease.

On the other hand, if the added amount of red phosphorus is less than 0.1% by weight, the effect of improving the flame retardancy is not sufficiently exhibited, and if it exceeds 8% by weight, the effect is not improved for the amount, and it is more economical. Disadvantageous.

Thus, by combining magnesium hydroxide and red phosphorus, compared to the case of magnesium hydroxide alone, excellent flame retardancy is imparted, so that the amount of magnesium hydroxide added can be kept low, Fluidity can be obtained and the molding temperature can be lowered.In addition, the transmission loss of the obtained optical fiber cord does not increase much compared to the transmission loss of the bare optical fiber itself, and the optical fiber cord has a long term Even in environmental tests under high temperature and high humidity for a long time, transmission characteristics are hardly adversely affected.

In the polyethylene resin composition, carbon black is blended to impart light resistance and avoid obstacles due to light scattering as in the case of ordinary optical fiber cords. A known halogen-based flame retardant may be added, or a suitable dispersant may be added to uniformly disperse magnesium hydroxide and red phosphorus within a range that does not impair the purpose of the present invention. . And the melt flow index of the polyethylene resin composition is:
According to ASTM D-1238, load 2.16kg, orifice length 8m
m, hole diameter 2.10mmφ, value measured under the condition of temperature 190 ° C is 0.05
g / 10 min to 1.0 g / 10 min, preferably 0.1 g / 10 min to 0.
Must be in the range of 5g / 10min. If the melt flow index is less than 0.05 g / 10 minutes, the molding temperature will be high, resulting in an increase in transmission loss, and 1.0 g / 10 min.
If it exceeds minutes, the mechanical strength is low and it is not practical.

In the plastic optical fiber cord of the present invention,
The periphery of the bare plastic optical fiber is coated with the polyethylene resin composition, and the type of the bare plastic optical fiber may be any resin having a core mainly composed of polymethyl methacrylate, particularly Without limitation, a known plastic optical fiber bare wire can be used.

The plastic optical fiber bare wire usually has an outer diameter
A thickness of about 0.2 to 3.0 mm is used, and the layer thickness of the coating layer made of the polyethylene resin composition is usually 0.2 to 2.0 mm.
Is selected in the range.

The plastic optical fiber cord of the present invention is characterized in that it has flame retardancy that can pass the VW-1 frame test of UL Standard 1581 in terms of practicality.
Even in the case where the thickness is as thin as 0.5 to 0.6 mm, the test passes the test, which is an effect that cannot be expected from the conventional one.

Effect of the Invention According to the present invention, a plastic optical fiber cord having excellent flame retardancy can be obtained without significantly lowering the inherent transmission characteristics of the plastic optical fiber bare wire. This plastic optical fiber cord is suitably used as a short-distance optical transmission medium, for example, in FA equipment, OA equipment, automobiles, home appliances, and the like.

EXAMPLES Next, the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples.

Example 1 55% by weight of magnesium hydroxide, 5% by weight of red phosphorus and 0.5% by weight of carbon black were added to an ethylene-ethyl acrylate copolymer containing 10% by weight of ethyl acrylate units, based on the total amount of the composition, and extruded. Knead and melt flow index 0.2g / 10min (ASTM D-1238,
A polyethylene resin composition having a temperature of 190 ° C. and a load of 2.16 kg) was prepared.

Next, using this polyethylene resin composition as a coating material, a plastic optical fiber bare wire Luminous TB-1000
A plastic optical fiber cord was produced by coating the periphery of [PMMA core wire diameter 1.0 mm, manufactured by Asahi Kasei Kogyo Co., Ltd.] so that the outer diameter became 2.2 mm at a molding temperature of 160 ° C.

The optical fiber cord thus obtained had a transmission loss of 140 dB / km, compared to that of the bare optical fiber used, which was 125 dB / km. It was of performance. When the optical fiber cord was left under an environment of a temperature of 85 ° C. and a humidity of 95% for 1000 hours, the transmission loss was 180 dB / km, which was a stable value. The transmission loss was 0.15 radians at the entrance aperture angle,
The measurement was performed at a wavelength of 650 nm by the cutback method of 52 m and 2 m.

When the flame retardancy test of the plastic optical fiber cord was performed according to the VW-1 frame test of UL Standard 1581, all of the tests on 10 samples passed without any danger.

Example 2 In Example 1, Luminous TB was used as the bare optical fiber.
A plastic optical fiber cord was produced in the same manner as in Example 1, except that -500 [made by Asahi Kasei Kogyo Co., Ltd., PMMA core wire diameter 0.5 mm] was used, and the cord outer diameter was 1.5 mm. The flame retardancy test of the optical fiber cord was carried out according to UL Standard 1581.
When performed according to the VW-1 flame test, all of the tests on 10 samples passed without any danger.

Further, a tensile test was performed on the optical fiber cord.
The coating broke when the cord elongation rate was 125% under the conditions of a distance between the chucks of 100 mm and a tensile speed of 100 mm / min.

As is clear from Examples 1 and 2, when the content of magnesium hydroxide was 55% by weight, even if the thickness of the coating layer was as small as 0.5 to 0.6 mm by using phosphorus together, Shows sufficient flame retardancy and mechanical strength.

Comparative Example An ethylene-ethyl acrylate copolymer containing 10% by weight of ethyl acrylate units was mixed with 60% by weight of magnesium hydroxide and carbon black based on the total amount of the composition.
Add 0.5 wt%, extrude and knead, melt flow index 0.02 g / 10 min (ASTM D-1238, temperature 190 ° C, load
2.16 kg) of a polyethylene resin composition was prepared.

Next, using this polyethylene resin composition as a coating material, a plastic optical bare wire Luminous TB-500 having an outer diameter of 0.5 mm
Was coated at a molding temperature of 180 ° C. so as to have an outer diameter of 1.5 mm to produce a plastic optical fiber cord. In this case, the plastic optical fiber bare wire tends to be stretched due to heat, and thread breakage easily occurs, and it is quite difficult to stably draw the cord.

The transmission loss of this optical fiber cord has increased considerably to 350 dB / km, and its flame retardancy test has been carried out according to UL Standard 1581 VW-
When performed according to the one-frame test, two rejects were found in the test on ten samples.

Further, a tensile test of this optical fiber cord was performed in Example 2.
As a result, it was found that the coating was broken at an elongation of 30% and was brittle.

As is clear from this example, when the content of magnesium hydroxide is 60% by weight, the mechanical strength is remarkably reduced, practicability is lost, and flame retardancy is also insufficient.

Claims (1)

(57) [Claims] 1. A bare plastic optical fiber having a resin mainly composed of polymethyl methacrylate as a core is surrounded by 40 to 60% by weight of magnesium hydroxide and 0.1 to 8% by weight of red phosphorus.
And coated with a polyethylene resin composition having a melt flow index of 0.05 g / 10 min to 1.0 g / 10 min, and having a flame retardancy that passes the UL standard 1581 VW-1 flame test. A flame-retardant plastic optical fiber cord characterized by having: