Safe antibacterial PP material and preparation method thereof

Abstract

The present application relates to the technical field of polypropylene, and discloses a safe antibacterial PP material and a preparation method, wherein the safe antibacterial PP material comprises 75-90 parts by weight of polypropylene resin, 10-25 parts by weight of crosslinked polystyrene loaded with silver ions, and 0.2-0.6 parts by weight of an antioxidant. The crosslinked polystyrene contains an aliphatic long carbon chain, and has good compatibility with polypropylene, so that the polypropylene and the polystyrene form a compatible alloy system, and the tensile strength and impact strength of the PP material are significantly improved. The crosslinked polystyrene contains Schiff base and carboxyl groups, and has strong coordination performance for silver ions, so that a large amount of silver ions are adsorbed and loaded into the crosslinked polystyrene matrix, the silver ion antibacterial agent is loaded into the crosslinked polystyrene matrix, and is uniformly dispersed in the polypropylene matrix, and the antibacterial performance of the PP material is significantly improved.

Description

Technical Field

[0001] This invention relates to the field of polypropylene technology, specifically to a safe antibacterial PP material and its preparation method. Background Technology

[0002] Polypropylene is a general-purpose engineering plastic widely used in daily necessities, furniture, home appliances, building materials, and medical supplies. However, ordinary polypropylene materials have poor antibacterial properties. Silver antibacterial agents are non-toxic, non-polluting, highly safe, have strong bactericidal properties, and broad-spectrum antibacterial activity, making them widely used in plastics and fibers. Typically, silver antibacterial agents are loaded onto carriers such as zeolites, zirconium phosphate, and molecular sieves. However, these carriers have poor compatibility with polymers like polypropylene, significantly impacting the material's mechanical properties. Using chitosan, polyacrylic acid, and coordination polymers as carriers for silver antibacterial agents offers advantages such as good processability, high stability, and strong bactericidal ability.

[0003] Polystyrene has good mechanical strength, heat resistance, and acid and alkali resistance. However, polystyrene and polypropylene have poor compatibility. Usually, it is necessary to add compatibilizers or modify polystyrene to form a compatible alloy system with polypropylene in order to obtain plastic alloy materials with better mechanical properties. Summary of the Invention

[0004] This invention solves the problem of poor antibacterial properties of polypropylene materials, while also improving the mechanical properties of polypropylene.

[0005] The technical solution of this invention is as follows: a safe antibacterial PP material and its preparation method, comprising 75-90 parts by weight of polypropylene resin, 10-25 parts by weight of cross-linked polystyrene loaded with silver ions, and 0.2-0.6 parts by weight of antioxidant; the preparation method of the safe antibacterial PP material is as follows: the polypropylene resin, cross-linked polystyrene loaded with silver ions, and antioxidant are mixed and added to a screw extruder, the temperature of zones 1-6 is 140-180℃, the screw speed is 100-200 r / min, and the mixture is co-extruded to obtain the safe antibacterial PP material.

[0006] Preferably, the preparation method of cross-linked polystyrene loaded with silver ions is as follows:

[0007] (1) Add 4-vinylbenzaldehyde, serine, and inorganic base in a ratio of 1 mol:(1-1.1 mmol):(1-1.1 mmol) to the solvent, heat to 40-60℃, stir for 3-5 h, cool, add water and hydrochloric acid solution, adjust pH to 6-6.5, filter, wash the product with water, and then add to ethanol for recrystallization to obtain carboxystyrene monomer.

[0008] (2) At -5 to 5°C, add carboxylated styrene monomer, fatty acyl chloride, and triethylamine in a ratio of 1 mol:(1-1.6) mol:(2-2.8) mol to dichloromethane. Then, stir the reaction mixture at 20-30°C for 12-18 hours. Add hydrochloric acid solution, shake to extract, concentrate the organic phase under reduced pressure, wash the product with petroleum ether, and then recrystallize it in dichloromethane to obtain fatty acid-based styrene monomer. Preparation reaction formula:

[0009]

[0010] (3) Add styrene, fatty acid-based styrene monomer, divinylbenzene and azobisisobutyronitrile to toluene, concentrate under reduced pressure after reaction, wash with dichloromethane and ethanol, and dry to obtain cross-linked polystyrene.

[0011] (4) Add water and cross-linked polystyrene to tetrahydrofuran, stir, add silver nitrate aqueous solution dropwise, stir to adsorb, filter, wash with water, and dry to obtain cross-linked polystyrene loaded with silver ions.

[0012] Furthermore, in (1), the solvent is methanol or ethanol.

[0013] Furthermore, in (1), the inorganic base is sodium hydroxide or potassium hydroxide.

[0014] Furthermore, the structural formula of the fatty acyl chloride in (2) is C n H 2n+1 COCl, where n is any one of 13-17.

[0015] Furthermore, in (3), the ratio of styrene, fatty acid-based styrene monomer, divinylbenzene, and azobisisobutyronitrile is (55-80) mol: (20-45) mol: (1.5-4) mol: (2.2-3.4) mol.

[0016] Furthermore, the reaction in (3) is stirred at 60-70℃ for 6-8 hours.

[0017] Furthermore, in (4), the ratio of cross-linked polystyrene to silver nitrate is 100g:(5-30)g.

[0018] Furthermore, in (4), the adsorption is carried out at 50-65℃ in the dark for 6-12 hours.

[0019] The beneficial technical effects of this invention are as follows: This invention involves cross-linking and copolymerizing styrene, fatty acid-based styrene monomer, and divinylbenzene to obtain cross-linked polystyrene containing aliphatic long carbon chains, Schiff bases, and carboxyl groups. After being loaded with silver ions for adsorption, it is blended and extruded with polypropylene to obtain a safe and antibacterial PP material.

[0020] The cross-linked polystyrene of this invention contains aliphatic long carbon chains, which have good compatibility with polypropylene, enabling polypropylene and polystyrene to form a compatible alloy system, which significantly improves the tensile strength and impact strength of PP materials.

[0021] The cross-linked polystyrene of this invention contains Schiff bases and carboxyl groups, which have strong coordination properties for silver ions. This allows a large number of silver ions to be adsorbed and loaded into the cross-linked polystyrene matrix. The silver ion antibacterial agent is loaded into the cross-linked polystyrene matrix and uniformly dispersed in the polypropylene matrix, which significantly improves the antibacterial properties of the PP material. Detailed Implementation

[0022] To make the technical solutions of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. It should be noted that the following embodiments are only used to better understand the technical solutions of the present invention and should not be construed as limiting the present invention.

[0023] Example 1

[0024] (1) Add 40 mmol of 4-vinylbenzaldehyde, 40 mmol of serine, and 40 mmol of sodium hydroxide to 500 mL of ethanol. Heat to 60 °C and stir for 3 h. After cooling, add 1 L of water and 5% hydrochloric acid solution to adjust the pH to 6. Filter and wash the product with water, then add it to ethanol for recrystallization to obtain a carboxystyrene monomer; the structural formula is as follows:

[0025] (2) At -5℃, 50 mmol of carboxystyrene monomer, 60 mmol of palmitoyl chloride, and 120 mmol of triethylamine were added to 150 mL of dichloromethane. The mixture was then stirred at 25℃ for 18 h. Hydrochloric acid solution was added, and the mixture was extracted by shaking. The organic phase was concentrated under reduced pressure, and the product was washed with petroleum ether. The product was then recrystallized in dichloromethane to obtain fatty acid-based styrene monomer. The structural formula is as follows:

[0026] (3) Add 80 mmol styrene, 20 mmol fatty acid styrene monomer, 2.8 mmol divinylbenzene and 2.7 mmol azobisisobutyronitrile to 120 mL toluene, stir and react at 60 °C for 8 h, concentrate under reduced pressure, wash with dichloromethane and ethanol, and dry to obtain cross-linked polystyrene.

[0027] (4) Add 1L of water and 100g of cross-linked polystyrene to 3L of tetrahydrofuran, stir, and then add 10mL of aqueous solution containing 5g of silver nitrate. Stir and adsorb at 60℃ in the dark for 6h, filter, wash with water, and dry to obtain cross-linked polystyrene loaded with silver ions.

[0028] (5) Mix 900g of polypropylene resin, 100g of cross-linked polystyrene loaded with silver ions and 6g of antioxidant 168, add them to the screw extruder, set the temperature of zones 1-6 to 140℃, 160℃, 170℃, 170℃, 180℃ and 180℃ respectively, and set the screw speed to 100r / min. Co-extrude to obtain safe antibacterial PP material.

[0029] Example 2

[0030] (1) Add 40 mmol of 4-vinylbenzaldehyde, 40 mmol of serine and 40 mmol of potassium hydroxide to 600 mL of methanol, heat to 40 °C, stir for 5 h, cool and add 1 L of water and 5% hydrochloric acid solution to adjust the pH to 6.5, filter and wash the product with water, then add to ethanol and recrystallize to obtain carboxystyrene monomer.

[0031] (2) At 5°C, 50 mmol of carboxystyrene monomer, 80 mmol of stearoyl chloride, and 140 mmol of triethylamine were added to 200 mL of dichloromethane. The mixture was then stirred at 20°C for 18 h. Hydrochloric acid solution was added, and the mixture was extracted by shaking. The organic phase was concentrated under reduced pressure, and the product was washed with petroleum ether. The product was then recrystallized from dichloromethane to obtain fatty acid-based styrene monomer. The structural formula is as follows:

[0032] (3) Add 70 mmol styrene, 30 mmol fatty acid styrene monomer, 4 mmol divinylbenzene and 2.2 mmol azobisisobutyronitrile to 150 mL toluene, stir and react at 70 °C for 8 h, concentrate under reduced pressure, wash with dichloromethane and ethanol, and dry to obtain cross-linked polystyrene.

[0033] (4) Add 1.5L of water and 100g of cross-linked polystyrene to 4L of tetrahydrofuran, stir, and then add 30mL of aqueous solution containing 15g of silver nitrate. Stir and adsorb at 50℃ in the dark for 12h, filter, wash with water, and dry to obtain cross-linked polystyrene loaded with silver ions.

[0034] (5) Mix 800g of polypropylene resin, 200g of cross-linked polystyrene loaded with silver ions and 5g of antioxidant 168, add them to the screw extruder, set the temperature of zones 1-6 to 140℃, 160℃, 170℃, 170℃, 180℃ and 180℃ respectively, and set the screw speed to 200r / min. Co-extrude to obtain safe antibacterial PP material.

[0035] Example 3

[0036] (1) Add 40 mmol of 4-vinylbenzaldehyde, 44 mmol of serine and 44 mmol of sodium hydroxide to 600 mL of ethanol, heat to 50 °C, stir for 5 h, cool and add 1.2 L of water and 8% hydrochloric acid solution to adjust the pH to 6, filter and wash the product with water, then add to ethanol and recrystallize to obtain carboxystyrene monomer.

[0037] (2) At 0°C, 50 mmol of carboxystyrene monomer, 50 mmol of myristoyl chloride, and 100 mmol of triethylamine were added to 200 mL of dichloromethane. The mixture was then stirred at 30°C for 12 h. Hydrochloric acid solution was added, and the mixture was extracted by shaking. The organic phase was concentrated under reduced pressure, and the product was washed with petroleum ether. The product was then recrystallized from dichloromethane to obtain fatty acid-based styrene monomer. The structural formula is as follows:

[0038] (3) Add 55 mmol styrene, 45 mmol fatty acid styrene monomer, 1.5 mmol divinylbenzene and 3.4 mmol azobisisobutyronitrile to 150 mL toluene, stir and react at 60 °C for 8 h, concentrate under reduced pressure, wash with dichloromethane and ethanol, and dry to obtain cross-linked polystyrene.

[0039] (4) Add 1.5L of water and 100g of cross-linked polystyrene to 4.5L of tetrahydrofuran, stir, and then add 60mL of aqueous solution containing 30g of silver nitrate. Stir and adsorb at 65℃ in the dark for 6h, filter, wash with water, and dry to obtain cross-linked polystyrene loaded with silver ions.

[0040] (5) Mix 750g of polypropylene resin, 250g of cross-linked polystyrene loaded with silver ions and 2g of antioxidant 168, add them to the screw extruder, set the temperature of zones 1-6 to 140℃, 160℃, 170℃, 170℃, 180℃ and 180℃ respectively, and set the screw speed to 200r / min. Co-extrude to obtain safe antibacterial PP material.

[0041] Comparative Example 1 differs from Example 1 in that it does not contain cross-linked polystyrene-loaded silver ions.

[0042] (1) Mix 900g of polypropylene resin and 6g of antioxidant 168 and add them to the screw extruder. The temperatures of zones 1-6 are 140℃, 160℃, 170℃, 170℃, 180℃, and 180℃, and the screw speed is 100r / min. Plug and extrude to obtain PP material.

[0043] Comparative Example 2 differs from Example 1 in that cross-linked polystyrene is used instead of cross-linked polystyrene to support silver ions.

[0044] (1) Mix 900g of polypropylene resin, 100g of cross-linked polystyrene and 6g of antioxidant 168, add them to the screw extruder, set the temperature of zones 1-6 to 140℃, 160℃, 170℃, 170℃, 180℃ and 180℃ respectively, and set the screw speed to 100r / min. Co-extrusion is carried out to obtain PP material.

[0045] The main difference between Comparative Example 3 and Example 1 is that no fatty acid-based styrene monomer is added.

[0046] (1) Add 100 mmol styrene, 2.8 mmol divinylbenzene and 2.7 mmol azobisisobutyronitrile to 120 mL toluene, stir and react at 60 °C for 8 h, concentrate under reduced pressure, wash with dichloromethane and ethanol, and dry to obtain cross-linked polystyrene.

[0047] (2) Add 1L of water and 100g of cross-linked polystyrene to 3L of tetrahydrofuran, stir, and then add 10mL of aqueous solution containing 5g of silver nitrate. Stir and adsorb at 60℃ in the dark for 6h, filter, wash with water, and dry to obtain cross-linked polystyrene loaded with silver ions.

[0048] (3) Mix 900g of polypropylene resin, 100g of cross-linked polystyrene loaded with silver ions and 6g of antioxidant 168, add them to the screw extruder, set the temperature of zones 1-6 to 140℃, 160℃, 170℃, 170℃, 180℃ and 180℃ respectively, and set the screw speed to 100r / min. Co-extrusion is carried out to obtain PP material.

[0049] Comparative Example 4 differs from Example 1 in that it uses a carboxylated styrene monomer (structural formula: It can replace fatty acid-based styrene monomers.

[0050] (1) Add 80 mmol styrene, 20 mmol carboxystyrene monomer, 2.8 mmol divinylbenzene and 2.7 mmol azobisisobutyronitrile to 120 mL toluene, stir and react at 60 °C for 8 h, concentrate under reduced pressure, wash with dichloromethane and ethanol, and dry to obtain cross-linked polystyrene.

[0051] (2) Add 1L of water and 100g of cross-linked polystyrene to 3L of tetrahydrofuran, stir, and then add 10mL of aqueous solution containing 5g of silver nitrate. Stir and adsorb at 60℃ in the dark for 6h, filter, wash with water, and dry to obtain cross-linked polystyrene loaded with silver ions.

[0052] (3) Mix 900g of polypropylene resin, 100g of cross-linked polystyrene loaded with silver ions and 6g of antioxidant 168, add them to the screw extruder, set the temperature of zones 1-6 to 140℃, 160℃, 170℃, 170℃, 180℃ and 180℃ respectively, and set the screw speed to 100r / min. Co-extrusion is carried out to obtain PP material.

[0053] Escherichia coli was used as the test strain, and the antibacterial properties of PP materials were tested according to the standard QB / T 2591-2003. The antibacterial rate W = (BC) / B × 100, where B is the average recovered bacterial count (CFU / mL) of the control group, and C is the average recovered bacterial count (CFU / mL) of the experimental sample group. The control group was the PP material of Comparative Example 1.

[0054] PP material is injection molded into standard specimens using an injection molding machine, and then its mechanical properties are tested.

[0055] The tensile strength of PP material was tested according to GB / T 1040.1-2018.

[0056] The impact strength of PP materials was tested according to the standard GB / T 1043.1-2008.

[0057] Table 1 Properties of PP materials

[0058]

[0059] After testing, compared with Comparative Example 1, the PP materials of Examples 1-3 incorporated cross-linked polystyrene loaded with silver ions. Cross-linked polystyrene contains aliphatic long carbon chains, which have good compatibility with polypropylene, forming a compatible alloy system between polypropylene and polystyrene. This significantly improved the tensile strength and impact strength of the PP material. Furthermore, cross-linked polystyrene contains Schiff bases and carboxyl groups, which have strong coordination properties for silver ions, thereby adsorbing and loading a large number of silver ions into the cross-linked polystyrene matrix. The silver ion antibacterial agent is loaded into the cross-linked polystyrene matrix and uniformly dispersed in the polypropylene matrix, significantly improving the antibacterial properties of the PP material.

[0060] Compared to Example 1, Comparative Example 2 only added cross-linked polystyrene and did not contain silver ions, resulting in poor antibacterial properties of the PP material. Comparative Example 3 did not add fatty acid-based styrene monomers, and the prepared cross-linked polystyrene did not contain aliphatic long carbon chains, leading to poor compatibility between polystyrene and polypropylene. The two were unable to form a compatible alloy system, resulting in lower tensile strength and impact strength of the PP material compared to Comparative Example 1, with a decreasing trend. Furthermore, the cross-linked polystyrene did not contain Schiff bases or carboxyl groups, resulting in weak coordination properties for silver ions. This made it difficult to adsorb and load a large amount of silver ions into the cross-linked polystyrene matrix, leading to a lower silver ion content in the cross-linked polystyrene, and a significantly lower antibacterial rate than in Example 1. Comparative Example 4 used carboxylated styrene monomers instead of fatty acid-based styrene monomers, resulting in cross-linked polystyrene that did not contain aliphatic long carbon chains. This led to poor compatibility between polystyrene and polypropylene, making it difficult to form a compatible alloy system, and the tensile strength and impact strength of the PP material were lower than in Example 1.

[0061] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A safe antibacterial PP material, characterized in that, The safe antibacterial PP material comprises 75-90 parts by weight of polypropylene resin, 10-25 parts by weight of cross-linked polystyrene loaded with silver ions, and 0.2-0.6 parts by weight of antioxidant. The method for preparing the cross-linked polystyrene-supported silver ions is as follows: S1. Add styrene, fatty acid-based styrene monomer, divinylbenzene, and azobisisobutyronitrile to toluene. After reaction, concentrate under reduced pressure, wash, and dry to obtain cross-linked polystyrene. S2. Add water and cross-linked polystyrene to tetrahydrofuran, stir, and then add an aqueous solution of silver nitrate dropwise. After stirring and adsorption, filter, wash, and dry to obtain cross-linked polystyrene loaded with silver ions. The method for preparing the fatty acid-based styrene monomer is as follows: (1) Add 4-vinylbenzaldehyde, serine, and inorganic base in a ratio of 1 mol:(1-1.1 mmol):(1-1.1 mmol) to the solvent, heat to 40-60℃, stir for 3-5 h, cool, add water and hydrochloric acid solution, adjust pH to 6-6.5, filter, wash the product, recrystallize to obtain carboxystyrene monomer. (2) At -5 to 5℃, add carboxystyrene monomer, fatty acyl chloride and triethylamine in a ratio of 1 mol:(1-1.6) mol:(2-2.8) mol to dichloromethane, then stir the reaction at 20-30℃ for 12-18 h, add hydrochloric acid solution, shake to extract, wash the product, recrystallize to obtain fatty acid styrene monomer.

2. The safe antibacterial PP material according to claim 1, characterized in that, The ratio of styrene, fatty acid-based styrene monomer, divinylbenzene, and azobisisobutyronitrile in S1 is (55-80) mol: (20-45) mol: (1.5-4) mol: (2.2-3.4) mol.

3. The safe antibacterial PP material according to claim 1, characterized in that, The reaction in S1 is stirred at 60-70℃ for 6-8 hours.

4. The safe antibacterial PP material according to claim 1, characterized in that, The ratio of cross-linked polystyrene to silver nitrate in S2 is 100g:(5-30)g.

5. The safe antibacterial PP material according to claim 1, characterized in that, The adsorption process in S2 is carried out at 50-65℃ in the dark for 6-12 hours.

6. The safe antibacterial PP material according to claim 1, characterized in that, The solvent in (1) is methanol or ethanol.

7. The safe antibacterial PP material according to claim 1, characterized in that, The inorganic base in (1) is sodium hydroxide or potassium hydroxide.

8. The safe antibacterial PP material according to claim 1, characterized in that, The structural formula of the fatty acyl chloride in (2) is C n H 2n+1 COCl, where n is any one of 13-17.

9. A method for preparing a safe antibacterial PP material as described in any one of claims 1-8, characterized in that, The preparation method is as follows: polypropylene resin, cross-linked polystyrene loaded with silver ions and antioxidant are mixed and added to a screw extruder. The temperature of zones 1-6 is 140-180℃ and the screw speed is 100-200r / min. The mixture is then co-extruded to obtain a safe antibacterial PP material.

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