JP4058011B2 - Non-woven - Google Patents

Description

  The present invention relates to a non-woven fabric having a relatively small strength difference between a machine direction (MD direction) and a direction intersecting the machine direction (CD direction) and having a large number of undulations on the surface.

In the nonwoven fabric wiper disclosed in JP-A-8-60509 (Patent Document 1), a laminate of a hydrophilic fiber web and a hydrophobic fiber web is continuously supplied in one direction. It is treated with a high-pressure jet water stream sprayed from a nozzle, and the constituent fibers of both webs are rearranged and mechanically entangled with each other to form a nonwoven fabric. Thereafter, the nonwoven fabric is heat treated to crimp the composite fibers contained in the web, thereby forming a large number of irregularities on the nonwoven fabric surface. The unevenness thus obtained acts to scrape off dirt adhering to an object when the nonwoven fabric is used as a wiper.
JP-A-8-60509

  In the nonwoven fabric obtained by injecting a high-pressure columnar water stream onto a fiber web that is continuously supplied in one direction, most of the fibers directly under the columnar water stream are eliminated laterally, and the fibers extend as valleys along the web supply direction. It will be understood by those skilled in the art that the portions having a low surface density and the portions having a high fiber surface density in which the excluded fibers are accumulated and extend in a crest along the web supply direction are alternately formed in the width direction of the web. well known. It is also well known that the MD direction of such a nonwoven fabric has a high tensile strength and is difficult to stretch, and the CD direction has a low tensile strength and is easy to stretch. In other words, the strength and easiness of elongation of this nonwoven fabric vary greatly depending on the direction. When this nonwoven fabric is used as a wiper, attention must be paid to its directionality so that it cannot be easily broken.

  This invention makes it a subject to provide the nonwoven fabric which can be used without minding the directionality about tensile strength or easiness of elongation.

  The present invention for solving the above-mentioned problem is premised on having a first surface and a second surface which are parallel to each other, and the fibers are formed by mechanically entanglement between the two surfaces in one direction. Highly and lowly parallel fiber surface density portions extending in either a continuous or intermittent manner are arranged alternately in a direction intersecting the one direction, and the first surface has a high surface density. It is a nonwoven fabric in which undulations are formed such that the part becomes a mountain and the part having the low surface density becomes a valley.

Under such a premise, the present invention is characterized by being manufactured by a manufacturing method including the following steps a to c, and straddling a portion having a high surface density and a portion having a low surface density adjacent to each other in a direction crossing the one direction. The bridge portion having a higher density than that of the low surface density portion extends.
a. A step of continuously supplying the fiber web in one direction.
b. Supplying the fiber web directly below a high-pressure columnar water stream ejected from a plurality of nozzles arranged in a line in the width direction of the web in a range in which a supply speed reduction rate defined below is 16 to 35%.
Supply speed deceleration rate (%) =
(Supply speed before columnar water flow)-(Take-up speed after columnar water flow)
───────────────────────────── × 100
(Take-up speed after columnar water flow)
c. A step of drawing the web treated with the columnar water flow along the one direction within the range of the supply speed reduction rate.

  In one embodiment of the present invention, the low surface density portion has a width in the direction intersecting the one direction in the range of 0.05 to 0.5 mm.

  In another embodiment, in the bridge portion, a part of the fiber extends in a direction crossing the one direction.

  In another embodiment, the fibers are either short fibers or continuous fibers.

In another embodiment, the columnar water flow is produced by being jetted from a direction inclined 4 to 15 degrees forward of the web supply direction with respect to the vertical direction of the web to be supplied.

  Since the nonwoven fabric according to the present invention has a high and low fiber surface density portion extending in one direction parallel to each other and a bridge portion extending across these portions, the one direction and the one direction The difference in tensile strength and elongation in the intersecting direction is reduced, and the nonwoven fabric becomes homogeneous.

  The details of the nonwoven fabric and its manufacturing method according to the present invention will be described with reference to the accompanying drawings.

1, 2 and 3 are a perspective view of the nonwoven fabric 1 and sectional views taken along lines II-II and III-III. The nonwoven fabric 1 is formed by mechanically interlacing the fibers 2 with each other. The upper surface 3 rich in undulations is less undulating than the upper surface 3, is relatively smooth , and is parallel to the upper surface 3. And a lower surface 4. The non-woven fabric 1 is alternately arranged in the double-headed arrow X direction, and has a high fiber surface density portion (high-density portion) 6 extending substantially parallel to the double-headed arrow Y direction orthogonal thereto, and a low fiber surface density portion ( Low density part) 7. In addition, the nonwoven fabric 1 has a bridge portion 8 that extends in the direction of the arrow X across at least one of these portions 6 and 7 and has a fiber surface density higher than that of the low-density portion 7. The fiber surface density (hereinafter, also simply referred to as surface density) used here is the number of fibers existing in a unit area when the nonwoven fabric 1 is viewed in plan from the upper surface 3 to the lower surface 4. Means.

As the fiber 2, thermoplastic synthetic fiber, natural fiber such as pulp, chemical fiber such as rayon, or a mixture of these fibers is used at a basis weight of 20 to 200 g / m ² . The synthetic fiber preferably has a fineness of 0.1 to 3d, and is used after being hydrophilized if necessary.

  In the high density portion 6, the fibers 2 located in the vicinity of the upper surface 3 are generally oriented in the Y direction. More fibers 2 are accumulated in the high density portion 6 than in the low density portion 7, the thickness is thick, and the top portion 9 is located above the low density portion 7. The width of the high density portion 6 in the direction of the arrow X is preferably about 0.05 to 5 mm, and the thickness of the thickest portion is preferably in the range of about 0.2 to 1 mm.

  In the low density region 7, there are a case where the fibers 2 are generally oriented in the Y direction and a case where the fibers 2 are not oriented in a specific direction. The fiber 2 is not present in the low density part 7 as much as the high density part 6, and the thickness is the thinnest at the bottom 11. The width of the low density portion 7 in the direction of arrow X is preferably about 0.02 to 0.5 mm, and the thickness of the bottom 11 is preferably in the range of about 0.02 to 0.5 mm. The high-density part 6 and the low-density part 7 have undulations repeated in the direction of the arrow X so that one is a mountain and the other is a valley. The low density portion 7 is a portion having a lower tensile strength in both the X and Y directions than the high density portion 6 and easily extending in both the X and Y directions.

  The bridge portion 8 extends in the arrow X direction so as to intersect the adjacent high density portion 6 and the low density portion 7 substantially at right angles or obliquely. The top portion of the bridge portion 8 is substantially the same height as the top portion 9 of the high-density portion 6 or is higher than the top portion 9. However, the height of the bridge portion 8 in the vicinity of the end portion 13 may be lower than the top portion 9 of the high-density portion 6. The width and length of the bridge portion 8 are not specified, but to give an example, the width is about 0.5 to 1 mm, the length is about 5 to 100 mm, and the arrow Y direction is about 1 to 3 mm. And the pitch when appearing repeatedly. A part of the fibers 2 of the bridge portion 8 may be oriented in the X direction. The fiber 2 extends between the bridge portion 8 and the high-density portion 6 and between the bridge portion 8 and the low-density portion 7, and the fiber 2 causes the bridge portion 8 and these portions 6, 6 to extend. 7 is integrated. The fiber surface density of the bridge portion 8 may be the same as or higher than that of the low density portion 7 and may be higher than that of the high density portion 6. When the entire nonwoven fabric 1 is viewed, the bridge portion 8 thus formed may be recognized as a large number of wrinkles formed on the upper surface 3 or the upper and lower surfaces 3 and 4 of the nonwoven fabric 1.

  If the non-woven fabric 1 is not as shown in FIG. 1 and has a high-density portion 6 and a low-density portion 7 but no bridge portion 8 is formed, the non-woven fabric When pulled in the direction of the arrow X, it is particularly easy to stretch at the low density portion 7 and torn easily at the portion 7. Further, when pulled in the arrow Y direction, the high-density portion 6 does not stretch or tear as easily as when pulled in the X direction. Thus, in the nonwoven fabric 1 of this invention in which the bridge portion 8 is formed on a nonwoven fabric having a difference in strength and elongation between the X direction and the Y direction, that is, a nonwoven fabric having a large directionality, the low density is obtained due to the presence of the bridge portion 8. The elongation of the part 7 is suppressed, the tensile strength is improved, the difference in strength and elongation in the X direction and the Y direction is reduced, and the nonwoven fabric 1 becomes a homogeneous one with a small directionality.

  The nonwoven fabric 1 obtained in this way is used as, for example, a wiper for wiping dirt on the wall surface, and when the wall surface is rubbed by moving it in the direction of the arrow Y, the dirt on the wall surface can be scraped off by the bridge portion 8. In addition, when the difference in thickness between the high-density part 6 and the low-density part 7 is large and a large step occurs between these parts 6 and 7, if the nonwoven fabric 1 is moved in the direction of the arrow X and the wall surface is rubbed, Dirt can be scraped off even at the level difference. In addition, since the nonwoven fabric 1 is homogeneous and there is no significant difference in strength or elongation between the X direction and the Y direction, the nonwoven fabric 1 can be broken regardless of whether it is moved in the X direction or the Y direction. The wall surface can be rubbed without doing.

  In the case where the constituent fibers 2 of the nonwoven fabric 1 are continuous fibers, when the nonwoven fabric 1 is used as a wiper, the fibers do not fall off, and there are no cases where fiber waste adheres to the wall surface from which dirt has been wiped off. Moreover, when the constituent fiber 2 is a short fiber, the production speed is faster than when continuous fibers are used, and accordingly, the cost of the nonwoven fabric 1 can be reduced.

FIG. 4 is a drawing showing a manufacturing process of the nonwoven fabric 1. From the left side of the figure, a raw material web 100 supplied from a combing web machine or the like is supplied at a speed v ₁ and placed on a drum-like support 102 rotating in the right direction, and a high-pressure columnar water stream 103 is jetted from above. The columnar water stream 103 is ejected from a large number of micro-hole nozzles 104 arranged in a line in the width direction of the web 101. The fibers constituting the web 100 are rearranged by the water stream and at the same time mechanically connected to each other. The entangled nonwoven fabric 101 is obtained. The nonwoven fabric 101 is pulled rightward at a speed v ₂ and used as the nonwoven fabric 1 of FIG. The width direction (CD direction) of the web 100 is the X direction of the nonwoven fabric 1 in FIG. 1, and the traveling direction (MD direction) of the web 100 is the Y direction of the nonwoven fabric 1.

In this step, when the supply speed v ₁ is larger than the take-up speed v ₂ and is based on v ₂ ,
Supply speed deceleration rate R (%) = (v ₁ −v ₂ ) / v ₂ × 100
Both velocities v ₁ and v ₂ are set so that is 16 to 35%. Further, the nozzle 104 is positioned such that the direction of jetting of the columnar water flow onto the web 100 placed on the drum 102, that is, the slope A from the perpendicular H to the web 100 in FIG. Is set to

  As a result, a large number of wrinkles 106 extending in the width direction of the web 100 are formed immediately before the columnar water flow 103 on the web 100, and at the same time, the wrinkles 106 are fixed to the web 101 in an almost intact shape by the columnar water flow 103. The fixed wrinkle 106 becomes the bridge portion 8 of the nonwoven fabric 1. As is well known to those skilled in the art, in the web 100 traveling in one direction, most of the constituent fibers of the web 100 are eliminated laterally at the portion where the columnar water stream 103 is directly jetted, and the low density of the nonwoven fabric 1 Site 7 is formed. The excluded fibers are accumulated between the columnar water stream and the columnar water stream to form a high-density portion 6. In the illustrated process, a suction mechanism is provided inside the drum 102 (not shown), and the post-injection columnar water flow is quickly sucked.

  According to the present invention, a large number of wrinkles 106 can be formed on the web 100 by injecting the columnar water stream 103 obliquely forward with respect to the web 100. It can be oriented in the width direction. The bridge portion 8 obtained from the wrinkle 106 in this manner brings many fibers to the low density portion 7 and at least a part of the fibers is oriented in the width direction of the web 100, thereby causing the nonwoven fabric 1 in the X direction. The tensile strength is improved and the nonwoven fabric 1 is hardly stretched in the X direction.

Example 1
A web having a basis weight of about 30 g / m ² made of a polypropylene continuous fiber having a fineness of 0.5 d was put into the step of FIG. 4 to obtain a wrinkled nonwoven fabric as shown in FIG. The nonwoven fabric has a basis weight of 1 g and a tensile strength per 1 cm of width.
Strength in MD direction S _MD = 36.7 (g / cm) / (g / m ² )
Strength in CD direction S _CD = 27.3 (g / cm) / (g / m ² )
S _CD / S _MD = 0.74
Met.
(Production conditions)
Columnar water jet angle (A) 7.2 °
Supply speed deceleration rate (R) 33%

(Example 2)
The tensile strength of the nonwoven fabric obtained under the same conditions as in Example 1 except that the columnar water jet angle (A) was 10.1 ° was as follows.

S _MD = 33.0 (g / cm) / (g / m ² )
S _CD = 25.8 (g / cm) / (g / m ² )
S _CD / S _MD = 0.78

(Comparative Example 1)
The web used in Example 1 was put into the process of FIG. 4 and the tensile strength of the wrinkle-free nonwoven fabric obtained under the following production conditions was as follows.

S _MD = 53.3 (g / cm) / (g / m ² )
S _CD = 25.8 (g / cm) / (g / m ² )
S _CD / S _MD = 0.48
(Production conditions)
Columnar water jet angle (A) 0 °
Supply speed deceleration rate (R) 0%

(Comparative Example 2)
The tensile strength of the non-wrinkled nonwoven fabric obtained under the same conditions as in Comparative Example 1 was as follows except that the columnar water jet angle was inclined by 3.4 ° in the direction opposite to the web flow direction.

S _MD = 47.8 (g / cm) / (g / m ² )
S _CD = 24.2 (g / cm) / (g / m ² )
S _CD / S _MD = 0.51

From the values of S _CD / _SM D in Examples 1 and 2 and Comparative Examples 1 and 2, it can be seen that the difference in strength between the MD direction and the CD direction of the nonwoven fabric according to the present invention is smaller than that in the comparative example.

The top view of a nonwoven fabric. II-II sectional view taken on the line of FIG. III-III sectional view taken on the line of FIG. The manufacturing process figure of a nonwoven fabric.

Explanation of symbols

1 Nonwoven fabric 2 Fiber 3 First surface (upper surface)
4 Second surface (lower surface)
6 High density part 7 Low density part 8 Bridge part 100 Web 103 Columnar water flow 104 Nozzle

Claims (5)

Parallel fibers having a first surface and a second surface that are parallel to each other and formed by mechanically interlacing the fibers between the two surfaces and extending in one direction in either a continuous or intermittent manner Sites with high surface density and regions with low surface density are alternately arranged in a direction intersecting the one direction, and the first surface has a mountain with the high surface density and a valley with the low surface density. A nonwoven fabric with undulations formed thereon ,
It is manufactured by a manufacturing method including the following steps a to c, and crosses the adjacent high-density area and low-density area in a direction crossing the one direction, and has a higher density than the low-area density area. The nonwoven fabric characterized in that the bridge portion extends :
a. Continuously supplying a fiber web in one direction;
b. Supplying the fiber web directly below a high-pressure columnar water stream ejected from a number of nozzles arranged in a line in the width direction of the web in a range in which the rate of deceleration of supply speed defined below is 16 to 35%;
Supply speed deceleration rate (%) =
(Supply speed before columnar water flow)-(Take-up speed after columnar water flow)
───────────────────────────── × 100
(Take-up speed after columnar water flow)
c. A step of drawing the web treated with the columnar water flow along the one direction within the range of the supply speed reduction rate . The nonwoven fabric according to claim 1, wherein the portion having a low surface density has a width in a direction intersecting with the one direction of 0.05 to 0.5 mm. The nonwoven fabric according to claim 1 or 2, wherein a part of the fiber extends in a direction intersecting the one direction at the bridge portion. The nonwoven fabric according to any one of claims 1 to 3, wherein the fibers are either short fibers or continuous fibers. The columnar water flow is manufactured by being jetted from a direction inclined by 4 to 15 degrees forward of the web supply direction with respect to a vertical direction of the web to be supplied . Non-woven fabric.

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