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
  • C08G63/00—Macromolecular compounds obtained by reactions forming a carboxylic ester link in the main chain of the macromolecule
  • C08G63/78—Preparation processes
  • C08G63/82—Preparation processes characterised by the catalyst used
  • C08G63/83—Alkali metals, alkaline earth metals, beryllium, magnesium, copper, silver, gold, zinc, cadmium, mercury, manganese, or compounds thereof
• • 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
  • C08G63/00—Macromolecular compounds obtained by reactions forming a carboxylic ester link in the main chain of the macromolecule
  • C08G63/02—Polyesters derived from hydroxycarboxylic acids or from polycarboxylic acids and polyhydroxy compounds
  • C08G63/12—Polyesters derived from hydroxycarboxylic acids or from polycarboxylic acids and polyhydroxy compounds derived from polycarboxylic acids and polyhydroxy compounds
  • C08G63/16—Dicarboxylic acids and dihydroxy compounds
  • C08G63/18—Dicarboxylic acids and dihydroxy compounds the acids or hydroxy compounds containing carbocyclic rings
  • C08G63/19—Hydroxy compounds containing aromatic rings

Definitions

• the present invention relates to a melt polymerization process for preparing resorcinol phthalate polyesters, wherein an ester interchange reaction takes place and to the product prepared therefrom.
• polyesters have been prepared by a variety of methods including ester interchange, direct esterification, interfacial polymerization and acidolysis (see U. S. Patent No. 4,011,199).
• polyesters of aliphatic and cycloaliphatic diols have viscosities that make these polyesters particularily suitable for commercial preparation using an ester interchange process.
• Polyesters prepared using aromatic diols typically have such high melt viscosities that ester interchange cannot be used.
• One particular method of achieving an ester interchange reaction is by a melt polymerization technique. This procedure is advantageous because it permits utilization of the free acid as opposed to the more expensive acid chloride required by certain other techniques. Further advantages of this technique lie in the ability to dispense with the solvent recovery and acid neutrilization procedures which are necessary when the acid chloride route is used.
• melt polymerization procedures of the prior ,art yield a commercially unacceptable product when applied to the preparation of a resorcinol phthalate polyester.
• resorcinol phthalate polyesters in general are known as illustrated by W. Eareckson, Interfacial Poly Condensation X Poly Phenyl Esters, 40 J. Pol. Sci. 399-406 (1959); U. S. Patent Nos. 3,160,602; 2,595,343; and 2,035,578; and British Patent No. 863,704.
• the discussion of resorcinol-phthalate polyesters in the prior art has typically centered on methods of making polyesters in general. Consequently, the description of specific resorcinol phthalate polyesters and the properties associated therewith have been of limited scope.
• wholly aromatic polyesters may be prepared by an ester interchange reaction as illustrated by U. S. Patent Nos. 3,160,604; 3,036,992; and 2,595,343.
• alkali and alkaline earth metal acetate catalysts are especially suited for the preparation of a resorcinol phthalate polyester by the melt polymerization process described herein and that most of the conventional ester interchange catalysts such as the representative catalysts described above are unacceptable for this purpose.
• an object of the present invention to provide a process for the preparation of a melt processable resorcinol phthalate polyester by the melt polymerization of resorcinol diacetate and a phthalic acid or mixtures thereof.
• a process for preparing a melt processable resorcinol phthalate polyester which comprises (a) reacting resorcinol diacetate with a phthalic acid selected from the group consisting of isophthalic acid and a mixture of isophthalic and terephthalic acid wherein the terephthalic acid is present therein in an amount not greater than about 30 mole percent of the mixture, which reaction is conducted in the presence of an alkali or alkaline earth metal acetate catalyst or a mixture of such catalysts at a temperature of 180 to 240°C for a period sufficient to form a non-volatile pre-polymer; and (b) polymerizing the non-volatile pre-polymer of step (a) at a temperature above the melting point of both the pre-polymer and the resulting polymerized product in the presence of an alkali or alkaline earth metal acetate catalyst or a mixture of such catalysts to yield a polyester having an inherent visco
• the resorcinol diacetate is prepared by reacting resorcinol and an acetylating agent by heating said compounds to a temperature of 100 to 130°C and in a manner sufficient to yield resorcinol diacetate; and purifying the resulting resorcinol diacetate , preferably by vacuum distillation to the extent sufficient to obtain 99.5% resorcinol diacetate.
• a melt processable resorcinol phthalate polyester which comprises the reaction product of resorcinol diacetate and a mixture of at least 70, eg. 95 to 80 mole percent isophthalic acid and correspondingly not more than 30, eg. from 5 to 20, mole percent by weight terephthalic acid.
• terephthalic acid When terephthalic acid is present in an amount greater than about 30 mole percent the melting point of the resulting polyester is greater than the temperature at which significant degradation occurs and it is not feasible to prepare the polymer by a melt polymerization procedure.
• a resorcinol phthalate polyester having a terephthalate content greater than about 30% is not melt processable.
• a melt processable resorcinol phthalate polyester is one which can be extruded (e.g., injection molded) at temperatures of from 250 to 320 0 C at a pressure of 5,000 to 25,000 psi.
• Properties of the resorcinol phthalate polymer such as tensile strength, flexural strength, modulus, glass transition temperature (Tg) and heat distortion temperature may be varied by altering the isophthalic- terephthalic acid isomer ratio within the described ranges.
• the presence in limited amounts of the terephthalate moiety in the resulting polyester increases the strength and use temperature thereof while lowering the melting point and thereby improving melt processability.
• isophthalic and terephthalic acid may be present in the reaction mixture in any amounts within the defined limits in any amounts within the defined limits it is preferred that the isophthalic acid be present in amounts which can vary from 100 to 80 mole percent, preferably from 95 to 80 mole percent, and most preferably from 90 to 85, or 90 to 80 mole percent (e.g., 90 mole percent) by weight of the total mixture, and correspondingly the terephthalic acid can be present in amounts which can vary from 0 to 20 mole percent, preferably from 5 to 20 mole percent, and most preferably from 10 to 15 mole percent (e.g., 10 mole percent) by weight of the total mixture.
• the resorcinol diacetate utilized as a reactant in the melt polymerization process should not contain impurities which would adversely affect the resulting polymer product.
• the melt polymerization reaction is generally conducted with the reactants present in amounts sufficient to fully transesterify the resorcinol diacetate. Generally, substantially stoichiometric amounts of each reactant are employed; typical molar amounts of from 1:0.9:0.1 to about 1:0.8:0.2 of resorcinol diacetate, isophthalic acid, and terephthalic acid, respectively, are utilized.
• the melt polymerization reaction of the present invention has been found to be dependent on the utilization of certain specified catalysts and temperatures.
• polytransesterification catalysts such as Sb 2 0 3 , tetra alkyl titanates (e.g., tetrabutyl titanate), dialkyl tin oxides (e.g., dibutyl tin oxide), diaryl tin oxide, titanium dioxide, alkoxy titanium silicates, titanium alkoxides, and the gaseous acid catalysts such as Lewis acids, hydrogen halides (e.g., HCl) are unsuitable for the purposes of the presently claimed invention and yield only highly colored low molecular weight material.
• tetra alkyl titanates e.g., tetrabutyl titanate
• dialkyl tin oxides e.g., dibutyl tin oxide
• diaryl tin oxide e.g., titanium dioxide
• alkoxy titanium silicates e.g., titanium alkoxides
• gaseous acid catalysts such as Lewis acids, hydrogen halides (e.g., HC
• the relative reactivity of the catalysts varies depending on whether it is utilized in the first stage of pre-polymer formation or the second stage of polymerization, i.e., melt polymerization.
• the preferred metals utilized to provide the metal acetate catalysts include in order of descending reactivity, sodium, potassium, lithium and calcium while the preferred metal of the second stage includes in order of descending reactivity potassium, calcium, lithium and sodium.
• the most preferred catalyst for both stages is a mixture of sodium acetate and potassium acetate wherein the components of said mixture are present at a molar ratio of about 1:1.
• any effective amount of catalyst may be utilized in either the first (i.e., pre-polymer forming) stage or second (i.e., melt polymerization) stage, it is preferred that such amount constitute in the first stage from 1.0 to 0.1%, most preferably about 0.7% by weight based on the total monomer weight of resorcinol diacetate, and in the second stage from 1.0 to 0.1% , and most preferably about 0.5% by weight of the total weight of the non-volatile pre-polymer.
• Utilization of the above described metal acetate catalyst enables two step polymerization times of about 3 to about 12 hours, preferably from about 3 to about 8 hours, and most preferably from about 3 to about 4 hours to be obtained in accordance with the present invention.
• the short polymerization times obtainable by the use of the metal acetate catalyst minimizes the rearrangement of the polyester molecule chains and consequently a high molecular weight melt processable polymer can be obtained.
• the first stage is conducted at temperatures below the boiling point of the resorcinol diacetate to yield a non-volatile pre-polymer. It is not feasible to directly melt polymerize the above reactants since resorcinol diacetate exists as a liquid at room temperature and is volatilized at the temperature required for melt polymerization. To overcome this difficulty, the resorcinol diacetate monomer is reacted at low temperatures to an extent sufficient to condense at least one of the acetate groups present thereon with a carboxyl group of the phthalic acid to form a pre-polymer comprising dimers trimers and the like.
• the pre-polymer may be characterized as being non-volatile, in that it degrades under the influence of elevated temperatures before it vaporizes into the gaseous state.
• any temperature below the boiling point of the resorcinol diacetate which is sufficient to achieve the desired reaction may be utilized, it is preferred that such temperature constitute from 180 to 240°C, preferably from 200 to 240°C, and most preferably from 220 to 240°C.
• the pre-polymer forming reaction it is possible to monitor the evolution of acetic acid. This can be accomplished by condensing the vapor as it is removed from the reaction vessel and measuring the weight or volume. The reaction is considered complete when about 90% by weight of the theoretical amount is collected.
• the pre-polymer forming reaction can be conducted to provide a pre-polymer having an inherent viscosity (I. V.) measured in a 0.8% solution in pentafluorophenol of from 0.05 to 0.2 (e.g., 0.1).
• I. V. inherent viscosity
• Typical reaction times sufficient to obtain the non-volatile pre-polymer can vary from 1 to 4 hours, preferably from 1 to 3 hours, and most preferably from 1 to 2 hours.
• the pressure at which the pre-polymer forming reaction can be conducted is typically atmospheric.
• the pre-polymer forming reaction is desireably conducted under an inert atmosphere such as nitrogen.
• a heat transfer medium in the preparation of the non-volatile pre-polymer.
• the heat transfer medium should be capable of substantially dissolving the reactants and resulting pre-polymer and refluxing under the temperatures employed to prepare a pre-polymer. It should also be incapable of undergoing reaction with the reactants.
• the heat transfer medium serves to conduct heat uniformly to the reactants while at the same time washes the sides of the reaction vessel thereby keeping the reactants in contact with each other.
• Suitable heat transfer mediums include inert solvents having a boiling point of not lower than about 250°C.
• Representative heat transfer mediums include diphenyl ether, terphenyls and mixtures thereof such as those composed of meta and para isomers commercially available from Monsanto Chemical Company under the trademark Thermim 1 (e.g., Therminol 88, 77, or 66) chlorinated diphenyls, benzophenone, and chlorinated diphenyl ether.
• Thermim 1 e.g., Therminol 88, 77, or 66
• a preferred heat transfer medium is diphenyl ether.
• the heat transfer medium e.g., diphenyl ether
• the heat transfer medium is typically present at an amount which can vary from 10 to 50% by weight of the combined weight of reactants and heat transfer medium.
• a heat transfer medium is utilized, it is generally removed from the reaction vessel prior to commencing the second stage of polymerization by any means known to those skilled in the art, such as by distillation.
• a heat transfer medium having a boiling point above the temperatures employed in the second stage polymerization reaction may remain present during polymerization although its presence does not contribute substantially to the melt polymerization procedure.
• the non-volatile pre-polymer prepared in accordance with the procedure described above is then polymerized at a temperature above the melting point of both the pre-polymer and the resulting polymerized product and in the presence of the above-described metal catalyst to yield a resorcinol phthalate polyester.
• the temperature is from 240 to 300°C, preferably from 260 to 290°C, and most preferably from 270 to 280°C.
• the melt polymerization reaction is conducted at the above-described temperatures for a period of 1 to 8 hours, preferably from 2 to 6 hours, and most preferably from 2 to 4 hours and under a reduced pressure of 0.4 to 2 mm Hg, preferably from 0.1 to 1 mm Hg, and most preferably from 0.1 to 0.3 mm Hg.
• melt polymerization reaction it is also preferred to conduct the melt polymerization reaction under an inert atmosphere such as nitrogen or argon.
• the melt polymerization reaction is conducted so as to obtain a resorcinol phthalate polyester having an inherent viscosity (I.V.) of at least 0.4, preferably from 0.4 to 1.5, and most preferably from 0.5 to 1.0 (e.g., 0.5).
• I.V. inherent viscosity
• the I.V. is determined by measurement of the relative viscosity of a 0.1% solution of the polymer at 25°C in a suitable solvent, such as pentafluorophenol.
• the viscosity of the polymer solution is measured relative to that of the solvent alone and the inherent viscosity (I.V.) is determined from the following equation: In the above formula, V 2 is the efflux time of the solution, V 1 is the efflux time of the solvent, and C is the concentration expressed in grams of polymer per 100 ml. of solution.
• inherent viscosity is monotonically related to the molecular weight of the polymer.
• Another aspect of the present invention is directed to a process for preparing a melt processable resorcinol phthalate polyester from resorcinol and acetic anhydride or other suitable acetylating agent. It has been found that it is not feasible to react resorcinol and an acetylating agent under elevated temperature and utilize the resulting resorcinol diacetate product directly in the preparation of resorcinol phthalate polyester. This results from the fact that resorcinol diacetate synthesis is accompanied by the formation of several undesirable side products which if present during resorcinol phthalate polyester synthesis will yield a dark brown low molecular weight polymer which is not melt processable.
• the side products are believed to be induced by Fries rearrangements and/or acylation of the active resorcinol ring.
• the undesirable side products must, therefore, be removed from the synthesized resorcinol diacetate prior to commencing the synthesis of a resorcinol phthalate polyester from a resorcinol diacetate.
• resorcinol is reacted with a suitable acetylating agent.
• Suitable acetylating agents include acetic anhydride and acetyl halides such as acetyl bromide and preferably acetyl chloride.
• the acetylating reaction is conducted at temperatures below the boiling point of the acetylating agent and can typically range from 80 to 140°C, preferably from 100 to 130°C (e.g., 120°C) and in a manner sufficient to yield resorcinol diacetate. Temperatures in excess of the boiling point of the acetylating agent (e.g., 138 0 C for acetic anhydride) should not be utilized to avoid loss of the acetylating agent.
• the reactants are present at substantially stoichiometric molar ratio of about 1:2 of resorcinol and acetylating agent, respectively, although an excess, i.e., up to 50 mole % of the acetylating agent may be utilized to increase the reaction rate and then recycled.
• the resorcinol diacetate is then purified to eliminate the undesirable side products, such as, by vacuum distillation or low temperature recrystill- ization.
• the purification procedure is conducted to the extent sufficient to obtain a purity of about 99.5% and to eliminate any monoacetate, and products resulting from Fries rearrangement or ring acylation which produce a chain stopping action if present during the pre-polymer formation and particularly during the melt polymerization step.
• the only impurity whose presence is acceptable in trace amounts (i.e., less than 0.5%) is the dimerization product of resorcinol.
• the purified resorcinol diacetate is then utilized in accordance with the processess described above.
• one or more solid fillers or reinforcing agents optionally may be incorporated in the same via a melt admixture - technique to form a filled and/or reinforced injection molding compound.
• Such fillers and/or reinforcing agents may be included in a total concentration of about 0 to 40% by weight of the resulting molding compound.
• Representative fibers which may serve as reinforcing media include glass fibers, asbestos, graphitic carbon fibers, amorphous carbon fibers, synthetic polymeric fibers, aluminium fibres, aluminium silicate fibers, oxide of aluminium fibres, titanium fibers, magnesium fibers, rock wool fibers, steel fibers, tungsten fibers, cotton wool, and wool cellulose fibers. If desired the fibrous reinforcement may be preliminarily treated to improve its adhesion ability to the resorcinol phthalate polyester which ultimately serves as a continuous matrix phase.
• Representative filler materials include calcium silicate, silica, clays, talc, mica, polytetrafluoroethylene, graphite, alumina trihydrate, sodium aluminium carbonate and barium ferrite. Colorants optionally may be included.
• Molded shaped articles formed from the resorcinol phthalate polyester of the present invention generally exhibit a superior tensile strength, flex strength, and impact strength. Also, the appearance of the resulting molded articles being commonly clear and exhibiting a light yellow to amber color and an attractive smooth surface.
• the diphenyl ether solvent is not required for the reaction but is used for convenience to wash the sides of the vessel during the early stages of the condensation.
• the flask is fitted with a nitrogen inlet , Servodyne TM mechanical stirrer with RPM and torque read outs, condenser, fifty ml. graduated receiver and vacuum adaptor.
• the flask is purged with dry, oxygen free nitrogen and brought to 240°C over 0.5 hr. with stirring.
• the reaction is held at 240°C for 3 hr. while a theoretical amount of acetic acid is collected.
• vaccum is applied to remove the diphenyl ether, and the reaction temperature is brought to 280°C.
• the mixture is held at 280°C and 1.0 mm Hg pressure for three hours and the increase in viscosity is monitored by observing the stirring torque.
• the reaction is then cooled under nitrogen, the flask broken and polymer ground to approximately 5 mesh.
• Example 2 The same general procedure outlined in Example 1 is repeated with the exception that identity of the catalyst and/or reaction temperatures are varied.
• the catalyst and reaction conditions are summarized in Tables IA and IB.
• a 6 lb. resorcinol phthalate sample is prepared in accordance with the procedure outlined in Example 1 utilizing a sodium acetate catalyst with the exception that a longer reaction time for the second stage is utilized (i.e., 10 hrs. under vacuum in melt).
• the resulting product is pelletized by a Warner-Pfleider ZSK twin screw extruder, dried and injection molded. Molding conditions and polymer physical properties are summarized in Table II.
• the resulting product is purified by vacuum distillation under a pressure of about 10 mm Hg.
• the yield of purified resorcinol diacetate is about 85 to 90% by weight.
• the resulting purified resorcinol diacetate is reacted with isophthalic and terephthalic acid in accordance with the procedure outlined in Example 1.
• the resulting polymer possesses substantially the same physical and chemical properties as the polymer of Example 1.
• a resorcinol phthalate polyester is prepared in accordance with the procedure outlined in Example 1 except that 19.9 gm (0.12 mole) isophthalic acid, and 13.3 gm (0.08 mole) terephthalic acid are reacted with 39.4 gm of resorcinol diacetate. This corresponds to a molar ratio of isophthalic acid to terephthalic acid of 60:40.
• the pre-polymer solidifies at 240°C and although it melts at temperatures of about 300°C or higher the temperature must be increased to about or above the degradation temperature of the polymer to obtain a melt viscosity suitable to achieve successful melt polymerization.
• Example 6 is repeated with the exception that the resulting resorcinol diacetate is not purified prior to forming the resorcinol phthalate polyester.
• the resulting impure resorcinol diacetate when attempted to be melt polymerized in accordance with Example 1 does not yield a polymer which gradually increases to the desired molecular weight. Instead, the presence of the impurities changes the stoichiometry of the reaction thereby prohibiting formation of a high molecular weight polymer.
• the resulting product is dark amber, brittle, glossy and has a low molecular weight which is insufficient for use in typical injection molding techniques.
• resorcinol phthalate polyesters of the type described herein have a high char, low flammability and good injection molding properties, i.e. they are easily melt processable.
• this polymer to form a char upon combustion contributes to the unexpectedly low level of flammability by retaining the less oxidizable aromatic moieties in the bulk phase via cross linking and thereby removes them from involvement in the combustion as combustible gaseous fuel.
• the carbonaceous char also acts as a thermal (e.g., heat sink) and gas diffusion barrier thereby inducing a cooling effect at the polymer surface while simultaneously disrupting diffusion of oxygen to the polymer surface and small combustible molecules to the flame front.
• the resorcinol phthalate polyester of the present invention can be readily melt processed to form a variety of shaped articles, e.g. molded three dimensional articles, fibers, or films.
• the polyester of the present invention is particularly suited for molding applications and may be molded via standard injection molding techniques commonly utilized when forming molded articles unlike resorcinol phthalates having an acid isomer ratio outside the claimed ranges. Fibers or films may be melt extruded.

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• Organic Chemistry (AREA)
• Polyesters Or Polycarbonates (AREA)

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• 1977
  • 1977-08-08 US US05/822,579 patent/US4127560A/en not_active Expired - Lifetime
• 1978
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