Analysis on the relationship between the strength

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Analysis of the relationship between carton strength and production factors (Part 1)

corrugated carton strength is an important technical index for the quality inspection of packaging containers. The level of these indexes reflects the quality of raw materials on the one hand, and the durability on the other hand also reflects the quality of processing technology. The production process shows that it is not enough to improve the strength of corrugated boxes only by purchasing good raw materials. Doing a good job in the quality control of the production process is also an important part of improving the strength of corrugated boxes. Therefore, a correct understanding and understanding of the relevant factors affecting the strength of corrugated boxes is of great significance for better production and improving product quality

technical index of base paper and its relationship with corrugated box strength

quantitative quantity is also called gram weight, which refers to the weight of paper per square meter, expressed in g/m2. The quantitative calculation formula is: sample weighing/sample area. Quantification is an important index to measure the physical properties of paper. Generally speaking, if the quantification of paper is high, its tensile strength, ring compression strength, tear strength, stiffness and thickness are relatively high. The compressive strength of corrugated boxes made of high quantitative paper is relatively higher. Therefore, to make corrugated boxes with high strength, it is often one of the basic requirements of customers to choose high quantity paper materials

tightness refers to the weight of paper per cubic centimeter, expressed in g/cm3. The calculation formula is:

tightness = quantitative/(thickness × 1000)

the tightness of paper reflects the density of its fiber structure. The tightness value of carton board paper and corrugated paper is high, and their burst resistance, ring compression strength, puncture resistance and tension resistance are relatively good, so the overall strength of the carton is relatively high. However, if the tightness is too large, the paper is prone to embrittlement, especially whiteboard. If the tightness value is significantly greater than the standard, its folding resistance will be reduced. Therefore, the corrugated board with white board as the surface layer should not use white board with too high tightness, so as not to affect the folding resistance of the carton flap

ring compression strength take 10 standard samples with a length (longitudinal) of 152 ± 0.2mm and a width of 12.7 ± 0.1mm for testing, of which 5 samples face outward for testing. The other five pieces are loaded into the annular tray with the reverse side facing outward for detection, and then the annular pressing strength of the base paper can be calculated through formula conversion. Generally speaking, cartons made of paper with good ring compression strength have relatively high strength. The calculation formula of ring compression strength is: RF/152. Where, R refers to the ring pressure strength, in kn/M; F is the force value read when the sample is crushed, in N; 152 is the length of the specimen, in mm. The standard value of the ring pressure index in the national standard is an important index to measure the compressive performance of the base paper. It refers to the ratio of the ring pressure strength of the base paper to the quantitative value, and the unit is n · M/g. The calculation formula of this index is: rd=1000r/w. In the formula, RD refers to the ring pressure index, R refers to the ring pressure strength, and W refers to the quantity of the sample, in g/m2. The ring pressure index of the base paper greatly affects the overall strength of the carton, especially the compressive strength of the carton

sizing degree during the production of paper and paperboard, a certain amount of rosin and other water-resistant colloids are applied to increase the water resistance of the paper surface. This production and processing process is called sizing. Sizing degree is a quality index to measure the size of sizing amount. According to national standards, ink scribing method and surface absorption gravimetric method can be used for detection. Factories can also use the "dripping method" to detect the sizing degree of paper. The method is: drop a little water on the paper. If the water drops leak fast, it indicates that the sizing degree is not good; If the water drops are not easy to leak, and the water drops float on the paper, it means that the sizing degree is good. The base paper for making corrugated boxes requires a good sizing degree, so it is not easy to absorb moisture in the direction of rare earth functional materials, and the moisture content of the carton is stable, which can better ensure the strength of the carton

moisture content the so-called moisture content refers to the moisture content in paper or paperboard, expressed in percentage. The calculation formula for its inspection is:

moisture content = (original weight of sample - weight after drying)/original weight of sample

moisture content has a great impact on the strength of carton box, which is 7.9 percentage points higher than the same period last year; The profit is 628.55 billion yuan, so this is also the main reason why moisture content has become one of the three important defect inspection items of cartons. When the moisture content of the carton is high, its puncture compressive strength and bursting strength will be relatively reduced. Corrugated paper has certain pressure resistance, tension resistance, puncture resistance and folding resistance. If the moisture content is too high, the paper will appear soft, with poor stiffness, and the quality of corrugated and bonding is also poor. If the moisture content is significantly lower than the lower limit standard value, cracking is easy to occur during crimping. If the moisture content of corrugated paper and carton board is too large, the corrugated board processed by one-sided machine is easy to curl, and foaming and degumming are easy to occur in the next process of lamination, which significantly reduces the strength of the carton

As a final packaging container, the folding carton needs to be opened frequently, which requires that the paper material should have a certain folding capacity. The transverse folding resistance of paper is to measure the bending resistance of 150 × 15mm sample is subject to 1350 angle reciprocating folding test. When the paper sample is broken, it is the number of folding resistance tests. The folding resistance of the base paper is largely determined by the size characteristics of the box paper and folded paper, the moisture content, tightness, fiber length and the fastness of the binding force of the paper, as well as the storage time and temperature of the base paper. Therefore, to improve the folding resistance of cartons, it is important to check the quality of raw materials

(to be continued)

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