JP3106266B2 - Pulsating sheet making method and device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for forming a sheet by filtering a pulp slurry for measuring the drainage of the pulp slurry, for measuring the yield of fillers and fine fibers, or for evaluating the physical properties of paper. Related to the device.

[0002]

2. Description of the Related Art In the paper manufacturing process, the measurement of drainage and retention of pulp slurry has become increasingly important due to advances in papermaking machines, retention aids, and diversification of papermaking raw materials. It is also important to evaluate in advance the physical properties of the sheet made from these raw materials. These measurements are made by laboratory filtration of the pulp slurry or by making sheets. However, there is not much improvement in measuring devices such as drainage and one-pass retention, which are used as a measure of the running property of a papermaking machine. The measured values of drainage and retention measured with conventional measuring equipment often differ from the tendency of drainage and retention in the papermaking process in the actual machine, so it is not reliable as a test method and reflects the actual situation of the actual machine The development of such measurement methods and devices has been awaited. In addition, when making a handmade sheet in a laboratory to examine the physical properties of paper, it is made by a pulp test handmade paper preparation method specified in JIS,
The paper layer structure of the sheet created by this method was far from the sheet of the actual machine.

That is, in a paper machine represented by a fourdrinier type, a pulp slurry containing fine substances such as fine fibers and fillers, and internal additives such as a paper-strength enhancer and a sizing agent is converted into a high-speed wire screen ( A predetermined amount of the slurry is flowed from a head box as a slurry having a concentration of 0.1 to 1% on a wire. The water in the slurry is dehydrated as white water together with fillers and fine fibers via a wire. The wire runs while being supported by a table roll or hydrofoil (hereinafter, referred to as a foil), but the slurry on the wire is dehydrated by the head difference from the wire mesh,
Dewatered by decompression by table rolls and foils. However, table rolls and foils act not only as a depressurizer but also as a pressurizer for the slurry on the wire. That is, when the slurry on the wire gets close to the table roll on the wire, semi-dehydrated white water under the wire is sandwiched between the roll and the wire and pressed. That is, the dehydration is temporarily stopped, and instead, white water flows back into the slurry through the wire, and the slurry is pressurized and lifted. In other words, one table roll exerts pressurizing and depressurizing effects on the slurry on the wire, and the effect of dehydration depends on the diameter of the table roll, running speed, and slurry concentration. In the initial stage of dehydration, fine substances are easily removed from the wire because the slurry concentration on the wire is low and there is almost no mat formation. When dehydration proceeds to some extent, a mat is formed on the wire, and the formed mat is broken in the paper layer by a table roll or foil, and part of the mat is re-dispersed in the slurry, and at the same time, creates a passage for water. In the next vacuum dehydration process, the water in the slurry is dehydrated along with the fine fibers and filler in the slurry through the water passage created by the pressurizing action, and becomes so-called white water. When formation of the mat proceeds to some extent, fine fibers and fillers are efficiently adsorbed on the mat mainly composed of long fibers according to the properties of the slurry. Therefore, the filler distribution in the sheet of the actual machine is small on the wire side and large on the felt side. As described above, in an actual paper machine, the pressurizing action and the depressurizing action repeatedly act on the pulp slurry, and the drainage and yield of the slurry behave in a complicated manner according to wet end chemistry.

Conventionally, the drainage of generally used slurries is evaluated by a value obtained by experimenting and measuring in a static state, as represented by a Canadian standard type freeness tester. Although ordinary, improvements were made to approximate the drainage of the actual machine, and as a device to make the sheet, the slurry on the wire was dewatered while stirring with a powerful rotating stirring blade to create a sheet. A dynamic drainage tester and a dynamic sheet making device were developed. FIG. 1 shows a dynamic sheet creating apparatus as an example of such an apparatus.
Stirrer blade c whose upper part of cylindrical container a is rotated by stirrer b
And a jar e having a baffle plate d on the inner wall surface, and a lower portion thereof is formed as a filtrate collection bottle h having an inlet f for pressurized air and an outlet g for air. A wire i is provided between the collection bins h. When measuring drainage, pressurized air is blown from the inlet f to pressurize the pulp slurry so as not to leak from the wire i, and then a predetermined amount of pulp slurry is injected into the jar e. The pulp slurry is disturbed by air bubbles, and the stirring blade c is rotated at the same time, and the pulp slurry is filtered while alternately pressurizing and depressurizing the filtrate collecting bottle h by switching a valve. Then, the drainage is evaluated based on the filtration time, and the SS content of the filtrate collected in the collection bin h is measured to evaluate the retention. However, the values measured by this apparatus vary widely and are insufficient for evaluating the yield of drainage and fine substances of an actual machine, and a practical sheet cannot be produced.

[0005] In addition, a hand-made sheet is prepared according to the JIS-specified method in which the slurry concentration is 0.01 to 0.03%.
Very thin and the head difference is 11 for standard handmade sheets
There is also 5cm, at least 80cm at all times, which is significantly different from the actual dewatering conditions. Dehydration is also static, and the finished sheet naturally has a different paper layer structure from the actual machine sheet. For this reason, there has been an increasing demand for a sheet made by an actual machine simulation type device in which a hand-made sheet also has a paper layer structure reflecting the actual machine, but there has been no simple experimental device corresponding to this.

[0006]

As described above, with the speeding up of paper machines and the diversification of raw materials, fillers and internal chemicals, the evaluation of drainage of pulp slurries, and one-pass retention and retention aids are increasing. It has become an important issue, and there is a high demand for a method of making a hand-made sheet whose paper layer structure, such as the distribution of fillers and the distribution of fine substances, is close to that of an actual machine. In addition, as described above, the fourdrinier machine is pulsatively repeated pressurization and depressurization using a table roll or a foil, and the drainage performance of the actual machine is a reliable evaluation even with an improved dynamic drainage tester. Could not. Furthermore, with the current equipment for evaluating retention, drainage, and sheets, it is difficult to create a sheet for evaluating sheet properties, etc., and the measurement of drainage and the creation of a sheet for evaluating physical properties of paper are separate. At present, the conditions for forming the sheet are very different from those of the actual machine, so that the actual conditions of the sheet are far from those reflecting the sheet layer structure. In addition to measuring drainage and collecting filtrate, if a sheet simulating an actual machine for evaluating sheet physical properties can be created at the laboratory level at the same time, the drainage of slurry when various chemicals and fillers are added In addition to evaluation of sheet and retention, sheet properties such as formation properties and strength properties, as well as filler distribution, can be measured with something close to the actual machine sheet, making it convenient for research and development of wet end chemistry in future papermaking. is there.

An object of the present invention is to propose a sheet forming method and apparatus which can perform evaluations close to those of an actual machine, solve the above-mentioned problems and simultaneously satisfy the above-mentioned needs.

[0008]

According to the present invention, in order to attain the above object, a stirred pulp slurry is filtered through a wire provided in a jar, and the filtrate is provided at an intermittent pressure higher than the atmospheric pressure. In a method of collecting fibers in a collection bin where pressure and vacuum pressure act alternately, and forming a mat of fibers in a pulp slurry on the wire, a flow path of a filtrate from below the wire to the collection bin is airtightly sealed. The pulp slurry was configured so as to be filled with a liquid before starting filtration.

In this method, a stirring tank for stirring a pulp slurry is provided above a jar provided with a wire, and a filtrate flowing down through the wire is collected under an intermittent pressurized and reduced pressure below the jar. In a device for receiving mats of fibers in a pulp slurry on a wire received in a bottle, the lower part of the wire of the jar is formed into a funnel, and the inside of the funnel and the inside of the collection bottle are hermetically sealed with a conduit. This is conveniently implemented by coupling to

[0010]

The pulp slurry to be tested is stirred in a place different from the jar and then supplied into the jar. Therefore, the pulp slurry in the jar is filtered by the wire in the jar without being subjected to centrifugal force by a stirrer,
During this filtration, a pressure higher than the atmospheric pressure and a vacuum pressure are alternately applied to the collection bottle, and the pulsation is transmitted to the pulp slurry via a wire, and the pulp slurry is pulsatively pressurized and dewatered, and the filtrate is discharged. Collected in a collection bin. in this case,
The fibers and fine substances in the pulp slurry are captured by the wire and deposited in a mat form, but the passage of the filtrate to the collection bin is connected by an airtight thin conduit, which is filled with liquid in advance. Since the pressurization and decompression acting on the collection bin are transmitted to the entire surface of the wire through a conduit filled with water during the progress of the mat deposition, dehydration and mat preparation are performed in a pulsating state similar to the actual machine. Can be done. Therefore,
For example, from the measured value of the filtration time of the filtrate, the drainage of the pulp slurry in an actual machine can be approximately known.
However, the conventional dynamic drainage tester described above measures while stirring the pulp slurry with a stirrer, so that the pulp slurry receives centrifugal force due to rotation, and is far from the behavior of the actual machine. Although pulsation is performed by air pressure as in the present invention, pressure is not transmitted to the wire portion via the liquid, but the variation of air pressure is directly transmitted to the wire portion, so that pulsation can be controlled. It was difficult and it was not possible to perform a simulation assuming a real machine.

Further, in the apparatus of the present invention, since the liquid is previously put in contact with the wire located above the funnel, when the pulp slurry to be tested is poured into the jar, the fibers in the pulp slurry are removed from the wire by the wire. And the occurrence of clogging is reduced. In addition, since the lower part of the jar is formed into a funnel and the inside of the funnel and the inside of the collection bottle are connected by a thin conduit, the pre-filled liquid can be minimized and the collection bottle can be minimized. Can reduce the total amount of filtrate collected at the same time.

[0012]

BRIEF DESCRIPTION OF THE DRAWINGS FIG.
In FIG. 2, reference numeral 1 denotes a cylindrical jar having an open upper end in which a wire mesh wire 2 is detachably provided, and a stirring tank 3 is provided above the inside of the jar 1. Inside the stirring tank 3, a baffle plate 4 fixed to an inner wall thereof and a rotating stirring blade 6 of a stirrer 5 are provided, and pulp slurry is injected from an opening above the stirring tank 3. At the bottom of the stirring tank 3,
An inflow pipe 8 having a cock 7 is provided, and the pulp slurry flows down into the jar 1 when the cock 7 is opened. A funnel 9 is provided below the wire 2 of the jar 1.
A conduit 12 with a cock 11 is provided on the way from the lower part to the lower airtight collection bin 10. The conduit 1
A rubber plug 26 or the like is provided around the periphery of the tube 2 so as to be air-tightly attached. The inside of the funnel 9 and the inside of the conduit 12 are filled with a liquid such as water prior to measurement of drainage and preparation of a mat.

The bottom of the collecting bottle 10 is formed in a funnel shape for taking out the collected filtrate.
3 was provided. The collection bin 10
Is connected to a pulsating device 16 via a connecting pipe 15, and the inside of the collection bin 10 is controlled to a pressure higher than the atmospheric pressure and a vacuum pressure.
The pulsation device 16 has a configuration that is alternately connected to a pressurizing device 19 of a cylinder or a compressor and a vacuum pump 20 via a three-way solenoid valve 18 controlled by an on / off timer 17. A pressure sensor 21 and a recorder 22 for detecting the pressure are provided on the connection pipe 15. 23 is an adjusting valve for adjusting the vacuum pressure of the vacuum pump 20, and 24 is an adjusting valve for adjusting the pressure from the pressurizing device 19. In the case where the pressure in the collection bin 10 is pulsated by the atmospheric pressure and an appropriate pressurization, the vacuum pump 20 does not need to be provided, and the connection port of the regulating valve 23 only needs to be opened to the atmosphere. .

An umbrella-shaped distribution plate 25 having a large number of small holes is provided at the outlet of the inflow pipe 8 of the stirring tank 3 so that the pulp slurry flowing out of the inflow pipe 8 does not directly collide with the wire 2. In addition, they were dispersed on the wire 2 as uniformly as possible.

The pulp slurry placed in the stirring tank 3 is stirred by a suitable shearing force by the stirring blade 6, and at this time, fillers, internal additives, retention aids and the like are introduced. The pulp slurry sheared by the stirring is prepared as a sample for measuring drainage and yield, and the cock 7 of the inflow pipe 8 is opened to flow down into the jar 1 at a stretch. The stirring tank 3 is an important device for experiments requiring high precision. However, in a general experiment, stirring of the pulp slurry is performed by stirring a perforated plate specified in JIS P 8209 instead of the stirring tank 3. The mixture may be stirred by a stirrer according to the machine, or may be charged into the jar 1 and tested after stirring by a household mixer or the like.

The capacity of the funnel 9 below the jar 1 and the filling of the funnel 9 with a liquid such as water are important conditions for conducting experiments such as drainage. That is, if the funnel 9 is not filled with the liquid, the wire screen 2 is clogged by pulp or the like when dewatered, so that the measured values of drainage and yield become large, and highly reliable data is obtained. I can't get it. However, it is not necessary to fill the funnel 9 with 100% liquid, and when the funnel 9 is filled with 90% or more of water, the variation in data is reduced, and highly reliable data can be obtained. The capacity of the funnel 9 is not limited, but a smaller one is preferable for measuring the SS content later.

The filtrate from the pulp slurry is collected in a collection bin 10
The interior of the conduit 12 below the funnel 9 leading to the inside is also filled with liquid, but the thickness and length of the conduit 12 are not particularly limited.
Preferably, the inner diameter is about 3 to 10 mm, and the length is an important factor that determines the height from the liquid level when the pulp slurry is charged into the jar 1 to the inlet of the collection bin (head difference = water column),
The filtration flow rate is determined by this, but is appropriately set according to the dehydration time and the like. The flow rate of the filtrate can be adjusted by adjusting the length of the conduit 12 or by providing an orifice and adjusting its opening. By providing a transparent portion in the middle of the conduit 12 and measuring the transparency of the filtrate passing therethrough, it is possible to measure the change in SS of the filtrate over time.

The collection bottle 10 may be large enough to contain the filtrate, but if the volume is too large, the air inside will serve as a cushioning material and the response of the controlled air pressure from the pulsation device 16 will be poor. It is not preferable. The discharge pipe 1
Numeral 4 is an optional one. When there is no rubber, the filtrate may be transferred by removing the rubber stopper 26. By providing cocks in each of the branched conduits and connecting a collection bottle to these tips, the filtrate can be collected over time.

The three-way solenoid valve 18 has an on / off timer 1
7, the on-time and off-time are arbitrarily controlled. In this embodiment, the vacuum pump 20 is connected to the connection pipe 15 when off, and the pressurizing device 19 such as a pressure pump is connected to the connection pipe 15 when on. I did it. The pressure of the pressurizing device 19 is set by turning on the on / off timer 17, closing the cock 11 of the conduit 12 of the funnel 9 to close the collecting bin 10, and collecting the pressurizing device 19 via the three-way solenoid valve 18. Bin 1
Connect to 0. Then, while watching the pressure sensor 21, the control valve 24 of the pressurizing device 19 is adjusted to a desired pressure. After this pressure adjustment, the ON time of the ON / OFF timer 17 is set. Similarly, connect the vacuum pump 20 to the three-way solenoid valve 1
8 is turned off, the adjustment valve 23 is adjusted while watching the pressure sensor 21, and after adjusting to a desired vacuum pressure, the off time is set.

The configuration of the apparatus according to the present invention has been described above. The method for producing drainage, yield, and sheets using the apparatus will be described below. Although the size of the device does not limit the present invention, for the sake of explanation, the diameter of the jar 1 is set to 100 mm.
φ, the diameter of the stirring tank 3 is 50 mmφ.

The apparatus of the present invention can cover most of the slurry concentration used in an actual machine. That is, the slurry concentration of the actual machine is usually 0.1 to 1.0%, and generally about 0.3%. Therefore, the slurry concentration simulated on the actual machine is 0.3% (this is the same as the pulp slurry concentration measured with a Canadian standard type freeness tester)
A sheet having a dry basis weight of 95.5 g / m ² (corresponding to a pulp slurry capacity of 250 cc) when the yield is 100% will be described.

(1) Setting of Conditions One feature of the present invention is that a dewatering method close to an actual machine can be experimentally performed. That is, it is possible to simulate the pressurization and depressurization of the slurry, which is alternately and repeatedly pulsated by the table roll and the foil, in a laboratory.
When conducting experiments on various actual machines, the time until the pulp slurry is dehydrated and the number of pulsations vary depending on the papermaking speed, wire length, thickness and number of table rolls, and the like. To do so, set the simulation conditions,
A pulsation condition that meets the condition is set. The pulsation conditions are set under the conditions assumed for the actual machine. For example, if the length of the wire part of the paper machine is 30 m and the paper making speed is 600 m / min,
Dehydrate in 3 seconds. If the total number of table rolls and foils at that time is 20, the number of pressure reduction / pressure pulsations in 20 seconds will be 20
The pulsation device 16 is set so as to be turned. The setting method is as described above. Incidentally, the ratio between the pressurizing time and the depressurizing time can be set to, for example, 1: 2. In this case,
The pressurization time is set to 0.05 seconds and the decompression time is set to 0.1 seconds.

(2) Setting of Pressure in Collection Bin After the setting of the pulsation device 16 is completed, the pulsation device 16 is moved, and the pressure in the collection bin 10 is checked by the pressure sensor 21. Since the pressure changes pulsatingly, if the response value of the pressure sensor 21 is recorded in the recorder 22, the subsequent analysis becomes easy. Next, the dewatering time at the set value of the pulsating device 16 was measured using the same amount of fresh water as the slurry (about 250 cc = water column 32 mm), and it was confirmed that the dewatering time was the set time (for example, about 3 seconds). I do. Also at this time, the funnel 9 and the conduit 1
In No. 2, the dewatering time is measured in a state in which fresh water is filled in advance.
If dehydration cannot be performed within the set time, the conditions of pressurization and depressurization are readjusted so that dehydration can be performed within the set time. When dewatering the actual pulp slurry, the dewatering time may be longer than the allowable limit depending on the mixing conditions of the pulp slurry.In such a case, re-adjust the dewatering conditions depending on the purpose of the experiment, or in some cases, open the orifice. And conduit 1
2 by adjusting the length. If the length of the conduit 12 is increased, dehydration can be performed in a short time, and if shortened, a long time is required. When the pulsation device is set, the funnel 9 and the conduit 12 are filled with fresh water. The funnel 9 may be filled with fresh water to 90% or more of its volume as described above. However, in order to reduce experimental errors and to make the handling of the filtrate uniform, the funnel 9 is filled with almost 100% clear water. Better.

(3) Stirring of the Slurry The absolute dry weight of the slurry having a concentration of 0.3% of 95.5 g / m ² requires 31.8 kg as the weight of the slurry, which is equivalent to 31.8 mm in terms of the water column height (the weighing is 31.8 mm). As the height decreases, the height of the water column decreases proportionally.)
cc. When this slurry is placed in a stirring tank 3 of 50 mmφ, the height of the water column is quadrupled to 127.2 mm, which is a sufficient height for stirring. Then, the mixture is stirred by the stirrer 3 at the rotation speed and rotation time set based on the experimental plan.

(4) Supply of Pulp Slurry to Jar 1 After stirring under predetermined conditions, the cock 7 of the inflow pipe 8 is opened, and the slurry flows down into the jar 1 at a stretch. When the slurry directly collides with the wire 2, the fibers in the slurry stick into the mesh of the wire 2 and cause clogging. This can be prevented by providing the distribution plate 25. The material and weaving method of the wire 2 can be freely selected according to the purpose of the experiment.

(5) Measurement of drainage time After the slurry is allowed to flow down from the stirring tank 3 into the jar 1 at once, the cock 13 of the conduit 12 is opened immediately. Thereby, the water in the slurry is filtered by the wire 2 and dewatered. The end of the dehydration is determined based on the condition of the mat formed on the wire 2 running out of water. The time from the moment of dehydration to running out of water is measured with a stopwatch, and the drainage time is determined.

(6) Collection of mat After the dehydration, the on / off timer 17 is turned off, the three-way solenoid valve 18 is turned off, the cock 11 is closed, and the collection bin 1
Raise the degree of vacuum in 0, and when it reaches a certain degree of vacuum, cook 1
1 is opened at a stretch, and the moisture of the mat formed on the wire 2 is sufficiently sucked. This operation is an operation on the assumption of a vacuum box provided in an actual machine, and also leads to a reduction in experimental errors of the mat. Next, the mat is taken out of the jar 1 together with the wire 2, and the mass of the mat is measured. The mass of the mat is an index of dehydration. Thereafter, the water content of the mat is removed with a filter paper and a roller, and the mat is peeled off from the wire 2 and processed according to the JIS hand sheet manufacturing method to obtain a hand sheet. The sheet after drying and humidity control is used for evaluation of sheet properties such as strength and formation measurement, ash content measurement, and measurement of filler distribution in the sheet by electron beam analysis.

(7) Collection of Filtrate and Measurement of Yield The filtrate collected in the collection bin 10 is supplied to the cock 1 of the discharge pipe 14.
Open 3 and transfer to another bottle to use as a sample for filtrate analysis such as SS measurement. The yield is calculated from the SS measurement.

In the above operation, by changing the setting of the pulsating device 16 or changing the length of the conduit 12,
Detailed experiments can be performed according to the running speed of the actual machine and the number of pulsations. Further, since the pulp slurry is stirred in a place different from the jar 1, the pulp slurry can be sufficiently stirred, and the stirring tank 3 and the wire 2 are separated from each other. Clogging can also be prevented. Next, a comparative test was performed between the sheet according to the present invention and a sheet prepared using a dynamic drainage tester (referred to as DDJ) according to FIG. In the case of the present invention, the apparatus shown in FIG. 2 was used. In both the case of the present invention and the case of DDJ, the jar and the collection bottle are the same size and both are equipped with a stirrer. However, in the case of the present invention, the stirrer and the stirring tank are separate from the jar, and a funnel and a conduit filled with fresh water are provided below the wire. The conditions of the actual machine assumed in this comparative test were that the speed of the papermaking was 500 m / min and the length of the wire part was 3
0m, 30 table rolls at 100cm intervals, dehydration time 3.
6 seconds (when fresh water is dehydrated), pulse rate (pressurizing time + depressurizing time) = 0.12 sec / 1 cycle, pulp slurry concentration
The absolute dry weight when the yield is 0.3% and the yield is 100% is 95.5 g / m ² . In the measurement data, the measured value according to the present invention was used as
Expressed as I.

Test Example 1 Using pulp blended with 150-mesh long fibers obtained by beating virgin eucalyptus pulp (LBKP) 10,000 times with a PF1 mill and 150-mesh pass fine cardboard waste paper. The effect of stirring was studied. The pulsation conditions were 790 mmHg for pressurization and 760 mmHg for decompression. Test example 3
What was described in was used. The pulp slurry was stirred at 1000 rpm for 2 minutes in both the present invention and DDJ, and then used as a test sample for filtration. The test was performed four times while changing the amount of the fine fibers. Table 1 shows the results.
It is as follows.

[0031]

[Table 1]

As can be seen, in the case of the DDJ in which the stirring was performed in the jar, the R (variation) of the sheet thickness was very large.
Is getting bigger. The reason for this is that the long fibers of the pulp gather around the center of the cylinder of the jar due to agitation and become thicker, and the fine fibers and fillers with high density gather around the periphery and become thinner. It cannot be used as a sheet for measuring sheet properties.
In contrast, the sheet according to the present invention has good uniformity and can be used for measurement. In addition, the DDJ sheet had a large variation in whiteness, the central part of the stirring blade was white and the peripheral part was gray, indicating that the fine fibers were unevenly distributed.
Although not shown in the data, the whiteness of the DDJ sheet has a large difference between the front and back sides, and the backside (wire side) whiteness is lower. On the other hand, in the sheet according to the present invention, the variation in whiteness is small, the difference between front and back is small, and the fine fibers are uniformly distributed. Therefore, the apparatus of the present invention applies a sufficient shearing force (stirring) to the pulp slurry, and then dewaters while pulsating, so that a uniform sheet can be easily prepared.

Test Example 2 A feature of the present invention is that the flow path of the filtrate from the lower part of the wire to the collection bottle is air-tightly constituted by a funnel and a conduit, and the liquid is filled in advance before starting the filtration of the pulp slurry. However, the effect of this configuration on the results was compared and examined depending on whether the funnel was previously filled with water. The pulp formulation was the same as in Test Example 1. In the apparatus of the present invention, a flexible hose having an inner diameter of 10 mm
m) was used to fill the funnel and conduit with water (these volumes were approximately 200 cc). The conditions of pressurization and decompression are the same as in Test Example 1. In the test performed without filling the funnel with water, there was a space of about 3 liters below the wire including the capacity of the collection bottle, but the test was performed while pulsating other portions as in the present invention. Table 2 shows the test results.

[0034]

[Table 2]

Conditions where the funnel and conduit are not filled with water (DD
In the experiment of dehydrating while pulsating in the same manner as in the present invention in J), when the pulp slurry was poured into the jar with the beaker after closing the cock 11, the fibers in the pulp slurry were clearly stuck on the wire. At the same time, a portion of the pulp slurry leaked out of the wire immediately after the injection. When the cock 11 is opened next time, bubbles are generated in the pulp slurry through the wire. Therefore, it is difficult to control the dewatering time even if the internal pressure in the collection bin is reduced and dewatering is performed. I couldn't make a perfect sheet. However, as in the present invention, the funnel 9 and the thin conduit 12 are provided below the wire, and the liquid is previously filled in the funnel 9, so that a uniform sheet can be produced.

Test Example 3 The influence of the presence or absence of the distribution plate 25 was tested with the configuration shown in FIG.
In the case of FIG. 2, the distribution plate 25 is an inverted funnel type having an inner diameter of 80 mm and a height of 10 mm, and is formed by uniformly dispersing about 40 holes having a diameter of 5 mm. The pulp slurry, stirring conditions, and the like are the same as those in Test Example 1. Table 3 shows the test results.

[0037]

[Table 3]

Without the distribution plate 25, when the pulp slurry flows down from the stirring tank 3 into the jar 1, the pulp sticks to the wire 2 and causes clogging (this phenomenon is noticeable when the funnel is not filled with water). Happens). The part where clogging has occurred (the part directly under the cock 7) has a thin mat,
When the mat was peeled off from the wire 2, a part of the mat remained on the wire 2, disturbing the formation of the mat and making a uniform sheet impossible. When the distribution plate 25 was provided, the pulp slurry flowing down from the stirring tank 3 was smoothly spread on the wire 2 on average, and a good sheet without clogging was obtained.

Test Example 4 The influence of the length of the conduit 12 was tested with the configuration shown in FIG. The pulp slurry of Test Example 1 having no fine fiber was used.
The pulsation conditions are as follows: pressurization is 790 mmHg for 0.1 second, decompression is 760 mmHg
For 0.05 seconds. Other conditions are the same as in the case of Test Example 1. Table 4 shows the results.

[0040]

[Table 4]

The length of the conduit shown in Table 4 means the pulp slurry 25
It represents the liquid level when 0 cc is injected into the jar 1 and the height to the tip of the conduit 12 reaching the collection bin 10. Also, the differential pressure is a difference between the atmospheric pressure and the pressure inside the collection bin 10,
The correlation between differential pressure and dehydration time is high. The dehydration time can be controlled by expanding and contracting the length of the conduit 12. That is, when the conduit 12 is shortened, the differential pressure decreases and the dehydration time increases, and when the conduit is shortened, the differential pressure increases and the dehydration time decreases. In addition, the influence of the amount of fresh water when the conduit is expanded and contracted is that if the diameter of the conduit 12 is 10 mmφ, extending the length by 1 cm is approximately 0.8 cc, and even 10 cm in length is equivalent to less than 8 cc of water,
Subtle dehydration time can be controlled by increasing or decreasing the amount of fresh water.

Test Example 5 Using a retention aid by the apparatus of the present invention, the difference in drainage (dehydration time) depending on the presence or absence of pulsation was examined. The composition of the pulp slurry is the same as in Test Example 1, but
Calcium carbonate was internally added as a filler at 100% of pulp. Other conditions were set in the same manner as in Test Example 1. The condition of pulsation is 0.04 seconds at pressurization of 780 mmHg and o.03 at decompression of 680 mmHg.
Seconds. The retention aid uses a cationic polymer, and the amount added is 0.025%, 0.05%, 0.1% of pulp.
It changed to and tested. Other conditions were set in the same manner as in Test Example 1. Table 5 shows the results.

[0043]

[Table 5]

When there was pulsation, the dehydration time was shortened as the retention aid was added, and the effect was recognized. However, when there was no pulsation, no difference was observed in the dehydration time. Therefore, the pulsation allows the dehydration time (filtration) to be measured more accurately. In addition, the ash content of the sheet indicates that when no retention aid is added, the yield without pulsation is lower, but when the retention aid is internally added, the yield with pulsation is worse.
This suggests that the process of paper layer formation differs depending on the presence or absence of pulsation.

Test Example 6 A test was conducted under the same conditions as in Test Example 5 except that titanium dioxide was internally added to the pulp in an amount of 20% instead of the calcium carbonate in Test Example 5. As a result, drainage and yield showed the same tendency as in Example 5. When the distribution of the filler in the Z direction of the obtained sheet was analyzed by an X-ray microanalyzer, as shown in FIG. 3, the distribution of the filler of the sheet filtered while applying pulsation showed a distribution on the wire side. And the surface on the opposite side show approximately the same amount of distribution, but the sheet made by filtration without pulsation has a larger filler distribution on the wire side surface. Filler distribution in Fourdrinier paper machines generally tends to be smaller on the wire side than on the opposite side, but increases on the wire side in the hand-made sheet by the JIS method. . According to this test, it was confirmed that a sheet having a filler distribution closer to that of an actual machine can be experimentally produced by applying pulsation.

In the above Test Examples 1 to 6, the tests were conducted taking into account the preparation of the hand-made sheet. However, if only the drainage and the yield of the pulp slurry were evaluated, the test examples were followed. Can be tested by method. That is, since Test Examples 1 to 6 are intended for sheet preparation, the pulp slurry was charged at 250 cc.
000-2000cc pulp slurry can be charged,
More accurate evaluation experiments are possible.

[0047]

As described above, according to the method of the present invention, the pulp slurry is intermittently collected in a collecting bin in which a pressure higher than the atmospheric pressure and a vacuum pressure alternately act to form a pulp sheet on a wire screen. In this method, the flow path of the filtrate from below the wire screen to the collection bin is air-tightly configured and filled with the liquid before starting the filtration of the pulp slurry. A sheet close to the sheet created by an actual paper machine transmitted to an actual paper machine can be experimentally created, and in this creation, an evaluation close to the drainage of the actual machine can be performed. It can be conveniently implemented, and has effects such as being able to conduct experiments according to various conditions of the actual machine.

[Brief description of the drawings]

FIG. 1 is an explanatory view of a conventional dynamic drainage tester (DDJ)

FIG. 2 is an explanatory view of the apparatus of the present invention.

FIG. 3 is an analysis diagram of a sheet prepared according to the present invention using an X-ray microanalyzer.

[Explanation of symbols]

1 jar 2 wire screen 3
Stirrer tank 5 Stirrer 9 Funnel 10
Collection bin 11 cock 12 conduit 16
Pulsating device 25 Distribution plate

Claims (5)

(57) [Claims] 1. The pulp slurry is filtered through a wire screen provided in a jar, and the filtrate is intermittently collected in a collecting bin provided below and intermittently acting at a pressure higher than the atmospheric pressure and a vacuum pressure alternately. In a method of forming a mat on the wire screen from the fibers in the pulp slurry to produce a hand-made sheet, a flow path of a filtrate from below the wire screen to a collection bin is airtightly connected thereto. A method for producing a pulsating sheet, wherein a liquid is filled in advance before starting filtration of a pulp slurry. 2. The pulp slurry is filtered by a wire screen provided in a jar, and the filtrate is collected in a collecting bin provided below and intermittently interchanging a pressure higher than the atmospheric pressure and a vacuum pressure intermittently. In an apparatus for forming a hand-made sheet by forming a mat on the wire screen from the fibers in the pulp slurry, the lower part of the jar under the wire screen is formed into a funnel, and the inside of the funnel and the collection bin are formed. And a pulsating sheet making device, wherein the device and the device are airtightly connected by a thin conduit. 3. The pulsating sheet producing apparatus according to claim 2, wherein the length of the conduit is variable. 4. A stirring tank for stirring the pulp slurry is provided above a jar provided with a wire screen, the stirring tank includes a rotating blade of a stirrer and a baffle plate, and a cock is provided at a bottom of the stirring tank. The pulsating sheet producing apparatus according to claim 2, further comprising a discharge pipe. 5. The pulsating sheet forming apparatus according to claim 2, wherein a perforated umbrella-shaped distribution plate is provided above the wire screen.