Toray Industries, Inc.

Takuji Kobayashi

Yuji Iyama

Yohei Nakano

Yoshikazu Yakake

Shingo Hayashi

Sachio Inaba

Yuka Nishiguchi

Daiki Shimada

Youhei Nakano

The present invention provides an electret fiber sheet having superior recovery of airflow volume by heat treatment and having high air permeability. The electret fiber sheet of the present invention is a nonwoven fabric formed from long fibers that are formed from a thermoplastic resin and have an average single fiber diameter of 0.1 to 8.0 &#x3bc;m, wherein a bulk density of the nonwoven fabric is 0.05 to 0.30 g/cmand the long fibers contain a crystal nucleating agent at 0.005 to 1.0% by mass.

Electret fiber sheet

The present invention provides a spun-bonded nonwoven fabric which is configured from polyolefin fibers that have excellent spinnability even if the single fiber diameter thereof is small, and which exhibits high flexibility and high uniformity. The present invention relates to a spun-bonded nonwoven fabric which is configured from fibers that are formed from a polyolefin resin and have a single fiber diameter of 6.5-14.5 &#x3bc;m, and which has a melt flow rate of 155-850 g/10 minutes and a CV value of the thickness of 13% or less.

Spun-bonded nonwoven fabric

A fiber sheet is densely charged with electric charge and provides an electret fiber sheet that has excellent dust collecting performance. The electret fiber sheet is an electret fiber sheet in which averages of a* values and b* values satisfy all requirements of the following (a) to (c): (a) 10&#x2264;average of (a* values)&#x2264;40; (b) &#x2212;25&#x2264;average of (b* values)&#x2264;0; and (c) &#x2212;5&#x2264;average of [(a* values)+(b* values)]&#x2264;40; wherein a* and b* are values measured by a spectrophotometer when a red positive charge toner and a blue negative charge toner are attached.

A melt-blown nonwoven fabric includes a fiber containing a thermoplastic resin, wherein apparent density is 0.1 to 0.4 g/cmand KES surface roughness of at least one surface of the fabric sheet is up to 1.2 &#x3bc;m; and a method of producing the fabric includes conveying a web of the nonwoven fabric by sandwiching the web between two belt conveyers each including a belt having a smooth surface, providing a heat treatment zone where a surface of one or both of the belt conveyers has been heated to a temperature not lower than cold crystallization temperature of the thermoplastic resin and not higher than the temperature &#x2212;3&#xb0; C. lower than melting temperature of the thermoplastic resin in at least a part of a course between the belts, and heating the nonwoven fabric web in the heat treatment zone by contacting both surfaces of the nonwoven fabric web with the belt.

Melt-blown nonwoven fabric and method of manufacturing same

Problem: The present invention allows a fiber sheet to be densely charged with electric charge and provides an electret fiber sheet that has excellent dust-collecting characteristics. Solution: The electret fiber sheet according to the present invention is an electret fiber sheet in which the relationship between a* and b* measured by a spectrophotometer when a red positive charge toner and a blue negative charge toner are attached to the sheet satisfies the expression: [12&#x2264;{&#x2212;(b*)&#x2212;(a*)}&#x2264;50].

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Otsu, Japan

Takuji Kobayashi