Sanitary paper refers to all kinds of sanitary wipes used for personal home, outing, including roll toilet paper, removable toilet paper, boxed facial tissue, pocket paper, handkerchief paper, napkin, kitchen paper, and wet wipes, shoe-shining paper, paper towels, and etc.
Sanitary paper is mainly used for daily hygiene of people’s lives. Therefore, the sanitary paper is usually called household paper, which is one of the indispensable paper types in people’s lives. Its shape has a single square shape, called kerchief or facial tissue, but also rolled into the shape of a cylinder, called roll paper. They are usually made of cotton pulp, wood pulp, straw pulp, and waste paper pulp. The good quality toilet paper is made of virgin wood pulp. It is similar to the general paper manufacturing process, but required to be extremely thin and extremely fragile. Sanitary paper is rotted when it encounters water, achieving environmental protection.
Sanitary paper pulp processing
Sanitary paper is generally made from the pulp board, which is made from some fiber materials, such as wood, bamboo, reed, sugarcane bagasse, cotton, waste paper, etc.
What is the pulp board? The pulp board is a kind of pulp, which is a kind of thick paperboard formed by the pulp after dewatering and pressing. The weight of the paper is generally more than 250 grams. The pulp board is mainly convenient for transportation in the paper industry. Because many paper mills do not have their own pulp production line, they need to buy pulp boards from the pulp mill and then break them into pulp.
- Pulp board: transport and stock pulp board for preparation
- Repulping: Uses the paper pulper to separate the pulp board. After pulp gets moisten by absorbing the water, the pulp is subjected to hydraulic shearing force by the rotation of the impeller, thereby dispersing the pulp.
- Deslagging: Remove heavy impurities like sands or scree according to the specific gravity of the object under the action of centrifugal force.
- Defibering: The directional friction between the turntables is used to separate the fiber bundles to increase the productivity of the pulper.
- Grind into thick liquid：Using the mechanical action of the grinding disc on the fiber and the extrusion of the fiber to the fiber, makes the fiber deuterated, and change the physical form of the fiber.
- Blend the pulp: The process of mixing two or more kinds of pulp in a certain ratio.
- Paper machine: use the paper machine process the pulp, including forming, pressing, drying and wrinkling.
Raw materials of sanitary paper making
In general, sanitary pulp board is made from some kinds of pulp, including recycled pulp, wheat straw pulp, softwood pulp, hardwood pulp, bagasse pulp and mixing pulp of softwood and hardwood.
Recycled pulp, also known as reclaimed pulp, is mainly used for recycling and recycling waste paper. This kind of pulp has low whiteness and contains a large amount of ink and stickies. In the pulping process, the ink is removed by adding a deinking agent, and the remaining part is mainly dispersed by hot grinding to disperse the residual ink and the stickies into small particles, which are not remove and stay on the paper in the papermaking process.
Therefore, the low whiteness of the waste paper pulp usually increases the whiteness by adding a whitening agent, and the problem of the hair loss is serious. So, it is only applied to manufacture the low-grade household paper, and the paper is gradually eliminated in the country as the living standard of the residents is improved. It is still used in rural areas as well as in small restaurants.
Recycled pulp household paper can be slightly blue reflected by observing the color, and a large amount of dust will fall off by hand, and black ink dots can be observed due to residual ink.
Wheat straw pulp
As the name suggests, wheat straw pulp is made from wheat straw. The wheat straw pulp fiber is shorter, the whiteness is lower, the number of miscellaneous cells is more, and the non-fibrous cells of wheat straw pulp are as much as 30%-50%, while the softwood pulp is less than 5%, the hardwood pulp contains about 20%, so the paper strength is low, the problem of hair loss is serious, and the paper is hard. China has ample wheat straw pulp as a large agricultural country. In the last century, wheat straw pulp dominated the domestic market. However, with the development of environmental protection, wheat straw pulping has gradually eliminated because of a large water consumption and pollutions.
In recent years, due to the poor whiteness of the bleaching straw pulp, some enterprises choose to manufacture unbleached straw pulp. Although the amount of bleaching agent is reduced, and the pulp yield is improved after eliminating the bleaching stage, there is no reduction of cooking waste liquor that is the main pollutes of straw pulping, and a large amount of lignin remains in the obtained pulp, and it is difficult to remove the residual chemicals only by washing with water.
As a raw material for household paper, wheat straw pulp has poor physical properties during the papermaking process. In order to achieve good physical properties, more functional chemicals need to be added during the papermaking process to improve the paper strength and feel the hand.
Hardwood pulp mainly refers to the pulp made from trees with wide or blade-like leaves. Common hardwood for pulping includes white poplar, maple, birch, etc. In the pulping process, the hardwood pulp is mostly washed with chlorine-free bleaching and multi-stage countercurrent washing to obtain a pulp with relatively pure cellulose. Since the hardwood pulp fiber is short and soft, it can produce paper with good hand feeling, but due to the low strength, the hardwood pulp is used as the surface layer in the papermaking process.
Softwood pulp is commonly made from pine, spruce, fir, etc. The softwood pulp is similar to the hardwood in the pulping process, but the cooking process needs to be provided a higher temperature. The softwood fibers are longer and wider. It can improve the high strength of paper, and it is mainly used as the reverse side to improve the strength in the papermaking of household paper.
The bagasse pulp is extracted from the sugarcane of southern sugarcane. The main production area of sugarcane pulp is located in the south, and the yield is low. Because the sugarcane pulp is hard, it is usually used for papermaking such as paper towels.