Preparation method and application of temperature-sensitive chitosan-based microcapsules based on double emulsion-single coagulation

Abstract

The application discloses a preparation method of temperature-sensitive chitosan-based microcapsules based on double emulsion-single coagulation and application thereof, and the preparation comprises the following steps: reacting vanillin, isocyanate ethyl acrylate and dibutyl tin dilaurate to obtain vanillin modified isocyanate ethyl acrylate, uniformly mixing the vanillin modified isocyanate ethyl acryate with diacetone acrylamide and potassium persulfate, and then heating and reacting to obtain a temperature-sensitive crosslinking agent oligomer; emulsifying water / oil emulsion, chitosan and oil / water emulsifier, and then dropping the temperature-sensitive crosslinking agent oligomer to obtain the temperature-sensitive chitosan-based microcapsules. The temperature-sensitive chitosan microcapsules prepared by the application are green, low-carbon, environment-friendly and biodegradable, can coat water-soluble active substances and oil-soluble active substances at the same time, and have temperature-sensitive controllable release performance; the microcapsules can be coated on the surface of fabrics to obtain fabric coatings. The temperature-sensitive chitosan microcapsules can be applied to the fields of medical protective articles, home textile fabrics, sportswear, curtains, leather products and paper.

Description

TECHNICAL FIELD

[0001] The present application belongs to chemical materials, and particularly relates to a preparation method of a temperature-sensitive chitosan-based microcapsule based on double emulsion-single coagulation and application thereof. BACKGROUND

[0002] Microcapsules are generally microspheres with a core-shell structure and micron-level particle size formed by encapsulating active substances with polymer or inorganic materials as shell materials. The shell layer of the microcapsule plays a role in protecting and sealing the core material and is a key factor determining the performance of the microcapsule. Compared with synthetic polymer materials, natural polymer materials have the advantages of non-toxicity, biodegradability and good biocompatibility, and are most suitable as the shell layer of the microcapsule. However, traditional microcapsule preparation techniques cannot effectively encapsulate highly water-soluble compounds and oil-soluble substances.

[0003] A double emulsion preparation method of a temperature-sensitive polymer microcapsule coated with essential oil is provided in Chinese invention patent (application number: 202210267168.3), which is polymerized by double emulsion droplets arranged from the outside to the inside in the form of oil-water-oil capsule structure, and the outermost side is coated with poly(N-isopropyl acrylamide), which is temperature-sensitive and can realize controlled release of the internal essential oil. Although this microcapsule is prepared by double emulsion, the main purpose is to generate a temperature-sensitive polymer shell layer, so this microcapsule can only coat oil-soluble substances, and the shell material is not a bio-based material. Since it is not a chitosan shell material, it is relatively easy to achieve. Chinese invention patent (application number: 202210805510.0) also discloses a preparation method of a skin care and moisturizing finishing agent based on double-phase microcapsules, which mainly forms a double emulsion. The wall material components in the oil phase are precipitated and deposited on the oil-water interface of the outer water phase and the oil phase and the oil phase and the inner water phase through in-situ polymerization reaction to form an interface film with certain mechanical strength to encapsulate active components. However, the wall material of the microcapsule is a synthetic polymer, and the release of the coated substance can only be achieved by external force such as friction. The release of the internal active substance cannot be controlled. Although this microcapsule is prepared by double emulsion, it is not a chitosan shell material, and the shell material does not have temperature sensitivity. SUMMARY

[0004] The present application provides a preparation method of a temperature-sensitive chitosan-based microcapsule based on double emulsion-single coagulation. The obtained chitosan microcapsule can coat two different active substances of hydrophilicity and oil solubility. The shell material is temperature-sensitive and can control the release of the active substance in the microcapsule. At the same time, the shell material is a chitosan bio-based material, which has the characteristics of green, biodegradability and strong biocompatibility. The microcapsule can be further applied to textile or leather products. Based on the two inactivated substances coated in the microcapsule, the textile or leather can not only have excellent antibacterial performance, but also have certain health and skin care functions.

[0005] The application also provides the application of the temperature-sensitive chitosan-based microcapsule based on double emulsion-single coacervation.

[0006] Technical scheme: In order to achieve the above-mentioned purpose, the application provides a preparation method of a temperature-sensitive chitosan-based microcapsule based on double emulsion-single coacervation, comprising the following steps:

[0007] (1) vanillin, isocyanate acrylate ethyl and dibutyl tin dilaurate are added into acetone, and after reaction, vanillin modified isocyanate acrylate ethyl is obtained;

[0008] (2) vanillin modified isocyanate acrylate ethyl, diacetone acrylamide and potassium persulfate are added into a mixed solution of ethanol and water, and after uniform mixing, heating reaction is carried out to obtain a temperature-sensitive crosslinking agent oligomer;

[0009] (3) water-soluble active substances are added into deionized water to form a uniform aqueous solution, then the solution is added into plant essential oil, and water / oil emulsifier is added to form water / oil emulsion; chitosan, acetic acid and oil / water emulsifier are added into water, and after uniform stirring, a chitosan aqueous solution is formed, then the above-mentioned water / oil emulsion is added into the chitosan aqueous solution, emulsification is carried out, then the emulsion is heated and reacted under continuous mechanical stirring, after reaction, the temperature-sensitive crosslinking agent oligomer aqueous solution is added dropwise, and then continuous stirring reaction is carried out, to obtain a temperature-sensitive chitosan microcapsule emulsion, and the microcapsules are collected by centrifugation.

[0010] In step (1), 2-6 parts of vanillin, 1-5 parts of isocyanate acrylate ethyl and 0.1-0.5 parts of dibutyl tin dilaurate are added into 5-30 parts of acetone by weight, and after reaction at 20-50℃ for 1-6 hours, the precipitate obtained by centrifugation is vanillin modified isocyanate acrylate ethyl.

[0011] In step (2), 3-11 parts of vanillin modified isocyanate acrylate ethyl, 1-5 parts of diacetone acrylamide and 0.1-0.5 parts of potassium persulfate are added into a mixed solution of 50-150 parts of ethanol and water in equal volume by weight, and after uniform mixing, heating to 30-80℃ for 3-8 hours, a temperature-sensitive crosslinking agent oligomer is obtained.

[0012] The temperature-sensitive crosslinking agent oligomer has a number average molecular weight of 1000-8000 g / mol.

[0013] Wherein, in step (3), 1-3 parts of deionized water is added with 0.1-0.5 parts of water-soluble active substance to form a uniform aqueous solution, then the solution is added to 2-8 parts of plant essential oil, 0.1-0.5 parts of water / oil emulsifier is added, and emulsified under ultrasonic conditions to form a water / oil emulsion; 1-3 parts of chitosan, 0.5-1 parts of acetic acid and 0.2-0.8 parts of oil / water emulsifier are added to 50-150 parts of water, stirred uniformly to form a chitosan aqueous solution, then the above water / oil emulsion is added to the chitosan aqueous solution, emulsified under ultrasonic conditions for 10-60 minutes, then the emulsion is heated to 30-70 DEG C, and continuously stirred for 1-3 hours, then 5-10 parts of a warm-sensitive crosslinking agent oligomer aqueous solution (content of 3wt%) is added dropwise, and continuously stirred for 1-3 hours to obtain a warm-sensitive chitosan microcapsule emulsion, and the microcapsules are collected by centrifugation and washed for standby use.

[0014] Wherein, in step (3), the water-soluble active substance is one or several of vitamin C, tea polyphenol, ginsenoside, kelp polysaccharide, Pachyman, cactus polysaccharide, tremella polysaccharide, gypenoside, paeonol, oleuropein, chlorogenic acid, tea polyphenol, grape seed polyphenol, proanthocyanidin and matrine.

[0015] Wherein, in step (3), the plant essential oil is one or several of peppermint essential oil, lemon essential oil, tea tree essential oil, clove oil, lavender oil, rosemary oil, cinnamon oil and thyme oil.

[0016] Wherein, in step (3), the water / oil emulsifier is one or several of steareth-2, PEG-10 dimethicone, glyceryl stearate, glyceryl oleate, polyglyceryl-3 diisostearate, diisostearoyl polyglyceryl-3 dimer dilinoleate, polyglyceryl-6 polyricinoleate, polyglyceryl-2 dipolyhydroxystearate, methyl glucose sesquistearate, sorbitan monooleate and sorbitan stearate; the oil / water emulsifier is one or several of steareth-21, oleth-10, PEG-100 stearate, polyethylene glycol octylphenyl ether, polysorbate-60, cetearyl glucoside, sucrose stearate, potassium cetyl phosphate, sodium cetearyl sulphate and PEG-20 methyl glucose sesquistearate.

[0017] The application discloses a preparation method of a warm-sensitive chitosan-based microcapsule based on a double-emulsion-single-coacervation method.

[0018] Wherein, the preparation method of the microcapsule-treated fabric is as follows:

[0019] (1) according to weight parts, 0.1-0.5 parts of isocyanatoethyl methacrylate is added to 10-50 parts of temperature-sensitive chitosan-based microcapsule water dispersion, then heated to 30-80 DEG C under continuous magnetic stirring, and the reaction is continued for 2-6 hours to obtain a modified microcapsule dispersion;

[0020] (2) according to weight parts, 5-10 parts of water-based UV polyurethane acrylate, 0.1-0.3 parts of a photoinitiator and 0.1-0.5 parts of sodium carboxymethyl cellulose are added to the modified microcapsule dispersion, and a uniform coating is obtained by stirring; the coating is applied to the surface of the fabric, and the coated fabric is dried and cured for 10-60 seconds to obtain a microcapsule-treated fabric.

[0021] The microcapsule-treated fabric described in the application is used in medical protective fabrics, home textile fabrics, sportswear and leather products.

[0022] At present, one finishing of fabric by traditional microcapsule technology can only obtain one function, but the microcapsule prepared by the application can impart antibacterial and skin care functions to the fabric at one finishing, and the shell material of traditional microcapsules is mostly synthetic polymer material, which is not degradable, has poor biocompatibility, and even has a stimulating effect on the skin. The special design of the double emulsion combined with the single coagulation method in the application can impart antibacterial and skin care functions to the fabric at the same time, and the shell material of the chitosan microcapsule is also green, biocompatible, degradable, antibacterial and has other advantages. The chitosan-based microcapsule prepared by the double emulsion combined with the single coagulation method solves the problem that general chitosan microcapsules cannot simultaneously encapsulate two different active substances with very different polarities, so that microcapsules with different properties can be obtained, such as water-soluble active drug VC with antioxidant and skin care, and oil-soluble plant essential oil with antibacterial property.

[0023] At the same time, there are few temperature-sensitive chitosan microcapsules in the prior art, mainly because chitosan is difficult to dissolve in most solvents including water, and the release of traditional microcapsule coating technology is uncontrollable. The chitosan crosslinking agent is designed as a temperature-sensitive crosslinking agent, and then introduced into the shell material of the microcapsule, so that the microcapsule has temperature-responsive release performance, and the active substance encapsulated by the microcapsule can be released controllably by using the body temperature, achieving sustained release and long-term effect. Based on the UV monomer introduced into the shell material of the microcapsule, the UV-curable adhesive can be blended and finished on the surface of the fabric by UV irradiation, which is not only fast, green, energy-saving and emission-reducing, but also can improve the washing and rubbing fastness of the finished fabric.

[0024] The chitosan microcapsule obtained by the double emulsion-single coacervation method can coat two different active substances of hydrophilic and oil-soluble, and the shell material is chitosan biological material, which has the characteristics of green, biodegradable and strong biocompatibility. Since the shell material is temperature-sensitive, the active substance in the microcapsule can be controlled to release, so as to achieve long-lasting release and long-term effect. The microcapsule is further applied to textile or leather products, and based on the two inactivated substances coated in the microcapsule, the textile or leather can not only have excellent antibacterial performance, but also have certain health and skin care functions; based on the UV light curing of the microcapsule, the microcapsule finishing fabric has high fastness, and the finishing process is simple, green, energy-saving and emission-reducing. Meanwhile, the combination of lemon essential oil and chitosan in the microcapsule has very good antibacterial effect.

[0025] Advantages: Compared with the prior art, the present application has the following advantages:

[0026] (1) Based on the biological base structure design, the chitosan microcapsule prepared in the present application is green, low-carbon, environmentally friendly, biodegradable, has good biocompatibility, and the chitosan shell material can synergistically enhance the antibacterial effect with plant essential oil;

[0027] (2) The microcapsule synthesized by the double emulsion-single coacervation method can coat water-soluble active substances and oil-soluble active substances at the same time;

[0028] (3) By introducing a temperature-sensitive crosslinking agent, the microcapsule prepared in the present application not only has high mechanical properties, but also has temperature-sensitive controlled release performance;

[0029] (4) Since the surface of the microcapsule is modified, the microcapsule can be coated on the surface of the fabric by mixing with a UV light curing adhesive, and a fabric coating is obtained by UV light curing, and the whole process is fast, green and energy-saving and emission-reducing;

[0030] (5) The method for preparing the temperature-sensitive chitosan microcapsule is simple, has few steps, and the prepared microcapsule has high stability;

[0031] (6) The temperature-sensitive chitosan microcapsule prepared in the present application can be applied to medical protective products, home textile fabrics, sportswear, curtains, leather products and paper. BRIEF DESCRIPTION OF DRAWINGS

[0032] Figure 1 It is a schematic diagram of the preparation process of the temperature-sensitive chitosan microcapsule of Example 1 of the present application.

[0033] Figure 2For the stability of the microcapsule emulsion in Example 1 of the present application after 7 days, the microcapsule emulsion was placed at room temperature for 7 days, and it was found that the control emulsion (0.2 parts of oleyl polyether-10 was changed to 0.1 part of oleyl polyether-10 in Example 1) had obvious layering phenomenon, while the emulsion of Example 1 did not have obvious layering phenomenon, indicating that the microcapsule emulsion was very stable.

[0034] Figure 3 For the preparation of the chitosan microcapsule in Example 1 of the present application, (a and b) optical microscope images of the water / oil / water double emulsion before and after preparation; (c) SEM image of the chitosan microcapsule, (d) magnified SEM image of the chitosan microcapsule; (e) TEM image of the chitosan microcapsule; (f) EDS and mapping images of the chitosan microcapsule.

[0035] Figure 4 For the release curve of the microcapsule lemon essential oil and VC in Example 1 of the present application, (a) standard curve of lemon essential oil; (b, c) temperature-sensitive release characteristics of lemon essential oil from chitosan microcapsules at 20℃ and 40℃, respectively. (d) standard curve of VC; (e) stability comparison of microencapsulated and non-encapsulated VC; (f) release characteristics of VC from chitosan microcapsules at 20℃.

[0036] Figure 5 For the process of treating fabric with chitosan microcapsules in Example 1 of the present application, (a) schematic diagram of cross-linked network film formed on the surface of fabric based on modified chitosan microcapsules and ultraviolet-cured acrylic adhesive; (b and c) cotton fabric printed with butterfly and flower patterns by using water-based pigment paste of modified chitosan microcapsules; (d and e) SEM images of uncoated cotton fabric and microcapsule-coated cotton fabric containing water-based pigment paste, (f and g) magnified SEM images of microcapsule-coated cotton fabric; (h) EDS and mapping images of microcapsule-treated cotton fabric.

[0037] Figure 6 For the antibacterial durability of chitosan microcapsule-treated fabric in Example 1 of the present application, (a) trend graph of the residual rate of VC and lemon essential oil of microcapsule-treated fabric and control fabric with time; (b) change in residual rate of lemon essential oil of microcapsule-treated fabric and control fabric after different washing cycles; (c) change in residual rate of lemon essential oil of microcapsule-treated fabric and control fabric after different wear cycles.

[0038] Figure 7(a) Schematic diagram of the antibacterial and skin care properties of the chitosan microcapsule treated fabric; (b) Bacterial photographs of different surface colony counts (b1: original cotton fabric, b2: chitosan treated control fabric, b3: control fabric treated with lemon essential oil, b4: chitosan microcapsule treated fabric); (c) Histogram of the antibacterial rate of the chitosan or essential oil treated control fabric and the microcapsule treated fabric; (d, e) Escherichia coli and Staphylococcus aureus antibacterial rates of the microcapsule treated fabric and the essential oil treated control fabric after 30 days of placement. DETAILED DESCRIPTION

[0039] The present application is further illustrated by the following examples.

[0040] The raw materials used in the examples of the present application are commercially available or can be obtained by using commercially available raw materials of the same type.

[0041] The chitosan has a molecular weight of 150,000, and the essential oils are commercially available oil-soluble essential oils.

[0042] Example 1

[0043] (1) According to the weight parts, first, 3 parts of vanillin, 2 parts of isocyanate acrylate ethyl ester, and 0.2 parts of dibutyl tin dilaurate are added to 10 parts of acetone, and after reaction at 30°C for 5 hours, the precipitate is obtained by centrifugation at 8000 rpm for 5 minutes to obtain vanillin modified isocyanate acrylate ethyl ester.

[0044] (2) According to the weight parts, 4 parts of vanillin modified isocyanate acrylate ethyl ester, 2 parts of diacetone acrylamide, and 0.2 parts of potassium persulfate are added to 70 parts of a mixed solution of ethanol and water (volume ratio 1:1), and after mixing uniformly, the solution is heated to 40°C for 7 hours to obtain a solution of the temperature-sensitive crosslinking agent oligomer.

[0045] (3) By weight, 0.2 parts of vitamin C was added to 2 parts of deionized water to form a uniform aqueous solution, then the solution was added to 3 parts of lemon essential oil, 0.2 parts of glyceryl stearate was added, and emulsified under ultrasonic conditions for 15 minutes to form a water / oil emulsion; 2 parts of chitosan (molecular weight 150,000), 0.6 parts of acetic acid and 0.3 parts of oleyl polyether-10 were added to 70 parts of deionized water, and after stirring uniformly, a chitosan aqueous solution was formed, then the above water / oil emulsion was added to the chitosan aqueous solution (maintaining the proportion of 0.2 parts of glyceryl stearate and 0.3 parts of oleyl polyether-10 was added in total), and emulsified under ultrasonic conditions for 10 minutes, then the emulsion was heated to 30°C, and after continuous mechanical stirring (400 rpm) for 3 hours, 6 parts of a warm-sensitive crosslinking agent oligomer aqueous solution (content 3wt%, the solution obtained from step (2) was centrifuged and then dispersed to prepare) was added dropwise, and after continuous stirring (400 rpm) for 2 hours, a warm-sensitive chitosan microcapsule emulsion was obtained, which was centrifuged at a speed of 8000 rpm / min for 10 minutes, and the lower precipitate was collected as the microcapsule, which was washed and reserved.

[0046] (4) By weight, 0.2 parts of isocyanatoethyl methacrylate was added to 20 parts of the above microcapsule aqueous dispersion (solid content 10wt%), then heated to 40°C under continuous magnetic stirring (300 rpm), and reacted for 5 hours to obtain a modified microcapsule dispersion.

[0047] (5) By weight, 6 parts of water-based UV polyurethane acrylate (Nanjing Ji Zhong Chemical Technology Co., Ltd., model: JZ-307, solid content 40wt%), 0.2 parts of photoinitiator 1173 and 0.2 parts of sodium carboxymethyl cellulose were added to the above modified microcapsule dispersion (maintaining the proportion of 0.2 parts of isocyanatoethyl methacrylate and 0.2 parts of sodium carboxymethyl cellulose was added), and stirred with a mechanical stirrer at a speed of 600 rpm for 10 minutes to obtain a uniform coating; a printing screen was placed on a cotton fabric, then the coating was poured onto the printing screen, and spread on the surface of the fabric with a squeegee, the coated fabric was dried at 60°C for 3 minutes, then cured under UV light (365 nm) for 45 seconds to obtain a microcapsule treated fabric, and the coating thickness was 200μm.

[0048] Example 2

[0049] (1) By weight, 6 parts of vanillin, 5 parts of isocyanate acrylate ethyl ester and 0.5 parts of dibutyltin dilaurate were added to 30 parts of acetone, and after reacting at 50°C for 1 hour, the precipitate was obtained by centrifugation at 8000 rpm for 5 minutes to obtain vanillin modified isocyanate acrylate ethyl ester.

[0050] (2) By weight parts, 11 parts of vanillin modified isocyanate acrylate, 5 parts of diacetone acrylamide and 0.5 parts of potassium persulfate are added into 150 parts of ethanol and water mixed solution (volume ratio of 1:1), after mixing uniformly, heated to 80℃ for 3 hours to obtain a temperature-sensitive crosslinking agent oligomer solution.

[0051] (3) By weight parts, 0.5 parts of tea polyphenol is added into 3 parts of deionized water to form a uniform aqueous solution, then the solution is added into 8 parts of thyme oil, 0.5 parts of polyglycerol-3 diisostearate is added, and emulsified under ultrasonic conditions for 15 minutes to form a water / oil emulsion; 3 parts of chitosan, 1 part of acetic acid and 0.8 parts of polyethylene glycol octylphenyl ether are added into 150 parts of deionized water, stirred uniformly to form a chitosan aqueous solution, then the above water / oil emulsion is added into the chitosan aqueous solution (maintaining the proportion of 0.5 parts of polyglycerol-3 diisostearate and 0.8 parts of polyethylene glycol octylphenyl ether is added in total), emulsified under ultrasonic conditions for 60 minutes, then the emulsion is heated to 70℃, and after 1 hour of reaction under continuous mechanical stirring (400 rpm), 10 parts of temperature-sensitive crosslinking agent oligomer aqueous solution (content of 3wt%, the solution obtained from step (2) is centrifuged and then dispersed again) is added dropwise, and after 1 hour of continuous stirring (400 rpm) reaction, a temperature-sensitive chitosan microcapsule emulsion is obtained, which is centrifuged at a speed of 8000 rpm for 10 minutes, and the lower precipitate is collected as the microcapsule, which is washed and reserved.

[0052] (4) By weight parts, 0.5 parts of isocyanatoethyl methacrylate is added into 50 parts of the above microcapsule aqueous dispersion (solid content of 10wt%), then heated to 80℃ under continuous magnetic stirring (300 rpm) for 2 hours to obtain a modified microcapsule dispersion.

[0053] (5) By weight parts, 10 parts of water-based UV polyurethane acrylate (Nanjing Ji Zhong Chemical Technology Co., Ltd., model: JZ-307, solid content of 40wt%), 0.3 parts of photoinitiator 1173 and 0.5 parts of sodium carboxymethyl cellulose are added into the above modified microcapsule dispersion (maintaining the proportion of 0.5 parts of isocyanatoethyl methacrylate and 0.5 parts of sodium carboxymethyl cellulose is added), and stirred with a mechanical stirrer at a speed of 600 rpm for 10 minutes to obtain a uniform coating; the printing screen is placed on the leather, then the coating is poured into the printing screen, and the coating is applied on the surface of the fabric with a squeegee, the coated leather is dried at 60℃ for 3 minutes, then cured under UV light (365nm) for 10 seconds to obtain a microcapsule treated fabric, and the coating thickness is 200μm.

[0054] Example 3

[0055] (1) According to weight parts, 2 parts of vanillin, 1 part of isocyanate acrylate ethyl ester and 0.1 part of dibutyl tin dilaurate are added into 5 parts of acetone, and after reaction at 20°C for 6 hours, the precipitate is obtained by centrifugation at 8000 rpm for 5 minutes, to obtain vanillin modified isocyanate acrylate ethyl ester.

[0056] (2) According to weight parts, 3 parts of vanillin modified isocyanate acrylate ethyl ester, 1 part of diacetone acrylamide and 0.1 part of potassium persulfate are added into 50 parts of a mixed solution of ethanol and water (volume ratio of 1:1), and after mixing uniformly, the solution is heated to 30°C for reaction for 3 hours to obtain a temperature-sensitive crosslinking agent oligomer.

[0057] (3) According to weight parts, 0.1 part of sophoridine is added into 1 part of deionized water to form a uniform aqueous solution, and then the solution is added into 2 parts of lavender oil, 0.1 part of polyglycerol-2 dimeric hydroxystearate is added, and an oil / water emulsion is formed under ultrasonic conditions for 15 minutes; 1 part of chitosan, 0.5 part of acetic acid and 0.2 part of cetearyl glucoside are added into 50 parts of deionized water, and after stirring uniformly, a chitosan aqueous solution is formed, and then the above-mentioned oil / water emulsion is added into the chitosan aqueous solution (maintaining the proportion of 0.1 part of polyglycerol-2 dimeric hydroxystearate and 0.2 part of cetearyl glucoside is added in total), and emulsified under ultrasonic conditions for 10 minutes, and then the emulsion is heated to 30°C, and after reaction for 4 hours under continuous mechanical stirring (400 rpm), 5 parts of a temperature-sensitive crosslinking agent oligomer aqueous solution (content of 3 wt%, the solution obtained in step (2) is centrifuged and then dispersed again) is added dropwise, and after continuous stirring (400 rpm) for 3 hours, a temperature-sensitive chitosan microcapsule emulsion is obtained, and after centrifugation at a speed of 8000 revolutions per minute for 10 minutes, the lower precipitate is collected to obtain the microcapsule, which is washed and reserved.

[0058] (4) According to weight parts, 0.1 part of isocyanatoethyl methacrylate is added into 10 parts of the above-mentioned microcapsule aqueous dispersion (solid content of 10 wt%), and then heated to 30°C under continuous magnetic stirring (300 rpm) for reaction for 6 hours to obtain a modified microcapsule dispersion.

[0059] (5) According to parts by weight, 5 parts of water-based UV polyurethane acrylate (Nanjing Jiachuang Chemical Technology Co., Ltd., model: JZ-307, solid content is 40wt%), 0.1 part of photoinitiator 1173 and 0.1 part of sodium carboxymethyl cellulose are added to the above modified microcapsule dispersion solution (maintain the proportion of 0.1 part of isocyanatoethyl methacrylate and 0.1 part of sodium carboxymethyl cellulose is added), and a uniform coating is obtained by stirring with a mechanical stirrer at a speed of 600 rpm for 10 minutes; the printing screen is placed on the polyester-cotton fabric, then the mixture is poured into the printing screen, and the coating is applied on the surface of the fabric with a scraper, and the coated fabric is dried at 60℃ for 3 minutes, and then cured under UV light (365nm) for 45 seconds to obtain a microcapsule treated fabric, and the coating thickness is 200μm.

[0060] Example 4

[0061] (1) According to parts by weight, 4 parts of vanillin, 3 parts of isocyanate acrylate ethyl ester and 0.3 parts of dibutyltin dilaurate are added to 15 parts of acetone, and after reaction at 35℃ for 4 hours, the precipitate is obtained by centrifugation at 8000 rpm for 5 minutes to obtain vanillin modified isocyanate acrylate ethyl ester.

[0062] (2) According to parts by weight, 6 parts of vanillin modified isocyanate acrylate ethyl ester, 3 parts of diacetone acrylamide and 0.3 parts of potassium persulfate are added to 100 parts of a mixed solution of ethanol and water (volume ratio 1:1), and after mixing uniformly, heating to 50℃ for 5 hours to obtain a solution of temperature-sensitive crosslinking agent oligomer.

[0063] (3) According to parts by weight, 0.3 parts of chlorogenic acid are added to 2 parts of deionized water to form a uniform aqueous solution, then the solution is added to 5 parts of clove oil, 0.3 parts of sorbitan monooleate are added, and emulsified under ultrasonic conditions for 15 minutes to form a water / oil emulsion; 2 parts of chitosan, 0.8 parts of acetic acid and 0.5 parts of potassium cetyl phosphate are added to 100 parts of deionized water, and after stirring uniformly, a chitosan aqueous solution is formed, then the above water / oil emulsion is added to the chitosan aqueous solution (maintain the proportion of 0.3 parts of sorbitan monooleate and 0.5 parts of potassium cetyl phosphate is added), and emulsified under ultrasonic conditions for 40 minutes, then the emulsion is heated to 50℃, and after continuous mechanical stirring (400 rpm) for 2 hours, 7 parts of temperature-sensitive crosslinking agent oligomer aqueous solution (content is 3wt%, the solution obtained in step (2) is centrifuged and then dispersed to prepare) is added dropwise, and after continuous stirring for 2.5 hours, a temperature-sensitive chitosan microcapsule emulsion is obtained, which is centrifuged at a speed of 8000 revolutions per minute for 10 minutes, and the lower precipitate is collected as the microcapsule, which is washed and reserved.

[0064] (4) According to parts by weight, 0.3 parts of isocyanatoethyl methacrylate is added to 30 parts of the above-mentioned microcapsule aqueous dispersion (solid content of 10 wt%), then heated to 60°C under continuous magnetic stirring (300 rpm) for 4.5 hours to obtain a modified microcapsule dispersion.

[0065] (5) According to parts by weight, 7 parts of water-based UV polyurethane acrylate (Nanjing Jiazhong Chemical Technology Co., Ltd., model: JZ-307, solid content of 40 wt%), 0.2 parts of photoinitiator 1173 and 0.3 parts of sodium carboxymethyl cellulose are added to the above-mentioned modified microcapsule dispersion (maintaining the proportion of 0.3 parts of isocyanatoethyl methacrylate and 0.3 parts of sodium carboxymethyl cellulose), and stirred with a mechanical stirrer at a speed of 600 rpm for 10 minutes to obtain a uniform coating; the printing screen is placed on the polyester fabric, then the coating is poured onto the printing screen, and the coating is applied to the surface of the fabric with a scraper, and the coated fabric is dried at 60°C for 3 minutes, then cured under UV light (365 nm) for 35 seconds to obtain a microcapsule treated fabric, and the coating thickness is 200 μm.

[0066] Example 5

[0067] (1) According to parts by weight, 5 parts of vanillin, 4 parts of isocyanate acrylate ethyl ester and 0.45 parts of dibutyltin dilaurate are added to 25 parts of acetone, and after reaction at 35°C for 2.5 hours, the precipitate is obtained by centrifugation at 8000 rpm for 5 minutes to obtain vanillin modified isocyanate acrylate ethyl ester.

[0068] (2) According to parts by weight, 9 parts of vanillin modified isocyanate acrylate ethyl ester, 4 parts of diacetone acrylamide and 0.5 parts of potassium persulfate are added to 125 parts of a mixed solution of ethanol and water (volume ratio of 1:1), and after mixing and heating to 70°C for 4.5 hours, a warm-sensitive crosslinking agent oligomer is obtained.

[0069] (3) By weight, 0.4 parts of Pachyman polysaccharide was added to 2 parts of deionized water to form a uniform aqueous solution, then the solution was added to 7 parts of cinnamon oil, 0.4 parts of polyglycerol-6 polyricinoleate was added, and emulsified under ultrasonic conditions for 15 minutes to form a water / oil emulsion; 3 parts of chitosan, 1 part of acetic acid and 0.5 part of PEG-100 stearate were added to 140 parts of deionized water, and stirred uniformly to form a chitosan aqueous solution, then the above water / oil emulsion was added to the chitosan aqueous solution (maintaining the proportion of 0.4 parts of polyglycerol-6 polyricinoleate and 0.5 parts of polyethylene glycol octylphenyl ether to be added in total), and emulsified under ultrasonic conditions for 50 minutes, then the emulsion was heated to 60°C, and reacted for 2 hours under continuous mechanical stirring (400 rpm), then 9 parts of a warm-sensitive crosslinking agent oligomer aqueous solution (content of 3wt%, prepared by centrifugation of the solution obtained in step (2) and then re-dispersed) was added dropwise, and the reaction was continued for 2 hours under continuous stirring, to obtain a warm-sensitive chitosan microcapsule emulsion, which was centrifuged at a speed of 8000 rpm for 10 minutes, and the lower precipitate was collected as the microcapsule, which was washed and reserved.

[0070] (4) By weight, 0.45 parts of isocyanatoethyl methacrylate was added to 45 parts of the above microcapsule aqueous dispersion (solid content of 10wt%), then heated to 45°C under continuous magnetic stirring (300 rpm), and the reaction was continued for 3.5 hours, to obtain a modified microcapsule dispersion.

[0071] (5) By weight, 9 parts of water-based UV polyurethane acrylate (Nanjing Ji Zhong Chemical Technology Co., Ltd., model: JZ-307, solid content of 40wt%), 0.25 parts of photoinitiator 1173 and 0.4 parts of sodium carboxymethyl cellulose were added to the above modified microcapsule dispersion (maintaining the proportion of 0.45 parts of isocyanatoethyl methacrylate and 0.4 parts of sodium carboxymethyl cellulose to be added), and stirred with a mechanical stirrer at a speed of 600 rpm for 10 minutes to obtain a uniform coating; a printing screen was placed on a paper, then the coating was poured onto the printing screen, and spread on the surface of the fabric with a squeegee, the coated paper was dried at 60°C for 3 minutes, then cured under UV light (365 nm) for 25 seconds to obtain a microcapsule treated fabric, and the coating thickness was 200μm.

[0072] Test Example 1

[0073] The warm-sensitive chitosan microcapsules were prepared according to the method of Example 1 and applied to the surface of the fabric, Figure 1 are the specific operation steps for the synthesis of microcapsules, and the microcapsules prepared by Example 1 were characterized and tested.

[0074] Figure 2The stability of the microcapsule emulsion prepared in Example 1 (temperature-sensitive chitosan microcapsule emulsion prepared in step (3) in Example 1) was observed after being placed at room temperature for 7 days. It was found that the control emulsion (0.2 parts of oleth-10 was replaced by 0.1 parts of oleth-10 in Example 1) had obvious stratification, while the emulsion of Example 1 did not have obvious stratification, indicating that the microcapsule emulsion was very stable.

[0075] Figure 3 The morphology of the chitosan microcapsules formed during the preparation of Example 1 was observed by optical microscopy, scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The particle size of the chitosan microcapsules was about 3 μm, and the main chemical elements on the surface of the microcapsules were carbon, nitrogen and oxygen, as characterized by energy dispersive spectroscopy (EDS), indicating that the microcapsule shell material was mainly composed of chitosan.

[0076] Figure 4 The temperature-sensitive release curve of the essential oil of the chitosan microcapsules prepared in Example 1 was determined. Test method: whether the microcapsules had temperature-responsive release performance was determined by ultraviolet-visible spectrophotometry. A certain amount of lemon essential oil was weighed and dissolved in cyclohexane to prepare five kinds of lemon essential oil-cyclohexane solutions with different concentrations (0.005 mg / mL, 0.01 mg / mL, 0.02 mg / mL, 0.04 mg / mL and 0.08 mg / mL), and the absorbance of the five solutions in the wavelength range of 200-400 nm was measured by ultraviolet-visible spectrophotometry, and a standard curve was drawn. The microcapsule solution sample was placed in an environment of 20°C and 40°C, respectively, and the absorbance of the sample in the wavelength range of 200-400 nm was measured every 5 days, and the concentration was calculated by substituting the value into the standard curve equation, and the release rate of the essential oil was calculated. Figure 4 a and 4d are the standard curves of lemon essential oil and VC, respectively. According to the R 2 value, the curve fitting effect is good. As shown in Figure 4 b and Figure 4 c, after the microcapsules were placed at 20°C for 30 days, the release amount of the essential oil reached about 70 wt%, while when the chitosan microcapsules were placed at 40°C for 30 days, the release amount of the essential oil in the microcapsules reached 80 wt%, indicating that the release rate of the essential oil from the microcapsules could be adjusted by changing the temperature, which was mainly due to the introduction of temperature-sensitive polymers in the chitosan shell material. In addition, VC is not stable under normal conditions. As shown in Figure 4 e, after being exposed to air for 35 days, the active ingredient content of VC was only 45%, while the active ingredient content of VC in the chitosan microcapsules remained above 90%, indicating that the chitosan microcapsules had a dual protection effect. When the chitosan microcapsules were placed at 20°C for 30 days, the release rate of VC was lower than that of the essential oil, and the final residual content of VC in the microcapsules was about 37 wt% (Figure 4 f), which is mainly due to the double protection of the essential oil and the chitosan shell.

[0077] The microcapsules prepared in Example 1 were used to treat cotton fabrics by mixing with a modified UV-curable adhesive, and the treated fabrics were obtained. The preparation process is as follows Figure 5 a. As shown in Figure 5 b and 5c, the aqueous color paste containing the modified chitosan microcapsules can print different patterns on the fabric according to different needs, which proves that the microcapsules prepared in the present application can be printed and cured on the surface of the fabric, and the printed pattern is clear. Using SEM images, it can be observed that the surface of the cotton fabric coated with the film layer is rough and has many protrusions compared with the smooth surface of the original cotton fabric Figure 5 d-g), which is mainly due to the addition of the modified chitosan microcapsules prepared in the present application. Further analysis of the chemical composition of the fabric surface was carried out using EDS, as shown in Figure 5 h, the fabric surface is uniformly covered with C, O and N elements, which further proves that the chitosan microcapsules are uniformly covered on the fabric.

[0078] The chitosan microcapsules prepared in Example 1 were used to treat fabrics, and the aroma retention effect and durability of the coated cotton fabric were further studied. As shown in Figure 6 a, after 30 days at room temperature, the remaining amount of VC or essential oil in the fabric treated with pure VC or lemon essential oil (using the method of Example 1, replacing the chitosan microcapsules with pure VC or lemon essential oil) is less than 30%. However, the cotton fabric coated with microcapsules still has more than 30% of the remaining VC or essential oil even after 90 days, which indicates that the cotton fabric coated with microcapsules has a good slow-release effect of VC and essential oil. Further water washing (refer to GB / T 3921-2008) and abrasion (refer to GB / T 4802.2-2008, Martin Dale method) tests were carried out to test the water washing and abrasion resistance of the treated fabric. After ten washing or abrasion cycles, the remaining rate of essential oil in the coated fabric is 30% and 45% respectively Figure 6 b and Figure 6 c). While the remaining rate of essential oil in the fabric treated with pure lemon essential oil is almost zero after ten washing or abrasion cycles. All these results show that the fabric coated with microcapsules has a long-lasting aroma retention effect, and can be used for a long time regardless of washing or abrasion.

[0079] Antibacterial experiments were performed on fabrics treated with the chitosan microcapsules prepared in Example 1. Control fabrics (0.04 g) and microcapsule-treated fabrics (0.04 g) were shaken at 37°C in a shaker with bacterial solution (0.1 mL of original bacterial solution in the logarithmic growth phase and 0.9 mL of PBS solution) at 135 r / min for 18 h. Then the bacterial solution was dropped on a plate for culture, and the growth of E. coli and S. aureus on the plate was observed and the antibacterial rate was calculated. Figure 7 aIt was found that the active ingredient was encapsulated in the microcapsules and was released slowly when the coated fabric contacted the skin, thereby enhancing the immunity and antibacterial properties of the body. The original fabric had no antibacterial effect compared to other treated fabrics (chitosan and essential oil were directly treated on the fabric, and the chitosan microcapsules were replaced with pure chitosan or lemon essential oil using the method of Example 1). However, after 1000-fold dilution of the bacterial concentration, there were almost no E. coli and S. aureus on the fabric treated directly with essential oil, and the antibacterial rate reached above 99%, indicating that the fabric treated with essential oil had excellent antibacterial properties. In addition, the fabric treated with microcapsules also had good antibacterial properties, with an antibacterial rate of above 97%, which may be due to the synergistic effect of essential oil and chitosan as the shell material Figure 7 band 7c). Although the antibacterial rate was slightly lower than that of the fabric treated with essential oil (because the essential oil was wrapped), the addition of essential oil microcapsules could improve the durability of the antibacterial effect of the fabric. According to Figure 7 dand 7e, compared with the fabric treated directly with essential oil, the antibacterial rate of the fabric coated with microcapsules remained above 90% for E. coli and S. aureus even after 30 days, while the antibacterial effect of the fabric treated directly with essential oil decreased significantly, indicating that it had better durability of antibacterial properties and could be used for a long time.

Claims

1. A process for the preparation of temperature-sensitive chitosan-based microcapsules based on double emulsion-single coacervation, characterized by, The method comprises the following steps: (1) adding vanillin, isocyanate acrylate ethyl ester and dibutyl tin dilaurate into acetone, and obtaining vanillin modified isocyanate acrylate ethyl ester after reaction; (2) adding vanillin modified isocyanate acrylate ethyl ester, diacetone acrylamide and potassium persulfate into a mixed solution of ethanol and water, uniformly mixing, and then heating to obtain a temperature-sensitive crosslinking agent oligomer after reaction; (3) adding a water-soluble active substance into deionized water to form a uniform aqueous solution, then adding the solution into a plant essential oil, adding a water / oil emulsifier, and emulsifying to form a water / oil emulsion; adding chitosan, acetic acid and an oil / water emulsifier into water, uniformly stirring to form a chitosan aqueous solution, then adding the above water / oil emulsion into the chitosan aqueous solution, emulsifying under ultrasonic conditions for 10-60 minutes, then heating the emulsion to 30-70 DEG C and continuously stirring to react for 1-3 hours, then adding a temperature-sensitive crosslinking agent oligomer aqueous solution dropwise, continuously stirring to react for 1-3 hours, obtaining a temperature-sensitive chitosan microcapsule emulsion, and centrifugally collecting the microcapsules.

2. The production method according to claim 1, characterized by, In step (1), 2-6 parts of vanillin, 1-5 parts of isocyanate acrylate ethyl ester and 0.1-0.5 parts of dibutyl tin dilaurate are added into 5-30 parts of acetone, and the mixture is reacted at 20-50 DEG C for 1-6 hours, and then centrifuged to obtain a precipitate, which is vanillin modified isocyanate acrylate ethyl ester.

3. The production method according to claim 1, characterized by, In step (2), 3-11 parts of vanillin modified isocyanate acrylate ethyl ester, 1-5 parts of diacetone acrylamide and 0.1-0.5 parts of potassium persulfate are added into a mixed solution of 50-150 parts of ethanol and water, wherein the ethanol and water are in equal volume ratio, uniformly mixing, and then heating to 30-80 DEG C to react for 3-8 hours to obtain a temperature-sensitive crosslinking agent oligomer.

4. The method of claim 1, wherein, In step (3), 1-3 parts of deionized water is added with 0.1-0.5 parts of a water-soluble active substance to form a uniform aqueous solution, then the solution is added into 2-8 parts of a plant essential oil, 0.1-0.5 parts of a water / oil emulsifier is added, and the mixture is emulsified under ultrasonic conditions to form a water / oil emulsion; 1-3 parts of chitosan, 0.5-1 parts of acetic acid and 0.2-0.8 parts of an oil / water emulsifier are added into 50-150 parts of water, uniformly stirring to form a chitosan aqueous solution, then the above water / oil emulsion is added into the chitosan aqueous solution, emulsifying under ultrasonic conditions for 10-60 minutes, then the emulsion is heated to 30-70 DEG C and continuously stirred to react for 1-3 hours, then 5-10 parts of a temperature-sensitive crosslinking agent oligomer aqueous solution is added dropwise, continuously stirring to react for 1-3 hours to obtain a temperature-sensitive chitosan microcapsule emulsion, and the microcapsules are centrifugally collected and washed for standby use.

5. The preparation method according to claim 1, characterized in that, The water-soluble active substance in step (3) is one or more of vitamin C, tea polyphenol, ginsenoside, kelp polysaccharide, grifola polysaccharide, cactus polysaccharide, tremella polysaccharide, gynostemma pentaphyllum saponin, paeonol, oleuropein, chlorogenic acid, tea polyphenol, grape seed polyphenol, proanthocyanidin and sophora alkaloid.

6. The method of claim 1, wherein, The plant essential oil in step (3) is one or more of peppermint essential oil, lemon essential oil, tea tree essential oil, clove oil, lavender oil, rosemary oil, cinnamon oil and thyme oil.

7. The preparation method according to claim 1, characterized in that, The water / oil emulsifier in step (3) is one or more of steareth-2, PEG-10 dimethicone, glyceryl stearate, glyceryl oleate, polyglyceryl-3 diisostearate, diisostearoyl polyglyceryl-3 dimer dilinoleate, polyglyceryl-6 polyricinoleate, polyglyceryl-2 dipolyhydroxystearate, methyl glucose sesquistearate, sorbitan monooleate and sorbitan stearate; the oil / water emulsifier is one or more of steareth-21, oleth-10, PEG-100 stearate, polyethylene glycol octylphenyl ether, polysorbate-60, cetearyl glucoside, sucrose stearate, potassium cetyl phosphate, sodium cetearyl sulphate and PEG-20 methyl glucose sesquistearate.

8. The use of the temperature-sensitive chitosan-based microcapsules prepared by the method for preparing the temperature-sensitive chitosan-based microcapsules based on double emulsion-single coacervation of claim 1 in the preparation of microcapsule-treated fabrics.

9. Use according to claim 8, characterized in that, The method for preparing the microcapsule-treated fabrics is as follows: (1) 0.1-0.5 parts of isocyanatoethyl methacrylate is added to 10-50 parts of the aqueous dispersion of the temperature-sensitive chitosan-based microcapsules, and then heated to 30-80°C under continuous magnetic stirring for 2-6 hours to obtain a modified microcapsule dispersion; (2) 5-10 parts of water-based UV polyurethane acrylate, 0.1-0.3 parts of a photoinitiator and 0.1-0.5 parts of sodium carboxymethyl cellulose are added to the modified microcapsule dispersion, and stirred to obtain a uniform coating; The coating is applied to the surface of the fabric, and the coated fabric is dried and then cured for 10-60 seconds to obtain a microcapsule-treated fabric.

10. The use of the temperature-sensitive chitosan-based microcapsules prepared by the method for preparing the temperature-sensitive chitosan-based microcapsules based on double emulsion-single coacervation of claim 1 in medical protective fabrics, home textile fabrics, sportswear and leather products.

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