JP3017296B2 - Polyester production method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a polyester by a melt polymerization method and a solid state polymerization method, and more particularly, to an excellent method comprising naphthalenedicarboxylic acid as a main acid component and tetramethylene glycol as a main glycol component. The present invention relates to a method for producing a polyester having a color tone and wet heat resistance.

[0002]

2. Description of the Related Art Conventionally, polyesters containing tetramethylene glycol as a main glycol component, for example, polytetramethylene terephthalate (hereinafter sometimes abbreviated as "PBT"), polytetramethylene-2,6-naphthalenedicarboxylate (hereinafter referred to as "PBT"). PBN ")
And the like are known to be useful as various molded article materials having various excellent mechanical properties and excellent moldability.

[0003] As a method for producing such a polyester,
Taking polytetramethylene-2,6-naphthalenedicarboxylate as an example, transesterification of dimethyl-2,6-naphthalenedicarboxylate with tetramethylene glycol, or 2,6-naphthalenedicarboxylic acid and tetramethylene There is known a method of subjecting a glycol to an esterification reaction and then polycondensing the resulting tetramethylene glycol diester of 2,6-naphthalenedicarboxylic acid and / or a low polymer thereof, a so-called transesterification method or a direct polymerization method.

For example, Japanese Patent Publication No. 57-45773 discloses that when a polytetramethylene-2,6-naphthalenedicarboxylate is produced by a direct polymerization method, the molar ratio of a glycol component to an acid component is 1.7 to 5; And a method in which the esterification reaction is carried out at a temperature in the range of 180 ° C. to 230 ° C. and the polycondensation reaction is carried out in the range of the polymer melting point to 275 ° C.
In the production of polytetramethylene-2,6-naphthalenedicarboxylate by a transesterification method, a titanium compound and an antimony compound or a titanium compound and a magnesium compound are used as catalysts in JP 671 and JP-B-56-39340. A method of doing so has been proposed.

On the other hand, the use environment of electric / electronic parts such as connectors using engineering plastics such as PBT and polyamide, and automotive parts materials has recently become increasingly severe such as high temperature and high humidity. Therefore, in order to satisfy those uses, it is becoming essential to use PBT or the like having a highly improved resistance to moist heat. As a method for improving wet heat resistance, it is known that reduction of the concentration of terminal carboxyl groups of a polymer is effective in PBT. As a method for reducing the concentration, an alkali metal compound is added at any stage of melt polymerization of the polymer. (JP-A-57-147516) or solid-phase polymerization (JP-A-49-16794, JP-B-59-5).
No. 2895) is known.

However, in such an improvement, the strength of the wet heat resistance is improved, but the elongation is hardly improved, and is significantly reduced after the hot water deterioration test. Therefore, even in such a highly improved PBT, the physical properties are not satisfied, and it may be insufficient depending on the use.

[0007]

SUMMARY OF THE INVENTION An object of the present invention is to provide a method for producing a polyester having excellent wet heat resistance and good color tone.

[0008]

DISCLOSURE OF THE INVENTION The present invention provides a method for producing a polyester by polycondensing a dicarboxylic acid component mainly comprising naphthalenedicarboxylic acid and / or an ester-forming derivative thereof with a glycol component mainly comprising tetramethylene glycol. In doing so, an alkaline compound is added at any stage before the completion of the melt polymerization reaction, and then the polyester obtained by the melt polymerization reaction is solid-phased at a temperature lower than the melting point of the polyester under a high vacuum or in an inert gas stream. This is a method for producing a polyester characterized by polymerizing.

The "dicarboxylic acid component" used in the present invention refers to naphthalenedicarboxylic acid, for example, 2,6-
Naphthalenedicarboxylic acid, 2,7-naphthalenedicarboxylic acid and / or an ester-forming derivative thereof are mainly used, and a part thereof (30 mol% based on the total acid component) is used.
Below, preferably 20 mol% or less) with other dicarboxylic acids such as terephthalic acid, isophthalic acid, 4,4'-diphenyldicarboxylic acid, dipheninoxyethane-4,
4'-dicarboxylic acid, diphenylsulfone-4,4'-
Aromatic dicarboxylic acids such as dicarboxylic acid and diphenyl ether-4,4'-dicarboxylic acid; and aliphatic dicarboxylic acids such as sebacic acid and adipic acid may be substituted. Further, as the ester-forming derivative of the acid component,
Examples thereof include lower alkyl esters, phenyl esters, and acid anhydrides.

The "glycol component" mainly includes tetramethylene glycol, and a part thereof (30 mol% or less, preferably 2 mol% or less based on the total glycol component).
0 mol% or less) may be replaced with another glycol such as ethylene glycol, neopentyl glycol, trimethylene glycol, hexamethylene glycol, decamethylene glycol, cyclohexane dimethylol and the like.

The melt polymerization of the polyester of the present invention can be carried out by a known method. That is, an acid component and a glycol component can be converted to an arbitrary catalyst, for example, a titanium compound, a tin compound,
After the esterification or transesterification in the presence of the magnesium compound, a polycondensation reaction is performed under high vacuum.

In the present invention, the term "alkaline compound" refers to a hydroxide, an inorganic acid salt or an organic acid salt, for example, an acetate or a carbonate, of Group Ia (alkali metal) or Group IIa (alkaline earth metal) of the periodic table. Alternatively, there are hydrates, complex salts, ammonium salts and the like of these, and these can be used in combination of at least one kind and, if desired, several kinds. Specific examples of the alkaline compound include lithium hydroxide, sodium hydroxide, potassium hydroxide, rubidium hydroxide, cesium hydroxide, francium hydroxide, beryllium hydroxide, magnesium hydroxide, strontium hydroxide, barium hydroxide, and lithium acetate. , Sodium acetate, potassium acetate, magnesium acetate, calcium acetate, lithium carbonate, sodium carbonate, potassium carbonate, lithium benzoate, sodium benzoate, potassium benzoate and the like.

Also, an ammonium compound represented by the following general formula (I) (formula 1) and a salt thereof

Embedded image (Wherein R ¹ , R ² , R ³ and R ⁴ are a hydrogen atom, an alkyl group, an aryl group, a cycloalkyl group, an arylalkyl group, and even if R ¹ , R ² , R ³ and R ⁴ are the same, And the following general formula (II)
The amine compound represented by the formula (2) can also be the alkaline compound of the present invention.

Embedded image (In the formula, R ⁵ , R ⁶ and R ⁷ are a hydrogen atom, an alkyl group, an aryl group, a cycloalkyl group and an arylalkyl group, and R ⁵ , R ⁶ and R ⁷ may be the same or different. Here, examples of the salt of the ammonium compound represented by the general formula (I) include salts of organic acids and halogens.

Specific examples of such ammonium compounds, salts thereof and amine compounds include methylamine, ethylamine, propylamine, isopropylamine, butylamine, amylamine, hexylamine, heptylamine, octylamine, nonylamine, decylamine, undecylamine, Dodecylamine, tridecylamine,
Tetradecylamine, pentadecylamine, cetylamine, allylamine, cyclopropylamine, cyclobutylamine, cyclopentylamine, cyclohexylamine, m-toluidine, p-toluidine, o-toluidine, benzylamine, α-naphthylamine, β-naphthylamine, ammonia, Dimethylamine, diethylamine, diisopropylamine, dibutylamine, diamylamine, diallylamine, dibenzylamine, diphenylamine, trimethylamine, triethylamine, tripropylamine, tributylamine, triamylamine, triallylamine, tribenzylamine, triphenylamine, tetraethylammonium terephthalate , Tetraethylammonium hydroxide, tetraethylammonium hydroxide Chloride and ammonia water. These may be used alone or in combination of two or more. Of these, sodium compounds and potassium compounds are particularly preferred.

The use amount of these alkaline compounds is not particularly limited. However, if the amount is too small, the effect of improving the wet heat resistance is small even if the solid phase polymerization is carried out later, and if the amount is too large, the obtained polyester is undesirably colored. Therefore, the usual use amount is preferably in the range of 3 to 100 mmol% with respect to the acid component. When an alkaline compound is used in such a preferable range, the amount of terminal carboxyl groups is reduced in the same manner as disclosed in the case of PBT, and as a result, the moist heat resistance is improved. In the present invention, the alkaline compound is added at an arbitrary stage before the completion of the melt polymerization reaction. There is no effect if it is added to the solid phase polymerization stage. Preferably, it is added during the period from the start of the esterification or transesterification reaction to the initial reaction of the polymerization.

The intrinsic viscosity [η] of the polyester (prepolymer) after melt polymerization to be subjected to solid-state polymerization is not particularly limited, but is usually 0.4 to 1.0 dl / g. Further, the solid-phase polymerization method is not particularly limited, except that the solid-phase polymerization method is carried out under a high vacuum, for example, 5 mmHg or less, preferably 1 mmHg or less, or under a flow of an inert gas such as nitrogen gas at a temperature equal to or lower than the melting point of the polyester. The temperature ranges from (melting point -15 ° C) to (melting point-
30 ° C.). If the solid-state polymerization temperature is too high, fusion occurs between the solid-state polymerization device walls or the polymer pellets, which is not preferable, and the reaction rate is reduced with time and coloring is liable to occur. On the other hand, if the solid-state polymerization temperature is too low, the reaction rate at the beginning of the reaction is slow and inefficient. In addition, regarding the solid-state polymerization apparatus for performing solid-state polymerization, since the polyester has a rapid crystallization rate, crystallization has already progressed to some extent when pelletizing for supply of solid-state polymerization after completion of melt polymerization. And there are few restrictions on the device. Accordingly, the present invention can be carried out in any of the well-known batch-type or continuous-type solid-state polymerization apparatuses such as a tumbler type or a packed column type.

However, the solid-phase polymerization is preferably carried out under such conditions that the final carboxyl group concentration of the polymer becomes 30 equivalents / 10 ⁶ g or less. If the terminal carboxyl group concentration exceeds 30 equivalents / 10 ⁶ g, the effect of improving the wet heat resistance is insufficient. The decrease in the terminal carboxyl group concentration in the solid-state polymerization step is 5 equivalents / 10 ⁶ g or more,
Preferably it is 10 equivalents / 10 ⁶ g or more.

[0018]

The present invention will be described below in detail with reference to examples. In the examples, “parts” means “parts by weight”. The physical properties and the like were as follows. Intrinsic viscosity [η] It was determined from the solution viscosity measured at 35 ° C in a phenol / tetrachloroethane (weight ratio: 3/2) mixed solvent. Color L, a, b measured with Minolta Colorimeter CR-100
The value was determined. Here, the L value represents brightness, and L = 100
Is white and L = 0 is black. The a-value indicates a reddish to greenish color. A larger value on the + side with respect to 0 indicates a reddish color, and a larger value on the − side indicates a greenish color. Further, the b value indicates yellowish to bluish, with a larger value on the + side with respect to 0 indicating a more yellowish color, and a larger value on the − side indicates a more bluish color. Terminal carboxyl group [COOH] Method of A. Conix [Macromol. Chem.] 2
6, 226 (1958)]. The unit is the number of carboxyl group equivalents per 10 ⁶ g of the polymer. Wet heat resistance (boiling water deterioration test) A tensile test piece was treated in boiling water (100 ° C) for 200 hours, and the strength and elongation of the test piece were measured to evaluate the strength retention rate. Here, the tensile strength and elongation are ASTM D-638.
It measured by the method according to.

Examples 1-4, Comparative Examples 1-3 Dimethyl-2,6-naphthalenedicarboxylate 9
7.6 parts, 43.3 parts of tetramethylene glycol, 0.027 parts of tetrabutyl titanate and a predetermined amount of the alkaline compound listed in Table 1-1 were put into a transesterification tank, and the transesterification reaction rate was determined (from the methanol distillation amount). At the time when the theoretical amount becomes 70% of the theoretical amount, the reaction is performed while raising the internal temperature to 190 ° C., and then the obtained reaction product is transferred to a polycondensation reaction tank, and the pressure is raised to 265 ° C. while reducing the pressure to a high vacuum. Warm,
The reaction was terminated when the reaction time under a high vacuum of 0.5 mmHg reached 60 minutes. The obtained PBN polymer having a melting point of 245 ° C. was formed into chips. This chip (prepolymer) is placed in a crystallization tank of a complete mixing tank type equipped with a stirrer, and heat-treated at 150 ° C. for 3 hours in an N ₂ gas atmosphere to be crystallized. Solid phase polymerization was performed under vacuum under the conditions shown in Table 1-1 (product polymer). The quality of the obtained polymer is shown in Tables 1-1 to 1-3.

Comparative Example 4 100 parts of dimethyl terephthalate, 73 parts of tetramethylene glycol, 0.74 part of tetrabutyl titanate and 20 mmol% of potassium acetate (relative to dimethyl terephthalate) were placed in a reactor and transesterification was carried out at 170 ° C. . When 85% of the theoretical amount of methanol was distilled off, the temperature was raised to 200 ° C., and after 10 minutes, the system was weakly vacuumed (〜3
The internal temperature was raised to 240 ° C. while pulling to 0 mmHg, and after suction for 30 minutes, the reaction was carried out at 242 ° C. by pulling the system to 1 mmHg or less. The obtained polybutylene terephthalate having a melting point of 225 ° C. was formed into chips. This chip (prepolymer) was put into a crystallization tank of a complete mixing tank type with a stirrer, and
After crystallization under the same conditions as described above, the mixture was supplied to a packed tower tank to form 0.1 g.
Solid phase polymerization was performed under the conditions shown in Table 1-1 under a high vacuum of 5 mmHg (product polymer). Table 1 shows the quality of the obtained polymer.
1 to Table 1-3.

[0021]

Table 1-1 | −−−− | −−−−−−−−−−−− | −−−−−− | −−−−−− ||||||| Phase polymerization conditions | | |-------------------------| | | Name | Amount | [η] | COOH | Temperature | Time | (M mol%) | (dl / g) | | (° C) | (hr) | |--------------------- − | −−− | −−− | │Example 1│Potassium acetate│20│0.8│32│215│12││Example 2│Sodium acetate│20│0.8│35│215│12.5││Example 3 | Sodium hydroxide | 20 | 0.8 | 38 | 215 | 13 || Example 4 | Ammonia | 90 | 0.8 | 40 | 215 | 13.5 || −−−− | −−−−−−−−−−−− − | −−− | −− | −−− | −−− | | Comparative Example 1 |-|-|| 1.0 | 62 | Not performed | | Comparative example 2 |-|-| 0.8 | 51 | 215 | 12 | | Comparative example 3 | Potassium acetate | 20 | 1.0 | 40 | Not performed | | Comparative example 4 | Potassium acetate | │ 30 │ 190 │ 12 │ │ −−−− | −−−−−−−− | −−−− | −−− | −− | −−− |

[Table 1-2] |---------------------------------------------------------------------| Properties after boiling water deterioration | | |-----------------------------| | | [η] | COOH | Tensile strength | | (Dl / g) | | (kg / cm ² ) | (%) | (kg / cm ² ) | (%) | | −−−− | −−−−−− − | −−−− | −−−− | −−−− | −−−− | | Example 1 | 1.0 | 19 | 660 | 140 | 658 | 116 || Example 2 | 1.0 | 20 | 658 | 138 | 645 | 110 | | Example 3 | 1.0 | 25 | 640 | 138 | 620 | 108 | | Example 4 | 1.0 | 28 | 640 | 136 | 600 | 97 | |---------| −−− | −−−− | −−−− | −−−− | −−−− | | Comparative Example 1 | 1.0 | 62 | 610 | 131 | 528 | 52 || Comparison Example 2 | 1.0 | 38 | 626 | 135 | 571 | 75 || Comparative Example 3 | 1.0 | 40 | 619 | 128 | 537 | 71 || Comparative Example 4 | 1.0 | 20 | 530 | 170 | 519 | 60 || −−−− | −−− | −−− | −−−− | −−−− | −−−− | −−−− |

[Table 1-3] |-------------------------------------| −−−−−− | −−−−−−− | −−− | −−− | −−− | | | | Strength Retention (%) | Elongation Retention (%) | L | a | b | | −−−− | −−−−−−− | −−−−−−− | −−− | −−− | −−− | | Example 1 | 99.7 | 82.9 | 83.0 | -2.1 | -2.0 || Example 2 | 98.0 | 79.7 | 82.5 | -2.5 | -1.8 || Example 3 | 96.9 | 78.3 | 82.8 | -2.6 | -1.7 || Example 4 | 93.8 | 71.3 | 80.5 | -1.5 |- 0.9 | |----------------------------------| Comparative Example 1 | 86.6 | 39.7 | 73.5 | 0 | 1.0 || Comparative Example 2 | 91.3 | 55.6 | 80.1 | -1.5 | -1.2 || Comparative Example 3 | 86.8 | 55.5 | 76.3 | -0.3 | +0.7 || Comparative Example 4 | 98.0 | 35.3 | 81.0 | -1.4 | -1.4 | |-----------------------------|

[0022]

According to the present invention, it is possible to obtain a polyester polymer containing naphthalenedicarboxylic acid and tetramethylene glycol as main components, which is more excellent in moist heat resistance and color tone than highly improved PBT.

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) C08G 63/189/63 / 80,63 / 83

Claims (1)

(57) [Claims] 1. A polyester is produced by polycondensing a dicarboxylic acid component mainly comprising naphthalenedicarboxylic acid and / or an ester-forming derivative thereof and a glycol component mainly comprising tetramethylene glycol.
Adding an alkaline compound at any stage before the completion of the melt polymerization reaction, and then subjecting the polyester obtained by the melt polymerization reaction to solid phase polymerization at a temperature lower than the melting point of the polyester under a high vacuum or in an inert gas stream. A method for producing a polyester, characterized in that: