JPH02269781A - Preparation of aqueous protective composition - Google Patents

Abstract

PURPOSE:To prepare an aq. protective compsn. contg. little alcohol and suitable for primary rust prevention by copolymerizing an alpha,beta-unsatd. acid with a (meth) acrylic ester in an alcohol and subjecting the reaction product to a specific aftertreatment. CONSTITUTION:An alpha,beta-ethylenically unsatd. acid [e.g. maleic acid, (meth)acrylic acid] is copolymerized with a 1-18C alkyl (meth)acrylate in a wt. ratio of (7:93)-(20:80) in a 1-4C satd. monohydric alcohol without the addition of a surfactant. To the resulting reaction product are added water and a volatile alkali (e.g. ammonia, morpholine) in an amt. equivalent to neutralize the acid component, thus giving an aq. protective compsn. having a nonvolatile content of 5-25wt.% and an alcohol content of 5wt.% or lower.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a method for producing an aqueous protective composition suitable for primary rust prevention of painted surfaces, plated surfaces, etc.

[Prior Art] Vehicles such as automobiles, motorcycles, and agricultural cultivators are usually left outdoors before they are delivered to consumers, so their painted surfaces are exposed to dust, soot, etc. deposits due to
Rainwater, corrosive gases in the atmosphere, direct sunlight, etc. often cause the painted surface to become contaminated, discolored, stained, cracked or rusted, resulting in a significant reduction in product value.

As a preventive measure against the above problem, a method has been adopted in which the painted surface of the vehicle is temporarily protected with a wax film and then removed, but if stored for a long time, the wax film deteriorates. This reduces the removability of the coating, and the steam cleaning process in which a petroleum-based solvent is added causes a large amount of oil-containing water to be discharged, which poses a major problem in wastewater treatment.

As a protective composition that eliminates these drawbacks,
There is a composition disclosed in Publication No. 5-505173
The protective composition described in this publication is prepared by copolymerizing a 1, α, β-monoethylenically unsaturated acid and an ester of acrylic acid or methacrylic acid in alcohol without using a surfactant.

It is prepared by adding water to the resulting mixture of reaction products without removing the alcohol from the mixture.

By the way, in general, in an aqueous protective composition, when the alcohol content in the composition exceeds 5% by weight, the composition exhibits a low flash point9. Since the composition contains a vinyl copolymer synthesized in alcohol, the alcohol content m in the resulting aqueous protective composition is ! 0 to 30 weight 1
% or even exceeds 30% by weight, and when actually used, there are safety problems such as fire and explosion, and furthermore, the problem of the alcohol being released into the atmosphere and causing air pollution. The current situation is that

[Problems to be Solved by the Invention] The present invention provides a method for producing an aqueous protective composition containing a vinyl copolymer as an essential component, which has excellent protective properties and removability after long-term storage, and is suitable for wastewater treatment and fire protection. The object of the present invention is to provide a method for producing an aqueous protective composition that does not cause any problems.

Means for Solving Problem E] As a result of extensive research into a manufacturing method for obtaining an aqueous protective composition with a low alcohol content, the present inventors have found that most of the alcohol in the composition can be effectively reduced. The present invention has been completed by discovering a method for producing a protective composition that can be used to protect the skin.

That is, the gist of the present invention is to copolymerize an α,β monoethylenically unsaturated acid and an ester of acrylic acid or methacrylic acid in an alcoholic solvent containing no surfactant, and then distill the alcohol off. The present invention relates to a method for producing an aqueous protective composition characterized in that a volatile alkali and water are simultaneously added while removing the aqueous protective composition.

(α,β-Monoethylenically unsaturated acid) Examples of the α,β-monoethylenically unsaturated acid used in the present invention include maleic acid and fumaric acid.

Examples include crotonic acid, itaconic acid, acrylic acid, and methacrylic acid.

(Ester) Furthermore, as the ester of acrylic acid or methacrylic acid used in the present invention, esters of saturated aliphatic monohydric alcohols having 1 to 18 carbon atoms are suitable, especially esters of saturated aliphatic monohydric alcohols having 1 to 18 carbon atoms. Those with atoms are preferred.

(Blending ratio) The ratio between the unsaturated acid layer 1 and the acrylic acid or methacrylic acid ester layer is 7 to 20%, assuming that the total liter of 1111 bodies is +00ffli%.
It is appropriate that the latter be 80 to 93 balls and 1% by weight.

(Solvent) Alcohol as a solvent used in the present invention is
Lower aliphatic saturated monohydric alcohols having 1 to 4 carbon atoms such as methyl alcohol, propyl alcohol, isopropyl alcohol, n-butyl alcohol, and isobutyl alcohol are suitable.

(Copolymerization Operation) For the above-mentioned copolymerization in an alcohol solvent, it is preferable to use a known and commonly used polymerization initiator, such as a hydroperoxide, dialkyl peroxide, benzoyl peroxide, or an azo compound.

Moreover, when carrying out this copolymerization, if a surfactant is used, the water resistance of the obtained aqueous protective composition film will be deteriorated, so no surfactant is added.

For the copolymerization operation, any known and commonly used technique may be used. That is, the reaction is carried out at normal pressure and at the reflux temperature of the alcohol. Since the reaction rate of copolymerization in alcohol is generally slow, approximately 5 hours are required to complete the copolymerization reaction even after the monomers have been charged. However, in reality, the reaction time is determined depending on the type of monomer used.

(Glass transition point) To protect painted surfaces with the protective composition of the present invention,
It is appropriate that the glass transition point of the coating is from 0 to 50°C, particularly preferably from 10 to 30°C.

If the glass transition point of the film is less than 0°C, the film will become soft and a lot of dirt will adhere to it, and the temperature of the outer skin of a vehicle will reach 80 to 100°C under the hot summer sun, so the film may break. On the other hand, if the glass transition point of the coating exceeds 50°C, it will not be possible to obtain a uniform coating if applied at room temperature, and it will be extremely difficult to remove the coating even if the protective composition is emulsified and applied. Become.

(Removal of alcohol) In the production method of the present invention, after copolymerizing the vinyl monomer mixture in an alcohol solvent, volatile alkali and water are simultaneously added while distilling off the alcohol.
It is necessary to distill off the alcohol until the alcohol content in the resulting copolymer composition reaches 5%. When the alcohol content exceeds 5% by weight, the protective composition exhibits a low flash point, which reduces the safety of work when used as a protective composition.

In the production method of the present invention, the vinyl-based mercury mixture is copolymerized in an alcohol solvent, and then a volatile alkali and water are simultaneously added while distilling off the alcohol for the following reasons.

(1) If alcohol continues to be distilled off without adding a volatile alkali and water, the viscosity of the copolymer solution will gradually increase, and it will eventually become impossible to continue stirring.7 Therefore, only the alcohol can be distilled off. cannot take precedence.

(2) If the volatile alkali is continued to be added while the alcohol is distilled off without adding water, the viscosity of the copolymer solution will gradually increase, eventually making it impossible to continue stirring. Therefore, the alcohol can be distilled off without adding water.

Addition of fugitive alkali cannot continue.

+31 r@If the alcohol is continued to be distilled off while adding water without adding an alkali, the copolymer becomes viscous and precipitates, making 411 stirring difficult. Therefore, it is not possible to continue distilling off alcohol while adding water without adding volatile alkali.

(Neutralization) Furthermore, acid components such as carboxyl groups in the vinyl copolymer are neutralized with a volatile alkali.

Ammonia, morpholine, etc. can be used as the volatile alkali. On the other hand, neutralization with sodium hydroxide, potassium hydroxide, or triethanolamine, which has a slow volatilization rate, is not suitable because the water resistance of the protective film formed will be significantly reduced.

The amount of volatile alkali added needs to be an amount equivalent to the neutralization equivalent of the vinyl copolymer acid component. If the amount of volatile alkali added is less than the neutralization equivalent, the solubility of the 5 copolymer in water will decrease and a homogeneous composition will not be obtained; conversely, the amount of volatile alkali added is too much than the neutralization equivalent In this case, there is no particular good luck, but it is uneconomical.

(a degree) The nonvolatile content concentration of the vinyl copolymer composition thus obtained is preferably 5 to 25% by weight. If the non-volatile content is less than 5% by weight, the film will be thin (and sufficient protective properties will not be obtained).
If it exceeds % by weight, the viscosity of the composition increases, making it difficult to obtain a uniform film, and both are unfavorable.

[Examples] Next, the present invention will be specifically explained with reference to Examples. In the Examples and Comparative Examples, 1 part and % are based on weight unless otherwise specified.

Example 1 100 parts of isopropyl alcohol as a solvent was charged into a reactor equipped with a thermometer, a stirrer, a dropping funnel, a nitrogen gas inlet, and a reflux condenser, and 82 to 8 parts of isopropyl alcohol was charged in a nitrogen stream.
After the temperature was raised to 6°C, 15 parts of acrylic acid, 42.5 parts of butyl acrylate, and 42.5 parts of methyl acrylate were mixed separately as a vinyl thread spool, and this mixture was mixed with peroxide as a polymerization initiator. 1 part of benzoyl was injected dropwise from a separate dropping funnel over a period of 6 hours, and after the completion of the addition, the same temperature was maintained for an additional 6 hours to complete the copolymerization reaction.

Next, while distilling off isopropyl alcohol at a temperature of 82 to 90°C, 14.2 parts of 25% aqueous ammonia and 400 parts of water were added dropwise over 3 hours to obtain the aqueous protective composition of the present invention. Ta.

The amount of isopropyl alcohol distilled off was 86 parts, and the content of isopropyl alcohol in the resulting composition was 2.
7fli! i%, non-volatile concentration is +s, 9! ffi%1, and the flash point of the composition was measured by the Pensky-Martens method.

No flash point was observed.

Next, the protective composition was air-sprayed onto a mild steel plate and dried to form a protective film having a thickness of 10 to 20 LLm. The resulting protective film.

A uniform and transparent film with a glass transition point (measured by differential thermal analysis) of 28° C. was obtained. As a result of investigating various properties of this coating, we found that it has heat resistance (held at 100°C for 24 hours), accelerated weathering resistance (exposed for 300 hours with a sunshine weather meter), weather resistance (exposed outdoors for 1 year), and water resistance (400°C). No change was observed in the film after the test (soaked in distilled water for 24 hours at 60°C), which was extremely good.6 Also, after the above test, the test piece on which the protective film had been formed was heated to about 60°C. 0,
After immersing the sample in a 3% potassium hydroxide aqueous solution for 3 minutes and washing with water, it was also confirmed that the protective film was completely removed within 3 minutes.

Example 2 Into the same reactor as in Example 1, 150 parts of methyl alcohol was charged as a solvent, and 64 to 68 parts of methyl alcohol was charged in a nitrogen stream.
After raising the temperature to ℃, 15 parts of methacrylic acid, 50 parts of ethyl acrylate, and 35 parts of methyl acrylate were mixed separately as a vinyl yarn threader, and this mixture was mixed with 1 part of azobisisobutyronitrile as a polymerization initiator. Department and
The mixture was added dropwise from a separate dropping funnel over a period of 5 hours, and the same temperature was maintained for another 5 hours after the addition route R to complete the copolymerization reaction.

Next, 15.2 parts of morpholine and 300 parts of water were added dropwise over a period of 2 hours while methyl alcohol was distilled off at a temperature of 64 to 70°C to obtain an aqueous protective composition of the present invention.

The amount of methyl alcohol distilled off was 139 parts, and the ring content of methyl alcohol in the resulting composition was 2°6% by weight,
The non-volatile content concentration was 23.4% by weight1, and when the flash point of the composition was measured by the Pensky-Martens method, no flash or defects were observed.

Next, the protective coating of the protective composition was prepared in Example! When the film was formed using the same procedure as above, a uniform and transparent film with a glass transition point of 30° C. was obtained. The various performances of the protective coating were similar to those of Example 1.

Comparative Example 1 A copolymer composition obtained by copolymerizing the same vinyl yarn thread as in Example 1 in an isopropyl alcohol solvent was neutralized with 25% ammonia water to give a nonvolatile content of 18
．． A protective composition was obtained by diluting with water to 6%. The isopropyl alcohol content in the composition was 18.6%, and the flash point according to the Pensky-Martens method was 22°C.

The protective coating formed by the same operating procedure as in Example 1 had a glass transition point of 28° C. and had the same various performances as in Example 1.

Comparative Example 2 A copolymer composition obtained by copolymerizing the same vinyl yarn thread as in Example 2 in a methyl alcohol solvent was neutralized with morpholine to a nonvolatile content of 23.4%. A protective composition was obtained by diluting with water until the composition was saturated.

The methyl alcohol content in the composition is 35.1%
The flash point according to the Pensky Martens method is 15°C.
Met.

The protective coating formed by the same operating procedure as in Example 1 had a glass transition point of 30° C. and had the same various performances as in Example 1.

[Effects of the Invention] The aqueous protective composition obtained by the method of the present invention exhibits excellent protective properties particularly for primary rust prevention of automobiles, vehicles, mechanical parts, etc., and can provide stable protection over a long period of time. At the same time, there is no problem with fire, and it is easy to remove the film and treat wastewater, so the work can be streamlined.
Furthermore, it has the advantage of not destroying the natural environment.

Applicant: Koushiro Chemical Industry Co., Ltd.

Claims (8)

[Claims] (1) After copolymerizing an α,β-monoethylenically unsaturated acid and an ester of acrylic acid or methacrylic acid in an alcohol solvent that does not contain a surfactant, while distilling off the alcohol, A method for producing an aqueous protective composition, characterized in that an alkali and water are added at the same time. (2) Production of the aqueous protective composition according to claim 1, wherein the blending ratio of the α,β-monoethylenically unsaturated acid and the ester of acrylic acid or methacrylic acid is 7 to 20 to 93 to 80 by weight. Method. (3) Acrylic acid or methacrylic acid ester is 1
2. The method for producing an aqueous protective composition according to claim 1, which is an ester of a saturated aliphatic monohydric alcohol having 1 to 18 carbon atoms. (4) The method for producing an aqueous protective composition according to claim 1, wherein the alcohol solvent is a saturated monohydric alcohol having 1 to 4 carbon atoms. (5) The method for producing an aqueous protective composition according to claim 1, wherein the film formed by the aqueous protective composition has a glass transition point of 0 to 50°C. (6) The method for producing an aqueous protective composition according to claim 1, wherein the amount of volatile alkali used is equivalent to neutralizing the acid component of the copolymer. (7) The method for producing an aqueous protective composition according to claim 1, wherein the nonvolatile content of the aqueous protective composition is 5 to 25% by weight. (8) The alcohol content in the aqueous protective composition is 5% by weight or less, and the nonvolatile content is 5 to 25% by weight.
% by weight. The method for producing an aqueous protective composition according to claim 1.