JP3345379B2 - Method for producing ester - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a method for producing an ester by an esterification reaction between a carboxylic acid and a polyoxyalkylene alcohol. More specifically, the present invention relates to a method for producing a plasticizer that does not cause a fogging phenomenon when used as a component of a resin composition.

[0002]

2. Description of the Related Art Esters obtained from carboxylic acids and polyoxyalkylene alcohols are known to be useful as plasticizers for lowering the glass transition point of resins, especially urethane resins, and imparting flexibility to the resins. It is widely used as a plasticizer for films and molded products. In the production of this ester, the carboxylic acid and the polyoxyalkylene alcohol are converted to benzene, toluene, sulfuric acid, paratoluenesulfonic acid, methanesulfonic acid, phosphoric acid, an acid catalyst such as boron trifluoride diethyl ether complex. The esterification reaction has been performed in a solvent such as xylene or without a solvent.

[0003]

However, in the esterification reaction using the above-mentioned conventional acid catalyst, a large amount of the acid catalyst is required for the esterification reaction to proceed smoothly due to low reactivity. Further, in the esterification reaction using an acid catalyst, a side reaction occurs in which the ether bond of the polyoxyalkylene alcohol is cleaved by the acid catalyst at the same time as the intended esterification reaction to form a low-molecular alkylene glycol, which is an esterification reaction. A large amount of lower diesters such as alkylene glycol dicarboxylic acid esters are produced as by-products. When a resin using a plasticizer containing these by-products is heated, the above-mentioned by-products evaporate from the resin surface, condensing on the surface of glass or the like, and cause a so-called fogging phenomenon that causes fogging. Are known. Due to the fogging phenomenon, for example, when a plasticizer containing the above-mentioned by-product is used for an interior resin of an automobile, there arises a problem that a windshield is fogged and visibility is significantly deteriorated. In the esterification reaction using the above acid catalyst, since the esterification reaction and the cleavage of the ether bond of the polyoxyalkylene alcohol proceed in parallel, only the esterification reaction is selectively performed only by examining the reaction conditions. It was difficult to prevent the formation of by-products.

[0004] Further, in the esterification reaction between a carboxylic acid and a polyoxyalkylene alcohol by an acid catalyst described in the above prior art, coloring during esterification is large,
There is a problem that the color tone of the resin used as a plasticizer is deteriorated.

[0005]

The inventor of the present invention has made intensive studies to solve the above-mentioned problems, and as a result, has arrived at the present invention. That is, the present invention provides an esterification reaction comprising using a titanium catalyst represented by the following general formula (2) in an esterification reaction between a carboxylic acid and a polyoxyalkylene alcohol represented by the following general formula (1). It is a manufacturing method. R— [O (AO) _m —H] _n (1) wherein R is an n-valent hydrocarbon group or hydrogen atom having 1 to 30 carbon atoms, A is an alkylene group having 2 to 4 carbon atoms, and m is 4 ~
An integer of 200, n represents an integer of 1 to 10] O = Ti (OCOQCOOM) ₂ (2) [wherein, M represents an alkali metal, Q represents a direct bond or an alkylene group having 1 to 10 carbon atoms]

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION The polyoxyalkylene alcohol in the present invention is represented by the following general formula (1). R- [O (AO) _m -H] _n (1) [wherein, R represents an n-valent hydrocarbon group or a hydrogen atom having 1 to 30 carbon atoms, A represents an alkylene group having 2 to 4 carbon atoms, and m represents 4 to
An integer of 200 and n represents an integer of 1 to 10] Examples of the hydrocarbon group R having 1 to 30 carbon atoms include an n-valent alcohol residue or a phenol residue. As the alcohol, a saturated or unsaturated monool (methyl alcohol, ethyl alcohol, n-, i-propyl alcohol, n-, i-, sec-, t-butyl alcohol, linear or branched nonyl alcohol, nonadecyl alcohol Diols (such as ethylene glycol, propylene glycol, and 1,4-butanediol); triols (such as glycerin and trimethylolpropane); tetraols (such as pentaerythritol); (Sorbitol, puffed rose, etc.). Examples of the phenols include monohydric phenols (phenol, cresol, naphthol, an alkyl group having 1 to 20 carbon atoms [methyl, linear or branched propyl, nonyl, nonadecyl,
Or one or two mono- or dialkylphenols having one or two tetracosyls); dihydric phenols (catechol, resorcin, hydroquinone, 1 carbon atom)
Mono- or dialkyldihydroxybenzenes having one or two alkyl groups [methyl, linear or branched propyl, nonyl, nonadecyl, tetracosyl, etc.]; trihydric phenols (pyrogallol, phloroglucin, 1 to 20 carbon atoms) Mono- or dialkyltrihydroxybenzene having one or two alkyl groups such as methyl, linear or branched propyl, nonyl, nonadecyl and tetracosyl).
Of R in the above formula of the polyoxyalkylene alcohol, preferably a hydrogen atom, a saturated or unsaturated monool residue having 8 to 18 carbon atoms, a mono- or 2-alkyl group having 1 or 20 alkyl groups, or A dialkylphenyl group, more preferably a hydrogen atom, having 8 to 1 carbon atoms.
6 saturated or unsaturated monool residues, 4 to 12 carbon atoms
Mono- or dialkylphenyl group having one or two alkyl groups, particularly preferably a hydrogen atom,
It is a saturated or unsaturated monool residue having 8 to 12 carbon atoms, or a monoalkylphenyl group having one alkyl group having 4 to 12 carbon atoms.

The alkylene oxide (hereinafter abbreviated as AO) in the general formula (1) includes ethylene oxide,
1. propylene oxide, 1.2-butylene oxide,
3-butylene oxide, isobutylene oxide, oxetane, methyloxetane, and tetrahydrofuran, among which ethylene oxide, propylene oxide, 1.2-butylene oxide and tetrahydrofuran are preferable, and ethylene oxide and propylene oxide are more preferable. . AO is one or two
Any combination of two or more species may be used. Examples of the addition form of AO include homopolymerization, random copolymerization and block copolymerization. From the viewpoint of compatibility between the plasticizer and the resin of the present invention,
Of these, homopolymerization or block copolymerization is preferable, and homopolymerization is more preferable. The number m of added moles of AO is usually an integer of 4 to 200, preferably 4 to 10
It is an integer of 0, more preferably an integer of 4 to 50.

As an example of the method for producing a polyoxyalkylene alcohol in the present invention, an alcohol catalyst or an alkali catalyst such as potassium hydroxide, sodium hydroxide or cesium hydroxide or an acid catalyst such as boron trifluoride diethyl ether complex can be used. After adding, usually 60-
It is synthesized by addition polymerization of AO at 180 ° C. under a pressure of 0 to 0.7 MPa. Examples of the addition form of AO include homopolymerization of one type of AO, random copolymerization in which two or more types of AO are mixed in advance and then polymerization, and block copolymerization in which two or more types of AO are sequentially polymerized in a block shape.

The carboxylic acids in the present invention include aromatic carboxylic acids and saturated or unsaturated aliphatic carboxylic acids. As aromatic carboxylic acids, those having 7 to 7 carbon atoms
15 mono and polycarboxylic acids having 8 to 18 carbon atoms. Examples of the aromatic monocarboxylic acid include benzoic acid and naphthalene carboxylic acid, and examples of the aromatic polycarboxylic acid include dicarboxylic acid (such as 2,6-naphthalenedicarboxylic acid, isophthalic acid, and terephthalic acid); and tricarboxylic acid (tricarboxylic acid). And a polyvalent carboxylic acid having four or more valences (eg, 1,2,4,5-tetracarboxylbenzene).
Examples of the saturated or unsaturated aliphatic carboxylic acid include monocarboxylic acids having 2 to 20 carbon atoms and polycarboxylic acids having 2 to 20 carbon atoms. Examples of the monocarboxylic acid include acetic acid, octylic acid, lauric acid, and oleic acid. Examples of the polycarboxylic acid include dicarboxylic acid (such as oxalic acid, adipic acid, sebacic acid, and maleic acid); and tricarboxylic acid (α, β, γ-tricarboxypropane, etc.).
Among these, preferred from the viewpoint of compatibility with the resin when used as a plasticizer are aromatic monocarboxylic acids having 7 to 15 carbon atoms, aromatic dicarboxylic acids having 8 to 18 carbon atoms, and those having 8 to 12 carbon atoms. It is a saturated or unsaturated aliphatic carboxylic acid, more preferably an aromatic monocarboxylic acid having 7 to 11 carbon atoms, an aromatic dicarboxylic acid having 8 to 16 carbon atoms, particularly preferably an aromatic carboxylic acid having 7 to 11 carbon atoms. Group monocarboxylic acids,
It is an aromatic dicarboxylic acid having 8 to 12 carbon atoms.

The titanium catalyst in the present invention is represented by the following general formula (2). O = Ti (OCOQCOOM) ₂ (2) [wherein, M represents an alkali metal, Q represents a direct bond or an alkylene group having 1 to 10 carbon atoms] As the alkali metal, lithium, sodium, potassium, rubidium, and cesium are used. Preferred among these are lithium, sodium, potassium,
More preferred are sodium and potassium. Q is a direct bond or an alkylene group having 1 to 10 carbon atoms,
Of these, a direct bond or a group having 1 to 4 carbon atoms is preferable.
And more preferably a direct bond or an alkylene group having 1 to 2 carbon atoms, particularly preferably a direct bond. Specific examples of the catalyst include alkali titanium oxalates such as sodium sodium oxalate, potassium potassium oxalate, lithium lithium oxalate and the like; corresponding malonates, succinates, glutarates, adipates and the like. No. Of these, preferred from the viewpoint of catalytic activity are alkali titanium oxalates,
It is an alkali titanium malonate, more preferably an alkali titanium oxalate, particularly preferably potassium titanium oxalate and sodium sodium oxalate.

The amount of the titanium catalyst represented by the general formula (2) is usually 0.001 to the carboxyl group of the carboxylic acid.
0001 to 10 mol%, preferably 0.000001 to 5 mol%, more preferably 0.000001 to 1 mol%, from the viewpoint of low coloring property of the produced ester.

In the esterification reaction of the present invention, the equivalent ratio of the carboxyl group of the carboxylic acid to the hydroxyl group of the polyoxyalkylene alcohol is usually from 1 / 0.5 to 1/2, preferably from the viewpoint of the smoothness of the esterification reaction. 1 / 0.5 ~
1/1, particularly preferably 1 / 0.8 to 1/1. The reaction temperature of the esterification reaction of the present invention varies depending on the composition of the carboxylic acid and the polyoxyalkylene alcohol and whether or not a solvent is used during the reaction, but is usually in the range of 120 to 230 ° C.

The esterification reaction of the present invention is usually carried out at normal pressure, and the reaction is carried out while removing the condensed water formed outside the system. If necessary, a solvent such as benzene, toluene, xylene, ethylbenzene or hexane is used. The condensed water can be azeotropically distilled off with the solvent. When a solvent is used, the amount of the solvent used is usually 5 to 200% based on the weight of the reaction system. Further, from the necessity due to the properties such as the sublimability and boiling point of the carboxylic acid or polyoxyalkylene alcohol as the raw material, a pressure (for example, 0.05 to 0.5 MPa) esterification method or a reduced pressure (for example, -0.1 to -0.01 MPa)
An esterification method can also be used.

In the esterification reaction of the present invention, if necessary, an antioxidant such as a hydroquinone (for example, hydroquinone, paramethoxyphenol, etc.) and a hindered phenol (for example, di-tert-butylhydroxytoluene, etc.), The reaction may be carried out by adding a reducing agent such as sodium phosphate or sodium borohydride for the purpose of preventing coloration and preventing thermal deterioration. The amount of the antioxidant and / or reducing agent used is usually 0.001 to 1%, preferably 0.001 to 1% based on the weight of the whole reaction system.
0.1%.

In the esterification reaction of the present invention, each of the carboxylic acid and the polyoxyalkylene alcohol can esterify not only a single compound but also a mixture of two or more compounds at an arbitrary ratio. The end point of the esterification reaction can usually be confirmed by measuring the amount of condensed water distilled off, measuring the acid value of the reaction system or quantifying the unreacted carboxylic acid by gas chromatography or the like,
The resulting ester may be a completely esterified product or a partially esterified product.

In the present invention, the monoalkylene glycol dicarboxylic acid ester and dialkylene glycol dicarboxylic acid ester which are low boiling point (100 to 280 ° C.) impurities causing fogging phenomenon contained in the ester are usually used in high performance liquid chromatography, gas chromatography and the like. The content is usually 3000 ppm or less, preferably 1500 ppm or less, and particularly preferably 500 ppm or less.

The esterified product obtained by the esterification reaction of the present invention can be used as it is as a plasticizer for the resin. If necessary, filtration, water washing, alkaline water washing, decolorization using activated carbon, etc. Alternatively, purification may be performed by an adsorption treatment using a hydrotalcite-based treating agent or activated clay.

The ester of the present invention is used as a plasticizer such as urethane resin, urethane acrylic resin, urethane epoxy resin, urethane polyester resin and urethane silicone resin. Resin compositions comprising these resins and plasticizers are used in molded articles for transport interiors, parts for power transmission, coating materials for information transmission materials, rollers, sealing materials, building sealants, films and the like. The amount of the plasticizer added to the resin varies depending on the application, but is usually 5
It is preferably from 150 to 150% by weight, more preferably from 5 to 100% by weight, particularly preferably from 5 to 80% by weight.

[0019]

The present invention will be described in detail with reference to the following Examples, but it should not be construed that the present invention is limited thereto.

Example 1 244 g (2 mol) of benzoic acid, 335 g (1 mol) of polyethylene glycol having a molecular weight of 335, and 0.51 g (0.0014 g) of potassium titanium oxalate were placed in a 1-L glass reaction vessel equipped with a Dean-Stark apparatus. Mol) and 70 g of xylene, and the temperature was raised to 200 ° C. while performing a submerged pass of nitrogen at a flow rate of 30 ml / min. 200 ° C
After the arrival, the esterification reaction was carried out at that temperature for 8 hours, and the condensed water generated during the reaction was removed out of the reaction system. After washing the obtained product with a 5% by weight aqueous solution of sodium carbonate,
Xylene was distilled off at 120 to 135 ° C. under a reduced pressure of −0.09 MPa to obtain 540 g of an ester. The obtained ester had a saponification value of 201 and an acid value of 0.3. From analysis by high performance liquid chromatography, the main component was polyethylene glycol dibenzoate, and the content of by-product ethylene glycol dibenzoate was 95 p.
pm, the content of diethylene glycol dibenzoate was 88 ppm.

Example 2 A block adduct 564 of ethylene oxide and propylene oxide obtained by adding 6 mol of ethylene oxide to 1 mol of polypropylene glycol having a molecular weight of 300 in place of the polyethylene glycol having a molecular weight of 335 of Example 1
The esterification reaction and the post-treatment were carried out under exactly the same conditions as in Example 1 except that g (1 mol) was used. The obtained ester was 769 g, its saponification value was 140 and acid value was 0.4.
Met. From analysis by high performance liquid chromatography, the main component was polyoxypropylene-polyoxyethylene glycol dibenzoate, and the content of by-product ethylene glycol dibenzoate was 98 ppm,
The content of diethylene glycol dibenzoate is 9
It was 0 ppm.

Example 3 In place of polyethylene glycol having a molecular weight of 335 of Example 1, 440 g (1 mol) of polyoxyethylene nonylphenyl ether obtained by adding 5 mol of ethylene oxide to 1 mol of nonylphenol was used to prepare benzoic acid 122
The esterification reaction and the post-treatment were carried out under exactly the same conditions as in Example 1 except that g (1 mol) was used. The amount of the obtained ester was 540 g, the saponification value was 94, and the acid value was 0.3. Analysis by high performance liquid chromatography revealed that the main component was polyoxyethylene nonylphenyl ether benzoate, the content of by-product ethylene glycol dibenzoate was 90 ppm, and the content of diethylene glycol dibenzoate was 86 ppm. .

Comparative Example 1 The esterification reaction and the post-treatment were carried out under exactly the same conditions as in Example 1 except that 4.1 g (0.02 mol) of paratoluenesulfonic acid was used in place of the potassium titanium oxalate of Example 1. Was done. The amount of the obtained ester was 539 g, the saponification value was 200, and the acid value was 0.4. From analysis by high performance liquid chromatography, the main component was polyethylene glycol dibenzoate, and the content of by-product ethylene glycol dibenzoate was 65400 p.
pm, the content of diethylene glycol dibenzoate was 55800 ppm.

For Examples 1 to 3 and Comparative Example 1, the number of colors was measured and the occurrence of fogging was evaluated, and the results are shown in Table 1. The number of colors is JISK0071-1993
(Gardner method). In addition, regarding the evaluation of the occurrence of the fogging phenomenon, the inner diameter was 50 mm and the length was 15 mm.
5.0 g of a sample was placed in a cylindrical glass container with a bottom of 0 mm, covered with a transparent glass plate having a thickness of 4 mm, then immersed in an oil bath at 100 ° C. to a position 50 mm from the bottom, and left standing and heated for 24 hours. . Thereafter, the transmittance of the transparent glass plate was measured, and it was determined that the higher the transmittance, the less occurrence of the fogging phenomenon. The substances adhered to the transparent glass plate of Comparative Example 1 were confirmed to be ethylene glycol dibenzoate and diethylene glycol dibenzoate by gas chromatography / mass spectrum.

[0025]

[Table 1]

[0026]

The ester obtained by the production method of the present invention for producing an ester from a carboxylic acid and a polyoxyalkylene alcohol does not contain a lower diester which is a low-boiling impurity. This is extremely useful without causing a fogging phenomenon and without deteriorating the color tone of the resin.

Claims (3)

(57) [Claims] 1. An ester production method comprising using a titanium catalyst represented by the following general formula (2) in an esterification reaction between a carboxylic acid and a polyoxyalkylene alcohol represented by the following general formula (1). Method. R— [O (AO) _m —H] _n (1) wherein R is an n-valent hydrocarbon group or hydrogen atom having 1 to 30 carbon atoms, A is an alkylene group having 2 to 4 carbon atoms, and m is 4 ~
An integer of 200, n represents an integer of 1 to 10] O = Ti (OCOQCOOM) ₂ (2) [wherein, M represents an alkali metal, Q represents a direct bond or an alkylene group having 1 to 10 carbon atoms] 2. The method for producing an ester according to claim 1, wherein the amount of the titanium catalyst used is 0.000001 to 10 mol% based on the carboxyl group of the carboxylic acid. 3. The carboxylic acid is an aromatic monocarboxylic acid having 7 to 15 carbon atoms, an aromatic polycarboxylic acid having 8 to 18 carbon atoms, or a saturated or unsaturated aliphatic monocarboxylic acid having 2 to 20 carbon atoms. The method for producing an ester according to claim 1, wherein the ester is a saturated or unsaturated aliphatic polycarboxylic acid having 2 to 20 carbon atoms.