DK145470B - PROCEDURE FOR MANUFACTURING A DESIGNED BIOXIAL ORIENTED NON-WOVEN SUBSTANCE - Google Patents

Description

fw) (19) DENMARK \ RR ^

| J | (12) PUBLICATION MANUAL OR 1U5470B

DIRECTORATE OF THE PATENT AND TRADEMARKET SYSTEM

(21) Application No. 5697/76 (51) intCI. * D 04 H 1/74 (22) Filing Day 17 · Dec. 1976 (24) Running day 17-Dec. 1976 (41) Aim. available Jun 20 1977 (44) Presented Nov. 22; 1982 (86) International Application No. - (86) International Filing Day (85) Continuation Day "(62) Master Application No." *

(30) Priority 19 · Dec. 1975, 642667, US

(71) Applicant THE KENDALL COMPANY, Walpole, US.

(72) Inventor Preston Fairfax Marshall, US.

(74) Associate Engineer Lehmann & Ree.

(54) Process for producing a patterned, biaxially oriented, nonwoven fabric. ·

The present invention relates to a method of producing a patterned biaxially oriented nonwoven fabric in which an aqueous suspension of a mixture of long fibers of 1 length of at least 12.7 mm and short fibers of length less than 12.7 mm is caused to flow from an overpressure container and onto a moving Fourdrinier mesh through a mask.

The object of the present invention is to produce - a patterned, biaxially oriented, nonwoven fabric having strips d "of high fiber density, wherein the fibers are predominantly oriented parallel to the stripping direction, alternating with stripes of low fiber density. "" density, wherein the fibers are predominantly oriented perpendicular to the stripping direction, thereby obtaining a fabric having substantially the same tensile strength in both the machine direction (longitudinal direction) and in the transverse direction while providing the fabric with great softness and drape. -ability.

Swiss Patent No. 537,481 discloses a method for making patterned fibrous webs by discharging an aqueous suspension onto a screen whose screen openings are blocked in accordance with the desired pattern. However, this patent does not provide instructions on how to make a striped, nonwoven fabric in which the fibers have a precise biaxial orientation.

Further, from the specification of British Patent No. 1,063,672, a method of making a patterned, nonwoven fabric is known by flowing on a papermaking machine an aqueous suspension of fibers onto a moving mesh through a pattern-forming mesh with a coarser web masks. However, even by this method, nonwoven fabric is produced in which there is a precise biaxial orientation of the fibers.

U.S. Patent No. 3,350,260 discloses a method by which a suspension of long and short fibers flows out onto a moving mesh having areas covered in a predetermined pattern, but also not in this patent specification provides instructions on how to make a fabric in which the fibers appear precisely oriented biaxially in two mutually perpendicular directions.

Finally, from U.S. Pat.

No. 3,775,244 discloses a process for making a web-shaped paper fabric. This substance can e.g. consist of strips of high fiber density alternating with stripes of low fiber density. It is further stated and illustrated by way of example that the paper web can be made of long fibers with a length of 15 mm and short pulp fibers. However, there is no mention in the patent that the fibers are oriented perpendicular to each other from stripe to stripe, nor are there any instructions in the manufacturing procedure which will lead to this result.

The object of the present invention is achieved by a method of the kind mentioned in the preamble, characterized in that the masking is constituted by liquid impervious, finger-like resistance areas arranged equidistantly over or on the web and extending parallel to the direction of movement of the web, wherein the width and distance are between the resistance regions is such that most of the long fibers and large fibers are deposited on the web between the resistance regions to form strips of high fiber density, wherein the fiber jaw is oriented in a direction parallel to the longitudinal direction of the resistance regions, while the rest of the long fibers are deposited across the resistance regions and oriented in a direction perpendicular: on the resistance regions to form strips of low fiber density. =

In the process of the invention, one stock is made of mixed long and short fibers, the long fibers having a length of at least 1.27 cm and the short fibers having a length less than 1.27 cm; the stock is kept in a stirred state and caused to flow into a dustbin in which it is stabilized; the stabilized stock is caused to flow down onto the running Fourdrinier net which has liquid impervious, finger-like resistance ranges as indicated above.

In one embodiment of the method according to the invention, the distance between the edges of the strip bars is less than the average length of a long fiber.

In another embodiment of the method according to the invention, the distance between the edges of the stripping rods is less than half the average length of a long fiber.

If the nonwoven fabric is made with a substantial thickness of 2, corresponding to a surface weight of more than approx. 53.8 g / m, there will be a tendency for random orientation of these fibers in the tops of the striped web. This is due to the fact that as the layer thickness of fibers increases, the fibers deposited at the top of the web will be less affected by the forces trying to pull the fibers in place between resistance regions, and these fibers will therefore be less likely to become arranged in a striped arrangement. Nevertheless, a striped fabric with such a layer of randomly oriented fibers on one side of the fabric can also be made by the method of the invention and will also offer the advantages characteristic of fabric made by this method.

The invention will now be described in more detail with reference to the drawing, in which:

FIG. 1 is a plan view of a nonwoven fabric made by the method of the invention; and FIG. 2 is a flow diagram illustrating the method.

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FIG. 1 shows a single layer woven fabric 10 with alternating high fiber density stripes 11 and low fiber density stripes 12. As can be seen from the drawing, the majority of the fibers in the stripes 11 are oriented in a direction which substantially follows the direction of movement of a running Fourdrinier mesh on which the fabric is made (the machine direction), i.e. that these fibers are directed substantially parallel to the length of the fabric. However, the majority of the fibers in the stripes 12 are oriented in a direction which substantially follows the width of the fabric 10 (transverse orientation), i.e. that these fibers are directed substantially perpendicular to the fibers of the stripes 11 and form bridges between the stripes. These alternating, streaked regions of alternate orientation are formed simultaneously as described below.

A nonwoven fabric, such as that shown in FIG. 1, is produced by a papermaking technique in which a stock of a mixture of long and short fibers is prepared and stored in a trough at a particular consistency while being stirred to prevent the solids settle and separate. From the supply, the mixture flows into an inlet distributor system which spreads the current to the entire machine width and discharges it into a dust collection box in which the flow is stabilized. The stabilized mixture then flows onto a running Fourdrinier wire mesh which moves around a perforated gauss to which suction is applied to drain the water and causes the fibers to deposit on the web.

The net carries liquid-impervious resistance areas in the form of continuous, parallel stripes extending longitudinally of the net. Alternatively, parallel stripping bars extending longitudinally of the net may be placed over the net in the flow path of the stock on the net. Such stripping rods are similar to those used in the apparatus described in the description of DK Pat. 4178/75, using which an unwoven fabric is formed by depositing an airborne stream of fibers on a running net. As the stock flows out of the web, a major portion of both the long and short fibers is drawn to the areas that are outside the resistance areas or the strip bars.

This is especially the case for the short fibers, since they are not subjected to forces arising from more than one area outside the liquid-impervious regions, and therefore do not attempt to bridge a liquid-impervious region. Due to the movement of the web, they are more attracted to the parts of the web which lie between the liquid impervious areas and are oriented parallel to the machine direction of the web of the fibers formed on the web.

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Provided that the stripping rods or resistance regions are spaced sufficiently close together - the space between them should generally not be less than the average length, and preferably less than half the average length of a long fiber, those fibers which do not bridge between the stripping rods or the resistor regions, are inserted into a high fiber density strip located between the striping bars or resistor regions. In a high fiber density strip, the majority of the fibers are oriented in the longitudinal direction of the tissue.

As previously mentioned, the long fibers have a length of minchSt 1.27 cm, while the short fibers, scan can be paper fibers, cotton liners or short thermoplastic fibers or combinations thereof, have a length less than 1.27 cm. If short thermoplastic fibers are used either alone or in conjunction with other short fibers, they will be drawn into the high fiber density strips and, under heat action, they will bond the long bridging fibers at the ends incorporated into such strips. but will leave the bridging fibers substantially free of bonding between the high fiber density stripes, thus increasing the drape and softness in these areas and throughout the fabric.

The gap between the high fiber density strips containing long and short fibers should be at least equal to the width of such a strip, but not so large that the long fibers are unable to bridge them. Although some short fibers will appear in low fiber density strips mixed with the long bridging fibers, a majority of the short fibers will be deposited in the high fiber density strips.

In all substances except the lightest, the upper part of the fabric, i.e. the part of the fabric furthest away from the Fourdrinier mesh is covered by a small amount of long and short fibers which are placed randomly or generally across the tissue. As the fibers in the supply stream settle on the web and the resistance regions or form a thicker layer and pass beyond the stripping rods, the fibers are generally less controlled by the divergent action of the water located between the liquid-permeable and liquid-impervious regions and deposited on the upper part of the woven in a somewhat random way. In these circumstances, the fabric can best be described as containing high and low fiber density stripes with an integrated cover layer of somewhat randomly oriented long and short fibers. However, a majority of the fibers are nonetheless located ψί. streaked way and with an orientation parallel to the longitudinal direction of the tissue.

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If the stripping rods or resistance areas are moved closer together in such a way that the center distance is 1.9 cm, a much more pronounced ribbed structure is formed. By "ribbed structure" is meant that the high fiber density strips contain so many fibers that they are almost semi-circular in shape, while the low fiber density strips remain more or less flat.

The tissue is further conveyed by the web to a zone where the fibers are bonded in the orientation described above, e.g. by depositing an adhesive on the tissue or, in the case where some of the fibers are thermoplastic fibers, by passage under a heat exchanger. Finally, the bonded, nonwoven web is removed from the web by a suitable pickup device.

The nonwoven fabrics made according to the invention have a wide range of applications, e.g. as disposable curtains or curtains, as decorative, narrow ribbons and / or flower ribbons, as sweat straps, as adhesive dressings and as disposable tablecloths.

The invention will be further illustrated by the following example:

Example In the example, a laboratory-size paper-making machine was used. The machine was equipped with a 30.5 cm wide and 15 cm deep outlet box and suction was provided under the net. Liquid impermeable streaks oriented in the machine direction were provided in the form of 1.6 mm thick bronze strips placed on top of the net. The individual strips had a width of 3.2 mm and their centers were spaced 4.8 mm apart.

At the outlet box, at a rate of 222.2 kg per kg. mine. added a slurry.

The slurry was composed as follows:

Water 99.90%

Long fiber (1½ denier 3.8 cm viscose rayon) 0.02%

Connecting fiber (3 denier 6.4 rm cut)

Vinyon fibers 0.02%

Paper Fiber (Paper Flock Fiber) 0.06% 100.00%

The substance was passed from the outlet box to a suction box which reduced the water content to 132 g / m.

The fabric was then dried on a drum roll and further heated on bonding drum rolls to 152 ° C to melt 7AA5A70

Vinyon fibers.

Examination of the fabric showed that the transverse weight of the narrow 1.6 mm wide rods, which covered 1/3 of the track, was approx. 108 g / m2 or contributed approx. 36 g / m to the total flat weight of the fabric The weight of the fabric in the 3.2 mm wide strips, which made up 2/3 of the 2 2 web, was approx. 18 g / m or contributed approx. 12 g / m to the total surface weight of the fabric. Thus, the total surface weight of the fabric was 12. +, 36 = 48 g / m2.

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