JP7745384B2 - Particles and their uses - Google Patents

Description

The present invention relates to particles and their uses.

In general, in order to impart heat resistance to a resin composition, a method of blending a flame-retardant compound such as an organic halogen compound or an organic phosphorus compound into the component is widely adopted.
However, the flame retardants described above corrode surrounding metal materials or emit a strong, irritating odor due to the decomposition gases generated by heating. Furthermore, the flame retardants plasticize the resin material, resulting in problems such as a deterioration in the mechanical and thermal properties of the component. Furthermore, to prevent the flame retardant from bleed-out onto the surface of the component over time, a large amount of flame retardant must be added.
In order to solve such problems in making resin compositions flame retardant, it has been considered to introduce a monomer consisting of a halogen compound or a phosphorus compound as a copolymer component and incorporate it into the resin composition when producing the resin composition. However, in order to impart sufficient flame retardancy to the resulting resin composition, it is necessary to add a large amount of the above-mentioned flame-retardant copolymer component to the resin composition, and as a result, the desirable properties that the component originally possesses may be lost.
In order to solve such problems, a method has been proposed in which particles containing a flame retardant are blended to make the member flame-retardant.

For example, Patent Documents 1 and 2 disclose microcapsules containing a flame retardant, which are prepared by dissolving a flame retardant in a monomer such as acrylonitrile or methyl methacrylate and then subjecting the resulting solution to suspension polymerization.
Furthermore, Patent Document 3 exemplifies microcapsules containing a flame retardant, which are produced by uniformly mixing a flame retardant with gelatin or an aqueous solution of gelatin and gum arabic, then adjusting the pH to acidic and cooling.
Furthermore, Patent Document 4 exemplifies a microencapsulated flame retardant in which a flame retardant is encapsulated by dissolving a polyvalent isocyanate in a flame retardant that is liquid at room temperature, dispersing the oil phase thus obtained in an aqueous phase as oil droplets, and then adding and dissolving a polyvalent amine in the aqueous phase of this emulsion, thereby causing a polyaddition reaction between the polyvalent isocyanate and the polyvalent amine at the interface between the aqueous phase and the oil phase, or by heating the emulsion, thereby causing a polyaddition reaction between the polyvalent isocyanate and water at the interface between the aqueous phase and the oil layer.
Furthermore, Patent Document 5 exemplifies microcapsules containing a flame retardant, which are produced by dispersing a finely powdered flame retardant in water and then adding dropwise a melamine-formaldehyde resin or a modified resin thereof while maintaining the pH at 3 to 7.

Japanese Unexamined Patent Publication No. 55-118988 Japanese Unexamined Patent Publication No. 55-122075 Japanese Unexamined Patent Publication No. 179241/1983 Japanese Patent Application Publication No. 7-26153 Japanese Unexamined Patent Publication No. 52-119653

However, it has been confirmed that the microcapsules exemplified in the above Patent Documents 1 to 5 do not have sufficient ability to retain the encapsulated flame retardant, and the encapsulated flame retardant bleeds out over time.
An object of the present invention is to provide particles that have excellent retention of the flame retardant contained therein and excellent stability over time.

After extensive research, the inventors discovered that particles containing an outer shell containing a polymer of a polymerizable component containing a specific monomer and a flame retardant encapsulated therein have high flame retardant retention, suppress bleed-out of the flame retardant over time, and have excellent stability over time, leading to the present invention.

That is, the present invention provides particles comprising an outer shell containing a polymer and a flame retardant encapsulated therein, wherein the polymer is a polymer of a polymerizable component containing the following monomer (A) and the following monomer (B), and the monomer (A) contains a carboxyl group-containing monomer (a1).
Monomer (A): Monomer having one polymerizable carbon-carbon double bond Monomer (B): Monomer having at least two polymerizable carbon-carbon double bonds

The particles of the present invention preferably satisfy at least one of the following requirements 1) to 3).
1) The weight ratio of the monomer (A) to the polymerizable component is 50 to 99.99% by weight, and the weight ratio of the monomer (B) to the polymerizable component is 0.01 to 50% by weight.
2) The monomer (A) further contains the following monomer (a2):
Monomer (a2): at least one selected from a nitrile-based monomer, a (meth)acrylic acid ester-based monomer, a monomer having a group reactive with a carboxyl group, and a styrene-based monomer; 3) the flame retardant includes at least one selected from an organic phosphorus compound, an organic halogen compound, and an inorganic compound.

The composition of the present invention comprises the above particles and a substrate component.
The molded article of the present invention is obtained by molding the above composition.

The particles of the present invention have a high flame retardant retention capacity, do not bleed out of the flame retardant over time, and are excellent in stability over time.
Since the composition of the present invention contains the above particles, there is no bleed-out of the flame retardant over time, and a molded article having excellent flame retardancy can be obtained.
The molded article of the present invention has excellent stability over time and excellent flame retardancy.

FIG. 1 is a schematic diagram illustrating an example of a particle.

The particles of the present invention comprise a polymer-containing outer shell and a flame retardant encapsulated within the shell, and are capable of imparting flame retardancy. Furthermore, the particles of the present invention themselves are flame retardant. The particles of the present invention are described in detail below.

〔particle〕
In order to further enhance the effect of suppressing bleed-out of the flame retardant, the particles of the present invention preferably have a structure having one or more independent pores inside, and are preferably particles containing a flame retardant in the pores inside. In particular, as shown in Figure 1, particles having a core-shell structure including a polymer-containing outer shell (shell) 1 and a flame retardant (core) 2 encapsulated therein are preferred, as they provide a high bleed-out suppression effect. Furthermore, it is preferred that the outer shell has a structure that is continuous with the polymer that forms it.

In the particles of the present invention, the polymer forming the outer shell is a polymer of polymerizable components containing the following monomer (A) and the following monomer (B), and the monomer (A) contains a carboxyl group-containing monomer (a1).
Monomer (A): Monomer having one polymerizable carbon-carbon double bond Monomer (B): Monomer having at least two polymerizable carbon-carbon double bonds

The polymer forming the outer shell is a polymer of polymerizable components containing monomer (A) and monomer (B), which essentially contain carboxyl group-containing monomer (a1). This adjusts the polarity of the outer shell, improving its density and mechanical strength, and suppressing the seepage of large amounts of flame retardant and the leakage of flame retardant due to particle crushing or dents, which is believed to result in excellent long-term stability.

The monomer (A) is a monomer having one (radically) polymerizable carbon-carbon double bond, and essentially contains a carboxyl group-containing monomer (a1).
The monomer (a1) is not particularly limited as long as it has one or more free carboxyl groups per molecule, and examples thereof include unsaturated monocarboxylic acids such as acrylic acid, methacrylic acid, ethacrylic acid, crotonic acid, and cinnamic acid; unsaturated dicarboxylic acids such as maleic acid, itaconic acid, and fumaric acid; anhydrides of unsaturated dicarboxylic acids; and unsaturated dicarboxylic acid monoesters such as monomethyl maleate, monoethyl maleate, monobutyl maleate, monomethyl fumarate, monoethyl fumarate, monomethyl itaconate, monoethyl itaconate, and monobutyl itaconate. The carboxyl groups of the monomer (a1) may be partially or entirely neutralized during or after polymerization. These monomers (a1) may be used alone or in combination of two or more.

The weight proportion of monomer (a1) in monomer (A) is not particularly limited, but is preferably 5% by weight or more. When this weight proportion is 5% by weight or more, the polarity of the outer shell can be efficiently adjusted, and strength tends to be further improved. In addition, the heat resistance and solvent resistance of the particles also tend to be improved. The upper limit of this weight proportion is preferably 100% by weight, more preferably 90% by weight, even more preferably 80% by weight, particularly preferably 75% by weight, and most preferably 70% by weight. On the other hand, the lower limit of this weight proportion is more preferably 10% by weight, even more preferably 15% by weight, particularly preferably 20% by weight, and most preferably 25% by weight.

It is preferable that the monomer (A) contains the following monomer (a2) in addition to the monomer (a1) in terms of achieving the effects of the present invention.
Monomer (a2): at least one selected from nitrile-based monomers, (meth)acrylic acid ester-based monomers, monomers having a group reactive with a carboxyl group, and styrene-based monomers

Examples of the nitrile monomer include acrylonitrile, methacrylonitrile, α-chloroacrylonitrile, α-ethoxyacrylonitrile, fumaronitrile, etc. These nitrile monomers may be used alone or in combination of two or more.
Examples of (meth)acrylic acid ester-based monomers include methyl (meth)acrylate, ethyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, t-butyl (meth)acrylate, propyl (meth)acrylate, n-octyl (meth)acrylate, dodecyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, stearyl (meth)acrylate, 2-chloroethyl (meth)acrylate, phenyl (meth)acrylate, isobornyl (meth)acrylate, cyclohexyl (meth)acrylate, and benzyl (meth)acrylate. In the present invention, the term "(meth)acrylate" refers to either acrylate or methacrylate. Furthermore, in the present invention, the (meth)acrylic acid ester-based monomer also refers to a compound that does not have a group reactive with a carboxyl group. These (meth)acrylic acid ester-based monomers may be used alone or in combination of two or more.

The monomer having a group reactive with a carboxyl group is not particularly limited, but examples thereof include monomers having a hydroxyl group, an amino group, an epoxy group, an isocyanate group, an aldehyde group, an azo group, a nitro group, a nitroso group, a thiol group, a sulfonic acid group, a phosphate group, etc.
Examples of monomers having a group reactive with a carboxyl group include (meth)acrylamide-based monomers such as N-methylol(meth)acrylamide, (meth)acrylamide, hydroxymethylacrylamide, hydroxyethylacrylamide, acetoneacrylamide, N-ethyl(meth)acrylamide, N-propyl(meth)acrylamide, N-hexyl(meth)acrylamide, N-cyclohexyl(meth)acrylamide, N-hydroxyethyl(meth)acrylamide, 2-acetamidoacrylic acid, N-phenyl(meth)acrylamide, N-nitrophenyl(meth)acrylamide, and diacetoneacrylamide; aldehyde-based monomers such as acrolein; and vinyl Examples of suitable monomers include sulfonic acid monomers such as sulfonic acid and N-t-butylacrylamidosulfonic acid; phosphoric acid monomers such as vinylphosphonic acid; N,N-dimethylaminoethyl (meth)acrylate; vinyl glycidyl ether; propenyl glycidyl ether; glycidyl (meth)acrylate; glycerin mono(meth)acrylate; 4-hydroxybutyl acrylate glycidyl ether; 2-hydroxyethyl (meth)acrylate; 2-hydroxypropyl (meth)acrylate; 2-hydroxybutyl (meth)acrylate; 4-hydroxybutyl (meth)acrylate; 2-hydroxy-3-phenoxypropyl (meth)acrylate; and p-hydroxystyrene. In the present invention, the term "(meth)acrylic" refers to either acrylic or methacrylic. These monomers having a group reactive with a carboxyl group may be used alone or in combination of two or more.

Examples of styrene-based monomers include styrene, α-methylstyrene, vinyltoluene, t-butylstyrene, p-nitrostyrene, and chloromethylstyrene. These styrene-based monomers may be used alone or in combination of two or more.

When monomer (A) further contains monomer (a2), the weight percentage of monomer (a2) in monomer (A) is not particularly limited, but is preferably 5 to 95% by weight. A weight percentage of 5% by weight or more tends to provide sufficient flexibility and prevent the outer shell from breaking during processing, while a weight percentage of 95% by weight or less tends to provide sufficient heat resistance and solvent resistance. The upper limit of this weight percentage is more preferably 90% by weight, even more preferably 85% by weight, particularly preferably 80% by weight, and most preferably 75% by weight. The lower limit of this weight percentage is more preferably 10% by weight, even more preferably 15% by weight, and particularly preferably 20% by weight.

The monomer (A) may contain, in addition to the monomer (a1), a monomer other than the monomer (a2).
Examples of the monomer other than the monomer (a2) include vinyl ester-based monomers such as vinyl acetate, vinyl propionate, and vinyl butyrate; halogenated vinyl-based monomers such as vinylidene chloride, vinyl chloride, vinyl bromide, and vinyl fluoride; maleimide-based monomers such as N-phenylmaleimide and N-cyclohexylmaleimide; unsaturated monoolefin-based monomers such as ethylene, propylene, butylene, and isobutylene; vinyl ether-based monomers such as vinyl methyl ether, vinyl ethyl ether, vinyl propyl ether, vinyl isopropyl ether, vinyl butyl ether, vinyl isobutyl ether, vinyl-2-ethylhexyl ether, vinyl cyclohexyl ether, and vinyl-4-hydroxybutyl ether; vinyl ketone-based monomers such as vinyl methyl ketone, vinyl hexyl ketone, and methyl isopropenyl ketone; N-vinyl-based monomers such as N-vinylpyrrole, N-vinylcarbazole, N-vinylindole, and N-vinylpyrrolidone; and vinyl naphthalene salts.

The weight percentage of monomer (A) in the polymerizable component is not particularly limited, but is preferably 50 to 99.99% by weight. A weight percentage of 50% by weight or higher tends to improve the strength of the outer shell, while a weight percentage of 99.99% by weight or lower tends to improve the density of the outer shell. The upper limit of this weight percentage is more preferably 99.9% by weight, even more preferably 99.7% by weight, particularly preferably 99.5% by weight, and most preferably 99% by weight. The lower limit of the weight percentage of monomer (A) is more preferably (1) 60% by weight, (2) 70% by weight, (3) 80% by weight, (4) 85% by weight, (5) 90% by weight, or (6) 93% by weight (the larger the number in parentheses, the more preferable it is).

It is preferable from the viewpoint of solvent resistance that the monomer (A) contains a nitrile monomer in addition to the monomer (a1).
When the monomer (A) contains a nitrile monomer, the weight ratio of the nitrile monomer to the total weight of the monomer (a1) and the nitrile monomer is preferably 5 to 95% by weight. The upper limit of this weight ratio is more preferably 90% by weight, even more preferably 85% by weight, particularly preferably 80% by weight, and most preferably 75% by weight. On the other hand, the lower limit of this weight ratio is more preferably 10% by weight, even more preferably 15% by weight, particularly preferably 20% by weight, and most preferably 25% by weight.

Monomer (B) is a monomer having at least two (radically) polymerizable carbon-carbon double bonds, and introduces a cross-linked structure into the resulting polymer, which improves the density of the outer shell and prevents leakage of the encapsulated flame retardant.
Examples of the monomer (B) include ethylene glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate, propylene glycol di(meth)acrylate, 1,3-butylene glycol di(meth)acrylate, 1,4-butanediol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, 1,9-nonanediol di(meth)acrylate, 1,10-decanediol di(meth)acrylate, trimethylolpropane di(meth)acrylate, PEG#200 di(meth)acrylate, PEG#400 di(meth)acrylate, PEG#600 di(meth)acrylate, PEG#1000 di(meth)acrylate, dipropylene glycol ... Examples of the monomer (B) include di(meth)acrylates such as propylene glycol di(meth)acrylate, polypropylene glycol #400 di(meth)acrylate, polypropylene glycol #700 di(meth)acrylate, polytetramethylene glycol di(meth)acrylate, polytetramethylene glycol #650 di(meth)acrylate, ethoxylated polypropylene glycol #700 di(meth)acrylate, neopentyl glycol di(meth)acrylate, and tri(meth)acrylates such as trimethylolpropane tri(meth)acrylate and pentaerythritol tri(meth)acrylate; aromatic divinyl compounds such as divinylbenzene and divinylnaphthalene; allyl methacrylate; triacrylformal; triallyl isocyanate; butadiene, etc. These monomers (B) may be used alone or in combination of two or more. In the present invention, a series of compounds expressed as "PEG#xxx di(meth)acrylate" means polyethylene glycol di(meth)acrylate, and the average molecular weight of the polyethylene glycol portion is xxx.

The weight percentage of monomer (B) in the polymerizable component is not particularly limited, but is preferably 0.01 to 50% by weight. A weight percentage of 0.01% by weight or higher tends to improve the density of the outer shell, while a weight percentage of 50% by weight or lower tends to improve the strength of the outer shell. The upper weight percentage of monomer (B) is more preferably (1) 40% by weight, (2) 30% by weight, (3) 20% by weight, (4) 15% by weight, (5) 10% by weight, or (6) 7% by weight (the larger the number in parentheses, the more preferable it is). The lower weight percentage of monomer (B) is more preferably 0.1% by weight, even more preferably 0.3% by weight, particularly preferably 0.5% by weight, and most preferably 1% by weight.

The weight ratio (a1/B) of monomer (a1) to monomer (B) contained in the polymerizable component is not particularly limited, but is preferably 0.1 to 500. When this weight ratio is 0.1 or more, the polarity of the polymer forming the outer shell tends to be improved, and when this weight ratio is 500 or less, the strength of the particles tends to be improved. The upper limit of this weight ratio is more preferably 350, even more preferably 250, particularly preferably 200, and most preferably 150. On the other hand, the lower limit of this weight ratio is more preferably 0.5, even more preferably 1, particularly preferably 2, and most preferably 5.

In the particles of the present invention, the encapsulated flame retardant is a component that can impart flame retardancy when released from the particles.
Examples of flame retardants include organic phosphorus compounds such as phosphate ester compounds such as bisphenol A bis(diphenyl phosphate), triphenyl phosphate, tricresyl phosphate, trixylenyl phosphate, cresylphenyl phosphate, trimethyl phosphate, triethyl phosphate, and tris(β-chloropropyl)phosphate, and phosphazene compounds such as aryloxycyclophosphazene; organic halogen compounds such as tetrabromobisphenol A (TBBA), decabromodiphenyl ether (deca-BDE), tribromophenol, hexabromocyclododecane (HBCD), ethylene bis(tetrabromophthalimide), brominated polyethylene, and chlorinated paraffin; melamine cyanurate; silicone; and inorganic compounds such as antimony trioxide, magnesium hydroxide, aluminum hydroxide, red phosphorus, and ammonium polyphosphate. These flame retardants may be used alone or in combination of two or more.

The flame retardant is not particularly limited, but preferably contains at least one selected from organic phosphorus compounds, organic halogen compounds, and inorganic compounds, since this can efficiently impart flame retardancy.
The flame retardant may be in a liquid or solid state, and is preferably in a liquid state, since it can be efficiently encapsulated and released from the particles more efficiently.

The weight ratio of the flame retardant to the entire particle (hereinafter sometimes simply referred to as the flame retardant encapsulation rate) is not particularly limited, but is preferably 5 to 80% by weight. A flame retardant encapsulation rate of 5% by weight or more tends to provide sufficient flame retardancy. On the other hand, a flame retardant encapsulation rate of 80% by weight or less tends to suppress leakage of the flame retardant. The upper limits of the encapsulation rate are preferably (1) 75% by weight, (2) 70% by weight, (3) 65% by weight, (4) 60% by weight, (5) 55% by weight, and (6) 50% by weight (the larger the number in parentheses, the more preferable). On the other hand, the lower limits of the encapsulation rate are preferably (1) 10% by weight, (2) 13% by weight, (3) 15% by weight, (4) 18% by weight, and (5) 20% by weight (the larger the number in parentheses, the more preferable). The weight ratio of the flame retardant in the particles of the present invention is measured using the method described in the Examples.

The average particle size of the particles of the present invention is not particularly limited, but is preferably 0.1 to 300 μm. When the average particle size is 0.1 μm or more, the outer shell has sufficient thickness, which tends to improve the encapsulation and retention of the flame retardant. On the other hand, when the average particle size is 300 μm or less, leakage of the flame retardant due to particle crushing or dents tends to be suppressed. The upper limit of the average particle size is preferably (1) 200 μm, (2) 150 μm, (3) 120 μm, (4) 100 μm, (5) 75 μm, (6) 60 μm, (7) 50 μm, and (8) 45 μm (the larger the number in parentheses, the more preferable it is). On the other hand, the lower limit of the average particle size is preferably (1) 0.5 μm, (2) 1 μm, (3) 3 μm, (4) 5 μm, and (5) 10 μm (the larger the number in parentheses, the more preferable it is). The average particle size of the particles of the present invention is measured using the method described in the Examples.

The ratio (d1/d2) of the inner diameter (d1) to the outer diameter (d2) of the particles of the present invention is not particularly limited, but is preferably 0.20 to 0.95. A ratio of 0.2 or greater tends to provide sufficient flame retardancy, while a ratio of 0.95 or less tends to improve particle strength. The upper limit of this ratio is more preferably 0.93, even more preferably 0.90, particularly preferably 0.87, and most preferably 0.85. Meanwhile, the lower limit of this ratio is more preferably 0.25, even more preferably 0.30, particularly preferably 0.35, and most preferably 0.40. The ratio (d1/d2) of the inner diameter (d1) to the outer diameter (d2) of the particles of the present invention is measured using the method described in the Examples.

The true specific gravity of the particles of the present invention is not particularly limited, but is preferably 0.70 to 2.5. Having the true specific gravity within the above range is preferable because it more effectively suppresses bleed-out of the flame retardant. The upper limit of the true specific gravity is more preferably 2.0, even more preferably 1.8, and particularly preferably 1.5. On the other hand, the lower limit of the true specific gravity is more preferably 0.80, even more preferably 0.90, and particularly preferably 1.0. The true specific gravity of the particles of the present invention is measured using the method described in the Examples.

[Method for producing particles]
The method for producing the particles of the present invention is not particularly limited, but is preferably a method including a step of dispersing a polymerizable component containing a monomer (A) having one polymerizable carbon-carbon double bond and a carboxyl group-containing monomer (a1), a monomer (B) having at least two polymerizable carbon-carbon double bonds, and a flame retardant in an aqueous dispersion medium, and polymerizing the polymerizable component (polymerization step). The polymerization step is a step of dispersing an oily mixture containing the polymerizable component and the flame retardant in an aqueous dispersion medium, and polymerizing the polymerizable component.

(Polymerization process)
In the polymerization step, the polymerizable components are preferably polymerized in the presence of a polymerization initiator, which is preferably contained in the oily mixture.
Examples of the polymerization initiator include peroxides such as peroxydicarbonate, peroxyester, and diacyl peroxide; azo compounds such as azonitrile, azoester, azoamide, azoalkyl, and polymeric azo initiator; and redox initiators. These polymerization initiators may be used alone or in combination of two or more. The polymerization initiator is preferably an oil-soluble polymerization initiator that is soluble in the polymerizable component.
The amount of the polymerization initiator used is not particularly limited, but is preferably 0.05 to 10 parts by weight, more preferably 0.1 to 8 parts by weight, and even more preferably 0.2 to 5 parts by weight, per 100 parts by weight of the polymerizable component.

The aqueous dispersion medium is prepared, for example, by blending water (ion-exchanged water) with a dispersion stabilizer, a dispersion stabilization aid, a polymerization aid, an electrolyte, etc., as required.
In the method for producing the particles of the present invention, it is preferable to add a dispersion stabilizer to stabilize the droplets and control the particle size. The dispersion stabilizer is not particularly limited, but is preferably an organic dispersion stabilizer and/or an inorganic dispersion stabilizer.
Examples of organic dispersion stabilizers include particulate stabilizers, water-soluble polymers, nanocellulose, etc. Examples of particulate stabilizers include those used in Pickering emulsions. Examples of water-soluble polymers include polyvinyl alcohol, methyl cellulose, hydroxyethyl methyl cellulose, hydroxypropyl methyl cellulose, polyacrylic acid, etc.
Examples of inorganic dispersion stabilizers include clay minerals, tricalcium phosphate, magnesium pyrophosphate obtained by a metathesis method, calcium pyrophosphate, colloidal silica, alumina sol, magnesium hydroxide, and other inorganic compounds.
These dispersion stabilizers may be used alone or in combination of two or more. The amount of the dispersion stabilizer used is preferably 0.05 to 100 parts by weight, more preferably 0.2 to 70 parts by weight, per 100 parts by weight of the oily mixture.

A dispersion stabilization aid may also be used in combination to stabilize the droplets and control particle size. Examples of dispersion stabilization aids include polymer-type dispersion stabilization aids, and surfactants such as cationic surfactants, anionic surfactants, zwitterionic surfactants, and nonionic surfactants. These dispersion stabilization aids may be used alone or in combination of two or more.

The aqueous dispersion medium may contain an electrolyte. Examples of the electrolyte include sodium chloride, magnesium chloride, calcium chloride, sodium sulfate, magnesium sulfate, ammonium sulfate, sodium carbonate, etc. These electrolytes may be used alone or in combination of two or more.
The content of the electrolyte is not particularly limited, but is preferably 0.1 to 50 parts by weight per 100 parts by weight of the aqueous dispersion medium.

The aqueous dispersion medium may contain a polymerization aid, which can suppress particle aggregation and scale generation in a polymerization reactor (specifically, aggregation due to strong adhesion of polymers to the outer shell surfaces of particles during polymerization of the polymerizable component, and adhesion of polymers to the inner walls of the polymerization reactor).
Examples of the polymerization aid include nitrite, sodium sulfite, copper chloride, iron chloride, dichromate, stannic chloride, hydroquinone, ethylenediaminetetraacetate, water-soluble ascorbic acids, water-soluble polyphenols, water-soluble B vitamins, etc. These polymerization aids may be used alone or in combination of two or more.

In the polymerization step, the oily mixture is dispersed in an aqueous dispersion medium so as to prepare spherical oil droplets having a predetermined particle size. Examples of methods for dispersing the oily mixture include a method of stirring with a homomixer (e.g., manufactured by Primix Corporation), a method using a static dispersing device such as a static mixer (e.g., manufactured by Noritake Engineering Co., Ltd.), a membrane suspension method, an ultrasonic dispersion method, and other common dispersion methods.
Next, the dispersion in which the oily mixture is dispersed as spherical oil droplets in the aqueous dispersion medium is heated to carry out polymerization. During the polymerization reaction, it is preferable to stir the dispersion, and the stirring may be carried out gently to a degree that prevents the oily mixture and the particles after polymerization from floating up or settling down.

The polymerization temperature can be freely set depending on the type of polymerization initiator, but is preferably controlled within the range of 30 to 100°C, and more preferably 40 to 90°C. The reaction temperature is preferably maintained for approximately 1 to 20 hours. There are no particular restrictions on the initial polymerization pressure, but it is preferably in the range of 0 to 5 MPa, and more preferably 0.02 to 3 MPa, in gauge pressure.

The particles of the present invention may be in the form of a slurry, a wet powder, or a dry powder. When the particles of the present invention are in the form of a wet powder, they can be obtained, for example, by dehydrating the slurry containing the particles obtained by the above-mentioned production method using a centrifuge, a pressure press, a vacuum dehydrator, or the like. The moisture content of such a wet powder is not particularly limited, but is usually 10 to 50% by weight, preferably 15 to 45% by weight, and more preferably 20 to 40% by weight.
The wet powder obtained above can be dried to a dry powder using a tray dryer, an indirect heating dryer, a fluidized bed dryer, a vacuum dryer, a vibration dryer, a flash dryer, etc. Alternatively, the slurry can be dried using a spray dryer, a fluidized bed dryer, etc. to obtain a dried powder.

In addition to the methods described above, other methods for producing the particles of the present invention include interfacial polymerization, reverse phase emulsification, and emulsion polymerization. It is also possible to produce the particles using methods that do not produce droplets in an aqueous dispersion medium, such as submerged drying, coacervation, spray drying, and dry mixing.

[Composition and Molded Article]
The composition of the present invention contains the particles described above and a base component, and can provide a molded article having excellent flame retardancy.
Examples of the base material component include rubbers such as natural rubber, isoprene rubber (IR), butadiene rubber (BR), styrene-butadiene rubber (SBR), chloroprene rubber (CR), nitrile rubber (NBR), butyl rubber, silicone rubber, acrylic rubber, urethane rubber, fluororubber, polyether rubber, ethylene-propylene rubber (EPM), and ethylene-propylene-diene rubber (EPDM); thermosetting resins such as epoxy resin, phenolic resin, unsaturated polyester resin, polyurethane, polyimide, and polyamideimide; waxes such as polyethylene wax and paraffin wax; polyolefin resins such as ethylene-vinyl acetate copolymer (EVA), polyethylene (PE), modified polyethylene, polypropylene (PP), modified polypropylene, and modified polyolefin; polyvinyl chloride (PVC); acrylic resin; thermoplastic polyurethane; acrylonitrile-styrene copolymer (AS resin), acrylonitrile-butadiene-styrene copolymer (ABS resin); Examples of suitable base materials include polyethylene (PS), (meth)acrylate-styrene copolymers, polyamide resins (such as nylon 6 and nylon 66), modified polyamides, engineering plastics such as polycarbonate, polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polyacetal (POM), polyphenylene sulfide (PPS), polyphenylene ether (PPE), modified polyphenylene ether, polyether ether ketone, polyether sulfone, and polyphthalamide, thermoplastic resins such as fluororesins, ionomer resins such as ethylene-based ionomers, urethane-based ionomers, styrene-based ionomers, and fluorine-based ionomers, thermoplastic elastomers such as olefin-based elastomers, styrene-based elastomers, urethane-based elastomers, polyester-based elastomers, polyamide-based elastomers, and fluorine-based elastomers, bioplastics such as polylactic acid (PLA), cellulose acetate, PBS, PHA, and starch resins, and liquid crystal polymers. These base materials may be used alone or in combination.
Furthermore, in addition to the particles and base component described above, the composition of the present invention may contain additives such as antioxidants, ultraviolet absorbers, stabilizers, fillers, plasticizers, pigments, and antistatic agents, as well as solvents, lubricants, organic powders other than the particles of the present invention, inorganic powders, and the like, depending on the intended use.

The amount of particles contained in the composition of the present invention is not particularly limited, but is preferably 0.1 to 600 parts by weight per 100 parts by weight of the base component. The upper limit of the content is more preferably 400 parts by weight, even more preferably 200 parts by weight, and especially preferably 100 parts by weight. On the other hand, the lower limit of the content is more preferably 0.3 parts by weight, even more preferably 0.5 parts by weight, especially preferably 1 part by weight, and most preferably 3 parts by weight. When the content is within the above range, a molded article with sufficient flame retardancy tends to be obtained.

The composition of the present invention can be obtained by mixing the particles and base component described above, and various additives as necessary. Alternatively, a composition containing the particles and base component described above can be prepared and then further mixed with the base component to form a composition. Alternatively, a composition containing particles and a base component with a relatively low melting point can be prepared and then further mixed with the base component to form a composition, which is preferable because it can achieve good particle dispersibility. There are no particular limitations on the relatively low melting point, but it is preferably 50 to 200°C, more preferably 50 to 170°C, even more preferably 50 to 140°C, particularly preferably 50 to 110°C, and most preferably 50 to 80°C.

The composition of the present invention may be in the form of a liquid or a paste. When the composition of the present invention is in the form of a liquid or a paste, it can be used as a coating composition, an adhesive composition, a pressure-sensitive adhesive composition, an electrically insulating varnish composition, etc.

Mixing can be carried out using, for example, a mixer, mixer, Henschel mixer, super mixer, ribbon mixer, ribbon blender, kneader, roll, mixing roll, single-screw kneader, twin-screw kneader, multi-screw kneader, etc.

The molded article of the present invention is obtained by molding the composition described above.
As the molding method, depending on whether the resin is a thermoplastic resin or a thermosetting resin, a commonly used molding method such as extrusion molding, injection molding, vacuum molding, blow molding, compression molding, transfer molding, RIM molding, or cast molding can be appropriately adopted.
The amount of the above-described particles contained in the molded article of the present invention is not particularly limited, but is preferably 0.1 to 100 parts by weight per 100 parts by weight of the base component. The upper limit of the content is more preferably 80 parts by weight, even more preferably 50 parts by weight, and particularly preferably 40 parts by weight. On the other hand, the lower limit of the content is more preferably 0.3 parts by weight, even more preferably 0.5 parts by weight, particularly preferably 1 part by weight, and most preferably 3 parts by weight.

The molded article of the present invention has excellent flame retardancy and can therefore be widely used industrially as a variety of textile products such as woven fabrics, knitted fabrics, carpeting, and nonwoven fabrics, as well as a variety of components in the automotive, building, office automation, home appliance, and electronic equipment fields. In particular, it can be suitably used as a vehicle sealant or a building sealant.

Examples of the particles of the present invention are described below in detail. However, the present invention is not limited to these examples. The methods for measuring physical properties, evaluation items, and evaluation methods in the examples and comparative examples are as follows. Furthermore, in the following examples and comparative examples, "%" means "% by weight" and "parts" means "parts by weight" unless otherwise specified.

[Average particle size of particles]
A Microtrac particle size distribution analyzer (model 9320-HRA, manufactured by Nikkiso Co., Ltd.) was used, and the D50 value determined by volume-based measurement was taken as the average particle size of the particles.

[Measurement of true specific gravity (D1) of particles]
The true specific gravity (D1) of the particles at 25° C. was measured by an immersion pycnometer method using isopropyl alcohol.

[Measurement of the encapsulation rate of flame retardant]
1.0 g of particles was placed in a stainless steel evaporating dish with a diameter of 80 mm and a depth of 15 mm, and its weight was measured (W ₁ (g)). 30 mL of N,N-dimethylformamide was added to uniformly disperse the particles, and the mixture was left at room temperature for 24 hours, after which it was dried under reduced pressure at 130°C for 2 hours. After drying under reduced pressure, the sample was washed three times with 30 mL of isopropyl alcohol, dried at 100°C for 10 minutes, and its weight was measured (W ₂ (g)).
The moisture content of the particles was measured using a Karl Fischer moisture meter (Model MKA-510N, manufactured by Kyoto Electronics Manufacturing Co., Ltd.) and was taken as C _w1 (wt %).
From the above W ₁ , W ₂ and C _w1 , the inclusion rate (C (wt %)) of the inclusions in the particles was calculated by the following formula.
C=100×[(W ₁ - _{W 2} )-C _W1 /100]/(1.0-C _W1 /100)

[Measurement of true specific gravity of polymer forming particle outer shell]
10 g of the particles were dispersed in 200 mL of N,N-dimethylformamide, treated with an ultrasonic disperser for 30 minutes, immersed at room temperature for 24 hours, filtered, and dried under vacuum at 120°C for 5 hours to isolate the polymer forming the particle shell (hereinafter, sometimes simply referred to as the shell polymer). The true specific gravity (D2) of the obtained shell polymer was measured in the same manner as in the measurement of the true specific gravity of the particles described above.

[Calculation of particle shell thickness]
The thickness <t> of the outer shell of the particle was calculated using the following formula.
<t>=<x>/2 [1-{1-D1×(1-C/100)/D2} ^1/3 ]
<x>: average particle size (μm)
D1: True specific gravity of particle D2: True specific gravity of polymer forming outer shell C: Encapsulation rate of flame retardant (wt%)

[Calculation of the ratio (d1/d2) of the inner diameter (d1) to the outer diameter (d2) of a particle]
The ratio (d1/d2) of the inner diameter (d1) to the outer diameter (d2) of the particle was calculated using the following formula.
d1=<x>-2<t>
d2=<x>
d1/d2=(<x>-2<t>)/<x>=1-2<t>/<x>

<Particle stability over time>
The particles were allowed to stand for 60 days at 40° C. After standing, 10 g of the particles were washed three times with 30 mL of isopropyl alcohol, dried at 100° C. for 1 hour, and then their weight was measured (W ₃ (g)).
Furthermore, the moisture content of the particles after standing was measured using a Karl Fischer moisture meter (Model MKA-510N, manufactured by Kyoto Electronics Manufacturing Co., Ltd.) and was taken as C _w2 (wt %).
From the above _W3 and _Cw2 , the flame retardant retention rate R1 (%) of the particles after standing was calculated using the following formula. When R1 was 90% or more, the particles were evaluated as having excellent stability over time, with the flame retardant bleed-out being suppressed. On the other hand, when R1 was less than 90%, the flame retardant bleed-out occurred, with the particles being evaluated as having poor stability over time.
R1=10×(W ₃ +C _w2 /100)

<Thermal stability of particles>
10 g of particles were placed in a stainless steel evaporating dish with a diameter of 80 mm and a depth of 15 mm, heated at 200°C for 1 hour, and their weight was measured ( _W4 (g)). After heating, the particles were washed three times with 30 mL of isopropyl alcohol, dried at 100°C for 10 minutes, and their weight was measured ( _W5 (g)).
From the above _W4 and _W5 , the retention rate R2 (%) of the encapsulated flame retardant in the particles after heating was calculated using the following formula: The larger R2 is, the better the thermal stability is.
R2=100×(W ₅ /W ₄ )

<Preparation of Molded Product>
A composition was obtained by mixing 30 parts of the particles with 100 parts of polypropylene (MFR 2.4 g/10 min, density 0.90 g/cm ³ ).
Next, using a Laboplastomill (twin-screw extruder ME-25, manufactured by Toyo Seiki Kogyo Co., Ltd.) and a T-die (lip width 150 mm, thickness 0.7 mm), the set temperatures (molding temperatures) of the extruder and T-die were set to 200°C, and the screw rotation speed was set to 50 rpm.
The obtained composition was charged into a Labo Plastomill through a raw material hopper to produce a sheet as a molded article. The stickiness and odor of the surface of the produced sheet were evaluated.

<Flame retardancy of molded product>
The sheet prepared above was cut to prepare test pieces measuring 25 mm x 150 mm x 0.7 mm. These test pieces were subjected to a combustion test based on the UL-94 standard. The test piece was held vertically and exposed to a flame for 10 seconds at the bottom, and the combustion time after the flame was removed was evaluated.

<Temporal stability of molded body>
The sheet thus prepared was left standing at 40° C. for 60 days. After the standing, the stickiness and odor of the sheet surface were evaluated. The burning time was also evaluated by the same method as above.

Example 1
To 500 g of ion-exchanged water were added 120 g of sodium chloride, 30 g of colloidal silica containing 20% by weight of an active ingredient, 1 g of polyvinylpyrrolidone, and 0.1 g of ethylenediaminetetraacetic acid tetrasodium salt, and the pH of the resulting mixture was adjusted to 2.5 to 3.5 to prepare an aqueous dispersion medium.
Separately, an oily mixture was prepared by mixing 99 g of methacrylic acid, 1 g of ethylene glycol dimethacrylate, 3 g of 2,2'-azobis(isobutyronitrile), and 100 g of bisphenol A bisdiphenyl phosphate.
The aqueous dispersion medium and the oily mixture were mixed, and the resulting mixture was dispersed in a homomixer (TK homomixer, manufactured by Primix Corporation) at a rotation speed of 10,000 rpm for 1 minute. The mixture was then subjected to a polymerization reaction for 20 hours at a reaction temperature of 60°C while stirring at 150 rpm under an initial reaction pressure of 0.3 MPa. After polymerization, the polymerization product was filtered and dried to obtain particles 1. The average particle diameter of the obtained particles 1 was 20 μm. Furthermore, other physical properties of the particles were evaluated. The results are shown in Table 1.

(Examples 2 to 16 and Comparative Examples 1 to 3)
Particles (particles 2 to 19) were obtained in the same manner as in Example 1, except that the oily mixture was changed to that shown in Tables 1 and 2. The physical properties of each of the obtained particles were evaluated. The results are shown in Tables 1 and 2.

As can be seen from Tables 1 to 3, particles containing a shell including a polymer of polymerizable components including monomer (A) and monomer (B), in which monomer (a1) is essential, and a flame retardant encapsulated therein, exhibit excellent stability over time, with suppressed bleed-out of the encapsulated flame retardant. Furthermore, even when heated, the bleed-out of the encapsulated flame retardant is suppressed, with good thermal stability. Furthermore, molded articles containing the particles exhibit excellent stability over time.
On the other hand, in Comparative Example 2, which does not contain the monomer (A), Comparative Example 1, which does not contain the monomer (B), and Comparative Example 3, which does not contain the monomer (a1), the bleed-out of the flame retardant could not be suppressed, and the stability over time was poor.Furthermore, even when used in a molded article, the stability over time was poor.

1. Outer shell 2. Flame retardant

Claims (5)

A particle including an outer shell including a polymer and a flame retardant encapsulated therein,
The present invention excludes heat-expandable microspheres having an average particle size of 1 to 100 μm, which are composed of a shell made of a thermoplastic resin and a blowing agent encapsulated therein, the blowing agent having a boiling point equal to or lower than the softening point of the thermoplastic resin and containing a fluorine-containing compound, and heat-expandable microspheres obtained by a production method in which the heat-expandable microspheres are expanded by heating them to an expansion-initiation temperature or higher,
The polymer is a polymer of a polymerizable component containing the following monomer (A) and the following monomer (B),
the monomer (A) contains a carboxyl group- containing monomer (a1),
the carboxyl group-containing monomer (a1) contains methacrylic acid,
Particles , wherein the weight ratio of the monomer (A) in the polymerizable component is 50 to 99.99% by weight, and the weight ratio of the monomer (B) in the polymerizable component is 0.01 to 50% by weight .
Monomer (A): Monomer having one polymerizable carbon-carbon double bond Monomer (B): Monomer having at least two polymerizable carbon-carbon double bonds The particle according to claim 1 , wherein the monomer (A) further comprises the following monomer (a2):
Monomer (a2): at least one selected from nitrile-based monomers, (meth)acrylic acid ester-based monomers, monomers having a group reactive with a carboxyl group, and styrene-based monomers The particles according to claim 1 or 2 , wherein the flame retardant comprises at least one selected from an organic phosphorus compound, an organic halogen compound, and an inorganic compound. A composition comprising the particles according to any one of claims 1 to 3 and a base component. A molded article obtained by molding the composition according to claim 4 .