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MDI (coarse MDI) selection for self skinning

2020-07-14 16:52:57
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Polyurethane self formed foam (self-skinning foam), also known as whole skin foam (integral skin skin foam, referred to as ISF foam), was first developed by the British Shell Chemical Company [1]. It does use other plastics as the surface material, relies on foaming components to form a tough, compact elastic skin layer a soft core foam material. It has the advantages of good elasticity, impact resistance wear resistance. A kind of

Self forming foam usually consists of two components, polyols, crosslinking agents, catalysts, foaming agents, emulsifiers, colorants, sometimes mixtures of flame retardants, etc., which form the A component of the self forming foam system. Component B consists of isocyanate components, mainly including liquefied MDI, crude MDI polyurethane modified MDI their blends. MDI modified by urethane has excellent fluidity, excellent mechanical properties comfortable handle. Isophorone diisocyanate (IPDI) must be used for light colored, light resistant soft self foam, but combined with special catalysts. A kind of

In this paper, the fluidity product performance of modified MDI isocyanates in self skinning formula were compared in detail, a full water self skinning system based on Beijing Keju modified MDI wannate8629 was developed

2. Experiment

2.1 raw materials equipment

Hc-6001: NCO%: 26.8; viscosity (25 ℃): 250Mpa. S

Crude MDI: NCO%: 31.4; viscosity (25 ℃): 208mpa. S

Liquefying MDI: NCO%: 29.0; viscosity (25 ℃): 40MPa. S

Ppg330n: ethylene oxide end capped, hydroxyl value 33 ~ 37mgkoh / g

Pop3630: polymer polyol: hydroxyl value 25-29 mgKOH / g

Chain extender

Catalysts foam stabilizers

Foaming agent 141b

2.2 test instrument:

Aluminum mold

Foaming machine

Electronic testing machine

Infrared thermometer

Shore hardness LX-A

2.3. The mechanism of skin formation self forming foam.

There are many different theories about the formation principle of polyurethane self foam. Whitman[1] proposed that the heat loss of heat conduction mold can make the foaming agent close to the mold surface vaporize form the epidermis. Wirtz[2] suggested that the foaming agent should maintain the liquid state on the surface of the mold adjacent to the foam when the foaming viscosity increased, then the foaming agent was dispersed the skin area to the foam core, thus forming a bubble free boundary zone. Grieve[3] proposed that foam material as insulation can make the foaming of central materials easier. In addition, due to the excessive filling of the mold, the internal pressure is increased, the boiling point of the foaming agent is increased, thus preventing the foaming foaming of the foaming agent on the adjacent mold surface.


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