In order to save energy and "keep out the cold", "put on" thermal insulation coatings for buildings

In the cold winter, building roof and wall insulation have become the focus of attention. At present, nearly 2 billion square meters of new buildings are newly built every year in my country, which is more than the total construction volume of all developed countries, but more than 95% of buildings are still high-energy-consumption buildings. Building wall insulation is mainly through taking measures in the building and outer protective structure to reduce the indoor heat dissipation of the building to the outdoors and maintain the indoor temperature. If you put a "coat" on the building - building thermal insulation coating, it can not only create a comfortable indoor thermal environment, but also achieve the purpose of energy saving, which is an effective means of "protecting against the cold" in buildings.

1. Different principles to achieve thermal insulation

Building thermal insulation coatings achieve thermal insulation through low thermal conductivity and high thermal resistance. External wall thermal insulation coatings are mainly divided into two categories, one is the thick external thermal insulation system, which uses the barrier principle of reducing heat transfer, such as rubber powder polystyrene particles thermal insulation, inorganic glass beads thermal insulation, etc., with obvious effects; the other type It is a thin-layer coating, which uses the principle of reducing sunlight absorption to reduce the intrusion of external solar energy and achieve the purpose of heat insulation. According to the thermal insulation mechanism, thermal insulation coatings can be divided into three categories: barrier thermal insulation coatings, reflective thermal insulation coatings and radiation thermal insulation coatings.

Barrier thermal insulation coating is a kind of coating that realizes thermal insulation through low thermal conductivity and high thermal resistance. The most widely used barrier thermal insulation coating is composite silicate thermal insulation coating. This type of coating was developed in the late 1980s and has different product names, such as composite magnesium aluminum silicate thermal insulation coating, rare earth thermal insulation coating, coating type composite silicate thermal insulation coating, etc. It is a thermal insulation coating made of inorganic and organic binders, thermal insulation aggregates (such as sepiolite, vermiculite, perlite powder, etc.) and air-entraining agents. Although the thermal conductivity is low and the cost is low, the drying cycle is long and the impact resistance is weak.

Reflective thermal insulation coatings are developed on the basis of aluminum-based reflective thermal insulation coatings. By selecting appropriate raw materials and formulas, high reflectivity coatings are made to reflect sunlight to achieve thermal insulation purposes. Thin-layer reflective thermal insulation coatings are representative of this type of coatings. It consists of base material, heat-reflecting fillers and additives. The thermal reflectivity of the thin-layer thermal insulation reflective coating is high, generally above 80%, and the thermal insulation effect is obvious. However, due to the relatively thin coating film thickness, the total thermal resistance is limited, and the thermal insulation effect is not large, so it can be used in conjunction with other thermal insulation materials. The new space energy-saving reflective thermal insulation coating integrating high efficiency, thin layer, thermal insulation, decoration, waterproof, fire prevention, anti-corrosion and insulation can effectively inhibit the radiant heat and conduction heat of the sun and infrared rays, and the thermal insulation inhibition efficiency can reach 90% or so.

Radiation thermal insulation coating is to transmit the solar energy absorbed by the building into the air in the form of radiation in the form of long wave, so as to achieve the effect of thermal insulation. Radiation thermal insulation coating can radiate the absorbed heat in the form of thermal emission, so as to keep indoor thermal insulation and achieve thermal insulation effect. Combined use is better. As an interior wall coating, low reflectivity at room temperature is conducive to improving comfort and energy saving.

2. Technology improves performance

The author believes that according to the climatic characteristics of different regions, we should formulate a scheme combining external wall thermal insulation, and reasonably select and use various thermal insulation coatings. In my country, the more mature and recommended external wall thermal insulation systems are: polystyrene board thin plaster external wall external thermal insulation system, rubber powder polystyrene particle thermal insulation slurry external wall thermal insulation system, cast-in-place concrete composite Mesh polystyrene board external wall external thermal insulation system, cast-in-place concrete composite polystyrene board steel wire mesh board external wall external thermal insulation system, mechanically fixed polystyrene board steel wire mesh board external wall external thermal insulation system. In addition, rock wool, polyurethane, extruded polystyrene board and other external wall thermal insulation systems have also been developed and applied to a certain extent. In the field of building energy conservation in European and American countries, the currently widely used external wall thermal insulation systems are mainly thin plastering methods with external thermal insulation boards. There are two thermal insulation materials: flame retardant expanded polystyrene board and non-combustible rock wool board. All use paint as exterior finish.

With the development of society, the continuous improvement of living standards and the continuous advancement of science and technology, the performance requirements for building thermal insulation coatings are also continuously improved. At present, the relatively good exterior wall thermal insulation coatings have good weather resistance, low thermal conductivity, stable thermal insulation performance, high softening coefficient, freeze-thaw resistance, and anti-aging; the base layer has strong adaptability to deformation, and can effectively prevent the generation of wall cracks; The system has no cavity, strong resistance to negative wind pressure, and is suitable for multi-storey and high-rise buildings; good air permeability, strong breathing function, good waterproof function, and can discharge the moisture of the insulation layer; convenient construction and fast speed, It can be constructed at multiple points and at multiple levels; the fire resistance level can reach B1 level and above.

With the development of science and technology, some new thermal insulation coatings are applied in buildings. For example, there is a thermal insulation coating made of a special solution with a thermal conductivity of only 0.03 W/m. Just paint a thin 3mm on the interior of the building to raise the room temperature in winter by more than 3 degrees Celsius. Nano thermal insulation coating is based on synthetic resin emulsion, and is made of hollow ceramic powder with high reflectivity and large thermal resistance. It has low thermal conductivity and high reflectivity, and has a good development prospect. The use of vacuum fillers to prepare thermal insulation coatings with excellent performance has also become one of the current research hotspots.

The development and production of composite multi-functional thermal insulation coatings is also the future development direction. Because a coating with good thermal insulation effect is often the result of the synergy of two or more thermal insulation mechanisms, various thermal insulation coatings have their own characteristics and can be compounded to achieve complementary advantages and develop composite materials with excellent performance. Type thermal insulation coating. Combining different thermal insulation coatings and thermal insulation materials, it can be made into an external wall external thermal insulation system that is both thermal insulation and thermal insulation, or an external wall external thermal insulation system mainly based on thermal insulation, which can meet the needs of hot summer and cold winter areas and summer. The need for building energy conservation in areas with hot winters and warm winters is also the development trend of building exterior insulation.