JPH06263850A - Production of polyester - Google Patents

Abstract

PURPOSE:To obtain a polyester improved in wet heat resistance, flowability, and molding cycle by polymerizing naphthalenedicarboxylic acid with tetramethylene glycol in the presence of a specific oligomer having a low degree of polymn. under specified conditions. CONSTITUTION:The melt polycondensation of an acid component contg. at least 80mol% naphthalenedicarboxylic acid with a glycol component contg. at least 80mol% tetramethylene glycol is started at 240 deg.C or higher. When the intrinsic viscosity of the resulting polymer reaches 0.5 or higher, a glycol ester of oxalic acid of the formula (wherein R1 is alkylene excluding butylene; and (n) is 4 or lower) and/or an oligomer having a low degree of polymn. formed by using oxalic acid as the acid component is added to the reactional in such an amt. of the ester and/or oligomer as to be 0.6-10.0mol% of the acid component (provided when the (n) of the oxalic ester is 2 or higher, one repeating unit is regarded as 1mol). Then, the polymn. is continued until the intrinsic viscosity reaches a specified value.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polybutylene naphthalene dicarboxylate (hereinafter referred to as polybutylene naphthalate) having excellent wet heat resistance and good molding performance such as fluidity of molten resin at molding and molding cycle property. Or it may be abbreviated as PBN).

[0002]

2. Description of the Related Art Polyesters containing tetramethylene glycol as a main glycol component, for example,
Polybutylene terephthalate (hereinafter abbreviated as PBT) and PBN-based polymers have excellent chemical and mechanical properties,
It is widely used as a material for fibers, films, plastics, etc., and due to its particularly excellent crystallinity, it has become widely used in electronic and electrical parts, automobile interior and exterior parts, and molded products centered on injection molding these days. It was Recently, the quality and shape required for these molded products have become more complex, thinner, and more compact than ever, reflecting technological or social needs such as higher functionality, lighter weight, and resource saving. ing. Therefore, it is an essential requirement that polyester with high molding performance during molding as a molding material, that is, that it has good fluidity characteristics in the mold during molding, and that it has excellent molding cycle properties in terms of productivity. Has been done.

Further, in automotive applications, there is also a high demand for a polyester having high moist heat resistance that can be used for a long period of time under severe conditions of high temperature and high humidity, and at present, a high performance polyester material satisfying these characteristics is strongly desired. It has been demanded. The former improvement of molding fluidity has been proposed in various ways, and examples thereof include addition of ordinary plasticizers, addition of low-molecular weight substances, and reduction of viscosity of the polymer itself by reduction of molecular weight. In the case of a polymer having a higher crystallization rate, controlling the crystallinity can be mentioned from the viewpoint of the effect of suppressing the solidification of the polymer due to the crystallization in the mold. Regarding the latter method of improving the resistance to moist heat, it has been proposed to reduce the concentration of carboxyl groups by using compounds such as ethylene carbonate, diphenyl carbonate, diphenyl terephthalate, epoxy compounds, bisoxazoline and polyoxalate. However, most of the modifiers for improving the moist heat resistance generally tend to increase the viscosity and deteriorate the fluidity,
When a wide variety of additives are included in order to satisfy the contradictory improvement of properties, a new problem of deterioration of physical properties occurs.
As a means for improving the fluidity and wet heat resistance of polyester, a method using a specific glycol ester of oxalic acid in PBT (JP-A-4-31721) has already been proposed. However, while the fluidity is improved, the effect of suppressing the crystallinity is bothered, and in the conventional molding cycle, there is a problem that mechanical properties are deteriorated due to insufficient crystallization, and also in terms of wet heat resistance. It cannot always be said that the recent severe requirement level is satisfied.

On the other hand, in this respect, PBN is generally superior to PBT in mechanical properties, resistance to moist heat, resistance to chemicals, and the like, and has a very high crystallization rate. It can be inferred that it is a highly performant material. It is predicted that the viscosity of the polymer is high and the crystallization speed is too fast, so that the solidification of the polymer in the mold at the time of molding is fast and the molding characteristics are too difficult.

[0005]

Means for Solving the Problems As a result of intensive studies to improve such points, the present inventors have found that when a specific oxalic acid glycol ester is used based on PBN, there is a problem with PBT. It was found that there is no decrease in mechanical properties in the same molding cycle, the fluidity in the mold can be significantly improved, and at the same time, the carboxyl concentration decreases. Therefore, the inventors have found a polyester material having good molding performance and very excellent resistance to moist heat, and arrived at the present invention.

That is, according to the present invention, when a polyester having naphthalene dicarboxylic acid as a main acid component and glycol having a carbon number of 4 as a main glycol component is produced by melt polymerization, the intrinsic viscosity is 0.5 in the polymerization process of the polyester.
In the subsequent stage after reaching the low temperature, a low-polymerization degree oxalic acid oligomer having a glycol ester of oxalic acid represented by the formula (I) and / or oxalic acid as a main acid component in the reaction system.

[0007]

[Chemical 2]

(Wherein R ₁ is an alkylene group having a carbon number other than 4 and n is an integer of 4 or less) based on the total acid component constituting the polyester in an amount of 0.6 to 10 mol% [however,
When the oxalic acid ester is n = 1 or more, the repeating unit is 1 mol.], And the polymerization reaction is further carried out.

In a PBN polyester having naphthalenedicarboxylic acid as a main acid component and glycol having 4 carbon atoms as a main glycol component, the term "main" means 80.
It means at least mol% and includes those obtained by copolymerizing 20 mol% or less of the third component. The copolymerization amount is particularly preferably 10 mol% or less. Further, as the copolymerizable third component, an aromatic dicarboxylic acid other than naphthalenedicarboxylic acid, for example, terephthalic acid, terephthalic acid, diphenyldicarboxylic acid, diphenoxyethanedicarboxylic acid, diphenyletherdicarboxylic acid, diphenylketonedicarboxylic acid, sodium sulfoisophthalic acid. Acid, dibromoterephthalic acid, etc .; alicyclic dicarboxylic acid, such as hexahydroterephthalic acid, decalin dicarboxylic acid, etc .; aliphatic dicarboxylic acid,
For example, malonic acid, succinic acid, adipic acid, etc .; aliphatic diols other than butanediol, such as ethylene glycol, trimethylene glycol, neopentyl glycol, diethylene glycol, etc .; aromatic dihydroxy compounds, such as bisphenol A [2,2'-bis ( 4-hydroxyphenyl) propane], bisphenol S, tetrabromobisphenol A, bishydroxyethoxybisphenol A, etc .; aliphatic oxycarboxylic acids such as glycolic acid, 3-oxypropionic acid, etc .: alicyclic oxycarboxylic acids such as asiatic acid , Quinobaic acid, etc .; aromatic oxycarboxylic acids such as P-hydroxybenzoic acid,
P-hydroxyethoxybenzoic acid, mandelic acid, tetrolactic acid and the like can be mentioned. These third components may be used alone or in combination of two or more. Further, the copolyester is a polyfunctional compound having a valence of 3 or more, for example, within a range in which the polymer can be substantially linear,
A small amount of glycerin, trimethylolpropane, pentaerythritol, trimellitic acid, trimesic acid, pyromellitic acid, tricarbamic acid, etc. may be copolymerized, and monofunctional compounds such as O-benzoylbenzoic acid and naphthoic acid may be used. Or the like, or a monofunctional compound such as O-benzoylbenzoic acid or naphthoic acid may be bonded.

Such PBN can be produced by a usual melt polymerization method. For example, transesterification reaction between dimethyl naphthalate and 1,4-butanediol is carried out, or naphthalene dicarboxylic acid and 1,4-butanediol are directly esterified to give substantially bis (β-hydroxybutyl). ) Naphthalate or a low polymer thereof is formed, and polycondensed under reduced pressure of 240 ° C. or higher to produce it.

In the present invention, a glycol ester of oxalic acid represented by the following formula (I) and / or an oxalic acid-based oligomer is added during the polycondensation reaction of PBN. Use here

[0012]

[Chemical 3]

(However, R ₁ in the formula is an alkylene group other than 4 carbon atoms, and n is an integer of 4 or less.) A glycol ester of oxalic acid and / or an oxalic acid ester oligomer is crystallized from PBN. In order to suppress the rate, the glycol component must be an ester compound of 1,4-butanediol having 4 carbon atoms, which is the main feature of improving fluidity in the mold, which is the solidification rate of the polymer in the mold. In addition, the addition timing of the glycol ester of oxalic acid or the oxalic acid ester oligomer is at least after the stage when the intrinsic viscosity of PBN reaches at least 0.5. It is preferable to add it at the stage when it becomes 7 or more.When adding before the intrinsic viscosity is less than 0.5, the intrinsic viscosity of PBN when added is very high. As a result, the polycondensation time after that becomes longer, and the concentration of the carboxyl group of the obtained PBT is again increased, which makes it impossible to achieve the object of the present invention. Is in the range of 0.6 to 10 mol%,
In particular, 1.0 to 7.0 mol% is preferable [however, when the oxalic acid ester is n = 1 or more, the repeating unit thereof is 1 mol].
The effect of suppressing the crystallization rate is small, there is no substantial improvement in fluidity in the mold, and PB with a sufficiently low carboxyl group concentration.
I can't get N. On the other hand, if the amount added is too large, significant foaming will occur, causing trouble in the reaction process, and the subsequent polycondensation reaction will take a long time, resulting in a re-increase in the carboxyl group concentration of PBN, resulting in hydrolysis resistance. Not only worsens, but also the adverse effect on heat resistance due to the lowering of the melting point reaches a level that cannot be ignored.

When producing the PBN, ordinary catalysts, stabilizers, various additives and the like may be added if necessary.

The PBN obtained by the present invention can be used as a mechanical structural material or an automobile part.

[0016]

EXAMPLES The present invention will be described in detail below with reference to examples. “Parts” in the synthesis examples and examples represent parts by weight, and the characteristic values were measured by the following methods. Intrinsic viscosity: [η] It was calculated from the solution viscosity measured at 35 ° C using a solvent having a composition of phenol / tetrachloroethane of 3/2. Carboxyl group concentration: (equivalent / 10 ⁶ g) A. CONIX method (Makromol, chem., 26, 226 (195
8)). Melting point and crystallinity: 1090B type D manufactured by Du Pont
Using SC, sample 10 mg at 300 at 20 ° C / min
Raise the temperature to ℃ and hold it for 2 minutes, then 10 ℃ / min
The temperature was lowered at, and the melting point peak temperature (Tm) and the high temperature crystallization peak temperature (Tcd) were measured.

[0017]

[Synthesis Example 1] 0.03 part of manganese acetate was dissolved in 3.4 parts of ethylene glycol, 4.0 parts of diethyl oxalate was added, and the mixture was heated to 160 ° C to distill off the ethyl alcohol produced as a result of the transesterification reaction. It was The pressure was gradually reduced under an N ₂ atmosphere, and the reaction was performed by heating under the conditions of 20 mmHg for about 10 minutes. The average degree of polymerization of the oxalic acid ethylene ester polymer obtained at this time was 1.4.

[0018]

[Synthesis Example 2] The same procedure as in Synthesis Example 1 was repeated except that manganese acetate was changed to 0.20 part of titanium tetrabutoxide and reacted at 10 mmHg for 30 minutes. The average degree of polymerization of the oxalic acid ethylene ester polymer obtained at this time was 3.5.
Met.

[0019]

[Synthesis Example 3] 0.02 part of titanium tetrabutoxide was dissolved in 6.3 parts of hexamethylene glycol, 4.0 parts of diethyl oxalate was added, and the mixture was heated to 180 ° C to carry out a transesterification reaction to produce ethyl alcohol. Distill and gradually reduce the pressure under N ₂ atmosphere to 20 mmHg
The mixture was heated and reacted for 30 minutes under heat. The average degree of polymerization of the oxalic acid hexamethylene ester polymer obtained at this time was 1.
It was 3.

[0020]

[Synthesis Example 4] 0.04 parts of titanium tetraoxide is dissolved in 4.9 parts of 1,4-butanediol, 4.0 parts of diethyl oxalate is added, and the mixture is heated to 160 ° C. to produce a transesterification reaction. Ethyl alcohol was distilled off. After that, gradually reduce the pressure under N ₂ atmosphere to 20 m.
The mixture was heated and reacted under mHg for about 10 minutes. The average degree of polymerization of the oxalic acid butylene ester polymer obtained at this time is
It was 1.6.

[0021]

Example 1 2.6-Dimethylnaphthalate 35.0
Part, 1,4-butanediol 20.7 parts, tetra-n-
Butyl titanate 0.008 parts and Irganox 10
760.040 parts were charged into a transesterification reaction tank, and 2
A transesterification reaction (abbreviated as EI reaction) was carried out at 10 ° C. for 180 minutes, and methanol distilled during the reaction was distilled out of the reaction system. The amount of methanol distilled at the end of the reaction was 9.
It was 5 parts. After completion of the EI reaction, the reaction solution was transferred to a polycondensation tank for polycondensation reaction (abbreviated as PN), and the reaction temperature was raised from 210 ° C to 260 ° C over 35 minutes while gradually increasing the degree of vacuum. . While maintaining this temperature, the degree of vacuum was maintained at 0.3 mmHg, and the PN reaction was performed for 170 minutes. Here, the reaction system was returned to normal pressure using N ₂ . The intrinsic viscosity of the obtained polymer was 0.60. Here, 1.12 parts of the oxalic acid ethylene ester polymer of Synthesis Example 1 (PB
After adding 5.0 mol% to all the acid components constituting N, the pressure was gradually returned to a reduced pressure, and the polycondensation reaction was continued again under a reduced pressure of 0.3 mmHg until a desired intrinsic viscosity was reached (35 Minutes). Then, it was discharged from a slit-shaped die and cooled to obtain a 4 × 4 × 2 mm cylindrical chip. The obtained polymer has an intrinsic viscosity of 0.77 and a carboxyl group concentration of 12
The equivalent weight was 10 ⁶ g.

[0022]

[Comparative Example 1] The same procedure as in Example 1 was carried out except that an oxalic acid-based polyester was not added, and the reaction was carried out to a desired intrinsic viscosity in a normal reaction without returning N ₂ to normal pressure during the polymerization reaction. .

[0023]

Examples 2 to 5 and Comparative Examples 2 to 5 The procedure of Example 1 was repeated, except that the type of oxalic acid type polyester polymer, the addition timing and the addition amount were changed as shown in Table 1.

[0024]

Comparative Example 6 35.0 parts of dimethyl terephthalate 1,
2-butanediol 20.7 parts, tetra-n-butyl titanate 0.008 parts and Irganox 1076
0.040 parts was charged in an EI tank, EI reaction was carried out at 170 ° C., and then a polymerization reaction was carried out at 245 ° C. for 170 minutes, and one end was returned to normal pressure with N ₂ . The intrinsic viscosity of the polymer obtained here was 0.69. At this point, 1.40 parts (5.0 mol% with respect to the total acid components constituting PBT) of the oxalic acid ethylene ester polymer of Synthesis Example 1 was added, and the polymerization reaction was repeated until the desired intrinsic viscosity was reached. went. The polymer obtained had an intrinsic viscosity of 0.92 and a carboxyl group concentration of 12 equivalents / 10 ⁶ g.

[0025]

Comparative Example 7 Without adding oxalic acid ethylene ester,
The same procedure as in Comparative Example 6 was carried out, except that N ₂ was not returned to normal pressure during the polymerization reaction and the reaction was carried out to a desired intrinsic viscosity by a normal reaction.

Table 1 shows the quality and crystallinity of the PBN and PBT polymers obtained (corresponding to the Tcd of DSC).
Summarized in.

[0027]

[Table 1]

Furthermore, in order to evaluate the fluidity, mechanical properties and wet heat resistance of these polymers, the chips obtained in Examples 1 to 5 and Comparative Examples 1 to 7 were pre-dried at 130 ° C. for 7 hours to obtain an antioxidant ( Trgano × 1010 / Mar
k PEP24P) 0.10 / 0.05 wt% and a release agent (WAX-E) 0.5 wt% were uniformly compounded, and then molding was performed using an injection molding machine and conditions according to the evaluation purpose.

Evaluation of fluidity (flow length) Molding machine: FANUC Auto Shot MATE Cylinder temperature: PBN270 ° C, PBT250 ° C Mold temperature: 80 ° C Cooling time: 10 seconds Holding pressure: 100 kg / cm ² Injection speed: 130 mm / S Injection pressure: 400 kg / cm ² Molded product shape: Width 10 mm x thickness 0.5 mm Flat plate The longer the flow length of the obtained molded product is, the better the fluidity is ・ Mechanical property evaluation Molding machine: 5 ounce injection molding machine Cylinder Temperature: PBN290 ° C, PBT260 ° C Cooling time: 20 seconds Injection pressure: 700 kg / cm ² Molded product shape: Tensile test piece The obtained test piece and its hot water-degraded product, tensile strength, and tensile elongation are in accordance with ASTM-D638. Measured.

Evaluation of Moisture and Heat Resistance The tensile elongation retention rate of the test piece before and after the hot water deterioration treatment at 100 ° C. for 200 hours was evaluated. Table 2 shows these evaluation results.
It was shown to.

[0031]

[Table 2]

As is clear from Tables 1 and 2, when a polyalkylene oxalate polymer synthesized with a glycol having a carbon number other than 4 was added at a specific addition amount above a certain intrinsic viscosity, P
It is possible to obtain a BN having a low temperature crystallization rate and a low carboxyl group concentration, that is, the effect of delaying the cooling and solidifying rate in the mold is improved, and the fluidity is improved, and the low carboxylic group concentration effect is effective for moist heat resistance. Was found to have improved. Further, in the conventional PBT system, when the present technique was used, mechanical property (tensile strength) deterioration after molding was observed [Comparative Examples 6 and 7], but in the case of PBN, almost no such tendency was observed.

Since PBN has a much higher crystallization rate than PBT, it is presumed that even if the crystallinity is suppressed to some extent, the effect on the crystallinity of the obtained molded product is small. It

As described above, the present invention has higher moist heat resistance than the conventional PBT system, and is excellent in molding performance such that mechanical characteristics are not deteriorated without changing molding conditions. found.

[0035]

INDUSTRIAL APPLICABILITY According to the present invention, a PBN having improved molding performance and excellent moisture and heat resistance can be produced to form a thinner and more complicated molded product, and the conventional P
It can be applied to applications such as automobile parts and machine structural parts that are used under high temperature and high humidity, which cannot be handled by BT and PBN.

Claims (1)

[Claims] 1. When melt-polymerizing a polymer containing naphthalenedicarboxylic acid as a main acid component and tetramethylene glycol as a main glycol component, after the intrinsic viscosity of the polymer reaches 0.5 or more, the following formula (I) [Chemical 1] [However, in the formula, R ₁ represents an alkylene group other than a butylene group, and n represents an integer of 4 or less. ] The low-polymerization degree oligomer having a glycol ester of oxalic acid and / or oxalic acid as an acid component represented by the above is 0.6 to 10.0 mol% (provided that the oxalic acid is When the ester has n = 1 or more, the repeating unit thereof is regarded as 1 mol), and the polymerization reaction is continuously continued to reach a predetermined intrinsic viscosity.