Method for producing cleaning agent

Abstract

To produce a cleaning agent capable of cleaning an object to be cleaned regardless of a surface active agent.SOLUTION: An aqueous solution, which contains sodium carbonate and has an alkaline pH and does not substantially contain a surface active agent, is stored in a storage part 20. A pump 30 is actuated, the aqueous solution of the storage part 20 is supplied into a body 11 of a plasma generator 1 through an inflow part 12 from a solution feeding tank 21, and is circulated into the storage part 20 from an outflow part 13. When a voltage is applied to a pair of electrodes 14 provided in a plasma generation part 10 in an aqueous solution circulation state by a high-frequency pulse power source, a magnetic field is generated between the pair of electrodes 14, and a plasma is generated in the aqueous solution passing through the body 11 by the magnetic field. Thereby, an organic compound capable of dissolving oils and fats such as acetone and ethanol is produced in the aqueous solution, and an aqueous solution which contains the organic compound has a pH maintained to an alkaline region is obtained. The aqueous solution is usable as a cleaning agent.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a method for manufacturing a cleaning agent, and more particularly to a method for manufacturing a surfactant-free cleaning agent.

Background Art

[0002] In the cleaning of metal products, resin products, glass products, ceramics, and fiber products, etc., a cleaning agent containing a surfactant is usually used (for example, Patent Documents 1, 2, and 3). When this cleaning agent is applied to an object to be cleaned, the attached dirt is detached and micellized by the action of the surfactant, so the dirt is removed by rinsing off the cleaning agent with water.

[0003] Although a cleaning agent containing a surfactant has a high cleaning effect, it requires a large amount of water to be rinsed off from the object to be cleaned. Therefore, in the cleaning using it, an increase in the cost for rinsing water is inevitable. In addition, since surfactants are difficult to decompose naturally, they have a high environmental load and there are also concerns about their toxicity to organisms such as fish.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Patent Document 3

Summary of the Invention

Problems to be Solved by the Invention

[0005] The present invention aims to enable the cleaning of an object to be cleaned without relying on a surfactant.

Means for Solving the Problems

[0006] The present invention relates to a method for manufacturing a cleaning agent. This manufacturing method includes a step of preparing an aqueous solution that contains at least one of an alkali metal carbonate and an alkaline earth metal carbonate and has a pH in the alkaline region, and that substantially does not contain a surfactant, and a step of generating plasma in the prepared aqueous solution.

[0007] When plasma is generated in the aqueous solution in this manufacturing method, at least one of the alkali metal carbonate and the alkaline earth metal carbonate or both in the aqueous solution and a part of the water are cleaved to generate carbon monoxide radicals, hydrogen radicals, hydroxyl radicals, etc., and reactions between the generated radicals proceed to generate organic compounds capable of dissolving oils and fats such as carbonyl compounds and alcohols. As a result, an alkaline aqueous solution containing the organic compound is obtained, and this aqueous solution can be used as a cleaning agent.

[0008] The pH of the aqueous solution prepared in this manufacturing method is preferably 9 or higher.

[0009] In one form of this manufacturing method, plasma is generated in the aqueous solution while blowing carbon dioxide or air into the prepared aqueous solution. In this case, it is preferable to control the plasma generation time to 1 minute or more and 5 minutes or less.

[0010] In another form of this manufacturing method, the aqueous solution is prepared, for example, by blowing carbon dioxide or air into an aqueous solution containing at least one of an alkali metal hydroxide and an alkaline earth metal hydroxide.

[0011] The present invention from another aspect relates to a cleaning agent. This cleaning agent contains water, at least one inorganic compound of an alkali metal carbonate and an alkaline earth metal carbonate, and at least one organic compound of a carbonyl compound and alcohols, has a pH in the alkaline region, and substantially does not contain a surfactant. The pH of this cleaning agent is preferably 9 or higher.

Advantages of the Invention

[0012] According to the method for manufacturing a cleaning agent of the present invention, a cleaning agent capable of cleaning an object to be cleaned can be obtained without relying on a surfactant.

[0013] The cleaning agent of the present invention can clean an object to be cleaned without relying on a surfactant.

Brief Description of the Drawings

[0014]

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Mode for Carrying Out the Invention

[0015] In the method for producing a cleaning agent according to the present invention, first, an aqueous carbonate solution, specifically, an aqueous solution containing at least one carbonate selected from alkali metal carbonates and alkaline earth metal carbonates and substantially free of a surfactant is prepared.

[0016] The alkali metal carbonate contained in the aqueous solution is not particularly limited, but usually sodium carbonate or potassium carbonate, which are inexpensive and easily available, are preferable. The alkaline earth metal carbonate is not particularly limited, but usually calcium carbonate, magnesium carbonate or barium carbonate, which are inexpensive and easily available, are preferable. Both the alkali metal carbonate and the alkaline earth metal carbonate may be hydrates, or two or more thereof may be used in combination. In addition, it is preferable to select an alkali metal carbonate in terms of its easy solubility in water.

[0017] An aqueous solution containing a carbonate can usually be prepared by adding an alkali metal carbonate or an alkaline earth metal carbonate or both to water and dissolving them. The amount of carbonate used in the preparation of the carbonate aqueous solution is set such that the aqueous solution adjusted by adding the carbonate is in an alkaline region. Specifically, it is preferable to prepare the target aqueous solution by controlling the addition amount of the carbonate so that the pH is 9 or higher, particularly in an alkaline region where the pH is 11 or higher. Also, the addition amount of the carbonate is preferably controlled so that the aqueous solution remains in an alkaline region with a pH of 7.5 or higher even after the step of generating plasma described later, particularly maintained at a pH of 9 or higher, especially a pH of 11 or higher.

[0018] An aqueous solution containing a carbonate can also be prepared by adding at least one of an alkali metal hydroxide and an alkaline earth metal hydroxide to water to prepare an aqueous solution, and blowing carbon dioxide or air into this aqueous solution. Here, the carbon dioxide wiped into the aqueous solution or the carbon dioxide in the air reacts with the hydroxide in the aqueous solution, and an aqueous solution containing the target carbonate is obtained in the aqueous solution.

[0019] When preparing an aqueous solution containing a carbonate by this method, the amount of hydroxide added to water and the amount of carbon dioxide or air in terms of carbon dioxide blown in are preferably adjusted so that the pH of the aqueous solution becomes the above-mentioned alkaline region due to the generated carbonate.

[0020] The above-mentioned aqueous solution containing a carbonate may contain a bicarbonate or hydroxide of an alkali metal or an alkaline earth metal, and these may be involved in controlling the aqueous solution in an alkaline region. The bicarbonate or hydroxide may be an unreacted substance or a by-product when preparing the target aqueous solution by blowing carbon dioxide or air into an aqueous solution containing a hydroxide.

[0021] When the aqueous solution prepared in this step contains an alkaline earth metal carbonate, since the alkaline earth metal carbonate is hardly soluble in water, a part of it may precipitate. This precipitate is usually preferably separated from the aqueous solution by filtration, centrifugation, or the like before the next step.

[0022] In the method for producing a cleaning agent according to the present invention, next, plasma is generated in the aqueous solution prepared in the previous step. Referring to FIG. 1, an example of a plasma generator that can be used here will be described. In the figure, the plasma generator 1 mainly includes a plasma generation unit 10, a storage unit 20 for the aqueous solution, and a pump 30.

[0023] The plasma generation unit 10 includes a main body 11 formed in a cylindrical shape with a constriction near the center, having an inflow portion 12 for the aqueous solution at one end and an outflow portion 13 for the aqueous solution at the other end, and a pair of electrodes 14 disposed at the constricted portion of the main body 11. The inflow portion 12 is formed in a nozzle shape with a reduced diameter toward the inside of the main body 11, and the aqueous solution can be sprayed into the main body 11 in a mist form. The main body 11 and the inflow portion 12 are usually made of resin such as polytetrafluoroethylene resin or glass.

[0024] The main body 11 is provided with a gas inlet 15 at the end on the side of the inflow portion 12. The gas inlet 15 is for blowing carbon dioxide gas or air into the main body 11 if necessary. The main body 11 is open to the atmosphere so that the internal air pressure and temperature are in equilibrium with the atmospheric pressure and temperature of the installation environment of the plasma generator 1, respectively. The pair of electrodes 14 are formed of, for example, a tungsten-based material and are connected to a high-frequency power source (not shown) for plasma generation. The electrode distance between the pair of electrodes 14 can vary depending on conditions such as the applied voltage and frequency by the high-frequency power source, but is usually 0.5 to 10 mm, preferably 1 to 7 mm, more preferably 2 to 4 mm.

[0025] The storage unit 20 is in communication with the outflow portion 13 of the plasma generation unit 10, and a liquid delivery pipe 21 that communicates with the pump 30 extends, and further includes a cooler 22 for cooling the stored aqueous solution.

[0026] The pump 30 is for sucking the aqueous solution stored in the storage section 20 through the liquid delivery pipe 21 and pumping the sucked aqueous solution into the main body 11 through the inflow section 12 of the plasma generation section 10.

[0027] In this step, the aqueous solution prepared in the previous step is stored in the storage section 20, and the pump 30 is operated. As a result, the aqueous solution is pumped from the storage section 20 to the plasma generation section 10 through the liquid delivery pipe 21 and sprayed into the main body 11 from the inflow section 12 as indicated by the arrow in the figure. The aqueous solution sprayed into the main body 11 passes between the pair of electrodes 14 as indicated by the arrow in the figure and moves toward the outflow section 13, and returns from the outflow section 13 to the storage section 20. Therefore, during the operation of the pump 30, the aqueous solution in the storage section 20 continues to circulate through the liquid delivery pipe 21, the pump 30, and the plasma generation section 10.

[0028] During the circulation of the aqueous solution, in the plasma generation section 10, the high-frequency power supply is operated and a high-frequency voltage is applied to the pair of electrodes 14. As a result, a magnetic field is generated between the pair of electrodes 14, and plasma is generated in the aqueous solution passing through the magnetic field. The plasma generated in the aqueous solution cleaves a part of the molecules of carbonate and water to generate carbon monoxide radicals, hydrogen radicals, hydroxyl radicals, etc., and at the same time, the reaction between the radicals generated in parallel with this proceeds to generate organic compounds such as carbonyl compounds such as acetone and diacetone alcohol, and alcohols such as ethanol and isopropanol.

[0029] In the plasma generation unit 10, as the plasma treatment time of the aqueous solution becomes longer, there is a possibility that organic compounds with a large number of carbon atoms, which have a large environmental impact, are generated, or the generated organic compounds may cleave and decompose. Also, decomposition may be superior to the generation of organic compounds, and the pH of the aqueous solution after plasma treatment may decrease and reach or approach the neutral range. Therefore, the plasma treatment time of the aqueous solution, that is, the circulation time of the aqueous solution by the pump 30, is preferably limited to such an extent that organic compounds with a relatively small environmental impact, for example, low molecular weight organic compounds such as acetone and ethanol having 6 or less carbon atoms, are generated. Specifically, although it varies depending on the plasma generation conditions, usually at least 1 minute (that is, 1 minute or more) is ensured, while the upper limit of the treatment time is preferably controlled to 60 minutes or less, more preferably 10 minutes or less, and particularly preferably 5 minutes or less.

[0030] Note that the aqueous solution in the storage unit 20 is preferably cooled by the cooler 22 in order to suppress the loss due to the volatilization of the low molecular weight organic compounds generated by plasma treatment, and is usually preferably maintained at 22°C or lower.

[0031] The aqueous solution that has been plasma-treated during circulation contains at least one organic compound among carbonyl compounds and alcohols in addition to at least one inorganic compound among the alkali metal carbonate and alkaline earth metal carbonate that were initially contained. And since the carbonic acid derived from the carbonate is consumed by the plasma treatment, the pH of this aqueous solution is maintained in the alkaline range of 7.5 or more.

[0032] The generation of organic compounds by plasma treatment is liable to be affected by the installation environmental temperature of the plasma generator 1. For example, when the installation environmental temperature is generally 22°C or lower, both carbonyl compounds and alcohols are liable to be generated in the aqueous solution by plasma treatment. In particular, when the installation environmental temperature is 15°C or lower, the generation of alcohols tends to become remarkable.

[0033] Although the plasma-treated aqueous solution is substantially free of surfactants, it basically contains the above-mentioned inorganic compounds and exhibits good detergency because its pH is in the alkaline range, preferably pH 9 or higher. However, since it further contains the above-mentioned organic compounds, the removability of oils and fats is enhanced. Therefore, this aqueous solution is effective as a cleaning agent for products made of various materials such as metal products, resin products, glass products, ceramics, and fiber products.

[0034] The cleaning method using this cleaning agent is not particularly limited. Usually, after immersing the object to be cleaned in the cleaning agent, the cleaning agent adhering to the object to be cleaned is rinsed off with running water. During the immersion, in order to enhance the cleaning effect, the dirt adhering to the surface of the object to be cleaned may be wiped off using a brush or the like.

[0035] In this embodiment, in order to enrich the carbon source and oxygen source that contribute to the generation of the organic compound, carbon dioxide or air can also be blown from the gas inlet 15 into the aqueous solution sprayed from the inflow part 12 of the plasma generation part 10 into the main body 11.

[0036] Also, in the above-described embodiment, an aqueous solution containing the required carbonate is stored in the storage part 20 and plasma-treated while circulating this aqueous solution. However, in the manufacturing method of the present invention, the above-described aqueous solution containing hydroxide is stored in the storage part 20 and circulated, and carbon dioxide or air is blown from the gas inlet 15 of the plasma generation part 10 to prepare an aqueous solution containing the required carbonate in the main body 11, and this aqueous solution can also be changed to be plasma-treated by the magnetic field formed in the main body 11.

[0037] [Experimental Example] In the following experimental examples, the plasma generator 1 described in the above embodiment was used. The specific specifications of the plasma generator 1 used here are as follows. ◎ Plasma generation part 10 · Main body 11 Made of polytetrafluoroethylene resin · Inflow part 12 Made of polytetrafluoroethylene resin, inlet diameter: R3 / 4 (20A) · Gas inlet 15 Diameter: 1 mm · Electrode 14 Made of tungsten, electrode distance: 3 mm · High-frequency power supply: High-frequency pulse power supply (model number "MPP04 - A4 - 200 - A" manufactured by Kurita Manufacturing Co., Ltd.), AC pulse: ±4 kV, duty ratio: 10% (0.5 μs), frequency: 200 kHz, power consumption: 1,000 W ◎ Reservoir 20 · Cooler 22 Immersion-type cooler (model number "200TN" manufactured by Inai Seiei-do Co., Ltd.) · Liquid delivery pipe 21 Blade hose made of polyvinyl chloride resin (inner diameter 19 mm, outer diameter 26 mm) ◎ Pump 30 Model number "NF3 - 250S" manufactured by Kawamoto Manufacturing Co., Ltd., flow rate: 28 L / min

[0038] <Experimental Examples 1 - 12> 1.5 g of sodium carbonate (reagent grade 99.8% of Fuji Film Wako Pure Chemical Industries, Ltd.) was dissolved in 4 L of pure water to prepare an aqueous sodium carbonate solution with a pH of 10.9, and this aqueous sodium carbonate solution was stored in the reservoir 20. Also, the main body 11 of the plasma generation unit 10 was set so that the internal temperature and pressure were in equilibrium with the temperature and atmospheric pressure of the installation environment of the plasma generator 1.

[0039] After cooling the aqueous sodium carbonate solution in the reservoir 20 to 10°C with the cooler 22, the pump 30 was operated, and the cooled aqueous sodium carbonate solution was continuously pumped from the reservoir 20 through the liquid delivery pipe 21 and sucked into the inflow section 12 of the plasma generation unit 10.

[0040] In addition, carbon dioxide or air was supplied to the aqueous sodium carbonate solution supplied from the inflow portion 12 into the main body 11 at a rate of 80 mL / min from the gas inlet 15, and at the same time, the high-frequency power supply was operated to apply a high-frequency pulse voltage to the electrode 14, thereby generating plasma in the aqueous sodium carbonate solution passing through the main body 11. Then, the aqueous sodium carbonate solution plasma-treated in the main body 11 was returned to the storage portion 20 through the outflow portion 13, thereby circulating the aqueous sodium carbonate solution.

[0041] The circulation of the aqueous sodium carbonate solution was continued so that the plasma treatment time of the aqueous sodium carbonate solution in the main body 11 was as shown in Table 1, thereby converting the aqueous sodium carbonate solution in the storage portion 20 into the target cleaning agent. The cleaning agent thus produced was collected from the storage portion 20 and analyzed by a gas chromatography-mass spectrometer (model number "GC-MS-QP2010Ultra" manufactured by Shimadzu Corporation). The analysis conditions are as follows.

[0042] ·Column used: DB-FFAP (polar column) ·Analysis amount (aqueous solution amount): 1 μL ·Split ratio: 1:10 ·Number of cleaning times: 1 time before and after measurement ·Number of co-washing times: 2 times

[0043] Table 1 shows the analysis results of the cleaning agents manufactured by carrying out the above-described steps on days when the air temperature at the installation location of the plasma generator 1 was different.

[0044] <Experimental Examples 13 and 14> A cleaning agent was manufactured by operating in the same manner as in Experimental Examples 1 to 12, except that the aqueous sodium carbonate solution in the storage portion 20 was not cooled and air was introduced from the gas inlet 15 instead of carbon dioxide, and the cleaning agent was analyzed in the same manner as in the same experimental example. The results are shown in Table 1.

[0045] <Experimental Examples 15 and 16> A cleaning agent was produced by operating in the same manner as in Experimental Examples 1 to 12, except that the aqueous sodium carbonate solution in the storage section 20 was not cooled, and the cleaning agent was analyzed in the same manner as in the same experimental examples. The results are shown in Table 1.

[0046] <Experimental Examples 17 - 19> A cleaning agent was produced by operating in the same manner as in Experimental Examples 1 to 12, except that plasma was not generated in the aqueous sodium carbonate solution passing through the main body 11 by not operating the high - frequency power supply, and the cleaning agent was analyzed in the same manner as in the same experimental examples. The results are shown in Table 1.

[0047] <Experimental Examples 20 - 23> A cleaning agent was produced by operating in the same manner as in Experimental Examples 1 to 12, except that the aqueous sodium carbonate solution in the storage section 20 was not cooled and plasma was not generated in the aqueous sodium carbonate solution passing through the main body 11 by not operating the high - frequency power supply, and the cleaning agent was analyzed in the same manner as in the same experimental examples. The results are shown in Table 1.

[0048]

Table 1

[0049] [Evaluation] According to Experimental Examples 1 to 23, acetone is generated while the pH of the plasma - treated aqueous sodium carbonate solution is maintained in the alkaline region. In particular, when the installation environment temperature of the plasma generator 1 is 22°C or lower, ethanol also tends to be generated together with acetone, and when the installation environment temperature is 15°C or lower, the generation of ethanol becomes significant. Also, according to Experimental Examples 8 to 12, acetone generation can be observed even with a short plasma treatment time (circulation time), and there is a possibility that the amount of acetone generated may decrease when the plasma treatment time (circulation time) becomes longer.

Explanation of Signs

[0050] 1 Plasma generator 10 Plasma generation section 11 Main body 12 Inflow section 13 Outlet section 14 Electrode 20 Storage section

Claims

1. A step of preparing an aqueous solution that contains at least one of an alkali metal carbonate and an alkaline earth metal carbonate and has a pH in the alkaline region and substantially does not contain a surfactant; A step of generating plasma in the aqueous solution; A method for manufacturing a cleaning agent comprising the above.

2. The method for manufacturing a cleaning agent according to Claim 1, wherein the pH of the aqueous solution is 9 or higher.

3. The method for manufacturing a cleaning agent according to Claim 1 or 2, wherein plasma is generated in the aqueous solution while blowing carbon dioxide or air into the aqueous solution.

4. The method for manufacturing a cleaning agent according to Claim 3, wherein the plasma generation time is controlled to be 1 minute or more and 5 minutes or less.

5. The method for manufacturing a cleaning agent according to Claim 1 or 2, wherein the aqueous solution is prepared by blowing carbon dioxide or air into an aqueous solution containing at least one of an alkali metal hydroxide and an alkaline earth metal hydroxide.

6. Water, At least one inorganic compound of an alkali metal carbonate and an alkaline earth metal carbonate, At least one organic compound of a carbonyl compound and alcohols, Containing, Having a pH in the alkaline region and substantially not containing a surfactant, A cleaning agent.

7. The cleaning agent according to Claim 6, wherein the pH is 9 or higher.

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