Method to prevent dust generation and / or moisture increase of open-air deposits

Abstract

To provide a method to prevent dust generation and / or moisture increase of open-air deposits, which can increase the film strength of a coating film that covers open-air deposit particles and reliably prevent moisture increase in the open-air deposits.SOLUTION: In a method to prevent dust generation and / or moisture increase of open-air deposits, O / W type emulsion containing an acrylic resin and a polyvinyl alcohol resin is dispersed on the open-air deposits.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to a method for preventing dust generation and / or moisture increase in open-air piles. [Background technology]

[0002] In steelworks, power plants, paper and pulp factories, etc., powders such as coal, iron ore, slag, dust, chips, wood chips, sludge paper, etc. are piled up in the open. Dust is generated from the piled up powder, which is an environmental problem. Heavy rains can also cause landslides and coal drift (a phenomenon in which piled up coal drifts and collapses due to an increase in the moisture content of coal, which becomes a slurry). Rainwater from rainfall also penetrates the powder, increasing its moisture content. The increase in the moisture content of piled up powder requires extra energy to evaporate the moisture in the powder when it is used as fuel, which leads to large economic losses and an increase in CO2 emissions. In addition, if the piled up powder is coking coal, it has various adverse effects on the coke manufacturing process. Therefore, there is a need for technology to suppress the increase in moisture content in piled powder.

[0003] Patent Document 1 discloses the use of an acrylic emulsion resin as a hydrophobic treatment agent for open-air piled sediments. By spraying, applying or kneading the hydrophobic treatment agent onto the sediments, hydrophobic portions are formed on the surfaces of the sediment particles. Patent Document 2 discloses spraying an emulsion resin solution having a polymer particle size of 0.3 to 3 μm with a standard deviation of 0.2 μm or more onto piled up sediments. By using an emulsion resin solution having a large polymer particle size and a wide particle size distribution, a coating film that is thick, strong, and crack-resistant is formed on the sediments, preventing dust generation or moisture rise in the piled up sediments. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Special Publication No. 01-38723 [Patent Document 2] JP 2013-203525 A Summary of the Invention [Problem to be solved by the invention]

[0005] The hydrophobizing agent described in Patent Document 1 has a problem in that the film strength is weak and easily broken, causing the film to crack and allowing rainwater, etc. to penetrate. Moreover, even with the method described in Patent Document 2, the strength of the film was insufficient, and cracks sometimes occurred in the film. The present invention aims to provide a method for preventing dust generation and / or moisture increase in open-air deposits, which can increase the film strength of a coating film that covers open-air deposit particles with a coating agent and reliably prevent moisture increase in open-air deposits. [Means for solving the problem]

[0006] As a result of intensive research, the present inventors have found that an emulsion containing an acrylic resin and a polyvinyl alcohol resin can improve the strength of a coating film and reliably prevent an increase in moisture content in piled up deposits. The present invention is based on this finding.

[0007] That is, the present invention provides the following [1] and [2]. [1] A method for preventing dust generation and / or moisture increase in open-air piles, comprising spraying an O / W type emulsion containing an acrylic resin and a polyvinyl alcohol resin onto the piles. [2] A method for preventing dust generation and / or moisture increase in open-air deposits described in [1] above, wherein the acrylic resin is a styrene-acrylic resin and / or a vinyl acetate acrylic resin. Effect of the Invention

[0008] According to the present invention, it is possible to provide a method for preventing dust generation and / or moisture increase in open-air deposits, which can increase the film strength of the coating film that covers open-air deposit particles with a coating agent and reliably prevent the moisture increase in open-air deposits. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] The method for preventing dust generation and / or moisture increase in open-air piles according to the present invention will be described below. In this specification, "(meth)acrylic" means acrylic and methacrylic. In this specification, the term "solid content" refers to components excluding the dispersion medium.

[0010] [Coating material for open-air deposits] The coating agent for piled up deposits used in the present invention is an O / W type emulsion containing an acrylic resin and a polyvinyl alcohol (hereinafter sometimes referred to as "PVA") resin. The coating agent contains PVA resin in addition to acrylic resin, which improves the film strength compared to when it does not contain PVA resin, and can reliably prevent moisture increase in piled up sediments. The reason for this is unclear, but it is presumed to be as follows. When a conventional coating agent that contains acrylic resin but not PVA resin is added to open-air sediments, a coating layer made of acrylic resin is formed on the surface of the sediment particles. However, the coating layer has low film strength, and it is thought that the film cracks and rainwater etc. can penetrate. On the other hand, since the coating agent according to the present invention contains both acrylic resin and PVA resin, when it is added to open-air deposits, a coating layer made of acrylic resin is formed on the surface of the deposit particles, and a protective layer made of PVA resin is formed on the coating layer made of acrylic resin. Furthermore, the acrylic resin and the PVA resin are firmly fused together, which increases the strength of the film and makes it less likely to crack, thereby preventing the penetration of rainwater, etc.

[0011] <Acrylic resin> The acrylic resin is a polymer of a monomer containing one or more selected from the group consisting of (meth)acrylic acid and its esters. The acrylic resin may be a polymer of one or more monomers selected from the group consisting of (meth)acrylic acid and esters thereof, or may be a polymer of one or more monomers selected from the group consisting of (meth)acrylic acid and esters thereof and one or more other monomers.

[0012] The acrylic resin is preferably a styrene acrylic resin and / or a vinyl acetate acrylic resin.

[0013] [Styrene acrylic resin] The styrene-acrylic resin refers to a polymer of monomers including a styrene-based monomer and one or more selected from the group consisting of (meth)acrylic acid and (meth)acrylic acid esters.

[0014] (styrene monomer) Examples of the styrene-based monomer include styrene and styrene derivatives such as α-methylstyrene. The styrene-based monomer is preferably styrene.

[0015] ((Meth)acrylic acid and (meth)acrylic acid esters) (Meth)acrylic acid means acrylic acid and methacrylic acid. Examples of the (meth)acrylic acid ester include (meth)acrylic acid alkyl esters having no particular functional group or cyclic structure, (meth)acrylic acid esters having a hydroxyl group, (meth)acrylic acid esters having a glycidyl group, (meth)acrylic acid esters having an oxyalkylene group, (meth)acrylic acid esters having an alicyclic structure, and (meth)acrylic acid esters having an aromatic ring.

[0016] Examples of (meth)acrylic acid alkyl esters having no particular functional group or cyclic structure include methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, isopropyl (meth)acrylate, butyl (meth)acrylate, isobutyl (meth)acrylate, s-butyl (meth)acrylate, t-butyl (meth)acrylate, pentyl (meth)acrylate, neopentyl (meth)acrylate, hexyl (meth)acrylate, and the like. acrylate, 3-pentyl (meth)acrylate, hexyl (meth)acrylate, 2-ethylbutyl (meth)acrylate, heptyl (meth)acrylate, 2-heptyl (meth)acrylate, octyl (meth)acrylate, 2-octyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, nonyl (meth)acrylate, decyl (meth)acrylate, undecyl (meth)acrylate, dodecyl (meth)acrylate, etc. Among these, from the viewpoint of water resistance and stability over time, butyl (meth)acrylate, isobutyl (meth)acrylate, t-butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, dodecyl (meth)acrylate are preferred.

[0017] Examples of (meth)acrylic acid esters having a hydroxyl group include 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, glycerol mono(meth)acrylate, N-(2-hydroxyethyl)(meth)acrylamide, and allyl alcohol.

[0018] Examples of the (meth)acrylic acid ester having a glycidyl group include glycidyl (meth)acrylate and 4-hydroxybutyl (meth)acrylate glycidyl ether.

[0019] Examples of (meth)acrylic acid esters having an oxyalkylene group include diethylene glycol mono(meth)acrylate, polyethylene glycol mono(meth)acrylate, polyethylene glycol / polypropylene glycol mono(meth)acrylate, methoxydiethylene glycol mono(meth)acrylate, methoxypolyethylene glycol mono(meth)acrylate, phenoxydiethylene glycol mono(meth)acrylate, phenoxypolyethylene glycol mono(meth)acrylate, ethylene glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate, polyethylene glycol di(meth)acrylate, and the like.

[0020] An example of the (meth)acrylic acid ester having an alicyclic structure is cyclohexyl (meth)acrylate. An example of the (meth)acrylic acid ester having an aromatic ring is benzyl (meth)acrylate.

[0021] (Other Monomers) The raw material monomers for the styrene-acrylic resin may or may not contain monomers other than those mentioned above. Examples of other monomers include amide group-containing monomers, vinyl acetate, and other reactive functional group-containing monomers.

[0022] Examples of amide group-containing monomers include N-vinylacetamide, (meth)acrylamide, diacetone (meth)acrylamide, N-methyl (meth)acrylamide, N,N-dimethyl (meth)acrylamide, N-ethyl (meth)acrylamide, N,N-diethyl (meth)acrylamide, N-isopropyl (meth)acrylamide, and N-butyl (meth)acrylamide.

[0023] (Mixing ratio) The amount of the styrene-based monomer in the total amount of raw material monomers of the styrene-acrylic resin is preferably 5 to 70 mass%, more preferably 10 to 60 mass%, and even more preferably 10 to 50 mass%, and may be 20 to 50 mass%, or may be 35 to 45 mass%. The amount of the acrylic monomer in the total amount of raw material monomers of the styrene-acrylic resin is preferably 30 to 95 mass%, more preferably 40 to 90 mass%, and even more preferably 50 to 90 mass%, and may be 50 to 80 mass%, or may be 55 to 65 mass%. The total amount of the styrene-based monomer and the acrylic monomer in the total amount of the raw material monomers of the styrene-acrylic resin is preferably 80 to 100 mass%, more preferably 90 to 100 mass%, still more preferably 95 to 100 mass%, and may be 100 mass%.

[0024] [Vinyl acetate acrylic resin] The vinyl acetate acrylic resin refers to a polymer of monomers containing vinyl acetate and one or more selected from the group consisting of (meth)acrylic acid and (meth)acrylic acid esters.

[0025] ((Meth)acrylic acid and (meth)acrylic acid esters) The types of (meth)acrylic acid and (meth)acrylic acid esters are the same as those described above for the styrene-acrylic resin.

[0026] (Other Monomers) The raw material monomers for the vinyl acetate acrylic resin may or may not contain monomers other than those mentioned above. The types of other monomers are the same as those described above for the styrene-acrylic resin.

[0027] (Mixing ratio) The amount of vinyl acetate in the total amount of raw material monomers for the vinyl acetate acrylic resin is preferably 10 to 95 mass%, more preferably 15 to 90 mass%, even more preferably 20 to 90 mass%, and still more preferably 40 to 90 mass%, or may be 60 to 90 mass%, or may be 75 to 85 mass%. The amount of the acrylic monomer in the total amount of raw material monomers of the vinyl acetate acrylic resin is preferably 5 to 90 mass%, more preferably 10 to 15 mass%, even more preferably 10 to 80 mass%, and still more preferably 10 to 60 mass%, and may be 10 to 40 mass%, or may be 15 to 25 mass%. The total amount of vinyl acetate and acrylic monomers in the total amount of raw material monomers of the vinyl acetate acrylic resin is preferably 80 to 100 mass%, more preferably 90 to 100 mass%, even more preferably 95 to 100 mass%, and may be 100 mass%.

[0028] [Other resins] The acrylic resin may or may not contain an acrylic resin other than the above-mentioned styrene acrylic resin and vinyl acetate acrylic resin, but it is preferable that the acrylic resin does not contain any acrylic resin other than the above-mentioned styrene acrylic resin and vinyl acetate acrylic resin.

[0029] The total amount of the styrene acrylic resin and the vinyl acetate acrylic resin in the acrylic resin is preferably 80 to 100% by mass, more preferably 90 to 100% by mass, and even more preferably 95 to 100% by mass.

[0030] [Method for polymerizing acrylic resin] The acrylic resin can be synthesized by a method such as emulsion polymerization, suspension polymerization, bulk polymerization, solution polymerization, etc. Among these, the acrylic resin is preferably synthesized by emulsion polymerization of a monomer mixture in the presence of a surfactant. The acrylic resin is preferably in the form of particles at the stage of being blended with the coating agent. Therefore, after synthesizing the acrylic resin by solution polymerization, water and, if necessary, a surfactant may be added, and the phase may be inverted into an aqueous system by a known method to form acrylic resin particles.

[0031] When polymerizing the acrylic resin, a polymerization initiator, a buffer, a chain transfer agent, a basic compound, etc. can be used as necessary.

[0032] <PVA resin> The PVA resin is a resin containing a vinyl alcohol group and a vinyl ester group as structural units. The PVA resin may or may not contain other structural units, but it is preferably not contained. The total amount of the vinyl alcohol group and the vinyl ester group in all the structural units of the PVA resin is preferably 80 to 100% by mass, more preferably 90 to 100% by mass, and still more preferably 95 to 100% by mass.

[0033] The saponification degree of the PVA resin is preferably 70 to 95 mol%, more preferably 75 to 90 mol%, still more preferably 80 to 90 mol%, and even more preferably 85 to 90 mol%. Here, the saponification degree refers to the ratio (mol%) of the number of moles of the vinyl alcohol group to the total number of moles of the vinyl alcohol group and the vinyl ester group in the PVA resin. In addition, the saponification degree can be measured in accordance with the method described in JIS K6726 (1994). When the saponification degree in this specification is 70 mol% or less, in the above method, a mixed solution of water:methanol at 1:1 is used as the dissolution solution instead of water for measurement.

[0034] The average degree of polymerization (viscosity average degree of polymerization) of PVA is not particularly limited, but from the viewpoints of viscosity and water solubility, it is preferably 100 to 10,000, more preferably 200 to 5,000, and still more preferably 400 to 4,000. The average degree of polymerization (viscosity average degree of polymerization) can be measured in accordance with the method described in JIS K6726 (1994). The PVA resin can usually be produced by partially saponifying a vinyl ester polymer obtained by polymerizing a vinyl ester compound.

[0035] Examples of the vinyl ester compound include vinyl formate, vinyl acetate, vinyl trifluoroacetate, vinyl propionate, vinyl butyrate, vinyl caprate, vinyl laurate, vinyl versatate, vinyl palmitate, vinyl stearate, pivalic acid, etc., and vinyl acetate is preferably used. These vinyl ester compounds may be used alone or in combination. The PVA resin may be unmodified PVA or modified PVA. The modified PVA resin can be produced by copolymerizing a vinyl ester compound with an unsaturated monomer other than the vinyl ester compound and saponifying the resulting copolymer. The modified PVA resin can also be produced by modifying the hydroxyl group of the vinyl alcohol unit of the unmodified PVA and / or the ester group of the vinyl ester unit with a cationic group, an anionic group, a hydrophobic group, or the like.

[0036] The content of the PVA resin in the coating agent is preferably 0.1 to 5.0 parts by mass, more preferably 0.1 to 3.0 parts by mass, and further preferably 0.1 to 2.0 parts by mass, based on 100 parts by mass of the acrylic resin.

[0037] The total content of the acrylic resin and the polyvinyl alcohol resin in the resin component of the coating agent is preferably 80 to 100 mass%, more preferably 90 to 100 mass%, still more preferably 95 to 100 mass%, and may be 100 mass%. The total content of the acrylic resin and the polyvinyl alcohol resin in the solid content of the coating agent is preferably 80 to 100 mass%, more preferably 85 to 100 mass%, and further preferably 90 to 100 mass%. When the coating agent contains a surfactant, an initiator, a neutralizing agent, a preservative, etc., these are also included in the solid content. The solid content in the coating agent is preferably 0.5 to 55% by mass, more preferably 1.0 to 50% by mass, and further preferably 1.5 to 45% by mass. When the coating agent contains a surfactant, an initiator, a neutralizing agent, a preservative, etc., these are also included in the solid content.

[0038] [Method of manufacturing coating material for open-air deposits] The coating agent for piled up deposits according to the present invention may be produced by adding the PVA-based resin to the acrylic resin. The coating agent for piled up deposits according to the present invention may be produced by polymerizing an acrylic resin from raw material monomers of the acrylic resin and adding the PVA-based resin at least one timing selected from before, during, and after polymerization.

[0039] [Method for preventing dust generation and / or moisture increase in open-air piles] The method for preventing dust generation and / or moisture increase in open-air piles according to the present invention is a method for spraying an O / W type emulsion containing an acrylic resin and a polyvinyl alcohol resin onto open-air piles. The acrylic resin is preferably a styrene acrylic resin and / or a vinyl acetate acrylic resin.

[0040] <Open-air deposits> In the present invention, the open-air piled material to be treated refers to coal, ore, coke, slag, dust, wood chips, paper sludge, etc., piled up in an outdoor storage yard.

[0041] <Spraying method> There are no particular limitations on the method of spraying the coating agent onto open-air piles; it can be sprayed onto the piles from a sprinkler truck or from a top of an open-air stacker, with appropriate pumps and nozzles selected each time.

[0042] The amount of coating to be applied is determined according to the coating agent used and the level of dust or moisture rise prevention required for the piled up material. The diluted coating agent should be applied at a rate of 1 to 3 L / m per surface area of ​​the piled up material.2 It is preferable to scatter the mixture to a certain extent. After the coating agent is sprayed, it is allowed to dry naturally to form a film.

[0043] The coating film formed in this way is thick and strong, so it has a high dust prevention effect. In addition, it is difficult for cracks to form, so moisture does not easily penetrate and it has an excellent effect of preventing moisture from rising. As a result, it is also effective in preventing coal from flowing. EXAMPLES

[0044] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to the following examples.

[0045] [Raw materials] The following raw materials were used: <Styrene-based monomer> ST: Styrene <Vinyl acetate monomer> ·VA: Vinyl acetate <Acrylic monomer> 2EHA: 2-Ethylhexyl acrylate MMA: Methyl methacrylate ·BA: Butyl acrylate AAC: Acrylic acid

[0046] <pva> PVA1 (viscosity average polymerization degree: 2400, saponification degree: 88) PVA2 (viscosity average polymerization degree: 1500, saponification degree: 88) PVA3 (viscosity average polymerization degree: 500, saponification degree: 88) PVA4 (viscosity average polymerization degree: 3300, saponification degree: 88)

[0047] [evaluation] (1) Film strength and thickness The coating agents according to the examples and comparative examples were evaluated as follows. A container measuring 30 cm in length, 15 cm in width, and 10 cm in height was filled with coal with a grain size of 5 mm or less, and the container was allowed to drop naturally 10 times from a height of about 1 cm in this state, adjusting the height of the packed coal layer to 5 cm and making the top surface of the packed layer smooth. A coating agent (o / w type emulsion) was applied to the top surface of the coal layer thus created at a rate of 2 L / m2 relative to the area of ​​the top surface of the coal layer. 2 The coating film was then naturally dried, and the film strength and film thickness of the formed coating film were measured. The film strength was measured using a Yamanaka hardness tester at five points on each sample, and the average value was calculated. The film thickness was measured using a caliper at five points on each sample, and the average value was calculated.

[0048] [Preparation of coating agent: Method 1] A pre-emulsion (solid concentration 60% by mass) containing a styrene monomer or vinyl acetate monomer, an acrylic monomer, PVA, a surfactant (Latemul E-1000A / Kao / 30% by mass product) and an initiator (ammonium persulfate) was added dropwise over 2 hours at a reaction temperature of 85°C under a nitrogen atmosphere, and then aged at 85°C for 3 hours to obtain a reaction liquid. A neutralizing agent was added to the reaction liquid to obtain a coating agent. The mixing ratio of the styrene monomer, vinyl acetate monomer, acrylic monomer, and PVA is as shown in Table 1. The coating material thus obtained was evaluated for film thickness and film strength according to the above-mentioned evaluation methods, and the results are shown in Table 1.

[0049] [Preparation of coating agent: Method 2] A coating agent (O / W type emulsion) was obtained in the same manner as in Method 1, except that PVA was added to the reaction solution together with the neutralizing agent instead of adding PVA to the pre-emulsion. The mixing ratio of the styrene monomer, vinyl acetate monomer, acrylic monomer, and PVA is as shown in Table 1. The coating material thus obtained was evaluated for film thickness and film strength according to the above-mentioned evaluation methods, and the results are shown in Table 1.

[0050] [Preparation of coating agent: Method 3] A coating agent was obtained in the same manner as in Method 1, except that PVA was added to the pre-emulsion and also to the reaction liquid together with the neutralizing agent. The mixing ratios of the styrene monomer, vinyl acetate monomer, acrylic monomer, and PVA are as shown in Table 1. The coating material thus obtained was evaluated for film thickness and film strength according to the above-mentioned evaluation methods, and the results are shown in Table 1.

[0051] [Table 1]

[0052] As shown in Table 1, the coating agent according to the embodiment contains a PVA-based resin, and therefore has a higher film strength than the coating agent according to the comparative example, which does not contain a PVA-based resin.< / pva>

Claims

1. A method for preventing dust generation and / or moisture increase in open-air piles, comprising spraying an O / W type emulsion containing an acrylic resin and a polyvinyl alcohol resin onto the open-air piles, The O / W type emulsion contains 0.1 to 5.0 parts by mass of a polyvinyl alcohol-based resin per 100 parts by mass of an acrylic resin. A method for preventing dust generation and / or moisture increase in open-air deposits.

2. The method for preventing dust generation and / or moisture increase in open-air deposits according to claim 1, wherein the acrylic resin is a styrene acrylic resin and / or a vinyl acetate acrylic resin.