JP3345110B2 - Multifilament or staple fiber composed of water-soluble polyvinyl alcohol fiber - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a low-temperature easily water-soluble fiber using a low-melting-point polyvinyl alcohol polymer (hereinafter abbreviated as PVA) and a method for producing the same. For example, it can be suitably used as a material capable of producing a chemical lace base fabric with high efficiency.

[0002]

2. Description of the Related Art Conventionally, as water-soluble fibers soluble in water, PVA fibers, cellulosic fibers such as carboxymethyl cellulose, polyalginic acid fibers, polyalkylene fibers and the like are known. Only PVA-based fibers have the mechanical properties necessary for stably passing through a nonwoven fabric forming step such as spinning and knitting or a knitting step such as spinning or knitting.

As a method for producing PVA-based fibers, a method of dry-spinning a concentrated aqueous solution of PVA (Japanese Patent Publication No. 43-8992, etc.) and a method of wet-spinning an aqueous solution of PVA into an aqueous solution of a dehydrated salt such as sodium sulfate (Japanese Patent Laid-Open Publication No. H10-163). And a method of dry-wet spinning an organic solvent solution of PVA into methanol as a solidification solvent having 1 carbon atom (Japanese Patent Laid-Open No.
No. 229805) is known. In dry spinning of partially saponified PVA comprising only a vinyl acetate unit and a vinyl alcohol unit, it is difficult to convert PVA having a saponification degree of 85 mol% or less into a fiber without firm adhesion between single yarns. JP-A-49-35622 and JP-B-53-53
In Japanese Patent No. 10174, it is proposed to obtain a water-soluble fiber by dry-spinning allyl alcohol or carboxylic acid-modified PVA. However, a heat-bondable PVA-based fiber having a melting point of 205 ° C. or less is hardened between single yarns. You can't get it without wearing it. Therefore, Japanese Patent Application Laid-Open No.
JP-A-45777 proposes to apply a mixture of a PVA solid solvent and a binder to dry-spun fibers, but there is a problem that the feel is hard or the applied material falls off. In addition, the method of wet spinning an aqueous PVA solution into a dehydrated salt bath is such that the salts adhere to the fibers, and if the fibers are washed with water to remove the attached salts, the fibers are firmly fixed between the single yarns. There's a problem. An organic solvent solution of PVA having a degree of saponification of 80 mol% or more is dry-wet spinning in methanol as a solidifying solvent having 1 carbon atom, and then retained in the methanol bath for 5 seconds or more, and then stretched 10 times or more. It has been proposed to obtain water-soluble fibers having a melting point of at least 85 ° C./d (JP-A-1-229805).
Water-soluble fibers with no sticking cannot be obtained with PVA of less than mol%. As a spinning method other than the above, a melt spinning method is also conceivable. However, a water-soluble PVA-based polymer has a small difference in melting point and thermal decomposition temperature, and cannot perform normal spinning.

[0004]

In the prior art, as described above, a low melting point PVA-based polymer cannot be spun without firmly adhering, and therefore a PVA having a melting point of 205 ° C. or less cannot be obtained.
A type fiber is not obtained. For this reason, attempts have been made to obtain a thermal fusibility by attaching a large amount of a low-melting-point solid solvent, but there are problems such as hand hardening and falling off. Therefore, 205
A PVA-based fiber having a melting point of not more than ℃ and having thermal adhesiveness and water-solubility sufficient for practical use has not been obtained, and is capable of responding to high-speed production of nonwoven fabrics such as chemical lace base fabrics. There has been a strong demand for PVA fibers having both water solubility and water solubility.

The present inventors have conducted intensive studies to obtain PVA fibers having both the above-mentioned thermal adhesiveness and water-solubility. After solidification with hydrogen, wet drawing, and extraction using oxygen-containing hydrocarbons having 3 or more carbon atoms, water-soluble PVA fibers having a lower melting point than conventional water-soluble PVA fibers can be obtained without sticking. And found that the present invention was completed. That is, an object of the present invention is to provide a water-soluble PVA-based fiber which has a lower melting point and is easier to thermally bond than conventional water-soluble PVA-based fibers and has no hard adhesion. Another object of the present invention is to provide an industrial production method of such a novel high-performance fiber.

[0006]

The above object of the present invention According to an aspect of the bi
50-95 mol% of nyl alcohol unit, average polymerization
Degree 30-3000, melting point 140-205 in fibrous form
Ability to dissolve PVA-based polymer at ℃
Is dissolved in a stock solution solvent having
Discharges from the nozzle and has the ability to solidify the spinning dope
Alcohols, ketones and fatty acid esters
Dissolve in a stock solution with a compound selected from the group consisting of 3 or more carbon atoms
And the weight composition ratio is 95/5 to 40/60.
Wet spinning to a certain solidification liquid and solidifying, 3 to 8 times wet drawing
Which has a solidifying ability with respect to the spinning dope.
Consists of alcohols, ketones and fatty acid esters
Undiluted solvent with a compound selected from the group and having 3 or more carbon atoms
Water characterized by extracting
Method for producing multifilaments composed of soluble PVA fibers
Method, and cut this multifilament to stay
The problem can be solved by a method for producing a pull fiber .

[0007] The polymers of the present invention have 50-95 mol% of vinyl alcohol units. If it is less than 50 mol%, it is not possible to obtain fibers having the mechanical properties necessary for passing through post-processes such as carding and spinning. When the remaining unit is a so-called partially saponified PVA having only a vinyl acetate unit, if the vinyl alcohol unit is 80 mol% or more (that is, the saponification degree is 80 mol% or more), the obtained fiber usually has a melting point of 20 mol%.
When the temperature exceeds 5 ° C., fibers having excellent heat adhesion cannot be obtained. When a unit other than a vinyl alcohol unit and a vinyl acetate unit is contained (so-called modification of PVA), it differs depending on the type of the modified unit. For example, a unit having a large crystallization inhibiting effect (itaconic acid, maleic anhydride, arylsulfonic acid) Etc.) has a melting point of 205 ° C. even when the vinyl alcohol unit is increased to 95 mol%.
Therefore, it can be suitably used in the present invention.
As units other than the vinyl alcohol unit and the vinyl acetate unit of the present invention, ethylene, allyl alcohol, itaconic acid, acrylic acid, maleic anhydride and its ring-opened product, vinylpyrrolidone, arylsulfonic acid, and some or all of them are neutralized An object is exemplified. The content of these modifying units varies depending on the type of modifying group, but at least 5 mol% is required.

The average degree of polymerization of the polymer used in the present invention is 3
0 to 3000. If the average degree of polymerization is less than 30, fiberization is difficult and the obtained fibers are brittle. Average degree of polymerization is 3
If it exceeds 000, the viscosity at the time of heat melting is high, and it does not spread sufficiently, so that a large bonding area cannot be obtained and the bonding strength is low. The average degree of polymerization is more preferably from 50 to 2,000, even more preferably from 100 to 1,300. The melting point of the fiber of the present invention is 140 to 205 ° C. 140 melting point
It is difficult to obtain a fiber having a temperature lower than ℃ without hardening, and if the melting point exceeds 205 ° C, the thermal adhesiveness of the fiber becomes insufficient.
The melting point of the fiber is more preferably from 150 to 200 ° C, most preferably from 160 to 190 ° C. In the present invention, the melting point is determined by a differential calorimeter DSC- manufactured by Mettler.
20 means a temperature at which an endothermic peak is exhibited at the first temperature rise when 10 mg of a sample is heated from 50 ° C. to 300 ° C. at a rate of 20 ° C./min in a nitrogen atmosphere. The fiber of the present invention has a water dissolution temperature of 5 ° C. or lower, and is also characterized by being easily soluble in water at low temperatures. If the water dissolution temperature exceeds 5 ° C., it is difficult to say that the composition is easily soluble at low temperatures, and the dissolution rate is undesirably low. In the present invention, the water dissolution temperature is 2 mg / dr for the fiber.
Is a temperature at which the load is suspended, immersed in water, and melted when the water is heated at a rate of 2 ° C./min.

The fiber of the present invention has a single yarn denier of 0.1 to 20.
It is characterized in that there is no substantial hard adhesion at dr. It is preferable that the single yarn denier is small for improving the thermal adhesion,
If it is less than 0.1 dr, it is difficult to fiberize without hardening,
Low industrial production efficiency and high production cost. If the single yarn denier exceeds 20 dr, not only a soft texture cannot be obtained, but also a material having poor thermal adhesiveness due to a small specific surface area can be obtained. Single yarn denier is 0.3
More preferably, it is 10 to 10 dr, still more preferably 0.5 to 5 dr, and most preferably 1 to 3 dr. Further, if there is hard adhesion, the denier of a single yarn is substantially increased, so that not only the thermal adhesion is reduced, but also a uniform product cannot be obtained. The term "substantially no sticking" as used in the present invention means that when the multifilament of the present invention is pulled and cut, it has a cut end of 9 mm.
It means that 0% or more separates one by one.

In the present invention, the vinyl alcohol unit was determined by analyzing an NMR spectrum. The average degree of polymerization is JIS-K67 when not ion-modified.
According to JIS-K6726, it was measured from the intrinsic viscosity of a 30 ° C. aqueous solution based on No. 26 or from the intrinsic viscosity of a 1M aqueous NaCl solution when ion-modified.

Next, an example of producing the low-melting water-soluble PVA fiber of the present invention will be described. The fiber of the present invention has a vinyl alcohol unit of 50 to 95 mol% and an average degree of polymerization of 30.
The spinning solution obtained by dissolving the above-mentioned PVA-based polymer having a melting point of 140 to 205 ° C. in a solvent in the form of a fiber in a solvent is used to obtain an acid containing 3 or more carbon atoms having a solidifying ability to the stock solution.
Consisting of an elemental compound and a stock solution and having a weight composition ratio of 95/5
Solidified on solidifying solution is 40/60 performs 3-8 times the wet stretching by the number 3 or more oxygenates in the solvent carbon, then extracted stock solution solvent by number 3 or more oxygenates solvents atoms, Thereafter, it can be manufactured by drying at 120 ° C. or lower.

[0012] Dimethyl sulfoxide (hereinafter abbreviated as DMSO) as a stock solvent of the PVA polymer of the present invention,
Glycerin, ethylene glycol, water, an aqueous solution of zinc chloride or rhodane salt and a mixed solvent thereof can be used, but DMSO, glycerin, ethylene glycol and water are preferred, and DMSO is more preferred. When a low saponification degree PVA polymer having a vinyl acetate unit is used in the present invention, if the alkali of the solution is strong, dissolution, defoaming, saponification reaction occurs during standing, and the melting point of the fiber may increase. The addition of strongly alkaline substances such as sodium hydroxide and caustic soda should be avoided, but the saponification reaction does not occur in a DMSO solution or under weak alkaline conditions such as the addition of sodium acetate. Of course, the acidity may be adjusted by adding an acid. In the case of ionic group-modified PVA such as carboxylic acid and sulfonic acid, the pH may be adjusted with caustic soda for neutralizing ions.
The polymer concentration varies depending on the degree of polymerization and the solvent.
0% is common. Dissolution is preferably performed by stirring the solution under reduced pressure after replacement with nitrogen, from the viewpoint of preventing oxidation, decomposition, and cross-linking reaction and suppressing foaming.

[0013] The obtained spinning stock solution is prepared by using a stock solution comprising an oxygen-containing compound having 3 or more carbon atoms and having a solidifying ability with respect to the stock solution and a stock solution solvent and having a weight composition ratio of 95/5 to 40/60. Solidification is an important point of the fiber manufacturing method of the present invention. The solidification referred to in the present invention means that a fluid spinning dope changes to a solid having no fluidity, and both the gelation, which solidifies without changing the composition of the stock solution, and the solidification, which changes the composition of the stock solution and solidifies, Include. Examples of the oxygen-containing compound having 3 or more carbon atoms having a solidifying ability with respect to the stock solution of the PVA-based polymer include alcohols such as propanol and butanol, ketones such as acetone, methyl ethyl ketone and methyl isobutyl ketone, and acetic acid. Fatty acid esters such as methyl and ethyl acetate are exemplified, and these are used as a mixture of one or more kinds. Among them, acetone and methyl acetate are preferred. Conventionally, methanol and ethanol usually used for organic solvent-based spinning do not have sufficient solidifying ability for low-saponification and / or high-density low-melting-point PVA-based polymers, as in the present invention. I can't get it. For highly saponified and / or low-denatured high-melting-point PVA polymers close to pure PVA, the oxygen-containing compound having 3 or more carbon atoms has an excessively large solidifying ability, so that it is more homogeneous than methanol or ethanol-solidified Ishino. While the solidified yam cannot be obtained and a fiber having a porous fiber structure and satisfactory performance cannot be obtained, when the polymer used in the fiber of the present invention is combined with an oxygen-containing hydrocarbon having 3 or more carbon atoms, the behavior is completely lost. On the other hand, it has been found for the first time that a homogenized solidified yam can be obtained and a fiber having satisfactory performance can be stably obtained. It is estimated that the balance between the solidification ability of the polymer and the solidification ability of the solidification liquid is important. The solidified solution used in the present invention has a weight composition ratio of the oxygen-containing compound having 3 or more carbon atoms and the stock solution solvent of 95/5 to 40/60. It is important that the solidification ability is adjusted by coexisting a stock solution solvent with the solidification liquid. Further, it is preferable to mix the undiluted solvent with the solidified liquid also from the viewpoint of reducing the undiluted solvent and the solidification → recovery cost of the solvent. The temperature of the solidification liquid is not particularly limited, but is usually in the range of -20 to 30 ° C. From the viewpoint of homogenous solidification and energy saving, the solidification liquid temperature is preferably from -10 to 20C, more preferably from -5 to -15C, and from 0 to
It is most preferable that the temperature is 10 ° C. The spinning method of the present invention is not particularly limited, whether wet spinning or dry-wet spinning. Any spinning method can be employed as long as spinning conditions suitable for each spinning method are set, but wet spinning is preferred from the standpoint of suppressing hard adhesion when the nozzle is made porous.

[0014] The obtained solidified itoshino contains oxygen containing 3 or more carbon atoms.
Perform 3 to 8 times wet stretching in the compound . This wet stretching bath may contain a stock solution solvent. It is important to increase the wet draw ratio within a range where there is no fluff in order to suppress the hardening of the yarn. For this reason, it is also effective to raise the temperature of the wet stretching bath to near the boiling point. Next, the wet-stretched shinoshi is brought into contact with a solidifying solvent to extract and remove the stock solvent from the shinoshi. Conventionally, in gelling spinning, it has been proposed to use decalin having 3 or more carbon atoms as a cooling and solidifying solvent. In this case, too, methanol is used as a solvent for extraction and removal of the stock solution solvent. The polymer of the fiber of the present invention swells and hardens even when an organic solvent having 1 carbon atom (for example, methanol) is used in the extract, and an organic solvent having 2 or less carbon atoms cannot be used. Therefore, it is necessary to use an oxygen-containing compound having 3 or more carbon atoms in the extract. Extraction and removal methods include the above acid-containing
The method is used to contact the yarn Shino after stretching dampening containing compound solution, particularly preferably a method for countercurrent contact with the oxygen-containing compound solution and Itoshino. The contact time is preferably at least 15 seconds, particularly preferably at least 20 seconds. In order to increase the extraction rate and improve the extraction, it is preferable that the oxygenated compound solution is heated. Conventionally, after performing wet stretching,
A method of immediately drying without extracting and removing the undiluted solvent is used.However, in the case of a fiber made of a polymer which easily causes sticking between single yarns as in the present invention, drying is performed only by the conventional method as described above. Occasionally, sticking between single yarns will occur. Therefore, in the present invention, the solvent extraction treatment after wet stretching is a very important step.

Next, the itoshino after extraction of the undiluted solvent is dried. In the present invention, it is dried in a gas bath at 120 ° C. or lower. 1
Drying at a temperature exceeding 20 ° C. must be avoided because low-melting fibers such as the fibers of the present invention harden. In addition, it is also effective to adhere a hydrophobic oil such as a mineral oil, a silicone, or a fluorine before drying, or to cause shrinkage to reduce shrinkage stress at the time of drying, to suppress hardening.

If necessary, the dried yarn may be subjected to dry heat drawing and / or dry heat treatment (including dry heat shrinkage). Since the melting point of the present fiber is lower than that of the conventional PVA-based fiber, the temperature of the dry heat drawing and / or the dry heat treatment is 80%.
It is preferably performed at a low temperature of up to 200 ° C.

As described above, the present invention solidifies a spinning dope obtained by dissolving a low-saponification and / or high-modification low-melting-point PVA-based polymer which could not be used as a conventional fiber polymer in a specific solidifying solvent. For the first time, a combination of proper solidification and various measures to prevent hard adhesion will prevent
This is a thermoadhesive and low-temperature easily water-soluble fiber having a melting point of 40 to 205 ° C., which cannot be obtained by conventional wet spinning, dry-wet spinning, or dry spinning.

[0018]

EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples, but the present invention is not limited to these examples.

Example 1 A mixture of 73 mol% of a vinyl alcohol unit and 27 mol% of a vinyl acetate unit, a polymerization degree of 650 and a mixture of PVA having a saponification degree of 73 mol% and DMSO were replaced with nitrogen and replaced with nitrogen under 110 Torr. The mixture was stirred and dissolved at 90 ° C. under reduced pressure for 8 hours, and then defoamed at 90 ° C. at 110 Torr for 8 hours to obtain a DMSO solution containing 40% PVA. This spinning stock solution was kept at 90 ° C. and wet-spun from a nozzle having 100 holes and a hole diameter of 0.12 mmφ into an acetone / DMSO mixed solidified solution having a mixing weight ratio of acetone and DMSO of 85/15 at 2 ° C. Acetone / DMSO = 9
In a mixed solution of 8/2, a 4.2-fold wet stretching is applied, and furthermore, heated acetone and Ishino are brought into countercurrent contact to extract and remove DMSO, and a mineral oil-based oil is applied in an amount of 1% / polymer. Later, 8
It was dried with a hot air drier at 0 ° C. to wind up a 300 dr / 100 f multifilament. Before drying, 5% shrinkage was applied. The saponification degree of the obtained fiber is 74 mol%, which is almost the same as that of the raw material PVA, the melting point is as low as 178 ° C., the water dissolution temperature is 2 ° C. or less, the single yarn denier is 3d, and the single filament is multifilament. Hardness between the yarns was not observed at all, and the yarn was rich in flexibility. Stack the obtained filaments in a cross,
When pressed at 150 ° C. for 1 minute at a high temperature, it was found that they adhered well and had thermal adhesiveness.

Comparative Example 1 Spinning was carried out in the same manner as in Example 1 except that 100% of methanol was used as a solidifying solution. However, solidification was poor, and a normal solidified yarn was not obtained.

Comparative Example 2 Spinning was carried out in the same manner as in Example 1 except that methanol was used instead of acetone to extract and remove the solvent of the stock solution after wet stretching.
Solidified in an acetone solution and wet-drawn to obtain a good wet-drawn yarn, but when immersed in methanol to extract and remove DMSO in the yarn, the methanol swells the yarn and after 1 minute immersion In the case of normal, it became difficult to conduct normal yarn and the yarn was broken.

EXAMPLE 2 A mixture of 78 mol% of a vinyl alcohol unit and 22 mol% of a vinyl acetate unit, a polymerization degree of PVA having a degree of polymerization of 450 and a saponification degree of 78 mol%, and DMSO were mixed and dissolved in the same manner as in Example 1. Defoaming gave a DMSO solution with a PVA of 48%. This spinning stock solution was dry-wet spun from a nozzle having 50 holes and a hole diameter of 0.15 mmφ into a methyl acetate / DMSO mixed solidified solution having a mixing weight ratio of methyl acetate / DMSO of 65/35 at 2 ° C. through an air cap of 1 cm. . The obtained Itoshino is subjected to 6-fold wet stretching in a mixed solution of methyl acetate / DMSO = 90/10, and brought into countercurrent contact with heated methyl acetate to extract and remove DMSO.
3% / After applying the polymer, it was dried at 100 ° C under a nitrogen stream,
A multifilament of 0 dr / 50f was obtained. The melting point of the obtained fiber was 194 ° C, and the water dissolution temperature was 5 ° C or less. The single yarn denier was 2d, and the multifilament did not show any hardening between the single yarns and was rich in flexibility.
Staples obtained by crimping and cutting this fiber and staples of PVA fiber having a saponification degree of 99.9 mol% were mixed in half, and a web obtained by applying a card was heated at 170 ° C.
When a heat calendering treatment of × 50 kg / cm was performed, a heat-bonded nonwoven fabric was obtained.

COMPARATIVE EXAMPLE 3 A mixture of PVA and DMSO having a vinyl alcohol unit of 93 mol% and a vinyl acetate unit of 7 mol%, a polymerization degree of 600 and a saponification degree of 93 mol% was prepared in the same manner as in Example 1. , A 38% PVA DMSO solution was obtained. This spinning stock solution was prepared in the same manner as in Example 1 except that methanol was used in place of acetone in Example 1, and a 300 dr / 10
0f multifilament was obtained. 93 mol% of saponification degree
In the case of PVA, the hard adhesion as in Comparative Examples 1 and 2 did not occur, and the spinning could be performed very smoothly. The obtained fiber had a high melting point of 212 ° C. and a water dissolution temperature of 8 ° C. When this fiber was subjected to a heat bonding test at 150 ° C.,
It did not fuse much.

Example 3 Maleic acid-modified PVA having a polymerization degree of 500 mol% composed of 8 mol% of maleic acid units, 2 mol% of vinyl acetate units and 90 mol% of vinyl alcohol units.
O was mixed and dissolved and defoamed in the same manner as in Example 1 to obtain a 42% PVA DMSO solution. This spinning dope was used in Example 1
In the same manner as in the above, a 300d / 100f multifilament was obtained. The melting point of the obtained fiber was as low as 180 ° C., the water dissolution temperature was 4 ° C. or less, the strength was 1.2 g / dr, and no firm adhesion between single yarns was observed. When the thermal adhesion of this fiber was evaluated at 150 ° C., the adhesion was good.

Comparative Example 4 A maleic acid-modified PVA having a degree of polymerization of 750, comprising 2.5 mol% of a maleic acid unit, 1 mol% of a vinyl acetate unit and 96.5 mol% of a vinyl alcohol unit, was used. The spinning was performed in the same manner as described above. The obtained fiber had a high melting point of 210 ° C. and a water dissolution temperature of 10 ° C. When the thermal adhesion of the obtained fiber was evaluated in the same manner as in Example 3, the thermal adhesion was inferior to that of Example 3.

[0026]

According to the present invention, a low saponification and / or low melting point PVA polymer which could not be conventionally used as a fiber polymer is wet- or dry-wet spinning under specific conditions such as using a specific solidifying solvent. As a result, a heat-adhesive, low-temperature easily water-soluble fiber having a melting point of 140 to 205 ° C. without hard adhesion was obtained. This fiber not only greatly simplifies the manufacturing process by utilizing thermal adhesiveness in the production of chemical lace base fabrics, etc., but also easily dissolves and removes at low temperatures, so that energy can be saved.
Industrial value is great.

──────────────────────────────────────────────────の Continuation of the front page (56) References JP-A-63-50517 (JP, A) JP-A-43-16675 (JP, B1) JP-A-30-6485 (JP, B1) JP-A 32-32 4163 (JP, B1) (58) Fields investigated (Int. Cl. ⁷ , DB name) D01F 6/14 D01F 6/34 D01F 6/50

Claims (2)

(57) [Claims] (1) a vinyl alcohol unit having a content of 50 to 95;
Mol%, average degree of polymerization 30-3000, melting point in fibrous form
Is polyvinyl alcohol-based poly at 140-205 ° C
Dissolved in a stock solution that has the ability to dissolve the polymer.
The spinning solution obtained is discharged from the multi-hole nozzle,
Alcohols and ketones having a solidifying ability with respect to the spinning dope.
Selected from the group consisting of tons and fatty acid esters
Consisting of a compound having 3 or more carbon atoms and a stock solution, and its weight
Wet spinning into a solidified liquid having a composition ratio of 95/5 to 40/60
And wet-stretched 3 to 8 times.
Alcohols and ketones that have the ability to solidify the stock solution
And carbon selected from the group consisting of
Extract the undiluted solvent with several or more compounds,
Water-soluble polyvinyl alcohol characterized by drying under
A method for producing a multifilament composed of polyester fibers. 2. The multifilament according to claim 1,
To produce staple fibers.