Celanese Gmbh

Frank M Berardinelli

Robert Edelman

Norman W Thomas

Kurt F Wissbrun

Robert W Stackman

David E Cincotta

Rufus S Jones, Jr

An improved process for producing a polymer blend which exhibits an anisotropic melt phase and is capable of forming shaped articles having satisfactory mechanical properties (e.g. tensile strength, flexural strength, and Izod impact strength) is provided. The process comprises the steps of (a) post-polymerizing a melt processable wholly aromatic polyester which is capable of forming an anisotropic melt phase apart from the blend and (b) subsequently intimately mixing together approximately 85 to 95 percent by weight of the wholly aromatic polyester and approximately 5 to 15 percent by weight of a polyalkylene terephthalate. Accordingly, the wholly aromatic polyester which is capable of forming an anisotropic melt phase serves as the continuous phase in the resulting blend. The post-polymerization step is conducted at a temperature and for a period of time sufficient to increase the inherent viscosity of the wholly aromatic polyester by at least approximately 50 percent, preferably by at least approximately 100 percent. Each of the shaped article mechanical properties identified above is improved over that of the composition in the absence of the polyalkylene terephthalate. The polyalkylene terephthalate is preferably polyethylene terephthalate.

Process for forming blend of polyalkylene terephthalate and wholly

A process is provided for forming a novel polymer blend which exhibits an anisotropic melt phase wherein there is chemical interaction between previously formed polymeric blend components to yield a product which is capable of forming shaped articles having highly satisfactory mechanical properties. The process comprises intimately mixing together approximately 50 to 75 percent by weight of polyalkylene terephthalate and 25 to 50 percent by weight of a melt processable polyester which is capable of forming an anisotropic melt phase. A post-polymerization subsequently is conducted in the solid phase in a non-oxidizing atmosphere at a temperature within the range of approximately 250.degree. to 300.degree. C. for a period of time in the range approximately 8 to 72 hours to yield the desired chemical interaction between the previously formed polymeric blend components.

Blend of polyalkylene terephthalate and wholly aromatic polyester and

A process for the production of high molecular weight oxymethylene copolymer in the presence of impurity is provided. The process provides a high molecular weight oxymethylene copolymer having a predetermined comonomer content. The process comprises the steps of determining the optimal catalyst concentration in a first oxymethylene copolymerization system which contains less than approximately 10 p.p.m. impurity; determining the concentration of impurity containing at least one active proton in a second copolymerization system; adjusting the catalyst concentration in the second copolymerization system so that the total concentration of catalyst and impurity in the second copolymerization system is maintained at the optimal concentration of catalyst in the first copolymerization system; and adjusting the concentration of comonomer in the second copolymerization system so as to maintain the predetermined comonomer content in the oxymethylene copolymer product.

Process for the production of high molecular weight oxymethylene

A process is disclosed for producing a modified polyethylene iso-terephthalate copolymer which may be processed into plastic containers using conventional extrusion blow molding equipment. The copolymer is modified by the incorporation into a polyethylene iso/terephthalate prepolymer of a chain branching agent and a chain terminating agent. The prepolymer is subsequently solid-state polymerized to form a polyethylene iso/terephthalate copolymer having high zero shear rate melt viscosity and shear sensitivity. This modified copolymer is transparent when extrusion blow molded into a shaped article. The modified copolymer may be extrusion blow molded in intermittent and continuous processes.

Extrusion grade polyethylene iso/terephthalate copolymer

A process is disclosed for modifying polyethylene terephthalate so that the polyethylene terephthalate may be processed into plastic containers using conventional extrusion blow molding equipment. The polyethylene terephthalate is modified by the incorporation into a polyethylene terephthalate prepolymer of a chain branching agent and a chain terminating agent. The prepolymer is subsequently solid-state polymerized to form a polyethylene terephthalate polymer having high zero shear rate melt viscosity and shear sensitivity. This modified polyethylene terephthalate polymer may be extrusion blow molded in intermittent and continuous processes.

Extrusion grade polyethylene terephthalate

There is disclosed a process for preparing polycarbodiimide modified tractable polyamides having unique rheological properties which include increased melt strength and relative viscosity. These polycarbodiimide modified tractable polyamides are prepared by reacting the carboxyl end groups and to a lesser degree the amine end groups of tractable polyamides such as nylon 6,6, which are in a molten state with the polycarbodiimide groups of at least one polycarbodiimide such as poly(4,4'-diphenyl-methane carbodiimide) which both (a) is derived from at least one aromatic diisocyanate which is either unsubstituted or contains up to one methyl substituent on each aromatic ring, and (b) contains at least three carbodiimide units per polycarbodiimide molecule. The resulting polycarbodiimide modified tractable polyamide has improved melt strength and relative viscosity and a decreased number of carboxylic acid and amine end groups. These improved melt strength polyamides also have improved die swell and shear sensitivity characteristics and are generally useful in extrusion applications such as blow molding.

Polyamides for extrusion applications

Molding resin compositions comprising a polycarbodiimide modified polyalkylene terephthalate polymer (polypropylene terephthalate, polybutylene terephthalate, or mixtures thereof) and a reinforcing agent such as glass fibers have been found to exhibit improved impact strength and thus are useful in various molding applications in order to prepare articles of manufacture having, e.g., industrial (e.g., gears, bearings), automotive (e.g., automotive distributor caps, distributor rotors), and electrical (e.g., motor end caps, brush holders) applications. These molding resin compositions are particularly useful in certain automotive, industrial, and electrical applications where greater impact strength may be required to extend the useful life of various articles of manufacture which may be subjected to occasional or continuous shock or impact. These molding resin compositions may be prepared by intimately admixing in the molten state a reinforcing agent such as glass fibers with a polycarbodiimide modified polyalkylene terephthalate polymer formed from the reaction between a polyalkylene terephthalate polymer which is the reaction product of terephthalic acid or a dialkyl ester of terephthalic acid and a glycol selected from the group consisting of trimethylene glycol, tetramethylene glycol, and mixtures thereof, and a polycarbodiimide which is both (1) derived from at least one aromatic diisocyanate which is either unsubstituted or contains up to one methyl substituent on each aromatic ring, and (2) contains at least two carbodiimide units per polycarbodiimide molecule. The components of the composition are preferably prepared by charging the polyalkylene terephthalate to the hopper of a melt screw extruder and adding the polycarbodiimide and reinforcing agent downstream in the extruder--e.g., in the vent port or other side feed port of the extruder.

Reinforced polycarbodiimide modified polyalkylene terephthalate

There is disclosed a process for preparing polycarbodiimide modified thermoplastic polyesters having unique rheological properties which include increased intrinsic viscosity and melt strength. These polycarbodiimide modified thermoplastic polyesters are prepared by reacting the carboxyl end groups of thermoplastic saturated polyesters which are in a molten state with the polycarbodiimide groups of at least one polycarbodiimide such as poly (4,4'-diphenyl-methane carbodiimide) which both (a) is derived from at least one aromatic diisocyanate which is either unsubstituted or contains up to one methyl substituent on each aromatic ring, and (b) contains at least three carbodiimide units per polycarbodiimide molecule. The resulting polycarbodiimide modified thermoplastic polyester has improved melt strength and intrinsic viscosity and a decreased number of carboxylic acid end groups. These improved melt strength polyesters also have improved die swell and shear sensitivity characteristics and are generally useful in extrusion applications such as blow molding.

Polycarbodiimide modification of polyesters for extrusion applications

There is disclosed a process for preparing reinforced flame retardant copolyester molding compositions having non-drip characteristics. This process comprises intimately mixing a reinforcing agent, a Group Vb metal-containing compound, and the molten reaction product of a copolyester and a polycarbodiimide. The copolyester comprises the reaction product of (a) an alkane diol (as defined), (b) terephthalic acid, isophthalic acid or a dialkyl ester thereof, and (c) a halogenated derivative of the bishydroxyethylether of p,p'-isopropylidenediphenol. The polycarbodiimide must both (a) be derived from at least one aromatic diisocyanate which is either unsubstituted or contains up to one methyl substituent on each aromatic ring, and (b) contains at least three carbodiimide units per polycarbodiimide molecule. The reinforced flame retardant copolyester molding resin composition prepared by this process may be readily molded to form three-dimensional shaped articles having satisfactory mechanical properties using conventional molding techniques.

Reinforced flame retardant polyester composition having non-drip

An improved flame retardant molding composition of polypropylene terephthalate or polybutylene terephthalate is provided. The composition includes in intimate admixture with the non-halogenated polypropylene terephthalate or polybutylene terephthalate an oxide of antimony, a reinforcing agent (e.g. a glass fiber reinforcing agent), and a polyalkylene-2,5-dibromoterephthalate. Unlike the flame retardant molding compositions of the prior art, the components of the same tend to be non-exuding during utilization of the resulting three-dimensional shaped article at elevated temperatures (e.g. after 66 hours at 175.degree. C.) and thereby render the same suitable for attractive utilization in an even wider range of applications.

Molding composition suitable for forming improved flame retardant

An improved thermoplastic molding resin comprising intimately blended polybutylene terephthalate polymers or polypropylene terephthalate polymers, and reinforcing agents in the presence of a thermoplastic phenoxy resin.

Polyalkylene terephthalate polymer molding resins

An improved flame retardant molding composition of polypropylene terephthalate or polybutylene terephthalate is provided. The composition includes in intimate admixture an oxide of antimony and a specific brominated aromatic polyphosphate copolymer which has been found to be highly compatible with the other components. In a preferred embodiment the molding composition additionally includes a reinforcing agent (e.g. a glass fiber reinforcing agent). Unlike the flame retardant molding compositions of the prior art, the components of the same tend to be non-exuding during utilization of a resulting three-dimensional shaped article at elevated temperatures (e.g. after 66 hours at 175.degree.C.) and thereby render the same suitable for attractive utilization in an even wider range of applications.

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Millington, NJ, United States of America

Frank M Berardinelli