JPH0244867B2 - PEINTORIMUUBAA - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a paint remover, and an object of the present invention is to provide a paint remover that has excellent storage properties and is useful for removing baked-on paint films.

As is well known, paint removers containing methylene chloride as the main removal component and ethylamine as a release-promoting component have been used for a long time as paint removers that are flame retardant, water removable, and have strong paint film removal properties. Are known. This product was developed in the United States for use in removing coatings from military aircraft, but recently it has become popular in Japan as well, where repainting of automobile bodies has become common. It is used as a paint remover that is effective for removing baked-on paint films such as paints, etc., and commercial products are also becoming available.
Currently, the paint remover used in Japan contains methylene chloride as the main stripping component and ethylamine as the stripping promoting component, which contains 70 to 90% by weight of methylene chloride (hereinafter simply referred to as %) and 2 to 5% of ethylamine. is an essential component, and about 10% of co-solvents (e.g. alcohols, esters),
Evaporation inhibitor (e.g. paraffin wax) 2-5
%, thickener (e.g. methylcellulose) 2-3
%, 5-6% surfactant (e.g. sodium alkylaryl sulfonate) and 3-6% formulation, which is flame retardant and water removable and contains phenolic enamel, It is said to be effective for removing baked-on coatings such as melamine and epoxy.

The present invention provides a paint trim containing methylene chloride and ethylamine as essential components as described above.
The aim is to improve the bar.

Specific examples of known formulations of paint removers containing methylene chloride and ethylamine as essential ingredients are as follows.

Examples of known formulations: Methylene chloride 72% Monoethylamine 5% Methanol 6% Ethylene glycol monoethyl ether 4% Paraffin wax 3% Methyl cellulose 2% Sodium alkylallylsulfonate 5% Distilled water 3% Edited by Kazuyuki Mihara: Explanation of paint Quoted from Science (page 391): Riko Publishing Co., Ltd., published on January 10, 1970.'' The paint trim bar is used by applying or spraying it on the target coating surface, and leaving it for a specified period of time. , a method of wiping it off using a cloth or the like is adopted.

The paint remover of the above-mentioned known formulation is, for example, a phenol enamel baked coating (120°C, 30 minutes).
, the baked coating can be completely removed by applying it to the painted surface, leaving it for about 10 minutes, and then wiping it off with a cloth.
Even if it is, the baked coating can be completely removed by applying it to the coating surface, leaving it for about 30 minutes, and wiping it off with a cloth.

As mentioned above, paint removers containing methylene chloride and ethylamine as essential ingredients exhibit extremely excellent performance in removing baked-on paint films, but they have poor storage stability and are It has the disadvantage that its performance begins to deteriorate about two weeks after it was mixed and prepared, and its performance deteriorates extremely after about one month from the time it was prepared. For example, even if a melamine baked coating (140°C, 30 minutes) can be completely peeled off after being left for about 30 minutes immediately after preparation, if 14 days have passed after preparation, about 50
It has deteriorated to the point where it cannot be completely peeled off unless it is left for a few minutes, and after 30 days have passed after preparation, approximately
It has become something that cannot be completely removed unless you leave it for at least 60 minutes.

It goes without saying that the above-mentioned disadvantages of paint removers containing methylene chloride and ethylamine can be avoided by mixing and preparing the respective formulations for each application. However, it is inconvenient for the user to prepare the product each time it is applied, and it is almost impossible to request this from small-scale automobile repair companies and painting companies in Japan.

In view of the current situation as described above, the present inventor has created a paint trim bar with excellent storage properties, specifically, methylene chloride and ethyl amine that do not cause performance deterioration even after at least one month has passed after preparation. We have conducted repeated tests and research with the aim of developing a paint remover containing the following.

First, the present inventor thoroughly investigated the causes of performance deterioration over time of commercially available paint trim bars containing methylene chloride and ethylamine, including the above-mentioned known formulation example.

As a result, they learned that the cause was that the amount of ethylamine blended decreased as time passed after preparation.

That is, the present inventor investigated changes over time after preparation of each component of a commercially available paint remover containing methylene chloride and ethylamine, and found that the content of ethylamine in the components As time passes, it decreases by about 17.6% on the 10th day, about 32.4% on the 20th day, about 43.2% on the 30th day, and about 52.7% on the 40th day. They confirmed that it decreased almost linearly to less than half. The amount of ethylamine was measured by gas chromatography and methyl red indicator method (the same applies hereinafter).

It should be noted that almost no changes were observed in other ingredients.

Although the theoretical explanation of the above phenomenon is still not fully understood, it is possible that the presence of methylene chloride in the formulation causes ethylamine to gradually change to ethylamine hydrochloride and cease to exert its peel-promoting effect on baked coatings. I'm guessing that.

Next, the inventor conducted experiments on a number of substances in search of a peel-promoting component to replace ethylamine in the formulation. However, it has not been possible to find a substitute that exhibits a release promoting effect on baked-on coatings comparable to that of ethylamine.

Incidentally, the peel-promoting effect of ethylamine on the peeling of baked paint films such as phenol enamel, melamine, and epoxy is extremely remarkable. It becomes almost impossible to peel off the baked coating. In addition, if the paint film is not baked, it can be removed very easily even if the formulation does not contain ethylamine.For phenol enamel paint films (drying at room temperature), apply it to the paint surface and leave it for about 3 minutes. The coating film can be completely removed by wiping it with a cloth.

Based on the above-mentioned facts, the present inventor sought a means to prevent the amount of ethylamine in the formulation from decreasing, and when ammonia is added to the formulation, the amount of ethylamine in the formulation is suppressed from decreasing over time. ,
The present invention was completed based on the remarkable new finding that the peeling performance for baked-on paint films can be maintained.

That is, the present invention provides a paint trim bar with excellent storage stability, which is characterized by containing methylene chloride, ethylamine, and ammonia.

First, the most important effect of adding ammonia in the present invention will be described.

Through numerous experiments, the present inventor has confirmed that adding ammonia to a paint remover containing commercially available methylene chloride and ethylamine reliably slows down the decrease in the amount of ethylamine in the formulation over time. At the same time, the amount of ammonia added may be small (for example, if ammonia is added at a weight ratio of about 10% to ethylamine in the formulation, the amount of ethylamine in the formulation decreases over time due to the decrease in the amount of ethylamine during preparation). Compared to the case without additives, it was reduced by about 8.3% on the 10th day, about 16.7% on the 20th day, about 25% on the 30th day, and about 33.3% on the 40th day. I learned that the decrease in the amount of ethylamine in the prescription can be suppressed to about 1/2.

Unfortunately, the theoretical elucidation of the effect of adding ammonia has not yet been sufficiently conducted, but as mentioned above, even if ethylamine gradually changes to ethylamine hydrochloride due to the presence of methylene chloride in the formulation, It is estimated that if aqueous ammonia (NH ₄ OH) is present in the sample, ethylamine is gradually liberated from ethylamine hydrochloride, and the liberated ethylamine again exerts the effect of promoting peeling.

In fact, as shown in the examples below, when ammonia is added to a paint trim bar containing methylene chloride and ethylamine,
Even after more than one month has passed since preparation, it maintains a peeling performance practically comparable to that of the baked coating film at the time of preparation.

Furthermore, even if the amount of ammonia added is increased, there is almost no difference in the effect of suppressing the decrease in the amount of ethylamine in the formulation over time from the time of preparation until approximately 20 days (for example, When ammonia was added at a weight ratio of approximately 26% to the ethylamine in the formulation, the amount of ethylamine in the formulation decreased by approximately 8.5% on the 10th day from the time of preparation.
On the 20th day, the decrease was approximately 16.8%. In addition, it decreased by approximately 22.2% on the 30th day and approximately 26.7% on the 40th day. )teeth,
We believe that this supports the above estimation.

Next, the configuration and effects of the present invention will be explained.

The formulation of the paint remover according to the present invention is different from that of the paint remover currently used in Japan, which contains methylene chloride as the main stripping component and ethylamine as the stripping promoting component, except that ammonia is added. Same prescription as above.

The amount of ammonia added may be small; if ammonia is added in an amount of approximately 5% (weight ratio) or more relative to the amount of ethylamine in the formulation, the effect of suppressing the decrease in the amount of ethylamine in the formulation over time is clearly recognized. However, it is practically preferable to add 10 to 30%. When the amount added is 10% (weight ratio) or more relative to the amount of ethylamine in the formulation, there is no difference in effectiveness from the time of preparation until about 20 days, but after that, as the amount of ammonia increases, This makes it possible to more effectively suppress the decrease in the amount of ethylamine in the formulation. However, for the amount of ethylamine in the prescription
Addition of more than 40% (weight ratio) should be avoided as it will have an adverse effect in terms of odor and the like.

Ammonia may be added to the formulation by using a 28% ammonia aqueous solution and calculating the amount of ammonia relative to the amount of ethylamine in the formulation. In this case, the water in the ammonia aqueous solution becomes part of the "3 to 6% water" in the formulation.

Preparation of the paint remover according to the present invention is extremely easy, and a liquid product is obtained by weighing out the required amounts of each compound and thoroughly mixing them. In addition, when mixing, only the paraffin wax is heated and melted in advance.

The prepared liquid product is used by filling it into bottles, cans, etc., or by sealing it into an aerosol can.

The method of use is exactly the same as for commercially available paint removers.

As explained above, the paint remover according to the present invention has a strong peeling ability against baked paint films, and has excellent storage stability, as shown in the examples below. Even after approximately one month has passed, the peeling performance is practically comparable to that of the baked coating film at the time of preparation.

Next, the present invention will be explained using Examples and Comparative Examples.

Example 1 <Formulation> Methylene chloride 72g Monoethylamine 70% aqueous solution 3g Methanol 6g Cellosolve 4g Paraffin wax (softening point 42-44℃) 3g Methylcellulose 2g Sodium alkylbenzenesulfonate 5g Water 3g Ammonia 28% aqueous solution 2g (In the above recipe , ammonia is 26% (weight ratio) to monoethylamine.) <Production method> Add to the solution heated to about 70°C and stirred thoroughly, then add at room temperature and stir thoroughly. , , , , and were added and stirred to prepare a liquid paint remover.

When we measured the decrease in the amount of ethylamine in the formulation of the paint remover obtained here over time, it decreased by 22.2% on the 30th day from the time of preparation, and on the 40th day.
It was a decrease of 26.7%.

On the other hand, for comparison, except for the above formulation,
Using a comparative formulation containing 5g of ethylamine, we measured the decrease in the amount of ethylamine in the liquid paint trim bar prepared by the same procedure as the above manufacturing method over time, and found that it was 43.2% on the 30th day from the time of preparation.
It decreased by 52.7% on the 40th day.

Example 2 Using the <formulation> of Example 1 in which 4 g and 1 g of <formulation> were used (in this prescription, ammonia is 10% by weight relative to monoethylamine), the <manufacturing method> of Example 1 was used. A liquid paint remover was prepared by the same procedure.

When we measured the decrease in the amount of ethylamine in the formulation of the paint remover obtained here over time, it decreased by 25.0% on the 30th day from the time of preparation, and on the 40th day.
It was a decrease of 33.3%.

"Baked paint peeling performance test" Test example 1 <Target baked paint> Epoxy resin paint was applied to a 0.4 mm thick tin plate.
Three test pieces were used, which were coated and baked three times under the conditions of a coating thickness of approximately 25 μm per coat, a baking time of 30 minutes per baking time, and a baking temperature of 180°C.

<Peeling test method> In a room with a room temperature of 18°C and a humidity of 30%, the paint trim bars obtained in Examples 1 and 2 and the paint trim bars with the comparative formulation of Example 1 were tested on each test piece. Apply approximately 1 c.c. of each drop onto the coating surface, and measure the time required for the coating to soften and completely lift from the tin plate surface after the drop is completed, and calculate the peeling time. And so.

<Test Results> The peeling time of each paint trim bar of Examples 1 and 2 and the comparative formulation immediately after preparation was about 45 minutes.

The peeling time of each paint trim bar that had been left indoors for 40 days from the time of preparation was approximately 50 minutes for the paint trim bar of Example 1 and approximately 60 minutes for the paint trim bar of Example 2. In contrast, the paint remover with the comparative formulation took about 100 minutes.

Test example 2 <Target baked coating> Melamine resin paint was applied to a 0.4 mm thick tin plate.
Three test pieces were used, which were coated and baked three times under the conditions of a coating thickness of approximately 25μ per coat, a baking time of 30 minutes per baking time, and a baking temperature of 140°C.

<Peeling test method> Peeling time was determined using the same procedure as in Test Example 1.

<Test Results> The peeling time of each paint trim bar of Examples 1 and 2 and the comparative formulation immediately after preparation was about 30 minutes.

The peeling time of each paint trim bar that had been left indoors for 40 days from the time of preparation was approximately 35 minutes for the paint trim bar of Example 1 and approximately 40 minutes for the paint trim bar of Example 2. In comparison, the paint remover with the comparative formulation took about 60 minutes.

Test example 3 <Target baking coating> Alkyd resin paint was applied to a 0.4mm thick tin plate at a coating thickness of approximately 20μ, baking time of 10 minutes, and baking temperature.
Three test pieces that had been painted and baked once at 175°C were used.

<Peeling test method> Peeling time was determined using the same procedure as in Test Example 1.

<Test Results> The peeling time of each paint trim bar immediately after preparation was 6 minutes and 20 seconds for the paint trim bar of Example 1;
The paint remover of Example 2 and the paint remover of the comparative formulation took 6 minutes.

The peeling time of each paint rim bar left indoors for 40 days from the time of preparation was 6 minutes 20 seconds for the paint rim bar of Example 1, 6 minutes 30 seconds for the paint rim bar of Example 2, and 6 minutes 30 seconds for the paint rim bar of Example 2. Comparative prescription paint rims
The bar was hot for 8 minutes.

Claims (1)

[Scope of Claims] 1. A paint trim bar with excellent storage properties, characterized in that it contains methylene chloride, ethylamine, and ammonia in a weight ratio of 5 to 40% relative to the content of the ethylamine. 2 10 to 10% by weight relative to the content of ethylamine
A paint trim bar with excellent storage stability as described in item 1 containing 30% ammonia.