JPS59157362A - Production of nonwoven comprising polyurethane elastic filament - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a nonwoven fabric made of polyurethane elastic filaments and a method for producing the same.

Various types of nonwoven fabrics have been proposed and put into practical use in many fields, but most of these nonwoven fabrics are made of non-elastic polyester, polyamide, or polyolefin fibers that do not have rubber-like elasticity. and
Nonwoven fabrics made of highly elastic fibers such as rubber or polyurethane have not been put to practical use.

The production of nonwoven fabric by melting an organic polymer material, such as nylon, and stretching it with a gas flow was disclosed in Japanese Patent Publication No. 41-78.
Although it is described in No. 83, polyurethane is only shown as an example of an organic polymer material. When attempting to produce nonwoven fabric using polyurethane using this method, it is necessary to raise the melting temperature to lower the melt viscosity of the polyurethane elastomer, which promotes thermal decomposition of the polyurethane elastomer and satisfies the spinning operation. It is difficult to implement this method. Furthermore, if a plasticizer or a low molecular weight polymer is used to lower the spinning temperature, a nonwoven fabric with unsatisfactory performance with poor strength and elongation is obtained.

As another method for producing a nonwoven fabric made of a polyurethane elastic material, Japanese Patent Laid-Open No. 52-81177 proposes dry spinning a polyurethane elastic material to form a nonwoven fabric.

However, since this method uses a solvent, removal and recovery of the solvent is required, which is extremely disadvantageous economically.

At present, there is no known method for industrially advantageous production of nonwoven fabrics made of polyurethane elastomers.

Under these circumstances, the inventors of the present invention have conducted intensive research and study on the production of nonwoven fabrics made of polyurethane elastic fibers, and have completed the present invention.

An object of the present invention is to provide a nonwoven fabric made of polyurethane elastic filaments, and another object of the present invention is to provide an industrially advantageous method for manufacturing such a nonwoven fabric by a melt spinning method.

The method of the present invention involves adding a polyisocyanate compound to a molten thermoplastic polyurethane elastomer, kneading it, and then ejecting the filament spun out from the pores along with a high-speed air stream, depositing and collecting it in a sheet form. Features.

As the polyurethane elastomer applied to the present invention, known segmented polyurethanes can be used, but melt-spun thermoplastic polyurethane is particularly suitable. Such a polyurethane elastomer is made of a low melting point polyol with a molecular weight of 500 to 6,000, such as dihydro[l-oxypolyether, dihydroxypolyester, dihydroxypolycarbonate, dihydroxypolyester amide, etc.] and an organic diisocyanate-1- with a molecular weight of 500 or less, such as p, p
'-diphenylmethane diisocyanate, tolylene diisocyanate, isoborone diisocyanate, hydrogenated diphenylmethane diisocyanate, xylylene diisocyanate, 2,6-diisoester methyl caproate, hexamethylene diisocyanate, etc. and molecular weight 50
Zero or less chain extenders, such as glycols, amino alcohols, or trios? It is a polymer obtained by reacting with alcohol. Among these polymers, particularly good are polyurethanes using polytetramethylene glycol, poly.epsilon.-caprolamine, or polybutylene adiperine as the polyol. When polyethylene glycol is used as a polyol, it improves hydrophilicity and is therefore used for special purposes.

Moreover, p,p'-diphenylmethane diisocyanate is suitable as the organic diisocyanate.

Further, as the chain extender, p,p'-bishydroxyel-1-oxyhenzene and 184-butanediol are suitable.

The polyisocyanate compound used in the present invention is preferably a compound having at least two isocyanate groups and has an average molecular weight of 400 or more. molar amount of molecule 1500), can be synthesized by reacting the organic diisocyanate below. At this time, a compound having three or more hydroxyl groups may be used as the polyol. Also used are organic diisocyanate dimers. Suitable polyisocyanate compounds include bolite 1-ramethylene glycol having a molecular weight of 500 to 2000 and having hydroxyl groups at both ends, polycaprolactone,
Alternatively, there may be mentioned a compound in which p,p'-diphenylmethane diisocyanate-1- is added to polybutylene adibe-1- in a double molar amount.

The amount of the polyisocyanate compound added is preferably 5 to 30% by weight, particularly preferably 10 to 20% by weight. The amount added varies depending on the type of polyisocyanate compound used, but if the amount added is small, the intended physical performance of the polyurethane nonwoven fabric will be insufficient and the effect of improving spinning operability will be small. Moreover, if the amount added is too large, non-uniform mixing and a ring of decreased yarn quality tend to occur, and the spinning operation becomes unstable, which is not preferable.

The molecular weight of the polyisocyanate compound used in the present invention is usually 400-12 or more, preferably 800 to 3,000. The molecular weight of the polyisocyanate compound applied to the present invention is the apparent molecular weight calculated from the isocyanate group weight measured by amine titration.

The nonwoven fabric made of polyurethane elastic filaments of the present invention is manufactured by adding ζ to the above-mentioned thermoplastic polyurethane in the manufacturing process.
After forming the fiber, the polyisocyanate compound reacts to form crosslinks, so its properties are completely different from those of the thermoplastic polyurethane elastomer used as a raw material, and it cannot be remelted. It is also insoluble in solvents such as dimethylformamide or tetrahydrofuran at room temperature.

Therefore, the nonwoven fabric of the present invention has high strength and excellent stretch recovery properties, and exhibits performance that has not been achieved conventionally. The polyisocyanate compound used in the method of the present invention not only improves the physical properties of the resulting nonwoven fabric, but also has the effect of lowering the melt viscosity of the polyurethane elastomer during the spinning process, making it possible to lower the spinning temperature. It becomes easy to avoid thermal decomposition of the polyurethane elastomer, and spinning operability is improved. In addition, since the polyurethane elastic fibers deposited as a non-woven fabric tend to adhere to each other, it becomes easy to firmly bond the non-woven fabric without using an adhesive by pressing the non-woven fabric, as will be described later.

The production of the nonwoven fabric of the present invention is preferably carried out using a spinning device equipped with a section for melt extruding the thermoplastic polyurethane elastomer, a section for adding and mixing the polyisocyanate compound, and a spinning section for the nonwoven fabric. . As such a spinning device, a known device used for adding a modifier during spinning can be used. Further, as the spinning head for nonwoven fabric, any known shape can be used, but a spinning head equipped with a nozzle for discharging molten polymer and slits on both sides of the nozzle for discharging heated inert gas is particularly suitable. Such a spinning head is described, for example, in Japanese Patent Publication No. 41-7883. For the part where the polyisocyanate compound is added to and mixed with the molten polyurethane, it is possible to use a kneading device having a rotating part (although it is more preferable to use a mixing device having a stationary kneading element). A known mixing device having a static kneading element can be used.The shape and number of elements of the static kneading element differ depending on the conditions of use, but It is important to ensure that the mixture is sufficiently mixed before it is discharged from the spinneret.

An example of an embodiment of the present invention will be described below.

Thermoplastic polyurethane elastomer from the hopper)
is supplied, heated and melted in an extruder. Melting temperature is 190~
A range of 230°C is preferred. On the other hand, the polyisocyanate compound is melted at a temperature of 100"C or less in a supply tank and degassed in advance.

If the melting temperature is too high, the properties of the polyisocyanate compound tend to change, so it is preferable that the melting temperature is as low as possible within the melting range, and a temperature between room temperature and 100° C. is used. The molten polyisocyanate compound is measured using a metering pump, filtered if necessary with a filter, and added to the molten polyurethane at a meeting point provided at the tip of the extruder. The polyisocyanate compound and polyurethane are kneaded using a kneading device having a static kneading element. This mixture is metered by a counting pump and introduced into the spinning head. Although the spinning head may be a conventional device for spinning nonwoven fabrics, it is preferable to design the spinning head to have a shape that minimizes the retention area of the mixture as much as possible. After removing foreign matter with a filter medium such as a wire mesh or glass beads in a layer provided in the spinning head if necessary, the mixture is discharged from a nozzle arranged in a row, and heated at high speed ejected from Surin I. It is deposited and collected on a net that is stretched and moved by air currents. The web collected on the net is immediately pressed with a roller, if necessary, and taken off as a nonwoven fabric.

The nonwoven fabric of the present invention usually has fibers with a diameter of 30 microns or less, an apparent density of 0.3 g/cJ or less, a cutting elongation of 200% or more, and a times at 100% elongation (9% of 90% or more). It has excellent breathability, stretch recovery, and heat retention, and is extremely flexible, so it can be used as filling for sportswear and composite materials that require stretchability, heat retention, and breathability, as well as interlining, reinforcing materials, and other materials for various clothing. It is useful for stretch tapes, strings, etc. Also, because it has the ability to fit various shapes and has cushioning properties, it has not been previously available in fields where conventionally known nonwoven fabrics are used, such as packing materials, fillers, and molding machines. You can get excellent results.

The present invention will be explained below with reference to examples.

Example ■ Polytetramethylene glycol 555 with a hydroxyl value of 102
0 parts, 500 parts of 1,4-bis(β-hydroxyjetoxy)henzene, and 1960 parts of p, p'-diphenylmethane diisocyanate were mixed in a kneader, and the mixture was heated at 85°
Boliure powder is heated to C.

Got tan. This was molded into pellets using an extruder. Concentration 1g/100 in dimethylformamide at 25°C
The relative viscosity of cc was 2.01.

On the other hand, 1000 parts of Volite 1 heramethylene glycol having a hydroxyl value of 112 and 500 parts of p,p'-diphenylmethane diisocyanate were reacted at 80°C for 30 minutes to obtain a viscous polyisocyanate compound.

The isocyanate group content of the sample was 5.60%.

Using the polyurethane elastomer pellets and polyisocyanate compound thus obtained as raw materials, heated air is injected onto both sides of nozzles lined up with an extruder equipped with a kneading section consisting of a polyisocyanate compound supply device and a static kneading element. A non-woven fabric was made using a spinning head with slits.

Table 1 shows the properties of the appropriate spun yarn and the obtained web when the amount of polyisocyanate compound added is changed while the discharge amount per nozzle is kept constant at 1.75 g/m t n. Met.

Claims (1)

[Claims] It is characterized by adding and kneading a polyisocyanate compound to a molten thermoplastic polyurethane elastomer, and then injecting the filament I spun out from the pores along with a high-speed air stream, depositing and collecting it in a sheet form. A method for producing a nonwoven fabric made of polyurethane elastic filaments.