Corrugated paper is the main material for manufacturing various carton boxes and packaging. Its quality and strength will directly affect the effect of carton packaging. The requirements for the quality and strength of corrugated paper are firstly affected and limited by the production process and operation, and on the other hand the requirements of the product to be packaged and the use.
Sampling is the first step in accurate measurement of corrugated cardboard. Sampling should show the characteristics of this batch of cardboard to the greatest extent, but sampling should be as small as possible.
The humidity and temperature of the air have a great impact on the physical properties of paper and paperboard. Proper humidity conditioning is necessary before measurement (the north may require humidification, and the south may need to be dried. Different seasons The way is different).
The following introduces the strength index and test method of corrugated paper
1. Ring compression strength of corrugated cardboard and carton board
It is more difficult to determine the compressive strength perpendicular to the thickness of the paper. The usual practice is to surround the paper or cardboard in a ring shape and then apply pressure, which has much better shape stability. Therefore, surround the base paper or cardboard into a ring shape and measure its compressive strength. This is the ring compressive strength of the base paper or cardboard.
2. Flat compressive strength of corrugated core
The main function of the corrugated core is to keep the cardboard with a certain thickness when the corrugated cardboard is deformed under pressure, so that the cardboard gets a larger moment of inertia. The corrugated paper core should be able to withstand the effects of stress and strain, and form a uniform contoured corrugation at the time of high-speed corrugation, and can be firmly attached to the tissue paper.
This function of the corrugated core can be measured by the flat compression strength of the fluted corrugated core. The corrugated core's flat compressive strength is measured by first pressing the corrugated base paper at a certain temperature and pressure with a flute tester to form a certain shape of corrugation. Then do a flat pressure test on a small test machine to determine its load carrying capacity, which is expressed in KN (kgf).
3. Flat compressive strength of corrugated cardboard
One of the inherent characteristics of corrugated cardboard is its large moment of inertia. When the corrugated cardboard is subjected to large pressure inertia, maintaining its original thickness is a prerequisite for maintaining its characteristics.
The ability of corrugated cardboard to not be flattened when it is subjected to flattening pressure is an important strength indicator for detecting corrugated cardboard. This index is particularly important for the elasticity of corrugated cardboard in use and the various processes of making carton to maintain the original thickness of the cardboard.
Corrugated cardboard's flat pressing strength is expressed by the force acting on the unit area of the cardboard, and the unit is kPa. To measure the flat compressive strength of corrugated cardboard, a small pressure testing machine can be used to take round samples. The diameter of the sample is 5.13 cm.
4. Corrugated cardboard side compressive strength
Corrugated carton is different from paper bag in that it is applied as a rigid container, and it must maintain a certain shape during use. One of the main forms of corrugated box damage is crushing and loss of rigidity. The index that reflects the rigidity of the carton is the compressive strength of the carton, which is directly related to the side pressure strength of the corrugated cardboard.
The side pressure strength of corrugated paperboard refers to the ability of the paperboard to withstand compressive loads along the corrugated direction. It is expressed in force per unit length. The unit is N / m. This index can be used to compare production under similar conditions, but not in the same batch. The quality of the product; it can also be used to compare the side pressure strength of corrugated cardboard produced from different materials.
For measuring the side compressive strength, a special small-scale pressure testing machine can be used.
5. Breaking resistance
Bursting resistance has always been considered as an important quality index of corrugated cardboard and its components (core paper, face paper and backing paper). Simply put, it is how much force the board can withstand without breaking.
6. Penetration strength
Penetration strength can be used to measure the resistance of corrugated cardboard to damage caused by the impact of sharp objects. It is a comprehensive indicator. Recent studies have shown that the tear strength of the face paper in both the vertical and horizontal directions is related to the corrugated core paper, and the flat compression strength of the corrugated core paper has an important influence on the strength of the corrugated cardboard.
The puncture strength was measured with a puncture strength tester. The tester uses a pendulum equipped with a piercing head to determine the resistance of the cardboard to puncture by the change in the potential energy before and after the cardboard is pierced. The change in the potential energy is converted into kinetic energy to pierce and tear the cardboard. To indicate the puncture strength of paper or cardboard.
7. Adhesive strength
Adhesive strength refers to the bonding strength of corrugated paper to face or backing paper. Apply an outward pulling force perpendicular to the surface of the face paper or corrugated core paper until the two are separated. The maximum load that the interface of the adhesive or bonding fiber can withstand before separation is the adhesive strength of the sample, also called peel strength, and the unit is N.
The adhesive strength can be measured with a small pressure testing machine. The tensile force applied to the face paper and the corrugated core paper is generated by inserting the upper and lower sets of pins of the corrugated board, so the test is also called the pin adhesive strength test.