BE878249A - PROCESS FOR THE PREPARATION OF POLYESTERS OF GLYCOLS AND DICARBOXYLIC ACIDS - Google Patents

Description

       

  DESCRIPTIVE MEMORY

  
in support of a request for

PATENT

  
for

  
"Process for the preparation of polyesters of glycols and acids

  
 <EMI ID = 1.1>

  
2 ulitsa Bebelya, 26, kv. 139,

MOSCOW (U.R.S.S.),

  
 <EMI ID = 2.1>

  
naberezhnaya M. Gorkogo, 4/22, korpus B, kv.46, MOSCOW (U.R.S.S.),

  
 <EMI ID = 3.1>

  
2 Pugachevskaya ulitsa, 8, korpus 5, kv.10, MOSCOW (U.R.S.S.),

  
 <EMI ID = 4.1>

  
\ 5) Efimovich NOSOVSKY Jury,

  
Volzhsky bulvar, 43, kv. 44,

MOSCOW (U.K.S.S.),

  
6) Mikhail Vladimirovich VISHNYAXOV,

  
Shelepikhinskaya naberezhnaya, 8, korpus 2, kv.85, MOSCOW (U.R.S.S.),

  
7) Vladimir Sergeevich SCHER3AKCV,

  
Lesnaya ulitsa, 8, kv.58,

  
 <EMI ID = 5.1> The present invention relates to processes for obtaining polyesters and in particular relates to a process for the preparation of polyesters of glycols and of dicarboxylic acids by transesterification of dialkyl esters of dicarboxylic acids with glycols. The reaction products are mainly used as plasticizers for various polymers, preferably for

  
polyvinyl chloride, nitrocellulose, ethylcellulose, rubber. They are also used in rubber mastic for the manufacture of cables, in the production

  
linoleum, gas and oil resistant piping for tractors and cars, gaskets for refrigerators, etc.

  
It is known that obtaining polyesters by transesterification in the absence of catalyst is practically not possible.

  
Manganese salts, oxides and alcoholates are known as transesterification catalysts,

  
zinc, cobalt, antimony, titanium, germanium and tin (see V.V. Korshak, S.V. Vinogradova. "Polycondensation

  
 <EMI ID = 6.1>

  
However, these catalysts are insufficiently effective.

  
An attempt to apply a binary catalyst in which the chosen constituents would mutually reinforce did not lead to positive results (see L.B. Sokolov. "The method of synthesis of polymers by

  
 <EMI ID = 7.1>

  
A process for the preparation of polyesters is known

  
of glycols and dicarboxylic acids by transesterification of dialkyl esters of dicarboxylic acids with glycols, at a temperature of 130 to 190 [deg.] C and under a residual pressure of 200 to 100 mm of Hg, in the presence of a catalytic system consisting of activated carbon mixed with zinc acetate or an organotin compound corresponding to the general formula
 <EMI ID = 8.1>
 in which R - C11H23 or C9H19

  
(see Author's certificate of the USSR N [deg.] 311930, cl. C08 g,
63/16).

  
However, the duration of the synthesis of polyesters with the indicated catalytic systems is relatively large, in particular 15-17 hours. In addition, when using

  
 <EMI ID = 9.1>

  
strongly colored polyesters are obtained, ranging from yellow to dark brown. By using organotin compounds mixed with activated carbon, polyesters which are unstable to hydrolytic destruction are obtained, and only additional treatment with zinc acetate ensures their stability.

  
during storage.

  
The object of the present invention is to eliminate the drawbacks indicated.

  
We therefore proposed, in the preparation process

  
 <EMI ID = 10.1>

  
on the transesterification of dialkyl esters of dicarboxylic acids, to choose a catalytic system which would reduce the duration of the process and improve the quality of the finished products.

  
The solution consists in a process for the preparation of polyesters of glycols and of dicarboxylic acids by transesterification of dialkyl esters of dicarboxylic acids with glycols, at a temperature of 150 to 250 [deg.] C and under

  
 <EMI ID = 11.1>

  
2 mm Hg, in the presence of a catalytic system consisting of an organometallic compound and activated carbon, said process being characterized according to the invention, in that the organometallic compound used is tetrabutoxytitane in a tetrabutoxytitanium-carbon weight ratio active from 0.004: 1 to 0.05: 1, preferably from 0.008: 1 to 0.009: 1, respectively, the amount of the catalyst system being from 0.2 to 10%, preferably from 1.5 to 2.5% , of the weight of the dialkyl esters of starting dicarboxylic acids.

  
The limiting quantities of the catalytic system described with respect to the weight of the starting dialkyl esters are a function of the duration of the process, of the coloring of the polyesters obtained and of their stability to hydrolytic destruction. In fact, the use of the catalytic system in an amount greater than 10% of the weight of the starting esters results in a considerable deterioration in the coloration of the polyesters (more than N [deg.] 5 according to the iron scale). copper-cobalt) and in the case of a catalytic system content of less than 0.2% relative to the weight of the esters, the duration

  
of the process increases and its degree of completion (i.e. the conversion rate) decreases.

  
The use of the catalytic system recommended by the invention, consisting of tetrabutoxytitanium and activated carbon, makes it possible to reduce the duration of the process from 1.5 to 3 times. In addition, the use of the indicated catalytic system makes it possible to obtain practically uncolored polyesters, their color corresponding to N [deg.] S 2 and 3 according to the scale with iron-copper-cobalt. The polyesters synthesized in the presence of the catalytic system according to the invention have a sufficiently high stability during storage (the values of the acid number after storage of the polyesters for 6 months under the conditions of a humidity of 98% do not not exceed

  
2 mg KOH / g).

  
Polyesters of glycols and dicarboxylic acids are obtained by transesterification of dialkyl esters of dicarboxylic acids or their mixtures with glycols or with mixtures thereof. It is possible to use as dialkyl esters of carboxylic acids various esters of acids of the aliphatic series and of the aromatic series, such as adipic, sebacic, phthalic acid, as well as

  
aliphatic mono-atomic alcohols such as' -'methyl alcohol, butyl alkocl. Among the glycols, it is possible to choose, for example, ethylene glycol, diethylene glycol, butane-diol-1,4, dimethyl-2,2-propane-diol-'1,3 (neopentyl-glyuol). Synthesis takes place at a temperature

  
from 150 to 250 [deg.] C and under a pressure of 760 mm of Hg up to a residual pressure of 2 mm of Hg.

  
Other characteristics and advantages of the invention will be better understood on reading the description, which will follow, of several concrete but non-limiting exemplary embodiments.

Example 1.-

  
In a three-necked glass flask fitted with a rectification column, a refrigerant system and a receiver for the secondary product released during

  
of the reaction, in particular butanol, 300 g (1.16 mole) of dibutyl ester of adipic acid, 92.4 g (0.87 mole) of diethylene glycol, 0.01 g of tetrabutoxytitane and 0 , 59 g

  
activated carbon. The ratio of tetrabutoxytitanium to activated carbon is 0.017: 1, the amount of catalytic system relative to the weight of the dibutyl ester of adipic acid is equal to 0.2%. The agitator and the heater are started. At a reaction mass temperature of 180 to 190 [deg.] The pressure in the system is lowered to 560-460 mm Hg of residual pressure. As the distillation of the butanol weakens, the residual pressure is lowered to 20-10 mm of Hg and gradually raised

  
the temperature at 200 [deg.] C. The transesterification is carried out under the conditions indicated until the butanol distillation is completed. The hydroxyl number then reaches

  
 <EMI ID = 12.1>

  
In Table 1 below are given the characteristics of the polyester obtained according to Example 1 and the characteristics which the same polyester must have according to the standardized requirements.

  
Table 1.

  

 <EMI ID = 13.1>
 

  

 <EMI ID = 14.1>

Example 2.-

  
300 g (1.16 mole) of ester are placed in a three-necked glass flask fitted with a rectification column, a refrigerant system and a butanol receiver released during the reaction. dibutylic adipic acid, 92.4 g (0.87 mole) of diethylene glycol, 0.12 g of tetrabutoxytitane and 29.88 g of activated carbon. The tetrabutoxytitanium / activated carbon ratio is 0.004: 1,

  
 <EMI ID = 15.1>

  
the dibutyl ester of adipic acid is 10%. The agitator and the heater are started. At the temperature of 195 [deg.] C the pressure in the system is reduced to a residual pressure of 560 to 460 mm of Hg. As the distillation of butanol decreases, the residual pressure is lowered up to 20-10 mm Hg, and the temperature is gradually raised to 210 [deg.] C. We perform

  
transesterification. under the conditions indicated until the butanol distillation ceases and until the hydroxyl number is equal to 0.1%.

  
The duration of the synthesis is 10 hours.

  
The characteristics of the polyester obtained according to Example 2 and those which the same polyester must have according to the standardized requirements are given below.

  
Table 2

  

 <EMI ID = 16.1>

Example 3.-

  
In a three-necked glass flask fitted with a rectification column, a cooling system and a receiver for the butanol released during the reaction, 300 g (1.16 mol) of dibutyl ester of adipic acid, 92.4 g (0.87 mole) of diethylene glycol, 0.13 g of tetrabutoxytitane and 14.87 g of activated carbon.

  
The tetrabutoxytitanium / activated carbon ratio is equal to 0.0087: 1, the amount of catalytic system relative to the weight of the dibutyl ester of adipic acid is 5%. The agitator and the heater are started. When the reaction mass reaches the temperature of 180 [deg.] C the pressure in the system is lowered to a pressure

  
 <EMI ID = 17.1>

  
the weakening of the butanol distillation we lower

  
 <EMI ID = 18.1>

  
 <EMI ID = 19.1>

  
transesterification under the conditions indicated until the butane distillation ceases! and until

  
 <EMI ID = 20.1>

  
,, 1 The synthesis lasts 7 hours.

  
In Table 3 below are summarized the characteristics of the polyester prepared according to Example 3 and those which it must have according to the standardized requirements.

  
Table 3

  

 <EMI ID = 21.1>

Example 4.-

  
135 g (0.52 mole) of dibutyladipate are placed in a three-necked glass flask fitted with a rectification column, a refrigerant system and a butanol receiver released during the reaction. , 165 g
(0.52 mole) of dibutylsébaçate, 92.4 (0.87 mole) of diethylene glycol, 0.05 g of tetrabutoxytitane and 6 g of activated carbon. The tetrabutoxytitanium: activated carbon ratio

  
 <EMI ID = 22.1>

  
turns on the agitator and the heater. When the reaction mass reaches the temperature of 180 [deg.] C, we lower

  
the pressure in the system to a residual pressure of 560 to 460 mm of Hg. As the distillation of butanol weakens, the residual pressure is lowered to 20-10 mm of Hg and gradually raises the temperature of the reaction mass to 200-210 [deg.] C. The transesterification is carried out under the conditions indicated, until the ceasing of the distillation of butanol and until the hydroxyl number is 0.25%. The duration of the synthesis is 9 hours.

  
In Table 4 below, the characteristics of the polyester obtained according to Example 4 are given and the characteristics which the same polyester must have according to

  
standard requirements.

  
Table 4

  

 <EMI ID = 23.1>

Example 5.-

  
The process is carried out in a unit comprising a vertical cylindrical stainless steel reactor with a capacity of 3.2 m <3>, equipped with a propeller agitator and an internal coil for heating and cooling the reaction mass, a reaction column, refrigerants and butanol receptors released during the reaction.

  
1600 kg of dibutyladipate are placed in the reactor,
430 kg of diethylene glycol, 0.3 kg of tetra, outoxytitanium and
30 kg of activated carbon. The ratio of tetrabutoxytitanium to activated carbon is 0.01: 1, the amount of catalytic system relative to the weight of dibutyladipate is

  
4 1.89%. After loading the reagents, we carry the mass

  
 <EMI ID = 24.1>

  
temperature and at atmospheric pressure (760 mm Hg) begins the distillation of the butanol released during the reaction, said distillation weakening when

  
 <EMI ID = 25.1>

  
gradually decreases the pressure in the system to a residual pressure of 40 to 30 mm Hg, and the process continues under this pressure and at a temperature of
180-190 [deg.] C until the distillation of butanol stops and until

  
 <EMI ID = 26.1>

  
hours. In Table 5 below, the characteristics of the polyester obtained according to Example 5 are given and those which the same polyester must have according to the standardized requirements.

  
Table 5

  

 <EMI ID = 27.1>

Example 6.-

  
The synthesis is carried out in a unit identical to that described in Example 5. It is charged to the reactor
700 kg of dibutyladipate, 852 kg of dibutylsébaçate, 448 kg of diethylene glycol, 0.3 kg of tetrabutoxytitanium and 30 kg

  
f of activated carbon. The ratio of tetrabutoxytitanium to activated carbon is 0.01: 1, the amount of catalytic system

  
relative to the total weight of the initial diesters is equal

  
at 1.95%. The loading of the constituents finished, we carry

  
the reaction mass up to a temperature of 180 to 190 [deg.] C. At this temperature and under atmospheric pressure, the distillation of the butanol which is released during the reaction begins. As the butanol distillation weakens, the pressure in the system is gradually lowered to a residual pressure of
40 to 30 mm Hg. Transesterification continues at the indicated residual pressure and at a temperature of 180 to
190 [deg.] C until the distillation of butanol stops and

  
 <EMI ID = 28.1>

  
 <EMI ID = 29.1>

  
 <EMI ID = 30.1>

  
of the polyester obtained according to Example 6 and those which the same polyester must have according to the standardized requirements.

  
Table 6.

  

 <EMI ID = 31.1>
 

Example 7.-

  
In a three-necked glass flask fitted with a rectification column, a cooling system and a receiver for the butanol released during the reaction, 300 g (1.16 mol) of dibutyl ester of adipic acid, 90.7 g (0.87 mole) of dimethyl-2,2-propanediol-1,3, 0.05 g of tetrabutoxytitane and 6 g of activated carbon. The tetrabutoxytitanium / activated carbon ratio is 0.0083: 1, the amount of catalytic system relative to the weight of dibutyladipate is 2%. The agitator and the heating system are started.

   When the reaction mass reaches a temperature of 170 to 180 [deg.] C, the pressure in the system is lowered to a residual pressure of 660 to 560 mm of Hg, As the distillation of the butanol the residual pressure is lowered to 20-10 mm Hg and the temperature is gradually raised to 200 [deg.] C. The transesterification is carried out under the conditions indicated, until the distillation of butanol ceases and the hydroxyl number is 0.17%. The synthesis lasts 8 hours. A similar synthesis is made for comparison, with the difference that a mixture of zinc acetate and activated carbon is used as the catalytic system (USSR author's certificate N [deg.] 311930). The synthesis lasts 17 hours.

  
The characteristics of the polyesters obtained according to Example 7 and according to the USSR author's certificate N [deg.] 311930 are summarized in Table 7.

  
Table 7.

  

 <EMI ID = 32.1>
 

Example 8.-

  
300 g (1.16 mole) of dibutyladipate are placed in a three-necked glass flask fitted with a rectification column, a cooling system and a butanol receptor released during the reaction. , 45.6 g
(0.43 mole) of diethylene glycol, 26.7 g (0.43 mole) of ethylene glycol, 0.03 g of tetrabutoxytitane and 3.17 g of activated carbon. The tetrabutoxytitanium / activated carbon ratio is 0.0095: 1, the amount of catalytic system relative

  
the weight of dibutyladipate is 8%. After loading the components, the pressure in the system is lowered to
560-460 mm of Hg and the reaction mass is brought to the temperature of 150 [deg.] C. As the distillation of the butanol weakens, the temperature of the reaction mass is raised to 250 [deg.] C and the residual pressure is lowered to 10-2 mm Hg. transesterification under the conditions indicated, until the distillation of butanol ceases and the hydroxyl number of the reaction mass is equal to 0.17%. The synthesis lasts 7 hours.

  
A polyester is obtained having the following characteristics:

  

 <EMI ID = 33.1>

Example 9.-

  
In a three-necked glass flask fitted with a rectification column, a cooling system and a receiver for the butanol released during the reaction, 300 g (1.16 mole) of dibutyladipate, 53.4 g
(0.86 mole) of ethylene glycol, 0.02 g of tetrabutoxytitanium and 1.48 g of activated carbon. The tetrabutoxytitanium / activated carbon ratio is 0.014: 1, the amount of catalytic system relative to the weight of dibutyladipate is 0.5%. The loading of the reagents finished, the pressure in the system is lowered to 560-460 mm of Hg and the reaction mass is brought to 160 [deg.] C. As the distillation of butanol weakens, the residual pressure in the system is lowered to 2 mm Hg and the temperature is raised to 250 [deg.] C.

   The transesterification is carried out under the conditions indicated, until the distillation of the butanol ceases and the hydroxyl number of the reaction mass is 0.15%. The synthesis lasts 8 hours.

  
The result is a polyester having the following characteristics:

  

 <EMI ID = 34.1>

Example 10.-

  
In a three-necked glass flask fitted with a rectification column, a refrigerant system and

  
of a butanol receptor released during the reaction, 300 g (1.16 mol) of dibutyladipate, 79.2 g are placed
(0.88 mole) of 1,4-butane diol, 0.3 g of tetrabutoxytitanium and 6 g of activated carbon. The tetrabutoxytitanium / activated carbon ratio corresponds to 0.05: 1, the amount of catalytic system relative to the weight of dibutyladipate is 2.1%. The loading of the reagents finished, the reaction mass is heated to 180 [deg.] C. At this temperature and under atmospheric pressure (760 mm Hg), the distillation of butanol begins.

  
As the butanol distillation weakens, the pressure in the system is lowered to 5 mm Hg and the temperature is gradually raised to 230 [deg.] C.

  
The transesterification is carried out under the conditions indicated, until the distillation of the butanol ceases and the hydroxyl number is 0.08%. The synthesis lasts 6 hours.

  
A polyester is obtained having the following characteristics:

  

 <EMI ID = 35.1>


  
By comparing the examples cited with those described in the author's certificate of the USSR N [deg.] 311930 we can see that the use of the catalytic system constituted by a mixture

  
of tetrabutoxytitanium and activated carbon makes it possible to reduce the duration of the process from 1.5 to 3 times compared with the catalytic system zinc acetate-activated carbon and the catalytic system dibutyltin-dicaprylate-activated carbon.

  
It should also be noted that the use of the catalytic system according to the invention gives a very marked synergistic effect of the catalytic action. This is confirmed by the fact that when active carbon is used in admixture with tetrabutoxytitane, the reaction rate constant increases from 1.5 to 2 times compared to the reaction rate constant in the presence of tetrabutoxytitane as catalyst.

  
On the other hand, when active carbon is used as a catalytic system in admixture with other compounds, in particular zinc acetate or dibutyletair.dicaprylate
(USSR author's certificate N [deg.] 311930), the reaction rate constant decreases compared to the reaction rate constant obtained in the presence of only zinc acetate or only dibutyltin dicaprylate.

  
In table 8 are given for comparison the values of the transesterification rate constants

  
dibutyl ester of adipic acid by diethylene glycol at a temperature of 170 [deg.] C in the presence of known catalytic systems used in the production of industrial brands of polyesters, in the presence of constituents of said catalytic systems taken individually, as well as 'in the presence of the catalytic system according to the invention.

  

 <EMI ID = 36.1>


  
Of course, the invention is in no way limited to the embodiments described which have not been

  
given as an example. In particular, it includes all the means constituting technical equivalents of the means described as well as their combinations if these are carried out according to the spirit and implemented in the context of the claims which follow.

CLAIMS

  
1.- Process for the preparation of polyesters of glycols and dicarboxylic acids by transesterification of dialkyl esters of dicarboxylic acids with glycols, at a temperature of 150 to 250 [deg.] C and under pressure of 760 mm of Hg up to '' at a residual pressure of 2 mm Hg, in the presence of a catalytic system comprising an organometallic compound and activated carbon, characterized in that tetrabutoxytitanium / tetrabutoxytitanium / activated carbon is used as the organometallic compound 0.004: 1 to, 05: 1, respectively, the amount of catalyst system being from 0.2 to 10% by weight of the dialkyl esters of starting dicarboxylic acids.


    

Claims (1)

2. A method according to claim 1, characterized in that a catalytic system is used comprising tetrabutoxytitanium and activated carbon in a weight ratio of 0.008: 1 to 0.009: 1, respectively, the amount of catalytic system being 1, 5 to 2.5% by weight of the dialkyl esters of starting dicarboxylic acids. 3. Polyesters of glycols and dicarboxylic acids, characterized in that they are obtained by the process which is the subject of one of claims 1 and 2.