Apparatus and methods for the attachment of materials to polyurethane foam, and articles made using them

Abstract

One aspect of the present invention relates to a laminated foam product, wherein the adhesive binding the foam to the laminate comprises the mixture from which the foam is made. Another aspect of the present invention relates to methods for making a laminated foam product. A third aspect of the present invention relates to an apparatus for making a laminated foam product.

Description

BACKGROUND OF THE INVENTION Composite articles having a plurality of layers, especially those used to make wound dressings, garments, and industrial composites, could be vastly improved if there was a method for adhering the substrate to the foam layer while still maintaining the malleability and characteristics, e.g., biocompatability, of the original foam. For example, it has been difficult to construct safe, durable wound dressings. Moreover, industrial composite articles with increased durability, malleability and strength have been sought for many years. What is needed is a method of adhering the substrate to the polymer foam without adversely affecting the desired properties of the original untreated foam or substrate, e.g., biocompatibility or moisture vapor transfer rate. Methods for achieving adhesion between layers of a composite material typically involve a combination of surface modification techniques. Several types of surface modification exist. One type of surface m...

AI Technical Summary

Benefits of technology

Another aspect of the present invention relates to an apparatus used in the production of the composite foam material. This apparatus generally comprises: spindles that contain the substrate and foam feedstock, a roller which supports the materials to be bonded; a spray gun for application of the adhesive; a roller to guide application of the polymeric foam; and a spindle to collect the foam-substrate composite product. This apparatus offers the advantage that the adhesive foam can be rapidly applied in a substantially uniform manner and does not require an additional step or materials to distribute the adhesive.

Another aspect of the present invention relates to a material comprising a polymeric hydrophilic foam bound to a substrate by an adhesive, wherein the adhesive is a hydrophilic polyurethane foam precursor that cures to become such a hydrophilic foam. The composition of the adhesive foam may be the same or different than the composition of the polymeric hydrophilic foam bound to the substrate. This composite material has superior physical properties compared to composite materials formed using traditional non-porous / non-hydrophilic adhesives and is less toxic than some hydrophilic polymer adhesives cured by exposure to humidity. For example, the adhesive foam of the present invention prevents the composite material from containing a “hard” layer that often causes discomfort for a patient wearing a medical garment or wound dressing made of such a composite material. In addition, traditional adhesives can reduce the moisture vapor transmission rate (MVTR) through the adhesive layer and trap the fluid in the foam. The fluid may arise from perspiration or from liquid exuded from the wound. The buildup of fluid in the foam is mitigated when the adhesive is also a foam that allows for moisture vapor transmission. The use of foam adhesives is advantageous because some hydrophilic foams are known to swell when wet (for example, approx. 20-30% each dimension or more) and the use of a foam adhesive ensures that the adhesive will swell in proportions similar to that of the bulk foam component of the composite material. This property effectively prevents a “bimetallic strip” effect, such as curling and cupping of the composite material (e.g., medical garment).

The use of a polyurethane foam adhesive layer is also advantageous because regulatory approval requirements can arise when a new material (e.g., an adhesive) is introduced into an approved product (e.g., a medical foam). Hence, utilization as an adhesive of a foam that has already been approved for medical use would reduce costs associated with approval of the composite material for medical use.

Another aspect of the present invention relates to a composition comprising a substrate coated with a thin layer of a hydrophilic polyurethane foam. In a preferred embodiment, the hydrophilic polyurethane foam is prepared from a prepolymer mixture of Trepol®, HYPOL™, or Prepol. The substrate is a textile or non-woven material. In a preferred embodiment, the substrate is cotton, wool, linen, rayon, or nylon. The composite materials of the invention readily transmit moisture vapor and will be particulary useful in the preparation of various various garmets, blankets, protective barriers, and wound dressings.

Problems solved by technology

This advance is particularly important for hydrophilic or hydrophobic polyurethane foams because it can be difficult to find non-toxic, durable adhesives to bond materials to these types of foam that do not alter the characteristics of the material.

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