High flow polyphenylene ether formulations

Details High flow polyphenylene ether formulations High flow polyphenylene ether formulations

2000-04-12

2003-06-10

Short, Patricia A. (Department: 1712)

Synthetic resins or natural rubbers -- part of the class 520 ser

Synthetic resins

At least one aryl ring which is part of a fused or bridged...

C524S115000, C524S125000, C524S127000, C524S139000, C524S141000, C524S504000, C524S505000, C524S538000, C524S539000, C524S540000, C525S390000, C525S397000, C525S132000, C525S133000

Reexamination Certificate

active

06576700

ABSTRACT:

BACKGROUND OF THE INVENTION
This invention relates to high flow polyphenylene ether formulations with improved properties.
BRIEF DESCRIPTION OF RELATED ART
Polyphenylene ether resins (PPE) are an extremely useful class of high performance engineering thermoplastics by reason of their hydrolytic stability, high dimensional stability, toughness, heat resistance and dielectric properties. They also exhibit high glass transition temperature values, typically in the range of 150° to 210° C., and good mechanical performance. This unique combination of properties renders polyphenylene ether based formulations suitable for a broad range of applications which are well known in the art. One example is injection molded products which are used for high heat applications. Polyphenylene ether polymers typically have relatively high molecular weights and possess high melt viscosity with intrinsic viscosity values typically greater than about 0.3 dl/g, as measured in chloroform at 25° C.
One area in which polyphenylene ether based compositions have required an improvement is melt flow capability, i.e. the ability to flow freely at elevated temperatures during various processing stages such as extrusion and molding. Poor melt flow can impact the size and type of part which can be prepared with the composition. In U.S. Pat. No. 4,154,712 to G. Lee, Jr. teaches that processability can be improved by decreasing the molecular weight of the polyphenylene ether polymers; however, lower molecular weight sometimes adversely affects other properties such as impact strength. To aid processing, polyphenylene ether resins are often prepared with flow promoters such as polystyrene, high impact polystyrene, saturated polyalicyclic resins and terpene phenol to impart high flow to the resulting composition. Polystyrene, terpene phenol and other such flow promoters reduce the heat deflection temperature (HDT) of the product and typically increase the flammability of the PPE resin, as measured under UL94 standard protocol.
Polyphenylene ether resins are often flame retarded with phosphorous containing organic compounds such as resorcinol diphosphate, Bisphenol-A diphosphate and tetraxylyl piperazine diphosphoramide to comply with Eco-label guidelines. The fire retardant grades of polyphenylene ether, particularly those rated UL94 V0, tend to be formulated using large amounts of flame retardant additives. The addition of large amounts of these phosphorous containing organic compounds reduces the heat deflection temperature (HDT) of the formulation even further.
Efforts to improve the flow characteristics of PPE resins with minimal or no loss of HDT values and impact properties have been made. For example, U.S. Pat. No. 5,376,724 to Bailey et al. discloses polyphenylene ether compositions which contain a resinous additive that improves flow with only minor reductions in HDT values and impact strength. The resinous additive is said to be comprised of vinyl aromatic monomers such as styrene monomers or a hydrocarbon compound containing at least 35 wt % aromatic units.
In addition, U.S. Pat. No. 5,081,185 to Haafet al. describes compositions comprising a blend of two or more polyphenylene ether resins with one resin having high intrinsic viscosity values of at least about 0.38 dl/g and the other having low intrinsic viscosity values of no greater than 0.33 dl/g. The blend of the two PPE resins exhibits higher melt flow with no substantial decrease in heat deflection temperature (HDT) when compared to the high intrinsic viscosity PPE resin of the blend. Haaf et al. provides no special means for isolating low I.V. PPE resins from a reaction solution. In conventional isolation techniques, the PPE reaction solution, typically in toluene, is added to a non-solvent, such as methanol, to precipitate the PPE resin product. These non-solvent precipitation techniques provide very fine particles when applied to low I.V. PPE resins. These fine particles have very low bulk densities and are difficult to feed into extruders and other processing equipment. Consequently, the compositions taught by Haaf have limited commercial utility due to poor compounding throughputs and often erratic operation. Fine particles are also formed when isolating ultra-low viscosity PPE resins, e.g., PPE having an I.V. of less than about 0.27 dl/gm as measured in chloroform at 25° C., from solution by precipitation with a non-solvent.
It is desirable to provide a high flow PPE resin composition with improved flame retardance as well as improved HDT values and impact properties. Additionally it is desirable to develop improved methods to manufacture such compositions.
SUMMARY OF THE INVENTION
The present invention provides blends of polyphenylene ether resins which comprise a Component A and a Component B. Component A is a polyphenylene ether resin preferably having an intrinsic viscosity of at least about 0.3 dl/g, most often in the range of about 0.4-0.6 dl/g, as measured in chloroform at 25° C. This polyphenylene ether resin can comprise one or more different polyphenylene ether polymers. Component B is an ultra low viscosity polyphenylene ether resin having an intrinsic viscosity of no greater than about 0.25 dl/g, preferably no greater than about 0.17 dl/g, as measured in chloroform at 25° C. This resin can also comprise one or more different polyphenylene ether polymers. It has been discovered that improvements in the flow properties of compositions containing polyphenylene ether resins can be obtained with smaller decreases in HDT values and flammability when ultra low viscosity polyphenylene ether resins are added instead of conventional flow modifying additives.
The polyphenylene ether polymers employed in Components A and B of the PPE blends of the present invention are known polymers comprising a plurality of aryloxy repeating units preferably with repeating units of Formula I
wherein in each of said units independently, each Q
1
is independently halogen, alkyl (preferably primary or secondary lower alkyl containing up to 7 carbon atoms), aryl (preferably phenyl), halohydrocarbon groups (preferably haloalkyl) having at least two carbons between the halogen atoms and the phenyl nucleus of Formula I, aminoalkyl, hydrocarbonoxy or halohydrocarbonoxy wherein at least two carbon atoms separate the halogen and oxygen atoms and at least two carbon atoms separate the halogen atoms and the phenyl nucleus of Formula I.
Each Q
2
is independently hydrogen, halogen, alkyl (preferably primary or secondary lower alkyl up to 7 carbon atoms), aryl (preferably phenyl), halohydrocarbon (preferably haloalkyl) having at least two carbon atoms between the halogen atoms and the phenyl nucleus of Formula I, hydrocarbonoxy groups or halohydrocarbonoxy groups wherein at least two carbon atoms separate the halogen and oxygen atoms and at least two carbon atoms separate the halogen atoms from the phenyl nucleus of Formula I. Q
1
and Q
2
suitably contain up to about 12 carbon atoms and most often, each Q
1
is an alkyl or phenyl, especially C
1
-C
4
alkyl and each Q
2
is hydrogen.
The term “polyphenylene ether resin,” as used in the specification and claims herein, includes unsubstituted polyphenylene ether polymers, substituted polyphenylene ether polymers (wherein the aromatic ring is substituted), polyphenylene ether copolymers and blends thereof. Also included are polyphenylene ether polymers containing moieties prepared by grafting onto the polyphenylene ether in a known manner such materials as vinyl monomers or polymers such as polystyrenes and elastomers, as described in U.S. Pat. No. 5,089,566 issued to Sterling Brown. Coupled polyphenylene ether polymers in which coupling agents such as low molecular weight polycarbonates, quinones, heterocycles and formals undergo reaction in the known manner with the hydroxy groups of two phenyl ether chains to produce a high molecular weight polymer are also included.
The polyphenylene ether polymers used in Components A and B of the PPE blends of this invention may also have various end groups such as amino alkyl co

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