JP2002128932A - Rubber-based, flame-retardant foam - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an EPDM-based vulcanized foam which is halogen-free and exhibits high flame retardancy. SOLUTION: The rubber-based flame-retardant foam is composed of a vulcanized foam of an EPDM, contains an expandable graphite and a hydrated metal compound, and is halogen-free. The expandable graphite expands in combustion to form an expandable char layer thereby exhibiting effects of heat insulation and shut-off of oxygen, and the hydrated metal compound not only exhibits a flame-retardant effect by an endothermic action but also enhances the char layer thereby to improve effects of suppression of falling of kindling agent and prevention of continuation of combustion to exhibit high flame-retardant effects. Thus, the EPDM-based foam excellent in cushioning properties, compression properties and the like, halogen-free and low toxic can be formed, and a low-density foam is also easily formed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an EPDM rubber-based flame-retardant foam comprising a halogen-free, highly flame-retardant vulcanized foam.

[0002]

2. Description of the Related Art Conventionally, EPDM flame-retardant vulcanized foams include one or more halogenated compounds such as chlorinated polyethylene, chlorinated paraffin, decabromodiphenyl ether and the like and antimony trioxide and aluminum hydroxide. Which have been provided with flame retardancy by using a combination thereof. Such foams are widely used in various fields as various sealing materials such as airtightness and water stoppage, or heat insulating materials, soundproofing materials, cushioning materials, etc. based on their excellent cushioning properties and compressibility. However, halogen-based compounds have a problem that they generate halogen-based gas that exhibits toxicity and corrosiveness during combustion and induce dioxin during incineration, and that antimony trioxide is also a harmful substance, and is liable to be accompanied by environmental pollution.

[0003]

An object of the present invention is to develop an EPDM vulcanized foam which is halogen-free and exhibits high flame retardancy.

[0004]

The present invention provides a rubber-based flame-retardant foam comprising a vulcanized foam of EPDM, containing expandable graphite and a hydrated metal compound and being halogen-free. It is.

[0005]

According to the present invention, the expandable graphite expands during combustion to form a foamable char layer, thereby exhibiting an adiabatic effect and an oxygen barrier effect, and the hydrated metal compound increases the temperature before combustion. Sometimes exhibits an endothermic effect at a high temperature such as around 300 ° C. and exhibits a flame retardant effect of delaying combustion, and the hydrated metal compound reinforces and reinforces the expandable char layer made of the expandable graphite described above, whereby The formation of a strong foamable char layer and the dropping of a kind of fire are suppressed, and the effect of preventing the continuation of combustion by the above-mentioned oxygen blocking effect is improved.

As a result, a high degree of flame retardant effect is exhibited by using expandable graphite and a hydrated metal compound in combination. By the way, when the expandable graphite is used alone, the strength of the foamable char layer to be formed is weak and the flame burning time and remnants are long, and even when the hydrated metal compound is used alone, the flame burning time is long and the HF of UL94 combustion standard is used. -1 cannot be obtained. Therefore, according to the present invention, a low-toxic EPDM foam showing halogen-free and high flame retardancy while preserving the properties such as cushioning and compressibility due to the rubber properties of the EPDM vulcanized foam is excellent. It can be formed, and it is easy to form a low-density foam.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION A rubber-based flame-retardant foam according to the present invention comprises:
It is made of a vulcanized EPDM foam and contains an expandable graphite and a hydrated metal compound and is halogen-free. Such a rubber-based flame-retardant foam is formed by adding expandable graphite and a hydrated metal compound as a flame retardant to a usual compounding component such as EPDM or a vulcanizing agent or a foaming agent for forming an EPDM vulcanized foam. In addition, an admixture can be formed, and the rubber-based flame-retardant foamed composition can be vulcanized and foamed.

In the above, E as the base of the vulcanized foam is used.
As the PDM, one or more appropriate ethylene-propylene-diene rubbers can be used, and the type is not particularly limited. The Mooney viscosity (ML) is better than the adjustability and miscibility of performance such as compressibility due to rubber properties.
_{1 + 4} , 100 ° C) 5 to 30, especially 8 to 25 EPD
M can be preferably used.

The vulcanizing agent for vulcanizing EPDM is not particularly limited, and one or more suitable vulcanizing agents can be used. By the way, examples include sulfur and sulfur compounds, selenium and magnesium oxide, lead monoxide and zinc oxide,
Organic peroxides and polyamines, oximes such as P-quinone dioxime and P, P'-dibenzoylquinone dioxime, nitroso compounds such as P-dinitrosobenzine, alkylphenol-formaldehyde resin, melamine-formaldehyde condensation And ammonium salts such as ammonium benzoate.

Sulfur and sulfur compounds, especially sulfur, can be preferably used from the viewpoint of physical properties such as durability due to vulcanizability and foamability of the obtained foam. The amount of the vulcanizing agent can be appropriately determined according to the vulcanizing efficiency based on the type of the vulcanizing agent. By the way, in the case of sulfur, 0.1 to 10 parts by weight, especially 0.5 to 5 parts by weight is used per 100 parts by weight of EPDM.

As the foaming agent for forming the foam, one or more suitable foaming agents can be used, and there is no particular limitation. Incidentally, examples thereof include inorganic foaming agents such as ammonium carbonate and ammonium hydrogen carbonate, sodium hydrogen carbonate and ammonium nitrite, sodium borohydride and azides.

Also, azo compounds such as azobisisobutyronitrile, azodicarboxylic amide (ADCA) and barium azodicarboxylate, paratoluenesulfonyl hydrazide, diphenylsulfone-3,3'-disulfonyl hydrazide, 4,4 Organic blowing agents such as hydrazine compounds such as' -oxybis (benzenesulfonylhydrazide) and allylbis (sulfonylhydrazide) are also included.

Further, semicarbazide compounds such as ρ-toluylenesulfonyl semicarbazide and 4,4′-oxybis (benzenesulfonyl semicarbazide), triazole compounds such as 5-morpholyl-1,2,3,4-thiatriazole; Organic foaming agents such as N-nitroso-based compounds such as N'-dinitrosopentamethylenetetramine and N, N'-dimethyl-N, N'-dinitrosoterephthalamide are also included.

The foaming agent used may be heat-expandable fine particles in which a heat-expandable substance is encapsulated in microcapsules. The heat-expandable fine particles include commercially available products such as microspheres (trade name, manufactured by Matsumoto Yushi Co., Ltd.). The amount of the foaming agent can be appropriately determined according to the physical properties of the desired foam. Generally, 0.1 to 100 parts by weight, especially 0.5 to 50 parts by weight, especially 1 to 30 parts by weight, of a blowing agent is used per 100 parts by weight of EPDM.

As a flame retardant for flame retarding an EPDM vulcanized foam, expandable graphite and a hydrated metal compound are used in combination. This makes it possible to impart a high degree of flame retardancy by avoiding the use of a halogen-based or antimony-based flame retardant, and to obtain a halogen-free vulcanized foam while reducing toxicity and improving environmental friendliness. The blending amounts of the expandable graphite and the hydrated metal compound can be appropriately determined according to the processability of the mixture, the desired degree of flame retardation of the vulcanized foam, and the like.

In general, since the expandable graphite has a large particle size, if the compounding amount is too large, it is difficult to control the cell diameter of the foam to be small during the foaming treatment, and the foaming ratio tends to decrease. Therefore, from the viewpoint of controllability of the cell diameter and the expansion ratio, the compounding amount of the expandable graphite is 3 to 150 parts by weight, preferably 5 to 130 parts by weight, particularly 1 to 100 parts by weight of EPDM.
It is preferably from 0 to 120 parts by weight.

On the other hand, if the amount of the hydrated metal compound is too large, the foaming ratio tends to decrease, and the vulcanized foam to be formed is hard and the texture tends to be impaired. Therefore, from the viewpoint of such controllability of expansion ratio and improvement of texture, the blending amount of the hydrated metal compound is 30 to 200 parts by weight, preferably 40 to 180 parts by weight, particularly 50 to 150 parts by weight, per 100 parts by weight of EPDM. It is preferable to use a part. In addition, as the hydrated metal compound,
For example, one or more appropriate hydrous metal compounds such as aluminum hydroxide and magnesium hydroxide can be used.

The rubber-based flame-retardant foam composition is prepared by mixing at least a compounding component comprising EPDM, a vulcanizing agent, a foaming agent and the above-mentioned expandable graphite as a flame retardant and a hydrated metal compound, for example, with a kneader or a mixing roll. And mixing by an appropriate method such as a method of mixing through a kneader to obtain an admixture. At this time, a mixing method in which the temperature is raised to such an extent that vulcanization proceeds is not preferable.

In preparing the above-mentioned admixture, an appropriate compounding agent similar to the conventional one is used for the purpose of adjusting the moldability and vulcanizability by viscosity and the like, and adjusting the physical properties such as the strength of the obtained vulcanized foam. Can be added. Incidentally, a softener can be blended for the purpose of improving moldability or workability.
One or more suitable softening agents can be used, and there is no particular limitation.

Examples of the softening agent include paraffins, waxes, naphthenes, aromas, asphalts, drying oils such as linseed oil, animal and vegetable oils, petroleum oils, various low-polymers, and phthalates. Examples thereof include acid esters, phosphoric esters, stearic acid and esters thereof, alkylsulfonic acid esters, and tackifiers. The blending amount of the softening agent is appropriately determined depending on the physical properties of the vulcanized foam to be aimed, but generally 10 to 10 parts by weight of EPDM per 100 parts by weight of EPDM in view of rubber physical properties, low toxicity, low density and miscibility. 100 parts by weight, especially 15 to 80 parts by weight, especially 2
0 to 60 parts by weight.

For the purpose of accelerating vulcanization, the admixture comprises, for example, guanidines, thiazoles, sulfenamides, turams, dithiocarbamic acids, xanthogenic acids, aldehyde ammonias, aldehyde amines, thioureas, and the like. One or two or more vulcanization accelerators, and further a vulcanization accelerator may be added. The amount of the vulcanization accelerator used is 0.1% per 100 parts by weight of EPDM.
1 to 10 parts by weight is suitable, but not limited thereto.

The admixture may further contain an organic acid such as phthalic anhydride, benzoic acid or salicylic acid, or an amine such as N-nitroso-diphenylamine or N-nitroso-phenyl-β-naphthylamine, for the purpose of controlling the moldability with time. It is also possible to blend one or more vulcanization retarders, such as a vulcanizing agent, to retard vulcanization, contrary to the vulcanization accelerators described above.

In addition, urea-based, salicylic-acid and benzoic acid-based foaming aids, talc and calcium carbonate, clay and mica powder, zinc oxide and bentonite, carbon black and silica, alumina and aluminum silicate, acetylene Add one or more additives as needed, excluding conventional flame retardants such as fillers such as black and aluminum powder, antioxidants, antioxidants and pigments, coloring agents and fungicides, etc. can do. The above-mentioned stearic acid and its esters are useful as lubricants, zinc oxide is also useful as a stabilizer, and carbon black is also useful as a reinforcing agent. Therefore, examples of components that can also contain various lubricants, stabilizers and reinforcing agents are included. As

Further, the admixture may contain one or more non-rubber polymers or rubber polymers other than EPDM for the purpose of controlling physical properties such as the strength of the obtained vulcanized foam. . As the non-rubber-based polymer or rubber-based polymer, an appropriate one can be used, and there is no particular limitation. Incidentally, examples of the non-rubber-based polymer include acrylic polymers such as alkyl poly (meth) acrylate, urethane-based polymers, polyethylene and polypropylene, ethylene-vinyl acetate copolymer and polyvinyl acetate, polyamide, polyester, and styrene. Polymer, silicone polymer, epoxy resin and the like. The amount of EPDM used is preferably 50% by weight or less, more preferably 30% by weight or less, and particularly preferably 15% by weight or less, for maintaining the rubber-like properties of the vulcanized foam.

On the other hand, examples of rubber-based polymers other than the above-mentioned EPDM include α-olefins such as butene-1.
A rubber-based copolymer or ethylene-propylene rubber containing a cyclic or acyclic polyene having a nonconjugated double bond such as dicyclopentadiene or ethylidene norbornene,
Ethylene-propylene terpolymer, silicone rubber,
Polyurethane rubber, polyamide rubber, natural rubber, polyisobutylene, polyisoprene, butyl rubber, nitrile butyl rubber, styrene / butadiene rubber, styrene /
Examples include butadiene / styrene rubber, styrene / isoprene / styrene rubber, styrene / ethylene / butadiene rubber, styrene / ethylene / butylene / styrene rubber, styrene / isoprene / propylene / styrene rubber and acrylic rubber. The amount of the rubber-based polymer other than EPDM can be the same as in the case of the non-rubber-based polymer.

In the preparation of the rubber-based flame-retardant foamed composition comprising the admixture described above, it is preferable to avoid the use of a halogen-containing compound in the compounding component from the viewpoint of achieving halogen-free. The rubber-based flame-retardant foamed composition can be formed by heating the rubber-based flame-retardant foamed composition and subjecting it to vulcanization-foaming treatment. , And heat-treating the molded body to obtain a vulcanized foam. In that case, the molded body may be formed into an arbitrary form by an appropriate method, and the form is not particularly limited.

Therefore, the object of the vulcanization / foaming treatment may be a rubber-based flame-retardant foamed composition formed into a sheet or other form by an appropriate method such as a mixing roll, a calender roll, or extrusion molding. Alternatively, it may be formed into a predetermined form having irregularities or the like by an appropriate method such as injection molding or press molding through a predetermined mold.

In the above, in the formation of the vulcanized foam having an uneven shape, an unvulcanized sheet is placed on a mold having unevenness and heated, and a rubber is formed on the unevenness of the mold to form the unvulcanized sheet. It is also possible to employ a system in which a system-based flame-retardant foam composition is allowed to flow and vulcanized and foamed. Such a method has an advantage that the uneven shape can be accurately formed even in the case of a mold having a complicated and deep uneven structure having a fold structure.

Accordingly, the size of the molded article is arbitrary, and can be appropriately determined according to the desired form of the vulcanized foam. In the case of a sheet or the like, the thickness is 100 mm or less,
In particular, 1 μm to 80 mm, especially 10 μm to 50 mm is common.

The above-mentioned vulcanization / foaming treatment can be carried out under appropriate conditions according to the prior art, depending on the vulcanization starting temperature and the foaming temperature of the used vulcanizing agent or foaming agent. General vulcanization foaming temperature is 450 ° C or less, especially 100-350 ° C,
Particularly, it is 120 to 300 ° C. In general, the vulcanization and foaming treatment softens the rubber-based flame-retardant foaming composition, expands the foaming agent and forms a foamed structure, and vulcanization proceeds to form a desired vulcanized foam.

In the above, the foaming treatment and the vulcanization treatment can be performed under different temperature conditions, and appropriate treatment conditions can be adopted. The vulcanization / foaming treatment can also be performed under pressure for the purpose of adjusting the expansion ratio. The pressurization condition is
It can be according to the conventional. The expansion ratio (density ratio before and after foaming) of the vulcanized foam to be formed is appropriately determined depending on the purpose of use and the like, but is generally 1.1 to 25 times, especially 1.
It is 5 times or more, especially 5 to 20 times.

The rubber-based flame-retardant foam (vulcanized foam) which can be preferably used as a sealing material or the like is 0.01 to 0.5 g /
It has been vulcanized and foamed to have a density of cm ³ , especially 0.05 to 0.2 g / cm ³ . The density can be adjusted by the above-mentioned expansion ratio or the like, and the expansion ratio can be controlled by the compounding amount of the above-mentioned blowing agent, the processing time and temperature of vulcanization and expansion, and the like. It is also possible to control the foaming structure such as independent or continuous vulcanized foam obtained by adjusting the expansion ratio or the like, or a mixture thereof.

The rubber-based flame-retardant foam according to the present invention can be used as a sealing material for various purposes such as airtightness and waterproofing, a cushioning material and a padding material, a heat insulating material, a vibration reducing material such as soundproofing and vibration damping, etc. It can be preferably used in various fields such as indoor products, outdoor products such as automobiles, buildings such as houses, etc. for various conventional applications.

[0034]

EXAMPLES Example 1 100 parts (parts by weight, hereinafter the same) of EPDM (manufactured by Mitsui Chemicals, Inc., EPT4201), expandable graphite (manufactured by Tosoh Corporation, GR)
EP-EG) 30 parts, 100 parts of magnesium hydroxide, 10 parts of carbon, 5 parts of lead oxide, 3 parts of stearic acid, 35 parts of process oil, and 1 part of polyethylene glycol were kneaded with a Banbury mixer, and sulfur was added to the kneaded material. 1.5
Parts, 1.2 parts of a dithioate-based vulcanization accelerator, 1 part of a thiazole-based vulcanization accelerator, 20 parts of ADCA, and 5 parts of a urea-based foaming aid, and the mixture was further kneaded with a mixing roll to obtain an admixture.
It is formed into an unvulcanized unfoamed sheet having a predetermined thickness by an extruder, and then heated at 160 ° C. for 20 minutes for vulcanization and foaming treatment.
A foam sheet in which open cells and closed cells were mixed was obtained, and a skin layer on the surface was sliced to obtain a rubber-based flame-retardant foam having a density of 0.09 g / cm ³ and a thickness of 2 mm.

Comparative Example 1 The density was 0.10 according to Example 1, except that the amount of expandable graphite was changed to 100 parts without adding magnesium hydroxide.
g / cm ³ of a rubber-based flame-retardant foam was obtained.

Comparative Example 2 The density was 0.08 according to Example 1 except that the amount of magnesium hydroxide was changed to 121 parts without adding the expandable graphite.
g / cm ³ of a rubber-based flame-retardant foam was obtained.

Evaluation Test The rubber-based flame-retardant foams obtained in Examples and Comparative Examples were subjected to UL.
An HBF flame retardancy test based on the 94 standard was performed to evaluate whether or not it complies with the HF-1 grade. The results are shown in the following table.

[0038]

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 4F074 AA25 AA76 AC02 AC17 AC19 AD05 AD09 AD13 BA13 BA29 BB05 BB06 CA29 CD08 DA02 DA18 4J002 BB151 BP021 DA026 DE077 DE147 FD020 FD130 FD140 FD320 GJ02 GL00 GN00 GQ00 GR00

Claims (3)

[Claims] 1. A rubber-based flame-retardant foam comprising a vulcanized foam of EPDM, containing expandable graphite and a hydrated metal compound and being halogen-free. 2. The method according to claim 1, wherein 3 to 150 parts by weight of the expandable graphite and 30 to 200 parts by weight per 100 parts by weight of EPDM.
Rubber flame-retardant foam containing parts by weight of hydrated metal compound. 3. The method according to claim 1, wherein the density is 0.0
A rubber-based flame-retardant foam having a weight of 1 to 0.5 g / cm ³ .