JP2002069846A - Polyester fiber structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a modified polyester fiber structure causing little lowering of strength by hydrolysis. SOLUTION: This fiber structure comprises a polyester-based fiber containing >=5 wt.% hydrophilic vinyl monomer polymer containing at least one group selected from amide group, sulfonic acid group and pyrrolidone group.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polyester fiber structure which has a high strength while being improved in moisture absorption due to the inside of the fiber being modified.

[0002]

2. Description of the Related Art Methods for modifying a polyester fiber structure by graft polymerization of a hydrophilic vinyl monomer onto a polyester fiber structure are disclosed in JP-B-59-5126 and JP-A-51-87592. Among such methods, the most frequently studied method is to use a monomer having a carboxyl group as a hydrophilic monomer, graft-polymerize it onto a polyester-based fiber structure, and then displace hydrogen ions of a carboxylic acid to form a metal salt. It is a method. However, in such a method, the polyester fiber becomes alkaline, so that hydrolysis of the polyester progresses with time and the strength is greatly reduced.

[0003]

DISCLOSURE OF THE INVENTION The present invention suppresses a decrease in fiber strength as in the case where a hydrophilic vinyl monomer having a carboxyl group is graft-polymerized, has a strength that can withstand practical use, and has a moisture absorption property. It is an object of the present invention to provide a modified polyester fiber structure having excellent properties.

[0004]

In order to achieve the above object,
The polyester fiber structure of the present invention has the following configuration.

[0005] That is, the polyester fiber structure of the present invention contains at least 5% by weight of a hydrophilic vinyl monomer polymer containing at least one selected from an amide group, a sulfonic acid group and a pyrrolidone group in the fiber. It comprises a polyester fiber. The moisture absorption parameter ΔMR of the polyester fiber structure of the present invention is 2%.
It is desirable that this is the case.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION As the polyester fiber structure in the present invention, a yarn comprising polyester fibers,
Fabrics such as woven fabric, knitted fabric and non-woven fabric can be mentioned. In addition, as long as the effects of the present invention are not impaired, natural fibers such as cotton and wool and other synthetic fibers are blended or mixed with the polyester fiber used in the present invention, twisted, interwoven, interwoven and the like. Can be. In the following description, this polyester fiber structure may be simply referred to as a fiber structure.

The polyester fibers of the present invention include polyester fibers having aromatic polyesters such as polyethylene terephthalate, polypropylene terephthalate and polybutylene terephthalate, and aliphatic polyesters such as polylactic acid and polycaprolactone as basic constituent units. Also included are fibers made of a copolymer obtained by copolymerizing some other component with these, and fibers made of a mixture obtained by blending a small amount of another organic polymer compound with these. Further, the polyester fiber of the present invention may contain inorganic fine particles and low molecular organic compounds as long as the effects of the present invention are not impaired.

In the present invention, a hydrophilic vinyl monomer containing an amide group, a sulfonic acid group or a pyrrolidone group is used. The reason is that the carboxyl group becomes alkaline when metal salted to increase the hygroscopicity with a weak acid, and promotes the hydrolysis of the substrate inside the polyester fiber, whereas these functional groups do not ionize or have a strong acidity. Therefore, this problem can be avoided. Examples of the hydrophilic vinyl monomer used include acrylamide, 2-acrylamido-2-methylpropanesulfonic acid, N-vinylacetamide, styrenesulfonic acid, vinylsulfonic acid, and N-vinylpyrrolidone.

The fiber structure of the present invention is characterized in that it contains a polyester fiber in which a polymer of a hydrophilic vinyl monomer containing such an amide group, a sulfonic acid group and a pyrrolidone group is contained inside the fiber. . Here, that the fiber hydrophilic vinyl monomer polymer is contained inside the polyester fiber means that the fiber is not adhering to the fiber surface but is exhausted inside the fiber cross section. The content of the polyester fiber is desirably 50% or more in order to make use of the characteristics of the polyester fiber such as the easy care property and the variety of cross-sectional shapes.

Conventionally, it has been impossible to introduce only a small amount of a hydrophilic vinyl monomer polymer containing these groups into the interior of the polyester fiber. However, in the present invention, this polymer is used to obtain high hygroscopicity. A feature is that 5% by weight or more is introduced inside the fiber.

In order to confirm that the hydrophilic vinyl monomer polymer is contained in the interior of the fiber, simply measure the weight change of the fiber structure before and after the introduction treatment. In addition, as a more accurate method, the presence or absence of a polymer in the voids between fibers can be confirmed by electron microscopic observation of the cross section of the fiber structure, or the polymer can be dyed by an appropriate method. Methods such as microscopic observation can also be mentioned.

Further, in order to quantify the amount introduced into the interior of the fiber, various chemical analyzes were carried out after confirming that the hydrophilic vinyl polymer polymer was not concentrated on the space between the fibers or on the fiber surface by the above-mentioned method. The amount of the internal hydrophilic vinyl polymer may be determined by a technique. Examples of the chemical analysis method that can be used include, for example, performing solid-state NMR measurement of a fiber structure or IR measurement of a solution of the fiber structure to measure the peak intensity due to the hydrophilic vinyl polymer, Measurement of a chemical species derived from a hydrophilic vinyl polymer by elemental analysis or mass spectrometry is exemplified.

In the present invention, it is desirable that the hydrophilic vinyl monomer polymer is preferably obtained by graft-polymerizing a polymer constituting a polyester fiber. Graft polymerization means that a hydrophilic vinyl monomer polymer is bonded by a chemical bond in a form branched from the polymer constituting the polyester-based fiber. The reason for this is that the hydrophilic vinyl monomer polymer is not exhausted but is chemically bonded, so that the polymer is less likely to fall off from the fiber and has excellent durability.

In the present invention, the moisture absorption parameter ΔMR is a value obtained by subtracting the moisture content at 20 ° C. and 65% RH from the moisture content of the target material at 30 ° C. and 90% RH.
Here, each water content is based on JIS L-1096 6.
Determined by the method described in Item 9. The moisture absorption parameter ΔMR of the fiber structure of the present invention is preferably 2% or more in order to obtain high comfort when worn. Although ΔMR is preferably as large as possible, the effect of the present invention can be sufficiently exhibited if it is about 6%.

The moisture absorption properties of the hydrophilic polymer used in the present invention include, in addition to the above ΔMR, 20 ° C., 65% R
It is desirable that the moisture content (MR) in H is 2 to 6%.

In the present invention, the compulsory test is intended to cause the modified polyester fiber structure to cause deterioration in a short time in the same manner as in the case where the modified polyester fiber structure has been used for a long time. For this purpose, it is possible to use a method in which the fiber structure is left under conditions of high temperature and high humidity, and washing is performed repeatedly. As a compulsory test of the present invention, a method in which the washing is left for one week at 80 ° C. and 65% RH for one week, and then the washing is repeated 10 times, and the cycle is repeated three times.

The component yarn strength of the fiber structure in the present invention refers to the strength of one multifilament constituting a woven or knitted fabric. The constituent yarn strength can be measured by using a tensile tester or the like to measure the strength of the decomposed yarn after decomposing the fibrous structure product. Here, since the characteristics of the yarns constituting the fiber structure vary from part to part, it is desirable to average the measurement results of the decomposed yarns taken from five or more different parts of the fiber structure. In the present invention, the component yarn strength is:
It is desirable that it be 2 g / dtex or more after the forced test.

More preferably, in order to obtain a high-quality product, the component yarn strength after the forced test is 3 g /
It is desirable to be dtex or more. In the present invention, by using an appropriate hydrophilic vinyl monomer, it is possible to greatly suppress the strength reduction after the forced test.

As a method for producing the fiber structure of the present invention, for example, a method in which a hydrophilic vinyl monomer is contained in a supercritical fluid or a fluid similar thereto and the fiber structure is treated therein may be used. In such a method, since the polyester fibers greatly swell, it becomes possible to introduce a large amount of the hydrophilic vinyl monomer polymer which could be introduced into the fiber only in a small amount in the past.

As the supercritical fluid used here, carbon dioxide is most preferable because of the swelling effect of the polyester fiber and the ease of handling. In this medium, a fiber structure, a hydrophilic vinyl monomer and an initiator are contained, and if necessary, an auxiliary agent such as a surfactant is added for treatment.

The treatment temperature may be changed in accordance with the temperature at which the initiator decomposes, but is preferably about 60 to 120 ° C. The processing pressure is desirably about 15 MPa to 40 MPa so that the hydrophilic vinyl monomer is more easily dissolved.

[0022]

EXAMPLES Various measurements in the examples were performed by the following methods. <Measurement of Weight Gain> The sample after treatment in a supercritical fluid with a hydrophilic vinyl monomer was washed alternately three times with methanol and hot water to completely remove the homopolymer, and the weight gain was calculated by the following equation. Was calculated.

Weight increase rate (%) = (W1−W0) / W0 × 100 W0: Absolute dry weight of sample before treatment W1: Absolute dry weight of sample after treatment <Calculation of ΔMR> The ΔMR of the fiber structure to which the molecules were attached was measured by the following method. That is, the sample was put into a weighing bottle, left in a thermo-hygrostat adjusted to 20 ° C. and 65% RH for 24 hours and weighed. Then
It was left for 24 hours in a thermo-hygrostat adjusted to 30 ° C. and 90% RH, and weighed again. Finally, in a dryer at 110 ° C,
After drying for an hour, the absolute dry weight was determined. The difference in the water content was calculated by the following equation.

ΔMR (%) = ((W′−W) / W−
(W ″ −W) / W) × 100 W: Absolute dry weight of sample (g) W ′: Weight of sample at 30 ° C., 90% RH (g) W ″: Sample at 20 ° C., 65% RH <Yarn Strength (Yarn Strength of Yarn Constituting Yarn of Fiber Structure) (Yarn Strength of Yarn)> The tubular knitted sample was disassembled, and five yarns were collected from different portions. The tensile elongation of each yarn was measured with a tensile tester, and the average value was determined. Example 1 A piece of polyester taffeta cloth (cloth after intermediate setting, use of yarn: both warp and weft have a total fineness of 75 denier, 36 multifilaments, woven density: warp 98 x 84 wefts / inch, basis weight:
70 g / m ² ) After filling 50 g into a high-pressure vessel having an internal volume of 500 ml, the temperature was increased to 4 while pouring carbon dioxide into the vessel.
Increased to 0 ° C. Furthermore, carbon dioxide was continuously injected while maintaining the temperature, and the pressure was set to 20 Mpa.

Next, 2 liters of hydrophilic vinyl monomer were added to another 100 ml high pressure container connected to the high pressure container.
-After charging 5.0 g of acrylamide-2-methylpropanesulfonic acid and 0.05 g of benzoyl peroxide which is an organic peroxide as an initiator, the temperature was similarly raised to 40 g.
° C and the pressure were 20 MPa. Thereafter, the valve between the high-pressure container filled with the fibrous structure and the high-pressure container filled with the hydrophilic monomer and the initiator is opened, and the circulation pump connected to the two containers is further activated to remove the hydrophilic monomer and the like. It was introduced into a container filled with a fibrous structure. Then set the temperature to 10
After the temperature was raised to 0 ° C. and the condition was maintained for 30 minutes, carbon dioxide was gradually discharged in the next 30 minutes. Thereafter, this sample was treated in sodium carbonate at 5 g / l at 60 ° C. for 30 minutes to replace the sodium salt.

The weight increase rate of the sample after this treatment and ΔM
Table 1 shows the measurement results of R. When the cross section of this cloth was observed with an electron microscope, no polymer was observed in the gaps between the fibers. As a result, a polyester fiber structure containing 5% or more of a hydrophilic monomer polymer having an amide group and a sulfonic acid group in the fiber and having a ΔMR of 2% or more was obtained.

After measuring the component yarn strength of the sample, the sample was subjected to a forced test at 80 ° C. and 65%
A process was repeated for three cycles, in which one cycle was performed by leaving to stand at RH for one week and then performing ten times of repeated washing. Thereafter, the strengths of the constituent yarns were measured in the same manner. The results are shown in Table 1. From this, it was confirmed that a polyester fiber structure having a constituent yarn strength of at least 2 g / dtex after the forced test was obtained. Example 2 The amount of 2-acrylamido-2-methylpropanesulfonic acid to be filled was 10.0 g and the amount of benzoyl peroxide was 0.1 g.
The same procedure was performed as in Example 1 except that the amount was changed to 1 g.

The weight increase rate of the sample after this treatment and ΔM
Table 1 shows the measurement results of R. When the cross section of this cloth was observed with an electron microscope, no polymer was observed in the gaps between the fibers. As a result, a polyester fiber structure containing 5% or more of the hydrophilic vinyl monomer polymer in the fiber and having ΔMR of 2% or more was obtained.

Table 1 shows the results of measuring the constituent yarn strength of this sample before and after the forced test. From this, it is confirmed that a polyester fiber structure having a constituent yarn strength of at least 2 g / dtex after the forced test was obtained. Was. Comparative Example 1 0.05 g of benzoyl peroxide was added to 1 g of monochlorobenzene
Then, 5.0 g of 2-acrylamido-2-methylpropanesulfonic acid and 0.1 g of sodium laurylbenzenesulfonate were added thereto, and water was added thereto to prepare an aqueous graft polymerization processing agent. Example 1
100 g of the same polyester taffeta cloth piece as
Heated at ° C for 30 minutes.

The results are shown in Table 1. According to this method, a large amount of polymer could not be introduced into the fiber by this method. Comparative Example 2 The same operation was performed as in Comparative Example 1 except that methacrylic acid was used as the hydrophilic vinyl monomer.

The results are shown in Table 1. In this case, although the weight increase rate and ΔMR were high, the component yarn strength after the forced test was 2 g / dtex or less. Examples 3 and 4 The same procedure as in Example 1 was carried out except that N-vinylacetamide was used as the hydrophilic vinyl monomer.

The results are shown in Table 1. As can be seen from these results, a polyester fiber structure having a high weight increase rate and a high ΔMR and a high component yarn strength after the forced test was obtained by these methods. Examples 5 to 6 The same procedure as in Example 1 was carried out except that styrene sulfonic acid was used as the hydrophilic vinyl monomer.

The results are shown in Table 1. As can be seen from these results, a polyester fiber structure having a high weight increase rate and a high ΔMR and a high component yarn strength after the forced test was obtained by these methods. Examples 7 to 8 The same procedure as in Example 1 was carried out except that N-vinylpyrrolidone was used as the hydrophilic vinyl monomer.

The results are shown in Table 1. As can be seen from these results, a polyester fiber structure having a high weight increase rate and a high ΔMR and a high component yarn strength after the forced test was obtained by these methods.

[0035]

[Table 1]

[0036]

According to the present invention, a modified polyester fiber structure can be obtained without the problem of a decrease in strength due to hydrolysis as in the prior art. This polyester-based fiber structure has high hygroscopicity and has a small texture hardening because the inside of the fiber is modified without attaching a large amount of polymer to the fiber surface.

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 4L031 AA18 AB32 AB33 AB34 BA08 BA33 BA34 DA08 4L033 AA07 AB05 AB06 AB07 AC07 CA23

Claims (4)

[Claims] 1. A fiber comprising a polyester fiber containing at least 5% by weight of a hydrophilic vinyl monomer polymer containing at least one selected from amide group, sulfonic acid group and pyrrolidone group in the fiber. Polyester fiber structure. 2. The fibrous structure according to claim 1, wherein the moisture absorption parameter ΔMR is 2% or more. 3. The fiber structure according to claim 1, wherein said hydrophilic vinyl monomer polymer is obtained by graft polymerization of a polymer constituting a polyester fiber. 4. After standing for 1 week in an atmosphere of 80.degree. C. and 65% RH, the operation of repeatedly performing washing 10 times is regarded as one cycle, and this cycle is repeated three times. The fiber structure according to any one of claims 1 to 3, wherein the fiber structure is not less than / dtex.