Plastic and nonmetallic article shaping or treating: processes – Mechanical shaping or molding to form or reform shaped article – To produce composite – plural part or multilayered article
Reexamination Certificate
1995-03-31
2001-08-28
Ortiz, Angela (Department: 1732)
Plastic and nonmetallic article shaping or treating: processes
Mechanical shaping or molding to form or reform shaped article
To produce composite, plural part or multilayered article
C264S306000, C264S307000
Reexamination Certificate
active
06280673
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to an improved method for making lubricous gloves for applying orthopaedic casting bandages of the type used to form orthopaedic casts and the gloves formed by the method. In particular, the invention relates to a coated glove having a lubricous coating to assist in applying orthopaedic bandages of the type having an uncured resin coating thereon.
BACKGROUND OF THE INVENTION
Plaster of paris casts have been used to immobilize body members for some time. These bandages are made by depositing plaster of paris on a reenforcing scrim material such as gauze. When the plaster of paris is dipped in water, reactions take place which result in the hardening of the cast material. Plaster of paris casts, however, suffer from a number of disadvantages. X-ray transmission through the cast to determine whether a fracture has properly set is extremely difficult. In addition, the cast is quite heavy and restricts the mobility of patients wearing the cast.
In order to overcome the disadvantages of plaster of paris casts, numerous attempts have been made to develop plastic or plastic-reenforced material as replacements for plaster of paris. U.S. Pat. Nos. 3,241,501 and 3,881,473 disclose casts which are made with a flexible fabric impregnated with a polymer which is capable of being cured by ultraviolet light.
Other attempts to replace plaster of paris casts are disclosed in German Offenlegenscrift Nos. 2353212 and 2357931, U.K. Patent No. 1,578,895 and PCT Application No. WO 81/00671. These bandages are open-weave fabrics coated with polyurethane prepolymers, that is, reaction products of isocyanates and polyols. The bandages are dipped into water in the same manner as the plaster of paris and then applied to the limb of the patient. The water causes the prepolymer to polymerize and form a rigid polymer structure.
More recently, it has been found that in working with such materials having prepolymer resin coating that the tackiness of the resin of the bandage can make working with the bandages difficult and cumbersome for the doctor. In an attempt to address this issue, a glove lubricant comprised of water, sorbitol, mineral oil and silicone fluid has been sold by 3-M Company, St. Paul, Minn., under the tradename Cast Cream™ with instructions to apply the lubricant to the gloves of one applying an isocyanatefunctional prepolymer coated cast after wrapping of the cast but before molding of the cast to avoid having the exposed casting material adhere to the gloves of the one applying the cast. This is disclosed in the background of U.S. Pat. Nos. 4,667,661 and 4,774,937.
The '661 and '937 patents are directed to addressing the adherence issue by providing the resin itself with a lubricant. The curable resin-coated sheet is prelubricated with a lubricant which is either a) bonded to the resin; b) added to resin or applied to the surface of the coated sheet; or c) provided in a combination of the bonding and surface application described. In many instances, however, the tacky feature of the orthopaedic bandage is desirable. As by way of example, when the applier is attempting to get the end of the bandage to stick to the surface of the bandage wrap in order to terminate the application of the bandage. The addition of lubricant in the resin permits relative slipping of the resin-coated sheet and requires molding the cast in position and holding it in position to prevent slippage.
Coatings for substrates having a lower coefficient of friction have been shown in U.S. Pat. No. 4,100,309 entitled, “Coated Substrate Having a Low Coefficient of Friction Hydrophilic Coating and a Method of Making the Same”. That reference describes a substrate which is coated with a polyvinylpyrrolidone-polyurethane interpolymer. Copending commonly assigned U.S. patent application Ser. No. 726,449, filed Jul. 8, 1991, entitled, “Method of Applying an Orthopaedic Bandage” discloses the use of a polyvinylpyrrolidone coated glove in the application of resinous substrate casting materials. Although the invention described in that application represents a significant advance in the science of orthopaedic bandages, there have been certain shortcomings discovered regarding those gloves. The glove described in the patent application in many instances perform too well. That is, the slipperiness of the gloves is present to such a great extent that ancillary manipulation is restricted. The ability of the applier of the casting material to handle pens and other utensils or to tear open foil packages to access the casting material is greatly restricted by the extreme slipperiness of the gloves. Furthermore, the durability of the gloves is at a point that is less than optimum.
Polyvinyl alcohol coated gloves have been found to have acceptable durability and slip levels but many coated gloves heretofore known require uneconomical high temperature methods of manufacture. Furthermore, the preferred, or most effectual thermally, reversible gelling agent used in existing polyvinyl alcohol glove manufacture is toxic and not applicable to medical glove applications.
SUMMARY OF THE INVENTION
The invention herein described allows a coating to be applied at room temperatures and with a conventional dipping apparatus using dip parameters that dry and cure onto a rubber latex substrate in sequences and times readily adaptable to conventional dip equipment. The coatings established in this manner have adequate adhesion to the rubber substrate. The gloves can be readily removed from the molds and-have the following in-use attributes:
a) the coated gloves do not adhere to tacky urethane prepolymer coated tapes;
b) the coating remains functional through the application of a desired number of tapes;
c) the coating when wetted with water has a preferred balance of slip-to-grip which allows smooth objects to be picked up, handled and, when desired, gripped, i.e., pens and instruments, and the coating permits the tearing open and manipulation of foil packages;
d) although the coating imbibes water when wet, it is less prone to self-adhesion than are existing polyvinylpyrrolidone constructions. This reduces the incidence of blocking in high humidity conditions and self-adhesion; and
e) the wet polyvinyl alcohol overdip of the present invention is compounded to be very thixotropic by incorporating a rhamsan gum. Relatively high levels of the predissolved rhamsan gum allows the manufacture of the gloves without any of the runback or dripoff problems usually associated with uncoagulated dips in glove manufacture.
In order to be an acceptable coating for the uses intended herein, the glove and coating must a) not be too brittle when dry, this would manifest itself in a cracking and flaking of the coating on the area of the gloves that are elongated the most, i.e., the cuff end of the coating which is stretched during donning to pull the glove over the thumb; b) the coating must not be too slippery when wet and must maintain a sufficient amount of the crosslinking when wet to prevent the coating from dissolving off the glove when in use with the casting tape; c) the coating must have sufficient thickness or staying power to process a desired number of tapes of the casting tape material; d) the coating is preferably applied at approximately ambient temperatures or, at a minimum, temperatures below 70° C.; and e) the coating should have a sufficiently low cost.
Polyvinyl alcohol solutions in water tend to be newtonian and flow excessively at most viscosities. Incorporation of a predetermined amount of rhamsan gum as a thickener effectively deposits a layer of the compound that does not drip off or flow back after the shear imposed during the dipping has occurred. Stopping the runback or excessive drain-off tendencies of the polyvinyl alcohol solutions results in gloves that are aesthetically acceptable and do not contribute to manufacturing problems of the running, non-thickened material. This ability to control the rheology allows the selection of an optimum ratio of contributing ingredients and all
Chen Mao-Ching
Green Richard
Stockum Glenn F.
DePuy Orthopaedics, Inc.
Ortiz Angela
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