JPH09328340A - Dustproof treatment of dusting powder - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for carrying out dustproof treatment of dusting powder, by which excellent dustproof effect is exhibited by the same amount as the amount of a dustproof treating agent consisting essentially of fibrillated polytetrafluoroethylene(PTFE) or equivalent dustproof effect is exhibited by a smaller amount of the dustproof treating agent. SOLUTION: In carrying out dustproof treatment by catching dustproof powder by fibril of fibrillated PTFE, a substance evolving reaction heat by hydration reaction is mixed with fibrillated PTFE and water and stirred and temperature of the mixture is raised by hydration reaction heat. PTFE is fibrillated by compression and shearing action in mixing under stirring and dustproof powder to be treated is divided into at least one or more portions while leaving residual heat and added to the fibrillated PTFE and the powder is mixed with the PTFE under stirring.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a fibrillating polytetrafluoroethylene resin (hereinafter referred to as PTFE).
The present invention relates to a dustproof treatment method for dusting powders.

[0002]

2. Description of the Related Art A method of mixing PTFE with a powdery substance and subjecting the mixture to compression-shearing at a temperature of about 20 to 200 ° C. to fibrillate the PTFE to suppress the generation of dust from the powdery substance is particularly known. It is known from JP-B-52-32877. The PTFE disclosed here is
The composition is Teflon (registered trademark) 6 or Teflon (registered trademark) 3 which is a fine powder or an emulsion in the form of a homopolymer of tetrafluoroethylene.
0, and a modified polymer of tetrafluoroethylene in the form of Teflon (registered trademark) 6C or Teflon (registered trademark) 64, which is also a fine powder or emulsion. After that, the brand name "Teflon (registered trademark) K-10" was used as a brand for dust control.
(Powder PTFE) and "Teflon (registered trademark) K-2"
“0” (PTFE emulsion) has been developed and is commercially available.

[0003] PTFE fibrillates due to the compression-shearing action during mixing and stirring, but since the fibrillation rate at room temperature is slow, it is necessary to provide the compression-shearing action by stirring at elevated temperature, for example, at 50 ° C or higher. Is preferred. Previously, the present inventors have found that PTFE fibrils are produced with high efficiency by utilizing the heat of hydration of quicklime or light burned dolomite as a heat source, and a substance that emits reaction heat by a hydration reaction in advance, for example, powdered quicklime. A predetermined amount of water-dispersed PTF
E was added, the temperature was raised to about 50 ° C., and the mixture was stirred, so that a partially-hydrated quicklime powder was trapped by partially fibrillated PTFE, and a dust-preventing agent invented by itself was invented. When this dustproofing agent is mixed with water in a dusting powder and stirred, unhydrated quicklime powder and the like hydrate to generate heat, and fibrillation of PTFE further progresses to cause dusting powder. Dustproof.

This dustproofing agent is sufficiently practical in the field of agriculture such as soil improving material, and in the field of civil engineering such as solidifying material and ground improving material. However, when it is necessary to maintain the strength of Portland cement or the like, the amount of the dustproofing agent containing lime or the like should be minimized. Also, from the viewpoint of dustproof treatment cost, it is better to use as little as possible.

[0005]

DISCLOSURE OF THE INVENTION The present invention shows a better dustproofing effect with the same amount of the dustproofing agent mainly composed of fibrillating PTFE, or an equivalent dustproofing agent by using a smaller amount of the dustproofing agent. It is an object of the present invention to provide a dustproof treatment method for dusting powder that exhibits an effect.

[0006]

A method for dust-proofing dust-generating powder according to the present invention is a method for dust-proofing a dust-generating powder by capturing it with fibril-forming polytetrafluoroethylene resin fibrils. , A material that generates heat of reaction by hydration reaction is mixed with fibrillating polytetrafluoroethylene resin and water and stirred, and the temperature of the mixture is raised by heat of hydration reaction, and the above polytetrafluoroethylene resin is mixed and stirred. It is characterized in that it is fibrillated by compression-shearing action at that time, and the dusting powder to be treated is added at least twice or more and mixed and stirred while having residual heat.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION As the PTFE, the fibrillating PTFE mentioned above can be used. The PTFE fine powder and water may be added and used, or the PTFE aqueous emulsion or its diluted solution may be used. Fibrillable PTFE particles are described in US Pat. No. 2,559,7.
No. 52, an emulsion polymerization method, that is, press-fitting and polymerization in an aqueous medium containing a water-soluble polymerization initiator of tetrafluoroethylene and an anionic surfactant having a fluoroalkyl group as a hydrophobic group as an emulsion stabilizer. To produce an aqueous emulsion.

As the substance that generates reaction heat by the hydration reaction, one or both of quick lime and light burned dolomite are preferably used. Water may be added so that the dusting powder to be treated has a temperature of about 50 ° C. or higher, but in order to minimize the inclusion of lime in the product, the heat of hydration is used to the maximum. In addition, in consideration of the evaporation loss, it is preferable to add a sufficient amount to completely hydrate the substance that generates reaction heat by the hydration reaction.

The dusting powder is added and mixed at least twice, for example, twice or three times. The addition amount in each time may be the same (equal distribution) or may be different in each time (disproportionation), and may be appropriately determined based on the preliminary test results. If the stirring time is too short, PTFE
Is not sufficiently fibrillated and the dustproof effect is inferior, and if the stirring time is too long, the generated fibrils are fractured and the dustproofing effect is reduced, so it is preferable to determine the optimum stirring time based on the preliminary test results.

The present invention will be specifically described based on the following examples, but the present invention is not limited to the following examples.

[0011]

Example 1 3.06 kg of quicklime passing through a 5.0 mm sieve
(Equivalent to 5% by weight with respect to the total amount of quick lime + cement) was put into a high blender type TM-55 (kneading capacity 55 L, peripheral speed 0.72 m / sec) manufactured by Taiheiyo Kiko Co., Ltd., and 18.36 g of fibrillating PTFE ( A liquid in which 1.24 kg of water (corresponding to 0.03% by weight with respect to the total amount of quicklime + cement) was dispersed in water (corresponding to 2.0% by weight with respect to the total amount of quicklime + cement) was added all at once to prepare a masterbatch. Temperature is 1
It was 30 ° C. 1 minute and 30 seconds after adding the fibrillating PTFE aqueous dispersion to the quick lime, 19.38 kg of Portland cement was added, and stirring was continued, and after 3 minutes and 30 seconds, another 19.38 kg of Portland cement was added and 4 minutes and 30 minutes. The remaining 19.38 kg of Portland cement was added after 2 seconds, the stirring was continued as it was, and the stirring was stopped after 6 minutes 00 seconds had elapsed from the start of hydration of the quick lime.
g was obtained. A sample was taken here. Similarly, from the start of lime hydration, 8 minutes 00 seconds, 10 minutes 00 seconds, 12 minutes 00 seconds,
Alternatively, after 15:00 minutes, the mixer was stopped and a sample was taken. The dustproof performance of these samples was measured by the following evaluation method. Table 1 shows the measurement results.

[0012]

[Test method] A 200 g sample is naturally dropped from the top inlet of a cylindrical container with an inner diameter of 39 cm and a height of 69 cm, and the amount of suspended dust in the container at a position 45 cm above the bottom (relative concentration is
untper minute (cpm) was measured with a scattered light type digital dust meter. The specifications of the digital dust meter are “a device that conforms to the relative densitometer shown in Article 2, Paragraph 2 of the Enforcement Regulations of the Working Environment Measurement Act. The amount of suspended dust is measured continuously for 1 minute after the sample is dropped. The geometric mean value of the values obtained by subtracting the measured value (dark count) before the sample was added was defined as the "falling dust amount" of the sample. The geometric mean value x is logx = 1/5 · Σ
represented by log (x ₀ -d). However, x ₀ : individual measured value, d: dark count.

[0013]

[Table 1]

[0014]

[Example 2] As in Example 1, a total of 58,14 kg of Portland cement was added in two times (two steps). The ratio of the first and second Portland cement inputs was 1: 1. Fibrillating PTFE on quicklime
1 minute and 30 seconds after the start of adding the water dispersion (starting hydration of quick lime), the first Portland cement was added and 3
Table 2 shows the result of measuring the dust generation amount of the sample in which the second Portland cement was added all at once after 00 minutes and stirred for a predetermined time.

[0015]

[Table 2]

[0016]

[Example 3] As in Example 1, a total of 58,14 kg of Portland cement was added in two times (two-stage injection). The ratio of the first and second Portland cement inputs was 1: 2. Fibrillating PTFE on quicklime
1 minute and 30 seconds after the start of adding the water dispersion (starting hydration of quick lime), the first Portland cement was added and 3
Table 3 shows the results of measuring the dust generation amount of the sample in which the second Portland cement was added all at once after 00 minutes and stirred for a predetermined time.

[0017]

[Table 3]

[0018]

[Example 4] In the same manner as in Example 1, a total of 58,14 kg of Portland cement was added in two times (two-stage injection). The ratio of the first and second Portland cement inputs was set to 1: 4. Fibrillating PTFE on quicklime
1 minute 3 from the start of adding the aqueous dispersion (starting hydration of quicklime)
Table 4 shows the results of measuring the dust generation amount of the sample, which was charged the first Portland cement after 0 seconds, and then charged the second Portland cement at once after 3 minutes 00 seconds and stirred for a predetermined time.

[0019]

[Table 4]

[0020]

Comparative Example 1 In the same manner as in Example 1, 3.06 kg of quick lime that passed through a 5.0 mm sieve was added to fibrillable PTFE 18.
Fibrillating PTF was added to quicklime in a masterbatch produced by adding a liquid in which 36 g was dispersed in 1.224 kg of fresh water.
Table 5 shows the results of measuring the dust generation amount of the sample in which 58.14 kg of Portland cement was charged all at once after 1 minute 30 seconds from the start of the addition of the E water dispersion (the start of hydration of quicklime) and the mixture was stirred for a predetermined time.

[0021]

[Table 5]

In Examples 1 to 4 and Comparative Example 1, Table 6 shows the case where the amount of generated dust was the smallest. Compared to Comparative Example 1 in which Portland cement was added all at once, the amount of dust generated in each of the examples in which the addition was divided was remarkably reduced.

[0023]

[Table 6]

[0024]

Example 5 3.06 kg of light-burnt dolomite crushed to pass through a 2.0 mm sieve was put into the same blender used in Example 1, and the same fibrillating PTFE 1 as in Example 1 was placed.
A liquid obtained by dispersing 8.36 g in 1.224 kg of fresh water was added under stirring by a mixer, and a hydration reaction was performed to prepare a masterbatch. Fly ash generated from a thermal power plant was added for 19.38 minutes, 2 minutes 30 seconds, 3 minutes 00 seconds, and 4 minutes 30 seconds after the fibrillating PTFE aqueous dispersion was added.
It was charged in 3 batches of kg (the same weight as in Example 1).
Continue stirring the mixture as it is, 6 minutes 00 seconds, 8 minutes 00 seconds, 10 minutes 00 seconds, 12 minutes 00 seconds, and 15 minutes 00.
Samples were taken after 2 seconds and the dustproof performance was measured.

[0025]

[Table 7]

[0026]

EFFECTS OF THE INVENTION When a certain amount of fibrillating PTFE and a substance that generates reaction heat due to a hydration reaction are used, the dusting powder to be treated should be added at least twice and mixed and stirred. Shows a more excellent dustproof effect. Therefore, it is expected that even if a smaller amount of the dustproofing agent is used, the same dustproofing effect is exhibited.

Front page continuation (72) Hiroshi Miyaji 925-4 Nishikawata-cho, Utsunomiya-shi, Tochigi Prefecture (72) Tetsuya Shimoda 1397-3 Hatsawa-cho, Hachioji-shi, Tokyo (72) Kazuhiro Gomachi Fujishiro, Kitasoma-gun, Ibaraki Prefecture Machi Kofudai 1-4-6 (72) Inventor Masatsune Ogura 1-16-11 Arai, Ichikawa City, Chiba Prefecture (72) Inventor Shizuo Chiba 10-5 Ishimachi Shinmachi, Shimizu City Shizuoka Prefecture

Claims (2)

[Claims] 1. A fibrillating polytetrafluoroethylene resin is used as a substance which generates heat of reaction due to a hydration reaction in capturing dust-preventing treatment by capturing dust-generating powder with fibrils of fibrillating polytetrafluoroethylene resin. And water are mixed and stirred, and the temperature of the mixture is raised by the heat of hydration reaction, and at the same time, the polytetrafluoroethylene resin is fibrillated by the compression-shear action at the time of mixing and stirring, and the treatment is carried out while there is residual heat. A dust-proof treatment method for dusting powder, characterized in that the dusting powder to be added is added at least twice or more and mixed and stirred. 2. A substance which generates reaction heat by a hydration reaction,
The dustproof treatment method for dusting powder according to claim 1, wherein either one or both of quick lime and light burned dolomite are used.