BALANCED FINE CORESPUN YARN

CROSS REFERENCE TO PRIOR APPLICATIONS

[0001] This application claims priority and the benefit thereof from a U.S. Provisional Application No. 61/326,077, filed on April 20, 2010 and entitled DIRECT APPLICATION OF FOAM TO FIRE RESISTANT FABRIC MADE OF BALANCED FINE CORESPUN YARN, the entire contents of which are herein incorporated by reference in their entirety.

FIELD OF THE INVENTION

[0002] The invention relates to a fire resistant fabric coated with foam, and more specifically at least one layer of latex foam coating a fine textured fire resistant flame barrier lightweight fabric substrate. The invention also discloses a process for applying the at least one layer of foam to the fine textured fire resistant flame barrier lightweight fabric substrate.

BACKGROUND OF THE INVENTION

[0003] The United States mattress industry is constantly striving to improve mattress comfort, while complying with 16 Code of Federal Regulations Part 1633, the United States standards for the flammability of mattress sets and improving profitability by reducing manufacturing costs or increasing value added features.

[0004] The choice of a fire resistant flame barrier fabric used to make mattress coverings, mattress pads, mattress covers, and other upholstered components depend on the barrier's effect on the feel and comfort of the finished product, as well as on its cost. A flame barrier fabric that is too thick or too elastic may impose a nuisance layer between the consumer and the feel of the finished article. [0005] Latex, particularly foam latex, is a more and more common material for use in mattresses due to its soft, lightweight and flexible nature. However, mattress construction that incorporates latex are among the most difficult to bring into compliance with federal flammability regulations.

[0006] There is a need to meet United States federal flammability regulations for mattresses which incorporate latex, in a cost effective manner, while providing a supplemental layer of fire protection in mattress construction and enhance the consumer's comfort while using the mattress.

SUMMARY OF THE INVENTION

[0007] The invention, as described below discloses the direct application of foam, with at least one latex foam layer, to a fire resistant flame barrier fabric formed from balanced fine corespun yarn having a high temperature resistant fiberglass core and a low temperature resistant staple fiber sheath, treated with durable or non-durable fire retardant agents, surrounding the fiberglass core.

[0008] United States mattress manufacturers are required to meet federal flammability regulations for mattresses sold in the U.S. Among the most difficult products to bring into compliance are the mattresses which incorporate latex. This invention may include aspects of U.S Patent 5,540,980 for fire resistant fabric made of balanced, fine corespun yarn incorporated herein by reference in its entirety. The invention may also include aspects of U.S. Published Patent Application 2009/0176076 Al which teaches the application of multiple layer foams on generic substrates incorporated herein by reference in its entirety. This invention discloses a unitized layer of latex foam, with at least one layer of latex, with the fire barrier substrate fabric of corespun yarn, and a method for producing the same. [0009] The invention may be implemented in a number of ways. According to one aspect of the invention a fire resistant fabric coated with foam including a fine textured fire resistant flame barrier lightweight fabric substrate formed of a nonlively nonplied fine balanced corespun yarn including the yarn being air jet spun without any appreciable twist and including a core of high temperature resistant continuous filament fiberglass constituting about 20% to 40% of total weight of the corespun yarn, a sheath of low temperature resistant staple fibers surrounding and covering said core constituting about 80%> to 60%> of the total weight of said corespun yarn, and a foam coating substantially completely covering and adhering to at least one side of said fabric.

[0010] The sheath of the corespun yarn may include blends of natural and or unnaturally occurring fibers comprising at least one of: animal, vegetable, mineral, wool, cotton, polyester, modacrylic, nylon, rayon, Lyocell, Kenaf, Hemp, Jute, acetate, and blends thereof. The yarn may be one of knit or woven.

[0011] The foam may include multiple layers of foam comprising at least one layer of latex foam. The latex foam material may include at least one of: natural rubber, polybutadiene/styrene, polybutadiene/acrylonitrile, polychloroprene, other synthetic latexes, and a mixture of natural rubber and one ore more synthetic latexes. The foam may include multiple layers of different alternating conventional or visco-elastic latex foam and at least one of: polyolefin, polyurethane, polystyrene, polyester, and mixtures thereof.

[0012] The first layer of multilayer foam may be a higher thickness, weight, and or density than subsequent foam layers. The total number of layers may be at least three. The foam may be one of vulcanized and cured to conform to the fire resistant fabric. The first layer of foam may be vulcanized prior to the pouring of foam material for a second layer of foam on top of the first layer. The vulcanization or curing may render the foam stable for use in mattress and upholstery applications. [0013] According to another aspect of the invention a process for manufacturing a foam covered fire resistant fabric substrate formed of corespun yarn may include at least one of: producing a fine textured fire resistant flame barrier lightweight fabric substrate formed of a nonlively nonplied fine balanced corespun yarn including a core of high temperature resistant continuous filament fiberglass constituting about 20% to 40% of the total weight of the corespun yarn, and a sheath of low temperature resistant staple fibers surrounding and covering said core constituting about 80%> to 60%> of the total weight of the corespun yarn, injecting or pouring a first layer of latex foam of pre-determined thickness onto a fire resistant fabric substrate and vulcanizing at the first layer of latex in order to conform the substrate for use in a mattress or as upholstery.

[0014] The process may further include injecting or pouring another layer of foam of pre-determined thickness onto the previous layer and vulcanizing the layer. The process may further include at least one of washing and drying the fire resistant fabric substrate with foam prior to conforming it for use in a mattress or as upholstery. The foam treated fabric may also cured in addition or in lieu of the vulcanization process.

[0015] The foam and fire resistant fabric substrate may move along a conveyor belt from one station to the next in a continuous process. The speed of the continuous conveying mechanism may be between 0.25 and 2.5 m/min.

[0016] The invention involves the direct application of single or multiple layer foams directly on a fire resistant flame durable balanced or nonlively fine corespun yarn substrate and other fire-retardant yarns for use as a mattress and upholstery. This creates a unitized layer of foam with a barrier layer which would save on labor costs and materials costs by eliminating the barrier application. [0017] In addition, the foam/barrier composite layer may function as an added layer of fire protection for the mattress, and may also serve as the primary barrier for the mattresses' top surface. This invention incorporations a robust flame barrier into the foam itself that includes a structural component of the mattress. This is an improvement over the laying of a fire resistant fabric over or around a foam layer without unitizing the two layers together. Another advantage of this invention over previous inventions is the enhanced comfort of the foam mattress. Additional advantages are evident from the description.

[0018] Additional features, advantages, and embodiments of the invention may be set forth or apparent from consideration of the detailed description and drawings. Moreover, it is to be understood that both the foregoing summary of the invention and the following detailed description are exemplary and intended to provide further explanation without limiting the scope of the invention as claimed.

DETAILED DESCRIPTION OF THE INVENTION

[0019] The embodiments of the invention and the various features and advantageous details thereof are explained more fully with reference to the non-limiting embodiments and examples that are detailed in the following attached description. It should be noted that the features of one embodiment may be employed with other embodiments as the skilled artisan would recognize, even if not explicitly stated herein. Descriptions of well-known components and processing techniques may be omitted so as to not unnecessarily obscure the embodiments of the invention. The examples used herein are intended merely to facilitate an understanding of ways in which the invention may be practiced and to further enable those of skill in the art to practice the embodiments of the invention. Accordingly, the examples and embodiments herein should not be construed as limiting the scope of the invention.

[0020] The invention as set forth below describes a fire resistant fabric substrate formed of balanced fine corespun yarn, or other non-fire retardant yams, coated or covered with foam, preferably at least one layer of latex foam, as well as a process for applying the foam to the fire-resistant fabric substrate formed of the corespun yarn.

[0021] The invention applies foam, which may include multiple layers and at least one layer of latex foam, directly to a fire barrier fabric substrate of balanced fine corespun yarns or to a fire barrier fabric comprising a double-faced knit corespun yam and other non-fire retardant yarns. The latex foam composite may also preferably be shape formable and retainable to conform to the fire barrier substrate. This unitized layer of latex foam with a fire barrier layer eliminates the barrier application and may also function as an added layer of fire protection in the mattress's construction.

[0022] The fire resistant corespun yarn, which may be knit or woven, includes a core of high temperature resistant continuous filament fiberglass and a sheath of low temperature resistant staple fibers which surround and cover the core. The fiberglass core extends generally in an axial direction and longitudinally of the corespun yarn, while the fibers of the sheath slightly spiral around the core. A few of fibers of the sheath may form a binding wrapper around a majority of the staple fibers.

[0023] The core may include a high temperature resistant continuous filament fiberglass, which constitutes about 20% to 40% of the total weight of the corespun yarn.

[0024] The sheath may include low temperature resistant staple fibers, which constitutes about 80% to 60% of the total weight of the corespun yarn. The sheath may completely cover the core and the yam will take on the characteristics of the fiber which forms the sheath, such as the low temperature resistant staple fibers in this case. The sheath may include blends of natural occurring fibers, such as animal, vegetable or mineral fibers, and or unnaturally occurring fibers, such as cotton, wool, polyester, modacrylic, nylon, rayon, Lycocell, Kenaf, Hemp, Jute, acetate, and blends thereof. The preferred low temperature resistant staple fibers are cotton and polyester. The total practical size of the fine corespun yarn is around 43/1 to 3/5/1 conventional cotton count.

[0025] The invention describes a corespun yarn that may be produced on a Murata air jet spinning apparatus, as disclosed in one or more of U.S. Patents 4,718,225; 4,551,887; and 4,497,167. An air jet spinning apparatus may include an entrance trumpet for feeding the low temperature resistant sheath fibers, one or more drafting rolls, feeding of the high temperature core fibers between two or more drafting rolls, at least one fluid swirling air jet nozzle that may produce air jet spun yarn without any appreciable twist, torque or liveliness, and a delivery roll assembly.

[0026] A single layer foam may include a latex layer. The foam may include multiple layers where at least one layer is latex. Latex is a dispersion of polymeric particles in a continuous phase, where the polymeric particles preferably range in size from 10 to 1,000 nm and the solids content of aqueous latexes is from 20 to 75% by weight. The material in the latex layer may be natural rubber, polybutadiene/styrene, polybutadiene/acrylonitrile, polychloroprene, other synthetic latexes, or a mixture of natural rubber and one ore more synthetic latexes. Polymer containing latexes are available commercially in solids concentration of at least 50%. Mixtures of natural or synthetic latexes can vary from 1 :20 to 6:4.

[0027] The materials of the multilayer foam may be at least one layer of conventional or visco-elastic latex, as well as layers of polyolefm, polyurethane, polystyrene, polyester or mixtures thereof. The first layer of multilayer foam may be of a higher thickness, weight, and or density than subsequent foam layers. Multilayer foam may contain three layers and differing densities may be used in different layers of the multiple layers of foam.

[0028] The foam coating should substantially and completely cover and adhere to at least one side of the fire resistant fabric. The first layer (or the only layer) of the foam resides on the fire resistant fabric and may be vulcanized and or cured to conform the foam to the fabric. The vulcanization or curing of the first layer of foam may occur prior to the addition of more layers of foam on top of the first layer. Vulcanization and or curing render the foam stable for use in end products such as mattresses and upholstery applications.

[0029] This invention also involves a process for applying the foam to a fine textured fire resistant flame barrier lightweight substrate formed of a nonlively nonplied fine balanced corespun yarn. The latex foam may be injected or poured into a first layer of pre-determined thickness onto a fire resistant fabric substrate, and then vulcanized at a first vulcanizing station before moving to subsequent injecting or pouring stations where one or more layers of foam of pre-determined thickness are subsequently injected or poured onto the pervious layer of foam and then vulcanized at a subsequent vulcanizing station before being conformed for use as a mattress or upholstery component.

[0030] The injecting or pouring and vulcanization of foam layers may be repeated for as many layers as are added to the fabric. Foam layers may be sequentially added and vulcanized before other layers are added to it. Alternatively, the vulcanization of multiple layers of foam that are added to the fire resistant fabric may occur concurrently.

[0031] This invention is directed to a continuous process for the manufacture of single or multilayer foam conformed to a fire resistant fabric where the continuity may be provided by moving the foam and fabric along a conveyor belt from one station to the next. The speed of the continuous process may be between 0.25 and 2.5 m/min and more preferentially, between 0.5 and 2.5 m/min, and preferably with three pouring and vulcanization stations.

[0032] The process disclosed includes a way to inject, pour, and spray or other industry known techniques of adding the foam layers onto the fire barrier substrate fabric in a predetermined thickness, size and shape, including into a closed mold.

[0033] Vulcanization may be carried out in any known industry technique such as steam heating, mold heating, microwave heating, or hot air heating, as well as disclosed in U.S. Patent 6,920,643 incorporated herein in its entirety.

[0034] The process may further comprise at least one washing and drying the unitized layer of foam with fire barrier substrate prior to making the end product, such as a mattress, mattress topper, or other upholstery components. The process may include curing in place of or in addition to vulcanization as the method to unitize latex foam with the fire barrier layer.

[0035] While the invention has been described in terms of exemplary embodiments, those skilled in the art will recognize that the invention can be practiced with modifications in the spirit and scope of the appended claims. These examples given above are merely illustrative and are not meant to be an exhaustive list of all possible designs, embodiments, applications or modifications of the invention.