JPS5837430B2 - Polyvinyl alcohol - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing spunbond nonwoven fabrics using a polyvinyl alcohol (hereinafter referred to as PVA) melt spinning method, including water-soluble or water-swellable spunbond nonwoven fabrics, high-temperature heat treatment, and binder treatment. The present invention provides a method for producing a spunbond nonwoven fabric that is free from damage to texture due to adhesion.

Traditionally, the wet spinning method for PVA-based synthetic fibers has been used.
Dry or semi-melt spinning methods are widely known, but wet spinning requires adjustment of the coagulation bath. Washing. There are many problems in process control such as drying, and it has been difficult to increase the spinning speed due to the nature of the spinning solution itself.

In addition, the dry spinning method or semi-melt spinning method using a concentrated solution containing water as a bath and some plasticizers is heated at 100°C.
If this is done above, foaming occurs, which deteriorates the spinnability, and the water must be evaporated to dryness, which lengthens the drying time, which naturally limits the spinning speed.

On the other hand, regarding the PVA melt spinning method, Patent No. 41372
No. 5 is known, but it is clear that in this method, the viscosity of the discharged melt is extremely high and the spinnability is poor, making high-speed spinning difficult.

Regarding high-speed spinning of PVA, Japanese Patent Application Laid-Open No. 473212
No. 8 describes PVA with an average degree of polymerization of 300 to 3000.
A method has been proposed in which a plasticizer with a weight range of 80% by weight is added and the product is melt-spun with a total ash content of 0.4% by weight or less, and then taken up by a jet stream. Since a plasticizer is used, this causes a decrease in the quality of the thread, and even if the plasticizer is extracted with water or methanol, voids are formed after the extraction, which also leads to a decrease in the quality of the thread.

As described above, various methods are known for spinning PVA-based synthetic fibers, but in all of these methods, the spinning speed is naturally limited by the spinnability, and high-speed spinning is impossible. Average degree of polymerization with addition of plasticizer of 80% by weight: 30
PVA of 0 to 3000 could only be spun at high speed under special conditions.

In particular, high-speed spinning using a suction jet is used for polyamide.
polyester. Although it is generally used for melt-spinning polymers such as polyolefins, it is difficult to apply such high-speed spinning methods to PVA, which cannot be melt-spun. The adoption of a high-speed spinning method for melt-spinning PVA that does not require a plasticizer was unforeseen in the prior art.

Moreover, water-soluble or water-swellable PVA fibers are widely used in the production of staple fiber nonwoven fabrics due to their special properties; This was unexpected since it is a resin that is inherently difficult to melt under heat.

In addition, spunbond nonwoven fabrics made of thermoplastic fibers are
In order to improve its mechanical performance, the constituent fibers were bonded together by heat and pressure, or they were bonded together using a binder. However, in the former method, the constituent fibers are heat-treated at high temperatures, so the fibers are Not only does it shrink, but its original flexibility and feel are impaired, and the latter method also has the disadvantage that the feel is impaired by binder adhesion.

As a result of research into various high-speed spinning methods for PVA using a bow jet that does not require water or plasticizers, the present inventor has found that:
We have completed the present invention by discovering that a specific PVA can be spun at a much higher speed than conventional spinning methods, and that the resulting fibers have excellent performance in the form of non-woven fabrics.

That is, in the present invention, a group of filaments obtained by melt-extruding anhydrous PVA having an average degree of polymerization of 50 to 300 and a residual acetic acid group width of 15 to 80 moles is pulled together singly or with filament groups of other fibers, or separately by a suction jet. This is a method for producing a PVA-based fiber non-woven fabric, which is characterized in that the PVA-based non-woven fabric is sprayed onto a non-woven sheet forming surface using a jet of air.

The present invention will be explained in detail.

The PVA used in the present invention has an average degree of polymerization of 50 to 300 and a residual acetic acid group of 15 to 80 moles.

Such PVA may, for example, have a polymerization temperature of 20 xi
Polyvinyl acetate was polymerized in an alcohol having a chain transfer constant of 0-' or more to an average degree of polymerization of 50-300. After heating to expel the solvent, the polyvinyl acetate was mixed and dissolved in anhydrous methanol, and an alkali was added. In addition, it can be easily produced by deacetating it.

If the average degree of polymerization of PVA is lower than 50, high-speed spinning is impossible because the spinnability decreases;
If it exceeds the above range, the melting temperature and melt viscosity will become high, and the difference between the melting temperature and the decomposition temperature will be small, and decomposition will occur at the same time as melting, resulting in a decrease in spinnability, making it impossible to apply it to the bird's-speed spinning of the present invention.

On the other hand, when the residual acetate group of PVA is lower than 15 molar width, the intermolecular force due to the increase in the hydroxyl group of PVA becomes stronger.
It becomes difficult to melt by heat, resulting in a decrease in stringability, and conversely, if the residual acetic acid group exceeds 80 molar width, the tackiness of the molten fiber increases and adhesion occurs to the spun fiber, making it impossible to apply it to the present invention.

For these reasons, the PVA applicable to the present invention needs to have an average degree of polymerization of 50 to 3000 and a residual acetate group of 15 to 80 mol %.

In the present invention, after sufficiently drying the specific PVA under reduced pressure at an appropriate temperature, it is supplied to a spinning machine having a spinning head maintained at a predetermined temperature, and the melt is spun from the spinneret to form a filament. The formed filaments are passed through a suction jet device provided below the spinneret, where a high-velocity jet stream is applied, and the propulsive force is used to index the filaments in the F direction. A nonwoven fabric is formed by uniformly spraying and depositing a jet stream ejected from a suction jet device onto a nonwoven sheet forming surface, which is a collection device.

The suction jet device used in the present invention is disclosed in, for example, Japanese Patent Publication No. 37-4993 or Japanese Patent Publication No. 41-78.
Conventionally known devices such as those described in Japanese Patent No. 83 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.

The device that applies this jet airflow may be selected appropriately from the flow region where the filament has not yet been defined immediately after spinning to the region where the filament has completely cooled and solidified and has reached the fiber form. Air at about room temperature or dry heated air may be supplied to a jet device, and heat treatment and steam treatment may be performed subsequent to or simultaneously with the index stretching by a jet stream.

The PVA melt extrusion of the present invention allows fibers with a single filament fineness of 30 denier or less to be spun at a high speed of 1000 m/min or more and at a wide range of spinning speeds. It is preferable to set the speed to 0.1 to 5.09/min from the standpoint of spinnability.

In the present invention, the fibers drawn by the jet stream are uniformly sprayed onto a non-woven sheet-shaped surface by the jet stream to form a web in which continuous filaments are deposited in a random loop. PVA-based polymers are prepared by spraying ice gas on the wet cloth obtained in this way, dissolving a portion of the PVA in the bath, and then crimping it, and collecting the ejected fibers in an unsolidified sheet form. A spunbond non-woven fabric of fibers can be formed.

The present invention is directed to a method in which a group of filaments obtained by melting and extruding the specific PVA is taken up by a high-speed air current, and the filaments are uniformly sprayed and deposited on a non-woven sheet forming surface by a blowing air current. The group may be used alone or in combination with filament groups of other fibers,
Furthermore, two or more types of filament groups may be taken up by separate suction jets and uniformly sprayed and deposited on the same non-woven sheet forming surface using a blowing air flow.

Therefore, according to the method of the present invention, it is possible to produce a spunbonded nonwoven fabric made of the PVA filament group alone, as well as a spunbonded nonwoven fabric made of a mixture of the PVA filament and filaments of other fibers.

At this time, if a nonwoven fabric is formed using PVA alone having a residual acetate group of 15 to 40 moles, a nonwoven fabric that is soluble in cold water will be obtained.If a nonwoven fabric is formed using PVA alone having a residual acetic acid group of 40 to 80 moles, it will be soluble in water. A water-swellable nonwoven fabric that does not completely dissolve is obtained.

Water-soluble non-woven fabrics are used, for example, as base fabrics for chemical lace, and water-swellable non-woven fabrics are used, for example, in diapers, dish towels, etc. due to their water-absorbing properties.

In addition, since the raw material PVA for both water-soluble and water-swellable nonwoven fabrics is heat-meltable and adhesive, it is possible to insert them between nonwoven fabrics and woven fabrics made of various fibers and heat-seal them to create a laminate. be.

In addition, when a specific PVA filament group and a filament group of other fibers are aligned and supplied to a suction jet device to form a nonwoven fabric, or a specific PVA filament group and a filament group of other fibers are supplied to separate suction jet devices. When a nonwoven fabric is formed by
VA filament itself exhibits adhesive properties with water or heat (200°C or less), so even if the fibers other than PVA that make up the nonwoven fabric are difficult to heat and press, or the texture of the nonwoven fabric will be significantly damaged by heating. Even in the case of easy-to-use fibers such as polyester, a strong spunbond nonwoven fabric can be produced simply by heat compression at a low temperature of 200° C. or less or by sprinkling water vapor. There is no damage to the texture that typically occurs due to high-temperature pressure bonding or binder adhesion.

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

Example 1 Chip-like PV with average degree of polymerization of 76 and residual acetic acid group of 31 mol%
After drying A under reduced pressure at 50°C for 24 hours, screw diameter 137717A screw length 3 15 m'll
It was introduced into the supply port of the extruder L, and the supply port was made into a drying nitrogen atmosphere, and then melted, and the spinning head temperature was 140'C and the pore diameter was 0.
．． 577X77! , 4.8 9/mi from the s hole nozzle
rM7) Perform extrusion at a discharge rate, then
P by the suction jet device set at crrL position.
A jet stream is applied to the VA discharged filament, and the spinning speed is approximately 4.
The material was taken up at a speed of 0.000 m/min, and the suction jet device was not moved in a traversal motion at the above position, and a uniform web was obtained by spraying and depositing the material onto the wire-mesh-like non-woven sheet forming surface using a jet air flow.

The single fiber fineness of the fibers taken out from this web is approximately 0.
98~1.61 denier, strength 0.61~0.97L?
/d, and elongation l was 7.5 to 32%.

Next, this web was pressed with a heated roller at 140° C., and a cold water-soluble spunbond nonwoven fabric was obtained.

Example 2 PVA with an average degree of polymerization of 170 and a residual acetic acid group of 52 mol% was
The raw material was dried under reduced pressure at 0°C for 8 hours, the spinning head temperature was 160°C, and the discharge amount was 5.2L. Melt extrusion was carried out in the same manner as in Example 1, except that the spinneret was lower
(The suction jet device installed in 77it was moved in a traverse motion while the spinning speed was about 6,900 m/InIn, and the spinning speed was about 6,900 m/InIn, and the spinning was spun onto a wire gauze to obtain a uniform web.

The single fiber fineness of some of the fibers taken out was o. s ~1
．． 2-72-/l/, strength 0.65 to 1. 0
8 r/d, and the elongation ranged from 18 to 45.

The web thus obtained was treated with steam and dried under pressure to obtain a water-swellable nonwoven fabric.

Example 3 PVA with an average degree of polymerization of 275 and 74 mol% of residual acetic acid groups was
After drying at 0°C under reduced pressure for 24 hours, the screw diameter was 2.
07 /
Spinning head temperature 180°C, pore diameter 0.37n71L, 12
1 per hole from the hole spinneret. 8 Spinning at a discharge rate of 97 min, and spinning for about 9000 m while traversing the suction jet device installed 40 crn below the spinneret.
A uniform web was obtained by taking it off at a spinning speed of /mIH and depositing it on a wire gauze using a turbulent air flow.

The single fiber fineness of the fibers taken out from this web is 1
．． 2-2.0 denier, strength 1.02-1.84P/d
, the elongation was 28 to 70%.

After spraying water in a mist on the uniform web thus obtained, it was dried at 100'C to obtain a flexible water-swellable nonwoven fabric having a basis weight of about 40 P/d.

Example 4 Chip-shaped PVA having an average degree of polymerization of 138 and a residual acetate group having a molar width of 43 was dried at 50° C. under reduced pressure for 24 hours, and then melt-spun in the same manner as in Example 1.

On the other hand, nylon 6 resin with an average molecular weight of about 20,000 was supplied to an extruder with screw diameter D = 40 m711 ψ and L/D = 27, and the spinning head temperature was 250°C and the pore diameter was 0.577! Mistake 5
0 per hole from the Q-hole spinneret. 6. ! ? /min
The yarn was spun at a discharge rate of .

The spun fibers are combined with the PVA melt-spun fibers under a spinneret.
(Align at m, and use the suction jet device installed there to approx.
The fibers were spun at a spinning speed of 0 0 0 m/min, and were uniformly sprayed and deposited on a wire-mesh-like non-fibrous sheet forming surface to obtain a uniform web.

By pressing this web between rollers heated to 180°C, the fiber weight ratio of PV to Chiron 6 is reduced to approximately 0.1.
A 5/1 spunbond nonwoven fabric was obtained.

The nonwoven fabric thus obtained had a soft texture and good adhesion between fibers.

Example 5 The average degree of polymerization obtained in Example 3 was 170 and the remaining acetate groups were 52
Monofilament fineness 1.5 denier and strength 5.6L manufactured separately from mol% PVA filament? /d polyester filaments so that the weight ratio was 10/90, the filaments were taken up by a suction jet, and the filaments were uniformly sprayed onto a wire gauze using a jet of air to deposit them in the form of a web.

By passing this web between heated rollers at 180°C, a flexible and highly strong nonwoven fabric was obtained.

Claims (1)

[Claims] 1 A group of filaments obtained by melting and extruding anhydrous polyvinyl alcohol with an average degree of polymerization of 50 to 300 and a residual acetic acid group width of 15 to 80 moles is pulled together singly or with a group of filaments of other fibers, or separately taken up with a suction jet and sprayed. A method for producing a polyvinyl alcohol-based synthetic fiber nonwoven fabric, which comprises blowing and depositing a nonwoven fabric on a surface on which a nonwoven sheet is formed using an air flow.