JPH07109368A - Coating material - Google Patents

Abstract

PURPOSE: To provide a covering material as a substitute covering material of covering soil for a refuse reclaim site and the like comprising a formalin- based resin precondensate modified with a specific hydrophilic compound, which material inhibits incrustation or deposition on the inwall of piping of an spreading apparatus thereby simplifying or dispensing with maintenance of the piping of the spreading apparatus.

CONSTITUTION: There is provided the aimed covering material comprising (A) a foaming agent, (B) an acid catalyst and (C) a formalin-based resin precondensate, the component C being modified with (D) a hydrophilic compound having at least two hydroxyl groups in the molecule. Preferably, as the component C is employed a urea resin and as the component D, a polyvinyl alcohol, a polyethylene glycol, a polypropylene glycol or glycerol, and 0.1-30 pts.wt. out of 100 pts.wt. of the component C are modified with the component D.

COPYRIGHT: (C)1995,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a covering material, and more specifically to a covering material as a substitute for covering soil at a landfill disposal site.

[0002]

2. Description of the Related Art In recent years, the shortage of landfill sites has become a serious problem. As a countermeasure, it may be possible to construct a new landfill site, but there are many difficult aspects such as securing land, cost, and understanding of local residents. Therefore, how to effectively use the existing landfill disposal site and make it last longer is an effective measure that can be considered at present. At the landfill site, soil is covered on the waste to protect the surrounding environment, but this results in the limited landfill volume being consumed.

Japanese Unexamined Patent Publication (Kokai) No. 59-161507 discloses a method in which waste is dumped at a landfill site and then covered with an impermeable sheet such as polyvinyl chloride, polyethylene or polyester. In most of the actual landfill disposal sites, the next landfill is carried out every day or every few days on top of the landfill site on the previous day (previous day), and when it is covered with impermeable sheets. Must remove the sheet each time before landfill work. In addition, when covering and removing the sheet, the worker has to move directly on the dust surface, which is not preferable in terms of hygiene. Furthermore,
Since such a sheet blocks the contact between the waste and the soil and the air outside, the landfill waste is not decomposed, and the land required for the use of the land is significantly delayed in stabilization.

Japanese Unexamined Patent Publication (Kokai) No. 4-131171 discloses a method of coating waste with a disintegrating polymer after dumping the waste at a landfill site. This sheet will undergo natural decomposition and will eventually collapse, so there is no problem with respect to the stabilizing effect of the land, but it takes several months to collapse, so landfill work every day or every few days. In the actual landfill disposal site where the above-mentioned operation is performed, there are the same problems as in JP-A-59-161507 with respect to covering and removing sheets.

Japanese Patent Laid-Open No. 55-35913 discloses a method in which a water-soluble synthetic resin is injected by a high-pressure pump, then mixed with a curing agent in an ejector, and then the surface of dust is coated with a foamy substance mixed with air. There is. With this method, it is not possible to obtain a sufficient expansion ratio for the drug weight,
The amount of drug used per unit area increases, which is not preferable in terms of cost. Further, since the foaming ratio is low, the foamy substance becomes dense, and therefore, when dust or the like is further buried in the upper surface by stacking the foamy substance, compression / collapse of the foamy substance cannot be expected so much.

US Pat. No. 4,421,788 and US Pat. No. 4,519,338 show a method of coating a refuse surface with a foam formed by mixing and curing a urea resin precondensate with a foam consisting of an acid catalyst and a surfactant. Has been done. The foam used in this method covers the surface without disappearing for a long period of time, and since it has a high expansion ratio, it is compressed and disintegrated due to dust etc. buried in the upper surface after drying, and its volume is almost Since it becomes negligible, it leads to extension of the life of the disposal site. However, since this foam has a very high curing rate, the cured foam is apt to adhere to and deposit on the inner wall of the pipe of the spraying device, and this tendency is particularly remarkable at low temperatures. Further, since the attached deposits are insoluble in water and cannot be removed sufficiently by flushing cleaning, it is necessary to manually clean the inside of the pipes with a brush or the like, resulting in a decrease in work efficiency.

[0007]

SUMMARY OF THE INVENTION It is an object of the present invention to suppress the deposits deposited on the inner wall of the spraying device piping and to simplify or omit the maintenance of the spraying device piping.
An object is to provide an improved curable formalin-based resin foam coating material.

[0008]

The present invention provides a coating material comprising a foaming agent, an acid catalyst and a formalin-based resin precondensate, the formalin-based resin precondensate having at least two hydroxy groups in the molecule. The gist is a coating material modified with a hydrophilic compound.

The foaming agent is preferably a combination of a foaming surfactant and water.

As the foaming surfactant, a hydrophilic compound having sufficient foaming power and foam stability even in an acidic aqueous solution of pH 5 or less and modified with a hydrophilic compound having at least two hydroxy groups in the molecule is modified. The modified formalin-based resin initial condensate must be capable of being uniformly dispersed in the foam immediately after mixing with the modified formalin-based resin initial condensate until the curing is almost completed. The surfactant to be used here may be any of anionic surfactant, cationic surfactant, nonionic surfactant and amphoteric surfactant, and one kind may be used, or plural kinds may be used in combination. May be. Examples of those surfactants include alkyl sulfuric acid and salts thereof, alkyl sulfonic acid and salts thereof, alkylbenzene sulfonic acid and salts thereof, alkylnaphthalene sulfonic acid and salts thereof, alkyl fatty acids and salts thereof, alkyl diphenyl ether sulfonic acid and salts thereof. Salt, alkyl ether fatty acid and its salt, α-olefin sulfonic acid and its salt, dialkyl sulfosuccinic acid and its salt, N-acyl sulfonate, alkyl ether sulfuric acid and its salt, polyoxyethylene alkylphenyl ether sulfuric acid and its salt, Alkylamido sulfuric acid and salts thereof, alkyl ether phosphoric acid and salts thereof, alkyl allyl ether phosphoric acid and salts thereof,
There are tertiary and quaternary ammonium salts, carboxybetaine, sulfobetaine, and those in which a hydrogen atom in the alkyl group of the above-mentioned surfactant is partially or wholly replaced with a fluorine atom to form a fluorinated alkyl group.

The formalin-based resin initial condensate is generally at least one kind of formalin-based resin such as low-molecular weight urea resin, melamine resin, phenol resin, urea melamine resin, urea phenol resin (hereinafter referred to as "low-molecular-weight urea resin, etc."). ") And formalin. Of these, the urea resin initial condensate is preferable because it is excellent in biodegradability when it becomes a urea resin cured product later, the cost is low, and the curing degree is relatively easy to control.

Conditions for the modified formalin-based resin initial condensate used in the present invention are as follows. First, a low molecular weight urea resin or the like is reacted with formaldehyde to produce a formalin-based resin initial condensate. A hydrophilic compound having at least two hydroxy groups (hereinafter referred to as a “hydroxy group-containing compound”) must be added to form a hydroxy group-containing compound-modified formalin-based resin initial condensate, which is a low molecular weight urea resin or the like. If the hydroxy group-containing compound is added after the reaction of formaldehyde to simply form a mixed solution of the formalin resin initial condensate and the hydroxy group-containing compound, the effect of suppressing foam deposits in the spraying device piping cannot be obtained. The following conditions basically start the curing immediately after mixing with the foam formed from the surfactant solution containing the acid catalyst at the general ambient temperature or at the same time as the foam is formed to maintain the volume of the formed foam. That is, the curing is to proceed and be completed rapidly. If the curing speed is slow, bubbles may disappear before curing,
The hydroxy group-containing compound-modified formalin resin initial condensate dispersed in the foam may flow out, and as a result, a cured foam may not be obtained, or a very weak foam may be formed. . This phenomenon becomes very remarkable when the rate of modification of the hydroxy group-containing compound in the formalin-based resin initial condensate is extremely high, and sufficient performance as a coating material cannot be satisfied.

On the other hand, the effect of suppressing foam deposits in the spraying apparatus piping, which should be exhibited in the present invention, is realized by forming a foam using a formalin-based resin initial condensate modified with a certain amount or more of a hydroxy group-containing compound. To be done. At this time, if the modification ratio of the hydroxyl group-containing compound of the formalin-based resin initial condensate is too low, the effect of suppressing foam deposits in the spray device piping cannot be obtained, so periodic cleaning maintenance of the piping is required, and especially Daily cleaning is required at low temperatures where deposits are high. Therefore, in order to form a foam having a sufficient volume and strength as a coating material and a property to be compressed and disintegrated after drying, and to obtain the effect of suppressing foam deposits in the spraying equipment piping, the formalin-based material used in the present invention is used. The modification rate of the hydroxyl group-containing compound of the resin initial condensate is 0.1% by weight or more and 30% by weight or less, preferably 0.5% by weight or less, with respect to the solid content of the formalin-based resin initial condensation product. Above 2
It is preferably 0% by weight or less.

Examples of the hydroxy group-containing compound include polyvinyl alcohol (hereinafter sometimes abbreviated as "PVA"), water-soluble polymer compounds such as polyvinyl formal and polyvinyl butyral, polyethylene glycol, polypropylene glycol, glycerin, ethylene glycol, Examples thereof include polyhydric alcohols such as propylene glycol, and monosaccharides or polysaccharides such as glucose and fructose. Of these, PVA, polyethylene glycol or glycerin is particularly suitable for the present invention. P
VA can easily control the amount of reactive, that is, unreacted hydroxy groups, and can provide a material having a high water affinity. Glycerin is suitable because it has a large amount of hydroxy groups per unit weight and is highly reactive. Furthermore, polyethylene glycol and polypropylene glycol have an ether bond in the molecule and have a high water affinity.

The acid catalyst used in the present invention may be an organic acid / inorganic acid or a monobasic acid / polybasic acid, but it has a solubility in water of 0.1% by weight or more and is modified with a hydroxy group-containing compound. A foaming agent that rapidly starts to cure immediately after mixing with the formalin-based resin initial condensate and gives a pH of 5 or less, which is an acidic region sufficient to complete the curing in a short time, and coexists with a surfactant. It must be one that does not impair the foaming power of the surfactant by causing a chemical reaction or a decomposition reaction over time. The acid catalyst to be used here may be used alone or as a mixture of plural kinds. Examples of the acid catalysts include hydrochloric acid, sulfuric acid, nitric acid, phosphoric acid, phosphoric acid primary Sodium hydrogen, acetic acid, citric acid,
Examples include tartaric acid and oxalic acid.

Examples of the method for forming the bubbles include a method in which a compressed gas such as air is used in a surfactant solution to cause foaming in a foaming device, a method in which a mixer is used for stirring, and the like.

The foaming and curing reaction may be carried out simultaneously by mixing the foam-forming component and the reactive component at the same time, but the foam is sufficiently formed and the cured resin is formed along the film of the foam. Is good. A preferred method of carrying out the latter method is to foam a surfactant solution containing an acid catalyst in a foaming machine using a compressed gas, send the foam through a pipe toward a spraying part, and in the middle of this pipe. This is to combine with a formalin-based resin initial condensate modified with a hydroxy group-containing compound, mix, react, and discharge and spray from a pipe outlet to a dust surface or the like.

Immediately after both the acid and the hydroxy group-containing compound-modified formalin-based resin initial condensate are mixed with each other, the foam rapidly hardens, and the foam released / sprayed does not disappear. It can maintain and cover the garbage surface for a long time. Further, by using the hydroxy group-containing compound modified formalin-based resin initial condensate, the foam which is rapidly curing immediately after mixing of both drugs can be attached and deposited on the inner wall of the pipe. Therefore, it is possible to suppress the clogging of the pipe of the spraying device, and it is possible to simplify or omit maintenance such as cleaning.

0.1 to 10 parts by weight of a dye or pigment of a color other than white is mixed with the foaming or reaction raw material per 100 parts by weight of the solid content of the coating material, or mixed in the foaming or reaction raw material. It may be mixed, or mixed with the mixture during foaming, mixing or reaction, or with the product of foaming, mixing and reaction. As a result, it is possible to add a concealing effect that prevents birds and small animals from approaching, and a harmony effect that makes the color tone suitable for the environment (green, brown, or gray).

The colors other than white include not only chromatic colors but also achromatic colors, and the brightness is preferably 8 or less, more preferably 6 or less.
The following is good.

The present invention is not limited to a covering material for a landfill disposal site, and it can be used for deodorizing purposes such as at a sludge accumulating site for producing a bad odor, and for preventing incineration ash scattering of waste. .

[0022]

EFFECTS OF THE INVENTION By using the coating material according to the present invention for protecting the surrounding environment and prolonging the life of the landfill in a landfill disposal site, etc., it has sufficient strength as a coating material and stability over time, and after drying. It is formed from a surfactant solution containing an acid catalyst in the spray device piping without impairing the function of forming a foam that has the property of being compressed and pulverized by artificial external pressure to make its volume almost negligible. It is possible to suppress the foam that adheres to and accumulates on the inner wall of the pipe between the point where the foam and the hydroxy group-containing compound-modified formalin resin initial condensate are mixed until it is discharged to the outside. In many cases, even if there is temporary adhesion / accumulation, it can be washed extremely easily with water, and maintenance such as cleaning the piping part regularly with a brush etc. is remarkable. It is possible to Ryakuka or omitted, it is possible to realize the opening of the improvement and hassle of pipe care work efficiency.

[0023]

EXAMPLES The present invention will be described in more detail with reference to examples below, but the present invention is not limited thereto.

(Examples 1 to 5) At a landfill site for refuse, it has sufficient strength as a covering material as an alternative material for covering soil and stability over time, and it is compressed and crushed by artificial external pressure after drying, and its volume is almost ignored. The following experiment was conducted to determine whether to form a foam having the properties that make it possible. At room temperature, 10 ml of an aqueous solution containing 0.7 wt% of phosphoric acid and 1.3 wt% of anionic surfactant (sodium dodecyl sulfate based on reagent) was placed in a 200 ml cup and the volume of the foam was reduced to about 200 ml using a stirrer. Foamed. Next, polyvinyl alcohol-modified urea resin initial condensates having various modification ratios (wt%) shown in Table 1 (reagent-based urea and formaldehyde were mixed at a molar ratio of 1: 1.5, and polyvinyl alcohol was used as Kuraray Poval ( Trademark) PVA-10
5 (manufactured by Kuraray Co., Ltd.) was added and 10 ml of an aqueous solution containing 35 to 40 wt% of 40% was prepared and stirred for 20 seconds. After the cured foam was left at room temperature for 6 days, the state of the foam (volume change (shrinkage) and compression / grindability) was observed. The results are shown in Table 1.

Next, the following experiment was conducted in order to investigate the effect of suppressing the adhered and deposited foam on the inner wall of the pipe of the spraying device. In the open air, an aqueous solution (I) containing 0.7 wt% of phosphoric acid and 1.3 wt% of an anionic surfactant (reagent-based sodium dodecyl sulfate) was placed in a tank 1 shown in FIG. Polyvinyl alcohol-modified urea resin initial condensate (reagent-based urea and formaldehyde in a molar ratio of 1:
1.5 and mixed with polyvinyl alcohol as Kuraray Poval (trademark) PVA-105 (manufactured by Kuraray Co., Ltd.)
Was added and the mixture was prepared by stirring at 40 ° C. for 24 hours), and an aqueous solution (II) containing 35 to 40 wt% thereof was filled in each tank 2. Kuraray Poval P manufactured by Kuraray Co., Ltd. used here
VA-105 (trademark) has a polymerization degree of 500 and a saponification degree of 98.
Was 99 mol%. Solution I sucked from tank 1 by pump 5 is passed through pipes 3 and 8 to foamer 11
Sent to. At the same time, the compressor or compression cylinder 6
More air is sent to the foaming device 11 through the pipe 9, and the solution I
And mixed to form a foam. On the other hand, the solution II sucked out of the tank 2 by the pump 7 is mixed with the foam composed of the solution I and air at a position after the foaming device 11 through the pipes 4 and 10, and the hardening of the foam starts at this moment. A foam is formed. The cured foam is discharged to the outside through the pipe 12 and the transparent tube 13. Solutions I and II
Was discharged at a flow rate of 1000 ml / min for a total of 2000 ml / min and foam was discharged for 3 minutes. Then, the pump 7 was stopped to stop the supply of the solution II and only the solution I was allowed to flow for 1 minute.
Next, the pump 5 is stopped to stop the supply of the solution I, the end of the pipe 4 is changed from the tank 2 to the water tank 14, and then the pump 7 is started to start the pipe 4, the pump 7, and the pipe 1.
0, the pipe 12 and the transparent tube 13 were washed with water for 1 minute. After stopping the pump 7 to stop the supply of water, the state of the cured product of foam attached to the inner wall of the transparent tube 13 was observed. The results are shown in Table 1.

(Examples 6 and 7) Instead of the urea resin initial condensate, a phenol resin initial condensate Shaunol BRL was used.
The same experiment as in Example 1 was performed except that -113, BRL-2683 (both manufactured by Showa High Polymer Co., Ltd.) and different amounts of modifying polyvinyl alcohol were used. The results are shown in Table 1.

Comparative Example 1 0.7 wt% phosphoric acid and anionic surfactant (reagent-based sodium dodecyl sulfate)
Aqueous solution (I) containing 1.3 wt% and unmodified urea resin precondensate (prepared by mixing reagent-based urea and formaldehyde at a molar ratio of 1: 1.5 and stirring at 40 ° C. for 24 hours) Example 1 in an aqueous solution (II) containing 35 wt% of
In the same manner as above, observation of foam and observation experiment of adhered and deposited foam were conducted. The results are shown in Table 1.

Comparative Example 2 0.7 wt% phosphoric acid and anionic surfactant (reagent-based sodium dodecyl sulfate)
Aqueous solution (I) containing 1.3 wt% and the same urea resin initial condensate as used in Comparative Example 1, which was not modified during production, was added with polyvinyl alcohol later to form a mixed solution. With respect to (II), the foam observation and the adhesion and deposition foam observation experiment were performed in the same manner as in Example 1. As the solution II in this case, a solid content of the amino resin (urea-formaldehyde) initial condensate is 23 wt% by appropriately adding 10 wt% aqueous polyvinyl alcohol solution and water to an aqueous solution containing 35 wt% of the urea resin precondensate. The one prepared as described above was used. The results are shown in Table 1.

[0029]

[Table 1]

(Examples 8 to 11) Instead of PVA, polyethylene glycol manufactured by Sanyo Kasei Co., Ltd., PEG400 (trademark) (molecular weight 400) and PEG200 (trademark) (molecular weight 200) and manufactured by Wako Pure Chemical Industries, Ltd. Foam observation and adhesion-deposited foam observation experiment were performed in the same manner as in Example 1 using the ones modified with the reagent glycerin and ethylene glycol at the modification ratio (wt%) based on the solid content of the urea resin initial condensate shown in Table 2. Was done. The results are shown in Table 2.
Shown in.

[0031]

[Table 2]

Example 12 Using a large-sized apparatus having the same type as the apparatus shown in FIG. 1, 0.7 wt% of phosphoric acid and an anionic surfactant (reagent-based sodium dodecyl sulfate) were used.
Aqueous solution (I) containing 1.3 wt% was added to tank 1 and the result of Example 1
The aqueous solution (II) containing 35 wt% of the urea resin initial condensate modified with polyvinyl alcohol (Kuraray Co., Ltd. Kuraray Poval PVA-105 (trademark)) prepared in the same manner as used in Example 1 was filled in each tank 2. did. If necessary, add brown to the aqueous solution (II) (red 2 16 wt%, red 102 1
7 wt%, yellow No. 4 50 wt% and blue No. 2 17 wt%) or green (yellow No. 4 60 wt% and blue No. 1 40 wt%) were dissolved. A cured foam was formed in the same manner as in Example 1, and white, brown, and green soil substituting covering materials were applied to each of about 50 m ² of landfill disposal sites to a thickness of about 70 mm and about 1 by the method of the present invention.
Coated to 00 mm. After covering in the evening and observing the next morning,
Only when it was coated with a white 70 mm thick soil-covering alternative coating material, dust was extracted by the crows at 3 to 4 places.

[Brief description of drawings]

FIG. 1 is a schematic view of an example of an apparatus for carrying out the method of the present invention.

[Explanation of symbols]

1 ... Tank of aqueous solution containing phosphoric acid and anionic surfactant 2 ... Tank of aqueous solution containing polyvinyl alcohol-modified urea and resin initial condensation product 3, 4, 8, 9, 10, 12 ... Piping 5, 7 ... Pump 6 ... Compressor or compression cylinder 11 ... Foamer 13 ... Transparent tube 14 ... Water tank

Claims (6)

[Claims] 1. A coating material comprising a foaming agent, an acid catalyst and a formalin-based resin initial condensate, wherein the formalin-based resin initial condensate is modified with a hydrophilic compound having at least two hydroxy groups in the molecule. Covering material. 2. The coating material according to claim 1, wherein the formalin-based resin initial condensate is a urea resin. 3. The hydrophilic compound having at least two hydroxy groups in the molecule is polyvinyl alcohol,
The coating material according to claim 1, which is polyethylene glycol, polypropylene glycol, or glycerin. 4. The formalin-based resin initial condensate in a proportion of 0.1 to 30 parts by weight relative to 100 parts by weight thereof,
4. A compound modified with a hydrophilic compound having at least two hydroxy groups in the molecule.
The coating material according to. 5. The coating material according to claim 1, wherein the formalin-based resin initial condensate is 500 to 45000 parts by weight with respect to 100 parts by weight of a foaming agent. 6. The coating material according to claim 1, further comprising 0.1 to 10 parts by weight of a dye or pigment other than white based on 100 parts by weight of the solid content of the coating material. Coating material.