Method for Producing Patterned Nonwovens and Laminated Nonwovens

Abstract

Methods are provided for producing patterned nonwoven materials and patterned laminated multilayer materials which include one or more layers of nonwoven. A nonwoven with heat-activatable binder fibers or binder materials is heated, subjected to patterned pressure. This softens or melts the binder and allows movement of the fibers in the nonwoven according to the pattern pressure. Then, the nonwoven is cooled so that the binder solidifies to lock a durable three-dimensional pattern into the structure. With a multilayer layup, for example, including a substrate layer, an adhesive layer, and a nonwoven layer, the layup is heated to melt the adhesive and soften binder in the nonwoven, then subjected to pattern pressure such as by being pressed with patterned plates, belts, or rollers, and cooled to bond the layers together, and to bond the fibers in the nonwoven according to the pattern pressure so as to fix the pattern. The processes may be carried out in batch mode or continuously using a flatbed laminating machine with heating and cooling zones. Engraved rollers, which may be heated or cooled depending on process conditions, can also be employed. The resulting materials exhibit stable three-dimensional patterns, typically 1-25 mm deep, suitable for functional and aesthetic applications.

Claims

1. A method for producing a patterned nonwoven material, comprising: heating a nonwoven material comprising staple fibers together with heat-activatable binder fibers or binder material in the nonwoven structure, wherein the heating softens or melts the heat-activatable binder fibers or binder material allowing the staple fibers to move relative each other in the heated nonwoven material, applying patterned pressure to the heated nonwoven material in one or more areas to form one or more patterns extending into a thickness of the nonwoven material; and cooling the nonwoven material so that the binder fibers or binder material solidifies to form the one or more patterns into the one or more areas of a cooled nonwoven material, wherein the cooled nonwoven material has varying thicknesses across its one or more areas which correspond to the applied patterned pressure.

2. The method of claim 1, wherein the patterned pressure is applied by one or more engraved rollers, patterned plates, or patterned belts.

3. The method of claim 1, wherein the method is performed as a continuous process using a flatbed laminating machine comprising a heating zone and cooling zone.

4. The method of claim 1, wherein the nonwoven material comprises a vertically lapped or cross-lapped thermally bonded nonwoven.

5. The method of claim 1, wherein a depth of the three-dimensional pattern in the one or more areas is at least about 1 mm.

6. The method of claim 1 wherein a depth of at least portions of the three-dimensional pattern in the one or more areas ranges from 1 mm to 25 mm

7. The method of claim 6 wherein the depth ranges from 5 mm to 15 mm.

8. A method for producing a patterned laminated multilayer material, comprising: preparing a layup comprising: at least one side substrate layer, a middle adhesive layer, and another side substrate layer comprising one or more layers of nonwoven material, wherein the nonwoven material comprises staple fibers together with heat-activatable binder fibers or binder material in the nonwoven structure; heating the layup to produce a heated layup, wherein heating melts the middle adhesive layer to form an adhesive suitable for bonding the at least one side substrate layer and the another side substrate layer together, wherein the heating softens or melts the heat-activatable binder fibers or binder material in the one or more layers of nonwoven material so as to allow the staple fibers to move relative each other in the heated nonwoven material; applying patterned pressure to the heated layup in one or more areas to form one or more patterns extending into a thickness of the layup; and cooling the layup so that the adhesive bonds the at least one side substrate layer and the another side substrate layer together and so that the binder fibers or binder material solidifies to form the one or more patterns into the one or more areas of a cooled layup, wherein the cooled layup has varying thicknesses across its one or more areas which correspond to the applied patterned pressure.

9. The method of claim 8, wherein the patterned pressure is applied by one or more engraved rollers, patterned plates, or patterned belts.

10. The method of claim 8, wherein the method is performed as a continuous process using a flatbed laminating machine comprising a heating zone and cooling zone.

11. The method of claim 8, wherein the patterned pressure is applied by a heated engraved roller that simultaneously heats, compresses, and patterns the layup, or by a cooled engraved roller when the layup has been preheated.

12. The method of claim 8, wherein the one side substrate layer is selected from the group consisting of knitted fabric, woven fabric, nonwoven fabric, artificial leather, and natural leather.

13. The method of claim 8, wherein a depth of the three-dimensional pattern in the one or more areas is at least about 1 mm.

14. The method of claim 8 wherein a depth of at least portions of the three-dimensional pattern in the one or more areas ranges from 1 mm to 25 mm

15. The method of claim 14 wherein the depth ranges from 5 mm to 15 mm.

Description

DESCRIPTION OF THE DRAWINGS

[0015] FIG. 1 is an isometric view of a 3-Dimensional pattern on a vertically lapped nonwoven.

[0016] FIG. 2 is an isometric view of a 3-Dimensional pattern on a laminated vertically lapped nonwoven.

[0017] FIG. 3 is an isometric view of an exemplary flatbed laminating machine.

DETAILED DESCRIPTION

Definitions

[0018] As used herein, the terms nonwoven, nonwoven fabric, and nonwoven material are used interchangeably. The nonwovens can be made with many different fiber blends including natural fibers and man-made fibers. The preferred nonwovens for this application are thermal-bonded vertically lapped nonwovens and thermal-bonded cross lapped nonwovens. Examples of fiber blends for nonwovens that could be used in the practice of this invention include but are not limited to the following: [0019] Elastomeric polyester binder fiber (6 denier64 mm): High shrink polyester fiber (1.4 denier51 mm): Low-melt polyester binder fiber (4 denier51 mm): Regular polyester fiber (6 denier51 mm)=25:20:10:45 [0020] Hollow conjugate polyester fiber (3 denier51 mm): Elastomeric polyester binder fiber (6 denier64 mm)=60:40 [0021] Hollow conjugate polyester fiber (15 denier51 mm): Elastomeric polyester binder fiber (6 denier51 mm)=60:40 [0022] Regular polyester fiber (15 denier51 mm): Low-melt polyester binder fiber (4 denier51 mm)=70:30 [0023] Hollow conjugate polyester fiber (3 denier51 mm): Elastomeric polyester binder fiber (6 denier64 mm): Low-melt polyester binder fiber (4 denier51 mm)=60:30:10 [0024] Regular polyester fiber (3 denier51 mm): Elastomeric polyester binder fiber (6 denier64 mm)=60:40 [0025] Hollow conjugate polyester fiber (3 denier51 mm): Hollow conjugate polyester fiber (15 denier51 mm): Elastomeric polyester binder fiber (6 denier64 mm): Low-melt polyester binder fiber (4 denier51 mm)=50:25:15:10 [0026] Viscose rayon fiber (3 denier64 mm): Low-melt polyester binder fiber (4 denier51 mm)=70:30 [0027] Flame retardant treated viscose rayon fiber (3 denier64 mm): Low-melt polyester binder fiber (4 denier51 mm)=80:20 [0028] Flame retardant treated viscose rayon fiber (3 denier64 mm): Low-melt polyester binder fiber (4 denier51 mm)=40:60 [0029] Silica-loaded flame retardant viscose rayon fiber (3 denier64 mm): Low-melt polyester binder fiber (4 denier51 mm)=70:30
Many other combinations of natural fibers, synthetic fibers, flame-retardant fibers, or functional fibers may be used depending on desired performance.

[0030] 1A nonwoven is a manufactured sheet, web, or batt of natural and/or man-made fibers or filaments that are bonded to each other by any of several means. Manufacturing of nonwoven products is well described in Nonwoven Textile Fabrics in Kirk-Othmer Encyclopedia of Chemical Technology, 3rd Ed., Vol. 16, July 1984, John Wiley & Sons, p. 72-124 and in Nonwoven Textiles, November 1988, Carolina Academic Press. Nonwovens are commercially available from a number of manufacturers. Vertical lapping may be performed using methods known in the art, e.g., as set forth in US 2008/0155787 and U.S. Pat. No. 7,591,049, each of which is incorporated herein by reference. Vertically lapped nonwovens are commercially available from a number of sources. A nonwoven is typically manufactured using any of a variety of staple fibers of interest together with binder fibers. The staple fibers can include silver fibers for providing antimicrobial resistance, basalt fibers, natural fibers (e.g., cotton, ramie, coir, hemp, abaca, sisal, kapok, jute, flax, linen, kenaf, coconut fiber, pineapple fiber, wool, cashmere, and silk), man-made fibers (e.g., polyester, nylon, acrylics, acetate, polyolefins, melamine fibers, elastomeric fibers, polybenzimidazole, aramid fibers, polyimide fibers, modacrylics, polyphenylene sulfide fibers, oxidized PAN fiber, carbon fibers, novoloid fibers, manufactured cellulosic fibers (e.g., rayon, lyocell, bamboo fiber, Tencel, and Modal), and manufactured fire-retardant (FR) cellulosic fibers (e.g., Visil., Anti-Fcell, Daiwabo's Corona fibers, Anti-Frayon, Sniace's FR rayon, and Lenzing FR)), etc. The binder fibers have a melting temperature that is below the melting or decomposition temperature of the one or more other fibers, e.g., binder fibers typically have a melting temperature of 80-150 C. (polyesters are typical examples of binder fibers used in the production of nonwovens (examples of elastic polyester binder fibers include ELK, E-PLEX, and EMF type high elastic LMF are commercially available from Teijin Limited, Toray Chemical Korea Inc., and Huvis Corporation, respectively)). Once the binder fibers are melted, they will generally tack along the outsides of the one or more staple fibers, and, on cooling, will harden to produce the nonwoven which is essentially a mass of the one or more staple fibers with adjacent fibers held together at various locations throughout the nonwoven by binder material which results from melting and re-hardening of the binder fibers. These nonwovens are often referred to as thermobonded nonwovens. The thermobonded nonwovens in the practice of this invention will have at least 5% by weight binder material, with up to 95% by weight of the one or more other fibers. Depending on the needs of the article manufacturer the binder material may constitute 5-50% by weight of the nonwoven with the remainder being the one or more other fibers, or the one more other fibers plus additional materials.

[0031] The term patterned includes, but is not limited to, three-dimensional structures such as indentations, raised features, and embossed textures that create variations in thickness and relief within the material.

General Overview

[0032] The present invention provides methods for producing patterned single-layer nonwovens and patterned laminated multilayer materials that include one or more layers of nonwoven. Patterns are formed by subjecting a heated nonwoven or multilayer assembly to patterned pressure, which is then fixed upon cooling of adhesive and/or binder materials to essentially lock the fibers of the nonwoven in place according to the patterned pressure applied. With multilayer structures which include an adhesive layer, the binder material in the nonwoven and the adhesive layer can be simultaneously melted or otherwise softened, and can then be simultaneously hardened on cooling. The processes may be conducted as batch operations or as continuous operations using industrial laminating equipment.

Single-Layer Nonwoven Embodiment

[0033] In one embodiment, the invention applies to a nonwoven material alone. The nonwoven comprises fibers bound by a heat-activatable binder fiber or binder resin. Examples of suitable fibers include natural fibers, synthetic fibers, or blends thereof. Preferred embodiments include vertically lapped or cross-lapped nonwovens that are thermally bonded with binder fibers such as low-melt polyester binder fibers, elastomeric polyester binder fibers, or polyolefins.

[0034] To impart a pattern, the nonwoven is heated to a temperature sufficient to activate the binder fibers, thereby permitting fiber mobility. While in this softened state, the nonwoven is subjected to patterned pressure from, for example, one or more engraved rollers, patterned plates, or patterned belts. In certain embodiments, the engraved roller may be either heated to simultaneously heat and pattern the nonwoven, or cooled when the nonwoven has been preheated. The areas under pressure deform, forming reduced-thickness and raised regions corresponding to the applied pattern. Upon cooling, the binder fibers resolidify and lock the pattern into the nonwoven, producing a durable patterned structure.

[0035] In certain embodiments, the depth of the three-dimensional pattern is at least about 1 mm, and may range from about 1 mm to about 25 mm, with a preferred range of about 5 mm to about 15 mm. FIG. 1 illustrates patterns on a vertically lapped nonwoven, with a depth difference of approximately 3 mm between the highest and lowest portions of the pattern. The depicted pattern extends downward into the thickness of the nonwoven; however, it will be recognized the same or a different pattern could be impressed on the bottom side of the layer upward into the thickness of the nonwoven.

Laminated Multilayer Embodiment

[0036] The invention may also be practiced with laminated multilayer assemblies which include one or more layers of nonwoven together with other layers.

[0037] An exemplary layup is prepared comprising at least three layers: [0038] One side substrate layer: This may include, but is not limited to, a knitted fabric, woven fabric, nonwoven fabric, artificial leather, natural leather, or other fabric-like layers. [0039] A middle adhesive layer: This layer may be selected from, but is not limited to, hot-melt adhesive webs, powders, or films. Suitable adhesive includes, but is not limited to copolyimide, copolyamide, copolyester, polyolefins, polypropylene, or polyurethane, with preferred melting points between about 60 C. and 230 C. Hot-melt adhesive webs are especially preferred. [0040] The other side substrate layer: Preferably this is a nonwoven (or a plurality of nonwoven layers), such as a vertically lapped or cross-lapped thermally bonded nonwoven, which include heat-activatable binder fibers or binder material which join the staple fibers of the nonwoven together.

[0041] In the exemplary embodiment, the adhesive layer bonds the substrates together when melted, while softening or melting of binder fibers or binder material in the nonwoven allow internal fiber movement during the lamination step. The layup is heated to melt the adhesive and activate the binder in the nonwoven. While still in the heated state, patterned pressure is applied to the layup using, for example, patterned plates, belts, or rollers. Upon cooling, the adhesive resolidifies to bond the substrates, and the binder material hardens to fix the three-dimensional or embossed pattern into the laminate.

[0042] In another embodiment, a patterned engraved roller may be used. The roller may be either heated or cooled depending on process conditions. When the laminate assembly is preheated, the engraved roller is preferably cooled so that patterning occurs during consolidation. In contrast, when the laminate assembly is not preheated, the engraved roller is preferably heated so that heating and patterning occur as the multilayer assembly passes through the roller nip.

[0043] In certain embodiments, the depth of the three-dimensional pattern is at least about 1 mm, and may range from about 1 mm to about 25 mm, with a preferred range of about 5 mm to about 15 mm.

[0044] FIG. 2 illustrates an example pattern formed in an assembly comprising a knit fabric (top), adhesive layer (middle), and vertically lapped nonwoven (bottom), with a depth difference of approximately 7 mm between the highest and lowest portions of the pattern.

Patterning Methods

Batch Processing Example

[0045] The layup or nonwoven is heated in an oven or by infrared heating to a desired temperature. The heated material is then compressed with patterned plates or under a patterned press during cooling. For example, an assembly heated to 140 C. for 7 minutes may be compressed with a diamond-patterned plate for 30 seconds during cooling, thereby forming diamond-shaped patterns in the material as shown in FIG. 1 and FIG. 2. The process would be applicable with any desired pattern, for example, with circles, stars, and other polygonal shapes, and for example, including forming into the surface corporate logos, desired images, and scenery, etc.

Continuous Processing Example

[0046] In a conventional flat lamination process, substrates to be laminated are fed between the top and bottom belts of a flatbed laminating machine. The thickness of the final laminated substrate is determined by the gap between the belts, but no patterned surface features are introduced.

[0047] In contrast, in a continuous embodiment of the present invention, the layup or nonwoven is preferably fed through a flatbed laminating machine, an example of which is shown in FIG. 3, comprising a heating zone and a cooling zone. Patterns are applied by, for example, patterned plates placed on top of the substrates while the substrates are conveyed through the laminating machine from the heating zone to the cooling zone, with the applied pressure controlled by adjusting the gap between the top and bottom belts. The plates may be fabricated from plastics, rubbers, ceramics, metals, or other materials capable of withstanding the pressure and temperature conditions of the process.

[0048] Patterns may also be applied by patterned endless belts that travel with the material. In one embodiment, the patterns are attached to either the top belt, the bottom belt, or both belts of the laminating machine. The patterns may be fabricated from plastics, rubbers, ceramics, metals, or other materials capable of withstanding the pressure and temperature conditions of the process.

[0049] Patterns may also be applied using patterned engraved rollers positioned at the exit of the laminating machine or used as a stand-alone setting. When the laminate assembly is preheatedsuch as when leaving the heating zone of the laminating machine while still hot but not yet cooled (The cooling zone of the laminating machine is turned off in this case)the engraved roller is preferably cooled so that patterning occurs during consolidation as the hot assembly passes through the cooled engraved roller. Conversely, when the laminate assembly has been cooled in the cooling zone, the engraved roller is preferably heated so that heating and patterning occur as the multilayer assembly passes through the roller nip.

[0050] In yet another embodiment, when at least three layers (e.g., a fabric, an adhesive web, and a nonwoven) are fed directly into a heated engraved roller in a stand-alone setting, the roller is maintained at an elevated temperature to induce both bonding between the layers and formation of the desired pattern. Heated engraved rollers thus simultaneously heat, compress, and pattern the material.

[0051] As noted above, patterns may be geometric (e.g., diamonds, hexagons), linear, discontinuous, or irregular.

Resulting Materials

[0052] The patterned nonwoven and laminated materials exhibit durable three-dimensional features that remain stable during use. In the case of nonwovens, the fibers are repositioned and locked in place by binder hardening. In the case of laminates, the top substrate conforms into the patterned indentations of the nonwoven layer, producing a visible and tactile three-dimensional effect.

[0053] In certain embodiments, the depth of the three-dimensional pattern is at least about 1 mm, measured as the distance between the highest and lowest portions of the pattern. The pattern depth may range from about 1 mm to about 25 mm, and is preferably between about 5 mm and about 15 mm, depending on the desired application.

[0054] The patterned structures may enhance aesthetics, cushioning, or other performance properties, making them suitable for applications such as mattresses, upholstered furniture, automotive interiors, technical textiles, and specialty industrial products.

EXAMPLES

Example 1: Laminated Multilayer with Hexagonal Pattern (Batch Process)

[0055] An assembly of three layers was prepared consisting of: a knitted fabric as the first substrate, a hot-melt adhesive web as the middle adhesive layer, and a vertically lapped nonwoven material as the second substrate.

[0056] The assembly was heated in an oven at 140 C. for 7 minutes. Immediately after removal from the oven, a metal plate having a repeated hexagonal pattern was pressed onto the heated layup for 30 seconds during cooling.

[0057] As the adhesive resolidified and the binder fibers in the nonwoven hardened, the layup exhibited durable three-dimensional hexagonal patterns. The knitted fabric adhered securely to the nonwoven, conforming into the indented regions, while the nonwoven retained reduced thickness in the compressed areas. In this embodiment, the depth of the pattern was approximately 8 mm.

[0058] The resulting material demonstrated stable three-dimensional patterns suitable for furniture and mattress applications.

Example 2: Laminated Multilayer with Line Pattern (Engraved Roller, Continuous Process)

[0059] An assembly of three layers was prepared consisting of: a knitted fabric as the first substrate, a hot-melt adhesive web as the middle adhesive layer, and a cross-lapped nonwoven material as the second substrate.

[0060] The assembly was passed through a heated engraved roller maintained at a surface temperature of 160 C. and a line speed of 2 m/min. The engraved roller contained a repeating line pattern with an engraving depth of approximately 5 mm.

[0061] During passage, the heat melted the hot-melt adhesive and activated the binder fibers in the nonwoven, permitting fiber mobility and bonding of the layers. The engraved roller applied patterned pressure, compacting the assembly in the engraved line regions. As the laminate exited the roller and cooled, the adhesive resolidified to bond the substrates, and the binder fibers hardened to fix the three-dimensional pattern.

[0062] The resulting laminated multilayer material exhibited a stable three-dimensional line pattern with alternating thick and thin regions, providing improved surface texture and structural aesthetics compared to an unpatterned laminate.

Example 3: Single-Layer Nonwoven with Hexagonal Pattern (Flatbed Lamination Machine with Patterned Plate, Continuous Process)

[0063] A vertically lapped nonwoven was continuously fed into a flatbed laminating machine comprising a heating zone and a cooling zone. A patterned plate having a repeating hexagonal design was placed on the nonwoven as it passed between the upper and lower belts of the laminating machine. The pressure was controlled by adjusting the gap between the belts.

[0064] The heating zone of the flatbed laminating machine was set at 130 C., and the cooling zone was set at 30 C.

[0065] In the heating zone, the binder fibers in the nonwoven were activated, permitting fiber mobility. While still in the heated state, the patterned plate pressed the nonwoven, creating localized compaction in the hexagonal regions. In the cooling zone, the binder fibers resolidified, locking the three-dimensional hexagonal pattern into the nonwoven.

[0066] The resulting single-layer nonwoven exhibited a stable three-dimensional hexagonal pattern with alternating thick and thin regions, providing improved surface texture and structural aesthetics compared to an unpatterned nonwoven.

Example 4: Continuous Laminated Multilayer with Belt-Imprinted Pattern

[0067] A three-layer assembly was prepared comprising: a knitted fabric (top layer), a hot-melt adhesive film (middle adhesive layer), and a vertically lapped nonwoven (bottom layer).

[0068] The layers were continuously fed into a flatbed laminating machine equipped with a heating zone at 130 C., a patterned top endless belt with a rectangular grid design, and a cooling zone at 30 C.

[0069] As the three-layer assembly entered the heating zone, the adhesive melted and the binder fibers in the nonwoven softened. While in this heated state, the endless belts pressed the layup, with the top belt carrying the rectangular grid pattern and the bottom belt being smooth. This pressure formed a rectangular grid across the entire surface. The laminate then passed through the cooling zone, where the adhesive and binder fibers resolidified, locking the three-dimensional rectangular grid pattern into the structure.

[0070] The resulting laminate exhibited a stable three-dimensional rectangular grid pattern, with the knitted surface conforming into the indented regions of the underlying nonwoven. This structure provided improved surface texture and structural aesthetics compared to a flat laminate. Besides rectangles and diamonds, any geometric pattern can be imparted to the multilayer structure according to the invention.