JPH0733445B2 - Method for producing thermosetting polymer blend - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention has been proposed as a flame-retardant material with low smoke generation, toxicity and corrosivity, and has attracted public attention. The present invention relates to a method for producing a thermosetting polymer blend suitable as a base polymer for an article.

[Prior Art] All materials conventionally used as insulators and sheaths for electric wires and cables are flammable materials, and in the event of a fire, a highly integrated wiring system for electric wires and cables. There are many cases in which fire spreads due to the transmission of fire, and the demand for flame-retardant electric wires / cables is rapidly increasing. The flame-retardant property has been demanded. There is VTFT (Vertical Tray Combustion Test) of IEEE (Institute of Electrical and Electronics Engineers) standard 383 as a standard of this flame retardance, and it must pass the combustion test of multi-strand laying that simulates the actual laying condition of electric wires and cables. It has become common to employ a flame retardancy as a condition.

The flame retardancy level set by VTFT is quite severe,
Conventionally, as a flame-retardant electrical insulating composition that can satisfy such severe conditions, a material containing a halogen compound or a phosphorus compound has been proposed and used.

However, such a flame-retardant electrical insulating composition is intended to prevent the combustion by generating a large amount of non-flammable halogen-based gas or the like in the event of a fire, thereby shutting off oxygen around the wires and cables. However, although it exhibits sufficient flame retardant properties, the halogen-based gas, etc. generated at that time is often toxic, such as hydrogen chloride, and the visibility is poor because a large amount of smoke containing such toxic gas is generated. There is also a risk of secondary disaster such as hindering evacuation behavior and fire fighting activities in the event of a fire, or the poisonous gas adversely affecting the human body, and further halogen-based gas reacts with moisture in the air, There is a possibility that it will become hydrohalic acid and corrode the switchboard.

For this reason, a flame-retardant electrical insulating composition is proposed in which an inorganic hydroxide such as aluminum hydroxide or magnesium hydroxide is mixed in place of the halogen-based compound or the phosphorus-based compound, and the safety at the time of the fire is emphasized. Have been attracting attention.

The flame-retardant composition in which the above-mentioned inorganic hydroxide is mixed utilizes the endothermic action when the hydroxide releases crystal water at the time of fire as a flame-retardant effect, and has no smoke or toxicity or corrosiveness. Very few. However, these inorganic hydroxides are inferior in flame retardance to the above-mentioned halogen-based or phosphorus-based compounds, and therefore, there is a problem that they must be mixed in a larger amount, and as a result, mechanical properties such as tensile properties and scratch resistance are increased. However, there is a problem that the physical characteristics are significantly reduced.

The object of the present invention is to solve the problems of the prior art as described above, to mix an amount of an inorganic hydroxide capable of exhibiting sufficient flame retardancy, and to significantly improve its mechanical properties. It is intended to provide a method for producing a polymer blend as the obtained base polymer.

[Means for Solving the Problems] The present invention relates to general formulas [I] and [II] capable of addition reaction in the presence of a platinum compound to 100 parts by weight of a silane-grafted polyolefin which is activated by water and can undergo a crosslinking reaction. ] The two-component silicon-containing compound represented by the formula [2] is blended so that the total amount becomes 2 to 60 parts by weight, the silicon-containing compound is heated to accelerate the crosslinking reaction, and then the silane-grafted polyolefin is added in the presence of a catalyst. It is characterized in that the action of water promotes the cross-linking reaction to form a polymer network polymer network structure invading each other.

(R ₁ : CH ₃ , C ₂ H ₅ , C ₆ H ₅ ) (R ₂ : H, CH ₃ , C ₂ H ₅ , C ₆ H ₅ ) Polyethylene, polypropylene, as the polyolefin used for the silane-grafted polyolefin, Polybutene, poly 4-methylpentene-1, ethylene / propylene copolymer (EP rubber, same in Table 1), ethylene / propylene / diene terpolymer, ethylene / ethyl acrylate copolymer (EEA, same in Table 1) ), Ethylene methyl acrylate copolymer, ethylene / methyl methacrylate copolymer, ethylene / ethyl methacrylate copolymer, ethylene / butene copolymer, ethylene / vinyl acetate copolymer, butyl rubber and the like.

The silane coupling agent used for silane grafting has a vinyl group and is vinyltris (βmethoxyethoxy) silane, vinyltriethoxysilane, vinyltrimethoxysilane, γ-methacryloxypropyltrimethoxysilane, vinyltriacetoxysilane. Is mentioned. The silane-grafted polyolefin can be obtained by grafting these onto a polymer by a radical reaction in the presence of peroxide such as dicumyl peroxide.

The silicon-containing compound is represented by the above general formula [I],] II],
A polymer network structure is formed by these addition reactions, and this reaction can be accelerated by heating. In the above, the total amount of the silicon-containing compounds [I] and [II] is set to 2 to 60 parts by weight because the flame retardant effect cannot be exhibited at 2 or less and the tear strength becomes poor at 60 or more parts by weight. Is.

In addition to the polymer blend, antioxidants, lubricants, flame retardants, fillers, reinforcing agents, colorants, etc. can be added.

[Function] When a silane-grafted polyolefin is blended with a silicon compound within the above range, the thermal decomposition temperature of the polyolefin is increased, dripping at the time of combustion is prevented, and not only a large flame retardancy-improving effect is exhibited but also a crosslinking reaction occurs. By doing so, a polymer network structure penetrating into each other is formed, and thereby mechanical strength such as tear strength and tensile strength can be improved.

[Examples] Hereinafter, the present invention will be described with reference to Examples.

The test materials having the composition shown in Examples and Comparative Examples in Table 1 were kneaded for about 10 minutes by a Brabender (rotation speed: about 35 rpm) kept at a temperature of 110 ° C, and then heated for 5 minutes by a press kept at 150 ° C. It was pressed and formed into a sheet with a thickness of 1 mm. By heating at this time, the thermal crosslinking reaction of the silicon compound was performed on the samples of Examples 1 to 4 and Comparative Example 4.

Except for Comparative Example No.3, other samples are lightly coated with a catalyst (eg dibutyltin dilaurate) on the surface of the sheet, then lightly wrapped in aluminum foil, and do not immerse water directly in a suitable container with water on the bottom. In this way, the silane-grafted polyolefin was crosslinked by allowing it to stand at 80 ° C. for 24 hours.

The respective evaluation methods are as follows.

Temperature index: Nichrome wire was wound so that the glass tube could be heated almost the same as the oxygen index measuring machine based on NES715, and the temperature at which the oxygen index became 21 was measured.

Drip: The presence or absence of drip was observed by observing the presence or absence of drip when the sample used for measuring the temperature index was held horizontally and burned by a burner.

Tensile properties: After being left in a thermostatic chamber at 20 ° C. for 1 day, it was punched out with dumbbell No. 3 and measured at a speed of 500 mm / min using a Shopper type tensile tester.

Tear strength: The tear test was performed at a speed of 200 mm / min using a Shopper type tensile tester in accordance with IEC.

Table 1 shows the respective evaluation results.

Example Nos. 1, 2, 4 which are composed of silane-grafted EEA and a silicon compound and have an interpenetrating network structure, and Example No. 3 which uses EP rubber as the silane-grafted polyolefin have good characteristics. I understand. In particular, it can be seen that the effect of improving the flame retardancy by the silicon compound is great. According to the results of thermal analysis, an increase in the temperature of the thermal decomposition of the polyolefin due to the blending of the silicon compound is clearly recognized, and this is considered to be the effect of preventing drip during combustion.

Furthermore, it can be considered that the blended product according to the present invention forms a polymer network structure invading each other, which prevents a decrease in tensile properties and tear strength.

[Effects of the Invention] As described above, according to the blend of the present invention, using the base polymer as the base polymer, the smokeability, the toxicity, and the corrosiveness are extremely small, and the mechanical properties such as tensile properties and tear strength are excellent. It is possible to provide a flammable electrically insulating material and is very useful industrially.

Claims (1)

[Claims] 1. General formulas [I] and [II] capable of addition-reacting in the presence of a platinum compound to 100 parts by weight of a silane-grafted polyolefin which can be activated by water to cause a crosslinking reaction.
The two-component silicon-containing compound represented by the formula (1) is blended in a total amount of 2 to 60 parts by weight, the silicon-containing compound is heated to accelerate the crosslinking reaction, and then the silane-grafted polyolefin is added in the presence of a catalyst. A method for producing a thermosetting polymer blend in which a cross-linking reaction is promoted by the action of water to form a polymer network structure invading each other. _{(R 1: CH 3, C} 2 H 5, C 6 H 5) (R 2: H, CH 3, C 2 H 5, C 6 H 5)