Thermochromic waterproof apparel

Description of equivalent WO 2004107886 A2

THERMOCHROMIC WATERPROOF APPAREL

BACKGROUND INFORMATION

FIELD OF THE INVENTION

[0001] The field of the invention relates to waterproof outerwear. More particularly, the invention relates to waterproof outerwear made of flexible sheet material, such as elastomeric PVC, polyurethane elastomer, or other thermoplastic alloys, that changes its appearance as the ambient temperature changes.

DESCRIPTION OF THE PRIOR ART

[0002] Conventional waterproof apparel, which includes raincoats or jackets, rain hats, rain pants and footwear, is generally constructed of a waterproof material. The types of material used for such waterproof apparel include woven and non-woven material, material that is inherently waterproof, such as PVC or other polymeric extruded or calendered sheet material, as well as woven cotton material that is surface- treated with a waterproofing coating.

[0003] Essentially, the purpose of waterproof apparel is to protect the wearer from the external elements. Many types of material are already known that satisfy this purpose adequately. It is also important that waterproof apparel be comfortable to wear and aethetically pleasing and it is in this area that waterproof apparel is often less than satisfactory, particularly for children. Children often refuse to wear traditional waterproof apparel because it is found to be cumbersome and unappealing. Thus, children are often exposed to undesirable weather elements without benefit of protective clothing. [0004] It is, therefore, desirable to provide waterproof apparel that provides an entertaining and surprising effect that is appealing to children. One such entertaining and surprising effect is to provide for a color change in the fabric of the waterproof apparel, depending on the temperature or on sunshine. It is know to effect a change in the color of a material by the use of thermochromic dyes or inks.

[0005] Thermochromic dyes allow a reversible color change as a function of temperature change. For instance, a thermochromic dye incorporated into a material appears transparent until the material reaches a certain temperature, at which time, due to an electron exchange, the color pigment of the thermochromic dye is released from encapsulation and the material takes on the color of the pigment. Thermochromic materials-can 43e G*mulatedJ ' ha gelcαlorj^ below a predefined temperature.

[0006] Thermochromic dyes and their use in PVC sheet material are known. The Pilot Ink Co. teaches thermochromic dyes and methods of incorporating them into plastic materials. See, for example, Nakasuji et al. (U.S. Patent 4,028,118; 1977) and Kito, et al (U.S. Patent 4,421 ,560; 1983), which disclose thermochromic sheets comprising a thermochromic layer containing thermochromic material that is laminated onto a backing material. By using a suitable technique, such as adding the thermochromic material to a polymeric substance, the resulting mixture is then made into a film that can be heat pressed onto the backing material. A protective layer is laminated onto the thermochromic layer to make it weather resistant. The protective layer may be a film of polyvinyl chloride (PVC). These patents are herein incorporated by reference.

[0007] Shibahashi et al. (U.S. Patent 5,858,914; 1999) discloses applying thermochromic-dye-containing images to a boot. The boot appears to be a uniform, solid color at room temperature, for example, but when the temperature drops below a pre-defined temperature, the images then become apparent. Doolan (U.S. Patent 6,196,241 ; 2001) discloses an umbrella having a canopy onto which thermochromic- dye-containing images have been applied. When the temperature of the umbrella fabric drops because of the cooling effect of the rain, the images become visible on the canopy. None of the prior art, however, discloses waterproof apparel that is made of a flexible fabric and that incorporates thermochromic properties and/or ultraviolet- sensitive properties.

[0008] What is needed therefore is waterproof apparel that provides adequate protection against the elements of the weather, but that is, at the same time, comfortable to wear. What is further needed is such apparel that is aethetically appealing to the wearer. What is yet further needed is such waterproof apparel that is parti€ularly appea]ing^nd.eøtejlaij Jng.iQ.chililr_ea,.

BRIEF SUMMARY OF THE INVENTION

[0009] For the reasons cited above, it is an object of the invention to provide waterproof apparel that provides protection against rain and is comfortable to wear. It is a further object of the invention to provide such apparel that is aesthetically appealing to the wearer. It is a yet further object to provide such apparel that is particularly appealing and entertaining to children.

[0010] The above-cited objects are achieved by providing waterproof apparel that is visually appealing and engages the interest and pleasure of the wearer by providing a change in appearance as a function of ambient conditions. The waterproof apparel according to the invention is constructed of flexible PVC film that contains thermrochromic properties such that, when the temperature of the waterproof apparel changes beyond a set limit temperature, the waterproof apparel changes appearance.

[0011] The change in appearance of the waterproof apparel is effected by incorporating one or more thermochromic dyes into PVC resin that is extruded, calendered, or cast into sheet material for use in the fabric for the waterproof apparel. The thermochromic dye remains transparent within a certain temperature range, but, when the ambient temperature, and thus, also the temperature of the waterproof apparel, changes beyond a pre-defined limit, the dye then becomes visible. The ability to visibly see the change in ambient temperature provides a fun and surprising experience for the wearer of the waterproof apparel.

[0012] The waterproof apparel according to the invention is constructed of flexible PVC material that includes at least one thermochromic dye. For example, a raincoat that is pink at room temperature changes to purple when the temperature of the PVC material drops below 62 degrees F.

[0013] It is within the scope of the invention to include more than one dye in the material, so that various effects are obtainable. So, for example, the pink raincoat described above changes to another color, say a cool blue, when the temperature rises above 68 degrees F. It is also possible to incorporate a second thermochromic dye within the PVC resin to be extruded such that a variegated pattern appears on the apparel. The variegated patterns include moire effects, stripes, or random appearances of one or more colors that provide a "mottled" effect.

[0014] Dyes that are sensitive to ultraviolet light, i.e., photochromatic dyes, are known and it is within the scope of the invention to provide waterproof apparel that includes photochromatic properties, along with the thermochromic properties described above. Thus, a raincoat according to the invention changes color when the temperature rises above or falls below pre-defined limit temperatures, but also changes color when the ultra-violet light level rises above or falls below pre-defined limits.

[0015] The waterproof apparel according to the invention includes coats, jackets, pants, hats, skirts, boots or shoes, shoe coverings, shoulder bags, tote bags, and backpacks. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] FIG. 1 illustrates a raincoat have a color at room temperature.

[0017] FIG. 2 illustrates the raincoat of FIG. 1 , having changed its color due to a change in ambient temperature beyond a pre-defined temperature limit.

[0018] FIG. 3 illustrates the raincoat of FIG. 1 evidencing a moire effect created by the simultaneous activation of two or more thermochromic dyes.

[0019] FIG. 4 illustrates the raincoat of FIG. 1 evidencing a mottled effect created by the simultaneous activation of multiple thermochromic dyes.

DETAILED DESCRIPTION OF THE INVENTION

[0020] In the preferred embodiment of the invention, the batch material for fabricating a flexible PVC sheet material includes the polyvinyl chloride polymer and/or copolymer resin, compounded with plasticizers as needed to provide a supple sheet suitable for waterproof apparel, and one or more thermochromic dyes. The thermochromic dyes are conventional dyes, such as dyes provided by Keystone Aniline Dyes. The dyes are added to the batch material in the form of microencapsulated particles, in which they appear transparent, i.e., are invisible, as long as the ambient temperature remains within a base temperature range. When the temperature exceeds a pre-defined limit, the dye is released from the encapsulation and now becomes visible. This process of releasing the particles of dye is reversible, as taught by the Pilot Ink Co. patents mentioned above, so that when the temperature reverts back to the base temperature range, the dye is again encapsulated and becomes, again, invisible.

[0021] FIGS. 1 and 2 show a first embodiment of a waterproof apparel 10 according to the invention. The waterproof apparel 10, in this particular illustration a coat, is constructed of a flexible, PVC sheet material containing a thermochromic dye that is co- extruded with the PVC sheet material. FIG. 1 shows the waterproof apparel 10 at room temperature, having a first solid color 3 at room temperature. FIG. 2 shows the waterproof apparel 10 having a second solid color 5 after the temperature has dropped below a predefined temperature limit, such as 65 degrees Fahrenheit. It should be understood that specific temperature limits given herein are arbitrary and for purposes of illustration, and that the scope of the invention includes temperature limits within the range of possible limits of conventional thermochromic dyes and/or inks.

[0022] In a second embodiment, the waterproof apparel 10 is constructed of a flexible thermochromic PVC sheet material that includes a first thermochromic dye that becQmes^pparentata-rirstteraperøtur cba that becomes apparent at a second temperature change limit. For example, the flexible PVC sheet material has a base color of yellow. When the temperature drops below 65 degrees Fahrenheit, the color of the sheet material changes to blue; when the temperature rises above 72 degrees Fahrenheit, the color changes to green. It is understood that many variations of the present invention are possible, using numerous thermochromic dyes and choosing any number of feasible temperature limits.

[0023] FIGS. 3 and 4 illustrate variations of the waterproof apparel 10, depending on how the thermochromic dyes are incorporated into the PVC base material and how many colors are used. FIG. 3 shows the waterproof apparel 10 that evidences a moire effect when the temperature changes beyond the predefined temperature limit. Rather than mixing the thermochromic dyes in with the PVC resin, the dyes are injected into the extrusion process through a series of nozzles or injectors, thereby creating a striped and/or wavy pattern in the PVC material. FIG. 4 illustrates another variation in which multiple colors are incorporated into the base material in a random pattern, creating the mottled effect with the ambient temperature rises above or falls below the respective temperature limit. [0024] Analogous to the art of incorporating thermochromic dyes into PVC flexible sheet material, photochromatic dyes, that is, dyes that are sensitive to ultra-violet light (UV), may also be included as microencapsulated particles into the batch material for fabricating the PVC sheet material, whether it be by extrusion, calendering, or coating processes, such as curtain, solution, or roller. Thus, the PVC fabric for the waterproof apparel 10 may include photochromatic dyes, either alone or in combination with thermochromic dyes. It is within the scope of the invention to provide waterproof apparel 12 that is made of a flexible PVC or other elastomeric polymer fabric that changes color as a function of the amount of ambient UV light. If the sky is overcast, the waterproof apparel 12 evidences a base color. When the sun comes out, the color of the waterproof apparel changes to a second color. It is within the scope of the invention to provide waterproof apparel that includes a combination of thermochromic dyes and photochromatic dyes.

[0025] The material used for the waterproof apparel 10 preferably has a supple drape to it and feels comfortable against the skin of a wearer. For this reason, additives or a backing may be applied to the flexible PVC or other polymeric material to provide a feel to othe waterproof apparel 10 that is akin to a woven fabric. Nylon is a suitable additive and a suitable backing material may be made of olefin polymers, copolymers, or terpolymers.

[0026] The embodiments of the invention mentioned herein are merely illustrative of the present invention. It should be understood that a person skilled in the art may contemplate many variations in construction of the present invention in view of the following claims without straying from the intended scope and field of the invention herein disclosed.