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What are the technical indicators of the paper

Edit:Zhongshan Yida Paper Co., Ltd.UpDate:2020-06-17

What are the technical indicators of the paper used by Niu Cardboard Wholesale? It is mainly for the technical indicators of printing paper to make a detailed description. The main technical indicators of the printing paper involved are quantitative, thickness, thickness, width, whiteness, opacity, Surface absorption, fracture length, lateral folding resistance, smoothness, lateral expansion and contraction rate, printing surface strength, ash content, dustiness, and moisture. The following cattle cardboard wholesalers will analyze an indicator:

1. Whiteness

For printing, the whiteness of cardboard paper directly affects the color effect of the product. Therefore, the whiteness of cardboard paper is one of the most important parameters in paper properties. The so-called whiteness, as the name implies, is the whiteness of the paper. It is the performance of the reflection ability of light waves in the full wavelength range. At present, our country mostly adopts the method of measuring the whiteness (brightness, also known as brightness) of paper to reflect the whiteness of paper. The whiteness is only measured by the reflection value of the paper to the light waves, and the visual characteristics of the eyes are not considered, because the visual whiteness is a physiological combination of purity and true whiteness. Due to the addition of fillers and dyes in the paper, the whiteness can no longer accurately reflect the visually acceptable whiteness. Nowadays, the whiteness of paper is often used internationally. Since the measurement of whiteness is based on the visual characteristics of the human eye, it can better reflect the whiteness of paper. If there are two sheets of paper, the measured whiteness of paper A is 70 degrees, while the whiteness of paper B is 68 degrees. In theory, paper A should be whiter than paper B, but it may happen that paper B looks even worse than paper A. To be whiter, this is because of the chemical substance Royal Blue added to the paper, Royal Blue can enhance the whiteness, but does not increase the whiteness. Paper with a higher degree of whiteness can reflect almost all of the light, making the color on the printed piece distinct. Whiteness For cultural paper, a certain degree of whiteness is required, but it does not mean that the higher the whiteness, the better. Paper with too high whiteness looks dazzling and affects people's vision.

2. Quantitative

The weight of paper per square meter, in g/mm. The basis weight must be uniform, otherwise the paper stack will tilt and bend and cannot be printed normally, and the uneven basis weight will directly affect the smoothness of the paper.

3. Thickness

The thickness of the cow cardboard paper sample between the measuring plates under a certain pressure.

4. Thickness and width difference

The difference in the thickness of the cardboard in the horizontal direction, if the value is too large, it means that the thickness of the paper is uneven, it may be discounted in the printing direction, and even the paper cannot pass the printing machine.

5. Tightness

The weight per cubic centimeter of paper. Increasing the tightness of the paper can enhance the tensile strength and burst resistance of the paper, but if the tightness is too large, the opacity of the paper will decrease, and the bulk of the paper will be poor, the hand feel is poor, and the compressibility of the paper will be low. it is good. Because the thickness of the paper is not necessarily uniform, and the pressure of the printing plate in contact with the paper during printing is light or heavy, it will inevitably affect the printing quality. Any print printed on a soft, flexible, and compressible paper. It must be clear and distinct.

6. Opacity

Opacity is the ratio of the reflectivity of a single sample on the "fully absorbing" ink pad to the reflectivity of several samples that are completely opaque, and represents the opacity of the paper. Generally speaking, it is the degree of paper penetration. For cattle cardboard wholesalers, it is necessary to not see through, the ink on one side does not penetrate to the other side to ensure the quality of printing, otherwise it will affect the clarity of the handwriting or pictorial on the other side. A certain degree of opacity is also required for writing paper to facilitate writing on both sides of the paper. Opacity For printing paper and writing paper, the higher the opacity, the better.

7. Surface absorption

It refers to the ability to absorb water or other liquids. The surface absorption should have a certain amount to facilitate the transfer and absorption of the ink. If it is too large, the water absorption will be too large and the paper will be easily deformed during printing.

8. Crack length

The length of the cardboard or cardboard when it breaks due to its own weight, which indicates the ability of the paper to resist tensile breaking. This index is very important for paper for rotary printing, because the higher break length helps to withstand the traction of the printing press.

9. Transverse folding resistance

Refers to the number of reciprocating folds that the paper can withstand 180 degrees under a certain tension. Since the book has to be read many times, the paper must have a certain degree of folding resistance to prevent premature damage to the book.

10. Smoothness

The smoothness of the paper jam refers to the smoothness and flatness of the paper surface. It is more important for printing paper. The essence of printing is the transfer of ink to the paper surface. The better the ink film is in contact with the paper, that is, the flatter the paper, the smoother the printed matter can be printed. The surface can absorb ink evenly. The lines of the prints and drawings printed on the smooth printing paper are relatively clear and eye-catching. The smoothness of the paper often affects the quality of printing. Paper with rough surface is difficult to get ideal imprints, so high-end coated paper must be used for fine printing products to ensure the printing effect.

11. Lateral expansion rate

It refers to the relative change of humidification or dehumidification size when immersed in water or under different humidity, expressed by the increase or decrease of size. It can indicate the dimensional stability of the paper, whether the paper size is stable, it is very important for the color offset printing, the paper is required to not stretch as much as possible, or the stretchability is not large, and the paper with poor dimensional stability is easy to deform when printing. Poor registration during offset printing can easily lead to inaccurate registration.

12. Printing surface strength

Also known as napping speed, it refers to the bonding strength between fibers, fillers, and sizing materials, and reflects the ability of paper to resist lint and powder under certain pressure. It is determined by the papermaking raw materials and technology, the choice of filler and the degree of calendering. The surface strength of paper is an important indicator of printing paper. Paper with insufficient surface strength is prone to shed hair and powder during the printing process. The phenomenon of lint and powder is also related to ink viscosity, printing pressure and printing speed.

13. Ash

The ratio of the weight of the ash after burning the paper sample to the weight of the original absolute dry sample. Generally speaking, the greater the ash content, the more fillers, and the fillers are too large. If the dispersion is uniform, it is fine. If the dispersion is not uniform, it is easy to cause local powder loss.

14. Dust degree

Refers to the fiber bundles and other impurities that are exposed to the paper surface and can be seen at any angle of irradiation and the color of the paper surface is significantly different, expressed by the number of dust degrees per square area of ​​the sample within the specified range . It directly affects the appearance quality of the paper.

15. Moisture

Refers to the ratio of the weight of moisture contained in a certain weight of paper to the total weight of the paper, expressed as a percentage. The moisture of the paper changes with the temperature and humidity of the environment. The moisture we generally refer to refers to the moisture of the machine just off the machine. In actual application, the moisture of the paper should be balanced with the relative humidity of the printing workshop.

16. Sizing degree

Refers to the strength of the paper's water absorption, that is, the degree to which water penetrates and diffuses on the paper surface, and indicates the size of the water resistance. Different printing methods have different requirements on the sizing degree of the paper. For example, the sizing degree of offset printing paper is 0.75. The amount of sizing degree is determined by the standard ink marking method.

The above is an introduction to what paper technical indicators are available in NiuJia. Friends who are interested in NiuJia are welcome to consult us at any time!