Physical and mechanical properties of packaging paper and cardboard
Static strength is the strength measured under slow conditions, such as tensile strength, burst resistance, fold resistance and tear resistance.
Dynamic strength is the strength that reflects the dynamic condition of paper and paperboard that is instantaneously diffused and ruptured after being stressed, such as the air permeability, elongation, and rupture work of the paper bag paper of the packaging box;
Tensile strength: It means the maximum load when the paper will not break under the drawing of vertical gravity.
Burst resistance: indicates the maximum pressure that the paper can bear when it is subjected to vertical pressure without breaking
Tearness: indicates the strength of paper and paper against being torn, and its size is expressed by the force required to be torn
Folding resistance: indicates the ability of paper and cardboard to withstand folding. It is expressed by the number of times required to fold to break. The folding resistance of paper is generally greater in the longitudinal direction than in the transverse direction.
Air Permeability: It indicates the degree of voids in the packaging paper. It is an important indicator for determining the moisture resistance of paper and cardboard.
Absorption performance includes sizing degree (namely liquid increasing performance), water absorption performance, ink absorption performance, oil absorption performance, etc. Most papers have been sizing treatment to achieve a certain degree of liquid increasing performance. Papers that require liquid or oil absorption properties (such as filter paper, parchment base paper, impregnated processing base paper, etc.) are generally not sized. The absorption performance can be determined by chemical or physical methods. .
Paper packaging mostly requires printing decoration and logos. No matter which printing method is used, paper and paper are required to have good ink absorption, printing smoothness, surface uniformity, compressibility, opacity, Dimensional stability, surface strength and water resistance, etc.
Surface properties include smoothness, anti-wear properties, lint properties, adhesion properties, corrugated properties, roughness, etc. These properties have a very important impact on the implementation of paper packaging, and they must be measured with special instruments .
Chemical properties mainly refer to the chemical composition of paper and paper, the content of moisture and ash, the content of various chemical additives, acid value, viscosity and pH value, etc.
Anti-rust paper must not contain free acid, chlorine or alkaline substances;
Electrical paper, resin impregnated paper, food packaging paper, etc. must not contain toxic substances, have a proper pH value, and have a proper acid value and filler content.
[Optical and Electrical Properties]
The optical properties of paper include whiteness (whiteness), opacity, gloss and color.
The gloss performance of paper depends on the relative amount of light projected on the paper surface and the reflection, transmission and absorption of the projected light waves by the paper.
Electrical paper and or cardboard must have electrical properties that meet the requirements of use. It largely depends on the physical properties of the paper in the packaging box. This performance is mainly reflected in the electrical insulation or the cardboard must have a larger dielectric constant, higher dielectric strength, lower dielectric loss and higher The service life and heat resistance, etc.