JPS58145727A - Production of polyester - Google Patents

Abstract

PURPOSE:To produce a polyester which, when processed by a high-speed spinning, can provide a high-orientation, low-crystallinity product, by adding water during the stage from a point at which the ester interchange reaction is completed to a point at which the polymer reaches a specified polymerization degree. CONSTITUTION:In producing a polyester by ester-interchanging a lower alkyl ester of a dicarboxylic acid based on terephthalic acid (e.g., dimethyl terephthalate or dimethyl terephthalate partially replaced with an alkyl ester of isophthalic acid) with a glycol based on ethylene glycol (e.g., ethylene glycol or ethylene glycol partially replaced with triethylene glycol) and polycondensing the reaction product; water is added during the stage from a point at which the ester interchange reaction is completed to a point at which the polymer reaches a number average polymerization degree of 30. It is possible to provide a polyester suitable for use in high-speed spinning, because it can provide a high- orientation, low-crystallinity product.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing polyester, particularly a method for producing polyester suitable for producing polyef and chill for high-speed spinning.

Polyesters, typified by polyethylene terephthalate, have many excellent properties and are therefore widely used for various purposes, especially for fibers. Polyester fibers are usually melt spun and drawn.

It is used by heat setting.

In recent years, advances in silk spinning technology have made it possible to significantly increase the take-up speed during melt spinning from the conventional 1,000 to 1,500,071/min to more than 2,500 to 4,000,000 m/min (2,500 to 4,000,000 m/min in the past). .Especially the withdrawal speed is 2.
The intermediately oriented undrawn yarn obtained at a speed of 500 to 4000 m/min is usually directly subjected to stretched, twisted and crimped processing, and in recent years, this use has been making remarkable progress and is becoming the mainstream of yarn spinning technology.

Meanwhile, the pickup speed was further increased to 4000. Attempts have also been made to conduct ultrahigh-speed spinning at speeds of 1/min or higher. However, such ultra-high-speed spinning has the disadvantage that yarn breakage occurs frequently during spinning, and furthermore, the strength of the product yarn decreases. Although attempts were made to improve the spinning conditions in order to eliminate this drawback, these measures have limitations and cannot be expected to improve significantly. This tendency is particularly noticeable at speeds of 4,000 m/min or higher, and even though the orientation of the spun yarn has not progressed sufficiently, crystallization occurs to a large extent. This causes the above-mentioned drawbacks.

With the aim of improving these drawbacks, the present inventors have diligently researched a method for producing polyester that exhibits high orientation and low crystallinity during high-speed spinning. It has been shown that adding water until the degree of polymerization reaches 30 has the effect of controlling crystallization during molecular orientation during high-speed spinning.
, arrived at the present invention.

That is, the present invention involves transesterifying lower alkyl esters of difunctional carboxylic acids, mainly terephthalic acid, with glycols, mainly ethylene glycol, and then polycondensing the resulting transesterification product. In addition, in producing polyester, water is added at a stage from when the transesterification reaction is substantially completed until the number average degree of polymerization reaches 30 V'; t).

The lower alkyl esters of difunctional carbonic acids used in the present invention are mainly lower alkyl esters of terephthalic acid, especially dimethyl terephthalate, but some of them may be mixed with other acid components such as infucuric acid, biphenyldicarphone, etc. γ of aliphatic and aromatic dicarboxylic acids such as acids, naphthalene dicarboxylic acid, adipic acid, and sebacic acid.
You can also use lukyl ester.

The glycol component is mainly ethylene glycol, but a part thereof may be copolyester using other glycols such as trimethylene glycol, tetramethylene glycol, and diethylene glycol.

The amount of water used in the present invention is not particularly limited, but in order to achieve a sufficient effect, it is preferably at least 0.05 weight percent relative to the acid component of the polyester. Any method can be used for addition, for example, water may be added alone, it may be added in combination with other additives or modifiers, or it may be added in contact with dead water vapor. The timing of addition is from the time when the transesterification reaction is substantially completed until the number average degree of polymerization reaches 30.If added before the transesterification reaction is practically completed, the transesterification reaction will be delayed. If it is added after the number average degree of polymerization exceeds 30, the polymerization reaction will be delayed and the degree of polymerization will decrease by 1. Because it is possible,
After adding water at the above point, the transesterification reaction product and/or
Alternatively, it is preferable that the low polymer is brought into sufficient contact with water.

The mechanism of suppressing oriented crystallinity by adding water is not necessarily clear; it may be that the hydrolysis caused by water addition or the morphological change of the catalytic metal affect the physical properties of the resulting polyester, especially during high-speed spinning. It is estimated that this has a large influence on the behavior of physical properties.

5- Furthermore, conventionally known additives in the method of the present invention.

Modifiers, such as erasing agents, dyeability improvers, and electrification agents.

The same effect can be achieved by using flame retardants, heat stabilizers, and even crystal nucleating candles in combination.

As described below, the polyester obtained by the method of the present invention can yield polyester fibers with high orientation and low crystallinity in the high-speed spinning range, making it possible to perform high-speed spinning, which was not possible with conventional polyesters. Become.

Next, the present invention will be specifically explained with reference to Examples. In the examples, parts simply mean parts by weight. Here, we will explain the words and symbols used in the examples: (a) [η] is the intrinsic viscosity determined from the viscosity of the polymer measured in orthochlorophni-1-nol solvent at 30°C;
.

(p) colL, cal b represents the hue of the polymer, and was measured using a Hunter type color difference meter.ca
The larger the value of L, the higher the whiteness, and the higher the value of cal b, the stronger the yellowish tinge.
Measurement was performed by gel permeation chromatography (GPC) using 000MB (Toyo Sota Group).

(d) 1＼It indicates the degree of orientation of nut fibers.
It was measured by the rek) method.

(E) The crystallization condition of the fiber is calculated by the following formula: water-saving shrinkage ″$
(BWS).

LO However, Lo: Fiber length of spun yarn Lf: Fiber length after the spun yarn of length LO is kept in water saving mode for 30 minutes BWSO value is larger, indicating lower crystallinity.

Examples 1, 2 and Comparative Example 1 970 parts of dimethyl terephthalate, 6 parts of ethylene glycol
40 parts and 0.3 manganese acetate as transesterification catalyst
1 part (25 mmol 1% to dimethyl terephthal) was charged into a reactor equipped with a stirrer, a rectification column and a methanol distillation condenser, heated from 140°C to 240°C, and methanol produced as a result of the reaction was distilled out of the system. The transesterification reaction was carried out while 3 hours after the start of the reaction, the internal temperature was 230℃
320 parts of methanol was distilled out. 0.18 parts of trimethyl phosphate (25 parts) was added as a stabilizer.
Furthermore, 39.2 parts of water was added in Example 1 (4 weight % to dimethyl terephthalate) and 98 parts (10 weight % to dimethyl terephthalate) in Example 2. After the addition, it was kept under total reflux for 10 minutes, and then 0.44 parts of antimony trioxide (
30 mmoj! 4 parts TeL/FtateL/dimethyl phthalate and 2.91 parts of titanium dioxide as a matting agent, 20
The reaction product was stirred for 23 minutes, and then the resulting reaction product was transferred to a polymerization reactor equipped with a stirrer and a glycol condenser.
Gradually raise the temperature from 0℃ to 285℃ and from normal pressure to 16℃
The polycondensation reaction was carried out while lowering the pressure to a high vacuum in part g. The total polycondensation reaction time was 3 hours and 30 minutes. The physical properties of the obtained oligomer were as shown in Section 1i.

Using this polyester, the melting temperature is 290"C.

Discharge 1138g/min, take-up speed s3o0m/min.

115 denier/36 filaments were wound at a speed of 3600 mm/min and 42 oom/min. The physical properties of the obtained No. 1 filament were as shown in No. 2.

For comparison, the same procedure was carried out without adding water and vinegar (゛), and the results are also listed in Tables 1 and 2 as Comparative Example 1.

--9= Table 1 Table 2 -10- Example 3 The ethyl exchange reaction was carried out in the same manner as in Example 1, except for adding water. After the reaction was carried out for 5 minutes, 98 parts of water was added, the pressure was maintained at 1 for 5 minutes, and then the vacuum reaction was started.The oligomer number average molecular weight at the time of water addition was 3.5.

The thus prepared oligomers were prepared in the same manner as in Example 1.
115 denier/36 filaments were produced at a drawing speed of 300 to 4200 Tn/min.

The properties of the oligomer and the physical properties of the filament are as follows:
It was confirmed that this was a good polymer with suppressed oriented crystallinity.

Claims (1)

[Claims] Polyester is produced by transesterifying the lower fullkyl ester of difunctional carboxylic acid, mainly terephthalate, with glycols, mainly ethylene glycol, and then polycondensing the resulting transesterification product. A method for producing polyester, which comprises adding water at a stage from when the transesterification reaction is substantially completed until the number average degree of polymerization reaches 30.