JPH08113662A - Highly flame-retardant resin foam - Google Patents

Abstract

PURPOSE: To produce a polyolefin resin foam which is esp. excellent in flame retardance and reduced in the deterioration in mechanical strengths. CONSTITUTION: This highly flame-retardant resin foam is obtd. by cross-linking and foaming a resin compsn. which comprises 100 pts.wt. ethylene-vinyl acetate copolymer resin or its mixture with other polyolefin resins (provided the vinyl acetate content of the resin or mixture is 5-20wt.%), 50-200 pts.wt. hydrated metal oxide, and 5-100 pts.wt. mixture of 90-10wt.% neutralized thermally expandable graphite and 10-90wt.% phosphorus compd.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a highly flame-retardant resin foam.

[0002]

2. Description of the Related Art Resin foams have excellent heat insulating properties and are used in a wide range of applications such as building materials, transportation equipment such as automobiles, packaging materials, household products and the like. In particular, the polyolefin resin foam has excellent chemical stability and excellent properties such as heat insulating property, electric insulating property, and light weight, and therefore its demand is extremely large. However, with the expansion of uses of polyolefin resin foams, it is strongly required to be a flame-retardant material, and flame-retardant treatment is performed by various methods.

In recent years, a method of adding a halogen-containing compound has been generally used as a method for making a polyolefin resin flame-retardant. These flame-retardant treatments certainly have a flame-retardant effect, and the deterioration of moldability and mechanical strength of molded products is relatively small, but a large amount of gas is generated during processing and combustion, and equipment is corroded. There is a strong demand for a non-halogen flame-retardant treatment from the viewpoint of safety, as it causes problems such as causing damage to the human body and spreading damage to the human body.

[0004]

[Problems to be Solved by the Invention] In such a situation,
Aluminum hydroxide, which does not generate harmful gas when burning,
The study of flame retardancy of resins by adding hydrated metal oxides such as magnesium hydroxide and basic magnesium carbonate has become popular. However, in order to impart sufficient flame retardancy to a polyolefin resin that is easily flammable only with these hydrated metal oxides, a large amount of the above hydrated metal oxides must be added, and as a result, The physical properties of the resulting foam are remarkably deteriorated, and the state of foaming is also affected, making it difficult to form a fine and uniform closed cell structure.

Further, in Japanese Patent Laid-Open No. 3-41163,
Containing 0.1 to 50% by weight of an alkaline earth metal compound or metal hydroxide (A) and 0.01 to 5% by weight of thermally expandable graphite coated with a film-forming resinous substance (B). Although flame-retardant thermoplastic resin compositions have been proposed, thermal expansion graphite is scattered by rapid heating even when the proposed examples are repeated, and the shielding layer is formed only incompletely. The flame retardance cannot be imparted to the thermoplastic resin.

Further, in JP-A-60-152542, a polyethylene resin or a copolymer resin mainly composed of ethylene is added with a phosphorus-based flame retardant and triphenylantimony which do not impair the transparency of these resins. A flame-retardant polyolefin resin composition has been proposed, and among many compounds as the phosphorus-based flame retardant, ammonium polyphosphate is exemplified as one of the compounds, but a flame-retardant heat containing the thermally expandable graphite. Similar to the plastic resin composition, the shielding layer is formed only incompletely, and sufficient flame retardancy cannot be imparted to the thermoplastic resin.

Further, in the flame retarding treatment method disclosed in Japanese Patent Laid-Open No. 63-61055, a two-component mixed flame retardant of ammonium polyphosphate and tris (2-hydroxyethyl) isocyanurate is added to a polyolefin resin. Although used, the described resin composition has a short-term flame retardant effect, but has a problem in the persistence of the effect, that is, a foam obtained from the resin composition, for example, a folded plate roof. When used under high temperature conditions such as the dew condensation preventing backing material, the above flame retardant bleeds out and the long-term flame retardant effect cannot be maintained.

Further, the above flame retardant has a problem in production technology that, when it is kneaded with a polyolefin resin, the foaming agent is liable to undergo initial decomposition and temperature control in the foaming process becomes difficult. .

Further, JP-A-6-25476 discloses a polyolefin, red phosphorus, rapid heating (800 to 1000 ° C.).
A flame-retardant polyolefin-based resin composition containing a heat-expandable graphite that has 100 times or more the expandability in the C-axis direction and contains 80 mesh on 80% or more by classification is described. The heat-expandable graphite is obtained by treating it with an inorganic acid and a strong oxidant in the manufacturing process, and the polyolefin resin composition containing such heat-expandable graphite is impaired in its stability. When kneading and molding the polyolefin resin composition,
There is a problem that these mechanical devices are corroded, and they cannot be applied to polyolefin resin foams at all.

The present invention has been made in view of the above facts, and it is an object of the present invention that the mechanical strength is not significantly reduced, the flame retardancy is excellent, and the apparatus is corroded during molding. It is to provide a polyolefin-based resin foam that does not cause the deterioration.

[0011]

[Means for Solving the Problems]

In the present invention, ethylene is used as a resin component.
When the vinyl acetate copolymer resin is used alone, the ethylene-vinyl acetate copolymer resin has a vinyl acetate content of 5 or less.
Those within the range of up to 20% by weight are used. When the resin component is composed of the ethylene-vinyl acetate copolymer resin and another polyolefin resin, the ethylene-vinyl acetate copolymer resin has a vinyl acetate content of 1 or less.
If a resin in the range of 0 to 25% by weight is selected, the ethylene-vinyl acetate copolymer resin is used as a resin component consisting of 50 to 75 parts by weight and another polyolefin resin 25 to 50 parts by weight, and It is compounded so that the vinyl acetate content is in the range of 5 to 20% by weight.

The vinyl acetate content in all the above resin components is 5
If it is less than 20% by weight, it becomes difficult to mix the above-mentioned inorganic compound, especially the hydrated metal oxide into the resin component, and if it exceeds 20% by weight, the tackiness becomes large and the moldability becomes poor. Further, free acetic acid is likely to be generated during melt-kneading, which deteriorates the resin and deteriorates the physical properties of the obtained resin molded product.

As the other polyolefin resin,
Although not particularly limited, for example, α-olefin polymers such as polyethylene, polypropylene and polybutene, ethylene-propylene copolymers, ethylene-propylene-diene terpolymers, ethylene-ethyl acrylate copolymers, ethylene-butene copolymers, ethylene- Butene-diene terpolymer and the like are preferably used.

The melt index (MI) of the resin component is preferably 1-15. When MI is less than 1, the moldability is poor because the viscosity is high, and when MI exceeds 15, the physical properties of the obtained resin foam are deteriorated.

The hydrated metal oxide used in the present invention includes aluminum hydroxide, magnesium hydroxide,
Examples thereof include basic magnesium carbonate, calcium hydroxide, barium hydroxide and the like. These hydrated metal oxides are 1
Although only the seed may be blended, it may be blended as a mixture of two or more species. A mixed system of aluminum hydroxide and magnesium hydroxide is particularly preferable because high flame retardancy can be obtained.

The amount of the hydrated metal oxide is 50 to 200 parts by weight based on 100 parts by weight of the resin component.
If it exceeds 100 parts by weight, the mechanical strength of the obtained resin foam is largely reduced and it cannot be put to practical use. If it is less than 50 parts by weight, sufficient flame retardancy cannot be obtained.

The thermally expansive graphite used in the present invention according to claim 1 is powdery graphite such as natural scaly graphite, pyrolytic graphite, and Kish graphite, and sulfuric acid, nitric acid, selenic acid, etc. and concentrated nitric acid, perchlorine. Graphite in which oxygen, water and hydrogensulfate groups enter between the layered structures of graphite after acid treatment with strong oxidants such as acid, perchlorate, permanganate, dichromate, hydrogen peroxide -It is a crystalline compound in which an intercalation compound such as sulfuric acid is generated and which maintains the layered structure of carbon.

The heat-expandable graphite used in the present invention according to claims 2 to 6 is obtained by treating the heat-expandable graphite obtained by the acid treatment as described above with ammonia, an aliphatic lower amine,
Those neutralized with an alkali metal compound, an alkaline earth metal compound or the like are used.

Examples of the aliphatic lower amine include monomethylamine, dimethylamine, trimethylamine, ethylamine, propylamine and butylamine. Examples of the above-mentioned alkali metal compound and alkaline earth metal compound include hydroxides, oxides, carbonates, bicarbonates, sulfates, organic acid salts and the like of potassium, sodium, calcium, barium, magnesium and the like.

The above-mentioned thermally expandable graphite has a particle size of 20 to 200.
A mesh is preferable. If the particle size is smaller than 200 mesh, the degree of expansion of the heat-expandable graphite is small,
As a result, the flame retardance decreases, and if it is coarser than 20 mesh,
The dispersibility in the resin component is poor, and the physical properties of the resulting foam cannot be avoided.

The phosphorus compound used in the present invention according to claim 2 is triphenyl phosphate, tricresyl phosphate, trixylenyl phosphate,
Phosphoric acid esters such as cresyl phenyl phosphate and xylenyl diphenyl phosphate, metal phosphates such as sodium phosphate, potassium phosphate, magnesium phosphate and the like can also be used, but they are used in the present invention according to claim 3. Red phosphorus, polyphosphoric acid salts such as ammonium polyphosphate used in the present invention described in claim 4 and the phosphorus compound represented by the following general formula (1) used in the present invention described in claim 3 are difficult It is more preferable from the viewpoint of imparting flammability.

[0023]

Embedded image

The red phosphorus may be a commercially available red phosphorus, but from the viewpoint of moisture resistance and safety (ignition during kneading of the resin composition), the surface of red phosphorus is preferably coated with a synthetic resin or the like.

Examples of the polyphosphates include ammonium polyphosphate and melamine-modified ammonium polyphosphate. Only one of these may be blended, or they may be blended as a mixture. These polyphosphates have a polymerization degree of 200 to 1,000, and a free-flowing powder which is hardly soluble in water and whose surface is coated with a melamine-formaldehyde resin or the like is preferably used.

Examples of the phosphorus compound represented by the above general formula (1) include methylphosphonic acid, dimethylphosphonic acid, diethyl methylphosphonate, ethylphosphonic acid, propylphosphonic acid, butylphosphonic acid, 2-methylpropylphosphonic acid, t-butylphosphonic acid, 2,3-dimethyl-butylphosphonic acid, octylphosphonic acid, phenylphosphonic acid, dioctylphenylphosphonate, dimethylphosphinic acid, methylethylphosphinic acid, methylpropylphosphinic acid, diethylphosphinic acid, dioctylphosphinic acid, Examples thereof include phenylphosphinic acid, diethylphenylphosphinic acid, diphenylphosphinic acid and bis (4-methoxyphenyl) phosphinic acid. The above phosphorus compounds may be used alone or in combination of two or more.

The compounding ratio of the thermally expansive graphite and the phosphorus compound used in the present invention according to claims 1 and 2 is 9: 1 to
The ratio is 1: 9 (weight ratio), preferably 9: 1 to 3: 7, and more preferably 8: 2 to 5: 5. This is because when the amount exceeds the above range, there is almost no difference from the low flame retardancy exhibited when each is used alone.

The blending amount of the flame-retardant mixture of thermal expansion graphite and ammonium polyphosphate with respect to 100 parts by weight of the resin component is 5 to 200 parts by weight, but when it exceeds 200 parts by weight, a resin foam obtained. The mechanical strength of the above is so large that it cannot be put to practical use, and if it is less than 5 parts by weight, sufficient flame retardancy cannot be obtained.

Further, the above resin component composition may be mixed with a phenol-based compound within a range that does not impair the physical properties of the resulting foam.
An amine-based or sulfur-based antioxidant, a metal damage inhibitor, a filler, an antistatic agent, a stabilizer, a cross-linking agent, a lubricant, a softening agent, a colorant and the like may be added.

In the resin composition of the present invention, the resin component is cross-linked in order to obtain the viscosity required to withstand the foaming in the foaming step and to improve the heat resistance of the foam obtained. In the present invention, as the method of crosslinking, any method may be adopted, but a method of thermally decomposing a radical generator such as a peroxide mixed with a polyolefin-based resin to perform crosslinking, and ionizing radiation A crosslinking method by irradiation, a method by silane crosslinking, etc. can be used.

As the ionizing radiation, electron beam, X-ray, β
Rays, γ rays, neutron rays, etc. are used. The irradiation dose is generally about 1 to 10 Mrad, and the dose is set according to the desired gel fraction.

Examples of the radical generator include benzoyl peroxide, octanoyl peroxide, decanoyl peroxide, acetyl peroxide, t-butylperoxyisobutyrate, cumene hydroperoxide and the like. Examples of the silane crosslinking agent include trimethoxyvinylsilane, triethoxyvinylsilane and the like.

In the present invention, a crosslinking aid may be used when the above crosslinking is carried out. The above-mentioned cross-linking aid may be a polyfunctional monomer and may be one which causes a cross-linking reaction by ionizing radiation or a peroxide, and two or more kinds of these may be mixed and used. Typical examples of the above-mentioned crosslinking aid are aromatic or aliphatic compounds containing one or more vinyl groups or allyl groups in one molecule and acryloyloxy group or methacryloyloxy group in one molecule. A compound containing one or more than one, specifically, for example, divinylbenzene, diallylbenzene,
Divinylnaphthalene, trimethylolpropane trimethacrylate, ethylvinylbenzene, 1,9-nonanediol dimethacrylate, 1-nonanemonomethacrylate, 1,6-hexanediol methacrylate, 2,2
-Bis [4- (acryloxydiethoxy) phenyl] propane, 1,2,4-benzenetricarboxylic acid triallyl ester, 1,2-benzenedicarboxylic acid diallyl ester, 1,3-benzenedicarboxylic acid diallyl ester, 1, Examples include 4-benzenedicarboxylic acid diallyl ester and related homologs thereof.

The amount of the above-mentioned crosslinking aid compounded is 0.05 to 10 parts by weight, more preferably 0.5 to 10 parts by weight, based on 100 parts by weight of the total amount of the above resin components. It is set accordingly. The amount of the above-mentioned crosslinking aid compounded is 0.05
If the amount is less than parts by weight, the crosslinking is insufficient, so that a fine and uniform foam structure cannot be obtained, and sufficient material strength at high temperature cannot be obtained. If the blending amount exceeds 10 parts by weight, the cross-linking density of the resin composition becomes too large, which causes problems such as difficulty in molding a rough sheet of the resin composition before foaming.

The foaming agent used in the present invention has a decomposition temperature higher than the melting temperature of the above resin component and may generate gas when heated to a temperature higher than the decomposition temperature, for example, , Azodicarbonamide, N, N-dinitrosopentamethylenetetramine, benzenesulfonyl hydrazide, toluenesulfonyl hydrazide, 4,4-
Examples include organic foaming agents such as oxybis (benzenesulfonyl hydrazide) and inorganic foaming agents such as sodium bicarbonate and ammonium carbonate. The blending amount of the foaming agent varies depending on the expansion ratio based on the use of the resulting foam,
It is usually 15 to 30 parts by weight.

In the present invention, each component of the above resin composition is mixed with a kneading machine such as a single-screw extruder, a multi-screw extruder, a Banbury mixer, a kneader mixer, and two rolls at a temperature at which the foaming agent does not decompose, for example, The mixture is melt-kneaded at a temperature of about 130 to 170 ° C. and then formed into an appropriate shape, for example, a sheet shape. After the obtained sheet-shaped molded product is irradiated with ionizing radiation to crosslink the resin, the temperature is not lower than the decomposition temperature of the thermal decomposition type foaming agent and is the melting point of the resin, for example, by hot air, infrared rays, a metal bath, an oil bath, or the like. Above temperature, for example 170-
It is heated to 290 ° C. and the resin is foamed by the decomposition gas of the foaming agent to obtain a crosslinked resin foamed sheet. These irradiation and foaming steps may be performed continuously or in a batch manner.

[0037]

According to the present invention as set forth in claims 1 to 6, as described above, the content of vinyl acetate in the resin component comprising ethylene-vinyl acetate copolymer resin or this and other polyolefin resin is 5 to 20% by weight. Since the resin component is selected to be within the range, the hydrated metal oxide, the thermally expansive graphite, the inorganic component such as ammonium polyphosphate and the foaming agent can be uniformly dispersed in the resin component, Moreover, it is possible to impart preferable moldability to give a foam having a uniform foam structure and a beautiful appearance.

Further, in the present invention according to claim 1, 50 to 200 hydrated metal oxides are added to 100 parts by weight of the resin component.
5 parts by weight, 9: 1 to 1: 9 (weight ratio) of a mixture of thermally expandable graphite and ammonium polyphosphate (ammonium polyphosphate or ammonium polyphosphate modified with melamine) 5 to 5
By using the resin composition consisting of 200 parts by weight, when the heat-expandable graphite is used alone, the heat-expandable graphite scatters due to abrupt heating, and a shielding layer having excellent heat insulation properties at a sharp angle is obtained. It does not exhibit sufficient performance, etc., and the strong composite shielding layer of thermally expansive graphite and ammonium polyphosphate covers the combustible components sufficiently, so it is excellent in combination with the fire extinguishing function of hydrated metal oxides. It is possible to provide a flame-retardant resin foam.

The present invention according to claim 2 provides the above resin component 1
50 to 200 parts by weight of the hydrated metal oxide, and 9: 1 of the neutralized thermally expansive graphite and phosphorus compound with respect to 00 parts by weight.
By using a resin composition consisting of 5 to 100 parts by weight of the compound of 1: 9 (weight ratio), when the thermally expandable graphite is used alone, the thermally expandable graphite scatters due to rapid heating. However, since the shielding layer having excellent heat insulation property does not exhibit sufficient performance, the strong composite shielding layer of thermally expansive graphite and phosphorus compound sufficiently covers the flammable component, so that hydration is possible. An excellent flame-retardant resin foam can be provided in combination with the fire extinguishing function of the metal oxide.

In the present invention according to claim 3, the phosphorus compound used in the present invention according to claim 2 is specified to be red phosphorus, whereby the flame retardant action of red phosphorus on the polyolefin resin is synergistic. In addition, it is possible to provide a more advanced flame-retardant resin foam.

The present invention according to claim 4 is characterized in that the phosphorus compound used in the present invention according to claim 2 is ammonium polyphosphate or melamine-modified ammonium polyphosphate, whereby ammonium polyphosphate or melamine-modified ammonium polyphosphate is specified. Flame-retardant action on the above-mentioned polyolefin-based resin has a synergistic effect,
Furthermore, it is possible to provide a highly flame-retardant resin foam.

In the present invention according to claim 5, the phosphorus compound used in the invention according to claim 2 is specified as the phosphorus compound represented by the above general formula (1) to obtain the above general formula ( The phosphorus compound represented by 1) has a synergistic flame retardant action on the above-mentioned polyolefin resin, and can provide a flame-retardant resin foam having a higher degree.

In the present invention according to claim 6, the heat-expandable graphite used in the present invention according to claim 2 is neutralized with ammonia, an aliphatic lower amine, an alkali metal compound or an alkaline earth metal compound. Therefore, the foamable polyolefin resin flame-retardant composition of the present invention is molded under conditions of high temperature and high pressure, in the step of foaming, without causing alteration or deterioration, and also in the plant used for the above-mentioned processing such as corrosion. It is possible to provide a highly flame-retardant resin foam that is stable for a long time without causing any damage.

As described above, the present invention uses constituents which are safe to animals including humans and widely to the environment, except for general dust, and the halogen-free combustible resin composition is highly flame-retardant. As a result, its application can be expanded to a wide range including automobile interior organic materials and building materials.

The present invention also comprises crosslinking the above resin composition,
Since it is foamed, it is possible to provide a flame-retardant resin foam which is fine and has a uniform foam structure.

[0046]

EXAMPLES Examples and comparative examples of the present invention will be described below. In the examples, each of the combustion test, foaming state, and appearance test was measured and evaluated by the methods described below.

1. Combustion test Measured in accordance with JIS D 1201 (combustibility test method for organic materials for automobile interiors), an oxygen index of 30 or more is ◯,
An oxygen index of less than 30 was evaluated in two grades of x.

2. Foamed state The cross section and the longitudinal section of the obtained foamed sheet are randomly selected to be 5 each.
The visual field is set, and it is visually observed whether or not the diameter of the bubbles is fine and uniform, and whether the foaming state has an adverse effect on the appearance of the sheet. evaluated.

3. Appearance The surface condition of the obtained foamed sheet was comprehensively visually inspected for the smoothness of the surface, the degree of discoloration, etc., and was evaluated in two stages of ◯: good and ×: poor.

The materials used in the examples and comparative examples are shown below. EVA: vinyl acetate content 19% by weight, density 0.94 g
/ Cm ^3, MI = 2.5 ethylene - vinyl acetate copolymer LDPE: density 0.92g / cm ^3, MI = 3.4 low density polyethylene LLDPE: density ^{0.92g / cm 3, MI = 7} . 0 linear low density polyethylene Aluminum hydroxide: manufactured by Nippon Light Metal Co., Ltd., B703S Magnesium hydroxide: manufactured by Kyowa Chemical Industry Co., Ltd., Kisuma 5A Ammonium polyphosphate: Sumitomo Chemical Co., Ltd., Sumisafe P melamine modified ammonium polyphosphate: Sumitomo Chemical Kogyo Co., Ltd., Sumisafe PM Red Phosphorus: Phosphorus Chemical Co., Ltd., Novarred 120 t-butylphosphonic acid: Wako Pure Chemical Industries Co., Ltd. Thermally expandable graphite: Nippon Kasei Co., CA-60S Thermally expandable graphite: Nippon Kasei CA-60S (neutralized product) decabromodiphenyl ether: Asahi Glass Co., AFR-
1021 Antimony trioxide: manufactured by Mikuni Smelting Co., Ltd. Foaming agent: manufactured by Otsuka Chemical Co., azodicarbonamide

(Examples 1 to 5), (Comparative Examples 1 to 6) In each of Examples and Comparative Examples, each material was used in accordance with the compounding ratios shown in Table 1 and Table 2 by using a Labo Plastomill. The mixture was melt-kneaded at 140 ° C. and 60 rpm for 5 minutes to obtain a flame-retardant resin composition. This resin composition was molded at a molding temperature of 14
Hot pressing was performed at 0 ° C. to obtain a foamable sheet having a thickness of 2.5 mm. Next, this foamable sheet is irradiated with a dose corresponding to an absorbed dose of 3.0 Mrad using an electron beam accelerator to crosslink the resin component, and further heated in a hot air type foaming furnace at 240 ° C. to foam. A flame-retardant resin foam was obtained. The performances of the obtained foams are shown in Table 1 and Table 2, respectively.

(Examples 6 to 10), (Comparative Examples 7 to 12) Neutralized thermally expansive graphite Thermally expansive graphite: Nippon Kasei Co., Ltd., CA-60S (neutralization treated product) 1 g was added to pure water 100 cm. Put it in ³ and stir with a stirrer for 5 minutes under 2 temperature conditions of 25 ° C and 100 ° C.
As a result of measuring the pH of the liquid at each time of 0 minutes, 20 minutes, and 30 minutes, it was 9.5 under all conditions. On the other hand, in the case of no neutralization treatment, the pH was 3.23 to 3.33 in the same measurement.

Examples 1 to 5 were prepared according to the blending ratios shown in Tables 3 and 4, except that the thermally expandable graphite in Examples 1 to 5 was replaced with the thermally expandable graphite neutralized with ammonia. Similarly, a flame-retardant resin foam was obtained. The performances of the obtained foams are shown in Table 3 and Table 4, respectively. Example 6
No corrosion was observed on the inner surface of the cylinder of the Labo Plastomill used in Nos. 10 to 10, and the kneading torque was stable for a long time.

[0054]

[Table 1]

[0055]

[Table 2]

[0056]

[Table 3]

[0057]

[Table 4]

[0058]

As described above, the flame-retardant resin foam of the present invention can achieve high flame retardancy. Specifically, the oxygen index is 30 or more, and the one having an oxygen index of more than 30 in JIS D 1201-1973 “Test method for flammability of organic material for automobile interior” is flame retardant 1 of the highest rank category of this test. Belong to the class. As described above, since the flame-retardant resin foam of the present invention has high flame retardancy, it does not generate a harmful substance such as halogen gas during combustion or processing, and thus can be provided for a wide range of applications. In particular, it is suitable for use in the field of building materials and interior materials for automobiles that require high flame retardancy.

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Claims (6)

[Claims] 1. A resin component comprising an ethylene-vinyl acetate copolymer resin or another polyolefin resin (provided that the vinyl acetate content in the resin component is 5 to 20% by weight).
100 to 100 parts by weight of hydrated metal oxide, 50 to 200 parts by weight, 9: 1 to 1 of heat-expandable graphite and ammonium polyphosphate (ammonium polyphosphate or melamine-modified ammonium polyphosphate). A highly flame-retardant resin foam obtained by cross-linking and foaming a resin composition comprising 5 to 200 parts by weight of the compound (9: weight ratio). 2. A resin component comprising an ethylene-vinyl acetate copolymer resin or this and another polyolefin resin (provided that the vinyl acetate content in the resin component is 5 to 20% by weight).
100 to 100 parts by weight, 50 to 200 parts by weight of hydrated metal oxide, and 9: 1 to 1: 9 (weight ratio) of neutralized thermally expandable graphite and phosphorus compound. Thing 5
A highly flame-retardant resin foam obtained by cross-linking and foaming a resin composition consisting of -100 parts by weight. 3. A highly flame-retardant resin foam, wherein the phosphorus compound according to claim 2 is red phosphorus. 4. A highly flame-retardant resin foam, wherein the phosphorus compound according to claim 2 is ammonium polyphosphate or melamine-modified ammonium polyphosphate. 5. A highly flame-retardant resin foam, wherein the phosphorus compound according to claim 2 is a phosphorus compound represented by the following structural formula. Embedded image (In the formula, R ¹ is hydrogen or a linear or branched alkyl group or aryl group consisting of 1 to 16 carbon atoms, R ^1
2 is hydrogen or a linear or branched alkyl group having 1 to 16 carbon atoms, an alkoxy group, an aryl group or an aryloxy group, and R ³ is hydrogen or 1 to 1 carbon atoms
It represents a linear or branched alkyl group or aryl group consisting of six. ) 6. The heat-expandable graphite neutralized according to claim 2, which is a heat-expandable graphite neutralized with ammonia, an aliphatic lower amine, an alkali metal compound or an alkaline earth metal compound. Flammable resin foam.