JPH0319952A - Nonwoven fabric of polyurethane elastic yarn - Google Patents

Abstract

PURPOSE:To obtain the subject nonwoven fabric having flexibility, stretchability and air permeability by laminating polyurethane elastic filament, prepared by melt spinning, in a specific state. CONSTITUTION:Polyurethane elastic filament prepared by melt spinning is opened, bonded, joined by heating at cross points of mutual fibers and bending resistance (mm) is set in a range shown by the formula 0.2x+10<=y<=0.2x+20 based on weight x (g/m<2>). Breaking strength of nonwoven fabric is >=0.4kg/cm based on 100g/m<2> weight and the prepared nonwoven fabric can be used for various purposes by itself.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a polyurethane elastic fiber nonwoven fabric having excellent flexibility, stretchability, and air permeability.

(Prior art and problems to be solved by the invention) A variety of nonwoven fabrics have been proposed and used in many fields, but most of these nonwoven fabrics are made of inelastic polyamides, polyesters, polyolefins, etc. Nonwoven fabrics made of highly elastic fibers such as polyurethane elastomer have not been put to practical use.

Several proposals have been made so far regarding nonwoven fabrics made of polyurethane elastic fibers.

For example, Japanese Patent Publication No. 43-26578 describes that a web made of short fibers of polyurethane elastic fibers is treated with aldehyde. However, the resulting nonwoven fabric does not have strong bonding between fibers, has large permanent set upon deformation, contains aldehyde, and is complicated to process.

Further, Japanese Patent Publication No. 43-26592 proposes subjecting a web made of short fibers of polyurethane elastic fibers to heat and pressure treatment. However, in the products obtained by this method, the bond between the fibers is not strong, and when this is strengthened, a film is formed on the surface layer, resulting in a hard texture. Furthermore, since the nonwoven fabric is heated under pressure after being made, the operation becomes complicated and uniform adhesion becomes difficult. Furthermore, JP-A-52-811
Publication No. 77 describes a method in which a polyurethane elastomer is dry-spun to form a web containing a solvent, and then the solvent is removed. is difficult to obtain, and nonwoven fabrics made from it are coarse and stiff. Moreover, dry spinning requires complicated equipment and operations.

Japanese Unexamined Patent Publication No. 54-147274 discloses a method for producing a nonwoven fabric with good texture and no pinholes by spraying fine droplets using the melt-blow method and then collecting them. Example 4 illustrates a polyurethane nonwoven fabric. By this method, the binhole (0.
Although it has become possible to produce a nonwoven fabric without polymer lumps (polymer lumps larger than 3 mm in diameter), the fibers do not bond with each other, perhaps due to the turbulence of the high-speed gas flow caused by the spraying of droplets and the uneven cooling of the fibers due to contact with the droplets. Problems remain in that fibers are fused together into bundles and large amounts of extremely thick fibers that are not thinned are mixed in, resulting in nonwoven fabrics that are inferior in texture and flexibility.

The present inventors completed the present invention as a result of research to eliminate such conventional defects. An object of the present invention is to provide a polyurethane elastic fiber nonwoven fabric having flexibility, stretchability, and air permeability. Another purpose is to appropriately change the fineness, cross-sectional shape, and fiber density of the fibers that make up the nonwoven fabric.
The object of the present invention is to provide an elastic nonwoven fabric that has performance according to the purpose of use and can be made into a variety of products by combining with fabrics such as inelastic nonwoven fabrics and knitted fabrics, or other molded products. A further object of the present invention is to provide a method for industrially and easily manufacturing polyurethane elastic fiber nonwoven fabric having excellent flexibility, stretchability, and air permeability.

(Means for Solving the Problems) The present invention is characterized in that melt-spun polyurethane elastic filaments are laminated without being substantially bundled, and the contact points of the laminated filaments are joined by the filaments themselves, and The bending resistance (y) is expressed by the general formula 0. 2 x +1 0≦y<0. 2 X +
20 (y is bending resistance (mm), X is basis weight (g/m")), and the breaking strength per basis weight of 100 g/m" is 0. It is a polyurethane elastic fiber nonwoven fabric with a weight of 4 kg/cm or more.

As the polyurethane elastic body constituting the nonwoven fabric of the present invention, a known melt-spuntable thermoplastic polyurethane elastic body is applied. Such a polyurethane elastomer is usually made of a low melting point polyol (e.g. dihydroxy polyether, dihydroxy polyester,
dihydroxypolycarbonate, dihydroxypolyesteramide, etc.) and organic diisocyanates with a molecular weight of 500 or less (for example, p,p'-diphenylmethane diisocyanate, tolylene diisocyanate, isophorone diisocyanate, hydrogenated diphenylmethane diisocyanate, xylylene diisocyanate. 2,6-diisocyanate methylcabroate, hexamethylene diisocyanate, etc.) and a chain extender (eg, glycol, amino alcohol, or triol) having a molecular weight of 500 or less. Among these polymers, particularly good are polyurethanes using polytetramethylene glycol, polycabrolactone, or polybutylene adipate as the polymer.

When polyethylene glycol is used as a polyol, its hydrophilicity improves, so it is used for special purposes. Moreover, as an organic diisocyanate, p. p'-diphenylmethane diisocyanate is preferred. Moreover, p+ p/-bishydroxyethoxybenzene and 1,4-butanediol are suitable as chain extenders.

The polyurethane elastomer is synthesized from a polyol, an organic diisocyanate, and a chain extender as described above, but the polyol component preferably used in the present invention is 65% by weight or more of the total weight, Particularly preferred is 68
% by weight or more.

If the content of the polyol component is low, the elongation and elongation recovery of the resulting nonwoven fabric will be low.

These polyurethane elastomers may contain plasticizers, pigments, stabilizers, and the like.

The nonwoven fabric of the present invention is a fabric in which polyurethane elastic filaments are spread and laminated over substantially the entire length of the yarn without joining.

If the monofilaments are joined in a bundled state without being opened, the flexibility of the nonwoven fabric will be significantly impaired. The diameter of the monofilament is usually 30 microns or less on average, preferably 25 microns or less on average, and particularly preferably 20 microns or less. The diameter of the monofilament may vary, but it is preferably 50 microns or less at most. As the fiber diameter of the monofilament increases, the nonwoven fabric becomes rough and stiff.

The cross-sectional shape of the polyurethane elastic fibers constituting the nonwoven fabric of the present invention can be various shapes such as circular, irregularly shaped, hollow, etc.
In terms of post-processability as a nonwoven fabric, sheet formability, and elasticity, a circular cross-section is preferred.

The nonwoven fabric of the present invention is a fabric in which polyurethane elastic filaments are laminated, and the contact points of the fibers constituting this laminate are joined by the fibers themselves.

Such a bonded state can be achieved by thermally fusing the polyurethane elastic fibers together. Methods using solvents or other adhesives improve the breathability of nonwoven fabrics,
Undesirable because it reduces flexibility. However, an adhesive may be used in combination without impairing these properties.

One of the important features of the nonwoven fabric of the present invention is its breaking strength. It has extremely high elongation and excellent elastic performance. This is because the performance directly reflects the performance of the polyurethane elastic fibers that make up the nonwoven fabric, and is not as good as conventional nonwoven fabrics made of nonelastic polymers or nonwoven fabrics made of polymers with poor elasticity such as polyester ether elastics. The performance is unparalleled. The nonwoven fabric of the present invention usually has a breaking elongation of 300% or more, preferably 500% or more.

Breaking strength varies depending on the thickness of the nonwoven fabric, but
Usually, it is 0.4 kg/cm or more per 100 g/m", preferably 0.6 kg/cm or more.

Also, the recovery rate at 10% elongation is usually 85% or more, preferably 90% or more.The strength of the nonwoven fabric.Elongation and elongation recovery rate vary depending on the adhesive strength of the contact points between the fibers that make up the nonwoven fabric. However, the fact that the nonwoven fabric of the present invention exhibits the above-mentioned strength, elongation, and elongation recovery rate indicates that the bonding at the contact points is sufficiently performed.

The greatest feature of the nonwoven fabric of the present invention is that it has extremely high flexibility. The bending resistance (JIS L-1096 45 degree cantilever method) of a nonwoven fabric increases as the basis weight of the nonwoven fabric increases, but the nonwoven fabric of the present invention increases the basis weight by
(g/m2), bending resistance is y (mm), 0. 2 x + 1 0≦y<0. 2 x +
It is in the range of 20. This feature is achieved by the physical properties of the polyurethane elastic body, the structure of the nonwoven fabric of the present invention as described above, and the small diameter of the constituent fibers. This is something that Webb could not have achieved.

Next, the method for manufacturing the nonwoven fabric of the present invention will be explained.

The thermoplastic polyurethane elastomer described above is melted and discharged from a spinneret using a spinning apparatus described in Japanese Patent Publication No. 41-7883, for example, with heated gas streams jetted from both sides of the nozzle (the heating temperature is lower than the polymer temperature). (preferably around the melting point of polyurethane) to thin the filaments.

The attenuated filaments are separated from the gas stream and deposited on a collecting device, such as a moving conveyor net, without being substantially focused. The stacked filaments are bonded together at their contact points by the filaments themselves in a stacked state due to their own heat. They may be bonded by heating and pressing using a roller or the like before or after being laminated on the collection device and cooled and solidified. In order to strengthen the bonding of the contact points between the filaments, the distance from the spinneret to the position where they are stacked on the collection device should not be too long, at most 1m, preferably 50cm.
It is as follows. Although it is possible to provide a gas flow guiding path between the cap and the collection device, there is no problem even if there is no gas flow guiding path.

The nonwoven fabric of the present invention uses the thermoplastic polyurethane elastomer described above as the polymer, but more preferably, a polyisocyanate compound is added to the molten polyurethane elastomer, kneaded, and then discharged from a spinning nozzle.

(Effects of the Invention) The nonwoven fabric made of polyurethane elastic fibers of the present invention has excellent elasticity. It is used alone for a variety of purposes due to its flexibility and breathability, but it can also be combined with other materials to create even more diverse products. Such materials include inelastic polymers such as polyester, nylon,
Synthetic fibers such as polyolefin and acrylic, or cellulose,
Examples include knitted fabrics, net fabrics, non-woven fabrics, and webs made of natural fibers such as wool. Furthermore, films such as polyurethane, foam sheets, etc. can also be used.

Such products are used as materials for various clothing such as sportswear and foundations that require elasticity, as well as interlining, filling, reinforcing agents, stretch tape, etc.
There are bands etc. In addition, it is a packing type because it fits various shapes, has cushioning properties, and has good shapeability. Useful as cushioning material, filler, and molding material. In addition, the unique friction coefficient and abrasion resistance of polyurethane elastomer can be utilized in various anti-slip applications such as shoe lining materials.

(Example) The present invention will be explained below with reference to Examples.

Note that various physical property values were measured by the following methods.

Breaking strength and elongation: JIS l096 sample with a width of 2 cm
According to
Stretch as n, and measure the strength and elongation per lcm width at break.

100% elongation recovery rate: Grasp a sample with a width of 2 cm and an interval of 5 cm
It is stretched 100% at a tensile speed of 10 cm/min, and immediately recovered to its original length at the same speed. Calculate the residual elongation rate l (%) from the recorded load-elongation curve and use the following formula to calculate 10
Calculate the 0% elongation recovery rate.

Bending resistance: Based on the 45° cantilever method of JIS L-1096.

Air permeability: JIS L-1096 Frazier type tester was used.

Example 1 5548 parts of dehydrated polytetramethylene glycol having a hydroxyl value of 102 (all parts below mean parts by weight) and 49 parts of 1,4-bis(β-hydroxyethoxy)benzene
9 parts in a jacketed seconder, and after thoroughly dissolving with stirring, maintain the temperature at 85°C, and add p
．． 1953 parts of p'-diphenylmethane diisocyanate was added and reacted. When stirring was continued, powdered polyurethane was obtained in about 30 minutes, which was formed into pellets using an extruder to form a polyurethane elastomer having a relative viscosity of 2.50 at a concentration of 1 g/100 cc measured at 25°C in dimethylformamide. Obtained.

The thus obtained pellets of polyurethane elastic material were used as raw materials, and the pellets were arranged in a row with a diameter of 0. Using a melt blow spinning device with a 8 mm nozzle having slits for injecting heated gas on both sides, the melting temperature was 245 °C, and the speed per nozzle was 0 per minute.
．． The polymer was discharged at a rate of 5 g, and air heated to 200"C was injected through the slit at a pressure of 3-5 kg/cm" to atomize it. The thinned filament was collected on a conveyor made of a 3o mesh wire mesh installed 25 cm below the nozzle, and then sandwiched between rollers to obtain a nonwoven fabric. This nonwoven fabric was made up of opened and laminated monofilaments of polyurethane elastic fibers, and the intertwining points between the filaments were joined together by fusion. The physical properties of this nonwoven fabric were as follows.

Fabric weight: 180g/m" Breaking strength: 1-Okg/c
m Breaking elongation 685% 100% elongation recovery rate 92% Bending resistance
54mm filament diameter 20 microns breathability 1 7 3 cm'
/cm''/see This nonwoven fabric is flexible, has high elasticity and breathability, and is therefore effective in combination with elastic fabrics for sports clothing and foundation applications.

Example 2 Polyurethane elastic fiber nonwoven fabrics of various basis weights were manufactured using the method of Example 1 by changing the polymer discharge amount and take-up speed. All filaments had diameters between 20 and 30 microns. The bending resistance of each nonwoven fabric increased as the basis weight increased, but all values satisfied formula (I). Immediately after being collected on a conveyor net, the material was pressed with a heated roll at 130°C, and the bending resistance value was further reduced.

Comparative Example 1 For comparison, commercially available polyurethane fiber (40 denier 4 filaments) was cut into 8 mm pieces, and the fabric weight was 12 mm using a paper machine.
A web with a weight of 0 g/m' was prepared and subjected to heating and pressure treatment at 150°C for 5 minutes, and its bending resistance was 76. Further, the bending strength of the sheet made by heating and pressing a 120 g/m'' filament diameter 50 microns at 150 DEG C. by lowering the ejection pressure of the heated air was 65.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram showing the relationship between basis weight (X) and bending resistance (y). Weight (9/rrl2)

Claims (1)

[Scope of Claims] Melt-spun polyurethane elastic filaments are stacked in a substantially unfocused manner, and the contact points of the stacked filaments are joined by the filaments themselves,
In addition, the bending resistance (y) is expressed by the general formula (I) 0.2x+10≦y<0.2x+20 (I) [y represents the bending resistance (mm), x represents the basis weight (g/m^2)] A polyurethane elastic fiber nonwoven fabric having a breaking strength of 0.4 kg/cm or more per area weight of 100 g/m^2.