Method for detecting starch content of cardboard paper

Abstract

The invention discloses a cardboard paper starch content detection method, and relates to the field of starch content detection.The cardboard paper starch content detection method comprises the steps that S1, firstly, the whiteness and the L value of each paper sample are detected through a colorimeter CA60 and a whiteness meter ZB-B, recording is made, then according to the principle that iodine becomes blue when encountering starch, the paper samples are sprayed with a 0.5% iodine solution and then aired, whether the color of the paper samples changes or not is observed, and if yes, whether the color of the paper samples changes or not is judged; the whiteness and the L value of the discolored paper pattern are different. According to the method for detecting the starch content of the cardboard paper, multiple paper samples made of different materials are adopted for comparison in the first step, so that the starch content of the cardboard paper with large whiteness difference and L value difference and surface sizing is higher, otherwise, the starch content of the cardboard paper with large whiteness difference and L value difference is lower, and the same variety and quantitation can be compared with each other; therefore, the difference of the surface sizing starch content of paper samples of different manufacturers and different varieties can be qualitatively and intuitively judged.

Description

Technical Field

[0001] The invention relates to the technical field of starch content detection, in particular to a method for detecting starch content of boxboard paper. Background Art

[0002] The structure of waste paper raw materials of domestic packaging paper enterprises has changed greatly. Except for a small amount of imported recycled pulp, it has basically entered the "internal circulation" of waste paper. In the packaging paper industry, the raw materials for papermaking are mainly recycled boxboard. Due to the lack of high-quality long-fiber raw materials, in order to ensure the strength of paper, the starch surface sizing process is generally adopted in China, and the amount of starch used is increasing, generally 20-50kg / ton of paper, and some papermaking enterprises in the north have exceeded 60-70kg / ton of paper. Papermaking enterprises generally use industrial starch or edible starch as surface sizing raw materials, and the source of starch is mainly domestic edible corn starch and imported cassava starch, which are important food and industrial raw materials. Since the prices of these two starches have been getting higher and higher in the past three years, the higher starch dosage has not only increased the production cost of papermaking, but also increased the wastewater COD treatment cost due to the degradation or loss of some starch into papermaking wastewater.

[0003] Therefore, how to reasonably use starch for surface sizing, reduce production costs and wastewater treatment costs, and save food and industrial raw materials have important economic and social benefits. However, the existing starch detection methods still have certain defects, such as:

[0004] The invention announcement number CN113267524B discloses a method for detecting starch-based plastic components. The method uses solid nuclear magnetic resonance technology to achieve qualitative identification of the components of starch-based plastic samples. It does not require complicated pre-treatment operations or the addition of other chemical solvents. The detection is convenient, fast and pollution-free. When determining, the starch content can be obtained by simply calculating the integrated area ratio of the tested starch-based plastic sample in combination with a standard curve. The method is convenient and fast, and can achieve starch content detection of large batches of samples.

[0005] In the above-mentioned document, in the process of detecting starch content, this detection method needs to detect the starch content inside the plastic through a solid nuclear magnetic resonance instrument to obtain the spectrum of the sample, and then calculate the different starch contents inside the different samples. However, in the process of detecting the starch content on the surface of the sample, this detection method is difficult to implement and needs to be detected by other methods.

[0006] In response to the above problems, it is urgent to carry out innovative designs based on the original detection methods. Summary of the invention

[0007] The object of the present invention is to provide a method for detecting the starch content of boxboard paper to solve the problems raised in the above background technology.

[0008] To achieve the above object, the present invention provides the following technical solution: a method for detecting the starch content of boxboard paper, comprising the following steps:

[0009] S1: Qualitative detection of starch content on the surface of boxboard

[0010] First, use the colorimeter CA60 and the whiteness meter ZB-B to test the whiteness and L value of each paper sample, and make a record. Then, according to the principle that iodine turns blue when it meets starch, spray the paper sample with 0.5% iodine solution and dry it. Observe whether the paper sample changes color, and the difference in whiteness and L value of the paper sample after the color change.

[0011] S2: Quantitative detection of the amount of starch coated on the surface of boxboard

[0012] Place the sample in a constant temperature water bath at 90 degrees Celsius and soak for 2 hours. Take it out and put it in an electric constant temperature air drying oven to dry. Then weigh it on an electronic balance and record it. Repeat this process until the sample mass stops changing.

[0013] S3: Detection of total starch content in boxboard

[0014] Place the paper sample in 2,000 ml of pure water, soak for two hours, then place it in the decomposition machine to break it up, and dye the filtrate with 2% iodine solution, and finally detect the wavelength of the filtrate with a visible spectrophotometer;

[0015] S4: Detection of internal starch content of containerboard

[0016] The outer side of the paper sample is dyed with 0.5% iodine solution for observation. After the paper sample is dried and there is no color change on the surface, the paper sample can be crushed and the filtrate can be filtered out. The wavelength of the filtrate is detected by a photometer.

[0017] After the outside of the paper sample is dyed with iodine solution, its surface is found to have obvious color change. Then the paper sample can be placed in a defragmenter to break it up and test the overall starch content of the paper sample. Then the paper sample is soaked in a constant temperature water bath and then placed in an electric constant temperature blower drying oven to dry. This process is repeated to detect the starch content on the surface of the paper sample.

[0018] Preferably, in the step (1), during the qualitative detection of starch content coated on the surface of boxboard, each paper sample of the same variety is grouped as a group, and the number of samples of each paper sample is 3. A circle with an area of ​​100 square centimeters is cut from each paper sample with a quantitative sampler. Using three different materials, namely kraft paper, boxboard, and high-wafer paper, as paper samples can improve the accuracy of the verification of this method.

[0019] Preferably, in the step (1), during the qualitative detection of starch content coated on the surface of the boxboard, the L value and whiteness of each paper sample are detected using a colorimeter CA60 and a whiteness meter ZB-B, and the paper samples are marked and numbered. When the whiteness meter ZB-B is used for detection, the wavelength of light is adjusted to R457 nanometers. By detecting the wavelength of the whiteness meter, the detection effect of the whiteness meter can be improved.

[0020] Preferably, in the step (2), during the quantitative detection of the amount of starch coated on the surface of the boxboard, the amount of starch applied on one side of the surface = (absolute dry weight of the paper sheet before soaking - absolute dry weight of the paper sheet after soaking) ÷ paper sample area ÷ 0.9 ÷ 2. The accuracy of the detection result can be effectively improved through precise calculation.

[0021] Preferably, in the step (2), during the quantitative detection of the amount of starch coated on the surface of the boxboard, for the convenience of calculation, the sample needs to be cut into A4 paper samples, 30 cm long and 20 cm wide.

[0022] Preferably, in the step (3), during the detection of the total starch content of the boxboard, approximately 1 gram of analytically pure starch is accurately weighed to an accuracy of 0.001 gram during the preparation of the starch standard solution and added to 1000 ml of laboratory pure water.

[0023] Preferably, in the step (3), during the detection of the total starch content of the boxboard, a certain amount of paper sample approximately equivalent to 30 grams of absolute dry weight is weighed, 2000 ml of pure water at a temperature of about 80 degrees Celsius is added, and after soaking for two hours, it is poured into a deagglomerator, and the speed of the deagglomerator is adjusted to 3000 revolutions per minute, and the deagglomerator is deagglomerated at 30,000 revolutions. Placing the paper sample in high-temperature pure water facilitates rapid softening and decomposition of the paper sample, and can improve the effect of the deagglomerator on crushing the paper sample.

[0024] Preferably, in the step (3), during the detection of the total starch content of the boxboard, the pulp sample after decomposition is filtered through an 80-mesh filter, the filtrate is dyed by adding an excess of 2% iodine solution, and then placed in an L9 UV-visible spectrophotometer to detect the absorbance A, and the filtrate is filtered through an 80-mesh filter to obtain a pure filtrate, which facilitates the subsequent dyeing.

[0025] Preferably, in the step (3), during the detection of the total starch content of the boxboard, the internal starch content of the board is equal to the total starch content minus the surface coating starch content.

[0026] Compared with the prior art, the present invention has the following beneficial effects:

[0027] 1. The method for detecting starch content of boxboard paper uses a plurality of paper samples of different materials for comparison in step 1, so that the paper samples with larger differences in whiteness and L value have higher surface sizing starch content, and vice versa. The same variety and quantity can be compared with each other, so as to qualitatively and intuitively judge the difference in surface sizing starch content of paper samples of different manufacturers and varieties;

[0028] 2. The method for detecting the starch content of boxboard paper, in step 2, by repeatedly soaking and drying the paper sample, the starch on the surface of the paper sample can be fully discharged, so that the method can accurately detect the starch content on the surface of the paper sample;

[0029] 3. The method for detecting the starch content of the boxboard paper comprises the following steps: in step 3, the paper sample is placed in pure water for soaking, and then crushed and ground by a decomposition device, so as to break up the paper sample for easy dilution and decomposition of starch, and then the pure water is filtered and iodine solution is added to the filtrate and the absorbance of the filtrate is detected, so as to accurately detect the overall starch content of the paper sample;

[0030] 4. The method for detecting starch content of boxboard can quickly determine whether there is starch on the surface of boxboard, so as to determine whether over-coating, surface sizing, or spray sizing processes are used in the production process. The total starch content, surface coating starch content and internal starch content can be directly or indirectly detected through a variety of detection schemes. DETAILED DESCRIPTION

[0031] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0032] The present invention provides a technical solution: a method for detecting starch content of boxboard. The present invention utilizes the principle that starch is dissolved by heating water and turns blue when it is exposed to iodine. The dissolution method and before and after iodine dyeing are used. Instruments such as Ci6X X-Rite spectrophotometer, whiteness meter, and L9 ultraviolet-visible spectrophotometer are used to detect and compare brightness, whiteness, and absorbance. The surface starch content, starch content in pulp, and total starch content of corrugated paper, kraft paper, boxboard, and recycled waste boxboard sold on the market are qualitatively and quantitatively analyzed, and the surface starch content and starch content in pulp are reversely inferred. The first purpose is to master the process status of mainstream products on the market, reasonably adjust the starch sizing process of the boxboard surface of our company, reduce the amount of starch, and thus provide a basis for reducing production costs.

[0033] include:

[0034] S1: Qualitative detection of starch content on the surface of boxboard (dyeing method)

[0035] First, use the colorimeter CA60 and the whiteness meter ZB-B to test the whiteness and L value of each paper sample, and make a record. Then, according to the principle that iodine turns blue when it meets starch, spray the paper sample with 0.5% iodine solution and dry it. Observe whether the paper sample changes color, and the difference in whiteness and L value of the paper sample after the color change.

[0036] In step (1), during the qualitative detection of the starch content coated on the surface of the boxboard, each paper sample of the same variety is grouped together, and the number of samples of each paper sample is 3. A circle with an area of ​​100 square centimeters is cut from each paper sample using a quantitative sampler. During the qualitative detection of the starch content coated on the surface of the boxboard, the L value and whiteness of each paper sample are detected using a colorimeter CA60 and a whiteness meter ZB-B, respectively, and the samples are marked and numbered. When using the whiteness meter ZB-B for detection, the wavelength of light is adjusted to R457 nanometers.

[0037] 1. Each paper sample of the same type, such as kraft paper, boxboard and high-wafer paper, is grouped into one group. The number of samples for each paper sample is 3. A circle with an area of ​​100 square centimeters is cut from each paper sample using a quantitative sampler.

[0038] 2. Use colorimeter CA60 and whiteness meter ZB-B to test the whiteness and L value of each paper sample, and mark and number them. When using whiteness meter ZB-B for testing, adjust the wavelength of light to R457nm.

[0039] 3. Based on the principle that iodine turns blue when it meets starch, spray the remaining two paper samples of each variety with 0.5% iodine solution for dyeing. The amount of iodine solution needs to reach saturation until the color no longer darkens.

[0040] 4. Let the paper samples dry, then use the colorimeter CA60 and the whiteness meter ZB-B to test the L value and whiteness of each paper sample, and mark and number them. When using the whiteness meter ZB-B for testing, adjust the wavelength of light to R457nm.

[0041] 5. If the paper sample does not turn blue after dyeing, it means that there is no starch on the surface of the paper sample of this variety. If the paper sample turns blue after dyeing, calculate the difference in whiteness and L value before and after dyeing. Whiteness difference (R457nm) = whiteness before dyeing - whiteness after dyeing, L value difference (brightness) = L value before dyeing - L value after dyeing.

[0042] S2: Quantitative detection of the amount of starch coated on the surface of boxboard (dissolution method)

[0043] Place the sample in a constant temperature water bath at 90 degrees Celsius and soak for 2 hours. Take it out and put it in an electric constant temperature air drying oven to dry. Then weigh it on an electronic balance and record it. Repeat this process until the sample mass stops changing.

[0044] In step (2), during the quantitative detection of the amount of starch coated on the surface of the boxboard, the amount of starch applied on one side of the surface = (absolute dry weight of the paper sheet before soaking - absolute dry weight of the paper sheet after soaking) ÷ paper sample area ÷ 0.9 ÷ 2. In step (2), during the quantitative detection of the amount of starch coated on the surface of the boxboard, in order to facilitate calculation, the sample needs to be cut into A4 paper samples, 30 cm long and 20 cm wide.

[0045] 1. The sample needs to be cut into A4 paper, 30 cm long and 20 cm wide;

[0046] 2. Put the cut samples into an electric constant temperature air drying oven, wait until the moisture is completely removed, bake the samples until constant weight is reached, take them out, place them on an electronic balance, weigh them and record them;

[0047] Heat the constant temperature water bath to 90 degrees Celsius and keep it warm. Put the dried sample in and soak for 2 hours. Then take it out and put it in the electric constant temperature blast drying oven. When the moisture is completely removed, bake the sample to constant weight, take it out, put it on the electronic balance to weigh and record it.

[0048] 3. Repeat the previous step until the sample weight no longer changes.

[0049] 4. The amount of starch applied on one side (air-dried starch) (g / m 2 )

[0050] The amount of starch applied on one side = (absolute dry weight of paper before soaking - absolute dry weight of paper after soaking) ÷ paper sample area ÷ 0.9 ÷ 2

[0051] Total sizing starch amount (air-dried starch) (g / m 2 )

[0052] Total sizing starch amount = single-sided surface sizing starch amount × 25.4.3 tons of paper starch unit consumption (air-dried starch) kg / ton of paper

[0053] Starch consumption per ton of paper = (total starch amount × ton of paper area) ÷ 1000

[0054] S3: Detection of total starch content of boxboard (spectrophotometry)

[0055] Place the paper sample in 2,000 ml of pure water, soak for two hours, then place it in the decomposition machine to break it up, and dye the filtrate with 2% iodine solution, and finally detect the wavelength of the filtrate with a visible spectrophotometer;

[0056] In step (3), during the detection of the total starch content of the boxboard, during the preparation of the starch standard solution, about 1 gram of analytical pure starch is accurately weighed to an accuracy of 0.001 gram and added to 1000 ml of laboratory pure water. During the detection of the total starch content of the boxboard, a certain amount of paper sample approximately equivalent to 30 grams of absolute dry weight is weighed, 2000 ml of pure water at a temperature of about 80 degrees Celsius is added, and after soaking for two hours, it is poured into a deagglomerator, and the deagglomerator is adjusted to 3000 revolutions per minute and the deagglomeration is performed at 30,000 revolutions. During the detection of the total starch content of the boxboard, the deagglomerated pulp sample is filtered with an 80-mesh filter, and the filtrate is dyed with an excess of 2% iodine solution, and then placed in an L9 UV-visible spectrophotometer to detect the absorbance A. During the detection of the total starch content of the boxboard, the internal starch content of the board is equal to the total starch content minus the surface coating starch content.

[0057] 1. Accurately weigh about 1 gram (accurate to 0.001 gram) of analytical grade starch from 2% iodine solution, 1% starch solution, 0.1% starch solution, etc., and add it to 1000 ml of laboratory pure water;

[0058] 2. Boil, cool, and dilute to (0.011, 0.012, 0.013, 0.014, 0.015, 0.016, 0.017, 0.018, 0.019, 0.02); (0.021, 0.022, 0.023, 0.024, 0.025, 0.026, 0.027, 0.028, 0.029, 0.03); (0.001, 0.002, 0.003, 0.004, 0.005, 0.006, 0.007, 0.008, 0.009, 0.01 (%), then add 2% iodine solution for dyeing;

[0059] 3. Use L9 UV-Vis spectrophotometer to detect absorbance A and make a standard comparison table (or a curve chart) of the corresponding values ​​of starch content and absorbance;

[0060] Weigh a certain amount of paper sample equivalent to 30 grams of absolute dry weight, add 2000ml of pure water at a temperature of about 80℃, soak for 2 hours, then pour it into the deagglomerator, adjust the speed to 3000 rpm, and deagglomerate at 30000 rpm;

[0061] 4. Filter the pulp sample after debonding with a 80-mesh filter, add an excess of 2% iodine solution to the filtrate for dyeing, and then put it into the L9 UV-visible spectrophotometer to detect the absorbance A. The wavelength of the spectrophotometer is 570-620nm, and the reference liquid is pure water. If the absorbance A is not within the range, it needs to be diluted with an appropriate multiple and retested;

[0062] 5. Total starch content = corresponding starch content in the absorbance comparison table × dilution multiple

[0063] Total starch content per ton of paper = (1000 ÷ paper sample weight) × starch content

[0064] S4: Detection of internal starch content of containerboard

[0065] The outer side of the paper sample is dyed with 0.5% iodine solution for observation. After the paper sample is dried and there is no color change on the surface, the paper sample can be crushed and the filtrate can be filtered out. The wavelength of the filtrate is detected by a photometer.

[0066] After the outside of the paper sample is dyed with iodine solution, its surface is found to have obvious color change. Then the paper sample can be placed in a defragmenter to break it up and test the overall starch content of the paper sample. Then the paper sample is soaked in a constant temperature water bath and then placed in an electric constant temperature blower drying oven to dry. This process is repeated to detect the starch content on the surface of the paper sample.

[0067] For products without starch coating on the surface but with starch added in the slurry during the production process, it can be detected by the following methods:

[0068] 1. If the surface is not coated with starch by the dyeing method, it can be detected directly by the spectrophotometry method in step (3).

[0069] 2. If the surface is coated with starch by the dyeing method, the total starch content is first detected by step (3) - spectrophotometry, and then the surface coating starch content is detected by step (2) - dissolution method. The difference between the two is the internal starch content, which is calculated as follows:

[0070] Internal starch content of boxboard = total starch content (spectrophotometric method) - surface coating starch content (dissolution method)

[0071] In the description of the present invention, unless otherwise specified, "plurality" means two or more than two; the terms "upper", "lower", "left", "right", "inner", "outer", "front end", "rear end", "head", "tail" and the like indicate positions or positional relationships based on the positions or positional relationships shown, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific position, be constructed and operated in a specific position, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", "third" and the like are used for descriptive purposes only and cannot be understood as indicating or implying relative importance.

[0072] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "connected" and "connection" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0073] The contents not described in detail in this specification belong to the prior art known to professional and technical personnel in this field.

[0074] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for detecting starch content in boxboard, characterized in that: The following steps are involved: S1: Qualitative detection of starch content on the surface of boxboard First, use the colorimeter CA60 and the whiteness meter ZB-B to test the whiteness and L value of each paper sample, and make a record. Then, according to the principle that iodine turns blue when it meets starch, spray the paper sample with 0.5% iodine solution and dry it. Observe whether the paper sample changes color, and the difference in whiteness and L value of the paper sample after the color change. S2: Quantitative detection of the amount of starch coated on the surface of boxboard Place the sample in a constant temperature water bath at 90 degrees Celsius and soak for 2 hours. Take it out and put it in an electric constant temperature air drying oven to dry. Then weigh it on an electronic balance and record it. Repeat this process until the sample mass stops changing. S3: Detection of total starch content in boxboard Place the paper sample in 2,000 ml of pure water, soak for two hours, then place it in the decomposition machine to break it up, and dye the filtrate with 2% iodine solution, and finally detect the wavelength of the filtrate with a visible spectrophotometer; S4: Detection of internal starch content of containerboard The outer side of the paper sample is dyed with 0.5% iodine solution for observation. After the paper sample is dried and there is no color change on the surface, the paper sample can be crushed and the filtrate can be filtered out. The wavelength of the filtrate is detected by a photometer. After the outside of the paper sample is dyed with iodine solution, its surface is found to have obvious color change. Then the paper sample can be placed in a defragmenter to break it up and test the overall starch content of the paper sample. Then the paper sample is soaked in a constant temperature water bath and then placed in an electric constant temperature blower drying oven to dry. This process is repeated to detect the starch content on the surface of the paper sample.

2. The method for detecting starch content in boxboard according to claim 1, characterized in that: In the step (1), during the qualitative detection of starch content coated on the surface of boxboard, each paper sample of the same variety is grouped together, and the number of samples of each paper sample is 3. A circle with an area of ​​100 square centimeters is cut from each paper sample using a quantitative sampler.

3. The method for detecting starch content in boxboard according to claim 1, characterized in that: In the step (1), during the qualitative detection of the starch content coated on the surface of the boxboard, the L value and whiteness of each paper sample are detected using a colorimeter CA60 and a whiteness meter ZB-B, and the paper samples are marked and numbered. When the whiteness meter ZB-B is used for detection, the wavelength of light is adjusted to R457 nanometers.

4. The method for detecting starch content in boxboard according to claim 1, characterized in that: In the step (2), during the quantitative detection of the amount of starch coated on the surface of the boxboard, the amount of starch applied on one side of the surface = (absolute dry weight of the paper sheet before soaking - absolute dry weight of the paper sheet after soaking) ÷ paper sample area ÷ 0.9 ÷ 2.

5. The method for detecting starch content in boxboard according to claim 1, characterized in that: In the step (2), during the quantitative detection of the amount of starch coated on the surface of the boxboard, for the convenience of calculation, the sample needs to be cut into A4 paper samples, 30 cm long and 20 cm wide.

6. The method for detecting starch content in boxboard according to claim 1, characterized in that: In the step (3), during the detection of the total starch content of the boxboard, approximately 1 gram of analytically pure starch is accurately weighed to an accuracy of 0.001 gram during the preparation of the starch standard solution, and added to 1000 ml of laboratory pure water.

7. The method for detecting starch content in boxboard according to claim 1, characterized in that: In the step (3), during the detection of the total starch content of the boxboard, a certain amount of paper sample approximately equivalent to an absolute dry weight of 30 grams is weighed, 2000 ml of pure water at a temperature of about 80 degrees Celsius is added, and after soaking for two hours, the sample is poured into a deagglomerator, and the speed of the deagglomerator is adjusted to 3000 revolutions per minute, and the deagglomeration is performed at 30,000 revolutions.

8. The method for detecting starch content in boxboard according to claim 1, characterized in that: In the step (3), during the detection of the total starch content of the boxboard, the pulp sample after decomposition is filtered through an 80-mesh filter, and the filtrate is dyed by adding an excess of 2% iodine solution, and then placed in an L9 UV-visible spectrophotometer to detect the absorbance A.

9. The method for detecting starch content in boxboard according to claim 1, characterized in that: In the step (3), during the detection of the total starch content of the boxboard, the internal starch content of the board is equal to the total starch content minus the surface coating starch content.