Preparation method of antibacterial polymer with low antibacterial agent content and coating structure

Abstract

The present invention discloses a method for preparing an antibacterial polymer with a low antibacterial agent content and a coating structure, comprising: melt-blending and extruding an antibacterial agent with matching polarity and a coating layer polymer; and co-injecting the extruded product with a core layer polymer having a certain polarity and viscosity difference under specific conditions to obtain the antibacterial polymer with a low antibacterial agent content and a coating structure. The method prepares a polymer antibacterial composite material with a coating structure, and the antibacterial agent is selectively distributed in the coating layer polymer. While ensuring high antibacterial efficiency, the amount of the antibacterial agent used is greatly reduced, the cost is low, the preparation process is simple, and it is easy to industrialize.

Description

Technical Field

[0001] The invention relates to the technical field of polymer materials, and in particular to a method for preparing an antibacterial polymer with a low antibacterial agent content and a coating structure. Background Art

[0002] Polymer materials are widely used in products that come into close contact with humans, such as packaging, daily necessities, and electronic appliances. The development of antimicrobial polymers, which block the spread of bacteria through polymer-based products, plays a crucial role in humanity's fight against bacteria. However, currently, only polymers used in medical devices, food packaging, and children's toys have been developed into antimicrobial polymers. A large number of products in other sectors still use non-antimicrobial polymers. These non-antimicrobial polymers allow bacteria to adhere to the products they are made from, leading to their widespread spread.

[0003] The most critical component in the formulation of antibacterial polymer materials is the antibacterial agent. Currently, the antibacterial agents used to prepare antibacterial polymer materials include inorganic antibacterial agents and organic antibacterial agents. Zinc oxide, as the main environmentally friendly inorganic antibacterial agent, has the advantages of migration resistance and long service life, but its antibacterial efficiency is not high. The antibacterial efficiency of organic antibacterial agents is generally high, but most environmentally friendly organic antibacterial agents are small molecules, which are easily migrated and lost in the polymer matrix or on the polymer surface, not only polluting the environment and damaging human health, but also resulting in a short service life of antibacterial polymer products prepared with organic antibacterial agents. Organic-inorganic antibacterial agents are a type of inorganic-organic composite antibacterial agent with high antibacterial rate, low migration rate, good heat resistance, safety, environmental protection and low price. After melt blending with polymers, they can significantly improve the antibacterial properties of polymers and have good application prospects in the field of polymer antibacterial modification.

[0004] Conventional methods for preparing antimicrobial polymer materials include melt blending, surface coating, or grafting. Melt blending involves melting and mixing an antimicrobial agent with a polymer under heating and shearing conditions to uniformly distribute the antimicrobial agent on the surface and within the polymer material. Surface coating or grafting involves coating or chemically grafting the antimicrobial agent onto the material surface. Although melt blending is a simple process for preparing antimicrobial polymer materials, it requires a large amount of antimicrobial agent and is costly. Only the antimicrobial agent on the surface of the material has an antimicrobial effect, while the antimicrobial agent within the material does not. Antimicrobial polymer materials prepared by surface coating or grafting require additional coating or grafting steps, resulting in complex processes. Furthermore, the antimicrobial coating layer has poor bonding with the polymer matrix and is easily detached, shortening the service life of the antimicrobial polymer material. Chemical grafting is a demanding process for preparing antimicrobial polymer materials, making large-scale industrial production difficult and costly. Therefore, there is an urgent need to develop a novel antimicrobial polymer material and its preparation technology that offers advantages such as low cost, simple preparation, long service life, high performance, and efficient antimicrobial efficacy. Summary of the Invention

[0005] In order to overcome the shortcomings of the above-mentioned background technology, the present invention provides a method for preparing an antibacterial polymer with a low antibacterial agent content and a coating structure.

[0006] The present invention adopts an organic-inorganic composite antimicrobial agent that is environmentally friendly, migration-resistant, and has adjustable surface polarity and antimicrobial properties, regulates the polarity of the composite antimicrobial agent and the coating layer polymer material, and selectively distributes the organic-inorganic composite antimicrobial agent in the coating layer polymer. The polarity, viscosity ratio, and processing technology of the coating layer polymer material containing the antimicrobial agent and the core layer polymer material are further regulated to obtain a coating structure polymer with high efficiency, low cost, and long service life, in which the coating layer contains the antimicrobial agent but the core layer does not contain the antimicrobial agent.

[0007] The technical solutions of the present invention are as follows:

[0008] A method for preparing an antibacterial polymer with a low antibacterial agent content and a coating structure comprises the following steps:

[0009] (1) Using organic antimicrobial agents to modify inorganic antimicrobial agents to prepare organic-inorganic composite antimicrobial agents;

[0010] The organic antibacterial agent is selected from one or more of cinnamaldehyde, thymol, carvacrol, and citral;

[0011] The inorganic antibacterial agent is selected from one or more of zinc oxide and titanium dioxide;

[0012] By regulating the type and content of the organic antimicrobial agent on the surface of the inorganic antimicrobial agent, an organic-inorganic composite antimicrobial agent with good compatibility with the coating polymer can be produced. The compatibility is calculated by measuring the contact angles of 2 μL of water with the organic-inorganic composite antimicrobial agent and the coating polymer, and the difference between the two contact angles is controlled to be within 5°.

[0013] (2) melting, shearing, and mixing the organic-inorganic composite antimicrobial agent, the antioxidant, and the coating layer polymer in a twin-screw extruder to obtain a coating layer polymer composite material containing the antimicrobial agent;

[0014] The mass ratios of the organic-inorganic composite antibacterial agent, antioxidant and coating polymer are: 1-30 parts, 0.1-5 parts and 100 parts respectively, preferably the mass ratios of the three are: 1-20 parts, 0.1-1 parts and 100 parts respectively;

[0015] The antioxidant is one or more of pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate, tris[2,4-di-tert-butylphenyl]phosphite, and β-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate;

[0016] The coating layer polymer is generally selected from LDPE, HDPE, PA6, ABS, etc.

[0017] The temperature range of the extruder is 160-230°C, preferably 180-220°C, and the speed of the extruder is 50-100 rpm, preferably 60-90 rpm;

[0018] (3) uniformly mixing the coating layer polymer composite material containing the antimicrobial agent and the core layer polymer particles, and then injection molding them in an injection molding machine to obtain the antimicrobial polymer with a low antimicrobial agent content and a coating structure;

[0019] The mass ratio of the coating layer polymer composite material containing the antibacterial agent to the core layer polymer particles is: 1-50 parts, 50-99 parts, preferably the mass ratio of the two is: 20-40 parts, 60-80 parts;

[0020] The core layer polymer particles are generally made of PP, PLA, PE, etc.

[0021] The temperature range of the injection molding machine is 160-230°C, preferably 180-220°C, and the injection speed of the injection molding machine is 40-90 cm 3 / s, preferably 50-70cm 3 / s;

[0022] The coating layer polymer composite material containing an antibacterial agent and the core layer polymer particles have certain differences in polarity and viscosity; the contact angle difference between the coating layer polymer composite material containing an antibacterial agent and the core layer polymer particles is controlled within a range of 1 to 20°, preferably 3 to 10°, when tested with a non-polar test liquid (such as liquid paraffin, diiodomethane, etc.); the difference is controlled within a range of 1 to 50°, preferably 7 to 30°, when tested with a polar test liquid (such as water, glycerol, etc.); the viscosity ratio of the coating layer polymer composite material containing an antibacterial agent to the core layer polymer particles under the injection molding process of an injection molding machine is controlled within a range of 1.0 to 5.0, preferably 1.5 to 3.0.

[0023] Furthermore, the preparation method of the organic-inorganic composite antibacterial agent of the present invention is as follows (the following parts are all by mass):

[0024] (1) Add 10-30 parts of silane coupling agent and 75-90 parts of ZnO to a mixed solvent of water and ethanol, stir at a stirring rate of 200 r / min for 6 hours, centrifuge, and take a precipitate; replace the ZnO in the above operation with the precipitate, repeat the above operation 5 times, and dry the precipitate for use;

[0025] The silane coupling agent is KH550, KH560 or KH570;

[0026] (2) adding the dried product obtained in step (1) to anhydrous ethanol, ultrasonically dispersing for 30 minutes, adding 5 to 15 parts of cinnamaldehyde and mixing evenly, then centrifugally washing with anhydrous ethanol, drying, and setting aside;

[0027] (3) 4.5 to 18 parts of thymol were added to carbon tetrachloride to dissolve the thymol, and then 5 to 20 parts of N-bromosuccinimide were added. The mixture was condensed and refluxed (60° C.) for 6 hours. The reaction was then filtered and the solvent was evaporated under reduced pressure to obtain a light yellow liquid product.

[0028] (4) adding the dried product obtained in step (2) to carbon tetrachloride and ultrasonically dispersing for 30 minutes to obtain a dispersion; adding the liquid product obtained in step (3) to the dispersion, condensing and refluxing (60° C.), reacting for 6 hours, then filtering, washing the filtered product with carbon tetrachloride, and vacuum drying to obtain the organic-inorganic composite antibacterial agent.

[0029] Compared with the prior art, the advantages of the present invention are as follows:

[0030] (1) Antimicrobial agents are environmentally friendly, migration-resistant, highly effective, and have a long service life.

[0031] (2) Small amount of antimicrobial agent is used, and the cost is low. Through the theory of selective distribution of inorganic particles, the antimicrobial agent is distributed only in the coating layer, and the amount of antimicrobial agent used in the entire polymer is relatively small, which greatly reduces the cost of the antimicrobial polymer.

[0032] (3) The preparation process of antibacterial polymer is simple. The antibacterial polymer sample with coating structure can be prepared by conventional screw extrusion, injection molding and other processes. The process is simple and feasible and easy to industrialize. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 Schematic diagram of the structure of antibacterial polymer composites with low antibacterial agent content and coating structure. DETAILED DESCRIPTION

[0034] The present invention is further described below by means of specific examples, but the protection scope of the present invention is not limited thereto.

[0035] The contact angle, viscosity, antibacterial performance and mechanical property testing methods involved in the present invention are as follows:

[0036] Contact angle test method: (1) Dry the antibacterial powder to constant weight, place it in a 30cm×20cm powder tank and press it. Dry the coating layer and core layer polymers in an oven to constant weight, and inject them into the test flat plate specimens. Before surface testing, the area (length×width) of each flat plate is cut to 20mm×20mm. (2) Use a micro-injector to vertically drip the test liquid on the sample surface at a distance of about 3mm from the solid surface to form a droplet. The measurement time does not exceed 1min. The average value of the contact angles of 10 times (each time with an interval of 2s) is taken as the contact angle of the sessile drop, and the average value of the contact angles of 10 sessile drops is taken as the contact angle of the liquid on the surface. All measurements are carried out at room temperature (25℃). The test liquids are all analytical grade reagents, and high-purity water is freshly prepared using a high-purity water analyzer.

[0037] Viscosity test method of antimicrobial coating layer polymer composite material and core layer polymer: (1) Antioxidant, coating layer material and antimicrobial agent are mixed and extruded in a twin-screw extruder to obtain a coating layer composite material containing antimicrobial agent. (2) After drying the composite material to constant weight at a certain temperature, add it into the barrel of a high-pressure capillary rheometer and compact it. After it is completely melted, stabilize it for 5 minutes and then 4 s -1 The test was carried out at a shear rate of 10, and a total of 10 shear rate points were taken to obtain a curve showing that the melt viscosity changes with the shear rate.

[0038] The mechanical properties of the antibacterial polymer with a low content of antibacterial agent and a coating structure are tested in accordance with GB / T1040.2-2006, GB / T1043.1-2008, and GB / T9341-2008 to test the tensile, impact and bending properties of injection molded standard test bars.

[0039] The antibacterial performance test of the antibacterial polymer with a low content of antibacterial agent and a coating structure was carried out in accordance with the national standard GB / T31402-2015.

[0040] Example 1

[0041] The preparation method of the organic-inorganic composite antibacterial agent is as follows:

[0042] (1) Dissolve 20 g of KH550 and 80 g of ZnO in a 250 mL three-necked flask containing water and ethanol (volume ratio 1:4). Stir the mixture with magnetic stirring at 200 rpm for 6 h. Centrifuge the mixture at 5000 rpm and collect the precipitate. Repeat this process five times and dry the mixture for 24 h.

[0043] (2) The dried product obtained in step (1) was dissolved in a 250 mL three-necked flask filled with anhydrous ethanol, ultrasonically dispersed for 30 min, and then 15 g of cinnamaldehyde (CA) was added. The mixture was washed three times by centrifugation with anhydrous ethanol and dried for 24 h.

[0044] (3) Add 4.5 g of thymol (THY) to a 100 mL single-necked flask containing carbon tetrachloride to dissolve the thymol. Add 5 g of N-bromosuccinimide (NBS) and reflux under condensation for 6 h. Distill the resulting filtrate on a rotary evaporator to obtain a light yellow liquid product.

[0045] (4) The dried product obtained in step (2) was added to a beaker containing carbon tetrachloride, ultrasonically dispersed for 30 minutes, and then transferred to a 100 mL single-necked flask. The product obtained in step (3) was weighed and added to the dispersion. The mixture was condensed and refluxed for 6 hours. After the reaction was completed, the product was filtered out by suction, washed with carbon tetrachloride three times, and dried in a vacuum oven to obtain an antibacterial agent.

[0046] The preparation method of the coating composite material containing an antibacterial agent is as follows:

[0047] 0.1 phr antioxidant (pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate) and 100 phr PP were fed from the main feeding port, and 1 phr of the antibacterial agent prepared above was fed from the side feeding port. The mixture was mixed and extruded in a twin-screw extruder at 180°C to obtain a coating layer composite material containing the antibacterial agent.

[0048] The preparation of the antibacterial polymer with a coating structure is carried out according to the following steps:

[0049] 20 vol% of the coating polymer containing the antibacterial agent and 80 vol% of PE were fed from the main feeding port and injected into a single screw injection molding machine at 180 ° C at a speed of 50 cm. 3 / s and mixed injection molding is performed to obtain an antibacterial polymer with a coating structure.

[0050] Example 2

[0051] The preparation method of the organic-inorganic composite antibacterial agent is as follows:

[0052] (1) Dissolve 15 g of KH560 and 85 g of ZnO in a 250 mL three-necked flask containing water and ethanol (volume ratio 1:4). Stir the mixture at 400 rpm using a magnetic stirrer for 6 h. Centrifuge the mixture at 5000 rpm and collect the precipitate. Repeat this process five times and dry the mixture for 24 h.

[0053] (2) The dried product obtained in step (1) was dissolved in a 250 mL three-necked flask filled with anhydrous ethanol, ultrasonically dispersed for 30 min, and then 5 g of cinnamaldehyde (CA) was added. The mixture was washed three times by centrifugation with anhydrous ethanol and dried for 24 h.

[0054] (3) Add 9 g of thymol (THY) to a 100 mL single-necked flask containing carbon tetrachloride to dissolve the thymol. Add 10 g of N-bromosuccinimide (NBS) and reflux under condensation for 6 h. Distill the resulting filtrate on a rotary evaporator to obtain a light yellow liquid product.

[0055] (4) The dried product obtained in step (2) was added to a beaker containing carbon tetrachloride, ultrasonically dispersed for 30 minutes, and then transferred to a 100 mL single-necked flask. The product obtained in step (3) was weighed and added to the dispersion. The mixture was condensed and refluxed for 6 hours. After the reaction was completed, the product was filtered out by suction, washed with carbon tetrachloride three times, and dried in a vacuum oven to obtain an antibacterial agent.

[0056] The preparation method of the coating composite material containing an antibacterial agent is as follows:

[0057] 1 phr antioxidant and 100 phr PA6 were fed from the main feeding port, and 20 phr of the above-prepared antibacterial agent was fed from the side feeding port, and mixed and extruded in a twin-screw extruder at 220° C. to obtain a coating layer composite material containing the antibacterial agent.

[0058] The preparation of the antibacterial polymer with a coating structure is carried out according to the following steps:

[0059] 40 vol% of the coating polymer containing the antibacterial agent and 60 vol% of PP were fed from the main feeding port and extruded in a single screw injection molding machine at 220 °C at a speed of 55 cm. 3 / s and mixed injection molding is performed to obtain an antibacterial polymer with a coating structure.

[0060] Example 3

[0061] The preparation method of the organic-inorganic composite antibacterial agent is as follows:

[0062] (1) Dissolve 10 g of KH570 and 90 g of ZnO in a 250 mL three-necked flask containing water and ethanol (volume ratio 1:4). Stir the mixture with magnetic stirring at 600 rpm for 6 h. Centrifuge the mixture at 5000 rpm and collect the precipitate. Repeat this process five times and dry the mixture for 24 h.

[0063] (2) The dried product obtained in step (1) was dissolved in a 250 mL three-necked flask filled with anhydrous ethanol, ultrasonically dispersed for 30 min, and then 5 g of cinnamaldehyde (CA) was added. The mixture was washed three times by centrifugation with anhydrous ethanol and dried for 24 h.

[0064] (3) Add 4.5 g of thymol (THY) to a 100 mL single-necked flask containing carbon tetrachloride to dissolve the thymol. Add 5 g of N-bromosuccinimide (NBS) and reflux under condensation for 6 h. Distill the resulting filtrate on a rotary evaporator to obtain a light yellow liquid product.

[0065] (4) The dried product obtained in step (2) was added to a beaker containing carbon tetrachloride, ultrasonically dispersed for 30 minutes, and then transferred to a 100 mL single-necked flask. The product obtained in step (3) was weighed and added to the dispersion. The mixture was condensed and refluxed for 6 hours. After the reaction was completed, the product was filtered out by suction, washed with carbon tetrachloride three times, and dried in a vacuum oven to obtain an antibacterial agent.

[0066] The preparation method of the coating composite material containing an antibacterial agent is as follows:

[0067] 0.4 phr antioxidant and 100 phr ABS were fed from the main feeding port, and 5 phr of the antibacterial agent prepared above was fed from the side feeding port, and mixed and extruded in a twin-screw extruder at 190° C. to obtain a coating layer composite material containing the antibacterial agent.

[0068] The preparation method of the antibacterial polymer with a coating structure is carried out according to the following steps:

[0069] 25phr of coating polymer containing antimicrobial agent and 75phr of PP were fed from the main feeding port and extruded in a single screw injection molding machine at 190℃ at a speed of 60cm. 3 / s and mixed injection molding is performed to obtain an antibacterial polymer with a coating structure.

[0070] Example 4

[0071] The preparation method of the organic-inorganic composite antibacterial agent is as follows:

[0072] (1) Dissolve 30 g of KH570 and 85 g of ZnO in a 250 mL three-necked flask containing water and ethanol (volume ratio 1:4). Stir the mixture with magnetic stirring at 800 rpm for 6 h. Centrifuge the mixture at 5000 rpm and collect the precipitate. Repeat this process five times and dry the mixture for 24 h.

[0073] (2) The dried product obtained in step (1) was dissolved in a 250 mL three-necked flask filled with anhydrous ethanol, and ultrasonically dispersed for 30 min before adding 10 g of cinnamaldehyde (CA). The product was washed three times by centrifugation with anhydrous ethanol and dried for 24 h.

[0074] (3) Add 18 g of thymol (THY) to a 100 mL single-necked flask containing carbon tetrachloride to dissolve the thymol. Add 20 g of N-bromosuccinimide (NBS) and reflux under condensation for 6 h. Distill the resulting filtrate on a rotary evaporator to obtain a light yellow liquid product.

[0075] (4) The dried product obtained in step (2) was added to a beaker containing carbon tetrachloride, ultrasonically dispersed for 30 minutes, and then transferred to a 100 mL single-necked flask. The product obtained in step (3) was weighed and added to the dispersion. The mixture was condensed and refluxed for 6 hours. After the reaction was completed, the product was filtered out by suction, washed with carbon tetrachloride three times, and dried in a vacuum oven to obtain an antibacterial agent.

[0076] The preparation method of the coating composite material containing an antibacterial agent is as follows:

[0077] 0.6 phr antioxidant and 100 phr PA6 were fed from the main feeding port, and 10 phr of the antibacterial agent prepared above was fed from the side feeding port, and mixed and extruded in a twin-screw extruder at 220° C. to obtain a coating layer composite material containing the antibacterial agent.

[0078] The preparation method of the antibacterial polymer with a coating structure is carried out according to the following steps:

[0079] 30 vol% of the coating polymer containing the antibacterial agent and 70 vol% of PE were fed from the main feeding port and extruded in a single screw injection molding machine at 220 °C at a speed of 65 cm. 3 / s and mixed injection molding is performed to obtain an antibacterial polymer with a coating structure.

[0080] Example 5

[0081] The preparation method of the organic-inorganic composite antibacterial agent is as follows:

[0082] (1) Dissolve 20 g of KH570 and 75 g of ZnO in a 250 mL three-necked flask containing water and ethanol (volume ratio 1:4). Stir the mixture with magnetic stirring at 1000 rpm for 6 h. Centrifuge the mixture at 5000 rpm and collect the precipitate. Repeat this process five times and dry the mixture for 24 h.

[0083] (2) The dried product obtained in step (1) was dissolved in a 250 mL three-necked flask filled with anhydrous ethanol, and ultrasonically dispersed for 30 min before adding 10 g of cinnamaldehyde (CA). The product was washed three times by centrifugation with anhydrous ethanol and dried for 24 h.

[0084] (3) Add 9 g of thymol (THY) to a 100 mL single-necked flask containing carbon tetrachloride to dissolve the thymol. Add 10 g of N-bromosuccinimide (NBS) and reflux under condensation for 6 h. Distill the resulting filtrate on a rotary evaporator to obtain a light yellow liquid product.

[0085] (4) The dried product obtained in step (2) was added to a beaker containing carbon tetrachloride, ultrasonically dispersed for 30 minutes, and then transferred to a 100 mL single-necked flask. The product obtained in step (3) was weighed and added to the dispersion. The mixture was condensed and refluxed for 6 hours. After the reaction was completed, the product was filtered out by suction, washed with carbon tetrachloride three times, and dried in a vacuum oven to obtain an antibacterial agent.

[0086] The preparation method of the coating composite material containing an antibacterial agent is as follows:

[0087] 0.8 phr antioxidant and 100 phr ABS were fed from the main feeding port, and 15 phr of the antibacterial agent prepared above was fed from the side feeding port, and mixed and extruded in a twin-screw extruder at 190° C. to obtain a coating layer composite material containing the antibacterial agent.

[0088] The preparation method of the antibacterial polymer with a coating structure is carried out according to the following steps:

[0089] 35 vol% of the coating polymer containing the antibacterial agent and 65 vol% of PE were fed from the main feeding port and the mixture was extruded in a single screw injection molding machine at 190 °C at a speed of 70 cm. 3 / s and mixed injection molding is performed to obtain an antibacterial polymer with a coating structure.

[0090] Comparative Example 1

[0091] The preparation method of the organic-inorganic composite antibacterial agent is as follows:

[0092] (1) Dissolve 10 g of KH570 and 90 g of ZnO in a 250 mL three-necked flask containing water and ethanol (volume ratio 1:4). Stir the mixture with magnetic stirring at 600 rpm for 6 h. Centrifuge the mixture at 5000 rpm and collect the precipitate. Repeat this process five times and dry the mixture for 24 h.

[0093] (2) The dried product obtained in step (1) was dissolved in a 250 mL three-necked flask filled with anhydrous ethanol, ultrasonically dispersed for 30 min, and then 5 g of cinnamaldehyde (CA) was added. The mixture was washed three times by centrifugation with anhydrous ethanol and dried for 24 h.

[0094] (3) Add 4.5 g of thymol (THY) to a 100 mL single-necked flask containing carbon tetrachloride to dissolve the thymol. Add 5 g of N-bromosuccinimide (NBS) and reflux under condensation for 6 h. Distill the resulting filtrate on a rotary evaporator to obtain a light yellow liquid product.

[0095] (4) The dried product obtained in step (2) was added to a beaker containing carbon tetrachloride, ultrasonically dispersed for 30 min, and then transferred to a 100 mL single-necked flask. The product obtained in step (3) was weighed and added to the dispersion. Condensation and reflux were carried out for 6 h. After the reaction was completed, the product was filtered out by suction, washed with carbon tetrachloride three times, and dried in a vacuum oven.

[0096] The preparation method of the composite material containing the antibacterial agent is as follows:

[0097] (1) 100 phr PP was fed from the main feed port, and 4 phr organic-inorganic composite antimicrobial agent was fed from the side feed port, and mixed and extruded in a twin-screw extruder at 180° C. to obtain a polypropylene composite material containing an antimicrobial agent.

[0098] (2) The coating polymer containing the antibacterial agent obtained in step (1) was fed from the feed port and injected into a single screw injection molding machine at 180°C at a speed of 50 cm 3 / s injection molding was performed to obtain an antibacterial polymer.

[0099] Comparative Example 2

[0100] The preparation method of the organic-inorganic composite antibacterial agent is as follows:

[0101] (1) Dissolve 10 g of KH570 and 90 g of ZnO in a 250 mL three-necked flask containing water and ethanol (volume ratio 1:4). Stir the mixture with magnetic stirring at 600 rpm for 6 h. Centrifuge the mixture at 5000 rpm and collect the precipitate. Repeat this process five times and dry the mixture for 24 h.

[0102] (2) The dried product obtained in step (1) was dissolved in a 250 mL three-necked flask filled with anhydrous ethanol, ultrasonically dispersed for 30 min, and then 5 g of cinnamaldehyde (CA) was added. The mixture was washed three times by centrifugation with anhydrous ethanol and dried for 24 h.

[0103] (3) Add 4.5 g of thymol (THY) to a 100 mL single-necked flask containing carbon tetrachloride to dissolve the thymol. Add 5 g of N-bromosuccinimide (NBS) and reflux under condensation for 6 h. Distill the resulting filtrate on a rotary evaporator to obtain a light yellow liquid product.

[0104] (4) The dried product obtained in step (2) was added to a beaker containing carbon tetrachloride, ultrasonically dispersed for 30 minutes, and then transferred to a 100 mL single-necked flask. The product obtained in step (3) was weighed and added to the dispersion. The mixture was condensed and refluxed for 6 hours. After the reaction was completed, the product was filtered out by suction, washed with carbon tetrachloride three times, and dried in a vacuum oven to obtain an antibacterial agent.

[0105] The preparation method of the composite material containing the antibacterial agent is as follows:

[0106] (1) 100 phr of PE was fed from the main feed port, and 4 phr of an organic-inorganic composite antimicrobial agent was fed from the side feed port, and the mixture was mixed and extruded in a twin-screw extruder at 180° C. to obtain a polypropylene composite material containing an antimicrobial agent.

[0107] (2) The polypropylene containing the antimicrobial agent obtained in step (1) was fed from the feed port and injected into a single screw injection molding machine at 180°C at a speed of 50 cm. 3 / s injection molding was performed to obtain an antibacterial polymer.

[0108] Comparative Example 3

[0109] The preparation method of the composite material containing the antibacterial agent is as follows:

[0110] (1) 100 phr PP was fed from the main feed port, and 3 phr of nano zinc oxide (ZnO) antibacterial agent was fed from the side feed port, and mixed and extruded in a twin-screw extruder at 180° C. to obtain a polypropylene composite material containing an antibacterial agent.

[0111] (2) The polypropylene material containing the antibacterial agent was fed from the main feed port and injected into a single screw injection molding machine at 180°C at a speed of 70 cm. 3 / s injection molding was performed to obtain an antibacterial polymer.

[0112] Effect embodiment

[0113] The polarity test was performed on the selected materials before preparation in the above embodiments and comparative examples:

[0114] Table 1 Polarity differences among four materials

[0115]

[0116] From the test results in Table 1, it can be seen that the non-polarity values ​​of the four materials are not much different, but the polarity values ​​are significantly different, resulting in large differences in surface tension. The four materials have obvious polarity differences, so obvious stratification will appear during the injection molding process, forming a coating structure.

[0117] Polarity tests were performed on the antimicrobial agents and coating polymers in the above examples:

[0118] Table 2 Polarity differences between antimicrobial agents and coating polymers in various embodiments

[0119]

[0120] From the test results in Table 2, it can be seen that the polarity value, non-polarity value and surface tension of the antimicrobial agents synthesized using different formulas are similar to those of the coating layer material. According to the selective distribution of inorganic particles, the antimicrobial agents tend to be distributed in the coating layer.

[0121] The shear viscosity test was performed on the selected materials before preparation in the above embodiments and comparative examples:

[0122] Table 3 Viscosity ratio of four materials

[0123]

[0124] From the test results in Table 3, it can be seen that the viscosity ratio of the four materials is greater than 1.5.

[0125] The composite materials prepared in the above examples and comparative examples were tested for mechanical properties and antibacterial properties:

[0126] Table 4 Effects of antimicrobial agents on mechanical properties and antimicrobial properties of PP materials

[0127]

[0128] The test results in Table 4 show that the tensile strength, flexural strength, impact strength, and elongation at break of the resulting composite material are only slightly lower than those of the original pure polymer material, and the mechanical properties of the composite material meet the applicable standards. This indicates that the interfacial bonding between the two materials in the resulting structure is good, with no significant phase separation.

[0129] A comparison found that the composite material with the addition of the organic-inorganic antibacterial agent O-ZnO-CT had good antibacterial properties against Staphylococcus aureus and Escherichia coli, and the antibacterial rate was improved compared with the commonly used ZnO antibacterial agent on the market.

[0130] It will be easily understood by those skilled in the art that the above description is merely an embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for preparing an antibacterial polymer with a low antibacterial agent content and a coating structure, characterized in that: The following steps are involved: (1) Using organic antimicrobial agents to modify inorganic antimicrobial agents to prepare organic-inorganic composite antimicrobial agents; The organic antibacterial agent is selected from one or more of cinnamaldehyde, thymol, carvacrol, and citral; The inorganic antibacterial agent is selected from one or more of zinc oxide and titanium dioxide; (2) melting, shearing, and mixing the organic-inorganic composite antimicrobial agent, the antioxidant, and the coating layer polymer in a twin-screw extruder to obtain a coating layer polymer composite material containing the antimicrobial agent; The coating layer polymer is selected from LDPE, HDPE, PA6 or ABS; (3) uniformly mixing the coating layer polymer composite material containing the antimicrobial agent and the core layer polymer particles, and then injection molding them in an injection molding machine to obtain the antimicrobial polymer with a low antimicrobial agent content and a coating structure; The core layer polymer particles are made of PP, PLA or PE; The difference in contact angle between the coating layer polymer composite material containing the antibacterial agent and the core layer polymer particle material is controlled within a range of 1 to 20° under a non-polar test liquid test; and within a range of 1 to 50° under a polar test liquid test; and the viscosity ratio between the coating layer polymer composite material containing the antibacterial agent and the core layer polymer particle material under the injection molding process of an injection molding machine is controlled within a range of 1.0 to 5.

0.

2. The method for preparing the antibacterial polymer with low antibacterial agent content and coating structure according to claim 1, characterized in that: In step (2), the mass ratios of the organic-inorganic composite antibacterial agent, antioxidant and coating layer polymer are 1 to 30 parts, 0.1 to 5 parts and 100 parts respectively.

3. The method for preparing the antimicrobial polymer with low antimicrobial agent content and coating structure according to claim 1, characterized in that: In step (2), the antioxidant is one or more of pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, tris[2,4-di-tert-butylphenyl]phosphite, and n-octadecylβ-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate.

4. The method for preparing the antimicrobial polymer with low antimicrobial agent content and coating structure according to claim 1, characterized in that: In step (2), the temperature range of the extruder is 160-230° C., and the rotation speed of the extruder is 50-100 rpm.

5. The method for preparing the antimicrobial polymer with low antimicrobial agent content and coating structure according to claim 1, characterized in that: In step (3), the mass ratios of the coating layer polymer composite material containing the antibacterial agent and the core layer polymer particle material are 1 to 50 parts and 50 to 99 parts respectively.

6. The method for preparing the antimicrobial polymer with low antimicrobial agent content and coating structure according to claim 1, characterized in that: In step (3), the temperature range of the injection molding machine is 160-230°C, and the injection speed of the injection molding machine is 40-90 cm 3 / s.

7. The method for preparing the antimicrobial polymer with low antimicrobial agent content and coating structure according to claim 1, characterized in that: The preparation method of the organic-inorganic composite antibacterial agent is as follows: (1) Add 10-30 parts of silane coupling agent and 75-90 parts of ZnO to a mixed solvent of water and ethanol, stir at a stirring rate of 200 r / min for 6 hours, centrifuge, and take a precipitate; replace the ZnO in the above operation with the precipitate, repeat the above operation 5 times, and dry the precipitate for use; The silane coupling agent is KH550, KH560 or KH570; (2) adding the dried product obtained in step (1) to anhydrous ethanol, ultrasonically dispersing for 30 minutes, adding 5 to 15 parts of cinnamaldehyde and mixing evenly, then centrifugally washing with anhydrous ethanol, drying, and setting aside; (3) Add 4.5 to 18 parts of thymol to carbon tetrachloride to dissolve the thymol, then add 5 to 20 parts of N-bromosuccinimide, condense and reflux, react for 6 hours, filter, and evaporate the filtrate to remove the solvent under reduced pressure to obtain a light yellow liquid product; (4) adding the dried product obtained in step (2) to carbon tetrachloride, and ultrasonically dispersing for 30 minutes to obtain a dispersion; adding the liquid product obtained in step (3) to the dispersion, condensing and refluxing, reacting for 6 hours, and then filtering, washing the filtered product with carbon tetrachloride, and vacuum drying to obtain the organic-inorganic composite antibacterial agent.

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