JPH03215540A - Polyolefin resin composition - Google Patents

Abstract

PURPOSE:To obtain a resin composition nor undergoing whitening caused by carbon dioxide by mixing a polyolefin with magnesium hydroxide surface-treated with a stearic acid surface treatment and zinc oxide. CONSTITUTION:A resin composition prepared by mixing 100 pts.wt. polyolefin resin with 50-200 pts.wt. magnesium hydroxide surface-treated with a stearic acid surface treatment and 0.1-10 pts.wt. zinc oxide. The zinc oxide used may be usual one not surface-treated or one surface-treated with a stearic acid, silane, titanate or like surface treatment. The above resin composition may be one chemically crosslinked with, e.g. dicumyl peroxide or one crosslinked by irradiation with, e.g. electron beams.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a flame-retardant polyolefin resin composition containing magnesium hydroxide and zinc oxide that have been subjected to a specific surface treatment.

[Prior Art and its Problems] Conventionally, flame retardant resin compositions that do not use halogens, especially in the case of polyolefin resins, have been widely used that contain magnesium hydroxide as a flame retardant. However, when these flame-retardant regreased compositions or molded products using them are exposed to a high humidity environment,
Magnesium hydroxide blended in the composition reacts with carbon dioxide and moisture in the atmosphere, and the produced magnesium carbonate precipitates on the surface of the composition or molded product, causing a white powder-like appearance B (hereinafter referred to as (This is called carbon dioxide whitening), which lowers the commercial value and, if the precipitation is significant, may also lead to a decrease in flame retardancy.

This carbon dioxide whitening can be improved to some extent by lowering the amount of magnesium hydroxide, but on the other hand,
Until now, there have been no effective measures to prevent carbon dioxide whitening that can be put to practical use because the flame retardance is significantly reduced.

[Means for Solving the Problems] The present invention provides a solution in which carbon dioxide whitening does not substantially occur even when magnesium hydroxide is blended in an amount that can impart sufficient flame retardance to a polyolefin resin. The present invention relates to a flame-retardant polyolefin resin composition that cannot be used.

In the present invention, based on 100 parts by weight of polyolefin resin,
50 to 200 parts by weight of magnesium hydroxide and 0.1 to 10 parts by weight of zinc oxide surface treated with a stearic acid-based surface treatment agent
Parts by weight of the polyolefin resin composition.

Examples of the polyolefin resin include ethylene homopolymers such as polyethylene, polypropylene, and polybutene-1, ethylene copolymers such as ethylene-propylene copolymers, ethylene-vinyl acetate copolymers, and ethylene-(meth)acrylate copolymers; Examples include elastomers such as ethylene-propylene rubber and ethylene-propylene-diene rubber. These polyolefin resins may be used alone or in combination of two or more. In addition, polyolefin resins modified with unsaturated carboxylic acids and their anhydrides or vinyl alkoxysilanes can also be used to improve adhesion and the like.

The surface of the magnesium hydroxide used in the present invention is treated with a stearic acid-based anionic surfactant such as sodium stearate and potassium stearate. Its average grain size is 0.01~50μ steel, especially
Preferably, it has an Irm of 0.05 to 10 tIrm. The compounding amount is
50 to 200 parts by weight of polyolefin resin
Parts by weight, particularly in the range from 70 to 150 parts by weight, are preferred.

In the present invention, in addition to the above, polyolefin resin 100
Based on parts by weight, 0. 1 to 10 parts by weight, particularly preferably 0.3 to 5 parts by weight, of zinc oxide are added.

By adding this zinc oxide, the unique effects of the present invention can be obtained. Zinc oxide that is generally commercially available can be used, but zinc oxide with an average particle size of 0.01 to 50 μ-, especially
0.01 to 10μ is preferable. Zinc oxide may be a normal zinc oxide without surface treatment, or may be treated with a surface treatment agent such as stearic acid, silane, or titanate. If the amount of zinc oxide is less than 0.1 part by weight, the effect of preventing carbon dioxide whitening will not be sufficient, and if it exceeds 10 parts by weight, not only will no further improvement in the effect of preventing carbon dioxide whitening be observed. Physical properties such as mechanical strength and flame retardancy are unfavorable.

In addition to the above-mentioned ingredients, the resin composition of the present invention may contain various known additives, such as antioxidants, ultraviolet absorbers, pigments, etc., to the extent that they do not impair the effects of the present invention. . Further, the resin composition of the present invention may be crosslinked by a method such as chemical crosslinking using dicumyl peroxide or the like or radiation crosslinking by irradiation with an electron beam or the like.

The resin composition of the present invention can be obtained by suitably blending the above-mentioned components and uniformly melt-kneading them using a known device such as a two-wheel kneading extruder or a Banbury mixer.

The present invention will be explained in more detail below using Examples and Comparative Examples.

Examples and comparative examples Table 1 shows the formulations of Examples 1 to 6 and Comparative Examples 1 to 7.

The composition of each example was prepared by dry-blending each component for 10 minutes at room temperature to give a sufficiently uniform mixture, and then kneading the mixture using a Banbury mixer at a temperature of 180°C. The mixture was melted and kneaded for 4 hours and 15 minutes to form a belent. These pellets were molded into a sheet measuring 5A++ long, 3 cm wide, and law thick using a hot press.
32A (manufactured by Cabot Corporation)] was added in an amount of 2 parts by weight to the polyolefin resin. The specimen was left for 48 hours in a constant temperature and humidity chamber set in an atmosphere of 100% carbon dioxide, temperature 50°C, and humidity 95%, and after being taken out and dried, the whitening state of the specimen surface was visually observed.
The results are shown in Table 2. In addition, each symbol in Tables 1 and 2 indicates the following, respectively.

Bo1 Olefin 12 R-1: Ethylene-ethyl acrylate copolymer R-2:
Ethylene-vinyl acetate copolymer R-3 = Maleic anhydride modified polyethylene mag. Spring X-1: Basic zinc carbonate X-2 Aluminum dioxide X-3: Magnesium oxide In comparison, the carbon dioxide whitening properties of Examples 1 to 5 are significantly superior despite the large amount of magnesium hydroxide in the composition. Magnesium hydroxide treated with a treatment agent is used.In this case, even if zinc oxide is added, the effect of preventing carbon dioxide whitening cannot be obtained.

In Comparative Examples 3 to 6, zinc compounds or metal oxides other than zinc oxide were blended, but it can be seen that these do not have the effect of preventing carbon dioxide whitening.

Comparative Example 7 contains a large amount of zinc oxide, but
The mechanical properties are significantly deteriorated and it cannot be put to practical use.

〔Effect of the invention〕

It has been known for a long time to incorporate magnesium hydroxide into polyolefin resins to improve their flame retardancy. However, when magnesium hydroxide is added in an amount that can sufficiently improve flame retardancy, magnesium hydroxide reacts with moisture and carbon dioxide, and magnesium carbonate is produced over time.
A problem has been so-called carbon dioxide whitening that is blown out onto the surface of resin compositions or molded products.

In the present invention, by further blending zinc oxide with polyolefin resin and magnesium hydroxide that has been subjected to a specific surface treatment, it is possible to sufficiently improve flame retardancy without deteriorating mechanical properties. It can also prevent gas whitening.

Claims (1)

[Claims] 5 parts of magnesium hydroxide surface-treated with a stearic acid-based surface treatment agent per 100 parts by weight of polyolefin resin
A polyolefin resin composition containing 0 to 200 parts by weight and 0.1 to 10 parts by weight of zinc oxide.