Preparation process of antibacterial polypropylene material for blister packaging

Abstract

The application relates to the technical field of polypropylene, and discloses a preparation process of antibacterial polypropylene material for blister packaging, which comprises the following steps: reacting hexamethylene diisocyanate, 2,2'-diamino-N-methyl diethylamine and 1-chloro-3-(cashew phenol)oxy-2-propanol to obtain a quaternary ammonium cashew phenol copolymer; and adding 100 parts by weight of polypropylene resin, 4-8 parts by weight of the quaternary ammonium cashew phenol copolymer and the like into a double-screw extruder, melt-extruding and cutting to obtain the antibacterial polypropylene material for blister packaging. The quaternary ammonium cashew phenol copolymer contains hydrophilic urea groups, hydroxyl groups and quaternary ammonium salt groups, which are beneficial to improving the hydrophilicity of the polypropylene, improving the antistatic property and improving the impact strength. Moreover, the antibacterial quaternary ammonium salt groups contained in the quaternary ammonium cashew phenol copolymer make the polypropylene material exhibit excellent antibacterial performance, which is beneficial to expanding the practical application of the polypropylene in antibacterial packaging materials for food and medicines.

Description

Technical Field

[0001] This invention relates to the field of polypropylene technology, specifically to a preparation process for an antibacterial polypropylene material for blister packaging. Background Technology

[0002] Blister packaging products are widely used in the packaging and transportation of food, pharmaceuticals, and health products. The main materials used in blister packaging include polypropylene, polyvinyl chloride (PVC), and polyethylene terephthalate (PET). Polypropylene, in particular, is widely used due to its advantages such as being non-toxic, odorless, transparent, low-density, and lightweight. However, traditional polypropylene and its blister packaging products suffer from poor antibacterial and antistatic properties, which hinders their practical application in food and pharmaceutical packaging.

[0003] Antibacterial agents for polypropylene mainly include nano-silver, nano-titanium dioxide, and quaternary ammonium salts. Organic quaternary ammonium salt antibacterial agents have good compatibility with polymer resins, are inexpensive, and have diverse preparation methods, making them a high-performance organic antibacterial agent. Chinese patent CN112281309B discloses an antibacterial radiation-proof nonwoven fabric and its preparation method. It utilizes the conductivity of silicon carbide fibers and the antistatic properties of modified methylcellulose, while simultaneously using hexadecyl ether and trimethylammonium chloride to protonate the hydroxyl groups on the surface of bacterial cellulose, introducing quaternary ammonium salt groups or alkyl chain groups, thus giving the polypropylene nonwoven fabric good antistatic and antibacterial properties. However, the raw materials in this patent are relatively complex, and it does not improve the mechanical properties of the polypropylene product. Cashew nut shell oil is a natural compound extracted from cashew nut shell oil. It is inexpensive, readily available, biocompatible, and has strong high-temperature resistance. It can be made into toughening agents, emulsifiers, antibacterial agents, etc., and has important applications in polymer materials such as polypropylene, polyethylene, and epoxy resins. Summary of the Invention

[0004] This invention solves the problem of poor antibacterial and antistatic properties of antibacterial polypropylene materials used in blister packaging.

[0005] The technical solution of this invention: A preparation process for an antibacterial polypropylene material for blister packaging:

[0006] (1) Add solvent, hexamethylene diisocyanate (CAS Registry No. 822-06-0), and 2,2'-diamino-N-methyldiethylamine (CAS Registry No. 4097-88-5) to a reaction vessel equipped with a reflux condenser. Stir at 45-70°C for 2-4 hours to carry out the polymerization reaction. Remove the solvent by vacuum distillation, wash with ethanol, and dry to obtain tertiary amine polyurea copolymer.

[0007] (2) N,N-dimethylformamide, tertiary amine polyurea copolymer, and 1-chloro-3-(cainol)oxy-2-propanol were added to a reaction vessel and stirred at 100-130℃ for 18-36 h. N,N-dimethylformamide was removed by vacuum distillation, followed by washing with dichloromethane and drying to obtain the quaternized cashew phenol copolymer. The reaction formula is as follows:

[0008]

[0009] In the reaction formula, n is 25-31.

[0010] (3) Add 100 parts by weight of polypropylene resin, 4-8 parts by weight of quaternized cashew phenol copolymer and 0.2-0.4 parts by weight of antioxidant into a twin-screw extruder, melt extrude and granulate to obtain antibacterial polypropylene material for blister packaging.

[0011] Preferably, the solvent in (1) is dichloromethane, tetrahydrofuran, toluene or N,N-dimethylformamide.

[0012] Preferably, in (1), the amount of hexamethylene diisocyanate is 100 parts by weight, and the amount of 2,2'-diamino-N-methyldiethylamine is 65-75 parts by weight.

[0013] Preferably, (2) the amount of tertiary amine polyurea copolymer is 100 parts by weight and 1-chloro-3-(cashewol)oxy-2-propanol is 80-140 parts by weight.

[0014] Preferably, in (3), the temperature of each section of the twin-screw extruder is 150-190℃ and the screw speed is 40-80r / min.

[0015] Preferably, the antioxidant in (3) is a hindered phenolic antioxidant or a phosphite antioxidant.

[0016] The technical effects of this invention are as follows: Hexamethylene diisocyanate and 2,2'-diamino-N-methyldiethylamine are polymerized to obtain a tertiary amine polyurea copolymer. The tertiary amine group then undergoes a quaternization reaction with the chlorine atom of 1-chloro-3-(cainol)oxy-2-propanol to obtain a quaternized cashew nut copolymer. Finally, this copolymer is melt-blended with polypropylene to obtain an antibacterial polypropylene material for blister packaging. The main chain of this quaternized cashew nut copolymer contains urea hydrophilic groups, while the side chains contain hydrophilic hydroxyl and quaternary ammonium salt groups. Adding it to polypropylene improves the hydrophilicity of the polypropylene, allowing it to adsorb moisture from the air and form a conductive water molecule film on the surface, thereby reducing surface resistivity and improving antistatic properties.

[0017] The side chains of the quaternized cashew phenol copolymer of this invention contain antibacterial quaternary ammonium salt groups, which can effectively kill and inhibit bacteria and microorganisms, giving the polypropylene material excellent antibacterial properties. This is beneficial for expanding the practical application of polypropylene in antibacterial packaging materials for food, pharmaceuticals, and other products.

[0018] The quaternized cashew phenol copolymer of the present invention contains a large number of long cashew phenol alkyl chains in its side chains, which have good compatibility with polypropylene and have little impact on the mechanical properties of polypropylene when added to it. At the same time, the large number of long alkyl chains form physical entanglement with the polypropylene molecular chains, which can improve the degree of crosslinking between polypropylene molecular chains and is beneficial to improving impact strength and mechanical properties. Detailed Implementation

[0019] While the specific embodiments of the present invention have been described above, they are not intended to limit the scope of protection of the present invention. Those skilled in the art should understand that various modifications or variations that can be made by those skilled in the art without creative effort based on the technical solutions of the present invention are still within the scope of protection of the present invention.

[0020] The following polypropylene resin, model Yuanye 990, was purchased from Maoming Yuanye Plastic Products Co., Ltd.

[0021] 1-Chloro-3-(Cashewol)oxy-2-propanol was prepared according to the method described in the article "Process Technology Research of Cashew Phenolic Glycidyl Ether" published in the journal *Henan Chemical Industry*, Vol. 30, 2013. 3 g (approximately 10 mmol) of cashew phenol, 50 mmol of epichlorohydrin, and 0.06 g of benzyltriethylammonium chloride catalyst were added to a reaction vessel. The reaction was carried out at 80 °C for 4 h. After dilution with water, the mixture was extracted and washed with dichloromethane. After separation, the organic phase of dichloromethane was distilled under reduced pressure and separated by column chromatography. The eluent was a solution of petroleum ether and ethyl acetate in a volume ratio of 10:1, yielding 1-chloro-3-(cashewol)oxy-2-propanol. The structural formula is as follows: n is 25-31.

[0022] Bromocainol ether was prepared according to the method described in the graduate thesis "Synthesis and Antibacterial Properties of Quaternized Cashew Phenol" published by Tianjin University of Technology. 25 mL of isopropanol, 1.17 g (6.25 mmol) of 1,2-dibromoethane, and 3.45 g (25 mmol) of potassium carbonate were added to a reaction vessel equipped with a reflux condenser. Then, 10 mL of isopropanol solution containing 0.3 g (approximately 1 mmol) of cashew phenol was added dropwise. The reaction was carried out at 90 °C for 12 h. After filtration, the filtrate was distilled under reduced pressure and separated by column chromatography. The eluent was a 10:1 (v / v) solution of petroleum ether and ethyl acetate to obtain the bromocainol ether. The structural formula is: n is 27-31.

[0023] Example 1

[0024] (1) Add 200 mL of tetrahydrofuran, 40 g of hexamethylene diisocyanate and 28 g of 2,2'-diamino-N-methyldiethylamine to a reaction vessel equipped with a reflux condenser. Stir at 60 °C for 3 h to carry out the polymerization reaction. Remove the solvent by vacuum distillation, wash with ethanol and dry to obtain tertiary amine polyurea copolymer.

[0025] (2) Add 300 mL of N,N-dimethylformamide, 50 g of tertiary amine polyurea copolymer and 55 g of 1-chloro-3-(cainol)oxy-2-propanol to the reaction vessel, stir and react at 100 °C for 36 h, remove N,N-dimethylformamide by vacuum distillation, wash with dichloromethane, and dry to obtain quaternized cashew phenol copolymer.

[0026] (3) 10 kg of polypropylene resin, 400 g of quaternized cashew phenol copolymer and 40 g of hindered phenolic antioxidant 1010 were added to a twin-screw extruder. The temperatures of each section were 150℃, 175℃, 190℃, 190℃ and 185℃, and the screw speed was 50 r / min. The mixture was melt-extruded and pelletized to obtain antibacterial polypropylene material for blister packaging.

[0027] Example 2

[0028] (1) Add 300 mL of dichloromethane, 40 g of hexamethylene diisocyanate and 26 g of 2,2'-diamino-N-methyldiethylamine to a reaction vessel equipped with a reflux condenser. Stir at 40 °C for 4 h to carry out the polymerization reaction. Remove the solvent by vacuum distillation, wash with ethanol and dry to obtain tertiary amine polyurea copolymer.

[0029] (2) Add 400 mL of N,N-dimethylformamide, 50 g of tertiary amine polyurea copolymer and 70 g of 1-chloro-3-(cainol)oxy-2-propanol to the reaction vessel, stir and react at 120 °C for 24 h, remove N,N-dimethylformamide by vacuum distillation, wash with dichloromethane, and dry to obtain quaternized cashew phenol copolymer.

[0030] (3) 10 kg of polypropylene resin, 500 g of quaternized cashew phenol copolymer and 28 g of phosphite antioxidant 168 were added to a twin-screw extruder. The temperatures of each section were 150℃, 175℃, 190℃, 190℃ and 185℃, and the screw speed was 80 r / min. The mixture was melt-extruded and pelletized to obtain antibacterial polypropylene material for blister packaging.

[0031] Example 3

[0032] (1) Add 200 mL of N,N-dimethylformamide, 40 g of hexamethylene diisocyanate and 28 g of 2,2'-diamino-N-methyldiethylamine to a reaction vessel equipped with a reflux condenser. Stir at 70 °C for 2 h to carry out the polymerization reaction. Remove the solvent by vacuum distillation, wash with ethanol, and dry to obtain tertiary amine polyurea copolymer.

[0033] (2) Add 300 mL of N,N-dimethylformamide, 50 g of tertiary amine polyurea copolymer and 40 g of 1-chloro-3-(cainol)oxy-2-propanol to the reaction vessel, stir and react at 120 °C for 24 h, remove N,N-dimethylformamide by vacuum distillation, wash with dichloromethane, and dry to obtain quaternized cashew phenol copolymer.

[0034] (3) 10 kg of polypropylene resin, 650 g of quaternized cashew phenol copolymer and 30 g of phosphite antioxidant 168 were added to a twin-screw extruder. The temperatures of each section were 150℃, 175℃, 190℃, 190℃ and 185℃, and the screw speed was 80 r / min. The mixture was melt-extruded and pelletized to obtain antibacterial polypropylene material for blister packaging.

[0035] Example 4

[0036] (1) Add 200 mL of toluene, 40 g of hexamethylene diisocyanate and 30 g of 2,2'-diamino-N-methyldiethylamine to a reaction vessel equipped with a reflux condenser. Stir at 65 °C for 3 h to carry out the polymerization reaction. Remove the solvent by vacuum distillation, wash with ethanol and dry to obtain tertiary amine polyurea copolymer.

[0037] (2) Add 400 mL of N,N-dimethylformamide, 50 g of tertiary amine polyurea copolymer and 55 g of 1-chloro-3-(cainol)oxy-2-propanol to the reaction vessel, stir and react at 130 °C for 18 h, remove N,N-dimethylformamide by vacuum distillation, wash with dichloromethane, and dry to obtain quaternized cashew phenol copolymer.

[0038] (3) 10 kg of polypropylene resin, 800 g of quaternized cashew phenol copolymer and 40 g of hindered phenolic antioxidant 1010 were added to a twin-screw extruder. The temperatures of each section were 150℃, 175℃, 190℃, 190℃ and 185℃, and the screw speed was 40 r / min. The mixture was melt-extruded and pelletized to obtain antibacterial polypropylene material for blister packaging.

[0039] Comparative Example 1

[0040] (1) Add 10kg of polypropylene resin and 40g of hindered phenolic antioxidant 1010 to a twin-screw extruder. The temperatures of each section are 150℃, 175℃, 190℃, 190℃ and 185℃, and the screw speed is 50r / min. Melt extrusion and pelletizing are performed to obtain polypropylene material for blister packaging.

[0041] Comparative Example 2

[0042] (1) 10 kg of polypropylene resin, 400 g of tertiary amine polyurea copolymer (prepared from Example 1) and 40 g of hindered phenolic antioxidant 1010 were added to a twin-screw extruder. The temperatures of each section were 150°C, 175°C, 190°C, 190°C and 185°C, and the screw speed was 50 r / min. The mixture was melt-extruded and pelletized to obtain polypropylene material for blister packaging.

[0043] Comparative Example 3

[0044] (1) Add 300 mL of N,N-dimethylformamide, 50 g of tertiary amine polyurea copolymer (prepared from Example 1) and 55 g of benzyl chloride to the reaction vessel. Stir the reaction at 100 °C for 36 h. Remove N,N-dimethylformamide by vacuum distillation. Wash with dichloromethane and dry to obtain quaternized copolymer.

[0045] (2) 10 kg of polypropylene resin, 400 g of quaternized copolymer and 40 g of hindered phenolic antioxidant 1010 were added to a twin-screw extruder. The temperatures of each section were 150℃, 175℃, 190℃, 190℃ and 185℃, and the screw speed was 50 r / min. The mixture was melt-extruded and pelletized to obtain antibacterial polypropylene material for blister packaging.

[0046] Comparative Example 4

[0047] (1) Add 300 mL of N,N-dimethylformamide, 50 g of tertiary amine polyurea copolymer (prepared from Example 1) and 55 g of brominated cashew ether to the reaction vessel, stir and react at 100 °C for 36 h, remove N,N-dimethylformamide by vacuum distillation, wash with dichloromethane, and dry to obtain quaternized cashew ether copolymer.

[0048] (2) 10 kg of polypropylene resin, 400 g of quaternized cashew phenol copolymer and 40 g of hindered phenolic antioxidant 1010 were added to a twin-screw extruder. The temperatures of each section were 150℃, 175℃, 190℃, 190℃ and 185℃, and the screw speed was 50 r / min. The mixture was melt-extruded and pelletized to obtain antibacterial polypropylene material for blister packaging.

[0049] Polypropylene material was injection molded into samples at an injection temperature of 210℃.

[0050] The impact strength of the simply supported beam specimen was tested according to the method in GB T1043-1-2008.

[0051] The surface resistivity of the sample was measured using a high-resistivity meter. The test temperature was 25℃ and the relative humidity was 50%.

[0052] Antimicrobial properties were tested according to QB / T2591-2003. The test bacteria were *Escherichia coli* and *Staphylococcus aureus*. The antimicrobial rate R = (BC) / B × 100%. B is the average recovered bacterial count (cfu / tablet) of the blank control sample (Comparative Example 1). C is the average recovered bacterial count (cfu / tablet) of the antimicrobial plastic sample.

[0053] Table 1. Polypropylene Material Performance Tests

[0054]

[0055]

[0056] After testing, compared with Comparative Example 1, the polypropylene materials of Examples 1-4 showed lower surface resistivity, which is beneficial to improving the antistatic properties of the materials. They also exhibited excellent antibacterial properties against Escherichia coli and Staphylococcus aureus, mainly because the main chain of the added quaternized cashew nut copolymer contains urea groups. The copolymer contains hydrophilic groups, and its side chains also contain hydrophilic hydroxyl and quaternary ammonium salt groups. Adding these to polypropylene enhances its hydrophilicity, allowing it to absorb moisture from the air and form a conductive water molecule film on its surface. This reduces surface resistivity and improves antistatic properties. Furthermore, the copolymer side chains contain antibacterial quaternary ammonium salt groups, effectively killing and inhibiting bacteria and microorganisms, exhibiting excellent antibacterial properties. The copolymer side chains contain a large number of cashew phenol alkyl long chains, which have good compatibility with polypropylene. Their addition to polypropylene has minimal impact on its mechanical properties; the impact strength of Example 1 is very similar to that of Comparative Example 1. Simultaneously, the numerous alkyl long chains form physical entanglement with the polypropylene molecular chains, increasing the cross-linking degree between polypropylene molecular chains and improving mechanical properties. The polypropylene materials of Examples 2-3 exhibit even better impact strength.

[0057] Compared to Comparative Example 2, which only added tertiary amine polyurea copolymer, lacking hydrophilic quaternary ammonium salts and hydroxyl groups, the polypropylene material exhibited lower hydrophilicity than Example 1, higher surface resistivity, and poor antistatic effect. Furthermore, it did not improve the antibacterial properties of the polypropylene material. Additionally, the tertiary amine polyurea copolymer's side chains lacked alkyl long chains, resulting in poor compatibility with polypropylene and a significant decrease in the material's impact strength.

[0058] Comparative Example 3 utilizes the chlorine atoms of conventional benzyl chloride to quaternize the tertiary amine groups of a tertiary amine polyurea copolymer. The resulting quaternized polymer lacks hydrophilic hydroxyl groups, leading to lower hydrophilicity of the polypropylene material compared to Example 1, higher surface resistivity, and poor antistatic effect. Furthermore, the side chains of the quaternized polymer do not contain long alkyl chains, resulting in poor compatibility with polypropylene and a significant decrease in the material's impact strength.

[0059] Comparative Example 4 utilizes the bromine atoms of conventional brominated cashew ether to quaternize the tertiary amine groups of the tertiary amine polyurea copolymer. The resulting quaternized cashew ether copolymer does not contain hydrophilic hydroxyl groups, which leads to the polypropylene material having lower hydrophilicity than Example 1, higher surface resistivity, and poor antistatic effect.

Claims

1. A preparation process for an antibacterial polypropylene material for blister packaging, characterized in that, The preparation process is as follows: (1) Add N,N-dimethylformamide, tertiary amine polyurea copolymer and 1-chloro-3-(cainol)oxy-2-propanol to the reaction vessel, stir the reaction, distill under reduced pressure, wash and dry to obtain quaternized cashew phenol copolymer. (2) 100 parts by weight of polypropylene resin, 4-8 parts by weight of quaternized cashew phenol copolymer and 0.2-0.4 parts by weight of antioxidant are added to a twin-screw extruder, melt extruded and pelletized to obtain antibacterial polypropylene material for blister packaging; The preparation process of the tertiary amine polyurea copolymer is as follows: a solvent, hexamethylene diisocyanate, and 2,2'-diamino-N-methyldiethylamine are added to a reaction vessel to carry out a polymerization reaction, followed by vacuum distillation, washing, and drying to obtain the tertiary amine polyurea copolymer. The amount of hexamethylene diisocyanate is 100 parts by weight, and the amount of 2,2'-diamino-N-methyldiethylamine is 65-75 parts by weight.

2. The preparation process of the antibacterial polypropylene material for blister packaging according to claim 1, characterized in that, The reaction temperature in (1) is 100-130℃ and the reaction time is 18-36h.

3. The preparation process of the antibacterial polypropylene material for blister packaging according to claim 1, characterized in that, The amount of tertiary amine polyurea copolymer used in (1) is 100 parts by weight, and the amount of 1-chloro-3-(cashewol)oxy-2-propanol is 80-140 parts by weight.

4. The preparation process of the antibacterial polypropylene material for blister packaging according to claim 1, characterized in that, The solvent is dichloromethane, tetrahydrofuran, toluene, or N,N-dimethylformamide.

5. The preparation process of the antibacterial polypropylene material for blister packaging according to claim 1, characterized in that, The polymerization reaction is carried out at a temperature of 45-70℃ for 2-4 hours.

6. The preparation process of the antibacterial polypropylene material for blister packaging according to claim 1, characterized in that, The temperature of each section of the twin-screw extruder in (2) is 150-190℃, and the screw speed is 40-80r / min.

7. The preparation process of the antibacterial polypropylene material for blister packaging according to claim 1, characterized in that, The antioxidant in (2) is a hindered phenolic antioxidant or a phosphite antioxidant.

Images