JP6853155B2 - Method for measuring the amount of silica adhered to synthetic fibers - Google Patents

Description

The present invention relates to a method for measuring the amount of silica adhered to a synthetic fiber to which an oil agent containing colloidal silica is attached.

Generally, synthetic fibers are oiled at the manufacturing stage. The components of this oil are prepared according to the purpose such as reduction of fiber surface resistance and static electricity removal, and applying a predetermined amount of oil without unevenness stabilizes the quality and improves the yield in fiber production. Leads to. Therefore, conventionally, an oil agent adhering to the fiber surface is extracted and measured with a solvent such as methanol or benzene (Non-Patent Document 1), the electrical resistance of the fiber is measured (Patent Document 1), or infrared rays are used. The amount of oil adhered to the oil is calculated by measuring optically using (Patent Document 2).
Further, as a method for measuring the silica concentration, there are a molybdenum yellow absorbance method (Non-Patent Document 2 and Patent Document 3) and a fluorescent X-ray spectrum method (Patent Document 4). It is used for water quality management in Japan.

Japanese Unexamined Patent Publication No. 6-287804 Japanese Unexamined Patent Publication No. 7-310223 JP-A-2010-151714 Japanese Unexamined Patent Publication No. 2002-107315

Japanese Industrial Standards JIS L1013 "Chemical Fiber Filament Thread Test Method" published in 2010, pp. 28-29 Japanese Industrial Standards JIS K0101 "Industrial Water Test Method" published in 1998, pp. 181-182

However, the amount of the synthetic fiber adhering to the oil agent is measured by extracting the oil agent with a solvent, electric resistance or infrared absorption, but no method for measuring the concentration of silica in the oil agent has been proposed. Further, as described above, as the silica concentration measurement, there are molybdenum absorptiometry and fluorescent X-ray spectrum method, but the former is for water containing ionic silica, and a thread to which an oil agent containing colloidal silica is applied. On the other hand, measurement is difficult even if the methods specified in Non-Patent Document 2 and Patent Document 2 are applied, and the latter is unsuitable for process control because the measurement takes time.

Therefore, an object of the present invention is to solve the above-mentioned problems and obtain a method for measuring the amount of silica adhered to synthetic fibers to which an oil agent containing colloidal silica is attached, which can be used for process control of a production process.

In order to achieve the above object, the present invention is a method for measuring the amount of silica adhered to a synthetic fiber to which an oil agent containing colloidal silica is attached, and is a step of preparing a standard sample containing the oil agent and a silica standard solution, and synthesis. The process of processing the fibers to prepare a fiber test sample, and the standard sample and the fiber test sample were mixed with ammonium molybdate under acidic conditions to develop a yellow color, and then the wavelength 1 in the range of 385 to 440 nm. A step of measuring the absorbance of at least two wavelengths of wavelength 2 in the range of 500 to 700 nm, a step of creating a calibration line from the measured absorbance of the standard sample of two wavelengths, and a step of preparing the measured absorbance of the fiber test sample of two wavelengths. , The step of calculating the amount of silica adhered from the calibration line, and the step of preparing the standard sample includes a process of mixing an oil agent, water and sodium hydrogen carbonate, boiling, and then adding a silica standard solution. The step of preparing the fiber test sample is a method for measuring the amount of silica adhered to a synthetic fiber, which comprises a process of mixing synthetic fiber containing an oil containing colloidal silica, water and sodium hydrogen carbonate and boiling the sample. Is the gist.
The step of measuring the absorbance preferably includes a step of coloring the color yellow, mixing the oxalic acid solution, and measuring the absorbance before the yellow color fades.
In the boiling treatment in the step of preparing the standard sample and the fiber test sample, the boiling time is preferably 60 minutes or more.
Moreover, it is preferable that the material of the sample container used when preparing the sample is PTFE.

According to the present invention, the amount of silica adhered to the synthetic fiber to which the oil agent containing colloidal silica is attached can be easily measured, and can be used for process control of the production process of the synthetic fiber.

It is a flowchart which shows the process outline of the method of measuring the silica adhesion amount of the synthetic fiber of this invention. It is a flowchart which shows an example of the process of preparing a standard sample in this invention. It is a flowchart which shows an example of the step of measuring the absorbance in this invention. It is a flowchart which shows an example of the process of preparing the fiber test sample in this invention. This is an example of the absorbance measurement result of a standard sample in the present invention. This is an example of a calibration curve in the present invention.

Hereinafter, the present invention will be described in detail.

The present invention is a method for measuring the amount of silica adhered to a synthetic fiber to which an oil agent containing colloidal silica is attached.

In the present invention, when simply described as "oil agent", it means an oil agent to be used for producing yarn without adding colloidal silica, and when it is described as "oil agent containing colloidal silica", it is colloidal. An oil agent to which silica is added and used for producing yarn is shown.

In the present invention, the absorbance of a standard sample containing an oil agent and a silica standard solution and a fiber test sample obtained by treating a synthetic fiber to which an oil agent containing colloidal silica is attached is measured, and the absorbance obtained from the standard sample is used. A calibration curve is created, and based on this calibration curve, the Si (silicon) content of the fiber test sample is calculated to calculate the amount of silica adhering to the synthetic fiber.

FIG. 1 is a flowchart showing a process outline of the method for measuring the amount of silica adhered to the synthetic fiber of the present invention. A standard sample is prepared, the absorbance of the standard sample is measured, and then a calibration curve is prepared based on the measurement result. Next, a fiber test sample of the synthetic fiber to be inspected is prepared, and the absorbance of the fiber test sample is measured. Based on the calibration curve and the measurement result of the absorbance of the fiber test sample, the amount of silica adhered to the synthetic fiber to be inspected is calculated.

Hereinafter, each step will be described.

<Standard sample preparation process>
The flowchart of FIG. 2 is an example of a process of preparing a standard sample. After mixing the oil, water and sodium hydrogen carbonate, it is preferably boiled for 60 minutes or more. The resulting liquid is then allowed to cool, neutralized and then diluted with water. A silica standard solution is prepared and mixed with the obtained diluent to prepare a plurality of standard samples having different silica concentrations.

Hereinafter, more specifically, preferred embodiments will be illustrated and described.
First, prepare the oil and the container. Weigh the oil and add to the container. As the container, it is preferable to use a container containing no silicon, and for example, a container made of PTFE, polyethylene, or platinum is preferably used. In particular, it is preferable to use a PTFE container because it is inexpensive and has excellent heat resistance.

Next, add water to the container. As the water, pure water is preferable, and ultrapure water is more preferable. The amount of water is not particularly limited, but is preferably an amount that allows the container to easily sink in the boiling bath, and may be appropriately adjusted according to the material and capacity of the container. For example, when a 200 ml PTFE container is used, 50 to 100 ml is preferable.

Next, sodium hydrogen carbonate is added to the container, and the container is allowed to stand in a boiling water bath and heated. If the amount of sodium hydrogen carbonate is too large, carbon dioxide gas is generated and foams, so it is preferable to set the amount so as not to foam. For example, it is preferable to add about 0.2 g of sodium hydrogen carbonate to 100 ml of water. The heating time is preferably at least 60 minutes or more.

The obtained liquid is allowed to cool, neutralized, and then diluted with water to prepare a blank solution for a standard sample. As the reagent used for neutralization, an inorganic acid such as hydrochloric acid or sulfuric acid can be preferably used. The water used for dilution is preferably pure water, more preferably ultrapure water.

Silica standard solutions having several concentrations such as 0, 1, 1.5, 3, 6 mg / l are placed in separate containers, and blank solutions for standard samples are added to prepare silica solutions, which are used as standard samples. ..

<Absorbance measurement process of standard sample>
In the present invention, when measuring the absorbance, the molybdenum yellow absorbance method using hexaammonium heptamolybdate is used from the viewpoint of ease of control in the manufacturing process.
FIG. 3 is an example of a flowchart for measuring the absorbance.
The standard sample is acidified and mixed with an ammonium molybdate solution under acidic conditions to develop a yellow color. If an oil containing phosphate ions is attached, mix the oxalic acid solution and measure the absorbance before the yellow color fades.

Hereinafter, a specifically preferred embodiment will be described.
Prepare a standard sample and add hydrochloric acid to make the standard sample acidic. At this time, the concentration of hydrochloric acid is preferably, for example, about 4% by mass with respect to the standard sample. The obtained sample may be acidic, but the pH at this time is preferably about 1.1 to 1.6 from the viewpoint of color development. When acidifying, an inorganic acid such as sulfuric acid or nitric acid can be used instead of hydrochloric acid.

The obtained standard sample under acidic conditions is added with an ammonium molybdate solution, mixed well, and allowed to stand for a predetermined time. As a result, a silicate molybdate complex (heteropoly acid) is generated, and the standard sample is colored yellow. As specific suitable conditions, for example, as an ammonium molybdate solution, a 107.5 g / l ammonium molybdate solution is used and allowed to stand for 5 minutes. The ammonium molybdate solution can be obtained by diluting hexaammonium hexaammonium tetrahydrate tetrahydrate with water.

Then, when the oil preparation contains phosphate ions, an oxalic acid solution is added, mixed, and allowed to stand. This suppresses the influence of phosphate ions.
The concentration of the oxalic acid solution can be appropriately set, but for example, by setting it to about 200 g / l, the influence of phosphate ions used as an oil agent used in ordinary yarn production when measuring the absorbance can be suitably suppressed. The standing time is set to a time during which the yellow color of the heteropoly compound does not fade. In the case of ordinary synthetic fibers, for example, 1 minute.

Then, the absorbance is measured using a spectrophotometer.

<Calibration curve creation process>
In the present invention, in order to at least suppress the influence of the oil agent and improve the accuracy of measuring the amount of silica adhered, a calibration curve is prepared by calculating each standard sample using at least two wavelengths. FIG. 5 is an example of the measurement result of the absorbance of the standard sample.

As the absorbance, at least two wavelengths of absorbance 1 having a wavelength of 385 to 440 nm and wavelength 2 having a wavelength of 500 to 700 nm are measured. By measuring two wavelengths in this range, the influence of cloudiness due to the influence of the oil agent of the synthetic fiber can be suppressed, and the amount of silica adhered can be calculated accurately. This is because the absorbance due to silica can be accurately obtained by subtracting the absorbance in the wavelength band (wavelength 2) due to cloudiness from the absorbance in the yellow wavelength band (wavelength 1).

Next, an approximate curve is calculated from the absorbance of the obtained standard sample at each concentration, and a calibration curve is prepared. FIG. 6 is an example of a calibration curve in the present invention.

<Fiber test sample preparation process>
FIG. 4 is a flowchart showing an example of a process for preparing a fiber test sample.
In this step, synthetic fibers to which an oil containing colloidal silica is attached, water, and sodium hydrogen carbonate are mixed and preferably boiled for 60 minutes or more to convert the colloidal silica into ionic silica. Then, the obtained liquid containing ionic silica is allowed to cool, neutralized, diluted with water, and prepared to prepare a fiber test sample.

Hereinafter, preferred embodiments will be described in more detail.
First, a synthetic fiber and a container to which an oil containing colloidal silica is attached are prepared. Weigh synthetic fibers with colloidal silica attached and add to the container. As the container, it is preferable to use a container containing no silicon, and for example, a container made of PTFE, polyethylene, or platinum is preferably used. In particular, it is preferable to use a PTFE container because it is inexpensive and has excellent heat resistance.

Next, add water to the container. As the water, pure water is preferable, and ultrapure water is more preferable. The amount of water is not particularly limited, but is preferably an amount that allows the container to easily sink in the boiling bath, and may be appropriately adjusted according to the material and capacity of the container. For example, when a 200 ml PTFE container is used, 50 to 100 ml is preferable.

Next, sodium hydrogen carbonate is added to the container, and the container is allowed to stand in a boiling water bath and heated to ionize colloidal silica to obtain ionic silica. If the amount of sodium hydrogen carbonate is too large, carbon dioxide gas is generated and foams, so it is preferable to set the amount so as not to foam. For example, it is preferable to add 0.2 g of sodium hydrogen carbonate to 100 ml of water. In order to sufficiently ionize the colloidal silica, the heating time is preferably at least 60 minutes or more.

The obtained liquid containing ionic silica is allowed to cool, then neutralized and diluted with water to prepare a fiber test sample. As the reagent used for neutralization, an inorganic acid such as hydrochloric acid, sulfuric acid or nitric acid can be preferably used. The water used for dilution is preferably pure water, more preferably ultrapure water.

<Absorbance measurement process of fiber test sample>
FIG. 3 is an example of a flowchart for measuring the absorbance.
The standard sample is acidified and mixed with an ammonium molybdate solution under acidic conditions to develop a yellow color. If an oil containing phosphate ions is attached, mix the oxalic acid solution and measure the absorbance before the yellow color fades.

Hereinafter, a specifically preferred embodiment will be described.
Hydrochloric acid is added to the obtained fiber test sample to make the fiber test sample acidic. At this time, the concentration of hydrochloric acid is preferably, for example, about 4% by mass with respect to the standard sample. The obtained sample may be acidic, but the pH at this time is preferably about 1.1 to 1.6 from the viewpoint of color development. When acidifying, an inorganic acid such as sulfuric acid or nitric acid can be used instead of hydrochloric acid.

Next, an ammonium molybdate solution is added to the fiber test sample, mixed well, and allowed to stand for a predetermined time. As a result, a silicate molybdate complex (heteropoly acid) is generated, and the fiber test sample is colored yellow. As specific conditions, for example, as an ammonium molybdate solution, a 107.5 g / l ammonium molybdate solution can be used and allowed to stand for 5 minutes. The ammonium molybdate solution can be obtained by diluting hexaammonium hexaammonium tetrahydrate tetrahydrate with water.

Then, when the oil preparation contains phosphate ions, an oxalic acid solution is added, mixed, and allowed to stand. This suppresses the influence of phosphate ions.
The concentration of the oxalic acid solution can be appropriately set, but for example, by setting it to about 200 g / l, the influence of phosphate ions used as an oil agent used in ordinary yarn production when measuring the absorbance can be suitably suppressed. The standing time is set to a time during which the yellow color of the heteropoly compound does not fade. In the case of ordinary synthetic fibers, for example, 1 minute.

Next, the absorbance is measured using a spectrophotometer. For the absorbance, at least the absorbances of two wavelengths, wavelength 1 of 385-440 nm and wavelength 2 of 500-700 nm, which were used when preparing the calibration curve of the standard sample, are measured. As a result, the influence of cloudiness caused by the oil agent of the synthetic fiber can be suppressed, and the accuracy of measuring the silica adhesion concentration can be improved.

From the obtained absorbance and the calibration curve obtained using the standard sample, the Si content C (mg / l) of the fiber test sample was obtained, and the silica adhesion amount R (wt%) of the synthetic fiber was obtained by the following formula. Is calculated.

By calculating the silica adhesion amount of the synthetic fiber by the calculation using at least two wavelengths as described above, the silica adhesion amount of the synthetic fiber can be measured accurately, and it can be used for process control in the spinning process.

Next, the method for measuring the amount of silica adhered to the synthetic fiber to which the oil agent containing colloidal silica of the present invention is attached will be described more specifically with reference to Examples.

<Preparation of standard sample, measurement of absorbance, preparation of calibration curve>
1.0 ml of oil was weighed, placed in a PTFE beaker, and 75 ml of ultrapure water was added. Next, 0.2 g of sodium hydrogen carbonate was added, the beaker was immersed in a boiling water bath, and after the liquid in the beaker boiled, it was heated for 60 minutes. After allowing the beaker liquid to cool, 1.2 ml of 2N hydrochloric acid was added to neutralize the beaker liquid, and the pH of the beaker liquid was adjusted to 5. The entire amount of liquid in the beaker was transferred to a 100 ml flask made of PMP, and ultrapure water was added up to the marked line. The liquid in this flask was used as a stock solution for a blank solution. 150 ml of a stock solution for a blank solution was added to 150 ml of ultrapure water to prepare 300 ml of a blank solution. Prepare five 50 ml volumetric flasks, add 0, 45, 75, 150, 300 μl of silica standard solution with a concentration of 1000 mg / l, respectively, add the blank solution up to the marked line, and add concentrations of 0, 1, 1.5, 3, A 6 mg / l silica solution was prepared and used as a standard sample.

Next, 1 ml of 6N hydrochloric acid was added and shaken well, and then 2 ml of a 100 g / l ammonium molybdate solution (a solution in which 20 g of ammonium hexamolybdate tetrahydrate was dissolved in 200 ml of ion-exchanged water) was added and well. Shake and let stand for 5 minutes. Then, 1.5 ml of a 100 g / l oxalic acid solution (20 g of oxalic acid dihydrate dissolved in 200 ml of ion-exchanged water) was added, shaken, and allowed to stand for 1 minute. After allowing to stand for 1 minute, the absorbance at two wavelengths of 420 nm and 550 nm was measured using a spectrophotometer (U-3310, manufactured by Hitachi High-Tech Science Corporation). The measurement results are shown in FIG. An approximate curve was calculated from the absorbance of each of the obtained concentrations, and the calibration curve of FIG. 6 was created.

<Preparation of fiber test sample, measurement of absorbance, calculation of silica adhesion concentration>
A polyester fiber having 0.6% by mass of a spinning oil containing a phosphate ion-based component (not containing colloidal silica) and 1.4% by mass of an oil containing colloidal silica was prepared. The fibers to which the oil containing 0.2 g of colloidal silica was attached were weighed, placed in a PTFE beaker, and 75 ml of ultrapure water was added. Next, 0.2 g of sodium hydrogen carbonate was added, the PTFE beaker was immersed in a boiling water bath, and after the liquid in the beaker boiled, it was heated for 60 minutes to ionize colloidal silica and form an ion. It was made of silica. After allowing the beaker liquid to cool, 1.2 ml of 2N hydrochloric acid was added to neutralize the beaker liquid, and the pH of the beaker liquid was adjusted to 5. The entire amount of liquid in the beaker was transferred to a 100 ml volumetric flask made of PMP, and ultrapure water was added up to the marked line to prepare a fiber test sample.

25 ml of the fiber test sample was placed in a 50 ml volumetric flask, and ultrapure water was added up to the marked line. Next, 1 ml of 6N hydrochloric acid was added and shaken well, and then 2 ml of a 100 g / l ammonium molybdate solution (a solution in which 20 g of ammonium hexamolybdate tetrahydrate was dissolved in 200 ml of ion-exchanged water) was added and well. Shake and let stand for 5 minutes. Then, 1.5 ml of a 100 g / l oxalic acid solution (20 g of oxalic acid dihydrate dissolved in 200 ml of ion-exchanged water) was added, shaken, and allowed to stand for 1 minute. After allowing to stand for 1 minute, the absorbance at two wavelengths of 420 nm and 550 nm was measured using a spectrophotometer (U-3310, manufactured by Hitachi High-Tech Science Corporation).

The Si content C (mg / l) of the fiber test sample was measured from the obtained absorbance and the calibration curve obtained using the standard sample and found to be 2.670 mg / l. When the adhesion amount R (wt%) was calculated, it was 0.58 wt%.

According to the measuring method of the present invention, the silica adhering amount of the synthetic fiber to which the oil agent containing colloidal silica is attached can be efficiently measured. Therefore, the silica adhering amount can be practically controlled in the process control of the spinning process. Can be done.

Claims (4)

It is a method for measuring the amount of silica adhered to synthetic fibers to which an oil agent containing colloidal silica is attached.
The process of preparing a standard sample containing an oil agent and a silica standard solution, and
The process of processing synthetic fibers to prepare fiber test samples,
For the standard sample and the fiber test sample, after mixing ammonium molybdate under acidic conditions and coloring the color yellow, at least two wavelengths of wavelength 1 in the range of 385 to 440 nm and wavelength 2 in the range of 500 to 700 nm. The process of measuring the absorbance and
The process of creating a calibration curve from the absorbance of the measured two-wavelength standard sample, and
It includes a step of calculating the amount of silica adhered from the absorbance of the measured two-wavelength fiber test sample and the calibration curve.
The step of preparing the above standard sample includes a process of mixing and boiling an oil agent, water and sodium hydrogen carbonate.
A method for measuring the amount of silica adhered to a synthetic fiber, which comprises a process of mixing synthetic fiber to which an oil containing colloidal silica is attached, water and sodium hydrogencarbonate and boiling the fiber test sample. .. In the step of measuring the absorbance,
The method for measuring the amount of silica adhered to a synthetic fiber according to claim 1, further comprising a step of mixing a oxalic acid solution after coloring the yellow color and measuring the absorbance before the yellow color fades. The method for measuring the amount of silica adhered to a synthetic fiber according to claim 1 or 2, wherein the boiling time is 60 minutes or more in the boiling treatment in the step of preparing the standard sample and the fiber test sample. The method for measuring the amount of silica adhered to a synthetic fiber according to any one of claims 1 to 3, wherein the material of the sample container used when preparing the sample is PTFE.

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