A low-sensitization latex emulsion, a preparation method thereof and a latex product

Abstract

This application relates to the field of latex processing technology, and discloses a low-allergenic latex solution, its preparation method, and latex products. The preparation method includes the following steps: providing natural latex, subjecting the natural latex to low-temperature centrifugation, collecting the supernatant, filtering, and obtaining a pre-purified latex solution; adding a complex protease and a protein polymerization inhibitor to the pre-purified latex solution, adjusting the pH, and performing isothermal enzymatic hydrolysis to obtain an enzymatically hydrolyzed latex solution; adding a surfactant complex system to the enzymatically hydrolyzed latex solution, stirring evenly, performing intermittent microwave-enhanced treatment, filtering, and obtaining a low-allergenic latex solution. The latex products are prepared from the above-mentioned low-allergenic latex solution through a vulcanization process. The preparation process of this application can efficiently remove soluble proteins from latex, reduce the allergenicity of the latex solution, and the latex products made from the low-allergenic latex solution have high elasticity and high strength properties.

Description

Technical Field

[0001] This invention belongs to the technical field of latex products, and particularly relates to a low-allergenic latex liquid and its preparation method, as well as latex products. Background Technology

[0002] Natural latex is widely used in the production of latex products that come into contact with the human body, such as medical gloves and urinary catheters, due to its excellent mechanical properties and biocompatibility. However, the soluble proteins (such as Hevb1, Hevb3, and Hevb5) contained in natural latex are the core factors that lead to the risk of product sensitization, which limits the scope of application of the products.

[0003] Existing low-allergenic latex treatment processes, such as Chinese patent CN120518798A, disclose a method for reducing the allergenicity of natural latex by multi-enzyme cascade catalysis of rubber proteins. This method uses a multi-enzyme cascade catalysis process of alkaline protease + peptidase to hydrolyze allergenic proteins into amino acids and oligopeptides to reduce allergenicity. However, this method only uses a single enzymatic hydrolysis process and cannot achieve deep removal of soluble proteins.

[0004] Some hypoallergenic latex processing techniques employ surfactant-assisted enzymatic hydrolysis. Commonly used surfactants include SLES and Triton X-100. These surfactants are irritating to the skin: SLES has a skin irritation index of 1.2, classifying it as mild irritation; Triton X-100 is cytotoxic, with a half-maximal cytotoxicity concentration (ICC) of 15 μg / mL, making it difficult to meet the stringent requirements of high-end medical products. Furthermore, the tensile strength and elongation of latex products made from existing hypoallergenic latexes after vulcanization also fail to meet the stringent requirements of high-end medical products.

[0005] Therefore, developing a low-allergenic latex liquid treatment process that deeply removes soluble proteins, stabilizes latex properties, and has excellent surfactant biocompatibility has become a pressing technical challenge for the industry. Summary of the Invention

[0006] The purpose of this invention is to solve at least one problem in the prior art by providing a low-allergenic latex solution, its preparation method, and latex products.

[0007] To achieve the above objectives, this invention proposes a method for preparing a low-allergenic latex solution, comprising the following steps:

[0008] Natural latex is provided, and the natural latex is subjected to low-temperature centrifugation. The supernatant is collected, filtered, and a pre-purified latex solution is obtained. Add a complex protease and a protein polypolymerization inhibitor to the pre-purified latex solution, adjust the pH to 7.2-7.8, and enzymatically hydrolyze for 16-20 hours at 45℃-50℃ to obtain the enzymatically hydrolyzed latex solution. A surfactant complex system was added to the enzymatically hydrolyzed latex solution, stirred evenly, subjected to intermittent microwave intensification treatment, and filtered to obtain a low-allergenic latex solution. The surfactant complex system comprises anionic surfactants of sulfosuccinic acid monoester salts and nonionic surfactants of C12-C18 fatty acid polyglycerol esters in a mass ratio of (1-4):1. The HLB value of the surfactant complex system is 12.5-14.5. The complex protease consists of papain and neutral protease. The intermittent microwave-enhanced treatment uses microwave irradiation. The microwave irradiation process parameters are: power 200W-400W, temperature 60℃-80℃, and total time 3min-8min. The total microwave irradiation time is completed by irradiating for 30s-50s, pausing for 10s-30s, and repeating the cycle. The temperature of the low-temperature centrifugation treatment is... The centrifugation temperature was 2℃-8℃, the rotation speed was 11000rpm-13000rpm, and the centrifugation time was 20min-40min. The supernatant collected after low-temperature centrifugation was filtered through an ultrafiltration membrane to obtain a pre-purified latex solution. The molecular weight cutoff of the ultrafiltration membrane was 80kDa-120kDa, and the membrane pressure during ultrafiltration was 0.2MPa-0.4MPa. The protein polymerization inhibitor was composed of hydroxylamine hydrochloride and sodium metabisulfite, and the amount of protein polymerization inhibitor added was 0.1phr-0.3phr. The amount of complex protease added was 0.08phr-0.12phr. The soluble protein content of the low-sensitization latex solution was ≤4.5μg / g.

[0009] The complex protease in this application can cover more types of hydrolysis sites of sensitizing proteins, hydrolyzing small molecule sensitizing proteins (molecular weight <100kDa) into non-immunogenic small molecule peptides (molecular weight <10kDa). The process parameters in the enzymatic hydrolysis process are optimized through experiments, which can optimize the enzymatic hydrolysis efficiency and make the soluble protein content of the enzymatically hydrolyzed latex solution less than 10μg / g.

[0010] In specific implementation, the process parameters for microwave irradiation can be set as follows: power 200W or 250W or 300W or 400W, temperature 60℃ or 65℃ or 70℃ or 80℃, total time 3min or 4min or 5min or 6min or 8min, with a cycle of 10s pause every 30s irradiation, 20s pause every 30s irradiation, 30s pause every 30s irradiation, 10s pause every 40s irradiation, 20s pause every 40s irradiation, 30s pause every 40s irradiation, 10s pause every 50s irradiation, 20s pause every 50s irradiation, or 30s pause every 50s irradiation, to complete the total microwave irradiation time.

[0011] The thermal conductivity of natural latex is only 0.16 W / (m). Continuous microwave irradiation can cause local temperatures to rise rapidly to over 90°C, forming "hot spots" that cause cross-linking and degradation of rubber hydrocarbon molecular chains, leading to a decline in the mechanical properties of the latex. By adopting the microwave irradiation process parameters of this application, the temperature uniformity of the latex liquid system can be controlled within ±1°C, effectively avoiding thermal degradation of rubber hydrocarbon molecular chains. The high-frequency oscillation of microwaves generated during microwave irradiation can dissociate the hydrogen bonds between proteins and latex particles. When microwave irradiation is paused, the dissociated protein molecules have sufficient time to diffuse into the liquid phase. Using intermittent microwave irradiation of rubber can achieve a microwave energy utilization rate of 72% while reducing production consumption compared to continuous microwave irradiation.

[0012] Microwave irradiation of latex liquid generates a thermal effect that can significantly accelerate molecular motion. Its unique bulk heating method avoids the temperature gradient of conventional heating, enhances the diffusion and penetration rate of surfactants, and the high-frequency oscillation of microwaves can accelerate molecular motion and precisely break the hydrogen bonds at the interface between proteins and latex particles, enhance the protein desorption effect, and desorb the originally tightly bound proteins from the surface of latex particles, effectively improving the protein removal efficiency.

[0013] In practical implementation, the amount of sulfosuccinic acid monoester anionic surfactant added is 0.08%-0.2% of the mass of the enzymatically hydrolyzed latex. Too high or too low an amount of sulfosuccinic acid monoester anionic surfactant may cause foaming, leading to decreased colloidal stability and increased protein residue. The amount of C12-C18 fatty acid polyglycerol ester nonionic surfactant added is 0.05%-0.08% of the mass of the enzymatically hydrolyzed latex. Too high or too low an amount of C12-C18 fatty acid polyglycerol ester nonionic surfactant may lead to decreased film-forming properties of the latex, resulting in uneven cross-linking and affecting mechanical properties.

[0014] In this application, the HLB value of the surfactant complex system is set to 12.5-14.5. This range is close to the HLB value of the target protein in the pre-purified latex solution, indicating a strong affinity between the two, thus resulting in high protein removal efficiency. The role of the protein repolymerization inhibitor is to prevent protein repolymerization in the latex after enzymatic hydrolysis, maintaining the stability of the latex system.

[0015] In practice, the amount of protein polymerization inhibitor added is 0.1 phr, 0.2 phr, or 0.3 phr.

[0016] In specific implementation, the temperature for low-temperature centrifugation can be 2℃, 3℃, 4℃, 5℃, 6℃, or 8℃; the rotation speed can be 11000 rpm, 11500 rpm, 12000 rpm, or 13000 rpm; the centrifugation time can be 20 min, 30 min, or 40 min; the molecular weight cutoff of the ultrafiltration membrane can be 80 kDa, 100 kDa, or 120 kDa; and the membrane pressure during ultrafiltration can be 0.2 MPa, 0.3 MPa, or 0.4 MPa.

[0017] As an optional implementation, the microwave irradiation process parameters are: power 300W, temperature 70℃, and total time 5min, with a 20s pause after every 40s of irradiation, and the total microwave irradiation time is completed in a cycle; the low-temperature centrifugation treatment has a temperature of 4℃, a rotation speed of 12000rpm, and a centrifugation time of 30min.

[0018] As an optional implementation, the amount of the compound protease added is 0.08 phr-0.12 phr. The compound protease is composed of papain and neutral protease in a mass ratio of (1-2):(1-2), and the enzyme activity of papain is ≥800,000 U / g and the enzyme activity of neutral protease is ≥1,000,000 U / g.

[0019] In practice, the mass ratio of papain to neutral protease can be 1:1, 2:1, or 1:2.

[0020] As an optional embodiment, the sulfosuccinate monoester anionic surfactant has an HLB value of 12-14, and the sulfosuccinate monoester anionic surfactant includes at least one of sodium sulfosuccinate monolaurate, disodium cocoyl glucoside sulfosuccinate, and sodium dioctyl sulfosuccinate; the C12-C18 fatty acid polyglycerol ester nonionic surfactant has an HLB value of 13-15, and the C12-C18 fatty acid polyglycerol ester nonionic surfactant includes at least one of polyglycerol-4-laurate, polyglycerol-6-laurate, and polyglycerol-8-laurate.

[0021] The HLB values ​​of C12-C18 fatty acid polyglycerol ester nonionic surfactants were calculated using the Griffin method, and the HLB values ​​of sulfosuccinate monoester anionic surfactants were calculated using the Davies method. The HLB values ​​of disodium cocoyl glucoside sulfosuccinate, sodium dioctyl sulfosuccinate, sodium monolaurate sulfosuccinate, and sodium monolaurate sulfosuccinate were 13.2, 13.5, and 12.8, respectively; the HLB values ​​of polyglycerol-4-laurate, polyglycerol-6-laurate, and polyglycerol-8-laurate were 13.8, 14.0, and 13.0, respectively.

[0022] As an optional implementation, the natural latex has a soluble protein content ≤150μg / g and a dry glue content of 20%-40%.

[0023] The present invention also proposes a low-allergenic latex prepared according to the above-described method for preparing low-allergenic latex, wherein the soluble protein content of the low-allergenic latex is ≤4.5μg / g.

[0024] The present invention also proposes a latex product, which is obtained by vulcanization molding process from the above-mentioned low-allergenic latex liquid, and the latex product has a tensile strength ≥32MPa and an elongation ≥800%.

[0025] As an optional implementation, the latex product is a latex product that comes into contact with the human body, including but not limited to medical gloves, condoms, or urinary catheters.

[0026] As an optional implementation, the specific steps of the vulcanization molding process are as follows: add 0.03%-0.05% of a polyacrylate dispersant to the low-allergenic latex liquid, adjust the dry latex content to 30%-35%, add a vulcanization aid, stir evenly, pre-dry at 60℃-70℃ for 5min-10min, vulcanize at 100℃-130℃ for 10min-20min, and then mold and demold to obtain the latex product; the vulcanization aid is a mixture of sulfur, zinc oxide, and zinc di-n-butyldithiocarbamate.

[0027] The beneficial effects of this invention are: 1. This application employs a triple process of low-temperature centrifugal filtration, biological enzymatic hydrolysis, and chemical microwave enhancement to achieve a synergistic effect, ensuring that the soluble protein content of natural latex is ≤4.5μg / g and the protein removal rate is ≥96.5%, thereby greatly reducing the possibility of allergens from natural latex.

[0028] 2. In the preparation process of this application, a medical-grade composite surfactant of sulfosuccinate and polyglycerol ester is used. On the one hand, the surfactant composite system has low skin irritation, no cytotoxicity requirements, no residue risk, and a biodegradability rate of ≥98%, making it suitable for high-end medical applications. On the other hand, it can effectively remove proteins.

[0029] 3. This application employs a triple process of low-temperature centrifugal filtration + biological enzymatic hydrolysis + chemical microwave enhancement. These three processes work synergistically. Physical pre-purification (low-temperature centrifugal filtration) removes over 60% of large-molecule proteins and impurities, reducing system viscosity and allowing subsequent complex proteases to more fully contact small-molecule allergenic proteins, thus improving enzymatic hydrolysis efficiency. Enzymatic hydrolysis breaks down large-molecule proteins into small-molecule peptides, reducing the binding force between proteins and latex particles, making it easier for subsequent surfactants to penetrate the latex particle surface and improving protein desorption efficiency. Surfactants disrupt the hydrophobic bond between proteins and latex particles through electrostatic interaction, while the high-frequency oscillation of microwaves precisely breaks the hydrogen bonds at the interface between the two. The synergistic effect of these two processes increases protein removal efficiency by 42% compared to using surfactants alone. The triple process synergistically improves the deep protein removal rate.

[0030] 4. The natural structure of the rubber hydrocarbon molecular chain in the low-allergenic latex prepared in this application is intact, which is compatible with conventional vulcanization process. The cross-linking uniformity is high during vulcanization, forming a uniform and dense three-dimensional cross-linking network. The latex products treated by conventional vulcanization process have a tensile strength ≥32MPa and an elongation ≥800%, which makes the products have both high strength and high elasticity.

[0031] The features and advantages of the present invention will be described in detail through embodiments and in conjunction with the accompanying drawings. Attached Figure Description

[0032] Figure 1 This is a flowchart of the low-allergenic latex preparation process of the present invention.

[0033] Figure 2 This is a graph showing the trend of latex protein content changes at each stage in Example 1 of the present invention.

[0034] Figure 3 This diagram illustrates the mechanism of action of intermittent microwave enhancement and surfactant synergistic removal of residual proteins. Detailed Implementation

[0035] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments.

[0036] Example 1 See Figures 1 to 3 This embodiment provides a method for preparing a low-allergenic latex solution, comprising the following steps: S01. Take 10 kg of fresh natural latex with an initial soluble protein content of 120 μg / g and a dry gum content of 24%. Place the fresh natural latex in a low-temperature centrifuge and centrifuge for 30 min at a temperature of 4℃ and a speed of 12000 rpm. Collect 8.5 kg of supernatant. Filter the supernatant through an ultrafiltration membrane with a molecular weight cutoff of 100 kDa at a membrane pressure of 0.3 MPa to obtain 8.0 kg of pre-purified latex solution. S02. Add 1.96g each of papain (enzyme activity 800,000 U / g) and neutral protease (enzyme activity 1,000,000 U / g) to the pre-purified latex solution (equivalent to 0.08 phr of the compound protease, 0.08 phr is equivalent to 10kg × 24% × 0.08% = 0.00192kg = 1.92g, phr is a commonly used unit in the rubber industry, referring to the amount added per 100 parts of dry rubber), 0.15 phr of hydroxylamine hydrochloride and 0.05 phr of sodium metabisulfite, adjust the pH to 7.6, and enzymatically hydrolyze for 18h at a constant temperature of 50℃ to obtain 7.9kg of enzymatically hydrolyzed latex solution; S03. Add 7.9g of disodium cocoyl glucoside sulfosuccinate and 3.2g of polyglycerol-4 laurate to the enzymatically hydrolyzed latex solution, stir well, and place in an industrial microwave device with a frequency of 2400MHz-2500MHz. Microwave irradiation is carried out at a power of 300W, a temperature of 70℃, a total time of 5min, and a cycle of 40s irradiation followed by a 20s pause, repeated 5 times. During the irradiation process, the mixture is continuously stirred at a speed of 60rpm-80rpm. After filtration through a 500-mesh filter, 7.8kg of low-allergenic latex solution is obtained.

[0037] The soluble protein content in the pre-purified latex solution, the enzymatically hydrolyzed latex solution, and the hypoallergenic latex solution obtained in each step of Example 1 was detected using the Lowry method. The specific results were as follows: the soluble protein content in the pre-purified latex solution was 45 μg / g, the soluble protein content in the enzymatically hydrolyzed latex solution was 8.8 μg / g, and the soluble protein content in the hypoallergenic latex solution was 4.5 μg / g. This embodiment also provides a latex product, which is a medical glove. The preparation process is as follows: 0.03% polyacrylate dispersant is added to the low-allergenic latex solution obtained in Example 1, the dry latex content is adjusted to 30%, and vulcanization aids (sulfur 0.8 phr, zinc oxide 0.4 phr, zinc dibutyldithiocarbamate 0.3 phr) are added. The mixture is stirred evenly, and the latex product is obtained by dip molding, pre-drying at 65°C for 6 min, vulcanizing at 105°C for 12 min, and demolding.

[0038] The mechanical properties of the unvulcanized low-sensitivity latex and the vulcanized latex products were measured according to GB / T528-2009 "Determination of tensile stress-strain properties of vulcanized rubber or thermoplastic rubber". The specific measurement results were: tensile strength of 0.9 MPa in the unvulcanized state, tensile strength of 32.1 MPa in the vulcanized state, and elongation of 805%.

[0039] The skin irritation and cytotoxicity of the surfactant system composed of disodium cocoyl glucoside sulfosuccinate and polyglycerol-4 laurate were tested according to the ISO 10993 series standards. The test results were: skin irritation level: 0 (compliant with ISO 10993-10:2021); cytotoxicity test was qualified (compliant with ISO 10993-5:2009).

[0040] Example 2 This embodiment provides a method for preparing a hypoallergenic latex solution, comprising the following steps: S01. Take 10 kg of fresh natural latex with an initial soluble protein content of 140 μg / g and a dry gum content of 24%. Place the fresh natural latex in a low-temperature centrifuge and centrifuge for 30 min at a temperature of 4℃ and a speed of 12000 rpm. Collect 8.4 kg of supernatant. Filter the supernatant through an ultrafiltration membrane with a molecular weight cutoff of 100 kDa at a membrane pressure of 0.3 MPa to obtain 8.1 kg of pre-purified latex solution. S02. Add 1.44g each of papain (enzyme activity 800,000 U / g) and neutral protease (enzyme activity 1,000,000 U / g) to the pre-purified latex solution (equivalent to 0.12 phr of the compound protease, 0.12 phr is equivalent to 10kg × 24% × 0.12% = 0.00288kg = 2.88g, phr is a commonly used unit in the rubber industry, referring to the amount added per 100 parts of dry rubber), 0.15 phr of hydroxylamine hydrochloride and 0.05 phr of sodium metabisulfite, adjust the pH to 7.6, and enzymatically hydrolyze for 18h at a constant temperature of 50℃ to obtain 8.0kg of enzymatically hydrolyzed latex solution; S03. Add 11.2g of disodium cocoyl glucoside sulfosuccinate and 6.4g of polyglycerol-4 laurate to the enzymatically hydrolyzed latex solution, stir well, place in a microwave device, and irradiate at a power of 300W, a temperature of 70℃, a total time of 5min, and repeat 5 times with a 40s irradiation followed by a 20s pause. After filtration through a 500-mesh filter, 7.9kg of low-allergenic latex solution is obtained.

[0041] The soluble protein content in the pre-purified latex solution, the enzymatically hydrolyzed latex solution, and the hypoallergenic latex solution obtained in each step of Example 2 was detected using the Lowry method. The specific results were as follows: the soluble protein content in the pre-purified latex solution was 52 μg / g, the soluble protein content in the enzymatically hydrolyzed latex solution was 8.2 μg / g, and the soluble protein content in the hypoallergenic latex solution was 4.0 μg / g. This embodiment also provides a latex product, which is a urinary catheter. The preparation process is as follows: 0.05% polyacrylate dispersant is added to the low-allergenic latex solution obtained in Example 2, the dry latex content is adjusted to 32%, and vulcanization aids (sulfur 0.7 phr, zinc oxide 0.5 phr, zinc dibutyldithiocarbamate 0.4 phr) are added. The mixture is stirred evenly, molded, pre-dried at 65°C for 8 min, vulcanized at 108°C for 10 min, and the latex product is obtained after demolding.

[0042] The mechanical properties of the unvulcanized low-sensitivity latex liquid and the vulcanized latex products of Example 2 were measured according to GB / T528-2009 "Determination of tensile stress-strain properties of vulcanized rubber or thermoplastic rubber". The specific measurement results were: tensile strength of 1.2 MPa in the unvulcanized state, tensile strength of 34.2 MPa in the vulcanized state, and elongation of 850%.

[0043] The skin irritation and cytotoxicity of the surfactant system composed of disodium cocoyl glucoside sulfosuccinate and polyglycerol-4 laurate in Example 2 were tested according to the ISO 10993 series standards. The test results were: skin irritation level: 0 (compliant with ISO 10993-10:2021); cytotoxicity test qualified (compliant with ISO 10993-5:2009).

[0044] Example 3 This embodiment provides a method for preparing a hypoallergenic latex solution, comprising the following steps: S01. Take 10 kg of fresh natural latex with an initial soluble protein content of 130 μg / g and a dry gum content of 24%. Place the fresh natural latex in a low-temperature centrifuge and centrifuge for 30 min at a temperature of 4℃ and a speed of 12000 rpm. Collect 8.4 kg of supernatant. Filter the supernatant through an ultrafiltration membrane with a molecular weight cutoff of 100 kDa at a membrane pressure of 0.3 MPa to obtain 8.15 kg of pre-purified latex solution. S02. Add 1.2g each of papain (enzyme activity 800,000 U / g) and neutral protease (enzyme activity 1,000,000 U / g) to the pre-purified latex solution (equivalent to 0.10 phr of the compound protease, 0.10 phr is equivalent to 10kg × 24% × 0.10% = 0.0024kg = 2.4g, phr is a commonly used unit in the rubber industry, referring to the amount added per 100 parts of dry rubber), 0.15 phr of hydroxylamine hydrochloride and 0.05 phr of sodium metabisulfite, adjust the pH to 7.6, and enzymatically hydrolyze for 18h at a constant temperature of 50℃ to obtain 8.05kg of enzymatically hydrolyzed latex solution; S03. Add a surfactant complex system (HLB value of 13.2) composed of 9.66g disodium cocoyl glucoside sulfosuccinate and 4.8g polyglycerol-4 laurate to the enzymatically hydrolyzed latex solution. Stir well and place in an industrial microwave device with a frequency of 2450MHz. Irradiate at a power of 300W, a temperature of 70℃, a total time of 5min, and repeat 5 times with a 40s irradiation followed by a 20s pause. Stir continuously at 60rpm during irradiation. After filtration through a 500-mesh filter, obtain 7.95kg of low-allergenic latex solution.

[0045] The soluble protein content in the pre-purified latex solution, the enzymatically hydrolyzed latex solution, and the hypoallergenic latex solution obtained in each step of Example 3 was detected using the Lowry method. The specific results were as follows: the soluble protein content in the pre-purified latex solution was 48 μg / g, the soluble protein content in the enzymatically hydrolyzed latex solution was 8.5 μg / g, and the soluble protein content in the hypoallergenic latex solution was 4.2 μg / g.

[0046] This embodiment also provides a latex product, which is a condom. The preparation process is as follows: 0.04% polyacrylate dispersant is added to the low-allergenic latex solution obtained in Example 3, the dry latex content is adjusted to 31%, and vulcanization aids (sulfur 0.8 phr, zinc oxide 0.4 phr, zinc dibutyldithiocarbamate 0.3 phr) are added. The mixture is stirred evenly, and the latex product is obtained by dip molding, pre-drying at 65°C for 7 min, vulcanizing at 105°C for 13 min, and demolding.

[0047] The mechanical properties of the unvulcanized low-sensitivity latex liquid and the vulcanized latex product of Example 3 were measured according to GB / T528-2009 "Determination of tensile stress-strain properties of vulcanized rubber or thermoplastic rubber". The specific measurement results were: tensile strength of 1.0 MPa in the unvulcanized state, tensile strength of 33.5 MPa in the vulcanized state, and elongation of 830%.

[0048] The skin irritation and cytotoxicity of the surfactant system composed of disodium cocoyl glucoside sulfosuccinate and polyglycerol-4 laurate in Example 3 were tested according to the ISO 10993 series standards. The test results were: skin irritation level: 0 (compliant with ISO 10993-10:2021); cytotoxicity test qualified (compliant with ISO 10993-5:2009).

[0049] Example 4 This embodiment provides a method for preparing a low-allergenic latex liquid. Except for step S01, where the low-temperature centrifugation temperature is 6°C, the rotation speed is 11000 rpm, and the centrifugation time is 20 min, the molecular weight cutoff of the ultrafiltration membrane during supernatant filtration is 80 kDa, and the membrane pressure during ultrafiltration is 0.2 MPa, the remaining steps are the same as in Example 3.

[0050] The soluble protein content in the pre-purified latex solution was found to be 54.3 μg / g, while the soluble protein content in the low-allergenic latex solution was 4.4 μg / g. Using this pre-purified latex solution, vulcanized latex products were obtained through the latex product preparation process described in Example 3. The vulcanized products showed a tensile strength of 33.0 MPa and an elongation of 820%.

[0051] Example 5 This embodiment provides a method for preparing a low-allergenic latex solution. Except for step S01, where the dry latex content of the fresh natural latex is 28%, the low-temperature centrifugation treatment temperature is 2°C, the rotation speed is 13000 rpm, the centrifugation time is 40 min, the molecular weight cutoff of the ultrafiltration membrane during supernatant filtration is 120 kDa, and the membrane pressure during ultrafiltration is 0.4 MPa, the remaining steps are the same as in Example 3.

[0052] The soluble protein content in the pre-purified latex solution was found to be 46.2 μg / g, while the soluble protein content in the low-allergenic latex solution was 4.1 μg / g. Using this pre-purified latex solution, vulcanized latex products were obtained through the latex product preparation process described in Example 3. The vulcanized products showed a tensile strength of 33.8 MPa and an elongation of 835%.

[0053] Example 6 This embodiment provides a method for preparing a low-allergenic latex solution. Except for step S02, where the papain enzyme activity is 1 million U / g, the neutral protease enzyme activity is 1.2 million U / g, the amount of hydroxylamine hydrochloride added is 0.2 phr, the amount of sodium metabisulfite added is 0.1 phr, the pH is adjusted to 7.8, and the enzymatic hydrolysis reaction is carried out at a constant temperature of 46°C for 16 hours to obtain the enzymatically hydrolyzed latex solution, the remaining steps are the same as in Example 3.

[0054] Example 7 This embodiment provides a method for preparing a low-allergenic latex solution. Except that in step SO2, the amount of hydroxylamine hydrochloride added is 0.06 phr, the amount of sodium metabisulfite added is 0.02 phr, the pH is adjusted to 7.2, and the enzymatic hydrolysis reaction is carried out at a constant temperature of 45°C for 20 h to obtain the enzymatically hydrolyzed latex solution, the remaining steps are the same as in Example 3.

[0055] Example 8 This embodiment provides a method for preparing a low-allergenic latex liquid. Except that in step S03, disodium cocoyl glucoside sulfosuccinate is replaced with sodium dioctyl sulfosuccinate, and polyglycerol-4-laurate is replaced with polyglycerol-4-laurate, the remaining steps are the same as in Example 3.

[0056] The soluble protein content in the low-allergenic latex solution was found to be 4.3 μg / g. Using this pre-purified latex solution, vulcanized latex products were obtained through the latex product preparation process described in Example 3. The vulcanized products showed a tensile strength of 33.82 MPa, an elongation of 825%, and a skin irritation level of 0 with the surface active system, exhibiting no cytotoxicity.

[0057] Example 9 This embodiment provides a method for preparing a low-allergenic latex liquid. Except for step S03, which involves microwave irradiation at a power of 200W, a temperature of 60℃, a total time of 8min, and a cycle of 8 times with a 50s irradiation followed by a 10s pause, the remaining steps are the same as in embodiment 3.

[0058] Example 10 This embodiment provides a method for preparing a low-allergenic latex solution. Except for step S03, where microwave irradiation is performed at a power of 400W, a temperature of 70℃, a total time of 5 minutes, and repeated 5 times with a 30-second pause after each irradiation, the remaining steps are the same as in Example 3. The soluble protein content in the final latex solution was measured to be 4.5 μg / g.

[0059] Example 11 This embodiment provides a method for preparing a low-allergenic latex solution. Except for step S03, where microwave irradiation is performed at a power of 300W, a temperature of 80℃, a total time of 5 minutes, and repeated 5 times with a 30-second pause after each irradiation, the remaining steps are the same as in Example 3. The soluble protein content in the final latex solution was measured to be 4.0 μg / g.

[0060] Example 12 This embodiment provides a method for preparing a low-allergenic latex solution. Except for step S03, where microwave irradiation is performed at a power of 300W, a temperature of 80℃, a total time of 5 minutes, and repeated 5 times with a 30-second pause after each irradiation, the remaining steps are the same as in Example 3. The soluble protein content in the final latex solution was measured to be 4.0 μg / g.

[0061] Example 13 This embodiment provides a method for preparing a low-allergenic latex solution. Except for step S03, where microwave irradiation is performed at a power of 200W, a temperature of 70℃, a total time of 5 minutes, and repeated 5 times with a 30-second pause after each irradiation, the remaining steps are the same as in Example 3. The soluble protein content in the final latex solution was measured to be 4.4 μg / g.

[0062] Example 14 This embodiment provides a method for preparing a low-allergenic latex solution. Except for step S03, where microwave irradiation is performed at a power of 200W, a temperature of 70℃, a total time of 3 minutes, and repeated three times with a 30-second pause after each irradiation, the remaining steps are the same as in Example 3. The soluble protein content in the final latex solution was measured to be 4.5 μg / g.

[0063] Example 15 This embodiment provides a method for preparing a low-allergenic latex solution. Except for step S03, in which 4.83g each of disodium cocoyl glucoside sulfosuccinate and sodium monolaurate sulfosuccinate, and 2.4g each of polyglycerol-4-laurate and polyglycerol-8-laurate are added to the enzymatically hydrolyzed latex solution, the remaining steps are the same as in Example 3.

[0064] Example 16 This embodiment provides a method for preparing a low-allergenic latex solution. Except for step S03, in which 5.64g of disodium cocoyl glucoside sulfosuccinate, 3.36g of sodium monolaurate sulfosuccinate, 2.4g of polyglycerol-4-laurate, and 2.6g of polyglycerol-8-laurate are added to the enzymatically hydrolyzed latex solution, the remaining steps are the same as in Example 3.

[0065] Comparative Example 1 The preparation method of the latex solution in this comparative example is the same as in Example 3, except that in step S03, the microwave irradiation is performed at a power of 300W, a temperature of 70℃, a total time of 5 minutes, and the irradiation is repeated 5 times with a 20-second pause. The soluble protein content in the final latex solution was measured to be 8.2 μg / g.

[0066] Comparative Example 2 The preparation method of the latex solution in this comparative example is the same as in Example 3, except that in step S03, microwave irradiation is performed at a power of 300W, a temperature of 70℃, a total time of 5 minutes, and the irradiation is repeated every 65 seconds with a 5-second pause. The soluble protein content in the final latex solution was measured to be 7.5 μg / g.

[0067] Comparative Example 3 The preparation method of the latex solution in this comparative example is the same as in Example 3, except that in step S03, a 70°C water bath treatment is used instead of microwave irradiation. The final latex solution was found to contain 5.3 μg / g of soluble protein.

[0068] Comparative Example 4 The preparation method of this comparative latex solution uses only the S01 step of Example 3 to obtain the latex solution.

[0069] Comparative Example 5 The preparation method of this comparative latex solution only uses steps S01 and S02 of Example 3 to obtain the latex solution.

[0070] Comparative Example 6 The preparation method of the latex solution in this comparative example is the same as in Example 3, except that in step S03, an equal mass of the existing surfactant sodium dodecylbenzenesulfonate is added to the enzymatically hydrolyzed latex solution. The soluble protein content of the final latex solution was measured to be 6.8 μg / g.

[0071] I. Testing of soluble protein content in latex solutions prepared by different processes and performance of vulcanized latex products Equal amounts of latex solutions obtained using the preparation methods of Example 3, Comparative Example 4, and Comparative Example 5 were taken, and latex products were obtained by treating each latex solution according to the vulcanization process of Example 3. During the testing process, the soluble protein content in the latex solution and the tensile strength and elongation of the latex products were tested according to the Lowry method and the test standard GB / T528-2009 "Determination of Tensile Stress-Strain Properties of Vulcanized Rubber or Thermoplastic Rubber". The specific test results are shown in Table 1 below.

[0072] Table 1. Soluble protein content and performance test results of latex products in different latex solutions.

[0073] As shown in Table 1, compared with the single centrifugal filtration treatment of Comparative Example 4 and the centrifugal filtration treatment + biological enzymatic hydrolysis treatment of Comparative Example 5, the latex solution treated by centrifugal filtration treatment + biological enzymatic hydrolysis treatment + chemical microwave enhancement treatment in this application has a higher removal rate of soluble protein and the latex product after vulcanization has better performance.

[0074] II. Tests on the effects of different amounts of compound protease added on the soluble protein content of latex solutions and the properties of vulcanized latex products. The same natural latex was divided into four groups. The four groups of natural latex were prepared into latex solution and latex products according to the preparation method of Example 3. Except for the different amount of complex protease added to the pre-purified latex solution in step S02 (the specific settings are as shown in Table 2 below), the parameters of the other steps were the same. The final protein content and soluble protein content of the latex solution were tested, and the specific test results are shown in Table 2 below.

[0075] Table 2. Performance test results of latex solutions and latex products under different amounts of compound protease.

[0076] As shown in Table 2, the amount of compound protease added has a certain impact on the final soluble protein removal rate of the latex solution. If the amount of compound protease added is too high, the final soluble protein content of the latex solution will be higher than 4.5 μg / g, and the tensile strength and elongation of the latex products prepared after vulcanization will be relatively worse.

[0077] The above embodiments are illustrative of the present invention and are not intended to limit the present invention. Any simple modifications to the present invention are within the scope of protection of the present invention.

Claims

1. A method for preparing a low-allergenic latex solution, characterized in that: It includes the following steps: Natural latex is provided, and the natural latex is subjected to low-temperature centrifugation. The supernatant is collected, filtered, and a pre-purified latex solution is obtained. Add a complex protease and a protein polypolymerization inhibitor to the pre-purified latex solution, adjust the pH to 7.2-7.8, and enzymatically hydrolyze for 16-20 hours at 45℃-50℃ to obtain the enzymatically hydrolyzed latex solution. A surfactant complex system was added to the enzymatically hydrolyzed latex solution, stirred evenly, subjected to intermittent microwave intensification treatment, and filtered to obtain a low-allergenic latex solution. The surfactant complex system comprises anionic surfactants of sulfosuccinic acid monoester salts and nonionic surfactants of C12-C18 fatty acid polyglycerol esters in a mass ratio of (1-4):

1. The HLB value of the surfactant complex system is 12.5-14.

5. The complex protease consists of papain and neutral protease. The intermittent microwave-enhanced treatment uses microwave irradiation. The microwave irradiation process parameters are: power 200W-400W, temperature 60℃-80℃, and total time 3min-8min. The total microwave irradiation time is completed by irradiating for 30s-50s, pausing for 10s-30s, and repeating the cycle. The temperature of the low-temperature centrifugation treatment is... The centrifugation temperature was 2℃-8℃, the rotation speed was 11000rpm-13000rpm, and the centrifugation time was 20min-40min. The supernatant collected after low-temperature centrifugation was filtered through an ultrafiltration membrane to obtain a pre-purified latex solution. The molecular weight cutoff of the ultrafiltration membrane was 80kDa-120kDa, and the membrane pressure during ultrafiltration was 0.2MPa-0.4MPa. The protein polymerization inhibitor was composed of hydroxylamine hydrochloride and sodium metabisulfite, and the amount of protein polymerization inhibitor added was 0.1phr-0.3phr. The amount of complex protease added was 0.08phr-0.12phr. The soluble protein content of the low-sensitization latex solution was ≤4.5μg / g.

2. The method for preparing the low-allergenic latex liquid according to claim 1, characterized in that: The microwave irradiation process parameters are: power 300W, temperature 70℃, and total time 5min, with a 20s pause after every 40s of irradiation, and the total microwave irradiation time is completed in a cycle; the low-temperature centrifugation treatment has a temperature of 4℃, a rotation speed of 12000rpm, and a centrifugation time of 30min.

3. The method for preparing the low-allergenic latex liquid as described in claim 1, characterized in that: The complex protease is composed of papain and neutral protease in a mass ratio of (1-2):(1-2), with the papain having an enzyme activity ≥800,000 U / g and the neutral protease having an enzyme activity ≥1,000,000 U / g.

4. The method for preparing the low-allergenic latex liquid as described in claim 1, characterized in that: The sulfosuccinic acid monoester salt anionic surfactant has an HLB value of 12-14.

5. The method for preparing the low-allergenic latex liquid as described in claim 1, characterized in that: The sulfosuccinate monoester anionic surfactant includes at least one of sodium monolaurate sulfosuccinate, disodium cocoyl glucoside sulfosuccinate, and sodium dioctyl sulfosuccinate.

6. The method for preparing the low-allergenic latex liquid as described in claim 5, characterized in that: The C12-C18 fatty acid polyglycerol ester nonionic surfactant has an HLB value of 13-15, and the C12-C18 fatty acid polyglycerol ester nonionic surfactant includes at least one of polyglycerol-4-laurate, polyglycerol-6-laurate, and polyglycerol-8-laurate.

7. The method for preparing the low-allergenic latex liquid according to claim 1, characterized in that: The natural latex has a soluble protein content of ≤150μg / g and a dry glue content of 20%-40%.

8. A low-allergenic latex prepared by the method of preparing a low-allergenic latex according to any one of claims 1 to 7.

9. A latex product, characterized in that: The latex product is obtained by vulcanization molding process from the low-allergenic latex liquid of claim 8, and the tensile strength of the latex product is ≥32MPa and the elongation is ≥800%.

10. The latex product as described in claim 9, characterized in that: The specific steps of the vulcanization molding process are as follows: add 0.03%-0.05% of polyacrylate dispersant to the low-allergenic latex liquid, adjust the dry latex content to 30%-35%, add vulcanization aid, stir evenly, pre-dry at 60℃-70℃ for 5min-10min, vulcanize at 100℃-130℃ for 10min-20min, and then mold and demold to obtain the latex product; the vulcanization aid is a mixture of sulfur, zinc oxide, and zinc di-n-butyldithiocarbamate.

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