High-temperature-resistant geothermal film and preparation method thereof

Abstract

The invention relates to the technical field of PET geothermal films, and discloses a high-temperature-resistant geothermal film and a preparation method thereof.The high-temperature-resistant geothermal film is obtained through blending extrusion and blow molding of polyethylene glycol terephthalate, carboxyl polyetherimide and modified graphene. The carboxyl polyetherimide contains a benzoate structural unit similar to PET, the carboxyl polyetherimide and the benzoate structural unit form an alloy-like system with good compatibility, the modified graphene is good in dispersity and excellent in compatibility with PET, meanwhile, the modified graphene contains more carboxyl groups, and the carboxyl groups and carboxyl groups of side chains of the carboxyl polyetherimide interact with each other to form hydrogen bonds and the like; the graphene can be uniformly dispersed in a composite system of PET and carboxyl polyetherimide, so that a better reinforcing effect is achieved, and the tensile strength and the elongation at break of the PET composite geothermal film are remarkably improved. After high-temperature thermal aging, the geothermal film is high in retention rate of tensile strength and elongation at break and good in high-temperature resistance.

Description

Technical Field

[0001] The present invention relates to the technical field of PET geothermal films, and specifically relates to a high-temperature resistant geothermal film and a preparation method thereof. Background Art

[0002] Geothermal films are widely used in floor heating for heating. The main materials are polyester materials such as polyethylene terephthalate. With the wide application of geothermal films, higher requirements are also put forward for their mechanical strength, toughness, high temperature resistance, waterproof and tensile resistance and other properties. Polyethylene terephthalate can be compounded with materials such as nylon, polyethylene, polyimide, and polycarbonate to obtain alloy materials with excellent properties. Polyetherimide has higher toughness, high mechanical strength, and good high temperature resistance, and is widely used.

[0003] As a high-performance nanomaterial, graphene has important applications in polymer materials such as plastics and fibers. The surface modification of graphene, improving its dispersibility, and enhancing the interfacial compatibility with the substrate have become research hotspots. Patent CN116814174B discloses a composite PET protective film and a preparation method thereof. Using polyethylene terephthalate, polyimide resin, epoxy acrylate, nano-aluminum trioxide, graphene, molecular sieve, compatibilizer, etc. as raw materials, the obtained PET main layer and PET protective film material have advantages such as high flexibility and high adhesion. However, this patent does not improve the tensile and high temperature resistance and other properties of the PET film, which is not conducive to its practical application in geothermal films and other aspects. Summary of the Invention

[0004] (1) Technical problems to be solved: The present invention provides a PET geothermal film with high thermal conductivity, high temperature resistance and excellent mechanical properties.

[0005] (2) Technical solutions: A high-temperature resistant geothermal film includes 100 parts by weight of polyethylene terephthalate, 10 - 25 parts by weight of carboxyl polyetherimide, and 0.5 - 3 parts by weight of modified graphene.

[0006] Preferably, the preparation method of the high-temperature resistant geothermal film is: adding polyethylene terephthalate, carboxyl polyetherimide, and modified graphene into a mixer for mixing, then extruding in a twin-screw extruder at a temperature of 270 - 300 °C and a screw speed of 100 - 150 r / min; pelletizing and blow molding in a blown film machine to obtain the high-temperature resistant geothermal film.

[0007] Preferably, the present invention may further include low-density polyethylene and a toughening agent ethylene-methyl acrylate-glycidyl methacrylate blend.

[0008] Preferably, the preparation method of carboxyl polyetherimide is:

[0009] Add pyridine, 2,2-bis(hydroxymethyl)propionic acid, and trimellitic anhydride acyl chloride with a molar ratio of (2.2 - 2.6):1:(2 - 2.2) to tetrahydrofuran at 0 - 5 °C. After stirring, react at 20 - 25 °C for 8 - 12 h. Then perform vacuum distillation, and recrystallize the product from dichloromethane to obtain propionate di(hydroxymethyl trimellitate).

[0010] The reaction formula is:

[0011]

[0012] Add dianhydride monomer, propionate di(hydroxymethyl trimellitate), and 4,4'-diaminodiphenyl ether with a molar ratio of (50 - 80):(20 - 50):100 to N,N-dimethylformamide. React at 20 - 30 °C for 12 - 18 h. Pour the solution onto the surface of a glass mold, and perform heat treatment in an oven at 100 - 280 °C for 7 - 8 h. Cool, shear and crush to obtain carboxyl polyetherimide. The reaction formula is:

[0013]

[0014] Preferably, the dianhydride monomer is pyromellitic dianhydride or 4,4'-biphenylether dianhydride.

[0015] The preparation method of modified graphene is as follows: Add graphene oxide to N,N-dimethylformamide, and perform ultrasonic dispersion. Then add phthalic anhydride, and the mass ratio of the two is 1:(12 - 20). Heat to 80 - 90 °C and react for 3 - 5 h. Filter, wash with ethanol, and dry to obtain modified graphene. The reaction formula is:

[0016]

[0017] (III) Technical effects: In the present invention, polyethylene terephthalate, carboxyl polyetherimide, and modified graphene are melt-blended and extruded, and then blow-molded to obtain a high-temperature resistant geothermal film. The carboxyl polyetherimide contains a benzoate structural unit similar to PET, significantly improving the polarity and interfacial compatibility between the two, forming a well-compatible alloy-like system, which is beneficial to improving the tensile properties of the PET composite geothermal film.

[0018] In the present invention, the dispersibility of the modified graphene is improved, and its compatibility with PET is excellent. At the same time, the modified graphene contains more carboxyl groups, forming hydrogen bonds and other interactions with the carboxyl groups on the side chains of the carboxyl polyetherimide, so that the graphene and the carboxyl polyetherimide also have good interfacial bonding force, enabling the graphene to be evenly dispersed in the composite system of PET and carboxyl polyetherimide, playing a better reinforcing role, and significantly improving the tensile strength and elongation at break of the PET composite geothermal film.

[0019] The PET composite geothermal film of the present invention has undergone high-temperature thermal aging, with high retention rates of tensile strength and elongation at break, showing better high-temperature resistance performance. Detailed implementation manners

[0020] The following combines specific embodiments to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0021] Example 1

[0022] (1) Add 11 mmol of pyridine, 5 mmol of 2,2-bis(hydroxymethyl)propionic acid, and 11 mmol of trimellitic anhydride acyl chloride to 20 mL of tetrahydrofuran at 5°C. After stirring, react at 20°C for 12 h, perform vacuum distillation, and recrystallize the product from dichloromethane to obtain propionate bis(hydroxymethyl trimellitate).

[0023] (2) Add 8 mmol of 4,4'-oxydianhydride, 2 mmol of propionate bis(hydroxymethyl trimellitate), and 10 mmol of 4,4'-diaminodiphenyl ether to 20 mL of N,N-dimethylformamide. React at 25°C for 18 h. Pour the solution onto the surface of a glass mold. In an oven, perform heat treatment by keeping warm at 100°C for 1 h, 160°C for 2 h, 220°C for 1.5 h, 250°C for 1.5 h, and 280°C for 1 h in sequence. Cool, shear and crush to obtain carboxyl polyetherimide.

[0024] (3) Add 0.5 g of graphene oxide to 120 mL of N,N-dimethylformamide, perform ultrasonic dispersion, then add 6 g of phthalic anhydride, heat to 90°C, react for 3 h, filter, wash with ethanol, and dry to obtain modified graphene.

[0025] (4) Add 1 kg of polyethylene terephthalate, 100 g of carboxyl polyetherimide, and 5 g of modified graphene to a mixer for mixing, and then extrude in a twin-screw extruder. The temperatures of the 1st - 4th sections are 270°C, 290°C, 300°C, and 295°C, and the screw speed is 150 r / min; pelletize, and perform blow molding in a blown film machine with a blow-up ratio of 3.0 and a stretching and traction rate of 6 m / min to obtain a high-temperature resistant geothermal film.

[0026] Example 2

[0027] (1) Add 13 mmol of pyridine, 5 mmol of 2,2-bis(hydroxymethyl)propionic acid, and 10 mmol of trimellitic anhydride chloride to 20 mL of tetrahydrofuran at 0 °C. After stirring, react at 25 °C for 8 h. Distill under reduced pressure, and recrystallize the product from dichloromethane to obtain propionate bis(hydroxymethyl trimellitate).

[0028] (2) Add 6.5 mmol of 4,4'-oxydiphthalic dianhydride, 3.5 mmol of propionate bis(hydroxymethyl trimellitate), and 10 mmol of 4,4'-oxydianiline to 25 mL of N,N-dimethylformamide. React at 30 °C for 12 h. Pour the solution onto the surface of a glass mold. In an oven, perform heat treatment by maintaining at 100 °C for 1 h, 150 °C for 2 h, 200 °C for 2 h, 240 °C for 2 h, and 280 °C for 1 h in sequence. Cool, cut into pieces and crush to obtain carboxyl polyetherimide.

[0029] (3) Add 0.5 g of graphene oxide to 150 mL of N,N-dimethylformamide, disperse ultrasonically, then add 8 g of phthalic anhydride, heat to 80 °C, react for 4 h, filter, wash with ethanol, and dry to obtain modified graphene.

[0030] (4) Add 1 kg of polyethylene terephthalate, 180 g of carboxyl polyetherimide, and 17 g of modified graphene to a mixer and mix. Then extrude in a twin-screw extruder. The temperatures of the 1st - 4th sections are 270 °C, 290 °C, 300 °C, and 295 °C, and the screw speed is 100 r / min; pelletize, and blow-mold in a blown film machine with a blow-up ratio of 3.0 and a draw rate of 6 m / min to obtain a high-temperature resistant geothermal film.

[0031] Example 3

[0032] (1) Add 5 mmol of pyromellitic dianhydride, 5 mmol of propionate bis(hydroxymethyl trimellitate) (prepared according to the method of Example 1), and 10 mmol of 4,4'-oxydianiline to 20 mL of N,N-dimethylformamide. React at 20 °C for 18 h. Pour the solution onto the surface of a glass mold. In an oven, perform heat treatment by maintaining at 100 °C for 1 h, 150 °C for 2 h, 200 °C for 2 h, 240 °C for 2 h, and 280 °C for 1 h in sequence. Cool, cut into pieces and crush to obtain carboxyl polyetherimide.

[0033] (2) Add 0.5 g of graphene oxide to 150 mL of N,N-dimethylformamide, disperse ultrasonically, then add 10 g of phthalic anhydride, heat to 80 °C, react for 5 h, filter, wash with ethanol, and dry to obtain modified graphene.

[0034] (3) Add 1 kg of polyethylene terephthalate, 250 g of carboxyl polyetherimide, and 30 g of modified graphene into a mixer for mixing, and then extrude in a twin-screw extruder. The temperatures of the 1st - 4th sections are 270 °C, 290 °C, 300 °C, and 295 °C, and the screw rotation speed is 150 r / min; pelletize, and perform blow molding in a blown film machine. The blow-up ratio is 3.0, and the stretching and traction rate is 6 m / min to obtain a high-temperature resistant geothermal film.

[0035] Comparative Example 1

[0036] (1) Extrude 1 kg of polyethylene terephthalate in a twin-screw extruder. The temperatures of the 1st - 4th sections are 270 °C, 290 °C, 300 °C, and 295 °C, and the screw rotation speed is 150 r / min; pelletize, and perform blow molding in a blown film machine. The blow-up ratio is 3.0, and the stretching and traction rate is 6 m / min to obtain a high-temperature resistant geothermal film.

[0037] Comparative Example 2

[0038] (1) Add 1 kg of polyethylene terephthalate and 100 g of carboxyl polyetherimide (prepared according to the method of Example 1) into a mixer for mixing, and then extrude in a twin-screw extruder. The temperatures of the 1st - 4th sections are 270 °C, 290 °C, 300 °C, and 295 °C, and the screw rotation speed is 150 r / min; pelletize, and perform blow molding in a blown film machine. The blow-up ratio is 3.0, and the stretching and traction rate is 6 m / min to obtain a high-temperature resistant geothermal film.

[0039] Comparative Example 3

[0040] (1) Add 1 kg of polyethylene terephthalate and 5 g of modified graphene (prepared according to the method of Example 1) into a mixer for mixing, and then extrude in a twin-screw extruder. The temperatures of the 1st - 4th sections are 270 °C, 290 °C, 300 °C, and 295 °C, and the screw rotation speed is 150 r / min; pelletize, and perform blow molding in a blown film machine. The blow-up ratio is 3.0, and the stretching and traction rate is 6 m / min to obtain a high-temperature resistant geothermal film.

[0041] Comparative Example 4

[0042] (1) Add 1 kg of polyethylene terephthalate, 100 g of carboxyl polyetherimide (prepared according to the method of Example 1), and 5 g of graphene oxide into a mixer for mixing, and then extrude in a twin-screw extruder. The temperatures of the 1st - 4th sections are 270 °C, 290 °C, 300 °C, and 295 °C, and the screw rotation speed is 150 r / min; pelletize, and perform blow molding in a blown film machine. The blow-up ratio is 3.0, and the stretching and traction rate is 6 m / min to obtain a high-temperature resistant geothermal film.

[0043] Comparative Example 5

[0044] (1) Add 10 mmol of 4,4'-biphenyl ether dianhydride and 10 mmol of 4,4'-diaminodiphenyl ether to 20 mL of N,N-dimethylformamide, react at 25 °C for 18 h, pour the solution onto the surface of a glass mold, and in an oven, perform heat treatment by keeping warm at 100 °C for 1 h, 160 °C for 2 h, 220 °C for 1.5 h, 250 °C for 1.5 h, and 280 °C for 1 h in sequence, then cool and cut into pieces and pulverize to obtain polyetherimide.

[0045] (2) Add 1 kg of polyethylene terephthalate, 100 g of polyetherimide, and 5 g of modified graphene (prepared according to the method of Example 1) into a mixer for mixing, then extrude in a twin-screw extruder, the temperatures of the 1st - 4th sections are 270 °C, 290 °C, 300 °C, and 295 °C, and the screw rotation speed is 150 r / min; pelletize, and perform blow molding in a blown film machine, the blow-up ratio is 3.0, and the stretching and traction rate is 6 m / min to obtain a high-temperature resistant geothermal film.

[0046] Comparative Example 6

[0047] (1) Add 8 mmol of 4,4'-biphenyl ether dianhydride, 2 mmol of ethylene glycol bis(trimellitic anhydride) (structural formula CAS Registry Number 1732 - 96 - 3), and 10 mmol of 4,4'-diaminodiphenyl ether to 20 mL of N,N-dimethylformamide, react at 25 °C for 18 h, pour the solution onto the surface of a glass mold, and in an oven, perform heat treatment by keeping warm at 100 °C for 1 h, 160 °C for 2 h, 220 °C for 1.5 h, 250 °C for 1.5 h, and 280 °C for 1 h in sequence, then cool and cut into pieces and pulverize to obtain polyetherimide.

[0048] (2) Add 1 kg of polyethylene terephthalate, 100 g of polyetherimide, and 5 g of modified graphene (prepared according to the method of Example 1) into a mixer for mixing, then extrude in a twin-screw extruder, the temperatures of the 1st - 4th sections are 270 °C, 290 °C, 300 °C, and 295 °C, and the screw rotation speed is 150 r / min; pelletize, and perform blow molding in a blown film machine, the blow-up ratio is 3.0, and the stretching and traction rate is 6 m / min to obtain a high-temperature resistant geothermal film.

[0049] Test the tensile properties of the geothermal film according to the method of GB / T 1040.3 - 2006. Place the geothermal film in a forced-air dryer, perform heat aging at 90 °C for 72 h, cool at room temperature for 12 h, and then test the tensile properties again.

[0050] Table 1 Tensile Strength Test

[0051]

[0052]

[0053] Table 2 Tensile Elongation at Break Test

[0054]

[0055] After testing, the high-temperature resistant geothermal films of Examples 1-3 have higher tensile strength and elongation at break. The main reason is that carboxyl polyetherimide and modified graphene are added to polyethylene terephthalate (PET). The carboxyl polyetherimide contains a benzoate structural unit similar to that of PET, significantly improving the polarity and interfacial compatibility between the two, forming a pseudo-alloy system with good compatibility, which is beneficial to improving the tensile properties of the PET composite geothermal film. At the same time, the dispersibility of the modified graphene becomes better, and its compatibility with PET is excellent. At the same time, the modified graphene contains a large number of carboxyl groups, forming hydrogen bonds and other interactions with the carboxyl groups on the side chain of the carboxyl polyetherimide, so that the graphene and the carboxyl polyetherimide also have good interfacial bonding force, enabling the graphene to be evenly dispersed in the composite system of PET and carboxyl polyetherimide, playing a better reinforcing role, and significantly improving the tensile strength and elongation at break of the PET composite geothermal film. And after high-temperature thermal aging, the retention rates of the tensile strength and elongation at break of the geothermal film are high, showing better high-temperature resistance.

[0056] In Comparative Example 1, carboxyl polyetherimide and modified graphene were not added, and the geothermal film had low tensile properties. After high-temperature thermal aging, the decline in tensile strength and elongation at break was large, the retention rate was low, and the high-temperature resistance was poor.

[0057] Compared with Example 1, in Comparative Example 2, modified graphene was not added, and in Comparative Example 3, carboxyl polyetherimide was not added, resulting in lower tensile strength and elongation at break of the PET geothermal film.

[0058] In Comparative Example 4, unmodified graphene oxide was added, which was prone to agglomeration, had poor compatibility with PET, and had a small surface carboxyl content, resulting in a lower hydrogen bond interaction force with the carboxyl groups on the side chain of the carboxyl polyetherimide. As a result, the dispersibility of graphene oxide in the composite system of PET and carboxyl polyetherimide was lower than that of Example 1, and the reinforcing effect of graphene was poor, and the tensile strength and elongation at break of the geothermal film were lower than those of Example 1.

[0059] In Comparative Example 5, propionate bis(trimellitic anhydride hydroxymethyl ester) was not added, and the prepared polyetherimide did not contain a benzoate structural unit or a carboxyl group, had poor polarity and interfacial compatibility with PET, and had a low interfacial bonding force with the modified graphene, resulting in lower tensile strength and elongation at break of the PET composite film.

[0060] In Comparative Example 6, ethylene glycol bis(trimellitic anhydride) was added, and the prepared polyetherimide contained a benzoate structural unit similar to that of PET, significantly improving the polarity and interfacial compatibility between the two, forming a miscible alloy-like system, which was beneficial to improving the tensile properties of the PET composite geothermal film. However, it did not contain carboxyl groups, and the interfacial bonding force with modified graphene was also relatively low, resulting in the tensile strength and elongation at break of the PET composite film being lower than those of Example 1.

[0061] In addition, it should be understood that although this specification is described according to embodiments, not every embodiment only contains an independent technical solution. This narrative way of the specification is only for clarity. Those skilled in the art should regard the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A high temperature resistant geothermal film, characterized in that: The high temperature resistant geothermal film comprises 100 parts by weight of polyethylene terephthalate, 10-25 parts by weight of carboxyl polyetherimide, and 0.5-3 parts by weight of modified graphene; The preparation method of the carboxyl polyetherimide is as follows: adding dianhydride monomer, propionic di(hydroxymethyl trimellitic anhydride ester) and 4,4'-diaminodiphenyl ether to N,N-dimethylformamide, pouring the solution on the surface of a mold after reaction, performing heat treatment, cooling, shearing and crushing to obtain the carboxyl polyetherimide.

2. The high temperature resistant geothermal film according to claim 1, characterized in that: The reaction is carried out at 20-30°C for 12-18 hours; the heat treatment is carried out at 100-280°C for 7-8 hours.

3. The high temperature resistant geothermal film according to claim 1, characterized in that: The molar ratio of the dianhydride monomer, propionic bis(hydroxymethyl trimellitic anhydride ester) and 4,4-biphenyl ether dianhydride is (50-80):(20-50):

100.

4. The high temperature resistant geothermal film according to claim 1, characterized in that: The dianhydride monomer is pyromellitic anhydride or 4,4'-biphenyl ether dianhydride.

5. The high temperature resistant geothermal film according to claim 1, characterized in that: The preparation method of the propionic acid bis(hydroxymethyl trimellitic anhydride ester) is as follows: pyridine, 2,2-dihydroxymethyl propionic acid and trimellitic anhydride chloride are added to tetrahydrofuran at 0-5° C., stirred, reacted at 20-25° C. for 8-12 hours, distilled under reduced pressure, and recrystallized to obtain the propionic acid bis(hydroxymethyl trimellitic anhydride ester).

6. The high temperature resistant geothermal film according to claim 4, characterized in that: The molar ratio of pyridine, 2,2-dihydroxymethylpropionic acid and trimellitic anhydride chloride is (2.2-2.6):1:(2-2.2).

7. The high temperature resistant geothermal film according to claim 1, characterized in that: The preparation method of the modified graphene is as follows: adding graphene oxide to N,N-dimethylformamide, ultrasonically dispersing, then adding phthalic anhydride, heating to 80-90° C., reacting for 3-5 hours, filtering, washing, and drying to obtain the modified graphene.

8. The high temperature resistant geothermal film according to claim 1, characterized in that: The graphene oxide is ultrasonically dispersed, and then phthalic anhydride is added in a mass ratio of 1:(12-20).

9. A method for preparing a high temperature resistant geothermal film according to any one of claims 1 to 8, characterized in that: The preparation method comprises the following steps: adding polyethylene terephthalate, carboxyl polyetherimide and modified graphene into a mixer for mixing, and then extruding in a twin-screw extruder at a temperature of 270-300° C. and a screw speed of 100-150 r / min; pelletizing, and blow molding in a film blowing machine to obtain a high-temperature resistant geothermal film.

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