Talking about cold sealant coating package

First, the origin and development of cold seal packaging technology in the flexible packaging industry Cold seal packaging technology first appeared in the UK in the early seventies in the flexible packaging industry, and its inspiration comes from the application of self-adhesive envelopes in the communications industry. At that time its packaging was chocolate. Its appearance overcame the most vexing problem in the packaging line of a chocolate factory. That is, once the packaging production line temporarily stops for some reason, the chocolate is deformed and melted due to the heat of the heat sealing strip on the heat sealing packaging machine, which not only causes inconvenience in production and a lot of consumption, but also causes the customer to complain and return a lot. The cold sealant packaging does not need to be heated in the sealing process, and a satisfactory sealing effect can be achieved only by exerting a certain pressure on the packaging film coated with the cold sealant. However, the cold sealant at that time was only a simple product without any improvement, and its use was very narrow. Therefore, its huge packaging potential and advantages have not been given full attention at the time.
After many years of development, cold seal packaging technology has made great progress and the scope of application has also rapidly expanded. In today's international market, packaging materials for cold sealant-coated packaging materials are no longer limited to chocolate, and have been expanded to include biscuits, ice cream, snacks, and confectionery, as well as packaging for first-aid items and sterilization tools in the pharmaceutical industry.
China's current packaging market, the use of cold sealant packaging is mainly chocolate packaging of several multinational companies, such as: the United States Mars Dove chocolate, the British Cadbury and Swiss Nestlé some chocolate packaging. However, with the full understanding of the advantages and characteristics of cold-sealed plastic packaging by domestic enterprises, with the progress of cold-sealing technology, there is great potential for the development of flexible packaging packaging materials for the flexible packaging industry.
Second, the advantages and characteristics of cold sealing plastic packaging materials 1. There is no thermal effect on the contents of the package, reducing waste in the packaging process and protecting the product. Because the packaging process using the cold sealant coating material is carried out in a "cold" state, it does not require that the packaging like the composite film needs to be sealed in a heated state, so that it is very good for heat sensitive articles such as chocolates and the like. Protection effect.
2. Can be used for materials that are not suitable for heat sealing. It does not cause shrinkage of the material due to heat. It can get a flat, beautiful seal shape, and because there is no heat effect, the contents can be tightly packed to make the packaging material and Content is kept at a minimum interval.
3. Faster packaging speed has greatly improved production efficiency. During the packaging process of the composite film, it is necessary to control three process parameters to obtain a satisfactory sealing strength, namely: heat sealing temperature, heat sealing time, and heat sealing pressure. For the cold seal packaging, only the sealing pressure can be controlled. The production speed change of the packaging production line has no effect on the sealing effect. Therefore, the sealing time can be greatly shortened, and the production speed can be increased by 50% to 100% compared with the heat sealing material.
4. Good cold resistance, at -20 °C, can also maintain the same sealing strength at room temperature.
5. It can reduce the maintenance cost of packaging equipment and reduce energy waste. And the operation of packaging equipment is safer.
6. Of course, the cold sealant packaging material also has limitations, its sealing strength is not large, generally only 2-4N/15mm, can only be used for light packaging; In addition, the product form can only be the shape of the film. Second, the composition of the cold sealant and some of the factors that affect its performance Cold sealant is a natural rubber as the main component of the glue, which added the right amount of acrylic copolymer, preservatives, defoamers, chemical stabilizers and other components .
1. The rubber component in the cold sealant provides adhesion between the cold sealants; and the synthetic resin provides the adhesion between the cold glue and the coated substrate.
2. In the cold sealant coating production, cold glue is applied to the corresponding substrate and a special adhesive layer is formed. The adhesive layer must meet three requirements: 1 The adhesive layer and the substrate have good Adhesion; 2 Adhesive layer has good adhesiveness with each other under cold pressure; 3 In the production process, back sticking does not occur after winding.
3. The cold sealant should prevent contamination during the production process, otherwise it will cause the rubber component in the cold sealant to soften and cause the cold sealant to be scrapped. The main sources of pollution are two: 1 organic solvents; 2 copper materials and cold sealant contact.
4. The coating amount of the cold sealant is directly proportional to its sealing ability. Generally, the gel amount of the cold sealant is 3-4.5g/m2.
5. Back-adhesion is the most common problem in the production of cold sealants. The measure taken is to apply a layer of release agent on the other side of the substrate. In addition, excessive winding tension is one of the reasons for the back-adhesion of the cold sealant. Secondly, the cold sealant does not dry well, and the cold sealant is contaminated. The packaging film roll is locally compressed and the ambient temperature is also the cause of back sticking.
Fourth, cold sealing plastic packaging materials production process The production of cold seal packaging uses gravure coating. In actual production, the front side of the substrate is coated with a release agent after the pattern is printed, and the back side of the substrate is coated with a certain shape of a cold sealant and closely corresponds to the front side pattern. The registration accuracy of general cold sealant coating is ≤±2mm, and the adhesive tape used in the finished joint must have no adhesion to the cold sealant.
2. The cold sealant is applied to the opposite side of the substrate, and the gluing unit needs a reversal device to achieve this function. There are two general coating methods for cold sealants. One is the line coating on the printing machine, that is, the substrate is printed on the surface of a surface, ten coating stripping agents are reversed, and the cold sealing glue is coated and wound up; The method is to apply a cold sealant to the printed substrate after composite processing, ie, the substrate is printed->composite->coating stripper->reverse->cold sealer. Under normal circumstances, the former process is easy to operate, and the cold seal adhesive is easy to register. Due to factors such as dimensional changes after the material is compounded, the color of the cold seal adhesive is relatively difficult.
3. Since the cold sealant is a water-soluble binder, and the volatilization rate of water is much lower than that of organic solvents, the drying ability of the cold sealant unit drying system is greater than that of other units.
4. The rolled up film must be hung on the shelf and should not be placed on the ground or on the shovel. It should not be stacked vertically to prevent back sticking. The finished product roll should be wrapped with black PE or aluminized film to avoid Light dustproof purpose.
In short, the production of cold sealant coating is a high-tech and difficult production process, which fully reflects the manufacturer's technical capabilities, quality control capabilities, and management capabilities.