Caused by "difficult to bond"


With the progress of social civilization and the demand of the market, more and more new materials and processes have been applied to the packaging industry, and bonding has become an important material that combines the complete packaging of a product and is increasingly used. In the packaging industry, during the process of domestic production and sales of various printing and packaging adhesives, we have had many contacts with many domestic printing and packaging companies. During this contact process, we have discovered that many manufacturers (Including some large-scale printing and packaging plants), they are experts in printing, but the understanding of viscose is not enough, many of them are even blind in selecting and using adhesives, and this brings them to all manufacturers. Big losses and waste. "Difficulties in bonding" has become a specter that has plagued packaging companies, causing headaches to almost every packaging and printing factory.
Our company is a professional manufacturer of printing and packaging adhesives. We believe that as long as you choose and use good adhesives, the problem of "difficult to bond" can be completely solved. Combining the experience and lessons of many manufacturers, the problems are in the "select, use" these two links, in order to allow many engaged in technical work, quality management, supply work colleagues to learn more about adhesives, so that "bonding difficult" To become "adhesion-easy", from "worry about glue" to "be safe", we have compiled this handbook to discuss the production and use of adhesives with our domestic counterparts and make our country's packaging industry prosperous. contribution.
How to choose adhesive
1) understand the use of characteristics Any kind of adhesive is not a panacea, a viscose can only be suitable for a certain type or a specific type of sticky material. Some manufacturers' blindly using plastics for “try it for a try” is a waste of time and energy, and it also causes great losses. Nowadays, BOPP/paper, polishing/paper, PET/paper, and high-light printing paper/paper are commonly used in various packaging factories. In fact, this kind of product only needs one kind of product from our company, that is, 810 sealing glue. Colloids can adapt to all the requirements of the above products, and 98% of all packaging companies are the above ones. In addition, there are some manufacturers such as PVC / paper, PVC / wood, UV / paper, etc. These products can be used to solve other models of our company's plastic. (such as PVC glue, 818UV special sealing glue)
2) Quality standards as an adhesive, the most important quality standards: A, adhesive strength (adhesion); B, high temperature resistance; C, low temperature resistance; D, aging resistance; E, maintain adhesive strength Sex. Many domestic packaging plants appear to have poor adhesion or brittle products for a period of time. Degumming is basically the same as above. Therefore, some printing and packaging factory colleagues often hear that “some gels degumming days, some gels degummed on cold days, and some glues do not store on cold or hot days” is not a long-term argument. This is actually a profound understanding of the quality standards of plastics. As a result, even some factories that manufacture viscose do not know why they are degumming, so it is not surprising that there are quality problems in the production process.
3) Performance Our 810 sealing glue and 818 sealing glue are miscellaneous multifunctional paper-plastic adhesives with strong initial adhesion, high bonding strength, good resistance to high and low temperature, good adhesion and retention, good moisture resistance and adhesion. Wide range of coverage, only one or two kinds of plastic to meet the full bonding requirements of the current packaging plant (BOPP / paper, polishing / paper, PET / paper, UV light / paper, ink / ink), and by many manufacturers welcome. The disadvantage of miscibility is that the cleanability of the container utensils is somewhat poor, and the wild glue is wiped with a solvent (due to good moisture resistance). Therefore, when choosing viscose varieties, manufacturers should understand the characteristics and performance of each variety and adapt to their actual conditions. At the same time, we must also have a certain understanding of the production plants that provide viscose, such as whether the products are mature, the stability of the products, the understanding of the products, and the technical strength. Otherwise, the blind use of plastic is a great hazard, because the viscose products have hysteresis, many degumming is only a few days or even months later, so the use of plastic must be careful.
4) Price The choice of adhesive, quality is certainly the first, the price second. Some manufacturers blindly believe that the higher the price is, the better the quality is, or the lower the price is, the worse the quality is. These views are very one-sided, and therefore some manufacturers have both spent money and caused great losses. In fact, viscose only occupies a small proportion of the cost of a packaged product. Therefore, we believe that firstly, under the premise of understanding product characteristics, understanding quality standards and performance, we should seek a suitable price. We think this is reasonable.
Adhesive properties and inspection methods for sealing glue A batch of finished product packaging boxes is not immediately used, and it is sometimes possible to stock for several months or even a year. Therefore, it is very important for an adhesive to have good cold and heat resistance and good aging resistance. For example, some packaging boxes work well for a short period of time, and after a period of time, degumming and film brittleness have occurred. So in the end to determine a kind of adhesive bonding performance in the end how to do the following aspects of the test.
First, tear a tear on the bonded package along the edge to see if it is torn by the adhesive substrate and apply a nail to the paper base attached to the film. If only a small piece of paper can be removed at a time The lack of paper base on the base or simply indicates that the adhesive has good adhesion on the film. Plastic/plastic sealing glue Because the two adhered surfaces are BOPP film, the film can not be destroyed due to its strong flexibility, so it can be felt that the two adhered surfaces have strong adhesive force during inspection.
Second, the bonded packaging box (at least one day has been placed) placed in a thermostatic oven at 60 °C baked for 72 hours out of the cooling after the seam or bottom does not pop open, while the hands do not degumming the packaging box, The film was not brittle, indicating no problem with the heat resistance of the adhesive.
Third, put the bonded packaging box (at least one day has been placed) in the freezer of the refrigerator and freeze it for 72 hours. After the box is dry, the box is not degummed and the film is not brittle. The adhesive has no problem with low temperature resistance.
Fourthly, the adhesive products adhered by the first three kinds of adhesives will be stored. Some samples will be tested every two weeks, one box will be tested, the hands will not be debonded, the film will not be brittle, and there will be no problem during the continuous inspection for six months. The glue can be used with confidence.
Analysis of Common Problems and Causes of Sealing Gloves in Use and Storage of Finished Products
1. Problems that may easily occur in the bonding process:
(1) If the amount of glue is too thick, glue overflows after pressing, which not only affects the appearance of the product, but also tends to cause blocking between the boxes. In this case, it should be left to dry for 2-5 minutes after gluing. After the adhesive is slightly dry, it should be pressed. (2) The glue brush is too thin and the open time is too long, resulting in poor adhesive fastness, and sometimes there is no adhesion at all. When this happens, read the instructions or consult the manufacturer. (3) There is no pressing or the pressure is too small and causes the bonded product to spring open automatically. This is mainly because the product with larger stiffness must be squeezed for at least half an hour, because many adhesives are contact adhesive. Therefore, the two adhered surfaces must be effectively pressed together. In the unit time, if the adhesive force is lower than the elasticity of the product, the product will spring open, so the general product requires a 0.5 hour press time. (4) In order to save the use of laminating adhesives and emulsion polymers, some manufacturers mix them with stickies or use larger amounts of water to dilute the adhesives, resulting in insufficient adhesion fastness and poor adhesion on the film. This situation is very dangerous and it is a serious violation of the bonding principle and technology. It is hoped that users of adhesives must not blindly use plastic and cause greater losses to themselves.
2. Problems in the process of storage of the bonded product The degumming phenomenon occurs in the box in the winter. The main reason is that some adhesives have poor low-temperature resistance, and the loss of activity on the surface of the adhesive below 5°C results in a decrease or disappearance of the adhesive strength. (2) In the hot summer, the sticky packaging box pops out and debonds in the warehouse or transport box. The main reason is that the high temperature resistance of the adhesive is not good, and the adhesive layer becomes soft at a temperature of 50-60° C., and the strength becomes smaller, which leads to degumming of the packaging box. (3) In the early stage of tackiness (within half a month), the packaging box has a good bonding effect, and the degumming of the packaging box occurs with the prolonged time. The main reason is that the adhesive itself has poor adhesive properties, most of which are plasticizers added to the adhesive. As time goes by, the plasticizer migrates to the paper base, causing the adhesive layer to become hard and brittle and the product degummed. On the other hand, because the adhesive contains a large number of unsaturated bonds, the anti-aging properties of the product are not good. The storage period is prolonged and the film becomes brittle. The product is degummed. (4) The warehouse is very humid and stored for a long time. Not only the humidity of the product exceeds the standard, but also degumming of the product occurs. The main reason is that the product absorbs moisture, and the water resistance of the adhesive itself is not good, resulting in soft delamination of the adhesive layer. The series of sealing glues we produce have a certain degree of water resistance, so the spilled glue must be wiped with solvent, and the use of water and solvents for container cleaning is the reason.
The characteristics of water-soluble adhesive film and its application method The adhesive film's laminating mechanism is to apply the liquid glue evenly on the film and then wet it directly with the printing paper to achieve the purpose of bonding through the penetration of adhesive molecules. Several issues worth noting in the compounding process are proposed for your reference.
1) The adhesive is a water-based adhesive, and the printed matter to be composited must have strong water absorbability, and the printed matter with poor water absorbability cannot be compounded with this kind of glue.
2) For print products such as gold ink, it must be the first sample, only the gold ink without color reaction can be used in batches.
3) The product on the rewinding roll can only be opened after the film is transparent. It takes about 20 minutes.
4) If it is necessary to press and emboss the laminating product, it must be held for 24 hours.
5) If the paper jam after laminating is caused by the phenomenon of four corners warping, it may be too much glue, resulting in too much shrinkage stress of the adhesive layer, or the moisture content of the jam is too high and should be controlled.
6) The glue of different manufacturers can not be mixed, so as not to produce glue polymerization, etc., affect the laminating effect.
7) For air temperature below 10°C, the low temperature activity of the glue must be checked before use. If the low temperature performance is not good, the water bath heating method must be used to make the glue temperature above 10°C. In order to achieve full bonding purposes.
Inspection method of film quality
1) Rolling test method Take a suitable area of ​​the film sample, rub it back and forth with both hands like clothes to see if there is no peeling or blistering between the plastic film and the printed product, and the adhesive is firm without peeling, indicating that the product quality is reliable.
2) Tear-off inspection method Put the plastic film layer on the film proof, peel it off by hand and tear it off to see if the printing ink layer can completely adhere to the film or tear the paper base. If yes, the compound is normal.
3) Pressurized test method Take the film proof sheet to the die-cut creasing machine or letterpress printer. After pressing with a die cutter or a relief plate, see if there is a whitening phenomenon at the pressurization point. No whitening phenomenon indicates that the lamination quality is good.
4) Warming test method Put the film proofs into the drying tunnel and bake at a temperature of about 65°C without stripping, no foaming, and no wrinkling.
5) Water immersion test method After laminating the film sample into room-temperature water for about 1 hour, the film layer is not separated from the printing paper, indicating that the film layer is firmly attached.
Special problems in the use of special-purpose plastic packaging (glue-wax, flat-glued) and their countermeasures. Nowadays, the use of glued surfaces (corrugated and facing) has caused chaos.
1, the use of oxidized starch and water glass glue This glue is cheap, there is a certain viscosity, so in some low-grade packaging and low cost requirements are still in use, but because this type of plastic is very strong, so sometimes packaged hair Yellow, soft, hygroscopic, and brittle, affecting the printing surface of the ink occurs from time to time, and is a low-grade viscose that should be eliminated.
2, the use of polyvinyl acetate emulsion modified rubber This type of adhesive is environmentally friendly viscose, bonding strength, fast drying, now

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