CA2100518C - Improved cushion receptacle for fluid and method of making the same - Google Patents

Abstract

IMPROVED CUSHION RECEPTACLE FOR FLUID AND METHOD OF
MAKING THE SAME
Abstract of the Disclosure A method for fabricating a cushioned receptacle for fluids. A fiberglass reinforced polyester resin base is fabricated, preferably by a resin transfer molding process. A composite, flexible polymeric skin is fabricated in two, preferably three, steps. In the first step, a first coat, comprising two layers of an elastomeric resin, such as an elastomeric polyurethane is applied to a form that has a configuration generally complimentary to the configuration of the base. A second coat of an elastomeric resin, such as an elastomeric polyurethane is applied to the first coat, while the first coat is still on the form. Preferably, thereafter, a third coat of a foamable resin, such as a foamable polyurethane is applied to the second coat. In one embodiment, the base is assembled with the coated form so that a cavity is defined therebetween, and a flexible cellular foam, such as a polyurethane, is injected into the cavity where it foams. In another embodiment, a binder coat is applied to the third coat and a layer of fiberglass is sprayed onto the binder coat.

Description

210~

IMPROVED CUSIIION RECEPTACLE FOR ~LUII) AND METHOD OF
MAKING T~IE SAME
Field of the Invention This invention generally relates to methods of making cushioned receptacles S for fluids, and more particularly, to methods of making cushioned tubs that have a laminar structure, including a composite flexible polymeric skin, a relatively rigid base, and a flexible cellular foam sandwiched between and bonded to the composite skinand the base.
Back~round of the Invention Cushioned bathroom articles, such as bathtubs, shower stalls, sinks, and the like, are known in the prior art as being formed from a laminated structure having a flexible polymeric layer, typically of vinyl, a base, typically made of a fiberglass reinforced polyester resin, and a cellular foam sandwiched between the flexible polymeric layer and the base. Such cushioned bathroom articles are cor.1parable in appearance with ccnventional steel or iron, porcelain coated bathroom receptacles, and the foam provides improved thermal and acoustic insulation over such conventional receptacles. Moreover, when this composite structure is applied to bathtubs, the combination of the flexiUe polymeric outer layer and the foam makes it unlikely for anyone to slip in the tub, and cushions any fall that does occur.
For a number of reasons, such cushioned bathroom articles have not found widespread acceptance. Perhaps the most important of these reasons is the fact that the cushioned bathroom articles known to the prior art were not able to stand up to the rigors of actual use. For example, the prior art cushioned bathroom article described in U.S. Patent No. 4,289,717 describes a flexible composite polymeric skin ~ "
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210~8 that includes an outer layer of vinyl. When vinyl is used as the outer skin, breakdown of the skin can occur because the physical properties of the flexible skin, such as tensile strength, elongation strength, and abrasion resistance make the skin more susceptible to breakdown under the rigors of actual use. In addition, vinyl tends to S lose plasticizer over time, resulting in a hardening of the flexible polymeric skin. Also, the curing times required for vinyl resins contribute significantly to the length of the processing times.
Another reason that prior cushioned bathroom articles did not find widespread acceptance was due to problems encountered in the manufacturing process. For 10 example, the process described in the '717 patent produced a high number of rejects due to leakage of foam between the base and the required flexible composite skinduring the manufacturing process. Furthermore, the seal that was used to try andprevent leakage according to the '717 patent involved labor-intensive steps. Theproduction of numerous rejects and the labor costs involved in attempting to prevent 15 foam leakage contributed significantly to the costs of manufacturing.
As can be seen from the foregoing, there continues to be a need for cushioned receptacles for fluid, such as tubs, that are made from materials that are physically tough enough to withstand actual use conditions and which maintain their physical characteristics over extended periods of time consistent with the lifetimes of the 20 manufactured articles. As is always the case, there is also a need to improve the economics of manufacture by reducing the length of time required to complete thearticles and reduce the number of rejects produced.
Summarv of the Invention The method formed in accordance with the present invention for fabricating a 25 cushioned receptacle for fluid includes the steps of fabricating a base having a shape that is generally similar to the shape of the receptacle. A flexible composite skin is formed by applying a first coat of a urethane polymer onto a form that has a shape complimentary to the receptacle. A second coat of urethane polymer is applied onto the first coat. Preferably, a third coat of a foamable polymeric resin is applied onto 30 the second coat to provide "body" to the skin. The resulting composite skin on the form is mated with the base to provide a cavity between the base and the foamable polymeric resin. The cavity is then filled with a foamable polymeric resin in accordance with the present invention. Alternatively, a method formed in accordance with the present invention includes applying the first coat, second coat, and third coat 35 as described above, with the third coat being thicker than in the embodiment described above. Thereafter, a binder coat is applied to the foamable polymeric resin to lCP~P.WC

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2100~8 facilitate bonding between the foamable polymeric resin and fiberglass which is applied over the binder coat.
In a preferred aspect, the urethane polymer of the first coat and the second coat are elastomeric urethanes that are not foamable.
In addition, a preferred aspect of the method formed in accordance with the present invention is the use of an integral silicon rubber seal that seals the base to a frame for the base, as well as seals the frame to the form.
In another aspect, the present invention relates to the cushioned receptacle forfluid made in accordance with the method of the present invention. The receptacle formed in accordance with the present invention comprises a base, a first layer of an elastomeric urethane, a second layer of an elastomeric urethane applied to the first layer, and a layer of a foamed resin between the base and the second layer of .
elastomeric urethane. In a preferred aspect, a third layer of a foamable urethane is applied to the second layer and the foamed resin is sandwiched between the base and the third layer of foamable urethane. In an alternative embodiment, the first, second, and third layers of urethane are provided as described above; however, the third layer of a foamable urethane is thicker than the third layer described above. In the alternative embodiment, a binder coat is applied to the third layer of foamable urethane and then a layer of fiberglass is provided on the binder coat.
Brief Description of the Drawin~s The present invention can best be understood by reference to the following portion of the specification, taken in conjunction with the drawings, in which:
FIGURE 1 is a cross-sectional view of a two-part mold used to fabricate a - :
fiberglass reinforced polyester resin bathtub base by a resin-transfer molding process;
FIGURE 2 is a pictorial view of the fabricated base; ~ ~ ~
FIGURE 3 is a pictorial view of a form for fabricating the composite, flexible ~ .:
polymeric skin;
FIGURE 4 is an exploded pictorial view showing an assembly of the form with the composite polymeric skin thereon, the base and a frame for assembly of the base .
with the form for purposes of forming, in situ, the cellular foam in the cavity between the base and the form; ~ .
FIGURE S is a cross-sectional view of the assembled form, base, and frame; ~ -FIGURE6 is a cross-sectional view showing details of the laminated components of the composite skin along the arms of the receptacle;
FIGURE 7 is a pictorial view showing the fabricated cushioned receptacle;

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210~18 FIGURE 8 is a cross-sectional view of the fabricated cushioned receptacle taken along the line 8-8 in FIGURE 7; and FIGURE 9 is a cross-sectional view of the lay-up of an alternative ernbodiment for a receptacle formed in accordance with the present invention.
Detailed Description of the Invention While the present invention is described with reference to the construction of acushioned bathtub, it should be understood that the invention also finds application in the fabrication of other cushioned receptacles, particularly those used in the bathroom, such as shower stalls, sinks, "whirlpool" tubs, hot tubs, spas and the like.
The first step in the fabrication process is the construction of a base having aconfiguration generally similar to that of the finished cushioned bathtub that provides a desired degree of rigidity and strength therefor. Referring to FIGURES 1 and 2, base B is fabricated from polyester resin and reinforcing fiberglass fabric by aconventional two-part mold, resin injection process. In FIGllRE 1, female part 10 of a two-part mold is designed to sit upon a flat surface and includes central wallportion 10a surrounded by peripheral flange portion 10b. Likewise, male part 12 of the two-part mold indudes central wall portion 12a, complimentary to wall portion 10a, and surrounding peripheral flange portion 12b, which is generally complimentary to flange portion 10b. In assembly, male part 12 fits into female part 10, with flange portions 12b and 10b abutting along the peripheries at 16, and with there being defined between male part 12 and female part 10 a cavity 18 whose configuration is that of the desired bathtub base B.
To fabricate bathtub baseB, a resin transfer molding process is employed Base B can be formed from polyester resins that include fillings, such as fire retardants. Suitable polyester resins include those sold under the designation W1827 by Gwil Industries, Winfield, British Columbia or CC154 available from Reichold of Port Moody, British Columbia. To fabricate bathtub baseB, the opposed inside surfaces of female part 10 and male part 12 are coated with a suitable parting agent, such as that sold under the designation "Frekote 700," by Dexter Adhesives, Seabrook, New Hampshire. A fiberglass mat is precut according to a predeterminedpattern, and then laid into female part 10. Preferably, a single layer of about 2 to 2.5 oz. per square foot, continuous strand fiberglass mat (available from Owens-Corning) is used on the side walls. Two plies of the fiberglass mat are used in high stress areas, such as the floor and end walls. Then, male part 12 is assembled with female part 10 and secured thereto by a plurality of clamps 14. Polyester resin and an appropriate catalyst, both in liquid form, are mixed in an appropriate apparatus and IUD~

2100~18 then force injected through aperture 20 in central wall portion 12a of male part 12, into and throughout cavity 18. Vfnt holes (not shown) at the corners of male part 12 allow air to escape from cavity 18 during injection of the resin. In practice, a suitable catalyst consists essentially of methylethylketone peroxide and is available from the Norac Company, Azusa, California.
After injection, the polyester resin within cavity 18 is allowed to partially cure for about 10-12 minutes, a~er which clamps 14 are released and male part 12 is removed. After another 8-10 minutes, the resin is sufficiently cured so that baseB
can be separated from female part 10. Base B is then removed from female part 10and allowed to stand for about 24 hours to effect complete curing, whereupon it appears generally as illustrated in FIGURE 2. Generally, a base about 1/4" to about 3/8" thick is desirable.
It will be seen that base B includes a substantially planar floor 22 of rectangular configuration, substantially planar front, and side walls 24, 26, and 28, respectively, each upstanding from floor 22, and a sloping rear wall 30 upstanding from floor 22 and integral with side walls 26 and 28. A peripheral flange 34 extends from upper edges of front wall 24, side walls 26 and 28, and rear wall 30, with the portions of peripheral flange 34 adjacent side walls 26 and 28, and rear wall 30 having a peripheral rib therein.
After curing, flash on the edge of peripheral flange 34 is trimmed off. A foam injection port 37 is drilled through sloping rear wall 30 for injection of a self-foaming resin in the in si~u foaming process described hereinafter. Also, a plurality of 1/16"
vent apertures 39 are drilled through floor 22, front wall 24, and along peripheral rib 36.
As an alternative to a resin injection process, base B can be manufactured as a vacuum molded shell from materials such as acrylonitrile-butadienestyrPne (ABS) or polyvinylchloride (PVC).
Referring to FIGURE 3, a composite, flexible polymeric skin S (shown in FIGURE 4) is formed on the surfaces of form 40. Specifically, form 40 includes abase 42 having a substantially planar, peripheral surface 42a. A member 44 having a configuration equaling that of the desired inner surface of the bathtub projects from base42 and includes a floor surface44a generally complimentary to floor22 of base B, a front wall surface 44b generally complimentary to front wall 24 of base B, a pair of side wall surfaces 44c and 44d generally complimentary to side walls 26 and 28 of base B, and a sloping rear wall surface 44e generally complimentary to rear wall30 of baseB. Protruding from floor surface44a is projection44f that is ICP~P.DOC

2100~18 positioned at the desired location of the drain of the bathtub. As seen in FIGURE 3, recess 46 is provided in base 42 surrounding member 44, wherein the arms of the bathtub are cast. Recess 46 includes a bottom floor portion 46a, and an outer upright wall portion 46b, located intermediate between bottom floor portion 46a and peripheral surface 42a. Base 42 includes an upright wall portions 46c extending in a direction opposite member 44 from the peripheral edge of surface 42a. Positioned at a plurality of locations on upright wall portions 46c are hooks 47 for securing form 40 to a frame for a base described below in more detail.
Preparatory to fabrication of the composite, flexible polymeric skin, peripheralsurface 42a and all surfaces of member 44 and recess 46 are first cleaned with a clean cloth and a solvent such as methylethylketone. Cleaning should remove all contaminants and any residual process materials. Af~er the surfaces are cleaned, it is preferred that they be shined to a high gloss using a wax such as one designated as "Partall No. 2", available from Rexco Chemical Corp., Carpenteria, California. It is also preferred that prior to waxing that the surfaces be preheated to a temperature of 75F +10. The resulting waxed surfaces should have a uniform high gloss with nostreaks or marks visible. The surfaces should be cleaned after each use and waxed at least during every other cycle.
After the surfaces have been cleaned, waxed, and heated, a mold release agent, such as polyvinyl alcohol, available commercially under the trade name "Partall PVA
No. 10" from Rexco Chemical Corp. is applied by first spraying on a thin dust coat and then applying a second wet coat. The resulting coating should be shiny and bubble-free.
Referring to FIGURE4, composite polymeric skin S is formed by the following steps. In the first step, a first coating U1 of an elastomeric resin, preferably an elastomeric urethane, is formed on the surfaces of form 40 by spraying two layers of elastomeric resin onto the surfaces of the form. The first layer is applied by spraying onto the surfaces a mixture of an elastomeric resin, a volatile carrier solvent, and a catalyst. Prior to the application of the first layer, the mold is conditioned by wetting the entire mold with a solvent, such as methylethylketone. Prior to application of the elastomeric resin of the first layer, the surfaces of the mold should be allowed to completely dry, and there should be no drip spots. As described above, a second layer of an elastomeric resin, preferably an elastomeric urethane, is applied to the first layer. The second layer is formed by spraying the first layer with a mixture of the elastomeric resin, a wetting agent, a volatile carrier solvent, and a catalyst. If desirable, color additives may be added to the second layer of first coating U1. Color I~Pa68~AP.DOC

2100~1~
additives can also be added to the first layer but it is preferable to only add them to the second layer. In this manner, the first layer adds a deep lustre to the surface. In the second step, a second coating U2, comprising an elastomeric resin, preferably an elastomeric urethane, is formed on the first coatingU1 by spraying onto the first 5 coating Ul a mixture of an elastomeric resin and a catalyst. Second coating U2 is the predominant material in the composite polymeric skin and imparts thickness and strength theFeto. The thickness of coating U2 can be varied to add stif~ess and strength to different areas of the fabricated article. The skin at this stage can be used as is; however, if more "body," i.e., a soft feel to the skin is desired, preferably a third 10 coating U3 can be applied. Third coating U3 comprises a foamable resin, preferably a foamable urethane. Coating U3 is formed on the surfaces of U2 by spraying onto the surfaces of U2 a mixture of the foamable resin and a catalyst. Coating U3 does not contribute greatly to the strength of composite skin S but adds a "soft feel" to the composite skin. While composite skins can be provided without layer U3, where the 15 "soft feel" is desired, it is preferred to apply coating U3.
A preferred elastomeric urethane for coating U1 is sold under the designation "Chemglaze V021" and is available from Lord Corporation, Erie, Pennsylvania. Theelastomeric urethane is diluted with a solvent such as one sold under the designation "Chemglæe 9951" by Lord Corporation, in a ratio of approximately 6 to 6.25 parts20 elastomeric urethane to about I part solvent by volume. A preferred catalyst for use in the first step is sold under the designation "Chemglaze 9995" and "Chemglaze 9992" by Lord Corporation. The catalyst is used in a ratio of approximately 37.5parts elastomeric urethane to one part Chemglaze 9995 and one-half the amount ofChemglaze 9992. A preferred wetting agent for use in the first step is sold under the 25 designation "Chemglaze 9971" by Lord Corporation, and is used in a ratio of approximately 20.8 parts elastomeric urethane to one part wetting agent by volume.
When the preferred catalysts are used, the 9995 catalyst should be added first, followed by rnixing thoroughly for one minute, and then the 9992 catalyst should be added followed by mixing an additional minute. The foregoing preferred composition 30 represents a 4.9% by weight catalyst mixture based on the elastomeric urethane component only. Other catalyst levels may be used depending on the resin system employed and the atnbient conditions. The foregoing rnixture can be applied ontoform40 with a conventional air-assisted spray gun or a siphon-type spray gun.
Preferably, the elastomeric urethane mixture of the first layer of first coat U1 is 35 sprayed onto the form 40 in a first thin coat followed by a second coat. The resulting first layer is preferably about 1 ts 2 mils thick. The applied coating should be ICP~P.DOC
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2100~8 substantially free of dirt, gas bubbles, or other foreign materials that would render the finished product defective. The finished coating should be of uniform thickness and free of runs or drips that would be visible on the exposed surface. Depending upon the loss of thickness as the solvent evaporates, the initial application of the first layer 5 may need to be thicker than I to 2 mils. After application of the first layer, the volatiles are allowed to evaporate. An electric heater and a fan (not shown) can be placed under form 40 and actuated to raise the temperature of form 40 to accelerate curing of the first layer.
As described above, the first layer preferably does not include any color 10 pigments to help conserve on the amount of pigments used. As described below in more detail, second layer of first coat U1 can include color pigments to provide the needed aesthetic appearance.
An elastomeric resin, preferably an elastomeric urethane, is sprayed onto the surface of the first layer to complete first coat U1. The purpose of this second layer is 15 to form a color layer that includes urethane that is pigmented to a desired color.
Although the first layer of elastomeric urethane could be pigmented, it is preferred that the second layer be pigmented in order to conserve the amount of pigmented urethane required.
A preferred elastomeric urethane for use in the second step is sold under the 20 designation "Chemglaze V021" by Lord Corporation. Lord Corporation also provides a wide selection of elastomeric urethanes that include color components.
These elastomeric urethanes are also sold under the Chemglaze V designation and can be combined with Chemglaze V021 in approximately equal amounts to provide the elastomeric urethane components of the second layer. The solvent, wetting agent,25 and catalyst used in the second layer are identical to those used in the first layer and are used in approximately equal amounts and should be mixed in the same manner.
The mixture for the second layer can be sprayed onto the first layer with a conventional air-assisted spray gun or a siphon-type spray gun. Preferably, the elastomeric mixture is sprayed onto the first layer in an amount that will result in a 30 second layer having a thickness of approximately 4 mils ~1 mil. AP~er the mixture is applied, the solvent is allowed to evaporate. As described above, this evaporation can be accelerated by elevating the temperature of the form. The resulting second layer should be free of dirt, gas bubbles, or other foreign materials that would render the finished product defective. The finished layer should be free of runs and drips that 35 would be visible on the finished part. The layer should be allowed to cure completely before further processing, and preferably has a thickness that is approximately 4 mils lCP~P.WC

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2100~18 +l mil thick. When first coat Ul is provided using the urethanes described above, processing times of about I to about 2 hours are achievable, by comparison, providing a coating using vinyl resins can involve process times that are two to three times longer. Processing times less than about 1 to 2 hours may also be achieved when urethane resins available without volatile carriers are employed. Such type of carrier-free resins are also known as " 100% solids" resins.
Subsequent to the application of first coat Ul of elastomeric urethanes, as described above, a second coat U2 of an elastomeric resin, preferably an elastomeric urethane is applied to coat U1. A preferred elastomeric urethane for use in the second step is sold under the designation "Chemglaze M331" by Lord Corporation. The elastomeric urethane is mixed with a catalyst sold under the designation "Chemglaze M402" by Lord Corporation. The elastomeric urethane is mixed with the catalyst in a ratio of approximately 3 to about 1 by volume. The mixture is applied under conditions that result in a coating that is approximately 55 to 80 mils thick. Such a coating can be accomplished by applying the mixture to the heated mold carrying first coatingUl. Preferably, for the elastomeric urethane described above, the mold temperature is approximately 85F and the elastomeric urethane mixture is heated, but not such that it exceeds 105F when exiting the applicator. Suitable results have been achieved when four or more thin coats of approximately 15 to 20 mils each are applied to avoid running. Approximately 5 minutes between coatings is preferred,although shorter or longer periods of times may be used if greater or fewer passes are employed. A~er the last coating has been applied, the entire coating should be allowed to firm up and become integral. Typically, this can take approximately 45 minutes. Curing times can be shortened using an infrared oven; however, the coating should be allowed to cure at ambient conditions for approximately 10 minutes or longer before oven curing. Curing will be complete when the solvent ceases to volatilize. The ~esulting coating is a coating of an elastomeric urethane approximately 55 to 80 mils thick. The coating should be free of dirt, lumps, or other foreignmaterials that would render the finished product defective. The finished coatingshould be smooth and shiny, of uniform thickness, and free of runs or drips that would be visible on the finished part. Proper curing of the skin can be tested by taking a cross section of the skin. A properly cured skin should not be able to be torn apart using normal strength. If such tear test is to be employed, it should be performed on the center most portion of a cut edge.
Subsequent to the formation of second elastomeric resin coat U2, an optional coat U3 of foamable resin, preferably a foamable urethane, is sprayed onto the surface lCP~P.WC

-lo-21~0~18 of coat U2. A preferred foamable urethane for use in this step is sold under thede.signation "IPI 0469A and B Spray Urethane Foam" by IPI, Elkton, Maryland. TheIPI 0469A and B Spray Urethane Foam has about a 3.5 to about 5 Ib. density. The preferred formulation includes a volume ratio of three parts IPI 0469B to one part 5 IPI 0469A The preferred urethane used in foamable urethane coatingU3 differs from the preferred elastomeric urethanes described above for coatings Ul and U2.Elastomeric urethanes are incapable of foaming, while foamable resins for coating U3 are considered self-foaming which, when sprayed or applied to a surface, will foam to provide a cellular matrix.
10When applied, it is preferred to achieve a thickness of coating U3 of approximately 1/8 to approximately 1/4 of an inch. Suitable thicknesses can be achieved by applying the foamable urethane mixture to coating U2 using a spray gun.
The mold temperature should be at least about 85F and not more than about 120F.
The temperature of the foamable urethane mixture upon exit of the spray gun should 15not exceed about 140 to about 160F. The coating should be applied as smooth as possible without runs. Surface temperature of the foam skin should be about 85-95F when taken along the bathtub arms. Before further processing, the applied foam should be allowed to become integral which can take approximately five minutes.
Longer foaming times may be required to achieve the required skin temperature 20 Typically, foaming polyurethane resins generate and maintain heat when they foam.
~ccordingly, a measurement of the skin temperature is an indication of the completeness of the foaming. The resulting foamed layer should be of uniform thickness, except on the wall of the tub where the plumbing will be located, where a thinner skin layer is desired. The coating should be free of drips that would be visible 25 on the finished part. When applied, the finished foam should cover the entire part with a foam layer approximately 1/4 inch thick at the maximum. No areas of the mold surfaces should be void of the foam layer, except where the plumbing wall as described above that is deliberately "skinned" rather than foamed. The purpose of the preferred foamable pol~,urethane coatU3 is to form a firmer polymeric skin S by 30 adding body to the underlying elastomeric resin coats Ul and U2. In applications where the body of the composite skin S comprising coatings Ul and U2 is satisfactory, coating U3 may be unnecessary. On the other hand, when the enhanced "body" is desired, coating U3 is preferred.
When the foamable resin coatU3 is applied to the plumbing wall, it is 35 purposefully made thinner than the thickness of other portions of coat U3 in order to ensure that space is provided for the foamable resin F described below in more detail ICP~P.DOC
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Although the foamable urethane layer U3 is formed from a self-foaming polyurethane resin, when sprayed on in a thin layer, the resin does not generate and retain sufficient healt to induce substantial foaming. Consequently, a thin layer of a foamable polyurethane resin cures to form a flexible polymeric layer that has numerous 5 micropores that are readily visible under low magnification. The term "skin foam"
(also commonly referred to as an "integral skin foam") refers to a foaming resin that forms an integral adherent skin against surfaces with which the resin is in contact during curing. Such resins include a surfactant that causes resin to wet the surface and cause the "skin" to form against the surface as a resin foams and cures.
Polyurethanes are preferred because they set up relatively quickly compared to other resins such as vinyl resins. The shorter curing times results in shorter process times which leads to a more economical manufacturing process. The polyurethanes,as noted above, cure in a matter of minutes which is particularly advantageous when one is manufacturing on a commercial scale. The elastomeric urethane polymers are also preferred to other polymers such as vinyl polymers because of their enhanced physical properties, such as tensile strength, elongation, abrasion resistance, that make them more suitable to withstand the rigors of actual use than other polymers such as vinyl polymers. In addition, urethane polymers do not lose plasticizer and become brittle over time as has been observed with vinyl polymers.
In the next step of the fabrication process, baseB is inverted, secured to frarne 50 and placed over and secured to form 40, resulting in a cavity 70 between base B and form 40 into which a conventional self-foaming polyurethane resin may be injected and allowed to expand and cure to create a cellular foam in cavity 70.
With reference to FIGURES 4 and 5, frame 50 is seen to comprise a steel framework, the interior dimensions of which generally conform with the exterior dimensions of base B. Frame 50 has a generally rectangular frame base 52 having a lower surface 53 generally complementary to peripheral surface 42a of forrn 40 and flange 34 of base B. Lower surface 53 is sealed to planar peripheral surface 42a of form 40 and peripheral flange 34 of base B as described below in more detail. Spaced around the periphery of base 52 are a plurality of holes 69 passing through lower surface 53. Frame 50 further includes upright frame members 54 complementary with sidewalls 26 and 28 of base B, angle frame members 56 complementary with rear wall 30 of base B, and upright end members 58 complementary with front wall 24 of base B. Additionally, a rectangular array of cross-top frame members 60 spans the floor portion22 of baseB. A manually operated closure device62 is mounted ICP~P.DOC

between angled frame members 56 for sealing port 37 upon completion of the foam injection process described below.
Referring to FIGURE5, baseB is assembled with frame50 by inverting baseB as shown in FIGURE4 and lowering frame50 over baseB until bottom surface 53 of rectangular base 52 is sealed to the underside of peripheral flange 34 as described below. Bottom surface 53 of rectangular base 52 is defined by planar metal gasket 150 that cooperates with an integral silicone rubber seal 152 to seal rectangular base 52 to the underside of peripheral flange 34 and planar peripheral surface 42a of form 40. Integral silicone rubber seal 152 has a body 154 that is shaped to be complementary with the channel in the underside of flange 34. Body portion 154 of integral silicone rubber seal 152 extends around the periphery of base B within the channel in peripheral flange34. Integral silicone rubber seal 152 also includes a peripheral flange 156 that extends outwardly from body 154 so as to extend the seal between peripheral surface 42a and metal gasket 150. Before frame 50 is lowered over baseB, integral silicone rubber seal 152 is positioned within the channel in the underside of flange 34 and around base B. Overlying integral silicone rubber seal 152 is a planar mounting plate 158 that covers the entire exposed upper surface of integral silicone rubber seal 152 and separates it from metal gasket 150. With integral silicone rubber seal 152, metal gasket 150, and mounting plate 158 in place, frame 50 is lowered over baseB until metal gasket 150 engages upper surface of mounting plate 158. In this manner, base B is sealed to frame 50 to prevent leakage of foam during the in si~u foaming step described below. Base B is held firmly in place against frame 50 by screws 67 located through holes 69 in frame 50, and holes (not shown) in metal gasket 150, body 154 of silicone rubber seal 152 and base B. Screws 67 aresecured by speed nuts 66.
The assembled baseB and frameS0 are then lowered onto form40, with member44 projecting into the interior of baseB, until the underside of integral silicone rubber seal 152 conformably abuts planar peripheral surface 42a. As theunderside of integral silicone rubber seal 152 abuts surface 42a, frame 50 is sealed to base 42 of form 40 and thereby prevents leakage of foam resin from cavity 70 during the in si1u foaming step described below. Base 42 of form 40 and frame 50 are then secured together using hooks 47 on form 40 and clamps 160 provided on frame 50.
At this point, it will be noted (FIGURE S) that base B is separated from composite polymeric skin S to define therebetween a cavity 70.
Referring additionally to FIGURE 6, cavity 70 is then filled with a flexible cellular foam F by in si~u foaming process. Preferably, cellular foam F comprises a ICP~P.DOC

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flexible polyurethane foam material, such as the one available under the designation of IPI 1156A and B urethane foam from IPI, Elkton, Maryland. IPI 1156A and B
urethane foam has a density of about 3.5 to about 5 Ibs. The A and B components are mixed in a ratio of one part A to 1.45 parts B by volume and are mixed in a conventional plural component system available from Witco Chemical, Wilmington, Delaware. It is preferred that a 1 inch foam core be provided, accordingly, the spacing between baseB and composite polymeric skinS should be approximately I inch The urethane foam resin mixture is injected under force in liquid form through port 37, with the foam thereafter expanding as is conventional throughout cavity 70 and with trapped air escaping through vent apertures39. Port37 is closed with closure device 62 after injection of the liquid to contain the expanding foam. During expansion and subsequent curing, foam F bonds to the interior surfaces of base B and to the interior surface of foamable polyurethane coat U3 of skin S. Preferably, the surface of foamable urethane coat U3 is about 70 to 80F and the temperature ofbase B is between 70F and 80F for the foam described above. The temperature ofthe foamable polyurethane should be in accordance with the manufacturerls specifications, with about 73F to about 77F being suitable for the resins described above. After injection of the foamable polyurethane, sufficient time should be provided for completion of the curing period. Generally, waiting periods of about 20 minutes are suitable for the resins described above. The resulting foamed layer should be free of voids and should bond securely to the fiberglass shell and thepolymeric skin. Foam leaks around the integral silicon rubber seal should be avoided.
While specific polyurethane foam materials have been described above, it sh~uld be understood that other open and close cell foams may also be employed.
The amount of foam F used as well as the output rate of the dispensing unit are critical to obtaining a final product having optimum texture and strength. In practice, it is found that an overpack of 30% to 40% achieves superior results, with 35% being used preferably for optimum results. By overpack it is meant that morefoam by weight is injected into cavity 70 then would be required to just fill cavity 70 with foam upon complete curing. If an insufficient overpack of foam is used, there is a likelihood that the foam will not be distributed evenly throughout the cavity 70, resulting in large void spaces within cavity 70. If too much foam is used, the cured foam often displays shrinkage, with consequent deformation of the bathtub surfaces.
A~er curing (a process that takes about 20 minutes), clamps 160 are released and the assembled bathtub comprising baseB, composite skinS, and foamF sandwiched therebetween, together with frame 50, is removed from form 40, with skin ~cP~P~wc 2 1 ~ 8 separating from the surfaces of recess 46, member 44 and surface 42a of forrn 40Thereafter, screws 67 are removed and frame 50 is separated from the bathtub. Inorder to facilitate release of form 40, compressed air can be injected into the mold until separation is accomplished. The resulting bathtub should then be washed with 5 water to remove polyvinyl alcohol.
The finished bathtub then appears as seen in FIGURES 7 and 8 as comprising a center receptacle portion 80 and an outer, laminated peripheral arm flange 82, the upper surfaces which are covered by the composite skin S, and the lower surfaces of which in large part are formed by base B, with foam F being sandwiched therebetween 10 at substantially all points. It will be noted that projection 44f on member 44 (FIGURE 3) has resulted in an opening 84 in the bottom of the bathtub, which opening is closed by the skin S and base B, both of which must be removed by drilling or otherwise to form a drain for the bathtub. An overflow outlet 86 is formed on the front wall of the bathtub in a similar manner.
The bathtub as illustrated in FIGURES 7 and 8 may be installed as it is by lowering the bathtub into a suitable framework, whereupon the bathtub either rests on the floor or is supported by flange 82, or both. Alternatively, the bathtub may be freestanding, merely resting on the floor and with its exposed sides being covered by appropriate facia, not illustrated, one end of which can be inserted into a recess 85 20 provided by the underside of rib 36 of base B in the lower surface of flange 82. As yet, another example, the bathtub may be inserted into an enclosure form by one to three walls, with a framework depending from those walls in supporting the flange 82, and with the exposed side or sides of the bathtub being covered by appropriate facia.
Alternatively, referring to FIGURES 4 and 9, a receptacle for fluid formed in 25 accordance with the present invention includes polymeric skin coatings U1 and U2 of polyurethane as described above, and coating U3 comprising a foamable polymeric resin that is approximately 1 to 11/2 inches thick. Coating U3 is coated with a binder coat 100 that promotes binding of the resin of U3 to fiberglass layer 102 that is applied over binder coat 100. In accordance with this aspect of the present invention, 30 coatings Ul, U2 and U3 are provided on a form similar to form 40 described above.
Foamable polymeric resin coating U3 generally is thicker in this embodiment than in the embodiment described above. Such thicknesses can be achieved by applying multiple layers of the polymeric resin in the manner similar to the manner coating U3 is described as being applied above. Binder coat 100 is preferably a urethane-35 polyester mixture, such as the one designated M5 hybrid available from PolymerDevelopment Laboratory, Orange, California. Binder coat 100 can be applied by ~cP~P~wc 210~18 ~
rolling or brushing and is generally applied to a thickness of about 5 to about 10 mils.
After binder coat 100 is applied, layer of fiberglass 102 can be applied by conventional techniques that involve spraying. Preferably, layer of fiberglass 102 is al)plied to a thickness of approximately 1/4 to 5/16 inches. After the fiberglass cures, the entire 5 lay-up can be removed from the form to provide a receptacle for fluid in accordance with the present invention As indicated above, it should be understood that cushioned receptacles for fluid formed in accordance with the present invention can take other forms besides bathtubs. Suitable applications include shower stalls, sinks, and hot tubs.
While the invention has been described with reference to a preferred embodiment, it is to be clearly understood by those skilled in the art that the invention is not limited thereto, but rather that the scope of the invention is to be interpreted only in conjunction with the appended claims. For example, the specific temperatures and processing times may vary depending on the particular resin being employed and 15 the ambient conditions.

IcPra~4AP.WC

Claims (26)

1. A method for fabricating a cushioned receptacle for fluid comprising the steps:
fabricating a base having a shape that is generally similar to the shape of the receptacle;
fabricating a flexible composite skin by:
(a) applying a first coat of a urethane polymer onto a form having a shape complementary to the receptacle;
(b) applying a second coat of a urethane polymer onto the first coat;
mating the base with the form to provide a cavity between the base and the second coat of urethane polymer; and filling the cavity with a foamable polymeric resin.

2. The method of Claim 1, further comprising before the step of applying the first coat:
applying polyvinyl alcohol to the form; and conditioning the form by applying a solvent selected from the group consisting of methylethylketone and acetone.

3. The method of Claim 1, wherein the first coat comprises a first layer of an elastomeric urethane and a second layer of an elastomeric urethane that includes a color additive.

4. The method of Claim 3, wherein the elastomeric urethane of the first layer is applied by spraying about 1 to about 2 mils of the elastomeric urethane onto the form and the second layer of elastomeric urethane is applied by spraying about 3 to about 5 mils of the elastomeric urethane and color additive onto the first layer.

5. The method of Claim 1, wherein the urethane polymer of the second coat is an elastomeric urethane.

6. The method of Claim 5, wherein the elastomeric urethane of the second coat is applied by spraying about 55 to about 80 mils of the elastomeric urethane onto the first coat.

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7. The method of Claim 1, wherein a foamable polymeric resin is applied to the second coat of a urethane polymer before the mating steps.

8. The method of Claim 7, wherein the foamable polymeric resin applied to the second coat is a foamable urethane.

9. The method of Claim 8, wherein the foamable urethane is applied by spraying a coating about 0.125 to about 0.25 inches thick onto the second coat.

10. The method of Claim 1, wherein the foamable polymeric resin of the filling step is a foamable urethane.

11. The method of Claim 10, wherein the cavity defined between the base and the foamable polymeric resin is about 1.0 inch wide.

12. The method of Claim 1, wherein the base is supported by a frame that is sealed to the base by an integral silicone rubber seal, the integral rubber seal also sealing the frame to the form.

13. The method of Claim 1, wherein the base is formed from a polyester resin filled with a fire retarding agent.

14. A cushioned receptacle for fluid comprising:
a base;
a first coat of an elastomeric urethane;
a second coat of an elastomeric urethane applied to the first coat; and a layer of a foamed resin between the base and the second coat of elastomeric urethane.

15. The receptacle of Claim 14, wherein the first coat of elastomeric urethane further comprises a first layer opposite the base substantially free of color additives and a second layer adjacent the second coat that includes a color additive.

16. The receptacle of Claim 14, wherein the first layer is about 1 to about 2 mils thick and the second layer is about 3.0 to about 5.0 mils thick.

17. The receptacle of Claim 14, wherein the second coat is about 50 to about 80 mils thick.

18. The receptacle of any one of Claims 14 to 17, further comprising a third cast of a foamable urethane applied to the second coat.

19. The receptacle of Claim 18, wherein the third coat of the foamable urethane is about 0.125 to about 0.25 inches thick.

20. The receptacle of any one of Claims 14 to 19, wherein the foamed resin is a foamed polyurethane.

21. The receptacle of any one of Claims 14 to 19, wherein the base comprises a reinforced polyester resin.

22. The receptacle of any one of Claims 14 to 21, wherein the base further comprises a fire retarding agent.

23. The receptacle of any one of Claims 14 to 22, wherein the base comprises:
a wall portion;
a floor portion; and a peripheral flange portion, the wall portion being closed at one end by the floor portion and open at the opposite end, the peripheral flange portion extending from the open end of the wall portion, the peripheral flange including a seat for receiving an elastomeric seal for sealing the coat of the foamable urethane to the base.

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24. A method for fabricating a cushioned receptacle for fluid comprising the steps:
fabricating a flexible composite skin by (a) applying a first coat of urethane polymer onto a form having a shape complementary to the receptacle;
(b) applying a second coat of a urethane polymer onto the first coat;
(c) applying a foamable polymeric resin onto the second coat;
applying a binder coat onto the foamable polymeric resin; and applying a coating of fiberglass onto the binder coat.

25. A method for fabricating a cushioned receptacle for fluid comprising, fabricating a base, the base having a wall portion, a floor portion and a peripheral flange portion, the wall portion being closed at one end by the floor portion and being opened at an opposite end, and the peripheral flange portion being integral with and extending from the open end of the wall portion;
fabricating a composite flexible polymeric skin by:
applying a first coat of elastomeric urethane to a form by spraying a liquid mixture of an elastomeric urethane and a volatile carrier therefor on the form to provide a first layer of the elastomeric urethane, the form having a peripheral surface, a recess and a member having a wall surface and a floor surface, the member centrally projecting from the peripheral surface, the wall surface of the member being generally complementary to the wall portion of the base, the floor portion of the member being generally complementary to the floor portion of the base, the recess surrounding the wall surface of the member and joining the wall surface and the peripheral surface, the recess being generally complementary to the peripheral flange portion of the base, allowing the first layer of elastomeric urethane to become tack-free, completing the first coat by spraying a liquid mixture of an elastomeric urethane and a volatile carrier therefor onto the first layer to provide a second layer of the elastomeric urethane, and allowing the second layer of elastomeric urethane to become tack-free;
spraying an elastomeric urethane on the first coat to provide a second coat, the elastomeric urethane of the second coat being applied to the first coat on all of the surfaces of the form;
spraying a foamable urethane onto the second coat to provide a third coat;
assembling the base with a frame having a peripheral frame base, the frame base having a lower surface generally similar in configuration to the peripheral surface of the form and having a supporting framework generally similar in its interior configuration to the outer configurations of the wall portion and the floor portion of the base, by inserting the wall portion and the floor portion of the base into the supporting framework of the frame and securing the base to the frame;
assembling the frame with the form so that the base is separated from, but closely adjacent to the composite flexible polymeric skin to define a cavity;
injecting a foamable polymeric resin in liquid form into the cavity and allowing the foamable polymeric resin to expand throughout the cavity to thereby form a flexible foam between the base and the flexible composite polymeric skin; and disassembling the skin from the form and disassembling the frame from the base.

26. A cushioned receptacle for fluid comprising;

a first coat of an elastomeric urethane;
a second coat of an elastomeric urethane applied to the first coat;
a third coat of a foamable urethane applied to the second coat;
a binder coat applied to the third coat; and a layer of fiberglass applied to the binder coat.