JPH09279372A - Cleaning method and rust preventive - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain such a cleaning method that org. matter such as contaminants and the active component of a cleaning liquid in the waste water of a cleaning liquid or in the waste water of a rinsing liquid can be easily removed in a short time, that the inorg. water-soluble rust preventing component can be maintained in the water phase, that the treated water phase can be reused and thereby, the amt. of water can be largely decreased, and further, that the amt. of the rust preventive used and the cost for the processing of waste water can be decreased, and that the method is economically excellent. SOLUTION: In this cleaning method, a metal surface is cleaned with a cleaning liquid containing a water content and then rinsed with a rinsing liquid. The cleaning and rinsing processes are carried out by using (1) a cleaning liquid and a rinsing liquid containing a water-soluble inorg. rust preventive which is not adsorbed by activated carbon, or (2) a cleaning liquid and a rinsing liquid both containing a water-soluble inorg. rust preventive which is not adsorbed by activated carbon. The waste water of the rinsing liquid after rinsing is treated with activated carbon to adsorb the org. matter in the waste liquid. The obtd. soln. after the treatment is reused as a rinsing liquid containing the water-soluble inorg. rust preventive.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention mainly relates to an aqueous cleaning method for surfaces of metals such as iron, aluminum and copper. More particularly, it relates to a cleaning method that enables efficient reuse of the rust preventive agent and water used in the cleaning and rinsing steps.

[0002]

2. Description of the Related Art Conventionally, oils and fats, machine oils, and cuttings existing on the metal surface of electronic parts, precision parts, or jigs and tools used for assembling and processing them (hereinafter referred to as electronic parts or precision parts) Various methods such as solvent cleaning and water-based cleaning are used to remove dirt mainly composed of organic substances such as oil, grease, wax, liquid crystal, and flux. More specifically, hydrocarbon solvent cleaning with kerosene, benzene, xylene, etc .; chlorine solvent cleaning with trichlorethylene, tetrachloroethylene, etc .; fluorocarbon solvent cleaning with trichlorotrifluoroethane, etc .; water cleaning with surfactants, builders, etc. Has been done. Especially electronic, electrical,
Freon-based solvent cleaning or chlorine-based solvent cleaning has been mainly used for parts such as machines. The reason is a)
In addition to being highly washable / flame-retardant, b) easy to dry, c) there is no risk of rusting because it does not come into contact with water, d) no wastewater treatment facility is required, etc. The advantages of can be mentioned.

However, the cleaning method using a chlorofluorocarbon-based solvent and a chlorine-based solvent has serious problems in safety, toxicity and environmental pollution. In addition, hydrocarbon solvents, especially benzene, xylene, etc., are highly toxic compounds that are designated as hazardous substances under the Industrial Safety and Health Act, and are flammable. It is necessary to secure enough from the aspect of management and management. Therefore, under the present circumstances, the demand for water-based cleaning that does not use these solvents is rapidly increasing.

Generally, in the water-based cleaning method, it is possible to provide a safe and excellent cleaning power by properly selecting the cleaning agent constituents such as a surfactant and a builder, and further, it is possible to provide a water-soluble rust preventive agent. The inclusion of the agent can prevent the generation of rust.

[0005]

However, the conventional rust-prevention method for water-based cleaning still has a problem with regard to wastewater treatment and is not sufficiently satisfactory. In other words, in the recycling / reuse treatment of the cleaning wastewater and rinse wastewater containing the water-soluble rust preventive agent, the dirt component and the cleaning agent residue are removed, and at the same time the water-soluble rust preventive agent component is also removed. There is a drawback that it is necessary to add an anticorrosive agent. Therefore, in particular, in the rinsing step, in order to maintain the rinsing property, the rinsing liquid is treated while being intermittently or continuously discarded, and the wastewater is separately installed and treated to replenish the rinsing liquid. A method of adding a water-soluble rust preventive agent to water is adopted, which increases the amount of water-soluble rust preventive agent used and the wastewater treatment load.
As a result, there is a drawback that the wastewater treatment facility becomes large.

Therefore, in the water-based cleaning, the dirt component and the cleaning agent residue in the cleaning wastewater and the rinse wastewater after cleaning are efficiently removed, and the water-soluble rust preventive agent component is efficiently left in the water after the treatment. By circulating and reusing as a rinse solution, a cleaning method that can maintain both the rust prevention function of the cleaning solution and the rinse solution and the wastewater treatment without the large processing cost and equipment required in the conventional method is desired. It is rare.

In order to meet such demands, for example, in Japanese Patent Laid-Open No. 7-292487, a water-soluble rust preventive agent that passes through an ultrafiltration membrane is used, and a cleaning solution and a rinse solution containing the water-soluble rust preventive agent are used. Is treated with an ultrafiltration membrane and the filtrate is reused as a rinsing solution to satisfy the above requirements. However, in the above-mentioned conventional technique, most of organic substances such as a soil component or a surfactant in a cleaning agent residue are low-molecular substances having a molecular weight of several hundred to 2,000, and therefore, they should be effectively removed by an ultrafiltration membrane. Is difficult (alternative metal cleaning technology, Mamiya, p. 209, 1
993, General Technology Center). Therefore, the low-molecular contaminants that pass through these ultrafiltration membranes gradually accumulate in the rinsing liquid, reducing the rinsability, and, as with the conventional wastewater treatment method, the low-molecular organic contaminants in the rinsing liquid are removed. In order to remove it, it is necessary to remove even the water-soluble rust inhibitor component and add a new water-soluble rust inhibitor to the treated water. Further, in terms of clogging of the membrane, chemical resistance of the membrane, etc., the applicable stains and cleaning agents are limited, and they are not yet satisfactory, and the development of a cleaning method that satisfies the above requirements has been awaited.

[0008]

Under such circumstances, the inventors of the present invention have conducted extensive studies and as a result, as a result of containing a water-soluble inorganic rust preventive which is not adsorbed on activated carbon in a cleaning solution and a rinsing solution, and rinsing the solution after rinsing. When rinsing wastewater is treated with activated carbon, only organic substances consisting of dirt components and cleaning agent residue in the rinsing wastewater are adsorbed on the activated carbon, water-soluble rust inhibitor components pass without being adsorbed, and the liquid after treatment is rinsed. Also, it can be reused as a rinse liquid that also has sufficient rust resistance, and by using a specific water-diluting solution of a cleaning agent and a specific water-soluble inorganic rust preventive agent, the water-solubility in the cleaning waste water after cleaning can be improved. An inorganic rust preventive agent can be left, and organic substances consisting of dirt components and cleaning agent residue can be easily separated and removed, and the separated water phase can be reused as a solution having a rust preventive function for cleaning agent dilution. Rinse By providing a rough rinsing step between the two and performing the same treatment, the activated carbon treatment load in the rinsing step can be reduced, and the treated liquid can be reused as a rough rinsing liquid having a rust preventive function. Etc. The present invention has been completed based on such facts by further research.

That is, the gist of the present invention is (1) in a method of washing a metal surface with a washing liquid containing water and then rinsing with a rinse liquid, (1) a water-soluble inorganic rust preventive that is not adsorbed by the washing liquid and activated carbon. After cleaning and rinsing with a rinsing solution containing a cleaning agent or (2) a cleaning solution and a rinsing solution containing a water-soluble inorganic rust preventive that is not adsorbed on activated carbon in any of the cleaning solution and rinsing solution, (2) A cleaning method characterized in that the rinsing wastewater is treated with activated carbon to adsorb and remove organic matter in the rinsing wastewater, and the resulting aqueous solution is reused as a rinsing solution containing a water-soluble inorganic rust preventive agent. The cleaning liquid is a nonionic surfactant alone, or a linear or branched saturated or unsaturated hydrocarbon compound having 6 to 30 carbon atoms, and an alkyl ester having 6 to 40 carbon atoms. And the cleaning method according to the above (1), which comprises one or more selected from the group consisting of alkyl ethers having 6 to 40 carbon atoms and a nonionic surfactant as active ingredients, and (3) the cleaning liquid is water. Dilute or evaporate water to give a content of active ingredient of 10% by weight
The washing method according to the above (2), wherein 30% by weight or more of the active ingredient contained in the aqueous solution is separated from the aqueous phase when the aqueous solution is allowed to stand at a temperature of 20 to 100 ° C. for 30 minutes. A water-soluble inorganic rust preventive obtained by providing an apparatus for removing organic matters in the washing wastewater while keeping the washing wastewater obtained after washing at 20 ° C to 100 ° C in the washing step and removing the organic matters from the washing wastewater by the apparatus. The cleaning method according to any one of (1) to (3) above, wherein the aqueous solution containing the agent is reused for dilution of the cleaning agent.
A rough rinsing step is provided between the cleaning step and the rinsing step, and the rough rinsing wastewater obtained after the rough rinsing is added at 20 ° C to 100 ° C.
A device for removing organic matter in the rough rinsing wastewater is provided while keeping the temperature at 0 ° C, and an aqueous solution containing a water-soluble inorganic rust preventive obtained by removing the organic matter from the rough rinsing wastewater is reused as a rough rinsing solution. (1)-
(4) The cleaning method according to any one of (6), wherein the water-soluble inorganic rust preventive that is not adsorbed on activated carbon is a silicate, a borate, a phosphate, a nitrite, a molybdate, a tungstate, or an alkali metal. (1) which is one or more selected from the group consisting of hydroxide, carbonate and hydrogen carbonate.
(5) The cleaning method according to any one of (7), wherein the silicate is
General formula xM ₂ O · ySiO ₂ (In the formula, M represents Na and / or K, and y / x = 0.5.
４4.0. ) The crystalline silicate and / or hydrate thereof represented by the above (6), the cleaning method according to the above (6),
Silicates, borates, phosphates, nitrites, molybdates, tungstates, and alkali metal hydroxides,
The rust preventive agent used in the cleaning method according to any one of (1) to (5) above, which is selected from the group consisting of carbonates or hydrogen carbonates, and (9) silicate is represented by the general formula xM ₂ O.ySiO ₂ (formula In the above, M represents Na and / or K, and y / x = 0.5.
４4.0. ) The rust preventive agent according to (8) above, which is a crystalline silicate and / or a hydrate thereof.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION In the cleaning method of the present invention, a metal surface is cleaned with a cleaning solution containing water and then rinsed with a rinse solution. After cleaning and rinsing with a rinsing solution containing a cleaning agent or (2) a cleaning solution and a rinsing solution containing a water-soluble inorganic rust preventive that is not adsorbed on activated carbon in any of the cleaning solution and rinsing solution, The rinsing wastewater is treated with activated carbon to adsorb and remove organic matters in the rinsing wastewater, and the aqueous solution obtained by this is reused as a rinsing solution containing a water-soluble inorganic rust preventive agent. Further, each step of the cleaning method may include only a cleaning step and a rinsing step, or a rough rinsing step may be provided between the cleaning step and the rinsing step.

The water-soluble inorganic rust preventive which is not adsorbed on the activated carbon used in the present invention is not particularly limited, and examples thereof include silicates, borates, phosphates, nitrites, molybdates and tungstates. Alkali metal hydroxides, carbonates, hydrogen carbonates and the like are preferable, and these are used alone or in combination of two or more kinds. Among these, those that do not adversely affect the oil-water separation ability are particularly preferable,
Those that do not interfere with the removal of organics from the wash and rough rinse wastewaters are preferred. That is, the water-soluble inorganic rust preventive agent of the present invention is preferably used for an oil / water separation step.

Specific examples of the silicate include ortho, meta, and silicates such as No. 1 to No. 4 sodium silicate or potassium silicate, and No. 3 sodium silicate and No. 4 sodium silicate are particularly preferable. As a general formula of the anhydride, xM ₂ O · ySiO ₂ (In the formula, M represents Na and / or K, and y / x = 0.5.
４4.0. Particularly preferred is a crystalline silicate represented by) and / or a hydrate thereof. Here, M represents Na and / or K, y / x = 0.5 to 4.0, and 2.0 to
4.0 is more preferable. This crystalline silicate is Fe, C
It has a rust preventive effect in common with typical three metals of u and Al. If y / x exceeds 4.0, it is difficult to handle due to high viscosity.
If it is less than 0.5, the solubility in water is lowered and crystals may be precipitated, which is not suitable for use as a water-soluble rust preventive agent. The crystalline silicate may be a hydrate, and in this case, the molar ratio of H ₂ O to the crystalline silicate of the hydrate is usually 0 to 20.

Further, other water-soluble inorganic rust preventives of the present invention further include boric acid salts such as tetraboric acid, perboric acid, sodium metaborate, ammonium borate and ammonium pentaborate, and phosphate salts such as trisodium phosphate. Nitrite such as sodium nitrite, molybdate such as sodium molybdate, tungstate such as sodium tungstate, alkali metal hydroxide such as lithium hydroxide and potassium hydroxide, alkali such as sodium carbonate and potassium carbonate Examples thereof include hydrogencarbonates of alkali metals such as metal carbonates, sodium bicarbonate and potassium bicarbonate.

The organic substance adsorption / removal device used in the rinsing step of the present invention is a device for adsorbing and treating the organic component consisting of the dirt component and the cleaning agent residue in the rinsing wastewater with activated carbon. The type of activated carbon used here is not particularly limited. That is, for example, sawdust, charcoal, coconut shells, peat, lime, powdered activated carbon or the like activated pulp waste liquid and the like, and steam and regenerated by heating with combustion gas, hydrochloric acid, sulfuric acid, caustic soda, organic solvent, etc. Activated carbon that has been regenerated by regenerating chemicals can also be used. In particular, coconut shell granular activated carbon is easy to handle,
It is preferable that it is well separated from water, has a small installation area, is easy to automate and regenerate, and is further preferably acid-alkali treated in advance to reduce impurities such as ash remaining in a trace amount in the activated carbon.

The method for treating the rinse wastewater with activated carbon is not particularly limited, but specifically, the rinse wastewater discharged in the rinse step is pumped at a temperature of 20 to 100 ° C., preferably 20 to 70 ° C. , It is sent to a commercially available small cartridge tank filled with activated carbon or a metal vessel type filter to continuously adsorb and remove organic substances, and the treatment liquid containing a water-soluble inorganic anticorrosive agent is circulated and reused as a rinse liquid. do it. The cleanliness after the rinsing wastewater is regenerated in this way is preferably about 1 to 1000 ppm in COD. By the rinsing process of the present invention as described above, the rinsing process can be closed and can be circulated and reused substantially without drainage.

The water-soluble inorganic rust preventive which is not adsorbed on the activated carbon in the present invention is used by being contained in the rinse solution in an amount of 0.001 to 1.0% by weight, preferably 0.002 to 0.5% by weight. The water-soluble inorganic rust preventive agent of the present invention may be contained not only in the rinse liquid but also in the cleaning liquid or the rough rinse liquid.
When the water-soluble inorganic rust preventive agent is contained in the cleaning liquid or the rough rinsing liquid, its content is 0.001 to 1.0% by weight, preferably 0.002 to 0.5% by weight. As the rinse liquid and the rough rinse liquid used in the present invention, tap water,
Industrial water, ion-exchanged water, reclaimed water from wastewater, or the like is used.

The washing liquid used in the washing step of the present invention is not particularly limited, but a washing liquid having the following active ingredients and properties is preferable. (1) Active ingredient: a nonionic surfactant alone or a straight or branched chain saturated or unsaturated hydrocarbon compound having 6 to 30 carbon atoms, an alkyl ester having 6 to 40 carbon atoms, and carbon A combination of one or more compounds selected from the group consisting of alkyl ethers of the number 6 to 40 with a nonionic surfactant. (2) Properties: The washing solution is diluted with water or water is evaporated,
20% aqueous solution containing 10% by weight of the active ingredient.
When allowed to stand at a temperature of 100 ° C. for 30 minutes, 30% by weight or more, preferably 50% by weight or more of the active ingredient contained,
More preferably, 70% by weight or more is separated from the aqueous phase.

The cleaning liquid used here is not particularly limited as long as it has the above-mentioned active ingredients and properties. That is, a nonionic surfactant is essential as an active ingredient, and a nonionic surfactant may be used alone, or a straight chain or branched chain having 6 to 30 carbon atoms may be added to the nonionic surfactant. It may be used in combination with one or more compounds selected from the group consisting of saturated or unsaturated hydrocarbon compounds of 6), alkyl esters having 6 to 40 carbon atoms, and alkyl ethers having 6 to 40 carbon atoms.

For example, a nonionic surfactant having a cloud point of 100 ° C. or lower, and a hydrocarbon compound used for improving detergency against oily stains, sparingly water-soluble alkyl esters and alkyl ethers. A cleaning liquid in which the above compounds account for 50% by weight or more of the organic components in the active components of the cleaning liquid is mentioned. Of these, in order to improve the cleaning property, these components are contained in 70% of the cleaning liquid active ingredient.
It is more preferable that it accounts for at least wt%. Here, the cloud point means that when 10 to 30 mL of the cleaning liquid active ingredient diluted 20 times with ion-exchanged water is put into a test tube and the temperature is raised at a temperature rising rate of 1 ° C./minute, the liquid becomes cloudy. When the temperature exceeds this temperature, the nonionic surfactant in the aqueous solution is gradually separated from the aqueous phase.

Examples of the nonionic surfactants include ether types such as alkyl ether type, alkyl allyl ether type and alkyl thioether type; ester type such as alkyl ester type and sorbitan alkyl ester type; polyoxyalkylene alkyl amines and the like. Condensation type with amine; Condensation type with amide such as polyoxyalkylene alkyl amide; Pluronic or Tetronic type obtained by random or block condensation of polyoxyethylene and polyoxypropylene; Surfactant such as polyethyleneimine type . Among these, those having a hydrocarbon group having 4 to 22 carbon atoms are particularly preferable, and a detergent composition containing one or more such nonionic surfactants is
The affinity for oily soil is increased and the cleaning property is improved, and the cleaning wastewater after cleaning and the rough rinsing wastewater mixed with the soil easily show a clear cloud point, and the separability of organic substances is particularly good. Such a nonionic surfactant is contained in the cleaning liquid active ingredient in an amount of 3 to 100% by weight, preferably 10 to 10% by weight.
It is suitable to contain 0% by weight, particularly preferably 20 to 100% by weight.

As the hydrocarbon compound, for example, paraffins and olefins having a linear or branched saturated or unsaturated bond having 6 to 30 carbon atoms, preferably 10 to 18 carbon atoms, which are liquid at the temperature of the washing step. , Or aromatic,
Examples include hydrocarbon compounds containing an alicyclic group. Further, examples of the alkyl esters include monoesters, diesters and triesters having 6 to 40 carbon atoms, preferably 8 to 36 carbon atoms, which are liquid at the temperature of the washing step, and particularly higher fatty acids having 6 to 18 carbon atoms. Ester of higher alcohol having 1 to 18 carbon atoms; ester of higher fatty acid having 6 to 18 carbon atoms and diol or triol having 2 to 8 carbon atoms; higher alcohol having 1 to 18 carbon atoms and dicarboxylic acid having 2 to 8 carbon atoms Alternatively, esters with tricarboxylic acids are preferred. As the alkyl ethers, dialkyl ethers having 6 to 40 carbon atoms, preferably 10 to 20 carbon atoms are preferable.

In the property described in the above (2) of the cleaning liquid in the present invention, if the active ingredient separated from the aqueous phase is less than 30% by weight, the separation of the active ingredient from the wash wastewater and the rough rinse wastewater is not sufficient, As a result, organic stain components such as oil stains are easily dissolved, emulsified and dispersed in the aqueous phase, and the separability of organic substances is not sufficiently improved. Further, even if the aqueous solution after the separation treatment is reused for diluting the cleaning liquid and as a rough rinsing liquid, the content of organic substances such as oil stains is large, causing recontamination of the cleaning liquid and the rough rinsing liquid, and Maintenance is significantly reduced. From the above, in order to maintain the cleaning performance of the cleaning liquid, the rinsing property of the rough rinsing liquid, and enable the reuse of the cleaning wastewater and the rough rinsing wastewater, as described above in (2)
It is preferable to use a cleaning liquid active ingredient in which 50% by weight or more, and more preferably 70% by weight or more of the active ingredient contained under the condition of (1) is separated. Here, the amount of the active ingredient separated from the aqueous phase is measured by COD or TOC (total organic carbon). This TOC value is basically measured by the combustion-infrared analysis method described in "Organic carbon (TOC)" in JIS-K0102 "Factory wastewater test method", for example, manufactured by Shimadzu Corporation, TOC-
500.

The mechanical force applied in the washing step, rough rinsing step and rinsing step in the present invention is not particularly limited, but a temperature of 20 to 100 ° C., preferably 20 to 100 ° C.
In the temperature range of 70 ° C., the dipping method, the ultrasonic cleaning method, the rocking method, the spray method, etc., which are circulated and agitated by applying a gas such as a stirring blade, a pump, and air, can be performed alone or in combination. .

Generally, the rough rinsing step works so as not to bring the high-concentration active ingredient and dirt component adhering to the object to be washed in the washing step directly to the rinsing step, but if the washing is continuously carried out, the rough rinsing step is performed. Since the concentration of the liquid gradually approaches the concentration of the cleaning liquid, it is necessary to renew the rough rinse liquid for a certain period. However, in the rough rinsing step in the present invention, even if continuous washing is continued, by constantly circulating the activated carbon treatment device for removing the organic matter, the organic matter concentration can be maintained low and constant without updating the rough rinsing solution, Moreover, the rust prevention function can be maintained. In particular, it becomes more effective when the concentration of the active ingredient in the cleaning liquid is high.

The apparatus for removing organic matter from the cleaning wastewater used in the cleaning step of the present invention and the apparatus for removing organic matter from the rough rinsing wastewater used in the rough rinsing step should be a method capable of efficiently performing oil-water separation. However, it is not particularly limited. For example, the washing wastewater after washing and the rough rinsing wastewater after rough rinsing are 20 ° C. or higher, preferably 20 to 7
While being kept at 0 ° C., a static separation method, a skimming method, a method using a separation membrane, a centrifugal separation method, an electric separation method, etc. may be used alone or in combination of two or more. Such organic matter may be removed by providing respective receiving tanks for the cleaning wastewater after cleaning, the rough rinsing wastewater after rough rinsing, or a dedicated tank for separation, and directly to the cleaning tank and the rough rinsing tank. These removing devices may be connected to carry out the circulating treatment continuously or intermittently. The cleanliness after the cleaning wastewater and the rough rinsing wastewater are regenerated by using these devices, the COD is 500 to
It is preferably 50,000 ppm.

Also in the rinsing step of the present invention, in addition to the treatment of the rinsing waste water with activated carbon, the same device as that used in the above-mentioned washing step or rough rinsing step is used as a device for removing the organic substances in the rinsing waste water. It may be provided. That is, the rinsing wastewater after the rinsing step is kept at 20 ° C. or higher, preferably 20 ° C. or higher.
While maintaining at 70 ° C., a stationary separation method, a skimming method, a method using a separation membrane, a centrifugal separation method, an electrical separation method, etc. may be used alone or in combination of two or more. Such organic matter may be removed by providing each receiving tank for the rinsing wastewater after the rinsing step or a dedicated tank for separation, and directly or intermittently connecting these removing devices to the rinsing tank. Circulation processing may be performed. Further, these devices may be provided either before or after the treatment with activated carbon.

In particular, when separating the oil / water from each other, it is preferable to heat the washing wastewater, the rough rinsing wastewater, or the rinsing wastewater to a temperature not lower than the cloud point of the nonionic surfactant to be used, because the separation is performed more effectively. That is, at temperatures above the cloud point, the nonionic surfactant loses water solubility,
As a result, the oily soil that has been solubilized or emulsified in the waste water cannot be retained in the water, and the oily soil is separated by floating or sinking in the water depending on its specific gravity. The nonionic surfactant itself loses water solubility and is separated from water.

The cleaning method of the present invention has a particularly excellent effect when cleaning electronic parts, precision parts and jigs and tools used in the assembling process thereof. Here, the electronic part means, for example, a computer. And its peripherals, home appliances, office automation equipment,
Hoop materials used for contact members such as IC lead frames, resistors, capacitors and relays used in other electronic application equipment; gears, cam shafts, springs used in office automation equipment, watches, computer equipment, toys, home appliances, etc. , Metal parts such as shafts, bearings and outer cases; magnetic recording parts used for video / audio recording / reproducing parts and related parts; photoelectric conversion parts used for CDs, PDs, copying machines, optical recording machines, etc. Say. Precision parts refer to, for example, electrical parts, precision machine parts, optical parts and the like. The electrical parts include, for example, electric parts such as brushes, rotors, stators, housings, etc .; ticket issuing parts used in vending machines and various devices; currency inspection parts used in vending machines, cash dispensers, etc. Precision machine parts refer to, for example, precision drive equipment, bearings used in video recorders, powder metallurgy parts, and processed parts such as cemented carbide chips. Other components include, for example, eyeglass frames, watch cases, watch belts, and the like. Further, the jigs and tools used in the assembly processing step include jigs and tools handled in various steps such as manufacturing, molding, processing, assembling, and finishing of precision parts such as those shown in the above-mentioned examples of parts, It refers to various equipment that handles these precision parts, parts thereof, and the like.

Among the above, the cleaning method of the present invention is particularly suitable for cleaning electronic parts or precision parts having a metal surface mainly having organic contaminants such as oil, machine oil, cutting oil, grease, liquid crystal and flux. Although the features are demonstrated,
It is not limited to these examples.

[0030]

The present invention will be described in more detail with reference to the following Examples and Comparative Examples, but the present invention is not limited to these Examples and the like.

<Test Material> 2 g / m ² of press oil (manufactured by Nippon Oil Co., Ltd., Unipres PA-5) was applied to the following steel test piece (manufactured by Taikyu Equipment Co., Ltd., 10 cm × 15 cm). Test material 1: Cold rolled steel plate / SPCC-B Test material 2: Aluminum plate / A5052P Test material 3: Tough pitch copper plate

<Method for treating activated carbon of rinsing wastewater> While maintaining 1 liter of rinsing wastewater containing dirt, cleaning liquid active ingredient and water-soluble inorganic rust preventive agent at 25 ° C, activated carbon (made by Kuraray Chemical Co., Ltd.) , Kuraray Coal GC) 1
It is sent to a glass container (lower inlet, upper outlet, diameter 10 cm) filled with liter (about 500 g) and the flow rate is 0.1 L /
It was circulated for 30 minutes for adsorption treatment.

<Method for separating organic matter from washing wastewater or rough rinsing wastewater> Washing wastewater or rough rinsing wastewater containing dirt, an active ingredient of the washing liquid and a water-soluble inorganic rust preventive is kept at 60 ° C. for 5 minutes and then stirred. Was stopped, placed in a separating funnel, allowed to stand for 30 minutes while maintaining at 60 ° C., and the lower layer solution after separation was reused.

<Active ingredient of cleaning liquid> The cleaning liquid 1 is (PO
E) ₁₃ lauryl ether (cloud point 92 ° C.): 10%, (P
OE) ₂ hexyl ether (cloud point 16 ° C.): 40%,
(POE) ₂ butyl ether (cloud point above 100 ° C): 3
0%, water: 20%, cleaning liquid 2 is (POE) ₁₃ lauryl ether (cloud point 92 ° C.): 10%, (POE) ₂ hexyl ether (cloud point 16 ° C.): 20%, (POE) ₂ butyl ether ( Cloud point 100 ° C or higher): 10%, olefin (average carbon number 14): 50%, water: 10%, cleaning liquid 3
Is (POE) ₁₃ lauryl ether (cloud point 92 ° C.): 1
5%, (POE) ₂ hexyl ether (cloud point 16 ° C.):
A detergent having a composition of 20%, dibutyl adipate: 30%, dioctyl ether: 25%, water: 10% was used. (POE) _n : indicates polyoxyethylene, and n indicates the average number of added moles.

<Evaluation Method> (1) Evaluation of Recycling / Reusability of Washing, Rinse Rinse, and Rinse Wastewater (a) Method A, (b) Method B, (c) Method C, and (d) In the washing order of the construction method D, the washing wastewater, the rough rinsing wastewater, and the rinsing wastewater are in an initial state in which there is no accumulation of dirt and cleaning liquid active ingredients, and in a state where the liquid after washing, rough rinsing, and rinsing is regenerated and reused. The recycling / reusability of the cleaning wastewater was evaluated by evaluating the rust prevention property and the cleaning property.

(A) Construction method A The water-soluble rust preventives shown in Tables 1 to 3 were added to 1 liter of a cleaning liquid prepared by diluting the active ingredient of the cleaning liquid 2 with ion-exchanged water 10 times by weight and cleaning at 60 ° C. Step, with 1 liter of ion-exchanged water containing the water-soluble rust preventive agent shown in Tables 1 to 3,
In the washing consisting of a rinsing step at 25 ° C., a hot air drying step at 120 ° C. for 10 minutes, evaluations were carried out in the initial washing and the regenerant washing. However, the addition amount of the water-soluble rust preventive agent in Tables 1 to 3 indicates the addition amount of each of the cleaning liquid and the rinsing liquid. The initial cleaning means a cleaning using a newly prepared cleaning liquid, that is, an initial cleaning liquid, and then a rinsing cleaning with a newly prepared rinse liquid, that is, an initial rinse liquid. The regenerating liquid washing is performed by adding 5% by weight of Unipres PA-5 to the initial washing liquid, and again adding 10% by weight of the active ingredient of the washing liquid to the lower layer liquid treated by the organic substance separation method of the washing liquid. Next, 0.2% by weight of a cleaning agent and 0.1% by weight of Unipres PA-5 were added to the initial rinsing liquid, and the rinsing liquid was treated by the activated carbon treatment method to rinse.

(B) Method B Water-soluble rust preventives shown in Tables 1 to 3 are added to 1 liter of a cleaning liquid prepared by diluting the active ingredient of the cleaning liquid 2 with ion-exchanged water 10 times by weight, and cleaning is carried out at 60 ° C. Step, 60 with 1 liter of ion-exchanged water containing the water-soluble rust preventive agent shown in Tables 1 to 3
Initial washing and regenerated liquid washing in the washing consisting of a step of rough rinsing at ℃, a step of adding the water-soluble rust preventives shown in Tables 1 to 3 at 25 ° C, a hot air drying step of 120 ° C for 10 minutes. Was evaluated. However, the addition amount of the water-soluble rust preventive agent in Tables 1 to 3 shows the addition amount of each of the cleaning liquid, the rough rinsing liquid, and the rinsing liquid. The initial cleaning is cleaning in which cleaning with an initial cleaning liquid, rough rinsing with an initial rough rinsing liquid, and rinsing with an initial rinsing liquid are performed. The regenerating liquid washing is performed by adding 5% by weight of Unipres PA-5 to the initial washing liquid, and again adding 10% by weight of the active ingredient of the washing liquid to the lower layer liquid treated by the organic substance separation method of the washing liquid. Then 2% by weight of the initial rough rinse with detergent.
5% by weight of Unipres PA-5 was added, and rough rinsing was performed with the lower layer liquid treated by the organic substance separation method of the washing liquid. Next, 0.2% by weight of the cleaning liquid active ingredient and 0.1% by weight of Unipres PA-5 were added to the initial rinse liquid,
Rinsing and washing are performed with the liquid treated by the activated carbon treatment method of the rinse liquid.

(C) Method C 1 liter of the active ingredient of the cleaning liquid 1 was used as a cleaning liquid.
Initially, in a washing step at 0 ° C., a rinsing step at 25 ° C. with 1 liter of ion-exchanged water to which the water-soluble rust preventive agent shown in Tables 1 to 3 is added, and a hot air drying step at 120 ° C. for 10 minutes. The evaluation was performed by washing and washing with the regenerant. However, the addition amount of the water-soluble rust preventive agent in Tables 1 to 3 shows the addition amount in the rinse solution. The initial cleaning means a cleaning using a newly prepared cleaning liquid, that is, an initial cleaning liquid, and then a rinsing cleaning with a newly prepared rinse liquid, that is, an initial rinse liquid. The washing with the regenerating liquid is performed by adding 5% by weight of Unipres PA-5 to the initial cleaning liquid. Next, 0.2% by weight of a cleaning agent and 0.01% by weight of Unipres PA-5 were added to the initial rinsing liquid, and the rinsing liquid was rinsed with the liquid treated by the activated carbon treatment method.

(D) Method D 1 liter of the active ingredient of the cleaning liquid 3 was used as the cleaning liquid.
25 ° C. washing step, step of rough rinsing at 60 ° C. with 1 liter of ion-exchanged water to which the water-soluble rust preventive agent shown in Tables 1 to 3 is added, water-soluble rust preventive agent shown in Tables 1 to 25 In the cleaning including the rinsing step at 120 ° C., the hot air drying step at 120 ° C. for 10 minutes, the initial cleaning and the regenerant cleaning were evaluated. However, the addition amount of the water-soluble rust preventive agent in Tables 1 to 3 shows the addition amount of each of the rough rinsing liquid and the rinsing liquid.
The initial cleaning is cleaning in which cleaning with an initial cleaning liquid, rough rinsing with an initial rough rinsing liquid, and rinsing with an initial rinsing liquid are performed. Regeneration liquid cleaning is Unipres P as the initial cleaning liquid.
Add 5% by weight of A-5 and wash. Then, 10% by weight of a cleaning agent and 0.5% by weight of Unipres PA-5 are added to the initial rough rinsing liquid, and rough rinsing is performed with the lower layer liquid treated by the organic substance separation method of the cleaning liquid. Next, 0.2% by weight of the active ingredient of the washing solution and 0.01% by weight of Unipres PA-5 were added to the initial rinsing solution, and the rinsing solution was rinsed with the solution treated by the activated carbon treatment method.
In each step of washing, rough rinsing, and rinsing used in each construction method, stirrer stirring and compressed air at 1 L / min.
At the same time, agitation by blowing into the liquid was also used, and immersion cleaning was performed with a tact for 3 minutes in each step.

(2) Rust-preventing property The rust generation state and the presence or absence of discoloration of the test plate after drying were visually observed and evaluated based on the following criteria. ◯: No rust or discoloration occurred on the surface or the end surface. X: Rust and discoloration can be confirmed.

(3) Detergency The amount of stains remaining on the surface of the test plate after drying was visually evaluated based on the following criteria. ◯: Very good with no residual dirt (press oil). Δ: Slightly bad, with a few residual dirt substances.

(4) Evaluation of reduction of activated carbon load in the rinsing process accompanying removal of organic substances from the rinsing wastewater Since the amount of the rough rinsing wastewater adhering to the test plate and brought into the rinsing process is always almost constant, the rinsing is performed. The activated carbon treatment load in the process depends on the organic matter concentration in the rough rinsing wastewater. Therefore, if the organic matter separation rate before and after the organic matter removal treatment of the rough rinsing wastewater is obtained, the reduction rate of the activated carbon treatment load in the rinsing step can be obtained. In the method for removing organic matter from the rough rinsing wastewater, the pretreatment liquid after stirring and the lower layer liquid after separation are sampled and the TOC (total organic carbon amount) is measured to obtain the A value and the B value to reduce the load of activated carbon treatment. The reduction rate of the activated carbon treatment load was calculated as follows: rate = separation rate of organic matter = (100 × (A−B) ÷ A). The measuring device is Shimadzu
A TOC-500 type measuring instrument was used.

(5) Evaluation of Separation Rate The cleaning liquids 1 to 3 were diluted with ion-exchanged water to prepare 60 liters of an aqueous solution containing 10% by weight of the active ingredient.
Stir for 5 minutes while maintaining the temperature at ℃, then stop stirring,
Put it in a separating funnel and keep it at 60 ℃ for 30 minutes,
Sampling the pretreatment liquid after stirring and the lower layer liquid after separation,
Each TOC (total organic carbon content) was measured and the A value,
Separation rate of organic matter = separation rate of active ingredient = 100 x
(A−B) ÷ A was calculated. The results are shown in Table 4,
It was confirmed that all of the cleaning liquids 1 to 3 have the property that 70% by weight or more of the active ingredient is separated and removed.

Examples 1 to 19 As is clear from the results shown in Tables 1 and 2, all Examples 1 to 19 were good in cleaning property, rust preventive property, and reproducibility / reusability of cleaning liquid and rinsing liquid. In addition, Examples 4, 7, 1
It was also found that Nos. 1, 13, 17, 18, and 19 were excellent in the ability to remove organic substances from the rough rinsing wastewater, and the activated carbon treatment load in the rinsing step could be reduced by 85% or more.

Comparative Examples 1 to 8 As shown in Table 3, rust occurred in Comparative Examples 1 to 3 in which no rust preventive agent was added. On the other hand, in Comparative Examples 4 and 5 in which the water-soluble organic rust preventive adsorbed by activated carbon was used, the rust preventive was adsorbed and removed by activated carbon, and the solution after treatment had no rust preventive function and rust occurred. . Furthermore, in Comparative Examples 4 and 5, the ability to remove organic substances in the cleaning wastewater and the rough rinsing wastewater decreases, so in Comparative Example 4, even if the liquid after the cleaning wastewater treatment is reused, the cleaning property decreases, In 5, the organic matter concentration in the rough rinsing liquid also increased,
It was found that the cleanability was reduced. In addition, Comparative Examples 6 to 8
Caused rust due to the adsorption and removal of the rust preventive agent on the activated carbon.

[0046]

[Table 1]

[0047]

[Table 2]

[0048]

[Table 3]

[0049]

[Table 4]

[0050]

EFFECTS OF THE INVENTION According to the present invention, it is possible to easily remove stains and organic substances such as active ingredients of cleaning liquid in cleaning wastewater, rough rinsing wastewater and rinsing wastewater in a short time, and at the same time, to prepare a water-soluble inorganic rust preventive component. Can be maintained in the aqueous phase. Furthermore, since the treated aqueous phase can be reused as a cleaning liquid diluting liquid having a rust preventive function, a rough rinsing liquid or a rinsing liquid, the amount of water used during the cleaning process can be significantly reduced, The amount of agent used and wastewater treatment costs can be reduced, and it is economically superior.

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Claims (9)

[Claims] 1. A method of cleaning a metal surface with a cleaning solution containing water and then rinsing with a rinse solution,
(1) A rinsing liquid containing a cleaning liquid and a water-soluble inorganic rust preventive that is not adsorbed on activated carbon, or (2) A cleaning liquid containing a water-soluble inorganic rust preventive that is not adsorbed on activated carbon in both the cleaning liquid and the rinsing liquid, Along with washing and rinsing with a rinse solution, the rinse wastewater after rinse is treated with activated carbon to remove organic substances in the rinse wastewater by adsorption, and the resulting aqueous solution is used as a rinse solution containing a water-soluble inorganic rust inhibitor. A cleaning method characterized by reuse. 2. The cleaning liquid contains a nonionic surfactant alone, or a linear or branched saturated or unsaturated hydrocarbon compound having 6 to 30 carbon atoms, an alkyl ester having 6 to 40 carbon atoms, The cleaning method according to claim 1, which comprises, as active ingredients, one or more kinds selected from the group consisting of alkyl ethers having 6 to 40 carbon atoms and a nonionic surfactant. 3. A cleaning solution, which is diluted with water or evaporated to form an aqueous solution containing 10% by weight of the active ingredient, is prepared.
The washing method according to claim 2, wherein 30% by weight or more of the active ingredient contained has the property of separating from the aqueous phase when left standing for 30 minutes at a temperature of 0 to 100 ° C. 4. The washing step is provided with a device for removing organic substances in the washing wastewater while keeping the washing wastewater obtained after washing at 20 ° C. to 100 ° C., and removing the organic substances from the washing wastewater by the device. The cleaning method according to any one of claims 1 to 3, wherein an aqueous solution containing a water-soluble inorganic rust preventive agent is reused for diluting the cleaning agent. 5. A rough rinsing step is provided between the cleaning step and the rinsing step, and a device for removing organic substances in the rough rinsing waste water is provided while keeping the rough rinsing waste water obtained after the rough rinsing at 20 ° C. to 100 ° C. An aqueous solution containing a water-soluble inorganic rust preventive obtained by removing organic matter from rough rinsing wastewater by the apparatus is reused as a rough rinsing liquid. The described cleaning method. 6. A water-soluble inorganic rust preventive which is not adsorbed on activated carbon is silicate, borate, phosphate, nitrite, molybdate, tungstate, and alkali metal hydroxide,
1 selected from the group consisting of carbonates or bicarbonates
The cleaning method according to claim 1, wherein the cleaning method is one or more kinds. 7. The silicate has the general formula xM ₂ O.ySiO ₂ (wherein M represents Na and / or K, and y / x = 0.5).
４4.0. The cleaning method according to claim 6, which is a crystalline silicate and / or a hydrate thereof. 8. A material selected from the group consisting of silicates, borates, phosphates, nitrites, molybdates, tungstates, and alkali metal hydroxides, carbonates or hydrogen carbonates. A rust preventive agent for use in the cleaning method according to claim 5. 9. The silicate has the general formula xM ₂ O.ySiO ₂ (wherein M represents Na and / or K, and y / x = 0.5).
４4.0. 9. The rust preventive agent according to claim 8, which is a crystalline silicate and / or a hydrate thereof.