JPH05295394A - Solvent composition for cleaning - Google Patents

Abstract

PURPOSE: To obtain a solvent composition for cleaning which can be used in a low-temperature cleaning process and is usually used at an elevated temperature below its boiling point.

CONSTITUTION: This composition is produced by using a mixture, desirably an azeotropic or substantially azeotropic mixture of dichloropentafluoropropane with 1,1-dichloroethane. An article is cleaned by contact with the composition or its vapor.

COPYRIGHT: (C)1993,JPO

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention uses solvents and / or solvent vapors to clean contaminated articles such as metal articles, textile articles, glass articles, plastics, electronic components and printed circuit boards. , Solvent cleaning methods and more particularly solvent cleaning methods and their use in solvent cleaning methods.

[0002]

BACKGROUND OF THE INVENTION Solvent cleaning methods of immersing or cleaning contaminated articles in halogenated hydrocarbon solvents and / or vapors thereof are well known and commonly Is used for. Solvent cleaning methods involving several steps of dipping, rinsing and drying are common, and it is often not possible to use the solvent at ambient temperature or at elevated temperatures below the boiling point of the solvent with ultrasonic agitation. It is well known. Examples of solvents used in these cleaning methods are 1,1,2-trichloro-1,2,2-trifluoroethane, 1,1,1-trichloroethane, trichloroethylene, perchloroethylene and methylene chloride. These solvents may be used alone or in admixture with co-solvents such as aliphatic alcohols or other low molecular weight polar additives, and to some extent light, heat and metal depending on the article to be cleaned. It is often stabilized against the degradation induced by the presence of the class.

In known solvent cleaning processes, and in particular those in which the solvent is used at elevated temperatures, solvent vapors tend to disappear from the cleaning system into the atmosphere. Another amount of solvent loss occurs when the solvent is loaded into and removed from the cleaning plant and when the solvent used is recovered by distillation. Although care is usually taken to minimize the loss of solvent into the atmosphere, for example by improving plant design and vapor recovery systems, the cost of preventing all loss is prohibitive and often prohibitive. According to the practical cleaning method of (1), the solvent vapor is slightly lost into the atmosphere.

Until recently, the use of common cleaning solvents has been satisfactorily carried out in that they are stable, relatively low-toxic, nonflammable substances which are considered to have good environmental impact. Was thought to be. However, recent evidence suggests that alternative solvents are desirable because at least some of the common solvents have long-term adverse effects on the stratosphere, the ozone layer.

[0005]

According to the present invention, a cleaning solvent composition containing a mixture of at least one isomer of dichloropentafluoropropane and 1,1-dichloroethane. Will be provided.

The dichloropentafluoropropane used can be a mixture of isomers, but "225ca"
Is known in the art as 1,1-dichloro-2,2,
It is preferred to contain at least a majority of 3,3,3-pentafluoropropane.

1,3-Dichloro-1,2,2,3,3-pentafluoropropane, which is technically known as "225cb", is another useful isomer.

1,1-dichloro-2,2,3,3,3-
Pentafluoropropane and 1,1-dichloroethane form an azeotrope or essentially an azeotrope mixture, which is a preferred cleaning composition of the present invention, and in particular It is the preferred composition for cleaning methods with boiling solvents. About 80.5% by weight of azeotrope
1,1-dichloro-2,2,3,3,3-pentafluoropropane and about 19.5% by weight of 1,1-dichloroethane and has a boiling point of about 51.4 ° C.

Although azeotropes may be preferred as they maintain an essentially constant composition during use, some non-azeotrope mixtures have been found by the present inventor, eg about 18 wt / wt. Wt% 1,1-dichloro-2,2,3,
Mixtures containing 3,3-pentafluoropropane may be attractive in that they exhibit practically satisfactory compositional stability in use and give the possibility to control the cleaning power of the cleaning composition.

The amounts of dichloropentafluoropropane and 1,1-dichloroethane in the non-azeotropic mixture can be varied within wide limits, but to render it nonflammable so that it has no flash point. It should contain sufficient dichloropentafluoropropane.

The mixture should contain at least 15% by weight of dichloropentafluoropropane. A useful mixture contains 15-90% by weight dichloropentafluoropropane. It is often preferred that the mixture contains 20-80% by weight of dichloropentafluoropropane. However, the inventors have found that below 20% w / w dichloropentafluoropropane is an effective diluent for 1,1-dichloroethane, a solvent commonly used today, namely 1,1,1. 2-trichloro-1,2,2-trifluoroethane and 1,
There are two preferred mixtures that replace the 1,1-trichloroethane. One such mixture contains about 50:50 wt% dichloropentafluoropropane and 1,1-dichloroethane, another mixture about 18:80 wt% dichloropentafluoropropane and 1,1-dichloroethane. It contains dichloroethane.

Dichloropentafluoropropane and 1,
In addition to 1-dichloroethane, the cleaning composition may contain aliphatic hydrocarbons and / or polar compounds such as aliphatic alcohols, preferably alcohols containing 2 to 6 carbon atoms. Methanol, ethanol and propanol (n-propanol or isopropanol) are preferable, and ethanol is particularly preferable. The amount of alcohol may be up to 50% by weight of the cleaning composition, but about 10
Amounts up to wt% are preferred. A typical ternary mixture is about 2
% To about 7% alcohol by weight.

1,1-dichloro-2,2,3,3,3-
Pentafluoropropane, 1,1-dichloroethane and at least some of the lower alkanols form an azeotrope, and such ternary azeotrope represents another preferred aspect of the invention, especially boiling. A preferred aspect of the cleaning method with a solvent is shown. About 4 azeotropes containing methanol
It boils at 6.4 ° C. and consists of about 76.3% by weight dichloropentafluoropropane, about 17.7% by weight 1,1-dichloroethane and about 6% by weight methanol. An azeotrope containing ethanol boiled at about 51 ° C and contained about 79% by weight.
Of dichloropentafluoropropane, about 18% by weight of 1,1-dichloroethane and about 3% by weight of ethanol. On the other hand, a ternary azeotrope containing propanol does not appear to be produced.

As mentioned above, the cleaning composition can contain aliphatic hydrocarbons, acyclic or cyclic saturated or ethylenically unsaturated hydrocarbons, which are examples of suitable components. Suitable hydrocarbons that are liquid at room temperature include 30 ° C to 7 ° C.
There are hydrocarbons with boiling points in the range of 5 ° C, preferably 40 ° C to 65 ° C. 1,1-dichloro-2,2,3,3,
A particularly suitable hydrocarbon for use with 3-pentafluoropropane and 1,1-dichloroethane is cyclopentane, which has a boiling point of 50 ° C., but the compound does not appear to form a ternary azeotrope.

Examples of hydrocarbons suitable for inclusion in the cleaning solvent composition of the present invention include, among others, the following components: Boiling point (° C) 2-methylbutane (isopentane) 30 2-methylbut-1 -Ene (amylene) 31 pentane 35-36 2-methylbut-2-ene 35-38 cyclopentane 50 2,2-dimethylbutane (neohexane) 50 4-methylpent-1-ene 53-54 3-methylpent-1- En 54 cis-4-Methylpent-2-ene 57-58 2,3-Dimethylbutane 58 2-Methylpentane (isohexane) 61 2-Methylpent-1-ene 62 3-Methylpentane 63 2-Methylpent-2-ene 67 n-Hexane 69 3-methylpent-2-ene 69 methylcyclopentane 72 Cleaning solvent composition The amount of hydrocarbon can vary within a wide range, for example, it can vary from 20 to 80 wt%. However, hydrocarbons are generally flammable, so the amount of hydrocarbons is preferably such that the cleaning composition remains nonflammable. In particular, 1,1 which is also flammable with hydrocarbons
-The combined amount with dichloroethane is preferably below the amount at which the cleaning composition is flammable and exhibits a flash point. In addition to the requirement that the liquid composition be non-flammable, the vapors generated during use of the composition are also preferably non-flammable.

The cleaning compositions of the present invention may contain one or more stabilizers such as those often used in known cleaning compositions, especially nitroalkanes and epoxides.

Since the cleaning composition of the present invention can be used as a substitute for the solvent used in any of the known cleaning methods, the article to be cleaned according to the present invention can be cleaned with the cleaning composition and / or its composition. A method of cleaning an article is provided that comprises contacting with steam. The cleaning composition can be used in low temperature cleaning methods, but is usually used at elevated temperatures below its boiling point.

[0018]

The present invention is illustrated by the following examples, but the invention is not limited thereto.

Example 1 This example illustrates the use of the azeotrope of the present invention to remove flux from printed circuit boards.

1,1-dichloro-2,2,3,3,3-
The flux residue of the ionic solder was removed from the printed circuit board by the following method using pentafluoropropane and 1,1, -dichloroethane (80.5% halopropane / 19.5% haloethane). A test piece (5 cm x 7 cm) cut from a FR4 circuit board coated with copper was coated with a known weight of solder cream, and then Micro VPS
Reflowed in the apparatus. Solder cream is multi-core (M
ulticore) 62% tin / 38 available as PRAB3
It was a% lead solder.

The solvent was boiled in a beaker equipped with an upper cooling coil that circulated cold water to produce a boiling liquid phase and a vapor phase. The contaminated test plate was dipped in a boiling solvent liquid for 60 seconds and then kept in the vapor phase for 30 seconds.

The degree of contamination of the residual ionic flux of the test plate, expressed as sodium chloride (mg) per cm ^2, was measured using a Protonique Contaminometer. The degree of ion flux contamination of the unwashed test plate was measured, and the removal rate (%) of ion contamination was calculated by the washing method. 72.4% of ionic contaminants were removed.

Examples 2-3 These examples illustrate the use of the ternary azeotropes of this invention to remove ionic solder flux from printed circuit boards.

The test procedure described in Example 1 was repeated using the ternary azeotropes listed in Table 1 below. The results obtained are shown in Table 1.
Shown in.

[0025]

[Table 1]

Example 4 This example illustrates the compatibility of the cleaning solvent composition of the present invention with plastic materials.

Samples of the three plastic materials (AC) were completely dried by heating them in an oven at 80 ° C. for 1 hour and then leaving them in a desiccator for a minimum of 24 hours. Remove the plastic sample from the desiccator, weigh it immediately and place in boiling solvent for 30 minutes (± 5
Second), then allowed to cool in air for 5 minutes and then weighed. The plastic sample was then placed in a dessicator for 24 hours and reweighed. The results are shown in Table 2 below.

The plastic materials tested were as follows: A-polypropylene copolymer [LYM123] B-nylon [malanyl A125] C-epoxy / glass fiber laminate [FR4] The solvents used in the test were: 80: 20% by weight mixture of I-1,1-dichloro-2,2,3,3,3-pentafluoropropane (DCPFP) and 1,1-dichloroethane (DCE).

II-DCPFP and DCE 60: 40% by weight mixture.

III-DCPFP and DCE 20:80
Wt% mixture.

A 79: 18: 3 wt% mixture of IV-DCPFP, DCE and ethanol.

In the comparative test, V-1,1,2-trichloro-1,2,2-trifluoroethane was used as a solvent.

[0033]

[Table 2]

Examples 5-6 These examples illustrate the stability of the cleaning solvent compositions of the present invention against decomposition in the presence of aluminum, zinc and mild steel.

Nitromethane (0.3% by weight) was added to the azeotrope listed in Table 3 and the resulting solvent (50 ml).
Was charged to a reflux device heated on an oil bath.

Weighed test pieces of aluminum, zinc and mild steel were placed in a reflux apparatus and partly immersed in the boiling solvent. Approximately 3 days later the metal coupon and solvent were removed for analysis. Wash metal pieces with a small amount of deionized water (hold this and use it later to extract ionic species from the used solvent), rinse with another volume of water and brush to avoid any deposits Rubbed The metal pieces were then rinsed with acetone, dried and reweighed.

The used solvent is metal rinse water (see above)
The extract was analyzed for chloride ion and fluorine ion.

According to the results obtained, no change in weight was detected in any of the metal test pieces, and no change in halogen ion content in the solvent was detected. There was also no change in the GC (gas chromatography) traces for the solvent.

The mild steel specimens were clean and shiny with no visible signs of the tide corresponding to the liquid / vapor interface.
The aluminum and zinc test pieces were also clean and bright, but very slight tide marks were seen for each test piece.

[0040]

[Table 3]

Continuation of front page (51) Int.Cl. ⁵ Identification number Office reference number FI Technical indication location H05K 3/26 7511-4E (72) Inventor David Ziogi Macbeth United Kingdom. Chessier Dubriyu 7.4 Kyuev. Runcorn. The Heath (No other address displayed)

Claims (13)

[Claims] 1. A cleaning solvent composition comprising a mixture of at least one isomer of dichloropentafluoropropane and 1,1-dichloroethane. 2. The solvent composition according to claim 1, wherein most of dichloropentafluoropropane is 1,1-dichloro-2,2,3,3,3-pentafluoropropane. 3. A solvent composition according to claim 2 which contains up to about 20% w / w 1,1-dichloroethane. 4. The solvent composition according to claim 1, which contains 15 to 90% by weight of dichloropentafluoropropane. 5. 1,1-Dichloro-2,2,3,3,3
The solvent composition according to claim 2, wherein -pentafluoropropane and 1,1-dichloroethane are in the form of an azeotrope or a substantially azeotrope. 6. The solvent composition according to claim 1, further comprising an aliphatic hydrocarbon, a polar organic compound, or both of them. 7. The solvent composition according to claim 6, wherein the polar organic compound is an alcohol containing 2 to 6 carbon atoms. 8. A solvent composition according to claim 7, which contains not more than about 10% w / w of alcohol. 9. 1,1-Dichloro-2,2,3,3,3
The solvent composition according to claim 7, wherein -pentafluoropropane, 1,1-dichloroethane and alcohol form an azeotrope. 10. The solvent composition according to claim 9, wherein the alcohol is methanol or ethanol. 11. 1,1-Dichloro-2,2,3,3,
The solvent composition according to claim 6, which comprises 3-pentafluoropropane, 1,1-dichloroethane, and cyclopentane. 12. A method for cleaning an article, which comprises contacting the articles to be cleaned with the solvent composition according to claim 1, its vapor, or both. 13. The method according to claim 12, wherein the cleaning is carried out at an elevated temperature.