JP2816928B2 - 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. (Hereinafter referred to as electronic parts or precision parts), and more particularly, to a cleaning method excellent in the treatment of rinse drainage generated in a rinsing 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, since this water-based cleaning agent generally has good solubility in water, a rinsing solution after rinsing (rinsing) the cleaning solution attached to the material to be cleaned with a water-based rinsing solution (hereinafter referred to as rinsing drainage). ) Has the disadvantage that the wastewater treatment property 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, there has been a demand for a method for industrially and advantageously cleaning electronic parts or precision parts without requiring such a large processing cost and equipment.

[0006]

Means for Solving the Problems Under such circumstances, the present inventors have conducted intensive studies and as a result, after cleaning with a specific cleaning agent, rinsing with 5-100 ° C. water, If a voltage is applied while maintaining the temperature at 20 ° C. or higher, organic substances such as oily stains and cleaning agents in the rinse drainage can be easily separated and removed, and as a result, the drainage treatment property is significantly improved,
Furthermore, they found that the rinse solution after separation and removal could be reused, and completed the present invention.

That is, the present invention provides a cleaning method for cleaning an electronic component or precision components with a cleaning agent (hereinafter referred to as a cleaning step) and then rinsing with water (hereinafter referred to as a rinsing step). As a component, it contains a compound selected from a nonionic surfactant and / or a hydrocarbon compound, a poorly water-soluble alkyl ester and an alkyl ketone, and dilutes the detergent with water or evaporates the water. When the content of organic substances is set to 10% by weight (hereinafter simply referred to as%) and the detergent aqueous solution is allowed to stand at a temperature of 20 to 100 ° C. for 30 minutes, 30% or more of the organic substances contained are separated from the aqueous phase. Using a cleaning composition having the property of separating, using water at 5 to 100 ° C. as a rinsing liquid, applying a voltage while maintaining the rinse drainage after rinsing at 20 ° C. or higher, and applying an organic substance from the rinse drainage. Isolate (Hereinafter, referred to as the separation step) is to provide a cleaning method of the electronic component or precision parts such that said.

In the present invention, the detergent composition used in the washing step comprises a nonionic surfactant and / or a hydrocarbon compound and a sparingly water-soluble alkyl ester and alkyl ketone as active ingredients of the detergent. And the detergent is diluted with water or the water is evaporated to reduce the content of organic substances to 10%, and the detergent aqueous solution is used.
When allowed to stand at a temperature of 20 to 100 ° C. for 30 minutes, 30% or more of the contained organic matter is separated from the aqueous phase. If the organic matter to be separated is less than 30%, the cleaning agent component is not sufficiently separated from the rinse drainage after rinsing, and as a result, organic soil components such as oil stains are dissolved, emulsified and dispersed in the aqueous phase. In addition, the wastewater treatment property is not sufficiently improved, and even if the aqueous phase after the separation treatment is reused as a rinsing liquid, the organic matter content is large and the rinsing effect is significantly reduced. In order to improve wastewater treatment more effectively and enable reuse of rinsing liquid,
It is preferable to use a cleaning agent that separates 70% or more of the contained organic matter.

The cleaning composition used here includes:
Although it is not particularly limited as long as it has the above characteristics and has satisfactory detergency, for example, it has a cloud point of 1
A compound selected from hydrocarbon compounds, poorly water-soluble alkyl esters and alkyl ketones used for improving the detergency of nonionic surfactants and / or oily stains having a temperature of 00 ° C. or lower is washed. 50 of the organic components of the agent
% Or more. Among these, those containing 70% or more of the organic components of the detergent are more preferable, particularly for improving the rinsing property. 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 has a higher detergency. In addition to the improvement, the rinse drainage after rinsing in which it is mixed tends to show a clear cloud point, and the drainage treatment property is particularly good.

Examples of the hydrocarbon compound include paraffins, olefins, and aromatics having a linear or branched saturated or unsaturated bond having 6 to 30 carbon atoms which are liquid at the temperature of the washing or rinsing step. And hydrocarbon compounds containing an alicyclic group. Further, examples of the alkyl esters include monoesters, diesters, and triesters having 6 to 40 carbon atoms which are liquid at the temperature of the washing or rinsing step. Particularly, higher fatty acids having 6 to 18 carbon atoms and 1 to 1 carbon atoms are preferred. Esters of higher alcohols having 18 carbon atoms; esters of higher fatty acids having 6 to 18 carbon atoms and diols or triols having 2 to 8 carbon atoms; higher alcohols having 1 to 18 carbon atoms and 2 carbon atoms
Esters with dicarboxylic acids or tricarboxylic acids of ~ 8 are preferred. As the alkyl ketones, dialkyl ketones having 6 to 40 carbon atoms are preferable. As a cleaning composition,
In addition to these components, those containing a surfactant such as an anionic surfactant, a builder, a chelating agent, a rust inhibitor, an antifoaming agent, and the like can be used as necessary.

Although the washing step is not particularly limited, for example, an immersion method, an ultrasonic cleaning method, an oscillating method, a spray method or the like can be performed alone or in combination.

The rinsing liquid used in the rinsing step is a liquid for rinsing a cleaning liquid containing a stain and / or a cleaning composition on a material to be cleaned, and more specifically, pure water for cleaning. However, from the viewpoint of wastewater treatment, it is preferable to circulate and use the liquid after separating and removing organic substances from the rinse wastewater.

The rinsing is carried out by using a rinsing liquid at 5 to 100 ° C., for example, by a dipping method, an ultrasonic cleaning method, a oscillating method, a spray method or the like. Rinse liquid temperature is 5-100
° C, preferably 20-70 ° C. A temperature outside this range is not preferred because the cost, equipment, etc., required for heating, cooling, etc. of the rinsing liquid increase.

In the rinsing drain separation step, the rinse drain after rinsing is subjected to a temperature of 20 to 100 ° C., preferably 20 to 70 ° C.
Heat or cool to ° C. to separate and remove organics. Heating the rinse liquid to 100 ° C or higher requires equipment such as pressurization, which is not practically useful.To reduce the temperature to less than 20 ° C, cooling equipment must be installed in summer, etc. Not practically effective. In particular, when a detergent composition containing a nonionic surfactant is used, 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 solubilized or emulsified in the rinsing liquid cannot be held in water, and the oily stain Floats and sinks in water depending on the specific gravity, and separates. Further, the nonionic surfactant itself loses water solubility and separates from water.

The removal of the organic substances thus separated, for example, nonionic surfactants, hydrocarbon compounds, oily dirt components, etc., is performed by rinsing the rinsing liquid in a rinsing liquid receiving tank or a dedicated tank for separation. This is performed by applying a voltage to the liquid while maintaining the liquid at 20 ° C. or higher. The organic matter in the rinse waste liquid whose solubility has been reduced by keeping the temperature at 20 ° C. or higher becomes easier to unite by applying a voltage,
Separation from the aqueous phase is faster and more efficient than when no voltage is applied. In the present invention, it is particularly preferable to use a separation device that can directly immerse the electrodes in the rinse drainage and apply an AC voltage between the electrodes in terms of separation speed and separation efficiency. In the present invention, the applied voltage is 10 to 50.
0 V is preferable, and the application time of 20 minutes or less is sufficient. In the separation of organic substances, if necessary, a separation apparatus such as a skimming method, a method using a separation membrane, and a centrifugal separation method, which are usually used, may be provided in a dedicated tank and used. By performing the separation efficiently in this manner, the rinse waste liquid is purified, and can be reused as a rinse liquid, that is, can be recycled. In circulating use, if necessary, treatment such as ion exchange treatment, adsorption treatment with activated carbon, or membrane separation may be performed to remove organic substances such as water-soluble ions and surfactants in the rinse solution.

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 especially when cleaning wax such as a liquid crystal or a rosin-containing wax adhered 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.

[0019]

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, diluted with ion-exchanged water so that the organic matter content became 10%, and the aqueous detergent solution was heated at a temperature of 20 to 100 ° C. It was left still for 30 minutes. Detergent composition No. In all of Nos. 1 to 6, it was confirmed that 30% or more of the contained organic matter was separated from the aqueous phase. Then, using a cleaning composition shown in Table 1, a printed board (10 cm × 15 cm) [test material 1] treated with a rosin-based flux, and a naphthenic mineral oil (40 ° C., 350 cSt) were applied (1 g / g).
m ² ) steel test piece (10 cm × 15 cm) [test material 2] and a glass substrate (10 cm) coated with liquid crystal (5 g / m ² )
× 10 cm) [Test material 3] was washed. The washing was performed by ultrasonic washing at 40 ° C. for 3 minutes. 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. Then, the rinse drainage after use is taken in two tall beakers, one is left at 60 ° C. for 10 minutes or 30 minutes (comparative method), and the other is a steel plate 50 cm ^{2 on} one side.
The pieces were immersed face to face at an interval of 1 cm, and allowed to stand at 60 ° C. for 10 minutes while applying an AC current of 200 V (the method of the present invention). At this time, the detergent composition No. In 1 to 6, the organic matter separated into an upper layer and a lower layer. The water layer is sampled and its COD (chemical oxygen demand) is measured (A
Value), COD (B value) of the rinsing liquid before the treatment, and the organic matter separation ratio [(B value−A value) ÷ (B value)] × 100
Was calculated. Table 1 shows the results.

[0021]

[Table 1]

As is clear from the results in Table 1, the detergent composition No. In 1 to 6, the organic matter separation rate is high,
It was found that the method of the present invention in which the separation treatment was performed while applying a voltage exhibited an excellent separation ratio in a shorter time than the comparative method in which no voltage was applied. Further, it was confirmed that the rinse liquid obtained by separation had a low COD, and thus contained little organic matter. In addition, those having a separation rate of 30% or more (detergent composition N
o. Nos. 1 to 6) showed good rinsing properties even when the aqueous layer was reused as a rinsing liquid, and those having a separation rate of 70% or more were excellent.

[0023]

According to the present invention, it is possible to efficiently separate and remove high-concentration organic substances from the rinse wastewater, and to simplify the subsequent wastewater treatment process. Electronic components or precision components to which stains such as grease, wax, liquid crystal, and flux have adhered can be industrially advantageously cleaned. Furthermore, since the rinse drainage separated according to the present invention can be used again as a rinse liquid, the amount of water used for the rinse can be greatly reduced, and the cost is excellent.

Continued on the front page (51) Int.Cl. ⁶ Identification code FI C11D 3/18 C11D 3/20 3/20 C23G 1/24 C23G 1/24 5/02 5/02 C02F 1/46 (58) Fields surveyed (Int.Cl. ⁶ , DB name) B08B 3/00-3/14 C02F 1/46 B01D 17/06 C23G 5/00-5/24

Claims (3)

(57) [Claims] 1. A cleaning method in which electronic parts or precision parts are washed with a cleaning agent and then rinsed with water, wherein a nonionic surfactant and / or a hydrocarbon compound, a poorly water-soluble compound is used as an active ingredient of the cleaning agent. Containing a compound selected from alkyl esters and alkyl ketones, and
When the detergent is diluted with water or the water is evaporated to make the content of organic matter 10% by weight, and the aqueous solution of the detergent is allowed to stand at a temperature of 20 to 100 ° C. for 30 minutes, the weight of the organic matter contained becomes 30% by weight. % Or more of a cleaning composition having a property of separating from an aqueous phase, using water of 5 to 100 ° C. as a rinsing liquid, and applying a voltage while keeping the rinse drainage after rinsing at 20 ° C. or more. A method for cleaning electronic parts or precision parts, wherein organic matter is separated from the rinse drainage. 2. The cleaning method according to claim 1, wherein the remaining liquid obtained by separating and removing the organic matter from the rinse waste liquid after the rinse is circulated and used as a rinse liquid. 3. The cleaning method according to claim 1, wherein the electronic parts or precision parts to which the wax containing flux, liquid crystal or rosin is adhered are washed.