This standard specifies the preparation method for pulp brightness (whiteness) test samples. This standard is applicable to various wood pulps, bamboo pulps, straw pulps and cotton and linen long fiber pulps cut to appropriate lengths. GB/T 8940.2-2002 Preparation of pulp brightness (whiteness) test samples GB/T8940.2-2002 Standard download decompression password: www.bzxz.net

GB/T 8940. 2—2002
This standard is a revision of GB13/T8940.2—1988 pulp brightness determination method. This standard is equivalent to ISO3688:1999 "Preparation of pulp brightness (brightness) samples". The difference between this standard and (BT8940.2-1988) is that this standard only stipulates the preparation of pulp brightness (brightness) samples. The determination of brightness (whiteness) is included in (GB/T7974---2002 "Determination of brightness (brightness) of paper, paperboard and pulp (diffuse/vertical method)". This standard is proposed by China Light Industry Federation. This standard is under the jurisdiction of the National Technical Committee for Standardization of Paper Industry. The drafting units of this standard are: Inuijin Light Industry Paper Technology Research Institute, China Pulp and Paper Research Institute. The main drafters of this standard are: Zhang Jingyan, Hou Weiling, Du Liping. This standard was first published in 1988 In August 2002, this standard was entrusted to the National Technical Committee for Standardization of Paper Industry for interpretation. GB/T8940.2-2002
ISO Foreword
ISO (International Organization for Standardization) is a global federation of international standardization bodies (ISO members). The formulation of international standards is usually completed by ISO technical committees, in which each member country has the right to express its opinions to the committee if it is interested in the standards issued by the technical committee. International organizations related to ISO (governmental and non-governmental) can also participate in this work. ISO has close ties with the International Electrotechnical Commission (IEC) in the field of electrotechnical standards. ：
The draft of an international standard must be voted on by all members of the technical committee before it can be formally adopted. The formal publication of an international standard requires a voting rate of not less than 75%. International Standard ISO 3688 was drafted by ISO/TC6 Paper, Paperboard and Pulp Technical Committee SC5 Test Methods and Quality Specifications for Paper.bZxz.net
The second edition cancels and replaces the first edition (IS03688:1977) and its technical revisions. 1 Scope of application
National Standard of the People's Republic of China
Preparation of pulp brightness (whiteness) test samples
Pulp- -Preparation of laboratory sheets forfhc measurement of brightnessaess This standard specifies the preparation method for pulp brightness (whiteness) test samples. GB/T 8940, 2-2002
eqIso3688.1999
Replacement GB/T 8940.2-1988
This standard is applicable to various wood pulps, bamboo pulps, straw pulps and hemp long fiber pulps cut to appropriate degrees. 2 Referenced standards
The provisions contained in the following standards become the text of this standard through their use in this standard. At the time of publication of this standard, the versions shown are all valid. All standards are subject to revision. Parties using this standard should explore the possibility of using the latest versions of the listed standards. G13/T 740--1089 Taking of pulp samples (c41S0 7213:1981)GI5/T7974～2002Determination of brightness (degrees) of paperboard and pulp (diffuse/vertical method)neqIS02470:1999)QH/11462-1992Disintegration of pulp laboratory (e1VI505263:1979)23/Ting3703--1S99Preparation of pulp laboratory paper Conventional paper negative forming method (eVES0)5269-1:1979)3 Technical equipment
All equipment in contact with pulp should be made of corrosion-resistant materials, such as glass ceramics or stainless steel, and iron, copper, yellow feather and blue steel should be avoided. Because iron ions and copper ions can strongly cause pulp discoloration. 3.1 Standard deflakers should comply with the provisions of QB/T462. 3.2 Pulp samples prepared by using a filter
3-2.1 A Brinell filter or similar device made of corrosive material, with a flat bottom, an inner diameter of 115 mm~150 mm, a volume of 100 mL-1500 mL, and connected to a vacuum pump. 3.2.2 White cloth, diameter 115 mm~150 mm, free of inflammatory substances and soluble properties. 3.2.3 Grade, about 250 m/m, free of inflammatory substances and soluble substances. Used to clamp the sample and absorb the moisture. 3.2.4 Qualitative filter paper,
3.2.5 Pressing plate. Made of stainless steel or hard plastic, its size is the same as the test piece, thickness 1mm~1.5mm. 3.2.6 Machine,
3.3 Pulp samples prepared by paper pressure reducer. 3.3.1 Paper former, in accordance with the provisions of Q/3-03. At the same time, all parts or equipment in contact with the pulp should not cause discoloration of the pulp.
3.3.2 Press.
3.3.3 pH, calibrated to an accuracy of 0.1, approved by the General Administration of Quality Supervision, Inspection and Quarantine of the People's Republic of China on October 15, 2002, implemented on April 1, 2003
4 Reagents
GB/T 8940.2—2002
In the process of preparing pulp samples, analytical reagents, distilled water or pure water without coloring matter, iron ions and sodium ions should be used. 4.1 Sodium hydroxide (NaOH), concentration is 0.1 rranl/E., that is, each liter of solution contains 4.0g of sodium hydroxide, 4.2 (HS)) = D.05mol/L. That is, each solution contains sulfuric acid (density 1.84g/ml.) 2.8m. or c(CHCOOH)-0.1mol/l-. That is, each liter of solution contains acetic acid (density 1.05g/.295tml.4.3 Retention aids, hand-recovered pulp and non-original pulp, contain some fine fibers and small separation products that are different in color from long fibers. It can affect the brightness (whiteness value but cannot be retained when passing through the filter. For this reason, retention aids should be added before the pulp sample is formed. If 0.4% retention aid is added during the intermediate pulping, these effects can be eliminated. It seems that the type of retention aid should be stated in the test report. 5 Sampling
Samples are extracted according to GB/T70. During the storage of the sample, the influence of heat and light on the sample and the change of moisture in the sample should be prevented: the detailed amount should be sufficient to prepare 4 fixed Dongs for 20 g/m2 sample. 6 Sample preparation steps
6.1 Pulp treatment
6.1.1 Pulp board or pulp sheet
Cut the pulp board or pulp sheet into pieces of about 20mm~30mm, and weigh out the pulp required to prepare 4 200g/m2 samples. Soak in water for 30ml and then deflake according to the provisions of QB/T1462. The lowest deflaking speed can completely separate the fibers. Finally, dilute the pulp suspension to 4 g/L.
6.1.2 Wet pulp
Determine the pulp concentration and measure out the appropriate amount. 6.2 Preparation of test samples
6.2.1 Use a pH meter to determine the pH value of the pre-treated pulp. If the pH is not between 4.7 and 5.5, use sodium hydroxide (4.1) or ethyl acetate (4.2) to adjust it to this range. If the pulp contains substances that can dissolve at pH = 5, its pH value should be adjusted to 6.0.-7.0. If it is grass fiber, adjust the pH to less than or equal to 1. However, it should be noted in the test report. 6.2.2 Preparation steps of the leakage method
Stir the pulp and divide it into several portions. Each portion contains pulp for preparing 200g/m2 test samples. . Place the non-silk cloth (3.2.2) in the funnel, moisten it with water and burn it flat. Take 1 portion of the pulp into the funnel and filter the water by aspiration until the mirror surface disappears. Avoid excessive suction on the formed pulp sample, which may cause small air to be trapped. Turn the funnel upside down and remove the pulp sample with air. Connect it with a piece of filter paper, gently remove the silk cloth and put it back into the funnel, and mark the direction of the sample (not on the filter paper side). Prepare 4 samples according to the above method. Place the prepared samples in the following order. a) a pressing plate;
l) two blotting papers;
) Sample covered with floating paper:
l) two blotting papers;
) a plate.
Clamp the remaining samples in this order.
Put the sample in a pressurizer and pressurize it at a pressure of about 0kPa for 1 minute (the pressure is often different from the pressure gauge reading). Before pressurization, make sure that the sample is in the center of the pressure plate. Then remove the filter paper from the sample and put it back in place to protect the sample. Hang the sample and the thin paper together in a non-oxidizing gas cylinder and dry them at room temperature to 5-15°C. The semi-drying time should not exceed 24 hours. Then put the sample protected by the filter paper in a pressurizer and press it at a pressure of 300kPa-500kPa for 30 seconds to make the sample as flat as possible. Paper sheet former method preparation must be
GB/T 8940.2--2002
According to QB/T 3703, the sample weight is 200 g/m\,Distilled water or water of equivalent purity should be used. Dry the sample protected by filter paper at room temperature until the moisture content is 5%~15%. The drying time should not exceed 24h. Press the sample according to 6-2.2.
7 Storage of samples
Ensure that the prepared samples are not contaminated and avoid exposure to strong light and heat. The brightness of the samples should be measured immediately after preparation. The longest time should not exceed 10h after drying.
B Test report
The test report should include the following items:
a) This standard number;
|b) The name of the sample and necessary instructions for the preparation process; c) Any operation that deviates from this standard and abnormal conditions during operation.
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