1. What is sprayed rigid polyurethane?
Sprayed rigid polyurethane is a new type of waterproof and thermal insulation material made of polymer by mixing isocyanate (MDI, commonly known as black material) and polyol (commonly known as white material) with a variety of additives such as blowing agent, catalyst, modifier, flame retardant and anti-aging agent, etc. It is uniformly mixed by special equipment according to a specific ratio, sprayed at high pressure and formed by fluorine-free foaming on site. It has a continuous dense surface layer and a high strength honeycomb structure with interconnected walls with a closing rate of more than 95%, and is a new energy-saving material with various functions such as waterproof, heat insulation, heat preservation, air insulation and corrosion prevention. Rigid foam polyurethane has been used in developed countries in Europe and America for more than 30 years, and the application is quite popular.
2. Why do you choose sprayed rigid polyurethane as the insulation material of cold storage enclosure?
a. Low thermal conductivity, thin thickness, space saving
b. Seamless joint, no cold leakage, low cost of use
c. Easy maintenance. BASF low temperature material formula, can be in the cold storage operation under the maintenance construction, does not affect the normal use, to avoid the switch cold storage energy consumption
d. Anti-enzyme, moisture-proof
3. What is the service life of sprayed hard foam polyurethane?
The excellent chemical compatibility, dimensional stability, high porosity and low water absorption of polyurethane sprayed hard foam determine its long service life.
Rigid polyurethane is a plastic foam with a stable structure and high closed-cell ratio produced by the reaction of two components: polyol and isocyanate. Rigid polyurethane is stable in nature, compatible with most chemical materials and resistant to chemical corrosion.
Rigid polyurethane has good dimensional stability and can be used for a long time at temperatures from -200℃ (LNG storage tanks and pipelines) to 130℃ (high-pressure steam heat pipelines) with dimensional changes of less than 1%.
Rigid foam polyurethane has high compressive strength, which is not easy to produce problems such as perforation and thinning of polyurethane insulation layer caused by external damage.
Polyurethane itself thermal conductivity is stable, with the increase in use time, its thermal conductivity value changes very little, stable in 0.024 W / (m?K) or so, the system insulation performance is not significantly affected.
4. How to choose the high quality sprayed rigid polyurethane?
From the raw material, finished product two aspects of comprehensive measurement. The quality of black and white materials directly determines the quality of the finished product, while the technology and production strength determines whether the manufacturer can provide high quality and reliable raw material products. Well-known enterprises will not use recycled materials as raw materials to produce white materials to ensure the quality of finished products. At the same time, manufacturers with advanced technology and strong R&D strength can develop and produce sprayed rigid polyurethane with low thermal conductivity and low porosity, and the performance indexes of finished products in all aspects meet and are better than the national specification requirements.
5. Why is the price of some sprayed rigid polyurethane in the market particularly low?
TDI and MDI isocyanate series products, TDI is mostly used to make soft foam polyurethane. The production of TDI produces a residual byproduct, which is incinerated and destroyed if not used, so the price is very low. Mixing this by-product in the black MDI can greatly reduce the cost of raw materials, but the color of the finished sprayed hard foam polyurethane becomes dark yellow, the foam becomes crispy, the thermal conductivity increases significantly, and it is easy to absorb moisture.
Another situation is that a lot of recycled materials are used in white materials. Or recycling expired white material and then processing, or using recycled material as raw material to produce white material. The use of recycled materials will cause the finished hard foam polyurethane density to increase, the closed porosity to decrease, the thermal conductivity to increase, and the dimensional stability to deteriorate.
6. Why some cold storage use a period of time after the leakage of cold, refrigeration machine electricity costs increased?
Cold storage requires consideration of two factors, which are heat exchange and moisture exchange. If the size stability of the sprayed rigid polyurethane used is not good and the construction process is not correct, it will cause the cold storage to cool down and put into use after the sprayed rigid polyurethane cracks, forming a cold bridge to leak cold. If the closed-hole rate of sprayed rigid polyurethane is too low, it will cause the foam to open and absorb moisture, and the thermal conductivity of the foam will rise rapidly after absorbing moisture, and the effect of cold preservation will be greatly reduced.
7. How much electricity can be saved by using high quality sprayed rigid polyurethane in cold storage?
In South China, for example, the average outdoor temperature is 22℃, the temperature of cold storage is -30℃, and the energy consumption ratio of refrigeration equipment is 2. A 5,000 square meters cold storage with 0.022W/(m*K) thermal conductivity of sprayed rigid polyurethane saves about 66,900 units of electricity per year than 0.034W/(m*K) sprayed rigid polyurethane, saving 35% of electricity consumption. The reduction in electricity consumption has positive implications for saving on electricity bills and reducing the risk of being limited during peak electricity consumption periods.
