JPH07173724A - Water-soluble polyvinyl alcohol binder fiber and method for heating and press-adhering the fiber - Google Patents

Abstract

PURPOSE:To provide a water-soluble polyvinyl alcohol fiber capable of heated and press-adhered, especially the fiber having usual handleability, when usually used, but capable of being heated and press-adhered substantially without changing its dimension, when heated and press-adhered. CONSTITUTION:A coaxial mono-core sheath-core type conjugate binder fiber is obtained from a polyvinyl alcohol polymer having a melting point of >=210 deg.C and a water-soluble polymer having a melting point of <210 deg.C as a sheath component and a core component, respectively, by a solution-spinning method, and can be heated and press-adhered by applying a linear pressure of >=3kg/cm or a face pressure of >=5kg/cm<2> to the fiber at 140-240 deg.C.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a water-soluble polyvinyl alcohol (hereinafter abbreviated as PVA) binder fiber, which can be heated without impairing the water solubility of the water-soluble PVA fiber, which has hitherto been difficult. The present invention relates to a PVA-based binder fiber that enables adhesion by pressure bonding and a thermocompression bonding method thereof.

[0002]

2. Description of the Related Art For melt-spinnable polyethylene, polyester, etc., heat-bondable fibers are commercially available. Recently, a core-sheath composite fiber having a core as a high-melting polymer and a sheath as a low-melting polymer has been developed, which makes it possible to suppress shrinkage during heat bonding. Utilizing the merits of simplicity, high speed, and no pollution, the application is expanding more and more.

However, these thermo-adhesive binder fibers have a low adhesive effect to hydrophilic fibers such as PVA type and cellulose type, and cannot be used in applications requiring high strength. Therefore, polymers such as acrylic type, melamine type, and PVA type polymers are used alone or in combination as a chemical adhesive in order to obtain a high strength. For example, when manufacturing a chemical lace base fabric which is essential to be water-soluble, a method of applying or impregnating an aqueous solution of a PVA-based resin to a dry non-woven fabric made of water-soluble vinylon and impregnating and drying is generally performed. However, the aqueous solution causes the water-soluble fibers of the base fabric to swell, and it takes time to dry the polymer, so only low-speed production is possible. If water-soluble thermo-adhesive binder fibers can be developed, high-speed production becomes possible. Further, when the base material for wet wiper is adhered to a cellulose substrate with a hydrophobic heat-adhesive fiber, it is incinerated because a defective product is generated or scraps generated by trimming cannot be collected.
If the heat-adhesive fiber is water-soluble, defective products and scraps can be collected and reused.

However, the conventional heat-adhesive fibers are based on a melt-spinnable hydrophobic polymer, and fibers having other water-soluble and heat-adhesive properties and other physical properties that can be used practically have not been obtained. . A PVA-based polymer, which is a typical example of a water-soluble polymer, has a strong intermolecular interaction due to hydroxyl groups in the molecule, has a melting point close to a thermal decomposition temperature, and usually cannot be melted without thermal decomposition. Unable to obtain sex fibers.

Against this background, even in PVA-based polymers, the melting point and softening point are lowered to enable melt molding by internal plasticization due to copolymerization modification or post-reaction modification and external plasticization due to mixing of a plasticizer, or hot melt. Proposals for use as an adhesive have been made. For example, JP-A-51-87
No. 542, JP-A-51-96831, JP-A-53-5.
In each publication of 0239, a water-soluble and hot-melt PVA-based adhesive is disclosed. However, when an attempt is made to fiberize these hot-melt PVA-based polymers,
In order to lower the viscosity during hot melt and increase the adhesiveness, the polymerization degree of PVA is set as low as 600 or less, and not only low-strength fiber can be obtained, but when it is used as a heat-adhesive fiber, Molecules that were oriented during oxidization are melted and relaxed during heat bonding, so that the fibers are greatly shrunk, and it is difficult to use them practically.

Japanese Patent Publication No. 47-29579 and Japanese Patent Publication No. 47-
In each publication of No. 42050, a fiber obtained by adding an ethylene-vinyl acetate copolymer emulsion to a PVA solution and performing wet spinning has heat sealability and can be used as a binder fiber or a main fiber of paper or a nonwoven fabric. Has been described. However, the polymers added are limited to emulsions of water-insoluble polymers. Water-soluble polymers cannot be emulsions and therefore water-soluble.

Further, Japanese Patent Publication No. 41-6605 and Japanese Patent Publication No. 47-31376 describe that a fiber which can be easily fibrillated is prepared by mixing and spinning a completely saponified PVA and a partially saponified PVA. There is. However, these techniques are aimed at easily fibrillated fibers. As one component, fully saponified PVA having good water resistance is used, and stretching, heat shrinkage and, if necessary, acetalization are carried out. is not. Further, it is difficult to spin PVA having a saponification degree of 85 mol% or less by a dehydration coagulation method using an aqueous sodium Glauber's solution which is a usual spinning method for vinylon carried out in the publication, and a fiber obtained by spinning is obtained. It is practically impossible to add PVA having a saponification degree of 85% or less and mix-spin it, because it adheres hard when trying to remove the sodium sulfate adhering to the surface by washing. Therefore, in the examples, PVA having a saponification degree of 88 mol% or more is limited.

Further, Japanese Patent Publication No. 51-28729 discloses that
PVA, polyacrylonitrile, and acrylonitrile graft polymerization PVA is dissolved in dimethylsulfoxide (hereinafter abbreviated as DMSO), which is a common solvent, and a gel yarn obtained by wet spinning is drawn and beaten to describe a self-adhesive synthetic pulp. However, water-soluble fibers cannot be obtained.

Further, in JP-A-52-5318, a low polymerization degree and a low saponification degree PVA and a polymer having a fiber-forming ability are mixed or composite-spun and washed with water to obtain a low polymerization degree and a low saponification degree. It has been proposed to produce ultrafine fibers by removing the degree of chemical conversion PVA, but the polymer having fiber-forming ability is a water-insoluble polymer that is not affected by the water washing treatment, and water-soluble fibers cannot be obtained.

Further, Japanese Patent Laid-Open No. 1-260017 discloses that
A high-strength water-disintegrating PVA-based composite fiber has been proposed which uses a PVA polymer having a saponification degree of 80 to 95 mol% as a core component and a PVA polymer having a saponification degree of 96 mol% or more as a sheath component. This composite fiber is characterized by having high strength and water-disintegration property, is not aimed at obtaining a binder fiber as in the present invention, and there is no description about thermocompression bonding property.

[0011]

As described above, the appearance of water-soluble PVA binder fibers is strongly desired.
It has not been obtained by conventional techniques. Therefore, an object of the present invention is to obtain a water-soluble thermocompression-bonding PVA-based binder fiber. Another object is to provide a thermocompression bonding method for the fibers.

[0012]

[Means for Solving the Problems] The present inventors have completed the present invention as a result of intensive studies on the above problems. That is, in the present invention, a PVA-based polymer having a melting point of 210 ° C. or higher is a sheath component, a water-soluble polymer having a melting point of less than 210 ° C. is a core component, and a core / sheath ratio is 80/20 to 3
A water-soluble PV which is a 0/70 concentric single-core sheath-fiber composite fiber and which can be bonded by thermocompression bonding.
A water-soluble PVA-based binder fiber which is an A-based binder fiber and is further thermocompression bonded under the conditions of a temperature of 140 to 240 ° C. and a linear pressure of 3 kg / cm or more or a surface pressure of 5 kg / cm ² or more. This is a thermocompression bonding method for binder fibers. In the present invention, a PVA polymer having a melting point of 210 ° C. or higher is used as the sheath component. When the melting point of the PVA-based polymer of the sheath component is less than 210 ° C., the heat resistance of the fiber of the present invention,
The handling property under high humidity is insufficient, and a fiber that can be used practically cannot be obtained. It is further preferable that the sheath component PVA-based polymer has a melting point of 215 ° C. or higher. Although there is no particular limitation on the upper limit of the melting point of the sheath component polymer, the melting point is preferably 235 ° C. or lower from the viewpoint of hot water solubility and thermocompression bonding property, and when the melting point is 225 ° C. or lower, the water dissolution temperature decreases. It may be preferable.

Specific examples of the PVA polymer of the sheath component include a polymerization degree of 500 to 24,000 and a saponification degree of 94 to.
Highly saponified PVA of 100 mol%. Polymerization degree is 15
00-4000, saponification degree 95.0-99.5 mol%
Is more preferable in terms of hot water solubility and thermocompression bonding property. In addition, ethylene, allyl alcohol, itaconic acid, acrylic acid, maleic anhydride and ring-opened products thereof, arylsulfonic acid, fatty acid vinyl esters having 4 or more carbon atoms such as vinyl pivalate, vinylpyrrolidone and a part of the above ionic groups. In addition, PVA modified with a modification unit such as a neutralized product is also included. The amount of denaturing unit is 2 mol%
Less, preferably 0.1 to 1.5 mol%. The method of introducing the modifying unit is not particularly limited, whether it is copolymerization or a post reaction. The distribution of the denaturing unit is not limited to random or block. When distributed in blocks, the crystallization-inhibiting effect is small, and the high melting point can be maintained even if it is modified more than randomly. By using a high melting point polymer for the outermost layer of the fiber, it becomes possible to prevent sticking in the fiber manufacturing process. Further, by using a high melting point PVA polymer having a high degree of saponification as a sheath component, it is possible to obtain a performance close to that of a single fiber having a high melting point.

As the core component of the composite binder fiber of the present invention, a water-soluble polymer having a melting point or a fusion temperature of less than 210 ° C. is used. When the melting point or the fusion temperature of the core component polymer is 210 ° C. or higher, the thermocompression bonding temperature becomes too high, and the orientation and crystallinity of the PVA polymer of the sheath component are easily broken during thermocompression bonding, which is not preferable. Even if the water-soluble amorphous polymer does not have a melting point, when the amorphous polymer chip is heated to a predetermined temperature and a pressure of 0.1 kg / cm ² is applied for 10 minutes, the chips will fuse together. When the temperature is the fusion temperature, the water-soluble amorphous polymer having a fusion temperature of less than 210 ° C. is included in the water-soluble polymer of the present invention and can be effectively used as the core component water-soluble polymer. The melting point of the core component water-soluble polymer or the fusing temperature (hereinafter this temperature is also included in the term "melting point") is more preferably 200 ° C or lower, and further preferably 190 ° C or lower.
Furthermore, if the melting point difference between the sheath component and the core component is 20 ° C. or more,
This is preferable because the change in fiber dimensions during thermocompression bonding is reduced. In particular, when the melting point difference is 30 ° C. or more, the dimensional change of the fiber at the time of thermocompression bonding becomes small, and the high orientation and high crystallinity of the sheath component polymer are easily maintained, which is a further preferable embodiment. Most preferably, the melting point difference is 40 ° C. or higher. Since a water-soluble polymer having a melting point of less than 210 ° C. has low orientation and low crystallinity, if the low-melting point polymer is present on the outermost surface of the fiber, it easily adheres to the fiber during the fiber manufacturing process or when the fiber is left under high humidity, which is inconvenient. is there.

Specific examples of the water-soluble polymer having a melting point of less than 210 ° C. in the present invention include low saponification degree PVA, highly ionic group-modified PVA, highly modified carboxymethyl cellulose and other cellulose derivatives, alginic acid and its neutralized products, and chitosan. And natural polymers, polyvinylpyrrolidone and other water-soluble polymers, modified acrylic polymers and the like. Above all, in terms of handleability (especially in high humidity), adhesiveness, performance reproducibility (stability), and cost, the saponification degree is 50 to 9
2 mol%, low degree of saponification PVA with a degree of polymerization of 50 to 4000, allyl alcohol, acrylic acid, methacrylic acid, itaconic acid, maleic anhydride and ring-opened products thereof, arylsulfonic acid, vinylpyrrolidone and ionic groups thereof PVA modified by 1 mol% to 10 mol% with a modification unit partially or wholly neutralized is preferable. There is no particular limitation on the method of introducing the modifying unit, either by copolymerization or post-reaction. The distribution of the denaturing units is random or block without any special limitation. When the degree of saponification is 65 mol% or less, the water solubility at high temperature is particularly lowered, so a PVA-based polymer combined with a small amount of modification in the above modification unit is useful as a core component of the binder fiber of the present invention. There is no particular limitation on the degree of polymerization of the core component polymer, but the core component does not need to contribute to the fiber strength, and since it is important to contribute to the adhesiveness, a low degree of polymerization with good fluidity during thermocompression bonding, For example, 100 to 1000 is preferable.

The composite binder fiber of the present invention is a concentric single-core-sheath composite fiber, that is, a fiber cross-sectional shape in a direction perpendicular to the fiber axis is a circle (core component) in which the center points of the core component and the sheath component are almost the same. And a composite fiber having a donut shape (sheath component) or a shape close thereto. If it is eccentric or if it has two or more multi-core sheaths, the structure of the nozzle block will become extremely complicated and it will be difficult to install, and sufficient consideration must be given to cleaning and maintenance of the nozzle parts. The control range is narrow, and minute changes easily affect processability and quality. Therefore, there is a problem that reproducibility is difficult to obtain. FIG. 1 shows an example of a typical cross-sectional shape of the fiber of the present invention. In the figure, a is a core component and b is a sheath component.

The core component / sheath component ratio of the composite binder fiber of the present invention is in the range of 80/20 to 30/70 by weight. When the content of the high melting point PVA-based polymer in the sheath component is less than 20%, a stable core-sheath composite binder fiber cannot be obtained. On the other hand, if the low-melting point water-soluble polymer is less than 30%, thermocompression bonding performance that can be practically used cannot be obtained. A core / sheath ratio of 60/40 to 40/6 due to the balance between strength and thermocompression bonding
It is more preferably 0. The bonding mechanism of the composite binder fiber of the present invention is such that the high melting point PVA-based polymer phase forming the outermost surface is broken during thermocompression bonding and the low melting point polymer of the core component is extruded onto the outermost surface of the fiber, thereby ensuring thermocompression bonding property. Therefore, it is presumed that it is preferable that the closest distance between the outermost surface of the fiber and the core portion is short because it is easy to break, and in the concentric single core-core sheath composite fiber like the binder fiber of the present invention, the outermost surface of the fiber and the core are Eccentricity is to shorten the closest distance to the part,
It is more difficult than multi-core or blend spinning, but it is important to make fine denier and to make the thermocompression bonding conditions shiva.
Therefore, the fiber of the present invention preferably has a range of 0.4 to 4 denier. If it is less than 0.4 denier, it is difficult to manufacture due to the structure of the nozzle, and if it exceeds 4 denier, it tends to be insufficient in terms of thermocompression bonding property and the texture becomes hard, which is preferable for delicate lace such as chemical lace. Absent. From the balance of spinnability and thermocompression bonding property, 1 to 3 denier is more preferable.

As described above, in the fiber of the present invention, in contrast to the conventional core-sheath composite heat-adhesive fiber in the hydrophobic polymer in which the core is the high melting point polymer and the sheath is the low melting point polymer, the sheath component is High melting point polymer, core component low melting point polymer, usually high orientation, high crystallinity high melting point PVA
The high-melting point low-melting water-soluble polymer that exhibits excellent fiber performance due to the base polymer, breaks the high-melting point PVA-based polymer phase of the fiber outermost layer during thermocompression bonding (applying high temperature and high pressure), and forms the core component. The thermocompression bonding property is ensured by being extruded onto the fiber surface and adhering to the water-soluble polymer as the core component of another fiber or adhering to the high melting point polymer as the sheath component. Highly oriented and highly crystallized high melting point PVA polymer forms a matrix phase, so the strength and dimensional stability are high even under high humidity even if the core component is a low melting point, low water resistance, low melting point water-soluble polymer. Since the matrix phase is excellent, and the matrix phase is not greatly affected even during thermocompression bonding, the dimensional change is small and high strength can be obtained even after thermocompression bonding.

For thermocompression bonding of the binder fiber of the present invention,
It is necessary to bond the fibers by applying a linear pressure of 3 kg / cm or more or a surface pressure of 5 kg / cm ² or more at a temperature of 140 to 240 ° C. When the temperature is less than 140 ° C., the linear pressure is less than 3 kg / cm, or the surface pressure is less than 5 kg / cm ² , the high melting point PVA polymer phase of the sheath component is not generally broken, and the low melting point water-soluble polymer of the core component is extruded onto the fiber surface. The adhesive strength is insufficient because it does not come out. By heating the high melting point polymer of the sheath component and applying pressure in a softened state, the polymer phase of the sheath component is broken, and the low melting point polymer of the adhesive component can be extruded and adhered. If the thermocompression bonding temperature is too high, the molecular orientation of the sheath component and the crystals may be broken, so the temperature should not be higher than 240 ° C. The appropriate pressure-bonding temperature varies depending on the core / sheath polymer specifications, the distribution state, the applied pressure, etc., but 160 to 230 ° C is preferable, and 170 to 220 ° C is more preferable,
More preferably, it is 180 to 210 ° C. Also, if the applied pressure is too high, it will break the fiber structure of the sheath component,
The fiber strength after thermocompression bonding is reduced, which is not preferable. The linear pressure applied by a thermal calendar roller or the like is preferably 800 kg / cm or less. The linear pressure is more preferably 300 kg / cm or less, further preferably 150 kg / cm or less. Surface pressure by heat press is 1500kg / cm
² or less is preferable. The surface pressure is more preferably 600 kg / cm ² or less, further preferably 300 kg / cm ² or less. Usually, a linear pressure of 8 to 80 kg / cm or a surface pressure of 15 to 150 kg / cm ² is used. The thermocompression bonding time is usually 1 minute or less, but in particular, the binder fiber of the present invention can be thermocompression bonded even for a short time of about 0.01 to 10 seconds. The ability to bond in a short time is an important property of the thermocompression bonding method. In the case of the binder fiber of the present invention, if the thermocompression bonding time is set to 10 minutes or longer, the adhesive force tends to be rather reduced. It is preferably 1 minute or less, more preferably 0.01 to 10 seconds, and most preferably 0.05 to 1 second. The cause of this is unknown, but it is presumed to be related to crystallization of the polymer. For this reason, a linear pressure type thermal calender roll method, which has a shorter treatment time, can be more preferably used for thermocompression bonding than a surface pressure type heat press method, which requires a long treatment time.

Next, a method for producing the binder fiber of the present invention will be described. The PVA-based polymer having a melting point of 210 ° C. or higher, which constitutes the sheath portion of the binder fiber of the present invention, is difficult to melt-spin, and thus the core-sheath composite spinning is performed by a solution spinning method such as a dry method, a wet method, or a dry-wet method. P with a melting point of 210 ° C or higher
A spinning stock solution obtained by dissolving a VA polymer and a water-soluble polymer having a melting point of less than 210 ° C. in each solvent is passed through separate stock solution pipes and gear pumps, and the PVA polymer stock solution having a melting point of 210 ° C. or higher is in the sheath, and the melting point is A water-soluble polymer stock solution of less than 210 ° C. is quantitatively discharged from each core-sheath nozzle through a core-sheath nozzle pack set so as to form a core. On this occasion,
The positions of the core undiluted solution discharge holes are arranged so as to form a concentric core-sheath in the final fiber form after the spinning and drawing. In order to carry out stable core-sheath spinning, it is preferable that the pod stock solution and the core stock solution have substantially the same viscosity.

The viscosity of the spinning dope is 500 to 20000 poise for dry spinning, 50 to 1000 poise for dry and wet spinning, and 5 for wet spinning at a temperature near the nozzle during spinning.
Adjust the polymer concentration and undiluted solution temperature to 200 poise. The solvent for the sheath stock solution and the solvent for the core stock solution do not necessarily have to be the same, but they are preferably the same. Various additives may be added to the spinning dope for other purposes.
For example, an antioxidant, a light stabilizer, an ultraviolet absorber, a pigment for dyeing the fiber, a surfactant for controlling the interfacial tension, an acid or an alkali for adjusting the pH, etc. for preventing the decomposition and deterioration of the polymer.

From both core and sheath liquids, the core / sheath ratio was 8
Each is quantitatively discharged so as to be 0/20 to 30/70. In dry spinning, the solvent is evaporated and hot drawing is performed to wind it. In dry-wet spinning, the mixture is first discharged into an inert gas (for example, the atmosphere) layer, then passed through a solidifying solution to solidify and extract the solvent of the stock solution, wet-draw and dry-heat draw, and wind. In wet spinning, the stock solution is directly discharged from a nozzle into a solidification solution for solidification extraction, wet drawing and dry heat drawing, and wound up.

The solvent used for producing the fiber of the present invention is not particularly limited as long as it is a solvent for the sheath polymer and the core polymer, but is dimethyl sulfoxide (hereinafter D) which is a polar organic solvent.
(Abbreviated as MSO), NN'-dimethylformamide, dimethylacetamide, N-methylpyrrolidone, dimethylimidazolidinone and the like. Above all, low temperature solubility,
DMSO is preferred in terms of corrosiveness, toxicity and uniform solidification. Further, the solidifying liquid has a melting point of 210 which is a sheath polymer.
There is no particular limitation as long as it has a solidifying ability for a PVA-based polymer having a temperature of ℃ or higher, and examples thereof include alcohols such as methyl alcohol and ethyl alcohol, acetone,
Examples include ketones such as methyl ethyl ketone, aliphatic esters such as methyl acetate, and hydrocarbons such as hexane and decalin. Among them, methanol, ethanol and acetone are preferable from the viewpoint of uniform solidification and corrosiveness. Further, a mixed liquid of these solidifying solvent (and solution) and stock solution solvent (and solution) can also be used as the solidifying liquid. It should be noted here that even though these solidified liquids have no solidifying ability for the water-soluble polymer as the core component, even if the core water-soluble polymer is extremely soluble in the solidified liquid, It was surprisingly found that if only the high melting point polymer which is the sheath component has the solidifying ability, it can be used sufficiently satisfactorily.

When a concentrated aqueous solution of Glauber's salt, which has been generally used for spinning PVA, is used for the solidifying bath, the resulting mixture becomes nonuniformly solidified, resulting in a cocoon-shaped cross section and insufficient stretch orientation. Can't get When boric acid is added to the stock solution and solidified in an alkaline dehydration salt bath, the partially saponified PVA is saponified during spinning to raise the melting point,
The water solubility is also reduced, which is not preferable. On the other hand, for alcohols such as methanol and ethanol, ketones such as acetone and methyl ethyl ketone, aliphatic esters such as methyl acetate and ethyl acetate, and high melting point PVA-based polymers that serve as sheath components such as mixed solvents of these and undiluted solvents. On the other hand, when an organic solvent having a solidifying ability is used in the solidifying bath, uniform solidification results in a substantially circular cross section, and sufficient oriented crystallization can be performed by subsequent wet drawing and dry heat drawing. Strength, for example, a strength of 7 g / dr or more can be achieved. The cross-sectional shape of the fiber referred to in the present invention can be observed by using an ordinary optical microscope. In order to obtain a more uniform gel yarn, it is preferable to set the temperature of the solidifying bath to a low temperature of 0 to 10 ° C.

Next, the usefulness of the fiber of the present invention will be explained with respect to a non-woven fabric which is one of the uses. A dry non-woven fabric or a wet non-woven fabric containing at least 30% of the fiber of the present invention is a non-woven fabric which can be heat-bonded by thermocompression bonding at a temperature of 140 to 240 ° C. under a linear pressure of 2 kg / cm or more or a surface pressure of 5 kg / cm ² or more. Becomes The nonwoven fabric containing less than 30% of the fiber of the present invention cannot obtain practical thermocompression bonding under the above thermocompression bonding conditions. In order to further enhance the thermal adhesive force when the nonwoven fabric of the present invention is thermocompression bonded, the content of the fiber of the present invention is preferably 40% or more, and more preferably 50% or more. When the fiber of the present invention is used alone or the fiber of the present invention is mixed with another water-soluble fiber, for example, water-soluble vinylon, a water-soluble and thermocompression-bondable nonwoven fabric is obtained. This non-woven fabric can be bonded by thermocompression bonding when it is formed into a three-dimensional structure such as a bag or a pot. Compared with the conventional molding process using chemical adhesive, it is faster, simpler, and pollution-free.
Since the molding process can be performed in a safe process, it is possible to greatly reduce the molding cost. A major feature of this nonwoven fabric is that a water-soluble three-dimensional structure can be manufactured by molding by thermocompression bonding. Therefore, it can be effectively used for, for example, laundry bags, laundry bags, water-degradable sanitary products, water-degradable toiletry products, seed sheets, seed tapes, fertilizer bags, paper pots, and water-soluble funny goods.

Further, hydrophilic but water-insoluble vinylon fibers, rayon, cupra, polynosic, solvent-based cellulose fibers, cellulose fibers such as cotton, and the like according to the present invention are used.
The non-woven fabric containing 0% or more can be thermocompression bonded, and when molding into a three-dimensional structure, the thermocompression bonding method having the above advantages can be applied as compared with the case where a conventional chemical adhesive is used. is there. Further, a feature of the nonwoven fabric using the fiber of the present invention is that when the thermocompression-bonded three-dimensional structure comes into contact with water or hot water, the adhesive force of the thermocompression bonding portion is lost and the original nonwoven fabric shape is obtained. Further, a non-woven fabric using the fiber of the present invention is bonded by utilizing the thermocompression bonding property of the fiber of the present invention, or is bonded by using a water-soluble binder fiber or a water-soluble chemical adhesive, this is used. When contacted with water or hot water, the three-dimensional structure thermocompression-bonded by thermocompression has a property that even the vinylon fibers and the cellulose fibers constituting the non-woven fabric are separated. Cellulose fibers, for example, have been attracting attention as natural-disintegrating, earth-friendly fibers. However, when a nonwoven fabric containing cellulose fibers is molded into a three-dimensional structure, conventionally, a chemical adhesive is used to prepare an adhesive → A complicated process such as application of a predetermined amount → drying / curing was performed, or bonding was performed by a thermal bonding method using a hydrophobic thermal bonding fiber (in this case, bonding can be performed at high speed, simply and without pollution). , The obtained three-dimensional structure cannot utilize the natural disintegration characteristic of cellulose fiber.)
However, the three-dimensional structure obtained by molding the non-woven fabric of the binder fiber of the present invention by the thermocompression bonding method (heat sealing method) can be easily incorporated into an automated line with high speed, simplicity and no pollution, and can be manufactured. In addition, if the three-dimensional structure such as the obtained paper pot, fertilizer bag, seed sheet, seed tape, and root wrapping material is buried in the soil or left on the ground, it loses its adhesive force due to moisture and rain. , The base material cellulose fibers are naturally disintegrated. Therefore, by using the non-woven fabric using the binder fiber of the present invention, it is possible to produce a three-dimensional structure friendly to the earth at low cost and without pollution.

Further, water-insoluble vinylon, cellulosic fibers such as rayon, polyamide fibers such as nylon-6,
If the binder fiber of the present invention is mixed in an amount of 30% by weight or more with a polyolefin fiber, a polyester fiber or a base fiber material obtained by mixing them, and a non-woven fabric is produced by a thermocompression bonding method using this mixed material, a defective product that occurs when the non-woven fabric is produced The scraps generated by trimming, or the used products are brought into contact with water or hot water to separate the original fiber material, and the base fiber material can be recovered and recycled, and can be recycled. Nonwoven fabrics manufactured by the conventional thermocompression bonding method are extremely rational, but they have the disadvantage that they cannot recover and recycle scraps (damaged paper by the wet method) such as defective products and trimming scraps. By using the binder fiber of the present invention, it has become possible to satisfy both the thermal bonding method and the recovery and reusability.

The definition of the parameter and the measuring method thereof in the present invention are as follows. 1. Melting point Means the temperature at which an endothermic peak is exhibited when 10 mg of a sample polymer is heated under nitrogen at a rate of 20 ° C./min using a differential scanning calorimeter (DSC-20) manufactured by Mettler.

2. Fiber strength In accordance with JIS L-1015, the single fiber strength is 20m.
m, tensile rate 50% / min.

[0031]

The present invention will be described in more detail with reference to the following examples, but the present invention is not limited to these examples. In the examples,% is a value based on weight unless otherwise specified.

Example 1 Polymerization degree of 1710, saponification degree of 96.4 mol% and melting point of 21.
PVA at 8 ° C. and PVA having a polymerization degree of 600 and a saponification degree of 70 mol% and a melting point of 172 ° C. were separately mixed and dissolved in DMSO at 100 ° C. under nitrogen with stirring so as to be 22% and 35%, respectively. These stock solutions were weighed with two gear pumps through separate pipes, and the low melting point PVA solution was used as the core and the high melting point PVA was used.
A core-sheath nozzle pack set so that the solution becomes a sheath is discharged into the atmosphere through a core-sheath nozzle having a hole diameter of 0.15 mmφ and a number of holes of 24, and passed through an air gap of 8 mm, and is composed of 78% methanol and 22% DMSO. Dry-wet spinning was performed in a solidifying solution at ℃. At this time, the core / sheath ratio of the polymer is 50 /
The number of rotations of each gear pump was set to 50, and the core stock solution discharge port position of the core-sheath nozzle was adjusted for each nozzle hole so that the core of all fibers after spin-drawing was in the center. After solidification, the gel yarn is subjected to a wet stretching of 4 times, the residual DMSO in the gel yarn is extracted and washed with methanol, and after oiling and drying, it is subjected to dry heat stretching at a total stretching ratio of 11 times in hot air at 210 ° C. The standard type single core-sheath composite 36d / 24f multifilament was obtained.
The melting point difference between the sheath component and the core component was 48 ° C.

The strength of this filament is 8.1 g / d
The cross section was concentric. In addition, this multifilament is crossed in a cross shape, and the temperature is 220 ° C and the linear pressure is 50 kg.
/ Cm, the treatment time was 1 second or less, and the heat calender roll treatment was applied. When the obtained crossing portion was peeled off by hand, it was confirmed that the crossing portion was adhered. Also, when the thermocompression bonded portion was poured into boiling water, the shape disappeared and the material melted.

Comparative Example 1 In Example 1, only the PVA solution of the sheath component was discharged from a normal circular nozzle and spun and drawn in the same manner as in Example 1,
A 36d / 24f multifilament containing only high melting point PVA was obtained. Single filament strength of this filament is 14.3 g /
It was d. In addition, this multifilament is used in Example 1.
Thermal calender roll treatment was performed under the same thermocompression bonding conditions. When the obtained crossing portion was peeled off by hand, it was peeled off very easily and there was almost no adhesive force.

Comparative Example 2 In Example 1, only the PVA solution of the core component was discharged from an ordinary circular nozzle and spun and drawn in the same manner as in Example 1,
An attempt was made to obtain a 36d / 24f multifilament containing only the high melting point PVA, but the fibers were stuck together and a normal filament could not be obtained.

Example 2 Polymerization degree 1750, saponification degree 97.1 mol%, melting point 2
PVA at 20 ° C., polymerization degree 600, saponification degree 60 mol%,
A modified PVA having a melting point of 161 ° C., which is obtained by copolymerizing sodium arylsulfonate with 0.6 mol%, has a concentration of 19% and 36%, respectively.
So that they were separately dissolved in 90 ° C. DMSO with stirring under nitrogen. These stock solutions were weighed with two gear pumps through separate pipes, passed through a core-sheath nozzle pack in which the low-melting point modified PVA solution was the core and the high-melting point PVA solution was the sheath, and the hole diameter was 0.18 mmφ and the number of holes was 48. From the core-sheath nozzle of 10% consisting of 62% methanol and 38% DMSO
Wet spinning was carried out in a solidifying solution at ℃. At this time, the number of rotations of each gear pump was set so that the core-sheath ratio was 45/55 for the polymer, and the core stock solution discharge port position in the core-sheath nozzle was set so that the core portion was almost in the center in all the fibers after spinning and drawing. Was adjusted for each nozzle hole. After solidification, the gel yarn is subjected to a wet drawing of 5.0 times, and the residual DMSO in the gel yarn is
Was extracted and washed with methanol, oiled and dried, then 20
Dry heat drawing was performed at a total draw ratio of 11 times in 0 ° C. hot air, and 9
A 6d / 48f single-core-sheath composite multifilament was obtained.

The strength of this filament was 7.1 g / d and the cross-sectional shape was concentric. In addition, the multifilaments are crossed to form a cross shape at a temperature of 165 ° C. and a linear pressure of 30 kg /
cm, and the treatment time was 1 second or less. When the obtained crossing portion was peeled off by hand, it was difficult to peel it off, and it was confirmed that thermocompression bonding was performed by calendering. In addition, the intersection after thermocompression bonding is 8
When it was poured into hot water at 0 ° C, it dissolved.

[0038]

Industrial Applicability According to the present invention, a high-melting point high-saponification degree PVA and a low-melting point water-soluble polymer are mixed at a predetermined blending ratio, and the high-melting point PVA polymer is used as a sheath component to form a low-melting point water-soluble polymer. A core-sheath composite fiber in which a core component and a sheath component are concentrically arranged as a core component, and by using such a fiber, a water-soluble thermocompression-bondable binder fiber, which has been difficult in the past, was obtained. This binder fiber has a high melting point and a high saponification degree PVA as a matrix and is present in the sheath component to be highly oriented and highly crystallized, and the dimension is stable even under high humidity, and as a normal fiber in a normal state. It can be handled, but when thermocompression bonded, the sheath component phase is broken, the low melting point polymer of the core component is extruded onto the fiber surface, and the fibers are bonded together. Since the high melting point PVA polymer phase of the sheath component does not melt during thermocompression bonding, there is almost no dimensional change and high strength can be maintained even after thermocompression bonding.

As described above, the present invention is a PVA-based binder fiber having both water solubility and thermocompression bonding property, and when used in the field of non-woven fabrics, since bonding by thermocompression bonding is possible, it is a pollution-free, simple process. It enables high speed production. For example, the production of chemical lace base cloth, which was conventionally produced by applying and drying a PVA-based sizing agent aqueous solution, can be rationalized. In addition, since the non-woven fabrics obtained by the dry method and the wet method have thermocompression bonding properties, heat sealing can be performed when molding into a three-dimensional structure such as a bag-like product, so that the molding process can be efficiently produced. sell. When mixed with hydrophilic materials such as vinylon and rayon to form a non-woven fabric, it can be bonded by thermocompression bonding, and when scraps such as defective products, secondary products, trimming pieces, etc., contact with water or hot water. By doing so, materials such as vinylon and rayon can be collected and reused.

[Brief description of drawings]

1 (a) to 1 (d) are diagrams showing typical examples of the cross-sectional shape of the fiber of the present invention.

[Explanation of symbols]

 a: core component b: sheath component

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Satoru Kobayashi 1621 Sakata, Kurashiki City, Okayama Prefecture, Kuraray Co., Ltd. (72) Shunpei Naramura 1621 Sakata, Kurashiki City, Okayama Prefecture, Kuraray Co., Ltd.

Claims (2)

[Claims] 1. A polyvinyl alcohol-based polymer having a melting point of 210 ° C. or higher is a sheath component, a water-soluble polymer having a melting point of less than 210 ° C. is a core component, and the core / sheath ratio is 80/20 to 30/70. A water-soluble polyvinyl alcohol-based binder fiber that is a concentric single-core sheath-fiber composite fiber. 2. The binder fiber according to claim 1 at a temperature of 14
0 ~ 240 ℃, linear pressure 3kg / cm or more or surface pressure 5kg
A thermocompression bonding method for water-soluble polyvinyl alcohol-based binder fibers, characterized in that thermocompression bonding is performed under a condition of / cm ² or more.