JP7439829B2 - Inorganic particles for fibers and their manufacturing method - Google Patents

Description

The present invention relates to inorganic particles for textiles and a method for producing the same, and can be suitably used as a deodorant for textiles.

Inorganic particles such as zirconium phosphate particles are used as deodorants.For example, as more comfortable living environments are required, they are used in deodorant sheets, deodorant curtains, deodorant filters, and to eliminate sweat odor and aging odor. "Deodorizing products" such as clothing, bedding, etc. that have deodorizing functions for such things have come into circulation.

As a conventional deodorant for textiles, the one described in Patent Document 1 is known.
Patent Document 1 discloses α-zirconium phosphate and/or α-phosphorus having a median diameter of 0.2 to 0.7 μm, a maximum particle diameter of 5.0 μm or less, and a D10 diameter of 0.1 μm or more. Deodorants for textiles containing titanium oxide are described.

Patent Document 1: Japanese Patent Application Publication No. 2018-178313

Conventionally, a method is known in which zirconium phosphate is applied by post-processing after weaving, but there are problems such as the deodorizing function cannot be maintained for a long time because it is removed by washing or the like. Further, by performing the above-mentioned post-processing, there are problems such as deterioration of productivity.
On the other hand, by kneading inorganic particles such as zirconium phosphate particles during fiber spinning, for example, if a textile is manufactured using yarn that has various functions such as deodorizing function due to the inorganic particles, it is possible to have deodorizing function. It has the advantage of being able to manufacture textile products without reducing productivity.
In addition, regarding the sustainability of the deodorizing function, etc., since inorganic particles are embedded in the fibers, it is better to incorporate inorganic particles during spinning than to apply zirconium phosphate etc. during post-processing. We believe that this can be maintained for a long period of time.

Furthermore, with the increase in spinning speed aimed at improving the productivity of the spinning process, the level of requirement for eliminating coarse particles has increased. Therefore, in the case of conventional inorganic particles for textiles where the generation of coarse particles cannot be suppressed during the particle manufacturing process, polymer filters used to eliminate coarse particles that cause yarn breakage during the spinning process in which inorganic particles are kneaded are insufficient. The present inventors have discovered a problem in that the frequency of yarn breakage during spinning increases and the productivity in the spinning process decreases.

The problem to be solved by the present invention is to provide inorganic particles for fibers that have a low thread breakage rate during spinning, that is, a small number of thread breakages per unit time, and a method for producing the same.

Means for solving the above problems include the following aspects.
<1> Inorganic particles for fibers in which the content of coarse particles with a particle size exceeding 1.562 μm measured by an electrical detection band method is 1,500 ppm or less.
<2> Inorganic particles for fibers, in which the content of coarse particles with a particle size exceeding 1.562 μm measured by a flow particle image analysis method is less than 300 ppm.
<3> The inorganic particles for fibers according to <1> or <2>, wherein the inorganic particles for fibers are zirconium phosphate particles, titanium phosphate particles, hydrotalcite particles, or zirconium hydroxide particles.
<4> The inorganic particles for fibers according to any one of <1> to <3>, wherein the inorganic particles for fibers are zirconium phosphate particles.
<5> The inorganic particles for fibers according to <1>, wherein the content of coarse particles with a particle size exceeding 1.562 μm measured by a flow particle image analysis method is less than 300 ppm.
<6> The inorganic particles for fibers according to any one of <1> to <5>, having a median diameter of 0.2 μm to 1.0 μm.
<7> The inorganic material for textiles according to any one of <1> to <6>, wherein the content of coarse particles with a particle size exceeding 2.148 μm measured by an electrical detection band method is 5 ppm or less. particle.
<8> The inorganic particles for fibers according to any one of <1> to <7>, which do not contain coarse particles having a particle size exceeding 2.148 μm as measured by an electrical detection band method.
<9> The inorganic particle for textiles according to any one of <1> to <8>, which is a deodorant for textiles.
<10> The method for producing inorganic particles for fibers according to any one of <1> to <9>, which includes a step of removing coarse particles in the inorganic particles by dry classification.
<11> The method for producing inorganic particles for fibers according to <10>, wherein the dry classification is performed using a swirling air classifier.

According to the present invention, it is possible to provide inorganic particles for fibers with a low thread breakage rate during spinning, and a method for producing the same.

7 is a diagram showing nine coarse particles detected by image analysis in Example 1 in order from the largest to the largest. FIG. 9 is a diagram showing nine coarse particles detected by image analysis in Comparative Example 1 in order from the largest to the largest. FIG.

Although the description of the constituent elements described below may be made based on typical embodiments of the present invention, the present invention is not limited to such embodiments. In addition, in this specification, "~" is used to include the numerical values described before and after it as a lower limit value and an upper limit value.
In the numerical ranges described step by step in this specification, the upper limit value or lower limit value described in one numerical range may be replaced with the upper limit value or lower limit value of another numerical range described step by step. good. Further, in the numerical ranges described in this specification, the upper limit or lower limit of the numerical range may be replaced with the value shown in the Examples.
In the present invention, "mass %" and "weight %" have the same meaning, and "mass parts" and "weight parts" have the same meaning.
Furthermore, in the present invention, a combination of two or more preferred embodiments is a more preferred embodiment.
The content of the present invention will be explained in detail below.

(Inorganic particles for textiles)
In the first embodiment of the inorganic particles for fibers of the present invention, the content of coarse particles having a particle size exceeding 1.562 μm measured by an electric detection band method is 1,500 ppm or less, preferably 300 ppm or less. The number is less than ppm.
Further, a second embodiment of the inorganic particles for fibers of the present invention is a coarse particle having a particle size exceeding 1.562 μm as measured by a flow particle image analysis method (also referred to as "particle dynamic image analysis method"). The content is less than 300 ppm.
In this specification, when it is simply described as "inorganic particles for fibers of the present invention", unless otherwise specified, it refers to both the first embodiment and the second embodiment.
Moreover, the inorganic particles for textiles of the present invention can be suitably used as a deodorant for textiles.

In conventional methods for producing inorganic particles, for example, even if inorganic particles ideally free of coarse particles can be produced by optimizing the conditions of the reaction process, the drying process and pulverization process downstream of the reaction process Therefore, there is a possibility that new coarse particles will be generated, and it may not be possible to produce inorganic particles from which coarse particles have been removed as a final product.

One method is to finally remove coarse particles by sieving, but there is a limit to the removal of coarse particles by the mesh of the sieve.

Sharpening the particle size distribution indirectly reduces the number of coarse particles, but for example, it was found that the coarse particles that cause thread breakage during spinning of polyester fibers are coarse particles contained in ppm order. .
Furthermore, even if the median diameter D50 is made small in order to reduce the number of coarse particles, for example, at the stage of addition to polyester resin or kneading, particles with small particle diameters tend to re-agglomerate and become coarse particles, resulting in thread It has been found that the polymer filter used to remove coarse particles causes breakage, and that the differential pressure increases, reducing productivity.

In general, laser diffraction particle size analyzers have a wide measurement range in which particle size distribution can be measured, but they cannot detect coarse particles on the order of ppm in number units with particle diameters in the range of 1.5 μm to 5 μm. It is. In addition, laser diffraction particle size distribution analyzers require sophisticated technology, such that measurement results vary depending on the manufacturer of the measuring device even for the same sample, and measurement results can vary significantly depending on the settings of measurement conditions such as refractive index. There was a problem with the development.

Conventionally, the removal of coarse particles by classification has been disclosed as a general theory, but there is a need to accurately confirm how to remove coarse particles by classification, to what level, and whether coarse particles are actually removed. is not specifically disclosed at all.
Therefore, for example, there is currently no technology to solve the problem of thread breakage during fiber spinning.

As a result of extensive studies, the present inventors have found that by adopting the above structure, it is possible to provide inorganic particles for fibers with a low rate of yarn breakage during spinning.
Although the mechanism of action of this excellent effect is not clear, it is estimated as follows.
The electrical detection band method or the flow particle image analysis method has excellent detectability as a method for confirming coarse particles with a particle size exceeding 1.562 μm, so the content of the coarse particles measured by these methods is It is estimated that by setting the amount to 1,500 ppm or less in the former case and less than 300 ppm in the latter case, it is possible to obtain inorganic particles for fibers with a low thread breakage rate during spinning.

Hereinafter, the inorganic particles for fibers of the present invention will be explained in detail.

The inorganic particles for fibers of the present invention are not particularly limited as long as they are inorganic particles used for fibers, but include zirconium phosphate particles, titanium phosphate particles, hydrotalcite particles, zirconium hydroxide particles, alumina particles, silicic acid particles, etc. Preferably, they are aluminum particles, copper silicate particles, zinc silicate particles, manganese silicate particles, cobalt silicate particles, or nickel silicate particles, and zirconium phosphate particles, titanium phosphate particles, hydrotalcite particles, Alternatively, zirconium hydroxide particles are more preferable, and from the viewpoint of deodorizing properties, zirconium phosphate particles are particularly preferable.
Furthermore, the inorganic particles for fibers of the present invention may contain impurities other than those mentioned above, and may also contain known additives used for fibers.
Among these, the inorganic particles for fibers of the present invention preferably contain 90% by mass or more of the inorganic component, more preferably 95% by mass or more, and preferably 99% by mass or more. Particularly preferred.

The method of measuring the particle size of inorganic particles by the electric detection band method in the present invention is carried out by the following method.
Measurement is performed using Multisizer 3 manufactured by Beckman Coulter Co., Ltd., which is a measuring device (Coulter counter) using the electric detection band method.
The aperture size is set to 30 μm, and approximately 50,000 particles are measured, and the distribution among them is measured based on the number of particles, and the content of coarse particles having a particle size exceeding 1.562 μm is measured.

In addition, the method for measuring the particle size of inorganic particles by the flow type particle image analysis method in the present invention is carried out by the following method.
A flow type particle image analyzer FPIA-3000S manufactured by CIMEX Corporation (currently Malvern Panalytical Division of Spectris Corporation) is used.
Inorganic particles are added to pure water from which foreign matter has been removed through a filter so that the dispersion concentration is 0.05% by mass, and dispersed for 3 minutes using an ultrasonic dispersion device. The obtained dispersion liquid is dropped into the flow type particle image analyzer, approximately 30,000 inorganic particles are measured and analyzed, and the content of coarse particles with a particle size exceeding 1.562 μm is determined. .
Further, the upper limit of particle diameter measurement is preferably 100 μm.

In the first embodiment of the inorganic particles for fibers of the present invention, the content of coarse particles having a particle size exceeding 1.562 μm measured by an electrical detection band method is 1,500 particles from the viewpoint of suppressing yarn breakage. ppm or less, preferably 300 ppm or less, more preferably 200 ppm or less, even more preferably 100 ppm or less, particularly preferably 50 ppm or less, and 25 ppm or less. Most preferably, it is less than ppm.

In the second embodiment of the inorganic particles for fibers of the present invention, the content of coarse particles having a particle size exceeding 1.562 μm measured by a flow particle image analysis method is 300 ppm from the viewpoint of suppressing yarn breakage. It is preferably less than 100 ppm, more preferably less than 10 ppm, even more preferably less than 1 ppm, and the particle size measured by flow particle image analysis is 1. It is particularly preferable that coarse particles exceeding 562 μm are not included.

In the inorganic particles for fibers of the present invention, the content of coarse particles with a particle size exceeding 2.148 μm measured by an electric detection band method is preferably 5 ppm or less from the viewpoint of suppressing yarn breakage. It is more preferable that the amount is 1 ppm or less, and it is particularly preferable that coarse particles having a particle size exceeding 2.148 μm as measured by an electric detection band method are not included.
In addition, in the inorganic particles for fibers of the present invention, the content of coarse particles with a particle size exceeding 2.148 μm measured by a flow particle image analysis method is 5 ppm or less from the viewpoint of suppressing yarn breakage. is preferable, it is more preferable that it is 1 ppm or less, and it is particularly preferable that coarse particles having a particle size exceeding 2.148 μm as measured by a flow particle image analysis method are not included.

Furthermore, from the viewpoint of inhibiting yarn breakage, it is preferable that the inorganic particles for fibers of the present invention do not contain coarse particles having a particle size exceeding 3 μm as measured by an electrical detection band method.
Furthermore, from the viewpoint of suppressing yarn breakage, the inorganic particles for fibers of the present invention preferably do not contain coarse particles having a particle size exceeding 3 μm as measured by a flow particle image analysis method.

The inorganic particles for fibers of the present invention have a median diameter D50 of 0.1 μm to 1.2 μm, as measured by laser diffraction method, from the viewpoint of exhibiting more functional effects such as yarn breakage suppressing property and deodorizing effect. It is preferably from 0.2 μm to 1.0 μm, and particularly preferably from 0.5 μm to 0.9 μm.

In addition, the inorganic particles for textiles of the present invention have a cumulative particle size of 99.9% by number D99.9 measured by the electrical detection band method, and exhibit better functional effects such as yarn breakage prevention and deodorizing effect. From the viewpoint of this, it is preferably 1.562 μm or less, more preferably 0.5 μm to 1.55 μm, and particularly preferably 1.0 μm to 1.50 μm.

(Method for producing inorganic particles for textiles)
The method for producing the inorganic particles for fibers of the present invention is not particularly limited as long as the inorganic particles for fibers of the present invention can be produced, but from the viewpoint of removability of the coarse particles, the inorganic particles are Preferably, the method includes a step of removing coarse particles (also referred to as a "dry classification step").

The classification method for removing coarse inorganic particles may be either dry classification or wet classification. In wet classification, if the final product is sold in powder form, a drying process is required after classification, and even if coarse particles are removed before drying, they will solidify and agglomerate again during the drying process. This may occur in some cases. Therefore, dry classification is preferred since it does not require a drying step after classification, has a low possibility of caking and agglomeration, and can simplify the manufacturing process.

Examples of the dry classifier include a mechanical type and a swirling airflow type, but the classifier is not limited as long as it can classify coarse particles. In a mechanical classifier, the mechanical classification rotor rotates at high speed, and mechanical precision is required to prevent vibration, so there is a limit to the classification point. Specifically, when the particle size to be excluded as coarse particles is in the range of 1.5 μm to 5 μm, a mechanical classifier has its limits and may not be able to exclude coarse particles with high accuracy.
Further, in classification by mechanical rotation of a classification rotor, metal contamination may occur due to wear due to sliding of metal parts. From the above point of view, it is preferable to carry out the dry classification using an air classifier using a swirling flow (swirling air classifier) that does not have a mechanically rotating part in its structure. For example, a swirling air classifier described in International Publication No. 2011/132301 is preferably mentioned.

The pressure and amount of the high-pressure gas to be blown onto the inorganic particles during dry classification are not particularly limited, but the pressure is preferably 0.1 MPa to 1.0 MPa.
Further, the air volume during dry classification is not particularly limited, but is preferably 1 m ³ /min to 10 m ³ /min.

The method for producing inorganic particles for fibers of the present invention may include steps such as a pulverizing step of pulverizing inorganic particles or aggregated particles of inorganic particles, and a sieving step of sieving the inorganic particles.
The timing of performing the dry classification step is not particularly limited, and for example, it may be performed before or after the pulverization step and the sieving step, or it may be performed both before and after the pulverization step and the sieving step. After the particle size is once adjusted in the crushing step and the sieving step, dry classification can be performed to further eliminate coarse particles.
Moreover, after implementing dry classification, a crushing process and a sieving process can be implemented.
Considering that coarse particles may be newly generated in the pulverizing step and the sieving step, the dry classification step is preferably performed after the pulverizing step and the sieving step.

The classification point in the dry classification step may be set appropriately as desired, but for example, since the single fiber of the fiber is about 10 μm, when adding or kneading inorganic particles into the resin forming the fiber, spinning From the viewpoint of suppressing yarn breakage during thread breakage, it is preferable to exclude coarse particles with a particle size of more than 3 μm, more preferably to exclude coarse particles with a particle size of more than 2.148 μm, and coarse particles with a particle size of more than 1.562 μm. It is particularly preferred to exclude.

The method for producing inorganic particles for fibers of the present invention may include a step of producing inorganic particles.
The inorganic particles used in the method for producing inorganic particles for fibers of the present invention may be prepared inorganic particles such as commercially available products, or manufactured inorganic particles.
There are no particular limitations on the method for producing inorganic particles, and known methods can be used.
As an example, a method for producing zirconium phosphate particles will be described below.

Zirconium phosphate in the present invention is produced by a known method using zirconium oxychloride, oxalic acid, and phosphoric acid as starting materials. For example, it can be produced by the method described in JP-A-60-103008 or JP-A-2018-178313. However, the method for producing zirconium phosphate is not limited to this.

The obtained zirconium phosphate may be dried after solid-liquid separation or without solid-liquid separation. Specific methods for solid-liquid separation include a filter press or a pressure filtration machine, and the water-containing cake (sludge) after solid-liquid separation is dried. Suitable methods for drying the water-containing cake include a paddle dryer, a conical dryer, a vibration dryer, an inverted conical stirring dryer, and the like. Examples of methods for drying without solid-liquid separation include spray dryers, ball-filled fluidized bed dryers, jet turbo dryers, and the like.
When zirconium phosphate undergoes solid-liquid separation, it becomes clay-like, has strong adhesive properties, and is difficult to handle. Therefore, it is preferable to dry the zirconium phosphate particles without solid-liquid separation to obtain zirconium phosphate particles.

The dried zirconium phosphate particles may or may not be subjected to crushing, pulverization, or sieving treatment. In order to adjust the particle size to be uniform, it is preferable to crush or pulverize and further pass through a sieve.

Moisture in the inorganic particles for fibers of the present invention can be determined by mixing the inorganic particles with a raw material resin for synthetic fibers such as polyester resin using an extruder or the like before spinning. Water may evaporate during heating and kneading in an extruder, and the raw material resin may foam. In order to prevent foaming, the moisture content of the inorganic particles for fibers of the present invention is preferably 1% by mass or less, more preferably 0.6% by mass or less.

(fiber)
The fiber of the present invention is a fiber containing the inorganic particles for fibers of the present invention, and is preferably a deodorizing fiber containing the inorganic particles for fibers of the present invention.
There are no particular limitations on the method for producing fibers containing the inorganic particles for fibers of the present invention, and known methods can be used.
For example, there may be mentioned a method of kneading the inorganic particles for fibers of the present invention into fibers and spinning them.

The fiber of the present invention is preferably a resin fiber, and more preferably a chemical fiber.
As the fiber resin that can be used, any known chemical fibers can be used.
Preferred specific examples of the material of the chemical fiber include polyester, polyurethane, nylon, rayon, acrylic resin, vinylon, and polypropylene. Among these, polyester, nylon, or acrylic resin is preferable, and polyester is more preferable.
Preferred specific examples of polyester include polyethylene terephthalate, polyethylene naphthalate, polytrimethylene terephthalate, and polybutylene terephthalate. Among them, polyethylene terephthalate is preferred.
These resins may be homopolymers or copolymers. In the case of a copolymer, there is no particular restriction on the polymerization ratio of each copolymer component.
The method of adding the inorganic particles for fibers of the present invention to the resin is not particularly limited; for example, it may be added during the polymerization process of the resin, or it may be kneaded using an extruder using the resin after polymerization. .

The inorganic particles for fibers of the present invention can be preferably used as a deodorant for kneading into fibers.
In this case, a specific method for producing the deodorizing fibers includes a method of kneading the inorganic particles for fibers of the present invention into a molten liquid resin for fibers or a solution of a dissolved resin for fibers, and spinning this. .

The content of the inorganic particles for fibers of the present invention in the fibers of the present invention is not particularly limited.
Generally, if the content is increased, deodorizing properties can be more strongly exerted and can be sustained for a long period of time. The content of the inorganic particles for fibers of the present invention in the fiber of the present invention is preferably from 0.1 parts by weight to 3.0 parts by weight, and preferably from 0.5 parts by weight to 2.0 parts by weight, based on 100 parts by weight of the resin. More preferably, it is 0 parts by weight.

The deodorizing fiber using the inorganic particles for fibers of the present invention can be used in various fields that require deodorizing properties, such as underwear, stockings, socks, futons, duvet covers, cushions, blankets, carpets, It can be used in many textile products such as curtains, sofas, car seats, air filters, and clothing for nursing care.

EXAMPLES Hereinafter, the present invention will be explained in detail with reference to Examples, but the present invention is not limited thereto. In this example, "%" and "parts" mean "% by weight" and "parts by weight", respectively, unless otherwise specified.

The size of coarse particles, the number of coarse particles, the content of coarse particles relative to the effective N number, measurement of coarse particles by image analysis, and spinning after adding or kneading zirconium phosphate particles to polyester resin. The yarn breakage rate, which indicates the frequency of yarn breakage, was measured by the following method.

(1) Size of coarse particles, number of coarse particles The particle size of zirconium phosphate was measured using an electrical detection band method using a Multisizer 3 manufactured by Beckman Coulter Co., Ltd., which is a so-called Coulter counter.
The aperture size was set to 30 μm, 50,000 pieces were measured, and the distribution among them was measured based on the number of pieces.

(2) Concentration of coarse particles relative to effective N number As a result of measurement using Multisizer 3 manufactured by Beckman Coulter Co., Ltd., the cumulative number of particles of 1.562 μm or more and less than 2.148 μm was defined as coarse particles.
The concentration of coarse particles relative to the actually measured effective N number was calculated using the following formula.
Cumulative number of particles of 1.562 μm or more and less than 2.148 μm ÷ Actual measured effective N number x 100,0000 = Concentration ppm of cumulative coarse particles of 1.562 μm or more and less than 2.148 μm with respect to effective N number

(3) Measurement of coarse particles by flow-type particle image analysis (dynamic image analysis of particles) Measured with a flow-type particle image analyzer, FPIA-3000S manufactured by CIMEX Co., Ltd. (currently Malvern Panalytical Division of Spectris Co., Ltd.) did.
Powder was added to pure water from which foreign matter had been removed through a filter so that the dispersion concentration was 0.05%, and the powder was dispersed for 3 minutes using an ultrasonic dispersion device. The dispersion liquid was dropped into a flow type particle image analyzer, and approximately 30,000 particles were measured and analyzed.
A flow-type particle image analyzer sorted the detected particles in descending order of size, and measured the particle diameter of the largest particles and a photograph of the particles.

(4) Number of thread breakages A masterbatch was prepared in which 20% of the produced zirconium phosphate particles were blended with respect to 100% of a polyester resin (MA2101M, polyethylene terephthalate resin, manufactured by Unitika Co., Ltd.). Then, this masterbatch was mixed with regular polyester resin pellets not containing zirconium phosphate to adjust the concentration to 2% by weight. This was spun using a multifilament spinning machine at a spinning temperature of 275°C and a spinning speed of 500 m/min for 2 hours, and then stretched at 120°C to an elongation of 280% to 320%, containing zirconium phosphate particles. Polyester fibers were obtained.
At this time, as the oil agent, a water-soluble oil agent (Derion 6033 manufactured by Takemoto Yushi Co., Ltd., diluted 10 times with water) for ordinary polyester fiber spinning was used.
Continuous spinning was performed for 2 hours, and spinnability was evaluated according to the following evaluation method.
A: The number of thread breakages is 0 times/2 hours B: The number of thread breaks is 1 time/2 hours or more and 3 times/less than 2 hours C: The number of thread breaks is 3 times/2 hours or more and 6 times/less than 2 hours D: Thread breakage is 3 times/2 hours or more and 6 times/less than 2 hours The number of thread breaks is 6 times/2 hours or more and less than 10 times/2 hours E: The number of thread breaks is 10 times/2 hours or more F: Not evaluated

As a reference example, a method for producing zirconium phosphate particles will be shown.

(Reference example: Production of zirconium phosphate particles)
Put 3,611 kg of deionized water and 363 kg of 35% hydrochloric acid into a 6 m ³ reactor, add 603 kg of a 20% aqueous solution of zirconium oxychloride octahydrate containing 0.18% hafnium, and then dissolve 250 kg of oxalic acid dihydrate. Ta. While thoroughly stirring this solution, 275 kg of 75% phosphoric acid was added. This was heated to 98° C. over 2 hours, and stirred and refluxed for 12 hours. After cooling, the obtained precipitate was thoroughly washed with water and then dried at 105°C to obtain zirconium phosphate particles. This was crushed using a crusher. After that, it was subjected to sieving treatment. As a result of measuring the obtained zirconium phosphate particles using an X-ray diffraction device, it was confirmed that they were α-zirconium phosphate particles.
The α-zirconium phosphate particles were heated and dissolved with hydrofluoric acid and nitric acid, and elemental analysis was performed using an ICP (Inductively Coupled Plasma) emission spectrometer, followed by thermogravimetric differential thermal analysis. As a result, the composition formula was as follows:
Zr _0.99 Hf _0.01 H _2.03 (PO ₄ ) _2.01・0.05H ₂ O
Met.

(Example 1)
Zirconium phosphate particles produced according to Reference Example were classified using a classifier (Aerofine Classifier Model AC-20: manufactured by Nisshin Engineering Co., Ltd.). The air volume sucked by the suction blower was 2.5 m ³ /min. Here, the amount of air sucked by the suction blower corresponds to the amount of normal pressure gas sucked from between the guide vanes. Further, the angle of the guide vane was set to 80° (tangential direction).
The conditions for the high pressure gas ejected from the upper air nozzle were 0.7 MPa, and the conditions for the high pressure gas ejected from the lower air nozzle were 0.6 MPa.
The powder before classification was continuously fed 478 g in 13 minutes at 2 kg/h using a quantitative feeder.
After classification, 415 g of fine powder was recovered. The yield based on the amount input to the classifier was 86.8%. The finer powder obtained after classification was measured using a Coulter counter.
The aperture size was set to 30 μm, 50,000 pieces were measured, and the distribution among them was measured based on the number of pieces.
The median diameter D50 was 0.731 μm, and the median diameter D99.9 was 1.442 μm.
The number of coarse particles with a particle size of more than 1.562 μm and less than 2.148 μm was 15.
Further, no coarse particles with a particle size exceeding 2.148 μm were detected.
The concentration (content) for the actually measured effective N number of 51,008 is:
15÷51,008×1,000,000=294 ppm
Met. Detailed results for the coarse particle portion are shown in Table 1.

In addition, the particle size was measured by a flow particle image analysis method. Specifically, the particle size was measured using a flow type particle image analyzer FPIA-3000S manufactured by CIMEX Corporation (currently Malvern Panalytical Division of Spectris Corporation). The number of particles measured was 30,000. As a result, no coarse particles with a particle size exceeding 1.562 μm were observed.
The concentration with respect to the number of measured particles was 0 ppm.
The results are shown in Tables 1 and 2. Table 2 summarizes the nine particle sizes observed from the largest, and FIG. 1 shows the coarse particles detected by image analysis in order from the largest. Further, each numerical value shown in FIG. 1 represents the size (unit: μm) of each coarse particle.
In addition, when the number of yarn breakages was evaluated, the number of yarn breakages was 0 times/2 hours, indicating that spinning could be performed extremely stably.
The evaluation result for the number of thread breakages was A.

(Example 2)
Zirconium phosphate produced according to Reference Example was classified using a classifier (Aerofine Classifier Model AC-20, manufactured by Nisshin Engineering Co., Ltd.). The air volume sucked by the suction blower was 2.3 m ³ /min. Here, the amount of air sucked by the suction blower corresponds to the amount of normal pressure gas sucked from between the guide vanes. Further, the angle of the guide vane was set to 90° (tangential direction).
The conditions for the high pressure gas ejected from the upper air nozzle were 0.6 MPa, and the conditions for the high pressure gas ejected from the lower air nozzle were 0.6 MPa.
Before classification, 505 g of the powder was continuously fed in 15 minutes at 2 kg/h using a quantitative feeder.
After classification, 387 g of fine powder was recovered. The yield based on the amount input to the classifier was 76.6%.
The finer powder obtained after classification was measured using a Coulter counter.
The aperture size was set to 30 μm, 50,000 pieces were measured, and the distribution among them was measured based on the number of pieces.
The median diameter D50 was 0.719 μm, and the median diameter D99.9 was 1.366 μm.
The number of coarse particles with a particle size of more than 1.562 μm and less than 2.148 μm was 1.
Further, no coarse particles with a particle size exceeding 2.148 μm were detected.
The concentration (content) for the actually measured effective N number of 50,969 is:
1÷50,969×1,000,000=20 ppm
Met. Detailed results for the coarse particle portion are shown in Table 1.
In addition, when the number of yarn breakages was evaluated, the number of yarn breakages was 0 times/2 hours, indicating that spinning could be performed extremely stably.
The evaluation result for the number of thread breakages was A.

(Example 3)
In Example 2, classification was performed under the same conditions as in Example 2, except that 3,924 g of the powder before classification was continuously fed using a quantitative feeder at 2 kg/h for 120 minutes. After classification, 2911 g of fine powder was recovered. The yield based on the amount input to the classifier was 74.2%.
Incidentally, the coarse particles of the finer powder obtained after classification were measured using a Coulter counter (Multisizer 3 manufactured by Beckman Coulter, Inc.).
The aperture size was set to 30 μm, 50,000 pieces were measured, and the distribution among them was measured based on the number of pieces.
The median diameter D50 was 0.722 μm, and the median diameter D99.9 was 1.406 μm.
The number of coarse particles with a particle size of more than 1.562 μm and less than 2.148 μm was 9.
Further, no coarse particles with a particle size exceeding 2.148 μm were detected.
The concentration (content) for the actually measured effective N number of 51,121 is:
9÷51,121×1,000,000=176 ppm
Met. Detailed results for the coarse particle portion are shown in Table 1.
In addition, when the number of yarn breakages was evaluated, the number of yarn breakages was 0 times/2 hours, indicating that spinning could be performed extremely stably.
The evaluation result for the number of thread breakages was A.

(Comparative example 1)
The coarse particles of the zirconium phosphate produced according to the reference example were directly measured using a Coulter counter (Multisizer 3 manufactured by Beckman Coulter, Inc.) without dry classification.
The aperture size was set to 30 μm, 50,000 pieces were measured, and the distribution among them was measured based on the number of pieces.
The median diameter D50 was 0.760 μm, and the median diameter D99.9 was 1.606 μm.
The number of coarse particles with a particle size of more than 1.562 μm and less than 2.148 μm was 77.
Further, no coarse particles with a particle size exceeding 2.148 μm were detected.
The concentration (content) for the actually measured effective N number of 51,097 is:
77÷51,097×1,000,000=1,507 ppm
Met.

In addition, particle size was measured by image analysis using a flow type particle image analyzer FPIA-3000S manufactured by CIMEX Corporation (currently Malvern Panalytical Division of Spectris Corporation). The number of particles measured was 30,000. As a result, nine coarse particles with a particle size exceeding 1.562 μm were observed.
The concentration with respect to the number of measured particles was 9÷30,000×1,000,000=300 ppm.
The results are shown in Tables 1 and 2, and FIG. 2 shows nine coarse particles detected by image analysis in order from largest to largest. Further, each numerical value shown in FIG. 2 represents the size (unit: μm) of each coarse particle.
In addition, when the number of yarn breakages was evaluated, the number of yarn breakages was 1 time/2 hours or more and less than 3 times/2 hours, and yarn breakage occurred several times. The evaluation result of the number of thread breakages was B.

(Comparative example 2)
The powder on the coarse side after the dry classification carried out in Example 1 was collected, and the coarse particles were measured using a Coulter counter (Multisizer 3 manufactured by Beckman Coulter, Inc.).
The aperture size was set to 30 μm, 50,000 pieces were measured, and the distribution among them was measured based on the number of pieces.
The median diameter D50 was 0.770 μm, and the median diameter D99.9 was 1.661 μm.
The number of coarse particles with a particle size of more than 1.562 μm and less than 2.148 μm was 127.
Further, no coarse particles with a particle size exceeding 2.148 μm were detected.
The concentration (content) for the actually measured effective N number of 50,953 is:
127÷50,953×1,000,000=2,492 ppm
Met.
In addition, when the number of thread breakages was evaluated, thread breakage occurred frequently. The evaluation result for the number of thread breakages was F.

In Examples 1 and 2, from the measurement results of the finer powder after classification, the cumulative number of coarse particles with a particle size of 1.562 μm or more and less than 2.148 μm was 15 and 1, respectively. Compared to 77 particles before classification, there are fewer coarse particles, and the coarse particles can be removed.
In Example 3, even when the classification throughput of Example 2 was increased, the cumulative number of coarse particles with a particle size of 1.562 μm or more and less than 2.148 μm was as small as 9, and the coarse particles could be eliminated. It shows.

Comparative Example 1 is a case where zirconium phosphate particles that have not been subjected to classification treatment are measured using a Coulter counter, and the cumulative number of coarse particles with a particle size of 1.562 μm or more and less than 2.148 μm is as large as 77. It shows. It can be seen that without classification treatment, many coarse particles are contained.
In Comparative Example 2, the coarse particles of Example 1 were collected after the classification process.
Since it is on the coarse particle side, compared to the fine side after classification processing, the cumulative number of coarse particles with a particle size of 1.562 μm or more and less than 2.148 μm is 127, which is the case of Example 1. This is more than the 15 pieces on the finer side after classification. Furthermore, the number of coarse particles is greater than 77, which is the number of coarse particles in Comparative Example 1 without the classification process. This is the result of removing coarse particles by classification in Example 1, and indicates that the coarse particles that could be removed by classification could be separated and recovered as coarse particles after classification in Comparative Example 2.

In both measurements, the effective count of coarse particles was set at about 50,000, so it is possible to quantitatively compare the number of coarse particles.
Quantitative comparison of coarse particles is possible in units of ppm as the integrated concentration of coarse particles with particle diameters of 1.562 μm or more and less than 2.148 μm relative to the effective N number.

Furthermore, according to Table 2, in Example 1, in the measurement of coarse particles using the flow type particle image analyzer, the maximum coarse particle size detected was 1.494 μm, and the particle size was 1.562 μm or less. It can be seen that coarse particles with a particle size exceeding 1.562 μm can be removed by dry classification.
On the other hand, in Comparative Example 1, in the measurement of coarse particles using a flow-type particle image analyzer, the maximum detected coarse particle size was 9.443 μm, which indicates coarse particles with a particle size exceeding 1.562 μm. This shows that since dry classification was not performed, coarse particles with a particle size exceeding 1.562 μm could not be removed and were still contained.

As shown above, the inorganic particles for fibers of Examples 1 to 3, which are the inorganic particles for fibers of the present invention, have a lower number of thread breakages during spinning than the inorganic particles of Comparative Examples 1 and 2. Ta.

According to the method for producing inorganic particles for fibers of the present invention, trace amounts of coarse particles contained in ppm order that cannot be detected by a laser diffraction particle size analyzer can be easily removed.
Furthermore, when the inorganic particles for fibers of the present invention are kneaded into fibers such as polyester fibers, the frequency of yarn breakage during spinning can be reduced, productivity in the spinning process can be improved, and industrial It is very beneficial.

The disclosure of Japanese Patent Application No. 2019-083181 filed on April 24, 2019 is incorporated herein by reference in its entirety.
All documents, patent applications, and technical standards mentioned herein are incorporated by reference to the same extent as if each individual document, patent application, and technical standard was specifically and individually indicated to be incorporated by reference. , herein incorporated by reference.

Claims (6)

The content of coarse particles with a particle size exceeding 1.562 μm measured by a flow particle image analysis method is less than 300 ppm,
Inorganic particles for kneading into fibers, which are zirconium phosphate particles, titanium phosphate particles, hydrotalcite particles, or zirconium hydroxide particles. The inorganic particles for kneading fibers according to claim 1 , wherein the inorganic particles for kneading fibers are zirconium phosphate particles. The inorganic particles for kneading fibers according to claim 1 or 2, having a median diameter of 0.2 μm to 1.0 μm. The inorganic particles for kneading into fibers according to any one of claims 1 to 3 , which are deodorants for kneading into fibers. The method for producing inorganic particles for fiber kneading according to any one of claims 1 to 4 , which includes a step of removing coarse particles in the inorganic particles by dry classification. The method for producing inorganic particles for fiber kneading according to claim 5 , wherein the dry classification is performed using a swirling air classifier.