LATEX GLOVES AND ARTICLES WITH
GEOMETRICALLY DEFINED SURFACE
TEXTURE PROVIDING ENHANCED GRIP
AND METHOD FOR IN-LINE PROCESSING
FIELD OF THE INVENTION
The invention relates to synthetic or natural latex gloves and articles having enhanced gripping characteristics provided by virtue of a roughened, geometrically defined, surface integrally formed on the outer surface of the glove during its in-line manufacturing process.
BACKGROUND OF THE INVENTION
Synthetic or natural latex gloves providing enhanced gripping characteristics are known to be extremely desirable, since they provide slip-resisting, gripping action, even when wet articles are handled. The external surface of the glove can be textured in order to obtain superior gripping properties. Traditional approaches include the use of textured formers, which are dipped into an aqueous latex emulsion resulting in a textured glove surface at the textured former contact surface. When the glove is inverted, the external glove surface becomes textured with a pattern representative of that on the former. Generally, the former external surface can be textured or indented in each of the finger, thumb tips, and body portions so that gloves with texture in these regions can be produced. The details of the texture produced can vary according to the requirements of the glove manufacturer. Unfortunately, this simple approach has limited applications, since dipping defects occur at the edges defining the texture, resulting in a latex film, which has holes or which tears easily at these defective regions. The textured former surface also readily degrades, and latex articles are difficult to strip from the former after crosslinking of the latex film, due to the texture present at the former-latex interface. The stripping action can tear formed latex articles or, in the worst case, produce pinholes and other defects, which may be difficult to observe but nevertheless deteriorate the overall quality and reliability of the latex product. For example, U.S. Pat. No. 6,081,928 and IntT Pat. App. Pub. No. WO 00/19847 to Bourne disclose an elastomeric glove with enhanced grip strength. The gripping surfaces of the glove, preferably each of the finger and thumb tips and the body portions are molded with a plurality of concave indentations between 0.004 and 0.020 inches or with a plurality of suction cups with a circular border diameter ranging from 0.008 to 0.5 inches. The manufacturing process employs glove-dipping formers having surfaces comprised of a plurality of convex protrusions or suction cup structures. In another example, U.S. Pat. No. 6,254,947 to Schaller discloses flexible plastic articles bearing polymeric slip coatings and having raised/recessed roughness on their surfaces. This slip coating is comprised of a polymeric material and, at least in sections, has repeating shape deviations of the surface that are recessed in relation to a raised, net-like structure. The slip coating is applied to the interior surface of the glove—not the exterior surface of the glove—and provides slipperiness, not roughness with improved grip, since the soft slip coating material comprises polyacrylates and/or polymethacrylates and/or polysiloxanes over natural rubber. The glove is made by dipping a porcelain former with a series of indentations, and the contacted surface becomes the external surface having protrusions, while the non-contact surface with recesses
becomes the skin-contact surface and receives the soft polymeric coating. In a third example, U.S. Pat. No. 5,098, 755 to Tanquary et al. discloses textured thermoplastic elastomeric film, articles comprising the same, and a method
5 of making such a film and articles. Textured and embossed films for condom articles are provided with an embossed pattern with 1,000 to 100,000 embossments per square inch of embossed surface. Dipping a latex article does not form this texture, but the embossed pattern is formed by elevated
10 heat and/or pressure-forming conditions. Heating of latex to produce an embossed pattern generally degrades its mechanical and barrier properties.
Another approach is to produce a rough gripping surface of a glove by foaming the latex external surface. Incorpo
15 rating air into the aqueous latex produces this foamed surface. Air bubbles in latex generally are spherical in shape with non-uniform bubble sizes, due to the inherent instability resulting from larger bubbles growing when they contact smaller bubbles. When air bubbles touch each other, they
20 form a much larger foam cell, and the roughness produced is not well-controlled. For example, U.S. Pat. No. 2,393,298 to De Laney discloses rubber glove and like articles. The former is dipped first in an aqueous latex emulsion, followed by a coagulant dip to harden the first latex layer, and then
25 dipped in a foamed second latex layer, which is dipped in aerated runny latex, and the air bubbles burst to form a porous second layer. The former is then dipped in a coagulant layer to harden and stabilize the second foamed latex layer. In a second example, U.S. Pat. No. 4,589,940 to
30 Johnson discloses a method of making foamed, slip-resistant surfaces. The surface of the gloves provides a porous, foam surface, so that the gloves are breathable and have moistureabsorbing properties. The porous latex foam is applied to a woven or non-woven substrate. Since the substrate is porous
35 and the foamed latex is porous (40-95% porosity), the glove thus formed is breathable. The foam is stated to be abrasionresistant and to provide improved gripping action. In a third example, U.S. Pat. No. 4,497,072 to Watanabe discloses a porous, coated glove. The porous glove is made of a fabric
40 material with a coating layer that has sharp projections in the shape of broken bubbles, thereby providing tenacious gripping properties. The fabric glove base is formed from knitted fabrics, woven fabrics, or staple fiber materials. The fabric is then coated with a latex foaming solution, which is
45 solvent-based. The process of evaporation of the solvent is assisted by reduced pressure, which breaks the air bubbles, forming sharp edges. Multiple bubbles can collapse together, as shown in FIGS. 3 and 4, resulting in uncontrolled texture of the glove surface. In a fourth example, U.S.
50 Pat. No. 6,527,990 to Yamashita et al. discloses a method for producing a rubber glove. A rubber glove is produced by sequentially immersing a glove mold, first in a coagulating, synthetic rubber latex containing thermally expansible microcapsules and blowing agents. Next, it is immersed in
55 a rubber-incorporating latex to form a gelled rubber layer forming a rubber laminate. The rubber laminate is then heated to vulcanize the rubber laminate, and to expand the microcapsules and blowing agents creating a foam. The laminate is turned inside out with the expanded microcap
60 sule side forming the outer surface of the glove. This method produces a rubber glove, which is excellent in anti-blocking properties (no stickiness between two contacting gloves) and grip under dry or wet conditions, by a simple procedure and for a low cost.
65 Another approach for texturing latex gloves is to incorporate water-soluble particles in an uncured latex layer. For example, Japanese patent JP1258917 to Kishi discloses an