JPS5836102B2 - Fushiyokufunoseizouhouhou - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a hydrophobic thermoplastic resin and polyvinyl alcohol (
This article relates to a method for producing spunbond nonwoven fabric by mixing it with PVA (hereinafter referred to as PVA), and it has hygroscopicity,
The present invention provides a method for producing spunbond nonwoven fabrics made of hydrophobic thermoplastic fibers having water absorbing properties, as well as spunbond nonwoven fabrics that are not damaged by high temperature heat treatment or binder adhesion.

Conventionally, methods for producing spunbond nonwoven fabrics from melt-spun hydrophobic thermoplastic resins have been widely known;
The nonwoven fabric obtained by this method is made of hydrophobic thermoplastic fibers, so even if it is required to have hygroscopicity and water absorption comparable to cellulose fiber for sanitary materials or underwear,
It was not possible to provide such properties.

Furthermore, spunbond nonwoven fabrics formed from hydrophobic thermoplastic fibers can be produced by heat-pressing to heat-fuse the structural fibers to each other, or by bonding the structural fibers to each other using a binder to improve the mechanical performance of the nonwoven fabric. However, the former method not only shrinks the fibers but also loses their original flexibility and texture due to the high-temperature heat treatment of the Guangwei fibers, while the latter method also causes the texture to be damaged due to binder adhesion. There were some drawbacks.

The present inventor has demonstrated that it is possible to impart the hygroscopicity and water absorption properties of PVA to hydrophobic thermoplastic fibers, and that they exhibit adhesive ability when heated at low temperatures or with water, similar to the binder fibers used in the production of short fiber nonwoven fabrics. It was determined that if the fibers could be obtained by high-speed spinning in the spunbond method, the problems of the conventionally known spunbond nonwoven fabrics could be overcome, and as a result of intensive research, not only could a specific PVA be mixed with a hydrophobic thermoplastic resin and spun. The present invention was completed by discovering that high-speed spinning is possible, and that it is possible to not only improve the hygroscopicity and water absorbency of hydrophobic thermoplastic fibers but also impart adhesive ability by changing the amount of PVA added. did.

That is, the present invention uses a hydrophobic thermoplastic resin and an average degree of polymerization of 5.
0-3001 residual acetate group 15-70 mol% (7)P
A group of filaments melted and extruded by mixing with VA can be pulled together singly or with a group of filaments of other fibers, or taken separately with a suction jet and sprayed and deposited on the surface of a non-woven sheet using a jet of air. This is a unique method for producing nonwoven fabric.

The present invention will be explained in detail.

The hydrophobic thermoplastic resin used in the present invention refers to generally known polymeric compounds such as polyester, polyamide, and polyolefin that can be melted into fibers.

In addition, in the present invention, the PVA to be mixed with the hydrophobic thermoplastic resin has an average degree of polymerization of 50 to 300, and a residual acetate group of 15
It refers to a heat-melting substance with a capacity of ~70 mol.

Such special PVA is produced by polymerizing vinyl acetate to an average degree of polymerization of 50 to 300 in an alcohol having a chain transfer constant of 20 x 10' or more at the polymerization temperature, for example.
It can be easily produced by expelling the solvent under heating, mixing and dissolving polyvinyl acetate in anhydrous methanol, and adding an alkali to deacetate the mixture.

In the present invention, a hydrophobic thermoplastic resin and PVA are mixed and melted and spun at high speed. However, when the average degree of polymerization of PVA mixed with the hydrophobic thermoplastic resin is higher than 300, the melting temperature of PVA is high; PVA is thermally decomposed and the melt viscosity also increases, making mixing melting and high-speed spinning difficult, and PVA with an average degree of polymerization lower than 50 is difficult to produce with good thermal stability. In some cases, thermal decomposition tends to occur, making it unsuitable for the purpose of the present invention.

Therefore, the average degree of polymerization of PVA applied to the present invention is 5.
It needs to be in the range of 0 to 300, especially 10
0-250 PVA is more preferred.

On the other hand, if the residual acetate group of PVA is lower than 15 molar ratio, the intermolecular force due to the intermolecular and intramolecular hydrogen bonds of the hydroxyl group becomes strong, making it difficult to heat melt, similar to the case where the average degree of polymerization of PVA is 300 or more. , it becomes difficult to mix melt-spinning with a hydrophobic thermoplastic resin, and if the residual acetate group of PVA exceeds 70 molar ratio, the water swelling property of PVA decreases, and even when mixed with a hydrophobic thermoplastic resin, it does not absorb enough moisture. It is unsuitable because it cannot impart properties and water absorption properties.

Therefore, the amount of residual acetic acid groups in PVA needs to be in the range of 15 to 70 moles, and particularly preferably 20 to 60 moles.

In the present invention, the hydrophobic thermoplastic resin and the specific PVA may be mixed in chips that have been melt-mixed in advance, or may be mixed in the form of chips before or during melting, but the mixing ratio is When producing a spunbond nonwoven fabric using only spun fibers, it is desirable that the weight ratio of PVA and hydrophobic thermoplastic resin be in the range of 5:95 to 50:50, and it is preferable that the weight ratio of PVA and hydrophobic thermoplastic resin be in the range of 5:95 to 50:50. When manufacturing a bonded nonwoven fabric, it is desirable that the weight ratio of PVA and hydrophobic thermoplastic resin be in the range of 50:50 to 85:15.

By making such a mixing ratio, in the former case, a thermoplastic fiber spunbond nonwoven fabric having hygroscopic and water absorbing properties is obtained, and in the latter case, a spunbond nonwoven fabric is formed.
By applying low-temperature heat treatment at 0° C. or lower or applying pressure after spraying with steam, a nonwoven fabric with excellent texture can be obtained.

During mixed melt extrusion, the hydrophobic thermoplastic resin and the PV
Before spinning, A is sufficiently dried under reduced pressure at an appropriate temperature, and then supplied to a spinning machine maintained at a predetermined spinning head temperature, and the mixed melt is spun from a spinneret to form a filament. It is necessary.

In the present invention, the mixed spun fibrous body obtained in this manner is passed through a suction jet device provided below the spinneret, where a high-velocity jet stream is applied, and the fibrous body is spun using the propulsion force. It is indexed downward and is sprayed and deposited uniformly on the non-woven sheet-shaped surface with the jet stream ejected from the suction jet device.

As a suction jet device used at this time, for example, Japanese Patent Publication No. 37-4997 or Japanese Patent Publication No. 41-7
A known device such as that disclosed in Japanese Patent No. 883 can be used.

In addition, air, nitrogen gas, carbon dioxide gas, etc. are usually used as the gas serving as a medium for the jet stream, but any other active or inert gas can be used depending on the purpose.

When using a gas containing oxygen, it is advisable to add a small amount of a phosphoric acid compound such as phosphoric acid or phosphorous acid to the PVA in order to prevent coloration due to oxidative decomposition of the PVA.

The device that applies this jet airflow may be appropriately selected from the flow area where the filament has not yet been fixed immediately after spinning to the area where the filament has completely cooled and solidified and reached the fiber form, and the suction jet Heat treatment and steam treatment may be performed subsequent to or simultaneously with index stretching using a jet stream by supplying air at about room temperature or a heated gas such as dry hot air, water vapor, or water vapor saturated air to the apparatus.

In the method of the present invention, fibers with a single yarn weave of 30 denier or less are
It is possible to spin at a high speed of 0.00 m/min or more and over a wide range of spinning speeds, but in this case, the discharge rate from each hole of the spinneret is 0.1 to 5.0 m/min. Ogl content is more desirable than spinnability.

In the present invention, the fibers drawn by such spinning and jet stream are formed into a sheet-like web in which continuous filaments are deposited in random loops, and the web thus obtained is sprayed with water vapor or A spunbond nonwoven fabric can be formed by force-thermocompression or by collecting the ejected fibers in a sheet form in an unsolidified state.

In the method of the present invention, a group of filaments mixed and melted and extruded with a hydrophobic thermoplastic resin or a specific PVA is taken up by a high-speed air stream, and is uniformly sprayed onto a non-woven sheet-shaped surface by a jet air stream. At this time, the filament group taken up by a high-speed air current may be a mixed spun fiber alone or a group of filaments of other fibers, or two or more types of fibers may be collected by separate suction jets. Since it can be uniformly sprayed and deposited on the same non-woven sheet shape or surface by taking up and blowing air, it can be used for spunbond nonwoven fabrics made of mixed spun fibers alone, as well as spunbond nonwoven fabrics mixed spunbond fabrics made of mixed spun fibers and other fibers. can also be manufactured.

At this time, when a spunbond nonwoven fabric is produced solely from mixed spun fibers in which the mixing ratio of PVA and hydrophobic thermoplastic resin is 5:95 to 50:50 by weight, the resulting nonwoven fabric has hygroscopic and water absorbing properties. It can also be used for sanitary materials, underwear, etc., and spunbond nonwoven fabrics made of mixed spun fibers and other fibers with a ratio of 50:50 to 85:15 can be bonded by low-temperature heat compression at 200°C or less or by spraying water vapor. Since the fibers can be bonded together simply by doing this, it is possible to obtain an excellent spunbond nonwoven fabric that does not suffer from damage to its texture due to high-temperature compression bonding or binder treatment.

Hereinafter, the present invention will be explained in more detail with reference to Examples.

Example 1 Average degree of polymerization 1 4 0 sufficiently dried under reduced pressure in advance
, 80 parts by weight of nylon 6 resin having an average molecular weight of about 20,000 was added to 20 parts by weight of PVA containing 27 moles of residual acetic acid groups, and the mixture was fed to the feed port of an extruder having a screw diameter of 208 and a screw length of 4448. A dry nitrogen atmosphere was used.

Spinneret temperature was 240°C, hole diameter was 0.3M, and spinning was carried out from a 12-hole spinneret at a discharge rate of 897 minutes per hole, and spinning was carried out at approximately 9000 m/minute while making a traverse motion using a suction jet device installed at 40 cIrL below the spinneret. A uniform web was obtained by spraying at a high speed onto a wire mesh, and this was thermocompressed to obtain a nonwoven fabric having a basis weight of 30 g/m2.

The tensile strength of this nonwoven fabric is 6.5Ky/5cm. The elongation is 80.3% and the weft tensile strength is 7. 4 KP/5
crrL and elongation of 82.5%, which were not significantly different from the nonwoven fabric obtained under the same conditions using nylon 6 alone.

The moisture content of the nonwoven fabric of the present invention at 20°C and 65% RH is 7,
It was 1%, whereas that of the nonwoven fabric made of nylon 6 alone was 4.2%, which clearly showed that the water absorbency was improved.

Example 2 30 parts by weight of sufficiently dried PVA with an average degree of polymerization of 250 and a residual acetic acid group of 58 mol % and an average molecular weight of about 8000
0. Added 70 parts by weight of polypropylene with a melting point of 165°C,
Vented extruder (screw diameter D40, L/D=2
7), and the spinning head temperature was 170°C, the hole diameter was 0.3 mm, and 1.0 mm per hole was fed from a 50-hole spinneret. 3 0
Spinning was carried out at a discharge rate of 1 gl.

A suction jet device installed at 100 crrL below the spinneret was moved in a traversal motion, and the spinning speed was about 6000 m/min, and the web was sprayed onto a wire mesh to form a uniform web, which was then thermocompressed to form a nonwoven fabric with a fabric weight of about 3097 m'. Obtained.

The water absorbency of this nonwoven fabric at 20° C. and 65 SRH was 3.8, which was 0.1% for the nonwoven fabric made only of polypropylene, but the water absorption was greatly improved.

There was no significant difference in the mechanical strength of the nonwoven fabrics.

Example 3 40 parts by weight of nylon 6 resin having an average molecular weight of about 20,000 was added to 60 parts by weight of sufficiently dried PVA having an average degree of polymerization of 170 and a residual acetic acid group of 38 mol, and melt spinning was carried out in the same manner as in Example 1.

On the other hand, the above-mentioned nylon 6 resin was spun at a spinning head temperature of 250°C, a hole diameter of 0.3#, and a spinneret of 60 holes at a rate of 1.89 mm per hole.
The spun filament was spun at a discharge rate of 7 minutes, and the spun filament was
VA/Nylon 6 mixed melt spun filament and both were aligned at 60 crfL below the spinneret, and the suction jet device installed there was traversed for about 9
The web was taken up at a spinning speed of 1,000 m/min and sprayed uniformly onto a non-woven sheet shaped like a wire mesh using a jet air stream to deposit a web.

After steam treatment, this was pressed between heating rollers at 100°C and dried to obtain a nonwoven fabric having a weight ratio of PVA-nylon mixed spun filament/nylon 6 filament of about 1/5.

The texture of the obtained nonwoven fabric was good, and it was
The moisture content under H was 6.8%, while the moisture content under nylon 6
That of the nonwoven fabric alone was 4.1%, and it was clear that the water absorption was improved.

Claims (1)

[Claims] 1 A group of filaments obtained by mixing and melt-extruding a hydrophobic thermoplastic resin and polyvinyl alcohol having an average degree of polymerization of 50 to 300 and a residual acetic acid group of 15 to 70 mols is used singly or with a group of filaments of other fibers, or separately by a suction jet. 1. A method for producing a nonwoven fabric, which comprises taking the nonwoven fabric in a vacuum cleaner, and spraying and depositing it onto a nonwoven sheet-shaped surface using a jet of air.