JP2711257B2 - Method for producing polyurethane elastic fiber nonwoven fabric - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a polyurethane elastic fiber nonwoven fabric. [0002] Conventionally, various nonwoven fabrics have been proposed and used in many fields. Most of these nonwoven fabrics are composed of inelastic polymers such as polyamide, polyester and polyolefin. Nonwoven fabrics made of fibers having high elasticity such as polyurethane elastic materials have not been put to practical use. Several proposals have been made on nonwoven fabrics made of polyurethane elastic fibers. For example, JP-B-43-26578 describes that a web made of short fibers of polyurethane elastic fibers is treated with aldehyde. However, the obtained nonwoven fabric is not strong in bonding between fibers, has a large permanent set at the time of deformation, and contains aldehyde and is complicated in processing. Japanese Patent Publication No. 43-26592 proposes to heat and press a web made of short polyurethane elastic fibers. However, the fiber obtained by this method does not have a strong bond between fibers, and if the fiber is made stronger, a film is formed on the surface layer, resulting in a hard texture. In addition, since the heating is performed under pressure after the nonwoven fabric is produced, the operation becomes complicated, and uniform fixation becomes difficult. Further, Japanese Patent Application Laid-Open No. 52-81177 discloses a method of removing a solvent after forming a web in a state of containing a solvent in dry spinning of a polyurethane elastic body, but the fibers are stuck together due to dry spinning. Opened fibers are difficult to obtain, and nonwoven fabrics made therefrom are coarse and rigid. In addition, the apparatus and operation are complicated because of the dry spinning. [0004] The inventors of the present invention have completed the present invention as a result of research in order to eliminate such a conventional disadvantage. An object of the present invention is to provide a method for producing a polyurethane elastic fiber nonwoven fabric having flexibility, elasticity and breathability. The other purpose is to appropriately change the fineness, cross-sectional structure and fiber density of the non-woven fabric constituent fibers to have performance according to the purpose of use, and to fabricate non-elastic non-woven fabric or knitted fabric or other molded products. It is an object of the present invention to provide a method for producing an elastic nonwoven fabric which can be made into various products by a combination with the above. Still another object is to provide a method for industrially easily producing a polyurethane elastic fiber nonwoven fabric having excellent flexibility, stretchability and air permeability. According to the present invention, a substantially continuous filament obtained by melt-spinning a thermoplastic polyurethane elastic material, injecting a high-temperature gas stream after the melt-spinning, and thinning the resultant into a sheet is laminated. The laminated filaments are joined by heat fusion at the tangent melting point of the filaments. [0006] The polyurethane elastic fiber nonwoven fabric obtained by the method of the present invention having a basis weight 100 g / m ² per breaking strength 0.4
kg / cm or more. The polyurethane elastic fiber non-woven fabric,
Usually, the melt-spun polyurethane elastic filaments are laminated without being substantially bundled, and the filaments themselves are joined by heat fusion at the contact points of the laminated filaments, and the rigidity (y) is represented by a general formula. y <0.2x + 20 (where y represents bristles (mm) and x represents basis weight (g / m ² ))
It is excellent in flexibility, stretchability and air permeability in the range represented by. As the polyurethane elastic material constituting the nonwoven fabric, a known melt-spinnable thermoplastic polyurethane elastic material is applied. Such polyurethane elastomers usually have low molecular weight polyols having a molecular weight of 500 to 6000, such as dihydroxy polyether, dihydroxy polyester,
Dihydroxy polycarbonate, dihydroxy polyester amide, etc., and an organic diisocyanate having 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 methyl caproate , Hexamethylene diisocyanate, etc., and a chain extender having a molecular weight of 500 or less, for example, glycol, amino alcohol or triol. Among these polymers, particularly preferred are polyurethanes using polytetramethylene glycol or polyε-caprolactone or polybutylene adipate as a polyol.
If polyethylene glycol is used as the polyol, the hydrophilicity is improved, so that it is used for special applications. As the organic diisocyanate, p, p'-diphenylmethane diisocyanate is preferred. As chain extenders, p, p'-bishydroxyethoxybenzene and 1,4-butanediol are preferred. [0008] The polyurethane elastomer is synthesized from a polyol, an organic diisocyanate and a chain extender as described above. In the present invention, the polyol component is preferably used when the polyol component is 65% by weight or more of the whole. Yes, particularly preferred is 68% by weight or more. When the content of the polyol component is small, the elongation and elongation recovery of the obtained nonwoven fabric are low. These polyurethane elastomers may contain a plasticizer pigment, a stabilizer and the like. [0009] The nonwoven fabric is formed by laminating and forming polyurethane elastic filaments without bonding over substantially the entire length of the yarn. If the monofilaments are joined in a bundled state without being opened, the flexibility of the nonwoven fabric is significantly impaired. The diameter of the filament is usually 30 μm or less on average, preferably 2 μm on average.
5 microns or less, particularly preferred is 20 microns or less. The diameter of the monofilament may vary, but at most 50 μm or less is desirable. As the diameter of the monofilament increases, the nonwoven fabric becomes coarse and rigid. The cross-sectional shape of the polyurethane elastic fiber constituting the non-woven fabric can take various shapes such as a circular shape, an irregular shape, and a hollow shape. preferable. [0011] The nonwoven fabric is formed by laminating polyurethane elastic filaments, and the points of contact of the fibers constituting the laminate are joined by heat fusion of the fibers themselves. Such a bonding state can be achieved by fusing the polyurethane elastic fibers to each other by heat. A method using a solvent or a method using another adhesive is not preferable because the air permeability and flexibility of the nonwoven fabric are reduced. However, it is acceptable to use an adhesive together as long as these properties are not impaired. One of the important features of the nonwoven fabric is that the nonwoven fabric has extremely high breaking strength and elongation and excellent elastic performance. This is because the performance of the polyurethane elastic fiber constituting the nonwoven fabric is directly reflected, and is obtained with a nonwoven fabric made of a conventionally known inelastic polymer or a nonwoven fabric made of a polymer having poor elasticity such as a polyester ether elastic material. Performance that cannot be achieved. Nonwoven fabrics usually have a breaking elongation of 3
It is at least 00%, preferably at least 500%. Although the breaking strength varies depending on the thickness of the nonwoven fabric, it is usually 0.4 kg / cm per 100 g / m ² and preferably 1.0 kg / c.
m. The recovery rate at 100% elongation is usually 85% or more, preferably 90% or more. The strength, elongation, and elongation recovery of the nonwoven fabric vary depending on the adhesive strength of the contact points between the fibers constituting the nonwoven fabric. This indicates that the bonding is sufficiently performed. The greatest feature of the above nonwoven fabric is that it is extremely flexible. The rigidity of the nonwoven fabric is (JISL-1
096, 45 ° cantilever method), which increases as the basis weight of the nonwoven fabric increases, but the nonwoven fabric obtained by the present invention has a basis weight of x (g / m ² ) and a bristles of y (mm). Usually, y <0.2 × + 20, and preferably y <0.2 × + 10. This feature is obtained in combination with the physical properties of the polyurethane elastic body, the structure of the nonwoven fabric and the small diameter of the constituent fibers as described above, and is achieved by a conventionally known web of polyurethane elastic fibers by a wet method or a dry method. It couldn't be done. Next, the steps of the method of the present invention will be described. The thermoplastic polyurethane elastic body is melted and discharged from a spinneret using, for example, a spinning apparatus described in Japanese Patent Publication No. 41-7883, and the filament is thinned by a heated gas flow spouting from both sides of a nozzle. Let it be. The thinned filaments are separated from the gas stream on an auxiliary device such as a moving conveyor net without being substantially bundled, and are laminated on the net.
The laminated filaments are laminated by their own heat, and the contact points of the filaments are joined by the filaments themselves. Before or after cooling and solidifying after the lamination on the collecting device, they may be joined by heating and pressing using a roller or the like. In order to strengthen the bonding of the contact points between the filaments, the distance from the spinneret to the position where the filaments are stacked on the collecting device should not be too long, and is at most 1 m, preferably 50 cm or less. A gas flow guide passage may be provided between the base and the collecting device, but may be omitted. The nonwoven fabric of the present invention uses the above-mentioned thermoplastic polyurethane elastic body as a polymer. More preferably, a polyisocyanate compound is added to a molten polyurethane elastic body, kneaded, and then discharged from a spinning nozzle. Good. The nonwoven fabric made of polyurethane elastic fiber is
Utilizing its excellent elasticity, flexibility and air permeability, it is used alone for various applications, but it can be made into various products by combining it with other materials. Examples of such a material include non-elastic polymers such as synthetic fibers such as polyester, nylon, polyolefin, and acrylic, and woven or knitted fabrics, nets, nonwoven fabrics, and webs made of natural fibers such as cellulose and wool. Further, a film of polyurethane or the like, a foamed sheet, or the like is also used. As such products and uses, as materials for various kinds of clothing such as sportswear and foundation which require elasticity, there are interlining, batting, reinforcing agents, stretch tapes, bands and the like. Further, since it has a fitting property to various shapes, a cushion property, and a moldability, it is useful as a packing, a cushion material, a filler, and a molding material. Applications utilizing the friction coefficient and abrasion resistance peculiar to the polyurethane elastic body include various types of non-slip materials such as shoe lining materials. The present invention will be described below with reference to examples. The measurement of various physical property values was performed by the following methods. Breaking strength and elongation: A sample having a width of 2 cm
According to S 1096, the grip interval is 5 cm, and the pulling speed is 10
Elongate at cm / min, and measure the strength and elongation per 1 cm width at break. 100% elongation recovery rate: A sample having a width of 2 cm is stretched by 100% at a gripping interval of 5 cm and a pulling speed of 10 cm / min, and immediately recovered to the original length at the same speed. From the recorded load-elongation curve, the residual elongation percentage 1 (%) is obtained, and the 100% elongation recovery rate is calculated by the following equation. [Formula 1] Bending resistance: According to the 45 ° cantilever method of JISL-1096. Air permeability: A Frazier type tester of JISL-1096 was used. Example 1 5548 parts of dehydrated polytetramethylene glycol having a hydroxyl value of 102 (all parts below mean parts by weight) and 1.
499 parts of 4-bis (β-hydroxyethoxy) benzene was charged into a kneader equipped with a jacket, dissolved sufficiently with stirring, and then maintained at a temperature of 85 ° C.
-1953 parts of diphenylmethane diisocyanate were added and reacted. When the stirring is continued, a powdery polyurethane is obtained in about 30 minutes. The polyurethane is formed into pellets by an extruder, and a concentration of 1 g / measured in dimethylformamide at 25 ° C.
A 100 cc polyurethane elastomer having a relative viscosity of 2.50 was obtained. Using the polyurethane elastomer pellets thus obtained as a raw material, a melt blow spinning apparatus having a slit for injecting a heated gas at both sides of a nozzle having a diameter of 0.8 mm arranged in a line was used to melt at a temperature of 245 ° C. The polymer was discharged at a rate of 0.5 g per minute per nozzle, and air heated to 200 ° C. was jetted from the slit at a pressure of 3.5 kg / cm ² to be fine. The thinned filaments are collected on a 30-mesh wire mesh conveyor placed 25 cm below the nozzle,
A take-off non-woven fabric was obtained with a roller. In this nonwoven fabric, monofilaments of polyurethane elastic fibers were spread and laminated, and the entanglement points between the filaments were joined to each other by fusion. The physical properties of this nonwoven fabric were as follows. Weight 180 g / m ² Tensile strength 1.0 kg / cm Elongation at break 685% 100% elongation recovery 92% Bending degree 54 mm Filament diameter 20 microns Air permeability 173 cm ³ / cm ³ / sec Since this nonwoven fabric is flexible and has high stretchability and air permeability, it is effective for sports clothing and foundation use in combination with stretchable fabric foil. Example 2 In the same manner as in Example 1, a polyurethane elastic nonwoven fabric having a filament diameter of 10 to 25 microns and an average of 15 microns was produced by increasing the injection pressure of heated air. The physical properties of this nonwoven fabric were as follows. Weight 180 g / m ² Tensile strength 0.9 kg / cm Elongation at break 690% 100% Elongation recovery 92% Bending degree 45 mm Breathability 166 cm ³ / cm ³ / sec Example 3 By the method of Example 1, various amounts of the polyurethane elastic fiber nonwoven fabric were manufactured by changing the discharge amount and the take-off speed of the polymer. All filament diameters were between 20 and 30 microns. Table 1 shows the physical property values of each nonwoven fabric. [Table 1] The rigidity increases as the basis weight increases,
Each of the values satisfied the expression (1). Immediately after collection on the conveyor net, pressing with a hot roll at 130 ° C. further reduced the value of the softness. For comparison, a commercially available polyurethane fiber (40 denier, 4 filaments) was cut into 8 mm, and a web having a basis weight of 120 g / m ² was prepared by a paper machine and heated and pressed at 150 ° C. for 5 minutes. Was. Further, the weight of the filament was reduced to 50 microns by reducing the jet pressure of the heated air.
The sheet having a g / m ² web heated and pressed at 150 ° C. had a stiffness of 65.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an explanatory diagram showing a relationship between a basis weight and a degree of softness.

Claims (1)

(57) [Claims] Reaction of polyol, chain extender and organic diisocyanate
After melt-spinning the obtained thermoplastic polyurethane elastic body, a high-temperature gas stream is jetted, and substantially continuous filaments obtained by thinning are laminated in a sheet shape. the filament itself of self
Heat by brought melt bonded with and then characterized and this <br/> hot pressing method for producing a polyurethane elastic fiber nonwoven fabric is basis weight 100 g / m ² per breaking strength 0.4 kg / cm or more. 2. Reaction of polyol, chain extender and organic diisocyanate
After melt-spinning the obtained thermoplastic polyurethane elastic body, a high-temperature gas stream is injected, and the substantially opened filament obtained by the thinning is placed on a collection device at a distance of at most 50 cm from the spinneret. Laminating and bonding the laminated filaments by their own heat at the contact points of the laminated filaments. The breaking strength per unit weight of 100 g / m ² is 0.4 kg / cm or more. A method for producing a polyurethane elastic fiber nonwoven fabric.