Heat sealing is the welding of plastic films. There are many welding methods. There are manual welding, high frequency welding, pulse welding, ultrasonic welding, etc. Different types of plastic bags should be used with their corresponding welding methods in order to obtain good results ( See table).
Commonly used plastic film welding method
Film Type\Welding Method High Frequency Welding Hot Plate Welding Pulse Welding Ultrasonic Welding Polyethylene ◎◎○Polypropylene ◎◎◎Soft Polyvinyl Chloride ◎◎○○Unplastic PVC ○○○○ Polyvinylidene Chloride ◎○○○ Polystyrene × ○ ◎ ◎ Polyvinyl alcohol ○ ◎ ◎ ◎ Polyester × × ○ ○ Polycarbonate × ○ ◎ ◎ Nylon ○ ◎ ◎ ◎
Note: ◎ current methods; ○ possible methods; × difficult or extremely unfavorable methods. Comparison of various welding methods
Compare Project\Welding Methods High Frequency Welding Hot Plates Welding Pulse Welding Ultrasonic Welding Suitable for a wide range of film thicknesses. Medium Thin Films Thin Thin Films Preheating Time Short Short Welding Cycles Short Long Medium-Mid Weld Appearance Good Excellent Can Consecutive Welding Can Cocoa Mold Cost Cheaper Cheap High Mold Life Long Short Equipment Cost Highest Cheapest Cheap High
26. What are the requirements for plastic packaging and printing technology standards? The main contents of the plastic packaging printing standard (GB-82) are as follows:
(1) Specification quality requirements. 1 product specifications: plastic film bag 100 × 200mm or more, the error ± 4mm, the following error ± 3mm. 2 pattern position (width): 100mm or less allowable error ± 2mm. The allowable error of 101 to 200mm is ±3mm. The tolerance of 201 to 400mm is ±4mm. 3 Ink: The hue is correct, bright, uniform, and bright. 4 Overprint: Overprint accuracy, the error is not more than 0.3mm. 5 Netting: The pattern is clear and distinct. 6 text lines: clear and complete, not deformed. 7 Sealing: flat, firm, and tightly sealed. 8 Compound: Uniform, firm, no blemishes, no bubbles, only a single bubble with a diameter of no more than 1mm in the secondary area within 10cm2. 9 Appearance: The finished product is clean and does not allow obvious dirt.
(2) Inspection methods and acceptance rules. 1 Finished product specification: pattern position and overprint tolerance, measured with a ruler, tape measure, scale magnifier. 2 Ink color fastness test: Using a medical tape on a 100×20 mm printing surface, a slow stick-adhesion was measured twice. 3 Sealing fastness test: Inflate the bag and hit with the palm of your hand. The bag is broken and sealed. (4) Sealing test: The water in the bag shall be hung for ten minutes without sealing. 5 Remaining indicators: Put a liner on the bag and visually measure it with a five-fold magnifying glass at a distance of 500mm. 6 when the user unit acceptance; can be removed in 1 ~ 2 packs of appropriate sampling inspection, if found unqualified, can be doubled unpacking inspection, qualified goods, if still not qualified, according to the circumstances can be repaired, make up, compensation.
(3) signs, packaging, transportation and storage. 1 mark: The package is affixed with a conforming inspection label, indicating the user unit, product name, quantity, manufacturer name, date of manufacture, and inspector code. 2 Packaging: According to the requirements of the user unit packaging, no requirements, according to the product area, quantity, with a more solid packaging paper sub-bundling and solid, sub-container volume, the number of balanced, in order to profit points, storage. 3 Transportation and storage: Prevent moisture, exposure, hot grilling, oil stains, ramming, and heavy pressure. The storage period should not exceed three months.
27. What is plastic ink?
Plastic ink is a process in which fine pigments, binders, fillers, and various additives are mixed and ground according to a certain amount of mixing, so that the pigments are uniformly suspended in the liquid binder to form a colored, Delicate, relatively stable colloidal material.
Plastic ink is the most important material for plastic packaging and printing. If you are not familiar with its composition and characteristics, you cannot master the use method correctly and it is difficult to obtain the ideal product. In addition, plastic ink is a flammable dangerous goods, so the transport is limited, if there is a certain color ink in the production process, in order to not affect production, have to grind some emergency ink. The necessity of studying plastic inks and supporting solvents can be seen.
28. What is the role of surfactants in inks?
Printing inks are generally stable, and this stability, in addition to the dispersion of the pigments and the viscosity of the binders, also has the effect of surfactants. The ink suspension contains a certain amount of surfactant and the pigment particles are surrounded by the surfactant. Due to the affinity between the surfactant and the binder, the wetting, penetration and dispersion of the pigment are enhanced, and the cohesion of the solid particles is destroyed. Make ink with good printing performance.
29. What is a surfactant?
Surfactants are also known as surfactants. It is a generic term for all kinds of generic compounds. Such as wetting agents, dispersants, emulsifiers and so on. Substances that can significantly change (decrease) the surface tension of liquids or interfacial tension between two phases. The molecule contains both hydrophilic and hydrophobic components, tends to concentrate in the liquid at the interface between the liquid and the other phase, forms a thin molecular film and lowers the tension, thereby effecting wetting, emulsification, and dispersion. many kinds of. Generally divided into cationic surfactants, anionic surfactants, non-ionic surfactants (such as polyoxyethylene castor oil used in ink dispersant). In addition, there are amphoteric surfactants and so on. By the 1970s, it had reached thousands of types, and its application has become more and more extensive. It is an indispensable important raw material for the manufacture of inks, coatings, and pigments.
30. What is the connection material?
The binder is a medium that plays a dispersing role in the ink and is one of the important components of the ink. As a binder in the ink, it must be a tacky liquid.
The binder is a dispersion medium in the ink, so that the pigment and the filler are evenly dispersed therein, and a protective shell is formed around them, so that the aggregate precipitation phenomenon does not occur and the ink has a good printing property.
31. What is the relationship between the printability of the ink and the binder?
Printing ink should have a vivid color