JPS6310727B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a novel method for producing polyesters using crude 1,2-butanediol and monohydric alcohol.

Ester plasticizers such as dioctyl phthalate (DOP) and dioctyl adipate have been widely used to improve the processability and flexibility of synthetic resins. Among these, polyester plasticizers are preferred for applications that require durability such as heat aging resistance and oil resistance.

Polyesters used as polyester plasticizers generally include ethylene glycol, 1,3
-Propanediol, 1,3-butanediol,
A polyhydric alcohol such as 1,4-butanediol is condensed with a polyhydric carboxylic acid such as phthalic acid, adipic acid, trimellitic acid, etc. to form a monohydric alcohol or
Manufactured by terminal treatment with carboxylic acid.
The performance of the polyester as a plasticizer is correlated with its degree of polymerization (average molecular weight), and the lower the degree of polymerization, the better the plasticizing efficiency, cold resistance, processability, etc., but the lower the degree of polymerization, the better the plasticizing efficiency, cold resistance, processability, etc. Performance such as non-migration properties deteriorate, and on the other hand, those with a high degree of polymerization have poor compatibility with synthetic resins compared to monomeric plasticizers such as dioctyl phthalate, resulting in a decrease in plasticization efficiency and processability. At the same time, the biggest drawback is that the viscosity of polyester is high and workability is poor. That is, none of the conventional polyester plasticizers has low viscosity and excellent compatibility with synthetic resins.

In addition, conventional polyesters use the above-mentioned alcohols as polyhydric alcohols, but they are usually produced by the reaction of butadiene and acetic acid.
1,2-Butanediol, which is produced as a by-product during the production of butanediol, contains 1-acetoxy-2-hydroxybutane, 1-hydroxy-
Because it contains impurities such as acetoxy compounds such as 2-acetoxybutane and 1,2-diacetoxybutane, and because the amount produced is small, it has not been used as an alcohol for polyesters. Furthermore, in order to use 1,2-butanediol, which is a by-product during the production of 1,4-butanediol, it is necessary to first go through a purification process to remove impurities contained in it. , 2-butanediol is commonly used. However, since the amount of by-product 1,2-butanediol is small, it is economically disadvantageous to even perform purification treatment, and the 1,2-butanediol by-product is currently discarded or incinerated. It was hot.

The present inventors have obtained crude 1,2-butanediol containing impurities produced as by-products during the production of 1,4-butanediol.
As a result of intensive research into using butanediol directly in the production of polyester without purifying it and treating the ends of polybasic acids with monohydric alcohol, we found that
First, by condensing a basic acid or its anhydride with crude 1,2-butanediol, removing acetic acid produced by transesterification during condensation, and then condensing the condensate with a monohydric alcohol. It was discovered that a polyester of very good quality can be easily produced, and the obtained polyester can be used well as a plasticizer, has a low viscosity in spite of its high average molecular weight, and has good compatibility with synthetic resins. was found to be superior to other polyester plasticizers.

The object of the present invention is to produce crude 1,2-butanediol (hereinafter referred to as 1,2-BG) containing an acetylated product such as acetoxybutane, which is a derivative of 1,2-butanediol (hereinafter referred to as 1,2-BG).
An object of the present invention is to provide a method for producing a polyester which is terminal-treated with a monohydric alcohol without being affected by acetic acid produced by transesterification from 2-butanediol (hereinafter referred to as crude 1,2-BG).

Therefore, the gist of the present invention is to produce a polyester from a polybasic acid or its anhydride, a polyhydric alcohol, and a monohydric alcohol, using a crude 1,2-hydroxybutane or diacetoxybutane as the polyhydric alcohol. B.G.
The method of producing a polyester is characterized in that a polybasic acid and crude 1,2-BG are condensed in advance, acetic acid is removed from the condensed system, and a monohydric alcohol is then added for terminal treatment.

To explain the present invention in detail, the polybasic acid used in the polyester manufacturing method of the present invention is defined as having at least two carboxyl groups (including anhydride) in the molecule.
As long as it has this, it may be any type, regardless of whether it is aliphatic, aromatic, or alicyclic, and those used in the production of polyesters used in conventional polyester plasticizers are usually used. Specifically, phthalic anhydride, isophthalic acid, terephthalic acid, trimellitic anhydride, pyromellitic anhydride,
Examples include adipic acid, azelaic acid, sebacic acid, etc., and these may be used alone or in combination of two or more. In the present invention, in particular, phthalic anhydride,
Preferred are trimellitic anhydride and adipic acid.

The crude 1,2-BG used in the method of the present invention is normally produced as a by-product during the production of 1,4-butanediol through the reaction of butadiene and acetic acid.
BG contains various acetoxy compounds. When an example of crude 1,2-BG is measured by gas chromatographic analysis, its composition is, for example, 54% by weight of 1,2-BG, 1-acetoxy-2
-Hydroxybutane 23% by weight, 1-hydroxy-
It consists of 8% by weight of 2-acetoxybutane, 10% by weight of 1,2-diacetoxybutane, and 5% by weight of other 1,3-butanediol, 1,4-butanediol, etc., and the main impurities are 1,2-diacetoxybutane. -It turns out to be an acetoxylated product of BG.

The method of the present invention uses crude 1,
It is characterized by the fact that it can be used without any problems even if it is 2-BG, and it is also an advantageous point.

Furthermore, in addition to crude 1,2-BG, conventionally used alcohols can be used in combination with the polyhydric alcohol in the method of the present invention. in particular,
Polyhydric alcohols such as ethylene glycol, 1,3-propanediol, 1,3-butanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, neopentyl glycol, pentaerythritol, etc. A polyester having desired physical properties can also be produced by using them in combination as appropriate.

In the method of the present invention, a monohydric alcohol, which serves as a molecular weight regulator, is added during the production of polyester.
Examples of monohydric alcohols include, but are not limited to, methanol, ethanol, propanol, butanol, pentanol, hexanol, heptanol, n-octanol, 2-ethylhexanol, nonanol, decanol, undecanol, dodecanol, tridecanol, and the like. These can be used alone or in combination of two or more. Among these alcohols, alcohols having 4 to 13 carbon atoms, particularly 6 to 10 carbon atoms are preferred. When using polyester as a plasticizer,
Products with a small number of carbon atoms have good compatibility with synthetic resins, but are slightly less durable than those with a large number of carbon atoms.Conversely, products with a large number of carbon atoms are difficult to remove excess alcohol. tend to be difficult,
Moreover, the compatibility becomes poor. Therefore, it is best to use the ranges mentioned above.

The amount of crude 1,2-BG used when producing polyester by the method of the present invention is determined by converting the acetoxyhydroxybutane and diacetoxybutane contained in the crude 1,2-BG into the amount of 1,2-BG. It is desirable to use the polybasic acid in an amount of 0.1 to 1.3 times equivalent, preferably 0.3 to 1.1 times equivalent, per equivalent of polybasic acid. Of course, when crude 1,2-BG and other polyhydric alcohols are used together, the total amount is 0.1 to 1.3 times equivalent. The amount of monohydric alcohol to be used is not particularly limited since excess monohydric alcohol is discharged out of the system during condensation, but it is preferable to use 0.02 to 6 equivalents per equivalent of polybasic acid. . More specifically, for example, coarse 1,2-BG or coarse 1,2-
Mixture of BG with other dihydric alcohols20
The most preferred range is 49 to 49 molar ratios, 40 to 50 molar ratios of dibasic acids, and 40 to 2 molar ratios of monohydric alcohols.

To produce polyester by the method of the present invention, first, a polybasic acid and crude 1,2-BG are heated in the presence or absence of a catalyst, optionally in a nitrogen atmosphere, to produce a crude 1,2-BG. - Perform esterification by removing the acetic acid and water produced from the system while performing transesterification with acetoxyhydroxybutane, diacetoxybutane, etc. in BG. The heating temperature is not particularly limited, but it is desirable to carry out the reaction at least at the boiling point (azeotropic point) of the reaction mixture. After the reaction has progressed to a certain extent, the pressure in the system is reduced, and then deacetic acid and dehydration are performed while gradually increasing the degree of reduced pressure. At this time, in order to facilitate the release of acetic acid and increase the recovery rate, a solvent that forms an azeotropic composition with acetic acid or an acetic acid-water system,
For example, toluene, xylene, n-octane, ethylcyclohexane, butyl ethyl ether, etc. can be coexisting.

After deacetic acid is removed, a monohydric alcohol is added to the system and heated, and the unreacted portions of the polybasic acid are terminally treated while being dehydrated, and then excess alcohol is removed while gradually increasing the degree of vacuum. If removal of acetic acid is insufficient, esters of monohydric alcohol and acetic acid are produced, resulting in increased consumption of monohydric alcohol and the esters being included in the polyester. Further, an operation is required to remove the ester from the polyester.

As the catalyst, metal compounds such as diethyltin oxide, dibutyltin oxide, tin oxide, zinc oxide, tetraisopropyl titanate, tetrabutyl titanate, etc. are usually used.

According to the method of the present invention, 1,2-
BG, especially 1-acetoxy-2-hydroxybutane, 1-hydroxy-2-acetoxybutane,
Crude 1,2-BG, which is produced as a by-product during the production of 1,4-butanediol containing acetoxy compounds such as 1,2-diacetoxybutane, can be used directly in the production of polyester without being purified, and By removing acetic acid produced by transesterification and condensation reaction between basic acid and crude 1,2-BG,
It does not cause any hindrance to the production of polyester. The polyester thus obtained itself has a low viscosity and can be used as a novel polyester plasticizer with excellent compatibility with synthetic resins. The polyester obtained by the method of the present invention can be used as a plasticizer for thermoplastic resins such as vinyl chloride resin, vinylidene chloride resin, vinyl acetate resin, vinyl butyral resin, and methyl methacrylate resin, or as a solvent and diluent for paints. used as.

When the polyester produced by the method of the present invention is used as a plasticizer in vinyl chloride resin, it is added in an amount of 20 to 300 parts by weight, preferably 30 to 200 parts by weight, per 100 parts by weight of vinyl chloride resin, and tumbled. Mix or knead uniformly with a mixer, box mixer, ball mill, ribbon mixer, chain mixer, super mixer, crusher, mixing roll, Σ blade kneader, Banbury mixer, high-speed twin-screw continuous mixer, extruder type kneader, etc. It is used as a resin composition. The composition is used for applications such as films, sheets, containers, flooring materials, wall materials, and PVC steel plates.

The method of the present invention will be explained in detail below using Examples, but the present invention is not limited to the following Examples unless it departs from the gist thereof.

The obtained polyester was found to have ester bonds (-COO-) by infrared spectroscopy (IR).
The presence of hydroxyl groups (-
Confirm the disappearance of OH) and use a BM type viscometer to
The viscosity at °C was measured. The average molecular weight was calculated by hydrolyzing the obtained polyester and determining the constituent molar ratio of the raw materials of the polyester.

Example 146 g (1.0 mol) of adipic acid, crude 1,2-BG (composition: 1,
2-BG55% by weight, acetoxyhydroxybutane
35% by weight, diacetoxybutane 10% by weight) 102g
(0.95 mol), dibutyltin oxide as catalyst
0.25 g was added, and the temperature was gradually raised to 200°C under a nitrogen atmosphere to perform deacetic acid and dehydration. The degree of reduced pressure was gradually increased and finally reached 30 mmHg. It took 3 hours for this transesterification reaction and deacetic acid reaction.

As a result of analysis, the acetic acid aqueous solution recovered in this step had the following composition.

Amount recovered 41.2g Acetic acid 21.2g Recovery rate 91% Water 18.6g 68% Crude 1,2-BG 1.4g Next, 29g (0.22 mol) of 2-ethylhexanol was added to the reaction solution that had undergone acetic acid removal, and the mixture was heated at 200°C for 4 hours. A dehydration condensation reaction was performed. The degree of pressure reduction was started from atmospheric pressure, was increased to 30 mmHg, and was maintained at 30 mmHg to completely remove produced water.

The produced crude polyester was subjected to vacuum distillation by further increasing the degree of vacuum to 5 mmHg, resulting in an initial distillation of 5.7 mmHg.
g, 197 g of polyester was obtained. The entire process took 9 hours. The first distillation contained 3.3 g of 2-ethylhexyl acetate, which corresponds to 5% of the theoretical amount of acetic acid.

2 g of the obtained polyester was placed in a 300 ml flat bottom flask containing 2 g of potassium hydroxide, 30 ml of water, and 30 ml of ethanol, and heated under boiling conditions for 3 hours with a condenser attached. After cooling, 4 ml of concentrated hydrochloric acid was added to make an acidic solution. Adipic acid in aqueous solution, 1,2-
The proportions of BG, 2-ethylhexanol and acetic acid were analyzed by gas chromatography and were as follows.

Adipic acid 1.20g 8.2×10 ^-3 mol 9.1 molar ratio 1,2-BG 0.64g 7.1×10 ^-3 mol 7.9 molar ratio 2-ethylhexanol
0.24 g 1.8 x 10 ^-3 mol 2.0 molar ratio Acetic acid 0.006 g 1.0 x 10 ^-4 mol 0.1 molar ratio This shows that it is a polyester with an average degree of polymerization of about 8 and an average molecular weight of 2100.

The viscosity was 1800 cp and the acid value was 0.72 mgKOH/g.

Comparative Example In a flask similar to that used in Example 1, 146 g (1.0 mol) of adipic acid and 102 g (0.95 mol) of crude 1,2-BG were added.
mol), 2-ethylhexanol 29g (0.22 mol)
and 0.25g of dibutyltin oxide, 200
The condensation reaction was carried out while gradually raising the temperature to ℃. 3
After an hour, distillation of water-acetic acid stopped under reduced pressure of 30 mmHg.

The analysis results of the distillate were as follows.

Amount recovered 26g Acetic acid 10g Recovery rate 43% Water 13.9% 51% Crude 1,2-BG 0.8g 2-ethylhexanol 1.3g This indicates that the added 2-ethylhexanol was consumed as acetic acid ester and the reaction stopped. There is.

Therefore, an additional 29 g of 2-ethylhexanol
(0.22 mol) was added and dehydration condensation was continued, and no water-acetic acid was distilled out after 5 hours. The acid value of the reaction solution was 0.68 mgKOH/g.

Next, the reaction solution was vacuum distilled by reducing the pressure to 5 mmHg, yielding 40.9 g of initial distillate and 195 g of polyester. The entire process took 11 hours.

During the initial distillation, 30.8 g of 2-ethylhexyl acetate was recovered, and the total amount with the distillate fraction was 32.1 g, accounting for 48% of the theoretical amount of acetic acid.
This indicates that ethylhexanol was wasted.

Polyester has an average molecular weight of 2200, a viscosity of 1850 cp,
The acid value was 0.83 mgKOH/g.

As mentioned above, the time required for the reaction varies greatly depending on whether or not acetic acid is removed in advance during the condensation reaction, and there are also differences in the amount of monohydric alcohol used. turns out to be extremely advantageous.

Claims (1)

[Claims] 1. In producing polyester from polybasic acid or its anhydride, polyhydric alcohol and monohydric alcohol, using crude 1,2-butanediol containing acetoxyhydroxybutane or diacetoxybutane as the polyhydric alcohol, A method for producing polyester, which comprises preliminarily condensing a polybasic acid and crude 1,2-butanediol, removing acetic acid from the condensed system, and then adding a monohydric alcohol for terminal treatment.