Safe antibacterial PP material and preparation method thereof

Abstract

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

Description

Technical Field

[0001] The present invention relates to the technical field of polypropylene, and specifically relates to a safe antibacterial PP material and a preparation method thereof. Background Art

[0002] Polypropylene is a general engineering plastic, which is widely used in daily necessities, furniture and household appliances, building materials, medical supplies, etc. However, the antibacterial performance of ordinary polypropylene materials is not good. Silver antibacterial agents are non-toxic, pollution-free, have high safety, strong bactericidal performance, and good antibacterial broad-spectrum properties, and are widely used in materials such as plastics and fibers. Usually, carriers such as zeolites, zirconium phosphates, and molecular sieves are required to load silver antibacterial agents, but the compatibility of these carriers with high molecular resins such as polypropylene is poor, which has a greater impact on the mechanical properties and other properties of the materials. Using high molecular polymers such as chitosan, polyacrylic acid, and coordination polymers as carriers of silver antibacterial agents has the advantages of good processing performance, high stability, and strong bactericidal ability.

[0003] Polystyrene has good mechanical strength, heat resistance, acid and alkali resistance and other properties, but the compatibility between polystyrene and polypropylene is poor. Usually, methods such as adding compatibilizers and modifying polystyrene are required to form a compatible alloy system between polystyrene and polypropylene in order to obtain a plastic alloy material with better mechanical properties. Summary of the Invention

[0004] The present invention solves the problem of poor antibacterial performance of polypropylene materials and improves the mechanical properties of polypropylene at the same time.

[0005] The technical solution of the present invention: A safe antibacterial PP material and a preparation method thereof, including 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: mixing polypropylene resin, cross-linked polystyrene loaded with silver ions, and antioxidant, adding them to a screw extruder, the temperature of zones 1-6 is 140-180 °C, the screw speed is 100-200 r / min, and co-extrusion is carried out to obtain the safe antibacterial PP material.

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

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

[0008] (2) In the range of -5 to 5 °C, carboxystyrene monomer, fatty acyl chloride, and triethylamine in a ratio of 1 mol : (1 - 1.6) mol : (2 - 2.8) mol are added to dichloromethane, and then stirred and reacted at 20 - 30 °C for 12 - 18 h. Hydrochloric acid solution is added, shaken and extracted, the organic phase is concentrated under reduced pressure, the product is washed with petroleum ether, and then recrystallized in dichloromethane to obtain fatty acid-based styrene monomer. Preparation reaction formula:

[0009]

[0010] (3) Styrene, fatty acid-based styrene monomer, divinylbenzene, and azobisisobutyronitrile are added to toluene. After the reaction, it is concentrated under reduced pressure, washed with dichloromethane and ethanol, and dried to obtain crosslinked polystyrene.

[0011] (4) Water and crosslinked polystyrene are added to tetrahydrofuran. After stirring, an aqueous solution of silver nitrate is added dropwise. After stirring and adsorption, it is filtered, washed with water, and dried to obtain crosslinked 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, in (2), the structural formula of the fatty acyl chloride 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, in (3), the reaction is stirred at 60 - 70 °C for 6 - 8 h.

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

[0018] Furthermore, in (4), the stirring and adsorption are carried out at 50 - 65 °C in the dark for 6 - 12 h.

[0019] The beneficial technical effects of the present invention: The present invention conducts a crosslinking copolymerization reaction of styrene, fatty acid-based styrene monomer, and divinylbenzene to obtain crosslinked polystyrene containing long aliphatic carbon chains, Schiff bases, and carboxyl groups. After adsorbing and loading silver ions, it is melt-blended with polypropylene to obtain a safe antibacterial PP material.

[0020] The cross-linked polystyrene of the present invention contains aliphatic long carbon chains and has good compatibility with polypropylene, enabling polypropylene and polystyrene to form a compatible alloy system, significantly improving the tensile strength and impact strength of the PP material.

[0021] The cross-linked polystyrene of the present invention contains Schiff base and carboxyl groups and has strong coordination performance for silver ions, thereby adsorbing and loading a large amount of silver ions onto 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 performance of the PP material. Specific Embodiments

[0022] To make the technical solutions of the present invention clearer, the technical solutions in the embodiments of the present invention will be described clearly and completely 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 a limitation of 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, stir and react for 3 h. After cooling, add 1 L of water and a hydrochloric acid solution with a mass fraction of 5%, adjust the pH to 6, filter, wash the product with water, then add it to ethanol for recrystallization to obtain the carboxystyrene monomer; the structural formula is

[0025] (2) At -5 °C, add 50 mmol of carboxystyrene monomer, 60 mmol of palmitoyl chloride, and 120 mmol of triethylamine to 150 mL of dichloromethane, then stir and react at 25 °C for 18 h. Add a hydrochloric acid solution, shake and extract. The organic phase is concentrated under reduced pressure, the product is washed with petroleum ether, and then added to dichloromethane for recrystallization to obtain the fatty acid-based styrene monomer. The structural formula is

[0026] (3) Add 80 mmol of styrene, 20 mmol of fatty acid-based styrene monomer, 2.8 mmol of divinylbenzene, and 2.7 mmol of azobisisobutyronitrile to 120 mL of 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 1 L of water and 100 g of cross-linked polystyrene to 3 L of tetrahydrofuran, stir, and then dropwise add 10 mL of an aqueous solution containing 5 g of silver nitrate. Stir and adsorb at 60 °C in the dark for 6 h, filter, wash with water, and dry to obtain cross-linked polystyrene loaded with silver ions.

[0028] (5) Mix 900 g of polypropylene resin, 100 g of cross-linked polystyrene loaded with silver ions, and 6 g of antioxidant 168, add them to a screw extruder. The temperatures of zones 1 - 6 are 140 °C, 160 °C, 170 °C, 170 °C, 180 °C, and 180 °C, and the screw speed is 100 r / min. Blend and extrude to obtain a 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 and react for 5 h. After cooling, add 1 L of water and a hydrochloric acid solution with a mass fraction of 5%, adjust the pH to 6.5, filter the product, wash it with water, and then add it to ethanol for recrystallization to obtain the carboxyl styrene monomer.

[0031] (2) At 5 °C, add 50 mmol of carboxyl styrene monomer, 80 mmol of stearoyl chloride, and 140 mmol of triethylamine to 200 mL of dichloromethane, then stir and react at 20 °C for 18 h. Add a hydrochloric acid solution, shake and extract. Concentrate the organic phase under reduced pressure, wash the product with petroleum ether, and then add it to dichloromethane for recrystallization to obtain the fatty acid-based styrene monomer. The structural formula is

[0032] (3) Add 70 mmol of styrene, 30 mmol of fatty acid-based styrene monomer, 4 mmol of divinylbenzene, and 2.2 mmol of azobisisobutyronitrile to 150 mL of 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 1.5 L of water and 100 g of cross-linked polystyrene to 4 L of tetrahydrofuran, stir, and then dropwise add 30 mL of an aqueous solution containing 15 g of silver nitrate. Stir and adsorb at 50 °C in the dark for 12 h, filter, wash with water, and dry to obtain cross-linked polystyrene loaded with silver ions.

[0034] (5) Mix 800 g of polypropylene resin, 200 g of cross-linked polystyrene loaded with silver ions, and 5 g of antioxidant 168, add them to a screw extruder. The temperatures of zones 1 - 6 are 140 °C, 160 °C, 170 °C, 170 °C, 180 °C, and 180 °C, and the screw speed is 200 r / min. Blend and extrude to obtain a 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 and stir for 5 h. After cooling, add 1.2 L of water and a hydrochloric acid solution with a mass fraction of 8%. Adjust the pH to 6. Filter the product and wash it with water. Then add it to ethanol for recrystallization to obtain the carboxystyrene monomer.

[0037] (2) At 0 °C, add 50 mmol of carboxystyrene monomer, 50 mmol of myristoyl chloride, and 100 mmol of triethylamine to 200 mL of dichloromethane. Then stir and react at 30 °C for 12 h. Add a hydrochloric acid solution, shake and extract. Concentrate the organic phase under reduced pressure. Wash the product with petroleum ether. Then add it to dichloromethane for recrystallization to obtain the fatty acid-based styrene monomer. The structural formula is

[0038] (3) Add 55 mmol of styrene, 45 mmol of fatty acid-based styrene monomer, 1.5 mmol of divinylbenzene, and 3.4 mmol of azobisisobutyronitrile to 150 mL of toluene. Stir and react at 60 °C for 8 h. Concentrate under reduced pressure. Wash with dichloromethane and ethanol, and dry to obtain crosslinked polystyrene.

[0039] (4) Add 1.5 L of water and 100 g of crosslinked polystyrene to 4.5 L of tetrahydrofuran. After stirring, dropwise add an aqueous solution containing 30 g of silver nitrate in 60 mL. Stir and adsorb at 65 °C in the dark for 6 h. Filter, wash with water, and dry to obtain crosslinked polystyrene loaded with silver ions.

[0040] (5) Mix 750 g of polypropylene resin, 250 g of crosslinked polystyrene loaded with silver ions, and 2 g of antioxidant 168. Add them to a screw extruder. The temperatures in zones 1 - 6 are 140 °C, 160 °C, 170 °C, 170 °C, 180 °C, 180 °C, and the screw speed is 200 r / min. Blend and extrude to obtain the safe antibacterial PP material.

[0041] Comparative Example 1, the difference from Example 1 is that crosslinked polystyrene loaded with silver ions is not added.

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

[0043] Comparative Example 2, the difference from Example 1 is that crosslinked polystyrene is used instead of crosslinked polystyrene loaded with silver ions.

[0044] (1) Mix 900 g of polypropylene resin, 100 g of crosslinked polystyrene, and 6 g of antioxidant 168, add them to a screw extruder. The temperatures of zones 1 - 6 are 140 °C, 160 °C, 170 °C, 170 °C, 180 °C, and 180 °C, and the screw speed is 100 r / min. Carry out melt blending extrusion to obtain the PP material.

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

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

[0047] (2) Add 1 L of water and 100 g of crosslinked polystyrene to 3 L of tetrahydrofuran. After stirring, dropwise add 10 mL of an aqueous solution containing 5 g of silver nitrate. Stir and adsorb at 60 °C in the dark for 6 h, filter, wash with water, and dry to obtain crosslinked polystyrene loaded with silver ions.

[0048] (3) Mix 900 g of polypropylene resin, 100 g of crosslinked polystyrene loaded with silver ions, and 6 g of antioxidant 168, add them to a screw extruder. The temperatures of zones 1 - 6 are 140 °C, 160 °C, 170 °C, 170 °C, 180 °C, and 180 °C, and the screw speed is 100 r / min. Carry out melt blending extrusion to obtain the PP material.

[0049] Comparative Example 4. The difference from Example 1 is that a carboxyl styrene monomer (structural formula is ) is used instead of the fatty acid-based styrene monomer.

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

[0051] (2) Add 1 L of water and 100 g of crosslinked polystyrene to 3 L of tetrahydrofuran. After stirring, dropwise add 10 mL of an aqueous solution containing 5 g of silver nitrate. Stir and adsorb at 60 °C in the dark for 6 h, filter, wash with water, and dry to obtain crosslinked polystyrene loaded with silver ions.

[0052] (3) Mix 900 g of polypropylene resin, 100 g of crosslinked polystyrene loaded with silver ions, and 6 g of antioxidant 168, add them to a screw extruder. The temperatures of zones 1 - 6 are 140 °C, 160 °C, 170 °C, 170 °C, 180 °C, and 180 °C, and the screw speed is 100 r / min. Carry out melt blending extrusion to obtain the PP material.

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

[0054] The PP material was injection-molded into standard splines by an injection molding machine for mechanical property testing.

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

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

[0057] Table 1 Properties of PP Materials

[0058]

[0059] After testing, compared with Comparative Example 1, cross-linked polystyrene loaded with silver ions was added to the PP materials of Examples 1-3. The cross-linked polystyrene contains long aliphatic carbon chains and has good compatibility with polypropylene, enabling polypropylene and polystyrene to form a compatible alloy system, significantly improving the tensile strength and impact strength of the PP material. Moreover, the cross-linked polystyrene contains Schiff base and carboxyl groups, which have strong coordination properties for silver ions, thereby adsorbing and loading a large amount of silver ions onto the cross-linked polystyrene matrix. The silver ion antibacterial agent is loaded onto the cross-linked polystyrene matrix and uniformly dispersed in the polypropylene matrix, significantly improving the antibacterial performance of the PP material.

[0060] Compared with Example 1, in Comparative Example 2, only cross-linked polystyrene was added and it does not contain silver ions, resulting in poor antibacterial performance of the PP material. In Comparative Example 3, fatty acid-based styrene monomer was not added, and the prepared cross-linked polystyrene does not contain long aliphatic carbon chains, leading to poor compatibility between polystyrene and polypropylene, and it is difficult for them to form a compatible alloy system, resulting in a lower tensile strength of the PP material and an impact strength lower than that of Comparative Example 1 with a downward trend. Also, the cross-linked polystyrene does not contain Schiff base and carboxyl groups, and has weak coordination properties for silver ions, making it difficult to adsorb and load a large amount of silver ions onto the cross-linked polystyrene matrix, resulting in a small amount of silver ions loaded on the cross-linked polystyrene, and the antibacterial rate of the PP material is significantly lower than that of Example 1. In Comparative Example 4, carboxyl styrene monomer was used instead of fatty acid-based styrene monomer, and the resulting cross-linked polystyrene does not contain long aliphatic carbon chains, leading to poor compatibility between polystyrene and polypropylene, and it is difficult for them to form a compatible alloy system, and the tensile strength and impact strength of the PP material are lower than those of Example 1.

[0061] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that the technical solutions of the present invention can be modified or equivalently replaced without departing from the spirit and scope of the technical solutions of the present invention, and all of them should be covered by the scope of the claims of the present invention.

Claims

1. A safe antibacterial PP material, characterized in that, The described 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 preparation method of the cross-linked polystyrene loaded with silver ions is as follows: S1. Add styrene, fatty acid-based styrene monomer, divinylbenzene, and azobisisobutyronitrile into toluene, react and then concentrate under reduced pressure, wash, and dry to obtain cross-linked polystyrene; S2. Add water and cross-linked polystyrene into tetrahydrofuran, stir and then dropwise add an aqueous solution of silver nitrate, stir for adsorption and then filter, wash, and dry to obtain cross-linked polystyrene loaded with silver ions.

2. The safety antibacterial PP material according to claim 1, characterized in that, In the said S1, 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.

3. The safe antibacterial PP material according to claim 1, wherein In the said S1, the reaction is carried out with stirring at 60 - 70 °C for 6 - 8 h.

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

5. The safety antibacterial PP material according to claim 1, characterized in that, In the said S2, the stirring for adsorption is carried out at 50 - 65 °C in the dark for 6 - 12 h.

6. The safe antibacterial PP material according to claim 1, characterized in that, The preparation method of the fatty acid-based styrene monomer in (2) 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) into a solvent, heat to 40 - 60 °C, stir and react for 3 - 5 h, cool and then add water and hydrochloric acid solution, adjust the pH to 6 - 6.5, filter and then wash the product, and recrystallize to obtain carboxyl styrene monomer; (2) At -5 to 5 °C, add carboxyl styrene monomer, fatty acyl chloride, and triethylamine in a ratio of 1 mol : (1 - 1.6) mol : (2 - 2.8) mol into dichloromethane, then stir and react at 20 - 30 °C for 12 - 18 h, add hydrochloric acid solution, oscillate and extract, wash the product, and recrystallize to obtain fatty acid-based styrene monomer.

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

8. The safe antibacterial PP material according to claim 6, characterized in that, In (1), the inorganic base is sodium hydroxide or potassium hydroxide.

9. The safe antibacterial PP material according to claim 6, wherein 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.

10. A method for preparing a safe antibacterial PP material according to any one of claims 1-9, characterized in that, The preparation method is as follows: Mix polypropylene resin, cross-linked polystyrene loaded with silver ions, and antioxidant, add them into a screw extruder, the temperature of zones 1 - 6 is 140 - 180 °C, the screw speed is 100 - 200 r / min, and carry out co-extrusion to obtain the safe antibacterial PP material.

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