Gallic acid-based polyurethane film and preparation thereof

Abstract

The bio-based degradable polyurethane film is prepared by taking gallic acid extracted from plants such as rheum palmatum, ammonium macrophyllum and the like as a base material. Polyester polyol and diisocyanate are used as raw materials, plant extract gallic acid is added to serve as a chain extender, a polyurethane solution is successfully prepared in a nitrogen environment through an oil bath pan at the temperature of 80 DEG C by adopting a two-step method, and the polyurethane solution is put into a drying oven after being subjected to tape casting in a mold and dried at the temperature of 70 DEG C to form a film. The synthesized polyurethane is mainly prepared from the following components in percentage by mass: 9.46 to 10.33 percent of polyester polyol, 3.39 to 4.11 percent of diisocyanate, 0.28 to 0.42 percent of bio-based chain extender, 0.03 to 0.05 percent of catalyst and 85.95 to 85.97 percent of organic solvent. The polyurethane film provided by the invention has ultraviolet light transmission shielding capability, excellent tensile property and degradability. The method for preparing the polyurethane film is simple and easy to operate and has low requirements on equipment.

Description

Technical Field

[0001] The invention relates to a method for preparing a gallic acid-based polyurethane film. Background Art

[0002] Polyurethanes are versatile materials whose unique mechanical, physical, biological, and chemical properties have attracted considerable research attention to tailor polyurethanes for diverse applications. Polyurethanes are typically synthesized through a prepolymerization process using polyols, diisocyanates, and chain extenders. However, the raw materials used in polyurethane synthesis are mostly derived from non-renewable petroleum resources, and the use and recycling of these resources have significantly inhibited the development of polyurethanes. Traditional chain extenders are typically derived from fossil fuels such as 1,4-butanediol and 1,6-hexanediol. Gallic acid (GA), also known as "gallic acid," is a naturally occurring phenolic compound containing three hydroxyl groups. GA is widely found in plants such as Rheum palmatum and Ammonium truncatum. It is a naturally occurring polyphenol containing three hydroxyl groups. Because its molecular structure contains three phenolic hydroxyl groups and one carboxyl group, and the phenolic hydroxyl groups can provide active hydrogen to react with -NCO, it can be used to prepare bio-based cross-linked polyurethanes. Summary of the Invention

[0003] The present invention provides a polyurethane film using a plant extract as a chain extender and a process for preparing the same. Furthermore, in comparison with polyurethane films prepared using 1,4-butanediol (BDO) as a chain extender, polyurethane films prepared using gallic acid as a chain extender exhibit greater hydrophobicity, superior tensile properties, and superior gas and moisture barrier properties compared to polyurethane films containing the same amount of BDO. These films also offer UV protection and are biodegradable.

[0004] The technical solution adopted by the present invention to solve the technical problem is:

[0005] A gallic acid-based polyurethane film, the components and mass percentages of which are:

[0006] Polyester polyol 9.46~10.33%,

[0007] Diisocyanate 3.39% to 4.11%,

[0008] Chain extender 0.28%~0.42%,

[0009] Catalyst 0.03%~0.05%,

[0010] Organic solvent 85.95%~85.98%.

[0011] Moreover, the gallic acid-based polyurethane film is prepared as follows:

[0012] (1) Raw material pretreatment: Before the reaction, place the polyester polyol, chain extender, and required instruments in a vacuum oven at 90°C-100°C and dry for 2 hours; place the diisocyanate in a refrigerator for 24 hours in advance, set the temperature to 0°C;

[0013] (2) Reaction process: The BPU film was prepared by a two-step reaction. A 250 ml round-bottom three-necked flask connected to a mechanical stirrer, a condenser, and a nitrogen inlet and outlet was used as the reaction vessel for polyurethane synthesis. The water bath temperature was raised to 80 °C for preheating in advance, and nitrogen was introduced to remove the air in the round-bottom three-necked flask. A certain amount of polyester polyol was added to the three-necked flask and the stirring rod speed was adjusted to 100 r / min. The measured diisocyanate was added dropwise using a constant pressure funnel. After a period of reaction, a catalyst was added for prepolymerization. After 4 hours, a certain amount of chain extender was added for chain extension reaction. After 2 hours, the reaction was completed and the three-necked flask was taken out to stop the test.

[0014] (3) Drying and film formation: Add a certain amount of solvent to the reaction product, stir evenly, place it in a polytetrafluoroethylene mold, let it stand at room temperature for a period of time, and then dry it in a 70°C oven for 24 hours to finally obtain a gallic acid-based polyurethane film.

[0015] Furthermore, the polyester polyol is polycaprolactone 2000 (PCL).

[0016] Furthermore, the chain extender is gallic acid (GA).

[0017] Furthermore, the diisocyanate is isophorone diisocyanate (IPDI).

[0018] Furthermore, the organic solvent is N,N-dimethylformamide (DMF).

[0019] Furthermore, the catalyst is dibutyltin dilaurate (DBTDL).

[0020] The advantages and positive effects of the present invention are:

[0021] (1) The polyurethane film prepared by the present invention has the ability to block ultraviolet rays.

[0022] (2) The polyurethane film prepared by the present invention has good tensile properties.

[0023] (3) The polyurethane film prepared by the present invention has better barrier properties.

[0024] (4) The polyurethane film forming method prepared by the present invention is simple and easy to operate and has low equipment requirements.

[0025] (5) The polyurethane film prepared by the present invention has a wide range of application scenarios and strong applicability.

[0026] (6) The polyurethane film prepared by the present invention has biodegradability. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 Flow chart for preparing polyurethane of the present invention

[0028] Figure 2 The experimental reaction mechanism diagram and the schematic diagram of the structure of each component

[0029] Figure 3 Thin film infrared test chart

[0030] Figure 4 The ultraviolet transmittance diagram in the embodiment DETAILED DESCRIPTION

[0031] The present invention will be further described in detail below with reference to the accompanying drawings and through specific embodiments. The following embodiments are merely illustrative and non-restrictive, and the scope of protection of the present invention cannot be limited thereto.

[0032] Example 1

[0033] In this embodiment, we adopt the formula in Table 1 for experimental research:

[0034] Table 1 Polyurethane film formulation

[0035]

[0036]

[0037] (1) Raw material preparation

[0038] Use a balance to accurately weigh various raw materials that have been dried and refrigerated in advance.

[0039] (2) Synthesis process

[0040] The BPU film was prepared through a two-step reaction. A 250ml round-bottom three-necked flask connected to a mechanical stirrer, a condenser, and a nitrogen inlet and outlet was used as the reaction vessel for polyurethane synthesis. The water bath temperature was raised to 80°C for preheating in advance, and nitrogen was introduced to remove the air in the round-bottom three-necked flask. A certain amount of PCL was added to the three-necked flask, and a measured amount of IPDI was added. After a period of reaction, the catalyst DBTDL was added for prepolymerization. After 4 hours, a certain amount of chain extender GA was added for chain extension reaction. The reaction was completed after 2 hours, and the three-necked flask was taken out to stop the experiment.

[0041] (3) Film formation

[0042] The synthesized product was dissolved in DMF solution, with the polyurethane content accounting for 14% of the total solution mass. The solvent and polyurethane were thoroughly mixed under magnetic stirring, and the mixed product was then poured into a polytetrafluoroethylene mold. After the film was cast and leveled, it was placed in a 70°C oven and dried for 24 hours to form a film.

[0043] (4) Performance testing

[0044] ① Mechanical properties

[0045] The tensile strength of the film was tested by preparing the specimens according to ASTM D-882. The test results are shown in Table 4.

[0046] ②Oxygen permeability test

[0047] Prepare samples according to GB / T1038-2000 and use GDP-C permeability tester to measure the oxygen permeability of polyurethane film. The permeability coefficient Qg of the film is calculated as follows:

[0048] Qg=1.157×Rg×D Formula (1-1)

[0049] Where D is the thickness of the sample (cm); Qg is the gas permeability of the film (cm 3 / m 2 ·d·Pa); Rg is the gas permeability of the film (10 -14 cm 3 cm / (cm 2 The test results are shown in Table 5.

[0050] ③Optical performance test

[0051] The spectral transmittance of the BPU film was measured using a UV-2700 spectrometer according to GB2410-80 "Test method for light transmittance and haze of transparent plastics" to characterize its transparency. The spectral range was 200nm-800nm.

[0052] ④Water contact angle

[0053] The specimens were prepared according to the GB / T30693-2014 test standard and the water contact angle of the film was tested.

[0054] ⑤ Water vapor transmission rate test

[0055] Use a film cutting tool to cut the test sample into specific sizes. Measure the film's moisture permeability according to GB1037-1988, Plastic Film and Sheeting Water Vapor Permeability Test Method (Cup Method). Set the test temperature to 38°C and the humidity to 90% RH. The water vapor permeability coefficient (Pv) is calculated using the following formula:

[0056] Pv=1.157×10 -9×WVT×D / ΔP formula (2-4)

[0057] Where WVT is the water vapor transmission rate (g / m 2 ·24h); D is the film thickness (cm); ΔP is the water vapor pressure difference across the film (Pa).

[0058] ⑥Degradability test

[0059] Cut the sample into a 20×20 cm square film, weigh its mass as m1, bury it in the soil for 1 month, dig it out, and weigh it to get the mass m2.

[0060] Example 2

[0061] In this embodiment, we adopt the formula in Table 2 for experimental research:

[0062] Table 2 Polyurethane film formulation

[0063]

[0064] (1) Raw material preparation

[0065] Use a balance to accurately weigh various raw materials that have been dried and refrigerated in advance.

[0066] (2) Synthesis process

[0067] The BPU film was prepared through a two-step reaction. A 250ml round-bottom three-necked flask connected to a mechanical stirrer, a condenser, and a nitrogen inlet and outlet was used as the reaction vessel for polyurethane synthesis. The water bath temperature was raised to 80°C for preheating in advance, and nitrogen was introduced to remove the air in the round-bottom three-necked flask. A certain amount of PCL was added to the three-necked flask, and a measured amount of IPDI was added. After a period of reaction, the catalyst DBTDL was added for prepolymerization. After 4 hours, a certain amount of chain extender GA was added for chain extension reaction. The reaction was completed after 2 hours, and the three-necked flask was taken out to stop the experiment.

[0068] (3) Film formation

[0069] The synthesized product was dissolved in DMF solution, with the polyurethane content accounting for 14% of the total solution mass. The solvent and polyurethane were thoroughly mixed under magnetic stirring, and the mixed product was then poured into a polytetrafluoroethylene mold. After the film was cast and leveled, it was placed in a 70°C oven and dried for 24 hours to form a film.

[0070] (4) Performance testing

[0071] ① Mechanical properties

[0072] The tensile strength of the film was tested by preparing the specimens according to ASTM D-882. The test results are shown in Table 4.

[0073] ②Oxygen permeability test

[0074] Prepare samples according to GB / T1038-2000 and use GDP-C permeability tester to measure the oxygen permeability of polyurethane film. The permeability coefficient Qg of the film is calculated as follows:

[0075] Qg=1.157×Rg×D Formula (1-1)

[0076] Where D is the thickness of the sample (cm); Qg is the gas permeability of the film (cm 3 / m 2 ·d·Pa); Rg is the gas permeability of the film (10 -14 cm 3 cm / (cm 2 The test results are shown in Table 5.

[0077] ③Optical performance test

[0078] The spectral transmittance of the BPU film was measured using a UV-2700 spectrometer according to GB2410-80 "Test method for light transmittance and haze of transparent plastics" to characterize its transparency. The spectral range was 200nm-800nm.

[0079] ④Water contact angle

[0080] The specimens were prepared according to the GB / T30693-2014 test standard and the water contact angle of the film was tested.

[0081] ⑤ Water vapor transmission rate test

[0082] Use a film cutting tool to cut the test sample into specific sizes. Measure the film's moisture permeability according to GB1037-1988, Plastic Film and Sheeting Water Vapor Permeability Test Method (Cup Method). Set the test temperature to 38°C and the humidity to 90% RH. The water vapor permeability coefficient (Pv) is calculated using the following formula:

[0083] Pv=1.157×10 -9 ×WVT×D / ΔP formula (2-4)

[0084] Where WVT is the water vapor transmission rate (g / m 2 ·24h); D is the film thickness (cm); ΔP is the water vapor pressure difference across the film (Pa).

[0085] ⑥Degradability test

[0086] Cut the sample into a 20×20 cm square film, weigh its mass as m1, bury it in the soil for 1 month, dig it out, and weigh it to get the mass m2.

[0087] Example 3

[0088] In this embodiment, we adopt the formula in Table 3 for experimental research:

[0089] Table 3 Polyurethane film formulation

[0090]

[0091] (1) Raw material preparation

[0092] Use a balance to accurately weigh various raw materials that have been dried and refrigerated in advance.

[0093] (2) Synthesis process

[0094] The BPU film was prepared through a two-step reaction. A 250ml round-bottom three-necked flask connected to a mechanical stirrer, a condenser, and a nitrogen inlet and outlet was used as the reaction vessel for polyurethane synthesis. The water bath temperature was raised to 80°C for preheating in advance, and nitrogen was introduced to remove the air in the round-bottom three-necked flask. A certain amount of PCL was added to the three-necked flask, and a measured amount of IPDI was added. After a period of reaction, the catalyst DBTDL was added for prepolymerization. After 4 hours, a certain amount of chain extender GA was added for chain extension reaction. The reaction was completed after 2 hours, and the three-necked flask was taken out to stop the experiment.

[0095] (3) Film formation

[0096] The synthesized product was dissolved in DMF solution, with the polyurethane content accounting for 14% of the total solution mass. The solvent and polyurethane were thoroughly mixed under magnetic stirring, and the mixed product was then poured into a polytetrafluoroethylene mold. After the film was cast and leveled, it was placed in a 70°C oven and dried for 24 hours to form a film.

[0097] (4) Performance testing

[0098] ① Mechanical properties

[0099] The tensile strength of the film was tested by preparing the specimens according to ASTM D-882. The test results are shown in Table 4.

[0100] ②Oxygen permeability test

[0101] Prepare samples according to GB / T1038-2000 and use GDP-C permeability tester to measure the oxygen permeability of polyurethane film. The permeability coefficient Qg of the film is calculated as follows:

[0102] Qg=1.157×Rg×D Formula (1-1)

[0103] Where D is the thickness of the sample (cm); Qg is the gas permeability of the film (cm 3 / m 2 ·d·Pa); Rg is the gas permeability of the film (10 -14 cm 3 cm / (cm 2 The test results are shown in Table 5.

[0104] ③Optical performance test

[0105] The spectral transmittance of the BPU film was measured using a UV-2700 spectrometer according to GB2410-80 "Test method for light transmittance and haze of transparent plastics" to characterize its transparency. The spectral range was 200nm-800nm.

[0106] ④Water contact angle

[0107] The specimens were prepared according to the GB / T30693-2014 test standard and the water contact angle of the film was tested.

[0108] ⑤ Water vapor transmission rate test

[0109] Use a film cutting tool to cut the test sample into specific sizes. Measure the film's moisture permeability according to GB1037-1988, Plastic Film and Sheeting Water Vapor Permeability Test Method (Cup Method). Set the test temperature to 38°C and the humidity to 90% RH. The water vapor permeability coefficient (Pv) is calculated using the following formula:

[0110] Pv=1.157×10 -9 ×WVT×D / ΔP formula (2-4)

[0111] Where WVT is the water vapor transmission rate (g / m 2 ·24h); D is the film thickness (cm); ΔP is the water vapor pressure difference across the film (Pa).

[0112] ⑥Degradability test

[0113] Cut the sample into a 20×20 cm square film, weigh its mass as m1, bury it in the soil for 1 month, dig it out, and weigh it to get the mass m2.

[0114] Example 4

[0115] In this embodiment, we adopt the formula in Table 4 for experimental study:

[0116] Table 3 Polyurethane film formulation

[0117]

[0118] (1) Raw material preparation

[0119] Use a balance to accurately weigh various raw materials that have been dried and refrigerated in advance.

[0120] (2) Synthesis process

[0121] The BPU film was prepared through a two-step reaction. A 250ml round-bottom three-necked flask connected to a mechanical stirrer, a condenser, and a nitrogen inlet and outlet was used as the reaction vessel for polyurethane synthesis. The water bath temperature was raised to 80°C for preheating, and nitrogen was introduced to remove the air in the round-bottom three-necked flask. A certain amount of PCL was added to the three-necked flask, and a measured amount of IPDI was added. After a period of reaction, the catalyst DBTDL was added for prepolymerization. After 4 hours, a certain amount of chain extender BDO was added for chain extension reaction. The reaction was completed after 2 hours, and the three-necked flask was removed to stop the experiment.

[0122] (3) Film formation

[0123] The synthesized product was dissolved in DMF solution, with the polyurethane content accounting for 14% of the total solution mass. The solvent and polyurethane were thoroughly mixed under magnetic stirring, and the mixed product was then poured into a polytetrafluoroethylene mold. After the film was cast and leveled, it was placed in a 70°C oven and dried for 24 hours to form a film.

[0124] (4) Performance testing

[0125] ① Mechanical properties

[0126] The tensile strength of the film was tested by preparing the specimens according to ASTM D-882. The test results are shown in Table 4.

[0127] ②Oxygen permeability test

[0128] Prepare samples according to GB / T1038-2000 and use GDP-C permeability tester to measure the oxygen permeability of polyurethane film. The permeability coefficient Qg of the film is calculated as follows:

[0129] Qg=1.157×Rg×D Formula (1-1)

[0130] Where D is the thickness of the sample (cm); Qg is the gas permeability of the film (cm 3 / m 2 ·d·Pa); Rg is the gas permeability of the film (10 -14 cm 3 cm / (cm 2 The test results are shown in Table 5.

[0131] ③Optical performance test

[0132] The spectral transmittance of the BPU film was measured using a UV-2700 spectrometer according to GB2410-80 "Test method for light transmittance and haze of transparent plastics" to characterize its transparency. The spectral range was 200nm-800nm.

[0133] ④Water contact angle

[0134] The specimens were prepared according to the GB / T30693-2014 test standard and the water contact angle of the film was tested.

[0135] ⑤ Water vapor transmission rate test

[0136] Use a film cutting tool to cut the test sample into specific sizes. Measure the film's moisture permeability according to GB1037-1988, Plastic Film and Sheeting Water Vapor Permeability Test Method (Cup Method). Set the test temperature to 38°C and the humidity to 90% RH. The water vapor permeability coefficient (Pv) is calculated using the following formula:

[0137] Pv=1.157×10 -9 ×WVT×D / ΔP formula (2-4)

[0138] Where WVT is the water vapor transmission rate (g / m 2 ·24h); D is the film thickness (cm); ΔP is the water vapor pressure difference across the film (Pa).

[0139] ⑥Degradability test

[0140] Cut the sample into a 20×20 cm square film, weigh its mass as m1, bury it in the soil for 1 month, dig it out, and weigh it to get the mass m2.

[0141] The test results are shown in Table 4.

[0142] Table 4 Test results of finished products obtained in Examples 1 to 4

[0143]

[0144] The above description is only a preferred embodiment of the present invention. It should be pointed out that a person skilled in the art can make several modifications and improvements without departing from the inventive concept, and these all fall within the scope of protection of the present invention.

Claims

1. A gallic acid-based polyurethane film comprising the following components, expressed in mass percentage: Polyester polyol 9.46~10.33%, Diisocyanate 3.39% to 4.11%, Chain extender 0.28%~0.42%, Catalyst 0.005%, Organic solvent 85.5%.

2. A polyurethane film according to claim 1, characterized in that: The diisocyanate is isophorone diisocyanate (IPDI).

3. A polyurethane film according to claim 1, characterized in that: The polyester is polycaprolactone diol 2000 (PCL2000).

4. The polyurethane film according to claim 1, characterized in that: The chain extender is gallic acid (GA).

5. The polyurethane film according to claim 1, characterized in that: The catalyst is dibutyltin dilaurate (DBTDL).

6. The polyurethane film according to claim 1, characterized in that: The organic solvent is N,N-dimethylformamide (DMF).

7. The polyurethane film according to claim 1, characterized in that: The reaction process must be carried out under a nitrogen environment.

8. A method for preparing a biodegradable polyurethane film, characterized in that: The method is: Step 1: Place the raw materials and instruments required for the reaction in a vacuum oven at 80°C the night before the reaction; refrigerate the diisocyanate in a refrigerator for 24 hours at 0°C; Step 2: Before the experiment begins, nitrogen is introduced into the connected reaction apparatus to remove air from the equipment, and the three-necked flask is heated to 80°C in a water bath. Step 3: Add polyester polyol into a three-necked flask and adjust the stirring rod speed to 100r / min. After the temperature rises to the appropriate temperature, add isocyanate dropwise, followed by a certain amount of catalyst; Step 4: Use a blender to stir continuously for about 4 hours; Step 5: Dissolve gallic acid in a certain amount of solvent and add it dropwise into the three-necked flask; Step 6: Keep the temperature and speed constant and react for another 2 hours; Step 7: Add a certain amount of solvent to the reaction product, stir evenly, place it in a polytetrafluoroethylene mold, let it stand at room temperature for a period of time, and then dry it in a 70°C oven for 24 hours to finally obtain a gallic acid-based polyurethane film.

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