JP3664431B2 - Heat resistant flame retardant composition - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention does not generate a halogen-based gas or smoke during combustion, has a high degree of flame retardancy and heat resistance, has good mechanical strength, and does not deteriorate molding processability and molding appearance. The present invention relates to a highly filled non-halogen heat-resistant flame retardant composition.
[0002]
[Prior art]
In recent years, from the aspect of safety in the event of fire, non-halogenated flame retardant wires and flame retardant cables, that is, development of wires and cables that generate less smoke and do not generate harmful gases such as hydrogen halide gas, Recently, expectations for such non-halogenation are also increasing from the viewpoint of environmental protection measures including recycling of materials.
For this reason, non-halogen flame retardant compositions based on halogen-free organic polymers have been actively developed, and typical examples include using EVA resins with a high VA content, aluminum hydroxide Known to be flame retardant by adding a large amount of metal hydroxide such as magnesium hydroxide.
However, such a composition is poor in mechanical properties, in particular, tensile strength and tensile elongation, while flame retardancy is improved by using an EVA resin having a high VA content or by adding a large amount of metal oxide. In addition, there is a problem that the extrusion torque is high and the molding process cannot be performed. Further, since the base resin is EVA having low heat resistance, there is a problem that the test piece melts or contracts in the heat resistance test at a high temperature.
With respect to these problems, as described in JP-A-5-144326, the above problems are cleared by irradiating with an electron beam. However, these compositions have the disadvantage that the inorganic material agglomerates and the molded appearance is poor.
[0003]
[Problems to be solved by the invention]
The object of the present invention is a metal having high heat resistance and flame retardancy, sufficiently maintaining mechanical properties, particularly tensile strength and tensile elongation, low extrusion torque, good moldability and good appearance. It is to provide a heat-resistant flame retardant composition with high hydroxide content.
[0004]
[Means for Solving the Problems]
The present invention relates to an ethylene-vinyl acetate copolymer (EVA) 99.5 to 85% by weight having a vinyl acetate (VA) content of 25 to 45% by weight and a polyolefin resin 0.5 to 0.5% modified with an unsaturated carboxylic acid. Heat resistant flame retardancy of 5 to 20 Mrad of an electron beam applied to a flame retardant composition comprising 151 to 300 parts by weight of a flame retardant and 1 to 10 parts by weight of a silane coupling agent with respect to 100 parts by weight of a resin component comprising 15% by weight It is a composition.
In a preferred embodiment, the flame retardant is magnesium hydroxide that has not been surface-treated or a mixture of magnesium hydroxide and aluminum hydroxide that has not been surface-treated, and the silane coupling agent is represented by the general formula (1). The heat-resistant flame retardant composition having the structure shown.
[Chemical formula 2]
(R represents an alkyl group having a methacryl group or an acryl group, and Y ¹ , Y ² , and Y ³ represent an atomic group selected from the group consisting of an alkyl group and an alkoxyl group.)
Furthermore, the present invention is an electric wire / cable having the heat-resistant and flame-retardant resin as a sheath layer or an insulating layer.
[0005]
DETAILED DESCRIPTION OF THE INVENTION
The ethylene-vinyl acetate copolymer (EVA) used in the present invention has a high EVA and VA content even when EVA having a vinyl acetate (VA) content of 25 to 45% by weight is used alone. You may use what adjusted VA content to 25 to 45 weight% by mixing low EVA or polyethylene (PE). The VA content is required to be 25 to 45% by weight, and preferably 30 to 35% by weight. When the VA content of EVA is less than 25% by weight, the flame retardancy of the final flame retardant composition becomes insufficient, and when it exceeds 45% by weight, strength reduction and blocking occur.
[0006]
The unsaturated carboxylic acid-modified polyolefin resin used in the present invention is not particularly specified, but examples of the unsaturated carboxylic acid include monobasic acids and dibasic acids such as acrylic acid, methacrylic acid, maleic acid, and fumaric acid. Examples include acids or metal salts, amides, imides, esters or anhydrides of the above unsaturated carboxylic acids. Most preferred is maleic anhydride, and the modification rate is suitably 0.05 to 5% by weight. The polyolefin resin to be modified is not particularly defined, but LLDPE, PP, and the like are preferable from the viewpoint of strength and heat resistance.
The blending amount of the unsaturated carboxylic acid-modified polyolefin resin needs to be in the range of 0.5 to 15% by weight with respect to the resin component. If the blending amount is less than 0.5% by weight, the inorganic material aggregates and the molded appearance deteriorates. If it exceeds 15% by weight, it is not preferable because it is not flexible and flame retardancy is lowered.
[0007]
The flame retardant used in the present invention is preferably a metal hydroxide that has not been surface-treated, more preferably magnesium hydroxide that has not been surface-treated, or magnesium hydroxide and aluminum hydroxide that have not been surface-treated. It is a mixture. The mixing ratio of non-surface-treated aluminum hydroxide to the total amount of non-surface-treated metal hydroxide is preferably 1/2 or less, and more preferably 1/3 or less. When the mixing ratio of the aluminum hydroxide to the total amount of the metal hydroxide not subjected to the surface treatment exceeds 1/2, the molded appearance deteriorates due to foaming due to temperature rise during kneading.
The average particle size of the metal hydroxide that has not been surface-treated is preferably 5 μm or less, and more preferably 2 μm or less. When the average particle size exceeds 5 μm, not only the flame retardancy of the final flame retardant composition becomes insufficient, but also the stickiness becomes worse and the molded appearance becomes worse.
Here, when magnesium hydroxide surface-treated with a fatty acid metal salt or the like is used, the tensile elongation is increased, but the tensile strength and flame retardancy are extremely reduced. Further, the heat aging characteristics increase the rate of change in strength and elongation, which is not preferable.
The surface-treated metal hydroxide was modified with unsaturated carboxylic acid and 99.5 to 75% by weight of ethylene-vinyl acetate copolymer (EVA) having a vinyl acetate (VA) content of 25 to 45% by weight. The blending amount of the polyolefin resin with respect to 100 parts by weight of the resin component composed of 0.5 to 25% by weight is preferably 151 to 300 parts by weight, and more preferably 180 to 240 parts by weight. If it is less than 151 parts by weight, the flame retardancy of the final flame retardant composition will be insufficient, and if it exceeds 300 parts, the extrusion torque will increase, and the moldability will suddenly deteriorate.
[0008]
The silane coupling agent used in the present invention has a structure represented by the formula (1). Preferably, γ-methacryloxypropylmethoxysilane, γ-methacryloxypropyltriethoxysilane, γ-methacryloxypropyldimethoxymethylsilane, γ-methacryloxypropyltrimethoxysilane, more preferably γ-methacryloxypropyltrimethoxy. Silane.
Further, the added amount is preferably 1 to 10 parts by weight with respect to 100 parts by weight of the resin component, and if it is less than 1 part by weight, the extrusion torque is increased, there is a problem in workability, and the flame retardancy is insufficient. If it exceeds 10 parts by weight, the stickiness becomes worse. Further, as an addition method, it may be added as it is, or may be subjected to a surface treatment in addition to magnesium hydroxide or a mixture of magnesium hydroxide and aluminum hydroxide.
[0009]
About the irradiation amount of an electron beam, it is required to be 5-20 Mrad. The acceleration voltage is preferably 750 Kv, and the irradiation amount is preferably 10 to 15 Mrad. When the irradiation dose is less than 5 Mrad, the flame retardancy is insufficient, and when it exceeds 20 Mrad, the shell formation becomes worse and the shell falls during combustion.
In addition, a colorant, an antioxidant, an ultraviolet absorber, a processing aid, a stabilizer and other additives are blended in the composition of the present invention as necessary within a range not inhibiting the effects of the present invention. Can do.
The flame retardant composition of the present invention can be easily produced by uniformly mixing the above-described components using an ordinary batch kneader such as a Banbury mixer or a pressure kneader.
These flame retardant compositions can be used to coat electric wires and cables using a single screw extruder or the like.
[0010]
【Example】
EXAMPLES Hereinafter, although an Example demonstrates this invention, this is only a mere illustration and this invention is not limited to this.
Various materials shown in Table 1 to Table 4 were kneaded with a pressure kneader for 3 minutes, and were formed into a sheet with an open roll, pulverized with a sheet pelletizer, and extruded into a sheet with a single screw extruder at 180 ° C. It was pressure molded for 1 minute and adjusted to a predetermined thickness. Moreover, a simple electric wire shape was created by coating various materials with a thickness of 0.8 mm on a steel wire having an outer diameter of φ1.2 mm with a single screw extruder. Those sheets or simple electric wire test pieces were irradiated with an electron beam having an acceleration voltage of 750 kV at a dose of 3 to 30 Mrad.
[0011]
Various evaluations were performed based on the following.
(1) Tensile properties: A JIS dumbbell No. 3 test piece was prepared from a press sheet having a thickness of 1 mm, and a tensile test was performed at a speed of 200 mm / min with a tensile tester.
(2) Flame retardancy: A combustion test (based on UL1581: VW-1) was performed with the above simple electric wire test piece.
(3) Heat aging test: heat treatment is performed at an aging condition of 136 ° C. × 168 hours, the tensile strength and elongation after the treatment are measured, and the residual rate is obtained from the normal value.
-Symbols and criteria-
○: Residual rate of tensile strength 70% or more and elongation residual rate 65% or more X: Otherwise (4) Molding workability: Molding workability was evaluated by extruding from a single screw extruder.
○: Extrusion torque is low and molding processability is good ×: Extrusion torque is high and molding processability is poor (foaming or undulation occurs or the extruder itself stops)
(5) Molding appearance: The surface of the molded product was visually determined.
○: When the surface of the molded product is smooth ×: Confirmation of inorganic aggregates, irregularities, bleed, bloom, etc.
The raw materials used in the table are as follows.
* 1 EVA (VA Ccontent = 25%): Everflex P2505C (Mitsui DuPont Chemical Co., Ltd.)
* 2 EVA (VA Ccontent = 40%): Everflex EV40LX (Mitsui DuPont Chemical Co., Ltd.)
* 3 Maleic anhydride modified LLDPE: Adtex L-6101M (manufactured by JPO Corporation; polar group modification rate = 0.2 wt%)
* 4 Surface untreated magnesium hydroxide: Kisuma 5 (Kyowa Chemical Co., Ltd.)
* 5 Silane coupling agent: KBM503 (manufactured by Shin-Etsu Scientific Co., Ltd.): γ-methacryloxypropyltrimethoxysilane
* 6 Antioxidant: Irganox 1010 (manufactured by Ciba Geigy Japan)
* 7 EVA (VA Ccontent = 21%): Everflex EV-210 (Mitsui DuPont Chemical Co., Ltd.)
[0013]
[Table 1]
[0014]
[Table 2]
[0015]
[Table 3]
[0016]
[Table 4]
[0017]
【The invention's effect】
According to the present invention, no halogen-based gas is generated during combustion, high flame retardancy and heat resistance, good mechanical strength, high filling of flame retardant without deteriorating molding processability and molding appearance It is possible to provide a non-halogen flame retardant composition.

Claims (2)

99.5 to 85% by weight of ethylene-vinyl acetate copolymer (EVA) having a vinyl acetate (VA) content of 25 to 45% by weight and 0.5 to 15% by weight of a polyolefin resin modified with an unsaturated carboxylic acid, comprising a resin component based on 100 parts by weight, flame retardant 151-300 parts by weight, heat resistance flame retardant composition that 5~20Mrad irradiated with an electron beam of a silane coupling agent 1 to 10 parts by weight of the flame retardant composition prepared by blending A heat-resistant flame-retardant composition , wherein the flame retardant is magnesium hydroxide that has not been surface-treated, and the silane coupling agent has a structure represented by the general formula (1) .
(R represents an alkyl group having a methacryl group or an acryl group, and Y ¹ , Y ² , and Y ³ represent an atomic group selected from the group consisting of an alkyl group and an alkoxyl group.) The electric wire and cable which have the heat-resistant flame-retardant composition of Claim 1 as a sheath layer or an insulating layer.