RU2574514C1 - Flame retardant, fireproof composition and moulded product - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: flame retardant includes particles of magnesium hydroxide, subjected to surface processing. Particles satisfy the following conditions from (A) to (D): (A) average particle diameter constitutes 2 mcm or less in accordance with laser diffraction method; (B) specific BET surface area constitutes from 3 to 15 m²/g; (C) degree of monodispersity equals 50% or more. Degree of monodispersity is represented by the following expression: Degree of monodispersity (%) = (average size of initial particles [mcm] in accordance with SEM method analysis/average size of particles [mcm] in accordance with laser diffraction method) × 100; and (D) immediately after drop-by-drop addition of 1 ml of 0.1 M nitric acid solution at rate of dropping 0.1 ml/minute to suspension, obtained by addition of 1.0 g of flame retardant to 100 ml of water mixed solution, containing 0.1 wt % of each, wetting substance and electrolyte, pH of suspension constitutes 9.0 or lower in accordance with potentiometric titration.

EFFECT: flame retardant possesses good dispersibility in organic polymer material and does not reduce properties of said material even after mixing with organic polymer material.

5 cl, 1 tbl, 7 ex

Description

FIELD OF THE INVENTION

The present invention relates to a flame retardant, a flame retardant composition and a molded product.

BACKGROUND

To date, halogen-containing flame retardants have been widely used, which were made mainly from organic halides (mainly bromide) to give fire resistance to molded products made from organic polymeric materials, such as plastic products or synthetic fibers. Halogen-containing flame retardants have an excellent flame retardant effect; however, gaseous halogen generated during decomposition during the molding process can lead to corrosion of the molding and processing equipment, or can adversely affect the physical properties of the molded product itself. Thus, flame retardants of the so-called non-halogen type of various types were developed as its alternative.

Magnesium hydroxide is a non-toxic inorganic substance, does not contain halogen and is environmentally friendly. Thus, this substance has been widely used as a typical non-halogen type flame retardant. Considering that magnesium hydroxide is an inorganic substance, a surfactant can be used with it to achieve, for example, improved dispersibility of the substance in organic polymeric materials (Patent Document 1), and the surface of the magnesium hydroxide particles is subjected to surface-active treatment. a substance, and then surface-treated particles can be used (Patent Document 2).

BACKGROUND OF THE PRIOR ART

PATENT DOCUMENT

Patent Document 1: JP-A-S60-110738.

Patent Document 2: JP-B-S60-57457.

SUMMARY OF THE INVENTION

PROBLEMS TO BE SOLVED BY THE INVENTION

However, with regard to conventional surface treated magnesium hydroxide flame retardants, the level or degree to which surface treatment is carried out (i.e., the level of surface treatment) is insufficient. Therefore, flame retardants may not have good workability when mixed with an organic polymer material, or the kneaded product to be obtained may not have good properties.

Thus, an object of the present invention is to provide a flame retardant that has good dispersibility in an organic polymer material and does not reduce the properties of this material even after mixing with an organic polymer material; flame retardant composition and molded product.

MEANS FOR SOLVING PROBLEMS

The author of the present invention has repeatedly carried out vigorous studies regarding the shape of magnesium hydroxide particles and the state of their treated surface, finding that the above problems can be solved by treating the surface of magnesium hydroxide particles having a predetermined particle shape. The present invention has been made on the basis of this finding.

The flame retardant of the present invention includes magnesium hydroxide particles subjected to surface treatment, and the particles satisfy the following conditions (A) to (D):

(A) the average particle size is 2 μm or less according to the laser diffraction method;

(B) the specific surface area according to BET is from 3 to 15 m ² / g;

(C) the degree of monodispersity is 50% or more, and the degree of monodispersity is represented by the following expression:

The degree of monodispersity (%) = (average primary particle size [μm] according to the SEM study / average particle size [μm] according to the laser diffraction method) × 100; and

(D) immediately after dropwise adding 1 ml of a 0.1 M nitric acid solution at a drop rate of 0.1 ml / minute to the suspension obtained by adding 1.0 g of flame retardant to 100 ml of an aqueous mixed solution containing 0.1% by weight, each wetting agent and electrolyte, the pH of the suspension is 9.0 or less according to potentiometric titration.

In a flame retardant, magnesium hydroxide simultaneously satisfies the specific requirements (A) - (D), thus, the surface treatment of magnesium hydroxide particles is carried out at the level of the primary particles. This makes it possible to obtain a flame retardant with excellent dispersibility in an organic polymer material and provides good properties even after mixing with an organic polymer material without reducing the properties of the material.

Regarding requirement (A), if the average particle size according to the laser diffraction method is more than 2 μm, the dispersibility of the flame retardant in the organic polymer material (and in the subsequently formed molded product) is reduced, so that the energy required for mixing can increase, or elongation when stretched, the resulting molded product may decrease. Regarding requirement (B), if the BET specific surface area is more than 15 m ² / g, the flame retardant is prone to aggregation when mixed with an organic polymer material. Thus, the dispersibility of the flame retardant in the organic polymer material (or in the molded product) is reduced, so that the elongation in tension of the molded product is reduced. Conversely, if the BET specific surface area is less than 3 m ² / g, fire resistance is reduced. Regarding requirement (C), if the degree of monodispersion of the magnesium hydroxide particles is less than 50%, the magnesium hydroxide particles are present not in the state of the primary particles, but in the aggregated state, so that the particles present in the vicinity of the respective centers of the aggregates are not sufficiently surface treated. In the case of an attempt to mix a flame retardant containing these aggregates with an organic polymer material, the aggregates are destroyed by the shear stress generated by kneading. Therefore, magnesium hydroxide particles that are not sufficiently surface treated are unprotected. At this time, magnesium hydroxide particles, which are not sufficiently subjected to surface treatment, come into contact with the organic polymer material, so that an unexpected reaction is initiated. Thus, the properties of the material resulting from the molded product are reduced (for example, elongation under tension). As for requirement (D), if the pH of the suspension is more than 9.0 after titration with nitric acid, the surface treatment of the particles of magnesium hydroxide becomes insufficient. In addition, in this case, the magnesium hydroxide particles come into contact with the organic polymer materials, so that an unexpected reaction is caused. Thus, the material properties of the resulting molded product are reduced (for example, elongation under tension). In the present description, with regard to the average primary particle size according to SEM measurements, the average particle size according to the laser diffraction method, specific BET surface area and potentiometric titration, the method for measuring each of these properties corresponds to the method described in the examples that will be described later.

In a flame retardant, it is preferable that the surface treatment be carried out using at least one substance selected from the group consisting of higher fatty acids, alkali metal salts of higher fatty acids, binders, esters derived from fatty acid and polyhydric alcohol, and phosphates derived from phosphoric acid and higher alcohol. This makes it possible to further improve the dispersibility of the magnesium hydroxide particles in the organic polymer material (and in the molded product).

In a flame retardant, it is preferred that the treatment is carried out by the wet method. When the surface treatment of the magnesium hydroxide particles is carried out by the wet method, it is possible to achieve surface treatment at the level of the primary particles, so that the dispersibility of the flame retardant can be increased and the decrease in the properties of the molded product can be more effectively prevented.

Another aspect of the present invention is a fire retardant composition comprising an organic polymer material and a flame retardant in an amount of from 5 to 500 parts by weight, based on 100 parts by weight of the organic polymer material. Since the flame retardant composition includes a flame retardant with good dispersibility and a well-treated surface, this composition may exhibit sufficient fire resistance. In addition, the reduction in the properties of the molded product obtained from the composition is limited, so that the molded product can be guaranteed to have the desired properties.

Another aspect of the present invention is a molded product obtained using a fire retardant composition.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an SEM photograph of a flame retardant from Example 1 of the present invention;

FIG. 2 is an SEM photograph of a flame retardant from Comparative Example 3 of the present invention; and

FIG. 3 is a graphical representation of titration curves showing the corresponding potentiometric titration results of flame retardants in the examples of the present invention.

MODES FOR CARRYING OUT THE INVENTION

An embodiment of the present invention will be described hereinafter. The flame retardant of this embodiment includes surface-treated magnesium hydroxide particles, the particles satisfying the following conditions (A) to (D): (A) the average particle size is 2 μm or less according to the laser diffraction method (hereinafter referred to as “average particle size according to laser diffraction method "may simply be referred to as" average particle size "); (B) the specific surface area according to BET is from 3 to 15 m ² / g; (C) the degree of monodispersity is 50% or more, and the degree of monodispersity is represented by the following expression: The degree of monodispersity (%) = (average primary particle size [μm] according to the SEM study / average particle size [μm] according to the laser diffraction method) × 100 (wording × average size of primary particles according to the SEM study "may simply be indicated as" average size of primary particles "); and (D) immediately after dropwise adding 1 ml of a 0.1 M nitric acid solution at a dripping rate of 0.1 ml / min to the suspension obtained by adding 1.0 g of flame retardant to 100 ml of an aqueous mixed solution containing 0.1% by the mass of each wetting agent and electrolyte, the pH of the suspension is 9.0 or less according to potentiometric titration. Since the flame retardant of the present invention contains surface-treated magnesium hydroxide particles satisfying conditions (A) to (D), the flame retardant has excellent dispersibility in the organic polymer material by surface treatment at the level of the primary particles. In addition, the flame retardant can give a molded product showing the desired properties.

(A) Average Particle Size According to Laser Diffraction Method

It is sufficient that the upper limit of the average particle size of magnesium hydroxide is equal to 2 μm. The upper limit is preferably 1.5 μm, more preferably 1.2 μm. Conversely, the lower limit of the average particle size is not particularly limited. The lower limit is preferably 0.1 μm, more preferably 0.3 μm from the point of view of preventing aggregation. When the average particle size of magnesium hydroxide falls within this range, the particles of magnesium hydroxide exhibit dispersibility sufficient to impart fire retardancy to the flame retardant, and their aggregation is further prevented, so that the surface treatment for each particle can be carried out at a sufficient level.

(B) BET specific surface area

The BET specific surface area of the magnesium hydroxide particles is not particularly limited provided that the surface area is in the range of 3 to 15 m ² / g. The BET specific surface area is in the range of preferably 4 to 10 m ² / g, more preferably 5 to 8 m ² / g. When the BET specific surface area falls within this range, the magnesium hydroxide particles can allow the flame retardant to provide fire resistance, and their aggregation can be further prevented in order to improve the dispersibility and level of surface treatment. As a result, a flame retardant composition and a molded article that have the desired properties can be obtained.

(C) The degree of monodispersity

The degree of monodispersion of magnesium hydroxide particles is an indicator representing the proportion of magnesium hydroxide particles remaining in the state of primary particles relative to all particles of magnesium hydroxide. When the degree of monodispersity is higher, a more substantial proportion of the particles of magnesium hydroxide is present in the form of primary particles. When the degree of monodispersity is lower, a larger proportion of the particles of magnesium hydroxide is present in the form of secondary particles into which the primary particles are aggregated. When measuring the degree of monodispersity, the following ratio is used: the ratio between the average size of the primary particles according to the SEM measurement and the average particle size according to the laser diffraction method. This is due to the fact that the SEM method is suitable for measuring the size of primary particles, and the laser diffraction method is suitable for measuring their average size (the average value of mixed particle sizes, consisting of the sizes of primary particles and the sizes of secondary particles).

The degree of monodispersity is not particularly limited, provided that the lower limit of this degree is 50%. The lower limit is preferably 55%, more preferably 60%. When the degree of monodispersity falls within this range, the magnesium hydroxide particles can be maintained in the state of the primary particles in order to prepare a flame retardant with good dispersibility and good surface finish. Although the upper limit of the degree of monodispersity is preferably 100%, the upper limit may be 90% or less due to physical limitations.

(D) pH after titration with nitric acid

The pH of the flame retardant suspension after titration with nitric acid is used as an indicator representing the state of the treated surface of the magnesium hydroxide particles in the suspension (see Japan Patent No. 4634671).

Specifically, magnesium hydroxide particles have alkaline properties; when the surface of the particles is not treated, an acid-base reaction proceeds between the particles of magnesium hydroxide and nitric acid, so that a high pH value is maintained; however, when the surface of the magnesium hydroxide particles is treated, the acid-base reaction is delayed or suppressed, so that the pH gradually decreases. Thus, by measuring the pH of the suspension after titration with nitric acid, it is possible to evaluate the level of surface treatment (or surface coating) of magnesium hydroxide particles.

In the present invention, magnesium hydroxide particles can be obtained in a state where the surface of the particles is treated at the level of the primary particles by adjusting the pH of the flame retardant suspension after titration with nitric acid to 9.0 or less. As a result, as well as when the flame retardant is mixed with the organic polymer material, the desired reaction between the flame retardant and the organic polymer material is suppressed, so that a reduction in the properties of the organic polymer material can be prevented. It is sufficient that the pH after titration with nitric acid is 9.0 or less. Preferably, the pH is 8.5 or less, more preferably 8.0 or less. As a lower limit, a pH close to 3.0 is preferred when all the dropwise added amount of nitric acid remains. However, the lower limit may be 3.5.

The method of obtaining particles of magnesium hydroxide

Magnesium hydroxide particles are typically prepared as follows: an aqueous solution of magnesium chloride or its hydrate is prepared and an alkali (such as an aqueous solution of sodium hydroxide) is added to form a suspension. After that, this suspension is subjected to hydrothermal treatment, obtaining a suspension. Then the suspension is filtered, washed and dried. In this way, the desired particles of magnesium hydroxide are obtained. When the surface treatment, which is the next step, is carried out by the wet method, it is preferable to filter and rinse the hydrothermally treated suspension, return the resulting filtrate to clean water to obtain a suspension of magnesium hydroxide, and then add surface treatment substance to this suspension. The hydrothermal treatment can be carried out at a temperature of from 100 to 250 ° C. with stirring in a known heating vessel for operation at elevated pressure, such as an autoclave, for about 1 to 10 hours.

Surface treatment

The magnesium hydroxide particles contained in the flame retardant of the present invention have a treated surface. The surface treatment agent may be a known compound used for the purpose of surface treatment. The surface treatment is preferably carried out using at least one substance selected from the group consisting of higher fatty acids, alkali metal salts of higher fatty acids, binders, esters derived from fatty acid and polyhydric alcohol, and phosphates derived from phosphoric acid and higher alcohol. This makes it possible to improve the dispersibility of the magnesium hydroxide particles in the organic polymer material (or the molded product) and to maintain or improve the properties of the flame retardant composition and the obtained molded product by improving the dispersibility. As a surface treatment agent, a surfactant is applicable.

(Higher fatty acids and alkali metal salts of higher fatty acids)

Examples of higher fatty acids include higher fatty acids that contain 10 or more carbon atoms, such as stearic acid, erucic acid, palmitic acid, lauric acid and behenic acid. Stearic acid is preferred in terms of dispersibility and ease of handling. Examples of alkali metal salts of higher fatty acids include alkali metal salts of the above higher fatty acids. The alkali metal is preferably lithium, sodium, potassium or the like. Alkali metal salts of higher fatty acids are preferred in terms of dispersibility. Of these salts, sodium stearate is more preferred. These acids or salts may be used individually or in any combination of two or more of these compounds.

(Binders)

Examples of binders include binders based on silanes, such as γ-glycidoxypropyltrimethoxysilane, β- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, γ-methacryloxypropyltrimethoxysilane, γ-metakriloksipropiltrietoksisilan, γ-akriloksipropilmetildimetoksisilan, vinyltriethoxysilane, vinyltriacetoxysilane, p-trimetoksisililstirol, p-trietoksisililstirol , p-trimethoxysilyl-α-methylstyrene, p-triethoxysilyl-α-methylstyrene, 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, N-2- (aminoethyl) -3-aminopropylmethyldimethoxy silane, N-2- (aminoethyl) -3-aminopropyltrimethoxysilane, N-2- (aminoethyl) -3-aminopropyltriethoxysilane, N-phenyl-3-aminopropyltrimethoxysilane, N-phenyl-3-aminopropyltriethoxysilane, N-propyl-3-aminopropyl 4-aminobutyltrimethoxysilane and decyltrimethoxysilane; titanate-based binders such as isopropyltriisostearoyl titanate, isopropyltris (dioctyl pyrophosphate) titanate, isopropyltri (N-aminoethyl aminoethyl) titanate and isopropyltridecylbenzene sulfonyl titanate; and aluminum-based binders, such as, for example, acetoalkoxyaluminium diisopropionate. These binders can be used individually or in any combination of two or more of these substances.

(Esters derived from fatty acid and polyhydric alcohol)

Examples of esters derived from fatty acid and polyhydric alcohol include esters derived from polyhydric alcohol, such as glycerol monostearate or glycerol monooleate, and fatty acids, and the like. Examples of phosphates include a monoester derived from phosphoric acid and oleyl alcohol, stearyl alcohol or the like, a diester derived from the same substances, or a mixture of these two esters. The monoester, diester or a mixture thereof may be phosphate in acid form or in the form of an alkali metal salt, amine salt or the like.

(Phosphates derived from phosphoric acid and higher alcohol)

Examples of phosphates derived from phosphoric acid and higher alcohol include a monoester derived from phosphoric acid and oleyl alcohol, stearyl alcohol or the like, a diester derived from the same substances, or a mixture of these two esters. The monoester, diester or this mixture may be phosphate in acid form or in the form of an alkali metal salt, amine salt or the like.

(Surface-active substance)

Preferred examples of the surfactant include anionic surfactants, cationic surfactants, amphoteric surfactants, and nonionic surfactants.

(Anionic surfactants)

Examples of anionic surfactants include alkyl sulfate salts, such as sodium lauryl sulfate, higher alcohol sodium sulfate, triethanolamine lauryl sulfate, alkyl benzene sulfate salts, such as sodium dodecyl benzene sulfate, such as sodium alkyl naphthalene sulfate, sodium sulfate disulphate, sodium sulfate disulphate alkyl diphenyl ether, such as sodium diphenyl ether disulfate, alkyl phosphate salts, such as potassium alkyl phosphate, salts with polyoxyethylene alkyl (or alkylallyl) sulfate such as polyoxyethylene lauryl ether sulfate sodium salt, polyoxyethylene alkyl ether sulfate sodium salt, polyoxyethylene alkyl ether triethanolamine salt and polyoxyethylene alkyl phenyl ether sulfate salt and the like.

(Cationic surfactants and amphoteric surfactants)

Examples of cationic surfactants and amphoteric surfactants include alkyl amine salts such as coconut oil amine acetate and stearylamine acetate; quaternary ammonium salts such as lauryl trimethyl ammonium chloride, stearyl trimethyl ammonium chloride, cetyl trimethyl ammonium chloride, distearyl dimethyl ammonium chloride and alkyl benzyl dimethyl ammonium chloride; alkyl betaines such as lauryl betaine, stearyl betaine and betaine lauryl carboxymethyl hydroxyethylimidazolium; amine oxides such as lauryl dimethyl amine oxide and the like.

(Non-ionic surfactants)

Examples of non-ionic surfactants include polyoxyethylene alkyl ethers such as polyoxyethylene lauryl ether, polyoxyethylene cetyl ether, polyoxyethylene stearyl ether, polyoxyethylene oleyl ether, and polyoxyethylene and higher alcohol ethers; polyoxyethylene alkylaryl ethers such as polyoxyethylene nonylphenyl ether; polyoxyethylene derivatives; esters of sorbitol and fatty acids such as sorbitan monolaurate, sorbitan monopalmitate, sorbitan monostearate, sorbitan tristearate, sorbitan monooleate, sorbitan trioleate, sorbitol sesquioleate and sorbitol distearate; polyoxyethylene sorbitan fatty acid esters, such as polyoxyethylene sorbitan monolaurate, polyoxyethylene sorbitan monolaurate, polyoxyethylene sorbitan monopalmitate, polyoxyethylene sorbitan monostearate, polyoxyethylene sorbitan triolearate, polyoxyethylene sorbitan polyoxyethylene sorbitan trioleate, such as esters; glycerol fatty acid esters such as glycerol monostearate, glycerol monooleate and self-emulsifying glycerol monostearate; polyoxyethylene fatty acid esters such as polyethylene glycol monolaurate, polyethylene glycol monostearate, polyethylene glycol distearate and polyethylene glycol monooleate; polyoxyethylene alkylamines; polyoxyethylene-cured castor oil, and alkyl alkanolamides.

(Surface treatment method)

In order to conduct surface treatment of the particles of magnesium hydroxide, use the wet method. You can adapt the surface treatment based on the known dry method, provided that you can achieve the desired level of surface treatment. In the wet method, it is sufficient to add a surface treatment substance in the form of a solution or emulsion to a suspension of magnesium hydroxide obtained by the above method for producing magnesium hydroxide particles, and then mechanically mix these components with each other at a temperature, for example, from 5 to 95 ° C. In the dry method, it is sufficient to add a surface treatment substance in the form of a liquid, emulsion or solid to the magnesium hydroxide powder with stirring using a mixing device, such as a Henkel mixer, and then sufficiently mix these components with each other with or without heating . The surface treatment is preferably carried out by the wet method in terms of the possibility of fixing the surface treatment substance to the surface of the magnesium hydroxide particles. The added amount of surface treatment agent can be selected accordingly. When the wet method is selected, this amount is in the range of preferably from 0.1 to 10% by weight, more preferably from 0.3 to 7% by weight, based on 100% by weight of magnesium hydroxide particles regarding sufficient surface treatment and preventing aggregation of the surface treatment agent. When the dry method is selected, the achieved state of surface treatment may be more heterogeneous than with the wet method. Thus, it is advisable to make the added amount of surface treatment substance large to a certain extent compared to the wet method. Specifically, this amount is in the range of preferably from 0.5 to 15% by weight, more preferably from 1 to 10% by weight, based on 100% by weight of magnesium hydroxide particles.

The surface-treated magnesium hydroxide particles are optionally subjected to a treatment suitably selected from washing with water, dehydration, granulation, drying, spraying, classification, and the like. Thus, you can cook the final product (flame retardant).

(Fire retardant composition)

The fire retardant composition of the present invention is obtained by introducing from 5 to 500 parts by weight of a flame retardant in 100 parts by weight of an organic polymer material. The amount of flame retardant administered is not specifically limited provided that the amount is within the range described above. The amount administered is preferably 20 to 400 parts by weight, based on 100 parts by weight of the organic polymer material. It is sufficient to make a choice regarding the amount administered, considering the fire resistance and properties of the flame retardant composition.

(Organic polymer material)

The organic polymeric material can be any organic polymeric material that is typically applicable to molded products. Examples thereof include thermoplastic resins, thermosetting resins, synthetic rubbers and other synthetic organic polymeric materials; natural rubbers and other natural organic polymeric materials; and similar.

(Thermoplastic resins)

Examples of thermoplastic resins include polyolefin-based polymers such as polyethylene, polypropylene, ethylene / propylene copolymer, polybutene and poly-4-methylpentene-1, and other polymers and copolymers of C2-C8 olefins (α-olefins); copolymer derived from olefin and diene, ethylene acrylate copolymer, polystyrene, ABS resin, AAC resin, copolymer of acrylic acid and styrene, copolymer of methyl methacrylate, butadiene and styrene, ethylene-vinyl chloride / vinyl acetate / vinyl acetate copolymer, copolymer , polyvinylidene chloride, polyvinyl chloride, chlorinated polyethylene, chlorinated polypropylene, copolymer of vinyl chloride with propylene, polyvinyl acetate, phenoxy resin, polyacetal, polyamide, polyimide, polycarbonate, polysulfone, polyphenylene oxide, polyphenylene sulfide, polyesters such as polyethylene terephthalate and polybutylene terephthalate, organosilicon resin, methacrylate resin and the like. Of these thermoplastic resins, polyolefin-based polymers or olefin-based copolymers are preferred since these polymers exhibit a high fire retardant effect with magnesium hydroxide particles and also have excellent mechanical strength.

(Thermosetting resin)

Examples of thermosetting resins include epoxies, phenolic resins, melamine resins, unsaturated polyester resins, alkyd resins, urea resins and the like.

(Synthetic rubbers)

Examples of synthetic rubbers include ethylene propylene diene rubber, butyl rubber, isoprene rubber, styrene butadiene rubber, nitrile butadiene rubber, chlorosulfonated polyethylene, isoprene acrylonitrile rubber, urethane rubber, acrylic rubber, rubber rubber, butadiene rubber.

(Flame retardant additive)

When a flame retardant is additionally mixed into the fire retardant composition of the present invention, the proportion of the magnesium hydroxide particles to be mixed can be reduced and the composition can be further improved in terms of the fire retardant effect. The flame retardant is preferably red phosphorus, coal powder, or a mixture thereof. Red phosphorus compounds may be conventional red phosphorus compounds for flame retardants or red phosphorus compounds whose surface is coated with, for example, a thermosetting resin, a polyolefin, a carboxylic acid polymer, titanium dioxide or titanium-aluminum condensate. The carbon powder compounds may be carbon black, activated carbon, or graphite. Carbon black can be prepared by any method selected from the oil furnace method, the gas furnace method, the channel method, the thermal method, or the acetylene method.

When a flame retardant is mixed in, its amount is in the range of preferably 0.5 to 20% by weight, more preferably 1 to 15% by weight of the total amount of the flame retardant composition.

(Other additives)

Additives other than the above components may be included in the flame retardant composition of the present invention, provided that the beneficial effects of the invention are not impaired. Examples of additives include an antioxidant, an antistatic agent, a pigment, a foaming agent, a plasticizer, a filler, a reinforcing filler, another flame retardant, a crosslinking agent, a light stabilizer, an ultraviolet absorber, a lubricant, and the like.

Molded product

A molded article of the present invention is prepared using a flame retardant composition. A molded product of the present invention can be obtained by mixing a predetermined number of particles of magnesium hydroxide into a synthetic resin and then molding the resulting composition by a known molding method. Examples of the molding method include extrusion followed by thermoforming, injection molding, calendering and the like.

Since the molded product of the present invention contains the above predefined particles of magnesium hydroxide, the molded product has excellent fire resistance and excellent appearance. The molded product is applicable for various applications that require fire resistance. Examples of applications include insulation of electrical wires, housings of household electrical appliances, wallpaper sheets for building materials, foamed insulation materials, mats, parts of connectors for electrical / electronic components, sealing materials for semiconductors, prepregs, multilayer printed circuit boards, laminated plates for printed circuit boards , highly functional synthetic fibers and the like.

EXAMPLES

Hereinafter, the present invention will be described in detail by way of examples; however, the invention is not limited to the examples described below, provided that the invention does not go beyond its essence.

Getting flame retardants

(Example 1)

High-purity MgCl ₂ · 6H ₂ O as the starting magnesium raw material was weighed to a mass of 480 g in a 3 L polyethylene vessel. To this amount was added 1 L of pure water, and this system was stirred to obtain an aqueous solution of MgCl ₂ . While stirring the solution, 510 ml of the alkaline feedstock, i.e. aqueous 8.3 n. NaOH solution (molar ratio (Mg ²⁺ / OH ^- = 1 / 1.8). Then pure water was additionally added to this mixture to obtain 2 L of suspension. This suspension was poured into a 3 L autoclave having a liquid-contacting region. from Hastelloy C-276 alloy. With stirring, the suspension was subjected to hydrothermal treatment at 140 ° C for 5 hours. After hydrothermal treatment, the suspension was subjected to vacuum filtration and then washed sufficiently with pure water, the volume of which was at least 20 times larger volume received Nogo resulting solid. The solid is then again returned to the pure water to prepare an emulsified slurry having a solid concentration of Mg (OH) _{2 of} 10 g / dl (0.1 g / ml). One liter of this suspension emulsified ( corresponding to the mass of solid Mg (OH) ₂ 100 g) was taken into a vessel made of 2 L SUS 316. With stirring, the suspension was heated to 80 ° C. Then, at 80 ° C, an aqueous solution of sodium stearate was added to it, the concentration of which was adjusted to 5% by mass, so that the amount, calculated on the mass of stearino oh acid was 0.6% by weight relative to the solid mass Mg (OH) _2. The suspension was heated at 80 ° C for 1 hour to wet the surface. Then this system was subjected to vacuum filtration, washed with water (a volume of at least 5 times the mass of solid Mg (OH) ₂ ), dried and ground to obtain a flame retardant powder.

(Example 2)

A flame retardant was obtained in the same manner as in example 1, except that instead of 510 ml of an aqueous 8.3 N NaOH solution, 630 ml of a suspension of Ca (OH) ₂ at a concentration of 25 g / dl (0.25 g / ml), and an aqueous solution of sodium stearate was added so that the amount, calculated on the weight of stearic acid, became 2.5% by weight relative to the solid mass of Mg (OH) ₂ .

(Example 3)

A flame retardant was obtained in the same manner as in Example 1, except that an aqueous solution of sodium stearate was added so that the amount, calculated on the weight of stearic acid, became 2.5% by weight relative to the solid mass of Mg (OH) ₂ .

(Comparison Example 1)

The flame retardant was obtained in the same manner as in example 1, except that no surface treatment was performed.

(Comparison Example 2)

A 20 L Henkel mixer was charged with 2 kg of flame retardant powder from Comparative Example 1, the surface treatment of which was not carried out, and 50 g of stearic acid powder. The admixed amount of stearic acid was 2.5% by weight of the weight of the flame retardant powder. In a Henkel mixer, the flame retardant powder was subjected to a dry surface treatment at 100 ° C and a rotation speed of 1900 rpm for 30 minutes to obtain a flame retardant powder. In the same manner as in example 1, with the exception of this feature, a flame retardant was obtained.

(Comparison Example 3)

To a 3 L vessel made of SUS 316, 270 g of MgO powder having a specific BET specific surface area of 10 m ² / g and 20 g of solid NaOH were added to 2.4 L of pure water. The system was heated to 80 ° C. with stirring, and a hydration reaction was carried out for 24 hours. After the hydration reaction, the suspension was subjected to vacuum filtration and then washed with a sufficient amount of pure water, the volume of which was at least 20 times the volume of the resulting solid. After that, the solid was returned to pure water again to prepare an emulsified suspension having a concentration of solid Mg (OH) ₂ of 10 g / dl (0.1 g / ml). This suspension was subjected to a wet surface treatment so that the amount, calculated on the weight of stearic acid, became 2.5% by weight relative to the mass of solid Mg (OH) ₂ . In the same manner as in example 1, with the exception of this feature, a flame retardant was obtained.

(Comparison Example 4)

High-purity MgCl ₂ · 6H ₂ O as the starting magnesium raw material was weighed to a mass of 480 g in a 15 L polyethylene vessel. To this amount was added 1 L of pure water, and this system was stirred to obtain an aqueous solution of MgCl ₂ . While stirring the solution, 510 ml of alkaline feedstock, i.e. aqueous 8.3 n. NaOH solution (molar ratio (Mg ²⁺ / OH ^- = 1 / 1.8), obtaining a suspension of Mg (OH) _2. This suspension of Mg (OH) _{2 was} used as seed crystals, and the above suspension was added to an aqueous solution of MgCl ₂ obtained by dissolving 480 g of high-purity MgCl ₂ · H ₂ O in 1 liter of pure water, then, while stirring this solution, 510 ml of an aqueous 8.3N NaOH solution was slowly added to it, then the solution was stirred for 5 minutes to hold the first reaction of the seed crystals. This reaction of the seed crystals, in General, was repeated 8 times. after the reaction of the seed crystals, which was carried out 8 times, was subjected to vacuum filtration and then sufficiently washed with pure water, the volume of which was at least 20 times the volume of the resulting solid, after which the solid was again returned to pure water to prepare an emulsified suspension having a concentration of solid Mg (OH) ₂ of 10 g / dl (0.1 g / ml). This emulsified suspension was subjected to a wet surface treatment so that the amount, calculated on the weight of stearic acid, became 2.5% by weight relative to the mass of solid Mg (OH) ₂ . In the same manner as in example 1, with the exception of this feature, a flame retardant was obtained.

Analysis and evaluation of flame retardants

For each of the flame retardants obtained in the examples and comparison examples, analyzes and evaluations were performed as described below. The results are shown in table 1, described below.

(1) Measurement of the average particle size

50 ml of ethanol was placed in a 100 ml volumetric flask and approximately 0.2 g of flame retardant powder was added to it. The system was sonicated for 3 minutes to obtain a liquid dispersion. A laser diffraction particle size distribution meter (Microtrac HRA, Model 9320-X100 manufactured by NIKKISO CO., LTD.) Was used to measure this prepared liquid dispersion, obtaining a D ₅₀ value by volume as the average particle size [μm].

(2) BET Specific Surface Area Measurement

The BET specific surface area meter (β sorb, model 4200 manufactured by NIKKISO CO., LTD.) Was used to measure the specific BET specific surface area flame retardant.

(3) Measurement of the degree of monodispersity

A scanning electron microscope (SEM) (S-23620 N, manufactured by Hitachi Ltd.) was used to obtain a photograph of a flame retardant powder particle image with a gain of 10,000. FIG. 1 is an SEM photograph of a flame retardant from Example 1, and FIG. 2 is an SEM photograph of a flame retardant from Comparative Example 3. Image analysis software was used to randomly select 50 primary particles of each individual flame retardant, and then the corresponding largest primary particle diameters were averaged. The degree of monodispersity was calculated in accordance with the following equation:

The degree of monodispersity (%) = (average value [μm] of the corresponding largest diameters of 50 primary particles, the diameters obtained by image analysis) / (average particle size [μm] obtained by laser diffraction) × 100

(4) Assessment of particle surface treatment by potentiometric titration

A volume of 100 ml was collected from an aqueous mixed solution containing 0.1% by weight of Triton X-100 as a wetting agent and 0.1% by weight of lithium perchlorate as an electrolyte. To this solution was added 1.0 g of flame retardant powder. A dispersion mixing device was used to subject the mixture to a dispersion treatment at 800 rpm for 10 minutes to prepare a suspension. When bubbling this suspension with nitrogen gas at 25 ° C, an automatic titrator (AT-400 manufactured by Kyoto Electronics Manufacturing Co., Ltd.) was used to drop an aqueous 0.1 M HNO ₃ solution into the suspension dropwise at a rate of 0, 1 ml / minute. A glass electrode was used to measure the pH of the titrated solution at 25 ° C. to obtain a titration curve. The titration curve of each of examples 1 and 3 and comparison examples 1-3 is shown in FIG. 3. The acid-base reaction regarding titration is as described below. The substance for surface treatment of Mg (OH) ₂ particles is reflected in the titration curve in that this substance inhibits this reaction.

Mg (OH) ₂ + 2HNO ₃ → Mg (NO ₃ ) ₂ + 2H ₂ O

(5) Melt kneading test

An EEA resin (ethylene / ethylene acrylate copolymer) (A-1150 manufactured by Japan Polyethylene Corporation) was used as the polyolefin resin. To 100 parts by weight by weight of an EEA resin, 100 parts by weight of a flame retardant powder was added, and the mixture was melt-kneaded at 150 ° C. in a Laboplast mill (manufactured by Toyo Seiki Kogyo Co., Ltd.) for 5 minutes.

During kneading, the constant moment of the kneading components was measured. When the kneading moment was 4.5 kgf · m (0.044 kN · m) or less as the target, the flame retardant was considered good. When the moment was more than 4.5 kgf · m (0.044 kN · m), the flame retardant was considered poor.

(6) tensile test

The mixed product produced in “(5) Melt Kneading Test” was pressed and molded at 150 ° C. to obtain a molded product in the form of a sheet having a thickness of 2 mm. From this molded product in the form of a sheet dumbbell-shaped samples were cut. The resulting test sample was used to conduct a tensile test in accordance with JIS K 7113. When the resulting tensile strength was 0.80 kgf / mm ² (7.84 MPa) or more as the target value, the flame retardant was considered good . When the tensile strength was less than 0.80 kgf / mm ² (7.84 MPa), the flame retardant was considered poor. When the resulting elongation in tension was 700% or more as the target value, the flame retardant was considered good. When the relative elongation in tension was less than 700%, the flame retardant was considered poor.

Table 1 Example 1 Example 2 Example 3 Comparison Example 1 Comparison Example 2 Comparison Example 3 Comparison Example 4 Magnesium Feed Connections Highly pure MgCl ₂ · 6H ₂ O salt Highly pure MgCl ₂ · 6H ₂ O salt Highly pure MgCl ₂ · 6H ₂ O salt Highly pure MgCl ₂ · 6H ₂ O salt Highly pure MgCl ₂ · 6H ₂ O salt Magnesium oxide Highly pure MgCl ₂ · 6H ₂ O salt Quantity used 480 g 480 g 480 g 480 g 480 g 270 g 480 g × 8 Alkaline feed Connections 8.3 n NaOH solution Suspension 25 g / dl (0.25 g / ml) Ca (OH) ₂ 8.3 n NaOH solution 8.3 n NaOH solution 8.3 n NaOH solution Solid NaOH 8.3 n NaOH solution Quantity used 510 ml 630 ml 510 ml 510 ml 510 ml 20 g 510 ml × 8 Reaction conditions - Autoclave Autoclave Autoclave Autoclave Autoclave Normal pressure Seed crystal depositing operation
(8 times) Reaction temperature ° C 140 115 140 140 140 80 25 Surface treatment The amount of stearic acid for processing - 0.6 2.5 2.5 0 0.6 2.5 2.5 Processing method - Wet method Wet method Wet method Wet method Dry method Wet method Wet method Particle properties The average size of the secondary particles (according to laser diffraction) μm 1,2 0.5 1,2 1,2 1,2 3,5 3.9 BET specific surface area m ² / g 5 13 5 5 5 7 42 The average size of primary particles (according to the SEM study) μm 0.8 0.3 0.8 0.8 0.8 0.3 0.05 The degree of monodispersity % 67 60 67 67 67 9 one pH after potentiometric titration - 7.9 7.7 7.5 10.0 9.1 9.6 9.9 EEA Resin Properties Kneading moment kgm 4.3 4.2 3.6 4.6 4.1 4.8 5,0 Rating - Good Good Good Bad Good Bad Bad Tensile strength kgf / mm ² 0.84 0.89 0.90 0.85 0.72 0.82 0.80 Rating - Good Good Good Good Bad Good Good Elongation in tension % 1100 1000 1240 350 990 1060 150 Rating - Good Good Good Bad Good Good Bad

As is clear from table 1, the flame retardant of each of the examples had good dispersibility in the polymer, and the resulting molded product had good properties. It is believed that the surface treatment level of the magnesium hydroxide particles constituting the flame retardant was sufficient to improve the dispersibility of the flame retardant in the polymer and, in addition, to sufficiently limit the reaction between the polymer and the flame retardant. However, in Comparative Example 1, the kneading moment increased and there was a low elongation under tension. It is believed that this was due to the fact that the pH value after titration with nitric acid was so high that the level of surface treatment decreased, although the form of the particles of magnesium hydroxide itself had no problems. In comparison example 2, tensile strength was found to be low. It is believed that this was due to the fact that the surface treatment was carried out by the dry method, so it was impossible to achieve a high level of surface treatment. In comparison example 3, the moment increased during kneading. Moreover, in comparison example 4, the moment during kneading increased, and there was a low elongation under tension. It is believed that the results of comparison examples 3 and 4 were caused by the fact that the aggregation of magnesium hydroxide particles occurred and thus the proportion of magnesium hydroxide particles present in the secondary particles was high, so that the level of surface treatment of the particles near the respective centers of the aggregates was low .

Claims (5)

1. Fire retardant, including particles of magnesium hydroxide, subjected to surface treatment, and the particles satisfy the following conditions (A) - (D):
(A) the average particle size is 2 μm or less according to the laser diffraction method;
(B) the specific surface area according to BET is from 3 to 15 m ² / g;
(C) the degree of monodispersity is 50% or more, and the degree of monodispersity is represented by the following expression:
The degree of monodispersity (%) = (average primary particle size [μm] according to the SEM study / average particle size [μm] according to the laser diffraction method) × 100; and
(D) immediately after dropwise adding 1 ml of a 0.1 M nitric acid solution at a drop rate of 0.1 ml / minute to the suspension obtained by adding 1.0 g of flame retardant to 100 ml of an aqueous mixed solution containing 0.1% by weight, each wetting agent and electrolyte, the pH of the suspension is 9.0 or less according to potentiometric titration. 2. Fire retardant according to claim 1, wherein the surface treatment is carried out using at least one substance selected from the group consisting of higher fatty acids, alkali metal salts of higher fatty acids, binders, esters derived from fatty acid and polyhydric alcohol , and phosphates derived from phosphoric acid and higher alcohol. 3. Fire retardant according to claim 1 or 2, where the surface treatment is carried out by the wet method. 4. Fire retardant composition comprising an organic polymer material and a flame retardant according to any one of paragraphs. 1-3 in an amount of 5 to 500 parts by weight, based on 100 parts by weight of an organic polymer material. 5. A molded product obtained using a flame retardant composition according to claim 4.

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