JP7056952B2 - Cleaning method - Google Patents

Description

The present invention relates to, for example, a method for cleaning processed products such as various machine parts.

Various processing oils are used for processing such as cutting and grinding of machine parts. Of the processing oils, water-soluble processing oils are made by emulsifying mineral oils in water, and are often used because they are not flammable or explosive and have the advantages of being able to wash the processing oils with water.

A water-based cleaning solution such as water is usually used to clean the object to be cleaned to which water-soluble stains based on such water-soluble processing oil are attached. However, since water is difficult to dry, there is a problem that water stains tend to remain. In order to suppress the generation of water stains, Patent Document 1 describes a cleaning step of cleaning an object to be cleaned with a W / O emulsion type hydrocarbon-based cleaning solution containing a specific hydrocarbon, a surfactant and water, and cleaning. After that, a rinse step 1 of rinsing the object to be cleaned with the above-mentioned hydrocarbon-based cleaning solution to remove the W / O type emulsion, and a rinsing step 2 of rinsing the object to be cleaned with the above-mentioned hydrocarbon to remove the hydrocarbon-based cleaning solution. A cleaning system including is proposed.

However, in the cleaning system of Patent Document 1, since a rinsing tank is required to perform the rinsing steps 1 and 2, the number of tanks increases, the entire apparatus becomes large, and the cleaning efficiency is poor. ..

Further, the cleaning system of Patent Document 1 has a problem that the cleaning property against water-soluble stains in blind holes and water-soluble stains obtained by drying and solidifying water-soluble processing oil is not sufficient.

Japanese Unexamined Patent Publication No. 2010-174106

An object of the present invention is to provide a cleaning method capable of improving the cleaning efficiency for water-soluble stains without increasing the number of tanks.

In the cleaning method of the present invention for solving the above problems, the object to be cleaned is immersed in a cleaning solution containing a hydrocarbon solvent, a surfactant and water, and water-soluble stains are emulsified and separated from the object to be cleaned. Steps, a rinsing step of immersing the washed object in a rinse solution of a hydrocarbon solvent and rinsing under ultrasonic irradiation, a drying step of drying the rinsed object to be washed, and a deteriorated rinse used in the rinsing step. It is characterized by including a regeneration step of separating water from the liquid and regenerating the rinse liquid.

According to the present invention, in the cleaning step, water-soluble stains are emulsified and separated from the object to be cleaned, and in the rinsing step, they are rinsed under ultrasonic irradiation. It is possible to improve the cleaning efficiency for dry and hardened water-soluble stains. Therefore, cleaning can be performed without increasing the number of tanks required for the cleaning process and the rinsing process.

It is a block diagram which shows the cleaning apparatus for carrying out the cleaning method which concerns on one Embodiment of this invention.

A cleaning method according to an embodiment of the present invention will be described with reference to FIG. The cleaning device 1 shown in FIG. 1 is a device for use in a cleaning method for removing water-soluble stains (water-soluble processing oil, etc.) adhering to an object to be cleaned, and includes a cleaning tank 2 containing a cleaning liquid and a cleaning tank 2. A rinsing tank 3 containing a rinsing solution of a hydrocarbon solvent and a drying tank 4 are provided, and an object to be washed (not shown) is washed in the order of a washing step, a rinsing step, and a drying step.

The cleaning liquid used in the cleaning step contains a hydrocarbon solvent, a surfactant and water. Examples of the hydrocarbon solvent include saturated aliphatic hydrocarbons having 9 to 14 carbon atoms. Examples of such saturated aliphatic hydrocarbons include n-heptane, n-octane, n-nonane, n-decane, n-undecane, n-dodecane, n-tridecane, n-tetradecane, n-pentadecane and the like. -Isoparaffinic hydrocarbons such as paraffinic hydrocarbons, isoheptane, isooctane, isononan, isodecane, isoundecane, isododecane, isotridecane, isotetradecane, and isopentadecane can be used. These may be used alone or in combination of two or more. In addition, alicyclic hydrocarbons such as 4-methyl-1-isopropylcyclohexane and decalin, aromatic hydrocarbons such as diethylbenzene, diisopropylbenzene and 1-pentylbenzene can also be used as hydrocarbon solvents.

As the surfactant, a nonionic surfactant and / or an anionic surfactant is used.
As the nonionic surfactant, for example, polyalkylene glycols and fatty acid esters can be used. In particular, fatty acid esters can form a stable emulsion when water is added and a physical force is applied, and the detergency can be improved.

Examples of polyalkylene glycols used as nonionic surfactants include polyoxyethylene polyoxypropylene block copolymers and polyoxyethylene polyoxypropylene alkyl ethers.
Examples of the fatty acid esters used as the nonionic surfactant include sorbitan fatty acid esters, ethylene glycol fatty acid esters, glycerin fatty acid esters, propylene glycol fatty acid esters, polyoxy fatty acid esters and the like. The nonionic surfactant can be used alone or in admixture of two or more, and has an HLB value (hydrophilic lipophilic balance value) of 1 or more, preferably 3 to 10, and is used in the present invention. It is preferable to use a solvent that can be dissolved in a hydrocarbon solvent and does not gel when water is added and physical force is applied.

As the anionic surfactant, for example, petroleum sulfonate, sulfonates such as funnel oil, sulfate ester salts, carboxylates and the like can be used. As the sulfonate, a hydrocarbon sulfonate having 8 to 22 carbon atoms is preferable. Examples of the sulfate ester salt include sulfated oil having 8 to 18 carbon atoms and an alkyl sulfate ester salt having 8 to 18 carbon atoms. Examples of the carboxylate include a dialkyl sulfosuccinic acid ester salt having 6 to 13 carbon atoms in an alkyl group, an alkyl sulfosuccinate dihydrate having 6 to 13 carbon atoms, and a polyoxyethylene alkyl sulfosuccinate having 6 to 13 carbon atoms in an alkyl group. Acid disalt and the like can be mentioned.
Examples of the salt of the anionic surfactant include an alkali metal salt, an alkaline earth metal salt, an ammonium salt, an alkanolamine salt having 1 to 5 carbon atoms, and the like, and an acid such as a sulfonic acid, a sulfate ester, or a carboxylic acid. The form of is also available. The anionic surfactant exemplified above may be used alone or in combination of two or more.

The blending amount of the surfactant is 0.5 to 10% by mass, preferably 1 to 3% by mass, based on the total amount of the cleaning liquid. The blending amount of water is 1 to 30% by mass, preferably 5 to 20% by mass, based on the total amount of the cleaning liquid.

The cleaning liquid thus obtained is preferably an emulsion that is relatively unstable in a static state and is easily phase-separated between a hydrocarbon solvent and water. Since the cleaning liquid is easily phase-separated in this way, the rinsing liquid can be easily regenerated by separating the aqueous phase containing water-soluble stains.

In the present embodiment, physical forces such as ultrasonic waves, rocking, and spraying are applied to such an unstable cleaning liquid, and the circulation pump 8 provided in the cleaning tank 2 forcibly circulates the unstable cleaning liquid, so to speak. W / O emulsion is formed. As a result, the water-soluble stains adhering to the surface of the object to be cleaned can be emulsified and removed from the surface of the object to be cleaned.

In order to make the cleaning liquid into a relatively unstable emulsion, for example, the type and blending amount of the surfactant may be adjusted. That is, the surfactant may be of a type and blending amount such that the hydrocarbon solvent of the cleaning liquid and water can be easily phase-separated.

After cleaning, the object to be cleaned is immersed in a rinsing solution of a hydrocarbon solvent for rinsing. As the hydrocarbon solvent, a hydrocarbon solvent constituting the above-mentioned cleaning liquid can be used. That is, the hydrocarbon solvent constituting the rinsing solution may be the same as the hydrocarbon solvent constituting the cleaning solution, or is a hydrocarbon solvent having a lower boiling point than the hydrocarbon solvent constituting the cleaning solution. May be good.
By performing the rinsing step, water-soluble stains adhering to and remaining on the surface of the object to be cleaned can be removed together with water and a surfactant.

In the rinsing step, it is preferable to perform rinsing under ultrasonic irradiation in order to improve the cleaning effect. Therefore, the ultrasonic vibrator (US) 6 is installed in the rinse tank 3 in the present embodiment. This makes it possible to remove the water-soluble stains in the blind holes remaining in the object to be cleaned and the water-soluble stains obtained by drying the water-soluble processing oil.

That is, when the object to be cleaned is immersed in the above-mentioned rinsing liquid and sufficiently rinsed by ultrasonic irradiation, the aqueous phase composed of water and water-soluble stain components descends in the form of granules. Open the valve 7 and discharge.

After rinsing, the object to be washed is sent to the drying tank 4 and a drying step is performed. In the drying step, the object to be cleaned is first steam-washed and then dried under reduced pressure or normal pressure. In steam cleaning, the same hydrocarbon solvent as the hydrocarbon rinsing liquid is used. As this hydrocarbon solvent, one regenerated in the regeneration step described later can be used.

On the other hand, the deteriorated rinsing liquid in the rinsing tank 3 is slightly mixed with a small amount of water, a surfactant, and a water-soluble stain component. Moreover, since water is finely dispersed, it is difficult to separate it from the rinsing liquid. Therefore, the deteriorated rinsing liquid in the rinsing tank 3 is sent to the regeneration step, and is regenerated by removing a trace amount of water, a surfactant, and a water-soluble stain component.

The deteriorated rinse liquid extracted from the rinse tank 3 by the liquid feed pump 9 is first sent to the filter case 10 as a pretreatment, and foreign substances such as metal particles are removed. The deteriorated rinse liquid that has passed through the filter case 10 is sent to the oil-water separation device 11.

The oil-water separation device 11 has a cylindrical oil-water separation filter 12 installed therein, and the deteriorated rinsing liquid is introduced into the oil-water separation filter 12 and passes through the oil-water separation filter 12 constituting the peripheral wall. The oil-water separation filter 12 is made of an ultrafine non-woven fabric having a pore size of about 1 to 10 μm, and has a function of capturing finely dispersed water droplets, aggregating them, and coarsening them when the deteriorated rinsing liquid passes through the oil-water separation filter 12. Has. The coarsened water droplets are immediately separated from the hydrocarbon solvent constituting the rinsing liquid due to the difference in specific gravity, and settle to the bottom. At that time, the surfactant adhering to water is also separated from the hydrocarbon solvent at the same time.
Examples of the oil-water separation filter 12 include an oil-water separation filter manufactured by Asahi Kasei Corporation, and EUS15BV, EUS12BV and the like manufactured by the same company can be used.

The rinse liquid from which water has been separated is sent out from the upper part of the oil-water separation device 11. On the other hand, the separated aqueous phase W is taken out by opening the discharge valve 20 from the lower part of the oil-water separation device 11.

The rinse liquid sent out from the oil-water separation device 11 is sent to the storage tank 13. The rinse liquid is further separated into oil and water by the demister 14 installed in the storage tank 13, and the aqueous phase separated at the bottom is extracted by opening the discharge valve 15, and the oil phase, that is, the hydrocarbon constituting the rinse liquid is carbonized. The hydrocarbon solvent is stored in the storage tank 13.

Since the water content of the rinse liquid stored in the storage tank 13 is reduced to about 0.01% by mass or less, it may be returned to the rinse tank 3 as it is through the conduit 16 or remains in the rinse liquid. It may be sent to the distiller 17 in order to remove oil such as water-soluble processing oil. These controls can be performed by the three-way valve 18.

Since the hydrocarbon solvent constituting the rinsing liquid has a lower boiling point than the oil content of the water-soluble processing oil or the like, the oil content such as the water-soluble processing oil can be removed from the rinsing liquid by the distiller 17. The regenerated rinse liquid is sent out from the upper part of the distiller 17, and a part of the rinse liquid is sent to the drying tank 4 for steam cleaning of the object to be cleaned. Further, the rest of the rinsing liquid is sent to the rinsing tank 3 by switching the three-way valve 19. A condenser (not shown) may be interposed between the three-way valve 19 and the rinsing tank 3 to send the rinsing liquid in a liquid state to the rinsing tank 3.

Although the cleaning method according to the embodiment of the present invention has been described above, the cleaning method of the present invention is not limited to the above embodiment. For example, in the regeneration step, the filter case 10 may be installed as needed, and the deteriorated rinsing liquid may be sent directly to the oil-water separation device 11. Further, the storage tank 13 may be installed as needed, and the oil-water separation device 11 and the distiller 17 may be connected without going through the storage tank 13.

1 Cleaning device 2 Cleaning tank 3 Rinse tank 4 Drying tank 5, 6 Ultrasonic oscillator 7 Discharge valve 8 Circulation pump 9 Liquid feed pump 10 Filter case 11 Oil / water separation device 12 Oil / water separation filter 13 Storage tank 14 Demister 15 Discharge valve 16 pipes Road 17 Distiller 18, 19 Three-way valve 20 Discharge valve W Water phase

Claims (3)

A cleaning step of immersing the object to be cleaned in a cleaning solution containing a hydrocarbon solvent, a surfactant, and water to emulsify and separate water-soluble stains from the object to be cleaned.
A rinsing step in which the object to be washed after cleaning is immersed in a rinsing solution of a hydrocarbon solvent and rinsed under ultrasonic irradiation.
A drying step in which the rinsed object to be washed is steam-washed with the same hydrocarbon solvent as the rinse solution and then dried.
It comprises a regeneration step of separating water from the deteriorated rinse solution used in the rinse step and then distilling to regenerate the rinse solution .
The rinse liquid in a gaseous state distilled in the regeneration step is partially used for steam cleaning of the object to be cleaned in the drying step, and the rest of the rinse liquid is sent to the rinse step . Cleaning method. The cleaning method according to claim 1, wherein in the regeneration step, water is separated from the deteriorated rinse liquid by an oil-water separation filter, and then the rinse liquid is distilled and regenerated. The cleaning method according to claim 1 or 2, wherein in the cleaning step, a physical force is applied so that the cleaning liquid is not separated into the hydrocarbon solvent and water.

Images