Polyurethane rigid foam foaming technology and application

1. Advantages of foamed polyurethane

Foamed polyurethane is composed of two components, component A is polyol and component B is isocyanate. During construction, the two components enter the spraying machine and are mixed and sprayed out in the form of mist. Bubble solidification molding. This material has only been introduced in recent years. It has been used for building insulation and waterproofing for two or three years. It has been widely understood and has many advantages and a wide range of uses. 1. Good thermal insulation performance. The thermal conductivity is about 0.025, which is better than polystyrene board. It is currently the best material for building insulation. 2. Good waterproof performance. The foam holes are closed, with a closing rate of 95%, and rainwater will not seep through the holes. 3. Due to on-site spraying, an overall waterproof layer is formed without seams, which is unmatched by any polymer membrane, reducing the maintenance workload. 4. Good bonding performance. It can be bonded very firmly to wood, metal, masonry, glass and other materials, and is not afraid of being lifted up by strong winds. 5. It is suitable for new roofs or old roof repairs, especially for old roof repairs. It is not necessary to remove the original waterproof layer and insulation layer. You only need to remove the dust, sand and debris on the surface before spraying. 6. Construction is simple and fast. Each job can spray more than 200 square meters per day, which is conducive to progress. 7. The closing structure is simple. Spray foaming polyurethane to close the ends, no special treatment is required, which is greatly simplified. If roll material is used, a groove must be left at the parapet and the end must be closed in the groove; if the groove cannot be left, a flat iron seal must be used to close the end and caulking paste must be applied. 8. Good economic benefits. If the insulation layer and waterproof layer are separated, not only the cost will be high, but also the construction period will be long, while foamed polyurethane will survive at one time. 9. Good aging resistance. According to foreign engineering summaries and research tests, the aging resistance can reach 30 years.

2. Foamed polyurethane Application

1. If the flat roof is waterproof and thermally insulated, spray a layer of colored paint as a protective layer on the upper roof; on the upper roof, slurry the paving tiles.
2. For sloping tile roofs, spray foamed polyurethane on the lower edge of the balustrade, and the tiles will be seated on the balustrade to avoid sliding. 3. Wall insulation foamed polyurethane is more superior when used as wall insulation. For matching large wall panels, spray them between the ribs of the panels for good and tight bonding. If hollow blocks are used, foamed polyurethane can be sprayed into the holes to fill the walls of the freezer, especially spraying. At present, the key to wall reform is insulation technology, and foamed polyurethane can make great achievements. 4. The insulation and waterproofing of the exterior wall of the basement is where foamed polyurethane comes into play. It can not only maintain insulation and waterproofing, but also eliminate the need for other protective layers, killing two birds with one stone.

3. Foamed polyurethane Disadvantages

Although foamed polyurethane has so many advantages, it is not a panacea and has shortcomings and inadequacies. 1. At temperatures above 10°C, the foaming rate decreases. Therefore, use is obviously subject to seasonal restrictions. 2. Toilets and bathrooms only need to be waterproof but not thermally insulated. Foaming polyurethane is not suitable. 3. Foamed polyurethane spray molding is fast, and it is not easy to spray it very smoothly. It is normal to be uneven. It is used for roof waterproofing and thermal insulation. The flatness can be relaxed, but the flatness of eaves and gutters is not good, which will affect the drainage flow rate. Therefore, it needs to be used in conjunction with other waterproof materials. Its usage in polyurethane products is second only to polyurethane soft foam.

Polyurethane rigid foam is mostly closed-cell structure, with excellent thermal insulation effect, light weight, high specific strength, and convenient construction. It also has sound insulation, shockproof, electrical insulation, heat resistance, cold resistance, Due to its solvent resistance and other characteristics, it is widely used in the box insulation layer of refrigerators and freezers, insulating materials such as cold storages and refrigerated trucks, as well as insulating materials for buildings, storage tanks and pipelines. It is also used in small quantities in non-insulated situations, such as imitation wood, packaging materials, etc. Generally speaking, lower density rigid polyurethane foam is mainly used as thermal insulation (thermal insulation) material, and higher density rigid polyurethane foam can be used as structural material (imitation wood). Polyurethane rigid foam is generally foamed at room temperature, and the molding process is relatively simple. According to the degree of mechanization of construction, it can be divided into manual foaming and mechanical foaming; according to the pressure during foaming, it can be divided into high-pressure foaming and low-pressure foaming; according to the molding method, it can be divided into pouring foaming and spray foaming.