1. Field of Invention
This invention relates to flame retardant materials and a process for their production. More particularly, this invention relates to a flame retardant material containing within its structure or within the structure of a composite attached thereto a superabsorbent material and a process for the production of said materials.
2. Prior Art
Recently there has been enhanced interest in producing highly absorbent materials, particularly for use in products such as sanitary napkins, diapers, bed pads, incontinent garments, etc. In addition, composite materials containing superabsorbent polymers have been designed that combine the high absorbent capacity of the superabsorbent polymers with certain characteristics incumbent in the material which has been combined with the superabsorbent polymer.
For example, U.S. Pat. No. 4,758,466 discloses a foam-fiber composite useful in sanitary napkins as an absorbent. It is comprised of an absorbent structure made from large particles of an amino-ether hydrophilic foam which may contain a superabsorbent material and which is uniformly distributed and heat bonded to a fibrous material, which fibrous material is made from two different kinds of fibers such as a polyethylene and a polyester.
U.S. Pat. No. 4,605,402 discloses a softened absorbent composite structure comprised of a fibrous web containing a superabsorbent material and, in addition, a wicking layer subjected to microcorrugating.
U.S. Pat. No. 4,724,114 discloses a process for the production of a two layer melt blown superabsorbent material comprised of a first wood fiber layer and a second layer containing a superabsorbent material
U.S. Pat. Nos. 4,560,372 and 4,676,784 disclose disposable absorbent products in a layered structure comprised of an absorbent material mixed with a fibrous layer of resilient, synthetic fibers such as polyesters, polyethylene, polypropylene and the like.
U.S. Pat. Nos. 4,454,268, 4,337,181 and 4,133,784 disclose various types of films partially comprised of water absorbent polymers. While these patents disclose starch-based, water absorbent polymers prepared from the combination of starch and ethylene acrylic acid copolymers, they fail to disclose the particular absorbent polymer disclosed herein or the mixture of an absorbent polymer in a composite structure to produce a flame retardant material.
U.S. Pat. No. 3,669,103 discloses water swellable, water insoluble polymeric sorbents for the absorption of aqueous fluids wherein said polymeric sorbents are lightly crosslinked polymers. This patent also discloses the use of a water insoluble polyurethane foam as a support for the polymeric absorbent. However, it fails to disclose the use of a superabsorbent polymer in general, the absorbent polymer disclosed herein or the use of an absorbent polymer in a composite flame retardant material.
U.S. Pat. Nos. 4,731,391, 4,725,628 and 4,725,629 disclose processes for the production of a superabsorbent polyurethane foam. The polyurethane foam is based on an interpenetrating polymer network of a crosslinked polyurethane and a substantially linear addition polymer containing a plurality of chain segments made of functional groups containing repeating units. The functional group of the repeating unit is selected from carbamoyl substitutes and the alkali metal and ammonia salts thereof.
U.S. Pat. No. 4,713,069 discloses a breathable cloth-like barrier which is substantially impervious to liquid water but permeable to water vapor. This patent discloses a barrier especially well suited as the outer cover of certain absorbent articles. However, it fails to disclose the flame retardant, superabsorbent material of the instant invention.
U.S. Pat. No. 4,726,976 discloses a composite substrate which is especially useful as a cover sheet for disposable articles, said substrate is comprised of an inner polyethylene thermoplastic film secured to and between the inner surfaces of a top layer and a bottom layer of a non-woven polypropylene fibrous web. However, it fails to disclose the flame retardant, superabsorbent material of the instant invention.
Polybenzimidazole has been extensively studied because of its high degree of flame retardancy as well as its chemical stability. Polybenzimidazole polymers have been formed into fibers, films and other shaped articles. See for example, U.S. Pat. Nos. 3,699,038, 3,720,607, 3,737,042, 3,841,492 and 3,851,025.
U.S. Pat. No. 4,828,699 discloses a process for the production of microporous polybenzimidazole articles. These microporous polybenzimidazole articles are generally formed by preparing a polybenzimidazole material containing a leachable additive and leaching said additive from said material. Impregnated in these articles may be various absorbent agents including certain chemical encounter agents. However, the use of a superabsorbent polymer within these polybenzimidazole articles is not disclosed, nor is the combining of a polybenzimidazole article in a composite with a second material containing a superabsorbent polymer.