High-temperature cooking bag production requirements for the amount of glue

At present, there are more and more enterprises producing high-temperature retort pouches, and quite a few companies have mastered the relatively mature production process of high-temperature retort pouches, but in the production process of high-temperature retort products, the amount of glue is generally required to reach 4g/m2 or more. The curing time is often more than 72h. On the one hand, the amount of glue increases the production cost. On the other hand, the long curing time means that the product has a long production cycle, which is not conducive to the flow of materials, and cannot meet the short-term demand of customers. This is a big problem for many companies. This article will focus on the requirements of the use of high-temperature retort pouches on the amount of sizing and make a preliminary vision for the future development of high-temperature retort pouch production.

First, the definition of the amount of glue

The amount of sizing is how many masses of dry-based adhesive per square meter of substrate, generally expressed in g/m2.

Second, the relationship between the amount of glue and the composite strength

The general theory of the amount of sizing and the strength of the composite is that the composite strength increases with the increase of the amount of sizing, but after the sizing amount reaches a certain level, the corresponding composite strength increases relatively slowly, tending to a balance; Continue to increase the situation due to factors such as curing time, equipment drying capacity, material structure and other factors may even decrease. The general relationship between the amount of glue applied and the composite strength is shown in the figure:

Third, the reaction of the high temperature cooking bag during the cooking process requires the amount of glue

The high temperature cooking bag is generally sterilized by placing it in hot water at 121 ° C or 135 ° C together with the food. During the high temperature cooking process, the substrate will shrink to different degrees. If the composite strength of the high temperature cooking bag is low, the composite bag layer is interposed. There is not enough force to prevent the substrate from shrinking, which causes the bag to have a relatively serious separation phenomenon after high-temperature cooking. From the general relationship between the amount of glue applied and the composite strength, it can be known that only the amount of glue reaches a certain amount, so that the composite strength can be obtained. Achieve a higher level, keep the high temperature cooking bag from delamination and wrinkle during the cooking process; in addition, since the glue used in the high temperature cooking bag is generally of the two-component polyurethane resin type, the polyurethane resin itself has a certain hydrophilicity. The amino group and the ester group in the resin have extremely strong polarity, and are easily hydrolyzed under the moist heat conditions, and the hydrogen bond between the polyurethane resin and the surface of the substrate is easily damaged, thereby lowering the bonding strength and even Adhesive layer peeling will occur, so only the amount of glue is ensured to ensure that the main agent and curing agent of the high temperature cooking glue are sufficiently crosslinked during the ripening process to generate high scores.

Fourth, the high temperature cooking bag printing process requires the amount of glue

Under normal circumstances, the packaging needs to have a beautiful printed pattern as a decoration, as well as a high-temperature retort pouch. The surface of the printed film has poor flatness, and only a relatively large amount of sizing can fill the surface of the gap, As for the production of a large number of white spots; in addition, the printing surface of the printing ink is relatively rough after the printing, the amount of ink can generally reach 2 ~ 3g / m2, the ink layer will absorb a part of the glue in the composite process, resulting in insufficient glue on the surface of the composite layer, thus Packaging for high-temperature cooking purposes requires a higher amount of sizing to ensure product performance.

V. Requirements for the amount of glue applied to the high temperature cooking bag compounding process

The depth of the composite coating mesh for the production of high-temperature cooking products is generally required to be >=90um, so as to effectively ensure that the amount of glue applied to the product reaches 4g/m2 or more. Under normal circumstances, the amount of glue applied to the plate can meet the requirements. After using it for a while, the amount of glue will decrease. In this respect, the depth of the net roller and the scraper is reduced, and on the other hand, the mesh roll for the high-temperature cooking product is mostly corrosive and pyramidal, and the glue is easily deposited inside the dot, even if it is just The used version is immediately placed on the plate washer for rolling cleaning, or the plate cleaning solution used for a period of time is deeply cleaned, which can not effectively ensure that the rubber roller can be thoroughly cleaned, thus causing each dot to correspond The sizing area cannot effectively ensure that the amount of sizing is within the standard range, so that there are tiny bubbles or defects between the glue layer and the film. A tiny bubble or rubber layer defect is an internal stress failure point that directly affects the composite strength of the product. The amount of glue on the high-temperature cooking products reaches a certain level, which can effectively reduce the defects in the micro-bubbles or the rubber layer caused by poor wetting between the glue layer and the film, even if there are dots with insufficient glue amount, but because The overall amount of glue is high, and the nearby area can effectively supplement the performance to ensure the overall quality of the product.

Sixth, production examples

In the actual composite production process, due to the influence of printing ink thickness, composite coating roller line number, composite pressure, adhesive working concentration, composite substrate and other factors, the amount of glue may not reach or exceed 4g/m2. If the amount of glue is too low, the composite strength can not meet the requirements, which will greatly increase the risk of separation and wrinkling of the retort pouch during the cooking process; if the amount of sizing is high, the product performance may meet the requirements for use, but it will increase the production cost. . Under normal circumstances, the amount of sizing of high temperature cooking products is controlled within the range of 3.8 to 4.5 g/m2. In order to ensure that the amount of sizing of high-temperature cooking products can meet the requirements, in addition to the appropriate working concentration of the glue, before the start-up, it is necessary to test the amount of sizing of the product under normal production process conditions, and to formulate appropriate process parameters. It is necessary to pay attention to the cleaning and treatment of the rubberized mesh roller to ensure that there is not too much residual glue to block the mesh roller and ensure the coating ability of the mesh roller.

The following is an example of the production of a high temperature cooking bag:

Product structure: PET12/NY15/RCPP70 (PET full printing)

Product use: baby rice noodles

Cooking conditions: 121 ° C, 30 min

Equipment: Beiren Machinery

Adhesive: Adhesive is YH3166 (high temperature cooking glue), YH3166: YH3166B: EA=10:1.5:14.3, working concentration 30%

Process parameters: 120um 90L mesh roll, gluing amount 3.95g/m2, coating pressure 0.32MPa, scraper pressure 0.2MPa, compound pressure 0.5MPa, oven temperature 70°C°C, 80°C, 90°C, compound temperature 65°C, machine The speed is 110m/min, the curing temperature is 52°C, and the curing time is 96h.

Conclusion:

It can be seen that both the printing process of the high-temperature cooking product, the composite process, and the special use conditions of the high-temperature cooking product require that the sizing amount of the high-temperature cooking product reaches 4g/m2 to ensure that the product has good composite strength and temperature resistance. Sex, water resistance, and reducing the amount of glue will increase the quality risk of high temperature cooking products to a certain extent.