Chemical composition of kraft paper tape!

Kraft paper is a kraft paper made from Kraft softwood pulp, which is beaten and copied on a long web paper machine. In fact, kraft paper and ordinary paper manufacturing methods are not much different. Kraft paper is stronger than ordinary paper.
This is mainly because the wood fiber used in kraft paper is longer than ordinary paper, and when cooking wood, it is treated with caustic soda and alkali sulfide chemicals, so that their chemical effect is more moderate, and the damage to the original strength of wood fiber is smaller.
Therefore, the paper made of this paper pulp is closely related to the fiber Yes, so kraft paper is very strong.

 

Chemical composition of raw materials

 

Plant fiber mainly contains:

 

1. Cellulose

 

Wood contains 40 ~ 50% cellulose. From the point of view of papermaking, we should try our best to preserve cellulose in the process of pulping in order to improve pulp yield and paper strength.

 

2. Hemicellulose is only about 20% in coniferous wood. In order to improve the pulping yield and paper strength, some hemicellulose should be preserved as much as possible in the pulping process.

 

3. Lignin

 

In coniferous wood, the lignin content is about 30%. Chemical pulping is the use of chemicals to dissolve a part of the binding material between cells, so that fibers are separated from each other into pulp. The more lignin in the raw material, the more difficult the pulping is, and the more chemicals will be consumed.

 

Minor components:

 

In addition to cellulose, hemicellulose and lignin, there are other components with less content, such as resin and ash. In the common raw materials, the content is not large, and it will not be too difficult for papermaking. However, if the content is too much, it is necessary to take corresponding measures to remove some paper with special request.

 

1. Resin, fat

 

The content of common raw materials is less than 1%, but it is more in pine wood. Their viscosity is large and they are easy to bond into a group. For example, it is difficult to make paper by sticking to copper mesh and pressing roller, and transparent resin spots are formed on paper, which reduces the quality of paper. They are easy to react with alkali to form soap and dissolve in water, so pine with more resin is usually pulped with alkali method to reduce their harm. Fat is generally harmless and can also be saponified and dissolved.

 

2. Starch, pectin

 

Starch is a kind of storage material in the cell cavity, which is easy to dissolve in hot water and has no effect on pulp and paper making. The pectin in common raw materials is not much, they are easy to be synthesized and dissolved by dilute alkali solution. It exists in the form of pectinate in plants and is thought to be the source of ash in plants. The medium of bast fiber such as flax is mainly pectin, which only needs a little alkali cooking to degumme.

 

3. Tannins, pigments

 

Ordinary raw materials are less harmful, they are easy to be extracted by hot water. However, if the content is large, it should be extracted in advance, otherwise, the color of the pulp will not be bleached easily.

 

4. Ash content

 

Ash is the inorganic salt in the raw material of plant fiber, mainly the salt of potassium, sodium, calcium, magnesium, sulfur, phosphorus and silicon. The ash content of wood is between 0.2% and 1.0%.

 

Used as packing information. Very strong. It is usually yellowish brown. Semi or full bleached kraft pulp is light brown, cream or white. Quantitative 80-120G / m2. The fracture length is generally more than 6000 M. The tearing strength, breaking work and dynamic strength are very high. Most of them are web paper, but also flat paper. It can be used as cement bag paper, envelope paper, adhesive seal paper, asphalt paper, cable protection paper, insulation paper, etc.