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Everything has its own source and toilet paper is no exception. Pulping is the first step in the production of toilet roll paper. Next I’ll give a brief introduction to pulp.
Paper pulp is a fibrous material made of plant fibers and processed by various processing methods. According to the processing methods, it is divided into mechanical pulp, chemical pulp and chemi-mechanical pulp(CMP for short); fiber sources into wood pulp, straw pulp, hemp pulp, reed pulp, cane pulp, bamboo pulp, rag pulp ; different purity into refined pulp, bleached pulp, unbleached pulp, high yield pulp and semi-chemical pulp . Pulp is generally used to make paper and cardboard. Refined pulp, which is used not only for making specialty paper but also as the raw materials of cellulose derivatives such as cellulose ester, cellulose ether, is applied into the fields in the form of man-made fibers, plastics, coatings, films and gunpowder.
Pulp, made of fibers form some plants , it is the basic raw material for paper making. Plants commonly used for pulping can be divided into four categories: stems and fibers, bast fibers, woolen fibers and wood fibers. Among them, the wood fiber is the most important. At present, China's timber resources can not meet the growing needs of the pulp and paper industry. Consequently, in order to make up for the lack of timber, a considerable amount of pulp is imported mainly from the United States, Canada and Brazil each year.
Conventional pulping refers to the production process of dissociation of plant fiber into its natural color or pulp-bleaching through chemical methods, mechanical methods or the combination of the two methods. The usual processes include crushing, cooking, washing, screening, bleaching, purification, drying.
A new biological pulping method is developed first beginning with the specifically directional decomposition of lignin structure with a special strain (white rot fungi, brown rot fungi, or soft rot fungi) , then with dissociation of the remaining cellulose through the mechanical or chemical methods and bleaching. In this whole process, the strain has been decomposed and most lignin dissociated, and the chemical method plays only a supporting role. The use of chemical products is much less than the traditional method, thus little or no liquid waste is created, which makes the biological pulping an environmentally friendly , clean pulping method.
① According to the production method, pulp is divided into 3 categories: chemical pulp (including caustic soda pulp, sulphate pulp, sulfite pulp, etc.), mechanical pulp (including grind wood pulp, grinding mill mechanical pulp, hot mill mechanical pulp, etc.) and chemi-mechanical pulp;
② According to raw materials, pulp is divided into wood pulp, straw pulp, bamboo pulp, cotton pulp, waste paper pulp, etc. ;
③ According to the processing depth, pulp is divided into unbleached pulp, semi-bleached pulp, bleached pulp, refined pulp, etc .;
④According to the yield rate of wood, it is divided into chemical pulp (yield rate 40 ~ 50%), high yield chemical pulp (yield rate 50 ~ 65%), semi-chemical pulp (yield rate 65 ~ 84%) , chemi-mechanical pulp (yield rate 85 ~ 94%) and mechanical pulp (yield rate 94 ~ 98%);
⑤ According to its use, pulp is divided into self-use pulp for the sake of the company and a commercial pulp for sells. For a specific variety of pulp, it is often named in several different classification methods, such as bleached sulphate softwood pulp, natural sulphite reed pulp, poplar wood pulp, etc., so that the user can understand the performance and application of the pulp at the sight of its name.
The content from the second paragraph to the fifth paragraph comes from Baidu (www.baidu.com), which gives a very professional explanation to pulp. Paper mill industry not only makes our daily used papers like toilet paper but also industrial papers such as books, cartons, packaging and so on.
But here we mainly focus on the pulp related to the toilet paper. From the above information, we know the definition of pulp, a fibrous material processed from plant fibers as raw materials.
To understand the definition, close attention must be paid on the key words "plant fiber" and "fibrous material". First of all, don’t confuse plant fiber with animal fiber. Plant fiber is a thick-walled tissue widely distributed in the seed plants. It mainly functions as a mechanical support, which, simple to say, means it’s able to support plant fine tissues and processed into pulp.
This explanation in a micro way may sound not easy to understand, then I will explain "pulp board" in a more macro way. Pulp board is a kind of pulp, a thick cardboard pulp from dehydrated and pressed pulp . It weighs generally more than 250 grams and is easy to transport. Since many paper mills do not have their own pulping lines, they need to buy pulp from the pulp mills and then crush them into pulp.
The following figure is the pulp board.
Usually, four pulp boards form one 1-ton bundle with each pulp 250-kg. Each bundle is much heavier than it looks like.
You may find it easier to understand after the explanation. At present, most domestic paper mills use pulp board as a direct source to obtain raw materials and extract fiber. In addition, who provides pulp boards is pulp pulp mills.
So how do the pulp mills make pulp? What are the plants that offer plant fibers? Some of you may know the answer . Yes, the plants are "trees". And more will be talked about in the next section.
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