Preparation method of polyurethane material for coating conveying rubber roller

Abstract

The invention relates to a preparation method of a polyurethane material for a coating conveying rubber roller, and unification of high wear resistance and process stability of the material is realized through a prepolymerization reaction process of polyester polyol and liquefied MDI (Diphenyl Diisocyanate) in combination with a multi-component B material system containing MOCA (Metal Organic Clear Acid). The method has the advantages that the existing material formula design lacks special optimization for coating conveying working conditions such as high-speed friction, chemical corrosion and radiation environments, and the process parameters are extensively controlled, such as large temperature fluctuation and single dehydration mechanism. Through optimization of a prepolymerization process of polyester polyol and liquefied MDI, design of an MOCA-containing multi-component B material system, segmented temperature control, nitrogen protection and other process innovations, the defects in the prior art are systematically overcome, and the technical breakthrough that the wear resistance is improved by 3-5 times, the production efficiency is improved by 30%, and the storage life is prolonged to 6 months is achieved.

Description

Technical Field

[0001] The invention relates to the technical field of polyurethane material processing, in particular to a method for preparing a polyurethane material for a film-coated conveying rubber roller. Background Art

[0002] In the field of coated conveyor rollers, the application of traditional rubber materials (such as nitrile rubber) and some existing polyurethane materials has obvious technical bottlenecks, as follows: For the application of traditional rubber materials: Optical film conveying scenarios: Electronic material factories use nitrile rubber rollers, typically used in high-precision winding machines. They rotate at 150 m / min, have a Shore hardness of 65A, a tensile strength of 20 MPa, and an elongation at break of 450%. Due to the material's insufficient wear resistance, wear reaches 0.10 g / cm². After three to four months of use, noticeable grooves develop on the roller surface, resulting in film thickness uniformity errors exceeding 3 μm and a product yield of only 92%, necessitating frequent roller replacement.

[0003] Radiation resistance conditions: When ordinary polyurethane rubber roller materials currently sold on the market are used in semiconductor PVD equipment, the surface becomes brittle after 5 months in a fluorine-containing plasma atmosphere and a cumulative radiation dose of 20kGy / month. The coating defect rate rises to 15%. Its radiation resistance can only withstand less than 20kGy, which cannot meet the long-term stability requirements of semiconductor coating.

[0004] The existing polyurethane material process has the following defects: Low production process efficiency: In the traditional polyurethane prepolymer preparation process, polyester polyol dehydration needs to be continued at 120-130°C for 3-4 hours, and the reaction temperature control accuracy is low (±5°C), resulting in a total prepolymer synthesis cycle of up to 6-8 hours and vacuum degassing taking 40-60 minutes. The overall production efficiency is more than 30% lower than that of the present invention.

[0005] Insufficient storage stability: The existing technology does not adopt a nitrogen-protected storage system. After the prepolymer is stored in a normal temperature and humidity environment for 1-2 months, the tensile strength decreases by more than 15% and the abrasion increases by 20%, which cannot meet the material storage needs of industrial mass production.

[0006] From the above, it can be seen that the existing technology mainly has the following technical problems: 1. Material performance defects Insufficient wear resistance: Traditional rubber materials have large wear and tear and cannot meet the friction loss requirements of high-speed coating and conveying scenarios.

[0007] Poor resistance to environmental corrosion: After immersion in 5% sulfuric acid or 10% sodium hydroxide solution for 72 hours, the strength retention rate of traditional nitrile rubber is less than 80%. The radiation resistance of existing polyurethane materials cannot meet the 50kGy dose requirement of semiconductor working conditions.

[0008] Mechanical performance limitations: The elastic recovery rate of traditional materials is only about 85%. After long-term use, the rubber roller will deform significantly, resulting in a decrease in coating accuracy.

[0009] 2. Process technology bottleneck Dehydration process is time-consuming: the existing technology requires 3-4 hours to complete the dehydration of polyester polyol, and the residual moisture content is greater than 0.1%.

[0010] Lengthy production cycle: The total cycle from prepolymer synthesis to demoulding is long, taking 12-15 hours.

[0011] Short storage period: The storage period of existing materials is only 1-2 months, which cannot meet the material turnover needs in modern industrial production. Summary of the Invention

[0012] In order to solve the above technical problems, the present invention provides a method for preparing polyurethane materials for coating conveying rollers. By optimizing the formula composition and process parameters, a polyurethane elastomer with high wear resistance, excellent elasticity and environmental corrosion resistance is prepared to meet the high-precision requirements of coating conveying scenarios.

[0013] To achieve the above object, the present invention provides the following technical solutions: A method for preparing a polyurethane material for a coated conveyor rubber roller includes the synthesis of polyurethane prepolymers A and B and subsequent operation processes. The specific steps are as follows: Synthesis of polyurethane prepolymer A: S1. Raw material pretreatment Polyester polyol: In winter, the iron barrel needs to be loosened and placed in an oven for drying. The heating can be synchronized with the vulcanization of the product. In summer, it is in liquid form and can be directly added to the reactor.

[0014] Liquefied MDI: The baking temperature should be controlled at 30-50℃ to avoid raw material deterioration caused by high temperature. The baking time should be controlled when baking together with the finished product.

[0015] S2, polyester polyol dehydration Add the melted polyester polyol into the synthesis reactor, turn on the oil temperature for heating and stirring, and set the oil temperature to 120℃; when the material temperature rises to about 100℃, turn on the vacuum pump for dehydration, and vacuum at 110℃ for 1-2 hours.

[0016] If plasticizer needs to be added, the plasticizer can be heated and then mixed with the polyester for dehydration; if the moisture content of the polyester is low, the dehydration step can be replaced by increasing the amount of liquefied MDI.

[0017] S3, liquefied MDI addition Calculate the amount of liquefied MDI to be added based on the amount of polyester polyol used, control its temperature at 30-50°C, gradually add it to the reactor, control the addition time to 10-15 minutes, and continue stirring during the addition process.

[0018] S4, temperature control reaction After adding liquefied MDI, the temperature of the reactor material naturally rises to 80-90°C. When the temperature begins to drop, the heating and insulation are turned on and the temperature is set to 90°C. The reaction lasts for 2-2.5 hours, during which the material temperature is controlled not to exceed 95°C.

[0019] S5. Vacuum treatment After the reaction is completed, maintain the temperature and turn on the vacuum pump. First, evacuate the mixture while stirring for 15-30 minutes, then stop stirring and let it stand and evacuate the mixture until there are no bubbles in the prepolymer to reduce the content of free liquefied MDI.

[0020] S6. Cooling and discharging After vacuuming is completed, turn off the heating and start the circulating water, reduce the material temperature to below 70℃, discharge the material into a dry polyester barrel (capacity 175-200 kg), immediately fill it with nitrogen for protection, seal it and store it in a dry, ventilated, waterproof, moisture-proof and sun-proof workshop; if used on the same day, it can be directly transferred to the casting machine material tank for vacuum degassing.

[0021] Synthesis of polyurethane prepolymer B S1. Raw material melting After MOCA (4,4'-methylenebis(2-chloroaniline)) is heated and melted, it is added into the reactor in proportion.

[0022] S2. Adding auxiliary materials Add dimethylthiotoluenediamine, stannous octoate, triethylenediamine, diethylene glycol dibenzoate and other auxiliary materials according to the formula ratio, and control the temperature at around 110°C.

[0023] The role of dimethylthiotoluenediamine: This amine chain extender contains a thioether group, which works synergistically with MOCA to form a denser cross-linked network, making the material less likely to produce abrasive particles falling off under high-speed friction. Compared with the traditional MOCA system, the wear resistance is improved by 40%.

[0024] S3, dehydration of material B Stir the mixed raw materials thoroughly, turn on the vacuum pump to evacuate until there is no moisture, and control the mixing time to 30-40 minutes.

[0025] S4, cooling and discharging S5. After vacuuming, cool the material to below 70℃, fill it with nitrogen for protection and seal it. The storage conditions are the same as those of material A. When used on the same day, it can be transferred to the casting machine material tank for vacuum degassing.

[0026] Polyurethane prepolymer operation process S1. Storage and preheating The prepolymer should be stored in a dry and oil-free warehouse and baked below 80℃ before use, and heated to 80-85℃; the melting temperature of material B should be controlled at 120℃.

[0027] S2. Mold processing Brush the mold with release agent in advance, polish the surface of the iron core, clean and degrease it, then brush it with glue, let it dry at room temperature, and put it in the oven after assembling the mold and bake it thoroughly at 100-120℃.

[0028] S3, metering and mixing Accurately measure material B according to the corresponding proportion of the prepolymer, mix material A and material B, and then pour them. After pouring, put them back into the oven for vulcanization.

[0029] S4, demoulding and post-processing De-mould the product 35-60 minutes after pouring and closing the mould, place it at room temperature and then clean and sort it.

[0030] The method shown in this application has the following innovations: 1. Formula innovation: A specific polyester polyol and liquefied MDI are compounded as material A, and combined with a material B system containing MOCA and multi-component additives to form a special formula for coating and conveying conditions. Compared with traditional rubber materials, the wear resistance is increased by 3-5 times, and the radiation resistance is improved by 40%.

[0031] 2. Process optimization: Segmented temperature control technology: During the synthesis of material A, the dehydration temperature (110°C), reaction temperature (90°C) and vacuum time are precisely controlled to ensure the regularity of the molecular chain and reduce the bubble rate to below 0.5%.

[0032] Flexible dehydration mechanism: Dynamically adjust the dehydration process or MDI dosage according to the moisture content of polyester, simplifying the operation while ensuring the density of the material; Nitrogen protected storage: prevents prepolymer from absorbing moisture and deteriorating, extending the storage period to 6 months. Existing technology usually only allows storage for 1-2 months.

[0033] The beneficial effects of the present invention are: This method stems from a lack of specialized optimization for coating transport conditions, such as high-speed friction, chemical corrosion, and radiation environments, in existing material formulations. Furthermore, the process parameters are crudely controlled, resulting in large temperature fluctuations and a single dehydration mechanism. This method systematically addresses these shortcomings through optimized prepolymerization of polyester polyols and liquefied MDI, the design of a multi-component B material system containing MOCA, and process innovations such as staged temperature control and nitrogen protection. The result is a technological breakthrough that improves wear resistance by 3-5 times, increases production efficiency by 30%, and extends the shelf life to 6 months.

[0034] The performance has the following advantages: the prepared polyurethane material has a wide Shore hardness range (A20-D70), an elongation of 500%-1500%, a large elastic load support capacity, and a significant shock absorption effect, which meets the mechanical requirements of different coating equipment.

[0035] The process has the following advantages: through segmented temperature control and precise measurement, the process repeatability is good, and the product yield is increased to more than 98%, which is 15% higher than the existing technology; the pouring and demolding time is shortened to 35-60 minutes, and the production efficiency is increased by 30%.

[0036] It has the following advantages in application: the material has excellent oil resistance, acid resistance, alkali resistance and radiation resistance. Its service life in electronic coating production lines can reach 4-6 times that of traditional rubber rollers, reducing equipment maintenance costs by more than 50%. DETAILED DESCRIPTION Example 1

[0037] The preparation method of the polyurethane material of the coated conveying rubber roller for standard working conditions comprises the following steps: Preparation of polyurethane prepolymer A: 100 kg of polyester polyol (molecular weight 2000) was placed in an oven for drying. After adding it into the reactor, the oil temperature was turned on and heated to 120°C. When the material temperature reached 100°C, vacuum was applied for 1.5 hours for dehydration.

[0038] According to the ratio of n (polyester hydroxyl): n (MDI) = 1:2.1, weigh 55 kg of liquefied MDI, control the temperature at 40°C, add it into the reactor within 12 minutes, and stir to react.

[0039] The material temperature naturally rises to 85°C and then is kept at 90°C for reaction for 2 hours. After vacuuming for 20 minutes, the temperature is lowered to 65°C and discharged into a 175kg drying barrel, which is then filled with nitrogen and sealed.

[0040] Preparation of polyurethane prepolymer B material: Weigh 30 kg of MOCA and heat it to melt. Add it to the reactor and then add 15 kg of dimethylthiotoluenediamine, 0.5 kg of stannous octoate, 0.3 kg of triethylenediamine, and 8 kg of diethylene glycol dibenzoate. Stir at 110 ° C for 35 minutes, evacuate until there are no bubbles, then cool to 60 ° C and discharge.

[0041] Operation process: Heat material A and material B to 82℃ and 120℃ respectively, and bake the mold thoroughly at 110℃.

[0042] Mix material A and material B in a ratio of 10:3 (mass ratio), stir and pour into the mold, put into the oven at 100°C for vulcanization for 4 hours, demould after 45 minutes, and place at room temperature for 24 hours.

[0043] Performance testing: Wear resistance: Abrasion loss is 0.03g / cm² (ASTMD4060), which is 1 / 4 of traditional nitrile rubber. Tensile strength: 32MPa, elongation 650%. Acid resistance: After immersion in 5% sulfuric acid solution for 72 hours, the strength retention rate is 92%. Example 2

[0044] Based on Example 1, a method for preparing a polyurethane material for a coated conveyor roller for radiation-resistant working conditions comprises the following steps: Adjustments to polyurethane prepolymer A: Polyester polyol was replaced with fluorinated modified polyester (molecular weight 1500), and 10 kg of diethylene glycol dibenzoate was added during dehydration. The amount of liquefied MDI was increased by 5% to replace the dehydration step.

[0045] Adjustments to polyurethane prepolymer B material: the amount of dimethylthiotoluenediamine was increased to 18 kg, and 0.8 kg of radiation-resistant additive was added. The radiation-resistant additive was a compound of antimony trioxide and zinc borate.

[0046] Performance testing: The radiation dose resistance reaches 50kGy and the strength retention rate is 85%, which is suitable for semiconductor coating equipment. Example 3

[0047] Based on Example 1, the preparation method of the polyurethane material for the coated conveying rubber roller for standard working conditions can also adopt the following steps: S1. Raw material pretreatment Polyester polyol: Use polyethylene adipate with a molecular weight of 1000. In summer, it can be added directly into the reactor in liquid form. In winter, it needs to be baked in an oven at 60°C for 2 hours to ensure complete melting.

[0048] Liquefied MDI: Preheat in a 40°C thermostat for 2 hours before use. Control the temperature between 35-45°C to avoid isocyanate group failure caused by high temperature.

[0049] S2, synthetic polyurethane prepolymer A material Dehydration: Add 150 kg of polyester polyol to the reactor and heat the oil to 120°C with a stirring rate of 150 rpm. When the material temperature reaches 105°C, start the vacuum pump and maintain dehydration at 110°C under a vacuum of -0.09 MPa for 1.5 hours until the moisture content is less than 0.05%. Moisture content is determined by Karl Fischer titration. If the actual moisture content of the raw material is 0.03%, the dehydration step can be replaced by increasing the amount of liquefied MDI by 3% based on the amount of polyester polyol used to simplify the process.

[0050] Polymerization reaction: 78 kg of liquefied MDI was weighed according to the ratio of n (polyester hydroxyl) to n (MDI) = 1:2.05 and added to the reactor in three portions, with an interval of 5 minutes between each addition. The addition time was controlled within 12 minutes, and the stirring rate was increased to 200 rpm during the addition process.

[0051] After the reaction temperature naturally rises to 88°C, an oil bath is opened to maintain the temperature at 90°C and the reaction is carried out for 2 hours. During this period, the material temperature is monitored in real time by a thermocouple to ensure that it does not exceed 92°C to avoid excessive cross-linking of the molecular chains.

[0052] Vacuum treatment: After the reaction is completed, maintain the temperature at 90°C, stir and evacuate for 20 minutes until the temperature reaches 65°C (vacuum degree -0.095MPa), then stand and evacuate for 15 minutes until no bubbles overflow from the prepolymer surface and the free MDI content drops below 0.8%. The MDI content can be determined by gas chromatography. Discharge the material into a 175kg drying drum and seal it with nitrogen.

[0053] S3, synthetic polyurethane prepolymer B material: Raw material ratio: MOCA 40kg, dimethylthiotoluenediamine 20kg, stannous octoate 0.8kg, triethylenediamine 0.5kg, diethylene glycol dibenzoate 10kg.

[0054] Mixing process: melt MOCA at 130℃ and add it into the reactor, then add other auxiliary materials in turn, control the temperature at 110±5℃ and stir for 30 minutes, evacuate until there are no bubbles, then cool to 60℃ and discharge the materials, dehydrate at a vacuum degree of -0.09MPa for 40 minutes, until no hydroxyl absorption peak is detected by infrared spectrum detection.

[0055] S4, casting and vulcanization Material preheating: Material A is baked at 80℃ for 2 hours and then heated to 83℃, and Material B is heated to 120℃ to maintain fluidity.

[0056] Mold processing: The iron core is polished with 80-grit sandpaper, cleaned with acetone, and then coated with polyurethane special glue (XY-401). It is dried at room temperature for 4 hours and the mold is preheated in a 110℃ oven for 3 hours.

[0057] Vulcanization: Mix materials A and B in a mass ratio of 10:3, vacuum degas for 5 minutes and pour into the mold, vulcanize in a 100℃ oven for 3 hours, demould after 40 minutes, and place at room temperature for 72 hours to complete the post-curing. Example 4

[0058] Based on Example 3, a method for preparing a polyurethane material for acid and alkali resistant working conditions includes the following steps: S1. Formula Improvement Adjustment of polyurethane prepolymer A: polyester polyol is replaced with fluorine-modified polycarbonate diol (molecular weight 2000), and the amount of liquefied MDI is increased to n(polyester hydroxyl):n(MDI)=1:2.2 to improve hydrolysis resistance.

[0059] Addition of polyurethane prepolymer B material: Add 5% of silane coupling agent (KH-550) to the original formula to enhance the interface bonding strength.

[0060] S2. Process adjustment Dehydration temperature: The dehydration temperature of polyester polyol is increased to 115°C and the vacuuming time is extended to 2 hours to ensure that the fluoride is completely dried.

[0061] Vulcanization conditions: After pouring, vulcanize at 120℃ for 2 hours, and then vulcanize at 80℃ for 12 hours to form a dense cross-linked network.

[0062] Experimental data and performance test report 1. Mechanical properties comparison table

[0063] 2. Environmental resistance test results Acid and alkali resistance: Example 3: After immersion in 5% H2SO4 solution for 72 hours, the strength retention rate is 93%, and after immersion in 10% NaOH solution for 72 hours, the strength retention rate is 89%.

[0064] Example 4: After immersion in 5% H2SO4 solution for 72 hours, the strength retention rate was 96%; after immersion in 10% NaOH solution for 72 hours, the strength retention rate was 92%, which was significantly better than traditional materials (acid / alkali retention rate <80%).

[0065] Weather resistance: After 1000 hours of xenon lamp aging, the yellowing index ΔY of Example 3 is 3.2, and the tensile strength retention rate is 88%; the ΔY of Example 4 is 2.5, and the retention rate is 91%. The retention rate of existing materials is usually less than 80%.

[0066] Radiation resistance: After 50kGy γ-ray irradiation, Example 2 has a tensile strength retention rate of 85% and an elongation at break retention rate of 78%, which is suitable for semiconductor coating equipment. Compared with traditional rubber irradiation, the strength decreases by more than 50%.

[0067] 3. Comparison of process parameters

[0068] IV. Inspection Report 1. Testing basis Abrasion resistance: ASTM D4060 (using rotating disc method) Tensile properties: GB / T528-2019 Chemical resistance: GB / T3512-2014 (using hot air aging method) Hardness: GB / T531.1-2008 (using Shore hardness tester) 2. Conclusion The polyurethane material prepared by this method has better performance than traditional rubber and existing polyurethane rubber roller materials. Its wear resistance is improved by 3-5 times, and its acid and alkali resistance is improved by 20%-30%.

[0069] The process parameters are highly controllable, the dehydration time is shortened by 50%, the production efficiency is increased by 30%, and the yield rate reaches more than 98%, which meets the requirements of industrial-scale production.

[0070] Through the coordinated optimization of formula and process, the material maintains stable performance in the temperature range of -20°C to 80°C, meeting the wide temperature working requirements of coating conveying equipment.

[0071] 5. Application example data of different working conditions

[0072] The following tests are conducted on the polyurethane material used for coating conveyor rollers: 1. Basic test information Test product: polyurethane elastomer material obtained in Example 3 and Example 4 Test basis: GB / T528-2019 "Determination of tensile stress-strain properties of vulcanized rubber or thermoplastic rubber" GB / T531.1-2008 "Vulcanized rubber or thermoplastic rubber indentation hardness test part 1: Shore durometer method" ASTMD4060-18 "StandardTestMethodforAbrasionResistanceofOrganicCoatingsbytheTaberAbraser" GB / T3512-2014 "Hot air aging and heat resistance test for vulcanized rubber or thermoplastic rubber" GB / T1690-2010 Test method for resistance of vulcanized rubber or thermoplastic rubber to liquids Testing period: May 10, 2025 - June 15, 2025 2. Mechanical properties test 2.1 Test Purpose Verify whether the basic mechanical properties of polyurethane materials meet the requirements for the use of coated conveyor rollers, and compare the performance differences of traditional materials.

[0073] 2.2 Test samples Example 3 Sample: polyurethane material for standard working conditions, Shore hardness 75A.

[0074] Example 4 Sample: polyurethane material for acid and alkali resistant working conditions, Shore hardness 80A.

[0075] Control samples: traditional nitrile rubber (hardness 65A) and commercially available ordinary polyurethane rubber roller material (hardness 70A).

[0076] 2.3 Test Equipment Electronic universal testing machine (50kN range, accuracy ±1%) Shore hardness tester (Type A, accuracy ±1HA) Abrasion testing machine (Taber 5135 model, equipped with CS-10 wheels) 2.4 Test Results

[0077] 2.5 Data Analysis The tensile strength of Examples 3 and 4 is increased by 75%-90% compared with traditional nitrile rubber, and the elongation at break is increased by 50%-40%, indicating that the materials have stronger load capacity and deformation resistance.

[0078] Wear resistance data shows that the wear of the material of the present invention is only 1 / 4 of that of nitrile rubber and 1 / 2 of that of commercially available polyurethane, confirming its characteristics as the "king of wear resistance" and making it particularly suitable for high-speed transportation scenarios.

[0079] The elastic recovery rate exceeds 95%, which is 10%-15% higher than traditional materials. It can reduce the permanent deformation of the rubber roller after long-term use and ensure the coating accuracy.

[0080] 3. Environmental resistance test 3.1 Acid and alkali resistance test 3.1.1 Test conditions Reagents: 5% sulfuric acid solution (pH=1.3), 10% sodium hydroxide solution (pH=13) Temperature: 23±2℃ Time: 72 hours Test method: Soak the sample in the reagent and take samples regularly to detect changes in mechanical properties.

[0081] 3.1.2 Test Results

[0082] 3.2 Weather resistance test 3.2.1 Test conditions Equipment: Xenon lamp aging test chamber (wavelength 280-800nm, irradiance 550W / m²) Temperature: 65±3℃ (blackboard temperature) Humidity: 65±5%RH Cycle: 1000 hours (equivalent to 1 year of outdoor exposure) 3.2.2 Test Results

[0083] 3.3. Testing the Radiation Resistance of the Polyurethane Material Obtained in Example 2 3.3.1 Test conditions Radiation source: Cobalt-60 gamma rays Dose rate: 1 kGy / h Cumulative dose: 50 kGy Test standard: GB / T12702-2014 "Test method for static electricity on textiles" 3.3.2 Test Results Tensile strength retention rate: 85% Elongation at break retention rate: 78% Surface resistance change rate: <10% (meeting the antistatic requirements of semiconductor equipment) 4. Process performance test 4.1. Dehydration efficiency comparison

[0084] 4.2. Production cycle test

[0085] 4.3 Storage stability test Conditions: 23℃±2℃, humidity <50%RH, nitrogen protection.

[0086] Results: After 6 months of storage, the tensile strength retention rate of the sample in Example 3 was 92%, and the wear loss change was less than 5%. The performance of the traditional material decreased by more than 15% after 2 months of storage.

[0087] 5. Actual working condition application test 5.1 Optical Film Delivery Scenario Equipment: High-precision winding machine (speed 150m / min) Testing period: 12 months result: The material of the present invention has no obvious wear on the surface of the rubber roller and the error of the uniformity of the film thickness is less than 1 μm.

[0088] Traditional nitrile rubber: Grooves appear on the surface after 4 months, and the thickness error is greater than 3μm.

[0089] The cost of roller replacement was reduced by 80%, and the product yield rate increased from 92% to 99%.

[0090] 5.2 Semiconductor Coating Scenario Environment: Fluorine plasma atmosphere, cumulative radiation dose 20kGy / month

[0091] Testing period: 10 months.

[0092] result: The radiation-resistant material of Example 2: has no cracks on the surface and the coating uniformity meets the standards.

[0093] The polyurethane currently sold on the market: The surface becomes brittle after 5 months, and the coating defect rate rises to 15%.

[0094] 6. Test Conclusion Significant performance advantages: The mechanical properties of the polyurethane material prepared by the present invention are superior to those of traditional rubber and commercially available polyurethane in all aspects, the wear resistance is improved by 3-5 times, the acid and alkali resistance retention rate exceeds 90%, and the radiation resistance meets the requirements of semiconductor working conditions.

[0095] The process efficiency is outstanding: dehydration time is shortened by 50%, production cycle is reduced by 30%, storage period is extended to 6 months, and it is suitable for industrial continuous production.

[0096] Wide range of application scenarios: In high-precision scenarios such as optical thin films and semiconductor coatings, the service life is 4-6 times that of traditional materials, and equipment maintenance costs are reduced by more than 50%.

[0097] Standard compliance: All indicators comply with the requirements of relevant standards such as GB / T2941-2006 "Rubber physical test methods - General procedures for specimen preparation and adjustment", and have industrial promotion value.

[0098] The above shows and describes the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The above embodiments and descriptions are merely preferred examples of the present invention and are not intended to limit the present invention. Various changes and improvements may be made to the present invention without departing from the spirit and scope of the present invention. Such changes and improvements fall within the scope of the present invention. The scope of protection claimed in the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for preparing a polyurethane material for a coated conveyor roller, characterized in that: The following steps are involved: Preparation of polyurethane prepolymer material A: Dehydrate polyester polyol and react with liquefied MDI, control the reaction temperature at 80-90°C, react for 2-2.5 hours, and evacuate until there are no bubbles; Preparation of polyurethane prepolymer B: Mix MOCA, dimethylthiotoluenediamine, catalyst and plasticizer and dehydrate them, controlling the temperature at around 110°C; Polyurethane prepolymer A and polyurethane prepolymer B are stored under nitrogen protection in an environment with a temperature of ≤25°C and a humidity of <50% RH. When the moisture content of the polyester polyol is <0.03%, the amount of liquefied MDI is increased by 3%-5% to replace the dehydration step. Operation process: Heat polyurethane prepolymer A and polyurethane prepolymer B to 80-85℃ and 120℃ respectively, then mix and pour, and vulcanize and demould.

2. The preparation method according to claim 1, wherein: The polyester polyol dehydration step comprises heating the polyester polyol to 100-120° C. and evacuating the polyester polyol at a vacuum degree below -0.09 MPa for 1-2 hours until the moisture content is less than 0.05%; when the moisture content of the polyester polyol is less than 0.03%, the dehydration step is replaced by increasing the amount of liquefied MDI by 3%-5% of the mass of the polyester polyol.

3. The preparation method according to claim 1 or 2, characterized in that: During the reaction of the liquefied MDI and polyester polyol, the addition temperature of the liquefied MDI is controlled to be 30-50°C, the addition time is 10-15 minutes, the reaction temperature is maintained at 80-90°C, the reaction time is 2-2.5 hours, and the material temperature does not exceed 95°C.

4. The preparation method according to claim 1, wherein: The catalyst in the material B includes stannous octoate and triethylenediamine, and the plasticizer is diethylene glycol dibenzoate; The preparation steps of the material B are as follows: melt MOCA and mix it with dimethylthiotoluenediamine, a catalyst, and a plasticizer; stir it at 110±5° C. for 30 to 40 minutes; and vacuum dehydrate it until there are no bubbles.

5. The preparation method according to claim 1, wherein: The mixing ratio of material A to material B is 10:3 to 10:4 by mass. Before mixing, material A is heated to 80 to 85° C., and material B is heated to 120° C. After mixing, vacuum degassing is performed for 5 to 10 minutes before pouring.

6. The preparation method according to claim 1, wherein: In the preparation method, the mold processing steps include: polishing the surface of the iron core with 80-100 grit sandpaper and then cleaning it with acetone, applying special polyurethane glue and drying it at room temperature for more than 4 hours, and preheating the mold in a 100-120°C oven for 2-3 hours to improve the bonding strength between the rubber roller and the iron core.

7. The preparation method according to claim 1, characterized in that After the material A and the material B are mixed and poured, they are vulcanized at 100-120° C. for 2-4 hours, demoulded 35-60 minutes after the mold is closed, and then placed at room temperature for more than 24 hours to complete post-curing.

8. The preparation method according to claim 1, characterized in that The storage conditions of the prepolymers A and B are as follows: nitrogen protection, storage in a dry and ventilated environment with a temperature of ≤25°C and a humidity of <50%, and a storage period of ≥6 months.

9. The preparation method according to claim 1, wherein: The polyurethane material prepared according to the method has a Shore hardness of A20 to D70, a tensile strength of ≥32 MPa, an elongation at break of 500% to 1500%, an abrasion loss of ≤0.03 g / cm², and an elastic recovery rate of ≥95%.

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