The adhesive strength of the finished composite film is reduced, and the peel strength is poor, which is related to various factors. Such as: the effect of adhesives, the surface tension value of the composite substrate does not meet the requirements, the peel strength is affected, the operation process is not standardized, the effect of the drying temperature, the temperature of the hot steel roller is not suitable, and the effect of the film substrate additives. Now give analysis and find suitable solutions to minimize the failure phenomenon of poor peel strength. The type and quality of the adhesive are not compatible with the substrate to be compounded and affect the peel strength The composite film for different purposes should choose the appropriate substrate and adhesive. For example, when no aluminum foil is involved in compounding, general-purpose adhesives are sufficient. If aluminum foil is compounded, and the end use is to package liquid hot and spicy foods (such as mustard, juice, soy sauce, peanuts and OTHER foods), it is necessary to choose a special adhesive for aluminum foil that is resistant to sour and spicy substances. When choosing an adhesive for aluminum foil, the adhesive with slightly larger molecular weight, more uniform molecular weight distribution, good solvent release, and good coating performance should also be given priority. Although the adhesive with small molecular weight has good coating performance, it has strong molecular mobility and will penetrate through a very thin aluminum layer, resulting in reduced peel strength and reduced adhesion. If the composite bag is to be sterilized by high-temperature cooking, high-temperature (or) cooking-type adhesives should be used. General adhesives should never be used. The general adhesives are not temperature-resistant, and the composite film will usually delaminate before reaching the packaging. Requirements for peel strength. Our company often uses PU1750 and PU1875 adhesives produced by Zhejiang New Oriental Ink Group Huaguang Resin Company for high-temperature cooking and sterilization packaging. The effect is good. It can reach 10-12N / in PET / CPP structure. In PET / AL, NY / AL The composite strength in the structure reaches 10-12N /. For the 15µPA / 70µm LDPE composite structure, 300 type PU-1875 polyurethane adhesive is not used, and the effect is good. When using this adhesive, it is necessary to pay attention to several points: 1) After the corona treatment of the film, the surface of the basket should reach 3.8 × 10¯²N / m Only the above can obtain the ideal bonding effect; 2) diluent often uses ethyl acetate or ethyl acetate, where the water content should not exceed three ten thousandths, the alcohol content should not exceed two ten thousandths; 3) Do not mix in the glue Into a solvent containing active hydrogen. Such as: water, alcohol, amines; 4) The ratio of PU-1875 adhesive is the main agent: curing agent: ethyl acetate = 1: 0.2: 1.8 (weight ratio), the best performance. Adhesive does not penetrate the ink well and floats on the surface of the ink, and the adhesion between the ink and the substrate is not good. It will also cause the lamination of the composite film, which is manifested in the place where the ink is present, especially the multi-color overprinted parts . The ink is pulled down by the adhesive. The use of high solid content adhesive has sufficient time to penetrate into the ink layer and reach the surface of the printing substrate. Appropriately increasing the amount of gluing will help improve the compound fastness. Choosing the appropriate ink, and increasing the surface tension of the printing substrate to improve the adhesion of the ink is also one of the solutions to the problem. In the compounding process, the adhesive is required to have good fluidity and good flatness. If the adhesive deteriorates or becomes cloudy, it cannot be used after being emulsified. Therefore, when preparing the adhesive, it must be prepared in an appropriate amount according to the needs. Insufficient amount of sizing, uneven coating will directly affect the adhesion and peel strength Insufficient coating amount of adhesive, uneven coating will also lead to lower peel strength and lower adhesive force. This is most likely to occur in the use of single-component hot-melt adhesives. It cannot be ignored. When using single-component hot-melt adhesives At this time, the concentration of the main adhesive will directly affect the peel strength. We have noticed that if the inner layer thickness in the BOPP / OPP, BOPP / VMOPP, BOPP / OPP composite film exceeds 30µm, the peel strength is most likely to decrease. If a single-component adhesive is used, a small section of the composite product should be taken for peeling test during the compounding process, and the corresponding records should be made at the same time. In general, the main rubber: ethyl ester ratio is 50:50, and the effect is good. The amount of gluing is determined by the volume of the anilox roller, and it is inseparable from the operating concentration. If the adhesive concentration is high, the substrate tension value is appropriate, the amount of glue is also moderate, and the peel strength of the composite film is still not ideal, you should consider replacing the anilox roller to increase the amount of glue. The general specification of the anilox roller is 80μm, 100µm, 120µm, 140µm, adjust or select according to the actual compound. Thinner purity is not high enough, will affect the composite peel strength The role of the thinner is to increase the fluidity of the adhesive, improve the spreadability, and better spread evenly, so that the glue solution can infiltrate with the substrate better. If the purity of the thinner is not high, it contains active substances such as water, alcohol, etc. , It will consume a part of the curing agent, causing the actual ratio of the main agent and the curing agent in the adhesive to be out of balance, and the adhesion will be reduced. There are three points that the peers should learn from when choosing the solvent: 1) The purchase must be from a regular, quality-guaranteed manufacturer ; 2) Sampling inspection of each barrel after purchase and found to contain water or alcohol active substances, must be banned, only use high purity solvents to ensure that the composite film has strong adhesion; 3) Before use, the solvent It must be clean. If there is dirt or other phenomena, it is best to filter or deal with it separately. Be careful not to affect the coating effect and affect the peel strength. Effect of drying temperature In the compounding process, the temperature of the hot pressing roller of the drying tunnel should be adjusted according to the actual situation. Generally, the temperature of the hot pressing roller should be controlled at 50. In the drying device, the more complete the volatilization of the solvent, the greater the peel strength. The temperature runaway also affects the peel strength, and the adhesive strength is also reduced. Generally, the temperature of the inlet is appropriate, and the temperature in the second and third zones will increase accordingly. If the temperature of the inlet is too high, only the surface of the film will be dried, and the inner layer cannot be dried, which will not only affect the peel strength, but also produce odor. Rouge,Highlighter,contouring makeup,makeup lotion Guangzhou Boxuanya Cosmetics Co.Ltd. , https://www.cosmeticsbxy.com