Classifications

• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
  • C08G65/00—Macromolecular compounds obtained by reactions forming an ether link in the main chain of the macromolecule
  • C08G65/34—Macromolecular compounds obtained by reactions forming an ether link in the main chain of the macromolecule from hydroxy compounds or their metallic derivatives
  • C08G65/48—Polymers modified by chemical after-treatment
  • C08G65/485—Polyphenylene oxides

Definitions

• the present invention relates to capped Thermoplastic polyphenylene ether resins, molding compositions containing said resins, and mixtures of materials and processes for the preparation of the resins.
• polyphenylene ether resins also termed “polyphenylene oxide resins” and “phenoxy polyphenylenoxy phenol resins” are a well-known large and constantly expanding family of linear thermoplastic engineering resins having the theoretical formulas
• X and X' independently represent a substituent or hydrogen
• Y and Y' each independently represent an inert substituent
• n represents a number (usually above 50) which is sufficiently large so that the polymer possesses a desirably high softening point.
• the resins themselves were discovered by Dr. A. S. Hay, and a wide variety of these resins and a number of methods for their preparation are disclosed in Hay U.S. Patent Nos. 3,306,874 and 3,306,875 as well as in Stamatoff U.S. Patent Nos. 3,257,357 and 3,256,358.
• substituents designated by X, X', Y and Y' are not critical so long as they are inert, and a variety of lower alkyl, cycloalkyl, halohydrocarbon, hydrocarbonoxy and halohydrocarbonoxy substituents have been found to be generally useful.
• the polymer molecules are hydroxyl-terminated, and it has recently been found that these sub ⁇ titue ⁇ ts impart certain properties to the resin, which can be improved by "capping" the resin, that is, by esterifying the hydroxyl groups with a monocarboxylic acid, monoacyl halide, or the equivalent, prefer ably after the resins have been reacted with a diphenoquinone; see Hay U.S. Patent No. 4,048,143 and White U.S. Patent No. 4,165,422.
• These resins after being capped, when molded alone or in admixture with customary additives, provide articles which possess outstandingly useful physical properties.
• the compositions are used for the molding of radio and television cabinets, hand tool and household appliance housings, medical and surgical instruments, films, sheets, etc.
• the capping reaction proceeds rapidly at normal extrusion or molding temperature, and that a substantial improvement in the properties mentioned can be effected by merely uniformly mixing the polyphenylene ether resin with an appropriate triaryl phosphite and then feeding the mixture into a commercial thermoplastic extrusion or molding machine having a chamber temperature which is higher than the transesterification point of the mixture and preferably in the range of 400 ⁇ F.-700 ⁇ P. In this range the capping reaction proceeds rapidly without significant degradation of the resin. The capping reaction proceeds while the mixture is passing through the machine, and the fact that a transesterification reaction is taking place is evident from the phenolic odor which is released. Also confirmatory are chromatographic and spectral data.
• the invention thus provides a capped thermoplastic polyphenylene ether resin having the theoretical formula :
• R represents the residue of a polyphenylene ether resin
• a and A' independently represent R or a thermostable aryl substituent containing not more than 10 carbon atoms.
• the polyphenylene ether resin residue has the theoretical formula:
• X, X', Y, Y' and n have the meanings assigned to them above.
• X and X' represent hydrogen and Y and Y' represent methyl, so that the residue is derived from a poly (2,6-dimethyl-1,4-p-ienylene) ether resin prepared by the catalyzed oxidative polymerization of 2,6-xylenol by the method of said Hay patents and having an intrinsic viscosity in the range of about 0.2 to 0.8 dl./g.
• At least one of the substituents A or A' represents R, so that the molecular weight of residue R is in effect doubled.
• the polyphenylene ether resin itself is useful for molding purposes, but more advantageously it is present as a component (and preferably as a predominant component) of a thermoplastic molding composition in particulate free-flowing form.
• the invention further provides a thermoplastic blend of the polyphenylene ether resin in uncapped state and a triaryl phosphite, of the type described below, the molar ratio of the resin to the triaryl phosphite being between about 1:10 and 9:1.
• the resin and the phosphite can be present as separate particles, or the phosphite can be in solution in the resin.
• the latter solution is prepared by dissolving the uncapped polyphenylene ether resin and the triaryl phosphite in a volatile mutual solvent to form a homogeneous solution of the two materials, evaporating the solvent, and comminuting the product. If desired, other compatible and soluble resins can be present in the solution.
• the invention still further provides a method for capping a thermoplastic polyphenylene ether resin which comprises forming a homogeneous melt of the resin and a triaryl phosphite of the type mentioned below and heating the melt at a transesterification temperature until evolution of phenolic matter has substantially ceased.
• the triaryl phosphite is triphenyl phosphite
• the phenolic matter is phenol.
• the capping occurs rapidly when the melt has a temperature between 400°F. and 700°F. in most instances, and in other instances a suitable temperature can be found by laboratory trial.
• the capped resins of the present invention possess a decreased proportion of reactive hydroxyl substituents, and if desired they need possess substantially none o'f these substituents.
• the capped resins possess improved chemical stability, particularly to oxidants, without added disadvantage. This in turn improves the life of molded articles which contain the resin under adverse conditions of service.
• the capped resins are compatible with the widely-used resins of the Noryl type, as well as with polystyrene and copolymers of styrene with butadiene.
• the extent to which, the polyphenylene ether resin should be reacted with the triaryl phosphite depends in part on the extent of the improvement in stability and strength which is desired, and in the time which is available for the reaction.
• the molar ratio of resin to the triaryl phosphite need not be larger than 3:1, as this ratio provides a sufficient amount of the triaryl phosphite(which contains three functional groups) for esterification of substantially all of the hydroxyl substituents of the resin.
• the ratio thus provides a capped resin having the theoretical formula:
• R's represent the polyphenylene ether resin residue, as is shown above. Capped resins of this formula generally possess all the benefits of the present invention.
• the ratio of the polyphenylene ether resin to the triaryl phosphite can be decreased considerably without more than a slight loss of benefit.
• the resin:phosphite molar ratio can be as low as about 2:1.
• the capped resin has the theoretical formula:
• R's represent the polyphenylene ether resin residue and Ar represents one of the substituents of the starting triaryl phosphites. This ratio provides an effective doubling of the molecular weight of the starting resin as well as a substantial increase in stability.
• the molar ratio of the resin to the triaryl phosphite can be decreased still further, to the range of about 1:1. This ratio provides a capped polyphenylene ether resin which hasthe theoretical formula:
• the polyphenylene ether resin and the triaryl phosphite are supplied as an unreacted blend to the molding or extrusion machine.
• the capping reaction proceeds to a satisfactory extent in the brief time during which these components are in molten state in the molding machine.
• the conditions required for a substantially complete transesterification reaction are an adequately long time at a sufficiently high temperature, and usually these conditions are easily met within a commercial extrusion or molding machine. It is advantageous in some cases to provide a substantial excess of the triaryl phosphite so as to force the transesterification reaction in the desired direction, an excess of 10 to 50 mol percent being preferred.
• the preferable proportion of triaryl phosphite which need be added in any instance depends, in addition to the variables mentioned above, on the chain length or molecular weight of the polyphenylene ether resin, short chain length resins requiring a larger weight percent of the triaryl phosphite, than the longer chain length resins.
• the preferable proportion in any instance can be rapidly found by making a series of laboratory trials along the lines shown in the examples below.
• Suitable triaryl phosphites for capping the polyphenylene ether resins are the phosphorus acid triesters of phenols which contain not more than 10 carbon atoms. Phosphites of this group are non-volatile at temperatures at which the polyphenylene ether resins are molten but below their decomposition points, yet the phenolic components, when released, are volatile in this temperature range and so cause the transesterification reaction to proceed in the desired direction.
• Suitable phosphites include tri (p-aminothiophenyl) phosphite, tri- (o-bromo- phenyl) phosphite, tri (o-chlorophenyl) phosphite, tri-o-iso- propylphenyl phosphite, triguaiacyl phosphite, tricresyl phosphite, tri (dimethoxyphenyl) phosphite, tri-(2,4-dichlorophenyl) phosphite, tri-(2,6-diidophenyl) phosphite, tri-o-isopropyl- phenyl phosphite, and tri (thibphenyl) phosphite.
• Triphenyl phosphite is preferred because this ester has a sufficiently high boiling point (245 ⁇ C, 473 ⁇ F.) to permit it to remain in a polyphenylene ether resin melt without more than negligible volatilization, and yet the transesterifcation product (phenol) has a sufficiently low boiling point (approximately 182°C.) so that it volatilizes rapidly and completely as soon as it is formec.
• the transesterification can be performed within a few minutes in an open reaction vessel at about the minimum temperature at which preferred polyphenylene ether resins form a fluid mix.
• the capped polyphenylene ethers of the present invention can be molded alone to provide useful articles, or they can be and preferably are molded in admixture with any of the modifying polymers, plasticizers, stabilizers, fire retardants, fillers, strengthening agents and pigments which have been used in the past in conjunction with thermoplastic molding resins.
• the capped polyphenylene ether resins can be molded in admixture with polystyrene, styrene-butadiene, copolymers, polyethylene, zinc oxide, zinc sulfide, asbestos fibers, glass fibers, carbon whiskers, ground walnut shells, carbon black, titanium dioxide pigment, etc., in any of the customary proportions.
• the polyphenylene ether resin's which can be used as the starting materials of the present invention may be of customary engineering molecular weight, usually expressed as an intrinsic viscosity in the range of 0.20 to 0.80 dl./g. as determined in CHCI 3 at 30 ⁇ C. it is an important feature of the invention, however, that the polyphenylene ether resins which have a molecular weight which is too low to permit them to be used for structural purposes, i.e., resins which have intrinsic viscosities in the range of about 0.20 to 0.40 dl./g., can be rendered suitable for structural purposes by the present invention.
• a sufficient proportion of the triaryl phosphite is used so that the diester or triester is formed from substantially all of the resin, as is shown above.
• This permits the conversion of a comparatively low molecular weight starting polyphenylene ether resin into a capped product which has about twice the original molecular weight and which therefore possesses a much higher softening point and so provides a molded article having a higher impact resistance and greater elasticity.
• the starting polyphenylene ether resin is of engineering molecular length, the capping procedure, performed to best advantage as described, provides resin which is of still better quality.
• capped resin can be determined directly by conventional analytical techniques, for example, by 31 p and 13 C nuclear magnetic resonance spectra, by determining the amount of increase in the intrinsic viscosity of the resin, and by the use of GPC data.
• proportion of the polyphenylene ether resin which is esteri fied in any instance can be determined by recovering the evolved phenol or other released component of the triaryl phosphite and calculating therefrom the number of aryl groups of the phosphite which have reacted. These data in turn will permit determination of the percentage of the hydroxyl substituents of the resin which have undergone esterification.
• the capped polymer can be recovered in high yield from the crude reaction product by dissolving the reaction product in a sufficiently large amount of toluene to form a fluid solution and then adding cold methanol.
• the capped polymer precipitates and can be recovered by filtration, centrifugation, etc., followed by a washing with methanol.
• the following illustrates the preparation of a capped polyphenylene ether resin by transesterification of the resin with a triaryl phosphite, showing the effectiveness of a preferred triaryl phosphite in comparison with other phosphites.
• PPO powdered polyphenylene ether resin having an intrinsic viscosity of 0.48 dl./g.
• the products of the above runs A-D are separated into their polyphenylene ether resin and polystyrene components.
• the intrinsic viscosity of the polystyrene is substantially constant.
• the increases in intrinsic viscosity are due to increases in the intrinsic viscosities of the polyphenylene ether resin, resulting from the capping reaction.
• EXAMPLE 2 The following illustrates the preparation of a molding composition having a substantial content of a polyphenylene ether resin capped by reaction with a triaryl phosphite and the properties of a test piece molded therefrom, in comparison with a test piece molded from a similar composition prepared by use of a polyphenylene ether resin containing a trialkyl phosphite.
• A The following are dry blended in powdered form: Polyphenylene ether resin (high molecular weight; intrinsic viscosity 0.45 dl.g.) 50 parts Polystyrene-butadiene copolymer (high impact type, Foster-Grant Co. No. 834) 50 Triphenyl phosphite 0.83 Polyethylene 1.5 Triphenyl phosphate (plasticizer) 3.0 Zinc oxide 0.15 Zinc sulfide 0.15 Titanium dioxide pigment 3.0 The resulting free-flowing particulate composition is extruded and molded into test bars by the procedure of Example 1. The pieces have a notched Izod impact strength of 3.8 ft.-lb./in. and a 62% elongation at break.
• the molded product has a notched Izod impact strength of 3.3 ft.-lb./in.
• Procedure A (control). Procedure A is repeated except that the triphenyl phosphite is replaced by 1.00 part of decyldiphenyl phosphite (equimolar amount). The product has a notched Izod impact strength of 2.2 ft.-lb./in.

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• 1981
  • 1981-12-18 WO PCT/US1981/001700 patent/WO1983002117A1/fr not_active Application Discontinuation
  • 1981-12-18 EP EP19820900463 patent/EP0097152A4/fr not_active Withdrawn
  • 1981-12-18 AU AU80855/82A patent/AU8085582A/en not_active Abandoned
  • 1981-12-18 JP JP82500550A patent/JPS58502150A/ja active Pending

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