A kind of polyethylene garbage bag with fragrance and preparation method thereof

Abstract

The invention relates to the field of plastics, in particular to a scented polyethylene garbage bag and a preparation method thereof. The composite silica aerogel microcapsules use porous silica aerogel as a carrier of natural plant essential oil to prepare silica aerogel microcapsules, load a polydopamine outer layer on the surface of the microcapsules through oxidative self-polymerization of dopamine, and then graft composite quaternized polyethyleneimine on the surface; bio-based diols are obtained by reacting bio-vanillin and cystamine dihydrochloride, and then the bio-based diols are synthesized with natural castor oil and isophorone diisocyanate under the action of a catalyst to synthesize a prepolymer, use 2,2-dihydroxymethylbutyric acid as a hydrophilic chain extender, use 4-amino-3-methylphenol with a rigid hydrophobic benzene ring structure and antibacterial phenolic hydroxyl groups as a capping agent, and use composite quaternized polyethyleneimine as a crosslinking agent to synthesize a modified bio-based polyurethane emulsion.

Description

Technical Field

[0001] The invention relates to the field of plastics, in particular to a scented polyethylene garbage bag and a preparation method thereof. Background Art

[0002] A huge amount of plastic bags are consumed every year in the world. As people's quality of life improves, people have a higher demand for plastic bags. Plastic bags can be divided into packaging bags, shopping bags, garbage bags, etc. According to their uses, plastic bags on the market are generally odorless. When they are used to store daily necessities garbage or kitchen waste, especially in the hot summer, the garbage is easy to rot and emit odor. Plastic bags without fragrance cannot cover up the unpleasant smell caused by the corruption of garbage.

[0003] At present, flavors are usually added to plastic products in the market to make garbage bags have fragrance. However, there are also problems such as the high processing temperature causing the flavor to volatilize, the fragrance is not pure and not lasting; and the rotting of garbage will cause bacteria to grow, so the existing market also has a certain demand for the antibacterial properties of garbage bags. Summary of the invention

[0004] The object of the present invention is to provide a scented polyethylene garbage bag and a preparation method thereof, so as to solve the problems in the prior art.

[0005] In order to solve the above technical problems, the present invention provides the following technical solutions:

[0006] A method for preparing a scented polyethylene garbage bag comprises the following steps:

[0007] S1: Mixing HDPE granules, LDPE granules, LLDPE granules, calcium carbonate and plastic color species, extruding, blowing films, and cooling to obtain a substrate;

[0008] S2: Preparation of protective coatings using modified bio-based polyurethane emulsion and composite silica aerogel microcapsules;

[0009] S3: coating the protective coating on the surface of the substrate and curing the coating to obtain a scented polyethylene garbage bag.

[0010] Furthermore, the composition of the base material is, by weight: 40-60 parts of HDPE particles, 3-7 parts of LDPE particles, 19-25 parts of LLDPE particles, 20-22 parts of calcium carbonate, and 1-3 parts of plastic color.

[0011] Furthermore, the blow ratio of the blown film is 2-3.

[0012] Furthermore, the mass ratio of the modified bio-based polyurethane emulsion to the composite silica aerogel microcapsules in the protective coating is 47:(6-8).

[0013] Further, the preparation of composite silica aerogel microcapsules includes the following steps:

[0014] (1) Mix silica aerogel and plant essential oil, ultrasonically disperse for 10-20 minutes, move to a vacuum environment, add deionized water, stir for 3-5 hours at 18-25°C, take out, centrifuge, wash, and dry to obtain silica aerogel microcapsules;

[0015] (2) Mix silica aerogel microcapsules and deionized water, add dopamine hydrochloride, stir for 3-5 minutes, add tris(hydroxymethyl)aminomethane, heat to 28-32°C and stir for 22-24 hours in the dark, centrifuge, wash with water, and dry to obtain modified silica aerogel microcapsules;

[0016] (3) The modified silica aerogel microcapsules and Tris buffer solution are mixed, and composite quaternized polyethyleneimine is added. The mixture is shaken at 18-25° C. for 22-24 hours, centrifuged, washed, and dried to obtain composite silica aerogel microcapsules.

[0017] Further, the preparation of the modified bio-based polyurethane emulsion comprises the following steps:

[0018] 1) Mix vanillin, cystamine dihydrochloride and methanol under nitrogen atmosphere, keep warm at 62-68°C for 10-12h, evaporating, adding ethyl acetate, centrifuging, drying, adding ethanol, centrifuging, drying to obtain bio-based diol;

[0019] 2) Under the protection of nitrogen, castor oil and bio-based diol are mixed, the temperature is raised to 76-80°C, isophorone diisocyanate and dibutyltin dilaurate are added, and the temperature is kept for 2-3 hours. 2,2-dihydroxymethylbutyric acid and N,N-dimethylformamide are added, and the temperature is kept for 1-2 hours. The mixture is cooled to 18-25°C, 4-amino-3-methylphenol is added, and the temperature is kept for 1-2 hours. Triethylamine is added and the temperature is kept for 10-20 minutes. Composite quaternized polyethyleneimine is added and stirred for 1-2 hours. Deionized water is added and the mixture is emulsified for 1-2 hours. The mixture is rotary evaporated to obtain a modified bio-based polyurethane emulsion.

[0020] Furthermore, the plant essential oil is one of lavender oil, peppermint essential oil, clove essential oil, lemon essential oil, and rose essential oil, or a combination thereof.

[0021] Furthermore, the mass ratio of castor oil, bio-based diol, isophorone diisocyanate, 4-amino-3-methylphenol, and composite quaternized polyethyleneimine is 5:8:16:2:3.

[0022] Further, the preparation of the composite quaternized polyethyleneimine comprises the following steps:

[0023] Mix polyethyleneimine, methanol and 2,3-epoxypropyltrimethylammonium chloride, adjust the pH to 7.9-8.1, add epoxy POSS, keep warm at 48-52°C for 1-2 hours, add deionized water, adjust the pH to 3.9-4.1, stir for 1-2 hours to obtain composite quaternized polyethyleneimine.

[0024] Beneficial effects of the present invention:

[0025] The invention provides a scented polyethylene garbage bag and a preparation method thereof, and the prepared polyethylene garbage bag has good sealing performance, water resistance, antibacterial properties and lasting fragrance.

[0026] In order to give polyethylene garbage bags a lasting, stable and pure fragrance, a protective coating with composite silica aerogel microcapsules was introduced on the surface of the substrate, wherein the composite silica aerogel microcapsules used porous silica aerogel as a carrier of natural plant essential oils, and the plant essential oils were loaded into the interior of the aerogel by vacuum impregnation to prepare silica aerogel microcapsules. In order to give the microcapsules sustained release performance, a polydopamine outer layer was loaded on the surface of the microcapsules by oxidative self-polymerization of dopamine to obtain modified silica aerogel microcapsules with self-healing properties. While maintaining high stability of natural essential oils, it achieves the effect of long-lasting fragrance release. In order to further improve its antibacterial properties and uniformity of dispersion in the coating, composite quaternized polyethyleneimine is grafted on the surface of modified silica aerogel microcapsules to make it synergistic with plant essential oils with antibacterial effects to achieve broad-spectrum antibacterial effects. The composite quaternized polyethyleneimine is modified by cationic etherifying agent 2,3-epoxypropyltrimethylammonium chloride and epoxy POSS on polyethyleneimine, which greatly improves the water resistance and antibacterial properties of polyethylene garbage bags, and effectively improves the mechanical properties and barrier properties of the protective coating.

[0027] In order to ensure that the protective coating on the polyethylene garbage bag can still maintain its long-term antibacterial and fragrance release capabilities when it encounters mechanical damage such as scratches, a protective coating with self-repairing properties after curing is coated on the surface of the substrate. The raw materials used for the existing aqueous polyurethanes are mainly derived from non-renewable petrochemical resources, and there are generally problems of poor water resistance and antibacterial properties. In response to the sustainable development strategy, the present invention uses bio-based raw materials vanillin and cystamine dihydrochloride to react to obtain bio-based diols, and then synthesizes prepolymers with natural castor oil and isophorone diisocyanate under the action of a catalyst, uses 2,2-dihydroxymethylbutyric acid as a hydrophilic chain extender, 4-amino-3-methylphenol with a rigid hydrophobic benzene ring structure and antibacterial phenolic hydroxyl groups as a capping agent, and composite quaternized polyethyleneimine as a cross-linking agent to synthesize a cross-linked network with multiple dynamic covalent bonds such as disulfide bonds, imine bonds and phenol-carbamate bonds, thereby increasing the complexity of the entanglement of the molecular chains, avoiding the precipitation of small molecules, obtaining a high-strength, antibacterial, self-repairing surface, and achieving the effects of long-term fragrance release, antibacterial, and sealing. DETAILED DESCRIPTION

[0028] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0029] It should be noted that if the embodiments of the present invention involve directional indications such as up, down, left, right, front, and back, the directional indication is only used to explain a specific posture such as the relative position relationship between the components, the movement status, etc. If the specific posture changes, the directional indication will also change accordingly. In addition, the technical solutions between the various embodiments can be combined with each other, but it must be based on the ability of ordinary technicians in this field to implement. When the combination of technical solutions is contradictory or cannot be implemented, it should be considered that such a combination of technical solutions does not exist and is not within the protection scope required by the present invention.

[0030] The technical solution of the present invention is further described in detail below in conjunction with specific embodiments. It should be understood that the following embodiments are only used to explain the present invention, and are not used to limit the present invention.

[0031] Embodiment 1: A method for preparing a scented polyethylene garbage bag, comprising the following steps:

[0032] S1: Mixing HDPE granules, LDPE granules, LLDPE granules, calcium carbonate and plastic color species, extruding, blowing films, and cooling to obtain a substrate;

[0033] The composition of the substrate is as follows, by mass: 40 parts of HDPE granules, 3 parts of LDPE granules, 19 parts of LLDPE granules, 20 parts of calcium carbonate, and 1 part of plastic color;

[0034] S2: Preparation of protective coatings using modified bio-based polyurethane emulsion and composite silica aerogel microcapsules;

[0035] The preparation of the composite silica aerogel microcapsules comprises the following steps:

[0036] (1) 0.5 g of silica aerogel and 5 g of plant essential oil were mixed, ultrasonically dispersed for 10 min, moved to a vacuum environment, 45 mL of deionized water was added, stirred at 18 ° C for 5 h, taken out, centrifuged, washed, and dried to obtain silica aerogel microcapsules;

[0037] (2) Mix 1 g of silica aerogel microcapsules and 40 mL of deionized water, add 0.2 g of dopamine hydrochloride, stir for 3 min, add 10 mg of tris(hydroxymethyl)aminomethane, heat to 28 °C and stir for 24 h in the dark, centrifuge, wash with water, and dry to obtain modified silica aerogel microcapsules;

[0038] (3) 1 g of modified silica aerogel microcapsules and 100 mL of Tris buffer solution with a pH of 8.5 were mixed, 2 g of composite quaternized polyethyleneimine was added, the mixture was shaken at 18 °C for 24 h, centrifuged, washed, and dried to obtain composite silica aerogel microcapsules;

[0039] The preparation of modified bio-based polyurethane emulsion comprises the following steps:

[0040] 1) Under nitrogen atmosphere, 2 g of vanillin, 1.5 g of cystamine dihydrochloride and 40 mL of methanol were mixed, kept at 62 °C for 12 h, rotary evaporated, 15 mL of ethyl acetate was added, centrifuged and dried, 15 mL of ethanol was added, centrifuged and dried to obtain bio-based diols;

[0041] 2) Under the protection of nitrogen, 5g of castor oil and 8g of bio-based diol were mixed, the temperature was raised to 76°C, 16g of isophorone diisocyanate and 2 drops of dibutyltin dilaurate were added, and the mixture was kept warm for 2h, 0.72g of 2,2-dihydroxymethylbutyric acid and 15mL of N,N-dimethylformamide were added, and the mixture was kept warm for 1h, the mixture was cooled to 18°C, 2g of 4-amino-3-methylphenol was added, and the mixture was kept warm for 1h, 0.2g of triethylamine was added, and the mixture was kept warm for 10min, 3g of composite quaternized polyethyleneimine was added, and the mixture was stirred for 1h, deionized water was added, and the mixture was emulsified for 1.5h, and the mixture was rotary evaporated to obtain a modified bio-based polyurethane emulsion with a solid content of 25%;

[0042] The preparation of composite quaternized polyethyleneimine comprises the following steps:

[0043] 2 g of polyethyleneimine, 30 mL of methanol, and 0.04 g of 2,3-epoxypropyltrimethylammonium chloride were mixed, the pH was adjusted to 7.9, 0.3 g of epoxy POSS was added, and the mixture was kept at 48°C for 2 h. 30 mL of deionized water was added, the pH was adjusted to 3.9, and the mixture was stirred for 1 h to obtain composite quaternized polyethyleneimine;

[0044] The mass ratio of modified bio-based polyurethane emulsion to composite silica aerogel microcapsules in the protective coating is 47:6;

[0045] S3: coating the protective coating on the surface of the substrate and curing the coating to obtain a scented polyethylene garbage bag.

[0046] Embodiment 2: A method for preparing a scented polyethylene garbage bag, comprising the following steps:

[0047] S1: Mixing HDPE granules, LDPE granules, LLDPE granules, calcium carbonate and plastic color species, extruding, blowing films, and cooling to obtain a substrate;

[0048] The composition of the substrate is as follows by weight: 50 parts of HDPE granules, 5 parts of LDPE granules, 21 parts of LLDPE granules, 21 parts of calcium carbonate, and 2 parts of plastic color;

[0049] S2: Preparation of protective coatings using modified bio-based polyurethane emulsion and composite silica aerogel microcapsules;

[0050] The preparation of the composite silica aerogel microcapsules comprises the following steps:

[0051] (1) 0.5 g of silica aerogel and 5 g of plant essential oil were mixed, ultrasonically dispersed for 15 min, moved to a vacuum environment, 45 mL of deionized water was added, stirred at 20 ° C for 4 h, taken out, centrifuged, washed, and dried to obtain silica aerogel microcapsules;

[0052] (2) 1 g of silica aerogel microcapsules and 40 mL of deionized water were mixed, 0.2 g of dopamine hydrochloride was added, and the mixture was stirred for 4 min. 10 mg of tris(hydroxymethyl)aminomethane was added, and the mixture was heated to 30 °C and stirred for 23 h in the dark. The mixture was centrifuged, washed with water, and dried to obtain modified silica aerogel microcapsules.

[0053] (3) 1 g of modified silica aerogel microcapsules and 100 mL of Tris buffer solution with a pH of 8.5 were mixed, 2 g of composite quaternized polyethyleneimine was added, the mixture was shaken at 20 °C for 23 h, centrifuged, washed, and dried to obtain composite silica aerogel microcapsules;

[0054] The preparation of modified bio-based polyurethane emulsion comprises the following steps:

[0055] 1) Under nitrogen atmosphere, 2 g of vanillin, 1.5 g of cystamine dihydrochloride and 40 mL of methanol were mixed, kept at 65 °C for 11 h, rotary evaporated, 15 mL of ethyl acetate was added, centrifuged and dried, 15 mL of ethanol was added, centrifuged and dried to obtain bio-based diols;

[0056] 2) Under the protection of nitrogen, 5g of castor oil and 8g of bio-based diol were mixed, the temperature was raised to 78°C, 16g of isophorone diisocyanate and 2 drops of dibutyltin dilaurate were added, and the temperature was kept for 2.5h, 0.72g of 2,2-dihydroxymethylbutyric acid and 15mL of N,N-dimethylformamide were added, and the temperature was kept for 1.5h, cooled to 20°C, 2g of 4-amino-3-methylphenol was added, and the temperature was kept for 1.5h, 0.2g of triethylamine was added, and the temperature was kept for 15min, 3g of composite quaternized polyethyleneimine was added, and stirred for 1.5h, deionized water was added for emulsification for 1.5h, and the modified bio-based polyurethane emulsion with a solid content of 25% was obtained;

[0057] The preparation of composite quaternized polyethyleneimine comprises the following steps:

[0058] 2 g of polyethyleneimine, 30 mL of methanol, and 0.04 g of 2,3-epoxypropyltrimethylammonium chloride were mixed, the pH was adjusted to 8.1, 0.3 g of epoxy POSS was added, and the mixture was kept at 52°C for 1 h. 30 mL of deionized water was added, the pH was adjusted to 4.1, and the mixture was stirred for 2 h to obtain composite quaternized polyethyleneimine;

[0059] The mass ratio of modified bio-based polyurethane emulsion to composite silica aerogel microcapsules in the protective coating is 47:7;

[0060] S3: coating the protective coating on the surface of the substrate and curing the coating to obtain a scented polyethylene garbage bag.

[0061] Embodiment 3: A method for preparing a scented polyethylene garbage bag, comprising the following steps:

[0062] S1: Mixing HDPE granules, LDPE granules, LLDPE granules, calcium carbonate and plastic color species, extruding, blowing films, and cooling to obtain a substrate;

[0063] The composition of the substrate is as follows by weight: 60 parts of HDPE granules, 7 parts of LDPE granules, 25 parts of LLDPE granules, 22 parts of calcium carbonate, and 3 parts of plastic color;

[0064] S2: Preparation of protective coatings using modified bio-based polyurethane emulsion and composite silica aerogel microcapsules;

[0065] The preparation of the composite silica aerogel microcapsules comprises the following steps:

[0066] (1) 0.5 g of silica aerogel and 5 g of plant essential oil were mixed, ultrasonically dispersed for 20 min, moved to a vacuum environment, 45 mL of deionized water was added, stirred at 25 ° C for 3, taken out, centrifuged, washed, and dried to obtain silica aerogel microcapsules;

[0067] (2) 1 g of silica aerogel microcapsules and 40 mL of deionized water were mixed, 0.2 g of dopamine hydrochloride was added, and the mixture was stirred for 5 min. 10 mg of tris(hydroxymethyl)aminomethane was added, and the mixture was heated to 32 °C and stirred for 22 h in the dark. The mixture was centrifuged, washed with water, and dried to obtain modified silica aerogel microcapsules.

[0068] (3) 1 g of modified silica aerogel microcapsules and 100 mL of Tris buffer solution with a pH of 8.5 were mixed, 2 g of composite quaternized polyethyleneimine was added, the mixture was shaken at 25 °C for 22 h, centrifuged, washed, and dried to obtain composite silica aerogel microcapsules;

[0069] The preparation of modified bio-based polyurethane emulsion comprises the following steps:

[0070] 1) Under nitrogen atmosphere, 2 g of vanillin, 1.5 g of cystamine dihydrochloride and 40 mL of methanol were mixed, kept at 68 °C for 10 h, rotary evaporated, 15 mL of ethyl acetate was added, centrifuged and dried, 15 mL of ethanol was added, centrifuged and dried to obtain bio-based diols;

[0071] 2) Under the protection of nitrogen, 5g of castor oil and 8g of bio-based diol were mixed, the temperature was raised to 80°C, 16g of isophorone diisocyanate and 2 drops of dibutyltin dilaurate were added, and the temperature was kept for 3h, 0.72g of 2,2-dihydroxymethylbutyric acid and 15mL of N,N-dimethylformamide were added, and the temperature was kept for 2h, the temperature was cooled to 25°C, 2g of 4-amino-3-methylphenol was added, and the temperature was kept for 2h, 0.2g of triethylamine was added, and the temperature was kept for 20min, 3g of composite quaternized polyethyleneimine was added, and stirred for 2h, deionized water was added for emulsification for 2h, and the modified bio-based polyurethane emulsion with a solid content of 25% was obtained;

[0072] The preparation of composite quaternized polyethyleneimine comprises the following steps:

[0073] 2 g of polyethyleneimine, 30 mL of methanol, and 0.04 g of 2,3-epoxypropyltrimethylammonium chloride were mixed, the pH was adjusted to 8.1, 0.3 g of epoxy POSS was added, and the mixture was kept at 52°C for 1 h. 30 mL of deionized water was added, the pH was adjusted to 4.1, and the mixture was stirred for 2 h to obtain composite quaternized polyethyleneimine;

[0074] The mass ratio of modified bio-based polyurethane emulsion to composite silica aerogel microcapsules in the protective coating is 47:8;

[0075] S3: coating the protective coating on the surface of the substrate and curing the coating to obtain a scented polyethylene garbage bag.

[0076] Comparative Example 1: Taking Example 3 as the control group, 4-amino-3-methylphenol was not added in the preparation of the modified bio-based polyurethane emulsion, and other processes were normal.

[0077] Comparative Example 2: Taking Example 3 as the control group, the composite silica aerogel microcapsules were replaced with silica aerogel microcapsules, and the other processes were normal.

[0078] Comparative Example 3: Example 3 was used as a control group, and composite quaternized polyethyleneimine was not prepared, and other processes were normal.

[0079] In the above-mentioned embodiments and comparative examples, the thickness of the substrate is 420 μm, and the thickness of the protective layer formed by the protective coating is 80 μm.

[0080] Sources of raw materials used (for demonstration purposes only):

[0081] HDPE granules F0554: Saudi Arabia Rabigh Petrochemical; LLDPE granules Q2018H, LDPE granules FD0474: Qatar Petrochemical; Plastic color 5320: Shenzhen Weichang Pigment Co., Ltd.; Silica aerogel 091458: Shanghai Koraman Reagent Co., Ltd.; Plant essential oil (lemon essential oil) 84929-31-7: Jishui Yikang Natural Fragrance Oil Refinery; Calcium carbonate C111980, dopamine hydrochloride D103111, tris (hydroxymethyl) aminomethane T110599, Tris buffer solution T475659, vanillin V100115 , cystamine dihydrochloride C424758, castor oil C110663, isophorone diisocyanate I109582, dibutyltin dilaurate D100274, 2,2-dihydroxymethylbutyric acid B115196, N,N-dimethylformamide D111999, 4-amino-3-methylphenol A121773, triethylamine T103285, polyethyleneimine E107079, 2,3-epoxypropyltrimethylammonium chloride G298766, epoxy POSSG140436: Aladdin reagent; methanol, ethanol, ethyl acetate, analytical grade: Sinopharm reagent.

[0082] Performance Test:

[0083] Water absorption rate: cut into a 20mm×20mm shape, soak in 25℃ deionized water for 24h, dry, and weigh its mass change, then water absorption rate = (m2-m1) / m1×100% (m1 represents the weight before soaking in water; m2 represents the weight after soaking); Antibacterial durability: refer to ISO22196:2007 for testing, use the plate counting method for testing, select ATCC6538 Staphylococcus aureus as the test strain, and test after 20 standard water washes; Self-healing property: scratch a 100µm long, 4µm wide, and 100µm deep scratch on the antibacterial plastic, keep it at 80℃ for 12h, and observe the scratch length with an electron microscope. The self-healing rate = (L0-L1) / L0×100% (L0 represents the initial scratch length; L1 represents the scratch length after heat treatment), the results are shown in Table 1;

[0084] Table 1

[0085]

[0086] The invention provides a scented polyethylene garbage bag and a preparation method thereof, and the prepared polyethylene garbage bag has good sealing performance, water resistance, antibacterial properties and lasting fragrance.

[0087] Example 3 is compared with Comparative Example 1 and Comparative Example 3. In order to make the protective coating on the polyethylene garbage bag still maintain its long-term antibacterial and fragrance release capabilities when encountering mechanical damage such as scratches, a protective coating with self-repairing properties after curing is coated on the surface of the substrate. The raw materials used in the existing aqueous polyurethane are mainly derived from non-renewable petrochemical resources, and there are generally problems of poor water resistance and antibacterial properties. In response to the sustainable development strategy, the present invention uses bio-vanillin and cystamine dihydrochloride to react to obtain bio-based diols, which are then reacted with natural castor oil to obtain bio-based diols. Sesame oil and isophorone diisocyanate are used to synthesize a prepolymer under the action of a catalyst, 2,2-dihydroxymethylbutyric acid is used as a hydrophilic chain extender, 4-amino-3-methylphenol with a rigid hydrophobic benzene ring structure and antibacterial phenolic hydroxyl group is used as a capping agent, and composite quaternized polyethyleneimine is used as a cross-linking agent to synthesize a cross-linked network with multiple dynamic covalent bonds such as disulfide bonds, imine bonds and phenol-urethane bonds, which increases the complexity of the entanglement of the molecular chains and avoids the precipitation of small molecules, thereby obtaining a high-strength, antibacterial, self-repairing surface and achieving long-lasting fragrance release, antibacterial and sealing effects.

[0088] Example 3 is compared with Comparative Examples 2 and 3. In order to give the polyethylene garbage bag a lasting, stable and pure fragrance, a protective coating with composite silica aerogel microcapsules is introduced on the surface of the substrate, wherein the composite silica aerogel microcapsules use porous silica aerogel as a carrier of natural plant essential oils, and the plant essential oils are loaded into the interior of the aerogel by vacuum impregnation to prepare silica aerogel microcapsules. In order to give the microcapsules a sustained release performance, a polydopamine outer layer is loaded on the surface of the microcapsules by oxidative self-polymerization of dopamine to obtain modified silica aerogel microcapsules with self-healing properties. While improving the stability of the natural essential oils, In order to achieve the effect of lasting fragrance release and further improve its antibacterial property and uniformity of dispersion in the coating, the Schiff base reaction is used to graft composite quaternized polyethyleneimine on the surface of the modified silica aerogel microcapsule, so that it can cooperate with plant essential oils with antibacterial effect to achieve a broad-spectrum antibacterial effect. The composite quaternized polyethyleneimine is prepared by modifying polyethyleneimine with cationic etherifying agent 2,3-epoxypropyltrimethylammonium chloride and epoxy POSS, introducing cationic groups and alkoxysilyl groups with high coupling activity into polyethyleneimine, and introducing them into the protective coating, which greatly improves the water resistance and antibacterial property of polyethylene garbage bags, and effectively improves the mechanical properties and barrier properties of the protective coating.

[0089] The above descriptions are only embodiments of the present invention and are not intended to limit the patent scope of the present invention. All equivalent structural changes made using the present invention specification under the inventive concept of the present invention, or direct / indirect applications in other related technical fields, are included in the patent protection scope of the present invention.

Claims

1. A method for preparing a scented polyethylene garbage bag, characterized in that: The following steps are involved: S1: Mixing HDPE granules, LDPE granules, LLDPE granules, calcium carbonate and plastic color species, extruding, blowing films, and cooling to obtain a substrate; S2: Preparation of protective coatings using modified bio-based polyurethane emulsion and composite silica aerogel microcapsules; S3: coating the protective coating on the surface of the substrate and curing the coating to obtain a scented polyethylene garbage bag; The preparation of the composite silica aerogel microcapsules comprises the following steps: (1) mixing silica aerogel and plant essential oil, ultrasonically dispersing for 10-20 minutes, moving to a vacuum environment, adding deionized water, stirring for 3-5 hours at 18-25° C., taking out, centrifuging, washing, and drying to obtain silica aerogel microcapsules; (2) mixing silica aerogel microcapsules and deionized water, adding dopamine hydrochloride, stirring for 3-5 minutes, adding tris(hydroxymethyl)aminomethane, heating to 28-32° C. and stirring for 22-24 hours in the dark, centrifuging, washing with water, and drying to obtain modified silica aerogel microcapsules; (3) mixing the modified silica aerogel microcapsules and Tris buffer solution, adding composite quaternized polyethyleneimine, shaking at 18-25° C. for 22-24 hours, centrifuging, washing, and drying to obtain composite silica aerogel microcapsules; The preparation of modified bio-based polyurethane emulsion comprises the following steps: 1) under a nitrogen atmosphere, vanillin, cystamine dihydrochloride and methanol are mixed, kept at 62-68° C. for 10-12 hours, rotary evaporated, ethyl acetate is added, centrifuged and dried, ethanol is added, centrifuged and dried to obtain a bio-based diol; 2) Under the protection of nitrogen, castor oil and bio-based diol are mixed, the temperature is raised to 76-80°C, isophorone diisocyanate and dibutyltin dilaurate are added, and the temperature is kept for 2-3 hours, 2,2-dihydroxymethylbutyric acid and N,N-dimethylformamide are added, and the temperature is kept for 1-2 hours, the temperature is cooled to 18-25°C, 4-amino-3-methylphenol is added, and the temperature is kept for 1-2 hours, triethylamine is added, and the temperature is kept for 10-20 minutes, composite quaternized polyethyleneimine is added, and stirred for 1-2 hours, deionized water is added, and emulsification is carried out for 1-2 hours, and rotary evaporation is carried out to obtain a modified bio-based polyurethane emulsion; The preparation of the composite quaternized polyethyleneimine comprises the following steps: Mix polyethyleneimine, methanol and 2,3-epoxypropyltrimethylammonium chloride, adjust the pH to 7.9-8.1, add epoxy POSS, keep warm at 48-52°C for 1-2 hours, add deionized water, adjust the pH to 3.9-4.1, stir for 1-2 hours to obtain composite quaternized polyethyleneimine.

2. The method for preparing a scented polyethylene garbage bag according to claim 1, characterized in that: Calculated by weight, the composition of the base material is: 40-60 parts of HDPE granules, 3-7 parts of LDPE granules, 19-25 parts of LLDPE granules, 20-22 parts of calcium carbonate, and 1-3 parts of plastic color.

3. The method for preparing a scented polyethylene garbage bag according to claim 1, characterized in that: The blow-up ratio of blown film is 2-3.

4. The method for preparing a scented polyethylene garbage bag according to claim 1, characterized in that: The mass ratio of modified bio-based polyurethane emulsion to composite silica aerogel microcapsules in the protective coating is 47:(6-8).

5. The method for preparing a scented polyethylene garbage bag according to claim 1, characterized in that: In the preparation of the composite silica aerogel microcapsules, the plant essential oil is one or a combination of lavender oil, peppermint essential oil, clove essential oil, lemon essential oil and rose essential oil.

6. The method for preparing a scented polyethylene garbage bag according to claim 1, characterized in that: In the preparation of the modified bio-based polyurethane emulsion, the mass ratio of castor oil, bio-based diol, isophorone diisocyanate, 4-amino-3-methylphenol, and composite quaternized polyethyleneimine is 5:8:16:2:

3.

7. A scented polyethylene garbage bag, characterized in that: The compound is prepared by the preparation method according to any one of claims 1 to 6.

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