JP2003165860A - Flame-retardant resin foam - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a resin foam having high flame retardancy, eco-friendly, and having high expansion ratio and flexibility. <P>SOLUTION: This flame-retardant resin foam comprises (A) a thermoplastic polymer, (B) a metal hydroxide and (C) carbon black; wherein the metal hydroxide may be a compounded metal hydroxide of formula (1): m(M<SB>a</SB>O<SB>b</SB>).n(Q<SB>d</SB>O<SB>e</SB>).cH<SB>2</SB>O (wherein, M and Q are metallic elements differing from each other, Q being a metallic element belonging to a group selected from IVa, Va, VIa, VIIa, VIII, Ib and IIb ones; and m, n, (a), b, c, d and e are each a positive number). <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a resin foam having excellent flame retardancy, which is made of a non-halogen material having a low environmental load. This resin foam, for example,
It is preferably used for applications requiring softness and cushioning properties such as internal insulators of electronic devices, cushioning materials, sound insulation materials, heat insulating materials, food packaging materials, clothing materials, building materials, and the like.

[0002]

2. Description of the Related Art Foams used for internal insulators, cushioning materials, sound insulation materials, heat insulating materials, clothing materials, building materials, etc. of electronic devices, etc., from the viewpoint of their sealing property when incorporated as parts. It is required to have characteristics such as excellent softness, cushioning property and heat insulating property. Various resin foams having such characteristics have been proposed so far.

Foam materials such as resin foams are used in various parts for the purpose of, for example, watertightness, airtightness, heat insulation, soundproofing, cushioning, etc. In some cases, the material is required to have flame retardancy, and various studies have been made on making the material flame-retardant. However, since the resin foam is composed of a thermoplastic polymer, it has a drawback that it easily burns. Therefore, it is indispensable to impart flame retardancy, especially for electronic device applications and the like.

In the foam, depending on the original material,
Generally, as a flame retardant, one or more compounds selected from chlorinated polyethylene, chlorinated paraffin, decabromodiphenyl ether, and antimony trioxide, and
A method of making flame retardant in combination with aluminum hydroxide has been widely used. However, if a chlorine-based material is used as a flame retardant, it is likely to cause corrosion due to the generation of chlorine ions from the foam, and decabromodiphenyl ether may be used due to environmental concerns due to the generation of dioxin during incineration. Considered undesirable. Also,
Antimony trioxide is an environmentally hazardous substance and a harmful substance, so its use is not desirable. Therefore, flame retardants that do not contain these compounds have been investigated. For example,
Attempts have been made to impart flame retardancy by blending metal hydroxides such as magnesium hydroxide and aluminum hydroxide, but they are inferior in flame retardance to halogen compounds used conventionally and A considerable amount of compounding amount is required to impart flame retardancy equivalent to that of the system compound,
Moldability is poor with respect to foam molding.

On the other hand, a physical foaming method and a chemical foaming method are generally used as a method of forming a foam having bubbles therein. Physical foaming is the process of impregnating a polymer with a hydrocarbon or chlorofluorocarbon low-boiling liquid and then heating the polymer to gasify the low-boiling liquid impregnated inside, and use this as the driving force to drive the polymer. Is a method of foaming. Further, the chemical foaming is a method in which a resin composition obtained by adding a thermal decomposition type foaming agent to a polymer is heated and bubbles are formed by a gas generated by decomposition of the decomposition type foaming agent. However, the technique based on physical foaming is concerned about flammability and toxicity of substances used as a foaming agent, and environmental influences such as ozone layer depletion. Further, in the chemical foaming method, the residue of the foaming gas remains in the foam, so that the contamination with corrosive gas or impurities in the gas poses a problem especially in electronic equipment applications where low contamination is highly required. In any of these physical foaming methods and chemical foaming methods, it is difficult to form a fine bubble structure, and it is said that fine bubbles of 300 μm or less cannot be formed.

In recent years, as a method for obtaining a foam having a fine cell structure, a method has been proposed in which an inert gas is dissolved in a polymer under high pressure and then the pressure is rapidly reduced to form a foam structure. For example, Japanese Unexamined Patent Publication (Kokai) No. 6-322168 discloses a method of charging a pressure vessel with a thermoplastic polymer, charging a high pressure gas while heating to the softening point of the polymer, and then reducing the pressure to form bubbles. . However, in this method, when the pressure is reduced, the polymer is in a molten state, so that the polymer is likely to expand, and the bubble diameter of the obtained foam tends to be large. Also usually
Since a polymer having a glass transition temperature of 150 ° C. or higher is used, it has low flexibility at room temperature. Therefore, when used as a soundproofing material for electronic devices, there are problems in shape conformability and cushioning properties. Further, JP-A-10-168215 discloses a method for producing a thermoplastic polyurethane foam sheet in which a sheet made of thermoplastic polyurethane is impregnated with an inorganic gas under pressure and then heated to foam. . However, these publications do not disclose or suggest any flame retardant technique.

[0007]

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a flame-retardant resin foam having high flame retardancy, high foaming and excellent flexibility, and low environmental load. It is in.

[0008]

Means for Solving the Problems The inventors of the present invention have conducted extensive studies to achieve the above-mentioned object, and as a result, when a metal hydroxide used as a flame retardant having a low environmental load was used in combination with carbon black. The flame retardancy can be greatly improved compared to the case of using only metal hydroxide as in the past, and the amount of flame retardant compounded can be reduced, and the load on the environment is reduced. Further, they have found that the fluidity of the resin at the time of foaming is secured, and as a result, a resin foam having high foaming and excellent flame retardancy and flexibility can be obtained, and the present invention was completed.

That is, the present invention is as follows.
Provided is a flame-retardant resin foam comprising the component (c). (A) Thermoplastic polymer (b) Metal hydroxide (c) Carbon black

As the metal hydroxide as the component (b), a composite metal hydroxide represented by the following formula (1) can be preferably used. m (M _a O _b ) · n (Q _d O _e ) · cH ₂ O (1) [In the above formula, M and Q are different metal elements, and Q
Is a metal element belonging to the group selected from IVa, Va, VIa, VIIa, VIII, Ib and IIb of the periodic table. m,
n, a, b, c, d, and e are positive numbers, and may have the same value or different values.]

M representing the metal element in the composite metal hydroxide represented by the above formula (1) is aluminum, magnesium, calcium, nickel, cobalt, tin, zinc,
Suitably it is at least one metal selected from the group consisting of copper, iron, titanium and boron. Further, Q, which represents the metal element in the complex metal hydroxide represented by the formula (1), is at least one metal selected from the group consisting of iron, cobalt, nickel, palladium, copper and zinc. Is preferred.

Such a flame-retardant resin foam can be formed through a step of impregnating a mixture containing the components (a) to (c) with a high-pressure inert gas and then reducing the pressure. Carbon dioxide or nitrogen is suitable as the inert gas.

In the present specification, "thermoplastic polymer" is used in a broad sense to include not only ordinary thermoplastic resins but also rubber elastomers and thermoplastic elastomers. In addition, boron (B) is also included in the metal element.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION [(A) Thermoplastic Polymer] The (A) thermoplastic polymer constituting the flame-retardant resin foam of the present invention is not particularly limited as long as it is a polymer capable of forming a foam. Examples of such a thermoplastic polymer (a) include polyolefins such as low density polyethylene, medium density polyethylene, linear polyethylene, high density polyethylene, polypropylene, ethylene or a copolymer of propylene and other α-olefin. -Based polymers; polystyrene-based polymers such as polystyrene and ABS resin; polymethylmethacrylate; polyvinyl chloride; polyvinyl fluoride; alkenyl aromatic resins; 6-nylon, 66-
Polyamides such as nylon and 12-nylon; polyesters such as polyethylene terephthalate and polybutylene terephthalate; polycarbonates such as bisphenol A-based polycarbonates; polyacetals; polyphenylene sulfides; ethylene and vinyl acetate, acrylic acid,
Acrylic ester, methacrylic acid, methacrylic acid ester, copolymers with vinyl alcohol, etc. (ethylene-based copolymers); ethylene-propylene copolymer, ethylene-
Olefin-based elastomers such as propylene-diene copolymer, ethylene-vinyl acetate copolymer, polybutene, polyisobutylene, and chlorinated polyethylene; styrene-butadiene-styrene copolymer, styrene-isoprene-
Styrene copolymers, styrene-isoprene-butadiene-styrene copolymers, styrene-based thermoplastic elastomers such as hydrogenated polymers thereof, polyester-based thermoplastic elastomers, polyurethane-based thermoplastic elastomers, acrylic-based thermoplastic elastomers, etc. Examples include thermoplastic elastomers. These thermoplastic polymers may be used alone or in admixture of two or more.

Among these, (i) a thermoplastic elastomer, (ii) a polyolefin-based polymer such as polypropylene, (iii) a rubber (elastomer) or a thermoplastic polymer containing a thermoplastic elastomer (for example, ethylene-propylene copolymer, etc.). (A mixture of the olefin elastomer of (1) and a polyolefin polymer such as polypropylene) is preferable.

[(B) Metal Hydroxide] As the (b) metal hydroxide constituting the flame-retardant resin foam of the present invention, a metal capable of releasing moisture to extinguish a flame by heating. Hydroxides can be used. As the metal element in such a metal hydroxide (b), aluminum (Al), magnesium (Mg), calcium (C
a), nickel (Ni), cobalt (Co), tin (S
n), zinc (Zn), copper (Cu), iron (Fe), titanium (Ti), boron (B) and the like. Of these, aluminum and magnesium are preferable.

The metal hydroxide (b) may be composed of one kind of metal element or may be composed of two or more kinds of metal elements. In the present invention, for example, aluminum hydroxide and magnesium hydroxide are preferably used as the metal hydroxide composed of one kind of metal element.

In the present invention, a composite metal hydroxide, which is a metal hydroxide composed of two or more kinds of metal elements, can also be preferably used. As such a composite metal hydroxide, for example, a composite metal hydroxide represented by the above formula (1) is preferable. In the complex metal hydroxide represented by the above formula (1), as the metal element M, aluminum (Al), magnesium (Mg), calcium (C
a), nickel (Ni), cobalt (Co), tin (S
n), zinc (Zn), copper (Cu), iron (Fe), titanium (Ti), boron (B) and the like. Of these, magnesium and the like are preferable. The M may be composed of one kind of metal element or may be composed of two or more kinds of metal elements.

Further, Q showing another metal element in the polyhedral composite metal hydroxide represented by the above formula (1).
Is IVa, Va, VIa, VIIa, VIII, I of the periodic table
It is a metal belonging to the group selected from b and IIb. For example, iron (Fe), cobalt (Co), nickel (N
i), palladium (Pd), copper (Cu), zinc (Zn)
Etc. Of these, nickel and zinc are preferable. The Q may be composed of one kind of metal element,
It may be composed of two or more kinds of metal elements.

The composite metal hydroxide may have a polyhedral shape or a thin flat plate shape. By using a polyhedral complex metal hydroxide, a highly foamed resin foam can be obtained. Such a complexed metal hydroxide having a polyhedral crystal shape can be produced by a known method (see JP-A-2000-53875, etc.). For example, by controlling various conditions and the like in the manufacturing process of the complexed metal hydroxide, a desired polyhedron shape in which crystal growth in the thickness direction (c-axis direction) is large in the vertical and horizontal directions, for example, a substantially dodecahedron, A composite metal hydroxide having a shape such as a substantially octahedron or a substantially tetrahedron can be obtained.

A typical representative example of the complexed metal hydroxide having the above polyhedral shape is sMgO. (1-s) N.
iO · cH ₂ O [0 <s <1, 0 <c ≦ 1], sMgO
· (1-s) ZnO · cH 2 O [0 <s <1,0 <c ≦
1], sA1 ₂ O _3. (1-s) Fe ₂ O ₃ .cH ₂ O [0
<S <1, 0 <c ≦ 3] and the like. Among these, sMgO · (1-s) Q 1 O · cH 2 O [ However, Q
¹ represents Ni or Zn, and 0 <s <1, 0 <c ≦ 1], such as complex metal hydroxide, for example, magnesium oxide / nickel oxide hydrate, magnesium oxide /
A hydrate of zinc oxide is particularly preferably used.

The average particle diameter (average particle diameter) of the metal hydroxide (b) is, for example, about 0.5 to 10 μm, preferably about 0.6 to 6 μm. The average particle size can be measured by, for example, a laser type particle size measuring device. The average particle size is 1
When it exceeds 0 μm, it becomes difficult to obtain a highly foamed resin foam.

The metal hydroxide (b) may be surface-treated. The metal hydroxide (b) can be used alone or in combination of two or more kinds.

The content of the metal hydroxide (b) is 30 to 200 with respect to 100 parts by weight of the thermoplastic polymer (a).
It is about part by weight (preferably 50 to 150 parts by weight).
If the content is too small, the flame retarding effect becomes small. On the contrary, if the content is too large, moldability is lowered and it becomes difficult to obtain a highly foamed resin foam.

[(C) Carbon Black] The (C) carbon black constituting the flame-retardant resin foam of the present invention is not particularly limited, and may be selected from those generally used for reinforcing rubber and plastic. You can choose. Examples of carbon black (C) include oil furnace black, acetylene black, thermal black, channel black, and Ketjen black. The carbon black (C) can be used alone or in combination of two or more kinds. As the carbon black (C), oil furnace black, acetylene black and Ketjen black can be preferably used.

The content of carbon black (c) is about 1 to 20 parts by weight (preferably 3 to 15 parts by weight) per 100 parts by weight of the thermoplastic polymer (a). If this content is too small, the flame retarding effect becomes small, or the amount of the metal hydroxide (b) used cannot be reduced so much. On the other hand, when the amount is too large, the moldability is lowered and it becomes difficult to obtain a highly foamed resin foam.

The ratio of carbon black (C) to metal hydroxide (B) is the former / the latter (parts by weight) = 1 /
100-20 / 100, preferably 3 / 100-15 /
It is about 100.

The flame-retardant resin foam of the present invention has the above (a)
In addition to the component, the component (b) and the component (c), an additive may be added, if necessary. The type of additive is not particularly limited, and various additives commonly used in foam molding can be used. Examples of such additives include a bubble nucleating agent, a crystal nucleating agent, a plasticizer, a lubricant, a coloring agent, an ultraviolet absorber, an antioxidant, a filler, a reinforcing agent, and an antistatic agent. The addition amount of the additive can be appropriately selected within a range that does not impair the formation of bubbles and the like, and the addition amount used for molding a thermoplastic polymer such as a usual thermoplastic elastomer can be adopted.

[Production of Flame-Retardant Resin Foam] As the method for producing the flame-retardant resin foam of the present invention, physical methods, chemical methods and the like, which are generally used for foam molding, can be adopted. A common physical method is to disperse a low boiling point liquid (foaming agent) such as chlorofluorocarbons or hydrocarbons in a polymer, and then heat it to volatilize the foaming agent to form bubbles. Further, the chemical method is a method in which cells are formed by a gas generated by thermal decomposition of a compound (foaming agent) added to a polymer base to obtain a foam. A physical method is preferable in view of recent environmental problems.

In particular, in the present invention, since a foam having a small cell diameter and a high cell density can be obtained, a method using a high-pressure inert gas as a foaming agent, for example, a mixture containing the components (a) to (c) is used. A method of forming a foam through a step of reducing the pressure after impregnating with a high-pressure inert gas is preferable.
Specifically, a gas impregnating step of impregnating a mixture containing components (a) to (c) with an inert gas under high pressure, a depressurizing step of lowering the pressure to foam the resin after the step, and, if necessary, Accordingly, there may be mentioned a method of forming through a heating step of growing bubbles by heating. In this case, a preformed unfoamed molded product may be impregnated with an inert gas, and may be inert to the mixture containing the molten thermoplastic polymer (a) (including the (b) component and the (c) component). After impregnating the gas under pressure, it may be molded during depressurization. These steps may be performed by either a batch method or a continuous method.

According to the batch method, the foam can be formed as follows, for example. That is, first, using an extruder such as a single-screw extruder or a twin-screw extruder, an unfoamed molded product (foamed product) is extruded by extruding a mixture containing a thermoplastic polymer (a) such as a polyolefin resin or a thermoplastic elastomer. A body-forming resin sheet or the like). Alternatively,
Using a kneader equipped with rollers, cams, kneaders, and Banbury-type blades, a mixture containing a thermoplastic polymer (a) such as a polyolefin resin or a thermoplastic elastomer is uniformly kneaded, and this is mixed with a hot plate. Press molding is performed using a pressing machine to form an unfoamed molded product (a resin sheet for foam molding, etc.) containing a thermoplastic polymer as a base resin. Then, the obtained unfoamed molded product is placed in a pressure resistant container, high-pressure inert gas is introduced, and the unfoamed molded product is impregnated with the inert gas. In this case, the shape of the unfoamed molded product is not particularly limited, and may be any of a roll shape, a plate shape and the like. The introduction of the high-pressure inert gas may be carried out continuously or discontinuously. When impregnated with a sufficiently high-pressure inert gas, the pressure is released (usually up to atmospheric pressure), and bubble nuclei are generated in the base resin. The bubble nuclei may be grown as it is at room temperature, or may be grown by heating if necessary. As a heating method, a known or commonly used method such as water bath, oil bath, hot roll, hot air oven, far infrared ray, near infrared ray, or microwave can be adopted. After the bubbles are grown in this way, they are rapidly cooled with cold water or the like to fix their shapes.

On the other hand, according to the continuous method, the foam can be formed as follows, for example. That is, a single screw extruder,
Using an extruder such as a twin-screw extruder, inject a high-pressure inert gas while kneading the mixture containing the thermoplastic polymer (a), sufficiently impregnate the thermoplastic polymer with the gas, and then extrude The pressure is released (usually up to atmospheric pressure), foaming and molding are performed simultaneously, and in some cases heating is performed to grow bubbles. After growing the bubbles, the shape is fixed by rapidly cooling with cold water or the like.

The inert gas is not particularly limited as long as it is inert to the thermoplastic polymer and can be impregnated therein, and examples thereof include carbon dioxide, nitrogen and air. These gases may be mixed and used. Of these, carbon dioxide and nitrogen are preferable, and particularly carbon dioxide, which has a large amount of impregnation into the thermoplastic polymer used as the material of the foam and has a high impregnation rate, is preferable.

The inert gas (such as carbon dioxide) when impregnating the thermoplastic polymer is preferably in a supercritical state. In the supercritical state, the solubility of the gas in the polymer is increased, and it is possible to mix it in a high concentration. Further, at the time of a rapid pressure drop after impregnation, since the concentration is high as described above, the generation of bubble nuclei increases, and the density of bubbles formed by the growth of the bubble nuclei is large even if the porosity is the same. Therefore, fine bubbles can be obtained. The critical temperature of carbon dioxide is 31 ° C., and the critical pressure is 7.4 MPa.

The pressure in the gas impregnation step is
For example, 6 MPa or more (for example, about 6 to 100 MPa),
It is preferably at least 8 MPa (for example, about 8 to 100 MPa). When the pressure is lower than 6 MPa, bubble growth during foaming is remarkable and the bubble diameter becomes too large. This is because when the pressure is low, the amount of gas impregnated is relatively small compared to when the pressure is high, and the number of bubble nuclei formed due to the decrease in the bubble nucleation rate decreases, so the amount of gas per bubble increases conversely. This is because the bubble diameter becomes extremely large. Also, 6MP
In the pressure region lower than a, the bubble diameter and bubble density are greatly changed only by slightly changing the impregnation pressure, so that control of the bubble diameter and bubble density tends to be difficult.

The temperature in the gas impregnation step varies depending on the type of the inert gas and the thermoplastic polymer used, and can be selected within a wide range, but in consideration of operability, it is, for example, about 10 to 350 ° C. For example, the impregnation temperature when impregnating an unfoamed molded product such as a sheet with an inert gas is about 10 to 200 ° C., preferably about 40 to 200 ° C. in the batch system. In addition, the impregnation temperature in the case of extruding a mixture containing a molten polymer impregnated with gas and performing foaming and molding at the same time is 60 to 35 in the continuous system.
A temperature of about 0 ° C is common. When carbon dioxide is used as the inert gas, in order to maintain the supercritical state,
The temperature during impregnation is preferably 32 ° C. or higher, particularly 40 ° C. or higher.

In the depressurizing step, the depressurizing speed is not particularly limited, but is preferably about 5 to 300 MPa / sec in order to obtain uniform fine bubbles. The heating temperature in the heating step is, for example, about 40 to 250 ° C,
It is preferably about 60 to 250 ° C.

The foam in the present invention can have a fine cell size having an average cell diameter of 0.1 to 300 μm, preferably 5 to 250 μm, more preferably 30 to 200 μm. The relative density (density after foaming / density in unfoamed state) is 0.3 or less (for example, 0.00
2 to 0.3), preferably 0.25 or less (for example,
About 0.005 to 0.25). Moreover, repulsive load when compressed by 50% (hereinafter sometimes referred to as "50% compressive load") is 20 N / cm ² or less (e.g., 0.1~20N / cm ² approximately), in particular 15N / cm ²
The following is preferable (for example, about 0.3 to 15 N / cm ² ). Such a foam is particularly excellent in flexibility.

The above-mentioned average cell diameter, relative density and 50% compressive load may be controlled by, for example, temperature, pressure and time in the gas impregnation step depending on the inert gas used and the type of thermoplastic polymer or thermoplastic elastomer. It can be adjusted by appropriately selecting and setting the conditions, the depressurizing rate in the depressurizing step, operating conditions such as temperature and pressure, and the heating temperature after depressurizing.

The flame-retardant resin foam thus obtained has a sufficient expansion ratio and high flexibility, probably because the fluidity of the resin is secured during foaming and the growth of bubbles is not hindered. For example, a resin foam having a relative density of about 0.01 to 0.10, preferably about 0.01 to 0.06 can be obtained. The relative density means a value calculated by the following formula. Relative density (−) = (density of foam) ÷ [density of sheet (resin molded body) before foaming]

Since (b) the metal hydroxide is used in combination with (c) carbon black, the flame retardancy can be greatly improved. For example, the amount of metal hydroxide used can be reduced. However, the reduction of the flame retardant effect is suppressed or prevented. Moreover, it is possible to foam the resin while ensuring the fluidity of the resin. Therefore, it is possible to obtain a flame-retardant resin foam which is highly foamed and has excellent flexibility.

Furthermore, the flame-retardant resin foam of the present invention has higher safety and less environmental burden than conventional foams containing only a flame retardant such as chlorine resin or antimony. .

The flame-retardant resin foam of the present invention can have a fine cell size having an average cell diameter of 0.1 to 300 μm and a relative density of 0.3 or less and 5 or less.
The repulsive load when compressed by 0% can be adjusted to be 20 N / cm ² or less, so that it is flexible and flame-retardant. It is the body. Therefore, it can be suitably used as a soundproofing material used inside an electronic device or the like.

[0044]

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. The relative density, 50% compression load, and average cell diameter of the foam were determined by the following methods.

(Relative Density) The relative density was determined by the following formula. Relative density (−) = (density of foam) / (density of sheet before foaming) (50% compression load) A plurality of test pieces cut out in a circular shape with a diameter of 30 mm are stacked to have a thickness of about 25 mm, The stress when compressed to 50% at a compression speed of 10 mm / min was converted into a unit area (cm ² ) to obtain a 50% compression load. (Average cell diameter) The foamed sheet that was created was frozen in liquid nitrogen and then cut, and the section was taken with a scanning electron microscope (SEM) (Hita
chi-570) was observed at an accelerating voltage of 10 kV, and the average bubble diameter was obtained from the obtained observed image by image processing. (Oxygen index) The oxygen index of the mixed resin before foaming was measured according to JIS K 7201. (Flame retardancy) Slices were cut into a thickness of 1 mm, and a foam combustion test was performed according to UL94 standard (HF-1) to determine flame retardancy (pass or fail).

(Example 1) Density was 0.9 g / cm ³ , 2
50 parts by weight of polypropylene having a melt flow rate of 4 at 30 ° C., 50 parts by weight of an olefin elastomer having a JIS-A hardness of 69, 10 parts by weight of carbon black produced by an oil furnace method, and MgO · Ni
Laboplast mill (manufactured by Toyo Seiki Co., Ltd.) with 100 parts by weight of polyhedral complex metal hydroxide (average particle size 0.7 μm) represented by the formula O · H ₂ O
Was kneaded at a temperature of 180 ° C., and was then molded into a sheet having a thickness of 0.5 mm and a diameter of 80 mm using a hot plate press heated to 180 ° C. Put this sheet in a pressure resistant container,
Carbon dioxide was impregnated in the atmosphere of 0 ° C. under a pressure of 15 MPa for 10 minutes. Then, the pressure was rapidly reduced to obtain a foam made of an olefin-based polymer. This foam, as shown in Table 1,
The relative density was 0.033, the average cell diameter was 83 μm, and the 50% compression load was 2.49 N / cm ² .

(Example 2) Density is 0.9 g / cm ³ , 2
30 parts by weight of polypropylene having a melt flow rate of 4 at 30 ° C., 70 parts by weight of an olefin elastomer having a JIS-A hardness of 69, 10 parts by weight of carbon black produced by an oil furnace method, and MgO · Ni
Laboplast mill (manufactured by Toyo Seiki Co., Ltd.) with 100 parts by weight of polyhedral complex metal hydroxide (average particle size 0.7 μm) represented by the formula O · H ₂ O
Was kneaded at a temperature of 180 ° C., and was then molded into a sheet having a thickness of 0.5 mm and a diameter of 80 mm using a hot plate press heated to 180 ° C. Put this sheet in a pressure resistant container,
Carbon dioxide was impregnated in the atmosphere of 0 ° C. under a pressure of 15 MPa for 10 minutes. Then, the pressure was rapidly reduced to obtain a foam made of an olefin-based polymer. This foam, as shown in Table 1,
The relative density was 0.045, the average cell diameter was 93 μm, and the 50% compression load was 1.49 N / cm ² .

(Example 3) Density is 0.9 g / cm ³ , 2
50 parts by weight of polypropylene having a melt flow rate of 4 at 30 ° C., 50 parts by weight of an olefin elastomer having a JIS-A hardness of 69, 5 parts by weight of carbon black produced by an oil furnace method, and MgO.NiO
・ 100 parts by weight of a polyhedral complex metal hydroxide (average particle size 0.7 μm) represented by the formula of H ₂ O and a Labo Plastomill equipped with roller type blades (manufactured by Toyo Seiki Seisakusho) After kneading at a temperature of 180 ° C, a hot plate press heated to 180 ° C was used to form a sheet having a thickness of 0.5 mm and a diameter of 80 mm. Put this sheet in a pressure resistant container and
Carbon dioxide was impregnated in the atmosphere at 0 ° C. under a pressure of 15 MPa for 10 minutes. Then, the pressure was rapidly reduced to obtain a foam made of an olefin-based polymer. As shown in Table 1, this foam had a relative density of 0.026, an average cell diameter of 80 μm, and a 50% compression load of 2.10 N / cm ² .

(Example 4) Density was 0.9 g / cm ³ , 2
40 parts by weight of polypropylene having a melt flow rate of 4 at 30 ° C., 60 parts by weight of an olefinic elastomer having a JIS-A hardness of 69, 10 parts by weight of carbon black produced by an oil furnace method, and MgO.Ni
120 parts by weight of a polyhedral complex metal hydroxide (average particle size: 0.7 μm) represented by the formula O · H ₂ O, and a Labo Plastomill equipped with roller type blades (manufactured by Toyo Seiki Seisakusho)
Was kneaded at a temperature of 180 ° C., and was then molded into a sheet having a thickness of 0.5 mm and a diameter of 80 mm using a hot plate press heated to 180 ° C. Put this sheet in a pressure resistant container,
Carbon dioxide was impregnated in the atmosphere of 0 ° C. under a pressure of 15 MPa for 10 minutes. Then, the pressure was rapidly reduced to obtain a foam made of an olefin-based polymer. This foam, as shown in Table 1,
The relative density was 0.045, the average cell diameter was 75 μm, and the 50% compression load was 1.45 N / cm ² .

(Comparative Example 1) Density is 0.9 g / cm ³ , 2
50 parts by weight of polypropylene having a melt flow rate of 4 at 30 ° C., 50 parts by weight of an olefin elastomer having a JIS-A hardness of 69, and a polyhedral composite metal represented by the formula MgO · NiO · H ₂ O. 110 parts by weight of hydroxide (average particle size 0.7 μm) and 180 ° C. by a Labo Plastomill (manufactured by Toyo Seiki Seisakusho) equipped with roller type blades
After kneading at the temperature of, a hot plate press heated to 180 ° C. was used to form a sheet having a thickness of 0.5 mm and a diameter of 80 mm. This sheet was placed in a pressure resistant container and kept under a pressure of 15 MPa in an atmosphere of 150 ° C. for 10 minutes to impregnate carbon dioxide. Then, the pressure was rapidly reduced to obtain a foam made of an olefin-based polymer. As shown in Table 1, this foam had a relative density of 0.046, an average cell diameter of 90 μm, and an average cell diameter of 50 μm.
The% compressive load was 3.10 N / cm ² .

(Comparative Example 2) Density is 0.9 g / cm ³ , 2
50 parts by weight of polypropylene having a melt flow rate of 4 at 30 ° C., 50 parts by weight of an olefin elastomer having a JIS-A hardness of 69, and a polyhedral composite metal represented by the formula MgO · NiO · H ₂ O. 120 parts by weight of hydroxide (average particle size 0.7 μm) and 180 ° C. by a Labo Plastomill equipped with roller type blades (manufactured by Toyo Seiki Seisakusho)
After kneading at the temperature of, a hot plate press heated to 180 ° C. was used to form a sheet having a thickness of 0.5 mm and a diameter of 80 mm. This sheet was placed in a pressure resistant container and kept under a pressure of 15 MPa in an atmosphere of 150 ° C. for 10 minutes to impregnate carbon dioxide. Then, the pressure was rapidly reduced to obtain a foam made of an olefin-based polymer. As shown in Table 1, this foam had a relative density of 0.040, an average cell diameter of 90 μm, and an average cell diameter of 50 μm.
The% compressive load was 2.95 N / cm ² .

Regarding the foams obtained in Examples 1 to 4 and Comparative Examples 1 and 2, the oxygen index (according to JIS K 7201) of the mixed resin in the mixed resin before foaming and the flame retardancy (UL94 standard ( According to HF-1))
When was evaluated, the results shown in Table 1 were obtained.

[0053]

[Table 1]

From Table 1, the resin foams of Examples corresponding to the present invention, that is, the resin foams in which the metal hydroxide and carbon black as the flame retardant are used in combination, are compared with the resin foams of Comparative Examples. It has high foaming and excellent flexibility.
Also, the relative density is small. Of course, it has excellent flame retardancy.

[0055]

The flame-retardant resin foam of the present invention has high flame retardancy, high foaming and excellent flexibility. Also, the load on the environment is small.

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI Theme Coat (reference) C08L 101/00 C08L 101/00 (72) Inventor Tomohiro Taruno 1-2-2 Shimohozumi, Ibaraki-shi, Osaka No. Nitto Denko Co., Ltd. (72) Inventor Mitsuhiro Kaneda 1-2, Shimohozumi, Ibaraki City, Osaka Prefecture F-term at Nitto Denko Co., Ltd. AA24B AA25 AA25A AA26 AA26A AA29 AA32 AA32. CC45Z CC46Z CC49Z CC55Z DA02 DA03 DA18 DA32 DA33 DA35 DA37 DA38 DA58 4J002 BB021 BB051 BB061 BB071 BB081 BB111 BB151 BB 171 BB181 BB241 BC001 BC021 BD031 BD131 BE031 BF031 BG041 BG061 BN151 BP011 CB001 CF031 CF061 CF071 CG011 CK021 CL011 CL031 CN011 DA037 DE076 DE086 DE096 DE106 DE116 DE136 DE146 DK006 GG01 GD136 FD006 GL01 FD136FD

Claims (11)

[Claims] 1. A flame-retardant resin foam containing the following components (a) to (c). (A) Thermoplastic polymer (b) Metal hydroxide (c) Carbon black 2. The metal hydroxide as the component (b) is a complex metal hydroxide represented by the following formula (1).
The flame-retardant resin foam described. m (M _a O _b ) · n (Q _d O _e ) · cH ₂ O (1) [In the above formula, M and Q are different metal elements, and Q
Is a metal element belonging to the group selected from IVa, Va, VIa, VIIa, VIII, Ib and IIb of the periodic table. m,
n, a, b, c, d, and e are positive numbers, and may have the same value or different values.] 3. M representing the metal element in the composite metal hydroxide represented by the formula (1) is aluminum, magnesium, calcium, nickel, cobalt, tin, zinc,
The flame-retardant resin foam according to claim 2, which is at least one metal selected from the group consisting of copper, iron, titanium and boron. 4. A metal element Q in the complex metal hydroxide represented by formula (1), wherein Q is at least one metal selected from the group consisting of iron, cobalt, nickel, palladium, copper and zinc. The flame-retardant resin foam according to claim 2 or 3. 5. The flame-retardant resin foam according to claim 2, wherein the composite metal hydroxide represented by the formula (1) has an average particle diameter of 0.5 to 10 μm. . 6. A foam formed by a step of impregnating a mixture containing components (a) to (c) with a high-pressure inert gas and then depressurizing the mixture. A flame-retardant resin foam according to item. 7. The flame-retardant resin foam according to claim 6, wherein the inert gas is carbon dioxide or nitrogen. 8. The flame-retardant resin foam according to claim 6, wherein the inert gas at the time of impregnation is in a supercritical state. 9. The flame-retardant resin foam according to claim 1, which has an average cell diameter of 0.1 to 300 μm and a relative density of 0.3 or less. 10. The repulsive load when compressed by 50% is 20.
The flame-retardant resin foam according to any one of claims 1 to 9, which has a N / cm ² or less. 11. The thermoplastic polymer as the component (a) is a polymer selected from (i) a thermoplastic elastomer, (ii) a polyolefin-based polymer, and (iii) a thermoplastic polymer containing a rubber or a thermoplastic elastomer. The flame-retardant resin foam according to any one of claims 1 to 10.