Q: What kind of pouch conditions for your company's aluminum film adhesive?
A: Our factory uses boiled aluminum film adhesives to produce boiled packaging. The boiled conditions are: the first boiled and then frozen, and then boiled for the second time before eating. The packaging structure was NY//PE, and small batch production was started. The tests were all normal. When the batch was produced, it was found that there was delamination during boiling. Why is that?
Boil for the first time, that is, boil for the first time and then boil for a second time before eating. This kind of processing technology has a higher requirement for the composite packaging of the NY//PE structure and must use a boiling-resistant polyurethane adhesive in order to meet the requirements. The aluminum-plated film adhesive itself is biased in the design of the molecular chain segment softness, the relative ratio of curing agent is relatively preserved, to prevent the excessive impact of curing agent on the aluminum, in the use of performance is not resistant to boiling adhesive.
When the NY//PE packaging bags are produced in small batches, the composite time is short, and the environmental factors, moisture and alcohol in the solvent, and the influence of factors such as easy moisture absorption of the film are basically ignored, so that the test requirements can be met. In mass production, the film, especially the NY film, is exposed to air for a long time, which is unavoidable. Part of the water vapor is adsorbed. The trace amounts of water and alcohol contained in the formulated glue solution have enough time to react with the curing agent continuously. The higher the temperature is, the faster the reaction speed is. At the same time, the faster the solvent volatilizes, the stronger the moisture in the air is absorbed. This is why summer is more likely to occur than winter. Coupled with the performance characteristics of the aluminum-plating crucible adhesive, there are boiled delamination phenomenon in mass production.
Q: What is the difference between boiled and steamed?
Answer: Cooking sterilization is divided into: low-temperature boiled packaging, boiled conditions are generally controlled at 100% sterilization for 30 minutes, there is a boiling condition controlled at 85 degrees for 15 minutes, called pasteurization; low temperature cooking packaging, cooking The condition is to control the temperature within a range of 100 degrees to 20 degrees for a certain temperature value to sterilize for 30 minutes; in the middle temperature cooking package, the cooking condition is to control the temperature at 121 degrees for 45 minutes; the high temperature sterilization package, the cooking condition is to control the temperature up to 135 degrees Sterilize for 15 minutes. Ultra-high-temperature packaging sterilization, sterilization conditions in the microwave heating box sterilization for 3-5 minutes.
Boil and cooking packaging structure is also different, boiled packaging structure, commonly used NY/CPE, PET//CPE, NY//CPP, PET//CPP, PET//PET//CPP, etc.; The commonly used cooking packaging structure is NY//CPP, PET//CPP, NY//NY//CPP, PET//PET//CPP, PET//AL//CPP, PET//AL//NY// CPP and so on.
Q: What are the requirements for adhesives in pesticide packaging?
Answer: Due to the complex composition of pesticides, there are water-soluble pesticides and oil-based pesticides, and there are also large differences in corrosiveness. In the past, pesticides were packaged in glass bottles or metal bottles. Considering the inconvenience of bottled pesticides transportation and the fact that flexible packaging materials have been adapted to the packaging of pesticides, the use of plastic flexible packaging bags to package pesticides is also a development trend.
At present, there is no domestically-to-world-wide dry-reusable polyurethane adhesive that can be applied to pesticide packaging bags 100% without any problem of delamination and leakage. It can be said that the overall requirements of pesticide packaging on adhesives are relatively high, especially on corrosion resistance, grease resistance, and particularly on solvents that are resistant to xylene. Production of Pesticide Bags Packaging Prerequisites Foot inner composite substrates require good barrier properties and are resistant to corrosion. Secondly, the adhesive is required to have strong corrosion resistance, and an adaptability test must be done during production. The soon-to-be-produced packaging bag will be packaged with pesticides, and then placed in a high temperature of about 50% in the maturation room for a week to see if the packaging bag is intact and if it is intact. It is basically believed that its packaging structure can hold this pesticide. If delamination or leakage has occurred, the pesticide cannot be packaged.
Q: Why is there a lot of air bubbles inside the rubber pan during compounding (speed 40-50 m/min), what impact does it have on compounding?
A: At a speed of 40-50 m/min, there is a lot of air bubbles in the glue in the plastic disc. The first thing to consider is whether there is a lot of bubbles before using this kind of adhesive. If there is, it means the adhesive. It is prone to a lot of bubbles. If not, consider:
1. If the solvent is replaced, the viscosity of the glue will increase when the solvent contains water or alcohol.
2. When the glue is prepared, the concentration is too high;
3. The angle control of the scraper and the too high level of the scraper from the plastic surface of the plastic disc caused a large gap between the glue liquid. When the glue liquid flowed down, the impact was large and bubbles were generated, which did not result in timely dissipation.
If there are not too many bubbles generated, at 40-50 m/min, there is basically no effect on recombination. If the speed reaches 100 m/min or more, the bubbles may be carried into the composite film. Go, resulting in speckle phenomenon.
Q: There are bubbles and spots in the composite film. What causes it?
A: There are many reasons for this phenomenon, and specific conditions must be analyzed. The common factors that cause bubbles and spots are:
1. Environmental factors such as: dust and impurities. This requires good environmental hygiene. In addition, the glue contains impurities, it is necessary to determine whether the adhesive itself or with a plastic bucket with people.
2. The prepared glue is mixed with water, and it is not dried in the drying tunnel at a temperature of 60°C-90°C. It reacts with the curing agent to produce carbon dioxide bubbles and crosslinks to produce a white crystal point. The composite film also contains air bubbles and Two kinds of water bubbles.
3. Humidity in the work environment is too high, and moisture in the air adheres to the plastic surface. In particular, plastic films with high wettability such as nylon and cellophane tend to crystallize.
4. When the adhesive is formulated, there is a regular phenomenon of “speckled or bubble†due to the lack of concentration in the over-consistency, the lack of squeegee, the lack of sizing on the roller, and the blocking of the roller.
5. The poor quality of the film, ie, the poor surface tension of the base film, results in poor leveling of the adhesive and bubbles in areas where no glue is present.
6. When compounding, the angle of the scraper and the gap between the glue liquid are large, and the impact generates bubbles. When the multi-functional machine operates at a high speed, the bubbles cannot dissipate in time, resulting in a large number of air bubbles in the plastic disk, which are then entrained and transferred to the film. (Adhesive viscosity is too high, also Generate bubbles).
7. The composite pressure is insufficient, the surface temperature of the composite roller is too low, the adhesive activation is insufficient, and the fluidity is small, so that the gap between the glue liquid dot and the dot can not be filled, resulting in tiny voids and bubbles.
8. Adhesive quality problems.
9. The effects of moisture and alcohol should be avoided during compounding.
(author/Xiao Haiyi)
-- Flexible Packaging Weekly