Preparation method of water-based polyurethane material for condoms
By preparing sulfonated alginate-reduced graphene nanomaterials and water-based polyurethane composites through electrolysis, the problem of easy adhesion and dissolution of polyester polyurethane condoms in acidic environments was solved, and the stability and mechanical properties in acidic environments were improved.
Patent Information
- Application Number
- CN202610016740.7
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2026-01-07
- Publication Date
- 2026-02-27
AI Technical Summary
Existing polyester-based polyurethane condoms tend to stick and dissolve when using protic acid lubricants, affecting safety and comfort, and they lack stability in acidic environments.
Sulfonated alginate-reduced graphene nanomaterials were prepared by electrolysis and used as functional modifiers. These nanomaterials were then combined with water-based polyurethane to form a water-based polyurethane material with excellent acid resistance and mechanical properties through in-situ reaction.
Maintaining the stability and mechanical properties of water-based polyurethane materials in an acidic environment improves the durability and safety of condoms.
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Abstract
Description
Technical Field
[0001] This invention relates to the field of polymer materials technology, specifically to a method for preparing a water-based polyurethane material for condoms. Background Technology
[0002] Natural latex condoms have become the most widely used sexual health product for contraception and prevention of sexually transmitted infections due to their abundant raw material sources and mature and simple manufacturing process. Derived from the sap of rubber trees, natural latex has a cross-linked structure formed by sulfur bonds between its molecules, giving the condom excellent elasticity, tear resistance, and stretchability, allowing it to adapt well to different size requirements. However, natural latex condoms also have some inherent limitations. Natural latex has poor tolerance to oil-based lubricants, and its strength may decrease significantly within a short period after contact. Therefore, it must be used with water-based or silicone-based lubricants, which limits its application scenarios to some extent.
[0003] Compared to natural latex, polyurethane has higher mechanical strength, so theoretically, thinner condoms can be manufactured. Currently, water-based polyester polyurethane is mainly used as the film-forming material for condoms, due to its good film density, safety, non-toxicity, and high strength. However, in the process of promoting the use of polyester polyurethane condoms, it has been found that when protic acids are used as lubricants, the hydrolysis of polyester molecules easily leads to condom sticking and dissolution, seriously affecting the safety and comfort of condom use.
[0004] Therefore, there is an urgent need to develop a protic acid-resistant water-based polyurethane material that, while ensuring the good film-forming density, safety, non-toxicity, and high strength of condoms, further enhances their tolerance to acidic environments and ensures good stability in acidic environments, thereby meeting the actual needs of condoms used in acidic environments. Summary of the Invention
[0005] Existing polyester-based polyurethane condoms suffer from problems such as easy hydrolysis of polyurethane molecules when using protic acid lubricants, leading to easy sticking and dissolution of the condom, which seriously affects the safety and comfort of condom use. This invention provides a method for preparing a water-based polyurethane material for condoms. This method can prepare a protic acid-resistant water-based polyurethane material that, while maintaining good film-forming density, safety, non-toxicity, and high strength, further enhances its resistance to acidic environments and ensures good stability in acidic conditions, thus meeting the practical needs of condoms used in acidic environments.
[0006] This invention provides a method for preparing water-based polyurethane for condoms, comprising the following preparation steps: S1, preparing a functional modifier: preparing a mixed solution of graphene oxide, alginate, and sulfonic acid as the cathode electrolyte, preparing a strong alkali solution of sulfuric acid as the anode electrolyte, wherein the cathode electrolyte and the anode electrolyte are separated by a cation exchange membrane, selecting a porous titanium mesh coated with graphene oxide as the cathode, selecting a platinum sheet as the anode, and controlling the potential of the cathode electrode relative to the saturated calomel electrode to be between -0.8 and - Within a 1.2V range, sulfonated alginate-reduced graphene nanomaterials are prepared at the cathode, wherein the sulfonated alginate-reduced graphene nanomaterials serve as functional modifiers in the preparation of water-based polyurethane; wherein the cathode chamber is an oxygen-free atmosphere, and the mass ratio of graphene oxide to sodium alginate in the electrolyte of the cathode chamber is 1:(3-5); S21, a prepolymer is prepared by mixing and reacting polymeric diol, diisocyanate, and catalyst; S22, the functional modifier prepared in S1 is made into a dispersion and added to the prepolymer for in-situ composite reaction to obtain a composite prepolymer; S23, a hydrophilic monomer is added to the composite prepolymer for hydrophilic chain extension, and after neutralization and emulsification treatment, a water-based polyurethane emulsion is obtained.
[0007] In one embodiment, in step S1, the content of oxygen-containing groups in the graphene oxide is 28-40 wt%, and the dispersion concentration of the graphene oxide in the electrolyte of the cathode chamber is 2.0-3.0 mg / mL.
[0008] In one embodiment, in S1, the alginate includes at least one of sodium alginate and potassium alginate, the carboxyl content of the alginate is 10-50 wt%, and the molecular weight of the alginate is 10,000-50,000 Da.
[0009] In one embodiment, in S1, the mass ratio of the alginate to the sulfonating agent is (3-5):(2-4), and the sulfonating agent is sodium 3-chloro-2-hydroxypropanesulfonate.
[0010] In one embodiment, in S1, the electrolysis time is 3-5 hours, and / or the electrolysis temperature is 45-55°C.
[0011] In one implementation, at least one of the following conditions is satisfied in S21:
[0012] The polymeric diol includes at least one of bio-based polycaprolactone diol, bio-based polylactic acid diol, polybutylene adipate diol, bio-based polybutylene succinate diol, and polytetrahydrofuran diol; the diisocyanate includes at least one of isophorone diisocyanate and hexamethylene diisocyanate; and the catalyst includes at least one of dibutyltin dilaurate and zinc neodecanoate.
[0013] In one embodiment, in step S22, the concentration of the functional modifier after being prepared into a dispersion is 4-8 mg / mL, and the mass ratio of the functional modifier to the prepolymer is (0.1-1):100.
[0014] In one embodiment, during the in-situ reaction in S22, a stirring operation is required, with a stirring speed of 1200-1500 rpm and a stirring time of 30-60 min.
[0015] In one embodiment, in S23, the hydrophilic monomer includes at least one of dimethylolpropionic acid and dimethylolbutyric acid, and / or the mass ratio of the hydrophilic monomer to the polymeric diol is (6-10):100.
[0016] In one embodiment, in step S23, the neutralization treatment involves adding triethylamine to adjust the degree of neutralization to 80%-90%, and / or the emulsification treatment involves adding water for homogenization and emulsification to obtain a water-based polyurethane emulsion.
[0017] The method for preparing a water-based polyurethane condom provided in this application has the following advantages:
[0018] (1) This invention prepares sulfonated alginate-reduced graphene nanomaterials by electrolysis. Electrons are transferred by an external electric field to drive the reduction reaction. No additional chemical reducing agent is required (to avoid introducing impurities). Furthermore, the three reactions of reducing graphene oxide, grafting reduced graphene with alginate, and modifying alginate with sulfonating agent can be placed in the same reaction system, which helps to reduce equipment investment and operational complexity and improve preparation efficiency.
[0019] (2) In this invention, sulfonated alginate-reduced graphene nanomaterials are used as functional additives in the preparation process of water-based polyurethane. The addition of sulfonated alginate-reduced graphene nanomaterials can not only improve the acid resistance of water-based polyurethane, but also simultaneously optimize the mechanical properties, wear resistance and biocompatibility of water-based polyurethane. Detailed Implementation
[0020] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.
[0021] To illustrate the technical solution of the present invention, specific embodiments are described below.
[0022] This invention provides a method for preparing a water-based polyurethane condom, comprising the following steps:
[0023] S1. Preparation of Functional Modifier: A mixed solution of graphene oxide, alginate, and sulfonic acid was prepared as the cathode electrolyte, and a strong alkali solution of sulfuric acid was prepared as the anode electrolyte. The cathode and anode electrolytes were separated by a cation exchange membrane. A porous titanium mesh coated with graphene oxide was selected as the cathode, and a platinum sheet was selected as the anode. The potential of the cathode electrode relative to the saturated calomel electrode was controlled between -0.8 and - Within a 1.2V range, sulfonated alginate-reduced graphene nanomaterials are prepared at the cathode. These nanomaterials serve as functional modifiers in the preparation of water-based polyurethane. The cathode chamber is in an oxygen-free atmosphere, and the mass ratio of graphene oxide to sodium alginate in the cathode electrolyte is 1:(3-5). In step S21, a prepolymer is prepared by mixing and reacting polymeric diol, diisocyanate, and catalyst. In step S22, the functional modifier obtained in step S1 is dispersed and added to the prepolymer for in-situ composite reaction to obtain a composite prepolymer. In step S23, a hydrophilic monomer is added to the composite prepolymer for hydrophilic chain extension. After neutralization and emulsification, a water-based polyurethane emulsion is obtained.
[0024] The stability of existing water-based polyurethane emulsions primarily relies on the electrostatic repulsion (electric double layer structure) formed by the hydrophilic groups (usually anionic carboxylate groups, such as carboxylate ions) on the surface of the particles dispersed in water. The introduction of protic acids (such as hydrochloric acid and acetic acid, which can dissociate into a large number of hydrogen ions) will combine with the hydrophilic groups on the particle surface, fundamentally disrupting the stability of the water-based polyurethane emulsion in water. Specifically, protic acids neutralize the negatively charged carboxylate ions on the particle surface, converting them into electrically neutral carboxylate groups with poor water solubility. This directly disrupts the electrostatic repulsion (electric double layer) that maintains emulsion stability, causing the particles to aggregate and settle due to van der Waals forces, i.e., demulsification. During demulsification, the molecular chains of the water-based polyurethane shrink and aggregate due to the decrease in hydrophilic groups, increasing intermolecular frictional resistance, which macroscopically manifests as a gradual increase in viscosity. Meanwhile, under acidic conditions, the hydrogen atoms on adjacent carbon atoms of the ether bonds in the water-based polyurethane molecular chain are easily oxidized, which may lead to molecular chain breakage and affect the rheological properties of the polyurethane system in the long run. For water-based polyurethane materials that have already formed a film, acidic media will gradually penetrate into it, not only destroying the ionic groups, but also potentially triggering chemical reactions such as hydrolysis and oxidation of the water-based polyurethane material, resulting in the material becoming sticky, softening, and losing its mechanical strength, ultimately losing its performance.
[0025] Therefore, the technical approach of this invention to solve the acid resistance of water-based polyurethane is to reduce the dependence on carboxylate groups that are easily degraded in acidic environments, and to introduce groups that can still maintain stable hydrophilic groups under acidic conditions.
[0026] Firstly, alginate is a natural linear polysaccharide extracted from brown algae. Its molecular chains consist of mannuronic acid and guluronic acid, which are tolerable to the human body. Alginate has the advantages of being non-toxic and non-allergenic. Furthermore, its molecular chains contain a large number of carboxyl and hydroxyl groups. As strongly hydrophilic groups, the carboxyl groups can ionize into carboxylate groups under neutral conditions, forming a negative charge barrier on the surface of alginate. This allows alginate to form a stable dispersion in water, making it compatible with aqueous polyurethane systems without the need for additional emulsifiers. When alginate-based functional modifier is combined with aqueous polyurethane prepolymers, interfacial delamination does not occur, ensuring the film uniformity of the aqueous polyurethane material. However, existing... Pure alginate has drawbacks such as poor acid resistance (the carboxyl group protonates to a carboxylic acid group at around pH 2), low mechanical strength, and lack of ion barrier function (it cannot resist the erosion of the polyurethane matrix by hydrogen ions in acidic lubricants). Directly using pure alginate to composite with water-based polyurethane prepolymer to prepare water-based polyurethane materials cannot directly meet the acid resistance and abrasion resistance requirements of condoms. Therefore, sulfonation modification is necessary to maintain its negative charge state in an acidic environment (pH=2), effectively preventing hydrogen ions in acidic media from penetrating into the polyurethane matrix, protecting ester and urethane bonds from hydrolysis, and ensuring the stability of water-based polyurethane in acidic environments. Furthermore, the hydroxyl and carboxyl groups on the alginate molecular chain can serve as active reaction sites, undergoing various chemical reactions such as nucleophilic substitution, esterification, and grafting. This facilitates the introduction of sulfonic acid groups as functional groups and provides sufficient contact sites for subsequent grafting and reduction of graphene.
[0027] Secondly, reduced graphene (rGO) was chosen to be grafted onto the surface of alginate instead of graphene oxide (GO) because GO has more oxygen-containing groups (epoxy and carboxyl groups), which disrupts the sp... 2 The carbon conjugated structure does not enhance mechanical properties as much as rGO. After GO is electrolytically reduced to rGO, most of the oxygen-containing groups are removed, restoring the sp... 2 The carbon-conjugated structure endows sulfonated alginate-reduced graphene nanomaterials with excellent mechanical properties, which in turn endows water-based polyurethanes with excellent mechanical properties. The small number of residual oxygen-containing groups (epoxy groups) on the rGO surface can undergo grafting reactions with alginate, while a large number of oxygen-containing groups are removed, preventing the hydrophilic-hydrophobic interface imbalance caused by high oxygen content in GO. Furthermore, the chemical stability of rGO prevents secondary degradation and ensures acid resistance and durability, specifically reflected in the sp... 2 Carbon conjugated structures have high chemical stability and are not corroded by protonated hydrogen in acidic environments; however, the oxygen-containing groups (especially epoxy groups) of GO are prone to ring-opening hydrolysis in acidic environments, leading to the disintegration of their layered structure and thus failing to provide effective protection, and cannot guarantee the stable existence of water-based polyurethane in acidic environments.
[0028] Furthermore, this invention prepares rGO via electrolysis. The rGO generated at the cathode exposes active functional groups (mainly epoxy groups) that can participate in grafting, achieving covalent grafting with alginate (the hydroxyl groups of which react to form stable ether bonds). The alginate surrounds the surface of rGO in a coating form, forming alginate-reduced graphene nanomaterials. As the grafting of alginate and rGO occurs, the conformation of the alginate molecular chain changes. The electron cloud density of the remaining hydroxyl groups increases due to their connection with the oxygen-containing functional groups of rGO (via ether bonds), thus increasing nucleophilic activity. At this point, the hydroxyl groups of alginate attack the active chlorine atoms of sodium sulfonate, significantly accelerating the nucleophilic substitution reaction rate between alginate and sodium sulfonate, resulting in a directional sulfonation reaction. This achieves functional modification of alginate, yielding sulfonated alginate-reduced graphene nanomaterials.
[0029] Finally, the isocyanate groups at the end of the prepolymer have high reactivity and can undergo addition reactions with the active hydrogen groups on the surface of sulfonated alginate-reduced graphene nanomaterials to form stable covalent bonds. Furthermore, sulfonated alginate can form an ion barrier layer, laying the foundation for the acid resistance and mechanical properties of the subsequent water-based polyurethane film.
[0030] Specifically, in S1, electrolysis is selected as the preparation method. In the process of preparing sulfonated alginate-reduced graphene nanomaterials, three reactions can be completed in the same cathode reaction zone: reduction of graphene oxide, alginate grafting of reduced graphene, and modification of alginate with sulfonating agent. This helps to reduce equipment investment and operational complexity, and improve preparation efficiency. Furthermore, the present invention selects a porous titanium mesh coated with graphene oxide as the cathode and a platinum sheet as the anode, and controls the potential of the cathode electrode relative to the saturated calomel electrode within the range of -0.8 to -1.2V.
[0031] Specifically, the porous structure of the porous titanium mesh can support more graphene oxide while allowing the electrolyte in the cathode chamber to fully penetrate to the electrode surface, significantly increasing the contact sites between GO and electrons and the electrolyte substrate. Furthermore, GO is directly coated on the cathode surface, and the electron transfer path is directly from the porous titanium mesh to GO, eliminating the need for GO to diffuse and migrate in the electrolyte and avoiding the problem of insufficient reduction caused by GO agglomeration in the electrolyte. Since the reduction potential of the oxygen-containing groups (epoxy groups, carboxyl groups) on the GO surface is +0.5 to +0.8V (relative to the saturated calomel electrode), and the cathode potential of -0.8 to -1.2V (relative to the saturated calomel electrode) is much lower than this reduction potential, the electron energy can realize the conversion of GO to rGO and avoid the occurrence of hydrogen evolution reaction. Furthermore, this invention controls the cathode chamber to be in an oxygen-free atmosphere, which can block the secondary oxidation of rGO by oxygen generated at the anode and the free radical degradation of alginate. When the mass ratio of GO to sodium alginate is less than 1:3, the alginate does not adequately coat the generated rGO, and rGO is prone to agglomeration and has excessive grafting sites, resulting in a sharp drop in the toughness of the composite material. When the mass ratio of GO to sodium alginate is greater than 1:5, the electrolyte viscosity is too high, and the electrolysis efficiency is reduced.
[0032] In one embodiment, the content of oxygen-containing groups in graphene oxide is 28-40 wt%, and the dispersion concentration of graphene oxide in the cathode chamber electrolyte is 2.0-3.0 mg / mL.
[0033] Specifically, the oxygen-containing group content of graphene oxide can be any value within the range of 28-40 wt%, such as 28 wt%, 30 wt%, 32 wt%, 34 wt%, 36 wt%, 38 wt%, and 40 wt%. If the oxygen-containing group content of graphene oxide is lower than 28 wt%, there are insufficient active sites, resulting in incomplete GO reduction, decreased grafting rate, and the inability of rGO to form an effective reinforcing structure. If the oxygen-containing group content of graphene oxide is higher than 40 wt%, the excessive groups will cause rGO sheets to fragment, lose two-dimensional barrier and reinforcing capabilities, and also exacerbate the hydrogen evolution side reaction, reducing electrolysis efficiency.
[0034] Specifically, the dispersion concentration of graphene oxide in the cathode electrolyte can be any value within the range of 2.0-3.0 mg / mL, such as 2.0 mg / mL, 2.1 mg / mL, 2.2 mg / mL, 2.3 mg / mL, 2.4 mg / mL, 2.5 mg / mL, 2.6 mg / mL, 2.7 mg / mL, 2.8 mg / mL, 2.9 mg / mL, and 3.0 mg / mL. If the dispersion concentration of graphene oxide in the cathode electrolyte is lower than 2.0 mg / mL, insufficient substrate will lead to a decrease in both yield and production efficiency, and large fluctuations in product performance. If the dispersion concentration of graphene oxide in the cathode electrolyte is higher than 3.0 mg / mL, the GO sheets will agglomerate due to van der Waals forces, greatly increasing the electrolyte viscosity and hindering ion migration. This not only prolongs the electrolysis time and exacerbates the hydrogen evolution side reaction, but also causes rGO to form a multi-layered aggregated structure, resulting in a significant decrease in its wear resistance and acid resistance after being composited with polyurethane.
[0035] In one embodiment, in S1, the alginate includes at least one of sodium alginate and potassium alginate, the carboxyl content of the alginate is 10-50 wt%, and the molecular weight of the alginate is 10,000-50,000 Da.
[0036] Specifically, the carboxyl content of alginate can be any value within the range of 10-50 wt%, such as 10 wt%, 15 wt%, 20 wt%, 25 wt%, 30 wt%, 35 wt%, 40 wt%, 45 wt%, or 50 wt%. If the carboxyl content of alginate is less than 10 wt%, there will be insufficient active sites and hydrophilic groups, resulting in poor performance of the prepared sulfonated alginate-reduced graphene nanomaterials and poor compatibility with water-based polyurethanes. If the carboxyl content of alginate is greater than 50 wt%, the excessive hydrophilic groups will lead to a significant increase in the water absorption rate of the polyurethane modified by the sulfonated alginate-reduced graphene nanomaterials, deterioration of water-based resistance, and excessively high electrolyte viscosity will also hinder ion migration.
[0037] Specifically, the molecular weight of alginate can be any value within the range of 10,000-50,000 Da, such as 10,000 Da, 20,000 Da, 30,000 Da, 40,000 Da, or 50,000 Da. If the molecular weight of alginate is lower than 10,000 Da, the molecular chains of alginate are too short to form a complete coating layer, and the reduced graphene is prone to oxidation and aggregation. If the molecular weight of alginate is higher than 50,000 Da, the viscosity of the electrolyte will exceed the process adaptability range, ion migration will be hindered, the electrolysis time will be prolonged, and the excessively long molecular chains are prone to entanglement, resulting in uneven dispersion of sulfonated alginate-reduced graphene nanomaterials. After being combined with water-based polyurethane, stress concentration and a significant decrease in toughness will occur.
[0038] In one embodiment, in S1, the mass ratio of alginate to sulfonating agent is (3-5):(2-4), and the sulfonating agent is sodium 3-chloro-2-hydroxypropanesulfonate.
[0039] Specifically, the quality control of alginate and sulfonating agent is within (3-5):(2-4), and the amount of alginate is slightly higher than that of sulfonating agent. This ensures both the grafting reaction of alginate and reduced graphene and the sufficient use of sulfonating agent to complete the subsequent functional modification.
[0040] In one implementation method, the electrolysis time in S1 is 3-5 hours.
[0041] Specifically, the electrolysis time can be any value within the range of 3-5 hours, such as 3h, 3.5h, 4h, 4.5h, 5h, etc.
[0042] In one implementation method, the electrolysis temperature in S1 is 45-55°C.
[0043] Specifically, the electrolysis temperature can be any point value within the range of 45-55℃, such as 45℃, 46℃, 47℃, 48℃, 49℃, 50℃, 51℃, 52℃, 53℃, 54℃, 55℃, etc.
[0044] In one implementation, in S21, at least one of the following conditions is met:
[0045] (1) The polymer diol includes at least one of the following: bio-based polycaprolactone diol, bio-based polylactic acid diol, polybutylene adipate diol, bio-based polybutylene succinate diol, and polytetrahydrofuran diol.
[0046] (2) The diisocyanate includes at least one of isophorone diisocyanate and hexamethylene diisocyanate;
[0047] (3) The catalyst includes at least one of dibutyltin dilaurate and zinc neodecanoate.
[0048] Specifically, both bio-based polycaprolactone diol (PCL-2000) and bio-based polylactic acid diol (PLA-2000) are biodegradable and can naturally degrade after use. The terminal hydroxyl groups of both undergo urethane addition reactions with the isocyanate groups of diisocyanates to form a water-based polyurethane backbone. The ester bonds in the molecular chain can form hydrogen bonds with the oxygen-containing groups of sulfonated alginate-reduced graphene nanomaterials, enhancing interfacial bonding. Polybutylene adipate diol (PBA-2000) is an aliphatic polyester diol; the presence of aliphatic groups in the backbone is beneficial for improving the acid resistance of water-based polyurethane in acidic environments. The terminal hydroxyl groups undergo addition reactions with isocyanate groups, and the aliphatic ester bonds in the backbone endow the molecular chain with excellent flexibility. The polarity of the ester bonds can form electrostatic interactions with the sulfonic acid groups of sulfonated alginate-reduced graphene nanomaterials. Butyl succinate diol (PBS-2000) is a bio-based polyester diol. Its terminal hydroxyl groups participate in the prepolymerization reaction of water-based polyurethane. The succinate bonds in the main chain are highly polar and can form a multi-hydrogen bond network with the carboxyl groups of sulfonated alginate-reduced graphene nanomaterials. Polytetrahydrofuran diol (PTMG-2000) is an aliphatic polyether diol. Its terminal hydroxyl groups undergo an addition reaction with isocyanate groups. The polyether segments have low crystallinity and good compatibility with sulfonated alginate-reduced graphene nanomaterials, with no interfacial delamination. Isophorone diisocyanate (IPDI) is an alicyclic isocyanate. The isocyanate groups at both ends of the hexamethylene diisocyanate (HDI) molecule undergo a stepwise addition polymerization reaction with the hydroxyl groups of the polymer diol to form a linear aliphatic polyurethane main chain. Moreover, the aliphatic structure has no aromatic rings, which can avoid yellowing caused by long-term ultraviolet radiation.
[0049] In one embodiment, in S22, the concentration of the functional modifier after being prepared into a dispersion is 4-8 mg / mL, and the mass ratio of the functional modifier to the prepolymer is (0.1-1):100.
[0050] Specifically, the concentration of the functional modifier after being formulated into a dispersion can be any value within the range of 4-8 mg / mL, such as 4 mg / mL, 5 mg / mL, 6 mg / mL, 7 mg / mL, or 8 mg / mL. Within this range, the sulfonated alginate-reduced graphene nanomaterials can form a uniform and stable dispersion system in water. This avoids the situation where the concentration is too low (below 4 mg / mL), preventing excessive water dilution of the prepolymer, reducing the prepolymer reaction rate, and decreasing the final emulsion solids content; and also avoids the situation where a concentration above 8 mg / mL leads to excessive viscosity of the sulfonated alginate-reduced graphene nanomaterial system, causing aggregation.
[0051] Specifically, the mass ratio of the functional modifier to the prepolymer can be any value within the range of 0.1:100, 0.2:100, 0.3:100, 0.4:100, 0.5:100, 0.6:100, 0.7:100, 0.8:100, 0.9:100, 1:100, etc. (0.1-1):100). When the mass ratio of the functional modifier to the prepolymer is lower than 0.1:100, the amount of functional modifier is insufficient, and the reinforcement and acid resistance functions are basically ineffective, making it unable to resist the corrosion of acidic lubricants. When the mass ratio of the functional modifier to the prepolymer is higher than 1:100, the excessive sulfonated alginate-reduced graphene nanomaterials are prone to agglomeration, which not only leads to a decrease in the elongation at break of water-based polyurethane, but also makes emulsification of the emulsion difficult.
[0052] In one implementation method, during the in-situ reaction in S22, stirring is required at a speed of 1200-1500 rpm for a duration of 30-60 min.
[0053] Specifically, the stirring speed can be any value within the range of 1200-1500 rpm, such as 1200 rpm, 1300 rpm, 1400 rpm, or 1500 rpm.
[0054] Specifically, the stirring time can be any value within the range of 30-60 minutes, such as 30 min, 35 min, 40 min, 45 min, 50 min, 55 min, or 60 min.
[0055] In one embodiment, in S23, the hydrophilic monomer includes at least one of dimethylolpropionic acid and dimethylolbutyric acid.
[0056] Specifically, the hydrophilic monomers used in this application contain hydrophilic groups, which can effectively improve the hydrophilic properties of polyurethane.
[0057] In one implementation method, the mass ratio of hydrophilic monomer to polymeric diol is (6-10):100.
[0058] Specifically, the mass ratio of hydrophilic monomer to polymeric diol can be any value within the range of 6:100, 7:100, 8:100, 9:100, 10:100, etc. (6-10):100. If the mass ratio of hydrophilic monomer to polymeric diol is lower than 6:100, insufficient hydrophilic groups will lead to prepolymer emulsification failure, emulsion stratification, and insufficient solid content. If the mass ratio of hydrophilic monomer to polymeric diol is higher than 10:100, excessive hydrophilic groups will make the polyurethane film easily swell in acidic environments, which is not conducive to the stable existence of water-based polyurethane in acidic environments.
[0059] In one implementation, in S23, the neutralization treatment involves adding triethylamine to adjust the degree of neutralization to 80%-90%.
[0060] Specifically, the degree of neutralization after neutralization can be any point value within the range of 80%-90%, such as 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, etc.
[0061] In one implementation method, the emulsification process involves adding water for homogenization and emulsification to obtain a water-based polyurethane emulsion.
[0062] The present invention will be further illustrated by the following examples.
[0063] Example 1
[0064] The specific preparation steps of the water-based polyurethane material for the condom of this invention are as follows:
[0065] S1. Preparation of functional modifier: Weigh 0.25g of graphene oxide, 1.0g of sodium alginate, and 0.75g of sodium 3-chloro-2-hydroxypropanesulfonate in a mass ratio of 1:4:3 and disperse them in 100mL of deionized water, so that the dispersion concentration of graphene oxide is 2.5mg / mL, wherein the oxygen-containing group content of graphene oxide is 35wt%, and the molecular weight of sodium alginate is 30000. The sodium alginate contained 30 wt% carboxyl groups. The electrolyte in the anode chamber was a 0.05 mol / L sodium sulfate solution, with a volume of 100 mL. The electrolytes in the cathode and anode chambers were separated by a cation exchange membrane. A porous titanium mesh coated with graphene oxide was selected as the cathode, and a platinum sheet was selected as the anode. The average pore size of the porous titanium mesh was 50 μm. Nitrogen gas was introduced into the cathode chamber at a flow rate of 50 mL / min to maintain an oxygen-free atmosphere. The cathode potential was controlled at -1.0 V (relative to a saturated calomel electrode). Electrolysis was carried out at 45 °C for 4 h to prepare sulfonated alginate-reduced graphene nanomaterials, which are functional modifiers for water-based polyurethane.
[0066] S21. Weigh 50g of bio-based polycaprolactone diol (PCL-2000), 25g of isophorone diisocyanate (IPDI), and 0.1g of dibutyltin dilaurate in a mass ratio of 100:50:0.2, and react at a constant temperature of 80℃ for 2h to prepare a prepolymer.
[0067] S22. Prepare a dispersion of the functional modifier obtained in S1 with a concentration of 6 mg / mL. Add 21 mL of the dispersion to the prepolymer, wherein the mass ratio of the functional modifier to the prepolymer is 0.5:100. Stir at 1350 rpm for 45 min to obtain the composite prepolymer.
[0068] S23. Dimethylolpropionic acid (DMPA) is added to the composite prepolymer for hydrophilic chain extension. The mass ratio of DMPA to PCL-2000 is 8:100. Triethylamine is added to adjust the neutralization degree to 85%. Deionized water is added under high-speed stirring and homogenized for 30 min to prepare a water-based polyurethane emulsion.
[0069] Example 2
[0070] S1. Preparation of functional modifier: Weigh 0.2g of graphene oxide, 0.6g of sodium alginate, and 0.3g of sodium 3-chloro-2-hydroxypropanesulfonate in a mass ratio of 1:3:1.5 and disperse them in 100mL of deionized water, so that the dispersion concentration of graphene oxide is 2.0mg / mL, wherein the oxygen-containing group content of graphene oxide is 28wt%, and the molecular weight of sodium alginate is 10000. The sodium alginate contained 10 wt% carboxyl groups. The electrolyte in the anode chamber was a 0.05 mol / L sodium sulfate solution, with a volume of 100 mL. The electrolytes in the cathode and anode chambers were separated by a cation exchange membrane. A porous titanium mesh coated with graphene oxide was selected as the cathode, and a platinum sheet was selected as the anode. The average pore size of the porous titanium mesh was 50 μm. Nitrogen gas was introduced into the cathode chamber at a flow rate of 50 mL / min to maintain an oxygen-free atmosphere. The cathode potential was controlled at -0.8 V (relative to a saturated calomel electrode). Electrolysis was carried out at 45 °C for 3 h to prepare sulfonated alginate-reduced graphene nanomaterials, which are functional modifiers for water-based polyurethane.
[0071] S21. Weigh 50g of bio-based polycaprolactone diol (PCL-2000), 25g of isophorone diisocyanate (IPDI), and 0.1g of dibutyltin dilaurate in a mass ratio of 100:50:0.2, and react at a constant temperature of 80℃ for 2h to prepare a prepolymer.
[0072] S22. Prepare a dispersion of the functional modifier obtained in S1 with a concentration of 4 mg / mL. Add 16 mL of the dispersion to the prepolymer, wherein the mass ratio of the functional modifier to the prepolymer is 0.1:100. Stir at 1200 rpm for 30 min to obtain the composite prepolymer.
[0073] S23. Dimethylolpropionic acid (DMPA) is added to the composite prepolymer for hydrophilic chain extension, wherein the mass ratio of DMPA to PCL-2000 is 6:100. Triethylamine is added to adjust the neutralization degree to 80%. Deionized water is added under high-speed stirring and homogenized for 30 min to prepare a water-based polyurethane emulsion.
[0074] Example 3
[0075] S1. Preparation of functional modifier: Weigh 0.3g of graphene oxide, 1.5g of sodium alginate, and 1.2g of sodium 3-chloro-2-hydroxypropanesulfonate in a mass ratio of 1:5:4 and disperse them in 100mL of deionized water to achieve a graphene oxide concentration of 3.0mg / mL. The graphene oxide contains 40wt% oxygen-containing groups, and the sodium alginate has a molecular weight of 50,000. The sodium alginate contained 50 wt% carboxyl groups. The electrolyte in the anode chamber was a 0.05 mol / L sodium sulfate solution, with a volume of 100 mL. The electrolytes in the cathode and anode chambers were separated by a cation exchange membrane. A porous titanium mesh coated with graphene oxide was selected as the cathode, and a platinum sheet was selected as the anode. The average pore size of the porous titanium mesh was 50 μm. Nitrogen gas was introduced into the cathode chamber at a flow rate of 50 mL / min to maintain an oxygen-free atmosphere. The cathode potential was controlled at -1.2 V (relative to a saturated calomel electrode). Electrolysis was carried out at 55 °C for 5 h to prepare sulfonated alginate-reduced graphene nanomaterials, which are functional modifiers for water-based polyurethane.
[0076] S21. Weigh 50g of bio-based polycaprolactone diol (PCL-2000), 25g of isophorone diisocyanate (IPDI), and 0.1g of dibutyltin dilaurate in a mass ratio of 100:50:0.2, and react at a constant temperature of 80℃ for 2h to prepare a prepolymer.
[0077] S22. Prepare a dispersion of the functional modifier obtained in S1 with a concentration of 8 mg / mL. Add 78 mL of the dispersion to the prepolymer, wherein the mass ratio of the functional modifier to the prepolymer is 1.0:100. Stir at 1500 rpm for 60 min to obtain the composite prepolymer.
[0078] S23. Dimethylolpropionic acid (DMPA) is added to the composite prepolymer for hydrophilic chain extension. The mass ratio of DMPA to PCL-2000 is 10:100. Triethylamine is added to adjust the neutralization degree to 90%. Deionized water is added under high-speed stirring and homogenized for 30 min to prepare a water-based polyurethane emulsion.
[0079] Example 4
[0080] Most of the steps in this embodiment are the same as those in Embodiment 1, except that in S1, the content of oxygen-containing groups in graphene oxide is 25wt%.
[0081] Example 5
[0082] Most of the steps in this embodiment are the same as those in Embodiment 1, except that the mass ratio of the functional modifier to the prepolymer is 0.05:100.
[0083] Comparative Example 1
[0084] The difference from Example 1 is that no functional modifier is prepared, and water-based polyurethane is prepared directly (i.e., without step S1).
[0085] Comparative Example 2
[0086] The difference from Example 1 is that in S1, nitrogen is not introduced into the cathode chamber, and the atmosphere is oxygen-rich.
[0087] Comparative Example 3
[0088] The difference from Example 1 is that in S1, no cation exchange membrane is provided between the cathode chamber and the anode chamber.
[0089] Performance testing
[0090] The water-based polyurethane emulsions prepared in the above embodiments and comparative examples were used to make polyurethane condoms, and the following tests were conducted. The test methods were as follows: (1) Tensile properties: The tensile strength and elongation at break were tested using a universal testing machine (Shimadzu AG-Xplus) according to GB / T 528-2009; (2) Acid resistance: The film was immersed in a hydrochloric acid solution with pH=2 for 72 hours, and its acid environment (tensile) strength retention rate was tested.
[0091] The method for making polyurethane condoms from the water-based polyurethane prepared in each embodiment and comparative example is as follows: A stainless steel mold is cleaned and dried; the mold is immersed in a water-based polyurethane emulsion; after removal and dripping, it is dried; the treated mold is immersed in a water-based polyurethane emulsion; after removal and dripping, it is dried; a water-based polyurethane film is obtained on the surface of the mold; the open end of the water-based polyurethane film on the mold surface is rolled; the treated mold is immersed in hot water at 50±5℃; after soaking, it is dried; then it is immersed in a release agent; after removal and drying, a dry electrical inspection is performed on the treated film; after passing the electrical inspection, it is demolded to obtain the polyurethane condom.
[0092] The test results are shown in Table 1.
[0093] Table 1
[0094]
[0095] Based on the test data from Examples 1-3 above, it can be seen that the polyurethane condoms prepared in Examples 1-3 exhibit good tensile strength, elongation at break, and acid environment strength retention, meeting the requirements of this invention. Comparing Examples 1 and 4, it can be seen that the graphene oxide used in Example 4 has too low an oxygen-containing group content, lacking reactive sites, resulting in insufficient reduction of the reduced graphene, which in turn leads to a decrease in the tensile strength, elongation at break, and acid environment strength retention of the prepared polyurethane condoms. Comparing Examples 1 and 5, it can be seen that the amount of functional modifier in Example 5 is too small, resulting in insufficient functional modifier, essentially negating the reinforcing and acid-resistant functions, and making it unable to resist the erosion of acidic lubricants, thus leading to a decrease in the tensile strength, elongation at break, and acid environment strength retention of the prepared polyurethane condoms. Comparing Examples 1 and Comparative Example 1, it can be seen that Comparative Example 1, which does not prepare functional modifiers and directly prepares water-based polyurethane (i.e., without step S1), shows significant differences in tensile strength, elongation at break, and acid environment strength retention of the prepared polyurethane condoms compared to Example 1. Comparing Example 1 and Comparative Examples 2-3, it can be seen that in Comparative Example 2, the cathode chamber was not purged with nitrogen and was in an oxygen-rich atmosphere, and in Comparative Example 3, no cation exchange membrane was set between the cathode chamber and the anode chamber. Both of these results in insufficient production of reduced graphene, and the prepared modifier material has poor performance and cannot meet the requirements of this invention.
[0096] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. These modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention, and should all be included within the protection scope of the present invention.
Claims
1. A method for preparing a water-based polyurethane condom, characterized in that, The preparation steps include the following: S1. Preparation of functional modifier: A mixed solution of graphene oxide, alginate, and sulfonic acid is prepared as the cathode electrolyte, and a strong alkali solution of sulfuric acid is prepared as the anode electrolyte. The cathode electrolyte and the anode electrolyte are separated by a cation exchange membrane. A porous titanium mesh coated with graphene oxide is selected as the cathode, and a platinum sheet is selected as the anode. The potential of the cathode electrode relative to the saturated calomel electrode is controlled in the range of -0.8 to -1.2V. Sulfonated alginate-reduced graphene nanomaterials are prepared on the cathode. The sulfonated alginate-reduced graphene nanomaterials are used as functional modifiers in the preparation of water-based polyurethane. The cathode chamber is an oxygen-free atmosphere, and the mass ratio of graphene oxide to sodium alginate in the electrolyte of the cathode chamber is 1:(3-5). S21. A prepolymer is prepared by mixing and reacting polymeric diol, diisocyanate, and catalyst. S22. The functional modifier obtained in S1 is made into a dispersion and added to the prepolymer to carry out an in-situ composite reaction to obtain a composite prepolymer. S23. Add hydrophilic monomers to the composite prepolymer for hydrophilic chain extension, and after neutralization and emulsification treatment, obtain a water-based polyurethane emulsion.
2. The method for preparing water-based polyurethane according to claim 1, characterized in that, In step S1, the content of oxygen-containing groups in the graphene oxide is 28-40 wt%, and the dispersion concentration of the graphene oxide in the electrolyte of the cathode chamber is 2.0-3.0 mg / mL.
3. The method for preparing water-based polyurethane according to claim 1, characterized in that, In S1, the alginate includes at least one of sodium alginate and potassium alginate, the carboxyl content of the alginate is 10-50 wt%, and the molecular weight of the alginate is 10,000-50,000 Da.
4. The method for preparing water-based polyurethane according to claim 1, characterized in that, In S1, the mass ratio of the alginate to the sulfonating agent is (3-5):(2-4), and the sulfonating agent is sodium 3-chloro-2-hydroxypropanesulfonate.
5. The method for preparing water-based polyurethane according to claim 1, characterized in that, In S1, the electrolysis time is 3-5 hours, and / or the electrolysis temperature is 45-55°C.
6. The method for preparing water-based polyurethane according to claim 1, characterized in that, In step S21, at least one of the following conditions is satisfied: (1) The polymer diol includes at least one of bio-based polycaprolactone diol, bio-based polylactic acid diol, polybutylene adipate diol, bio-based polybutylene succinate diol and polytetrahydrofuran diol. (2) The diisocyanate includes at least one of isophorone diisocyanate and hexamethylene diisocyanate; (3) The catalyst includes at least one of dibutyltin dilaurate and zinc neodecanoate.
7. The method for preparing water-based polyurethane according to claim 1, characterized in that, In step S22, the concentration of the functional modifier after being prepared into a dispersion is 4-8 mg / mL, and the mass ratio of the functional modifier to the prepolymer is (0.1-1):
100.
8. The method for preparing water-based polyurethane according to claim 1, characterized in that, In step S22, when carrying out the in-situ reaction, stirring is required. The stirring speed is 1200-1500 rpm and the stirring time is 30-60 min.
9. The method for preparing water-based polyurethane according to claim 1, characterized in that, In S23, the hydrophilic monomer includes at least one of dimethylolpropionic acid and dimethylolbutyric acid, and / or the mass ratio of the hydrophilic monomer to the polymeric diol is (6-10):
100.
10. The method for preparing water-based polyurethane according to claim 1, characterized in that, In step S23, the neutralization treatment involves adding triethylamine to adjust the degree of neutralization to 80%-90%, and / or the emulsification treatment involves adding water for homogenization and emulsification to obtain a water-based polyurethane emulsion.