JP2009249389A - Magnesium hydroxide flame retardant and flame-retardant polymer composition - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a magnesium hydroxide flame retardant being excellent in flame retardancy and capable of being easily dispersed in a polymer such as a resin and a rubber. <P>SOLUTION: (A) magnesium hydroxide having a BET specific surface area of less than 10 m<SP>2</SP>/g and an average primary particle diameter of 0.5 μm or more and (B) magnesium hydroxide being subjected to surface treatment by a lipophilic surface treating agent, having a BET specific surface area of 10 m<SP>2</SP>/g or more, having a BET specific surface area 2.5 times or more of the BET specific surface area of magnesium hydroxide (A) and having an average primary particle diameter of 0.4 μm or less are mixed such that a weight ratio (magnesium hydroxide (A)/magnesium hydroxide (B)) becomes 10/90-70/30. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a magnesium hydroxide flame retardant and a flame retardant polymer composition containing the same.

  As hydroxide-based flame retardants, aluminum hydroxide and magnesium hydroxide are mainly used. Other hydroxides include zinc hydroxide, cerium hydroxide, iron hydroxide, copper hydroxide, titanium hydroxide, barium hydroxide, beryllium hydroxide, manganese hydroxide, calcium hydroxide, strontium hydroxide, Examples include metal hydroxides selected from zirconium hydroxide and gallium hydroxide. Aluminum hydroxide and magnesium hydroxide are suitable as flame retardants because of their dehydration temperature, amount of heat absorbed during combustion, and price. .

Aluminum hydroxide (Al (OH) ₃ ) is widely used because it is rich in structural water and not only has excellent flame retardancy but also has excellent acid resistance and alkali resistance and is advantageous in terms of cost. Regarding the flame retardant properties of this aluminum hydroxide, it is known that dehydration starts gradually from about 200 ° C. and dehydrates all at once from around 230 ° C. to 250 ° C. However, due to the low dehydration temperature, it is easy to dehydrate at the processing temperature when processing a thermoplastic resin, etc., and unevenness may occur on the surface of the resin molded product, etc. .

Magnesium hydroxide (Mg (OH) ₂ ) has a high dehydration temperature peak of about 380 ° C., and when blended with a resin, the amount of smoke generated during combustion is small and nontoxic. In addition, magnesium hydroxide particles are thermoplastic resins because they are not partly dehydrated and decomposed at the processing temperature of the resin, as seen in aluminum hydroxide particles, and foam the resin molding. The range of applicable resins such as thermosetting resins is wide.

  Magnesium hydroxide particles used as a flame retardant are generally manufactured through a hydrothermal treatment step, so that the particles are large and are easily oriented because of plate crystals. In order to use magnesium hydroxide as a flame retardant, it is necessary to uniformly disperse it in the matrix. For this reason, the particle diameter is increased to facilitate dispersion.

  However, in recent years, development of magnesium hydroxide nanoparticles having a small particle diameter has been progressed, and the results are being reported.

  For magnesium hydroxide having large particles, a method of surface-treating particles obtained by a hydrothermal reaction with silicone or the like has been proposed (Patent Document 1, etc.). In fact, most magnesium hydroxide currently used as a flame retardant is magnesium hydroxide with large particles.

  For magnesium hydroxide with small particles, a method of hydrothermally treating magnesium hydroxide using phosphate, borate, etc. to obtain fine magnesium hydroxide (Patent Document 2) or high-purity magnesium oxide A method of generating fine magnesium hydroxide by hydration (Patent Document 3) and a method of adding alkali to a magnesium chloride solution to generate particles (Patent Document 4) have been proposed.

However, there is a need for a magnesium hydroxide flame retardant that is further excellent in flame retardancy and can be easily dispersed in polymers such as resins and rubbers.
JP 2002-285162 A JP 2003-129056 A JP 2002-255544 A Japanese Patent Laid-Open No. 02-279515

  An object of the present invention is to provide a magnesium hydroxide flame retardant that is excellent in flame retardancy and can be easily dispersed in a polymer such as a resin or rubber, and a flame retardant polymer composition using the same.

In the present invention, (A) magnesium hydroxide having a BET specific surface area of less than 10 m ² / g and an average primary particle size of 0.5 μm or more, and (B) a hydroxylated surface treated with a lipophilic surface treating agent Magnesium hydroxide having a BET specific surface area of 10 m ² / g or more, 2.5 times or more of the BET specific surface area of magnesium hydroxide (A), and an average primary particle size of 0.4 μm or less Are mixed at a weight ratio (magnesium hydroxide (A) / magnesium hydroxide (B)) of 10/90 to 70/30.

  The magnesium hydroxide flame retardant of the present invention is excellent in flame retardancy and can be easily dispersed in polymers such as resins and rubbers.

  The magnesium hydroxide flame retardant of the present invention is a mixture of the above magnesium hydroxide (A) and the above magnesium hydroxide (B) in the above-mentioned predetermined ratio, thereby providing excellent flame retardancy. Is obtained. Although details of the reason why excellent flame retardancy is obtained are not clear, by mixing two types of magnesium hydroxide having different primary particle sizes, the polymer containing these magnesium hydroxides burns In this case, the magnesium hydroxide particles form a structure close to a finely packed structure, which can suppress generation of gas generated by melting and vaporization of combustion heat, and can improve flame retardancy I think that the.

BET specific surface area of magnesium hydroxide (A) is less than ^{10 m} 2 / g, more preferably, less than ^{1 m} 2 / g or more ^{10 m} 2 / g, more preferably in the range of 3~9m ² / g .

  The average primary particle diameter of magnesium hydroxide (A) is 0.5 μm or more, more preferably in the range of 0.5 to 1.5 μm, and still more preferably in the range of 0.6 to 1.0 μm.

BET specific surface area of magnesium hydroxide (B) is ^{10 m} 2 / g or more, more preferably in the range of 10~35m ² / g, more preferably in the range of 15 to 30 m ² / g.

  The average primary particle diameter of magnesium hydroxide (B) is 0.4 μm or less, more preferably in the range of 0.01 to 0.4 μm, and still more preferably in the range of 0.05 to 0.3 μm.

  By setting the BET specific surface area and average primary particle diameter of magnesium hydroxide (A) and magnesium hydroxide (B) within the above ranges, excellent flame retardancy can be obtained.

  The BET specific surface area of magnesium hydroxide (B) is a value measured in the state of magnesium hydroxide surface-treated with a lipophilic surface treatment agent. Further, the BET specific surface area of magnesium hydroxide (A) is also the BET specific surface area of the surface-treated magnesium hydroxide when it is surface-treated with a lipophilic surface treatment agent. In the case of magnesium hydroxide (B), since it is a very small particle, the BET specific surface area becomes lower by performing the surface treatment than before the surface treatment. However, in the case of magnesium hydroxide (A), the BET specific surface area is almost the same before or after the surface treatment, or slightly lower than that before the surface treatment.

  Moreover, the average primary particle diameter of magnesium hydroxide (A) and (B) can be measured by observation with a scanning electron microscope (SEM), for example, for example, the average value which measured about 100 pieces. Can be calculated as

  In the present invention, the BET specific surface area of magnesium hydroxide (B) is 2.5 times or more the BET specific surface area of magnesium hydroxide (A). By setting the BET specific surface area to 2.5 times or more, excellent flame retardancy can be obtained.

  In the present invention, magnesium hydroxide (A) and magnesium hydroxide (B) are in a weight ratio (magnesium hydroxide (A) / magnesium hydroxide (B)) of 10/90 to 70/30. So that they are mixed. By setting it within such a range, excellent flame retardancy can be obtained. The mixing ratio is preferably in the range of 20/80 to 40/60.

  In the present invention, magnesium hydroxide (B) is surface-treated with a lipophilic surface treatment agent. Magnesium hydroxide (B) has a small particle size, and thus can be easily dispersed in a polymer such as a resin or rubber by surface treatment with a lipophilic surface treatment agent.

  The surface treatment amount is preferably in the range of 0.5 to 20 parts by weight, more preferably in the range of 0.5 to 10 parts by weight with respect to 100 parts by weight of magnesium hydroxide. If the surface treatment amount is too small, it may not be possible to disperse well in the polymer. Moreover, when there is too much surface treatment amount, the dispersion state in a polymer may not improve according to a treatment amount, and it may become economically disadvantageous.

  In the present invention, those that can be used as the surface treatment agent are selected from the group consisting of higher fatty acids, anionic surfactants, phosphate esters, esters of fatty acids and polyhydric alcohols, and coupling agents. There is at least one kind. Specific examples include the following.

  Higher fatty acids having 10 or more carbon atoms such as stearic acid, erucic acid, palmitic acid, lauric acid, and behenic acid; alkali metal salts of the above higher fatty acids; sulfates of higher alcohols such as stearyl alcohol and oleyl alcohol; polyethylene glycol ethers Sulfate ester salt, amide bond sulfate ester salt, ester bond sulfate ester salt, ester bond sulfonate, amide bond sulfonate, ether bond sulfonate, ether bond alkylaryl sulfonate, ester bond alkylaryl sulfonate, amide Anionic surfactants such as bonded alkylaryl sulfonates; mono- or diesters such as orthophosphoric acid and oleyl alcohol, stearyl alcohol or a mixture thereof, and their acid forms or alkali metal salts Or phosphate esters such as amine salts; vinyltrichlorosilane, vinyltrimethoxysilane, vinyltriethoxysilane, vinyltris (βmethoxyethoxy) silane, β- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, γ-glycol Sidoxypropyltrimethoxysilane, γ-glycidoxypropylmethyldiethoxysilane, γ-glycidoxypropyltriethoxysilane, γ-methacryloxypropylmethyldimethoxysilane, γ-methacryloxypropyltrimethoxysilane, γ-methacryloxy Propylmethyldiethoxysilane, γ-methacryloxypropyltriethoxysilane, N-β (aminoethyl) γ-aminopropylmethyldimethoxysilane, N-β (aminoethyl) γ-aminopropyltrimethoxysilane, N-β ( Silane coupling of γ-aminopropyltriethoxysilane, γ-aminopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, N-phenyl-γ-aminopropyltrimethoxysilane, γ-mercaptopropyltrimethoxysilane, etc. Agents: isopropyl triisostearoyl titanate, isopropyl tris (dioctyl pyrophosphate) titanate, isopropyl tri (N-aminoethyl-aminoethyl) titanate, isopropyl tridecylbenzenesulfonyl titanate, tetraoctyl bis (ditridecyl phosphite) titanate, bis (Dioctyl pyrophosphate) oxyacetate titanate, isopropyltridodecylbenzenesulfonyl titanate, tetraisopropylbis ( Octyl phosphite) titanate, tetra (2,2-diallyloxymethyl-1-butyl) bis- (ditridecyl) phosphite titanate, bis- (dioctylpyrophosphate) ethylene titanate, isopropyl trioctanoyl titanate, isopropyl dimethacrylisostearoyl Titanate coupling agents such as titanate, isopropyl isostearoyl diacryl titanate, isopropyl tri (dioctyl phosphate) titanate, isopropyl tricumyl phenyl titanate, dicumyl phenyl oxyacetate titanate, diisostearoyl ethylene titanate; acetoalkoxyaluminum diisopropylate Aluminum coupling agents such as triphenyl phosphite, diphenyl tri Silphosphite, phenyl ditridecyl phosphite, phenyl isodecyl phosphite, tri nonylphenyl phosphite, 4,4'-butylidene-bis (3-methyl-6-t-butylphenyl) -ditridecyl phosphite Esters of fatty acids and fatty acids such as glycerol monostearate and glycerol monooleate, trilauryl thiophosphite, etc.

  Magnesium hydroxide (A) used in the present invention may be surface-treated or may not be surface-treated. However, in order to improve the dispersibility in the polymer, it is preferable that the surface is treated with a lipophilic surface treatment agent. As the surface treatment agent for magnesium hydroxide (A), the same surface treatment agent as that for magnesium hydroxide (B) can be used. The surface treatment amount can also be treated in the same range as the surface treatment amount of magnesium hydroxide (B). Naturally, the types and surface treatment amounts of the surface treatment agents for magnesium hydroxide (A) and magnesium hydroxide (B) may be different from each other.

  Since the BET specific surface area and average primary particle size of magnesium hydroxide (A) in the present invention are within the range of general magnesium hydroxide conventionally used as a flame retardant, magnesium hydroxide (A) For example, magnesium hydroxide can be used as a flame retardant generally used conventionally.

  Magnesium hydroxide (B) in the present invention has a higher BET specific surface area and a smaller average primary particle size than general magnesium hydroxide conventionally used as a flame retardant. Such magnesium hydroxide (B), for example, is produced by adding an alkali to a slurry containing magnesium salt and magnesium hydroxide seed crystals to produce aggregated particles in which primary particles of magnesium hydroxide are aggregated. It can be obtained by wet-dispersing the magnesium hydroxide aggregated particles and then surface-treating with a surface treatment agent.

  The surface of the magnesium hydroxide particles has many hydroxyl groups, and the bonds between the hydroxyl groups are strong, so the magnesium hydroxide tends to aggregate. As described above, magnesium hydroxide is generated by adding an alkali such as calcium hydroxide to a slurry containing a magnesium salt and a magnesium hydroxide seed crystal. Such magnesium hydroxide agglomerated particles are fine agglomerates of magnesium hydroxide, and are finer than magnesium hydroxide conventionally used as a flame retardant. After such magnesium hydroxide particles are wet-dispersed, they are surface treated with a surface treating agent. Thereby, it can surface-treat to a fine magnesium hydroxide particle, and can be disperse | distributed in polymers, such as resin and rubber | gum, in the state of a fine magnesium hydroxide particle.

  Aggregated magnesium hydroxide particles are generated by adding an alkali to the slurry containing the magnesium salt and the magnesium hydroxide seed crystal. Examples of the magnesium salt include a salt of magnesium ion dissolved in an aqueous solution such as seawater or bitter juice. Further, it may be a salt obtained by reacting magnesia with a mineral acid such as nitric acid, hydrochloric acid or sulfuric acid, an organic acid such as formic acid, acetic acid or propionic acid, or a mixture thereof.

  The concentration of the magnesium salt in the slurry is preferably in the range of 0.01 to 10% by weight, more preferably in the range of 0.1 to 5.0% by weight. The slurry is preferably a decarboxylated solution so that magnesium carbonate is not generated. Such a solution can be supplied to the reaction vessel, and an alkali solution can be added thereto to react the alkali. Preferably, the produced magnesium hydroxide slurry is recovered in a thickener, and a part of the slurry is fed back to the reaction vessel and circulated for use. Thus, it is preferable to use the magnesium hydroxide fed back as a seed crystal. The ratio of circulation is such that the circulation ratio of magnesium hydroxide circulated to the reaction system and magnesium hydroxide produced in the reaction system (circulated magnesium hydroxide: produced magnesium hydroxide) is in the range of 7 to 20: 1. More preferably, it is the range of 9-18: 1.

  The alkali added to the slurry may be an alkali stronger than magnesium hydroxide, such as hydroxide such as potassium hydroxide, calcium hydroxide, sodium hydroxide, lithium hydroxide, or aqueous ammonia. The amount of alkali used is preferably in the range of 90 to 120% with respect to magnesium ions, with the equivalent point being 100%.

  Examples of the apparatus for wet-dispersing the magnesium hydroxide aggregated particles include apparatuses such as roller mills, bead mills, hammer mills and other high-speed rotational impact shear pulverizers, vibration mills, planetary mills and other ball mills, and wet jet mills. . In particular, a stirring mill using a medium such as a bead mill, a ball mill, or a sand mill is preferably used. As the medium, alumina, zirconia, glass, or the like can be used. In particular, it is preferable to use zirconia having an average particle diameter of 0.001 to 5.0 mm as a medium.

  As the solvent, an aqueous system is preferably used, but it is not limited to an aqueous system and can be well dispersed even when an organic solvent is used. Moreover, you may use a dispersion medium etc. together at the time of dispersion | distribution.

  The magnesium hydroxide particles after the wet dispersion are surface treated with a surface treating agent. The surface treatment method may be a wet method or a dry method. For example, as a wet method, it is preferable to add a surface treatment agent in a liquid or emulsion state to a slurry of magnesium hydroxide particles and mechanically sufficiently mix it at a temperature up to about 100 ° C.

  Also, as a dry method, the magnesium hydroxide slurry is dried to a powder, and the powdered magnesium hydroxide particles are sufficiently stirred with a mixer such as a Henschel mixer while the surface treatment agent is in a liquid, emulsion form. Or in a solid state, and may be sufficiently mixed under heating or non-heating. As described above, the treatment amount of the surface treatment agent is preferably 0.5 to 20 parts by weight, more preferably 0.5 to 10 parts by weight with respect to 100 parts by weight of the magnesium hydroxide particles. is there.

  The surface-treated magnesium hydroxide particles can be made into a final product form, for example, by washing with water, dehydration, granulation, drying, pulverization, classification and the like.

  The flame retardant polymer composition of the present invention is characterized in that the magnesium hydroxide flame retardant of the present invention is contained in a resin or rubber.

  As a compounding quantity, it is preferable that it is the range of 1-200 weight part with respect to 100 weight part of resin or rubber | gum, More preferably, it is 67-150 weight part.

  Specific examples of resins and rubbers to be blended include polyethylene, polypropylene, polybutene-1, poly-4-methylpentene, ethylene / propylene copolymer, ethylene / butene-1 copolymer, and ethylene / 4-methylpentene copolymer. , Olefin polymer or copolymer such as propylene / butene-1 copolymer, propylene / 4-methylpentene-1 copolymer, ethylene / acrylic acid ester copolymer, ethylene / propylene / diene copolymer, etc. Polymer; Copolymer or copolymer of styrene such as polystyrene, ABS, AA, AES, AS, etc .; Vinyl chloride resin, vinyl acetate resin, vinylidene chloride resin, ethylene / vinyl chloride copolymer, ethylene / vinyl acetate copolymer Vinyl chloride, vinyl acetate polymers or copolymers such as polymers; phenoxy resins, Tadiene resin, fluorine resin, polyacetal resin, polyamide resin, polyurethane resin, polyester resin, polycarbonate resin, polyketone resin, methacrylic resin, diallyl phthalate resin, phenol resin, epoxy resin, melamine resin, urea resin, SBR, BR, CR, Examples thereof include rubbers such as CPE, CSM, NBR, IR, IIR, and fluororubber.

  Moreover, it is preferable to mix | blend with a thermoplastic resin in a synthetic resin. By mix | blending with a thermoplastic resin, the flame retardance effect by a magnesium hydroxide particle, the thermal deterioration prevention effect, and the effect of mechanical strength maintenance can be acquired.

  Specific examples of the thermoplastic resin include polypropylene resins such as polypropylene homopolymer and ethylene propylene copolymer, high density polyethylene, low density polyethylene, linear low density polyethylene, ultra low density polyethylene, EVA (ethylene vinyl acetate). Resin), EEA (ethylene ethyl acrylate resin), EMA (ethylene / methyl acrylate copolymer resin), EAA (ethylene / acrylic acid copolymer resin), polyethylene resin such as ultrahigh molecular weight polyethylene, and polybutene, poly 4 -Polymers or copolymers of C2-C6 olefins (α-ethylene) such as methylpentene-1. Polyesters such as PET and PBT can also be mentioned.

  Examples of the thermosetting resin include an epoxy resin, a phenol resin, a melamine resin, an unsaturated polyester resin, an alkyd resin, and a urea resin. In general, many thermosetting resins themselves have high flame retardancy, and the resin processing temperature is higher than that of a thermoplastic resin, so that magnesium hydroxide may not be used.

  Examples of the synthetic rubber include synthetic rubbers such as EPDM, butyl rubber, isoprene rubber, SBR, NBR, chlorosulfonated polyethylene, NIR, urethane rubber, butadiene rubber, acrylic rubber, silicone rubber, and fluorine rubber.

  In addition, in the flame retardant polymer composition of the present invention, a flame retardant aid may be added. The flame retardant aid is preferably a phosphorus compound, carbon powder, or a mixture thereof. As the phosphorus compound, any substance containing phosphorus as a component, such as red phosphorus or phosphate ester, can be used. As the carbon powder, activated carbon, graphite, or carbon black can be used. Besides these, pentaerythritol, antimony trioxide and the like can be used. However, these substances are preferably not included in the resin composition in view of recent environmental problems.

  Further, by using calcium carbonate, silica, alumina, talc or the like as a flame retardant aid other than the above, it is also possible to add it for the purpose of forming a finely packed structure during resin combustion.

  The blending amount of the flame retardant aid is preferably 0.5 to 30 parts by weight, more preferably 1 to 20 parts by weight with respect to 100 parts by weight of the resin or rubber.

  Moreover, you may add antioxidant, a copper damage inhibitor, a plasticizer, etc. to the flame-retardant polymer composition of this invention.

  The same flame retardant effect can be obtained for molded products using the flame retardant polymer composition of the present invention. As molded products, used for wire covering materials, cables, sheath materials, building materials, resin parts of artificial marble and electrical appliances, sealing materials such as semiconductor elements, fibers (fiber processed products), paints, adhesives, etc. Can do.

  The magnesium hydroxide flame retardant of the present invention may be prepared by mixing magnesium hydroxide (A) and magnesium hydroxide (B) in advance before adding to a polymer or the like, and adding this mixture to the polymer or the like. Magnesium (A) and magnesium hydroxide (B) may be separately added to a polymer or the like, and magnesium hydroxide (A) and magnesium hydroxide (B) may be mixed in the polymer or the like.

  As a method of mixing the flame retardant before adding it to a polymer, etc., using a Henschel mixer or the like, magnesium hydroxide (A) and magnesium hydroxide (B) are weighed in a predetermined amount and mixed in a batch manner. Alternatively, a method of mixing by continuously passing through a mixer or a pulverizer may be used. Moreover, you may process with a surface treating agent etc. after mixing.

  According to this invention, it can be set as the magnesium hydroxide flame retardant which is excellent in a flame retardance and can be easily disperse | distributed in polymers, such as resin and rubber | gum.

  Moreover, the flame retardant polymer composition of the present invention has excellent flame retardancy.

  Hereinafter, the present invention will be described with reference to specific examples, but the present invention is not limited to the following examples.

[Preparation of magnesium hydroxide B1]
As magnesium hydroxide (B) in the present invention, magnesium hydroxide B1 was prepared as follows.

Decarboxylated seawater containing 0.12% by weight of magnesium ions was introduced into a 40 liter reaction vessel equipped with a stirrer and a pH meter at a rate of 80 liters / hour. Into this reaction vessel, an alkali solution prepared so that Ca (OH) ₂ was 5% by weight was introduced at a rate of 6 liters / hour so as to be 95% equivalent to magnesium ions.

  This reaction solution was recovered in a 230 liter thickener, and a part of the concentrated magnesium hydroxide solution was returned to the reaction vessel and circulated. The circulation ratio was 12.3: 1, and the solid content concentration in the reaction system was 6.0% by weight. Here, the circulation ratio is the weight ratio of magnesium hydroxide circulated to the reaction system and magnesium hydroxide produced in the reaction system.

  Magnesium hydroxide was extracted from the thickener and washed with 15 times the amount of decarbonated fresh water to prepare a magnesium hydroxide raw material slurry.

  This magnesium hydroxide raw material slurry is placed in a 40 liter container, the concentration is adjusted to 20% by weight in 20 liters, 20 kg of zirconia balls having a diameter of 2 mm are added, and the rotational speed is 800 rpm for 20 minutes. Stir and wet disperse.

  Thereafter, the zirconia balls were removed, and the obtained magnesium hydroxide dispersion slurry was heated to 80 ° C. Then, heat-melted oleic acid and phosphoric acid ester are added to 100 parts by weight of magnesium hydroxide so as to be 5 parts by weight, respectively, and stirred for 30 minutes. Surface treated.

  Thereafter, dehydration, drying and pulverization were performed to obtain magnesium hydroxide B1.

  In addition, polyoxyethylene alkyl ether phosphoric acid was used as phosphate ester.

The obtained magnesium hydroxide B1 had a BET specific surface area of 25.0 m ² / g and an average primary particle size of 0.2 μm.

[Preparation of magnesium hydroxide B2]
In the preparation of the above magnesium hydroxide B1, the obtained magnesium hydroxide raw material slurry was wet-dispersed, then pure water was added to prepare a 5-liter dispersed slurry, and this was stirred at 150 ° C. under stirring in an autoclave. Magnesium hydroxide B2 was obtained in the same manner except that hydrothermal treatment was performed for 3 hours and then surface treatment was performed.

The obtained magnesium hydroxide B2 had a BET specific surface area of 16.0 m ² / g and an average primary particle size of 0.3 μm.

[Magnesium hydroxide A1 and A2]
Magnesium hydroxide A1 and magnesium hydroxide A2 were used as magnesium hydroxide (A) in the present invention.

Magnesium hydroxide A1 is a commercially available magnesium hydroxide for flame retardant (manufactured by Kyowa Chemical Industry Co., Ltd., trade name “Kisuma 5AL”, higher fatty acid surface-treated product), BET specific surface area is 6.2 m ² / g, average The primary particle size is 0.8 μm.

Magnesium hydroxide A2 is a commercially available magnesium hydroxide for flame retardant (Kyowa Chemical Industry, trade name “Kisuma 5B”, higher fatty acid surface-treated product), BET specific surface area is 5.0 m ² / g, average The primary particle size is 0.8 μm.

(Examples 1-2 and Comparative Examples 1-3)
Here, magnesium hydroxide A1 was used as magnesium hydroxide (A), and magnesium hydroxide B1 was used as magnesium hydroxide (B).

  In Example 1, magnesium hydroxide A1 and magnesium hydroxide B1 were mixed and used at a weight ratio of 20/80.

  In Example 2, magnesium hydroxide A1 and magnesium hydroxide B1 were mixed and used at a ratio of 40/60.

  In Comparative Example 1, only magnesium hydroxide A1 was used.

  In Comparative Example 2, only magnesium hydroxide B1 was used.

  In Comparative Example 3, a resin composition was prepared without adding magnesium hydroxide.

(Preparation of resin composition)
Using a twin-screw extruder, magnesium hydroxide was blended into the polyethylene resin so that the blending ratio of magnesium hydroxide was 40% by weight to prepare a compound. From the compound, test pieces for various tests were prepared and evaluated using an injection molding machine. For Comparative Example 3, a compound was prepared without adding magnesium hydroxide, and a test piece was prepared using the compound.

  Compound processing conditions and molding processing conditions are shown below.

(1) Compound: Equipment: TOSHIBA MACHINE CO., LTD.
TEM-35B (φ: 37mm L / D: 31.9)
Temperature: 210 ° C. to 195 ° C., screw rotation speed: 300 rpm,
Discharge rate: 20.079 kg / h
(2) Molding: Equipment: TOSHIBA MACHINE CO., LTD. Injection molding machine IS 30EPN-1A
Temperature: 220 ° C., injection pressure: 1854 kgf / cm ²
Injection speed: 33.6 cm ³ / sec, mold clamping force: 28 ton

[Evaluation of resin composition]
The obtained resin composition was subjected to oxygen index measurement, tensile test, and bending test as follows.

(1) Oxygen index The oxygen index of the resin composition blended with magnesium hydroxide was measured in accordance with the test method of the combustion method based on JIS K 7201 plastic oxygen index. The test piece was an ISO multipurpose test piece, 10 to 15 test pieces were measured, and an average value was obtained. The seasoning was not particularly performed.

(2) Tensile test The tensile strength and elongation of the resin composition blended with magnesium hydroxide were measured in accordance with the JIS K 7113 plastic tensile test method. The test piece was a No. 1 dumbbell test piece, three test pieces were measured, and the average value was obtained. Seasoning was performed under conditions of an air temperature of 23 ° C. and a humidity of 50% for 48 hours or longer.

(3) Bending test Based on JIS K 7203 hard plastic bending test method, the bending strength and the bending elastic modulus of the resin composition test piece which mixed magnesium hydroxide were measured. The test piece was an ISO multipurpose test piece, three test pieces were measured, and an average value was obtained. The test speed was 2 mm / min. Seasoning was performed under conditions of an air temperature of 23 ° C. and a humidity of 50% for 48 hours or longer.

  The evaluation results are shown in Table 1.

  As shown in Table 1, in Example 1 and Example 2 according to the present invention, a high oxygen index is obtained as compared with Comparative Examples 1 to 3, and it is understood that the flame retardancy is excellent. It can also be seen that there is no particular problem in mechanical strength.

(Examples 3-7 and Comparative Examples 4-5)
As shown in Table 2, except that the mixing ratio (A) / (B) of magnesium hydroxide was changed, a compound was prepared in the same manner as in the above example, and molded using this compound. The oxygen index was measured. The results are shown in Table 2. Table 2 also shows the results of Examples 1-2 and Comparative Examples 1-2.

  As is clear from the results shown in Table 2, excellent flame retardancy can be obtained by setting the mixing ratio (A) / (B) of magnesium hydroxide within the range of 10/90 to 70/30. I understand.

(Examples 8-9 and Comparative Examples 6-7)
In Example 8, a compound was prepared in the same manner as in Example 2 except that magnesium hydroxide A2 was used as magnesium hydroxide (A), molded using this compound, and the oxygen index was measured.

  In Example 9, except that magnesium hydroxide B2 was used as magnesium hydroxide (B), a compound was prepared in the same manner as in Example 2 above, molded using this compound, and the oxygen index was measured. .

  In Comparative Example 6, a compound prepared by using magnesium hydroxide A2 and magnesium hydroxide A1 mixed at a weight ratio of 40/60 as a magnesium hydroxide flame retardant was prepared in the same manner as in the above Example. Molding was performed using this compound, and the oxygen index was measured.

  In Comparative Example 7, a compound was produced in the same manner as in the above Example, except that magnesium hydroxide B2 and magnesium hydroxide B1 were mixed at a weight ratio of 40/60, and molded using this compound. The oxygen index was measured.

  Table 3 shows the measurement results. Table 3 also shows the measured values of Example 2.

  Table 3 shows the BET specific surface area and average primary particle diameter of each magnesium hydroxide.

  As is clear from the results shown in Table 3, in Examples 2, 8 and 9 according to the present invention, a high oxygen index was obtained. Therefore, it can be seen that excellent flame retardancy can be obtained by following the present invention.

Claims (7)

(A) magnesium hydroxide having a BET specific surface area of less than 10 m ² / g and an average primary particle size of 0.5 μm or more;
(B) Magnesium hydroxide surface-treated with a lipophilic surface treatment agent, having a BET specific surface area of 10 m ² / g or more and 2.5 times or more of the BET specific surface area of magnesium hydroxide (A) Magnesium hydroxide having an average primary particle size of 0.4 μm or less,
A magnesium hydroxide flame retardant mixed at a weight ratio (magnesium hydroxide (A) / magnesium hydroxide (B)) of 10/90 to 70/30.   The magnesium hydroxide flame retardant according to claim 1, wherein the magnesium hydroxide (A) is surface-treated with a lipophilic surface treatment agent.   The lipophilic surface treatment agent is at least one selected from the group consisting of higher fatty acids, anionic surfactants, phosphate esters, esters of fatty acids and polyhydric alcohols, and coupling agents. The magnesium hydroxide flame retardant according to claim 1 or 2, characterized by the above.   The surface treatment agent is subjected to a surface treatment of 0.5 to 20 parts by weight with respect to 100 parts by weight of magnesium hydroxide in magnesium hydroxide (B) and / or magnesium hydroxide (A). The magnesium hydroxide flame retardant according to any one of -3.   Magnesium hydroxide (B) adds an alkali to a slurry containing a magnesium salt and a magnesium hydroxide seed crystal, thereby generating aggregated particles in which primary particles of magnesium hydroxide are aggregated. The magnesium hydroxide flame retardant according to any one of claims 1 to 4, wherein the magnesium hydroxide is obtained by wet-dispersing and then surface-treating with a surface treatment agent.   A flame retardant polymer composition comprising 1 to 200 parts by weight of the magnesium hydroxide flame retardant according to any one of claims 1 to 5 with respect to 100 parts by weight of a resin or rubber.   The flame retardant polymer composition according to claim 6, wherein a thermoplastic resin is used as the resin.