Herbal microcapsule-containing breathable polyurethane foam and preparation process thereof

Abstract

The invention relates to the technical field of polyurethane foams, and particularly discloses a breathable polyurethane foam containing herbal microcapsules and a preparation process thereof.Herbal essential oil / SiO2-polyurea / polyurethane double-layer microcapsules are synthesized, a flexible polyurethane outer layer is good in compatibility with a polyurethane foam matrix, good toughness of a polyurethane foam material can be kept, and the breathable polyurethane foam containing the herbal microcapsules is good in breathability and good in breathability. The SiO2-polyurea wall materials of the inner layer are combined through chemical bonds, so that the mechanical property and compactness of the microcapsule are improved, and the effect of slowly releasing the herbal essential oil is achieved; a quaternary ammonium salt group and a rigid benzene ring structure of lignin are combined to a polyurethane network, so that the polyurethane foam material has antibacterial property, good strength and compression set resistance.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of polyurethane foam, in particular to a breathable polyurethane foam containing herbal microcapsules and a preparation process thereof. BACKGROUND

[0002] Polyurethane foam is a kind of high polymer produced by chemical reaction of polyol and isocyanate as main raw materials under the action of catalyst, surfactant, foaming agent and other additives, and foaming by gas. Due to its three-dimensional porous network physical structure, it has the characteristics of low density, good flexibility, good cushioning performance and strong plasticity, and is widely used in the home textile industry. It is the core filling material for preparing sofa, pillow, cushion and mattress products.

[0003] Although polyurethane foam materials are widely used in the home textile industry, traditional polyurethane foam materials still have defects, which affect the experience of polyurethane foam products to users, such as breathability. During the foaming process of polyurethane foam, the opening rate of the cells is low or there are defects such as incomplete foaming, which leads to insufficient breathability of the polyurethane foam and affects the experience of the user; during the production process of polyurethane foam, the incomplete foaming, residual isocyanate monomer or amine catalyst volatilizes during use, which affects the product quality and brings discomfort to the user; under the background of consumption upgrading, the functions of home textile products are gradually diversified, and the traditional polyurethane foam material only provides the functions of filling and supporting, which is relatively single. Manufacturers want to add herbal essential oil to give polyurethane foam the functions of antibacterial and anti-mite, and to help sleep and relax. However, directly adding herbal essential oil to the polyurethane foam formula will interfere with the normal synthesis of polyurethane foam, leading to foaming failure. In a small number of successful products, the herbal essential oil will also volatilize rapidly in the finished product stage, and cannot achieve long-lasting effect. Therefore, it is particularly important to develop a kind of polyurethane foam material with good breathability, safety and environmental protection, long-term stable carrying of herbal components, and realization of functions such as antibacterial and anti-mite, and help sleep and relax, to promote the further application of polyurethane foam in the home textile industry. SUMMARY

[0004] The purpose of the present application is to provide a kind of polyurethane foam containing herbal microcapsules and a preparation process thereof, which can release herbal essential oil components for a long time, has good antibacterial property and good breathability, and solves the problems of single function of traditional polyurethane foam, poor breathability of foam material and easy deformation of foam structure.

[0005] In order to solve the above technical problems, the present application provides the following technical scheme: A preparation process of a breathable polyurethane foam containing herbal microcapsules, specifically comprising: Step 1: Mix castor oil polyol and isophorone diisocyanate to prepare bio-based PU prepolymer; Step 2: Using herbal essential oil, amino-modified nano-silica, isophorone diisocyanate, ethylenediamine and bio-based PU prepolymer as raw materials, herbal essential oil / SiO2-polyurea / polyurethane double-layer microcapsules are prepared; Step 3: The bio-based PU prepolymer is modified by using amino-terminated PEG-1000 and N-methyldiethanolamine to obtain a quaternary ammonium salt-modified PU prepolymer; Step 4: Polymeric MDI is added to the lignin-based polyol to prepare a lignin-MDI prepolymer; Step 5: Castor oil polyol is mixed with the quaternary ammonium salt-modified PU prepolymer to form a polyurethane foam A component, the lignin-MDI prepolymer is mixed with polymeric MDI to form a polyurethane foam B component, the polyurethane foam A component is mixed with the polyurethane foam B component, and foaming and curing are performed to obtain a breathable polyurethane foam containing herbal microcapsules.

[0006] As a limitation of the present application, the preparation method of the bio-based PU prepolymer is as follows: The castor oil polyol is dried at 100-120°C for 1-2h and cooled, isophorone diisocyanate is added to the castor oil polyol under nitrogen protection, and the reaction is carried out at 70-80°C with stirring at 300-400rpm for 3-4h. When the -NCO content in the system is 5-7wt%, the reaction is stopped, and the system is cooled to room temperature to obtain a bio-based PU prepolymer; The mass ratio of isophorone diisocyanate to castor oil polyol is (25-30):(100-120).

[0007] Under nitrogen protection, the hydroxyl groups of the castor oil polyol react with the isocyanate groups of isophorone diisocyanate to form a prepolymer containing urethane bonds. Isophorone diisocyanate has a risk of volatilization in the synthesis of polyurethane foam. After the synthesis of the prepolymer, the molecular weight increases and the volatility decreases sharply. At the same time, the isocyanate groups of the prepolymer are affected by steric hindrance and polarity, and their reactivity is more moderate than that of isophorone diisocyanate. This avoids defects such as uneven cell structure caused by excessive reaction rate, improves product yield, and helps to form a more uniform and delicate open-cell structure, thereby improving the air permeability and resilience of the polyurethane foam material. The prepolymer forms a cross-linked network as a flexible cross-linking segment, and its long-chain structure helps to disperse and consume stress, thereby improving the toughness, tear resistance and resilience of the polyurethane foam material.

[0008] As a limitation of the present application, the preparation method of the herbal essential oil / SiO2-polyurea / polyurethane double-layer microcapsule is as follows: The bio-based PU prepolymer is added into acetone, stirred at 300-400 rpm for 20-30 min to obtain a bio-based PU prepolymer acetone dispersion, the herbal essential oil / SiO2-polyurea microcapsule is added into deionized water, stirred at 300-400 rpm for 20-30 min, the bio-based PU prepolymer acetone dispersion is added, stirred at 300-400 rpm at 25-30°C for 1-2 h, 1,4-butanediol is added dropwise, and the reaction is carried out at 300-400 rpm at 50-60°C for 3-4 h, after the reaction is completed, the mixture is cooled, filtered, washed with deionized water, and vacuum dried at 30-40°C for 8-10 h to obtain the herbal essential oil / SiO2-polyurea / polyurethane double-layer microcapsule. The mass ratio of the bio-based PU prepolymer, the herbal essential oil / SiO2-polyurea microcapsule and 1,4-butanediol is (15-20):(20-30):(2-3).

[0009] As a limitation of the present application, the preparation method of the herbal essential oil / SiO2-polyurea microcapsule is as follows: The nanosilica is added into a mixed solution of anhydrous ethanol and deionized water, stirred at 200-300 rpm for 20-30 min, ultrasonically dispersed for 20-30 min, the pH is adjusted to 10-11, the silane coupling agent KH-550 is added, and the reaction is carried out at 300-400 rpm at 70-80°C for 6-8 h, after the reaction is completed, the mixture is cooled, filtered, washed with anhydrous ethanol and deionized water, and vacuum dried at 70-80°C for 4-6 h to obtain the aminated nanosilica. The aminated nanosilica and the emulsifier are added into deionized water, stirred at 200-300 rpm for 20-30 min, ultrasonically dispersed for 20-30 min to obtain an aminated nanosilica dispersed aqueous phase, the isophorone diisocyanate is added into the herbal essential oil, stirred at 200-300 rpm for 20-30 min to obtain an herbal essential oil oil phase, the herbal essential oil oil phase is added dropwise into the aminated nanosilica dispersed aqueous phase under high-speed shearing at 10000-12000 rpm at 25-30°C, and the high-speed shearing is maintained for 8-10 min to obtain a microcapsule prepolymer emulsion, the ethylenediamine is added dropwise into the microcapsule prepolymer emulsion at 400-500 rpm at 35-45°C, the reaction is carried out at 400-500 rpm at 35-45°C for 3-4 h, after the reaction is completed, the mixture is cooled, filtered, washed with deionized water, and vacuum dried at 30-40°C for 8-10 h to obtain the herbal essential oil / SiO2-polyurea microcapsule.

[0010] As a limitation of the present application, the mass ratio of the nanosilica and silane coupling agent KH-550 is (10-20):(1.5-2.5); the mass ratio of the aminated nanosilica, emulsifier, isophorone diisocyanate and herbal essential oil is (10-20):(5-7):(15-17):(100-120).

[0011] The herbal essential oil / SiO2-polyurea / polyurethane double-layer microcapsule is a double-layer wall material structure microcapsule with herbal essential oil as the core material, SiO2-polyurea as the inner layer wall material and polyurethane as the outer layer wall material. In the inner layer wall material, the nanosilica is modified by the silane coupling agent KH-550 to change the hydrophilic nanosilica into hydrophobic particles with a surface rich in amino groups. The modified nanosilica reacts with the isocyanate groups through the amino groups to form a SiO2-polyurea wall material with good compatibility and binding, forming a herbal essential oil / SiO2-polyurea microcapsule. The nanosilica participates in the formation of the polyurea crosslinking network through the amino groups, fills the voids of the polyurea crosslinking network and enhances the strength of the polyurea crosslinking network, thereby improving the mechanical properties and compactness of the microcapsule and achieving the effect of slow release of the herbal essential oil.

[0012] The outer layer wall material of the double-layer microcapsule is polyurethane, and the bio-based PU prepolymer is an oil-soluble monomer that does not dissolve in water but is adsorbed onto the outer surface of the inner layer wall material (SiO2-polyurea wall material) under the action of mechanical stirring. The isocyanate groups on the molecular chain of the PU prepolymer preferentially react with the residual amino groups of the SiO2-polyurea wall material to form urea bonds, and part of the isocyanate groups react with the residual hydroxyl groups on the wall material to form urethane bonds. The PU prepolymer is fixed to the SiO2-polyurea wall material through chemical bonds. The 1,4-butanediol added later can effectively diffuse to the interface between the PU prepolymer and water and preferentially react with the PU prepolymer. Although a small amount of isocyanate groups of the PU prepolymer reacts with water to form a loose polyurea interface during the process, the reaction rate of the isocyanate groups with the polyols is much faster than that with water under heating conditions. A polyurethane outer layer is formed on the outside of the SiO2-polyurea wall material. The flexible polyurethane outer layer has good compatibility with the polyurethane foam matrix, which helps the polyurethane foam material maintain good toughness. The polyurethane outer layer is chemically bonded to the SiO2-polyurea wall material, achieving the fixation of the microcapsule, reducing the peeling of the microcapsule interface and preventing the microcapsule from falling off during use. At the same time, the polyurethane outer layer can further delay the release rate of the herbal essential oil and improve the long-acting slow release performance of the herbal essential oil.

[0013] As a limitation of the present application, the preparation method of the quaternary ammonium salt modified PU prepolymer is: The bio-based PU prepolymer is added into acetone, stirred at 300-400 rpm for 20-30 min, N-methyldiethanolamine is added, stirred at 40-50 DEG C and 300-400 rpm for 2-3 h, bromoethane is added dropwise, stirred at 25-30 DEG C and 300-400 rpm for 16-20 h, after the reaction is completed, the solvent is removed by rotary evaporation, the product is dissolved in tetrahydrofuran, then precipitated in ethyl ether, filtered, and dried at 30-40 DEG C under vacuum for 10-12 h to obtain the quaternary ammonium salt modified PU prepolymer; The mass ratio of the bio-based PU prepolymer, N-methyldiethanolamine and bromoethane is (20-25):(3-5):(5-6).

[0014] The bio-based PU prepolymer is modified by N-methyldiethanolamine, the isocyanate groups at the ends of the bio-based PU prepolymer react with the hydroxyl groups of N-methyldiethanolamine to form urethane bonds, and then the nucleophilic substitution reaction of bromoethane with the tertiary amine groups occurs to generate quaternary ammonium salt groups, which are combined to the polyurethane molecular chain and become part of the polyurethane crosslinking network, so that the long-acting antibacterial function is realized, and the functional failure or safety problems caused by the migration or dissolution of small molecule antibacterial agents are avoided.

[0015] As a limitation of the application, the preparation method of the lignin-MDI prepolymer is as follows: The alkaline lignin is added into glycerol, stirred at 300-400 rpm for 20-30 min, concentrated phosphoric acid is added under nitrogen protection, and stirring is continued for 10-15 min, and the reaction is carried out at 80-90 DEG C and 300-400 rpm for 3-4 h, after the reaction is completed, the system is cooled to 50-60 DEG C, then neutralized by adding potassium carbonate, dissolved in dichloromethane, separated by water washing, dried with anhydrous magnesium sulfate, filtered, and dichloromethane is removed by rotary evaporation, then polyethylene glycol is added to obtain a lignin-based polyol, the lignin-based polyol is dried at 100-120 DEG C for 1-2 h, then polymeric MDI is added dropwise under nitrogen protection, and the reaction is carried out at 80-90 DEG C and 300-400 rpm for 1-2 h, the content of -NCO in the system is detected to be 15-17 wt%, the reaction is stopped, and the system is cooled to room temperature to obtain the lignin-MDI prepolymer; The mass ratio of the alkaline lignin, glycerol, concentrated phosphoric acid and polyethylene glycol is (60-70):(100-120):(5-7):(20-30); the mass ratio of the lignin-based polyol and polymeric MDI is (20-25):(80-90).

[0016] Under the conditions of concentrated phosphoric acid and heating, lignin is depolymerized, and esterification or etherification reaction occurs between the hydroxyl groups of glycerol and the phenolic hydroxyl groups or alcoholic hydroxyl groups of the depolymerized lignin, the flexible glycerol segments are grafted onto the aromatic ring structure of lignin to form lignin-based polyols, the hydroxyl groups on the lignin-based polyols further react with the isocyanate groups on the polymeric MDI to generate urethane bonds, and a lignin-MDI prepolymer is formed, the rigid benzene ring structure of lignin is uniformly dispersed in the polyurethane network, and the strength, compression permanent deformation resistance, air permeability and flame retardant performance of the polyurethane foam are enhanced.

[0017] As a limitation of the present application, the preparation method of the air-permeable polyurethane foam containing herbal microcapsules is: The silicone surfactant, amine catalyst, organic bismuth catalyst and deionized water are added into the castor oil polyol, stirred at 300-400 rpm for 20-30 min, the quaternary ammonium salt modified PU prepolymer is added, stirred at 200-300 rpm for 10-15 min, then the herbal essential oil / SiO2-polyurea / polyurethane double-layer microcapsules are added, stirred at 100-150 rpm for 5-10 min to obtain the polyurethane foam A component, the lignin-MDI prepolymer is mixed with the polymeric MDI, stirred at 300-400 rpm for 20-30 min to obtain the polyurethane foam B component, the polyurethane foam A component and the polyurethane foam B component are mixed to form a polyurethane foaming slurry, which is injected into a mold, foamed and cured at 50-60℃ for 1-2 h, cured at 70-80℃ for 1-2 h, demolded to obtain the air-permeable polyurethane foam containing herbal microcapsules.

[0018] As a limitation of the present application, by mass fraction, the polyurethane foam A component includes: 1-2 parts of silicone surfactant, 0.2-0.3 parts of amine catalyst, 0.1-0.2 parts of organic bismuth catalyst, 4-6 parts of deionized water, 60-70 parts of castor oil polyol, 15-20 parts of quaternary ammonium salt modified PU prepolymer and 5-10 parts of herbal essential oil / SiO2-polyurea / polyurethane double-layer microcapsules; By mass fraction, the polyurethane foam B component includes: 35-40 parts of lignin-MDI prepolymer and 45-50 parts of polymeric MDI.

[0019] An air-permeable polyurethane foam containing herbal microcapsules is prepared according to the preparation process described in any one of the above.

[0020] Compared with the prior art, the present application has the following advantages: This invention synthesizes a bilayer microcapsule of herbal essential oil / SiO2-polyurea / polyurethane. The flexible polyurethane outer layer has good compatibility with the polyurethane foam matrix, which helps the polyurethane foam material maintain good toughness. The SiO2-polyurea wall material of the inner layer is chemically bonded to each other, which improves the mechanical properties and density of the microcapsule and achieves the effect of slow release of herbal essential oil. The bio-based PU prepolymer is modified with N-methyldiethanolamine and bromoethane, which binds quaternary ammonium salt groups to the polyurethane molecular chain and becomes part of the polyurethane cross-linking network. This achieves the functions of not easily falling off and failing, and long-lasting antibacterial effect, avoiding functional failure or safety issues caused by the migration or dissolution of small molecule antibacterial agents. The polymerized MDI is modified with lignin polyol to synthesize lignin-MDI prepolymer. The rigid benzene ring structure of lignin is uniformly dispersed in the polyurethane network, which enhances the strength, compression set resistance, resilience and flame retardant properties of the polyurethane foam material. Detailed Implementation

[0021] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. The terminology used in the embodiments is for describing specific implementation schemes, not for limiting the scope of protection of the present invention. The dosages in the embodiments are laboratory-scale tests and can be scaled up proportionally. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0022] Nano-silica (particle size: 30nm), emulsifier (brand name: Span-80), herbal essential oil (lavender essential oil, density: 0.9g / mL), castor oil polyol (hydroxyl value: 180mg KOH / g), polyethylene glycol (Mn=400), alkaline lignin (pH=10), polymeric MDI (NCO content: 32wt%), organosilicon surfactant (brand name: Tegostab B 4900), amine catalyst (brand name: A-33), organobismuth catalyst (brand name: BiCAT-8108).

[0023] The preparation method of herbal essential oil / SiO2-polyurea microcapsules is as follows: 10g of nano-silica was added to a mixed solution of 200mL anhydrous ethanol and 50mL deionized water, stirred at 200rpm for 20min, ultrasonically dispersed for 20min, the pH was adjusted to 10, 1.5g of silane coupling agent KH-550 was added, and the reaction was carried out at 70℃ and 400rpm for 8h. After the reaction was completed, the mixture was cooled, filtered, washed with anhydrous ethanol and deionized water, and vacuum dried at 80℃ for 4h to obtain aminated nano-silica. 10g of aminated nano-silica and 5g of emulsifier were added to 500mL of deionized water, stirred at 200rpm for 20min, and ultrasonically dispersed for 20min to obtain an aqueous phase of aminated nano-silica dispersion. 15g of isophorone diisocyanate was added to 100g of herbal essential oil, stirred at 200rpm for 20min to obtain an oil phase of herbal essential oil. The oil phase of herbal essential oil was dropped into the aqueous phase of aminated nano-silica dispersion at 30℃ and 10000rpm high-speed shearing, and sheared at 10000rpm for 10min to obtain a microcapsule prepolymer emulsion. 6g of ethylenediamine was added to the microcapsule prepolymer emulsion at 40℃ and 400rpm, and the reaction was carried out at 40℃ and 400rpm for 4h. After the reaction was completed, the mixture was cooled, filtered, washed with deionized water, and vacuum dried at 40℃ for 8h to obtain herbal essential oil / SiO2-polyurea microcapsules.

[0024] Example 1: A preparation process for a breathable polyurethane foam containing herbal microcapsules, specifically as follows: Step 1: Dry the castor oil polyol at 120℃ for 1 hour and cool it. Under nitrogen protection, add 25g of isoflurane diisocyanate to 100g of castor oil polyol and stir at 80℃ and 400rpm for 3 hours. When the -NCO content in the system is 5wt%, stop the reaction and cool to room temperature to obtain the bio-based PU prepolymer. Step 2: Add 15g of bio-based PU prepolymer to 100mL of acetone and stir at 400rpm for 20min to obtain a bio-based PU prepolymer acetone dispersion. Add 20g of herbal essential oil / SiO2-polyurea microcapsules to 500mL of deionized water and stir at 400rpm for 20min. Add the bio-based PU prepolymer acetone dispersion and stir at 30℃ and 400rpm for 1h. Add 2g of 1,4-butanediol dropwise and stir at 60℃ and 400rpm for 3h. After the reaction is complete, cool, filter, wash with deionized water, and vacuum dry at 40℃ for 8h to obtain herbal essential oil / SiO2-polyurea / polyurethane bilayer microcapsules. Step 3: Add 20g of bio-based PU prepolymer to 100mL of acetone and stir at 400rpm for 20min. Add 3g of N-methyldiethanolamine and react at 40℃ and 400rpm for 3h. Add 5g of bromoethane dropwise and react at 30℃ and 400rpm for 20h. After the reaction is complete, remove the solvent by rotary evaporation. Dissolve the product in tetrahydrofuran and precipitate it in ice-cold diethyl ether. Filter and vacuum dry at 30-40℃ for 10-12h to obtain quaternary ammonium salt modified PU prepolymer. Step 4: Add 60g of alkaline lignin to 100g of glycerol and stir at 400rpm for 20min. Under nitrogen protection, add 5g of 85wt% concentrated phosphoric acid and continue stirring for 10min. React at 85℃ and 400rpm for 4h. After the reaction is complete, cool to 60℃, add potassium carbonate to neutralize the system, and then dissolve in dichloromethane. Wash with water and separate the liquid. Dry the organic phase with anhydrous magnesium sulfate and filter. Rotary evaporate the dichloromethane and add 20g of polyethylene glycol to obtain lignin-based polyol. Dry 20g of lignin-based polyol at 120℃ for 1h and then cool. Under nitrogen protection, add 80g of polymeric MDI dropwise and react at 80℃ and 400rpm for 2h. The -NCO content in the system is detected to be 15wt%. Stop the reaction and cool to room temperature to obtain lignin-MDI prepolymer. Step 5: Add 1g of organosilicon surfactant, 0.2g of amine catalyst, 0.1g of organobismuth catalyst, and 4g of deionized water to 60g of castor oil polyol, stir at 400rpm for 20min, add 15g of quaternary ammonium salt modified PU prepolymer, stir at 300rpm for 10min, then add 5g of herbal essential oil / SiO2-polyurea / polyurethane bilayer microcapsules, stir at 150rpm for 10min to obtain polyurethane foam component A. Mix 35g of lignin-MDI prepolymer with 45g of polymeric MDI, stir at 300rpm for 20min to obtain polyurethane foam component B. Mix polyurethane foam component A and polyurethane foam component B to form polyurethane foam slurry and inject it into a mold. Foam and cure at 50℃ for 2h, then cure at 70℃ for 2h, demold to obtain breathable polyurethane foam containing herbal microcapsules.

[0025] Example 2: A preparation process for a breathable polyurethane foam containing herbal microcapsules, specifically as follows: Step 1: Dry the castor oil polyol at 120℃ for 1 hour and cool it. Under nitrogen protection, add 27g of isoflurane diisocyanate to 110g of castor oil polyol and stir at 80℃ and 400rpm for 3 hours. When the -NCO content in the system is 5wt%, stop the reaction and cool to room temperature to obtain the bio-based PU prepolymer. Step 2: Add 17g of bio-based PU prepolymer to 100mL of acetone and stir at 400rpm for 20min to obtain a bio-based PU prepolymer acetone dispersion. Add 25g of herbal essential oil / SiO2-polyurea microcapsules to 500mL of deionized water and stir at 400rpm for 20min. Add the bio-based PU prepolymer acetone dispersion and stir at 30℃ and 400rpm for 1h. Add 2.5g of 1,4-butanediol dropwise and stir at 60℃ and 400rpm for 3h. After the reaction is complete, cool, filter, wash with deionized water, and vacuum dry at 40℃ for 8h to obtain herbal essential oil / SiO2-polyurea / polyurethane bilayer microcapsules. Step 3: Add 23g of bio-based PU prepolymer to 100mL of acetone and stir at 400rpm for 20min. Add 4g of N-methyldiethanolamine and react at 40℃ and 400rpm for 3h. Add 5.5g of bromoethane dropwise and react at 30℃ and 400rpm for 20h. After the reaction is complete, remove the solvent by rotary evaporation. Dissolve the product in tetrahydrofuran and precipitate it in ice-cold diethyl ether. Filter and vacuum dry at 30-40℃ for 10-12h to obtain the quaternary ammonium salt modified PU prepolymer. Step 4: Add 65g of basic lignin to 110g of glycerol and stir at 400rpm for 20min. Under nitrogen protection, add 6g of 85wt% concentrated phosphoric acid and continue stirring for 10min. React at 85℃ and 400rpm for 4h. After the reaction is complete, cool to 60℃, add potassium carbonate to neutralize the system, and then dissolve in dichloromethane. Wash with water and separate the liquid. Dry the organic phase with anhydrous magnesium sulfate and filter. Rotary evaporate the dichloromethane and add 25g of polyethylene glycol to obtain lignin-based polyol. Dry 23g of lignin-based polyol at 120℃ for 1h and then cool. Under nitrogen protection, add 85g of polymeric MDI dropwise and react at 80℃ and 400rpm for 2h. The -NCO content in the system is detected to be 15wt%. Stop the reaction and cool to room temperature to obtain lignin-MDI prepolymer. Step 5: Add 1.5g of organosilicon surfactant, 0.25g of amine catalyst, 0.2g of organobismuth catalyst, and 5g of deionized water to 65g of castor oil polyol, stir at 400rpm for 20min, add 17g of quaternary ammonium salt modified PU prepolymer, stir at 300rpm for 10min, then add 7g of herbal essential oil / SiO2-polyurea / polyurethane bilayer microcapsules, stir at 150rpm for 10min to obtain polyurethane foam component A. Mix 37g of lignin-MDI prepolymer with 47g of polymeric MDI, stir at 300rpm for 20min to obtain polyurethane foam component B. Mix polyurethane foam component A and polyurethane foam component B to form polyurethane foam slurry and inject it into a mold. Foam and cure at 50℃ for 2h, then cure at 70℃ for 2h, demold to obtain breathable polyurethane foam containing herbal microcapsules.

[0026] Example 3: A preparation process for a breathable polyurethane foam containing herbal microcapsules, specifically as follows: Step 1: Dry the castor oil polyol at 120℃ for 1 hour and cool it. Under nitrogen protection, add 30g of isoflurane diisocyanate to 120g of castor oil polyol and stir at 80℃ and 400rpm for 3 hours. When the -NCO content in the system is 5wt%, stop the reaction and cool to room temperature to obtain the bio-based PU prepolymer. Step 2: Add 20g of bio-based PU prepolymer to 100mL of acetone and stir at 400rpm for 20min to obtain a bio-based PU prepolymer acetone dispersion. Add 30g of herbal essential oil / SiO2-polyurea microcapsules to 500mL of deionized water and stir at 400rpm for 20min. Add the bio-based PU prepolymer acetone dispersion and stir at 30℃ and 400rpm for 1h. Add 3g of 1,4-butanediol dropwise and stir at 60℃ and 400rpm for 3h. After the reaction is complete, cool, filter, wash with deionized water, and vacuum dry at 40℃ for 8h to obtain herbal essential oil / SiO2-polyurea / polyurethane bilayer microcapsules. Step 3: Add 25g of bio-based PU prepolymer to 100mL of acetone and stir at 400rpm for 20min. Add 5g of N-methyldiethanolamine and react at 40℃ and 400rpm for 3h. Add 6g of bromoethane dropwise and react at 30℃ and 400rpm for 20h. After the reaction is complete, remove the solvent by rotary evaporation. Dissolve the product in tetrahydrofuran and precipitate it in ice-cold diethyl ether. Filter and vacuum dry at 30-40℃ for 10-12h to obtain the quaternary ammonium salt modified PU prepolymer. Step 4: Add 70g of alkaline lignin to 120g of glycerol and stir at 400rpm for 20min. Under nitrogen protection, add 7g of 85wt% concentrated phosphoric acid and continue stirring for 10min. React at 85℃ and 400rpm for 4h. After the reaction is complete, cool to 60℃, add potassium carbonate to neutralize the system, and then dissolve in dichloromethane. Wash with water and separate the liquid. Dry the organic phase with anhydrous magnesium sulfate and filter. Rotary evaporate the dichloromethane and add 30g of polyethylene glycol to obtain lignin-based polyol. Dry 25g of lignin-based polyol at 120℃ for 1h and then cool. Under nitrogen protection, add 90g of polymeric MDI dropwise and react at 80℃ and 400rpm for 2h. The -NCO content in the system is detected to be 15wt%. Stop the reaction and cool to room temperature to obtain lignin-MDI prepolymer. Step 5: Add 2g of organosilicon surfactant, 0.3g of amine catalyst, 0.2g of organobismuth catalyst, and 6g of deionized water to 70g of castor oil polyol, stir at 400rpm for 20min, add 30g of quaternary ammonium salt modified PU prepolymer, stir at 300rpm for 10min, then add 10g of herbal essential oil / SiO2-polyurea / polyurethane bilayer microcapsules, stir at 150rpm for 10min to obtain polyurethane foam component A. Mix 40g of lignin-MDI prepolymer with 50g of polymeric MDI, stir at 300rpm for 20min to obtain polyurethane foam component B. Mix polyurethane foam component A and polyurethane foam component B to form polyurethane foam slurry and inject it into a mold. Foam and cure at 50℃ for 2h, then cure at 70℃ for 2h, demold to obtain breathable polyurethane foam containing herbal microcapsules.

[0027] Based on Example 1, the following comparative experiments were conducted, specifically Comparative Example 1, Comparative Example 2, and Comparative Example 3, as described below: Comparative Example 1: This comparative example relates to a preparation process of a breathable polyurethane foam containing herbal microcapsules. The difference from Example 1 is that herbal essential oil / SiO2-polyurea microcapsules are added to component A of the polyurethane foam. Specifically: Step 1: Dry the castor oil polyol at 120℃ for 1 hour and cool it. Under nitrogen protection, add 25g of isoflurane diisocyanate to 100g of castor oil polyol and stir at 80℃ and 400rpm for 3 hours. When the -NCO content in the system is 5wt%, stop the reaction and cool to room temperature to obtain the bio-based PU prepolymer. Step 2: Add 20g of bio-based PU prepolymer to 100mL of acetone and stir at 400rpm for 20min. Add 3g of N-methyldiethanolamine and react at 40℃ and 400rpm for 3h. Add 5g of bromoethane dropwise and react at 30℃ and 400rpm for 20h. After the reaction is complete, remove the solvent by rotary evaporation. Dissolve the product in tetrahydrofuran and precipitate it in ice-cold diethyl ether. Filter and vacuum dry at 30-40℃ for 10-12h to obtain quaternary ammonium salt modified PU prepolymer. Step 3: Add 60g of alkaline lignin to 100g of glycerol and stir at 400rpm for 20min. Under nitrogen protection, add 5g of 85wt% concentrated phosphoric acid and continue stirring for 10min. React at 85℃ and 400rpm for 4h. After the reaction is complete, cool to 60℃, add potassium carbonate to neutralize the system, and then dissolve in dichloromethane. Wash with water and separate the liquid. Dry the organic phase with anhydrous magnesium sulfate and filter. Rotary evaporate the dichloromethane and add 20g of polyethylene glycol to obtain lignin-based polyol. Dry 20g of lignin-based polyol at 120℃ for 1h and then cool. Under nitrogen protection, add 80g of polymeric MDI dropwise and react at 80℃ and 400rpm for 2h. The -NCO content in the system is detected to be 15wt%. Stop the reaction and cool to room temperature to obtain lignin-MDI prepolymer. Step 4: Add 1g of organosilicon surfactant, 0.2g of amine catalyst, 0.1g of organobismuth catalyst, and 4g of deionized water to 60g of castor oil polyol, stir at 400rpm for 20min, add 15g of quaternary ammonium salt modified PU prepolymer, stir at 300rpm for 10min, add 5g of herbal essential oil / SiO2-polyurea microcapsules, stir at 150rpm for 10min to obtain polyurethane foam component A. Mix 35g of lignin-MDI prepolymer with 45g of polymeric MDI, stir at 300rpm for 20min to obtain polyurethane foam component B. Mix polyurethane foam component A and polyurethane foam component B to form polyurethane foam slurry and inject it into a mold. Foam and cure at 50℃ for 2h, cure at 70℃ for 2h, demold to obtain breathable polyurethane foam containing herbal microcapsules.

[0028] Comparative Example 2: This comparative example relates to a preparation process of a breathable polyurethane foam containing herbal microcapsules. The difference from Example 1 is that no quaternary ammonium salt modified PU prepolymer was added. Specifically: Step 1: Dry the castor oil polyol at 120℃ for 1 hour and cool it. Under nitrogen protection, add 25g of isoflurane diisocyanate to 100g of castor oil polyol and stir at 80℃ and 400rpm for 3 hours. When the -NCO content in the system is 5wt%, stop the reaction and cool to room temperature to obtain the bio-based PU prepolymer. Step 2: Add 15g of bio-based PU prepolymer to 100mL of acetone and stir at 400rpm for 20min to obtain a bio-based PU prepolymer acetone dispersion. Add 20g of herbal essential oil / SiO2-polyurea microcapsules to 500mL of deionized water and stir at 400rpm for 20min. Add the bio-based PU prepolymer acetone dispersion and stir at 30℃ and 400rpm for 1h. Add 2g of 1,4-butanediol dropwise and stir at 60℃ and 400rpm for 3h. After the reaction is complete, cool, filter, wash with deionized water, and vacuum dry at 40℃ for 8h to obtain herbal essential oil / SiO2-polyurea / polyurethane bilayer microcapsules. Step 3: Add 60g of alkaline lignin to 100g of glycerol and stir at 400rpm for 20min. Under nitrogen protection, add 5g of 85wt% concentrated phosphoric acid and continue stirring for 10min. React at 85℃ and 400rpm for 4h. After the reaction is complete, cool to 60℃, add potassium carbonate to neutralize the system, and then dissolve in dichloromethane. Wash with water and separate the liquid. Dry the organic phase with anhydrous magnesium sulfate and filter. Rotary evaporate the dichloromethane and add 20g of polyethylene glycol to obtain lignin-based polyol. Dry 20g of lignin-based polyol at 120℃ for 1h and then cool. Under nitrogen protection, add 80g of polymeric MDI dropwise and react at 80℃ and 400rpm for 2h. The -NCO content in the system is detected to be 15wt%. Stop the reaction and cool to room temperature to obtain lignin-MDI prepolymer. Step 4: Add 1g of organosilicon surfactant, 0.2g of amine catalyst, 0.1g of organobismuth catalyst, and 4g of deionized water to 60g of castor oil polyol, stir at 400rpm for 20min, add 5g of herbal essential oil / SiO2-polyurea / polyurethane bilayer microcapsules, stir at 150rpm for 10min to obtain polyurethane foam component A. Mix 35g of lignin-MDI prepolymer with 45g of polymeric MDI, stir at 300rpm for 20min to obtain polyurethane foam component B. Mix polyurethane foam component A and polyurethane foam component B to form polyurethane foam slurry and inject it into a mold. Foam and cure at 50℃ for 2h, then cure at 70℃ for 2h. Demold to obtain breathable polyurethane foam containing herbal microcapsules.

[0029] Comparative Example 3: This comparative example relates to a preparation process of a breathable polyurethane foam containing herbal microcapsules. The difference from Example 1 is that lignin-MDI prepolymer was not added. Specifically: Step 1: Dry the castor oil polyol at 120℃ for 1 hour and cool it. Under nitrogen protection, add 25g of isoflurane diisocyanate to 100g of castor oil polyol and stir at 80℃ and 400rpm for 3 hours. When the -NCO content in the system is 5wt%, stop the reaction and cool to room temperature to obtain the bio-based PU prepolymer. Step 2: Add 15g of bio-based PU prepolymer to 100mL of acetone and stir at 400rpm for 20min to obtain a bio-based PU prepolymer acetone dispersion. Add 20g of herbal essential oil / SiO2-polyurea microcapsules to 500mL of deionized water and stir at 400rpm for 20min. Add the bio-based PU prepolymer acetone dispersion and stir at 30℃ and 400rpm for 1h. Add 2g of 1,4-butanediol dropwise and stir at 60℃ and 400rpm for 3h. After the reaction is complete, cool, filter, wash with deionized water, and vacuum dry at 40℃ for 8h to obtain herbal essential oil / SiO2-polyurea / polyurethane bilayer microcapsules. Step 3: Add 20g of bio-based PU prepolymer to 100mL of acetone and stir at 400rpm for 20min. Add 3g of N-methyldiethanolamine and react at 40℃ and 400rpm for 3h. Add 5g of bromoethane dropwise and react at 30℃ and 400rpm for 20h. After the reaction is complete, remove the solvent by rotary evaporation. Dissolve the product in tetrahydrofuran and precipitate it in ice-cold diethyl ether. Filter and vacuum dry at 30-40℃ for 10-12h to obtain quaternary ammonium salt modified PU prepolymer. Step 4: Add 1g of organosilicon surfactant, 0.2g of amine catalyst, 0.1g of organobismuth catalyst, and 4g of deionized water to 60g of castor oil polyol, stir at 400rpm for 20min, add 15g of quaternary ammonium salt modified PU prepolymer, stir at 300rpm for 10min, then add 5g of herbal essential oil / SiO2-polyurea / polyurethane bilayer microcapsules, stir at 150rpm for 10min to obtain polyurethane foam component A. Mix polyurethane foam component A with 45g of polymeric MDI to form polyurethane foam slurry and inject it into a mold. Foam and cure at 50℃ for 2h, then cure at 70℃ for 2h, demold to obtain breathable polyurethane foam containing herbal microcapsules.

[0030] Testing experiment: According to the preparation methods of each embodiment and comparative example, breathable polyurethane foam containing herbal microcapsules was prepared as a sample, and air permeability test, compression set resistance test, sustained release performance test of herbal essential oil and antibacterial test were carried out.

[0031] Air permeability test: The test is conducted in accordance with the "Determination of Air Flow Rate of Porous Elastic Polymer Materials" (GB / T10655-2003). The test conditions are a pressure difference of 150 Pa. The test measures the air flow rate through the sample. Each type of polyurethane foam is tested 3 times, and the average value is taken.

[0032] Compression set test: The test is conducted in accordance with the "Determination of Compression Set of Porous Polymer Elastic Materials" (GB / T 10653-2001). The test conditions are: compressed to 50% of the original thickness and held at 70℃ for 22 hours. The compression set rate of the sample is calculated. Each type of polyurethane foam is tested 3 times and the average value is taken.

[0033] The sustained-release performance test of herbal essential oils: After weighing a 20mm×20mm×10mm sample, it was kept at 60℃ for 7 days. After 7 days, it was taken out, cooled to room temperature, and weighed again. Then it was placed in a Soxhlet extractor and the remaining herbal essential oil was continuously extracted with n-hexane. After removing the solvent by rotary evaporation, it was weighed again and the release rate of herbal essential oils was calculated.

[0034] Antimicrobial test: The test was conducted in accordance with the "Evaluation of Antimicrobial Properties of Textiles Part 3: Oscillation Method" (GB / T20944.3-2008). The test species were Staphylococcus aureus and Escherichia coli, and the antimicrobial rate of the test sample was measured.

[0035]

[0036] Conclusion: The test data shows that, compared with the comparative example, the breathable polyurethane foam containing herbal microcapsules prepared in this embodiment has higher air permeability, herbal essential oil release rate and antibacterial rate under the same test conditions, while its compression set is lower. The breathable polyurethane foam containing herbal microcapsules provided by this invention has good air permeability, compression set resistance, slow release and antibacterial properties.

[0037] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from the spirit or essential characteristics of the invention. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, it is intended that all variations falling within the meaning and scope of equivalents of the claims be included within the present invention.

Claims

1. A preparation process for a breathable polyurethane foam containing herbal microcapsules, characterized in that: Specifically: Step 1: Mix castor oil polyol with isophorone diisocyanate to prepare bio-based PU prepolymer; Step 2: Using herbal essential oil, aminated nano-silica, isophorone diisocyanate, ethylenediamine and bio-based PU prepolymer as raw materials, prepare herbal essential oil / SiO2-polyurea / polyurethane bilayer microcapsules; Step 3: Modify the bio-based PU prepolymer with terminal amino PEG-1000 and N-methyldiethanolamine to obtain quaternary ammonium salt modified PU prepolymer; Step 4: Add polymerized MDI to lignin-based polyol to prepare lignin-MDI prepolymer; Step 5: Mix castor oil polyol with quaternary ammonium salt modified PU prepolymer to form polyurethane foam component A. Mix lignin-MDI prepolymer with polymeric MDI to form polyurethane foam component B. Mix polyurethane foam component A and polyurethane foam component B, foam and cure to obtain breathable polyurethane foam containing herbal microcapsules.

2. The preparation process of a breathable polyurethane foam containing herbal microcapsules according to claim 1, characterized in that: The preparation method of bio-based PU prepolymer is as follows: Castor oil polyol was dried at 100-120℃ for 1-2 hours and then cooled. Under nitrogen protection, isoflurane diisocyanate was added to castor oil polyol and stirred at 70-80℃ and 300-400 rpm for 3-4 hours. When the -NCO content in the system was 5-7wt%, the reaction was stopped and the mixture was cooled to room temperature to obtain the bio-based PU prepolymer. The mass ratio of isophorone diisocyanate to castor oil polyol is (25-30):(100-120).

3. The preparation process of a breathable polyurethane foam containing herbal microcapsules according to claim 1, characterized in that: The preparation method of herbal essential oil / SiO2-polyurea / polyurethane bilayer microcapsules is as follows: Bio-based PU prepolymer was added to acetone and stirred at 300-400 rpm for 20-30 min to obtain a bio-based PU prepolymer acetone dispersion. Herbal essential oil / SiO2-polyurea microcapsules were added to deionized water and stirred at 300-400 rpm for 20-30 min. The bio-based PU prepolymer acetone dispersion was added, and the mixture was stirred at 25-30℃ and 300-400 rpm for 1-2 h. 1,4-Butanediol was added dropwise, and the mixture was stirred at 50-60℃ and 300-400 rpm for 3-4 h. After the reaction was completed, the mixture was cooled, filtered, washed with deionized water, and vacuum dried at 30-40℃ for 8-10 h to obtain herbal essential oil / SiO2-polyurea / polyurethane bilayer microcapsules. The mass ratio of bio-based PU prepolymer, herbal essential oil / SiO2-polyurea microcapsules and 1,4-butanediol is (15-20):(20-30):(2-3).

4. The preparation process of a breathable polyurethane foam containing herbal microcapsules according to claim 3, characterized in that: The preparation method of herbal essential oil / SiO2-polyurea microcapsules is as follows: Nano-silica was added to a mixed solution of anhydrous ethanol and deionized water, stirred at 200-300 rpm for 20-30 min, ultrasonically dispersed for 20-30 min, and the pH was adjusted to 10-11. Silane coupling agent KH-550 was added, and the reaction was carried out at 70-80℃ and stirred at 300-400 rpm for 6-8 h. After the reaction was completed, the mixture was cooled, filtered, washed with anhydrous ethanol and deionized water, and vacuum dried at 70-80℃ for 4-6 h to obtain aminated nano-silica. Aminated nano-silica and emulsifier were added to deionized water and stirred at 200-300 rpm for 20-30 min, followed by ultrasonic dispersion for 20-30 min to obtain an aqueous phase of aminated nano-silica. Isophorone diisocyanate was added to the herbal essential oil and stirred at 200-300 rpm for 20-30 min to obtain the oil phase of the herbal essential oil. The oil phase of the herbal essential oil was then dripped into the aminated nano-silica at 25-30℃ and 10000-12000 rpm. Microcapsule prepolymer emulsion was obtained by high-speed shearing at 10,000-12,000 rpm for 8-10 min in a silica-dispersed aqueous phase. Ethylenediamine was then added dropwise to the microcapsule prepolymer emulsion at 35-45℃ and 400-500 rpm. The reaction was carried out at 35-45℃ and 400-500 rpm for 3-4 h. After the reaction was completed, the mixture was cooled, filtered, washed with deionized water, and vacuum dried at 30-40℃ for 8-10 h to obtain herbal essential oil / SiO2-polyurea microcapsules.

5. The preparation process of a breathable polyurethane foam containing herbal microcapsules according to claim 4, characterized in that: The mass ratio of nano-silica to silane coupling agent KH-550 is (10-20):(1.5-2.5); the mass ratio of aminated nano-silica, emulsifier, isophorone diisocyanate and herbal essential oil is (10-20):(5-7):(15-17):(100-120).

6. The preparation process of a breathable polyurethane foam containing herbal microcapsules according to claim 1, characterized in that: The preparation method of quaternary ammonium salt modified PU prepolymer is as follows: The bio-based PU prepolymer was added to acetone and stirred at 300-400 rpm for 20-30 min. N-methyldiethanolamine was added, and the mixture was stirred at 300-400 rpm for 2-3 h at 40-50 °C. Bromoethane was added dropwise, and the mixture was stirred at 300-400 rpm for 16-20 h at 25-30 °C. After the reaction was completed, the solvent was removed by rotary evaporation. The product was dissolved in tetrahydrofuran and then added to ice-cold diethyl ether to precipitate. The product was filtered and vacuum dried at 30-40 °C for 10-12 h to obtain the quaternary ammonium salt modified PU prepolymer. The mass ratio of bio-based PU prepolymer, N-methyldiethanolamine and bromoethane is (20-25):(3-5):(5-6).

7. The preparation process of a breathable polyurethane foam containing herbal microcapsules according to claim 1, characterized in that: The preparation method of lignin-MDI prepolymer is as follows: Alkaline lignin was added to glycerol and stirred at 300-400 rpm for 20-30 min. Under nitrogen protection, concentrated phosphoric acid was added and stirring was continued for 10-15 min. The reaction was carried out at 80-90℃ and 300-400 rpm for 3-4 h. After the reaction was completed, the mixture was cooled to 50-60℃, potassium carbonate was added to neutralize the system, and then the mixture was dissolved in dichloromethane. The mixture was washed with water and separated. The organic phase was dried with anhydrous magnesium sulfate and filtered. Dichloromethane was removed by rotary evaporation. Polyethylene glycol was added to obtain lignin-based polyol. The lignin-based polyol was dried at 100-120℃ for 1-2 h and then cooled. Under nitrogen protection, polymerized MDI was added dropwise and the mixture was stirred at 80-90℃ and 300-400 rpm for 1-2 h. The -NCO content in the system was measured to be 15-17 wt%. The reaction was stopped and the mixture was cooled to room temperature to obtain lignin-MDI prepolymer. The mass ratio of alkaline lignin, glycerol, concentrated phosphoric acid and polyethylene glycol is (60-70):(100-120):(5-7):(20-30); the mass ratio of lignin-based polyol and polymeric MDI is (20-25):(80-90).

8. The preparation process of a breathable polyurethane foam containing herbal microcapsules according to claim 1, characterized in that: The preparation method of breathable polyurethane foam containing herbal microcapsules is as follows: Organosilicon surfactant, amine catalyst, organobismuth catalyst, and deionized water were added to castor oil polyol and stirred at 300-400 rpm for 20-30 min. Quaternary ammonium salt modified PU prepolymer was added and stirred at 200-300 rpm for 10-15 min. Herbal essential oil / SiO2-polyurea / polyurethane bilayer microcapsules were added and stirred at 100-150 rpm for 5-10 min to obtain polyurethane foam component A. Lignin-MDI prepolymer was mixed with polymeric MDI and stirred at 300-400 rpm for 20-30 min to obtain polyurethane foam component B. Polyurethane foam component A and polyurethane foam component B were mixed to form polyurethane foam slurry and injected into a mold. The slurry was foamed and cured at 50-60℃ for 1-2 h and then cured at 70-80℃ for 1-2 h. The slurry was demolded and aged in a ventilated environment for 36-48 h to obtain breathable polyurethane foam containing herbal microcapsules.

9. The preparation process of a breathable polyurethane foam containing herbal microcapsules according to claim 8, characterized in that: By weight, the polyurethane foam component A comprises: 1-2 parts of silicone surfactant, 0.2-0.3 parts of amine catalyst, 0.1-0.2 parts of organobismuth catalyst, 4-6 parts of deionized water, 60-70 parts of castor oil polyol, 15-20 parts of quaternary ammonium salt modified PU prepolymer and 5-10 parts of herbal essential oil / SiO2-polyurea / polyurethane bilayer microcapsules; By weight, the polyurethane foam component B comprises: 35-40 parts of lignin-MDI prepolymer and 45-50 parts of polymeric MDI.

10. A breathable polyurethane foam containing herbal microcapsules, characterized in that: Prepared according to any one of claims 1-9.

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