Paper is the most commonly used item in our daily life. Whether reading books, reading newspapers, writing or painting, we have to contact with paper. In the production of industry, agriculture and national defense industry, paper is also indispensable. Paper making is one of the four great inventions in China. Looking back on history, paper is the accumulation of long-term experience and the crystallization of wisdom of the working people in ancient China. It is an outstanding invention and creation in the history of human civilization.
Cai Lun improved papermaking in the first year of Yuan Xing in the Eastern Han Dynasty (105). He used bark, hemp and crepe, fish net and other raw materials, and the paper made by frustration, simmering, frying, baking and other processes is the origin of modern paper.
In the process of papermaking，the foam problem is troublesome.Foam prevents the normal execution of papermaking process and the normal operation of the equipment. If the foam can not be completely eliminated, it will become a serious problem in papermaking and waste liquid treatment.With the development of domestic paper industry, defoamer has become an important research topic in production. Paper-making process is divided into two main steps, one is washing pulp, the other is papermaking. Next,SIXIN will provide you with a comprehensive explanation of the impact of foam on papermaking and the role of papermaking defoamers based on science and technology, and the application process of papermaking defoamer products.
1. How much impact will foams have on paper making?
The impact of foam on pulp making
For pulp making, the generation and presence of foam will seriously affect the normal operation of washing, screening, bleaching and beating of the slurry, so that these processes and equipment can not effectively function, thus delaying the production cycle.
The impact of foam on papermaking
For papermaking, the impact of foam is even greater.
(1) The foam in the paper material affects the concentration of the headbox, making the paper material flow unstable;
(2) The foam will seal the pores on the surface of the wet paper and cause wet-end difficult to dehydrate. The fibers and the dispersed fillers will coagulate in the mesh, thus affecting the uniformity of the paper.
(3) Excessive foam forms a floating slurry, which makes the net block appear when the headbox, and even breaks the head when it is serious.
(4) In papermaking, foam stability exists between cardboard layers, which will affect the combination of paperboard and reduce bonding strength.
(5) A large amount of foam will also cause paper problems such as foam holes and foam spots.
2. the role of paper defoamer and selection requirements
(1).In the process of pulping, the slurry contains fatty acids, resin acids and other natural substances. After cooking liquid and chemical washing, fatty acid soap, fatty acid soap and other foaming substances will be generated. A large amount of foam will cause some trouble for subsequent cleaning and transportation and bleaching, resulting in a decline in pulp quality. Therefore, defoamers should be used.The defoamer used in the pulping process is mainly divided into two categories: hydrocarbon defoamer and silicone emulsion defoamer. This kind of defoamer can quickly remove the foam produced by lignin and some surfactants, especially when it is used for pulping and washing.
Defoamer for papermaking and pulping is mainly used to control the foam produced by alkali pulping, papermaking, washing, bamboo pulp, cane pulp, neutral pulping, pulp, pulp rinsing, screening, bleaching, water treatment, and plant fiber pulp production. It has the following characteristics:
(1) Strong defoaming and knocking down
(2) Rapid and thorough improvement of filter drainage
(3) Good mutual solubility in black liquor, suitable for pulp mill production conditions
(4) It can improve the rinsing efficiency
(5) Reducing salt loss and improving pulp quality
(6) The raw material is biodegradable, non-toxic and harmless
(7) Reduce the content of bleaching chemicals to meet environmental protection requirements.
For the papermaking process, if the foam generated in the papermaking process is not solved, it will lead to paper breakage, white water level fluctuation, pump frequency fluctuation, etc., which directly affect the stability and quality of paper production.The papermaking defoamer can effectively inhibit the white water foaming, and at the same time, can eliminate the fine foam on the surface of the slurry and the fine bubbles entrained between the fibers. The defoamer can also dissolve the air in the pulp and eliminate the bubbles on the water surface, thus avoiding the formation of voids, reducing the overflow of paper breakage and pulp storage tank, thus ensuring the loss of pulp fibers and chemicals, and improving the uniformity and quality of paper.
Defoamer for papermaking:
The defoamer used for papermaking is applied to white water for papermaking. The surface foam containing rosin glue, bubbles adsorbed on water fiber, surface foam containing aqueous modified starch white water system, water foam containing polyacrylamide retention aid system and surface foam containing AKD emulsion white water system are eliminated. Its main characteristics are:
(1) The defoaming speed is fast and the inhibiting foam time is long.
(2) Good dispersion, dynamic defoaming and silicon-free;
(3) Good product stability.
Recommendation for papermaking defoamer
To eliminate foam in papermaking industry, there are usually two ways, chemical defoaming and mechanical defoaming. However, the most commonly used and effective method is chemical defoaming, because it does not need to invest a lot of equipment and maintenance costs, do not need to change the original paper-making process, just add defoamer to the place where defoaming is needed, and defoaming fast, inhabiting foam time is long, will not react with the system, will not have negative effects of paper or cardboard production.
(1) Adding a small amount of defoamer can achieve excellent defoaming effect and it will be competitive.
(2) It has the effect of defoaming and anti-foaming stably under strong alkali and high temperature environment, and has shear resistance.
(3) Good chemical stability, no side effects on the system, non-toxic to the environment and environmental protection;
(4) Quick and thorough improvement of filter drainage;
(5) Good mutual solubility in black liquor, suitable for pulp mill production conditions;
(6) It can improve rinsing efficiency, reduce salt loss and improve pulp quality.
(7) Reduce the content of bleaching chemicals to meet the requirements of environmental protection; raw materials are biodegradable, non-toxic and harmless.
SIXIN Defoamer Business Service Guidelines:
1. Provide defoamer analysis and testing services;
2. Provide defoamer performance and process improvement services;
3. Provide services for formulation and customized defoamer.
4. Provide advisory services for technical experts to guide production and solve technical problems.
5. Provide defoamer mature technology transfer and teaching services;
6. Provide frontier information, product application and new product recommendation services of defoamer industry.
Post time: Sep-06-2019