JP3374544B2 - Method for producing polyester copolymer - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a process for producing a polyester copolymer which is useful as a thermoplastic elastomer having good thermal stability in a molten state.

[0002]

2. Description of the Related Art Copolyesters containing a polytetramethylene ether glycol component have excellent heat resistance and oil resistance as elastomers, and have recently been mainly used because of their ease of injection molding. ,
It has become useful for automobiles. However, when this copolyester is maintained in a molten state, decomposition products are generated due to insufficient thermal stability. This decomposition product is gaseous and often enters the polymer as air bubbles, which often causes defects such as poor shape in the subsequent pelletizing, compounding and injection molding processes. It is desirable to suppress the generation of objects. In particular, during production, after completion of the polycondensation reaction, when the polymer is pelletized, in the polymer held in the molten state, the gas generation of the decomposition product tetrahydrofuran increases as the holding time increases, There was a problem that pelletization became impossible when the shape of the pellet was deteriorated due to gas bubbles and the amount of decomposition products was increased. Further, the amount of terminal carboxyl groups increases due to the decomposition of the ester bond during the retention, and the hydrolysis resistance of the polymer decreases. For this reason, there is a limit to the amount of one-time production, the type of pelletizer, the ability, etc.

[0003]

Means for Solving the Problems As a result of intensive studies, the present inventors have made an alkali metal hypophosphite present in a molten polymer to suppress the generation of gas and improve the thermal stability of the polymer. The inventors have found what can be done and have reached the present invention. That is, according to the present invention, an aliphatic and / or alicyclic diol having 2 to 12 carbon atoms and a molecular weight of 500 to 60
No. 00 polytetramethylene ether glycol and an aromatic dicarboxylic acid or its alkyl ester as a raw material, and a polyester copolymer in a molten state by polycondensing an oligomer obtained by an esterification reaction or a transesterification reaction. In the case where the polymer is produced and then shaped into an appropriate shape, the presence of 1 to 1000 ppm of an alkali metal hypophosphite in the polymer in the molten state can improve the thermal stability in the molten state. Therefore, it is possible to avoid deterioration of the shape of the pellet obtained by solidifying the pellet. Moreover,
It is possible to produce a polymer having a small amount of terminal carboxyl groups and good hydrolysis resistance.

The present invention will be described in detail below. As the aliphatic or alicyclic diol having 2 to 12 carbon atoms used in the present invention, those known as a raw material of polyester, particularly a raw material of polyester elastomer can be used, and examples thereof include ethylene glycol, propylene glycol and trimethylene glycol. , 1,4-butanediol, 1,4
-Cyclohexanediol, 1,4-cyclohexanedimethanol and the like are preferable, 1,4-butanediol and ethylene glycol are particularly preferable, and 1,
It has 4-butanediol as a main component, and one kind or two or more kinds can be used.

As the aromatic dicarboxylic acid, those known as raw materials for polyester, particularly polyester elastomer, can be used, and terephthalic acid, isophthalic acid,
Examples thereof include phthalic acid and 2,6-naphthalenedicarboxylic acid, preferably terephthalic acid and 2,6-naphthalenedicarboxylic acid, and particularly preferably those containing terephthalic acid as a main component. You may use together the above. Examples of the alkyl ester of aromatic dicarboxylic acid include dimethyl terephthalate, dimethyl isophthalate, dimethyl phthalate, and 2,6-dimethyl naphthalate. Dimethyl terephthalate and 2,6-dimethyl naphthalate are preferable. Yes, and particularly preferably, dimethyl terephthalate, and two or more of these can be used in combination.
In addition to the above, small amounts of trifunctional diols, other diols and other dicarboxylic acids and their esters may be copolymerized, and further, aliphatic or alicyclic dicarboxylic acids such as adipic acid, or alkyls thereof. Esters may also be used as a copolymerization component.

Polytetramethylene ether glycol has a weight average molecular weight (hereinafter simply referred to as "molecular weight") of 50.
The one having a molecular weight of 650 to 3 is used.
000 is desirable, particularly preferably 800-25
00. When the molecular weight is less than 500, the block property of the copolymer is insufficient, and when the molecular weight exceeds 6000, the physical properties of the polymer deteriorate due to phase separation in the system.

The content of polytetramethylene ether glycol is preferably 5 to 95% by weight, and more preferably 20 to 80% by weight based on the polymer produced. If the content is less than 5%, the characteristics as a copolymer cannot be obtained, and if the content exceeds 95%, it is difficult to obtain a polymer by polycondensation. Examples of the alkali metal hypophosphite include sodium hypophosphite, potassium hypophosphite, lithium hypophosphite and the like, and sodium hypophosphite is particularly desirable. The amount of addition in this molten polymer is 1 to 1 with respect to the polymer produced.
000 ppm, more preferably 3 to 200 ppm, particularly preferably 5 to 80 ppm. 1 ppm
If less than 1,000, the effect of addition is not sufficiently obtained,
Addition of more than ppm is not preferable because the effect does not change and the polycondensation reaction is hindered. As an addition method, an alkali metal hypophosphite salt solution, slurry,
It may be added to the molten polymer in any solid state, and the addition time is preferably at least before the end of the polycondensation reaction, that is, before the esterification reaction or before the ester exchange reaction and before the end of the polycondensation, It may be added at any time. In particular, it is preferable to add it in the form of a slurry immediately before the start of the polycondensation under reduced pressure, since the polymerizability is not lowered.

The esterification, transesterification and polycondensation reaction in the present invention can be carried out according to a conventional method. As catalysts in these reactions, one or two or more known catalysts such as alcoholates such as tin, titanium, zinc and manganese, chlorides and oxides can be used, respectively. Catalysts, especially tetrabutyl titanate, are desirable. In addition, phosphoric acid, phosphorous acid, or metal salts thereof may be added as an auxiliary agent.

Further, other additives may be present in the reaction step. For example, in addition to a hindered phenol-based oxidation stabilizer, a hindered amine-based oxidation stabilizer, a phosphorus-based oxidation stabilizer, a sulfur-based oxidation stabilizer, a triazole-based light resistance stabilizer, and other known additives are used. Particularly, in the present invention, it is more preferable to add the hindered phenol-based oxidation stabilizer in an amount of 0.01 to 1% by weight with respect to the polymer in terms of the effect. The esterification or transesterification reaction is usually performed at 120 to 250 ° C., preferably 150 to 230 ° C., and the melt polycondensation reaction is usually performed at 200 to 280 ° C. for 2 to 6 hours under reduced pressure of 10 torr or less. Normal,
The polymer obtained by melt polycondensation is maintained at a temperature equal to or higher than the melting point, and is sequentially discharged from the reaction can and subjected to molding such as pelletizing. The pellets obtained here may be further solid-phase polymerized, if necessary.

[0010]

The present invention will be described in more detail with reference to the following examples, but the present invention is not limited to these examples as long as the gist thereof is not exceeded.

Example 1 60 parts by weight of dimethyl terephthalate, 31 parts by weight of 1,4-butanediol and 35 parts by weight of polytetramethylene ether glycol (average molecular weight 1000) were used to produce tetrabutyl titanate as a catalyst in terms of metallic titanium. 200ppm added to the polymer
A transesterification reaction is carried out at 230 ° C. for 3.5 hours, and then sodium hypophosphite monohydrate is added to the produced polymer at 50 ppm, a hindered phenol-based oxidation stabilizer [Ciba Geigy Co., Ltd. product, Product Name: Irgan
ox1010] 0.18 part by weight was added, and melt polycondensation was performed at 230 ° C. to 245 ° C. under reduced pressure of 3 torr or less to produce a polyester copolymer.

1 g of this polymer was dissolved in 100 ml of a solvent in which phenol and tetrachloroethane were mixed at a ratio of 1: 1, and the solution viscosity [η] at 30 ° C. was measured.
Further, when this polymer was held in a glass container at 245 ° C. in a nitrogen atmosphere, the time until bubbles were generated in the liquid phase was visually determined. The pressure cooker test showing the hydrolysis resistance was shown by the retention rate of the solution viscosity before and after being placed in a pressure cooker at 120 ° C. for 96 hours. Moreover, the amount of terminal carboxyl groups was measured under the following conditions. That is, it is a value obtained by dissolving the polymer in benzyl alcohol and titrating it with 0.1 N sodium hydroxide, and is indicated by the equivalent amount per 10 ⁶ g (1 t).

Example 2 A polymer was produced in the same manner as in Example 1 with respect to 32 parts by weight of dimethyl terephthalate, 20 parts by weight of 1,4-butanediol and 70 parts by weight of polytetramethylene ether glycol (average molecular weight 2000). The evaluation results are shown in Table 1.

Example 3 49 parts by weight of terephthalate and 1,4-butanediol 4
To 9 parts by weight and 35 parts by weight of polytetramethylene ether glycol (average molecular weight 1000), 100 ppm of tetrabutyl titanate was added as a catalyst to the polymer produced in terms of metallic titanium, and esterified at 210 ° C to 225 ° C for 4 hours. I went. Then, sodium hypophosphite monohydrate is added to the produced polymer at 50 pp.
m, hindered phenol-based oxidation stabilizer [Ciba Geigy Co., Ltd. product, trade name: Irganox 1010]
18 parts by weight was added, and the pressure was reduced to 3 torr or less at 225 ° C.
Melt polycondensation was performed at ˜245 ° C. to produce a polymer.
This was evaluated in the same manner as in Example 1, and the results are shown in Table 1.

Example 4 A polymer was prepared and evaluated in the same manner as in Example 1 except that the amounts of sodium hypophosphite and monohydrate added were 100 ppm based on the polymer. The results are shown in. Example 5 A polymer was produced in the same manner as in the method of Example 1 except that the addition amount of sodium hypophosphite / monohydrate was 400 ppm with respect to the polymer, and the results were shown in Table 1. showed that.

Comparative Example 1 A polymer was prepared in the same manner as in Example 1 without adding sodium hypophosphite and evaluated, and the results are shown in Table 1. Comparative Example 2 A polymer was produced in the same manner as in Example 2 without adding sodium hypophosphite, and evaluated. The results are shown in Table 1. Comparative Example 3 A polymer was produced in the same manner as in Example 3 without adding sodium hypophosphite and evaluated, and the results are shown in Table 1.

[0017]

[Table 1]

[0018]

According to the present invention, even when the polyester elastomer obtained by polycondensation is melt-held at a temperature of 250 ° C. or higher for a long time, foaming of the molten polymer can be suppressed and deterioration of the polymer is caused. Can be prevented and stable operation can be performed. Furthermore, the content of terminal carboxyl groups of the obtained polymer is low, and a polymer having excellent hydrolysis resistance can be obtained.

─────────────────────────────────────────────────── --- Continuation of the front page (56) References JP-A-52-63294 (JP, A) JP-A-62-199648 (JP, A) JP-A-6-128364 (JP, A) (58) Field (Int.Cl. ⁷ , DB name) C08G 63/00-63/91

Claims (6)

(57) [Claims] 1. An esterification reaction or ester using an aliphatic and / or alicyclic diol having 2 to 12 carbon atoms, polytetramethylene ether glycol having a molecular weight of 500 to 6000, and an aromatic dicarboxylic acid or an alkyl ester thereof as raw materials. When a polyester copolymer in a molten state is produced by polycondensing the oligomer obtained by the exchange reaction and then molded into an appropriate shape, the polyester copolymer in the molten state has 1 to 10 parts.
A method for producing a polyester copolymer, which comprises the presence of 00 ppm of an alkali metal hypophosphite. 2. An aliphatic and / or alicyclic group having 2 to 12 carbon atoms
The group diol is 1,4-butanediol,
The carboxylic acid of claim 1, wherein the carboxylic acid is terephthalic acid.
Method for producing reester copolymer. 3. The amount of alkali metal hypophosphite is 3 to 2.
Polyester according to claim 1 or 2, which is 00 ppm.
A method for producing a copolymer. 4. An esterification reaction using an aliphatic and / or alicyclic diol having 2 to 12 carbon atoms, polytetramethylene ether glycol having a molecular weight of 500 to 6000, and an aromatic dicarboxylic acid or an alkyl ester thereof as raw materials. Or, when producing a polyester copolymer by further polycondensing the oligomer obtained by the transesterification reaction, at least 1 to 100 before the polycondensation is completed.
A method for producing a polyester copolymer, which comprises adding 0 ppm of an alkali metal hypophosphite. 5. An aliphatic and / or alicyclic group having 2 to 12 carbon atoms
The group diol is 1,4-butanediol,
The carboxylic acid according to claim 4, which is terephthalic acid.
Method for producing reester copolymer. 6. The amount of alkali metal hypophosphite is 3 to 2.
Polyester according to claim 4 or 5, which is 00 ppm.
A method for producing a copolymer.