JPS60250028A - Production of polyester - Google Patents

Abstract

PURPOSE:To obtain a highly polymerized polyester excellent in transparency, hue and thermal properties within a short time, by prepolycondensing a specified terephthalate in the presence of a small amount of a Ge compound or an Sb compound and post-polycondensing the mixture after adding an aromatic sulfonic acid compound. CONSTITUTION:Bis(beta-hydroxyethyl)terephthalte or a composition based on its oligomer is prepolycondensed in the presence of 0.1X10<-4>-1X10<-4>mol, per mol of the acid component constituting the polyester, of a Ge compound and/or an Sb compound to obtain a lowly polymerized polyester of an intrinsic viscosity of 0.2-0.4. After a sulfonic acid compound selected from among compounds of the formula (wherein Ar is an aromatic group, X is OR1, COOR2, or a halogen, m is 1-3, n is 0-3, and R1 and R2 are each H or a lower alkyl) and their acid anhydrides is added in an amount of 1X10<-4>-10X10<-4> equivalent per mol of the acid component constituting the polyester, and the reaction mixture is post-polycondensed.

Description

[Detailed description of the invention] (Industrial application field) The present invention relates to a method for producing polyester, particularly its transparency.

The present invention relates to a method for producing a high degree of polymerization polyester with good color tone and excellent thermal properties in a short time.

(Prior Art) Polyesters, particularly polyethylene terephthalate or polyesters whose main constituent units are ethylene terephthalate units, have been widely used for fibers, films, and other molded products because of their excellent properties.

To produce polyethylene terephthalate.

Usually, bis-(β-hydroxyethyl) terephthalate or its low polymer is formed by transesterifying dimethyl terephthalate and ethylene glycol or by directly esterifying terephthalic acid and ethylene glycol, followed by polycondensation. It is produced by a method of reacting to obtain polyester with desired properties.

However, in the first polycondensation step, especially in the final polycondensation step, two
5 For example, the intrinsic viscosity is 0 because a high temperature of 0°C is required.
．． In order to obtain a polyester of 6 or more, thermal decomposition reactions and other side reactions are almost always involved, which usually causes physical damage to the polyester, such as yellow coloration or an increase in the content of diethylene glycol bonds. properties will be damaged.

Catalysts are generally used in the production of polyester, and aromatic sulfonic acid compounds are known as catalysts that provide polyester with good transparency and one color tone (Japanese Patent Application Laid-Open No. 1983-1999).
- No. 157625).

However, aromatic sulfonic acid compounds have slightly inferior catalytic activity compared to typical polycondensation catalysts such as germanium compounds and antimony compounds. You can now color it.

(Objective of the Invention) An object of the present invention is to provide a method for producing a highly polymerized polyester having good transparency, nine color tones, and excellent thermal properties in a short time.

(Structure of the Invention) As a result of intensive research to achieve the above object, the present inventors conducted initial polycondensation in the presence of a small amount of germanium compound and/or antimony compound, and then formed an aromatic sulfonic acid compound. The present invention was achieved by discovering that it is effective to complete the polycondensation reaction in a short time by adding
The summary is as follows.

When producing a polyester by polycondensing a composition mainly composed of bis(β-hydroxyethyl) terephthalate or a low polymer thereof, first, 0. The first stage polycondensation is carried out in the presence of 1X10' to 1X10-4 moles of a germanium compound and/or an antimony compound to produce a low degree of polymerization polyester having an intrinsic viscosity of 0.2 to 0.4.

Subsequently, a sulfonic acid compound selected from the compound represented by the linear formula or its acid anhydride is added in an amount of IX 10-4 to IOX 10-4 equivalent per mole of the acid component constituting the polyester for late-stage polycondensation. A method for producing polyester characterized by carrying out the following steps.

In the present invention, the intrinsic viscosity (referred to as [η]) of polyester is a value measured at 20° C. in a mixed solvent of equal weights of phenol and tetrachloroethane.

Bis(β-hydroxyethyl) terephthalate or its low polymer (referred to as BIIET) in the present invention is obtained by subjecting terephthalic acid or dimethyl terephthalate and ethylene glycol to an esterification or transesterification reaction by a conventional method.

For example, terephthalic acid and ethylene glycol are
The esterification reaction may be carried out in the presence of T at 230 to 270°C under normal pressure or increased pressure.

In the present invention, first, this Bl(ET) is subjected to early polycondensation in the presence of a small amount of germanium compound and/or antimony compound [η] 0.2-0.4°, preferably 0.25-0. 35 low polymerization degree polyester.

At this time, the amount of germanium compound and/or antimony compound is 0 per mole of acid component constituting the polyester.
．． lX10-4 to lXl0-' mol, preferably 0.2
5 x 10-4 to 0.75 x 10-' mol. If this amount is less than this range, the initial polycondensation time cannot be shortened, and if it is more than this, deterioration of transparency and color tone is unavoidable.

As germanium compounds and antimony compounds, those known as polycondensation catalysts such as germanium dioxide, germanium glycolate, antimony trioxide, antimony acetate, and antimony glycolate can be used, and even if these are added to BHET, B) IET It may be added during the synthesis.

[η] of the low degree of polymerization polyester after the first stage polycondensation is required to be 0.2 to 0.4 as described above. [η]
If it is less than 0.2, the late stage polycondensation must be carried out for a long time, the color tone of the final polyester will deteriorate and the content of diethylene glycol bonds will increase.

In addition, in order to make [η] more than 0.4, it is necessary to increase the amount of germanium compound and/or antimony compound, or increase the time of the initial polycondensation, which may affect the transparency and color tone of the final polyester. deterioration is inevitable.

Following the first polycondensation, a sulfonic acid compound was added to the low polycondensation degree polyester in an amount of 1X10-4 to IOX 10-4 equivalent per mole of the acid component constituting the polyester.

Predetermined degree of polymerization 5 Usually [η] 0.6 or more, preferably 0.
The late stage polycondensation is carried out until it reaches 7 or more. (1 mole of the sulfonic acid compound is m equivalent.) If the amount of the sulfonic acid compound added is less than this range, the late stage polycondensation will take a long time,
Moreover, if it exceeds this range, not only will the polyester be colored yellow, but the content of 1 diethylene glycol bonds will increase.

Specific examples of aromatic sulfonic acid compounds used in the present invention include benzenesulfonic acid, m- or p-benzenedisulfonic acid, 1,3.5-henzentrisulfonic acid, o-, m- or p-sulfonic acid. Benzoic acid, 0-sulfobenzoic anhydride, anisole-〇-sulfonic acid, 1,5-naphthalenedisulfonic acid, 0-, m- or p-chlorobenzenesulfonic acid, O-, m- or p-bromobenzenesulfonic acid , o-, m- or p-fluorobenzenesulfonic acid, 4-chloro-3-methylhenzenesulfonic acid, chlorobenzene-1,4-disulfonic acid, 1-chloronaphthalene-4-sulfonic acid, 2-chloro-4 -Sulfobenzoic acid, 5-sulfosalicylic acid.

Examples include 4-sulfophthalic acid.

The method of the present invention uses not only polyethylene tereclate but also isophthalic acid, p-oxybenzoic acid, 5-sodium sulfoisophthalic acid, adipic acid, propylene glycol, 1,4-cyclohexane dimetatool, and trimellidic acid. .

It can also be applied to the production of polyester containing pentaerythritol or the like as a copolymerization component.

Further, additives such as a catalyst for monomer synthesis, a stabilizer such as a phosphorus compound, and a color improver such as a cobalt compound or a fluorescent agent may be present together. (In some cases, a matte polyester may be obtained by adding a degreasing agent such as titanium dioxide.) (Example) The present invention will be explained in more detail with reference to Examples below. The examples are not limited in any way.

In the examples, characteristic values were measured as follows.

(a) Content of diethylene glycol bonds After alkaline hydrolysis of polyester, ethylene glycol and diethylene glycol were determined by gas chromatography, and the mol% of diethylene glycol based on the total glycol ([
It is expressed as lEG%).

(b) Color The polyester obtained 8 times was molded into granules and heated at 150°C ± 2°C.
After crystallization for 1 hour, the a and b values were determined using a color difference meter. L value is lightness (the larger the value, the brighter).

The a value is red - the hue of the edge thread (+ means reddish, - means greenish).

The b value represents the hue of yellow-blue light (+ means yellowish, - means bluish). As for the color spacing of polymers, the L value is large.

The closer the a value is to O, and unless it becomes extremely small, the b
The smaller the value, the better.

(C) Transparency (haze) Polyester granules were prepared under reduced pressure (5 mmHg) at a temperature of 15
After drying at 0℃ for 5 hours, thickness 4.5mm x length 10cm
Injection molded into a plate of m x medium 6 cm (extrusion temperature 28
5°C), and check the transparency of the plate using H manufactured by Suga Test Instruments Co., Ltd.
Evaluation was made using a GM-2D type haze meter (air: haze O%).

Examples 1 to 11 and Comparative Examples 1 to 10 A slurry of terephthalic acid and ethylene glycol (ethylene glycol/terephthalic acid molar ratio 1.2) was continuously supplied to an esterification reactor in which BIIET was present,
The esterification reaction was carried out at a temperature of 250'C and under normal pressure for a residence time of 5 hours and 15 minutes, with an esterification reaction rate of 95%, [η)
0.10. A direct esterification product with a DEG% of 1.1 was prepared continuously.

This product was placed in a stainless steel test polymerization apparatus.

At 275° C., the pressure was gradually reduced from normal pressure to 0.1 mmt1 g, and germanium dioxide (abbreviated as Ge in Table 1) was used as the germanium compound, and antimony trioxide (abbreviated as sb in Table 1) was added as the antimony compound. 1. Adding the amount shown in 1. Performing early polycondensation for the time shown in Table 1. 2. Preparing a low degree of polymerization polyester with [η] shown in Table 1.
As a sulfonic acid compound, 0-sulfobenzoic anhydride (
In Table 1, it is abbreviated as O5B. ) or 5-sulfosalicylic acid (abbreviated as SS in Table 1) in the amounts shown in Table 1 at a temperature of 275°C.

The late stage polycondensation was carried out under a reduced pressure of 0.1 mm1 for the time shown in Table 1, and the results shown in Table 1 were obtained.

According to Table 1, [η] of the polyester after the first stage polycondensation is 0.
．． If it is less than 20, the DEG% of the final polyester will be high and the color tone will be poor (b value will be high).

When the amount of catalyst added is increased so that [η] exceeds 0.4, the color tone of the final polyester becomes poor and the transparency of the plate obtained by molding becomes poor.

If the amount of catalyst added in the first polycondensation is large, the [
Even if the initial polycondensation time is shortened to keep η] in the range of 0.2 to 0.4, one color tone and transparency cannot be improved.

If the amount of the 5-sulfonic acid compound added is less than 1Xl0-4 mol per mol of the acid component constituting the polyester, not only will the [η] of the final polyester not reach the target, but the color tone and transparency will deteriorate significantly, and on the other hand, , l0XI
If it exceeds O-4, the color tone of the final polyester will deteriorate,
DEG% also increases.

(Effect of the invention) According to the method of the present invention, the single polycondensation time is shortened.

Excellent transparency and color tone are maintained, and the by-product of diethylene glycol bonds is suppressed, making it possible to industrially advantageously produce a high-quality polyester with good thermal properties.

Patent applicant Nippon Ester Co., Ltd. Agent Yuzo Kodama

Claims (1)

[Claims] (11 When producing a polyester by polycondensing a composition mainly composed of bis(β-hydroxyethyl) terephthalate or a low polymer thereof, first, 0 per mole of the acid component constituting the polyester. The first stage polycondensation is carried out in the presence of .1X10' to 1X10-4 moles of germanium compound and/or antimony compound to obtain a low degree of polymerization polyester having an intrinsic viscosity of 0.2 to 0.4, and then the polyester is expressed by the linear formula. A sulfonic acid compound selected from compounds or acid anhydrides thereof per mole of the acid component constituting the polyester.
A method for producing polyester, which comprises adding 10-4 to 10XIO-4 equivalents to carry out late-stage polycondensation. Formula (X)n-Ar-(SO3H)mAr: aromatic group X: OR+, COOR2 or halogen m: 1-
3. rzo~3 However, R1 and Rt are hydrogen or a lower alkyl group,
n=0 indicates that there is no substituent other than the sulfonic acid group, and when n≧2, 5X does not need to be the same substituent.