Antibacterial easily-degradable plastic bottle cap and preparation method thereof

Abstract

The invention discloses an antibacterial easily-degradable plastic bottle cap and a preparation method thereof, and belongs to the field of plastic degradation. The antibacterial easy-to-degrade plastic bottle cap is mainly prepared from polylactic acid (PLA), and the antibacterial easy-to-degrade plastic bottle cap is mainly prepared from the following components in parts by weight: 50 to 60 parts of polylactic acid, 20 to 30 parts of polyhydroxyalkanoate, 10 to 15 parts of argil, 0.5 to 3 parts of quaternary ammonium salt, 0.1 to 0.5 part of antioxidant, 2 to 5 parts of stabilizer, 5 to 8 parts of plasticizer, 0.5 to 1.5 parts of lubricant and 2 to 5 parts of coloring agent. A large number of ester bonds-COOR exist on a main chain of polylactic acid, and the ester bonds-COOR are chemical bonds most likely to break in organic matter, so that polylactic acid is easy to degrade, polylactic acid can be degraded within 8-25 weeks under the composting condition and can be completely degraded within 3-5 years under the natural condition, the degradation time of traditional plastic is more than one hundred years, and polyhydroxyalkanoate is adopted as an auxiliary material, so that the cost is reduced, and the environment is protected. The polyhydroxyalkanoate is an intracellular polyester synthesized by many bacteria, and after the polyhydroxyalkanoate is fused with the polylactic acid, the biodegradability is further improved.

Description

Technical Field

[0001] The invention relates to the technical field of plastic degradation, in particular to an antibacterial and easily degradable plastic bottle cap and a preparation method thereof. Background Art

[0002] Antibacterial degradable plastic is a plastic material that combines antibacterial properties with degradability. It not only has the ability to inhibit or kill bacteria, molds, algae and other microorganisms, but also can degrade in the natural environment to reduce environmental pollution. Antibacterial degradable plastic refers to adding antibacterial agents to ordinary plastics so that it can inhibit or kill bacteria, molds, algae and other microorganisms contaminated on the plastic surface in the use environment. At the same time, this plastic can be degraded into environmentally harmless substances such as carbon dioxide, water and inorganic salts under natural environmental conditions. From the perspective of existing technology, common antibacterial degradable plastics have slow degradation rates, and some plastics with high degradation rates have defects in hardness and strength under normal conditions. In addition, while improving the antibacterial effect, it is necessary to add chemical substances to the plastic preparation process for antibacterial, resulting in the volatilization of harmful substances during the explanation process. To this end, we provide an antibacterial and easily degradable plastic bottle cap and a preparation method thereof. Summary of the invention

[0003] The purpose of the present invention is to provide an antibacterial and easily degradable plastic bottle cap and a preparation method thereof in view of the above technical problems, which has the advantages of high degradation speed, significant degradation and antibacterial effect, and no harmful substances are discharged during the degradation process.

[0004] To achieve this purpose, the present invention provides an antibacterial and easily degradable plastic bottle cap and a preparation method thereof, which adopts the following technical embodiments:

[0005] The invention discloses an antibacterial and easily degradable plastic bottle cap, which is mainly made of polylactic acid (PLA). The components of the antibacterial and easily degradable plastic bottle cap mainly include: polylactic acid, 50-60 parts, polyhydroxyalkanoate, 20-30 parts, clay, 10-15 parts, quaternary ammonium salt, 0.5-3 parts, antioxidant, 0.1-0.5 parts, stabilizer, 2-5 parts, plasticizer, 5-8 parts, lubricant, 0.5-1.5 parts, and colorant, 2-5 parts.

[0006] Preferably, the antioxidant is grape seed extract GSE, the stabilizer is vitamin E, the plasticizer is tri-n-butyl citrate, whose chemical name is 3-hydroxy-3-carboxytributylglutarate, the lubricant is vegetable oil, which is any one of olive oil, coconut oil, and sunflower oil, and the colorant is a natural colorant, which is any one of plant pigment, animal pigment, and microbial pigment.

[0007] Preferably, the method for preparing polylactic acid comprises the following steps:

[0008] S1: raw material preparation, preparing corn husks, crushing the corn husks, and extracting starch from them;

[0009] S2: converting starch into unrefined glucose;

[0010] S3: fermenting the unrefined glucose to convert it into lactic acid;

[0011] S4: converting the lactic acid monomer into the intermediate product lactide by dehydration cyclization reaction;

[0012] S5: Using strong acids and alkylating agents as catalysts to initiate a ring-opening polymerization reaction of lactide to form polylactic acid.

[0013] Preferably, in the above step S1, the corn husk is soaked for 7-8 hours, boiled for 3-4 hours, and then washed with clean water to remove impurities.

[0014] Preferably, in the above step S2, a catalyst is added to the starch, the catalyst is an inorganic acid, and the starch is hydrolyzed and converted into glucose under high temperature and high pressure, the temperature is maintained at 95-100°C, the pH value is 5.8-6.2, the reaction time is 90-120min, and the pressure is 240-250KPa.

[0015] Preferably, in the above step S4, the lactic acid is subjected to a dehydration cyclization reaction under high temperature and negative pressure, the temperature is maintained at 120-125° C., and the negative pressure value is -0.09 MPa to -0.1 MPa.

[0016] A method for preparing an antibacterial and easily degradable plastic bottle cap comprises the following steps:

[0017] S6: preparing materials, grinding polylactic acid, polyhydroxyalkanoate, and clay into particles and mixing them to form a base material;

[0018] S7: mixing and stirring the base materials, and sending them into an extruder for melting treatment;

[0019] S8: When the base material is heated until it is completely melted, an antioxidant, a stabilizer, a plasticizer, and a lubricant are respectively added to the melted base material, and the base material is melted again to form a blank;

[0020] S9: preliminarily cooling the blank, stirring during the cooling process, and adding quaternary ammonium salt and colorant while stirring;

[0021] S10: injecting the colored blank into a bottle cap mold through an injection molding machine, and forming the shape of the bottle cap after cooling;

[0022] S11: Demolding the bottle cap from the mold, and performing grinding and inspection on the cooled and formed bottle cap.

[0023] Preferably, in the above step S7, the melting temperature of the extruder is 240°C.

[0024] Preferably, in the above step S9, the blank is preliminarily cooled, and the quaternary ammonium salt and the colorant are added when the blank temperature is maintained at 150-120°C.

[0025] Preferably, in the above step S10, the injection molding temperature is maintained at 240-260°C.

[0026] The present invention has at least the following beneficial effects:

[0027] In the present invention, polylactic acid is used as the main material. There are a large number of ester bonds -COOR on the main chain of polylactic acid, which are the most easily broken chemical bonds in organic matter. Therefore, polylactic acid is easy to degrade. Under composting conditions, polylactic acid can be degraded within 8-25 weeks and completely degraded within 3-5 years under natural conditions, while the degradation time of traditional plastics is more than 100 years.

[0028] In the present invention, polyhydroxyalkanoate is used as an auxiliary material. Polyhydroxyalkanoate is a kind of intracellular polyester synthesized by many bacteria. After being fused with polylactic acid, the biodegradability is further improved.

[0029] In the present invention, quaternary ammonium salt is added, which is effective against a variety of microorganisms, including bacteria, viruses and fungi, and has a broad-spectrum bactericidal effect, thereby improving the antibacterial effect of polypropylene plastics and extending the service life of polypropylene plastic products;

[0030] In the present invention, a natural plasticizer, tri-n-butyl citrate, is used, which can increase the plasticity of the resin, so that the resin is easy to plasticize, and the product has softness and toughness, and improves the mechanical properties and processing properties of the plastic and is natural and pollution-free;

[0031] In the present invention, the stabilizer, colorant, lubricant and antioxidant used are all natural products, which can improve the degradation rate of the polylactic acid main body and cause no pollution during the degradation process.

[0032] Other advantages, objectives and features of the present invention will be embodied in part through the following description, and in part will be understood by those skilled in the art through study and practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 This is a comparative relationship diagram of the bacterial count test of the polypropylene PP plastic bottle cap prepared in Example 1 of the present invention;

[0034] Figure 2 This is a comparative relationship diagram of the degradation degree test of the polypropylene PP plastic bottle cap prepared in Example 1 of the present invention;

[0035] Figure 3This is a comparative relationship diagram of the degradation degree test of the polypropylene PP plastic bottle cap prepared in Example 2 of the present invention. DETAILED DESCRIPTION

[0036] In order to make the purpose, technical embodiments and advantages of the present invention more clear, the present invention is further described in detail below in conjunction with the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0037] The application principle of the present invention is described in detail below in conjunction with the accompanying drawings.

[0038] refer to Figure 1-3 , an antibacterial and easily degradable plastic bottle cap, the antibacterial and easily degradable plastic bottle cap is mainly made of polylactic acid PLA: the ingredients of the antibacterial and easily degradable plastic bottle cap mainly include: polylactic acid, 50-60 parts, polyhydroxyalkanoate, 20-30 parts, clay, 10-15 parts, quaternary ammonium salt, 0.5-3 parts, antioxidant, 0.1-0.5 parts, stabilizer, 2-5 parts, plasticizer, 5-8 parts, lubricant, 0.5-1.5 parts, colorant, 2-5 parts, the above antioxidant is grape seed extract GSE, the above stabilizer is vitamin E, the above plasticizer is tri-n-butyl citrate, the chemical name is 3-hydroxy-3-carboxyglutarate tributyl ester, the above lubricant is The vegetable oil is any one of olive oil, coconut oil, and sunflower oil. The colorant is a natural colorant, which is any one of plant pigment, animal pigment, and microbial pigment. Polylactic acid is used as the main material. There are a large number of ester bonds -COOR on the main chain of polylactic acid, which is the most easily broken chemical bond in organic matter. Therefore, polylactic acid is easy to degrade. Under composting conditions, polylactic acid can be degraded within 8-25 weeks and completely degraded within 3-5 years under natural conditions. The degradation time of traditional plastics is more than 100 years. Polyhydroxyalkanoate is used as an auxiliary material. Polyhydroxyalkanoate is an intracellular polyester synthesized by many bacteria. After being fused with polylactic acid, the biodegradability is further improved.

[0039] Wherein, the preparation method of polylactic acid comprises the following steps:

[0040] S1: raw material preparation, preparing corn husks, crushing the corn husks, and extracting starch from them;

[0041] S2: converting starch into unrefined glucose;

[0042] S3: fermenting the unrefined glucose to convert it into lactic acid;

[0043] S4: converting the lactic acid monomer into the intermediate product lactide by dehydration cyclization reaction;

[0044] S5: Using strong acids and alkylating agents as catalysts to initiate a ring-opening polymerization reaction of lactide to form polylactic acid.

[0045] Among them, in the above step S1, the corn husk is soaked for 7-8 hours, boiled in water for 3-4 hours, and then washed with clean water to remove impurities. In the above step S2, a catalyst is added to the starch, the catalyst is an inorganic acid, and the starch is hydrolyzed into glucose under high temperature and high pressure, the temperature is maintained at 95-100°C, the pH value is 5.8-6.2, the reaction time is 90-120min, and the pressure is 240-250KPa. In the above step S4, the lactic acid is subjected to a dehydration cyclization reaction under high temperature and negative pressure, the temperature is maintained at 120-125°C, and the negative pressure value is -0.09MPa to -0.1MPa.

[0046] A method for preparing an antibacterial and easily degradable plastic bottle cap comprises the following steps:

[0047] S6: preparing materials, grinding polylactic acid, polyhydroxyalkanoate, and clay into particles and mixing them to form a base material;

[0048] S7: mixing and stirring the base materials, and sending them into an extruder for melting treatment;

[0049] S8: When the base material is heated until it is completely melted, an antioxidant, a stabilizer, a plasticizer, and a lubricant are respectively added to the melted base material, and the base material is melted again to form a blank;

[0050] S9: preliminarily cooling the blank, stirring during the cooling process, and adding quaternary ammonium salt and colorant while stirring;

[0051] S10: injecting the colored blank into a bottle cap mold through an injection molding machine, and forming the shape of the bottle cap after cooling;

[0052] S11: Demolding the bottle cap from the mold, and performing grinding and inspection on the cooled and formed bottle cap.

[0053] Wherein, in the above step S7, the melting temperature of the extruder is 240° C., in the above step S9, the blank is preliminarily cooled, and quaternary ammonium salt and colorant are added when the blank temperature is maintained at 150-120° C., in the above step S10, the injection molding temperature is maintained at 240-260° C., and quaternary ammonium salt is added. Quaternary ammonium salt is effective against a variety of microorganisms, including bacteria, viruses and fungi, and has a broad-spectrum bactericidal effect, improves the antibacterial effect of polypropylene plastics, and extends the service life of polypropylene plastic products. A natural plasticizer, tri-n-butyl citrate, is used as a substance that can increase the plasticity of the resin, so that the resin is easy to plasticize, and the product is given softness and toughness, and the mechanical properties and processing properties of the plastic are improved and are naturally pollution-free. The stabilizer, colorant, lubricant, and antioxidant used are all natural products, which increase the degradation rate of the polylactic acid body and are pollution-free during the degradation process.

[0054] Embodiment 1:

[0055] The invention discloses an antibacterial and easily degradable plastic bottle cap, which is mainly made of polylactic acid (PLA). The ingredients of the antibacterial and easily degradable plastic bottle cap mainly include: polylactic acid, 60 parts; polyhydroxyalkanoate, 30 parts; clay, 10 parts; quaternary ammonium salt, 1 part; antioxidant, 0.3 parts; stabilizer, 2 parts; plasticizer, 5 parts; lubricant, 1 part; colorant, 2 parts; the antioxidant is grape seed extract (GSE); the stabilizer is vitamin E; the plasticizer is tri-n-butyl citrate, whose chemical name is 3-hydroxy-3-carboxytributyl glutarate; the lubricant is vegetable oil; and the colorant is a natural colorant.

[0056] Wherein, the preparation method of polylactic acid comprises the following steps:

[0057] S1: raw material preparation, preparing corn husks, crushing the corn husks, and extracting starch from them;

[0058] S2: converting starch into unrefined glucose;

[0059] S3: fermenting the unrefined glucose to convert it into lactic acid;

[0060] S4: converting the lactic acid monomer into the intermediate product lactide by dehydration cyclization reaction;

[0061] S5: Using strong acids and alkylating agents as catalysts to initiate a ring-opening polymerization reaction of lactide to form polylactic acid.

[0062] A method for preparing an antibacterial and easily degradable plastic bottle cap comprises the following steps:

[0063] S6: preparing materials, grinding polylactic acid, polyhydroxyalkanoate, and clay into particles and mixing them to form a base material;

[0064] S7: mixing and stirring the base materials, and sending them into an extruder for melting treatment;

[0065] S8: When the base material is heated until it is completely melted, an antioxidant, a stabilizer, a plasticizer, and a lubricant are respectively added to the melted base material, and the base material is melted again to form a blank;

[0066] S9: preliminarily cooling the blank, stirring during the cooling process, and adding quaternary ammonium salt and colorant while stirring;

[0067] S10: injecting the colored blank into a bottle cap mold through an injection molding machine, and forming the shape of the bottle cap after cooling;

[0068] S11: Demolding the bottle cap from the mold, and performing grinding and inspection on the cooled and formed bottle cap.

[0069] The experimental results show that:

[0070] The antibacterial and easily degradable plastic bottle cap prepared in Example 1 has a high antibacterial coefficient and is easily degradable. Example 1 maintains a relatively high antibacterial coefficient at room temperature. The specific antibacterial coefficient is compared with that of ordinary plastics and PP plastics. Figure 1 As shown in the figure, the degradation degree of the antibacterial and easily degradable plastic bottle cap prepared in Example 1 is significantly improved, and the degradation is basically a thousand times faster than that of the PP plastic matrix. The specific degradation is compared with ordinary plastics and PP plastics. Figure 2 shown.

[0071] The experimental data of Example 1 are compared with those of PP plastic and ordinary plastic, see Table 1.

[0072] Table 1, Parameter analysis data of PP plastic, ordinary plastic and Example 1

[0073]

[0074] Embodiment 2:

[0075] An antibacterial and easily degradable plastic bottle cap, which is mainly made of polylactic acid (PLA): the ingredients of the antibacterial and easily degradable plastic bottle cap mainly include: polylactic acid, 90 parts, clay, 10 parts, antioxidant, 0.3 parts, stabilizer, 2 parts, plasticizer, 5 parts, lubricant, 1 part, colorant, 2 parts, the antioxidant is a common antioxidant 16 on the market, the stabilizer is calcium stearate, the plasticizer is EPDM, the lubricant is polyethylene glycol, and the colorant is a pigment.

[0076] Wherein, the preparation method of polylactic acid comprises the following steps:

[0077] S1: raw material preparation, preparing corn husks, crushing the corn husks, and extracting starch from them;

[0078] S2: converting starch into unrefined glucose;

[0079] S3: fermenting the unrefined glucose to convert it into lactic acid;

[0080] S4: converting the lactic acid monomer into the intermediate product lactide by dehydration cyclization reaction;

[0081] S5: Using strong acids and alkylating agents as catalysts to initiate a ring-opening polymerization reaction of lactide to form polylactic acid.

[0082] A method for preparing an antibacterial and easily degradable plastic bottle cap comprises the following steps:

[0083] S6: preparing materials, grinding polylactic acid and clay into particles and mixing them to form a base material;

[0084] S7: mixing and stirring the base materials, and sending them into an extruder for melting treatment;

[0085] S8: When the base material is heated until it is completely melted, an antioxidant, a stabilizer, a plasticizer, and a lubricant are respectively added to the melted base material, and the base material is melted again to form a blank;

[0086] S9: preliminarily cooling the blank, stirring during the cooling process, and adding quaternary ammonium salt and colorant while stirring;

[0087] S10: injecting the colored blank into a bottle cap mold through an injection molding machine, and forming the shape of the bottle cap after cooling;

[0088] S11: Demolding the bottle cap from the mold, and performing grinding and inspection on the cooled and formed bottle cap.

[0089] The experimental results show that:

[0090] The antibacterial and easily degradable plastic bottle cap prepared in Example 1 is easily degradable. Example 1 maintains a relatively high degradation rate at room temperature. The specific degradation rate is compared with that of ordinary plastics and PP plastics. Figure 3 As shown, compared with Example 1, Example 2 has a faster degradation rate, but will leave behind substances that are harmful to the environment.

[0091] The experimental data of Example 2 are compared with those of Example 1, PP plastic and ordinary plastic, see Table 2.

[0092] Table 2, Parameter analysis data of PP plastic, ordinary plastic, Example 1 and Example 2

[0093]

[0094] The present invention discloses an antibacterial and easily degradable plastic bottle cap and a preparation method thereof. The prepared EPDM composition has high heat resistance and high tensile strength, and magnesium oxide is used as an activator to replace zinc oxide to avoid zinc in the product. The above embodiments are only used to illustrate but not limit the technical embodiments of the present invention. Relevant technicians in this field can make reasonable modifications or equivalent substitutions to the present invention, but any modifications and partial substitutions that do not depart from the spirit and scope of the present invention should be covered within the scope of the claims of the present invention.

[0095] The contents not described in detail in this specification belong to the prior art known to professional and technical personnel in this field.

Claims

1. An antibacterial and easily degradable plastic bottle cap, characterized in that: The antibacterial and easily degradable plastic bottle caps are mainly made of polylactic acid PLA: the ingredients of the antibacterial and easily degradable plastic bottle caps mainly include: polylactic acid, 50-60 parts, polyhydroxyalkanoates, 20-30 parts, clay, 10-15 parts, quaternary ammonium salts, 0.5-3 parts, antioxidants, 0.1-0.5 parts, stabilizers, 2-5 parts, plasticizers, 5-8 parts, lubricants, 0.5-1.5 parts, colorants, 2-5 parts.

2. The antibacterial and easily degradable plastic bottle cap according to claim 1, characterized in that: The antioxidant is grape seed extract GSE, the stabilizer is vitamin E, the plasticizer is tri-n-butyl citrate, whose chemical name is 3-hydroxy-3-carboxytributylglutarate, the lubricant is vegetable oil, which is any one of olive oil, coconut oil, and sunflower oil, and the colorant is a natural colorant, which is any one of plant pigment, animal pigment, and microbial pigment.

3. The antibacterial and easily degradable plastic bottle cap according to claim 1, characterized in that: The preparation method of polylactic acid comprises the following steps: S1: raw material preparation, preparing corn husks, crushing the corn husks, and extracting starch from them; S2: converting starch into unrefined glucose; S3: fermenting the unrefined glucose to convert it into lactic acid; S4: converting the lactic acid monomer into the intermediate product lactide by dehydration cyclization reaction; S5: Using strong acids and alkylating agents as catalysts to initiate a ring-opening polymerization reaction of lactide to form polylactic acid.

4. The method for preparing an antibacterial and easily degradable plastic bottle cap according to claim 3, characterized in that: In the above step S1, the corn husk is soaked for 7-8 hours, boiled for 3-4 hours, and then washed with clean water to remove impurities.

5. The method for preparing an antibacterial and easily degradable plastic bottle cap according to claim 3, characterized in that: In the above step S2, a catalyst is added to the starch, the catalyst is an inorganic acid, and the starch is hydrolyzed into glucose under high temperature and high pressure, the temperature is maintained at 95-100°C, the pH value is 5.8-6.2, the reaction time is 90-120min, and the pressure is 240-250KPa.

6. The method for preparing an antibacterial and easily degradable plastic bottle cap according to claim 3, characterized in that: In the above step S4, the lactic acid is subjected to a dehydration cyclization reaction under high temperature and negative pressure, the temperature is maintained at 120-125° C., and the negative pressure value is -0.09 MPa to -0.1 MPa.

7. A method for preparing an antibacterial and easily degradable plastic bottle cap, characterized in that: The following steps are involved: S6: preparing materials, grinding polylactic acid, polyhydroxyalkanoate, and clay into particles and mixing them to form a base material; S7: mixing and stirring the base materials, and sending them into an extruder for melting treatment; S8: When the base material is heated until it is completely melted, an antioxidant, a stabilizer, a plasticizer, and a lubricant are respectively added to the melted base material, and the base material is melted again to form a blank; S9: preliminarily cooling the blank, stirring during the cooling process, and adding quaternary ammonium salt and colorant while stirring; S10: injecting the colored blank into a bottle cap mold through an injection molding machine, and forming the shape of the bottle cap after cooling; S11: Demolding the bottle cap from the mold, and performing grinding and inspection on the cooled and formed bottle cap.

8. The antibacterial and easily degradable plastic bottle cap and the preparation method thereof according to claim 7, characterized in that: In the above step S7, the melting temperature of the extruder is 240°C.

9. The antibacterial and easily degradable plastic bottle cap and the preparation method thereof according to claim 7, characterized in that: In the above step S9, the blank is preliminarily cooled, and the quaternary ammonium salt and the colorant are added when the blank temperature is maintained at 150-120°C.

10. The antibacterial and easily degradable plastic bottle cap and the preparation method thereof according to claim 7, characterized in that: In the above step S10, the injection molding temperature is maintained at 240-260°C.

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