Loading patent…
AssigneeNone recorded
InventorsPETER JOHN STEPHENSON, TIMOTHY MARTIN TICKNER
Estimating the term…
Thin walled elastomeric articles are made by electrostatically depositing a coating of an elastomeric composition on a rigid shape former (24), consolidating the coating and then stripping the article (30) from the former. Gloves and condoms are among the articles which can be made in this way.
A process for forming a thin-walled article, which process comprises electrostatically spraying charged particles of an elastomeric composition into a chamber containing a rigid shaped former having an “earthed” (as herein defined) conductive surface whereby the charged particles of the composition are attracted to the conductive surface of the former to form a coating of the composition thereon;
A process according to any preceding claim, wherein the thickness of the consolidated coating is from 20 to 200 microns.
A process according to any preceding claim, wherein the thickness of the consolidated coating is from 40 to 100 microns.
A process according to any preceding claim, wherein the thin-walled article is flexible.
A process according to any preceding claim, wherein the thin-walled article is a glove or a condom.
A process according to any preceding claim, wherein the elastomeric composition includes an elastomeric polyurethane;
A process according to any preceding claim, wherein the rigid former is rotated during spraying.
A process according to any preceding claim wherein, after the coating has consolidated but before it has been stripped from the former, electrostatically charged particles of the same or of a different composition are sprayed into the chamber to form an additional coating on the former, and the particles being consolidated to form an additional coating.
Apparatus for forming a thin-walled article, comprising a chamber containing a rigid shaped former having an “earthed” (as herein defined) conductive surface, means for electrostatically spraying charged particles of an elastomer composition within the chamber whereby the particles can be attracted to the conductive surface and can form a coating thereon, and stripping means for stripping the thin-walled article from the shaped former after the coating has been consolidated on the former.
Dependencies are inferred from the claim text.
From the US filing history. Foreign family members aren’t listed.
Backward citations are indexed for grants only.
Drawings are temporarily unavailable. Open the PDF at USPTO
Shaping by coating a mould, core or other substrate, i.e. by depositing material and stripping-off the shaped article; Apparatus therefor: using…
Use of unspecified rubbers as moulding material
Outerwear: gloves
Medical equipment; Accessories therefor: condoms
Term end not estimated
USPTO file history isn’t available for this patent, so only indexed dates are shown.
This invention relates to a process and apparatus for making thin-walled elastomeric articles.
Conventional processes for making thin-walled rubber articles, such as gloves, involve dipping a shaped former into a rubber latex, or other suitable dipping medium, to coat the former with the latex, or other medium, and curing or drying the rubber latex on the former to produce a thin-walled article, then stripping the finished article from the former. This so-called dipping process has become highly developed so that it is now possible reliably to produce very thin-walled articles such as condoms and surgeons' gloves of extremely high quality. There have been proposals to make thin-walled elastomeric articles by other methods, such as by spraying the rubber latex (or the like) on to the former (instead of dipping) but it has not proved possible to produce such high quality products reliably in these ways and these processes are rarely used.
It is known to form a protective coating on a surface by electrostatic deposition of a coating composition thereon, and this process has been extremely successful, for example, in painting irregularly shaped objects. In U.S. Pat. No. 3,698,847, the electrostatic deposition process is unusually used to form a generally non-elastomeric hollow article by electrostatically depositing a synthetic thermoplastic resin on a collapsible former, and then withdrawing the collapsed former through a hole in the wall of the self-supporting hollow article so formed. The process is described for use for making Christmas tree ornaments.
Reference is now made to the accompanying drawing, in which:
FIG. 1 is an orthogonal view of part of an apparatus according to the invention; and
FIG. 2 is an orthogonal view of another part of an apparatus according to the invention.
In the drawings, an apparatus for forming a thin-walled article comprises a housing 10 defining a chamber 12 therein. The housing 10 contains an electrostatic spray head 14, which is connected to a supply 16 of a liquid solidifiable composition via a pipe 18. A pump 20 is provided to pump the composition from the supply 16 to the spray head 14. The spray head 14, the pipe 18, the supply 16 and the pump 20 may be entirely conventional. The pump 20 and the supply 16 are disposed outside the chamber 12.
A conveyor 22 is provided with a plurality of shaped formers 24 thereon. Each of the shaped formers 24 has a conductive surface and is earthed via the conveyor 22. A heating means 26 is provided for each shaped former 24. The heating means 26 comprises electrical circuitry necessary to heat the former 24 by inducing electrical currents in the former 24. Heating the former serves to dry the composition thereon to produce a thin-walled article 30 having the same shape as the exterior surface of the former 24.
The conveyor 22 extends through the chamber 14 and through a stripper 28. The stripper 28 serves to strip the thin-walled article 30 from the shaped former 24.