JPH09243622A - Method and apparatus for measuring content of highly water absorbable resin in absorbing material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To efficiently measure the content of AGM in the absorbing material of a paper diaper with high accuracy. SOLUTION: Slits are formed to tissue along two opposed sides in the longitudinal direction of a paper diaper and, further, an absorbing material layer is taken up along with the back sheet applied thereto to form a cylindrical sample having slits at both ends thereof (S1). This sample is vertically immersed in hydrochloric acid in a reaction tank and bubbles are jetted from the apertures of the bottom part of the reaction tank to be passed through the absorbing material layer from the slits of the rear surface of the samaple toward the slits of the upper surface thereof (S23). By this constitution, the preparing labor of the sample becomes simple and the reaction of AGM can be rapidly performed without stirring hydrochloric acid. Subsequently, hydrogene ions excessive in hydrochloric acid wherein AGM is reacted are determined (S32) to calculate the consumed amt. of hydrogen ions and, on the basis of this result, the amt. of AGM is calculated (S33). By this reverse titration, AGM can be determined with high accuracy even when the amt. of AGM is small.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for measuring the content of superabsorbent resin in an absorbent body comprising a superabsorbent resin and its carrier.

[0002]

2. Description of the Related Art Highly water-absorbent resins generally have a water absorption capacity of several hundred to one thousand times their weight, and are used in many fields such as sanitary materials including paper diapers. FIG.
An external view (a) showing the structure of a disposable diaper using an acrylate-based highly water-absorbent resin (hereinafter referred to as “AGM: Absorbing Gel Material”) as a water-absorbent material, and a cross-sectional view (b) of A1-A2 portion. Is. Air felt 101 in which short fiber pulp is solidified and laminated, and a large number of AGMs carried therein
Absorber layer 1 composed of particles 102 (particle diameter of about 0.5 mm)
03 is a non-woven top sheet 105 that is wrapped in a tissue 104 and is in close contact with the skin and allows urine to pass through, and a back sheet 1 of a leak-proof film that prevents urine from leaking to the outside.
It is sandwiched between 06. The tissue 104 is made of the hot-melt adhesive 107 so that the absorbent layer 103 is not displaced.
Is affixed to the inner surface of the back sheet 106. Further, in order to improve wearability and prevent side leakage, leg gathers 108 having elasticity are provided on both sides of the outer surface of the top sheet 105 along the longitudinal direction of the diaper.

When using this disposable diaper, first, the air felt 101 quickly absorbs the urine that has passed through the top sheet 105, and then the urine held in the voids of the short fiber pulp of the air felt 101 is changed by the AGM particles 102. The absorbed and moist air felt 101 is returned to a dry state. Therefore, the absorption action of the air felt 101 due to the capillarity also works for the next excretion, and continuous use is possible in a plurality of excretion.

Since the water absorption performance of such a disposable diaper is determined by the AGM content of the absorbent layer 103, it is necessary to measure the AGM content of the absorbent layer 103 for one diaper in product development and quality control. Is essential. This measurement has been conventionally performed by the following procedure.

First, as a work for preparing a measurement sample, the absorber layer 103 is taken out from a disposable diaper. To do this,
First, the adhesive portion between the top sheet 105 and the back sheet 106 is cut off with scissors or the like to remove the top sheet 105. Next, in order to remove the absorber layer 103 from the back sheet 106, heat is applied to the portion where the hot-melt adhesive 107 is attached by using a dryer or the like to melt the adhesive. Furthermore, the absorber layer 1
In order to facilitate the reaction between the AGM particles 102 in 03 and the acid solution, the absorber layer 103 is finely cut with scissors.

Then, the cut absorber layer 103 is quantitatively measured. As this quantification method, JP-A-1-26036 is known.
The method described in Japanese Patent No. 1 is known. That is,
During the process in which the AGM particles 102 react with the acid solution, the alkali metal ion (for example, Na ⁺ ) in the alkali metal base (for example, COONa) constituting AGM is replaced with the hydrogen ion H ⁺ in the acid solution, and the COOH group is newly formed. Alkali metal ions are liberated as they are produced. Therefore, the amount of AGM is measured by examining the amount of this alkali metal ion. As an example of a specific method, first, a solution containing a known amount of sodium ions is prepared in advance, the potential difference of the solution is measured using a pH meter equipped with a sodium ion measurement electrode, and a reference value is obtained. The following calibration curve (graph showing the relationship between sodium ion concentration and potential difference) is prepared. Next, after adding ammonia water to the acid solution reacted with AGM to neutralize it, the potential difference is measured using the same pH meter, and the sodium ion concentration is calculated in light of the above calibration curve. And from this sodium ion concentration, A
Calculate the GM amount.

[0007]

However, the conventional measuring method as described above has the following many drawbacks. (1) The absorber layer 103 must be taken out in the state of being wrapped in the tissue 104, and the work of heating the heat-melting adhesive 107 with a dryer to soften it and slowly peeling the backsheet 106 is required. Become. Since this is a work that requires time and skill, it greatly reduces the efficiency of measurement. (2) It is possible to use a stirrer to promote the reaction with the acid solution, but if the short fiber pulp is entangled with the paddle of the stirrer, a sufficient stirring effect cannot be obtained, so that the absorber layer 103 is placed in a container. Before it is put in, it must be cut into small pieces with scissors. At this time, the AGM particles 102 carried on the air felt 101 are scattered. For this reason, some amount of AGM particles 102 will be lost even with the utmost care, and the quantification accuracy will be impaired. (3) Further, since the AGM particles 102 before absorbing water are very hard, the blade of the scissors used for cutting the absorber layer 103 is seriously damaged, and the cost for replacement is high. (4) Even if the absorber layer 103 is cut into small pieces, it is impossible to completely prevent the pulp from being entangled in the paddle. For this reason, it is necessary to perform a cleaning operation for removing the pulp entangled in the paddle every time the stirring operation for one sample is completed, which reduces the measurement efficiency. In addition, this work requires manual labor, making automation of measurement difficult.

(5) When the proportion of AGM in the absorber layer 103 is small, the concentration of alkali salt ions liberated in reaction with the acid solution is also low. Therefore, in the above quantification method, the measurement accuracy is high when the amount of AGM is large, but
If the amount is small, the measurement accuracy will be low. (6) The sodium ion measuring electrode used for the quantification of the above-mentioned conventional technique has a large reproducibility due to a large change with time and temperature. For this reason, practically, it is necessary to recreate the calibration curve each time a sample is quantified, which is extremely time-consuming and labor-intensive. (7) Usually, air felt 10 excluding AGM particles 102
A small amount of sodium ions is also contained in the substance immersed in the acid solution such as 1. Therefore, it is difficult to improve the measurement accuracy of the AGM content by the method of titrating sodium ions.

An object of the present invention is to provide a measuring method and a measuring apparatus for the amount of highly water-absorbent resin in an absorber, which solve these problems.

[0010]

Means for Solving the Problems, and Embodiments of the Invention The present invention, which was made to solve the above problems, provides a method for measuring the content of a superabsorbent resin in an absorber, After contacting the water-absorbent resin with an acid solution containing a known amount of hydrogen ions, surplus hydrogen ions except hydrogen ions consumed by substituting the alkali metal of the alkali metal base constituting the highly water-absorbent resin are removed. It is characterized in that it is quantified and the amount of the super absorbent polymer is calculated based on the measurement result.

Here, a typical absorber is composed of air felt, a highly water-absorbent resin carried on the air felt, and water-absorbent paper (tissue) for wrapping the whole air felt as necessary. Airfelt is usually short fiber pulp.

In the conventional method for quantifying a superabsorbent resin, the concentration of the alkali metal ion liberated in the acid solution was directly obtained, and the content of the superabsorbent resin in the absorber was calculated from this concentration. On the other hand, in the quantification method of the present invention, the amount of hydrogen ions replaced with the alkali metal base of the superabsorbent resin is determined by titrating the amount of excess hydrogen ions in the acid solution that is not consumed in the reaction, and Based on this, the content of the super absorbent polymer in the absorber is calculated. When the content of super absorbent resin is small, the amount of surplus hydrogen ions is large,
Quantification can be performed with high accuracy.

According to this measuring method, hydrogen ions must remain in the acid solution after the superabsorbent resin is reacted. Therefore, it is preferable that the acid solution is prepared in advance so as to contain excess hydrogen ions.

As a method for measuring the amount of surplus hydrogen ions, an alkali metal hydroxide such as sodium hydroxide solution is neutralized as an alkaline solution to an acid solution in which a superabsorbent resin is contacted. Gradually add until
The surplus hydrogen ion amount can be calculated from the amount of the alkaline solution when the acid solution becomes neutral.

Further, in the measuring method according to the present invention,
In order to rapidly react the superabsorbent resin and the acid solution, the absorber is immersed in a reaction tank filled with the acid solution, and gas is ejected from a large number of holes provided in the reaction tank to generate bubbles. It is preferable to employ a treatment method in which the bubbles are allowed to pass through the inside of the absorber to cause the superabsorbent resin in the absorber to react with the acid solution.

In this treatment method, since the bubbles blown out from the holes pass through the voids of the pulp of the air felt, the particles of the superabsorbent resin carried on the air felt are always exposed to the fresh acid solution. Therefore, the reaction proceeds promptly without mechanical stirring.

In the above treatment method, when a water absorbent body wrapped in a predetermined casing is to be measured, an opening for exposing the absorbent body is provided in the casing on two opposite sides, and one of the openings is used for the reaction. It is advisable to immerse the water absorber in the acid solution with the hole side of the tank and the other side away from the hole side of the reaction tank.

That is, a water absorbing member such as a disposable diaper has a basic structure in which a flat plate-shaped absorber is sandwiched between a water permeable sheet member and a non-water permeable sheet member. In this case, the adhesive portions between the water-permeable sheet member and the non-water-permeable sheet member are cut off on the two opposite sides of the water absorbing member so that the absorbent body is exposed to the outside, and a cut-out for the acid solution to flow in is formed on the water absorbing paper. Further, the absorbent body is wound with the sheet member at both ends of the winding opening. The absorber formed in a cylindrical shape can retain its shape by the non-water-permeable sheet member. When this is housed vertically in the reaction tank and bubbles are ejected from the bottom of the reaction tank, the bubbles that have entered the absorber through the opening on the lower surface are not blocked by the non-permeable sheet member and do not escape in the lateral direction. Pass in the upward direction. For this reason, the fresh acid solution uniformly passes through the superabsorbent resin carried on any part of the air felt, and the reaction can be rapidly and uniformly advanced. The opening may be a cutout, a continuous hole, an intermittent hole, or the like.

The measuring apparatus for carrying out the method for measuring the content of superabsorbent resin in the absorbent body according to the present invention is as follows: a) A plurality of the cylindrical samples are loaded and the samples are
Sample supply means for supplying one by one, b) a reaction tank capable of accommodating one sample and having a large number of gas ejection holes in the inner wall, and c) a solution for injecting a predetermined amount of acid solution into the reaction tank Injecting means, d) solution collecting means for collecting the acid solution in contact with the superabsorbent resin from the reaction tank, and e) quantifying the excess hydrogen ion in the acid solution collected by the solution collecting means. And a back titration means for calculating the content of the super absorbent polymer based on the measurement result.

As the sample supply means, for example, a rack provided with a tray on which a plurality of cylindrical samples are arranged in a plane with an appropriate inclination is suitable. According to this,
When the sample located at the lowest point in the tray is taken out, the sample above it rolls down in sequence, and the sample can always be taken out at the same position.

Further, it is preferable that the solution collecting means collects a predetermined amount of the acid solution by taking out the acid solution into a titration container placed on the measuring table of the weight measuring means.

In this case, it is preferable to update the titration container every time one sample is measured.
It is advisable to further include a container supply means for supplying each one individually.

In the measuring apparatus having the above structure, a transfer means is provided in the vicinity of the sample supply means, the reaction tank, the back titration means, the weight measurement means, and the container supply means, and the transfer means supplies the sample supply. An operation of gripping one sample from the means and charging it into the reaction tank, an operation of gripping one titration container from the container supply means and placing it on the measuring table of the weight measuring means, and It is more preferable that an operation for holding the titration container into which the acid solution has been injected by the solution collecting means from the measurement table and loading the container for back titration is performed.

That is, the transfer means is, for example, an industrial robot as is generally known, and its arm performs expansion / contraction, vertical movement, and rotation operations, and the hand attached to the tip of the arm is vertical and horizontal. The object is grasped in the direction. The arm is installed almost in the center on the fixed base,
The necessary sample and titration container are transferred between the sample supply means, the reaction tank, the back titration means, the weight measurement means, and the container supply means arranged around the sample supply means. The operation of the arm and hand is sequence-controlled in accordance with the program input to the computer so as to be linked to the processing in each of the above means. As a result, a series of measurement operations from sample supply to calculation of measurement results are automated.

Further, in the above measuring device, in order to collect the remaining acid solution and absorber in the reaction tank after the acid solution is taken out by the solution collecting means, the absorber is stored and the acid solution is stored. A bucket with a mesh to pass through,
A filter for filtering the acid solution that has passed through the mesh, a liquid receiving tank that stores the acid solution that has passed through the filter, and a solution for injecting a neutralizing liquid that neutralizes the acid solution that has accumulated in the liquid receiving tank. It is preferable to have a configuration including a waste container having an injection pipe.

According to this, the solid matter discharged in the measurement, that is, the absorbent body after the superabsorbent resin is eluted,
The waste liquid, that is, the acid solution obtained by reacting the superabsorbent resin, is separated and collected. Particularly, since the acid solution is neutralized in the waste container, the risk of waste liquid is reduced.

The reaction treatment of the superabsorbent resin in the reaction tank usually takes longer than the titration treatment by the back titration means. Therefore, in order to efficiently perform the automatic measurement, it is preferable to provide a plurality of reaction tanks and perform the processing in each reaction tank at a different time. For example, while titrating the acid solution collected from the first reaction tank in which the reaction treatment has been completed, the first reaction tank is washed, and at the same time, other samples of other samples are collected in the second reaction tank. Execute the reaction process. By increasing the number of reaction vessels according to the processing capacity of the back titration means, it is possible to efficiently measure a large number of samples.

[0028]

The measuring method according to the present invention has the following remarkable effects as compared with the conventional method. (1) Since the amount of superabsorbent resin itself is back-titrated by titrating the amount of excess hydrogen ions when the superabsorbent resin is brought into contact with an acid solution, the superabsorbent resin content is low. Quantification can be performed with the same high accuracy in both cases and in many cases. (2) At the time of titration, since a normal pH meter electrode may be used instead of the inaccurate sodium ion measurement electrode, stable measurement can be performed, and it is sufficient to create a calibration curve once a day. is there. (3) In the reaction step, the bubbles always pass through the inside of the absorber, so that the superabsorbent resin in the absorber is always given the opportunity to come into contact with the fresh acid solution. Therefore, the reaction rate of the super absorbent polymer is high, and the measurement efficiency can be improved. (4) It is not necessary to peel the absorber from the backsheet or cut it into small pieces. Therefore, the work for preparing the sample can be completed in a short time, and no skill is required. Moreover, scissors for cutting are not required, and the running cost of measurement can be saved. (5) A stirrer is not required, and work for removing pulp entwined with the paddle is not required. Therefore, the work efficiency is improved, and the measurement is easily automated. (6) Since the absorbent body may be immersed in the acid solution while being sandwiched between the back sheet and the top sheet, particles of the super absorbent polymer in the absorbent body do not scatter and the measurement accuracy is improved.

Further, the measuring device according to the present invention has the following remarkable effects. (7) It is possible to automate all the measurement steps after producing the cylindrical sample. That is, since it is only necessary to manually perform an operation that does not require skill such as preparation of a cylindrical sample and disposal of the sample after measurement, the measurement cost is low and the measurement efficiency is significantly improved.

[0030]

EXAMPLES Examples of the method for measuring the content of the super absorbent resin in the absorbent body according to the present invention will be described below with reference to FIGS. FIG. 1 is a flow chart showing the working steps of this measuring method, FIG. 2 is a schematic diagram illustrating the working procedure of the sample preparation step, and FIG. 3 is a schematic diagram illustrating the working procedure of the step.

First, as a preparatory step, a sample is molded into a state suitable for immersion in an acid solution in a reaction step described later (step S1). That is, the top sheet 105 and the back sheet 106 of the diaper are cut off at their longitudinally bonded portions by a cutting means such as scissors, and the leg gathers 108 are removed (see FIG. 2A). Next, both ends in the longitudinal direction of the tissue 104 enclosing the absorbent body layer 103 are cut with scissors to open (see FIG. 2B). Furthermore, it was wrapped in a tissue 104 (strictly sandwiched)
The absorber layer 103 in the state is wound with the top sheet 105 and the back sheet 106 attached, so that the openings are at both end surfaces (see FIG. 2C). As a result, the tissue 104 is formed on both end faces of the sample 109 formed into a cylindrical shape.
Is opened and the inside absorber layer 103 is exposed. The sample 109 is housed in a cylindrical sample tube 110 having an inner diameter slightly larger than the sample diameter and open at both end surfaces so as to be easily stored and transported (see FIG. 2D). .

Next, the sample 10 produced as described above.
The reaction step of contacting the AGM particles 102 contained in the absorber layer 103 of No. 9 with the acid solution is performed (step S2). For this reason, preferably, as shown in FIG. 3 (a), a cylindrical reaction tank having a diameter and a depth sufficient for the whole sample 109 to be dipped and a large number of holes 31 having an appropriate diameter at the bottom of the inner wall. Use 30. An air supply pipe 32 for sending the air jetted from the hole 31 is arranged at the side of the reaction tank 30.

After accommodating the sample 109 in the empty reaction tank 30 (step S21), while blowing air at a proper flow rate from the hole 31, hydrochloric acid having a predetermined concentration is added from above to the reaction tank 3
Inject into 0. Hydrochloric acid is poured in a predetermined amount sufficient to immerse the entire sample 109 (step S22). The air ejected from the holes 31 becomes bubbles and enters the inside of the absorbent layer 103 through the opening of the tissue 104 on the lower surface of the sample 109, passes through the inside of the absorbent layer 103 in the upward direction, and exits through the opening of the tissue 104 on the upper surface (see FIG. 3 (b)). Since the absorber layer 103 is securely held by the back sheet 106, it is hardly deformed by the pressure of bubbles. Further, since the back sheet 106 does not pass the solution, the bubbles that have entered the inside of the absorber layer 103 through the cuts of the tissue 104 pass straight up. Therefore, during bubbling, the AGM particles 102 held at any position in the absorber layer 103 are always exposed to fresh hydrochloric acid and react at a high speed (step S23).

After bubbling is carried out for a predetermined time sufficient for the AGM particles 102 in the absorber layer 103 to react almost completely, the next quantitative determination step is performed (step S).
3). First, a predetermined amount of hydrochloric acid having undergone the reaction treatment with AGM is taken out to the titration beaker (step S31). For this sampling, a suction pipe may be inserted into the hydrochloric acid from the upper part of the reaction tank 30 to suck the hydrochloric acid, or a sampling port having an opening / closing valve may be provided below the reaction tank 30. good. In any case, the hydrochloric acid is filtered using a filter such as a metal mesh in order to remove the pulp fibers of the air felt mixed in the hydrochloric acid.

Then, the amount of hydrogen ions remaining in the hydrochloric acid collected in the titration beaker is titrated (step S32).
That is, a sodium hydroxide solution containing a hydroxyl cation of a predetermined concentration is added dropwise until the hydrochloric acid becomes neutral.
Then, the amount of sodium hydroxide solution required to neutralize the hydrochloric acid is obtained, and the amount of hydrogen ions remaining in the hydrochloric acid is calculated from the amount of this sodium hydroxide solution. The amount of hydrogen ions consumed by the reaction of AGM is calculated back from the known amount of hydrogen ions contained in the same volume of hydrochloric acid before the reaction of AGM. Then, the weight of the AGM is calculated based on the amount of hydrogen ions (step S33).

To carry out the above titration, AGM
The hydrochloric acid previously contains an excess of hydrogen ions so that the hydrogen ions remain sufficiently after the reaction of. For example, in order to measure one common infant diaper, a reaction is performed using about 100 ml of hydrochloric acid having a concentration of 0.3 N, and 10-100 ml of hydrochloric acid after the AGM reaction is performed.
It is advisable to collect in a titration beaker and perform titration of the excess hydrogen ion with a sodium hydroxide solution having a concentration of 0.1N.

Such titration (that is, back titration)
The treatment and the AGM weight calculation can be carried out by combining a commercially available automatic titrator (for example, a Mettler automatic titrator of Japan Siber Hegner Co., Ltd.) and a personal computer.

Next, an automatic measuring device for automatically performing the above-described measuring work will be described with reference to FIGS. FIG. 4 is a schematic configuration diagram showing the configuration of an embodiment of the automatic measuring device.

A sample tube 11 is provided around a fixed base 1 having a rotary base 3 having a retractable arm 2 as a center.
Three sample racks 4a, 4b, 4c for horizontally storing a large number of samples 109 stored in 0, an electronic balance 5 having a measuring table on the upper surface, and three cylindrical reaction tanks 30
a, 30b, 30c, a titration device 6, a beaker feeder 7 including a large number of titration beakers, and a hand exchanging unit 8 provided with a plurality of hands 9 of different sizes to be attached to the tip of the arm 2 are arranged. ing. 3 reaction tanks 30
Above the a, 30b, and 30c, multipurpose nozzles 50a, 50b, and 50c that are vertically movable independently of each other are provided. These multipurpose nozzles 50a, 50b, 50c are
The solution sampling pipes 11 each having an electromagnetic on-off valve are connected, and the solution sampling pipes 11 from the multipurpose nozzles 50a, 50b, 50c join and are connected to the suction port side of the solution sampling pump 12. A pipe extending from the discharge port side of the solution sampling pump 12 is connected to a nozzle installed on the upper part of the electronic balance 5.

The multipurpose nozzles 50a, 50b, 50
A hydrochloric acid injection pipe 13 having an electromagnetic on-off valve is also connected to c, and the hydrochloric acid injection pipes 13 from the multipurpose nozzles 50a, 50b, 50c join and are connected to the discharge port side of the hydrochloric acid injection pump 14. The inlet side of the hydrochloric acid injection pump 14 is
It reaches the hydrochloric acid measuring container 16 placed on the measuring table of the electronic balance 15 through the pipe. Hydrochloric acid is poured into the hydrochloric acid measuring container 16 from the hydrochloric acid storage tank 18 by the operation of the hydrochloric acid measuring pump 17. Further, although not shown, the multipurpose nozzles 50a, 50b, 50c are supplied with cleaning water through separate pipes each having an electromagnetic opening / closing valve.

The reaction tanks 30a, 30b and 30c are constructed so as to be independently inverted about the horizontal axis. A waste container 19 is arranged below the waste container 19, and the waste container 19 is supplied with a sodium hydroxide solution for neutralizing hydrochloric acid from the neutralization liquid tank 21 by operating the neutralization liquid transfer pump 20. In addition, the waste container 19
The waste liquid neutralized in 1 is discharged to the outside from the waste liquid pipe 22. Further, a beaker dump port 23 and a sample tube dump port 24 are provided at predetermined positions of the fixed base 1, and a recovery bucket (not shown) is installed below both dump ports 23, 24.

In addition to the components shown in FIG. 4, peripheral devices such as a personal computer and a printer are provided to control the operation of each of the above-mentioned parts, and the results obtained by the titration device 6 are calculated to calculate the AGM. The content is calculated, and statistical processing or the like is executed as necessary.

FIG. 5 is a side view showing the appearance of one sample rack. Three trays 41 capable of accommodating twelve samples 109 are fixed to the frame 42 with an appropriate inclination as shown in FIG. End face 41 of one tray 41
In a, sample 1 is obtained by the operation of the hand 9 as described later.
A notch is formed so that 09 is gripped in the horizontal direction.
When the sample 109 at the lowermost end is taken out by the hand 9, the sample 109 on it is rolled down and set at a position where it can be held by the hand 9. In this example, 1
A maximum of 36 samples 109 can be stored in one sample rack, and the measurement device shown in FIG. 4 can store a maximum of 108 samples 109. Can be changed.

FIG. 6 is a perspective view showing the appearance of the waste container. The waste container consists of three reaction tanks 30a, 3
Corresponding to the positions of 0b and 30c, three buckets 91 having a relatively large mesh at the bottom are provided. A two-stage filter 92 for surely collecting the pulp fibers of the air felt 101 is provided below the bucket 91, and the solution (hydrochloric acid reacted with AGM) that has passed through the two-stage filter 92 is received at the bottom. It collects in the liquid tank 93. A neutralizing solution injection pipe 94 into which a sodium hydroxide solution is injected from the outside, and a waste liquid conduit 22 for discharging the waste liquid to the outside are provided in the liquid receiving tank 93.
Is connected.

The operation of the automatic measuring device having the above-mentioned structure will be described below along with the measuring work steps already described. First,
Cylindrical samples 109 prepared manually or by machines in the preparation process are sample racks 4a, 4b, 4c.
Is stored in. The arm 2 attaches a hand 9 for holding the sample 109 at the hand exchange section 8 to the tip thereof, and then one sample 109 stored in the sample tube 110 from the sample rack 4a (or 4b, 4c). Take it out. And that sample 109
Empty reaction tank 30a (or 30
b, 30c), the hand 9 is vertically rotated on the reaction tank 30a, and the sample 109 is slid from the sample tube 110 and put into the reaction tank 30a.

Sample 109 is sample tube 110
Is held relatively tightly inside the sample tube 11
Even if the sample 109 does not slide down even if 0 is set to the vertical direction, the sample 109 is pushed out by the multipurpose nozzle 50a (or 50b, 50c) descending from above and falls. After that, the arm 2 rotates and moves onto the sample tube disposal port 24 while the hand 9 holds the empty sample tube 110, and drops the sample tube 110 into the collection bucket through the sample tube disposal port 24. Sample tubes 110 collected in collection bucket
Will be reused for later measurements.

Next, the multipurpose nozzle 50a descends right above the reaction tank 30a containing the sample 109. Then, the hydrochloric acid injection pump 14 is activated, and the hydrochloric acid measuring container 1
The hydrochloric acid stored in 6 is injected into the reaction tank 30a from the multipurpose nozzle 50a through the hydrochloric acid injection pipe 13. A predetermined weight of hydrochloric acid is stored in the hydrochloric acid measuring container 16 in advance by the electronic balance 15.

When the injection of hydrochloric acid into the reaction tank 30a is started, the ejection of air from the hole 31 at the bottom of the reaction tank 30a is also started. Of course, a gas other than air, such as nitrogen or oxygen gas, may be used. When the total amount of the hydrochloric acid in the hydrochloric acid measuring container 16 has been injected into the reaction tank 30a, the sample 109 is completely immersed in the hydrochloric acid, and as described above, the absorbent layer 1 is formed by bubbles.
The reaction of AGM particles 102 in 03 is promoted. The bubbling time can be set as appropriate, but as will be described later, it is possible to react the AGM particles in an amount generally used for a disposable diaper almost in a few minutes.

During the bubbling, the arm 2 performs a change operation to the hand 9 for holding the titration beaker in the hand exchanging section 8. Then, after exchanging the hand, one titration beaker is taken out from the beaker feeder 7 and placed on a predetermined position on the measuring table of the electronic balance 5. The beaker feeder 7 has a structure in which a large number of plastic beakers are stacked and held, and when the bottommost beaker is taken out, the upper beaker is set at the position of the previous beaker.

When the predetermined bubbling time ends in the reaction tank 30a, the ejection of air from the hole 31 is stopped. And the multipurpose nozzle 5 by the solution sampling pump 12
The solution (hydrochloric acid after the reaction of AGM) in the reaction tank 30a is sucked through 0a and injected into the titration beaker previously prepared on the measuring table of the electronic balance 5. According to the reading of the measurement value of the electronic balance 5, the injection is stopped when a predetermined amount of the solution is collected in the titration beaker.

Next, the hand 9 holds the titration beaker containing this solution, transfers it to the beaker mounting table of the titration device 6, and mounts it there. When the placement of the titration beaker is detected, the titration device 6 sucks the solution in the titration beaker into the buret and starts titration of the amount of hydrogen ions in the solution.

On the other hand, the reaction tank 30a after a predetermined amount of the solution has been collected is inverted with the horizontal axis as the rotation axis after the multipurpose nozzle 50a is lifted. As a result, the reaction tank 30a
The remaining solution and the sample 109 drop into the waste container 19. Falling sample 109 is bucket 9
The solution stays at 1, and the solution is filtered by the two-stage filter 92 and then stored in the liquid receiving tank 93. A sodium hydroxide solution is injected from the neutralization liquid injection pipe 94 to be neutralized, and discharged as a waste liquid to the outside through the waste liquid pipe line 22. A pH electrode is attached to the waste liquid pipe 22, and the injection amount of sodium hydroxide is adjusted while monitoring that the waste liquid is almost neutral.

The emptied reaction tank 30a is again inverted about the horizontal axis to return to the original state, and the multipurpose nozzle 50a descends into the reaction tank 30a. Then, the cleaning water is ejected from the multipurpose nozzle 50a. At this time, the pulp fibers adhering to the outer surface of the tip of the multipurpose nozzle 50a are blown off by the water pressure of the washing water, and the multipurpose nozzle 50a is blown away.
A itself is washed, and at the same time, the pulp fiber and hydrochloric acid drops adhering to the inner wall of the reaction tank 30a are washed away. Then, when the predetermined cleaning time ends, the multipurpose nozzle 50a
Moves up to an unobtrusive position, the reaction tank 30a is again turned around the horizontal axis, and the wash water accumulated in the reaction tank 30a is discarded in the waste container 19.

The beaker for titration, which has become unnecessary after the titration is completed in the titration device 6, is gripped by the hand 9 and moved from the beaker mounting table of the titration device 6 to the beaker disposal port 23. Then, it is dropped into the lower recovery bucket through the beaker disposal port 23.

In the personal computer provided in association with the titration device 6, the AG in one sample is determined based on the consumption amount of hydrogen ions back-titrated by the titration device 6.
The weight of M is calculated.

The measurement of one sample 109 is completed by the above series of operations. In this measurement work, the titration process in the titration device 6 is normally completed in about 1 to 2 minutes, whereas the reaction process requires several minutes or more. For this reason,
3 reaction tanks 30 for efficient measurement work
bubbling in a, 30b, and 30c is performed with a temporal shift so that bubbling of another sample is performed in another reaction tank while titrating the solution in the reaction tank in which the reaction treatment is completed in the titration device 6. Then, programming is performed to control the entire sequence.

Next, the structure and operation of the multipurpose nozzle will be described with reference to FIGS. 7 and 8. The multipurpose nozzle 50 is
A substantially spherical tip portion 51 having a large number of holes, and a tip portion 51
Fine mesh filter 52 for covering the inside of the cylinder, cylindrical cylinder 53 connected to the tip portion 51, cylinder 5
3, a solution collecting pipe 11, a hydrochloric acid injecting pipe 13 and a washing water injecting pipe 54 connected to each other. This multipurpose nozzle 50
Has multiple functions as follows.

First of all, the sample 109 is added to the reaction tank 30.
The multipurpose nozzle 50 pushes the sample 109 out of the sample tube 110 when the sample is accommodated in the sample tube 110 (see FIG. 7A). That is, since the thickness of the air felt 101 differs depending on the sample, there are some that are loosely inserted and some that are tightly inserted in the sample tube 110. In the latter case, the hand 9 is the sample tube 110.
Although the sample 109 does not slide off from the sample tube 110 only by making the sample vertical, the sample 109 falls into the reaction tank 30 by being pushed out by the multipurpose nozzle inserted from the upper end surface of the sample tube 110.

Secondly, the reaction tank 30 is installed through the multipurpose nozzle.
Hydrochloric acid is added dropwise to the solution (see FIG. 7B). Hydrochloric acid injection tube 13
When hydrochloric acid is supplied to the cylinder 53 via the, the hydrochloric acid drips from the hole of the tip portion 51 in a shower shape. Therefore, the reaction tank 30 is filled with hydrochloric acid while the hydrochloric acid rapidly permeates the entire absorber layer 103 of the sample 109.

Thirdly, the reaction tank 30 is supplied through the multipurpose nozzle.
The solution (hydrochloric acid after reaction of AGM) is sucked from (see FIG. 8 (a)). In this case, the multipurpose nozzle is lowered until the tip portion 51 thereof is sufficiently immersed in hydrochloric acid, and the solution sampling tube 1
Aspirate solution through 1. The pulp fiber of the air felt 101 mixed in the solution is completely removed by the two-stage filter including the hole of the tip portion 51 and the filter 52 having a finer mesh.

Fourth, the used reaction tank 30 is washed (see FIG. 8B). In this case, the multipurpose nozzle is lowered into the reaction tank 30, and washing water (for example, distilled water from which impurities are removed) is supplied with high water pressure through the washing water injection pipe 54. The washing water spouts vigorously from the hole of the tip portion 51, and the pulp fibers attached to the hole are blown out during the solution suction process. Further, the cleaning water is used to wash away pulp fibers and solution residue attached to the inner wall of the reaction tank 30. Of course, the solution drops remaining in the cylinder 53 are also washed away.

Next, the effect of the bubbling method using the reaction tank in the measuring device according to the above description will be concretely described according to an experimental example. FIG. 9 shows the results obtained by measuring the reaction rate of 10 samples over time, using a relatively large infant diaper as a sample. For comparison, the measurement was also performed when bubbling was not performed under the same conditions. The reaction rate immediately after the start of bubbling varied greatly depending on the sample, but at 5 minutes after the start of bubbling, all exhibited a very high reaction rate of 98% or more.
Thus, according to the bubbling method, AGM can be reacted with hydrochloric acid quickly and reliably.

While the embodiments of the present invention have been illustrated and described above, it will be apparent to those skilled in the art that various other variations and modifications can be made without departing from the spirit and scope of the present invention. Accordingly, such variations and modifications are encompassed within the scope of the appended claims and are within the scope of the invention.

[Brief description of drawings]

FIG. 1 is a flowchart showing working steps in an embodiment of a method for measuring the content of a superabsorbent resin in an absorber according to the present invention.

FIG. 2 is a schematic diagram illustrating a work procedure of a sample preparation process of this example.

FIG. 3 is a schematic diagram illustrating a work procedure of a reaction process of this example.

FIG. 4 is a schematic configuration diagram of an embodiment of an automatic measuring device for the content of a superabsorbent resin in an absorber according to the present invention.

FIG. 5 is a side view of a sample rack according to this embodiment.

FIG. 6 is a perspective view showing the external appearance of a waste container according to this embodiment.

FIG. 7 is a schematic diagram for explaining the operation of the multipurpose nozzle in this embodiment.

FIG. 8 is a schematic diagram for explaining the operation of the multipurpose nozzle in this embodiment.

FIG. 9 is a graph showing the effect of the bubbling method in the measuring method of the present invention.

FIG. 10 is a configuration diagram of a paper diaper to be measured.

[Explanation of symbols]

 1 ... Fixed base 2 ... Arm 3 ... Rotation base 4a, 4b, 4c ... Sample rack 5, 15 ... Electronic balance 6 ... Titrator 7 ... Beaker feeder 8 ... Hand exchange part 9 ... Hand 11 ... Solution sampling tube 12 ... Solution Sampling pump 13 ... Hydrochloric acid injection pipe 14 ... Hydrochloric acid injection pump 16 ... Hydrochloric acid measuring container 19 ... Waste container 20 ... Neutralizing solution transfer pump 30a, 30b, 30c ... Reactor 50a, 50b, 50c ... Multipurpose nozzle

 ─────────────────────────────────────────────────── ─── Continuation of front page (71) Applicant 592043805 ONE PROCTER & GANBLE PLAZA, CINCINNATI, OHIO, UNITED STATES OF AMERICA (72) Inventor Kyoko Ida 2-24 Shinsenri Nishimachi Toyonaka City A3-207

Claims (11)

[Claims] 1. A measuring method for measuring the content of a superabsorbent resin in an absorbent body, comprising contacting the superabsorbent resin with an acid solution containing a known amount of hydrogen ions, and then measuring the superabsorbent resin. In the absorber characterized in that the excess hydrogen ions except the hydrogen ions consumed by displacing the alkali metal of the alkali metal base to be constituted are quantified, and the amount of the superabsorbent resin is calculated based on the measurement result. Method for measuring content of super absorbent polymer. 2. An alkaline solution is added until the acid solution in contact with the superabsorbent resin becomes neutral, and the surplus hydrogen ions are quantified from the amount of the alkaline solution at that time. Item 2. A method for measuring the content of a superabsorbent resin in the absorbent body according to Item 1. 3. When the superabsorbent resin is brought into contact with an acid solution, the absorber is immersed in a reaction tank filled with the acid solution, gas is ejected from the holes of the reaction tank to generate bubbles, and the bubbles are generated. The method for measuring the content of the superabsorbent polymer in the absorbent body according to claim 2, wherein the absorbent body is passed through the inside of the absorbent body. 4. A method for measuring the content of a superabsorbent resin in an absorbent body wrapped in a predetermined casing, the method comprising:
An opening is provided in the side where the absorber is exposed, and one of the openings is placed on the hole side of the reaction tank and the other is separated from the hole side of the reaction tank to immerse the absorber in the acid solution. The method for measuring the content of a superabsorbent resin in the absorbent body according to claim 3, characterized in that. 5. A cylindrical sample is produced such that the absorber is wound up so that the openings are at both ends, and the sample is held in the reaction tank while being inclined upward. Item 5. A method for measuring the content of a super absorbent polymer in the absorbent body according to item 4. 6. A measuring apparatus for carrying out the method for measuring the content of a superabsorbent resin in an absorbent body according to claim 5, wherein a) a plurality of the cylindrical samples are loaded and the sample is
Sample supply means for supplying one by one, b) a reaction tank capable of accommodating one sample and having a large number of gas ejection holes in the inner wall, and c) a solution for injecting a predetermined amount of acid solution into the reaction tank Injecting means, d) solution collecting means for collecting the acid solution in contact with the superabsorbent resin from the reaction tank, and e) quantifying the excess hydrogen ion in the acid solution collected by the solution collecting means. And a back titration means for calculating the content of the super absorbent polymer based on the measurement result, and a device for measuring the content of the super absorbent resin in the absorbent body, comprising: 7. The solution collecting means collects a predetermined amount of the acid solution by taking out the acid solution into a titration container placed on a measuring table of the weight measuring means. An apparatus for measuring the content of a super absorbent polymer in the absorbent body according to 1. 8. The apparatus for measuring the content of a superabsorbent resin in an absorbent body according to claim 7, further comprising container supply means for supplying the titration container. 9. A transfer means is provided in the vicinity of the sample supply means, the reaction tank, the back titration means, the weight measuring means, and the container supply means, and the transfer means is one unit from the sample supply means. An operation of gripping a sample and loading it into the reaction tank, an operation of gripping one titration container from the container supply means and placing it on the measuring table of the weight measuring means, and from the measuring table The content of the superabsorbent resin in the absorbent body according to claim 8, characterized in that the operation of holding the titration container into which the acid solution has been injected by the solution collecting means and loading it into the back titration means is performed. Measuring device. 10. In order to discard the remaining acid solution and the absorber in the reaction tank after the acid solution is collected by the solution collecting means, a mesh for storing the absorber and passing the acid solution is used. A bucket provided with the filter, a filter for filtering the acid solution that has passed through the mesh, a liquid receiving tank that stores the acid solution that has passed through the filter, and a neutralizing liquid that neutralizes the acid solution that has accumulated in the liquid receiving tank. 10. The apparatus for measuring the content of superabsorbent resin in the absorbent body according to claim 9, further comprising a waste container having an injection pipe for injecting. 11. The apparatus for measuring the content of a superabsorbent resin in an absorbent body according to claim 10, wherein a plurality of the reaction tanks are provided, and the treatments in the respective reaction tanks are performed at different times.