Spunbonded nonwoven fabric

Abstract

A spunbonded nonwoven fabric of the present invention is characterized by being composed of a polyolefin fiber, wherein the average pore diameter of the nonwoven fabric surface is 0.1-25 μm, the maximum pore diameter is 50 μm or less, and the water pressure resistance per unit basis weight is 7 mmH₂O/(g/m²) or more.

Description

CROSS REFERENCE TO RELATED APPLICATIONS[0001]This is the U.S. National Phase application of PCT / JP2018 / 040408, filed Oct. 30, 2018, which claims priority to Japanese Patent Application No. 2017-211607, filed Nov. 1, 2017 and Japanese Patent Application No. 2018-141052, filed Jul. 27, 2018, the disclosures of each of these applications being incorporated herein by reference in their entireties for all purposes.FIELD OF THE INVENTION[0002]The present invention relates to a spun-bonded nonwoven fabric composed of polyolefin fibers, which is excellent in waterproofness and softness, and is excellent in moldability as building material applications.BACKGROUND OF THE INVENTION[0003]In recent years, nonwoven fabrics have been used in various applications and are expected to grow in the future. The nonwoven fabrics are employed in a wide range of applications such as industrial materials, civil engineering materials, building materials, living materials, agricultural materials, sanitary mat...

AI Technical Summary

Benefits of technology

[0029]The polyolefin-based resin in the present invention has a melting point of preferably 80° C. to 200° C., more preferably 100° C. to 180° C., and even more preferably 120° C. to 180° C. By setting the melting point to preferably 80° C. or higher, more preferably 100° C. or higher, and even more preferably 120° C. or higher, heat resistance that can withstand practical use is easily attained. By setting the melting point to preferably 200° C. or lower, more preferably 180° C. or lower, the filaments discharged from a spinneret is easily cooled, fusion of fibers are prevented and stable spinning is easily performed.

[0030]The polyolefin fibers constituting the spun-bonded nonwoven fabric in the present invention preferably have an average single fiber diameter of 6.5 to 11.9 μm. By setting the average single fiber diameter to preferably 6.5 μm or more, more preferably 7.5 μm or more, and even more preferably 8.4 μm or more, a decrease in spinnability can be prevented and a high-quality nonwoven fabric can be stably produced. Meanwhile, by setting the average single fiber diameter to preferably 11.9 μm or less, more preferably 11.2 μm or less, and even more preferably 10.6 μm or less, a spun-bonded nonwoven fabric having high uniformity in the surface of the nonwoven fabric can be made, and hence a spun-bonded nonwoven fabric with small pore diameter in the surface thereof and with excellent water resistance that can withstand practical use can be obtained.

[0031]The polyolefin fibers constituting the spun-bonded nonwoven fabric in the present invention preferably has CV value of a single fiber diameter of 0.1% to 7.0%. By setting the CV value of the single fiber diameter to preferably 0.1% or more, more preferably 1.0% or more, and even more preferably 2.0% or more, complication of production equipment and extreme reduction in productivity can be prevented. Meanwhile, by setting the CV value of the single fiber diameter to preferably 7.0% or less, more preferably 6.0% or less, and even more preferably 5.0% or less, occurrence of a rough feeling on the surface is prevented, and a laminated nonwoven fabric having high uniformity can be obtained. Back pressure of a spinneret, uniformity of yarn cooling conditions and stretching conditions mainly affect the CV value of the single fiber diameter, and the CV value can be controlled by appropriately adjusting them.

[0032]The polyolefin fiber constituting the spun-bonded nonwoven fabric in the present invention preferably has an MFR of 155 to 850 g / 10 min. By setting the MFR thereof to preferably 155 to 850 g / 10 min, more preferably 155 to 600 g / 10 min, even more preferably 155 to 400 g / 10 min, the filaments being discharged can readily follow deformations, even when the filaments are drawn at a high spinning speed to increase the productivity. Stable spinning is hence possible. In addition, since stable drawing at a high spinning speed is possible, orientation and crystallization of the fibers can be promoted to impart high mechanical strength to the polyolefin fibers.

[0033]In a preferred embodiment of the spun-bonded nonwoven fabric of the present invention, from the standpoint of improving slipperiness between the fibers, slipperiness as texture, and softness, the polyolefin-based fibers, which are constituent fibers, composed of polyolefin resins contain a fatty acid amide compound having 23 or more and 50 or less carbon atoms.

[0034]It is known that the number of carbon atoms of a fatty acid amide compound incorporated into the polyolefin fibers affects the change in a moving speed of the fatty acid amide compound to the fiber surface. By setting a fatty acid amide compound to preferably have 23 or more carbon atoms, more preferably 30 or more carbon atoms, excessive exposure of the fatty acid amide compound on the fiber surface is inhibited, excellent spinnability and working stability are attained, and high production efficiency is hence maintained. Further, when the filaments are collected as a spun-bonded nonwoven fabric web, moderate slipperiness can be imparted to the fibers, and the uniformity of the nonwoven fabric surface can be attained and the pore diameter of the nonwoven fabric surface can be made smaller. Meanwhile, by setting a fatty acid amide compound to preferably have 50 or less carbon atoms, more preferably 42 or less carbon atoms, this fatty acid amide compound readily migrates to the fiber surface, making it possible to impart slipperiness between the spun-bonded nonwoven fabric fibers or slipperiness and softness of the nonwoven fabric surface.

Problems solved by technology

However, since the house wrapping material in the related art is a laminate of a nonwoven fabric and a film, there is a problem that the sheet is hard and has poor moldability.

The hardness and the poor moldability of the sheet are due to the film, and reducing a proportion of the film to be bonded is effective, but the reduction of the film proportion is restricted in view of waterproofness.