Preparation method of antibacterial polyurethane adhesive based on waste PET alcoholysis product

Abstract

The application belongs to the technical field of waste PET recycling, and discloses a preparation method of an antibacterial polyurethane adhesive based on waste PET alcoholysis products. The method comprises the following steps: mixing 15-30 parts by weight of diisocyanate, 30-80 parts by weight of polyester polyol, 1-5 parts by weight of waste PET alcoholysis product terephthalic acid diethylene glycol ester and 0.3-0.7 parts by weight of a catalyst, reacting at 80-100 DEG C for 1-2 hours, cooling to 60-80 DEG C, adding 5-15 parts by weight of a chain extender, and reacting; in the reaction process, a diluent is added to obtain a hydroxyl-terminated polyurethane prepolymer; cooling to 40-55 DEG C, uniformly mixing 5-15 parts by weight of a blocked isocyanate curing agent and 40-80 parts by weight of a CS@Ag dispersion liquid to obtain the antibacterial polyurethane adhesive. The method is simple, realizes waste PET recycling, and improves the antibacterial performance and bonding performance of the polyurethane adhesive.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of waste PET recycling, and relates to a preparation method of an antibacterial polyurethane adhesive, in particular to a preparation method of an antibacterial polyurethane adhesive prepared from alcoholysis products of waste PET. BACKGROUND

[0002] With the development of industrialization, plastics have become an important material that cannot be dispensed with, and are widely used in various industrial departments such as packaging, construction, transportation and electronic industry. Polyethylene terephthalate (PET) has excellent chemical and physical properties, and is widely used, and its production is large. However, with the large use of PET, the consumption of petroleum resources is huge, and PET is chemically stable and difficult to degrade in the natural environment, which has a great impact on natural resources and environmental ecological problems, so waste PET recycling has great significance.

[0003] The recycling of waste PET mainly includes physical recycling and chemical recycling. The physical recycling has low investment cost, simple operation and large recycling amount, and the technology is relatively mature, but impurities are difficult to remove, and the regenerated product is degraded. Chemical recycling is to depolymerize PET molecular chains into monomers or oligomers, such as terephthalic acid (TPA), dimethyl terephthalate (DMT), bis(hydroxyethyl) terephthalate (BHET), ethylene glycol (EG) and the like, and then the depolymerization products are purified and used as chemical raw materials to synthesize epoxy resin, polyester resin, polyurethane and other high value-added products. Chemical recycling can realize true recycling through closed loop and upgrading recycling. The ethylene glycol alcoholysis method is one of the most commonly used PET chemical recycling methods in the industry, and the obtained waste PET alcoholysis products contain active primary hydroxyl groups at both ends, which can be applied to the synthesis of polyurethane materials to realize recycling.

[0004] Polyurethane has excellent performance and is widely used. Polyurethane adhesive, as one of the eight synthetic adhesives, has good bonding performance, low temperature resistance and other characteristics, and various product types, and plays an important role in the fields of construction, manufacturing, packaging and the like. With the gradual development of polyurethane adhesive, polyurethane adhesive with good bonding performance and antibacterial performance has a more extensive application prospect. At present, the antibacterial modification of polyurethane is mainly through physical modification, chemical modification or composite modification method, and the antibacterial agent with antibacterial groups is introduced into the polyurethane material. Through the addition of the antibacterial agent, the antibacterial effect of the polyurethane can be effectively improved, however, the antibacterial polyurethane adhesive not only needs to have good antibacterial ability, but also needs to maintain good bonding effect to meet the most basic use requirements of the adhesive. However, the research on the antibacterial and bonding effects of polyurethane adhesive is relatively less at present, which means that there is a great research space in the antibacterial polyurethane adhesive. SUMMARY

[0005] The application aims to provide a preparation method of an antibacterial polyurethane adhesive based on alcoholysis products of waste PET.

[0006] The application achieves high-value recycling of waste PET, meets the requirements of polyurethane adhesives with good antibacterial and bonding properties, and has good development prospects.

[0007] A preparation method of an antibacterial polyurethane adhesive based on alcoholysis products of waste PET, comprising the following steps:

[0008] 1) Alcoholysis of waste PET: under a protective atmosphere, waste PET and an alcoholysis agent are reacted at 170-200 DEG C for 3-5 h under the action of a catalyst, and the alcoholysis product terephthalic acid diethylene glycol ester BHET is obtained after subsequent treatment; the alcoholysis agent is ethylene glycol;

[0009] 2) Preparation of CS@Ag dispersion: disperse chitosan (CS) in water to obtain a chitosan dispersion; mix the chitosan dispersion with an aqueous silver nitrate solution, add a reducing agent, wash, dry, and obtain a CS@Ag hybrid material; the reducing agent is L-ascorbic acid, used in the form of an aqueous solution; the drying is vacuum freeze-drying; disperse the CS@Ag hybrid material in an organic solvent to obtain a CS@Ag dispersion; the reaction time is 0.5-1 h;

[0010] 3) Preparation of an antibacterial polyurethane adhesive: mix 15-30 parts by weight of diisocyanate, 30-80 parts by weight of polyester polyol, 1-5 parts by weight of alcoholysis product terephthalic acid diethylene glycol ester, and 0.3-0.7 parts by weight of catalyst, react at 80-100 DEG C for 1-2 h, then cool to 60-80 DEG C, add 5-15 parts by weight of chain extender, and react for 2-3 h to obtain a hydroxyl-terminated polyurethane prepolymer; add 4-8 parts by weight of diluent to reduce the viscosity during the reaction; cool to 40-55 DEG C, mix the hydroxyl-terminated polyurethane prepolymer, 5-15 parts by weight of a blocked isocyanate curing agent, and 40-80 parts by weight of the CS@Ag dispersion uniformly to obtain an antibacterial polyurethane adhesive.

[0011] The CS@Ag dispersion contains 10-30 parts by weight of CS@Ag and 30-50 parts by weight of organic solvent.

[0012] The polyester polyol is one or more of polyadipic acid-1,4-butanediol, polyadipic acid-1,6-hexanediol, polyadipic acid glycol ester, polyadipic acid propylene glycol ester;

[0013] The molecular weight of the polyester polyol is 1000-3000.

[0014] The diisocyanate is one or more of isophorone diisocyanate, hexamethylene diisocyanate, diphenyl diisocyanate, toluene diisocyanate.

[0015] The mass ratio of the waste PET and the alcoholysis agent in step 1) is 1:(4-7); the amount of the catalyst is 5-7% of the mass of the waste PET;

[0016] The catalyst in step 1) includes one or more of zinc acetate, magnesium acetate, sodium carbonate.

[0017] The subsequent treatment in step 1) refers to filtering after the reaction, cooling and crystallization, washing the crystals with water, and vacuum drying to obtain the alcoholysis product, terephthalic acid diethylene glycol ester.

[0018] The mass ratio of chitosan, silver nitrate and the reducing agent in step 2) is 20:(0.5-3):(0.5-3).

[0019] The concentration of the chitosan dispersion liquid in step 2) is 0.03 g / mL; the concentration of the silver nitrate aqueous solution is 2-6 wt%; and the concentration of the reducing agent aqueous solution is 1-4 wt%.

[0020] The reducing agent in step 2) is one or more of L-ascorbic acid, sodium citrate.

[0021] The organic solvent in step 2) is one or more of N,N-dimethylformamide, N-methylpyrrolidone, butanone.

[0022] The catalyst in step 3) is dibutyltin dilaurate; the chain extender is one or more of trimethylolpropane, triethanolamine, 1,4-butanediol, ethylene glycol; and the diluent includes one or more of acetone, N,N-dimethylformamide, N-methylpyrrolidone, butanone.

[0023] The blocked isocyanate curing agent in step 3) is one or more of blocked hexamethylene diisocyanate trimer curing agent, blocked isophorone diisocyanate trimer curing agent, blocked toluene diisocyanate trimer curing agent.

[0024] The present application has the following advantages:

[0025] (1) Compared with the physical recycling method, the chemical recycling method of PET can obtain higher value-added products through closed loop and upgrading recycling, realize real recycling, and has greater advantages in sustainable development.

[0026] (2) The alcoholysis product is introduced into the synthesis of polyurethane in the application, the bonding strength and tensile strength of the polyurethane adhesive are improved, and the polyurethane adhesive can be used to produce high-performance products.

[0027] (3) The chitosan hybrid material is introduced into the polyurethane in the application, the antibacterial performance and bonding performance of the polyurethane adhesive are significantly improved, and the application of the polyurethane adhesive is expanded. BRIEF DESCRIPTION OF DRAWINGS

[0028] Figure 1 The bonding performance test result graph of the adhesive prepared for example 2, comparative example 1 and comparative example 2;

[0029] Figure 2 The mechanical property test result graph of the adhesive prepared for example 2, comparative example 1 and comparative example 2;

[0030] Figure 3 The bonding performance test result graph of the adhesive prepared for example 3, comparative example 3 and comparative example 4;

[0031] Figure 4 The mechanical property test result graph of the adhesive prepared for example 3, comparative example 3 and comparative example 4. DETAILED DESCRIPTION

[0032] The application will be further described in detail below in combination with specific embodiments, but the embodiments of the application are not limited thereto.

[0033] The bonding strength of the antibacterial polyurethane adhesive is tested according to the standard GB / T 7124-2008, the bonding substrate is aluminum sheet-aluminum sheet, the adhesive is cured at 130 DEG C for 1h after coating, and the bonding strength is obtained after testing on a computerized tensile testing machine at room temperature after placing for 1 day, and the tensile rate is 5mm / min.

[0034] The tensile strength of the antibacterial polyurethane adhesive film is tested according to the standard GB / T 1040.3-2006, and the antibacterial polyurethane adhesive film is obtained by placing the antibacterial polyurethane adhesive in a polytetrafluoroethylene mold and curing at 130 DEG C for 1h.

[0035] The antibacterial rate of the antibacterial polyurethane adhesive is tested by the plate counting method, and escherichia coli and staphylococcus aureus are used as experimental bacteria.

[0036] Example 1

[0037] (1) The waste PET and alcoholysis agent were mixed and added into the reaction container at a mass ratio of 1:5 and 6wt% (6% of the mass of PET) of catalyst, maintained in a nitrogen atmosphere, reacted at 190℃ for 4h, and the product was filtered, cooled and crystallized, washed and dried to obtain bis(hydroxyethyl) terephthalate (BHET).

[0038] (2) 20g of chitosan (CS) was dispersed in deionized water (the concentration of the chitosan dispersion was 0.03g / mL) by vigorous stirring, 35mL of an aqueous silver nitrate solution (the concentration was 2wt%) was added, stirred for 0.5h, then 35mL of an aqueous L-ascorbic acid solution (the concentration was 1.5wt%) was added, and after the reaction was fully carried out (the reaction time was 0.5h), centrifugal washing was carried out several times, vacuum freeze-drying (vacuum drying at -10℃ for 24h) was carried out, and CS@Ag hybrid material was obtained. 10 parts by weight of the CS@Ag hybrid material was dispersed in 50 parts by weight of N,N-dimethylformamide, and ultrasonic treatment was carried out for 20min to obtain a CS@Ag dispersion, which was ready for use.

[0039] (3) 20 parts by weight of hexamethylene diisocyanate, 70 parts by weight of polyhexanedioic acid-1,6-hexanediol, 5 parts by weight of alcoholysis product bis(hydroxyethyl) terephthalate, and 0.3 parts by weight of catalyst dibutyltin dilaurate were mixed and reacted at 90℃ for 1h, then cooled to 70℃, 8 parts by weight of chain extender triethanolamine was added, and reacted for 3h to obtain a hydroxyl-terminated polyurethane prepolymer. 5 parts by weight of butanone was added during the reaction to reduce the viscosity.

[0040] (4) The temperature was lowered to 50℃, 15 parts by weight of blocked isophorone diisocyanate trimer curing agent was added to the polyurethane prepolymer of step (3), and the CS@Ag dispersion prepared in step (2) was added, stirred at a speed of 600rpm for 30min to obtain an antibacterial polyurethane adhesive.

[0041] The polyurethane adhesive obtained thereby had a bonding strength of 8.79MPa, an antibacterial rate of 75.0% against Escherichia coli, and an antibacterial rate of 70% against Staphylococcus aureus.

[0042] Example 2

[0043] (1) The waste PET and alcoholysis agent were mixed and added into the reaction container at a mass ratio of 1:5 and 6wt% (6% of the mass of PET) of catalyst, maintained in a nitrogen atmosphere, reacted at 190℃ for 4h, and the product was filtered, cooled and crystallized, washed and dried to obtain bis(hydroxyethyl) terephthalate (BHET).

[0044] (2) 20 g of chitosan (CS) was dispersed in deionized water by vigorous stirring, 35 mL of silver nitrate aqueous solution (concentration of 2.5 wt%) was added, stirred for 0.5 h, then 35 mL of L-ascorbic acid aqueous solution (concentration of 1.5 wt%) was added, reacted for 0.5 h, then centrifuged and washed several times, vacuum freeze-dried at -5℃ for 24 h to obtain CS@Ag hybrid material, 20 parts by weight of CS@Ag hybrid material was dispersed in 50 parts by weight of N, N-dimethylformamide, and ultrasonic treatment was performed to obtain a CS@Ag dispersion solution, which was prepared for use.

[0045] (3) 25 parts by weight of isophorone diisocyanate, 75 parts by weight of polybutylene adipate, 2 parts by weight of alcoholysis product terephthalic acid diethylene glycol ester, and 0.5 parts by weight of catalyst dibutyltin dilaurate were mixed and reacted at 90℃ for 1 h, then cooled to 70℃, 10 parts by weight of chain extender trimethylolpropane was added and reacted for 2 h to obtain a hydroxyl-terminated polyurethane prepolymer, and 5 parts by weight of butanone was added during the reaction to reduce the viscosity.

[0046] (4) The temperature was lowered to 50℃, 10 parts by weight of a blocked isocyanate curing agent was added to the polyurethane prepolymer of step (3), and the CS@Ag dispersion solution prepared in step (2) was added, and stirred at a speed of 650 rpm for 30 min to obtain an antibacterial polyurethane adhesive.

[0047] The polyurethane adhesive thus obtained has a bonding strength of 8.72 MPa, an antibacterial rate of 90.5% against Escherichia coli, and an antibacterial rate of 85.5% against Staphylococcus aureus.

[0048] Example 3

[0049] (1) Waste PET and alcoholysis agent were mixed in a mass ratio of 1:6 and 7 wt% (7% of the mass of PET) of catalyst was added to the reaction container, maintained in a nitrogen atmosphere, and reacted at 195℃ for 3 h. The product was filtered, cooled and crystallized, washed and dried to obtain terephthalic acid diethylene glycol ester (BHET).

[0050] (2) 20 g of chitosan (CS) was dispersed in deionized water by vigorous stirring, 35 mL of silver nitrate aqueous solution (concentration of 2.5 wt%) was added, stirred for 0.5 h, then 35 mL of L-ascorbic acid aqueous solution (concentration of 1.5 wt%) was added, reacted for 0.5 h, then centrifuged and washed several times, vacuum freeze-dried at -5℃ for 24 h to obtain CS@Ag hybrid material, 20 parts by weight of CS@Ag hybrid material was dispersed in 50 parts by weight of N, N-dimethylformamide, and ultrasonic treatment was performed to obtain a CS@Ag dispersion solution, which was prepared for use.

[0051] (3) 30 parts by weight of diphenyl diisocyanate, 65 parts by weight of polyethylene glycol adipate, 3 parts by weight of alcoholysis product diethylene glycol terephthalate, and 0.6 parts by weight of catalyst dibutyl tin dilaurate were mixed, reacted at 90°C for 1 h, then cooled to 70°C, 10 parts by weight of chain extender trimethylolpropane was added, and reacted for 2 h to obtain a hydroxyl-terminated polyurethane prepolymer. A diluent of 5 parts by weight of butanone was added during the reaction to reduce the viscosity.

[0052] (4) The temperature was lowered to 50°C, 15 parts by weight of a blocked isocyanate curing agent was added to the polyurethane prepolymer of step (3), and the CS@Ag dispersion of step (2) was added, stirred at a speed of 650 rpm for 30 min to obtain an antibacterial polyurethane adhesive.

[0053] The obtained polyurethane adhesive had a bonding strength of 8.00 MPa, an antibacterial rate of 94.9% against Escherichia coli, and an antibacterial rate of 82.5% against Staphylococcus aureus.

[0054] Comparative Example 1

[0055] BHET and CS@Ag were not added, and other conditions were the same as in Example 2.

[0056] Comparative Example 2

[0057] BHET was added but CS@Ag was not added, and other conditions were the same as in Example 2.

[0058] The adhesives prepared in Example 2, Comparative Example 1, and Comparative Example 2 were tested for bonding performance and mechanical properties, and the test results are shown in Tables Figure 1 and Figure 2 As can be seen from Tables Figure 1 and Figure 2 , the addition of BHET and CS@Ag can improve the bonding strength and tensile strength of the adhesive.

[0059] Comparative Example 3

[0060] 29 parts by weight of CS was used instead of CS@Ag, and other conditions were the same as in Example 3.

[0061] Comparative Example 4

[0062] Step (2): 35 mL of an aqueous solution of silver nitrate (concentration of 3 wt%) was added to 35 mL of an aqueous solution of L-ascorbic acid (concentration of 1.8 wt%), and after the reaction was complete, the mixture was centrifuged and washed several times, then freeze-dried to obtain Ag material. 1 part by weight of the Ag material was dispersed in 50 parts by weight of N-methyl pyrrolidone, and ultrasonic treatment was performed to obtain an Ag dispersion, which was ready for use.

[0063] Other steps were the same as in Example 3.

[0064] The adhesives prepared in Example 3, the adhesive prepared in Comparative Example 3, and the adhesive prepared in Comparative Example 4 were subjected to bonding performance and mechanical property tests, and the test results are shown in Tables 1-2, respectively. Figure 3 and Figure 4 It can be seen from Tables 1-2 that CS and Ag can play a synergistic role, and CS@Ag can improve the bonding strength and tensile strength of the adhesive. Figure 3 and Figure 4 It can be seen from Tables 1-2 that CS and Ag can play a synergistic role, and CS@Ag can improve the bonding strength and tensile strength of the adhesive.

Claims

1. A method for preparing an antibacterial polyurethane adhesive based on waste PET alcoholysis product, characterized by: It comprises the following steps: 1) alcoholysis of waste PET: under a protective atmosphere, waste PET and alcoholysis agent are reacted under the action of a catalyst at 170-200 DEG C for 3-5 h, followed by subsequent treatment, to obtain alcoholysis product bis(2-hydroxyethyl) terephthalate BHET; the alcoholysis agent is ethylene glycol; 2) preparation of CS@Ag dispersion: chitosan is dispersed in water to obtain a chitosan dispersion; the chitosan dispersion is mixed with an aqueous silver nitrate solution, a reducing agent is added and reacted, washed, and dried to obtain a CS@Ag hybrid material; the CS@Ag hybrid material is dispersed in an organic solvent to obtain a CS@Ag dispersion; 3) preparation of antibacterial polyurethane adhesive: 15-30 parts by weight of diisocyanate, 30-80 parts by weight of polyester polyol, 1-5 parts by weight of alcoholysis product bis(2-hydroxyethyl) terephthalate, and 0.3-0.7 parts by weight of catalyst are mixed and reacted at 80-100 DEG C for 1-2 h, then cooled to 60-80 DEG C, 5-15 parts by weight of chain extender is added and reacted for 2-3 h to obtain a hydroxyl-terminated polyurethane prepolymer, 4-8 parts by weight of diluent is added during the reaction to reduce the viscosity; cooled to 40-55 DEG C, the hydroxyl-terminated polyurethane prepolymer, 5-15 parts by weight of blocked isocyanate curing agent, and 40-80 parts by weight of CS@Ag dispersion are mixed uniformly to obtain an antibacterial polyurethane adhesive; The CS@Ag dispersion contains 10-30 parts by weight of CS@Ag and 30-50 parts by weight of organic solvent; The polyester polyol is one or more of polyhexanedioic acid-1,4-butanediol, polyhexanedioic acid-1,6-hexanediol, polyethylene glycol terephthalate, and polypropylene glycol terephthalate; the molecular weight of the polyester polyol is 1000-3000; The mass ratio of chitosan, silver nitrate, and reducing agent in step 2) is 20:(0.5-3):(0.5-3); The reducing agent in step 2) is one or more of L-ascorbic acid and sodium citrate; The diisocyanate is one or more of isophorone diisocyanate, hexamethylene diisocyanate, diphenyl diisocyanate, and toluene diisocyanate; The organic solvent in step 2) is one or more of N,N-dimethylformamide, N-methylpyrrolidone, and butanone; The blocked isocyanate curing agent in step 3) is one or more of blocked hexamethylene diisocyanate trimer curing agent, blocked isophorone diisocyanate trimer curing agent, and blocked toluene diisocyanate trimer curing agent; The catalyst in step 3) is dibutyltin dilaurate; the chain extender is one or more of trimethylolpropane, triethanolamine, 1,4-butanediol, and ethylene glycol; the diluent includes one or more of acetone, N,N-dimethylformamide, N-methylpyrrolidone, and butanone.

2. The preparation method of the antibacterial polyurethane adhesive based on waste PET alcoholysis product according to claim 1, characterized in that: The concentration of the chitosan dispersion solution in step 2) is 0.03 g / mL; the concentration of the silver nitrate aqueous solution is 2-6 wt%; the reducing agent is used in the form of an aqueous solution, and the concentration of the reducing agent aqueous solution is 1-4 wt%.

3. The method for preparing the antibacterial polyurethane adhesive based on the alcoholysis product of waste PET according to claim 1, characterized in that: The mass ratio of the waste PET and the alcoholysis agent in step 1) is 1:(4-7); the amount of the catalyst is 5-7% of the mass of the waste PET; The catalyst in step 1) comprises one or more of zinc acetate, magnesium acetate and sodium carbonate.

4. The method for preparing the antibacterial polyurethane adhesive based on the alcoholysis product of waste PET according to claim 1, characterized in that: The subsequent treatment in step 1) refers to filtering after the reaction, cooling and crystallization, washing the crystals with water, and vacuum drying to obtain the alcoholysis product, diethylene glycol terephthalate BHET; The drying in step 2) is vacuum freeze drying; and the reaction time is 0.5-1 h.

5. An antibacterial polyurethane adhesive based on the alcoholysis product of waste PET, which is prepared by the method of any one of claims 1-4.

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