发泡料经过经过聚氨酯高压发泡机混合注入保温腔体或壳体夹层，在未固化前须流经相当长的距离才能充满，充满后整个泡沫的密度、孔结构、强度及导热系数的分布有显著差异，存在明显的梯度。流动性就是表征发泡体系在发泡过程中克服阻力均匀充满各种复杂保温腔体或壳体夹层的能力。从本质讲，聚氨酯发泡是一个复杂的物理和化学过程，几乎同时发生着链增长、发泡及交链三类基本反应。反应初期(乳白期)主要是线形分子的链增长，反应热少，有少量发泡气体的产生或汽化，此时料液起发产生微小膨胀，同时由于粘度较小料液产生物理流动，故表现出一定程度的流动性，但不十分显著;随着反应的继续，放热量进一步增大，大量发泡剂的汽化引起泡沫体的急剧膨胀(发泡期)，此时泡沫的膨胀所引发流动充满大部分腔体;当出现凝胶也就是大分子开始交链(固化期)时，发泡体系粘度的陡然增加使泡沫与腔壁摩擦增大，虽然在内压的作链(固化期)时，发泡体系粘度的陡然增加使泡沫与腔壁摩擦增大，虽然在内压的作用下轻微膨胀，但边界效应使得泡沫体的泡孔拉伸变形，呈现强烈的各向异性，这一段泡沫体因此也极易收缩变形。

        广东弗雷特机电科技有限公司位于广东省中山市南头镇升辉北工业区，是一家集研发、生产、销售、售后服务于一体的聚氨酯机械自动化生产型企业。我司研发制造各类聚氨酯浇注机、聚氨酯发泡机、自动化发泡生产线（悬挂发泡线/地轨发泡线/转盘线等）、自动化发泡模具模架、机械臂等聚氨酯成套发泡设备，帮助上千家聚氨酯制品生产型企业用户达到“制品优良率高，设备故障率低”。

Do you know the basic process of polyurethane foaming in refrigerators?

The foaming material is mixed and injected into the insulation cavity or shell interlayer through a polyurethane high-pressure foaming machine. Before it is cured, it must flow for a long distance to be filled. After filling, the density, pore structure, strength and thermal conductivity of the entire foam are distributed. There is a significant difference, there is a clear gradient. Fluidity is to characterize the ability of the foaming system to overcome the resistance and evenly fill various complex thermal insulation cavities or shell interlayers during the foaming process. Essentially, polyurethane foaming is a complex physical and chemical process, and three basic reactions of chain growth, foaming and cross-linking occur almost simultaneously. The initial stage of the reaction (milk white stage) is mainly the chain growth of linear molecules, the reaction heat is small, and a small amount of foaming gas is generated or vaporized. It exhibits a certain degree of fluidity, but it is not very significant; as the reaction continues, the exothermic heat further increases, and the vaporization of a large amount of blowing agent causes the rapid expansion of the foam (foaming period), which is caused by the expansion of the foam at this time. The flow fills most of the cavity; when the gel appears, that is,