Surface-coated flame-retardant particle and method of producing the same, and flame-retardant resin composition and method of producing the same

1. Surface-coated flame-retardant particles comprising a flame-retardant grain and a coated layer provided on a surface of the flame-retardant grain,

wherein the coated layer comprises an organic compound which has a binding group for combining with the flame-retardant grains at its terminal, or a polysilicone, the flame-retardant grain comprises a complex metal hydrate and has a volume average particle diameter of 1 to 500 nm, and the complex metal hydrate is represented by MgM x -(OH) y , wherein M represents one or more metals selected from the group consisting of Ca, Al, Fe, Zn, Ba, Cu, and Ni, x is a real number of 0.1 to 10, and y is an integer of 2 to 32; and

wherein the surface-coated flame-retardant particles have a degree of dispersion from 0.1 to 3.0, the degree of dispersion being defined by the following Formula (1):

Degree of dispersion=log( D 90 /D 10 )

where:

in a plot of a mass weighted cumulative distribution of the particles against particle weight from the smaller particle diameter side,

the particle diameter at which the cumulative distribution reaches the 90% point is designated as D 90 ; and

the particle diameter at which the cumulative distribution reaches the 10% point is designated as D 10 .

2. A flame-retardant resin composition comprising a matrix resin and surface-coated flame-retardant particles mixed with the matrix resin,

wherein the surface-coated flame-retardant particles each comprise a flame-retardant grain and a coated layer provided on a surface of the flame-retardant grain, the coated layer comprises an organic compound which has a binding group for combining with the flame-retardant grains at its terminal, or a polysilicone, the flame-retardant grains comprise a complex metal hydrate and have a volume average particle diameter of 1 to 500 nm, and the complex metal hydrate is represented by MgM x -(OH) y , wherein M represents one or more metals selected from the group consisting of Ca, Al, Fe, Zn, Ba, Cu, and Ni, x is a real number of 0.1 to 10, and y is an integer of 2 to 32; and

wherein the surface-coated flame-retardant particles have a degree of dispersion from 0.1 to 3.0, the degree of dispersion being defined by the following Formula (1):

Degree of dispersion =log( D 90 /D 10 )

where:

in a plot of a mass weighted cumulative distribution of the particles against particle weight from the smaller particle diameter side,

the particle diameter at which the cumulative distribution reaches the 90% point is designated as D 90 ; and

the particle diameter at which the cumulative distribution reaches the 10% point is designated as D 10 .

3. A method of producing surface-coated flame-retardant particles, the method comprising:

forming a dispersion liquid by dispersing flame-retardant grains in an aqueous solution in which a metal salt of an organic compound and a dispersant are dissolved; and

forming a coated layer by depositing the organic compound on the flame-retardant grains by adding an acidic aqueous solution to the dispersion liquid,

wherein the flame-retardant grains comprise a complex metal hydrate and have a volume average particle diameter of 1 to 500 nm, and the complex metal hydrate is represented by MgM x -(OH) y , wherein M represents one or more metals selected from the group consisting of Ca, Al, Fe, Zn, Ba, Cu, and Ni x is a real number of 0.1 to 10, and y is an integer of 2 to 32; and

wherein the surface-coated flame-retardant particles have a degree of dispersion from 0.1 to 3.0, the degree of dispersion being defined by the following Formula (1):

Degree of dispersion =log( D 90 /D 10 )

where:

in a plot of a mass weighted cumulative distribution of the particles against particle weight from the smaller particle diameter side,

the particle diameter at which the cumulative distribution reaches the 90% point is designated as D 90 ; and

the particle diameter at which the cumulative distribution reaches the 10% point is designated as D 10 .

4. A method of producing surface-coated flame-retardant particles, the method comprising:

forming a dispersion liquid by dispersing flame-retardant grains in a solution in which an organic compound and a dispersant are dissolved in an organic solvent miscible with water; and

forming a coating layer by depositing the organic compound on a surface of the flame-retardant grains by adding water to the dispersion liquid,

wherein the flame-retardant grains comprise a complex metal hydrate and have a volume average particle diameter of 1 to 500 nm, and the complex metal hydrate is represented by MgM x -(OH) y , wherein M represents one or more metals selected from the group consisting of Ca, Al, Fe, Zn, Ba, Cu, and Ni x is a real number of 0.1 to 10, and y is an integer of 2 to 32; and

wherein the surface-coated flame-retardant particles have a degree of dispersion from 0.1 to 3.0, the degree of dispersion being defined by the following Formula (1):

Degree of dispersion =log( D 90 /D 10 )

where:

in a plot of a mass weighted cumulative distribution of the particles against particle weight from the smaller particle diameter side,

the particle diameter at which the cumulative distribution reaches the 90% point is designated as D 90 ; and

the particle diameter at which the cumulative distribution reaches the 10% point is designated as D 10 .

5. A method of producing surface-coated flame-retardant particles, the method comprising:

forming a dispersion liquid by dispersing flame-retardant grains in an aqueous solution in which a dispersant is dissolved; and

adding an aqueous solution of a salt of a polyamino acid to the dispersion liquid so as to form a coating layer through deposition of the polyamino acid on the flame-retardant grains,

wherein the flame-retardant grains comprise a complex metal hydrate and have a volume average particle diameter of 1 to 500 nm, and the complex metal hydrate is represented by MgM x -(OH) y , wherein M represents one or more metals selected from the group consisting of Ca, Al, Fe, Zn, Ba, Cu, and Ni x is a real number of 0.1 to 10, and y is an integer of 2 to 32; and

wherein the surface-coated flame-retardant particles have a degree of dispersion from 0.1 to 3.0, the degree of dispersion being defined by the following Formula (1):

Degree of dispersion =log( D 90 /D 10 )

where:

in a plot of a mass weighted cumulative distribution of the particles against particle weight from the smaller particle diameter side,

the particle diameter at which the cumulative distribution reaches the 90% point is designated as D 90 ; and

the particle diameter at which the cumulative distribution reaches the 10% point is designated as D 10 .

6. A method of producing surface-coated flame-retardant particles, the method comprising:

forming metal soap particles having a micelle structure or a vesicle structure by dissolving a surfactant and a metal salt including MgM x -(OH) y , wherein M represents one or more metals selected from the group consisting of Ca, Al, Fe, Zn, Ba, Cu, and Ni, x is a real number of 0.1 to 10, and y is an integer of 2 to 32, in water;

converting the metal soap particles to reverse micelle particles by suspending the metal soap particles in an organic solvent; and

forming a complex metal hydroxide by allowing the metal ion contained in the reverse micelle particles to react with a base;

wherein the surface-coated flame-retardant particles have a degree of dispersion from 0.1 to 3.0, the degree of dispersion being defined by the following Formula (1):

Degree of dispersion =log( D 90 /D 10 )

where:

in a plot of a mass weighted cumulative distribution of the particles against particle weight from the smaller particle diameter side,

the particle diameter at which the cumulative distribution reaches the 90% point is designated as D 90 ; and

the particle diameter at which the cumulative distribution reaches the 10% point is designated as D 10 .

7. A method of producing surface-coated flame-retardant particles, the method comprising:

forming a suspension liquid obtained by suspending a metal salt of an organic compound in an organic solvent; and

forming a complex metal hydroxide by allowing the metal ion contained in the metal salt of the organic compound to react with a base,

wherein the metal salt of the organic compound includes MgM x -(OH) y , wherein M represents one or more metals selected from the group consisting of Ca, Al, Fe, Zn, Ba, Cu, and Ni, x is a real number of 0.1 to 10, and y is an integer of 2 to 32; and

wherein the surface-coated flame-retardant particles have a degree of dispersion from 0.1 to 3.0, the degree of dispersion being defined by the following Formula (1):

Degree of dispersion =log( D 90 /D 10 )

where:

in a plot of a mass weighted cumulative distribution of the particles against particle weight from the smaller particle diameter side,

the particle diameter at which the cumulative distribution reaches the 90% point is designated as D 90 ; and

the particle diameter at which the cumulative distribution reaches the 10% point is designated as D 10 .

8. A method of producing surface-coated flame-retardant particles, the method comprising:

forming a first aqueous solution in which a dispersant or chelate compound, and a metal salt of an organic compound are dissolved;

adding a second aqueous solution of a metal ion to the first aqueous solution; and

forming a complex metal hydroxide by adding a base to the mixed aqueous solution containing the metal ion,

wherein the metal salt of the organic compound includes MgM x -(OH) y , wherein M represents one or more metals selected from the group consisting of Ca, Al, Fe, Zn, Ba, Cu, and Ni, x is a real number of 0.1 to 10, and y is an integer of 2 to 32; and

wherein the surface-coated flame-retardant particles have a degree of dispersion from 0.1 to 3.0, the degree of dispersion being defined by the following Formula (1):

Degree of dispersion =log( D 90 /D 10 )

where:

in a plot of a mass weighted cumulative distribution of the particles against particle weight from the smaller particle diameter side,

the particle diameter at which the cumulative distribution reaches the 90% point is designated as D 90 ; and

the particle diameter at which the cumulative distribution reaches the 10% point is designated as D 10 .

9. A method of producing surface-coated flame-retardant particles, the method comprising treating flame-retardant grains having a volume average particle diameter of 1 to 500 nm with vapor of a cyclic organosiloxane compound so as to allow the cyclic organosiloxane compound to undergo ring-opening polymerization on the flame-retardant grains and so as to form a coating layer on the flame-retardant grains,

wherein the flame-retardant grains comprise a complex metal hydrate is represented by MgM x -(OH) y , wherein M represents one or more metals selected from the group consisting of Ca, Al, Fe, Zn, Ba, Cu, and Ni x is a real number of 0.1 to 10, and y is an integer of 2 to 32; and

wherein the surface-coated flame-retardant particles have a degree of dispersion from 0.1 to 3.0, the degree of dispersion being defined by the following Formula (1):

Degree of dispersion =log( D 90 /D 10 )

where:

in a plot of a mass weighted cumulative distribution of the particles against particle weight from the smaller particle diameter side,

the particle diameter at which the cumulative distribution reaches the 90% point is designated as D 90 ; and

the particle diameter at which the cumulative distribution reaches the 10% point is designated as D 10 .

10. A surface-coated flame-retardant particle produced by the method of claim 3 .

11. A surface-coated flame-retardant particle produced by the method of claim 4 .

12. A surface-coated flame-retardant particle produced by the method of claim 5 .

13. A surface-coated flame-retardant particle produced by the method of claim 6 .

14. A surface-coated flame-retardant particle produced by the method of claim 7 .

15. A surface-coated flame-retardant particle produced by the method of claim 8 .

16. A surface-coated flame-retardant particle produced by the method of claim 9 .

17. A method of producing a flame-retardant resin composition, the method comprising:

mixing at least a matrix resin and surface-coated flame-retardant particles; and

kneading the mixture by using at least one kneading machine selected from rolls, a kneader, a Banbury mixer, an intermixer, a uniaxial extruder, and a biaxial extruder,

wherein the surface-coated flame-retardant particles each comprise a flame-retardant grain and a coated layer provided on the flame-retardant grain, the coated layer comprises an organic compound or a polysilicone, the flame-retardant grains comprise a complex metal hydrate and have a volume average particle diameter of 1 to 500 nm, and the complex metal hydrate is represented by MgM x -(OH) y , wherein M represents one or more metals selected from the group consisting of Ca, Al, Fe, Zn, Ba, Cu, and Ni, x is a real number of 0.1 to 10, and y is an integer of 2 to 32; and

wherein the surface-coated flame-retardant particles have a degree of dispersion from 0.1 to 3.0, the degree of dispersion being defined by the following Formula (1):

Degree of dispersion =log( D 90 /D 10 )

where:

in a plot of a mass weighted cumulative distribution of the particles against particle weight from the smaller particle diameter side,

the particle diameter at which the cumulative distribution reaches the 90% point is designated as D 90 ; and

the particle diameter at which the cumulative distribution reaches the 10% point is designated as D 10 .

18. The surface-coated flame-retardant particle of claim 1 ,

wherein the surface-coated flame-retardant particles have a degree of dispersion from 0.1 to 1.0.

19. The surface-coated flame-retardant particle of claim 1 ,

wherein the surface-coated flame-retardant particles have a degree of dispersion from 0.1 to 0.8.

20. The flame-retardant resin composition of claim 2 ,

wherein the surface-coated flame-retardant particles have a degree of dispersion from 0.1 to 1.0.

21. The flame-retardant resin composition of claim 2 ,

wherein the surface-coated flame-retardant particles have a degree of dispersion from 0.1 to 0.8.