1. What is rigid foamed polyurethane?
Rigid foamed polyurethane is a new type of waterproof and thermal insulation material, which is composed of polyisocyanate (MDI, commonly known as black pigment) and mixed foaming agent, catalyst, modifier, flame retardant, anti-aging agent and other polyols (commonly known as white materials). It has continuous and dense surface layer and interconnected wall high-strength honeycomb structure with a closed cell rate of more than 95%. It is a new energy-saving material with multiple functions such as waterproof, heat preservation, heat insulation, gas insulation and anti-corrosion. Rigid polyurethane foam has been used for more than 30 years in developed countries in Europe and the United States.
2. Why use rigid foamed polyurethane as the insulation material of thermal insulation pipeline?
a. Low thermal conductivity, thin thickness and space saving
b. Seamless joint, no cold leakage, low cost
c. Easy maintenance. BASF low temperature material formula can be used for maintenance and construction under the operation of heating pipe network without affecting the normal use.
d. Anti enzyme and moisture
3. What is the service life of rigid foamed polyurethane?
The long service life of rigid foamed polyurethane is determined by its excellent chemical compatibility, dimensional stability, high closed cell rate and low water absorption.
Rigid foamed polyurethane is a plastic foam with stable structure and high obturator rate produced by the mixture reaction of two components of polyols and isocyanates. Rigid polyurethane foam, stable properties, compatible with most chemical materials, chemical corrosion resistance.
Rigid foamed polyurethane has high compressive strength, which is not easy to cause perforation and thinning of polyurethane insulation layer caused by external force.
The thermal conductivity of polyurethane itself is stable. With the increase of service time, its thermal conductivity value changes little, and it is stable at about 0.024 w / (m.k). The thermal insulation performance of the system is not affected obviously.
4. How to choose high quality rigid foamed polyurethane?
From two aspects of raw materials and finished products. The quality of black and white materials directly determines the quality of finished products, while the technology and production strength determine whether the manufacturer can provide high-quality and reliable raw materials. 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 spray hard foam polyurethane with low thermal conductivity and low closed cell rate, and the performance indexes of the finished products meet and exceed the national specifications.
5. Why is the price of some rigid foamed polyurethane in the market especially low?
There are two kinds of low price rigid foamed polyurethane: one is that TDI by-product is mixed into MDI. TDI and MDI isocyanate series products, TDI used to make flexible polyurethane foam. When TDI is produced, a kind of residual by-product will be produced. If this by-product is not used, it needs to be burned and destroyed, so the price is very low. Mixing the by-product in black MDI can greatly reduce the cost of raw materials. However, the hard foam polyurethane finished products turn dark yellow, foam becomes crisp, thermal conductivity increases greatly, and moisture absorption is easy.
Another situation is the large use of recycled materials in white materials. Or it is to recycle the expired white materials for reprocessing, or it is to use the recycled materials as raw materials to produce white materials. The use of recycled materials will lead to the increase of density, the decrease of closed cell rate, the increase of thermal conductivity and the deterioration of dimensional stability.
6. Why is the quality of some heating and insulation pipes unstable?
Two factors need to be considered in heating and insulation pipeline, which are heat exchange and moisture exchange. If the dimension stability of rigid foamed polyurethane is not good and the construction process is not correct, it will cause the rigid foamed polyurethane cracking after the thermal insulation pipeline is put into use, and form cold bridge leakage. If the rigid foam polyurethane closed porosity is too low, it will result in foam opening and moisture absorption. The thermal conductivity of foam will rapidly increase after moisture absorption, and the cooling effect will be greatly reduced.