Study on Quality Improvement Techniques for Injection-Molding of Polymer Utilizing Heat Transfer Control

在本研究中，研究了聚合物材料的辐射加热作为模内冷却的主动控制技术。为了阻止注射到冷模腔内的聚合物熔体冷却，在注射成型过程的填充阶段，利用CO2激光对腔内的聚合物熔体进行加热，并实验研究了辐射加热对成型聚合物质量的影响。结果总结如下：(1)辐射加热提高质量：采用辐射加热技术生产聚苯乙烯带材，并对成型聚合物的质量进行了研究。由于辐射加热对冷却的阻碍，减少了填充阶段聚合物熔体凝固产生的故障，如模塑带材表面残留的双折射冻结、聚合物熔体粘度增加导致的短射、带材表面可转录性降低等。(2)红外激光辐照聚合物的温度分布：红外辐射照射下聚合物熔体内的温度分布由聚合物内的辐射吸收与由于与冷模壁接触而产生的导电冷却之间的关系决定。为了了解辐照条件下聚合物的温度分布，对聚合物内部的传热进行了数值模拟。结果表明：聚合物材料的单色吸收系数与加热红外辐射的波长分布之间的关系对模制聚合物内部的温度有强烈的影响，在实际条件下，红外辐射的加热效应从聚合物表面穿透0.5 ~ 1mm左右。

In this study, radiation heating of the polymeric materials was investigated as the active controlling technique for cooling of moldedpolymer within the mold. In order to obstruct the cooling of polymer melt injected into the cold mold cavity, polymer melt in the cavity was heated by using CO2 laser during the filling stage of the injection-molding process, and the effects of radiation heating on the quality of molded polymer was experimentally examined. The results can be summarized as follows :(1) Quality Improvement due to Radiation Heating : Radiation heating technique was adoptedto produce a polystirene strip, and the quality of molded polymer was investigated. The obstruction of cooling due to radiation heating results in reducing the failures originated from solidification of polymer melt during the filling stage, such as residual birefringence frozen in surface region of molded strip, short-shot due to increasing the viscosity of polymer melt, lowering the transcribability of strip surface, etc.(2) Temperature Profiles in the Polymer Irradiatedby InfraredLaser : Temperatureprofile within the polymer melt irradiatedby infraredradiation is determinedby the relation between radiation absorption within the polymer and conductive cooling due to contact with the cold mold wall. In order to obtain the understandings about the temperature profiles under the irradiation condition, heat transfer within the polymer was numerically examined. The results showed that the temperature within the molded polymer is strongly affected by the relation between the monochromatic absorption coefficient of polymer material and wavelength distribution of the heating infraredradiation, and that, under the realistic condition, heating effect due to infraredradiation penetrates about 0.5-1mm from the polymer surface.