WO2023106288A1 - Dust suppression treatment method - Google Patents

Abstract

The present invention relates to a dust suppression treatment method for suppressing dust from a dust-producing substance, characterized in that a dust suppression treatment agent composition composed of a non-melt-flowable tetrafluoroethylene copolymer aqueous dispersion is used, the redispersion sedimentation rate of the copolymer being 60% or less, and the amount of perfluorooctanoic acid and salts thereof being less than 10 ppb relative to the mass of the aqueous dispersion, the dust suppression treatment agent composition is mixed with a dust-producing substance, and the mixture is subjected to compression-shear action at a temperature of 20-200°C, whereby the tetrafluoroethylene copolymer is fibrillated to suppress the generation of dust by the dust-producing substance. The dust suppression treatment method has an exceptional dust suppression effect, exhibits exceptional redispersibility of the non-melt-flowable tetrafluoroethylene copolymer particles, which are the solids fraction in the dust suppression treatment agent composition, after said composition is allowed to stand for a long period of time, and additionally exhibits exceptional environmental performance.

Description

Dust suppression treatment method

TECHNICAL FIELD The present invention relates to a dust suppression treatment method using a dust suppression treatment agent composition that has excellent performance in suppressing dust from dust-generating substances and is also excellent in redispersibility. Dust composed of a fluoroethylene (hereinafter referred to as TFE) copolymer aqueous dispersion, the redispersion sedimentation rate of the TFE copolymer being 60% or less, and the content of perfluorooctanoic acid and its salts being less than 10 ppb. The present invention relates to a method for dust suppression treatment of dust-generating substances using a dust suppression treatment agent composition.

Technology for controlling dust in dust-producing materials is an important technology for human life and industry for health, safety, environmental and other requirements.
As such a dust suppression technology, in Patent Document 1 below, PTFE (TFE polymer) is mixed with a powdery substance, and the mixture is subjected to a compression-shearing action at a temperature of about 20 to 200 ° C. to make TFE heavy. Methods have been proposed for suppressing dusting of powdery substances by fibrillating coalescence.

The TFE polymer described in Patent Document 1 below is a homopolymer of TFE as a composition, Teflon (registered trademark) 6 or Teflon (registered trademark) 30 as a fine powder or emulsion as a composition, and TFE as a composition. It is a modified polymer of Teflon (registered trademark) 6C, which is a fine powder.

Further, in the following Patent Document 2, a dust suppression method using a stable aqueous emulsion containing 1.0% by mass or more of a hydrocarbon-based anionic surfactant with respect to a homopolymer of TFE (TFE polymer) is used. has been proposed and shown to have a dust-suppressing effect on powdery substances. According to Patent Document 2, particles of the TFE polymer are prepared by the emulsion polymerization method disclosed in Patent Documents 3 and 4 below, that is, an anionic interface using TFE as a water-soluble polymerization initiator and a fluoroalkyl group as a hydrophobic group. It is produced in the form of an aqueous emulsion by injecting an active agent (hereinafter referred to as a fluorine-containing emulsifier) into an aqueous medium containing an emulsifier and polymerizing it, and an emulsion stabilizer is added to increase the stability. .

Furthermore, Patent Document 5 below discloses that the use of a dust-suppressing treatment agent composition comprising an aqueous dispersion of a fluoropolymer having a fluorine-containing emulsifier content of 50 ppm or less has a dust-suppressing effect and is environmentally friendly. A method is described that can suppress dust without worrying about its effects.

However, the TFE polymer aqueous dispersion used as the dust-suppressing treatment agent composition in these methods tends to settle when left standing for a long period of time, and once the TFE polymer settles, it solidifies and is difficult to redisperse. In addition to this problem, depending on the conditions of use, the TFE polymer concentration in the TFE polymer aqueous dispersion may be lowered, and the dust-suppressing effect originally provided by the TFE polymer may not be fully exhibited. rice field.

Japanese Patent Publication No. 52-32877 JP-A-8-20767 Japanese Patent Publication No. 2010-509441 Japanese Patent Publication No. 2010-509442 International publication WO2007/000812

That is, the present invention has an excellent dust suppressing effect and is also excellent in redispersibility of the non-melt-flowable TFE copolymer, which is a solid content in the dust suppressing treatment agent composition after standing for a long period of time. Further, it is an object of the present invention to provide a dust suppression treatment method using a dust suppression treatment agent composition which is excellent in environmental performance.

The present invention comprises a non-melt-flowable TFE copolymer aqueous dispersion, the copolymer represented by the following formula (1) has a redispersion sedimentation rate of 60% or less, and the perfluoropolymer in the aqueous dispersion Using a dust suppressing treatment agent composition containing less than 10 ppb of octanoic acid and its salts, the dust suppressing treatment agent composition is mixed with a dust-generating substance, and the mixture is heated at a temperature of 20 to 200°C. Provided is a method for suppressing dust from a dust-generating substance, comprising fibrillating a TFE copolymer by subjecting it to compression-shearing action to suppress generation of dust from the dust-generating substance.

Redispersion sedimentation rate (%) = X ₃ /X ₂ × 100 (1)
During the ceremony,
X ₂ : 15 g of a TFE polymer aqueous dispersion having the same concentration as the copolymer was heated to 2
Solid content sedimentation ratio (%) after redispersion shown by the following formula (2) when redispersed after centrifugation with a centrifuge at 0°C and a rotation speed of 3000 rpm for 30 minutes
X ₃ : 15 g of the aqueous copolymer dispersion was heated to 20°C and rotated at 3000
After centrifuging with a centrifuge for 30 minutes at rpm, when re-dispersed, the solid content sedimentation ratio after re-dispersion indicated by the following formula (2) (%)
Solid sedimentation ratio after redispersion (%)
= (Amount of sedimentation of solid content after redispersion) / (Amount of solid content before centrifugation) x 100
... (2)

It is a preferred aspect of the present invention that the content of the perfluorooctanoic acid and its salt in the aqueous dispersion is less than 5 ppb.

It is a preferred embodiment of the present invention that the particle size (d84) is 250 nm or less when the cumulative volume percentage of the copolymer is 84%.

The non-melt-flowable TFE copolymer is a non-melt-flowable copolymer of TFE and at least one comonomer selected from (perfluoroalkyl)ethylene, perfluoro(alkyl vinyl ether), and hexafluoropropylene. Being polymeric is a preferred aspect of the present invention.

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

The (perfluoroalkyl)ethylene is at least one selected from (perfluoroethyl)ethylene, (perfluorobutyl)ethylene, (perfluorohexyl)ethylene, and (perfluorooctyl)ethylene. This is a preferred embodiment of the invention.

It is a preferred embodiment of the present invention that the perfluoroalkyl group in the perfluoro(alkyl vinyl ether) is a perfluoroalkyl group having 1 to 10 carbon atoms.

It is a preferred embodiment of the present invention that the perfluoro(alkyl vinyl ether) is at least one selected from perfluoro(methyl vinyl ether), perfluoro(ethyl vinyl ether), and perfluoro(propyl vinyl ether). .

It is a preferred embodiment of the present invention that the comonomer is contained in an amount of 0.01 to 1.00% by mass with respect to TFE.

It is a preferred aspect of the present invention that the comonomer is contained in an amount of 0.01 to 0.50% by mass with respect to TFE.

It is a preferred embodiment of the present invention that the copolymer is contained at a concentration of 10 to 80% by mass with respect to the dust suppressing treatment agent composition.

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-inhibiting treatment method for a dust-generating substance using a dust-inhibiting treatment agent powder obtained by granulating and then drying the dust-inhibiting treatment agent composition.

The dust suppression treatment method of the present invention can be suitably used for a dust-generating powdery substance as the dust-generating substance.

According to the present invention, non-melt-flowable TFE copolymer particles that are excellent in the performance of suppressing dust from dust-generating substances and are a solid content in the dust-suppressing treatment agent composition even after being left standing for a long period of time. Provided is a method for dust control treatment of dust-generating substances using a dust control agent composition having excellent redispersibility and environmental performance.

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

The dust suppression treatment method for dust-generating substances of the present invention comprises a non-melt-flowable TFE copolymer aqueous dispersion, and 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 salt in the aqueous dispersion is less than 10 ppb, and the dust suppressing treatment composition and the dust-generating substance are mixed, It is important in the present invention to fibrillate the non-melt-flowable TFE copolymer by subjecting the mixture to a compression-shearing action at a temperature of about 20 to 200° C. to suppress the generation of dust from dust-generating substances. It is a feature.
As described above, the TFE polymer particles, which are the solid content in the dust-controlling agent composition, tend to settle. The sedimented TFE polymer particles solidify and are difficult to redisperse by stirring or the like. By using a dust suppressing treatment composition having a redispersion sedimentation rate of 60% or less, the sedimented non-melt-flowable TFE copolymer particles are suppressed from firmly solidifying, and the redispersibility is remarkably improved. It becomes possible to As a result, in the dust suppressing treatment method of the present invention, a small amount of the dust suppressing agent composition can be uniformly mixed with the dust-generating substance, so that the generation of dust from the dust-generating substance can be efficiently suppressed. becomes possible. Furthermore, since the content of persistent perfluorooctanoic acid and its salts is less than 10 ppb, it is also excellent in environmental performance.

The fact that the dust suppressing treatment agent composition used in the present invention has excellent redispersibility in addition to dust suppressing performance is confirmed by the centrifugal sedimentation test, the centrifugal redispersion test, and the stationary sedimentation test of Examples described later. , static sedimentation redispersion test, and falling dust generation test.

(Redispersion sedimentation rate)
As is clear from FIG. 1 showing the results of the centrifugal sedimentation test and the centrifugal sedimentation redispersion test, the redispersion sedimentation rate of the non-melt-flowable TFE copolymer aqueous dispersion used in the present invention is 60% or less. Certain dust control treatment compositions have a reduced amount of sedimentation compared to aqueous TFE polymer dispersions with a redispersion sedimentation rate of greater than 60%.
Further, as shown in Examples 1 to 3 described later, the dust suppression treatment method of the present invention is represented by the above formula (1) of the non-melt-flowable TFE copolymer aqueous dispersion in the dust suppression treatment agent composition to be used. It is clear that good redispersion can be achieved when the redispersion sedimentation rate is 60% or less, preferably 50% or less, preferably 30% or less. Furthermore, it is believed that the non-melt-flowable TFE copolymer in the dust-suppressing treatment agent composition used in the present invention has excellent sedimentation stability because it contains few rod-like particles that easily sediment.

If the redispersion sedimentation rate shown by the above formula (1) exceeds 60%, the sedimented non-melt-flowable TFE copolymer particles solidify and become difficult to redisperse. In addition, as a result of the sedimentation of the non-melt-flowable TFE copolymer particles that are the solid content, the amount of the non-melt-flowable TFE copolymer particles dispersed in the dust suppressing treatment agent composition is reduced, and is equivalent to that before sedimentation. To maintain the dust-suppressing performance of the dust-producing material, more non-melt-flowable TFE copolymer aqueous dispersion is required. In addition, the strongly solidified non-melt-flowable TFE copolymer cannot be used as a dust control agent and must be discarded. It is not preferable from an economical point of view because it wastes a large amount and generates a disposal cost.

(Non-melt-flowable TFE copolymer)
The non-melt-flowable TFE copolymer of the present invention is a non-melt-flowable TFE copolymer of tetrafluoroethylene and at least one comonomer selected from perfluoro(alkylvinyl ether), (perfluoroalkyl)ethylene, and hexafluoropropylene. A fluid copolymer is preferred.

In the (perfluoroalkyl)ethylene, the perfluoroalkyl group in (perfluoroalkyl)ethylene is preferably a perfluoroalkyl group having 1 to 10 carbon atoms, more preferably (perfluoroethyl)ethylene, ( It is at least one selected from perfluorobutyl)ethylene, (perfluorohexyl)ethylene, and (perfluorooctyl)ethylene. More preferred is (perfluorobutyl)ethylene.

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

The amount of the comonomer in the non-melt-flowable TFE copolymer used in the present invention is 0.01 to 1.00% by mass, preferably 0.01 to 0.50% by mass, more preferably 0.01 to 0.50% by mass, based on TFE. It is contained in an amount of 01 to 0.30% by mass. When the content of the comonomer is 0.01 to 1.00% by mass, the stability of the aqueous dispersion is improved because there are few rod-shaped particles that tend to settle in the solid content. On the other hand, if the content of the comonomer exceeds 1.00% by mass, fibrillation becomes difficult and thermal stability decreases, which is not preferable. Moreover, when the content of the comonomer is less than 0.01% by mass, the effect of the comonomer cannot be expected, and the redispersion sedimentation rate is inferior, which is not preferable.

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

Also, the specific gravity (SSG) of the non-melt-flowable TFE copolymer is desirably 2.27 or less, preferably 2.22 or less, and more preferably 2.20 or less. The higher the SSG value, the lower the molecular weight, and the lower the SSG value, the higher the molecular weight. A high dust suppression effect can be obtained. On the other hand, the larger the SSG value (exceeding 2.27), that is, the smaller the molecular weight, the more difficult it becomes to fibrillate, and the dust suppressing effect of the dust-generating substance is inferior, which is not preferable.

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 non-melt-flowable TFE copolymer fine particles in the aqueous dispersion have a particle size (d84) of 250 nm or less, preferably 50 to 250 nm, more preferably 50 to 225 nm when the cumulative volume percentage is 84%. is desirable. When d84 is less than 50 nm, the effect of dust-generating substances in suppressing dust may be lower than when d84 is within the above range. (dispersion stability) is lowered, which is not preferable.
When the particle size (d84) is 250 nm or less, unlike the case where the particle size (d50) is 250 nm or less, it means that there are no extremely large primary particles, and the sedimentation stability of the aqueous dispersion is excellent. means that

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 10 to 80% by mass, preferably 15 to 80% by mass, or more. It is preferably in the range of 20 to 80% by mass.
In order to enhance the effect of dispersing the non-melt-flowable TFE copolymer in the dust-generating substance, the lower the concentration of the non-melt-flowable TFE copolymer, the better. If it is too high, the sedimentation stability (dispersion stability) may be impaired, which is not preferable. On the other hand, when transporting the non-melt-flowable TFE copolymer aqueous dispersion, the higher the concentration, the more the transport cost can be saved. Therefore, the concentration of the non-melt-flowable TFE copolymer in the dust-suppressing treatment agent composition used in the present invention is preferably 10% by mass or more, particularly in the range of 20 to 80% by mass.
In addition, when mixing with the dust-generating substance, in order to enhance the dispersion effect of the non-melt-flowable TFE copolymer in the dust suppressing treatment agent composition used in the present invention, the non-melt-flowable TFE copolymer It is also possible to dilute the dust suppressing treatment composition with water so that the concentration is 5% by mass or less.

The content of perfluorooctanoic acid and its salt in the non-melt-flowable TFE copolymer aqueous dispersion used in the present invention is less than 10 ppb, preferably less than 5 ppb, more preferably 0 ppb based on the mass of the aqueous dispersion. It is desirable to have Since perfluorooctanoic acid and its salts are difficult to decompose and have environmental impact, it is desired that their content be as low as possible.
The concentration of perfluorooctanoic acid and its salt in the non-melt-flowable TFE copolymer aqueous dispersion was measured by placing 10 ml of the non-melt-flowable TFE copolymer aqueous dispersion in a polyethylene container in a freezer at -20°C. After freezing to agglomerate the non-melt-flowable TFE copolymer and separating it from water, the contents of the polyethylene container were all transferred to a Soxhlet extractor, extracted with about 80 ml of methanol for 7 hours, and diluted to a volume. The concentration of perfluorooctanoic acid and its salts in the non-melt-flowable TFE copolymer aqueous dispersion can be calculated by measuring the sample liquid with a liquid chromatograph.

The method for preparing the non-melt-flowable TFE copolymer aqueous dispersion containing less than 10 ppb of perfluorooctanoic acid and its salt is not particularly limited, but the following method can be exemplified.
For example, as disclosed in Patent Documents 3 and 4 mentioned above, perfluorooctanoic acid and its salts are not used as polymerization agents during polymerization, and fluoromonoether acids (C ₃ F ₇ -O-CF ( The ammonium salt of CF ₃ )COOH) and the ammonium salt of fluoropolyether acid (C ₃ F ₇ -O-[CF(CF ₃ )CF ₂ ]n-CF(CF ₃ )COOH) were used to prepare the TFE copolymer. A method of polymerization can be mentioned.

The non-melt-flowable TFE copolymer in the dust suppressing treatment agent composition used in the present invention is a non-melt-flowable TFE copolymer of TFE and the above-mentioned comonomer, and has a redispersion sedimentation rate of 60% or less. As a result, it becomes possible to obtain an excellent redispersion sedimentation rate in addition to being able to fibrillate similarly to the non-melt-flowable TFE polymer and to obtain a dust suppressing effect. In addition, since the content of perfluorooctanoic acid and its salt in the non-melt-flowable TFE copolymer aqueous dispersion is less than 10 ppb, it also has excellent environmental performance.

Furthermore, the dust-controlling agent composition, which is a non-melt-flowable TFE copolymer aqueous dispersion used in the present invention, contains an emulsion stabilizer in order to increase the stability of the non-melt-flowable TFE copolymer aqueous dispersion. may contain. Hydrocarbon anionic surfactants are preferred as emulsion stabilizers. Since this surfactant essentially forms an insoluble or sparingly soluble salt in water with calcium, aluminum and iron, which are components in the soil, it is possible to avoid pollution of rivers, lakes and groundwater caused by surfactants. I can.

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, alkylaryl There are sulfonates and the like, especially polyoxyethylene alkylphenyl ether ethylene sulfonic acid (n of polyoxyethylene is 1 to 6, alkyl has 8 to 11 carbon atoms), alkylbenzene sulfonic acid (alkyl has 10 to 10 carbon atoms), 12) Na, K, Li and _NH4 salts such as dialkyl sulfosuccinates (alkyl has 8-10 carbon atoms) impart high mechanical stability to non-melt-flowable TFE copolymer aqueous dispersions. is possible, and the non-melt-flowable TFE copolymer particles are prevented from aggregating due to high-speed agitation or the like, so it can be exemplified as a preferable one.

(Dust suppression treatment method)
In the dust control treatment method of the present invention, the dust control agent composition is mixed with a dust-generating substance, the mixture is subjected to compression-shearing action at a temperature of 20 to 200° C., preferably 50 to 150° C., and the composition is By fibrillating the non-melt-flowable TFE copolymer in the product, it is possible to suppress the generation of dust from dust-generating substances.
That is, when the specific non-melt-flowable TFE copolymer used in the present invention is subjected to compression-shearing action under appropriate conditions as described above, it fibrillates in a spider web-like manner and becomes ultrafine fibers. In the dust-suppressing treated material treated using the dust-suppressing treatment method, it is considered that the dust-generating substances are captured and aggregated by the spider web-like fine fibers to suppress dust.

The dust-generating substance to be dust-reduced by the dust-reducing treatment method of the present invention is an inorganic and/or organic dust-generating substance, and there are no particular restrictions on the substance, shape, and the like. The present invention can also be effectively applied to dust-generating powdery substances as dust-generating substances. Dust-producing substances that can be particularly preferably treated include, for example, cements such as Portland cement and alumina cement, slaked lime, quicklime powder, mineral powders such as calcium carbonate, dolomite, magnesite, talc, silica, and fluorite, Clay mineral powder such as kaolin and bentonite, metals such as iron and steel, slag powder by-produced in the manufacturing process of non-ferrous metals, coal, combustion ash powder such as garbage, gypsum powder, powdered metals, carbon black, activated carbon powder, metals Examples include ceramic powder such as oxides, pigments, and the like, that is, all dust-generating substances that generate dust when solid particulate matter scatters and floats in the air.

The amount of the dust suppressing treatment agent composition used in the present invention to be added to the dust-generating substance depends on the type of the dust-generating substance, particle size distribution, specific gravity (true specific gravity, apparent specific gravity), dust suppressing treatment temperature, compression-shearing action to be applied. It can be appropriately set depending on the degree of dust suppression, the degree of dust suppression of the obtained dust-suppressed product, and the like.
As a guideline for the amount to be added, for example, the dust suppressing treatment composition is preferably 0.001 to 1.0% by mass in terms of the non-melt-flowable TFE copolymer resin solid content with respect to the dust-generating substance. is added in the range of 0.005 to 0.50% by mass, it is possible to suppress dust generated from dust-generating substances.

Furthermore, in the dust-suppressing treatment agent composition of the dust-generating substance used in the present invention, the non-melt-flowable TFE copolymer does not harden firmly even after standing still for a long period of time. Since it has excellent dispersibility (low redispersion sedimentation rate), it is possible to reduce the disposal cost, and it is also preferable from an economic point of view.

Furthermore, by using the dust suppressing treatment agent powder of dust-generating substances obtained by granulating and drying the dust suppressing treatment agent composition of the present invention, hygroscopicity or deliquescence can be improved. Dust-proofing treatment can also be applied to dust-generating substances that dislike moisture. As for the dustproofing method using powder, for example, Japanese Patent Publication No. 52-32877 can be referred to.

EXAMPLES The present invention will be described in more detail below with reference to Examples and Comparative Examples, but the description does not limit the present invention.
In the present invention, each physical property was measured by the following methods.

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

[2] Standard specific gravity (SSG)
Measured according to ASTM D-4894.
A non-melt-flowable TFE copolymer aqueous dispersion obtained by emulsion polymerization or a TFE polymer aqueous dispersion was adjusted to a concentration of 15% by mass using pure water. After that, about 750 ml of the non-melt-flowable TFE copolymer aqueous dispersion or the TFE polymer aqueous dispersion adjusted to the above concentration is placed in a polyethylene container (500 ml volume), and vigorously shaken by hand to agglomerate the solid content. separated. The separated solid was dried at 150° C. for 2 hours. 12.0 g of the dried solid content (resin powder) was placed in a cylindrical mold with a diameter of 2.85 cm and leveled, and after 30 seconds the pressure was gradually increased so that the final pressure reached 350 kg/cm ^{2 .} was held for 2 minutes at a final pressure of The preforms thus obtained (two pieces per sample) were heated in an air oven from 290°C to 380°C at a rate of 2°C/min, and held at 380°C for 30 minutes. After the temperature was lowered to 294°C at a rate of 1/min and held at 294°C for 1 minute, the sample was removed from the air furnace and cooled to room temperature (23±1°C) to obtain 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 taken as the standard specific gravity. In this case, the average value of the standard specific gravities of the two samples was obtained and used as the standard specific gravity.
This standard specific gravity serves as a measure of the average molecular weight, and generally, the lower the standard specific gravity, the larger the molecular weight.

[3-1] Comonomer content ((perfluorobutyl)ethylene (PFBE) content)
0.8±0.050 g of dry solid content (resin powder) obtained from a non-melt-flowable TFE copolymer aqueous dispersion or a TFE polymer aqueous dispersion in the same manner as in [2] above was placed in a cylindrical mold with a diameter of 2.85 cm, smoothed between aluminum foils, and after 30 seconds, the pressure was gradually increased so that the final pressure was 496 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 PFBE contents (% by mass) (two points with PFBE contents of 0% by mass and 0.03% by mass). The infrared spectra of these samples were measured, and the absorbance ratio X was determined by the following formula (3).
Absorbance ratio X = (C - B) / (A - B) (3)
A: 936 cm ^-1 peak height (absorbance)
B: 887 cm ^-1 peak height (absorbance)
C: 875 cm ^-1 peak height (absorbance)
A calibration curve is created from the PFBE content (mass%) of two samples whose PFBE content (mass%) is known and the absorbance ratio X, and the PFBE content (mass%) of the sample is calculated from the absorbance ratio X of the sample. asked.

[3-2] Comonomer content (perfluoropropyl vinyl ether (PPVE) content)
1.75±0.005 g of dry solid content (resin powder) obtained from a non-melt-flowable TFE copolymer aqueous dispersion or a TFE polymer aqueous dispersion in the same manner as in [2] above was placed in a cylindrical mold with a diameter of 2.85 cm and smoothed between aluminum foil, and pressure was applied for 30 seconds, gradually increasing to a final pressure of 1470 kg/cm ² , and this final pressure was maintained. After holding for 2 minutes, a sample 1 for measurement was obtained. Similarly, measurement samples were prepared for resin powders with known PPVE contents (% by mass) (two points with PPVE contents of 0% by mass and 0.75% by mass). The infrared spectra of these samples were measured, and the absorbance ratio and the absorbance ratio _X1 were determined by 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 is created from the PPVE content (mass%) of two samples whose PPVE content (mass%) is known and the absorbance ratio X _{1, and the PPVE content (mass%) of the sample is calculated from the absorbance ratio X 1 of} the sample. ).

[3-3] Comonomer content (hexafluoropropylene (HFP) content)
Sample 1.75 ± 0 of dry solid content (resin powder) obtained from non-melt-flowable TFE copolymer aqueous dispersion or TFE polymer aqueous dispersion by the same method as in [2] above. 0.005 g was placed in a cylindrical mold of 2.85 cm diameter and smoothed between aluminum foil, pressure was applied for 30 seconds, increasing gradually to a final pressure of 1470 kg/cm ² , and this final pressure was applied. This was maintained for 2 minutes to obtain a sample for measurement. Similarly, measurement samples are prepared for resin powders with known HFP contents (% by mass) (three points with HFP contents of 0.06% by mass, 0.08% by mass, and 0.12% by mass). Infrared spectra of these samples were measured, and the absorbance ratio and absorbance ratio _X2 were determined by the following equations (6) and (7).
Absorbance ratio X ₂ = (absorbance ratio of sample/absorbance ratio of known sample) x 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 is created from the HFP content (mass%) and the absorbance ratio X 2 of three samples whose HFP content (mass%) is known, and the HFP content (mass%) of the sample is calculated from the absorbance ratio X ₂ of the sample _. ).

[4] Solid content mass%
Weigh less than 6 g of the non-melt-flowable TFE copolymer aqueous dispersion or the TFE polymer aqueous dispersion into a tared aluminum dish, and add the non-melt-flowable TFE copolymer aqueous dispersion, or The mass of the TFE polymer aqueous dispersion (mass before drying) was weighed (measured to four decimal places). After that, leave it for 2 hours in a dryer at 105 ° C. to remove moisture, bake at a constant temperature of 380 ° C. for 20 minutes and cool to room temperature, then weigh the mass (mass after drying) and use the following formula (8 ) to calculate the solid content mass %.
Solid content mass% = [(mass after drying - tare mass of aluminum pan) / mass before drying] x
100 (8)

[5] Melting point In the same manner as in [2] above, the non-melt-flowable TFE copolymer aqueous dispersion or the dried solid content (resin powder) obtained from the TFE polymer aqueous dispersion is measured. After putting 10.0±0.3 mg in a super clean aluminum sample pan (manufactured by PerkinElmer Japan Co., Ltd.), a cover was put on it, and a standard crimper press was used to seal it to prepare a sample for measurement. The measurement sample was measured using an input-compensated differential scanning calorimeter Diamond DSC (manufactured by PerkinElmer Japan Co., Ltd.), and an empty super clean aluminum sample pan was used as a reference material. The calorific value was measured while warming. As a result of the measurement, the temperature at which the observed endothermic peak was maximum was taken as the melting point of the measurement sample (resin powder).

[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 is placed in a centrifuge tube (manufactured by Corning, 15 ml centrifuge tube). Centrifugation was performed for 30 minutes at a temperature of 20° C. and a rotation speed of 3000 rpm using a centrifuge (manufactured by Kubota Corporation, table top cooling centrifuge 5500, angle rotor RA508). From the centrifuge tube after centrifugation, remove the solid content other than the solid content that has settled at the bottom of the centrifuge tube (liquid portion: supernatant and unsettled solid content), leave the centrifuge tube upside down for 30 minutes, and further remove the liquid portion. Removed and measured the mass (the total of the mass of the centrifuge tube and the mass of the solid content that has settled at the bottom of the centrifuge tube), and the mass obtained by subtracting the mass of the centrifuge tube from there is defined as the solid content sedimentation amount, and 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,
X ₀ : 15 g of the TFE polymer aqueous dispersion shown in Comparative Example 1 was centrifuged with a centrifuge at a temperature of 20°C and a rotation speed of 3000 rpm for 30 minutes, and then solid content other than the solid content that had settled to the bottom of the centrifuge tube. It is the sedimentation ratio (%) of solids indicated by the following formula (10) when (liquid portion: supernatant and unsettled solids) is removed.
X ₁ : 15 g of the non-melt-flowable TFE copolymer aqueous dispersion shown in Examples,
After centrifuging with a centrifuge at a temperature of 20°C and a rotation speed of 3000 rpm for 30 minutes, the solid content other than the solid content that settled at the bottom of the centrifuge tube (liquid portion:
The following formula (10) when removing the supernatant and unsettled solids)
Solid content sedimentation ratio (%) which is the solid content sedimentation ratio (%) indicated by
= (solid content sedimentation amount) / (solid content mass before centrifugation) x 100 (10)

[7] Centrifugation 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 solid content that settled at the bottom of the centrifuge tube was adjusted to 38 kHz. After ultrasonic dispersion for 1 minute, remove the solid content other than the solid content (liquid portion and re-dispersed solid content) that has settled at the bottom of the centrifuge tube, and leave the centrifuge tube upside down for 30 minutes to further remove the liquid portion. Then, measure the mass (the total of the mass of the centrifuge tube and the mass of the solid content that has settled at the bottom of the centrifuge tube), and subtract the mass of the centrifuge tube from it as the solid content sedimentation amount after redispersion. The solid sedimentation ratio after redispersion was calculated from the formula (2′), and the redispersion sedimentation ratio 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 TFE polymer aqueous dispersion shown in Comparative Example 1 was heated to 20°C,
It is the solid content sedimentation ratio (%) shown by the following formula (2') when re-dispersed after centrifuging with a centrifuge at a rotation speed of 3000 rpm for 30 minutes.
X ₃ : 15 g of the non-melt-flowable TFE copolymer aqueous dispersion shown in Examples,
It is the sedimentation ratio (%) of solid content represented by the following formula (2′) when re-dispersed after centrifuging with a centrifuge at a temperature of 20° C. and a rotation speed of 3000 rpm for 30 minutes.
Solid sedimentation ratio after redispersion (%)
= (Solid sedimentation amount after redispersion) / (Solid content mass before centrifugation) x 100
... (2')

[8] Static sedimentation test As shown in Table 2, 15 g of a non-melt-flowable TFE copolymer aqueous dispersion or TFE polymer aqueous dispersion was placed in a centrifuge tube, and after closing the mouth of the centrifuge tube, It was allowed to stand at room temperature for 30 days, 60 days, and 90 days. After standing still for 30 days, 60 days, or 90 days, open the mouth of the centrifuge tube, remove the solid content other than the settled solid content (liquid portion: supernatant and unsettled solid content), and turn the centrifuge tube upside down. Allow to stand for 30 minutes, remove the liquid portion, measure its mass (the total mass of the centrifuge tube and the mass of the solid content that has settled at the bottom of the centrifuge tube), and subtract the mass of the centrifuge tube from it. As the solid content sedimentation amount after placing, the solid content sedimentation ratio was calculated from the following formula (12), and the sedimentation rate was calculated from the following formula (11).

Sedimentation rate=X ₅ /X ₄ ×100 (11)
During the ceremony,
X ₄ : 15 g of the TFE polymer aqueous dispersion shown in Comparative Example 1 was allowed to stand at room temperature for 30 days, 60 days, and 90 days after closing the mouth of the centrifuge tube, and then sedimented. Remove solids other than solids (liquid part: supernatant and unsettled solids), leave the centrifuge tube upside down for 30 minutes, and remove the liquid part. Minute sedimentation ratio (%)
).
X ₅ : 15 g of the non-melt-flowable TFE copolymer aqueous dispersion shown in Examples,
After closing the mouth of the centrifuge tube, leave it at room temperature for 30 days, 60 days, and 90 days. Then, leave the centrifuge tube upside down for 30 minutes to further remove the liquid portion, and then measure the sedimentation amount (mass) of the solid content after standing.
is measured, and is the solid content sedimentation ratio (%) shown by the following formula (12).
Solid content sedimentation ratio (%)
= (Solid content sedimentation amount after standing) / (Solid content mass before standing) x 100
(12)

[9] Static sedimentation redispersion test The mass of the test tube left still in the above [8] is measured, 10 g of pure water is added to the centrifuge tube, and the solid content that has settled at the bottom of the centrifuge tube is measured at 38 kHz. After ultrasonically dispersing for 1 minute, remove the solid content other than the solid content (liquid portion and redispersed solid content) at the bottom of the centrifuge tube, and leave the centrifuge tube upside down for 30 minutes to further remove the liquid portion. Then, measure the mass (the total of the mass of the centrifuge tube and the mass of the solid content that has settled at the bottom of the centrifuge tube), and subtract the mass of the centrifuge tube from that mass as the solid content sedimentation amount after redispersion, using the following formula The sedimentation rate of redispersed solids was calculated from (14), and the sedimentation rate of redispersed solids was calculated from the following formula (13).

Redispersion sedimentation rate=X ₇ /X ₆ ×100 (13)
During the ceremony,
X ₆ : 15 g of the TFE polymer aqueous dispersion shown in Comparative Example 1 was allowed to stand at room temperature for 30 days, 60 days, and 90 days after closing the mouth of the centrifuge tube, and then sedimented. After removing non-solid content (liquid portion: supernatant and unsettled solid content), leaving the centrifuge tube upside down for 30 minutes to further remove the liquid portion, and re-dispersing, the following formula ( 14) is the solid sedimentation ratio (%).
X ₇ : 15 g of the non-melt-flowable TFE copolymer aqueous dispersion shown in Examples,
After closing the mouth of the centrifuge tube, leave it at room temperature for 30 days, 60 days, and 90 days. Then, the centrifuge tube is left upside down for 30 minutes to further remove the liquid portion, and then redispersed according to the following formula (14
) is the solid sedimentation ratio (%).
Solid sedimentation ratio after redispersion (%)
= (Solid sedimentation amount after redispersion) / (Solid content mass before centrifugation) x 100
(14)

[10] Drop dust generation test (drop dust generation amount)
200 g of the sample (dust-suppressed product) is allowed to fall naturally from the top inlet of a cylindrical container with an inner diameter of 39 cm and a height of 59 cm, and the amount of floating dust in the container at a height of 45 cm from the bottom (relative concentration (CPM: Counts per Minute) ) was measured with a scattered light digital dust meter.The amount of floating dust was measured five times continuously for one minute after the sample was added, and the geometric mean value of the values obtained by subtracting the measured value (dark count) before the sample was added. x (CPM) was taken as the “falling dust generation amount” of the sample, and the geometric mean value x was obtained by the following formula (15).
Log x=(1/5)×Σlog(xi−d) (15)
In the formula, xi: individual airborne dust amount, d: dark count.
If the falling dust generation amount (CPM) is 50 or less, the dustproof performance is more excellent, which is more preferable.

(Example 1)
(Polymerization of non-melt-flowable TFE copolymer)
60 g of paraffin wax, 2087 ml of deionized water, fluoromonoether acid (formula C ₃ F ₇ -0 12.03 g of ammonium salt of fluoropolyether acid ( _{C 3 F 7} -O-[CF(CF ₃ )CF ₂ ]n-CF(CF ₃ )COOH). 1.0 g and 0.01 g of polyoxyethylene alkylphenyl ether were charged, and while heating to 80° C., the inside of the system was purged with nitrogen gas three times to remove oxygen, and then evacuated. After that, 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 increase the internal pressure to 1.90-1. The internal temperature was kept at 80° C. while stirring at 110 rpm at 98 MPa.

Next, 100 ml of an aqueous solution of 0.12 g of ammonium persulfate dissolved in 400 ml of water was pumped. After the injection of the ammonium persulfate aqueous solution was completed, TFE was continuously supplied so as to keep the internal pressure at 2.0 MPa. Stirring was stopped when TFE consumption reached 1106.79 g. The gas in the autoclave was released to normal pressure, the pressure was evacuated, and the pressure was returned to normal pressure with nitrogen gas, and then the contents were taken out and the reaction was terminated to obtain a non-melt-flowable TFE copolymer aqueous dispersion. .

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

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

(Comparative example 1)
Regarding the TFE polymer aqueous dispersion (Teflon (registered trademark) PTFE dispersion 312-JR, manufactured by Mitsui Chemours Fluoro Products Co., Ltd.), the particle size (d84) at a cumulative volume percentage of 84%, SSG, PFBE content, solid content The mass and the content of perfluorooctanoic acid and its salts were measured. In addition, a centrifugal sedimentation test and a centrifugal sedimentation redispersion test were conducted. In addition, physical properties were analyzed in the same manner as in Example 1. The results are shown in Table 1 and FIG.

Furthermore, static sedimentation tests and static sedimentation redispersion tests were conducted for Examples 1 and 2 and Comparative Example 1. The results are shown in Table 2 and FIG. In addition, photographs of Example 2 and Comparative Example 1 after standing for 90 days are shown in FIG.

(Drop dust generation test)
(Example 4, Comparative Example 2)
Powdered quicklime containing 95.7% CaO and 1.6% MgO (through a 2.0 mm standard mesh sieve, 1.0 mm standard mesh sieve residue 17.3%, 600 μm standard mesh sieve residue 18.9%, 300 μm standard mesh sieve residue 18.1%, 150 μm standard mesh sieve residue 14.1%, 150 μm standard mesh sieve passage 31.6% powdered quicklime) 1,000 g in volume 5 liter small soil mixer, and while stirring at a rotation speed of 140 rpm, the non-melt-flowable TFE copolymer aqueous dispersion or TFE polymer aqueous dispersion prepared in Example 2 or Comparative Example 1 was added to the solid content mass. A mass equivalent to 0.05 g in terms of conversion (0.005% by mass in solid content mass of the non-melt-flowable TFE copolymer or TFE polymer with respect to quicklime) was weighed, and the non-melt-flowable TFE copolymer aqueous The dispersion or TFE polymer aqueous dispersion was diluted with water so that the total amount of water and water contained in the dispersion was 100 g, and the dispersion in which the composition was dispersed was gradually added.
About 1 minute after the start of charging, steam started to be generated due to the heat of hydration reaction of quicklime, and in about 2 minutes after that, all of the water was used up for the production of slaked lime by hydration of quicklime, and the generation of steam stopped. . Stirring of the mixer was stopped 3 minutes after the start of stirring. When the temperature at this time was measured with a thermometer, it was 107°C. This dust-suppressing quicklime was a mixture of quicklime and slaked lime containing about 30% of slaked lime newly formed by hydration reaction. A falling dust generation test was conducted on the obtained dust-suppressing treated material. Table 3 shows the results.

(Examples 5 and 6, Comparative Examples 3 and 4)
The non-melt-flowable TFE copolymer aqueous dispersion or TFE polymer aqueous dispersion prepared in Example 2 or Comparative Example 1 was added in an amount shown in Table 3 (solid content mass% relative to the dust-generating substance). Weigh the mass, dilute with water so that the total amount of water and water contained in the non-melt-flowable TFE copolymer aqueous dispersion or TFE polymer aqueous dispersion is 100 g, and prepare the composition. A mixture of dust-inhibiting treated quicklime and slaked lime was obtained in the same manner as in Example 4, except that a dispersed dispersion was used. A drop dust generation test was conducted on the obtained dust-suppressing treated material. Table 3 shows the results.

(Comparative Example 5)
A mixture of quicklime and slaked lime obtained in the same manner as in Example 4 except that 100 g of water was used without using a non-melt-flowable TFE copolymer aqueous dispersion or TFE polymer aqueous dispersion. A dust test was performed. Table 3 shows the results.

(Examples 7-13)
(Polymerization of non-melt-flowable TFE copolymer)
60 g of paraffin wax, 2087 ml of deionized water, fluoromonoether acid (formula C ₃ F ₇ -0 12.03 g of ammonium salt of fluoropolyether acid ( _{C 3 F 7} -O-[CF(CF ₃ )CF ₂ ]n-CF(CF ₃ )COOH). 1.0 g and 0.01 g of polyoxyethylene alkylphenyl ether were charged, and while heating to 80° C., the inside of the system was purged with nitrogen gas three times to remove oxygen, and then evacuated. The comonomer (HFP or PPVE) was then pumped in the amounts listed in Table 4. Thereafter, tetrafluoroethylene (TFE) was supplied to adjust the internal pressure to 1.90-1.98 MPa, and the internal temperature was kept at 80° C. while stirring at 110 rpm.

Next, 100 ml of an aqueous solution of 0.12 g of ammonium persulfate dissolved in 400 ml of water was pumped. After the injection of the ammonium persulfate aqueous solution was completed, TFE was continuously supplied so as to keep the internal pressure at 2.0 MPa. Stirring was stopped when TFE consumption reached 1106.79 g. The gas in the autoclave was released to normal pressure, the pressure was evacuated, and the pressure was returned to normal pressure with nitrogen gas, and then the contents were taken out and the reaction was terminated to obtain a non-melt-flowable TFE copolymer aqueous dispersion. .

For the resulting non-melt-flowable TFE copolymer aqueous dispersion, particle size (d84) at cumulative volume percentage of 84%, SSG, PFBE content, solid content mass, melting point, and perfluorooctanoic acid and its salts amount was measured. In addition, a centrifugal sedimentation test and a centrifugal sedimentation redispersion test were conducted. Table 4 shows the results.

(Examples 14, 15, 21, 23, 24, 29, 30, 32-35)
The dust-generating substances shown below and the non-melt-flowable TFE copolymer aqueous dispersions prepared in Examples 7 to 13 were added in the amounts shown in Table 5 or Table 6 (mass% of solid content relative to the dust-generating substance). Weigh a mass equivalent to , and use a dispersion diluted with water so that the total amount of water and water contained in the non-melt-flowable TFE copolymer aqueous dispersion is 100 g. A dust-suppressing treatment was obtained. A drop dust generation test was conducted on the obtained dust-suppressing treated material. The results are shown in Table 5 or Table 6.

(Examples 16-20, 22, 25-28, 31)
The dust-generating substances shown below and the non-melt-flowable TFE copolymer aqueous dispersions prepared in Examples 7 to 13 were added in the amounts shown in Table 5 or Table 6 (mass% of solid content relative to the dust-generating substance). Weigh a mass equivalent to , and use a dispersion diluted with water so that the total amount of water and water contained in the non-melt-flowable TFE copolymer aqueous dispersion is 35 g. A dust-suppressing treatment was obtained. A drop dust generation test was conducted on the obtained dust-suppressing treated material. The results are shown in Table 5 or Table 6.

<Dust-generating substances>
・Powder quicklime (containing 96.0% CaO and 0.9% MgO)
(Through 2.0 mm standard mesh sieve, 1.0 mm standard mesh sieve residue 0.18%, 600 μm standard mesh sieve residue 2.48%, 300 μm standard mesh sieve residue 20.44%, 150 μm standard mesh sieve residue 20.58%, 150 μm standard mesh sieve passage 56.32% powder quicklime)
Dustproof treatment of powdered quicklime (Examples 14, 15, 21, 23, 24, 29, 30, 32-35):
Weigh 1000 g of powdered quicklime in a mortar mixer container, set the container in the mortar mixer, stir at a low speed, and add the dispersion diluted with water (non-melt fluidity corresponding to the addition amount shown in Table 5 or Table 6) (mass of TFE copolymer + 100 g of water) was put into a mortar mixer, and stirring of the mixer was stopped after 3 minutes from the start of stirring. After that, the quicklime in the mortar mixer was transferred to an enamel tray and left to cool for about 5 minutes to obtain a dust-suppressed product.

Ordinary Portland cement, (64.3% CaO and 1.1% MgO _{, 20.5% SiO2, 5.1% Al2O3 , 3.1 % Fe2O3} and _SO3 containing 2.0%)
(2.0 mm standard mesh sieve, 1.0 mm standard mesh sieve, 600 μm standard mesh sieve, 300 μm standard mesh sieve, 150 μm standard mesh sieve residue 0.00 22%, 99.78% ordinary Portland cement passing through a standard mesh sieve of 150 μm)
Dustproof treatment of a 9:1 mixture of ordinary Portland cement (hereinafter referred to as cement) and the powdered quicklime (Examples 16, 22, 25, 31):
450 g×2 of cement was weighed, spread evenly on an enamel tray, and heated at 105° C. for one day and night. 100 g of powdered quicklime was weighed into a container of a mortar mixer, and the dispersion diluted with water (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. The mixture was put into a mixer and stirred at a low speed for 1 minute to obtain a material A. 450 g 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. 450 g of cement heated to 105° C. was added to the obtained material B, and the mixture was stirred with a mortar mixer for 3 minutes to obtain a dust-suppressing product.

Anhydrous gypsum (2.0 mm standard mesh sieve all through, 1.0 mm standard mesh sieve all through, 600 μm standard mesh sieve residue 0.13%, 300 μm standard mesh sieve residue 0.22%, Anhydrous gypsum with a 150 μm standard mesh sieve residue of 11.33% and a 150 μm standard mesh sieve passage of 88.31%)
Dustproof treatment of anhydrite (Examples 17 and 26):
500 g×2 of anhydrous gypsum were weighed, spread evenly on an enamel tray, and heated at 105° C. for one day. 500 g of heated anhydride gypsum was weighed into a container of a mortar mixer, and the dispersion diluted with water (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 ) is put into a mortar mixer and stirred at a low speed for 1 minute, 500 g of anhydride gypsum heated to 105 ° C. is added and stirred for 3 minutes, spread evenly on an enamel tray, and heated at 105 ° C. for 1 hour. A mixture was obtained. About 1 kg of the mixture was placed in a mortar and stirred with a pestle for 9 minutes to obtain a dust-suppressing treatment.

・ Ground granulated blast furnace slag (2.0 mm standard mesh sieve through, 1.0 mm standard mesh sieve through, 600 μm standard mesh sieve residue 0.02%, 300 μm standard mesh sieve residue 0 0.06%, granulated blast furnace slag with a 150 μm standard mesh sieve residue of 0.31% and a 150 μm standard mesh sieve passage of 99.61%)
Dust-proof treatment of ground granulated blast furnace slag (Examples 18 and 27):
A dust-suppressing treated product was obtained in the same manner as the dust-proofing treatment of anhydrous gypsum, except that granulated granulated blast furnace slag was used.

Dolomite (2.0 mm standard mesh sieve through, 1.0 mm standard mesh sieve residue 0.06%, 600 μm standard mesh sieve residue 0.50%, 300 μm standard mesh sieve residue 3.44 %, Dolomite with 150 μm standard mesh sieve residue 8.20%, 150 μm standard mesh sieve passage 87.79%)
Dustproof treatment of dolomite (Examples 19 and 28):
500 g×2 of dolomite was weighed, spread evenly on an enamel tray, and heated at 105° C. for one day and night. 500 g of heated dolomite was weighed into a container of a mortar mixer, and the dispersion diluted with the above water (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). is put into a mortar mixer and stirred at a low speed for 1 minute, 500 g of dolomite heated to 105 ° C. is added and stirred for 3 minutes, spread evenly on an enamel tray, heated at 105 ° C. for 1 hour to make the mixture Obtained. About 1 kg of the mixture was placed in a mortar mixer and stirred for 3 minutes to obtain a dust-suppressing product.

・ Lignite powder (2.0 mm standard mesh sieve, 1.0 mm standard mesh sieve, 600 μm standard mesh sieve, 300 μm standard mesh sieve residue 0.02%, 150 μm standard Lignite powder with a mesh sieve residue of 33.03% and a standard mesh sieve passage of 66.95% of 150 μm)
Dustproof treatment of lignite powder (Example 20):
500 g of lignite powder (hygroscopic dust-generating powder) was weighed, spread evenly on an enamel tray, and heated at 105° C. for one day and night. Pure water is added so that the solid content of the aqueous dispersion of Example 7 becomes 15%, and the mixture is put into a granulation tank equipped with a stirrer, and then stirred at 600 to 700 rpm until the powder precipitates. Stirring was continued for 3 to 5 minutes, the precipitated powder was collected with a mesh and separated from water, dried in an oven at 150 ° C. for 2 to 15 hours until the water was gone, and allowed to cool to room temperature. A powder consisting of an aqueous dispersion was obtained. 5 g of the obtained powder and about 1/4 of the heated lignite powder were placed in a mortar and then slowly mixed with a pestle. Further, lignite powder was added in 3 portions of 1/4 each and mixed, 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 treatment.

The dust suppression treatment method of the present invention is used in the fields of building materials, soil stabilizers, solidifying materials, fertilizers, landfill disposal of incineration ash or hazardous substances, explosion-proof fields, cosmetics fields, fillers for various plastics, etc. , it is suitably used for obtaining a dust-suppressing treated product of the dust-generating substance by subjecting the dust-generating substance to dust-suppressing treatment.

Claims (14)

1. Perfluorooctanoic acid and a salt thereof in the aqueous dispersion comprising an aqueous dispersion of a non-melt-flowable tetrafluoroethylene copolymer, wherein the copolymer has a redispersion sedimentation rate represented by the following formula of 60% or less. content is less than 10 ppb, the dust suppressing treatment composition is mixed with a dust-generating substance, and the mixture is subjected to compression-shearing action at a temperature of 20 to 200 ° C. A dust suppression treatment method for a dust-generating substance, characterized in that the tetrafluoroethylene copolymer is fibrillated to suppress the generation of dust by the dust-generating substance.
   Redispersion sedimentation rate (%) = X ₃ /X ₂ × 100
   During the ceremony,
   _X2 : 15 g of an aqueous dispersion containing less than 10 ppb of perfluorooctanoic acid and its salt relative to the mass of the aqueous dispersion and containing a tetrafluoroethylene polymer having the same concentration as the copolymer was heated to 20°C. , Centrifuge for 30 minutes at a rotation speed of 3000 rpm, and then re-dispersed, solid sedimentation ratio (%) after re-dispersion shown by the following formula
   X ₃ : 15 g of the aqueous copolymer dispersion was heated to 20°C and rotated at 3
   After centrifuging with a centrifuge at 000 rpm for 30 minutes and then re-dispersing, the solid sedimentation ratio (%) after re-dispersion is shown by the following formula.
   Solid sedimentation ratio after redispersion (%)
   = (Solid sedimentation amount after redispersion) / (Solid content mass before centrifugation)
   ×100
2. The dust suppression treatment method for dust-generating substances according to claim 1, wherein the content of the perfluorooctanoic acid and its salt in the aqueous dispersion is less than 5 ppb.
3. 3. The dust suppression treatment method for dust-generating substances according to claim 1 or 2, wherein the particle size (d84) at a cumulative volume percentage of 84% of the copolymer is 250 nm or less.
4. The non-melt-flowable tetrafluoroethylene copolymer is a non-melt of tetrafluoroethylene and at least one comonomer selected from (perfluoroalkyl)ethylene, perfluoro(alkyl vinyl ether), and hexafluoropropylene. 2. The method for suppressing dust of a dust-generating substance according to claim 1, wherein the dust-generating substance is a fluid copolymer.
5. The dust suppression treatment method for dust-generating substances according to claim 4, wherein the perfluoroalkyl group in the (perfluoroalkyl)ethylene is a perfluoroalkyl group having 1 to 10 carbon atoms.
6. The (perfluoroalkyl)ethylene is at least one selected from (perfluoroethyl)ethylene, (perfluorobutyl)ethylene, (perfluorohexyl)ethylene, and (perfluorooctyl)ethylene, or 6. The dust suppression treatment method for the dust-generating substance according to 5 above.
7. The dust suppression treatment method for dust-generating substances according to claim 4, wherein the perfluoroalkyl group in the perfluoro(alkyl vinyl ether) is a perfluoroalkyl group having 1 to 10 carbon atoms.
8. 8. The dust-generating substance according to claim 7, wherein the perfluoro(alkyl vinyl ether) is at least one selected from perfluoro(methyl vinyl ether), perfluoro(ethyl vinyl ether), and perfluoro(propyl vinyl ether). Dust suppression treatment method.
9. The dust suppression treatment method for dust-generating substances according to claim 4, wherein the comonomer is contained in an amount of 0.01 to 1.00% by mass with respect to tetrafluoroethylene.
10. The dust suppression treatment method for dust-generating substances according to claim 4, wherein the comonomer is contained in an amount of 0.01 to 0.50% by mass with respect to tetrafluoroethylene.
11. The method for controlling dust of dust-generating substances according to claim 1 or 2, wherein the copolymer is contained in the dust controlling agent composition in an amount of 10 to 80% by mass.
12. The dust suppression treatment method for dust-generating substances according to claim 1 or 2, wherein the specific gravity (SSG) of the copolymer is 2.27 or less.
13. The dust suppression treatment method for a dust-generating substance according to claim 1 or 2, wherein the dust-generating substance is a dust-generating powdery substance.
14. The method for controlling dust of dust-generating substances according to claim 1 or 2, wherein the dust controlling agent powder is obtained by granulating and then drying the dust controlling agent composition.

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