Method, system and program product for characterizing processing property and heat generation property of polyurethane material for tire filling

Abstract

The invention relates to the technical field of tire manufacturing, in particular to a method, a system and a program product for characterizing process performance and heat generation performance of a polyurethane material for tire filling. According to the method, three-stage in-situ tests of room-temperature pouring, constant-temperature curing and high-temperature strain scanning are sequentially carried out on the same sample, and key parameters such as initial viscosity, operable time, gel points, final modulus and final loss factors are measured in real time. The method overcomes the defects of discrete test results and lack of processing window indexes after traditional curing, can comprehensively reflect the machinability and thermal safety performance of the polyurethane filler, and is suitable for raw material evaluation, formula optimization and production line process control.

Description

Technical Field

[0001] The present invention relates to the technical field of tire manufacturing, and in particular to a method, system and program product for characterizing the process performance and heat generation performance of polyurethane material for tire filling. Background Art

[0002] With the rapid adoption of aerial work platforms, port loading and unloading vehicles, and mining vehicles, solid or semi-solid polyurethane-filled tires have become an important alternative to pneumatic tires due to their advantages such as being "blow-proof" and "maintenance-free." Polyurethane elastomers can be directly poured into the tire cavity and cured into an elastic inner core, significantly improving tire safety and service life. Numerous patent documents focus on improving formulations and preparation processes: for example, Chinese invention application CN116102709A discloses a polyurethane composite suitable for solid tire core filling and its pouring-curing process, emphasizing low-pressure pouring and controlled preheating to achieve a uniform elastomer.

[0003] However, polyurethane fillers will continue to heat up during service; if the internal heat release is superimposed on the heat accumulated during tire operation, the elastomer may soften, liquefy, or even collapse as a whole, causing the aerial work vehicle to become unstable (see Figure 1 The industry typically monitors tire temperature using whole-tire bench or road tests (see the SAE white paper "Thermal Properties and Filling Pressures"). However, this method is costly, time-consuming, and significantly affected by the test scenario, making it difficult to use for raw material screening and rapid process window optimization.

[0004] To evaluate the thermal safety of materials, existing technologies often perform heat resistance or thermomechanical testing after complete curing. For example, Chinese invention patent application CN118311083A provides a polyurethane material heat resistance testing device that measures the thermal failure temperature of an elastomer using external heating. Chinese invention patent CN112341978B introduces modifiers and chain extenders into the polyurethane hot melt adhesive system to improve the thermal stability of the finished adhesive in both high and low temperature environments. Chinese invention patent CN1373147A discloses a TPU production process that continuously controls melt viscosity to achieve a consistently thermally stable elastomer. Common drawbacks of these methods include: 1. They deviate from the in-situ reaction process: testing is performed only after curing is complete, ignoring the impact of differences in the reaction rates of components A and B on final performance and heat generation; 2. They lack process window parameters: they cannot provide indicators such as "initial viscosity," "operation time," and "gel point" that directly guide the infusion cycle in the workshop; and 3. They have a single temperature path: they often use a constant temperature or linear ramp, making it difficult to simulate both the room-temperature infusion stage in the workshop and the high-temperature service period of the tire.

[0005] Academic research has attempted to use dynamic mechanical analyzers (DMA) to track the in-situ modulus of polyurethane foams or sealants. For example, "Dynamic Mechanical Analysis during Polyurethane Foaming" reported using DMA to monitor the evolution of the storage modulus during the foaming and curing of rigid foams. However, these studies focused on foaming systems or low-viscosity sealants, used a single test temperature, did not consider high-temperature strain sweeps, and did not simultaneously output the thermal safety index (tan δ) and the processing window. Summary of the Invention

[0006] In order to solve the above-mentioned technical problems, the purpose of the present invention is to provide a method for characterizing the process performance and heat generation performance of polyurethane materials for tire filling. This method adopts a three-stage in-situ rheology-DMA combined testing strategy to fill the gap in the existing technology that is unable to quickly and accurately evaluate the "process-performance-heat generation" coupled behavior of polyurethane fillers, and provide scientific and quantitative basic data support for formula development, production process control and tire thermal safety design.

[0007] In order to achieve the above-mentioned purpose, the present invention adopts the following technical solutions: A method for characterizing the processing performance and heat generation performance of a polyurethane material for tire filling comprises the following steps: 1) In-situ sample preparation: Component A and component B were thoroughly mixed in a planetary vacuum stirring deaerator at a preset mass ratio for 2-5 minutes to obtain a deaerated reaction mixture; 2) Rapid sample loading: 0.5-1 g of the mixture was placed in a DMA-Rheometer with parallel plates automatically maintaining a distance of 20-30 mm; 3) Three-stage in-situ curing-rheological test: Phase 1: Perform a 2-4h time scan at a constant temperature of 15-35°C to obtain the complex viscosity η* and loss factor tanδ in real time; Stage 2: Rapidly raise the temperature to 80-105°C and maintain constant temperature for 1.0-2.0h, continuing the time scan; The third stage: maintaining the temperature of the second stage, and performing a 0.1%-100% strain sweep on the cured sample; 4) Parameter determination: The η* value at t≈0 min is defined as the initial viscosity; The time corresponding to η*=10Pa·s is defined as the operable time; The time corresponding to tanδ=1 is defined as the gel point; At t = 270 min, η* is defined as the final modulus, and its corresponding tanδ is defined as the final loss factor; 5) Comprehensive thermal-process evaluation: The heat generation level of the filler is determined by the final loss factor, the on-site filling workability is comprehensively determined by the initial viscosity and operable time, and the tire load-bearing capacity is evaluated by the final modulus.

[0008] The tire core filler described in this invention comprises components A and B. Component A is primarily composed of a prepolymer or semi-prepolymer containing an isocyanate (–NCO) terminal, typically obtained by the partial reaction of a diisocyanate (such as toluene diisocyanate (TDI) or diphenylmethane diisocyanate (MDI)) with a polyether polyol (such as polyether triol or polyether diol). Component A exhibits excellent reactivity and controllability, providing the crosslinking phase for the formation of the polyurethane network structure. Component B is a mixture of polyols containing hydroxyl (–OH) functional groups and may contain chain extenders (such as ethylene glycol and dipropylene glycol), crosslinkers (such as trimethylolpropane), catalysts (such as tertiary amines), foam stabilizers, antioxidants, and masterbatches, among other additives, to control reaction rate, processing window, cell structure, and ultimate mechanical properties.

[0009] Preferably, the mass ratio of the A and B components is 1:1, and the temporary storage time allowed after a single mixing does not exceed 5 minutes.

[0010] Preferably, the temperature in the first stage is automatically switched in sequence using a three-point gradient of 15°C, 25°C, and 35°C.

[0011] As a preference, the temperature is increased by ≥5°C·min during the second stage of heating. -1 The temperature is raised to the target temperature at a rate of , and the heating process is included in the viscosity-time curve for inversion of the reaction exothermic peak.

[0012] Preferably, the strain sweep results of the third stage are used to calculate the ratio of the storage modulus G′ to the loss modulus G″ at 80° C., and to calibrate the dynamic-thermal coupling model at high temperatures.

[0013] Furthermore, the present invention also provides an in-situ characterization system for implementing the method, comprising: a) Planetary stirring and mixing unit with vacuum degassing and programmable speed; b) An integrated rheological-DMA test unit with 20-30mm automatic fixed-distance parallel plates and a temperature control range of 15°C-150°C; c) Data processing unit, whose built-in algorithm automatically identifies the three characteristic points η*=10Pa·s, tanδ=1 and t=270min and generates a comprehensive thermal-process evaluation report.

[0014] Preferably, the test unit is equipped with a fast film changing module so that the sample loading-testing interval is ≤30s.

[0015] Furthermore, the present invention also provides a computer device, comprising a memory, a processor, and a computer program stored in the memory, wherein the processor executes the computer program to implement the method described in the claim.

[0016] Furthermore, the present invention also provides a computer-readable storage medium having a computer program or instruction stored thereon, which implements the method when the computer program or instruction is executed by a processor.

[0017] Furthermore, the present invention also provides a computer program product, comprising a computer program or instructions, which implement the method when executed by a processor.

[0018] By employing the aforementioned technical solution, the present invention conducts three-stage, temperature-controlled, in-situ rheological-DMA testing of polyurethane components A and B within the same test sequence: room temperature infusion, curing phase, and high-temperature service phase. This avoids the sample inhomogeneity and data dispersion issues associated with traditional methods of post-curing slicing and testing. By real-time monitoring of the evolution of viscosity η* and loss factor tanδ, dynamic information from the initial reaction phase, gel transition, and final curing can be captured at the millisecond level, significantly improving measurement repeatability and accuracy. The inventive method directly reads five core parameters: initial viscosity, workable time, gel point, final modulus, and final loss factor, from a single viscosity-time / tanδ-time curve, providing a unified metric for raw material selection, equipment cycle time, and temperature field design. In particular, the workable time corresponding to η* = 10 Pa·s directly guides the workshop's infusion cycle time, avoiding incomplete filling due to overly rapid reactions or downtime due to overly slow reactions. The present invention avoids the problem of poor data repeatability caused by uneven sample curing while simultaneously obtaining process performance parameters. Based on the present invention, the variation and fluctuation of raw materials can be examined, production process conditions can be optimized, the product development cycle can be shortened, the machine tool mileage testing costs of actual finished tires can be saved, and a solid basic technical support can be provided for large-scale stable production. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 Schematic diagram of polyurethane material collapsing due to excessive heat generation.

[0020] Figure 2 Polyurethane filler test procedures and parameter interpretation diagram.

[0021] Figure 3 Result diagram of Example 1.

[0022] Figure 4 Result diagram of Example 2. DETAILED DESCRIPTION

[0023] The following is a clear and complete description of the technical solutions in the embodiments of the present invention in conjunction with the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts are within the scope of protection of the present invention.

[0024] 1. Test equipment and consumables part Model / Specifications Main Features Planetary vacuum stirring degassing machine THINKYARV-931 or equivalent device Complete vacuum degassing + homogenous mixing within 2-5 minutes Centrifuge tank 250mL aluminum alloy can with Teflon liner Carrying material A and B mixture Rheological-Dynamic Mechanical Analyzer TA Instruments ARES-G2 (25mm parallel plate) In-situ rheology + DMA combined testing Disposable sampling spoon 1mL (PTFE) Accurately and quickly extract 0.5-1g samples Data processing software RheoCompass®+ self-developed Python macro Automatic calculation of operating time, gel point, etc. 2. Methodology Reference Figure 2 The flow chart of the present invention shows that the method includes four steps: in-situ sample preparation → rapid sample loading → three-stage temperature control test → data processing.

[0025] 1. In-situ sample preparation Weigh 25g of each of component A and component B according to the preset mass ratio (typically 1:1, but can also be in the range of 40:60-60:40).

[0026] Pour both components into the centrifuge tank at the same time, cover tightly and place in the deaerator.

[0027] The program was set as follows: mixing speed 2000 rpm / reverse speed 1000 rpm, vacuum pump fully turned on, and run for 3 minutes.

[0028] Record the "degassing completion time t0" immediately after taking the product out of the can.

[0029] 2. Rapid sample loading Adjust the distance between the parallel plates of the ARES-G2 to 25 mm and set the normal force to 1 N. Use a disposable PTFE spoon to scoop 0.5-1 g of sample onto the center of the lower parallel plate. Lower the upper parallel plate until it touches the sample and hold it there. The time to complete sample loading should be ≤ 120 s (starting at t0). Record the time t1 when sample loading is complete.

[0030] 3. Three-stage temperature control test stage Temperature program model Duration I 15℃→25℃→35℃ (isothermal 1h×3) Time-Sweep, 1Hz, 10%γ 3h II Heat to 80-105℃ (typically 80℃), constant temperature Time-Sweep, 1Hz, 10%γ 1.5h III Maintain 80℃ Strain-Sweep, 1Hz, 0.1-100%γ 15min Phase I captures initial rheological behavior: η* at t≈0 is the initial viscosity η0; The t value when η*=10Pa·s is the operable time t op .

[0031] Phase II captures gel transition and exothermic peak: The t value when tanδ=1 is defined as the gel point t gel ; η* at t=t1+270min is recorded as the final modulus G f , tanδ is recorded as the final loss factor tanδ f .

[0032] Phase III calibrates the high-temperature dynamic modulus through strain scanning for use in the heat generation model.

[0033] 4. Data processing and judgment Software macro automatically outputs 〔η0,t op ,t gel ,G f ,tanδ f 〕Quintuple and complete curve.

[0034] Example 1: Effect of different ambient temperatures on process window Formula: Shanghai Huide Technology Co., Ltd. 7335D, A / B=1:1.

[0035] 1. Place component A and component B in a centrifuge tank at a ratio of 1:1 and mix them for 3 minutes using a planetary vacuum stirring deaerator at room temperature; 2. Take 0.5g of the mixed sample and place it on the 25mm parallel plate of ARES-G2 at room temperature. The loading time is 1.5min. 3. Test process: 1. Time-Sweep 1Hz, 10%, 3hrs, 15℃ / 25℃ / 35℃; 2. Time-Sweep1Hz,10%,1.5hrs,80℃ / 80℃ / 80℃; 3. Strain-Sweep1Hz, 0.1-100%, 80℃ / 80℃ / 80℃.

[0036] 4. Result analysis and evaluation: Figure 3 .

[0037] from Figure 3 It can be seen that the initial viscosity decreases with increasing temperature; the operable time is approximately 20 minutes at 25°C and 35°C, while it is 36 minutes at 15°C. The final modulus and loss factor data show that the workshop temperature has little effect on the final properties.

[0038] Example 2: Effect of different A / B mass ratios on thermal-process coupling performance Formula: Shanghai Huide Technology Co., Ltd. 7335D, A / B are set at 40 / 60, 45 / 55, 50 / 50, 55 / 45, and 60 / 40 respectively.

[0039] 1. Place component A and component B in a centrifuge tank at a ratio of 40:60, 45:55, 50:50, 55:45, and 60:40, respectively, and mix them for 3 minutes using a planetary vacuum stirring deaerator at room temperature; 2. Take 0.8g of the mixed sample and place it on the 25mm parallel plate of ARES-G2 at room temperature. The loading time is 2 minutes. 3. Test process: 1. Time-Sweep 1Hz, 10%, 3hrs, 25℃; 2. Time-Sweep1Hz,10%,1.5hrs,80℃; 3. Strain-Sweep1Hz, 0.1-100%, 80℃.

[0040] 4. Results Analysis and Evaluation Figure 4 .

[0041] from Figure 4 As can be seen, different ratios of A and B materials have different effects on product performance. When there is more B material, the reaction is significantly slower, the final modulus is lower, and the loss factor is higher, which is detrimental to product performance. Therefore, we strictly adhere to a 1:1 ratio during production.

[0042] The above is a description of the embodiments of the present invention. The above description of the disclosed embodiments will enable professionals in the field to implement or use the present invention. Various modifications to these embodiments will be apparent to professionals in the field. The general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but should conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for characterizing the process performance and heat generation performance of polyurethane material for tire filling, characterized in that: The following steps are included: 1) In-situ sample preparation: Component A and component B were thoroughly mixed in a planetary vacuum stirring deaerator at a preset mass ratio for 2-5 minutes to obtain a deaerated reaction mixture; 2) Rapid sample loading: 0.5-1 g of the mixture was placed in a DMA-Rheometer with parallel plates automatically maintaining a spacing of 20-30 mm; 3) Three-stage in-situ curing-rheological test: Phase 1: Perform a 2-4h time scan at a constant temperature of 15-35°C to obtain the complex viscosity η* and loss factor tanδ in real time; Stage 2: Rapidly raise the temperature to 80-105°C and maintain constant temperature for 1.0-2.0h, continuing the time scan; The third stage: maintaining the temperature of the second stage, and performing a 0.1%-100% strain sweep on the cured sample; 4) Parameter determination: The η* value at t≈0min is defined as the initial viscosity; The time corresponding to η*=10Pa·s is defined as the operable time; the time corresponding to tanδ=1 is defined as the gel point; at t=270min, η* is defined as the final modulus, and its corresponding tanδ is defined as the final loss factor; 5) Comprehensive thermal-process evaluation: The heat generation level of the filler is determined by the final loss factor, the on-site filling workability is comprehensively determined by the initial viscosity and operable time, and the tire load-bearing capacity is evaluated by the final modulus.

2. The method according to claim 1, characterized in that The mass ratio of the A and B components is 1:1, and the temporary storage time allowed after a single mixing does not exceed 5 minutes.

3. The method according to claim 1, characterized in that The temperature in the first stage is automatically switched in sequence using a three-point gradient of 15°C, 25°C, and 35°C.

4. The method according to claim 1, wherein In the second stage of heating, the temperature was raised to the target temperature at a rate of ≥5°C min⁻¹. The heating process was included in the viscosity-time curve for inversion of the reaction exothermic peak.

5. The method according to claim 1, wherein The strain sweep results of the third stage are used to calculate the ratio of the storage modulus G′ to the loss modulus G″ at 80°C and to calibrate the dynamic-thermal coupling model at high temperatures.

6. An in-situ characterization system for implementing the method according to any one of claims 1 to 5, characterized in that: include: a) Planetary stirring and mixing unit with vacuum degassing and programmable speed; b) An integrated rheological-DMA test unit with 20-30mm automatic fixed-distance parallel plates and a temperature control range of 15°C-150°C; c) Data processing unit, whose built-in algorithm automatically identifies the three characteristic points η*=10Pa·s, tanδ=1 and t=270min and generates a comprehensive thermal-process evaluation report.

7. The system according to claim 6, characterized in that The test unit is equipped with a fast film changing module, which makes the sample loading-testing interval ≤30s.

8. A computer device comprising a memory, a processor, and a computer program stored in the memory, wherein: The processor executes the computer program to implement the method according to any one of claims 1 to 5.

9. A computer-readable storage medium having a computer program or instruction stored thereon, characterized in that: When the computer program or instruction is executed by a processor, the method according to any one of claims 1 to 5 is implemented.

10. A computer program product comprising a computer program or instructions, characterized in that When the computer program or instruction is executed by a processor, the method according to any one of claims 1 to 5 is implemented.

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