JPS6140524Y2 - - Google Patents

Description

[Detailed explanation of the idea]

The present invention relates to a protective cover used to protect objects from flames, and more particularly to a protective cover suitable for protecting objects that are exposed at high places, such as overhead communication cables. The cover that protects the object that is exposed at a high place is required to satisfy the following various characteristics. To protect an object from flames without dripping melt even if it is scorched by flames from below. To maintain the protective function in the event of a fire even if exposed to sunlight or rainwater for a long time. It must have excellent moldability to enable mass production. Among the above requirements, some are particularly demanding. The reason is that when an existing object is covered with a protective cover, the object usually has unevenness, so some parts of the inner surface of the protective cover will come into contact with the surface of the material, and some parts will remain out of contact. . If the protective cover is heated to a high temperature with a flame under such conditions, even if its constituent material is a thermosetting resin, many thermosetting resins will depolymerize, break crosslinks, etc. This is because it becomes molecularized and easily melts and drips, particularly from the non-contact portions. Needless to say, if a hole is created in the cover due to dripping, the cover will deteriorate or lose its protective function. In view of the above, the present invention proposes a new protective cover that satisfies the above requirements, which comprises a base polymer containing an ethylene-vinyl acetate copolymer component and a vinyl chloride component, and a base polymer containing an ethylene-vinyl acetate copolymer component and a vinyl chloride component, and , consisting of 5 to 70 parts by weight of an organic blowing agent and 3 to 50 parts by weight of zinc or a zinc compound in terms of zinc amount, and is reinforced with a heat-resistant reinforcing material. . As the base polymer, a graft polymer of ethylene-vinyl acetate copolymer and vinyl chloride, a mixture of ethylene-vinyl acetate copolymer and polyvinyl chloride and/or the above graft polymer, etc. are used. The content of the vinyl acetate component in the base polymer is preferably about 20 to 50% by weight, while the content of the vinyl chloride component is preferably about 40 to 70% by weight. As the organic foaming agent, one that can decompose at a temperature of 100 to 400°C and release nitrogen gas, carbon monoxide, carbon dioxide gas, ammonia gas, etc. to foam the organic polymers is used. For example, organic amines such as melamine, urea formaldehyde, aminoacetic acid, trimethylolmelamine, hexamethylolmelamine, melamine resin, N,N'-dinitrosopentamethylenetetramine, guanidine, dicyandiamide, butylurea, polyamide resin, azodicarbonamide, Examples include organic amides such as nitrososulfonamide, and sulfonylcarbazides such as p-toluenesulfonyl semicarbazide and p,p'-oxybenzenesulfonylcarbazide. Zinc or zinc compounds include zinc powder,
3ZnO・2B ₂ O ₂・3H ₂ O, 2ZnO・3B ₂ O ₂・31/2H ₂ O
Zinc borate compounds such as ZnO・ZnMoO ₄ ,
These include molybdenum/zinc compounds such as CaO/ZnMoO ₄ , ZnO, ZnCO ₃ , Zn ₃ (PO ₄ ) ₃ /4H ₂ O, etc. When the Kaba of the present invention is heated with a flame, a dehydrochloric acid reaction occurs in the base polymer due to the action of the generated zinc oxide, and the base polymer is carbonized. It forms an insulating carbonized foam layer that protects objects from flames. Therefore, the zinc compound is not limited to the above-mentioned examples, but any compound that decomposes at high temperatures during a fire to produce zinc oxide can be suitably used. If the amount of organic blowing agent, zinc or zinc compound used is small, the foamed carbonized layer formation effect will be poor, while if the amount used is excessive, the moldability of the composition will be poor, so the amount of these components used is The organic blowing agent is preferably about 5 to 70 parts, and the zinc or zinc compound is preferably about 3 to 50 parts in terms of zinc amount, per 100 parts (by weight, hereinafter the same) of the base polymer. In addition, from the viewpoint of improving molding processability, the organic blowing agent, zinc or zinc compound should be used as finely powdered as possible.
Particularly preferred is one that passes through a 300 mesh sieve. If necessary, the polymer composition consisting of the above-mentioned components may contain ordinary compounding agents for rubber and plastics, such as ordinary flame retardants, anti-aging agents, plasticizer fillers, etc., in ordinary amounts. . In particular, the use of flame retardants is preferred, for example inorganic flame retardants such as antimony trioxide, hydrated alumina, ammonium polyphosphate, tetrabromobisphenol, decabromodiphenyl oxide, perchloropentacyclodecane, tris, bromochloropropyl. Examples include organic flame retardants such as phosphates. As heat-resistant reinforcing materials, fibers of inorganic materials such as glass, asbestos, carbon, ceramics, various metals, wool, woven fabrics, non-woven fabrics, etc. are used, and heat-resistant reinforcing materials such as phenolic resin, polyimide, polytetrafluoroethylene, etc. Organic resin fibers (for example, Kynol: trade name), woven fabrics, non-woven fabrics, etc. are used. When using fiber as a heat-resistant reinforcing material, the so-called
In the same way as for FRP, for example, length 3 to 15
About 5 to 100 parts of short fibers of mm in diameter are mixed with 100 parts of the above-mentioned polymer composition and formed into a desired cover shape. In addition, when using a woven fabric or a non-woven fabric, for example, the above-mentioned polymer composition is applied to one side, both sides, or an intermediate layer of one or multiple layers of a woven fabric or non-woven fabric with a thickness of 0.1 to 1.0 mm, or a layer of the composition is applied. It may be used by embedding a layer of woven fabric or non-woven fabric therein. When wool is used, it may be compressed to form a nonwoven fabric and used in the same manner as a nonwoven fabric, and those that can be mixed with a polymer may be used by mixing with the above polymer composition. Further, as a heat-resistant reinforcing material, a mesh body made of metal wires of steel, mild steel, stainless steel, aluminum, copper, brass, etc. may be used. Such a net-like body has an outer diameter
It is made of metal wire of about 0.1 to 1.0 mm, and the mesh size is about 5 to 100 meshes. Due to the presence of such a heat-resistant reinforcing material, the cover of the present invention has excellent shape retention and mechanical properties under normal conditions, and in the event of a fire, in addition to the rapid foaming fireproofing performance of the polymer composition itself used in the present invention. The supporting action of the foamed carbide layer by the heat-resistant reinforcing material prevents local porosity. Note that the heat-resistant reinforcing material may be used in the form of a sheet, a foil, or a perforated sheet or foil in the same manner as in the case of using a woven fabric or a nonwoven fabric as described above. The thickness of this invention is
For example, it is about 0.5 to 10 mm and can be used as a simple sheet to cover items that require protection, or as a half-split tube or pipe as shown in the following example. Good too. Hereinafter, the present invention will be explained in more detail with reference to Examples and Comparative Examples. The attached figure shows a cross-sectional view of an example in which the half-split protective cover according to the embodiment of the present invention is applied to an overhead-wired communication cable. The split members are connected by bolts and nuts 2. 3 and 4 are a communication cable and messenger wire, respectively, and 5 is a hanger. Cover 1 was constructed from the materials shown in the table below, and the characteristics of each component composition and the protective properties of Cover were evaluated and shown in the same manner.

[Table] Characteristic evaluation (1) Processability of polymer composition The compositions shown in Examples and Comparative Examples were kneaded using two experimental rolls to prepare a compound. Next, a stainless wire mesh (0.48 mm diameter, 10 meshes) and the compound are laminated to form a 4 mm thick molded sheet. Based on the appearance after molding, a molded product that is extremely smooth and uniform is determined to be acceptable, and a molded product that has poor flow and unevenness on the surface and is molded unevenly is determined to be unacceptable. (2) Weather resistance of polymer composition The compound kneaded in (1) was made into a press-molded sheet with a thickness of 2 mm, and a width of 20 mm and a length of 100 mm.
Cut it into strips and wrap it around a mandrel with an outer diameter of 30 mm to make a test piece. This is exposed to a weather meter according to JIS A 1415 for 1000 hours, and the presence or absence of cracks is observed. Those with cracks are judged as unacceptable, and those with no cracks are judged as acceptable. (3) Fire resistance test of heat-resistant cover The samples in the table were tested on the protected cable [conductor diameter 0.65,
100 pairs rubber sheet (0.5mm thick), LAP tape, polyethylene insulation coating (0.3mm thick), outer diameter 40
2 mm long-distance PEF-LAP cable] and messenger wire, and put this into a fireproof test furnace and heat it according to the JIS A 1301 outdoor class 2 heating curve. The short-circuiting time of each wire core during 30 minutes of heating and the unshorted wire core after 30 minutes were expressed as a percentage. If only the untreated cable was used, short circuits would start in 8 minutes, and all wire cores would short circuit in 14 minutes and 20 seconds.

[Brief explanation of the drawing]

The attached figure is a cross-sectional view of an example in which the half-split type protective cover according to the embodiment of the present invention is applied to an overhead wired communication cable. The half members are connected by bolts and nuts 2. 3 and 4 are a communication cable and messenger wire, respectively, and 5 is a hanger.

Claims (1)

[Scope of utility model registration request] A base polymer containing an ethylene-vinyl acetate copolymer component and a vinyl chloride component, and the polymer 100
Protection characterized by comprising 5 to 70 parts by weight of an organic blowing agent and 3 to 50 parts by weight of zinc or a zinc compound per part by weight, and reinforced with a heat-resistant reinforcing material. Hippo.