JPS589086B2 - Stabilized methyl chloroform composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to stabilized methyl chloroform compositions, and particularly to compositions that are stable at elevated temperatures in the presence of metals.

Methyl chloroform has a high ability to dissolve various oils and greases, is flame retardant, and has less toxicity and environmental pollution than other chlorinated hydrocarbons such as trichlorethylene and perchlorethylene, so it is suitable for degreasing and cleaning various metal items. It is widely used industrially as an agent.

However, methylchloroform is more easily decomposed than perchlorethylene or trichlorethylene and is inferior in stability.

Furthermore, perchlorethylene and trichlorethylene are unsaturated chlorinated hydrocarbons, whereas methylchloroform is a saturated chlorinated hydrocarbon, so its decomposition mechanism is different from that of perchlorethylene and trichlorethylene.

In particular, the decomposition of methyl chloroform is significantly accelerated in the presence of metals, especially aluminum.

Moreover, once this decomposition reaction starts, it proceeds as a chain reaction while generating hydrogen chloride, and finally produces a tar-like substance and a black substance.

In order to suppress this decomposition and prevent metal corrosion, stabilization of methyl chloroform is an essential requirement, and various stabilizers have been proposed so far.

For example, cyclic ethers, alcohols, nitriles,
These include epoxides and nitroalkanes.

However, even methyl chloroform stabilized by these stabilizers does not necessarily give satisfactory results under conditions of repeated use at high temperatures for long periods of time.

That is, even if the product contains almost no acid content at the beginning of use, it gradually generates acid content that does not lose its stability while being used at high temperatures.

When this acid content accumulates, it corrodes the metal of the equipment and the object to be washed due to interaction with coexisting water and moisture.

Normally, this accumulation of acid content tends to cause problems when the pH of the extracted water is below 6 when the methyl chloroform composition is extracted with an equal volume of water.

Regarding this point, methods of adding phenol, cresol, diallylamine mi-N-methylpyrrole, etc. have been tried, but the addition of these in small amounts does not have a sufficient effect of suppressing acid generation, and When added to the water, the liquid may be markedly colored, it may precipitate as an insoluble matter, or it may form an evaporation residue that stains the items to be washed.

As a result of repeated research in an attempt to eliminate these conventional drawbacks, the present inventors discovered that the generation of acid content can be significantly suppressed even under extremely harsh conditions by using a specific combination of stabilizers, and thus arrived at the present invention. .

That is, the present invention provides at least two stabilizers selected from the group consisting of cyclic ethers, nitroalkanes, butylene oxides, and saturated or unsaturated aliphatic alcohols, and the group consisting of benzophenones, phenyl salicylates, and penzotriazoles. To provide a methylchloroform composition characterized by containing one or more ultraviolet absorbers selected from the following and phenolic acid.

A methyl chloroform composition stabilized with two or more selected from the group consisting of cyclic ether, nitroalkane, butylene oxide, and saturated or unsaturated aliphatic alcohols contains phenols that capture and stabilize radicals and ultraviolet absorbing ability. It is truly amazing that the combined addition of an "ultraviolet absorber" provides a high degree of stability that cannot be obtained by adding each component individually.

Because of their synergistic effect, it is of great practical significance that sufficiently high stability can be achieved with an extremely small amount of addition.

Phenols used in the present invention include phenol, cresol, xylenol, probylphenol, tert
~Butylated phenol, thymol, ineugenol,
3-methyl-4-inglobylphenol, methoxyphenol, 1,1-bis(4-hydroxyphenyl:cyclohexane, etc.) are preferable.

Moreover, the ultraviolet absorber used in the present invention is 26 Onm to 41 Onm
Penzophenones, phenyl salicylates, and penzotriazoles that efficiently absorb 0 nm ultraviolet rays or near ultraviolet rays, for example, inpropanol 100ml.
Transmittance of a solution containing 2.5 mg (light path length 10 m)
m) is 50% or less in the wavelength range of 260 to 410 nm.

Among these, particularly preferred benzophenones are 4-hydroxybenzophenone, 2,4-dihytobenzobenzophenone, and 2-hydroxy-4-alkoxybenzophenone, and phenyl salicylates are phenyl salicylate, 4 -alkyl phenyl salicylate, and among penzotriazoles, 2-(2'-hydroxy-5'-
Methyl-phenyl)penzotriazole, 2-(2'-
Hydroxy-3',5'-di-tert-butyl-phenyl)penzotriazole, 2-(2'-hydroxy-
3',5'-dialkyl fluorophenyl)-5-chloropenzotriazole.

The amount of these phenols and ultraviolet absorbers added is usually 0.0001 to 0.1% by weight based on the total composition.

When it is less than 0.0001% by weight, the effect is not clear, and when it is more than 0.1% by weight, it is unnecessary.

Although the combination of phenols and ultraviolet absorbers, which is the main component of the present invention, is effective against methylchloroform that does not contain other stabilizers, it is necessary to obtain a higher synergistic effect under harsh conditions. This combination is 1,4~dioxane,
From cyclic ethers such as dioxolane and trioxane, nitroalkanes such as ditromethane and nitroethane, saturated or unsaturated aliphatic alcohols such as iso-butanol, tert-butanol, tert-pentanol, methylbutanol, and 1,2-butylene oxide. The method is carried out on methyl chloroform containing two or more known stabilizers selected from the group consisting of:

The amount of these known stabilizers used is not particularly limited, but is usually 1
~6% by weight is used.

As a result, the Frietel-Crafts type condensation and decomposition reaction caused by aluminum and the like can be sufficiently inhibited, and the overall practical performance of methyl chloroform can be achieved.

The composition obtained by the present invention is constantly used at high temperatures such as in steam degreasing and cleaning applications, distillation regeneration is often repeated, and water adhering to the object to be washed or moisture in the air is dissolved in the methyl chloroform composition. Even when saturated or a separated water layer coexists with the methyl chloroform composition, it is stable for a long time and does not corrode metals such as iron or zinc. It is of extremely high value.

The effects of the present invention will be clarified below while specifically illustrating the present invention through Examples and Comparative Examples, but of course the present invention is not limited to these Examples.

In addition, the stability test is based on the following method. 200 cc of the stability test sample is placed in a 500 cc hard glass Erlenmeyer flask equipped with a reflux condenser and an oxygen inlet tube.

Add to this a well-polished, thoroughly washed, and dried mild steel piece (JIS
-G-3141SPCC-B, 2 x 6 x 20 mm) is immersed in the sample, and other mild steel pieces (JIS-G-3141
Connect one SPCC-B (2 x 13 x 60 mm) to an oxygen introduction tube and suspend it in the vapor layer above the sample liquid level.

Adjust the tip of the oxygen introduction tube so that it is within 6 mm from the bottom of the Erlenmeyer flask, and heat it with a 150W frosted light bulb while passing room temperature oxygen bubbles saturated with water at a rate of 10 to 12 per minute. Adjust the flow rate of cooling water so that the sample condenses at less than half the height of the reflux condenser.

After continuing the test for a predetermined time, the sample was cooled to room temperature, the mild steel piece was taken out, and the color tone (APHA) of the sample liquid and the appearance of the mild steel piece were inspected.

The pH and APHA of the sample solution were measured by the following method.

pH: Add 50cc of neutral distilled water to 5Qcc of sample to make approximately 3
Shake vigorously for a minute, let stand to separate the aqueous layer, and measure the pH of the aqueous layer with a glass electrode pH meter.

APHA: Defined based on the chromaticity of JIS-KO101.

Examples and Comparative Example 1 1,4-dioxane 2.5% by weight, nitromethane 0.4
A stability test was conducted for 72 hours on methyl chloroform containing 0.5% by weight of 1,2-butylene oxide and a stabilizer shown in Table 1 added thereto.

The results are shown in Table-1. Hereinafter, the abbreviations for stabilizers are defined as follows.

BHT: 2,6-di-tert-butyl-4-methynophenol BHA: 3-tert-butyl-4-hydroxyanisole HPC: 1,1'-bis(4-hydroxyphenol)
Cyclohexane OPB: 1-oxy-3-methyl-4-isopropylbenzene PSA: Phenyl salicylate BPS: 4-tert-butylphenyl salicylate B
P: 4-hydroxybenzophenone MBP: 2-hydroxy-4-methoxybenzophenone DBP: 2,4-dihydroxybenzophenone BT: 2
-(2'-hydroxy-57-methyl-phenyl)penzotriazole BBT: 2-(2'-hydroxy-3,5'-di-t)
ert-butylphenyl)penzotriazole CBT:
2-(2'-hydroxy-3'-tert-butyl-5
'-Methyl-phenyl)-5-chlorobenzotriazole Example and Comparative Example 2 Further Table 2 for the present methylchloroform containing 0.8% by weight of methylbutanol, 0.4% by weight of nitromethane, and 0.5% by weight of iso-butanol. A stability test was conducted for 148 hours with the addition of the stabilizer shown below.

The results are shown in Table-2. Example and Comparative Example 3 Dioxolane 1.5% by weight, nitroethane 0.5% by weight
, tert-petanol 1.5% by weight, tert-butanol 1.5% by weight, 1,2-butylene oxide 0.5%
Table 3 shows the results of a 72-hour stability test conducted on methyl chloroform containing methyl chloroform with the stabilizer shown in Table 3 added thereto for 72 hours.

Examples and Comparative Example 4 Trioxane 15% by weight, 1,2-butylene oxide 0
．． A stability test was conducted for 72 hours on methyl chloroform containing 5% by weight, to which the stabilizers shown in Table 4 were further added.

The results are shown in Table 4.

Claims (1)

[Claims] 1. At least two stabilizers selected from the group consisting of cyclic ethers, nitroalkanes, butylene oxides, and saturated or unsaturated aliphatic alcohols, and ultraviolet rays selected from the group consisting of benzophenones, phenyl salicylates, and penzotriazoles. A methylchloroform composition characterized by containing soil as an absorbent and phenols.