JP2648874B2 - Heat-resistant polyolefin composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial application field) The present invention has high flame retardancy capable of passing the flame contact test UL94V-0 standard of the United States UL standard, as well as mechanical strength and The present invention relates to a flame-retardant polyolefin composition having excellent electric properties and suitable for application to, for example, insulating materials and sheath materials of electric wires and cables.

(Prior art) Polyolefin is an inexpensive resin with excellent electrical insulation properties, and it is easy to improve mechanical strength, heat deformation resistance, etc. by performing radiation (eg, electron beam) irradiation crosslinking or chemical crosslinking. Since it is possible, it is widely used as an insulating layer or a sheath layer of an insulated wire for wiring in a device.

However, polyolefin itself is a flammable substance, and in recent years, when polyolefin is applied to the aforementioned applications,
From the viewpoint of safety and fire prevention, it was necessary to impart high flame retardancy to polyolefin. To give an example of the proposal,
In JP-A-53-60944, the use of a flame retardant obtained by combining a polyethylene polymer with a mixture of a chlorine-containing flame retardant and a bromine-containing flame retardant in a specific ratio, and further combining antimony trioxide, has been proposed. A polyolefin composition having obtained the flame retardancy of the present invention is shown. JP-A-53-141353 discloses a flame-retardant polyolefin composition obtained by combining a polyolefin copolymer with a halogen-based flame retardant or a phosphorus-containing flame retardant, and with specific amounts of antimony trioxide and aluminum hydroxide. I have.

(Problems to be Solved by the Invention) The object of using a flame-retardant polyolefin wire formed by extruding a flame-retardant polyolefin composition onto a conductor and crosslinking the same is to use the above-mentioned insulated wire for wiring in equipment. The flame-retardant polyolefin composition must be a highly flame-retarded composition and requires a high balance of heat resistance, mechanical strength, electrical properties and material costs. For example, in the flame-retardant technology according to the above-mentioned JP-A-53-60944, it is possible to obtain a composition that passes the vertical combustion test of the U.S.A.UL Standard Subject 758, but the tensile strength characteristics of the obtained composition are as follows. It is a little higher than the standard (1.05 kgf / mm ² ) specified in the US UL standard, and cannot be said to be sufficiently satisfactory in consideration of the variation in tensile strength. Also, the aforementioned Japanese Patent Application Laid-Open No. 53-1413
In the flame-retarding technique according to JP-A-53-53, aluminum hydroxide is incorporated in a large amount, and as described in the section of the problem to be solved by the invention of JP-A-60-252646, polyolefin is generally used. The flame-retardant composition obtained by blending a large amount of aluminum hydroxide into the mixture has the disadvantage that the tensile properties and processing properties are degraded, and the appearance of the molded article is likely to be poor.

By simply applying the conventional flame retarding method as described above, only insufficient flame retardancy can be obtained, mechanical strength decreases, or material cost increases due to a large amount of expensive flame retardant compounded. There was an inconvenience that it was difficult to balance the characteristics, such as causing the cause. That is, within the scope of the prior art,
If a flame retardant is blended with a polyolefin-based resin to obtain advanced flame-retardant properties, it tends to lose its balance with other mechanical properties and properties such as heat resistance. It was necessary to find a combination that was excellent and had a property of being more easily made flame-retardant by the incorporation of a flame retardant, and an effective combination with a smaller amount of a flame retardant. In general, by blending a flame retardant with a polyolefin, or by using a polyolefin having a property that makes it more flame-retardant, a decrease in electric insulation is likely to occur, and a high electric property (volume resistivity 1 × 10 ¹⁶ Ω) is obtained. (Cm or more), further improvement has been desired for applications requiring the use of such a material.

(Means for Solving the Problems) In order to solve the above-mentioned problems, the present inventors balance the flame-retardant properties of polyolefins, which are inexpensive and easily extruded, with other properties, especially electrical properties, and As a result of various investigations to improve without increasing the material cost significantly, a polyolefin composition containing an ethylene-vinyl acetate copolymer and having a vinyl acetate component content of 6 to 15% by weight in the composition 100 parts by weight, brominated flame retardant 20
~ 40 parts by weight, 10 ~ 30 parts by weight of antimony trioxide, 10 ~ 60 parts by weight of magnesium hydroxide, 2 ~ 20 parts by weight of a zinc compound, and 0.5 ~ 5 parts by weight of an ethylene-propylene copolymer modified with an organopolysiloxane By blending the parts, the flame retardant properties of the polyolefin composition are balanced with other properties, especially electrical properties, and the flame retardant polyolefin composition has been significantly improved without causing a significant increase in material cost. I found it.

The polyolefin composition containing 6 to 15% by weight of the vinyl acetate component according to the present invention is defined as having a vinyl acetate component content of
When the ethylene-vinyl acetate copolymer determined by the measurement method specified in JISK6730-1981 is A, and the polyolefin resin excluding the ethylene-vinyl acetate copolymer is B,
The vinyl acetate component content with respect to the mixture of A and B is
Polyolefin compositions which are calculated to be between 6 and 15% by weight are preferably used. Here, the polyolefin resin excluding the ethylene-vinyl acetate copolymer includes polyethylene, ethylene-α-olefin copolymer, ethylene-propylene copolymer, ethylene-ethyl acrylate copolymer, ethylene-methyl methacrylate copolymer, and the like. Ethylene- (meth) acrylic acid ester binary to ternary copolymers and the like, and may be a mixture of two or more kinds. The polyolefin composition of the present invention has a vinyl acetate content of 6%.
If the content is less than 10% by weight, the flame retardant properties decrease, and if the above-mentioned flame retardant is blended in a large amount to make up for this, the resulting composition becomes expensive and also has a decrease in tensile strength in terms of properties. Significantly, the balance between flame retardancy and tensile properties cannot be maintained. On the other hand, when the content of the vinyl acetate component exceeds 15% by weight, the flame retardancy is sufficient, but the volume resistivity of the composition is unpreferably reduced.

As the brominated flame retardant used in the present invention, those conventionally used can be effectively used. Specific examples include decabulmophenyl oxide, ethylene glycol bis (pentanebromophenyl) ether, hexabromobenzene, tetradecabromodiphenoxybenzene, and tetrabromobisphenol A, and preferably decabromodiphenyl oxide and tetradecabromophenoxybenzene. Is used. If the amount is less than 20 parts by weight, the obtained composition can only obtain insufficient flame retardant properties, and if it exceeds 40 parts by weight, the obtained composition becomes expensive. The tensile strength is undesirably reduced significantly.

As the antimony trioxide used in the present invention, those conventionally used can be effectively used. At this time,
When the amount is less than 10 parts by weight, the obtained composition has insufficient flame-retardant properties.When the amount exceeds 30 parts by weight, the obtained composition is expensive and the tensile strength is significantly reduced. Not preferred.

The magnesium hydroxide used in the present invention is preferably a surface-treated one that is highly miscible with the base polymer, and a suitable one can be easily obtained. At this time, if the blending amount is less than 10 parts by weight, the obtained composition will only have insufficient flame retardant properties, and if it exceeds 60 parts by weight, the resulting composition will have reduced tensile strength and volume resistivity. But not preferred.

As the zinc compound used in the present invention, zinc oxide and zinc borate are preferable, and both are easily available. At this time, when the compounding amount is 2 parts by weight or more, preferably 5 parts by weight or more and 20 parts by weight or less, excellent flame retardancy can be obtained. If the compounding amount is less than 2 parts by weight, the obtained composition can only obtain insufficient flame retardant properties, and if it exceeds 20 parts by weight,
The resulting composition is expensive.

The ethylene-propylene copolymer modified by the organopolysiloxane used in the present invention is generally
SEP rubber, called organopolysiloxane 1-30
% Is common. Further, a material containing a filler or the like may be used. At this time, if the amount is less than 0.5 part by weight, the volume resistivity is not improved, and if it exceeds 5 parts by weight, the tensile strength is undesirably lowered.

The flame-retardant polyolefin composition of the present invention can optionally contain an antioxidant, a crosslinking aid, a lubricant, a coloring agent, an inorganic filler, and the like, if necessary. A crosslinked product may be obtained by means of irradiation crosslinking or chemical crosslinking using an organic peroxide.

(Function) The flame-retardant polyolefin composition of the present invention is applied to a flame-retardant flame resistance test UL94V of the US UL standard on a test piece having a thickness of about 0.8 mm.
−0 standard and tensile strength 1.3kgf / mm ² or more,
Has mechanical properties of elongation of 350% or more and volume resistivity of 1 × 1
It has excellent electrical insulation of 0 ¹⁶ (Ω · cm) or more.

(Example) Hereinafter, the flame-retardant polyolefin composition of the present invention will be described with reference to examples.

As Examples and Comparative Examples, first, the compounded compositions described in Tables 1 and 2 were kneaded on a 6-inch roll at 100 ° C. for 15 minutes, and then vulcanized at 190 ° C. with a press. The sheet was crosslinked by heating under the conditions of a vulcanization time of 10 minutes and a press pressure of 60 kgf / cm ² to obtain a sheet having a thickness of about 0.8 mm. Using these sheets, each evaluation was performed based on JIS C 3005, JIS K 6911, JIS K 6730, and UL 94, and the results are shown in Table 1.

In Comparative Example 1, the vinyl acetate content of the base polymer was 3% by weight according to the composition shown in Table 2.
When a flame contact test was conducted in accordance with UL94 in the United States, all the test pieces had a drip phenomenon, and were judged to be rated at 94V-2 rank. Therefore, the flame retardancy was insufficient. In Comparative Example 2, the vinyl acetate content of the base polymer was 20% by weight.
The volume resistivity of the composition is 1 × 10
^When aiming at ¹⁶ (Ω · cm) or more, the volume resistivity of this composition does not reach the target value. In Examples 1 to 5, the vinyl acetate content of the base polymer was adjusted to 6 to 15% by weight. In any of the compositions, the tensile strength was 1.3 kgf / mm ² or more, the elongation was 350% or more, and the volume resistivity was 1 or more. It was determined to be 94V-0 in the UL94 flame-retardant flame test while maintaining × 10 ¹⁶ (Ω · cm) or more, showing extremely excellent flame-retardant properties. Examples 6 and 7
In the above, 20 parts by weight of ethylene-propylene copolymer was blended with the base polymer, and the vinyl acetate content was 6 and
The composition shown in Table 1 was adjusted to 15% by weight, and all of the tensile properties, flame retardancy properties, and electrical insulation properties showed properties exceeding target values. According to the flame-retardant formulation described in Table 1 described above, by setting the vinyl acetate content of the base polymer to 6 to 15% by weight, a flame-retardant polyolefin composition having balanced properties can be easily obtained. It can be seen that it is obtained.

Next, in Comparative Example 3 and Examples 8 and 9, the vinyl acetate content of the base polymer was adjusted to 12% by weight, and then the content of decabromodiphenyl oxide was adjusted to 10, 20, and 40 parts by weight, respectively. However, in Comparative Example 3, a UL94 flame-retardant flame test was carried out, and it was found that the test pieces were completely burned and thus had poor flame-retardant properties. On the other hand, Examples 8 and 9 are found to be flame-retardant polyolefin compositions excellent in flame-retardant properties with various properties balanced.

Next, in Comparative Example 4 and Examples 10 and 11, the vinyl acetate content of the base polymer was adjusted to 12% by weight, and the amount of antimony trioxide was changed to 5, 10, 30, and parts by weight, respectively. In Example 4, when a UL94 flame-retardant flame test was performed, the luminous combustion time of the test piece was 205 seconds in total,
Since the drip phenomenon was observed, it was determined to be 94V-2, and the flame retardancy was poor. On the other hand, it can be seen that Examples 10 and 11 are flame-retardant polyolefin compositions having excellent balance of various properties and excellent flame-retardant properties.

Next, in Comparative Example 5, Examples 12, 13 and Comparative Example 6, after adjusting the vinyl acetate content of the base polymer to 12% by weight, the mixing amount of magnesium hydroxide was adjusted to 5, 10, 60, and 80 parts by weight, respectively. However, in Comparative Example 5, the flame retardant properties did not reach the target, and in Comparative Example 6, although the flame retardant properties were excellent, the tensile properties and the electrical properties did not reach the targets. In contrast, Examples 12 and 13 were found to be compositions in which various properties were balanced.

Next, in Comparative Examples 7 and 14 and 15, the vinyl acetate content of the base polymer was adjusted to 6% by weight, and in Comparative Example 7, no zinc compound was added. In Examples 14 and 15, boric acid was used. Zinc and Zinhua No. 1 were mixed in 10 parts by weight, respectively. In Comparative Example 7, a test piece having a luminous burning time exceeding a specified time of 94 V-0 in a UL94 flame contact flame retardant test was observed. The drip phenomenon was observed in two of the test specimens, and it was determined to be 94V-2, which did not reach the target. On the other hand, Examples 14 and 15 are compositions having well-balanced properties.

Next, Comparative Examples 8, 9 and Examples 16, 17, 18, and Comparative Example 9 were prepared by adjusting the vinyl acetate content of the base polymer to 12%. Comparative Example 8 was a polyorganosiloxane-modified ethylene-
In the case where the propylene copolymer is not blended,
16, 17, 18 and Comparative Example 9 were those in which the amount of the polyorganosiloxane-modified ethylene-propylene copolymer was 0.5, 1, 5 and 7 parts by weight, respectively, while Comparative Example 8 had a volume resistivity of 5.6 × The target value of 10 ¹⁵ (Ω · cm) and 1 × 10 ¹⁶ (Ω · cm) is not reached. The Comparative Example 9 has a tensile strength does not reach the target value of 1.12kgf / mm ² and low 1.3 kgf / mm ^2. On the other hand, Examples 16, 17, and 18 show values in which the volume resistivity exceeds the target value, and it can be seen that the composition is balanced with other properties.

As is clear from the above Examples, the flame-retardant polyolefin composition of the present invention is a composition having a high level of flame retardancy and a good balance of tensile properties, and also having extremely excellent electrical insulation properties. Is extremely large.

(Effects of the Invention) According to the present invention, a composition that is flexible and has particularly excellent mechanical strength and flame retardancy can be obtained. This composition exhibits flame retardancy equivalent to UL94 V-0 even in a vertical flame retardancy test at a thickness of 1 mm or less, and also exhibits sufficient mechanical strength and electrical insulation performance. After extruding this composition onto a copper wire, a crosslinked polyolefin wire obtained by crosslinking with an organic peroxide is:
It shows a high balance of good appearance, mechanical strength, flame retardancy, electrical insulation, etc., and is flexible, so that it is particularly preferable as an electric wire for wiring in equipment from the viewpoint of workability and workability of assembly. Further, the flame-retardant polyolefin composition of the present invention has a sufficient effect with a relatively small amount of expensive additives such as a flame retardant, and is practically preferable in terms of resistance cost.

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Claims (1)

(57) [Claims] Claims: 1. An ethylene-vinyl acetate copolymer,
100 parts by weight of a polyolefin composition having a vinyl acetate component content of 6 to 15% by weight in the composition and a brominated flame retardant 2
0-40 parts by weight, antimony trioxide 10-30 parts by weight, magnesium hydroxide 10-60 parts by weight, zinc compound 2-20 parts by weight,
And a flame-retardant polyolefin composition comprising 0.5 to 5 parts by weight of an ethylene-propylene copolymer modified with an organopolysiloxane.