WO1996013994A1

WO1996013994A1 - Odor reducing insole with odor reactant particles

Info

Publication number: WO1996013994A1
Application number: PCT/US1995/014529
Authority: WO
Inventors: Herbert Lapidus
Original assignee: Combe Incorporated
Priority date: 1994-11-08
Filing date: 1995-11-03
Publication date: 1996-05-17
Also published as: AR000086A1

Abstract

An odor reducing insole (1, 4) has a sheet of permeable fabric (2, 5) impregnated with odor reactant particles (3, 6). The fabric may be comprised of permeable or nonpermeable fibers.

Description

"ODOR REDUCING INSOLE WITH ODOR REACTANT PARTICLES"

BACKGROUND OF THE INVENTION

Field of the Invention

This invention relates to an odor reducing insole having a permeable fabric with odor reactant particles, such as sodium bicarbonate crystals, impregnated therein. The invention also relates to an odor reducing insole having a permeable fabric layer impregnated with odor reactant particles which is adhered to an open-celled foam layer having finely ground activated charcoal homogeneously dispersed throughout the foam.

Background Art

It has been long suggested that absorbent insole inserts can be impregnated with deodorants if desired as disclosed in U.S. Patent No. 1,926,283. Various insoles have been designed with this goal in mind. For instance, odor reducing insoles having a layer of nonwoven random fiber or felt impregnated with an odor absorber are known. In that regard, U.S. Patent No. 4,062,131 discloses an insole having an intermediate fibrous layer impregnated with activated charcoal or silica gel which is bound between an open cellular foam layer and an abrasion resistant top layer. This reference, however, does not disclose the use of an odor reactant such as sodium bicarbonate. Moreover the layers are bound together with a binder which may result in deleterious adhesive occlusion of the odor absorbing particles.

U.S. Patent No. 4,709,490 suggests but does not disclose incorporating odor neutralizing substances such as activated charcoal in either layer of an insole having a capillary layer of hydrophobic fibers superimposed on a moisture storing layer of absorbent fibers. The layers of this insole are held together by mechanical needling or adhesive bonding. Again, there is no suggestion of employing an odor reactant, such as sodium bicarbonate, in a single layer of fabric so that adhesive occlusion or the expense of mechanical needling is avoided.

It is well known that activated charcoal reduces odor by adsorption, i.e., the diffusion of odiferous gas into the pores of the carbon particles and adhesion therein. Silica gel is also a known adsorbent which functions in a similar way. On the other hand, it is believed that odor reactants, such as sodium bicarbonate or zinc oxide reduce odors by undergoing a chemical reaction with odiferous compounds which results in the neutralization of their odiferous properties.

Sodium bicarbonate has been used to combat odor in non- insole applications by fixing the sodium bicarbonate on fibrous materials. Those applications, however, have consistently required a binder to fix the sodium bicarbonate on the material. For example, U.S. Patent No. 5,122,407 is directed to an odor-removing cover for absorbent pads wherein the cover is formed of a non¬ woven fibrous material coated with a fluorocarbon polymer that binds an odor absorbing reagent, preferably sodium bicarbonate, to the fibrous material. Similarly, U.S. Patent No. 5,161,686 discloses an odor- absorbing web material which can be a non-woven sheet of synthetic fibers having incorporated therein a molecular sieve material, an alkaline salt, such as sodium bicarbonate, and a binding agent which allegedly allows odorous substances to pass therethrough. This reference suggests employing the web in personal care products such as sanitary napkins and the like. Another use of sodium bicarbonate is disclosed in U.S. Patent No. 5,254,386 which is directed to a self- deodorizing carpet prepared by treating the carpet fibers with an aqueous slurry of bicarbonate salts in combination with a suitable water based polymer latex to ensure that the bicarbonate is bound to the fibers. All these references disadvantageously require the use of a binder which may deleteriously effect the deodorizing efficacy of the sodium bicarbonate deodorizer. Moreover, none of these references disclose or suggest the use of an odor reactant in an insole which is substantially free of a binder so as to provide effective alleviation of foot odor.

An odor reducing insole which minimizes adhesive occlusion is disclosed in co-pending U.S. Patent Application Serial No. 08/234,960, filed April 28, 1994. This application discloses an insole comprised of uniformly oriented tracks of odor reducing particles, such as sodium bicarbonate, separated by contiguously disposed tracks of fused portions which entraps the odor reducing particles between two sheets of fabric. While highly effective, the manufacture of this insole requires the mechanical steps of depositing tracks of odor reducing particles and fusing the two sheets of fabric. Thus, an odor reducing insole having only a single sheet of fabric impregnated with an odor reducing reactant, such as sodium bicarbonate, which is substantially free of adhesive or binding agent would be advantageous.

Accordingly, it is an object of this invention to provide an odor reducing insole having an air permeable fabric layer impregnated with odor reactant particles.

It is also an object of this invention to provide an odor reducing insole with an air permeable fabric layer adhered to an open-cell foam layer, wherein the fabric is impregnated with odor reactant particles and the foam layer contains finely ground activated charcoal homogeneously dispersed throughout.

SUMMARY OF THE INVENTION

The present invention is an odor reducing insole having a layer of air permeable fabric impregnated with odor reactant particles. The odor reactant is preferably sodium bicarbonate. The fabric may be comprised of permeable or nonpermeable fibers. The preferred fabric is a nonwoven fabric comprised of permeable fibers. Since the odor reactant particles of the present invention are substantially free of adhesive or binding agent they provide more effective odor reduction than particles that have been occluded by adhesive. Moreover, the impregnation of the odor reactant particles in a single sheet of fabric is a cost effective method of providing an odor reactant on a substrate to provide reduction of foot odor when used as an insole.

This invention also includes the above-described odor reducing insole in combination with an adhered sheet of open-celled foam with activated charcoal homogeneously dispersed throughout. This embodiment of the invention can advantageously provide an odor reducing insole having two types of odor reducing particles in a single composite. For example, an odor reducing reactant, such as sodium bicarbonate, may be impregnated in the sheet of permeable fabric in combination with the open- cell foam containing the activated charcoal, which is an odor absorber. Tests have shown that an insole having a sodium bicarbonate impregnated fabric layer in combination with a layer of activated charcoal containing open-celled foam is highly effective in reducing isovaleric acid, a known indicator of foot odor.

These and other objects, aspects, features and advantages of the present invention will become apparent from the following detailed description of the preferred embodiments taken in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1 is a perspective view of the odor reducing insole of the present invention.

Figure 2 is a perspective view of another embodiment of the odor reducing insole of the present invention having an adhered layer of open-celled foam with activated charcoal homogeneously dispersed throughout. DESCRIPTION OF THE PREFERRED EMBODIMENTS

Figure 1 shows an example of the odor reducing insole of the present invention 1 which comprises a single sheet of permeable fabric 2 impregnated with odor reactant particles 3. The odor reactant particles 3 are distributed throughout the matrix of the permeable fabric although the proportion of odor reactant particles will generally vary in concentration throughout the fabric matrix. Typically, the particles are more highly concentrated on or near the surface of the fabric.

The sheet of permeable fabric 2 may be a woven or non- woven material. As employed herein, the phrase

"permeable fabric" means a fabric which is permeable to air. Preferably, such permeable fabrics contain interstices located between the fibers of the fabric in which odor reactant particles can effectively lodge after application of a solution containing such particles to the fabric. The fabric material may be comprised of nylon, acrylonitrile, and vinyl copolymers, rayon, polyester, cellulose acetate, cotton, linen, wool, silk, polypropylene or mixtures thereof. The preferred fabric of the present invention is a nonwoven fabric, although any air permeable fabric will suffice. Particularly preferred are fabrics comprised of permeable fibers such as a nonwoven polyester and a cotton/polyester blend. However, surprisingly even permeable fabrics comprised of nonpermeable fibers may be advantageously employed in the present invention. Exemplary permeable fabrics comprised of nonpermeable fibers include polypropylene and the like. Fiber permeability is dependent upon whether a fiber will absorb water. With respect to this invention, permeable fiber means a fiber which will absorb water, whether sprayed, immersed in an aqueous solution or the like. On the other hand, a nonpermeable fiber means a fiber which does not absorb water to any significant degree after exposure to water, a humid atmosphere or the like. Whether a fiber is permeable or nonpermeable is dependent, inter alia, upon its hydrophilicity and porosity. Generally, a permeable fiber is hydrophilic and/or relatively porous, while a nonpermeable fiber tends to be hydrophobic and/or substantially nonporous. Whether a fiber is permeable to water or not can be readily determined by a person of ordinary skill in the art.

Without being held to any theory, it is believed that water-permeable fibers are impregnated with an aqueous solution of the odor reactant particles and thus provide an excellent vehicle for holding such particles. It was widely believed that such impregnation was unlikely in nonpermeable fibers. It was discovered, however, that even permeable fabrics comprised of nonpermeable fibers provide a suitable vehicle for delivering an effective amount of odor reactant particles. It is believed that this unexpected efficacy is a result of the odor reactant particles becoming lodged in the interstices of the permeable fabric matrix, thus providing odor reducing potential despite the use of nonpermeable fibers in the permeable fabric.

The odor reactant particles 3 that are employed in the present invention reduce odor by chemically neutralizing odiferous compounds. Such odor reactants are generally selected from carbonates, bicarbonates and oxides. Exemplary odor reactants include sodium bicarbonate, sodium carbonate, calcium hydroxide, calcium carbonate, magnesium carbonate and zinc oxide. Sodium bicarbonate is particularly preferred as the odor reactant particle of the inventive insole. Other potential odor reactants known in the art can be used, but are generally believed to be less effective.

Typically, the odor reactant particle will be present in the odor reducing insole in an amount ranging from about 5 grams to about 80 grams per square yard of the permeable fabric. When sodium bicarbonate is used as the odor reactant, then it is preferable to employ the approximate amount of 50 to 70 grams per square yard of the permeable fabric. The odor reactant particles illustrated above can also be mixed with other types of odor reducing particles.

The amount of odor reactant particle that is impregnated on the sheet of fabric is dependent upon the particular odor reactant particles employed. Determining the appropriate amount of odor reactant particle is well within the knowledge of those skilled in the art. Generally, the minimum effective amount of odor reactant particle is applied to provide control over the reduction of foot odor.

The odor reducing insole may be prepared by spraying a concentrated aqueous solution or dispersion of the odor reactant on the fabric. The concentration of the solution or dispersion will depend on the final concentration of odor reactant which one desires to impregnate in the fabric. When using sodium bicarbonate, an aqueous solution having sodium bicarbonate present in the amount of about 5 to about 25% w/w of the total solution is prepared. Preferably, the sodium bicarbonate is present in the amount of about 15 to about 25% w/w of the impregnating solution. Generally it has been found that about 25 to 50 percent of the sodium bicarbonate odor reactant in the solution was impregnated into the fabric. The sodium bicarbonate solution, and possibly solutions of other odor reactants, may be heated to enhance the solubility of the odor reactant. Preferably, the sodium bicarbonate solution is warmed to approximately 120°F before application to the fabric.

The odor reactant solution may also be applied to the fabric by immersing the fabric in the solution. When the fabric is immersed, it is generally held in the solution for sufficient time to totally saturate the fabric with reactant solution. The time of immersion is dependent on the type of immersion equipment used and the rate of fabric pick-up.

After the odor reactant is applied, the fabric is dried. Typically the fabric is dried by passing the impregnated fabric through an oven at a temperature of from about 250-325 °F. After the impregnated fabric is dried, insole inserts may be stamped or cut in the shape of a foot by any means known to those skilled in the art. On the other hand, if desired, additional layers of material or foam can be adhered to the impregnated sheet prior to forming the insole shape.

Another aspect of the present invention is illustrated in Figure 2. The odor reducing insole 4 comprises a sheet of permeable fabric 5, impregnated with odor reactant particles 6. In addition, a layer of open- celled foam 7 having activated charcoal particles 8 homogeneously distributed throughout the foam is adhered to fabric 5. This embodiment of the invention provides two types of odor reducing particles in a single insole. Most preferably, odor reducing particles 6 are sodium bicarbonate which provides an odor reducing insole having an odor reacting sodium bicarbonate and an odor absorbing activated charcoal. The open-celled foam 7 having activated charcoal homogeneously distributed throughout can be prepared in accordance with the disclosure of U.S. Reissue Patent No. 29,501 and U.S. Patent No. 5,197,208, both of which are incorporated herein by reference as if their disclosure were fully set forth herein. It is preferable that the sheet of permeable fabric 5 has extending fibers on the side facing the open-cell foam layer to facilitate adherence of the foam layer to the fabric. Significantly, the open celled foam layer can be adhered to the permeable fabric by generating the foam on the fabric. The foam encases the surface fibers of the permeable fabric which binds the foam layer to the permeable fabric.

The Examples which follow are intended as an illustration of certain preferred embodiments of the invention, and no limitation of the invention is implied.

EXAMPLE 1

An odor reducing insole was prepared by spraying an aqueous solution of approximately 15% w/w sodium bicarbonate at a solution temperature of approximately 120°F on a white colored sheet of permeable fabric, Tietex™, a nonwoven polyester fabric available from Tietex Company. After wetting the fabric, it was passed through an oven at about 275°F, until it was dry. A latex slurry capable of forming an open-celled foam and containing homogeneously dispersed activated charcoal was deposited on the impregnated fabric. Thereafter, the slurry was cured to provide an odor reducing composite having sodium bicarbonate impregnated in the permeable fabric and activated charcoal in the open-celled foam layer. The resulting composite was cut into the shape of an insole. EXAMPLE 2

An odor reducing composite was prepared in the manner described in Example 1, except a blue colored Tietex™ permeable fabric was used.

EXAMPLE 3

An odor reducing composite was prepared in the manner described in Example 1, except that a polypropylene permeable fabric having nonpermeable fibers was used instead of the nonwoven polyester.

The odor reducing insoles prepared in Examples 1-3 were tested for efficacy by determining their ability to retain isovaleric acid. As described in U.S. Patent No. 5,197,208, short chain fatty acids, such as isovaleric acid and butyric acid, are recognized in the art as key components of foot odor and thus can be used as markers for evaluating foot odor reduction.

The insoles of Examples 1, 2 and 3, a commercially available open-celled foam insole containing activated charcoal in combination with an untreated polypropylene fabric layer (Commercial Insole #1) , and another commercially available odor reducing insole comprised of activated charcoal in a nonwoven matrix (Commercial Insole #2) were each tested for isovaleric acid retention by packing known amounts of each sample in a stainless steel column and determining the amount of isovaleric acid adsorbed or reacted by gas chromatographic analysis. The results of these tests are set forth in Table 1. TABLE 1

Isovaleric Acid Retained

Composite Material grams/cm² grams/gram % Capacity

Ex. 1 (White Tietex") 7.92 x IO"⁴ 9.03 x 10 ' 0.90

Ex. 2 (Blue Tietex™) 6.11 x IO"⁴ 7.66 x IO"³ 0.77

Ex. 3 (Polypropylene) 4.62 x IO^"4 5.85 x IO'⁵ 0.585

Commercial Insole #1 3.72 x IO^"5 5.68 x IO^"4 0.057

Commercial Insole #2 3.87 x IO"⁴ 3.21 x 10-' 0.321

The insoles of Examples 1 and 2, and Commercial Insoles #1 and #2 were also tested by determining the retention of isovaleric acid by placing each sample in a desiccator containing a known amount of isovaleric acid and weighing the samples periodically over time. The results of these tests are shown in Table 2.

TABLE 2

Is ovaleric Ac id Absorb© (da ys)

Composite Material 3 7 14 21 28 56

Ex. 1 (White Tietex") 19.9 28.5 42.1 51.7 59.4 84.7

Ex. 2 (Blue Tietex™) 18.1 27.2 38.5 46.4 51.5 73.0

Commercial Insole #1 14.5 20.8 27.3 37.3 41.2 54.2

Commercial Insole Wl 14.7 21.9 29.4 33.4 36.1 43.9

The results set forth in Tables 1 and 2 show that the odor reducing insoles of this invention exhibited effective odor reduction capabilities based on isovaleric acid adsorption. In particular, the results show that the inventive insoles impregnated with sodium bicarbonate in the permeable fabric comprised of permeable fibers combined with activated charcoal containing foam were especially effective. Quite unexpectedly, the results show improved efficacy even for inventive insoles comprised of nonpermeable fiber combined with a layer of foam containing activated charcoal. Other variations and modifications of this invention will be obvious to those skilled in the art. This invention is not limited except as set forth in the following claims.

Claims

I claim:

1. An odor reducing insole comprising a sheet of permeable fabric impregnated with odor reactant particles.

2. The odor reducing insole according to Claim 1, wherein the odor reactant particles are selected from the group consisting of sodium bicarbonate, sodium carbonate, calcium hydroxide, calcium carbonate, magnesium carbonate and zinc oxide.

3. The odor reducing insole according to Claim 2, wherein the odor reactant particles are sodium bicarbonate.

4. The odor reducing insole according to Claim 1, wherein the permeable fabric is a non-woven fabric.

5. The odor reducing insole according to claim 1, wherein the permeable fabric is comprised of permeable fibers.

6. The odor reducing insole according to Claim 5, wherein the permeable fabric is a polyester.

7. The odor reducing insole according to Claim 1, wherein the sheet of permeable fabric has fibers extending therefrom.

8. The odor reducing insole according to Claim 1, further comprising a sheet of open-celled foam adhered to the sheet of permeable fabric, said foam having finely ground activated charcoal homogeneously dispersed therein.

9. The odor reducing insole according to Claim 8, wherein the odor reactant particles are sodium bicarbonate.

10. The odor reducing insole according to Claim 5, wherein the permeable fabric is a blend of polyester and cotton.

11. The odor reducing insole according to Claim 1, wherein the permeable fabric is comprised of nonpermeable fibers.

12. The odor reducing insole according to Claim 11, wherein the permeable fabric is polypropylene.

13. An odor reducing insole comprising (i) a sheet of air permeable fabric impregnated with odor reactant particles and (ii) a sheet of open-celled foam adhered to an outer face of the sheet of air permeable fabric, said foam having finely ground activated charcoal homogeneously dispersed therein.

14. The odor reducing insole according to Claim 13, wherein the odor reactant particles are sodium bicarbonate.

15. The odor reducing insole according to Claim 13, wherein the permeable fabric is comprised of permeable fibers.

16. The odor reducing insole according to Claim 15, wherein the permeable fabric is a polyester.

17. The odor reducing insole according to Claim 15, wherein the permeable fabric is a blend of polyester and cotton.

18. The odor reducing insole according to Claim 13, wherein the permeable fabric is comprised of nonpermeable fiber.

19. The odor reducing insole according to Claim 18, wherein the permeable fabric is polypropylene.

20. The odor reducing insole according to Claim 13, wherein the permeable fabric is nonwoven fabric.