Load restraint strip with stitchbond fabric base layer
10654399 ยท 2020-05-19
Inventors
Cpc classification
B32B3/266
PERFORMING OPERATIONS; TRANSPORTING
B32B5/10
PERFORMING OPERATIONS; TRANSPORTING
B32B2307/54
PERFORMING OPERATIONS; TRANSPORTING
D04H1/52
TEXTILES; PAPER
B32B27/12
PERFORMING OPERATIONS; TRANSPORTING
B32B2553/00
PERFORMING OPERATIONS; TRANSPORTING
B32B5/26
PERFORMING OPERATIONS; TRANSPORTING
D04H3/115
TEXTILES; PAPER
B32B7/12
PERFORMING OPERATIONS; TRANSPORTING
International classification
Abstract
A cargo load restraint strip may have a base layer that comprises a stitchbond fabric. A separate reinforcement layer may comprise reinforcing strands or other type of material to increase tensile strength. An adhesive layer may be configured for attachment to a container wall and may include a release paper liner that may be peeled away prior to such attachment.
Claims
1. A load restraint strip comprising: a base layer, wherein the base layer comprises a stitchbond fabric extending throughout the base layer; a reinforcement layer fixed relative to the base layer, wherein a material of the reinforcement layer is different from the stitchbond fabric; and an adhesive layer fixed relative to the reinforcement layer, wherein one of the base layer and the reinforcement layer is located between the adhesive layer and the other of the base layer and the reinforcement layer.
2. The load restraint strip of claim 1, wherein the load restraint strip has a length from a first end to a second end, a width that is less than the length, and an attachment region extending from the first end to a location between the first and second ends, and wherein the adhesive layer is confined to the attachment region.
3. The load restraint strip of claim 2, wherein the length is at least 9 feet and the width is between 10 inches and 20 inches.
4. The load restraint strip of claim 2, wherein the length is at least 9 feet and the width is between 24 inches and 50 inches.
5. The load restraint strip of claim 2, wherein the length is at least 9 feet and the width is at least 36 inches.
6. The load restraint strip of claim 1, wherein the load restraint strip has a length from a first end to a second end and a width that is less than the length, and wherein a tensile strength of the reinforcement layer along a direction of the length is greater than a tensile strength of the base layer along the direction of the length.
7. The load restraint strip of claim 1, further comprising a liner sheet adhered to the adhesive layer, wherein the liner sheet is nondestructively removable to expose the adhesive layer.
8. The load restraint strip of claim 1, wherein the stitchbond fabric comprises a nonwoven mat with stitches formed by stitching yarns that penetrate the nonwoven mat.
9. The load restraint strip of claim 8, wherein the stitchbond fabric is a Maliwatt stitchbond fabric.
10. The load restraint strip of claim 8, wherein the nonwoven mat comprises carded 1.5 denier per fiber polyester fibers, and wherein the mat has a basis weight of between 65 grams per square meter and 300 grams per square meter.
11. The load restraint strip of claim 1, wherein the stitchbond fabric comprises at least one agent selected from a group that includes an adhesive primer agent, a static reduction agent, and a sizing agent.
12. The load restraint strip of claim 1, wherein the load restraint strip has a length from a first end to a second end and a width that is less than the length, wherein the material of the reinforcement layer comprises a plurality of substantially parallel strands extending in a direction of the length, wherein the strands are distributed over substantially all of a width of the load restraint strip and have a distribution density of between 5 and 25 strands per inch in a direction across the width.
13. A method comprising: affixing a first attachment region of a first load restraint strip to a first interior wall of a cargo container, wherein the first load restraint strip comprises a stitchbond fabric first base layer, a first reinforcement layer fixed to the first base layer, and an exposed first adhesive layer in the first attachment region; affixing a second attachment region of a second load restraint strip to a second interior wall of the cargo container, wherein the second load restraint strip comprises a stitchbond fabric second base layer, a second reinforcement layer fixed to the second base layer, and an exposed second adhesive layer in the second attachment region; after the affixing of the first attachment region to the first interior wall and the affixing of the second attachment region to the second interior wall, wrapping tails of the first and second load restraint strips around cargo located in the cargo container; and securing the tails to each other.
14. The method of claim 13, wherein each of the first load restraint strip and the second load restraint strip has a length from a first end to a second end of at least 9 feet and a width that is at least 36 inches.
15. The method of claim 14, wherein the stitchbond fabric first base layer and the stitchbond fabric second base layer each comprises a nonwoven mat with stitches formed by stitching yarns that penetrate the nonwoven mat.
16. The method of claim 13, wherein the stitchbond fabric first base layer and the stitchbond fabric second base layer each comprises a nonwoven mat with stitches formed by stitching yarns that penetrate the nonwoven mat.
17. The method of claim 16, wherein each of the mats comprises carded 1.5 denier per fiber polyester fibers, and wherein each of the mats has a basis weight of between 65 grams per square meter and 300 grams per square meter.
18. The method of claim 13, wherein each of the stitchbond fabric first base layer and the stitchbond fabric second base layer comprises at least one agent selected from a group that includes an adhesive primer agent, a static reduction agent, and a sizing agent.
19. The method of claim 13, wherein the first load restraint strip has a first length from a first end of the first load restraint strip to a second end of the first load restraint strip and a first width that is less than the first length, wherein a tensile strength of the first reinforcement layer along a direction of the first length is greater than a tensile strength of the first base layer along the direction of the first length, wherein the second load restraint strip has a second length from a first end of the second load restraint strip to a second end of the second load restraint strip and a second width that is less than the second length, and wherein a tensile strength of the second reinforcement layer along a direction of the second length is greater than a tensile strength of the second base layer along the direction of the second length.
20. The method of claim 19, wherein the first reinforcement layer comprises a plurality of substantially parallel first strands extending in a direction of the first length, wherein the first strands are distributed over substantially all of the first width and have a distribution density of between 5 and 25 strands per inch in a direction across the first width, wherein the second reinforcement layer comprises a plurality of substantially parallel second strands extending in a direction of the second length, and wherein the second strands are distributed over substantially all of the second width and have a distribution density of between 5 and 25 strands per inch in a direction across the second width.
21. The method of claim 13, wherein each of the first load restraint strip and the second load restraint strip has a length from a first end to a second end of at least 9 feet and a width that is between 10 inches and 20 inches.
Description
BRIEF DESCRIPTION OF THE DRAWINGS
(1) Some embodiments are illustrated by way of example, and not by way of limitation, in the figures of the accompanying drawings and in which like reference numerals refer to similar elements.
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DETAILED DESCRIPTION
(16) As described in more detail herein, novel load restraint strips according to at least some embodiments include a backing layer that is formed from a stitchbond fabric. Load restraint strips incorporating a stitchbond fabric backing can offer advantages over previously-known load restraint strips. For example, a stitchbond fabric backing can be used to stiffen the load restraint strip. In some embodiments, and as compared to previously-known load restraint strips, this can provide a load restraint strip which is more likely to remain in a desired orientation during installation. For example, during installation of load restraint strips according to some embodiments, an installer may grip tails of two load restraint strips in a single location in preparation for use of a tightening tool. While gripping those two tails in that single location, unsecured portions of those tails are less likely to move out of position before the installer can place a tightening tool onto the tails.
(17) Although stitchbond fabric backing can make a load restraint strip stiffer, such material does not appreciably affect the tensile strength or tensile elastic modulus of the strip relative to strips using other types of backing material that might also increase strip stiffness. For example, certain types of cross-weave materials can be used as a backing or reinforcement layer in a load restraint strip. Such cross-weave materials may tend to stiffen a load restraint strip. Yet they also tend to significantly increase the tensile strength a load restraint strip. Surprisingly, this is not always desirable.
(18) In particular, and although it is somewhat counterintuitive, a load restraint strip can become less effective if tensile strength is increased too much. This is believed to be the result of a loss in tensile elasticity that normally accompanies a tensile strength increase. If a strip is insufficiently elastic, the adhesive attaching the strip to a container wall may pop off in response to a high G load. By using stitchbond fabric as a backing material and different type of material to provide tensile reinforcement, the tensile strength and tensile elasticity of a load restraint strip and the stiffness of the load restraint strip can be separately controlled.
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(20) Wave-shaped notations are added to
(21) Also visible in
(22) As indicated in
(23) In some embodiments, multiple strips 100 may be joined together and wound on a roll. Lines of perforations may separate ends 104 and 103 of adjacent strips strip 100 on that roll. Strips 100 can be removed from the roll by tearing or cutting along the lines of perforations.
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(25) In the embodiment of strip 100, adhesive layer 106 extends throughout attachment region 132. A first end 107 of adhesive layer 106 and of attachment region 132 is aligned with first end 103 of strip 100 and of working portion 131. A second end 108 of adhesive layer 106 and of attachment region 132 is located between first end 103 and second end 104 of strip 100 and of working portion 131. As indicated in
(26) As seen in
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(28) Base layer 114 is formed by band 115 of stitchbond fabric. As is known in the textile arts, stitchbond fabric is created by mechanically bonding nonwoven material with stitches. Stitchbond fabric is also known as stitch bond, stitch-bond, stitchbonded, stitch bonded, and stitch-bonded fabric. Although stitchbond fabric is created through a process that may be called stitchbonding (or stitch bonding, etc.), a stitchbond fabric has a particular type of fabric structure that is distinct from fabric structures formed by other processes. In particular, a stitchbond fabric is a hybrid material in which a nonwoven fiber substrate material is reinforced and structurally defined by knitting stitches that penetrate that substrate. In some types of stitchbond fabric, the substrate may be a mat or web of nonwoven fibers, and the stitching may be separate yarns that penetrate that substrate, with those yarns knitted to create a pattern of nonwoven regions separated by stitching yarns. In other types of stitchbond fabric, the stitching may be created by fibers taken from the nonwoven mat.
(29) There are numerous types of stitchbond fabrics. A Maliwatt stitchbond fabric comprises a mat of nonwoven batting that is knitted together by a stitching yarn that penetrates the batting. A Malivlies stitchbond fabric is similar to Maliwatt, but a separate stitching yarn is not used. Instead, fibers taken from the batting are used to form stitches in the batting. Other types of stitchbond fabrics include, without limitation, Kunit, Multiknit, Malipol, Voltex, and Malimo fabrics.
(30) As represented schematically in
(31) TABLE-US-00001 TABLE 1 Exemplary Stitchbond Fabric Properties Property Example Value basis weight (in ounces/yard.sup.2) 4.6 thickness (mils) 25 grab tensile strength, 82 machine direction (lbs) grab tensile strength, 80 cross direction (lbs) elongation, 16 machine direction (%) elongation, 8 cross direction (%) modulus (lbs) 64
(32) The basis weight in Table 1 represents measurements according to the method described by ASTM standard D3776. The thickness in Table 1 represents measurements according to the method described by ASTM standard D1777. The grab tensile strengths in Table 1 represents measurements according to the method described by ASTM standard D5034. In some embodiments, a stitchbond fabric used as the material of band 115 may have values for one or more of the properties in Table 1 that are approximately as shown in Table 1, e.g., within a range of +/5% of a value shown in Table 1. For example, a stitchbond fabric used as the material of band 115 in some embodiments may have a basis weight of between 4.4 ounces/yard.sup.2 and 4.8 ounces/yard.sup.2, and/or a thickness of between 24 mils and 26 mils, and/or a machine direction grab tensile strength of between 78 lbs and 86 lbs, and/or a cross direction grab tensile strength of between 76 lbs and 84 lbs, and/or a machine direction elongation of between 15% and 17%, and/or a cross direction elongation of between 7.6% and 8.4%, and/or a modulus of between 61 lbs and 67 lbs.
(33) In some embodiments, a stitchbond fabric used as the material of band 115 may comprise one or more agents that have been applied to the fabric by immersion or other technique. In some embodiments, a stitchbond fabric may comprise an adhesive primer agent. In some embodiments, a stitchbond fabric may comprise a static reduction agent. In some embodiments, a stitchbond fabric may comprise a sizing agent such as starch. In some embodiments, a stitchbond fabric may include a combination of some or all of these agents.
(34) Reinforcement layer 110 is fixed relative to base layer 114. In particular, reinforcement strands 111 are bonded to an exterior side of band 115 by a laminating adhesive 118. In the embodiment of strip 100, strands 111 are parallel to one another and to the length L.sub.W direction of working portion 131, and there are no strands 111 oriented in other directions. In some embodiments, each of strands 111 comprises one or more polymer fibers and has a denier (i.e., a linear mass density in grams per 9000 meters) of between about 1400 and about 1650. In some embodiments, strands 111 may have a denier between about 1450 and about 1600. In certain embodiments, the denier of strands 111 may be between about 1479 and about 1547, with target denier of about 1513. In some embodiments, reinforcement layer 110 includes between about 100 reinforcing strands 111 and about 320 reinforcing strands 111 in a load restraint strip having a width W.sub.W of 16 inches, resulting in a strand distribution density (in a direction across width W.sub.W and perpendicular to length L.sub.W) of between 6.25 and 20 strands per inch. In some embodiments, a load restraint strip (regardless of width W.sub.W) may have a strand distribution density (in a direction across width W.sub.W and perpendicular to length L.sub.W) of between 5 and 25 strands per inch. Exemplary materials for strands 111 include polyester. Table 2 shows exemplary properties for polyester strands 111 in some embodiments.
(35) TABLE-US-00002 TABLE 2 Exemplary Polyester Strand Properties Target Min. Max. Property Value Value Value liner density (denier, 1513 1479 1547 i.e. g/9000 m) break load (pounds) 26.6 24.6 28.7 elongation at break (%) 10.3 8.8 11.8 elongation at 10 lb. load (%) 3.4 2.9 3.9 shrinkage, free (%) 8.4 4.8 12.0
(36) The ranges in Table 2 are solely for purposes of example. Embodiments include load restraint strips in which reinforcing strands have one or more properties significantly outside a range indicated in Table 2. Embodiments also include load restraint strips in which a reinforcement layer comprises reinforcement strands formed from glass, polypropylene, carbon, or some other material. In at least some embodiments, reinforcing layer 110 has a greater tensile strength, in a direction parallel to length L.sub.W, than backing layer 114.
(37) In at least some embodiments, laminating adhesive 118 is a transparent ethylene vinyl acetate water based copolymer adhesive having a viscosity between about 2900 centipoise (cps) and about 3200 cps. Embodiments include load restraint strips in which a laminating adhesive has a viscosity significantly outside this range and/or comprises a different type of adhesive. As indicated above, adhesive 118 is used to bond reinforcing fibers 111 to an exterior side of band 115. In some other embodiments, reinforcing fibers may also or alternatively be bonded to an interior side of a base layer material.
(38) Adhesive layer 106 is fixed relative to reinforcement layer 110 and relative to base layer 114. Unlike reinforcement layer 110 and base layer 114, however, and as seen in
(39) In at least some embodiments, adhesive sublayers 121 and 119 contain the same type of adhesive. In at least some such embodiments, adhesive sublayers 121 and 119 contain an acrylic adhesive having a shear strength of between about 50 psi and about 100 psi. Embodiments include load restraint strips in which an adhesive layer adhesive has properties significantly outside this range and/or comprises a different type of adhesive. In some embodiments adhesive layer 106 has a thickness of approximately 3 mils (with 1 mil=0.001 inch), although embodiments include load restraint strips with adhesive layers having a substantially different thickness.
(40) Substrate sublayer 120 may comprise a film of polyethylene terephthalate (PET) or other polymer and may have a thickness of between about 0.5 mils and about 1.0 mils. When a substrate sublayer is present, it may make little or no contribution to the load restraining strength of strip 100 and may simply serve as a carrier for adhesive sublayers 121 and 119. In particular, adhesive layer 106 may initially take the form of a double-sided adhesive tape having substrate sublayer 120 sandwiched by adhesive sublayers 119 and 121. Liner 101 may be attached to one side of that tape. A portion of that double sided tape can be cut from a larger roll and applied to a portion of a partially-completed strip 100 during the manufacturing process. A substrate sublayer may not be present in some embodiments. In some such embodiments lacking an adhesive layer substrate, a layer of acrylic adhesive substantially similar to sublayer 121 can be applied to a partially-completed strip 100 using transfer tape.
(41) In other embodiments, sublayers 121 and 119 may comprise different types of adhesives. As explained in more detail below, adhesive sublayer 121 is adhered to a shipping container wall when strip 100 is installed. Many applications require that the adhesive bond between sublayer 121 and a container wall be nonpermanent. When a container reaches its destination and strip 100 is removed, it is desirable that little or no adhesive residue remain on the container wall. For this and other reasons, it is often desirable for sublayer 121 to be a high shear strength pressure-sensitive acrylic adhesive that can accommodate a large temperature gradient. Because adhesive sublayer 119 does not contact a container wall, however, adhesive residue is not a concern for this layer. Accordingly, sublayer 119 can comprise other types of adhesives having different properties than the adhesive used for sublayer 121. For example, the adhesive of sublayer 119 could be selected to have higher shear and peel strengths than the adhesive of sublayer 121 so as to ensure that substrate sublayer 120 does not separate from strip 100 when strip 100 is removed from a container wall. In some such embodiments, the sublayer 119 adhesive could be a rubber based type of adhesive or could be an acrylic adhesive with a different formulation than the adhesive of sublayer 121.
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(45) Strip 100(1) has been attached to an inner surface of left side wall 203 of container 200. In particular, a release paper liner similar to liner 100 (
(46) Also visible in
(47) This simplified handling also facilitates use of restraint strips having larger widths W.sub.W. In general, and for two load restraint strips that are otherwise of identical construction, a wider load restraint strip will have a greater cargo restraining capacity than a narrower load restraint strip. Using wider strips can potentially reduce the total number of strips needed, thereby reducing material and labor costs associated with securing cargo for shipment. However, wider strips can be more cumbersome to handle than narrower strips if conventional backing materials are used. When trying to affix a tightening tool, for example, it may be difficult for a single worker to keep tails of conventionally-backed strips aligned. If ungripped portions of those tails are easily moved, and as further discussed below, it may be more difficult to attach a tightening tool. Stiffer tails are more likely to remain in place while a worker attaches a tightening tool.
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(49) Although
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(51) When a situation such as is shown in
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(55) Although the stitchbond fabric backing of load restraint strips according to various embodiments increases the stiffness of those strips, those strips remain pliable and can be tightened with conventional tightening tools using hand force of a single installer. In some embodiments, the stiffness provided by a stitchbond fabric backing may cause a load restraint strip to retain a curl when the strip is unrolled from a roll of strips. If desired, this curl can be eliminated using hand force or by using a tension bar on the back side of the strip during unrolling. In some embodiments, however, the residual curl in an unrolled strip may advantageously used.
(56) When conventional load restraint strips are attached to a container wall, the tail must often be temporarily taped to the wall. Otherwise, the tail may be snagged and/or damaged during cargo loading. As shown in
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(58) In step 302, a second attachment region of a second exterior face of a second load restraint strip is attached to a second interior wall of a cargo container. The second load restraint strip comprises a stitchbond fabric second base layer, a second reinforcement layer fixed to the second base layer, and an exposed second adhesive layer in the second attachment region. One example of step 302 is attachment of strip 100(2) to the interior side of wall 202, as also discussed above in connection with
(59) In step 303, and after the affixing of the first attachment region to the first interior wall and the affixing of the second attachment region to the second interior wall, tails of the first and second load restraint strips are wrapped around cargo located in the cargo container. An example of step 303 is the wrapping of tails 133(1) and 133(2) around cargo units 210, as discussed above in connection with
(60) In step 304, ends of the wrapped tails of the load restraint strips are secured to each other. An example of step 304 is the affixation of connecting patch 211, as discussed above in connection with
(61) The foregoing description of embodiments has been presented for purposes of illustration and description. The foregoing description is not intended to be exhaustive or to limit embodiments to the precise form explicitly described or mentioned herein. Modifications and variations are possible in light of the above teachings or may be acquired from practice of various embodiments. The embodiments discussed herein were chosen and described in order to explain the principles and the nature of various embodiments and their practical application to enable one skilled in the art to make and use these and other embodiments with various modifications as are suited to the particular use contemplated. Any and all permutations of features from above-described embodiments are within the scope of the invention.