Antibacterial microcapsule as well as preparation method and application thereof

Abstract

The invention relates to the technical field of fabric after-finishing, and discloses an antibacterial microcapsule as well as a preparation method and application thereof. According to the method, the polyethylene glycol modified melamine-formaldehyde prepolymer and the essence emulsion are prepared respectively, and then the antibacterial microcapsule disclosed by the invention is prepared. The antibacterial microcapsule has a core-shell structure, a shell of the antibacterial microcapsule is made of melamine-formaldehyde resin modified by polyethylene glycol, a capsule core of the antibacterial microcapsule is made of aromatic essential oil, and the shell of the melamine-formaldehyde resin modified by polyethylene glycol has good heat resistance, so that the antibacterial microcapsule is prevented from being decomposed in a high-temperature environment; the slow release function of the antibacterial component and the aromatic component is destroyed. The shell of the antibacterial microcapsule contains an antibacterial component, and the capsule core contains an aromatic component, so that when the antibacterial microcapsule is applied to preparation of the antibacterial fabric, harmful bacteria on the fabric can be quickly and efficiently removed, and meanwhile, the aromatic odor of the fabric is kept for a long time.

Description

Technical Field

[0001] The invention relates to the technical field of fabric finishing, and in particular to an antibacterial microcapsule and a preparation method and application thereof. Background Art

[0002] The preparation of functional microcapsules has developed rapidly, from low fragrance content to high fragrance content; from single specific effects to multifunctionality. As we all know, aromatic microcapsules have no binding force with fabrics. Adhesives and cross-linking agents are usually used to attach microcapsules to the surface of fabrics. Due to the volatility of essential oils, it is difficult to release fragrance on the surface of fabrics for a long time. After high-temperature drying, the fragrance left on the surface of the fabric is either less or less persistent.

[0003] In order to solve the problem of poor sustained release persistence of microcapsules, patent application CN102127864A discloses a preparation method of preparing double-shell microcapsules by preparing melamine-formaldehyde resin as shell, lavender essential oil as capsule core, and then adding adhesive VAE solution to the outer wall material to increase the fragrance persistence; patent application CN107858833A discloses a microcapsule preparation with lavender and wormwood compounded as capsule core and polymer material as wall material, and after finishing on fabric, the underwear has antibacterial, antipruritic, sustained release fragrance and other multifunctional functions. The patent prepares antibacterial and deodorizing microcapsules by compounding lavender essential oil and polyhexamethylene biguanide hydrochloride as capsule core and polymer material as capsule skin, which is suitable for microcapsule finishing agent of cotton socks, but the shell of the antibacterial and deodorizing microcapsules described in the patent has poor heat resistance and can only be used in low temperature environment. Patent application CN112724827A discloses a method of modifying the shell to give the microcapsules hydrophobicity and UV resistance, while loading flavors into the microcapsules to obtain strawberry-shaped microcapsules that integrate multiple functions such as flavor sustained release, super hydrophobicity and UV resistance. However, the patent has a slow sterilization process and requires a long time to achieve a good sterilization effect. Summary of the invention

[0004] The purpose of the present invention is to overcome the problem that the existing antibacterial microcapsules are difficult to apply in high temperature environments and have slow sterilization, and to provide an antibacterial microcapsule and a preparation method and application thereof. The antibacterial microcapsule has good heat resistance, good sterilization effect and high efficiency through the design and optimization of the shell components, and can retain the aromatic smell of the fabric for a long time.

[0005] In order to achieve the above object, the present invention provides a method for preparing antibacterial microcapsules in a first aspect, the method comprising the following steps:

[0006] (1) Preparation of polyethylene glycol modified melamine-formaldehyde prepolymer:

[0007] Mixing polyethylene glycol 200 and a plant antibacterial extract, adjusting the pH value to 4.5-6 with acetic acid, heating and stirring to dissolve the polyethylene glycol 200 to obtain a mixed solution, and then subjecting the mixed solution to a first reaction with a portion of melamine to obtain a reaction mixture;

[0008] The pH value of the reaction mixture is adjusted to 7-7.5 with triethanolamine, another portion of melamine and formaldehyde is added, the pH value of the system is adjusted to 8.5-9 with triethanolamine, and a second reaction is performed to obtain a polyethylene glycol-modified melamine-formaldehyde prepolymer;

[0009] (2) Preparation of flavor emulsion:

[0010] The emulsifier, essence and water are mixed to obtain a mixed solution, and the mixed solution is then sheared and emulsified to obtain an essential oil emulsion;

[0011] (3) Preparation of microcapsules:

[0012] The polyethylene glycol-modified melamine-formaldehyde prepolymer and the essential oil emulsion are mixed, and then the pH value of the system is adjusted to 3.5-6.5 with citric acid and a third reaction is carried out.

[0013] Preferably, in step (1), the method further comprises preparing the plant antibacterial extract according to the following steps: mixing the plant with ethanol and performing multiple ultrasonic extractions, and centrifuging the extracts obtained by the multiple ultrasonic extractions to obtain the plant antibacterial extract, wherein the weight ratio of the plant to the ethanol is 1:15-30.

[0014] Preferably, the conditions of the multiple ultrasonic extractions include: a temperature of 40-50° C. and a time of 40-50 min.

[0015] Preferably, the multiple ultrasonic extractions are performed 1-4 times.

[0016] Preferably, the plant is selected from at least one of bamboo leaves, mugwort, juniper and aloe.

[0017] Preferably, the centrifugal conditions include: a rotation speed of 1800-2200 r / min and a time of 15-30 min.

[0018] Preferably, in step (1), the weight ratio of the polyethylene glycol 200, the plant antibacterial extract and the portion of melamine is (1-10):(5-50):1.

[0019] Preferably, in step (1), the conditions of the first reaction include: temperature of 50-100° C. and time of 40-100 min.

[0020] Preferably, in step (1), the weight ratio of the other part of melamine, formaldehyde and the part of melamine is (0.5-5):(0.5-5):1.

[0021] Preferably, in step (1), the conditions of the second reaction include: temperature of 50-100° C. and time of 20-60 min.

[0022] Preferably, in step (2), the weight ratio of the essence, the water and the emulsifier is (1-20):(1-30):1.

[0023] Preferably, the emulsifier is selected from at least one of sodium dodecylbenzenesulfonate, Tween 60 and Tween 80.

[0024] Preferably, the fragrance is selected from at least one of peach essential oil, wormwood essential oil, orange essential oil and rose essential oil.

[0025] Preferably, the shear emulsification conditions include: a rotation speed of 10000-14000 r / min and a time of 3-8 min.

[0026] Preferably, in step (3), the weight ratio of the polyethylene glycol-modified melamine-formaldehyde prepolymer to the essential oil emulsion is 3-10:1.

[0027] Preferably, the conditions of the third reaction include: temperature of 30-80° C. and time of 1-4 h.

[0028] The second aspect of the present invention provides an antibacterial microcapsule prepared by the method described above.

[0029] The third aspect of the present invention provides a use of the antibacterial microcapsule in preparing antibacterial fabrics.

[0030] The antibacterial microcapsules of the present invention use melamine-formaldehyde resin modified by polyethylene glycol as the microcapsule shell, which can improve the heat resistance of the antibacterial microcapsules, prevent the shell from decomposing under high temperature environment, and destroy the slow-release function of the antibacterial microcapsules for antibacterial components and aromatic components. The shell of the antibacterial microcapsules has antibacterial components, and the capsule core has aromatic components, which can quickly and efficiently remove harmful microorganisms on fabrics, while retaining the aromatic smell of the fabrics for a long time. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 is a SEM picture of the antibacterial microcapsule A1 prepared in Example. DETAILED DESCRIPTION

[0032] The specific embodiments of the present invention are described in detail below. It should be understood that the specific embodiments described herein are only used to illustrate and explain the present invention, and are not used to limit the present invention.

[0033] The endpoints and any values ​​of the ranges disclosed in this article are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of each range, the endpoint values ​​of each range and the individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed in this article.

[0034] The method for preparing the antibacterial microcapsules of the present invention comprises the following steps:

[0035] (1) Preparation of polyethylene glycol modified melamine-formaldehyde prepolymer:

[0036] Mixing polyethylene glycol 200 and a plant antibacterial extract, adjusting the pH value to 4.5-6 with acetic acid, heating and stirring to dissolve the polyethylene glycol 200 to obtain a mixed solution, and then subjecting the mixed solution to a first reaction with a portion of melamine to obtain a reaction mixture;

[0037] The pH value of the reaction mixture is adjusted to 7-7.5 with triethanolamine, another portion of melamine and formaldehyde is added, the pH value of the system is adjusted to 8.5-9 with triethanolamine, and a second reaction is performed to obtain a polyethylene glycol-modified melamine-formaldehyde prepolymer;

[0038] (2) Preparation of flavor emulsion:

[0039] The emulsifier, essence and water are mixed to obtain a mixed solution, and the mixed solution is then sheared and emulsified to obtain an essential oil emulsion;

[0040] (3) Preparation of microcapsules:

[0041] The polyethylene glycol-modified melamine-formaldehyde prepolymer and the essential oil emulsion are mixed, and then the pH value of the system is adjusted to 3.5-6.5 with citric acid and a third reaction is carried out.

[0042] In the method described in the present invention, in step (1), the method also includes preparing a plant antibacterial extract according to the following steps: mixing the plant with ethanol and performing multiple ultrasonic extractions, and centrifuging the extract obtained by the multiple ultrasonic extractions to obtain the plant antibacterial extract, wherein the weight ratio of the plant to the ethanol is 1:15-30, preferably 1:15-25.

[0043] In some embodiments, the conditions of the multiple ultrasonic extractions may include: a temperature of 40-50° C., preferably 45° C.; a time of 40-50 min, preferably 45 min. In these embodiments, when the conditions of the multiple ultrasonic extractions are within the above range (especially within the preferred range), the efficiency of the multiple ultrasonic extractions is higher.

[0044] In a more preferred embodiment, the number of the multiple ultrasonic extractions can be 1-4 times, more preferably 1-2 times. In these embodiments, when the number of the multiple ultrasonic extractions is within the above range (especially within the preferred range), the multiple ultrasonic extractions are more efficient.

[0045] In a more preferred embodiment, the plant can be at least one of zongzi leaves, mugwort, juniper and aloe, and is further preferably zongzi leaves. In these preferred embodiments, when the species of the plant is within the above range, the plant antibacterial liquid has a better antibacterial effect.

[0046] In some embodiments, the centrifugal conditions may include: a rotation speed of 1800-2200 r / min, preferably 1900-2100 r / min; a time of 15-30 min, preferably 20-25 min. In these embodiments, when the centrifugal conditions are within the above range (especially within the preferred range), the effect of solid-liquid separation of the extract is better.

[0047] In the method of the present invention, in step (1), the mixing is carried out under stirring conditions, and the mixing conditions may include: a temperature of 40-80°C, preferably 50-70°C; and a time of 20-50 min, preferably 30-40 min.

[0048] In the present invention, in step (1), the acetic acid can be used in the form of an aqueous solution. In a preferred embodiment, the concentration of the acetic acid aqueous solution can be 10-30% by weight, more preferably 10-15% by weight.

[0049] In the present invention, in step (1), the formaldehyde can be used in the form of an aqueous solution. In a preferred embodiment, the concentration of the formaldehyde aqueous solution can be 30-50% by weight, more preferably 30-40% by weight.

[0050] In the method of the present invention, in step (1), the weight ratio of the polyethylene glycol 200, the plant antibacterial extract and the portion of melamine can be (1-10): (5-50): 1, preferably (1-4): (20-50): 1. In the present invention, when the weight ratios of the polyethylene glycol 200, the plant antibacterial extract and the portion of melamine are within the above range (especially within the preferred range), the polyethylene glycol has a better modification effect on the melamine.

[0051] In the method of the present invention, in step (1), the conditions of the first reaction may include: a temperature of 50-100° C., preferably 70-80° C.; and a time of 40-100 min, preferably 40-60 min.

[0052] In the present invention, when the first reaction condition is within the above range (especially within the preferred range), the polyethylene glycol has a better modification effect on the melamine.

[0053] In the method of the present invention, in step (1), the weight ratio of the other part of melamine, formaldehyde and the part of melamine can be (0.5-5): (0.5-5): 1, preferably (1-3): (1-3): 1. In the present invention, when the weight ratio of the other part of melamine, formaldehyde and the part of melamine is within the above range (especially within the preferred range), the polyethylene glycol-modified melamine-formaldehyde prepolymer prepared by the method of the present invention has better thermal stability.

[0054] In the method of the present invention, in step (1), the conditions of the second reaction may include: a temperature of 50-100°C, preferably 70-80°C; a time of 20-60 min, preferably 30-50 min. In the present invention, when the conditions of the second reaction are within the above range (especially within the preferred range), the polyethylene glycol-modified melamine-formaldehyde prepolymer prepared by the method of the present invention has better thermal stability.

[0055] In the method of the present invention, in step (2), the weight ratio of the essence, the water and the emulsifier can be (1-20): (1-30): 1, preferably (1-15): (1-25): 1. In the present invention, when the weight ratio of the essence, the water and the emulsifier is within the above range (especially within the preferred range), the emulsification effect and dispersion degree of the essential oil emulsion are better.

[0056] In the present invention, the emulsifier may be at least one of sodium dodecylbenzenesulfonate, Tween 60 and Tween 80, preferably sodium dodecylbenzenesulfonate.

[0057] In the present invention, the essence can be at least one of peach essential oil, wormwood essential oil, orange essential oil and rose essential oil, preferably wormwood essential oil.

[0058] In the method of the present invention, the shear emulsification conditions may include: a rotation speed of 10000-14000 r / min, preferably 11000-13000 r / min; a time of 3-8 min, preferably 4-6 min. In the present invention, when the shear emulsification conditions are within the above range (especially within the preferred range), the emulsification effect and dispersion degree of the essential oil emulsion are better.

[0059] In the method of the present invention, in step (3), the mixing process further comprises: adding the essential oil emulsion dropwise into the polyethylene glycol-modified melamine-formaldehyde prepolymer solution, wherein the dropping speed may be 1-4 drops / s, preferably 1-2 drops / s.

[0060] In the present invention, in step (3), the citric acid can be used in the form of an aqueous solution. In a preferred embodiment, the concentration of the citric acid aqueous solution can be 10-30% by weight, more preferably 10-15% by weight.

[0061] In the method of the present invention, in step (3), the weight ratio of the polyethylene glycol-modified melamine-formaldehyde prepolymer to the essential oil emulsion can be 3-10:1, preferably 5-10:1. In the present invention, when the weight ratio of the polyethylene glycol-modified melamine-formaldehyde prepolymer to the essential oil emulsion is within the above range (especially within the preferred range), the antibacterial microcapsule has a more stable core-shell structure and a better antibacterial effect.

[0062] In the method of the present invention, the conditions of the third reaction may include: a temperature of 30-80°C, preferably 40-60°C; a time of 1-4h, preferably 1-3h. In the present invention, when the conditions of the third reaction are within the above range (especially within the preferred range), the antibacterial microcapsules have a more stable core-shell structure and a better antibacterial effect.

[0063] like Figure 1As shown, the antibacterial microcapsules prepared by the method described above are in the shape of regular spheres, and the antibacterial microcapsules have a core-shell structure, the shell of which is melamine-formaldehyde resin modified by polyethylene glycol, and the capsule core is aromatic essential oil, wherein the melamine-formaldehyde resin shell modified by polyethylene glycol has good heat resistance, which prevents the antibacterial microcapsules from decomposing in a high temperature environment and destroying their sustained release function for antibacterial components and aromatic components. The shell of the antibacterial microcapsules has antibacterial components, and the capsule core has aromatic components, which can quickly and efficiently remove harmful bacteria on fabrics, while retaining the aromatic smell of the fabrics for a long time.

[0064] In the application of the present invention, the antibacterial microcapsules, adhesive and water are mixed to obtain a mixed coating, which is applied to the surface of the fabric by padding or scraping, and then dried at 40-160° C. for 2-6 minutes to obtain the antibacterial fabric.

[0065] The antibacterial microcapsules and their preparation methods and applications of the present invention are further described below by way of examples. The examples are implemented based on the technical solution of the present invention, and detailed implementation methods and specific operation processes are given, but the protection scope of the present invention is not limited to the following examples.

[0066] The experimental methods in the following examples, unless otherwise specified, are all conventional methods in the art. The experimental materials used in the following examples, unless otherwise specified, are all commercially available.

[0067] Example 1

[0068] (1) Weighing 10 g of dried mugwort powder and placing it in a conical flask, adding ethanol to the conical flask in a weight ratio of 1:15 and mixing evenly, ultrasonically extracting the mugwort powder with the ethanol at 45° C. for 40 min, filtering the obtained solid-liquid mixture to obtain a filtrate and a filter residue, centrifuging the filtrate at room temperature for 20 min (speed of 2000 r / min), collecting the supernatant, and obtaining a mugwort extract;

[0069] (2) 0.8 g of polyethylene glycol 200 and 40 mL of the mugwort extract were added to a 250 mL round-bottom flask, and after mixing evenly, the pH value of the mixed solution was adjusted to 6.0 with 10% by weight acetic acid, and then the mixed solution was heated to 55° C. and stirred at a constant temperature for 30 min to dissolve the polyethylene glycol 200 evenly, and then 0.8 g of melamine was slowly added to the round-bottom flask, and the mixture was reacted at 90° C. under magnetic stirring for 70 min to obtain a polyethylene glycol-modified melamine solution, wherein the polyethylene glycol 200 and the mugwort extract were mixed evenly. The weight ratio of the extract to the melamine is 1:50:1; then the polyethylene glycol-modified melamine solution is cooled to 75°C, and its pH value is adjusted to 7 with triethanolamine at 75°C, and then 4g of formaldehyde and 4g of melamine are added to the round-bottom flask, and after uniform mixing, the pH value of the obtained mixed system is adjusted to 9.0 with triethanolamine, and the obtained mixed system is reacted at 75°C under magnetic stirring for 30 minutes to obtain a polyethylene glycol-modified melamine-formaldehyde prepolymer, wherein the weight ratio of the formaldehyde to the melamine is 1:1;

[0070] (3) 15 g of lavender essential oil, 4 g of Tween-80 and 81 g of deionized water are uniformly mixed to obtain a mixed solution, and the mixed solution is sheared and emulsified by a high-speed shear emulsifier at 12000 r / min to obtain an essential oil emulsion after 5 minutes, wherein the weight ratio of the lavender essential oil, the deionized water and the Tween-80 is 3.75:20.25:1;

[0071] (4) 20 g of the essential oil emulsion was added dropwise into 100 g of the polyethylene glycol-modified melamine-formaldehyde prepolymer at a rate of 2 drops / s. After mixing evenly, the pH value of the system was adjusted to 6.0 using a 10 wt % citric acid solution, and the mixture was reacted at 50° C. for 2 h to obtain lavender antibacterial microcapsules A1, wherein the weight ratio of the polyethylene glycol-modified melamine-formaldehyde prepolymer to the essential oil emulsion was 5:1.

[0072] Example 2

[0073] (1) Weighing 15 g of dried zongzi leaf powder and placing it in a conical flask, adding ethanol to the conical flask in a weight ratio of 1:25 and mixing them evenly, ultrasonically extracting the zongzi leaf powder using the ethanol at 45° C. for 45 min, filtering the obtained solid-liquid mixture to obtain a filtrate and a filter residue, centrifuging the filtrate at room temperature for 20 min (speed of 2000 r / min), collecting the supernatant, and obtaining a zongzi leaf extract;

[0074] (2) 1 g of polyethylene glycol 200 and 20 mL of the rice dumpling leaf extract were added to a 250 mL round-bottom flask, and after mixing evenly, the pH value of the mixed solution was adjusted to 5.0 with 10% by weight acetic acid, and then the mixed solution was heated to 60° C. and stirred at a constant temperature for 35 min to dissolve the polyethylene glycol 200 evenly, and then 1 g of melamine was slowly added to the round-bottom flask, and the mixture was reacted at 90° C. under magnetic stirring for 70 min to obtain a polyethylene glycol-modified melamine solution, wherein the polyethylene glycol 200 and the mugwort extract were The weight ratio of the polyethylene glycol-modified melamine solution to the melamine is 1:20:1; then the polyethylene glycol-modified melamine solution is cooled to 75°C, and its pH value is adjusted to 7 with triethanolamine at 75°C, and then 1g of formaldehyde and 1g of melamine are added to the round-bottom flask, and after mixing evenly, the pH value of the obtained mixed system is adjusted to 8.5 with triethanolamine, and the obtained mixed system is reacted at 80°C under magnetic stirring for 30 minutes to obtain a polyethylene glycol-modified melamine-formaldehyde prepolymer, wherein the weight ratio of the formaldehyde to the melamine is 1:1;

[0075] (3) 2 g of sodium dodecylbenzene sulfonate and 8 g of deionized water were mixed, and 15 g of peach essential oil was added to obtain a mixed solution. The mixed solution was sheared and emulsified by a high-speed shear emulsifier at 12000 r / min to obtain an essential oil emulsion after 5 min, wherein the weight ratio of the peach essential oil, the water and the sodium dodecylbenzene sulfonate was 7.5:4:1;

[0076] (4) 10 g of the essential oil emulsion was added dropwise into 100 g of the polyethylene glycol-modified melamine-formaldehyde prepolymer at a rate of 1 drop / s. After mixing evenly, the pH value of the system was adjusted to 7.0 using a 10 wt % citric acid solution, and the mixture was reacted at 50° C. for 2 h to obtain peach antibacterial microcapsules A2, wherein the weight ratio of the polyethylene glycol-modified melamine-formaldehyde prepolymer to the essential oil emulsion was 10:1.

[0077] Example 3

[0078] (1) Weighing 25 g of dried zongzi leaf powder and placing it in a conical flask, adding ethanol to the conical flask in a weight ratio of 1:25 and mixing them evenly, ultrasonically extracting the zongzi leaf powder using the ethanol at 45° C. for 45 min, filtering the obtained solid-liquid mixture to obtain a filtrate and a filter residue, centrifuging the filtrate at room temperature for 20 min (speed of 2000 r / min), collecting the supernatant, and obtaining a zongzi leaf extract;

[0079] (2) 1.2 g of polyethylene glycol 200 and 30 mL of the rice dumpling leaf extract were added to a 250 mL round-bottom flask, and after uniform mixing, the pH value of the mixed solution was adjusted to 6.0 with 10 wt % acetic acid, and then the mixed solution was heated to 70° C. and stirred at a constant temperature for 40 min to dissolve the polyethylene glycol 200 uniformly, and then 1.2 g of melamine was slowly added to the round-bottom flask, and the mixture was reacted at 90° C. under magnetic stirring for 70 min to obtain a polyethylene glycol-modified melamine solution, wherein the polyethylene glycol 200, the mugwort extract and The weight ratio of the melamine used is 1:25:1; then the polyethylene glycol-modified melamine solution is cooled to 75°C, and its pH value is adjusted to 8.5 with triethanolamine at 75°C, and then 1.2g of formaldehyde and 2.4g of melamine are added to the round-bottom flask, and after mixing evenly, the pH value of the obtained mixed system is adjusted to 8.5 with triethanolamine, and the obtained mixed system is reacted at 75°C under magnetic stirring for 30 minutes to obtain a polyethylene glycol-modified melamine-formaldehyde prepolymer, wherein the weight ratio of the formaldehyde to the melamine used is 0.5:1;

[0080] (3) 0.5 g of sodium dodecylbenzene sulfonate and 6.5 g of deionized water are mixed, and 5 g of lavender essential oil is added to obtain a mixed solution. The mixed solution is sheared and emulsified by a high-speed shear emulsifier at 12000 r / min to obtain an essential oil emulsion after 5 minutes, wherein the weight ratio of the lavender essential oil, the water and the sodium dodecylbenzene sulfonate is 10:13:1;

[0081] (4) 12.5 g of the essential oil emulsion was added dropwise into 100 g of the polyethylene glycol-modified melamine-formaldehyde prepolymer at a rate of 2 drops / s. After mixing evenly, the pH value of the system was adjusted to 5.0 using a 10 wt % citric acid solution, and the mixture was reacted at 50° C. for 2 h to obtain peach antibacterial microcapsules A3, wherein the weight ratio of the polyethylene glycol-modified melamine-formaldehyde prepolymer to the essential oil emulsion was 8:1.

[0082] Comparative Example 1

[0083] (1) weighing 7.5 g of chitosan, adding 506 mL of deionized water, heating to 90° C. under stirring to obtain a chitosan solution, then dropping 1 mL of dihydrate acetic acid into the chitosan solution to adjust the pH value to 5.5, reacting at 90° C. under stirring for 1 h, then cooling the resulting product to 60° C. and reacting at a constant temperature for 8 h, filtering the reaction product to obtain a transparent microcapsule wall material hydrosol;

[0084] (2) Weigh 80 g of lavender essential oil, 15 g of polyhexamethylene biguanide hydrochloride, 30 g of oxyethylene sorbitan monooleate, 3 g of glycerol, 6 g of polyethylene glycol 400, and 220 g of benzyl benzoate, heat and dissolve until the temperature rises to 60° C. and then keep the temperature constant for 10 min, add 150 mL of an aqueous solution containing 1% anionic sodium lauryl sulfate, and treat with a high-speed shear emulsifier for 10 min to obtain a microcapsule core material emulsion;

[0085] (3) 506 mL of a chitosan aqueous solution at a temperature of 55° C. was added to the microcapsule core material emulsion to obtain a mixed solution, and the mixed solution was stirred with a stirrer at 55° C. and 800 r / min for 30 min, and then the stirring speed was reduced to 210 r / min for reaction. After 8 h, the stirring was stopped and the reaction product was naturally cooled to room temperature to obtain microcapsules of lavender essential oil and polyhexamethylene biguanide hydrochloride, which were calculated as D1.

[0086] Comparative Example 2

[0087] This comparative example is implemented according to the method of Example 1, except that the process of step (2) further includes:

[0088] 0.8 g of polyethylene glycol 200 and 40 mL of the mugwort extract were added to a 250 mL round-bottom flask, and after mixing evenly, the pH value of the mixed solution was adjusted to 3.0 with 10% by weight acetic acid, and then the mixed solution was heated to 55° C. and stirred at a constant temperature for 30 minutes to dissolve the polyethylene glycol 200 evenly, and then 0.8 g of melamine was slowly added to the round-bottom flask, and the mixture was reacted at 90° C. under magnetic stirring for 70 minutes to obtain a polyethylene glycol-modified melamine solution, wherein the polyethylene glycol 200 and the mugwort extract were mixed evenly. The weight ratio of the liquid to the melamine is 1:50:1; then the polyethylene glycol-modified melamine solution is cooled to 75°C, and its pH value is adjusted to 6 with triethanolamine at 75°C, and then 4g of formaldehyde and 4g of melamine are added to the round-bottom flask, and after mixing evenly, the pH value of the obtained mixed system is adjusted to 7.0 with triethanolamine, and the obtained mixed system is reacted at 75°C under magnetic stirring for 30 minutes to obtain a polyethylene glycol-modified melamine-formaldehyde prepolymer, wherein the weight ratio of the formaldehyde to the melamine is 1:1;

[0089] The antibacterial microcapsules prepared in this comparative example are designated as D2.

[0090] Comparative Example 3

[0091] This comparative example is implemented according to the method of Example 1, except that the process of step (2) further includes:

[0092] 0.8 g of polyethylene glycol 200 and 40 mL of the mugwort extract were added to a 250 mL round-bottom flask, and after mixing evenly, the pH value of the mixed solution was adjusted to 6.5 with 10% by weight acetic acid, and then the mixed solution was heated to 55° C. and stirred at a constant temperature for 30 minutes to dissolve the polyethylene glycol 200 evenly, and then 0.8 g of melamine was slowly added to the round-bottom flask, and the mixture was reacted at 90° C. under magnetic stirring for 70 minutes to obtain a polyethylene glycol-modified melamine solution, wherein the polyethylene glycol 200 and the mugwort extract were mixed evenly. The weight ratio of the liquid to the melamine is 1:50:1; then the polyethylene glycol-modified melamine solution is cooled to 75°C, the pH value thereof is adjusted to 8 with triethanolamine at 75°C, 4g of formaldehyde and 4g of melamine are added to the round-bottom flask, the mixture is evenly mixed, and the pH value of the obtained mixed system is adjusted to 9.5 with triethanolamine, and the obtained mixed system is reacted at 75°C under magnetic stirring for 30 minutes to obtain a polyethylene glycol-modified melamine-formaldehyde prepolymer, wherein the weight ratio of the formaldehyde to the melamine is 1:1.

[0093] The antibacterial microcapsules prepared in this comparative example are designated as D3.

[0094] Comparative Example 4

[0095] This comparative example was implemented according to the method of Example 1, except that in step (3), a 10 wt % citric acid solution was used to adjust the pH value of the obtained mixed system to 7.5.

[0096] The antibacterial microcapsules prepared in this comparative example are designated as D4.

[0097] Comparative Example 5

[0098] This comparative example was implemented according to the method of Example 1, except that in step (3), a 10 wt % citric acid solution was used to adjust the pH value of the obtained mixed system to 3.0.

[0099] The antibacterial microcapsules prepared in this comparative example are designated as D5.

[0100] Test Case

[0101] Take 2 g of each of the antibacterial microcapsules A1-A3 and D1-D5 prepared in Examples 1-3 and Comparative Examples 1-5, heat to 170°C and keep constant temperature for 3 minutes, then cool naturally, then mix the 2 g of antibacterial microcapsules A1-A3 and D1-D5 with 98 g of water and stir evenly to obtain 8 parts of antibacterial microcapsule mixed liquid, then use the 8 parts of antibacterial microcapsule mixed liquid to pad cotton fabrics, and after padding, dry the fabrics at 80°C;

[0102] The colony counts of Escherichia coli and Staphylococcus aureus on the surfaces of cotton fabrics padded with the mixed solution of the antibacterial microcapsules A1-A3 and D1-D5 and cotton fabrics not padded were detected respectively, and the antibacterial rates of the antibacterial microcapsules A1-A3 and D1-D5 were calculated.

[0103] Table 1

[0104]

[0105]

[0106] It can be seen from the results in Table 1 that, compared with the commercially available antibacterial microcapsules D1, the antibacterial microcapsules A1-A3 of the present invention prepared in Examples 1-3 still have good antibacterial effects after high-temperature treatment at 170°C, indicating that they have good thermal stability; while the antibacterial microcapsules D2-D5 prepared in Comparative Examples 2-5 have poor core-shell structures of the prepared antibacterial microcapsules due to the fact that the pH value of the reactant system is too high or too low during the preparation process, and the antibacterial components cannot be effectively released, and thus their antibacterial effects are far inferior to the antibacterial microcapsules A1-A3 prepared in Examples 1-3.

[0107] The preferred embodiments of the present invention are described in detail above, but the present invention is not limited thereto. Within the technical concept of the present invention, the technical solution of the present invention can be subjected to a variety of simple modifications, including the combination of various technical features in any other suitable manner, and these simple modifications and combinations should also be regarded as the contents disclosed by the present invention and belong to the protection scope of the present invention.

Claims

1. A method for preparing antibacterial microcapsules, characterized in that: The method comprises the following steps: (1) Preparation of polyethylene glycol modified melamine-formaldehyde prepolymer: Mixing polyethylene glycol 200 and a plant antibacterial extract, adjusting the pH value to 4.5-6 with acetic acid, heating and stirring to dissolve the polyethylene glycol 200 to obtain a mixed solution, and then subjecting the mixed solution to a first reaction with a portion of melamine to obtain a reaction mixture; The pH value of the reaction mixture is adjusted to 7-7.5 with triethanolamine, another portion of melamine and formaldehyde is added, the pH value of the system is adjusted to 8.5-9 with triethanolamine, and a second reaction is performed to obtain a polyethylene glycol-modified melamine-formaldehyde prepolymer; (2) Preparation of flavor emulsion: The emulsifier, essence and water are mixed to obtain a mixed solution, and the mixed solution is then sheared and emulsified to obtain an essential oil emulsion; (3) Preparation of microcapsules: The polyethylene glycol-modified melamine-formaldehyde prepolymer and the essential oil emulsion are mixed, and then the pH value of the system is adjusted to 3.5-6.5 with citric acid and a third reaction is carried out.

2. The preparation method according to claim 1, characterized in that: In step (1), the method further comprises preparing the plant antibacterial extract according to the following steps: mixing the plant with ethanol and performing ultrasonic extraction multiple times, centrifuging the extract obtained by the ultrasonic extraction multiple times to obtain the plant antibacterial extract, wherein the weight ratio of the plant to the ethanol is 1:15-30; Preferably, the conditions of the multiple ultrasonic extractions include: a temperature of 40-50°C and a time of 40-50 min; Preferably, the number of multiple ultrasonic extractions is 1-4 times; Preferably, the plant is selected from at least one of bamboo leaves, mugwort, juniper and aloe; Preferably, the centrifugal conditions include: a rotation speed of 1800-2200 r / min and a time of 15-30 min.

3. The preparation method according to claim 1 or 2, characterized in that: In step (1), the weight ratio of the polyethylene glycol 200, the plant antibacterial extract and the portion of melamine is (1-10):(5-50):

1.

4. The preparation method according to claim 1, characterized in that: In step (1), the conditions of the first reaction include: temperature of 50-100° C. and time of 40-100 min.

5. The preparation method according to claim 1, characterized in that: In step (1), the weight ratio of the other part of melamine, formaldehyde and the part of melamine is (0.5-5):(0.5-5):

1.

6. The preparation method according to claim 1, characterized in that: In step (1), the conditions of the second reaction include: temperature of 50-100° C. and time of 20-60 min.

7. The preparation method according to claim 1, characterized in that: In step (2), the weight ratio of the essence, the water and the emulsifier is (1-20): (1-30): 1; Preferably, the emulsifier is selected from at least one of sodium dodecylbenzenesulfonate, Tween 60 and Tween 80; Preferably, the fragrance is selected from at least one of peach essential oil, wormwood essential oil, orange essential oil and rose essential oil; Preferably, the shear emulsification conditions include: a rotation speed of 10000-14000 r / min and a time of 3-8 min.

8. The preparation method according to claim 1, characterized in that: In step (3), the weight ratio of the polyethylene glycol-modified melamine-formaldehyde prepolymer to the essential oil emulsion is 3-10:1; Preferably, the conditions of the third reaction include: temperature of 30-80° C. and time of 1-4 h.

9. Antibacterial microcapsules prepared by the method according to any one of claims 1 to 8.

10. Use of the antibacterial microcapsule according to claim 9 in preparing antibacterial fabrics.

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