JPH1036894A - Cleaning method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a cleaning method with a new hydrofluorocarbon solvent which method provides a similar effect on cleaning dirt such as oil or flux adhering to a metal part, etc., to that of a chlorofluorocarbon such as CFC-113, is excellent in noncombustibility and low-toxicity, and does not deplete the ozone layer. SOLUTION: Dirt on an article to be cleaned is removed by using a warm bath of a mixture comprising a hydrofluorocarbon(HFC) or a hydrofluoroether(HFE) having a b. p. of 30-150 deg.C or a liq. mixture of these compds. and an org. compd. such as a glycol ether or an ester having a b.p. at least 50 deg.C higher than that of the HFC or HFE and compatible with the HFC or HFE. Then org. compds. adhering to the article are removed by rinsing it with the HFC or HFE alone.

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. And more particularly to a cleaning method using a highly fluorinated hydrofluorocarbon or hydrofluoroether liquid.

[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 used in many cases. 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.
Since the dissolving power (hereinafter referred to as cleaning power) of the dirt component is inferior, first, an object to be cleaned is converted into a hydrocarbon (hereinafter referred to as HC) -based liquid having excellent cleaning power, such as a petroleum-based cleaning liquid.
After cleaning with a terpene-based cleaning liquid or an alcohol-based cleaning liquid, the cleaning liquid adhering to the object to be cleaned is FC liquid or HF.
After rinsing with C liquid, or after washing with a mixture of FC liquid or HFC liquid and HC liquid,
A method of rinsing with FC liquid or HFC liquid has been proposed.

[0004]

However, petroleum-based cleaning liquids, terpene-based cleaning liquids, higher alcohol-based cleaning liquids and the like used for cleaning have excellent cleaning power,
Since they are hardly soluble in FC liquids or HFC liquids, these cleaning liquids are not removed while adhering to the surface of the object to be cleaned. Also, lower alcohols that are compatible with the HFC liquid have a drawback of low boiling point and flammability.

[0005]

Means for Solving the Problems The present inventors have found that by using an organic compound which is compatible with HFC and has a high boiling point as an organic compound to be mixed with an HFC liquid,
It has been found that there is no danger of rinsing of the cleaning liquid adhering to the object to be cleaned or danger of ignition, and it is possible to clean the surface of the object to be cleaned.

That is, according to the present invention, an article to be cleaned has a boiling point of 30.
Hydrofluorocarbon (HF) in the range of
C) or a mixture of a hydrofluoroether (HFE) or a mixture thereof and an organic compound having a boiling point higher than that of the HFC or HFE liquid by 50 ° C. or more and compatible with the HFC or HFE. A method for cleaning articles, comprising removing stains using a warm bath, and then rinsing and removing organic compounds attached to the parts to be cleaned using the HFC or HFE alone.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION Here, hydrofluorocarbon (HFC) is a fluorinated hydrocarbon 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.

[0008] The HFC or HFE liquid used in the present invention has a boiling point of 30 to 150 ° C. (Hereinafter, both HFC and HFE are collectively referred to as “HFC / E”.) If the boiling point of the HFC / E liquid is less than 30 ° C., evaporation loss is large, and there is also a problem of water condensation. Further, when the boiling point of the HFC liquid exceeds 150 ° C., the evaporation rate becomes slow,
The HFC / E remaining on the surface of the article to be cleaned becomes droplets in a state where the dirt is concentrated, and after evaporation, forms a portion where the dirt is concentrated on the surface of the article to be cleaned.

Among such HFC / Es, HFC is specifically 1,1,1,2,3,4,4,5,5,5.
5-decafluoropentane (hereinafter referred to as HFC43-10m
ee. Boiling point 55 ° C), 1,1,2,2,3,3
4,4-octafluorobutane (hereinafter referred to as 338 pcc; boiling point: 44 ° C.);
2,2,2-tetrafluoroethyl-heptafluoropropyl ether (boiling point 40 ° C.), 1,1,1,2,3
3-hexafluoro-2-heptafluoropropoxy-3- (1,2,2,2-tetrafluoroethoxy)-
And propane (boiling point: 104 ° C.).

[0010] The organic compound used by mixing with the HFC / E liquid (hereinafter simply referred to as "organic compound") has a boiling point at least 50 ° C, preferably 100 ° C, higher than the boiling point of the HFC liquid.
Higher than ℃ and compatible with HFC / E liquid.

When washing with an organic compound incompatible with the HFC / E liquid, it is difficult to rinse off the organic compound attached to the surface of the article to be washed with HFC / E.
The boiling point of the organic compound is 50 ° C. higher than the boiling point of the HFC / E liquid
Above, preferably not higher than 100 ° C, HFC / E
Since the temperature is not higher than the boiling point of the liquid, the cleaning effect by heating cannot be expected, and the effect of reducing the flammability cannot be expected.

As such an organic compound, the boiling point is HF.
A glycol ether or ester compound having a boiling point of C / E higher than that of C / E by 50 ° C. or more is suitable, and a mixture of both can also be used. Specifically, examples of the glycol ether include triethylene glycol dimethyl ether and the like, and examples of the ester compound include dimethyl succinic acid, dimethyl glutaric acid, dimethyl adipic acid, and mixtures thereof.

The mixing ratio of the HFC / E liquid and the organic compound having compatibility with the HFC / E liquid depends on the type of both components, the boiling point difference between them, and the degree of contamination of the article to be cleaned.
Liquid / organic compound (weight ratio) = 10 / 90-70 / 30
It is preferred to mix in the range of. If the amount of the organic compound is small relative to the HFC / E liquid, the detergency decreases, and if the amount is too large, the flammability increases and the HFC / E in the next step undesirably results in poor rinsing of the organic compound.

The cleaning method of the present invention is suitably used for cleaning dirt such as flux. In the present invention, first, the articles to be cleaned are cleaned with a mixture of HFC / E and an organic compound, and then the organic compounds attached to the articles to be cleaned are rinsed with the HFC / E alone.

In order to wash articles by such a method, a tank filled with a mixture of HFC / E and an organic compound (washing tank) and a tank filled with HFC / E (rinse tank) as shown in FIG. Are housed in one container, the upper portions of which are common spaces, and a washing apparatus in which the vapor layer of the washing tank and the rinsing tank are shared is suitable.

Hereinafter, the method of the present invention will be specifically described with reference to the accompanying drawings. In FIG. 1, a plurality of tanks, 2, 3 and 4 are installed at the bottom of a washing device 1 and
It is partitioned by 0, 11, etc. Further, the cleaning device 1 has an open top, and has a cooling unit 6 on a side surface on the top. The cooling unit 6 is provided near the top for the purpose of preventing loss of HFC / E vapor, and on the side so as not to hinder the taking in and out of the object to be cleaned.

The washing tank 2 is a warm bath containing a mixed solvent of HFC / E and an organic compound having compatibility with the HFC / E. The washing tank 2 is heated by a heater 7 and is equipped with a stirrer 8 to enhance the washing effect. good. The article to be cleaned is introduced into the apparatus through the upper opening of the cleaning apparatus 1, is immersed in a cleaning tank 2 containing a mixture of HFC / E and an organic compound mixed at a desired ratio, and adheres to the surface of the article to be cleaned. Removed stains.

It is preferable that the temperature of the cleaning tank 2 is high in order to enhance the cleaning effect. On the other hand, when the temperature at which the mixture boils is used, the liquid composition changes due to evaporation of the mixture. There's a problem. Therefore, the temperature of the washing tank is usually between the boiling point of HFC / E and the boiling point of the mixture.
In addition, a temperature at which the article to be cleaned is not damaged by heat is employed.

The article to be washed after washing has a mixture of HFC / E and an organic compound adhered to its surface. If the organic compound remains on the surface of the article to be cleaned, dirt dissolved in the organic compound may cause stains on the surface of the article to be cleaned, and drying takes a long time due to a low evaporation rate. Therefore, the organic compound in the mixture is replaced with HFC / E by rinsing the article to be cleaned with HFC / E alone in a rinsing tank.

In FIG. 1, reference numeral 3 denotes a first rinsing tank, and reference numeral 4 denotes a second rinsing tank, all of which are tanks for containing a liquid substantially consisting of the HFC / E solvent alone. The first rinsing bath 3 is provided with a heater 9 so that the HFC / E solvent can be kept in a boiling state, while the second rinsing bath is kept at a temperature equal to or lower than the boiling point of the HFC / E solvent, and the rinsing effect is reduced. A stirrer or an ultrasonic oscillator 12 may be provided to increase the height.
Each tank is partitioned by a partition plate, but the upper part is a common space, and the HFC / E saturated steam area 5 is provided between the cooling unit 6 and the lower tank group (2-4).

By heating the first rinsing tank 3, H
Although FC / E is brought into a boiling state and vaporized, the density of HFC / E vapor is higher than that of air (for example, the density of air at room temperature is about 1.3 kg / l, whereas the density of HFC / E vapor is about 1.3 kg / l.
The saturated vapor density at the boiling point of -10 mee is about 10.0 g /
l. ), The HFC / E vapor stagnates in the vessel, and if it is going to rise further, the vapor is condensed and liquefied by the cooling unit 6 arranged in the upper part of the vessel, so that the tank group 2,
A saturated vapor region 5 of the HFC / E solvent is formed between the cooling units 6 and 3 and 4.

The rinsing method by HFC / E may be any method. For example, in FIG.
First rinsing tank 3 in which the FC / E alone is boiling
(Boiling HFC / E bath) or the second rinsing tank 4 (cold HFC / E bath) provided with a stirrer or ultrasonic oscillator.
Bath) or one or both rinsing tanks,
The mixed liquid on the surface of the article to be cleaned may be rinsed off.

In order to carry out precise rinsing, the article to be washed after washing is immersed in boiling HFC / E of the first rinsing tank 3, and the organic compound in the mixed solution adhering to the surface of the article to be washed is washed with HFC / E. E, and further rinsed in the second rinse tank 4 (cold HFC
/ E bath), and the remaining organic compounds are replaced with HFC / E. Then, the article to be cleaned cooled to a temperature lower than the boiling point of HFC / E is pulled up, and the saturated vapor region 5 of HFC / E is removed.
HFC / E is condensed and liquefied on the surface of the article to be cleaned to further replace the organic compound with HFC / E to complete the rinsing.

The article to be cleaned after the rinsing is applied to the cleaning apparatus 1.
Taken out from the upper opening. The surface of the article to be cleaned
Dirt and high boiling organic compounds have already been removed, and HFC / E
Since it is in a state of being wet only by a single substance, by vaporizing and evaporating it, a clean and stain-free article can be obtained.

Hereinafter, the present invention will be described in detail with reference to examples. [Example 1] Carnauba wax was heated and melted on a square stainless steel plate having a side of 100 mm and uniformly applied to obtain a sample to be cleaned. HFC4 as HFC liquid
Using a mixture of dimethyl succinate, dimethyl glutarate, and dimethyl adipate (DBE; manufactured by Du Pont; boiling point: 205 ° C.) as an organic compound, using HFC43-10mee (boiling point: 55 ° C.) and 35 wt. %, Dimethyl succinate, dimethyl glutarate,
A mixture of dimethyl adipate was mixed at a ratio of 65% by weight to obtain a washing liquid mixture.

This mixture is accommodated in the cleaning tank 2 of the apparatus shown in FIG. 1 (but without the ultrasonic oscillator 12), and the first rinsing tank 3 and the second rinsing tank 4 are filled with HFC43-10me.
e. The temperature of the washing tank was set to 80 ° C., the first rinsing tank was boiled, while the second rinsing tank was HFC43-
10 mee was kept below boiling. In this state, the sample to be cleaned was first immersed in a cleaning tank, and the sample was successively immersed in each cleaning liquid and brought into contact with steam in accordance with the following cleaning cycle for cleaning. (1) Washing tank: washing solution mixture warm bath (80 ° C.): 2 minutes immersion (2) First rinsing tank: boiling HFC bath: 30 seconds immersion (3) Second rinsing tank: cold HFC bath: 30 seconds immersion (4) HFC saturated steam area: steam washing 30 seconds After washing was completed, a sample was taken out, and the washing property was visually judged by the following two steps. Good: wax was completely removed. Impossible: wax adhered to one surface. The results are shown in Table 1.

Example 2 Flux (PO-F-350, manufactured by Sumitomo Metal Co., Ltd.) was applied to a 65 mm square printed circuit board.
0M) 60 μl were soldered. The printed circuit board was allowed to stand at room temperature for 1 hour to obtain a sample to be cleaned. HFC
HFC43-13mee (boiling point 55 ° C.) was used as the liquid, and triethylene glycol dimethyl ether (boiling point 218 ° C.) was used as the organic compound.
35% by weight of mee and 65% by weight of triethylene glycol dimethyl ether were mixed to prepare a cleaning liquid mixture.

Using this mixture, a washing test was conducted in the same manner as in Example 1. However, ultrasonic cleaning was performed in the second rinse tank using an apparatus in which the ultrasonic oscillator 12 was installed in the second rinse tank, and the cleaning cycle was as follows. (1) Cleaning tank: cleaning solution mixture hot bath (80 ° C.): immersion 30 seconds (2) First rinsing tank: boiling HFC bath: immersion 30 seconds (3) Second rinsing tank: cold HFC bath: ultrasonic cleaning 30 seconds ( 4) HFC saturated steam area: steam cleaning for 30 seconds The results are shown in Table 1.

Example 3 The same article sample to be washed as in Example 1 was used. 1,2,2,2- as HFE liquid
Tetrafluoroethyl-heptafluoropropyl ether (boiling point 40 ° C .; “Freon E-1” (Du Pont
A mixture comprising dimethyl succinate, dimethyl glutarate and dimethyl adipate (DBE; Du Pon) as organic compounds.
t company; boiling point: 205 ° C.) and 20% by weight of HFE,
A mixture composed of dimethyl succinate, dimethyl glutarate, and dimethyl adipate was mixed at a ratio of 80% by weight to obtain a washing liquid mixture. Using this mixture, a washing test was carried out in the same manner as in Example 1 using the apparatus shown in FIG. 1, and the washing property was visually judged. Table 1 shows the results.

Example 4 The same article to be cleaned as in Example 3 was used. 1,1,1,2,3,3- as HFE liquid
Hexafluoro-2-heptafluoropropoxy-3-
(1,2,2,2-tetrafluoroethoxy) -propane (boiling point 104 ° C .; “Freon E-2” (Du Pon
using HFE), propylene glycol monopropyl ether as an organic compound, HFE at a ratio of 40% by weight, and propylene glycol monopropyl ether at a ratio of 60% by weight. And Using this mixture, a washing test was carried out in the same manner as in Example 3 using the apparatus shown in FIG. 1, and the washing property was visually determined. Table 1 shows the results.

Comparative Example 1 In Example 1, instead of a mixture of dimethyl succinate, dimethyl glutarate and dimethyl adipate as a high boiling organic compound, a mixture consisting of normal dodecane and normal undecane (NS Clean 200; Nippon Mining ore) Except for using the first boiling point of 189 ° C.) and using the apparatus of FIG.
A cleaning test with a mixed solvent with HFC43-13mee was performed, and the organic solvent used was HFC43-10mee.
Temperature is not compatible with NS Clean 2
Even in the boiling state, the temperature rose only up to 50 ° C., and wax was adhered to one side, so that the wax could not be removed. Table 1 shows the results.

[0032]

[Table 1] HFC: HFC43-10mee HFE: 1,2,2,2-tetrafluoroethyl-heptafluoropropyl ether HFE: 1,1,1,2,3,3-hexafluoro-2-heptafluoropropoxy-3- (1 , 2,2,2-Tetrafluoroethoxy) -propane

[0033]

According to the cleaning method of the present invention, hydrofluorocarbon (HF) which is nonflammable but has poor cleaning power
By performing cleaning and rinsing using C) or hydrofluoroether (HFE) and a specific organic compound, a cleaning effect equivalent to that of CFC-113 can be obtained with respect to dirt such as oil flux without danger of flammability. It became possible to obtain.

[Brief description of the drawings]

FIG. 1 is an example of an apparatus for performing a cleaning method of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Container 2 Cleaning tank 3 1st rinsing tank (boiling HFC / E bath) 4 2nd rinsing tank (cold HFC / E bath) 5 HFC / E saturated vapor area 6 Cooling unit 7 Heater 8 Stirrer 9 Heater 10 Partition wall 11 Partition Wall 12 ultrasonic oscillator

Claims (4)

[Claims] 1. An article to be cleaned is prepared by mixing a hydrofluorocarbon (HFC) or a hydrofluoroether (HFE) having a boiling point in the range of 30 to 150 ° C. or a mixture thereof with a liquid having a boiling point of 50 to 50 ° C. higher than the boiling point of the HFC or HFE liquid.
The dirt is removed using a warm bath of a mixture of an organic compound having a boiling point higher than or equal to 0 ° C. and compatible with the HFC or HFE, and then the organic compound adhering to the part to be cleaned with the HFC or HFE alone is removed. A method for cleaning articles characterized by rinsing and removing. 2. The method according to claim 1, wherein the hydrofluorocarbon is 1,1,
3. The cleaning method according to claim 2, which 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 method according to claim 1, wherein the organic compound is a glycol ether, an ester, or a mixture thereof.
The cleaning method according to any one of Items 1 to 3.