JP2002003589A - Method of producing modified polyester - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a polytrimethylene terephthalate having high thermal shrinkage, flexibility after shrinking and excellent whiteness. SOLUTION: This method comprises the steps of charging polytrimethylene terephthalate and a polyalkylene terephthalate containing 0.5 to 50 mol% of copolymerized isophthalic acid component so that the finally obtainable polyester contains 0.5 to 20 mol% of isophthalic acid component per trimethylene terephthalate unit separately or mixed beforehand into an extruder, and reacting in the extruder to exchange esters.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for producing a modified polyester. More particularly, the present invention relates to a method for producing a modified polytrimethylene terephthalate having high shrinkage, flexibility after shrinkage, good spinnability and improved hue.

[0002]

2. Description of the Related Art Lower alkyl esters of terephthalic acid represented by terephthalic acid or dimethyl terephthalate;
Trimethylene glycol (1,3-propanediol)
Polytrimethylene terephthalate obtained by a polycondensation reaction with polyamide has properties similar to polyamide, such as low elastic modulus (soft feel), excellent elastic recovery, and easy dyeing,
It is an epoch-making polymer that has properties similar to polyethylene terephthalate, such as light resistance, heat setting, dimensional stability, and low water absorption, and is applied to carpets, brushes, tennis gut, etc. JP-A-9-3724, JP-A-8-173244,
JP-A-5-262882).

[0003] Further, by copolymerizing an isophthalic acid component with polytrimethylene terephthalate and melt-spinning the same, for example, a polytrimethylene terephthalate fiber having dyeability lower than that of the polytrimethylene terephthalate fiber can be obtained. This is already known (Japanese Unexamined Patent Publication No.
-12525).

Further, the applicant has found that high shrinkage performance and flexibility after shrinkage can be imparted, and has been proposed in Japanese Patent Application No. 1999-364478.

However, when isophthalic acid is copolymerized with polytrimethylene terephthalate, the rise in melt viscosity is slow, so that the polymerization time is prolonged, and yellowing may occur during the polymerization. When a fiber is made of a polymer having a yellow tint, there is a practical problem such that the coloring becomes poor when dyed in a light color. Polymers that have undergone a long thermal history contain a large amount of oligomers, and the oligomers are susceptible to thermal degradation. Since it cannot be expressed, further improvement has been required.

[0006]

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems of the prior art, and to provide high shrinkage, flexibility after shrinkage, good yarn-making properties and improved hue. An object of the present invention is to provide a method for producing a modified polytrimethylene terephthalate.

[0007]

Means for Solving the Problems In order to solve the above-mentioned problems, the present inventors have studied in detail a method for obtaining isophthalic acid copolymerized polytrimethylene terephthalate by known batch polymerization and continuous polymerization. However, these methods could not sufficiently solve the above problems. Therefore, as a result of further intensive studies, the target copolymerization was achieved when the trimethylene terephthalate polymer and the polyalkylene terephthalate prepolymer obtained by copolymerizing isophthalic acid were melt-kneaded using a vented extruder with high stirring efficiency. The inventors have found the possibility of producing polytrimethylene terephthalate, and have completed the present invention.

That is, an object of the present invention is to provide polytrimethylene terephthalate and isophthalic acid component in an amount of 0.5 to 5%.
The polyalkylene terephthalate prepolymer copolymerized with 0 mol% is separately or preliminarily mixed so that the finally obtained polyester contains 0.5 to 20 mol% of an isophthalic acid component per trimethylene terephthalate unit. After that, the mixture is charged into an extruder equipped with a vent, and transesterification is performed in the extruder.

[0009]

DETAILED DESCRIPTION OF THE INVENTION In the present invention, polytrimethylene terephthalate is substantially a polycondensate of terephthalic acid or a lower ester of terephthalic acid such as dimethyl terephthalate with 1,3-propanediol. Here, "substantially" indicates that polytrimethylene terephthalate may be copolymerized with the polytrimethylene terephthalate as long as it is not more than 5 mol% based on the trimethylene terephthalate unit.

Here, other components which may be copolymerized include 5-sodium sulfoisophthalic acid, tetrabutyl phosphonium salt of sulfoisophthalic acid, phthalic acid, naphthalene-2,6-dicarboxylic acid, oxalic acid, and succinic acid. Acid, adipic acid, sebacic acid, dodecanoic acid, dodecane diacid, cyclohexanedicarboxylic acid, ethylene glycol, butanediol, hexanediol, cyclohexanediol, cyclohexanedimethanol, trimethylene glycol dimer, average molecular weight 400 to 20,000
And the like, and these may be used alone or in combination of two or more.

In the production method of the present invention, the polytrimethylene terephthalate has an intrinsic viscosity of 0.4 to 2.0.
0, preferably 0.5 to 1.5, more preferably 0.6
~ 1.2. Within this range, a fiber having excellent strength and spinnability can be obtained. 0.4 intrinsic viscosity
If it is less than 1, the melt viscosity of the polymer is too low, and the spinning becomes unstable, and the strength of the obtained fiber is too low to be satisfactory. Conversely, when the intrinsic viscosity exceeds 2.0,
Since the melt viscosity is too high, melt fracture or poor spinning occurs during spinning.

In the present invention, the transesterification reaction with the polytrimethylene terephthalate is a polyalkylene terephthalate prepolymer obtained by copolymerizing 0.5 to 50 mol% of isophthalic acid (hereinafter simply referred to as prepolymer). May be done.)

[0013] The copolymerization ratio must be in the range of 0.5 to 50 mol%, and if it is less than 0.5 mol%, the desired effects of the present invention cannot be obtained. %, The polymerization reaction becomes extremely difficult to proceed. From these balances, the copolymerization ratio is preferably 5 to 50.
Mol%, more preferably 10 to 40 mol%. Further, the intrinsic viscosity of the prepolymer is not particularly limited, but is preferably in the range of 0.1 to 1.0 from the viewpoint of increasing the reactivity in a vented extruder.

In the production method of the present invention, any prepolymer can be used as long as it is a polyalkylene terephthalate prepolymer. Among them, polyethylene terephthalate, polytriethylene terephthalate, It is preferable to use a prepolymer consisting of any one of the group consisting of methylene terephthalate and polybutylene terephthalate.

In the production method of the present invention, the prepolymer can be produced by any method. For example, in the case of polyethylene terephthalate, terephthalic acid and ethylene glycol are directly reacted, or a lower polymer such as dimethyl terephthalate is used. A first stage reaction to react with an alkyl ester to form a glycol ester of terephthalic acid and / or a lower polymer thereof;
The reaction product of the step is heated under reduced pressure in the presence of a polymerization catalyst to produce a polycondensation reaction until a desired degree of polymerization is reached. In this case, the copolymer component, isophthalic acid component and additives are added before, after or after the first-stage reaction.
It can be added at any stage, such as before or after the reaction of the stage, and may be added to the system at once or in several portions.

In the production method of the present invention, the polytrimethylene terephthalate and the prepolymer are mixed so that the finally obtained polyester has an isophthalic acid component in the range of 0.5 to 5 mol% per trimethylene terephthalate unit. Are separately or premixed and charged into an extruder equipped with a vent, and subjected to a transesterification reaction in the extruder to obtain isophthalic acid copolymerized polytrimethylene terephthalate. As a method of charging the polytrimethylene terephthalate and the prepolymer to the extruder, both may be chipped and separately supplied to the extruder, or may be mixed in advance and then supplied to the extruder, One may be added while the other is melted in the extruder, or the two may be mixed while being melted.

In supplying these polymers to a vented extruder, a matting agent, a heat stabilizer, a defoaming agent,
A tinting agent, a flame retardant, an antioxidant, an ultraviolet absorber, an infrared absorber, a crystal nucleating agent, a fluorescent whitening agent and the like may be added separately or simultaneously.

In the present invention, the extruder with a vent is
It is an extruder having a vent function that can perform any of inert gas injection, gas discharge, and vacuum suction. Although the extruder function is not particularly limited, it is preferable to use a twin screw type extruder because the kneading performance is high and the reaction can be completed in a short time. Further, it is preferable that the extruder has two or more venting functions so that addition of an inert gas and holding under reduced pressure are possible.

Further, it is preferable that at least a kneading disk and / or a rotor disk is mounted on the extruder with vent used in the production method of the present invention in order to improve the kneading performance. The kneading disc is a kneading screw segment that combines several elliptical discs while shifting them at a fixed phase, and extremely high shearing by passing the polyester mixture through a small clearance with the rotation of the screw. Power can be applied. As a result, the transesterification reaction can be further promoted.

On the other hand, the rotor disk is a screw segment in which a polygonal ridge is twisted at a fixed angle with respect to the rotation axis, and has a feature that the clearance is constant at all positions of the segment. There are forward and reverse feed segments in the direction of the ridge torsion with respect to the screw axis, and by combining these, a high shearing force can be applied uniformly, suppressing the degradation of polyester due to shearing, and suppressing the redistribution reaction. It is possible to proceed.

The kneading segments and / or rotor disks can be appropriately selected depending on the desired redistribution reaction and the target of the physical properties of the polyester such as intrinsic viscosity, and the range is not particularly limited. When the ratio of the segment length (L) to the screw diameter (D) is represented by L / D, the mounting amount of the kneading disk and the rotor disk is preferably in the range of L / D = 1 to 30, more preferably L / D. / D = 2-20. L
When / D is in the above range, a sufficient kneading effect is exhibited, and the redistribution reaction is further promoted.

Further, the temperature in the extruder is set to be 1 point lower than the melting points of the supplied polytrimethylene terephthalate and the prepolymer.
The temperature may be set to 0 to 40 ° C. higher, and preferably 20 to 40 ° C. higher than the melting point.

In the production method of the present invention, at least one of the vent holes in the region where the polytrimethylene terephthalate and the prepolymer are melt-mixed is preferably reduced in pressure using a vacuum pump, a steam ejector or the like. , Usually 10 kPa or less, preferably 5 kPa
The pressure is at most kPa, more preferably at most 1 kPa, and it is preferable to distill off water, alcohol such as methanol, etc. produced with the progress of the polycondensation reaction, or allyl alcohol, acrolein, etc., which are by-products produced in very small amounts.

The transesterification reaction time is 1 to
It is preferably 60 minutes, especially 5 to 30 minutes. Usually, the polycondensation reaction takes about 90 to 250 minutes, but according to the production method of the present invention, the reaction can be completed in a short time as described above. As a result, it is possible to obtain a polymer in which the by-product is sharply reduced and the hue is improved at the same time. Here, the rotation speed of the screw of the extruder with vent is 20
The speed may be set to about 500 rpm, preferably 50 rpm.
３００300 rpm. When a biaxial extruder is used as the vented extruder, the directions of rotation of the two axes may be the same direction or opposite directions, but it is preferable to rotate in the same direction from the viewpoint of suppressing thermal deterioration.

In the production method of the present invention, an inert gas is added when the polytrimethylene terephthalate and / or the prepolymer supplied into the vented extruder is in a molten state. It is more preferable to carry out a transesterification reaction under reduced pressure while keeping both the prepolymer and the molten state.

Here, the method of supplying and adding the inert gas into the vented extruder may be from one place or from a plurality of places, and the inert gas may be nitrogen gas,
Helium gas, argon gas, carbon dioxide gas, and the like can be given. These may be used alone or in combination of two or more. However, from the viewpoint of economy, nitrogen gas is used. Is preferred.

Further, the amount of the inert gas to be added is not particularly limited. However, the amount of the inert gas to be added to the production amount of the modified polyester is converted into the volume of the inert gas at 27 ° C. and atmospheric pressure. , 0.001 to 100 times by volume.

By performing the above operations, the formation of oligomers is suppressed and the removal of existing oligomers is promoted. As a result, the occurrence of thermal degradation is suppressed, and high shrinkage, flexibility after shrinkage, and good A modified polyester having a spinning property and an improved hue can be obtained.

By the above operation, a modified polyester in which 0.5 to 20 mol% of an isophthalic acid component is copolymerized per trimethylene terephthalate unit can be obtained. The copolymerization ratio is 0.5 to 20 mol%. If the copolymerization ratio is less than 0.5 mol%, high shrinkability cannot be obtained. If the copolymerization ratio exceeds 20 mol%, the influence of thermal degradation can be avoided. No, the yellowing resistance and the strength at the time of shrinkage decrease in flexibility. From these balances, preferably 1-2
The content is preferably 0 mol%, more preferably 2 to 15 mol%, and particularly preferably 5 to 13 mol%.

Next, the modified polyester extruded from the vent type extruder may be formed into chips using a chip cutter after passing through a cooling step such as a water cooling bath, or may be directly connected to a spinning machine.

Thus, the modified polyester obtained according to the production method of the present invention has a color L value obtained from a Hunter type color difference meter of 75 or more. Here, the L value is 7
If it is less than 5.0, the molded product which can be used is not obtained because the whiteness is low. The L value is preferably 80 or more, particularly preferably 83 or more.

The modified polyester produced according to the production method of the present invention has a trimethylene terephthalate cyclic dimer content of 1 w
less than t%. When the content exceeds 1 wt%,
That is, when a large amount of oligomer is contained in the modified polyester, the object of the present invention cannot be achieved naturally. The cyclic dimer content is preferably less than 0.95 wt%, particularly preferably 0.90 wt%.
It is less than wt%.

Various additives may be copolymerized or mixed with the polytrimethylene terephthalate and the prepolymer as long as the object of the present invention is not impaired. Examples of such an agent include a matting agent, a heat stabilizer, an antifoaming agent, a tinting agent, a flame retardant, an antioxidant, an ultraviolet absorber, an infrared absorber, a crystal nucleating agent, and a fluorescent brightening agent. Can be

[0034]

EXAMPLES Hereinafter, the present invention will be described more specifically with reference to Examples, but the present invention is not limited thereto.
In addition, each value in an Example was calculated | required according to the following method. (1) Intrinsic viscosity: Determined in orthochlorophenol at 35 ° C. according to a conventional method. (2) Polyester color L value: 100 g of polyester chips are placed in a container, and Minolta Co., Ltd. CHROMOM
The color L value was measured using ETER CR-200. (3) Cyclic dimer content: dissolved in hexafluoroisopropanol / chloroform (1/1 volume ratio)
Waters equipped with a sho TSK-GEL column
The analysis was performed by a high performance liquid chromatograph manufactured by the company. (4) Tensile strength and tensile elongation: determined in accordance with the method described in JIS L1070. (5) Dry heat shrinkage, retention of tensile strength after dry heating, retention of tensile elongation: In a dryer heated to 150 ° C., a 20 cm long test yarn was suspended and held for 10 minutes. The length of the test paper before and after the dry heat treatment was measured to determine the dry heat shrinkage. Further, the tensile strength and tensile elongation of the test yarn before and after the dry heat treatment were measured, and the results were taken as the tensile strength retention and the tensile elongation retention.

Example 1 Dimethyl terephthalate 180
Parts, 1,3-propanediol 120 parts, dimethyl isophthalate 54 parts, titanium tetrabutoxide 0.2 part,
The mixture was charged into a transesterification reactor equipped with a stirrer, a rectification column and a methanol distillation condenser, the temperature was gradually raised from 140 ° C., and the transesterification reaction was started while distilling the produced methanol out of the system. At ℃, the transesterification reaction was terminated. The resulting reaction product was transferred to another vacuum reactor equipped with a stirrer and a diol distillation condenser,
75Pa while increasing the temperature from 210 ° C to 260 ° C
A polymerization reaction was carried out for 30 minutes under reduced pressure to obtain a polytrimethylene terephthalate prepolymer (intrinsic viscosity: 0.3) in which an isophthalic acid component was copolymerized at 30 mol%.

Two weight feeders, two open vents and two vent holes from the chip inlet to the downstream, two kneading disks in L / D conversion, and rotor disks in L / D conversion The trimming terephthalate (intrinsic viscosity: 0.9) prepared in advance is supplied to a co-rotating twin-screw extruder having a weight of 5 while being measured by one weight feeder, and melted at 265 ° C.
The above-mentioned prepolymer was fed into the polytrimethylene terephthalate in a molten state while being metered by the other weight feeder.

Here, the supply ratio is set so that the copolymerization ratio of the finally obtained modified polyester is 10 mol%. During the operation of the extruder, the two kinds of supplied polymers are in a molten state. From the open vent installed in the part
While continuously blowing nitrogen at a volume ratio equivalent to 1: 1 at 27 ° C. and atmospheric pressure with respect to the total weight of the polyester, the nitrogen supplied to the extruder was discharged from the other open vent to the system. After the inside of the extruder was purged with nitrogen, suction was started from a vent hole provided in the extruder, and the pressure in the system became 2.
The pressure was reduced to 0 Pa.

The average residence time of the polymer inside the extruder is 1
For 5 minutes, the rotation speed was 200 rpm. After completion of the transesterification reaction, the obtained modified polyester was extruded into strands, solidified in a water-cooled bath, and then formed into chips by a chip cutter.

The resulting modified polyester chips were copolymerized with 10% by mole of isophthalic acid, had excellent hue, and had an intrinsic viscosity of 0.7. Color L value is 77, trimethylene terephthalate cyclic dimer content is 0.9.
It was 5 wt%.

Further, after the obtained chip was dried at 140 ° C. for 6 hours, the spinning speed was set at 2,000 m / min at 260 ° C.
To obtain an undrawn yarn. Continue with 160
The fiber was drawn at 83 ° C. to obtain a fiber of 83 dtex / 36 filaments. The resulting fiber had a soft feel with a strength of 2.7 cN / dtex, a tensile elongation of 61%, and a dry heat shrinkage of 16%. The strength retention after a dry heat treatment at 150 ° C. for 10 minutes was 95%, and the elongation retention was 140%. In addition, when the spinning was continued for one week continuously, the yarn breakage rate was good at 0 times. The results are shown in Tables 1 and 2.

Example 2 The same operation as in Example 1 was performed, except that polyethylene terephthalate obtained by copolymerizing an isophthalic acid component at 30 mol% was used as the prepolymer. The results are shown in Tables 1 and 2.

Example 3 The same operation as in Example 1 was carried out except that polybutylene terephthalate obtained by copolymerizing an isophthalic acid component at 30 mol% was used as the prepolymer. The results are shown in Tables 1 and 2.

Example 4 The same operation as in Example 1 was carried out except that a vented twin-screw extruder having no kneading disk and rotor disk was used, and nitrogen was not added. Was. The results are shown in Tables 1 and 2.

Comparative Example 1 Dimethyl Terephthalate 188
175 parts of 1,3-propanediol, 8.9 parts of dimethyl 5-sodium sulfoisophthalate, 14 parts of titanium tetrabutoxide, and 3 parts of lithium acetate dihydrate, and the transesterification reaction was terminated at 220 ° C. ,afterwards,
While raising the temperature to 260 ° C.,
A polymerization reaction was carried out for 80 minutes to obtain polytrimethylene terephthalate (intrinsic viscosity 0.7) in which isophthalic acid was copolymerized at 10 mol%. The color L value of the polymer is 6
8. The content of the trimethylene terephthalate cyclic dimer was 1.75% by weight, and slightly yellowish. The results are shown in Tables 1 and 2.

[0045]

[Table 1]

[0046]

[Table 2]

[0047]

According to the production method of the present invention, polytrimethylene terephthalate and a polyalkylene terephthalate prepolymer obtained by copolymerizing a large amount of an isophthalic acid component are reacted in a short time in a vented extruder. It is possible to provide a modified polytrimethylene terephthalate having shrinkability, flexibility after shrinkage, good spinnability and improved hue.

Claims (8)

[Claims] 1. A polyester finally obtained by mixing polytrimethylene terephthalate and a polyalkylene terephthalate prepolymer obtained by copolymerizing an isophthalic acid component in an amount of 0.5 to 50 mol%, wherein the polyester obtained is 0.5 to 20 per trimethylene terephthalate unit. A method for producing a modified polyester, characterized by separately or premixing so as to contain an isophthalic acid component in an amount of mol% and then introducing the mixture into a vented extruder and subjecting it to a transesterification reaction in the extruder. . 2. The polyalkylene terephthalate prepolymer is a prepolymer selected from the group consisting of polyethylene terephthalate, polytrimethylene terephthalate, and polybutylene terephthalate.
The manufacturing method as described. 3. The method according to claim 1, wherein a twin-screw extruder having at least a kneading disk is used as the vented extruder. 4. The method according to claim 1, wherein the vented extruder is a twin-screw extruder having at least a rotor disk. 5. When a polyalkylene terephthalate prepolymer in which a polytrimethylene terephthalate and / or isophthalic acid component is copolymerized in an amount of 0.5 to 50 mol%, which is introduced into a vented extruder, is in a molten state, 2. The production method according to claim 1, wherein an inert gas is introduced into the apparatus, and then transesterification is performed under reduced pressure while both the polytrimethylene terephthalate and the prepolymer are in a molten state. 6. The method according to claim 5, wherein any one of nitrogen gas, helium gas, argon gas, and carbon dioxide gas is used as the inert gas. 7. Obtained by the method of claim 1,
A modified polyester having a color L value of 75 or more. 8. Obtained by the method of claim 1,
A modified polyester having a trimethylene terephthalate cyclic dimer content of less than 1 wt% based on the modified polyester.