WO2001007500A1

WO2001007500A1 - Flame retardants, flame-retarded resin compositions and processes for making the same

Info

Publication number: WO2001007500A1
Application number: PCT/IL2000/000429
Authority: WO
Inventors: Yoav Bar-Yaakov; Arieh Kampf
Original assignee: Bromine Compounds Ltd.
Priority date: 1999-07-26
Filing date: 2000-07-20
Publication date: 2001-02-01
Also published as: AU6012400A; IL131124A0

Abstract

A flame retardant compound, which is a halogenated epoxy resin, having its epoxy groups blocked at least partially by halogenated bisphenol monoalkyl ether (HBPMAE). The flame retardant compound may be a brominated epoxy resin, having its epoxy groups blocked at least partially by brominated bisphenol monoalkyl ether. The flame retardant compound may have general formula (II) wherein Y is H or CH3, or is O if Z is S; Z is C or S; and X is Br or Cl, R1 is alkyl, R2 is alkyl or Glycidyl or -CH2-CHOH-CH2-OR3, R3 is alkyl, acyl or aryl, and n is from 1 to 100. R1 and R2 may be alkyl and X may be Br.

Description

FLAME RETARDANTS. FLAME-RETARDED RESIN COMPOSITIONS AND PROCESSES FOR MAKING THE

SAME

Field of the Invention

This invention relates to flame retardants, to thermoplastic or thermosetting resin compositions containing said flame retardants, and to processes for preparing said flame retardants and said thermoplastic resin compositions. The flame retardants of the invention are useful for a wide spectrum of thermoplastic resins, among them, in particular, polystyrene resins, polystyrene copolymers, ABS resins, polyolefin resins, polycarbonate resins, polyphenyl oxide resins, and alloys of polycarbonate resins and polystyrene resins and glass fiber reinforced resins.

Background of the Invention

Known flame-retarded thermoplastic resin compositions or flame retardants therefor include, for example, a flame retardant resin composition containing a halogenated epoxy resin as a flame retardant as disclosed in JP-A-5374557, JP-A-54-91557, JP-B-60-264313 and JP-A-62-15256 (the term " JP-A" as used herein means an "unexamined published Japanese patent application", and the term " JP-B" as used herein means an "examined Japanese patent publication"); a flame -retardant resin composition containing further a flame retardant synergist or co-flame retardant, e.g. antimony trioxide, as disclosed in JP-A-62-15256; and a flame retardant system comprising a combination of a brominated bisphenol compound, an epoxy compound and a metallic soap, e.g. calcium stearate. However, since the conventionally proposed flame retardants have high stickiness to metallic parts of a molding machine* or a mold, especially in the presence of antimony trioxide, compounding of such flame retardants causes reduction in releasability of a molded article from a mold. Besides, the flame retardant, that sticks and remains on the metallic parts, undergoes thermal decomposition, causing discoloration or scorching.

It is believed that a high concentration of epoxy groups and hydroxyl groups in the flame retardant is the cause for metal adhesion. The flame retardant (FR.) remaining on the metallic parts undergoes thermal decomposition and cause discoloration or scorching.

Another problem related to this composition is a reduced impact resistance of the thermoplastic compositions.

JP-A-62-473 discloses flame retarded thermoplastic compositions comprising an epoxy resin whose epoxy groups are blocked by halogenated phenol compound, e.g., tribromophenol. These compositions have lower stickiness to metallic parts of the injection molding machine and better impact resistance, but they have lower resistance to discoloration when exposed to UV radiation or to sun radiation.

U.S. Patent No. 5,336,735 discloses a flame-retarded thermoplastic composition which has reduced stickiness to metallic parts and which is made of a halogenated epoxy resin whose epoxy groups are blocked by a long chain aliphatic carboxylic acid. This flame retardant contains a lower concentration of halogen atoms and its flame retardant efficiency is reduced. JP-A-07.300546 discloses a flame retardant which is halogenated epoxy resin having epoxy groups partially or wholly blocked with C<8 mono carboxylic acids or C<8 mono alcohols or mono phenols or alkylphenols in these flame retardants: there is also reduced halogen atoms concentration which reduces flame retardant efficiency.

Summary of the Invention

The present invention relates to flame retardants, to thermoplastic or thermosetting resin compositions containing said flame retardants, and to processes for preparing said flame retardants, which feature increased thermal stability and reduced discloration under exposure to UV or sun radiation and reduced metal adhesion. The flame retardants according to this invention are characterized in that they contain as flame retardant a halogenated (preferably, but not exclusively, brominated) epoxy resin, whose epoxy groups are wholly or partially blocked by halogenated bisphenol monoalkyl ether (designated hereinafter as HBPMAE).

Additionally, the flame retardant may comprise other halogenated organic flame retardants.

The HBPMAE has the general formula

wherein Y is H or CH3, or is O when Z is S,

Z is C or S;

X is halogen, preferably bromine but also chlorine.

The alkyl is preferably methyl.

The bonds between Z and Y are simple bonds if Z is C, and double bonds if Z is S.

If the halogenated epoxy resin is based on tetrahalobisphenol, the flame retardant compound of the invention has the general formula:

wherein

Ri = -Alkyl or glycidyl, or

R₂ = -Alkyl

R3 = alkyl, acyl groups or aryls

X = Br or Cl n = 1 ÷ 100

Z and Y have the meanings set forth in formula (I).

If the halogenated epoxy resin is not based on tetrahalobisphenol, the n repetitive units will change accordingly. Formula II represents a mixture of molecules having different molecular weights, "n" should be read as an average value of repeating units.

The thermoplastic resins which can be used in the present invention include polystyrene resins, polystyrene copolymers, acrylonitrile butadiene styrene copolymer (ABS resins), styrene acrylonitrile copolymer (SAN), polyolefin resins, e.g., polyethylene and polypropylene, polyester resins, e.g., polybutylene terephthalate (PBT) and polyethylene terephthalate (PET), polycarbonate resins, polyamide resins, polyphenylene oxide (PPO) resins, alloys of polycarbonate resins and polyester resins, and alloys of polycarbonate resins and polystyrene resins.

The flame retardant of the present invention can be applied also to thermosetting resins, such as epoxy resins, unsaturated polyester resins, phenolic resins and polyurethane resins.

When compounded with the resins, the flame retardant of the present invention is used in an amount usually of from 1 to 50 parts by weight per 100 parts by weight of the resin. Amounts between 5 and 30 parts by weight of flame retardant per 100 parts by weight of the resin are particularly preferred for obtaining high flame retardancy and minimizing reductions in physical properties such as impact resistance.

The invention also comprises preparing the flame retardant of the invention by reacting the halogenated epoxy with the alkyl ether of halogenated bisphenol (HBPMAE). Alternatively it can be prepared by alkylating on the phenolic end groups of a halogenated epoxy resin having free phenolic end groups, or by reacting the HBPMAE and possibly halogenated bisphenol with epichlorohydrine in the presence of a base, or by other process that will be described hereinafter.

An example of the reaction of the halogenated epoxy with HBPMAE, wherein the halogen is bromine and the HBPMAE is the monomethyl ether of tetrabrominated bisphenol A (hereinafter TBMM), is:

wherein F-2200 indicates diglycidyl ether of TBBA and m = ca. 1.

Detailed Description of Preferred Embodiments

The halogenated epoxy resin which can be used in the present invention includes, but is not limited to, halogenated bisphenol type epoxy resins, halogenated cresol novolac type epoxy resins, halogenated hydroquinone type epoxy resins, halogenated bisphenol A novolac type epoxy resins, and halogenated resorcinol novolac type epoxy resins. Among them, halogenated bisphenol type epoxy resins having an average degree of polymerization of from 0 to about 50 are usually preferred.

The preferred degree of polymerization depends on the composition of the thermoplastic or thermoset. Thus, for thermosetting compositions, a low degree of polymerization is usually preferred, while for engineering thermoplastics such as polyesters and polyamide, a higher degree of polymerization is preferred. The cost of production also differs, generally with production of a product having a higher degree of polymerization being more expensive.

Examples of halogenated bisphenol compounds constituting the halogenated bisphenol type epoxy resins are dibromobisphenol A, tetrabromobisphenol A, dichlorobisphenol A, tetrachlorobisphenol A, dibromobisphenol F, tetrabromobisphenol F, dichlorobisphenol F, tetrachlorobisphenol F, dichlorobisphenol S, tetrachlorobisphenol S, tetrabromobisphenol S, and dibromobisphenol S.

Preferable halogenated bisphenols are brominated bisphenols. Examples of said bisphenols are:

Tetrabromobisphenol F Tetrabromobisphenol S

(TBBF)

and TBBA Tetrabromobisphenol A

Examples of the alkyl group constituting the alkyl ethers of halogenated bisphenol are methyl, ethyl, propyl, isopropyl, butyl, pentyl, hexyl heptyl, octyl, allyl, halogenated alkyls, etc.

Phenols may be O-alkylated to afford arylalkyl ethers by the classical Williamson reaction (see Feuer and Hooz in Patai, The

Chemistry of the Ether Linkage: Wiley: New York, 1967, pp. 446-450 and 460-468): base ArOH + RX - ArOR

The usual practical method involves treatment of a phenolate, prepared from the phenol and base in an appropriate solvent with an alkylating agent, most frequently with an alkyl halide (X = Cl, Br, I). Other alkylating agents used are dialkyl sulfates: mostly dimethyl and diethyl sulfates. Arylalkyl ethers can also be made by reacting an aryl acetate with an alkyl halide in the presence of potassium carbonate and a crown ether (see Banerjee, Gupta, Singh, J. Chem. Soc. Chem. Commun. 1982, 815). Other reagents have also been used (for a list of reagents used to convert phenols into ethers, see Larock, Comprehensive Organic Transformations, VCH: New York, 1989, pp. 446-448).

Methyl ethers of phenols may be prepared by the reaction of the phenolate with one of the following reagents: dimethyl sulfate (see in Paquette [editor], Encyclopedia of Reagents for Organic Synthesis, Wiley: Chichester, 1995, Vol. 3, pp. 2132 - 2135), methyl chloride (see, for example, in OLS 23 38 811 [1975], the preparation of various aryl methyl ethers, methyl bromide (see, for example, EP-A-0 353 755 [1989] and methyl iodide (see in Paquette [editor], Encyclopedia of Reagents for Organic Synthesis, Wiley: Chichester, 1995, Vol. 4, pp. 2828-2832).

Methyl ethers of TBBA have been mentioned in the Hterature: the dimethyl ether is mentioned in OLS 2 041 745 (method of preparation not disclosed), and the monomethyl ether is mentioned in EP-A-0 497 465 (prepared by the reaction of a dimethyl sulfate solution in ether with a solution of TBBA in aqueous sodium hydroxide - 19% yield).

The halogenated epoxy resin whose epoxy groups are blocked by HBPMAE can be obtained through various processes.

All processes are variations of the same basic reactions, in which:

1 - Halogenated polyphenols or bisphenols or alkylated halogenated polyphenols or bisphenols are reacted with epichlorohydrine in the presence of an acid acceptor to produce halogenated epoxy resin, or HBPMAE modified epoxy resin.

2 — Epoxy resin is reacted with halogenated polyphenols or bisphenols or alkylated halogenated polyphenols or bisphenols or their mixtures to give a higher molecular weight product.

3 - Halogenated polyphenols or bisphenols or epoxy resins made of halogenated polyphenols or bisphenols and having free phenolic groups are alkylated. The three reactions may be performed at different sequences and different reactant concentrations to obtain products* with the desired properties.

For example:

1. Reacting halogenated epoxy resin with HBPMAE in the presence or absence of halogenated bisphenol, by heating with or without a catalyst. The concentration of the epoxy groups in accordance with this process should be equal to or higher than the concentration of phenol groups from both HBPMAE and the halogenated bisphenol to prevent the presence of free phenolic groups in the final product. The molecular weight of the halogenated epoxy resin and the molar ratio of the three components will determine the number of repeating groups n in formula II.

2. Reacting a mixture of halogenated bisphenols and HBPMAE with epichlorohydrine and an acid acceptor such as alkali metal hydroxides.

3. Alkylating an halogenated epoxy resin having phenolic end groups end groups.

4. Reacting HBPMAE with epichlorohydrine and an acid acceptor such as alkali metal hydroxides, and reacting the product with halogenated bisphenol, and/or HBPMAE.

More specifically:

Process No. 1 comprises reacting a halogenated epoxy resin with i) a

HBPMAE and ii) optionally a halogenated bisphenol in the presence or absence of catalyst by heating at 80°C to 250°C. The concentration of the epoxy groups should be equal to or higher than the concentration of the phenolic groups to prevent the presence of free phenolic groups in the final product.

Process No. 2 comprises reacting epichlorohydrine with i) a halogenated bisphenol and ii) a HBPMAE in the presence of an acid acceptor such as alkali metal hydroxide at a temperature from 25°C to 120°C and then reacting the reaction product in the presence or absence of catalyst at 80°C to 250°C.

Process No. 3 comprises alkylating phenolic end group of halogenated epoxy resin (D) having an end group of halogenated bisphenol with a free phenol group. The halogenated epoxy resin D may be obtained through various processes. For example, it can be obtained by reacting halogenated epoxy resin with excess halogenated bisphenol in the presence or absence of catalyst at a temperature of 80°C-120°C, or a process comprising reacting halogenated bisphenol with epichlorohydrine in the presence of alkali metal hydroxide in such a way that the phenol group concentration is higher than the epoxy group concentration.

Process No. 4 comprises reacting epihydrochlorin with HBPMAE and possibly halogenated bisphenol in the presence of an acid acceptor such as alkali metal hydroxide at a temperature of 25°C-120°C, and then reacting the reaction product with halogenated bisphenols in the presence or absence of catalyst at a temperature of 80°C-250°C. An example of this process is illustrated in the following reaction scheme:

Some steps of this reaction are usually carried out in a solvent which is an organic solvent such as an aromatic solvent, ketone, alcohol, etc.

Catalysts which can be used in the above-described reactions include alkali metal hydroxides, e.g., sodium hydroxide, tertiary amines, e.g., dimethylbenz lamine, imidazoles, e.g.,

2-ethyl-4-methylimidazole, quaternary ammonium salts, e.g., tetramethylammoniumchloride, phosphonium salts, e.g., ethyltriphenylphosphoniumiodide, and phosphines, e.g., triphenylphosphine .

If desired, the resin composition according to the present invention may further contain flame retardant assistants to increase flame retardancy. Examples of useful flame retardant assistants include antimony compounds, e.g., antimony trioxide, antimony tetroxide, and antimony pentoxide; tin compounds, e.g., tin oxide and tinhydroxide; molybdenum compounds, e.g., molybdenum oxide and ammonium molybdate; zirconium compounds, e.g., zirconium oxide and zirconium hydroxide; and boron compounds, e.g., *zinc borate and barium metaborate, silicon compounds such as silicon oil, fluorine compounds such as polytetrafluoroethylene.

When the flame retardant assistants are added to the resin composition according to the present invention, their content is preferably 0.5 to 10 wt% of the whole composition.

The resin composition may also contain known flame retardants, as long as the improving effects on thermal stability during molding and mold releasability during injection molding are not considerably lessened. The resin composition may furthermore contain, if desired, other compounding additives, such as ultraviolet absorbers, light stabilizers, release agents, lubricants, colorants, plasticizers, fillers, blowing- agents, heat stabilizers, antioxidants, and reinforcements (e.g., glass fiber, carbon fiber, aramid fiber).

The resin composition can be easily prepared by pre-mixing prescribed amounts of a thermoplastic resin and a flame retardant and, if desired, other compounding additives in a mixing machine, e.g., a Henschel mixer and a tumble mixer, and then melt mixing in an extruder, a kneader, a hot roll, a Banbury mixer, etc.

Having excellent thermal stability on molding and excellent mold releasability, the flame retardant thermoplastic resin composition according to the present invention affects molded articles of good appearance. The easy release shortens a required molding time, leading to an increase in productivity of molding. Further, since the flame retardant according to the present invention has reduced stickiness to the metallic parts of a molding machine or a mold and also does not easily decompose under heating, it endows a thermoplastic resin composition with satisfactory thermal stability and mold releasability when compounded therein.

The following examples illustrate the invention, but do not limit it in any way. All the percents and parts are by weight, unless otherwise indicated.

Example 1 Preparation of a mixture of TBBA. TBMM and TBDM

The following reagents were fed into a round-bottomed flask: methanol (1500 ml), tetrabromo bisphenol A (TBBA) (544 g - 1 mole) and a 20% sodium hydroxide solution in water, 1 mole of NaOH). The mixture was stirred and warmed to 35°C. A stream of gaseous methyl bromide (90 g - 0.95 moles) was fed into the mixture during two hours, keeping the temperature at 35°C. Stirring was continued for an additional two hours at the same temperature.

Water (600 g) was added to the reaction mixture. Methanol was recovered by distilling it out (the recovered solvent contained ca. 11% water and could be reused in subsequent reactions without any treatment by adjusting the water content of the NaOH solution). The resulting aqueous slurry was acidified with an 18% hydrochloric acid (54 g) and filtered. The solid product was thoroughly washed by suspending it in water and stirring at 90° C for one hour. The product was isolated from the warm suspension by filtration. The wet cake was dried under reduced pressure (40 mm Hg) at 70°C to yield 570 g product (composition: tetrabromo bisphenol A monomethyl ether (TBMM) - 57%, tetrabromo bisphenol A dimethyl ether (TBDM)- 11.9%, TBBA - 28.7%.

Example 2 Preparation of methyl terminated brominated epoxy resins

This example carries out the process No. 4.

Step 1: to a round-bottomed 2 liter, 5-necked flask equipped with mechanical stirrer, thermometer, reflux condenser and feeding port, the following reagents were added:

- 100 g Epichlorohydrine.

- 500 g mixture of TBBA 21.5%, TBMM 57.2% and TBDM 18.2%

- 15 g methanol

- 2 g tetra methyl ammonium chloride

The content was heated to reflux temperature of 85° for 3 hours, at which time 300 g of toluene and 207 g of 25% solution of NaOH in water was added. The mixture was heated for 4 more hours at 85°C. The material was cooled to 50°C and stirring stopped. The aqueous phase was removed and the residue was washed twice with fresh water. The organic material was filtered and the solvent was removed by heating to 130°C under vacuum. The product obtained was a yellow liquid having epoxy equivalent weight (EE) of 606 g/eq.

Chain Extension

Into a 1 -liter round bottom resin flask, the following materials were fed:

- 264 g product of step 1

- 182 g mixture of TBBA 45%, TBMM 50.7%, TBDM 3.1%

- 0.9 g Triethylbutyl ammonium bromide (TEBAB).

The content was heated while stirring to 150°C for 6 hours, poured into a stainless tray, allowed to cool to room temperature and ground. The resulting product was off-white powder having epoxy equivalent weight of 7164 g/equ. Free phenohc group: 0.007 mmol/g and an average molecular weight of 1450.

TBDM is present together with TBMM, but it does not participate in the reaction and is included in the final product with the desired product of general formula II: wherein:

X = Br

Ri = Methyl

R2 = Methyl or glycidyl n = 1.5.

Example 3 Preparation of modified epoxy from epoxy and methylated TBBA.

This example carries out process no. 1. To a round bottom resin flask equipped with a thermometer, stirrer and heating mantel, the following materials were charged:

- 1600 g F-2200 (brominated epoxy resin ex Dead Sea Bromine Compounds — DSB, which consists mainly of diglycidyl ether of tetrabromobisphenol A, having an epoxy equivalent weight of 342).

- 1534 g mixture of TBBA 19%, TBMM 56%, TBDM 25%.

- 404 g - TBBA

- 1 g Tetrabutyl Phosphoniun Bromide (TBPBr).

The mixture was heated to 165°C for 5 hours, then poured into stainless trays cooled and ground. The obtained material was a pale yellow powder having the following properties: Epoxy equivalent weight - 10809 g/eq Weight average MW - 4523 NO average MW - 2140 Softening point - 138.4°C.

Example 4 Preparation of methyl terminated epoxy resin via one-pot process

The one-pot process according to process No. 2. TBBA was partly methylated with MeBr and then reacted with epichlorohydrine in the presence of sodium hydroxide. To a round-bottomed 2 liter,

5-necked flask equipped with mechanical stirrer, thermometer, reflux condenser and a dip pipe, the following reagents were added:

TBBA - 544 g

Methanol - 544 g

40% solution of sodium hydroxide - 88 g

The temperature was set to 20°C, and then 80 g of methyl bromide was added through the dip pipe in 60 minutes. The temperature was raised gradually to 60°C in two hours. The TBBA derivatives were analyzed by gas chromatograph, and the following distribution was found:

TBBA - 30.5%

TBMM - 51%

TBDM - 16%

The temperature was raised to 80° C as some of the methanol was distilled off. 1.6 g of triethylbutyl ammonium bromide and 68.6 g epichlorohydrine was added. The reaction mixture was refluxed for two hours and 400 g of toluene and 100 g of 40% solution of sodium hydroxide was added and refluxed for two additional hours. 800 g water was added. Stirring was stopped, and the two phases were separated. The aqueous phase was removed and the washing step was repeated three times.

1 g of tetrabutylphosphonium bromide was added and the mixture was heated to 150°C, distilling off the toluene. Vacuum was applied at the end for two hours. The product was poured into a stainless tray, cooled and ground.

The resultant product was pale yellow powder having the following properties:

Epoxy equivalent weight 17000

Weight average MW 2798

NO average MW 1529

Softening point 116.1

Color Gardner 50% solution in Dioxan 1

The preparation of flame-retarded resin compositions according to the invention and the properties of said compositions are illustrated hereinafter.

In the examples illustrating said preparation and properties, the following preparation conditions and test methods were employed:

Specimens preparation

All components were weighed in a polyethylene bag and mixed manually. The mixture was fed to ZE25 co-rotating twin-screw extruder L/D = 32 ex Berstorff at the following temperatures: 40-180-190-200-210-210-210-210°C. The compounded extrudate was cut to pellets. The obtained pellets were dried in an air circulating oven at a temperature of 80°C for three hours. The dried pellets were injection-molded using Allrounder 221-75-350 injection press ex. Arburg at temperatures 180-220-240-240°C and mold temperature -40°C.

Test methods

The test methods are presented in Table I.

Table I

Weather ability was evaluated as color change DE after light exposure.

Two kinds of exposure were used:

- sun exposure of specimens oriented toward the south at 45°;

- QUV exposure under B-340 lamps in Accelerated Weathering Tester.

Processing heat stability was evaluated as color difference DE before and after stopping the injection molding for 5 min. and then continuing the molding.

Adhesion of the compounds was evaluated by special laboratory test. This test is based on the measurement of lap shear force between two aluminium bars and the tested plastic compound between them.

Specimens for this test were prepared in the following way, compounding in Plasti-Corder with consequent pressing under heat of Al/plastic/Al sandwich of 30 mm x 15 mm at 220°C and 30 bar during 2 minutes.

Table II summarizes comparative test results of ABS resin flame retarded in accordance with the present invention.

In this table, F2000M is the FR of formula II according to the present invention, wherein:

The bisphenol is TBBA Rl = R2 = methyl X = Br

Y = Methyl

Z = C

N = 2.1 for Exl and 1.5 in Ex. 2.

F2016 is non-modified epoxy based on TBBA, sold by DSBG.

F 3020 is modified brominated epoxy and is capped with tribromophenol sold by DSBG.

Table II Properties of flame retarded general purpose ABS

* MASTER BATCH containing 80% antimony trioxide

In this table one can see the improved impact of new FRs with respect to non-modified brominated epoxy F-2016 and improved hght stability compared with TBP modified epoxy F-3020.

The following examples and comparative examples demonstrate the use of the flame retardants of the invention in glass fiber reinforced Polybutylene terephthalate (PBT). Specimen preparation

All components except glass fiber were weighed in a polyethylene bag and mixed manually. The mixture was fed by loss in weight gravimetric feeder to the main feeding port of the twin screw extruder. Glass fibers were fed to the 5^th section of the extruder via lateral feeding. The extruder was heated to the following temperatures:

Compounded extrude was cut to pellets. The obtained pellets were dried in an air-circulating oven at 100°C for 4 hours.

The dried pellets were injection-molded, using Allrounder 221-75-350°C at temperatures 250-260-260-275 and mold temperature 120°C.

The specimens were tested according to the test methods described. Compositions of the plastic material and test results are presented in the following tables:

Materials used

M.B. means Master Batch. EMA means Ethylene-Methylmethacrylate

Copolimer.

Formulations

* Formulation 5 was prepared from a 50%/50% mix of pellets from formulations 3 and 4.

Test Results

Δ DE means difference in DE, viz. DE1-DE2. N/mm² means Newton per square millimeter. From these tables, one can see the glass fiber reinforced PBT, flame retarded with the flame retardants of this invention, has excellent properties, when compared with the same resin flame retarded with high molecular weight brominated epoxy resin, namely:

- higher melt flow, as can be seen from the higher MFI;

- excellent flammability - V-0 rating according to the UL-94 test;

- good mechanical properties;

- good UV stability; and

- good thermal stability. While a number of examples have been described for illustrative purposes, they are not limitative and the invention may be carried out with many modifications and variations, without exceeding the scope of the claims.

Claims

1. A flame retardant compound, which is a halogenated epoxy resin, having its epoxy groups blocked at least partially by halogenated bisphenol monoalkyl ether (HBPMAE).

2. A flame retardant compound according to claim 1, which is a brominated epoxy resin, having its epoxy groups blocked at least partially by brominated bisphenol monoalkyl ether.

3. A flame retardant compound according to claim 1, having the general formula

wherein Y is H or CH3, or is O if Z is S; Z is C or S; and X is Br or Cl, Rl is alkyl, R2 is alkyl or Glycidyl or -CH2-CHOH-CH2-OR3 , R3 is alkyl, acyl or aryl, and n is from 1 to 100.

4. A flame retardant compound according to claim 3, wherein Ri and R2 are alkyl and X is Br.

5. A flame retardant compound according to claim 3 wherein Z = C and Y = CH₃.

6. A flame retardant compound according to claim 1, wherein the HBPMAE is chosen from among Tetrabromobisphenol F and Tetrabromobisphenol S and Tetrabromobisphenol A.

7. A flame retardant compound according to claim 1, wherein the halogenated epoxy resin is chosen from the group consisting of halogenated bisphenol type epoxy resins, halogenated cresol novolac type epoxy resins, halogenated hydroquinone type epoxy resins, halogenated bisphenol A novolac type epoxy resins, and halogenated resorcinol novolac type epoxy resins.

8. A flame retardant compound according to claim 7, wherein the halogenated epoxy resin is an halogenated bisphenol resin having an average degree of polymerization of from 0 to 50.

9. A flame retardant compound according to claim 8, wherein the halogenated epoxy resin is made of bisphenols chosen from the group consisting of dibromobisphenol A, tetrabromobisphenol A, dichlorobisphenol A, tetrachlorobisphenol A, alkyl ethers, dibromobisphenol S, dibromobisphenol F, tetrabromobisphenol F, tetrabromobisphenol S, dichlorobisphenol F, tetrachlorobisphenol F, dichlorobisphenol S, and tetrachlorobisphenol S.

10. A flame retardant compound according to any one of claims 6 to

9, wherein the halogenated epoxy resin is made of Tetrabromobisphenol A (TBBA).

11. A flame retardant compound according to any one of claims 3 to

10, wherein the alkyl groups constituting the alkyl ethers of halogenated bisphenol are chosen from the groups consisting of methyl ethyl, propyl, isopropyl, butyl, pentyl, hexyl heptyl, octyl, allyl, and halogenated alkyls.

12. A flame retardant compound according to any one of claims 1 to 11, further comprising an additional flame retardant.

13. A flame retardant compound according to claim 12, wherein the additional flame retardant is tetrabromobisphenol A dimethylether.

14. A flame retardant compound, comprising a thermoplastic or thermosetting resin and flame retardant according to any one of claims 1 to 13.

15. Flame retarded composition according to claim 14, comprising a thermoplastic resin chosen from the group consisting of polystyrene, high impact polystyrene, ABS resins, polyacrylonitrile resins, styrene acrylonitrile resins, polyolefin resins, polyester resins, polycarbonate resins, polyamide resins, polyphenylene oxide (PPO) resins, alloys of PPO resins and polystyrene, alloys of polycarbonate resins and polystyrene alloys of polycarbonate resins and polyester resins, and alloys of polycarbonate resins and polyamide resins.

16. Flame retarded composition according to claim 14, comprising a thermosetting resin chosen from the group consisting of epoxy resins, unsaturated polyester resins, phenolic resins and polyurethane resins.

17. Flame retarded composition according to claim 14, wherein the flame retardant is in an amount from 1 to 50 parts by weight per 100 parts by weight of the resin.

18. Flame retarded composition according to claim 17, wherein the flame retardant is in an amount from 5 to 30 parts by weight per 100 parts by weight of the resin.

19. Flame retarded composition according to claim 14, further comprising flame retardant assistants chosen from the group consisting of consisting of antimony compounds, tin compounds, molybdenum compounds, zirconium compounds, boron compounds, silicon compounds and fluorine compounds.

20. Flame retarded composition according to claim 19, wherein flame retardant assistants are comprised in an amount of 0.5 to 10 wt% of the total composition.

21. Flame retarded composition according to claim 14, further comprising additives chosen from the group consisting of ultraviolet absorbers, light stabilizers, release agents, lubricants, colorants, plasticizers, fillers, blowing agents, heat stabilizers, antioxidants, and reinforcements.

22. Process for making a flame retardant compound according to claim 1, carrying out in any order the steps of:

a) reacting a halogenated polyphenol or bisphenol or an alkylated halogenated polyphenol or bisphenol with epichlorohydrine in the presence of an acid acceptor to produce halogenated epoxy resin, or HBPMAE modified epoxy resin; b) reacting halogenated epoxy resin with a halogenated polyphenol or bisphenol or an alkylated halogenated polyphenol or bisphenol or their mixture to give a higher molecular weight product;

c) halogenated polyphenols or bisphenols or epoxy resins made of halogenated polyphenols or bisphenols and having free phenolic groups are alkylated.

23. A process for making a flame retardant compound according to claim 1, which comprises reacting a halogenated epoxy resin with i) a HBPMAE and ii) optionally a halogenated bisphenol in the presence or absence of catalyst by heating at 80°C to 250°C, the concentration of the epoxy groups being equal to or higher than the concentration of the phenohc groups to prevent the presence of free phenohc groups in the final product.

24. A process for making a flame retardant compound according to claim 1, which comprises reacting epichlorohydrine with i) a halogenated bisphenol and ii) a HBPMAE in the presence of an acid acceptor such as alkali metal hydroxide at a temperature from 25°C to 120°C and then reacting the reaction product in the presence or absence of catalyst at 80°C to 250°C.

25. A process for making a flame retardant compound according to claim 1, which comprises alkylating the phenolic end group of halogenated epoxy resin (D) having an end group of halogenated bisphenol with a free phenol group, the halogenated epoxy resin D being obtained through various processes, for example, by reacting halogenated epoxy resin with excess halogenated bisphenol in the presence or absence of catalyst at a temperature of 80°C-120°C, or a process comprising reacting halogenated bisphenol with epichlorohydrine in the presence of alkali metal hydroxide in such a way that the phenol group concentration is higher than the epoxy group concentration.

26. A process for making a flame retardant compound according to claim 1, which comprises reacting epihydrochlorin with HBPMAE and possibly halogenated bisphenol in the presence of an acid acceptor such as alkali metal hydroxide at a temperature of 25°C-120°C, and then reacting the reaction product with halogenated bisphenols in the presence or absence of catalyst at a temperature of 80°C-250°C.

27. A process according to claim 23, 24 or 26, in the presence of a catalyst wherein the catalyst is selected from alkali metal hydroxides, e.g., sodium hydroxide, tertiary amines, e.g., dimethylbenzylamine, imidazoles, e.g., 2-ethyl-4-methylimidazole, quaternary ammonium salts, e.g., tetramethylammoniumchloride, phosphonium salts, e.g., ethyltriphenylphosphoniumiodide, and phosphines, e.g., triphenylphosphine.

28. A process according to any one of claims 22 to 26 carried out in a solvent which is an organic solvent chosen from among aromatic solvents, ketones or alcohols.