SYNTHETIC POLYISOPRENE LATEX CONDOMS WITH REDUCED NITROSAMINE

Abstract

A synthetic polyisoprene latex emulsion has pre-vulcanization composition and post vulcanization composition. The pre-vulcanization composition comprises insoluble amorphous sulfur extracted with zinc dithiocarbamate catalyst at 20° C. to form sulfur chain and transported to interior of synthetic polyisoprene particle forming physical attachment of sulfur to active sites. The degree of pre-vulcanization is verified by expansion of cast and dried film of latex in toluene in 20 minutes by means of a swelling index test. The latex emulsion is vulcanized at 90° C. to 120° C. for 3 to 5 minutes. Post-vulcanization composition with accelerators crosslink between synthetic polyisoprene particles, uniformly curing both in the inter-particle and intra-particle regions to produce high cross link density, uniform distribution of double bonds with zinc segregation at the boundaries of original particles. The condom exhibits high tensile strength, tensile modulus, elongation with excellent tear strength releasing below 10 ppb of nitrosamines.

Claims

1. A highly stretchable tear resistant synthetic polyisoprene latex condom article comprising: a. said condom releasing low or no nitrosamine to a user wearing said condom or during manufacturing process preventing exposure of workers to carcinogens; b. said manufacturing process with synthetic polyisoprene latex mixed with combination of accelerators consisting of Zinc diethydithicarbamate (ZDEC), Zinc dibenzyoldithiocarbamate (ZBEC) and Zinc dibutyldithiocarbamate (ZDBC) and surfactants comprising 15% Hostapur anionic surfactant added and mixed for 12 hours at a temperature of 20° C. to 40° C.; c. synthetic polyisoprene particles in said latex that are pre-vulcanized by the addition of amorphous sulfur catalytically broken down by ZDBC catalyst one sulfur atom at a time to form chains of sulfur, and said sulfur chains transported using Hostapur SAS and other surfactants into interior spaces of synthetic polyisoprene latex particles; d. said incorporation of sulfur chains into interior of synthetic polyisoprene particles in the latex bath at temperature in the range of 20° C. to 40° C. occurring in a period of 1 minute to 12 hours forming physical attachment of sulfur from the transported chain of sulfur to active sites in the synthetic polyisoprene molecule forming pre-vulcanization of the synthetic latex particle; e. when all active sites in the interior of the synthetic latex are exhausted, more sulfur extracted by remaining ZDBC and other accelerators and transported to the exterior of said synthetic polyisoprene particle using Hostapur SAS and other surfactants thereby pre-vulcanizing all the synthetic polyisoprene particles; f. the pre-vulcanization status of the synthetic polyisoprene latex is determined by casting a film of the latex, drying it and cutting a disk of known diameter and immersing in toluene for 20 minutes per swelling index test protocol and examining the increase in diameter of the disk and when this increase is 130% of the cut diameter, the latex is ready for dipping condoms; g. several condom formers dipped in pre-vulcanized synthetic polyisoprene latex which is controlled at 20 to 30° C. and cured at 90 to 120° C. for 5 to 20 minutes forming cured latex condoms in a continuous production line. whereby said synthetic polyisoprene latex condom has high strength and is highly stretchable and does not release nitrosamine to condom user or at the manufacturing location.

2. The synthetic polyisoprene latex article of claim 1, wherein said synthetic polyisoprene latex condom with a width of 49 mm to 60 mm and a length of minimum 160mm with a thickness of 0.045 mm to 0.090 mm.

3. The synthetic polyisoprene latex article of claim 1, wherein said synthetic polyisoprene latex condom has a burst volume greater than 22 liters, and burst pressure of greater than 1 kPa.

4. The synthetic polyisoprene latex article of claim 1 said condom manufactured by dipping a latex condom in low temperature pre-vulcanized latex with a combination of accelerators including zinc oxide activator, ZDEC accelerator, ZBEC accelerator and ZDBC accelerator and vulcanized only at low temperature of between 90° C. and 120° C. producing no nitrosamine.

5. A method for manufacturing synthetic polyisoprene condom wherein sulfur for pre-vulcanization of synthetic condoms is provided in the form amorphous sulfur, which is insoluble in synthetic latex at processing temperature of 20° C. to 40° C. and is extracted as individual atom of sulfur in the four atom Zinc dibutyldithiocarbamate (ZDBC) catalyst ring and is transported to assemble a sulfur chain and transported by surfactant into the interior of polyisoprene particle thereby physically attaching sulfur at active sites in the synthetic polyisoprene molecule thus pre-vulcanizing the polyisoprene particle.

6. The method for manufacturing synthetic polyisoprene condom according to claim 5 wherein said pre-vulcanization composition accelerators selected from the group consisting Zinc diethydithicarbamate (ZDEC); accelerator, Zinc dibenzyoldithiocarbamate (ZBEC); accelerator, ZDBC; and accelerator and combinations thereof.

7. The method for manufacturing synthetic polyisoprene condom according to claim 5 wherein said surfactant comprises Hostapur SAS anionic surfactant, potassium caprylate, polyoxyethylene cetyl/stearyl ether, alkyl aryl sulphonate, alkyl sulphonate , olefin sulphonate, an alcohol sulphate or and combinations thereof.

8. A method for producing synthetic polyisoprene probe covers wherein sulfur for pre-vulcanization of synthetic probe covers is provided in the form amorphous sulfur, which is insoluble in synthetic latex at processing temperature of 20° C. to 40° C. and is extracted as individual atom of sulfur in the four atom Zinc dibutyldithiocarbamate (ZDBC) catalyst ring and is transported to assemble a sulfur chain and transported by surfactant into the interior of polyisoprene particle thereby physically attaching sulfur at active sites in the synthetic polyisoprene molecule thus pre-vulcanizing the polyisoprene particle.

9. The method for manufacturing synthetic polyisoprene probe cover according to claim 8 wherein said surfactant comprises Hostapur SAS anionic surfactant, potassium caprylate, polyoxyethylene cetyl/stearyl ether, alkyl aryl sulphonate, alkyl sulphonate , olefin sulphonate, an alcohol sulphate or and combinations thereof

10. A process for highly stretchable easy to wear strong synthetic polyisoprene condom made from synthetic polyisoprene latex that is pre-vulcanized by the combination of accelerators added to the latex composition subjected to increasing temperatures from 20° C. to 40° C. for up to 12 hours to pre-vulcanize the polyisoprene latex.

11. The process as recited in claim 10 having combination of accelerators including Active zinc oxide activator, Zinc diethyldithicarbamate (ZDEC) accelerator, Zinc dibenzyldithiocarbamate (ZBEC) accelerator and ZDBC accelerator.

12. The process as recited in claim 10 having at each temperature and time period a specific accelerator compound is activated extracting sulfur atoms from amorphous sulfur and transporting by surfactant sulfur pre-vulcanizing a specific location of said polyisoprene.

13. The process as recited in claim 10extracting sulfur atoms from amorphous sulfur at 20° C. by ZDBC breaking S8 bonds and producing linear chain of sulfur that is transported to polyisoprene chains by a surfactant creating pre-vulcanization in the interior of the latex particle.

14. The process as recited in claim lOactivating at temperatures from 20° C. to 40° C. other accelerators added to the polyisoprene latex attaching extracted sulfur atoms to the external surface of the polyisoprene particle creating pre-vulcanization.

15. The process as recited in claim 10 having synthetic polyisoprene latex pre-vulcanized to a required value as measured by the expansion of 130% of a cast 20 mm disk when immersed in toluene for 20 minutes per toluene swelling index test at which time the latex is ready for dipping condoms.

16. The process as recited in claim 10 having synthetic polyisoprene latex particles already pre-vulcanized, the dipped condom former in latex is vulcanized at 90° C. to 120° C.

17. The process as recited in claim 10 having low latex pre-vulcanization temperature and vulcanization temperature, production of nitrosamine below 10 ng/gm or 10 ppb or is very low minimizing or eliminating cancer risk.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0029] FIG. 1 illustrates the steps used in the current process for manufacturing condoms from synthetic polyisoprene.

DETAILED DESCRIPTION OF THE INVENTION

[0030] A condom is made from synthetic polyisoprene rubber having a combination of accelerators that cure at different progressively increasing temperatures ensuring the compete cure of the polyisoprene condom without over curing any of the accelerator cured polyisoprene due to exhaustion of sulfur vulcanizating agent at each location.

[0031] Since the vulcanization temperature is low, the formation of nitrosamines is limited. Nitrosamines are produced by the reaction of nitrite with secondary amines and is highly temperature dependent. N-Nitrosodiethylamine (NDEA) is the most potent carcinogen among the nitrosamines.

[0032] The process for producing synthetic polyisoprene condoms is as follows: First, a 15% Hostapur SAS anionic surfactant is prepared by mixing in deionized water at 50° C. Next, 10% potassium oleate solution is prepared.

[0033] The chemicals used in the process and their function is detailed below.

[0034] Sulfur: vulcanizing agent

[0035] Active zinc oxide: activator

[0036] Butylated reaction product of p creosol and dicyclopentadiene: antioxidant

[0037] Zinc diethyldithiocarbamate (ZDEC): accelerator

[0038] Zinc dibenzyldithiocarbamate (ZBEC): accelerator

[0039] Zinc dibutyldithiocarbamate (ZDBC): accelerator

[0040] Potassium hydroxide: stabilizing agent

[0041] The procedure of adding of these chemicals is detailed below:

[0042] Transfer 600 Kg of polyisoprene latex into mixing tank and agitate for 15 min

[0043] Agitate colloidal sulfur 7.8 Kg for 15 min

[0044] Add 15% Hostapur SAS surfactant solution 6.48 Kg

[0045] Add 10% Potassium oleate solution 3.78 Kg

[0046] Add 15% Eumulgin solution 7.68 Kg

[0047] Add zinc oxide activator 0.36 Kg for 15 min

[0048] Add antioxidant 3.89 Kg for 15 min

[0049] Add ZDEC 3.89 Kg for 15 min

[0050] Add ZBEC 0.79 Kg for 15 min

[0051] Add 15% Hostapur SAS solution 1.2 Kg

[0052] Add ZDBC 0.72 Kg for 15 min

[0053] Add 1.23% potassium hydroxide 28.8Kg water+0.38 Kg KOH

[0054] Agitate for 12 hours

[0055] During this period the catalytic action of ZDBC reacts with colloidal sulfur breaking down sulfur S8 rings and creating linear chains of sulfur that are carried into the synthetic polyisoprene tangled chains by the Hostapur SAS surfactant. Sulfur atoms of the sulfur chains attach to the chains of synthetic polyisoprene within the polyisoprene particle creating pre-vulcanizaion.

[0056] Since all accelerators are mixed together and added to synthetic polyisoprene, they all react based on the process temperature conditions. At low temperature, for example, 20 C, ZDBC catalytically reacts with colloidal sulfur breaking the S8 rings, forming a linear chain of sulfur, which enters the tangled synthetic polyisoprene particle with the help of the surfactant present. ZDEC also enables the attachment of sulfur from the linear sulfur chain to active sites in the polyisoprene molecule creating pre-vulcanization. As the temperature of the polyisoprene bath is raised to around 20° C.-40° C., all the accelerators react with the external surfaces of the polyisoprene particles attaching sulfur atoms to synthetic polyisoprene particle outer surface providing pre-vulcanization.

[0057] Prior to dipping of condoms the degree of pre-vulcanization is determined by the swelling index of latex in toluene. A 20 mm diameter dried disk of latex rubber film is made and is immersed in toluene for 20 minutes to expand the disk, and is measured. Un-vulcanized rubber expands to 160% of the original size. Lightly vulcanized rubber swells from 100% to 160%. Moderately vulcanized rubber swells to 80% to 100%. Fully vulcanized rubber swells to 75%. In our process, the latex is considered to be mature is ready for dipping condoms when the swelling index is 130%.

[0058] Dip tank 1 latex temperature <40° C.

[0059] Dip tank 2 latex temperature <40° C.

[0060] Latex dip temperature from 20° C. to 30° C.

[0061] Vulcanizing oven 90° C. to 120° C.

[0062] The present invention is predicated on the discovery of amorphous sulfur such as S.sub.8 rings of sulfur that is catalyzed by a zinc complex of dithiocarbamate in combination with Hostapur SAS surfactant creating pre-vulcanized synthetic polyisoprene particles in a latex composition. This latex composition enables the production of condom latex film articles by dipping coagulant free formers into the latex composition. The surfactant package inhibits synthetic polyisoprene particle agglomeration and flocculation. The latex dipped film has synthetic polyisoprene particles that become crosslinked and regions between the particles are crosslinked during the vulcanization cure forming both intra-crosslinked and inter-crosslinked bonds. The articles that result comprise a high quality and uniform latex film.

[0063] The latex-stabilizing composition is one that keeps the particles of synthetic polyisoprene separated from each other in the aqueous medium. Since the polyisoprene particles do not touch each other, they are unable to agglomerate and flock. This is important because, once the particles begin to agglomerate, the particles may never be separated due to Van der Waals forces. Preferably, the latex-stabilizing composition comprises a Hostapur SAS surfactant package. An anionic surfactant is preferred, especially one that can be stably maintained for a period of well over one month and up to two months or more. An example of such a surfactant is sodium dodecyl benzene sulphonate (SDBS). Other examples include, but are not limited to, other alkyl aryl sulphonates, alkyl sulphonates (e.g., C14 olefin sulphonate, which is sold under the trade name Calsoft AOS-40 (Pilot Chem. Co., Red Bank, NJ)), olefin sulphonates, and alcohol sulphates (e.g., sodium lauryl sulphate). SDBS or another alkyl aryl sulphonate is preferably present in an amount of about 0.1-0.35 wt %, based on the dry weight of the polyisoprene. SDBS or another alkyl aryl sulphonate can be combined with one or more other surfactants, such as potassium caprylate, polyoxyethylene cetyl/stearyl ether, and the like. For example, SDBS or another alkyl aryl sulphonate can be combined with potassium caprylate, alone or in further combination with polyoxyethylene cetyl/stearyl ether. When SDBS or another alkyl aryl sulphonate is used in combination with one or more other surfactants, preferably each surfactant is present in an amount of about 0.05-1.2 wt %, based on the dry weight of the synthetic polyisoprene, and the total amount of the surfactant package is about 0.4-1.2 wt %, based on the dry weight of the polyisoprene. When SDBS or another alkyl aryl sulphonate is used in combination with potassium caprylate and polyoxyethylene cetyl-stearyl ether, preferably the polyoxyethylene cetyl-stearyl ether is present in an amount of about 0.1-0.5 wt %, based on the dry weight of the polyisoprene.

[0064] In view of the above, the present invention provides a surfactant-stabilized, pre-vulcanized, synthetic polyisoprene latex composition having an expansion of about 130% when a cast and dried film of synthetic polyisoprene is immersed in toluene for 20 minutes. The consistency of the coagulum indicates the degree of pre-vulcanization of the latex. As the latex becomes more pre-vulcanized, the coagulum loses more of its tackiness and becomes more crumbly. An expansion of about 130% indicates that the synthetic polyisoprene is ready for the dipping of condoms. The pre-vulcanized synthetic polyisoprene may be stored indefinitely at 20° C. to 30° C.

[0065] The pre-vulcanization composition includes potassium caprylate and SDBS or another alkyl aryl sulphonate surfactant with zinc dithiocarbamate and amorphous sulfur that is extracted by ZDBC. The latex emulsion with surfactants wets the synthetic polyisoprene particles, the catalytic action of zinc dithiocarbamate breaks the ring of amorphous S.sub.8 molecule forming a linear chain of sulfur that pre-vulcanizes particles of synthetic polyisoprene. The post-vulcanization composition has sulfur and other accelerators that cause inter-particle cross-linking during the vulcanization cure. Such cross-linking results in a more homogeneous latex film having greater strength and elongation properties and crosslink density.

[0066] Preferably, the pre-vulcanizing composition comprises (i) a cross-linking package comprising zinc diethyldithiacarbamate or zinc dibutyldithiocarbamate accelerator and sulfur and (ii) a wetting agent. During pre-vulcanization, sulfur with its ring structure is broken by the catalytic action of the zinc dithiocarbamate accelerator that penetrates the polyisoprene particles and initially interacts with the isoprene double bonds therein. The catalytic reactivity of zinc dithiocarbamate is detailed in the publication entitled “The Mechanism of Zinc(II)-Dithiocarbamate-Accelerated Vulcanization Uncovered; Theoretical and Experimental Evidence” by Nieuwenhuizen, et al. is published in J. Am. Chem. Soc., 121 (1), 163 -168, 1999. A second publication entitled “Zinc accelerator complexes. Versatile homogeneous catalysts in sulfur vulcanization” by Nieuwenhuizen published in Applied Catalysis A: General 207 (2001) 55-68. These two publications discuss the mechanism of catalytic action of zinc dithiocarbamates specifically zinc dimethyldithiocarbamate with sulfur. The sulfur gets captured within four atoms of zinc in the accelerator molecule and moves in and out as a catalytic activity. The book published by Garry R. Hamed, professor at University of Akron, the chapter 2 of which is available at web address files.hanser.de/hanser/docs/20040401_244515439-6683_3-446-21403-8.pdf clearly indicates in Chapter 2.3.1.1. that for sulfur to be soluble it must have S8 rings. Amorphous or polymeric sulfur are not soluble. Diffusion of sulfur into synthetic polyisoprene particle requires sulfur to be soluble. The same chapter indicates that with ZDBC, you need only small amount of sulfur since ZDBC is an ultrafast accelerator. The web article at http://www.chemistrymag.org/cji/2007/097032pe.htm entitled ‘Effect of adding pyridine ligand on the structure and properties of complex Zn(S.sub.2CNBz.sub.2).sub.2’ by Zhong et al. indicates that zinc dibenzyldithiocarbamate and zinc dipyridinedithiocarbamate also have similar functionality of catalytic activity with sulfur. The wetting agent facilitates wetting of the polyisoprene particles and brings soluble sulfur with ring structure broken by zinc dithiocarbomate catalytic action into contact with the surface of the polyisoprene particles and permeation of sulfur occurs during processing time provided. The pre-vulcanized structure of the aqueous latex emulsion is stable for a prolonged period of time, e.g., as long as two months at the aqueous latex emulsion holding temperature without the problems of flocking and latex emulsion instability unlike the “pre-curing” procedure of U.S. Pat. No. 6,828,387 to Wang, which provides latex emulsion stable only for a maximum period of 8 days and is thus unsuited for manufacturing condoms.

[0067] Sulfur is preferably present in the synthetic polyisoprene latex emulsion in an amount of about 0.8-1.8 wt %, based on the dry weight of polyisoprene. If zinc oxide is used, preferably it is present in an amount of about 0-0.5 wt %, based on the dry weight of polyisoprene, whereas, zinc diethyldithiocarbamate or zinc dibutyldithiocarbamate is used it is preferably present in an amount of about 0.3-1.0 wt % or more preferably about 0.3-0.45 wt %, based on the dry weight of polyisoprene.

[0068] Examples of suitable wetting agents include, but are not limited to, salts (e.g., sodium salt or potassium salt) of fatty acids, which are anionic, e.g., sodium stearate, sodium oleate, and potassium caprylate. Potassium caprylate is advantageously used with a salt of a short-chain fatty acid, SDB S and polyoxyethylene cetyl/stearyl ether. Potassium caprylate is used in an amount of 0.1-0.5 wt %, based on the dry weight of polyisoprene.

[0069] The penetration of the components of the pre-vulcanizing composition into the polyisoprene particles is a strong function of the polyisoprene particle size and size distribution. Typically, smaller particles have a larger surface area, and the components of the pre-vulcanizing composition penetrate these small particles more rapidly. However, these larger surface areas result in more inter-particle regions over intra-particle regions since those smaller particles tends to pre-vulcanize faster than larger particles which are not only larger particles but they are aggregates of smaller particles and are more difficult to pre-vulcanize. In contrast, larger particles have a smaller surface area, and the components of the pre-vulcanizing composition penetrate these large particles more slowly. The smaller surface areas result in less inter-particle regions. Therefore, there is a delicate balance in selecting the size and size range distribution of the polyisoprene particles to produce optimal strength properties that balance pre-vulcanization intra-particle cross-linking with post-vulcanization inter-particle cross-linking. As indicated above, particles in the range of about 0.2-2 micrometers provide optimal results. The penetration of the components of the pre-vulcanizing composition into the polyisoprene particles is also a function of the diffusion process, itself, which is a linear function of time and an exponential function of temperature, reflecting a thermally activated process. Therefore, increasing the temperature by a few degrees during the pre-vulcanization step increases significantly the pre-vulcanization rate. For example, pre-vulcanization at room temperature requires about 12 hours of maturation after the mixing process. However faster pre-curing is typically avoided so as to prevent pre-vulcanization taking place only on periphery of large aggregates as that would result in poor ultimate strength properties of the film: this is the case hardening reaction and the use of potassium caprylate has demonstrated that it would facilitate transporting curative agents into the particles thus accelerating the rate of pre-vulcanization.

[0070] The method comprises adding a latex-stabilizing composition, such as one comprising a surfactant package of at least one surfactant, such as 15% Hostapur anionic surfactant. The surfactant is present in an amount of about 0.1-0.5 wt %, based on the dry weight of the synthetic polyisoprene. Upon addition of the latex-stabilizing composition, the emulsion is stirred, e.g., for about 12 hours, to keep the synthetic polyisoprene particles from touching each other.

[0071] The method further comprises the steps of adding post-vulcanization composition to the synthetic polyisoprene latex emulsion with accelerators selected from the group consisting of reactive zinc oxide, zinc based accelerators: ZDEC, ZBEC and ZDBC. If reactive zinc oxide is present, preferably it is present in an amount of about 0 to 0.5 wt %, based on the dry weight of synthetic polyisoprene. The composition thus produced is stable for up to about 60 days at 25° C. and can be used in a production line.

[0072] This method may also produce synthetic polyisoprene probe covers. Since the probe cover is devoid of any nitrosamine the cancer causing agents are not transferred to the user thereby minimizing cancer risk.

[0073] Table 1 below shows an example of a composition that exhibits pre-vulcanization behavior. A typical mixing sequence of the aqueous synthetic latex emulsion is illustrated. The table lists the steps and the time period involved.

TABLE-US-00001 TABLE 1 Formulation Kg Synthetic Latex agitate 15 min 600 Colloidal Sulfur agitate 15 min 7.8 15% Hostapur SAS 6.48 10% Potassium Oleate 3.78 15% Eumulgin 7.68 Disperacc HRZ50 agitate 15 min 0.36 Dispernox L50 agitate 15 min 3.89 Disperacc ZDEC agitate 15 min 3.89 Disperacc ZBEC agitate 15 min 0.79 15% Hostapur SAS 1.20 Disperacc ZDBC agitate 15 min 0.72 1.23% Potassium Hydroxide 0.38 KOH 28.8 H.sub.2O Agitate 12 hr

[0074] Thus, the present invention further provides a method of forming a synthetic polyisoprene latex condom article. The former can be any suitable former as is known in the art. The method comprises dipping a condom former in the above-described pre-vulcanized synthetic polyisoprene aqueous latex emulsion composition with a solid content of 40 to 60% with a viscosity of 20 to 30 seconds, to form a thin layer of latex film with a thickness of 25 to 35 microns with individual particles of pre-vulcanized synthetic polyisoprene touching each other on the surface of the former. The swelling index in toluene is 100 to 130% after 20 minutes exposure of a cast disk of synthetic polyisoprene.

[0075] After the first layer of latex film is not runny with a typical thickness of 25 to 35 microns, the condom former is dipped a second time into a prevulcanized synthetic polyisoprene emulsion to form into a combined thicker latex layer of about 45 to 80 microns. This enhanced thickness of the latex layer prevents tearing as the condom donned.

[0076] The tensile properties of condoms produced are shown below in Table II.

TABLE-US-00002 TABLE II Extension at break Breaking Load Elongation Tensile Strength (mm) (N) (%) (Mpa) Sample No. Naked Foil Naked Foil Naked Foil Naked Foil 1 499.3 468.5 65.0 61.0 972.69 913.46 21.96 20.61 2 496.7 472.0 68.0 67.0 967.69 920.19 23.29 23.59 3 498.0 455.9 72.0 59.0 950.00 870.57 24.66 20.49 4 470.2 469.0 69.0 69.0 916.73 914.42 23.96 23.96 5 499.8 442.0 70.0 54.0 963.43 853.33 24.31 19.01 6 483.5 489.0 72.0 71.0 932.38 942.86 24.66 25.00 7 492.5 501.0 71.0 75.0 959.62 975.96 24.65 25.68 8 489.7 472.0 72.0 63.0 934.34 900.94 25.00 21.88 9 469.5 472.0 69.0 67.0 905.71 910.48 23.63 24.28 10 500.0 495.1 67.0 64.0 963.81 954.48 22.95 22.86 11 505.0 469.0 79.0 61.0 973.33 904.76 27.05 21.18 12 462.5 467.0 62.0 63.5 901.92 910.58 21.23 22.36 13 453.5 469.0 57.0 65.5 875.24 904.76 19.26 23.06

[0077] The nitrosamine content was measured in several samples as shown below in Table III A & B.

TABLE-US-00003 TABLE IIIA Batch No. Batch No. Batch No. I-GNWLA06P-180238 B.5 I-GNWLA06P-180239 B.5 I-GNWLA06P-180240 B.5 Sample No. Sample No. Sample No. I04/2018 H04/2018 J04/2018 N-Nitrosamines Colour Colour Colour Descriptions Natural Natural Natural N-nitrosodimethylamine (NDMA) Not Detected.sup.a Not Detected.sup.a Not Detected.sup.a N-nitrosodiethylamine (NDEA) Not Detected.sup.a Not Detected.sup.a Not Detected.sup.a N-nitrosodipropylamine (NDPA) Not Detected.sup.a Not Detected.sup.a Not Detected.sup.a N-nitrosodibutylamine (NDBA) Not Detected.sup.a Not Detected.sup.a Not Detected.sup.a N-nitrosopiperidine (NPIP) Not Detected.sup.a Not Detected.sup.a Not Detected.sup.a N-nitrosopyrrolidine (NPYR) Not Detected.sup.a Not Detected.sup.a Not Detected.sup.a N-nitrosomorpholine (NMOR) Not Detected.sup.a Not Detected.sup.a Not Detected.sup.a N-nitrosodibenzylamine (NDBzA) Not Detected.sup.a Not Detected.sup.a Not Detected.sup.a N-nitroso-N-methyl-N-phenylamine Not Detected.sup.a Not Detected.sup.a Not Detected.sup.a (NMPhA) N-nitroso-N-ethyl-N-phenylamine Not Detected.sup.a Not Detected.sup.a Not Detected.sup.a (NEPhA) N-nitrosodiisononylamine (NDiNA) Not Detected.sup.a Not Detected.sup.a Not Detected.sup.a .sup.aThe method detection limit was 10 ng/g, where 1 ng/g = 1 ppb

TABLE-US-00004 TABLE III B The test result of N-Nitrosamine - 2016 Site: LCB Lab: TUV SUD Singapore Date of Analysis: 8 Mar. 2016-15 Mar. 2016 Testing Parameters Batch No. Batch No. G-GNWMA03-160201 B.6 G-GNWLA01-160203 B.10 Sample No. Sample No. G01/2016 H01/2016 Colour Colour Natural Natural N-Nitrosamines Leach tank 1 days, Leach tank 3 days, Descriptions 2 Dip tank, 65° C. 2 Dip tank, 55° C. N-nitrosodimethylamine (NDMA) Not Detected Not Detected N-nitrosodiethylamine (NDEA) Not Detected Not Detected N-nitrosodipropylamine (NDPA) Not Detected Not Detected N-nitrosodibutylamine (NDBA) Not Detected Not Detected N-nitrosopiperidine (NPIP) Not Detected Not Detected N-nitrosopyrrolidine (NPYR) Not Detected Not Detected N-nitrosomorpholine (NMOR) Not Detected Not Detected N-nitrosodibenzylamine (NDBzA) Not Detected Not Detected N-nitroso-N-methyl-N-phenylamine (NMPhA) Not Detected Not Detected N-nitroso-N-ethyl-N-phenylamine (NEPhA) Not Detected Not Detected N-nitrosodiisononylamine (NDiNA) Not Detected Not Detected a) The method detection limit was 10 ng/g, where 1 ng/g = 1 ppb Remark: Production Period February 2016

[0078] FIG. 1 shows the steps involved in creating synthetic polyisoprene latex that is free from nitrosamines. It illustrates the process flow chart for the manufacture of dipped and cured synthetic polyisoprene condom. The process begins stripping previously made condom formers. The former is dipped in a nitric acid bath, followed by a dip in two acid baths. The former is then dried in an oven. It is then dipped in pre-vulcanized synthetic latex #1 which has about 50 to 55% total solid content at 20 to 30° C. The viscosity of the latex is about 18 to 22 sec using Ford cup# 4. The thickness of latex layer formed is about 25-35 microns. The latex layer coated former is dried to ensure the latex is no longer runny. Next, the latex coated condom former is dipped in a second pre-vulcanized synthetic latex solution, which has a solid content of 50 to 55% but with a viscosity of 25-30 sec ford cup# 6. The second latex dip produces a thicker layer of synthetic latex layer typically making the total thickness 45 to 80 microns. The thicker layer prevents tearing of condoms.

[0079] All references, including publications, patent applications, and patents, cited herein are hereby incorporated by reference to the same extent as if each reference were individually and specifically indicated to be incorporated by reference and were set forth in its entirety herein.

[0080] The use of the terms “a,” “an,” “the,” and similar referents in the context of describing the invention (especially in the context of the following claims) are to be construed to cover both the singular and the plural, unless otherwise indicated herein or clearly contradicted by context. Recitation of ranges of values herein are merely intended to serve as a shorthand method of referring individually to each separate value falling within the range, unless otherwise indicated herein, and each separate value is incorporated into the specification as if it were individually recited herein. All methods described herein can be performed in any suitable order unless otherwise indicated herein or otherwise clearly contradicted by context. The use of any and all examples, or exemplary language (e.g., “such as”) provided herein, is intended merely to illuminate better the invention and does not pose a limitation on the scope of the invention, unless otherwise claimed. No language in the specification should be construed as indicating any non-claimed element as essential to the practice of the invention.