Classifications

• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
  • C08K5/00—Use of organic ingredients
  • C08K5/0008—Organic ingredients according to more than one of the "one dot" groups of C08K5/01 - C08K5/59
  • C08K5/005—Stabilisers against oxidation, heat, light, ozone
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
  • C08K5/00—Use of organic ingredients
  • C08K5/0008—Organic ingredients according to more than one of the "one dot" groups of C08K5/01 - C08K5/59
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
  • C08K5/00—Use of organic ingredients
  • C08K5/49—Phosphorus-containing compounds
  • C08K5/51—Phosphorus bound to oxygen
  • C08K5/52—Phosphorus bound to oxygen only
  • C08K5/521—Esters of phosphoric acids, e.g. of H3PO4
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • C08L23/00—Compositions of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Compositions of derivatives of such polymers
  • C08L23/02—Compositions of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Compositions of derivatives of such polymers not modified by chemical after-treatment
  • C08L23/10—Homopolymers or copolymers of propene
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • C08L23/00—Compositions of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Compositions of derivatives of such polymers
  • C08L23/02—Compositions of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Compositions of derivatives of such polymers not modified by chemical after-treatment
  • C08L23/04—Homopolymers or copolymers of ethene
  • C08L23/08—Copolymers of ethene
  • C08L23/0807—Copolymers of ethene with unsaturated hydrocarbons only containing more than three carbon atoms
  • C08L23/0815—Copolymers of ethene with aliphatic 1-olefins

Definitions

• This invention relates to flame resistant polyolefin compositions. More particularly, this invention relates to flame resistant polyolefin compositions that resist blooming, and to methods for improving the bloom resistance of flame resistant polyolefins.
• the UL (Underwriters Laboratory) 94 test is commonly used to measure the flame retardancy of a polymer.
• a test specimen of polymer (either 5" x 1/8" or 5" x 1/16") is exposed vertically to the flame from a Bunsen burner for 10 seconds. The specimen is ignited at the bottom and burns up. If the specimen self-extinguishes within 30 seconds, a second 20 second application of the flame is made. Flaming droplets are allowed to fall on dry absorbent surgical cotton located 12 inches below the sample. If the average burn time is less than 5 seconds and the drips do not ignite the cotton, the polymer is classified as V-0 in the UL94 test.
• the polymer is classified as V-l. If the sample is self- extinguishing but the cotton is ignited, the material is classified as V-2.
• Polyolefins such as polypropylene and copolymers of propylene and ethylene are useful in a variety of applications. In many of these applications it is preferred or mandatory to incorporate an additive into the polyolefin to improve its flame resistance or retardance. Although addition of flame retardants improves the flame retardant properties of polyolefins, the addition of the flame retardant, particularly in amounts necessary to provide a V-0 rated composition in the UL94 test, detracts significantly from the physical properties of the polyolefin. Thus, the use of flame retardants is usually a compromise between the desire for a particular degree of flame retardancy and the need to detract as little as possible from the desirable properties of the polyolefin.
• a V-0 rated polypropylene can be produced by incorporating flame retardants, these additives bloom from the polymer. Blooming, or plating out, is the separation of the additive from the polyolefin matrix as evidenced by a surface film on a molded specimen of polyolefin that contains the additive. Blooming may occur during cooling of the article in the mold, or may be induced via heat aging at elevated temperatures and/or extended times. The blooming problem is particularly pronounced and difficult to overcome at relatively high heat aging temperatures, that is at heat aging temperatures above approximately 70°C.
• Blooming is believed to be due to the fact that the additive is more polar than the polymer to which it has been added. Thus, blooming is a function of both the additive and the polymer to which it is added. Blooming of polar additives is an especially severe problem in polypropylene, a highly non-polar polymer.
• Blooming of the flame retardant not only mars the appearance of the final product but may also reduce the flame resistant properties of the polymer over time due to loss of the flame retardant.
• Many electrical applications for flame retardant polymers require RTI (Relative Thermal Index) ratings that involve 18 months heat aging without a loss of physical properties and flame retardant performance. If the additive blooms from the polymer, the polymer can not achieve the required RTI rating.
• Tris- (trihaloneopentyl) phosphates especially tr ⁇ s-
• the invention is a flame and bloom resistant composition
• a flame and bloom resistant composition comprising: (a) at least one polyolefin; (b) a flame retarding amount of at least one polar flame retardant; and (c) a bloom inhibiting amount of at least one elastomer; wherein: the elastomer is compatible with the polyolefin; and the amount of elastomer added does not exceed 20 parts by weight of elastomer per 100 parts by weight of polyolefin.
• a Preferred polyolefins are polypropylene, propylene/ethylene copolymers, and mixtures and blends thereof.
• Preferred elastomers are ⁇ -octene/ethylene elastomers.
• a preferred polar flame retardant is tris-
• composition resists blooming even at high heat aging temperatures. It is preferred that the total amount of polar flame retardants added does not exceed about 15 parts by weight of polar flame retardant or flame retardants per 100 parts by weight of polyolefin.
• the invention is a method for improving the bloom resistance of flame resistant compositions, the method comprising adding at least one polar flame retardant and at least one elastomer to a polyolefin.
• the preferred elastomers are substantially linear ethylene/C 3 -C 2 o ⁇ -olefin copolymers, especially substantially linear ethylene/C 5 -C 10 ⁇ -olefin copolymers, prepared by constrained geometry catalysis using metallocene catalysts. These copolymers are disclosed in McKay, U.S. Patent No. 5,747,580, and Chum, U.S. Patent 5,677,383, incorporated herein by reference. These copolymers are sometimes known as "metallocene elastomers. "
• More preferred elastomers are substantially linear ⁇ -octene/ethylene copolymers available as the Engage ® polyolefin elastomers from DuPont Dow Elastomers, Wilmington, DE. These materials have: densities of about 0.863 g/cm 3 to about 0.913 g/cm 3 ; melt flow indices of about 0.5 dg/min to about 30 dg/min; differential thermal analysis melting peaks of about 49°C to about 107°C; ultimate tensile strengths of about 4.1 MPa to about 33.8 MPa; and ultimate elongations of about 700% to greater than 1000%.
• the amount of elastomer used should be sufficient to yield an improvement in the bloom resistance of the polymer. Typically, such amounts are about 2 to 5 parts by weight of the elastomer per 100 parts by weight of polyolefin. However, up to about 20 parts by weight of elastomer, preferably up to 15 parts by weight of elastomer, may be added to reduce blooming under severe conditions, such as heating at 100°C for seven days.
• any particular elastomer may vary depending upon the polyolefin and flame retardant or retardants selected. In addition, the selection of a specific elastomer will also depend upon the particular application specifications. Elastomers having the requisite properties for optimization of bloom inhibition and good physical performance may be selected by routine testing.
• the polyolefins may be derived from a variety of monomers especially propylene, ethylene, butene, iso- butylene, pentene, hexene, heptene, octene, 2 -methyl propene, 2-methyl butene, 4-methylpentene, 4-methyl hexene, 5-methylhexene, bicyclo- (2, 2, 1) -2-heptene, butadiene, pentadiene, hexadiene, isoprene, 2, 3 -dimethyl butadiene, 3,1-methyl pentadiene, 1,3,4- vinylcyclohexene, vinylcyclohexene, cyclopentadiene, styrene and methyl styrene.
• the polyolefins include copolymers produced from two or more of any of the foregoing monomers and the like, and further include homopolymer blend
• the preferred polyolefins are polypropylene and polyethylene, including atactic, syndiotactic and isotactic polypropylene and polyethylene, low density polyethylene, high density polyethylene, linear low density polyethylene, block copolymers of ethylene and propylene, and random copolymers of ethylene and propylene.
• Polypropylene, propylene/ethylene copolymers, and mixtures and blends thereof are more preferred. With respect to these polymers and copolymers, the term "mixtures" includes blends.
• polystyrene resins may be produced using a variety of catalytic processes.
• the polyolefins useful in this invention may be produced by any of these processes including metallocene catalyzed processes.
• the polymers may have a range of melt indexes (MI) but will typically have MI values in the range 4 to 30.
• the flame retardants may be any polar flame retardant additives described in the literature. A useful review of flame retardants is included in Thermoplastic Polymer Additives - Theory and Practice.
• a polar additive is an additive that is polar relative to the polyolefin.
• a polar flame retardant is a flame retardant that is polar relative to the polyolefin.
• the term polar additive includes polar flame retardants as well as other polar additives, such as polar photostabilizers, polar thermal stabilizers, polar pigments, etc.
• Polar flame retardant does not refer to the various flame retardant synergists for halogenated flame retardants, such as antimony trioxide and zinc borate .
• polar flame retardants which may be useful are decabromodiphenyl oxide, available from Great Lakes Chemicals under the designation Decabrom; tetrabromo is-phenol-A--bis- (2, 3-dibromopropyl ether), available from Great Lakes Chemical Corporation under the designation PE-68; tetrabromo Jbis-phenol-S-jbis- (2 , 3- dibromopropyl ether) , available as under the designation Non-Nen-52 from Manac Inc. of Japan; adducts of hexachloroentadiene and cyclooctadiene, such as Dechlorane Plus available from Oxychem; ethylene bis-
• polar flame retardant or flame retardants typically does not exceed about 15 parts by weight of polar flame retardant or flame retardants per 100 parts by weight of polyolefin.
• polar flame retardants include tris- (trihalo- neopentyl) phosphates, aromatic and aliphatic halogenated phosphate esters, and other halogenated phosphates, and combinations thereof.
• Preferred tris- (trihaloneopentyl) phosphates are tris- (trichloroneopentyl) phosphate, tris- (chlorodibromo- neopentyl) phosphate, tris- (dichlorobromoneopentyl) - phosphate, tris- (tribromoneopentyl) phosphate, and combinations thereof.
• tris- (trihaloneopentyl) phosphate is tris- (tribromoneopentyl) phosphate [tris- (3-bromo-2, 2-bis (bromomethyl) propyl) phosphate] .
• synergists for halogenated flame retardants may be used.
• Useful synergists include antimony trioxide, sodium antimonate, antimony pentoxide, zinc stannate, zinc hydroxystannate, zinc borate, and any mixtures of two or more thereof.
• Preferred synergists are antimony trioxide and zinc borate .
• Zinc borate can be used to substitute for 40 to 60% of an antimony containing synergist on a weight basis. This produces a lighter product due to the specific gravity difference between zinc borate and the antimony containing synergist.
• Zinc borate is commercially available under the designation Firebrake ® 415.
• compositions may also comprise various other additives, such as photostabilzers, thermal stabilizers, antistatic and nucleating agents, pigments, fillers, glass, and other materials known in the art.
• Photostabilizers and thermal stabilizers include, for example, those available from Ciba-Geigy under the designations Irganox ® and Tinuvin ® .
• the amount of polar flame retardants used should be an amount effective to yield the desired flame resistance of the polymer. Amounts will vary depending upon the particular flame retardants and polyolefin used and on the UL94 rating desired. The combination of additives may optimized using routine experimentation to achieve the particular goals desired. The nature of the polymer, the degree of flame retardancy required, the cost of the polymer, the costs of the various additives, the intended use for the flame retardant polymer, and the value in use of the flame retardant polymer are all factors that may influence the combination of additives selected.
• a preferred combination of additives for use in polyolefins, especially in polypropylene, propylene/- ethylene copolymers, and mixtures and blends thereof, is disclosed in Papazoglou, WO 98/17718, incorporated herein by reference.
• the composition comprises: the polyolefin, preferably polypropylene; 3 to 10% by weight of at least one tris- (trihaloneopentyl) phosphate flame retardant, preferably tris- (tribromoneopentyl) phosphate; 0.5 to 5% of a co-additive halogenated flame retardant having at least one halogen atom attached to an aliphatic carbon atom as part of its molecular structure, preferably tetrabromobisphenol-A-bis (2, 3- dibromopropyl) ether or tetrabromobisphenol-S-bis (2, 3- dibromopropyl) ether; and a flame retardant synergist selected from the group consisting of antimony trioxide, antimony pentoxide, zinc stannate, sodium antimonate, zinc hydroxystannate, and zinc borate, preferably antimony trioxide in which the ratio of the weight of antimony trioxide to the total weight of the tris (trihalone
• compositions may be compounded using techniques well known in the art. It is desirable to achieve uniformity of the formulation if the optimum flame retardant and bloom resistant performance is to be obtained.
• the use of a twin screw extruder is preferred to the use of a single screw extruder.
• a suitable masterbatch typically comprises the polyolefin and from 5 to 20% (preferably from 10 to 20%) of the halogenated flame retardant.
• compositions of the invention also comprise a polyolefin, a bloom inhibiting amount of elastomer and a relatively low molecular weight additive that is polar relative to the polyolefin.
• Methods of the invention comprise a method for improving the bloom resistance of a polyolefin composition comprising also providing in the composition at least one elastomer.
• compositions of this invention are especially useful for articles fabricated by molding processes, particularly for molded products used in the electrical industry.
• the advantageous properties of this invention can be observed by reference to the following examples which illustrate, but do not limit, the invention.
• DLPDP Dilauryl thio dipropionate Engage ® 8180 Elastomer (density, 0.863 g/cm ; Mooney viscosity at 121°C, 35; melt flow index, 30 dg/min; shore hardness, 66; DSC melting peak, 49°C; ultimate elongation, >800%) (DuPont Dow, Wilmington, DE)
• Engage ® 8403 Elastomer (density, 0.913 g/cm ; Mooney viscosity at 121°C, 1.5; melt flow index, 0.5 dg/min; shore hardness, 96; DSC melting peak, 107°C; ultimate elongation, 700%) (DuPont Dow, Wilmington, DE)
• Irganox ⁇ 1010 Tetrakis [methylene (3 , 5-di- t-butyl-4 - hydroxyhydrocinnamate] methane (Ciba- Geigy)
• Non-Nen-52 Tetrabromo-jbis-phenol-S-Jis- (2,3) - dibromopropyl ether (Manac)
• PE-68 Tetrabromo- is-phenol-A-Jbis- (2,3) - dibromopropyl ether (Great Lakes Chemical)
• the extruded strands were quenched in a 6 ' water bath and then pelletized.
• the pellets were air dried overnight to remove surface moisture, and subsequently injection molded in a Battenfeld 800/315CDC injection molding machine, operating at the following conditions:
• the mold used was a simple cavity mold producing a square plaque (2" x 2" x 1/8"), two 1/8" UL bars (1/2" x 5" x 1/8"), one 1/16" UL bar (1/2" x 5" x 1/16"), one 3/16" UL bar (1/2" x 5" x 3/16"), one ASTM tensile specimen (3/4" x 6" x 1/8"), one ASTM Izod specimen (1/2" x 2" x 1/8"), and one Oxygen Index specimen (1/4" x 5" x 1/8") .
• Molded plaques of the desired formulations were (2" x 2" x 1/8") were oven aged at 100°C in a recirculating oven for either 8 days or 28 days. The plaques were then placed into a 400 mL beaker containing approximately 50 mL of dichloromethane for 3 min with continuous stirring. The solvent was transferred into a pre-weighed cup and allowed to evaporate. The residue was assumed to be bloomed flame retardant material .
• Oxygen index is defined as the minimum concentration of oxygen, expressed in volume percent, that will just support combustion. Oxygen index measurements were made following ASTM D-2863 as described in Papazoglou, WO 98/17718, . UL94 measurements were carried out using standard procedures.
• Examples 1-5 These examples illustrate bloom inhibition in polypropylene compositions containing different levels of elastomeric additives and 4% tris- (3-bromo-2, 2- bis (bromomethyl) propyl) phosphate flame retardant. Results are given in Table 1.
• Example 23-24 These examples illustrate bloom inhibition and flame retardance in a composition that contains a mixture flame retardant materials similar to that disclosed in WO 98/17718. Results are given in Table 6.
• Example 23 24_ Profax ® 6523 88% 83.
• Example 25 26 27 28 Profax ® 6523 76% 73% 70% 73%

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• 1998
  • 1998-11-13 IL IL13611998A patent/IL136119A0/xx unknown
  • 1998-11-13 WO PCT/US1998/024326 patent/WO1999025763A1/en not_active Application Discontinuation
  • 1998-11-13 AU AU14093/99A patent/AU1409399A/en not_active Abandoned
  • 1998-11-13 JP JP2000521140A patent/JP2001523744A/ja active Pending
  • 1998-11-13 EP EP98957959A patent/EP1030877A1/de not_active Withdrawn

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