1. What is sprayed rigid foam 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, anti-aging agent, etc., mixed uniformly according to a specific ratio by special equipment, 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 polyurethane has been used for more than 30 years in developed countries in Europe and America, and its 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. Low-temperature material formula, you can repair construction in the cold storage operation, 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 stable structure and high closed-cell ratio, which is 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 ranging 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 force damage.
Polyurethane itself thermal conductivity is stable, with the use of 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 companies 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 the finished products meet and are better than the requirements of national specifications.
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 density of finished rigid polyurethane foam to increase, the closed porosity to decrease, the thermal conductivity to increase, and the dimensional stability to deteriorate.
6. Why do some cold stores leak after a period of time and increase the electricity cost of the refrigerator?
Cold storage needs to consider two factors, is the heat exchange and moisture exchange. If the size stability of the sprayed polyurethane is not good and the construction process is not correct, it will cause the sprayed polyurethane to crack and form a cold bridge after the cold storage is cooled down and put into use. 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.
