IL107385A - Low-bromine content flame retarded high-impact abs compositions - Google Patents

Description

REF : 2935/93 i2 o D»¾N ABS 0">OI by> mj>_. Osiyn ϋ*η*ΐ-θη -BROMINE CONTENT FLAME RETARDED HIGH- IMPACT ABS COMPOSITIONS 2935/93 -1- LOW-BROMINE CONTENT FLAME RETARDED HIGH-IMPACT ABS COMPOSITIONS Field of the Invention The present invention relates to flame-retarded plastic compositions having high bromine efficiency. More particularly, the invention relates to low-bromine high-impact acrylonitryle-butadiene-styrene resins, containing brominated epoxy flame-retardant compounds.

Background of the Invention The application of plastics in various electrical and/or electronics appliances such as TV cabinets, TV racks, business machine housings, electrical boxes, connectors, etc., demands of these plastics a high level of flame retardancy. Usually, this high, level of flame retardancy is expressed in UL-94 V rating for: 1.6 mm and even 0.8 mm thickness. Such flame retardancy is usually achieved by an addition of bromine and/or chlorine-containing compounds, often in combination with synergists such as antimony trioxide, zinc borates, molybdenum, or bismuth compounds, compounds containing nitrogen and/or phosphorous, inorganic fillers, etc.

The choice of flame retardant is based usually on economic, toxicological reasons, and on the particular properties of flame -retarded plastics. All such characteristics are dependent on the so-called bromine efficiency of flame retardants, i.e. on the value of minimal bromine content, which provides the desired level of flame retardancy. 2935/93 -2- The Prior Art Flame retardants based on tetrabromobis-phenol A (TBBA) present a good combination of the above-mentioned properties. TBBA itself is relatively inexpensive, does not present "dioxin danger", and permits to produce flame-retarded (FR) plastics with acceptable properties at a relatively high level of bromine efficiency [J. Thies, "Tetrabromobisphenol A (TBBA), its derivatives and their flame-retarded (FR) polymers - content of polybrominated dibenzo-p-dioxins (PBDD)", Chemosphere, vol. 20, p. 1921 (1990)].

The main disadvantage of TBBA is its relatively low level of processing heat stability, which limits its application, especially in engineering plastics, and the relatively low level of light stability of plastics flame-retarded with TBBA. The disadvantage may be overcome to some extent by the proper selection of heat- and UV-stabilizers [JP 61185565, JP 4023847, DE 4015844, JP 04268354].

Another way is to use TBBA derivatives, such as TBBA-based epoxy and TBBA-based polycarbonates. These polymeric and oligomeric derivatives of TBBA combine the advantages of TBBA with higher heat- and UV-stability.

TBBA-based epoxy FRs are widely used as flame retardants for various plastics [JP 0118243, JP 0218437, JP 03199251, JP 051255238, JP 05148391, JP 03163157, JP 03170546, JP 03227359, EP 421307, EP 0100582], 2935/93 -3- Among TBBA-based epoxy FRs, the F-2000 series is a group of flame retardants providing a great variety of properties and possibilities of application in plastics. These compounds have the general formula: where n=0 - 200. The average molecular weight of such compounds is comprised between 700 and 120,000.

SUMMARY OF THE INVENTION It has now most surprisingly been found, and this is an object of the invention, that using a bromine-containing epoxy flame-retardant compound as the flame-retardant for High-Impact Acrylonitrile- Butadiene-Styrene (HABS) permits to lower the total bromine content, and to r educe the amount of FR required to achieve good flame - retardancy. 2935/93 -4- It is an object of the invention to provide flame-retarded plastic compositions based on HABS, containing reduce amounts of bromine.

It is another object of the invention to provide such compositions which comprise, in addition to the bromine-containing epoxy flame-retardant compound, also additional and/or synergistic FR compounds.

Other objects of the invention will become apparent as the description proceeds.

The flame-retarded plastic composition of the invention comprises High-Impact Acrylonitrile-Butadiene-Styrene resin (HABS) and a bromine-containing epoxy flame-retardant compound, alone or together with other flame retardant or flame-retardant synergistic compounds.

According to a preferred embodiment of the invention, the bromine-containing epoxy flame-retardant compound is a compound selected from the F-2000 family defined above. More preferably (but not hmitatively), the average molecular weight of the said compound is between 1,200 and 80,000.

Preferably, but not limitatively, the amount of FR is between about 10% and about 26% by weight of the total composition.

According to a preferred embodiment of the invention the flame-retardant synergist is antimony trioxide. Antimony trioxide can be present in varying amounts, but its content is typically between about 1% and about 12% by weight of the total composition. 2935/93 -5- According to the invention it is possible to produce HABS plastic compositions which are UL94 V-0 rated (1.6 mm), and wherein the total amount of bromine is 14% or less. This, as will be appreciated by the skilled person, is very advantageous, and is also most surprising, since usually bromine efficiency is worse in HABS than in general purpose ABS, which is widely used in conjunction with FR compounds. HABS, as will be appreciated by the skilled persons, is ABS modified by the addition of a rubber, for the purposes of obtaining improved values for the impact of the final product.

Thus, in its broad sense, the invention is directed to the use of brom mated epoxy flame-retardant compounds for the preparation of low bromine-content, flame-retarded High-Impact Acrylonitrile-Butadiene-Styrene resins. Preferred bromine- containing epoxy to be used in the compositions of the invention are those having a range of molecular weight from 1200 to 80, 000; While, as stated, the invention is specifically advantageous where HABS is concerned, it can be used to produce FR-plastic composition with high bromine efficiency, comprising other plastic materials together with HABS. Examples of such other plastic materials are, e.g., high-impact polystyrene (HIPS), polystyrene, poly-a -methylstyrene, styrene acrylonitrile copolymer (SAN), styrene-maleic anhydride copolymer (SMA), or thermoplastic compositions selected from the blends of the above-mentioned polymers with other polymers such as polycarbonate (PC), polyphenylene oxide (PPO), polyphenylene sulfide (PPS), polyvinyl chloride (PVC), chlorinated polyvinyl chloride (CPVC), chlorinated 2935/93 -6- polyethylene (CPE), thermoplastic elastomers (such as styrene-butadiene rubber (SBR), styrene-butadiene-styrene, hydrogenated copolymers of styrene-butadiene, ethylene-propylenediene terpolymer (EPDM), polyurethanes, etc.

Of course, the composition of the invention may further comprise conventional plastic additives, such as heat- and UV-stabilizers, lubricants, processing aids, halogen hydride scavengers, inorganic fillers, etc.

The compositions of the invention may be prepared in processing equipment such as single or twin screw extruders, co-kneader or other kind of compounding apparatus. The process of compounding may be a one- or two-step process. The latter includes as a first step the compounding of a concentrate or master batch containing flame retardant, synergist, tougheners, and other necessary additives.

All the above and other characteristics and advantages of the invention will be better understood through the following illustrative description of preferred embodiments. The examples given below are provided by way of illustration and are not intended to limit the invention.

Example 1 (Comparative) Various compositions of flame-retarded ABS were prepared on the basis of general purpose ABS NOVODUR P2 HAT ex Bayer, as specified in Table I. Compounding was done in the laboratory with a twin screw extruder (ex Brabender) at 140-200°C, with water cooling and pelletizing. 2935/93 -7- The pellets produced were dried and then subjected to injection-molding in an Arburg All-rounder 221-75-350 injection molding machine, at 160-230°C. Molded specimens were tested as follows: - UL-94 vertical burning test according to Underwriter Laboratories, Inc. "Tests for flammability of plastic materials for parts in devices and appliances", 4th edition, 1991; - Izod impact test according to ASTM D-256-92; - heat deflection temperature test (HDT) according to ASTM D 648-72 with a load of 1820 kPa.

Table I illustrates the Br-efficiency of bromine-containing epoxy F-2016, which is an F-2000 compound (as defined above) having an average molecular weight of 1,600, in comparison with such widely used commercial FRs as octabromodiphenyl oxide (FR-1208, ex DSBG, Israel) and bis(tribromophenoxy)ethane (FF-680, ex GLCC, U.S.A.). 2935/93 -8- TABLE I Bromine efficiency of various FRs in general purpose ABS . *octabromodiphenyl oxide ** TBBA-based epoxy Example 2 Various compositions of flame-retarded ABS were prepared on the basis of high impact ABS NOVODUR P 2K ex Bayer, Germany, as specified in Table II.

The compounding was done in laboratory twin screw extruder ex Brabender at 140-200°C with water cooling and pelletizing. The pellets 2935/93 -9- produced were dried and then subjected to injection-molding in an Arburg All-rounder 221-75-350 injection molding machine at 160-230°C. Molded specimens were tested as follows:, - UL-94 vertical burning test according to Underwriter Laboratories, Inc. "Tests for flam m ability of plastic materials for parts in devices and appliances", 4th edition, 1991; - Izod impact test according to ASTM D-256-92; - heat deflection temperature test (HDT) according to ASTM D 648- 72 with the load 1820 kPa; - color evaluation through an evaluation of difference between tested specimen and white reference (DE).

Color evaluation has been done for molded specimens and for the same specimens after 250 hours of exposure to UV-irradiation by B-lamps in Q.U.V. weatherometer. 2935/93 -10- TABLE II Bromine efficiency of various FRs in high impact ABS FORMULATIONS Table II illustrates very high efficiency of bromine-containing epoxy F- 2016 in HABS, in comparison with such commercial FRs as octabromodiphenyl oxide (FR-1208) and tetrabromobisphenol A (FR-1524) and bis(tribromophenoxy)ethane (FF-680). It is noted, referring to Example 1, that the similar or better efficiency of F-2016 with HABS, as compared with general purpose ABS, is remarkable. 2935/93 -11- All the above description and examples have been given for the purpose of illustration and are not intended to limit the invention in any way. many different compositions, containing many different bromine-containing epoxy compounds can be prepared, without exceeding the scope of the invention.

Claims (12)

CLAIMS:

1. A flame-retarded plastic composition comprising High-Impact Acrylonitrile-Butadiene-Styrene resin (HABS) and a bromine- containing epoxy flame-retardant compound, alone or together with other flame retardant or flame-retardant synergistic compounds.

2. A composition according to claim 1, wherein the bromine-containing epoxy flame-retardant compound is a compound of the formula: wherein n = 0 - 200.

3. A composition according to claim 2, wherein the bromine-containing epoxy flame-retardant compound has a mean molecular weight comprised between 700 and 120,000, preferably between 1,200 and 80,000. 2935/93 -13-

4. A composition according to any one of claims 1 to 3, wherein the amount of FR is between about 10% and about 26% by weight of the total composition.

5. A compositions according to claim 1, wherein the flame-retardant synergist is antimony trioxide.

6. A composition according to claim 5, wherein the amount of antimony trioxide is between about 1% and about 12% by weight of the total composition.

7. A composition according to claim 1, which is UL94 VO-rated, wherein the total amount of bromine is 14% or less.

8. A composition according to any one of claims 1 to 7, which comprises, in addition to HABS, one or more additional plastic materials.

9. A composition according to claim 8, wherein the plastic material is selected from the group consisting essentially of high-impact polystyrene (HIPS), polystyrene, poly-a-methylstyrene, styrene acrylonitrile copolymer (SAN), styrene-maleic anhydride copolymer (SMA), or thermoplastic compositions selected from the blends of the above-mentioned polymers with other polymers such as polycarbonate (PC), polyphenylene oxide (PPO), polyphenylene sulfide (PPS), polyvinyl chloride (PVC), chlorinated polyvinyl chloride (CPVC), chlorinated polyethylene (CPE), thermoplastic elastomers (such as styrene-butadiene rubber (SBR), styrene-butadiene -styrene, hydrogenated copolymers of styrene-butadiene, ethylene-propylenediene terpolymer (EPDM), and polyurethanes. 2935/93 -14-

10. A composition according to any one of claims 1 to 9, further comprising conventional plastic additives.

11. A composition according to claim 10, wherein the conventional plastic additives comprise one or more of heat- and UV- stabilizers, lubricants, processing aids, halogen hydride scavengers and inorganic fillers.

12. Use of brominated epoxy flame-retardant compounds for the preparation of low bromine-content, flame-retarded High-Impact Acrylonitrile-Butadiene-Styrene resins. WHXft JIN wxxft