JP2816805B2 - Cleaning method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to electronic parts and precision parts to which dirt such as oils and fats, machine oils, cutting oils, greases, waxes, liquid crystals and fluxes are adhered, or jigs and tools used for assembling and processing these parts. More specifically, the present invention relates to a cleaning method that is excellent in the processability of a cleaning liquid after cleaning in a cleaning step and the maintenance of the cleaning property in the cleaning step.

[0002]

2. Description of the Related Art
To remove dirt mainly on organic substances such as oils and fats, machine oils, cutting oils, greases, waxes, liquid crystals, and fluxes present on solid surfaces such as precision parts and jigs, use hydrocarbons such as kerosene, benzene, and xylene. Solvents: Chlorinated solvents such as trichloroethylene and tetrachloroethylene; Freon-based solvents such as trichlorotrifluoroethane; aqueous cleaning agents containing a surfactant and a builder are used. In particular, fluorocarbon-based solvents or chlorine-based solvents have been used for components such as electronics, electricity, and machines, taking advantage of their high detergency and flame retardancy.

[0003] However, a detergent using a chlorofluorocarbon-based or chlorine-based solvent has serious problems in safety, toxicity, environmental pollution and the like. In addition, hydrocarbon solvents, especially benzene and xylene, are highly toxic and are designated as hazardous substances under the Industrial Safety and Health Act.Considering the danger and complexity of handling these substances, cleaning agents Is not preferred.

[0004] On the other hand, aqueous detergents are less dangerous and less toxic than solvent-based detergents, and also have excellent detergency by appropriately selecting detergent components such as surfactants and builders. Can be made. However, in this water-based cleaning agent, when the cleaning component excluding water is washed at, for example, 70% or more, the cleaning liquid adheres to the cleaning agent, and the amount of the cleaning liquid taken out in the rinsing step increases. There is a disadvantage that replenishment is required. In addition, even when used after dilution with water, since the solubility in water is generally good, it is not easy to maintain and manage the cleaning properties of the cleaning liquid, and it is necessary to supply an excessive amount of cleaning agent to secure the cleaning properties. Further, there is a disadvantage that the drainage treatment of the cleaning liquid after the cleaning is extremely poor. The treatment can be performed using, for example, coagulation sedimentation, pressure flotation, activated sludge, activated carbon treatment, or the like, but any treatment requires a great deal of cost and equipment.

[0005] Accordingly, electronic parts or precision parts, etc., which do not require such a large processing cost and equipment, are easy to maintain and control the cleaning properties of the cleaning liquid, and are economically excellent in the amount of cleaning agent used. There has been a demand for a method of cleaning the garment.

[0006]

Under these circumstances, the present inventors have conducted intensive studies, and as a result, by using a water diluent of a specific cleaning agent and applying mechanical force or the like at a temperature of 20 to 100 ° C. If it is kept in a uniform state that does not separate, it has sufficient detergency, and it can easily separate and remove oily stains in the cleaning solution after cleaning and organic substances such as active ingredients in the cleaning agent, resulting in remarkable drainage treatment. It has been found that the cleaning liquid after being improved and separated and removed can be reused. That is, since the organic matter in the cleaning solution after washing can be efficiently separated and removed at a high concentration, the total amount of organic matter discharged per unit time separated and removed from the washing solution after washing is detected, and By replenishing the washing solution with an active ingredient in an amount corresponding to the ratio of active ingredients in all organic substances necessary to maintain at least the washing property of the washing solution, and circulating and using the aqueous phase after the separation treatment, The present inventors have found that the concentration of the detergent can be maintained at a constant level, and the detergency of the cleaning solution can be maintained, thereby completing the present invention.

That is, the gist of the present invention is as follows: (1) In a cleaning method for cleaning electronic parts or precision parts with a cleaning agent, a water dilution of a cleaning agent having the following active ingredients and properties is used. A step of washing at a temperature of 0 ° C. without phase separation (hereinafter abbreviated as a washing step), and a step of separating organic substances in the washing liquid while keeping the washed washing liquid at 20 ° C. or higher (hereinafter abbreviated as a separation step). A method for cleaning electronic parts or precision parts, characterized by having the following: Active component: Nonionic surfactant alone or in addition to nonionic surfactant, linear or branched chain having 6 to 30 carbon atoms A saturated or unsaturated hydrocarbon compound having 6 to 40 carbon atoms
Combination with at least one compound selected from the group consisting of alkyl esters and alkyl ketones having 6 to 40 carbon atoms Properties: The cleaning agent is diluted with water or water is evaporated to reduce the content of the active ingredient. 20 to 100% by weight aqueous solution
The property that 30% by weight or more of the contained active ingredient is separated from the aqueous phase when allowed to stand at a temperature of 30 ° C. for 30 minutes. (2) The inorganic salt in the detergent is 0.1% or less. (3) The washing method described in (1), (3) The remaining aqueous phase obtained by separating and removing organic substances from the washing liquid after washing is reused for diluting the washing agent (1) or (2). And (4) the amount corresponding to the active ingredient ratio in the total organic matter necessary to detect at least the amount of discharged organic substances separated and removed from the washing liquid after washing and to maintain at least the washing property of the washing liquid. (3) The washing method of (3), characterized in that the active component of (1) is supplied to the washing liquid and the aqueous phase after the separation treatment is circulated and used. (5) Oil and fat, machine oil, cutting oil, grease, wax, liquid crystal, and flux It is characterized by cleaning attached electronic parts or precision parts. (1) The cleaning method according to any one of (1) to (4).

[0008] The detergent used in the washing step in the present invention has the following active ingredients and properties. (1) Active ingredient: nonionic surfactant, linear or branched saturated or unsaturated hydrocarbon compound having 6 to 30 carbon atoms, alkyl ester having 6 to 40 carbon atoms, and 6 to 30 carbon atoms. One or more compounds selected from the group consisting of 40 alkyl ketones (2) Properties: 20 to 1 aqueous solution in which the detergent is diluted with water or water is evaporated to make the content of the active ingredient 10% by weight.
The property that 30% by weight or more of the contained active ingredient is separated from the aqueous phase when left at a temperature of 00 ° C. for 30 minutes.

The detergent used here is not particularly limited as long as it has the above-mentioned active ingredients and properties. That is, as the active ingredient, a nonionic surfactant is an essential component, and the nonionic surfactant may be used alone or in addition to the nonionic surfactant, a linear or branched chain having 6 to 30 carbon atoms. A saturated or unsaturated hydrocarbon compound, an alkyl ester having 6 to 40 carbon atoms,
And at least one compound selected from the group consisting of alkyl ketones having 6 to 40 carbon atoms.

For example, a nonionic surfactant having a cloud point of 100 ° C. or lower, a hydrocarbon compound used for improving detergency against oily stains, poorly water-soluble alkyl esters and alkyl ketones And the like,
A detergent containing 50% by weight or more of the organic component in the detergent composition is exemplified. Of these, in order to particularly enhance the detergency, these components are used as 70% of the organic components in the detergent composition.
More preferably, the content is not less than 10% by weight. Here, the cloud point means that when 10 to 30 ml of the detergent composition diluted 20 times with ion-exchanged water is placed in a test tube and the temperature is raised at a rate of 1 ° C./min, the liquid becomes turbid. The temperature at which the solution is discharged. When the temperature is maintained at or above this temperature, the nonionic surfactant in the aqueous solution gradually separates from the aqueous phase.

Examples of the nonionic surfactant include ether types such as alkyl ether type, alkyl allyl ether type and alkyl thioether type; ester types such as alkyl ester type and sorbitan alkyl ester type; polyoxyalkylene alkylamines and the like. Condensed forms with amines; Condensed forms with amides such as polyoxyalkylene alkyl amides; Pluronic or tetronic forms obtained by random or block condensation of polyoxyethylene and polyoxypropylene; Surfactants such as polyethyleneimine series . Among them, those having a hydrocarbon group having 4 to 22 carbon atoms are particularly preferable, and a detergent composition containing such a nonionic surfactant has an increased affinity for oily stains and thus has a higher detergency. Along with the improvement, the cleaning solution after cleaning containing this tends to show a clear cloud point,
The wastewater treatment property is particularly good.

Examples of the hydrocarbon compound include, for example, paraffins, olefins, or aromatic or aliphatic liquids having a linear or branched saturated or unsaturated bond having 6 to 30 carbon atoms which are liquid at the temperature of the washing step. A hydrocarbon compound containing a ring is exemplified. Further, as the alkyl esters, for example, carbon atoms having 6 to 40 carbon atoms which are liquid at the temperature of the washing step.
Monoesters, diesters, and triesters, especially higher fatty acids having 6 to 18 carbon atoms and 1 to 18 carbon atoms.
Ester of a higher alcohol having 6 to 18 carbon atoms and a diol or triol having 2 to 8 carbon atoms; higher alcohol having 1 to 18 carbon atoms and 2 to 8 carbon atoms
Esters with dicarboxylic acids or tricarboxylic acids are preferred. As the alkyl ketones, dialkyl ketones having 6 to 40 carbon atoms are preferable.

The detergent composition contains, in addition to these components, a surfactant such as anionic, amines such as alkanolamine, a builder, a chelating agent, a rust preventive, an antifoaming agent and the like, if necessary. It is also possible to use those that do.

In the above-mentioned properties of the cleaning agent of the present invention, if the amount of the active ingredient separated from the aqueous phase is less than 30% by weight, the active ingredient is not sufficiently separated from the washing liquid after washing, and as a result, oil stains And other organic soil components are easily dissolved, emulsified, and dispersed in the aqueous phase, and the drainage treatment property is not sufficiently improved. Further, even if the aqueous phase after the separation treatment is reused as a diluting liquid for the cleaning liquid, the content of organic substances such as oil stains is large, causing recontamination of the cleaning liquid, and the maintenance of the cleaning performance is significantly reduced. For this reason, in order to more effectively improve the wastewater treatment property and to enable the reuse of the cleaning solution after the cleaning, a cleaning agent that separates 70% by weight or more of the contained active ingredient is used. Is preferred. Here, the amount of the active ingredient separated from the aqueous phase is measured by COD or TOC (total organic carbon).

In the electronic parts or precision parts to be cleaned in the present invention, caustic soda, sodium orthosilicate, sodium carbonate or phosphorus contained in the cleaning agent is used in view of safety and electrical reliability of the members. 1% or less, preferably 0.1% or less of inorganic salts such as sodium acid
% Is desirable .

Although the washing step in the present invention is not particularly limited, a temperature of 20 to 100 ° C., preferably 20 to 70 ° C., using a detergent composition having the above-mentioned active ingredients and properties is used. In order to maintain a state in which the cleaning liquid does not undergo phase separation in the temperature range of, for example, circulating and stirring with a stirring blade or a pump or the like, an immersion method, an ultrasonic cleaning method, an oscillating method, a spray method, or the like may be performed alone or in combination. it can.

In the step of separating the washing solution after washing, the washing solution after washing is kept at 20 to 100 ° C., preferably 20 to 7 ° C.
By heating or cooling to 0 ° C., the organic matter in the cleaning solution is separated and removed while keeping the temperature at 20 ° C. or higher. Here, the organic matter includes those containing the active component and various organic soil components in the separated detergent. In order to heat the cleaning liquid to 100 ° C. or higher, equipment such as pressurization is required, which is not practically useful. In addition, to lower the temperature to less than 20 ° C., cooling equipment or the like must be installed in summer or the like, Not practical. In particular, it is preferable to heat the nonionic surfactant to a temperature higher than the cloud point of the nonionic surfactant since separation can be performed more effectively. That is, when the temperature becomes higher than the cloud point, the nonionic surfactant loses water solubility, and as a result, the oily stain that has been solubilized or emulsified in the washing liquid cannot be retained in water, and the oily stain is Floating or sinking in water separates depending on the specific gravity. Further, the nonionic surfactant itself loses water solubility and separates from water.

The separated organic matter is composed of, for example, an active ingredient such as a nonionic surfactant and a hydrocarbon compound and an oily dirt component. The removal of such organic matter is performed by receiving a washing liquid after washing or by separating the organic solvent. In a dedicated tank for the above, while maintaining at 20 ℃ or more, preferably 20 to 70 ℃, skimming method, method using a separation membrane, centrifugation method, electrical separation method etc. alone or in combination of two or more Can be done.

Since the washing liquid after washing is purified by efficiently separating the organic matter in this manner, the remaining aqueous phase obtained by separating and removing the organic matter from the washing liquid is reused for diluting the washing agent. Can be. Upon reuse, if necessary, an ion exchange treatment or an adsorption treatment with activated carbon may be performed to remove organic substances such as water-soluble ions and surfactants in the cleaning liquid.

Also, in the present invention, since organic substances can be efficiently separated at a high concentration,
All the cleaning liquids after the cleaning can be collectively separated and reused in a batch system. Alternatively, a part of the washing liquid after the washing is subjected to a separation treatment, the amount of discharged organic substances separated and removed from the washing liquid is detected, and the ratio of the active ingredient in the whole organic substances necessary to maintain at least the washing property of the washing liquid is detected. By replenishing the washing solution with a certain amount of the active ingredient and circulating and using the aqueous phase after the separation treatment, the washing property of the washing solution can be maintained continuously. Here, the total organic matter discharge amount refers to the discharge amount of all organic substances including the active components and various organic soil components in the separated detergent. The measurement of the discharge amount can be performed by weight or volume measurement.
Further, the ratio of the active ingredient in the total organic matter necessary for maintaining at least the washing property of the washing liquid is the minimum weight of the active ingredient necessary for maintaining the washing property with respect to the weight or volume of the soil component and the active ingredient. Or it means the ratio of the volumes.

Further, if necessary, two or more of the present systems may be used in combination, or may be used in combination with another cleaning system which is usually performed. Further, a rinsing (rinsing) step may be provided if necessary, and examples thereof include a rinsing method described in JP-A-4-12480 and JP-A-5-96255.

The cleaning method of the present invention has a particularly excellent effect when cleaning precision parts and jigs and the like used in the assembling process. Here, precision parts include, for example, electronic parts, electric parts, Precision machine parts, resin processed parts, optical parts, etc. Electronic components include, for example, printed wiring boards used in computers and their peripheral devices, home appliances, communication devices, OA devices, and other electronic devices; used in contact members such as IC lead frames, resistors, capacitors, and relays. Hoop material; Liquid crystal display used for OA equipment, clocks, computer equipment, toys, home appliances, etc .; Magnetic recording parts used for video / audio recording / reproduction parts and related parts; Semiconductors such as silicon and ceramic wafers Materials; electrostrictive components such as quartz oscillators; and photoelectric conversion components used for CDs, PDs, copying machines, optical recording devices, and the like. The electric components include, for example, electric motor components such as brushes, rotors, stators, and housings; ticketing components used in vending machines and various devices; and currency inspection components used in vending machines, cash dispensers, and the like. Precision equipment parts include, for example, bearings used in precision drive equipment, video recorders, and the like; machining parts such as carbide chips, and the like. The resin processed parts refer to precision resin processed parts used for cameras, automobiles, and the like, for example. Further, the optical component refers to, for example, a lens used for a camera, eyeglasses, an optical device, and the like, and the other component includes, for example, an eyeglass frame, a watch case, a watch belt, and the like. In addition, jigs and tools used in the assembling process include, in addition to jigs and tools used in various processes such as manufacturing, molding, processing, assembling, and finishing precision components as shown in the above-described various component examples, It refers to various devices that handle these precision parts and their parts.

The cleaning method of the present invention exhibits a suitable performance particularly when cleaning wax such as liquid crystal or rosin-containing wax adhering to a printed wiring board or a glass substrate in which flux remains. The precision parts and jigs and tools which are the objects of the present invention are not limited to these examples. The cleaning method of the present invention can be applied to precision parts and jigs having a solid surface of a certain shape to which various oily contaminants to be adhered are attached. When these contaminants are mainly organic oil stains such as oils and fats, machine oils, cutting oils, greases, liquid crystals, and rosin-based fluxes, the characteristics of the cleaning method of the present invention are particularly exhibited. Further, the present invention is effective even for dirt mixed with metal powder, inorganic powder, and the like.

[0024]

Next, the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples.

Example 1 A detergent composition having the composition shown in Table 1 was prepared, and diluted with ion-exchanged water so that the active ingredient content became 10% by weight. Let stand at temperature for 30 minutes. As a result, the cleaning composition No. In all of Examples 1 to 4, it was confirmed that 30% by weight or more of the contained active ingredient was separated from the aqueous phase (85, 7 respectively).
3, 70, 80%). On the other hand, in cleaning compositions 5 and 6, 0
%, 10%. The amount of the active ingredient separated from the aqueous phase was measured by COD.

Next, a printed circuit board (10 cm × 15 cm) [test material 1] treated with a rosin-based flux using a 10-fold water dilution of the cleaning composition shown in Table 1 and a naphthenic mineral oil (40 ° C., 350 cSt) ) Is applied (1 g / m
² ) The test piece made of steel (10 cm × 15 cm) [test material 2] and the glass substrate (10 cm × 10 cm) coated with liquid crystal (5 g / m ² ) [test material 3] were washed.
Washing was performed at 50 ° C. for 3 minutes by ultrasonic washing while stirring with a stirring blade to prevent phase separation. Each of the washed plates (test materials 1 to 3) after washing was immersed in ion-exchanged water at 40 ° C., and rinsed (rinsed) while applying ultrasonic waves for 1 minute. The appearance of the rinsed plates (test materials 1 to 3) after rinsing was all good.

Next, the used washing solution is taken in a beaker, kept at 50 ° C., and stirred at 2 L / M while stirring so as not to separate phases under the same conditions as the washing described above (cross sectional area: 36).
6 cm ² ), return the lower layer solution to the beaker again, sample the cleaning liquid after circulating for 30 minutes, measure its COD (chemical oxygen demand) (A value), and measure the COD (B value) of the cleaning liquid before the processing. ), And the organic matter separation ratio ((B value−A value) ÷ B value) × 100 was calculated. Next, using the aqueous phase after the circulation treatment for 30 minutes, each detergent composition was diluted 10-fold, washed and rinsed under the same conditions as above, and the removability of dirt substances at that time was evaluated. Table 1 shows the results. The evaluation criteria for the removability of the contaminants are as follows.

Evaluation criteria for removal of soiling substances: A; Soiling substances (flux, naphthenic mineral oil or liquid crystal)
Very good with no residue. ；: Good with almost no residual dirt. Δ: Slight residue of dirt substance was slight and slightly poor.

[0029]

[Table 1]

As is evident from the results in Table 1, even under the stirring conditions having good detergency, the detergent compositions 1 to 4 have a high organic matter separation rate and a cleaning liquid obtained by separation. Was low in COD, so it was recognized that there was little organic matter. In addition, those having a separation rate of 50% or more (detergent composition 1
-4) showed good detergency even when the aqueous phase was reused for diluting the detergent, and those having a separation rate of 80% or more (detergent compositions Nos. 1, 2 and 4) were excellent. .

[0031]

According to the present invention, organic substances in the cleaning solution after cleaning can be efficiently separated and removed at a high concentration, and the subsequent wastewater treatment process can be simplified.
Electronic components or precision components to which dirt such as cutting oil, grease, wax, liquid crystal, and flux adhere can be industrially advantageously cleaned. Further, the aqueous phase separated and treated according to the present invention can be used again for diluting the detergent, and the amount of water used for diluting the detergent can be greatly reduced, and the total organic matter discharged and removed. By replenishing a certain percentage of the active ingredient, the cleaning properties of the cleaning liquid can be maintained, the amount of the cleaning agent used can be reduced, and it is economically excellent.

Continuation of front page (56) References JP-A-50-650 (JP, A) JP-A-48-5256 (JP, A) JP-A-4-122480 (JP, A) JP-A-4-68097 (JP) JP-A-2-63503 (JP, A) JP-A-1-210004 (JP, A) JP-A-58-34182 (JP, A) JP-A-55-47104 (JP, A) 52-135844 (JP, A) JP-A-50-56744 (JP, A) JP-B-7-22650 (JP, B2) JP-B-56-15792 (JP, B2) Patent 2610552 (JP, B2) Patent 2539284 (JP, B2) (58) Fields investigated (Int. Cl. ⁶ , DB name) B08B 3/00-3/12 C23G 5/00-5/04 B01D 17/06 C01F 1/46

Claims (5)

(57) [Claims] 1. A cleaning method for cleaning electronic parts or precision parts with a cleaning agent using a water diluent of a cleaning agent having the following active ingredients and properties so that no phase separation occurs at a temperature of 20 to 100 ° C. Cleaning the electronic component or the precision component, comprising a step of separating the organic matter in the cleaning liquid while keeping the cleaning liquid after the cleaning at 20 ° C. or higher. Active ingredient: Nonionic surfactant alone or in addition to a nonionic surfactant, a linear or branched saturated or unsaturated hydrocarbon compound having 6 to 30 carbon atoms, 6 to 40 carbon atoms
Combination with at least one compound selected from the group consisting of alkyl esters and alkyl ketones having 6 to 40 carbon atoms Properties: The cleaning agent is diluted with water or water is evaporated to reduce the content of the active ingredient. 20 to 100% by weight aqueous solution
The property that 30% by weight or more of the contained active ingredient separates from the aqueous phase when allowed to stand at 30 ° C for 30 minutes. 2. The cleaning method according to claim 1, wherein the content of the inorganic salts in the cleaning agent is 0.1% or less. 3. The cleaning method according to claim 1, wherein the remaining aqueous phase obtained by separating and removing organic substances from the cleaning liquid after the cleaning is reused for diluting the cleaning agent. 4. A method for detecting an amount of discharged organic substances separated and removed from a washing solution after washing, and extracting an amount of active ingredients corresponding to a ratio of active ingredients in the total organic substances necessary for maintaining at least the washing property of the washing liquid. 4. The cleaning method according to claim 3, wherein the aqueous phase after the separation treatment is recycled by supplying to the cleaning liquid. 5. The cleaning method according to claim 1, wherein the electronic parts or precision parts to which the oils and fats, the machine oil, the cutting oil, the grease, the wax, the liquid crystal, and the flux are adhered are washed. .