The root cause of color box packaging is the same, except that the moisture content and the paper type are too low, and the weather is dry. Next, we will explain several practical solutions.
First, how can we ensure the moisture content of the color box packaging cardboard?
1. Ensure proper dryness during glazing. Generally speaking, a large-diameter exhaust duct is used and cooling water equipment is installed on the drying tunnel. This way, it can prevent the color cardboard from being too dry and the paper type becoming brittle during dry curing. Present.
2. Under normal circumstances, the moisture content of the cardboard after mounting colored cardboard can reach more than 10%. But when the weather is hot and dry and the moisture content of the cardboard to be mounted is very low, the moisture of the glue will quickly evaporate, and the moisture content of the mounted cardboard is still very low. At this moment, you may wish to use the wet water roller of the self-mounting machine to wet water on the reverse side of the cardboard. At the same time, use glue with low solid content and increase the amount of glue, so that the moisture content of the laminated cardboard can be enhanced in a short time. .
3. For the mounted colored cardboard, if the moisture content is too low, you can use a monochrome printer or a flexo to print water on the reverse side of the cardboard. After the water is printed, the cardboard should be tightly encapsulated with plastic film. Die cutting will not be carried out until the moisture of the cardboard is balanced the next day. Note that it is best to glue the box immediately after die-cutting. If it needs to be placed for a period of time and then glue the box, it is also necessary to use "stretch film" to encapsulate, so as to avoid premature loss of water and recurrence of old diseases. The choice is different according to different mounting pits and moisture. Coated white card with folding resistance, for most single-pit cardboard color box packaging, because the tensile strength of the flap is not high when it is folded, there are fewer burst lines. However, for high-strength corrugated paper and double-corrugated cardboard, it is not easy to solve it by adding moisture alone. For example, there is a color box packaging with 350g white card/150VISY/250g Liwen cattle card/150VISY/250 grams Liwen cattle Card. Since the material is excellent, and the surface layer coating is not allowed, it is also necessary to equip the whole wood pulp bovine bottom white card with better folding resistance.
Second, the test method of the folding resistance of the white card coating:
1. Cut five samples with a size of 250×50mm with a paper cutter (make sure that the straight grain direction of the paper is perpendicular to the long side), and store it for 4 hours at a temperature and humidity of 23±1°C and 52±2% .
2. Bend the sample inward so that the two short sides overlap, making sure that the middle part of the sample is arc-shaped.
3. Place the bent sample under a pressure roller weighing 10KG, press the overlapped end, and push the pressure roller to the middle arc of the sample, so that the rolled sample is folded in half.
4. After reciprocating rolling for many times, open the sample and check whether the surface layer of the rolled origami is cracked. If there is no other cracks, it means that the white card coating has good folding resistance; if there is a slight crack, the white card coating is generally resistant to folding; if there is obvious cracking, it means that the white card coating has poor folding resistance.
Third, some other minor improvement methods
1. Reasonably design the film-cutting plate, the high-quality indentation steel wire should have suitable hardness standards, strong reliability, round cutter head, arc-shaped central axis symmetrical graphics, small error of high degree and thickness, and complete specifications. The basic principle of the selection is: the thickness of the indented steel wire is not less than the thickness of the paper, and the height is equivalent to the height of the film cutting blade minus the thickness of the film cutting material, and then the correction value 0.05～0.10mm is subtracted. The basic principle of the selection of the indentation line is: the thickness of the indentation line is not less than the thickness of the paper, and the total width is equivalent to 1.5 times the thickness of the paper plus the thickness of the indentation steel wire.
For example: film cutting 0.40mm thick paper type, the height of the film cutter is 23.80mm, and the thickness of the indentation steel wire is selected as 0.71mm, then: the height of the indentation steel wire = 23.80-0.40-0.10 (0.05～ 0.10) = 23.30 (mm) the thickness of the indentation line ≥ 0.40 (mm) the total width of the indentation line = 0.40 × 1.5 + 0.71 = 1.31 (mm).
The opening of the connecting point is essentially to draw out some total width openings at the specific position of the cutting edge of the film, so that the carton and waste edges after film cutting will not be scattered, which is beneficial to waste discharge. The connecting point is usually located in a hidden place that is not easy to see after the product is formed, and at the same time, it is necessary to bypass the specific location of the glue line. If the connecting points can be seen after forming, the connecting points should be as low as possible. Otherwise, the connecting points are not easy to separate when the waste is discharged, which will cause the paper type to tear and the surrounding ink layer to burst. The total width of connecting points = paper thickness + 0.20mm.
2. When the distance between the indented steel wires is too small, it is necessary to paste the sponge rubber strip to have the effect of anti-tension to clamp the paper type tightly and relieve the pressure difference. In addition, the groove shape can be drawn out at the press line position when the board is leveled, so that the color box has a larger arc when folded and formed, which has the effect of alleviating the line burst.
3. If the user has no special requirements, and there is no white cardboard with stronger folding resistance, the packaging box manufacturer proposes to change the color paper to the laminating process, which can be done once and for all.