JP7764672B2 - Dust suppressant treatment composition - Google Patents

Description

The present invention relates to a dust suppression treatment composition that has excellent dust suppression performance for dust-producing substances and also has excellent redispersibility. More specifically, the present invention relates to a dust suppression treatment composition for dust-producing substances that consists of an aqueous dispersion of a non-melt-flowable tetrafluoroethylene (hereinafter referred to as TFE) copolymer, in which the redispersion sedimentation rate of the TFE copolymer is 60% or less, and the content of perfluorooctanoic acid and its salts is less than 10 ppb.

The technology to suppress dust from dust-producing substances is important for daily life and industry from the viewpoints of health, safety, the environment, and other requirements.
As such a dust suppression technique, Patent Document 1 below proposes a method in which PTFE (TFE polymer) is mixed with a powdery substance and the mixture is subjected to a compression-shear action at a temperature of about 20 to 200°C to fibrillate the TFE polymer and suppress the generation of dust from the powdery substance.

The TFE polymers described in Patent Document 1 below include Teflon® 6 and Teflon® 30, which are TFE homopolymers in the form of fine powder or emulsion, and Teflon® 6C, which is a modified TFE polymer in the form of fine powder.

Furthermore, Patent Document 2 below proposes a dust suppression method using a stable aqueous emulsion containing 1.0% by mass or more of a hydrocarbon-based anionic surfactant relative to a TFE homopolymer (TFE polymer), and demonstrates that this method is effective in suppressing dust for powdery substances. According to Patent Document 2, TFE polymer particles are produced in the form of an aqueous emulsion by the emulsion polymerization method disclosed in Patent Documents 3 and 4 below, i.e., by forcing TFE into an aqueous medium containing a water-soluble polymerization initiator and an anionic surfactant with a fluoroalkyl group as the hydrophobic group (hereinafter referred to as a fluorine-containing emulsifier) as an emulsifier, followed by polymerization, with an emulsion stabilizer further added to enhance stability.

Furthermore, Patent Document 5 below describes a method for suppressing dust by using a dust suppression treatment composition consisting of an aqueous dispersion of a fluorinated polymer with a fluorinated emulsifier content of 50 ppm or less, which has a dust suppression effect and can suppress dust without concern for its impact on the environment.

However, the TFE polymer aqueous dispersions used as dust suppressant treatment compositions in these methods are prone to settling when left standing for long periods of time, and once settled, the TFE polymer solidifies and is difficult to redisperse. Furthermore, depending on the conditions of use, this can cause a decrease in the TFE polymer concentration in the TFE polymer aqueous dispersion, and there is a risk that the dust suppression effect inherent to the TFE polymer may not be fully exhibited.

Special Publication No. 52-32877 Japanese Patent Application Publication No. 8-20767 Special Publication No. 2010-509441 Special Publication No. 2010-509442 International Publication No. 2007/000812

In other words, the object of the present invention is to provide a dust suppression treatment composition that has excellent dust suppression effects, as well as excellent redispersibility of the non-melt-flowable TFE copolymer particles that are the solid content in the dust suppression treatment composition after being left standing for a long period of time, and also has excellent environmental performance.

The present invention provides a dust suppressant treatment composition for dust-producing substances, which comprises a non-melt-flowable aqueous dispersion of a TFE copolymer, wherein the redispersion sedimentation rate of a copolymer represented by the following formula (1) is 60% or less, the content of perfluorooctanoic acid and its salts in the aqueous dispersion is less than 10 ppb, the particle size (d84) of the copolymer is 50 to 250 nm when the cumulative volume percentage of the copolymer is 84%, and the particle size (d84) of the copolymer is 50 to 250 nm when the cumulative volume percentage of the copolymer is 84%, and the non-melt-flowable tetrafluoroethylene copolymer is a non-melt-flowable copolymer of tetrafluoroethylene and at least one comonomer selected from perfluoro(methyl vinyl ether), perfluoro(ethyl vinyl ether), (perfluoroalkyl)ethylene and hexafluoropropylene .

Redispersion sedimentation rate (%) = X ₃ /X ₂ ×100...(1)
During the ceremony,
_X2 : The solid sedimentation ratio (%) after redispersion, expressed by the following formula (2), is obtained by centrifuging 15 g of an aqueous dispersion of a TFE polymer having the same concentration as the copolymer at 20°C for 30 minutes at a rotation speed of 3,000 rpm in a centrifuge and then redispersing the dispersion.
_X3 : 15 g of the aqueous dispersion of the copolymer was mixed at a temperature of 20°C and a rotation speed of 300
The solid sedimentation rate (%) after redispersion is calculated by the following formula (2) when the solid is centrifuged at 0 rpm for 30 minutes using a centrifuge and then redispersed.
Percentage of solids settling after redispersion (%)
= (amount of settled solids after redispersion)/(amount of solids before centrifugation) × 100
... (2)

A preferred aspect of the present invention is that the perfluorooctanoic acid and its salts are present in an amount of less than 5 ppb relative to the mass of the aqueous dispersion.

A preferred embodiment of the present invention is that the perfluoroalkyl group in the (perfluoroalkyl)ethylene is a perfluoroalkyl group having 1 to 10 carbon atoms.

A preferred embodiment of the present invention is that the (perfluoroalkyl)ethylene is at least one selected from (perfluoroethyl)ethylene, (perfluorobutyl)ethylene, (perfluorohexyl)ethylene, and (perfluorooctyl)ethylene.

A preferred embodiment of the present invention is that the comonomer is contained in an amount of 0.01 to 1.00 mass% relative to TFE.

A preferred embodiment of the present invention is that the comonomer is contained in an amount of 0.01 to 0.50 mass% relative to TFE.

A preferred embodiment of the present invention is that the copolymer is contained in the dust suppression treatment composition at a concentration of 10 to 80% by mass.

It is a preferred aspect of the present invention that the specific gravity (SSG) of the copolymer is 2.27 or less.

The present invention also provides a dust suppression treatment powder for dust-generating substances, which is a powder obtained by granulating the dust suppression treatment composition and then drying it.

It is a preferred embodiment of the present invention that the dust-generating substance is a dust-generating powdery substance.

The present invention provides a dust suppression treatment composition for dust-generating substances that not only has excellent dust suppression properties for dust-generating substances, but also has excellent redispersibility of the non-melt-flowable TFE copolymer particles, which are the solid content in the dust suppression treatment composition, even after long-term storage, and is environmentally friendly.

FIG. 1 is a diagram showing the results of a centrifugal sedimentation test and a centrifugal sedimentation redispersion test for Examples 1 to 3 and Comparative Example 1. FIG. 1 is a diagram showing the results of a static sedimentation test and a static sedimentation redispersion test for Examples 1 and 2 and Comparative Example 1. Photographs of Example 2 and Comparative Example 1 after standing for 90 days.

The dust suppressant treatment composition for dust-generating substances of the present invention is a non-melt-flowable aqueous dispersion of a TFE copolymer, and has important features in that the redispersion sedimentation rate of the copolymer represented by the above formula (1) is 60% or less, and the content of perfluorooctanoic acid and its salts in the aqueous dispersion is less than 10 ppb.
By mixing the dust-suppressing treatment composition of the present invention with a dust-generating substance and subjecting the mixture to a compression-shear action at a temperature of about 20 to 200°C, the non-melt-flowable TFE copolymer can be fibrillated, thereby making it possible to suppress the generation of dust from the dust-generating substance.
As mentioned above, the TFE polymer particles, which are the solid content in the dust-suppressing treatment composition, are prone to settling, so when the aqueous dispersion of TFE polymer is left standing for a long period of time, the TFE polymer particles settle, and the settled TFE polymer particles solidify, making it difficult to redisperse by stirring etc. However, in the dust-suppressing treatment composition of the present invention, the redispersion settling rate of the non-melt-flowable TFE copolymer aqueous dispersion is 60% or less, so that the settled non-melt-flowable TFE copolymer particles are prevented from solidifying, and redispersibility can be significantly improved.As a result, a small amount of dust-suppressing treatment composition can be uniformly mixed with dust-generating material, so that the generation of dust from dust-generating material can be efficiently suppressed.In addition, the content of persistent perfluorooctanoic acid and its salt is less than 10 ppb, so that it is also excellent in environmental performance.

The excellent dust-suppressing performance and re-dispersibility of the dust suppression treatment composition of the present invention is evident from the results of the centrifugal sedimentation test, centrifugal re-dispersion test, static sedimentation test, static sedimentation re-dispersion test, and falling dust amount test in the examples described below.

(Redispersion Sedimentation Rate)
As is clear from Figure 1 showing the results of the centrifugal sedimentation test and the centrifugal sedimentation redispersion test, the dust-suppressing treatment composition of the present invention, in which the redispersion sedimentation rate of the non-melt-flowable TFE copolymer aqueous dispersion is 60% or less, has a reduced amount of sedimentation compared with the aqueous dispersion of TFE polymer in which the redispersion sedimentation rate exceeds 60%.
Furthermore, as shown in Examples 1 to 3 described later, it is clear that the dust-suppressing treatment composition of the present invention can be redispersed well when the redispersion sedimentation rate represented by the above formula (1) is 60% or less, preferably 50% or less, and more preferably 30% or less. Furthermore, the non-melt-flowable TFE copolymer of the present invention contains few rod-shaped particles that are prone to settling, and is therefore thought to have excellent sedimentation stability.

If the redispersion sedimentation rate represented by the above formula (1) exceeds 60%, the settled non-melt-flowable TFE copolymer particles solidify, making redispersion difficult. Furthermore, as a result of the settling of the solid non-melt-flowable TFE copolymer particles, the amount of non-melt-flowable TFE copolymer particles dispersed in the dust-suppressing treatment composition decreases, and in order to maintain the same dust-suppressing performance of dust-producing substances as before the settling, a larger amount of non-melt-flowable TFE copolymer aqueous dispersion is required. Furthermore, the solidified non-melt-flowable TFE copolymer cannot be used as a dust-suppressing treatment and must be discarded, which wastes much of the useful resource, the non-melt-flowable TFE copolymer, and also incurs disposal costs, making this undesirable from an economic standpoint.

(Non-melt flowable TFE copolymer)
The non-melt flowable TFE copolymer used in the present invention is preferably a non-melt flowable copolymer of tetrafluoroethylene (TFE) and at least one comonomer selected from perfluoro(alkyl vinyl ether), (perfluoroalkyl)ethylene, and hexafluoropropylene.

The (perfluoroalkyl)ethylene is preferably a (perfluoroalkyl)ethylene in which the perfluoroalkyl group has 1 to 10 carbon atoms, more preferably at least one selected from (perfluoroethyl)ethylene, (perfluorobutyl)ethylene, (perfluorohexyl)ethylene, and (perfluorooctyl)ethylene. Even more preferably, it is (perfluorobutyl)ethylene.

The perfluoro(alkyl vinyl ether) preferably has a perfluoroalkyl group having 1 to 10 carbon atoms, and more preferably at least one selected from perfluoro(methyl vinyl ether), perfluoro(ethyl vinyl ether), and perfluoro(propyl vinyl ether).

The comonomer in the non-melt-flowable TFE copolymer used in the present invention is contained in an amount of 0.01 to 1.00% by mass, preferably 0.01 to 0.50% by mass, and more preferably 0.01 to 0.30% by mass, relative to the TFE. When the comonomer content is 0.01 to 1.00% by mass, the stability of the aqueous dispersion is improved due to the small number of rod-shaped particles that tend to settle. On the other hand, when the comonomer content exceeds 1.00% by mass, the thermal stability decreases, which is undesirable. Furthermore, when the comonomer content is less than 0.01% by mass, the redispersion sedimentation rate is poor, which is undesirable.

The melting point of the non-melt-flowable TFE copolymer used in the present invention is 320 to 350° C., preferably 334 to 342° C. If the melting point is less than 320° C., the comonomer content in the non-melt-flowable copolymer increases, making it difficult to fibrillate, which is not preferred.
The non-melt-flowable TFE copolymer used in the present invention is preferably a copolymer that does not exhibit melt-moldability at temperatures above its melting point, and is preferably a copolymer whose MFR cannot be measured at temperatures above its melting point according to ASTM D1238 (372°C, load 5 kg).Such a non-melt-flowable TFE copolymer is different from the TFE copolymer that has melt-flowability and can be melt-formed.

The specific gravity (SSG) of the non-melt-flowable TFE copolymer is preferably 2.27 or less, preferably 2.22 or less, and more preferably 2.20 or less. The larger the SSG value, the smaller the molecular weight, and vice versa. Therefore, the smaller the SSG value, i.e., the higher the molecular weight, the easier it is to fibrillate with a small shear force, and when mixed with a dust-generating substance, fibrils are easily generated, resulting in a high dust-suppression effect. On the other hand, the larger the SSG value (greater than 2.27), i.e., the smaller the molecular weight, the more difficult it is to fibrillate, resulting in a poorer dust-suppression effect from dust-generating substances, which is undesirable.

The non-melt-flowable TFE copolymer aqueous dispersion of the present invention is an aqueous dispersion in which fine particles (colloidal particles) of a high-molecular-weight non-melt-flowable TFE copolymer are dispersed.
The colloidal particles in the non-melt-flowable TFE copolymer aqueous dispersion are preferably colloidal particles whose particle diameter (d84) at cumulative volume percentage of 84% is 250 nm or less, preferably 50-250 nm, more preferably 50-225 nm.If d84 is less than 50 nm, the effect of suppressing dust from dust-generating substances may be lower than when it is within the above range, while if d84 exceeds 250 nm, the sedimentation stability (dispersion stability) of colloidal particles is lowered, which is undesirable.
A particle size (d84) of 250 nm or less means that, unlike a particle size (d50) of 250 nm or less, there are no extremely large primary particles, and this means that the sedimentation stability of the aqueous dispersion is excellent.

In the present invention, the concentration of the non-melt-flowable TFE copolymer in the non-melt-flowable TFE copolymer aqueous dispersion is not particularly limited, but is in the range of 10 to 80 mass%, preferably 15 to 80 mass%, more preferably 20 to 80 mass%.
In order to enhance the dispersion effect of the non-melt-flowable TFE copolymer in dust-generating materials, the lower the concentration of the non-melt-flowable TFE copolymer, the better; if the concentration of the non-melt-flowable TFE copolymer is high, it is undesirable because it may impair sedimentation stability (dispersion stability).On the other hand, when transporting the non-melt-flowable TFE copolymer aqueous dispersion, the higher its concentration, the more transportation cost can be saved.Therefore, the concentration of the non-melt-flowable TFE copolymer in the dust suppression treatment composition of the present invention is preferably 10% by mass or more, particularly in the range of 20 to 80% by mass.
Furthermore, when mixing with a dust-generating substance, in order to enhance the dispersing effect of the non-melt-flowable TFE copolymer in the dust-suppressing treatment composition, the dust-suppressing treatment composition can be diluted with water so that the concentration of the non-melt-flowable TFE copolymer is 5 mass % or less.

In the present invention, the content of perfluorooctanoic acid and its salt in the non-melt-flowable TFE copolymer aqueous dispersion is preferably less than 10 ppb, preferably less than 5 ppb, more preferably 0 ppb, based on the mass of aqueous dispersion.Because perfluorooctanoic acid and its salt are difficult to decompose and have concern about environmental impact, it is desired that their content be as low as possible.
The concentration of perfluorooctanoic acid and its salts in the non-melt-flowable TFE copolymer aqueous dispersion can be calculated by freezing 10 ml of the non-melt-flowable TFE copolymer aqueous dispersion in a polyethylene container in a freezer at −20° C., flocculating the non-melt-flowable TFE copolymer and separating it from the water, transferring the entire contents of the polyethylene container to a Soxhlet extractor, extracting with about 80 ml of methanol for 7 hours, and measuring the diluted sample liquid by liquid chromatography.

There are no particular limitations on the method for preparing a non-melt-flowable aqueous dispersion of a TFE copolymer having a perfluorooctanoic acid and salts thereof content of less than 10 ppb, but the following method can be exemplified.
For example, as disclosed in the above-mentioned Patent Documents 3 and 4, there is a method in which perfluorooctanoic acid and its salts are not used as polymerization agents during polymerization, but an ammonium salt of a fluoromonoether acid (C ₃ F ₇ -0-CF(CF ₃ )COOH) and an ammonium salt of a fluoropolyether acid (C ₃ F ₇ -O-[CF(CF ₃ )CF ₂ ]n-CF(CF ₃ )COOH) are used to polymerize a TFE copolymer.

In the present invention, the non-melt-flowable TFE copolymer in the dust suppression treatment composition for dust-generating substances is a non-melt-flowable TFE copolymer of TFE and the above-mentioned comonomer, and has a redispersion sedimentation rate of 60% or less. This not only enables the copolymer to fibrillate in the same way as a TFE homopolymer, achieving dust suppression effects, but also enables an excellent redispersion sedimentation rate. Furthermore, the content of perfluorooctanoic acid and its salts in the non-melt-flowable TFE copolymer aqueous dispersion is less than 10 ppb, providing excellent environmental friendliness.

The non-melt-flowable TFE copolymer aqueous dispersion used in the present invention may further contain an emulsion stabilizer to enhance the stability of the non-melt-flowable TFE copolymer aqueous dispersion. A hydrocarbon-based anionic surfactant is preferred as the emulsion stabilizer. This surfactant essentially forms water-insoluble or poorly soluble salts with calcium, aluminum, and iron, which are soil components, thereby preventing surfactant-induced contamination of rivers, lakes, and groundwater.

Examples of such hydrocarbon-based anionic surfactants include higher fatty acid salts, higher alcohol sulfate salts, liquid fatty oil sulfate salts, fatty alcohol phosphate salts, dibasic fatty acid ester sulfonates, and alkyl aryl sulfonates. In particular, Na, K, Li, and NH4 salts of polyoxyethylene alkyl phenyl ether ethylene sulfonates (polyoxyethylene n is 1 to 6, alkyl has 8 to 11 carbon atoms), alkyl benzene sulfonates (alkyl has 10 to 12 carbon atoms), dialkyl sulfosuccinates (alkyl has 8 to ₁₀ carbon atoms), etc. can be exemplified as preferred because they can impart high mechanical stability to non-melt-flowable TFE copolymer aqueous dispersions and prevent aggregation of non-melt-flowable TFE copolymer particles due to high-speed stirring, etc.

(Dust suppression treatment method)
The dust-suppressing treatment method using the dust-suppressing treatment composition of the present invention comprises mixing the dust-suppressing treatment composition of the present invention with a dust-generating substance, subjecting the mixture to a compression-shear action at a temperature of 20 to 200°C, preferably 50 to 150°C, to fibrillate the non-melt-flowable TFE copolymer in the composition, thereby making it possible to suppress the generation of dust from the dust-generating substance.
That is, the specific non-melt-flowable TFE copolymer used in the present invention is fibrillated into spider web-like ultrafine fibers when subjected to compression-shear action under the appropriate conditions as described above, and therefore, it is thought that in the dust-suppressed treated product treated with the dust-suppressing treatment composition of the present invention, dust-generating substances are captured and agglomerated in the spider web-like fine fibers, thereby suppressing dust.

The dust-producing substances to be treated with the dust-suppressing treatment composition of the present invention are inorganic and/or organic dust-producing substances, and there are no particular limitations on the substance or shape. The dust-suppressing treatment composition of the present invention can also be effectively applied to dust-producing powdery substances. Particularly suitable dust-producing substances that can be treated include cements such as Portland cement and alumina cement; slaked lime, quicklime powder, calcium carbonate, mineral powders such as dolomite, magnesite, talc, silica stone, and fluorite; clay mineral powders such as kaolin and bentonite; slag powders by-produced in the production of metals and non-ferrous metals such as iron and steel; combustion ash powders such as coal and garbage; gypsum powder; powdered metals; carbon black, activated carbon powder; ceramic powders such as metal oxides; and pigments. In other words, these are all dust-producing substances that disperse and float in the air as solid particulate matter, generating dust.

The amount of the dust-suppressing treatment composition of the present invention to be added to a dust-generating substance can be appropriately determined depending on the type of dust-generating substance, particle size distribution, specific gravity (true specific gravity, apparent specific gravity), dust-suppressing treatment temperature, the degree of compression-shear action applied, the degree of dust suppression of the resulting dust-suppressing treated product, and the like.
As a guideline for the amount to be added, for example, the dust-suppressing treatment composition can be added in an amount of 0.001 to 1.0 mass %, preferably 0.005 to 0.50 mass %, calculated as the solid content of the non-melt-flowable TFE copolymer resin, relative to the dust-generating powdery substance, to suppress dust generated from the dust-generating powdery substance.

Furthermore, the dust suppression treatment composition for dust-generating substances of the present invention does not solidify the non-melt-flowable TFE copolymer even after long-term storage, meaning that it has excellent redispersibility (low redispersion sedimentation rate), which makes it possible to reduce disposal costs and is therefore also preferable from an economic standpoint.

Furthermore, by using a dust-suppression treatment powder for dust-generating substances, which is obtained by granulating the dust-suppression treatment composition for dust-generating substances of the present invention and then drying it, it is possible to perform dust-prevention treatment on dust-generating substances that are hygroscopic or deliquescent and dislike moisture. For information on dust-prevention treatment methods using powder, see, for example, Japanese Patent Publication No. 52-32877.

The present invention will be described in more detail below with reference to examples and comparative examples, but the present invention is not limited to these examples. Examples 11 to 13 and Examples 32 to 35 are reference examples.
In the present invention, the physical properties were measured by the following methods.

[1] Particle size at cumulative volume percentage 84% (d84)
The particle size (d84) of non-melt-flowable TFE copolymer particles or the particle size of TFE polymer particles was measured using a Microtrac UPA150 Model No. 9340 (manufactured by Nikkiso Co., Ltd.).

[2] Standard specific gravity (SSG)
Measured according to ASTM D-4894.
A non-melt-flowable aqueous TFE copolymer dispersion or TFE polymer dispersion obtained by emulsion polymerization was adjusted to a concentration of 15% by mass using pure water. Approximately 750 ml of the non-melt-flowable aqueous TFE copolymer dispersion or TFE polymer dispersion adjusted to the above concentration was then placed in a polyethylene container (500 ml capacity) and vigorously shaken by hand to aggregate and separate the solids. The separated solids were dried at 150°C for 2 hours. 12.0 g of the dried solids (resin powder) were placed in a cylindrical mold with a diameter of 2.85 cm and flattened. The pressure was gradually increased until a final pressure of 350 kg/ ^cm2 was reached after 30 seconds, and the final pressure of 350 kg/ ^cm2 was maintained for 2 minutes. The preforms thus obtained (two for each sample) were heated in an air oven from 290°C to 380°C at 2°C/min, held at 380°C for 30 minutes, cooled to 294°C at 1°C/min, held at 294°C for 1 minute, removed from the oven, and cooled to room temperature (23±1°C) to prepare a standard sample. The mass ratio of the standard sample to the mass of the same volume of water at room temperature (23±1°C) was used as the standard gravity. In this case, the average of the standard gravities of the two samples was calculated and used as the standard gravity.
This standard specific gravity serves as a guide for the average molecular weight, and generally the lower the standard specific gravity, the higher the molecular weight.

[3-1] Comonomer content (perfluorobutylethylene (PFBE) content)
In the same manner as in the above [2], 0.8±0.050g of the dried solid matter (resin powder) obtained from the non-melt-flowable TFE copolymer aqueous dispersion or TFE polymer aqueous dispersion is placed in a cylindrical mold with a diameter of 2.85cm, smoothed between aluminum foils, and gradually increased pressure until the final pressure reaches 496kg/ ^cm2 after 30 seconds, and maintained this final pressure for 2 minutes to obtain a sample for measurement.Similarly, measurement samples are also prepared for resin powders with known PFBE content (mass%) (two points with PFBE content of 0 mass% and 0.03 mass%).The infrared spectrum of these samples is measured, and the absorbance ratio X is calculated according to the following formula (3).
Absorbance ratio X=(CB)/(AB)...(3)
A: 936 ^cm peak height (absorbance)
B: 887 ^cm peak height (absorbance)
C: 875 cm ⁻¹ peak height (absorbance)
A calibration curve was created from the PFBE contents (mass%) and absorbance ratio X of two samples with known PFBE contents (mass%), and the PFBE contents (mass%) of the samples were calculated from the absorbance ratio X of the samples.

[3-2] Comonomer content (perfluoropropyl vinyl ether (PPVE) content)
Using the same method as in [2] above, 1.75±0.005 g of a non-melt-flowable aqueous TFE copolymer dispersion or a dried solid (resin powder) obtained from an aqueous TFE polymer dispersion was placed in a cylindrical mold with a diameter of 2.85 cm, smoothed between aluminum foil, and pressure was applied for 30 seconds, gradually increasing until a final pressure of 1470 kg/ ^cm2 was reached. This final pressure was maintained for 2 minutes, yielding measurement sample 1. Similarly, measurement samples were also prepared for resin powders with known PPVE contents (mass%) (two points with PPVE contents of 0 mass% and 0.75 mass%). The infrared spectra of these samples were measured, and the absorbance ratio and absorbance ratio _X1 were calculated using the following equations (4) and (5).
Absorbance ratio X ₁ = (absorbance ratio of sample 1/absorbance ratio of known resin powder)×
0.75 (4)
Absorbance ratio = B ₁ /A ₁ (5)
A ₁ : 936 cm ⁻¹ peak height (absorbance)
B ₁ : 994 cm ⁻¹ peak height (absorbance)
A calibration curve was created from the PPVE contents (mass%) and absorbance ratio _X1 of two samples with known PPVE contents (mass%), and the PPVE content (mass%) of the sample was determined from the absorbance ratio _X1 of the sample.

[3-3] Comonomer content (hexafluoropropylene (HFP) content)
Using the same method as in [2] above, 1.75±0.005 g of a sample of the dried solid (resin powder) obtained from a non-melt-flowable TFE copolymer aqueous dispersion or a TFE polymer aqueous dispersion was placed in a cylindrical mold with a diameter of 2.85 cm and smoothed between aluminum foils. Pressure was applied for 30 seconds, gradually increasing until the final pressure reached 1470 kg/cm ² , and this final pressure was maintained for 2 minutes to obtain a sample for measurement. Similarly, measurement samples were also prepared for resin powders with known HFP contents (mass%) (three HFP contents of 0.06 mass%, 0.08 mass%, and 0.12 mass%). The infrared spectra of these samples were measured, and the absorbance ratio and absorbance ratio _X2 were calculated using the following formulas (6) and (7).
Absorbance ratio X ₂ = (absorbance ratio of sample/absorbance ratio of known sample) × 0.42
...(6)
Absorbance ratio = B ₂ /A ₂ (7)
A ₂ : 936 cm ⁻¹ peak height (absorbance)
B ₂ : 983 cm ⁻¹ peak height (absorbance)
A calibration curve was created from the HFP contents (% by mass) and absorbance ratio _X2 of three samples with known HFP contents (% by mass), and the HFP contents (% by mass) of the samples were calculated from the absorbance ratio _X2 of the samples.

[4] Solid content mass%
Less than 6g of non-melt flowable TFE copolymer aqueous dispersion or TFE polymer aqueous dispersion is measured and placed in a weighed aluminum dish, and the mass (mass before drying) of non-melt flowable TFE copolymer aqueous dispersion or TFE polymer aqueous dispersion is measured (measured to four decimal places).Then, it is left standing in a 105 ℃ dryer for 2 hours to remove moisture, baked in a constant temperature oven at 380 ℃ for 20 minutes, cooled to room temperature, and then its mass (mass after drying) is measured, and the solid content mass% is calculated by the following formula (8):
Solid content mass% = [(mass after drying - tare mass of aluminum dish) / mass before drying] x
100...(8)

[5] Melting point: In the same manner as in [2] above, 10.0±0.3 mg of a non-melt-flowable TFE copolymer aqueous dispersion or a dried solid (resin powder) obtained from a TFE polymer aqueous dispersion was placed in a measurement Super Clean aluminum sample pan (manufactured by PerkinElmer Japan Co., Ltd.), and then a cover was placed on it, and a measurement sample was prepared by sealing it using a standard crimper press. The measurement sample was measured using a power compensation differential scanning calorimeter Diamond DSC (manufactured by PerkinElmer Japan Co., Ltd.), and an empty Super Clean aluminum sample pan was used as the reference material, and the calorific value was measured while heating from 200 ° C. to 370 ° C. at a rate of 10 ° C. per minute. As a result of the measurement, the temperature at the point where the observed endothermic peak was at its maximum was taken as the melting point of the measurement sample (resin powder).

[6] Centrifugal Sedimentation Test 15 g of a non-melt-flowable aqueous TFE copolymer dispersion or aqueous TFE polymer dispersion having the composition shown in Table 1 was placed in a centrifuge tube (15 ml centrifuge tube, manufactured by Corning Co., Ltd.), and centrifuged for 30 minutes at 20°C and 3,000 rpm using a centrifuge (Tabletop Refrigerated Centrifuge 5500, Angle Rotor RA508, manufactured by Kubota Corporation). After centrifugation, everything except the solids that had settled to the bottom of the centrifuge tube (liquid portion: supernatant and unsettled solids) was removed from the centrifuge tube, and the centrifuge tube was left in an inverted position for 30 minutes, after which the liquid portion was further removed. The mass (the sum of the mass of the centrifuge tube and the mass of the solids that had settled to the bottom of the centrifuge tube) was measured, and the mass obtained by subtracting the mass of the centrifuge tube from this was used as the amount of solids that had settled. The solids settling ratio was calculated from the following formula (10), and the sedimentation rate was calculated from the following formula (9).

Sedimentation rate = X ₁ / X ₀ × 100 (9)
During the ceremony,
_X0 : The solid sedimentation rate (%), as shown by the following formula (10), when 15 g of the aqueous TFE polymer dispersion shown in Comparative Example 1 is centrifuged at a temperature of 20°C and a rotation speed of 3,000 rpm for 30 minutes in a centrifuge, and then the solids other than those sedimented at the bottom of the centrifuge tube (liquid portion: supernatant and unsettled solids) are removed.
X ₁ : 15 g of a non-melt-flowable aqueous dispersion of a TFE copolymer shown in the examples
After centrifugation at 20°C and 3000 rpm for 30 minutes, the solid matter other than the solid matter that settled at the bottom of the centrifuge tube (liquid portion:
The following formula (10) is obtained when the supernatant and unsettled solids are removed.
The solid sedimentation rate (%) is shown as
= (amount of settled solids) / (mass of solids before centrifugation) × 100 (10)

[7] Centrifugal Redispersion Test The mass of the centrifuge tube from which the liquid portion was removed in [6] above was measured, 10 g of pure water was added to the centrifuge tube, and the solids that had settled to the bottom of the centrifuge tube were ultrasonically dispersed at 38 kHz for 1 minute. After that, all solids other than those that had settled to the bottom of the centrifuge tube (the liquid portion and the redispersed solids) were removed, and the centrifuge tube was left in an inverted position for 30 minutes to further remove the liquid portion. The weight (the sum of the mass of the centrifuge tube and the mass of the solids that had settled to the bottom of the centrifuge tube) was measured, and the mass obtained by subtracting the mass of the centrifuge tube from this was used as the amount of solids that had settled after redispersion. The solids settling ratio after redispersion was calculated from the following formula (2 '), and the redispersion sedimentation rate was calculated from the following formula (1 ').

Redispersion sedimentation rate (%) = X ₃ /X ₂ ×100...(1')
During the ceremony,
X ₂ : 15 g of the aqueous dispersion of the TFE polymer shown in Comparative Example 1 was heated at a temperature of 20° C.
The solid sedimentation rate (%) is calculated by the following formula (2') when the mixture is centrifuged at a rotation speed of 3000 rpm for 30 minutes and then redispersed.
X ₃ : 15 g of a non-melt-flowable aqueous dispersion of the TFE copolymer shown in the examples
The solid sedimentation rate (%) is calculated by the following formula (2') when the mixture is centrifuged at 20°C and 3000 rpm for 30 minutes and then redispersed.
Percentage of solids settling after redispersion (%)
= (amount of settled solids after redispersion)/(mass of solids before centrifugation)×100
...(2')

[8] Static Sedimentation Test As shown in Table 2, 15 g of non-melt-flowable TFE copolymer aqueous dispersion or TFE polymer aqueous dispersion was placed in a centrifuge tube, and after closing the opening of the centrifuge tube, it was left standing at room temperature for 30 days, 60 days, and 90 days, respectively. After leaving it standing for 30 days, 60 days, and 90 days, the opening of the centrifuge tube was opened, and the liquid portion other than the settled solids (liquid portion: supernatant and unsettled solids) was removed, and the centrifuge tube was left standing in an upside-down state for 30 minutes, and the liquid portion was further removed, and its mass (the sum of the mass of the centrifuge tube and the mass of the solids settled at the bottom of the centrifuge tube) was measured, and the mass obtained by subtracting the mass of the centrifuge tube from this was taken as the amount of settled solids after leaving it standing, and the solid sedimentation rate was calculated from the following formula (12) and the sedimentation rate from the following formula (11).

Sedimentation rate = X ₅ / X ₄ × 100 (11)
During the ceremony,
_X4 : The solid sedimentation ratio (% ) of 15 g of the aqueous TFE polymer dispersion shown in Comparative Example 1 was measured by closing the opening of the centrifuge tube and leaving it to stand at room temperature for 30 days, 60 days, and 90 days, respectively, and then removing all but the settled solids (liquid portion: supernatant and non-settled solids), inverting the centrifuge tube and leaving it to stand for 30 minutes, and then further removing the liquid portion, as shown by the following formula (12):
)
X ₅ : 15 g of a non-melt-flowable aqueous dispersion of the TFE copolymer shown in the examples
After closing the centrifuge tube, leave it at room temperature for 30 days, 60 days, and 90 days, and then remove all solids except for the settled solids (liquid portion: supernatant and unsettled solids). Then, leave the centrifuge tube upside down for 30 minutes, remove the liquid portion, and measure the amount of settled solids (mass) after leaving it.
The solid sedimentation rate (%) is calculated using the following formula (12):
Solid sedimentation rate (%)
= (amount of solids settling after standing)/(mass of solids before standing)×100
...(12)

[9] Static Sedimentation and Redispersion Test The mass of the test tube left to stand in [8] above was measured, 10 g of pure water was added to the centrifuge tube, and the solid content that had settled to the bottom of the centrifuge tube was ultrasonically dispersed at 38 kHz for 1 minute. After that, all the solid content other than the solid content that had settled to the bottom of the centrifuge tube (the liquid portion and the redispersed solid content) was removed, and the centrifuge tube was left to stand in an inverted position for 30 minutes, and the liquid portion was further removed. The mass (the sum of the mass of the centrifuge tube and the amount of solid content that had settled to the bottom of the centrifuge tube) was measured, and the mass obtained by subtracting the mass of the centrifuge tube from this was used as the amount of solid content that had settled after redispersion. The redispersed solid content sedimentation ratio was calculated from the following formula (14), and the redispersion sedimentation rate was calculated from the following formula (13).

Redispersion sedimentation rate=X ₇ /X ₆ ×100...(13)
During the ceremony,
_X6 : The solid sedimentation ratio (%), as shown by the following formula (14), is obtained when 15 g of the aqueous TFE polymer dispersion shown in Comparative Example 1 is allowed to stand at room temperature for 30 days, 60 days, and 90 days after closing the centrifuge tube, and then everything except the settled solids (liquid portion: supernatant and non-settled solids) is removed, the centrifuge tube is left to stand in an upside-down position for 30 minutes, the liquid portion is further removed, and the dispersion is redispersed.
_X7 : 15 g of a non-melt-flowable aqueous dispersion of a TFE copolymer shown in the examples
After closing the centrifuge tube, the tube was left standing at room temperature for 30 days, 60 days, and 90 days, and then all the solid matter other than the settled solid matter (liquid part: supernatant and unsettled solid matter) was removed. The tube was then left standing upside down for 30 minutes, and the liquid part was further removed. After re-dispersion, the following formula (14) was obtained.
) is the solid sedimentation percentage (%).
Percentage of solids settling after redispersion (%)
= (amount of settled solids after redispersion)/(mass of solids before centrifugation)×100
...(14)

[10] Falling dust test (amount of falling dust)
200 g of a sample (dust-suppressing treated product) was allowed to fall naturally from the top opening of a cylindrical container with an inner diameter of 39 cm and a height of 59 cm, and the amount of suspended dust (relative concentration (CPM: Counts per Minute)) in the container at a position 45 cm above the bottom was measured using a scattered light digital dust meter.
The amount of suspended dust was measured five times consecutively for one minute after the sample was added, and the geometric mean value x (CPM) obtained by subtracting the value measured before the sample was added (dark count) was used as the "amount of fallen dust" for the sample. The geometric mean value x was calculated using the following formula (15):
Log x=(1/5)×Σlog(xi-d)...(15)
In the formula, xi: amount of individual suspended dust particles, and d: dark count.
If the falling dust amount (CPM) is 50 or less, the dust prevention performance is more excellent, which is more preferable.

Example 1
(Polymerization of non-melt flowable TFE copolymer)
A 4-liter stainless steel (SUS316) autoclave equipped with a stirring blade and a temperature-controlling jacket was charged with 60 g of paraffin wax, 2087 ml of deionized water, 12.03 g of the ammonium salt of fluoromonoether acid (formula: C ₃ F ₇ -O-CF(CF ₃ )COOH), 1.0 g of the ammonium salt of fluoropolyether acid (C ₃ F ₇ -O-[CF(CF ₃ )CF ₂ ]n-CF(CF ₃ )COOH), and 0.01 g of polyoxyethylene alkylphenyl ether. The system was purged with nitrogen gas three times while heated to 80°C to remove oxygen, and then evacuated. Thereafter, 4.4 g of PFBE, 0.2 g of ammonium salt of fluoromonoether acid, and 199.8 ml of deionized water were charged, and then tetrafluoroethylene (TFE) was supplied to adjust the internal pressure to 1.90-1.98 MPa. The internal temperature was maintained at 80°C while stirring at 110 rpm.

Next, 100 ml of an aqueous solution prepared by dissolving 0.12 g of ammonium persulfate in 400 ml of water was pumped into the autoclave. After the injection of the ammonium persulfate aqueous solution was completed, TFE was continued to be supplied to maintain the internal pressure at 2.0 MPa. When 1,106.79 g of TFE had been consumed, stirring was stopped. The gas inside the autoclave was released to atmospheric pressure, and the autoclave was evacuated. After returning the pressure to atmospheric pressure with nitrogen gas, the contents were removed and the reaction was terminated, yielding a non-melt-flowable aqueous dispersion of TFE copolymer.

The resulting non-melt-flowable TFE copolymer aqueous dispersion was measured for particle size at a cumulative volume percentage of 84% (d84), SSG, PFBE content, solids mass, melting point, and the amount of perfluorooctanoic acid and its salts. A centrifugal sedimentation test and a centrifugal sedimentation redispersion test were also conducted. The results are shown in Table 1 and Figure 1.

Examples 2 and 3
A non-melt-flowable TFE copolymer aqueous dispersion was obtained in the same manner as in Example 1, except that the amount of PFBE was changed to the amount shown in Table 1. The particle size (d84) at a cumulative volume percentage of 84%, SSG, PFBE content, solid mass, melting point, and amount of perfluorooctanoic acid and its salts were measured for the obtained non-melt-flowable TFE copolymer aqueous dispersion. In addition, a centrifugal sedimentation test and a centrifugal sedimentation redispersion test were also carried out. The results are shown in Table 1 and Figure 1.

(Comparative Example 1)
For an aqueous TFE polymer dispersion (Teflon (registered trademark) PTFE Dispersion 312-JR, manufactured by Mitsui-Chemours Fluoroproducts Co., Ltd.), the particle size (d84) at a cumulative volume percentage of 84%, SSG, PFBE content, solid mass, and the amount of perfluorooctanoic acid and its salts were measured. In addition, a centrifugal sedimentation test and a centrifugal sedimentation redispersion test were conducted. Furthermore, physical property analysis was carried out in the same manner as in Example 1. The results are shown in Table 1 and FIG. 1.

Furthermore, a static settling test and a static settling redispersion test were conducted for Examples 1 and 2 and Comparative Example 1. The results are shown in Table 2 and Figure 2. Figure 3 also shows photographs of Example 2 and Comparative Example 1 after 90 days of static setting.

(Dust-falling test)
(Example 4, Comparative Example 2)
1,000 g of powdered quicklime containing 95.7% CaO and 1.6% MgO (powdered quicklime that passed through a 2.0 mm standard mesh sieve, 17.3% on a 1.0 mm standard mesh sieve, 18.9% on a 600 μm standard mesh sieve, 18.1% on a 300 μm standard mesh sieve, 14.1% on a 150 μm standard mesh sieve, and 31.6% passing through a 150 μm standard mesh sieve) was placed in a small soil mixer with a volume of 5 liters and stirred at a rotation speed of 140 rpm. Alternatively, the non-melt-flowable aqueous TFE copolymer dispersion or aqueous TFE polymer dispersion prepared in Comparative Example 1 was weighed out in an amount equivalent to 0.05 g in terms of solid content (0.005% by mass in terms of the solid content of the non-melt-flowable TFE copolymer or TFE polymer relative to the quicklime), diluted with water so that the total amount of water and moisture contained in the non-melt-flowable aqueous TFE copolymer dispersion or aqueous TFE polymer dispersion became 100 g, and the resulting dispersion was gradually added.
Approximately one minute after the start of addition, steam began to be generated due to the heat of the quicklime hydration reaction, and approximately two minutes later, all of the water was used up to produce slaked lime through the hydration of the quicklime, and steam generation ceased. Three minutes after the start of stirring, the mixer's stirring was stopped. The temperature at this time was measured with a thermometer and was 107°C. This dust-suppressed treated quicklime was a mixture of quicklime and slaked lime, with approximately 30% slaked lime newly produced by the hydration reaction. A drop dust generation test was conducted on the resulting dust-suppressed treated product. The results are shown in Table 3.

(Examples 5 and 6, Comparative Examples 3 and 4)
The non-melt-flowable aqueous TFE copolymer dispersion or aqueous TFE polymer dispersion prepared in Example 2 or Comparative Example 1 was weighed out in an amount corresponding to the addition amount shown in Table 3 (solids mass % relative to the dust-generating substance), and the non-melt-flowable aqueous TFE copolymer dispersion or aqueous TFE polymer dispersion was diluted with water so that the total amount of water and moisture contained in the aqueous TFE copolymer dispersion or TFE polymer dispersion was 100 g. Except for this, a dust-suppressed treated mixture of quicklime and slaked lime was obtained in the same manner as in Example 4. The resulting dust-suppressed treated product was subjected to a drop dust generation test. The results are shown in Table 3.

(Comparative Example 5)
A drop dust test was carried out on a mixture of quicklime and slaked lime obtained in the same manner as in Example 4, except that 100 g of water was used instead of the non-melt-flowable TFE copolymer aqueous dispersion or TFE polymer aqueous dispersion. The results are shown in Table 3.

(Examples 7 to 13)
(Polymerization of non-melt flowable TFE copolymer)
A 4-liter stainless steel (SUS316) autoclave equipped with a stirring blade and a temperature-controlling jacket was charged with 60 g of paraffin wax, 2087 ml of deionized water, 12.03 g of the ammonium salt of _{fluoromonoether} acid (formula: _C3F7-0 -CF( _CF3 )COOH), 1.0 g of the ammonium salt of _{fluoropolyether acid (C3F7-0- [} CF( _CF3 ) _CF2 ]n-CF( _CF3 )COOH), and 0.01 g of polyoxyethylene alkylphenyl ether. The system was purged with nitrogen gas three times while heating to 80°C to remove oxygen, and then evacuated. Thereafter, the comonomer (HFP or PPVE) was pumped in the amount shown in Table 4. Thereafter, tetrafluoroethylene (TFE) was supplied to adjust the internal pressure to 1.90-1.98 MPa, and the internal temperature was maintained at 80°C while stirring at 110 rpm.

Next, 100 ml of an aqueous solution prepared by dissolving 0.12 g of ammonium persulfate in 400 ml of water was pumped into the autoclave. After the injection of the ammonium persulfate aqueous solution was completed, TFE was continued to be supplied to maintain the internal pressure at 2.0 MPa. When 1,106.79 g of TFE had been consumed, stirring was stopped. The gas inside the autoclave was released to atmospheric pressure, and the autoclave was evacuated. After returning the pressure to atmospheric pressure with nitrogen gas, the contents were removed and the reaction was terminated, yielding a non-melt-flowable aqueous dispersion of TFE copolymer.

The resulting non-melt-flowable TFE copolymer aqueous dispersion was measured for particle size at a cumulative volume percentage of 84% (d84), SSG, PFBE content, solids mass, melting point, and the amount of perfluorooctanoic acid and its salts. A centrifugal sedimentation test and a centrifugal sedimentation redispersion test were also conducted. The results are shown in Table 4.

(Examples 14, 15, 21, 23, 24, 29, 30, 32 to 35)
The dust-generating substance shown below and the non-melt-flowable TFE copolymer aqueous dispersions prepared in Examples 7 to 13 were weighed out in amounts corresponding to the addition amounts (% by mass of solids relative to the dust-generating substance) shown in Table 5 or Table 6, and the dispersions were diluted with water so that the total amount of water and moisture contained in the non-melt-flowable TFE copolymer aqueous dispersion was 100 g. Dust-suppressing treated products were obtained by the following method. The resulting dust-suppressing treated products were subjected to a drop dust generation test. The results are shown in Table 5 or Table 6.

(Examples 16 to 20, 22, 25 to 28, and 31)
The dust-producing substance shown below and the non-melt-flowable TFE copolymer aqueous dispersions prepared in Examples 7 to 13 were weighed out in amounts corresponding to the addition amounts (% by mass of solids relative to the dust-producing substance) shown in Table 5 or Table 6, and the dispersions were diluted with water so that the total amount of water and moisture contained in the non-melt-flowable TFE copolymer aqueous dispersion was 35 g. Dust-suppressing treated products were obtained by the following method. The resulting dust-suppressing treated products were subjected to a drop dust generation test. The results are shown in Table 5 or Table 6.

<Dusting substances>
Powdered quicklime (containing 96.0% CaO and 0.9% MgO)
(Powdered quicklime that passed through a 2.0 mm standard mesh sieve in its entirety, retained 0.18% on a 1.0 mm standard mesh sieve, retained 2.48% on a 600 μm standard mesh sieve, retained 20.44% on a 300 μm standard mesh sieve, retained 20.58% on a 150 μm standard mesh sieve, and passed 56.32% on a 150 μm standard mesh sieve)
Dustproof treatment of powdered quicklime (Examples 14, 15, 21, 23, 24, 29, 30, 32 to 35):
1000 g of powdered quicklime was weighed into a mortar mixer container, the container was set in the mortar mixer and stirred at a low speed, the water-diluted dispersion (the mass of the non-melt-flowable TFE copolymer corresponding to the addition amount shown in Table 5 + 100 g of water) was charged into the mortar mixer, and stirring of the mixer was stopped 3 minutes after the start of stirring. Thereafter, the quicklime in the mortar mixer was transferred to an enamel tray and allowed to cool for about 5 minutes to obtain a dust-suppressing treated product.

Ordinary Portland cement (containing 64.3% CaO, 1.1% MgO, 20.5% SiO ₂ , 5.1% Al ₂ O ₃ , 3.1% Fe ₂ O ₃ and 2.0% SO ₃ )
(Ordinary Portland cement that passed through a 2.0 mm standard mesh sieve, a 1.0 mm standard mesh sieve, a 600 μm standard mesh sieve, a 300 μm standard mesh sieve, 0.22% remaining on a 150 μm standard mesh sieve, and 99.78% passing through a 150 μm standard mesh sieve)
Dustproof treatment of a 9:1 mixture of ordinary Portland cement (hereinafter referred to as cement) and the powdered quicklime (Examples 16, 22, 25, and 31):
Two 450g portions of cement were weighed out, spread evenly on an enamel tray, and heated at 105°C for one day and night. 100g of powdered quicklime was weighed into a mortar mixer container, and the water-diluted dispersion (the mass of the non-melt-flowable TFE copolymer corresponding to the amount added shown in Table 5 or Table 6 + 35g of water) was added to the mortar mixer and stirred at low speed for 1 minute to obtain material A. 450g of cement heated to 105°C was added to the obtained material A, and the mixture was further stirred for 1 minute to obtain material B. 450g of cement heated to 105°C was added to the obtained material B, and the mixture was stirred for 3 minutes in the mortar mixer to obtain a dust-suppressing treated product.

Anhydrous gypsum (anhydrous gypsum that passed completely through a 2.0 mm standard mesh sieve, completely through a 1.0 mm standard mesh sieve, 0.13% retained on a 600 μm standard mesh sieve, 0.22% retained on a 300 μm standard mesh sieve, 11.33% retained on a 150 μm standard mesh sieve, and 88.31% passed through a 150 μm standard mesh sieve)
Dustproof treatment of anhydrous gypsum (Examples 17 and 26):
500 g × 2 of anhydrous gypsum was weighed, spread evenly on an enamel tray, and heated for 24 hours at 105 ° C. 500 g of the heated anhydrous gypsum was weighed into the container of a mortar mixer, and the above-mentioned water-diluted dispersion (the mass of the non-melt-flowable TFE copolymer corresponding to the addition amount shown in Table 5 or Table 6 + 35 g of water) was added to the mortar mixer and stirred at low speed for 1 minute, and 500 g of anhydrous gypsum heated to 105 ° C was added and stirred for 3 minutes, and then the mixture was spread evenly on an enamel tray and heated at 105 ° C. for 1 hour to obtain a mixture. Approximately 1 kg of the mixture was placed in a mortar and stirred with a pestle for 9 minutes to obtain a dust-suppressing treated product.

Granulated blast furnace slag powder (granulated blast furnace slag that passed completely through a 2.0 mm standard mesh sieve, completely through a 1.0 mm standard mesh sieve, 0.02% remaining on a 600 μm standard mesh sieve, 0.06% remaining on a 300 μm standard mesh sieve, 0.31% remaining on a 150 μm standard mesh sieve, and 99.61% passing through a 150 μm standard mesh sieve)
Dust prevention treatment of granulated blast furnace slag powder (Examples 18 and 27):
A dust-suppressed treated product was obtained in the same manner as in the dust-prevention treatment of anhydrous gypsum, except that ground granulated blast furnace slag was used.

Dolomite (dolomite that passed through a 2.0 mm standard mesh sieve in its entirety, 0.06% on a 1.0 mm standard mesh sieve, 0.50% on a 600 μm standard mesh sieve, 3.44% on a 300 μm standard mesh sieve, 8.20% on a 150 μm standard mesh sieve, and 87.79% passed through a 150 μm standard mesh sieve)
Dust-proofing of dolomite (Examples 19 and 28):
Two 500g portions of dolomite were weighed, spread evenly on an enamel tray, and heated overnight at 105°C. 500g of the heated dolomite was weighed into a mortar mixer container, and the water-diluted dispersion (the mass of the non-melt-flowable TFE copolymer corresponding to the amount added shown in Table 5 or Table 6 + 35g of water) was added to the mortar mixer and stirred at low speed for 1 minute. 500g of dolomite heated to 105°C was added and stirred for 3 minutes, after which the mixture was spread evenly on an enamel tray and heated at 105°C for 1 hour to obtain a mixture. Approximately 1kg of the mixture was added to the mortar mixer and stirred for 3 minutes to obtain a dust-suppressing treated product.

Lignite powder (lignite powder that passed completely through a 2.0 mm standard mesh sieve, completely through a 1.0 mm standard mesh sieve, completely through a 600 μm standard mesh sieve, 0.02% retained on a 300 μm standard mesh sieve, 33.03% retained on a 150 μm standard mesh sieve, and 66.95% passed through a 150 μm standard mesh sieve)
Dust-proofing of lignite powder (Example 20):
500 g of lignite powder (a hygroscopic, dust-generating powder) was weighed out, spread evenly on an enamel tray, and heated overnight at 105°C. Pure water was added to the aqueous dispersion of Example 7 so that the solids content was 15%. The mixture was then placed in a granulation tank equipped with a stirrer and stirred at 600-700 rpm until a powder precipitated. After precipitation, stirring was continued for an additional 3-5 minutes. The precipitated powder was collected through a mesh and separated from the water. It was then dried in an oven at 150°C for 2-15 hours until the water content was completely gone, and then allowed to cool to room temperature, yielding a powder consisting of the aqueous dispersion of Example 7. 5 g of the resulting powder and approximately 1/4 of the heated lignite powder were placed in a mortar and slowly mixed with a pestle. The lignite powder was then added in three separate additions, and the mixture was then spread evenly on an enamel tray and heated at 105°C for 1 hour to obtain a mixture. About 500 g of the mixture was placed in a mortar and mixed with a pestle until the non-melt-flowable TFE copolymer was sufficiently fibrillated, to obtain a dust-suppressing treated material.

The dust-suppressing treatment composition of the present invention is suitable for use in dust-suppressing treatment of dust-generating substances to obtain dust-suppressing treated products in the fields of building materials, soil stabilization materials, solidification materials, fertilizers, landfill disposal of incineration ash or hazardous substances, explosion prevention, cosmetics, and fillers for various plastics.

Claims (10)

A dust-suppressing treatment composition for dust-generating substances, comprising an aqueous dispersion of a non-melt-flowable tetrafluoroethylene copolymer, wherein the copolymer represented by the following formula has a redispersion sedimentation rate of 60% or less, the content of perfluorooctanoic acid and salts thereof in the aqueous dispersion is less than 10 ppb, the particle size (d84) of the copolymer when the cumulative volume percentage is 84% is 50 to 250 nm, and the non-melt-flowable tetrafluoroethylene copolymer is a non-melt-flowable copolymer of tetrafluoroethylene and at least one comonomer selected from perfluoro(methyl vinyl ether), perfluoro(ethyl vinyl ether), (perfluoroalkyl)ethylene and hexafluoropropylene.
Redispersion sedimentation rate (%) = X ₃ /X ₂ ×100
During the ceremony,
_X2 : The solid sedimentation ratio (%) after redispersion, expressed by the following formula, is obtained by centrifuging 15 g of an aqueous dispersion of a tetrafluoroethylene polymer having the same concentration as the copolymer at 20°C and 3,000 rpm for 30 minutes in a centrifuge and then redispersing the resultant mixture.
_X3 : The percentage of solids sedimented after redispersion (%), as expressed by the following formula, when 15 g of the aqueous dispersion of the copolymer is centrifuged at 20°C and 3,000 rpm for 30 minutes in a centrifuge and then redispersed.
Percentage of solids settling after redispersion (%)
= (amount of settled solids after redispersion)/(mass of solids before centrifugation)×100 The dust suppressant treatment composition for dust-generating substances according to claim 1, wherein the content of perfluorooctanoic acid and its salts in the aqueous dispersion is less than 5 ppb. 3. The dust suppressant treatment composition according to claim 1 , wherein the perfluoroalkyl group in said (perfluoroalkyl)ethylene is a perfluoroalkyl group having 1 to 10 carbon atoms. 3. The dust suppressant treatment composition for dust-generating substances according to claim 1, wherein the (perfluoroalkyl)ethylene is at least one selected from the group consisting of (perfluoroethyl)ethylene, (perfluorobutyl)ethylene, (perfluorohexyl)ethylene, and (perfluorooctyl)ethylene. 3. The dust-suppressing treatment composition for dust-generating substances according to claim 1 , wherein the comonomer is contained in an amount of 0.01 to 1.00% by mass based on the tetrafluoroethylene. 3. The dust-suppressing treatment composition for dust-generating substances according to claim 1 , wherein the comonomer is contained in an amount of 0.01 to 0.50% by mass based on the tetrafluoroethylene. The dust suppressant treatment composition for dust-generating substances according to claim 1 or 2, wherein the copolymer is contained in the dust suppressant treatment composition at a concentration of 10 to 80% by mass. The dust suppressant treatment composition for dust-generating substances according to claim 1 or 2, wherein the copolymer has a specific gravity (SSG) of 2.27 or less. The dust-suppressing treatment composition for dust-generating substances according to claim 1 or 2, wherein the dust-generating substance is a dust-generating powdery substance. A dust suppressant treatment powder for dust-generating substances, comprising a powder obtained by granulating the dust suppressant treatment composition described in claim 1 and then drying it.