JPS6272735A - Flame-retardant resin composition - Google Patents

Abstract

PURPOSE:To provide a flame-retardant resin composition composed of a crystalline olefinic resin, a mixture of inorganic filler and a silicone-modified ethylene- propylene rubber, free from the generation of harmful gas nor smoke and having excellent flame-retardancy, mechanical properties, electrical insulation, etc. CONSTITUTION:The objective composition can be produced by compounding (A) 100pts.(wt.) of a crystalline olefin resin, preferably crystalline ethylene-vinyl acetate copolymer and/or crystalline ethylene-vinyl acetate copolymer and/or crystalline ethylene-ethyl acrylate copolymer or a resin containing the same with (B) 50-200pts., preferably 60-150pts. of an inorganic filler mixture composed of 50-100(wt)% hydrated inorganic compound (preferably magnesium hydroxide) and 50-0% other inorganic filler (preferably talc) and (C) 5-300pts., preferably 10-250pts. of a silicone-modified ethylene-propylene rubber which is preferably co-vulcanized before compounding.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Field of Application) The present invention is directed to insulating materials for electrical equipment. The present invention relates to an external combustion resin composition that does not generate harmful gases or smoke and has excellent physical properties such as flame retardancy, mechanical properties, and electrical insulation properties.

(Prior Art) Polyolefins such as polyethylene are used as insulating materials for electrical equipment such as electric wires and cables.

Traditionally, these applications require flame retardancy.

A halogenated polymer such as a chlorinated polyolefin is blended with a polyolefin such as polyethylene or polypropylene, or a halogen compound or a mixture of a halogen compound and expensive antimony trioxide is added as a flame retardant to a polyolefin or a blend of a polyolefin and a halogenated polymer. It has been attempted to impart flame retardancy to polyolefins by blending them with. However, in order to achieve high flame retardancy using these materials, it is necessary to increase the amount of halogenated polymer or halogen compound, and as a result, the resulting resin composition has a low mechanical strength. Low: During molding, halogen gases that are harmful to the human body are generated and molds are corroded by this. It has the disadvantage that it generates harmful gases and a large amount of smoke during combustion, which hinders fire extinguishing efforts in the event of a fire.

In order to improve these drawbacks, it has been proposed to blend polyethylene or polypropylene with hydrated inorganic compounds such as aluminum hydroxide or magnesium hydroxide. According to this, although the generation of harmful gases and smoke during molding and combustion are improved, when trying to obtain the desired flame retardancy,
It is necessary to blend 60% by weight or more of a hydrated inorganic compound,
The flowability during molding, product appearance, mechanical properties such as tensile strength and elongation, impact resistance at low temperatures, electrical insulation properties, etc. deteriorate, causing many problems in practical application and making it difficult to make thin-walled products flame retardant. there were.

In order to improve these drawbacks, attempts have been made to reduce the amount of the hydrated inorganic compound by blending polyolefin G with a hydrated inorganic compound and red phosphorus.

According to this method, the mechanical strength of the resulting resin composition is slightly improved, but the compatibility between red phosphorus and the resin is poor (the appearance of the molded product is poor, the cold resistance is reduced, and it also 1. It has the drawbacks of producing phosphorus-based gases that are harmful to the human body and producing a large amount of smoke.

In order to improve these drawbacks, it has been proposed to highly fill hydrated inorganic compounds into ethylene-vinyl acetate copolymers, or mixtures of ethylene-vinyl acetate copolymers or polyvinyl acetate with polyethylene or polypropylene. It was done. This has relatively good flowability during molding, mechanical strength and elongation, but has the disadvantages of low surface hardness, being susceptible to damage, and poor heat deformation resistance and cold resistance.

It has been proposed to reduce the amount of the hydrated inorganic compound by blending an organopolysiloxane and a hydrated inorganic compound with polyethylene, polypropylene, or ethylene-vinyl acetate copolymer. Although the flowability during molding is improved,
It is expensive because organopolysiloxane is used. There are disadvantages such as poor cold resistance, poor mechanical properties such as tensile strength and heat deformation resistance when polyethylene or polypropylene is used, and low flexibility when using ethylene-vinyl acetate copolymer.

In order to improve these drawbacks, ethylene-vinyl acetate co-merged with polyethylene or polypropylene.

Incorporation of organopolysiloxanes and hydrated inorganic compounds was considered. According to this, there is a good balance between heat deformation resistance, flexibility, mechanical properties, and flame retardancy, but
Poor heat aging resistance. Although the cold resistance is slightly improved, it is still insufficient. Since it uses organopolysiloxane, it has drawbacks such as being expensive.

A flame-retardant polyolefin composition in which magnesium hydroxide is blended with a water-crosslinked silane-grafted polyolefin has also been proposed, but this composition has the drawback of extremely low cold resistance.

(Problems to be Solved by the Invention) The present invention 'improves the various drawbacks of conventional flame-retardant resin compositions, eliminates the generation of harmful gas or smoke during molding or combustion, and improves the composition during molding. Good flowability.

Balance between mechanical properties such as tensile strength and elongation and flame retardancy,
Good flexibility, cold resistance (impact resistance at low temperatures), heat deformation resistance, heat aging resistance, electrical insulation properties, and appearance of molded products.
The objective is to provide an inexpensive flame-retardant resin composition that has high surface hardness for molded products (and can also be used to make thin-walled products flame-retardant).

[Structure of the invention]

(Means for solving problems) The present invention uses 100 parts by weight of a crystalline olefin resin.

50 to 200 parts by weight of an inorganic filler mixture consisting of 50 to 100% by weight of a hydrated inorganic compound and 50 to 0% by weight of an inorganic filler other than the hydrated inorganic compound, and 5 to 300 parts by weight of silicone-modified ethylene-propylene rubber. This is a flame-retardant resin composition characterized by the following.

In the present invention, the crystalline olefin resin includes α-olefin polymers such as low-density polyethylene, medium-density polyethylene, high-density polyethylene, polypropylene, and polybutene-1, or mixtures thereof, and crystalline ethylene-propylene copolymers. Polymer.

Copolymers of different α-olefins, such as crystalline ethylene-butene-1 copolymers, or mixtures thereof.

Crystalline ethylene-acrylic acid copolymer, crystalline ethylene-ethyl acrylate copolymer, crystalline ethylene-vinyl acetate copolymer or partially saponified product thereof.

Copolymers of α-olefins and other monomers, such as polyolefins graft-modified with unsaturated carboxylic acids or their anhydrides, or mixtures thereof.

Alternatively, there are mixtures of these, but from the viewpoint of the balance between flame retardancy and flexibility and cold resistance, crystalline ethylene-ethyl acrylate copolymer and/or crystalline ethylene-vinyl acetate copolymer, or It is preferable to use a material containing these.

In the present invention, the hydrated inorganic compounds include aluminum hydroxide, magnesium hydroxide, hydrated calcium silicate,
Although basic magnesium carbonate, hydrotalite, etc. or a mixture thereof are available, it is preferable to use magnesium hydroxide from the viewpoint of flame retardancy and prevention of foaming during pellet molding. Inorganic fillers other than hydrated inorganic compounds include:
Talc, clay, silica, light calcium carbonate, calcium carbonate, calcium oxide, magnesium oxide, zinc oxide, barium sulfate, zeolite, mica, asbestos,
There are glass fibers, glass peas, etc., or mixtures thereof, but it is preferable to use talc because it hardly impairs the 3N flammability, reduces the decrease in extrusion output, and has good processability. Hydrated inorganic compounds and inorganic fillers other than hydrated inorganic compounds may or may not be surface-treated2.For example, higher fatty acids such as stearic acid, metal soaps such as lead stearate, silane compounds, titanate compounds, etc. You may use one whose surface has been treated with a coupling agent or the like. The hydrated inorganic compound is used in a proportion of 50 to 100% by weight of the total inorganic filler mixture. If the amount of hydrated inorganic compound is less than 50% by weight of the total amount of the inorganic filler mixture, the flame retardance will be low. The inorganic filler mixture is used in an amount of 50 to 200 parts by weight per 100 parts by weight of the crystalline olefin resin.
It is preferable to use 150 parts by weight. If it is less than 50 parts by weight, the flame retardance will be low, and if it is more than 200 parts by weight, the mechanical properties will be poor.

In the present invention, silicone-modified ethylene-propylene rubber is a copolymer of silicone rubber and ethylene-propylene rubber, and ethylene-propylene rubber is a rubber-like ethylene-propylene copolymer or ethylene-propylene-diene ternary. It is a copolymer. Although any silicone-modified ethylene-propylene rubber may be used, it is preferable to use one that has been co-vulcanized in advance, since heat aging resistance is increased without impairing processability even without post-crosslinking. Silicone modified ethylene-propylene rubber is 2
5 to 3 parts per 100 parts by weight of crystalline olefin resin
00 parts by weight is used, but from the balance between heat aging resistance and flame retardance, mechanical properties and processability, 10 to 25 parts by weight is used.
It is preferable to use 0 parts by weight. If it is less than 5 parts by weight, flame retardancy and heat aging resistance will be low, and if it is more than 300 parts by weight, mechanical properties such as tensile strength and elongation and processability will be low.

In the present invention, there are no particular restrictions on the order and method of mixing the crystalline olefin resin, inorganic filler mixture, and silicone-modified ethylene-propylene rubber.
The remainder may be mixed or may be mixed sequentially.

The flame retardant resin composition of the present invention may be used uncrosslinked or after crosslinking. Crosslinking methods include crosslinking using electron beams and chemical crosslinking using peroxides and vulcanizing agents. There is no particular restriction on the timing of crosslinking, but from the viewpoint of efficiency it is preferable to do it after all the materials have been mixed. Crystalline olefin resin 1
When the amount of silicone-modified ethylene-propylene rubber used is 100 to 300 parts by weight, it is recommended to use it after crosslinking from the viewpoint of mechanical properties, especially tensile strength.

The flame retardant resin composition of the present invention may optionally contain dyes, pigments, and antistatic agents within the range that does not impede its effects.

Antifogging agents, higher fatty acids such as stearic acid, hot water agents and dispersants such as metal soaps such as magnesium stearate, coupling agents such as titanate compounds and silane compounds, salicylic acid derivatives, and hensifhenones.

Various additives such as ultraviolet absorbers such as henctriazole type, antioxidants such as phenol type, and copper damage inhibitors, and small amounts of other thermoplastic resins such as organopolysiloxane can be blended.

(Example) The present invention will be explained below with reference to Examples.

Examples 1 to 7 and Comparative Examples 1 to 6 After kneading the resin compositions with the formulations shown in Tables 1-1 and 1-2 for 10 minutes using two rolls, the resulting mixture was made into a sheet using a press machine. Using the sheet, a flame retardancy test, a tensile test, a heat aging test, a cold resistance test, and an electrical property test were conducted. The results are also shown in Tables 1-1 and 1-3. The test conditions, display of results, and specifications were as follows.

(1) Flame retardancy test: JIS K-7201/-! l
-Based on. Displayed as oxygen index.

A score of 30 or higher was considered a pass.

(2) Tensile test: When the crystalline olefin resin contains polypropylene, it is based on JIS K-6758, and when it is only an ethylene polymer, it is based on JIS K-6760. Expressed as tensile strength and elongation. tensile strength 1 kg
/ mm” or more.

An elongation rate of 400% or more was considered a pass.

(3) Heat aging test: Displayed as tensile strength residual rate and elongation rate residual rate after being held at 180°C for one week. Tensile strength residual rate 65%
As mentioned above, the elongation rate remaining rate of 60% or more was considered to be a pass.

(4) Cold resistance test: Based on 857M D-746. Displayed in cold-resistant temperature. A temperature lower than -30°C was considered acceptable.

(5) Electrical property test: Compliant with JIS-6723. Displayed as volume resistivity 1 tow value. A value of 5×10 Ω・1 or more was considered to be a pass.

(Margins below) Table 1-2 Formulation [Top sheet*1 A made of silicone 5EP-1721 U-like bottom margins] Table 1-38 people's section Φπ margins) [Effects of the invention] With the present invention, when molding or burning It does not generate harmful gases or smoke, has good flowability during molding, and has a good balance between mechanical properties such as tensile strength and elongation, and flame retardancy.

Flexibility, cold resistance (impact resistance at low temperatures), heat deformation resistance 5 heat aging resistance, good electrical insulation properties and appearance of molded products, high surface hardness of molded products, and can be used to make thin-walled products flame retardant. and as a covering material for electric wires, cables, etc.

Alternatively, it has become possible to obtain an inexpensive flame-retardant resin composition that is ideal for extruding shapes such as spacers for optical fibers.

Claims (1)

[Scope of Claims] 1. Inorganic filler mixture 50 consisting of 100 parts by weight of a crystalline olefin resin, 50 to 100% by weight of a hydrated inorganic compound, and 50 to 0% by weight of an inorganic filler other than the hydrated inorganic compound.
200 parts by weight, and 5 to 300 parts by weight of silicone-modified ethylene-propylene rubber. 2. The flame-retardant resin according to claim 1, wherein the crystalline olefin resin is a crystalline ethylene-vinyl acetate copolymer and/or a crystalline ethylene-ethyl acrylate copolymer, or one containing these. Composition. 3. The flame-retardant resin composition according to claim 1 or 2, wherein the hydrated inorganic compound is magnesium hydroxide.