Classifications

• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • C08L67/00—Compositions of polyesters obtained by reactions forming a carboxylic ester link in the main chain; Compositions of derivatives of such polymers
  • C08L67/02—Polyesters derived from dicarboxylic acids and dihydroxy compounds
• • 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
  • C08K3/00—Use of inorganic substances as compounding ingredients
  • C08K3/01—Use of inorganic substances as compounding ingredients characterized by their specific function
  • C08K3/013—Fillers, pigments or reinforcing additives

Definitions

• This invention relates to improved flame-retardant thermoplastic molding compositions and, more particularly, to improved thermoplastic polyester molding compositions and to a process for enhancing their electrical arc track resistance.
• polyethylene terephthalate polyethylene terephthalate
• Poly(1,4-butylene terephthalate) because of its very rapid crystallization from the melt, is uniquely useful as a component in such compositions.
• block copolyesters wherein the major portion of the repeating units are poly(1,4-butylene terephthalate) blocks, have been found to have enhanced impact resistance. See copending application U.S. Serial No. 752,325, filed December 20, 1976. Enhanced impact resistance has also been reported when poly(l,4-butylene terephthalate) and block copolyesters have been combined with impact modifiers comprising resins, e.g., block copolymers of vinyl aromatics and dienes, in combination with aromatic polycarbonate resins and a mineral filler. Flame retardant such compositions are also known. See copending application, U.S. Serial No. 966,864, filed December 6, 1978.
• Stable polyblends of poly(1,4-butylene terephthalate) and poly(ethylene terephthalate) can be molded into useful unfilled and filled articles. See Fox and Wambach, U.S. 3,953,394.
• poly(1,4-butylene terephthalate) resins are known to be suitable for combination with glass fiber reinforcement and/or flame retardant agents.
• U.S. Patent No. 3,937,757 teaches that the electrical arc tracking resistance of unfilled poly(l,4-butylene terephthalate) compositions can be improved by the addition of from 5 to 50% by weight of a polyolefin or ethylene copolymer, containing at least 50% by weight ethylene units, thereto.
• thermoplastic compositions which are useful for molding or extrusion, e.g., injection molding, injection blow molding, compression molding, trans.fer molding, profile extrusion, sheet extrusion, wire coating, extrusion blow molding and the like, the compositions having improved physical properties, such as impact resistance, and electrical properties, such as arc track resistance, the compositions comprising an intimate admixture of:
• the high molecular weight poly(l,4-butylene terephthalates), preferably high molecular weight linear such polyesters, used in the practice of the present invention are polymeric 1,4butanediol esters of terephthalic acid and may include minor amounts of glycol esters of other difunctional acids, such as isophthalic, adipic, and the like. They are available commercially or can be prepared by known techniques, such as by the alcoholysis of esters of terephthalic acid with 1,4-butanediol and subsequent polymerization, by heating the diol with the free acids or with halide derivatives thereof, and similar processes. These are described in U.S. 2,465,319 and U.S. 3,047,539, and elsewhere.
• the glycol portion of the polyester can contain minor proportions of the glycols from two to ten carbon atoms.
• the high molecular weight poly(butylene terephthalate) (PBT) will have an intrinsic viscosity of at least 0.7 deciliters/gram as measured in a 60:40 phenol tetrachloroethane mixture at 30oC. At intrinsic viscosities of at least about 0.9 deciliters/gram for PBT, there is a further enhancement in toughness of the present compositions.
• Block copolyesters are also useful in the compositions of this invention. These are generally prepared by the reaction of terminally-reactive poly(butyleneterephthalate), preferably, low molecular weight, and a terminally-reactive copolyester or polyester in the presence of a catalyst for transesterification, such as zinc acetate, manganese acetate, titanium esters, and the like.
• the terminal groups can comprise hydroxyl, carboxyl, carboalkoxy, and the like, including reactive derivatives thereof.
• polymerization is carried out under standard conditions, e.g., 220 to 280oC, in a high vacuum, e.g., 0.1 to 2mm Hg, to form the block copolymer of minimum randomization in terms of distribution of chain segments.
• standard conditions e.g., 220 to 280oC
• a high vacuum e.g., 0.1 to 2mm Hg
• block copolyesters are described in copending U.S. application Serial No. 752,325, filed on December 20, 1976, incorporated herein by reference.
• these block copolyesters are derived from
• a terminally-reactive aromatic/aliphatic copolyester of a dicarboxylic acid selected from the group consisting of terephthalic acid, isophthalic acid, naphthalene dicarboxylic acids, phenyl indane dicarboxylic acid and compounds of the formula:
• X may be alkylene or alkylidene of from 1 to 4 carbon atoms, carbonyl, sulfonyl, oxygen or a bond between the benzene rings, and an aliphatic dicarboxylic acid having from 6 to 12 carbon atoms in the chain and one or more straight or branched chain dihydric aliphatic glycols having from 4 to 10 carbon atoms in the chain, said copolyester having at least 10% of aliphatic units being derived from a dicarboxylic acid, or (iii) a terminally-reactive aliphatic polyester of a straight chain aliphatic dicarboxylic acid having from 4 to 12 carbon atoms in the chain and a straight or branched chain aliphatic glycol, said blocks being connected by inter-terminal linkages consisting essentially of ester linkages;
• the copolymers of ethylene and vinyl acetate useful in the practice of this invention may be derived from two or more monomers.
• the term "copolymers" herein is intended to include terpolymers and so on.
• Illustrative copolymers of ethylene and vinyl acetate contemplated herein include, for example, Alathon 3892, now referred to as Alathon 3194 (25% by weight vinyl acetate, 75% by weight ethylene), Alathon 3152 (15% by weight vinyl acetate, 85% by weight ethylene), Alathon 3180 (287.
• Vynathene EY903 45% by weight vinyl acetate, 55% by weight ethylene
• Vynathene EY904 52% by weight vinyl acetate and 48% by weight ethylene.
• the Alathons are products of the DuPont Chemical Co. and the Vynathenes are products of U.S.I. Chemicals.
• terpolymers useful herein are included, for example, those prepared from ethylene, vinyl acetate and carbon monoxide (ELVALOY 741 or 742, sold by DuPont), ethylene, vinyl acetate and methacrylic acid and ethylene, vinyl acetate and acrylic acid (ELVAX 4260 and 4355 available from DuPont), and the like.
• the aromatic polycarbonate resins can be made in known ways and they are available from commercially from sources, e.g., General Electric Company, Pitt ⁇ field, Massachusetts, under the trademark LEXAN. In general, any of the aromatic polycarbonates described in Baron et al., U.S.
• 4,034,016 can be used, especially those including units derived from bisphenol-A.
• the poly(ethylene terephthalate) resins can be made in known ways and they are available from commercial sources, e.g., Goodyear Company, under the trademark VITUF, e.g., VFR-738-A7C.
• VITUF e.g., VFR-738-A7C.
• the intrinsic viscosity will be above about 0.4 deciliters/gram and preferably above about 0.6 deciliters/gram, as measured in a 60:40 phenoltetrachloroethane mixture at 30oC.
• component (b) (iii) With respect to component (b) (iii), conventional glass fiber reinforcement is used. This is available commercially from a number of sources. The grades suitable for electrical end uses are preferred.
• components (b) (i) and (b)(ii) are employed in amounts of from about 0.1 to about 25% by weight of the total composition. Particulary preferred amounts for best overall properties are in the range of from about 3 to about 15% by weight. Reinforcing amounts of component (b) (iii) will range from about 2 to about 507. by weight and preferably from about 10 to about 40% by weight of the total composition.
• the conventional flame retardant additive (c) is well known. These will be based on elementary red phosphorus, phosphorus compounds, halogen or nitrogen compounds alone or preferably in further combination with synergists, such as antimony compounds. Especially useful are polymeric and oligomeric flame retardant agents comprising tetrabromobisphenol-A carbonate units. See, for example Wambach, U.S. 3,833,685. Also preferred are halogenated aromatic ethers, such as decabromodiphenyl ether, or poly(2,6-dibromo-1,4-phenylene)ether, and the like. The amounts used are conventional and well known. For example, component (c) can comprise from 3 to 20%, preferably from 5 to 15% by weight of the total weight of the composition.
• a wide variety of mineral fillers can be used in the thermoplastic compositions of this invention.
• these fillers are included clays, like kaolin and calcined clays, silicas, such as novaculites, ground sands and amorphous glasses; mica, talc, pyrophillites, mineral wools, wollastonites and mixtures of the same.
• Clays and especially treated kaolin clays, such as that known as Translink-445, available from the Freeport Kaolin Company, silica, talc and mica are preferred herein. Amounts of from about 5% to about 40% by weight of the total composition, of mineral filler are contemplated herein.
• mineral filler Preferably 10-30% by weight of mineral filler is used.
• Typical treating agents for the mineral fillers are gamma-aminopropyltriethoxysilane, gamma-glycidoxypropyltrimethoxysilane, and beta-(3,4-epoxycyclohexyl)ethyltrimethoxysilane.
• ingredients such as dyes, pigments, drip retardants, and the like, can be added for their conventionally employed purposes.
• compositions of this invention can be prepared by a number of procedures. The best way is to form an intimate admixture of components (a), (b) and (c) in the presence of an effective amount of mineral filler (d). They can for example be put into an extrusion compounder to produce molding pellets.
• the modifiers and mineral filler are dispersed in a matrix of the polyester resin in such a process.
• the polyester(s), modifier and mineral filler are mixed by dry blending, then either fluxed on a mill and comminuted, or then are extruded and chopped.
• the mineral filler can also be mixed with the resins and modifiers and directly molded, e.g., by injection or transfer molding techniques, but this is not preferred.
• compounding should be carried out to ensure that the residence time in the machine is short; the temperature is carefully controlled; the friction heat is utilized; and an intimate blend between the resin, the modifier, the flame retardant additive and the mineral filler is obtained.
• Pre-compounding can be carried out in conventional equipment. For example, after carefully pre-drying the polyester and modifier and the mineral filler, e.g., 4 hours at 250oF., a single screw vacuum vented extruder is fed with a dry blend of the ingredients, the screw employed having a long transition section to ensure proper melting. On the other hand, a twin screw machine, e.g., a 53 mm. Werner Pfleiders machine can be fed with resin and additives at the feed port and mineral filler downstream. In either case, a generally suitable machine temperature will be about 450-560oF.
• the pre-compounded composition can be extruded and cut up into molding compounds such as conventional granules, pellets, etc., by standard techniques.
• compositions can be molded in any equipment conventionally used for glass-filled thermoplastic compositions, e.g., a Newberry type injection molding machine with conventional cylinder temperatures, e.g., 450-535oF. and conventional mold temperatures, e.g., 130-200oF.
• a Newberry type injection molding machine with conventional cylinder temperatures, e.g., 450-535oF. and conventional mold temperatures, e.g., 130-200oF.
• a dry blend of poly(1,4-butylene terephthalate), ethylene-vinyl acetate copolymer, aromatic polycarbonate, flame retardant additive, mineral filler and mold release/stabilizer is compounded and extruded at 525oF. in an extruder.
• the extrudate is pelletized and injection molded at 490oF. (mold temperature
• Table 1 Compositions Comprising Polyester, Ethylene Vinyl Acetate Copolymer, Polycarbonate, Flame Retardant and Mineral Filler.
• Example 1 1A* Composition (parts by weight)
• Example 2 The general procedure of Example 1 is used to prepare compositions of poly(1,4-butylene terephthalate) modified with poly(ethylene terephthalate), flame retardant agent and including mineral filler. For comparison purposes, a composition without mineral filler is prepared and tested. The formulations and properties are shown in Table 2.
• Composition (parts by weight) 2 2A* 3 4 5 6
• Stabilizers (to make 100) 0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.2
• Example 1 The general procedure of Example 1 is used to prepare compositions of poly(1,4-butylene terephthalate) glass fibers, flame retardant agents and mineral fillers. For comparison purposes, a composition without mineral filler is prepared and testedd The formulations used and the properties are shown in Table 3.
• composition parts by weight

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• 1980
  • 1980-04-23 BR BR8008657A patent/BR8008657A/pt unknown
  • 1980-04-23 JP JP50121580A patent/JPS56500416A/ja active Pending
  • 1980-04-23 WO PCT/US1980/000450 patent/WO1980002430A1/en not_active Application Discontinuation
  • 1980-05-01 AU AU57971/80A patent/AU533840B2/en not_active Ceased
  • 1980-11-17 EP EP19800901027 patent/EP0027464A4/en not_active Withdrawn

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