JPH0125708B2 - - Google Patents

Description

[Detailed description of the invention]

FIELD OF THE INVENTION The present invention relates to flame retardant plastic pipes, and more particularly to:
This invention relates to a flame-retardant plastic tube suitable for use as a conduit for inserting and protecting electric wires and cables. Conventionally, when laying electric wires or plastic, the electric wires or cables are sometimes inserted into conduits for mechanical protection. In particular, it is necessary to protect electric wires and cables at locations where temporary wiring is performed at plant construction sites. Conventionally, metal pipes or ceramic pipes have been used as such electric conduits. However, in recent years, corrugated plastic pipes have come into use because they are flexible, economical, and lightweight. Typical examples include polyethylene pipes and polypropylene pipes. However, these plastic tubes have the disadvantage that they have poor fire resistance and are easily combusted by welding fireworks or other fires, which can easily damage the cable. For this reason, making polyethylene or polypropylene flame-retardant is being considered, but the drawback is that making such plastics themselves flame-retardant reduces mechanical strength and abrasion resistance, and the original characteristics of polyethylene or polypropylene are lost. It was hot. SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems and provide a flame-retardant plastic pipe with excellent fire resistance. The present invention is characterized in that a coating layer is provided on the outside of the plastic tube with a fire-resistant composition mainly consisting of an aqueous emulsion, a halogen compound, an inorganic filler, and flame-retardant fibers, and having an enzyme index of 30 or more. It is. The aqueous emulsion resin that is a component of the fire-resistant composition is polyvinyl acetate emulsion, vinyl acetate-ethylene copolymer emulsion, vinyl acetate-vinyl propionate copolymer emulsion-vinyl acetate-vinyl chloride copolymer emulsion-vinyl acetate - Acrylate copolymer emulsions, acrylic ester polymer emulsions (including self-crosslinking types), etc. are desirable. This water-based emulsion resin is a binder for the coating film that forms the coating layer, but since it is generally flammable, it is preferable to use it at a minimum, and the emulsion resin content should be in the range of 15 to 35% by weight of the total weight of the dry coating film. Are suitable. Examples of halogen compounds include chlorinated paraffin, chlorinated naphthalene, decabromodiphenyl oxide, polybromobisphenyl, bisguwanidine tetrabromophthalate, 1,2,5,
There are 6,9,10-hexabromocyclododecane, tris-β-chloroethyl phosphate, etc., and these may be used in combination, and the appropriate amount is 1.5 to 15% by weight of the total weight of the dry coating film. ing. Combining a halogen compound and an antimony compound, such as antimony trioxide, increases the fireproofing effect, so it is desirable to use antimony trioxide in combination. Inorganic fillers include, for example, calcium carbonate,
Examples include aluminum oxide, aluminum hydroxide, magnesium silicate, aluminum silicate, silica, boric acid salt, phosphate frit, etc. These noncombustible substances form the framework of the fire-resistant composition, and preferably contain 40 to 70% by weight of the total weight of the dry coating film. Examples of flame-retardant fibers include Kynor (product of Nippon Kynor Co., Ltd.), poly-P-phenylene terephthalamide fiber, glass fiber, and asbestos.
The amount added is suitably 0.2 to 5% by weight based on the total weight of the dry coating film. Furthermore, if necessary, various pigments, plasticizers, thickeners, surfactants, bactericides, etc. may be included. The above ingredients are blended to prepare a fire-resistant paint made of a fire-resistant composition, but the oxygen index of the dry paint film should be adjusted to 30 or more, and if the enzyme index is less than 30, a sufficient fire-resistant effect will not be obtained. The material of the plastic tube used in this invention is
High molecular weight is preferred; the higher the molecular weight, the better the heat resistance, the less melting deformation when heated, and the better the mechanical strength. For example, polyethylene has a melt index of 0.3 or less, and polypropylene has a melt flow rate of 5.
The following are desirable. The purpose of corrugating plastic tubing is to improve its flexibility. Embodiments of the present invention will be described below based on the drawings. In the figure, 1 is a coating layer made of a fire-resistant composition, 2 is a corrugated plastic pipe, 3 is a cable,
4 is a ribbon type gas burner. Example 1 A corrugated polyethylene pipe 2 having an outer diameter of 127 mm, a thickness of 2.5 mm, and a corrugation height of 13 mm is prepared using high-density polyethylene having a density of 0.95 and a melt index of 0.04. Next, a fire protection paint with the composition shown in Table 1 (1) (oxygen index of the coating film: 42) is applied to the surface of the pipe 2, and after drying, the thickness is 1
A coating layer 1 of mm is formed. 3 in the center of this tube 2
Insert the cross ^- linked polyethylene insulated vinyl sheath cable 3 with 150 mm core and seal its upper end. This test specimen (length 2400 mm) was placed vertically as shown in the figure and heated with the flame of a ribbon type gas burner 4 for 20 minutes. As a result, the polyethylene in the portion hit by the flame was only melted and deformed, and the internal cable 3 suffered almost no damage. Example 2 A corrugated polypropylene tube having the same shape as above was created using polypropylene with a density of 0.89 and a melt flow rate of 1.0. Next, fire prevention paint with the composition shown in Table 1 (2) (oxygen number in the coating film)
40) is applied to the surface of the tube to form a coating layer with a thickness of 1 mm after drying. A heating test similar to that in Example 1 was conducted using this specimen, and as a result, only the polypropylene tube in the portion hit by the flame was melted and deformed, and the internal cable was hardly damaged. Comparative Example A paint having the composition shown in Table 1 (3) (oxygen index of the paint film: 25) was applied to the surface of the corrugated polyethylene pipe of Example 1 so that the thickness after drying was 1.0 mm, and this test was conducted. As a result of conducting a heating test similar to that in Example 1 using a polyethylene pipe, it was not possible to prevent the spread of fire to the polyethylene pipe and cable.

【table】

[Table] Reference example The results of a heating test similar to Example 1 using a corrugated polyethylene pipe without fire-retardant paint applied were as follows.
The fire spread to the top within 5 minutes, and the internal cables were completely destroyed within 10 minutes. Although the above-mentioned embodiment describes the fireproof treatment of a corrugated plastic pipe, the same effect can be achieved even when applied to a smooth plastic pipe. In addition, the material of the plastic pipe is polyethylene,
The present invention is not limited to polypropylene, and corresponding effects can also be obtained with tubes made of virure, rubber, etc. As explained above, according to the present invention, a practical effect can be exhibited as a low-viscosity plastic pipe with excellent fire resistance without reducing the mechanical strength or wear resistance of the plastic pipe.

[Brief explanation of drawings]

The figure is a longitudinal cross-sectional view of a flame-retardant plastic tube for explaining an embodiment of the present invention. 1: Covering layer, 2: Corrugated plastic tube, 3:
Cable, 4: Ribbon type gas burner.

Claims (1)

[Claims] 1 Aqueous emulsion on the outside of the plastic tube,
1. A flame-retardant plastic pipe comprising a halogen compound, an inorganic filler, and a flame-retardant fiber as main components, and a coating layer made of a fire-resistant composition having an oxygen index of 30 or more.