Method for improving the retention of loft agents using bicomponent fibers

Abstract

A method for forming a lightweight, reinforced thermoplastic core layer and an article including the core layer is described. In some examples, the method uses a combination of thermoplastic material, reinforcing fibers, and bicomponent fibers to enhance the retention of lofting agents in the core layer. The process allows for the use of less material while providing sufficient loft capacity in the final formed core layer.

Description

[Technical field]

[0001] (Priority Application) This application claims priority to and the benefit of U.S. Provisional Patent Application No. 62 / 800,307, filed February 1, 2019, the entire disclosure of which is incorporated herein by reference.

[0002] Certain embodiments relate to methods for improving the retention of loft agents in thermoplastic composite articles. More specifically, some examples describe methods used to produce thermoplastic composite articles having enhanced retention of loft agents within the thermoplastic composite articles. [Background technology]

[0003] Certain automotive and architectural applications often use thermoplastic-based materials in place of traditional steel or metal articles. The use of thermoplastic-based materials can give rise to unique considerations that do not arise with steel or metal articles. Summary of the Invention

[0004] Certain embodiments are described herein to illustrate several configurations and methods for producing lightweight reinforced thermoplastic composite articles.

[0005] In one aspect, a method for producing a porous composite article includes combining inorganic reinforcing fibers, organic reinforcing fibers, and a thermoplastic material in a liquid to produce an aqueous foam, the organic reinforcing fibers including a core-shell configuration, the shell material in the shell of the core-shell configuration including a melting point substantially similar to the melting point of the thermoplastic material, and the core material in the core of the core-shell configuration including a melting point at least 20 degrees Celsius higher than the melting point of the thermoplastic material. The method may also include depositing the aqueous foam onto a moving wire screen. The method may also include removing liquid from the deposited aqueous foam on the moving wire screen to form an open-celled web formed from the thermoplastic material, the inorganic reinforcing fibers, and the organic reinforcing fibers. The method may also include depositing a lofting agent onto the formed web. The method may also include compressing the formed web including the deposited lofting agent to provide a porous composite article.

[0006] In a particular example, the method includes drawing the lofting agent into voids in the formed web using negative pressure provided to a bottom surface of the formed web during deposition of the lofting agent. In another example, at least 50% of the deposited lofting agent is retained by the formed web. In some embodiments, the organic reinforcing fibers include a shell comprising a polyolefin and a core comprising a polyester. In another embodiment, the polyolefin comprises polyethylene. In a particular example, the polyethylene is linear low density polyethylene. For example, linear low density polyethylene has a density of about 0.91 g / cm. 3 ~Approx. 0.94g / cm 3 In some examples, the polyester includes one or more of polyethylene terephthalate, polybutylene terephthalate, and polynaphthalene terephthalate.

[0007] In other examples, the organic reinforcing fibers include a shell that includes a polyolefin and a core that includes a polyamide. In certain cases, the polyolefin includes polyethylene. In some examples, the polyethylene is linear low density polyethylene. For example, linear low density polyethylene has a density of about 0.91 g / cm. 3~Approx. 0.94g / cm 3 In some examples, the polyamide comprises a copolyamide. In some examples, the polyamide comprises a nylon.

[0008] In some embodiments, the thermoplastic material comprises a polyolefin, the inorganic reinforcing fibers comprise glass fibers, the organic reinforcing fibers comprise a polyolefin in the shell and a polyester in the core, and the loft agent comprises expandable microspheres. In some examples, the thermoplastic material is polypropylene, the polyolefin of the shell comprises polyethylene, and the polyester of the core comprises polyethylene terephthalate.

[0009] In other embodiments, the thermoplastic material comprises a polyolefin, the inorganic reinforcing fibers comprise glass fibers, the organic reinforcing fibers comprise a polyolefin in the shell and a polyamide in the core, and the loft agent comprises expandable microspheres. In some examples, the thermoplastic material is polypropylene, the polyolefin of the shell comprises polyethylene, and the polyamide of the core comprises nylon.

[0010] In some examples, the thermoplastic material includes polypropylene, the inorganic reinforcing fibers include glass fibers, the organic reinforcing fibers include polyethylene in the shell and polyester in the core, the melting point of the polyester in the core is at least 50 degrees Celsius higher than the melting point of the polyethylene in the shell, the loft agent includes expandable microspheres, and the porous thermoplastic composite article includes a porosity of 20% to 80%.

[0011] In a particular example, the thermoplastic material includes polypropylene, the inorganic reinforcing fibers include glass fibers, the organic reinforcing fibers include polyethylene in the shell and polyamide in the core, the melting point of the polyamide in the core is at least 50 degrees Celsius higher than the melting point of the polyethylene in the shell, the loft agent includes expandable microspheres, and the porous thermoplastic composite article includes a porosity of 20% to 80%.

[0012] In another aspect, a method of producing a porous composite article includes combining inorganic reinforcing fibers, organic reinforcing fibers, and a thermoplastic material in a liquid to produce an aqueous foam, the organic reinforcing fibers including a side-by-side arrangement, a first fiber in the side-by-side arrangement includes a melting point substantially similar to the melting point of the thermoplastic material, and a second fiber in the side-by-side arrangement includes a melting point at least 20 degrees Celsius higher than the melting point of the thermoplastic material. The method may also include depositing the aqueous foam on a moving wire screen. The method may also include removing liquid from the deposited aqueous foam on the moving wire screen to form an open-celled web formed from the thermoplastic material, the inorganic reinforcing fibers, and the organic reinforcing fibers. The method may also include depositing a lofting agent on the formed web. The method may also include compressing the formed web including the deposited lofting agent to provide a porous composite article.

[0013] In certain embodiments, negative pressure can be provided to the bottom surface of the formed web during deposition of the lofting agent to draw the lofting agent into voids in the formed web. In some examples, at least 50% of the deposited lofting agent is retained by the formed web. In some examples, a first fiber of the organic reinforcing fibers comprises a polyolefin and a second fiber of the organic reinforcing fibers comprises a polyester. In other examples, the polyolefin comprises polyethylene. In some examples, the polyethylene is linear low density polyethylene. For example, linear low density polyethylene has a density of about 0.91 g / cm. 3 ~Approx. 0.94g / cm 3 In some examples, the polyester includes one or more of polyethylene terephthalate, polybutylene terephthalate, and polynaphthalene terephthalate.

[0014] In a particular example, a first fiber of the organic reinforcing fibers comprises a polyolefin and a second fiber of the organic reinforcing fibers comprises a polyamide. In some cases, the polyolefin comprises polyethylene. In other examples, the polyethylene is linear low density polyethylene. In a particular example, the linear low density polyethylene has a density of about 0.91 g / cm 3~Approx. 0.94g / cm 3 In some embodiments, the polyamide comprises a copolyamide. In some examples, the polyamide comprises a nylon.

[0015] In other examples, the thermoplastic material comprises a polyolefin, the inorganic reinforcing fibers comprise glass fibers, the organic reinforcing fibers comprise a first fiber comprising a polyolefin and a second fiber comprising a polyester, and the loft agent comprises expandable microspheres. In some examples, the thermoplastic material is polypropylene, the polyolefin of the first fiber comprises polyethylene, and the polyester of the second fiber comprises polyethylene terephthalate.

[0016] In certain embodiments, the thermoplastic material comprises a polyolefin, the inorganic reinforcing fibers comprise glass fibers, the organic reinforcing fibers comprise a first fiber comprising a polyolefin and a second fiber comprising a polyamide, and the loft agent comprises expandable microspheres. In some examples, the thermoplastic material is polypropylene, the polyolefin of the first fiber comprises polyethylene, and the polyamide of the second fiber comprises nylon.

[0017] In a particular embodiment, the thermoplastic material comprises polypropylene, the inorganic reinforcing fibers comprise glass fibers, the organic reinforcing fibers comprise first fibers comprising polyethylene and second fibers comprising polyester, a melting point of the polyester in the second fibers is at least 50 degrees Celsius higher than a melting point of the polyethylene in the first fibers, the loft agent comprises expandable microspheres, and the porous thermoplastic composite article comprises a porosity of 20% to 80%.

[0018] In another embodiment, the thermoplastic material comprises polypropylene, the inorganic reinforcing fibers comprise glass fibers, the organic reinforcing fibers comprise first fibers comprising polyethylene and second fibers comprising polyamide, a melting point of the polyamide in the second fibers is at least 50 degrees Celsius higher than a melting point of the polyethylene in the first fibers, the loft agent comprises expandable microspheres, and the porous thermoplastic composite article comprises a porosity of 20% to 80%.

[0019] In another embodiment, a method for producing a porous composite article includes combining reinforcing fibers, bicomponent fibers, and a thermoplastic material in a liquid to produce an aqueous foam, the bicomponent fibers including a core-shell configuration, the shell material in the shell of the core-shell configuration includes a melting point substantially similar to the melting point of the thermoplastic material, and the core material in the core of the core-shell configuration includes a melting point at least 20 degrees Celsius higher than the melting point of the thermoplastic material. In some examples, the method includes depositing the aqueous foam onto a moving wire screen. In other examples, the method includes removing liquid from the aqueous foam deposited on the moving wire screen to form an open-celled web formed from the thermoplastic material, the reinforcing fibers, and the bicomponent fibers. The method may also include depositing a lofting agent onto the formed web. The method may also include compressing the formed web including the deposited lofting agent to provide a porous composite article.

[0020] In an additional aspect, a method of producing a porous composite article includes combining reinforcing fibers, bicomponent fibers, and a thermoplastic material in a liquid to produce an aqueous foam, the bicomponent fibers including a side-by-side arrangement, a first fiber in the side-by-side arrangement includes a melting point substantially similar to the melting point of the thermoplastic material, and a second fiber in the side-by-side arrangement includes a melting point at least 20 degrees Celsius higher than the melting point of the thermoplastic material. In some examples, the method includes depositing the aqueous foam on a moving wire screen. The method may also include removing liquid from the deposited aqueous foam on the moving wire screen to form an open-celled web formed from the thermoplastic material, the reinforcing fibers, and the bicomponent fibers. The method may include depositing a lofting agent on the formed web. The method may also include compressing the formed web including the deposited lofting agent to provide a porous composite article.

[0021] In another aspect, a method for producing a porous composite article includes combining inorganic reinforcing fibers, organic reinforcing fibers, a thermoplastic material, and a lofting agent in a liquid to produce an aqueous foam, the organic reinforcing fibers include a core-shell configuration, the shell material in the shell of the core-shell configuration includes a melting point substantially similar to the melting point of the thermoplastic material, and the core material in the core of the core-shell configuration includes a melting point at least 20 degrees Celsius higher than the melting point of the thermoplastic material. The method may also include depositing the aqueous foam on a moving wire screen. The method may also include removing liquid from the deposited aqueous foam on the moving wire screen to form an open-celled web formed from the thermoplastic material, the inorganic reinforcing fibers, and the organic reinforcing fibers, the formed web including the lofting agent trapped in the web. The method may also include compressing the formed web including the deposited lofting agent to provide a porous composite article.

[0022] In another aspect, a method of producing a porous composite article includes combining inorganic reinforcing fibers, organic reinforcing fibers, a thermoplastic material, and a lofting agent in a liquid to produce an aqueous foam, the organic reinforcing fibers include a side-by-side arrangement, a first fiber in the side-by-side arrangement includes a melting point substantially similar to the melting point of the thermoplastic material, and a second fiber in the side-by-side arrangement includes a melting point at least 20 degrees Celsius higher than the melting point of the thermoplastic material. The method may also include depositing the aqueous foam on a moving wire screen. The method may also include removing liquid from the deposited aqueous foam on the moving wire screen to form an open-celled web formed from the thermoplastic material, the inorganic reinforcing fibers, and the organic reinforcing fibers, the formed web including the lofting agent trapped in the web. The method may also include compressing the formed web including the deposited lofting agent to provide a porous composite article.

[0023] In an additional aspect, a method of producing a porous composite article includes combining reinforcing fibers, bicomponent fibers, a thermoplastic material, and a lofting agent in a liquid to produce an aqueous foam, the bicomponent fibers including a core-shell configuration, the shell material in the shell of the core-shell configuration including a melting point substantially similar to the melting point of the thermoplastic material, and the core material in the core of the core-shell configuration including a melting point at least 20 degrees Celsius higher than the melting point of the thermoplastic material. The method may also include depositing the aqueous foam onto a moving wire screen. The method may also include removing liquid from the deposited aqueous foam on the moving wire screen to form an open-celled web formed from the thermoplastic material, the reinforcing fibers, and the bicomponent fibers, the formed web including the lofting agent trapped in the web, and compressing the formed web including the deposited lofting agent to provide a porous composite article.

[0024] In another aspect, a method of producing a porous composite article includes combining reinforcing fibers, bicomponent fibers, a thermoplastic material, and a lofting agent in a liquid to produce an aqueous foam, the bicomponent fibers including a side-by-side arrangement, a first fiber in the side-by-side arrangement includes a melting point substantially similar to the melting point of the thermoplastic material, and a second fiber in the side-by-side arrangement includes a melting point at least 20 degrees Celsius higher than the melting point of the thermoplastic material. The method may also include depositing the aqueous foam onto a moving wire screen. The method may also include removing liquid from the aqueous foam deposited on the moving wire screen to form an open-celled web formed from the thermoplastic material, the reinforcing fibers, and the bicomponent fibers, the formed web including the lofting agent trapped in the web. The method may also include compressing the formed web including the deposited lofting agent to provide a porous composite article.

[0025] Additional aspects, examples, embodiments, and configurations are described in more detail below.

[0026] Particular aspects, embodiments, and examples are described below with reference to the accompanying figures. [Brief description of the drawings]

[0027] [Figure 1] 1 is an illustration of a core-shell fiber arrangement, with some examples. [Diagram 2] 1 is an illustration of a parallel fiber arrangement, according to certain embodiments. [Figure 3A] 14A-14C are illustrations of parallel fiber arrangements with shells, according to several examples. [Figure 3B] 14A-14C are illustrations of parallel fiber arrangements with shells, according to several examples. [Figure 4] 1 is an illustration of a core layer with some examples. [Diagram 5] 1 illustrates a process that can be used to produce a core layer, according to some examples. [Figure 6] 1 illustrates another process that can be used to produce a core layer, according to a particular example. [Figure 7] 1 is an illustration of an article including a core layer and a skin layer, according to some examples. [Figure 8] 1 is an illustration of an article including a core layer and two skin layers, according to some examples. [Figure 9] 1 is an illustration of an article including a core layer, a skin layer, and a decorative layer, according to some examples. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0028] It will be appreciated by those skilled in the art that the depictions and layers in the figures are provided for illustrative purposes only, and no specific thicknesses, materials, dimensions, etc. are intended to be implied or required unless expressly stated otherwise in the description herein in connection with that specific illustration.

[0029] Specific examples of how the retention of lofting agent can be enhanced using a combination of thermoplastic materials and different fibers are described herein. In some examples, the retention of lofting agent can be at least 50% by volume or more in the presence of different fibers and thermoplastic materials. The ability to retain more lofting agent can reduce the amount of material required, the cost to produce the article, and provide better distribution of the lofting agent in the article.

[0030] In certain embodiments, the articles produced herein are described in certain cases as lightweight reinforced thermoplastic (LWRT) articles. In general, the articles include a core layer including a web formed from a thermoplastic material, a reinforcing fiber, and a bicomponent fiber. The presence of the combined materials can aid in the retention of lofting agents, such as, for example, microsphere lofting agents, in the web of the core layer.

[0031] In certain configurations, the bicomponent fibers of the core layer may include two or more different materials that can be arranged in many different ways. For example, the bicomponent fibers can be configured as a core-shell arrangement, a side-by-side arrangement, or a combination of these arrangements with the shell surrounding the side-by-side arrangement of the fibers. The different fibers can be extruded, coextruded, drawn, or produced in a manner similar to that used to produce the fibers. In some examples, the produced fibers can be coated with another material to provide a shell around the core fibers. When there are multiple fibers in the shell, the fibers can be coaxial, e.g., left untwisted, or crossed or twisted as desired.

[0032] Referring to FIG. 1, an illustration showing a cross section through a core-shell arrangement of a bicomponent fiber is shown. The bicomponent fiber 100 includes a core material 110 surrounded by a shell material 120. Although each of the components 110, 120 may not be truly fibers, the core 110 and shell 120 materials together form a fiber. Alternatively, each of the materials 110, 120 can be considered a fiber. The shell material 120 does not have to completely surround or be symmetrical around the core material 110. Without wishing to be bound by any particular theory, the shell material 120 is selected to be compatible with the thermoplastic material, e.g., thermoplastic resin, used to generate the core layer. For example, the melting point of the shell material 120 can be about the same or the same as the melting point of the thermoplastic material of the core layer. In some examples, the melting points of the shell material 120 and the thermoplastic material can differ by about 1 degree to about 10 degrees Celsius and the materials can still be considered compatible.

[0033] In certain embodiments, the core material 110 typically comprises a higher melting point than the shell material 120 and the thermoplastic material. For example, when the core layer is formed, the shell material 120 and the thermoplastic material may be melted or softened to form the web of the core layer. The core material 110 typically remains solid and does not melt or soften to any substantial extent during processing of the material to form the core layer.

[0034] In certain examples, the melting point of the core material 110 is at least 15 degrees Celsius higher than the melting point of the shell material 120 or the melting point of the thermoplastic material. In some examples, the melting point of the core material 110 is at least 20 degrees Celsius higher than the melting point of the shell material 120 or the melting point of the thermoplastic material. In other examples, the melting point of the core material 110 is at least 25 degrees Celsius higher than the melting point of the shell material 120 or the melting point of the thermoplastic material. In other examples, the melting point of the core material 110 is at least 30 degrees Celsius higher than the melting point of the shell material 120 or the melting point of the thermoplastic material. In certain examples, the melting point of the core material 110 is at least 35 degrees Celsius higher than the melting point of the shell material 120 or the melting point of the thermoplastic material. In certain embodiments, the melting point of the core material 110 is at least 40 degrees Celsius higher than the melting point of the shell material 120 or the melting point of the thermoplastic material. In other embodiments, the melting point of the core material 110 is at least 45 degrees Celsius higher than the melting point of the shell material 120 or the melting point of the thermoplastic material. In other embodiments, the melting point of the core material 110 is at least 50 degrees Celsius higher than the melting point of the shell material 120 or the melting point of the thermoplastic material.

[0035] In certain configurations, the materials present in the shell 120 and the core 110 are not the same material. For example, the shell material 120 may include a polyolefin and the core material 110 may include a material having a melting point higher than the melting point of the polyolefin of the shell material 120. In other cases, the core material 110 may include a polyester, polyamide, or copolyamide and the shell material 120 may include a material having a melting point lower than the melting point of the polyester, polyamide, or copolyamide in the core material 110. In additional examples, the shell material 120 may include a polyolefin and the core material 110 may include a polyester, polyamide, or copolyamide. In some examples, the shell material 120 includes a polyolefin and the core material 110 includes a polyester. In other examples, the shell material 120 includes a polyolefin and the core material 110 includes a polyamide. In some examples, the shell material 120 includes a polyolefin and the core material includes a copolyamide.

[0036] In some examples, the polyolefin of the shell material 120 may be polyethylene, polypropylene, or other olefin-based polymers and copolymers. In some embodiments, the polyolefin material of the shell 120 may be considered a linear low density polyolefin. For example, the polyolefin material of the shell 120 may be linear low density polyethylene (LLDPE) or low density polyethylene (LDPE). While the exact material properties may vary, linear low density polyethylene has a viscosity of approximately 0.91 g / cm 3 ~Approx. 0.94g / cm 3 In some examples, the melting point of the LLDPE or LDPE may be at least 15 degrees Celsius lower than the melting point of the core material 110. In certain examples, the melting point of the LLDPE or LDPE may be at least 20 degrees Celsius lower than the melting point of the core material 110. In other examples, the melting point of the LLDPE or LDPE may be at least 25 degrees Celsius lower than the melting point of the core material 110. In certain examples, the melting point of the LLDPE or LDPE may be at least 30 degrees Celsius lower than the melting point of the core material 110. In other examples, the melting point of the LLDPE or LDPE may be at least 35 degrees Celsius lower than the melting point of the core material 110. In certain examples, the melting point of the LLDPE or LDPE may be at least 40 degrees Celsius lower than the melting point of the core material 110. In other examples, the melting point of the LLDPE or LDPE may be at least 45 degrees Celsius lower than the melting point of the core material 110. In some examples, the melting point of the LLDPE or LDPE may be at least 50 degrees Celsius lower than the melting point of the core material 110 .

[0037] In other examples, the core material 110 may include a polyester that includes terephthalate monomer units. For example, the polyester may be polyethylene terephthalate, polybutylene terephthalate, or polynaphthalene terephthalate. In certain examples, the melting point of the polyester that includes terephthalate monomer units in the core material 110 may be at least 15 degrees higher than the melting point of the material in the shell material 120. In some examples, the melting point of the polyester that includes terephthalate monomer units in the core material 110 may be at least 20 degrees higher than the melting point of the material in the shell material 120. In certain examples, the melting point of the polyester that includes terephthalate monomer units in the core material 110 may be at least 25 degrees higher than the melting point of the material in the shell material 120. In other examples, the melting point of the polyester that includes terephthalate monomer units in the core material 110 may be at least 30 degrees higher than the melting point of the material in the shell material 120. In certain examples, the melting point of the polyester that includes terephthalate monomer units in the core material 110 may be at least 35 degrees higher than the melting point of the material in the shell material 120. In some examples, the melting point of the polyester including terephthalate monomer units in the core material 110 may be at least 40 degrees higher than the melting point of the material in the shell material 120. In other examples, the melting point of the polyester including terephthalate monomer units in the core material 110 may be at least 45 degrees higher than the melting point of the material in the shell material 120. In additional examples, the melting point of the polyester including terephthalate monomer units in the core material 110 may be at least 50 degrees higher than the melting point of the material in the shell material 120.

[0038] In some embodiments, the core material 110 may include a polyamide or copolyamide. For example, the core material 110 may include nylon, nylon 66, aramid, polyesteramide, polyetheramide, polyetheresteramide, or other polyamide-containing copolymer. In certain examples, the melting point of the polyamide or copolyamide in the core material 110 may be at least 15 degrees higher than the melting point of the material in the shell material 120. In some examples, the melting point of the polyamide or copolyamide in the core material 110 may be at least 20 degrees higher than the melting point of the material in the shell material 120. In certain examples, the melting point of the polyamide or copolyamide in the core material 110 may be at least 25 degrees higher than the melting point of the material in the shell material 120. In other examples, the melting point of the polyamide or copolyamide in the core material 110 may be at least 30 degrees higher than the melting point of the material in the shell material 120. In certain examples, the melting point of the polyamide or copolyamide in the core material 110 may be at least 35 degrees higher than the melting point of the material in the shell material 120. In some examples, the melting point of the polyamide or copolyamide in core material 110 may be at least 40 degrees higher than the melting point of the material in shell material 120. In other examples, the melting point of the polyamide or copolyamide in core material 110 may be at least 45 degrees higher than the melting point of the material in shell material 120. In additional examples, the melting point of the polyamide or copolyamide in core material 110 may be at least 50 degrees higher than the melting point of the material in shell material 120.

[0039] In certain examples, the shell material 120 may include a polyethylene, such as LLDPE, and the core material 110 may include a polyester or a polyamide. For example, the core material 110 may include nylon, polyethylene terephthalate, polybutylene terephthalate, polynaphthalene terephthalate, or a combination thereof. In certain examples, the melting point of the polyester or polyamide in the core material 110 may be at least 15 degrees higher than the melting point of the polyethylene material in the shell material 120. In some examples, the melting point of the polyester or polyamide in the core material 110 may be at least 20 degrees higher than the melting point of the polyethylene material in the shell material 120. In certain examples, the melting point of the polyester or polyamide in the core material 110 may be at least 25 degrees higher than the melting point of the polyethylene material in the shell material 120. In other examples, the melting point of the polyester or polyamide in the core material 110 may be at least 30 degrees higher than the melting point of the polyethylene material in the shell material 120. In certain examples, the melting point of the polyester or polyamide in the core material 110 may be at least 35 degrees higher than the melting point of the polyethylene material in the shell material 120. In some examples, the melting point of the polyester or polyamide in the core material 110 may be at least 40 degrees higher than the melting point of the polyethylene material in the shell material 120. In other examples, the melting point of the polyester or polyamide in the core material 110 may be at least 45 degrees higher than the melting point of the polyethylene material in the shell material 120. In additional examples, the melting point of the polyester or polyamide in the core material 110 may be at least 50 degrees higher than the melting point of the polyethylene material in the shell material 120.

[0040] In other cases, the bicomponent fibers present in the LWRT article may include a left-right fiber arrangement. Referring to FIG. 2, an illustration showing a cross section through a side-by-side fiber arrangement of a bicomponent fiber is shown. The bicomponent fiber 200 includes a first fiber 210 arranged on the side of a second fiber 220. The fibers 210, 220 may be twisted around each other or remain untwisted and run approximately coaxially with each other throughout the fiber 200. While not wishing to be bound by any particular theory, the melting point of the material of one of the fibers 210, 220 is typically approximately the same or the same as the melting point of the thermoplastic material of the core layer. In some instances, the melting points of the fibers 210, 220 and one of the thermoplastic materials may differ by about 1 degree to about 10 degrees Celsius and the materials can still be considered compatible.

[0041] In certain embodiments, the fibers 210 typically include a higher melting point than the other fibers 220 and the thermoplastic material. For example, when the core layer is formed, the fibers 220 and the thermoplastic material may be melted or softened to form the web of the core layer. The fibers 210 typically remain solid and do not melt and soften to any substantial extent during processing of the material to form the core layer. In certain examples, the melting point of the fibers 210 is at least 15 degrees Celsius higher than the melting point of the fibers 220 or the melting point of the thermoplastic material. In some examples, the melting point of the fibers 210 is at least 20 degrees Celsius higher than the melting point of the fibers 220 or the melting point of the thermoplastic material. In other examples, the melting point of the fibers 210 is at least 25 degrees Celsius higher than the melting point of the fibers 220 or the melting point of the thermoplastic material. In other examples, the melting point of the fibers 210 is at least 30 degrees Celsius higher than the melting point of the fibers 220 or the melting point of the thermoplastic material. In certain instances, the melting point of the fibers 210 is at least 35 degrees Celsius higher than the melting point of the fibers 220 or the melting point of the thermoplastic material. In certain embodiments, the melting point of the fibers 210 is at least 40 degrees Celsius higher than the melting point of the fibers 220 or the melting point of the thermoplastic material. In other embodiments, the melting point of the fibers 210 is at least 45 degrees Celsius higher than the melting point of the fibers 220 or the melting point of the thermoplastic material. In other embodiments, the melting point of the fibers 210 is at least 50 degrees Celsius higher than the melting point of the fibers 220 or the melting point of the thermoplastic material.

[0042] In certain configurations, the materials present in fibers 210, 220 are not the same material. For example, fiber 220 may include a polyolefin and fiber 210 may include a material having a melting point higher than the melting point of the polyolefin of shell material 120. In other cases, fiber 210 may include a polyester, polyamide, or copolyamide and fiber 220 may include a material having a melting point lower than the melting point of the polyester, polyamide, or copolyamide in fiber 210. In additional examples, fiber 220 may include a polyolefin and fiber 210 may include a polyester, polyamide, or copolyamide. In some examples, fiber 220 includes a polyolefin and fiber 210 includes a polyester. In other examples, fiber 220 includes a polyolefin and fiber 210 includes a polyamide. In some examples, fiber 220 includes a polyolefin and fiber 210 includes a copolyamide.

[0043] In some examples, the polyolefin of the fibers 220 may be polyethylene, polypropylene, or other olefin-based polymers and copolymers. In some embodiments, the polyolefin material of the fibers 220 may be considered a linear low density polyolefin. For example, the polyolefin material of the fibers 220 may be linear low density polyethylene (LLDPE) or low density polyethylene (LDPE). While the exact material properties may vary, linear low density polyethylene has a viscosity of about 0.91 g / cm 3 ~Approx. 0.94g / cm 3In some examples, the melting point of the LLDPE or LDPE may be at least 15 degrees Celsius lower than the melting point of the fibers 210. In certain examples, the melting point of the LLDPE or LDPE may be at least 20 degrees Celsius lower than the melting point of the fibers 210. In other examples, the melting point of the LLDPE or LDPE may be at least 25 degrees Celsius lower than the melting point of the fibers 210. In certain examples, the melting point of the LLDPE or LDPE may be at least 30 degrees Celsius lower than the melting point of the core material 110. In other examples, the melting point of the LLDPE or LDPE may be at least 35 degrees Celsius lower than the melting point of the fibers 210. In certain examples, the melting point of the LLDPE or LDPE may be at least 40 degrees Celsius lower than the melting point of the fibers 210. In other examples, the melting point of the LLDPE or LDPE may be at least 45 degrees Celsius lower than the melting point of the fibers 210. In some examples, the melting point of the LLDPE or LDPE may be at least 50 degrees Celsius lower than the melting point of the fibers 210.

[0044] In other examples, the fiber 210 may include a polyester that includes terephthalate monomer units. For example, the polyester may be polyethylene terephthalate, polybutylene terephthalate, or polynaphthalene terephthalate. In certain examples, the melting point of the polyester that includes terephthalate monomer units in the fiber 210 may be at least 15 degrees higher than the melting point of the material in the fiber 220. In some examples, the melting point of the polyester that includes terephthalate monomer units in the fiber 210 may be at least 20 degrees higher than the melting point of the material in the fiber 220. In certain examples, the melting point of the polyester that includes terephthalate monomer units in the fiber 210 may be at least 25 degrees higher than the melting point of the material in the fiber 220. In other examples, the melting point of the polyester that includes terephthalate monomer units in the fiber 210 may be at least 30 degrees higher than the melting point of the material in the fiber 220. In certain examples, the melting point of the polyester that includes terephthalate monomer units in the fiber 210 may be at least 35 degrees higher than the melting point of the material in the fiber 220. In some examples, the melting point of the polyester including terephthalate monomer units in fibers 210 may be at least 40 degrees higher than the melting point of the material in fibers 220. In other examples, the melting point of the polyester including terephthalate monomer units in fibers 210 may be at least 45 degrees higher than the melting point of the material in fibers 220. In an additional example, the melting point of the polyester including terephthalate monomer units in fibers 210 may be at least 50 degrees higher than the melting point of the material in fibers 220.

[0045] In some embodiments, the fiber 210 may include a polyamide or copolyamide. For example, the fiber 210 may include nylon, nylon 66, aramid, polyesteramide, polyetheramide, polyetheresteramide, or other polyamide-containing copolymer. In certain examples, the melting point of the polyamide or copolyamide in the fiber 210 may be at least 15 degrees higher than the melting point of the material in the fiber 220. In some examples, the melting point of the polyamide or copolyamide in the fiber 210 may be at least 20 degrees higher than the melting point of the material in the fiber 220. In certain examples, the melting point of the polyamide or copolyamide in the fiber 210 may be at least 25 degrees higher than the melting point of the material in the fiber 220. In other examples, the melting point of the polyamide or copolyamide in the fiber 210 may be at least 30 degrees higher than the melting point of the material in the fiber 220. In certain examples, the melting point of the polyamide or copolyamide in the fiber 210 may be at least 35 degrees higher than the melting point of the material in the fiber 220. In some examples, the melting point of the polyamide or copolyamide in fibers 210 may be at least 40 degrees higher than the melting point of the material in fibers 220. In other examples, the melting point of the polyamide or copolyamide in fibers 210 may be at least 45 degrees higher than the melting point of the material in fibers 220. In additional examples, the melting point of the polyamide or copolyamide in fibers 210 may be at least 50 degrees higher than the melting point of the material in fibers 220.

[0046] In certain examples, the fiber 220 may include polyethylene, such as LLDPE, and the fiber 210 may include polyester or polyamide. For example, the fiber 210 may include nylon, polyethylene terephthalate, polybutylene terephthalate, polynaphthalene terephthalate, or combinations thereof. In certain examples, the melting point of the polyester or polyamide in the fiber 210 may be at least 15 degrees higher than the melting point of the polyethylene material in the fiber 220. In some examples, the melting point of the polyester or polyamide in the core fiber 210 may be at least 20 degrees higher than the melting point of the polyethylene material in the fiber 220. In certain examples, the melting point of the polyester or polyamide in the fiber 210 may be at least 25 degrees higher than the melting point of the polyethylene material in the fiber 220. In other examples, the melting point of the polyester or polyamide in the fiber 210 may be at least 30 degrees higher than the melting point of the polyethylene material in the fiber 220. In certain examples, the melting point of the polyester or polyamide in the fiber 210 may be at least 35 degrees higher than the melting point of the polyethylene material in the fiber 220. In some examples, the melting point of the polyester or polyamide in fibers 210 may be at least 40 degrees higher than the melting point of the polyethylene material in fibers 220. In other examples, the melting point of the polyester or polyamide in fibers 210 may be at least 45 degrees higher than the melting point of the polyethylene material in fibers 220. In additional examples, the melting point of the polyester or polyamide in fibers 210 may be at least 50 degrees higher than the melting point of the polyethylene material in fibers 220.

[0047] Referring to Figure 3A, an illustration showing a cross section through a parallel fiber arrangement of bicomponent fibers with a shell surrounding the parallel fiber arrangement is shown. For example, fiber 300 includes a shell 320 surrounding two fibers 310, 315. In Figure 3A, fibers 310, 315 can include the same or similar composition. For example, each of fibers 310, 315 can independently include the same material as described in connection with core material 110 of Figure 1, e.g., each of fibers 310, 315 can independently include polyamide, polyester, or other polymer.

[0048] In certain embodiments, the shell material 320 may include a polyolefin. In some examples, the polyolefin of the shell material 320 may be polyethylene, polypropylene, or other olefin-based polymers and copolymers. In some embodiments, the polyolefin material of the shell 320 may be considered a linear low density polyolefin. For example, the polyolefin material of the shell 320 may be linear low density polyethylene (LLDPE) or low density polyethylene (LDPE). While the exact material properties may vary, linear low density polyethylene has a viscosity of approximately 0.91 g / cm 3 ~Approx. 0.94g / cm 3 In some examples, the melting point of the LLDPE or LDPE may be at least 15 degrees Celsius lower than the melting point of the fibers 310, 315. In certain examples, the melting point of the LLDPE or LDPE may be at least 20 degrees Celsius lower than the melting point of the fibers 310, 315. In other examples, the melting point of the LLDPE or LDPE may be at least 25 degrees Celsius lower than the melting point of the fibers 310, 315. In certain examples, the melting point of the LLDPE or LDPE may be at least 30 degrees Celsius lower than the melting point of the fibers 310, 315. In other examples, the melting point of the LLDPE or LDPE may be at least 35 degrees Celsius lower than the melting point of the fibers 310, 315. In certain examples, the melting point of the LLDPE or LDPE may be at least 40 degrees Celsius lower than the melting point of the fibers 310, 315. In other examples, the melting point of the LLDPE or LDPE may be at least 45 degrees Celsius lower than the melting point of the fibers 310, 315. In some examples, the melting point of the LLDPE or LDPE may be at least 50 degrees Celsius lower than the melting point of the fibers 310, 315.

[0049] In certain examples, the fibers 310, 315 may independently comprise polyester or polyamide. In some cases, the fibers 310, 315 may independently comprise nylon, polyethylene terephthalate, polybutylene terephthalate, polynaphthalene terephthalate, or combinations thereof. In certain examples, the melting point of the polyester or polyamide in the fibers 310, 315 may be at least 15 degrees higher than the melting point of the polyethylene material in the shell material 320. In some examples, the melting point of the polyester or polyamide in the fibers 310, 315 may be at least 20 degrees higher than the melting point of the polyethylene material in the shell material 320. In certain examples, the melting point of the polyester or polyamide in the fibers 310, 315 may be at least 25 degrees higher than the melting point of the polyethylene material in the shell material 320. In other examples, the melting point of the polyester or polyamide in the fibers 310, 315 may be at least 30 degrees higher than the melting point of the polyethylene material in the shell material 320. In certain examples, the melting point of the polyester or polyamide in the fibers 310, 315 may be at least 35 degrees higher than the melting point of the polyethylene material in the shell material 320. In some examples, the melting point of the polyester or polyamide in the fibers 310, 315 may be at least 40 degrees higher than the melting point of the polyethylene material in the shell material 320. In other examples, the melting point of the polyester or polyamide in the fibers 310, 315 may be at least 45 degrees higher than the melting point of the polyethylene material in the shell material 320. In additional examples, the melting point of the polyester or polyamide in the fibers 310, 315 may be at least 50 degrees higher than the melting point of the polyethylene material in the shell material 320.

[0050] FIG. 3A shows two parallel fibers that may have the same composition, but this configuration is not required. For example, referring to FIG. 3B, a parallel arrangement of fibers 360, 365 surrounded by a shell 370 is shown. The fibers 360, 365 do not have to have the same composition as each other, but the melting point of each of the fibers 360, 365 is typically higher than the melting point of the shell 370 in the fiber arrangement 350. In one configuration, one of the fibers 360, 365 is an inorganic fiber, such as a reinforcing fiber, as described below, e.g., glass fiber, graphite fiber, carbon fiber, etc., and the other of the fibers 360, 365 is an organic fiber, e.g., containing one or more covalently bonded carbon-hydrogen groups. Packaging the inorganic and organic fibers in a shell may simplify the addition of fibers during processing of the material to form the core layer. In another example, the fibers 360, 365 may each be an organic fiber having a different composition.

[0051] In certain embodiments, the shell material 370 may include a polyolefin. In some examples, the polyolefin of the shell material 370 may be polyethylene, polypropylene, or other olefin-based polymers and copolymers. In some embodiments, the polyolefin material of the shell 370 may be considered a linear low density polyolefin. For example, the polyolefin material of the shell 370 may be linear low density polyethylene (LLDPE) or low density polyethylene (LDPE). While the exact material properties may vary, linear low density polyethylene has a viscosity of approximately 0.91 g / cm 3 ~Approx. 0.94g / cm 3In some examples, the melting point of the LLDPE or LDPE may be at least 15 degrees Celsius lower than the melting point of the fibers 360, 365. In certain examples, the melting point of the LLDPE or LDPE may be at least 20 degrees Celsius lower than the melting point of the fibers 360, 365. In other examples, the melting point of the LLDPE or LDPE may be at least 25 degrees Celsius lower than the melting point of the fibers 360, 365. In certain examples, the melting point of the LLDPE or LDPE may be at least 30 degrees Celsius lower than the melting point of the fibers 360, 365. In other examples, the melting point of the LLDPE or LDPE may be at least 35 degrees Celsius lower than the melting point of the fibers 360, 365. In certain examples, the melting point of the LLDPE or LDPE may be at least 40 degrees Celsius lower than the melting point of the fibers 360, 365. In other examples, the melting point of the LLDPE or LDPE may be at least 45 degrees Celsius lower than the melting point of the fibers 360, 365. In some instances, the melting point of the LLDPE or LDPE may be at least 50 degrees Celsius lower than the melting point of the fibers 360, 365.

[0052] In certain examples, the fibers 360, 365 may independently comprise polyester or polyamide, or one of the fibers 360, 365 may be an inorganic reinforcing fiber. In some cases, the fibers 360, 365 may independently comprise nylon, polyethylene terephthalate, polybutylene terephthalate, polynaphthalene terephthalate, or combinations thereof. In certain examples, the melting point of the material in the fibers 360, 365 may be at least 15 degrees higher than the melting point of the polyethylene material in the shell material 370. In some examples, the melting point of the material in the fibers 360, 365 may be at least 20 degrees higher than the melting point of the polyethylene material in the shell material 370. In certain examples, the melting point of the material in the fibers 360, 365 may be at least 25 degrees higher than the melting point of the polyethylene material in the shell material 370. In other examples, the melting point of the material in the fibers 360, 365 may be at least 30 degrees higher than the melting point of the polyethylene material in the shell material 370. In certain examples, the melting point of the material in the fibers 360, 365 may be at least 35 degrees higher than the melting point of the polyethylene material in the shell material 320. In some examples, the melting point of the material in the fibers 360, 365 may be at least 40 degrees higher than the melting point of the polyethylene material in the shell material 370. In other examples, the melting point of the material in the fibers 360, 365 may be at least 45 degrees higher than the melting point of the polyethylene material in the shell material 370. In additional examples, the melting point of the material in the fibers 360, 365 may be at least 50 degrees higher than the melting point of the polyethylene material in the shell material 370.

[0053] In a particular embodiment, referring to FIG. 4, a core layer 410 is shown that includes a thermoplastic material, reinforcing fibers, bicomponent fibers, and a lofting agent. Although not true for all configurations, the lofting agent is typically trapped within the voids or pores of the core layer 410. The core layer 410 may first be formed as a prepreg, which is generally a precursor to the core layer 410 and is not necessarily fully formed. For ease of illustration, the core layer is described below, but the properties of the core layer may also be the same as the prepreg. The core layer 410 includes a porous structure that allows gas to flow through the core layer. For example, the core layer can be set to 0-30%, 10-40%, 20-50%, 30-60%, 40-70%, 50-80%, 60-90%, 0-40%, 0-50%, 0-60%, 0-70%, 0-80%, 0-90%, 10-50%, 10-60%, 10-70%, 10-80%, 10-90%, 10-95%, 20-60%, 20-70%, 20-80%, 20-95%, 20-10%, 20-15%, 20-25%, 20-30%, 20-40%, 20-50%, 20-60%, 20-70%, 20-80%, 20-95%, 20-15%. The core layer 410 may include a void content or porosity of 0%, 20% to 95%, 30% to 70%, 30% to 80%, 30% to 90%, 30% to 95%, 40% to 80%, 40% to 90%, 40% to 95%, 50% to 90%, 50% to 95%, 60% to 95%, 70% to 80%, 70% to 90%, 70% to 95%, 80% to 90%, 80% to 95%, or any exemplary value within these exemplary ranges. In some cases, the core layer 410 includes a porosity or void content of greater than 0%, e.g., up to about 95% that is not fully consolidated. Unless otherwise indicated, references to a core layer including a particular void content or porosity are based on the total volume of the core layer, and not necessarily the total volume of the core layer plus any other materials or layers bonded to the core layer.

[0054] In certain embodiments, the thermoplastic material of the core layer 410 may at least partially comprise one or more of polyethylene, polypropylene, polystyrene, acrylonitrile styrene, butadiene, polyethylene terephthalate, polybutylene terephthalate, polybutylene tetrachlorate, and polyvinyl chloride, both plasticized and unplasticized, as well as blends of these materials with each other or with other polymeric materials. Other suitable thermoplastics include, but are not limited to, polyarylene ethers, polycarbonates, polyester carbonates, thermoplastic polyesters, polyimides, polyetherimides, polyamides, acrylonitrile-butyl acrylate-styrene polymers, amorphous nylons, polyarylene ether ketones, polyphenylene sulfides, polyarylsulfones, polyethersulfones, liquid crystal polymers, poly(1,4 phenylene) compounds commercially known as PARMAX®, high heat polycarbonates such as Bayer's APEC® PC, high temperature nylons, and silicones, as well as alloys and blends of these materials with each other or with other polymeric materials. The virgin thermoplastic material used to form the core layer may be used in powder form, resin form, rosin form, fiber form, or other suitable form. Various forms of exemplary thermoplastic materials are described herein, but are also described, for example, in U.S. Patent Application Publication Nos. 2013 / 0244528 and 2012 / 0065283. The exact amount of thermoplastic material present in the core layer 410 may vary, with exemplary amounts ranging from about 20% to about 80% by weight. As described herein, the material of the core layer 410 may be selected such that its melting point is approximately the same as one of the materials in the bicomponent fiber and less than the melting point of another material in the bicomponent fiber. Exemplary melting point ranges for the thermoplastic material include, but are not limited to, about 120 degrees Celsius to about 260 degrees Celsius. Thermoplastic materials that melt between 100 degrees Celsius and 315 degrees Celsius may also be used if desired.

[0055] In certain examples, the reinforcing fibers of the core layer described herein can include glass fibers, carbon fibers, graphite fibers, synthetic organic fibers, such as para-aramid and meta-aramid fibers, nylon fibers, polyester fibers, or organic fibers with particularly high modulus, such as any high melt flow index resin suitable for use as fibers, natural fibers, such as hemp, sisal, jute, flax, coir, kenaf, and cellulosic fibers, mineral fibers, such as basalt, mineral wool (e.g., rock wool or slag wool), wollastonite, alumina silica, and the like, or mixtures thereof, metal fibers, metallized natural and / or synthetic fibers, ceramic fibers, yarn fibers, or mixtures thereof. In some cases, one type of reinforcing fiber can be used with mineral fibers, such as fibers formed by spinning or drawing molten minerals. Exemplary mineral fibers include, but are not limited to, mineral wool fibers, glass wool fibers, stone wool fibers, and ceramic wool fibers. In some examples, the reinforcing fibers can be selected to be inorganic fibers, such as fibers that do not contain covalently bonded carbon-hydrogen groups.

[0056] In some embodiments, any of the aforementioned reinforcing fibers may be chemically treated prior to use to provide the fibers with desired functional groups or to impart other physical properties. The total fiber content in the core layer (reinforcing fibers + bicomponent fibers) may be about 20% to about 90% by weight of the core layer, more specifically, about 30% to about 70% by weight of the core layer. Typically, the total fiber content of a composite article including a core layer varies from about 20% to about 90% by weight of the composite, more specifically, about 30% to about 80% by weight, e.g., about 40% to about 70% by weight. The specific size and / or orientation of the reinforcing fibers used may depend, at least in part, on the polymeric material used and / or the desired properties of the resulting core layer. Suitable additional fiber types, fiber sizes, and amounts will be readily selected by one of ordinary skill in the art given the benefit of this disclosure. In a non-limiting illustration, the reinforcing fibers dispersed in the thermoplastic material to provide the core layer generally have a diameter greater than about 5 micrometers, more specifically, between about 5 micrometers and about 22 micrometers, and a length between about 5 mm and about 200 mm. More specifically, the diameter of the reinforcing fibers can be between about 5 micrometers and about 22 micrometers, and the length of the fibers can be between about 5 mm and about 75 mm. In some configurations, the flame retardant material can be present in fibrous form. For example, the core layer can include a thermoplastic material, a reinforcing fiber, a bicomponent fiber, and a fiber including a flame retardant material.

[0057] In some configurations, the core layer 410 may be a substantially halogen-free or halogen-free layer to meet regulations regarding hazardous material requirements for certain applications. In other cases, the core layer 410 may include halogenated flame retardants (which may be present in the flame retardant material or may be additionally added to the flame retardant material), such as halogenated flame retardants including one or more of F, Cl, Br, I, and At, or compounds containing such halogens, such as tetrabromobisphenol-A polycarbonate, or monohalo-, dihalo-, trihalo-, or tetrahalo-polycarbonates. In some cases, the thermoplastic material used in the core layer 410 may include one or more halogens to impart some degree of flame retardancy without the addition of a separate flame retardant. For example, the thermoplastic material may be halogenated in addition to the flame retardant material being present, or virgin thermoplastic material may be halogenated and used on its own. If a halogenated flame retardant is present, it is desirably present in an amount of flame retardant that may vary depending on other components present. For example, the halogenated flame retardant present in addition to the flame retardant material may be present at about 0.1 weight percent to about 40 weight percent (based on the weight of the prepreg), more specifically, about 0.1 weight percent to about 15 weight percent, such as about 5 weight percent to about 15 weight percent. If desired, two different halogenated flame retardants may be added to the core layer 410. In other cases, a non-halogenated flame retardant may be added, such as a flame retardant containing one or more of N, P, As, Sb, Bi, S, Se, and Te. In some embodiments, the non-halogenated flame retardant may include a phosphorus-containing material, so that the core layer 410 may be more environmentally friendly. When a non-halogenated or substantially halogen-free flame retardant is present, the flame retardant is desirably present in an amount of the flame retardant that may vary depending on other components present. For example, the substantially halogen-free flame retardant can be present from about 0.1 weight percent to about 40 weight percent (based on the weight of the prepreg), more specifically, from about 5 weight percent to about 40 weight percent, such as from about 5 weight percent to about 15 weight percent, based on the weight of the core layer.If desired, two different substantially halogen-free flame retardants may be added to the core layer 410. In certain cases, the core layer 410 described herein may include one or more halogenated flame retardants in combination with one or more substantially halogen-free flame retardants. When two different flame retardants are present, the combination of the two flame retardants may be present in an amount of flame retardant that may vary depending on the other components present. For example, the total weight of the flame retardants present may be from about 0.1 weight percent to about 40 weight percent (based on the weight of the prepreg or core), more specifically, from about 5 weight percent to about 40 weight percent, e.g., from about 2 weight percent to about 14 weight percent, based on the weight of the core layer. The flame retardants used in the core layer described herein may be added to the mixture including the thermoplastic material, bicomponent fiber, and reinforcing fiber (prior to placement of the mixture on a wire screen or other processing component) or may be added after the core layer 410 is formed.

[0058] As described herein, the core layer 410 may include a lofting agent present in the pores or voids of the core layer. The lofting agent may take the form of expandable microspheres that may increase in volume upon exposure to heat or other stimuli. For example, the thickness of the core layer 410 may be increased by expanding the lofting agent. The exact amount of lofting agent present in the core layer 410 may vary, with exemplary amounts including, but not limited to, about 0.5 weight percent to about 15 weight percent.

[0059] In certain embodiments, the exact amount of bicomponent fiber in the core layer described herein may vary. Generally, the weight percent of bicomponent fiber in the core layer may vary from about 2 weight percent to about 30 weight percent. In some examples, approximately equal amounts of bicomponent fiber and reinforcing fiber are present in the core layer.

[0060] In certain embodiments, the core layer and / or articles described herein can be prepared using reinforcing fibers, bicomponent fibers, lofting agents, and thermoplastic materials, generally as shown in FIG. 5. To produce the core layer, the thermoplastic materials, reinforcing fibers, bicomponent fibers, lofting agents, and optionally other materials can be added or metered in step 510 to a dispersed foam contained in an open-top mixing tank fitted with an impeller to provide an aqueous dispersion of the materials. Without wishing to be bound by any particular theory, the presence of trapped air pockets in the foam can aid in the dispersion of the reinforcing fibers, bicomponent fibers, thermoplastic materials, lofting agents, and any other materials. In some examples, the dispersed mixture of fibers, lofting agents, and thermoplastic materials can be pumped through a dispersion manifold to a headbox positioned above the wire section of a papermaking machine. For example, the aqueous mixture can be deposited in step 520 on a moving wire screen or other support element. The dispersed mixture can then be applied to a moving support, such as a wire screen, using pressure to continuously produce a uniform, fibrous wet-laid web with the lofting agent trapped in the web, while the foam, but not the fibers, lofting agent, or thermoplastic material, can be removed. The wet-laid web can be passed through a dryer at a suitable temperature to reduce the moisture content and melt or soften at least one of the thermoplastic and bicomponent fibers to provide a core layer in step 530. As the hot web exits the dryer, an optional surface or skin layer, such as, for example, a textured film, can be laminated onto the web by passing the web of reinforcing fibers, bicomponent fibers, thermoplastic material, lofting agent, and textured film through the nip of a set of heated rollers. If desired, additional layers, such as, for example, another film layer, a scrim layer, can also be attached to one or both sides of the web with the textured film to facilitate handling of the resulting composite. The composite can then be passed through a tension roll and continuously cut (cut) to a desired size for later formation into a final composite article.Further information regarding the preparation of such complexes, including suitable materials and processing conditions used to form such complexes, is described, for example, in U.S. Pat. Nos. 6,923,494, 4,978,489, 4,944,843, 4,964,935, 4,734,321, 5,053,449, 4,925,615, 5,609,966, and U.S. Patent Application Publication Nos. US2005 / 0082881, US2005 / 0228108, US2005 / 0217932, US2005 / 0215698, US2005 / 0164023, and US2005 / 0161865.

[0061] In another configuration, the core layer and / or articles described herein can be prepared using reinforcing fibers, bicomponent fibers, and thermoplastic materials, generally as shown in FIG. 6. To produce the core layer, the thermoplastic materials, reinforcing fibers, bicomponent fibers, and optionally other materials can be added or metered in step 610 to a dispersed foam contained in an open-top mixing tank fitted with an impeller to provide an aqueous dispersion. Without wishing to be bound by any particular theory, the presence of trapped air pockets in the foam can aid in the dispersion of the reinforcing fibers, bicomponent fibers, thermoplastic materials, and any other materials. In some examples, the dispersed mixture of fibers and thermoplastic materials can be pumped through a dispersion manifold to a headbox positioned above the wire section of a papermaking machine. For example, the aqueous mixture can be deposited in step 620 on a moving wire screen or other support element to provide a wet web. The foam, but not the fibers or thermoplastic materials, can then be removed as the dispersed mixture is provided to a moving support, such as a wire screen, using pressure to continuously produce a uniform fibrous wet web. The lofting agent can then be deposited or sprayed on top of the wet web in step 625 to provide a wet web containing the lofting agent. The wet web containing the deposited lofting agent can be passed through a dryer, optionally under vacuum or by applying pressure and heat at a suitable temperature to reduce the moisture content and melt or soften at least one of the thermoplastic material and the bicomponent fiber to provide a core layer in step 630. As the hot web exits the dryer, an optional surface or skin layer, such as, for example, a textured film, can be laminated onto the web by passing the web of reinforcing fibers, bicomponent fibers, thermoplastic material, lofting agent, and textured film through the nip of a set of heated rollers. If desired, additional layers, such as, for example, another film layer, a scrim layer, can also be attached to one or both sides of the web with the textured film to facilitate handling of the resulting composite.The composite may then be passed through tension rolls and subsequently cut (cut) to the desired size for later formation into the final composite article.

[0062] In certain embodiments, the core layer described herein can be used with a skin layer to provide a composite article. With reference to FIG. 7, a skin layer 720 is shown disposed on a first surface of the core layer 410 to provide a composite article 700. The skin layer 720 can include, for example, a film, a scrim (e.g., a fiber-based scrim), a frim (film + scrim), a foil, a woven fabric, a nonwoven fabric, or can be present as an inorganic coating, an organic coating, or a thermosetting coating disposed on the core layer. In other cases, the layer 720 can include a limiting oxygen index greater than about 22 as measured by ISO 4589, 1996. When a fiber-based scrim is present as (or as part of) the skin layer 720, the fiber-based scrim can include at least one of glass fibers, aramid fibers, graphite fibers, carbon fibers, inorganic mineral fibers, metal fibers, metallized synthetic fibers, and metallized inorganic fibers. If a thermosetting coating is present as (or as part of) layer 720, the coating may include at least one of unsaturated polyurethane, vinyl ester, phenolic, and epoxy. If an inorganic coating is present as (or as part of) layer 720, the inorganic coating may include a mineral containing a cation selected from Ca, Mg, Ba, Si, Zn, Ti, and Al, or may include at least one of gypsum, calcium carbonate, and mortar. If a nonwoven fabric is present as (or as part of) layer 720, the nonwoven fabric may include a thermoplastic material, a thermosetting binder, inorganic fibers, metal fibers, metallized inorganic fibers, and metallized synthetic fibers. If desired, an intermediate layer (not shown) may be present between the core layer and the skin layer 720. For example, an adhesive layer or other layer of material may be present between the core layer 410 and the skin layer 720.

[0063] In some examples, the composite article may also include a second skin layer disposed on another surface of the core layer. With reference to FIG. 8, a composite article 800 is shown including skin layers 720, 820 sandwiching the core layer 410. Layer 820 may be the same as or different from layer 720. In some cases, layer 820 may include, for example, a film, a scrim (e.g., fiber-based scrim), a flim (film + scrim), a foil, a woven fabric, a nonwoven fabric, or may be present as an inorganic coating, an organic coating, or a thermoset coating disposed on the core layer. In other cases, layer 820 may include a limiting oxygen index greater than about 22 as measured by ISO 4589, 1996. When a fiber-based scrim is present as (or as part of) layer 820, the fiber-based scrim may include at least one of glass fibers, aramid fibers, graphite fibers, carbon fibers, inorganic mineral fibers, metal fibers, metallized synthetic fibers, and metallized inorganic fibers. If a thermosetting coating is present as (or as part of) layer 820, the coating may include at least one of unsaturated polyurethane, vinyl ester, phenolic, and epoxy. If an inorganic coating is present as (or as part of) layer 820, the inorganic coating may include a mineral containing a cation selected from Ca, Mg, Ba, Si, Zn, Ti, and Al, or may include at least one of gypsum, calcium carbonate, and mortar. If a nonwoven fabric is present as (or as part of) layer 820, the nonwoven fabric may include a thermoplastic material, a thermosetting binder, inorganic fibers, metal fibers, metallized inorganic fibers, and metallized synthetic fibers. If desired, an intermediate layer (not shown) may be present between the core layer and the skin layer 820. For example, an adhesive layer or other layer of material may be present between the core layer 410 and the skin layer 820.

[0064] In certain configurations, the composite article can include a decorative layer disposed on a surface of the core layer or on a skin layer. With reference to FIG. 9, an article 900 is shown including a decorative layer 830 disposed on a skin layer 720. Although not shown, the decorative layer can be disposed on the opposite surface of the core layer 410 or on the skin layer 820 shown in FIG. 8. In some examples, the decorative layer 930 can be configured as a decorative layer, a texturing layer, a coloring layer, or the like. For example, the decorative layer 930 can be formed from a thermoplastic film, such as, for example, polyvinyl chloride, polyolefin, thermoplastic polyester, thermoplastic elastomer, or the like. The decorative layer 930 can also be a multi-layer structure including a foam core formed from, for example, polypropylene, polyethylene, polyvinyl chloride, polyurethane, or the like. Fabrics can be bonded to the foam core, such as natural and synthetic fibers, organic fiber nonwovens after needle punching or the like, brushed fabrics, knit goods, flock fabrics, or woven fabrics made from other such materials. Fabrics can also be bonded to the foam core with thermoplastic adhesives, including pressure sensitive adhesives and hot melt adhesives such as polyamides, modified polyolefins, urethanes, and polyolefins. The decorative layer 930 may also be produced using spunbond, thermal bond, spunlace, meltblown, wet laid processes, and / or dry laid processes. Insulating or acoustical layers may also be bonded to one or more surfaces of the articles described herein, and the insulating or acoustical layers may be, for example, open cell or closed cell foams, open-ended or closed, as desired.

[0065] In certain embodiments, the core layers and articles described herein can be used in architectural and automotive applications, such as, for example, headliners, rear window trim, trunk trim, office partition panels, cabinet back panels, automotive interior panels, or other automotive interior articles.

[0066] To further illustrate some of the aspects of the technology described herein, certain specific examples are described.

[0067] Example 1 Some articles were tested for their free loft ability. Free loft can be used as a measure of the retention of a lofting agent. Free loft was measured by punching disks from the sheet article. The punched disks were heated in an oven at about 200 degrees Celsius to loft the punched disks. After heating for about 5 minutes, the lofted disks were removed and allowed to cool on a flat surface for about 1 minute. The thickness of the lofted disks was then measured.

[0068] Each of the samples tested has a total areal density of 1000 gsm. Table 1 below shows the materials and their amounts used to produce each sample. The difference in free loft in the absence (sample HS1) and presence (HS2) of bicomponent fiber is also shown. The bicomponent fiber used was a core-shell fiber with the shell comprising LLDPE and the core comprising polyethylene terephthalate. [Table 1]

[0069] The free loft was increased by over 20% in the presence of the polymeric bicomponent fiber, even though the same amount of loft agent was used to generate both samples. These results are consistent with the bicomponent fiber providing enhanced retention of the loft agent, thereby providing increased free loft capacity.

[0070] When introducing elements of the embodiments disclosed herein, the articles "a," "an," "the," and "said" are intended to mean that there is one or more elements. The terms "comprising," "including," and "having" are intended to be open-ended and mean that there may be additional elements other than the listed elements. Those skilled in the art will recognize, given the benefit of this disclosure, that various components of the embodiments may be interchanged or substituted for various components in other embodiments.

[0071] While particular aspects, examples, and embodiments have been described above, those of ordinary skill in the art, given the benefit of this disclosure, will recognize that additions, substitutions, modifications, and variations of the disclosed exemplary aspects, configurations, examples, and embodiments are possible.

Claims

1. 1. A method of producing a porous composite article, comprising: combining in a liquid inorganic reinforcing fibers, organic reinforcing fibers, a loft agent comprising expandable microspheres, and a thermoplastic material to produce an aqueous foam, wherein the organic reinforcing fibers comprise a core-shell configuration, a shell material in the shell of the core-shell configuration comprises a polyolefin, and a core material in the core of the core-shell configuration comprises a melting point at least 20 degrees Celsius higher than a melting point of the polyolefin of the shell material; depositing the aqueous foam onto a moving wire screen; removing liquid from the deposited aqueous foam on the moving wire screen to form an open-celled web formed from the thermoplastic material, the inorganic reinforcing fibers, the organic reinforcing fibers, and the loft agent; and compressing the formed web to provide the porous composite article.

2. The method of claim 1 , wherein negative pressure is provided to a bottom surface of the formed web during deposition of the lofting agent to draw the lofting agent into voids in the formed web.

3. The method of claim 1 , wherein the core material of the organic reinforcing fibers comprises polyester.

4. The method of claim 1 , wherein the polyolefin of the shell material comprises polyethylene.

5. The method of claim 4, wherein the polyethylene is a linear low density polyethylene.

6. The density of the linear low density polyethylene is 0.91 g / cm 3 ~0.94g / cm 3 The method according to claim 5, wherein

7. The method of claim 3 , wherein the polyester comprises one or more of polyethylene terephthalate, polybutylene terephthalate, and polynaphthalene terephthalate.

8. The method of claim 1 , wherein the core material of the organic reinforcing fibers comprises a polyamide.

9. The method of claim 8 , wherein the polyolefin comprises polyethylene.

10. 10. The method of claim 9, wherein the polyethylene is a linear low density polyethylene.

11. The density of the linear low density polyethylene is 0.91 g / cm 3 ~0.94g / cm 3 The method of claim 10, wherein

12. The method of claim 8 , wherein the polyamide comprises a copolyamide.

13. The method of claim 8 , wherein the polyamide comprises nylon.

14. The method of claim 1 , wherein the thermoplastic material comprises a polyolefin, the inorganic reinforcing fibers comprise glass fibers, and the core material of the organic reinforcing fibers comprises a polyester.

15. 15. The method of claim 14, wherein the thermoplastic material is polypropylene, the polyolefin of the shell material comprises polyethylene, and the polyester of the core material comprises polyethylene terephthalate.

16. The method of claim 1 , wherein the thermoplastic material comprises a polyolefin, the inorganic reinforcing fibers comprise glass fibers, and the core material of the organic reinforcing fibers comprises a polyamide.

17. 17. The method of claim 16, wherein the thermoplastic material is polypropylene, the polyolefin of the shell material comprises polyethylene, and the polyamide of the core material comprises nylon.

18. 2. The method of claim 1, wherein the thermoplastic material comprises polypropylene, the inorganic reinforcing fibers comprise glass fibers, the core material of the organic reinforcing fibers comprises polyester, and the shell material of the organic reinforcing fibers comprises polyethylene, the melting point of the polyester in the core material is at least 50 degrees Celsius higher than the melting point of the polyethylene in the shell material, and the porous thermoplastic composite article comprises a porosity of 20% to 80%.

19. 2. The method of claim 1, wherein the thermoplastic material comprises polypropylene, the inorganic reinforcing fibers comprise glass fibers, the core material of the organic reinforcing fibers comprises polyamide, and the shell material of the organic reinforcing fibers comprises polyethylene, the melting point of the polyamide in the core material is at least 50 degrees Celsius higher than the melting point of the polyethylene in the shell material, and the porous thermoplastic composite article comprises a porosity of 20% to 80%.

Images