1. Temperature control

When synthesizing the prepolymer, the temperature shall be controlled between 75-82 ℃. If the polyurethane elastomer equipment is high, the performance of the synthesized prepolymer will decline, and if it is low, the polymerization time will be extended. When mixed with MOCA, the temperature of the prepolymer is controlled between 90-110 ℃. Higher temperature will reduce the hardness and strength of the product, while lower temperature will increase the viscosity of the polymer, which is not conducive to the pouring operation. For polyurethane elastomer equipment, the curing time is controlled at 130 ℃. If it is high, MOCA will be decomposed, which is not conducive to crosslinking reaction and will increase other side reactions; Low will extend the molding time. The melting temperature of MOCA should be controlled when it is just melted into liquid, and the heating cannot continue, otherwise the color of liquid MOCA will become darker and decompose, affecting the product performance.

2. Time control

The synthetic reaction takes 2h, and intermittent vacuum pumping takes 2h. Then it is sealed and stored at room temperature. The synthesis of the prepolymer cannot exceed 4h at 75 ℃, and cannot exceed 2h at 100 ℃, otherwise the performance of the product will be reduced. Pouring shall be completed within 1-2min, because the stability period after mixing the prepolymer and MOCA is very short, generally only 4-5min, otherwise the mixture will not be able to be poured if it solidifies. The molding curing time is determined according to the shape and size of the product, generally between 15-30min, and the molding of the product shall be ensured. For large products, it takes longer, 2-3 hours.

3. Degassing of prepolymer

The quality of degassing is the key to the success of casting polyurethane elastomer. Generally, two links need to be controlled. After the prepolymer is synthesized, it will be degassed in vacuum at 75 ℃ when it is still, and most of the gas in the prepolymer will be removed; Before mixing the prepolymer with MOCA, it needs to be heated to 100-110 ℃ and degassed at high temperature; At the same time, vacuum (-0.095mpa) for degassing for 10min, then take it out and stir it to turn the bottom bubble to the top, vacuum for degassing for 10min, and then discharge the gas in the prepolymer completely before mixing with the curing agent to pour the product.

Guangdong Fuleite Electromechanical Technology Co., Ltd., located in the Industrial Zone, No. 39, Tongfu Middle Road, Nantou Town, Zhongshan City, Guangdong Province, is a polyurethane mechanical automation production enterprise integrating R&D, production, sales and after-sales service. Our company specializes in developing and manufacturing various polyurethane foaming machines, cyclopentane foaming machines, automatic foaming production lines (suspension lines/ground rails/disk lines, etc.), automatic foaming mold frames, mechanical arms and other complete sets of polyurethane foaming equipment, helping thousands of polyurethane product production enterprises to achieve "high product excellence rate and low equipment failure rate".