JPS5842616A - Production of polyester - Google Patents

Abstract

PURPOSE:To obtain a polyethylene terephthalate polymer suitable for use in high-speed spinning, by producing a polyester by adding terephthalic acid in a specified stage of a polycondensation reaction of dimethyl terephthalate with a glycol. CONSTITUTION:In producing a polyester by transesterifying a dimethyl ester of a terephthalic acid-based dicarboxylic acid and then polycondensing the transesterification product; terephthalic acid in an amount of at least 0.1mol, per 100mol of the diethyl ester of the dicarboxylic acid, is added in a stage from the completion of the transesterification to a point where the number-average polymerization degree of the polycondensation reaction mixture reaches 30. The polyester polymer thus-produced can form a yarn having a high degree of orientation and a low crystallinity without troubles such as yarn break, even when it is spun in a high-speed spinning range of 3,000m/min or higher.

Description

DETAILED DESCRIPTION OF THE INVENTION This book-*Q11 relates to a method for producing polyester. In more detail, the method for producing polyethylene terephthalate polymer is used for high-speed spinning. Polyester, % polyalkylene terephthalate, has many excellent properties as a fiber.

It is used in a wide range of fields such as films and resins.

Among them, polyester, represented by polyethylene terephthalate, is the most widely used in the textile field.

Traditionally, the mainstream method for manufacturing processed polyester fibers, such as polyester filament yarns, has been to perform spinning, elongation, and false twisting in separate processes, but in recent years, it has been possible to obtain With the advent of oriented undrawn yarns, the so-called POY-DTY method, in which stretching and false twisting are performed in one continuous stage, has become mainstream.

This method makes it possible to improve the productivity and shorten the process in the polyester manufacturing process, and is also excellent from the viewpoint of reducing manufacturing costs, and is the mainstream of silk spinning technology.

However, as the spinning speed increases, various problems have arisen. For example, in the far range where the spinning speed is 2500 H7 minutes or more, sometimes 30001 a/min or more, yarn breakage during spinning, yarn breakage during stretching false twisting, etc.
It has been extremely difficult to improve the texture by increasing the spinning speed because problems such as fiber specialization, a decrease in the fuzz strength of the processed yarn, and a decrease in quality such as dyeing spots occur.

Many studies have been made to address these problems.

For example, attempts have been made to optimize spinning conditions such as spinning temperature, cooling air flow rate and temperature, and to improve spinning stubs and spinning rods, but there is a limit to how far problems can be solved. Modification of polynisnal is also being considered, including polyoxyethylene glycols such as diethylene glycol.

Polyfulkylene glycol, copolymerization of compounds with sulfonate groups, or pentaerythritol, trimerin F acid,
Many attempts have been made to copolymerize chain branching agents such as zolopane, and to add metals such as kaolinite and calcium and lithium. However, the improvement method by copolymerization is always accompanied by a decrease in the excellent percent properties of polynisnal, and the addition of metals such as calcium and lithium causes foreign matter in the polymer, resulting in an increase in spinning back pressure and foreign matter around the spinneret. This is not a desirable countermeasure as it also induces undesirable phenomena such as deposition.

After various studies were conducted to find conditions that would prevent such drawbacks and ensure high productivity even in the high-speed spinning range without causing defects, we found that the microstructure of the fibers, such as the degree of orientation and crystallinity of the spun yarn obtained by high-speed spinning, was improved. Factors based on these factors are greatly involved in the quality and quality of the spinning process, and the most advantageous conditions for productivity and quality are when the obtained spun yarn has a high degree of orientation and a low degree of crystallinity. We obtained the knowledge that Based on this knowledge, we are conducting intensive research to supply polyester, which is difficult to obtain spun yarn with island orientation and low crystallinity even in high-speed spinning ranges, particularly at spinning speeds of 3,000 mm/min or higher, using the transesterification method. As a result, they discovered that the objective could be achieved by adding a specific amount of terephthalic acid in a specific reaction zone, leading to the present invention.

That is, the present invention involves transesterifying a bifunctional carboxylic dimethyl ester mainly containing terephthalic acid with at least one type of glycol, and then polycondensing the transesterification reaction product to produce a polyester. From the time when the reaction is substantially completed until the number average degree of polymerization of the condensation reaction mixture reaches 30,
This is a method for producing a polyester, which is characterized in that 01 mole or more of terephtha is added to 100 moles of dimethyl ester of a difunctional carboxylic acid.

The polyester referred to in the present invention is produced by a transesterification method. In general, dimethyl terephthalate and ethylene glyfur, trimethylene glycol, or tetramethylene glycol are transesterified under a transesterification catalyst while distilling methanol out of the system, and for example, extruded methanol is distilled at 90% or more of the theoretical distillation amount. When the transesterification reaction is substantially completed, a stabilizer mainly composed of phosphorus compounds is added, and then the reaction product is subjected to a polycondensation reaction under reduced pressure until a predetermined degree of polymerization is reached. reaction is used.

The first important point in the present invention is that terephthalic acid is If it is added during the process, not only will the transesterification reaction be inhibited, but when the resulting polymer is spun at high speed, the spun yarn with a high degree of orientation and low crystallinity, which is the objective of the present invention, will not be produced. I can't get it. On the other hand, if terephthalic acid is added in the late stage of the polycondensation reaction when the number average degree of polymerization exceeds 30, a polymer with a sufficient degree of polymerization cannot be obtained.

The second requirement is the amount of terephthalic acid added. If the amount added is too small, it will not be possible to obtain a polymer that provides high orientation, low crystallinity, or spun yarn when spun at high speed. It is necessary to set α to 1 mol or more. As the amount of terephthalic acid added increases, the desired effect increases, but when the amount exceeds 10 moles, the effect becomes saturated, so there is no need to add any more. Therefore, the preferable range of addition amount is α5 mol or more, and particularly preferable range is 1 to α5 mol.
It is in the range of 10 moles. Further, as for the method of adding terephthalic acid, it may be directly added in the form of terephthalic acid powder, pellets, or pellets, or it may be added as a slurry dispersion by dissolving in glycol.

In addition, the polyester referred to in the present invention is not only polyalkylene terephthalate, which is the main target, but also a copolymerized polyester using a bifunctional carboxylic acid component other than terephthalic acid and/or a glycol component other than fullkylene glycol, which is the main component. There may be. In addition, the polyester may be mixed with various additives, such as a matting agent (1W), an electric agent (1W), a coloring agent (9), an easy-to-dye agent (9), etc. as necessary, and an ether formation inhibitor such as a carboxylic acid metal salt.

It can also be used in combination with a crystal nucleating agent without any problems.

Even if the polyester polymer obtained in this way is spun at a spinning speed of 250011/min or higher, especially at a high speed range of 3ooo, 7 min or higher, the spun yarn with a high degree of orientation and low crystallinity may be broken. Wjf without any trouble
Since the spinning speed can be increased even further, the spinning speed can be further increased, making it possible to further improve productivity.

In addition, there is little variation in the degree of fiber orientation and crystallinity of the resulting spun yarn, and there are no problems during processing, and the final processed yarn has good quality such as dyeing spots.

The fluctuation was also reduced and the quality was stabilized.

Furthermore, the polymer produced by the method of the present invention can be used not only for fibers but also for films because the degree of orientation, crystallinity, etc. can be easily controlled.

It can also be used as a widely useful material for hollow molded objects such as bottles and molded objects such as resin.

Next, the present invention will be explained in detail with reference to Examples.

Here, I would like to explain the phrases and symbols used in the examples. colL and colb represent the hue of the polymer, which was measured using a Hunter color difference meter. colL
The larger the value of , the higher the whiteness, and the larger the value of col b 1
Indicates a strong yellow tinge.

(c) Number average degree of polymerization Mn is polystyrene f G-2
Measurement was performed by gel permeation columnar imaging (GPC) using 000M8 (manufactured by Toyo Soda).

Δn indicates the degree of fiber orientation.
) Law! It was measured.

(e) The crystallinity of the fiber is the sewage shrinkage rate (
BWS).

However, Lo: fiber length of spun yarn Lf: spun yarn of length Lo in boiling water Fiber after holding for 30 minutes long The larger the BWS value, the lower the crystallinity.

(f) Yarn breakage is indicated by the number of broken yarns out of 100 25 kg yarns.

Example 1 970 parts by weight of dimethyl terephthalate, 64 parts by weight of ethylene glycol, and 31 parts by weight of manganese acetate as a transesterification catalyst were mixed in a stirrer.

The mixture was charged into a reactor equipped with a rectification tower and a methanol distillation condenser, and the transesterification reaction was carried out while heating the internal temperature from 140°C to 230°C and distilling the generated methanol out of the system. 3 hours after starting the transesterification reaction, the internal temperature was 2.
When the temperature reached 30°C, 314 parts by weight of methanol was also distilled out.

At this point, the transesterification reaction was stopped, 0.18 parts by weight of trimethyl phosphate was added as a stabilizer, and the reaction was allowed to proceed for 10 minutes. Then, 0.41 parts by weight of antimony trioxide was added as a polymerization catalyst, and 2.91 parts by weight of titanium dioxide was added as a matting agent. Parts by weight were added and reacted for 20 minutes. Next, the reaction mixture was transferred to a polymerization kettle equipped with a stirrer and a glycol distillation condenser and kept under normal pressure for 10 minutes, and an ethylene glycol slurry (slurry 20% by weight at one time) containing 9.7 parts by weight of terephthalic acid was added to the polymerization kettle. Added A. At this point, the number average polymerization variation of the reaction mixture proboscis was 3. Next, the internal temperature was gradually raised from 230°C to 285°C, and a polycondensation reaction was carried out under a high vacuum of 1 wail. The total polycondensation reaction time is 3
The time was 30 minutes, and the quality of the obtained polymer was
=α64. Softening point 261; 8℃* colL=7j
tS.

e01b=7.0.

This polyester was spun at a spinning speed of ssoom/min.

Polymer melting temperature 290℃, linear velocity of cooling air 15m
A 115 denier/36 filament was spun under the conditions of 1/min (air temperature 26°C, air relative humidity 70°C) and Δn
=a053. A spun yarn with BW8=38- was obtained, and then this spun yarn was stretched and subjected to 1ψ false twisting. There was no yarn breakage during spinning, only one yarn was broken during the drawing and false twisting process, and there was no decrease in product yield due to fuzz, resulting in a good yield of 98 inches. Also, there are no problems with the physical properties of the processed yarn.

Comparison A polymer was obtained in the same manner as in Example 1 except that terephthalic acid was not added, and then high speed spinning and vine stretching false twisting were performed. The total polycondensation reaction time for this polymer was 3 hours and 15 minutes. In addition, the quality of the obtained polymer is [da] =
064+softening point 2610℃, eolL=? 1. s,
601b=7.6, and the physical properties of the spun yarn obtained by high-speed spinning are Δn=0041. BWS=21
%, the degree of orientation was low and the degree of crystallinity was high. There were 5 yarn breaks in the spinning process and 10 yarn breaks in the drawing and false twisting process, and the product yield was low at gs%, which was unnecessary due to the occurrence of fuzz.

Example 2 The amount of terephthalic acid added was 4L9, and the time of addition was set to 30 minutes after the start of pressure reduction in the polycondensation reaction, when the temperature inside the polymerization pot was 270.
A polymer was obtained in the same manner as in Example 141, except that the reaction mixture reached a temperature of 20° C. and the number average degree of polymerization spread was 20, and then high-speed spinning and stretching false twisting were performed. The total polycondensation reaction time for this polymer was 3 hours and 40 minutes. Also,
The quality of the obtained polymer is (η) = o, s 4
, softening point 261.2°C, colL=7a3. eolb=
? , 7, and the physical properties of the spun yarn obtained by high-speed spinning are also Δn=0.0411. BWS=30%, indicating a high degree of orientation and low crystallinity. There were no yarn breakages in the spinning process and no yarn breakages in the stretching and false-twisting process, and there was no occurrence of fluff, and the product yield was good at ss%.

Example 3 Same as Example 1 except that the amount of terephthalic acid added was 49 parts by weight, the pain period was immediately after adding 0 and 18 parts by weight of trimethyl phosphate as a stabilizer, and terephthalic acid was added as a powder. A polymer was obtained in a similar manner and then subjected to high-speed spinning and false twisting. The total polycondensation reaction time for this polymer was 3 hours and 35 minutes. In addition, the quality of the obtained polymer is (η) = OS <, softening point 2622°C
, eolL=710. aolb = 7.4, and the physical properties of the spun yarn obtained by high-speed yarn deposition are Δn = aoso, BWS
=4s- high degree of orientation and low crystallinity. Two yarns were broken during the spinning process, two yarns were broken during the drawing and false twisting process, and the product yield due to fuzz, etc., was also good at 9,896.

Patent applicant Teijin Ltd.

Claims (1)

[Claims] In producing polyester by transesterifying the dimethyl ester of bifunctional carboxylic acid, which is mainly terephthalic acid, and at least one glycol, and then reacting 1 ml of the transesterification reaction product, the transesterification reaction is substantially complete. 1 per 100 moles of dimethyl ester of the difunctional carvone+1 at IR# from the time when the polycondensation reaction temperature is completed until the number average degree of polymerization of the polycondensation reaction mixture reaches 30.
JR manufacturing method for polyester, which involves adding 1 mole or more of terephthalic acid.