Bond strength and deinking Bond strength is one of the most important indexes of glue properties. Bond strength refers to the amount of force required when the film and paper are stripped, and this index is often combined with the deinking effect. We first need to understand the principle and structure of paper-plastic composite. If you want to enhance the bonding force, you must consider the rationality of the bonding force of each layer. As can be seen from the figure below, the composite bonding force mainly includes: 1) Adhesion between ink and paper 2) Adhesion between adhesive layer and ink 3) Adhesion between film and adhesive layer Relationship between various peeling effects, adhesion, and deinking ▲Peel off completely from the paper and deink completely When completely deinking, there are often two situations, one requires a stronger peeling force, while the other is completely opposite, only a lower peeling force is required to completely deink, the main reason for these two different results is The reason is the difference of paper. 1. The peeling strength is high, which means that the bonding force of the other two layers is greater than the bonding force of ink and paper, and the effect is better. This is also the best composite effect pursued by most composite manufacturers. 2. The peeling strength is low. One reason is that the bonding force between ink and paper is poor, or the ink has false drying phenomenon. The more reason is that the surface of the paper is loose, which is especially common in the compounding of gray and white cardboard. The surface layer of gray-white cardboard has a lot of fillers. If the glue cannot completely penetrate the surface layer and combine with the slurry layer after compounding, it will occur on the surface layer during peeling, and the peeling force required at this time is very small. ▲The ink layer is disconnected, part of the ink is on the film, and part is left on the paper (Partial deinking schematic renderings) This peeling state should be the most ideal peeling effect, indicating that the bonding force of each layer is very good. But pay attention to the situation of gold and silver ink, the surface layer of gold and silver ink is very similar to gray and white cardboard, it is composed of copper powder or aluminum powder and some binders, its internal structure performance is not very good, the ink layer is relatively loose, peeling off It is easy to separate during the period, and the peeling force is very small. ▲The adhesive layer is separated from the ink layer without deinking This situation shows that the adhesion between the adhesive layer and the ink layer is insufficient and the effect is poor. There are several reasons for this situation: 1) The glue is very hard, especially the summer glue is used in winter. 2) The temperature and pressure of the pressure roller are not enough during compounding, so that the glue cannot fully deform and penetrate into the ...

Hot melt adhesive (English name: HotGlue) is a kind of plastic adhesive, in a certain temperature range, its physical state changes with the change of temperature, but the chemical properties remain the same, its non-toxic and tasteless, belongs to environmental protection chemical products.Because the product itself is solid, easy to package, transport, storage, no solvent, no pollution, non-toxic type; As well as simple production process, high added value, bonding strength, fast speed and other advantages are favored. Environmentally friendly water-based adhesive is environmentally friendly. Water-based coated adhesive is a way to process the surface of printed matter, improve the gloss and strength of the surface of printed matter, and enhance the aesthetic effect. To measure the quality of the film, it is also necessary to examine its brightness, strength, bonding force and so on. Waterborne wet laminating is characterized by its high strength, easy recovery, no pollution and so on. To this end, we launched our own water-based film adhesive! Definition and classification of laminating adhesives Laminating glue refers to PET, BOPP film composite on the paper of a kind of glue. In the post-press process of the printing and packaging industry, the film coating improves the brightness of the printed matter, enhances the water resistance, makes the ordinary paper have the advantages of film and paper, and provides a beautiful visual effect for the packaging. Laminating adhesive includes water and oil - based two. In the domestic now water-based coating adhesive, most of the water-based acrylic emulsion system. Classification of laminating adhesive 1. According to chemical properties 2. According to the composite process Wet composite and dry composite Wet composite although the machine covers a small area, less power consumption, simple operation, but the finished product of the composite toughness is poor, poor adaptability to gold and silver ink, high-grade products simply cannot meet the requirements, with the maturity and perfection of water-based dry coating adhesive, people are more and more like to use water-based adhesive dry composite. 3. According to the printing method Lithography and intaglio printing Lithography is characterized by ink printing on paper and glue coating on the corona side of the film. At present, paper - plastic composite is mainly offset printing. This kind of compound equipment is relatively simple, compound speed is slow, gluing amount is large. There are two ways of gluing on mirror roller and mesh roller. Gravure printing is mainly characterized by ink printed on the film, glue coated on the film ink side. This way is film and film composite, in the paper and film composite application ratio is not high, but some special paper will use this composite way, this kind of composite equipment is relatively complex, composite speed is fast, less glue, more use of mesh roller glue, glue amount can be adjusted according...

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...