JPH11116533A - Production of polyacetylated compound of polyhydric alcohol and production of crosslinked polyester resin - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for simply producing the polyacetylated compound of a polyhydric alcohol, without requiring complicated production processes and capable of omitting a purifying process and a method for producing a crosslinked polyester resin capable of progressing a uniform reaction. SOLUTION: The production of the polyacetylated compound of a polyhydric alcohol is to feed a polyhydric alcohol and an equal molar amount of acetic anhydride based on the hydroxyl groups in the polyhydric alcohol, heat the mixture with stirring, keep a heating temperature until the amount of acetic acid distilled off from the reaction solution reaches >=90% of the theoretical amount, as acetic acid vapor having 115 deg.C boiling point is generated with the progression of the reaction, further distil off acetic acid by reducing the pressure at a stage in which the temperature of acetic acid vapor becomes lower and the generation of acetic acid vapor is not recognized, maintain the reduced pressure until no foaming is observed on the liquid surface, stop reducing of the pressure, discharge the melt in a reaction vessel and obtain the polyacetylated compound of the polyhydric alcohol. A crosslinked polyester resin is produced by polymerizing a dicarboxylic acid with a diol using the plyacetylated compound as a crosslinking component.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for easily protecting hydroxyl groups of a polyhydric alcohol in order to control the reactivity of the polyhydric alcohol used as a crosslinking component in the production of polyester resins and alkyd resins. And a method for producing a crosslinked polyester resin using a polyacetylated product of a polyhydric alcohol.

[0002]

2. Description of the Related Art Polyethylene terephthalate (PE)
T) and polyester resins represented by polybutylene terephthalate (PBT) are industrially important materials.
These resin materials include fibers (tetron, gold-silver deposited yarn, etc.), films (photographs, magnetic tapes, electrical insulation,
It is used for various purposes such as packaging, agricultural use, molding (bottles, containers, etc.), glass fiber reinforced exterior (housing, electronic / electric parts related applications, etc.), and in these applications, mechanical strength Therefore, those having a linear structure and a relatively high molecular weight are preferably used.

On the other hand, in the field of paints, which are special applications, the properties of paints, for example, the state of the coating film (gloss, smoothness, etc.) are more important than the mechanical strengths of the above-mentioned applications. Molecular weight distribution is more important than molecular weight. In such a case, as a technique for adjusting the molecular weight distribution of the polyester resin, a trifunctional or more functional component is used for a part of the alcohol component and the carboxylic acid component of the monomer constituting the polyester, and a partial crosslinking is performed in the resin. Method of introducing a structure and introduction of a post-crosslinkable unsaturated bond (double bond or triple bond) or other reactive group (hydroxyl group, amino group, isocyanate group, nitrile group, etc.) into the structure of the monomer component. There is a method.

However, in the above-described method of introducing another reactive group to introduce a crosslinked structure, it is necessary to devise a method so that the introduced reactive group does not react at the time of polyester synthesis. Never be. Therefore, a technique of using a monomer having a trifunctional or higher functional group at the time of polyester synthesis is widely used.

[0005] Examples of trifunctional or higher functional monomers used for introducing a crosslinked structure into a polyester resin include the following. First, as the trivalent or higher carboxylic acid component, trimellitic acid, 1,2,4-cyclohexanetricarboxylic acid, 1,2,4-naphthalenetricarboxylic acid,
Examples thereof include 2,5,7-naphthalenetricarboxylic acid, pyridinetricarboxylic acid, pyridine-2,3,4,6-tetracarboxylic acid, 1,2,7,8-tetracarboxylic acid, and butanetetracarboxylic acid. Acid anhydrides or lower alkyl esters thereof can be used.

[0006] The trihydric or higher polyhydric alcohol component includes sorbitol, 1,2,3,6-hexane tetrol, 1,4-sorbitan, pentaerythritol, dipentaerythritol, tripentaerythritol,
1,2,4-butanetriol, 1,2,5-pentanetriol, glycerol, diglycerol, 2-methylpropanetriol, 2-methyl-1,2,4-butanetriol, trimethylolethane, trimethylolpropane, etc. Can be considered.

[0007]

However, since most of the monomers of the carboxylic acid component having a valency of 3 or more are high-melting compounds, it is necessary to use these monomers to uniformly carry out the reaction of forming a crosslinked polyester resin. Is difficult. Therefore, when a monomer of a carboxylic acid component having a valency of 3 or more is used as a cross-linking component, it is preliminarily esterified to lower the melting point, thereby enabling a uniform reaction at the time of polymerization.

On the other hand, in the case of trihydric or higher polyhydric alcohol components, few of them are liquid at room temperature and usually have a very high melting point, so that it is known that self-condensation occurs at a temperature near the melting point. In addition, since this kind of polyhydric alcohol has a high melting point, it is difficult to stir uniformly in the process of forming a crosslinked structure by reaction with a dicarboxylic acid component,
The reaction is likely to be uneven. Therefore, if the polyhydric alcohol component is used as it is, the resin properties tend to be unstable.

Further, in the esterification reaction using this kind of polyhydric alcohol, it takes time until the first hydroxyl group reacts with the carboxylic acid component to form an ester bond, but once the ester bond is formed. Once formed, the subsequent reaction is very fast, and a number of cross-linked structures are quickly formed and rapidly increase in molecular weight. For this reason, the melt viscosity or the solution viscosity sharply rises, uniform stirring is difficult to perform, and there is also a problem that it is difficult to react the raw materials stably and uniformly.

Among the trivalent or higher crosslinking components, in the case of carboxylic acid-based crosslinking agents, their esterified products are generally used in order to lower the melting point and improve the reactivity. At present, almost no attempt has been made to control reactivity, that is, to moderately lower the reactivity or lower the melting point of the alcohol-based crosslinking agent to achieve a homogeneous reaction.

As a method of controlling the reactivity of the alcoholic hydroxyl group to lower the melting point, a method of protecting the hydroxyl group can be exemplified. In general, a method for protecting the hydroxyl group of an alcohol in advance has been conventionally performed for a monohydric or dihydric alcohol. For example, as a method for protecting the hydroxyl group of a monohydric alcohol, generally, ether protection, ester protection, silyl alcohol, Many methods are used, such as tell protection, carbonate protection, nitration protection, and the like. Further, as a method for protecting the hydroxyl group of the dihydric alcohol, a protection method using a cyclic protecting group such as cycloacetal protection, cycloketal protection, or cycloorthoester protection is known.

On the other hand, methods for protecting trihydric or higher alcoholic hydroxyl groups are hardly known except for the following two methods. This can be seen in Theodora W. Greene's P
rotective Gropes in Organic Synthesis '' A Wieley-In
As described on page 10 of the terscience Publication.

A first specific example of a method for protecting the hydroxyl group of a trihydric or higher polyhydric alcohol is a method for synthesizing pentaerythritol tetraacetate. The reaction process of this synthesis method is as follows. Condensation reaction between formaldehyde and acetaldehyde → pentaerythritol → nitration reaction → pentaerythritol tetranitrate (PETN) → nitro-acetyl exchange reaction in concentrated sulfuric acid → pentaerythritol tetraacetate (Worfromctal. J. Am. Chem. Soc., 78 However, this method is not a simple method because it requires the use of PETN, which is an explosive substance, and requires purification in each step.

As a second specific example of the method for protecting the hydroxyl group of a polyhydric alcohol having a valency of 3 or more, a method of reacting acetic anhydride with pentaerythritol in a large amount of pyridine (this is also a method used for measuring the hydroxyl value). Is). However, this method not only requires the use of a large amount of highly dangerous pyridine, but also has a problem that the step of separating and purifying the product is time-consuming and economically poor.

The present invention has been made in view of the above circumstances, and provides a method for easily producing an acetylated trihydric or higher polyhydric alcohol useful for controlling the reactivity of a crosslinked polyester resin, and a reaction using the same. It is an object of the present invention to provide a method for producing a crosslinked polyester resin capable of controlling the properties.

[0016]

Means for Solving the Problems In order to achieve the above object, the present inventors have diligently studied an improvement in a method for protecting a hydroxyl group of a trihydric or higher polyhydric alcohol through a complicated process exemplified in the prior art. As a result, they have found a simple method for acetylating polyhydric alcohols that does not require a purification step, and have accomplished the present invention. That is, the method for producing a polyacetylated polyhydric alcohol according to the present invention is characterized in that a trihydric or higher polyhydric alcohol and acetic anhydride are reacted under heating without using a solvent other than acetic anhydride. . If necessary, acetic acid produced as a by-product with the progress of the reaction may be removed.

In the method for producing a crosslinked polyester resin according to the present invention, a polyacetylated product of a trihydric or higher polyhydric alcohol is used as a component for constructing a crosslinked structure when polycondensing a diol component and a dicarboxylic acid component. It is characterized by using. According to such a method for producing a crosslinked polyester resin, it is possible to lower the melting point of the high-melting polyhydric alcohol and to uniformly perform the polycondensation reaction of the crosslinked polyester while suppressing the self-condensation of the polyhydric alcohol. Become.

[0018]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, preferred embodiments of the present invention will be described in detail. In the method for producing a polyacetylated polyhydric alcohol according to a preferred embodiment of the present invention,
A trihydric and / or tetrahydric alcohol and an equimolar amount of acetic anhydride with a hydroxyl group of a polyhydric alcohol are heated under substantially no solvent other than acetic anhydride, that is, using only acetic anhydride as a solvent. To react. According to such a method, the advantages that the reaction end point can be easily confirmed, a large amount of solvent is not required, and a purification step is not required are obtained. Further, the present invention is also applicable to polyhydric alcohols having five or more valences.

The method for producing a polyacetylated polyhydric alcohol according to a preferred embodiment of the present invention comprises the following four steps. Step 1: In a reactor equipped with a stirrer and a distillation unit, a predetermined amount of polyol and acetic anhydride in an equimolar amount with respect to the amount of hydroxyl groups of the polyhydric alcohol are charged and heated while stirring. Both reactions proceed even at 100 ° C. or lower, but heating to 115 ° C. or higher, more preferably 130 to 160 ° C., generates acetic acid vapor at 115 ° C.
The temperature of 115 ° C. is the boiling point of by-produced acetic acid under normal pressure. By using acetic anhydride in an equimolar amount with respect to the hydroxyl group amount of the polyhydric alcohol, by collecting acetic acid produced as a by-product, the advantage that the degree of progress of the reaction can be easily confirmed is obtained. Is not limited to an equimolar amount, and the molar ratio of the hydroxyl group of the polyhydric alcohol to acetic anhydride may be 1: 0.25 to 1.00. If the acetic anhydride is not equimolar, a part of the hydroxyl groups of the polyhydric alcohol will remain, but the effect of controlling the crosslinking reaction rate during the synthesis of the polymer can be sufficiently obtained.

Step 2: The heating temperature is maintained until the amount of acetic acid distilled off from the reaction solution becomes 90% or more of the theoretical amount.
When acetic acid is not removed from the reaction system by reacting at a low temperature of 115 ° C. or less, there is no particular problem in the production of a polymer described later, but if acetic acid is removed simultaneously with the reaction, there is an advantage that separation and purification are performed simultaneously. . Step 3: When the temperature of the by-produced acetic acid vapor decreases and generation of acetic acid vapor is no longer recognized, the pressure is reduced to further distill off the by-produced acetic acid. The pressure reduction is continued until no foaming is seen on the liquid surface. The degree of reduced pressure is not limited, but is preferably 1 to 100 mmHg, and particularly preferably 1 to 100 mmHg.
-30 mmHg is preferred. Step 4: Stop the depressurization, discharge the melt in the reactor, and cool to obtain a polyacetylated polyhydric alcohol.

As the trihydric or higher polyhydric alcohol usable in the present invention, triols having a trimethylol type skeleton and tetraols having a neopentyl type skeleton or a tetramethylol skeleton are used for controlling the physical properties of a polyester resin or an alkyd resin. It is preferable because the degree of crosslinking can be easily adjusted.

These include the following substances. Triol having a trimethylol type skeleton,
And other triols that can be used in the present invention include trimethylolethane, trimethylolpropane, 2-methyl-propanetriol, 2-methyl-
Examples thereof include 1,2,4-butanetriol, 1,2,4-butanetriol and 1,2,5-pentanetriol. It is also possible to use these ethylene oxide equimolar adducts or polyethylene oxide adducts, and propylene oxide adducts or polypropylene oxide adducts.

Examples of the tetraol having a neopentyl type skeleton or the tetraol having a tetramethylol skeleton include pentaerythritol and 1,2,3,6-hexanetetraol. Further, these ethylene oxide equimolar addition products or polyethylene oxide addition products, and propylene oxide addition products or polypropylene oxide addition products can also be used. Examples of readily available polyethylene oxide adducts of pentaerythritol include pentaerythritol ethoxylate sold by Aldrich and polypropylene oxide adducts of Aldrich (Aldrich product code: 41,615-0, 41,873-0,
41, 874-9, 42, 502-8, etc.).

Other usable polyhydric alcohols include glycerin, sorbitol, 1,4-sorbitan,
Glycerol, diglycerol, dipentaerythritol, tripentaerythritol, natural polysaccharides and derivatives thereof can be mentioned. In addition, an ethylene oxide equimolar adduct thereof, a polyethylene oxide adduct thereof, a propylene oxide adduct thereof, or a polypropylene oxide adduct thereof can also be used.

In the method for producing an acetylated product of a polyhydric alcohol according to the present invention, a catalyst can be used in order to further increase the reaction rate and synthesize more easily. The catalyst used in this case may be any substance having a basic property that improves the reactivity of acetic anhydride, and in particular, tertiary amines and acetates are preferable because they effectively promote the reaction by the addition of a small amount. is there. Tertiary amines include aromatic benzyldimethylamine, pyridine, picoline,
Lutidine and the like include, as aliphatic amines, triethylamine, 1,8-diazabicyclo [5.4.0] undec-7-ene, 1,4-diazabicyclo [2.2.2] octane, 1,5-diazabicyclo [4.8.0] Nona
5-ene and the like can be used. As the acetates, sodium acetate, calcium acetate, nickel acetate and the like can be used.

Next, the method for producing a crosslinked polyester resin according to the present invention uses a polyacetylated product of a trihydric or higher polyhydric alcohol produced as described above as a crosslinking agent, and dicarboxylic acid and diol are used. It is characterized in that a polyester resin partially having a crosslinked structure is obtained by polymerization.

By using a low-melting-point cross-linking agent in which the hydroxyl group of the polyhydric alcohol of the high-melting point cross-linking component is acetyl-protected, uniform stirring can be performed from the beginning of the polycondensation reaction, and the cross-linked polyester resin having stable resin properties can be obtained. Can be easily manufactured.

In the method for producing a crosslinked polyester resin of the present invention, a particularly preferred polyacetylated product of a trihydric or higher polyhydric alcohol has a main skeleton represented by the following chemical formulas (1) to (3). .

Chemical formula (1): C (—CH ₂ —X—O—
C (＝ O) —CH ₃ ) _{4 wherein} X is absent or ethylene oxide: —O—CH ₂ —CH ₂ —, polyethylene oxide: — {O—CH ₂ —CH ₂ } _n —, Propylene oxide: —O—CH ₂ —CH (CH ₃ ) —, and polypropylene oxide: — {O—CH ₂ —CH (CH ₃ )} _n —. n means an integer of 2 or more.

Chemical formula (2): However, in the formula, both X and Y are ethylene oxide:-
O—CH ₂ —CH ₂ —, polyethylene oxide: — ｛O—
CH ₂ —CH ₂ ｝ _n— , propylene oxide: —O—CH ₂
-CH (CH ₃₎ -, and polypropylene oxide:
— {O—CH ₂ —CH (CH ₃ )} _n —, but not identical to each other. m and m ′ are each an integer of 1 to 3, and m + m ′ = 4.

Chemical formula (3): RC (-CH ₂ -X-
O—C (＝ O) —CH ₃ ) ₃ wherein R represents hydrogen or an organic group having 8 or less carbon atoms, and X represents none or ethylene oxide: —O—C
H ₂ —CH ₂ —, polyethylene oxide: — ｛O—CH ₂
—CH ₂ ｝ _n— , propylene oxide: —O—CH ₂ —C
H (CH ₃₎ -, and polypropylene oxide: -
_{{O-CH 2 -CH (CH} 3)} n - means any.

The acetylated product of the polyhydric alcohol represented by the chemical formulas (1) to (3) is preferably such that all the hydroxyl groups of the polyhydric alcohol are acetylated. It is permissible to use a product in which only a part is acetylated. When the ratio of acetylated hydroxyl groups to all hydroxyl groups is at least 25 mol%, more preferably at least 50 mol%, unreacted acetyl groups are introduced after non-acetylated hydroxyl groups are introduced into the main chain resin. Since the moieties form a crosslinked structure by transesterification, homogenization of the polycondensation reaction which is the object of the present invention,
The lowering of the temperature of the polyhydric alcohol is sufficiently achieved.

The compounds represented by the chemical formulas (1) to (3)
When one or more acetylated polyhydric alcohols are used as a cross-linking component of the polyester resin, the melting point of the high-melting polyhydric alcohol during the production of the polyester resin can be further lowered, and the polycondensation reaction can be carried out in a uniform state from the beginning of the polycondensation reaction. , And a resin having more stable properties can be produced.

The acetylated products of the polyhydric alcohols represented by the chemical formulas (1) to (3) are not limited to those obtained by the above-mentioned method for producing polyacetylated polyhydric alcohols.
A commercially available material can be used as it is. For example, an acetylated product of pentaerythritol is available as a reagent as pentaerythritol tetraacetate.

The diol component and dicarboxylic acid component that can be used in the present invention are not particularly limited as long as they are applicable to the melt polycondensation reaction. Specific examples of the diol include diethanolamine, ethylene glycol, diethylene glycol, propylene glycol, isoprene glycol, octanediol, 2,2-diethyl-1,3-propanediol, spiro glycol, neopentyl glycol, and 1,3-butanediol. , 1,4-butanediol, 2-butyl-2-ethyl-1,3-propanediol, 1,6-hexanediol, hexylene glycol, 1,5-pentanediol, 3-methyl-1,5-
Pentanediol, hydrobenzoin, bis (β-hydroxyethyl) terephthalate, bis (hydroxybutyl) terephthalate, polyoxyethylenated bisphenol A, polyoxypropylene-modified bisphenol A, polyoxyethylenated biphenol, polyoxypropylene-modified biphenol, etc. Can be exemplified.

Specific examples of dicarboxylic acids include fumaric acid, maleic acid, succinic acid, itaconic acid, mesaconic acid, citraconic acid, glutaconic acid, phthalic acid, isophthalic acid, terephthalic acid, 1,4-cyclohexanedicarboxylic acid, , 3-cyclohexanedicarboxylic acid, cyclohexenedicarboxylic acid, adipic acid, sebacic acid, dodecanedioic acid, eicosantioic acid, azelaic acid, brassic acid, naphthalenedicarboxylic acid, biphenyl-4,4'-
Dicarboxylic acid, 2,3-piperazinedicarboxylic acid, iminodicarboxylic acid, imidazole-4,5-dicarboxylic acid, piperidinedicarboxylic acid, pyrazoledicarboxylic acid, N-methylpyrazoledicarboxylic acid, N-phenylpyrazoledicarboxylic acid, pyridinedicarboxylic acid, Carbazole-3,6-dicarboxylic acid, 9-methylcarbazole-3,6-dicarboxylic acid, carbazole-3,6-dibutyric acid, carbazole-3,6-γ, γ′-diketobutyric acid and acid anhydrides thereof and their anhydrides Examples thereof include lower alkyl esters.

The catalyst used to promote the polycondensation reaction that can be used in the production of the crosslinked polyester resin of the present invention may be any catalyst that can be used in the production of the polyester resin. However, examples thereof include dibutyltin oxide, titanium tetrapropoxide, and organic germanium. However,
Antimony is not preferred from the viewpoint of toxicity.

The conditions of the polycondensation reaction may be the same as those of a general method for producing a polyester resin, and may be in an inert atmosphere (for example, a nitrogen atmosphere) or under reduced pressure, 1 mmHg to normal pressure (atmospheric pressure), 150 to 290 ° C. The reaction may be carried out for from 48 hours to 48 hours. In the case of the present invention, in particular, in an inert atmosphere, at 180 to 270 ° C. for 1 to 10 hours, further 1 mm
It is preferable to carry out the reaction at 220 to 270 ° C. for 1 to 8 hours under a reduced pressure of about Hg because it has an advantage that a uniform and transparent crosslinked polyester resin can be obtained.

In the method for producing a crosslinked polyester resin according to the present invention, in the polycondensation reaction process during the production of the polyester resin, after the diol monomer constituting the main chain of the polyester is consumed in the latter half of the reaction, the polycondensation component The exchange reaction of the acetic acid ester portion occurs in the acetylated polyhydric alcohol, and introduction of a crosslinked structure is started. As described above, since the crosslinked structure is formed after the main chain (linear resin portion) is formed, the molecular weight of the linear resin portion can be accurately controlled by the mixing ratio of dicarboxylic acid and diol, and the acetylated crosslinked portion can be formed. The physical properties of the entire resin can be easily controlled by adjusting the amounts of the components.

When a polyhydric alcohol which is liquid at room temperature or has a low melting point of 100 ° C. or less is used as a crosslinking agent, once the reaction starts, the reactivity increases more than the diol component, and it becomes difficult to control the resin properties. Although there was a phenomenon, according to the method for producing a crosslinked polyester resin of the present invention, geo-
Since the exchange reaction of the acetic acid ester portion is started at the stage when the condensation reaction of the toluene component is almost completed, there is a great advantage in that the control of the resin physical properties becomes easy. That is, the control of the molecular weight between the cross-linking points is difficult by the conventionally known synthesis method, but is excellent in that it can be easily carried out by the production method of the present invention.

High-melting-point polyhydric alcohols such as pentaerythritol self-condensate under heating at a high temperature of about 260 ° C. to form dipentaerythritol or tripentaerythritol, to form a desired crosslinked structure or to obtain a desired crosslink density. Although the regulation is inhibited, such a problem can be solved by protecting the hydroxyl groups with acetyl according to the method for producing a crosslinked polyester resin of the present invention.

The crosslinked polyester resin (including an alkyd resin) produced according to the present invention is preferable for use in special paints, for example, powder paints, binder resins for toners used in electrostatic recording systems, and the like. is there.

[0043]

EXAMPLES The method for producing a polyacetylated product of a polyhydric alcohol and the method for producing a crosslinked polyester resin according to the present invention will be described in detail below with reference to examples.

Example 1 Synthesis of Pentaerythritol Tetraacetate Acetic anhydride: 1.00 mol (102.8 g) was placed in a 200 mL three-necked round bottom flask equipped with a Liebig condenser and a mechanical stirrer. Pentaerythritol: 0.25 mol (34.0 g) was charged and heated to 150 ° C. with a mantle heater. After ripening, as the temperature inside the reactor increased, the solution became a uniform solution, and acetic acid vapor began to be generated. The reaction is continued as it is and the theoretical amount of 9
A fraction of 0.6% (54.4 g) was obtained.

Next, the pressure in the flask was reduced to about 25 mmHg by an aspirator, and the pressure was continued until foaming on the solution surface was eliminated. After decompression, release the contents to 200
The mixture was poured into a mL glass container, sealed, and allowed to stand at room temperature overnight. After standing, the contents solidified.
The melting point was measured using a melting point measuring apparatus manufactured by p Co., Ltd .: MP-41 type (glass capillary type). The measurement results were 83.5-
It was 84.0 ° C, which was consistent with the literature value of the melting point of pentaerythritol tetraacetate: 83 to 84 ° C, and it was confirmed that the product was highly pure. The yield was quantitative.

Example 2 Synthesis of Trimethylolpropane Triacetate Trimethylolpropane: 0.50 mol (65.57 mol)
g) and acetic anhydride: 1.50 mol (154.2 g), and trimethylolpropane triacetate was synthesized in the same manner as in Example 1, except that 0.01 g of sodium acetate hydrate was added as a catalyst. . After cooling, it turned into a hard honey-like liquid. When the infrared absorption was measured, it was confirmed that the absorption in the 3200 to 3600 cm ^-1 region specific to alcoholic hydroxyl groups had disappeared. No further analysis was performed.

[Example 3] Synthesis of tetraacetyl ester of pentaerythritol polyoxyethylene adduct pentaerythritol polyoxyethylene adduct “HE-400 manufactured by Sanyo Chemical Co., Ltd.” (hydroxyl value: 404 mg KO)
H / g; Formula weight 555.548): 0.25 mol (13
8.88 g) and acetic anhydride: 1.0 mol (102.8 g)
Was charged into a reactor, and 0.10 mL of pyridine was used as a catalyst.
The reaction was carried out in the same manner as in Example 1 except that was added, to obtain a viscous liquid. After completion of the reaction, disappearance of the alcoholic hydroxyl group was confirmed by infrared absorption analysis.

Comparative Example 1 Synthesis of Pentaerythritol Tetraacetate by Conventional Method Pyridine: 500 mL was placed in a 1-liter three-necked round bottom separable glassco equipped with a mechanical stirrer, a 200 mL dropping funnel, and a reflux condenser with balls. Put on an ice bath,
Acetic anhydride: 1.00 mol (102.8 g) from the dropping funnel.
Was added dropwise over 1 hour to prepare an acetylating agent. Then, pentaerythritol: 0.25 mol (34.00
g) was slowly added into the reactor, and reacted while stirring for 6 hours. The ice bath was replaced with a water bath, and the reaction was carried out at 60 ° C. with stirring for further 6 hours. After cooling, the reaction solution was poured into 10 liters of ice water, filtration and washing were repeated to separate pyridine and by-produced acetic acid from the solid. The solid was air-dried and then dried under vacuum overnight to obtain 54 g of crude pentaerythritol tetraacetate. Melting point is 8
The melting point range was as wide as 0.0 to 86.0 ° C., and the purity was low. This low-purity product was recrystallized three times using benzene to obtain pentaerythritol tetraacetate having the same melting point width as in Example 1. The isolation yield was 48.0%.

Comparative Example 2 Synthesis of Pentaerythritol Tetraacetate by Conventional Method 800 g of paraformaldehyde (a cyclic trimer of formaldehyde) (corresponding to 26.7 mol in terms of formaldehyde) was replaced with 210 g of acetaldehyde (4.77).
Mol) was added to a 20 L enamel container containing 5.5 L of water with stirring. Then, 180 g of powdered lime
(3.22 mol) was added in portions and the vessel was heated to 50 ° C. This state was maintained for 3 hours or more, and when the solution turned slightly yellow by the following reaction, suction filtration was performed to separate a solid product. 8CH ₂ O + 2CH ₃ CHO + Ca (OH) ₂ → 2C (C
The solid product of H ₂ OH) ₄ + (HCO ₂ ) ₂ Ca was repeatedly washed with diluted hydrochloric acid until the mother liquor became acidic. Then, the activated carbon /
Nolite mixture (manufactured by Aldrich, trade name: "No
write R0 0.8 "), and after decolorizing, recrystallized with hot water to obtain pentaerythritol crystals. The mother liquor was concentrated to obtain crystals up to the third crystal as a crude product. The yield was 415 g in total. The crude product was recrystallized from an aqueous solution obtained by adding 10 mL of hydrochloric acid to an equal amount of water, to obtain 360 g of purified pentaerythritol. The overall yield was 55%.

50 g of pentaerythritol obtained by the above method was added to 250 g of concentrated nitric acid cooled to ice temperature (1 g of urea was added to remove nitrous acid) with stirring, and the reaction was carried out as it was. The temperature was maintained until stopped. Next, 250 g of concentrated sulfuric acid was added to separate pentaerythritol tetranitrate (PENT), and then repeatedly washed with water in a large amount of water to remove nitric acid and sulfuric acid. Then, this crude product was mixed with an acetone / water mixed solution (volume ratio 2 /
Recrystallized in 8), isolation yield 68. PENT was obtained at 1%.

Using this PENT, a nitro-acetyl exchange reaction was performed according to the method of Worfrom et al. To obtain pentaerythritol tetraacetate in a crude yield of 95.1%.
The melting point of the crude product was 82.5-85.0 ° C. By performing recrystallization once with benzene, a product having the same melting point width as in Example 1 was obtained with a recrystallization yield of 67.0%. The overall yield was 22.5%. In addition, pentaerythritol was not synthesized, and a nitration and nitro-acetyl exchange reaction were separately performed using the same commercially available reagent as in Example 1. The total yield was as low as 43.8%.

[Evaluation] Example 1, Comparative Example 1 and Comparative Example 2 show different methods for acetyl protecting the hydroxyl group of pentaerythritol. In Comparative Example 1, a large amount of highly dangerous pyridine had to be used, and in order to obtain an acetylated product of pentaerythritol having the same purity, the purification step by recrystallization had to be repeated several times. In Comparative Example 2, when the method described in the literature is used, the number of purifications in the final stage is reduced as compared with Comparative Example 1, but the intermediate substance is also sensitive to external stimuli such as impact and is also subjected to a purification step of explosives. I needed to.

On the other hand, in Example 1, it is clear that the acetylated product of pentaerythritol with high yield and high purity can be easily produced only by a simple operation, and it is a safe and highly productive method. .

Next, Examples 4 to 6 and Comparative Examples 3 and 4 demonstrate the effect of the method for producing a crosslinked polyester resin according to the present invention.

Example 4 Production of Crosslinked Polyester Resin by the Method of the Present Invention Bisphenol A · 2 propylene oxide adduct: 25
0 mmol (86.11 g), isophthalic acid: 240.
2 mmol (39.90 g), and pentaerythritol tetraacetate of Example 1: 25 mmol (7.6
0 g) and the catalyst dibutyltin oxide: 125 mg were placed in a 500 mL round-bottom separable flask, and subjected to a condensation polymerization reaction at 250 ° C. for 8 hours under a nitrogen stream. afterwards,
After further reacting under reduced pressure for 2 hours, the resin was taken out of the reactor onto a Teflon plate, allowed to cool as it was, and the physical properties were evaluated by the methods described below. Table 1 shows the evaluation results.

Example 5: Preparation of crosslinked polyester resin by the method of the present invention Pentaerythritol tetraacetate of Example 1: 2
A polycondensation reaction was carried out in the same manner as in Example 4 except that 5 mmol (7.60 g) was changed to 25 mmol (5.45 g) of trimethylolpropane triacetate obtained in Example 2, to obtain a crosslinked polyester resin. Manufactured. Table 1 shows the results of evaluating the physical properties of this resin.

Example 6: Preparation of crosslinked polyester resin by the method of the present invention Pentaerythritol tetraacetate of Example 4: 2
A cross-linked polyester resin was obtained in the same manner as in Example 3, except that 5 mmol (7.60 g) was replaced with 25 mmol (18.09 g) of pentaerythritol polyoxyethylene adduct tetraacetyl ester of Example 3. Table 1 shows the results of evaluating the physical properties of this resin.

Comparative Example 3 Preparation of Crosslinked Polyester Resin by Conventional Method Pentaerythritol tetraacetate of Example 4: 2
5 mmol (7.60 g) of pentaerythritol: 2
A polycondensation reaction was carried out in the same manner as in Example 4 except that the amount was changed to 5 mmol (3.40 g). As a result, an apparently uneven crosslinked polyester resin was obtained. Table 1 shows the results of evaluating the physical properties of this resin.

Comparative Example 4 Preparation of Crosslinked Polyester Resin by Conventional Method Trimethylolpropane triacetate of Example 5: 2
5 mmol (5.45 g) of trimethylolpropane:
Example 5 except that 25 mmol (3.27 g) was used.
A polycondensation reaction was carried out in the same manner as described above to produce a crosslinked polyester resin. Table 1 shows the results of evaluating the physical properties of this resin.

[Method of Measuring Molecular Weight] The molecular weight of each resin was measured by gel permeation chromatography (GPC).
Method). For GPC measurement, Shodex
Column: "Shodex KF-80M"
While flowing a solvent (THF) at a flow rate of 1 mL / min at a temperature of 25 ° C., 8 mg of a THF solution having a concentration of 0.4 g / dL of the sample resin was converted into a sample weight, and the molecular weight converted into polystyrene was measured. Note that the reliability of this measurement method was determined by using an NBS706 polystyrene standard sample (Mw = 28.
8 × 10 ⁴ , Mn = 13.7 × 10 ⁴ , Mw / Mn = 2.
It confirmed by Mw / Mn of 11) becoming 2.11 ± 0.10.

[Measurement of Glass Transition Temperature] A scanning calorimeter indicating the glass transition temperature of each resin (using a DSC-120 manufactured by Seiko Denshi Kogyo Co., Ltd., a temperature increase of 10 ° C./min and rapid cooling were repeated twice. The glass transition temperature Tg was determined from the endothermic curve at the time of the second temperature increase, where Tg is the value of the midpoint temperature of the endothermic start temperature and the endothermic peak temperature.

[Measurement of Acid Value] The acid value of each resin was measured.
The polyester resin having a crosslinked structure obtained in Examples and Comparative Examples was pulverized using a table mill to obtain 200 mg,
00 mg and 400 mg each in dry THF: 50 mL
And left overnight at room temperature. These polymer solutions were titrated with an N / 100-ethanol solution of potassium hydroxide using a phenolphthalein-ethanol solution as an indicator, and the acid value was calculated by the following equation. The test was performed at five points for each concentration. The results were averaged to determine the acid value (unit: mgKOH / g). Acid value = N / 100 × (factor) × (titer) × 28.05 / (sample weight) Table 1 shows the results of each measurement.

[0063]

[Table 1]

[Evaluation] As shown in Table 1, Examples 4 to 6
As a result, a uniform transparent resin slightly yellowish was obtained, the acid value was 4 or less, and it was confirmed that the reaction proceeded sufficiently and uniformly. On the other hand, comparing the analysis results of Comparative Examples 3 and 4 with Examples 4 and 5, it was confirmed that the Tg was low and the acid value was high, indicating that the reaction did not proceed sufficiently and uniformly. all right.

[0065]

As described above, according to the method for producing a polyacetylated polyhydric alcohol according to the present invention, complicated operations as in the prior art can be omitted, and highly dangerous chemicals and explosives can be exploded. Without the use of
Highly safe, high-purity, high-yield acetylated products of polyhydric alcohols can be easily produced without a purification step.

Further, according to the method for producing a crosslinked polyester resin according to the present invention, by using a polyacetylated product of a polyhydric alcohol, the raw material can be reacted stably and uniformly without a sudden increase in the viscosity of the raw material. Can be.
Therefore, the heterogeneity of the polycondensation reaction observed in the case of producing a crosslinked polyester resin using a polyhydric alcohol can be eliminated, and a uniform reaction can be performed from the beginning of the polycondensation reaction, and a crosslinked polyester resin having stable resin physical properties can be obtained. It can be easily manufactured.

Claims (10)

[Claims] 1. A method for producing a polyacetylated polyhydric alcohol, comprising reacting a trihydric or higher polyhydric alcohol with acetic anhydride under heating without using a solvent other than acetic anhydride. 2. A polyacetylated product of a polyhydric alcohol according to claim 1, wherein the reaction temperature between the trihydric or higher polyhydric alcohol and acetic anhydride is set to 115 ° C. or higher, and acetic acid generated during the reaction is removed. Production method. 3. The method for producing a polyacetylated product of a polyhydric alcohol according to claim 1, wherein the main skeleton of the polyhydric alcohol is a triol having a trimethylol type skeleton. 4. The method for producing a polyacetylated product of a polyhydric alcohol according to claim 1, wherein the main skeleton of the polyhydric alcohol is a tetraol having a neopentyl type skeleton or a tetramethylol skeleton. 5. The polyhydric alcohol according to claim 1, wherein a tertiary amine and / or an acetic acid salt is used as a catalyst when reacting the polyhydric alcohol with acetic anhydride. Method for producing polyacetylated product of polyhydric alcohol. 6. A method for producing a crosslinked polyester resin, wherein a polyacetylated trihydric or higher polyhydric alcohol is used as a component for constructing a crosslinked structure when polycondensing a diol component and a dicarboxylic acid component. . 7. A polyacetylated product of the polyhydric alcohol
Has a main skeleton represented by the following formula:
The method for producing a crosslinked polyester resin according to claim 6. C (-CH_Two—X—O—C (＝ O) —CH_Three)_Four Wherein X is none or ethylene oxide:
-O-CH_Two-CH_Two-, Polyethylene oxide:-｛O
-CH_Two-CH_Two｝_n-, Propylene oxide: -OC
H_Two-CH (CH_Three)-, And polypropyleneoxy
C:-｛O-CH _Two-CH (CH_Three)｝_n-One of
means. N means an integer of 2 or more. 8. The method for producing a crosslinked polyester resin according to claim 6, wherein the polyacetylated product of a trihydric or higher polyhydric alcohol has a main skeleton represented by the following formula. However, wherein X, or Y is a no, ethylene _{oxide: -O-CH 2 -CH 2 -} , polyethylene oxide: -
_{{O-CH 2 -CH 2}} n -, propylene oxide: -O
—CH ₂ —CH (CH ₃ ) — and polypropylene oxide: — {O—CH ₂ —CH (CH ₃ )} _n —, which are not the same as each other. m and m ′ are each an integer of 1 to 3, and m + m ′ = 4. 9. The method for producing a crosslinked polyester resin according to claim 6, wherein the polyacetylated product of a trihydric or higher polyhydric alcohol has a main skeleton represented by the following formula. R—C (—CH ₂ —X—O—C (＝ O) —CH ₃ ) ₃ wherein R represents hydrogen or an organic group having 8 or less carbon atoms, and X represents none or ethylene oxide: -OC
H ₂ —CH ₂ —, polyethylene oxide: — ｛O—CH ₂
—CH ₂ ｝ _n— , propylene oxide: —O—CH ₂ —C
H (CH ₃₎ -, and polypropylene oxide: -
_{{O-CH 2 -CH (CH} 3)} n - represents any.
n means a number of 2 or more. 10. A process for obtaining a polyacetylated product of a polyhydric alcohol by reacting a trihydric or higher polyhydric alcohol with acetic anhydride under heating without using a solvent other than acetic anhydride; By polymerizing a polyacetylated product of an alcohol, a dicarboxylic acid, and a diol,
Obtaining a polyester resin partially having a crosslinked structure introduced therein.