JPH10330466A - Production of polyester resin - Google Patents

Abstract

PROBLEM TO BE SOLVED: To produce the subject resin, having a low carboxyl end group concentration and excellent heat and hydrolytic resistances and useful as an automotive part, etc., by adding a small amount of a boric acid compound into a polycondensation step for a polyester. SOLUTION: The polycondensation is carried out by adding a boric acid compound, preferably at least one selected from orthoboric acid, metaboric acid, tetraboric acid, etc., so as to provide 0.005-5 wt.% amount thereof based on the finally obtained polyester resin in an optional period till the completion of the polycondensation step when producing a polyester resin. The polyester resin is preferably mixed with the boric acid compound in a molten state for >=3 min and the polyester resin is preferably produced from an aromatic dicarboxylic acid consisting essentially of terephthalic acid or its derivative and a diol consisting essentially of 1,4-butanediol as raw materials.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for producing a polyester resin, and more particularly, to a method for producing a polyester resin having a small number of carboxyl terminals.

[0002]

BACKGROUND OF THE INVENTION Polyester resins, especially polyethylene terephthalate (hereinafter referred to as "polyethylene terephthalate")
PET), polybutylene terephthalate (hereinafter, referred to as PET)
PBT), polybutylene naphthalate (hereinafter referred to as P
Polyester resins composed of an aromatic dicarboxylic acid represented by BN) and a diol component have excellent mechanical properties, physical and chemical properties, and good processing properties such as injection molding and extrusion molding. Therefore, it is widely used as an engineering plastic in automobiles, electric / electronic parts, other precision machines, building materials, miscellaneous goods, and the like. However, with the expansion and diversification of applications, there are increasing cases where stability of physical properties (moisture and heat resistance) for long-term use under high temperature and high humidity is required. For example, for automotive parts, due to safety needs,
There is a strong demand for improvement in mechanical property reduction due to molecular weight reduction due to hydrolysis, thermal decomposition, and the like. In general, it is known that deterioration of a polyester resin due to wet heat is largely caused by hydrolysis of a polyester chain, and this hydrolysis reaction largely depends on the content of the carboxyl terminal of the polyester itself. It is also known that aromatic polyester resins such as PET, PBT, and PBN have better moist heat resistance as the carboxyl terminal is smaller, and PET and PB having a reduced carboxyl terminal to improve wet heat resistance.
Various methods for producing a polyester resin comprising an aromatic dicarboxylic acid component and a diol component such as T and PBN have been proposed. For example, a method of adding a compound having reactivity with a carboxyl terminal such as an epoxy compound to block the carboxyl terminal, a method of adding a basic compound such as sodium hydroxide or potassium hydroxide to neutralize the carboxyl terminal. However, there are problems such as insufficient effect and coloring.

[0003]

Means for Solving the Problems In order to solve the above problems,
As a result of intensive studies, the present inventors have found that a polyester resin having a low carboxyl terminal concentration can be obtained by adding a small amount of a boric acid compound during the polyester polycondensation step. It has been reached. That is, the present invention relates to the production of a polyester resin, at any time before the end of the polycondensation step, the boric acid compound is added to the finally obtained polyester resin in 0.00.
This is a method for producing a polyester resin, wherein a polycondensation reaction is carried out by adding so as to be 5 to 5% by weight.

[0004]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail.
The polyester resin in the present invention is a polyester resin comprising an acid component mainly composed of an aromatic dicarboxylic acid and a diol component.In addition to the dicarboxylic acid and the diol component, as a raw material monomer for forming a main skeleton,
It is also possible to use their ester-forming derivatives. Here, specific examples of the aromatic dicarboxylic acid include terephthalic acid, isophthalic acid, phthalic acid, naphthalenedicarboxylic acid, biphenyldicarboxylic acid, stilbenedicarboxylic acid, and 2,2- (biscarboxyphenyl) propane. Examples of the ester-forming derivatives include lower alcohol esters thereof.
In the present invention, one or more of the above-described aromatic dicarboxylic acid components are used. Next, as the diol component,
Ethylene glycol, propylene glycol, 1,4-butanediol, diethylene glycol, triethylene glycol, neopentyl glycol, hydroquinone,
Examples thereof include dihydroxyphenol, cyclohexanediol, cyclohexanedimethanol, naphthalene diol, dihydroxydiphenyl ether and the like, and alkyl, alkoxy or halogen-substituted products thereof, and one or more of these are used. Further, in the present invention, other dicarboxylic acids and / or diols and oxycarboxylic acids can be used as a copolymer component as long as the original properties are not impaired. Examples of other dicarboxylic acids include known dicarboxylic acids such as cyclohexanedicarboxylic acid, adipic acid, and sebacic acid, but are not particularly limited. These dicarboxylic acid compounds can also be used for copolymerization in the form of a derivative capable of forming an ester, for example, a lower alcohol ester such as dimethyl ester. In addition, two or more of these may be used. Other diol components include resorcinol and 2,2-
There are dihydroxy compounds such as bis (4-hydroxyphenyl) propane and diethoxylated bisphenol A, and substituted products thereof, and one or more kinds can be used. In addition, the components of oxycarboxylic acid include oxybenzoic acid, oxynaphthoic acid, diphenyleneoxycarboxylic acid and substituted products thereof, and one or more of these may be used. Further, in addition to these, a polyester having a branched or crosslinked structure obtained by copolymerizing a small amount of trifunctional monomers, that is, trimellitic acid, trimesic acid, pyromellitic acid, pentaerythritol, trimethylolpropane, etc., within a range not impairing the original characteristics. It may be a resin. The amount of these copolymer components introduced is
Preferably 30 mol% based on all constitutional repeating ester units
Or less, and particularly preferably 20 mol% or less, but is not particularly limited. In the present invention, among the polyester resins as described above, a PET resin mainly containing terephthalic acid and ethylene glycol as main components, and a PBT resin mainly containing terephthalic acid and 1,4-butanediol as main components And naphthalenedicarboxylic acid (especially
The effect of suppressing the carboxyl terminal in a PBN-based resin containing 2,6-form) and 1,4-butanediol as main components is remarkable.

In the present invention, the boric acid compound added during the polycondensation step in order to suppress the formation of a carboxyl terminal includes boric acids such as orthoboric acid, metaboric acid and tetraboric acid, and oxidation of diboron trioxide and the like. Examples include borons, metal salts of boric acid, and boric esters with alcohol compounds and phenol compounds. Among them, orthoboric acid, metaboric acid, tetraboric acid and diboron trioxide, alkali metal salts of boric acid (potassium metaborate, sodium tetraborate, etc.) and alkaline earth metal salts (magnesium orthoborate, barium orthoborate, etc.) , Borate esters [C ₁
-C ₁₂ aliphatic monoalcohols, polyhydric alcohols (ethylene glycol, tetramethylene glycol, glycerol, pentaerythritol, etc.), phenolic compounds (phenol, catechol, resorcinol, hydroquinone, cresol, etc.) of boric acid mono-, di-, tri-, Alternatively, a tetraester compound, a mixture thereof, and a metal salt thereof] have high effects and are preferably used. The particle size of the boric acid compound to be used is not particularly limited, but in the case of diboron trioxide or borate, the smaller the particle size, the better the effect and the size of 10 μm or less is preferably used. The amount of the boric acid compound to be added is 0.005 to 5% by weight, preferably 0.01 to 3% by weight, based on the finally obtained polyester resin. The boric acid compound can be added at any time from the end of the transesterification or esterification step to the end of the polycondensation step. Preferably, when the boric acid compound is mixed with the polyester resin in a molten state for 3 minutes or more, particularly preferably 10 minutes or more, a more remarkable effect is obtained. It is also possible to add the boric acid compound at any stage in several steps. When added to the esterification or transesterification step and when added after the completion of the polycondensation step, the effect of reducing the carboxyl terminal is small.

In the method of the present invention, for example, a lower alcohol ester of terephthalic acid or naphthalenedicarboxylic acid is used as an acid component, and 1,4-
In the transesterification reaction using butanediol, a lower alcohol ester of terephthalic acid or naphthalenedicarboxylic acid and 1,4-butanediol are used in a molar ratio of 1: 1 to 1: 1.
The ratio is set to 1: 2 at 140 to 230 ° C. under normal pressure while continuously removing by-product lower alcohol. As a catalyst for obtaining a practical reaction rate, a titanium compound,
Tin compounds, lead oxide, lead acetate, zinc acetate, zinc oxide, manganese acetate and the like are exemplified. Among them, organic titanate compounds, titanium tetrachloride compounds and their hydrolyzates or alcoholysis products, tin oxide, tin acetate, Organotin compounds and the like are preferred. Specifically, tetrabutyl titanate, tetrapropyl titanate, tetraethyl titanate, tetramethyl titanate and their hydrolysates, hydrolysates such as titanium tetrachloride and titanium sulfate, titanium fluoride potassium, titanium zinc fluoride, titanium cobalt fluoride and the like Known titanium compounds and / or dibutyltin oxide, dibutyltin acetate, diphenyltin lauryl mercaptide, dibutyltin sebacate, dibutyltin ethylene glycolate, dioctyltin salicate as a catalyst for the production of polyesters such as inorganic titanium compounds, titanium oxalate, potassium oxalate, etc. Conventionally known tin compounds are exemplified as catalysts for the production of polyesters such as acrylate, diphenyltin benzenesulfonate and dimethyltin-p-toluenesulfonate. Particularly preferred are tetrabutyl titanate, tetrapropyl titanate, hydrolysates of titanium tetrachloride, dibutyltin oxide, dibutyltin acetate, dioctyltin acetate, and the like. The amount of these catalysts used is preferably 10 to 1200 ppm (to the polymer) as titanium and tin (in the case of a mixture system), particularly preferably titanium compound, tin compound and a mixture thereof when titanium compound and tin compound are used. Is preferably 30 to 1000 ppm (based on the polymer), and if necessary, it can be added in several portions during the reaction.

The esterification reaction using terephthalic acid or naphthalenedicarboxylic acid as the main raw material as the acid component is carried out at a ratio of 1 to 5 mol of 1,4-butanediol to 1 mol of terephthalic acid or naphthalenedicarboxylic acid. , 180
The reaction is carried out at -250 ° C. under normal pressure or under pressure, while adding an esterification reaction catalyst such as the above-mentioned titanium compound or tin compound to remove continuously generated water. The catalyst can be divided into several times during the reaction, if necessary.

In the polycondensation reaction, the product obtained by the above-mentioned transesterification or esterification reaction is obtained by reducing the pressure of the reaction system at 190 to 270 ° C. and continuously removing excess 1,4-butanediol and reaction by-products. Melt polymerization is performed until a desired degree of polymerization is obtained. As the catalyst for obtaining a practical reaction rate in the polycondensation reaction, the catalyst used in the above-mentioned transesterification reaction or esterification reaction can be used as it is, and in order to improve the rate of the polycondensation reaction, the catalyst is used. It is also possible to add one or more of these before starting the condensation reaction. It is also possible to add a conventionally known stabilizer such as a sterically hindered phenol or a phosphorus compound to the monomer preparation step or the polymerization step. It should be noted that the boric acid compound added in the present invention does not slow down the polycondensation reaction rate in the addition amount specified in the present invention. The polyester resin of the present invention obtained by the above melt polymerization has an intrinsic viscosity at 25 ° C. of ortho-chlorophenol of about 0.5 to 1.2 dl / g. After being taken out, it is cooled, solidified, pulverized or pelletized. You. In particular, when a high degree of polymerization is required, it is possible to shift to solid-phase polymerization depending on the application. The solid-phase polymerization is generally performed by a known method, and a desired degree of polymerization can be appropriately adjusted by a residence time, a treatment temperature, and the like.

The polyester resin produced according to the present invention may be supplemented with one or more of other thermoplastic resins, additives, organic fillers, inorganic fillers and the like during or after polymerization, if necessary. Can also be used as a composition added and blended. Here, examples of the thermoplastic resin include polyester elastomers and polyester resins other than the present invention, polyolefin resins, polystyrene resins, polyamide resins, polycarbonates, polyacetals, polyarylene oxides, polyarylene sulfides, and fluororesins. Further, as additives, stabilizers such as conventionally known ultraviolet absorbers and antioxidants, antistatic agents, flame retardants, flame retardant aids, coloring agents such as dyes and pigments, lubricants, plasticizers, lubricants, A release agent, a crystal nucleating agent and the like are exemplified. In addition, as the filler, glass fiber, milled glass fiber,
Silicates such as glass beads, glass flakes, silica, alumina fibers, zirconia fibers, potassium titanate fibers, carbon fibers, carbon black, graphite, calcium silicate, aluminum silicate, kaolin, talc, clay,
Metal oxides such as iron oxide, titanium oxide, zinc oxide, antimony oxide, and alumina; carbonates and sulfates of metals such as calcium, magnesium, and zinc; and silicon carbide, silicon nitride, and boron nitride. Examples of the filler include high melting point aromatic polyester fibers, liquid crystalline polyester fibers, aromatic polyamide fibers, fluororesin fibers, and polyimide fibers. When used as a molded article for electric / electronic parts or automobile parts, there are many cases where flame retardancy is required depending on the usage environment, and there are many cases where the blending of flame retardants and flame retardant aids is essential. It is often necessary to add a flame retardant and a flame retardant auxiliary. As the flame retardant, known halogen-containing compound-based flame retardants such as brominated polycarbonate, brominated epoxy compound, brominated diphenyl, and brominated diphenyl ether can be used.As the flame retardant aid, antimony trioxide, antimony pentoxide, In addition to antimony compounds such as antimony halides, metal compounds containing zinc and bismuth, and viscous silicates such as magnesium hydroxide and asbestos can be used.

[0010]

Industrial Applicability The polyester resin produced according to the present invention has excellent heat resistance and hydrolysis resistance due to reduced carboxy terminals, and is especially used for industrial resin parts such as automobile parts, electric / electronic parts and the like. Can be suitably used.

[0011]

EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples, but the present invention is not limited to these examples. Example 1 A reactor equipped with a stirrer and a distillation column was sufficiently purged with nitrogen, and 246 parts by weight of dimethyl terephthalate, 145 parts by weight of 1,4-butanediol, and 0.16 parts by weight of titanium tetrabutoxide as a catalyst were charged. A transesterification reaction was carried out, and the temperature was gradually raised to remove by-produced methanol. When the distilled methanol exceeds 88% by weight of the theoretical amount, the temperature of the reactant is raised to 200 ° C., and then transferred to another reactor equipped with a stirrer, a distilling column and a dropping funnel.
The pressure was reduced to 0.5 Torr over time, and the reaction temperature was raised to 250 ° C at the same time. After stirring for 1 hour and 15 minutes in this state, 0.2 parts by weight of orthoboric acid was slurried with 2.8 parts by weight of cyclohexane. After adding to the reactor and continuing stirring for further 15 minutes, the melt was taken out as a strand from the outlet, the strand was cooled with water, and attached water was removed under hot air to obtain a PBT resin in the form of pellets. The concentration of carboxyl end groups was measured. [Concentration of carboxyl end group] 0.2 g of the obtained PBT resin was dissolved in 20 ml of benzyl alcohol at 215 ° C., and the solution was measured by titration with a 0.01 N sodium hydroxide solution. Example 2 Except that the amount of orthoboric acid was changed to 0.56 parts by weight,
Polymerization was carried out in the same manner as in Example 1 to obtain a PBT resin, and the concentration of the carboxyl terminal group was measured in the same manner. Table 1 shows the results. Example 3 Polymerization was carried out in the same manner as in Example 1 except that the stirring time under reduced pressure after the addition of orthoboric acid was 5 minutes to obtain a PBT resin, and the concentration of the carboxyl terminal group was measured in the same manner. Table 1 shows the results
Shown in

Comparative Example 1 A PBT resin was obtained by polymerization in the same manner as in Example 1 except that orthoboric acid was not added, and the concentration of carboxyl end groups was measured in the same manner. Table 1 shows the results. Comparative Example 2 Orthoboric acid was added to the PBT resin pellets obtained in Comparative Example 1 in an amount of 0.20% by weight and melt-kneaded with a small twin-screw extruder to prepare pellets. The carboxyl terminal group concentration of the obtained PBT resin was measured in the same manner as in Example 1. Table 1 shows the results.

[0013]

[Table 1]

Claims (6)

[Claims] In producing a polyester resin, a boric acid compound is added at an arbitrary time until the end of the polycondensation step so as to be 0.005 to 5% by weight with respect to the finally obtained polyester resin. A method for producing a polyester resin, comprising performing a condensation reaction. 2. The polyester resin according to claim 1, wherein the boric acid compound is at least one selected from orthoboric acid, metaboric acid, tetraboric acid, diboron trioxide, metal salts of boric acids, and borate esters. Manufacturing method. 3. The method for producing a polyester resin according to claim 1, wherein the polyester resin and the boric acid compound are mixed in a molten state for 3 minutes or more. 4. The method for producing a polyester resin according to claim 1, wherein the polyester resin is made from an aromatic dicarboxylic acid or a derivative thereof and a diol. 5. The method for producing a polyester resin according to claim 4, wherein the aromatic dicarboxylic acid is mainly composed of terephthalic acid or a derivative thereof. 6. The method for producing a polyester resin according to claim 4, wherein the diol is mainly composed of 1,4-butanediol.