JPS5910758B2 - azeotropic solvent composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to novel azeotropic solvent compositions, particularly azeotropic solvent compositions comprising atlag-rollodifluoroethane, a C4 alcohol, and nitroethane.

Chlorofluoroethane solvent is non-toxic, has low toxicity, and can be used to clean oils and fats without attacking materials to be cleaned made of polymeric substances such as rubber and plastics. It has various advantages such as excellent selective dissolving performance for dissolving grease and the like. Recently, chemical methods have been used to clean and remove high-melting point rosin flux, other high-melting point greases, and oils from printed circuit boards, such as in the electronics industry.

It is desired that a stable and safe fluorocarbon solvent with a relatively high boiling point be developed. Among chlorofluorocarbon solvents, trichlorotrifluoroethane has excellent chemical stability and workability, but its dissolution performance is not fully satisfactory.
Furthermore, since it has a low boiling point (47.6° C.), it is essentially impossible to satisfy the above requirements.

On the other hand, tetrachlorodifluoroethane has better solubility than trichlorotrifluoroethane and has a higher boiling point (
92.8°C), which makes it possible to dissolve the high melting point contaminants, but its use is limited because it lacks sufficient chemical stability and has a high melting point (26,0°C). That is the reality.

Conventionally, tetrachlorodifluoroethane (hereinafter referred to as Freon 1)
For the purpose of lowering the melting point of 12), many methods have been proposed in which other organic solvents are combined. However, many such methods are generally impractical because they impair the useful properties and chemical stability of Proso 112, or because many such mixed solvents do not form azeotropic compositions. By the way, an azeotropic solvent composition consisting of Prosol 112, an alcohol, and nitromethane has been known as an extremely advantageous method for improving the chemical stability of Prosol 112 and lowering its melting point (Japanese Patent Publication No. 1983-1999).
1232).

However, since this azeotropic composition uses a large excess of nitromethane than is necessary to stabilize Proso 112, there is a risk of attacking the materials to be cleaned, such as rubber and plastics, and furthermore, there is a risk of toxicity and price. They cannot avoid being disadvantaged in this respect as well. The present inventors took advantage of the characteristics of tetrachlorodifluoroethane as a solvent to solve its disadvantages such as chemical instability and high melting point, and created a new solvent that is safe for the materials mentioned above and has various other advantages. The present invention was completed by discovering a boiling solvent composition. That is, the present invention provides an azeotropic solvent composition comprising 89.0 to 64.6% by weight of tetrachlorodifluoroethane, 3.7 to 34.2% by weight of alcohol having 4 carbon atoms, and 7.3 to 1.2% by weight of nitroethane. This is related to.

Here, tetrachlorodifluoroethane 1,12,2-
In addition to tetrachloro-1,2-difluoroethane alone, its isomer 1,1,12-tetrachloro-2
, 2-difluoroethane.

In addition, alcohol with 4 carbon atoms is n-butylalconoK
, isO-butyl alcohol, Sec-butyl alcohol and tert-butyl alcohol.

The composition and physical properties of the azeotropic solvent composition of the present invention are shown in Table 1 below.

For reference, the above-mentioned known examples are also listed in the same manner. According to the composition of the present invention, since a chemically stable, low-toxicity, and relatively high-boiling solvent is provided, it is possible to easily clean high-melting point flux from printed circuit boards, other high-melting point greases, and oils. Can be removed.

In addition, since the amount of nitroethane used is small, it has less negative impact on the materials mentioned above, and is advantageous in terms of toxicity and cost.In addition, since the alcohol has 4 carbon atoms and is an excellent solvent, it has a relatively low negative impact on the items being cleaned. It has excellent selective dissolution performance, which improves dissolution performance even with a small amount. In addition, since the composition of the present invention forms an azeotropic composition, liquid management during use and solvent recovery and reuse are extremely easy. The azeotropic composition of the present invention can be prepared by adding and mixing each component in any order in the composition ratios shown in Table 1, or by distilling a mixture of each component in any ratio. can be manufactured.

The azeotropic solvent composition of the present invention is effective over a wide range of purposes, such as cleaning the flux of printed circuit boards, cleaning eyeglass frames after polishing, and cleaning workpieces cut using water-soluble cutting oil. used for. Next, the azeotropic solvent composition of the present invention will be explained with reference to Examples and Experimental Examples. Example 1 Solvent mixture 5009 having the composition shown in Table 2 below was placed in a distillation flask and distilled under normal pressure using a rectification column having 30 theoretical plates.

As a result, the lowest azeotropic point was shown at 88.7°C.

Also, in Table 2, instead of n-butyl alcohol, I
sO-butyl alcohol. When Sec-butyl alcohol and tert-butyl alcohol are used,
The lowest azeotropic points were 108.3°C, 98.8°C, and 82.9°C, respectively. As a result of analyzing each of these fractions by gas chromatography, they had the compositions shown in Table 2. Experimental Example 1 The following experiment was conducted to examine whether each of the azeotropic solvent compositions obtained in Example 1 was suitable for cleaning high melting point fluxes.

Printed circuit board made of phenolic resin copper-clad laminate (60
A pre-flux shown in the following table was applied to the entire surface of the 50 m area, and then a post-flux was applied, followed by firing at about 250°C for 2 minutes.

After this substrate was cooled to room temperature, it was immersed in 300 ml of each of the above-mentioned solvent compositions placed in a beaker.

The degree of flux removal was visually observed and the results are shown in the table below.

Experimental Example 2 The following experiment was conducted to find out that the azeotropic solvent composition obtained in Example 1 has an excellent effect on removing abrasives without soaking the material to be cleaned, which is made of plastic. .

A white rod (a mixture of alumina, silica sand, etc. mixed with oil and fat) was applied as an abrasive to the cloth surface of a commonly used hub polisher to polish an eyeglass frame made of cellulose acetate.

Claims (1)

[Claims] 1 Tetrachlorodifluoroethane 89.0-64.6
Weight%, carbon number 4 alcohol 3.7-34.2% by weight
and an azeotropic solvent composition consisting of 7.3 to 1.2% by weight of nitroethane.