JPS5845459B2 - Self-extinguishing resin composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a self-extinguishing resin composition containing a large amount of magnesium hydroxide.

Specifically, the present invention relates to a self-extinguishing resin composition for injection molding, which is made by blending magnesium hydroxide with polyolefin.

Conventionally, flame-retardant resins containing antimony oxide and halogen compounds have been known.

In this type of composition, antimony halides are produced by heating during combustion.

This antimony halide is a heavy gas, which is thought to give it self-extinguishing properties.

However, antimony oxide and many halogen compounds are toxic to the human body, and the use of self-extinguishing compositions of this type creates the risk of toxic gases in the event of a fire.

On the other hand, it is known that flame-retardant plastics can be obtained by blending a large amount of fine powder such as aluminum hydroxide with polyolefin.

However, the blending of aluminum hydroxide is good when the melting point of the polyolefin is extremely low, but when the melting point is somewhat high, such as polypropylene or high-density polyethylene, the thermal decomposition of aluminum hydroxide occurs at 200°C, which is close to the melting point of the polyolefin. Since the process starts from the vicinity, dehydration and foaming phenomena occur during the wiring and molding process, which has the disadvantage that a molded product with practical performance cannot be obtained.

The present inventors previously investigated various hydroxides and hydrated compounds as inorganic compounds that thermally decompose and generate moisture during heating in place of aluminum hydroxide, and found that only magnesium hydroxide It has been found that it is possible to impart desired flame retardancy without causing foaming during kneading and molding.

This means that most hydroxides and hydrates are
At a temperature of 250°C, moisture begins to be generated due to thermal decomposition.
While dehydration and foaming phenomena occur during blend molding of polyolefin, magnesium hydroxide alone
Moisture is generated only after reaching a certain high temperature, and
This is presumed to be because the generation of moisture is completed near the decomposition temperature of polyolefin, which is 350° C., and thus the generated moisture efficiently contributes to preventing combustion of polyolefin.

Polyolefin compositions containing magnesium hydroxide tend to produce silver streaks during injection molding, and
Molded products have the disadvantage of not having sufficiently high impact resistance.

Furthermore, there is a drawback that the melt index becomes significantly high.

An object of the present invention is to prevent the occurrence of silver streaks during injection molding, which are caused by blending magnesium hydroxide, and to improve impact resistance.

The present invention aims to achieve the above object, and comprises polypropylene, polyethylene or crystalline ethylene-propylene copolymer of 60 to 6% by weight, magnesium hydroxide of 35 to 80% by weight, and ethylene content of 20 to 85% by weight. 5 to 1 rubbery ethylene-propylene random copolymer with a Mooney viscosity of 20 to 150 ML1+4 (100°C)
The present invention provides a flame-retardant polyolefin composition characterized in that it contains 4% by weight.

Furthermore, in order to achieve the purpose of improving the melt index, 1 to 6% by weight of fatty acid metal salt is blended with respect to magnesium hydroxide.

The polypropylene, polyethylene, and crystalline ethylene-propylene copolymer used in the present invention may be those used in the production of ordinary polyolefin composition molded articles, and as the polyethylene, either low-density polyethylene or high-density polyethylene may be used. .

In particular, (1) the melt index at 230°C and a load of 2.16 kg is l'/lo min or more in the case of polypropylene or crystalline propylene ethylene copolymer;

@ In the case of high-density polyethylene or crystalline ethylene-propylene copolymer, the tart index at 190°C and a load of 2.16 kg is preferably 2 g/10 minutes or more.

Antioxidants are usually added to polyolefins.

As the antioxidant, any of commonly used phenolic antioxidants, phosphorus antioxidants, sulfur antioxidants, etc. may be used.

The magnesium hydroxide used in the present invention preferably has an average particle size of 0.1 .mu.m to 1.5 .mu.m.

The rubbery ethylene-propylene random copolymer used in the present invention has an ethylene (C2) content of 20 to 85% by weight,
Preferably 70-85% by weight, Mooney viscosity 20-15
0ML1+4 (100'C) preferably 40-120M
L1+4 (100°C).

In the present invention, it is particularly advantageous to incorporate fatty acid metal salts, particularly metal salts of aluminum, zinc, magnesium, calcium, etc. of fatty acids having 8 to 20 carbon atoms, since the tart index can be improved. Its blending amount is 1 to 6% by weight based on magnesium hydroxide.
, preferably 2 to 3.5% by weight.

In addition, calcium carbonate, zeolite, clay, talc,
A small amount of desired inorganic filler such as silica, asbestos, glass fiber, mica, etc. can be blended.

Magnesium hydroxide or other inorganic fillers can be used after surface modification as desired.

This zero surface modification method involves
Alternatively, the surface may be modified using polymers such as monomers such as stearic acid, oleic acid, caprylic acid, lauric acid, acrylic acid, and acrylic acid derivatives, and polymers of polyacrylic acid and acrylic acid derivatives.

The surface modification treatment method is to perform a desired modification treatment such as a chemical reaction method, a surface polymerization method, a mechanochemical method, etc.0. % by weight gives particularly good physical properties.

That is, an organic cellulose filler such as wood flour and a carbon number of 8 to 2.
The specific synergistic effect of the 0 fatty acids with metal salts such as aluminum, zinc, magnesium or calcium gives the formulation increased impact strength without loss of flowability.

Regarding the blending ratio of magnesium hydroxide, according to the measurement method according to the combustion test method ASTM D-635, it is 45 ~
55% by weight is a self-extinguishing region, 55 to 80% by weight is a non-flammable region, and above 80% by weight it is impossible to mold.

As a kneading method for obtaining the composition of the present invention, a usual melt kneading method using a roll, a Banbury mixer 1 single screw extruder, a twin screw extruder, etc. is used.

It is desirable that the temperature of the cross-wire be carried out in a temperature range from the melting point of the polyolefin to 300°C.

Example 1 Crystalline ethylene-propylene copolymer (MI=4, (B
i'/10 minutes) 33% by weight, 55% by weight of magnesium hydroxide with an average particle size of 1μ, and 12% by weight of rubbery ethylene propylene random copolymer (C2 content 74% by weight, Mooney viscosity 70ML1+4 (100°C)) and stable. (3% by weight of calcium stearate based on magnesium hydroxide) by stirring with a mixer for 5 minutes,
Further, the mixture was kneaded and granulated using a high-kneading extruder (temperature set at 260°C).

Next, using a screw in-line (non-ben-D injection molding machine (molding temperature 250 to 270°C)), flame retardant test pieces (127 zi x 12.7 zi (300mrn×300ziX 150mrn) was manufactured.

Table 1 shows the test results for flame retardancy, appearance evaluation, and physical properties of the test piece and molded product.

Flame retardancy was tested according to UL Standard 94.

Impact resistance is determined by Izot according to JISK-7110.
Dinstat was also tested using B5-1.330.

Example 2 Low density polyethylene (MI = 4.5, !li'/
10 minutes) 33% by weight and 55% by weight of magnesium hydroxide (stearic acid surface treated product) with an average particle size of 1μ and Example 1
12% by weight of the same rubbery ethylene-propylene random copolymer used in and a stabilizer (3% by weight of calcium stearate relative to magnesium hydroxide) were mixed by stirring in a mixer for 5 minutes, and The mixture was kneaded and granulated using a high-kneading extruder (temperature set at 260°C).

Table 1 shows the results of molding and testing in the same manner as in Example 1.

Comparative Example 1 45% by weight of the same crystalline ethylene-propylene copolymer used in Example 1, 55% by weight of magnesium hydroxide with an average particle size of 1μ, and a stabilizer (3% by weight of calcium stearate relative to magnesium hydroxide) %), granulation, molding, and testing were performed in the same manner as in Example 1.

The results are shown in Table 1.

Comparative Example 2 45% by weight of the same low-density polyethylene used in Example 2, 55% by weight of magnesium hydroxide (stearic acid surface treated product) with an average particle size of 1μ, and a stabilizer (calcium stearate was added to magnesium hydroxide). Granulation, molding, and testing were performed in the same manner as in Example 1 using 3% by weight).

The results are shown in Table 1.

Claims (1)

[Claims] 1 Polypropylene, polyethylene or crystalline ethylene-propylene copolymer 60-6% by weight, magnesium hydroxide 35-80% by weight, ethylene content 20-85% by weight, Mooney viscosity 20-150 ML1+4 (100
A flame-retardant polyolefin composition characterized in that it contains 5 to 14% by weight of the rubbery ethylene-propylene random copolymer of 0C). 2. The flame-retardant polyolefin composition according to item 1, which contains 1 to 6% by weight of a fatty acid metal salt based on magnesium hydroxide.