Environment-friendly antibacterial PP (polypropylene) plastic and preparation process thereof

Abstract

The invention relates to an environment-friendly antibacterial PP plastic and a preparation process thereof, and belongs to the technical field of high polymer materials. The preparation method comprises the following steps: pretreating the PP powder, stirring the pretreated PP powder, the bacteriostatic agent, the white oil and the stabilizer in a high-speed stirrer to obtain a mixed raw material, adding the mixed raw material into a double-screw extruder, carrying out melt extrusion, carrying out cold drawing granulation, and carrying out injection molding to prepare a sample. The antibacterial agent is a mixture of polylysine hydrochloride, polylysine citrate and natamycin, and the stabilizer is a mixture of phosphite and any one of 2, 6-di-tert-butyl-4-methylphenol, bis (3, 5-di-tert-butyl-4-hydroxyphenyl) thioether and tetrakis [beta-(3, 5-di-tert-butyl-4-hydroxyphenyl) propionic acid] pentaerythritol ester, and the stabilizer is a mixture of phosphite and any one of 2, 6-di-tert-butyl-4-methylphenol, bis (3, 5-di-tert-butyl-4-hydroxyphenyl) thioether and tetrakis [beta-(3, 5-di-tert-butyl-4-hydroxyphenyl) propionic acid] pentaerythritol ester. According to the production formula and the preparation process provided by the invention, the problem that toxic substances are easily generated to pollute the environment in a solution grafting method is avoided, the problem that the strength of a product is easily reduced in an existing melting method is also solved, and meanwhile, good antibacterial performance is also achieved.

Description

Technical Field

[0001] The invention belongs to the technical field of polymer materials and relates to an environmentally friendly antibacterial PP plastic and a preparation process. Background Art

[0002] Polypropylene is a commonly used plastic with excellent performance and low production cost. It is widely used in various plastic products. Since it often comes into contact with the human body in life, the industry's requirements for hygiene and safety have been continuously increasing in recent years. Antibacterial plastics can inhibit or kill bacteria, fungi, etc. Antibacterial polypropylene, as a hot spot in plastic research, has made some progress in China.

[0003] In order to effectively kill or inhibit bacteria attached to the surface of plastics, people usually add antibacterial agents to plastics to make antibacterial plastics, so that the plastics themselves have antibacterial properties, which can kill or inhibit bacteria contaminated on plastics within a certain period of time. Compared with conventional chemical and physical methods, the use of antibacterial plastics has a long sterilization time, which is both economical and convenient. The development and application of antibacterial plastics are of great significance to the protection of human health. Since antibacterial plastics can fundamentally reduce or avoid cross-infection between people, people and objects, and objects and objects, plastic products with antibacterial functions are generally valued and welcomed by people. At present, the production of antibacterial plastics mainly grafts antibacterial agents onto polypropylene through solution grafting or melting methods, so that PP plastics can obtain antibacterial effects. However, the amount of solvent required for the solution grafting method is large, and distillation separation is required. The product must also be separated from the solvent and dried. The process is complicated and the solvent is often toxic, which seriously pollutes the environment. The melting method easily causes polypropylene to degrade, resulting in a decrease in the strength of the product. Therefore, providing an environmentally friendly antibacterial PP plastic and a preparation process is a technical problem that needs to be solved at present.

[0004] Patent CN116535772A discloses a synthesis process of antibacterial PP material. A polypropylene material with excellent and lasting antibacterial and flame retardant properties is prepared, maleic anhydride grafted polypropylene wax and N-(dibromoethyl)acetamide are subjected to ring-opening reaction to introduce bromine atoms and carboxyl groups, the carboxyl groups are reduced by NaBH4-I2, and then the introduced bromine atoms are reacted with triethylamine for quaternization to obtain quaternary ammonium salt type polypropylene wax, cyanuric chloride is reacted with N,N-di(ethylphospho)biguanide and quaternary ammonium salt type polypropylene wax, wherein cyanuric chloride is used as a bridge to link the two antibacterial substances, and then applied to the polypropylene material, so that the prepared PP material has good antibacterial effect, and also improves the antibacterial effect of the finished product using the PP material.

[0005] Patent CN116178845A discloses a method for preparing antibacterial and weather-resistant PE / PP plastics, comprising the following steps: preparing functional additives, putting polypropylene, polyethylene, functional additives, maleic anhydride, polyolefin elastomer and polyethylene wax into a high-speed mixer in proportion, mixing at high speed, extruding and molding through a twin-screw extruder, cooling and molding to obtain PE / PP plastics. The present invention obtains functional additives by modifying nano zinc oxide and grafting organic molecular chains of the modifier on the surface, which can not only promote the uniform dispersion of zinc oxide in plastics, but also the halamine functional groups contained in the modifier molecules produce synergistic antibacterial effects with zinc oxide, and the functional groups of hydroxybenzophenone contained in the modifier molecules produce synergistic ultraviolet resistance with zinc oxide.

[0006] Patent CN112341707A discloses a method for preparing an antibacterial PP plastic, which takes PP resin as the main material, adds polyethylene glycol ether, coupling agent, antioxidant, plasticizer and other fillers, and adds antibacterial gel, seaweed carbon quantum dots and cinnamaldehyde. Cinnamaldehyde easily migrates to the plastic surface in the plastic material, and is the first main antibacterial molecule of the component. It cooperates with the antibacterial gel and seaweed carbon quantum dots inside the plastic to exert long-lasting antibacterial properties, and has good antibacterial properties and good mechanical properties.

[0007] Patent CN109293838A discloses a novel grafted antibacterial polypropylene, which is mainly prepared by grafting polypropylene with maleic anhydride to obtain an intermediate, and then reacting the intermediate with a brominated organic antibacterial agent to obtain the intermediate; wherein the organic antibacterial agent molecule contains one or more -NS bonds, one or more C=C bonds, and one or more cyclic structures. The novel grafted antibacterial polypropylene of the present invention can be used as an antibacterial PP material alone, or as an antibacterial additive masterbatch blended with polypropylene, or multi-layer co-extruded with PP to improve the antibacterial properties of the PP surface. Summary of the invention

[0008] The purpose of the present invention is to provide an environmentally friendly antibacterial PP plastic and a preparation process, which has the characteristics of being environmentally friendly and pollution-free and being able to effectively inhibit or kill bacteria.

[0009] The purpose of the present invention can be achieved through the following technical solutions:

[0010] A preparation process of environmentally friendly antibacterial PP plastic, comprising the following steps:

[0011] (1) PP powder pretreatment;

[0012] (2) placing the pretreated PP powder, the antibacterial agent, the white oil and the stabilizer in a high-speed mixer and stirring to obtain a mixed raw material;

[0013] (3) The mixed raw materials are fed into a twin-screw extruder for melt extrusion, cold drawing and granulation, and injection molding for sample preparation.

[0014] As a preferred technical solution of the present invention, the pretreatment in step (1) refers to placing the PP powder in a constant temperature drying oven at 80° C. and drying for 3 to 5 hours.

[0015] As a preferred technical solution of the present invention, the antibacterial agent in step (2) is a mixture of polylysine hydrochloride, polylysine citrate and natamycin.

[0016] As a preferred technical solution of the present invention, the mass ratio of polylysine hydrochloride, polylysine citrate and natamycin is 2-4:2-4:1-3.

[0017] As a preferred technical solution of the present invention, the stabilizer in step (2) is a mixture of any one of 2,6-di-tert-butyl-4-methylphenol, bis(3,5-di-tert-butyl-4-hydroxyphenyl) sulfide, and pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate and phosphite.

[0018] As a preferred technical solution of the present invention, the mass ratio of any one of the 2,6-di-tert-butyl-4-methylphenol, bis(3,5-di-tert-butyl-4-hydroxyphenyl) sulfide, and pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate to the phosphite is 1-3:4-8.

[0019] As a preferred technical solution of the present invention, the mass ratio of the pretreated PP powder, antibacterial agent, white oil and stabilizer in step (2) is 1000-2000:10-16:1-3:18-20.

[0020] As a preferred technical solution of the present invention, the stirring speed of the high-speed stirrer described in step (2) is 800-1200 r / min, and the stirring time is 20-30 min.

[0021] As a preferred technical solution of the present invention, the screw speed of the twin-screw extruder described in step (3) is 80-120 r / min and the temperature is 180-220°C.

[0022] An environmentally friendly antibacterial PP plastic is prepared by the above-mentioned preparation method.

[0023] Beneficial effects of the present invention:

[0024] (1) The environmentally friendly antibacterial PP plastic produced by the production formula and preparation process provided by the present invention avoids the problem of easily generating toxic substances that pollute the environment during the process of grafting antibacterial groups using the solution grafting method, thereby greatly reducing pollution to the environment.

[0025] (2) The environmentally friendly antibacterial PP plastic produced by the production formula and preparation process provided by the present invention overcomes the problem that the existing melting method easily leads to a decrease in product strength. The present invention avoids the problem of raw material degradation that easily occurs during the production process by adding a unique stabilizer, thereby effectively improving the strength of the product.

[0026] (3) The environmentally friendly antibacterial PP plastic produced by the production formula and preparation process provided by the present invention has good antibacterial properties, and the antibacterial rate against Escherichia coli and Staphylococcus aureus can reach 99.96%. DETAILED DESCRIPTION

[0027] In order to further illustrate the technical means and effects adopted by the present invention to achieve the predetermined invention purpose, the specific implementation methods, structures, features and effects of the present invention are described in detail below in combination with the embodiments.

[0028] Example 1

[0029] A preparation process of environmentally friendly antibacterial PP plastic, comprising the following steps:

[0030] (1) Place the PP powder in a constant temperature drying oven at 80°C and dry for 3 h;

[0031] (2) mixing polylysine hydrochloride, polylysine citrate and natamycin in a mass ratio of 2:2:1 to obtain an antibacterial agent;

[0032] (3) mixing 2,6-di-tert-butyl-4-methylphenol and phosphite in a mass ratio of 1:4 to obtain a stabilizer;

[0033] (4) placing the pretreated PP powder, antibacterial agent, white oil and stabilizer in a high-speed mixer at a mass ratio of 1000:10:1:18, stirring at a speed of 800 r / min for 30 min to obtain a mixed raw material;

[0034] (5) The mixed raw materials were fed into a twin-screw extruder at a screw speed of 80 r / min and a temperature of 180° C. for melt extrusion, cold drawing granulation, and injection molding.

[0035] Example 2

[0036] A preparation process of environmentally friendly antibacterial PP plastic, comprising the following steps:

[0037] (1) Place the PP powder in a constant temperature drying oven at 80°C and dry for 4 hours;

[0038] (2) mixing polylysine hydrochloride, polylysine citrate and natamycin in a mass ratio of 3:3:2 to obtain an antibacterial agent;

[0039] (3) mixing bis(3,5-di-tert-butyl-4-hydroxyphenyl) sulfide and phosphite in a mass ratio of 2:6 to obtain a stabilizer;

[0040] (4) placing the pretreated PP powder, antibacterial agent, white oil and stabilizer in a high-speed mixer at a mass ratio of 1500:13:2:19, stirring at a speed of 1000 r / min for 25 min to obtain a mixed raw material;

[0041] (5) The mixed raw materials were fed into a twin-screw extruder at a screw speed of 100 r / min and a temperature of 200° C. The mixture was melt-extruded, cold-pulled into pellets, and injection-molded to prepare samples.

[0042] Example 3

[0043] A preparation process of environmentally friendly antibacterial PP plastic, comprising the following steps:

[0044] (1) Place the PP powder in a constant temperature drying oven at 80°C and dry for 5 hours;

[0045] (2) mixing polylysine hydrochloride, polylysine citrate and natamycin in a mass ratio of 4:4:3 to obtain an antibacterial agent;

[0046] (3) pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] and phosphite are mixed in a mass ratio of 3:8 to obtain a stabilizer;

[0047] (4) placing the pretreated PP powder, antibacterial agent, white oil and stabilizer in a high-speed mixer at a mass ratio of 2000:16:3:20, stirring at a speed of 1200 r / min for 20 min to obtain a mixed raw material;

[0048] (5) The mixed raw materials were fed into a twin-screw extruder at a screw speed of 120 r / min and a temperature of 220° C. for melt extrusion, cold drawing granulation, and injection molding.

[0049] Comparative Example 1

[0050] A preparation process of environmentally friendly antibacterial PP plastic, comprising the following steps:

[0051] (1) Place the PP powder in a constant temperature drying oven at 80°C and dry for 4 hours;

[0052] (2) mixing bis(3,5-di-tert-butyl-4-hydroxyphenyl) sulfide and phosphite in a mass ratio of 2:6 to obtain a stabilizer;

[0053] (3) placing the pretreated PP powder, white oil and stabilizer in a high-speed mixer at a mass ratio of 1500:2:19, stirring at a speed of 1000 r / min for 25 min to obtain a mixed raw material;

[0054] (4) The mixed raw materials were fed into a twin-screw extruder at a screw speed of 100 r / min and a temperature of 200° C. The mixture was melt-extruded, cold-pulled into pellets, and injection-molded to prepare samples.

[0055] Comparative Example 2

[0056] A preparation process of environmentally friendly antibacterial PP plastic, comprising the following steps:

[0057] (1) Place the PP powder in a constant temperature drying oven at 80°C and dry for 4 hours;

[0058] (2) mixing polylysine hydrochloride, polylysine citrate and natamycin in a mass ratio of 3:3:2 to obtain an antibacterial agent;

[0059] (3) placing the pretreated PP powder, the antibacterial agent and the white oil in a high-speed mixer at a mass ratio of 1500:13:2, stirring at a speed of 1000 r / min for 25 min to obtain a mixed raw material;

[0060] (4) The mixed raw materials were fed into a twin-screw extruder at a screw speed of 100 r / min and a temperature of 200° C. The mixture was melt-extruded, cold-pulled into pellets, and injection-molded to prepare samples.

[0061] Comparative Example 3

[0062] A preparation process of environmentally friendly antibacterial PP plastic, comprising the following steps:

[0063] (1) Place the PP powder in a constant temperature drying oven at 80°C and dry for 4 hours;

[0064] (2) placing the pretreated PP powder and white oil in a high-speed mixer at a mass ratio of 1500:2, stirring at a speed of 1000 r / min for 25 min to obtain a mixed raw material;

[0065] (3) The mixed raw materials were fed into a twin-screw extruder at a screw speed of 100 r / min and a temperature of 200°C for melt extrusion, cold drawing granulation, and injection molding.

[0066] Performance Test:

[0067] Pure PP plastic was used as a blank control group, the environmentally friendly PP plastics obtained in Examples 1 to 3 were used as experimental groups 1 to 3, and the products obtained in Comparative Examples 1 to 3 were used as control groups 1 to 3.

[0068] According to GB / T31402-2015, antibacterial tests were conducted on experimental groups 1 to 3, control groups 1 to 3 and a blank control group, and the antibacterial rates of antibacterial PP products against Escherichia coli and Staphylococcus aureus were tested in a biochemical incubator. The results are shown in Table 1 below.

[0069] According to GB / T1040.2-2022, the tensile performance test was conducted on the experimental groups 1 to 3, the control groups 1 to 3 and the blank control group, with a tensile rate of 200 mm / min; according to GB / T1843-2008, the notched impact strength test was conducted on the experimental groups 1 to 3, the control groups 1 to 3 and the blank control group, with a pendulum energy of 5 J and a notch depth of 2 mm. The results are shown in Tables 2 and 3 below.

[0070] It can be seen from Table 1 that pure PP plastic has basically no antibacterial property; the environmentally friendly PP plastic prepared by Examples 1 to 3 using the formula and preparation process provided by the present invention has good antibacterial property, and the antibacterial rate can reach up to 99.99%.

[0071] It can be seen from Table 2 and Table 3 that the environmentally friendly PP plastics prepared by Examples 1 to 3 using the formula and preparation process provided by the present invention have good strength. The strength of the product with only antibacterial agent added but not stabilizer is better than the strength of the product without antibacterial agent and stabilizer or the strength of pure PP plastic; the strength of the product with only stabilizer added but not antibacterial agent is worse than the strength of the product with antibacterial agent and stabilizer added. It is speculated that the antibacterial agent may have a synergistic effect on the stabilizer.

[0072] Table 1 Antibacterial rate (%) test results of Escherichia coli and Staphylococcus aureus

[0073]

[0074] Table 2 Tensile strength (MPa) test results

[0075]

[0076] Table 3 Notched impact strength (KJ / m 2 )Test Results

[0077]

[0078]

[0079] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any form. Although the present invention has been disclosed as a preferred embodiment as above, it is not used to limit the present invention. Any technical personnel in this field can make some changes or modify the technical contents disclosed above into equivalent embodiments without departing from the scope of the technical solution of the present invention. However, any brief modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention are still within the scope of the technical solution of the present invention.

Claims

1. A preparation process of environmentally friendly antibacterial PP plastic, characterized in that: The following steps are involved: (1) PP powder pretreatment; (2) placing the pretreated PP powder, the antibacterial agent, the white oil and the stabilizer in a high-speed mixer and stirring to obtain a mixed raw material; (3) The mixed raw materials are fed into a twin-screw extruder for melt extrusion, cold drawing and granulation, and injection molding for sample preparation.

2. The preparation process of an environmentally friendly antibacterial PP plastic according to claim 1, characterized in that: The pretreatment in step (1) refers to placing the PP powder in a constant temperature drying oven at 80° C. and drying for 3 to 5 hours.

3. The preparation process of an environmentally friendly antibacterial PP plastic according to claim 1, characterized in that: The antibacterial agent in step (2) is a mixture of polylysine hydrochloride, polylysine citrate and natamycin.

4. The preparation process of an environmentally friendly antibacterial PP plastic according to claim 3, characterized in that: The mass ratio of the polylysine hydrochloride, polylysine citrate and natamycin is 2-4:2-4:1-3.

5. The preparation process of an environmentally friendly antibacterial PP plastic according to claim 1, characterized in that: The stabilizer in step (2) is a mixture of any one of 2,6-di-tert-butyl-4-methylphenol, bis(3,5-di-tert-butyl-4-hydroxyphenyl) sulfide, and pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate and phosphite.

6. The process for preparing an environmentally friendly antibacterial PP plastic according to claim 5, characterized in that: The mass ratio of any one of the 2,6-di-tert-butyl-4-methylphenol, bis(3,5-di-tert-butyl-4-hydroxyphenyl) sulfide and pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate to the phosphite is 1-3:4-8.

7. The process for preparing an environmentally friendly antibacterial PP plastic according to claim 1, characterized in that: The mass ratio of the pretreated PP powder, antibacterial agent, white oil and stabilizer in step (2) is 1000-2000:10-16:1-3:18-20.

8. The process for preparing an environmentally friendly antibacterial PP plastic according to claim 1, characterized in that: The stirring speed of the high-speed stirrer described in step (2) is 800-1200 r / min, and the stirring time is 20-30 min.

9. The process for preparing an environmentally friendly antibacterial PP plastic according to claim 1, characterized in that: The screw speed of the twin-screw extruder in step (3) is 80-120 r / min, and the temperature is 180-220°C.

10. An environmentally friendly antibacterial PP plastic prepared according to the preparation process according to any one of claims 1 to 9.

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