The ultra-low temperature freezer adopts polyurethane as thermal insulation material. It is important to choose correct insulation material to thermal insulation for the ultra-low temperature freezer. At this point, the importance of insulation materials will be revealed. Suitable insulation materials can minimize the impact of the atmosphere on the temperature in the freezer and minimize the consumption of electricity. The following will be though the insulation performance, dimensional stability and service life these three aspects to choose the appropriate insulation materials.
- Insulation performance
The first requirement of choosing insulation material is insulation performance. However, the thermal insulation performance can not be visible to the naked eye before the formal use. However, it is too late to notice the difference in power consumption. Therefore, it is necessary to pass a lot of experimental inspection and strictly control the material selection according to the following standards, so as to ensure the insulation performance.
- Check whether the thermal insulation material adopts structural amine ether, which can reduce the thermal conductivity and improve the thermal insulation effect.
- check whether the water content is reduced in various raw materials and formulations to avoid deterioration of insulation performance caused by water foaming.
- Check whether choose a brand that has been treated strictly. This kind of foam has higher uniformity, thinner wall and better thermal insulation performance than the ordinary foam with large wall thickness produced by small factories without treatment.
- Check whether the use of efficient odorless amine catalyst can effectively adjust the balance of foaming and gel reaction, so that the coating layer is thinner, conducive to the performance of the cold storage insulation materials.
This control can be quite effective, and the power consumption of the cold storage using this kind of insulation material is much lower than that of others.
- Dimensional stability
The thermal insulation materials in the cold storage in the drastic temperature change or long-term low temperature will appear size change, generally is shrink. The change of size may cause the foam to crack or fall off, thus affecting the normal use of the cold storage. Therefore, in the choice of insulation materials, not only to test the performance, but also to pay attention to the choice of high-quality materials.
The particular high degree of functionality polyether compound application makes the foam form three-dimensional network structure and greatly improves the low temperature resistance of the foam. However, at present, 4110 polyether commonly used in coating spray contains a large number of difunctional components, and forms a large number of linear grouping structures after reaction, which is difficult to be stable at low temperature. However, the dimensional stability of the foam can be greatly improved by using high functional crosslinking agent.
Polyether is catalyzed by strong base in the production stage, the reaction is thorough, and the reaction rate is high. In order to make the appearance of foam does not deform, some manufacturers add openable components to the foam material to reduce the closed pore ratio of foam and achieve the effect of stable size but at the expense of insulation performance.
- Service life
In the selection of appropriate insulation materials, in addition to considering the basic properties of the foam at the initial stage, performance aging is also a very important aspect. Although some polyester foams have good toughness and impact resistance, they become brittle after being used for some time at low temperatures. In addition, the poor hydrolysis resistance of some polyester materials will also affect the service life of the foam. However, after the polyether structure is adopted, although the brittleness is a little bit at the initial stage, it will disappear after a few days, and the properties of the insulation materials in the cold storage will be kept stable for a long time.