Latex compound for manufacturing latex gloves and method of using the same

Abstract

To address the issue of reducing zinc oxide residue in latex glove products, one embodiment of the present invention provides a latex compound for use in the manufacturing process of latex gloves. The latex compound has the following characteristics: it contains 0.07 to 0.20% by mass of activated zinc oxide (ZnO). Furthermore, the activated zinc oxide has a BET specific surface area of ​​6.0 to 31.0 m. 2 / g.

Description

[Technical Field]

[0001] The present disclosure relates to methods of making latex gloves and the resulting latex glove products, and in particular to latex compounds used in such methods. [Background technology]

[0002] Conventionally, zinc oxide, particularly zinc(II) oxide (ZnO), is added as an activator to latex compounds for producing latex gloves. Vulcanization of latex activates the glove to have desirable mechanical properties for use, and the activator is crucial for the rate of vulcanization. An example of a prior art document describing such a conventional use is International Publication No. WO2019173863(A1).

[0003] Zinc oxide is also known to have antibacterial properties, a concept compatible with latex articles commonly used in the medical and healthcare fields. An example of such use is described in International Publication No. WO2021262487(A1). This prior art suggests the use of a zinc oxide composite material containing a core material (such as clay, talc, mica, or silica) coated with active zinc oxide. Adding this zinc oxide composite material to a latex compound formulation imparts antibacterial properties to the latex article.

[0004] In all instances, the use of zinc oxide in the art has resulted in zinc oxide residues distributed on the surface of latex glove products. The residue on the glove surface that comes into contact with the hand is a significant skin irritant and skin allergen. Many regulatory authorities have established standards that regulate the content of zinc oxide residues on latex glove products. Examples of such standards include BS EN 1186-9:2002 and BS EN 13130-1:2004, as well as the Japanese Ministry of Health and Welfare Notification No. 370 regarding compliance with Articles 7, Paragraph 1, and 10 of the Japanese Food Sanitation Act (Act No. 233) and its amendments, Part III, Section D, a) Rubber utensils (excluding nursing utensils).

[0005] None of the above prior art documents address the zinc residue problem or suggest a solution to suppress it. Therefore, there is a strong unmet need to reduce zinc oxide residue on latex gloves. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] International Publication No. 2019173863(A1) [Patent Document 2] International Publication No. 2021262487(A1) Summary of the Invention [Problem to be solved by the invention]

[0007] An object of the present invention is to provide a latex compound for manufacturing latex gloves that can address the above needs and thus effectively reduce the content of zinc oxide residue in the final latex glove product. [Means for solving the problem]

[0008] In a first aspect, one embodiment is a latex compound for use in a method for manufacturing a latex glove, the latex compound comprising 0.07 to 0.20 wt. % active zinc oxide (ZnO), the active zinc oxide being 6.0 to 31.0 m 2 The latex compound is characterized by having a BET specific surface area in the range of 1 / g.

[0009] The above objectives are achieved by using a latex compound having the above characteristics to manufacture latex gloves. The inventors believe that the activated form promotes the intended utility of zinc oxide in the latex compound (i.e., as an activator for vulcanization), thereby accelerating its decomposition and reducing residues. Through further experiments, the inventors also found the specific ranges of the amount of activated zinc oxide added (i.e., mass %) and BET specific surface area mentioned above. By controlling the key parameters within the ranges, zinc oxide residues were reduced to a sufficient level while ensuring proper vulcanization of the latex. Therefore, the mechanical properties of the product were not affected. Full details of the confirmatory experiments are provided below.

[0010] Preferably, active zinc oxide is the only activator in the latex compound. Formulation of a latex compound having a combination of inactive and active zinc oxide will not perform as effectively as a compound having active zinc oxide as the only activator.

[0011] In one embodiment, the latex compound further comprises a coagulant, an accelerator, and sulfur. Preferably, the coagulant is calcium carbonate (CaCO3) and calcium stearate (C 36 H 70 CaO4). Also preferably, the accelerator is one or more dialkyldithiocarbamates. In a more preferred embodiment, the accelerator is a combination of the following dialkyldithiocarbamates: sodium dibutyldithiocarbamate (NaBDC), zinc diethyldithiocarbamate (ZDEC), and zinc diethyldithiocarbamate (ZDBC). Also preferably, the sulfur is elemental sulfur in powder form. Suitable amounts of the additional components are described below.

[0012] Preferably, the activated zinc oxide is 6.0 to 6.5 m 2 / g, which showed better results in terms of reducing zinc residues while the mechanical properties of the latex glove remained unaffected.

[0013] Preferably, the activated zinc oxide also has an average pore diameter for adsorption within the range of 200 to 300 angstroms (Å).

[0014] Preferably, the activated zinc oxide also has a particle size within the range of 1.5 to 3.0 micrometers (μm).

[0015] In a second aspect, one embodiment is a method for manufacturing a latex glove, comprising drying a former coated with a latex compound, leaching the former, and peeling the latex glove from the former, wherein the latex compound contains 0.07 to 0.20% by mass of activated zinc oxide (ZnO), and the activated zinc oxide has a BET specific surface area within the range of 6.0 to 31.0 m 2 / g, characterized by the method.

[0016] The second aspect is closely related to the first aspect. The inventors have confirmed that the inventive concept underlying the first aspect can be applied to conventional methods for manufacturing latex gloves without requiring substantial changes to the method. Such compatibility with existing methods reduces implementation costs and thus further increases the advantages of the present invention.

[0017] The inventors have further found the following method variations that are compatible and included in the inventive concept of the present invention.

[0018] In one embodiment, the method is the method for manufacturing a latex glove described above, wherein the latex glove is a powder-free latex glove, and the method further includes a step of online chlorination treatment of the former.

[0019] In another embodiment, the method is the method for manufacturing a latex glove described above, wherein the latex glove is a powder-free latex glove, and the method further includes a step of offline chlorination treatment of the former.

[0020] In yet another embodiment, the method is a method for making a latex glove as described above, wherein the latex glove is a powdered latex glove.

[0021] The inventors have also found the following subranges of active zinc oxide loading and specific surface area to provide better results than the general ranges set forth above:

[0022] In one embodiment where the latex gloves are powder-free latex gloves and the method further comprises an on-line chlorination step of the type, the latex compound preferably comprises 0.12 to 0.20 wt. % of the active zinc oxide.

[0023] In one embodiment where the latex gloves are powder-free latex gloves and the method further comprises an offline chlorination step of the type, the latex compound preferably comprises 0.13 to 0.17 wt. % of the active zinc oxide.

[0024] In one embodiment where the latex glove is a powdered latex glove, the latex compound preferably contains 0.07 to 0.17% by weight of the active zinc oxide.

[0025] In any method variant, the activated zinc oxide is 6.0 to 6.5 m 2 It is preferable that the BET specific surface area is in the range of / g.

[0026] The latex gloves obtained from the second embodiment have a specific migration level of zinc of not more than 5 mg / kg when measured according to BS EN1186-9:2002 or BS EN13130-1:2004 standards, or an extractable zinc content of not more than 6 μg / mL when measured according to a) Rubber utensils (excluding baby utensils) in Japanese Ministry of Health and Welfare Notification No. 370 concerning compliance with the provisions of Article 7, Paragraph 1 and Article 10 of the Food Sanitation Act (Act No. 233) and its amendments, Part III, Section D. Full details of the confirmation tests and measurements are given below.

[0027] In a third aspect, one embodiment is a latex glove product obtained from a method according to any embodiment of the second aspect.

[0028] The principles of the present invention and its advantages will become apparent from the following description taken in conjunction with the accompanying drawings. [Brief explanation of the drawings]

[0029] [Figure 1] FIG. 1 shows a schematic flow chart of a method according to one embodiment for producing powder-free latex gloves with online chlorination. [Figure 2] FIG. 1 shows a schematic flow chart of a method according to one embodiment for producing powder-free latex gloves with offline chlorination treatment. [Figure 3] FIG. 1 shows a schematic flow chart of a method according to one embodiment for producing powdered latex gloves. DETAILED DESCRIPTION OF THE INVENTION

[0030] It should be understood that the following detailed description is directed to embodiments shown as examples only to illustrate the concepts of the present invention. The present invention is not limited in nature to the particular embodiments described, which may, of course, vary. It should also be understood that the terminology used herein is for the purpose of describing particular embodiments only, and is not intended to be limiting, since the scope of the present invention will be limited only by the appended claims.

[0031] The detailed description is divided into various sections solely for the convenience of the reader, and disclosure appearing in any section may be combined with disclosure appearing in another section.

[0032] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs.

[0033] It should be noted that as used herein and in the appended claims, the singular forms "a," "an," and "the" include plural references unless the context clearly dictates otherwise.

[0034] The term "about," when used before a numerical designation, such as a dimension, time, amount, etc., including a range, indicates approximation that may be adjusted by (+) or (-) 10%, 5%, or 1%, or any subrange or subvalue therebetween.

[0035] "Comprising" or "comprises" is intended to mean that the compositions and methods include the recited elements but do not exclude others. "Consisting essentially of," when used to define compositions and methods, is intended to mean excluding other elements from any essential significance to the combination for the described purpose. Thus, a device or method consisting essentially of elements defined herein does not exclude other materials or steps that do not materially affect the basic and novel characteristics of the claimed invention. "Consisting of" is intended to mean excluding other components and other essential method step elements, however minor. Embodiments defined by each of these transition terms are within the scope of the present invention.

[0036] "Latex gloves" refers to gloves made from natural latex, as distinguished from gloves made from synthetic latex, such as nitrile or neoprene gloves.

[0037] "Coagulating agent" or "coagulant" refers to a substance added to cause latex particles to clump together on the former to form a weak, water-containing film (i.e., a wet gel). Exemplary coagulating agents include calcium nitrate, calcium chloride, and ammonium nitrate.

[0038] "Accelerator" refers to a chemical added to a rubber / latex compound to increase the rate of vulcanization. Exemplary accelerators include dithiocarbamates such as zinc dibutyldithiocarbamate (ZDBC), zinc diethyldithiocarbamate (ZDEC), and sodium dibutyldithiocarbamate (NaBDC).

[0039] "Activators" refer to inorganic and organic chemicals used to activate the action of accelerators. These chemicals reduce vulcanization time (cure time) by increasing the rate of vulcanization. Exemplary activators include zinc(II) oxide (ZnO).

[0040] "Antioxidant" refers to a substance added to a glove product to protect it from attack / degradation by oxygen (O2), thereby extending its useful life. Exemplary antioxidants include compounds with phenol or amine functional groups.

[0041] "Preservative" refers to a chemical added to a rubber / latex compound to inhibit agglomeration of the rubber / latex particles, thereby stabilizing the compound during the aging period. Exemplary preservatives include ammonia (NH3) and potassium hydroxide (KOH).

[0042] "Water" includes tap water, distilled water, or otherwise purified water, with or without impurities or additives such as detergents or water softeners / hardeners, so long as it consists essentially of water and is deemed suitable for corresponding use in an industrial facility for producing medical-grade products, such suitability being determinable by one skilled in the relevant art.

[0043] The remainder of this detailed description describes the use of a latex compound (embodiment according to the first aspect) in a method (embodiment according to the second aspect) for producing a latex glove (embodiment according to the second aspect). The description is organized around exemplary variations of the method and latex glove: first, a method for producing powder-free latex gloves, where the chlorination of the mold is performed by online chlorination; second, a method for producing powder-free latex gloves, where the chlorination of the mold is performed by offline chlorination; and third, a method for producing powdered latex gloves. It will be clear that the concept of the present invention applies to all variations of the method.

[0044] Powder-free latex glove production with on-line chlorination. FIG. 1 shows a schematic flow chart of one embodiment of a method for manufacturing powder-free latex gloves with online chlorination. In this embodiment, the method 100 for manufacturing latex gloves includes the subcomponent steps of mold preparation 110, coagulant dip 120, latex compound dip 130, beading 140, leaching 150, online chlorination 160, cuffing 170, and stripping 180. All of the aforementioned work steps are performed continuously. In this embodiment, technical features according to the inventive concept are embodied in connection with the latex compound dip 130 step, as will become apparent in the latter part of this detailed description. The overview of the method 100 shown in FIG. 1 also illustrates that the inventive concept may be incorporated into existing methods in the art with minimal complexity.

[0045] In this embodiment, the method 100 begins with mold preparation 110. By mold, we mean a mold embodying the shape of the intended glove product. The mold is a conventional male mold that may be made of a suitable metal or ceramic. Here, the mold may be clean or may have been returned from the stripping step 180. In a preferred step of mold preparation 110, the mold is washed with an aqueous acid solution containing 0.2-2.0% by weight of an acidic compound per volume of water at a temperature of 50-60°C for 12-15 seconds. The acidic compound is preferably a strong acid such as hydrochloric acid (HCl) or nitric acid (HNO). The mold is then washed with an alkaline aqueous solution, preferably twice: once with a first alkaline aqueous solution containing 0.1 to 2.0% by weight of a known alkaline detergent per volume of water at a temperature of 60 to 70° C. for 8 to 12 seconds, and once with a second alkaline aqueous solution containing 0.8 to 1.3% by weight of a known alkaline detergent per volume of water (which may or may not be the same detergent as in the first alkaline wash) for an additional 8 to 12 seconds at a temperature of 60 to 70° C. Thereafter, the mold is washed with water, preferably twice, for 8 to 12 seconds each time at a temperature of 70 to 100° C.

[0046] The next coagulant dip 120 step involves immersing the form resulting from the preparation step 110 in a coagulant containing 2.0-5.0% by weight of calcium stearate (C ) as the primary coagulant per volume of water. 36 H 70 The second coagulant is preferably an aqueous solution containing calcium nitrate (CaO4) and, preferably, 10.0-15.0% by weight per volume of water of a second coagulant known in the art. Most preferably, the second coagulant is calcium nitrate (Ca(NO3)2). The immersion / dipping is preferably carried out for 12-15 seconds at a coagulant temperature of 50-70°C. Consequently, the mold is coated with the coagulant and then dried for 120-140 seconds at a temperature of 70-120°C. The drying is preferably carried out in an enclosed space, preferably in an oven to prevent contamination by airborne contaminants, and more preferably in a series of ovens at decreasing temperatures within the general ranges mentioned above. The method 100 then proceeds to the latex compound dip 130 step.

[0047] In this embodiment, the latex compound dip 130 step involves immersing a former already coated with dry coagulant into a latex compound. The coagulant induces deposition of latex particles onto the former to form a wet film that will constitute the main body of the intended latex glove.

[0048] The latex compound in this preferred embodiment is formulated according to the unique technical concept of the present invention. Specifically, the preferred latex compound essentially consists of: (i) 75 to 80% by weight of latex; (ii) 0.5 to 0.7% by weight of metallic titanium; (iii) 0.07 to 0.20% by weight, more preferably 0.12 to 0.20% by weight of active zinc oxide (ZnO), the preferred characteristics of which are further described below; (iv) 0.2 to 0.4% by weight of zinc diethyldithiocarbamate (ZDEC); (v) (vi) 0.01 to 0.05% by mass of sodium dibutyldithiocarbamate (NaBDC), (vii) 0.4 to 0.6% by mass of sulfur (S8), (viii) 0.4 to 0.6% by mass of an antioxidant, (ix) 0.01 to 0.15% by mass of one or more preservatives, and (x) the balance being calcium carbonate (CaCO3). In this embodiment, the latex compound having this formulation can be prepared by any known mixing means conventionally used to prepare liquid dispersion materials.

[0049] The active zinc oxide (ZnO) is preferably 6.0 to 31.0 m 2 / g, more preferably 6.0 to 6.5m 2 / g, and even more preferably, the activated zinc oxide also has an adsorption average pore size in the range of 200 to 330 angstroms and / or a particle size in the range of 1.5 to 3.0 micrometers.

[0050] In the latex compound dipping step 130, the mold is immersed in the latex compound for 15 to 25 seconds at a temperature of 25 to 35°C. Then, the mold coated with the wet latex compound due to the effect of the coagulant is dried for 90 to 110 seconds at a temperature of 70 to 120°C. For the same reasons as above, the drying is preferably carried out in an oven. The mold coated with the dry latex compound film is then sent to the next beading step 140.

[0051] In this embodiment, the beading 140 step involves rolling up the open-ended sleeve of the latex glove while it is still coated on the former. In this preferred embodiment, the rolling is accomplished by feeding the former through a series of brushes, each of which gradually rolls up the open end of the latex glove, thereby rounding the edge of the end. Further details of beading applicable to this embodiment can be found in the art. The beading 140 step is completed by drying the beaded latex glove at a temperature of 80-100°C for 80-90 seconds, preferably in an oven, for the same reasons as above.

[0052] In this embodiment, a subsequent leaching step 150 is performed to remove residual chemicals from the latex gloves still deposited on the former. The leaching is performed by dipping the former in water at a temperature of 40-90°C for 60-90 seconds. Preferably, leaching 150 is performed in a series of tanks at increasing temperatures within the general ranges described above. The leached latex gloves are then dried at a temperature of 75-90°C for 850-900 seconds, preferably in an oven, more preferably in a series of ovens, for the same reasons described above. After drying, the latex gloves are then cooled at ambient temperature for 40-60 seconds, preferably in a liquid cooling medium, preferably water. Preferably, cooling is performed in a series of tanks.

[0053] An online chlorination step 160 is then performed immediately and consecutively after the leaching step 150 described above. While the concepts of the present invention apply to any known liquid or gaseous chlorinating agent, in this exemplary embodiment, the chlorinating agent is chlorine gas (Cl2). In a preferred embodiment, the online chlorination step 160 is performed in a closed chamber, where the latex gloves are exposed to 600-1,200 ppm chlorine gas at ambient temperature for 30-40 seconds. Preferably, the latex gloves exiting the chlorination chamber enter a neutralization tank or series of neutralization tanks to remove any chlorine gas residue or its derivatives on the gloves. In a preferred embodiment, the series of neutralization tanks includes an immersion tank and a neutralizer tank, followed by three rinse tanks. In the immersion tank, the latex gloves are immersed in a liquid medium, preferably water, at ambient temperature for 5-15 seconds. In the neutralizer tank, the latex gloves are immersed in a neutralizer, preferably an aqueous solution of a strong base, which in the exemplary embodiment is 0.1% by weight potassium hydroxide (KOH) in water, for 5-15 seconds at ambient temperature. In the exemplary embodiment, three rinse tanks contain water at different temperatures, with the first tank at ambient temperature and the second and third tanks at 65-80°C. The latex gloves are immersed in the rinse tanks for a total of 30-45 seconds. The latex gloves are then dried in an oven or series of ovens at 55-65°C for 150-200 seconds and then sent to the cuffing 170 step.

[0054] The cuffing 170 step is preferably accomplished by similar means to the beading 140 step, described more fully above. Here, too, the former is fed into a series of brushes, each of which gradually rolls up the open end of the latex glove. The primary difference between the beading 140 and cuffing 170 steps is the degree of rolling, with the beading 140 step rolling up the latex glove just enough to round the edges of the open end of the glove, and the cuffing 170 step rolling up the glove further to the center of the open end to facilitate the subsequent stripping 180 step. The associated brush and machine configurations are adjusted to achieve this objective according to conventional knowledge.

[0055] A stripping step 180 follows, whereby the now fully formed, treated, and stabilized latex glove is removed from the former. In the preferred embodiment, the stripping step is accomplished by grasping the latex glove and pulling it from the former, although in the preferred embodiment, stripping step 180 may be accomplished by any conventional means. At the end of stripping step 180, the latex glove is sent to storage and the empty former is returned to the mold preparation 110 step, where it is cleaned and prepared for the next cycle of the coagulant dip 120 through stripping 180 steps.

[0056] Powder-free latex glove production with off-line chlorination. FIG. 2 shows a schematic flow chart of a method for manufacturing powder-free latex gloves with offline chlorination according to one embodiment. In this embodiment, method 200 for manufacturing latex gloves includes the subcomponent steps of mold preparation 210, coagulant dip 220, latex compound dip 230, beading 240, leaching 250, cuffing 260, stripping 270, and offline chlorination 280. The aforementioned steps are performed continuously except for offline chlorination 280, which is a batch operation. It can be appreciated that the primary difference between the exemplary embodiments of the online-chlorination variant (100, FIG. 1) and the offline-chlorination variant (200, FIG. 2) is the order of the respective chlorination steps (160, 280), although such a difference is not required, nor is it the only difference between the two variants, as will be described further. In this embodiment, the technical features according to the inventive concept are also embodied in connection with the step of latex compound dipping 230, which will become clear in the latter part of this detailed description. The overview of the method 200 shown in Figure 2 also shows that the inventive concept may be incorporated into existing methods in the art with as little complexity as possible.

[0057] In this embodiment, method 200 begins with mold preparation 210, further description of which follows the description above for mold preparation 110 step shown in FIG. 1. Here, the mold may be clean or may have been returned from stripping 270. In a preferred mold preparation 210 step, the mold is washed with an acidic aqueous solution containing 0.2-2.0% by weight of an acidic compound per volume of water at a temperature of 50-60°C for 5-10 seconds. The acidic compound is preferably a strong acid, such as hydrochloric acid (HCl) or nitric acid (HNO). The mold is then washed with an alkaline aqueous solution containing 0.1-2.0% by weight of a known alkaline cleaner per volume of water at a temperature of 60-70°C for 2-8 seconds. Preferably, the mold is further cleaned by brushing. Thereafter, the mold is washed with water, preferably twice, for 2-8 seconds each time at a temperature of 80-100°C, and then preferably dried in an enclosed space, such as an oven, to prevent contamination by airborne contaminants. The drying temperature is preferably within a range of 60 to 70° C., and the drying time is preferably within a range of 15 to 20 seconds.

[0058] The next step, coagulant dip 220, involves immersing the former from preparation step 210 in a coagulant, which is an aqueous solution containing 3.0-10.0% by weight of calcium carbonate (CaCO3) as the primary coagulant per volume of water, and preferably 4.0-12.0% by weight of a secondary coagulant known in the art per volume of water. Most preferably, the secondary coagulant is calcium chloride (CaCl2). The immersion / dip is preferably performed at a coagulant temperature of 70-90°C for 5-10 seconds. The resulting coagulant-coated former is then dried at a temperature of 70-130°C for a total time of 30-40 seconds, preferably in an oven, more preferably in a series of ovens at decreasing temperatures within the general ranges mentioned above. The method 200 then proceeds to the latex compound dip 230 step.

[0059] Here, the role of the coagulant that has now been coated and dried on the mold in the latex compound dip 230 step follows the above description regarding the latex compound dip 130 step shown in FIG.

[0060] The latex compound in this preferred embodiment is formulated according to the unique technical concept of the present invention. Specifically, the preferred latex compound essentially consists of: (i) 75 to 80% by weight of latex; (ii) 0.2 to 0.6% by weight of metallic titanium; (iii) 0.07 to 0.20% by weight, more preferably 0.13 to 0.17% by weight of active zinc oxide (ZnO), the preferred characteristics of which are further described below; (iv) 0.2 to 0.4% by weight of zinc diethyldithiocarbamate (ZDEC); (v) (vi) 0.01 to 0.05% by mass of sodium dibutyldithiocarbamate (NaBDC), (vii) 0.6 to 0.8% by mass of sulfur (S8), (viii) 0.4 to 0.6% by mass of an antioxidant, (ix) 0.01 to 0.90% by mass of one or more preservatives, and (x) the balance being calcium carbonate (CaCO3). In this embodiment, the latex compound having this formulation can be prepared by known mixing means conventionally used to prepare liquid dispersion materials.

[0061] The active zinc oxide (ZnO) is preferably 6.0 to 31.0 m 2 / g, more preferably 6.0 to 6.5m 2 / g, and even more preferably, the activated zinc oxide also has an adsorption average pore size in the range of 200 to 330 angstroms and / or a particle size in the range of 1.5 to 3.0 micrometers.

[0062] In the latex compound dipping step 230, the mold is immersed in the latex compound for 10 to 20 seconds at a temperature of 25 to 35°C. Then, the mold coated with the wet latex compound due to the effect of the coagulant is dried for 40 to 60 seconds at a temperature of 70 to 110°C. For the same reasons as above, the drying is preferably carried out in an oven. The mold coated with the dry latex compound film is then sent to the next beading step 240.

[0063] In this embodiment, the general description of the beading 240 step follows the description above of the beading 140 step shown in Figure 1. Here, the beading 240 step is completed by drying the beaded latex glove at a temperature of 110-125°C for a total time of 10-15 seconds, preferably in an oven, or more preferably in a series of ovens, for the same reasons as above.

[0064] In this embodiment, a subsequent leaching step 250 is performed to remove residual chemicals from the latex gloves still deposited on the former. The leaching is performed by dipping the former in water at a temperature of 80-100°C for 30-45 seconds. Preferably, leaching 250 is performed in a series of tanks at a temperature within the general ranges described above. The leached latex gloves are then dried at a temperature of 250-130°C for a total time of 220-240 seconds, preferably in an oven for the same reasons as above, and more preferably in a series of ovens at increasing temperatures within the general ranges described above.

[0065] In this embodiment, the general description of the cuffing 260 and stripping 270 steps follows the description above of the cuffing 170 and stripping 180 steps shown in Figure 1, with a notable difference: In the variation shown in Figure 2, after the stripping 270 step, the latex gloves are not yet sent to storage; instead, the latex gloves are sent to an offline chlorination 280 step.

[0066] An offline chlorination step 280 is then performed discontinuously after the stripping step 270. While the concept of the present invention applies to any known liquid or gaseous chlorination agent, in this exemplary embodiment, the chlorination agent is a mixture of sodium hypochlorite (NaOCl) and silicone in water. At this point, the fully formed latex gloves, stripped from the former, are first washed in water at ambient temperature for 10 minutes. The gloves are then chlorinated by washing in the chlorination agent, preferably a mixture of 10-20% by weight sodium hypochlorite and 45-55% by weight silicone (TSC 29.0-35.0%) per volume of water, for another 20-30 minutes. Thereafter, the gloves, which may still contain chlorination residues, are further neutralized by washing in water at ambient temperature for 40-60 minutes. To promote complete neutralization, the gloves are preferably washed at least four times during this entire period. More preferably, all of the aforementioned washing steps are carried out in the same vessel at ambient temperature, with the respective water / agents being drained from the vessel at the end of each washing step and filled into the vessel at the start of each washing step. Finally, the latex gloves are dried in an oven at 100-130°C for 70 minutes, then allowed to cool to ambient temperature, and then sent to storage.

[0067] Powdered latex glove manufacturing FIG. 3 shows a schematic flow chart of a method for manufacturing powdered latex gloves according to one embodiment. In this embodiment, method 300 for manufacturing latex gloves includes the subcomponent steps of mold preparation 310, coagulant dip 320, latex compound dip 330, beading 340, leaching 350, powdering 360, cuffing 370, and stripping 380. The aforementioned steps are performed sequentially. It can be appreciated that the primary difference between the exemplary embodiments of the powderless variants (100 and 200, FIGS. 1 and 2) and the powdered variant (300, FIG. 3) is the presence or absence of a chlorination step (160, FIG. 1; 280, FIG. 2) and a powdering step (360, FIG. 3), although such differences are not the only differences between the variants, as will be described further. In this embodiment, the technical features according to the inventive concept are also embodied in connection with the latex compound dip 330 step, which will become clear in the latter part of this detailed description. The overview of the method 300 shown in Figure 3 also shows that the inventive concept may be incorporated into existing methods in the art with as little complexity as possible.

[0068] In this embodiment, method 300 begins with mold preparation 310, further description of which follows the description above for mold preparation 110 shown in FIG. 1 . Here, the mold may be clean or may have been returned from stripping 380. In a preferred mold preparation 310 step, the mold is washed with an acidic aqueous solution containing 0.2-2.0 wt. % acidic compound per volume of water at a temperature of 25-40°C for 5-10 seconds. The acidic compound is preferably a strong acid, such as hydrochloric acid (HCl) or nitric acid (HNO). The mold is then washed with an alkaline aqueous solution containing 0.1-2.0 wt. % known alkaline cleaner per volume of water at a temperature of 25-40°C for 5-10 seconds. The mold is then washed with water, preferably twice, for 2-8 seconds each time at a temperature of 80-100°C, and then preferably dried in an enclosed space, such as an oven, to prevent contamination by airborne contaminants. The drying temperature is preferably within a range of 90 to 120° C., and the drying time is preferably within a range of 15 to 20 seconds.

[0069] The next step, coagulant dip 320, involves immersing the former resulting from preparation step 310 in a coagulant. Here, the coagulant is an aqueous solution containing 3.0-10.0% by weight of calcium carbonate (CaCO3) as the primary coagulant per volume of water, and preferably 4.0-10.0% by weight of a secondary coagulant known in the art per volume of water. Most preferably, the secondary coagulant is calcium nitrate (Ca(NO3)2). The immersion / dipping is preferably performed at a coagulant temperature of 70-90°C for 5-10 seconds. The resulting coagulant-coated former is then dried, preferably in an oven, for 30-40 seconds at a temperature of 100-130°C. The method 300 then proceeds to the latex compound dip 330 step.

[0070] Here, the role of the coagulant that has now been coated and dried on the mold in the latex compound dip 330 step follows the above description regarding the latex compound dip 130 step shown in FIG.

[0071] The latex compound of this preferred embodiment is formulated according to the unique technical concept of the present invention. Specifically, the preferred latex compound essentially consists of (i) 70 to 75 wt. % latex, (ii) 0.07 to 0.20 wt. %, more preferably 0.07 to 0.17 wt. % active zinc oxide (ZnO), the preferred characteristics of which are further described below, (iii) 0.1 to 0.3 wt. % zinc diethyldithiocarbamate (ZDEC), (iv) 0.10 to 0.20 wt. % zinc dibutyldithiocarbamate (ZDBC), (v) 0.3 to 0.6 wt. % sulfur (S8), (vi) 0.2 to 0.5 wt. % antioxidant, (vii) 0.01 to 0.50 wt. % one or more preservatives, (viii) 0.15 to 0.25 wt. % known antifoaming agent, and (x) the balance calcium carbonate (CaCO3). In this embodiment, the latex compound of the formulation can be prepared by known mixing means conventionally used to prepare liquid dispersion materials.

[0072] The active zinc oxide (ZnO) is preferably 6.0 to 31.0 m 2 / g, more preferably 6.0 to 6.5m 2 / g, and even more preferably, the activated zinc oxide also has an adsorption average pore size in the range of 200 to 330 angstroms and / or a particle size in the range of 1.5 to 3.0 micrometers.

[0073] In the latex compound dipping step 330, the mold is immersed in the latex compound for 15 to 25 seconds at a temperature of 25 to 35°C. Then, the mold coated with the wet latex compound due to the effect of the coagulant is dried for 80 to 100 seconds at a temperature of 120 to 150°C. For the same reasons as above, the drying is preferably carried out in an oven. The mold coated with the dry latex compound film is then sent to the next beading step 340.

[0074] In this embodiment, the general description of the beading 340 step follows the above description of the beading 140 step shown in Figure 1. Here, the beading 340 step is completed by drying the beaded latex glove at a temperature of 120 to 140°C for 25 to 35 seconds, preferably in an oven for the same reasons as above.

[0075] In this embodiment, a subsequent leaching step 350 is performed to remove residual chemicals from the latex gloves still deposited on the formers. The leaching is performed by dipping the formers in water at a temperature of 70-100°C for a total time of 60-80 seconds. Preferably, leaching 350 is performed in a series of tanks at a temperature within the general ranges mentioned above. More preferably, the series of four leaches is divided into two consecutive pre-leaches followed by two consecutive post-leaches, with drying steps between the pre-leaches and post-leaches at 100-140°C for a total time of 340-400 seconds, preferably in a series of four ovens. In this embodiment, the formers with the deposited latex gloves are not dried after leaching (or, in the preferred embodiment, after the final post-leaching) but are instead sent to the powdering step 360.

[0076] The powdering 360 step follows the infusion 350 step. While the concepts of the present invention apply to any known powdering medium, in this exemplary embodiment, the powdering medium is a water dispersion of cornstarch powder, preferably prepared from 2.0 to 8.0% by weight cornstarch powder per volume of water. In a preferred embodiment, the powdering medium is provided at ambient temperature. The gloved former is immersed in the powdering medium for 3 to 8 seconds and then further processed for the cuffing 370 step.

[0077] In this embodiment, the general description of the cuffing 370 and stripping 380 steps follows the description above of the cuffing 170 and stripping 180 steps shown in FIG. 1, after which the latex gloves are dried at 80-120° C. for 900-1,200 seconds, preferably in an oven, before being sent to storage. [Example]

[0078] Example of an embodiment Methods according to the above embodiments were carried out in accordance with the following description and further details set out in Table 1 below.

[0079] First set of working examples The first set of examples corresponds to Examples 1-6 in Table 1. They were carried out according to the exemplary embodiment of the manufacture of powder-free latex gloves with online chlorination process described above in connection with FIG.

[0080] In the mold preparation step 110 for this set of examples, a mold made of a known ceramic was first washed in an acid tank containing 3,200 liters of an aqueous solution of 1.0% by weight nitric acid (HNO3) per volume of water at 55°C for 13.6 seconds. The mold was then washed in two alkaline tanks for 10 seconds in each tank. Each alkaline tank contained 4,600 liters of an aqueous solution of a known alkaline cleaner at 65°C. Both alkaline tanks contained the same alkaline cleaner but at different concentrations: 0.8% by weight detergent per volume of water in the first alkaline tank and 1.0% by weight detergent per volume of water in the second alkaline tank. The mold was then washed with water for 10 seconds in each tank in a series of two tanks. Each tank contained 4,700 liters of water at a different temperature: 80°C in the first tank and 85°C in the second tank.

[0081] The coagulant dip 120 step in this set of examples involves immersing the mold in a solution of 12.0% by weight calcium nitrate (Ca(NO3)2) and 3.2% by weight calcium stearate (C(NO3)2) per volume of water. 36 H 70 The molds were dipped into a tank containing 8,500 liters of an aqueous solution containing CaO4 at 56°C for 13.5 seconds. The molds were then dried in a series of two industrial ovens for 65 seconds in each oven, the first at 115°C and the second at 80°C, until the water was substantially removed. In those examples involving a continuous process, the industrial ovens (along with similar ovens described below) were conveyor ovens.

[0082] The latex compound dip 130 step in this set of examples involved immersing the mold in a tank containing 9,500 liters of latex compound at 30°C for 21 seconds.

[0083] The latex compound contained 77.64 wt. % latex, 0.62 wt. % titanium metal, active zinc oxide, the characteristics and amounts of which are further set forth in Table 1 below, 0.31 wt. % zinc diethyldithiocarbamate (ZDEC), 0.23 wt. % zinc dibutyldithiocarbamate (ZDBC), 0.01 wt. % sodium dibutyldithiocarbamate (NaBDC), 0.54 wt. % sulfur (S8), 0.54 wt. % antioxidant, 0.11 wt. % preservatives of potassium hydroxide (KOH) and 0.03 wt. % ammonia (NH3), and the balance calcium carbonate (CaCO3).

[0084] The latex compound coated former was then dried in an industrial oven at 105°C for 103.5 seconds and then sent to the beading 140 step.

[0085] Beading 140 in this set of examples was performed according to one embodiment described above with respect to FIG. 1, followed by drying the mold with the latex glove still on it in an industrial oven at 85° C. for 87 seconds.

[0086] Next, the leaching step 150 in this set of examples was carried out in six leaching tanks, each containing 6,700 liters of water. The latex glove-attached formers were held in each leaching tank for 14.5 seconds. The temperatures in the leaching tanks, numbered 1 through 6, were set as follows: 45, 70, 75, 75, 80, and 80°C, and the latex glove-attached formers were placed in these tanks. The leached latex gloves, still on the formers, were then dried in a series of six ovens at a constant temperature of 85°C for 872 seconds across all six ovens. The latex gloves were then cooled at ambient temperature in four tanks, each containing 6,400 liters of water, for 13.5 seconds in each tank.

[0087] The formers, with the latex gloves still deposited, then proceeded to an on-line chlorination step 160. This step was carried out in a 16,500 liter on-line (i.e., continuous) chlorination chamber, where the latex gloves were exposed to 900 ppm chlorine gas (Cl2) at ambient temperature for 36.5 seconds. The latex gloved formers were then placed in a series of neutralization tanks: a 4,000 liter immersion tank, a 4,800 liter neutralizer tank, and one 4,800 liter ambient temperature rinse tank, followed by two 6,700 liter hot rinse tanks. The latex gloves were immersed in the water contained in the immersion tank for 8 seconds at ambient temperature, then immersed in 0.1 wt. % potassium hydroxide (KOH) in water contained in the neutralizer tank for 10 seconds at ambient temperature, then immersed in water contained in the ambient temperature rinse tank for 10 seconds at ambient temperature, and then immersed in water contained in the two hot rinse tanks for 14.5 seconds in each hot rinse tank at 70° C. The rinsed latex gloves on the formers were then dried in an industrial oven at 660° C. for 169 seconds.

[0088] The cuffing 170 step in this set of examples was performed according to one embodiment described above with respect to FIG.

[0089] Finally, the latex gloves were stripped from the formers according to a preferred embodiment in stripping step 180. The formers were then returned to the beginning of method 100 in the step of mold preparation 110. The so-stripped latex gloves were collected for further testing and analysis of their zinc residue content and mechanical properties. For details of these tests and analyses, see further below, Analysis of Latex Gloves from the Preferred Embodiments, and Table 2.

[0090] Second set of working examples The second set of examples corresponds to Examples 7-8 in Table 1. They were carried out according to the exemplary embodiment of the manufacture of powder-free latex gloves with offline chlorination treatment described above in connection with FIG.

[0091] In the mold preparation 210 step of this set of examples, a mold made of a known ceramic was first washed for 5.5 seconds at 55°C in an acid tank containing 1,500 liters of an aqueous solution of 1.0 wt% nitric acid (HNO3) per volume of water. Next, the mold was washed for 10 seconds in an alkaline tank containing 850 liters of an aqueous solution of a known alkaline cleaner at 65°C, at 0.5 wt% per volume of water. The mold was then brushed and then washed in a series of two tanks, each containing 1,700 liters of water at 94°C, for 6.6 seconds in the first tank and 4.4 seconds in the second tank. The mold was then dried in an oven at 65°C for 15.5 seconds.

[0092] In the coagulant dip 220 step in this set of examples, the formers were dipped into a tank containing 1,700 liters of an aqueous solution containing 7.0% by weight calcium chloride (CaCl) and 4.0% by weight calcium carbonate (CaCO) per volume of water at 75°C for 5.5 seconds. The formers were then dried in a series of two industrial ovens, one at 115°C and the other at 85°C, for 19.8 seconds in each oven, until the water was substantially removed. In those examples involving semi-continuous processes, the industrial ovens (along with similar ovens described below) were conveyor ovens.

[0093] The latex compound dip 130 step in this set of examples involved immersing the mold in a tank containing 3,800 liters of latex compound at 31°C for 10.7 seconds.

[0094] The latex compound contained 77.12 wt. % latex, 0.39 wt. % titanium metal, active zinc oxide, the characteristics and amounts of which are further set forth in Table 1 below, 0.35 wt. % zinc diethyldithiocarbamate (ZDEC), 0.23 wt. % zinc dibutyldithiocarbamate (ZDBC), 0.03 wt. % sodium dibutyldithiocarbamate (NaBDC), 0.85 wt. % sulfur (S8), 0.54 wt. % antioxidant, 0.12 wt. % potassium hydroxide (KOH), and 0.62 wt. % ammonia (NH3) preservatives, with the balance being calcium carbonate (CaCO3).

[0095] The latex compound coated former was then dried in an industrial oven at 90°C for 46.3 seconds and then sent to the beading 140 step.

[0096] Beading 240 for this set of examples was performed according to one embodiment previously described with respect to FIG. 2, followed by drying the former with the latex glove still deposited on it in a series of two industrial ovens at 124° C. and 119.2° C. for a total time of 11 seconds.

[0097] The leaching 250 steps in this set of examples were then carried out in three leaching tanks, each containing 3,050 liters of water at 90°C. The former with the latex glove remained in each leaching tank for 13.2 seconds. The leached latex gloves, still on the former, were then dried in a series of five ovens for a total time of 238.2 seconds at the following elevated temperatures: ambient temperature, 80°C, 120°C, 120°C, and 120°C.

[0098] The cuffing 260 step in this set of examples was performed according to one embodiment previously described with respect to FIG.

[0099] The latex gloves were then stripped from the formers according to a preferred embodiment of a stripping step 270. The formers were then returned to the step of preparing the formers 210 at the start of the method 200. The latex gloves so stripped were then sent to the step of offline chlorination treatment 280.

[0100] In the 280 offline chlorination steps, latex gloves were washed in the following order: (1) 10 minutes in water at ambient temperature, (2) 25 minutes in a chlorinating agent containing a mixture of 15% sodium hypochlorite (NaOCl) and 50% silicone (TSC 29.0-35.0%) by weight per volume of water at ambient temperature, (3) 15 minutes in water at ambient temperature, (4) another 15 minutes in water at ambient temperature, (5) 10 minutes in water at ambient temperature, and (6) another 10 minutes in water at ambient temperature. All of these washing steps were performed in a 1,500-liter offline (i.e., batch) tank, with the respective water / agents drained from the tank at the end of each wash step and filled back into the tank at the beginning of each wash step. Finally, the latex gloves were dried in a 125°C oven for 70 minutes and then allowed to cool to ambient temperature for 20 minutes.

[0101] The chlorinated latex gloves were collected for further testing and analysis of their zinc residue content and mechanical properties. For details of these tests and analyses, see Analysis of Latex Gloves Obtained from the Examples and Table 2 further below.

[0102] Third Set of Examples The third set of examples corresponds to Examples 9-13 in Table 1. They were carried out according to the exemplary embodiment of making powdered latex gloves described above in connection with FIG.

[0103] In the mold preparation 310 step of this set of examples, a mold made of a known ceramic was first washed for 7.8 seconds at 30°C in an acid tank containing 1,300 liters of an aqueous solution containing 1.0% by weight nitric acid (HNO3) per volume of water. Next, the mold was washed for 7.8 seconds in an alkaline tank containing 1,300 liters of an aqueous solution containing 1.0% by weight of a known alkaline cleaner per volume of water at 30°C. The mold was then washed with water in a series of two tanks, each for 5 seconds. Each tank contained 900 liters of water at a different temperature, with the first tank having a temperature of 84°C and the second tank having a temperature of 94°C. The mold was then removed from the water tank and dried in an oven at 106°C for 16.7 seconds.

[0104] In the coagulant dip 320 step in this set of examples, the formers were dipped into a tank containing 1,130 liters of an aqueous solution containing 6.0% by weight calcium carbonate (CaCO) and 4.5% by weight calcium nitrate (Ca(NO)) per volume of water at 78°C for 9.7 seconds. The formers were then dried in a series of industrial ovens at 115°C for 30.6 seconds until the water was substantially removed. In those examples involving continuous processes, the industrial ovens (along with similar ovens described below) were conveyor ovens.

[0105] The latex compound dip 330 step in this set of examples involved immersing the mold in a tank containing 4,100 liters of latex compound at 30°C for 20 seconds.

[0106] The latex compound contained 70.23 wt. % latex, active zinc oxide, the characteristics and amounts of which are further set forth in Table 1 below, 0.21 wt. % zinc diethyldithiocarbamate (ZDEC), 0.14 wt. % zinc dibutyldithiocarbamate (ZDBC), 0.48 wt. % sulfur (S8), 0.35 wt. % antioxidant, 0.05 wt. % preservative which was potassium hydroxide (KOH), 0.18 wt. % known antifoaming agent, and the balance calcium carbonate (CaCO3).

[0107] The latex compound coated mold was then dried in an industrial oven at 130° C. for 91.7 seconds and then sent to the beading 340 step.

[0108] Beading 340 in this set of examples was performed according to one embodiment previously described with respect to FIG. 1, followed by drying the mold with the latex glove still deposited on it in an industrial oven at 125° C. for 30.6 seconds.

[0109] The leaching 350 step in this set of examples was then carried out in four leaching tanks, each containing 2,000 liters of water. The latex gloved formers were held in a series of two pre-leaching tanks at 87°C for 16.7 seconds each. The formers were then dried in an intervening series of four ovens at 115°C, 125°C, 121°C, and 114°C for 91.7 seconds each. The latex gloved formers then exited the ovens and entered a series of two post-leaching tanks, each at 87°C, in which they were held for 9.7 and 22.2 seconds, respectively.

[0110] The former with the wet latex glove still deposited thereon then proceeded to the powdering 360 step, which was carried out in a 900 liter powdering tank at ambient temperature, in which the latex glove was immersed and exposed to a powdering medium that was a 4.0% by weight dispersion of corn starch powder per volume of water. The former with the latex glove was so immersed for 4.2 seconds and then removed from the powdering tank for the cuffing 370 step.

[0111] The cuffing 370 step in this set of examples was performed according to one embodiment described above with respect to FIG.

[0112] Finally, the latex gloves were stripped from the formers according to a preferred embodiment in stripping step 380. The formers were then returned to the beginning of method 300 in the step of preparing the former 310. The so-stripped latex gloves were dried in an oven at 95°C for 1,100 seconds and then retrieved for further testing and analysis of their zinc residue content and mechanical properties. See further below, Analysis of Latex Gloves from the Preferred Embodiments, and Table 2, for details of these tests and analyses.

[0113] Analysis of latex gloves obtained from the embodiment Subsequently, the latex gloves obtained from the above Examples 1 to 13 were analyzed for their zinc residue content according to the following three standards, namely BS EN1186-9:2002, BS EN13130-1:2004, and Articles 7 and 10 of the Food Sanitation Law No. 233 of Japan, and for their mechanical properties according to the following two standards, EN455-2:2015 and ISO11193-1:2020.

[0114] [Table 1]

[0115] The same analysis was performed on two comparative samples representing the state of the art, which are conventionally manufactured latex gloves, and the results are shown in Table 2 above.

[0116] Also, in Table 2, the heading "Mechanical Property Testing" is indicated by a superscript (1), which indicates that the test and analysis standards for those mechanical properties differ between each set of examples (and therefore between latex glove variants). The test standards are EN 455-2:2015 for powdered latex gloves unrelated to chlorination treatment, i.e., Examples 1-8, and ISO 11193-1:2020 for powdered latex gloves, i.e., Examples 9-13. The aging treatments associated with the mechanical property testing were performed according to either the EN 455-2:2015 or ISO 11193-1:2020 standard, as appropriate, at 70±2°C for 168±2 hours.

[0117] With regard to zinc residues, the control samples showed specific zinc migration of 10.0-18.3 mg / kg when tested under BS EN1186-9:2002 and BS EN13130-1:2004 standards, and extractable zinc of 6.9-14.7 μg / mL when tested under Articles 7 and 10 of the Japanese Food Sanitation Law No. 233.

[0118] In comparison, latex glove samples according to Examples 1-6 (representing process variations for producing powder-free latex gloves with online chlorination treatment) showed significantly lower specific zinc transfer levels of 2.8-4.7 mg / kg under BS EN1186-9:2002 and BS EN13130-1:2004 standards, and extractable zinc levels of 3.5-4.7 μg / mL when tested under Articles 7 and 10 of the Japanese Food Sanitation Law No. 233.

[0119] Furthermore, latex glove samples according to Examples 7-8 (representing a process variant for producing powder-free latex gloves with offline chlorination treatment) showed similarly low specific zinc transfer levels of 4.2-4.3 mg / kg under BS EN1186-9:2002 and BS EN13130-1:2004 standards, and extractable zinc levels of 4.2-4.3 μg / mL when tested under Articles 7 and 10 of the Japanese Food Sanitation Law No. 233.

[0120] Furthermore, the latex glove samples from Examples 9-13 (representing process variations for producing powdered latex gloves) showed similarly low extractable zinc levels of 4.0-6.0 μg / mL when tested under Articles 7 and 10 of the Japanese Food Sanitation Law No. 233. Test results for this set of samples under the BS EN 1186-9:2002 and BS EN 13130-1:2004 standards were not applicable. However, considering the results applicable for the samples from Examples 1-8, it can be reasonably assumed that if the samples from Examples 9-13 were tested under the BS EN 1186-9:2002 and BS EN 13130-1:2004 standards, the results would likely be significantly lower than those for the comparative samples and fall within a range significantly similar to those for the samples from Examples 1-8.

[0121] Furthermore, as can be seen from Table 2 when read in conjunction with Table 1, 6.0 to 6.5 m 2 The embodiments with activated zinc oxide having a BET specific surface area in the range of 1 / g, i.e., within the narrower, more preferred range, showed significantly less zinc residue detected than samples from other embodiments. According to Table 1, although Examples 1-9 and 13 include activated zinc oxide having a BET specific surface area in such a preferred range, the samples produced in these examples showed an average extractable zinc amount of 3.9 μg / mL when tested under Articles 7 and 10 of the Food Sanitation Law No. 233 of Japan. In comparison, the samples in the less preferred range (6.5 μg / mL) showed an average extractable zinc amount of 3.9 μg / mL. 2 / g exceeds 31.0m 2 Samples produced in Examples 10-12 with activated zinc oxide having a BET specific surface area of ​​5.2 μg / mL when tested under Articles 7 and 10 of the Food Sanitation Act, No. 233 of Japan (not exceeding 10 μg / g) exhibited an average extractable zinc amount of 5.2 μg / mL, which was significantly higher than the samples from Examples 1-9 and 13. More notably, even embodiments with BET specific surface areas in the less preferred range still clearly outperformed the comparative samples, which exhibited an average extractable zinc amount of 10.8 μg / mL when tested under Articles 7 and 10 of the Food Sanitation Act, No. 233 of Japan.

[0122] With regard to mechanical properties, as shown in Table 2, the latex glove samples according to Examples 1-13 exhibited significantly reduced zinc residue depending on the embodiment, but also showed little, if any, trade-off in mechanical properties compared to the comparative samples. In fact, many of the examples exhibited better mechanical properties than the comparative samples.

[0123] As shown by the analytical results, the method with or according to one embodiment and the resulting latex glove product show a surprising and significant improvement over latex gloves made according to the state of the art.

[0124] [Table 2]

Claims

1. A latex compound for use in a method of manufacturing latex gloves, comprising 0.07 to 0.20% by mass of active zinc oxide (ZnO), wherein the active zinc oxide has a BET specific surface area within the range of 6.0 to 31.0 m ２ / g, characterized in that it is a latex compound.

2. 10. The latex compound of claim 1, wherein the activated zinc oxide is the activator.

3. 3. The latex compound of claim 2, wherein the activated zinc oxide is the only activator.

4. 10. The latex compound of claim 1, further comprising a coagulant, an accelerator, and sulfur.

5. The coagulant is calcium carbonate (CaCO ３ ) and calcium stearate (C ３６ H ７０ CaO ４ 5. The latex compound of claim 4, wherein the polyisoprene is selected from the group consisting of hydroxypropyl methylcellulose, ...

6. 5. The latex compound of claim 4, wherein the accelerator is one or more dialkyldithiocarbamates.

7. The activated zinc oxide is 6.0 to 6.5 m ２ 10. The latex compound of claim 1, having a BET specific surface area in the range of 100 / g.

8. 10. The latex compound of claim 1, wherein the activated zinc oxide further has an adsorption average pore size in the range of 200 to 330 angstroms.

9. 10. The latex compound of claim 1, wherein the activated zinc oxide further has a particle size in the range of 1.5 to 3.0 micrometers.

10. A method for manufacturing a latex glove, comprising the steps of drying a mold coated with a latex compound, leaching the mold, and peeling the latex glove from the mold, wherein the latex compound contains 0.07 to 0.20% by mass of active zinc oxide (ZnO), and the active zinc oxide has a BET specific surface area within the range of 6.0 to 31.0 m ２ / g, characterized by the method.

11. 11. The method of claim 10, wherein the latex gloves are powder-free latex gloves, and the method further comprises the step of an on-line chlorination treatment of the type.

12. 12. The method of claim 11, wherein the latex compound comprises 0.12 to 0.20 wt. % of the activated zinc oxide.

13. The activated zinc oxide is 6.0 to 6.5 m ２ 13. The method of claim 12, wherein the sintered body has a BET specific surface area in the range of 1 / g.

14. 11. The method of claim 10, wherein the latex gloves are powder-free latex gloves, and the method further comprises the step of an off-line chlorination treatment of said type.

15. 15. The method of claim 14, wherein the latex compound comprises 0.13 to 0.17 wt. % of the activated zinc oxide.

16. The activated zinc oxide is 6.0 to 6.5 m ２ 16. The method of claim 15, wherein the sintered body has a BET specific surface area in the range of 1 / g.

17. 11. The method of claim 10, wherein the latex gloves are powdered latex gloves.

18. 18. The method of claim 17, wherein the latex compound comprises 0.07 to 0.17 wt. % of the activated zinc oxide.

19. The activated zinc oxide is 6.0 to 6.5 m ２ 19. The method of claim 18, wherein the sintered body has a BET specific surface area in the range of 1 / g.

20. 11. The method according to claim 10, wherein the obtained latex glove product exhibits a specific migration level of zinc content of not more than 5 mg / kg when measured according to BS EN1186-9:2002 or BS EN13130-1:2004 standards, or an extractable zinc content of not more than 6 μg / mL when measured according to a) Rubber utensils (excluding baby utensils) in Japanese Ministry of Health and Welfare Notification No. 370 concerning compliance with the provisions of Article 7 Paragraph 1 and Article 10 of the Food Sanitation Act of Japan (Act No. 233) and its amendments, Part III Section D.

21. A latex glove product obtained from the method of any one of claims 10 to 20.

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