All-water polyurethane foam
All-water polyurethane foam, also known as all-water foamed polyurethane foam, is an environmentally friendly and green filling material. It completely uses water as the foaming agent, which is non-toxic, tasteless and non-damaging to the ozone layer, realizing a completely environmentally friendly construction process, as well as having good sound insulation, heat preservation and moisture-proof performance.
I. Principle of all-water polyurethane foaming
The chemical reaction between water and polyisocyanate generates carbon dioxide gas, which stays in the bubble holes, causing the viscoelastic foam material to expand, foam, and solidify, and ultimately forming polyurethane foam.
Advantages of all-water polyurethane foaming
Environmental protection: Due to the use of water as the foaming medium, no organic solvent is used, which reduces the pollution to the environment. The gas produced in the foaming process is mainly CO2, which is harmless to human body. And produce very little CO2, CO2 ODP value is zero, the ozone layer of the atmosphere has no destructive effect, the impact on the environment is negligible, is the most environmentally friendly blowing agent.
Safety: all-water foaming does not use physical blowing agent, no flammable and explosive toxic hazardous materials, suitable for a variety of conditions and complex environments in the construction and use of thermal insulation.
Low cost: the cost of raw materials is relatively low, suitable for mass production.
Simple process: all-water foaming does not require special modification of the original HCFC-141b equipment and has no special requirements, and is easy to operate and control. The combination of polyether does not contain low boiling point blowing agent, can be used in a higher temperature range, not affected by temperature and environment, lower economic costs.
Third, all-water foaming polyurethane foam classification
Full water-blown rigid polyurethane foam: with high density and hardness, it is suitable for application scenarios that require high load-bearing capacity, such as building insulation, industrial equipment insulation, etc. It is also used in the manufacture of polyurethane foam. Its manufacturing process is simple, fast and environmentally friendly, and it has better thermal insulation and corrosion resistance.
Flexible water-blown polyurethane foam: soft, with good elasticity and sound-absorbing properties, suitable for applications that require good sound insulation and buffer, such as automotive interiors, furniture filling, etc., and its manufacturing process is also relatively simple, fast and environmentally friendly.
Fourth, the development trend of all-water polyurethane foam and technical improvement
In order to improve the performance of all-water foaming foam and change its shortcomings, some related companies at home and abroad have carried out a lot of research work. After years of practical development and research, the whole water foaming polyurethane composites and foams on the market at present are roughly as follows.
(1) High isocyanate index foam
The combined polyether of the all-water foaming compound consumes more polyisocyanate components (black material) than the HCFC-141b foaming system. In order to improve the strength and temperature resistance of the foam, especially in the polyurethane pipe insulation, need to use a higher isocyanate index of the formula, the amount of black material needs to be more, polymerization MDI index of 150 ~ 160 (isocyanate index 1.5 ~ 1.6) use more.
(2) Open cell aqueous foam
In order to reduce the polymerization MDI index to the range of 100 to 120, and at the same time to ensure that the foam does not shrink in the use of temperature range, you can appropriately increase the open cell ratio of the whole water foam. However, the thermal conductivity and water absorption rate of such foam are very high, which is not suitable for the case of good thermal insulation effect.
(3) Whole water foam with high closed cell and low isocyanate index
By improving the molecular structure of polyether and the performance of organosilicon leveling agent, it can ensure both high closed cell ratio and good pore strength, and under low polymerization MDI index (around 100), the foam has better heat resistance, low temperature resistance and lower thermal conductivity. This is also a more ideal technology for replacing HCFC-141b with water-blown polyurethane in the future.
(4) Foam foaming
In recent years, there is also the use of liquid CO2 and water and foaming method, this foaming method is commonly known as foam foaming, that is, CO2 as a physical blowing agent and water as a chemical blowing agent way to improve the mobility of foaming, the bubble holes in the case of microfine can reduce the thermal conductivity of the foam, improve the performance of the foam.
V. Cost and environmental benefit analysis
Compared with the whole water foaming before substitution, each ton of combined polyether reduces the usage of 200kg of HCFC-141b (calculated according to each ton of combined polyether containing 20% blowing agent), and according to the calculation of 10,000t of combined polyether per year, the usage of 2,000t of HCFC-141b can be reduced every year. Unlike the conventional all-water foaming combination material with black and white ratio of 1.2~1.8/1, the black and white ratio of the combination material developed by our company is about 1/1, so that there is no increase in the cost caused by the polymerization of more MDI dosage. The water used in all-water polyether can be used without cost, but the cost of all-water polyether is higher than the cost of ordinary polyether by about 1,000 yuan/t. HCFC-141b has a high market price at present, and the adoption of this all-water foaming technology can reduce the cost and have better economic benefits.
Sixth, the application field
1. construction field: used for heat insulation, filling and sealing, such as building wall insulation, roof insulation, door and window sealing.
2. automobile field: it can be used to manufacture car body, seat and other parts to provide cushioning, sound insulation, heat insulation and other functions.
3. Furniture field: used in the manufacture of upholstery, mattresses, etc., to increase comfort and elasticity.
4. Packaging field: used as packaging material to protect products from shock and vibration.
