JPH05321108A - Nonwoven fabric excellent in water absorbing performance - Google Patents

Abstract

PURPOSE:To obtain a nonwoven fabric, comprising specific hydrophilic polyester- based synthetic fiber as a principal constituent element and having a high strength and durable water absorptivity and water holding properties. CONSTITUTION:The objective nonwoven fabric comprises hydrophilic polyester- based synthetic fiber obtained by blending and copolymerizing hydrophilic monomers having (A) a dicarboxylic acid unit, (B) a diol unit, (C) a structural unit expressed by formula I [(x) and (y) are 0 or 1; Z is monovalent group expressed by formula II (R1 is 1-18C hydrocarbon; R2 is alkylene; n1 is the average polymerization degree and 10-100)], (D) a structural unit expressed by formula III (R3 is alkylene; n2 is same as n1) and (E) a structural unit expressed by formula TV (Ar is trivalent aromatic group; M is metallic atom) so as to provide 1-49wt.% each of the components (C) and (D), 2-50wt.% total amount thereof and 0.5-10mol% component (E) based on the total acid components constituting the polyester as a principal element. This hydrophilic polyester-based synthetic fiber has <=40g/denier Young's modulus in water at 20 deg.C and <=80% based on the Young's modulus in air at 20 deg.C and 65% RH.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a non-woven fabric suitable for use in medical applications such as facing materials, wiping cloth interlinings, clothing, disposable surgical clothing, etc.

[0002]

2. Description of the Related Art In recent years, the frequency of use of polyester fibers represented by polyethylene terephthalate has increased in the field of fibers, particularly in the field of nonwoven fabrics. Baby
Hygienic material fields such as diapers, diaper liners, and sanitary products,
Nonwoven fabrics made of polyester fiber are used in non-hygienic materials such as counter cloths for the food service industry and drainage bags for kitchen sinks, medical cloths such as ship medicine base cloths and fixed sheets, surgical gowns and masks. It has been widely used. Among these non-woven products, particularly for baby diapers and sanitary products, the water absorption performance is required to be more durable than conventional ones.

[0003]

Conventionally, water absorption performance has been imparted by a so-called post-processing method in which the surface of a nonwoven fabric is treated with an oil agent or the like, but this method has initial performance,
When used to a certain extent, the surface oil agent of the non-woven fabric falls off and the water absorption performance is extremely deteriorated, which limits its use. In particular, the non-woven fabric for wet use, which is used as the surface material of diapers and the surface material of sanitary pads, always undergoes a papermaking process in water during the manufacturing process. Sometimes the hydrophilizing agent falls off, and many of the final products do not retain sufficient performance.

Further, as a method for producing a non-woven fabric, there are spun lace, spun bond, jet spinning method and the like, but all of them usually have some means for concentrating fibers to maintain the shape of the cloth. Is normal. That is, for example, means such as entanglement between fibers, adhesion using a binder, and heat adhesion. Among them, the entanglement method by high-pressure water jet punching (water-jet punching) has been widely practiced because of its simplicity, but fibers such as polyester fiber having hydrophobicity and relatively large Young's modulus are considerably high-pressure water jet. The entanglement is insufficient unless processed in. Therefore, the non-woven fabric thus obtained has a low strength and the appearance is only poor. On the other hand, hydrophilic fibers such as rayon fibers and having a low Young's modulus when wet tend to give a nonwoven fabric having a good entangled state even with relatively low-pressure water flow treatment.

An object of the present invention is to provide a nonwoven fabric made of polyester fiber which exhibits high water absorption performance and water retention performance for a long period of time and is excellent in hydroentanglement.

[0006]

According to the present invention, the above object is to have a Young's modulus in water at 20 ° C. of 40 g / denier or less and a Young's modulus in water at 20 ° C. of 20 ° C. , A non-woven fabric containing, as a main component, a hydrophilic polyester-based synthetic fiber having a Young's modulus of 80% or less in air at 65% RH. The hydrophilic polyester-based synthetic fiber is not particularly limited as long as it is a hydrophilic fiber having a Young's modulus as described above, but is a hydrophilic fiber that is hydrophilic from the inside of the fiber, such as hydrophilic monomer-copolymerized polyester. It may be present after the modification of hydrophobic fibers such as polyester and polyolefin, for example, a method of applying a hydrophilic monomer by grafting, a method of applying a hydrophilic group by low-temperature plasma treatment, and a coating of a polymer with a hydrophilizing agent. For example, the fiber surface may be hydrophilic.

In the present invention, polyesters obtained by copolymerizing the following hydrophilic monomers are preferred. That is, mainly dicarboxylic acid units, diol units, and general formula (I)

[Chemical 3] [In the Formula, x and y represent 0 or 1 respectively, Z is a formula -O- (R ↓ 2-O) n ↓ 1-R ↓ 1 (In formula, R ↓ 1 is carbonization of C1-C18. Represents a hydrogen group,
R ↓ 2 represents an alkylene group, and n ↓ 1 represents a monovalent group represented by 10 to 100 representing the average degree of polymerization].

The structural unit represented by the general formula (II)

-O- (R ↓ 3-O) n ↓ 2-

(In the formula, R ↓ 3 represents an alkylene group, and n
↓ 2 is a number from 10 to 100 that represents the average degree of polymerization)

The structural unit represented by the general formula (II)
I)

[0012]

[Chemical 4]

(In the formula, Ar represents a trivalent aromatic group, and M
Represents a metal atom)

The structural units represented by the formulas (I) and (II) have a content of 1 to 49% by weight, respectively. The total content of structural units represented by the formula (2) is 2 to 50% by weight, and the content of the structural units represented by the general formula (III) is 0. It is a copolyester of 5 to 10 mol%.

One of the constitutional units of the above-mentioned copolyester
The dicarboxylic acid unit is a structural unit in which two hydroxyl groups in two carboxyl groups are removed from the dicarboxylic acid molecule,

[0016]

[Chemical 5]

(In the formula, R ↓ 4 represents a divalent organic group)

It is indicated by Examples of the divalent organic group represented by R ↓ 4 include divalent aromatic hydrocarbon groups such as p-phenylene group, m-phenylene group, naphthalenediyl group and (biphenyl) diyl group; octamethylene group, A divalent aliphatic hydrocarbon group such as a tetramethylene group; and a divalent alicyclic hydrocarbon group such as a 1,4-cyclohexyl group.

The dicarboxylic acid unit contained in the copolyester may be only one kind or two or more kinds. However, a copolyester having excellent mechanical performance required for fiber applications can be obtained. From the viewpoint of obtaining, it is preferable that 70 mol% or more of the dicarboxylic acid unit is a terephthaloyl group.

One of the constitutional units of the above-mentioned copolyester
The diol unit, which is one, is a structural unit in which two hydrogen atoms in two hydroxyl groups are removed from the molecule of diol,
General formula

-0-R ↓ 5-O-

(In the formula, R ↓ 5 represents a divalent organic group)

It is shown by. As the divalent organic group represented by R ↓ 5, for example, ethylene group, trimethylene group, pentamethylene group, hexamethylene group, 2,2-dimethyltrimethylene group, 3-methylpentamethylene group, nonamethylene group, 2- Divalent aliphatic hydrocarbon group such as methyloctamethylene group; Divalent alicyclic hydrocarbon group such as dimethylcyclohexane-α, α′-diyl group; 2,2-diphenylpropane-4 ′, 4 ″ And divalent aromatic groups such as a diyl group and a diphenylsulfone-4,4′-diyl group.

The diol unit contained in the polymerized polyester may be only one kind or two or more kinds, but a copolymerized polyester having excellent mechanical performance required for fiber applications is used. From the viewpoint of obtaining, 70 mol% or more of the diol unit has 2 carbon atoms such as ethylenedioxy group, trimethylenedioxy group, tetramethylenedioxy group, pentamethylenedioxy group, hexamethylenedioxy group and the like. It is preferably a divalent structural unit in a form in which two hydrogen atoms in two hydroxyl groups are removed from the molecule of linear alkylene glycol of ~ 6.

One of the structural units of the above copolymerized polyester
The structural unit represented by the general formula (I) is one of the general formula (I-1)

[0026]

[Chemical 6]

(Where Z is as defined above)

The structural unit represented by the general formula (I-2)

[0029]

[Chemical 7]

(Where Z is as defined above)

The structural unit represented by the general formula (I-3)

[0032]

[Chemical 8]

(In the formula, Z is as defined above) and the like. The structural unit represented by the general formula (I) is usually an ester bond (-CO-O-) or an ether bond between them or with other structural units such as the above dicarboxylic acid unit and diol unit. (-O-)
Are incorporated into the main chain of the copolyester of the present invention to form a side chain type polyoxyalkylene structure. The hydrocarbon group represented by R ↓ 1 in the formula representing the group Z is methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, n-pentyl, n-octyl, 2 -Ethylhexyl, n-dodecyl, n-stearyl and the like having 1 to 18 carbon atoms
And an alkyl group having 3 to 18 carbon atoms such as cyclohexyl; and an aryl group having 6 to 18 carbon atoms such as phenyl and nonylphenyl. Hydrocarbon group R ↓
When the carbon number of 1 is 19 or more, a fiber having excellent surface wettability and excellent water absorption and water retention cannot be obtained.
Further, the alkylene group represented by R ↓ 2 in the formula representing the group Z is preferably an alkylene group having 2 to 4 carbon atoms such as ethylene group and propylene group, and a fiber excellent in surface wettability, water absorption and water retention is obtained. The ethylene group is more preferable because it can be obtained. As R ↓ 2, plural kinds of alkylene groups may be present at the same time, such as a combination of an ethylene group and a propylene group. N ↓ 1 in the formula representing the group Z is a number representing the average degree of polymerization of the polyoxyalkylene moiety, and is 10 to 100.
Is a number in the range. When n ↓ 1 is less than 10, a fiber having excellent surface wettability, water absorption and water retention cannot be obtained. On the other hand, when n ↓ 1 is more than 100, the effects of surface wettability, water absorption, water retention, etc. reach saturation, and rather the fibers are likely to be colored. In terms of surface wettability, water absorption, water retention, coloring, etc., n ↓ 1 is preferably a number within the range of 20 to 90.

One of the constitutional units of the above-mentioned copolyester
The structural unit represented by the general formula (II), which is one of the two, is usually incorporated into the main chain of the copolyester by forming an ester bond with the dicarboxylic acid unit or the structural unit represented by the general formula (III). To form a main chain type polyalkylene structure. As the alkylene group represented by R ↓ 3 in the general formula (II), an alkylene group having 2 to 4 carbon atoms such as ethylene group and propylene group is preferable, and a fiber excellent in surface wettability, water absorption and water retention is obtained. Therefore, the ethylene group is more preferable. As R ↓ 3, plural kinds of alkylene groups may be present at the same time, such as a combination of an ethylene group and a propylene group. N ↓ in the general formula (II)
2 is a number that represents the average degree of polymerization of the polyoxyalkylene moiety, and is a number within the range of 10 to 100. n ↓ 2 is 10
When the number is less than the above value, fibers having excellent surface wettability, water absorption and water retention cannot be obtained. On the other hand, n ↓ 2 is 100
When the number is more than 10, the effects of surface wettability, water absorption, water retention, etc. reach saturation, and rather, the fibers are likely to be colored. From the viewpoint of surface wettability, water absorption, water retention, coloring, etc., n ↓ 2 is preferably a number within the range of 20 to 90.

The structural unit represented by the general formula (I) and the structural unit represented by the general formula (II) contained in the copolyester may each be only one kind, or 2
The content of the structural unit represented by the general formula (I) and the structural unit represented by the general formula (II) are each in the range of 1 to 49% by weight, and The structural unit represented by the general formula (I) and the general formula (I
It is necessary that the total content of the structural units represented by I) is in the range of 2 to 50% by weight, preferably in the range of 3 to 40% by weight, and 5 to 3% with respect to the copolyester.
The range of 0% by weight is particularly preferable. When the total content of the structural unit represented by the general formula (I) and the structural unit represented by the general formula (II) is less than 2% by weight, the surface wettability of the obtained fiber may be insufficient. Yes, 50% by weight
If it exceeds, mechanical strength such as strength of the obtained fiber may be deteriorated.

One of the structural units of the above copolymerized polyester
The structural unit represented by the general formula (III), which is one, is usually the above-mentioned diol unit, the structural unit represented by the general formula (I),
Alternatively, it is incorporated into the main chain of the copolyester by forming an ester bond with the structural unit represented by the general formula (II). Ar in the general formula (III) represents a trivalent aromatic group, a 1,3,5-benzenetriyl group, 1,
Benzenetriyl groups such as 2,3-benzenetriyl group and 1,2,4-benzenetriyl group; 1,3,6-naphthalenetriyl group, 1,3,7-naphthalenetriyl group,
Examples thereof include naphthalenetriyl groups such as 1,4,5-naphthalenetriyl group and 1,4,6-naphthalenetriyl group. M represents a metal atom, and alkali metals such as lithium, sodium and potassium are preferable.

The general formula (I
The structural unit represented by II) may be only one kind or two or more kinds, but the content of the structural unit represented by the general formula (III) is contained in the copolymerized polyester. It is an amount within the range of 0.5 to 10 mol% in the total acid components, and preferably within the range of 1 to 7 mol%. If the content of the structural unit represented by the general formula (III) is less than 0.5 mol%, the resulting nonwoven fabric may have insufficient surface wettability. If it exceeds 10 mol%,
The polycondensation reaction is carried out until thickening occurs during the polycondensation reaction due to the ionic interaction of the metal sulfonate component in the structural unit represented by the general formula (III), and the produced polyester has a desired intrinsic viscosity. It can be difficult to do.

The content of the structural unit represented by the general formula (I) and the structural unit represented by the general formula (II) and the content of the general formula (I
Regarding the relative proportion of the content of the structural unit represented by II), the weight percentage of the structural unit represented by the general formula (I) and the structural unit represented by the general formula (II) on the basis of the produced copolymerized polyester is calculated. When the total is represented by Y ↓ 0 (% by weight), and the molar percentage occupied by the structural units represented by the general formula (III) based on the total acid components contained is represented by Z ↓ 0 (mol%), Y ↓ 0 / Z It is preferable that the value of ↓ 0 is in the range of 2 to 40 because a fiber having particularly improved both surface wettability and mechanical performance can be obtained.

The above-mentioned copolymerized polyester is mainly composed of
A dicarboxylic acid unit, a diol unit, a structural unit represented by the general formula (I), a structural unit represented by the general formula (II) and a structural unit represented by the general formula (III) as described above, You may have a structural unit in the quantity which does not lose the effect | action and effect of this invention. Examples of the structural unit which may be optionally included include hydroxycarboxylic acid units such as p-oxybenzoic acid units and p- (β-oxyethoxy) benzoic acid units; glycerin units and trimethylo- units.
Tripropane units such as propane units; tetraole units such as pentaerythritol units; trimellitic acid units;
Examples include tricarboxylic acid units such as trimesic acid units; tetracarboxylic acid units such as pyromellitic acid units.

It is preferable that the copolyester is dissolved in a mixed solvent of phenol and tetrachloroethane (weight ratio 1: 1) and the intrinsic viscosity measured at 30 ° C. is 0.5 dl / g or more. If the intrinsic viscosity of the copolyester is less than 0.5 dl / g, the yarn breakage during melt spinning will be remarkable, while if the intrinsic viscosity is too large, the melt viscosity will be too high and the spinnability will be poor. Therefore, the intrinsic viscosity of the copolyester is preferably in the range of 0.5 to 1.0 dl / g from the viewpoint of reducing troubles in the fiberizing process.

The above-mentioned copolyester can be produced according to a known method. For example, when a polyester is produced by polycondensing a dicarboxylic acid or an ester-forming derivative thereof with a diol or an ester-forming derivative thereof, a side chain type polyoxyalkylene group-containing comonomer is used as another monomer. , A main chain type polyoxyalkylene group-containing comonomer and metal sulfonate
A desired amount of each of the comonomers containing a tomo group is added to the reaction system at any stage until the polycondensation reaction is completed, and the intrinsic viscosity is 0.5 dl / g or more, preferably 0.5 to 1.0 dl.
It is produced by carrying out a polycondensation reaction to a desired value within the range of / g.

As the dicarboxylic acid, terephthalic acid,
Examples thereof include aromatic dicarboxylic acids such as isophthalic acid, naphthalenedicarboxylic acid, and diphenyldicarboxylic acid; alicyclic dicarboxylic acids such as 1,4-cyclohexanedicarboxylic acid; aliphatic dicarboxylic acids such as sebacic acid and adipic acid. Examples of the ester-forming derivative of dicarboxylic acid include lower alkyl esters such as dicarboxylic acid dimethyl ester and diethyl ester exemplified above. Further, as the above-mentioned diol, ethylene glycol, 1,3
-Propanediol, 1,4-butanediol, 1,5
-Pentanediol, 1,6-hexanediol, neopentyl glycol, 3-methyl-1,5-pentanediol, 1,9-nonanediol, 2-methyl-1,8
-Aliphatic diol such as octane diol; Alicyclic diol such as 1,4-cyclohexane dimethanol; 2,2-
Bis (4-hydroxyphenyl) propane, 4,4'-
Aromatic diols such as sulfonylbisphenol and the like can be mentioned. Examples of the ester-forming derivative of diol include ethylene oxide.

The above side chain type polyoxyalkylene group-containing comonomer provides the structural unit represented by the general formula (I), and examples thereof include polyoxyethylene glycol-methyl-glycidyl ether and polyoxyethylene glyco. -Methyl-2,3-dihydroxypropyl ether, polyoxyethylene glycol-ethyl-glycidyl ether, polyoxyethylene glycol-ethyl-
2,3-dihydroxypropyl ether, polyoxyethylene glycol-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, 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 Ter, polyoxyethylene glycol-nonylphenyl-2,3-dihydroxypropyl ether, polyoxyethylene glycol-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 copolymer n-propyl-glycidyl ether, polyoxyethylene glycol / polyoxypropylene glycol copolymer n It is possible to use one kind or two or more kinds selected from -propyl-2,3-dihydroxypropyl ether and the like.

The above main chain-type polyoxyalkylene group-containing comonomer provides the structural unit represented by the general formula (II). For example, polyoxyethylene glycol,
One kind or two or more kinds can be selected and used from polyoxypropylene glycol, polyoxyethylene glycol / polyoxypropylene glycol copolymer and the like.

Comonomers containing the above metal sulfonate groups
Represents a structural unit represented by the general formula (III), for example, 5-sodium sulfoisophthalic acid, 5-
Sodium sulfoisophthalic acid dimethyl ester, 5-
Sodium sulfoisophthalic acid diethyl ester, 5-
Metal sulfonation such as potassium sulfoisophthalic acid, 5-potassium sulfoisophthalic acid dimethyl ester, 5-potassium sulfoisophthalic acid diethyl ester, 5-lithium sulfoisophthalic acid, 5-lithium sulfoisophthalic acid dimethyl ester, 2-sodium sulfoterephthalic acid Benzenedicarboxylic acid or lower alkyl ester thereof; 4-sodium sulfo-2,7-naphthalenedicarboxylic acid, 4-sodium sulfo-2,6-naphthalenedicarboxylic acid, 4-sodium sulfo-2,6
-Naphthalenedicarboxylic acid dimethyl ester, 6-sodium sulfo-1,4-naphthalenedicarboxylic acid, 5-
Examples thereof include metal sulfonated naphthalenedicarboxylic acids such as sodium sulfo-1,4-naphthalenedicarboxylic acid or lower alkyl esters thereof.

The above-mentioned copolymerized polyester includes known catalysts used for producing ordinary polyesters, for example, zinc compounds such as zinc acetate and zinc carbonate, manganese compounds such as manganese acetate and manganese carbonate, calcium acetate. , Calcium compounds such as calcium carbonate, cobalt compounds such as cobalt acetate and cobalt carbonate, transesterification catalysts such as barium compounds such as barium acetate and barium carbonate; antimony compounds such as antimony oxide, germanium compounds such as germanium acetate, orthotitanic acid Examples thereof include polycondensation catalysts such as tetraisopropyl and potassium potassium oxalate.

The above-mentioned copolyester contains optional additives such as anti-coloring agent, heat-resistant agent, fluorescent bleaching agent, flame retardant, antioxidant, matting agent, coloring agent, and inorganic fine particles, if necessary. It may be.

It is generally known that polyoxyalkylene is easily oxidized by oxygen in the air. Also in the above-mentioned copolyester, the polyoxyalkylene chain portion may be oxidized under high temperature conditions such as polycondensation reaction and melt spinning conditions, which may cause inconveniences such as a decrease in the degree of polymerization and coloring of the fiber. It is preferable to add an antioxidant in order to obtain a fiber having good mechanical performance. Antioxidants can be classified into chain initiation inhibitors, radical chain inhibitors, peroxide decomposers, etc. according to their mechanism of action, but antioxidants classified as radical chain inhibitors are superior in terms of effectiveness. However, a hindered phenol type antioxidant is suitable. The hindered phenolic antioxidant is a phenolic compound having a sterically hindering substituent on both or one of two carbon atoms adjacent to the carbon atom having the phenolic hydroxyl group, Ir
ganox1010 (manufactured by Ciba-Geigy), Irga
nox1330 (manufactured by Ciba-Geigy), Godrit
Commercially available products such as e3114 (manufactured by Goodrich), Syanox (manufactured by American Cyanamid) and the like can be used.

The above-mentioned hindered phenol antioxidants may be used alone or in combination of two or more. Further, it may be used in combination with other antioxidants, and is particularly classified into phosphorus-based antioxidants such as triphenyl phosphite, and peroxide decomposers such as sulfur-based antioxidants such as dilauryldithiopropionate. When used together with the antioxidant, a higher antioxidant effect may be obtained due to the synergistic effect with the hindered phenol type antioxidant.

The amount of the hindered phenol type antioxidant used is 0.2 to the total of the structural units represented by the general formula (I) and the general structural formula (II).
The amount is preferably within the range of 20% by weight,
It is more preferable that the amount be in the range of 0.5 to 10% by weight. If the amount of the hindered phenolic antioxidant used is less than 0.2% by weight, the antioxidant effect of the resulting fiber may be insufficient, whereas if it exceeds 20% by weight, the resulting fiber may be insufficient. The antioxidant effect reaches saturation, no remarkable improvement in effect is observed, and on the contrary, there is a risk of causing troubles such as single yarn breakage in the spinning process, and the mechanical performance of the obtained fiber may deteriorate. Further, the hindered phenol type antioxidant can be added until the polycondensation reaction of the above copolymerized polyester is completed or at any stage after the completion.

The copolyester thus obtained (which may be simply referred to as a polymer hereinafter) is then crystallized at a temperature in the range of 130 to 150 ° C. while preventing the polymer from sticking. It is applied and dried so that the water content is 50 ppm or less. The crystallization temperature and the drying temperature are preferably 150 ° C or lower, and 150 ° C.
If it exceeds, the polymer is colored, which causes a problem in the whiteness of the obtained fiber. The crystallized and dried polymer is melt extruded in an extruder by a conventional method,
From a spinneret heated to 70 to 290 ° C., the fiber is spun at a predetermined speed. The obtained tow-shaped fiber is stretched and heat-set in a water bath. The stretching ratio is preferably about 0.75 times the cutting stretching ratio, and heat setting treatment is performed by passing it through warm water of 90 ° C. or higher, dry heat roller of 120 ° C. or higher. The heat-setting treatment is a treatment necessary for fixing the internal strain of the fiber and fixing the molecular structure of the fiber, and is a treatment usually carried out. In the present invention, it is preferable to further carry out the heat setting treatment while carrying out a so-called overfeed in which the take-up speed is subsequently made slower than the supply speed. The copolyester fiber thus obtained has a Young's modulus in water at 20 ° C. of 40 g / denier or less, and a Young's modulus in water at 20 ° C. is air at 20 ° C. and 65% RH. It is 80% or less of the Young's modulus among them, and when such a fiber is used in a non-woven fabric, a non-woven fabric having good hydroentanglement and high strength can be obtained.

The single fineness of the above-mentioned copolyester fiber is preferably 5 denier or less, more preferably 3 denier or less, and further preferably 2 denier or less. The smaller the single fineness, the easier the entanglement due to the water-jet punching treatment.

Further, the above-mentioned copolyester fiber is
By selecting the shape of the base to be used, it is possible to select a circular shape; It may have a hollow fiber, and is not limited to a solid fiber. In particular, the cross section of the fiber is preferably flat because it promotes the effect of water jet punching and improves the entanglement. From the viewpoint that the high surface wettability of the copolyester is effectively reflected on the water absorption and the water retention in the fiber assembly, the specific surface area of the fiber is preferably large. From this viewpoint, the single fineness of the fiber is 5
Denier or less is preferable, and it may be advantageous to have a cross-sectional shape having a recess such as a multi-leaf shape or a T shape. Further, the copolyester fiber in the present invention may be a composite fiber in which the above-mentioned copolyester and other resin are used in combination, so-called core-sheath structure, dorso-ventral structure, etc. The copolymerized polyester of occupies 40% or more, especially 60% or more of the fiber surface,
It is preferable because the effects of the present invention are effectively exhibited. Further, other fibers having excellent water absorption, such as rayon, may be mixed with the above copolyester fiber.

The nonwoven fabric of the present invention preferably contains 10% by weight or more of the above-mentioned copolymerized polyester fiber. 10
If it is less than wt%, a nonwoven fabric having excellent water absorption performance cannot be obtained. The nonwoven fabric of the present invention is obtained as follows. First, as described above, the fiber stretched and heat-fixed is cut,
For example, a staple fiber having a length of 30 to 130 mm is passed through a card or a random web to obtain a fiber web such as a random web, a parallel web or a cross lap web. It is preferable that the fiber web is moved to the next treatment step or sufficiently entangled with the nidle punch method so as not to be deformed in the treatment in the subsequent step. The punch density of the needle punch varies depending on the thickness of the fiber web, but generally, a punch density in the range of 10 to 100 punch / cm ↑ 2 is sufficient. In addition, there is a case where it is not necessary to perform the needle punch with a thin fiber web. A high-pressure jet fluid flow is applied to at least one side of the fiber sheet thus obtained to entangle the fibers.

Water is preferably used as the high-pressure jet fluid flow, and water at room temperature, water heated to about 35 to 80 ° C., or the like can be used. Further, the water pressure is determined by the ease with which the fibers are entangled, but is usually set in the range of 10 to 200 kg / cm ↑ 2.
In the entanglement treatment of fibers with a high-pressure jet fluid flow, the apparent density of the layer on the fiber sheet surface side in contact with the fluid flow is 0.03 g higher than the apparent density of the other surface side or the intermediate layer of the fiber sheet. /
It is preferable to perform the process until the height becomes higher than 3 cm ↑ from the viewpoint of smoothness of the fiber sheet and giving a soft feel to the fiber sheet. For example, a fiber sheet treated on one side with a fluid stream
In this case, the apparent density of the layer on the contact surface side is preferably 0.03 g / cm ↑ 3 or more higher than the apparent density of the layer on the other surface side, and the fiber sheet treated on both sides with a fluid stream is preferable. In both cases, both layers have a density of 0.
It is preferably higher than 03 g / cm 3 or more. In order to impart an apparent density gradient to the fiber sheet as described above, the apparent density of the fiber sheet is preferably 0.13 g / cm ↑ 3 or more, and particularly preferably 0.15 g / cm ↑ 3 or more. The basis weight of the non-woven fabric of the present invention varies depending on the use, for example, 15-40 g / m 2 for sanitary facing materials, wiping fiber sheet, wiping cloth, interlining cloth, sheets, and tape.
30-200g / m ↑ 2 for bull cloth, medical gowns, synthetic leather base cloth, and 5 for civil engineering and industrial materials.
For example, 0 to 2000 g / m ↑ 2.

Further, in the above-mentioned method for producing a fiber sheet, thermal binder fibers having a sheath component of a polymer having a relatively low softening temperature are mixed in the range of 5 to 40% by weight based on the nonwoven fabric. It is also possible to fix the space between the fibers with
It is preferable for applications in which the morphological stability of the gut is required.

The non-woven fabric thus obtained is subjected to a smoothing treatment by bringing the surface in which the fibers are closely entangled into contact with a heated calender, or a heating treatment for embossing treatment, dyeing, printing, etc. The product is then colored by.

A major feature of the non-woven fabric of the present invention is that it has such durability that its excellent water absorption performance hardly deteriorates even after washing treatment. Usually, the polyester fibers are coated with various processing agents, treatment agents, finishing agents, etc. on their surfaces to impart water absorbing performance. For example, polyvinyl alcohol-based treatment agents, polyester ether-based hydrophilic antifouling agents, various nonionic, anionic and cationic hydrophilic oil agents, or a combination of these agents.
Nonwoven fabric composed of fibers coated with these processing agents,
Each of them has some initial water absorption performance, but when subjected to a washing treatment, the performance is extremely lowered. On the other hand, it was confirmed that the nonwoven fabric of the present invention hardly deteriorates in water absorption performance after washing.

The nonwoven fabric of the present invention comprises a sanitary napkin, a diaper, a facing material for sanitary materials such as a breast pad, a wiping fiber sheet, a wiping cloth, an interlining, a padded cotton, clothing,
It is useful for medical supplies such as disposable clothes, sheets, table cloths, covers, bags, and civil engineering / industrial materials.

[0060]

EXAMPLES The present invention will be described in detail below with reference to examples, but the present invention is not limited to these examples. Each physical property value in the examples is a value obtained by measurement according to the following methods.

(1) Intrinsic viscosity [η] (dl / g) of copolyester 0.25 g / dl, 0.5 of polyester in a mixed solvent of phenol and tetrachloroethane (weight ratio 1: 1)
The solution was dissolved at each concentration of 0 g / dl and 1.0 g / dl, and each solution was determined from three types of reduced viscosities measured at a temperature of 30 ° C.

(2) Young's modulus (g / denier) of copolyester fiber Using a tensile tester (Autograph IM-100, manufactured by Shimadzu Corporation), at 20 ° C. in water and 20 ℃, 65
It was measured in the air of% RH and determined from the SS curve.

(3) Suction length L (mm) The water absorption length was measured by the Bayrex method. That is, a single cotton fineness of 2 denier and a cut length of 51 mm is carded,
Random webber is applied to obtain a fiber sheet having an average areal weight of 40 g / m 2 and a fiber sheet is obtained. Next hole diameter 0.25m
Using a high-pressure water jet nozzle in which m nozzles are arranged in a line, a columnar water jet with a water pressure of 30 kg / cm ↑ 2 is jetted,
One side of the fiber sheet on the moving wire mesh support is treated, air-dried, and further dried by an auto dryer at 150 ° C.
A nonwoven fabric for water absorption measurement was prepared by heat treatment for 1 minute. This non-woven fabric for measurement was suspended in a state of being partially immersed in water colored with red ink, and the wicking length after 10 minutes was measured. The wicking length was measured with n = 10 in each of the vertical direction and the horizontal direction of the nonwoven fabric, and the value obtained by adding the average values of the vertical and horizontal directions was defined as the wicking length.

(4) Breaking length of non-woven fabric (kg) After a test piece having a width of 2.5 cm and a length of 10 cm was sampled from the non-woven fabric and the strength of the test piece was measured using the above tensile tester. Then, this strength value was gradually reduced by the unit weight of the test piece to calculate the breaking length.

Examples 1 to 6 Terephthalic acid, 5-sodium sulfoisophthalic acid and ethylene glycol were charged into an esterification reactor in the proportions shown in Table 1, and were heated at 230 ° C. under a pressure of 2.5 kg / cm ↑ 2. The esterification reaction was carried out for 3 hours. Then, the obtained reaction product was transferred to a polycondensator previously heated to 230 ° C.

[0066]

[Chemical 9]

The amount of the side chain type A polyoxyalkylene group-containing compound represented by and the main chain type polyoxyalkylene group containing compound represented by the formula HO- (CH ↓ 2CH ↓ 2O) ↓ 45-H shown in Table 1 1,3,5-tris (4-t-butyl-3-hydroxy-2,6-dimethylbenzyl) in an amount of 5% by weight based on the total amount of these polyoxyalkylene group-containing compounds. -1,3,5-triazine-2,4,6- (1H, 3H, 5H) -trione [American Cyanamid, Syanox 17
90], 350 pp of antimony trioxide to polymer
m and phosphorous acid (20 ppm) were added to adjust the polycondensation reaction system. The temperature of the polycondensation reaction system is 230 ° C to 280 ° C
Then, the temperature was gradually reduced to 0.3 mmHg while the temperature was raised over 45 minutes, and then the melt viscosity of the system at 280 ° C. was 28% of that of polyethylene terephthalate having an intrinsic viscosity of 0.60 dl / g.
By continuing the polycondensation reaction until the melt viscosity at 0 ° C. was approximately matched, the corresponding copolyesters were obtained, and the polyester was crystallized at 150 ° C. under vacuum.

The obtained copolyester was melted and extruded, and spun at a spinning temperature of 285 ° C. to obtain a fiber having a round cross section. This fiber was drawn in a first bath at 75 ° C and a second bath at 90 ° C in a two-stage drawing in a water bath with a draw ratio of 3.0, followed by 2%.
Was heated with a dry heat roller heated to 160 ° C. while adding the over feed, and then a fiber oil agent was added thereto, and after mechanical crimping and drying, a single yarn fineness of 2 denier was applied. To obtain a drawn fiber. The obtained fiber was cut into 51 mm length to obtain staple fiber, and 2 fiber webs having an average basis weight of 60 g / m ↑ 2 produced through a card and a random web were used.
Using a high-pressure water jet nozzle in which a number of nozzles having a hole diameter of 0.25 mm are arranged in a row, a columnar water jet with a water pressure of 30 kg / cm ↑ 2 is jetted to form a fiber sheet on a moving wire mesh support. Fiber sheet is entangled and dried, 12
Heat treatment at 0 ° C gives an apparent density of 0.115g /
A nonwoven fabric having a cm ↑ of 3 and an average basis weight of 40 g / m ↑ 2 was obtained.

The performance of the obtained non-woven fabric was measured, and the results are shown in Table 2. As is clear from Table 2, the non-woven fabric of the present invention had good water absorbency and good processability for forming a non-woven fabric.

Examples 7 and 8 In the same manner as in Example 1, except that the cross-sectional shape of the copolyester fiber was changed to a flat section (Example 7) and a U-shaped section (Example 8) instead of the round section. It was spun and entangled with a high-pressure water stream to obtain a nonwoven fabric. This nonwoven fabric was evaluated and the results are shown in Table 2. In each case, the processability of forming a non-woven fabric was good, and the resulting non-woven fabric had good water absorption.

Examples 9 to 11 In Examples 1, as the side chain type polyoxyalkylene group-containing compounds constituting the copolyester, the corresponding side chain type polyoxyalkylene group containing compounds represented by the following formulas are 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 9:

[Chemical 10] Comonomers used in Example 10:

[Chemical 11] Comonomers used in Example 11:

[Chemical formula 12] The obtained polyester was spun in the same manner as in Example 1,
A non-woven fabric was obtained by entanglement with a high-pressure water stream. This nonwoven fabric was evaluated and the results are shown in Table 2. In each case, the processability of forming a non-woven fabric was good, and the resulting non-woven fabric had good water absorption.

Examples 12 and 13 In Example 1, as the main chain-type polyoxyalkylene group-containing compounds constituting the copolyester, the corresponding main chain-type polyoxyalkylene group-containing compounds represented by the following formulas are shown in Table 1. Corresponding copolyesters were obtained in the same manner except that only the amount shown in 1 was used. Comonomer used in Example 12: HO- (CH ↓ 2CH ↓ 2O) ↓ 20-H Comonomer used in Example 13: HO- (CH ↓ 2CH ↓ 2O) ↓ 70-H The obtained polyester was carried out. Spin as in Example 1,
A non-woven fabric was obtained by entanglement with a high-pressure water stream. This nonwoven fabric was evaluated and the results are shown in Table 2. In each case, the processability of forming a non-woven fabric was good, and the resulting non-woven fabric had good water absorption.

Example 14 In Example 1, the amount of the over feed at the time of heat setting was 2%.
A corresponding copolyester fiber was obtained in the same manner except that the amount was changed to 7%. The polyester fiber obtained was entangled with a high-pressure water stream to obtain a nonwoven fabric. This nonwoven fabric was evaluated and the results are shown in Table 2. The processability of forming a non-woven fabric was good, and the resulting non-woven fabric had good water absorption.

Examples 15 and 16 1.2 denier (Example 15) was used instead of 2 denier for the single yarn fineness of the copolyester fiber in Example 1.
A fiber was obtained in the same manner except that 3.0 denier (Example 16) was used. The polyester fiber obtained was entangled with a high-pressure water stream to obtain a nonwoven fabric. This nonwoven fabric was evaluated and the results are shown in Table 2. The processability of forming a non-woven fabric was good, and the resulting non-woven fabric had good water absorption.

[0075]

[Table 1]

[0076]

[Table 2]

Comparative Example 1 A non-woven fabric was prepared in the same manner as in Example 1 by using polyethylene terephthalate single staple fibers having a single yarn fineness of 2 denier and a cut length of 51 mm, and its water absorption performance was measured. There was almost no sex and the strength was weak.

Comparative Example 2 A copolyester was obtained in the same manner as in Example 1 except that the polyoxyalkylene group-containing compound was not used at all. The obtained polyester was spun in the same manner as in Example 1 and entangled with a high-pressure water stream to obtain a nonwoven fabric. This nonwoven fabric was evaluated and the results are shown in Table 4. The water absorption of the non-woven fabric was at a very low level and the strength was weak.

Comparative Example 3 A copolyester was obtained in the same manner as in Example 1, except that no side chain type polyoxyalkylene group-containing compound was used. The obtained polyester was spun in the same manner as in Example 1 and entangled with a high-pressure water stream to obtain a nonwoven fabric. This nonwoven fabric was evaluated and the results are shown in Table 4. The water absorption of the non-woven fabric was at a very low level and the strength was weak.

Comparative Example 4 A copolymerized polyester was obtained in the same manner as in Example 1, except that the main chain type polyoxyalkylene group-containing compound was not used at all. The obtained polyester was spun in the same manner as in Example 1 and entangled with a high-pressure water stream to obtain a nonwoven fabric. This nonwoven fabric was evaluated and the results are shown in Table 4. The water absorption of the non-woven fabric was at a very low level and the strength was weak.

Comparative Example 5 A copolymerized polyester was obtained in the same manner as in Example 1 except that 5-sodium sulfoisophthalic acid was not used at all. The obtained polyester was spun in the same manner as in Example 1 and entangled with a high-pressure water stream to obtain a nonwoven fabric. This nonwoven fabric was evaluated and the results are shown in Table 4. The water absorption of the non-woven fabric was at a very low level and the strength was weak.

Comparative Example 6 In the drawing treatment of the fiber of Example 1, a first bath at 75 ° C. was used to perform one-stage drawing at a draw ratio of 2.0, and a second bath at 90 ° C. gave a total draw ratio of 3.0. Two-stage drawing was performed so as to double the length, and then staple fibers having a single yarn fineness of 2 denier and a length of 51 mm were obtained without carrying out heat setting of the overfeed.
The Young's modulus of the obtained fiber in water was 58 g / denier, and the strength of the nonwoven fabric obtained by entanglement with a high-pressure water stream in the same manner as in Example 1 was low.

[0083]

[Table 3]

[0084]

[Table 4]

[0085]

EFFECT OF THE INVENTION The nonwoven fabric of the present invention exhibits high surface wettability and water absorption in the form of a fiber aggregate, and the nonwoven fabric strength does not decrease even after treatment such as washing, and the initial performance is maintained for a long time. Can be maintained across. INDUSTRIAL APPLICABILITY The nonwoven fabric of the present invention can be applied to a wide range of applications in the field of non-clothing including the wiping cloth.

Claims (2)

[Claims] 1. Young's modulus in water at 20 ° C. is 40 g
/ Denier or less, and a non-woven fabric containing a hydrophilic polyester synthetic fiber as a main constituent, which has a Young's modulus in water at 20 ° C. of 80% or less of Young's modulus in air at 20 ° C. and 65% RH. .. 2. A hydrophilic polyester-based synthetic fiber is mainly composed of a dicarboxylic acid unit, a diol unit, and a general formula (I): [In the Formula, x and y represent 0 or 1 respectively, Z is a formula -O- (R ↓ 2-O) n ↓ 1-R ↓ 1 (In formula, R ↓ 1 is carbonization of C1-C18. Represents a hydrogen group,
R ↓ 2 represents an alkylene group, and n ↓ 1 represents a monovalent group represented by 10 to 100 representing the average degree of polymerization)], a structural unit represented by the general formula (II) -O- (R ↓ 3-O) n ↓ 2- (wherein R ↓ 3 represents an alkylene group, and n ↓ 2 is a number of 10 to 100 that represents an average degree of polymerization), and a general formula. (III) embedded image (Wherein Ar represents a trivalent aromatic group and M represents a metal atom), and the content of the structural units represented by the general formulas (I) and (II) is Each is 1 to 49% by weight, and the total content of the structural units represented by the general formulas (I) and (II) is 2 to 50%.
%, And the content of the structural unit represented by the general formula (III) is 0.5 to 10 mol% with respect to all acid components constituting the copolymerized polyester. The non-woven fabric according to claim 1.