Recently, the price of paper towels in many parts of the country, at the same time, life paper, culture paper also followed the price of the beginning.
Soft toilet paper, hard paper that can cut fingers, what are the differences in the manufacturing process of different paper uses? Daily paper why can this time rise in price? To answer these questions, we need a basic understanding of the paper production process.
Where did you get the paper you use?
In a word, paper is an industrial product made from fibers extracted from plants. If you look at paper with a high-powered microscope, you will see that it is actually a network of layers of fibers superimposed on each other, with Spaces between them.
There are three main sources of fiber raw materials used in papermaking: wood pulp from wood, non-wood pulp from herb fiber and waste paper pulp from waste paper. The wood pulp is divided into coniferous pulp and broadleaf pulp, while the non-wood pulp is mainly composed of grass fiber pulp (such as straw, wheat grass, reed, bamboo, bagasse, etc.), bast fiber pulp (such as hemp, kenaf, flax, mulberry bark, cotton stalk bark, etc.) and seed hair fiber pulp (such as cotton fiber, etc.).
According to the processing method of pulp, it can be divided into mechanical pulp, chemical pulp and chemical mechanical pulp. Here the mechanical and chemical means are the main processes that depend on the preparation of raw materials into pulp.
Through the source and processing, we can subdivide the pulp into mechanical wood pulp, chemical wood pulp, etc., so as soon as you hear the name, you can have an intuitive understanding of the properties of the pulp. In the actual production, the proportion of wood pulp is much higher than that of non-wood pulp, but the vast majority of papermaking raw materials are actually waste paper pulp. Of course, most of the waste pulp also comes from wood pulp, so let's take the most mainstream chemical method as an example to talk about how wood pulp is produced.
How to turn wood into pulp?
In addition to specially cultivated tree species, most of the wood used for making wood pulp is wood waste with no other use value. For example, leftover leftover materials from cutting boards and rods, leftover wood with too many winding parts that can't be used, thinning wood cut off during regular cutting and trimming of forests, and construction waste taken out when demolishing old wood buildings, etc.
Generally, wood pulp is made from coniferous trees such as pine and broadleaf trees such as eucalyptus or acacia. Conifers have longer fibers and are suitable for making paper bags or envelopes, which require higher strength, while broadleaf trees have shorter fibers and a better surface finish, which is suitable for printing and household paper.
The wood for pulping is first cut and pulverized to make small wood chips, and then it is boiled with sodium hydroxide solution. The so-called chemical method is this process, which can separate cellulose and lignin. Like glue, lignin holds cellulose together and is the main substance that makes wood stronger. After the separation of wood fiber filtration and bleaching and other processes, we often heard of wood pulp.
For ease of transportation, wood pulp is not a sticky substance like slurry, as we might think, but a lump of dried and compressed fibers. The finished wood pulp looks like cardboard or felt, stacked on top of each other. Most paper mills do not produce wood pulp themselves, but purchase from upstream manufacturers. Generally, only the larger paper mills will build a full set of paper production lines from wood pulp to paper products.
Wood pulp to paper, the process is not mysterious
From trees to pulp, it is only the first step, the next process is the key to making any kind of paper. Let's take the production of facial tissues as an example to describe the specific process of paper making.
When the pulp arrives at the paper factory, it is put into a pulper, where it is mixed with water and stirred. The pulper acts like a giant washing machine, separating as much fiber as possible from the wood pulp. After going through a pulper, the wood pulp is diluted into a raw material solution of about 6% by mass. In the next process, the wood pulp is further diluted by water to a dilute solution of about 0.2% by mass.
Next, the wood pulp solution goes into the paper making machine, which is a key process for forming the specific thickness and properties of the paper. The wood pulp solution is then spread across the surface of a plastic mesh mold called a paper mesh, where it is flattened to form a uniform film of uniform thickness with evenly distributed fibers. The size of the sheet paper net is usually nearly 20 meters long and 5 meters wide.
Next, the water in the intermediate form film is extruded by rollers and then heated and dried. Finally, the surface and shape of shaping, rolled into a roll of base paper. The linear speed of the roller used for paper rolling can reach 120 kilometers per hour, and a roll of the base paper may be ten thousand meters long and weigh five to six tons. Before leaving the factory, the base paper roll will be cut into the required size, and then packaging transportation.
How can a similar process produce a variety of paper
All kinds of paper are processed in the same way, but the paper in our daily life has a completely different purpose and texture: some are used for writing, some for hygiene, and some for packaging. How can similar processes produce completely different paper products? The secret is that their production parameters and processes are slightly different. For example, we mentioned above that the ratio of coniferous pulp, broadleaf pulp, and waste pulp in the pulp is one of the key parameters determining the properties of the paper. In addition, the dilution and stack thickness of paper pulp will also make the paper has different density and thickness, which directly determines the use of paper.
Water content is also a critical factor. Hygiene papers, such as toilet paper, have a high water content of about 5 percent, which is key to their soft touch. Sometimes, we want the paper to be soft and strong enough that it won't break when it comes into contact with water or gets stressed. To address this need, paper mills add paper strength enhancers to the paper process, which form bonds between the fibers and improve the paper's resistance to water and external forces. The addition of paper strength enhancers and other chemical reagents is a necessary process in the papermaking process. The content of these additives is small and will not cause damage to the human body and the environment.
Why does paper cost more?
At the same time, there are many paper mills suspended production of the news. Shouldn't manufacturers be ramping up production when prices rise? Why suspend production instead?
Through the above analysis, it is not difficult to find that in order to produce a piece of paper, the paper mill needs to import the pulp from the upstream paper mill before it can produce all kinds of paper. Paper manufacturers and pulp manufacturers organize production separately, which belongs to the upstream and downstream of the industrial chain or the relationship between suppliers and buyers. Therefore, the cost of raw materials largely determines the profit margin of enterprises in the middle and lower reaches of the industrial chain. Most of China's paper companies are located in the middle and lower reaches of the paper industry chain, and wood pulp imports account for more than two-thirds of the raw material, making the situation quite passive.
The root of this price hike is actually a temporary fluctuation in international pulp supply. On the one hand, due to the impact of the epidemic, the cost of international shipping has increased, and pulp is heavily dependent on shipping as a commodity. On the other hand, the paper industry has a certain consumption of forest resources, so the major wood pulp producing countries also need to rationally organize wood pulp production to balance short-term interests and long-term interests. In addition, China has recently implemented stricter import management measures for solid waste materials, which directly restricts the import of waste paper materials from abroad.
The above reasons make the price of paper raw materials greatly increased, so that many paper processing plants are not profitable, so they choose to suspend production. But on the positive side, higher raw material prices for the paper industry may instead be an opportunity to remove outdated capacity.
Paper is an important material that people can not live without. It is gratifying that at present, recycled paper has accounted for more than 60% of pulp raw materials. But not all kinds of paper are recyclable, which shows the importance of recycling and careful sorting of waste. There is no need to promote extreme environmental protection, paper should still be used, but to avoid unnecessary waste, and at the same time to improve the recycling of paper.
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