JP3315620B2 - Olefin resin foam - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an olefin resin foam having excellent flame retardancy.

[0002]

2. Description of the Related Art Olefin-based resin foams have excellent heat insulation properties, and are widely used in building materials, interior materials for transportation equipment such as automobiles, sound and vibration proof materials, heat insulation materials for electric appliances, packaging materials, household goods, and the like. It's being used. Further, when used for the above applications, flame retardancy is often required, and a halogen-containing compound is generally added to improve the flame retardancy.
A foam to which a halogen-containing compound is added is excellent in flame retardancy, and has a feature that the addition of the halogen-containing compound does not cause a decrease in molding processability or mechanical strength. There has been a problem that the added amount becomes large and physical properties such as elongation are reduced.

In JP-A-51-146565, a foam having excellent flame retardancy is obtained by adding antimony trioxide in addition to a halogen-containing compound to an ethylene resin. However, antimony trioxide improves the flame retardancy and promotes the decomposition of the foaming agent more than necessary, so the range of the degree of crosslinking of the resin component suitable for foaming is narrow, and foaming is more difficult than ethylene-based resin. When a certain propylene-based resin is used, there are problems that abnormal cells such as giant cells are generated to deteriorate the appearance of the foam, and that a foam having a high expansion ratio cannot be obtained.

[0004]

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

[0005]

The olefin resin foam of the present invention has an elution amount of 75 to 90% by weight at 94 ° C. or higher, 60 to 75% by weight at 100 ° C. or higher, by a cross fractionation method.
In addition, the melt index (hereinafter referred to as MI) is 0.
2 to 5 g / 10 min propylene resin 30 to 90% by weight
And 100 to 100 parts by weight of an olefin resin comprising 10 to 70% by weight of an ethylene resin, 1 to 100 parts by weight of a bromine-containing compound, and 0.1 to 10 parts by weight of antimony trioxide.

The propylene resin used in the present invention is:
A propylene homopolymer or propylene having a main component of propylene homopolymer or propylene having an elution amount of 75 to 90 wt% at 94 ° C or higher, 60 to 75 wt% at 100 ° C or higher, and an MI of 0.2 to 5 g / 10 min. Copolymers with other monomers, which may be used alone or in combination of two or more. As a copolymer with another monomer containing propylene as a main component, for example, the propylene content is 85% by weight.
Examples of the above propylene-α-olefin copolymer include α-olefins, for example, ethylene, 1-
Butene, 1-pentene, 1-hexene, 4-methyl-1
-Pentene, 1-heptene, 1-octene and the like.

[0007] The amount of the propylene resin eluted by the cross fractionation method decreases as the heat resistance of the obtained foam decreases, and as the amount increases, the flexibility of the obtained foam decreases. At 94 ° C. or higher, since the dispersibility of the additives tends to deteriorate, and the desired expansion ratio cannot be obtained or the appearance tends to deteriorate.
-90% by weight, and 60-75% by weight at 100 ° C or higher
Is limited to

The cross fractionation method referred to in the present invention is a method described below. First, the propylene-based resin is dissolved in o-dichlorobenzene at 140 ° C. or at a temperature at which the propylene-based resin is completely dissolved, and then cooled at a constant rate. It is formed as a thin polymer layer in the descending order. Next, the concentration of the components eluted sequentially by increasing the temperature continuously or stepwise is detected,
Measure composition distribution or crystallinity distribution. This is referred to as temperature rise elution fractionation. In the present invention, a cross-separation chromatograph (trade name “CFC”, manufactured by Mitsubishi Chemical Corporation) having the above-mentioned temperature rising elution fractionation and high-temperature type GPC part as a system
-T150A type ").

The propylene resin has an MI of JI
It is a value measured in accordance with SK7210. If the value is small, extrusion molding is difficult, and if the value is large, the heat resistance of the obtained foam is reduced. Therefore, the value is limited to 0.2 to 5 g / 10 minutes, and preferably 0 to 5 g / 10 minutes. 0.5 to 3 g / 10 min.

The ethylene resin used in the present invention is an ethylene homopolymer or a copolymer with another monomer containing ethylene as a main component, and these may be used alone or in combination of two or more. Is also good. Examples of the copolymer with another monomer containing ethylene as a main component include, for example, an ethylene-α-olefin copolymer, an ethylene-vinyl acetate copolymer, and an ethylene-ethyl acrylate copolymer having an ethylene content of 80% by weight or more. Examples of the α-olefin include propylene, 1-butene, 1-pentene, 1-hexene, 4-methyl-1-pentene and 1-olefin.
Heptene, 1-octene and the like.

The olefin resin used in the present invention comprises:
Consisting of the above propylene-based resin and ethylene-based resin, the blending amount of the propylene-based resin is reduced, the heat resistance of the obtained foam is reduced, the melt viscosity of the resin component is increased when the amount is increased, the appearance of the obtained foam is Because it gets worse, 3
It is limited to 0 to 90% 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, , 2-bispentabromophenylethane, hexabromocyclododecane, tetrabromobisphenol A, etc., which 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 is not improved, and when the addition amount is large, the flame retardancy effect is not improved to a certain degree or more, and the foaming characteristics of the resin component are reduced.
The amount is limited to 1 to 100 parts by weight, and preferably 2 to 30 parts by weight.

The antimony trioxide used in the present invention is:
It is intended to improve the flame retardancy of the foam obtained by using it in combination with the bromine-containing compound, and has an average particle size of preferably 1 μm or less, more preferably 0.5 μm.
It is as follows. When the amount of added antimony trioxide is small, the flame retardancy is reduced, and when the amount is large, antimony trioxide promotes the decomposition of the blowing agent more than necessary, causing problems such as generation of giant air bubbles, and appearance of the obtained foam. Becomes worse,
0.1 to 1 with respect to 100 parts by weight of the olefin resin
It is limited to 0 parts by weight, preferably 1 to 5 parts by weight.

The ratio of the addition of the bromine-containing compound to the antimony trioxide is preferably 1: 1 to 4: 1 by weight, since the effect of improving the flame retardancy is increased.

On the other hand, if the amount of the propylene resin in the olefin resin exceeds 70% by weight, the dispersibility of the bromine-containing compound and antimony trioxide decreases, and the flame retardancy is hardly exhibited. The olefin resin 10
It is preferable to add 5 parts by weight or more of the bromine-containing compound and 2 parts by weight or more of antimony trioxide to 0 part by weight.

As the method for obtaining the olefin resin foam of the present invention, any conventionally known method may be employed. For example, a pyrolyzable foaming agent is added to the olefin resin, the bromine-containing compound and antimony trioxide. And a twin-screw extruder,
After melt-kneading at a temperature lower than the decomposition temperature of the pyrolytic foaming agent in a kneading device such as a Banbury mixer, kneader mixer, roll, etc., it is generally formed into a sheet, irradiated with ionizing radiation, crosslinked, and then subjected to thermal decomposition. A method of foaming by heating to a temperature higher than the decomposition temperature of the foaming agent may be used.

The thermal decomposition type foaming agent generates a decomposition gas by heating, and examples thereof include azodicarbonamide, benzenesulfonylhydrazide, dinitrosopentamethylenetetramine, 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 generally 1 to 5
0 parts by weight, preferably 4 to 25 parts by weight, adjusted according to the desired expansion ratio.

The ionizing radiation includes, for example, α
Radiation, β-ray, γ-ray, electron beam and the like, and the irradiation amount is not particularly limited, but is generally 1 to 20 Mrad.

It is preferable to add a polyfunctional monomer or a monofunctional monomer in advance in order to promote the crosslinking by irradiation with the ionizing radiation. Polyfunctional monomers and monofunctional monomers are those commonly used and include, for example, divinylbenzene, trimethylolpropane trimethacrylate, 1,9-nonanediol dimethacrylate, 1,10-decanediol dimethacrylate, trimellit. Acid triallyl ester, triallyl isocyanurate, ethylvinylbenzene, neopentyl glycol dimethacrylate, 1,2,4-benzenetricarboxylic acid triallyl ester, 1,6-hexanediol dimethacrylate, lauryl methacrylate, stearyl methacrylate, and the like. These may be used alone or in combination of two or more. If the addition amount of the polyfunctional monomer and the monofunctional monomer is too small, a desired degree of crosslinking cannot be obtained, and if the amount is too large, the control of the degree of crosslinking becomes difficult, and the appearance of the obtained foam deteriorates. 0.5 to 10 parts by weight per 100 parts by weight is preferred.

As the above-mentioned heating method, any conventionally known method may be adopted, for example, a method of exposing to hot air, infrared rays, etc., a method of immersing in an oil bath, a metal bath or the like.

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

[0022]

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.

In Examples and Comparative Examples, propylene resin (PP) and ethylene resin (LLDP) shown below were used.
E) was used. PP1; 81 eluted by cross fractionation at 94 ° C or higher
% By weight, 64.4% by weight at 100 ° C. or higher, MI: 2.2
g / 10 min propylene homopolymer PP2;
Propylene homopolymer PP3: 4.4% by weight, 72.2% by weight at 100 ° C. or more, MI: 0.5 g / 10 min;
1.7% by weight, 63.8% by weight at 100 ° C. or higher, propylene homopolymer PP4 having an MI of 2 g / 10 minutes;
3.5% by weight, 30% by weight above 100 ° C., MI: 1.
8 g / 10 min propylene homopolymer PP5;
% By weight, 65% by weight at 100 ° C. or higher, MI: 12 g / 1
0 minute propylene homopolymer

LLDPE1; linear low-density polyethylene L-LDPE2 copolymerized with 8% by weight of 1-octene having an MI of 2 g / 10 min and a density of 0.915 g / cm ³ ; LLDPE2; 920
g / cm ³ 1-octene is copolymerized with 8% by weight of linear low density polyethylene LLDPE3; MI is 8 g / 10 min, density is 0.920
g / cm ³ linear low-density polyethylene copolymerized with 8% by weight of 1-octene

[0025]

【Example】

(Examples 1 to 6, Comparative Examples 1 to 6) Predetermined amounts of PP1 to 5, LLDPE1 to 3, decabromodiphenyl oxide, hexabromobenzene, 1,2-bispentabromophenylethane, and average particles shown in Table 1 0.5 μm diameter antimony trioxide, trimethylolpropane trimethacrylate, divinylbenzene, azodicarbonamide, 2,6
-Di-t-butyl-p-cresol, dilaurylthiopropionate and methylbenzotriazole are melt-kneaded at 190 ° C by a twin-screw extruder and then extruded to a thickness of 1 mm.
Into a continuous sheet. 700 in the obtained continuous sheet
After irradiating both sides with an electron beam of kv at a rate of 3 Mrad, cross-linking was performed, followed by foaming in a 250 ° C. foaming furnace to obtain a foam. The degree of crosslinking and the expansion ratio of the obtained foam were as shown in Table 1.

In the present invention, the degree of crosslinking and the expansion ratio are values measured by the following methods. (Degree of Crosslinking) First, about 100 mg of the foam was weighed, and the value was defined as the dry weight before extraction. Next, crush the foam cells,
It was immersed in 50 ml of xylene at a temperature of 120 ° C., allowed to stand for 24 hours, extracted, filtered through a 200-mesh stainless steel wire gauze, dried on the wire gauze, weighed, and the value was taken as the dry weight of the residue. did. The degree of crosslinking was calculated from the dry weight before extraction and the dry weight of the residue by the following formula. Degree of crosslinking (%) = (dry weight of residue / dry weight before extraction) × 100

(Expansion ratio) This is the reciprocal of the density of the foam measured by an electronic hydrometer (trade name “ED120T” manufactured by Mirage Co., Ltd.).

The foam obtained was evaluated for flame retardancy, moldability and appearance as follows. (Evaluation of Flame Retardancy) A flammability test was performed in accordance with JIS D 1201, and the flammability classification is shown in Table 1.

(Evaluation of molding workability) Both sides of foam were 18
Heated to 0 ° C, vacuum formed with a cylindrical concave mold having a diameter of 100 mm and a forming draw ratio (depth / diameter) of 0.8. The case where the body was torn was evaluated as x, and the results are shown in Table 1.

(Evaluation of Appearance) The surface of the foam was visually observed, and 場合 indicates that no appearance defect such as uneven foaming was observed, and X indicates that the appearance defect was observed. 1 is shown.

[0031]

[Table 1]

[0032]

The olefin resin foam of the present invention has excellent flame retardancy, uniform cells and good appearance, and is excellent in heat resistance, flexibility and toughness. In this case, the surface can be formed into a deep concave without roughening, and the molding processability is excellent.

Claims (1)

(57) [Claims] 1. A propylene-based resin 30 having an elution amount of 75 to 90% by weight at 94 ° C. or higher, 60 to 75% by weight at 100 ° C. or higher, and a melt index of 0.2 to 5 g / 10 min. An olefin-based resin foam comprising 100 parts by weight of an olefin-based resin comprising from 90 to 90% by weight and 10 to 70% by weight of an ethylene-based resin, 1 to 100 parts by weight of a bromine-containing compound, and 0.1 to 10 parts by weight of antimony trioxide.