JPH0137408B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention relates to a method for producing polyester elastomer,
In particular, polyester elastomers with good heat resistance can be produced by direct polymerization from dicarboxylic acids mainly composed of aromatic dicarboxylic acids, glycols mainly composed of 1,4-butanediol, and polytetramethylene glycols with a molecular weight of 400 to 6000. Regarding manufacturing methods. [Prior art] Aromatic polyester is used as a hard segment,
Polyester-polyether copolymers with polyalkylene glycol as soft segments, that is, polyester elastomers, are conventional natural rubber,
In recent years, it has been attracting attention as a new thermoplastic elastomer that can replace synthetic rubber. Such polyester elastomers soften at relatively low temperatures and exhibit good fluidity, so they can be economically processed using conventional thermoplastic molding methods (e.g., injection molding and extrusion molding), and at the same time have excellent rubber elasticity and It has many features such as easy adhesion, thermal decomposition resistance, oxidative decomposition resistance, and chemical resistance. Therefore, it is expected to be used in a wide range of applications such as tubes, hoses, belts, tires, films, and elastic yarns. Now, methods for producing polyester elastomers include the so-called direct polymerization method, in which dicarboxylic acid, glycol, and polyalkylene glycol are first subjected to an esterification reaction, and then polycondensed.
A transesterification polymerization method is known, in which dicarboxylic acid diester, glycol, and polyalkylene glycol are first transesterified and then polycondensed, but this method has disadvantages in terms of raw material cost and ease of recovering and reusing by-product tetrahydrofuran. Therefore, the former direct polymerization method is economically advantageous. However, polyester elastomers produced by this direct polymerization method generally have inferior heat resistance compared to polyester elastomers of the same polymer composition produced by transesterification polymerization, and this point is considered a problem in the polyester elastomer field. Ta. Heat resistance here means the ability to maintain strength and elongation properties when the polymer is heated in high-temperature air. [Problems to be Solved by the Invention] The purpose of the present invention is to eliminate the drawbacks of the above-mentioned prior art, and to prevent the heat resistance of polyester elastomers from decreasing due to the economically advantageous direct polymerization method.
Improves retention of strength and elongation properties at high temperatures,
The aim is to have heat resistance equal to or higher than that of polyester elastomers produced by transesterification polymerization. [Means for Solving the Problems] That is, the present invention uses dicarboxylic acids whose main component is aromatic dicarboxylic acids, glycols whose molecular weight is less than 250 whose main component is 1,4-butanediol, and polyesters whose molecular weight is 400 to 6,000. When producing polyester elastomer from tetramethylene glycol by direct polymerization, the raw material has a low fluorine content.
A method for producing a polyester elastomer, characterized in that polytetramethylene glycol is used in an amount of 100 ppm or less, and a polycondensation catalyst and a hindered phenol stabilizer are added after the esterification rate of the dicarboxylic acid reaches 95%. . The polytetramethylene glycol in the present invention has a molecular weight of 400 to 6,000, and may optionally be a copolymer obtained by copolymerizing the polytetramethylene glycol with other components. The molecular weight of polytetramethylene glycol is 400
If it is less than this, the blockness of the resulting polyester elastomer will decrease, resulting in a low polymer melting point. Moreover, if the molecular weight exceeds 6,000, problems such as phase separation of the produced polymer and opacity will occur. Further, the polytetramethylene glycol is generally produced using a fluorine compound such as fluorosulfonic acid as a catalyst, and fluorine-containing compounds caused by these catalysts tend to remain in the polytetramethylene glycol. For this reason, commercially available polytetramethylene glycols often contain far more than 100 ppm of fluorine compounds. In contrast, in the present invention, the fluorine content in polytetramethylene glycol is set to 100 ppm or less, preferably about 50 ppm or less, and more preferably about 30 ppm or less. At this time, if polytetramethylene glycols with a fluorine content exceeding 100 ppm are used, the polymer produced by the direct polymerization method has significantly lower heat resistance at high temperatures than that obtained by the transesterification polymerization method. , and also has the disadvantage that the polymer color becomes darker. In this way, polytetramethylene glycol with a fluorine content of 100 ppm or less can be produced by a method that uses a strong acid catalyst other than fluorine (such as perchloric acid), or when a fluorine-based strong acid catalyst is used, the polymerization reaction is completed. Afterwards, it is obtained by a method of thoroughly washing with an alkaline aqueous solvent to remove fluorine-based impurities. Note that the fluorine content in polytetramethylene glycol can be determined, for example, by the following method. That is,
A sample is burned under pressurized oxygen using an oxygen pump method, the combustion gas is absorbed into an alkaline solution, and the amount of fluorine in this aqueous solution is determined using an ion electrode method. Next, the present invention will be explained in more detail based on embodiments. That is, a dicarboxylic acid whose main component is an aromatic dicarboxylic acid, a glycol with a molecular weight of less than 250 whose main component is 1,4-butanediol, and the polytetramethylene glycol are mixed together with an esterification catalyst, and a stirrer and a rectification column are used. It is charged into the equipped esterification reactor and subjected to an esterification reaction to produce a prepolymer. The dicarboxylic acid used in the present invention is a dicarboxylic acid containing 50 mol% or more of aromatic dicarboxylic acid, and aromatic dicarboxylic acids include terephthalic acid, isophthalic acid, phthalic acid, 2,6-naphthalene dicarboxylic acid, , 5-naphthalene dicarboxylic acid, 1,2-bis(phenoxy)ethane p, p'-
Dicarboxylic acids, diphenyl p, p'-dicarboxylic acids, and the like are preferably used. Among these aromatic dicarboxylic acids, terephthalic acid and isophthalic acid are particularly preferably used. Furthermore, aliphatic dicarboxylic acids such as succinic acid, adipic acid, sebacic acid, 1,4-cyclohexanedicarboxylic acid, and 1,3-cyclohexanedicarboxylic acid, or alicyclic dicarboxylic acids can also be used in an amount of less than 50 mol %. Furthermore, the glycol used in the present invention includes 1,
Glycols containing 70 mol% or more of 4-butanediol and having a molecular weight of less than 250, such as ethylene glycol, 1,3-propanediol, 1,6-
Less than 30 mol% of a primary diol compound such as hexanediol, diethylene glycol, triethylene glycol, 1,4-cyclohexanedimethanol, etc. may be used in combination. In addition to the aromatic dicarboxylic acids and glycols, copolymerization components include oxycarboxylic acids such as p-(β-hydroxyethoxy)benzoic acid and p-oxymethylbenzoic acid, trifunctional acids such as trimellitic acid, trimesic acid, and pyromellitic acid. A small amount of the above polyhydric carboxylic acids can also be used. The molar ratio of glycol to dicarboxylic acid is
It is preferably 1.3 or more and 2.2 or less, particularly preferably 1.6 or more and 2.2 or less. In addition, the weight percent of the repeating unit consisting of the polytetramethylene glycol component and the dicarboxylic acid component, that is, the soft segment unit, with respect to the produced polymer
can be selected as appropriate depending on the required elastic properties of the polyester elastomer, but generally it is 10 to 80.
The amount is approximately 15 to 70% by weight, particularly preferably approximately 15 to 70% by weight. Esterification catalysts include tetraalkyl titanates, reaction products of tetraalkyl titanates and alkylene glycols, partial hydrolysates of tetraalkyl titanates, metal salts of titanium hexaalkoxide, titanium carboxylates, titanyl compounds, etc. Titanium compounds, as well as tin compounds such as dialkyltin oxide, dialkyltin sulfide, monoalkylhydroxytin oxide, trialkyltin hydroxide, triaryltin hydroxide, and mixtures thereof are used. The amount of the esterification catalyst added is preferably about 0.01 to 0.5% by weight, particularly 0.03 to 0.5% by weight, based on the produced polymer.
About 0.2% by weight is preferable. The esterification reaction is usually carried out under normal pressure by gradually increasing the temperature from around 150°C to 220-240°C, and distilling off the produced water and tetrahydrofuran through a rectification column. The time for the esterification reaction is influenced by the raw material composition of the reaction system, catalyst species, catalyst amount, reaction temperature, etc., but is generally about 2 to 7 hours. After the esterification reaction is completed, a polycondensation catalyst, a hindered phenol stabilizer, etc. are added, and the reaction product is then transferred to a polycondensation reactor and polymerized at 230 to 260°C for several hours under a high vacuum of 1 mmHg or less. Condensation is performed to obtain a polyester elastomer having a desired degree of polymerization. What is particularly important here is that the esterification reaction has progressed by at least 95%, preferably at least 97%, by the time the polycondensation catalyst and hindered phenol stabilizer are added. This esterification reaction rate is 95%
If a polycondensation catalyst or hindered phenol stabilizer is added at a point below This will cause inconveniences such as higher prices. Note that there is no problem in adding these polycondensation catalysts and hindered phenol stabilizers after the esterification reaction product is transferred to the polycondensation reactor. As the polycondensation catalyst in this case, the titanium compounds mentioned above as examples of the esterification catalyst are preferably used. Furthermore, it is also preferable to use alkaline earth metals such as magnesium and calcium in combination with these titanium compounds. The amount of the polycondensation catalyst added is generally preferably about 0.03 to 0.30% by weight based on the produced polymer. Further, as the hindered phenol stabilizer, the following compounds can be exemplified. Further, hindered phenols having a thioether bond, hindered phenols having an amide bond, etc. can be used. The amount of the hindered phenol stabilizer added is generally preferably about 0.03 to 0.60% by weight based on the produced polymer. [Effect of the invention] The polyester elastomer thus obtained has heat resistance equal to or higher than that of the polymer produced by the transesterification polymerization method, has a good polymer color tone, and has a higher heat resistance than the polymer produced by the transesterification polymerization method. It is advantageous in terms of manufacturing costs, especially raw material costs. Moreover, the polyester elastomer is a tube,
It is widely used in hoses, belts, sporting goods, electrical parts, automobile parts, elastic fibers, etc. Hereinafter, the present invention will be explained in more detail with reference to Examples. Note that the polymer properties in this example were measured by the following method. (1) Relative viscosity Dissolve 8 g of polymer in 100 ml of orthochlorophenol (dissolution conditions: 100°C, approximately 1 hour), allow to cool, and measure at 25°C using an Ostwald viscometer. (2) Solution haze After dissolving 5.4 g of polymer in 40 ml of a mixed solvent of phenol and tetrachloroethane (mixing ratio 6:4) (dissolution conditions: 100°C, approximately 1 hour), let it cool and conduct colorimetry using integrating sphere turbidity. Meter (Nippon Seimitsu Kogaku, type SEP-H)
-2) and measure in a 30 mm glass cell. Solution haze (%) can be calculated from the following formula. Solution haze (%) = (diffuse transmitted light/total transmitted light) x 100 This solution haze was used as an index of the transparency of the polymer in its molten state and solution state. (3) Polymer color tone Using a cylindrical chip sample, a Hunter-type automatic color difference meter [manufactured by Toyo Rika Kogyo Co., Ltd.] was used to determine the L value (the larger this value, the brighter the lightness), the a value (the larger the value, the more reddish the (larger) and L value (the larger the value, the greater the yellowness). Note that parts are parts by weight. Examples 1 to 5, Comparative Examples 1 to 3 54.2 parts of terephthalic acid, 1,4-butanediol
52.9 parts of polytetramethylene glycol with a molecular weight of 1000 (fluorine content listed in Table 1), 31.0 parts of tetrabutyl titanate, and 0.04 parts of tetrabutyl titanate were charged into an esterification reactor equipped with a rectification column and a stirrer, and heated at 160°C.
The esterification reaction was carried out while gradually increasing the temperature from 230°C to 230°C, and the resulting water and tetrahydrofuran were distilled off through a rectification column. The esterification reaction time is
It took 3.5 to 4.0 hours. After the esterification reaction, 0.10 parts of tetrabutyl titanate as a polycondensation catalyst was dissolved in a small amount of 1,4-butanediol, and 0.20 parts of a stabilizer "IRGANOX1010" (manufactured by Ciba-Geigy) was added in a small amount. It was added after being suspended in 1,4-butanediol. Table 1 shows the esterification reaction rate at the time when the polycondensation catalyst and stabilizer were added. Next, the esterification reaction product was transferred to a polycondensation reactor, and the pressure was gradually reduced from normal pressure to 1.0 mmHg or less over 1 hour, and at the same time the temperature was raised to 245°C.
Polycondensation was carried out for 3.0 hours at ℃ and 1.0 mmHg or less. Table 1 shows the heat resistance (heat resistance life) and other polymer properties of the produced polymer. As shown by these results, the produced polymers of Examples 1 to 5, which use polytetramethylene glycol with a fluorine content of 100 ppm or less as a raw material, have good heat resistance and polymer color tone, and have a low fluorine content.
The produced polymers of Examples 1 and 2, which use 50 ppm or less of polytetramethylene glycol, have particularly good heat resistance. The polymers produced in Comparative Examples 1 and 2 in which the fluorine content in polytetramethylene glycol exceeded 100 ppm had extremely poor heat resistance, and the polymer color tone was dark (low L value).
It is defective. Comparative Example 3 in which the esterification reaction rate upon addition of the polycondensation catalyst and stabilizer was less than 95% (94%).
Even though the fluorine content in polytetramethylene glycol is less than 100 ppm, the produced polymer is
The heat resistance was low, and the transparency of the polymer was also poor.

[Table] Examples 6 to 10, Comparative Examples 4 to 6 38.4 parts of terephthalic acid, 12.8 parts of isophthalic acid,
55.4 parts of 1,4-butanediol, polytetramethylene glycol with a molecular weight of 1000 (the fluorine content was
35.4 parts (listed in the table) and 0.04 parts of tetrabutyl titanate are charged into an esterification reactor equipped with a rectification column and a stirrer, and the esterification reaction is carried out while the temperature is gradually raised from 160°C to 230°C. The water produced and tetrahydrofuran were distilled off through a rectification column. The esterification reaction time was 3.5 to 4.0 hours. After the esterification reaction, 0.10 part of tetrabutyl titanate as a polycondensation catalyst was dissolved in a small amount of 1,4-butanediol and added, and 0.20 part of a stabilizer "IONOX330" (manufactured by Ciel Chemical Co., Ltd.) was added in a small amount of 1,4-butanediol. It was suspended in 4-butanediol and added. Table 2 shows the esterification reaction rate at the time when the polycondensation catalyst and stabilizer were added. Next, the esterification reaction product was transferred to a polycondensation reactor, and the pressure was gradually reduced from normal pressure to 1.0 mmHg or less over 1 hour, and at the same time the temperature was raised to 245°C.
Polycondensation was carried out for 3.0 hours at ℃ and 1.0 mmHg or less. Table 1 shows the heat resistance (heat resistance life) and other polymer properties of the produced polymer. As shown by these results, the produced polymers of Examples 6 to 10, which use polytetramethylene glycol with a fluorine content of 100 ppm or less as a raw material, have good heat resistance and polymer color tone, and have a low fluorine content.
The polymers produced in Examples 6 and 7, which use less than 50 ppm of polytetramethylene glycol, have particularly good heat resistance. The polymers produced in Comparative Examples 4 and 5, in which the fluorine content in polytetramethylene glycol exceeded 100 ppm, had extremely poor heat resistance, and the polymer color tone was dark (low L value). Furthermore, the produced polymer of Comparative Example 6, in which the esterification reaction rate upon addition of the polycondensation catalyst and stabilizer was less than 95% (94.3%), was found to have a fluorine content of less than 100 ppm in polytetramethylene glycol. figure,
The heat resistance was low, and the transparency of the polymer was also poor.

【table】

Claims (1)

[Claims] 1 Dicarboxylic acid whose main component is aromatic dicarboxylic acid, glycol with a molecular weight of less than 250 and whose main component is 1,4-butanediol, and a molecular weight of 400 to 6000
When producing polyester elastomer from polytetramethylene glycol by direct polymerization method, polytetramethylene glycol with a fluorine content of 100 ppm or less is used as a raw material, and
A method for producing a polyester elastomer, which comprises adding a polycondensation catalyst and a hindered phenol stabilizer after the esterification rate of the dicarboxylic acid reaches 95%.