。 As thermal insulation materials, Rigid Polyurethane Foam for its very low thermal conductivity and to facilitate the forming process, in many areas with an irreplaceable position.  However, as a response to the polymer molding, molding shrinkage (response after the completion of forming the bubble is smaller than the process of forming the largest volume) inevitably become one of its main deficiencies.  Forming contraction of the existence of, and often makes foam filled by the end smaller than the cavity size, a housing bubble and peeling, a serious impact on the appearance of products, insulation effect or even life.  Therefore, in most applications, polyurethane insulation layer often filled by increased density foam, to molding the way to resolve this problem.

 Solar water heaters because of their unique structure (the thin shell and the interior, the complex shape of the mouth) and the inconvenience to molding, and high density will also increase the cost filled, the use of relatively high density of the free Foam filled, solar water heaters to the defects are: foam layer and shell out, foam extrusion molding shell, interior lead to deformation, especially over defects in the mouth when the collector is particularly serious, causing a large number of technology Defective.
 In a wide range of research on the basis of understanding to: not to increase the density foam filled on the basis of forming a bubble at the lower rate of contraction is the solar water heater materials of the key. From this formula, material, and so proceed, developed a solar water heater to a combination of materials, the solar water heater production in some of the online trial achieved satisfactory results: foam and the degree of light shell peeling, the interior Shell deformation risk greatly reduced.

 Components and formula
 Special polyether polyol: 100
Surfactants: 1.5-3
    1 Special catalyst: 1.5-2.5
      Foam: 20-30
ISO/POL：       1:1 ISO / POL: 1:1

Information technology performance parameters

       Mixing foam foam injection molding machine

s                ≥20            10-20 Rubai time s ≥ 20 10-20
s                70-120           70-80 Gel time s 70-120 70-80
min              ≤5              ≤5 Curing time min ≤ 5 ≤ 5

 Information and performance indicators) free foam)
：ΔV≤2% Filling density :28-45 kg/m3 compressive strength (10%): ≥ 160 kpa thermal conductivity: ≤ 0.023 w / mk-stable (70 ℃, 48 h): Δ V ≤ 2%

 Caution ① the best use of foam material adjustment in the temperature of 20 ± 3 ℃ to ensure that the system is the appropriate reaction performance; ② foam should be strictly in accordance with the requirements established that the use of white and black material proportion of materials to ensure that the system Process performance; ③ daily production use should be preceded inspection equipment and materials) through the gun-free foam injection verification); ④ Do not allow water contact with the material in the production site to the attention of ventilation.