Latex compound for manufacture of a latex glove, and process using said latex compound

Abstract

To address the problem of reducing zinc oxide residue on a latex glove product, an embodiment provides a latex compound for use in a process for manufacturing a latex glove. Said latex compound is characterized in comprising: 0.07 – 0.20 % by weight of active zinc oxide (ZnO). Further, said active zinc oxide has BET specific surface area within the range of 6.0 – 31.0 m2 / g.

Description

[0001] TITLE OF THE INVENTION

[0002] LATEX COMPOUND FOR MANUFACTURE OF A LATEX GLOVE, AND PROCESS USING SAID LATEX COMPOUND

[0003] FIELD OF THE INVENTION

[0004] The present disclosure relates to a process for producing a latex glove and the resulting latex glove product, particularly to a latex compound used in such process.

[0005] BACKGROUND OF THE INVENTION

[0006] In latex compounds for manufacturing latex gloves, zinc oxide, particularly zinc (II) oxide (ZnO), is conventionally added as an activator. The activator is essential to the rate of the latex’s vulcanization, which in turn promotes the glove’s mechanical properties that are desirable in use. Examples of prior arts describing such conventional use include the international patent publication No. WO20I9I73863AI.

[0007] Zinc oxide is also known for its antimicrobial effects, the notion of which is compatible with latex articles which usually find their use in medical and healthcare fields. An example of such use is described in the international patent publication No. WO2021262487A1. This prior art suggests using zinc oxide composite, comprising a core material (clay, talc, mica, silica, etc.) coated with active zinc oxide. Said zinc oxide composite is added to the latex compound formulation to impart antimicrobial effects upon a latex article.

[0008] In any case, the use of zinc oxide in the arts has led to zinc oxide residue, distributed on the surface of the latex glove products. The residue on the glove’s contacting surface is an important skin irritant and allergen. Many regulatory authorities have set out the standards limiting the contents of zinc oxide residue on the latex glove products. Examples of such standards include BS EN 1186-9:2002 and BS EN 13130-1:2004, along with the Japan Ministry of Health and Welfare Notice No.370 and its amendments Part III section D for the compliance of the provisions of paragraph 1 of Article 7 and Article 10 of Japan Food Sanitation Law (Law No. 233)- a) Rubber (except nursing utensil).

[0009] None of the above prior arts has addressed the problem of zinc residue or suggested a solution to control it. As such, there is a strong yet unfulfilled need to reduce the zinc oxide residue upon latex gloves. SUMMARY OF THE INVENTION

[0010] An object of the present invention is to provide a latex compound for producing a latex glove that is capable of addressing the above need, and thus effectively reduces the contents of zinc oxide residue in the final latex glove product.

[0011] In the first aspect, an embodiment is a latex compound for use in a process for manufacturing a latex glove, said latex compound being characterized in comprising: 0.07 - 0.20 % by weight of active zinc oxide (ZnO), said active zinc oxide having BET specific surface area within the range of 6.0 - 31.0 m2 / g.

[0012] The above object is achieved by using a latex compound of the above characteristics for production of latex gloves. The inventors believes that the active form promotes the zinc oxide’s intended utility (i.e., as an activator of vulcanization) in the latex compound, and thus promotes its decomposition which then reduces the residue. With further experiments, the inventors also found the above specific ranges of dosage (i.e., % by weight) and BET specific surface area of the active zinc oxide. Controlling said key parameters within said ranges reduced zinc oxide residue to a satisfactory level while ensuring that the latex was properly vulcanized. Thus, the products’ mechanical properties were not impacted. Full details of the confirming experiments will be described later on.

[0013] Preferably, the active zinc oxide is the sole activator in the latex compound. Formulating a latex compound having a combination of inert zinc oxide and active zinc oxide would not perform as effectively as a compound having active zinc oxide as the sole activator does.

[0014] In an embodiment, the latex compound further comprises: a coagulant, an accelerator, and sulfur. Preferably, said coagulant is selected from calcium carbonate (CaCCE) and calcium stearate (C36H?oCa04). Also preferably, said accelerator is one or more dialkyldithiocarbamate salt. In a more preferred embodiment, the accelerator is a combination of the following dialkyldithiocarbamate salts: sodium dibutyldithiocarbamate (NaBDC), zinc diethyldithiocarbamate (ZDEC), and zinc diethyl dithiocarbamate (ZDBC). Also preferably, said sulfur is elemental sulfur in the powder form. The appropriate dosages of said further ingredients will be described later on.

[0015] Preferably, the active zinc oxide has BET specific surface area within the range of 6.0 - 6.5 m2 / g. This range gave better results in terms of less zinc residue, while the latex glove’s mechanical properties remain unaffected. Preferably, the active zinc oxide also has the adsorption average pore diameter within the range of 200 - 300 angstroms (A).

[0016] Preferably, the active zinc oxide also has the particle size within the range of 1.5 - 3.0 micrometers (pm).

[0017] In the second aspect, an embodiment is a process for manufacturing a latex glove, comprising steps of: drying a former coated with a latex compound, leaching said former, and stripping the latex glove from said former, said process being characterized in that the latex compound comprises 0.07 - 0.20 % by weight of active zinc oxide (ZnO), said active zinc oxide having BET specific surface area within the range of 6.0 - 31.0 m2 / g.

[0018] The second aspect relates closely to the first aspect. The present inventors were able to confirm that the inventive concept underlying the first aspect was applicable to a conventional process for manufacturing a latex glove without needing a substantial change in the process. This compatibility with the existing processes reduces the cost of implementation and thus adds further to the invention’s advantages.

[0019] The present inventors further found the following process variants as compatible and within the concept of the present invention.

[0020] In one embodiment, the process is the above-mentioned process for manufacturing a latex glove, wherein the latex glove is a powder-free latex glove, and wherein the process further comprises a step of online chlorination of the former.

[0021] In another embodiment, the process is the above-mentioned process for manufacturing a latex glove, wherein the latex glove is a powder-free latex glove, and wherein the process further comprises a step of offline chlorination of the former.

[0022] In yet another embodiment, the process is the above-mentioned process for manufacturing a latex glove, wherein the latex glove is a powdered latex glove.

[0023] The present inventors also found the following subranges of the active zinc oxide’s dosage and specific surface area as imparting better results than the above-mentioned general ranges did.

[0024] In an embodiment where the latex glove is a powder-free latex glove, and wherein the process further comprises the step of online chlorination of the former, the latex compound preferably comprises 0.12 - 0.20 % by weight of said active zinc oxide. In an embodiment where the latex glove is a powder-free latex glove, and wherein the process further comprises the step of offline chlorination of the former, the latex compound preferably comprises 0.13 - 0.17 % by weight of said active zinc oxide.

[0025] In an embodiment where the latex glove is a powdered latex glove, the latex compound preferably comprises 0.07 - 0.17 % by weight of said active zinc oxide.

[0026] In any process variant, the active zinc oxide preferably has BET specific surface area within the range of 6.0 - 6.5 m2 / g.

[0027] A latex glove resulting from the second aspect exhibits no more than 5 mg / kg specific migration of zinc contents when measured in accordance with BS EN 1186-9:2002 or BS EN 13130-1:2004 standard, or exhibits no more than 6 pg / mL extractable zinc contents when measured in accordance with the Japan Ministry of Health and Welfare Notice No.370 and its amendments Part III section D for the compliance of the provisions of paragraph 1 of Article 7 and Article 10 of Japan Food Sanitation Law (Law No. 233)- a) Rubber (except nursing utensil). Full details of the confirming tests and measurements will be described later on.

[0028] In the third aspect, an embodiment is a latex glove product obtained from the process according to any embodiment of the second aspect.

[0029] BRIEF DESCRIPTION OF DRAWINGS

[0030] The principle of the present invention and its advantages will become apparent in the following description, taking into consideration the accompanying drawing in which:

[0031] FIG. 1 shows a schematic flowchart of a process according to an embodiment for manufacturing a powder-free latex glove with online chlorination.

[0032] FIG. 2 shows a schematic flowchart of a process according to an embodiment for manufacturing a powder-free latex glove with offline chlorination.

[0033] FIG. 3 shows a schematic flowchart of a process according to an embodiment for manufacturing a powdered latex glove.

[0034] DETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTION

[0035] It is to be understood that the following detailed description will be directed to embodiments, provided as examples for illustrating the concept of the present invention only. The present invention is in fact not limited to particular embodiments described, as such may, of course, vary. It is also to 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 this invention will be limited only by the appended claims.

[0036] The detailed description of the invention is divided into various sections only for the reader’s convenience and disclosure found in any section may be combined with that in another section.

[0037] Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skills in the art to which this invention belongs.

[0038] It must be noted that as used herein and in the appended claims, the singular forms “a”, “an”, and “the” include plural referents unless the context clearly dictates otherwise.

[0039] The term “about” when used before a numerical designation, e.g., dimensions, time, amount, and such other, including a range, indicates approximations which may vary by ( + ) or ( - ) 10 %, 5 % or 1 %, or any sub-range or sub-value there between.

[0040] “Comprising” or “comprises” is intended to mean that the compositions and methods include the recited elements, but not excluding others. “Consisting essentially of’ when used to define compositions and methods, shall mean excluding other elements of any essential significance to the combination for the stated purpose. Thus, a device or method consisting essentially of the elements as defined herein would not exclude other materials or steps that do not materially affect the basic and novel characteristic(s) of the claimed invention. “Consisting of’ shall mean excluding more than trace elements of other ingredients and substantial method steps. Embodiments defined by each of these transition terms are within the scope of this invention.

[0041] “Latex glove” refers to a glove made of natural latex and is to be distinguished from a glove made of synthetic latex, such as a nitrile glove or neoprene glove.

[0042] “Coagulating agent” or “coagulant” refers to a substance that is added to cause latex particles to aggregate onto the former in order to form a weak, water containing film (i.e. a wet gel). Exemplary coagulants include calcium nitrate, calcium chloride, and ammonium nitrate.

[0043] “Accelerator” refers to a chemical added into a rubber / latex compound in order to increase the speed of vulcanization. Exemplary accelerators include dithiocarbamates, such as zinc dibutyldithiocarbamate (ZDBC), zinc diethyldithiocarbamate (ZDEC), and sodium dibutyl dithiocarbamate (NaBDC). “Activator” refers to inorganic and organic chemicals used to activate the action of accelerators. These chemicals reduce the vulcanization time (cure time) by increasing the rate of vulcanization. Exemplary activators include zinc (II) oxide (ZnO).

[0044] “Antioxidant” refers to a substance that is added in order to extend the useful service life of a glove product by protecting it against an attack / degradation by oxygen (O2). Exemplary antioxidants include a compound having phenol or amine functional group.

[0045] “Preservative” refers to a chemical that is added to a rubber / latex compound in order to control the coagulation of rubber / latex particles, thereby stabilizing the compound during the maturation time. Exemplary preservatives include ammonia (NH3) and potassium hydroxide (KOH).

[0046] “Water” includes tap water, distilled or otherwise purified water, with or without impurities or additives such as detergent or water softener / hardener, so long as such consists essentially of water and is considered appropriate for the respective use in an industrial facility for manufacturing a medical -grade product. Said appropriateness may be determined by a person of normal skills in the relevant art.

[0047] The following part of Detailed Description shall explain the use of latex compound (embodiments according to the first aspect) in the processes for manufacturing (embodiments according to the second aspect) a latex glove (embodiments according to the second aspect). The description’s structure will follow the exemplary variants of the processes and the latex glove: First, a process for manufacturing a powder-free latex glove, wherein the chlorination of the former is carried out by online chlorination; second, a process for manufacturing a powder-free latex glove, wherein the chlorination of the former is carried out by offline chlorination; and third, a process for manufacturing powdered a latex glove. This is to make apparent that the concept of the present invention applies to any variant of said process.

[0048] Manufacture Of Powder-Free Latex Glove with Online Chlorination

[0049] Fig. 1 shows a schematic flowchart of a process according to an embodiment for manufacturing a powder-free latex glove with online chlorination. In this embodiment, a process for manufacturing a latex glove 100 comprises subcomponent steps of: preparing a former 110, coagulant dipping 120, latex compound dipping 130, beading 140, leaching 150, online chlorination 160, cuffing 170, and stripping 180. All the foregoing work steps are carried out continuously. In this embodiment, technical characteristics according to the concept of the present invention are embodied in connection with the step of latex compound dipping 130, which will be apparent in the later part of this Detailed Description. The overview of the process 100 afforded by Fig. 1 also shows that the concept of the present invention may be incorporated into an existing process in the arts with minimal complications.

[0050] In this embodiment, the process 100 starts with preparing the former 110. Said former means a mold embodying a shape of the intended glove products. The formers are normally positive molds which may be made of suitable metals or ceramics. Here, the former may be a clean one or that which has been returned from the step of stripping 180. In the preferred step of preparing the former 110, the former is washed with an acid aqueous solution containing 0.2 - 2.0 % weight of the acid compound per volume of water, at a temperature of 50 - 60 °C for 12 - 15 seconds. Said acid compound is preferably a strong acid, including hydrochloric acid (HC1) and nitric acid (HNO3). The former is then washed with an alkali aqueous solution, preferably twice: the first time with a first alkali aqueous solution containing 0.1 - 2.0 % weight of a known alkaline cleaning agent per volume of water, at a temperature of 60 - 70 °C for 8 - 12 seconds; and the second time with a second alkali aqueous solution containing 0.8 - 1.3 % weight of a known alkaline cleaning agent per volume of water (which may or may not be the same cleaning agent in the first alkali washing), at a temperature of 60 - 70 °C for another 8 - 12 seconds. Afterwards, the former is washed with water, preferably twice, each time at a temperature of 70 - 100 °C and for 8 - 12 seconds.

[0051] The next step of coagulant dipping 120 involves immersing the former obtained from the preparation step 110 in a coagulant. Here, the coagulant is an aqueous solution containing 2.0 - 5.0 % by weight of calcium stearate (C .FFoCaO-i) per volume of water as a primary coagulating agent and preferably 10.0 - 15.0 % by weight per volume of water of a secondary coagulating agent known in the arts. Said secondary coagulating agent is most preferably calcium nitrate (Ca NCh ). The immersion / dipping is preferably carried out at the coagulant’s temperature of 50 - 70 °C and for 12 - 15 seconds. Consequently, the former is covered with the coagulant before being dried at the temperature of 70 - 120 °C for 120 - 140 seconds. Said drying is preferably carried out in a closed space, preferably in an oven in order to prevent an interference by airborne contaminants, and more preferably in a series of ovens at gradually descending temperatures within the abovementioned general range. The process 100 then proceeds to the step of latex compound dipping 130.

[0052] In this embodiment, the step of latex compound dipping 130 involves immersing the former, already covered with a dry coagulant, into a latex compound. The coagulant induces deposition of latex particles onto the former in order to form a wet fdm which constitutes a primary body of the intended latex glove.

[0053] The latex compound in this preferred embodiment is formulated in accordance with the present invention’s characteristic technical concept. Particularly, said preferred latex compound consists essentially of: (i) 75 - 80 % by weight of latex; (ii) 0.5 - 0.7 % by weight of titanium metal; (iii) 0.07 - 0.20 % by weight, or more preferably 0. 12 - 0.20 % by weight, of active zinc oxide (ZnO), the preferred characteristics of which will be described further below; (iv) 0.2 - 0.4 % by weight of zinc diethyldithiocarbamate (ZDEC); (v) 0.15 - 0.25 % by weight of zinc dibutyldithiocarbamate (ZDBC); (vi) 0.01 - 0.05 % by weight of sodium dibutyldithiocarbamate (NaBDC); (vii) 0.4 -0.6 % by weight of sulfur (Ss); (viii) 0.4 - 0.6 % by weight of an antioxidant; (ix) 0.01 - 0.15 % by weight of one or more preservatives; and (x) balance of calcium carbonate (CaCCh). In this embodiment, the latex compound of said formulation may be prepared by a known means of mixing that is conventionally used for preparing liquid dispersion materials.

[0054] Preferably, said active zinc oxide (ZnO) has BET specific area within the range of 6.0 - 31.0 m2 / g, or more preferably within the range of 6.0 - 6.5 m2 / g. Also more preferably, said active zinc oxide also has the adsorption average pore diameter within the range of 200 - 330 angstroms and / or also has the particle size within the range of 1.5 - 3.0 micrometers.

[0055] In the step of latex compound dipping 130, the former is immersed in said latex compound at a temperature of 25 - 35 °C for 15 - 25 seconds. The former, thus coated with the wet latex compound with the effect of coagulant, is then dried at a temperature of 70 - 120 °C for 90 - 110 seconds. Said drying is preferably carried out in an oven for reasons similar to the above. The former thus coated in the dried latex compound film is subsequently forwarded to the next step of beading 140.

[0056] In this embodiment, the step of beading 140 involves rolling the open-ended sleeve of the latex glove, still being coated upon the former. Said rolling in this preferred embodiment is carried out by way of feeding the former into a sequence of brushes so that each of said brushes incrementally rolls the open end of the latex glove, thereby forming a round edge at said end. Further detail of the beading that is applicable to this embodiment may be found in the conventional arts. The step of beading 140 ends with drying the beaded latex glove at a temperature of 80 - 100 °C for 80 - 90 seconds, preferably in an oven for reasons similar to the above. In this embodiment, the next step of leaching 150 is carried out in order to remove residual chemicals from the latex glove, which is still being deposited on the former. Said leaching is carried out by dipping the former into water at a temperature of 40 - 90 °C for 60 - 90 seconds. Preferably, the leaching 150 is carried out in a series of tanks at gradually ascending temperatures within the abovementioned general range. The leached latex glove is then dried at a temperature of 75 - 90 °C for 850 - 900 seconds, preferably in an oven for reasons similar to the above, and more preferably in a series of ovens. After drying, the latex glove is then cooled at an ambient temperature for 40 - 60 seconds, preferably in a liquid cooling medium which preferably is water. Preferably, the cooling is carried out in a series of tanks.

[0057] Subsequently, the step of online chlorination 160 takes place directly and continuously after the above-described step of leaching 150. Although the concept of the present invention applies to any known chlorination agent, liquid or gas, in this exemplary embodiment the chlorination agent is chlorine gas (Ch). In a preferred embodiment, the online chlorination 160 is carried out in a closed chamber, wherein the latex glove is exposed to 600 - 1,200 ppm of chlorine gas at an ambient temperature for 30 - 40 seconds. Preferably, the latex glove leaving the chlorination chamber enters a neutralizing tank or a series thereof to control the chlorine gas residue or its derivative on the glove. In a preferred embodiment, a series of neutralizing tanks comprises a soak tank and a neutralizer tank, followed by three rinse tanks. In the soak tank, the latex glove is immersed in a liquid medium, preferably water, at an ambient temperature for 5 - 15 seconds. In the neutralizer tank, the latex glove is immersed at an ambient temperature for 5 - 15 seconds in a neutralizing agent, preferably an aqueous solution of a strong base, which in an exemplary embodiment is 0.1 % by weight of potassium hydroxide (KOH) in water. In an exemplary embodiment, the three rinse tanks contains water at different temperatures: the first tank at an ambient temperature; the second and third tanks at 65 - 80 °C. The latex glove is immersed in the rinse tanks for 30 - 45 seconds in total. Subsequently, the latex glove is dried at 55 - 65 °C for 150 - 200 seconds in an oven or a series thereof before being forwarded to the step of cuffing 170.

[0058] The step of cuffing 170 is preferably carried out by a means similar to the step of beading 140, sufficiently described above. Here, the former is also fed into a sequence of brushes so that each of said brushes incrementally rolls the open end of the latex glove. A main difference between the steps of beading 140 and cuffing 170 is the extent of rolling: the step of beading 140 is to roll the latex glove just sufficiently to form a round edge at the glove’s end; the step of cuffing 170 is to roll the glove further to the middle part thereof to facilitate the succeeding step of stripping 180. And the configurations of the relevant brushes and machine are adjusted in accord with the conventional knowledge to achieve said purpose.

[0059] The stripping step 180 follows in order to remove the latex glove, then adequately formed, treated and stable, from the former. In this preferred embodiment, the stripping step 180 may be carried out by any conventional means, though in this preferred embodiment it is carried out by gripping and pulling the latex glove from the former. At the end of the stripping step 180, the latex glove is forwarded to the storage and the blank former is returned to the step of preparing the former 110 which cleans and prepares the former for the next cycle from the step of coagulant dipping 120 through the step of stripping 180.

[0060] Manufacture Of Powder-Free Latex Glove with Offline Chlorination

[0061] Fig. 2 shows a schematic flowchart of a process according to an embodiment for manufacturing a powder-free latex glove with offline chlorination. In this embodiment, a process for manufacturing a latex glove 200 comprises subcomponent steps of: preparing a former 210, coagulant dipping 220, latex compound dipping 230, beading 240, leaching 250, cuffing 260, stripping 270, and offline chlorination 280. The foregoing steps are carried out continuously except the offline chlorination 280 which is a batch operation. One may appreciate that exemplary embodiments of an online-chlorination variant (100, Fig. 1) and of an offlinechlorination variant (200, Fig. 2) differ mainly in their order of their respective chlorination steps (160, 280), but such difference is not necessary and not the only difference between the two variants, as will be described further. In this embodiment, technical characteristics according to the concept of the present invention are also embodied in connection with the step of latex compound dipping 230, which will be apparent in the later part of this Detailed Description. The overview of the process 200 afforded by Fig. 2 also shows that the concept of the present invention may be incorporated into an existing process in the arts with minimal complications.

[0062] In this embodiment, the process 200 starts with preparing the former 210, further description of which follows the above-mentioned description regarding the step of preparing the former 110 shown in Fig. 1. Here, the former may be a clean one or that which has been returned from the step of stripping 270. In the preferred step of preparing the former 210, the former is washed with an acid aqueous solution containing 0.2 - 2.0 % weight of the acid compound per volume of water, at a temperature of 50 - 60 °C for 5 - 10 seconds. Said acid compound is preferably a strong acid, including hydrochloric acid (HC1) and nitric acid (HNO3). The former is then washed with an alkali aqueous solution containing 0.1 - 2.0 % weight of a known alkaline cleaning agent per volume of water, at a temperature of 60 - 70 °C for 2 - 8 seconds. Preferably, the former is further cleaned by brushing. Afterwards, the former is washed with water, preferably twice, each time at a temperature of 80 - 100 °C and for 2 - 8 seconds; and then is dried preferably in a closed space, such as in an oven, in order to prevent an interference by airborne contaminants. The drying temperature is preferably within 60 - 70 °C and drying time within 15 - 20 seconds.

[0063] The next step of coagulant dipping 220 involves immersing the former obtained from the preparation step 210 in a coagulant. Here, the coagulant is an aqueous solution containing 3.0 - 10.0 % by weight of calcium carbonate (CaCCh) per volume of water as a primary coagulating agent and preferably 4.0 - 12.0 % by weight per volume of water of a secondary coagulating agent known in the arts. Said secondary coagulating agent is most preferably calcium chloride (CaCh). The immersion / dipping is preferably carried out at the coagulant’s temperature of 70 - 90 °C and for 5 - 10 seconds. Consequently, the former is covered with the coagulant before being dried at the temperature of 70 - 130 °C for a total time of 30 - 40 seconds preferably in an oven, and more preferably in a series of ovens at gradually descending temperatures within the abovementioned general range. The process 200 then proceeds to the step of latex compound dipping 230.

[0064] Here, the role of coagulant, now coated and dried on the former, in the step of latex compound dipping 230 follows the above-mentioned description regarding the step of latex compound dipping 130 shown in Fig. 1.

[0065] The latex compound in this preferred embodiment is formulated in accordance with the present invention’s characteristic technical concept. Particularly, said preferred latex compound consists essentially of: (i) 75 - 80 % by weight of latex; (ii) 0.2 - 0.6 % by weight of titanium metal; (iii) 0.07 - 0.20 % by weight, or more preferably 0. 13 - 0.17 % by weight, of active zinc oxide (ZnO), the preferred characteristics of which will be described further below; (iv) 0.2 - 0.4 % by weight of zinc diethyldithiocarbamate (ZDEC); (v) 0.15 - 0.25 % by weight of zinc dibutyldithiocarbamate (ZDBC); (vi) 0.01 - 0.05 % by weight of sodium dibutyldithiocarbamate (NaBDC); (vii) 0.6 -0.8 % by weight of sulfur (Ss); (viii) 0.4 - 0.6 % by weight of an antioxidant; (ix) 0.10 - 0.90 % by weight of one or more preservatives; and (x) balance of calcium carbonate (CaCCh). In this embodiment, the latex compound of said formulation may be prepared by a known means of mixing that is conventionally used for preparing liquid dispersion materials. Preferably, said active zinc oxide (ZnO) has BET specific area within the range of 6.0 - 31.0 m2 / g, or more preferably within the range of 6.0 - 6.5 m2 / g. Also more preferably, said active zinc oxide also has the adsorption average pore diameter within the range of 200 - 330 angstroms and / or also has the particle size within the range of 1.5 - 3.0 micrometers.

[0066] In the step of latex compound dipping 230, the former is immersed in said latex compound at a temperature of 25 - 35 °C for 10 - 20 seconds. The former, thus coated with the wet latex compound with the effect of coagulant, is then dried at a temperature of 70 - 110 °C for 40 - 60 seconds. Said drying is preferably carried out in an oven for reasons similar to the above. The former thus coated in the dried latex compound film is subsequently forwarded to the next step of beading 240.

[0067] In this embodiment, the general description on the step of beading 240 follows the above- mentioned description regarding the step of beading 140 shown in Fig. 1. Here, the step of beading 240 ends with drying the beaded latex glove at a temperature of 110 - 125 °C for a total time of 10 - 15 seconds, preferably in an oven for reasons similar to the above, and more preferably in a series of ovens.

[0068] In this embodiment, the next step of leaching 250 is carried out in order to remove residual chemicals from the latex glove, which is still being deposited on the former. Said leaching is carried out by dipping the former into water at a temperature of 80 - 100 °C for 30 - 45 seconds. Preferably, the leaching 250 is carried out in a series of tanks at a temperature within the abovementioned general range. The leached latex glove is then dried at a temperature of 250 - 130 °C for a total time of 220 - 240 seconds, preferably in an oven for reasons similar to the above, and more preferably in a series of ovens at ascending temperatures within the said general range.

[0069] In this embodiment, the general descriptions on the step of cuffing 260 and stripping 270 follow the above-mentioned descriptions regarding the step of cuffing and stripping 170, 180 shown in Fig. 1, with a notable distinction: In the variant shown in Fig. 2, after the step of stripping 270 the latex glove is not yet forwarded to the storage; instead, the latex glove is forwarded to the step of offline chlorination 280.

[0070] Subsequently, the step of offline chlorination 280 takes place discontinuously after the above-described step of stripping 270. Although the concept of the present invention applies to any known chlorination agent, liquid or gas, in this exemplary embodiment the chlorination agent is a mixture of sodium hypochlorite (NaOCl) and silicone in water. The latex glove, now fully formed and stripped from the former, is first washed with water at an ambient temperature for 10 minutes. Then the glove is chlorinated by washing it for another 20 - 30 minutes with said chlorination agent, preferably a mixture of 10 - 20 % by weight of sodium hypochlorite and 45

[0071] - 55 % by weight of silicone (TSC 29.0 - 35.0 %) per volume of water. Afterwards, the glove may still contain chlorination residues which are further neutralized by washing the glove in water at an ambient temperature for 40 - 60 minutes. To promote a thorough neutralization, the glove is preferably washed a least four times within said total duration. More preferably, all the foregoing washings are carried out at an ambient temperature in the same vessel, from which at each washing’s end the respective water / agent is drained, and into which at each washing’s beginning the respective water / agent is filled. Finally, the latex glove is dried in an oven at 100

[0072] - 130 °C for 70 minutes before being left to cool down to the ambient temperature, and then forwarded to the storage.

[0073] Manufacture Of Powdered Latex Glove

[0074] Fig. 3 shows a schematic flowchart of a process according to an embodiment for manufacturing a powdered latex glove. In this embodiment, a process for manufacturing a latex glove 300 comprises subcomponent steps of: preparing a former 310, coagulant dipping 320, latex compound dipping 330, beading 340, leaching 350, powdering 360, cuffing 370, and stripping 380. The foregoing steps are carried out continuously. One may appreciate that exemplary embodiments of powder-free variants (100 and 200, Figs. 1 and 2) and of the variant for a powdered glove (300, Fig. 3) differ mainly in the inclusion or absence of a chlorination step (160, Fig. 1; 280, Fig. 2) and the powdering step (360, Fig. 3), but such difference is not the only difference between the variants, as will be described further. In this embodiment, technical characteristics according to the concept of the present invention are also embodied in connection with the step of latex compound dipping 330, which will be apparent in the later part of this Detailed Description. The overview of the process 300 afforded by Fig. 3 also shows that the concept of the present invention may be incorporated into an existing process in the arts with minimal complications.

[0075] In this embodiment, the process 300 starts with preparing the former 310, further description of which follows the above-mentioned description regarding the step of preparing the former 110 shown in Fig. 1. Here, the former may be a clean one or that which has been returned from the step of stripping 380. In the preferred step of preparing the former 310, the former is washed with an acid aqueous solution containing 0.2 - 2.0 % weight of the acid compound per volume of water, at a temperature of 25 - 40 °C for 5 - 10 seconds. Said acid compound is preferably a strong acid, including hydrochloric acid (HC1) and nitric acid (HNO3). The former is then washed with an alkali aqueous solution containing 0.1 - 2.0 % weight of a known alkaline cleaning agent per volume of water, at a temperature of 25 - 40 °C for 5 - 10 seconds. Afterwards, the former is washed with water, preferably twice, each time at a temperature of 80 - 100 °C and for 2 - 8 seconds; and then is dried preferably in a closed space, such as in an oven, in order to prevent an interference by airborne contaminants. The drying temperature is preferably within 90 - 120 °C and drying time within 15 - 20 seconds.

[0076] The next step of coagulant dipping 320 involves immersing the former obtained from the preparation step 310 in a coagulant. Here, the coagulant is an aqueous solution containing 3.0 - 10.0 % by weight of calcium carbonate (CaCOft per volume of water as a primary coagulating agent and preferably 4.0 - 10.0 % by weight per volume of water of a secondary coagulating agent known in the arts. Said secondary coagulating agent is most preferably calcium nitrate (CafNCh ). The immersion / dipping is preferably carried out at the coagulant’s temperature of 70 - 90 °C and for 5 - 10 seconds. Consequently, the former is covered with the coagulant before being dried at the temperature of 100 - 130 °C for 30 - 40 seconds preferably in an oven. The process 300 then proceeds to the step of latex compound dipping 330.

[0077] Here, the role of coagulant, now coated and dried on the former, in the step of latex compound dipping 330 follows the above-mentioned description regarding the step of latex compound dipping 130 shown in Fig. 1.

[0078] The latex compound in this preferred embodiment is formulated in accordance with the present invention’s characteristic technical concept. Particularly, said preferred latex compound consists essentially of: (i) 70 - 75 % by weight of latex; (ii) 0.07 - 0.20 % by weight, or more preferably 0.07 - 0.17 % by weight, of active zinc oxide (ZnO), the preferred characteristics of which will be described further below; (iii) 0.1 - 0.3 % by weight of zinc diethyldithiocarbamate (ZDEC); (iv) 0.10 - 0.20 % by weight of zinc dibutyldithiocarbamate (ZDBC); (v) 0.3 -0.6 % by weight of sulfur (Ss); (vi) 0.2 - 0.5 % by weight of an antioxidant; (vii) 0.01 - 0.50 % by weight of one or more preservatives; (viii) 0.15 - 0.25 % by weight of a known antifoaming agent; and (x) balance of calcium carbonate (CaCOft. In this embodiment, the latex compound of said formulation may be prepared by a known means of mixing that is conventionally used for preparing liquid dispersion materials. Preferably, said active zinc oxide (ZnO) has BET specific area within the range of 6.0 - 31.0 m2 / g, or more preferably within the range of 6.0 - 6.5 m2 / g. Also more preferably, said active zinc oxide also has the adsorption average pore diameter within the range of 200 - 330 angstroms and / or also has the particle size within the range of 1.5 - 3.0 micrometers.

[0079] In the step of latex compound dipping 330, the former is immersed in said latex compound at a temperature of 25 - 35 °C for 15 - 25 seconds. The former, thus coated with the wet latex compound with the effect of coagulant, is then dried at a temperature of 120 - 150 °C for 80 - 100 seconds. Said drying is preferably carried out in an oven for reasons similar to the above. The former thus coated in the dried latex compound film is subsequently forwarded to the next step of beading 340.

[0080] In this embodiment, the general description on the step of beading 340 follows the above- mentioned description regarding the step of beading 140 shown in Fig. 1. Here, the step of beading 340 ends with drying the beaded latex glove at a temperature of 120 - 140 °C for 25 - 35 seconds, preferably in an oven for reasons similar to the above.

[0081] In this embodiment, the next step of leaching 350 is carried out in order to remove residual chemicals from the latex glove, which is still being deposited on the former. Said leaching is carried out by dipping the former into water at a temperature of 70 - 100 °C for a total time of 60 - 80 seconds. Preferably, the leaching 350 is carried out in a series of tanks at a temperature within the abovementioned general range. More preferably, a series of four leaching is broken into two consecutive pre-leaching and then two consecutive post-leaching, interposed by drying at 100 - 140 °C for atotal time of 340 - 400 seconds and preferably in a series of four ovens. In this embodiment, the former and the deposited latex glove is not dried after the leaching (or in a preferred embodiment, after the final time of post-leaching) before being forwarded to the step of powdering 360.

[0082] Subsequently and continuously after the above-described step of leaching 350, the step of powdering 360 takes place. Although the concept of the present invention applies to any known powdering medium, in this exemplary embodiment the powdering medium is a dispersion of cornstarch powder in water, preferably prepared from 2.0 - 8.0 % by weight of cornstarch powder per volume of water. In a preferred embodiment, said powdering medium is provided at an ambient temperature. The former with the glove is immersed into said powdering medium for 3 - 8 seconds before being further forwarded to the step of cuffing 370. In this embodiment, the general descriptions on the step of cuffing 370 and stripping 380 follow the above-mentioned descriptions regarding the step of cuffing and stripping 170, 180 shown in Fig. 1, after which the latex glove is dried, preferably in an oven, at 80 - 120 °C for 900 - 1,200 seconds before being forwarded to the storage.

[0083] EXAMPLES OF EMBODIMENTS

[0084] Processes in accordance with the above-described embodiments were run according to the below description and to the particulars shown in Table 1 further below.

[0085] The First Set of Examples

[0086] The first set of Examples corresponds to Example Nos. 1 - 6 in Table 1. They were run in accordance with an exemplary embodiment of the Manufacture of Powder-Free Latex Glove with Online Chlorination, described previously in connection with Fig. 1.

[0087] In the step of preparing the former 110 in this set of Examples, the former, which was made of known ceramics, was first washed in an acid tank containing 3,200 liters of an aqueous solution comprising 1.0 % by weight of nitric acid (HNO3) per volume ofwater at 55 °C for 13.6 seconds. Next, the former was washed in two alkali tanks for 10 seconds in each. Each alkali tank contained, at 65 °C, 4,600 liters of an aqueous solution of a known alkaline cleaning agent. Both alkali tanks contained the same alkaline cleaning agent, though prepared at different concentrations: in the first alkali tank the concentration was 0.8 % weight of the cleaning agent per volume of water; and in the second alkali tank, 1.0 % weight of the cleaning agent per volume of water. Afterwards, the former was washed with water in a series of two tanks for 10 seconds in each. Each tank contained 4,700 liters of water at different temperatures: in the first tank the temperature was 80 °C; and in the second tank, 85 °C.

[0088] In the step of coagulant dipping 120 in this set of Examples, the former was dipped into a tank containing 8,500 liters of an aqueous solution comprising 12.0 % by weight of calcium nitrate (Ca NCE ) and 3.2 % by weight of calcium stearate (C .FEoCaO-i) per volume of water at 56 °C for 13.5 seconds. The former was then dried in a series of two industrial ovens, for 65 seconds in each, at 115 °C for in the first oven; and at 80 °C in the second oven, until water was effectively removed. In these Examples which involved a continuous process, said industrial ovens (along with similar ovens to be later described) were conveyor ovens.

[0089] In the step of latex compound dipping 130 in this set of Examples, the former was immersed in a tank containing 9,500 liters of the latex compound at 30 °C for 21 seconds. Said latex compound comprised: 77.64 % by weight of latex; 0.62 % by weight of titanium metal; active zinc oxide, the characteristics and amount of which shall be apparent further below in Table 1; 0.31 % by weight of zinc diethyldithiocarbamate (ZD EC); 0.23 % by weight of zinc dibutyldithiocarbamate (ZDBC); 0.01 % by weight of sodium dibutyldithiocarbamate (NaBDC); 0.54 % by weight of sulfur (Ss); 0.54 % by weight of an antioxidant; preservatives, which were 0.11 % potassium hydroxide (KOH) and 0.03 % ammonia (NH3); and balance of calcium carbonate (CaCOs).

[0090] Subsequently, the former coated with said latex compound was dried in an industrial oven at 105 °C for 103.5 seconds, before it was forwarded to the step of beading 140.

[0091] The beading 140 in this set of Examples was carried out according to an embodiment described previously in regard to Fig. 1; following which the former and the latex glove, still deposited upon the former, was dried in an industrial oven at 85 °C for 87 seconds.

[0092] Next, in the step of leaching 150 in this set of Examples was carried out in six leaching tanks, each containing 6,700 liters of water. In each leaching tank, the former and the latex glove was retained for 14.5 seconds. The temperatures in the leaching tanks were set as follows, respectively from the first to the sixth leaching tank into which the former and the latex glove entered: 45, 70, 75, 75, 80, and 80 °C. The leached latex glove, still on the former, was then dried in a series of six ovens at a constant 85 °C and for 872 seconds throughout the six ovens. The latex glove was then cooled in four tanks, each containing 6,400 liters of water at an ambient temperature, for 13.5 seconds in each tank.

[0093] The former, upon which the latex glove was still deposited, was then proceeded to the step of online chlorination 160. This step took place in a 16,500-liter online (i.e., continuous) chlorination chamber in which the latex glove was exposed to 900 ppm of chlorine gas (Ch) at an ambient temperature for 36.5 seconds. Afterwards, the former and latex glove entered a series of neutralizing tanks, namely a 4,000-liter soak tank, a 4,800-liter neutralizer tank, and one 4,800-liter ambient rinse tank followed by two 6,700-liter hot rinse tanks. The latex glove was immersed in water contained in said soak tank at an ambient temperature for 8 seconds; then in 0.1 % by weight of potassium hydroxide (KOH) in water contained in said neutralizer tank at an ambient temperature for 10 seconds; then in water contained in said ambient rinse tank at an ambient temperature for 10 seconds; and then in water contained in said hot rinse tanks at 70 °C for 14.5 seconds in each hot rinse tank. The rinsed latex glove on the former was then dried in an industrial oven at 660 °C for 169 seconds. The step of cuffing 170 in this set of Examples was carried out according to an embodiment described previously in regard to Fig. 1.

[0094] Finally, the latex glove was stripped from the former according to a preferred embodiment of the stripping step 180. The former was then returned to the step of preparing the former 110 at the beginning of the process 100. The latex glove stripped thus was collected for further tests and analyses for its zinc residue contents and mechanical properties. For detail of these tests and analyses, see Analyses of Latex Gloves Resulted from Embodiments and Table 2, further below.

[0095] The Second Set of Examples

[0096] The second set of Examples corresponds to Example Nos. 7 - 8 in Table 1. They were run in accordance with an exemplary embodiment of the Manufacture of Powder-Free Latex Glove with Offline Chlorination, described previously in connection with Fig. 2.

[0097] In the step of preparing the former 210 in this set of Examples, the former, which was made of known ceramics, was first washed in an acid tank containing 1,500 liters of an aqueous solution comprising 1.0 % by weight of nitric acid (HNO3) per volume of water at 55 °C for 5.5 seconds. Next, the former was washed for 10 seconds in an alkali tank containing, at 65 °C, 850 liters of an aqueous solution of 0.5 % weight of a known alkaline cleaning agent per volume of water. Afterwards, the former was washed with brushes and then washed in water in a series of two tanks, both containing 1,700 liters of water at 94 °C, for 6.6 seconds in the first tank and for 4.4 seconds in the second tank. Thereafter, the former is dried in an oven at 65 °C for 15.5 seconds.

[0098] In the step of coagulant dipping 220 in this set of Examples, the former was dipped into a tank containing 1,700 liters of an aqueous solution comprising 7.0 % by weight of calcium chloride (CaCh) and 4.0 % by weight of calcium carbonate (CaCOft per volume of water at 75 °C for 5.5 seconds. The former was then dried in a series of two industrial ovens, for 19.8 seconds in each, at 115 °C for in the first oven; and at 85 °C in the second oven, until water was effectively removed. In these Examples which involved a semi -continuous process, said industrial ovens (along with similar ovens to be later described) were conveyor ovens.

[0099] In the step of latex compound dipping 130 in this set of Examples, the former was immersed in a tank containing 3,800 liters of the latex compound at 31 °C for 10.7 seconds.

[0100] Said latex compound comprised: 77.12 % by weight of latex; 0.39 % by weight of titanium metal; active zinc oxide, the characteristics and amount of which shall be apparent further below in Table 1; 0.35 % by weight of zinc diethyldithiocarbamate (ZD EC); 0.23 % by weight of zinc dibutyldithiocarbamate (ZDBC); 0.03 % by weight of sodium dibutyldithiocarbamate (NaBDC); 0.85 % by weight of sulfur (Ss); 0.54 % by weight of an antioxidant; preservatives, which were 0.12 % by weight of potassium hydroxide (KOH) and 0.62 % by weight of ammonia (NH3); and balance of calcium carbonate (CaCO?).

[0101] Subsequently, the former coated with said latex compound was dried in an industrial oven at 90 °C for 46.3 seconds, before it was forwarded to the step of beading 140.

[0102] The beading 240 in this set of Examples was carried out according to an embodiment described previously in regard to Fig. 2; following which the former and the latex glove, still deposited upon the former, was dried for a total time of 11 seconds in a series of two industrial ovens, at 124 °C and at 119.2 °C.

[0103] Next, in the step of leaching 250 in this set of Examples was carried out in three leaching tanks, each containing 3,050 liters of water at 90 °C. In each leaching tank, the former and the latex glove was retained for 13.2 seconds. The leached latex glove, still on the former, was then dried in a series of five ovens for a total time of 238.2 seconds at the following ascending temperatures: an ambient temperature, 80 °C, 120 °C, 120 °C, and 120 °C.

[0104] The step of cuffing 260 in this set of Examples was carried out according to an embodiment described previously in regard to Fig. 2.

[0105] Subsequently, the latex glove was stripped from the former according to a preferred embodiment of the stripping step 270. The former was then returned to the step of preparing the former 210 at the beginning of the process 200. The latex glove stripped thus was then forwarded to the step of offline chlorination 280.

[0106] In the step of offline chlorination 280 step, the latex glove was washed in the following order: (1) with water at an ambient temperature for 10 minutes; (2) with a chlorination agent which was a mixture of 15 % by weight of sodium hypochlorite (NaOCl) and 50 % by weight of silicone (TSC 29.0 - 35.0 %) per volume of water at an ambient temperature for 25 minutes; (3) with water at an ambient temperature for 15 minutes; (4) with water at an ambient temperature for another 15 minutes; (5) with water at an ambient temperature for 10 minutes; and (6) with water at an ambient temperature for another 10 minutes. All the foregoing washings took place in a 1,500-liter offline (i.e., batch) tank, from which at each washing’s end the respective water / agent is drained, and into which at each washing’s beginning the respective water / agent is filled. Finally, the latex glove was dried in an oven at 125 °C for 70 minutes before being left to cool down to the ambient temperature for 20 minutes.

[0107] The latex glove chlorinated thus was collected for further tests and analyses for its zinc residue contents and mechanical properties. For detail of these tests and analyses, see Analyses of Latex Gloves Resulted from Embodiments and Table 2, further below.

[0108] The Third Set of Examples

[0109] The third set of Examples corresponds to Example Nos. 9 - 13 in Table 1. They were run in accordance with an exemplary embodiment of the Manufacture of Powdered Latex Glove, described previously in connection with Fig. 3.

[0110] In the step of preparing the former 310 in this set of Examples, the former, which was made of known ceramics, was first washed for 7.8 seconds in an acid tank containing, at 30 °C, 1,300 liters of an aqueous solution comprising 1.0 %by weight of nitric acid (HNO3) pervolume of water. Next, the former was washed for 7.8 seconds in an alkali tank containing, at 30 °C, 1,300 liters of an aqueous solution comprising 1.0 % by weight of a known alkaline cleaning agent per volume of water. Afterwards, the former was washed with water in a series of two tanks for 5 seconds in each. Each tank contained 900 liters of water at different temperatures: in the first tank the temperature was 84 °C; and in the second tank, 94 °C. The former then left the water tanks and was dried in an oven at 106 °C for 16.7 seconds.

[0111] In the step of coagulant dipping 320 in this set of Examples, the former was dipped into a tank containing 1,130 liter of an aqueous solution comprising 6.0 % by weight of calcium carbonate (CaCOft and 4.5 % by weight of calcium nitrate (CafNCh ) per volume of water at 78 °C for 9.7 seconds. The former was then dried in a series of an industrial oven at 115 °C for 30.6 seconds until water was effectively removed. In these Examples which involved a continuous process, said industrial oven (along with similar ovens to be later described) was a conveyor oven.

[0112] In the step of latex compound dipping 330 in this set of Examples, the former was immersed in a tank containing 4, 100 liters of the latex compound at 30 °C for 20 seconds.

[0113] Said latex compound comprised: 70.23 % by weight of latex; active zinc oxide, the characteristics and amount of which shall be apparent further below in Table 1 ; 0.21 % by weight of zinc diethyldithiocarbamate (ZDEC); 0.14 % by weight of zinc dibutyldithiocarbamate (ZDBC); 0.48 % by weight of sulfur (Ss); 0.35 % by weight of an antioxidant; 0.05 % by weight of a preservative which was potassium hydroxide (KOH); 0.18 % by weight of a known antifoaming agent; and balance of calcium carbonate (CaCOft.

[0114] Subsequently, the former coated with said latex compound was dried in an industrial oven at 130 °C for 91.7 seconds, before it was forwarded to the step of beading 340.

[0115] The beading 340 in this set of Examples was carried out according to an embodiment described previously in regard to Fig. 1; following which the former and the latex glove, still deposited upon the former, was dried in an industrial oven at 125 °C for 30.6 seconds.

[0116] Next, in the step of leaching 350 in this set of Examples was carried out in four leaching tanks, each containing 2,000 liters of water. The former and the latex glove was retained in a series of two pre-leaching tanks, each at 87 °C and for 16.7 seconds. Then it was dried in an interposing series of four ovens, each for 91.7 seconds and at 115, 125, 121, and 114 °C respectively. The former and the latex glove then left the ovens and entered a series of two postleaching tanks, each at 87 °C, and retained therein for 9.7 seconds and 22.2 seconds respectively.

[0117] The former, upon which the wet latex glove was still deposited, was then proceeded to the step of powdering 360. This step took place at an ambient temperature in a 900-liter powering tank in which the latex glove was immersed and exposed to a powdering medium, which was a dispersion of 4.0 % by weight of cornstarch powder per volume of water. The former and the latex glove was thus immersed for 4.2 seconds before leaving the powering tank for the step of cuffing 370.

[0118] The step of cuffing 370 in this set of Examples was carried out according to an embodiment described previously in regard to Fig. 3.

[0119] Finally, the latex glove was stripped from the former according to a preferred embodiment of the stripping step 380. The former was then returned to the step of preparing the former 310 at the beginning of the process 300. The latex glove stripped thus was dried in an oven at 95 °C for 1,100 seconds before being collected for further tests and analyses for its zinc residue contents and mechanical properties. For detail of these tests and analyses, see Analyses of Latex Gloves Resulted from Embodiments and Table 2, further below.

[0120] ANALYSES OF LATEX GLOVES RESULTED FROM EMBODIMENTS

[0121] The latex gloves resulting from the above Examples 1 - 13 were subsequently analyzed for their zinc residue contents according to the following three standards BS EN 1186-9:2002, BS EN 13130-1:2004, and Articles 7 and 10 of Japan Law No. 233; and for their mechanical properties according to the following two standards: EN 455-2:2015 and ISO 11193-1:2020.

[0122]

[0123] Same analyses were also run for two Comparative Samples, which represented the state of the art: the Comparative Samples were latex gloves manufactured in accordance with conventional processes. The results are shown in the above Table 2.

[0124] Table 2 at the heading of “Test of Mechanical Properties” also indicates a superscripted (1) which remarks the different standards by which different sets of Examples (and thus different variants of latex glove) were tested and analyzed for their same mechanical properties. Said test standards were EN 455-2:2015, applicable to powder-free latex gloves irrespective of their chlorination method, and thus to Examples 1 - 8; and ISO 11193-1:2020, applicable to powdered latex gloves and thus to Examples 9 - 13. The aging process associated with the tests of mechanical properties was carried out at 70 ± 2 °C for 168 ± 2 hours according to the EN 455- 2:2015 or ISO 11193-1:2020 standard, as the case may be.

[0125] Regarding the zinc residues, the Comparable Samples exhibited 10.0 - 18.3 mg / kg specific zinc migration when tested under BS EN 1186-9:2002 and BS EN 13130-1:2004 standards, and 6.9 - 14.7 pg / mL extractable zinc when tested under Articles 7 and 10 of Japan Law No. 233.

[0126] In comparison, latex glove samples from Examples 1 - 6 (representing the process variant for manufacturing powder-free latex gloves with online chlorination) exhibited remarkably low 2.8 - 4.7 mg / kg specific zinc migration under BS EN 1186-9:2002 and BS EN 13130-1:2004 standards, and 3.5 - 4.7 pg / mL extractable zinc when tested under Articles 7 and 10 of Japan Law No. 233.

[0127] Further, latex glove samples from Examples 7 - 8 (representing the process variant for manufacturing powder-free latex gloves with offline chlorination) exhibited similarly low 4.2 - 4.3 mg / kg specific zinc migration under BS EN 1186-9:2002 and BS EN 13130-1:2004 standards, and 4.2 - 4.3 pg / mL extractable zinc when tested under Articles 7 and 10 of Japan Law No. 233.

[0128] Furthermore, latex glove samples from Examples 9 - 13 (representing the process variant for manufacturing powdered latex gloves) exhibited similarly low 4.0 - 6.0 pg / mL extractable zinc when tested under Articles 7 and 10 of Japan Law No. 233. The test results under BS EN 1186-9:2002 and BS EN 13130-1:2004 standards were unavailable for this set of samples. However, considering the results available for samples from Examples 1 - 8, it may be fairly estimated that if the samples from Examples 9 - 13 were tested under BS EN 1186-9:2002 and BS EN 13130-1:2004 standards, the results would very probably fall within a range that is substantially lower than the results from Comparative Samples and substantially similar to the results from samples originated from Examples 1 - 8.

[0129] Even further, it is apparent from Table 2 when read jointly with Table 1 that embodiments involving active zinc oxide having BET specific surface areas in the range of 6.0 - 6.5 m2 / g — a narrower and more preferred range — exhibited a significantly lower detection of zinc residue than did samples from the other embodiments. From Table 1, Examples 1 - 9 and 13 involved active zinc oxide having BET specific surface areas in such preferred range; those Examples produced samples exhibiting a mean extractable zinc of 3.9 pg / mL when tested under Articles 7 and 10 of Japan Law No. 233. In comparison, Examples 10 - 12 which involved active zinc oxide having BET specific surface areas in a less preferred range (more than 6.5 and not exceeding 31.0 m2 / g) produced samples exhibiting a mean extractable zinc of 5.2 pg / mL, which was significantly higher than samples from Examples 1 - 9 and 13, when tested under Articles 7 and 10 of Japan Law No. 233. It should be further noted that even for embodiments involving a less preferred range of BET specific surface areas still clearly outperformed the Comparative Samples, which exhibited a mean extractable zinc of 10.8 pg / mL when tested under Articles 7 and 10 of Japan Law No. 233.

[0130] Regarding the mechanical properties, Table 2 shows that the latex glove samples from Examples 1 - 13, on which the zinc residues were greatly reduced in accordance with embodiments, also exhibited little to no trade-off in their mechanical properties when compared with the Comparative Samples. Indeed, many of the Examples exhibited superior mechanical properties over the Comparative Samples.

[0131] Said analytical results show that processes involving, or in accordance with, an embodiment and latex glove products resulting therefrom exhibited results which were distinctly and surprisingly improved over the latex gloves manufactured in accordance with the state of the art.

[0132]

Claims

CLAIMS A latex compound for use in a process for manufacturing a latex glove, said latex compound being characterized in comprising: 0.07 - 0.20 % by weight of active zinc oxide (ZnO), said active zinc oxide having BET specific surface area within the range of 6.0 - 31.0 m2 / g. The latex compound of claim 1, wherein the active zinc oxide is an activator. The latex compound of claim 2, wherein the active zinc oxide is the sole activator. The latex compound of claim 1, further comprising: a coagulant, an accelerator, and sulfur. The latex compound of claim 4, wherein the coagulant is selected from calcium carbonate (CaCCh) and calcium stearate (C .FhoCaO-i). The latex compound of claim 4, wherein the accelerator is one or more dialkyldithiocarbamate salt. The latex compound of claim 1, wherein the active zinc oxide has BET specific surface area within the range of 6.0 - 6.5 m2 / g. The latex compound of claim 1 , wherein the active zinc oxide also has the adsorption average pore diameter within the range of 200 - 330 angstroms. The latex compound of claim 1, wherein the active zinc oxide also has the particle size within the range of 1.5 - 3.0 micrometers. A process for manufacturing a latex glove, comprising steps of: drying a former coated with a latex compound, leaching said former, and stripping the latex glove from said former, said process being characterized in that the latex compound comprises 0.07 - 0.20 % by weight of active zinc oxide (ZnO), said active zinc oxide having BET specific surface area within the range of 6.0 - 31.0 m2 / g. The process of claim 10, wherein the latex glove is a powder-free latex glove, and wherein the process further comprises a step of online chlorination of the former. The process of claim 11, wherein the latex compound comprises 0. 12 - 0.20 % by weight of said active zinc oxide. The process of claim 12, wherein said active zinc oxide has BET specific surface area within the range of 6.0 - 6.5 m2 / g.The process of claim 10, wherein the latex glove is a powder-free latex glove, and wherein the process further comprises a step of offline chlorination of the former. The process of claim 14, wherein the latex compound comprises 0. 13 - 0.17 % by weight of said active zinc oxide. The process of claim 15, wherein said active zinc oxide has BET specific surface area within the range of 6.0 - 6.5 m2 / g. The process of claim 10, wherein the latex glove is a powdered latex glove. The process of claim 17, wherein the latex compound comprises 0.07 - 0.17 % by weight of said active zinc oxide. The process of claim 18, wherein said active zinc oxide has BET specific surface area within the range of 6.0 - 6.5 m2 / g. The process of claim 10, wherein the resulting latex glove product exhibits no more than 5 mg / kg specific migration of zinc contents when measured in accordance with BS EN 1186- 9:2002 or BS EN 13130-1:2004 standard, or exhibits no more than 6 pg / mL extractable zinc contents when measured in accordance with the Japan Ministry of Health and Welfare Notice No.370 and its amendments Part III section D for the compliance of the provisions of paragraph 1 of Article 7 and Article 10 of Japan Food Sanitation Law (Law No. 233)- a) Rubber (except nursing utensil). A latex glove product obtained from the process according to any one of claims 10 - 20.

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