KR100740473B1 - Flame retardant compositions for flammable plastics and flame retarded plastic compositions containing the same - Google Patents

Abstract

A flame retardant composition is provided that is a flammable plastic flame retardant. This composition comprises a phthalocyanine or naphthalocyanine complex having a brominated flame retardant, a free-radical generating factor selected from 2,3-dimethyl-2,3-diphenyl-butane or its analogs, and a metal selected from groups 7 to 10 of the IUPAC Periodic Table. Include. The use of brominated flame retardants can be reduced by incorporating free-radical generators and phthalocyanine or naphthalocyanine complexes of this kind into combustible plastic materials.

Description

     Flame retardant compositions for flammable plastics and flame retardant plastic compositions containing the same

The present invention relates to flame retardant compositions for flammable plastics. The present invention also relates to a flame retardant plastic composition containing the flame retardant composition.

Various plastics or synthetic resins are used as parts or components of many electrical and electronic devices and appliances for reasons of good insulation, good water resistance, good moldability, and moderate mechanical strength. It is also used as a packaging and construction material. However, because most plastics are flammable, in many cases flame retardants are used for safety reasons. In many cases the level of flame retardancy required for plastic articles is standardized and has become increasingly stringent in recent years.

Plastics are typically flame retardant by incorporating brominated flame retardants and antimony trioxide into the plastic. However, there is a growing concern about carcinogens, such as dioxins, which occur when burning waste plastic articles containing brominated flame retardants. Attempts have been made to replace such brominated flame retardants with halogen-free flame retardants such as phosphate esters or ammonium polyphosphates. However, since halogen-free flame retardants are much less effective than brominated flame retardants, the use of halogen-free flame retardants in an amount sufficient to achieve the desired level of flame retardant inevitably weakens other essential properties such as formability and strength properties. As a result, there is a need for flame retardant compositions that allow for a drastic reduction in the amount of brominated flame retardant required to meet the flame retardant level of the desired plastic article, rather than when brominated flame retardants are used alone in plastic articles. Such compositions are advantageous because they enable the recycling of flame retardant plastic waste moldings in addition to being environmentally advantageous due to the low content of brominated flame retardants.

Thermoplastic polymers are known to be flame retardant by incorporating free-radical generators such as 2,3-dimethyl-2,3-diphenylbutane or dicumylperoxide. Free-radical generators selectively cleave the polymer's backbone to increase the flowability of the molten polymer, thereby helping the polymer to self-extinguish. By this principle, it is known to incorporate free-radical generators into combustible plastics together with brominated flame retardants and / or phosphate ester flame retardants to enhance flame retardancy or to reduce the amount of brominated flame retardant required. See JP-A-11 / 199784, JP-A-2001 / 181433, JP-A-2002 / 322323, JP-A-2003 / 160705, JP-A-2003 / 321584 and WO 00/12593. However, these conventional techniques are inflexible in terms of usable polymers and / or brominated flame retardants and require relatively large amounts of radical generators to achieve the desired level of flame retardancy.

Accordingly, there is still a need for flame retardant compositions and flame retardant plastic compositions that can reduce the amount of brominated flame retardants used while retaining sufficient flame retardant levels to pass various flame retardant tests.

The present invention provides a flame retardant plastic composition comprising a flammable plastic material and the flame retardant composition of the present invention in an amount corresponding to 0.5 to 25 parts by weight of the brominated flame retardant per 100 parts by weight of the combustible plastic material.

According to the invention, the amount of brominated flame retardant to achieve the desired flame retardant level can be significantly reduced compared to the case of using the brominated flame retardant alone. Thanks to the reduction in the amount of brominated flame retardants, many beneficial properties of the plastic material, such as molding and mechanical properties, are less damaged and environmental problems can be improved. In addition, waste generated during the manufacturing process can be recycled.

Summary of the Invention

This need can be met by providing a flame retardant composition for combustible plastics comprising the following materials according to the invention:

(a) brominated flame retardants having a bromine content of greater than 50% by weight;

(b) a free-radical generator selected from the group consisting of 2,3-dimethyl-2,3-diphenylbutane and its homologues;

(c) phthalocyanine complexes or naphthalocyanine complexes with metals selected from groups 7 to 10 of the IUPAC Periodic Table;

(Wherein, the weight ratio of (b) :( c) is 99: 1 to 1:99, and the sum of (b) + (c) per 100 parts by weight of (a) is 0.01 to 50 parts by weight.)

In a preferred embodiment, the free-radical generator is 2,3-dimethyl-2,3-diphenylbutane (DMDPB), 3,4-dimethyl-3,4-diphenylhexane, 4,5-dimethyl-4, 5-diphenyloctane, 3,4-diethyl-3,4-diphenylhexane, 4,5-diethyl-4,5-diphenyloctane, 2,3-dimethyl-2,3-di-p- Tolylbutane or 3,4-dimethyl-3,4-di-p-tolylhexane; At this time, the metal is Mn, Tc, Re, Fe, Ru, Os, Co, Rh, Ir, Ni, Pd or Pt.

In another preferred embodiment, the flame retardant composition comprises:

(a) brominated flame retardants having a bromine content of greater than 50% by weight;

(b) 2,3-dimethyl-2,3-diphenylbutane; And

(c) iron phthalocyanine;

(Wherein, the weight ratio of (b) :( c) is 95: 5 to 5:95, and the sum of (b) + (c) per 100 parts by weight of (a) is 0.05 to 15 parts by weight.)

In another aspect, the present invention provides a flame retardant plastic composition comprising a flammable plastic material and the flame retardant composition of the present invention in an amount corresponding to 0.5 to 25 parts by weight of the brominated flame retardant per 100 parts by weight of the combustible plastic material.

According to the invention, the amount of brominated flame retardant to achieve the desired flame retardant level can be significantly reduced compared to the case of using the brominated flame retardant alone. Thanks to the reduction in the amount of brominated flame retardants, many beneficial properties of the plastic material, such as molding and mechanical properties, are less damaged and environmental problems can be improved. In addition, waste generated during the manufacturing process can be recycled.

details

The present invention utilizes the synergistic effect of both free-radical generators and phthalocyanine or naphthalocyanine complexes to reduce the amount of brominated flame retardant used.

The term "2,3-dimethyl-2,3-diphenylbutane or its analogs" herein refers to 1,2-diphenyl-1,1,2,2-tetraalkylethane and each alkyl group in one or more benzene rings. It refers to derivatives thereof having one or more alkyl substituents containing 1 to 6 carbons. This compound, otherwise called a free-radical generator, is known to produce free radicals when heated above the processing temperature of most plastic materials. Therefore, this compound remains intact during processing such as extrusion molding, injection molding, compression molding, hot press lamination, and the like.

Copper phthalocyanine complexes such as phthalocyanine blue and phthalocyanine green are known as heat stable pigments and are used for the production of colored plastic articles. U. S. Patent No. 3,825, 520 discloses that incorporation of Fe, Cu, Mn, V and Co phthalocyanine into the styrene polymer together with octabromobiphenyl flame retardants may reduce smoke.

However, to the best of our knowledge, it is not known that metal phthalocyanine or naphthalocyanine is effective in reducing the amount of brominated flame retardants when incorporated into combustible plastic materials with free-radical generators.

(a) brominated flame retardants having a bromine content of greater than 50% by weight;

 Brominated flame retardants are well known in the art. Non-limiting examples are as follows.

Brominated alicyclic hydrocarbons:

Hexabromocyclododecane (HBCD), tetrabromocyclooctane (TBCO), monochloropentabromocyclohexane, and the like,

Brominated aromatic hydrocarbons:

Pentabromotoluene, hexabromobenzene, decabromodiphenylethane, brominated polystyrene, octabromotrimethylene group,

Brominated Phenyl Ether:

Decabromodiphenyl ether, octabromodiphenyl ether, hexabromodiphenyl ether, bis (tribromophenoxy) ethane, bis (pentabromophenoxy) ethane, poly (2,6-dibromophenylene oxide ) Etc,

Brominated bisphenols and derivatives thereof:

Tetrabromobisphenol A, Tetrabromobisphenol S, Tetrabromobisphenol F, Tetrabromobisphenol A Bis (2,3-dibromopropyl) ether, Tetrabromobisphenol S Bis (2,3-dibromo Propyl) ether, tetrabromobisphenol F bis (2,3-dibromopropyl) ether, tetrabromobisphenol A bis (2,3-dibromoisobutyl) ether, tetrabromobisphenol S bis (2, 3-dibromoisobutyl) ether, tetrabromobisphenol F bis (2,3-dibromoisobutyl) ether, tetrabromobisphenol A diallyl ether, tetrabromobisphenol S diallyl ether, tetrabromobis Phenol F diallyl ether, tetra bromobisphenol A dimethallyl ether, tetrabromobisphenol S dimethallyl ether, tetrabromobisphenol F dimethallyl ether, and the like,

Brominated Isocyanurate:

Tri (2,3-dibromopropyl) isocyanurate, tri (2,3-dibromoisobutyl) isocyanurate,

Other Brominated Flame Retardants:

Tetrabromophthalic anhydride, brominated polycarbonate, brominated epoxy resin, poly (pentabromobenzyl acrylate), ethylenebis (tetrabromophthalimide), 2,4,6-tris (2,4,6-t Libromophenoxy) -1,3,5-triazine, tris (tribromoneopentyl) phosphate,

(b) free- radical generators

As described above, the free-radical generator used in the present invention

2,3-dimethyl-2,3-diphenylbutane or its analogs. Examples of homologues are 3,4-dimethyl-3,4-diphenylhexane, 4,5-dimethyl-4,5-diphenyloctane, 2,3-dimethyl-2,3-di-p-tolylbutane and 3 , 4-dimethyl-3,4-di-p-tolylhexane. Preference is given to 2,3-dimethyl-2,3-diphenylbutane (dicumene).

(c) phthalocyanine Complexes and Naphthalocyanines Complex

The metal phthalocyanine complexes and naphthalocyanine complexes used in the present invention have the same or similar ligand structure as the copper phthalocyanine pigments. However, its central atom is selected from the Group 7-10 metal elements of the IUPAC periodic table instead of copper. Typically the central atom is Mn, Tc, Re, Fe, Ru, Os, Co, Rh, Ir, Ni or Pt. Co or Fe is particularly preferred. The central atom may also coordinate with halogen ions, typically chlorine ions. This phthalocyanine or naphthalocyanine ligand may have a substituent on the benzene ring, such as Cl, Br, alkyl, alkoxy, carboxyl or amino. Central metals other than the metal species described above, such as phthalocyanine complexes with Cu, Ti, Zn, V or Cr and naphthalocyanine complexes, when used alone or in combination with free-radical generators, have no or very small effect of reducing the amount of brominated flame retardants used.

The weight ratio of (b) :( c) in the flame retardant composition is 99: 1 to 1:99, preferably 90:10 to 10:90, more preferably 75:25 to 25:75. The ratio of (b) + (c) sum is 0.01 to 50, preferably 0.1 to 30, most preferably 0.2 to 20 parts by weight per 100 parts by weight of (a).

Flame retardant compositions of the invention are incorporated into combustible plastic materials. The amount of composition incorporated depends on the level of flame retardancy desired, the nature of the particular components (a), (b) and (c) and the presence or absence of auxiliary flame retardants such as antimony trioxide and / or halogen-free flame retardants such as ester phosphates. It can vary. The range of this mixing amount is generally 0.5 to 25 parts by weight, preferably 1.0 to 15 parts by weight per (a) per 100 parts by weight of the combustible plastic material. As mentioned above, this amount should not be exceeded if the desired level of flame retardancy is achieved.

The material of combustible plastics which will be flame retardant is mostly thermoplastics. Non-limiting examples include polystyrene, high impact polystyrene (HI-PS), styrene-butadiene copolymer, styrene-acrylonitrile copolymer, acrylonitrile-butadiene-styrene copolymer (ABS), polyethylene tetraphthalate (PET) , Polybutylene terephthalate, liquid crystalline polyester, polycarbonate, polyamide, polyphenylene oxide, modified polyphenylene oxide, polyphenylene sulfide, polyacetal, polyethylene, polypropylene, ethylene-vinyl acetate copolymer, ethylene -Propylene copolymer, ethylene-1-butene copolymer, ethylene-propylene-non-conjugated diene copolymer, ethylene-ethyl acrylate copolymer, ethylene-glycidyl methacrylate copolymer, ethylene-vinylacetate-glycidyl Methacrylate copolymers, maleic anhydride-modified ethylene-propylene copolymers, polyester-polyether elastomers Include polyester elastomer, and polymer blends thereof and polymer alloys, polyester-polyester elastomer, polyamide-polyether-elastomer, polyamide. Polystyrene, HI-PS, propylene, ABS, polycarbonates and polyamides are typical examples of plastics used in the mass production of plastic articles. The flame retardant composition of the present invention can be used in thermosetting plastics or resins. For example, the composition may be incorporated into a stack of unsaturated phenolic resins having a phenol, epoxy or paper or glass fiber substrate.

A portion of the brominated flame retardant (a) in this flame retardant composition can be replaced with a halogen-free phosphorus-based flame retardant to further reduce the amount of brominated flame retardant (a) used as long as the desired flame retardant level is met. Non-limiting examples of phosphorus flame retardants include triphenyl phosphate, tricrayl phosphate, trixylenyl phosphate, diphenylcresyl phosphate, trixylenyl phosphate, resorcinol-bis (diphenyl) phosphate, bisphenol A- Bis (diphenyl) phosphate, resorcinol-bis (dicresyl) phosphate, bisphenol A-bis (dicresyl) phosphate, resorcinol-bis (di-2,6-xylenyl) phosphate, Bisphenol A-bis (2,6-xylenyl) phosphate, phenoxyphosphazene, methylphenoxyphosphazene, xyleneoxyphosphazene, methoxyphosphazene, ethoxyphosphazene, proxyphosphazene, melamine polyphosphate, and Ammonium polyphosphate. Up to about 50% of these phosphorus-based flame retardants can replace brominated flame retardants.

The flame retardant plastic composition may optionally include other conventional additives. One such optional additive is an antioxidant such as antimony trioxide, antimony pentaoxide, tin oxide, zinc stannate, zinc stannate hydroxide, molybdenum oxide, ammonium molybdate, zirconium oxide, zirconium hydroxide, zinc Borate, zinc metaborate or barium metaborate. Most preferred is antimony trioxide. The amount of auxiliary flame retardant, if incorporated, may range from 0.1 to 10 parts by weight per 100 parts by weight of combustible plastic material. Examples of other conventional additives include heat stabilizers, antioxidants, UV absorbers, UV stabilizers, impact strength enhancers, pigments, fillers, lubricants, drip inhibitors, crystallne nuclei agents, release agents, antioxidants and compatibles. I am. Such conventional additives are well known in the plastics processing arts, and details can be found in various books related to plastics processing technology.

Once the foamed plastic article is envisioned, the blowing agent is optionally incorporated into the flame retardant plastic composition together with a foam nuclei agent or foam conditioning agent. Examples of blowing agents include volatile organic blowing agents such as propane, butane, pentane, hexane, 1-chloro-1,1-difluoroethane, monochlorodifluoromethane, monochloro-1,2,2,2-tetrafluoro Roethane, 1,1-difluoroethane, 1,1,1,2-tetrafluoroethane or 1,1,3,3,3-pentafluoropropane; Inorganic blowing agents such as water, nitrogen or carbon dioxide; And chemical blowing agents such as azo compounds. Typical examples of foam nucleating agents or foam conditioning agents are talc and bentonite. Depending on the nature of the foam desired, the amount of blowing agent may vary and is generally in the range of 0.005 to 0.7 moles per 100 g of plastic material.

The flame retardant plastic composition of the present invention can be produced by known methods. In the case of thermoplastic polymers, the flame retardant composition and any additives are melt-mixed using known instruments such as twin screw extruders, Barnbury mixers, laboplastomills or hot roll mills, followed by extrusion, injection molding or compression molding. Molded into the desired shape. The flame retardant composition and optional additives may be mixed together or separately. In the case of foam, the blowing agent can be injected directly into the molten plastic composition in the extruder. Alternatively, plastic beads containing a flame retardant and optional additives can be impregnated with a liquid blowing agent such as pentane and then heated with steam in the mold.

In the case of thermosetting plastics such as phenolic resins, flame retardants and optional additives may be incorporated with the curing catalyst into oligo-condensates or glazes and, if necessary, the mixture may be cast or laminate molded.

Example

The following examples of the invention should not be construed as limiting. All percentages and parts are by weight unless otherwise indicated.

The material used in the Example and the comparative example is as follows.

A. Plastic Material

A-1: High impact polystyrene produced by Toyo Styrene Co., Ltd. under the trademark TOYO STYROL H450

A-2: High impact polystyrene produced by Toyo Styrene Co., Ltd. under the trademark TOYO STYROL H650

A-3: Polypropylene produced by Sumitomo Chemical Co., Ltd. under the trademark SUMITOMO NOBLEN Y101S

A-4: A 70:30 mixture of polycarbonate produced by Idemitsu Petrochemical Co., Ltd. under the trademark TARFLON A 2000 and ABS produced by Toray Industires, Inc. under the trademark TOYOLAC.

A-5: Polyamide produced by Asahi Kasei Corporation under the trademark REONA 1300S

A-6: High density polyethylene produced by Idemitsu Petrochemical Co., Ltd under the trademark IDEMITSU HD130J

A-7: Polystyrene sold by Toyo Styrene Co., Ltd. under the trademark TOYO STYROL G220

A-8: Phenolic Resin Glaze

B. Brominated Flame Retardants

B-1: Tetrabromobisphenol A-bis (2,3-dibromopropyl) ether

B-2: tetrabromobisphenol A-bis (2,3-dibromoisobutyl) ether

B-3: tris (2,3-dibromopropyl) isocyanurate

B-4: tris (tribromoneopentyl) phosphate

B-5: 2,4,6-tris (2,4,6-tribromophenoxy) -1,3,5-triazine

B-6: decabromodiphenylethane

B-7: decabromodiphenyl ether

B-8: poly (2,6-dibromophenylene oxide)

B-9: hexabromocyclododecane (HBCD)

B-10: tetrabromobisphenol A epoxy oligomer

C. radical generator

2,3-dimethyl-2,3-diphenyllebutane

D. Phthalocyanine / Naphthalocyanine Complexes

D-1: iron phthalocyanine

D-2: iron phthalocyanine chloride

D-3: Cobalt Phthalocyanine

D-4: Iron Naphthalocyanine

D-5: Copper Phthalocyanine (Comparative)

D-6: titanium phthalocyanine (comparative)

E. Heat Stabilizers / Antioxidants

E-1: Dioctyl Maleate Polymer

E-2: pentaerythritol tetrabis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate

E-3: bis (2,6-di-t-butyl-4-methylphenyl) pentaerythritol diphosphite

F. Secondary Flame Retardants

Antimony trioxide

G. Foaming Agent

Pentane

H. Foam Nuclear Agents (Foam Conditioning Agents)

Talc commercially available from Nippon Talc Kogyo Co., Ltd

I. Phosphorus Flame Retardant

Triphenyl phosphate

Example 1-20 and Comparative Example 1-19

1. Preparation of Test Piece

According to the composition shown in Table 1-5, various materials were mixed and extruded using a twin screw extruder to prepare pellets. The pellet was then injection molded into test pieces of defined size. The temperatures of the heat cylinders of the extruder and the injection molding machine were adjusted as follows.

Thermal cylinder temperature, ℃

Plastic material Extruder Injection molding machine Inlet Outlet Inlet Outlet template A-1, A-3, A-6 80 200 180 200 40 A-4 80 260 240 260 80 A-5 80 300 280 300 80

2. Flame retardant test

Examples 1-16 and Comparative Examples 1-15 followed the vertical combustion method according to the UL-94 standard. The size of the test piece was 125 mm in length, 12.5 mm in width, and 3.2 mm in thickness. NR represents unevaluated.

In Examples 17-20 and Comparative Examples 16-18, the oxygen index (LOI) was measured according to the JIS K 7201 standard test.

3. Flexural Strength

Flexural stress was measured according to ASTM-D790.

4. Evaluation after recycling

The pellets were aged in an oven kept constant at 80 ° C. and 95% relative humidity for one week to prepare test pieces. The aged pellets were extruded again into pellets under the same conditions as above and injection molded into test pieces.

Darkening of the recycled test pieces was evaluated by the color difference ΔE of the test pieces corresponding to those used in the initial experiment. The flame retardancy test and flexural strength test described above were repeated for recycled specimens. Flexural strength is expressed as% retention relative to the specimens corresponding to those used in the initial experiment.

The recycling experiment was not performed on the test piece of the comparative example.

The results are shown in Table 1-6 below.

 As shown in Table 1-6, the flame retardancy of the formulations of Examples 1-20 was compared by incorporating the brominated flame retardant into the plastic material with a radical generator and a phthalocyanine / naphthalocyanine complex containing metals of groups 7-10 of the periodic table. Enhanced compared to Examples 1-19.

Examples 21-26 and Comparative Examples 20-23

1. Preparation of foam plastic test specimen

According to the composition shown in Table 7-8, various materials were fed to the two-stage tandem extruder except the blowing agent. In the first stage extruder having an internal diameter of 65 mm, the materials were heat mixed and extruded into a second stage extruder having an internal diameter of 90 mm. A predetermined amount of blowing agent was injected into the extrudate through a separate line at the front end of the first stage extruder under pressurized conditions. The extrudate from the first stage extruder was cooled to 120 ° C. in the second stage extruder and extruded through a die in the form of a ribbon having a width of 45 mm and a thickness of 2.5 mm.

2. Visual Evaluation of Foam Extruder

The condition of the resulting extrudate was visually evaluated according to the following criteria.

Good: A foamed extrudate without cracks or voids is obtained stably.

Poor: Stable extrusion is not possible because the foamed extrudate contains cracks or voids, or because of gas ejection from the die.

3. Flame retardant test

Oxygen index (LOI) was measured according to JIS K 7201 standard test.

4. Self-extinguishing

Yes = LOI greater than 26

None = LOI less than 26

5. Evaluation after recycling

The foamed extrudate produced in the initial extrusion was aged in an oven kept constant at 80 ° C. and 95% relative humidity for one week after breaking. The aged articles were blow extruded under the same conditions as above. The recycled extrudate was tested for state, oxygen index and self-extinguishing capacity. This recycling experiment was not performed for the extrudate of the comparative example. The results are shown in Table 7-8 below.

표 7-8에 나타난 바와 같이, 실시예 21-26의 발포 압출물은 난연성 및 거품 상태면에서 만족스러운 결과를 보였다. 비교예 20-23의 발포 압출물은 거품 상태가 양호했음에도 불구하고 자기-소화능을 지니지 않았다. 비교예 23의 발포 압출물은 인산염 에스테르와 함께 양을 증가시킨 브롬화 난연제 때문에 자기-소화능을 지니지만 다수의 크랙과 그을음이 관찰되었다.

As shown in Table 7-8, the foamed extrudate of Examples 21-26 showed satisfactory results in terms of flame retardancy and foam condition. The foamed extrudate of Comparative Examples 20-23 did not have self-extinguishing ability despite the good foaming condition. The foamed extrudate of Comparative Example 23 had self-extinguishing capacity due to the increased brominated flame retardant with phosphate esters, but numerous cracks and soots were observed.

delete

Examples and Comparative Examples 24-26

1. Preparation of Test Piece

According to the composition of Table 9, all additives were mixed with phenolic resin varnishes. The mixture was soaked in kraft paper and dried to prepare a prepreg. Eight prepregs were laminated at 150 ° C. in a 150 kgf / cm ² pressure heat presser for one hour to prepare a paper-phenolic resin laminate having a thickness of 1.6 mm.

2. Flame retardant test

The vertical combustion method according to the UL-95 standard was carried out using test pieces 125 mm long, 12.5 mm wide and 3.2 mm thick. The results are shown in Table 9 below.

As shown in Table 9, the laminate of Test Example 27-30 was enhanced flame retardancy compared to the laminate of Comparative Example 24-26.

According to the present invention, the amount of brominated flame retardant to achieve the desired level of flame retardant can be significantly reduced compared to the case of using the brominated flame retardant alone. Thanks to the reduction in the amount of brominated flame retardants, many beneficial properties of the plastic material, such as molding and mechanical properties, are less damaged and environmental problems can be improved. In addition, waste generated during the manufacturing process can be recycled.

Claims (15)

Flame retardant composition comprising: (a) brominated flame retardants having a bromine content of greater than 50% by weight; (b) a free-radical generator selected from the group consisting of 2,3-dimethyl-2,3-diphenylbutane and its homologues; And (c) phthalocyanine complexes or naphthalocyanine complexes with metals selected from groups 7 to 10 of the IUPAC Periodic Table; (Wherein the weight ratio of (b) :( c) is 99: 1 to 1:99, and the sum of (b) + (c) per 100 parts by weight of (a) is 0.01 to 50 parts by weight). The method of claim 1, wherein the free-radical generator is 2,3-dimethyl-2,3-diphenylbutane, 3,4-dimethyl-3,4-diphenylhexane, 4,5-dimethyl-4,5- Diphenyloctane, 3,4-diethyl-3,4-diphenylhexane, 4,5-diethyl-4,5-diphenyloctane, 2,3-dimethyl-2,3-di-p-tolylbutane Or 3,4-dimethyl-3,4-di-p-tolylhexane. The flame retardant composition of claim 1 wherein the metal is Mn, Tc, Re, Fe, Ru, Os, Co, Rh, Ir, Ni, Pd or Pt. The flame retardant composition of claim 1, wherein the ratio of (b) :( c) is 90:10 to 10:90. The flame retardant composition of claim 4, wherein the ratio of (b) :( c) is from 75:25 to 25:75. The flame retardant composition of claim 1, wherein the sum of (b) + (c) is 0.1 to 30 parts by weight per 100 parts by weight of (a). The flame retardant composition of claim 1 wherein the free-radical generator is 2,3-dimethyl-2,3-diphenylbutane and the metal of the complex is iron or cobalt. Flame retardant plastic composition comprising: (a) flammable plastic material; (b) 0.5 to 25 parts by weight of brominated flame retardant with a bromine content of more than 50% by weight per 100 parts by weight of the plastic material; (c) a free-radical generator selected from the group consisting of 2,3-dimethyl-2,3-diphenylbutane and its homologues; And (d) Phthalocyanine or naphthalocyanine complexes with metals selected from Groups 7 to 10 of the IUPAC Periodic Table: (The components (c) and (d) have a sum of (c) + (d) of 0.01 to 50 parts by weight per 100 parts by weight of (b) and a ratio of (c) :( d) of 99: 1 to 1: Present to be 99). 9. A flame retardant plastic composition according to claim 8, wherein the free-radical generator (c) is 2,3-dimethyl-2,3-diphenylbutane and the metal of the complex (d) is iron or cobalt. The flame retardant plastic composition of claim 8, wherein the combustible plastic material is a thermoplastic polymer. The flame retardant plastic composition of claim 10, wherein the thermoplastic polymer is polystyrene, polyolefin, polyamide, polycarbonate, copolymers or mixtures thereof. Molded plastic article made from a flame retardant plastic composition according to claim 8. Molded plastic article made from a flame retardant plastic composition according to claim 9. Molded plastic article made from a flame retardant plastic composition according to claim 10. Molded plastic article made from the flame retardant plastic composition according to claim 11.