Process for coating foam

Details Process for coating foam Process for coating foam

1999-07-21

2002-06-18

Copenheaver, Blaine (Department: 1771)

Stock material or miscellaneous articles

Web or sheet containing structurally defined element or...

Composite having voids in a component

C428S308400, C427S421100, C427S407100, C427S412100

Reexamination Certificate

active

06406780

ABSTRACT:

This application claims priority from PCT/AU97/00798 filed on Nov. 24, 1997 which claims priority from Australian Application No. PO 3794 filed on Nov. 22, 1996.
FIELD OF INVENTION
This invention primarily relates to foams, such as foamed plastics and foamed rubber. In particular, this invention relates to a process and formulations for sealing products, especially foam products. The invention also applies to other substrates (or products) having a degree of porosity.
BACKGROUND TO THE INVENTION
Foamed plastics are porous, very light substances made of various plastics such as epoxide resins, urea resins, polyurethane, polystyrene, polyethylene or polyvinylchloride. Phenolics, silicones and cellulose acetates can also be foamed. In fact, under the right conditions, almost any thermosetting or thermoplastic resin can be converted into a foam. Foamed plastics have a cellular structure and can be divided into foams having a closed cell structure and foams having an open cell structure.
Foams which have a closed cell structure are synthesised by incorporating a blowing agent or a propellant into the plastic which either evaporates or decomposes at the fusion point of the plastic, releasing gas bubbles which are trapped during the gelling of the plastic.
Foams which have an open cell structure are synthesised by incorporating an inert gas into the resin under pressure and then releasing the mixture to the atmosphere and curing the resulting foam.
Foams may either be flexible or rigid and have a wide variety of uses. Rigid or hard foams such as polyethylene are particularly used for thermal insulation, or furniture and building panels, whereas softer foams are used for cushioning materials, all types of padding and sponges.
Foamed rubber is a highly elastic, porous and lightweight rubber. It is made by various methods using natural or synthetic latex which is mixed with various ingredients and converted to foam. The foam rubber can also be molded and vulcanised. Foam rubber contains approximately 85% air and, similar to foamed plastics, can be used for a wide range of consumer goods including padding for furniture, mattresses and pillows.
Inherent in the majority of uses of foamed plastic or rubber (foam) is the fact that the foam is generally required to be covered or sealed in some way, for both functional, hygienic as well as aesthetic reasons.
The covering and sealing of foam mattresses, pillows, cushions and similar products inhibits the build-up of dust and dust mites in such products. This has significant health benefits.
The covering and sealing of such foam products is particularly important in the medical healthcare industry where foam is used for mattresses, pillows, cushions, commodes and operating theatre aids, with plastic or some other covering material, purchased and stitched or made up to cover the foam for the mattresses etc. There have been increasing instances of patients in hospitals and nursing homes catching infections from such foam mattresses, pillows and cushions, due to the fact that the infection had harboured in either the stitched seams of the covering, in cracks, in ridges or indentations in the surface or had actually lodged in the foam itself.
In order to reduce the sites on the covering or foam where the bacteria can be deposited, and to prevent such problems of infection, manufacturers have attempted to provide a plastic coating which will adhere to foam and thus completely seal it. One US manufacturer has attempted to coat foam by dipping the foam in a vat of coating. However, the method is not able to be used on open cell foams, and further, the coating has a tendency to delaminate from the foam.
Various lamination methods have also been tried to clinically seal foam products. For example, GB patent 1 588 941 discloses the sealing of a pad of foam material by a plurality of spray coatings of a flexible-non porous material such as polyvinylchloride (PVC), at least the final coating of which must contain electrically conductive carbon particles.
U.S. Pat. No.4,046,587 (“Guglielmo”) describes a primer composition for laminating a vinyl protective film onto a polyolefinic-containing foam. The process which is described in Guglielmo is directed to the application of the primer to the foam. This application is stated to be simple (and facile) and no special conditions or equipment are specified for the successful use of the primer. Guglielmo states that, following application of the primer, the vinyl coating may be painted on using a solution formulation of polyvinyl coating.
However, the above methods have either resulted in no bonding or inadequate bonding of the laminate to the foam, or a slight initial bonding which later delaminated when the total foam was sealed, resulting in the plastic laminate cover lifting from or falling off the foam.
OBJECTS OF THE INVENTION
Thus, one object of this invention is to provide a process for sealing foam products such that a substantially continuous, seam free, sealed surface can be obtained; and with the foam still maintaining its flexibility and its foam-like characteristics. Another object of this invention is to provide a flexible foam product with a substantially continuous, seam free, sealed surface.
STATEMENT OF INVENTION
Accordingly, a first aspect of the invention provides a process of sealing any foamed rubber product or foamed plastic product, excluding foamed polystyrene, to provide a substantially continuous, flexible, impervious surface, said process including:
(i) applying to a surface of said product a primer of foam-penetrating viscosity, such that the primer penetrates partially into the product, at least partially coating said surface, and
(ii) applying a liquid first polymeric composition onto the primer-treated surface;
wherein the primer and the first polymeric composition are applied by spraying at a pressure of between about 30 psi and 80 psi.
Where used in this specification, the term “psi” is taken to mean “psi (gauge)” rather than “psi (absolute)”.
Preferably, at least one additional layer of a liquid second polymeric composition is also applied to the treated surface.
Preferably, the primer and the first polymeric composition are applied at a pressure of between about 35 psi and 70 psi and, more preferably, at a pressure of about 60 psi. Accordingly, appropriate high pressure spraying equipment is generally required.
The primer and the first copolymer solution are preferably applied so that they penetrate to a depth of between 1 mm and 10 mm beyond the foam surface. The extent (or depth) of penetration will depend on the density of the foam. For instance, penetration in a high density foam will be less than in a low density foam. For very high density foams, the depth of penetration may be less than 1 mm and for very low density foams, it may be greater than 10 mm. This should not affect the effectiveness of the process.
The formulation of the primer may be the same as or, preferably, different from the formulation of the first and/or second polymeric composition.
Preferably, the first polymeric composition, in association with the primer, forms a sealed layer onto which the second polymeric composition may be applied.
Preferably, the primer, the first polymeric composition and the second polymeric composition include an adhesive polymeric resin. The adhesive polymeric resin may include monomer resins, co-polymer resins or both. More preferably, the primer, the first polymeric composition and the second polymeric composition include at least one of the following: chlorinated rubber, rubber based polymeric resins and their derivatives- including synthetics, elastomeric polyurethane, elastomeric acrylics and their derivatives including styrene acrylic, silicone and silicone derived resins and vinyl resins.
Still more preferably, the primer, the first polymeric composition and the second polymeric composition include a co-polymerised polyvinylchloride (PVC) composition.
Most preferably, the primer, the first polymeric composition and the second polymeric composition include a polyvinyl

Affiliated with

Also associated with

Rating

Process for coating foam does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Process for coating foam, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Process for coating foam will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-2956397