CA1050693A - Production of modified polyalkylene terephthalates - Google Patents
Production of modified polyalkylene terephthalatesInfo
- Publication number
- CA1050693A CA1050693A CA204,585A CA204585A CA1050693A CA 1050693 A CA1050693 A CA 1050693A CA 204585 A CA204585 A CA 204585A CA 1050693 A CA1050693 A CA 1050693A
- Authority
- CA
- Canada
- Prior art keywords
- glycol
- dicarboxylic acid
- terephthalate
- aliphatic dicarboxylic
- acid
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
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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
- C08G63/02—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
- C08G63/181—Acids containing aromatic rings
- C08G63/183—Terephthalic acids
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- Chemical & Material Sciences (AREA)
- Health & Medical Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Medicinal Chemistry (AREA)
- Polymers & Plastics (AREA)
- Organic Chemistry (AREA)
- Polyesters Or Polycarbonates (AREA)
Abstract
ABSTRACT OF THE DISCLOSURE:
A process for the production of a modified polyalkylene tere-phthalate from the radical of terephthalic acid and the radical of a glycol of two to six carbon atoms in which from 1 to 50 mole % of the terephthalic acid radical has been replaced by an aliphatic dicarboxylic acid radical of four to twelve carbon atoms. The aliphatic dicarboxylic acid is esterified by heating with the glycol in a molar ratio of from 1:1.2 to 1:1.8 at a temperature of from about 5 to 20°C below the boiling point of the glycol until the degree of esterification is from 90 to 95 mole % based on the aliphatic dicarboxylic acid; a dialkyl terephthalate is transesterified with the glycol in a molar ratio of from 1:1.2 to 1:2 in the presence of a catalyst in an amount of from 0.01 to 0.2% by weight base on dialkyl-terephthalate by heating to a temperature of from 130° to 240°C at atmospheric pressure until at least 95% of the alkoxy groups present have been eliminated.
The esterification product is mixed with the transesterification product and polycondensation is carried out at a temperature of from 240° to 290°C and a pressure of from 0.1 to 760 mm, in the presence of a catalyst in an amount of from 0.01 to 0.2% by weight based on the polyester. The polyester obtained is suitable for example for mouldings or as an adhesive.
A process for the production of a modified polyalkylene tere-phthalate from the radical of terephthalic acid and the radical of a glycol of two to six carbon atoms in which from 1 to 50 mole % of the terephthalic acid radical has been replaced by an aliphatic dicarboxylic acid radical of four to twelve carbon atoms. The aliphatic dicarboxylic acid is esterified by heating with the glycol in a molar ratio of from 1:1.2 to 1:1.8 at a temperature of from about 5 to 20°C below the boiling point of the glycol until the degree of esterification is from 90 to 95 mole % based on the aliphatic dicarboxylic acid; a dialkyl terephthalate is transesterified with the glycol in a molar ratio of from 1:1.2 to 1:2 in the presence of a catalyst in an amount of from 0.01 to 0.2% by weight base on dialkyl-terephthalate by heating to a temperature of from 130° to 240°C at atmospheric pressure until at least 95% of the alkoxy groups present have been eliminated.
The esterification product is mixed with the transesterification product and polycondensation is carried out at a temperature of from 240° to 290°C and a pressure of from 0.1 to 760 mm, in the presence of a catalyst in an amount of from 0.01 to 0.2% by weight based on the polyester. The polyester obtained is suitable for example for mouldings or as an adhesive.
Description
O~Z, 30~00'~
,~
PRODUCTION OF MODIFIED POLYALKYLENE TEREPHTHALATES
The invention relates to a process for the production of a modified polyalkylene terephthalate in which a portion Or the tere- -phthalic acid is replaced by an aIiphatic dicarboxylic acid.
It is known that polyesters can be prepared by reacting an aromatic or aliphatic dicarboxylic acid or ester with an aliphatic glycol. This reaction which proceeds with elimination of water or ~-alcohol is usually carried out on an industrial scale~in two or more stages.
:' For example when dimethyl terephthalate is used as the starting ;
ester, this may first be reacted with ethylene glycol to Porm di-ethylene glycol terephthalate or an oligomeric condensation product of the same. The product obtaine~ is then polycondensed in~o a hi~h molecular weight-reaction product batchwise or continuously with the -~
elimination of glycol.
To prepare a modified polyester which offers particular ad-.
vantages in certain applications it is possible in principle to re-place some of the terephthalic acid component by a suitable aliphati~
dicarboxylic acid. The methods available differ in the type of com-ponent added and the point in time at which it is introduced.
For example it is known from German Laid-Open Specification (DOS) No. 1,520,284 that modified polyalkylene terephthalates can be ~.
prepared by transesterifying a mixture of dimethyl te~ephthalate ~ , i,.,.. ,., .. ... , :
... ~ . . .. . . . .. ~ . , , . ,,: . : , . .. .
O Z. 30,007 ~ ~ 5~ ~g 3 and a dialkyl ester of an aliphatic dicarboxylic acid with a glycol in the presence of a suitable transesterification catalyst such as a zinc, manganese or calcium compound to form the corresponding glycol ester, the monofunctional alcohol liberated being removed by distillation. The resulting reaction mixture of monomeric and oligomeric glycol esters, after the addition of a suitable poly-condensation catalyst such as an antimony or germanium compound, is converted by a conventional method into a high molecular weight polycondensation product.
This process may often be carried out on an industrial scale without any particular problems. It offers advantages particularly when the acid used for modification is difficult to purify as such because of a high melting or boiling point and low solubility in cheap solvents and therefo~e purification iB effected by the cumber-some routeinvolving the corresponding dialkyl esterO When the acid in question can be conventionally purified in free form and used for the produetion of technical derivatives 3 as in the case o~
adipic and sebacic acids, the roundabout method via the dialkyl ester is avoided for reasons of economyO
Furthermore it is known from German Laid-Open Specification (DOS) No 1,520,284 that modified polyalkylene terephthalates can be prepared by reacting dimethyl terephthalate with a suikable glycol in the presence of a suitable transesterification catalyst, then adding to the mixture the free acid servin~ to modify the ester and reacting this three-component mixture finally in a conventional manner to form a high molecular weight copolyester. The acid is added in solid or molten form, This process does avoid the troublesome pro-duction of the dialkyl ester concerned but it still has some serious disadvantages. Firstly the introduction of the solid product into the transesterification m~xture offers problems particularly when adipic acid is used as the modi~ying agentO When adipic acid or another aliphatic acid is added in solid form there are serious
,~
PRODUCTION OF MODIFIED POLYALKYLENE TEREPHTHALATES
The invention relates to a process for the production of a modified polyalkylene terephthalate in which a portion Or the tere- -phthalic acid is replaced by an aIiphatic dicarboxylic acid.
It is known that polyesters can be prepared by reacting an aromatic or aliphatic dicarboxylic acid or ester with an aliphatic glycol. This reaction which proceeds with elimination of water or ~-alcohol is usually carried out on an industrial scale~in two or more stages.
:' For example when dimethyl terephthalate is used as the starting ;
ester, this may first be reacted with ethylene glycol to Porm di-ethylene glycol terephthalate or an oligomeric condensation product of the same. The product obtaine~ is then polycondensed in~o a hi~h molecular weight-reaction product batchwise or continuously with the -~
elimination of glycol.
To prepare a modified polyester which offers particular ad-.
vantages in certain applications it is possible in principle to re-place some of the terephthalic acid component by a suitable aliphati~
dicarboxylic acid. The methods available differ in the type of com-ponent added and the point in time at which it is introduced.
For example it is known from German Laid-Open Specification (DOS) No. 1,520,284 that modified polyalkylene terephthalates can be ~.
prepared by transesterifying a mixture of dimethyl te~ephthalate ~ , i,.,.. ,., .. ... , :
... ~ . . .. . . . .. ~ . , , . ,,: . : , . .. .
O Z. 30,007 ~ ~ 5~ ~g 3 and a dialkyl ester of an aliphatic dicarboxylic acid with a glycol in the presence of a suitable transesterification catalyst such as a zinc, manganese or calcium compound to form the corresponding glycol ester, the monofunctional alcohol liberated being removed by distillation. The resulting reaction mixture of monomeric and oligomeric glycol esters, after the addition of a suitable poly-condensation catalyst such as an antimony or germanium compound, is converted by a conventional method into a high molecular weight polycondensation product.
This process may often be carried out on an industrial scale without any particular problems. It offers advantages particularly when the acid used for modification is difficult to purify as such because of a high melting or boiling point and low solubility in cheap solvents and therefo~e purification iB effected by the cumber-some routeinvolving the corresponding dialkyl esterO When the acid in question can be conventionally purified in free form and used for the produetion of technical derivatives 3 as in the case o~
adipic and sebacic acids, the roundabout method via the dialkyl ester is avoided for reasons of economyO
Furthermore it is known from German Laid-Open Specification (DOS) No 1,520,284 that modified polyalkylene terephthalates can be prepared by reacting dimethyl terephthalate with a suikable glycol in the presence of a suitable transesterification catalyst, then adding to the mixture the free acid servin~ to modify the ester and reacting this three-component mixture finally in a conventional manner to form a high molecular weight copolyester. The acid is added in solid or molten form, This process does avoid the troublesome pro-duction of the dialkyl ester concerned but it still has some serious disadvantages. Firstly the introduction of the solid product into the transesterification m~xture offers problems particularly when adipic acid is used as the modi~ying agentO When adipic acid or another aliphatic acid is added in solid form there are serious
-2-,. - - . , . ; : , O~Z, 30,~07 1 ~ 5~ 6~ ~
di~riculties because it is moistened by ascending glycol vapor, which eventually results in troublesome stoppage of the supply members such as star feeders or screw conveyers, The addition of adipic acid in molten form is also fraught with problems because the acid very readily forms byproducts in the molten condition and these seriously impair the quality of the polyester and particularly its color~ Another disadvantage in the acldition of free acids to the transesterification mixture is that considerable amounts Or water of reaction are formed in the subsequent esterification reaction and this contaminates the methanol and glycol distilled off, limits their applications and adds to the cost of processing. The water formed also causes di~ficulties in the subsequent evacuation of the reaction mixtùre because the necessary final vacuum of about 1 mm is only set up with great delay so that polycondensation takes appreciably longer and this again results in impairment of quality and increase in the price of the product. The presence of large amounts of free acid in the transesterification mixture may result in insoluble salts being ` formed with the transesterification catalyst~ which are deposited in the reactors and pipelines, especially in continuous operation, and may have unpleasant consequences, Addition of free dicarboxylic acid prior to the transesteri-; fication of the dimethyl terephthalate with the glycol in question is ruled out in most cases because the metal-catalyzed transesteri-fication reaction is markedly slowed down by small amounts o~
acid.
Another possibility for the production of polyalkylene tere-phthalates modified with dicarboxylic acids consists in introducing the bisglycol ester of the modifying acid instead of the free acid itself into the transesterification mixture (cf. O.B. Edgar and E. Ellery, J. Chem, Soc. 1952, page 2633). The bisglycol ester used ~or modification is prepared separately by quantitative esterification of adipic acid with the glycol concerned in a molar ratio of 1:2.
These methods avoid some of the above disadvantages in-bhat the OOZo 30,007 ~ 5~ ~ 3 e~terification reaction is carried out at atmo~pheric pressure and without the use of esteri~ication cataly~tsO On the other hand it is time-consuming because o~ the complete esterification Or the free acid and is uneconomic because of the ~airly large amount o~ glycol us ed O
~ he object of the invention~ apart from the avoidance o~ the disadvantages of the prior art methods, is mainly the use o~ a smaller amount of glycol with the simultaneous shortening of reaction periods.
This object is achieved by the invention~
The invention consists in a process for the production of a modi-fied polyalkylene terephthalate from terephthalate acid and a glycol in whlch up to 50% molar o~ the terephthalic acid radical is replaced by an aliphatic dicarboxylic acid radical of ~our to twelve carbon atoms wherein an aliphatic dicarboxylic acid is esterified with the polyester-forming glycol in a molar ratio of from 1:102 to 1:1.8 - until a degree of esterification o~ ~rom 90 to 95 mole% has been achieved (based on the aliphatic dicarboxylic acid), the esteri-fication mixture thus obtained is mixed with a transesteri~ication mixture of a dialkyl terephthalate and the polyester-~orming glycol obtained by a conventional method and this mixture is polycondensed by a conventional method.
Aliphatic dicarboxylic acids Or four to twelve carbon atoms, ~or example glutaric acid, adipic acid, suberic acid, azelaic acid and sebacic acid, may be used ~or modification of polyalkylene tere-phthalates by the process according to the invention.
From 1 to 50 mole% and preferably from 3 to 40 mole% of the ; terephthalic acid in the polyalkylene terephthalate may be replaced by the modi~ying dicarboxylic acid.
Particularly suitable glycol components are aliphatic glycols of two to six and advantageously o~ two to four carbon atoms such as ethylene glycol~ butanediol-1,4 or hexanediol-1,6.
It is al90 possible in principle to prepare by the process according to the invention a copolyester which contains chemically O.Z. 30,007 ~ S~ ~9 3 combined therein, in addition to terephthalic acid, two or more different aliphatic dicarboxylic acids and two or more difrerent glycols~ The additional modifying components(s) may be used for example as free glycols in the transesterification reaction or as free dicarboxylic acids and free glycols in the esterification reac-tion.
The esterification mixture may be prepared for example as follows The alipha~ic dicarboxylic acid and the glycol are placed in 10 the said molar ratio in a heatable stirred container provided with a column or dephlegmatorO The mixture is heated at atmospheric pressure in the course of from one hour to two hours to a temperature which is from about 5 to 20C below the boiling point of the glycol.
During the heating up phase considerable amounts of water of reaction develop and these are removed overheadO The reflux from the column or the temperature of the dephlegmator is regulated so that the water is substantially separated ~rom entrained vaporous glycolO
A reflux ratio of 1:1 or a temperature in the dephlegmator of from lQl to 102C is generally sufficient, The reaction may be convenient-, 20 ly monitored by the amount of distillate obtained or by determiningthe acid value in samples of the esterification mixtureO At starting molar ratios of dicarboxylic acid to glycol of from 1:1.2 to 1~1.8 a reaction period of from two to four hours is generally ~ufficient ' to set up the required degree of ester,ification Or from 90 to 95 ; mole%, The esterification mixture contains mainly diglyool ester o~
the aliphatic dicarboxylic acid and oligomers of the same. The mean degree of polycondensation is less than 5. The molar ratio of the starting components: dicarboxylic acid and glycol in the production o~ the esterification mixture is advantageously rrom 1~ to 1:1,6, 30 At a higher glycol fraction than 1:108 the proce~s becomes increasingly uneconomic and at lower than 1:1,2 a marked prolongation of the ester-ification period has to be tolerated.
:' .
O, Z, 30 J007 ~5~)6~3 The production of the tran3esteri~ication mixture is carried out by conventional methods from a dialkyl ester of terephthalic acid, particularly dimethyl terephthalate and the appropriate ~lycol or glycols. It is generally carried out at atmospheric pressure and at a temperature o~ rrom 130 to 240 C0 It is generally advisable to carry out this reaction quickly and under mlld conditions because otherwise undesirable side reactions such as the formation of di-glycol or possibly of tetrahydrofuran may occur. The molar ratio of dialkyl terephthalate; to glycol is generally from 1:1,2 to 1:2 10 and preferably from 1:102 to 1:1.8. As a rule the lowest possible glycol fraction is chosen so as to keep the cost of the substance used low and to lessen the formation of byproducts~ The transesteri-fication reaction is generally carried out in the presence of ~
Suitable transesterification catalyst such as a zinc, manganese, calcium or titanium compound and the amount added is generally from 0~01 to 0.2% by weight based on dialkyl terephthalate, The trans esterification is generally continued until at least 95% of the total alkoxyl groups present has been eliminated. The transesteri~ication mixture then consist~ mainly o~ diglycol terephthalate and its oligo-20 meric precondensates. The mean degree of polycondensation is con-veniently less than 10, The esterification mixture and the transesterification mixture ~ may be combined immediately a~ter their separate production9 i.e.
; while still hot at temperatures of from 200 to 240C and well ~` mixed. This may be carried out on an industrial scale by means of metering pumps which can be controlled by means of suitable flow meters. Mixing may be carried out by conventional stirring means or static mixers, It is also possible however for the esterification mixture, 30 i.e. the modifying component, to be cooled for example to a temper-' ature of for example 30 to 100C, to be kept in suitable storage vessels and only then to be added to the transesterification mixture, After the esterification mixture has been brought to~ether -, . . ., ~ . . . .
OOZo 303007 ~ 0 5~ ~ 3 with the transesterification mixture the polycondensation is carried out by a conventional method and evacuation to the neccessary reac-tion pressure is carried out before, during or after the heating up period.
Polycondensation of the mixture should also be carried out as mild~y as possible~ i.e. at the lowest possible temperature and in the shortest possible time, in order to lessen the formation of by-products such as diglycol or tetrahydrofuran and to lessen thermal degradation. The polycondensation is accordingly carried out generally at a temperature of from 240 to 290 and preferably at from 250 to 280C and at a pressure of from 760 mm down to Ool mm. The reaction is usually carried out in the presence of a suitable polycondensation catalyst such as an antimony, germanium or titanium compound generally in an amount'of`from OoOl to 0~2% by weight based on the polyester in question and a stabilizer containing phosphorus such as triphenyl phosphate, also in an amount of from OoOl to 002%. Copolyesters having relative viscosities of more than 1.30 and particularly 1.35 (measured in 0.5% by weight solution in a mixture of phenol and o- '' dichlorobenzene in a ratio by weight of 3:2 at 25C in an Ubbel~hde ~`
viscometer) may thus be achieved in rapidly proceeding polyconden~ ;
sation reactions,. ~ ' Modification of polyesber~ may be carried out with great advantages according to the process of the invention; the produc~ion of the ~-~
modifying agent is simple and does not requ~re great expenditure for apparatus, for example in apparatus operated at atmospheric pressure and without the use of a catalyst~ The economical disadvantage of using a large amount of glycol is avoided so that a substantial ~, ;
shortening of the reaction period required for the production of the esterification mixture as modifying agent is possible.
It was not foreseeable that the reaction period for the esteri-~ication o~ aliphatic dicarboxylic acids with aliphatic glycols using a molar ratio o~ from 1:102 to 1:1.8 is only trivially di~ferent when the degree of esterification is 1 mited to from 90 to 95% of the ,' -O.Z~ 30~007 5~ ~ 3 amount of dicarboxylic acid used and that the esterirication mixture o~ monomer and oligomeric glycol esters of dicarboxylic acids can be used for the production of modified polyesters without impairment of product quality or processO
; The esterification mixture of aliphatic dicarboxylic acidQn~ ylyc~l may easily be stored for a long time at slightly elevated temperature without impairment of qualityO Metering the molten modifying agent offers no technical problemsO Contamination o~ the alcohol and glycol distillate with water of reaction is considerably lessened in this 10 method and this is of great advantage because these distillates other-wise can only be supplied for further industrial use with di~ficulty and at great expense. The process according to the invention moreover avoids the formatlon of troublesome deposits and problems in the - polycondensation stage by the water of reaction formedO
- The process may be carried out advantageously batchwise or con-tinuously in conventional polyesker plant.
Polyesters obtained according to the in~ention are distinguished -~
by a low content of byproducts such as diglycol and accordingly ex-hibit good stability. The color of the products is also éxcellent~
Conventional additives such as pigments, antistatic agents, dyes~ glass fibers, stabilizers or fireproofing agents may be incor~
porated before, during orafter the polycondensation in the production of modified polyesters by the process according to the invention~
Modi~ied polyalkylene terephthala~es obtained according ~o the invention may be further processed for exarnple into fibersg fila-ments~ threads, film, sheeting or injection moldings either imme-diately or after conversion into chips cr` the like via a melt.
.. . .,.................................... , :.
Textile moldings even with relatively slight modi~icationg for example with from 5 to 10 mole% of aliphatic dicarboxylic acid, ex-~ hibit a greatly improved dyeing behavior; at a higher content ofaliphatic dicarboxylic acid, ~or example with from 10 to 30 mole%, they may be used for example as bonding `fibers for the production :. - , ~ ' . . . . .
0.~. 30,007 10 ~ ~ 3 of nonwovens. Copolyesters prepared according to the invention and particularly modiried polybutylene terephthalates, may also be used as hot-melt adhesives in the shoe industryO
The following Examples illustrate the inventionO The parts and percentages are by weightO
; (1) PRODUCTION OF THE ESTERIFICATION MIXTURE USED FOR THE
MODIFICATION:
A mixture of 292 parts (2 kmoles) of adipic acid and 186 parts (3 kmoles) of ethylene glycol is heated to 180C within one hour in a stirred vessel which is combined with a packed column having a re-flux divider and a condenser downstream of the same. The water of reaction formed in the esterification is separated from vaporous , entrained ethylene glycol through the rectifying column at a reflux - ratio of 1:1 o The reaction is monitored by determination of the acid ' number of the esteri~ication mixture and with the knowledge of the operating oapacity of the column by the amount o~ distillate. A~ter a reaction perlod o~ three hours at 180C a reaction mixture having a degree o~ esterification of about 93% (based on the free adipic -~
, 20 acid used) has ~ormed in the vessel. `~
CQMPARATIVE EXPERIMENT:
292 parts (2 kmoles) of adipic acid and 248 parts (4 kmoles) o~ ethylene glycol are used ~or the production of the esterif'ication , mixture. I~ a substantially quantitative esterification, i.e. a degree of esterification of about 99%, is required under otherwise the same , conditions, the reaction period at 180 C is about eight hours.
(2) PRODUCTION OF A TRANSESTERIFICATION MIXTURE FROM DIMETHYL ~ ;
TEREPHTHALATE AND ETHYLENE GLYCOL ~
97 parts (0.5 kmole) and 62 parts (1 kmole) of ethylene - `
di~riculties because it is moistened by ascending glycol vapor, which eventually results in troublesome stoppage of the supply members such as star feeders or screw conveyers, The addition of adipic acid in molten form is also fraught with problems because the acid very readily forms byproducts in the molten condition and these seriously impair the quality of the polyester and particularly its color~ Another disadvantage in the acldition of free acids to the transesterification mixture is that considerable amounts Or water of reaction are formed in the subsequent esterification reaction and this contaminates the methanol and glycol distilled off, limits their applications and adds to the cost of processing. The water formed also causes di~ficulties in the subsequent evacuation of the reaction mixtùre because the necessary final vacuum of about 1 mm is only set up with great delay so that polycondensation takes appreciably longer and this again results in impairment of quality and increase in the price of the product. The presence of large amounts of free acid in the transesterification mixture may result in insoluble salts being ` formed with the transesterification catalyst~ which are deposited in the reactors and pipelines, especially in continuous operation, and may have unpleasant consequences, Addition of free dicarboxylic acid prior to the transesteri-; fication of the dimethyl terephthalate with the glycol in question is ruled out in most cases because the metal-catalyzed transesteri-fication reaction is markedly slowed down by small amounts o~
acid.
Another possibility for the production of polyalkylene tere-phthalates modified with dicarboxylic acids consists in introducing the bisglycol ester of the modifying acid instead of the free acid itself into the transesterification mixture (cf. O.B. Edgar and E. Ellery, J. Chem, Soc. 1952, page 2633). The bisglycol ester used ~or modification is prepared separately by quantitative esterification of adipic acid with the glycol concerned in a molar ratio of 1:2.
These methods avoid some of the above disadvantages in-bhat the OOZo 30,007 ~ 5~ ~ 3 e~terification reaction is carried out at atmo~pheric pressure and without the use of esteri~ication cataly~tsO On the other hand it is time-consuming because o~ the complete esterification Or the free acid and is uneconomic because of the ~airly large amount o~ glycol us ed O
~ he object of the invention~ apart from the avoidance o~ the disadvantages of the prior art methods, is mainly the use o~ a smaller amount of glycol with the simultaneous shortening of reaction periods.
This object is achieved by the invention~
The invention consists in a process for the production of a modi-fied polyalkylene terephthalate from terephthalate acid and a glycol in whlch up to 50% molar o~ the terephthalic acid radical is replaced by an aliphatic dicarboxylic acid radical of ~our to twelve carbon atoms wherein an aliphatic dicarboxylic acid is esterified with the polyester-forming glycol in a molar ratio of from 1:102 to 1:1.8 - until a degree of esterification o~ ~rom 90 to 95 mole% has been achieved (based on the aliphatic dicarboxylic acid), the esteri-fication mixture thus obtained is mixed with a transesteri~ication mixture of a dialkyl terephthalate and the polyester-~orming glycol obtained by a conventional method and this mixture is polycondensed by a conventional method.
Aliphatic dicarboxylic acids Or four to twelve carbon atoms, ~or example glutaric acid, adipic acid, suberic acid, azelaic acid and sebacic acid, may be used ~or modification of polyalkylene tere-phthalates by the process according to the invention.
From 1 to 50 mole% and preferably from 3 to 40 mole% of the ; terephthalic acid in the polyalkylene terephthalate may be replaced by the modi~ying dicarboxylic acid.
Particularly suitable glycol components are aliphatic glycols of two to six and advantageously o~ two to four carbon atoms such as ethylene glycol~ butanediol-1,4 or hexanediol-1,6.
It is al90 possible in principle to prepare by the process according to the invention a copolyester which contains chemically O.Z. 30,007 ~ S~ ~9 3 combined therein, in addition to terephthalic acid, two or more different aliphatic dicarboxylic acids and two or more difrerent glycols~ The additional modifying components(s) may be used for example as free glycols in the transesterification reaction or as free dicarboxylic acids and free glycols in the esterification reac-tion.
The esterification mixture may be prepared for example as follows The alipha~ic dicarboxylic acid and the glycol are placed in 10 the said molar ratio in a heatable stirred container provided with a column or dephlegmatorO The mixture is heated at atmospheric pressure in the course of from one hour to two hours to a temperature which is from about 5 to 20C below the boiling point of the glycol.
During the heating up phase considerable amounts of water of reaction develop and these are removed overheadO The reflux from the column or the temperature of the dephlegmator is regulated so that the water is substantially separated ~rom entrained vaporous glycolO
A reflux ratio of 1:1 or a temperature in the dephlegmator of from lQl to 102C is generally sufficient, The reaction may be convenient-, 20 ly monitored by the amount of distillate obtained or by determiningthe acid value in samples of the esterification mixtureO At starting molar ratios of dicarboxylic acid to glycol of from 1:1.2 to 1~1.8 a reaction period of from two to four hours is generally ~ufficient ' to set up the required degree of ester,ification Or from 90 to 95 ; mole%, The esterification mixture contains mainly diglyool ester o~
the aliphatic dicarboxylic acid and oligomers of the same. The mean degree of polycondensation is less than 5. The molar ratio of the starting components: dicarboxylic acid and glycol in the production o~ the esterification mixture is advantageously rrom 1~ to 1:1,6, 30 At a higher glycol fraction than 1:108 the proce~s becomes increasingly uneconomic and at lower than 1:1,2 a marked prolongation of the ester-ification period has to be tolerated.
:' .
O, Z, 30 J007 ~5~)6~3 The production of the tran3esteri~ication mixture is carried out by conventional methods from a dialkyl ester of terephthalic acid, particularly dimethyl terephthalate and the appropriate ~lycol or glycols. It is generally carried out at atmospheric pressure and at a temperature o~ rrom 130 to 240 C0 It is generally advisable to carry out this reaction quickly and under mlld conditions because otherwise undesirable side reactions such as the formation of di-glycol or possibly of tetrahydrofuran may occur. The molar ratio of dialkyl terephthalate; to glycol is generally from 1:1,2 to 1:2 10 and preferably from 1:102 to 1:1.8. As a rule the lowest possible glycol fraction is chosen so as to keep the cost of the substance used low and to lessen the formation of byproducts~ The transesteri-fication reaction is generally carried out in the presence of ~
Suitable transesterification catalyst such as a zinc, manganese, calcium or titanium compound and the amount added is generally from 0~01 to 0.2% by weight based on dialkyl terephthalate, The trans esterification is generally continued until at least 95% of the total alkoxyl groups present has been eliminated. The transesteri~ication mixture then consist~ mainly o~ diglycol terephthalate and its oligo-20 meric precondensates. The mean degree of polycondensation is con-veniently less than 10, The esterification mixture and the transesterification mixture ~ may be combined immediately a~ter their separate production9 i.e.
; while still hot at temperatures of from 200 to 240C and well ~` mixed. This may be carried out on an industrial scale by means of metering pumps which can be controlled by means of suitable flow meters. Mixing may be carried out by conventional stirring means or static mixers, It is also possible however for the esterification mixture, 30 i.e. the modifying component, to be cooled for example to a temper-' ature of for example 30 to 100C, to be kept in suitable storage vessels and only then to be added to the transesterification mixture, After the esterification mixture has been brought to~ether -, . . ., ~ . . . .
OOZo 303007 ~ 0 5~ ~ 3 with the transesterification mixture the polycondensation is carried out by a conventional method and evacuation to the neccessary reac-tion pressure is carried out before, during or after the heating up period.
Polycondensation of the mixture should also be carried out as mild~y as possible~ i.e. at the lowest possible temperature and in the shortest possible time, in order to lessen the formation of by-products such as diglycol or tetrahydrofuran and to lessen thermal degradation. The polycondensation is accordingly carried out generally at a temperature of from 240 to 290 and preferably at from 250 to 280C and at a pressure of from 760 mm down to Ool mm. The reaction is usually carried out in the presence of a suitable polycondensation catalyst such as an antimony, germanium or titanium compound generally in an amount'of`from OoOl to 0~2% by weight based on the polyester in question and a stabilizer containing phosphorus such as triphenyl phosphate, also in an amount of from OoOl to 002%. Copolyesters having relative viscosities of more than 1.30 and particularly 1.35 (measured in 0.5% by weight solution in a mixture of phenol and o- '' dichlorobenzene in a ratio by weight of 3:2 at 25C in an Ubbel~hde ~`
viscometer) may thus be achieved in rapidly proceeding polyconden~ ;
sation reactions,. ~ ' Modification of polyesber~ may be carried out with great advantages according to the process of the invention; the produc~ion of the ~-~
modifying agent is simple and does not requ~re great expenditure for apparatus, for example in apparatus operated at atmospheric pressure and without the use of a catalyst~ The economical disadvantage of using a large amount of glycol is avoided so that a substantial ~, ;
shortening of the reaction period required for the production of the esterification mixture as modifying agent is possible.
It was not foreseeable that the reaction period for the esteri-~ication o~ aliphatic dicarboxylic acids with aliphatic glycols using a molar ratio o~ from 1:102 to 1:1.8 is only trivially di~ferent when the degree of esterification is 1 mited to from 90 to 95% of the ,' -O.Z~ 30~007 5~ ~ 3 amount of dicarboxylic acid used and that the esterirication mixture o~ monomer and oligomeric glycol esters of dicarboxylic acids can be used for the production of modified polyesters without impairment of product quality or processO
; The esterification mixture of aliphatic dicarboxylic acidQn~ ylyc~l may easily be stored for a long time at slightly elevated temperature without impairment of qualityO Metering the molten modifying agent offers no technical problemsO Contamination o~ the alcohol and glycol distillate with water of reaction is considerably lessened in this 10 method and this is of great advantage because these distillates other-wise can only be supplied for further industrial use with di~ficulty and at great expense. The process according to the invention moreover avoids the formatlon of troublesome deposits and problems in the - polycondensation stage by the water of reaction formedO
- The process may be carried out advantageously batchwise or con-tinuously in conventional polyesker plant.
Polyesters obtained according to the in~ention are distinguished -~
by a low content of byproducts such as diglycol and accordingly ex-hibit good stability. The color of the products is also éxcellent~
Conventional additives such as pigments, antistatic agents, dyes~ glass fibers, stabilizers or fireproofing agents may be incor~
porated before, during orafter the polycondensation in the production of modified polyesters by the process according to the invention~
Modi~ied polyalkylene terephthala~es obtained according ~o the invention may be further processed for exarnple into fibersg fila-ments~ threads, film, sheeting or injection moldings either imme-diately or after conversion into chips cr` the like via a melt.
.. . .,.................................... , :.
Textile moldings even with relatively slight modi~icationg for example with from 5 to 10 mole% of aliphatic dicarboxylic acid, ex-~ hibit a greatly improved dyeing behavior; at a higher content ofaliphatic dicarboxylic acid, ~or example with from 10 to 30 mole%, they may be used for example as bonding `fibers for the production :. - , ~ ' . . . . .
0.~. 30,007 10 ~ ~ 3 of nonwovens. Copolyesters prepared according to the invention and particularly modiried polybutylene terephthalates, may also be used as hot-melt adhesives in the shoe industryO
The following Examples illustrate the inventionO The parts and percentages are by weightO
; (1) PRODUCTION OF THE ESTERIFICATION MIXTURE USED FOR THE
MODIFICATION:
A mixture of 292 parts (2 kmoles) of adipic acid and 186 parts (3 kmoles) of ethylene glycol is heated to 180C within one hour in a stirred vessel which is combined with a packed column having a re-flux divider and a condenser downstream of the same. The water of reaction formed in the esterification is separated from vaporous , entrained ethylene glycol through the rectifying column at a reflux - ratio of 1:1 o The reaction is monitored by determination of the acid ' number of the esteri~ication mixture and with the knowledge of the operating oapacity of the column by the amount o~ distillate. A~ter a reaction perlod o~ three hours at 180C a reaction mixture having a degree o~ esterification of about 93% (based on the free adipic -~
, 20 acid used) has ~ormed in the vessel. `~
CQMPARATIVE EXPERIMENT:
292 parts (2 kmoles) of adipic acid and 248 parts (4 kmoles) o~ ethylene glycol are used ~or the production of the esterif'ication , mixture. I~ a substantially quantitative esterification, i.e. a degree of esterification of about 99%, is required under otherwise the same , conditions, the reaction period at 180 C is about eight hours.
(2) PRODUCTION OF A TRANSESTERIFICATION MIXTURE FROM DIMETHYL ~ ;
TEREPHTHALATE AND ETHYLENE GLYCOL ~
97 parts (0.5 kmole) and 62 parts (1 kmole) of ethylene - `
3 glycol are heated to about 140C with stirring in a heatable stirred vessel with a superposed column ~or separating the methanol liber-ated. 0.03 part of zinc acetate (2H20) and o.o8 parts of antimony acetate dissolved in glycol are then introduced into the homogeneous _g_ O.Z. 30,007 ~ 9 3 melt and the temperature of the reaction mixture is raised in the course o~ three hours to 230C while stirringO The methanol liberated is removed ~rom the system by way of the rectifying column treflux ratio R:D = 3)0 (3) PRODUCTION OF A POLYETHYLENF. TEREPHTHALATE MODIFIED WITH
ADIPIC ACID:
After the transesterification reaction is over 23 9 parts of the esterification mixture prepared according to paragraph (1) is intro-duced into the transesterification mixture at 230C and atmospheric 10 pressure while stirring, stirring is continued for another five minutes and 0.05 part of triphenyl phosphite is added ror stabilization. The stirred reaction mixture is then heated within one hour to 265 to 270C with simultaneous evacuation ~rom 760 mm to less than 1 mm and aftercondensed in this temperature range for about three hours. The finished polycondensate is forced outlunder nitrogen, passed through a ` waterbath, granulated and dried~ A practically colorless product is ; obtained with a relative viscosity of 1043. The material has a ` -so~tening point of about 220C determined microscopi~ally~
20 (1) PRODUCTION OF THE ESTERIFICATION MIXTURE:
An esterification mixture havin~ a degree of esterification of 95% is prepared ~rom 292 parts (2 kmoles) of adipic acid and 270 parts (3 kmoles~ of butanediol~1~4 in a three hour reaction period at 210C in the manner described in Example 1.
(2) PRODUCTION OF A TRANSESTERIFICATION MIXTURE FROM DIMETHYL
TEREPHTHALATE AND BUTANEDIOL-(1,4):
97 parts (0.5 kmoles) of dimethyl terephthalate and 68 parts (0~75 kmole) of butanediol are heated w~ile stirring to about 140C
in a heatable stirred vessel with a superimposed column. 0.1 part of 3 tetrabutyl o-titanate is ~radually introduced into the homogeneous melt and the temperature o~ the reaction mixture is raised to 230C
in the course of two hours with simultaneous stirringO The methanol liberated is removed through the columnO
-lo-.... . i : .
.: .. . . . .
.. :., ,, : . .. . . :
O,Z. ~0,007 1 ~ ~0 ~ ~ 3 (3~ PRODUCTION OF A POLYBUTYLENE TEREPHTHALATE MODIFIED
WITH ADIPIC ACID:
82 parts of the esterification mixture prepared according to paragraph (1) is lntroduced while sti:rring at 230C into the trans-esterification mixture after the reaction is over and stirring is ;
continued for another five minutesO The mixture is then heated to 245 to 250C within one hour while stirring and at the same time evacuating the vessel from 760 mm to less than 1 mm and afterconden-sation is carried on in this temperature range for about three hours.
A substantiall~y colorless polycondensate is obtained which has a relative viscosity of lo 360 The material has a softening point of 10 about 160C determined microscopioallv.
' .~
: : ' - .
.", ' ' .
ADIPIC ACID:
After the transesterification reaction is over 23 9 parts of the esterification mixture prepared according to paragraph (1) is intro-duced into the transesterification mixture at 230C and atmospheric 10 pressure while stirring, stirring is continued for another five minutes and 0.05 part of triphenyl phosphite is added ror stabilization. The stirred reaction mixture is then heated within one hour to 265 to 270C with simultaneous evacuation ~rom 760 mm to less than 1 mm and aftercondensed in this temperature range for about three hours. The finished polycondensate is forced outlunder nitrogen, passed through a ` waterbath, granulated and dried~ A practically colorless product is ; obtained with a relative viscosity of 1043. The material has a ` -so~tening point of about 220C determined microscopi~ally~
20 (1) PRODUCTION OF THE ESTERIFICATION MIXTURE:
An esterification mixture havin~ a degree of esterification of 95% is prepared ~rom 292 parts (2 kmoles) of adipic acid and 270 parts (3 kmoles~ of butanediol~1~4 in a three hour reaction period at 210C in the manner described in Example 1.
(2) PRODUCTION OF A TRANSESTERIFICATION MIXTURE FROM DIMETHYL
TEREPHTHALATE AND BUTANEDIOL-(1,4):
97 parts (0.5 kmoles) of dimethyl terephthalate and 68 parts (0~75 kmole) of butanediol are heated w~ile stirring to about 140C
in a heatable stirred vessel with a superimposed column. 0.1 part of 3 tetrabutyl o-titanate is ~radually introduced into the homogeneous melt and the temperature o~ the reaction mixture is raised to 230C
in the course of two hours with simultaneous stirringO The methanol liberated is removed through the columnO
-lo-.... . i : .
.: .. . . . .
.. :., ,, : . .. . . :
O,Z. ~0,007 1 ~ ~0 ~ ~ 3 (3~ PRODUCTION OF A POLYBUTYLENE TEREPHTHALATE MODIFIED
WITH ADIPIC ACID:
82 parts of the esterification mixture prepared according to paragraph (1) is lntroduced while sti:rring at 230C into the trans-esterification mixture after the reaction is over and stirring is ;
continued for another five minutesO The mixture is then heated to 245 to 250C within one hour while stirring and at the same time evacuating the vessel from 760 mm to less than 1 mm and afterconden-sation is carried on in this temperature range for about three hours.
A substantiall~y colorless polycondensate is obtained which has a relative viscosity of lo 360 The material has a softening point of 10 about 160C determined microscopioallv.
' .~
: : ' - .
.", ' ' .
Claims (9)
1. A process for the production of a modified poly-alkylene terephthalate from the radical of terephthalic acid and the radical of a glycol of two to six carbon atoms in which from 1 to 50 mole % of the terephthalic acid radical has been replaced by an aliphatic dicarboxylic acid radical of four to twelve carbon atoms wherein (a) the said aliphatic dicarboxylic acid is esterified by heating with the said glycol in a molar ratio of from 1:1.2 to 1:1.8 at a temperature of from about 5 to 20°C below the boiling point of the glycol until the degree of esterification is from 90 to 95 mole % based on the aliphatic dicarboxylic acid;
(b) a dialkyl terephthalate is transesterified with the said glycol in a molar ratio of from 1:1.2 to 1:2 in the presence of a catalyst in an amount of from 0.01 to 0.2% by weight base on dialkyl-terephthalate by heating to a temperature of from 130°
to 240°C at atmospheric pressure until at least 95% of the alkoxy groups present have been eliminated; and (c) the esterification product obtained under (a) is mixed with the transesterification product obtained under (b) and polycondensation is carried out at a temperature of from 240 to 290°C and a pressure of from 0.1 to 760 mm, in the presence of a catalyst in an amount of from 0.01 to 0.2% by weight based on the polyester.
(b) a dialkyl terephthalate is transesterified with the said glycol in a molar ratio of from 1:1.2 to 1:2 in the presence of a catalyst in an amount of from 0.01 to 0.2% by weight base on dialkyl-terephthalate by heating to a temperature of from 130°
to 240°C at atmospheric pressure until at least 95% of the alkoxy groups present have been eliminated; and (c) the esterification product obtained under (a) is mixed with the transesterification product obtained under (b) and polycondensation is carried out at a temperature of from 240 to 290°C and a pressure of from 0.1 to 760 mm, in the presence of a catalyst in an amount of from 0.01 to 0.2% by weight based on the polyester.
2. A process as claimed in claim 1, wherein ethylene glycol is used as the glycol.
3. A process as claimed in claim 1, wherein butanediol-1,4 is used as the glycol.
4. A process as claimed in claim 1, wherein from 2 to 40 mole % of the terephthalic radicals are replaced by aliphatic dicarboxylic acid radicals.
5. A process as claimed in claim 1, wherein the aliphatic dicarboxylic acid used is adipic acid.
6. A process as claimed in claim 1, wherein the dialkyl terephthalate used is dimethyl terephthalate.
7. A process as claimed in claim 1, wherein the molar ratio of dicarboxylic acid and glycol in step (a) is from 1:1.3 to 1-1.6.
8. A process as claimed in claim 1, wherein the molar ratio of dialkyl terephthalate to glycol instep (b) is from 1:1.2 to 1:1.8.
9. A process as claimed in claim 1, wherein step (c) is carried out at a temperature of from 250° to 280°C.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DE19732336026 DE2336026C3 (en) | 1973-07-14 | 1973-07-14 | Process for the preparation of modified polyalkylene terephthalates |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1050693A true CA1050693A (en) | 1979-03-13 |
Family
ID=5887013
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA204,585A Expired CA1050693A (en) | 1973-07-14 | 1974-07-11 | Production of modified polyalkylene terephthalates |
Country Status (8)
| Country | Link |
|---|---|
| JP (1) | JPS5039388A (en) |
| BE (1) | BE817613A (en) |
| CA (1) | CA1050693A (en) |
| DE (1) | DE2336026C3 (en) |
| FR (1) | FR2241574B1 (en) |
| GB (1) | GB1466591A (en) |
| IT (1) | IT1017077B (en) |
| NL (1) | NL7409168A (en) |
Families Citing this family (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE2829624A1 (en) * | 1978-07-06 | 1980-01-24 | Basf Ag | THERMOPLASTIC MIXED POLYESTER |
| JPS5665019A (en) * | 1979-11-02 | 1981-06-02 | Toray Ind Inc | Production of polyester |
| AU594068B2 (en) * | 1985-08-08 | 1990-03-01 | B.F. Goodrich Company, The | Poly(vinyl chloride)polyblend containing a crystalline polyester with limited miscibility and reinforced composites thereof |
| DE69006953T2 (en) * | 1989-06-26 | 1994-09-22 | Eastman Kodak Co | Semi-crystalline polyesters, their mixtures with amorphous polyesters and powder coating compositions based on such mixtures. |
| US5135697A (en) * | 1990-08-28 | 1992-08-04 | Hoescht Celanese Corporation | Polyester copolymer fiber having enhanced strength and dyeability properties |
-
1973
- 1973-07-14 DE DE19732336026 patent/DE2336026C3/en not_active Expired
-
1974
- 1974-07-05 NL NL7409168A patent/NL7409168A/en not_active Application Discontinuation
- 1974-07-10 FR FR7423974A patent/FR2241574B1/fr not_active Expired
- 1974-07-11 IT IT2505574A patent/IT1017077B/en active
- 1974-07-11 CA CA204,585A patent/CA1050693A/en not_active Expired
- 1974-07-12 GB GB3091174A patent/GB1466591A/en not_active Expired
- 1974-07-12 BE BE146524A patent/BE817613A/en not_active IP Right Cessation
- 1974-07-15 JP JP8030374A patent/JPS5039388A/ja active Pending
Also Published As
| Publication number | Publication date |
|---|---|
| DE2336026B2 (en) | 1975-10-30 |
| JPS5039388A (en) | 1975-04-11 |
| BE817613A (en) | 1975-01-13 |
| FR2241574A1 (en) | 1975-03-21 |
| IT1017077B (en) | 1977-07-20 |
| GB1466591A (en) | 1977-03-09 |
| DE2336026C3 (en) | 1980-09-25 |
| FR2241574B1 (en) | 1978-01-20 |
| DE2336026A1 (en) | 1975-02-13 |
| NL7409168A (en) | 1975-01-16 |
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