The migration of the hottest aluminum coating and

The migration of aluminum coating and film additives

composite flexible packaging materials have developed rapidly in recent years. Because of its advantages of variety diversification and comprehensive performance, it is more and more widely used in food, medicine, daily chemical industry and other fields. The involved substrates also cover a wide range of paper, aluminum foil and various plastic films. This paper briefly discusses the problems in the use of aluminum plating film and polyethylene film (CPE)

the research and development, production and utilization of biodegradable plastics are of great significance to the sustainable development of the plastic industry. 1. The migration of aluminized layer

aluminized film is a new material that has appeared in recent years. It not only has the characteristics of plastic film, but also replaces aluminum foil to some extent, plays a role in improving the grade of products, and the cost is relatively low. Therefore, it is widely used in the packaging of biscuits and snack foods. However, in the production process, the transfer of aluminum coating often occurs, which leads to the reduction of the peel strength of the composite film, the decline of product performance, and even seriously affects the quality of the packaging contents

at present, there are two kinds of aluminum plating films: CPP aluminum plating film and pet aluminum plating film. The corresponding composite film structures include opp/cpp aluminum plating, pet/cpp aluminum plating, pet/pet aluminum and so on. In practical applications, the most likely problem is PET composite pet aluminizing. The main reason is that as the base material of aluminum plating, CPP and pet have great differences in tensile properties. Pet has great rigidity. Once it is compounded with the same material with great rigidity, it is easy to cause the destruction of the adhesion of the aluminum plating layer due to the existence of cohesion in the curing process of the adhesive film, so that the aluminum plating layer migrates. In addition, the penetration of the glue itself also has a certain impact on it. In this regard, in the operation of the composite process, the following aspects should be paid attention to:

(1) select the appropriate adhesive. In the composite aluminum plating film, pay attention not to use the adhesive with too low viscosity, because the low viscosity adhesive has small molecular weight and weak intermolecular force, so the molecular activity is relatively strong, which is easy to destroy the strength of its attachment to the substrate through the aluminum plating layer of the film

(2) enhance the softness of the adhesive film. The specific method is to reduce the amount of curing agent when preparing the working adhesive, so that the degree of cross-linking reaction between the main agent and the curing agent is reduced, so as to reduce the brittleness of the adhesive film, maintain good flexibility and extensibility, and help to control the transfer of aluminum coating

(3) the amount of glue should be appropriate. If the amount of glue is too small, it will undoubtedly cause smaller composite fastness and easy peeling; However, it is not good to apply too much glue. First, it is uneconomical. Second, the large amount of glue applied and the long curing time have a strong penetration effect on the aluminum coating. Therefore, a reasonable amount of glue should be selected

(4) control the tension. During aluminum plating unwinding, the tension must be well controlled, so that graphene has many unique physical and chemical properties that are too large. The reason is that the aluminized film will stretch under tension, resulting in elastic deformation. Its aluminum coating is correspondingly easy to loosen, and the force of attaching new materials is relatively reduced

(5) ripening speed. In principle, the curing temperature should be increased and the curing speed should be accelerated, so that the adhesive molecules can solidify quickly and reduce the penetration damage

2. The precipitation of additives in CPE film

the additives mentioned here mainly refer to the lubricants used in the production of CPE film, especially the external lubricants. Most of them are some low melting point waxes, which are easy to precipitate to the surface of the film. Practice shows that when the thickness of CPE film exceeds 60, the phenomenon of additive precipitation will greatly increase, because under the same specific surface area, with the increase of film thickness, the amount of additives contained in the film is also increasing, so the possibility of precipitation also increases. What effect does the precipitation of Wu additive have on the composite film? The most important thing is that it will produce a barrier layer, which greatly weakens the composite strength. Especially in the edge banding position, it is easy for weapons and delamination. Some manufacturers often encounter such problems when producing vacuum bags and rice packaging bags. To solve the problem of additive precipitation, there are the following points in the process:

(1) film surface treatment. In addition to the film manufacturer's own control, users must confirm that the surface tension of CPE film fully meets the requirements when using it. If necessary, it is even necessary to conduct electric spark treatment again, because the wax precipitated can be volatilized and removed under the high temperature of electric spark

(2) select appropriate adhesive. From the perspective of adhesives, it is necessary to enhance the inclusiveness of glue to additive precipitates and minimize its impact

(3) maturation control. Different from aluminizing film, here, we should try to ripen at low temperature to avoid high temperature intensifying precipitation. The migration of aluminum coating and film additives

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composite flexible packaging materials have developed rapidly in recent years. Because of its advantages of variety diversification and comprehensive performance, it is more and more widely used in food, medicine, daily chemical industry and other fields, and the substrates involved also cover a large range, including paper, aluminum foil and various plastic films. This paper briefly discusses the problems in the use of aluminum plating film and polyethylene film (CPE)

1. Migration of aluminized layer

aluminized film is a new material emerging in recent years. It not only has the characteristics of plastic film, but also replaces aluminum foil to some extent, playing the role of improving product grade, and relatively speaking, the cost is low. Therefore, it is widely used in the packaging of biscuits and snack foods. However, in the production process, the transfer of aluminum coating often occurs, which leads to the reduction of the peel strength of the composite film, the decline of product performance, and even seriously affects the quality of the packaging contents

at present, there are two kinds of aluminum plating films: CPP aluminum plating film and pet aluminum plating film. The corresponding composite film structures include opp/cpp aluminum plating, pet/cpp aluminum plating, pet/pet aluminum and so on. In practical applications, the most likely problem is PET composite pet aluminizing. The main reason is that as the base material of aluminum plating, CPP and pet have great differences in tensile properties. Pet has great rigidity. Once it is compounded with the same material with great rigidity, it is easy to cause the destruction of the adhesion of the aluminum plating layer due to the existence of cohesion in the curing process of the adhesive film, so that the aluminum plating layer migrates. In addition, the penetration of the glue itself also has a certain impact on it. In this regard, in the operation of the composite process, the following aspects should be paid attention to:

(1) select the appropriate adhesive. In the composite aluminum plating film, pay attention not to use the adhesive with too low viscosity, because the low viscosity adhesive has small molecular weight and weak intermolecular force, so the molecular activity is relatively strong, which is easy to destroy the strength of its attachment to the substrate through the aluminum plating layer of the film

(2) enhance the softness of the adhesive film. The specific method is to reduce the amount of curing agent when preparing the working adhesive, so that the degree of cross-linking reaction between the main agent and the curing agent is reduced, so as to reduce the brittleness of the adhesive film, maintain good flexibility and extensibility, and help to control the transfer of aluminum coating

(3) the amount of glue should be appropriate. If the amount of glue is too small, it will undoubtedly cause smaller composite fastness and easy peeling; However, it is not good to apply too much glue. First, it is uneconomical. Second, the large amount of glue applied and the long curing time have a strong penetration effect on the aluminum coating. Therefore, a reasonable amount of glue should be selected

(4) control the tension. During aluminum plating unwinding, the tension must be well controlled and not too large. The reason is that the aluminized film will stretch under tension, resulting in elastic deformation. The aluminum coating is correspondingly easy to loosen, and the adhesion is relatively reduced

(5) ripening speed. In principle, the curing temperature should be increased and the curing speed should be accelerated, so that the adhesive molecules can solidify quickly and reduce the penetration damage

2. The precipitation of additives in CPE film

the additives mentioned here mainly refer to the lubricants used in the production of CPE film, especially the external lubricants. Most of them are some low melting point waxes, which are easy to precipitate to the surface of the film. Practice shows that when the thickness of CPE film exceeds 60, the phenomenon of additive precipitation will greatly increase, because under the same specific surface area, with the increase of film thickness, the amount of additives contained in the film is also increasing, so the possibility of precipitation also increases. What effect does the precipitation of Wu additive have on the composite film? The most important thing is that it will produce 7 Ensure that the connection of each connecting line is correct and reliable, and create a barrier layer, which greatly weakens the composite strength, especially in the edge banding position, which is easy to separate weapons and layers. Some manufacturers often encounter such problems when producing vacuum bags and rice packaging bags. To solve the problem of additive precipitation, there are the following points in the process:

(1) film surface treatment. In addition to the film manufacturer's own control, users must confirm that the surface tension of CPE film fully meets the requirements when using it. If necessary, it is even necessary to conduct electric spark treatment again, because the wax precipitated can be volatilized and removed under the high temperature of electric spark

(2) select appropriate adhesive. From the perspective of adhesives, it is necessary to enhance the inclusiveness of glue to additive precipitates and minimize its impact

(3) maturation control. Different from aluminizing film, here, we should try to ripen at low temperature to avoid high temperature intensifying precipitation