Dust suppressant treatment composition

Abstract

The present invention relates to a dust suppression processing agent composition for suppressing dust from dust generating material, the composition comprising an aqueous dispersion of a non-melt flowable tetrafluoroethylene copolymer, wherein the redispersion sedimentation rate of the copolymer is 60% or less and the concentration of perfluorooctanoic acid and a salt thereof is less than 10 ppb relative to the mass of the aqueous dispersion, thereby exhibiting an excellent dust suppressing effect, excellent re-dispersibility of non-melt flowable TFE copolymer particles, i.e. the solid content in the dust suppression processing agent composition after being left to stand for a long time, and excellent environmental performance.

Description

[Technical Field]

[0001] The present invention relates to a dust-suppressing treatment composition that has excellent dust-suppressing properties for dust-generating substances and also has excellent re-dispersibility, and more specifically to a dust-suppressing treatment composition for dust-generating substances that comprises an aqueous dispersion of a non-melt-flowable tetrafluoroethylene (hereinafter referred to as TFE) copolymer, the re-dispersion sedimentation rate of the TFE copolymer being 60% or less, and the content of perfluorooctanoic acid and its salts being less than 10 ppb. [Background technology]

[0002] The technology to suppress dust from dust-producing substances is an important technology 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.

[0003] The TFE polymers described in Patent Document 1 below include Teflon (registered trademark) 6 and Teflon (registered trademark) 30, which are TFE homopolymers in the form of fine powder or emulsion, and Teflon (registered trademark) 6C, which is a modified TFE polymer in the form of fine powder.

[0004] Furthermore, Patent Document 2 listed below proposes a dust suppression method that uses a stable aqueous emulsion containing 1.0 mass % or more of a hydrocarbon-based anionic surfactant relative to a TFE homopolymer (TFE polymer), and shows that this method has a dust suppression effect 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 listed below, i.e., by forcing TFE into an aqueous medium containing a water-soluble polymerization initiator and an anionic surfactant having a fluoroalkyl group as the hydrophobic group (hereinafter referred to as a fluorine-containing emulsifier) ​​as an emulsifier, and polymerizing the TFE, but an emulsion stabilizer is further added to increase stability.

[0005] Furthermore, Patent Document 5 listed below describes a method for suppressing dust without concern for the impact on the environment, in which a dust-suppressing treatment composition comprising a fluorine-containing polymer aqueous dispersion having a fluorine-containing emulsifier content of 50 ppm or less is used, thereby achieving a dust-suppressing effect.

[0006] However, the TFE polymer aqueous dispersions used as dust-suppressing treatment compositions in these methods have the problem that they are prone to settling when left standing for a long period of time, and once settling, the TFE polymer solidifies and is difficult to re-disperse.Furthermore, there is a risk that the TFE polymer concentration in the TFE polymer aqueous dispersion will decrease, and the dust-suppressing effect inherent to the TFE polymer will not be fully exhibited depending on the conditions of use. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Special Publication No. 52-32877 [Patent Document 2] Japanese Patent Application Publication No. 8-20767 [Patent Document 3] Special table 2010-509441 publication [Patent Document 4] Special Publication No. 2010-509442 [Patent Document 5] International Publication No. 2007 / 000812 Summary of the Invention [Problem to be solved by the invention]

[0008] That is, an object of the present invention is to provide a dust-suppressing treatment composition which has an excellent dust-suppressing effect, is excellent in redispersibility of non-melt-flowable TFE copolymer particles, which are the solid content in the dust-suppressing treatment composition, after being left standing for a long period of time, and is also excellent in environmental friendliness. [Means for solving the problem]

[0009] The present invention relates to a non-melt-flowable TFE copolymer aqueous dispersion, in which 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, and the particle size (d84) of the copolymer when the cumulative volume percentage is 84% ​​is 50 to 250 nm. The particle size (d84) when the cumulative volume percentage of the copolymer 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. The present invention provides a dust-suppressing treatment composition for dust-generating substances, which is characterized by:

[0010] Redispersion sedimentation rate (%) = X3 / X2 × 100 (1) During the ceremony, X2: 15 g of an aqueous dispersion of TFE polymer having the same concentration as the copolymer was added at a temperature Centrifuge at 20°C and 3000 rpm for 30 minutes. After centrifugation, when the particles are redispersed, the redispersion rate shown in the following formula (2) Settling rate of solids after dispersion (%) X3: 15 g of the aqueous dispersion of the copolymer was added to a rotating drum at a temperature of 20°C and a rotation speed of 300 After centrifugation at 0 rpm for 30 minutes, the mixture was redispersed. The solid sedimentation rate after redispersion is expressed by the following formula (2) (%) Solid sedimentation rate after redispersion (%) = (amount of settled solids after redispersion) / (amount of solids before centrifugation) × 100 ···(2)

[0011] In a preferred embodiment of the present invention, the amount of perfluorooctanoic acid and salts thereof is less than 5 ppb relative to the mass of the aqueous dispersion.

[0014] In a preferred embodiment of the present invention, the perfluoroalkyl group in the (perfluoroalkyl)ethylene is a perfluoroalkyl group having 1 to 10 carbon atoms.

[0015] In a preferred embodiment of the present invention, the (perfluoroalkyl)ethylene is at least one selected from (perfluoroethyl)ethylene, (perfluorobutyl)ethylene, (perfluorohexyl)ethylene, and (perfluorooctyl)ethylene.

[0018] In a preferred embodiment of the present invention, the comonomer is contained in an amount of 0.01 to 1.00% by mass based on TFE.

[0019] In a preferred embodiment of the present invention, the comonomer is contained in an amount of 0.01 to 0.50% by mass based on TFE.

[0020] In a preferred embodiment of the present invention, the above copolymer is contained in the dust suppressant treatment composition at a concentration of 10 to 80% by mass.

[0021] In a preferred embodiment of the present invention, the specific gravity (SSG) of the copolymer is 2.27 or less.

[0022] The present invention also provides a dust-suppressing treatment powder for dust-generating substances, which comprises a powder obtained by granulating the above-mentioned dust-suppressing treatment composition and then drying it.

[0023] In a preferred embodiment of the present invention, the dust-generating substance is a dust-generating powdery substance. [Effects of the Invention]

[0024] The present invention provides a dust-suppressing treatment composition for dust-generating substances that not only has excellent dust-suppressing properties for dust-generating substances, but also has excellent redispersibility of non-melt-flowable TFE copolymer particles, which are the solid content in the dust-suppressing treatment composition, even after being left to stand for a long period of time, and is also excellent in environmental friendliness. [Brief explanation of the drawings]

[0025] [Figure 1] FIG. 1 shows the results of a centrifugal sedimentation test and a centrifugal sedimentation re-dispersion test for Examples 1 to 3 and Comparative Example 1. [Figure 2] FIG. 1 shows the results of a static sedimentation test and a static sedimentation re-dispersion test for Examples 1 and 2 and Comparative Example 1. [Figure 3] Photographs of Example 2 and Comparative Example 1 after being left standing for 90 days. DETAILED DESCRIPTION OF THE INVENTION

[0026] 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 suppressing 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, tend to settle. Therefore, when an aqueous dispersion of a 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 them by stirring or the like. However, in the dust-suppressing treatment composition of the present invention, the redispersion sedimentation rate of the non-melt-flowable TFE copolymer aqueous dispersion is 60% or less, thereby preventing the settled non-melt-flowable TFE copolymer particles from solidifying, and significantly improving redispersibility. As a result, a small amount of the dust-suppressing treatment composition can be uniformly mixed with dust-generating substances, making it possible to efficiently suppress the generation of dust from dust-generating substances. Furthermore, since the content of persistent perfluorooctanoic acid and its salts is less than 10 ppb, the composition also has excellent environmental performance.

[0027] The excellent dust-suppressing performance and re-dispersibility of the dust suppressant treatment composition of the present invention is also 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.

[0028] (Redispersion sedimentation rate) As is clear from FIG. 1 showing the results of the centrifugal sedimentation test and the centrifugal sedimentation re-dispersion test, the dust suppressant treatment composition of the present invention, in which the re-dispersion sedimentation rate of the non-melt-flowable aqueous TFE copolymer dispersion is 60% or less, has a reduced amount of sedimentation compared to an aqueous TFE polymer dispersion having a re-dispersion sedimentation rate of more than 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 because 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.

[0029] When 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 non-melt-flowable TFE copolymer particles dispersed in the dust-suppressing treatment composition decrease, and in order to maintain the same dust-suppressing performance of dust-generating 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 non-melt-flowable TFE copolymer, which is a useful resource, and also incurs disposal costs, which is undesirable from an economic standpoint.

[0030] (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.

[0031] The (perfluoroalkyl)ethylene preferably has a perfluoroalkyl group having 1 to 10 carbon atoms, more preferably at least one selected from (perfluoroethyl)ethylene, (perfluorobutyl)ethylene, (perfluorohexyl)ethylene, and (perfluorooctyl)ethylene, and even more preferably (perfluorobutyl)ethylene.

[0032] The perfluoro(alkyl vinyl ether) is preferably one in which the perfluoroalkyl group has 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).

[0033] 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, based on 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 amount 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.

[0034] 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 TFE 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 in accordance with ASTM D1238 (372°C, 5 kg load). Such a non-melt-flowable TFE copolymer is different from a TFE copolymer that has melt-flowability and can be melt-formed.

[0035] Furthermore, it is desirable that the specific gravity (SSG) of the non-melt-flowable TFE copolymer be 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-suppressing 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, and the less effective it is at suppressing dust from dust-generating substances, which is undesirable.

[0036] 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 desirably have a particle size (d84) at a cumulative volume percentage of 84% of 250 nm or less, preferably 50 to 250 nm, and more preferably 50 to 225 nm. If d84 is less than 50 nm, the effect of suppressing dust from particulate substances may be reduced compared to when it is within the above range. On the other hand, if d84 exceeds 250 nm, the sedimentation stability (dispersion stability) of the colloidal particles decreases, 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.

[0037] 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%, and 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; a high concentration of the non-melt-flowable TFE copolymer is undesirable because it may impair sedimentation stability (dispersion stability). On the other hand, when transporting a non-melt-flowable TFE copolymer aqueous dispersion, the higher the concentration, the more transportation costs can be saved. Therefore, the concentration of the non-melt-flowable TFE copolymer in the dust suppressant 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.

[0038] In the present invention, the content of perfluorooctanoic acid and its salts in the non-melt-flowable TFE copolymer aqueous dispersion is desirably less than 10 ppb, preferably less than 5 ppb, more preferably 0 ppb, based on the mass of the aqueous dispersion. Since perfluorooctanoic acid and its salts are difficult to decompose and there are concerns about their impact on the environment, it is desirable 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 -20°C freezer, 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 approximately 80 ml of methanol for 7 hours, and measuring the diluted sample liquid by liquid chromatography.

[0039] There are no particular limitations on the method for preparing a non-melt-flowable aqueous dispersion of a TFE copolymer having a content of perfluorooctanoic acid and its salts 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 a polymerization agent during polymerization, but an ammonium salt of a fluoromonoether acid (C3F7-0-CF(CF3)COOH) and an ammonium salt of a fluoropolyether acid (C3F7-O-[CF(CF3)CF2]n-CF(CF3)COOH) are used to polymerize a TFE copolymer.

[0040] In the present invention, the non-melt flowable TFE copolymer in the dust suppression treatment composition for dust-producing substances is a non-melt flowable TFE copolymer of TFE and the above comonomer, and has a redispersion sedimentation rate of 60% or less, so that the copolymer can be fibrillated like a TFE homopolymer to obtain a dust suppression effect, and also can obtain 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, so that the non-melt flowable TFE copolymer aqueous dispersion also has excellent environmental performance.

[0041] 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. As the emulsion stabilizer, a hydrocarbon-based anionic surfactant is preferred. 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.

[0042] 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 NH 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. are preferred examples 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.

[0043] (Dust suppression treatment method) The dust suppression treatment method using the dust suppressant treatment composition of the present invention comprises mixing the dust suppressant 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 suppressing the generation of dust from the dust-generating substance. That is, when the specific non-melt-flowable TFE copolymer used in the present invention is subjected to compression-shear action under the appropriate conditions as described above, it is fibrillated into spider web-like ultrafine fibers, and therefore it is thought that in dust-suppressed treated products 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.

[0044] The dust-producing substances to be treated for dust suppression using 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, shape, etc. 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, mineral powders such as calcium carbonate, dolomite, magnesite, talc, silica stone, and fluorite, clay mineral powders such as kaolin and bentonite, slag powders by-produced in the production processes of metals such as steel and non-ferrous metals, combustion ash powders such as coal and garbage, gypsum powder, powdered metals, carbon black, activated carbon powder, ceramic powders such as metal oxides, pigments, etc. In other words, all dust-producing substances that cause solid particulate matter to scatter and float in the air, generating dust are included.

[0045] 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.

[0046] Furthermore, the dust suppression treatment composition for dust-generating substances of the present invention is preferable from the economical point of view, since the non-melt-flowable TFE copolymer does not solidify strongly even after being left to stand for a long period of time, i.e., it has excellent redispersibility (low redispersion sedimentation rate), which enables reduction in disposal costs.

[0047] Furthermore, by using a dust-suppressing treatment powder for dust-generating substances, which is obtained by granulating the dust-suppressing treatment composition for dust-generating substances of the present invention and then drying it, it is possible to perform dust-proofing treatment on dust-generating substances that are sensitive to moisture due to hygroscopicity or deliquescence, etc. For dust-proofing treatment methods using powders, see, for example, Japanese Patent Publication No. 52-32877. [Example]

[0048] The present invention will be explained 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.

[0049] [1] Particle size at cumulative volume percentage 84% (d84) The particle size (d84) of the non-melt-flowable TFE copolymer particles or the particle size of the TFE polymer particles was measured using a Microtrac UPA150 Model No. 9340 (manufactured by Nikkiso Co., Ltd.).

[0050] [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. After 30 seconds, a final pressure of 350 kg / cm was applied. 2 The pressure was gradually increased to 350 kg / cm 2The resulting preforms (two for each sample) were heated in an air furnace from 290°C to 380°C at a rate of 2°C / min, held at 380°C for 30 minutes, cooled to 294°C at a rate of 1°C / min, held at 294°C for 1 minute, removed from the furnace, 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 gravity 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.

[0051] [3-1] Comonomer content (perfluorobutylethylene (PFBE) content) Using the same method as in [2] above, 0.8±0.050 g of a non-melt-flowable TFE copolymer aqueous dispersion or a dried solid (resin powder) obtained from the TFE polymer aqueous dispersion was placed in a cylindrical mold with a diameter of 2.85 cm and smoothed between aluminum foils. After 30 seconds, the final pressure was 496 kg / cm. 2 The pressure was gradually increased until the final pressure reached 0.03%. 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 PFBE contents (0% by mass and 0.03% by mass). The infrared spectra of these samples were measured, and the absorbance ratio X was calculated using the following equation (3). Absorbance ratio X=(CB) / (AB)...(3) A:936cm -1 Peak height (absorbance) B:887cm -1 Peak height (absorbance) C:875cm -1 Peak height (absorbance) A calibration curve was created from the PFBE content (mass%) and absorbance ratio X of two samples with known PFBE content (mass%), and the PFBE content (mass%) of the sample was calculated from the absorbance ratio X of the sample.

[0052] [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 TFE copolymer aqueous dispersion or a dried solid (resin powder) obtained from the TFE polymer aqueous dispersion was placed in a cylindrical mold with a diameter of 2.85 cm, smoothed between aluminum foils, and pressure was applied for 30 seconds, gradually increasing until the final pressure reached 1470 kg / cm. 2 The final pressure was applied until the final pressure reached 0.001, and this pressure was maintained for 2 minutes to obtain 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 X1 = (absorbance ratio of sample 1 / absorbance ratio of known resin powder) × 0.75 (4) Absorbance ratio=B1 / A1...(5) A1:936cm -1 Peak height (absorbance) B1:994cm -1 Peak height (absorbance) A calibration curve was created from the PPVE content (mass%) and absorbance ratio X1 of two samples with known PPVE content (mass%), and the PPVE content (mass%) of the sample was calculated from the absorbance ratio X1 of the sample.

[0053] [3-3] Comonomer content (hexafluoropropylene (HFP) content) Using the same method as in [2] above, a 1.75±0.005 g sample of a non-melt-flowable TFE copolymer aqueous dispersion or a dried solid (resin powder) obtained from the TFE polymer aqueous dispersion was placed in a cylindrical mold with a diameter of 2.85 cm, smoothed between aluminum foils, and gradually increased pressure was applied for 30 seconds until the final pressure reached 1470 kg / cm. 2The final pressure was applied until the final pressure reached 0.06%, and this 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: 0.06%, 0.08%, and 0.12% by mass). The infrared spectra of these samples were measured, and the absorbance ratio and absorbance ratio X2 were calculated using the following equations (6) and (7). Absorbance ratio x2 = (absorbance ratio of sample / absorbance ratio of known sample) x 0.42 ···(6) Absorbance ratio = B2 / A2 (7) A2:936cm -1 Peak height (absorbance) B2:983cm -1 Peak height (absorbance) A calibration curve was created from the HFP content (mass%) and absorbance ratio X2 of three samples with known HFP content (mass%), and the HFP content (mass%) of each sample was calculated from the absorbance ratio X2 of the sample.

[0054] [4] Solid content mass% Less than 6 g of non-melt-flowable TFE copolymer aqueous dispersion or TFE polymer aqueous dispersion was weighed into a tared aluminum dish, and the mass of the non-melt-flowable TFE copolymer aqueous dispersion or TFE polymer aqueous dispersion (mass before drying) was measured (measured to four decimal places). The mixture was then left to stand in a 105°C dryer for 2 hours to remove moisture, baked in a constant-temperature oven at 380°C for 20 minutes, cooled to room temperature, and then its mass (mass after drying) was measured, and the solids content (mass%) was calculated using the following formula (8): Solid mass% = [(mass after drying - tare mass of aluminum dish) / mass before drying] x 100···(8)

[0055] [5] Melting point Using the same method as described 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 the TFE polymer aqueous dispersion was placed in a Super Clean aluminum sample pan (PerkinElmer Japan Co., Ltd.), a cover was placed on top, and the pan was sealed using a standard crimper press to prepare a measurement sample. The calorific value of the measurement sample was measured using a power compensation differential scanning calorimeter, Diamond DSC (PerkinElmer Japan Co., Ltd.), with an empty Super Clean aluminum sample pan as the reference material, while increasing the temperature from 200°C to 370°C at a rate of 10°C per minute. The temperature at which the observed endothermic peak reached its maximum was determined as the melting point of the measurement sample (resin powder).

[0056] [6] Centrifugal sedimentation test 15 g of a non-melt-flowable TFE copolymer aqueous dispersion or TFE polymer aqueous dispersion having the composition shown in Table 1 was placed in a centrifuge tube (15 ml centrifuge tube, manufactured by Corning Inc.) 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. The centrifuge tube was left 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 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 solid sedimentation amount. The solid sedimentation ratio was calculated using the following formula (10), and the sedimentation rate was calculated using the following formula (9).

[0057] Sedimentation rate = X1 / X0 × 100 (9) During the ceremony, X0: 15 g of the aqueous dispersion of the TFE polymer shown in Comparative Example 1 was heated at 20°C. Centrifuge at 3000 rpm for 30 minutes. After that, the liquid portion other than the solid matter that settled at the bottom of the centrifuge tube (the supernatant and the settled part) The solid content (unreacted solid content) is calculated by the following formula (10) The sedimentation rate (%). X1: 15 g of a non-melt-flowable TFE copolymer aqueous dispersion shown in the examples Centrifuge at 20°C and 3000 rpm for 30 minutes. After centrifugation, the solid matter that had settled to the bottom of the centrifuge tube (liquid portion: The following formula (10) is used when removing the supernatant and unsettled solids. The solid sedimentation rate (%) is Solid sedimentation rate (%) = (amount of settled solids) / (mass of solids before centrifugation) × 100 (10)

[0058] [7] Centrifugal redispersion test In the above [6], the mass of the centrifuge tube from which the liquid portion was removed 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 the 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 to calculate the amount of solids that had settled after redispersion. The solids settling ratio after redispersion was calculated using the following formula (2'), and the redispersion settling rate was calculated using the following formula (1').

[0059] Redispersion sedimentation rate (%) = X3 / X2 × 100 (1') During the ceremony, X2: 15 g of the aqueous dispersion of the TFE polymer shown in Comparative Example 1 was added at a temperature of 20°C. Centrifuge at 3000 rpm for 30 minutes. After that, when the solids were redispersed, the sedimentation rate of the solids was calculated as shown in the following formula (2'). The percentage is as follows: X3: 15 g of the non-melt-flowable TFE copolymer aqueous dispersion shown in the examples Centrifuge at 20°C and 3000 rpm for 30 minutes. After further centrifugation, the resulting mixture was redispersed, as shown in the following formula (2'). The solid sedimentation rate (%). Solid sedimentation rate after redispersion (%) = (amount of settled solids after redispersion) / (mass of solids before centrifugation) × 100 (2')

[0060] [8] Static settling test As shown in Table 2, 15 g of a non-melt-flowable aqueous TFE copolymer dispersion or aqueous TFE polymer dispersion was placed in a centrifuge tube, and after closing the tube, the tube was allowed to stand at room temperature for 30, 60, or 90 days. After standing for 30, 60, or 90 days, the tube was opened, and everything except the settled solids (liquid portion: supernatant and unsettled solids) was removed. The tube was then left upside down for 30 minutes, and 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 settled solids after standing. The solid sedimentation ratio was calculated using the following formula (12), and the sedimentation rate was calculated using the following formula (11).

[0061] Sedimentation rate=X5 / X4×100...(11) During the ceremony, X4: 15 g of the TFE polymer aqueous dispersion shown in Comparative Example 1 was placed in a centrifuge tube with the opening closed. After that, they were left at room temperature for 30 days, 60 days, and 90 days. After that, the liquid portion other than the precipitated solids (the supernatant and the Remove the remaining solids, then leave the centrifuge tube upside down for 30 minutes. The solid sedimentation rate (% ) X5: 15 g of the non-melt-flowable TFE copolymer aqueous dispersion shown in the examples After closing the centrifuge tube, the tube was left for 30 days, 60 days, and 90 days, respectively. After leaving it at room temperature, all the solids except for the precipitated solids (liquid part: supernatant and Remove the remaining solids (and any remaining solids) and place the centrifuge tube upside down for 30 minutes. After leaving it to stand for a while and further removing the liquid portion, the amount of solids that settled after leaving it to stand (mass) The solid sedimentation rate (%) is calculated based on the following formula (12): . Solid sedimentation rate (%) = (amount of settled solids after standing) / (mass of solids before standing) × 100 ···(12)

[0062] [9] Static settling and redispersion test The mass of the test tube left standing in [8] 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, everything except the solids that had settled to the bottom of the centrifuge tube (the liquid portion and the redispersed solids) was removed, and the centrifuge tube was left standing upside down for 30 minutes to further remove the liquid portion. The mass (the sum of the mass of the centrifuge tube and the amount of 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 to calculate the amount of solids that had settled after redispersion. The redispersed solids sedimentation ratio was calculated using the following formula (14), and the redispersion sedimentation rate was calculated using the following formula (13).

[0063] Redispersion sedimentation rate = X7 / X6 × 100 (13) During the ceremony, X6: 15 g of the TFE polymer aqueous dispersion shown in Comparative Example 1 was placed in a centrifuge tube with the opening closed. After that, they were left at room temperature for 30 days, 60 days, and 90 days. After that, the liquid portion other than the precipitated solids (the supernatant and the Remove the remaining solids, then leave the centrifuge tube upside down for 30 minutes. After further removing the solids, the solids are redispersed as shown in the following formula (14). The sedimentation rate (%) is the percentage of the shape. X7: 15 g of the non-melt-flowable TFE copolymer aqueous dispersion shown in the examples After closing the centrifuge tube, the tube was left for 30 days, 60 days, and 90 days, respectively. After leaving it at room temperature, all the solids except for the precipitated solids (liquid part: supernatant and Remove the remaining solids (and any remaining solids) and place the centrifuge tube upside down for 30 minutes. After leaving the mixture to stand for a while and further removing the liquid portion, the following formula (14 ) is the solids settling percentage (%). Solid sedimentation rate after redispersion (%) = (amount of settled solids after redispersion) / (mass of solids before centrifugation) × 100 ···(14)

[0064]

[10] Falling dust test (amount of falling dust) 200 g of sample (dust suppression treated material) 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 height of 45 cm from the bottom was measured using a scattered light digital dust meter. The amount of suspended dust was measured five times in a row for one minute after the sample was added, and the geometric mean value x (CPM) obtained by subtracting the value measured before adding the sample (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 this falling dust amount (CPM) is 50 or less, the dustproof performance is more excellent, which is more preferable.

[0065] 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 (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 autoclave was heated to 80°C and purged with nitrogen gas three times to remove oxygen. After that, a vacuum was drawn. 4.4 g of PFBE, 0.2 g of the ammonium salt of fluoromonoether acid, and 199.8 ml of deionized water were then added. Tetrafluoroethylene (TFE) was then added 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.

[0066] Next, 100 ml of an aqueous solution was pumped in from an aqueous solution prepared by dissolving 0.12 g of ammonium persulfate in 400 ml of water. After the injection of the ammonium persulfate aqueous solution was completed, TFE was continued to be supplied so as to maintain the internal pressure at 2.0 MPa. When the consumption of TFE reached 1106.79 g, stirring was stopped. The gas in 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 TFE copolymer aqueous dispersion.

[0067] The resulting non-melt-flowable TFE copolymer aqueous dispersion was measured for particle size (d84) at a cumulative volume percentage of 84%, SSG, PFBE content, solid 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.

[0068] Examples 2 and 3 A non-melt-flowable aqueous TFE copolymer 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, solids mass, melting point, and amount of perfluorooctanoic acid and its salts were measured for the obtained non-melt-flowable aqueous TFE copolymer dispersion. A centrifugal sedimentation test and a centrifugal sedimentation redispersion test were also conducted. The results are shown in Table 1 and FIG. 1.

[0069] (Comparative Example 1) For a TFE polymer aqueous 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. A centrifugal sedimentation test and a centrifugal sedimentation redispersion test were also conducted. Physical property analysis was also performed in the same manner as in Example 1. The results are shown in Table 1 and Figure 1.

[0070] Furthermore, a static settling test and a static settling redispersion test were carried out 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 being left standing for 90 days.

[0071] (Dust fall 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 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 was 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 generated by the hydration reaction of the quicklime, and after approximately two minutes, 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 mixing, the mixer was stopped. The temperature at this time was measured with a thermometer and was 107°C. This dust-suppressed quicklime was a mixture of quicklime and slaked lime, with approximately 30% of the slaked lime newly produced by the hydration reaction. The dust-suppressed The treated material was subjected to a falling dust test, and the results are shown in Table 3.

[0072] (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 (% by mass of solids relative to the dust-generating substance) shown in Table 3, 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 dispersion was 100 g. A dust-suppressed treated mixture of quicklime and slaked lime was obtained in the same manner as in Example 4. A drop dust generation test was conducted on the obtained dust-suppressed treated product. The results are shown in Table 3.

[0073] (Comparative Example 5) A drop dusting 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.

[0074] [Table 1]

[0075] [Table 2]

[0076] [Table 3]

[0077] 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 (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 autoclave was heated to 80°C and purged with nitrogen gas three times to remove oxygen. The system was then evacuated. The comonomer (HFP or PPVE) was then pumped in the amount listed in Table 4. Tetrafluoroethylene (TFE) was then introduced 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.

[0078] Next, 100 ml of an aqueous solution was pumped in from an aqueous solution prepared by dissolving 0.12 g of ammonium persulfate in 400 ml of water. After the injection of the ammonium persulfate aqueous solution was completed, TFE was continued to be supplied so as to maintain the internal pressure at 2.0 MPa. When the consumption of TFE reached 1106.79 g, stirring was stopped. The gas in 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 TFE copolymer aqueous dispersion.

[0079] The resulting non-melt-flowable TFE copolymer aqueous dispersion was measured for particle size (d84) at a cumulative volume percentage of 84%, SSG, PFBE content, solid 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.

[0080] (Examples 14, 15, 21, 23, 24, 29, 30, 32 to 35) The dust-producing substances 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 100 g. Dust-suppressing treated products were obtained by the following method. The obtained dust-suppressing treated products were subjected to a drop dust generation test. The results are shown in Table 5 or Table 6.

[0081] (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.

[0082] <Dusting substances> Powdered quicklime (containing 96.0% CaO and 0.9% MgO) (Powdered quicklime that passed through a 2.0mm standard mesh sieve completely, 0.18% on a 1.0mm standard mesh sieve, 2.48% on a 600μm standard mesh sieve, 20.44% on a 300μm standard mesh sieve, 20.58% on a 150μm standard mesh sieve, and 56.32% passed through a 150μm 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 low speed, the dispersion diluted with water (the mass of the non-melt-flowable TFE copolymer corresponding to the amount added shown in Table 5 + 100 g of water) was added to 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.

[0083] Ordinary Portland cement (contains 64.3% CaO, 1.1% MgO, 20.5% SiO2, 5.1% Al2O3, 3.1% Fe2O3, and 2.0% SO3) (Ordinary Portland cement that passes 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 one 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 one 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 three minutes in the mortar mixer to obtain a dust-suppressing treated product.

[0084] ·Anhydrite (Anhydrous gypsum that passed through a 2.0 mm standard mesh sieve, passed through a 1.0 mm standard mesh sieve, retained 0.13% on a 600 μm standard mesh sieve, retained 0.22% on a 300 μm standard mesh sieve, retained 11.33% on a 150 μm standard mesh sieve, and passed through a 150 μm standard mesh sieve with 88.31% passing through) Dust-proofing treatment of anhydrous gypsum (Examples 17 and 26): Two 500g portions of anhydrous gypsum were weighed, spread evenly on an enamel tray, and heated at 105°C for one day and night. 500g 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 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 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 1kg of the mixture was placed in a mortar and stirred with a pestle for 9 minutes to obtain a dust-suppressing treated product.

[0085] 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 (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.

[0086] Dolomite (Dolomite that passed through a 2.0 mm standard mesh sieve completely, 0.06% remaining on a 1.0 mm standard mesh sieve, 0.50% remaining on a 600 μm standard mesh sieve, 3.44% remaining on a 300 μm standard mesh sieve, 8.20% remaining on a 150 μm standard mesh sieve, and 87.79% passing 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 at 105°C for one day and night. 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.

[0087] Lignite powder (Lignite powder that passed through a 2.0 mm standard mesh sieve, a 1.0 mm standard mesh sieve, 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 (hygroscopic dust-generating powder) was weighed out, spread evenly on an enamel tray, and heated at 105°C for one day and night. 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 the 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 was completely removed, and 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 1 / 4-portions and mixed, after which the mixture was 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.

[0088] [Table 4]

[0089] [Table 5]

[0090] [Table 6] [Industrial Applicability]

[0091] The dust-suppressing treatment composition of the present invention is suitably used for dust-suppressing treatment of dust-generating substances to obtain dust-suppressed treated products of dust-generating substances in the fields of building materials, soil stabilizers, solidifying materials, fertilizers, landfill disposal of incineration ash or hazardous substances, explosion prevention, cosmetics, and fillers for various plastics.

Claims

1. 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, X ２ The percentage of solids sedimented after redispersion (%) is calculated by the following formula when 15 g of an aqueous dispersion of a tetrafluoroethylene polymer having the same concentration as the copolymer is centrifuged at 20°C and 3,000 rpm for 30 minutes in a centrifuge and then redispersed. X ３ The percentage of solid sedimentation after redispersion (%) is calculated 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 and then redispersed. Percentage of solids settling after redispersion (%) = (amount of settled solids after redispersion) / (mass of solids before centrifugation)×100

2. 2. The dust-suppressing treatment composition for dust-generating substances according to claim 1, wherein the content of said perfluorooctanoic acid and its salts in said aqueous dispersion is less than 5 ppb.

3. 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.

4. 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.

5. 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.

6. 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.

7. 3. The dust-suppressing treatment composition for dust-generating substances according to claim 1, wherein the copolymer is contained in the dust-suppressing treatment composition at a concentration of 10 to 80% by mass.

8. 3. The dust-suppressing treatment composition for dust-generating substances according to claim 1, wherein the copolymer has a specific gravity (SSG) of 2.27 or less.

9. 3. The dust-suppressing treatment composition for dust-generating substances according to claim 1, wherein the dust-generating substance is a dust-generating powdery substance.

10. 2. A dust-suppressing treatment powder for dust-generating substances, which comprises a powder obtained by granulating the dust-suppressing treatment composition according to claim 1 and then drying it.

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