The relationship between the index of laminating glue and common problems I. Viscosity Viscosity is the internal friction of the liquid, and colloquially, the thin consistency of the glue. The viscosity of the glue does not indicate the bonding performance of the glue, in other words, the thicker the glue is, the better the performance is. The viscosity can be adjusted within a certain range. The viscosity will mainly affect the coating leveling of the adhesive, the amount of adhesive and so on. ◎ The influence of viscosity on coating and leveling Glue viscosity has a very large influence on coating and leveling. Generally speaking, too thick and too thin glue will cause coating difficulties and poor leveling. The appropriate viscosity range is the necessary prerequisite to ensure these two items. If the viscosity is too thick, the glue is not easy to spread out after coating, and it is easy to appear a line. The glue viscosity is too low, easy to appear flower, in extreme cases will appear flow hanging phenomenon. ◎ The influence of viscosity on the amount of glue The viscosity of glue also has a great influence on the amount of glue, and the change of the amount of glue has a key role in the compound effect. Normally, the higher the viscosity, the greater the gluing, the lower the viscosity, the smaller the gluing. It should be noted that, with the change of the speed of the cots, the amount of glue is also changing. Change of glue amount: h=2/3kμu h- adhesive thickness     μ- viscosity      u- machine speed          k- constant As can be seen from the above formula, the greater the machine speed, the greater the viscosity, the greater the amount of glue, the greater the thickness of the adhesive layer. ◎  Method for the determination of viscosity The commonly used measurement methods of viscosity are outflow cup method and rotary viscometer method. It should be noted that the viscosity measured by these two methods is not the same type, and there is no conversion relationship between them. Drain cup method Commonly used is coated with 4 cup method and Chaen cup method, its principle is the same, the determination of the specified volume of liquid, through the specified diameter of the mouth of the time required, this way generally determination of low viscosity liquid, such as coated with 4 cups, for the determination of more than 120 seconds of the liquid is not applicable. It is important to note that the 4 cups is short for No.4 cup, the Chayn cup also has No.4 cup, do not confuse the application process Rotary viscometer method This method is mainly used to measure the liquid with larger viscosity. It is used to measure the resistance of the liquid in the process of liquid rotation. Common laminating glue is generally 17-30s (coated with 4 cups) The viscosity of glue used for automata is lower than that of hand motors. Four, mechanical stability Polymer emulsio...

Protective film glue transfer, there are a variety of factors, I believe that in the work, many teachers will also encounter a similar situation.The phenomenon of the so-called glue transfer is uneven coating or in the process of transportation, the glue shift remains on the surface of the profile, commonly known as glue transfer. Protective film glue transfer can be divided into the following three situations: Cohesive damage: there is pressure sensitive adhesive on the surface of profile and substrate, and the coating surface of protective film loses luster; Adhesive base damage: there are more rubber residue on the profile surface, and the substrate can be seen on the adhesive surface of the protective film; Migration residue: there is a small amount of glue residue on the profile surface, and the gloss of the coating surface of the protective film is maintained well. Cause analysis and protective Measures: Protective film production process, substrate (PET) and raw material (pressure sensitive adhesive) quality problems caused by bad Solutions Improving the process and perfecting the scientific process regulation is the guarantee of quality. The technological requirements of coating production include the allocation of glue, the amount of glue, the uniformity of coating, the proportion of curing agent, the uniformity of curing agent dispersed in the glue, the machine speed, the temperature setting, the drying effect and so on. Improve the quality of glue, such as: use pressure sensitive glue with high gel fraction, improve the degree of cross-linking with the product; The use of long carbon chain acrylate monomer copolymerization or bonding technology; Adding certain UV absorbent to reduce UV aging; Optimize the formula and glue production process to improve the heat and low temperature resistance of pressure sensitive adhesive. Is to improve the surface tension of aluminized PET film. PET itself is a polar material, both sides have a certain tension, but with the passage of time, the tension value will gradually decay, so the corona processor is used to increase the online electrical activation processing, in order to improve the bonding force of PET substrate and glue. It is to improve the crosslinking degree of pressure sensitive adhesive. The cohesiveness can be improved by improving the formula of glue and increasing the proportion of crosslinking agent. Aging of protective film The protective film consists of a plastic substrate and a pressure sensitive adhesive, both of which belong to high polymer. Aging mainly includes thermal aging and ultraviolet aging. After the aging of the protective film, the macromolecular chains forming the substrate and pressure-sensitive adhesive break, the average molecular weight decreases, the cohesion strength decreases, and then the cohesive damage occurs, resulting in glue transfer. Solution:The protective film and the profiles that have been coated with the protective film should be avoided from sunl...

Water-based glue, when the autumn and winter season, special attention should be paid to anti-freezing treatment, according to different temperatures, the implementation of different solutions. Cautions (1) Pay attention to warmth and anti-freezing when transporting glue: when transporting below 0℃, pay attention to the warmth of the vehicle, and transport below -5℃ is prohibited; (2) Keep warm and anti-freeze when glue is stored: keep warm after glue goes to the warehouse. The storage temperature of glue should be controlled at more than 5℃ to prevent ventilation and loss of temperature in the warehouse. Low temperature will destroy the adhesive performance of glue; (3) Winter glue precautions: customers should pay attention to the construction operation, in order to ensure the best adhesive performance of the glue, very low use temperature must be above 5℃, to ensure product quality; (4) If the glue storage temperature does not reach more than 5℃, it will appear: the viscosity of the glue rises, it is difficult to brush, the glue is frozen and can not be used; (5) If the glue is frozen and the specimen is not broken, the drying speed of the glue is slow, and the pressure time will be 3-4 times higher than the original time, which will lead to the quality problems of the finished products of the customers; (6) If the Water Based Adhesive can be used normally after freezing, it can be slowly softened to liquid in the room temperature environment. Usually the glue can withstand the limit of three thaws. Therefore, the glue should be kept in a warm environment in winter to avoid freezing. Professional personnel must confirm whether the thawed device can be used properly.

Label is used to show the relevant instructions of the product of the printed matter, some are on the back of the glue, but there are some printed matter is not with glue, glue label is known as "self-adhesive label". Self-adhesive label is a kind of material, also called self-adhesive material. It is a composite material made of paper, film or other special materials, coated with adhesive on the back and coated with silicon protective paper as the base paper. Self-adhesive is a general term for materials with such properties. The market demand for high-grade labels is increasing day by day, domestic has been able to process all kinds of high-grade labels, previously processed in overseas labels have gradually turned into domestic production, which is also one of the main reasons for the rapid development of domestic label printing. Application of self-adhesive labels As a form of packaging to achieve appearance and specific functions, self-adhesive labels can be flexibly applied in all walks of life. At present, the label in the pharmaceutical industry, supermarket logistics industry, electronics industry, lubricating oil, tire industry, daily chemical, food, clothing and other industries have superior application! Self-adhesive labels are roughly divided into two kinds: one is the paper self-adhesive label, the other is the film self-adhesive label. 1.Paper self-adhesive labels are mainly used in liquid washing products and popular personal care products; Thin film materials are mainly used in high - grade daily chemical products. At present, popular personal care products and household liquid washing products occupy a large proportion in the market, so the corresponding paper materials are used more. 2.Film self-adhesive labels are commonly used in PE, PP, PVC and some other synthetic materials. The film materials are mainly white, matte and transparent. Because the printing adaptability of thin film material is not very good, it is generally treated with corona or by adding coating on its surface to enhance its printing adaptability. In order to avoid the deformation or tear of some film materials in the printing and labeling process, some of the materials will be subjected to directional processing, one-way stretching or two-way stretching. For example, BOPP materials with two-way stretching are widely used. The structure of the sticker In the usual sense, we call the structure of self-adhesive label "sandwich" structure: surface material, glue (adhesive), the bottom paper, the three layers of structure is the basic structure, but also we can see the naked eye. In fact, many materials may be divided into more detailed, for example, some film surface and coating, easy to print, some materials and glue between the coating, easy to material and glue full combination and so on. The production process of self-adhesive label Simply put, the production process of self-adhesive label materials is completed by coating and composite two processes. The...