Laminates with improved tensile properties

Abstract

The present invention relates to a method for preparing an elastomeric laminate article, comprising the steps of: preparing a first aqueous coating composition comprising a first polymer and discrete silicon dioxide nanoparticles, the first polymer being a polyurethane; preparing a second aqueous coating composition comprising a second polymer; coating a substrate with the first aqueous coating composition to form a first film on the substrate; coating the first film with the second aqueous coating composition to form a second film on the first film; and removing the substrate. In another aspect, the present invention relates to an elastomeric laminate article comprising a plurality of polymeric films and one or more interfaces, wherein each pair of adjacent films defines one of the interfaces, at least one of the plurality of polymeric films comprises polyurethane, the laminate comprises silicon dioxide nanoparticles, and at least 60% by weight of the silicon dioxide nanoparticles are present at one or more of the interfaces at least partially defined by the film comprising polyurethane. In either case, the laminate article may be a condom, and the present invention further relates to a condom obtainable or obtainable by the method of the present invention.

Description

[Technical field]

[0001] The present invention relates to a laminate having improved tensile properties and a method for preparing the same. The laminate is an elastomeric article, which may be, for example, a film that is used in contact with the human body (such as in contact with the skin), and may be used, for example, as a barrier during sexual activity or during medical procedures. In one embodiment, the present invention relates to a condom that has improved tensile strength compared to the prior art, while having the same softness and elasticity as the prior art. [Background technology]

[0002] The ability of a condom to maintain its integrity throughout sexual intercourse is essential to its role as a contraceptive and to prevent the spread of sexually transmitted diseases. A condom must also be highly deformable while at the same time being thin and flexible enough to be sensitive to touch and sensation. Several polymeric materials have been found to be suitable for this purpose. Natural rubber latex ("NRL") has been used as a condom material for many years, but synthetic polyisoprene ("PI") condoms have been developed as an alternative for people with latex allergies. Polyurethane ("PU") condoms are also known. PU condoms can be manufactured with thinner walls than NRL and PI condoms due to the inherent strength of the PU material, but are typically less stretchy or soft. Thinner condoms are attractive to some consumers, in part because they may reduce the loss of sensation and pleasure compared to thicker walled condoms. Polyurethane condoms also exhibit improved thermal conductivity compared to NRL, which may result in consumers experiencing heightened sensation and more pleasure. Some attempts have been made to improve the mechanical properties of the elastomeric films from which condoms are made. However, it is often difficult to improve one mechanical property without adversely affecting others. Reinforcing materials that have been used in elastomers to date include silica, carbon black, carbon nanotubes, and graphene. However, the incorporation of these substances, due to their stiffness, also increases the hardness and stiffness of the material (reflected in an increase in the elastic modulus) and tends to reduce the elongation at break. This is disadvantageous for condom applications, so highly elastic materials are typically avoided, as they may reduce the feel or sensitivity.

[0003] Similar principles apply to other elastomeric laminate articles such as gloves, finger cots, dental dams, balloon catheters, etc. Such articles may be manufactured, for example, by dipping. US Patent Application Publication No. 2017 / 0333602 discloses the use of nanocellulose as an additive for elastomeric materials, which may include polyurethane, with the objective of providing enhanced tensile strength and toughness while avoiding significant increases in modulus or stiffness. There remains a need for additional methods for improving the tensile properties of laminates, such as condoms, and in particular, for improving the tensile strength of laminates without significantly affecting the laminate's modulus. Summary of the Invention

[0004] According to a first aspect, the present invention provides a method for preparing an elastomeric laminate article, comprising the steps of: (i) providing a first aqueous coating composition comprising a first polymer and discrete silicon dioxide nanoparticles, the first polymer being a polyurethane; (ii) providing a second aqueous coating composition comprising a second polymer; (iii) coating the substrate with a first aqueous coating composition to form a first film on the substrate; (iv) coating the first film with a second aqueous coating composition to form a second film on the first film; and (v) Removing the substrate The present invention provides a method comprising: In one embodiment, the article is a condom. In one embodiment, the first aqueous coating composition is coated onto the substrate by immersing the substrate in the composition. If the substrate is a molded former (such as a condom former), the method may include removing the laminate from the substrate to provide the formed article (such as a condom). In another embodiment, the laminate film may first be removed from the substrate and then formed into the article, for example, by thermoforming.

[0005] By coating a substrate with multiple films in sequence, the thickness of the elastomeric body can be built up to an appropriate level to obtain a consistent thickness along the length of the condom or other article. However, the inventors believe that the interface between the films becomes a weak point of the structure. They have found that by incorporating discrete silicon dioxide nanoparticles into at least a first film-forming composition comprising polyurethane, a condom is obtained that has improved tensile strength compared to an equivalent condom that does not contain discrete silicon dioxide nanoparticles, without a significant increase in elastic modulus. In particular, the inventors have found that the discrete silicon dioxide nanoparticles (unlike other forms of silica) can migrate to the interface between the first coated layer and the surrounding air, with only a limited amount remaining dispersed within the bulk of the polymer matrix. This means that when a second film is formed on the first film, the silicon dioxide nanoparticles are present at the interface between the two films. Without wishing to be bound by theory, it is believed that the silicon dioxide nanoparticles present at the interface can provide reinforcement to an interface that would otherwise be an inherent structural weak point, without significantly interfering with the bulk properties of the elastomer. Since there is no significant buildup of silica in the bulk, the modulus, or the ability of the elastomer to withstand change when strained, is not compromised. This results in improved condom tensile strength without a significant increase in modulus. It is believed that the same principles apply to other laminate articles, especially thin ones.

[0006] According to a second aspect, the present invention provides an elastomeric laminate article (preferably a condom) obtainable or obtainable by the method according to the first aspect. According to a third aspect, the present invention provides an elastomeric laminate article comprising a plurality of polymeric films and one or more interface surfaces, each pair of adjacent films defining one of the interface surfaces; At least one of the plurality of polymer films comprises polyurethane; the elastomeric laminate article comprises silicon dioxide nanoparticles; and At least 60% by weight of the silicon dioxide nanoparticles are present at one or more of the interfaces defined at least in part by the film comprising polyurethane; Provide goods.

[0007] According to a fourth aspect, the present invention provides a condom comprising a laminate, the laminate comprising a plurality of elastomeric films and one or more interface surfaces, each pair of adjacent elastomeric films defining one of the interface surfaces; At least one of the plurality of elastomeric films comprises polyurethane; the laminate comprises silicon dioxide nanoparticles, and At least 60% by weight of the silicon dioxide nanoparticles are present at one or more of the interfaces defined at least in part by the film comprising polyurethane; Provide condoms. According to a fifth aspect, the present invention provides a sealed package comprising a condom according to the second or fourth aspect. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] The present invention is further described below. In the following passages, different aspects / embodiments of the present invention are defined in more detail. Each aspect / embodiment thus defined may be combined with other aspects / embodiments, unless expressly indicated to the contrary. In particular, features indicated as being preferred or advantageous may be combined with other features indicated as being preferred or advantageous. The present invention provides a method for preparing an elastomeric laminate article. In one embodiment, the laminate article is a dipped good. The article may be for wearing in or on the body. In one embodiment, the article is a film for use in contact with the human body (such as in contact with the skin). The article may be for use in sexual activity or during a medical procedure. Examples of laminate articles that may be produced according to the present invention include condoms, dental dams, finger cots, gloves, and balloon catheters. In one embodiment, the laminate article is less than 1 mm thick, preferably less than 500 μm thick, and most preferably less than 100 μm thick. In one embodiment, the article is a condom. The condom is preferably a male condom, intended to cover substantially the entire penis. Alternatively, in some embodiments, the condom is a female condom.

[0009] The first step of the method involves preparing a first aqueous coating composition comprising a first polymer and discrete silicon dioxide nanoparticles. The first polymer is a polyurethane. The nature of the polyurethane is not particularly limited, provided that it is capable of forming a film having one or more mechanical properties (e.g., strength or flexibility) required for the article to be formed. For example, polyurethanes suitable for use as materials for condoms are known in the art. The polyurethane may be a polyether-based polyurethane, i.e. a polyurethane obtained from the polymerization of a diisocyanate and a polyether. Alternatively, the polyurethane may be a polyester-based polyurethane, i.e. a polyurethane obtained from the polymerization of a diisocyanate and a polyester. The polyurethane may be an aliphatic polyurethane, i.e. a polyurethane that does not contain aromatic structures. Alternatively, the polyurethane may be an aromatic polyurethane. The first polymer may be provided in a mixture with one or more further polyurethanes. It may be an elastomeric or a thermoplastic elastomer, but is preferably elastomeric.

[0010] Preferably, the first polymer is hydrophobic. Preferably, the first polymer has a logarithmic partition coefficient (logP) greater than 1. The term "partition coefficient" is known in the art and refers to the octanol-water partition coefficient (P), i.e., the partition ratio of a substance in a mixture of 1-octanol and water at equilibrium. The logarithmic partition coefficient is the logarithm of the partition coefficient to the base 10. A logP greater than 1 indicates hydrophobicity. Hydrophobic polymers may be advantageous in the present invention because they have a lower tendency to associate with the discrete silicon dioxide nanoparticles than hydrophilic polymers and therefore do not impede the movement of the discrete silicon dioxide nanoparticles to the air interface during the coating process. As explained above, it is believed that the movement of the discrete silicon dioxide nanoparticles to the interface ultimately allows the present invention to improve tensile strength without a significant increase in modulus. As mentioned above, the first aqueous coating composition comprises discrete silicon dioxide ("silica") nanoparticles. By "nanoparticles" is meant particles with a diameter of 1 to 1000 nm. By "discrete" is meant that the particles are present in the first aqueous coating composition individually or in a loosely associated form and have not fused to form aggregates or agglomerates. In embodiments where the particles are loosely associated in the aqueous coating composition, the particles are still considered to be discrete (as opposed to fused to form aggregates or associations) since they may be separated again by stirring or dispersion. It is understood that the discrete silicon dioxide nanoparticles are amorphous, i.e. non-crystalline. Preferably, the discrete silicon dioxide nanoparticles are non-porous. Preferably, the discrete silicon dioxide nanoparticles are spherical or substantially spherical.

[0011] The discrete silicon dioxide particles used in the first aqueous coating composition are distinguished from other forms of silica. The preparation of fumed silica involves hydrolysis of silicon tetrachloride vapor in a flame of hydrogen and oxygen. During the combustion process, roughly spherical molten particles are formed. These molten spheres of fumed silica, typically referred to as primary particles, fuse together by collision at their contact points to form branched, three-dimensional chain-like aggregates. The forces required to break the aggregates are substantial and, due to fusion, are often considered irreversible. During cooling and recovery, the aggregates may undergo further collisions and mechanical entanglement to form agglomerates. Compared to agglomerates of fused primary particles, the agglomerates are considered to be loosely held together by van der Waals forces and can be inverted, i.e., deagglomerated, to form agglomerates by proper dispersion in a suitable medium. However, because the primary particles are fused, these aggregates cannot be inverted to form primary particles. As a result of the aggregation and agglomeration, fumed silica cannot be considered to be composed of discrete nanoparticles. Another amorphous form of silica is precipitated silica, which is formed from a solution containing silicate salts. Like fumed silica, the primary particles of precipitated silica cannot be considered to be composed of discrete nanoparticles, since they form aggregates and agglomerates (of fused primary particles) during the manufacturing process. Precipitated silica is a porous form of amorphous silica.

[0012] Preferably, the discrete silicon nanoparticles used in the first aqueous coating composition contain surface silanol (Si-OH) groups. That is, the silanol groups are preferably present on the surface of the nanoparticles. Due to the hydrophilic silanol groups on the surface and the hydrophobic Si-O-Si moieties in the silicon dioxide nanoparticle core, such silicon dioxide nanoparticles are amphiphilic. As a result, they can adsorb to the surface of the polymer-water droplets (air-water interface), and they help the polymer to migrate to the interface between the first film and the air during the coating process, rather than remaining within the bulk of the polymer matrix. Preferably, the discrete silicon dioxide nanoparticles have an average particle size of 100 nm or less, preferably 90 nm or less, 80 nm or less, 70 nm or less, 60 nm or less, 50 nm or less, 40 nm or less, 30 nm or less, 20 nm or less, or 10 nm or less. Preferably, they have an average particle size of 1-100 nm, more preferably 2-50 nm, even more preferably 4-20 nm, and most preferably 5-10 nm. The average particle size can be measured, for example, by dynamic light scattering (DLS). Preferably, the average particle size is measured by the volume weighted average particle size (D 4,3 ) In the present invention, small particle sizes are believed to be advantageous, in part, due to their increased ability to migrate to the coating layer / air interface during the coating process.

[0013] Preferably, the discrete silicon dioxide nanoparticles are at least 200 mm in size. 2 / g, more preferably at least 250m 2 / g, and most preferably at least 300m 2 / g. It is believed that silicon dioxide nanoparticles with a larger surface area may provide a greater improvement in tensile strength. Preferably, the first aqueous coating composition comprises the first polymer in an amount of at least 10%, more preferably at least 15%, at least 20% or at least 25% by weight, based on the weight of the first aqueous coating composition. Preferably, the first polymer is present in an amount of up to 60%, up to 50%, or up to 40% by weight, based on the weight of the first aqueous coating composition. In one embodiment, the first aqueous coating composition comprises the first polymer in an amount of 10-50%, more preferably 20-40% by weight, based on the weight of the first aqueous coating composition. Preferably, the first aqueous coating composition comprises 0.1 to 3 wt. %, more preferably 0.2 to 4 wt. %, even more preferably 0.3 to 2 wt. %, and even more preferably 0.5 to 1 wt. % of discrete silicon dioxide nanoparticles, based on the weight of the first aqueous coating composition.

[0014] Preferably, the first aqueous coating composition comprises the first polymer and the discrete silicon dioxide nanoparticles in a weight ratio of from 5:1 to 200:1, more preferably from 10:1 to 200:1, even more preferably from 20:1 to 150:1, and most preferably from 40:1 to 80:1. The first step of the method of the present invention preferably comprises combining a source of a first polymer with a source of discrete silicon dioxide nanoparticles to form a first aqueous coating composition. The source of the first polymer may be a dispersion of the first polymer in a liquid, preferably an aqueous dispersion. Thus, the source of the first polymer is preferably an aqueous polyurethane dispersion ("PUD"). PUDs suitable for forming condoms and other articles are commercially available, such as Alberdingk® U228 from Alberdingk Boley. Preferably, the source of discrete silicon dioxide nanoparticles can be a dispersion of discrete silicon dioxide nanoparticles in a liquid. Such dispersions are known in the art as "colloidal silica". It is believed that the use of colloidal silica, rather than a solid form of silica, facilitates the dispersion of the nanoparticles and their migration to the interface. Preferably, the dispersion is an aqueous dispersion. Preferably, the aqueous dispersion has a pH of 7-11, more preferably 8-10. A suitable source of silicon dioxide nanoparticles for use in the present invention is Ludox® SM colloidal silica, which is an aqueous dispersion.

[0015] The first aqueous coating composition may further include other ingredients typically included in polyurethane-based condom-forming materials. For example, the first aqueous coating composition may further include a crosslinker, such as a carbodiimide crosslinker, preferably in an amount of 0.2 to 5% by weight, more preferably 0.5 to 2% by weight, based on the weight of the first aqueous coating composition. Alternatively or additionally, the first aqueous coating composition may further comprise a surfactant, preferably in an amount of 0.05-1 wt %, more preferably 0.1-0.5 wt %, based on the weight of the first aqueous coating composition. It is believed that silicon dioxide nanoparticles may cause an increase in the surface tension of the first aqueous coating composition, making it more difficult to form a uniform layer on the substrate. The inclusion of a surfactant serves to reduce the surface tension of the first aqueous coating composition, making it easier to form a uniform layer on the substrate. Surfactants suitable for reducing the surface tension of the aqueous coating composition are known in the art and include, for example, alkoxylated surfactants, such as polyether-modified siloxane surfactants.

[0016] The first aqueous coating composition preferably contains 40 to 90 mass %, more preferably 50 to 80 mass %, and even more preferably 60 to 75 mass % of water, based on the mass of the first aqueous coating composition. The second step of the method of the present invention involves preparing a second aqueous coating composition comprising a second polymer. The nature of the second polymer is not particularly limited, provided that it is capable of forming a film having one or more mechanical properties (e.g., strength or flexibility) required for the desired article, such as a condom. Several suitable polymers are known in the art, such as polyurethane, polyisoprene, polyethylene, copolymers of acrylonitrile and butadiene ("nitrile rubber"). Preferably, the second polymer is selected from polyisoprene, polyurethane, or mixtures thereof. The polyisoprene can be synthetic cis-1,4-polyisoprene. Alternatively, the polyisoprene can be provided in the form of natural rubber latex ("NRL"). Natural rubber latex typically contains small amounts of impurities, such as proteins, lipids, carbohydrates, inorganic salts, along with cis-1,4-polyisoprene. Synthetic polyisoprene is suitable for users who are sensitive to latex, for example, because it does not contain allergenic proteins found in natural rubber latex.

[0017] Most preferably, the second polymer is a polyurethane. In this embodiment, each of the optional or preferred features discussed above in relation to the first polymer is equally applicable to the second polymer. The second polymer and the first polymer may be the same or different. For example, the first polymer may be a polyurethane and the second polymer may be a polyisoprene, or vice versa. As another example, the first polymer and the second polymer may be two different polyurethanes (e.g., having different molecular weights or monomer unit compositions). However, preferably, the first polymer and the second polymer are the same (i.e., the same polyurethane). In some embodiments, the second aqueous coating composition can further comprise discrete silicon dioxide nanoparticles. As described below, such embodiments are particularly preferred when further comprising forming a third film on the second film.

[0018] In embodiments in which the second aqueous coating composition further comprises discrete silicon dioxide nanoparticles, the second step of the method preferably comprises combining a source of a second polymer with a source of discrete silicon dioxide nanoparticles to form a second aqueous coating composition. The source of the second polymer may be a dispersion of the second polymer in a liquid, preferably an aqueous dispersion. If the second polymer is a polyurethane, the source of the second polymer is preferably an aqueous polyurethane dispersion ("PUD"), as described above. If the second polymer is a polyisoprene, the source of the second polymer is preferably an aqueous dispersion of synthetic cis-1,4-polyisoprene or an aqueous polyisoprene dispersion, such as natural rubber latex. Suitable blends of natural rubber latex and synthetic polyisoprene are known in the art. Each of the optional or preferred features described above in relation to the "source of discrete silicon dioxide nanoparticles" in relation to the first aqueous coating composition also apply to the second aqueous coating composition. Each of the optional or preferred features described above in relation to the first coating composition and its components can be applied to the second aqueous coating composition as well.Preferably, the first aqueous coating composition and the second aqueous coating composition are the same.For example, the first aqueous coating composition and the second aqueous coating composition can constitute a single composition used in the coating process described below.

[0019] The third step of the method involves coating a substrate with a first aqueous coating composition to form a first film on the substrate. The substrate is subsequently removed and does not become part of the finished product. In some embodiments, the substrate is a former. The term "former" is known in the art and, in the case of a condom former, refers to a condom-shaped mold to which the polymeric coating composition is applied to form a condom. The former may be made of, for example, glass, plastic, or ceramic. In other embodiments, the substrate is a cast, plate, or sheet. In one embodiment, the substrate is a glass, plastic, ceramic plate or sheet. In these embodiments, the first film is typically flat rather than taking the shape of the article to be formed. The term "film" refers to a thin layer of polymeric material, the thickness of which is typically on the order of a few microns to tens of microns, such as 5-30 μm. The third step preferably includes applying a layer of the first aqueous coating composition to the substrate and drying the layer of the first aqueous coating composition to form a first film. Applying the layer of the first aqueous coating composition to the substrate may include dipping the substrate into the first aqueous coating composition or spraying, brushing, casting or rolling the first aqueous coating composition onto the substrate. The layer of the first aqueous coating composition may be applied directly to the substrate or, in some embodiments, a coagulant is applied to the substrate prior to application of the first aqueous coating composition. In some embodiments, the substrate is stationary when the layer of the first aqueous coating composition is applied. In other embodiments, the substrate is moving when the layer is applied. In embodiments where the substrate is dipped into the first aqueous coating composition, the thickness of the layer can be controlled by varying the dipping and / or withdrawal speed. The drying step can be performed by open air or evaporation in an oven or evaporator. In some embodiments, the substrate is heated to facilitate drying.

[0020] As explained above, a significant proportion of the discrete silicon dioxide nanoparticles can migrate to the air-coating interface during the coating process. These silicon dioxide nanoparticles are fixed at the air interface when the first film is formed. At this stage, at least some of the silicon dioxide nanoparticles present at the interface can be loosely associated or clustered with each other. Other silicon dioxide nanoparticles present at the interface or in the bulk of the polymer matrix can remain in a completely individualized form. It will be understood that the silicon dioxide nanoparticles, even if some of them are loosely associated, do not fuse together to form aggregates or agglomerates as described above for fumed silica. Preferably, the temperature and duration of the drying step are sufficient for the first film to have a moisture content of less than 10% by weight, more preferably less than 5% by weight. The temperature and duration of the drying step may vary depending on the ingredients of the first aqueous coating composition (including the nature of the first polymer) and the thickness of the layer. The layer is preferably dried at a temperature of 40-100°C, more preferably 50-70°C, and / or for 1-10 minutes, more preferably 3-7 minutes.

[0021] In some embodiments, the layer of the first aqueous coating composition undergoes a chemical change during the drying process. For example, in embodiments in which the first aqueous coating composition includes a crosslinker, crosslinks between polymer chains of the first polymer may form during the drying process. In some embodiments, the first film has a thickness of 5 to 30 μm. The preferred thickness of the first film varies depending on the number of coating steps and the desired thickness of the final article, which also depends to some extent on the polymeric material from which the final article is formed. For example, polyurethane-based films, given their inherent strength greater than polyisoprene-based films, may have suitable strength for use as a condom material at a lower thickness. The first film comprising polyurethane preferably has a thickness of 5 to 15 μm, more preferably 6 to 10 μm.

[0022] The fourth step of the method of the present invention comprises coating the first film with a second aqueous coating composition to form a second film on the first film. It is understood that the second aqueous coating composition is applied directly to the first film so that the second film and the first film are in direct contact, i.e. without an intervening film or layer. The fourth step preferably comprises applying a layer of the second aqueous coating composition to the first film and drying the layer of the second aqueous coating composition to form a second film. The first film preferably remains on the substrate during the fourth step. Thus, the fourth step preferably comprises immersing the film-coated substrate in the second aqueous coating composition, or spraying, brushing, casting or rolling the first aqueous coating composition onto the film-coated substrate. Apart from the temperature and duration of the drying step, and the thickness of the resulting film, each of the optional or preferred features discussed above in relation to the third step are equally applicable to the fourth step, except that the fourth step involves coating the first film rather than the substrate itself.

[0023] The temperature and duration of the step of drying the layer of the second aqueous coating composition to form the second film depends on the nature of the second polymer. In embodiments where the second polymer is a polyurethane, the layer is preferably dried at a temperature of 40 to 100°C, more preferably 50 to 70°C, and / or for 1 to 10 minutes, more preferably 3 to 7 minutes. In embodiments where the second polymer comprises polyisoprene provided in the form of natural rubber latex, the layer is preferably dried at a temperature of 50 to 120°C, more preferably 60 to 90°C, and / or for 30 seconds to 5 minutes, more preferably 1 to 4 minutes. In embodiments where the second polymer is a synthetic cis-1,4-polyisoprene, the layer is preferably dried at a temperature of 70 to 130°C, more preferably 80 to 120°C, and / or for 30 seconds to 5 minutes, more preferably 1 to 4 minutes. The preferred thickness of the second film will vary depending on the number of coating steps and the desired thickness of the final condom, which will also depend to some extent on the polymeric material from which the final article is formed. For example, polyurethane-based films, given their inherent strength greater than polyisoprene-based films, may have suitable strength for use as a condom material at lower thicknesses. When the second polymer is polyurethane, the second film preferably has a thickness of 5-15 μm, more preferably 6-10 μm. When the second polymer is polyisoprene, the second film preferably has a thickness of 15-30 μm, more preferably 20-25 μm.

[0024] In embodiments where the first and second aqueous coating compositions are the same, the conditions (e.g., temperature and duration) of the third and fourth steps are preferably the same. Preferably, in embodiments where the first and second aqueous coating compositions are the same, the thickness of the first film is substantially the same as the thickness of the second film, or within 10% of the thickness of the second film. In some embodiments, the method further comprises the steps of preparing a third aqueous coating composition comprising a third polymer, and coating the second film with the third aqueous coating composition between the fourth and fifth steps (described below) of the method of the invention to form a third film on the second film. Each of the optional or preferred features described above in relation to the second aqueous coating composition, coating steps and film applies equally to the third aqueous coating composition, coating steps and film. Preferably, the first, second and third polymers (and preferably the first, second and third aqueous coating compositions) are the same. In other embodiments, at least two of the three polymers (or at least two of the three aqueous coating compositions) are the same and one is different. For example, the first polymer may comprise polyurethane, the second polymer may comprise polyisoprene derived from natural rubber latex, and the third polymer may comprise polyurethane. Such an embodiment would result in the formation of a laminate PU-NRL-PU article, such as a condom. In other embodiments, all three of the polymers (or all three of the aqueous coating compositions) are different.

[0025] The number of coating steps is not particularly limited, so long as the article is not too thick for its intended purpose. For example, the method may further include preparing a fourth aqueous coating composition comprising a fourth polymer, and coating a third film with the fourth aqueous coating composition to form a fourth film on the third film before the fifth step. The method may include one or more additional successive steps of preparing an aqueous coating composition and one or more additional successive coating steps. In some embodiments, the aqueous coating composition used in each step (or at least the polymer used in each coating step) is the same. In some embodiments, the method includes only three coating steps. In some embodiments, the method includes only two coating steps. In some embodiments, the method further comprises a step of heating the first film, the second film, and, if present, the third film and any subsequent films on the substrate. Such a heating step, if present, is performed before the fifth step (described below) of the method of the present invention. One purpose of such a heating step is to completely dry the film if it has not been completely dried in the previous drying step. The heating step may also induce or increase the formation of crosslinks between polymer chains present in the film. In one embodiment, the film is heated to a temperature of 60-150°C, preferably 80-140°C, and / or for a period of 5-20 minutes, preferably 8-15 minutes.

[0026] In one embodiment, the fifth step of the method of the invention comprises removing the substrate to provide an article, or removing the substrate to provide a laminate and forming an article from the laminate. In embodiments where the substrate is in the shape of a condom (e.g., a condom former), the fifth step provides a condom. In embodiments where the substrate is a cast, plate or sheet, the fifth step provides a laminate and shapes it to form a condom. In some such embodiments, forming a condom from the laminate comprises heating the laminate and contacting the heated laminate with a mandrel such that the laminate takes the shape of the mandrel. Examples of suitable means for shaping the laminate are disclosed in U.S. Pat. Nos. 4,576,156 and 5,458,936, the contents of which are incorporated by reference. In some embodiments, the fifth step comprises peeling the film structure from the substrate. In some embodiments, the film structure is leached (e.g., in an alkaline solution at a temperature of 20-40° C.) prior to removing the substrate to provide the laminate. In embodiments of the invention where the article is a condom, the condom preferably has a thickness of 10 to 60 μm. By "thickness" is meant the wall thickness (i.e. the thickness of the combination of films forming the condom as defined herein), not including the bead formed at the opening of the condom. The preferred thickness of the condom depends in part on the polymeric material from which it is formed. Preferably, the condom has a thickness of 10 to 30 μm, or 10 to 25 μm, or 10 to 20 μm. The increased tensile strength provided by the discrete silicon nanoparticles of the invention allows the thickness of the condom to be used relatively.

[0027] Preferably, the article (preferably a condom) has a tensile strength of at least 10 MPa, or at least 20 MPa, or at least 30 MPa, or at least 40 MPa. In some embodiments, the article (preferably a condom) has a tensile strength of at most 100 MPa, or at most 90 MPa, or at most 80 MPa. The term "tensile strength" refers to the maximum stress that the article can undergo before it breaks. Preferably, the article (preferably a condom) has a modulus at 300% elongation of at most 5 MPa, or at most 4 MPa, or at most 3.5 MPa. In these embodiments, the article (preferably a condom) may have a modulus at 300% elongation of at least 2 MPa, or at least 2.5 MPa, or at least 3 MPa. The term "modulus" refers to the stress at a particular elongation of the article and is related to the hardness of the material. Articles with a lower modulus feel softer and typically more pleasant to the touch.

[0028] Preferably, the article (preferably a condom) has a modulus at 500% elongation of at most 8 MPa, or at most 7 MPa, or at most 6 MPa, or at most 5.5 MPa. In these embodiments, the article (preferably a condom) may have a modulus at 500% elongation of at least 2.5 MPa, or at least 3 MPa. Preferably, the tensile strength and modulus are determined according to the procedure described in Example 2. Preferably, the tensile strength and modulus are determined according to ISO standard ISO 4074:2015. Preferably, the article (preferably a condom) has a tensile strength that is at least 10% higher, more preferably at least 20% higher, and even more preferably at least 30% higher than the tensile strength of an article (preferably a condom) prepared by the same method but without the use of discrete silicon dioxide nanoparticles. Preferably, the article (preferably a condom) has a modulus at 300% elongation that is within 10%, preferably within 5%, of the modulus of an article (preferably a condom) prepared in the same manner but without the use of discrete silicon dioxide nanoparticles.

[0029] Preferably, the article (preferably a condom) has a modulus at 500% elongation that is within 10%, preferably within 5%, of the modulus of an article (preferably a condom) prepared in the same manner but without the use of discrete silicon dioxide nanoparticles. In some embodiments, where the article is intended to be worn on the body, such as a condom, glove or finger cot (preferably a condom), the method further comprises coating one or more surfaces of the article with a finishing powder. The one or more surfaces may be an inner surface and / or an outer surface, preferably an inner surface and an outer surface. In a male condom, "inner" refers to the side facing the penis, and "outer" refers to the side facing the user's partner; in a glove or finger cot, "inner" refers to the side facing the fingers. In embodiments, where the method further comprises coating one or more surfaces of the condom with a finishing powder, this is done before rolling and before the lubricant is applied. The step of coating one or more surfaces of the article with a finishing powder may comprise applying the finishing powder to the one or more surfaces as a powder or as a liquid slurry (preferably an aqueous slurry). In the latter embodiment, the water is evaporated to form a coating of the finishing powder on one or more surfaces of the article. Finishing powders are known in the art. They are typically alkaline and based on compounds such as silica, talc, carbonates, corn starch, etc. They are used to prevent surfaces of the article from sticking together and to aid in donning. In particular, the inclusion of a finishing powder on the inside surface of a condom helps to prevent the condom from sticking to itself, while the inclusion of a finishing powder on the outside surface also helps to prevent the condom from sticking to other condoms during manufacture.

[0030] In some embodiments, the method further comprises applying a dose of lubricant to one or more surfaces of the condom to form a lubricated condom. The one or more surfaces may be the inner and / or outer surface of the condom. Preferably, the dose of lubricant is applied to at least the outer surface of the condom. Suitable lubricants for condoms are known in the art and are typically water-based or silicone oil-based. In some embodiments, the condom is rolled up before applying the lubricant. In this embodiment, the dose of lubricant may be applied to or near the tip of the rolled up condom. The lubricant may then migrate along the roll of the condom over time (including after the condom is sealed in the package as described below). In this embodiment, the condom may already be in the package at the time the dose of lubricant is applied or on a material (such as a piece of foil) that forms part of the package. In embodiments where the condom is sealed in the package, the only sealing step necessarily has to be performed after the lubricant has been applied (as described below).

[0031] Alternatively, a dose of lubricant may be applied to the condom prior to the rolling up step. The lubricant may be applied in a variety of known ways, such as by spraying, rolling over a lubricant-saturated sponge, or applying a dose of lubricant to one or more spots along the length of the condom prior to rolling. It will be appreciated that a higher viscosity of the lubricant may be tolerated if the lubricant is pre-applied to the condom in all or substantially all of the required areas, such that the lubricant does not need to migrate to the desired areas. The method may include further steps such as electrically testing the condom for holes, rolling up the condom, and / or sealing the condom in a package. Suitable sealed packages for condoms are known in the art and may for example comprise two sheets of laminate material that are sealed along the edges around the condom. The laminate material may for example comprise a layer of aluminium. Another possible sealed package is a plastic pot, the so-called "butter dish", sealed with a film lid. The condom is preferably provided in the package in a rolled up state. According to a second aspect, the present invention provides an article, preferably a condom, obtained or obtainable by a method according to the first aspect.

[0032] According to a third aspect, the present invention provides an elastomeric laminate article comprising a plurality of polymeric films and one or more interface surfaces, each pair of adjacent films defining one of the interface surfaces; At least one of the plurality of polymer films comprises polyurethane; the elastomeric laminate article comprises silicon dioxide nanoparticles; and At least 60% by weight of the silicon dioxide nanoparticles are present at one or more of the interfaces defined at least in part by the film comprising polyurethane; Provide goods. The article may be a condom. By "laminate" is meant a composite structure composed of a plurality of layers, and in the present invention, preferably a plurality of elastomeric films. The number of films is not particularly limited and depends in part on the desired thickness of the article. However, preferably, the laminate comprises only two or three films. In some embodiments, the laminate is composed of a plurality of films. It is understood that the laminate forms the wall of the article. In the case of a male condom, the condom has an inner surface (i.e., the side facing the penis during use) and an outer surface (i.e., the side facing the user's partner during use), and the surface of the laminate defines the inner and outer surfaces.

[0033] It is understood that each film comprises a polymer, preferably an elastomer (a rubbery polymer having elastic properties). The nature of the elastomer is not particularly limited, provided that it is capable of forming an elastomeric film having one or more mechanical properties (e.g., strength or flexibility) required for a condom or other article. Suitable polymers for use in the other films (preferably elastomeric films) include polyurethane, polyisoprene, polyethylene, and copolymers of acrylonitrile and butadiene ("nitrile rubber"), as described in connection with the first embodiment. The elastomeric film defining the inner surface of the condom preferably comprises polyurethane. The polymer may be the same in each film. For example, each film may comprise the same polyurethane. In some embodiments, the polymer is the same in some films but not in other films. For example, the laminate may comprise alternating films each comprising a polyurethane and a polyisoprene. Alternatively, the laminate may comprise alternating films each comprising a different polyurethane (e.g., having a different molecular weight or monomer unit composition). In other embodiments, the polymer is different in each film. Preferably, each of the plurality of layers comprises a polyurethane, preferably the same polyurethane. The polymer present in one or more of the films of the third aspect (preferably each of the films of the third aspect) is preferably crosslinked.

[0034] As mentioned above, the laminate comprises silicon dioxide nanoparticles. The silicon dioxide nanoparticles are not necessarily "discrete" as defined above in relation to the aqueous coating composition of the first embodiment. This is because at least some of the silicon dioxide nanoparticles present at one or more interfaces in the laminate may be loosely associated or clustered with each other and cannot separate again within the laminate to form completely individualized particles. Other silicon dioxide nanoparticles present at one or more interfaces or in the bulk of the film may remain in individualized form. It will be understood that the silicon dioxide nanoparticles in the laminate of the third embodiment, even if some of them are loosely associated, still do not fuse together to form aggregates or agglomerates (as described above for fumed silica). At least 60% by weight, more preferably at least 70% by weight, and most preferably at least 80% by weight of the silicon dioxide nanoparticles are present in one or more of the interfaces at least partially defined by the film containing polyurethane. In other words, at most 40% by weight, more preferably at most 30% by weight, and most preferably at most 20% by weight of the silicon dioxide nanoparticles are absent from one or more of the interfaces (i.e., they are present in the "bulk" of the film). As described above, each interface is defined by a pair of adjacent films. It will be understood that in order to define an interface, the films forming the pair must be in direct contact with each other. The term "interface" as used herein refers to a region extending from the boundary between two adjacent films to a distance of 500 nm, preferably 100 nm, or 50 nm, or 20 nm, or 10 nm on either side perpendicular to the boundary. The term "bulk" refers to the portion of the film that does not form an interface. The proportion of silicon dioxide nanoparticles present in one or more of the interfaces at least partially defined by the film containing polyurethane can be determined by scanning electron microscopy. In some embodiments, at most 95% by weight or at most 90% by weight of silicon dioxide nanoparticles are present at one or more of the interfaces at least partially defined by the film comprising polyurethane.In other words, in some embodiments, at least 5% by weight or at least 10% by weight of silicon dioxide nanoparticles are not present at one or more of the interfaces at least partially defined by the film comprising polyurethane.The silicon dioxide nanoparticles present in the bulk of the film may be dispersed in the polymer matrix and / or present in one or more defects in the film.

[0035] As explained above, the inventors have found that by concentrating silicon dioxide nanoparticles at the interface between a pair of adjacent films rather than in the bulk, it is possible to reinforce the structural weaknesses associated with the interface without significantly interfering with the properties of the bulk polymer. This can be done when at least one of the films comprises polyurethane. As a result, the tensile strength of the article can be improved without a significant increase in the modulus of elasticity. Preferably, the silicon nanoparticles contain surface silanol (Si-OH) groups. That is, the silanol groups are preferably present on the surface of the nanoparticles. Due to the hydrophilic silanol groups on the surface and the hydrophobic Si-O-Si moieties in the silicon dioxide nanoparticle core, such silicon dioxide nanoparticles are amphiphilic. This is one way to increase the concentration of silicon dioxide nanoparticles at one or more interfaces relative to the bulk. This is because during the preparation of the laminate, the amphiphilic silicon dioxide nanoparticles can adsorb to the surface of the polymer-water droplets (air-water interface) and help them migrate to one or more interfaces rather than remaining within the bulk of the polymer matrix.

[0036] Preferably, the silicon dioxide nanoparticles have a primary particle size of 1-100 nm, more preferably 2-50 nm, even more preferably 4-20 nm, and most preferably 5-10 nm. By "primary particle size" we mean the diameter of an individual silicon dioxide nanoparticle, not the size of an association or cluster of nanoparticles. Preferably, the silicon dioxide nanoparticles are at least 200 μm. 2 / g, more preferably at least 250m 2 / g, and most preferably at least 300m 2 / g BET surface area. Preferably, the laminate comprises at least 2%, at least 3%, at least 4%, at least 5% or at least 6% by weight of silicon dioxide nanoparticles relative to the weight of the laminate. Preferably, the laminate comprises at most 10% by weight of silicon dioxide nanoparticles relative to the weight of the laminate.

[0037] Preferably, one or more of the films (preferably each film) has a thickness of from 5 to 30 μm. The optional or preferred thicknesses mentioned above in relation to the film of the first aspect apply equally to the film of the third aspect. Preferably, the thickness of the article and its mechanical properties (tensile strength, modulus, etc.) are as defined in relation to the first aspect. Preferably, the article has a tensile strength that is at least 10% higher, more preferably at least 20% higher, even more preferably at least 30% higher than an otherwise identical article that does not contain silicon dioxide nanoparticles. Preferably, the article has a modulus at 300% elongation that is within 10%, preferably within 5%, of the modulus of an identical article but without the silicon dioxide nanoparticles. Preferably, the article has a modulus at 500% elongation that is within 10%, preferably within 5%, of the modulus of an identical article but without the silicon dioxide nanoparticles.

[0038] According to a fourth aspect, the present invention provides a condom comprising a laminate, the laminate comprising a plurality of elastomeric films and one or more interface surfaces, each pair of adjacent elastomeric films defining one of the interface surfaces; At least one of the plurality of elastomeric films comprises polyurethane; the laminate comprises silicon dioxide nanoparticles, and At least 60% by weight of the silicon dioxide nanoparticles are present at one or more of the interfaces defined at least in part by the film comprising polyurethane; Provide condoms. Each of the optional or preferred features described in relation to the polyurethane of the first aspect also applies to the polyurethane of the third and fourth aspects, unless the context requires otherwise. Each of the optional or preferred features described in relation to the continuous polymers ("first polymer", "second polymer", etc.) of the first aspect also applies to the continuous polymers of the films of the third and fourth aspects, unless the context requires otherwise. In embodiments in which the polymer present in one or more of the films is polyisoprene derived from natural rubber latex, the film in which it is present is considered to be a "natural rubber latex film".

[0039] In some embodiments (the fourth aspect, or in the case of the third aspect, where the article is a condom), the condom further comprises a finishing powder on one or more surfaces thereof. The one or more surfaces may be the inner surface and / or the outer surface, preferably the inner surface and the outer surface. Suitable finishing powders and means for applying same are disclosed in relation to the first aspect. In some embodiments (the fourth aspect, or in the case of the third aspect, where the article is a condom), the condom further comprises a lubricant on one or more surfaces thereof. The one or more surfaces may be the inner and / or outer surface of the condom, preferably at least the outer surface. Suitable lubricants are described in relation to the first aspect. According to a fifth aspect, the present invention provides a sealed package containing a condom according to the second, third or fourth aspect. The sealed package is preferably as described in relation to the first aspect. Some particularly preferred embodiments of the first and fourth aspects of the invention will now be described.

[0040] In certain preferred embodiments, the present invention provides a method for preparing a condom, comprising the steps of: (i) providing an aqueous coating composition comprising polyurethane and discrete silicon dioxide nanoparticles; (ii) coating a substrate with an aqueous coating composition to form a first film on the substrate; (iii) coating the first film with an aqueous coating composition to form a second film on the first film; (iv) optionally coating the second film with an aqueous coating composition to form a third film on the second film; and (v) removing the substrate to provide a condom, or removing the substrate to provide a laminate and forming a condom from the laminate. The present invention provides a method comprising:

[0041] In certain preferred embodiments, the present invention provides a condom comprising a laminate, the laminate comprising N elastomeric films and N-1 interface surfaces, each adjacent pair of elastomeric films defining one of the interface surfaces, where N is at least 2, preferably 2 to 4; Each elastomeric film comprises a polyurethane, preferably the same polyurethane; the laminate comprises silicon dioxide nanoparticles, and At least 60% by weight of the silicon dioxide nanoparticles are present at one or more of the interfaces; Provide condoms. In certain preferred embodiments, the present invention provides a condom comprising a laminate, the laminate comprising two elastomeric films defining an interface therebetween; Each elastomeric film comprises a polyurethane, preferably the same polyurethane; the laminate comprises silicon dioxide nanoparticles, and At least 60% by weight of the silicon dioxide nanoparticles are present at the interface; Provide condoms.

[0042] In certain preferred embodiments, the present invention provides a condom comprising a laminate, the laminate comprising a first elastomeric film, a second elastomeric film, and a third elastomeric film; the first elastomeric film and the second elastomeric film define a first interface, and the second elastomeric film and the third elastomeric polyurethane film define a second interface; Each elastomeric film comprises a polyurethane, preferably the same polyurethane; the laminate comprises silicon dioxide nanoparticles; At least 60% by weight of the silicon dioxide nanoparticles are present at the first interface or the second interface; Provide condoms. In each of the particularly preferred embodiments discussed above, each film preferably has the same chemical composition. The invention will now be described with reference to the following non-limiting drawings. [Brief description of the drawings]

[0043] [Figure 1] 1A-1C are graphs showing the tensile and burst properties of condoms prepared according to Example 1, as measured according to Example 2. Data points on each graph are, from left to right, for a control formulation (U228), 1 wt. % SiO2, 2 wt. % SiO2, and 3 wt. % SiO2. In FIG. 1A, the bars represent the breaking force (N, left axis) and the lines represent the thickness (μm, right axis). In FIG. 1B, the bars represent the tensile strength (MPa, left axis) and the lines represent the breaking elongation (%, right axis). In FIG. 1C, the left bar represents the modulus at 300% elongation (MPa) and the right bar represents the modulus at 500% elongation (MPa). In FIG. 1D, the right bar represents the burst volume (L) and the left bar represents the burst pressure (kPa). [Diagram 2]2A-C are graphs showing the tensile and burst properties of condoms prepared according to Example 3, measured according to the method disclosed in Example 2, compared to the 2 wt. % SiO2 and control condoms of Example 1. Data points on each graph are, from left to right, for a control formulation (U228) with a 26.3 μm wall thickness, a 2 wt. % SiO2 with a 24.8 μm wall thickness, and a 2 wt. % SiO2 with a 20.0 μm wall thickness. In FIG. 2A, the bars represent the breaking force (N, left axis) and the line graph represents the thickness (μm, right axis). In FIG. 2B, the bars represent the tensile strength (MPa, left axis) and the line graph represents the breaking elongation (%, right axis). In FIG. 2C, the left bar represents the modulus (MPa) at 300% elongation and the right bar represents the modulus (MPa) at 500% elongation. In FIG. 2D, the right bar represents the burst volume (L) and the left bar represents the burst pressure (kPa). EXAMPLES

[0044] The invention will now be described with reference to the following non-limiting examples. Example 1 An aqueous aliphatic polyether polyurethane dispersion (Alberdingk® U228 (50% solids), commercially available from Alberdingk Boley) was diluted to 35% solids with deionized water and mixed with an aqueous carbodiimide crosslinker (Carbodilite® SV-02 (40% solids), commercially available from Nisshinbo Chemical) in an amount of 3% solid carbodiimide by weight based on the total solids of the diluted polyurethane dispersion. The resulting mixture was stirred for 30 minutes. 363 ml of 10 ... 2 Ludox® SM colloidal silica (SiO nanoparticles in a 30 wt% suspension in H2O, commercially available from Sigma-Aldrich) having a surface area of ​​100 μg / g was added in an amount of 1 wt%, 2 wt%, or 3 wt% solids based on the weight of the solid polyurethane, the resulting mixture was stirred for 30 minutes, and then sonicated for 30 minutes. A liquid polyether-modified siloxane surfactant (BYK-348, commercially available from BYK) was added in an amount of 0.2% w / v, and the resulting mixture was stirred for 30 minutes.

[0045] Condoms were prepared by dipping a glass former into the mixture three times using a dipping robot to form three layers of material on the former. Between each dipping step, the material was dried on the former in a circulating oven at 60 °C for 5 minutes to form a film. After the final film-forming step, the material was dried on the former in another circulating oven at 120 °C for 12 minutes. After cooling to room temperature, a starch-based finishing slurry was applied and the condom was peeled off the glass former and dried in a dryer. The wall thickness of the three-layer condom was 25-30 μm. A control was prepared in the same manner as above, without the addition of colloidal silica or surfactant.

[0046] The sample formulations are summarized in the table below: [Table 1] The addition of colloidal silica was found to have no noticeable effect on the appearance of the condoms: all condoms appeared clear after the starch-based finishing powder was removed.

[0047] Example 2 The tensile properties (break force, tensile strength, break elongation, modulus) and air burst properties (burst pressure, burst volume) of condom samples obtained from condoms prepared according to Example 1 were determined. To determine the tensile properties, ring-shaped specimens were cut from each condom before testing in a universal tensile tester according to ISO 4074. The specimens were tested using a 500 N load cell and stretched at a rate of 500 mm / min until break. Tensile stress was calculated by taking the ratio of force to the initial cross-sectional area of ​​the specimen. Strain or elongation was defined as the ratio of the stretched length to the initial length of the specimen. Elastic modulus was defined as the stress at a specific elongation, e.g., the elastic modulus at 300% elongation (M300) and the elastic modulus at 500% elongation (M500) are referred to as the stress at 300% elongation and 500% elongation, respectively. The force, elongation, and stress at break were defined as the breaking force, breaking elongation, and tensile strength, respectively. Five replicate measurements were performed on each specimen and average values ​​were calculated for all properties.

[0048] The thickness of each condom (i.e., wall thickness excluding the bead) was measured perpendicular to the length of the condom while the condom was unfolded and lying flat with no creases. The thickness of each sample condom was measured three times with a thickness gauge and an average value was determined. The burst pressure and burst volume of condom samples were assessed by inflating the condom like a balloon and measuring the air pressure and air volume, respectively, required to burst it, in accordance with ISO 23409:2011. The condom was unfolded and secured to a stem, leaving approximately 150mm of space to be inflated. The test apparatus inflated the condom with clean, oil- and moisture-free air at the specified rate.

[0049] The results are shown in Table 2 and Figures 1A to 1D. [Table 2] The addition of SiO2 nanoparticles to the formulation was found to significantly increase the break force and tensile strength of the condom samples. However, the addition of SiO2 nanoparticles resulted in limited differences in the modulus at 300% elongation, modulus at 500% elongation, break elongation, burst pressure, or burst volume. It is noteworthy that the tensile strength peaked at 2 wt% SiO2. It is believed that increasing the SiO2 further increases the ductility of the material, ultimately decreasing its tensile strength. However, it can be seen that the tensile strength of the 3 wt% SiO2 condom was still significantly higher than the control.

[0050] Example 3 Condoms were also prepared using the 2 wt. % SiO2 formulation of Example 1 in the same manner as disclosed in Example 1, with a thinner wall thickness than the 2 wt. % SiO2 condom of Example 1 (20 μm versus 25 μm). Physical properties were measured according to Example 2. The results are shown in Table 3 and Figures 2A-2D. For comparison, the 2% SiO2 condoms of Examples 1 and 2 and a control condom were included. [Table 3]

[0051] The 20 μm thick condom sample with 2% SiO2 by weight had a lower breaking force than the comparable 25 μm thick sample and the 26 μm thick control sample; however, it was still within the acceptable range for a condom. Additionally, the tensile strength of the 20 μm thick condom sample with 2% SiO2 by weight was higher than the control sample, and the modulus at 300% elongation and 500% elongation were similar. The burst pressure of the 20 μm thick condom sample with 2% SiO2 by weight was slightly lower than the other two samples, but still within the acceptable range. Overall, the data indicate that the inclusion of SiO2 nanoparticles in the formulation can reduce condom thickness while maintaining acceptable physical properties.

[0052] Example 4 To investigate the surface morphology of the condom samples, scanning electron microscope (SEM) images were taken of samples cut from condoms prepared according to Example 1. Cross-sectional samples were prepared by cutting each sample into small pieces and immersing them in liquid nitrogen for 1 minute, followed by immediately fracturing the samples. The samples were placed on a sample stub before being coated with gold under vacuum. Finally, the sample grids were subjected to surface micrograph analysis using a field emission scanning electron microscope (FE-SEM). SEM micrographs were taken at 5000x, 10000x, and 25000x magnification. In the samples containing SiO2, SiO2 nanoparticles were found at the interface between the polyurethane layers. This provides evidence of the ability of SiO2 nanoparticles to migrate to the air-water interface during each coating step and remain at the interface as successive films are formed. At 1 wt% SiO2, the concentration of SiO2 nanoparticles dispersed in the bulk of the polyurethane matrix is ​​very low. At 2 wt% and 3 wt% SiO2, the concentration of SiO2 nanoparticles dispersed in the bulk of the polyurethane matrix increases.

[0053] Example 5 Scanning electron microscopy (SEM) was used along with energy dispersive X-ray analysis (EDX) on the samples imaged in Example 4 to examine the elements distributed in the polyurethane matrix. The condom samples without SiO2 contained mainly C and O as the main components of polyurethane. However, in the samples with SiO2, the Si component could be observed, which points to the presence of SiO2. The SEM-EDX micrographs clearly showed that the Si-containing particles were mainly present at the interface between the polyurethane layers. The SEM-EDX micrographs show further evidence that discrete SiO2 nanoparticles are able to migrate to the interface between the films resulting from each dipping step. The foregoing detailed description has been provided for purposes of explanation and illustration, and is not intended to limit the scope of the appended claims. Many variations in the presently preferred embodiments illustrated herein will be apparent to those skilled in the art that remain within the scope of the appended claims and their equivalents.

Claims

1. A method for preparing an elastomer laminate article or condom, (i) A step of preparing a first aqueous coating composition comprising a first polymer and discrete silicon dioxide nanoparticles, wherein the first polymer is polyurethane; (ii) A step of preparing a second aqueous coating composition comprising a second polymer; (iii) A step of coating a substrate with a first aqueous coating composition to form a first film on the substrate; (iv) A step of coating the first film with a second aqueous coating composition to form a second film on the first film; and (v) Step to remove the substrate The method comprising the above.

2. The method according to claim 1, wherein the second polymer is selected from polyisoprene, polyurethane, and mixtures thereof.

3. The method according to claim 2, wherein the second polymer is polyurethane, or the first polymer and the second polymer are the same polyurethane, or the first aqueous coating composition and the second aqueous coating composition are the same.

4. The method according to claim 1, wherein the volume-weighted average particle diameter (D4,3) of discrete silicon dioxide nanoparticles, as measured by dynamic light scattering, is 1 to 100 nm, 2 to 50 nm, 4 to 20 nm, or 5 to 10 nm.

5. Discrete silicon dioxide nanoparticles are present in a quantity of at least 200 m 2 / g, at least 250m 2 / g, or at least 300m 2 The method according to claim 1, having a BET surface area of ​​1 / g.

6. The method according to claim 1, wherein the discrete silicon dioxide nanoparticles contain surface silanol groups.

7. The method according to claim 1, wherein the step of preparing a first aqueous coating composition comprising a first polymer and discrete silicon dioxide nanoparticles comprises combining a source of the first polymer with a source of discrete silicon dioxide nanoparticles to form the first aqueous coating composition.

8. The method according to claim 7, wherein the first source of the polymer comprises an aqueous polyurethane dispersion and / or the source of the discrete silicon dioxide nanoparticles is colloidal silica.

9. The method according to claim 8, wherein the colloidal silica is an aqueous dispersion with a pH of 7 to 11 or a pH of 8 to 10.

10. The method according to claim 1, wherein the first aqueous coating composition contains discrete silicon dioxide nanoparticles in an amount of 0.1 to 3% by mass, 0.2 to 4% by mass, 0.3 to 2% by mass, or 0.5 to 1% by mass.

11. The method according to claim 1, wherein the first aqueous coating composition contains a first polymer and discrete silicon dioxide nanoparticles, and the mass ratio of the first polymer to the discrete silicon dioxide nanoparticles is 5:1 to 200:1, 10:1 to 200:1, 20:1 to 150:1, or 40:1 to 80:

1.

12. The method according to claim 1, further comprising the steps of preparing a third aqueous coating composition comprising a third polymer, coating a first film with a second aqueous coating composition to form a second film on the first film, and removing a substrate, in between these steps, the step of coating the second film with a third aqueous coating composition to form a third film on the second film.

13. A condom obtained or obtainable by the method described in claim 1.

14. An elastomerized laminate article comprising multiple polymer films and one or more interfaces, wherein each adjacent pair of films defines one of the interfaces. At least one of the multiple polymer films contains polyurethane, The laminate contains silicon dioxide nanoparticles, and At least 60% by mass of silicon dioxide nanoparticles are present at one or more interfaces that are at least partially defined by a film containing polyurethane. The aforementioned article.

15. A condom comprising a laminate, wherein the laminate comprises a plurality of elastomer films and one or more interfaces, and each adjacent pair of elastomer films defines one of the interfaces. At least one of the multiple elastomer films contains polyurethane, The laminate contains silicon dioxide nanoparticles, and At least 60% by mass of silicon dioxide nanoparticles are present at one or more interfaces that are at least partially defined by a film containing polyurethane. The aforementioned condom.

16. An elastomerized laminate article according to claim 14, or a condom according to claim 15, wherein at least 70% by mass, or at least 80% by mass, of silicon dioxide nanoparticles are present at one or more interfaces.

17. A sealed package comprising a condom according to any one of claims 13, 15, or 16.

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