JPH0210182B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention relates to a fire prevention tape having excellent fire prevention properties. [Prior art and its problems] Many types of electric wires and cables are wired in buildings, tunnels, etc., but when a fire occurs, there are many cases where large amounts of damage are caused, and there is an increasing demand for cable disaster prevention. ing. The function of fire prevention tape for cable disaster prevention is of course the usual flame retardancy, but the fire prevention layer formed by winding the tape does not fall off due to combustion, and it adheres to the cable sheath and solidifies to protect the inside. It is desirable to do so. Also, in the case of OF cables and for use inside manholes, oil resistance under normal conditions is also required. Furthermore, appropriate mechanical strength, flexibility, and adhesiveness are required as characteristics for the tape. To meet these demands, tapes have been proposed that are made from polymers such as chloroprene rubber (CR) and chlorinated polyethylene (CPE) with a high content of flame-retardant inorganic compounds such as hydrated alumina. Currently, unvulcanized compositions lack mechanical strength and flexibility due to the high content of inorganic compounds, and have poor oil resistance, so they are currently subjected to vulcanization. However, when vulcanized, the tape loses its tackiness, so some kind of tackiness must be added, and the flame retardant properties are affected by the tackiness.
Moreover, it has the disadvantage of increasing manufacturing costs. [Means for solving the problems] In view of these points, the present invention proposes a fire prevention tape that can meet the required properties without being vulcanized.As a base polymer, 40 to 65% by weight of chlorinated polyethylene and acrylonitrile butadiene rubber are used. A mixture of hydrated alumina and calcium carbonate (weight ratio 1:2-2:1) for 100 parts by weight of a 60-35% by weight mixture.
It is characterized in that a mixture of 50 to 140 parts by weight and 20 to 70 parts by weight of a borate compound is processed into a tape shape in an unvulcanized state. Although the fire prevention tape of the present invention is unvulcanized, it has excellent oil resistance, and also has good mechanical strength, flexibility, and adhesiveness. To explain each component used in the present invention, the base polymer used is a mixture of CPE and NBR, which is essentially anti-inflammatory, and has the effect of CPE, which has strong green strength, and NBR, which has excellent oil resistance. The reason why the mixing ratio of CPE was set at 40% by weight or more was because if it was less than 40% by weight, the green strength would be weakened and the flame retardancy would be impaired, so NBR was set at 35% by weight or more. This is because sufficient oil resistance cannot be obtained if the content is less than 35% by weight. Hydrated alumina contributes to the flame retardancy of the composition through endothermic release of hydrated water, and calcium carbonate acts with hydrated alumina to reduce the solidification of combustion residue when the composition is burned. It is something to give. Further, the reason why the mixing ratio of both is specified to be 2:1 to 1:2 is because the amount of hydrated alumina increases, and if it deviates from this range, the solidification property of the combustion residue becomes weak. Calcium carbonate also acts as a chlorine scavenger; however, if the amount of calcium carbonate increases beyond this range, too much chlorine, which is effective for flame retardancy, will be scavenged and the flame retardancy of the composition will decrease. The reason why the blending amount of the mixture is 50 parts by weight or more based on 100 parts by weight of the base polymer is because if the blending amount is less than 50 parts by weight, the flame retardancy of the resulting composition and the solidification of combustion residue during combustion will be weak. This is because no substantial effect can be obtained, and the reason why the amount is set at 140 parts by weight or less is that if it exceeds this, the mechanical strength, flexibility, and especially adhesiveness of the composition will be impaired. In addition, borate compounds melt at high temperatures during combustion and have the function of suppressing the formation of cracks in the combustion residue.
The amount is based on 100 parts by weight of the base polymer.
This is because if it is less than 20 parts by weight, the effect will be small, and if it exceeds 70 parts by weight, the effect will be saturated and no further effect will be observed. [Example] Next, examples of the present invention will be shown together with comparative examples. Examples 1 to 5, Comparative Examples 1 to 5 Sheet samples were prepared with the compositions shown in the table below, and various properties were measured. The obtained results are also listed in the same table. The method of the characteristic test is as follows. (1) Tensile strength and elongation Based on JISK6301. (2) Adhesive strength A sample was made with a thickness of 0.7 mm and a width of 25 mm.
Measured using the overlay method of JISZ0237. (3) Oil resistance A sample molded to a thickness of 0.7 mm and a width of 50 mm has an outer diameter of approximately 20 mm.
The test sample was a CV cable with a length of about 300 mm, and the test sample was 40 mm in JISC2320 Class 2 No. 1 insulating oil.
Depends on the presence or absence of abnormalities such as cracks and blisters after soaking for 10 days at ℃. (4) Flame retardancy test Conforms to IPCEA S-61-402. Hold the same test sample as in item (3) vertically, tilt the burner at 20 degrees to the sample, and apply the flame to the tip of the cable. After 10 minutes, remove the burner and check the afterflame time, burnout length, and solidification state of the part of the sample in contact with the flame.

【table】

〔effect〕

As is clear from the above table, the fire prevention tape of the present invention has various excellent properties, and its practical value is extremely large.

Claims (1)

[Claims] 1. Mixture of 40-65% by weight of chlorinated polyethylene and 60-35% by weight of acrylonitrile butadiene rubber
A mixture of 50 to 140 parts by weight of a mixture of hydrated alumina and calcium carbonate (weight ratio 1:2 to 2:1) and 20 to 70 parts by weight of a borate compound per 100 parts by weight is left unvulcanized. A fire prevention tape characterized by being processed into a tape shape.