JP2007271545A - Method for measuring deposition degree of foreign substance - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a measuring method for predicting deposition of foreign substance, especially the deposition degree of the scale, pitch of adhesive foreign substance, exerting a large influence on machine operability or product quality, in a manufacturing process of pulp and paper. <P>SOLUTION: In the manufacturing process of pulp and paper, the deposition degree of the foreign substance in the process is measured, by using a microbalance having a quartz oscillator, preferably a microbalance capable of measuring frequency change (Δf) and dissipation value (ΔD) due to the adherence of the foreign substances on the quartz oscillator surface. Furthermore by measuring the viscoelasticity of the foreign substance, it can be also determined whether the deposited foreign substance is a hard material or a soft material. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a method for measuring the degree of foreign matter deposition occurring at various places in the pulp and paper manufacturing process. More specifically, it can be dealt with early by installing microbalances with crystal units in various parts of the pulp and paper manufacturing process, and measuring the degree of foreign matter deposition from the information obtained from the device. About how to become.

In the pulp and paper manufacturing process, foreign matter deposits, particularly scale and pitch deposits, often occur, greatly affecting machine operability and product quality.
[scale]
For example, in the kraft pulping process, oxalate ions and calcium ions are eluted from wood chips during cooking. Also, carbonate ions are present in the cooking liquor. When these ions react during cooking to produce calcium oxalate or calcium carbonate and precipitate in a later step, they may adhere to the digester, piping, strainer, etc. to form a scale. If the scale adheres to the strainer, problems such as a decrease in thermal efficiency and uneven pulp quality occur.

  In the regenerated pulp manufacturing process, calcium carbonate-derived calcium ions contained in the waste paper are combined with sulfate ions derived from sulfate bands and oxalate ions derived from natural products to form a sulfuric acid scale and an oxalic acid scale. In addition, the sulfuric acid band-derived alumina contained in the waste paper elutes as aluminate by alkali treatment, and then precipitates as aluminum hydroxide due to the lowering of pH, resulting in silicic acid derived from sodium silicate used as a deinking chemical. In some cases, ions are taken into an aluminum silicate scale. When these scales adhere to an apparatus or the like, problems such as operability and uneven pulp quality occur.

  The same applies to the manufacturing process of paper.Sulfuric acid bands are used to fix sizing agents, dyes and other chemicals to fibers, or to improve yield and drainage. Generate a scale. Or the calcium ion derived from calcium carbonate couple | bonds with a sulfate ion and an oxalate ion similarly to the above, and becomes a sulfuric acid scale and an oxalic acid scale. If this scale adheres to, for example, felt or the like, unevenness of water squeezing occurs at the felt site, resulting in poor texture or running out of paper, causing trouble.

  Regarding these scales, troubles are avoided by washing with acid or alkali for a certain period of time. Alternatively, scale inhibitors such as polyphosphates, acrylic polymers, and various phosphonic acids are added in advance in the process.

  The type and amount of the scale inhibitor are added according to the results of water quality analysis and sampling from the bypass line as needed, and after checking the scale adhesion state.

As an example of a method for examining the scale adhesion state, a method for measuring the weight of a scale adhered to a metal wire is disclosed in Japanese Patent Laid-Open No. 7-159305 (Patent Document 1). A precision of about 1 / 400,000 to 800,000 is required, so very precise work is required. Furthermore, since the process is likely to fluctuate, it cannot be said that the measured result necessarily reflects the current state, and the countermeasure will be followed.
[Pitch / adhesive foreign matter]
As with the scale, pitch and adhesive foreign matter also cause major troubles in the pulp and paper manufacturing process.

  For example, mechanical pulps manufactured by mechanical processing are extracted components such as triglyceride and abietic acid, and used paper pulp is an adhesive derived from used waste paper, adhesive tape, magazine back glue, vinyl tape, and other acrylics. Non-water-soluble adhesives mainly composed of organic substances derived from substances such as adhesives, vinyl acetates, hot melts and the like (herein referred to as adhesive foreign matter) and additive chemicals used in pulp and paper manufacturing processes A wide variety of materials, such as those shown, cause pitch.

  These pitch components are usually dispersed in a colloidal form in the papermaking process slurry, but their colloidal state is destroyed and destabilized by large shearing force, rapid pH change, addition of sulfuric acid band, etc. Incorporating and depositing contaminating ions, inorganic substances, and organic substances, or agglomerating and coarsening. The coarsened pitch adheres to pipes, wires, etc., or reattaches to pulp or paper, thereby causing a decrease in quality due to paper defects, a paper breakage, and a decrease in productivity.

  In recent years, since the process has been closed from the viewpoint of environmental considerations, the problem of pitch has increased and has become complicated. Furthermore, since the use of recycled pulp is increasing from the viewpoint of environmental considerations and cost reduction, the amount of pitch mixed in the pulp and paper manufacturing process is the amount of adhesive foreign matter mixed in the recycled pulp. It can be said that it greatly depends on the quantity.

  In taking measures against the above pitch troubles, it is very important to grasp the quantity and properties of adhesive foreign matters mixed in the pulp and paper manufacturing process.

  By the way, the adhesive foreign substances are classified into coarse adhesive foreign substances that do not pass through a screen having a slit width of 100 μm and fine adhesive foreign substances that pass through the screen. A method for evaluating coarse adhesive foreign matter has been established to some extent, and it is known that reliable data can be obtained (Non-Patent Document 1).

  On the other hand, the evaluation method for fine adhesive foreign matter is extremely difficult due to its properties, and although there are many reports, it has not been established yet. For example, there is an extraction method using an organic solvent as a method for evaluating fine adhesive foreign matter. However, this method measures not only adhesive foreign matter but also the amount of oil derived from the ink vehicle and other solvent extracts not having adhesiveness derived from the surfactant. HAK LAE LEE and others have investigated deposits in actual manufacturing processes, not model experiments, and reported that adhesive-derived components accounted for less than 5% of solvent extracts. (Non-Patent Document 2). For this reason, it is difficult to say that such an extraction method accurately measures the amount of adhesive foreign matter. Furthermore, it takes a very long time to measure including the extraction time.

  In addition, methods for measuring the amount of adhesion to hydrophobic films and metal wires, and methods for measuring and obtaining COD and TOC have been proposed. Because of the large error caused by other substances such as COD and TOC, the adhesiveness cannot be evaluated by the COD and TOC methods. Yes (Non-Patent Documents 3 and 4).

JP 7-159305 A Mahendra R. Doshi et.al, Comparison of Macrostickies Measurement Methods, Progress in Paper Recycling Vol. 12, No. 3, May 2003, 34-4 Hak Lae Lee, Jong Min Kim, Quantification of Macro and Micro Stickies and Their Control by Flotation in OCC Recycling Process, Appita Journal Vol.59, No.1,31-36,2006 Mahendra R. Doshi et.al, Comparison of Microstickies Measurement Methods PartI, Progress in Paper Recycling Vol. 12, No. 4, 35-42, 2003 Mahendra R. Doshi et.al, Comparison of Microstickies Measurement Methods Part II, Progress in Paper Recycling Vol. 13, No. 1, 44-53, 2003

  Then, an object of this invention is to provide the method of measuring the deposition degree of the foreign material generate | occur | produced in the manufacturing process of a pulp and paper by using the microbalance which has a crystal oscillator.

  The present inventors have been able to measure the weight dissipation at a molecular level of a microbalance having a quartz crystal resonator, to be able to use it on-line because it can be measured in real time, and to measure energy dissipation. Focusing on the fact that it is possible to measure the viscoelasticity and film thickness of substances by using a device that can be used. It was found that it is possible to predict the degree of deposition of foreign matter.

  ADVANTAGE OF THE INVENTION According to this invention, it is possible to measure correctly the deposition degree of foreign materials, such as an adhesion foreign material, a pitch, and a scale which generate | occur | produce in the manufacturing process of a pulp and paper. Furthermore, it is possible to determine whether the deposited foreign matter is a hard substance or a soft substance by measuring the viscoelasticity of the foreign substance.

  The pulp manufacturing process in the present invention refers to a process of taking out pulp (fibrin) from chips, logs, waste paper, and dry sheets.

  In the present invention, the paper manufacturing process refers to a process for forming pulp into a sheet, and includes all processes including a wet end process, a pressing process, a dryer process, a calendar process, a wastewater treatment process, and a process for treating these waters. Point to. The wet end process in the present invention may be a process for producing paper using a known paper machine such as a long net paper machine, a twin wire paper machine, or a cylindrical paper machine, and is not limited thereto. Further, it may be a single-layer paper or a multilayer paper having two or more layers. In addition, the paper to be made may contain a filler. As the filler, known fillers such as white carbon, talc, kaolin, clay, heavy calcium carbonate, light calcium carbonate, titanium oxide, and synthetic resin filler are used. can do. Furthermore, it may contain a sulfuric acid band, a sizing agent, a paper strength enhancer, a yield improver, a drainage improver, a colorant, a dye, an antifoaming agent and the like as necessary.

  Examples of the paper produced in the paper production process of the present invention include printing paper, newsprint, information recording paper, processed paper, sanitary paper, and the like, but are not limited thereto. More specifically, the information paper includes electrophotographic transfer paper, ink jet recording paper, foam paper, thermal recording paper, pressure sensitive recording paper, and the like. More specifically, the processed paper includes release paper base paper, laminated board base paper, molding base paper, and the like. More specifically, sanitary paper includes tissue paper, toilet paper, paper towels, and the like. Also included are paperboards such as liners and cardboard.

  The microbalance having a crystal resonator in the present invention may be any device as long as it can measure a minute weight change occurring on the surface of the resonator using the piezoelectric effect of the crystal resonator. As a microbalance having a quartz crystal resonator capable of measuring energy dissipation, for example, there is an intermolecular interaction quantitative measurement device (model name: QCM-D300) manufactured by Q-sence. The measurement principle of the apparatus is as follows.

  When an alternating electric field is applied to the crystal unit, the crystal of the crystal is distorted. At this time, the crystal vibrates very regularly. When the sample adheres to the surface of the crystal unit, the frequency changes. Since the amount of change in the frequency is proportional to the mass of the attached film, it is possible to measure the mass of the material adhering to the surface of the crystal unit. In addition, when a highly viscous sample is attached, the oscillator decays faster than when a low-viscosity substance is attached, so that the viscoelasticity (hardness) of the substance attached to the quartz resonator surface can be measured. . As described above, when the apparatus is used, it is possible to simultaneously measure not only the weight change of the adhered substance but also the viscoelasticity of the adhered substance.

Specifically, the frequency change (Δf) and the dissipation value (ΔD) are measured by the apparatus. Since the relationship of the following formula 1 is established between the frequency change Δf and the weight change Δm in the wet state, Δf indicates the weight of the foreign matter attached to the surface of the crystal resonator in the wet state. It can be said.
Δf = constant × Δm (Formula 1)
Further, Δf can be converted into a weight change (Δm) in a wet state of a foreign substance adhering to the surface of the crystal resonator by using the following Sauerbrey equation (the following equation 2). In the above apparatus, four levels of frequencies of 5, 15, 25, and 35 MHz are automatically switched, and each Δf is measured. Δf in Equation 2 is 1 for each Δf measured at the four levels. Use the value after dividing by 3, 5, 7 (converted to the value at 5 MHz).
Δm = −17.7 (ng · cm ⁻² · Hz ⁻¹ ) · Δf (Hz) (Formula 2)
Further, the dissipation value ΔD is obtained using the following equation (Equation 3 below) from energy dissipating at one amplitude (E _dissipated ) and stored energy in the amplitude system (E _stored ).
ΔD = E _dissipated / 2πE _stored (Formula 3)
ΔD is a value obtained when the vibration of the crystal unit is attenuated more rapidly when a material having high viscoelasticity adheres to the surface of the crystal unit than when a material having low viscoelasticity adheres. That is, if Δf is the same value and ΔD is high, it is considered that a substance having a large film thickness and a high viscosity is attached.

  When the sample contains a long fiber or a foreign substance having a large particle size, it is preferable to perform the measurement after pre-treating the sample. As a pretreatment method, a method such as filtration using a general sieve is conceivable, but the solid content is 5% by weight or less, and the content of long fibers of the pulp is based on the total solid content. Any method may be used as long as it can collect a filtrate of 50% by weight or less. Here, the long fiber content of the pulp refers to pulp fibers remaining on the sieve when separated by a 150 mesh sieve.

  In the present invention, foreign substances refer to all substances that are generated in the pulp and paper manufacturing process and adversely affect product quality and operability. For example, metal salt scales such as calcium oxalate, calcium sulfate, calcium carbonate, aluminum silicate, triglycerides derived from mechanical pulp, natural pitch derived from resins such as abietic acid, additive chemicals used in pulp and paper manufacturing processes, White pitch consisting of hydrophobic substances mainly composed of organic substances such as latex derived from waste paper, adhesives derived from waste paper, adhesive tape, magazine back glue, adhesives such as acrylic, vinyl acetate, hot melt, etc. Refers to a foreign object.

  The deposition of foreign matter in the present invention means that foreign matter adheres to and accumulates on all substances such as pipes, nets, and devices in the pulp and paper manufacturing process. With regard to adhesion, for example, in addition to adhering sticky substances as they are, substances suspended in water cause precipitation, or dispersed substances become unstable due to pH shock or temperature change, Forming a deposit. In addition, deposition refers to the amount of substance that adheres to the sensor per certain time.

  In the present invention, the process water means water used or generated in the pulp and paper manufacturing process, and the solid content is usually 5% by weight or less, and the content of the long fiber content of the pulp is the total solid content. On the other hand, it is 50% by weight or less. Here, the long fiber content of the pulp refers to pulp fibers remaining on the sieve when separated by a 150 mesh sieve. Specifically, as process water, white water generated or used in the pulp and / or paper manufacturing process, irrigation water, industrial water, reused water, industrial water, water after washing of a washing machine, (E.g. DNT washers, extractors, screw presses, etc.), flotation or rejection of floaters, scum and accept of pressurized flotation devices, shower water, washing water such as felt, diluted water for raw materials, Water after separation treatment such as flotation separation, foam separation, sedimentation separation, membrane separation, centrifugation, and flocculation separation.

In the present invention, when the object to be measured is a pitch component or an adhesive foreign material, it is preferable that the crystal resonator is coated with a hydrophobic substance. This means that the surface of the crystal unit is coated in order to easily attach a hydrophobic substance such as a pitch component in the process to the surface of the crystal unit. As a hydrophobic substance to be coated, an organic substance having a surface free energy in the range of ^{20 to} 50 mJ / m ² , preferably 30 to 40 mJ / m ² , such as a polystyrene-based resin, polyethylene, etc. Examples thereof include, but are not particularly limited, as long as they are hydrophobic substances.

  With the online water-squeezing device in the present invention, for example, a filtrate collecting device (trade name: REX-100S-ST) manufactured by Koei Kogyo Co., Ltd. can be used. It is preferably 1% by weight or less, and is not particularly limited as long as the content of the long fiber content of the pulp contained in the filtrate can be adjusted to 50% by weight or less with respect to the total solid content.

  The present invention can also be measured online by a flow as shown in FIG. 1 incorporating the online water pumping device. In addition, for example, the Q-sence 4-channel intermolecular interaction analyzer (model Q-SENSE E4) can be used. By combining the flow shown in FIG. 2, it is possible to simultaneously measure the chemical treatment effect (A-B comparison) in the actual machine process and the separation effect (B-C comparison) in the separation device. .

  Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to the examples.

[Examples 1 to 4]
Rough selection process of factory A using high-quality waste paper as a measurement sample (Process I) White water and fine selection process (Process II) Rough selection process of Factory B using white water and newspaper waste paper (Process III) A filtrate obtained by filtering white water and white water through a 500 mesh sieve was used. Q-sence's intermolecular interaction quantitative measurement device (model QCM-D300) is used to measure the degree of foreign matter deposition using a microbalance with a crystal resonator, and the surface of the crystal resonator is used as a measurement sensor. The one coated with stainless steel was used. The measurement was performed at 25 ± 0.5 ° C., and 0.5 ml of the sample was poured into the reaction cell and then allowed to stand for 15 minutes to monitor the amount of foreign matter adhering to the surface of the crystal unit. After 15 minutes, the operation of pouring distilled water into the reaction cell and washing for 3 minutes was repeated twice, and the amount of adhesion after washing twice was taken as the measured value. FIG. 3 shows an example of measurement. In addition, the measured value with a frequency of 25 MHz was used for the frequency change (Δf) and the dissipation value (ΔD). The results are shown in Table 1.

  Among Examples 1 to 4, it has been known that, particularly with respect to the steps shown in Example 2, instrument contamination due to deposits is a problem. As described above, Δf indicates the degree of deposition (attachment amount) of foreign matter, but it can be seen that Δf in Example 2 is clearly larger than Examples 1, 3, and 4. From this, it is considered that a trouble due to the pitch of the actual process can be predicted by using the apparatus. Further, when D / f indicating the viscoelasticity of the deposit is calculated, it is presumed that the presence ratio of the soft substance is high, that is, there are a lot of sticking foreign matters and pitch components because it is the largest in Example 2.

[Examples 5 to 6]
As a measurement sample, a filtrate obtained by filtering the raw material before and after the flotation separation device (F / T) in the used paper recycling process with a 500 mesh sieve was used. The measurement method was carried out under the same conditions as in Example 1 except that a quartz crystal unit whose surface was coated with polystyrene was used.

[Examples 7 to 8]
It carried out similarly to Example 5 except having added the pitch control agent to the measurement sample.

[Comparative Examples 1-2]
The measurement sample used was the same as in Example 5. However, in this comparative example, the filtrate filtered with a 500 mesh sieve was not used, but so-called whole pulp was used. In the measurement method, after adjusting the sample to pH 2, toluene was added and osmotic extraction was performed for 5 minutes. After extraction, the toluene layer was evaporated to dryness, and then the absolute dry weight was measured. Then, the amount of extract was computed from the following formula | equation.
Extraction amount (%) = toluene extraction weight / solid content weight

[Comparative Examples 3 to 4]
The same procedure as in Comparative Example 1 was performed except that a pitch control agent was added to the measurement sample.

  The results of Examples 5 to 8 and Comparative Examples 1 to 4 are shown in Table 2. In addition, about the cut rate (%) in a table | surface, it calculated | required from the increase / decrease in the amount of extract in Comparative Examples 1-4 by calculating | requiring from the increase / decrease in the wet mass weight calculated using the said Sauerbrey formula from (DELTA) f about Examples 5-8. Calculated.

  As shown in Table 2, when Δf of Examples 5 and 6 and Examples 7 and 8 were compared, it decreased before and after F / T. This indicates that the so-called adhesive foreign matter has been removed reliably by F / T. On the other hand, when the extract amounts of Comparative Examples 1 and 2 and Comparative Examples 3 and 4 are compared, the extract amount decreases after F / T, but the difference is small. This is presumably because the amount of toluene extracted in addition to the sticky foreign matter falls within the measurement range in the method of the comparative example, and the amount of sticky foreign matter reduced is influenced by the amount of other extracts. Therefore, the difference in the cut rate between Examples 5 and 6 and Examples 7 and 8 in which the chemical effect was confirmed is about 20%, whereas the difference between Comparative Examples 1 and 2 and Comparative Examples 3 and 4 Is only about 6%. Moreover, when calculating D / F which shows the viscoelasticity of a deposit | attachment, although there is almost no difference in Example 5 and 6, Example 8 is reducing compared with Example 7 largely. This is considered to have shown that the fine adhesion foreign material was removed efficiently by adding the chemical | medical agent.

[Example 9]
This was carried out in the same manner as in Example 5 except that the actual machine recycled pulp finished raw material was used as the measurement sample.
[Example 10]
The measurement was performed in the same manner as in Example 5 except that a sample obtained by treating an actual recycled pulp finished raw material with a cavitation jet apparatus disclosed in Japanese Patent Application No. 2005-101845 was used.

[Comparative Example 5]
The same operation as in Example 9 was performed except that a quartz crystal whose surface was coated with stainless steel was used.

[Comparative Example 6]
The same operation as in Example 10 was performed except that a quartz crystal whose surface was coated with stainless steel was used.

  Table 3 shows the results of Examples 9 to 10 and Comparative Examples 5 to 6.

  In Example 10 in which the cavitation jet treatment was performed, Δf was significantly reduced as compared with Example 9 in which the treatment was not performed. That is, it was considered that the degree of deposition on the quartz crystal unit was reduced by hydrophilizing the pitch surface by hydroxy radicals generated by cavitation. On the other hand, in Comparative Examples 5 and 6, the difference did not appear clearly. Thus, it was confirmed that the reliability of measurement was improved by coating the surface of the crystal resonator with an appropriate substance.

[Example 11]
The measurement was carried out for more than 10 hours using the on-line device shown in FIG. 2, and the filtrate continuously filtered using a filtrate collection device (trade name: REX-100S-ST) manufactured by Koei Industry Co., Ltd. The same operation as in Example 1 was carried out except that it was used. The results are shown in FIG. With the passage of time, Δf tends to decrease, and it can be seen that foreign matter is deposited on the surface of the crystal unit. The deposition rate was high at the beginning of the measurement and then slowed down. In addition, Δf varies after 8 hours from the start of measurement. This is due to the operation of washing with water and re-measurement. In this way, it was confirmed that online measurement was possible and the degree of deposition could be confirmed.

It is an on-line measurement flow of the present invention incorporating an on-line watering device. It is an online measurement flow of the present invention by incorporating an online water squeezing device and using a 4-channel intermolecular interaction analyzer. It is a graph which shows the measured value of (DELTA) f and (DELTA) D by this invention. It is a graph which shows the measured value of (DELTA) f and (DELTA) D which measured continuously for 8 hours by this invention.

Claims (9)

A method for measuring the degree of foreign matter deposition using a microbalance having a quartz oscillator in a pulp and paper manufacturing process. The measuring method according to claim 1, wherein the pulp and paper manufacturing process is a process of treating process water having a long fiber content of 50% by weight or less based on the total solid content. 3. The measuring method according to claim 1, wherein the foreign matter for measuring the degree of deposition is a hydrophobic organic substance, and the surface of the crystal unit is coated with a hydrophobic substance. The measuring method according to claim 1, wherein the foreign matter is an adhesive foreign matter. The measuring method according to claim 1, wherein the foreign matter is a pitch. The measuring method according to claim 1, wherein the foreign matter is a scale. The microbalance having a crystal resonator can measure a change in frequency (Δf) and a dissipation value (ΔD) caused by foreign matter adhering to the surface of the crystal resonator. Measuring method. The measurement method according to claim 1, wherein the measurement is performed online. The measurement method according to any one of claims 1 to 8, wherein the filtrate is collected using an online water squeezing device and measured online using the filtrate.

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