JP3491174B2 - Method for measuring bulkiness of fiber assembly sheet, method for controlling bulkiness and apparatus therefor - 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 measuring the bulkiness of a fiber assembly sheet, a method for controlling the bulkiness, and an apparatus therefor.

[0002]

2. Description of the Related Art Precursor fibers for producing carbon fibers, activated carbon fibers and the like are subjected to a reaction in the state where the fibers are formed into an aggregate sheet. In this case, since the reactivity varies depending on the physical properties of the sheet (particularly bulkiness, air permeability, etc.), when the sheet properties become non-uniform, not only the quality of the product obtained will vary, but also the reaction during production will be excessive. It also progresses and causes trouble during manufacturing. Therefore, it is necessary to control not only the weight of the sheet but also the bulkiness of the sheet within a certain range to ensure its uniformity. Therefore, it is necessary to measure the bulkiness of the fiber sheet during the manufacturing process.

However, heretofore, there has been no method for detecting the bulkiness of the fiber sheet. For example, in the production of non-woven fabrics and spun yarns, in order to control the thickness of the sliver of the spun yarns, it is sufficient to increase / decrease the amount of cotton supplied, and it is not necessary to measure the sheet bulkiness itself.

Even if the bulkiness of a fiber assembly sheet is to be measured, it is difficult to measure it for the following reasons. That is, in the fiber assembly sheet, generally, the fiber arrangement of the sheet is likely to be coarse and dense, and unevenness occurs on the sheet surface at the single yarn fiber level when viewed in the direction perpendicular to the sheet surface. Therefore,
If the bulkiness of the sheet is to be measured accurately, then the irregularities must also be detected. Moreover, since the fiber assembly causes diffuse reflection, it is not easy to recognize the position of the unevenness. As described above, at present, a method for effectively measuring the bulkiness of the fiber assembly sheet has not been established.

[0005]

Therefore, the main object of the present invention is to provide a method for effectively measuring the bulkiness of a fiber assembly sheet. A further object of the present invention is to provide a method for controlling the bulkiness of the fiber assembly sheet.

[0006]

As a result of intensive studies to achieve the above object, the present inventors have found that the bulkiness of a fiber assembly sheet can be effectively measured by using an ultrasonic range finder, and The inventors have also found that the bulkiness of the fiber assembly sheet can be controlled by changing the charged state of the sheet using the measurement result, and have completed the present invention.

That is, the present invention relates to the following first to third inventions.

1. 1st invention When measuring the bulkiness of a fiber assembly sheet, the distance of the sheet surface from the said rangefinder is measured with an ultrasonic rangefinder, The bulkiness measuring method of a fiber assembly sheet characterized by the above-mentioned.

2. Second invention: A method for controlling the bulkiness of a fiber assembly sheet, which comprises changing the charged state of the fiber assembly sheet according to the change in the bulkiness of the fiber assembly sheet.

3. A third invention is characterized in that an ultrasonic range finder capable of measuring the bulkiness of the fiber assembly sheet is installed above the sheet conveying line, and the sheet static eliminator is provided to the range finder through a conversion / control device. A bulkiness control device for a fiber assembly sheet.

The first to third inventions will be described in detail below in order.

The method for measuring the bulkiness of a fiber assembly sheet of the first invention is characterized in that, when measuring the bulkiness of the fiber assembly sheet, the distance from the distance meter to the sheet surface is measured by an ultrasonic rangefinder. It is a thing. The type of ultrasonic rangefinder that can be used in the present invention is not particularly limited, and a commercially available one can be used as it is.

As a measuring method, for example, the distance (K) from the sheet floor surface to the distance meter is measured in advance, and then the distance (L) from the sheet surface (upper surface) of the conveyed sheet to the distance meter is measured. It is possible to continuously detect the bulkiness (h) of the sheet by measuring the value of () and obtaining the difference (K−L). In the measuring method of the present invention, virtually any fiber assembly can be applied. Especially, the single yarn diameter is 5 to 3
It is a fiber of about 0 μm and the weight of the sheet is usually 100.
A sheet of g / m ² or more, preferably 200 g / m ² or more can be suitably measured. The fibers may be either long fibers or short fibers.

Regarding the processing of the measurement results, only one measurement value may be used, but it is preferable to take the average value of the measurement values of two or more times. In particular, when measuring a fiber assembly sheet having a small sheet areal weight, it is preferable to reject the minimum part of the measured values or obtain a moving average for each number of measurements. In the present invention, the measurement error can be further reduced by measuring the thickness of the fiber assembly sheet at 5 mm or more.

The bulkiness control method of the fiber assembly sheet of the second invention is characterized in that the electrification state of the sheet is changed according to the change in the bulkiness of the fiber assembly sheet. The bulkiness of the fiber assembly sheet can be detected, for example, by the bulkiness measuring method according to the first invention.

The fiber assembly sheet is obtained, for example, by melt-spinning pitch and depositing it while sucking it on a conveyor, but in this case, the bulkiness of the sheet occurs. This is because the sheet itself is charged by air friction or the like during suction after spinning. When the bulkiness of the sheet occurs, the subsequent treatments and reactions such as fusion between fibers in the infusibilizing treatment and conveyance troubles will be hindered. Therefore, the bulkiness of the sheet can be maintained within a certain range by measuring the bulkiness of the sheet, detecting the increase / decrease, and changing the charged state (charge, charge amount, etc.) of the sheet according to the increase / decrease. Becomes

Specifically, the optimum bulkiness level is predicted from the reaction state in the infusibilizing step and the activating step of the fiber sheet,
The reference value of the sheet bulkiness is set in advance within the range below the level. When the sheet bulkiness is equal to or higher than the reference value, the sheet bulkiness can be controlled near the reference value by changing the charge state of the sheet in the static eliminator. The above-mentioned bulkiness level and reference value may be appropriately set according to the physical properties of the fibers used, spinning conditions, and the like.

For example, in the case of a precursor for producing a pitch-based carbon fiber sheet, the sheet is positively charged by friction with air due to suction, and a charge gradient is generated between the front surface and the back surface of the sheet, resulting in a non-charged state. Compared with this, there is a portion where the bulkiness becomes large. When a sheet having such unevenness in bulkiness is subjected to infusibilizing treatment, not only troubles such as interfiber fusion occur but also a part of the sheet is attracted to the sheet conveying belt side due to electrification, and the sheet itself is conveyed. Will also cause problems. Therefore, after appropriately setting the optimum bulkiness level and the reference value as described above, when the sheet bulkiness is equal to or higher than the reference value, the sheet is negatively charged in accordance with it, thereby reducing the charging gradient. The bulkiness can be eliminated to reduce the bulkiness of the sheet, and the bulkiness of the obtained fiber sheet can be made uniform.

In a bulkiness control device for a fiber assembly sheet according to a third aspect of the invention, an ultrasonic range finder capable of measuring the bulkiness of the fiber assembly sheet is installed above the sheet conveying line, and the distance eliminator is equipped with a sheet static eliminator. Is provided via a conversion / control device. Here, the distance meter can also measure the sheet in a matrix in the vertical and horizontal directions by moving the sheet in the width direction of the traveling sheet to perform measurement.

An outline of an example of a manufacturing system including the device of the present invention is shown in FIG. In FIG. 1, a yarn (2) discharged from a nozzle (1) passes through an opening cylinder (4) and is laminated as a fiber sheet (12) on a conveyor (11) while being sucked. The bulkiness of the sheet is measured on the conveying line, and the conversion / control device (6) detects the increase / decrease of the bulkiness, and the charge eliminating device (7) changes the charged state of the sheet according to the increase / decrease. As shown in FIG. 1, the static eliminator is preferably installed above the last roller of the conveyor or immediately above the last roller. As the static eliminator, a known static eliminator used for manufacturing synthetic fibers or the like can be used as it is. Further, as the ultrasonic distance meter and the conversion / control device, commercially available devices can be applied as they are.

[0021]

According to the bulkiness measuring method of the present invention, since the ultrasonic distance meter is used, the bulkiness of the sheet can be continuously and effectively measured without directly touching the fiber sheet.

According to the bulkiness control method and the apparatus therefor of the present invention, since the bulkiness of the sheet can be quantified, the operating conditions can be specified (predicted), and the bulkiness of the sheet can be arbitrarily controlled. That is, since the sheet bulkiness can be made uniform by using the measurement result of the sheet bulkiness, the subsequent treatment (for example, infusibilizing treatment of the precursor fiber for carbon fiber production) can be performed reliably and efficiently. It can be carried out.

As described above, the measuring method, the controlling method and the apparatus thereof according to the present invention make it possible to greatly improve the production efficiency in the production of carbon fiber or the like on an industrial scale.

[0024]

EXAMPLES Examples will be shown below to clarify the characteristics of the present invention.

Example 1 The bulkiness of a pitch fiber sheet was continuously measured by the measuring method of the present invention.

After spinning the pitch continuously, the basis weight is 5
A pitch fiber sheet of 00 g / m ² and a fiber diameter of 20 μm was obtained.

Next, the pitch fiber sheet (sheet width 2
For m), while moving an ultrasonic range finder (“UD-310” manufactured by Keyence Corporation) in the sheet width direction, the sheet length and the sheet bulk are continuously set to 6 at 20 cm intervals in the width direction.
The time was measured. As a result, the maximum value obtained is 35.8.
mm, the minimum was 15.2 mm, and the average value was 25.5 mm. The measured value was output every 20 seconds while processing the average value of 60 times as one data.

Example 2 An activated carbon fiber sheet was manufactured while continuously controlling the sheet bulkiness by using the measuring method, controlling method and apparatus of the present invention.

With respect to a pitch fiber sheet obtained by melt-spinning 8 spindles with a constant discharge amount per unit area of pitch, its bulkiness was measured by the same method as in Example 1, while detecting increase / decrease of the bulkiness of the sheet. The bulkiness was controlled using the apparatus shown in FIG. It has been found that the optimum bulkiness level in the fiber sheet is within 50 mm from the reaction in the infusible and activation steps. Therefore, in the conversion / control unit, the standard value of the sheet bulk is set to 40 mm, the removal voltage in the case of the standard value is set to -25 Kv, and the removal voltage is changed by 5 Kv for each displacement of the sheet bulk of 5 mm. Was controlled so as to have an inverse correlation with the removal voltage, whereby a sheet whose bulkiness was controlled in the range of 35 to 45 mm was obtained.
Such a controlled sheet was subjected to infusibility / activation treatment,
No trouble occurred during infusion, and the fluctuation rate CV of the specific surface area of the activated fiber could be 10%.

Comparative Example 1 An activated carbon fiber sheet was produced in the same manner as in Example 2 except that the bulkiness of the sheet was not controlled and the same pitch as in Example 2 was used. As a result, the bulkiness of the obtained sheet is 35-5.
The range of 5 mm, the fluctuation rate of the specific surface area of the activated fiber is 15
%, Which is considerably higher than that in the case of Example 2.

[Brief description of drawings]

FIG. 1 is a diagram showing an outline of an example of a manufacturing system including an apparatus of the present invention.

[Explanation of symbols]

1 ... Nozzle 2 ... Thread 3 ... Suction gun 4… Open fiber cylinder 5 ... Ultrasonic range finder 6 ... Conversion / control device 7 ... Static eliminator 8 ... Device of the present invention 9 ... Suction machine 10 ... roller 11 ... transport conveyor 12 ... Fiber sheet

─────────────────────────────────────────────────── ─── Continuation of front page (56) Reference JP-A-63-3211 (JP, A) JP-A-63-75510 (JP, A) JP-A-1-298216 (JP, A) JP-A 64-- 97216 (JP, A) JP-B 47-24966 (JP, B1) (58) Fields investigated (Int.Cl. ⁷ , DB name) D06H 3/10 G01B 17/00

Claims (5)

(57) [Claims] 1. A sheet by changing the electrification state of the sheet according to the change in the bulkiness of the sheet.
A method for controlling the bulkiness of a fiber assembly sheet, characterized in that the bulkiness of the sheet is maintained within a certain range . 2. A bulkiness level is predicted from a reaction state of a precursor fiber sheet for carbon fiber production in an infusibilizing step and an activating step, and when the level is equal to or higher than a reference value in a range below the level, the charged state of the sheet. The bulkiness control method according to claim 1, wherein 3. The sheet is given a negative charge when the value is equal to or higher than a reference value in a range of a bulkiness level or lower.
2. The bulkiness control method described in 2 . 4. A bulky control method according to any one of claims 1 to 3 to change the charging state with a static eliminator. 5. An ultrasonic range finder capable of measuring the bulkiness of a fiber assembly sheet is installed above a sheet conveying line,
A sheet static eliminator is provided to the distance meter via a conversion / control device, and the conversion / control device increases the seat bulkiness.
Is detected, and the static eliminator will
A device for controlling the bulkiness of a fiber assembly sheet, characterized in that the electrification state of the sheet is changed .