JP3320546B2 - Flame retardant polyolefin resin foaming composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a composition for foaming a flame-retardant polyolefin resin.

[0002]

2. Description of the Related Art Resin foams have excellent heat insulation properties and are widely used in building materials, transportation equipment such as automobiles, packaging materials, household goods, and the like. Among them, polyolefin-based resin foams are rich in chemical stability, have properties such as heat insulation, electrical insulation, and light weight, and are widely used as interior materials for automobiles and interior materials for buildings. I have.

[0003] However, with the expansion of use, it is required to impart flame retardancy to polyolefin resin foam which is inherently flammable, and flame retardation is performed by various methods.

As a method of making a polyolefin resin flame-retardant, a method of adding a halogen-containing compound is generally used. These can certainly impart a high degree of flame retardancy, and the decrease in molding processability and the decrease in mechanical strength of molded products are relatively small.However, large amounts of smoke and corrosive gas are generated during molding and combustion. This causes problems of corrosion of peripheral devices and harm to the human body. Particularly in recent years, in view of safety, there is a strong demand for flame retardancy without using a halogen-containing compound.

As a method of flame retardation, a method of flame retardation by adding a hydrated metal oxide which does not generate harmful gas during molding or burning of aluminum hydroxide, magnesium hydroxide, basic magnesium carbonate or the like. Japanese Patent Application Laid-Open No. 49-5
171 and JP-A-3-269029.

However, the method of adding a hydrated metal oxide requires a large amount of the hydrated metal oxide in order to impart sufficient flame retardancy to the polyolefin resin.
As a result, the mechanical strength of the molded article is reduced, and when used for foaming, the foamability is reduced, and it is difficult to obtain a foam having a fine closed cell structure.

JP-A-4-142348 and JP-A-4-142352 disclose a flame-retardant resin composition comprising ammonium polyphosphate, a nitrogen-containing compound and a petroleum resin with respect to a polyolefin resin. There is no description that it can be applied to a foaming resin composition.

[0008]

DISCLOSURE OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and has been made in view of the above problems, and is a foam having excellent flame retardancy, excellent foamability, and good appearance without uneven foaming. It is an object of the present invention to provide a flame-retardant polyolefin-based resin foaming composition for obtaining a resin.

[0009]

The polyolefin resin used in the present invention is preferably a polyethylene resin or a resin comprising a polyethylene resin and a polypropylene resin.

The polypropylene resin is not particularly limited, and may be a propylene homopolymer (polypropylene), a copolymer containing propylene as a main component, or a mixture thereof.

[0011] Examples of the copolymer include a propylene / α-olefin copolymer containing 85% by weight or more of propylene. Examples of the α-olefin include ethylene, 1-hexene, and 4-methyl-olefin. Examples thereof include 1-pentene, 1-octene, 1-butene, 1-pentene and the like.

The melt index (hereinafter referred to as "MI") used in the present invention is ASTM D1238.
It is a value measured in accordance with.

When the MI of the polypropylene-based resin is small, the moldability decreases, and when the MI is large, the heat resistance of the obtained foam is low. Therefore, the MI is 0.2 to 20 g / 10 min (hereinafter referred to as "g / 10 min"). Is abbreviated.), And more preferably 0.1 to 10.

The polyethylene resin may be an ethylene homopolymer (polyethylene), a copolymer containing ethylene as a main component, or a mixture thereof. Examples of the copolymer include an ethylene / α-olefin copolymer containing 80% by weight or more of ethylene. Examples of the α-olefin include 1-hexene, 4-methyl-1-pentene, and 1-octene. , 1-butene, 1-pentene and the like.

As the ethylene homopolymer, a low-density polyethylene having a long-chain branch is preferably used, and as the copolymer containing ethylene as a main component, a linear low-density polyethylene having a short-chain branch is preferably used.

Further, examples of the polyethylene resin include an ethylene / vinyl acetate copolymer and an ethylene / ethyl acrylate copolymer.

As the MI of the polyethylene resin decreases, the moldability decreases, the surface smoothness of the molded product decreases,
Since the mechanical strength of the obtained foam decreases as the size increases, 0.1 to 40 is preferable, and more preferably 0.1 to 40.
~ 30.

If the proportion of the polypropylene resin contained in the polyolefin resin increases, the resulting foam loses its flexibility, which is not preferable, and is therefore not more than 85% by weight.

The ammonium polyphosphate compound used in the present invention is a compound having a repeating unit represented by the general formula (2).

[0020]

Embedded image [In the general formula (2), m represents a natural number of 50 or less;
Is a chemical structural formula represented by NH ₄ or the general formula (3). ]

[0021]

Embedded image

Examples of the ammonium polyphosphate-based compound include ammonium polyphosphate and melamine-modified ammonium polyphosphate. As the melamine-modified ammonium polyphosphate, Sumisef PM manufactured by Sumitomo Chemical Co., Ltd. is commercially available. I have.

When the amount of the ammonium polyphosphate compound is small, the flame retardancy of the obtained foam is reduced, and when the amount is large, the improvement of the flame retardancy is saturated. Therefore, the polyethylene resin or the polyolefin resin mixture is used. 100
It is 10 to 50 parts by weight with respect to parts by weight.

The nitrogen-containing heterocyclic compound (A) used in the present invention includes, for example, ethylene urea, hydantoin, hexahydropyrimidin-2-one, piperazine-
Reaction products of 3,6-dione, barbituric acid and the like with formaldehyde can be mentioned.

Examples of the nitrogen-containing heterocyclic compound (B) used in the present invention include a reaction product of ethylene thiourea and formaldehyde. The reaction product is, for example, 50 g of ethylene thiourea and 1 liter of water. , And mixed with a dilute acid (sulfuric acid or phosphoric acid) to adjust the pH of the solution to 2, and the solution was heated to 90 ° C.
A weight% aqueous solution of formaldehyde was added dropwise to ethylene thiourea until the molar ratio of formaldehyde / ethylene thiourea became 2, followed by vigorous stirring while maintaining at 90 ° C. The precipitate obtained is filtered, washed with water and dried.

The reaction product of ethylene urea and formaldehyde can be obtained by applying the same method as described above.

The nitrogen-containing heterocyclic compound (C) used in the present invention includes, for example, 2-piperazinylene-4-
An oligomer or polymer of morpholino-1,3,5-triazine and the like can be mentioned, and the oligomer or polymer can be obtained, for example, by the following method.

An equimolar amount of 2,6-dihalo-4-morpholino-1,3,5-triazine (eg, 2,6-dichloro-4-morpholino-1,3,5-triazine) and piperazine are combined with an organic base. Alternatively, a heating reaction is performed in xylene in the presence of an inorganic base (for example, triethylamine, tributylamine, sodium hydroxide, potassium hydroxide, sodium carbonate, and the like), and after the completion of the reaction, the reaction product is separated by filtration.
The obtained solid is washed with boiling water to remove salts of by-products, and then dried to obtain a remaining solid.

When the amount of the nitrogen-containing heterocyclic compound is small, the flammability of the obtained foam is reduced, and the flame retardancy is saturated even when the amount is large. Therefore, 100 parts by weight of the polyethylene resin or polyolefin resin mixture is used. For the department,
5 to 20 parts by weight.

The petroleum resin used in the present invention is, for example, a thermo- or cation-polymerized diolefin, mono-olefin, or aromatic compound contained in a cracked fraction in petroleum refining or petroleum cracking. And a plastic resin.

[0031] Examples of the thermoplastic resin, among the decomposition fraction, C ₅ aliphatic fraction C ₅ system to feed the petroleum resin, aromatic of C ₉ system in which the raw material C ₉ fraction Petroleum resin,
C ₅ fraction and C ₉ fraction copolymer-based petroleum resin containing, C ₅ fraction dicyclopentadiene petroleum resin cyclopentadiene were dicyclopentadiene obtained by thermally dimerizing the starting material contained, further , 2 in the above petroleum resin
Examples of hydrogenated heavy bonds include:
Hydrogenated materials having excellent heat resistance and weather resistance are preferred.

The petroleum resin includes Quinton A-1
00 (manufactured by Zeon Corporation), Alcon P-140 (manufactured by Arakawa Chemical Industries), Escolets E5320 (manufactured by Exxon Chemical), and the like.

When the amount of the petroleum resin is reduced,
The effect of preventing bleeding of an ammonium polyphosphate compound or a nitrogen-containing heterocyclic compound under high humidity of the obtained foam is reduced, and when it is increased, the flexibility, elongation, mechanical properties such as breaking strength of the obtained foam are reduced. Because of the lowering, the amount is 1 to 25 parts by weight based on 100 parts by weight of the polyethylene-based resin or polyolefin-based resin mixture.

The thermal decomposition type organic foaming agent used in the present invention is not particularly limited as long as it generates a decomposition gas by heating. For example, azodicarbonamide, benzenesulfonyl hydrazide, dinitrosopentamethylenetetramine , Toluenesulfonyl hydrazide,
4,4-oxybis (benzenesulfonyl hydrazide)
These may be used alone or in combination of two or more.

When the amount of the above-mentioned thermal decomposition type organic foaming agent is small, the foaming ratio is low, and when the amount is large, foaming unevenness such as partial formation of large bubbles is generated and uniform foaming property is reduced. Alternatively, the amount is 1 to 40 parts by weight based on 100 parts by weight of the polyolefin resin mixture.

The composition for foaming a flame-retardant polyolefin resin of the present invention has a low foaming property such as hydrated metal oxides and red phosphorus as long as foaming properties such as high foaming properties, uniform foaming properties and high closed-cell properties are not impaired. Flame aids may be added.Examples of the hydrated metal hydroxide include known aluminum hydroxide, magnesium hydroxide, and basic magnesium carbonate. From the viewpoints of moisture resistance and safety (spontaneous ignition during kneading), it is preferable to use red phosphorus particles whose surfaces are coated with a resin.

If the amount of the flame-retardant aid is too large, the foaming properties are reduced, so 100 parts by weight of the polyethylene-based resin or polyolefin-based resin mixture is used.
It is preferably at most part by weight.

When producing a foam using the flame-retardant polyolefin-based resin foaming composition of the present invention, if necessary, such as improvement of the heat resistance of the foam to be obtained and the foaming method, the foam may be prepared before foaming. Crosslinking is preferably performed.

Examples of the crosslinking method include a method in which a radical generator such as a peroxide mixed in advance with the flame-retardant polyolefin-based resin foaming composition is thermally decomposed to crosslink, a method of crosslinking by irradiation with ionizing radiation, and a method of crosslinking. A method of adding a functional monomer as a crosslinking assistant in advance to the composition for foaming a flame-retardant polyolefin resin, further adding a peroxide and thermally crosslinking or a method of crosslinking by ionizing radiation, and a method of using a silane crosslinking agent. No.

The peroxide may be any one which is generally used as a radical generator. Examples of the peroxide include benzoyl peroxide, octanoyl peroxide, decanoyl peroxide, acetyl peroxide,
t-butyl peroxyisobutyrate, cumene hydroperoxide and the like.

Examples of the silane crosslinking agent include trimethoxyvinylsilane and triethoxyvinylsilane.

When the crosslinking is carried out, if the proportion of the polyethylene resin contained in the polyolefin resin is 80% by weight or less, a crosslinking aid is added to the flame-retardant polyolefin resin foaming composition in advance. Is preferred.

The crosslinking assistant may be any functional monomer which causes a crosslinking reaction by ionizing radiation such as electron beam or γ-ray or a peroxide. 1 allyl group and (meth) acryloyl group
An aromatic or aliphatic compound containing one or two or more in the molecule is exemplified.

Examples of the functional monomer include divinylbenzene, diallylbenzene, divinylnaphthalene, trimethylolpropane trimethacrylate, ethylvinylbenzene, 1,9-nonanediol dimethacrylate, 1-nonane monomethacrylate, 1,6 -Hexanediol methacrylate, 2,2-bis [4- (acryloxydiethoxy) phenyl] propane, 1,2,2
4-benzenetricarboxylic acid triallyl ester, 1,
2-benzenedicarboxylic acid diallyl ester, 1,3-
Examples thereof include diallyl benzenedicarboxylate and diallyl 1,4-benzenedicarboxylate, which may be used alone or in combination of two or more. .

If the amount of the crosslinking aid is too small, crosslinking is insufficient and a uniform foam cannot be obtained, and the mechanical strength at high temperature decreases. If the amount increases, the degree of crosslinking increases and the expansion ratio decreases. The amount is preferably 0.05 to 10 parts by weight based on 100 parts by weight of the polyolefin resin.

The degree of crosslinking can be determined, for example, by heating a sample of weight (ag) in xylene at 120 ° C. for 24 hours,
It is calculated from the dry weight (bg) of the residue after filtration through a 200 mesh wire mesh.

Degree of crosslinking (%) = (b / a) × 100

The flame-retardant polyolefin resin foaming composition used in the present invention may contain an antioxidant, a stabilizer, a filler, a pigment, a metal harm inhibitor, etc., according to the purpose. .

As the antioxidant, known phenolic, phosphorus, sulfur, and amine compounds can be used. For example, phenolic tris (3,5-di-t-butyl-4-hydroxybenzyl) Isocyanurate, tetrakis [methylene-3- (3 ′, 5′-di-t-butyl-
4-hydroxyphenyl) propionate] methane, propyl gallate and the like, and phosphorus-based triphenyl phosphite, 9,10-dihydro-9-oxa-10-
Phosphaphenanthrene-10-oxide, 2,2-
Methylenebis (4,6-di-t-butylphenyl) octyl phosphite; and sulfur-based dilauryl-3,3′-thiodipropionate, bis [2
-Methyl-4- (3-dodecanylthiopropionyloxy) -5-t-butylphenyl] sulfide, laurylstearyl-3,3'-thiodipropionate, and the like. These may be used alone or in combination of two or more.

The addition amount of the above antioxidant is preferably in the range of 0.1 to 5 parts by weight based on 100 parts by weight of the polyethylene resin or polyolefin resin mixture.

The composition for foaming a flame-retardant polyolefin resin of the present invention is prepared by, for example, mixing the components and using a kneading device such as a single-screw extruder, a twin-screw extruder, a Banbury mixer, a kneader mixer, or a roll. The mixture is melt-kneaded, and then formed into a sheet or plate using an extruder or a calendar roll equipped with a mold. The obtained sheet-like or plate-like molded body is irradiated with ionizing radiation to crosslink, and then heated and foamed in a hot-blast furnace to obtain a foamed body. The irradiation and foaming may be performed continuously or in a batch system.

The ionizing radiation includes an electron beam, γ
Although an electron beam, an X-ray, and a neutron beam are mentioned, an electron beam is most preferably used, and the irradiation dose is generally 1 to 10 Mrad.

[0053]

Next, embodiments of the present invention will be described. Hereinafter, "parts" means "parts by weight".

(Example 1) 70 parts of polypropylene of MI1.5, density of 0.92 g / cm ³ , 30 parts of linear low-density polyethylene of MI 7.0, ammonium polyphosphate (manufactured by Sumitomo Chemical Co., trade name; P) 15 parts, 17 parts of a reaction product of ethylene urea and formaldehyde, 5 parts of Quinton A-100 (manufactured by Nippon Zeon), 1 part of divinylbenzene (manufactured by Wako Pure Chemical Industries), trimethylolpropane trimethacrylate 1.5 parts and 10 parts of azodicarbonamide (manufactured by Otsuka Chemical Co., Ltd.) were mixed, and the mixture was heated using a heating roll.
Melt kneading at 170 ° C. for 5 minutes, and then forming temperature 170
Press forming at 1.0 ° C. to obtain a sheet having a thickness of 1.0 mm.
A cross-linked sheet was obtained by irradiating a dose corresponding to 0 Mrad to obtain a cross-linked sheet. Then, the cross-linked sheet was heated and foamed in an oven controlled at 250 ° C to obtain a foamed sheet.

(Example 2) 50 parts of MI1.5 polypropylene, density of 0.92 g / cm ³ , MI 7.0 linear low-density polyethylene 50 parts, ammonium polyphosphate 25
Parts, 2-piperazine-4-morpholino-1,3,5-triazine polymer, 15 parts, Alcon P-140 (manufactured by Arakawa Chemical Industries) 10 parts, trimethylolpropane trimethacrylate 1.5 parts, Example 1 was repeated except that 2.5 parts of, 9-nonandiol methacrylate (manufactured by Shin-Nakamura Chemical) and 10 parts of azodicarbonamide (manufactured by Otsuka Chemical) were used.
In the same manner as in the above, a foamed sheet was obtained.

(Example 3) 60 parts of MI1.5 polypropylene, density of 0.92 g / cm ³ , MI3.4 low-density polyethylene 40 parts, ammonium polyphosphate 30 parts,
8 parts of piperazine-4-morpholino-1,3,5-triazine polymer, 15 parts of Alcon P-140 (manufactured by Arakawa Chemical Industries), 5 parts of Escolets E5320 (manufactured by Exxon Chemical), trimethylolpropane trimethacrylate
A foamed sheet was obtained in the same manner as in Example 1, except that 2 parts of 1, 2,2,4-benzenetricarboxylic acid triallyl ester (manufactured by Wako Pure Chemical Industries, Ltd.) and 1.5 parts of azodicarbonamide were used. .

Example 4 Density 0.92 g / cm ³ , M
I3.4 100 parts of low density polyethylene, 35 parts of ammonium polyphosphate, 2-piperazine-4-morpholino-
5 parts of 1,3,5-triazine polymer, 5 parts of a reaction product of ethylene urea and formaldehyde, Quinton A-
100 (manufactured by Nippon Zeon) 5 parts, Escolets E5320
A foamed sheet was obtained in the same manner as in Example 1, except that 11 parts (manufactured by Exxon Chemical) and 10 parts of azodicarbonamide were used.

Comparative Example 1 MI1.5 Polypropylene 1
00 parts, 150 parts of ammonium polyphosphate (manufactured by Sumitomo Chemical Co., trade name; Smithef P), 20 parts of 2-piperazine-4-morpholino-1,3,5-triazine polymer, and reaction formation between ethylene urea and formaldehyde 20 parts,
5 parts of Quinton A-100 (manufactured by Nippon Zeon), 1405 parts of Alcon P, 1.5 parts of trimethylolpropane trimethacrylate, triallyl ester of 1,2,4-benzenetricarboxylic acid (manufactured by Wako Pure Chemical Industries) ) Heating in an oven in the same manner as in Example 1 except that 1 part and 10 parts of azodicarbonamide were used, but no foaming occurred.

Comparative Example 2 MI1.5 Polypropylene 3
0 parts, density 0.92 g / cm ^3, 40 parts of MI7.0 linear low density polyethylene, density 0.92 g / cm ^3, MI
3.4 30 parts of low density polyethylene, 5 parts of ammonium polyphosphate, 50 parts of a reaction product of ethylene urea and formaldehyde, Quinton A-10020 parts, 1.5 parts of trimethylolpropane trimethacrylate, 1,9 -Nonandiol-dimethacrylate (manufactured by Shin-Nakamura Chemical) 2.5
Parts and 10 parts of azodicarbonamide,
A foam sheet was obtained in the same manner as in Example 1.

Comparative Example 3 MI1.5 Polypropylene 8
0 parts, density 0.92 g / cm ³ , MI 3.4 low density polyethylene 20 parts, ammonium polyphosphate 3 parts, 2-piperazine-4-morpholino-1,3,5-triazine polymer-2 parts, ethylene urea and formaldehyde 2 parts of a reaction product with Escolez E5320 (manufactured by Exxon Chemical), 1 part of trimethylolpropane trimethacrylate, 1.5 parts of 1,2,4-benzenetricarboxylic acid triallyl ester and azodicarbonamide A foamed sheet was obtained in the same manner as in Example 1 except that 10 parts (manufactured by Otsuka Chemical) were used.

The sheets heated in the foamed sheets or ovens obtained in Examples 1 to 4 and Comparative Examples 1 to 3 were subjected to a combustion test, a measurement of expansion ratio, and an appearance inspection. Are shown in Table 1.

In the above combustion test, the flammability classification was determined according to JIS D1201. The appearance was visually inspected, and x was given when there was uneven foaming, and x was given when there was no unevenness. The expansion ratio was determined by measuring the specific gravity of the foam sheet and expressed as the reciprocal of the specific gravity.

[0063]

[Table 1]

EFFECT OF THE INVENTION Since the composition for foaming a flame-retardant polyolefin resin of the present invention has the structure described above, it has self-extinguishing properties without containing a halogen-containing compound, and has excellent foaming properties. Since a foam having an excellent appearance can be produced, the foam is suitable for uses of the foam requiring flame retardance, particularly as an interior member for automobiles and a member for construction.

Claims (1)

(57) [Claims] 1. A polyolefin resin (100 parts by weight), an ammonium polyphosphate compound (10 to 50 parts by weight), and at least one nitrogen-containing complex selected from the group consisting of the following (A), (B) and (C): 5 to 20 parts by weight of a cyclic compound, 1 to 50 parts by weight of a petroleum resin, and 1 to 40 parts of a pyrolytic organic blowing agent
What is claimed is: 1. A composition for foaming a flame-retardant polyolefin resin, comprising: parts by weight, wherein the melt index of the polyolefin resin is 0.1 to 40 g / 10 minutes. object. (A) a reaction product group of formaldehyde and a cyclic ketone comprising a 5-membered or more heterocyclic ring containing two or more nitrogen atoms in the ring; and (B) a reaction product group containing two or more nitrogen atoms in the ring. (C) 1,3,5-triazine derivative group having a repeating unit represented by the following general formula (1), [In the general formula (1), X represents a morpholino group or a pipezino group, Y represents a divalent group derived from piperazine, and n represents 2
Represents a natural number of ~ 50. ]