Spa cover

Abstract

A spa cover includes an internal heat insulation material having an outer covering which is impermeable to water and water vapor. It absorbs very little water significantly increasing the life of the spa cover. The outer cover is created from a poly halogenated vinyl polymer designed to significantly decrease pore size and water vapor permeability. The outer cover is also laminated from several layers of the poly halogenated vinyl polymer each having a ‘grain’. The grains are angularly offset to further reduce water vapor permeability.

Description

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a Continuation-In-Part of U.S. patent application “Spa Cover” by the same inventors, Eric Albert and Lynda Livingston Ser. No. 10/820,789, filed Apr. 9, 2004 (the “parent application”). This application claims priority to this parent application and incorporates its material as if set forth in its entirety herein.

BACKGROUND OF THE INVENTION

1. Field Of The Invention

The invention generally relates to a spa cover that provides an improved moisture barrier and/or provides improved heat insulation.

2. Discussion of Related Prior Art

Spa covers are widely used to cover spas, or hot tubs, to protect the water within the spa tub from dirt and contamination and to provide a moisture and heat barrier, thus reducing the cost of operating the spa. Spa covers are various sizes and shapes, and are designed to rest upon the top edge of a spa tub. Spa covers are often made up of two connected, folding halves and a hinge provided on the top surface connecting the two halves. The hinge allows the spa cover to be folded.

Spa covers generally include a core material and an outer cover material formed around the core material. The core material is typically made of a light, rigid insulating material. For example, molded, foamed styrene is a commonly used core material. The outer cover is typically made of fabric-reinforced vinyl. The outer cover provides a pleasing cosmetic appearance and creates an outer shell around the core material.

Typically, the fabric-reinforced vinyl material provided at the bottom of the spa cover directly contacts the rim of the spa tub to provide a seal between the spa cover and the spa tub. This seal is meant to prevent the heat of the water within the spa tub from escaping.

During typical operation, the temperature of the water within the spa tub is kept at a high temperature in order to allow persons to bath within the tub. However, since spas are often located outdoors and are designed to be used in all seasons, there is a large temperature difference between the water and the outside air during cold weather. This temperature difference encourages a substantial heat transfer from the hot spa water to the cold outside air. Since the core of the spa cover is made of an insulating material, the main routes of heat escape is through the incomplete sealing between the lower fabric-reinforced vinyl material and the top rim of the spa and through gaps around the hinge where the two cover halves meet.

Another deficiency with existing spa cover systems is that the outer cover material of the spa cover, which is typically fabric-reinforced vinyl material, does not prevent moisture from entering the spa cover core material. In addition, the outer cover can have zippers or similar fastening devices that do not provide a sufficient seal.

As such, these covers allow water to be absorbed into the pore spaces of the insulating, core material (e.g., styrene foam) and, over time, accumulate in the core material much like water would accumulate within a sponge. This accumulated water is difficult to remove and causes the water laden spa cover to become extremely heavy.

In an attempt to reduce the absorption of water from a heated spa, some spa covers have used a barrier layer of plastic film that is hermetically sealed around the entire styrene foam core. This barrier layer is typically a single resin species film, such as low density polyethylene.

While this approach does provide some protection, the moisture permeation rates through the barrier layer are still fairly substantial over the life of a cover. Thus, even with a typical plastic film, the core material will become progressively heavier with the absorption of moisture from the spa water.

The present invention is directed to overcoming one or more of these problems set forth above.

SUMMARY OF THE INVENTION

The present invention may be embodied as an improved spa cover comprising:

• • a) a core insulating material; and
  • b) an outer cover that surrounds the entire core insulating material, wherein the outer cover includes at least two laminate layers each having a ‘grain’ and the grains of the laminated layers having an angular offset with respect to each other.

At least one of the laminate layers is made from poly-halogenated vinyl monomers.

Preferably, at least one of the laminate layers is made from poly-vinylidene chloride (PVDC) resin. This type of cover significantly educes the amount of water vapor passing through the outer cover and significantly reduces the amount of water absorbed into the spa cover thereby significantly extending the life of the spa cover.

BRIEF DESCRIPTION OF THE DRAWINGS

The advantages, nature and various additional features of the invention will appear more fully upon consideration of the illustrative embodiment of the invention which is schematically set forth in the drawings, in which:

FIG. 1 shows a spa cover and a spa tub.

FIG. 2 shows a bottom view of a spa cover and a gasket provided on the bottom of the spa cover.

FIG. 3 shows a spa cover including a multi-layer laminated cover material and a core insulating material.

FIG. 4 is an enlarged view of the multi-layer laminate cover material.

FIG. 5 shows an enlarged view at the molecular level of the relative orientation of several polymer chains.

FIG. 6 shows an enlarged view at the molecular level of the relative orientation of several polymer chains.

DETAILED DESCRIPTION OF THE DRAWINGS

While the invention is open to various modifications and alternative forms, specific embodiments thereof are shown by way of examples in the drawings and are described herein in detail. There is no intent to limit the invention to the particular forms disclosed.

The present invention is a spa cover which includes insulation material; however, it is completely enclosed in a waterproof, water vapor resistant outer cover material. The outer cover is made from a material which is a laminate that may be co-extruded. The longitudinal ‘grain’ of each laminate layer of the materials is angularly offset to reduce water vapor permeability.

A preferred material to be used for the laminate is a polymers made from poly halogenated vinyl monomers, such as polyvinylidene chloride (PVDC). These are very resistant to diffusion of gases, including water vapor.

FIG. 1 shows a first non-limiting embodiment of the first aspect of the invention in which spa cover is provided on a spa tub 50.

A gasket 20 (shown in FIG. 2) provides an improved seal between the spa cover 10 and a rim 60 of the spa tub 50. The spa cover 10 includes a first cover portion 12 and a second cover portion 14 and a hinge 16 provided on the top surface 10a of the spa cover 10. The hinge 16 connects the two portions 12, 14 and allows the spa cover 10 to be folded.

Since these spa covers gain weight as they absorb water, they can become very heavy. Therefore, they are typically made of two parts with a center hinge. The separation between portions 12 and 14 leaks heat.

Since the present invention reduces water absorption, it is possible to make a single piece spa cover which will minimize heat loss.

As shown in FIG. 2, the gasket 20 is applied to a lower surface 11b of the spa cover 10 as a continuous “U” shape on each portion 12, 14 of the cover 10.

As stated in the “Background of the Invention”, the spa covers absorb water and become very heavy and must be replaced periodically. Water proofing against liquid water does not stop water from building up in the cover. Numerous types of outer coverings have been used, all with the same result. Even when materials known to be a barrier to liquid water were used, it has been shown that water still absorbs into the cover insulating material causing it to be replaced.

Many waterproof materials are permeable to water vapor. When water vapor passes through waterproof materials, it is in the vapor form and dissipated undetected into the atmosphere.

In the present use, however, water vapor passes through an outer cover and into the core material, which is typically insulation. If the conditions in the cover insulation are cooler and less humid, the vapor condenses into a liquid. The liquid cannot pass back through the barrier layer and into the spa and is trapped in the insulation.

One way to reduce this accumulation of water in the cover insulation is to prevent not only liquid water from passing through the outer cover, but also to prevent water vapor from passing through the outer cover.

The most likely material to be used is a plastic material. Many plastics have some small amount of vapor permeability. This small amount of permeability, over a long period of time causes the spa cover to be waterlogged over two or three years causing it to be replaced.

FIG. 3 shows a non-limiting embodiment of the second aspect of the invention. According to a second aspect of the invention, a multi-layer, waterproof outer cover material 110 is hermetically sealed surround the entire core material 13 of a spa cover 10. This multi-layer, waterproof cover material 10 protects the core material 13 of the spa cover 100 from moisture penetration and absorption. As discussed above in the Background Section, the core material 13 is typically an insulating material, such as a foamed styrene, which can become waterlogged.

FIG. 4 is an enlarged view of the waterproof laminate outer cover material of FIG. 3. The cover material 110 consists of multiple, diverse thin waterproof layers 11a, 11b, 11c. The diverse layers can be, for example, layers of different materials and/or layers of the same material that are laminated at different orientations with respect to each other. These layers 10a, 10b, and 10c are each preferably a plastic material.

FIG. 5 shows a general enlarged schematic view of a polymer 1000. Polymer chains 1003, 1005, 1007 are constructed from a number of monomers 1001 which are linked end to end. The polymer chains 1003, 1005, 1007 are typically several orders of magnitude longer than each monomer 1001.

Also, these polymer chains 1003, 1005, 1007 tend to align parallel to each other causing a general ‘grain’ to the polymers. Locations between the polymer chains 1003, 1005, 1007 may cause spaces. If the polymers are extruded or stretched into sheets thin enough, the spaces of several layers above each other, such as chains 1003, 1005, 1007 can produce passages through the material called “pores” 1009. These pores 1009 allow the passage of gasses and, if large enough, also liquids through the material.

It was noted that some polymers having side chains which extend perpendicular to the length of the chain, may inhibit the formation of “pores”, and therefore decrease permeability.

One such polymer group is halogenated polyvinyls. One such member of the group is poly-vinylidene chloride. Its monomer has “ . . . a carbon-carbon double bond but has two chlorines on one of the carbon atoms. The polymer formed from the addition polymerization of this material has excellent barrier properties, especially against oxygen gas, and is used extensively as a food wrap”, Plastics, Materials and Processing, by A. Brent Strong, Third Edition, copyright 2006.

In order to further reduce the gas permeability of the cover material 110, the layers 11a, 11b, 11c of the laminate are fused together with an angular offset between the layers.

In FIG. 6 it shows a few chains 1003, 1005, 1007 overlaying three other chains 1011, 1013, 1015, offset at an angle. Due to the geometry, the monomers of the overlying chains 1011, 1013, 1015 block the passageways between the chains 1003, 1005, 1007, further reducing permeability through the laminated material.

In order to keep this offset orientation, the layers are co-extruded at these offset angles. In a preferred embodiment, the ‘grain’ of the laminates is offset by 45 degrees. It is possible to use different angular orientations for different embodiments.

The use of layers of different materials provides a superior moisture barrier without the thickness or weight that would be necessary if a single material was used. By laminating the thin layers together, a superior moisture barrier is formed due to the synergistic effect of the physical and molecular properties.

There are low density polymers, such as low density polyethylene (LDPE) and high density polyethylene (HDPE). The HDPE packs the polymer chains in closer proximity, reducing the pore sizes between the chains. LDPE is typically used in the prior art covers.

HDPE may be used as one or more of the laminate layers of the present invention to reduce pore size and further reduce water vapor permeability.

Typical improvement in moisture penetration rates are on the order of 100 times lower than single species resins such as polyethylene. Just as plywood becomes much stronger than the individual layers, a multi-layer barrier film, or co-extruded material, provides a far lower moisture permeation rate, and protects the core material over a longer period of time, compared with a single waterproof material.

Some non-limiting examples of extremely thin multi-layer resins that include different materials are PVDC resins commercially marketed as SARANEX. These resins are extremely thin, about 1 to 5 mils (1 mil=0.001 inch) thick. However, the invention is not limited in this respect and other multi-layer films can be used, such as a laminated barrier including a polyethylene film sandwiched between SARANEX films.

Although the food industry utilizes thin, lightweight multi-layer laminated barrier films, such as SARANEX, in order to protect foodstuffs, a multi-layered barrier film has not been utilized in the spa industry.

Another preferred material is Valeron™ from the Valeron Corporation in Houston, Tex.

HDPE was used to make a multi-layer laminate outer cover having the ‘grain’ of the laminate sheets angularly offset by 45 degrees. The sheets were 2 mils each in thickness. An adhesive was used to bond the layers together.

The material was coated with molten polyethylene to enhance its ability to attach to itself and other materials.

It was sent for testing at Mocon testing Service in Minneapolis, Minn., an independent testing laboratory, for testing its water vapor permeability.

An industry standard outer covering material was also sent for the same testing.

Two samples of the laminate material according to the present inventions and two samples of the industry standard outer cover material were tested using a gas with 100% relative humidity at 104 Degrees F.

The industry samples had water vapor transmission rates in gm/(100 in²-day) of 0.329 and 0.338.

Similarly, the samples of the laminate according to the present invention had water vapor transmission rates in gm/(100 in²-day) of 0.0868 and 0.0899.

This shows that the industry standard material allows from 366%-389% more water vapor to permeate into the spa cover than the present invention. This indicates that the material of the present invention can cause the spa covers to last 3-4 times longer than the current spa covers.

The invention may also be embodied in different ways. For example, a barrier including layers of the same material laminated at different orientations can also be used to provide the enhanced moisture protection.

Also, different angular offsets may be employed between the laminate layers. A multi-layer outer cover can employ two or more layers oriented at angles up to 90 degrees with respect to each other.

It is of course understood that departures can be made from the preferred embodiments of the invention by those of ordinary skill in the art without departing from the spirit and scope of the invention that is limited only by the following claims.

Claims

1. An improved spa cover comprising:

a) a core insulating material; and

b) an outer cover that surrounds the entire core insulating material, wherein the outer cover includes at least two laminate layers each having a ‘grain’ and the grains of the laminated layers having an angular offset with respect to each other.

2. The improved spa cover of claim 1 wherein at least one of the laminate layers is made from poly-halogenated vinyl monomers.

3. The improved spa cover of claim 1 wherein at least one of the laminate layers is made from poly-vinylidene chloride (PVDC) resin.

4. The improved spa cover of claim 1 wherein at least one of the laminate layers is made from a high density polyethylene (HDPE) resin.

5. The improved spa cover of claim 1 wherein the outer cover exhibits a water vapor permeability of less than 0.09 gm (100 in2-day).

6. The improved spa cover of claim 1 wherein the angular offset between the grains of at least two of the laminate layers have angular offsets of up to 90 degrees.

7. The improved spa cover of claim 1 wherein the angular offset between the grains of at least two of the laminate layers have angular offsets of approximately 45 degrees.

8. The improved spa cover of claim 1 wherein said cover is a one-piece cover.

9. The improved spa cover of claim 1 wherein said spa cover does not include a hinge.

10. The improved spa cover of claim 1 wherein the laminated layers are of the same material.

11. The improved spa cover of claim 1 wherein the laminated layers are of a different material.

12. A method of creating an improved spa cover comprising the steps of:

a) providing a core insulating material;

b) creating an outer cover having at least two laminate layers each having a ‘grain’ and the grains of the laminated layers having an angular offset with respect to each other; and

c) covering the entire core insulating material with the outer cover material to create a waterproof and air-tight spa cover.

13. The method of creating an improved spa cover of claim 12 wherein the step of creating an outer cover includes using laminate layers made from a poly-halogenated vinyl monomers.

14. The method of creating an improved spa cover of claim 12 wherein the step of creating an outer cover includes using laminate layers made from poly-vinylidene chloride (PVDC) resin.

15. The method of creating an improved spa cover of claim 12 wherein the step of creating an outer cover includes using laminate layers having grains offset up to 45 degrees.

16. The method of creating an improved spa cover of claim 12 wherein the cover is a one-piece cover.

17. The method of creating an improved spa cover of claim 12 wherein the cover does not include a hinge.

18. The method of creating an improved spa cover of claim 12 wherein the step of creating an outer cover includes using laminate layers that are the same material.

19. The method of creating an improved spa cover of claim 12 wherein the step of creating an outer cover includes using laminate layers that are different materials.