Analysis of relationship between carton strength and production factors (2)

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Relationship between production design, corrugated board characteristics and corrugated box strength

The shape of the box and the structure of the carton are different, and their compressive strength will be very different. The maximum supporting force of the carton should be: the four corners of the box and the sides next to the corners. It can be seen that the supporting force of the square carton is relatively larger. In addition, the longer the perimeter of the box, the higher the height, the lower the corresponding compressive strength; the larger the area of ​​the opening, the closer the compression resistance of the box closer to the corner is, so the design should pay attention to these conditions .

Corrugated type definition, characteristics in accordance with the provisions of GBT6544-1999 standard, UV-shaped corrugated cardboard is divided into A, C, B and E type four. The enthalpy height of A type is 4.5 to 5mm, the number of turns in units of 300mm is 32 to 36, the height of C type is 3.5 to 4mm, the number of turns in units of 300mm is 36 to 40, and the height of B is The number of turns is 2.5 to 3mm and 300mm in length, and the number of turns is 48 to 52. The height of an E-shape is 1.1 to 2mm, and the length of a 300mm length is 92 to 100. The A-type corrugated corrugation is high and wide, so it is called a large-scale type. The A-type carton bears poorer planar pressure performance than the B and C-types, but it has higher vertical pressure resistance, so it is more suitable for the production of cartons containing non-pressure-resistant items, and is more commonly used. The crucible height and the number of turns per unit length of the C-type carton, and its performance, are between the A and B types, and it is also known as the "fine" type, which is suitable for containing general items. B-type corrugated medium is low and dense, so its vertical pressure resistance is poor, but its flat pressure resistance is high. Therefore, B-type paper is suitable for bottled foods. E-type paperboard corrugated low and fine, it is also known as a small rake. E-type cardboard has the characteristics of light weight, good cushioning performance, good flat compressive strength, etc., which facilitates direct printing. The three types of corrugated paperboards A, C, and B can also be combined into double corrugated paperboards and three-watt corrugated paperboards to greatly increase the strength of the carton. Most non-pressure-resistant products such as cigarettes and glass containers are packaged in corrugated boxes with multi-layered structures that are resistant to pressure and impact.


Corrugated waveform characteristics

Corrugated waveform refers to the shape of the top and bottom of the corrugated top and its edge line. The corrugated board waveform has a certain influence on the compressive strength of the carton. Corrugated waveforms are U-shaped, V-shaped, and UV-shaped. The U-shaped ridges are arc-shaped. This type of corrugated cardboard has good cushioning and elasticity. The slight deformation of the corrugated ridges can be quickly restored and the cul-de-sac does not break easily. However, the pressure it receives is worse than that of V-shaped cardboard, and the amount of core paper and adhesive is large. The V-shaped ridges are triangular in shape, and the 楞-shape is composed of straight lines. The intersection of two straight lines constitutes 600. The V-shaped crucible carton has a small amount of core paper and adhesive, and has strong and durable good characteristics. Its plane compressive strength is significantly higher than that of a U-shaped crucible, but once it has been deformed under pressure, it cannot be easily restored to its original shape. UV-shaped helium is compatible with the advantages of V and U shape, making up for their own defects, able to withstand higher pressures, and greatly improving the strength of the carton.

The relationship between cardboard production process, equipment failure and corrugated box strength

The quality of corrugated board produced by single-sided machine has great influence on the strength of corrugated box. The quality of single-sided machine is mainly reflected in the hardness, flatness, adhesive strength and corrugating forming effect of the board. The production process shows that the strength of corrugated paperboard, and the quality of linerboard and corrugated paper are certainly influential factors, but if the production process is not properly controlled, even the best paper quality cannot produce high-strength corrugated cardboard. Comparing and analyzing experimental results, it was found that, sometimes with paper materials with high index values ​​such as quantitative and ring crush strength, the hardness of the corrugated paperboard produced was not as good as the corrugated paperboard made from paper with low quantitative and ring pressure index. ,There are:

Incorrect selection of paper and paper corrugated cardboard are made of cardboard and corrugated paper. If the moisture content between them is too large, then after the glue is absorbed and heated, the paper's expansion and contraction will also change. Obvious differences, it is easy to cause the cardboard curl, so that the strength of the carton. Therefore, before the paper roll on the machine, it is best to test the moisture content of the base paper, try to choose the box paper and corrugated paper with similar moisture content to match the production, in order to prevent the paper board from curling.

Machine Speed ​​Discomfort The speed of a single-sided machine is too fast or too slow, which will affect the stiffness and bond strength of the board. Especially when the moisture of the base paper is high, if the production speed of the machine is too fast, the warm-up time is short, and the time for “eating glue” on the corrugation peak is short, so that the bonding effect and forming hardness of the cardboard are reduced. If the speed of the machine is too slow, the heating time of the board is relatively long, the board will easily become brittle, and the overheated temperature will cause premature curing of the adhesive, affecting the adhesive effect, all of which will reduce the strength of the board. Therefore, the production speed of the machine should be based on the situation of the moisture content of the base paper, the preheating area and the temperature, comprehensive consideration, and reasonable control, in order to ensure the quality of corrugated board production. According to the experience of the production process, the machine speed can be mastered by referring to the following table:

Adhesion Poor Adhesive quality of cardboard directly affects the compressive strength of the carton. The bonding quality depends mainly on the properties of the binder and the operating process, such as the physical and chemical properties of the viscosity, pH, solid content, and gelatinization temperature of the binder, and the blending operation of the binder. In order to ensure the bonding strength of the cardboard, good raw and auxiliary materials must be used. According to the actual production conditions, adjust the ratio of the binder, control the mixing time, stir the binder evenly, and use good water quality as much as possible. In the production process, it is necessary to control the amount of rubber properly, grasp the relationship between the speed of the machine and steam pressure, temperature, and the amount of adhesive applied to prevent the occurrence of blistering, pseudoplastic, and degumming. Improve the strength of the cartons.

The machine parts are in bad condition When corrugated roller shaft heads and bearings are worn or damaged, causing corrugated roller looseness, poor parallelism, and damage to crucibles, etc., it is prone to flat boring, collapse, high and low blemishes, degumming, foaming And corrugated board thickness and other quality issues. In addition, the old single-sided machine, the guide sheet wear and dirt, and the gap with the corrugated roll is too large, it is easy to cause the corrugated paper to jump, resulting in poor adhesion and high and low defects. The existence of all these unpleasant phenomena will reduce the compressive strength of the carton. In this regard, the corresponding measures should be taken in accordance with the location where the malfunction occurs.

Corrugated Roll Sticky Impurities When sticking foreign objects on the corrugating roll groove, the corrugated cardboard will be deflected, raked, or collapsed. This will cause poor adhesion. At the same time, it will reduce the strength of the carton. In this regard, the debris of the corrugated roll grooving should be cleaned to better solve the problem.

Improper printing pressure adopts the production process of directly printing under the corrugated board. If the printing pressure is too heavy, it will easily damage the corrugated board. It affects the strength of the carton. Therefore, the preprinted corrugated board must grasp the appropriate printing pressure to ensure the compressive strength of the carton.

In summary, there are many factors affecting the carton strength index. The quality of raw materials, the status of production equipment, and the appropriateness of the production process control will affect the strength of the carton. Therefore, by properly understanding and understanding these conditions and carefully controlling raw materials and production processes, we can effectively improve the quality of cartons and meet the needs of customers.


Author: Kang Kai

Source: "Corrugated Paper Cases"

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