CA1080394A - Process for preparing polyesters of butane-1,4-diol - Google Patents
Process for preparing polyesters of butane-1,4-diolInfo
- Publication number
- CA1080394A CA1080394A CA203,413A CA203413A CA1080394A CA 1080394 A CA1080394 A CA 1080394A CA 203413 A CA203413 A CA 203413A CA 1080394 A CA1080394 A CA 1080394A
- Authority
- CA
- Canada
- Prior art keywords
- butane
- diol
- condensation
- reaction
- 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
Links
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
Abstract
Process for preparing Polyesters of butane-1,4-diol Abstract of the Disclosure A process for the preparation of polyesters from butane-1,4-diol and at least one aromatic dicarboxylic acid in which the butane-1,4-diol is condensed with the acid in the melt and in the presence of at least one dimethyl ester of the dicarboxylic acid used.
Description
lO~V~
This invention relates to a process for preparing polyesters by reacting terephthalic acid and butane-1,4-diol in the presence of the dimethyl ester of the dicarboxylic acid used.
It is known that polytetramethylene esters can be made by ester interchange of dimethyl esters of aromatic dicarboxylic acids with butanediol to form the corresponding glycol esters which are then subjected to poly-condensation. This method has numerous disadvantages: at the high conden-sation temperatures, the butane-1,4-diol gives rise to large quantities of tetrahydrofuran which distils over with the excess butane-1,4-diol. The butane-1,4-diol recovered from the process is therefore contaminated and cannot be used again directly.
It is also known to react the free dicarboxylic acid with butane-l, 4-diol, but if one wants good yields this method requires very high conden-sation temperatures and applied pressure. A considerable proportion of the butanediol is therefore again converted into tetrahydrofuran which leads to the difficulties already mentioned above. In addition, very long condensation times are required. It is therefore a matter of great economic interest to ; develop a special proceeding which avoids one step of the process and the above mentioned disadvantages, especially the long condensation times, by means of using the nonesterified aromatic dicarboxylic acids.
It has unexpectedly been found that the condensation times can considerably be decreased by means of the addition of a dimethyl ester of the dicarboxylic acid used. One skilled in the art should have expected that the dimethyl ester should preferably be esterified by ester interchange because of its good solubility in butane-1,4-diol and its higher reactivity, and that therefore it should not be able to exercise an accelerating influence on the , reaction after a short time.
- This invention therefore relates to a process for the preparation of linear high-molecular weight polyesters by catalytic reaction of butane-l, 4-diol with an aromatic dicarboxylic acid, namely terephthalic acid, by the ,, , -1- qF .
`~ D
108V39~
31t condensation proccSs, wh~ch ;s characterised in that the reaction is carried ou~ in the presence of 5 - 20 percent by weight, based on the amount of the dicarboxylic acid of the dimethyl ester of the dicarboxylic acid used, i.e. of dimethyl terephthalate.
The process according to the invention may be carried out continuously or intermittently, generally between 160 and 200C. 1,05 to
This invention relates to a process for preparing polyesters by reacting terephthalic acid and butane-1,4-diol in the presence of the dimethyl ester of the dicarboxylic acid used.
It is known that polytetramethylene esters can be made by ester interchange of dimethyl esters of aromatic dicarboxylic acids with butanediol to form the corresponding glycol esters which are then subjected to poly-condensation. This method has numerous disadvantages: at the high conden-sation temperatures, the butane-1,4-diol gives rise to large quantities of tetrahydrofuran which distils over with the excess butane-1,4-diol. The butane-1,4-diol recovered from the process is therefore contaminated and cannot be used again directly.
It is also known to react the free dicarboxylic acid with butane-l, 4-diol, but if one wants good yields this method requires very high conden-sation temperatures and applied pressure. A considerable proportion of the butanediol is therefore again converted into tetrahydrofuran which leads to the difficulties already mentioned above. In addition, very long condensation times are required. It is therefore a matter of great economic interest to ; develop a special proceeding which avoids one step of the process and the above mentioned disadvantages, especially the long condensation times, by means of using the nonesterified aromatic dicarboxylic acids.
It has unexpectedly been found that the condensation times can considerably be decreased by means of the addition of a dimethyl ester of the dicarboxylic acid used. One skilled in the art should have expected that the dimethyl ester should preferably be esterified by ester interchange because of its good solubility in butane-1,4-diol and its higher reactivity, and that therefore it should not be able to exercise an accelerating influence on the , reaction after a short time.
- This invention therefore relates to a process for the preparation of linear high-molecular weight polyesters by catalytic reaction of butane-l, 4-diol with an aromatic dicarboxylic acid, namely terephthalic acid, by the ,, , -1- qF .
`~ D
108V39~
31t condensation proccSs, wh~ch ;s characterised in that the reaction is carried ou~ in the presence of 5 - 20 percent by weight, based on the amount of the dicarboxylic acid of the dimethyl ester of the dicarboxylic acid used, i.e. of dimethyl terephthalate.
The process according to the invention may be carried out continuously or intermittently, generally between 160 and 200C. 1,05 to
2,4 moles, preferably 1,1 to 1,4 moles of butane-1,4-diol, are used per 1 mole of (dicarboxylic acid I dicarboxylic acid dimethyl ester). Accord-ing to a preferred method of carrying out the process, the starting components are heated to not more than 200C in the first condensation stage and kept at this temperature until all the volatile decomposition products, as well as free butanediol, have distilled off~ This first condensation stage is preferably carried out at an applied pressure of 4 - 5 excess atmospheres. The second stage of condensation may be carried out in known manner under vacuum at temperatures of between 250C and 310C.
Both the first and the second stage of condensation are preferably carried out in the presence of catalysts. Known esterific-; ation catalysts such as compounds of zinc, manganese, cobalt, lead and calcium and of the alkali metals may be used for accelerating the firststage of condensation. Phosphoric acid, phosphorous acid or alkyl, aryl or alkylaryl esters of phosphoric acid are then added to the reaction mixture to inhibit these catalysts after termination of the first stage of condensation and to increase the stability of the end products. The polycondensation process is catalysed with titanium compounds which may be used together with other known polycondensation catalysts. Tetratitanic acid esters are preferred, e.g. tetraisopropyl titanate.
The polytetramethylene esters obtained according to the invention are distinguished by their high viscosity. In addition, they are thermally stable and undergo only a negligable decrease in iO~3039~
viscosity on prolonged heating in the melt.
The following Examples illustrate the invention:
~ D
.`, . ~. . .
~ 1080394 Example 1 2,700 g of terephthalic acid and 300 g of dimethyl terephthalate are mixed with 2,800 g butane-1,4-diol in a 20 litre autoclave, and 0.1 % by weight (3 g) of sodium acetate is added as esterification catalyst. The mixture is heated to a temperature of 200C and kept at this temper-ature for 3.5 hours at an applied pressure of 4 - 5 excess atmospheres. At the same time, methanol, water and tetra-hydrofuran are continuously distilled off. The reaction mix-ture is then heated to 220C and the excess pressure is re-leased after 1 hour. After the addition of 0.05 % by weight of tetraisopropyl titanate ~1.5 g), the temperature is raised to 265C and condensation is continued at a pressure of 1 Torr. After about 2 hours, the product has reached a vis-cosity of 2200 Poises and is spun off. The resulting pro-duct has the following properties:
n 280 C = 2200 Poises 250C = 5400 Poises Mp = 224 - 225C
Reflection (460 nm) = 68.5 %
Example 2 The procedure is the same as in example 1 except that the reaction is carried out without the addition of di-methyl terephthalate. Only a low viscosity material with a viscosity of ~ = 15 Poises at 280C is obtained after a reaction time of 6.5 hours.
Example 3 '~ Condensation is carried out as described in example 1 except that the quantity of dimethyl terephthalate is reduced to 5 % by weight, based on the dicarboxylic acid. The poly-. :
lO~V3~
ester then obtained as a viscosity of n 280C = 2000 Poises Its melting point is 225C and its reflection (460 nm) is 70 %.
Example 4 Condensation is carried out as described in example 1 ex-cept that the quantity of butane-1,4-diol is reduced to 1950 g.
The polyester ~hen obtained has a viscosity of ~ 280C = 2800 Poises. Its reflection (460 nm) is 82 %.
Example 5 The reaction may also be carried out continuously. In - -that case, instead of adding dimethyl terephthalate, a reserve -sump-is used (90 - 40 %) into which a paste of terephthalic acid and butanediol (10 bis 60 percent by weight; proportion by weight of terephthalic acid : butanediol = 1 : 0.7 to 1 : 3) heated to a temperature of 150C is continuously introduced. For this purpose it is suitable to use a pressure-operated overflow cas-cade into the first stage of which is introduced the above mentioned suspension at a temperature of 220C. The est~rified material can be continuously discharged from the 8th stage (eight chamber container with 20 litre capacity; throughput 20,000 - 25,000 g per hour) and continuously conveyed to a ~ -polycondensation apparatus (two-shaft reactor). The reaction ~ -is carried out at a steam pressure of 4 excess atmospheres.
The catalysts are continuously added with the suspension of terephthalic acid and butanediol (sodium acetate and ti- -tanium tetraisopropylate as indicated under 1). The eight-chamber container (cascade) is advantageously arranged as a back-flow assembly in which from the 7th chamber onwards 10 -30 % of the esterification mixture is pumped into the first chamber where it is reacted with the paste of terephthalic acid and butanediol.
.. . . . .. . . . . .
Both the first and the second stage of condensation are preferably carried out in the presence of catalysts. Known esterific-; ation catalysts such as compounds of zinc, manganese, cobalt, lead and calcium and of the alkali metals may be used for accelerating the firststage of condensation. Phosphoric acid, phosphorous acid or alkyl, aryl or alkylaryl esters of phosphoric acid are then added to the reaction mixture to inhibit these catalysts after termination of the first stage of condensation and to increase the stability of the end products. The polycondensation process is catalysed with titanium compounds which may be used together with other known polycondensation catalysts. Tetratitanic acid esters are preferred, e.g. tetraisopropyl titanate.
The polytetramethylene esters obtained according to the invention are distinguished by their high viscosity. In addition, they are thermally stable and undergo only a negligable decrease in iO~3039~
viscosity on prolonged heating in the melt.
The following Examples illustrate the invention:
~ D
.`, . ~. . .
~ 1080394 Example 1 2,700 g of terephthalic acid and 300 g of dimethyl terephthalate are mixed with 2,800 g butane-1,4-diol in a 20 litre autoclave, and 0.1 % by weight (3 g) of sodium acetate is added as esterification catalyst. The mixture is heated to a temperature of 200C and kept at this temper-ature for 3.5 hours at an applied pressure of 4 - 5 excess atmospheres. At the same time, methanol, water and tetra-hydrofuran are continuously distilled off. The reaction mix-ture is then heated to 220C and the excess pressure is re-leased after 1 hour. After the addition of 0.05 % by weight of tetraisopropyl titanate ~1.5 g), the temperature is raised to 265C and condensation is continued at a pressure of 1 Torr. After about 2 hours, the product has reached a vis-cosity of 2200 Poises and is spun off. The resulting pro-duct has the following properties:
n 280 C = 2200 Poises 250C = 5400 Poises Mp = 224 - 225C
Reflection (460 nm) = 68.5 %
Example 2 The procedure is the same as in example 1 except that the reaction is carried out without the addition of di-methyl terephthalate. Only a low viscosity material with a viscosity of ~ = 15 Poises at 280C is obtained after a reaction time of 6.5 hours.
Example 3 '~ Condensation is carried out as described in example 1 except that the quantity of dimethyl terephthalate is reduced to 5 % by weight, based on the dicarboxylic acid. The poly-. :
lO~V3~
ester then obtained as a viscosity of n 280C = 2000 Poises Its melting point is 225C and its reflection (460 nm) is 70 %.
Example 4 Condensation is carried out as described in example 1 ex-cept that the quantity of butane-1,4-diol is reduced to 1950 g.
The polyester ~hen obtained has a viscosity of ~ 280C = 2800 Poises. Its reflection (460 nm) is 82 %.
Example 5 The reaction may also be carried out continuously. In - -that case, instead of adding dimethyl terephthalate, a reserve -sump-is used (90 - 40 %) into which a paste of terephthalic acid and butanediol (10 bis 60 percent by weight; proportion by weight of terephthalic acid : butanediol = 1 : 0.7 to 1 : 3) heated to a temperature of 150C is continuously introduced. For this purpose it is suitable to use a pressure-operated overflow cas-cade into the first stage of which is introduced the above mentioned suspension at a temperature of 220C. The est~rified material can be continuously discharged from the 8th stage (eight chamber container with 20 litre capacity; throughput 20,000 - 25,000 g per hour) and continuously conveyed to a ~ -polycondensation apparatus (two-shaft reactor). The reaction ~ -is carried out at a steam pressure of 4 excess atmospheres.
The catalysts are continuously added with the suspension of terephthalic acid and butanediol (sodium acetate and ti- -tanium tetraisopropylate as indicated under 1). The eight-chamber container (cascade) is advantageously arranged as a back-flow assembly in which from the 7th chamber onwards 10 -30 % of the esterification mixture is pumped into the first chamber where it is reacted with the paste of terephthalic acid and butanediol.
.. . . . .. . . . . .
Claims
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A process for the preparation of linear high-molecular weight polytetramethylene esters by catalytic reaction of butane-1,4-diol with terephthalic acid by the melt condensation process, characterised in that the reaction is carried out in the presence of 5 - 20 percent, based on the amount of dicarboxylic acids, by weight of dimethyl terephthalate.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DE19732332566 DE2332566A1 (en) | 1973-06-27 | 1973-06-27 | PROCESS FOR THE PRODUCTION OF POLYESTERS OF 1,4-BUTANEDIOL |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1080394A true CA1080394A (en) | 1980-06-24 |
Family
ID=5885169
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA203,413A Expired CA1080394A (en) | 1973-06-27 | 1974-06-25 | Process for preparing polyesters of butane-1,4-diol |
Country Status (9)
| Country | Link |
|---|---|
| JP (1) | JPS5037891A (en) |
| BE (1) | BE816886A (en) |
| CA (1) | CA1080394A (en) |
| CH (1) | CH590306A5 (en) |
| DE (1) | DE2332566A1 (en) |
| FR (1) | FR2237923B1 (en) |
| GB (1) | GB1432284A (en) |
| IT (1) | IT1016142B (en) |
| NL (1) | NL7408468A (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE2514116C3 (en) * | 1975-03-29 | 1983-03-17 | Basf Ag, 6700 Ludwigshafen | Process for the continuous production of linear, high molecular weight polybutylene terephthalates |
Family Cites Families (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CA1079895A (en) * | 1973-02-28 | 1980-06-17 | General Electric Company | Production of polyesters |
-
1973
- 1973-06-27 DE DE19732332566 patent/DE2332566A1/en active Pending
-
1974
- 1974-06-24 NL NL7408468A patent/NL7408468A/xx not_active Application Discontinuation
- 1974-06-24 IT IT5168174A patent/IT1016142B/en active
- 1974-06-25 CA CA203,413A patent/CA1080394A/en not_active Expired
- 1974-06-25 CH CH868674A patent/CH590306A5/xx not_active IP Right Cessation
- 1974-06-25 JP JP7193574A patent/JPS5037891A/ja active Pending
- 1974-06-26 GB GB2833374A patent/GB1432284A/en not_active Expired
- 1974-06-26 BE BE145906A patent/BE816886A/en unknown
- 1974-06-27 FR FR7422505A patent/FR2237923B1/fr not_active Expired
Also Published As
| Publication number | Publication date |
|---|---|
| IT1016142B (en) | 1977-05-30 |
| GB1432284A (en) | 1976-04-14 |
| DE2332566A1 (en) | 1975-01-16 |
| JPS5037891A (en) | 1975-04-08 |
| FR2237923A1 (en) | 1975-02-14 |
| CH590306A5 (en) | 1977-08-15 |
| BE816886A (en) | 1974-12-27 |
| NL7408468A (en) | 1974-12-31 |
| FR2237923B1 (en) | 1978-01-13 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |