JP3547002B2 - Method for producing esters - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a method for producing esters (that is, including complex esters and polyesters), and more particularly to a method for producing the esters having an extremely narrow molecular weight distribution by a transesterification reaction.
[0002]
[Prior art]
Conventionally, it has been considered difficult to produce polymer esters from a reactant having one terminal OH group. That is, in an esterification reaction with a dibasic acid, such a reaction product terminates chain elongation, and also in a transesterification reaction having an ester bond in such a reaction product, Such reactants terminate the chain extension and, furthermore, no suitable catalyst has been found which allows such a reactant chain extension.
[0003]
In addition, when a polymer ester is produced by a conventional method, it is produced as a mixture of a plurality of compounds having different numbers of n, and has a molecular weight distribution in which the ratio decreases exponentially as the number increases sequentially from n = 1. Only such a high molecular ester could be produced. The reason for this is that when an ester is formed, the reaction does not always start from the end as shown in the formula, and the ester bond in the structural formula undergoes transesterification mainly due to attack by the terminal alcohol ROH. Therefore, the product has a composition where n = 1 is large. Japanese Patent Application Laid-Open No. 8-157418 discloses a retro reaction, that is, HOXO (COACOOXO)._nIn the reaction of OH, n = 1 should not be produced when an acid reacts at both ends with an ester bond, but it is described that n = 1 is most frequently produced in distribution measurement by liquid chromatography HPLC. I have. On the other hand, RO (COACOOXO)_nThe production of complex esters represented as COACOOR has already been reported in many patents and its reaction process has been proposed. It has also been proposed that, while producing esters using an improved catalyst, a composite ester having excellent performance can be produced by circulating diesters as a by-product by effectively utilizing their properties. (Japanese Patent Application 2000-147554).
[0004]
[Problems to be solved by the invention]
The present invention makes it possible to extend the chain of a reactant having such an ester bond and having an OH group at the terminal by a transesterification reaction, and further to produce an ester having a very narrow molecular weight distribution at a desired degree of polymerization. It is an object of the invention to provide a process for the production of esters which makes it possible.
[0005]
[Means for Solving the Problems]
The subject of the present invention is a reactive ester composition of dibasic acid (HOOCACOOH), diol (HOXOH) and terminal alcohol (ROH) (RO (COACOOXO)_nH) (n ≧ 1) in which a reactant is reacted under reduced pressure of 100 mmHg or less in the presence of a titanium catalyst to produce esters. As the reactive ester composition, a reactive ester composition (ROCOACOOOXOH) having a molar ratio of dibasic acid (HOOCACOOH), diol (HOXOH) and terminal alcohol (ROH) of 1: 1: 1 is preferable. This reactant has the general formula:
R'O (COACOOXO)_nCOACOOR '
(In the formula, R's may be the same or different, and each represents an alkyl group which may be the same as R.)
[0006]
Here, the dibasic acid (HOOCACOOH) may be adipic acid or phthalic acid or a mixture thereof, R of the terminal alcohol (ROH) is preferably an alkyl group, and more preferably 4 to 10 carbon atoms. Diol (HOXOH) is ethylene glycol, 1,2-propanediol, 1,3-butanediol, 1,4-butanediol, 1,6-hexanediol, 2-ethyl-1,3-hexanediol, molecular weight Is at least one selected from the group consisting of polyethylene glycol having a molecular weight of 1,000 or less, preferably 500 or less, more preferably 300 or less, and polypropylene glycol having a molecular weight of 1000 or less, preferably 500 or less, more preferably 300 or less. Good.
[0007]
The titanium catalyst is alkoxytitanium, or a mixture of alkoxytitanium, a water-soluble polyol and water, or a reaction product of the mixture, with the latter being particularly preferred.
Here, alkoxytitanium is tetrabutoxytitanium and tetramers thereof, tetraisopropyloxytitanium, tetraethoxytitanium, tetrafunctional titanium such as tetraoctyloxytitanium and the like, alcohol solutions such as titanium trichloride and titanium tetrachloride, Including compounds called orthotitanates and the like, tetrabutoxytitanium, tetraisopropyloxytitanium or tetraoctyloxytitanium is preferred, and tetrabutoxytitanium is more preferred. The water-soluble polyol is not particularly limited as long as it is a water-soluble compound having two or more hydroxyl groups, but ethylene glycol, propanediol, diethylene glycol or glycerin is preferable. The number of moles of the water-soluble polyol relative to 1 mole of titanium in the alkoxytitanium is 1 to 50 moles, preferably 5 to 20 moles, more preferably 8 to 15 moles, and similarly, the mole number of water is 1 to 60 moles. , Preferably 4 to 40 mol, more preferably 10 to 20 mol. These may be mixed simply at room temperature or by heating or dissolved in a solvent, and the mixing order is not limited.
[0008]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, the diol is described as a general formula as HOXOH, the monofunctional terminal alcohol is described as ROH, the phthalic acid is described as HOCOPCOOH, and the adipic acid is described as HOCOACOOH. Further, for the sake of simplicity, an ester bond (-COO-) may be omitted in the description.
First, a reaction composition of a dibasic acid diol-terminated alcohol will be described. When an equimolar amount of a terminal alcohol is added to a dibasic acid and a diol to perform an esterification reaction to convert the acid into an ester, the alcohol equivalent of the diol and the terminal alcohol becomes three with respect to two equivalents of the dibasic acid. Naturally, various products are formed, and an ester alcohol and an ester are formed.
ROH + HOCOACOOH + HOXOH → RAXOH + RAR + HOXAXOH + RAXAR + RAXAXOH + ROH
[0009]
The actual contents include not only the composition but also RAR and HOXAXOH, which are in equimolar relation. When the transesterification proceeds next, these two become RAXAXOH + ROH, and R (AX)₂It is expected to show the same behavior as OH. Also, the composition of RAXAR and HOXAXOH in a one-to-one relationship becomes RAXOH + RAXAXOH in a transesterification reaction, and 2R (AX)_1.5It is assumed that it behaves the same as OH. That is, the product is R (AX)_nIt can be indicated by the composition of OH. This n varies depending on the conditions of the reaction.
Considering these facts, the one-to-one one-to-one dehydration esterification reaction composition has a theoretical composition of RAXOH, but since a by-product is formed, the product is R (AX)._nCan be handled as OH. Such a composition can also be produced by reacting a diester with an equimolar amount of a diol.
[0010]
RAR + HOXOH → RAXOH + ROH + RAR + HOXOH + HOXAOH
Next, transesterification is performed using this composition.
RAR + HOXOH → RAXOH + ROH (1)
RAR + RAXAXOH → RAXAXR + ROH (2)
RAXAR + RAXOH → RAXOH + RAXAR or RAXAXAR + ROH (3)
RAXAXAR + RAXOH → RAXAXOH + RAXAR, RAXOH + RAXAXAR, or RAXAXAXAR + ROH (4)
RAXAR + nRAXOH → RAX (AX)_nAR + nROH (5)
[0011]
The sequential reactions shown in (1) to (5) proceed, and in the reaction with the diester RAR, a complex ester having a composition with a small polymerization degree n due to excessive use of the diester, and further from the complex ester, depending on the reaction amount of RAXOH, Esters having a high degree of polymerization represented by the formula (5) are produced in accordance with the elimination of ROH in the transesterification reaction. It is conceivable that the transesterification reaction occurs not only at the terminal but also inside the polyester structure, but in that case, the terminal alcohol is generated and the transesterification reaction proceeds again, and as a result, the dealcoholization reaction proceeds at the terminal, The product is a product having a high degree of polymerization. As can be seen from the results of the experiment, in the reactions (1) and (3), the reaction (3) proceeds more easily than the reaction (1). As a result, in the reaction between RAR and RAXOH, the reaction after (3), which is a product, proceeds simultaneously or sequentially, so that RAR cannot be quantitatively reacted, and remains unreacted until the end and reacted. From the ratio of RAR, the product (AX)_nWill be calculated.
[0012]
Composite ester is RO (COACOOXO)_nIt is described as COACOOR and its composition is produced as a mixture of a plurality of compounds having different numbers of n. In particular, in the conventional production method, the proportion becomes smaller as the number increases sequentially from n = 1. Has a molecular weight distribution. Unless a special production method was used, a complex ester showing a normal distribution could not be produced. The reason for this is that when an ester is formed, the reaction does not always start from the end as shown in the formula, and the ester bond in the structural formula undergoes transesterification mainly due to attack by the terminal alcohol ROH. Therefore, the product has a composition where n = 1 is large.
[0013]
RAR + HOXAXOH + RAR → RAXAXAR (6)
RAR + HOXAXOH → RAXAXOH + ROH (7)
RAXAXOH + ROH → RAR + HOXAXOH, RAXOH + RAXOH, or RAXAR + HOXOH (8)
RAXOH + RAR → RAXAR + ROH (9)
RAR + HOXOH + RAR → RAXAR (10)
[0014]
The reason is that ROH is formed first in the reaction (7), and when the ROH reacts, the various reactions described in (8) proceed. In (9), n = 1 can be increased, and HOXOH formed in (8) can be obtained. Next, generation (10) of n = 1 is performed. It is assumed that ROH is always formed in the transesterification reaction, and n = 2 should be formed when the reaction is carried out in the solution. Even in the reaction (6), the product is mostly n = 1 in the reactions (8) to (10). Is done.
When 2 mol of phthalic anhydride is reacted with 1 mol of diol, diol ester carboxylic acid can be almost quantitatively produced by an anhydride reaction. When ROH is added and esterified,
ROH + HOCOXPXPCOOH + HOR → RPXPR (11)
RPXPR + ROH → RPR + RPXOH (12)
RPXOH + RPXPR → ROH + RPXPXPR (13)
RPXPXPR + ROH → RPR + RPXPOXOH (14)
RPPXOHH 11 → n = 3, n = 4 (15)
[0015]
In the formula (11), the bis compound n = 1 is quantitatively generated. However, when the reaction is actually performed, the reactions of the formulas (12) to (15) proceed one after another in a mixture up to n = 7. Further, the process proceeds to n = 7. Since ROH can generally be reached only by using an excess in order to quantitatively advance the esterification reaction, such a reaction proceeds not only with titanium, which is a catalyst for the transesterification reaction, but also with other catalysts. The resulting complex ester results in a sharp increase in viscosity, which is thought to be due to the structure of PXXPP. If the viscosity is high, the plasticizing performance becomes poor when used as a plasticizer, and n = 1 and n = 2 of only the phthalic acid unit. The corresponding complex ester has not been made. Both of these descriptions have described the effects of ROH. However, since the influence of ROH is large in the dehydration esterification reaction of a complex ester or polyester, a method of sequentially adding ROH in small amounts for the purpose of controlling the molecular weight distribution, and further, a diol component However, it is also known that 2-ethyl-1,3-hexanediol is relatively hardly affected as a diol component that is hardly attacked by an ester group, and as a result, the distribution can be controlled. Therefore, by performing the reaction under reduced pressure in order to eliminate the influence of ROH, the retro-reaction is reduced. In the reaction corresponding to the formula (6), when phthalic acid diol diester is used and ROH is octanol, dioctyl is used. It is described that phthalate by-product (formula (14)) is prevented.
[0016]
When phthalic anhydride is used as the dibasic acid in the present invention, the reaction is started with 1 mole of the phthalic anhydride and 1 mole of the diol, and the ester alcohol obtained by adding one mole of the monofunctional alcohol and esterifying is used. For the first time, high-molecular-weight (PX)_nCan be produced. In the transesterification reaction, it is impossible to perform a completely equimolar reaction, so that it is preferable to use as many diesters as possible to carry out the reaction quantitatively. The transesterification reaction will be described with RPXOH in place of (1) RAXOH and phthalic acid in place of adipic acid.
In this reaction, the product is obtained by removing the ROH generated by heating the mixed solution (Patent No. 2517245). However, since retro-reaction occurs simultaneously, when phthalic acid is used, (PX)_nN = 3 or more are by-produced and the viscosity is increased.
[0017]
In the present invention, the transesterification reaction is carried out under reduced pressure, preferably 100 mmHg or less, more preferably 30 mmHg or less, more preferably 0.2 to 25 mmHg, particularly preferably 0.5 to 2 mmHg. Further, it is preferable that the temperature is preferably 160 to 250 ° C., preferably 180 to 220 ° C., which is high near the boiling point of RAR, and the transesterification is carried out little by little.
When the number of moles of the diester RAR used in this reaction is 2 or less, the degree of polymerization of the product becomes 2 or more. The amount is large, resulting in poor efficiency. If the amount is less than 1.5 mol, the viscosity becomes high and the features of the present method are lost. The composition of the product obtained is obtained by subtracting the yield from the theoretical calculation amount, and assuming that the RAR mole number of the g number does not participate in the reaction, the reaction mole number and the reaction ratio are calculated, and the reciprocal is (PX)_nIs calculated as n. (PX)₂Does not necessarily mean PXXPP, and it is considered that there is no influence on the reaction of ROH in this reaction, and the unit of the product has a structure of PXAXP, so that a low-viscosity product is obtained. Conceivable.
[0018]
Adipic acid, unlike the anhydride reaction of phthalic acid, cannot perform a selective reaction.However, if the addition of a terminal alcohol is performed with priority on the reaction between a diol and an acid, by-products of diester RAR are reduced, but in particular, complex If a small bis compound of the ester n is not selectively produced, it is used without any problem in calculating the degree of polymerization by using it as it is. R (AX)_nOH, R (PX)_nOH was calculated by removing the reaction product as a volatile component under reduced pressure, removing toluene used as an azeotropic rib, unreacted terminal alcohol and 1-octanol, and calculating the difference between the calculated amount and the weight of the product. The reaction mole number can be calculated by dividing the mole number by the molecular weight of octanol and subtracting the mole number from the calculated usage amount, and the ratio can be calculated. The reciprocal of the ratio is (AX)_nIs calculated as the degree of polymerization of n. The value varies somewhat depending on the manner of the reaction, but the value is approximately from 1.1 to 1.3. The value can be used by calculating the average molecular weight by removing ROH, but the mixture can be used without removing ROH. Can be used as n = 1.
[0019]
In the case of adipic esters, a composition having a wide molecular weight distribution may be obtained by partially performing a retro-reaction, but the target is obtained by performing a transesterification reaction under reduced pressure to obtain a higher molecular weight. Polyesters of a degree of polymerization can be produced, in particular, as low acid number, low alcohol terminated products. Regarding the molecular weight distribution, the transesterification reaction proceeds at the terminal, but the transesterification reaction also proceeds inside the polyester. At that time, the second from the end, the formula (4), the retro reaction also occurs. Therefore, it is not considered that a normal distribution can be completely obtained. However, since the retrofitting reaction by ROH is controlled, it is expected that the molecular weight distribution will probably be close to the normal distribution.
[0020]
In Example 6 to be described later, a polyesterification reaction was carried out for a molecular weight of 3500 from a complex ester having a degree of polymerization of 4 obtained by a direct sequential addition dehydration esterification reaction, but a by-product of a low molecular weight diester RAR was observed. And it is not necessary to remove the low-molecular-weight portion by high-temperature distillation after polymerization. On the other hand, in the reaction with the diester (Example 5), even with the use of twice the molar amount of R (AX) OH ester alcohol, almost 20% of the RAR still remains unreacted and, therefore, 20% of the intended composition. It was calculated that the molecular weight increased soon.
It is well known that, among composite esters, the formation of different composite esters improves water resistance. For this purpose, R (AX)_nOH and R (PX)_nOH can be produced individually or in a mixture, the addition amount can be determined according to the desired composition, and a different component can be added before or after, and the transesterification reaction can be carried out to achieve the purpose. Taken together, the features of this reaction are that the molecular weight and composition can be easily controlled according to the purpose, and the acid value alcohol value is substantially zero, and the molecular weight distribution of the alcohol-terminated polyester is regulated. It is a feature of this patent that it has the potential to provide such products.
[0021]
【Example】
In this example, in order to express the composition, A: adipic acid, P: phthalic acid, R: terminal alcohol (2-ethylhexanol), R ': terminal alcohol (1-octanol), X_DP: Dipropylene glycol used as a diol component, X_13B: Each symbol of 1,3-butanediol used as a diol component was used, and the degree of polymerization was described as a composition in parentheses (). These diols and terminal alcohols are not limited to those described in the examples, but various diols and terminal alcohols (C₄~ C₁₀The same theory applies to alcohols).
The ethylene glycol water-activated titanium catalyst used in the following examples was prepared as follows. 0.65 g (36 mmol) of water was added to 1.49 g (24 mmol) of ethylene glycol, mixed, and 0.41 g (1.2 mmol) of tetrabutoxytitanium was added little by little to mix. It becomes a mixture. 10 g of octanol was added to this gel-like polyol polytitanic acid catalyst, and the mixture was stirred and dispersed to obtain a polyol water-activated titanium catalyst.
[0022]
Example 1
To a mixture of 1 mol of adipic acid (146 g), 1 mol of ethylene glycol (62 g) and 1 mol of 1-octanol (130 g) was added 1 mmol of an ethylene glycol-activated titanium catalyst made from 0.34 g of tetrabutoxytitanium. Was added as an azeotropic solvent, and a dehydration esterification reaction was performed for 2.5 hours. As a result, 36 g of water was removed, and the acid value became 0.1. 30 ml of this product was put into a 500 ml reaction vessel and stirring was started. The pressure was reduced to 1 mmHg at 200 ° C., and after distilling off octanol, the remaining amount of the product was added little by little to the reaction vessel. Deoctanol transesterification was performed, and finally the temperature was adjusted to 200 ° C. and 0.5 mmHg. This reaction was continued for 2.5 hours to obtain 135 g of a distillate. This is close to the calculated amount of octanol, including toluene. Toluene and a small amount of water were added to the reaction product to carry out a treatment for the purpose of inactivating the catalyst. As a result, 172.5 g of a hardly soluble high-viscosity polyester which could not be treated with toluene water was obtained. This product crystallizes upon cooling to form a cloudy wax, and it is considered that the polyester-terminated end is a polyester having an octyl ester structure. The number of moles of the polyester having a terminal octanol is calculated as (172.5-172) /130=0.0038, the polymerization degree is the reciprocal of 263, and the molecular weight is 45366.
[0023]
Example 2 (Ester alcohol and diester reaction / molar ratio RPXOH: R'AR '= 1: 2)
A mixture of 0.33 mol (49.6 g) of phthalic anhydride and 0.33 mol (44.7 g) of dipropylene glycol was heated and stirred to carry out an anhydride reaction, and 0.33 mol of 2-ethylhexanol (43. In 3 g), 1.5 mmol of an ethylene glycol water-activated titanium catalyst was suspended and added to the reaction solution to carry out a dehydration esterification reaction. 1.5 hours after the addition, the acid value became 0.1, and the reaction was completed for 30 minutes. The reaction solution was divided into 2 minutes, and 66.4 g of this reaction product (0.166 mol as the reaction product RPXOH for each 1 mol) was added with 0.34 mol (125.5 g) of dioctyl adipate (R′AR ′) and It was added at a pressure of 5-1 mmHg under reduced pressure to a reaction solution containing 0.8 mmol of a titanium catalyst.
Octanol containing toluene was distilled off corresponding to the addition, and 29.7 g was recovered. When the addition transesterification reaction was completed and the temperature was lowered to 100 ° C., 5 ml of water was added and stirred. After 2 hours, toluene was added and the mixture was subjected to dilution activated clay filtration, and the filtrate was distilled to remove the solvent. At ~ 250 ° C / 0.5 mmHg, 73.6 g of a product was obtained as a residual liquid except for volatile components (corresponding to R'AR 'and the like).
The difference of 32.1 g from the theoretical value of 105.7 g was calculated to be 0.087 mol of dioctyl adipate (mw = 370), the ratio of the reacted mole number 0.08 was 0.477, and the reciprocal 2.05 was the polymerization ratio. Become. As a result, the product is R (PX)_2.05AR 'molecular weight is 911.2. The viscosity at 20 ° C. was 868 centipoise.
[0024]
Example 3 (Reaction molar ratio RPXOH: R'AR '= 1: 2.5)
A small amount of octanol was added to 160.2 g of dioctyl adipate obtained by reacting 65.7 g (0.167 mol) of the RPXOH ester mixture obtained in the previous step of Example 2 and the mixture was stirred with an active titanium catalyst at 200 ° C. for 1 hour to reduce the acid value to 0. 0.06, octanol was removed under reduced pressure, and the mixture was added with stirring at 5 to 0.5 mmHg. After a further 30 minutes of the transesterification reaction, post-treatment distillation at 190 to 250 ° C./0.5 mmHg was carried out in the same manner as before, and dioctyl adipate was removed as a pre-fraction to obtain a product as a residual liquid. The weight was 78.5 g, the number of moles reacted was 0.0935, the ratio was 0.559, the reciprocal n was 1.79, and the viscosity at 20 ° C. was 664 centipoise.
[0025]
Example 4 (RAXOH: R'AR '= 1: 2.75)
After heating and stirring 0.33 mol (49.0 g) of phthalic anhydride and 0.33 mol (44.2 g) of dipropylene glycol, 43.3 g of 1.2 mmol of an ethylene glycol water-activated titanium catalyst was suspended. (0.333 mol) of 2-ethylhexanol was added to carry out a dehydration esterification reaction. After 2.5 hours, the acid value was 0.08, and the reaction was completed after another 20 minutes.
A mixture of 200 g of recovered dioctyl adipate and 76 g of new dioctyl adipate was evacuated to sufficiently remove the volatile matter under heating, and then the dehydration esterification reaction product was added thereto over 1.5 hours while stirring at 190 ° C./0.5 mmHg to form a mixture. The reaction was terminated by removing 42 g of the octanol. Water was added at 100 ° C. to inactivate the catalyst to remove the catalyst. The filtrate was concentrated, and the filtrate was concentrated and distilled under reduced pressure at 190 to 250 ° C./0.5 mmHg to remove 197 g of dioctyl adipate as a volatile matter. 157.9 g were obtained. Using the difference from the theoretical amount of 209.5 g as the diester, the number of moles of the reaction was calculated and the degree of polymerization 1.736 was obtained from the reciprocal of 0.576. From now on, the composition of the product is R (PX_{D P})_1.74The AR 'molecular weight 829 is calculated. The viscosity at 20 ° C is 464 centipoise and RPXA (XP)_0.74R's guessed, (PX)₂It is presumed that the viscosity was lowered due to the absence of. When the reaction molar ratio is changed to 2, 2.5, 2.75 and the product is observed, the degree of polymerization decreases to 2.05, 1.79, 1.74, but the viscosity decreases correspondingly. When the degree of polymerization exceeds 2, the viscosity rises sharply. When the viscosity is increased, the plasticization efficiency is correspondingly deteriorated when used as a plasticizer for polyvinyl chloride. Therefore, in order to obtain excellent plasticity, the reaction molar ratio is 2.5 to 2.75.
It is well known that the greater the number of phthalic acid units, the higher the water resistance and weather resistance.
[0026]
Example 5
To a mixture of 0.7 mol (102.2 g) of adipic acid, 0.7 mol (63 g) of 1,3-butanediol and 0.7 mol (91 g) of 1-octanol was added 2 mmol of an ethylene glycol water-activated titanium catalyst. In addition, after purging with nitrogen, a dehydration esterification reaction was carried out in the presence of a small amount of toluene under heating. After 2 hours and 15 minutes, the acid value was 0.10, and after 30 minutes, the esterification reaction was completed. It was concentrated under reduced pressure to remove toluene 1-octanol to obtain 214.2 g.
16.8 g less than the calculated amount, divided by 130 as octanol, the analytical use amount was corrected to 1.8 g, the reaction molar amount was 0.585 mol, and the ratio was 0.837. Degree of polymerization 1.196 Composition R (AX_13B)_{1 . 196}0.278 mol of dioctyl adipate having an OH molecular weight of 369.3 was maintained at 180 ° C./0.5 mmHg while heating and stirring at 180 ° C./0.5 mmHg, and 0.58 mol of the ester alcohol was added. Transesterification was performed. The theoretical composition is R (AX_13B)_2.08AR ', 0.278 mol, 218.6 g, octanol 74 g was almost quantitative when combined with the amount of the recovery destination. The post-treatment was carried out in the same manner as before to remove volatile components by distillation at 190 to 250 ° C./0.5 mmHg under reduced pressure to obtain 195.6 g of a residual product. The shortage of 23 g was divided by the molecular weight of the diester, and the molar ratio of 0.062 was 0.215. The ratio was 0.776. From now on, the composition is R (AX_13B)_2.68The AR 'molecular weight was 905.8. The viscosity at 20 ° C. was 224 centipoise.
[0027]
Example 6
Ethylene glycol water-activated titanium catalyst 2 was prepared by adding 0.4 mol (58.4 g) of adipic acid, 0.4 mol (36 g) of 1,3-butanediol and 0.4 mol (52 g) of 1-octanol to a small amount of toluene. The reaction was subjected to dehydration esterification by adding mmol. After 2.5 hours at 200 ° C., the acid value was 0.08. The toluene was removed under reduced pressure, and 130 g of the reaction solution was used for the next reaction. R (AX) was prepared by starting dehydration esterification by mixing 4 mol equivalents of adipic acid and 3 mol equivalents of 1,3-butanediol, which were separately prepared, and sequentially adding 2 mol equivalents of 1-octanol to dehydrate esterification._13B)_4.57AR ′ molecular weight 1264, viscosity 588 centipoise at 20 ° C., 0.035 mol (44.2 g), 0.8 mmol of tetrabutoxytitanium was added, and the above ester alcohol 130 g was stirred at 180 ° C./0.5 mmHg for 1 hour. Over half, the transesterification reaction was performed little by little, and 50 g of the produced octanol was recovered. The catalyst was inactivated according to a standard method, and the clay filtration filtrate was concentrated and distilled under reduced pressure to remove volatile components, thereby obtaining 122.0 g of a product as a residual liquid. Even at 250 ° C./0.5 mmHg, the volatiles did not show a distillate fraction showing the boiling point, and it was considered that almost no diester had reacted or disappeared. Since 0.4 / 0.035 = 11.42 times of RAXOH was reacted, the degree of polymerization was 4.57 + 11.42 = 15.98, and the composition of the product was R (AX_13B)₁₆The calculated AR 'molecular weight is 3570. The viscosity at 20 ° C. was 1952 centipoise.
[0028]
Example 7
To a mixture of 0.3 mol (43.8 g) of adipic acid and 0.15 mol (20.1 g) of dipropylene glycol was added 2.5 mmol of activated titanium catalyst together with 0.45 mol (58.5 g) of 2-ethylhexanol. To perform a dehydration esterification reaction. The product is a mixture of RAXOH and R'AR 'at 0.15 mole each. R (AX) manufactured separately for each purpose_{D P})_1.2OH and R (PX_{D P}) OH was prepared separately. To 0.5 mol of adipic acid, 0.5 mol of dipropylene glycol and 0.5 mol of 2-ethylhexanol, add 2 mmol of activated titanium catalyst and dehydrate esterify at 200-210 ° C. using a small amount of toluene. The reaction was carried out to reduce the acid value, and then 176.2 g of a product was obtained by removing volatile octanol at 25 mmHg and 100 ° C. or less under reduced pressure. The calculated degree of polymerization was 1.20 and the molecular weight was 422.8, of which 0.3 mol was used. On the other hand, R (PX_{D P}) OH was made in the following manner. 0.1 mole (13.4 g) of dipropylene glycol in 0.1 mole (27.8 g) of dibutyl phthalate and 0.1 mole (13 g) of 2-ethylhexanol and 0.8 mmol (0.3 g) of tetraethyl Butoxytitanium was added, and the mixture was heated and stirred at 180 ° C. at normal pressure and finally at 200 mmHg to remove butanol produced. Thus, approximately 14 g of butanol was obtained, and the reaction was terminated and used for the addition reaction.
[0029]
First, the solution of RAXOH + R'AR 'is depressurized, and the temperature is increased while stirring to remove octanol produced. The temperature is lowered to 180 ° C, the depressurized pressure is set to 15 mmHg, and then R (AX_{D P})_1.200.3 mol of OH (126.8 g) followed by R (AX_{D P}) 0.1 mol (39 g) of an OH reaction solution was sequentially added, and transesterification was carried out, except for about 70 g of octanol produced, and after 2 hours, the pressure was increased to 0.5 mmHg, and the temperature was maintained for 30 minutes to terminate the reaction. According to an ordinary method, the solvent was distilled off under reduced pressure except for the post-treatment solvent to obtain 195.5 g of a product as a residue. Theoretical value of product R (AX_{D P})_3.4(AX_{D P})_0.66For 206.3 g of AR ', n = 1.24 and therefore the composition of the product is R (AX_{D P})_4.22(PX_{D P})_0.83AR 'molecular weight was 1619, and viscosity at 820 was 820 centipoise.
[0030]
【The invention's effect】
From the above examples, the esters R (AX)_nIt can be seen that a transesterification reaction occurs in the ester bond portion of the polyester in the reaction between AR (n is an integer including 0) and RAXOH, and that the polymer is formed by a dealcoholization reaction.
In the reaction between the RAXOH ester bond and RAXOH, a sequential reaction proceeds as shown in the following formula to increase the molecular weight, and the polyester is formed according to the amount of ROH removed.
RAXOH + nRAXOH → R (AX)_nAXOH + nROH
Here, removal of the terminal alcohol becomes a problem. If the diol component is removed at the same time as the alcohol is removed, the diol component becomes alcohol at both ends and the molecular weight decreases. Therefore, the diol component may be excessive, but the polymerization proceeds in accordance with the reaction amount of the diol, and one side of the diol component increases. Polyesters having terminal alcohols mainly containing terminal alcohols are formed. In the present invention, by solving such a problem of removing the terminal alcohol, it is possible to produce an ester having a very narrow molecular weight distribution at a desired degree of polymerization.
[0031]
The process for producing esters according to the present invention is characterized in that esters having an ester bond and having an OH group at the terminal can be extended by a transesterification reaction, and further, esters having an extremely narrow molecular weight distribution at a desired degree of polymerization. Enables the manufacture of
Esters thus prepared having a very narrow molecular weight distribution at the desired degree of polymerization exhibit the following characteristics:
1) Since it has an appropriate molecular weight and a narrow molecular weight distribution, it has little or no low molecular weight components, and thus is volatile-resistant.
2) The composite ester of 500 cp or less has a good plasticization efficiency of 45 to 52 when the DOP is 50. A composite ester having a plasticization efficiency of 500 to 1,000 cp or less has a plasticizing efficiency of 50 to 54 and is somewhat poor, but has an intermediate property between the composite ester and the polyester.
3) Although ordinary polyesters having a large molecular weight have poor plasticity, the esters of the present invention have a low migration property in a vinyl chloride polymer corresponding to the molecular weight and become a plasticizer excellent in solvent resistance.
4) When phthalic acid is contained in the composite ester, the viscosity increases and the plasticity deteriorates, but the water resistance improves. 0.3 units or more are required to maintain the minimum water resistance. In Examples 2 to 4, esters of 500 cp or less could be produced using phthalic acid, which could not be produced until now.
5) When only adipic acid is used as the dibasic acid, it varies depending on the diol component, but generally has poor water resistance. However, it is a plasticizer excellent in low-temperature characteristics as its feature.

Claims (3)

A reactant comprising a reactive ester composition (RO (COACOOXO) _n H) (n ≧ 1) of a dibasic acid (HOOCACOOH), a diol (HOXOH) and a terminal alcohol (ROH) is treated in the presence of a titanium catalyst at a pressure of 100 mmHg or less. A method for producing esters by reacting under reduced pressure. The reactant is further represented by the general formula:
R'O (COACOOXO) _n COACOOR '
(Wherein R ′ may be the same or different, and represents an alkyl group which may be the same as R). The titanium catalyst is a mixture of alkoxytitanium, a water-soluble polyol and water, or a gel comprising a reaction product of the mixture, and the mole number of the water-soluble polyol and water is 5 to 20 moles per mole of the titanium. 3. The method according to claim 1, wherein the amount is from 4 to 40 mol.