JP3197928B2 - Method for producing polyvinyl alcohol-based long-fiber nonwoven fabric - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a nonwoven fabric in which polyvinyl alcohol continuous filament fibers are spread to a monofilament level and deposited in a non-oriented state.

[0002]

2. Description of the Related Art Polyvinyl alcohol fibers are processed into woven or knitted fabrics or nonwoven fabrics because of their excellent weather resistance and strength, and are used for various purposes mainly in the field of industrial materials. At present, long-fiber nonwoven fabrics are used in various applications because they have many characteristics such as a very large number of nonwoven fabrics having high strength and no loss of fibers. Further, the types of fiber materials constituting the nonwoven fabric are also made of various resins. Conventionally, as a fiber material constituting a long-fiber nonwoven fabric, a fiber obtained by a so-called melt spinning method, which is spun from a hot-melt (thermoplastic) resin and stretched, for example, polyester, polypropylene, nylon, or the like is used. Have been. These are mainly made into a long-fiber nonwoven fabric by a very long manufacturing method called a spun bond method, in which a process of spinning → drawing → opening → collection → adhesion is continuously performed. Various methods have been proposed for the fiber-spreading step in this method. For example, an electrostatic fiber-spreading method as disclosed in Japanese Patent Publication No. 37-4993, that is, repulsion thereof by imparting static electricity to a multi-fiber bundle. A means for uniformly opening the fibers by force is mainly used. The method of imparting static electricity to the multi-fiber bundle is roughly classified into a friction charging method with a fixed friction element and a forced charging method in which a high voltage is externally applied. In order to charge the fiber bundle so that it can be effectively opened only by friction with the fixed friction element, an excessive tension must be applied to the fiber bundle. As a result, the fiber bundle is liable to be fluffed, and abrasion of the friction element is also a serious problem. Among the forced charging methods, a direct current high voltage application method by corona discharge is mainly used. These electrostatic fiber-spreading methods are applied only to hydrophobic fibers obtained by melt spinning, and are not applied to hydrophilic fibers that are hardly charged, such as polyvinyl alcohol fibers. Also,
Such hydrophilic fibers are often spun by wet spinning or the like.

[0003] Since highly hydrophilic fibers such as polyvinyl alcohol fibers and rayon are difficult to spread and form into webs by charging, the tow is mechanically moved in the width direction as proposed in JP-A-2-191760. It is made into a web by spreading it, or made into a web by a wet method to obtain a long-fiber nonwoven fabric. With such a method, the fiber bundle cannot be opened to a monofilament shape, and the fibers are oriented in the longitudinal direction and have high mechanical anisotropy. For this reason, in the method disclosed in Japanese Patent Application Laid-Open No. 2-191760, reinforcing fibers are integrally bonded in parallel with the width direction at a certain interval to compensate for the strength in the width direction.

[0004] Shape stabilization of nonwoven fabrics is also performed by fiber entanglement such as needle punching or water entanglement. However, long fiber nonwoven fabrics are mostly bonded by bonding, and spunbonded nonwoven fabrics have a high thermal stability. The thermocompression bonding method is mainly used because the fibers are made of a fusible resin. The heat-fused spunbonded nonwoven fabric may be made of a single-component long fiber, or may be mixed with a heat-fusible fiber separately from the main fiber, but these are uniformly mixed into the continuous fiber web. Because it is very difficult, two or more resins with different melting points are supplied to the spinning head and spun from different nozzles and mixed, or spun from the same nozzle to make the constituent fibers themselves with two different melting points. In some cases, the composite fiber is made of the above resin. In addition, in the case of using the spunbond method, in order to take a very long continuous process as described above, the process is performed using a fiber that can be applied to a melt spinning method in which a fiber is obtained by a relatively simple process, and a dry method or ,
Regarding the fiber spun by the wet method or the dry-wet method, there is almost no example in which a long-fiber nonwoven fabric is formed by a spunbond method.

[0005]

The long-fiber nonwoven fabric has many features such as high strength and no loss of fibers.
A long-fiber nonwoven fabric of a polyvinyl alcohol fiber in which fibers are deposited in a substantially non-oriented state has not been known. The non-woven fabric obtained by the method of JP-A-2-191760 is obtained by arranging fibers mechanically widened from a tow state in a direction substantially parallel to the length direction thereof. Very weak if no reinforcing fibers are introduced. In addition, the nonwoven fabric is liable to cause unevenness in thickness, that is, nonuniform weight per unit area in order to mechanically widen the tow, and it is difficult to produce a nonwoven fabric having a low basis weight or a very thick basis weight.

The present invention comprises a polyvinyl alcohol continuous filament fiber, which is uniformly spread to a monofilament level and deposited in a substantially non-oriented state. An object of the present invention is to provide a long-fiber nonwoven fabric having a low modulus, high strength, and low mechanical anisotropy.

[0007]

Means for Solving the Problems The present inventors have made intensive studies to solve this problem, which could not be achieved by the above-mentioned prior art, and as a result, have reached the following invention. It is. That is, the present invention is to open the polyvinyl alcohol-based continuous filament fibers by charging, pass the opened fiber bundle through an air gun, open the fibers in a substantially monofilament shape, deposit them in a non-oriented state, and form them with an adhesive resin. In the method for producing a stabilized long-fiber nonwoven fabric, the moisture content of the filament fibers before the charge-spreading treatment is set at 1.
It is 5% or less, in absolute humidity _{0.010kg-H 2 O / kg-} dry air under the following ambient, the absolute value of the charged voltage of the fiber bundle is 0.5K
V. or more, and the opened fiber bundle is blown into the hood gradually narrowed from the inlet to the outlet provided immediately below the air gun, thereby forming a non-woven cloth. A method for producing a polyvinyl alcohol-based long-fiber nonwoven fabric, wherein the tensile strength ratio in the longitudinal direction / cloth width direction is 0.5 to 1.5, and the present invention relates to a polyvinyl alcohol-based continuous filament fiber. The heat-bonding continuous filament fiber is opened by electrification, and both opened fiber bundles are passed through an air gun to be substantially monofilament-shaped and deposited in a non-oriented state. In the method for producing a long-fiber nonwoven fabric whose form has been stabilized by heat fusion, the moisture content of the filament fibers before the charge opening process is set to 1.5% or less,
Air gun in the absolute humidity _{0.010kg-H 2 O / kg-} dry air under the following ambient, the absolute value of the charged voltage of the fiber bundle is subjected to charging opening process so that the above 0.5 KV, and the dispersed fibers bundle Is blown into a hood that is gradually narrowed from an inlet portion provided to an outlet portion to a outlet portion, so that the tensile strength ratio in the fabric longitudinal direction / cloth width direction of the nonwoven fabric is 0.5 to 1.5.
A method for producing a polyvinyl alcohol-based long-fiber nonwoven fabric.

Hereinafter, the present invention will be described in detail. The fiber used for producing the nonwoven fabric of the present invention is a non-twisted continuous multifilament obtained by spinning and stretching a polyvinyl alcohol-based polymer by a dry, wet, or dry-wet method. Although a nonwoven fabric can be directly connected to the spinning process, the process becomes abnormally long. Therefore, it is practical to use a nonwoven fabric which is once wound around a bobbin or the like so as not to be mixed. In particular, when a fiber bundle obtained by a wet method is used, it is preferable to wash out inorganic salts remaining in the fiber as much as possible. In addition, it is generally desirable not to use an oil agent in order to reduce the chargeability and the dispersion of fibers.

Opening of the fiber bundle is performed by electrostatic opening by charging by friction and contact peeling. Before charging, the chargeability of the fiber, the variation between monofilaments,
That is, in order to improve the separability, the water content is adjusted to a dry state of 1.5 wt% or less, preferably 0.5 wt% or less. Also, friction, atmospheric conditions ambient to make contact peeling electrification efficiently, in particular, the absolute humidity 0.010kg-H ₂ O / kg
-Dry air or less, _{preferably, 0.006kg-H 2 O / kg} -dry a
Friction and contact peeling and electrification are performed in a state adjusted to ir or less. Ambient temperature and humidity conditions, particularly, greatly affect the adsorption moisture on the fiber surface and the maintenance of the charged state.If the moisture content of the fiber is too high, the fiber will not be charged by any method, and if the absolute humidity is too high. Immediately after the friction, even if the charging of the fibers is confirmed, the time during which this state is maintained is extremely short, and the multi-fiber bundle cannot be opened to the monofilament level by the repulsive force due to the charging. Adjusting these conditions is very important for friction and contact peeling / charging of a fiber bundle made of a polyvinyl alcohol-based polymer that is hydrophilic and hard to be charged. Under the conditions adjusted as described above, the sheet is charged and opened by friction and contact peeling by the following method invented by the present inventors to form a sheet.

That is, as shown in FIG. 1, after a fiber bundle (3) is rubbed by a fixed friction element (6), it is driven by a metal roll (7) which is driven to rotate and an elastomer which is rotated by friction with the metal roll. Elastomer roll with coated surface
(8), or by passing through a metal Nelson roll (7, 7a), thereby charging by contact and separation with the elastomer roll and the metal roll. The friction by the fixed friction element is performed to facilitate the main charging performed in the contact peeling step, unlike the conventional method in which charging is performed by friction with only the fixed friction element. That is, the fiber bundle is squeezed and lightly charged by the friction with the fixed friction element, the fiber bundle spreads at the contact portion with the roll, and becomes flatter, the contact area between each filament constituting the fiber bundle and the roll increases, and the fiber bundle The whole is more uniformly charged. Therefore, there is no need to increase the contact pressure with the friction element, and there is no problem such as abrasion of the friction element surface or fluffing of the fiber bundle. Due to such friction and contact peeling, the fiber bundle depends on the yarn denier of the fiber bundle and the number of filaments, but at least the absolute value of the charged voltage is 0.5 K
Charged to V or higher and opened.

As shown in FIGS. 2 and 3, the opened fiber bundle (10) is guided to an air gun (11) for ejecting the opened fiber bundle by the action of compressed air flow, one bundle per gun. The fiber bundle is opened to a monofilament state by passing through an air gun. With this as one unit, a number of air guns are arranged in a line, and side guns (12) for injecting air only are installed on both sides. Immediately below this gun row, the fiber width is blown into a hood (13) surrounded by a flat plate, and the slit width in the direction perpendicular to the gun row is gradually narrowed from the inlet to the outlet, and passed through, It collects continuously on the collection net (15) below the hood. By using such a hood, the spread fiber and compressed air flow from a plurality of air guns blown into the hood, the compressed air flow from the side gun,
By the effect that the food is narrowed toward the tip,
The internal wind speed distribution is made uniform up to the tip. By this action, the fibers blown as a fiber bundle unit by each air gun promotes fiber opening and generate a large swinging effect in the air gun row width direction in the hood, and fiber filaments from adjacent air guns And the sheet basis weight in the sheet width direction is made uniform. The sheet-like web collected at this time may be either a single layer or a layer collected in a multi-layered state. The collection web is very uniform in sheet weight by the action of the fiber bundle being opened and passing through the hood, and each filament which is uniformly opened to the monofilament level,
It is collected in a substantially non-oriented state. After collection,
The web is impregnated in a binder resin, for example, a solution of polyvinyl alcohol, polyvinyl acetate, polyacrylate, or an emulsion, dried after being squeezed, or sprayed with a binder resin liquid, or thermally fused. It is bonded by, for example, uniformly spraying a conductive resin powder to form a long-fiber nonwoven fabric. The amount of the resin to be adhered is preferably 1 to 20% by weight based on the dry weight of the web.

The heat-fusible fibers can be mixed to form a heat-fusible nonwoven fabric. Examples of the heat-fusible fiber used include, for example, an untwisted continuous polyester type, a copolyester type,
Copolyolefin-based, copolyamide-based fiber bundles and the like are preferred, but polyester-based and copolyester-based fibers are preferred.Also, for the purpose of supporting the strength of the nonwoven fabric after bonding, at least two resins having different melting points are used. It is also very preferable to use side-by-side or core-sheath composite fibers. As for the mixing ratio, it is preferable that 1 to 30 wt% of the heat-fusible fiber is mixed with the main fiber.

In the case of blending the heat-fusible fibers, untwisted heat-fusible fibers are prepared, and as shown in FIG. After rubbing, the yarns are combined, charged by contact peeling charging, and both fiber bundles are charged and spread to a monofilament level, and then passed through an air gun and a hood as described above to be collected as a web. The two fiber bundles may be combined into one before the friction with the fixed friction element, but if two fibers are combined and then rubbed with the friction element, the two fibers may overlap during traveling. For this reason, the friction is not uniformly performed on each fiber, and it is difficult to uniformly mix the fibers in different opening states. Therefore, in order to perform the mixing more uniformly, the former is more preferable. Also, when the contact peeling charging is performed separately and the two fiber bundles are combined just before the air gun,
When sucked into the air gun, both fibers are guided as two distinct fibers, and this history appears even after passing through the air gun, making it difficult to obtain a uniform root fiber state. In the collected web, the polyvinyl alcohol-based continuous fiber bundle and the heat-fusible fiber bundle, which are the main fibers, are mixed very uniformly in a state where each fiber is opened to a monofilament without forming a single layer of each fiber. And deposit in a substantially non-oriented state. The mixed and collected web is bonded by thermocompression bonding to form a long-fiber nonwoven fabric made of polyvinyl alcohol-based fibers. Also in this case, the web to be collected may be a single layer or a multilayer.

[0014] The long-fiber nonwoven fabric comprising the polyvinyl alcohol-based polymer of the present invention can be easily processed by a spinning method of a dry method, a wet method, or a dry-wet method, in which the fiber bundle is easily opened and formed into a sheet. Can be obtained.
In addition, in the polyvinyl alcohol-based long-fiber nonwoven fabric thus obtained, each fiber is deposited in a substantially non-oriented state in the sheet, and the uniform basis weight of the sheet is obtained even at a low basis weight of about 20 g / m ^2. It is a nonwoven fabric with very good properties,
The basis weight change rate is usually 20% or less. The basis weight variation rate referred to here is the coefficient of variation (standard deviation divided by the average value) of the weight of a piece of 50 mm wide and 200 mm long continuously cut out of the obtained nonwoven fabric in the width direction multiplied by 100. And expressed in%. Further, the tensile strength ratio in the fabric longitudinal direction / cloth width direction of this nonwoven fabric is 0.5 to 1.5, and there is no anisotropy in mechanical properties. In particular, the one obtained by blending heat-fusible fibers is the conventional one. A fabric having a considerably lower basis weight and a higher strength than a polyvinyl alcohol nonwoven fabric of short fibers can be obtained. Further, the cloth has excellent tear strength and is used as a sheet or the like that requires strength.

[0015]

EXAMPLES Next, the present invention will be described with reference to specific examples, but the present invention is not limited to these examples.

Example 1 Using a polyvinyl alcohol having a degree of polymerization of 1700, spinning and drawing were carried out by a dry method, and a fiber bundle was wound up so as not to mix in a twist to obtain a continuous non-twisted multifilament fiber bundle of 1180dr / 200f. Dry this fiber bundle sufficiently and reduce the moisture content to 0.05 wt.
% And then, the absolute humidity of the ambient atmosphere _{0.009kg-H 2 O / kg-} dry
The air was adjusted to air, and friction and contact-separation charging and spreading were performed with a metal Nelson roll using the apparatus shown in FIG. After electrification and opening, the web is collected in a sheet form and then adhered and weighted using a 10 wt% emulsion of polyacrylate.
The sheet was 40 g / m ² . The charged voltage of the fiber bundle at the time of friction and contact peeling was 3.0 KV. Also, in the obtained sheet,
Each filament of polyvinyl alcohol was uniformly dispersed and randomly deposited in a non-oriented manner. The basis weight change rate of this sheet is 15.4% in the width (horizontal) direction and in the longitudinal (vertical) direction.
It was very uniform at 7.3%. Also, cut out the sheet into 5cm width, tension where the strength was measured, in the seat width direction 100g / cm / g / m ² longitudinally 93g / cm / g / m ²
And the strength ratio in the vertical and horizontal directions was almost one.

Example 2 Using polyvinyl alcohol having a degree of polymerization of 4000, the fiber was spun and stretched by a wet method and wound up in a non-twisted state to obtain a fiber bundle of 1260dr / 80f. Moisture content 0.1 wt% of the fiber, the surrounding atmosphere, absolute humidity _{0.01kg-H 2 O / kg-} dry air under friction, were performed contact release charging opening. At this time, untwisted low-melting polyester fibers 150dr / 72f were simultaneously subjected to fiber opening for adhesion, and both fibers were twisted after friction with the friction bar. After passing through an air gun and a hood, the web was collected. At this time, the polyvinyl alcohol fiber bundle was charged to 2.5 KV. The polyvinyl alcohol fiber and the adhesive fiber in the collecting sheet were mixed with each other at a monofilament level and were uniformly mixed. The collected web was thermocompressed by passing between a heated metal roll engraved on the surface and a heated metal roll having a flat surface to obtain a sheet having a basis weight of 70 g / m ² . The fiber filaments in the sheet were uniformly deposited in a non-oriented state. The basis weight change rate of this sheet is
They were 17% and 8% in the width direction and the longitudinal direction, respectively. The tensile strength of this sheet was 74.6, 62.5 g / cm / g / m ² in the width direction and the longitudinal direction, respectively.

Comparative Example 1 A test was carried out in the same manner as in Example 1 except that the moisture content of the polyvinyl alcohol fiber bundle was changed to 3.2 wt%. could not.

Comparative Example 2 A test was performed in the same manner as in Example 1 except that the absolute humidity at the time of the fiber opening test was adjusted to 0.02 kg-H ₂ O / kg-dry air. The charged voltage was 0.8 KV, which was slightly low, but charged, but the fiber bundle could not be spread to the monofilament level. Many unopened bundle fibers were observed in the collected web, and the dispersibility of the fibers was very poor. The variation in the basis weight of this sheet was 28.3% in the width direction and 14.2% in the longitudinal direction.

[0020]

According to the present invention, the polyvinyl alcohol-based long-fiber nonwoven fabric can be used to open the polyvinyl alcohol-based long fiber or the polyvinyl alcohol-based long fiber and the heat-fusible long-filament very finely to a monofilament level. It is a long-fiber non-woven fabric that is uniformly mixed and adhered with an adhesive resin or by thermocompression bonding of heat-fusible fibers. In this non-woven fabric, each filament is in a substantially non-oriented state. And has a feature that the sheet basis weight is very uniform. The polyvinyl alcohol-based long-fiber nonwoven fabric according to the present invention has a small mechanical anisotropy of the sheet, and has high strength with a relatively thin, low-weight fabric, compared to a conventional polyvinyl alcohol-based short-fiber nonwoven fabric,
It is used for applications such as reinforcing materials and cover sheets in the fields of industrial materials and agricultural materials.

[Brief description of the drawings]

FIG. 1 is a schematic view of a defibrating device used in the present invention.

FIG. 2 is a schematic view of an apparatus used for producing a continuous filament web in the present invention.

FIG. 3 is a side view of the apparatus of FIG. 2;

FIG. 4 is a schematic diagram of a defibrating device used for blending heat-fusible fibers in the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Polyvinyl alcohol-based non-twisted continuous fiber bobbin 2 Heat-fusible non-twisted continuous fiber bobbin 3 Non-twisted continuous fiber bundle before defibration 4 Tensioning device 5 Guide 6 Fixed friction element 7, 7a Metal Nelson roller 8 Elastomer roll 9 Belt Voltage measurement position 10 Continuous fiber bundle after defibration 11 Air gun 11a Compressed air inlet 12 Side gun 12a Compressed air inlet 13 Hood 14a Hood inlet width 14b Hood outlet width 15 Collection net 16 Collection web 17 Suction device

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-63-145465 (JP, A) JP-A-51-112980 (JP, A) JP-A-1-280060 (JP, A) JP-A 62-145 170570 (JP, A) JP-A-55-93863 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) D04H 3/02 D04H 3/00

Claims (2)

(57) [Claims] 1. A continuous filament of polyvinyl alcohol.
The open fiber is opened by charging, and the opened fiber bundle is passed through an air gun.
To be opened in a substantially monofilament form
Deposited in a state of orientation and stabilized by adhesive resin
In the method of manufacturing a long-fiber nonwoven fabric, before charging and spreading
The moisture content of the filament fiber of
Humidity _{0.010kg-H 2 O / kg-} dry air below atmosphere smell
So that the absolute value of the charged voltage of the fiber bundle is 0.5 KV or more.
Perform the electrification opening process and transfer the opened fiber bundle to the air gun.
Gradiently narrows from the entrance located directly below to the exit
Blown into the hood into
Set the tensile strength ratio in the hand direction / cloth width direction to 0.5 to 1.5.
Polyvinyl alcohol-based long-fiber nonwoven fabric characterized by the following:
Manufacturing method. 2. A continuous filament of polyvinyl alcohol.
Fiber and thermo-adhesive continuous filament fiber by electrification
Spread and pass both spread fiber bundles through an air gun,
It is opened in a monofilament shape and deposited in a non-oriented state,
The shape is reduced by heat-sealing the heat-fusible continuous filament fibers.
In the method for producing a long fiber nonwoven fabric that has been standardized,
1.5% moisture content of filament fiber before electrification opening process
It follows and, following absolute humidity _{0.010kg-H 2 O / kg-} dry air
Under the atmosphere, the absolute value of the charged voltage of the fiber bundle is 0.5KV or less.
Perform the charge opening process so that it is on top, and open fibers
The bundle is moved from the entrance provided just below the air gun to the exit.
By blowing into the hood that was once narrowed
The tensile strength ratio of the nonwoven fabric in the fabric longitudinal direction / cloth width direction is set to 0.
Polyvinyl alcohol having a ratio of 5 to 1.5
Manufacturing method of non-woven long fiber nonwoven fabric.