In this paper, the methods for determining the sizing degree of paper and cardboard are discussed, mainly including ink scribing method and liquid permeation method. The sizing degree is evaluated by measuring the paper's resistance to moisture, and the results are critical to the performance and application of the paper product. The article details the protocol, the instruments and reagents required to ensure that the test is performed under standardized conditions for reliable results.
introduction
Sizing is a measure of the ability of paper and cardboard to resist water permeation, and is usually expressed by the width of the ink stripe that is non-diffusing and impermeable. High sizing degree can effectively improve the durability and printing quality of paper products, which is very important for the application of paper in packaging, printing and other fields.
The degree of sizing directly affects the strength, water absorption and surface smoothness of the paper. Proper sizing reduces the effect of moisture on the paper, thereby improving its stability and service life in wet environments.
overview
Basic Principles of the Ink Scribing Method – This method determines the degree of sizing by drawing a standard ink line on the paper and measuring the degree of diffusion of the ink on the surface of the paper. The specific steps include adjusting the width of the scribe, applying ink, absorbing moisture, and measuring the width of the scribe, and finally using the maximum non-diffusion width as the sizing value.
Scope of application and application field - Ink scribing method is widely used in various types of paper and paperboard, including packaging paper, printing paper and industrial paper. This method is suitable for quality control in the paper production process, and can also be used to evaluate the performance of new materials to ensure that the product meets market needs and standards.
definition
The sizing degree refers to the index of the water resistance of paper and cardboard measured by the ink scribing method, which is specifically expressed as the maximum width (mm) of ink scribing under standard conditions. This indicator reflects the material's resistance to moisture penetration.
The measurement of sizing is usually done in accordance with industry standards, ensuring that different batches and types of paper are comparable. Terms such as "ink diffusion width", "permeation resistance", etc., are subject to standard test conditions to ensure data accuracy and reliability.
Instruments & Inks
scriber
The straight line pen used should be a high-quality duckbill pen with a smooth tip to ensure uniformity and stability of the scribing. Common specifications include the Round Large Pointed Pen and the Broad Flame Straight Line Pen to ensure suitable for paper testing with different sizing levels.
The magnifier should have at least 10x magnification and a scale to accurately measure the width of the line, and the scale should be 0.05 mm to ensure the accuracy of the test.
Standard inks
Standard inks are typically produced by professional ink factories, such as the Beijing Ink Factory, whose quality needs to meet relevant industry standards to ensure consistent and reliable results in sizing tests. The formula and viscosity of the ink should be in accordance with the regulations to avoid fluctuations in ink quality affecting the test results.
Sample taking, preparation, and handling
Samples should be performed according to a standardized sampling method to ensure representativeness and consistency. Random sampling is usually used to ensure that different batches and types of paper can be included in the test.
Samples are subjected to standard temperature and humidity treatment prior to testing to ensure that they are carried out under specified environmental conditions to eliminate performance differences due to environmental changes. Common treatment conditions are room temperature and relative humidity within a certain range.
Samples are cut to 150 mm x 150 mm squares and labeled on the front and back so that the results can be accurately documented and compared during subsequent tests. Make sure that the surface of the sample is flat and free of obvious blemishes.
Test procedure
Straightline pen width adjustment and checking
Before scribing, it is necessary to adjust the width of the straight line pen according to the requirements of the product standard, and check whether the pen end is smooth and parallel to ensure the uniformity and accuracy of the scribing.
Scribing operation
Direction and speed of scribing - When scribing, the straight line pen should be at an angle of 45° to the paper width, and the line should be scribed at a speed of 10 cm/s to ensure the continuity and stability of the line.
Line Measurement & Documentation – Immediately after scribing, the ink is blotted dry with filter paper and the width of the line is measured using a standard picture or magnifying glass, accurately documenting the results for subsequent analysis.
data processing
Air-drying and sizing degree identification - After the sample is air-dried at standard temperature and humidity for 10 minutes, the sizing degree is identified by using the "paper-to-ink permeation and diffusion comparison plate" to find out the maximum sizing width.
Specimen repetition test requirements - each test should be no less than three specimens, with the maximum width of the positive and negative test results to indicate the sizing degree of the paper or cardboard to ensure the reliability of the data.
Liquid osmosis
Reagents & Equipment
Preparation of ferric chloride and ammonium thiocyanate solution - 1% ferric chloride solution and 2% ammonium thiocyanate solution were configured, and pure ferric chloride and ammonium thiocyanate were dissolved in an appropriate amount of water and diluted to 100 ml respectively to ensure that the quality of the reagent met the experimental requirements.
Test procedure
Samples were taken according to the standard method, and the sample was cut to 30 mm x 30 mm, and a boat was made to float on the ammonium thiocyanate solution. Immediately after dropping a drop of ferric chloride solution inside the boat, the stopwatch timer is activated.
Record the time it takes for red dots to appear in the ferric chloride solution to the nearest second, for subsequent analysis.
Result Calculation – All measurements on the front and back sides are averaged and the coefficient of variation is calculated to evaluate the uniformity and reliability of the sizing degree, ensuring that the data reflects the true performance of the sample.
Capillary aspiration height determination (Krem method)
The principle of the test
This method evaluates the water absorption performance of paper by measuring the capillary absorption height of the paper strip after being soaked in water. The paper strip is suspended vertically in the water to record the height of the liquid rising, reflecting the hydrophilic nature of the paper.
Instrument and reagent requirements
The Krem Tester is used, the length of the scale is 200mm, and the index value is 1mm; Prepare distilled water or other solutions as required by the product standard. Make sure the instrument is clean and calibrated.
Assay preparation and sample handling
Samples were taken according to standard methods and treated with appropriate temperature and humidity. The sample is cut into 15 mm wide and 250 mm long strips of paper to ensure that the specifications of each specimen are consistent.
Test Procedures and Precautions
After clamping the specimen, immerse its lower end in water for 5 mm to start the stopwatch timer. Pay attention to record the height and time of liquid ascent to ensure accuracy. If the strip of paper is curled, use a small clip to keep it vertical.
Calculation and presentation of results
The longitudinal and transverse average aspiration height is calculated, and the results are expressed in mm/10 min or mm/s, ensuring that the time of liquid ascent and the handling method of the sample are indicated in the report.
Analysis and discussion of results
Analyze the repeatability and consistency of sizing determination results, and discuss the factors that affect the results, such as sample handling, experimental conditions, and measurement errors, to ensure the comparability and reliability of the results.
The sizing degree of different types of paper was compared, and the relationship between it and paper raw materials, production process and use was discussed, and the actual influence of sizing degree on paper performance was analyzed.
conclusion
The ink striping method and the liquid permeation method have their own advantages and disadvantages in the determination of paper sizing. The ink scribing method is simple and fast to operate, but the results are greatly affected by the operation technology. The liquid permeation method has high accuracy and is suitable for fine measurements, but the operation is relatively complex. Future research should focus on the exploration of new measurement technologies and the improvement of standardized processes to improve measurement accuracy and consistency of results, so as to provide a more reliable basis for paper performance evaluation.
summary
Accurate determination of sizing is an important part of the quality control of paper and cardboard. Through standardized experimental procedures, researchers can effectively evaluate the water resistance of materials, and then guide production and improvement. In future research, the effects of different materials and environmental conditions on sizing can be further explored to improve the accuracy and applicability of measurements.
