JPH06116378A - Production of polyester - Google Patents

Abstract

PURPOSE:To obtain a polyester excellent in hue and heat resistance, etc., hardly having acetaldehyde content and causing no whitening in forming bottles by adding specific two kinds of compounds to a reactional system in producing polyethylene naphthalene dicaroxylate. CONSTITUTION:In producing polyester by reacting a dicarboxylic acid component consisting essentially of a lower alkyl ester of naphthalene-2,6-dicarboxylic acid with a glycol component consisting essentially of ethylene glycol, (A) a metallic compound (preferably NaOH, etc.) selected from an alkali metal compound and an alkaline earth metal compound and (B) an ammonium compound (preferably hydroxytetramethyl ammonium) of the formula (R1 to R4 are H, alkyl, etc.; A is anion residue) is added to the reactional system at arbitrary stage until the reaction is finished. Furthermore, the compound A is preferably used in an amount of 4X10<-4> to 9X10<-4> based on 1mol dicarboxylic acid component and the compound B is preferably used in an amount of 0.2X10<-4> to 1X10<-4>mol based on 1mol dicarboxylic acid component.

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, more specifically, a polyester having a good hue, excellent heat resistance and transparency, a small amount of acetaldehyde produced, and substantially no whitening during bottle molding. It relates to a manufacturing method.

[0002]

2. Description of the Related Art Polyesters, particularly polyethylene terephthalate (hereinafter sometimes abbreviated as "PET"), are excellent in mechanical properties and chemical properties, and thus fibers, films,
Widely used in industrial resins, bottles, cups, trays, etc.

However, in recent years, demands for quality have become more severe in various applications. Among them, polyester containers, especially biaxially stretched blow containers, are desired to have improved heat resistance and gas barrier properties from the viewpoints of sterilization and storability of the filler, and PET containers may be insufficient. Moreover, in terms of the appearance of the container, improvement in hue is also required.

On the other hand, polyethylene naphthalene dicarboxylate (hereinafter sometimes abbreviated as "PEN") is also known for its excellent characteristics, and is superior to PET in terms of heat resistance and gas barrier property. Therefore, many applications to films and containers have been reported.

For example, Japanese Patent Application Laid-Open No. 52-45466 proposes a method of using PEN as a material for a hollow container having excellent gas barrier properties, heat resistance and transparency.

On the other hand, a method for producing a polyester using a salt of an alkali metal and / or an alkaline earth metal as a catalyst is known from the viewpoint of improving the hue of the polyester and preventing the generation of scale. For example, US Pat.
No. 22, Japanese Patent Publication No. 48-32195, Japanese Patent Publication No. 49-13
No. 234 and Japanese Examined Patent Publication No. 2-8616. In particular, Japanese Patent Publication No. 2-8616 mentioned above proposes a method for producing a haze-free polyester, and describes that the produced polyester is suitable for hollow containers.

[0007]

Therefore, when PEN is produced by using the above-mentioned metal compound, it is possible to obtain a material which is originally superior in heat resistance and gas barrier property to PET with improved hue and transparency. It seems that the polyester will be suitable for hollow containers with strict quality requirements.

[0008] However, according to the study of the present inventors, the PEN thus obtained has a large amount of acetaldehyde or bleaching due to crystallization when a biaxially stretched blow container is molded. We have found that there are problems to be solved.

Thus, an object of the present invention is to obtain a polyethylene naphthalene dicarboxylate which is originally excellent in heat resistance and transparency as a product having a good hue, a low acetaldehyde content, and almost no whitening during bottle molding. To provide a method.

[0010]

[Means for Solving the Problems] The inventors of the present invention have conducted extensive studies to achieve the above object. As a result, by coexisting a specific ammonium compound together with the above metal compound during the production of PEN, whitening occurs during bottle molding. The present inventors have found that PEN with almost no aldehyde content and a low aldehyde content is obtained, and completed the present invention.

That is, according to the present inventor, naphthalene-
A method for producing a polyester by reacting a dicarboxylic acid component mainly composed of a lower alkyl ester of 2,6-dicarboxylic acid with a glycol component mainly composed of ethylene glycol, at any stage until the reaction is completed. ,
(A) at least one metal compound selected from the group consisting of alkali metal compounds and alkaline earth metal compounds, and (b) the following general formula (1)

[0012]

[Chemical 2]

(Wherein R ₁ , R ₂ , R ₃ and R ₄ are each independently a hydrogen atom, an alkyl group, a cycloalkyl group,
An aryl group, an aralkyl group, or a substituted derivative thereof is shown. However, R ₃ and R ₄ may combine with each other to form a divalent group. Further, there is provided a method for producing a polyester, which comprises adding an ammonium compound represented by A).

[0014]

[Structure] The structure of the present invention will be described in detail below, but it will become apparent from the more preferable embodiments of the present invention and the advantages based thereon.

The dicarboxylic acid component of the present invention mainly comprises a lower alkyl ester of naphthalene-2,6-dicarboxylic acid (hereinafter sometimes abbreviated as "2,6-DAN"). Examples of the lower alkyl ester include dimethyl ester, diethyl ester, dipropyl ester and dibutyl ester.

As the dicarboxylic acid component of the present invention, an ester of a dicarboxylic acid other than the above 2,6-DAN can be contained, but the amount thereof is 30 mol% or less, preferably 20 mol% of the total amount of the dicarboxylic acid component. It is the following.

Dicarboxylic acids other than 2,6-DAN include naphthalene-2,7-dicarboxylic acid, terephthalic acid, isophthalic acid, diphenyldicarboxylic acid, diphenoxyethanedicarboxylic acid, diphenyletherdicarboxylic acid, diphenylketone dicarboxylic acid, sodium salt. Aromatic dicarboxylic acids such as sulfoisophthalic acid and dibromoterephthalic acid; Alicyclic dicarboxylic acids such as hexahydroterephthalic acid and decalindicarboxylic acid; Aliphatic dicarboxylic acids such as malonic acid, succinic acid and adipic acid .

The glycol component of the present invention is mainly composed of ethylene glycol, but may contain other glycol in an amount of 30 mol% or less, preferably 20 mol% or less, based on the total glycol component.

As glycol components other than ethylene glycol, aliphatic diols such as hexamethylene glycol, neopentyl glycol and diethylene glycol;
Aromatic dihydroxy compounds such as bisphenol A
Aromatic dihydroxy compounds such as [2,2-bis (4-hydroxyphenyl) propane], bisphenol S, tetrabromobisphenol A, and bishydroxyethoxybisphenol A can be used.

Further, in the production method of the present invention, in addition to the dicarboxylic acid component and the glycol component, the total amount of 1 mol of the dicarboxylic acid component and the glycol component is 0.
It is also possible to use a small amount of an oxycarboxylic acid component of not more than 05 mol, preferably not more than 0.01 mol.

Examples of the oxycarboxylic acid component include aliphatic oxycarboxylic acids such as glycolic acid and 3-oxypropionic acid; alicyclic oxycarboxylic acids such as asiatic acid and quinobaic acid; aromatic oxycarboxylic acids such as Mandell. Acid, atrolactic acid, etc. can be mentioned.

In any case, in the polyester obtained by the production method of the present invention, the sum of the amount of structural units derived from 2,6-DAN and the amount of structural units derived from ethylene glycol is 90 mol% or more, particularly Is preferably 95 mol% or more.

In the present invention, the dicarboxylic acid component and the glycol component are reacted with each other. As the method, a method known per se used for producing polyethylene terephthalate can be adopted. For example naphthalene-2,6-
It can be produced by performing a transesterification reaction using a lower alkyl ester of dicarboxylic acid and ethylene glycol, and further polycondensing the obtained reaction product. Further, it is preferable to use a transesterification catalyst, a polymerization catalyst, a stabilizer and the like when producing these polyesters. As these catalysts and stabilizers, those known as catalysts and stabilizers for polyester, especially polyethylene terephthalate, can be used.

As the transesterification catalyst, calcium,
Metal compounds such as magnesium, lithium, zinc, cobalt and manganese can be used. Examples of the form of these compounds include oxides, hydroxides, halides, inorganic acid salts, organic acid salts and the like.

Typical examples of the polymerization catalyst include antimony trioxide, germanium oxide and alkoxides such as titanium tetrabutoxide.

The stabilizer is typically phosphoric acid,
Mention may be made of phosphoric acid, hypophosphorous acid, polyphosphoric acid and esters of phosphoric acids such as mono- or dimethyl phosphoric acid.

Specific examples of the alkali metal compound and the alkaline earth metal compound in the present invention include organic carboxylates such as acetates, oxalates, benzoates, phthalates and stearates; inorganic hydrochloric acid, For example sulphate,
Examples thereof include carbonates; halides such as chlorides; chelate compounds such as ethylenediaminetetraacetic acid complex salts; alcoholates such as methylates, ethylates, glycolates; other hydroxides and oxides.

In particular, organic carboxylic acid salts, halides, chelate compounds and alcoholates which are soluble in ethylene glycol are preferable, and organic carboxylic acid salts are particularly preferable.

Further, preferable metals include magnesium, sodium, potassium and the like.

Specific examples of the most preferable metal compound include magnesium acetate, sodium acetate, potassium acetate, calcium acetate, sodium hydroxide and potassium hydroxide.

These metal compounds may be used alone or in combination of two or more.

The ammonium compound in the present invention is represented by the above general formula (1). In formula (1), R ₁ ~
Each R ₄ independently represents a hydrogen atom, an alkyl group, a cycloalkyl group, an aryl group, an aralkyl group or a substituted derivative thereof. However, R ₃ and R ₄ may combine with each other to form a divalent group. A represents an anion residue.

The alkyl group is preferably one having 1 to 6 carbon atoms, specifically, a methyl group, an ethyl group, a butyl group,
A hexyl group etc. can be mentioned.

The cycloalkyl group has 5 to 6 carbon atoms.
And a cyclopentyl group, a cyclohexyl group and the like can be specifically exemplified.

The aryl group preferably has 6 to 8 carbon atoms, and specific examples thereof include a phenyl group, a tolyl group and a xylyl group.

The aralkyl group preferably has 7 to 9 carbon atoms, and specific examples thereof include a benzyl group and a cumyl group.

R ₃ and R ₄ may combine with each other to form a divalent group. In this case, the nitrogen atom of formula (1) is included to form a ring. The divalent group is preferably an alkylene group having 4 to 6 carbon atoms, specifically, a tetramethylene group, a pentamethylene group,
A hexamethylene group and the like can be specifically exemplified.

A is an anion residue, and examples thereof include a halogen, a hydroxyl group and an alkoxyl group.

Specific examples of preferable ammonium compounds include quaternary ammonium salts such as hydroxytetramethylammonium, hydroxytetraethylammonium, hydroxytetrabutylammonium and tetraethylammonium chloride; tertiary ammonium salts.
Examples thereof include hydroxytrimethylammonium; secondary ammonium salts such as hydroxydimethylammonium; primary ammonium salts such as hydroxymethylammonium; ammonium salts such as hydroxyammonium and ammonium chloride. The above ammonium compounds may be used alone or in combination of two or more.

Of these, use of hydroxytetramethylammonium or hydroxytetraethylammonium is preferred.

The most important feature of the present invention is that the metal compound (a) and the ammonium compound (b) are added at any stage where the dicarboxylic acid component and the glycol component are reacted. That is, it may be added at the initial stage of the transesterification reaction or at the latter stage of the polycondensation reaction.

The thermal decomposition of the polymer is suppressed by adding the metal compound (a) and the ammonium compound (b). Further, the ammonium compound (b) is presumed to have a function of finely dispersing the residual particles in the polymer derived from the transesterification catalyst, which is considered to promote whitening of the blow container due to crystallization. As a result, the hue of the obtained polyester is improved, the content of acetaldehyde in the molded product is reduced, and whitening due to crystallization is almost suppressed when molding the biaxially stretched blow container.

The metal compound (a) is a dicarboxylic acid component 1
2 × 10 per mole^-Four~ 10 x 10 ^-FourTo add a mole
Preferably 4 × 10^-Four~ 9 × 10^-FourMol is preferred
Yes. The ammonium compound (b) is a dicarboxylic acid component 1
0.02 x 10 per mole^-Four~ 5 x 10^-FourMolar addition
Is preferable, and especially 0.2 × 10^-Four~ 1 x 10^{- Four}
Molar is preferred.

Metal compound (a) and ammonium compound
When adding substance (b), is it dispersed in glycol?
Alternatively, mix with glycol and start from a small pot to the reaction tank.
To N ₂Add by pressurization, then the pot with glycol
Such as by washing and adding a washing solution to the reaction tank.
It can be done easily. Also, add the entire amount at once.
It is not necessary to add them, and they can be added separately.

The polyester of the present invention thus produced can be used not only for biaxially stretched blow containers but also for films, injection molded products, fibers and the like.

At this time, if necessary, additives such as a colorant, an antioxidant, an ultraviolet absorber, an antistatic agent and a flame retardant can be added.

[0047]

EXAMPLES The present invention will be described in detail below with reference to examples. In addition, "part" in an Example means a weight part. or,
Each property of the obtained polyester was measured by the following methods.

(1) Intrinsic viscosity [η] Phenol / tetrachloroethane (60/40 weight ratio)
It was calculated from the solution viscosity measured at 35 ° C. using a mixed solvent. (2) Col b (b value of hunter) C on Color Machine CM-1500 type color machine
ol b was measured. (3) Acetaldehyde It was measured by Hitachi Gas Chromatography-163 type. (4) Haze Measured with an integrating sphere type light transmittance measuring device. (5) Bottle whitening evaluation The obtained polymer pellets were used as a molding machine M-100A manufactured by Meiki Seisakusho Co., Ltd. to obtain a bottle forming preform, which was further molded with a OR-01 molding machine manufactured by CORPOPLAST to form a biaxially stretched bottle. Got Cut the body of this bottle and use a haze meter NDH-20D manufactured by Nippon Denshoku Co., Ltd.
The haze of the test piece was measured by a method according to STM D1003.

Example 1 Dimethyl-2,6-naphthalenedicarboxylate 12
170 parts to 170 to 235 are charged with 2 parts, 62 parts of ethylene glycol, and 0.086 parts of magnesium acetate (8 × 10 ⁻⁴ mol per 1 mol of the above-mentioned dimethyl-2,6-naphthalene dicarboxylate) in the transesterification reaction tank. The transesterification reaction was carried out at ° C. When the distillate was no longer produced, 0.016 parts of germanium oxide and 0.0015 parts of hydroxytetraethylammonium (0.2 × 10 4 parts with respect to 1 mol of the above-mentioned dimethyl-2,6-naphthalenedicarboxylate) were used.
^-4 mol) and 0.043 part of orthophosphoric acid were added and transferred to a polymerization reaction tank. The reaction was carried out at 260 to 270 ° C. for about 10 minutes under normal pressure, and then at 290 ° C. under high vacuum (high vacuum of several mmHg or higher) for 100 minutes. The intrinsic viscosity [η] of the obtained polymer was 0.65 dl / g.

The polymer thus obtained was extracted into a large amount of running water by a conventional method to obtain strand type chips. This chip was further heat-treated in a polymerization reaction tank at 220 ° C. under high vacuum (high vacuum of several mmHg or more) for about 6 hours. The chips thus obtained had an intrinsic viscosity [η] of 0.75 dl / g and acetaldehyde of 1.0 p
It was pm. The Col b was -1.2. This chip was further injection-molded at 290 ° C for 60 seconds, and vertical 11c
A molded plate having m, a width of 11 cm, and a thickness of 0.2 cm was prepared, and the acetaldehyde and haze of this molded plate were measured and found to be 6.8 ppm and 1.6%. Further, the haze of the molded bottle piece was measured and found to be 2.1%.

Examples 2, 3 and Comparative Example 1 Example 1 was repeated except that the amount of hydroxytetraethylammonium added was changed. The results are summarized in Table 1.

[0052]

[Table 1]

[0053]

The method for producing a polyester of the present invention provides a polyester having a good hue, excellent heat resistance and transparency, a low content of acetaldehyde, and substantially no whitening during bottle molding. The polyester produced by the method of the present invention is mainly used for containers and packaging materials,
It can be advantageously used as a fiber, a film, or a resin molded product.

Claims (3)

[Claims] 1. A method for producing a polyester by reacting a dicarboxylic acid component mainly composed of a lower alkyl ester of naphthalene-2,6-dicarboxylic acid with a glycol component mainly composed of ethylene glycol, wherein the reaction is completed. At any stage until (a) at least one metal compound selected from the group consisting of alkali metal compounds and alkaline earth metal compounds and (b) the following general formula (1) (However, R ₁ , R ₂ , R ₃ and R ₄ are each independently a hydrogen atom, an alkyl group, a cycloalkyl group, an aryl group,
An aralkyl group or a substituted derivative thereof is shown. However, R
₃ and R ₄ may combine with each other to form a divalent group. In addition, A is an ammonium compound represented by an anion residue), and a method for producing a polyester. 2. A dicarboxylic acid component 1 containing a metal compound (a).
The production method according to claim 1, wherein the addition is performed in a ratio of 2 × 10 ⁻⁴ to 10 × 10 ⁻⁴ mol with respect to the mol. 3. The production method according to claim 1, wherein the ammonium compound (b) is added in a ratio of 0.02 × 10 ^{−4 to} 5 × 10 ⁻⁴ mol with respect to 1 mol of the dicarboxylic acid component.