A method for preparing a high-uniformity ultrathin waterborne polyurethane condom

Abstract

This invention belongs to the field of contraceptive manufacturing technology, specifically a method for preparing a highly uniform, ultra-thin waterborne polyurethane condom. The method includes: preparing a waterborne polyurethane emulsion with a solid content of 15-30%; impregnating the insulating layer emulsion; immersing a treated mold in the waterborne polyurethane emulsion, then drying it, repeating this process 2-3 times to obtain a waterborne polyurethane film on the mold surface; and then performing operations such as edge rolling, baking, and demolding to obtain the waterborne polyurethane condom product. This method is simple, safe, and easy to control; it can obtain ultra-thin waterborne polyurethane condoms of the 001 and 002 series. The prepared condoms have advantages such as ultra-thinness, uniform thickness distribution, non-allergenicity, high strength, and good softness.

Description

Technical Field

[0001] This invention belongs to the field of contraceptive manufacturing technology, specifically relating to a method for preparing waterborne polyurethane condoms. Background Technology

[0002] Condoms, also known as safety condoms, are a simple way to prevent pregnancy without medication. They also help prevent the transmission of sexually transmitted infections such as gonorrhea and HIV. Condoms are typically made from natural latex, which contains allergenic water-soluble proteins. Although the natural latex used to make condoms undergoes a protein removal process, small amounts of allergenic water-soluble proteins still remain. Approximately 8% of the population is allergic to latex.

[0003] Waterborne polyurethane material has good biocompatibility. Condoms made of waterborne polyurethane have advantages over natural latex condoms, such as being non-toxic, having high toughness and strength, and good thermal conductivity. They can be made with an ultra-thin thickness of 0.01~0.03mm, reducing the feeling of barrier during use and increasing user pleasure. In addition, the structure of waterborne polyurethane film is more compact, providing better barrier properties against sperm, HIV, hepatitis B virus, etc.

[0004] Because waterborne polyurethane materials have many polar groups in their molecular chain structure and are highly polar, when using highly polar materials such as glass molds as production molds, the product has high adhesion to the mold surface after molding, making it inconvenient to demold. Demolding is particularly difficult on industrial production lines, often damaging the integrity of the product film or causing permanent deformation of the product film, resulting in a product qualification rate of only about 70-80%.

[0005] Commercially available polyurethane condoms typically have an average film thickness of approximately 0.019-0.028 mm. The thickness gradually increases from the thinnest part at the open end (rolled edge) to the closed end (reservoir). According to the thickness test methods of HT / T5456-2018 or GB / T7544 idtISO4074 standards, the thickness at 35 mm from the closed end is about 10-20% thicker than at 35 mm from the open end. Users will notice the thicker part of the film more, affecting their comfort. A typical example is a film thickness of 26 mm at 35 mm from the closed end and 21 mm at 35 mm from the open end. Summary of the Invention

[0006] To overcome the shortcomings of the prior art, the present invention provides a method for preparing a highly uniform ultrathin waterborne polyurethane condom.

[0007] The method for preparing a high-uniformity ultra-thin waterborne polyurethane condom provided by this invention comprises the following steps:

[0008] S1: Adjust the waterborne polyurethane emulsion to a solid content of 15-30% and a viscosity of 15-30 mPa·s;

[0009] S2: Mold cleaning: Clean the glass mold with a special cleaning solution, rinse with deionized water, and dry. The cleaning solution includes, but is not limited to, 2-10% caustic soda solution, 1-8% dilute acid solution, and 1-10% neutral cleaning solution.

[0010] S3: Impregnation with release agent emulsion: Immerse the mold in the release agent emulsion for 3 to 10 seconds, lift the mold slowly at a lifting speed of 2.0-3.0 mm / s, and then dry at 65-100℃ for 2-6 minutes.

[0011] The isolation layer emulsion is a modified waterborne polyurethane emulsion with a solid content of 3-8%. It is prepared by compounding organosilicon modified waterborne polyurethane emulsion, nano-silica modified polyether waterborne polyurethane emulsion, wetting agent, leveling agent and defoamer and then filtering through a 400-mesh filter.

[0012] S4: Impregnation film formation: Under conditions of relative humidity above 80%, immerse the mold treated in step S3 into the aqueous polyurethane emulsion prepared in step S1 for 3 to 10 seconds. Then, gently remove the mold at an upward speed of 2.0 to 3.0 mm / s and dry it at 65 to 110℃ for 3 to 8 minutes. Repeat step S4 treatment 2 to 4 times to obtain an aqueous polyurethane film on the surface of the mold.

[0013] S5: Edge curling: The open end of the water-based polyurethane film on the mold surface is curled.

[0014] S6: Baking: Place the mold processed in step S5 into an oven and bake at 70-120℃ for 15-30 minutes.

[0015] S7: Impregnation release agent: Immerse the mold treated in step S6 into a special release agent with a solid content of 1-8%, and then dry it at 80-110℃ for 6-15 minutes.

[0016] S8: Demolding: Demolding the mold processed in step S7 is performed using a brush roller or a rubber roller to obtain the semi-finished water-based polyurethane condom.

[0017] S9: Electrical Inspection: The semi-finished water-based polyurethane condoms obtained in step S8 are subjected to high-voltage dry electrical inspection to remove defective products, thus obtaining qualified water-based polyurethane condom products.

[0018] Preferably, the waterborne polyurethane emulsion in step S1 is a polyether / polyester type waterborne polyurethane emulsion with high strength, low modulus, and high resilience. More preferably, it has a 100% Young's modulus of 0.9 to 1.3 MPa, a tensile strength of 45 MPa or more, and a permanent deformation of less than 5%.

[0019] Preferably, the cleaning solution in step S2 includes, but is not limited to, 2-10% caustic soda solution, 1-8% dilute acid solution, and 1-10% neutral cleaning solution.

[0020] Preferably, the wetting agent and leveling agent used in the isolation layer emulsion in step S3 are polyether-modified polysiloxane polymers, and the defoamer used is a polyether-modified polysiloxane solution, with an addition amount of 0.05-0.2%.

[0021] Preferably, the special release agent in step S7 is one or two of the following: aqueous dispersion of silica, aqueous dispersion of modified corn starch, aqueous dispersion of ultrafine calcium carbonate, and aqueous dispersion of cellulose.

[0022] Preferably, the water-based polyurethane condom product that has passed the electrical test is then heat-sealed with the addition of a lubricant. The lubricant is either silicone oil or a water-based lubricant, preferably super-slippery silicone oil or hyaluronic acid water-based lubricant.

[0023] In this invention, the average thickness difference between the closed end (35mm) and the open end (35mm) of the condom does not exceed 6.5%, which meets the requirement of high uniformity.

[0024] Using the modified aqueous polyurethane emulsion of the present invention as an isolation layer emulsion has the following advantages:

[0025] (1) Due to the polarity of the molecular chain groups of waterborne polyurethane materials, when using non-polar or weakly polar materials as molds for impregnation and film formation, such as polypropylene (PP), polyethylene terephthalate (PET), polytetrafluoroethylene, etc., the high hydrophobicity of the mold surface results in poor emulsion spreading and film formation on the mold surface and poor film uniformity, which reduces the product qualification rate. When using molds made of materials such as stainless steel and glass, the strong bonding force between the polyurethane film and the mold surface makes it difficult to demold the product after molding. Using the modified waterborne polyurethane emulsion of the present invention as the isolation layer emulsion, since it is a silicone-modified waterborne polyurethane emulsion and a nano-silica-modified polyether polyurethane emulsion, the siloxy groups contained significantly reduce the bonding force between the film and the mold, that is, the adhesion of the film on the glass mold surface is effectively reduced. In industrial continuous production, it is easy to roll and demold without damaging the product film, which significantly improves the product qualification rate. The product qualification rate is greatly increased to over 95%, reducing the overall production cost.

[0026] (2) According to the preparation method of this high uniformity ultra-thin waterborne polyurethane condom, due to the suitable matching degree between the emulsion solid content, viscosity characteristics and the mold lifting speed (2.0-3.0 mm / s) after impregnation, the mold lifting speed during specific production is determined according to the following formula:

[0027] V=C*δ / (∑TS i *μ i ), where i is 1, 2, 3 or 1, 2, 3, 4;

[0028] V --- Lifting speed, m / s;

[0029] C --- A specific relationship constant related to the properties of the emulsion and the mold, whose value was determined experimentally to be 9.725*10. 3 ;

[0030] δ---Thickness of a single layer of the product, in mm;

[0031] TS --- Total solids content of the polyurethane emulsion in the glue tank, %

[0032] μ --- Viscosity of the polyurethane emulsion in the glue tank, mPa·s;

[0033] The ultra-thin waterborne polyurethane condoms produced by impregnation have a very uniform thickness distribution of the adhesive film. When tested using the 3-point method of the thickness test method in HT / T5456-2018 or GB / T7544 idt ISO4074 standard, the average thickness difference between the closed end and the open end at 35mm does not exceed 6.5%. Under stable conditions, the typical average thickness difference does not exceed 3.5%.

[0034] The method of this invention is simple, safe, and easy to control. Using this method, highly uniform ultra-thin waterborne polyurethane condoms of the 001 and 002 series can be obtained. In addition to the general advantages of polyurethane condoms such as ultra-thinness, safety, non-allergenicity, and good thermal conductivity, these condoms particularly exhibit advantages such as uniform film thickness distribution, high tear strength, good softness (low modulus), and high yield. Typical product performance data compared with commercially available samples are as follows:

[0035] .

[0036] The testing methods for the main performance of the product are as follows:

[0037] (1) Tensile property test: The test was conducted using a universal tensile testing machine and according to the method described in GB / T 528—2009. The sample was a dumbbell-shaped sheet, the tensile rate was 300 mm / min, and the temperature was 25℃.

[0038] (2) Tear strength test: The test was conducted using a universal tensile testing machine and according to the method described in GB / T 528—2009. The sample was a right-angled specimen, the tensile rate was 500±50 mm / min, and the temperature was 25℃.

[0039] (3) Puncture strength test: According to the standard GB / T10004-2008, the sample film is cut into strips with scissors, and the width of the strip film must be greater than 100X100mm; the 100mm wide test piece is installed on the sample film fixing ring, and then a steel needle with a diameter of 1.0mm and a diameter tip radius of 0.1mm is used to puncture at a speed of (50±5)mm / min. The maximum load of the steel needle penetrating the test piece is read; the test is generally performed at 3 points and the arithmetic mean is taken.

[0040] (4) The thickness of the adhesive film was measured using the thickness gauge method in Appendix F of GB / T7544-2019 standard (Shanghai Liuling Instrument Factory);

[0041] 5. Viscosity was measured at 25℃ using an NDJ-1 type rotational viscometer;

[0042] (5) The burst performance of the product shall be tested by the method in Appendix H of the HT / T5456-2018 standard. Detailed Implementation

[0043] The preferred embodiments of the present invention are described below. It should be understood that the preferred embodiments described herein are for illustration and explanation only and are not intended to limit the present invention.

[0044] Example 1

[0045] S1: Condoms are formulated with water-based polyurethane emulsion.

[0046] Deionized water was added to the waterborne polyurethane emulsion under stirring to dilute it to a solid content of 18.5%, and stirred for 20 minutes. The diluted emulsion was then filtered through a 400-mesh filter cloth and placed in emulsion impregnation tanks No. 1, 2, and 3 respectively, and allowed to stand for 24 hours before use. The viscosity of the emulsion was measured to be 140 mPa·s using a rotational viscometer. The waterborne polyurethane emulsion is a polyether / polyester type waterborne polyurethane emulsion with high strength, low modulus, and high resilience.

[0047] S2: Mold cleaning:

[0048] The mold is a glass mold, fixed on a fixture. Under production conditions, the mold is first cleaned with a soft brush and neutral detergent at room temperature, then cleaned with a soft brush and deionized water at room temperature, and finally cleaned with (50±5)℃ ultrapure water (conductivity of 0.1~0.2us / cm). Then it is put into an oven for drying at 75~80℃ for 2~3 minutes.

[0049] S3: Impregnated isolation layer emulsion

[0050] After drying in step S2, the mold is cooled to 38-40°C through a constant temperature air duct and immersed in the isolation layer emulsion for 3-5 seconds. The mold is then slowly removed at a lifting speed of 2.0 mm / s and placed in an oven to dry at 65-70°C for 5-6 minutes.

[0051] S4: Impregnation film formation:

[0052] After the mold is processed in step S3, it is cooled to 38-40°C through a constant temperature air duct and immersed in the No. 1 emulsion impregnation tank for 3-5 seconds. The mold is then slowly removed at a lifting speed of 2.0 mm / s. After removal, it is sprayed with humidifier for 20 seconds and then put into an oven to dry at a temperature of 65-70°C for 7-8 minutes.

[0053] This is one immersion; this step is repeated 3 times.

[0054] S5: Curled edge:

[0055] After step S4, a water-based polyurethane film is formed on the mold surface. The open end of the film on the mold surface is rolled with a rubber roller, and the total length after rolling is ≥180 mm.

[0056] S6: Baking: Place the mold processed in step S5 into an oven and bake at a temperature of 110-120°C for 15-18 minutes.

[0057] S7: Impregnation release agent: Immerse the mold treated in step S6 into a special release agent (nano silica) with a solid content of 3%, take it out and dry it at 80-85℃ for 13-15 minutes;

[0058] S8: Demolding: Demolding the mold processed in step S7 is performed using a brush roller or a rubber roller to obtain the semi-finished water-based polyurethane condom.

[0059] S9: Electrical Inspection: The semi-finished water-based polyurethane condoms obtained in step S8 are subjected to high-voltage dry electrical inspection to remove defective products, thus obtaining qualified water-based polyurethane condom products.

[0060] The selected waterborne polyurethane emulsion is a polyether / polyester type waterborne polyurethane emulsion with high strength, low modulus, and high resilience, with a 100% Young's modulus of 1.2 MPa, a tensile strength of 48.3 MPa, and a permanent deformation of 2.2%.

[0061] Preparation of the isolation layer emulsion: The isolation layer emulsion is a 5% solid content compound modified waterborne polyurethane emulsion. Take 10 kg of 25% solid content nano-silica modified polyether waterborne polyurethane emulsion and 5 kg of 50% organosilicon copolymer modified waterborne polyurethane emulsion and add them to 84.6 kg of deionized water. Add 0.15 kg of wetting agent, 0.15 kg of leveling agent and 0.1 kg of defoamer to it. Then stir it to make it uniform and filter it through a 400 mesh filter.

[0062] Preparation of the release agent: Add 3 kg of silica (nano silica) and 0.5 kg of water-based wetting agent to 96.3 kg of deionized water, then add 0.2 kg of surfactant and stir until homogeneous. The purpose of adding the water-based wetting agent is to improve the uniformity of silica flow on the film surface. Polyether-modified organosilicon wetting agents can be selected as the water-based wetting agent.

[0063] The polyurethane condom obtained in this embodiment has a thickness of 0.016 mm, a tensile strength of 50.15 MPa, an elongation at break of 1068%, a 100% modulus of elongation of 1.19 MPa, a 300% modulus of elongation of 2.41 MPa, and a 93.2% pass rate after high-voltage electrical testing of the semi-finished product.

[0064] Example 2

[0065] S1: Condoms are prepared using water-based polyurethane emulsions.

[0066] Deionized water was added to the aqueous polyurethane emulsion under stirring to dilute it to a solid content of 20.5%, and stirred for 20 minutes. The diluted emulsion was then filtered through a 400-mesh filter cloth and placed in emulsion impregnation tanks No. 1, 2, and 3 respectively, and allowed to stand for 24 hours before use. The viscosity of the emulsion was measured to be 140 mPa·s using a rotational viscometer. The aqueous polyurethane emulsion is a polyether / polyester type aqueous polyurethane emulsion with high strength, low modulus, and high resilience.

[0067] S2: Mold cleaning:

[0068] The mold is a glass mold, fixed on a fixture. Under production conditions, the mold is first cleaned with a soft brush and 2-5% alkaline solution at room temperature, then cleaned with a soft brush and deionized water at room temperature, and finally cleaned with (55±5)℃ ultrapure water (conductivity of 0.1-0.2us / cm). Then it is put into an oven for drying at 80-85℃ for 2-3 minutes.

[0069] S3: Immersion in the release agent tank

[0070] After drying in step S2, the mold is cooled to 43-45°C through a constant temperature air duct, immersed in a release agent, and then placed in an oven to dry at a temperature of 75-80°C for 4-5 minutes.

[0071] S4: Impregnation film formation:

[0072] After the mold is processed in step S3, it is cooled to 45°C through a constant temperature air duct and immersed in the No. 1 emulsion impregnation tank for 3 to 5 seconds. The mold is then slowly removed at a lifting speed of 2.07 mm / s. After removal, it is sprayed with humidifier for 20 seconds and then put into an oven to dry at a temperature of 75 to 80°C for 5 to 6 minutes.

[0073] This is one immersion; this step is repeated 3 times.

[0074] S5: Curled edge:

[0075] After step S4, a water-based polyurethane film is formed on the mold surface. The open end of the film on the mold surface is rolled with a rubber roller, and the total length after rolling is ≥185 mm.

[0076] S6: Baking: Place the mold processed in step S5 into an oven and bake at a temperature of 85-95°C for 22-25 minutes.

[0077] S7: Impregnation release agent: Immerse the mold treated in step S6 into a special release agent (ultrafine calcium carbonate) with a solid content of 2.5%, take it out and dry it at 90-95℃ for 10-12 minutes;

[0078] S8: Demolding: Demolding the mold processed in step S7 is performed using a brush roller or a rubber roller to obtain the semi-finished water-based polyurethane condom.

[0079] S9: Electrical Inspection: The semi-finished water-based polyurethane condoms obtained in step S8 are subjected to a 1600V high-voltage dry electrical inspection to remove defective products, thus obtaining qualified water-based polyurethane condom products.

[0080] The selected waterborne polyurethane emulsion is a polyether / polyester type waterborne polyurethane emulsion with high strength, low modulus, and high resilience, with a 100% Young's modulus of 1.2 MPa, a tensile strength of 52.6 MPa, and a permanent deformation of 2.1%.

[0081] Preparation of the isolation layer emulsion: The isolation layer emulsion is a 6% solid content compound modified waterborne polyurethane emulsion. Take 10 kg of 30% solid content nano-silica modified polyether waterborne polyurethane emulsion and 7.5 kg of 40% organosilicon graft modified waterborne polyurethane emulsion and add them to 82.1 kg of deionized water. Add 0.18 kg of wetting agent, 0.12 kg of leveling agent and 0.1 kg of defoamer to it. Then stir it to make it uniform and filter it through a 400 mesh filter.

[0082] Preparation of the release agent: Add 2.5 kg of ultrafine light calcium carbonate, 0.5 kg of ultrafine light magnesium carbonate, and 0.1 kg of water-based wetting agent to 96.75 kg of deionized water, then add 0.15 kg of surfactant and stir until homogeneous. The purpose of adding the water-based wetting agent is to improve the uniformity of ultrafine light calcium carbonate flow on the film surface. A polyether-modified organosilicon wetting agent can be selected as the water-based wetting agent.

[0083] The polyurethane condom obtained in this embodiment has a thickness of 0.0194 mm, a tensile strength of 52.06 MPa, an elongation at break of 1178%, a 100% modulus of elongation of 1.16 MPa, a 300% modulus of elongation of 2.31 MPa, and a 94.5% pass rate after high-voltage electrical testing of the semi-finished product.

[0084] Example 3

[0085] S1: Condoms are prepared using water-based polyurethane emulsions.

[0086] Deionized water was added to the aqueous polyurethane emulsion under stirring to dilute it to a solid content of 19.0%, and stirred for 20 minutes. The diluted emulsion was then filtered through a 400-mesh filter cloth and placed in emulsion impregnation tanks No. 1, 2, and 3 respectively, and allowed to stand for 24 hours before use. The viscosity of the emulsion was measured to be 143 mPa·s using a rotational viscometer. The aqueous polyurethane emulsion is a polyether / polyester type aqueous polyurethane emulsion with high strength, low modulus, and high resilience.

[0087] S2: Mold cleaning:

[0088] The mold is a glass mold, fixed on a fixture. Under production conditions, the mold is first cleaned with a soft brush and 1-3% alkaline solution at room temperature, then cleaned with a soft brush and deionized water at room temperature, and finally cleaned with (60±5)℃ ultrapure water (conductivity of 0.1-0.2us / cm). Then it is put into an oven for drying at 85-90℃ for 1-2 minutes.

[0089] S3: Immersion in the release agent tank

[0090] After drying in step S2, the mold is cooled to 35-37°C through a constant temperature air duct, immersed in a release agent, and then placed in an oven to dry at a temperature of 85-90°C for 3-4 minutes.

[0091] S4: Impregnation film formation:

[0092] After the mold is processed in step S3, it is cooled to 35-37°C through a constant temperature air duct and immersed in the No. 1 emulsion impregnation tank for 4-6 seconds. The mold is then slowly removed at a lifting speed of 2.75 mm / s. After removal, it is sprayed with humidifier for 15 seconds and then put into an oven for drying at 85-90°C for 3.5-4.5 minutes.

[0093] This is one immersion; this step is repeated 3 times.

[0094] S5: Curled edge:

[0095] After step S4, a water-based polyurethane film is formed on the mold surface. The open end of the film on the mold surface is rolled with a rubber roller, and the total length after rolling is ≥185 mm.

[0096] S6: Baking: Place the mold processed in step S5 into an oven and bake at a temperature of 70-80°C for 25-30 minutes.

[0097] S7: Impregnation release agent: Immerse the mold treated in step S6 into a special release agent with a solid content of 5.0% (modified corn starch release agent), take it out and dry it at 95-100℃ for 8-10 minutes;

[0098] S8: Demolding: Demolding the mold processed in step S7 is performed using a brush roller or a rubber roller to obtain the semi-finished water-based polyurethane condom.

[0099] S9: Electrical Inspection: The semi-finished water-based polyurethane condoms obtained in step S8 are subjected to a 1600V high-voltage dry electrical inspection to remove defective products, thus obtaining qualified water-based polyurethane condom products.

[0100] The selected waterborne polyurethane emulsion is a polyether / polyester type waterborne polyurethane emulsion with high strength, low modulus, and high resilience, with a 100% Young's modulus of 1.08 MPa, a tensile strength of 52.8 MPa, and a permanent deformation of 2.8%.

[0101] Preparation of the isolation layer emulsion: The isolation layer emulsion is a 3% solid content compound modified waterborne polyurethane emulsion. Take 5 kg of 30% solid content nano-silica modified polyether waterborne polyurethane emulsion and 3.75 kg of 40% organosilicon graft modified waterborne polyurethane emulsion and add them to 90.9 kg of deionized water. Add 0.15 kg of wetting agent, 0.10 kg of leveling agent and 0.1 kg of defoamer to it. Then stir it to make it uniform and filter it through a 400 mesh filter.

[0102] Preparation of the release agent: A 5% modified corn starch release agent is used. Add 4.5 kg of ultrafine modified corn starch, 0.5 kg of ultrafine light magnesium carbonate, and 0.15 kg of water-based wetting agent to 94.7 kg of deionized water, followed by 0.15 kg of surfactant, and stir until homogeneous. The purpose of adding the water-based wetting agent is to improve the uniformity of ultrafine light calcium carbonate flow on the film surface. A polyether-modified silicone wetting agent can be selected as the water-based wetting agent.

[0103] The polyurethane condoms obtained this time have a thickness of 0.023mm, a tensile strength of 53.93Mpa, an elongation at break of 1256%, a 100% modulus of elongation of 1.05Mpa, a 300% modulus of elongation of 2.09Mpa, and a pass rate of 95.1% after high-voltage electrical testing of the semi-finished products.

[0104] Example 4

[0105] S1: Condoms are prepared using water-based polyurethane emulsions.

[0106] Deionized water was added to the aqueous polyurethane emulsion under stirring to dilute it to a solid content of 22.0%, and stirred for 20 minutes. The diluted emulsion was then filtered through a 400-mesh filter cloth and placed in emulsion impregnation tanks No. 1, 2, and 3 respectively, and allowed to stand for 24 hours before use. The viscosity of the emulsion was measured to be 169 mPa·s using a rotational viscometer. The aqueous polyurethane emulsion is a polyether / polyester type aqueous polyurethane emulsion with high strength, low modulus, and high resilience.

[0107] S2: Mold cleaning:

[0108] The mold is a glass mold, fixed on a fixture. Under production conditions, the mold is first cleaned with a soft brush and 1-3% alkaline solution at room temperature, then cleaned with a soft brush and deionized water at room temperature, and finally cleaned with (65±5)℃ ultrapure water (conductivity of 0.1-0.2us / cm). Then it is put into an oven for drying at 90-95℃ for 1-2 minutes.

[0109] S3: Immersion in the release agent tank

[0110] After drying in step S2, the mold is cooled to 35-37°C through a constant temperature air duct, immersed in a release agent, and then placed in an oven to dry at a temperature of 95-100°C for 2-3 minutes.

[0111] S4: Impregnation film formation:

[0112] After the mold is processed in step S3, it is cooled to 48-50°C through a constant temperature air duct and immersed in the No. 1 emulsion impregnation tank for 3-5 seconds. The mold is then slowly removed at a lifting speed of 3.0 mm / s. After removal, it is sprayed with humidifier for 20 seconds and then put into an oven to dry at a temperature of 95-100°C for 3-4 minutes.

[0113] This is one immersion; this step is repeated twice.

[0114] S5: Curled edge:

[0115] After step S4, a water-based polyurethane film is formed on the mold surface. The open end of the film on the mold surface is rolled with a rubber roller, and the total length after rolling is ≥185 mm.

[0116] S6: Baking: Place the mold processed in step S5 into an oven and bake at a temperature of 95-105°C for 22-25 minutes.

[0117] S7: Impregnation release agent: Immerse the mold treated in step S6 into a special release agent (ultrafine calcium carbonate) with a solid content of 2.5%, take it out and dry it at 105-110℃ for 6-8 minutes;

[0118] S8: Demolding: Demolding the mold processed in step S7 is performed using a brush roller or a rubber roller to obtain the semi-finished water-based polyurethane condom.

[0119] S9: Electrical Inspection: The semi-finished water-based polyurethane condoms obtained in step S8 are subjected to a high-voltage dry electrical inspection at 1650V to remove defective products, thus obtaining qualified water-based polyurethane condom products.

[0120] The selected waterborne polyurethane emulsion is a polyether / polyester type waterborne polyurethane emulsion with high strength, low modulus, and high resilience, with a 100% Young's modulus of 1.25 MPa, a tensile strength of 55.8 MPa, and a permanent deformation of 2.5%.

[0121] Preparation of the isolation layer emulsion: The isolation layer emulsion is a modified waterborne polyurethane emulsion with a solid content of 8%. 15 kg of nano-silica modified polyether waterborne polyurethane emulsion with a solid content of 30% and 8.75 kg of organosilicon grafted modified waterborne polyurethane emulsion with a solid content of 40% are added to 75.88 kg of deionized water. Wetting agent 0.15 kg, leveling agent 0.12 kg and defoamer 0.1 kg are added to the emulsion. The mixture is then stirred until homogeneous and filtered through a 400-mesh filter.

[0122] Preparation of the release agent: An 8% suspension of a special release agent is used, composed of fumed silica and hydroxyethyl cellulose powder in a 1:3 ratio. Add 4.5 kg of ultrafine modified corn starch, 0.5 kg of ultrafine light magnesium carbonate, and 0.15 kg of water-based wetting agent to 94.7 kg of deionized water, followed by 0.15 kg of surfactant, and stir until homogeneous. The purpose of adding the water-based wetting agent is to improve the uniformity of the release agent's flow on the film surface. A polyether-modified silicone wetting agent can be selected as the water-based wetting agent.

[0123] The polyurethane condoms obtained this time have a thickness of 0.023mm, a tensile strength of 57.23Mpa, an elongation at break of 1329%, a 100% modulus of elongation of 1.22Mpa, a 300% modulus of elongation of 2.39Mpa, and a pass rate of 93.7% after high-voltage electrical testing of the semi-finished products.

[0124] More examples:

[0125] Under conditions similar to Example 4, the emulsion used for the first and second impregnations was replaced with an emulsion with a total solids content of 28% and a viscosity of 173 mPa·s. The lifting speed after impregnation was 2.6 mm / s. The resulting polyurethane condom had a thickness of 0.026 mm, a tensile strength of 58.67 MPa, an elongation at break of 1365%, a 100% modulus of elongation ... 1.25 MPa, and a 300% modulus of elongation of elongation of elongation of elongation

[0126] The main process and product performance data related to the embodiments are as follows:

[0127] .

[0128] As can be seen from the data of the above typical embodiments, it has excellent thickness distribution characteristics.

[0129] Finally, it should be noted that the above descriptions are merely preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A process for the preparation of high uniformity ultra-thin waterborne polyurethane condom characterized in that, The specific steps are as follows: S1: The aqueous polyurethane emulsion is prepared to have a solid content of 15-30% and a viscosity of 15-30 mPa.S; the aqueous polyurethane emulsion is a polyether / polyester type aqueous polyurethane emulsion; S2: mold cleaning: the glass mold is cleaned with a cleaning solution, rinsed with deionized water, and dried; the cleaning solution is 2-10% caustic lye, 1-8% dilute acid solution, and 1-10% neutral cleaning solution; S3: immersion of the release layer emulsion: the mold is immersed in the release agent emulsion for 3-10 seconds, taken out at a lifting speed of 2.0-3.0 mm / s, and then dried at 65-100°C for 2-6 min; The release layer emulsion is a 3-8% solid content compounded modified aqueous polyurethane emulsion prepared by compounding an organic silicon modified aqueous polyurethane emulsion, a nano-silica modified polyether aqueous polyurethane emulsion, a wetting agent, a leveling agent, and a defoaming agent through a 400-mesh filter; the wetting agent and the leveling agent are polyether modified polysiloxane polymers, and the defoaming agent is a polyether modified polysiloxane solution, both with an addition amount of 0.05-0.2%; specifically, 10 kg of a 25% solid content nano-silica modified polyether aqueous polyurethane emulsion, 5 kg of a 50% organic silicon copolymer modified aqueous polyurethane emulsion, 84.6 kg of deionized water, 0.15 kg of a wetting agent, 0.15 kg of a leveling agent, and 0.1 kg of a defoaming agent are added and stirred uniformly, and then filtered through a 400-mesh filter to obtain the emulsion; S4: film formation by immersion: the mold treated in step S3 is immersed in the aqueous polyurethane emulsion prepared in step S1 under the condition of a relative humidity of 80% or more, the immersion time is 3-10 seconds, the mold is taken out at a lifting speed of 2.0-3.0 mm / s, and then dried at 65-110°C for 3-8 min, and the step S4 is repeated 2-4 times to obtain an aqueous polyurethane film on the surface of the mold; S5: edge rolling: the opening end of the aqueous polyurethane film on the surface of the mold is subjected to edge rolling treatment; S6: baking: the mold treated in step S5 is placed in an oven and baked at 70-120°C for 15-30 min; S7: immersion of the release agent: the mold treated in step S6 is immersed in a special release agent with a solid content of 1-8%, taken out, and dried at 80-110°C for 6-15 min; the release agent is one or two of a white carbon black water dispersion, a modified corn starch water dispersion, an ultra-fine calcium carbonate water dispersion, and a cellulose water dispersion; S8: demolding: the mold treated in step S7 is subjected to demolding treatment by using a brush roller or a rubber roller to obtain an aqueous polyurethane condom semi-product; S9: electrical inspection: the aqueous polyurethane condom semi-product obtained in step S8 is subjected to high-voltage dry electrical inspection, and the defective products are removed to obtain qualified aqueous polyurethane condom products.

2. The production method according to claim 1, characterized by, The qualified aqueous polyurethane condom products are further added with a lubricant for heat sealing and packaging, and the added lubricant is a silicone oil or an aqueous lubricant.

3. The production method according to claim 1 or 2, characterized by, The average thickness difference between the closed end 35 mm and the opening end 35 mm of the condom is not more than 6.5%.