JPH04270743A - Flame-retardant polymer composition - Google Patents

Abstract

PURPOSE:To obtain an olefinic polymer composition having high flame retardance, not evolving a poisonous gas and a large amount of smoke during combustion, having excellent mechanical characteristics and processing properties. CONSTITUTION:100 pts.wt. olefinic resin is blended with 50-200 pts.wt. hydroxyl group-containing compound of magnesium and/or aluminum, 1-30 pts.wt. zinc oxide having >=20m<2>/g specific surface area measured by BET method and 0.1-20 pts.wt. silicone oil to give a flame-retardant olefinic polymer composition which has excellent mechanical characteristics, processing properties and flame retardance to reach V-0 level in UL standard, and is suitably usable as a coating material for electric wire, cable, etc.

Description

[Detailed description of the invention]

0001

FIELD OF THE INVENTION This invention relates to flame retardant polymer compositions. More particularly, the present invention relates to improved flame-retardant polymer compositions based on olefin polymers suitable for sheathing of electric wires, cables, etc.

0002

[Prior art and its problems] Olefin polymers are widely used as electrical insulating materials because they generally have excellent electrical properties, mechanical properties, processability, etc.; however, they are easily flammable. Depending on the application, it may be necessary to make it flame retardant. One way to do this is to add halogen-based flame retardants such as chlorides and bromides, but these halogen-based flame retardants have the disadvantage of emitting toxic gases, corrosive gases, and large amounts of smoke when burned. Therefore, in recent years, methods using inorganic hydroxide flame retardants such as magnesium hydroxide and aluminum hydroxide have been widely studied. However, there is a limit to the amount of inorganic hydroxides that can be added due to processability and other physical property constraints, so it is not possible to increase the flame retardance to a satisfactory level by using a single inorganic hydroxide. I couldn't.

[0003] In order to improve these drawbacks, methods have been proposed in which various additives are used in combination, but satisfactory results have not always been obtained. The reason for this is that it is not enough to simply improve flame retardancy for the outer sheath of electric wire cables, but it is necessary to improve flame retardancy while maintaining a certain level of processability and other properties. However, this was accompanied by technical difficulties. For example, JP-A-63-159473 proposes a method of using silicone oil in combination with an inorganic hydroxide flame retardant. Although it is true that the oxygen index is improved by the combined use of silicone oil, it was not easy to achieve the V-0 level according to the American UL-94 (Underwriters Laboratory) standard with such a prescription. In addition, a method of using zinc oxide together with an inorganic hydroxide flame retardant was disclosed in JP-A-63-1280.
No. 40 and JP-A-2-18434, but this formulation does not improve flame retardancy sufficiently, and as the former proposal suggests, an auxiliary agent with a higher flame retardant effect such as red phosphorus may be used. Improvement in flame retardance could not be achieved without the use of .

0004

[Problems to be Solved by the Invention] The present inventors have developed a flame-retardant formulation by adding inorganic hydroxide to polyolefin, without substantially impairing various properties such as mechanical strength and processability.
In the process of searching for flame retardant aids that meet L-94 standards,
We came up with the idea of using the above-mentioned silicone oil in combination with zinc oxide, which cannot be expected to have a significant effect when added alone, and conducted studies hoping for a synergistic effect. No improvement was observed. However, when a special zinc oxide, that is, zinc oxide with a specific specific surface area, is used, surprisingly, the effect of the combined addition with silicone oil becomes remarkable, and it is possible to obtain a flame-retardant olefin polymer composition at the target level. The present invention was achieved based on the discovery that the following can be obtained.

[0005] Accordingly, an object of the present invention is to provide a flame-retardant polymer composition which has excellent properties such as mechanical strength and processability, and which has further improved flame retardancy.

[0006]

Means for Solving the Problems The present invention provides 50 to 200 parts by weight of a magnesium and/or aluminum hydroxyl group-containing compound to 100 parts by weight of an olefin polymer;
This is a flame-retardant polymer composition containing 1 to 30 parts by weight of zinc oxide having a specific surface area of 20 m2/g or more as measured by the ET method and 0.1 to 20 parts by weight of silicone oil.

[0007] The olefin polymer used in the present invention is
Homopolymers of olefins, copolymers of olefins,
It is one type or a mixture of two or more types selected from copolymers of olefins and monomers other than olefins. These may be highly crystalline, low crystalline or amorphous polymers. Further, the copolymer may be a random copolymer, a block copolymer, a graft copolymer, or the like. Specifically, polyethylene, polypropylene, poly-1-butene, poly-4-methyl-1-pentene, ethylene and a small proportion of other olefins such as propylene, 1-butene, 1-hexene, 1-octene, 1- Copolymers with decene, 4-methyl-1-pentene, etc., propylene with small proportions of other olefins, such as ethylene, 1-butene, 1-
Copolymers with hexene etc., 1-butene copolymers, ethylene/propylene/diene copolymers, ethylene/vinyl acetate copolymers, ethylene/(meth)acrylic acid copolymers,
Ethylene/(meth)acrylic acid ester copolymer (herein, (meth)acrylic acid refers to acrylic acid or methacrylic acid, and (meth)acrylic acid ester refers to acrylic ester or methacrylic ester), e.g. Ethylene/methyl (meth)acrylate copolymer, ethylene/ethyl (meth)acrylate copolymer, ethylene/methyl acrylate copolymer,
Isobutyl (meth)acrylate copolymer, ethylene (
n-butyl meth)acrylate copolymer, ethylene/vinyl acetate/maleic anhydride copolymer, ethylene/(meth)acrylic acid/(meth)acrylic acid ester copolymer,
Examples include ethylene/(meth)acrylic acid ester/carbon monoxide copolymers, and graft copolymers of maleic anhydride, himic acid, etc. using these polymers as the backbone polymer.

Although it varies depending on the purpose of use, for example, ethylene/(meth)acrylic acid is used as an olefin polymer for coating electric wires, cables, etc. from the viewpoint of strength, low temperature characteristics, flex whitening resistance, acid resistance, etc. An ester copolymer and a low-crystalline or non-crystalline ethylene/α-olefin copolymer having a density of 0.89 g/cm3 or less, which is partially or wholly graft-modified with an unsaturated carboxylic acid or its anhydride. Preferably, blends are used.

[0009] Such an ethylene/(meth)acrylic acid ester copolymer has an ethylene content of, for example, 8.
The melt flow rate (190°C, 2
160g load) is 0.1 to 200g/10 minutes, preferably 0.1 to 30g/10 minutes.

The ethylene/α-olefin copolymer partially or wholly graft-modified with an unsaturated carboxylic acid or its anhydride is a modified ethylene/α-olefin copolymer or a modified ethylene/α-olefin copolymer. It means a blend of unmodified ethylene/α-olefin copolymer, and the grafted unsaturated carboxylic acid or its anhydride is present in a proportion of, for example, 0.1 to 5% by weight, preferably 0.1 to 3% by weight. exist. Ethylene α- as the backbone polymer
Suitable olefin copolymers are ethylene/propylene copolymers and ethylene/1-butene copolymers, with ethylene/1-butene copolymers being particularly preferred. Also, the melt flow rate is 0.1 to 100g/1
0 minutes, particularly preferably 1 to 10 g/10 minutes.

[0011] The ratio of the ethylene/(meth)acrylic acid ester copolymer and the partially or wholly graft-modified ethylene/α-olefin copolymer is, for example, the former 2.
0 to 90% by weight, preferably 30 to 70% by weight,
The latter is 10 to 80% by weight, preferably 30 to 70% by weight.

[0012] In addition to these two components, low density polyethylene, ethylene α with a density exceeding 0.89 g/cm3
- A composition in which an olefin copolymer, ethylene/vinyl acetate copolymer, etc. is added to the above two-component mixture in a proportion of 50% by weight or less, preferably 5 to 30% by weight, is also suitable for the same purpose. It is.

One component of the flame retardant used in the present invention is a magnesium and/or aluminum hydroxyl group-containing compound. The above magnesium or aluminum hydroxyl group-containing compound is a compound containing at least one hydroxyl group per 1 atom of magnesium or aluminum, and more specifically includes magnesium hydroxide, aluminum hydroxide, basic magnesium carbonate, hydrotalcite, etc. It is one type or a mixture of two or more types selected from. Of course, these may be surface-treated with silane coupling agents, titanate coupling agents, higher fatty acids or their salts, higher alcohols, surfactants, etc., and the use of these may improve dispersibility, processability, and scratch resistance. It is preferable from the viewpoint of properties and whitening resistance. The above flame retardant preferably has an average particle size of 20 μm or less, particularly 5 μm or less. The amount of these hydroxyl group-containing compounds used is 50 to 200 parts by weight, preferably 80 to 150 parts by weight, based on 100 parts by weight of the olefin polymer.

In the present invention, zinc oxide is blended in addition to the hydroxyl group-containing compound. The above-mentioned zinc oxide may be manufactured by any method such as French method, American method, or wet method, but its specific surface area is determined by BET method to be 2.
0m2/g or more, preferably 30-200m2/g
are used. A specific example of such zinc oxide is activated zinc white ZINCA-20 manufactured by Sakai Chemical Industry Co., Ltd.
can be mentioned. The amount of zinc oxide blended is 1 to 30 parts by weight, preferably 5 to 20 parts by weight, per 100 parts by weight of the polymer component. If this amount is too large, mechanical strength, workability, etc. will be significantly reduced, which is not preferable. Of course, surface-treated zinc oxide may be used.

In addition to the above two types of inorganic flame retardant additives, silicone oil is added to the composition of the present invention. Silicone oils of various viscosities can be used, for example those having a viscosity of 10 to 100,000 centistokes at 25°C can be used. Of course, it is also possible to use a material with a higher viscosity or a material that is solid at room temperature. The silicone oil may be pure silicone oil or modified silicone oil such as fatty acid-modified silicone oil. The use of such modified silicone oil is advantageous in that it bleeds onto the polymer surface and is less sticky. The amount of silicone oil added is 0.1 per 100 parts by weight of the polymer component.
-20 parts by weight, preferably 1-10 parts by weight.

[0016] In addition to the above-mentioned essential ingredients, the composition of the present invention includes:
Depending on the purpose of use, other flame retardants or flame retardant aids, antioxidants, heat stabilizers, anti-aging agents, ultraviolet absorbers, pigments,
Dyes, other inorganic fillers, etc. can be blended. For example, carbon black, talc, clay,
Calcium carbonate, red phosphorus, phosphate ester, etc. may also be blended.

The composition of the present invention can be produced by blending the above-mentioned essential components and optionally additional components and kneading them using a conventional kneading method such as a Banbury mixer, a roll, or a continuous kneading extruder.

[0018]

[Example] Examples 1 to 5 Ethylene-ethyl acrylate copolymer (EEA) and ethylene-1-butene copolymer (E
BR), graft-modified EBR, and LLDPE, magnesium hydroxide, zinc oxide, and silicone oil as flame retardants at the blending ratios shown in the upper column of Table 1, are put into a 6-inch roll and kneaded by rolls to produce a flame-retardant olefin. A polymer composition was produced. After kneading, press molding to a thickness of 1m
A 3 mm sheet was used for evaluation of tensile properties and flame retardancy. Tensile properties were measured using a press sheet with a thickness of 1 mm.
JIS K as No. 3 test piece of JIS K6301
Measured in accordance with 6760. In addition, flame retardancy is Unde
Evaluation was made in accordance with the safety standard UL94 of rwriters Laboratories. The results are shown in the lower column of Table 1.

Comparative Examples 1 to 6 Flame-retardant polymer compositions were prepared in the same manner as in the examples using the blending ratios shown in the upper column of Table 2, and evaluated in the same manner. The results are shown in the lower column of Table 2.

The contents of the ingredients shown in the table are as follows. (1) Polymer EEA: ■MFR0.5g/10min, ethyl acrylate content 15
Weight% of ethylene-ethyl acrylate copolymer■MFR
0.5 g/10 min, ethylene-ethyl acrylate copolymer graft modified EB with ethyl acrylate content of 25% by weight
R: MFR 3.6 g/10 min, density 0.88 g/cm3 100 parts by weight of ethylene-1-butene copolymer, 0.55 parts by weight of maleic anhydride and organic peroxide (2,5-dimethyl-2, MFR obtained by melting and reacting 0.2 parts by weight of 5-bis(t-butylperoxy)hexane (brand name "Lupasol 101") at 250°C in an extruder.
2.5 g/10 min, density 0.88 g/cm3, maleic anhydride grafted ethylene-1-butene copolymer EBR with maleic anhydride content 0.5% by weight: MFR 3.6 g/10 min, density 0.88 g /cm3 of ethylene-1-butene copolymer LLDPE: MFR2.0g/10min, density 0.910g/cm3
ethylene-4-methyl-1-pentene copolymer of

002
1) (2) Additive magnesium hydroxide: Kisuma 5A zinc oxide manufactured by Kyowa Chemical Co., Ltd. ■Activated zinc white ZINCA-20 manufactured by Sakai Chemical Industry Co., Ltd. (specific surface area 60 m2 /g) ■Fine zinc white manufactured by Sakai Chemical Industry Co., Ltd. Surface area 13m2/g
) Higher fatty acid modified silicone oil: TSF410 manufactured by Toshiba Silicone Company Silicone oil: TSF451-30 manufactured by Toshiba Silicone Company

[0022]

[Table 1]

[0023]

[Table 2]

As is clear from the results in Tables 1 and 2, the specific surface area measured by the BET method in the flame retardant formulation is 20 m2/
Example 1 using silicone oil with zinc oxide in an amount of more than 100 g
The olefin polymer composition of ~5 shows high flame retardancy,
We were able to achieve UL94 V-0. On the other hand, the specific surface area is 20
The compositions of Comparative Examples 1 to 4, which are formulations that use a combination of zinc oxide and silicone oil of less than m2 /g, formulations that do not add zinc oxide, or formulations that do not add silicone oil, have insufficient flame retardancy and have a UL94 V rating. -0 could not be achieved.

[0025]

[Effects of the Invention] The flame-retardant polymer composition of the present invention can achieve a high degree of flame retardancy, and has excellent mechanical properties and processability. That is, according to the present invention, a flame-retardant olefin polymer composition that reaches the level of V-0 in the UL standard can be easily obtained. Since the composition of the present invention does not generate toxic gas, corrosive gas, or large amounts of smoke when burned, it can be particularly suitably used as a coating material for electric wires, cables, etc.

Claims (1)

[Claims] Claim 1: 100 parts by weight of an olefin polymer, 50 to 200 parts by weight of a magnesium and/or aluminum hydroxyl group-containing compound, 1 to 30 parts by weight of zinc oxide having a specific surface area of 20 m2/g or more as measured by the BET method. ,
A flame-retardant polymer composition containing 0.1 to 20 parts by weight of silicone oil.