CA1248682A - Process for the isolation of thermoplastic polycarbonates from their solutions - Google Patents
Process for the isolation of thermoplastic polycarbonates from their solutionsInfo
- Publication number
- CA1248682A CA1248682A CA000488659A CA488659A CA1248682A CA 1248682 A CA1248682 A CA 1248682A CA 000488659 A CA000488659 A CA 000488659A CA 488659 A CA488659 A CA 488659A CA 1248682 A CA1248682 A CA 1248682A
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- CA
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- Prior art keywords
- polycarbonate
- benzene
- mixture
- alkylbenzene
- process according
- Prior art date
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Classifications
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- 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
- C08G64/00—Macromolecular compounds obtained by reactions forming a carbonic ester link in the main chain of the macromolecule
- C08G64/40—Post-polymerisation treatment
Abstract
Process for the isolation of thermoplastic polycarbonates from their solutions A b s t r a c t The present invention relates to the isolation of thermoplastic polycarbonates from their solutions by treating the organic solutions, obtained in the phase boundary processes, of the thermoplastic polycarbonates with vapours of benzene or alkylbenzenes.
Description
L~
Process for the isolation of thermoplastic polycarbonates from th~ir solutions In the known preparat;on of thermoplastic aromatic polycarbonates by the two-phase boundary pro-cess~ the polycarbonates are obtained in the organic phase, from which they must be isolated after this has been separated off and purified. (See, for example, H. Schnell, "Chemistry and Physics of Polycarbonates", 1964, Interscience Publishers, New York, London, Sydney, pages 41 to 44).
For the polycarbonate based on bisphenol Ao which is industrially the most important polycarbonate, there are the following possibilities: one possibili~y for the isolation comprises precipitation of the polycarbonate from its solutions by non-solvent~ (see, for example, U.S. Patents Nos. 3,264,262, 3,26l~263 and 3~264~264).
Toluene, inter alia, is mentioned here as a non solvent.
The precipitation method has the disadvantage ~hat the po~der obtained must be dried and made up into free-flowing granules, which can cause diff;culties if precipitation has not been carried out properly. The recovery of the solvent for the polycarbonate and ~he loss of polycarbonate due to non-quantitative precipi-~ation are ~echnological disadvantages.
An isolation method ~hich is differen~ in prin-ciple leads directly to a polycarbonate melt via evapora-tion of the solvent (see9 for example, U.S. Patent- 3,022,271, DE-OS (German Published Specification) 1,4P4,984 and DE-AS (German Published Specification) 1,209,741). There is the danger here of damage to the polycarbonate, since the last residues of solvent are removed at relatively high temperatures.
The solvent content of polycarbonate solutions can also be reduced by means of water (see U.S. Patent 3,505~73).
It is also possible to add monochlorobenzene or Le A 22 921-US
, ~
~2~
polyhydric alcohols or aqueous solutions of these poly-hydric alcohols to the polycarbonates in amounts of 0.1 to 10% by weight beFore extrusion thereof to remove solvent residues from polycarbonates ~see DE-OS ~German Published SpeciFication~ 2,917,3~6).
Another method for isolating polycarbonate com-prises crystallisation of poLycarbonates from their solu-t;ons, wh;ch is promoted by concentrating the solutions at elevated temperature and/or reduced pressure, or adding non-solvents tsee U.S. Patent 3,112,292, ;n par-ticular column 3, paragraph 3). Solvents for the poLy-carbonate which are recommended here are also, inter alia, benzene, toluene and xylene, although this does not apply to polycarbonates based on bisphenol A, but, for exarple, to polycarbonates from chlorinated bisphenols (see Example 4 of U.S. Patent 3,112,2~2).
S;milar processes are described in the Japanese publications No. 78-137,297 and No. 78~137~29R oF Mit-subishi Gas, wherein polycarbonate solutions are mod;fied by adding non-solvents so that they solidiFy. Needless to say, benzene, toluene and xylene, inter alia, are mentioned as non-solvents~ toluene being effective 3S a particularly suitable non-solvent.
bE-OS (German Published Specific3tion) 2,825~857 describes a particular process for the preparation of polycarbonate from polycarbonate solutions, wherein the solvent is evaporated and the polycarbonate obtained is powdered ;mmediately. Su;table solvents for polycarbon-ates are chlorinated, aliphat;c hydrocarbons and pyridine.
3~ Aromatic hydrocarbons, such as benzene, chlorobenzene and toluene, can be admixed in order to facilitate po~dering oF the polycarbonate. Toluene is co-used in the examples~
A further development of the process oF U.S.
Patent 3~112,292 is described in U.S. Patent 3,322~724, ~here solid polycarbonates instead of non-solvents are added to the polycarbonate solutions in order to cause Le A 22 921 .__ crystallisation of the polycarbonate. Solvents for the polycarbonate which are mentioned are, inter a~ia, ben-zene~ toluene and xylene, in addition to others, but these again are not suitable for polycarbonates based on bisphenol A (in this context, see, for example, the embodiment examples of U.S. Patent Specifica~ion .3,322,~24).
In DE-AS (German Published Specification) 1,100,949, pulverulent polycarbonates are prepared by swelling already isolated polycarbonates with a small amount of organic solvents. Organic solvents mentioned here are benzene, toluene and xylene, inter alia, but these are again presented as b;sphenol A polycarbonate non~solvents and thus convert the bisphenol A polycar-bonate only into a powder in accordance with the processof DE-AS (German Published Specification) 1,100,949.
Another process for isolating polycarbona~es fro~
their solutions comprises tre3ting the polycarbonate solu-tions ~ith steam, ~hich virtually completeLy vaporises the solvent (seeO for e~ampleO U.S. Patent 3,427,370 and European Published Application 0,003,996).
Finally, there is also the possibility of prepar^
ing ~he polycarbonate immediately in solid form if the reaction is carried out ~ith phosgene in the presence of aromatic, optionally chlorinated hydrocarbons, surface-active substances and aqueous alkali solution tsee the Japanese Patent Application of the Kunoshima Chem. Ind.
16907t59 of Z5.5.1959, published on 16.12.1966, No.
2147Z/66)~
30 ~ All these isolation methods still have this or that technological disadvantage, so that there is still a certain need for improvement in the process for isolat-ing polycarbonates based on bisphenol A whilst retaining the good product quality.
The present invention thus relates to a process for the isolation of thermoplastic polycarbonates based Le A 22 921 on bisphenol A from their solu-tions r which is charac-terized in -tha-t the purified polycarbonate solu-tions, prepared in a known manner by the phase boundary process, in organic solven-ts, preferably in ali-phatic chlorinated hydrocarbons, are treated with vapours of benzene or alkylbenzenes, in which the thermoplastic polycarbonate based on bisphenol A is sparingly soluble or insoluble at room temperature and which also in each case have a higher boiling point than the solvent to be evaporated off from the polycarbonate solutions re-sulting from the phase boundary process, the treatment with -the va-pours being continued until the solvent to be evaporated off isevaporated off down to a residual content of less than 0.5% by weight, preferably of less than 0.1~ by weight, based on the total weight of the resulting polycarbonate/benzene or alkylbenzene mix-ture, and in that the polycarbonate is isolated as a melt rom the resulting mix-ture by evaporating off the benzene or alkylbenzene in known apparatuses, pressure being applied.
According to the present invention -there is provided a process for the isolation of a thermop].astic polycarbonate based on bisphenol A, which is prepared by the phase boundary process, from a solution containing an organic solvent comprising (i) continuously treating a solu-tion of said polycarbonate in said organic solvent with a vapor of at least one member selected from the group consis-ting of benzene and alkylbenzene, said member being characterized in that polycarbonate is sparingly soluble or insoluble -therein at room temperature and further in that its boiling point is lower than that of said organic solvent, until said organic solvent is evaporated off down to a residual content of less than 0.5% by weight based on the total weight of the mixture of said polycarbo-nate and said member and (ii) isolating said polycarbonate either as a melt from said mixture by evaporating off said member under pressure or by solidifying said mixture and removing said member by drying.
Examples of alkylbenzenes which are suitable according to the invention are toluene, ethylbenzene and the various xylenes.
Mixtures of benzene with alkylbenzenes are also suitable. Toluene is particularly preferred.
"In which the thermoplastic polycarbonate is sparingly soluble or insoluble at room temperature" in -the context of the process according to the invention means that the thermoplastic polycarbonate based on bisphenol A has a solubility of less than 3%
by weight, based on the weight o:E benzene or alkylbenzene, at room temperature (20C).
"Have a higher boiling point" in the context of the pro-cess according to the invention means that the benzene or the par-ticular alkylbenzene to be selected must have a boiling point under normal pressure at leas-t 20C higher than -the particular organic solvent employed ,-- 4a -~2L~
in the phase boundary process.
The polycarbonate/aromatic mixtures obtained according to the invention can be ~orked up completely by evaporation at high temperatures without damage to ~he polycarbonate or the apparatus. The resulting poly-carbonates are distinguished by their light colour.
Examples of suitable apparatuses for the process according to the invention are columns, bubble columns or cascades of stirred containers.
The process according to the invention is parti-cularly advantageously carried out continuously in a column in ~hich the vaPoUr of the aromatic is blown in from the bottom and the polycarbonate solution resulting from the phase boundary process is introdured at the top.
The polycarbonate/benzene or alkylben~ene mixture is drawn off continuously from the bottom of the column.
The particular organic solvent used in the phase bound-ary process is continuously taken off in vapour form at the top of the column. The temperature programme in the column can be derived from the phas~ equilibrium curve of the particular organic solvent in the phase boundary process and the particular aromatic used. The tempera-ture range for the polycarbonate solution to be fed in can be between 20C and 100C, an~ that of the vapour Z5 of the aromatic can be between 80C and 200C.
The particular temperature level can be modified by applying different increased pressures~
Slight increased pressures are advantageously chosen~ so that the operating conditions in the plants are not close to the limit of the unstable region of the mixtures.
In the case of polycarbonate based on bisphenol A
~here methylene chloride is replaced by toLuene, pres-sures of 1 to 5 bar absolute are sufficient. The tempera-tures are about 41-1oooc at the inlet point for the polycarbonatelmethylene chloride solution and about 112-Le A 22 9~1 36~;~
195C at the ;nlet point for the toluene vapour. Pres-sures o~ 1.5 to 3 bar absolute are preferably established.
The concentrations of polycarbonate in the poly-carbonate solution to be fed in are between 3 and 30X, preferably bet~een 10 and 25%. They are usually hardly var ed by conversion by means of the aromatic vapour treatmen~ according to the invention into the polycarbon-ate/benzene or alkylbenzene mixtures ~ecause of the energy balance, the concentrations may drop slightly, rema;n the same or increase. If desired, there ;s the possibility of establishing higher polycarbonate concen-trations in the polycarbonate/benzene or alkylbenzene mixtures by supplying additional energy.
Since the polycarbonate is isolated via evapora-tion, the rPsulting vapour of the benzene or alkylbenzenecan be utilised directly for evaporating off the organic solvent used in the phase boundary process Thermoplastic polycarbonates based on bisphenol A ;n the context of the present invention are those ~ith Mw between 100~00 and 200,000~ preferably between 20~0ûO
and 8~,000 (Mw determined via the method of light scattering).
Polycarbonates based on bisphenol A are~ on the one hand, bisphenol A homopolycarbonate or those bis-phenol A coPolycarbonates which, in spite of co-using other d;functional components, have the abovementioned poor solubility at room temperature in benzene or in alkylbenzenes of less than 3X by weight.
Examples of other suitable difunctional co~pon-ents are diphenols other than bisphenol A, such as, forexample, 2,2-bis-t3,5-dibromo-4 hydroxyphenyl)-propaneO
Other difunctional components are, for example, also oligomers or polymers which carry two end grouPs which are capable of undergoing a build-up reaction under the cond;tions of polycarbonate synthes;s by the phase boundary process. Examples of such end groups are Le A 22 921 ~2'~
phenolic OH groups, chlorocarbonic acid ester groups and carboxylic acid chloride groups. Previously prepared oligomeric or polymeric blocks which already carry the reactive groups mentioned as a result of the nature of their preparation or in which such groups can be produced by a suitable after-trea~ment are, for example, poly-condensates based on aliphatic diols and saturated ali-phatic dicarboxylic acids, such as, for example, satura-ted aliphatic polyesters on a dimeric fatty acid basis (see, for example, U.S. Patent 4,430,492 or DE-OS ~German Published Specification~ 2,935,317) or also polysiloxanes (see, for example, U.S. Patents 3,419,634, 3,821,325 and 3~832~419)o The phase boundary process for the preparation of the thermoplastic aromatic polycarbonates to be iso-lated accord;ng to the invention is kno~n from the literature.
Especially suitable solvents for the phase boundary process which give polycarbonate solutions which are particularly suitable for the isola~ion process according to the invention are, in particular~ alipha~ic, halogenated hydrocarbons~ such as, for example~ CH2Cl2 or 1,1 dichloroethane. CH2Cl2 is especially suitable.
Known apparatuses for evaporating off the benzene or the alkylbenzenes are~ for example~ thin film evaporators and devolatilisation extrudersO
The polycarbonates isolated by the process accord ing to the invention are light-coloured products and are thus advantageously suitable for use in all the fields of application of polycarbonates.
They can be provided with the stabilisers, addi-tives and fillers known in the chemistry of thermoplastic polycarbonates in a known manner.
They can be shaped to the customary shaped poly-carbonate articles, such as semi-finished products, sheets, films and fibres, in a known manner.
~, Example 1 107 kg/hour of a 16.4X strength polycarbonate/
methylene chloride solution ~hich has been prepared by the phase boundary process are introduced at the top of a distillation column with a diameter of 200 mm and a height of 3,0no mm. 106 kg/hour of 'oluene vapour are passed in at the bottom. The column is operated under normal pressure. 41C ;s measured at the top of the column and 113C is measured at the bottom. The dis-tillate contains 0.43X of toluene; 250 ppm of methylenechloride are found in the polycarbonate/toluene mixture.
The polycarbonate/toluene mixture is pumped into a thin film evaporator operated under an increased pres-sure of 1.2 bar, and 65.5 kg/hour of toluene are dis-tilled off. The concentrated mixture is freed from thetoluene in a devolatilisation extruder.
A polycarbonate with the following characteris~
tic parameters is obtained:
relative viscosity ~ rel. 1.307 (0.5 9 in 100 ml of methylene chloride~
hydrolysable chlorine ~ppm~ < 2 phenolic OH [X~ 0.01 inorganic chlorine ~ppm] < 2 total chlorine ~ppm~ < 2 25 colour number* 0.05 * The colour number is an empirical relative characteris-tic figure. This is defined such that 0.05 units allow a visually perceptible graduation against the light at a test bar th;ckness of 4 mm.
Example 2 The example shows the extent to which polycarbon-ate is damaged by halogenohydrocarbons at high tempera-tures.
20X strength polycarbonate solutions with various solvents were heated at high temperatures in an autoclave with a sample of material 1.4571 for 4 hours~ The Le A 22 921 _ 9 solutions ~ere then taken out of the autoclave, the solvents were removed in a vacuum drying cabinet and the polycarbonate film was dissolved to give a 5X strength solution in pure methylene chloride~ in order to detect differences via the colour number of the solution.
S~lvent Temperature Hazen colour number Methylene chloride ~25C > 300 Chlorobenzene 3Z0C 80-90 Toluene 315C . 20-30 As an advantageous variant of the process accord-ing to the invention, it has also been found that the resulting polycarbonate/benzene or alkylben~ene mixtures give, by cooling, solidified mixtures from uhich the benzene or the alkylbenzenes can be removed virtually 1~ quantitatively by drying.
The present invention thus-also relates to a pro-cess for the isolation of thermoplastic polycarbonates . based on bisphenol A from their solutions, which is charac-terised in that the purified polycarbonate solutions, pre-pared in a known manner by the phase boundary process, inorganic solvents, preferably in aliphat;c chlorinated hydrocarbons~ are treated with vapours of benzene or alkylbenzenes, in which the thermoplast;c polycarbonate based on bisphenol A is sparingly soluble or insoluble at room te~perature and which also in each case have a higher boiling point than the solvent to be evaporated off from the polycarbonate solutions resulting from the phase boundary proress, the treatment with the vapours being continued until the solvent to be evaporated off is evaporated off do~n to a residual content of less than 0.5% by ~eight, preferably of less than 0.1X by weight, based on the total we;ght of the resulting polycarbonatet benzene or alkyLbenzene mixture, and in that the result-ing mixture is soLidified, preferably after concentration, 3~ and the benzene or alkylbenzene is ~hen removed by drying~
"Solidification" in the context of the process Le A 22 921 ___ æ
according to the invention means that the liquid poly-carbonate/benzene or alkylbenzene mixtures obtainable after the vapour treatment are converted into "semi-solid dispersions" by reducing the temperature and, if appropriate, also by reducing the pressure~ evaporation of the benzene or alkylbenzene being excluded, and these dispersions can be converted into crumbly masses. During this solidification operation, the temperature of the mixture is in each case below the boiling point of the benzene or alkylbenzene at the particular pressure applied.
Examples of suitable apparatuses for the solidi-fication of the polycarbonate/benzene or alkylbenzene mixtures are cooled extruders, cooled kneaders, cool;ng ~5 rollers and cooling belts. Cooled extruders and cooled kneaders are pre~erably used.
The liquid polycarbonate/benzene or alkylbenzene mixtures suitable for the "solidification" should contain concentrations of 3 to 70% by ~eight o~ polycarbonate, ~0 preferably 30 to 70X by weight of polycarbonate~ in the mixture.
I~ necessary~ ~hese concentrations are estab-lished in the customary evaporation apparatuses for vis-cous solutions, such ast for example, thin ~ilm evapora-tors~ multi-phase spiral tubes and falling f;lm evapora~
tors~ by distill;ng off the benzene or alkylbenzene. The pressures to be applied here are 1 to 5 bar absolute.
The temperatures which are thereby established can be obtained from the vapour pressure curve of the benzene or alkylbenzene.
The crumbled, semi-solid polycarbonate/benzene or alkylbenzene mixtures are ~reed from the benzene or alkylbenzene in known driers, such as, for example, plate driers, tumble driers and paddle driers. The temperatures to be applied are between 50 and 220c~ preferably bet-ween 100 and 200C. The drying times are between 30 and Le A 22 921 1~0 minutes, and are preferably 60 to 12û minutes~ undernormal pressure. The speed of drying can be accelerated by applying a vacuum.
It is advantageous to carry out the drying according to a temperature ~rogramme. This means that drying is carried out initially at a lo~ temperature level of between 50 and 140C, preferably at 100 to 130C, and then at a higher temperature level of between ~40 and 220C, preferably between 160 and 200C.
If the concentrations of the crumbled, semi-solid polycarbonate/benzene or alkylbenzene mixtures are bet-ween 3 and 30% by weight, preferably between 3 and 20% by ~eight, part of the benzene or alkylbenzene can be separated off in filter presses before drying. Concen-trations of, for example~ between 10 and ~5% by weight, preferably between 30 and 40~ by ~eight~ can be estab lished by this measure.
Solidified polycarbonate/solvent mixtures ~hich contain solvents, such as, for example, methylene chlor ide, chlorobenzene and the like, by themselves or to gether or also in addition to benzene or alkylbenzenes, cannot be virtually quantitativeLy freed from the sol-vents by a simple drying process. The semi-solid poly~
carbonate/benzene or alkylbenzene mixtures obtained according to the invention exhibit decisive advantages here. Residual contents of benzene or alkylbenzene which are below the detectability limit are achieved.
The polycarbona~es obtained according to the invention, after drying, are crumbs ~hich are white in appearance, can be po~dery to a greater or lesser degree and are virtually free from chlorine and benzene or alkylbenzene. They are advantageously suitable for use in all the fields of application of polycarbonates.
They can be provided with ~he stabilisers, addi-tives and fillers known in the chemistry of thermoplasticpolycarbonates in a known manner. They can be shaped in Le A 22 921 ___ ~2'~
a known manner to the customary shaped polycarbor~ate articles, such as semi-finished products, sheets, tilms and fibres.
Example 3 .
A polycarbonate/toluene mixture ~hich has been obtained according to Example 1 and has been concentrated to 38X by weight in a thin film evaporator is introduced into a kneader cooled with water. After a few seconds, solidification of the m;xture starts, and after 60 seconds the mass crumbles. The product is then dried under normal pressure at 120C for one hour and at 200C for a further hour~ < 10 ppm of toluene are found in the polycarbonate~ The polycarbonate is melted in an extru-der, drawn off as a bristle and granulated. The clear granules are inject;on-moulded to a test piece.
Exam A polycarbonate/toluene mixture concentrated clS
in Example 3 is introduced into a ~ater-cooled twin-screw extruder, the screws of which rotate in the same sense.
After a residence time of 30 seconds, the product leaves the extruder as crumbs. After drying, as described in Example 3~ < 10 ppm of toluene are measured. The powder is processed to a test bar.
Example 5 (Comparison) A liquid polycarbonate/toluene/methylenP chloride mixture consisting of 35X by weight of polycarbonate, 45~ by weight of toluene and 20X by weight of methylene chloride is introduced into a kneader which is cooled wi~h water.
After about 120 seconds, the mixture starts to solidify, and after about a further 120 seconds, it crumbles.
After drying~ as described in Example 3, 255 ppm of toluene and < 10 ppm of methylene chloride are found.
The product is processed to a test bar.
~ (Comparison) A liquid, 30 per cent strength by weight poly-carbonate/chlorobenzene solution is introduced ;nto a Le A 22 921 ~2~ 32 kneader cooled with water. After abou~ 15 minutes, solidification starts, and after about a further 5 minutes~ the product crumbles. After drying, as des-cribed in Example 3, 730 ppm of chlorobenzene are found.
The product is processed to a test bar.
Le A 22 921
Process for the isolation of thermoplastic polycarbonates from th~ir solutions In the known preparat;on of thermoplastic aromatic polycarbonates by the two-phase boundary pro-cess~ the polycarbonates are obtained in the organic phase, from which they must be isolated after this has been separated off and purified. (See, for example, H. Schnell, "Chemistry and Physics of Polycarbonates", 1964, Interscience Publishers, New York, London, Sydney, pages 41 to 44).
For the polycarbonate based on bisphenol Ao which is industrially the most important polycarbonate, there are the following possibilities: one possibili~y for the isolation comprises precipitation of the polycarbonate from its solutions by non-solvent~ (see, for example, U.S. Patents Nos. 3,264,262, 3,26l~263 and 3~264~264).
Toluene, inter alia, is mentioned here as a non solvent.
The precipitation method has the disadvantage ~hat the po~der obtained must be dried and made up into free-flowing granules, which can cause diff;culties if precipitation has not been carried out properly. The recovery of the solvent for the polycarbonate and ~he loss of polycarbonate due to non-quantitative precipi-~ation are ~echnological disadvantages.
An isolation method ~hich is differen~ in prin-ciple leads directly to a polycarbonate melt via evapora-tion of the solvent (see9 for example, U.S. Patent- 3,022,271, DE-OS (German Published Specification) 1,4P4,984 and DE-AS (German Published Specification) 1,209,741). There is the danger here of damage to the polycarbonate, since the last residues of solvent are removed at relatively high temperatures.
The solvent content of polycarbonate solutions can also be reduced by means of water (see U.S. Patent 3,505~73).
It is also possible to add monochlorobenzene or Le A 22 921-US
, ~
~2~
polyhydric alcohols or aqueous solutions of these poly-hydric alcohols to the polycarbonates in amounts of 0.1 to 10% by weight beFore extrusion thereof to remove solvent residues from polycarbonates ~see DE-OS ~German Published SpeciFication~ 2,917,3~6).
Another method for isolating polycarbonate com-prises crystallisation of poLycarbonates from their solu-t;ons, wh;ch is promoted by concentrating the solutions at elevated temperature and/or reduced pressure, or adding non-solvents tsee U.S. Patent 3,112,292, ;n par-ticular column 3, paragraph 3). Solvents for the poLy-carbonate which are recommended here are also, inter alia, benzene, toluene and xylene, although this does not apply to polycarbonates based on bisphenol A, but, for exarple, to polycarbonates from chlorinated bisphenols (see Example 4 of U.S. Patent 3,112,2~2).
S;milar processes are described in the Japanese publications No. 78-137,297 and No. 78~137~29R oF Mit-subishi Gas, wherein polycarbonate solutions are mod;fied by adding non-solvents so that they solidiFy. Needless to say, benzene, toluene and xylene, inter alia, are mentioned as non-solvents~ toluene being effective 3S a particularly suitable non-solvent.
bE-OS (German Published Specific3tion) 2,825~857 describes a particular process for the preparation of polycarbonate from polycarbonate solutions, wherein the solvent is evaporated and the polycarbonate obtained is powdered ;mmediately. Su;table solvents for polycarbon-ates are chlorinated, aliphat;c hydrocarbons and pyridine.
3~ Aromatic hydrocarbons, such as benzene, chlorobenzene and toluene, can be admixed in order to facilitate po~dering oF the polycarbonate. Toluene is co-used in the examples~
A further development of the process oF U.S.
Patent 3~112,292 is described in U.S. Patent 3,322~724, ~here solid polycarbonates instead of non-solvents are added to the polycarbonate solutions in order to cause Le A 22 921 .__ crystallisation of the polycarbonate. Solvents for the polycarbonate which are mentioned are, inter a~ia, ben-zene~ toluene and xylene, in addition to others, but these again are not suitable for polycarbonates based on bisphenol A (in this context, see, for example, the embodiment examples of U.S. Patent Specifica~ion .3,322,~24).
In DE-AS (German Published Specification) 1,100,949, pulverulent polycarbonates are prepared by swelling already isolated polycarbonates with a small amount of organic solvents. Organic solvents mentioned here are benzene, toluene and xylene, inter alia, but these are again presented as b;sphenol A polycarbonate non~solvents and thus convert the bisphenol A polycar-bonate only into a powder in accordance with the processof DE-AS (German Published Specification) 1,100,949.
Another process for isolating polycarbona~es fro~
their solutions comprises tre3ting the polycarbonate solu-tions ~ith steam, ~hich virtually completeLy vaporises the solvent (seeO for e~ampleO U.S. Patent 3,427,370 and European Published Application 0,003,996).
Finally, there is also the possibility of prepar^
ing ~he polycarbonate immediately in solid form if the reaction is carried out ~ith phosgene in the presence of aromatic, optionally chlorinated hydrocarbons, surface-active substances and aqueous alkali solution tsee the Japanese Patent Application of the Kunoshima Chem. Ind.
16907t59 of Z5.5.1959, published on 16.12.1966, No.
2147Z/66)~
30 ~ All these isolation methods still have this or that technological disadvantage, so that there is still a certain need for improvement in the process for isolat-ing polycarbonates based on bisphenol A whilst retaining the good product quality.
The present invention thus relates to a process for the isolation of thermoplastic polycarbonates based Le A 22 921 on bisphenol A from their solu-tions r which is charac-terized in -tha-t the purified polycarbonate solu-tions, prepared in a known manner by the phase boundary process, in organic solven-ts, preferably in ali-phatic chlorinated hydrocarbons, are treated with vapours of benzene or alkylbenzenes, in which the thermoplastic polycarbonate based on bisphenol A is sparingly soluble or insoluble at room temperature and which also in each case have a higher boiling point than the solvent to be evaporated off from the polycarbonate solutions re-sulting from the phase boundary process, the treatment with -the va-pours being continued until the solvent to be evaporated off isevaporated off down to a residual content of less than 0.5% by weight, preferably of less than 0.1~ by weight, based on the total weight of the resulting polycarbonate/benzene or alkylbenzene mix-ture, and in that the polycarbonate is isolated as a melt rom the resulting mix-ture by evaporating off the benzene or alkylbenzene in known apparatuses, pressure being applied.
According to the present invention -there is provided a process for the isolation of a thermop].astic polycarbonate based on bisphenol A, which is prepared by the phase boundary process, from a solution containing an organic solvent comprising (i) continuously treating a solu-tion of said polycarbonate in said organic solvent with a vapor of at least one member selected from the group consis-ting of benzene and alkylbenzene, said member being characterized in that polycarbonate is sparingly soluble or insoluble -therein at room temperature and further in that its boiling point is lower than that of said organic solvent, until said organic solvent is evaporated off down to a residual content of less than 0.5% by weight based on the total weight of the mixture of said polycarbo-nate and said member and (ii) isolating said polycarbonate either as a melt from said mixture by evaporating off said member under pressure or by solidifying said mixture and removing said member by drying.
Examples of alkylbenzenes which are suitable according to the invention are toluene, ethylbenzene and the various xylenes.
Mixtures of benzene with alkylbenzenes are also suitable. Toluene is particularly preferred.
"In which the thermoplastic polycarbonate is sparingly soluble or insoluble at room temperature" in -the context of the process according to the invention means that the thermoplastic polycarbonate based on bisphenol A has a solubility of less than 3%
by weight, based on the weight o:E benzene or alkylbenzene, at room temperature (20C).
"Have a higher boiling point" in the context of the pro-cess according to the invention means that the benzene or the par-ticular alkylbenzene to be selected must have a boiling point under normal pressure at leas-t 20C higher than -the particular organic solvent employed ,-- 4a -~2L~
in the phase boundary process.
The polycarbonate/aromatic mixtures obtained according to the invention can be ~orked up completely by evaporation at high temperatures without damage to ~he polycarbonate or the apparatus. The resulting poly-carbonates are distinguished by their light colour.
Examples of suitable apparatuses for the process according to the invention are columns, bubble columns or cascades of stirred containers.
The process according to the invention is parti-cularly advantageously carried out continuously in a column in ~hich the vaPoUr of the aromatic is blown in from the bottom and the polycarbonate solution resulting from the phase boundary process is introdured at the top.
The polycarbonate/benzene or alkylben~ene mixture is drawn off continuously from the bottom of the column.
The particular organic solvent used in the phase bound-ary process is continuously taken off in vapour form at the top of the column. The temperature programme in the column can be derived from the phas~ equilibrium curve of the particular organic solvent in the phase boundary process and the particular aromatic used. The tempera-ture range for the polycarbonate solution to be fed in can be between 20C and 100C, an~ that of the vapour Z5 of the aromatic can be between 80C and 200C.
The particular temperature level can be modified by applying different increased pressures~
Slight increased pressures are advantageously chosen~ so that the operating conditions in the plants are not close to the limit of the unstable region of the mixtures.
In the case of polycarbonate based on bisphenol A
~here methylene chloride is replaced by toLuene, pres-sures of 1 to 5 bar absolute are sufficient. The tempera-tures are about 41-1oooc at the inlet point for the polycarbonatelmethylene chloride solution and about 112-Le A 22 9~1 36~;~
195C at the ;nlet point for the toluene vapour. Pres-sures o~ 1.5 to 3 bar absolute are preferably established.
The concentrations of polycarbonate in the poly-carbonate solution to be fed in are between 3 and 30X, preferably bet~een 10 and 25%. They are usually hardly var ed by conversion by means of the aromatic vapour treatmen~ according to the invention into the polycarbon-ate/benzene or alkylbenzene mixtures ~ecause of the energy balance, the concentrations may drop slightly, rema;n the same or increase. If desired, there ;s the possibility of establishing higher polycarbonate concen-trations in the polycarbonate/benzene or alkylbenzene mixtures by supplying additional energy.
Since the polycarbonate is isolated via evapora-tion, the rPsulting vapour of the benzene or alkylbenzenecan be utilised directly for evaporating off the organic solvent used in the phase boundary process Thermoplastic polycarbonates based on bisphenol A ;n the context of the present invention are those ~ith Mw between 100~00 and 200,000~ preferably between 20~0ûO
and 8~,000 (Mw determined via the method of light scattering).
Polycarbonates based on bisphenol A are~ on the one hand, bisphenol A homopolycarbonate or those bis-phenol A coPolycarbonates which, in spite of co-using other d;functional components, have the abovementioned poor solubility at room temperature in benzene or in alkylbenzenes of less than 3X by weight.
Examples of other suitable difunctional co~pon-ents are diphenols other than bisphenol A, such as, forexample, 2,2-bis-t3,5-dibromo-4 hydroxyphenyl)-propaneO
Other difunctional components are, for example, also oligomers or polymers which carry two end grouPs which are capable of undergoing a build-up reaction under the cond;tions of polycarbonate synthes;s by the phase boundary process. Examples of such end groups are Le A 22 921 ~2'~
phenolic OH groups, chlorocarbonic acid ester groups and carboxylic acid chloride groups. Previously prepared oligomeric or polymeric blocks which already carry the reactive groups mentioned as a result of the nature of their preparation or in which such groups can be produced by a suitable after-trea~ment are, for example, poly-condensates based on aliphatic diols and saturated ali-phatic dicarboxylic acids, such as, for example, satura-ted aliphatic polyesters on a dimeric fatty acid basis (see, for example, U.S. Patent 4,430,492 or DE-OS ~German Published Specification~ 2,935,317) or also polysiloxanes (see, for example, U.S. Patents 3,419,634, 3,821,325 and 3~832~419)o The phase boundary process for the preparation of the thermoplastic aromatic polycarbonates to be iso-lated accord;ng to the invention is kno~n from the literature.
Especially suitable solvents for the phase boundary process which give polycarbonate solutions which are particularly suitable for the isola~ion process according to the invention are, in particular~ alipha~ic, halogenated hydrocarbons~ such as, for example~ CH2Cl2 or 1,1 dichloroethane. CH2Cl2 is especially suitable.
Known apparatuses for evaporating off the benzene or the alkylbenzenes are~ for example~ thin film evaporators and devolatilisation extrudersO
The polycarbonates isolated by the process accord ing to the invention are light-coloured products and are thus advantageously suitable for use in all the fields of application of polycarbonates.
They can be provided with the stabilisers, addi-tives and fillers known in the chemistry of thermoplastic polycarbonates in a known manner.
They can be shaped to the customary shaped poly-carbonate articles, such as semi-finished products, sheets, films and fibres, in a known manner.
~, Example 1 107 kg/hour of a 16.4X strength polycarbonate/
methylene chloride solution ~hich has been prepared by the phase boundary process are introduced at the top of a distillation column with a diameter of 200 mm and a height of 3,0no mm. 106 kg/hour of 'oluene vapour are passed in at the bottom. The column is operated under normal pressure. 41C ;s measured at the top of the column and 113C is measured at the bottom. The dis-tillate contains 0.43X of toluene; 250 ppm of methylenechloride are found in the polycarbonate/toluene mixture.
The polycarbonate/toluene mixture is pumped into a thin film evaporator operated under an increased pres-sure of 1.2 bar, and 65.5 kg/hour of toluene are dis-tilled off. The concentrated mixture is freed from thetoluene in a devolatilisation extruder.
A polycarbonate with the following characteris~
tic parameters is obtained:
relative viscosity ~ rel. 1.307 (0.5 9 in 100 ml of methylene chloride~
hydrolysable chlorine ~ppm~ < 2 phenolic OH [X~ 0.01 inorganic chlorine ~ppm] < 2 total chlorine ~ppm~ < 2 25 colour number* 0.05 * The colour number is an empirical relative characteris-tic figure. This is defined such that 0.05 units allow a visually perceptible graduation against the light at a test bar th;ckness of 4 mm.
Example 2 The example shows the extent to which polycarbon-ate is damaged by halogenohydrocarbons at high tempera-tures.
20X strength polycarbonate solutions with various solvents were heated at high temperatures in an autoclave with a sample of material 1.4571 for 4 hours~ The Le A 22 921 _ 9 solutions ~ere then taken out of the autoclave, the solvents were removed in a vacuum drying cabinet and the polycarbonate film was dissolved to give a 5X strength solution in pure methylene chloride~ in order to detect differences via the colour number of the solution.
S~lvent Temperature Hazen colour number Methylene chloride ~25C > 300 Chlorobenzene 3Z0C 80-90 Toluene 315C . 20-30 As an advantageous variant of the process accord-ing to the invention, it has also been found that the resulting polycarbonate/benzene or alkylben~ene mixtures give, by cooling, solidified mixtures from uhich the benzene or the alkylbenzenes can be removed virtually 1~ quantitatively by drying.
The present invention thus-also relates to a pro-cess for the isolation of thermoplastic polycarbonates . based on bisphenol A from their solutions, which is charac-terised in that the purified polycarbonate solutions, pre-pared in a known manner by the phase boundary process, inorganic solvents, preferably in aliphat;c chlorinated hydrocarbons~ are treated with vapours of benzene or alkylbenzenes, in which the thermoplast;c polycarbonate based on bisphenol A is sparingly soluble or insoluble at room te~perature and which also in each case have a higher boiling point than the solvent to be evaporated off from the polycarbonate solutions resulting from the phase boundary proress, the treatment with the vapours being continued until the solvent to be evaporated off is evaporated off do~n to a residual content of less than 0.5% by ~eight, preferably of less than 0.1X by weight, based on the total we;ght of the resulting polycarbonatet benzene or alkyLbenzene mixture, and in that the result-ing mixture is soLidified, preferably after concentration, 3~ and the benzene or alkylbenzene is ~hen removed by drying~
"Solidification" in the context of the process Le A 22 921 ___ æ
according to the invention means that the liquid poly-carbonate/benzene or alkylbenzene mixtures obtainable after the vapour treatment are converted into "semi-solid dispersions" by reducing the temperature and, if appropriate, also by reducing the pressure~ evaporation of the benzene or alkylbenzene being excluded, and these dispersions can be converted into crumbly masses. During this solidification operation, the temperature of the mixture is in each case below the boiling point of the benzene or alkylbenzene at the particular pressure applied.
Examples of suitable apparatuses for the solidi-fication of the polycarbonate/benzene or alkylbenzene mixtures are cooled extruders, cooled kneaders, cool;ng ~5 rollers and cooling belts. Cooled extruders and cooled kneaders are pre~erably used.
The liquid polycarbonate/benzene or alkylbenzene mixtures suitable for the "solidification" should contain concentrations of 3 to 70% by ~eight o~ polycarbonate, ~0 preferably 30 to 70X by weight of polycarbonate~ in the mixture.
I~ necessary~ ~hese concentrations are estab-lished in the customary evaporation apparatuses for vis-cous solutions, such ast for example, thin ~ilm evapora-tors~ multi-phase spiral tubes and falling f;lm evapora~
tors~ by distill;ng off the benzene or alkylbenzene. The pressures to be applied here are 1 to 5 bar absolute.
The temperatures which are thereby established can be obtained from the vapour pressure curve of the benzene or alkylbenzene.
The crumbled, semi-solid polycarbonate/benzene or alkylbenzene mixtures are ~reed from the benzene or alkylbenzene in known driers, such as, for example, plate driers, tumble driers and paddle driers. The temperatures to be applied are between 50 and 220c~ preferably bet-ween 100 and 200C. The drying times are between 30 and Le A 22 921 1~0 minutes, and are preferably 60 to 12û minutes~ undernormal pressure. The speed of drying can be accelerated by applying a vacuum.
It is advantageous to carry out the drying according to a temperature ~rogramme. This means that drying is carried out initially at a lo~ temperature level of between 50 and 140C, preferably at 100 to 130C, and then at a higher temperature level of between ~40 and 220C, preferably between 160 and 200C.
If the concentrations of the crumbled, semi-solid polycarbonate/benzene or alkylbenzene mixtures are bet-ween 3 and 30% by weight, preferably between 3 and 20% by ~eight, part of the benzene or alkylbenzene can be separated off in filter presses before drying. Concen-trations of, for example~ between 10 and ~5% by weight, preferably between 30 and 40~ by ~eight~ can be estab lished by this measure.
Solidified polycarbonate/solvent mixtures ~hich contain solvents, such as, for example, methylene chlor ide, chlorobenzene and the like, by themselves or to gether or also in addition to benzene or alkylbenzenes, cannot be virtually quantitativeLy freed from the sol-vents by a simple drying process. The semi-solid poly~
carbonate/benzene or alkylbenzene mixtures obtained according to the invention exhibit decisive advantages here. Residual contents of benzene or alkylbenzene which are below the detectability limit are achieved.
The polycarbona~es obtained according to the invention, after drying, are crumbs ~hich are white in appearance, can be po~dery to a greater or lesser degree and are virtually free from chlorine and benzene or alkylbenzene. They are advantageously suitable for use in all the fields of application of polycarbonates.
They can be provided with ~he stabilisers, addi-tives and fillers known in the chemistry of thermoplasticpolycarbonates in a known manner. They can be shaped in Le A 22 921 ___ ~2'~
a known manner to the customary shaped polycarbor~ate articles, such as semi-finished products, sheets, tilms and fibres.
Example 3 .
A polycarbonate/toluene mixture ~hich has been obtained according to Example 1 and has been concentrated to 38X by weight in a thin film evaporator is introduced into a kneader cooled with water. After a few seconds, solidification of the m;xture starts, and after 60 seconds the mass crumbles. The product is then dried under normal pressure at 120C for one hour and at 200C for a further hour~ < 10 ppm of toluene are found in the polycarbonate~ The polycarbonate is melted in an extru-der, drawn off as a bristle and granulated. The clear granules are inject;on-moulded to a test piece.
Exam A polycarbonate/toluene mixture concentrated clS
in Example 3 is introduced into a ~ater-cooled twin-screw extruder, the screws of which rotate in the same sense.
After a residence time of 30 seconds, the product leaves the extruder as crumbs. After drying, as described in Example 3~ < 10 ppm of toluene are measured. The powder is processed to a test bar.
Example 5 (Comparison) A liquid polycarbonate/toluene/methylenP chloride mixture consisting of 35X by weight of polycarbonate, 45~ by weight of toluene and 20X by weight of methylene chloride is introduced into a kneader which is cooled wi~h water.
After about 120 seconds, the mixture starts to solidify, and after about a further 120 seconds, it crumbles.
After drying~ as described in Example 3, 255 ppm of toluene and < 10 ppm of methylene chloride are found.
The product is processed to a test bar.
~ (Comparison) A liquid, 30 per cent strength by weight poly-carbonate/chlorobenzene solution is introduced ;nto a Le A 22 921 ~2~ 32 kneader cooled with water. After abou~ 15 minutes, solidification starts, and after about a further 5 minutes~ the product crumbles. After drying, as des-cribed in Example 3, 730 ppm of chlorobenzene are found.
The product is processed to a test bar.
Le A 22 921
Claims (9)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A process for the isolation of a thermoplastic polycarbo-nate based on bisphenol A, which is prepared by the phase boundary process, from a solution containing an organic solvent comprising (i) continuously treating a solution of said polycarbonate in said organic solvent with a vapor of at least one member selected from the group consisting of benzene and alkylbenzene, said member being characterized in that polycarbonate is sparingly soluble or insolu-ble therein at room temperature and further in that its boiling point is lower than that of said organic solvent, until said organic solvent is evaporated off down to a residual content of less than 0.5% by weight based on the total weight of the mixture of said po-lycarbonate and said member and (ii) isolating said polycarbonate either as a melt from said mixture by evaporating off said member under pressure or by solidifying said mixture and removing said member by drying.
2. A process according to claim 1, in which the organic sol-vent is evaporated off down to a residual content of less than 0.1%
by weight, based on the total weight of the resulting polycarbonate/
benzene or polycarbonate/alkylbenzene mixture.
by weight, based on the total weight of the resulting polycarbonate/
benzene or polycarbonate/alkylbenzene mixture.
3. The process of claim 1 wherein said alkyl benzene is se-lected from the group consisting of toluene, ethylbenzene and xylene.
4. The process of claim 2 wherein said alkyl benzene is toluene.
5. A process according to claim 1, in which the organic sol-vent is an aliphatic chlorinated hydrocarbon.
6. A process according to claim 5, in which the organic sol-vent is methylene chloride.
7. A process according to claim 1, in which the treatment with the vapour is carried out continuously in a column.
8. A process according to claim 1, in which following treat-ment with the vapour, polycarbonate/benzene or polycarbonate/alkyl-benzene mixture is solidified and the benzene or alkylbenzene is then removed by drying.
9. A process according to claim 8, in which the polycarbona-te/benzene or polycarbonate/alkylbenzene mixture is solidified, after being concentrated to a concentration of 30 to 70% by weight.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DEP3429960.2 | 1984-08-16 | ||
| DE19843429960 DE3429960A1 (en) | 1984-08-16 | 1984-08-16 | METHOD FOR INSULATING THERMOPLASTIC POLYCARBONATES FROM ITS SOLUTIONS |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1248682A true CA1248682A (en) | 1989-01-10 |
Family
ID=6243058
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000488659A Expired CA1248682A (en) | 1984-08-16 | 1985-08-14 | Process for the isolation of thermoplastic polycarbonates from their solutions |
Country Status (5)
| Country | Link |
|---|---|
| US (1) | US4631338A (en) |
| EP (1) | EP0175118B1 (en) |
| JP (1) | JPS6155118A (en) |
| CA (1) | CA1248682A (en) |
| DE (2) | DE3429960A1 (en) |
Families Citing this family (17)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2528838B2 (en) * | 1986-10-14 | 1996-08-28 | ソニー株式会社 | Optical information recording medium |
| DE3812049A1 (en) * | 1988-04-12 | 1989-10-26 | Bayer Ag | METHOD FOR PRODUCING AROMATIC POLYCARBONATES, AROMATIC POLYESTER CARBONATES AND AROMATIC POLYESTERS |
| DE3819943A1 (en) * | 1988-06-11 | 1990-02-08 | Bayer Ag | METHOD FOR PRODUCING AROMATIC POLYCARBONATES, AROMATIC POLYESTER CARBONATES AND AROMATIC POLYESTERS |
| DE102008008842A1 (en) | 2008-02-13 | 2009-08-27 | Bayer Materialscience Ag | Alkylphenol for molecular weight adjustment and polycarbonate compositions having improved properties |
| ATE516316T1 (en) | 2008-02-13 | 2011-07-15 | Bayer Materialscience Ag | METHOD FOR PRODUCING POLYCARBONATES |
| DE102008008841A1 (en) | 2008-02-13 | 2009-08-20 | Bayer Materialscience Ag | Preparing (co)polycarbonate or diaryl carbonate, useful in e.g. sunglasses, comprises converting di-, mono-phenol and phosgene to chloroformic acid aryl ester, oligo- or diaryl-carbonate, and reacting the product under alkaline solution |
| DE102008011473A1 (en) | 2008-02-27 | 2009-09-03 | Bayer Materialscience Ag | Process for the production of polycarbonate |
| DE102008012613A1 (en) | 2008-03-05 | 2009-09-10 | Bayer Materialscience Ag | Process for the preparation of polycarbonate by the interfacial process |
| DE102008023800A1 (en) | 2008-05-15 | 2009-11-19 | Bayer Materialscience Ag | Alkyl phenol for molecular weight adjustment and copolycarbonate with improved properties |
| EP2256146A1 (en) | 2009-05-30 | 2010-12-01 | Bayer MaterialScience AG | Extremely pure polycarbonate having good natural colour and thermal resistance and a device and method for production of same |
| US10021027B2 (en) | 2013-04-30 | 2018-07-10 | Comcast Cable Communications, Llc | Network validation with dynamic tunneling |
| CN105916908B (en) | 2014-01-24 | 2018-09-07 | 科思创德国股份有限公司 | The method for preparing makrolon according to boundary method |
| EP2965889A1 (en) | 2014-07-11 | 2016-01-13 | Covestro Deutschland AG | Mixing elements with improved dispersant effect |
| EP3719052B1 (en) | 2019-04-03 | 2022-03-02 | Covestro Deutschland AG | Method for the preparation of polycarbonate with reduced phosgen excess |
| EP3719051B1 (en) | 2019-04-03 | 2021-11-03 | Covestro Deutschland AG | Method for the preparation of the polycarbonate addition time of the chain breaking agent |
| EP3985047A1 (en) | 2020-10-13 | 2022-04-20 | Covestro Deutschland AG | Method for the preparation of a polycarbonate based on the interfacial process with solvent exchange |
| EP4083106B1 (en) | 2021-04-30 | 2024-04-10 | Covestro Deutschland AG | Method for the preparation of polycarbonate with improved sustainability |
Family Cites Families (16)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB808488A (en) * | 1955-12-21 | 1959-02-04 | Bayer Ag | Process for the production of high molecular weight polycarbonates |
| GB861918A (en) * | 1958-05-19 | 1961-03-01 | Onderzoekings Inst Res | Preparation of polycarbonate in particulate form |
| US3112292A (en) * | 1958-06-23 | 1963-11-26 | Bayer Ag | Production of linear crystallized polycarbonates |
| US3022271A (en) * | 1960-08-10 | 1962-02-20 | Pittsburgh Plate Glass Co | Finishing of solid diphenolic polycarbonates |
| BE589858A (en) * | 1959-04-25 | |||
| DE1191956B (en) * | 1962-08-13 | 1965-04-29 | Bayer Ag | Process for the evaporation of solutions from plastics in organic solvents |
| DE1213610B (en) * | 1962-08-18 | 1966-03-31 | Bayer Ag | Process for the production of high molecular weight, linear, thermoplastic polycarbonates in solid form from solutions |
| DE1209741B (en) * | 1963-03-28 | 1966-01-27 | Bayer Ag | Extraction of thermoplastic polycarbonates from solutions |
| US3264262A (en) * | 1963-05-22 | 1966-08-02 | Mobay Chemical Corp | Polycarbonate recovery system |
| US3264264A (en) * | 1963-05-22 | 1966-08-02 | Mobay Chemical Corp | Polycarbonate recovery system |
| US3264263A (en) * | 1963-05-22 | 1966-08-02 | Mobay Chemical Corp | Polycarbonate recovery system |
| US3454526A (en) * | 1964-12-10 | 1969-07-08 | Bayer Ag | Method for solution spinning polycarbonate filaments |
| US3505273A (en) * | 1967-05-04 | 1970-04-07 | Mobay Chemical Corp | Method for reducing the solvent content of a polycarbonate |
| US4184911A (en) * | 1977-06-13 | 1980-01-22 | Mitsubishi Gas Chemical Company | Process for producing powdery polycarbonate from a polycarbonate solution |
| IT1094162B (en) * | 1978-02-22 | 1985-07-26 | Montedison Spa | CONTINUOUS PROCESS FOR THE RECOVERY OF POLYCARBONATE FROM ITS SOLUTIONS |
| NL7903332A (en) * | 1979-04-26 | 1980-10-28 | Gen Electric | THERMOPLASTIC MOLDING MIX AND METHOD FOR PREPARING THEREOF. |
-
1984
- 1984-08-16 DE DE19843429960 patent/DE3429960A1/en not_active Withdrawn
-
1985
- 1985-08-05 DE DE8585109811T patent/DE3565115D1/en not_active Expired
- 1985-08-05 US US06/762,209 patent/US4631338A/en not_active Expired - Fee Related
- 1985-08-05 EP EP85109811A patent/EP0175118B1/en not_active Expired
- 1985-08-13 JP JP60177055A patent/JPS6155118A/en active Granted
- 1985-08-14 CA CA000488659A patent/CA1248682A/en not_active Expired
Also Published As
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|---|---|
| JPS6155118A (en) | 1986-03-19 |
| EP0175118A1 (en) | 1986-03-26 |
| JPH0556771B2 (en) | 1993-08-20 |
| US4631338A (en) | 1986-12-23 |
| DE3565115D1 (en) | 1988-10-27 |
| DE3429960A1 (en) | 1986-02-27 |
| EP0175118B1 (en) | 1988-09-21 |
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