Boiled bags of material selection

BOPA/LDPE structure of water bag, a large number of applications in kimchi, bamboo packing. BOPA/LDPE boiled bags actually have higher technical index requirements, although there is a certain scale of soft package enterprises can make water bag, but the quality is uneven, some mass there will be more quality issues. In this paper, the BOPA/LDPE boiled in the process of bag making key points are analyzed. 1. BOPA film (1) the choice of arching phenomenon of the nylon membrane BOPA film production can use tube membrane tensile method, also can use the plane two-way stretching method of production. Different methods for production of two-way stretch nylon membrane have different arch effect, its printing overprint precision of thin film and bags ( Including cooking before and after boiled flour appearance) The flatness of has significant effect. Testing the nylon membrane arch effect of the specific method is to determine the heat shrinkage rate of the diagonal. National standard of thermal shrinkage test conditions, we can also according to the actual working conditions of water bag ( Such as 100 ℃ for 30 min) To detect damp heat shrinkage rate of nylon membrane, diagonal, the smaller the difference of thermal shrinkage rate show that the product of proportionality, the better. The difference is less than 1. When 5%, the bag won't produce newborn. (2) market supply varieties of BOPA film is divided into two printing and compound, printing, composite can be used in the printing process, composite level is only recommended for composite process without printing. 12 microns thickness is general, and 15 microns, 25 microns two specifications. 15 microns in flexible packaging composite membrane, 25 microns medicine for cold forming aluminum packaging. For the middle layer composite, and for water cooking purposes, be sure to use double corona films. (3) key BOPA film quality requirements and high flatness requirement should choose a small arch effect of synchronous stretch film. B, the surface tension of the film & ge; 50 mn/m, to ensure that the ink attachment fastness. Value is not the bigger the better. C, choice of relative humidity adaptability good film, to ensure accuracy. D, select heat shrinkage smaller film varieties ( Wet and heat shrinkage) 。 2. The choice of heat sealing layer PE boiled PE bag is different from ordinary PE: (1) a better heat sealing strength; (2) good heat sealing of inclusions; (3) good thermal adhesive strength ( When boiled not torn bags) ； (4) good thickness uniformity & rarr; The stability of heat sealing quality; (5) good transparency, no obvious water striate; 6. No effect to use the fisheye, impurities, and crystal & rarr; Appearance of bubble, even pierced PA membrane & rarr; Barrier property, or oil leakage phenomenon. Before three o 'clock when quality characteristics is mainly composed of blow molding PE film layers of aggregate formula. 3. Printing ink selection of nylon membrane generally choose special polyurethane ink: 1) there are no benzene ketone series; (2) no benzene ketone series. Note: when choosing printing ink (1) don't type of patient choice of color, such as a polyurethane ink F1200 red, red, F1150 1500, F2610 Jin Chi, F3700 orange, F4700 medium yellow color, such as other ink is not promoted in the prospectus for BOPA/PE structure of boiling film printing, some color is not water resistant, pigment leakage phenomenon is seen when the water is boiling. (2) to be cautious with gold and silver color. For gold and silver color, printing ink factory are not recommended for water use in the specification, but the water bags on the market some application of the gold and silver color, is common practice in the application before consulting the ink factory formula design, also note not big color piece of printing. (3) to the nylon membrane has good ink adhesion fastness, which ensures that ink parts the peel strength. 4. The choice of adhesive choice ability boiled, the adhesives and ensure the compound after crosslinking curing degree. In addition, Chen Jiao reuse should be careful when ( General should avoid to use) Because Chen Jiao glue solution in the process of placing the main agent and curing agent group effective ratio imbalance, easy to sub don't do it. 5. Ethyl acetate the quality requirements of the 'industrial ethyl acetate' specified in GB/T 3728-91, classy article moisture content is less than 1000 PPM, grade a moisture content is less than 2000 PPM, non-conforming material moisture content is less than 4000 PPM. Ethyl acetate in water and alcohol ( Not only is ethanol, methanol, isopropyl alcohol content also should control) Can react with the glue of curing agent and curing agent and consumption, sub not phenomenon, is the water bag is one of the main reasons for rubber wrinkle.