A brief term for the hottest beating

The brief term of beating

(1) beating degree: beating degree only indicates the water filtration performance of pulp. Dilute 2 grams of absolute dry pulp to 1000 ml, and the amount of water discharged from the measuring tube of Shaw beater at 20 ° C through 80 meshes is the result of the determination. Beating degree is an indicator of the properties of paper. According to the beating degree of paper, it is possible to master the water filtration speed of paper on the copper of the paper machine in the future, and it is also possible to predict the mechanical strength, tightness and finishability of paper in the future. Therefore, mastering the beating degree of paper is an important technical control method in production. Beating degree alone cannot fully represent the properties of paper. For example, we can achieve 45 ° SR by highly cutting fibers (free beating). In addition, we can also achieve the same 45 ° SR beating degree by highly fine fibrosis (sticky beating), but not how to cut short. Although the final beating degree of the two cases is the same, the properties of the paper material are quite different. Therefore, it has shortcomings to rely on the beating degree as the only control index in production technology in production, which must be considered in combination with other indexes such as the average length of fiber, so as to carry out reasonable beating

there are many kinds of instruments for measuring the beating degree of paper materials. Chinese paper mills generally use Shaw beating degree instrument

(2) Canadian standard freeness (C.S.F.): there are various methods to determine the water filtration performance of pulp, among which freeness and beating degree are widely used. North American countries and Japan mostly choose Canadian standard freeness, while Europe and China are accustomed to using Shaw beating degree. The difference between freeness and beating degree is only the measurement table, but not the difference in method. The greater the beating degree, the smaller the freeness of the paper, and vice versa. Generally speaking, the greater the freeness of the paper, the faster the water filtration speed. The measuring instrument used for the Canadian standard freeness is similar to the Shaw beating degree instrument, but the absolute dry fiber sampling amount is 3 grams during the measurement, and the freeness and beating degree can be converted to each other

(3) water retention value: under the standard state, use a high-speed centrifuge to throw out the free water in the paper material, and quantitatively measure the amount of water retained in the paper material, so as to obtain the water retention value of the paper material and the resulting fiber plasticity. This method uses centrifugal separation to keep only swelling water between fibers, and only a small amount of fiber surface water and water between fibers. Therefore, the water retention value index can explain the degree of fiber swelling, thus reflecting the degree of fine fibrosis and the degree of adhesion between fibers

beating degree can only measure the water filtration performance of paper. However, it was learned from Ningbo Municipal Commission of economy and information technology and other departments that the increase of beating degree does not mean that the paper strength will increase in a straight-line proportion. However, the increase of water retention value in the beating process is consistent with the increase of strength. The strength of paper mainly depends on the adhesion between fibers and fiber length, so measuring the water retention value and then measuring the average length of fibers can well explain the strength of paper. At present, it is generally believed that the determination of these two indicators is more illustrative than the beating degree index alone. However, due to the expensive equipment and troublesome determination procedures, they are not widely used. At present, they have not been officially adopted in the production of domestic paper mills

(4) wet weight: wet weight is a term commonly used in beating process control, which indirectly indicates the average length of fibers. The wet weight is mostly measured by the frame method, which uses a special frame to make the diluted paper flow through the frame while measuring the beating degree, and the weight of the fiber hanging on the frame is the wet weight. The longer the average length of fibers in the paper, the heavier the fibers hanging on the frame, that is, the greater the wet weight

(5) hydration degree: some factories also use hydration degree as an index. First of all, in the paper industry, the term "fiber hydration" is not strict enough, because it is easy to misunderstand that fiber and water play a chemical role. In fact, water forms a water bridge with hydroxyl groups on the fiber, and dehydration forms a hydrogen bond when drying, which is not a chemical action. Hydration degree is a method that indicates the absorption and combination of fibers in the beating process, so that the software system of the control equipment can disconnect the total amount of water from the equipment. One of the measurement methods of hydration degree is boiling method, that is, heat the paper for 1 hour, remove the bound water of the fiber by heating method, and then measure its beating degree according to the common method; The degree of hydration of paper fibers is represented by the difference between the beating degree measured by unheated paper and heated boiled paper. The other is alcohol method, that is, put the paper in alcohol, use alcohol to replace the bound water of the fiber, and then use the ordinary method to measure the beating degree. The difference between the paper in water and alcohol indicates the hydration degree of the paper. The above two methods for determining the degree of hydration of fibers have some shortcomings, which are easy to cause errors

conversion table between Canadian standard freeness and shore beating degree

Canadian standard freeness (ML) shore beating degree (° SR) Canadian standard freeness (ML) shore beating degree (° SR) 25 90.0 425 30.0 5080.0 450 28.5 75 73.2 475 26.7 100 68.0 500 25.3 125 63.2 525 23.7 150 59.0 550 22.5 175 54.8 575 21.0 200 51.5 600 20.0 225 48.3 625 18.6 250 45.4 650 17.5 275 4 but 3.0 675 16.5 300 40.3 700 15.5 325 38.0 725 14.5 350 36.0 750 13.5 375 34.0 775 12.5 400 32.0 800 11.5