Flexibility test method

Folding resistance test (GB/T2679.5-2002 "Determination of breaking resistance of paper and paperboard" )

The folding endurance is the logarithm (base 10 ) of the number of double folds required for reciprocating folding to a break under a certain standard condition. The folding endurance is the index of the paper's resistance to folding fatigue. The folding endurance is one of the basic mechanical properties of the paper and is used to indicate the ability of the paper to resist reciprocating folding. The fold resistance of paper is the number of folds required to measure the number of folds that a paper undergoes when it is stretched by a certain force and then folded back and forth to break it. It is represented by the number of times, and the unit is bi-folded. Degree, the result of the horizontal cut test is the transverse folding resistance. In general, the longitudinal folding resistance is higher than the transverse folding resistance, which is due to the arrangement of the fibers and the large binding force of the longitudinal fibers.

    What are the factors that affect the degree of paper folding? The degree of folding resistance of the paper depends on the length, strength, flexibility and binding force between the fibers of the paper used for papermaking. The long, strong, and well-bonded fiber paper has a higher degree of folding resistance; When the hardwood pulp or grass pulp is added in the softwood pulp, the folding endurance is significantly reduced. In addition, the paper's quantification, thickness, tightness, and moisture content have a large impact on the degree of folding. In the same kind of paper made from the same kind of pulp, in a certain range, when the thickness and basis weight are increased, the folding endurance will be obviously decreased; adding mineral filler in the fiber material can increase the tightness, but it will greatly reduce the folding endurance of the paper. When the moisture content of the paper increases, the strength of the paper will increase, while the paper with lower strength will decrease.

Conventional folding device, there are two, one for the horizontal, called Schopper (a Schopper) formula, when working near the sample reciprocating folded 180 degrees; the other is vertical, called M1T In the formula, the reciprocating bending angle of the sample is 135 degrees during operation.

Testing equipment: HD-519A MIT folding tester   

Bend angle: 135°±2°

Folding speed ; 175 ± 10 times /min

The width of the folding head : 19±1mm

Arc radius of the mouth : 0.38±0.02mm

Folding head distance : max 1.0mm

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