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
  • C08G65/38—Macromolecular compounds obtained by reactions forming an ether link in the main chain of the macromolecule from hydroxy compounds or their metallic derivatives derived from phenols
  • C08G65/44—Macromolecular compounds obtained by reactions forming an ether link in the main chain of the macromolecule from hydroxy compounds or their metallic derivatives derived from phenols by oxidation of phenols

Definitions

• the present invention relates to the manufacture of polyphenylene ether resins, and particularly relates to a method of controlling the rate at which heat is formed during the batch manufacture of these resins by the 5 catalyzed oxidation polymerization of hindered phenols.
• polyphenylene ether resins are a well-known large family of thermoplastic engineering plastics which alone and in admixture with modifying polymers,, lubricants, 10 fillers, pigments, etc., have found wide commercial use for the manufacture of articles which possess excellent impact resistance and resistance to high temperatures, organic solvents, and water.
• the articles include radio and television cabinets, hand tool and household appliance 15 housings, medical and surgical instruments, electric motor and automobile components, films, sheets, etc.
• the polymers are substantially composed of units having the theoretical formula:
• Ar represents an aryl unit, the ether oxygen atom of one unit being connected to the next adjacent aryl unit, and n is a value sufficiently large (usually at least 50) so that the polymer has a softening point which is sufficiently high for the intended use of the polymer,
• the resins are generally prepared by the oxidative coupling in a volatile organic solvent containing the catalyst of one or more hindered phenols of the structure: wherein X and X' each designate an inert substituent and H (hydrogen) , and Y and Y' each designate an inert substituent.
• Methods for the preparation of the polymers and a wide variety of suitable catalysts and starting phenols are disclosed in Hay. U.S. Patents 3,306,874 and 3,306,875; Stamatoff U.S. Patents 3,256,358 and 3,257,357; Wieden et al, U.S. Patent 3,442,885; obyashi et al U.S.
• Patent 3,445,880 Nakashio et al U.S. Patents 3,573,257 and 3,658,945; Haaf U.S. Patent 3,737,479, and White U.S. Patent 4,165,422, which is the most relevant of the group- (see. example thereof) .
• Commercial interest has centered about the polymer which is prepared from 2,6-xylenol which has the theoretical . .structure:
• the resulting polymer is substantially composed of units having the theoretical structure:
• the polymers are usually prepared by the batch method, by slowly pumping a charge of a solution of the desired polymerizable phenol or mixture of polymerizable phenols into a cylindrical reaction vessel which contains a solution of the desired catalyst and an oxygen supply tube extending to the bottom of the vessel.
• the catalysts and phenols usually have, limited solubility, and consequently the solvents which are used are usually the low molecular weight hydrocarbons or halocarbons or mixtures of these with alcohols, esters or ketones, all of-which are voltaile.
• the reactor is provided with a jacket and interior cooling coils through which cold water or brine is circulated as required to prevent the temperature of the reaction mixture from rising above any of these danger points, generally taken to be 60°C.
• the polymer is recovered, the solvents are separated, and the catalyst is renewed. Details of the process and a variety of suitable catalysts and starting phenols are disclosed in the patents set forth above, which are hereby incorporated by reference in this specification.
• a fluid solution of a polymerizable phenol in an inert volatile organic liquid at about room temperature is added as a 25. stream to a solution of a catalyst in a similar liquid, and oxygen is admitted as a stream into the reaction _ mixture at such a rate that oxidation of the phenolic hydroxy groups to ether groups takes place at a substantially constant rate during admixxion of the 30 phenolic component to the reactor.
• oxygen is admitted as a stream into the reaction _ mixture at such a rate that oxidation of the phenolic hydroxy groups to ether groups takes place at a substantially constant rate during admixxion of the 30 phenolic component to the reactor.
• the reaction mixture is intensively agitated so as to disperse the 35 oxygen in small bubble or foam state throughout the reaction mixture to ensure that substantially all of the oxygen, at least during the initial phase of the polymerization, reacts with the phenol so as to cut losses of oxygen to a minimum.
• air can be economically employed as the source of oxygen.
• the precise rate at which the oxygen is admitted to the reaction mixture depends on a number of independent variables, for example the molecular weight of the phenol (or mixture of phenols, hereinafter for convenience termed "the phenol") , the rate at which the phenol is supplied to the reactor, the. temperature of the reaction mixture, the efficiency of the catalyst which is employed, and the ratio of the volume of the reactor to the area of its cooled surface.
• a suitable oxygen admission rate in any instance can be readily found by a series of trials, the preferred rate being generally that which maintains the temperature at a level just below the decomposition point of the catalyst (usually 25°C.
• the temperature at which side reactions become significant or the temperature at which the solvent volatilizes to more than a negligible extent, whichever is the lower.
• the rate of admission of oxygen is less than that which is stoichiometrically equivalent to the phenolic hydroxy groups.
• the phenol component is "starved" for oxygen during this phase of the reaction.
• the quantity of oxygen admitted to the reaction is controlled so as to keep substantially constant the rate per unit of ti e at which the hydroxy groups are oxidized to ether groups.
• the rate is such that the temperature of the reaction mixture is less than 50°C. when l/2_of the phenol-solvent charge has been added to the reaction mixture.
• the aforesaid oxidation reaction is not self-sustain ⁇ ing, and the heat which it releases is a direct function of the quantity of oxygen which has been reacted. Accordingly, it is advantageous to introduce pure or substantially pure oxygen in an excess for a brief period at the start of the reaction, so as to bring the reaction mixture to its optimum reaction temperature and so to bring this phase of the polymerization to a conclusion as quickly as possible.
• the product of this phase of the polymeri- zation is predominantly a mixture of low oligomers of the phenol (that is, low molecular weight prepolymers) including dimers, trimers and tetramers, plus a substantial proportion of the phenol in unreacted state.
• the foregoing means that the oxygen is introduced or:.injected into the reaction mixture at such a rate that between about 1/4 and 3/4 by weight of the added phenol (i.e. , the weight of phenol which has been added to the reaction mixture) is in the aforesaid low oligomeric state when between about 1/3 and 2/3 of the charge of the phenol has been added, that is, when the addition of the phenol to the reaction mixture is between about 1/3 and 2/3 complete.
• the rate of admixxion of oxygen is such that at least 1/2 of the weight of said added phenol is in low molecular weight oligomeric state when about 1/2 of the phenol-solvent charge has been added.
• the catalyst which is used to promote the oxidation reaction should be non-hydrolyzable since the polymeriza- tion reaction results in the formation of a considerable amount of water.
• the Hay catalysts (disclosed in the aforementioned patents) are preferred since they are very resistant to hydrolysis, are easily prepared, and possess good resistance to decomposition or deactivation under reaction conditions.
• These catalysts are complexes in a volatile inert solvent of a cuprous compound or cupric compound and one or more amines and a halogenide, preferably a bromide.
• the catalysts can contain a lower (C-. _g alkyl) secondary amine to improve the impact resistance of the polymer.
• any other non-hydrolyzable catalyst can be employed, for example, one of the highly reactive manganese salt (chloride, sulfate, etc.) - benzoin oxime catalysts wherein the benzoin oxime is present as ligand.
• the solvents referred to above can be any volatile organic liquid which is inert and which possesses the necessary solubility characteristics. Aromatics such as benzene and toluene are suitable, but it is preferable to have a substantial amount of a lower alkanol present such as methanol and/or ethanol to receive the water which is formed in the reaction.
• the process is at an end when a polymer has formed which has a softening point which,is sufficiently high to render it practically useful, for example 150°C. and preferably 200°C.
• the reaction is halted by switching the supply of oxygen (or air) to nitrogen followed by addition of trisodium ethylenediaminetetraacetate, after which the catalyst is separated, and the polymer recovered.
• the invention is thus an improvement in a batch- process for the manufacture of a polyphenylene ether resin by the catalytic oxidation polymerization of a phenol, wherein a fluid charge of a polymerizable phenol in an inert volatile organic solvent is added as a stream to a solution of a polymerization catalyst in a. voltaile organic solvent, and oxygen is introduced as a stream into the resulting mixture with agitation of the mixture to form a uniform dispersion of. the phenol, the catalyst and the oxygen, until a resin has formed which has a softening point in excess of 150°C.
• the improvement being introducing said oxygen into said mixture at rate that between about 1/4 and 3/4 by weight of said added phenol is in low oligomeric prepolymeric state when between about 1/3 and 2/3 of said charge of said phenol has been added.
• the invention includes the additional step .of increasing the length of the addition time for the introduction of the phenol-solvent solution to said mixture, thereby enabling the rate of oxygen introduction to be decreased without production of additional diphenoquinone by ⁇ product.
• EXAMPLE 1 The following illustrates the process of the present invention wherein a Hay-type catalyst is used and wherein the oxygen is injected at such rate that about 1/2 of the added phenol is in low oligomeric prepolymer state when about 1/3 of the phenol-solvent charge has been added to the reaction mixture.
• oxygen inlet tube Into a 2.5-gallon water-jacketed stainless steel reactor equipped with paddle stirrer, oxygen inlet tube
• interior cooling coils and viscosity monitor " (a pressure gauge mounted on a sampling loop through which the reaction mixture is constantly circulated) are charged at room temperature 3.3 5 liters of toluene as diluent, 62 ml. of laboratory catalyst stock solution (made by adding 23.1 ml. of bromine slowly to a chilled solution of 6.21 g. of cuprous oxide and 86.8 g. of 2,6-xylenol in methanol and diluting the mixture to 0.5 liter with methanol), 679. l. of 95% 10 methanol, 1.85 g. of N,N'-di-t-butylethylenediamine, 21.8 g.
• 2,6-xylenol in 1.33 liters of toluene is pumped into the mixture in 56 minutes.
• the reaction temperature rises from 18°C. to 24°C. in five minutes and from 24°C. to
• reaction temperature is maintained at 40°C. by admission of cooling
• tetramethyldiphenoquinone is formed and the amount which is present is determined at intervals by removing, during the first part of the
• the weight of tetramethyldiphenoquinone in the reaction mixture is 1.07% of the weight of xylenol added, and the softening point of the polyphenylene ether product, after injection molding, is over 150°C.
• the following illustrates the controlled addition of the phenol component and of the oxygen to prevent " the rate of formation of heat in the reactor from rising above a safe level.
• Example 20 The procedure of Example 1 is repeated, except that the rates at which the phenolic component and the oxygen are added are decreased after the temperature of the reaction mixture has risen to the desired level. Initially,
• the rate of flow of the oxygen is then decreased to 3.0 3 . 30 ft. per..hour, and the rate of addition of the xylenol is decreased so that the remaining 800 g. of the xylenol is added in 48 minutes.
• the temperature of the reaction is controlled at 40°C.
• the polymeriza ⁇ tion is terminated 86 minutes after the start of the 5 addition of the xylenol ' (and therefore 28 minutes after completion of the addition of the xylenol) .
• the polymeriza ⁇ tion is terminated 86 minutes after the start of the 5 addition of the xylenol ' (and therefore 28 minutes after completion of the addition of the xylenol) .
• RE is isolated by coagulation with methanol, collected by filtration and dried in vacuo at 70°C.-80°C.
• the intrinsic viscosity of the polymer is 0.56 dl./g.; the weight of tetramethyldiphenoquinone in the reaction mixture 5 on-..conclusion of the reaction is 0.95% of the weight of the xylenol shich was added.
• EXAMPLE 3 The following illustrates the polymerization of a polymerizable phenol under highly oxygen-starved conditions
• Example 10 so that advancement of the phenol beyond the low molecular weight oligomeric stage is slight during. the first half of the addition of the phenol, with consequent decrease in the amount of heat which is formed in the reaction mixture.
• the procedure of Example 1 is repeated except
• Example 1 The procedure of Example 1 is repeated except that the xylenol is added over 30 minutes and air at room
• OM reaction temperature increases from 23°C to- 40°C in 63 minutes.
• the reaction is terminated.181 minutes after the start of addition of the xylenol.
• the weight of tetramethyldiphenoquinone in the reaction mixture is
• the intrinsic viscosity of the isolated polymer is 0.57 dl./g.
• the weight of tetramethyldiphenoquinone in the :_ reaction mixture is 0.80% of the weight of the xylenol added.
• the intrinsic viscosity of the isolated polymer is 0.68 dl./g.
• Example . 1 The procedure of Example . 1 is repeated except that
• the weight of tetramethyldiphenoquinone is the reaction mixture is 1.5% of the weight of the xylenol which was added.
• the polymer After isolation, the polymer has an intrinsic viscosity of 0.54 dl./g.

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• 1982
  • 1982-05-04 WO PCT/US1982/000577 patent/WO1983003833A1/fr not_active Application Discontinuation
  • 1982-05-04 AU AU85257/82A patent/AU8525782A/en not_active Abandoned
  • 1982-05-04 JP JP50179082A patent/JPS59500721A/ja active Pending
  • 1982-05-04 EP EP19820901775 patent/EP0107653A4/fr not_active Withdrawn

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