A high-pressure resistant diaphragm and preparation method thereof

Abstract

The present invention relates to the technical field of diaphragms, and particularly to a high-pressure resistant diaphragm and a preparation method thereof. The present invention relates to a high-pressure resistant diaphragm and a preparation method thereof. The raw materials for its preparation include, by mass percentage, 25-35% of isocyanate, 25-35% of polymer polyol, 1-5% of auxiliary agent, 1-5% of filler, 20-30% of solvent, and 5-10% of chain extender. The high-pressure resistant diaphragm prepared by the present invention far exceeds the pressure that market products can withstand; it has higher tensile properties and is not easily torn when the elongation rate is too large; it has excellent resilience and can return to its original state in a short time; its strength and wear resistance far exceed market products, and it has a long service life; it can be applied to the diaphragm on the filter plate, closely fit with the membrane plate to form a closed cavity, with less energy consumption and high efficiency, and has greater advantages especially in improving the filtration speed and treating high-pressure filter solid-liquid mixtures.

Description

Technical Field

[0001] The present invention relates to the technical field of diaphragms, and particularly relates to a high-pressure resistant diaphragm and a preparation method thereof. Background Art

[0002] The membrane pressure of diaphragms on the market is 0.6 - 2.5 MPa. As a thermoplastic elastomer material, TPE is often used as the diaphragm of reinforced polypropylene filter plates. For example, the patent document with the application number CN201720711583.8 uses a diaphragm made of TPE material. The problem with this material diaphragm is that its recovery is poor when the elongation rate is large, that is, when the depth of the filter cavity is much larger than the thickness of the filter cake, the diaphragm will accelerate fatigue failure.

[0003] Compared with TPE elastomers, silicone diaphragms have a larger elongation rate and resilience, but they are not wear-resistant, have limited usage scenarios, and have a very short service life. Neither TPE elastomers nor silicone diaphragms can adapt to relatively high tympanic membrane pressures. To achieve relatively high tympanic membrane pressures, higher requirements are imposed on the tensile strength, elongation rate, wear resistance, and fatigue life of the diaphragm.

[0004] Therefore, providing a high-pressure resistant diaphragm with excellent tensile strength, elongation rate, wear resistance, and fatigue life is the main technical problem to be solved currently. Summary of the Invention

[0005] To solve the above problems, in the first aspect of the present invention, a high-pressure resistant diaphragm is provided. The raw materials for its preparation, by mass percentage, include 25 - 35% of isocyanate, 25 - 35% of polymer polyol, 1 - 5% of additives, 1 - 5% of fillers, 20 - 30% of solvents, and 5 - 10% of chain extenders.

[0006] The molecular structure of the isocyanate generally contains two or more -NCO (isocyanate groups), and the isocyanate is diisocyanate and polyisocyanate.

[0007] Preferably, isocyanates with an equivalent weight below 2500 are not used as polyurethane solvents.

[0008] Preferably, the viscosity of the isocyanate is 2500 - 8000 mPa·s.

[0009] The diisocyanate is selected from at least one of toluene diisocyanate, isophorone diisocyanate, diphenylmethane diisocyanate, and dicyclohexylmethane diisocyanate.

[0010] Preferably, the toluene diisocyanate is at least one of 2,4-toluene diisocyanate and 2,6-toluene diisocyanate.

[0011] The inventor found in experiments that using different types of toluene diisocyanate would affect the reaction activity. It was found in the experiments that the activity of 2,4-toluene diisocyanate was greater than that of 2,6-toluene diisocyanate during the formation of the prepolymer reaction. However, using 2,4-toluene diisocyanate or 2,6-toluene diisocyanate alone would affect the stability of the formed prepolymer and the storage time of the prepolymer. The possible reason is that the 4th -NCO in 2,4-toluene diisocyanate is far from the 2nd -NCO and methyl group, with almost no steric hindrance, while the two -NCO groups in 2,6-toluene diisocyanate are relatively close to each other, with a greater steric hindrance effect, thus affecting the reaction activity. Therefore, using 2,4-toluene diisocyanate and 2,6-toluene diisocyanate as reactants in a certain proportion can make the prepolymer more stable and have a longer storage time.

[0012] Preferably, the diisocyanate is a mixture of 2,4-toluene diisocyanate (CAS: 584-84-9) and 2,6-toluene diisocyanate (CAS: 91-08-7).

[0013] Preferably, in the mixture of 2,4-toluene diisocyanate and 2,6-toluene diisocyanate, the mass ratio of 2,4-toluene diisocyanate to 2,6-toluene diisocyanate is (5 - 10):(1 - 5).

[0014] Preferably, in the mixture of 2,4-toluene diisocyanate and 2,6-toluene diisocyanate, the ratio of 2,4-toluene diisocyanate to 2,6-toluene diisocyanate is 8:2.

[0015] Preferably, the mixture of 2,4-toluene diisocyanate and 2,6-toluene diisocyanate is 2,4-toluene diisocyanate - 80 (CAS No.: 26471-62-5).

[0016] The polymer polyol includes polyester polyol and polyether polyol.

[0017] Preferably, the viscosity of the polymer polyol is 2500 - 8000 mPa·s.

[0018] Preferably, the polymer polyol is a polyester polyol with a number average molecular weight of 1000 - 3000.

[0019] Preferably, the polyester polyol with a number average molecular weight of 1000 - 3000 includes aliphatic polyol and aromatic polyol according to whether it contains a benzene ring.

[0020] Preferably, the aliphatic polyol contains more polar groups such as ester groups and amino groups in the molecule, with strong cohesive strength and adhesion, which will improve the strength and wear resistance of the polyurethane polymer film.

[0021] Preferably, the polyester polyol is an aliphatic polyol.

[0022] Preferably, the aliphatic polyol includes saturated aliphatic polyester polyol, unsaturated aliphatic polyester polyol and caprolactone-based polyester polyol.

[0023] Preferably, the saturated aliphatic polyol includes at least one of adipic acid-based polyester polyol, succinic acid-based polyester polyol, glutaric acid-based polyester polyol, and sebacic acid-based polyester polyol.

[0024] Preferably, the adipic acid-based polyester polyol is polyethylene adipate (CAS No.: 24938-37-2).

[0025] The inventor found in the experiment that the polyurethane polymer formed by the reaction of 2,4-toluene diisocyanate-80 and polyethylene adipate is a block polymer. Generally, it is composed of flexible long chains of polyethylene adipate to form soft segments. The good flexibility causes the film to have excellent resilience and can return to its original state in a short time. The hard segments are composed of 2,4-toluene diisocyanate-80 and diethyltoluenediamine. The large cohesive energy, large spatial volume, and large rigidity in the groups cause the film to have excellent strength and wear resistance. The hard segments and soft segments are arranged alternately to form repeating structural units. In addition to containing urethane groups, hydrogen bonds can be formed within and between polyurethane molecules. The soft segments and hard segments can form microphase regions and produce microscopic phase separation. Through the excellent properties of each internal structure, the polyurethane polymer has reasonable synergistic cross-linking effects, resulting in the film not only having excellent tensile properties but also being not easily torn when stretched too much. In particular, the film can withstand the tensile stress and bending stress of the eardrum under high pressure.

[0026] Preferably, the polyester polyol is a macromolecular alcohol compound containing an ester group in the molecular main chain and having a hydroxyl group (-OH) at the end group. The polyether polyol is a polymer or oligomer containing an ether bond (-O-) in the molecular main chain structure and having a hydroxyl group (-OH) or an amino group (-NH2) at the end group.

[0027] The inventor found that 2,4-toluene diisocyanate-80 will react with water. The reaction first generates unstable carbamic acid, which then decomposes into CO2 and amine, producing bubbles. This will have a great impact on the wear resistance of the polyurethane polymer. If 2,4-toluene diisocyanate-80 is in excess, the generated amine will react with 2,4-toluene diisocyanate-80 to form urea, and thus the polyurethane polymer material cannot be formed. Therefore, the water content in the polymer polyol must be strictly controlled, and the water content is less than 0.1%.

[0028] No bubbles are allowed in the polyurethane.

[0029] The auxiliary agent is at least one of a surfactant, a reinforcing agent, a catalyst, an antioxidant, and a colorant.

[0030] In order to further improve the tear resistance, heat resistance and anti-aging performance of the diaphragm, preferably, the reinforcing agent is at least one of silica, microsilica powder, and silica powder.

[0031] Preferably, the reinforcing agent is silica (CAS: 10279-57-9), the fineness of silica is 800-1500 mesh, and the specific surface area is 200-30 m 2 / g.

[0032] The filler is at least one of glass fiber and aramid fiber.

[0033] In order to further improve the corrosion resistance and high mechanical strength of the diaphragm, preferably, the filler is glass fiber (CAS: 65997-17-3), and the diameter of the single filament is 3-10 μm.

[0034] In order to further improve the overall performance of the diaphragm, it is necessary to optimize the ratio of silica and glass fiber. Preferably, the weight ratio of silica to glass fiber is (1-2):(2-5).

[0035] In order to better provide reaction conditions, the solvent is at least one of dimethylformamide, xylene, and gasoline.

[0036] Preferably, the solvent is dimethylformamide (CAS No.: 68-12-2).

[0037] The chain extender is at least one of polyols, alicyclic alcohols, aromatic alcohols, diamines, and alkanolamines.

[0038] Preferably, the chain extender is an alcohol or amine compound with low molecular weight and multi-functional groups.

[0039] Preferably, the alcohol compounds with low molecular weight and multi-functional groups are selected from at least one of 1,4-butanediol, 1,6-hexanediol, glycerol, trimethylolpropane, diethylene glycol, triethylene glycol, neopentyl glycol, sorbitol, and diethylaminoethanol; the amine compounds with low molecular weight and multi-functional groups are selected from at least one of ethylenediamine and diethyltoluenediamine.

[0040] Preferably, the inventors found that when diethyltoluenediamine is used as the chain extender, the wear resistance of the diaphragm prepared by the preparation method described in the present invention is better, and the chain extender is diethyltoluenediamine (CAS No.: 68479-98-1).

[0041] The second aspect of the present invention provides a method for preparing a high-pressure resistant diaphragm, including the following steps:

[0042] S1, Prepolymerization: Place the polymer polyol and solvent in a reaction kettle, introduce nitrogen, add isocyanate, as well as additives and fillers, and stir. Keep the temperature at 90 - 95 °C and stir for 2 - 2.5 h;

[0043] S2, Chain extension: Cool the system to 50 - 60 °C, add the chain extender and react for 1 h to obtain a polyurethane polymer solution;

[0044] S3, Inclined pouring to form a film: The polyurethane polymer solution can be used to obtain a polyurethane polymer film through the inclined multi-point pouring process.

[0045] The film obtained by the preparation method described in the present invention is subjected to destructive testing and fatigue testing. The result of the destructive testing is excellent, and the result of the fatigue testing is grade 1. The eardrum film obtained by the preparation method described in the present invention has good tensile rate, wear resistance and fatigue life. The film can be used as the film of the filter plate and closely fit with the eardrum plate to form a closed cavity. High-pressure water is introduced on one side to squeeze the filter cake on the other side, reducing the moisture content of the filter cake. By adopting this dehydration method, the power consumption is less, only 1 - 10 degrees of electricity is required for each cycle, and the moisture content of the filter cake can be reduced by 10 - 25%. Compared with other deep dehydration methods, it is energy-saving and environmentally friendly; compared with traditional TPE films and silicone films, it has greater advantages in improving the filtration speed and treating high-pressure filter-compressed solid-liquid mixtures.

[0046] Beneficial effects:

[0047] 1. The film prepared by the preparation method described in the present invention can withstand the tensile stress and bending stress at 10 MPa high pressure due to its excellent mechanical properties, far exceeding the pressure that market products can withstand.

[0048] 2. The polyurethane polymer of the film prepared by the preparation method described in the present invention is a block polymer. Generally, it consists of a flexible long chain of oligomeric polyol as the soft segment, and diisocyanate and chain extender form the hard segment. The hard segment and the soft segment are arranged alternately to form a repeating structural unit; in addition to containing urethane groups, hydrogen bonds can be formed inside and between polyurethane molecules. The soft segment and the hard segment can form microphase regions and produce microscopic phase separation, resulting in higher tensile properties and not being easily torn when the tensile rate is too large.

[0049] 3. The carbon-carbon main chain polymer polyol in the material of the film prepared by the preparation method described in the present invention has good flexibility and is a flexible chain segment in the polyurethane main chain, resulting in excellent resilience and can return to its original state in a short time.

[0050] 4. The segments formed by the reaction of isocyanate and chain extender on the main chain of the material of the film prepared by the preparation method described in the present invention have relatively large cohesive energy, relatively large spatial volume and relatively large rigidity, resulting in its strength and wear resistance far exceeding market products and having a long service life.

[0051] 5. The diaphragm prepared by the preparation method of the present invention can be applied to the diaphragm on the filter plate, closely attached to the diaphragm plate to form a closed cavity, with less energy consumption and high efficiency, and has greater advantages especially in improving the filtration speed and treating high-pressure filtration shrinkage rate solid-liquid mixtures. Specific Embodiments

[0052] Example 1

[0053] A preparation method of a high-pressure resistant diaphragm, comprising the following steps:

[0054] S1, prepolymerization: Place the polymer polyol and the solvent in a reaction kettle, introduce nitrogen, add isocyanate, as well as additives and fillers, and stir. Keep the temperature at 90 - 95 °C and stir and react for 2 - 2.5 h;

[0055] S2, chain extension: Cool the system to 50 - 60 °C, add a chain extender and react for 1 h to obtain a polyurethane polymer solution;

[0056] S3, inclined pouring into film: The polyurethane polymer solution can be used to obtain a polyurethane polymer diaphragm through the inclined multi-point pouring process.

[0057] For the high-pressure resistant diaphragm prepared in Example 1, based on mass percentage, the raw materials contain 30% isocyanate, 30% polymer polyol, 2% additives, 3% fillers, 25% solvent, and 7% chain extender.

[0058] The isocyanate is a mixture of 2,4-toluene diisocyanate and 2,6-toluene diisocyanate, and the mass ratio of 2,4-toluene diisocyanate to 2,6-toluene diisocyanate is 8:2.

[0059] The mixture with a mass ratio of 2,4-toluene diisocyanate to 2,6-toluene diisocyanate of 8:2 is 2,4-toluene diisocyanate - 80, CAS No.: 26471 - 62 - 5.

[0060] The material 2,4-toluene diisocyanate - 80 is purchased from Guangzhou Haoyi New Material Technology Co., Ltd.

[0061] The polymer polyol is polyethylene adipate, CAS No.: 24938 - 37 - 2.

[0062] The polyethylene adipate is purchased from Aoke New Material Technology (Shanghai) Co., Ltd.

[0063] The additive is a reinforcing agent, and the reinforcing agent is silica, CAS: 10279 - 57 - 9. The fineness of silica is 1200 mesh, and the specific surface area is 250 m 2 / g.

[0064] The fumed silica was purchased from Jingyi New Materials Co., Ltd.

[0065] The filler is glass fiber, CAS: 65997-17-3, and the diameter of the single filament is 3 μm.

[0066] The glass fiber was purchased from Zhongshuo Glass Fiber Products Co., Ltd.

[0067] The solvent is dimethylformamide, CAS No.: 68-12-2.

[0068] The dimethylformamide was purchased from Tensheng Chemical Co., Ltd.

[0069] The chain extender is diethyltoluenediamine, CAS No.: 68479-98-1.

[0070] The diethyltoluenediamine was purchased from Jiangsu Haolong Chemical Industry Co., Ltd.

[0071] Example 2

[0072] Example 2 provides a method for preparing a high-pressure resistant diaphragm. The preparation method is the same as that of Example 1. The difference from Example 1 is as follows:

[0073] For the high-pressure resistant diaphragm prepared in Example 2, in terms of mass percentage of the preparation raw materials, the raw materials contain 25% isocyanate, 25% polymer polyol, 1% auxiliary agent, 1% filler, 20% solvent, and 5% chain extender.

[0074] The isocyanate is a mixture of 2,4-toluene diisocyanate and 2,6-toluene diisocyanate, and the mass ratio of 2,4-toluene diisocyanate to 2,6-toluene diisocyanate is 8:2.

[0075] The mixture with a mass ratio of 2,4-toluene diisocyanate to 2,6-toluene diisocyanate of 8:2 is 2,4-toluene diisocyanate-80, CAS No.: 26471-62-5.

[0076] The material 2,4-toluene diisocyanate-80 was purchased from Guangzhou Haoyi New Materials Technology Co., Ltd.

[0077] The polymer polyol is polyethylene adipate, CAS No.: 24938-37-2.

[0078] The polyethylene adipate was purchased from Aoke New Materials Technology (Shanghai) Co., Ltd.

[0079] The auxiliary agent is a reinforcing agent, and the reinforcing agent is fumed silica, CAS: 10279-57-9. The fineness of the fumed silica is 800 mesh, and the specific surface area is 200 m 2 / g.

[0080] The silica white was purchased from Jingyi New Materials Co., Ltd.

[0081] The filler is glass fiber, CAS: 65997-17-3, and the diameter of the single filament is 3 μm.

[0082] The glass fiber was purchased from Zhongshuo Glass Fiber Products Co., Ltd.

[0083] The solvent is dimethylformamide, CAS No.: 68-12-2.

[0084] The dimethylformamide was purchased from Tengen Chemical Co., Ltd.

[0085] The chain extender is diethyltoluenediamine, CAS No.: 68479-98-1.

[0086] The diethyltoluenediamine was purchased from Jiangsu Haolong Chemical Industry Co., Ltd.

[0087] Example 3

[0088] Example 3 provides a preparation method of a high-pressure resistant diaphragm. The preparation method is the same as that of Example 1, and the difference from Example 1 is as follows:

[0089] For the high-pressure resistant diaphragm prepared in Example 3, based on the mass percentage of the preparation raw materials, the raw materials include 35% isocyanate, 35% polymer polyol, 5% additive, 5% filler, 30% solvent, and 10% chain extender.

[0090] The isocyanate is a mixture of 2,4-toluene diisocyanate and 2,6-toluene diisocyanate, and the mass ratio of 2,4-toluene diisocyanate to 2,6-toluene diisocyanate is 8:2.

[0091] The mixture with a mass ratio of 2,4-toluene diisocyanate to 2,6-toluene diisocyanate of 8:2 is 2,4-toluene diisocyanate-80, CAS No.: 26471-62-5.

[0092] The material 2,4-toluene diisocyanate-80 was purchased from Guangzhou Haoyi New Materials Technology Co., Ltd.

[0093] The polymer polyol is polyethylene adipate, CAS No.: 24938-37-2.

[0094] The polyethylene adipate was purchased from Aoke New Materials Technology (Shanghai) Co., Ltd.

[0095] The additive is a reinforcing agent, and the reinforcing agent is silica white, CAS: 10279-57-9. The fineness of the silica white is 1500 mesh, and the specific surface area is 300 m2 / g.

[0096] The fumed silica was purchased from Jingyi New Materials Co., Ltd.

[0097] The filler is glass fiber, CAS: 65997-17-3, and the diameter of the single fiber is 10 μm.

[0098] The glass fiber was purchased from Zhongshuo Glass Fiber Products Co., Ltd.

[0099] The solvent is dimethylformamide, CAS No.: 68-12-2.

[0100] The dimethylformamide was purchased from Tensheng Chemical Co., Ltd.

[0101] The chain extender is diethyltoluenediamine, CAS No.: 68479-98-1.

[0102] The diethyltoluenediamine was purchased from Jiangsu Haolong Chemical Co., Ltd.

[0103] Comparative Example 1

[0104] Comparative Example 1 provides a method for preparing a high-pressure resistant diaphragm. The preparation method is the same as that of Example 1. The difference from Example 1 is that:

[0105] Comparative Example 1 provides a high-pressure resistant diaphragm, and the content of the glass fiber is 8%.

[0106] The glass fiber was purchased from Zhongshuo Glass Fiber Products Co., Ltd.

[0107] Comparative Example 2

[0108] Comparative Example 2 provides a method for preparing a high-pressure resistant diaphragm. The preparation method is the same as that of Example 1. The difference from Example 1 is that:

[0109] Comparative Example 2 provides a high-pressure resistant diaphragm, and the content of the fumed silica is 8%.

[0110] The fumed silica was purchased from Jingyi New Materials Co., Ltd.

[0111] Comparative Example 3

[0112] Comparative Example 3 provides a method for preparing a high-pressure resistant diaphragm. The preparation method is the same as that of Example 1. The difference from Example 1 is that:

[0113] Comparative Example 3 provides a high-pressure resistant diaphragm, and the water content of the polyethylene glycol adipate is 0.15%.

[0114] The polyethylene glycol adipate was purchased from Aoke New Materials Technology (Shanghai) Co., Ltd.

[0115] Comparative Example 4

[0116] Comparative Example 4 provides a method for preparing a high-pressure resistant diaphragm. The preparation method is the same as that of Example 1, and the difference from Example 1 is as follows:

[0117] Comparative Example 4 provides a high-pressure resistant diaphragm, and the isocyanate is 2,4-toluene diisocyanate.

[0118] The material 2,4-toluene diisocyanate is purchased from Guangzhou Haoyi New Material Technology Co., Ltd.

[0119] Comparative Example 5

[0120] Comparative Example 5 provides a method for preparing a high-pressure resistant diaphragm. The preparation method is the same as that of Example 1, and the difference from Example 1 is as follows:

[0121] Comparative Example 5 provides a high-pressure resistant diaphragm, and the isocyanate is 2,6-toluene diisocyanate.

[0122] The material 2,6-toluene diisocyanate is purchased from Guangzhou Haoyi New Material Technology Co., Ltd.

[0123] Comparative Example 6

[0124] Comparative Example 6 provides a method for preparing a high-pressure resistant diaphragm. The preparation method is the same as that of Example 1, and the difference from Example 1 is as follows:

[0125] Comparative Example 6 provides a high-pressure resistant diaphragm, and the mass ratio of 2,4-toluene diisocyanate to 2,6-toluene diisocyanate in the isocyanate is 5:5.

[0126] The mixture of the materials 2,4-toluene diisocyanate and 2,6-toluene diisocyanate with a mass ratio of 5:5 is purchased from Guangzhou Haoyi New Material Technology Co., Ltd.

[0127] Comparative Example 7

[0128] Comparative Example 7 provides a method for preparing a high-pressure resistant diaphragm. The preparation method is the same as that of Example 1, and the difference from Example 1 is as follows:

[0129] Comparative Example 7 provides a high-pressure resistant diaphragm, and the chain extender is glycerol.

[0130] The glycerol is purchased from Tengen Chemical Co., Ltd.

[0131] Performance test method

[0132] 1. Destructive test:

[0133] A filter chamber with a cavity depth of 100 mm was selected and there was no filter cake filling. The diaphragms obtained in Examples 1-3 and Comparative Examples 1-7 were subjected to 1500 diaphragm destructive cycle tests. After the tests, if the diaphragms were intact, they were recorded as excellent; if they were damaged within 500-1000 times, they were recorded as good; if they were damaged within 500 times, they were recorded as poor. The measured data were recorded in Table 1.

[0134] 2. Fatigue test

[0135] Test method: A filter chamber with a cavity depth of 80 mm and a filter cake thickness of 30 mm was selected. The diaphragms obtained in Examples 1-3 and Comparative Examples 1-7 were subjected to 8000 cycles of membrane fatigue test. After the tests, if the diaphragms were intact, they were recorded as Grade 1; if there were few diaphragm breakages, they were recorded as Grade 2; if the diaphragms were broken and unusable, they were recorded as Grade 3. The measured data were recorded in Table 1.

[0136] Performance test data

[0137] Table 1

[0138] Destructive test Fatigue test Example 1 Excellent Level 1 Example 2 Excellent Level 1 Example 3 Excellent Level 1 Comparative example 1 Poor Level 3 Comparative example 2 Good Level 3 Comparative example 3 Good Level 2 Comparative example 4 Good Level 2 Comparative example 5 Poor Level 2 Comparative example 6 Good Level 3 Comparative example 7 Good Level 2

Claims

1. A high-pressure resistant diaphragm, characterized in that, The raw materials for its preparation, by mass percentage, include 25-35% of isocyanate, 25-35% of polymer polyol, 1-5% of auxiliary agent, 1-5% of filler, 20-30% of solvent, and 5-10% of chain extender; The isocyanate is a mixture of 2,4-toluene diisocyanate and 2,6-toluene diisocyanate; the mass ratio of 2,4-toluene diisocyanate to 2,6-toluene diisocyanate in the mixture of 2,4-toluene diisocyanate and 2,6-toluene diisocyanate is 8:2; The number-average molecular weight of the polymer polyol is 1000-3000, and the water content of the polymer polyol is less than 0.1%; The polymer polyol is polyethylene adipate; The auxiliary agent is silica white; the filler is glass fiber; the weight ratio of the auxiliary agent to the filler is (1-2):(2-5); the solvent is at least one of dimethylformamide, xylene and gasoline; The chain extender is diethyltoluenediamine.

2. The high-pressure resistant diaphragm according to claim 1, characterized in that, The viscosity of the isocyanate is 2500-8000 mPa.s, and the viscosity of the polymer polyol is 2500-8000 mPa.s.

3. The preparation method of the high-pressure resistant diaphragm according to any one of claims 1-2, characterized in that, It includes the following steps: S1, prepolymerization: Place the polymer polyol and the solvent in a reaction kettle, introduce nitrogen, add the isocyanate, the auxiliary agent and the filler and stir, keep the temperature at 90-95°C, and stir and react for 2-2.5 h; S2, chain extension: Cool the system to 50-60°C, add the chain extender and react for 1 h to obtain a polyurethane polymer solution; S3, inclined pouring into film: The polyurethane polymer solution can be used to obtain a polyurethane polymer film through the inclined multi-point pouring process.