JPH0539349A - Production of copolyester - Google Patents

Abstract

PURPOSE:To produce a copolyester which has high water absorption and retention properties and maintains these properties for a long term by reacting an arom. dicarboxylic acid component with a glycol component in the presence of a metal salt of a dicarboxyarenesulfonic acid and a specific polyoxyalkylene compd. CONSTITUTION:At least one arom. dicarboxylic acid (e.g. terephthalic acid) is made to react with at least one diol compd. (e.g. ethylene glycol) in the presence of a metal salt of a dicarboxyarenesulfonic acid or its ester-forming deriv. (e.g. 5-sodium sulfoisophthalic acid) in an esterification reactor at about 230 deg.C under about 2.5kg/cm<2> pressure. The reactional product, a polyoxyalkylene compd. of formula I or II (wherein R1 and R3 are each a 1-18C hydrocarbon group; R2 and R4 are each an ethylene or propylene unit; and (n1) and (n2) are each an integer of 10-100), and other additives such as an antioxidant are put into a polycondensation reactor, where the product and the compd. are polycondensed for producing the objective copolymer at about 280 deg.C under a reduced pressure until the intrinsic viscosity reaches 0.5dl/g.

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 copolyester having excellent wettability. More specifically, due to its high surface water wettability, when it is made into fibers, it exhibits high water absorption and water retention in the form of an aggregate such as a non-woven fabric, and is also suitable for treatments such as washing. Nevertheless, it relates to a method for producing a fiber-forming copolyester capable of maintaining high water absorption and water retention over a long period of time.

[0002]

2. Description of the Related Art Polyester fibers typified by polyethylene terephthalate fibers have many excellent properties such as easiness of care and are widely used for various purposes. Therefore, the water absorbency is remarkably inferior to that of natural fibers such as cotton, and its use in fields requiring water absorbency is greatly limited.

Conventionally, attempts have been made to impart hydrophilicity or water absorbency to polyester fibers in order to solve this problem, but most of them have been made by devising the fiber shape or post-processing. For example, in non-woven fabric applications where high water absorption and water retention are required, the coating of a hydrophilic agent on the fiber surface and polyoxyalkylene glycol-
It has been practiced to knead a hydrophilizing agent such as a metal salt derivative of sulfonic acid or sulfonic acid into polyester during spinning. Some of them are effective, but there is a risk that these hydrophilizing agents will fall off or elute during the addition step and during use.
Long-term effects cannot be expected. In addition, since the safety of the hydrophilizing agent that has fallen off or eluted is unknown to the human body, the practical use is considerably limited.

On the other hand, as a method for modifying the polymer itself for the purpose of obtaining a polyester having hydrophilicity, it is known to copolymerize polyoxyethylene glycol, but the effect is relatively small. It remains a thing. As another method for improving the defects of polyester by modifying the polymer itself, a polymer having a graft structure, that is, a polyester having a polyoxyalkylene glycol structure in its side chain has been reported.

For example, according to JP-B-48-8270 and JP-B-49-12915, the formula is

[0006]

[Chemical 3]

(Wherein R ¹ represents an alkylene group, R ² and R ³ each represent an alkyl group or an aromatic group,
It is said that a modified polyester having improved hygroscopicity can be obtained by using a comonomer represented by m ₁ and m ₂ each representing an integer of 1 to 200.

According to Japanese Patent Laid-Open No. 64-9263, the formula

[0009]

[Chemical 4]

(Wherein X represents an aromatic group, R ⁴ and R ⁵ each represent an ester-forming group, and M represents a metal), and a compound containing a metal sulfonate group,

[0011]

[Chemical 5]

Or the expression

[0013]

[Chemical 6]

(In the formula, A ₁ , A ₂ and A ₃ each represent an aliphatic or aromatic hydrocarbon, and P ₁ , P ₂ and P ₃
Is an expression

[(OC₂H_Four) A (OC₃H₆) B] m_Four  (In the formula, a, b, m_FourAre 1 ≦ a ≦ 200 and 0 ≦, respectively.
b <a, 1 ≦ m_FourRepresents an integer that satisfies. )
Represents a polyoxyalkylene group, R⁶, R⁸And R⁹Is
Each represents a hydrocarbon group, R⁷Represents an alkylene group
Then m₃Represents an integer of 1 or more. ) Side chain
Molecular weight consisting mainly of a lialkylene glycol derivative
Mainly 2,000 to 10,000 modified polyester condensates
Polyester consisting of alkylene terephthalate units as
Polyester composition obtained by blending with Ter
Is said to have excellent electrostatic properties and has a relatively high hygroscopic data.
It shows the data. Further, JP-A-1-234420
And according to JP-A-1-236236,

[0016]

[Chemical 7]

(In the formula, R ¹⁰ represents a hydrocarbon group, R ¹¹ represents an alkylene group, and m ₅ represents an integer of 30 to 140) or a comonomer represented by the formula:

[0018]

[Chemical 8]

The copolyester obtained by using the comonomer represented by the formula (wherein R ¹⁰ , R ¹¹ and m ₅ are as defined above) is excellent in hygroscopicity and thermal conductivity,
It is said that when it is made into fibers, it gives a great cooling sensation.

[0020]

The present inventors evaluated the performance of the above various polyoxyalkylene-type side chain-containing copolyesters from the viewpoint of water absorption and water retention in a fiber assembly such as a non-woven fabric. However, in the modified polyesters described in JP-B-48-8270 and JP-B-49-12915, both of the two hydroxyl groups contained in the comonomer are secondary hydroxyl groups which are considered to have poor reactivity. However, it was found that most of the comonomers used in the production of the modified polyester were dispersed in the polyester resin without being incorporated in the polyester molecule. Therefore, it is expected that comonomers dispersed in the resin will elute in the aggregate of fibers made of the modified polyester during washing or use, and retention of water absorption for a long time is not expected. Further, although the polyester composition specifically described in JP-A No. 64-9263 has some improvement in hygroscopicity, it has been found that sufficient water absorption and water retention cannot be achieved. It has also been found that none of the copolymerized polyesters specifically described in JP-A-1-234420 and JP-A-1-236236 can exhibit sufficient water absorption and water retention.

Therefore, an object of the present invention is to provide a method for producing a novel fiber-forming copolymerized polyester capable of exhibiting high water absorption and water retention in the form of a fiber aggregate such as a cloth.

[0022]

Means for Solving the Problems The inventors of the present invention have made earnest studies to achieve the above object, and as a result, the general formula (I)

[0023]

[Chemical 9]

Or the general formula (II)

[0025]

[Chemical 10]

(In the formula, R ₁ and R ₃ each have 1 carbon atom.
~ 18 hydrocarbon groups, R ₂ and R ₄ each represent an ethylene group and / or a propylene group, and n ₁ and n ₂ are numbers 10 to 100 each representing an average degree of polymerization. In some cases, the above object may be achieved by using both the polyoxyalkylene group-containing compound represented by) and the metal salt of dicarboxyarene sulfonic acid or its ester-forming derivative as a copolymerization component of polyester. The present invention has been found, and further investigations have been carried out based on these findings, and the present invention has been achieved.

That is, in the present invention, when at least one difunctional aromatic carboxylic acid or its ester-forming derivative is reacted with at least one diol compound to produce a polyester, the polyester of the general formula (I) is used.

[0028]

[Chemical 11]

Or the general formula (II)

[0030]

[Chemical formula 12]

(In the formula, each of R ₁ and R ₃ has 1 carbon atom.
~ 18 hydrocarbon groups, R ₂ and R ₄ each represent an ethylene group and / or a propylene group, and n ₁ and n ₂ are numbers 10 to 100 each representing an average degree of polymerization. ) A polyoxyalkylene group-containing compound represented by the formula and a dicarboxyarene sulfonic acid metal salt or its ester-forming derivative are added to the reaction system and reacted.
In addition, the method is a method for producing a copolyester, wherein the polycondensation reaction is performed until the intrinsic viscosity of the produced polyester reaches 0.5 dl / g or more.

The copolyester obtained by the production method of the present invention is an aromatic polyester having an aromatic ring in the main chain unit of the polymer, and is a bifunctional aromatic carboxylic acid or its ester-forming derivative. It can be obtained by a polycondensation reaction using a diol compound as a main monomer component.

Examples of the difunctional aromatic carboxylic acid referred to herein include terephthalic acid, isophthalic acid, 1,4-naphthalenedicarboxylic acid, 1,5-naphthalenedicarboxylic acid, 2,5-naphthalenedicarboxylic acid, and 2,6- Naphthalene dicarboxylic acid, 4,
4'-biphenyldicarboxylic acid, 3,3'-biphenyldicarboxylic acid, 4,4'-diphenyletherdicarboxylic acid, 4,4 '
-Diphenylmethanedicarboxylic acid, 4,4'-diphenylisopropylidene dicarboxylic acid, 1,2-bis (phenoxy) ethane-4,4'-dicarboxylic acid, 2,5-anthracene dicarboxylic acid, 2,6-anthracene dicarboxylic acid, Examples thereof include aromatic dicarboxylic acids such as 2,5-pyridinedicarboxylic acid; aromatic hydroxycarboxylic acids such as β-hydroxyethoxybenzoic acid and p-oxybenzoic acid, and terephthalic acid is particularly preferable.

These difunctional aromatic carboxylic acids have 1
There may be only one kind or two or more kinds. In addition to these difunctional aromatic carboxylic acids, bifunctional aliphatic carboxylic acids such as adipic acid, azelaic acid, and sebacic acid; acid components such as bifunctional alicyclic carboxylic acids such as cyclohexanedicarboxylic acid Two or more kinds may be used in combination, but 70 mol% or more of all the acid components used are difunctional aromatic carboxylic acids from the viewpoint that a copolyester having excellent mechanical performance required for fiber applications can be obtained. Especially, terephthalic acid is preferable.

In the present invention, an ester-forming derivative such as a lower alkyl ester thereof may be used as the above acid component. Examples of ester-forming derivatives of difunctional aromatic carboxylic acids include lower alkyl esters such as dimethyl esters of aromatic dicarboxylic acids exemplified above; lower alkyl esters such as methyl esters of aromatic hydroxycarboxylic acids exemplified above. Examples thereof include esters.

The diol compound is ethylene glycol, propylene glycol or trimethylene glycol.
, Tetramethylene glycol, pentamethylene glycol, hexamethylene glycol, nonamethylene glycol, 3-methylpentane-1,5-diol, 2-methyloctane-1,8-diole And aliphatic diols such as diethylene glycol and alicyclic diols such as cyclohexane dimethanol. These diols may be used alone or in combination of two or more, but from the viewpoint that a copolyester having excellent mechanical performance required for fiber applications can be obtained, diol is used. Compound 7
0 mol% or more is a straight chain alkylene glycol having 2 to 6 carbon atoms such as ethylene glycol, trimethylene glycol, tetramethylene glycol, pentamethylene glycol, and hexamethylene glycol. Is desirable. In the present invention, an alkylene oxide such as ethylene oxide may be used as the diol compound.

In the production method of the present invention, the bifunctional aromatic carboxylic acid or the ester-forming derivative thereof as described above,
Monomers mainly composed of difunctional compounds such as diol compounds
For example, triol such as glycerin and trimethylol propane; tetraol such as pentaerythritol; tricarboxylic acid such as trimellitic acid and trimesic acid; tetracarboxylic acid such as pyromellitic acid; A polyfunctional compound having a valence of 3 or more can be used as a copolymerization component in an amount within a range that allows melt molding. In the present invention, the general formula (I)

[0038]

[Chemical 13]

Or the general formula (II)

[0040]

[Chemical 14]

(In the formula, R ₁ and R ₃ each have 1 carbon atom.
~ 18 hydrocarbon groups, R ₂ and R ₄ each represent an ethylene group and / or a propylene group, and n ₁ and n ₂ are numbers 10 to 100 each representing an average degree of polymerization. ) And a polyoxyalkylene group-containing compound represented by the formula (4) are copolymerized with a dicarboxyarene sulfonic acid metal salt or an ester-forming derivative thereof.

In the general formulas (I) and (II), R ₁ and R ₃ each represent a hydrocarbon group having 1 to 18 carbon atoms, preferred examples being methyl, ethyl, n-propyl,
Isopropyl, n-butyl, sec-butyl, tert
-Butyl, n-pentyl, n-octyl, 2-ethylhexyl, n-dodecyl, n-stearyl and the like having 1 carbon atom
~ 18 alkyl group; 3 to 3 carbon atoms such as cyclohexyl
18 cycloalkyl groups; aryl groups having 6 to 18 carbon atoms such as phenyl and nonylphenyl. When the number of carbon atoms in the hydrocarbon groups R ₁ and R ₃ is 19 or more, it is not possible to obtain a copolyester which is excellent in surface wettability and provides a fiber aggregate having excellent water absorption and water retention.
Further, R ₂ and R ₄ each represent an ethylene group and / or a propylene group, and in view of the surface wettability of the resulting copolyester and the high water absorption and water retention properties of the fiber assembly obtained therefrom, an ethylene group is used. Is more preferable. As R ₂ and R ₄ , an ethylene group and a propylene group may coexist in the same polyoxyalkylene group-containing compound molecule. n ₁ and n ₂ are numbers representing the average degree of polymerization of the polyoxyalkylene moiety, and are numbers in the range of 10 to 100. When n ₁ and n ₂ are numbers less than 10, it is not possible to obtain a copolyester which is excellent in surface wettability and provides a fiber assembly having excellent water absorption and water retention. When n ₁ and n ₂ are more than 100, the effects more than those achieved when n ₁ and n ₂ are in the range of 10 to 100 are no longer achieved, and are obtained. It is not preferable because the copolyester tends to be colored. The number of n ₁ and n ₂ is 20 to 20 because the copolyester that gives a fiber assembly that is particularly excellent in surface wettability and that is particularly excellent in water absorption and water retention is obtained while suppressing disadvantages such as coloring as much as possible. A number in the range of 80 is desirable.

As a preferred example of such a polyoxyalkylene group-containing compound, polyoxyethylene glycol-
Methyl-glycidyl ether, polyoxyethylene glycol-methyl-2,3-dihydroxypropyl ether, polyoxyethylene glycol-ethyl-glycidyl ether, polyoxyethylene glycol-ethyl-2,3 -Dihydroxypropyl ether, polyoxyethylene glyco-
-N-propyl-glycidyl ether, polyoxyethylene glycol-n-propyl-2,3-dihydroxypropyl ether, polyoxyethylene glycol-t-butyl
-Glycidyl ether, polyoxyethylene glycol-
t-butyl-2,3-dihydroxypropyl ether, polyoxyethylene glycol-n-octyl-glycidyl ether
Ter, polyoxyethylene glycol-n-octyl-2,3
-Dihydroxypropyl ether, polyoxyethylene glycol-2-ethylhexyl-glycidyl ether,
Polyoxyethylene glycol-2-ethylhexyl-2,3
-Dihydroxypropyl ether, polyoxyethylene glycol-n-dodecyl-glycidyl ether, polyoxyethylene glycol-n-dodecyl-2,3-dihydroxypropyl ether, polyoxyethylene glycol-
n-stearyl-glycidyl ether, polyoxyethylene glycol-n-stearyl-2,3-dihydroxypropyl ether, polyoxyethylene glycol-phenyl-
Glycidyl ether, polyoxyethylene glycol
Phenyl-2,3-dihydroxypropyl ether, polyoxyethylene glycol-nonylphenyl-glycidyl ether, polyoxyethylene glycol-nonylphenyl-2,3-dihydroxypropyl ether, polyoxyethylene glyco -Cyclohexyl-glycidyl ether, polyoxyethylene glycol-cyclohexyl-2,
3-dihydroxypropyl ether, polyoxyethylene glycol / polyoxypropylene glycol copolymer methyl-glycidyl ether, polyoxyethylene glycol / polyoxypropylene glycol copolymer methyl- 2,3-dihydroxypropyl ether, polyoxyethylene glycol / polyoxypropylene glycol
Examples thereof include n-propyl-glycidyl ether which is a copolymer, and n-propyl-2,3-dihydroxypropyl ether which is a polyoxyethylene glycol / polyoxypropylene glycol copolymer. These polyoxyalkylene group-containing compounds may be used alone or in combination of two or more.

Preferred examples of the metal salt of dicarboxyarene sulfonic acid include alkali metal salts of 3,5-dicarboxybenzene sulfonic acid such as 5-sodium sulfoisophthalic acid and 5-potassium sulfoisophthalic acid. Further, examples of the ester-forming derivative of a metal salt of dicarboxyarene sulfonic acid include lower alkyl esters such as dimethyl ester and diethyl ester of the above-mentioned alkali metal salt of 3,5-carboxybenzene sulfonic acid.

In the production method of the present invention, a polycondensation reaction is carried out until the intrinsic viscosity of the produced polyester in a mixed solvent of equal weight of phenol and tetrachloroethane at 30 ° C. is 0.5 dl / g or more. With a copolyester having an intrinsic viscosity of less than 0.5 dl / g, mechanical properties such as strength will be insufficient, and the yarn will be severely broken when subjected to melt spinning. On the other hand, in the case of a copolyester having an intrinsic viscosity of more than 1.5 dl / g, the melt viscosity may be too high, resulting in poor spinnability. From the viewpoint that mechanical properties are particularly good and troubles in the fiberizing process can be reduced, the polycondensation reaction time is such that the intrinsic viscosity of the obtained copolyester is within the range of 0.5 to 1.5 dl / g. Is preferable, and the time is preferably in the range of 0.6 to 1.0 dl / g.

In the production method of the present invention, for example, JP-A 1-2
An operation according to a known method described in JP-A-34420, JP-A-1-236236, etc. is adopted. For example, the production method of the present invention comprises directly esterifying a desired difunctional aromatic carboxylic acid such as terephthalic acid with a desired diol such as ethylene glycol,
Transesterification of the desired difunctional aromatic carboxylic acid ester-forming derivative, such as a lower alkyl ester of terephthalic acid, such as dimethyl terephthalate, with the desired diol, such as ethylene glycol; The first step of forming an ester of a difunctional aromatic carboxylic acid and a diol compound or a low polymer thereof, which comprises reacting a difunctional aromatic carboxylic acid with a desired alkylene oxide such as ethylene oxide. It can be carried out by a reaction followed by a second stage reaction consisting of heating the product under reduced pressure to polycondense it to the desired degree of polymerization. A known catalyst can be used in these reactions. Examples of such catalysts include zinc compounds such as zinc acetate, zinc carbonate, manganese acetate, manganese compounds such as manganese carbonate, calcium acetate, calcium compounds such as calcium carbonate, cobalt acetate, cobalt compounds such as cobalt carbonate, barium acetate, Transesterification catalysts such as barium compounds such as barium carbonate; antimony compounds such as antimony oxide, germanium compounds such as germanium oxide, and polycondensation catalysts such as titanium compounds such as tetraisopropyl orthotitanate.

In order to copolymerize the polyoxyalkylene group-containing compound represented by the general formula (I) or (II) into the above polyester molecule, at any stage until the above-mentioned polycondensation reaction is completed, for example, Before the start of the first stage reaction,
During the reaction, after completion of the reaction, the polyoxyalkylene group-containing compound may be added to the reaction system at any stage such as during the second stage reaction, and the reaction may be completed after the addition. At this time, the amount of the polyoxyalkylene group-containing compound used is preferably an amount within the range of 1 to 50% by weight, and an amount within the range of 5 to 30% by weight, based on the resulting copolyester. Is more preferable. If the addition amount of the polyoxyalkylene group-containing compound is less than 1% by weight, the surface wettability of the obtained copolyester may be insufficient, and if it exceeds 50% by weight, the strength of the obtained copolyester may be insufficient. Mechanical performance may decrease. In addition, in order to copolymerize the metal salt of dicarboxyarene sulfonic acid or its ester-forming derivative with the above-mentioned polyester molecule, in the synthesis of the above-mentioned polyester, any of before the start of the reaction in the first step, during the reaction, or after the end of the reaction is optional. In the step 2, the metal salt of dicarboxyarene sulfonic acid or its ester-forming derivative may be added to the reaction system, and after the addition, the polycondensation reaction in the second step may be completed. At this time, the amount of the metal salt of dicarboxyarene sulfonic acid or its ester-forming derivative used is determined by the total amount of the acid used such as metal salt of dicarboxyarene sulfonic acid, difunctional aromatic carboxylic acid, or their ester-forming derivative. The amount of the component is preferably in the range of 0.5 to 10 mol%, more preferably 1 to 7 mol%. If the amount of the metal salt of dicarboxyarene sulfonic acid or its ester-forming derivative used is less than 0.5 mol%, the surface wettability of the resulting copolyester may be insufficient, and if it exceeds 10 mol%. In this case, thickening occurs during the polymerization due to the ionic interaction of the dicarboxyarene sulfonic acid metal salt component, making it difficult to continue the polycondensation reaction until the resulting polyester has a desired intrinsic viscosity. There is a risk of becoming. Regarding the relative proportions of the amount of the polyoxyalkylene group-containing compound used and the amount of the dicarboxyarene sulfonic acid metal salt or its ester-forming derivative used,
The weight percentage of the polyoxyalkylene group-containing compound used on the basis of the produced copolyester is Y (wt%)
When the sum of the mole percentages of the dicarboxyarene sulfonic acid metal salt and its ester-forming derivative used on the basis of the total acid components used is represented by (mol%),
It is preferable that the value of Y / Z is within the range of 2 to 30 because a copolyester having particularly improved both surface wettability and mechanical properties can be obtained.

The reason why the copolyester obtained by the production method of the present invention shows high water absorption and water retention in the form of an aggregate such as a non-woven fabric when formed into fibers is not clear at present. Although not present, the present inventors derived from a side chain polyoxyalkylene chain derived from the polyoxyalkylene group-containing compound represented by the general formula (I) or (II) and a dicarboxyarene sulfonic acid metal salt component. It is presumed that the metal salt type sulfonic acid group may have some synergistic effect in the state of being copolymerized in the polyester molecule.

The copolymerized polyester obtained by the production method of the present invention may contain optional additives such as a coloring inhibitor, a heat-resistant agent, a fluorescent bleaching agent, a flame retardant, an antioxidant, if necessary.
Matting agents, colorants, inorganic fine particles and the like may be contained.

It is generally known that polyoxyalkylene chains are easily oxidized by oxygen in the air. Also in the copolyester obtained in the present invention, the polyoxyalkylene chain portion may be oxidized under high temperature conditions such as polycondensation reaction and melt spinning conditions, and there is a risk that the degree of polymerization may be reduced or coloring may occur. The addition of antioxidants is preferred. The antioxidant can be classified into a chain initiation inhibitor, a radical chain inhibitor, a peroxide decomposing agent, etc. according to its action mechanism, but the copolymerized polyester obtained by the present invention is classified as a radical chain inhibitor. Antioxidants are excellent in effect, and among them, hindered phenol type antioxidants are suitable.

The hindered phenol type antioxidant as used herein is a phenol having a sterically hindering substituent on both or one of two carbon atoms adjacent to the carbon atom having the phenolic hydroxyl group. It is a ruthenium compound. As the sterically hindering substituent here, a tertiary alkyl group such as t-butyl group is most preferable. Specific preferred examples of the hindered phenol type antioxidants include the following hindered phenol type compounds.

[0052]

[Chemical 15]

[0053]

[Chemical 16]

[0054]

[Chemical 17]

[0055]

[Chemical 18]

[0056]

[Chemical 19]

The above-mentioned hindered phenol antioxidants may be used alone or in combination of two or more.
Further, the hindered phenol-based antioxidant may be used in combination with another antioxidant. Especially when combined with a phosphorus-based antioxidant such as triphenylphosphite, an antioxidant classified as a peroxide decomposing agent such as a sulfur-based antioxidant such as dilaurylthiodipropionate, etc., By synergistic action with the hindered phenol type antioxidant,
A higher antioxidant effect may be obtained. On this occasion,
The amount of the hindered phenol antioxidant used is 0.2 to 20% by weight based on the polyoxyalkylene group-containing compound represented by the general formula (I) or (II).
The amount is preferably in the range of 0.5 to 10
It is more preferable that the amount is within the range of wt%. If the addition amount of the hindered phenol type antioxidant is less than 0.2% by weight, the obtained antioxidant effect may be insufficient, and if it exceeds 20% by weight, the obtained antioxidant effect may no longer be obtained. No significant improvement is observed, and conversely, there is a risk of causing troubles such as single yarn breakage in the spinning process, and further, the mechanical performance of the resulting fiber may be reduced.

In the manufacturing method of the present invention, such a hinder
In order to compound the dophenol-based antioxidant in the above-mentioned copolymerized polyester, the polycondensation reaction described above is completed and at any stage after the completion, for example, before the start of the reaction in the first stage, during the reaction, After the completion of the reaction, the hindered phenol type antioxidant may be added at any stage such as before the start of the second stage reaction, during the reaction, after the completion of the reaction and the like.

As a method for molding the copolyester obtained by the production method of the present invention, it is not necessary to employ a special method, and a melt molding method can be arbitrarily adopted as in the case of ordinary polyesters, such as fibers, films and sheets. It is possible to obtain any molded product such as a grate. For example, when forming into fibers, a melt spinning method can be adopted. The fiber made of the copolyester obtained by the production method of the present invention has a circular shape by selecting the shape of the nozzle used; or a trilobal shape, a tetralobal shape, a pentalobe shape, a hexalobe shape, a heptalobular shape, an octalobe shape. It may have an arbitrary cross-sectional shape such as a multi-leaf shape such as, or a T shape, and may be a hollow fiber without being limited to a solid fiber. The spun raw yarn produced by melt spinning the copolyester obtained by the production method of the present invention can be made into a drawn yarn by drawing according to a conventional method. The drawn yarn can be further subjected to desired post-treatments such as heat treatment, crimping and cutting according to a conventional method.

From the point that the high surface wettability of the copolyester obtained by the production method of the present invention is effectively reflected in the water absorption and the water retention in the fiber assembly, the fiber has a large specific surface area. desirable. From this point of view, it is desirable that the single yarn denier of the fiber is 5 denier or less, and it may be advantageous that the cross-sectional shape is a multi-lobed shape, a T-shaped cross-sectional shape having concave portions, or the like. is there. The copolymerized polyester obtained by the production method of the present invention may be combined with another resin to form a so-called core-sheath structure or dorso-ventral structure conjugate fiber. In this case, the copolymerized polyester obtained by the production method of the present invention is It is preferable to dispose the fiber so as to occupy 20% or more, especially 40% or more of the fiber surface from the viewpoint that the high surface wettability of the copolyester is effectively exhibited.

The fiber made of the copolyester obtained by the production method of the present invention can be made into a fiber product such as a cloth such as a non-woven fabric by itself, but it can be mixed with other fibers to obtain a fiber product such as a cloth. Good.

[0062]

The present invention will be described in detail below with reference to examples, but the present invention is not limited to these examples. Moreover, each physical property value in an Example is a value obtained by measuring according to the following method.

(1) Intrinsic viscosity of polymer [η] Using an equal weight mixed solvent of phenol and tetrachloroethane, 0.25 g / dl and 0.50 g of the target polymer are used.
/ Dl and 1.0 g / dl at three concentrations, determined from the three reduced viscosities measured at a temperature of 30 ° C.

(2) Melting point of polymer Tm Using a TA-3000 type DSC (differential scanning calorimeter) manufactured by Metra Co., Ltd., the temperature was measured at a temperature rising rate of 10 ° C./min for a sample in a rapidly cooled amorphous state. ..

(3) Surface wettability of polymer The surface wettability of the polymer was evaluated by the contact angle of the polymer film and water. The method for preparing the polymer film used as the test piece is as follows. That is, the target polymer chip was dried under reduced pressure at 120 ° C. for 12 hours, and then melted by heating at 280 ° C. for 5 minutes, and a stainless plate having a thickness of 1 mm, a Teflon sheet having a thickness of 0.3 mm, and a thickness of 0.3 mm were used. 0.2
mm Teflon spacer, 0.3 mm thick Teflon sheet, and 1 mm thick stainless plate laminated in this order between two Teflon sheets. In this state, it was pressed at 280 ° C. for 1 minute, and immediately thereafter, it was pressed for 1 minute using a water-cooling type cooling press to prepare a polymer film.

The test method is as follows. A test piece of a polymer film is washed with acetone, air-dried, the film is placed horizontally on a flat surface, and water is dropped onto the film so that the contact diameter is about 3 mm or less. The contact angle of the water droplet formed by the film with the film was measured by a Kyowa Interface Science Co., Ltd. CA-DT contact angle meter.

(4) Water Absorption of Polymer The water absorption of the polymer was evaluated by determining the water absorption rate against water and the repeated liquid absorption rate after the polymer was made into a fiber and further made into a nonwoven fabric. The polymer was spun with a circular nozzle at 285 ° C., stretched in warm water at 75 ° C., heat-fixed, and then mechanically crimped to give an oil solution containing stearyl phosphate as an ethylene oxide adduct as a main component. 1% by weight, relaxation heat treatment at 150 ° C. for 10 minutes, then 5
It was cut to a length of 1 mm to obtain raw cotton of single yarn denier 2.0. Next, 2 pieces of heat-fusible fibers (sofait N-710 type, 2 denier, 51 mm, manufactured by Kuraray Co., Ltd. in which the sheath component is formed of polyethylene component) are added to the raw cotton.
Blended with 0% by weight and then passed through a card to give a basis weight of about 40 g /
m ² web was prepared, and then 5 m / min. The water was entangled at a rate of 30 kg / cm < ² > at a rate of 1, then air-dried, and then heat-treated at 150 [deg.] C. for 1 minute in an auto dryer to obtain a nonwoven fabric. The nonwoven fabric thus obtained was used as a sample for measuring water absorption (initial performance).

The washing treatment of the sample for measuring water absorption was performed according to JIS0.
It was carried out according to the No. 103 method in the washing method specified in 217. That is, 2 liters of water at 40 ° C
A synthetic detergent for clothing was added at a ratio of g and dissolved to obtain a washing liquid. A sample and a load cloth as needed were added to this washing liquid so that the bath ratio became 1:30, and the operation of the domestic washing machine was started. After treatment for 5 minutes, the operation was stopped, the sample and the load cloth were dehydrated by a centrifugal dehydrator, and then the washing liquid was replaced with fresh water at room temperature, followed by rinsing with the same bath ratio for 2 minutes and then dehydration. It was rinsed again for 2 minutes and air dried. The above operation was repeated 10 times in total to obtain a sample for measuring water absorption after washing 10 times.

Explaining the test method, 0.2 g of water colored with red ink was dropped on a plastic dish, and a 5 cm × 5 cm sample for water absorption measurement was placed on the red ink and removed after 1 second. The weight of the liquid absorbed by the sample was measured. The liquid absorption rate was calculated from the weight (W) of the sample absorbed and the weight (W ₁ ) of the sample before the liquid absorption by the following formula. This measurement was repeated 10 times, and the arithmetic average value of these measured values was defined as the liquid absorption rate. Liquid absorption rate (%) = _{[(W-W 1) / W} 1 ] × 100

Repeated measurement of the liquid absorption rate was 5 cm ×
When a 5 cm sample for water absorption measurement was dropped on the water surface, the time taken for the water to spread over the entire surface of the sample was measured and used as the liquid absorption speed. The sample used for the measurement was sufficiently dried, and then the same measurement and drying were repeated, and the arithmetic average value of the values of the liquid absorption rates obtained by performing 10 times in total was defined as the liquid absorption rate.

Examples 1 to 3 971.9 g of terephthalic acid, 40.2 g of 5-sodium sulfoisophthalic acid and 750 g of ethylene glycol.
Was charged into an esterification reactor, and at 230 ° C., 2.5 kg /
The esterification reaction was carried out for 2 hours under a pressure of cm ² . Then, the obtained reaction product was transferred to a polycondensator previously heated to 230 ° C.

[0072]

[Chemical 20]

The polyoxyethylene group-containing compound represented by the formula (1) was added in an amount shown in Table 1, and the comonomer was further added.
5% by weight of 1,3,5-tris (4-t-
Butyl-3-hydroxy-2,6-dimethylbenzyl)
-1,3,5-triazine-2,4,6- (1H, 3
H, 5H) -trion (American Cyanamid, Syanox 1790), antimony trioxide 0.
A polycondensation reaction system was prepared by adding 4 g and 0.12 g of phosphorous acid. The temperature of the polycondensation reaction system is from 230 ° C to 280
Gradually increase to 0.1 mmHg while raising the temperature to ℃ over 45 minutes
After reducing the pressure to 280 ° C., the melt viscosity of the system at 280 ° C. is 2 times that of polyethylene terephthalate having an intrinsic viscosity of 0.70 dl / g.
By continuing the polycondensation reaction until the melt viscosity at 80 ° C. was substantially matched, the corresponding copolyesters were obtained.

Table 1 shows polymer physical properties, polymer film surface wettability evaluation results, and nonwoven fabric water absorption evaluation results for the obtained copolyester.

Example 4 In Example 1, 44.2 g of dimethyl 5-sodium sulfoisophthalate was used instead of 40.2 g of 5-sodium sulfoisophthalic acid, and 5% by weight based on the polyoxyethylene group-containing compound. Amount of 1,3,5-tris (4-t-butyl-3-hydroxy-2,6-dimethylbenzyl) -1,3,5-triazine-2,4,6-
Instead of (1H, 3H, 5H) -trione (manufactured by American Cyanamid, Syanox 1790), pentaerythyryl-tetrakis [3- (3,3,3 5-di-t
-Butyl-4-hydroxyphenyl) propionate]
Corresponding copolyesters were obtained in the same manner except that (Ciba-Gagi Co., Ltd., Irganox 1010) was used. Table 1 shows the polymer physical properties, polymer film surface wettability evaluation results, and nonwoven fabric water absorption evaluation results for the obtained copolyester.

Examples 5 to 12 In Example 1, instead of the polyoxyethylene group-containing compound as one of the comonomers, the corresponding polyoxyalkylene group-containing compound represented by the following formula is shown in Table 1.
Corresponding copolyesters were obtained in the same manner except that only the amount shown in 1 was used.

Comonomers used in Example 5:

[Chemical 21]

Comonomers used in Example 6:

[Chemical formula 22]

Comonomers used in Example 7:

[Chemical formula 23]

Comonomers used in Example 8:

[Chemical formula 24]

Comonomers used in Example 9:

[Chemical 25]

Comonomers used in Example 10:

[Chemical formula 26]

Comonomers used in Example 11:

[Chemical 27]

Comonomers used in Example 12:

[Chemical 28]

Table 1 shows polymer physical properties, polymer film surface wettability evaluation results and nonwoven fabric water absorption evaluation results for the obtained copolyester.

Example 13 971.9 g of terephthalic acid in Example 1 and 5
A corresponding copolyester was obtained in the same manner except that 986.8 g of terephthalic acid and 16.1 g of 5-sodium sulfoisophthalic acid were respectively used instead of 40.2 g of sodium sulfoisophthalic acid. Regarding the obtained copolyester, polymer physical properties and polymer
Table 1 shows the evaluation results of the surface wettability of the film and the evaluation results of the water absorption of the nonwoven fabric.

Example 14 In Example 1, 971.9 g of terephthalic acid and 5
Corresponding copolyesters were obtained in the same manner, except that 947.0 g of terephthalic acid and 80.41 g of 5-sodium sulfoisophthalic acid were used instead of 40.2 g of sodium sulfoisophthalic acid, respectively. Table 1 shows the polymer physical properties, polymer film surface wettability evaluation results, and nonwoven fabric water absorption evaluation results for the obtained copolyester.

Example 15 In Example 1, instead of the polyoxyethylene group-containing compound, polyoxyethylene glycol / polyoxypropylene glycol in which the average degree of polymerization of oxyethylene units and oxypropylene units were 35 and 5, respectively. A corresponding copolyester was obtained in the same manner except that the n-butyl-glycidyl ether of the copolymer was used in an amount of 10% by weight based on the obtained polymer. Table 1 shows the polymer physical properties, polymer film surface wettability evaluation results, and nonwoven fabric water absorption evaluation results for the obtained copolyester.

Example 16 In Example 1, instead of 971.9 g of terephthalic acid, 923.3 g of terephthalic acid and 48.6 g of isophthalic acid were used.
A corresponding copolyester was obtained in the same manner except that the mixture of was used. Table 1 shows the polymer physical properties, polymer film surface wettability evaluation results, and nonwoven fabric water absorption evaluation results for the obtained copolyester.

Example 17 Corresponding in the same manner as in Example 1 except that instead of 750 g of ethylene glycol, a mixture of 712.5 g of ethylene glycol and 43.4 g of 1,4-cyclohexanedimethanol was used. A copolymerized polyester was obtained. Table 1 shows the polymer physical properties, polymer film surface wettability evaluation results, and nonwoven fabric water absorption evaluation results for the obtained copolyester.

[0091]

[Table 1] In Table 1, (Note 1) is shown as a percentage of the weight of the polyoxyalkylene group-containing compound to be added based on the weight of the obtained polymer, and (Note 2) is 5 based on the total acid component used as the monomer. -Indicated by the mole percentage of sodium sulfoisophthalic acid or its dimethyl ester.

Comparative Example 1 Polyester (polyethylene terephthalate) was prepared in the same manner as in Example 1 except that no comonomer was used.
Got Table 2 shows polymer physical properties, polymer film surface wettability evaluation results, and nonwoven fabric water absorption evaluation results for the obtained polyester.

Comparative Example 2 A copolyester was obtained in the same manner as in Example 1 except that the polyoxyethylene group-containing compound was not used.
About the obtained copolyester, polymer physical properties,
Table 2 shows the surface wettability evaluation results of the polymer film and the water absorption evaluation results of the nonwoven fabric.

Comparative Example 3 In Example 1, 971.9 g of terephthalic acid and
A corresponding copolyester was obtained in the same manner except that 996.8 g of terephthalic acid was used instead of 40.2 g of 5-sodium sulfoisophthalic acid. Table 2 shows polymer physical properties, polymer film surface wettability evaluation results, and nonwoven fabric water absorption evaluation results for the obtained copolyester.

Comparative Examples 4 and 5 In Example 1, except that a polyoxyethylene group-containing compound represented by the following formula was used as one of the comonomers instead of the polyoxyethylene group-containing compound in an amount shown in Table 2. In the same manner, corresponding copolyesters were obtained.

Comonomers used in Comparative Example 4:

[Chemical 29]

Comonomers used in Comparative Example 5:

[Chemical 30]

For each of the obtained copolyesters,
Table 2 shows the polymer physical properties, the polymer film surface wettability evaluation results, and the nonwoven fabric water absorption evaluation results.

[0099]

[Table 2] In (Note 1), the percentage of the weight of the added polyoxyalkylene group-containing compound based on the weight of the obtained polymer is shown, and (Note 2) is the amount of 5-sodium based on the total acid component used as the monomer. It is shown as a molar percentage of sulfoisophthalic acid.

COMPARATIVE EXAMPLE 6 In Example 1, 971.9 g of terephthalic acid and 5
Corresponding copolyesters were obtained in the same manner except that 917.1 g of terephthalic acid and 128.7 g of 5-sodium sulfoisophthalic acid were used instead of 40.2 g of sodium sulfoisophthalic acid. [Η] of the obtained copolyester was 0.41 dl / g. When this copolyester was made into fibers, the fibers were frequently cut during spinning, and the resulting spun raw yarn also had poor drawability, so it could not be evaluated as a nonwoven fabric.

[0101]

According to the production method of the present invention, a fiber-forming copolymerized polyester having high surface wettability can be obtained. When the copolyester is made into fibers, it exhibits excellent water absorption and water retention in the form of a fiber aggregate such as a cloth such as a nonwoven fabric, and even when it is subjected to a treatment such as washing, the water absorption and Water retention can be maintained for a long period of time.

Claims (1)

[Claims] 1. When a polyester is produced by reacting at least one difunctional aromatic carboxylic acid or its ester-forming derivative with at least one diol compound, a polyester of the general formula (I): Or the general formula (II) (In the formula, R ₁ and R ₃ each represent a hydrocarbon group having 1 to 18 carbon atoms, R ₂ and R ₄ each represent an ethylene group and / or a propylene group, and n ₁ and n ₂ each represent an average degree of polymerization. Which is a number from 10 to 100) and a metal salt of dicarboxyarene sulfonic acid or an ester-forming derivative thereof are added to the reaction system to cause a reaction, A method for producing a copolyester, comprising carrying out a polycondensation reaction until the intrinsic viscosity of the polyester becomes 0.5 dl / g or more.