What is Wood Paper Pulp?
Paper pulp is processed and manufactured from wood pulp paper plants as raw material, and it is basic raw material for paper and pulp production. The raw material plants for pulping can be usually divided into four categories: stem fiber, bast fiber, hull fiber and wood fiber. Especially wood fiber is the most important one. The current wood resources cannot meet the development needs of wood pulp manufacturing process all over the world. In order to make up for the lack of raw materials, China has to import a considerable amount of pulp from abroad every year.
The Papermaking Pulping Process Flow
Pulping refers to the production process that uses chemical methods, mechanical methods or the combination of two methods to make the plant fiber materials dissociate into unbleached or bleached pulp.
The Category and Application of Paper Pulping Process
Mechanical wood pulp
Mechanical wood pulp is also known as ground wood pulp. It is the paper pulp made from the fiber raw materials by mechanical grinding method, occupying an important position in the papermaking industry. It has the advantages of low cost, simple paper and pulp production process, strong ink absorption, high opacity and soft and smooth. So it is suitable for printing. But because of shorter fiber, higher non-cellulose components content, so the paper strength is lower.
In addition, because the most of lignin and other non-cellulose are not removed, the products of paper get easily yellowed and brittle and are not suitable for keeping long-term preservation. Mechanical pulp usually refers to white or brown mechanical wood pulps. The white mechanical wood pulp is mainly for newsprint paper, also can be added other paper pulps for producing copy writing and printing paper. The brown mechanical wood pulp is used for the production of wood pulp paper, packaging paper and paperboard, especially for industrial paperboard.
Sulphate wood pulp
Sulphate wood pulp adopts the mixture of sodium hydroxide and sodium sulfide as cooking agent. During the pulp cooking processing, because the liquid effect is less, the fiber is without strong erosion. Thus, the paper and pulp production has the characteristics of strong strength, good folding endurance, good breaking resistance and tearing strength. It can be divided into the bleached type and unbleached type. The unbleached sulphate wood pulp can be used for making wood pulp paper such as kraft paper, bag paper, kraft paperboard and general packaging paper and paperboard. The bleached sulphate wood pulp can be used for wood pulp paper such as the high-grade printing paper, drawing paper, offset paper and writing paper.
Sulfite wood pulp
Sulfite wood pulp adopts the mixed liquor of sulfurous acid and acid sulfite as the cooking agent. The pulp fiber is long and soft, has the properties of good toughness, high strength, easy bleaching and excellent felt ability. According to the refinement, it can be divided into the unbleached type, the half bleached type and the bleached type. Because containing a small amount of lignin and colored impurities, so the unbleached pulp is yellow with hard fiber. It can be used mostly for medium printing paper, thin packaging paper, translucent paper and greaseproof paper. The half bleached pulp contains a lot of pentosan, so it can be used for transparent tracing paper and parchment. The bleached pulp is with white fiber and soft texture, however, after being bleached, its fiber strength is lower than that of the unbleached pulp. The pulp is mostly used for making all kinds of advanced papers.
Waste paper pulp
Waste paper pulp is made by using the used waste paper or the trimming paper cut by the printing plants as raw material after mixing of mechanical stress and bleaching or deinking processing. The fiber strength and performance of waste paper pulp is decided by the pulp type of waste paper. However, due to the fiber is destroyed again by liquid erosion or mechanical stress, the property is poor compared with the original fiber. According to the quality of the paper pulp of raw waste paper, it can be used to make printing paper, writing paper, paperboard low-grade paper.
(Maybe you want to see Waste Paper Pulp Production Line)
In addition to the above described several types of paper and pulp production, straw pulp, reed pulp, bagasse pulp, bamboo pulp, cotton pulp, hemp pulp and synthetic pulp are also included during the paper pulping process.
Pulp Manufacturing Composition
The fiber is mainly composed of cellulose in pulp as well as different degrees of hemi-cellulose, lignin, resin, pigment, pectin, ash and other substances. Of them, the cellulose and hemi-cellulose are basic components of the pulp needed. But the others belong to the components that shall be removed.
Main Property Index of Pulp
There are many property index of the pulp. To be summed up, it can be divided into two types: physical index and chemical index. The physical index is an important index to judge the value of the pulp. The tensile strength, breaking strength and tearing strength are main indicators of the imported pulp. Currently a large amount of the bleached and unbleached sulphate wood pulps, sulfite wood pulp and mechanical pulp are imported from abroad in China.
Inspection Standard of Paper Pulp Making
The imported pulp inspection mainly includes weight inspection and physical property inspection. The inspection standards include American Standard (TAPPI), International standard (ISO), Nordic standard (SCAN), Australian standard (APPITA), Canada standard (CPPA), etc.
As professional wood paper pulper machine manufacturers Anyang Machinery Co., Ltd. (AM) is affiliated to China National United Equipment Group Corp. Now the wholly state-owned key mainstay enterprise of China National Building Materials Group Corporation (CNBM) belongs to China National United Equipment Group Corp. under China’s State-owned Assets Supervision and Administration Commission of the State Council. AM has its own the R&D center of product design and provincial technical center. AM’s leading products include large chemical vessel, tower, reaction kettle, heat exchanger, a complete set of paper and pulp production line, batch cooking equipment, a complete set of pulping equipments for large chemical pulp production line, APMP poplar CMP equipment, multi-disc vacuum filter and complete sets of equipments for hollow brick, fly ash brick and aerated concrete block of production line. Meanwhile, AM is also working hard in a large number of the design, manufacture and installation of pressure vessel and machinery equipments referring to the industries of metallurgy, building materials, power and environmental protection, etc. in recent years.
