"If there are small bubbles in the complex, opaque and foggy, it will not only affect the appearance quality, but also affect the peeling strength of the complex, reducing it, which is a very bad phenomenon." 1.The surface tension of the base film is too small, the infiltration is poor, the glue is not uniform, and the space without glue is empty and bubbles are generated. The solution is to use a film with a surface tension greater than 38mN/m, or re-corona treatment, or online corona treatment, qualified for reuse. 2.The pressure of the composite roller is insufficient, or the surface temperature of the composite steel roller is too low, the activation of the adhesive is insufficient, the fluidity is insufficient, the micelles of the same dot are uneven, and there are small gaps, resulting in very small bubbles. At this time, the surface temperature of the composite steel roller should be increased, and the pressure should be increased. It is best to smooth the rubber particles with an inverted rubber roller before applying the adhesive base film into the baking channel. 3.The Angle between the composite roll and the film is not appropriate, the envelope Angle is too large, especially for rigid materials, easy to cause folds and even bubbles. The Angle should be carefully adjusted, the wrapping Angle should be changed, and the composite roller should be entered as far as possible according to the tangential direction. 4.There is dust attached to the surface of the film, the dust particles will be two layers of film up, forming a circle around the empty ring is a little bit of air bubble, look carefully in the middle of a black spot. If there is such a phenomenon, should pay attention to the environment clean, keep the air fresh. 5.There is a trace of water mixed in the adhesive, and an NCO in the adhesive reacts with water to produce CO2 gas. Therefore, it is necessary to keep dry on solvents and environmental humidity to eliminate the cause of CO2 production. 6, residual solvent, and the permeability of the solvent is poor, the solvent gasification to form bubbles sandwiched between the two layers of film. Therefore, the amount of residual solvent should be controlled, or the base film with a large solvent transmittance should be decompounded. Sinograce Chemical has high quality water-based acrylic film adhesive, welcome to consult and buy

Considering from two aspects of packaging cost and performance requirements, the thickness selection of each layer of composite flexible packaging materials should be carefully weighed. In general, the heat seal layer can be determined by market generalization and standardization, the strength support layer is generally determined according to the weight of the packaged product, and the thickness of the functional material is generally determined by the shelf life of the product. 1.Permeability coefficient: According to the maximum allowable water absorption of the packaged product or the maximum allowable water removal of the product, the method is mainly suitable for the design of moisture-proof packaging products, and the key is to calculate the moisture permeability coefficient of flexible packaging composite materials. 2.Oxygen permeability coefficient: According to the maximum allowable oxygen absorption of the packaged product, the method is mainly suitable for the product barrier packaging which is very sensitive to oxygen, and the key is to calculate the oxygen permeability coefficient of the flexible packaging composite material. 3.Number of microorganisms: According to the maximum allowable number of microorganisms per unit volume or unit surface area, the method is mainly suitable for mildew resistant packaging of products that are very sensitive to microorganisms, and the key is to determine the type of microbial products and the law of reproduction and growth. 4.oxygen coefficient and carbon dioxide coefficient: According to the maximum amount of carbon dioxide or oxygen permeability allowed by the packaging container, the method is mainly for the inflatable insurance packaging of products, products with declared activity need oxygen insurance or maintain bright color, but also need high concentration of carbon dioxide to inhibit the growth and reproduction of microorganisms, the key is to calculate the oxygen permeability coefficient and carbon dioxide permeability coefficient of flexible packaging composite materials. When packaging products, sometimes it is necessary to achieve the purpose of moisture-proof packaging, but also to achieve the purpose of oxygen resistance packaging or mildew proof packaging. Therefore, the thickness of the composite packaging material is generally determined by the main packaging purpose of the product packaging and the shelf life of the product, and then the theoretical shelf life of the designed packaging is estimated according to the thickness of the material and another packaging purpose to verify the rationality of the design of the packaging.

The transparency of composite film is very high, but in the composite processing of plastic film, the composite film often has problems such as insufficient transparency. So, what is the reason for affecting the transparency of the composite film? This article analyzes one by one for reference. Improper selection of adhesives: Such as the color of the adhesive itself is dark or the fluidity is insufficient, the leveling performance is poor, and it cannot be fully spread on the composite base film. Generally, the higher the solid content of the main glue, the better the fluidity, which is conducive to spreading on the film. In general, 75% of the glue is better than 50% of the transparent effect, 50% of the glue is better than 40% or 35% of the glue. For compliant films with high transparency requirements, the use of 50% and 40% adhesive composite is difficult to meet the requirements. Process problems: First of all, the drying temperature of the drying channel of the composite machine is too high, and the solvent on the surface of the adhesive liquid is quickly dispersed (steam), and the adhesive liquid is crusts on the surface prematurely. Then, when the heat goes deep into the inside of the adhesive liquid layer, the solvent under the adhesive film will vaporize. When the gas breaks through the epidermal adhesive film to form a ring like a volcanic vent, which also makes the adhesive layer not transparent enough. Secondly, if the conforming roller or scraper is defective, a certain point is not compacted, forming a neutral, which will also cause the compliant film to be opaque. There is too much dust in the air added to the working environment, and there is also dust in the hot air sucked into the drying channel after gluing, which is stuck on the surface of the adhesive layer or sandwiched between the two layers of the base film when composite, and a lot of dust causes opacity or poor transparency. The solution is to close the glue part of the composite machine, and use a high mesh filter on the air inlet of the baking channel to block the suction of dust (that is, the dust in the hot air of the baking channel). In addition, if there is no roll or the roll is not clean, it will make the composite film not transparent enough, or the amount of composite glue is insufficient, the glue is uneven and there is a blank, and there are small bubbles, resulting in speckles or opacity. The solution is to check and adjust the amount of glue so that it is sufficient and evenly coated, resulting in the common name of "pockmarked face film". Other problems It should be noted that the composite hot drum temperature is not enough, the hot melt part of the glue fails to melt, the cooling roller temperature is too high, and the failure to cool suddenly can cause poor transparency of the compliant film. Solution: The temperature of the hot drum shall not be lower than 70 degrees, and the hot melt part of the colloid begins to melt when the temperature reaches 65 ...

The performance requirements of water-based varnish for printing paper glazing are as follows: 1.The film has good environmental resistance. Some of the printed matter after glazing is used to make all kinds of packaging cartons, in order to be able to play a good protective effect on the packaged products, the environmental resistance of the glazing film layer must be better. For example, the packaging of food, cigarettes, cosmetics, clothing and other goods must have moisture-proof and mildew proof performance. After drying, the chemical resistance of the film layer should be stable, and its properties can not be changed by contact with chemical substances such as weak acids or weak bases in the environment 2.High transparency of the film layer, no discoloration. Prints to obtain excellent glazing effect, depends on the surface of the printed sheet to form a colorless transparent film, and after drying the text does not change color. It should not be discolored or yellowed due to sun exposure or long use time. 3.The film layer has a certain wear resistance. Printed paper requires a certain wear resistance and scratch resistance after glazing. 4.Good leveling, smooth film surface. There are many kinds of printing materials to print the impact of graphics, surface absorption, smoothness, wettability and so on are very different, in order to make the coating on the surface of different products can form a smooth film layer, requiring water-based polish smooth, smooth film surface. 5.With a certain flexibility. The bright film formed by any kind of water-based gloss oil on the surface of the printed matter must maintain good elasticity to adapt to the flexibility of paper or cardboard, and will not be damaged or cracked and fall off. 6. It has a certain adhesive force on the surface of printed matter. Due to the influence of the integral density of the ink layer on the surface of the printed matter, the surface adhesive suitability is greatly reduced. In order to prevent the film layer from dry cracking and defilm in use after drying, it is required that the film layer has strong adhesive force, and has certain adhesive force for ink and various auxiliary materials used in ink mixing.