一、热封温度

Heat sealing temperature

复合膜的热封温度的选择与复合基材的性能、厚度，制袋机的型号、速度、热封压力等有密切关系，直接影响热封强度的高低。

The selection of heat sealing temperature of composite film is closely related to the properties and thickness of composite substrate, the type, speed and heat sealing pressure of bag making machine, and directly affects the strength of heat sealing.

复合膜的起封温度是热封材料的粘流温度Tf（或熔融温度Tm）决定，热封的最高温度不能超过热封材料的分解温度Ta。Tf（Tm）～Ta之间的温度范围即为热封材料的热封温度范围。它是影响热封质量控制的关键因素，热封温度范围越宽，热封性能越好，质量控制越容易，越稳定。

The sealing temperature of the composite film is determined by the viscosity flow temperature Tf (or melting temperature Tm) of the heat sealing material, and the maximum temperature of the heat sealing can not exceed the decomposition temperature of the heat sealing material Ta. The temperature range between Tf (Tm) to Ta is the heat sealing temperature range of heat sealing material. It is the key factor affecting the quality control of heat sealing. The wider the heat sealing temperature range is, the better the heat sealing performance is. The easier the quality control is, the more stable the quality is.

同时复合薄膜的热封温度不能高于印刷材料的热定型温度以上。否则会引起热封部位的收缩、起皱，降低了热封强度和袋子的抗冲击性能。印刷材料的耐热性好，如PET、ONY等，在生产中可以提高热封温度以快速生产；印刷材料的耐温性差，如BOPP，则尽量采用采用较低的热封温度，而通过增加压力，降低车速或选择低温热封材料来保证热封强度。

At the same time, the heat sealing temperature of the composite film can not be higher than the heat setting temperature of the printing material. Otherwise, the shrinkage and wrinkling of the heat sealing zone will be caused, and the heat sealing strength and the impact resistance of the bag will be reduced. Heat resistance printing materials, such as PET, ONY, in the production process can improve the heat sealing temperature to the rapid production of printed material; temperature difference, such as BOPP, is as far as possible the use of heat sealing temperature is low, and by increasing the pressure, reduce the speed or low temperature heat sealing materials to ensure the heat sealing strength.

热封温度的设定应在热封材料的热封温度范围内，一般在粘流温度Tf（或熔融温度Tm）上15℃～30℃（如果在这个范围内，不能使热封层真正封合，必须从压力、速度、机械性能上去设法改善，压力并非越大越好，太大也会损伤焊边，造成断根问题。“补充探讨”），热封温度过高，易使热封部位的热封材料熔融挤出，降低了热封厚度，增加了焊边的厚度和不均匀。虽然表观热封强度强度较高，却会引起断根破坏现象，大大降低封口的耐冲击性能（容易产生破袋的问题，“补充”），密封性能。（这个分析很有道理。）热封温度低于热封材料的软化点，加大压力和延长热封时间均不能使热封层真正封合。

Heat sealing temperature should be set in the heat sealing temperature range of heat sealing material, usually in the viscous flow temperature Tf (or melting temperature Tm) of 15 to 30 DEG C (if in this range, can not make the real heat sealing sealing, must from mechanical pressure, speed, pressure to try to improve. Not better, too much will damage the weld edge, caused by the root problem. The heat sealing temperature is too high to melt and extrude the heat sealing material in the heat sealing part, which reduces the thickness of the heat seal and increases the thickness and unevenness of the welding edge. Although the strength of the apparent heat sealing strength is higher, it will cause the phenomenon of root cutting, greatly reduce the impact resistance of the sealing (easy to break the bag problem, "supplement"), sealing performance. (this analysis makes sense.) The heat sealing temperature is lower than the softening point of the heat sealing material, increasing the pressure and prolonging the heat sealing time can not really seal the heat sealing layer.

连续自动灌装设备的热封温度设定往往较高，因为在热封时，易受到内装物的污染、挤压、冷却速度的影响。

The sealing temperature setting of continuous automatic filling equipment is often higher, because it is easy to be affected by contamination, extrusion and cooling rate when the heat seal is used.

二、热封压力

Two. Heat sealing pressure

在热封温度下，热封材料开始熔化，在粘接面上施以压力，使对应的热封材料相互接触、渗透、扩散，也促使薄膜表面的气体逸出，使热封材料表面的分子间距离缩小，产生更大的分子间作用力，从而提高了热封强度。（再补充热封理论）

In the heat sealing temperature, heat sealing materials began to melt, pressure on the bonding surface, the heat sealing material corresponding to the contact, infiltration, diffusion, also causes the gas to escape from the film surface, to narrow the distance between the surface of the molecular heat sealing material, produce greater molecular interactions, thus improving the heat sealing strength. (supplementary heat sealing theory)

热封压力由制袋机上的弹簧提供。对于轻薄包装袋，热封压力至少在1。96N/㎝²以上。热封压力的大小与复合膜的结构性能、厚度、热封宽度等有关。

The heat sealing pressure is provided by the spring on the bag making machine. For light packaging bags, the heat sealing pressure is at least 1. 96N/ - cm above. The heat sealing pressure is related to the structure performance, thickness and heat sealing width of the composite membrane.

热封材料有较高的活化能，升温对其粘度的下降影响较大，所需的热封压力较小，以免热封部位的熔融材料被挤出，降低了热封效果。而PE、PP为非极性热封材料，活化能极小，所需压力较高，对热封强度，界面热封性有利。（这段如何理解，应该是热封材料中有较高活化能的热封材料和较低活化能的热封材料，PE、PP是常用的热封材料，这里所指应是普通型号的PE、PP材料，是属于活化能较小的热封材料，而与之共聚、共混改性，或特殊催化、离子型树脂等热封材料，如mPE、EVA、EAA、EMAA、Surlyn等是属于活化能较镐的热封材料。不知这样理解对吗？）

The heat sealing material has higher activation energy, and the effect of temperature rising on its viscosity decreases greatly, and the required heat sealing pressure is smaller, so as to avoid the extrusion of the melted material in the heat sealing part and reduce the heat sealing effect. While PE and PP are non polar heat sealing materials. The activation energy is very small and the required pressure is higher, which is beneficial to the heat sealing strength and the interfacial heat sealing property. (this should be how to understand, heat sealing material has higher activation energy of heat sealing material and lower the activation energy of the heat sealing materials, PE, PP is a commonly used heat sealing material, referred to here should be the common types of PE and PP materials, belongs to the low activation energy of heat sealing materials, and with a total of poly, blending modification, or special catalysis, ion type resin sealing materials, such as mPE, EVA, EAA, EMAA and Surlyn belong to the activation energy than pick heat sealing material. I don't know that, right?

热封压力随着复合膜的厚度增加而增加，若热封压力不足，热封丙层薄膜难以热合，难以排尽夹在焊缝中间的气泡；热封压力过高，会挤走熔融材料，损伤焊边，引起断根。计算热封压力时，要考虑所需热封棒的宽度（是指热封宽度而不是指棒的整个宽度）和实际表面积（是指热封接触面积）。热封棒宽度越宽，所需的压力越大。热封棒的宽度过宽，易使热封部位夹带气泡，难以热封牢固。一般采用镂空的热封棒，在最后一封加强热封牢度。相同宽度（热封宽度）的热封棒，若表面刻纹，其实际接触面积大大减小，单位面积压力相应增大。这对热封宽度较大的包装袋是有益的。

Heat sealing pressure increases with the thickness of the film increases, if insufficient heat sealing pressure, heat sealing layer to heat C, it is difficult to exhaust clamp in the middle of weld bubble; heat sealing pressure is too high, will crowd out the molten material, welding edge damage, caused by root pruning. When calculating the heat sealing pressure, the width of the required heat sealing rod (i.e. the width of the heat seal, not the whole width of the rod) and the actual surface area (i.e. the heat sealing contact area) should be considered. The wider the width of the heat seal, the greater the pressure required. The width of the heat sealing rod is too wide, so that the heat sealing part is easy to be filled with bubbles, and it is difficult to seal the heat firmly. A hollow heat sealing rod is usually used to strengthen the heat sealing fastness of the last one. If the surface of the heat sealing rod with the same width (heat sealing width) is etched, the actual contact area will be greatly reduced, and the pressure per unit area will increase accordingly. This is useful for packaging bags with larger heat sealing widths.