JPH10204200A - Olefin resin foam - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a foam having excellent flame retardancy and vacuum forming properties and good appearance by using a composition comprising a specified amount of an olefin resin comprising a propylene resin and an ethylenic resin in a specified ratio, a specified amount of a bromine compound and a specified amount of antimony trioxide having a specified or smaller mean particle diameter. SOLUTION: A composition comprising 100 pts.wt. olefin resin comprising 30-90wt.% propylenic resin and 70-10wt.% ethylenic resin, 1-100 pts.wt. bromine compound and 0.1-10 pts.wt. antimony trioxide having a mean particle diameter of 0.4μm or below is crosslinked and foamed. The propylenic resin used is a polypropylene or a copolymer of a major proportion of propylene with another monomer each of which is usually used in the production of foams. The ethylenic resin used is a polyethylene or a copolymer of a major proportion of ethylene with another monomer each of which is usually used in the production of foams. The bromine compound used is desirably one containing at least 40wt.% bromine in the molecule.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an olefin resin foam.

[0002]

2. Description of the Related Art An olefin resin foam is excellent in flexibility and heat insulating property, and is generally formed into a desired shape by vacuum forming, and is used for building materials, interior materials for transportation equipment such as automobiles, and heat insulation for electric appliances. Widely used for materials, packaging materials, household goods, etc. When used for the above applications, flame retardancy is often required, and in order to improve flame retardancy, a halogen-containing compound is generally added to the foam. A foam to which a halogen-containing compound has been added is characterized by having excellent flame retardancy and little decrease in moldability and mechanical strength. However, when a halogen-containing compound is used alone, there is a problem that the amount of the compound to be added becomes large and physical properties such as elongation are reduced. Therefore, Japanese Patent Application Laid-Open No. 51-1465
In Patent Publication No. 65, a halogen-containing compound and antimony trioxide are added to an ethylene resin to obtain a foam having excellent flame retardancy. However, since antimony trioxide has the effect of improving the flame retardancy and promoting the decomposition of the blowing agent,
The range of the degree of crosslinking suitable for foaming is narrow, and when using a propylene-based resin that is difficult to foam as compared with an ethylene-based resin, abnormal bubbles such as giant bubbles are generated and the appearance of the foam is reduced, Further, there is a problem that a foam having a high expansion ratio cannot be obtained, and vacuum formability is reduced.

[0003]

SUMMARY OF THE INVENTION An object of the present invention is to provide an olefin resin foam having excellent flame retardancy and vacuum moldability and good appearance.

The olefin resin foam of the present invention comprises 30 to 90% by weight of propylene resin and 70% of ethylene resin.
100 parts by weight of an olefin-based resin consisting of
The bromine-containing compound has a content of 1 to 100 parts by weight and an average particle size of 0.
It is characterized by comprising 0.1 to 10 parts by weight of antimony trioxide of 4 μm or less.

The olefin resin used in the present invention is:
It consists of a propylene resin and an ethylene resin.

[0006] The propylene resin is a copolymer of polypropylene and other monomers containing propylene as a main component, which are generally used in the production of foams, and they may be used alone or in combination of two or more. The copolymer may be any of a random copolymer, a block copolymer, and a random block copolymer. Examples of the copolymer include a propylene-α-olefin copolymer containing 85% by weight or more of propylene, and examples of the α-olefin include ethylene, 1-butene, 1-pentene, 1-hexene, -Methyl-1-pentene, 1
-Heptene, 1-octene and the like.

When the melt index (hereinafter referred to as MI) of the propylene-based resin is small, it becomes difficult to extrude the resin component, and when it is large, the heat resistance of the foam tends to decrease. Min, more preferably 0.5 to 3 g / 10 min. MI in the present invention is a value measured in accordance with JIS K7210.

When the weight-average molecular weight of the propylene-based resin decreases, the heat resistance of the foam decreases, so that the appearance of the foam deteriorates due to breakage of bubbles at the time of secondary processing or the like. 2 × 10 ⁵ to 10 × 10 ⁵ is preferable, since productivity tends to decrease due to decrease in productivity.

The above-mentioned ethylene resin is a copolymer of polyethylene and other monomers containing ethylene as a main component, which are generally used in the production of foams, and these may be used alone or in combination of two or more. May be done. Examples of the copolymer include an ethylene-α-olefin copolymer containing 80% by weight or more of ethylene, an ethylene-vinyl acetate copolymer, an ethylene-ethyl acrylate copolymer, and the like. For example, propylene, 1-butene, 1-pentene, 1-hexene, 4-
Methyl-1-pentene, 1-heptene, 1-octene and the like can be mentioned.

[0010] The MI of the ethylene resin is preferably 0.5 to 5 g / 10 minutes, because the smaller the MI, the more difficult it is to extrude the resin component, and the larger the MI, the lower the heat resistance of the foam.

When the amount of the propylene resin is too small, the heat resistance of the foam decreases, and when the amount is too large, the melt viscosity of the resin component becomes large, so that extrusion becomes difficult and the appearance of the foam deteriorates. Since the body does not tend to have a high expansion ratio, the amount is 30 to 90% by weight, and the blending amount of the ethylene resin is 70 to 10% by weight.

The bromine-containing compound used in the present invention preferably contains at least 40% by weight of bromine atoms in the molecule. Examples of such a bromine-containing compound include tetrabromobenzene, pentabromobenzene and hexabromobenzene. Bromobenzene, hexabromobiphenyl ether, tribromophenol, tetrabromophthalic anhydride, hexabromocyclododecane, decabromodiphenyl oxide, tetradecabromophenoxybenzene, ethylenebistetrabromophthalimide, 1,2-bistetrabromophenylethane, hexa Bromocyclododecane, tetrabromobisphenol A and the like can be mentioned, and these may be used alone or in combination of two or more. When the addition amount of the bromine-containing compound is small, the flame retardancy of the foam is not improved, and when it is large, the effect of the flame retardancy is not improved to some extent,
Also, since the foaming properties of the resin component tend to decrease,
It is 1 to 100 parts by weight, preferably 2 to 30 parts by weight, based on 100 parts by weight of the olefin resin.

The antimony trioxide used in the present invention is:
It is intended to improve the flame retardancy of the foam by being used in combination with the bromine-containing compound, and the average particle size thereof is 0.4 μm since the flame retardancy tends to decrease as the size increases.
m, preferably 0.3 μm or less. When the amount of antimony trioxide is reduced, the flame retardancy is reduced, and when the amount is increased, antimony trioxide promotes the decomposition of the blowing agent more than necessary, causing problems such as generation of giant air bubbles, and the appearance of the foam is reduced. Since it tends to worsen, the amount is 0.1 to 10 parts by weight, preferably 0.5 to 6 parts by weight, more preferably 1 to 100 parts by weight based on 100 parts by weight of the olefin resin.
-5 parts by weight.

The relationship between the amount of the bromine-containing compound and the amount of antimony trioxide added is that the bromine-containing compound is added in an amount of 1 to 4 times the weight of antimony trioxide in terms of improving flame retardancy. Is preferred.

The olefin resin foam of the present invention is obtained by crosslinking and foaming a resin composition comprising the above olefin resin, a bromine-containing compound and antimony trioxide. May be adopted,
For example, a pyrolytic foaming agent, a crosslinking assistant, etc. are added to the olefin resin, the bromine-containing compound and antimony trioxide, and the mixture is thermally decomposed by a kneading device such as a twin-screw extruder, a Banbury mixer, a kneader mixer, or a roll. Melt and kneaded at a temperature lower than the decomposition temperature of the foaming agent, usually formed into a sheet, irradiated with ionizing radiation to crosslink the resulting sheet, and then foamed by heating to a temperature equal to or higher than the decomposition temperature of the thermal decomposition foaming agent. Method.

The above-mentioned pyrolytic foaming agent generates a decomposed gas by heating, and examples thereof include asodicarbonamide, benzenesulfonylhydrazide, dinitropentamethylenetetramine, and toluenesulfonylhydrazide. These can be used alone. Or two or more of them may be used in combination. The amount of the pyrolytic foaming agent is adjusted according to the desired expansion ratio, and is generally 1 to 50 parts by weight, preferably 4 to 25 parts by weight.

The crosslinking aid promotes crosslinking by irradiation with ionizing radiation, and is a generally used polyfunctional monomer or monofunctional monomer, for example, divinylbenzene, trimethylolpropane trimethacrylate, 1,9-nonanediol dimethacrylate, 1,
10-decanediol dimethacrylate, triallylic acid triallyl ester, triallyl isocyanurate,
Ethyl vinyl benzene, neopentyl glycol dimethacrylate, 1,2,4-benzenetricarboxylic acid triallyl ester, 1,6-hexanediol dimethacrylate, lauryl methacrylate, stearyl methacrylate, etc., which may be used alone Two or more kinds may be used in combination. Since the desired amount of crosslinking agent cannot be obtained when the amount of the crosslinking aid is reduced, and when the amount is increased, the control of the degree of crosslinking becomes difficult, and the appearance of the foam tends to deteriorate.
0.5 to 10 based on 100 parts by weight of the olefin resin
Parts by weight are preferred.

The ionizing radiation includes, for example, α
Ray, β ray, γ ray, electron beam and the like. The dose of ionizing radiation is not particularly limited, but is generally 1 to 20 M
rad.

The olefin-based resin foam of the present invention may have 2,6-di-t-
Various types of phenols such as butyl-p-cresol, sulfur-based such as dilaurylthiopropionate, antioxidants such as phosphorus-based and amine-based, metal hazard inhibitors such as methylbenzotriazole, heat stabilizers, pigments, etc. Additives may be added.

[0020]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The embodiments of the present invention will be described in more detail with reference to the following examples, but the present invention is not limited to these examples.

Hereinafter, the following compounds were used. PP1; melt index = 2.2 g / 10 min, weight
Average molecular weight = 3.4 × 10^FivePolypropylene PP2; melt index = 2 g / 10 min, weight average
Molecular weight = 3.8 × 10 ^FivePolypropylene LLDPE1; MI = 2 g / 10 min, density = 0.915
g / cm^ThreeOf 1-octene was copolymerized by 8% by weight
Linear low density polyethylene LLDPE2; MI = 4 g / 10 min, density = 0.920
g / cm^ThreeOf 1-octene was copolymerized by 8% by weight
Chain low density polyethylene

【Example】

(Example 1) 50 parts by weight of PP1 and 50 parts of LLDPE1
Parts by weight, 10 parts by weight of decabromodiphenyl oxide, 2 parts by weight of antimony trioxide having an average particle size of 0.25 μm, and 2 parts by weight of trimethylolpropane trimethacrylate.
Asodicarbonamide 1 is added to a resin composition consisting of parts by weight.
0 parts by weight, 0.3 parts by weight of 2,6-di-t-butyl-p-cresol, 0.3 parts by weight of dilaurylthiopropionate and 0.5 parts by weight of methylbenzotriazole were added, and biaxial After melt-kneading at 190 ° C. in an extruder, it was formed into a continuous sheet having a thickness of 1 mm. An electron beam having an acceleration voltage of 700 kv was applied to both sides of the obtained continuous sheet for a total of 3.0 Mr.
After ad irradiation and crosslinking, the foam was continuously foamed in a vertical hot-air foaming furnace maintained at 250 ° C. by hot air and an infrared heater to obtain a foam. The degree of crosslinking of the foam was 35%, and the expansion ratio was 25 cc / g.

Example 2 A resin composition was prepared by adding PP1 to 60
Example 1 Example 1 was changed except that LLDPE1 was 40 parts by weight, decabromodiphenyl oxide was 6 parts by weight, antimony trioxide having an average particle diameter of 0.3 μm was 6 parts by weight, and divinylbenzene was 3 parts by weight. In the same way as
A foam was obtained. The degree of crosslinking of the foam was 40.5%, and the expansion ratio was 20 cc / g.

Example 3 A resin composition containing PP1 was 70
Parts by weight, 30 parts by weight of LLDPE2, 6 parts by weight of hexabromobenzene, 4 parts by weight of antimony trioxide having an average particle diameter of 0.3 μm, and 2.5 parts by weight of trimethylolpropane trimethacrylate. In the same manner as in Example 1, a foam was obtained. The degree of crosslinking of the foam is 3
7%, and the expansion ratio was 22 cc / g.

(Comparative Example 1) A resin composition was prepared by adding PP1 to 50
Parts by weight, LLDPE1 was changed to 50 parts by weight, decabromodiphenyl oxide was changed to 10 parts by weight, antimony trioxide having an average particle diameter of 0.9 μm was changed to 2 parts by weight, and trimethylolpropane trimethacrylate was changed to 2 parts by weight. A foam was obtained in the same manner as in Example 1. The degree of crosslinking of the foam was 35%, and the expansion ratio was 19 cc / g.

(Comparative Example 2) A resin composition was prepared by adding PP1 to 60
Example 1 except that the parts were changed to those consisting of 40 parts by weight of LLDPE1, 6 parts by weight of decabromodiphenyl oxide, 6 parts by weight of antimony trioxide having an average particle diameter of 0.6 μm, and 3 parts by weight of divinylbenzene. In the same way as
A foam was obtained. The degree of crosslinking of the foam was 40.5%, and the expansion ratio was 16 cc / g.

(Comparative Example 3) A resin composition containing 95% PP2
Parts by weight, 5 parts by weight of LLDPE2, 6 parts by weight of hexabromobenzene, 4 parts by weight of antimony trioxide having an average particle diameter of 0.3 μm, and 2.5 parts by weight of trimethylolpropane trimethacrylate In the same manner as in Example 1, a foam was obtained. The degree of crosslinking of the foam is 37
%, And the expansion ratio was 5 cc / g.

The degree of crosslinking and the expansion ratio are values calculated by the following methods. About 100 mg of the degree of crosslinking foam is precisely weighed and its bubbles are crushed,
After being immersed in 50 mg of xylene at a temperature of 120 ° C. for 24 hours, the dry weight of the residue on the wire mesh when passing through a 200 mesh stainless steel wire mesh was measured, and the degree of crosslinking was calculated by the following equation. Degree of crosslinking (%) = (dry weight of residue / weight of weighed foam) × 100

Expansion ratio electronic densitometer (trade name "ED120", manufactured by Mirage Co., Ltd.)
T ") is the reciprocal of the density of the foam as measured using

The obtained foam was evaluated for flame retardancy, vacuum moldability, and appearance as described below.

(Flame retardancy) A flammability test was conducted in accordance with JIS D 1201, and the flammability classification is shown in Table 1.

(Vacuum Formability) The foam was heated to 180 ° C. on both sides and vacuum formed in a cylindrical concave mold having a diameter of 100 mm and a forming draw ratio (depth / diameter) of 0.8. The case where the foam was able to be molded without tearing was evaluated as ○, and the case where the foam was torn was evaluated as x, and the results are shown in Table 1.

(Appearance) The surface of the foam was visually observed, and ○ indicates that no appearance defect such as uneven foaming was observed, and X indicates that appearance defect was observed. Table 1 shows the results. It was shown to.

[0033]

[Table 1]

[0034]

As described above, the olefin resin foam of the present invention has excellent flame retardancy because it has the structure described above.
It has excellent heat resistance, flexibility and strength, so it does not have a rough surface even when processed at high temperatures, and can be processed into a deep molded product. It has a high foaming ratio and excellent vacuum moldability.

Claims (1)

[Claims] 1. An olefin resin comprising 30 to 90% by weight of a propylene resin and 70 to 10% by weight of an ethylene resin, 100 parts by weight of an olefin resin, 1 to 100 parts by weight of a bromine-containing compound, and a resin having an average particle diameter of 0.4 μm or less. Antimony oxide
An olefin resin foam comprising 1 to 10 parts by weight.