Basic knowledge training of food packaging bags

Basic knowledge training of food packaging bags
1. The simple production process of color bags:
a. The production process of the color bag: enter the film for printing (each color has a plate roll during printing, and the engraving of the plate roll is intaglio engraving), the ink is constantly flowing during printing, because the ink will condense , A scraper is inlaid during ink printing and film printing, and the scraper is to scrape off the ink on the protruding part of the plate roll, so that the concave plate roll can be printed. If there is dust on the scraper, strips of ink pollution will appear. For the point-shaped ink pollution phenomenon, it is because the ink is splashed on the packaging film when the ink is rolled, causing the point-shaped ink pollution.
b. After the film is printed, it starts to be compounded. Generally, the dry-wet compounding method is used, that is, the color-printed film is coated with glue and then put into a drying oven for 2 minutes and then compounded with PE. The compounding tension is 5.6kg. The packaging bags used by our company are two-layer composite.
c. Curing: Curing the film after glued and compounded. The effect of curing is mainly that the glue can be firmly stuck. Curing is generally cured at 50°C for 24 hours. In fact, the composite film is stored at 50°C for 24 hours. If the time and temperature do not meet the requirements, the film will not be tightly bonded.
d. The cured film is then inspected. The inspection is to input the printed matter of the standard model into the computer, and then pass the cured film through a white screen controlled by the computer. symbols of. After e-inspection, the film is cut
f. The film after slitting is made into a bag. The bag making is to directly make a piece of film into a bag through the machine. During the bag making process, the edge is automatically sealed and pressed.
Simple production process of white bag
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The film is blown with polyethylene and color masterbatch. During the whole film blowing process, the temperature is very high when blowing the film, and it is easy to cause some polyethylene to drop directly on the film, resulting in the appearance of grains on the packaging bag. After the film is blown, the film is compounded, and the subsequent production process is the same as that of the color bag. Therefore, the general crystal grains appear on the white bag but not on the color bag mainly because the production process is different.
3. The main testing items of the packaging bag: specification size length (mm) width (mm) building (um) appearance overprint error, color beauty, peel strength. Heat seal strength
a. The length and width are tested with a ruler, and the thickness is tested with a thickness gauge. The testing method is the same as ours.
h, the inspection of the color beauty is mainly through checking with the standard sealed sample. The color beauty should be consistent at a distance of one arm. In terms of color, the printing factory is currently using a 50 times magnifying glass to face the color of the printed matter. Check carefully, the general color is combined by dots one by one, if the color is wrong, the dots will be distributed irregularly. Generally, the dots are regular and the dots are circular. c. The inspection of overprint error is mainly to visually check whether there is printing double image.
d. Peeling strength and heat sealing strength are mainly tested by AGS-5KNG electronic universal testing machine, and the testing principle is the same as that of our computer tensile tester.
e. The detection of peel strength is mainly to cut the packaging bag into strips of about 15mm baskets with a blade, crumpled one end of the packaging bag with a blade, and then artificially layer it, and check the tensile force on both sides of the layered packaging bag Clamp a piece on one side of the instrument and then operate it with a computer tension instrument. Its peel strength can be tested. f In addition, the manufacturer can also test the oxygen permeability rate of the packaging bag. The instrument used for testing is MT-C1 constant temperature gas oxygen permeability test device.
9. Attached are the graphs of MT-C1 constant temperature gas oxygen permeability test device and GS-5KNG electronic universal testing machine
4 Characteristics of packaging bag materials:
a. Nylon: It should be sealed and packaged, because nylon will absorb moisture when it encounters air. The main characteristic of nylon is that it has strong penetration resistance and is suitable for products made of bone. However, nylon packaging bags are easy to wrinkle and shrink. The thickness of nylon is generally 15um.
b. OPP: brittle, with better air permeability and moisture permeability, poor stretchability and barrier properties, and relatively brittle hand feeling. The thickness of OPP is generally 30um. c. PE: The tensile performance is better, and the breaking force is better. There are two kinds of milky white PE (dull) and transparent PE. It feels softer.
d. PET: good stiffness, good printing effect, suitable for outer packaging bags. It feels very crisp, and the rustling sound is very loud when you hold it in your hand. The thickness of PET is generally 12um. e. CPP: Good transparency.
Note: The shrinkage rate of various materials is about 4%-5%. The packaging bags used by our company are generally made of nylon and PE. A copy of each material has been sampled for backup as a sealed sample.
, the material detection of the packaging bag