JPS581741A - Flame-retardant resin composition - Google Patents

Abstract

PURPOSE:To provide the titled compsn. which is non-tacky and suitable for use as a covering material for electric cables and wires, by blending aluminum hydroxide and amorphous silica or carbon black with a resin compsn. consisting mainly of an ethylene/vinyl acetate copolymer. CONSTITUTION:As a base plastic, an ethylene/vinyl acetate copolymer having a vinyl acetate content of 40wt% or higher is used. Two kinds of ethylene/vinyl acetate copolymers are mixed together in such a proportion as to give a vinyl acetate content of 40wt%. The mixture may be used as a base plastic. Alternatively, a mixture obtd. by replacing part of said ethylene/vinyl acetate copolymer or copolymers with a polyolefin such as polyethylene may be used as a base plastic. 120-250pts.wt. aluminum hydroxide and 5-70pts.wt. amorphous silica, carbon black or mixture thereof are blended with 100pts.wt. base plastic to obtain the desired flame-retardant resin compsn.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention is characterized by the use of radiation irradiation or the combination of chemical crosslinking agents.
Let's crosslink! The present invention relates to an excellent flame retardant resin composition that can pass the strict flame retardant test of 0UL758 VW-1 flame retardant test.

In recent years, with consideration given to minimizing damage in the event of a fire occurring in construction, electric wires and cables are also required to meet extremely strict flame retardant standards.

In order to pass the VW-1 flammability test of UL758, which is one of the most stringent standards and is applied to electric wires and cables, the conventional flame-retardant method for glass coating materials for electric wires and cables is as follows. There are many ways.

(1) In the case of vinyl chloride, reduce the flammable lubricant and add antimony trioxide.

01) In case of polyolefin, organic/10g/
Compounds (eg decabromogenyl ether, hexabromobenzene, perchlorointacyclodecane, etc.) and antimony trioxide are added on the order of several tens of PHH.

However, since the coating material made flame-retardant by such means contains a large amount of halogen, it generates a large amount of harmful and harmful gases when burned, so there is a risk of causing another major disaster in the event of a fire. In recent years, a number of other methods have been proposed in which the addition or use of the above-mentioned halogen-containing compounds is eliminated and a hydrous mineralized metal is mixed into the base plastic.

However, in order for K to pass the VW-1 test, which is a strict flammability test mentioned above, by this method, the amount of the water-containing inorganic compound mixed is 2 to 3 times the amount of the base plastic, which is different from the other one. There is a high possibility that the original physical properties of the base polymer will be impaired and the properties as a cable covering material will be lost.

In addition, as shown in JP-A-56-18636, for example, there is also known a method in which the flame retardance can be significantly improved by filling a significantly small amount of a water-containing inorganic compound.

However, the flame retardant resin composition produced by such a method is obtained by extruding it onto a couple, and then folding and stacking the manufactured insulated wire. If the coated wires are rolled up on a pin and pressed against each other, the coating layers will adhere to each other and the separability of the coated wires will inevitably deteriorate.

As a result of intensive studies to solve this problem, the inventors specified the base plastic as described in detail below, and filled it with aluminum hydroxide and amorphous silica or carbon in a specific ratio. They found that the above problem could be solved by doing this and completed this invention.

That is, this invention provides an ethylene-vinyl acetate copolymer having a vinyl acetate concentration of 40 weight or more, or two or more suitable ethylene-vinyl acetate copolymers such that the total vinyl acetate concentration is 40 weight or more. 120 to 250 parts by weight of aluminum hydroxide and amorphous silica or carbon black or A mixture of these 5 to 70
This is a flame-retardant resin composition characterized in that it contains parts by weight.

The reason why the present invention was able to solve the conventional problems as described above could not necessarily be clarified.

8 As already mentioned, the above-mentioned Japanese Patent Application Laid-Open No. 56-18636
While the flame-retardant resin composition disclosed in the publication exhibits high flame retardancy and has excellent physical properties, the inventors' evaluation of the flame-retardant resin composition as a cable covering material On the other hand, very coincidentally, the incorporation of amorphous silica or carbon black used as a rubber reinforcing material in the filler of the present invention surprisingly solves this problem. It is.

This will be clarified by the later examples, but calcium carbonate, clay, which is a common filler for plastics,
In the case of talc, etc., this improvement is hardly recognized, and instead the tensile strength steadily decreases.

Further, the flame-retardant resin composition of the present invention maintains its high non-adhesive properties even when exposed to high temperatures by further crosslinking as appropriate.

The reason for specifying the ethylene-vinyl acetate copolymer used in this invention as described above (in particular, the vinyl acetate concentration is 40- or higher) is that if the MA concentration in the base plastic is not 40- or higher, the base plastic will not work properly. This is because it is impossible to pass VW-1 while maintaining characteristics and flexibility.

Can it be mixed with this ethylene-vinyl acetate copolymer? These include olefin corimer, polyethylene, ethylene-glopylene colimer, and ethylene-d olefin colimer. Further, the amount is desirably less than K 20 PHr in order to maintain mechanical properties.

Next, in the present invention, 120 to 250 parts by weight of aluminum hydroxide is added to 100 parts by weight of the above-mentioned base plastic, but if the amount is below this lower limit, the original purpose of flammability is insufficient. If it exceeds, the excellent mechanical properties and flexibility inherent to the base plastic will be impaired.

Similarly, amorphous silica or Kagen black is 5 to 7.
0 parts by weight is added, but if the amount is below this lower limit, there is no effect of improving the tackiness, and if it exceeds the upper limit, the elongation rate will be 100%.
- Any significant decrease such as reaching below - is not preferable. When these amorphous silicas or carbon blacks are used as a mixture, it is desirable to disperse them sufficiently uniformly in advance using a mixer or the like.

In this invention, any of the known crosslinking methods applied to plastics, such as radiation crosslinking, peroxide crosslinking, and silane crosslinking, can be used as the crosslinking means.

The present invention will be specifically explained below with reference to Examples.

Examples 1-3. Comparative Examples 1 to 6 The composition of Table 1 was coated on a 0.5-conductor, and 10Mra
d electron wrap irradiation (some of the comparative examples were not irradiated) and crosslinked with 0.
A 9- coated cable was obtained.

These cables were evaluated according to the items in the same table, and the results are shown in the same table.

Table 1 However, in the above table, III: Concentrated vinyl acetate [68chi] Pot 2: Calcium carbonate Denbeifun Kako Tohat product name 1113:
Average particle size Is voice, kaolin clay *4: Average particle size 5# ml! I: Amorphous silica, Tokuyama Soda Co., Ltd. product name *6: Aluminum hydroxide, Showa Denko Co., Ltd. product name 1117: Evaluation of insulators according to JIS C3005K *8: Passing all 10 test items is considered gold 19: Cable 1- was wound around a bottle, left to stand at 60°C for 24 hours, and evaluated by unwinding, which was evaluated based on the following criteria.

×... Significant tackiness, Δ... Peeled off but surface damage occurred, ○... No tackiness Examples 4 to 5 Except for replacing a part of the ethylene monoacid vinyl copolymer with polyolefin. The test was carried out in the same manner as in the previous example, and the results are shown in Table 2.

! 1!2 110 4g0.925 M・I-0,5III1
11 Tafmer A4090 Mitsui Petrochemical Co., Ltd. According to the results in Tables 1 and 2 above, Comparative Examples 1 and 3 to 6 all had problems in terms of adhesiveness, and this was due to the lack of amorphous silica or the presence of mixed silica. It depends on K.

Comparative Example 2 does not have this problem, but the amount of the amorphous silica is too large and the elongation is significantly reduced.

On the other hand, in the present invention, such problems have been significantly improved and the characteristics have been balanced, resulting in an overall acceptable product.

As described above, the present invention uses a specific base plastic,
Moreover, by specifying the compositional tendency of the filler, a flame-retardant resin composition was obtained which solved the conventional problems, and the industrial effects such as improved safety were extremely large.

Claims (1)

[Claims] An ethylene-vinyl acetate copolymer having a vinyl acetate concentration of 40 weight or more, or a mixture of two or more suitable ethylene-vinyl acetate copolymers such that the total vinyl acetate concentration is 40 weight or more. How much of these ethylene-vinyl acetate copolymers? 12 parts by weight of aluminum hydroxide per 100 parts by weight of the mixture substituted with lyolefin
A flame-retardant resin composition characterized in that it contains 0 to 250 parts by weight and 5 to 70 parts by weight of amorphous silica, Cargin black, or a mixture thereof.