The analysis of the causes of low transparency dry type composite membrane and countermeasures

Dry compound process is one of the common way. Process flow is: face film paper & rarr; Sunken eye roll coating & rarr; Bake, heat drying & rarr; Composite rolling stick composite & rarr; The finished product winding & rarr; Maturation of finished product. Due to the flexible packaging industry competition is intense, the customer's requirements more and more is also high. This is particularly true of requires high transparent packaging. In this paper, the dry type composite film transparency to reduce the phenomenon was analyzed, hopes to be helpful to the colleagues engaged in flexible packaging industry. 1. Adhesive problem itself adhesive itself color too deep, such as deep yellow, yellow, red, sometimes even soy sauce soup as dark red, still there will be a corresponding color on the film, this reduces the transparency. Especially when large blank composite membrane is more obvious. Therefore, requiring high transparency should choose light yellow or colorless adhesive. Flexible packaging processing compound bag, now USES a two-component adhesive (mostly Alcohol soluble adhesive, resin soluble adhesive) , but does not rule out using have not sex and hot melt properties of the rubber type one-component adhesive; Transparency was in fact a general concept, judgment adhesive transparency itself, the best way is: the main agent and curing agent according to certain proportion sampling, in a transparent glass in 8-50 ℃, the curing 12 hours to pervious to light, and contrast conclusion. 2. Adhesive solution dust effect of adhesive solution mixed with dust and other particles in the environment of air dust too much or workshop. After gluing, baked blow hot air also has the dust in the tiny, glued on the rubber. Composite sandwiched between two pieces of basement membrane, there are many small points, opaque. This request will glue liquid metal mesh filter with 140 purpose, despite the insoluble particles of adhesive solution, also pay attention to the workshop cleaning and hygiene; Ground smooth not coarse, no dust, dust in the air is less, bake, air inlet can be a high number of filter or other filtering material remove dust from the air. Give full attention as a packaging enterprises to cope with work environment at the same time, such as reduce the flow of personnel, health to reach the designated position, the composite base material or composite membrane must be put to a clean place. 3. Base material affects the surface tension of the film surface tension is not high, do not conform to the requirements. It does not, adhesive solution to uniform infiltration to shrink. Dry film caused by uneven, bit by bit dry composite film transparency is not good. So, dry the surface tension of the composite membrane can in 40 because of poor; If the surface tension is not high, have to deal with it. Commonly used edm processing, processing purpose: to make the surface roughness, surface raising, increase the surface area of concave and convex. When the adhesive and its surface contact, can produce a good effect. 4. Adhesive liquidity shortage, poor flattening effect at this time to switch to liquid adhesive, or the use of solvent can improve the flattening sex. But to prevent residual solvent too much and the peculiar smell and odor problem, adhesive liquidity difference two situations: { 1} ; The adhesive itself caused by poor quality, { 2} Because the concentration is too high, or high temperature and high humidity weather and solvent evaporation too fast, and lead to poor flowing property, in order to solve this problem must pay attention to regularly check their viscosity. When change should take corresponding solving measures, such as adding diluent. Circulating pump is adopted to improve the adhesive solution for adhesive also can reduce the viscosity rise, but also improve the transparency. Glue of flowing property: small molecular weight, low viscosity, good flowing property. Transparent transparency of retort pouch in general than ordinary bags. This is the difference caused by the flowing property of different kinds adhesive. Fluidity problem for glue and glue molecular design, the choice has a lot to do. Now wipe divide evenly USES mostly dry composite machine, glue roller is a good improvement, is to improve the performance of for transparency. 5. Enough glue influence the gluing quantity is not enough, we have the blanks with the tiny bubbles and hearing the speckled or opaque. Solvent water cut is more than 0. 2%, if more than this index will react and curing agent, and consumption to reduce solid content. Not only reduce the peel strength and transparency. How much the gluing quantity and concentration of adhesive solution deployment, coated network cable roller depth, shape and arrangement. The gluing quantity how many problems is determined by the actual material structure, use again. 6. Poor transparency and composite also said, drying temperature, if the temperature control is not appropriate, into the bake, when temperature is too high, dry quickly, make the glue on the surface of the liquid solvent evaporation rapidly, causing local improve surface glue solution temperature, the surface crust. Then when internal heat into the adhesive solution layer beneath the skin membrane solvent gasification, break through the film forming ring, round to make rubber caused by uneven opaque. So should strictly abide by from low to high temperature control. Solvent evaporation from the inside out slowly, it can avoid ring phenomenon, transparency. 7. Low transparency also with compound rubber roller finish and coating network cable roller about the compound rubber roller must be smooth surface, no trace, no foreign body. Transparency is bad also associated with the web hole depth and shape of network cable roller, depth and shape decide the gluing quantity. If net hole blocked, uneven glue has transparency adverse conditions, the solution is cleaning mesh point until clean. 8. Low transparency also have relationship with curing time, especially a two-component glue performance is more obvious. General curing temperature control in 50 & ndash; 55 degrees. Time in 24 - 48 hours, there are special circumstances, the time may be longer, a large part of transparency is bad because of curing temperature, and time on the do not match.