CA2025376A1 - Low gloss flame retardant thermoplastic blends - Google Patents

Low gloss flame retardant thermoplastic blends

Info

Publication number
CA2025376A1
CA2025376A1 CA 2025376 CA2025376A CA2025376A1 CA 2025376 A1 CA2025376 A1 CA 2025376A1 CA 2025376 CA2025376 CA 2025376 CA 2025376 A CA2025376 A CA 2025376A CA 2025376 A1 CA2025376 A1 CA 2025376A1
Authority
CA
Canada
Prior art keywords
composition
styrene
flame retardant
gloss
ring
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Abandoned
Application number
CA 2025376
Other languages
French (fr)
Inventor
James L. Derudder
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
General Electric Co
Original Assignee
General Electric Co
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by General Electric Co filed Critical General Electric Co
Publication of CA2025376A1 publication Critical patent/CA2025376A1/en
Abandoned legal-status Critical Current

Links

Abstract

LOW GLOSS FLAME RETARDANT THERMOPLASTIC BLENDS
Abstract of the Disclosure Low gloss thermoplastic molding blends with reduced gloss and flammability are made by blending polybutylene terephthalate and a gloss reducing, flame retarding amount of an interpolymer of acrylonitrile, butadiene and styrene, at least part of which is ring-brominated styrene.

Description

f `,' 7 `

L~W GLOSS FL~ME RETARDANT THERMOPLASTIC BLENDS
ACKGROUND OF THE INVENTION
Field of the Invention The invention is directed to physical blends of polybutylene terephthalate and an acrylonitrile-butadiene-(brominated styrene) interpolymer useful to mold thermoplastic articles.
Brief Summarv of the Prior Art It has been known that acrylonitrile-butadiene-styrene (hereinafter referred to as "ABS"~ polymers can be physically blended with polyesters such as polybutylene terephthalate (hereinafter called "PBT") to make useful thermoplastic molding compositions, as described for example by Binsack et al. in U.S. Pat.
4,292,233 (Sept. 1981). Improved impact strength of molded articles compared to those molded from PBT alone can be achieved but usually with a perceptible loss of dimensional heat stability, hardness, rigidity and thermooxidative stability.
Moreover, such blends have been associated with molded articles characteristically high in surface gloss. For many important applications, such as machine housings and interior automotive parts, a dull (matte or non-glossy) surface is desirable.
The use of add~tive delustrants (gloss-reducing additives) to achieve low surface gloss is commercially practiced but entails significant disadvantages. The additives are commonly particulate solids, and cause some loss of thermomechanical properties. Certain ABS
varieties can be used as gloss reducing additives but they may lower the heat distortion temperature and they 2 ~ r~

may also induce some PBT polymer degradation and loss of molecular weight during the molding operation as well as in subsequent aging of the molded article.
Furthermore, it is important to have practical means for flame retarding PBT-ABS blends, since, for many commercial applications, a degree of flame retardancy is required; notably in molded electrical parts, business machine housings, and automotive interior parts. The requirement in electrical applications is usually a rating of V-2 in the Underwriters' Laboratory UL-94 test, which requires a specified short flaming time after ignition and allows some dripping. In less demanding applications, such as some small hand-held appliances, an HB rating suffices (limited rate of horizontal burning) and in more demanding applications, a VO rating is needed (short afterflame time, no dripping).
Additives used to obtain flame retardancy, such as polybrominated phenyl ethers, are prone to deposit on molds during processing, and also are prone to bloom to the surface in the finished articles. Certain flame retardant additives such as polybrominated polystyrene avoid the plating out and blooming problems but tend to cause a deficiency in impact strength and sometimes mold corrosion problems because of insufficient thermal stability. All of these phenomena commonlv found with conventional flame retarding additives are undesirable.
I have now found advantageous blends of polybutylene terephthalate (PBT) and a certain specific class of acrylonitrile-butadiene-styrene interpolymers (ABS) which unexpectedly give the desired low surface 0 8 CL o 6 7 9 o 2 ~ 7 gloss without adversely affecting desired strength properties. Advantageous blends of PBT with this specific ABS have been found to have low flammability, without a need for flame retardant additives. Since the flame retardant component of the compositions of our invention is a relatively involatile polymer, it does not bloom or deposit on molds.
Unexpectedly, the compositions of the invention exhibit higher intrinsic viscosities than PBT without affecting physical properties of molded articles. This is advantageous in processing.
SUMMARY OF THE INVENTION
The compositions of the invention, comprise:
(a) polybutylene terephthalate; and (b) a gloss-reducing and flame retardant amount of an interpolymer of acrylonitrile, butadiene, and styrene of which an effective portion is ring-brominated. It is preferred that the ring-brominated styrene be dibrominated styrene.
The compositions of the invention are useful to mold articles such as machine housings and automotive interior parts.
DETAILED DESCRIPTION OF THE INVENTION
The polybutylene terephthalate polymer for use in the compositions of the invention are well known in the art; see for example, U. S. Pat. 4,684,686 (Aug. 1987).
Preferably it is a polyester obtained by polymerizing a glycol component, at least 70 mole %, preferably at least 80 mole %, of which consists of 1,4-butanediol and an acid component at least 70 mole %, preferably at least 80 mole %, of which consists of terephthalic acid, or polyester-forming derivatives thereof.

08CL06790 2~2~i7~

The glycol component may contain not more than 30 mole %, preferably not more than 20 mole %, of another glycol, such as ethylene glycol, trimethylene glycol, 2-methyl-1,3-propanediol, hexamethylene glycol, deca-methylene glycol, cyclohexanedimethanol, neopentyleneglycol or the like.
The acid component may contain not more than 30 mole %, preferably not more than 20 mole %, of another acid such as isophthalic acid, 2,6-naphthalene-dicarboxylic acid, 2,7-naphthalenedicarboxylic acid, 1,5-naphthalenedicarboxylic acid, 4,4'-diphenoxy-ethanedicarboxylic acid, 4,4'-diphenyldicarboxylic acid, p-hydroxybenzoic acid, sebacic acid, adipic acid, or polyester-forming derivatives thereof.
The polybutylene terephthalate used in this invention preferably has an intrinsic viscosity [n]
measured in a 60/40 mixture by weight of phenol/tetrachloroethane at 30 C, of 0.3 to 1.5 dl/g.
The ABS polymer for use as component (b) in the compositions of the invention is, most broadly, any ABS
made using a ring-brominated styrene. ABS itself is well known in the plastics art and is defined, for example, in the Modern Plastics Encyclopedia, 1989 edition, page 92, as the family of thermoplastics made from the three monomers acrylonitrile, butadiene and styrene, and includes a mixture (alloy) of styrene-acrylonitrile copolymer with SAN-grafted polybutadiene rubber. The use of a ring-brominated styrene in preparing ABS is described for example by Arthur et al.
in Canadian Patent 1 149 984 (issued July 12, 1983), as well as by Ikeda et al. in Japanese Patent 1987-10689 published Jan. 31, 1978.

The preferred ABS polymer made from a ring-brominated styrene is that made using dibromostyrene as a monomer, this polymer having a particularly good balance of physical properties, stability and cost.
The ring-brominated styrenes used to make the ABS
interpolymers for use in the invention are themselves well known in the art, and include the various ring position isomers of mono-, di-, tri-, tetra- and pentabromostyrene. Any isomer or mixture of isomers is usable. For reasons of cost, stability, polymeriz-ability, and availability, the di- and tribrominated styrenes are preferred and the dibrominated styrenes most preferred.
The ABS made utilizing ring-brominated styrene may be made using all ring-brominated styrene and no unbrominated styrene, but it is preferred that some unbrominated styrene be used. The ABS should have at least 10% content of brominated styrene and preferably at least 20%, relative to total ABS (by weight).
A gloss reducing and flame retarding proportion of the ABS employed herein is generally in the range of from about 10% to about 70% by weight of the total blend of (a) and (b). A preferred range of component (b) is 20% to 60%. It will be appreciated that if another gloss reducing component is added, such as silica or other delustrant, or another flame retardant, somewhat lesser amounts of (b) can suffice, whereas if very low surface gloss is required, somewhat greater amounts of (b) can be used.
The compositions of the invention may be modified by the addition of other types of additives conven-tionally used in the art of plastics compounding.

2~2 Such additives can include fillers (such as clay or talc), supplementary delustrants, reinforcing agents (such as glass fibers), impact modifiers, antistats, plasticizers, flow promoters and other processing aids, stabilizers, colorants, mold release agents, supplementary or synergistic flame retardants, ultraviolet screening agents, drip inhibitors such as polytetrafluoroethylene (PTFE) and the like; see for example U.S. Patents 3,005,795: 3,671,487 and 4,463,130. It is advantageous to use a drip-retarding amount of fibrilar polytetrafluoroethylene. This is added as a concentrate at the rate of about 0.02 to 2%
by weight and has a favorable effect in retarding the occurrence of flaming drips in combustion of the polymer component of the compositions of the invention.
A preferred optional ingredient is a synergistic flame retardant amount of antimony oxide, since by this means, Underwriters Laboratory UL-94 flammability test ratings can be further improved. The synergistic amount can be from about 1% to about 15% and preferably from about 2% to about 8% of the total resin blend. As will be obvious to one skilled in the art of flame retardant formulation, the higher the bromine content of the resin, the less antimony oxide is needed and vice versa.
The production of the compositions of the invention is done by any of the blending operations known for the blending of thermoplastics, such as blending in a kneading machine such as a Banbury mixer or an extruder, or solvent blending. The sequence of addition is not critical but all components should be thoroughly blended together. Blending can be done continuously or 08CL06790 ~'~ ?~3~ 7~

batchwise. A preferred blending method is melt blending with the use of an extruder, such as a twin screw extruder.
The invention will be better understood with reference to the following examples, which are presented for purposes of`illustration rather than for limitation, and which set forth the best mode contemplated for carrying out the invention.

Molding compositions were prepared by melt blending the ingredients indicated in the Table below in a twin screw extruder at a temperature of 220-270 C and at 100-200 rpm. The blended and extruded material was then pelletized, dried and injection molded at about 240 C
to prepare test specimens. The gloss was measured by ASTM Test Method D-1003 at 60 using a Gardner gloss meter. Other physical properties were measured on injection molded samples using the following ASTM test methods: Tensile properties, D638; impact by notched Izod, D2S6; heat deflection temperature (DTUL), D648-56; flexural properties, D790. Flammability was tested by the UL-94 method of Underwriters' Laboratory. The Kasha index is a method for determining melt viscosity, more fully described in column 5 of U. S. Pat.
4,735,978 incorporated herein by reference thereto.
The formulations and results are as follows:

.

?.~ ~ ?. ~

TABLE
Example No.: 1 2 3 4 Composition (wt.%):
DABSl 20 40 60 20 PBT2 79.0558.5538.05 80 PTFE3 0.3 0.3 0-3 1.0 Stabilizers 0.65 1.15 1.65 0.7 Flame Retardant4 - - - 0.6 Properties:
10 N/Izod ftlb/in 1/8" 0.82 0.3 0.75 0.8 3.175mm " J/m 44 43 40 43 UN/Izod ftlb/in 17.6 13.1 16.1 31.3 " " J/m 940 700 860 1670 Gloss 60 88 85.5 88.5 71 15 Tensile yield lb/in2 - 7600 7200 " " MPa - 52 50 Tensile break lb/in2 - 5100 5000 " " MPa - 35 34 Elongation% at break - 12 11 20 Flex. strength psi - 11800 11100 " " MPa - 81.4 76.6 Flex. modulus Kpsi - 348 344 " MPa - 2400 2370 DTUL @ 264 psi (1.82 MPa) C - 191 178 180 25 Kasha Index 6 min. 0 250C 5720 9420 18140 7860 " " of molded part 3600 6650 11860 5150 " " 12 min. @ 250C 4820 9710 19960 % change KI pellet to part37.1 29.4 34.6 34.5 % change KI 6 to 12 min. 15.7 -3.1 -10.0 30 UL-94 rating HB HB HB HB

08CL06790 2~2~7~

Notes to table:
l. Blendex ~ 226, a bromine containing ABS made by General Electric Co. using 27% dibromostyrene, 16.7%
acrylonitrile, 21% butadiene, and 35.5% styrene.
2. Valox ~ 315 made by General Electric Co.
3. Fibrillar polytetrafluoroethylene (in an 80 percent polycarbonate concentrate). The PTFE concentrate is made with a mixture of polycarbonate (Lexan ~
145) and tetrabromobisphenol A polycarbonate in a 1:1 ratio followed by drying so that the PTFE
concentration is 20% by weight.
4. Potassium salt of diphenylsulfone sulfonate (KSS).
The Table shows the substantial lowering of surface gloss by inclusion of the specified ABS in the biend;
for comparison, the gloss of PBT without DABS is >lon.
The Table also shows the unexpected increase in heat distortion temperature (DTUL), as well as the good thermal stability (as shown by retention; and in one case rise of Kasha Index) while the sample is being heated at 300C. for 6 to 12 minutes. The Table also shows the reduced flammability rating (HB) obtained in the UL-94 test of compositions of the invention.

Claims (9)

1. A thermoplastic molding composition which consists essentially of;
(a) polybutylene terephthalate; and (b) an effective gloss reducing amount of an interpolymer of acrylonitrile, butadiene, and styrene, an effective portion of which is ring-brominated styrene.
2. The composition of claim 1, wherein the effective amount is within the range of from about 10 to about 70 weight percent of the composition and the effective portion is at least 10% by weight of the ABS.
3. A composition of claim 2 wherein said interpolymer has a ring-brominated styrene content of at least 20%.
4. A composition of claim 2 wherein said ring-brominated styrene is dibromostyrene.
5. A composition of claim 2 wherein the effective amount is within the range of from 20 to 60 percent.
6. A composition of claim l which further contains a synergistic flame retardant amount of antimony oxide.
7. A composition of claim 1 which further contains polytetrafluoroethylene drip inhibitor.
8. An article molded from the composition of claim l.
9. The invention as defined in any of the preceding claims including any further features of novelty disclosed.
CA 2025376 1989-11-16 1990-09-14 Low gloss flame retardant thermoplastic blends Abandoned CA2025376A1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US43747589A 1989-11-16 1989-11-16
US437,475 1989-11-16

Publications (1)

Publication Number Publication Date
CA2025376A1 true CA2025376A1 (en) 1991-05-17

Family

ID=23736609

Family Applications (1)

Application Number Title Priority Date Filing Date
CA 2025376 Abandoned CA2025376A1 (en) 1989-11-16 1990-09-14 Low gloss flame retardant thermoplastic blends

Country Status (1)

Country Link
CA (1) CA2025376A1 (en)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0483510A2 (en) * 1990-10-31 1992-05-06 General Electric Company Polycarbonate compositions with improved appearance and flammability characteristics
US8222351B2 (en) 2007-02-12 2012-07-17 Sabic Innovative Plastics Ip B.V. Low gloss polycarbonate compositions
US8222350B2 (en) 2007-02-12 2012-07-17 Sabic Innovative Plastics Ip B.V. Low gloss polycarbonate compositions

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0483510A2 (en) * 1990-10-31 1992-05-06 General Electric Company Polycarbonate compositions with improved appearance and flammability characteristics
EP0483510A3 (en) * 1990-10-31 1992-09-02 General Electric Company Polycarbonate compositions with improved appearance and flammability characteristics
US8222351B2 (en) 2007-02-12 2012-07-17 Sabic Innovative Plastics Ip B.V. Low gloss polycarbonate compositions
US8222350B2 (en) 2007-02-12 2012-07-17 Sabic Innovative Plastics Ip B.V. Low gloss polycarbonate compositions

Similar Documents

Publication Publication Date Title
EP0363608B1 (en) Polymer mixture comprising an aromatic polycarbonate, a styrene-containing copolymer and/or graft polymer and a phosphate based flame-retardant; articles formed therefrom
US5254610A (en) Polyester/polycarbonate blends containing phosphites
US4035333A (en) Flame-resistant resin composition
EP0728811B1 (en) Flame retardant thermoplastic resin composition
US4284549A (en) Polymer blends with improved hydrolytic stability
JP3961046B2 (en) Phosphate flame retardant polymer
EP0270366A2 (en) Novel flame retardant
JPH04227954A (en) Fire-retardant blend of polycarbonate, abs and terpolymer
JPH04363357A (en) Thermoplastic resin composition excellent in weather resistance
US6187848B1 (en) Glass filled polyester compositions with improved color stability
CA1104734A (en) Unfilled thermoplastic molding compositions
CA2025376A1 (en) Low gloss flame retardant thermoplastic blends
JPS6366261A (en) Fire-retardant compound and thermoplastic composition containing the same
EP0020707B1 (en) Modified polyester compositions
KR20020006350A (en) Composition of aromatic polycarbonate resin having superior flame retardant
JPH0471101B2 (en)
JPH0127102B2 (en)
JP2003165911A (en) Flame retardant thermoplastic resin composition
EP0453524A4 (en) Aromatic triester plasticized copolymers of acrylonitrile and styrene
JPH01266159A (en) Antistatic thermoplastic resin composition
KR100245949B1 (en) Thermoplastic resin composition
JP3122550B2 (en) Resin composition
JP2793350B2 (en) Flame retardant styrenic resin composition
EP0042737A1 (en) Polyethylene terephthalate blends
EP0379255A2 (en) Thermoplastic resin composition

Legal Events

Date Code Title Description
FZDE Dead