JPH05262926A - Flame-retardant polyolefin resin composition - Google Patents

Abstract

PURPOSE:To obtain the subject composition excellent in flame retarding effect, also highly excellent in resistance to whitening by incorporating a polyolefin resin with magnesium hydroxide coated with a specific metal oxide, hydroxide or carbonate. CONSTITUTION:The objective composition having the above-mentioned advantages can be obtained by incorporating (A) a polyolefin resin with (B) 30-75 (pref. 35-60)wt.% of magnesium oxide coated with 0.05-25 (pref. 0.1-15)wt.% of oxide(s), hydroxide(s) or carbonate(s) of at least one kind of metal selected from chromium, molybdenum, vanadium, thorium and cerium, and, where appropriate, (C) such ingredient(s) as flame retarding auxiliary (e.g. antimony trioxide), inorganic filler (e.g. talc, mica), antioxidant, light stabilizer, etc. The above magnesium hydroxide has the following characteristics: (1) particle diameter: pref. <=3mum (esp. <=1.5mum) and (2) BET specific surface area: pref. >=5m<2>/g (esp. >=8m<2>/g).

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a flame-retardant polyolefin resin composition. More specifically, it relates to a flame-retardant polyolefin composition obtained by blending a polyolefin resin with magnesium hydroxide coated with a specific metal oxide, hydroxide or carbonate.

[0002]

2. Description of the Related Art Due to its excellent properties and low price, polyolefin is in the form of injection molded products, films, laminated products, blow molded products, automobiles, building materials, electrical parts, daily necessities, industrial parts. Is widely used as. However,
Polyolefin resins have the drawback of being extremely flammable, and the demand for flame retardancy is increasing as their applications expand.

The flame retardation of organic polymers is (1) adding a flame retardant to the resin, (2) blending the flame retardant resin, (3)
It is carried out by a method such as making a flame-retardant polymer by reaction with a flame-retardant monomer. The most commonly used method among these is to add a flame retardant to the resin, and this method is usually applied to polyolefin resins. As the flame retardant used for these, organic chlorinated compounds,
Halides such as bromides, phosphorus-containing compounds such as phosphoric acid esters, phosphite esters, phosphorus, phosphoric acid and phosphates, water-containing inorganic compounds such as aluminum hydroxide and magnesium hydroxide, and as flame retardant aids. Antimony oxide is commonly used.

[0004]

However, the flame-retardant polyolefins prepared by adding these flame-retardants have their respective drawbacks. For example, although a flame-retardant polyolefin resin prepared by adding an organic halide has a very high flame-retardant effect, it has problems such as blooming of the flame-retardant and poor weather resistance, and further, there is a problem during combustion or processing. There is a suspicion of the generation of toxic gas. In addition, phosphorus compounds have poor compatibility with polyolefin resins, are prone to blooming, are thermally unstable, and there is a possibility that toxic gases such as phosphine are generated. On the other hand, hydrated inorganic compounds are not toxic, and magnesium hydroxide is the most promising non-halogen flame retardant, but its flame retardant effect is small, so a large amount must be added, and the physical properties of the polyolefin resin are significantly impaired. In addition, a whitening phenomenon that the surface of the molded product becomes white is observed, which impairs the appearance of the product.

Several methods have been proposed to remedy the drawbacks of magnesium hydroxide flame retardants. For example, as a method of preventing whitening, saturated fatty acids are added (Japanese Patent Laid-Open No. 53-1).
No. 01037), the surface of magnesium hydroxide is treated with an anionic surface-active agent (JP-A-53-10465).
No. 0) and the like. However, in these methods, although the whitening-preventing effect is reasonable, the effects of improving flame retardancy and physical properties are not recognized.

As a method for improving the flame retardancy, it is used in combination with red phosphorus (JP-A-50-148447), antimony trioxide and an inorganic tin compound (JP-A-53).
No. 30648), an acrylonitrile powder is added (JP-A-53-58548), a metal such as copper, zinc, lead, or a metal oxide is added (JP-A-53-1).
No. 02945), a triallyl trimellitate is added (JP-A-1-141931), and a polysiloxane graft product is added (JP-A-1-182336).
However, in order to bring out these effects, it is necessary to add a large amount of these additives, and it is not possible to substantially reduce the total amount of flame retardants, so improve the physical properties of the resin. Has not reached.

[0007]

Means for Solving the Problems As a result of intensive studies to develop a good flame-retardant polyolefin composition, the present inventors have found that a polyolefin resin contains an oxide of a specific metal,
The present invention was found to be excellent in flame retardant effect and whitening resistance by adding magnesium hydroxide coated with hydroxide and carbonate.

That is, according to the present invention, a hydroxylation is obtained by coating a polyolefin resin with 0.05 to 25 wt% of one or more kinds of oxides, hydroxides and carbonates selected from chromium, molybdenum, vanadium, thorium and cerium. It is intended to provide a flame-retardant polyolefin resin composition having an excellent flame-retardant effect and an extremely excellent whitening resistance by blending 30 to 75 wt% of magnesium.

The smaller the particle size of magnesium hydroxide used in the present invention is, the more preferable it is. Usually, the particle size of 3.0 μm or less is preferable, and the particle size of 1.5 μm or less is more preferable. If the grain size is large, sufficient flame retardancy may not be obtained. Further, the larger the BET specific surface area of the magnesium hydroxide used in the present invention is, the more preferable, and usually 5 m ² /
It is preferably g or more, and more preferably 8 m ² / g or more. When the BET specific surface area is small, a sufficient flame retardant effect may not be obtained.

The method of coating magnesium hydroxide is not particularly limited, but usually, an aqueous solution of a water-soluble salt is precipitated by an appropriate method and the surface of magnesium hydroxide dispersed in water. And the like is used.

The ratio of magnesium hydroxide to the coating agent is 0.05 to 25% by weight, and more preferably 0.1 to 1% by weight.
5 wt% is good. If it is more than 0.05 wt% and more than 25 wt%, the effect will be less.

The amount of magnesium hydroxide treated in this manner is preferably 30 to 75 wt%, more preferably 35 to 60 wt%. If the amount added is less than this, flame retardancy will not be sufficiently exhibited, and if the amount added is greater, physical properties and processability will deteriorate.

Various polyolefin resins can be used in the present invention. As the polyolefin resin used here, polyethylene, polypropylene, an ethylene-vinyl acetate copolymer, an ethylene-ethyl acrylate copolymer, an ethylene-propylene copolymer or a mixture thereof can be used.

Further, in the present invention, those which are usually used as a flame retardant aid, for example, antimony trioxide, an inorganic tin salt and zinc borate can be used in combination. Addition of these improves flame retardancy and suppresses glowing.

It is also possible to improve the physical properties of the present invention by using an inorganic filler in combination. For these purposes,
Talc, mica, silica, calcium silicate, glass fiber, carbon fiber, calcium carbonate and the like are used.

In the present invention, in addition to the above, it is also possible to add those usually used as additives for polyolefin resins, antioxidants, light stabilizers, ultraviolet absorbers and stabilizers.

The flame-retardant polyolefin resin composition thus obtained can be molded into a molded product by a usual processing method such as injection molding, extrusion molding, blow molding and the like.

[0018]

The present invention will be described in detail with reference to the following examples, but the present invention is not limited thereto. still,
Various test methods carried out in Examples and Comparative Examples are as follows.

Flame retardance test Oxygen index: According to JIS K7201 "Combustion test method for polymer materials by oxygen index method".

UL94: According to the UL94 vertical burning test. The test pieces were prepared using an injection molding machine.

Whitening test Using an injection molding machine, a flat plate of 100 × 65 × 3 mm was prepared. 1 in a thermo-hygrostat at a temperature of 70 ° C and a humidity of 90%
After the treatment for 68 hours, it was taken out and visually inspected for the whitening state.

The magnesium hydroxide used in the examples was prepared by the following method. 1. Magnesium hydroxide (1) Average particle size 0.8 micron (BET
2 kg of magnesium hydroxide (manufactured by Kyowa Kagaku KK; Kismer 5A) having a specific surface area of 8 m ² / g) was uniformly suspended. Next, while stirring this suspension, a solution prepared by dissolving 10 g of ammonium molybdate (reagent) in 50 ml of water was added and well stirred, and then about 1N hydrogen chloride solution was added to adjust to PH5 and stirred for about 30 minutes. Continued. In this way, a precipitate in which the surface of magnesium hydroxide was coated with molybdenum oxide was obtained. The precipitate was separated by filtration, washed with water, and dried at 120 ° C for one day. The analysis value of molybdenum of this product was 0.3 wt%. 2. Magnesium hydroxide (2) Average particle size 0.8 micron (BET
2 kg of magnesium hydroxide having a specific surface area of 8 m ² / g) was uniformly suspended. Next, while stirring this suspension, a solution of 100 g of ammonium molybdate dissolved in 500 ml of water was added and well stirred, and then a hydrogen chloride solution of about 1N was added to adjust the pH to 5, and the stirring was continued for about 30 minutes. . In this way, a precipitate in which the surface of magnesium hydroxide was coated with molybdenum oxide was obtained. The precipitate was separated by filtration, washed with water, and dried at 120 ° C for one day. The analysis value of molybdenum of this product was 3.2 wt%. 3, Magnesium hydroxide (3) 10 liters of aqueous solution average particle size 0.8 micron (BET
2 kg of magnesium hydroxide having a specific surface area of 8 m ² / g) was uniformly suspended. Then, a solution of 100 g of thorium tetrachloride (reagent) dissolved in 500 ml of water was added to this suspension while stirring, and stirring was continued for about 30 minutes. In this way, a precipitate having thorium hydroxide coated on the surface of magnesium hydroxide was obtained. The precipitate is filtered off,
It was washed with water and dried at 120 ° C for one day. The analysis value of thorium of this product was 3.8 wt%. 4. Magnesium hydroxide (4) As magnesium hydroxide, average particle size is 11 microns (BE
T specific surface area of 4 m ² / g) (made by Asahi Glass kk, 200
-10) was used to carry out surface coating in the same manner as magnesium hydroxide (2). The analysis value of thorium of this product was 3.5 wt%. 5. Magnesium hydroxide (5) Magnesium hydroxide having an average particle size of 0.8 micron (BET specific surface area 8 m ² / g) without coating treatment.

Examples 1 and 2 Polypropylene resin (manufactured by Tosoh KK; J5100A, M)
FR 10, homopolymer), magnesium hydroxide (1) and antioxidant (manufactured by Yoshitomi Pharmaceutical KK; Yoshinox BHT) were added in the composition shown in Table 1, mixed with a Henschel mixer, and biaxially kneaded with a diameter of 30 mmφ. 2 in extruder
Extruded pellets were prepared at 20 ° C. Then, a test piece was prepared from the pellet with a 150-ton injection molding machine at a resin temperature of 230 ° C. and evaluated. The results are shown in Table 1. Both flame retardancy and whitening resistance were good.

Examples 3 and 4 Test pieces were prepared and evaluated in the same manner as in Examples 1 and 2 except that magnesium hydroxide (2) was used instead of magnesium hydroxide (1). The results are shown in Table 1. Both flame retardancy and whitening resistance were good.

Examples 5 and 6 Test pieces were prepared and evaluated in the same manner as in Examples 1 and 2 except that magnesium hydroxide (3) was used instead of magnesium hydroxide (1). The results are shown in Table 1. Both flame retardancy and whitening resistance were good.

Comparative Examples 1 and 2 Test pieces were prepared and evaluated in the same manner as in Examples 1 and 2 except that magnesium hydroxide (4) was used instead of magnesium hydroxide (1). The results are shown in Table 1. Inferior in flame retardancy.

Comparative Examples 3 and 4 Test pieces were prepared in the same manner as in Execution Order 1 and 2 except that magnesium hydroxide (5) which was not subjected to the coating treatment according to the present invention was used. evaluated. The results are shown in Table 1. Inferior in flame retardancy and whitening resistance.

Examples 7 and 8 Magnesium hydroxide (2) was tested in the same manner as in Examples 1 and 2 with an ethylene-vinyl acetate copolymer (Tosoh kk: Ultrasen 625) and the composition shown in Table 1. Pieces were prepared and evaluated. However, the kneading temperature was 175 ° C., and the injection temperature was 200 ° C. The results are shown in Table 1. Both flame retardancy and whitening resistance were good.

Comparative Examples 5 and 6 Test pieces were prepared in the same manner as in Examples 7 and 8 except that magnesium hydroxide (5) was not coated by the above method. evaluated. The results are shown in Table 1. Inferior in flame retardancy and whitening resistance.

[0030]

As is clear from the above description, the composition of the present invention is excellent in the flame retardant effect and the whitening resistance of the magnesium hydroxide flame retardant composition, which is expected as a halogen-free flame retardant composition. It is a composition.

[Table 1]

Claims (3)

[Claims] 1. Water comprising a polyolefin resin coated with 0.05 to 25 wt% of an oxide, hydroxide or carbonate of one or more metals selected from chromium, molybdenum, vanadium, thorium and cerium. A flame-retardant polyolefin resin composition comprising 30 to 75 wt% of magnesium oxide. 2. The flame-retardant polyolefin resin composition according to claim 1, wherein the coated magnesium hydroxide has a particle size of 3.0 μm or less. 3. The flame-retardant polyolefin composition according to claim 1, wherein the magnesium hydroxide to be coated has a BET specific surface area of 5 m ² / g or more.