JPH10192797A - Washing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make it possible to obtain an excellent washing effect with incombustibility and low toxicity like chlorofluorocarbon to stains of oils, fluxes, etc., to metallic parts, etc., even if an org. solvent hardly soluble in hydrofluorocarbon or hydrofluoroether (HFC/E) is used. SOLUTION: This washing device is constituted so as to have a washing tank 2, a shower washing device 3 and a rinsing tank 4. In such a case, the HFC/E liquid having a b.p. of 30 to 150 deg.C and an org. compd., for example, hydrocarbon liquid, which is hardly soluble in the liquid and has the b.p. higher by >=50 deg.C than the b.p. of this HFC/E are separated to two layers and are packed into the washing device. The wash is washed by the upper layer liquid contg. mainly the org. compd. liquid and is then shower washed by the lower layer liquid mainly contg. the HFC/E liquid. The liquid of the upper layer sticking to the surface of the wash is washed away and the wash surface is rinsed with the HFC/E liquid. Further, the wash is steam washed by the satd. steam of the HFC/E liquid.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cleaning method for efficiently removing oil stains and the like, particularly flux, adhered to metal parts, plastic parts, glass parts, and the like in the precision machine industry, optical machine industry, electronic industry, and the like. The present invention further relates to a cleaning method using a highly fluorinated hydrofluorocarbon liquid and a cleaning solution of an organic compound hardly soluble therein.

[0002]

2. Description of the Related Art Conventionally, in a method for cleaning metal parts and the like, 1,1,2-trichloro-1,2,2,
A mixture of 2-trifluoroethane (hereinafter referred to as CFC-113) to which alcohols or water and a surfactant are added has been frequently used. However, in recent years, the use of chlorofluorocarbons (hereinafter, referred to as CFCs) such as CFC-113 has been regulated due to the ozone problem.

As a substitute for CFC-113, a perfluorocarbon (hereinafter referred to as FC) liquid in which all hydrogen atoms of hydrocarbons are replaced by fluorine atoms, or a part of hydrogen atoms of hydrocarbons is only fluorine atoms A substituted hydrofluorocarbon (hereinafter, referred to as HFC) liquid containing no chlorine atom can be used as a cleaning liquid.
C or HFC cleaning liquid is CFC-113 or other CFC
Like liquid, it has low toxicity, non-flammability, low corrosiveness and does not contain chlorine, so there is no danger of destroying the ozone layer.
First, the object to be cleaned is washed with a hydrocarbon-based liquid having an excellent detergency, such as a petroleum-based cleaning liquid, a terpene-based cleaning liquid, or an alcohol-based cleaning liquid, because the dissolving power of the dirt component (hereinafter referred to as cleaning power) is poor. A method of rinsing a cleaning liquid attached to an object to be cleaned with an FC liquid or an HFC liquid,
Alternatively, there has been proposed a method of performing cleaning with a mixture of an FC liquid or an HFC liquid and an HC-based liquid, followed by rinsing with an FC liquid or an HFC liquid.

[0004]

However, petroleum-based cleaning liquids, terpene-based cleaning liquids, higher alcohol-based cleaning liquids, and the like used for cleaning have excellent detergency, but have a high cleaning power.
Since it is hardly soluble in C liquid or HFC liquid, simply cleaning with a cleaning liquid and rinsing with FC liquid or HFC liquid are not sufficient for rinsing. Therefore, the cleaning liquid is not removed while adhering to the surface of the object to be cleaned. Could not be reached.

As one method for solving the above problem, the inventors of the present invention first set an article to be cleaned to a boiling point of 30 to 1.
Using a warm bath of a mixture of an HFC liquid in the range of 50 ° C. and an organic compound having a boiling point higher than that of the HFC liquid by 50 ° C. or more and compatible with the HFC, such as glycol ethers and esters. Remove dirt and then remove the HF
A method of rinsing and removing an organic compound attached to a part to be cleaned with C alone to clean the article was proposed (Japanese Patent Application No. 9-3).
852).

[0006] This method is an excellent method that can remove stains on articles to be cleaned by performing cleaning and rinsing with a relatively simple apparatus. However, this method is a specific method having a high boiling point compatible with HFC. The use of organic compounds limits the choice of cleaning agents, and depending on the type of soil to be removed, a solvent that is inferior in compatibility with HFCs such as hydrocarbons but has excellent cleaning power must be used. May not be
It is desired to develop a cleaning method that can use a cleaning agent that is hardly soluble in such an HFC liquid.

When a sparingly soluble cleaning agent is used in the HFC liquid, the HFC liquid and the cleaning agent are separated into two layers. However, the present inventors utilize this phenomenon to improve the rinsing step in the conventional method. In addition, the present inventors have found a method of efficiently removing stains on articles to be cleaned even when using a cleaning agent that is hardly soluble in HFC liquid by performing cleaning with a cleaning agent in the upper layer and shower cleaning with a lower layer liquid.

[0008]

That is, the present invention uses a cleaning device having a cleaning tank, a rinsing bath, a shower cleaning device, and a steam supply unit, and has a boiling point of 30 to 150 ° C. or a hydrofluorocarbon (HFC) or a hydrofluoroether. (HFE) or a mixture thereof and a liquid, which is hardly soluble in the liquid and has a boiling point of 50 ° C. higher than the boiling point of the liquid.
The washing tank is filled with a high organic compound liquid, and the upper layer mainly containing the organic compound liquid is mainly filled with HFC or HF.
After separating into two layers with the lower layer containing the E liquid, the object to be cleaned is immersed in the upper layer of the cleaning tank and washed with the organic compound liquid,
It is taken out into the upper space of the cleaning tank, and it is shower-washed with a lower layer liquid to wash off the upper layer liquid adhering to the surface of the object to be cleaned, and then the object to be cleaned is washed in a rinsing tank filled with HFC or HFE liquid. This is a cleaning method characterized by rinsing, and then performing steam cleaning with saturated steam of HFC or HFE liquid.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION Here, hydrofluorocarbon (HFC) is a fluorinated carbon compound in which part of the hydrogen atoms of a hydrocarbon is replaced only by fluorine atoms and does not contain chlorine atoms. , HFE) are fluorinated ethers in which some of the hydrogen atoms of the ethers are replaced only by fluorine atoms and do not contain chlorine atoms.

[0010] The boiling point of the HFC or HFE liquid used in the present invention is 30 to 150 ° C. (HFC, H
Both FEs are collectively called "HFC / E". ) HFC
If the boiling point of the / E liquid is less than 30 ° C., the evaporation loss is large,
There is also the problem of water condensation. Further, when the boiling point of the HFC / E liquid exceeds 150 ° C., there is a problem in that the evaporation rate becomes slow, and it takes a long time to dry the object to be cleaned.

The HFC / E liquid may be a chain compound or a cyclic compound, and may be an HFC or HFE liquid alone or a mixture thereof. The HFC / E liquid may be used by adding a nitroalkane, benzotriazole, or the like as a stabilizer.

Among such HFC / Es, specifically, 1,1,1,2,3,4,4,5,5 as HFC liquids
5,5-decafluoropentane (hereinafter referred to as HFC43-1
It is called 0mee. Boiling point 55 ° C), 1,1,2,2,3
3,4,4-octafluorobutane (hereinafter HFC33
8pcc. (Boiling point: 44 ° C.).

The HFE liquid includes 1, 2, 2, and 2
-Tetrafluoroethyl-heptafluoropropyl ether (boiling point 40 ° C), 1,1,1,2,3,3-hexafluoro-2-heptafluoropropoxy-3-
(1,2,2,2-tetrafluoroethoxy) -propane (boiling point 104 ° C.), methylnonafluorobutyl ether, ethylnonafluorobutyl ether, hexafluoroisopropyl-1,1,2,3,3,3-hexafluoropropyl Ether and the like can be exemplified.

The organic compound liquid used in the present invention is HF
Hardly soluble in C / E liquid and its boiling point is HFC / E
The temperature is 50 ° C. or higher, preferably 100 ° C. or higher than the boiling point of the liquid. Specifically, the boiling point of the organic compound liquid is desirably 80 ° C or higher, and particularly desirably 150 ° C or higher. If the boiling point of the organic compound liquid is close to the boiling point of the HFC / E liquid, it is easy to vaporize and the flammability increases, which is not preferable.

An organic compound liquid that is hardly soluble in HFC / E liquid is defined as HFC / E liquid having an amount of HFC / E
/ E means 10% by weight or less based on the weight of the liquid. Therefore, H containing an organic compound liquid in excess of the saturation solubility
The liquid mixture of the FC / E liquid and the organic compound liquid is separated into two layers: an upper layer mainly containing the organic compound liquid and a lower layer mainly containing the HFC / E liquid.

Examples of such organic compound liquids include aliphatic hydrocarbon compounds, carbocyclic hydrocarbon compounds and higher alcohols. More specifically, paraffin liquids having 8 or more carbon atoms, highly soluble petroleum Examples include naphtha, kerosene, terpins, pine oil and the like.

In the above-mentioned mixed liquid of the HFC / E liquid and the organic compound liquid, the HFC / E liquid having a lower boiling point is vaporized preferentially during boiling, so that the temperature does not become higher than the boiling point of the HFC / E liquid. The organic compound liquid hardly vaporizes, so that the flammability can be reduced.

The mixing ratio between the HFC / E liquid and the organic compound liquid depends on the type of the two components, the boiling point difference between the two components, the degree of contamination of the object to be cleaned, and the like. It is preferable to mix in the range of (weight ratio) = 50/50 to 95/5. If the amount of the organic compound liquid is small relative to the HFC / E liquid, the detergency decreases, and if the amount is too large, the two-layer separation in the cleaning tank does not occur. The organic compound solvent is HF
The feature of the present invention of washing with a lower layer liquid containing a C / E liquid cannot be utilized.

In the present invention, the HFC / E liquid and the organic compound liquid are used, and the immersion cleaning, shower cleaning, rinsing and steam cleaning are combined. Hereinafter, the cleaning method of the present invention will be specifically described with reference to FIG.

In FIG. 1, a cleaning apparatus 1 includes a cleaning tank 2,
A shower cleaning device 3, a rinsing tank 4, and an HFC / E boiling tank (steam supply unit) 5 are provided. First, an object to be cleaned is introduced into the cleaning device 1 through the upper opening thereof, and the HFC / E
It is immersed in the cleaning tank 2 containing both the liquid and the organic compound liquid.

The cleaning tank 2 is heated by a heater 21, and the above two components are mainly composed of an upper layer 2 containing an organic compound liquid.
3 and a lower layer 24 mainly containing the HFC / E liquid, and the HFC / E liquid is in a boiling state.

The object to be cleaned is immersed in the upper layer 23 for cleaning, thereby removing stains on the surface of the object to be cleaned. Since the surface of the object to be cleaned thus washed is mainly wetted by the upper layer liquid containing the organic compound liquid, the object to be cleaned is taken out from the cleaning tank 2 and then, in the upper space 22 thereof, mainly by the shower cleaning device 3. Shower washing is performed with a lower layer liquid containing the HFC / E liquid. That is, the lower layer liquid is taken out from the pump 31 and jetted from the nozzle 32 to replace the upper layer liquid on the surface of the object to be cleaned with the lower layer liquid.

The temperature in the cleaning tank 2 has reached the boiling point of the HFC / E liquid by heating by the heater 21.
/ E liquid evaporates. Cleaning tank 2 by this evaporation
In order to prevent a change in the liquid composition in the washing tank, a cooler 25 is provided on the upper inner wall of the washing tank, and the vapor is condensed and vaporized and returned to the washing tank 2 or the HFC / E liquid is washed from the HFC / E boiling tank 5 by the washing tank. HFC / E in the cleaning tank
Means are to prevent a decrease in the liquid, meanwhile, store an upper layer liquid mainly composed of an organic compound liquid overflowing from the washing tank 2 in the storage tank 2A and reflux the liquid in the washing tank to prevent a decrease in the organic compound liquid. Taken.

The object to be cleaned after the shower cleaning is immersed in the rinsing tank 4 containing the HFC / E liquid. Although the shower liquid is wet on the surface of the object to be cleaned by the lower layer liquid containing the organic compound liquid, the organic compound liquid in the lower layer liquid can be easily HFC /
Diluted with E liquid and replaced with HFC / E liquid. An ultrasonic oscillator 41 or a stirrer (not shown) may be attached to the rinsing tank 4 in order to enhance the replacement effect in the rinsing tank. The temperature of the rinsing bath is maintained at a temperature lower than the boiling point of the HFC / E liquid, and the object to be cleaned is cooled here.

The object to be cleaned after the rinsing is introduced into a saturated vapor region 7 of the HFC / E liquid formed in the upper part of each tank below the cooler 6 and is condensed and vaporized on the surface of the object to be cleaned.
The final rinsing is performed by the E vapor, and is taken out from the upper opening of the cleaning device 1.

The surface of the object to be cleaned after rinsing is HFC
/ E, which is easily vaporized and evaporated, yielding a dry object to be cleaned free of stains or stains.

The HFC / E condensed and liquefied in the cooler 6
The liquid is returned to the rinsing tank 4 so that the rinsing tank is always filled with clean HFC / E liquid, and the organic compound liquid brought into the rinsing tank from the cleaning tank 2 with the object to be cleaned is removed. It is introduced into the HFC / E boiling tank 5 by overflow.

Further, H overflowed from the boiling tank 5
The FC / E liquid is returned to the cleaning tank 2. HFC in boiling tank
/ E is heated by the heater 51 and vaporized HFC /
The E vapor is cooled by the cooler 6 to form a saturated vapor region 7, while the condensed HFC / E liquid is returned to the rinsing tank 4 via the weir 61.

As described above, in the present invention, the HFC / E liquid, which is the lower layer component of the cleaning tank, is circulated between the lower layer and the HFC / E liquid, and the HFC / E liquid and the organic compound liquid are condensed, refluxed, and overflowed. Each of them is returned to the processing tank to eliminate the loss of the cleaning liquid and to maintain the liquid balance of the whole system.

The saturated vapor region 7 is a region where the final rinsing step is performed, and it is desirable that the vapor contains as little organic compound liquid as possible. FIG. 2 shows an example of a cleaning apparatus improved for such a purpose. A condenser 8 is provided so that HFC / E vapor containing a small amount of HC vapor generated from the cleaning tank 2 does not enter a saturated vapor region. H generated from boiling tank 4
Means are provided for leading to the condenser 8 with the FC / E vapor. (In the figure, the thick arrows in the vapor layer indicate HC vapor, and the thin arrows indicate HFC / E vapor.) Other structures are shown in FIG.
Is the same as

[0031]

The present invention will be described below in more detail with reference to examples. [Example 1] HFC43-10mee as HFC liquid
(Boiling point 55 ° C.) and a mixture (NS) of normal dodecane and normal undecane as an organic compound liquid
Clean 200; manufactured by Nippon Mining & Chemical Co .; initial boiling point: 189 ° C), 3 kg of HFC43-10mee, and 2 kg of a mixture consisting of normal dodecane and normal undecane are shown in FIG.
And the two layers were separated, and the rinsing tank and the steam supply unit were filled with HFC43-10mee.

The washing tank and the steam supply part where the two layers were separated were heated, and after the HFC43-10mee in the washing tank was brought to a boiling state, it was further left at the boiling state for 3 hours. The liquid composition of the upper and lower layers of the boiling tank was as shown in Table 1 as a result of analysis by gas chromatography.

[0033]

[Table 1]

Ball ring (diameter 10 mm, length 10 m)
m) was immersed in gear oil (Gelco Multi 5; manufactured by Showa Shell), the amount of gear oil adhered to the ball ring was measured, and this was used as an object to be cleaned. The ball ring was immersed in the following cleaning cycle. Washing was performed by shower washing and steam contact. (1) Wash tank upper layer liquid immersion 1 minute (2) Wash tank lower layer liquid Shower wash 10 seconds (3) Rinse tank immersion 1 minute (4) HFC saturated vapor area Steam wash 1 minute After washing is completed, take out ball ring and wash The amount of oil adhering to the object to be cleaned later was measured to determine the cleaning rate. Table 2 shows the results.

Example 2 The same cleaning as in Example 2 was performed using a cap nut (outer diameter 4.5 mm, length 9 mm, inner diameter 3 mm) instead of a ball ring as an object to be cleaned. Table 2 shows the results.

[Comparative Example 1] Washing was performed in the same manner as in Example 1 except that the object to be washed was washed by immersion and steam contact according to the following washing cycle without performing shower washing with a washing tank lower layer liquid. The rate was measured. Table 2 shows the results. (1) Soaking tank upper layer liquid immersion 1 minute (2) Rinse tank immersion 1 minute (3) HFC saturated steam area Steam cleaning 1 minute

Comparative Example 2 The same cap nut (outer diameter 4.5 mm, length 9) as used in Example 2 was used instead of the ball ring.
mm, inner diameter 3 mm), and the same cleaning as in Comparative Example 1 was performed. After the washing was completed, the cap nut was taken out and the washing rate was measured. Table 2 shows the results.

[0038]

[Table 2] Cleaning result ：: Cleaning rate 99% or more ：: Cleaning rate 95% or more and less than -99% Δ: Cleaning rate 90% or more and less than -95% ×: Cleaning rate less than 90%

[0039]

According to the cleaning method of the present invention, by combining a specific cleaning and a rinsing step, even when a cleaning agent which is hardly soluble in a hydrofluorocarbon or hydrofluoroether liquid is used, it is possible to remove dirt such as oil flux. CFC-11 using a non-flammable but less detergency hydrofluorocarbon or hydrofluoroether that can efficiently remove dirt and stains on the cleaning articles.
It is possible to obtain a cleaning effect equivalent to 3, and it is industrially advantageous because various organic solvents having excellent detergency can be widely used.

[Brief description of the drawings]

FIG. 1 is a diagram showing a basic configuration of a cleaning apparatus of the present invention.

FIG. 2 is a view showing another embodiment of the cleaning apparatus of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Cleaning device 2 Cleaning tank 2A storage tank 21 Heater 22 Upper space of cleaning tank 2 23 Upper layer liquid 24 Lower layer liquid 25 Cooler 3 Shower cleaning device 31 Pump 32 Nozzle 4 Rinse tank 41 Ultrasonic transmitter 5 HFC / E boiling tank 51 Heater 6 Cooler 61 Weir 7 Saturated steam area 8 Condenser 81 Cooler

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁶ Identification code FI H01L 21/304 341 H01L 21/304 341V 351 351V

Claims (4)

[Claims] 1. A cleaning device having a cleaning tank, a rinsing bath, a shower cleaning device and a steam supply unit, having a boiling point of 30 to 1
Hydrofluorocarbon (HFC) or hydrofluoroether (HFE) or a mixture thereof at 50 ° C., and an organic compound liquid that is hardly soluble in the liquid and has a boiling point higher than the boiling point of the liquid by 50 ° C. or more in the cleaning tank. After filling, the upper layer mainly containing the organic compound liquid and the lower layer mainly containing the HFC or HFE liquid are separated into two layers, and the object to be cleaned is immersed in the upper layer of the cleaning tank and washed with the organic compound liquid. It is taken out to the upper space, and it is shower-washed with the lower layer liquid to wash off the upper layer liquid adhering to the surface of the object to be cleaned.
A cleaning method characterized by rinsing an object to be cleaned in a rinsing tank filled with an FE liquid, and further performing steam cleaning with HFC or saturated vapor of the HFE liquid. 2. The method according to claim 1, wherein the hydrofluorocarbon is 1,1,
The cleaning method according to claim 1, wherein the cleaning method is 1,2,3,4,4,5,5,5-decafluoropentane and / or 1,1,2,2,3,3,4,4-octafluorobutane. . 3. The method of claim 1, wherein the hydrofluoroether is 1,2,2.
2,2-tetrafluoroethyl-heptafluoropropyl ether and / or 1,1,1,2,3,3-hexafluoro-2-heptafluoropropoxy-3-
The cleaning method according to claim 1, wherein (1,2,2,2-tetrafluoroethoxy) -propane is used. 4. The organic compound liquid according to claim 1, wherein the liquid is at least one selected from aliphatic hydrocarbon compounds, carbocyclic hydrocarbon compounds and higher alcohols, or a mixture of two or more thereof. The washing method according to 1.