JPH08134247A - Polyolefin flame-retardant foam composition - Google Patents

Abstract

(57) [Abstract] [Objective] The present invention is non-teratogenic, does not contain toxic external drugs, is safe, does not color during molding, and is unlikely to cause primary foaming.
An object is to provide a flame-retardant foam composition which is excellent in mass productivity during molding. [Structure] 100 parts by weight of polyolefin resin,
After molding a foamable composition comprising 1 to 50 parts by weight of ethylene bistetrabromophthalimide and 1 to 20 parts by weight of molybdenum trioxide, and a thermal decomposition type foaming agent, a viscosity reducing agent, an antioxidant, a stabilizer, etc., A foam composition obtained by heating and foaming.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a flame-retardant foam composition containing a polyolefin resin as a base material.

[0002]

2. Description of the Related Art Polyolefin flame-retardant foam compositions are used as interior materials for construction, interior materials for automobiles, and the like. As a method for producing a foam of a polyolefin resin, polyolefin resin and azodicarbonamide as a pyrolyzable foaming agent are blended, melt-kneaded and molded, and crosslinked by various radiations or by a chemical crosslinking agent and then crosslinked by heating. Methods for obtaining foams are known. A method of adding decabromodiphenyl oxide to a polyolefin-based resin in order to make a foam of the polyolefin-based resin flame-retardant is also well known. For example, JP-A-51-134762 discloses a method of adding decabromodiphenyl oxide or antimony trioxide as a flame retardant, and JP-A-51-146565 discloses a flame retardant agent. A method of adding decabromodiphenyl oxide, hexabromobenzene, or antimony trioxide as an agent is introduced. The reason why decabromodiphenyl oxide is used as a flame retardant for polyolefin resins is that it has the advantages of high flame retardancy, low cost, high heat resistance, etc. For this reason, the problem of producing toxic dioxin with teratogenicity has been pointed out, and regulations are becoming stronger. As an alternative to decabromodiphenyl oxide, there is tetrabromobisphenol A, but since it has low heat resistance, it is colored in a temperature range of 200 to 260 ° C. in which azodicarbonamide is thermally decomposed to generate a foaming gas. Therefore, as a flame retardant for polyolefin resin having no teratogenicity and high heat resistance, JP-A-2-73835 discloses ethylene bistetrabromophthalimide which is an aromatic bromine compound. Bistetrabromophthalimide contains 8 bromine atoms in the molecule,
The bromine content is about 70%, which is smaller than 80% or more of decabromodiphenyl oxide, and when added alone, the flame retardant effect is weaker than that of decabromodiphenyl oxide. In order to increase flame retardancy, it is well known to use antimony trioxide in combination with a halogen-based flame retardant, but antimony trioxide is designated as a non-medical deleterious substance by the deleterious substance and poison control method. There are environmental concerns about its use. On the other hand, in the method of using antimony trioxide in combination with a halogen-based flame retardant, primary foaming is likely to occur, and in order not to cause primary foaming, the molding temperature must be suppressed to a relatively low temperature,
There was a problem that productivity did not rise.

[0003]

SUMMARY OF THE INVENTION The present invention has been made in view of the above points, and is safe and difficult because it has no teratogenicity and does not include deleterious substances for medical use under the Deleterious Substances and Poison Control Law. It is an object of the present invention to provide a polyolefin resin flame-retardant foam composition that has excellent flammability, does not color during molding, and has excellent productivity.

[0004]

According to the present invention, a desired flame retardancy is obtained by adding 1 to 50 parts by weight of ethylenebispentabromophthalimide and 1 to 20 parts by weight of a molybdenum compound to 100 parts by weight of a polyolefin resin. It was completed by finding out that a foam composition can be obtained.

The present invention will be described in detail below. In the present invention, the polyolefin-based resin is a polymer or copolymer of olefinic hydrocarbons, such as polyethylene, polypropylene, ethylene such as ethylene-propylene copolymer, and α-olefins such as butene and pentene. Copolymer, ethylene-vinyl acetate copolymer, ethylene-acrylic acid copolymer, ethylene-acrylic acid ester copolymer, ethylene-styrene copolymer, ethylene-propylene-styrene-butadiene copolymer, ethylene-
It refers to a mixture of one to several kinds of resins selected from resins such as vinyl chloride copolymers. This may be partially modified such as a graft. Among the above, polyethylene and ethylene-vinyl acetate copolymer, which can be used at low temperature, are preferable.

As the thermal decomposition type foaming agent for foaming, a commonly used foaming agent is used, and azodicarbonamide is particularly preferable from the viewpoint of performance and price balance. Further, a physical foaming agent (organic gas, inorganic gas, water, etc.) can be used together. The addition amount of the thermal decomposition type foaming agent is 1 to 40 parts by weight with respect to 100 parts by weight of the resin component, and the addition amount is set within the range according to the desired expansion ratio. If it is less than 1 part, an effective foam will not be formed, and if it is more than 40 parts, it will be in an over-foamed state and a foam having no problem in appearance cannot be obtained.

The ethylene bispentabromophthalimide used in the present invention is an aromatic bromine compound, and the addition amount is 1 to 50 relative to 100 parts by weight of the polyolefin resin.
Used in parts by weight. If it is less than 1 part by weight, the flame retarding effect is insufficient, and if it is more than 50 parts by weight, the physical properties such as strength of the foam are impaired, which is not suitable. The molybdenum compound refers to a mixture of one or several kinds selected from molybdenum trioxide, molybdenum disulfide, ammonium decamolybdate, etc. Among them, the product does not cause coloring, and the content of molybdenum atoms per molecule is Molybdenum trioxide, which has a high flame retardant effect, is preferable. Addition of a molybdenum compound as a flame retardant aid synergistically enhances the flame retardant effect. The molybdenum compound is 1 to 2 with respect to 100 parts by weight of the polyolefin resin.
0 parts by weight are added. If the amount of the molybdenum compound is 1 part by weight or less, the flame retardancy-improving effect is not sufficiently exerted, and if it is 20 parts by weight or more, the physical properties such as strength of the foam are impaired and the moldability during foam molding is adversely affected. Absent. Molybdenum compounds are not designated as non-medical deleterious substances and have no teratogenicity.

The crosslinked structure of the polyolefin resin can be removed by using a chemical crosslinking agent, radiation or the like. In this case, a crosslinking accelerator may be used. As a crosslinking accelerator,
Polyfunctional monomers are mainly used, and tetraethylene glycol dimethacrylate, divinylbenzene, diallyl phthalate, triallyl isocyanurate, trimethylolpropane trimethacrylate, trimethylolpropane triacrylate and the like are preferably used. In addition to these, various additives used for ordinary blending such as a viscosity reducing agent such as low polymerization degree polybutene, other antioxidants, stabilizers and the like may be used if necessary.

A method for producing a foam will be described below. First,
The polyolefin resin and each composition are mixed by a mixer. The various compositions described above may be mixed in advance or separately supplied to the molding machine. The molding machine is not particularly limited, but a normal single-screw extruder, a twin-screw extruder or the like is preferably used. After being molded into a sheet, rod, etc. by a molding machine, it is heated in a heating furnace or the like to a temperature not lower than the decomposition temperature of the thermal decomposition type foaming agent to form a foam. When cross-linking is required, it can be cross-linked by irradiating a sheet, rod or the like with various kinds of radiation such as ionizing radiation or by activating a chemical cross-linking agent by heating or the like.
During or after cross-linking, a foam is formed by heating in a heating furnace or the like to a temperature not lower than the decomposition temperature of the pyrolytic foaming agent.

[0010]

[Function] Ethylene bis tetrabromophthalimide contains 8 bromine atoms in the molecule and has a bromine content of about 70%.
Since it is relatively high, it has good flame retardancy. Melting point 3
It is as high as 00 ° C or higher and does not melt even at the molding temperature and the foaming temperature, so that it does not bleed out to the surface. or,
Due to its high heat resistance, the foam is difficult to color. It is safe because it does not convert into a substance with teratogenicity. By adding a molybdenum compound as a flame retardant aid to ethylene bis-tetrabromophthalimide, it is possible to increase the flame retardancy that is insufficient when ethylene bis-tetrabromophthalimide is used alone. The molybdenum compound is not a non-medical deleterious substance and has relatively low toxicity. The reason why the molybdenum compound acts as a flame retardant aid for ethylenebistetrabromophthalimide is not clear, but because molybdenum has the action of inhibiting the flame by promoting the carbonization of the polyolefin, it also promotes the generation of hydrogen bromide. By doing so, it is presumed that hydrogen bromide and bromine gas are retained at the combustion site.

[0011]

The present invention will be described in more detail by the following examples. The present invention is not limited to the following examples. 1. Examples 1, 2, 3, 4 Melt index 2.0 g / 10 minutes, density 0.920
100 parts by weight of the polyethylene resin, 20 parts by weight of azodicarbonamide, 2.5 parts by weight of zinc stearate, and the parts by weight of ethylenebistetrabromophthalimide shown in Table 1 (SAYTEX BT manufactured by ALBEMARLE).
-93) and molybdenum trioxide were mixed and melt-kneaded by a plastograph. 3.0mm by hot pressing
Make a thick sheet, and the absorbed dose is 5.0 with an electron beam irradiation device.
Irradiate to Mrad, crosslink, then 210 ° C
Foamed in a heating oven. For the foam, the generation state of bubbles was visually observed. The uniform foams of Examples 1, 2, 3, and 4 were obtained. JIS K-for the above foam
The oxygen index was measured according to 7201. The larger the oxygen index, the higher the flame retardancy. The oxygen index of the polyethylene foam expanded without adding the flame retardant was about 18. Moreover, APHA was measured to examine the degree of coloring. APH
A is an evaluation index of color tone (coloring degree) by the American Public Health Association. The larger the value of APHA, the darker the color. APHA20 has the color of a white, normal foam,
APHA100 is brown. APHA of 30 or more is recognized as colored. The results are shown in Table 1. With the addition of 5 to 50 parts of ethylene bispentabromophthalimide to the addition of 2 to 18 parts of molybdenum trioxide, a foam having uniform cells can be obtained without impairing the moldability. It showed sufficient flame retardancy and was not colored.
In addition, this formulation system does not include non-medical deleterious substances.

2. Comparative Examples 1, 2, 3, 4 Melt index 2.0 g / 10 minutes, density 0.920
100 parts by weight of the polyethylene resin, 20 parts by weight of azodicarbonamide, 2.5 parts by weight of zinc stearate, and the parts by weight of ethylenebistetrabromophthalimide shown in Table 1 (SAYTEX BT manufactured by ALBEMARLE).
-93) and molybdenum trioxide were mixed and melt-kneaded by a plastograph. 3.0mm by hot pressing
Make a thick sheet, and the absorbed dose is 5.0 with an electron beam irradiation device.
Irradiate to Mrad, crosslink, then 210 ° C
Foamed in a heating oven. The foamed state was visually observed in detail for the generation state of bubbles. In Comparative Examples 1, 3 and 4, uniform foams were obtained, but in Comparative Example 2, foams with large gas release and uniform cells were not obtained. Comparative Example 1,
With respect to the foams 3 and 4, flame retardancy and coloring were evaluated in the same manner as in the examples. The results are shown in Table 1. Comparative Example 1 lacked in flame retardancy, and Comparative Examples 3 and 4 were colored.

3. Comparative Example 5 A sample was prepared and evaluated in the same manner as in Example 2 except that antimony trioxide was used instead of molybdenum trioxide.
The results are shown in Table 1. A foam having uniform cells was obtained, the foam exhibited flame retardance and was not colored. However, since this compounding system contains antimony trioxide, which is a non-medical deleterious substance, there is a problem in safety.

[0014]

[Table 1]

4. Example 5 Melt index 2.0 g / 10 minutes, density 0.920
100 parts by weight of polyethylene resin, 20 parts by weight of azodicarbonamide, 2.5 parts by weight of zinc stearate, ethylenebistetrabromophthalimide (ALBEMARL)
30 parts by weight of Saytex BT-93 manufactured by Company E) and 10 parts by weight of molybdenum trioxide were mixed and melt-kneaded by a plastograph. 3.0 on the heat press plate
A sheet having a thickness of mm was prepared, and the specific gravity before and after pressing was measured. The hot press conditions were such that the temperature holding time was changed every 30 seconds and the press plate temperature was set to 5 levels at intervals of several degrees for each holding time. 12
By the interpolation method, each temperature from 30 seconds to 210 seconds is set as the primary foaming point at a temperature at which the specific gravity decreases by 10% and the specific gravity becomes 0.95 with respect to the specific gravity after pressing at 0 ° C for 30 seconds of 1.05. The primary foaming point was determined for each holding time. Table 2 shows the results. 5. Comparative Example 6 A sample was prepared and evaluated in the same manner as in Example 5 except that antimony trioxide was used instead of molybdenum trioxide.
Table 2 shows the results. From Table 2, it can be seen that molybdenum trioxide has a higher primary foaming point than that of antimony trioxide, and primary foaming is less likely to occur.

[0016]

[Table 2]

[0017]

EFFECTS OF THE INVENTION According to the present invention, since a polyolefin resin is used in a predetermined mixing ratio with ethylenebistetrabromophthalimide as a flame retardant and a molybdenum compound as a flame retardant aid, it does not contain a teratogenic substance, Safe and
Since there is no coloring during molding and the primary foaming temperature is high, it is possible to obtain a flame-retardant foam composition having high productivity during molding and a high flame-retardant effect.

Claims (1)

[Claims] 1. A flame-retardant foam composition obtained by adding 1 to 50 parts by weight of ethylenebistetrabromophthalimide and 1 to 20 parts by weight of a molybdenum compound to 100 parts by weight of a polyolefin resin.