Plastic Package Printing and Compounding Technology Q&A (1)

1. What is the gravure dry composite unit gravure printing dry composite unit, which refers to the series compound. It is a continuous, automated new process in which the three processes of printing, extrusion compounding and extrusion coating are connected in series. There are also a series of gravure printing machines, dry laminating machines, slitting machines and bag making machines.
In the 1980s, various regions successively introduced wide-format (800 to 1200mm) disaggregated plastic printing composite units. These units were from different countries and regions, of which Japan was the most. For example, some have introduced the six-color gravure web transfer machine of Toshiba Machine Co., Ltd. of Japan. The dry-type compounding machine of Hirano Machine Co., Ltd., the slitting machine of Nishimura Co., Ltd., and the bag-making machine of TOTANI Co., Ltd. form a series. In addition, Japan's Continuous Vacuum Forming Machine was selected as another system. These lines can produce the most upscale cooking bags. Can be made of 2 to 7 layers of composite materials, can overprint six colors at a time, can maintain the quality and shape of the packaged products for a long time. This unit is best suited for the production of wide-format, high-volume printed composite products. At present, domestic printing machinery and equipment manufacturers are also piloting such complete sets of equipment.
2. What is a flexographic printing compound unit?
Flexographic printing compounding unit, it is the flexographic printing machine and multi-purpose coating machine, compound machine in series, composed of assembly lines, in order to improve production efficiency.
3. What primers are used for plastic extrusion?
The types and brands of primers used in extrusion compounding can be divided into two categories: aqueous and solvent. The aqueous type includes polyethyleneimine, and the solvent type includes alkyl titanium and isocyanate. The topping agent produced by Japan Toyo Ink Co., Ltd. is EL-250,420 and so on.
The EL-250 is used as a composite of PT, PET, OPP, CPP and LDPP. It is a solvent-type primer and is generally used for packaging materials with large moisture content and high pseudo-materials for composite strength.
When used ratio:
EL—250 15 (parts)
Ethyl acetate 100 to 85 (parts)
EL-250AT curing agent 1.5 (parts)
The amount of glue applied is generally 2kg/500m2 in terms of moisture content.
EL-420, used as PT, OPP and LDPP compound. It is an aqueous primer. It is generally used for materials that contain no water and have low composite strength requirements.
Proportioning when used:
EL-420 5% 0.5kg
Methanol 65% 6.5kg
Water 30% 3.0kg
Compound speed is 40m/min
EL-420 5% 0.5kg
Formic acid 95% 9.5kg
The compounding speed of the above ratio is 60-80m/min
The coating amount is 0.2-0.5 g/m2 (solid content).
4. What is hot melt compounding?
In the hot melt compounding method, polyethylene-acrylic ester copolymer, ethylene-vinyl acetate copolymer and stone vinegar are heated and melted together, and then coated on a substrate and immediately combined with other composite materials to be cooled and formed. Its advantages are short compounding time, no solvent pollution problems, and low cost. The disadvantage is poor heat resistance and transparency.
5, what is the wax compound method?
Wax compound method. The hygienic microcrystalline wax is used as a binder. The paraffin is placed in a heating tank and heated by an electric heater to melt into a molten state. When the web passes through the wrong phase, it is coated with paraffin and passed through a pressure roller. Two or more layers of base materials are compounded together. Such as paper and aluminum foil, paper and paper.
6. What is a multi-layer coextrusion compounding method?
The multi-layer co-extrusion compounding method is to compound a variety of different properties of plastic resin into a mold by multiple co-extrusion machines. Multi-layer coextrusion compounding is an advanced plastics processing technology in the 1980s. It has the following advantages:
(1) Simple processing technology, high processing precision, flexible structure change, energy saving, and low cost (2) No adhesive is used between multi-layer co-extruded composite plastic layers and layers, so there is no residual organic solvent The film has no odor and no harmful solvent penetration. Suitable for packaging of food packaging and medical devices.
(3) When multi-layer co-extrusion compounding, different properties of plastics can be selected to make full use of the good performance of various plastics, so that the composite film has moisture, moisture, gas barrier, water, oil, solvent resistance And heat sealing performance.
7, how to choose paper plastic film adhesive?
The type of adhesive used for film coating is solvent type, alcohol type, water soluble type, and water type. Variety, performance differences. Paper-plastic compound generally used solvent type: 1) EVA (ethylene, vinyl acetate copolymer resin) is a random copolymer, hot-melt adhesive E agent. 2) Solvent type acrylic adhesive. 3) Alcohol soluble acrylic adhesive. 4) Aqueous two-component polyurethane adhesive.
Because the production process of film-covered adhesive is not complicated, the raw materials are easy to purchase, the market is quite large, there are many manufacturers, and the performance is very different. It is advisable to purchase from the big manufacturers with advanced detection methods, strong technical strength, and large quality stability coefficient.
8. After the gravure printing and plastic printing after printing, what are the characteristics of the two paper-plastic composite methods?
"Paper-plastic composite" or "plastic-paper composite" is an inevitable trend of development. After the paper is printed by a four-color offset press, a thin transparent plastic film is applied by the laminator to achieve the purposes of moisture resistance, abrasion resistance, and gloss enhancement. The biggest advantage of the laminating machine is that it can be sheet-fed and it can be matched with the offset printing press; and the investment is small and the operation is convenient. It is more practical for the color printing factory, which is mainly printing paper. However, in terms of printing technology, the quality of BOPP gravure printing is less than that of BOPP gravitational change, printing ink gloss, color uniformity, and color saturation. In terms of composite quality, the dry laminating machine is superior to the laminating film in coating uniformity, composite fastness, and transparency. However, imported gravure machines and dry laminating machines and their supporting equipments have large investments and high costs. From this point of view, the flat printing foil has certain advantages.
9. What is the process of dry paper-plastic composite?
When using a dry laminator (laminator) for paper-plastic compounding, first use a biaxially-oriented stretched polyolefin film as the first substrate with a combined gravure web transfer machine; use 60 g or more coated paper, coated paper, etc. The tube was used as the second substrate; it was coated with a two-liquid polyurethane adhesive. The process flow is as follows:
The first unwinding base material - strong control - corona treatment - coating roller coating - drying in the drying tunnel - composite heating with composite roller - cooling - rolling - up - curing
(second unwinding substrate web)
Process parameters: first unwinding tension 4kg; second unwinding tension 5kg; winding tension 5kg; surface corona treatment tension 38-40 dyne/cm; drying path drying temperature should be ladder-shaped, temperature can be divided into three Segments: 1 segment 50 to 55 degrees Celsius, 2 segments 60 to 65 degrees Celsius, 3 segments 70 to 75 degrees Celsius, and no more than 80 degrees Celsius. The nozzle speed should be in the range of 20 to 50 m/min and a vortex formed on the substrate to be reconstituted so that the released gas stream can absorb the solvent evenly.
Paper-plastic composite, using two-component polyurethane adhesive, the best composite fastness. Polyurethane adhesives are short for polyurethane adhesives. It is commonly known as "Ulidan." Bicomponent means that the adhesive is divided into two groups: A and B. The A group is the main glue, and the B group is the curing agent (crosslinking agent). Component A consists of polycondensation of dihydric alcohols and dibasic acids. Polyester prepolymers with hydroxyl (—OH) groups as the end groups are used. Because they are modified with tolylene diisocyanate, they are still terminated with hydroxyl groups. However, the molecular weight of the compound is greatly increased. Then, the main polyurethane adhesive having a viscosity of 500 to 2000 centipoise and a solid content of about 35% was diluted with ethyl acetate. Group B consists of an addition reaction of trimethylolpropane and toluene diisocyanate with a viscosity of 1000-4000 cps and a solids content of 75%. Its characteristics are solid content of about 25%, high-speed coating amount of 3-5 g / square meter, its viscosity is suitable for more than 100m/min. When using the two-component polyurethane adhesive, the dilution ratio is: main agent: curing agent=100:15, acetate diester 116.
When the first and second substrates are combined, the compounding temperature should be controlled at about 70 degrees Celsius, and the pressure of the composite rubber roller should be the same, otherwise the composite material will appear wrinkle.
After compound cooling, the chill roll temperature is controlled between 20 and 30 degrees Celsius. The temperature is too high will produce "color roll" phenomenon, too low will reduce the adhesive performance.
After cooling and rewinding, the composite material is preferably placed in a curing chamber and aged at 50 to 60 degrees Celsius for 48 hours. The peel strength can reach 1 N/15 mm.
(If single-component polyene adhesives are used, dilution ratio: raw rubber: ethyl acetate = 1:16, other compound working conditions are the same as before).
10. What are the quality requirements for adhesives for paper-plastic composites?
The quality requirements of binders for paper-plastic composites: (1) Light color, good transparency, no precipitation, no impurities; (2) Good dispersibility and leveling property, not easy to generate bubbles, streaks, good drying, activation period Long; (3) not anti-yellowing, good light resistance; (4) non-toxic, non-irritating odor, less environmental pollution. (5) Good affinity for plastics and other films and papers, high peel strength, strong mucous membrane, superior in tension, oil resistance, acid resistance, etc.
11. What specific issues should be paid attention to when preparing paper-plastic compounding two-component polyurethane binder? How to grasp the amount of coating?
Paper-plastic composite two-component polyurethane adhesive, standard ratio: the ratio of the main agent and the curing agent can be blended with 100:10 to 15 weight ratio, and then diluted with ethyl acetate to a solid content of 15-25%. Can be glued and compounded. How to use: Dilution, add the ethyl acetate solvent to the main agent, stir, and then add curing agent to stir. Viscosity: Each time the glue is used, the viscosity cup should be used to determine the degree of glue according to the length of the baking path of the compound machine. When coating: how much the amount of coating is needed to control the quality of the 51, paper-plastic composite, coating roller pattern below 150 mesh, coating amount of 0.2-0.5 g / square meter (dry weight). Ethyl acetate in the adhesive must be fully evaporated in the drying tunnel, so the drying tunnel must have a certain length. In principle, it is appropriate to have the substrate run in the drying tunnel for 6 seconds.
If the amount of coating is too high, the surface may easily produce an "orange peel" phenomenon. When the amount of coating is too small, the adhesion between the paper and the plastic film is reduced. In practical work, the amount of adhesive applied should be based on the smoothness of the paper, the area of ​​the printed graphic ink, and the printing process. In general, the paper has high smoothness, tight fibers, and a small amount of coating. On the contrary, the paper has low smoothness, loose fibers, and the amount of coating should be slightly larger. Offset products have a smaller amount of glue, and embossed products have a larger amount of glue, and gravure products have a glue spread between the two.
12. What other methods can be used in addition to laminating and dry laminating machines in paper-plastic composites?
In addition to the compounding of the wax coating machine and the dry laminating machine, the paper-plastic composite can also use the extrusion compounding method, the wax compounding method and the wet compounding method. See Tables 1, 2, and 3 below.
1. Extrusion paper and plastic composites, uses and printing