JPH07138859A - Nonwoven fabric produced by using thermocompression-bonding polyvinl alcohol-based fiber - Google Patents

Abstract

PURPOSE:To provide a nonwoven ground fabric capable of production by efficient processes, suitable for reinforcing use for cement, asphalt, paper, plastic, etc., and excellent in strength, modulus, alkali resistance and heat resistance. CONSTITUTION:This nonwoven ground fabric is produced by blending >=10wt.% high-strength thermocompression-bonding polyvinyl alcohol-based island-sea type fiber in the warp yarns and/or the weft yarns and bonding the intersections formed by putting the weft yarns on the arranged plane of the warp yarns in layers according to the thermocompression-bonding method.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a non-woven fabric using thermocompression-bonding polyvinyl alcohol (hereinafter abbreviated as PVA) fibers, and more specifically, it reinforces a composite molded article such as cement, plastic or paper. The present invention relates to a non-woven fabric (hereinafter referred to as a non-woven base fabric) for producing a non-woven base fabric produced by a thermocompression bonding method using thermocompression-bonding PVA-based fibers.

[0002]

2. Description of the Related Art PVA-based fibers have good strength, elastic modulus, alkali resistance, weather resistance and heat resistance among general-purpose fibers, and are widely used as fibers for industrial materials with excellent cost performance. The non-woven base fabric made of PVA fiber is
Taking advantage of the features of this PVA-based fiber, and further taking advantage of the fact that the PVA-based fiber is far superior to other fibers in terms of adhesion to the object to be reinforced, as a base fabric for reinforcing building materials such as cement and asphalt, It is also used as a reinforcing base fabric for tarpaulins and the like. The reinforcing base cloth is a woven fabric of fibers, a unidirectional prepreg in which the fibers are aligned in parallel in one direction, and a weft yarn that constitutes the base fabric is impregnated with an adhesive and is bonded to a warp yarn. Woven base cloth and warp are impregnated with a small amount of adhesive, and then hydrophobic heat-fusible fibers are used for the weft, and the non-woven base cloth, the warp and the weft are heat-bonded at the intersection with the warp. There is known a non-woven base fabric in which the intersections of the warp yarns and the weft yarns are heat-bonded to each other and bonded to each other via fusion-bonding yarns.

In the woven reinforcing base cloth, the fibers bend up and down at the intersections of the warp yarns and the weft yarns, and the original strength of the fibers in the longitudinal direction cannot be utilized. In particular, fibers having high strength and high elastic modulus have a low elongation, and this tendency is strong. In addition, if the fabric density does not increase with respect to the background, the fabric becomes unsightly and the shape becomes unstable. Therefore, the fabric must be of high density. As the reinforcing base cloth, a coarse material having a coarse mesh is desired from the viewpoint of the impregnating property of the matrix material, but it is difficult to obtain a coarse mesh with a woven fabric without preventing the stitches.

A unidirectional prepreg in which a large number of fibers are aligned in parallel is excellent as a reinforcing material that takes advantage of the original reinforcing performance of high-strength and high-modulus fibers, but the adhesive strength between the fibers is low and tearing occurs. Since it is easy to handle, not only must it be handled carefully, but it must be stored at a relatively low temperature, and even if it has a shelf life of usually less than 6 months even at 15 ° C or less, there is a problem in management at the storage and distribution stage.

Japanese Utility Model Publication No. 56-1747 discloses a sheet in which high modulus filaments such as carbon fibers are arranged in parallel contact as warp yarns, and a single component hydrophobic thermal fusion bonding fiber is placed in a direction perpendicular to the sheet to fuse the sheets. Although the laminated filament sheet for laminated composite material is described, the filaments of the warp are arranged without any gap so as to be in contact with each other, and the impregnability of the matrix resin is poor. Further, the hydrophobic heat-adhesive fiber used for the weft of this technique has a low strength of 3 to 4 g / d level and is melted, and this sheet has extremely low strength in the transverse direction.

Japanese Patent Publication No. 1-39044 discloses that
A non-woven base fabric in which a multifilament having high strength and high elastic modulus is used as a warp, a solution or dispersion of an adhesive or a thermosetting adhesive is applied to a weft, and the intersection point with the warp is bonded with the adhesive is described. There is. In the present invention, the adhesive or its altered material is fixed to equipment such as a roller used for the adhesion treatment, and what is fixedly retained in the equipment is sometimes adhered to the base cloth side to deteriorate the quality of the base cloth. To prevent this, it is necessary to stop the operation and remove the adhered substances. Further, since curing or curing of the adhesive solution or dispersion is required for drying and / or heat curing, it is necessary to allow the adhesive solution or dispersion to stay at a high temperature for a long time.

In Japanese Patent Laid-Open No. 63-66362, a fusion yarn is wound around both warp yarns and weft yarns of a multifilament untwisted or sweet twisted yarn and heat-bonded to each other so that the intersections of the warp yarns and the weft yarns are fused. Although the non-woven base fabric adhered via the multi-filament is described, not only the number of steps for winding the fusion yarn around the multi-filament is increased, but also the multi-filament is fused to secure the adhesiveness and stability of the intersection point of the warp and the weft. 20 yarns
Although it is necessary to wind it uniformly at a winding number of 0 to 800 turns / m, a high level of technology is required to carry out operationally. In addition, the affinity between the fusible yarn and the matrix is not perfect, and the reinforcing effect is likely to decrease due to insufficient adhesive strength.

[0008]

As described above, the non-woven base fabric obtained by the conventional technique has major problems in terms of performance such as resin impregnation property and strength, and in that it requires a production speed and complicated steps. is doing. Further, in the conventional technique, PVA fiber having excellent adhesiveness is used because it has high strength, high elastic modulus, high weather resistance, high alkali resistance, excellent cost performance, and good affinity with the matrix. No non-woven base fabric of PVA-based fibers produced by the excellent no-binder type thermal bonding method of US Pat. In view of the conventional technique, an object of the present invention is to use a PVA-based fiber to bond the intersections of the warp yarns and the weft yarns, which are aligned with each other, by a thermocompression bonding method to obtain a non-woven base fabric excellent in strength and handleability. To provide.

[0009]

[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, the present invention provides a non-woven base fabric in which a plurality of yarns are stacked so that the faces of the yarns arranged in one direction in a plane cross each other and the intersections of the yarns are bonded to each other. At least 10% by weight of the fibers to be melted have a melting point of 220 ° C or higher.
The melting point or fusion temperature is 2 with VA polymer as the sea component.
A non-woven base fabric comprising a PVA-based sea-island fiber having a strength of 7 g / dr or more and having a polymer of less than 10 ° C. as an island component, and the intersections of which are bonded by thermocompression bonding.

The non-woven base fabric of the present invention is a non-woven base fabric in which a plurality of yarns are superposed so that the surfaces of the yarns arranged in one direction in a plane cross each other. The surface in which the threads are arranged in a plane parallel to the length direction (the warp direction) (the warp arrangement surface) and the surface in which the threads are arranged in the width direction (the weft direction) of the non-woven fabric (the weft arrangement surface) are Overlaid. As for the order of overlapping, the structure in which the warp array surface is overlapped on one side or both sides of the weft array surface and the structure in which the weft array surface is overlapped on both sides of the warp array surface are easy to manufacture. In terms of Of course, the warp yarn arrangement surface and the weft yarn arrangement surface do not have to be orthogonal to each other, and may be superposed in the bias direction.

In the non-woven base fabric of the present invention, the weft yarn and the warp yarn are simply superposed, and the strength possessed by the fiber can be sufficiently exhibited. When the shape is maintained by repeating the above-mentioned reversal, the fibers are largely bent up and down, so that the original strength of the warp or the weft cannot be exhibited, which is inconvenient. Further, in the composite molding material, it is preferable that the reinforcing base cloth penetrates through the reinforcing base cloth so that the matrix material is present so that the anchoring effect is increased in order to reinforce the matrix material. However, when the eyes become rough, the tissue becomes unstable and causes the blurring, which is inconvenient because the treatment for preventing the blurring is required. In the present invention, there is no particular limitation on how to arrange the warp arranging surface and the weft arranging surface, but it is preferable that the warp arranging is arranged in two steps above and below the weft, and the upper and lower sides are alternately overlapped with each other. If it is not enough to bond only the intersections of the warp and the wefts, the warp arrangements should be aligned above and below the weft, and the warp should be adhered not only at the intersections of the warp and the weft but also on the entire surface of the warp. It may be a more preferable embodiment because the fabric structure becomes stable.

In the non-woven base fabric of the present invention, the sea component is made of a PVA polymer having a melting point of 220 ° C. or higher, the island component is made of a polymer having a melting point or a fusion temperature of less than 210 ° C., and a strength of 7 g / dr or more. The thermocompression-bondable PVA sea-island fiber is at least 10% of the warp and / or the weft.
Is the point to contain. The thermocompression-bonding PVA-based fiber used in the present invention is a multi-component fiber having a sea-island structure, and a PVA-based polymer having a melting point of 220 ° C. or higher is a sea component. The PVA-based polymer of the present invention has high strength fibers as compared with other general-purpose fiber-forming polymers as described above, and further has excellent adhesiveness to cement, plastics, rubber, paper, etc. Used for. The melting point of the PVA polymer of the sea component that is the matrix is 22.
If the temperature is lower than 0 ° C, the heat resistance and water resistance of the fiber of the present invention are insufficient, and a fiber that can be practically used cannot be obtained. Also, high strength fibers cannot be obtained. It is more preferable that the melting point of the sea component PVA-based polymer is 225 ° C. or higher. There is no particular upper limit to the melting point of the sea component polymer, but the melting point is 2
PVA-based polymers having a temperature of 60 ° C. or higher are not common.

Specific examples of the sea component PVA-based polymer include a polymerization degree of 500 to 24,000 and a saponification degree of 95 to 1.
Highly saponified PVA of 00 mol%. In terms of water resistance and thermocompression bonding, the degree of polymerization is 1500 to 4000, and the degree of saponification is 9
It is more preferably 8 to 100 mol%, and even more preferably 99.5 to 100 mol%. 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 modifying unit is less than 1 mol%, preferably 0.5 mol% or less. 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 PVA-based polymer having a high degree of saponification as a continuous phase, it is possible to obtain a performance close to that of a single fiber having a high melting point, and by using a high melting point polymer as the outermost layer of the fiber, it becomes It is possible to prevent wearing.

As the island component of the sea-island fiber of the present invention, a polymer having a melting point or a fusion temperature of less than 210 ° C. is used. Melting point 210
If the temperature is higher than 0 ° C, the thermocompression bonding temperature becomes too high and the orientation and crystallinity of the PVA-based polymer of the sea component are easily destroyed during thermocompression bonding, which is not preferable. Even if the amorphous polymer has no 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 minimum temperature at which the chips fuse together is melted. An amorphous polymer having a fusion temperature of less than 210 ° C. can be effectively used as the island component polymer of the present invention. The island component polymer preferably has a melting point or a fusion temperature (hereinafter, this temperature is also included in the term "melting point") of 200 ° C. or lower, and more preferably 190 ° C. or lower. Furthermore, it is preferable that the difference in melting point between the sea component and the island component is 15 ° C. or more because the fiber dimensional change during thermocompression bonding becomes small. The difference in melting point is more preferably 30 ° C. or higher, and further preferably 50 ° C. or higher. A polymer having a melting point of less than 210 ° C. has low orientation and low crystallinity, and thus is disadvantageous when it is used in a sea component that is a fiber matrix because it has low strength and low heat resistance. Further, when the low melting point polymer is present on the outermost surface of the fiber, it is likely to be hard-bonded in the fiber manufacturing process, and from this point as well, it is necessary that the low melting point polymer is an island component.

Specific examples of the polymer having a melting point of less than 210 ° C. in the present invention include ethylene / vinyl alcohol copolymer (molar composition ratio = 50/50 to 20/80) and ethylene / vinyl acetate copolymer (molar composition ratio = 92 / 8-20 / 8
0), PVA having a saponification degree of 50 to 88 mol%, and P modified by 2 to 10 mol% with a monomer having an ionic group.
VA, polyvinyl butyral, polyvinyl formal,
Examples thereof include PVA modified with a vinyl ester of a fatty acid having 3 to 20 carbon atoms, a modified acrylic resin, a hydrocarbon elastomer such as polyisoprene, and a polyurethane elastomer. Above all, in terms of heat adhesion, performance reproduction (stability), and cost, ethylene / vinyl alcohol copolymer (molar composition ratio = 50/50 to 20/8), ethylene / vinyl acetate copolymer (molar composition ratio = 92). / 8 to 20/8
The PVA-based polymer of 0) is a thermocompression-bondable PV used in the present invention.
It is useful as an island component of A-based fibers. There is no particular limitation on the degree of polymerization of the island component polymer, but it is important that the island component does not contribute to the fiber strength but to the adhesiveness. ~ 1000 is preferred.

The blending ratio of the sea component / island component of the thermocompression-bonding PVA-based sea-island fiber used in the present invention is 98/2 to 5 by weight.
The range is 5/45. If the content of the high melting point PVA polymer of the sea component is less than 55%, high strength fibers cannot be obtained. In addition, the high melting point PVA-based polymer is less than 55%,
When the content of the low melting point polymer is more than 45%, the low melting point polymer tends to become a sea component, which is not preferable from the viewpoint of hardening. On the other hand, if the content of the low melting point polymer is less than 2%, the thermocompression bonding performance that can withstand practical use cannot be obtained. Due to the balance between strength and thermocompression bonding, the sea / island blend ratio is 95/5 to 60
/ 40 is more preferable, and 92/8 to 70/30 is further preferable.

In the thermocompression-bonding PVA-based fiber used in the present invention, the low melting point polymer of the island component is not preferably present in the outermost layer of the fiber, but is preferably present near the outermost layer. The minimum thickness of the sea component near the outermost layer (the closest distance to the fiber outermost surface of the low melting point polymer of the island component) is
It is important for the high melting point PVA-based polymer of the outermost layer to be broken during thermocompression bonding, and the low melting point water resistant polymer of the island component to be extruded onto the surface to obtain an adhesive force. It is preferable that at least a part of the island component is present within 0.01 to 2 μm from the outermost surface layer. The island component may be uniformly distributed in the fiber cross-sectional direction, but it is more preferable to distribute the island component more concentratedly on the surface side. Further, the island component may be continuous in the fiber axis direction,
It is not always necessary to be continuous, but rather spherical shape, intermittent rod shape or rugby ball shape may be preferable in order to reduce dimensional change during thermocompression bonding.

The thermocompression bonding PVA fiber used in the present invention is 7
It has a strength of g / dr or more. If the strength is less than 7 g / dr, only a low-strength non-woven base fabric can be obtained, and a sufficient reinforcing effect cannot be obtained. The thermocompression-bonding PVA fiber used in the present invention exerts its function by thermocompression bonding. It is important to have sufficient strength even if the strength is slightly lowered by thermocompression bonding, and for this purpose, the strength before thermocompression bonding is required to be high. The strength is more preferably 8 g / dr or more, further preferably 10 g / dr or more.

The number of islands in each fiber cross section of the sea-island fiber used in the present invention is 1 or more. When the number of islands is 4 or less, it has a drawback that it is difficult to allow the low-melting point polymer phase to exist near the fiber surface layer, but use of a composite spinneret that allows the island component to exist near the fiber surface layer Can be obtained by For example, when the number of islands is one, there are many eccentric core-sheath composite fibers in which the island component is present near the fiber surface layer, and when there are four islands and at least one of them is near the fiber surface layer. The core-sheath composite fiber can be preferably used in the present invention. However, a mixed spun fiber obtained by simply blending the island component polymer liquid in the sea component polymer liquid without using a special composite spinning device is preferable.
The number of islands is preferably 50 or more, more preferably 100 or more from the viewpoint of ease of extruding the island component during thermocompression bonding. By controlling the phase separation state of the sea component polymer and the island component polymer in the undiluted solution, The number of islands can easily be 100 or more.

Next, a method for producing fibers used in the non-woven base fabric of the present invention will be described. The above-mentioned high melting point PVA-based polymer and low melting point polymer are dissolved in a solvent at a ratio of 98/2 to 55/45 to obtain a spinning dope. The solvent mentioned here must be a solvent that dissolves at least the high melting point PVA polymer. More preferably, it is a common solvent that also dissolves the low melting point polymer, but it does not always dissolve,
It can be used if it can be pulverized and dispersed so as to be dispersed in a high melting point PVA polymer solution to 10 μm or less. The dispersed particle size is preferably 5 μm or less, more preferably 1 μm or less. Even if dissolved in a common solvent for both polymers, a homogeneous transparent solution cannot be obtained depending on the compatibility of both polymers.
Rather, in the spinning stock solution, the high melting point PVA-based polymer becomes a matrix (sea) phase, and the low melting point polymer droplets become a finely dispersed polymer blend solution in an island phase, resulting in a turbid homogeneous finely dispersed phase separation liquid. Is preferred. As a matter of course, when both polymers have good compatibility, a homogeneous transparent solution can be obtained, and it can be produced by preparing the undiluted solution and the spinning conditions so that the high melting point polymer becomes the sea component during fiber formation.

Specific examples of the solvent used in the method for producing the fiber used for producing the nonwoven base fabric of the present invention include dimethyl sulfoxide (hereinafter abbreviated as DMSO), dimethylacetamide, N-
Examples include polar solvents such as methylpyrrolidone and dimethylimidazolidinone; polyhydric alcohols such as glycerin and ethylene glycol; strong acids such as nitric acid and sulfuric acid; concentrated aqueous solutions such as rhodanate and zinc chloride; and mixtures of these solvents. To be DMSO is especially low temperature solubility, low toxicity,
It is preferable in terms of low corrosion. Add both polymers to the solvent and stir to dissolve, or strongly stir to finely disperse when dissolving, especially when it becomes a phase-separated liquid, and also perform low-speed stirring to the extent that bubbles do not bite so as not to coagulate and settle while leaving degassing. Consideration such as continuing is preferable.

Next, the viscosity of the spinning dope varies depending on the spinning method, but is 5 to 500 at the temperature near the nozzle during spinning.
0 poise is preferred. For example, in dry spinning, 500 to 50
The poise concentration and the undiluted solution temperature are adjusted so as to be 00 poise, 80-800 poise for dry-wet spinning, and 5-200 poise for wet spinning. In addition to both polymers, a compatibilizer, a phase separation accelerator, etc. may be appropriately added for controlling the sea-island structure of both polymers in the spinning stock solution state and the fiber state. Various additives may be added to the stock solution for other specific purposes. For example, an antioxidant for preventing deterioration of the polymer,
Examples thereof include light stabilizers, ultraviolet absorbers, pigments and dyes for coloring fibers, surfactants for controlling interfacial tension, acids for adjusting pH and alkaline.

Next, the obtained stock solution is subjected to dry spinning, dry wet spinning or wet spinning. In dry spinning, the high melting point polymer is a matrix (sea component) while the solvent evaporates.
Select the spinning and drawing conditions so that the low melting point polymer becomes islands,
The obtained fiber is wound up. In dry-wet spinning, the stock solution is once discharged from a nozzle into an inert gas layer (for example, an air layer), then passed through a solidification solution, solidification and extraction of the stock solution solvent are performed, wet drawing and dry heat drawing are performed, and the film is wound up. . Or in wet spinning, the stock solution is directly discharged from the nozzle to the solidifying solution,
After solidification and extraction, wet stretching and dry heat stretching are applied and wound up. In either spinning method, it is necessary to consider the stock solution and spinning conditions so that the high melting point polymer becomes the sea component and the low melting point polymer becomes the island component. Specifically, it is effective to increase the blending ratio of the high melting point polymer to be the sea component. In addition, it is effective to set the stock solution and the spinning conditions so as to facilitate phase separation.

Further, in the method for producing the fiber used in the present invention, since the strength is set to 7 g / dr or more, a uniform solidified yarn is obtained in the solidifying process. To confirm that uniform solidification was performed, the cross section of the fiber after stretching was observed with an optical microscope, and when a fiber having a substantially circular cross section was obtained, it can be determined that uniform solidification was performed. Conventionally, when a concentrated Glauber's salt aqueous solution generally used for spinning PVA is used in the solidifying bath, it becomes nonuniformly solidified, so that the cross section becomes an eyebrow type and the stretch orientation cannot be sufficiently performed, and a strength of 7 g / dr or more is obtained. I can't. In addition, when boric acid is added to the stock solution and solidified in an alkaline dehydration salt bath, compared to the case where a concentrated aqueous solution of Glauber's salt is used in the solidification bath, the solidification approaches uniform solidification, resulting in a flat cross section, but not a circular shape. Is insufficient. 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 are sea 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, the solidification is uniform, so that the cross section becomes substantially circular and sufficient oriented crystallization can be performed by the subsequent wet drawing and dry heat drawing. It is possible to achieve 7 g / dr or more. 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. It should be noted that these solidifying baths do not necessarily have to have solidifying ability with respect to the low melting point polymer which becomes the island component. Extremely low-melting polymers can be spun even if they are soluble in the solidifying bath. In this case, however, if the blending ratio of the high melting point polymer / low melting point polymer is more than 6/4, the amount of the low melting point polymer is too large, it will be eluted in the solidifying bath and the fibers will be hardened, which is not preferable.
It is more preferable that the low melting point polymer is less than 7/3. When the low-melting point polymer is soluble in the solidifying bath, the low-melting point polymer tends to move in the surface direction of the solidified thread with the stock solution solvent during solidification, and tends to be distributed more in the surface layer than in the central part of the fiber. It has been found that an unexpected preferable tendency is that the decrease in the thermocompression bonding property, which is the object of the present invention, is small even if the blending amount of the melting point polymer is small. If the blending amount of the low melting point polymer is small, there is also an advantage that high strength fibers can be obtained.

As described above, the thermocompression bonding property P used in the present invention.
In contrast to the core-sheath composite heat-adhesive fiber in the conventional hydrophobic polymer in which the core is a high melting point polymer and the sheath is a low melting point polymer, the VA fiber has a sea component as a high melting point polymer and an island component as a high melting point polymer. As a low-melting point polymer, it usually exhibits excellent fiber performance with a high-orientation, highly crystalline high-melting point PVA-based polymer, and the high-melting point PVA-based polymer phase of the fiber outermost layer is broken during thermocompression bonding (high temperature and high pressure application), The heat-adhesive low-melting point polymer that forms islands near the surface layer is extruded on the fiber surface and adheres to the island component polymer of another fiber, or by adhering to the high component polymer of the sea component, It ensures thermocompression bonding. Highly oriented and highly crystallized high melting point PVA-based polymer forms a matrix phase, so even if the island component is low oriented and low crystalline low melting point polymer, it has excellent strength and dimensional stability. Also, since the matrix phase is not greatly affected by this, the dimensional change during thermocompression bonding is small and high strength can be obtained even after thermocompression bonding.

In the non-woven base fabric of the present invention, the warp yarn and / or the weft yarn is not particularly limited whether it is a filament (multi or mono) or a spun yarn, but at least 1
0% must contain the thermocompression-bondable PVA-based fiber. If the content of both warp and weft is less than 10%, the adhesive strength after thermocompression bonding at the intersection of the warp and the weft is insufficient, the texture of the nonwoven base fabric becomes unstable, and the handleability becomes poor. . Thermocompression bonding PVA of warp and / or weft
It is more preferable that the content of the system fibers is 20% or more,
It is more preferably 40% or more. When the adhesive strength at the intersection is particularly required, it is more preferable to use the thermocompression-bonding PVA-based fiber alone. The thermocompression-bondable PVA-based fiber has a high strength of 7 g / dr or more, and is characterized in that it can be used alone in the warp and / or the weft. On the other hand, when a high-strength filament alone, a multifilament twisted with the thermocompression-bonding PVA-based filament, a spun yarn consisting of only high-strength staple, or a spun yarn obtained by mixing the thermocompression-bonding PVA-based staple is used as a warp, for example. A non-woven base fabric having a higher strength in the warp direction can be obtained. Further, a spun yarn composed of the thermocompression bonding PVA-based fiber is intertwisted with a high-strength filament, or a cord in which a filament composed of the thermocompression-bondable PVA fiber is interlaced with a high-strength spun yarn is used as a warp and / or a weft. You can also

Examples of fibers that can be used in the present invention other than thermocompression-bonding PVA-based fibers include ordinary type or high-strength type vinylon, cellulosic fibers, aramid fibers, carbon fibers, glass fibers and the like. When a multifilament is used for the warp and / or the weft, the twist number is preferably 0 to 20 t / m. further,
Non-twisting is preferable because it increases the adhesion area at the intersection and facilitates impregnation with the matrix resin. The thickness of the warp and weft is 50 to 20
00 dr is preferable, and 150 to 1500 dr is more preferable. The warp yarn array density is 0.3 to 30 yarns /
cm is preferable, 0.5 to 15 lines / cm is more preferable, and 1 to 10 lines / cm is further preferable.
The arrangement density of the wefts is preferably 0.3 to 20 yarns / cm,
It is more preferably 0.5 to 10 fibers / cm, and 1 to 5
It is more preferable that the number is books / cm.

Another point of the present invention is that the non-woven base fabric of the present invention is formed by adhering the intersections of the warp and the weft made of the above fibers by a thermocompression bonding method. In the present invention, thermocompression bonding means that the base cloth is adhered by applying a linear pressure of 1 kg / cm or more or a surface pressure of ² kg / cm ² or more at a temperature of 80 ° C. or more. Temperature is less than 80 ℃,
When the linear pressure is less than 1 kg / cm or the surface pressure is less than 2 kg / cm ² , the high-melting point PVA-based polymer phase in the outermost layer of the thermocompression-bonding PVA-based fiber is not broken and the low-melting point polymer of the island component is not extruded on the fiber surface. Therefore, the adhesive strength is low. By heating the high melting point polymer of the outermost layer and applying pressure in a softened state, the polymer phase of the outermost layer is broken, and the low melting point polymer of the adhesive component near the surface layer can be extruded and adhered. If the thermocompression bonding temperature is too high, the molecular orientation of the sea component and the crystals may be broken, so the temperature should not be higher than 230 ° C. The appropriate pressure bonding temperature changes depending on the sea / island polymer specifications, distribution state and applied pressure, etc.
The temperature is preferably from 00 to 210 ° C, more preferably from 120 to 200 ° C, even more preferably from 130 to 190 ° C.

If the applied pressure is too high, the fiber structure of the sea component and the structure of fibers other than the thermocompression-bonding PVA-based fibers that are mixed will be broken, and the fiber strength after thermocompression bonding will decrease, which is not preferable. The linear pressure applied by a thermal calendar roller or the like is preferably 500 kg / cm or less. Linear pressure is 200k
More preferably g / cm or less, 100 kg / c
It is more preferable that the thickness is m or less, and the surface pressure by hot pressing or the like is preferably 1000 kg / cm ² or less. Surface pressure is 40
More preferably 0 kg / cm ² or less, 200 k
It is more preferably g / cm ² or less. Usually 5-5
Linear pressure of 0 kg / cm or 10 to 100 kg / cm ²
Surface pressure is used. Thermocompression bonding can be performed in a short time of about 0.01 to 10 seconds. The ability to bond in a short time is a very important property of the thermocompression bonding method. In the case of the base fabric of the present invention, if the thermocompression bonding time is set to 10 minutes or longer, the adhesive force tends to decrease. The cause of this is unknown, but it is presumed to be related to crystallization of the polymer. Therefore, the hot pressing method of the surface pressure application type having a long processing time and the thermal calender roll method of the linear pressure application type having a short processing time can be more preferably used for thermocompression bonding.

The conventional production of a non-woven base fabric requires a step of applying an adhesive and a drying and curing step for expressing the adhesive force during the production step, and more than 1 minute is required for the drying and curing. Therefore, a large amount of capital investment is required and high-speed production is difficult. In addition, the adhesive and its degenerated substances stick to the equipment such as rollers in the manufacturing process, which causes defects in the non-woven fabric, and it is necessary to stop the equipment and remove the adhered substances. is there. Further, the melting point fiber used in the conventional non-woven base fabric is a heat-adhesive polymer alone, or a sheath is a core-sheath composite fiber of a heat-adhesive polymer, and the heat-fusion polymer is exposed on the fiber surface. There are many types,
Although less prominent than the adhesives described above, there is sticking of the fused fibers to rollers such as hot rollers during the manufacturing process. On the other hand, thermocompression bonding PVA used in the present invention
In the case of system fibers, the fiber surface is coated with a high melting point PVA polymer, and the fusion component near the fiber surface oozes out and adheres to the fiber surface only when thermocompression bonding is applied. It can be further reduced as compared with the heat-adhesive fiber.

The definition of parameters and the measuring method thereof in the present invention are as follows. 1. Melting point In the case of a crystalline polymer, a differential scanning calorimeter (DSC-20) manufactured by METTLER CORPORATION was used, and the sample polymer was placed under nitrogen at 20
When the temperature is raised at a rate of ° C / min, the temperature showing an endothermic peak is measured.

2. Fusing temperature In the case of an amorphous polymer, when the polymer chips are placed in a hot air dryer at a specified temperature and a pressure of 0.1 kg / cm ² is applied for 10 minutes, the chips melt to the extent that the boundaries between the chips cannot be determined. Measure the lowest temperature to wear.

3. Fiber strength In accordance with JIS-1015, the single fiber strength is a test length of 20 mm,
A tensile test is performed at a tensile rate of 50% / min.

[0035]

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, blend ratios and% are values based on weight unless otherwise specified. Example 1 Polymerization degree 3800, saponification degree 99.9 mol%, melting point 23
PVA of 6 ° C., ethylene / vinyl alcohol copolymer = 47 to 53 (molar ratio), polymerization degree of 750 and melting point of 16
The polymers at 2 ° C. were dissolved in 90 ° C. DMSO by mixing and stirring under nitrogen. The high melting point PVA polymer / low melting point blend ratio was 90/10. The spinning solution was passed through a nozzle having a hole diameter of 0.06 mm and a number of holes of 200, and wet-spun in a solidified solution of 70% methanol and 30% DMSO at 3 ° C. The obtained solidified Itoshino was cloudy, and it was presumed that both polymers were phase-separated. At this time, no special turbidity was generated in the solidified liquid. The solidified yarn is subjected to a 5.0-fold wet drawing, immersed in a methanol solution to extract and wash DMSO in the solidified yarn, add a mineral oil-based oil agent, dry at 100 ° C., and then at 225 ° C. Dry heat stretched to a total draw ratio of 15 times, 500 dr / 200f
A multifilament of Single yarn strength is 15g / dr
there were. Further, from the cross-sectional observation, it is a circular cross-section, the high melting point PVA is the sea component, the low melting point polymer is the island component, there are at least 100 islands,
It was found that many island components were present within 1 μ of the outermost surface.

The multifilaments were arranged as warps at an interval of 1 / cm without twisting. On this warp arranging surface, the same multifilaments as the warp were arranged as wefts at an interval of 2 / cm. Further, the same warp as that described above was arranged at an interval of 1 thread / cm, and was superposed on the weft arrangement surface. At this time, they were arranged with a 0.5 cm offset from the lower warp arrangement surface. The obtained warp and weft arranged in a lattice at intervals of 0.5 cm at a temperature of 210 ° C and a linear pressure of 60 kg.
Thermal calendering was performed under the condition of / cm and thermocompression bonding was performed. The resulting non-woven base fabric has an adhesive strength at the intersection of the warp and the weft of 8
It was 0 g, and the intersection did not come off during handling by hand. Further, the multifilament constituting the base cloth after thermocompression bonding had a strength of 13 g / dr, and had sufficient performance as a reinforcing non-woven base cloth.

Comparative Example 1 A multi-filament of 500d / 200f having a degree of polymerization of 1750, a degree of saponification of 99.9 mol% and a melting point of 233 ° C. and made of only PVA and made of PVA only and having a strength of 14 g / dr was used. Similar to Example 1, a warp and a weft arranged in a lattice were thermocompression bonded in the same manner as in Example 1. The obtained non-woven base fabric has an adhesive force of 10 g or less, and the single yarn is separated,
It could not be handled as a base cloth.

Example 2 In the same manner as in Example 1, the sea component was PVA having a polymerization degree of 1750, a saponification degree of 99.9 mol% and a melting point of 233 ° C., and the island component was a polymerization degree of 1100 and a copolymerization. Molar ratio 32 /
It is an ethylene / vinyl acetate copolymer with a fusion temperature of 68 or less at 50 ° C., a sea / island blend ratio of 80/20, a strength of 11 g / dr, a circular cross section, and 100 islands. As described above, a multifilament of 1000d / 400f PVA-based sea-island fiber having a large number of island components within 0.5 μm from the outermost surface was obtained. This multifilament was twisted 1/1 with a 100d / 500f vinylon filament having a strength of 17g / dr. As warp, vinylon filaments having a strength of 14 g / dr and 1000 d / 500 f were arranged without twisting at an interval of 1 filament / cm, and the content of the PVA-based sea-island fiber was 50 on the warp arrangement surface.
% 1/1 twisted filament as weft yarn 2 / c
Arrayed at m intervals. On top of that, add the same warp 1
They were arranged at an interval of books / cm and were stacked on the weft arrangement surface. At this time, they were arranged with a 0.5 cm offset from the lower warp arrangement surface.
The obtained warp yarns and weft yarns arranged in a lattice at intervals of 0.5 cm were subjected to thermal calendaring under the conditions of a temperature of 200 ° C., a linear pressure of 40 kg / cm and a treatment time of 1 second or less, and thermocompression bonding was performed. The resulting non-woven base fabric had a maximum adhesive force of 60 g at the intersection of the warp and the weft.

At the intersection of the warp and the weft in the non-woven fabric, there was no adhesive force at the intersection where the PVA-based sea-island fiber contained in the weft did not come into contact with the warp at all, but during handling by hand, the warp or the weft was There was no continuous disengagement and there was no problem in handling. The warp yarn and the weft yarn constituting the base fabric after thermocompression bonding had a strength of 11 g / dr or more, which was high strength. Further, the shrinkage factor when this base fabric was freely shrunk at 180 ° C. for 15 minutes was 3% or less, and the dimensional stability at high temperature was excellent.

Example 3 A sea-island fiber of the same polymer as in Example 2, prepared using a method similar to that of Example 1, with a sea / island blend ratio of 90.
/ 10, circular cross section, 100 or more islands, a distance of 0.5 μ or less from the outermost surface of the island component, and a strength of 12 g / d. This staple is used as a 20th spun yarn and as a warp. The yarns were arranged at an interval of 5 yarns / cm, and 10-spun spun yarns having the same polymer composition as the warp yarns were arranged at an interval of 5 yarns / cm as weft yarns and were superposed on the warp yarn arranging surface of the 20th yarn spun yarns. Further, the same 20th spun yarn was arranged as a warp at an interval of 5 threads / cm, and was superposed on the weft arrangement surface. At this time, the upper and lower warp yarns were superposed so as to sandwich the weft yarn. In this way, the warp yarns and the weft yarns are arranged in a lattice pattern at an interval of 5 threads / cm, and the temperature is 190 ° C.
Thermal calendering was performed under the conditions of 0 kg / cm and a treatment time of 1 second or less, and thermocompression bonding was performed. The adhesive strength of the obtained non-woven base fabric was 10 g, and the warp or weft did not come off during the handling of this non-woven base fabric. The strength (single fiber strength) of the spun yarn constituting the non-woven base fabric was 10 g / dr.

COMPARATIVE EXAMPLE 2 The commercially available vinylon staple was mixed with 5% of the sea-island fiber staple used in Example 3 and spun yarns of No. 20 and No. 10 yarns were piled with warp and weft in the same manner as in Example 3. The obtained array of grids was thermocompression bonded in the same manner as in Example 3. The resulting non-woven base fabric had a small adhesive force between the warp and the weft, and could not be handled as a base fabric because it was loose.

[0042]

EFFECTS OF THE INVENTION According to the present invention, at least 10% of high-strength, thermocompression-bonding PVA-based sea-island fiber is contained in the warp and / or the weft, and the intersections of the warp yarns are laminated by the thermocompression bonding method. It is a non-woven base cloth. By using the high-strength thermocompression-bonding PVA-based sea-island fiber, which has not been obtained in the past, in a non-woven base fabric, the high strength, high elastic modulus, which is a characteristic of PVA-based fibers,
A non-woven base fabric that takes advantage of alkali resistance, heat resistance, and weather resistance.
The present invention enables continuous production by a heat-bonding method without an adhesive, which is a more efficient and rationalized process than an adhesive method using an adhesive, which has been problematic in the past.

The conventional heat-sealing fiber is a core-sheath composite fiber having a single heat-sealing component or having a heat-sealing component on the fiber surface. Alternatively, the deteriorated substance adhered to the surface, and continuous operation could not be performed for a long time. In the thermocompression-bonding PVA-based sea-island fiber used in the present invention, the PVA-based polymer on the fiber surface does not fuse at the temperature of the heat roll during thermocompression bonding, and the heat-fusion component oozes out on the surface only when temperature and pressure are applied simultaneously. Therefore, the sticking to the surface of the hot roll can be extremely reduced. The thermocompression bonding PVA used in the present invention
Since the sea-based fiber is a PVA-based polymer having a high melting point and high crystallinity in the sea component that is the matrix phase, it has higher dimensional stability than the conventional heat-fusible fiber, and therefore the dimensional change during thermocompression bonding is small, and The obtained nonwoven base fabric has good dimensional stability at high temperatures. Further, since the thermocompression-bonding PVA-based fiber has higher strength than the conventional heat-fusible fiber, the obtained non-woven base fabric has high tenacity not only in the warp direction but also in the weft direction, and is used for cement, asphalt, paper and plastic. It is possible to reduce the basis weight as a reinforcing base fabric. Especially when used as a cement reinforcement material as a non-woven base fabric that has both high strength and alkali resistance,
Since the obtained composite molded article has high strength, it can be reduced in weight and is useful as a building material.

 ─────────────────────────────────────────────────── ─── Continued Front Page (72) Inventor Shunpei Naramura, 1621 Sakazu, Kurashiki, Okayama Prefecture, Kuraray Co., Ltd. (72) Inventor, Satoru Kobayashi, 1621, Satsuki, Kurashiki, Okayama, Kuraray Co., Ltd.

Claims (1)

[Claims] 1. A non-woven fabric in which a plurality of yarns are superposed so that the faces of the yarns arranged in one direction in a plane intersect and the intersections of the yarns are adhered to each other. 7% strength by weight of polyvinyl alcohol polymer having a melting point of 220 ° C. or higher as a sea component and a polymer having a melting point or a fusion temperature of less than 210 ° C. as an island component
A non-woven fabric, which is a polyvinyl alcohol-based sea-island fiber of dr or more, and the intersections are bonded by thermocompression bonding.