1. Field of the Invention
Embodiments of the present invention generally relate to gloves and, more particularly, to polymeric gloves having raised features comprised of polymeric compositions disposed on the gloves and methods of making the gloves.
2. Description of the Related Art
Gloves are utilized in many fields for protecting workers, such as medical, industrial, and chemical industries as well as for household uses. In service, gloves include features to impart grip-ability and flexibility properties. Moreover, gloves are subjected to extensive wear from cuts, punctures, and abrasions.
Some polymeric gloves are formed from dipping a former into a polymeric composition, e.g., natural rubber latex, synthetic rubber latex, or the like, to form a coating in the shape of the former. However, such gloves are typically smooth and, therefore, do not offer adequate grip properties. Past attempts to impart grip properties to gloves have involved the use of caustic chemicals, salts, and require additional processes.
Also, for comfort and flexibility reasons, many gloves comprise foamed coatings. However, although such gloves may protect users against germs, viruses, and microbes as well as injuries, such gloves are not particularly abrasion- or cut-resistant, especially when foamed, leading to breaches during use and particularly during extended use. Moreover, gloves having open-celled foams have networks of inter-connecting cells and, generally, have a surface texture, which can aid in grip properties. However, open-celled foams do not adequately protect users from, for instance, medical hazards, such as germs, bacteria, viruses, and the like, as well as chemicals. Accordingly, users often double-glove, reducing comfort and grip.
Therefore, polymeric gloves offering excellent grip properties, represent advances in the art.
Polymeric gloves having polymeric raised features disposed thereon, and methods of making such gloves, according to embodiments of the present invention, substantially as shown in and/or described in connection with at least one of the figures, as set forth more completely in the claims, are disclosed. Various advantages, aspects, and novel features of the present disclosure, as well as details of an exemplary embodiment thereof, will be more fully understood from the following description and drawings.
So that the manner in which the above recited features of the present invention can be understood in detail, a more particular description of the invention, briefly summarized above, may be had by reference to embodiments, some of which are illustrated in the appended drawings. It is to be noted, however, that the appended drawings illustrate only typical embodiments of this invention and are therefore not to be considered limiting of its scope, for the invention may admit to other equally effective embodiments. It is to be understood that elements and features of one embodiment may be in other embodiments without further recitation and that, where possible, identical reference numerals have been used to indicate comparable elements that are common to the figures.
Embodiments according to the present invention comprise polymeric gloves, such as examination, surgical, and the like gloves, that have a plurality of polymeric raised features disposed on the polymeric gloves, creating gloves having enhanced grip-ability, wherein the plurality of polymeric raised features are comprised of a polymeric composition that is different than the polymeric composition of which the polymeric glove is comprised. In some embodiments of the present invention, the plurality of raised features is disposed on a polymeric layer(s) before curing the polymeric layer(s). Also, in some embodiments according to the invention, the polymeric composition, whether for the polymeric layer(s) or the raised features, is foamed, as discussed more fully below.
The process according to embodiments of the invention comprise the step of applying a coagulant onto a glove-shaped former and dipping the former into a first polymeric composition to form a polymeric layer, i.e., an unsupported glove, as discussed below. Subsequently, raised features, such as dots, mounds, bullets, straight or curved rails, circles, toroids, grains, and the like, optionally disposed in patterns, comprising a second polymeric composition, are disposed on the unsupported glove.
At step 112, a decision is made whether to cure the coating formed at step 110. If the answer is yes, the coating is cured, for example, by allowing the coating to drip dry or by applying heat to the coating, at step 114, for example, in an infrared oven. If the answer is no, no curing occurs and the method 100 proceeds to step 116, at which point, additional raised features, such as a plurality of polymeric features (as discussed below) are applied to the coating formed on the former, which may be the same or a different thermoplastic or thermoset composition as discussed above regarding the composition of which the coating is comprised. Table 2 depicts at least one exemplary formulation for a polyurethane composition. In some embodiments, the application of the additional raised features is a screen-printing step. The temperature of the polymeric composition during the screen-printing step is between 10-30° C. and, in at least one embodiment according to the invention, the temperature is approximately 23-25° C. At least one exemplary embodiment includes wherein the silkscreen is a stainless steel screen. In some embodiments according to the invention, the additional raised features are applied via an air-jetting deposition and/or 3D printing processes.
The method 100 next proceeds to step 118, at which point the coating and the features are cured, for example, in an oven. The method 100 then proceeds to step 120 at which point the method 100 ends. The curing step(s) comprise, in some embodiments, curing in an oven at, for example, 50° C. to 150° C. for approximately 10 to 60 minutes. In at least one exemplary embodiment of the invention, made from the foregoing method, gloves having the additional raised features disposed thereon are placed into an oven, for example, an infrared oven and heated to approximately 105° C. to 130° C. for approximately 5 to 30 minutes, forming a cured glove. In at least one embodiment according to the invention, curing is for approximately 7-8 minutes at 130° C. or, for example, 20 minutes at approximately 115° C. In some embodiments of the present invention, the heating or curing occurs twice, once before the additional raised features are disposed on the polymeric coating and once after the additional raised features are disposed thereon. Also, any of the additional raised features may comprise bullets, circles, toroids, dots, rings, waves, grains, or other additional raised features in varying sizes, shapes, or patterns, as discussed below.
Also, some steps of the preceding method 100 may be omitted or performed in a different sequence. Moreover, additional steps may be employed. For example, the coating on the former may be stripped, washed, and dried following step 110. Washing can be carried out at a temperature between approximately 25° C. and 60° C., for approximately 15 to 90 minutes. The gloves may then be dried in a tumble dryer for approximately 20 to 60 minutes at 50° C. to 70° C. These ranges allow different moisture contents, which may be important for the subsequent steps, for example, re-dressing the gloves on former and adding the additional raised features at step 110. Also, other finishing processes may be applied at this stage. For example, the coating and/or additional raised features may be cured by the application of heat.
Moreover, texturization or wrinkling processes may be added to the process, as are known to those in the art, to provide enhanced grip properties. Also, the method 100 may also comprise the application of a plurality of polymeric features comprising a third polymeric composition. In other words, for example, a base coating of a glove may comprise, a highly-carboxylated nitrile-butadiene composition, additional raised features comprising an acrylic composition, and yet other additional raised features comprising a polyurethane composition. A highly-carboxylated acrylonitrile-butadiene in this context indicates approximately 35-40% acrylonitrile, and is particularly oil-resistant. Also, embodiments according to the invention include wherein a glove is stripped from a former and re-dressed on a flat-shaped former before the additional raised features are applied thereto.
At least one exemplary embodiment according to the invention comprises a second polymeric layer. For example, the method for making a glove may further comprise a step for disposing a foamed polymeric layer on the former described above. The foamed polymeric layer may optionally have a coagulant disposed thereon and, subsequently, a second unfoamed polymeric composition disposed thereon and then a plurality of raised features may be disposed thereon, as described above. Alternatively, an unfoamed polymeric layer may be disposed on a former, a foamed layer may be disposed on the unfoamed polymeric layer (again, with or without a coagulant disposed on the foamed layer before the disposition of the unfoamed polymeric layer), the foamed layer and the unfoamed layer disposed thereon is inverted, so that the unfoamed layer is now an outer layer and the foamed layer is an inner layer, and additional raised features disposed thereon as described herein.
Thermosetting materials may include, for example, phenolics, silicones, polyesters, and sulfur-filled (or other vulcanizing agents), vulcanizable natural and synthetic rubber materials. Also, thickening agents, i.e., rheological modifiers, as known to those in the art to control the viscosity of the thermosetting and/or polymeric and/or thermoplastic materials, are contemplated herein.
At step 162, a decision is made whether to cure the unfoamed polymeric coating formed at step 160. If the answer is yes, the unfoamed polymeric coating is cured, for example, by allowing the coating to drip dry or by applying heat to the coating, at step 164, for example, in an infrared oven. If the answer is no, no curing occurs and the method 150 proceeds to step 166, at which point, the former having the unfoamed polymeric coating is dipped into a second foamed polymer composition to form a foamed polymeric layer on the foamed polymeric layer. Optionally, the first polymeric layer is dipped into a coagulant before being dipped into the second foamed polymer composition. At step 168, the unfoamed polymeric layer and the foamed polymeric layers are inverted, so that the foamed polymeric layer is an inner layer, i.e., a skin-contacting layer.
At step 170, additional raised features, such as a plurality of polymeric features (as discussed below) are applied to the coating formed on the former, which may be the same or a different thermoplastic or thermoset composition as discussed above regarding the composition of which the coating is comprised. Table 2 depicts at least one exemplary formulation for a polyurethane composition. In some embodiments, the application of the additional raised features is a screen-printing step. The temperature of the polymeric composition during the screen-printing step is between 10-30° C. and, in at least one embodiment according to the invention, the temperature is approximately 23-25° C. In some embodiments according to the invention, the additional raised features are applied via an air-jetting deposition and/or 3D printing processes.
The method 150 next proceeds to step 172, at which point the first polymeric layer and the second polymeric layers and the raised features are cured, for example, in an oven. The method 150 then proceeds to step 174 at which point the method 150 ends. The curing step(s) comprise, in some embodiments, curing in an oven at, for example, 50° C. to 150° C. for approximately 10 to 60 minutes. In at least one exemplary embodiment of the invention, made from the foregoing method, gloves having the additional raised features disposed thereon are placed into an oven, for example, an infrared oven and heated to approximately 105° C. to 130° C. for approximately 5 to 30 minutes, forming a cured glove. In at least one embodiment according to the invention, curing is for approximately 7-8 minutes at 130° C. or, for example, 20 minutes at approximately 115° C. In some embodiments of the present invention, the heating or curing occurs twice, once before the additional raised features are disposed on the polymeric coating and once after the additional raised features are disposed thereon. Also, any of the additional raised features may comprise bullets, circles, toroids, dots, rings, waves, grains, or other additional raised features in varying sizes, shapes, or patterns, as discussed below.
One exemplary formulation for a carboxylated nitrile-butadiene composition, according to embodiments, for a coating is shown in Table 1.
One exemplary formulation for a polyurethane composition, according to embodiments of the invention, of which the raised features are comprised and disposed on the coating, is shown in Table 2.
At least one acrylic composition, according to embodiments of the invention, for additional raised features disposed on the coating, is shown in Table 3. And, one exemplary composition comprises acrylic grade Polidisp 7730, manufactured by the Resiquimica Co. Embodiments according to the invention further comprise pressure sensitive acrylic formulations.
The polymeric coating 222 comprises one or more polymeric material or blends, as described above in Tables 1 and 2 or in other polymeric compositions. For example, the polymeric coating in accordance with the present invention may comprise natural or synthetic polymeric coatings or mixtures or blends thereof. For example, the polymeric composition may comprise a natural latex, such as guayule or natural polyisoprene, synthetic latexes, such as synthetic polyisoprene, carboxylated acrylonitrile butadiene, non-carboxylated acrylonitrile butadiene, acrylics, butyl latex, polychloroprene, nitriles, aqueous- and non-aqueous-polyurethanes, styrene-butadiene, acrylonitrile-butadiene, and the like, or mixtures or blends thereof. Similarly, the plurality of features 224 disposed on the polymeric coating 222 comprise polymeric compositions, which may be different than the composition comprising the polymeric coating 222. In one exemplary embodiment of the present invention, the polymeric coating 222 comprises an aqueous polyurethane material and, as discussed below, the additional raised features disposed thereon further comprise an aqueous polyurethane material or a nitrile-butadiene composition, or vice versa.
We have surprisingly found that additional raised features, disposed on an unsupported glove, comprising polyurethane have much greater grip properties than other polymeric materials. Also, the polyurethane features exhibit greater abrasion resistance. Furthermore, we have found that some polymeric compositions, when formed as either a coating or as features on the coating, are more suited for certain applications. For example, nitrile-butadiene rubbers offer good grip properties for dry in-service requirements while polyurethanes offer good grip properties for wet and oily environments. Therefore, a glove comprising a layer or coating of, for example, polyurethane and having additional raised features comprising nitrile, disposed on a surface of the unsupported glove, or vice-versa, can be used in both dry and wet/oily environments. Therefore, a user need not re-glove or have two different types of gloves because one glove, according to embodiments of the invention, will exhibit enhanced gripping properties for wet, dry, and oily environments.
The temperature of the polymeric composition may be controlled, as is known in the art, and may include additives, such as surfactants, to control or modify the physical properties of the composition and/or resulting article formed thereby. The composition may also comprise various accelerators, stabilizers, pigments, and the like. In some embodiments, the composition comprises additives, such as bentonite and other clays, minerals, silica, and like thickeners, to control the rheological properties of the composition. The composition of one or more embodiments may also include a cure package or vulcanization agents to promote cross-linking during the curing process, such as sulfur and/or other suitable crosslinking agents known to those in the art and activators, such as zinc oxide.
Embodiments according to the invention comprise polymeric compositions generally having a viscosity in the range of 250-5000 centipoise and further comprise commonly used stabilizers including but not limited to potassium hydroxide, ammonia, sulfonates, and the like. The composition may contain other commonly used ingredients such as surfactants, anti-microbial agents, fillers/additives, and the like. In at least one exemplary embodiment, the viscosity of the formulation for the additional raised features ranges from approximately 1000 cP to 40000 cP.
A typical coagulant comprises a 2-15 wt % calcium nitrate aqueous solution. The coagulant solution dries on the former. When the coagulant coated former is dipped into a polymeric composition, the composition is destabilized and gels. Other suitable coagulants include, but are not limited to, strong coagulants, such as calcium chloride or calcium citrate, and weak acids, such as tricarboxylic acid, acetic acid, formic acid, and other weak acid salts known to those in the art.
Other embodiments according to the present invention include where the polymeric composition is foamed, which is retained in the dipped article. The air content is typically in the 5 to 50% range on a volume basis. The composition may contain additional surfactants such as TWEEN 20 to stabilize the foamed composition. Once the composition is foamed with the desired air content and the viscosity is adjusted, refinement of the foam is undertaken by stirring the emulsion with an impeller driven at a fast speed and using a different impeller run at a reduced speed to refine the bubble size as is known to those of skill in the art.
An air content in the range of 5-15 volumetric percent results in foams that have closed cells, creating a foamed coating that is liquid impervious and has a spongy, soft feel. Some air cells, whether an open-celled or close-celled foam are disposed on the external surface of the coating, providing increased roughness and have the ability to remove boundary layer of oil and water from a gripping surface, providing increased grip properties. If the volumetric air content is in the range of 15-50% in a foamed coating, the air cells are adjacent to each other and expand during a vulcanization heating step and touch each other, merge, and burst. This process creates a foam having an open-celled structure comprising an intra-foam network of cells in fluid communication with each other. Therefore, open-celled foams absorb liquids into an internal matrix, enhancing the wet and oily grip properties of the glove. For example, if a drop of liquid is placed on a glove in the palm portion, the liquid penetrates the polymeric coating cells, as opposed to a closed-cell foam, which is impervious to liquids. Without intending to be bound by theory, it is similarly believed that a polymeric open-celled foam disposed as a coating on a liner allows the additional raised features disposed on the coating, as discussed below, to penetrate the internal cell matrix of the coating, forming a glove comprising more abrasion-resistant additional raised features that do not peel from the coating as readily. Moreover, the surface tension of the composition comprising the additional raised features can be varied to promote adherence to the foamed coating.
Also, at least one exemplary embodiment according to the invention comprises a foamed inner layer (not shown) disposed on an inner surface of the coating. The foamed inner layer may be an open-celled foam, comprising a network of inter-connected cells as is known to those in the art. Open-celled foam, when disposed on an inner layer of a glove, for example, a skin-contacting layer, absorb moisture and/or perspiration, promoting a hygienic condition and/or comfort.
Abrasion resistance and grip properties, such as dynamic and static coefficient of friction in different environments, such as wet, dry, and oily tests of various gloves according to embodiments of the invention exhibit surprisingly increased performance over prior art gloves. This phenomenon is true irrespective of whether the additional raised features are disposed on the coating as bullets, small rings, big rings, toroids, dots, waves, or grains. Without intending to be bound by theory, it is believed that one explanation for the increased grip performance is that when pulling forces reach a certain threshold, dragging is overcome and a sample is moved easier. This causes a drop in pulling and, consequently, the sample starts a new increase of resistance to movement. In other words, there is a build-up and drop of the drag.
Reference throughout this specification to “one embodiment,” “certain embodiments,” “one or more embodiments” or “an embodiment” means that a particular feature, structure, material, or characteristic described in connection with the embodiment is included in at least one embodiment of the invention. Thus, the appearances of the phrases such as “in one or more embodiments,” “in certain embodiments,” “in one embodiment” or “in an embodiment” in various places throughout this specification are not necessarily referring to the same embodiment of the invention. Furthermore, the particular features, structures, materials, or characteristics may be combined in any suitable manner in any one or more of the embodiments. Also, it is to be understood that polymeric, elastomeric, and latex are used interchangeably herein with respect to polymeric coatings and raised features made from polymeric compositions. Furthermore, it is to be understood that the terms coating and layer may be used interchangeably throughout the disclosure.
While the foregoing is directed to embodiments of the present invention, other and further embodiments of the invention may be devised without departing from the basic scope thereof, and the scope thereof is determined by the claims that follow.
This application claims the benefit of U.S. Provisional Application No. 61/908,553 under 35 USC 119(e), filed Nov. 25, 2013, and is incorporated by reference in its entirety.
Number | Date | Country | |
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61908553 | Nov 2013 | US |