Nonwoven material and method of manufacture therefor

Abstract

A flexible, recyclable and sewable nonwoven textile formed from first fibers having a high temperature polyester core and a low temperature thermoplastic sheath, and second thermoplastic fibers formed from a high temperature polyester. The nonwoven textile is formed by blending the first thermoplastic staple with the second thermoplastic staple, carding the blend into a web, cross lapping the fibers of the web into a mat, needling the mat, heating the mat to a temperature above the melt temperature of the low temperature thermoplastic thereby forming unions between the fibers.

Description

BACKGROUND

[0001] The present invention generally relates to nonwoven textiles, and in particular, to recyclable nonwoven textiles that are sewable.

[0002] Nonwoven textiles are typically produced by making a mat of fibers, and securing those fibers together to form a textile. The fibers of the mat can be secured together through mechanical connecting, adhesive bonding, or thermal fusing.

[0003] Nonwoven textiles are used in various applications such as backing material for fabrics in automotive applications or as a stand alone textile. To be used as a backing material for fabrics, the material will have properties that enable the ease of sewing the material. Additionally, there has been a recent interest in using only materials that are recyclable for applications such as automotive use. Therefore, it is one objective of the current invention to produce a nonwoven textile that is recyclable and has desirable sewability characteristics.

BRIEF DESCRIPTION OF THE DRAWINGS

[0004] These and other features, aspects, and advantages of the present invention will become better understood with regard to the following description, appended claims, and accompanying drawings where:

[0005] FIG. 1 shows an enlarged cross-section of a nonwoven material illustrating one embodiment of the present invention;

[0006] FIG. 2 shows an enlarged cross-section of a first fiber from the nonwoven material in FIG. 1;

[0007] FIG. 3 shows a block diagram of a process for forming the nonwoven in FIG. 1; and

[0008] FIG. 4 shows a test sample of an example material that has been folded open.

DETAILED DESCRIPTION

[0009] Referring now to the figures, and in particular to FIG. 1, there is shown an enlarged cross-sectional view of a nonwoven textile 10 illustrating an embodiment of the present invention. The nonwoven textile 10 is highly flexible, which facilitates its ability to be used as a backing material for fabrics. The nonwoven textile 10 is also a recyclable and sewable material. The nonwoven textile also has superior seam strength. These properties permit the use of the nonwoven textile 10 as a backing material for fabrics such as fabrics used in automotive applications.

[0010] What is meant by “flexible” is that the material will tend to bend or fold over under its own weight when held horizontal.

[0011] What is meant by “recyclable” is that the item is made up of materials of the same or similar chemical nature which can be converted into the basic raw material status for use in forming new items.

[0012] What is meant by “sewability” or “sewable” is that the material is easily penetrated by a sewing needle and stitched with a thread.

[0013] What is meant by seam strength, is the ability of a material to retain its strength at a seam. The tensile strength of a material contributes to seam strength. One method of testing seam strength is to measure the gap between two sections of the material that have been sewn together, after having subjected the sewn together material to a specific number of flex cycles. In another method of testing seam strength, the ultimate tensile strength of two sections of material sewn together, after having subjected the sewn together material to a specific number of flex cycles.

[0014] The nonwoven textile 10 generally comprises a plurality of first fibers 20 intermixed with a plurality of second fibers 30. As shown in FIG. 2, the first fibers 20 generally include a core material 21 and a sheath material 22. The core material 21 and the sheath material 22 of the first fibers 20 are preferably a thermoplastic, and more preferably, a thermoplastic that is recyclable such as polyester. Additionally, the core material 21 of the first fibers 20 has a higher melting point than the sheath material 22. The second fibers 30 are also preferably a thermoplastic material, and more preferably, a recyclable thermoplastic material such as polyester. The material of the second fibers 30 has a higher melting point than the sheath material 22 of the first fibers 20.

[0015] The first fibers 20 and the second fibers 30 are intertwined within the nonwoven textile 10 through a process of needle punching. Additionally, at various crossing points of various first fibers 20 and the crossing of first fibers 20 with second fibers 30, a bond point 11 is created between the crossing fibers 20, 30, due to the melt fusing of the sheath material 22 in the first fibers 20.

[0016] The nonwoven textile 10 is preferably 4-15 ounces per square yard, and includes a ratio of from about five to about twenty percent (5-20%) by weight of the first fibers 20 to the total weight of the combination of the first fibers 20 and the second fibers 30. The sheath material 22 of the first fibers 20 is preferably a low melt temperature thermoplastic, such as a low melt temperature polyester, that is between about 5 to about 15% of the total weight of the first fiber 20. The core material 21 of the first fiber 20 is preferably a high melt temperature thermoplastic, such as a high melt temperature polyester, that is between about 85 to about 95% of the total weight of the first fiber 20. The first fiber 20 is also preferably between about 4-6 denier. The second fiber 30 is preferably a high melt temperature polyester having a denier between about 3-12. The first fibers 20 and the second fibers 30 are mechanically locked with needle punches of between about 1100 and about 1800 punches per square inch.

[0017] Referring now to FIG. 3, there is shown a block diagram illustrating one embodiment of a method for forming the nonwoven textile 10 in FIG. 1. In the process illustrated in FIG. 3, the first fibers 20 are supplied from a first fiber supply 111, and second fibers 30 are supplied from a second fiber supply 112. The first fibers 20 and the second fibers 30 are blended in a blending step 120 with a ratio of from about five to about twenty percent (5-20%) by weight of the first fibers 20 to the total weight of the combination of first fibers 20 and second fibers 30. The blended fibers from step 120 are carded into a web form in the carding step 130. The web from the carding step 130 is cross lapped in cross lapping step 140 to insure crossing of the various fibers into a mat.

[0018] After the cross lapping step 140, the mat is needled in the needling step 150. The needling step 150 creates between about 1100 and about 1800 punches per square inch to entangle and mechanically lock together the fiber of the mat. After the mat has been cross lapped in the cross lapping step 140, and needled in the needling step 150, the mat is subjected to heat in a heating step 160. The heating step 160 brings the fibers in the mat to a temperature greater than the lower melt temperature of the sheath material 22 in the first fibers 20, thereby softening the sheath material. During the heating step 160, adjacent second fibers 30 embed into the softened sheath material 22 of the first fibers 20, and sheath material 22 of adjacent first fibers 20 intermix, thereby forming bond points 11. After the mat is heated to a temperature to form bond points 11 between fibers, the mat is cooled in a cooling step 170 below the melting point of the sheath material to produce the nonwoven textile 10.

[0019] In one example, a first fiber having a core of high melt polyester and a sheath of low melt polyester is combined with second fibers of a high melt polyester. The high melt polyester core of the first fiber is about 90% of the weight of the first fiber. The first fiber was about a 4 denier fiber. The second fiber was about a 6 denier fiber. The first fibers and the second fibers were blended with a ratio of about five percent (5%) to about twenty percent (20%) by weight of the first fibers 10 to the total weight of the combined first fibers 10 and the second fibers 30. After the fibers were blended into a mat, carded, and cross lapped, the mat was needled punched at the rate of about 1,650 punches per inch. After needling, the mat was subjected to a temperature of between about 275° and about 305° for a period of about 180 seconds. The high temperature was sufficient to cause the sheath material of the first fiber to flow around adjoining fibers and form random point bonds in the material. The resulting material became a recyclable nonwoven textile of polyester that is flexible and easier to sew than current technology.

[0020] Various samples of the example material were measured for tensile strength by measuring the elongation when about a 120 N (27 lb) force was applied across about a 76.2 mm (inches) wide sample. Samples tested with the force applied in the machine direction of the material experienced between about 6.3% and about a 8.3% elongation during the application of the force, and between about a 2.1% and about a 3.1% permanent elongation. Samples tested with the force applied along the cross direction of the material experienced between about 3.4% and about 9.4% elongation during the application of the force, and between about a 1.0% and about a 3.1% permanent elongation.

[0021] To test the seam strength of the material from the example above, sections of the example material above were sewn together into various test sample using 58N (13 lb.) test nylon thread, Material Standard MS-JZ3-2, with a No. 22 size sewing needle at about 0.24 stitches/mm (6 stitches/in.). Two sections 210 and 220 of the example material were configured into the test samples 200 according to FIG. 4. The two sections 210/220 of example material are sewn together at the seam 230 with the facing surfaces F1 and F2 contacting each other, and then folded open to the configuration in FIG. 4. Each section 210/220 includes tabs 211 and 221 with grasping points 212 and 222.

[0022] The seam of various test samples were subjected to 10,000 cycles of flex for measuring the seam strength. Each cycle of flex is accomplished by grasping the grasping points of each tab 210/220, moving one of the two the grasping points 34.9 mm (1.375 inches) opposite of the other grasping point laterally along the seam 230 with 35.59 N (8 lbs) force at 42 cycles per minute. Each cycle produces a total of 139.6 mm (5.5 inches) movement of the grasping points 210/220 along the seam 230 (34.9 mm from center in each direction and back).

[0023] Various samples of the example material were tested for the gap between the two sections at the seam after being subjected to the flex cycles. After the flex cycles, the gap between the two sections of material at the seams was about 1.0 mm (0.039 inches) or less for seams across the machine direction of the material, and the gap was about 1.5 mm (0.059 inches) or less for seams across the cross direction of the material.

[0024] Various samples of the example material were also tested for the strength of the material at the seam after being subjected to the flex cycles. After the cycles of flex, an increasing load was applied to the grasping points 210/220 across the seam 230 of the test sample according to FIG. 1, until failure occurred. No failure of the of the example material adjacent to the seam was notice when a load of about 720 N (164 lb) or greater was applied to a sample having the seam across the machine direction of the example material, or when a load of about 1030 (231.5 lb) or greater was applied to a sample having the seam across the cross direction of the example material.

[0025] Although the present invention has been described in considerable detail with reference to certain preferred versions thereof, other versions are possible. Therefore, the spirit and scope of the appended claims should not be limited to the description of the preferred versions contained herein.

Claims

1. A nonwoven material comprising a plurality of fibers intermingled and fused together, said fibers being formed of a recyclable material, and wherein said nonwoven material is sewable.

2. The nonwoven according to claim 1, wherein said nonwoven material is flexible.

3. The nonwoven according to claim 1, wherein said recyclable material comprises a thermoplastic material.

4. The nonwoven according to claim 3, wherein said fibers are polyester.

5. The nonwoven according to claim 1, wherein said fibers are entangled through needlepunching.

6. The nonwoven according to claim 1, wherein the fibers of said nonwoven material comprise a first fiber having an exterior portion with a first melt temperature, and a second fiber having a second melt temperature, wherein said first melt temperature is lower than said second melt temperature.

7. The nonwoven according to claim 6, wherein said fibers are entangled through needlepunching.

8. The nonwoven according to claim 6, wherein the exterior portion of said first fiber comprises a sheath having the first melt temperature and said first fiber further comprises a core having a core melt temperature, and wherein said core melt temperature is higher than said first melt temperature.

9. The nonwoven according to claim 8, wherein said fibers are entangled through needlepunching.

10. A method for forming a nonwoven material including the steps of:

(a) blending a first thermoplastic staple fiber having an outer area with a first melting point with a second thermoplastic staple fiber having a higher second melting point;

(b) carding the blend of the first thermoplastic staple fiber and the second thermoplastic staple fiber into a web;

(c) crosslapping the fibers of the carded web into a mat;

(d) needle punching the cross lapped mat to entangle the fibers of the mat;

(e) heating the mat to a temperature above the first melting point of the first thermoplastic staple fiber until at least a portion of the first thermoplastic staple fibers form a union with other first thermoplastic staple fibers and second thermoplastic staple fibers; and,

(f) cooling the mat below the first melting temperature of the first thermoplastic staple fibers.

11. The method according to claim 10, wherein the first thermoplastic staple fiber has a core and a sheath, the sheath having the first melting point and the core having a melting point higher than the first melting point.

12. The method according to claim 10, wherein said step of needling includes the step of needling between 1100-1800 punches per inch.