Preparation method of degradable PET composite material for blister packaging

Abstract

The application relates to the technical field of PET polyester, and discloses a preparation method of a degradable PET composite material for blister packaging. 100 parts by weight of polyethylene terephthalate, 1.2-4 parts by weight of a polyester quaternary ammonium salt grafted chitosan are added into a double-screw extruder, melt extruded, and cut into particles to obtain the degradable PET composite material for blister packaging. The chitosan is grafted with terephthalate polyester molecular chains, so that the compatibility between the chitosan and the PET is better, and the influence on the mechanical properties of the PET material is very small. The chitosan and the grafted polyester molecular chains are also easily biodegradable, so that the PET material has a high biodegradation rate. The polyester molecular main chain grafted with the chitosan contains a large number of quaternary ammonium salt antibacterial groups, which are matched with the chitosan, so that the inhibition and killing performance and the antibacterial rate of the PET material to escherichia coli and staphylococcus aureus are significantly improved.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of PET polyester, in particular to a preparation method of a degradable PET composite material for blister packaging. BACKGROUND

[0002] Blister packaging products have the advantages of light weight, sealing performance and the like, can package any special-shaped product, do not need to additionally add buffer materials when being packed into boxes, and are widely applied to aspects such as food packaging, medical and pharmaceutical transportation, electronic product protection and the like. The materials of the blister packaging products mainly include polyvinyl chloride, polyethylene, polystyrene, polyethylene terephthalate and the like. The polyethylene terephthalate PET has better heat resistance, high mechanical strength, is biodegradable, has small green pollution and is widely applied.

[0003] The traditional PET material does not have good antibacterial performance, which is not conducive to the practical application of the PET in aspects such as food and medical and pharmaceutical packaging. Chitosan and its derivatives are a kind of natural antibacterial agent, have good biocompatibility, are biodegradable, green and environmentally friendly, and have important application in packaging materials. The chitosan can be added into the PET and the like to improve the antibacterial and biodegradable performance of the material. The Chinese patent CN111019171B discloses that a modified silicate-aluminate doped with carboxylated chitosan is mixed with ethylene glycol to obtain a carboxylated chitosan / silicate-aluminate / ethylene glycol blend, and then is subjected to in-situ polymerization with terephthalic acid to obtain a PET modified master batch, and the obtained PET protective film has good mechanical properties and water vapor barrier properties, but the PET protective film does not exhibit excellent antibacterial performance. Generally, the antibacterial performance of the material is related to the addition amount of the chitosan, if the addition amount is small, the antibacterial performance of the material is low. The PET material exhibits high antibacterial performance by adding a small amount of chitosan and its derivatives. SUMMARY

[0004] The application solves the problem of poor antibacterial performance of a degradable PET material for blister packaging.

[0005] The technical scheme of the application is a preparation method of a degradable PET composite material for blister packaging.

[0006] (1) A reaction container is added with dimethyl sulfoxide, carboxymethyl chitosan, brominated alcohol, 4-dimethylaminopyridine and N,N-dicyclohexyl carbodiimide, and is stirred at 20-30 DEG C for 7-12 h, ethanol is added to the solution to precipitate a precipitate, the precipitate is filtered, washed with ethanol and dried to obtain brominated carboxylate chitosan. The reaction formula is as follows:

[0007] .

[0008] (2) adding N,N-dimethylformamide, bromo carboxylate chitosan, N,N,N',N'-tetramethyl ethylenediamine, bromo phthalate into a reaction container, stirring at 100-120 DEG C for 36-48h, adding ethanol into the solution to precipitate the precipitate, washing with ethanol after filtration, drying to obtain polyester quaternary ammonium salt grafted chitosan.

[0009] .

[0010] (3) adding 100 parts by weight of polyethylene terephthalate, 1.2-4 parts by weight of polyester quaternary ammonium salt grafted chitosan into a twin-screw extruder, the temperature of each section is 220 DEG C, 255 DEG C, 265 DEG C, 265 DEG C, 260 DEG C, the screw rotation speed is 30-50r / min, melt extruding, pelletizing to obtain a degradable PET composite material for blister packaging.

[0011] Preferably, the amount of carboxymethyl chitosan in (1) is 100 parts by weight, the amount of bromo alcohol is 2-6 parts by weight, the amount of 4-dimethylaminopyridine is 0.9-3.1 parts by weight, and the amount of N,N-dicyclohexyl carbodiimide is 3.3-10.8 parts by weight. The bromo alcohol is 2-bromoethanol, 3-bromopropanol or 4-bromobutanol.

[0012] Preferably, the amount of bromo carboxylate chitosan in (2) is 100 parts by weight, the amount of N,N,N',N'-tetramethyl ethylenediamine is 12-30 parts by weight, and the amount of bromo phthalate is 40-126 parts by weight.

[0013] Preferably, the preparation method of bromo phthalate is as follows: adding dichloromethane, 100 parts by weight of terephthaloyl chloride, 250-306 parts by weight of bromo alcohol, 190-220 parts by weight of triethylamine into a reaction container in an ice bath, then reacting at 20-25 DEG C for 18-24h, washing with 5% potassium carbonate solution, adding anhydrous sodium sulfate to the dichloromethane organic phase after separation, drying and removing water, filtering, rotary evaporation of the filtrate, recrystallizing the product in ethyl acetate to obtain bromo phthalate. The bromo alcohol is 2-bromoethanol, 3-bromopropanol or 4-bromobutanol. The reaction formula is as follows:

[0014] .

[0015] The application has the beneficial technical effects: esterification reaction of 2-bromoethanol and other bromo alcohols with carboxymethyl chitosan to obtain bromo carboxylate chitosan, using bromine atom as a polymerization site, quaternary ammonium grafting polymerization reaction with N,N,N',N'-tetramethyl ethylenediamine and bromo phthalate to obtain polyester quaternary ammonium salt grafted chitosan, thereby introducing polyester molecular chains containing terephthalate structural units and quaternary ammonium salt into the side chain of chitosan.

[0016] The application melts and mixes polyethylene terephthalate and polyester quaternary ammonium salt grafted chitosan to obtain a degradable PET composite material for blister packaging. The chitosan is grafted with terephthalate polyester molecular chains similar to PET, so that the compatibility between chitosan and PET is better, the mechanical property of PET material is little affected, and the impact strength of PET material is still high.

[0017] The chitosan of the application has excellent biodegradability, and the grafted polyester molecular chain is also easily biodegradable, so that the PET material has a high biodegradation rate. Moreover, the polyester molecular main chain grafted with chitosan contains a large number of quaternary ammonium salt antibacterial groups, which cooperate with chitosan, and the addition amount is only 1.5-4%, which significantly improves the inhibition and killing performance and antibacterial rate of PET material on escherichia coli and staphylococcus aureus, and exhibits stronger antibacterial performance. The prepared PET material has good practical application in blister packaging products, food packaging, medical product packaging and the like. DETAILED DESCRIPTION

[0018] Although the specific embodiments of the application are described above, the description is not a limitation on the protection scope of the application, and those skilled in the art should understand that various modifications or changes made by those skilled in the art on the basis of the technical solutions of the application without creative labor are still within the protection scope of the application.

[0019] The following carboxymethyl chitosan has an effective ingredient content of 99% and is purchased from Xi'an Tianzheng Pharmaceutical Auxiliary Material Co., Ltd. The chitosan quaternary ammonium salt has an effective ingredient content of 99% and is purchased from Xi'an Tianzheng Pharmaceutical Auxiliary Material Co., Ltd. The polyethylene terephthalate PET is purchased from Shenzhen Wanplas Source Rubber Plastic Co., Ltd.

[0020] Example 1

[0021] (1) 100 mL of dichloromethane, 20 g of terephthaloyl chloride, 50 g of 2-bromoethanol, 40 g of triethylamine were added to a reaction container, and then reacted at 20℃ for 24 h. The solution was extracted and washed with a 5% mass fraction potassium carbonate solution, and then separated. Anhydrous sodium sulfate was added to the dichloromethane organic phase, dried and water was removed, filtered, and the filtrate was rotary evaporated. The product was recrystallized in ethyl acetate to obtain brominated terephthalate. The structural formula is:

[0022] .

[0023] (2) 4 L of dimethyl sulfoxide, 200 g of carboxymethyl chitosan, 4 g of 2-bromoethanol, 1.8 g of 4-dimethylaminopyridine, and 6.6 g of N,N-dicyclohexyl carbodiimide were added to a reaction container, and then stirred and reacted at 25℃ for 7 h. Ethanol was added to the solution to precipitate the precipitate, which was filtered and washed with ethanol, and then dried to obtain brominated carboxylate chitosan.

[0024] (3) Add 2L of N,N-dimethylformamide, 100g of bromocarboxylate chitosan, 12g of N,N,N',N'-tetramethyl ethylenediamine, and 40g of bromophthalate into a reaction container, and stir at 120°C for 36h. Add ethanol to the solution to precipitate the precipitate, wash with ethanol after filtration, and dry to obtain polyester quaternary ammonium salt grafted chitosan.

[0025] (4) Add 10kg of polyethylene terephthalate and 120g of polyester quaternary ammonium salt grafted chitosan into a twin-screw extruder, and melt extrude at a screw rotation speed of 50r / min, with the temperature of each section being 220°C, 255°C, 265°C, 265°C, and 260°C. Pelletize to obtain a degradable PET composite material for blister packaging.

[0026] Example 2

[0027] (1) Add 120mL of dichloromethane, 20g of terephthaloyl chloride, 61.2g of 4-bromobutanol, and 44g of triethylamine into a reaction container, and react at 20°C for 24h. Wash with a 5% mass fraction potassium carbonate solution, separate, add anhydrous sodium sulfate to the dichloromethane organic phase, dry and remove water, filter, and rotary evaporate the filtrate. Recrystallize the product in ethyl acetate to obtain bromophthalate. The structural formula is .

[0028] (2) Add 5L of dimethyl sulfoxide, 200g of carboxymethyl chitosan, 8g of 4-bromobutanol, 4.2g of 4-dimethylaminopyridine, and 14.3g of N,N-dicyclohexyl carbodiimide into a reaction container, and stir at 20°C for 12h. Add ethanol to the solution to precipitate the precipitate, wash with ethanol after filtration, and dry to obtain bromocarboxylate chitosan.

[0029] (3) Add 2.5L of N,N-dimethylformamide, 100g of bromocarboxylate chitosan, 20g of N,N,N',N'-tetramethyl ethylenediamine, and 85g of bromophthalate into a reaction container, and stir at 100°C for 48h. Add ethanol to the solution to precipitate the precipitate, wash with ethanol after filtration, and dry to obtain polyester quaternary ammonium salt grafted chitosan.

[0030] (4) Add 10kg of polyethylene terephthalate and 250g of polyester quaternary ammonium salt grafted chitosan into a twin-screw extruder, and melt extrude at a screw rotation speed of 30r / min, with the temperature of each section being 220°C, 255°C, 265°C, 265°C, and 260°C. Pelletize to obtain a degradable PET composite material for blister packaging.

[0031] Example 3

[0032] (1) Into a reaction vessel was added 120 mL of dichloromethane, 20 g of terephthaloyl chloride, 55.8 g of 3-bromopropanol, 38 g of triethylamine, and then reacted at 25°C for 18 h. The product was extracted and washed with a 5% by mass potassium carbonate solution, and then separated. Anhydrous sodium sulfate was added to the dichloromethane organic phase, and then dried and dehydrated. The filtrate was rotary evaporated, and the product was recrystallized in ethyl acetate to obtain a brominated phthalate. The structural formula is .

[0033] (2) Into a reaction vessel was added 5 L of dimethyl sulfoxide, 200 g of carboxymethyl chitosan, 12 g of 3-bromopropanol, 6.2 g of 4-dimethylaminopyridine, and 21.6 g of N,N-dicyclohexyl carbodiimide, and then stirred and reacted at 30°C for 10 h. Ethanol was added to the solution to precipitate the product, which was filtered and washed with ethanol, and then dried to obtain a brominated carboxylate chitosan.

[0034] (3) Into a reaction vessel was added 3 L of N,N-dimethylformamide, 100 g of the brominated carboxylate chitosan, 30 g of N,N,N',N'-tetramethyl ethylenediamine, and 126 g of the brominated phthalate, and then stirred and reacted at 110°C for 48 h. Ethanol was added to the solution to precipitate the product, which was filtered and washed with ethanol, and then dried to obtain a polyester quaternary ammonium salt grafted chitosan.

[0035] (4) 10 kg of polyethylene terephthalate and 400 g of the polyester quaternary ammonium salt grafted chitosan were added to a twin-screw extruder, and then melt-extruded at 220°C, 255°C, 265°C, 265°C, and 260°C, and at a screw rotation speed of 50 r / min. The product was pelletized to obtain a degradable PET composite material for blister packaging.

[0036] Comparative Example 1

[0037] (1) 10 kg of polyethylene terephthalate was added to a twin-screw extruder, and then melt-extruded at 220°C, 255°C, 265°C, 265°C, and 260°C, and at a screw rotation speed of 50 r / min. The product was pelletized to obtain a degradable PET composite material for blister packaging.

[0038] Comparative Example 2

[0039] (1) 10 kg of polyethylene terephthalate and 120 g of carboxymethyl chitosan were added to a twin-screw extruder, and then melt-extruded at 220°C, 255°C, 265°C, 265°C, and 260°C, and at a screw rotation speed of 50 r / min. The product was pelletized to obtain a degradable PET composite material for blister packaging.

[0040] Comparative Example 3

[0041] (1) Put 10 kg of polyethylene terephthalate, 120 g of chitosan quaternary ammonium salt into a twin-screw extruder, the temperature of each section is 220℃, 255℃, 265℃, 265℃, 260℃, the screw rotation speed is 50 r / min, melt extrusion, granulation, to obtain a degradable PET composite material for blister packaging.

[0042] Comparative Example 4

[0043] (1) Put 2L of N,N-dimethylformamide, 100 g of bromine carboxylate chitosan, 12 g of N,N,N',N'-tetramethyl ethylenediamine, 19.8 g of 1,2-dibromoethane into a reaction container, stir at 120℃ for 36h, add ethanol to the solution to precipitate the precipitate, filter and wash with ethanol, and dry to obtain a polymeric quaternary ammonium salt grafted chitosan.

[0044] (2) Put 10 kg of polyethylene terephthalate, 120 g of polymeric quaternary ammonium salt grafted chitosan into a twin-screw extruder, the temperature of each section is 220℃, 255℃, 265℃, 265℃, 260℃, the screw rotation speed is 50 r / min, melt extrusion, granulation, to obtain a degradable PET composite material for blister packaging.

[0045] Comparative Example 5

[0046] (1) Put 2L of N,N-dimethylformamide, 100 g of carboxymethyl chitosan, 12 g of N,N,N',N'-tetramethyl ethylenediamine, 40 g of bromine phthalate into a reaction container, stir at 120℃ for 36h, add ethanol to the solution to precipitate the precipitate, filter and wash with ethanol, and dry to obtain a polyester quaternary ammonium salt-chitosan mixture.

[0047] (2) Put 10 kg of polyethylene terephthalate, 120 g of polyester quaternary ammonium salt-chitosan mixture into a twin-screw extruder, the temperature of each section is 220℃, 255℃, 265℃, 265℃, 260℃, the screw rotation speed is 50 r / min, melt extrusion, granulation, to obtain a degradable PET composite material for blister packaging.

[0048] The PET composite material is made into a test sample by an injection molding machine, the injection molding temperature is 265℃. The cantilever beam impact strength is tested according to the national standard GB / T 1843-2008. The biodegradation rate is tested according to the standard GB / T 19277.2-2013.

[0049] The antibacterial performance is tested according to the method of QB / T2591-2003. The test bacteria are Escherichia coli and Staphylococcus aureus. The antibacterial rate R = (B-C) / B x 100%. B is the average number of recovered bacteria (cfu / sheet) of the blank control sample (Comparative Example 1). C is the average number of recovered bacteria (cfu / sheet) of the antibacterial plastic sample.

[0050] Table 1 PET composite performance test

[0051]

[0052] As shown in Table 1, compared with the PET material of Comparative Example 1, the polyester quaternary ammonium salt grafted chitosan is added in Examples 1-3, the chitosan is grafted with polyester molecular chain similar to terephthalate group of PET, , which makes the compatibility between chitosan and PET better, and has little effect on the mechanical properties of the material. The PET material still maintains high impact strength, and the chitosan has excellent biodegradable performance, and the grafted polyester molecular chain is also easily biodegradable, so that the PET material has high biodegradation rate. At the same time, the main chain of the chitosan grafted with polyester molecular chain contains a large number of quaternary ammonium salt antibacterial groups, which cooperates with chitosan, and the addition amount is only 1.5-4%, which significantly improves the inhibition and killing performance and antibacterial rate of PET material on Escherichia coli and Staphylococcus aureus, and shows stronger antibacterial performance.

[0053] The PET material of Comparative Example 2 only adds carboxymethyl chitosan, which does not contain quaternary ammonium salt groups and has poor compatibility with PET, which will affect the mechanical properties of the material and the impact strength will decrease greatly.

[0054] Comparative Example 3 adds conventional chitosan quaternary ammonium salt, which has poor compatibility with PET and will affect the mechanical properties of the material, and the impact strength will decrease greatly.

[0055] Comparative Example 4 uses N,N,N',N'-tetramethyl ethylenediamine and 1,2-dibromoethane (not containing ester group) as raw materials to prepare polymeric quaternary ammonium salt grafted chitosan, which does not contain polyester molecular chain and has poor compatibility with PET, and the impact strength of the material decreases greatly. And the polymeric quaternary ammonium salt does not contain degradable polyester molecular chain, which will reduce the biodegradation rate of the material. However, the main chain of the chitosan grafted with polymeric quaternary ammonium salt contains a large number of quaternary ammonium salt antibacterial groups, which cooperates with chitosan, and significantly improves the antibacterial rate of PET material on Escherichia coli and Staphylococcus aureus.

[0056] The carboxymethyl chitosan of Comparative Example 5 does not contain bromine atom, which cannot be grafted with N,N,N',N'-tetramethyl ethylenediamine and bromo phthalate to carry out grafting polymerization reaction, resulting in that the chitosan does not graft polyester molecular chain, and the compatibility between chitosan and PET is poor, and the impact strength of the material decreases greatly.

Claims

1. A method for preparing a biodegradable PET composite material for blister packaging, characterized in that, The preparation method is as follows: (1) Add dimethyl sulfoxide, carboxymethyl chitosan, bromoethanol, 4-dimethylaminopyridine, and N,N-dicyclohexylcarbodiimide to the reaction vessel, stir the reaction, add ethanol to the solution to precipitate the precipitate, filter, wash, and dry to obtain bromocarboxylic acid ester chitosan. (2) Add N,N-dimethylformamide, brominated carboxylic acid ester chitosan, N,N,N',N'-tetramethylethylenediamine and brominated phthalate to the reaction vessel, stir the reaction, add ethanol to the solution to precipitate the precipitate, filter, wash and dry to obtain polyester quaternary ammonium salt grafted chitosan. The structural formula of the brominated phthalate is as follows: The R group is -CH2CH2-, -CH2CH2CH2-, or -CH2CH2CH2CH2-; (3) Add 100 parts by weight of polyethylene terephthalate and 1.2-4 parts by weight of polyester quaternary ammonium salt grafted chitosan to a twin-screw extruder, melt extrude, and granulate to obtain a biodegradable PET composite material for blister packaging.

2. The method for preparing the biodegradable PET composite material for blister packaging according to claim 1, characterized in that, The reaction temperature in (1) is 20-30℃ and the reaction time is 7-12h.

3. The method for preparing the biodegradable PET composite material for blister packaging according to claim 1, characterized in that, In (1), the amount of carboxymethyl chitosan is 100 parts by weight, the amount of bromoethanol is 2-6 parts by weight, the amount of 4-dimethylaminopyridine is 0.9-3.1 parts by weight, and the amount of N,N-dicyclohexylcarbodiimide is 3.3-10.8 parts by weight.

4. The method for preparing the biodegradable PET composite material for blister packaging according to claim 1, characterized in that, The reaction temperature in (2) is 100-120℃ and the reaction time is 36-48h.

5. The method for preparing the biodegradable PET composite material for blister packaging according to claim 1, characterized in that, In (2), the amount of bromocarboxylic acid ester chitosan is 100 parts by weight, N,N,N',N'-tetramethylethylenediamine is 12-30 parts by weight, and bromopyromellitic ester is 40-126 parts by weight.

6. The method for preparing the biodegradable PET composite material for blister packaging according to claim 1, characterized in that, The preparation method of the brominated pyromellitic ester is as follows: In an ice bath, dichloromethane, 100 parts by weight of terephthaloyl chloride, 250-306 parts by weight of bromoethanol, and 190-220 parts by weight of triethylamine are added to a reaction vessel, and then the reaction is carried out at 20-25°C for 18-24 hours. The product is extracted and washed with potassium carbonate solution, and the extracted product is recrystallized to obtain brominated pyromellitic ester.

7. The method for preparing the biodegradable PET composite material for blister packaging according to claim 3 or 6, characterized in that, The bromoethanol is 2-bromoethanol, 3-bromopropanol, or 4-bromobutanol.

8. The method for preparing the biodegradable PET composite material for blister packaging according to claim 1, characterized in that, The temperature of each section of the twin-screw extruder in (3) is 220-265℃, and the screw speed is 30-50r / min.

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