Corrugated carton is a commonly used packaging container, widely used in the outer packaging of goods, it plays a protective role in the storage and handling of goods. The characteristics of the use of carton products require that it must have certain solid and durable basic use requirements. To achieve such requirements, the corrugated carton material must be inspected so that the corrugated carton production process can be effectively controlled. Therefore, it is of great significance to correctly understand and understand the detection items and detection methods of corrugated box materials.
1 moisture content
The so-called moisture content refers to the content of water in the base paper or paperboard, expressed as a percentage. The moisture content standard of carton base paper varies with different paper grades. The corrugated paper standard is: A grade 8.0±2.0%; B grade 8.0±3.0,-2.0%; C, Grade D 9.0+3.0,-2.0%; Containerboard Standard: Grade A 8.0±2.0%; Grade B 9.0±2.0%; Grade C 11,0± 2.0%; D, E grade 11.0±3.0%; corrugated box moisture content standard: 12±4%. The moisture content has a great influence on the strength of the carton box. Therefore, this is also the main reason why the moisture content has become one of the three heavy defects inspection items for the carton. Measuring the moisture content of the base paper or carton, a more accurate detection method is to use the drying method, that is, take several samples from different parts, use a balance to weigh about 50g of the sample, and tear it into pieces and put it into the oven. Dry to constant weight, you can find the moisture content. The formula for calculating the moisture content is:
Moisture content = (original weight of sample - weight of sample dried) åŽŸæ¥ original weight of sample
Corrugated paper has certain pressure resistance, tensile resistance, anti-jamming and folding resistance. If the moisture content is too high, the paper will appear soft, and the stiffness will be poor, and the pressure and adhesion quality will be poor. If the moisture content is significantly lower than the lower limit standard value, the paper will be too brittle, cracking will occur easily when pressing, and the folding endurance is also poor. If the moisture content of corrugated paper and liner board is greatly different, the corrugated board machined by one-sided machining tends to be curled. When the lower twisting process is performed, blistering and degumming are likely to occur and the strength of the carton is significantly reduced.
Thickness of 2 corrugated cardboard
The thickness of the cardboard is also one of the inspection items for carton appearance defects. How the cardboard thickness index directly affects the paperboard edge pressure strength, puncture strength and compressive strength and other properties, and there are many reasons for the impact of the paperboard thickness index, such as the corrugated roll tip (top) parts become lower wear, guide The paper is not adjusted well, the speed of the single-sided machine is too fast, the external pressure is too high, and the temperature of the corrugating roller is low. If the thickness of the corrugated cardboard is relatively thin, its side pressure strength, puncture strength, and compressive strength will also decrease accordingly. The corrugated cardboard has different types of enamel and the thickness varies.
Corrugated board thickness refers to the vertical distance between the upper and lower sides of the corrugated board under a certain pressure. The laboratory usually uses the thickness of the corrugated board to check the thickness of the board. When measuring, select some parts of the board that are not damaged, indented, or uncovered. (Not less than 50mm from the edge) As a detection point, the measurement head is placed between the measuring head and the measuring anvil, and the readings of the dial indicator are read. The number of samples is generally 10, and finally, the average value is the test result. The thickness of the cardboard is large, and the vertical pressure resistance and flat pressure resistance of the carton are correspondingly high. Therefore, the thickness index of corrugated board is a test item that cannot be ignored in the production process.
3 side pressure strength
For a specimen of a certain width, the pressure per unit length can be called the side pressure strength. It refers to the ability to withstand the pressure in the direction parallel to the corrugation. In accordance with the relevant standards, specimens with side-pressure strength are cut from three rod boxes, each of which has three mechanically indented, non-printed and damaged specimens. The direction of the corrugations of the specimens should be the short side. Specifications 25mm x 100mm, error ± 0.5mm. This requires that the knife edge of the sampler should be kept absolutely sharp, and the blade on the knife holder should be installed in a proper position. The angle between the knife edge and the sipe can be adjusted to 45°. In addition, the tool tip can not be rubbed to the bottom of the sipe to prevent the blade from bending and deforming, so that the corrugated edge of the cut sample is prone to damage and fluffing, which affects the accuracy of detection. The conversion formula for side pressure intensity is: R=F/L+x103. In the formula: R is the compressive strength of the edge of the corrugated cardboard sample, expressed in N/m: F is the force value read when the sample is crushed; L is the length of the long side of the sample, and the unit is mm. The ring paper strength of the base paper and the adhesive strength of the paperboard largely determine the edge pressure strength of the paperboard.
4 Bonding strength
The peak adhesion of corrugated board paper, liner, core paper and corrugated corrugated paper, the maximum peel force that can withstand the test within a certain unit length, is called the adhesive strength of corrugated cardboard. The adhesive strength test is mainly used to test the fastness of the corrugated board, and the A-type corrugated board is tested. The pin thickness of the peeling frame should be 3mm, and the corrugated L of the B and C type corrugated board should be thinner. The pin should use 12mm more appropriate. Each pin on the stripping frame should be exactly aligned with the center of the corrugated notch. After equalizing the spacing, tighten each of the screws. Adhesion strength of the test sample, requires to take 12 pieces, that is, from each of the 3 sample boxes were taken 4 pieces, the corrugated direction is the short side (ie 25mm), the material is intact, no degumming, no foaming Piece. Sample size is 25mm x 80mm, error ± 1.0mm, which can better ensure the accuracy of the test. The conversion formula for bond strength is: PF/L. In the formula: P is the adhesive strength of the corrugated cardboard sample, expressed in N/m; F is the force value read when the sample is separated, the unit is N; L is the size of the long side of the sample and the unit is m. The quality of the adhesive, the formulation, and the suitability of the equipment and operating process determine the adhesive strength of the paperboard, and the adhesive strength of the paperboard will affect the carton's resistance to pressure and strength to a large extent. Break strength and puncture strength and other properties.
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