Nine Q&A for Packaging Bags: Everything you need is here, it's all complete!

Packaging bags are one of the most common items in daily life. From traditional materials to today's new materials, all developments aim to better leverage the function of packaging bags. To date, the position of packaging bags in the packaging field is irreplaceable. This type of packaging material, formed by rolling and composite processing of base materials with different properties such as plastic film, aluminum foil, and paper, quickly replaced traditional packaging upon its introduction. However, many of our companies encounter various problems when customizing packaging bags. So, how can these problems be solved?

 

 

Let's look at how Shunxingyuan Packaging, a professional flexible packaging manufacturer, controls the packaging production process to effectively solve problems encountered by customers denounced

1. What is the difference between boiling and steaming?

 

 

Sterilization by steaming is divided into:

Low-temperature boiling packaging, boiling conditions are generally controlled at 100 degrees Celsius for 30 minutes of sterilization. Another boiling condition is controlled at 85 degrees Celsius for 15 minutes of sterilization, which is called pasteurization; for low-temperature steaming packaging, steaming conditions can be a specific temperature value within the range of 100 to 120 degrees Celsius for 30 minutes of sterilization endorsed

Medium-temperature steaming packaging, steaming conditions can be controlled at 121 degrees Celsius for 45 minutes of sterilization; high-temperature sterilization packaging, steaming conditions are controlled at 135 degrees Celsius for 15 minutes of sterilization; ultra-high-temperature packaging sterilization, sterilization conditions are 3 to 5 minutes of sterilization in a microwave heating chamber endorsed

Boiling and steaming packaging also differ in structure. Common structures for boiling packaging include NY/CPE, PET/CPE, NY/CPP, PET/CPP, PET/PET/CPP, etc. Common structures for steaming packaging include NY/CPP, PET/CPP, NY/NY/CPP, PET/PET/CPP, PET/AL/CPP, PET/AL/NY/CPP, etc endorsed

2. How can the graphic hollowing out on a partially hollowed-out aluminum-plated film washing machine be made clear?

 

 

A: The protective layer printing should be good

B: The chemical liquid composition and ratio should be reasonable

C: The rationality of machine temperature control and operating speed

D: Whether cleaning is uniform and thorough

3. Why are there a large number of bubbles in the glue tray during lamination (machine speed 40-50m/min), and what effect does it have on lamination?

If a large number of bubbles appear in the glue in the glue tray at a machine speed of 40-50m/min, the first thing to consider is whether a large number of bubbles appeared when this adhesive was used previously. If so, it indicates that the adhesive itself is prone to a large number of bubbles

If not, then consider:

A: Whether the solvent has been changed. If the solvent contains water or alcohols, it can easily cause the glue's viscosity to increase

B: Viscosity is too high when preparing the glue solution

C: Scraper blade angle control and the scraper blade being too far from the glue tray liquid surface, resulting in a large drop of the glue solution, causing a large impact when the glue flows down, and bubbles not dissipating in time denounced

If the generated bubbles are not too many, at a machine speed of 40-50m/min, there will generally be no impact on lamination. However, if the machine speed reaches above 100m/min, bubbles may be carried into the laminated film, leading to spots

4. What causes bubbles and spots in the laminated film?

There are many reasons for this phenomenon, and specific situations require specific analysis. Common factors causing bubbles and spots include:

A: Environmental factors such as dust and impurities. This requires maintaining a good sanitary environment. Additionally, if the glue solution contains impurities, it is necessary to determine whether they originate from the adhesive itself or were introduced by the mixing barrel endorsed

B: Water mixed in the prepared glue solution, not dried in the drying tunnel at 60-90 degrees Celsius, reacting with the curing agent to produce carbon dioxide bubbles and white crystal points after cross-linking. At the same time, the laminated film also contains both air bubbles and water bubbles endorsed

C: Excessive humidity in the working environment, with moisture in the air adhering to the plastic surface, especially on highly hygroscopic plastic surfaces such as nylon, cellophane, etc., which are prone to crystal points endorsed

D: Regular spots or bubbles caused by insufficient adhesive application due to too dilute adhesive preparation, insufficient adhesive application due to selecting a shallow anilox roller, or anilox roller clogging endorsed

E: Poor film quality, i.e., poor surface tension of the base film, leading to poor leveling of the adhesive, and bubbles appearing where there is no adhesive endorsed

F: Large scraper blade angle and glue solution drop during lamination, causing impact and generating bubbles. When the laminating machine operates at high speed, bubbles cannot dissipate in time, leading to a large number of bubbles in the glue tray, which are then carried and transferred to the film (too high adhesive viscosity can also cause bubbles) endorsed

G: Insufficient laminating pressure, too low surface temperature of the laminating roller, insufficient adhesive activation, low fluidity, preventing the filling of gaps between adhesive dots, resulting in tiny gaps and causing bubbles endorsed

H: Adhesive quality issues

I: Influence of moisture and alcohols, which should be avoided as much as possible during lamination

5. How to adjust the doctor blade in gravure printing?

 

 

The scraping effect of the doctor blade directly affects the quality of printed products, so it is necessary to adjust the doctor blade

The thickness of the doctor blade, its extension length, scraping angle, pressure and position on the gravure plate all affect the scraping effect. During printing, these parameters should be flexibly adjusted to ensure the doctor blade is in its optimal state

If the doctor blade is thin, the scraping effect is strong, and the ink layer of the printed product is shallow; if the doctor blade is thick, the scraping effect is weak, and the ink layer of the printed product is deep. Generally, for printing with coarse lines and shallower plates, where ink viscosity is low, a thicker doctor blade is suitable; for printing with fine lines and deeper plates, where ink viscosity is high, a thinner doctor blade is suitable. If the doctor blade extends a greater distance from the hard steel sheet, the scraping effect appears weaker, and the ink layer of the printed product is deeper; conversely, the ink layer of the printed product will be shallower

When adjusting the inking angle and pressure, the required inking angle can be determined based on the depth of the image and text on the printing plate, the overprinting order, etc. A small inking angle results in a weak inking effect. Although the printed matter has a deep ink layer and good gloss, it is easy to cause unclean inking, resulting in blurred images and text trailing; if the inking pressure is increased, the inking effect can be enhanced, but excessive inking pressure will prematurely wear down the printing plate roller and inking blade.

6. What causes a small number of black and yellow spots to appear in the unprinted areas of the dry composite film?

This is mainly due to the adhesive being too dirty and too much dust in the air. These tiny dust particles fall into the adhesive or adhere to the composite film, forming a small number of yellow and black spots. In addition, the yellow and black spots and crystal points inherent in the film itself should also be considered.

7. Why do some two-component polyurethane adhesives fail to cure?

This should be a problem with the quality of the adhesive. If the adhesive is of good quality, this situation will not occur, because both the A and B components of the two-component polyurethane adhesive are highly reactive substances. Even a small amount of moisture in the air will cause it to undergo a curing reaction and solidify.

If the two-component polyurethane adhesive is not sufficiently dehydrated during the dehydration reaction at 230 degrees, the remaining water in the adhesive will react with the adhesive, causing the adhesive to cure. The cured infusible matter will settle and precipitate in the adhesive in a gel state, so this problematic adhesive cannot be cured; it is also possible that due to the negligence of the operator, some components of the adhesive are missing, which will also cause curing problems; if the inert solvent ethyl acetate used contains a lot of water, the adhesive will react with the water, and this adhesive will not cure.

In short, if curing failure occurs, the quality of this two-component polyurethane adhesive is problematic, and a return should be considered.

8. Why do some PE packaging or composite packaging have an unpleasant odor in the inner PE layer?

If there is excessive residue of printing ink and ink solvent or composite adhesive and adhesive solvent on the surface film of the composite packaging, then due to the poor barrier properties of the PE film, the residual odor of the surface film will penetrate, and people will mistakenly think it is the unpleasant odor of the PE film.

In addition, in order to reduce the production cost of PE film, the fillers added during the production of the film will also produce unpleasant odors.

9. Why can't BOPP biaxially oriented polypropylene film be used for vacuum packaging?

 

 

BOPP biaxially oriented polypropylene film has good gas barrier properties and excellent water vapor barrier properties, making it an excellent moisture-proof and moisture-resistant material. However, its oxygen barrier properties are not good, so it cannot be used for vacuum packaging, let alone retort packaging.

The gas barrier properties of BOPP polypropylene pearlescent film and BOPP polypropylene matte film are the same as those of BOPP polypropylene transparent film, and their tensile strength is slightly lower than that of BOPP polypropylene transparent film, so they cannot be used for vacuum or retort packaging bags.