There are relatively few composite membrane manufacturers using solvent-free composite production for cooking products . Although many manufacturers can meet the requirements after testing, the stability and risk of mass production are still to be discussed.
Differentiated by cooking temperature, the current solvent-free cooking process is mainly suitable for 121 ℃ cooking composite packaging bags , 135 ℃ cooking products are rarely used, this is mainly because the solvent-free adhesives and solvent-free processes are not very mature, yet The adhesive needs to be further improved and perfected. Even for 121 ℃ transparent cooking products, if they are not properly controlled during the production operation, abnormal phenomena such as broken bags and delamination will occur after cooking. In general, we can strengthen the management and control in terms of materials, temperature and humidity, the amount of glue, winding and curing.
1. The material thickness deviation should be small
Because the amount of solventless compound is very small, only 1/2 ~ 1/3 of dry compound , that is, about 2g / ㎡, so the thickness deviation of each layer of material is required to be very small, especially the thickness control of the inner layer material RCPP . Generally speaking, solvent-free compound cooking products, the inner layer material will be more than 50um , and the amount of glue is only about 1.5 ~ 2.5um thickness. If the thickness deviation of the material is large, it will cause the solvent-free adhesives to flow in the roll film after the composite semi-finished product is wound, which will cause the glue amount of the thin material position to become larger and the material thick position to become smaller. This is because the position of the thick material is larger than the position of the thin material. The internal stress is larger, which will cause the glue to flow from the thick material to the thinner material. .
2. The influence of temperature and humidity on curing
The curing process of the solventless adhesive is actually the reaction process of the NCO group of the solventless main agent and the OH group of the curing agent at a certain temperature and humidity, so the completeness of the reaction of the solventless adhesive is affected by the main agent curing agent The proportion and humidity affect, and the high-temperature cooking product has a larger amount of glue than ordinary products, so the proportion of main agent curing agent and humidity have a greater impact on the curing of the adhesive. Therefore, in actual production, the proportion of the main agent curing agent should be adjusted according to different seasons in different regions.
3. Balancing quantity and winding system
As we all know, one drawback of the solvent-free compound process is that after the compound semi-finished product is off the machine, the glue has no initial tack and still has fluidity. Therefore, the solvent-free process requires very high equipment rewinding systems. If the winding system of the machine is not good, the glue will flow out to the end surface after getting off the machine, the winding will be uneven, and the bottom of the roll will be wrinkled.
Solvent-free cooking process due to the subsequent processability of the finished product determines the gumming amount of the cooking product is 25% ~ 40% higher than that of ordinary products, so it is more prone to glue outflow than ordinary products.
In addition to the solvent-free winding system, the uniformity of the amount of glue applied in the vertical and horizontal directions is also very important when the solvent-free compound is used. The amount of local glue in the finished product is too small, which affects the cooking performance of the finished product.
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