JPH07122038B2 - Solution for Hydrolyzing Silicone as Paint Additive, Cleaning Solution for Silicone-Containing Paint, and Cleaning Method - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention was started with the task of cleaning a silicone-containing paint adhering to a paint drum, and it is a solution for hydrolyzing silicone as a paint additive, a silicone-containing paint cleaning solution and a cleaning solution. It is about the method.

[0002]

2. Description of the Related Art Conventionally, in the case of removing paint adhered to a paint drum can, in the case of an iron drum can, a method of knocking out iron powder or the like with shotplast after incineration, or rarely a method of washing with alkali after incineration is known. There is.

However, there is a limit to how many times this method can be repeated, and when the drum can is reused for paints, 100% of the paint is used because residual iron powder is mixed in the paint and settles at the bottom. There was a drawback that I couldn't. Therefore, stainless steel drums, which do not have the above-mentioned drawbacks and have a long life and can be repeatedly used, have come to be used. However, it is necessary to find an effective paint cleaning liquid because the drum can is expensive and needs to be reused and cannot be incinerated to remove the adhered paint.

By the way, in high-quality paints for automobiles, etc., silicone is mixed as a leveling agent as a paint additive and a defoaming agent. If this silicone remains on the wall of the drum can, it repels the paint, so removal of the silicone is essential for cleaning the can.

As a cleaning liquid for silicone oil (for example, Shin-Etsu Silicone KF96, Toshiba Silicone TSF-451), an alkaline aqueous solution or an alcoholic alkaline aqueous solution is known, but a stainless steel drum can to which silicone-containing paint is adhered is usually washed. Since the treatment is carried out at a high temperature, the use of an aqueous alkaline solution which is a conventionally known silicone oil cleaning solution generates an alkaline gas having a strong irritating odor, which is not practical in an actual cleaning line.

[0006]

SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a cleaning solution and a cleaning method for a silicone-containing paint, which is new and can be practically used in a normal cleaning line.

Another object of the present invention is to provide a novel solution for hydrolyzing silicone as a paint additive.

[0008]

In order to solve the above problems, the inventors of the present invention have conducted extensive studies and found that a liquid consisting of caustic alkali, a glycol ether derivative, a polyoxymonocarboxylic acid salt and water not only has a cleaning effect on paint. The present inventors have completed the present invention by finding that they have the function of hydrolyzing silicone as a paint additive to form a monomer.

That is, the present invention is a glycol ether derivative,
It comprises a solution for hydrolyzing silicone as a paint additive, characterized by comprising caustic alkali, polyoxymonocarboxylic acid salt and water.

The present invention also comprises a cleaning solution for a silicone-containing paint, characterized by comprising caustic alkali, a glycol ether derivative, a polyoxymonocarboxylic acid salt and water.

The present invention also uses the cleaning solution at about 80 ° C.
It comprises a method for cleaning a paint containing silicone, which comprises heating for 5 minutes or more.

The silicone used in the present invention is a silicone oil as a coating additive such as a leveling agent and an antifoaming agent. For example, dimethyl such as Shin-Etsu Silicone KF-96, Toshiba Silicone TSF-451 and Shin-Etsu Silicone KP-322. Polysiloxane type, methylphenyl polysiloxane type, and modified organosilicon compounds of these types, most of the organic groups of which are methyl groups and some of which include phenyl groups and the like.

Examples of the caustic alkali used in the present invention include caustic soda and caustic potash, and examples of the polyoxymonocarboxylic acid salt include glyceraldehyde and
Erythrose, threose, ribose, arabinose,
Examples thereof include salts of xylose, glucose, mannose, galactose and the like, which are obtained by oxidizing the aldehyde group of D-form aldose to a carboxyl group.

The glycol ether derivatives include 3-methoxy-3-methyl-1-butanol and 3-methyl-3.
-Methoxy-butyl acetate, ethylene glycol monomethyl or dimethyl ether, ethylene glycol monoethyl or diethyl ether and the like are used.

The composition of each component in the liquid (hereinafter represented by weight ratio and weight%) may be within the following range.

Table 1 Caustic alkali 5-20% (preferably 8-15%) Glycol ether derivative 2-10% (preferably 3-8%) Polyoxymonocarboxylic acid 1-7% (preferably 2-6%) Water 70-92% (preferably 75-90%)

When this liquid is used for hydrolysis of silicone as a paint additive and washing of paint mixed with silicone, good effects can be obtained if it is left at room temperature for a long time, but preferably 80 ° C. Under the heating conditions before and after, a remarkable hydrolysis effect and cleaning effect can be obtained by heating for a short time of 5 minutes or more.

[0017]

When the liquid of the present invention acts on an organosilicon compound (silicone), the compound is hydrolyzed and the Si-O bond is cleaved to form a monomer (dimethylsilanediol, diphenylsilanediol, etc.).

As a cleaning method, the cleaning liquid of the present invention is sprayed or sprayed and brushed on a container to which a paint containing a slight amount of silicone is attached, and the container is left at room temperature or heated. As a result, the liquid decomposes the silicone, and the paint mixed with silicone is completely washed away.

[0019]

Example 1 caustic soda: ethylene glycol dimethyl ether: sodium gluconate: water weight ratio of 13:
1 g of 1% silicone liquid (toluene solution) (Shin-Etsu Silicone KP-322) in 100 g of the solution of 4: 2: 81
Is added to make a 100 ppm solution, and while stirring well, 8
After heating to 0 ° C., the decomposition rate of the organosilicon compound (silicone) due to the change in heating time was determined by the solvent extraction-IR method.

The heating was carried out in a water bath, and the heating time was 5 minutes, 15 minutes and 30 minutes. Then, the mixture is allowed to cool to room temperature, adjusted to be weakly acidic (pH 3 to 4) with 30% hydrochloric acid, and then n
-Extracted with hexane (100 ml). (Extraction time 15
Min) The n-hexane layer was dehydrated and filtered with anhydrous sodium sulfate, the solvent was distilled off (rotary evaporator), dried under reduced pressure, and the volume was adjusted to 10 ml of n-hexane for IR measurement.

The results are shown in FIGS. In FIG. 1, ↓ represents the characteristic absorption band of the organosilicon compound, and the characteristic absorption band of the organosilicon compound is 1261 cm ⁻¹ (Si—C).
The peak intensity ratio of each characteristic absorption band with respect to H ₃ symmetry and bending vibration is 1099/1261 = 0.88,1022 / 1.
Since 261 = 1.09 and 803/1261 = 0.90, the recovery rate of the organosilicon compound was 97% without heating.

2 to 4, the characteristic absorption band 1261 cm ⁻¹ (Si—CH ₃ symmetry, bending vibration) of the organosilicon compound was not confirmed under any of the heating conditions of 5, 10 and 30 minutes. .

From the above results, it is considered that most of the organosilicon compounds added to the silicone hydrolyzate of the present invention are hydrolyzed by the heating operation at 80 ° C. (5 minutes or more).

[0024]

Example 2 caustic soda: ethylene glycol monoethyl ether: sodium galactoate: water weight ratio of 1
0: 4: 4: 82 solution, caustic soda: 3-methyl 3-methoxy-butylacetate: sodium xylonate: water weight ratio 15: 6: 4:
And a caustic soda: 3-methyl 3-methoxy-1-butanol: sodium gluconate: water weight ratio of 12: 5: 3: 8.
When the same treatment operation as in Example 1 was performed on the solution of 0, it was revealed that the organosilicon compound was completely hydrolyzed.

[0025]

Example 3 The weight and infrared absorption of the extract (hydrolyzate) obtained with and without dehydration operation on anhydrous n-hexane layer obtained in the same manner as in Example 1 The (IR) spectrum was examined.

When the dehydration operation was carried out, 4.4 mg of extract was obtained, and when the dehydration operation was not carried out, 14.7 mg of extract was obtained. The extract thus obtained was insoluble in n-hexane, and toluene, chloroform and Soluble in acetone.

The infrared absorption spectra of the extract that was dehydrated and the extract that was not dehydrated are as shown in FIGS. 5 and 6, and comparing the former with the latter shows that the former has a fingerprint area (15).
The absorption band of (00 cm ⁻¹ or less) is sharp and it is considered that there are few impurities. As a result of the search, it coincided with diphenylsilanediol shown in FIG. 7.

The results of the analysis of the extract by the ¹ H-NMR method are as shown in FIG. 8. Si-CH ₃ , Si-C
A signal derived from ₆ H ₅ was detected. The results obtained by the FD / MS method are as shown in FIG. 9, and m (mass) / z (charge) = molecular weight = 216 was strongly detected.

In FIG. 9, the horizontal axis represents m / z molecular weight, and the vertical axis represents m / z = 2 of diphenylsilanediol.
The ratio of other molecules when 16 is set to 100 is expressed in%.

From these, it is estimated that the main component of the hydrolyzate is diphenylsilanediol.

From the above results, the organosilicon compound (silicone) is hydrolyzed in the liquid of the present invention to give S
It is considered that the i-O bond is cleaved to produce a monomer (dimethylsilanediol, diphenylsilanediol, etc.).

Here, dimethylsilanediol {(C
_{H 3) 2 Si (OH)} 2} is highly hydrophilic hydroxyl, believed to be held in the aqueous layer by solvent extraction.

The obtained hydrolyzate was insoluble in n-hexane, but since the starting material, 1% silicone liquid, was a toluene solution, it was considered that the one dissolved in the toluene layer was extracted and detected. To be

[0034]

Example 4 1 g of 1% silicone liquid (100 ppm) was added to the same cleaning liquid as in Example 1 and left for 1 day at room temperature. The IR spectrum is shown in FIG. Was not recognized. From this, it was confirmed that the silicone was hydrolyzed.

In the coating plate test, the extraction liquid was dropped on a cold-rolled tin-plated steel plate, dried and then coated with a paint, and the presence or absence of the repellency after baking was confirmed.

[0036]

According to the present invention, even an organosilicon compound having a low concentration of 100 ppm can be completely hydrolyzed at a relatively low temperature in a short time.

As a result, when the cleaning liquid of the present invention is used, even a small amount of silicone mixed in the coating material is hydrolyzed into a monomer, which has the epoch-making effect that the coating material can be completely and easily washed and removed.

[Brief description of drawings]

FIG. 1 is an IR spectrum of an experiment for measuring the recovery rate of an organosilicon compound without heating.

FIG. 2 IR spectrum with heating time of 5 minutes

FIG. 3 IR spectrum with heating time of 15 minutes

FIG. 4 IR spectrum with heating time of 30 minutes

FIG. 5: IR spectrum of hydrolyzate of organosilicon compound (with dehydration operation)

FIG. 6 IR spectrum of hydrolyzate of organosilicon compound (without dehydration operation)

FIG. 7: IR spectrum of diphenylsilanediol standard product

FIG. 8 ¹ H-NMR spectrum of an organosilicon compound

FIG. 9: FD / M of organosilicon compound (with dehydration operation)
S spectrum

FIG. 10: IR spectrum after leaving the silicone-added virgin cleaning solution at room temperature for 1 day

Claims (3)

[Claims] 1. A solution for hydrolyzing silicone as a paint additive, which comprises a caustic alkali, a glycol ether derivative, a polyoxymonocarboxylic acid salt, and water. 2. A cleaning liquid for silicone-containing paint, which comprises a caustic alkali, a glycol ether derivative, a polyoxymonocarboxylic acid salt and water. 3. A method for cleaning a silicone-containing paint, which comprises heating at about 80 ° C. for 5 minutes or more using a cleaning liquid composed of caustic alkali, a glycol ether derivative, a polyoxymonocarboxylic acid salt, and water.