JP2002339152A - Polyvinyl alcohol-based crimped fiber and method for producing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a polyvinyl alcohol (hereinafter referred to as PVA)-based crimped fiber which while maintaining superior hydrophilicity, hygroscopicity, weather resistance, chemical resistance, a high strength, and the like of the PVA-based fiber being strong points of it, has excellent cost performance and an excellent level dyeing property when dyed. SOLUTION: This PVA-based crimped fiber has a uniform structure in the fiber cross-sectional direction and further has a prescribed fine hill-like uneven surface, when the surface is observed with an atomic force microscope at a fusing temperature of >=100 deg.C in water. The fiber is obtained by dissolving the PVA-based polymer in an organic solvent, wet-spinning the prepared spinning rope in a low temperature solidification bath based on an organic solvent having a low water content, drawing the spun fiber in a prescribed ratio, preliminarily heating the drawn fiber at a prescribed temperature and then crimping the fiber.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a proprietary fine hill-shaped unevenness using an inexpensive polymer produced industrially and maintaining the characteristics of polyvinyl alcohol (hereinafter abbreviated as PVA) fibers. The present invention relates to a PVA-based crimped fiber having a surface, excellent in process passability, and capable of obtaining a high-performance spun yarn, cloth, nonwoven fabric, or the like having excellent levelness, and a method for producing the same.

[0002]

2. Description of the Related Art Conventionally, PVA-based fibers have higher strength and elastic modulus than polyamide, polyester, and polyacrylonitrile-based general-purpose fibers, and are excellent in hydrophilicity, water absorption, weather resistance, chemical resistance, and the like. Of course, it is also widely used for clothing and living materials.

[0003] In recent years, ultrahigh-strength, high-Young's modulus fibers have been industrialized by gel-spinning ultrahigh molecular weight raw materials in polyethylene, which is a general-purpose polymer. As with polyethylene, high strength and high Young's modulus fibers by gel spinning have been studied for PVA-based polymers.
9-100710, JP-A-59-130314, JP-A-61-108711, JP-A-4-136213, and the like.
A technique for producing an A-based polymer by an all-organic solvent-based wet cooling gel spinning method has been industrialized under the trade name "Claron K-II". "Claron K-II" mainly has a saponification degree of 9
A water-soluble type using 9.5 mol% or less of PVA is mainly used for process assistants, and a PV having a saponification degree of 99.5 mol% or more is used.
A high-strength, high Young's modulus and water-resistant high-strength type using A is commercially available mainly for use as an industrial material for cement reinforcement.

A high-strength PVA-based crimped fiber having water resistance and a method for producing the same have been proposed in Japanese Patent Application Laid-Open No. 3-27111. The technique is based on a degree of polymerization of 3000 (hereinafter abbreviated as PA). (Example: PA3500 only)
And dry-wet spinning using an effective total draw ratio (T
D) is a high draw of 15 times or more. In the case of this technique, a high draw of 15 times or more is performed, and thus the obtained fiber is certainly 11.5 cN / dte in terms of strength.
x (13 g / dr) or more, 18.1 cN / d in the embodiment
It has a high value of tex (20.5 g / dr),
The spinning method is a dry-wet spinning method, and the leveling properties after dyeing with products tend to be inferior, probably because the surface structure of the fibers is different. Japanese Patent Application Laid-Open No. 3-82836 discloses a PV having a high PA (only the PA2600 is used in the embodiment).
A is dry-wet spun, stretched at a high magnification, and has a single yarn tensile strength of 1
It has been proposed to obtain a spun yarn having excellent cut wound resistance by using a crimped fiber of 1.5 cN / dtex (13 g / dr) or more, but similarly, the leveling property tends to be poor.

Further, Japanese Patent Application Laid-Open No. 4-136213 discloses that all-organic solvent-based wet-cooled gel spinning, stretching at a high magnification, and strength of 1 are mainly aimed at improving the reinforcing property of cement.
A PVA-based synthetic fiber having a fine double uneven surface of 3.2 cN / dtex (15 g / dr) or more has been proposed, but a further improvement in the level of leveling property when dyed is desired. I was Japanese Patent Application Laid-Open No. 2000-343852 discloses that the fiber proposed in Japanese Patent Application Laid-Open No. 4-136213 is crimped to provide a high-strength, high-quality spun yarn and a blanket base fabric. Has been proposed,
The surface and internal structure of the fiber were essentially the same as in the above invention, and were not sufficiently satisfactory in terms of levelness.

[0006]

DISCLOSURE OF THE INVENTION The present invention provides a high-strength PVA fiber which is sufficiently high in strength as a general-purpose fiber, and maintains the excellent characteristics of PVA fiber such as hydrophilicity, weather resistance, heat resistance, and chemical resistance while dyeing. It is intended to obtain fibers having excellent levelness and excellent cost performance.

[0007]

Means for Solving the Problems As a result of pursuing the above-mentioned objects, the present inventors have prepared a spinning solution obtained by dissolving a predetermined PVA-based polymer in an organic solvent in an organic solvent-based low-temperature solidification bath having a predetermined water content or less. A PVA-based crimped fiber obtained by wet spinning, stretching at a predetermined magnification, preheating at a predetermined temperature and then crimping solves the above-mentioned problems, and the main causes are the internal structure of the fiber and a unique surface structure Was found to be derived from

That is, according to the present invention, the degree of polymerization is 1200 to 1200.
It is a crimped fiber made of 5000 PVA, having a uniform structure in the fiber cross-sectional direction, and having an underwater fusing temperature of 100 ° C. or more,
When the fiber surface is observed with an atomic force microscope, the maximum amplitude A of the inclination of the surface unevenness in the fiber cross section direction is 2.5 or less, and the number of times P when the inclination becomes 0 is 10 or less per 1 μm. A PVA-based crimped fiber characterized by the fact that
And as a preferable production method, the degree of polymerization is 1200 to 1200.
5000, a spinning solution in which PVA having a saponification degree of 99 mol% or more is dissolved in an organic solvent is discharged from a nozzle, and wet-cooled gel spinning is performed in an organic solvent-based low-temperature solidifying bath having a water content of 3% or less, and extraction, wet drawing, The spinning tow obtained by drying is stretched by dry heat so that the total draw ratio is 9 to 13 times, and heat-treated if necessary. Further, the drawn and heat-treated tow is crimped after preheating to 100 ° C to 180 ° C. And a method for cutting as necessary.

The fibers of the present invention have a uniform structure in the cross-sectional direction,
A conventionally known spinning method, for example, dry spinning of a spinning solution obtained by dissolving PVA in water, or wet spinning of the spinning solution in an aqueous solution of a dehydrated salt (eg, sodium sulfate) and / or a strong alkali agent (eg, sodium hydroxide) It is not a surface morphology having large and rough irregularities having sharp peaks like PVA fiber obtained by spinning, and is also a conventionally known organic solvent-based dry-wet spinning or organic solvent-based wet spinning. It is not a surface morphology having many ultra-fine irregularities, such as high-strength PVA fiber obtained by highly stretching a raw yarn. In other words, the fiber of the present invention is characterized in that it has a surface morphology having fine undulations in the form of relatively flat hills.

In the fiber of the present invention, the fine surface state of the fiber is important, and it is important to select an accurate observation method that faithfully reproduces the surface state. In a scanning electron microscope generally used for surface observation, usually 0.0
Since it is necessary to apply a metal coating to a thickness of 1 μm or more, it is not possible to accurately represent the fine irregularities which are the characteristics of this fiber. In addition, with a transmission electron microscope, a plastic film replica of the sample is taken, shadowing is performed by metal evaporation, and after carbon is evaporated, a replica obtained by a two-step replica method of dissolving the film replica is observed. The height of the unevenness can be measured only by measuring the length, but the shape such as the inclination cannot be accurately represented. Therefore, in the present invention, the sample was directly observed by an electron microscope using an atomic force microscope (AFM) as described later.

FIG. 1 shows an example of a first-order differential curve obtained by performing AFM observation on the fiber surface according to the present invention and analyzing elevation data among the observation results by a method described later.

The number of times P at which the inclination of the surface irregularities of the fiber of the present invention becomes zero is smaller than that of a conventional high-stretched fiber of an organic solvent-based spinning fiber, and has a P value substantially the same as that of a water-based fiber.
The maximum amplitude A of the surface unevenness is smaller than that of the water-based spun fiber,
It has the same unevenness as the highly drawn fiber of the organic solvent-based spinning, that is, it has the feature that it is a surface morphology with hill-shaped fine unevenness with a relatively uneven, flat, large period . The number of times P at which the inclination of the surface irregularities becomes zero is
Fibers exceeding 10 times per micron such as organic solvent-based spun fibers have a large number of irregularities, and the top is sharp and the tint changes even if the angle is slightly changed. For example, there is a problem that the tint of a dyed product is liable to change during long-term use. On the other hand, on a rough surface having a large unevenness such as a water-based spun fiber having a maximum amplitude A of more than 2.5, the dyed product is irritated and lacks levelness. A
Is preferably 2.0 or less, more preferably 1.5 or less.

The fiber of the present invention has a good water resistance, having an underwater fusing temperature of 100 ° C. or higher as measured by the measurement method described later. If the underwater fusing temperature is lower than 100 ° C., it is inconvenient to be melted in a high-temperature wet process such as dyeing, or to stick to each other during drying after the high-temperature wet process, so that the texture becomes coarse and hard. The underwater fusing temperature is preferably at least 105 ° C, more preferably at least 110 ° C.

The fiber of the present invention is characterized in that, when the fiber cross section is observed with an optical microscope described later, the skin core structure is not seen and the structure is uniform in the fiber cross section direction on a plane perpendicular to the fiber axis direction. The fiber obtained by wet spinning an aqueous PVA solution into a dehydrated aqueous salt solution bath has a non-uniform structure in the fiber cross-sectional direction and has a skin core structure, and the cross section of the fiber obtained even when the hole shape of the spinning nozzle is a perfect circle is a cocoon shape. On the other hand, the fiber of the present invention does not have a skin core structure, and if the hole shape of the spinning nozzle is a normal perfect circle, the fiber cross-sectional shape is almost perfect. If the structure is uniform, the fiber properties tend to be excellent, and in particular, there is no flicker after dyeing and the leveling property is excellent, which is preferable. Further, the fiber of the present invention preferably has no abnormal structure that scatters light, such as a whitened portion or a void, in the fiber axis direction. These abnormal structures deteriorate levelness.

The degree of polymerization of the PVA used in the present invention is 120.
0 to 5000. If the degree of polymerization is less than 1200, only low-strength fibers can be obtained. ,
This is inconvenient because the fiber production cost increases. When the degree of polymerization is from 1500 to 2500, it is particularly preferable in terms of the balance between performance and production cost. Regarding the degree of saponification of PVA, PVA having a degree of saponification of 99 mol% or more is used in order to secure a fusing temperature in water of 100 ° C. or more. In particular, the content is preferably 99.5 mol% or more. When the content is 99 mol% or more, excellent durability and dimensional stability are exhibited even when used under severe conditions.

The PVA-based polymer constituting the fiber of the present invention is not particularly limited as long as it has a vinyl alcohol unit as a main component, and may have other constituent units. Examples of the comonomer that forms such a structural unit include olefins such as ethylene, propylene and butylene, acrylic acid and its salts and acrylic esters such as methyl acrylate, methacrylic acid and its salts, and methyl methacrylate. Methacrylic acid esters, acrylamide, acrylamide derivatives such as N-methylacrylamide, methacrylamide, methacrylamide derivatives such as N-methylol methacrylamide, N-vinylpyrrolidone, N-vinylformamide,
N-vinylamides such as N-vinylacetamide, allyl ethers having a polyalkylene oxide in a side chain,
Examples include vinyl ethers such as methyl vinyl ether, nitriles such as acrylonitrile, vinyl halides such as vinyl chloride, maleic acid and salts thereof, and anhydrides and esters thereof. The method for introducing such a comonomer may be a method by copolymerization or an introduction method by a post-reaction.

Hereinafter, an example of a method for producing the fiber of the present invention will be described. The PVA polymer is mixed and stirred with an organic solvent to dissolve PVA to prepare a spinning dope.
The organic solvent of the spinning dope used in the present invention is not particularly limited as long as it is a solvent capable of obtaining a fiber having a perfect circular structure in a cross-sectional direction by cooling gelation, and for example, dimethyl sulfoxide (hereinafter abbreviated as DMSO). ), Polar solvents such as dimethylacetamide, dimethylformamide and N-methylpyrrolidone; polyhydric alcohols such as glycerin and ethylene glycol; and mixtures of these with swelling metal salts such as rhodanate, lithium chloride, calcium chloride and zinc chloride. And a mixture of these organic solvents. In particular, DMSO has low solubility, low toxicity,
Most preferable in terms of low corrosion.

The concentration of the polymer in the spinning dope varies depending on the composition of the PVA polymer, the degree of polymerization and the solvent.
A range of 0% by weight is common. When a spinning dope is prepared, it is preferable to perform heating while stirring at a predetermined temperature under reduced pressure after replacing with nitrogen, while preventing oxidation, decomposition, cross-linking reaction and the like and suppressing foaming. The temperature of the spinning stock solution at the time of discharge is 50 to 15
In the range of 0 ° C., it is preferable that the stock solution does not gel, decompose or discolor. Of course, depending on the purpose other than the PVA-based polymer and the organic solvent, as long as the effects of the present invention are not impaired, the spinning dope contains an antioxidant, an antifreezing agent, a pH adjuster, a concealing agent, a coloring agent, An additive such as an oil agent may be included. However, 10% of water
The spinning dope containing the above is not preferable because water elutes into the solidification bath during spinning and increases the water content in the solidification bath.

The undiluted spinning solution is discharged from a nozzle, and the
The wet spinning is performed in a solidifying bath having a solidifying ability for A. Although there is no particular limitation on the nozzle to be used, the hole diameter is usually in a range of from 0.1 to 0.1 mm when the bath draft is obtained by dividing the bathing speed by the nozzle portion injection speed.
1.0, usually 0.05-0.5m
mφ is used. The number of holes is preferably several hundred holes to several hundred thousand holes in a fiber tow to which the present invention is suitably applied.
Several thousand to several ten thousand holes are more preferable.

As the solidifying solvent used in the present invention, an organic solvent having a solidifying ability for PVA is used. For example, alcohols such as methanol, ethanol, propanol and butanol; ketones such as acetone, methyl ethyl ketone and methyl isobutyl ketone; fatty acid esters such as methyl acetate and ethyl acetate; aromatics such as benzene and toluene; Organic solvents such as the above mixtures are exemplified. In the crimped fiber of the present invention, the fiber structure must be uniform and the surface of the present invention must be a fine hill-shaped uneven surface. It is fundamentally important to obtain solidified itoshino. For this purpose, among the solidifying solvents, alcohols such as methanol and ethanol, and ketones such as acetone, methyl ethyl ketone and methyl isobutyl ketone are preferable, and it is important that the water in the solidifying bath is low. It is not clear why the solidification bath has a low hill-like uneven surface if the water content of the solidification bath is low. However, if a large amount of water, which is a solvent for PVA, is present in the solidification bath, the PVA cannot be solidified and the spinning is performed. Considering that it becomes impossible, it is presumed that even a relatively small amount of water affects the initial gelling state, slightly changes the surface structure of the gel, and becomes apparent in the case of a specific stretching ratio described later. 3% moisture in the solidification bath
If the ratio exceeds the above, the fine hill-shaped uneven surface of the present invention cannot be obtained even when the stretching ratio is set to a specific ratio as described later. The water content in the solidification bath is preferably 2% or less, more preferably 1.5% or less.

A solidification bath containing only a solidification solvent such as methanol or a solidification bath in which a solid solution solvent such as DMSO described later and a solidification solvent are mixed absorbs moisture in the air when left in the normal atmosphere, and is hard to absorb in a humid summer. -10%, 4-5% even in low humidity winter
Water content in the solidification bath is 3%
In order to maintain the water content below, take special measures such as reducing the water content of gas (for example, air or nitrogen) that comes into contact with the solidification bath to 0.5% or less, or contacting the solidification bath with a dehumidifier to remove water. Must.

When the stock solution solvent is DMSO, methanol is the most preferable solidification solvent in consideration of the distillative separation property from DMSO. In order to uniformly and sufficiently solidify the inside of the fiber, the solidification bath is preferably a mixture of a solidification solvent and a stock solution solvent, and the mixing weight ratio of the solidification solvent / stock solution solvent is 95/5 to 40/60, particularly 90. / 10 to 50/5
0, and most preferably 85/15 to 55/45. Further, by mixing the undiluted solvent with the solidification bath, the solidification ability can be adjusted and the cost for separating and recovering the undiluted solvent and the solidified solvent can be reduced.

The temperature of the solidification bath is set to a low temperature of -15 to 30 ° C. in order to obtain a uniform solidified filament by cooling gelation. When the temperature of the solidification bath is lower than -15 ° C, the solidified itoshino obtained has good gelation uniformity, but has a high cross-linking density due to microcrystals and deteriorates elongation in the subsequent step of drawing, resulting in high-performance fibers. Tends to be difficult to obtain. On the other hand, when the solidification bath temperature exceeds 30 ° C., phase separation predominates over gelation, crosslinks due to microcrystals are reduced, and the draw ratio becomes apparently high, but high-performance fibers are obtained without molecular chain orientation. Tend to be difficult to obtain. When the spinning solution is heated to a high temperature, it is preferable to cool the solidifying bath in order to keep the solidifying bath temperature low. From the viewpoint of uniform solidification and energy saving, the solidification bath temperature is set to -5 to 25C, particularly 0 to 20C, and more preferably 2 to 1C.
It is preferably 8 ° C. The solidification referred to in the present invention means that a spinning dope having fluidity changes to a solid having no fluidity.The solidification is performed without changing the composition of the stock solution, and the solidification is performed by changing the composition of the stock solution. Alternatively, it includes both phase separation.

After the solidified yam obtained as described above is separated from the solidifying bath, the solvent constituting the undiluted spinning solution in the solidified yam is extracted, washed and removed. As the extraction bath, an organic solvent having a solidifying ability is suitably used. Next, wet stretching is performed before or during the extraction step or somewhere before the extraction step and before the drying step, if necessary. From the viewpoint of the mechanical performance of the fiber, the prevention of sticking of the dry yarn, and the generation of fluff, it is preferable to perform the wet stretching at 2.0 to 6.0 times. Stretching magnification X Dry heat stretching magnification, hereinafter T
Abbreviated as D. It is preferable to increase the wet draw ratio within a range that does not cause fluff in order to increase) and to suppress sticking of the shinoshino. To increase the wet draw ratio,
It is also effective to perform wet stretching in two or more stages during the extraction step. The wet stretching ratio in the present invention is a value obtained by dividing the speed of the drying roller by the speed of bathing.

Next, the process is led to a drying step. Prior to drying, an oil agent or the like suitable for the purpose is applied, if necessary, followed by drying to obtain a spun yarn. The drying temperature is preferably 220 ° C. or lower, and multistage drying in which drying is performed with hot air of 160 ° C. or lower in the initial stage of drying, and drying at a high temperature in the latter half is preferable because it is possible to prevent both dry adhesion and high efficiency drying.

It is one of the important points in the method for producing the fiber of the present invention that the thus obtained spun yarn tow is drawn at a relatively low draw ratio of 9 to 13 times in total draw ratio TD. The conventional organic solvent-based spun fiber has a standard to increase the TD as much as possible within a range in which fluff and wound yarn are not generated in order to increase strength. As mentioned above, for example,
The claims relating to the production method of JP-A-3-27111, in which the same organic solvent-based PVA crimped fiber as in the present invention is proposed, state that the effective total draw ratio (TD) is 15 times or more. , A 20-fold embodiment is described.
Similarly, Japanese Patent Application Laid-Open No. 3-82836 discloses a PVA-based spun yarn having excellent cut resistance. In the section of the detailed description of the invention, the raw material PVA fiber of the spun yarn is subjected to dry heat drawing of TD 15 times or more. It is described that it is applied. Further, an organic solvent-based wet-spun fiber having a special fine uneven surface mainly aimed at the field of cement reinforcement has been proposed in JP-A-4-14-1.
No. 36213 discloses the TD1
It is described as 6 times or more, and 19.2 times to 20.5 times in the embodiment.

On the other hand, in the present invention, the hot stretching temperature is 220
The film is stretched in the same temperature range as that of the related art, that is, up to 240 ° C., but the TD is stretched by 9 to 13 times. By setting the water content of the solidification bath to 3% or less and the TD to 13 times or less, the surface shape becomes a unique fine hill-like unevenness as described above, and a fiber excellent in leveling property can be obtained. I found it. If the TD is less than 9 times, the object of the fiber of the present invention cannot be achieved in terms of strength and water resistance. If the TD is more than 13 times, the uneven shape of the surface is out of the range of the present invention, and the dyeing becomes turbid after dyeing, and the leveling property is lowered. At a high TD, whitening due to overdrawing (void generation inside the fiber) and fluff may also be related to a decrease in leveling properties, in addition to a change in the uneven shape of the surface. It is unknown why the solidification bath has a moisture content of 3% or less and a TD of 13 times or less, resulting in a fine hill-like uneven surface. It is presumed to be related. It is also unclear why the fine hill-shaped uneven surface defined in the present invention is excellent in levelness, but the light absorption / scattering state changes at a delicate angle when the outermost surface is acute, While the outermost surface wears and changes with use, it is presumed that if the outermost surface is relatively flat, light absorption and scattering are stable, and furthermore, it is hard to wear and stable even when used. In particular, it is preferable to perform hot stretching so that the TD is 10 to 12 times.

The present inventors initially feared that low TD would impair strength and water resistance and would not be practical. Certainly, the strength is lower than that of high TD fiber, and it is not suitable for reinforcing materials. However, it has a sufficiently high strength compared to natural fibers such as cotton and wool and other synthetic fibers such as polyester and nylon. There is no. It also has a water resistance of 9
Using a high saponification degree PVA of 9 mol% or more,
By performing dry heat stretching of TD 9 times or more at 0 ° C., PV
The A molecular chain is oriented and crystallized, and the fusing temperature in water becomes good at 100 ° C. or higher, and on the contrary, the TD is low. It was found that a fiber having excellent yarn quality was obtained because there was no fiber, no unevenness in the fiber axis direction, and no fluff.

The hot drawing method of the fiber of the present invention is not particularly limited, for example, a non-contact or contact type heater, hot blast stove, radiant stove, oil bath, super steam, etc., but as in the present invention, it is as thick as tens of thousands dtex or more. When the tow is stretched, a hot air circulation system capable of heating the tow more uniformly is preferable. In many cases, it is preferable to perform heat stretching in two or more stages by controlling the temperature in multiple stages. In the case of this multi-stage stretching, the maximum temperature of the stretching furnace is preferably set to 220 to 240 ° C.

After the heat stretching, a heat treatment is applied as necessary, and a post-treatment such as crosslinking of a hydroxyl group is applied as needed.
If necessary, an oil agent suitable for the intended purpose of the present fiber may be applied and then dried.

Next, the obtained hot stretching, heat treatment, post-treatment,
The dried tow to which the oil agent is applied is preheated to 90 to 180 ° C., and a general crimping ratio (for example, 4 to
One of the great features of the method for producing the fiber of the present invention is that it is crimped in a dry state so as to have a degree of crimp (for example, 3 to 15 peaks / 25 mm). Tow preheat temperature is 90
If the temperature is lower than ℃, PVA is not sufficiently plasticized, so that not only good crimps cannot be obtained, but also the crimped portion tends to buckle. If the preheating temperature of the tow exceeds 180 ° C., the fiber will stick when pressed at high pressure during crimping. Preheating temperature is 100 ~
The temperature is more preferably 150 ° C. Since PVA is plasticized with water, for example, in JP-A-3-27111,
It has been proposed to apply a crimp after preheating to 40 to 70 ° C. with hot water, but there is a problem that the wet crimp is easily adhered and must be dried after the crimp, which increases the number of steps by one. Low TD of the present invention
9 for fibers that have been drawn to have unique fine hills
When preheated to 0 to 180 ° C and crimped with a mechanical indentation crimping machine, it can be crimped smoothly due to lower Young's modulus and higher elongation than conventional high TD drawn fiber, so it does not easily buckle and there is no buckling part This is presumed to be one of the causes of excellent levelness.

To preheat the tow to 90-180 ° C.,
Use a heating medium circulation roller whose temperature is controlled to 00 to 200 ° C, a heating roller heated by a heater, a hot plate, a hot air circulation furnace, etc., but heat both sides of the tow with a heat roller or a hot plate with good heat conduction. Is preferred.

Next, the obtained crimped tow is cut by a cutter as required for hanging on a card or spinning. There is no particular limitation on the cut of the crimped tow, and the crimp tow is cut to a length of 10 to 200 mm using a commonly used EC cutter or the like.

Next, in this specification, the degree of polymerization and saponification of PVA, cross-sectional structure, fusing temperature in water, surface observation using an atomic force microscope, and the maximum slope of the surface unevenness in the fiber cross-sectional direction obtained from the data. A method for measuring the amplitude A, the number P of times when the inclination of the surface unevenness becomes zero, the moisture content in the solidification bath, the fiber strength, and the like will be described below.

(1) Degree of polymerization of PVA Calculated from the measured value of intrinsic viscosity [η] of an aqueous solution at 30 ° C. in accordance with JIS K6726. The saponification degree is also JI
According to SK6726, the remaining acetic acid groups of the sample are saponified with sodium hydroxide, the consumed sodium hydroxide is quantified by neutralization titration, and subtracted from 100 to determine the degree of saponification in mol%.

(2) Cross-sectional structure A sample fiber is embedded in paraffin, a thin section is prepared with a microtome, placed on a slide glass, an iodine solution is dropped, and magnified 200 times with an optical microscope. Was observed, and it was determined that the cross-sectional structure was uniform if no skin core structure was observed.

(3) Fusing temperature in water 20 fibers of 5 cm sample fiber (if 5 cm cannot be sampled, sample as long as possible) are sampled and aligned.
A 2.2 mg / dtex load is suspended, immersed in water in a pressurizable transparent container, and the water temperature is raised at 1 ° C./min.
Measure the water temperature at which the fiber is cut and the load falls. The same measurement was repeated five times, and the average value was obtained.

(4) Atomic force microscopy observation and data analysis The maximum amplitude A of the slope of the surface unevenness in the fiber cross-section direction and the number of times the slope becomes 0 P The sample fiber is completely cleaned by removing oil and dirt by Soxhlet extraction or the like. Then, the obtained observation sample fiber was fixed to a sample table with an epoxy adhesive. As an atomic force microscope, DI 3100 manufactured by Digital Instruments was used. The tapping mode was measured by using a single crystal silicon model number NCH manufactured by Nanosensors Co., Ltd. Prior to the sample measurement, a reference sample having a pitch of 10 μm and a step of 180 nm was measured, and it was confirmed that the measurement error of the apparatus was within ± 5%. The observation area of the sample is 5 μm square and the scanning frequency is 1H
z and the scanning angle were 90 degrees. The number of scanning lines was 512. Using the data analysis software attached to the device, the height data in the direction perpendicular to the fiber axis was
II data, and convert the data into commercially available waveform analysis software (IGOR Pro version 3.1, Wav).
eMetrics) was analyzed as follows.

First, a five-pass polynomial smoothing algorithm is applied to remove fine noise from the measured data (this processing reduces the magnitude of the frequency at 20% of the sampling frequency to half), and differentiates the data. did.
In the obtained first derivative curve, the number of times per 1 μm (P) at which the differential value (the slope of the original curve) becomes zero for a portion having a width of 2 μm at the center which is considered to be a relatively smooth portion, and The maximum value of the amplitude corresponding to the slope of the curve (maximum amplitude A) was determined. The same sample was repeatedly measured n = 10 times, and the average value of each of P and A was taken as the value of the sample.

(4) Moisture content in solidification bath According to TCD (thermocouple detector) gas chromatograph,
Using diglyme as an internal standard, the moisture content in the solidification bath was measured in mass% under the following conditions. Column initial temperature and retention time; 70 ° C for 5 minutes Column heating rate; 10 ° C / min Column final temperature and retention time; 200 ° C for 7 minutes Vaporization chamber temperature and detector temperature; 250 ° C and 200 ° C Retention time; Water: About 6.7 minutes, diglyme: about 14 minutes From the peak area ratio of water and diglyme in the solidification bath sample,
The relationship between the peak area ratio and the water content in the bath (% by mass) was determined from a previously determined calibration curve.

(5) Fiber strength According to JIS L1013, fibers conditioned in advance were tested for 4 cm in length, deformed at a rate of 100% / min, and initially loaded at 0.22 c.
Tensile breaking strength was determined under the condition of N / dtex, and an average value of n = 10 or more was determined. Denier was determined by a mass method.

[0042]

EXAMPLES The present invention will be described below in more detail with reference to examples, but the present invention is not limited to these examples.

Example 1 PVA having a degree of polymerization of 1750 and a degree of saponification of 99.9 mol%
Was added to DMSO so as to have a concentration of 20% by mass, and the mixture was heated and dissolved at 95 ° C. under a nitrogen atmosphere. The obtained spinning stock solution is discharged from a nozzle having a hole diameter of 0.08 mm and a number of holes of 25,000, and methanol / DMSO / water at 10 ° C. = 65.0.
/33.6/1.4 in a solidification bath.
The gas portion in contact with the solidification bath was sealed as much as possible so as to have an atmosphere of dry nitrogen having a water content of 0.1% or less, and dry nitrogen was blown into the inside. 0.4% or less was devised.
The obtained solidified itoshino is immersed in a methanol bath to extract DMSO, and perform wet stretching of a total of 4.2 times in multiple stages while extracting to give an oil agent.
It was dried with hot air at 0 ° C. Next, the film was stretched in a hot air oven having a temperature gradient of 215 ° C. and 230 ° C. so that the total stretching ratio TD became 11 times. The obtained 55000 dtex stretched tow was guided to two heating rollers whose temperature was controlled to 160 ° C., and both sides of the tow were preheated and crimped by a press crimping machine. When the temperature of the fiber inside the drawn tow before crimping was measured, it was 110 ° C. The obtained crimped tow was cut into 38 mm to obtain a staple fiber of 2.2 dtex-38 mm.

This staple was treated with methanol / benzene =
Soxhlet extraction was performed with a 1/1 solution for 16 hours to remove oil, and the surface of this sample was subjected to AFM observation by the above-described method to determine the maximum amplitude A and the number of times P. A was 1.5 and P was 7 times / μm. When the sample after Soxhlet extraction was observed with an optical microscope by the above method, no skin core structure was observed. Further, the underwater fusing temperature of this sample was 110 ° C. as measured by the method described above.
The strength of this staple is 10.3 cN / dte
x, elongation was 9.1%.

The staple is subjected to cotton spinning, and
The spun yarn was used as a high-count single yarn, and the spun yarn was plain-woven at a standard of 80 × 65 yarns / inch in warp X weft to obtain a fabric having a basis weight of 190 g / m ² . Desizing this fabric,
Caustic soda 12g / l, hydrosulfite 5g /
1, using a dye bath consisting of 3% of a perylene-based dye, dark blue BO, at a bath ratio of 1:20, at a temperature of 70 ° C. and for a time of 45 hours.
Stained under the conditions of minutes. Next, air oxidation was performed for 15 minutes, followed by washing with water, monogen powder 3 g / l and sodium carbonate 2 g / l.
At 90 ° C. for 10 minutes, washing with hot water, washing with water and drying. The obtained dyed fabric had no unevenness of dye, no color fluctuation, and was excellent in levelness.

Comparative Example 1 Staples were obtained under the same conditions as in Example 1 except that the TD was increased by a factor of 15. However, the stock solution flow rate was increased so that the staple fineness was the same as in Example 1. As in Example 1,
AFM observation of the obtained staples revealed that A was 1.3 and P was 13 times / μm. P is large, and it can be seen that the unevenness of the surface is not a flat hill like the staple of the first embodiment but an acute angle.

When observed with an optical microscope, no skin core structure was observed in the cross-sectional direction, but a part of the whitened portion was observed in the fiber axis direction, and a little fluff was also observed. Furthermore, the underwater fusing temperature of this sample was 119 ° C. as measured by the method described above. The strength of this staple is 1
4.1 cN / dtex, elongation was 5.6%. The staple was spun, woven and dyed in the same manner as in Example 1 to obtain a dyed fabric. This dyed fabric had almost no dyed spots, but exhibited color turbulence and was inferior to the fabric of Example 1.

Comparative Example 2 PVA having the same degree of polymerization of 1750 and saponification degree of 99.9 mol% as in Example 1 was added to DMSO so as to be 22% by mass.
The mixture was heated and dissolved under a nitrogen atmosphere at 105 ° C. The obtained spinning dope is discharged from a nozzle having a hole diameter of 0.12 mm and a number of holes of 250, and is passed through a 15 mm air layer into a solidification bath of methanol / DMSO = 70 / 28.7 / 2. Spun.

The obtained solidified Ishino was immersed in a methanol bath to extract DMSO and, while extracting, subjected to a total of 3.8 times wet stretching in multiple stages to give an oil agent.
It was dried with hot air at 0 ° C and the latter half at 180 ° C. Then 225 ° C,
Total draw ratio TD in a hot blast stove with a temperature gradient of 233 ° C
Was stretched 16 times. 550 dtex obtained
100 filament yarns are bundled into a tow having the same fineness as in Example 1, and the yarn is guided to two heating rollers whose temperature is controlled to 160 ° C. in the same manner as in Example 1, and both sides of the tow are preheated and crimped. It was crimped with a machine. The temperature of the fiber inside the drawn tow before crimping was measured and found to be 105 ° C. The obtained crimped tow was cut into 38 mm, and 2.2 dtex was cut.
A -38 mm staple fiber was obtained.

The staple was deoiled in the same manner as in Example 1. The surface of this sample was observed by AFM using the above-described method, and the maximum amplitude A and the period P were determined. A is 1.4, P is 1
4 times / μm. When the sample after Soxhlet extraction was observed with an optical microscope by the above-described method, no skin core structure was observed in the cross-sectional direction of the fiber, but a very whitened portion was observed in the fiber axis direction. Furthermore, the underwater fusing temperature of this sample was 119 ° C. as measured by the method described above. The staple had a strength of 14.3 cN /
dtex and elongation were 5.3%.

The staple was spun, woven and dyed in the same manner as in Example 1 to obtain a dyed fabric. This fabric had almost no stained spots, but showed color turbulence as in Comparative Example 1 and was inferior to Example 1 in terms of levelness.

Comparative Example 3 Spinning was carried out in the same manner as in Example 1 except that the solidification bath was brought into contact with ordinary atmosphere to freely absorb moisture. Then, the water content in the solidification bath was 5.8%, and the bath composition was methanol / DMSO /
Water = 65.0 / 29.2 / 5.8. The spinning was successfully performed for 3 hours. Extraction, wet drawing, oil application, drying, hot drawing, crimping, and cutting were performed on the obtained gel thread in the same manner as in Example 1 to obtain staple fibers of 2.2 dtex-38 mm.

The staple was deoiled in the same manner as in Example 1, and the surface of the sample was observed by AFM.
And the period P. A was 3.1 and P was 12 times / μm. This staple was spun, woven and dyed in the same manner as in Example 1 to obtain a dyed fabric. This fabric had almost no staining spots, however, as in Comparative Example 1, color flicker was observed, and the fabric was inferior to Example 1 in terms of levelness.

Comparative Examples 4 and 5 A commercially available water-based dry-spun PVA filament, FO- manufactured by Kuraray Co., Ltd., which is a commercially available water-based dry-spun PVA filament, similarly to T-5501 (Comparative Example 3) manufactured by Kuraray Co., Ltd.
1239 (Comparative Example 4) was deoiled, and the surface of this sample was subjected to AFM observation by the above-described method to determine the maximum amplitude A and the period P. T-5501 has A of 3.0 and P of 8 times / μm.
FO-1239 has A of 4.5 and P of 5 times / μ.
m. From this, it was found that the PVA filament of the water-based spinning method not based on the cooling gel spinning method had a rough surface with a sharp unevenness in height.

Example 2 PVA having a degree of polymerization of 2400 and a degree of saponification of 99.8 mol%
Was added to DMSO so that the concentration became 15% by mass, and the mixture was heated and dissolved at 105 ° C. under a nitrogen atmosphere. The obtained spinning dope is discharged from a nozzle having a hole diameter of 0.10 mm and a number of holes of 5,000, and methanol / DMSO / water at 8 ° C. = 65.0 / 3.
The wet spinning was performed in a solidification bath consisting of 4.5 / 0.5. In addition, molecular sheep 4
A column filled with A was provided, the solidification bath was brought into contact with a molecular sheep to remove water, and the device was devised to maintain the water content in the solidification bath at 0.5%. The obtained solidified Ishino is immersed in a methanol bath to extract DMSO, and perform wet stretching of a total of 4.1 times in multiple stages while extracting to give an oil agent.
Drying was performed with hot air at 110 ° C. in the initial stage and 180 ° C. in the latter half. Then 2
The film was stretched in a hot air oven having a temperature gradient of 25 ° C. and 235 ° C. so that the total stretching ratio TD became 12 times. 110 obtained
Five stretched tows of 00 dtex were bundled and guided to two heating rollers whose temperature was controlled at 170 ° C., and both sides of the tow were preheated and crimped by a press crimping machine. The temperature of the fiber inside the drawn tow before crimping was actually measured and found to be 115 ° C. The resulting crimped tow was cut into 38 mm and 2.2d
A tex-38 mm staple fiber was obtained.

This staple was treated with methanol / benzene =
Soxhlet extraction was performed with a 1/1 solution for 16 hours to remove oil, and the surface of this sample was subjected to AFM observation by the above-mentioned method to determine the maximum amplitude A and the period P. A was 1.4 and P was 6 times / μm. When the sample after Soxhlet extraction was observed with an optical microscope by the above method, no skin core structure was observed. Further, the underwater fusing temperature of this sample was measured by the above-mentioned method and found to be 116 ° C.
The staple has a strength of 12.1 cN / dte.
x, elongation was 7.4%.

This staple was subjected to spinning, weaving, and dyeing with olive green B, a benzathlon-based slen dye, in the same manner as in Example 1. The obtained fabric had no spots, no color flicker, and was excellent in levelness.

[0058]

The PVA-based crimped fiber of the present invention has a uniform structure in the cross-sectional direction of the fiber and has a unique fine hill-shaped uneven surface unlike conventional PVA-based fibers, and is excellent in processability and quality. High-quality products, excellent level dyeing, maintaining the characteristics of PVA fiber such as hydrophilicity, moisture absorption, weather resistance, chemical resistance, high strength, etc., as well as clothing, industrial materials, It can be widely and effectively used in the field of living materials.

[Brief description of the drawings]

FIG. 1 shows a first derivative curve obtained by performing AFM observation on the surface of a staple obtained in Example 1 and analyzing high and low data among the observation results by the method of the present invention.

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 4L035 BB03 BB06 BB11 BB15 BB17 BB59 BB66 BB69 BB74 BB79 BB85 BB89 BB91 CC20 DD08 DD19 EE01 EE05 EE08 EE20 FF01 FF10 HH10

Claims (2)

[Claims] 1. A crimped fiber comprising a polyvinyl alcohol-based polymer having a degree of polymerization of 1200 to 5000, having a uniform structure in the cross-sectional direction of the fiber, and having a fusing temperature in water of 100 ° C. or higher. A polyvinyl alcohol characterized in that, when observed with a microscope, the maximum amplitude A of the inclination of the surface unevenness in the fiber cross section direction is 2.5 or less and the number of times P at which the inclination becomes 0 is 10 or less per 1 μm. Based crimped fiber. 2. A polymerization degree of 1200 to 5000 and a saponification degree of 99.
A spinning solution obtained by dissolving at least mol% of a polyvinyl alcohol-based polymer in an organic solvent is discharged from a nozzle and has a water content of
% Or less in an organic solvent-based low-temperature solidification bath, and then subjected to dry heat drawing so that the total drawing ratio is 9 to 13 times. Heat treatment, and then stretch and heat-treat the tow from 100 ° C to 180 ° C.
A method for producing a polyvinyl alcohol-based crimped fiber, comprising crimping after preheating to a temperature of ° C., and cutting as necessary.