JPH0655923B2 - Aqueous protective composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of use] The present invention relates to a method for producing an aqueous protective composition suitable for primary rust prevention on a painted surface, a plated surface and the like.

[Prior Art] Most of vehicles such as automobiles, motorcycles, and cultivators for agriculture are usually left outdoors until they reach a customer. Therefore, the coated surface is not covered with dust or dust. Kimono, rainwater, corrosive gas in the atmosphere, direct sunlight, etc. often cause contamination, discoloration, stains, gloss, cracks or rust on the coated surface, resulting in a marked decrease in commercial value.

As a measure to prevent the above problems, a method of protecting the painted surface of the vehicle with a wax film and then removing it each time is also adopted, but when stored for a long time, the removal property of the film is deteriorated due to the deterioration of the wax film. In addition, the amount of oil-containing water is discharged in a steam cleaning process in which a petroleum solvent is added, which causes a big problem in wastewater treatment. As a protective composition eliminating these drawbacks, Japanese Patent Publication No. 55-50
There are compositions disclosed in No. 517. The protective composition is synthesized by a method of copolymerizing an α, β-monoethylenically unsaturated acid and an ester of acrylic acid or methacrylic acid in an alcohol that does not use a surfactant.

By the way, generally, in an aqueous protective composition, when the alcohol content in the composition exceeds 5% by weight, the composition exhibits a low flash point. Since the above publicly disclosed aqueous protective composition synthesizes a vinyl-based copolymer in alcohol, the content of alcohol in the obtained aqueous protective composition is 10 to 30% by weight, or 3
When it exceeds 0% by weight, it may cause a safety problem such as a fire or an explosion when it is actually used, and further, the alcohol may be released into the atmosphere and cause air pollution. The current situation.

[Problems to be Solved by the Invention] The present invention provides an aqueous protective composition containing a vinyl-based copolymer as an essential component, which has excellent protective properties and removability after long-term storage, and has problems of wastewater treatment and fire. It is an object of the present invention to provide a method for producing a non-aqueous protective composition.

[Means for Solving Problems] As a result of intensive studies on a polymerization method in order to improve a conventional aqueous protective composition, the present inventors have solved the above-mentioned drawbacks and have excellent protective properties. The present invention has been completed by finding out an aqueous protective composition having the same.

That is, the gist of the present invention is (first step): (a) an α, β-monoethylenically unsaturated acid; and (b) an ester of acrylic acid or methacrylic acid, which is volatilized without a surfactant. Copolymerization in an organic solvent (second step), an amount of a volatile alkali and water necessary for neutralizing the acid component of the copolymer (c) obtained in the first step is added to form an aqueous solution, (Third step) Aqueous solution obtained by adding (d) α, β-monoethylenically unsaturated acid and (e) ester of acrylic acid or methacrylic acid to the aqueous solution obtained in the second step and copolymerizing It relates to a protective composition.

(Α, β-Monoethylenically Unsaturated Acid) Examples of the α, β-monoethylenically unsaturated acid used in the present invention include maleic acid, fumaric acid, crotonic acid, itaconic acid, acrylic acid and methacrylic acid. Can be mentioned.

The α, β-monoethylenically unsaturated acids (a) and (d) may be the same or different.

(Ester) The ester of acrylic acid or methacrylic acid used in the present invention has 1 to 18 carbon atoms.
Are suitable, especially aliphatic saturated monohydric alcohols having 1 to 4 carbon atoms.

In addition, acrylic acid or methacrylic acid ester (b)
And (e) may be the same or different.

(Blending ratio) The amount of the unsaturated acid used and the amount of the acrylic acid or methacrylic acid ester used is in the range of 7 to 20 parts by weight of the former and 80 to 93 parts by weight of the latter. Appropriate.

The compounding ratios of (a) and (b) and (d) and (e) may be the same or different.

(Copolymerization Operation) In the production method of the present invention, in both the first step and the third step, the α, β-monoethylenically unsaturated acid and the ester of acrylic acid or methacrylic acid are charged in the reaction vessel in the total amount. After that, the reaction can be started.

Alternatively, there is also a method of carrying out the reaction while dropping both of the above monomers into a reaction vessel, and the latter method is suitable.

The copolymerization operation is preferably carried out using a known and commonly used polymerization initiator, for example, an organic peroxide such as hydroperoxide or benzoyl peroxide or an azo compound in the first step,
Further, in the third step, it is preferable to use an inorganic peroxide such as hydrogen peroxide or persulfate.

If a surfactant is used in the case of copolymerization, the water resistance of the resulting aqueous protective composition coating will be poor, so no surfactant is added.

The reaction in the first step is carried out at a temperature at which the volatile solvent is refluxed, and the reaction time requires several hours after the charging of each monomer is completed. On the other hand, the reaction in the third step is carried out at a temperature of 60 to 90 ° C., and the reaction time is 1 to 2 hours after the charging of each monomer is completed.

(Volatile Solvent) In the production method of the present invention, as the volatile solvent used in the first step, a lower saturated one having 1 to 4 carbon atoms such as methyl alcohol, propyl alcohol, isopropyl alcohol, n-butyl alcohol, isobutyl alcohol and the like. A monohydric alcohol, methyl ethyl ketone, cellosolve, etc. can be used.

The content of the volatile solvent in the aqueous protective composition obtained by the present invention is preferably 5% by weight or less.

(Solubility) The volatile alkali and water in an amount necessary to neutralize the acid component in the copolymer (c) obtained by the copolymerization in the above-mentioned first step are added to form an aqueous solution. Used in the process.

In the production method of the present invention, the acid component in the copolymer (c) is neutralized with a volatile alkali such as ammonia or morpholine. On the other hand, neutralization with sodium hydroxide, potassium hydroxide, triethanolamine having a slow volatilization rate, etc. is not optimal because the water resistance of the formed film is significantly reduced.

The amount of volatile alkali added is the vinyl polymer (c).
The amount must be equivalent to the neutralization equivalent of the acid component of. When the addition amount of the volatile alkali is less than the acid component of the vinyl polymer (c), the solubility of the copolymer in water is lowered.

On the other hand, when a volatile alkali is used in an amount larger than the neutralization equivalent of the acid component of the copolymer (c), the α, β-monoethylenically unsaturated acid is dissolved in water and the copolymerization reaction becomes nonuniform. This is not desirable.

(Amount of Copolymer (c) Used) In the third step, the amount of the copolymer (c) must be 2 to 10% by weight based on the total amount of (c), (d) and (e). . If the ratio of (c) to the total amount of (c), (d) and (e) is less than 2% by weight, (d) and (e)
As a result, a copolymer is precipitated and a uniform composition cannot be obtained. On the other hand, when the proportion of (c) is more than 10% by weight with respect to the total amount of (c), (d) and (e), the content of the volatile solvent in the obtained aqueous protective composition increases. , Not preferable.

(Content of Volatile Solvent) The content of the volatile solvent in the aqueous protective composition is 5% by weight.
Must be less than. If it exceeds 5% by weight, the composition shows a low flash point, which is not preferable.

(Glass Transition Point of Coating) To protect the coated surface with the protective composition of the present invention,
The glass transition point of the coating is 0 to 50 ° C, especially 1
It is preferably 0 to 30 ° C. If the glass transition point of the coating is less than 0 ° C, the coating becomes soft and a large amount of earth and sand adheres to it. Also, in hot summer weather, the vehicle outer panel temperature reaches 80 to 100 ° C, so the coating is cut off. Happens. On the other hand, if the glass transition temperature of the coating exceeds 50 ° C, a uniform coating cannot be obtained by coating at room temperature,
Even if the protective composition is emulsified and applied, it becomes white powder and cannot form a film. Further, even if a film is formed, it is very difficult to remove the film.

EXAMPLES Next, the present invention will be specifically described by showing examples, but the present invention is not limited to the following examples. In Examples and Comparative Examples, parts and%
Is weight basis unless otherwise specified.

Example 1 A reactor equipped with a thermometer, a stirrer, a dropping funnel, a nitrogen gas inlet and a reflux condenser was charged with 100 parts of isopropyl alcohol as a solvent, and 82 to 8 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 separately mixed as vinyl monomers, and this mixture and 1 part of benzoyl peroxide were separated. 5 from the dropping funnel
It took time to inject dropwise and copolymerize. After the dropping was completed, the temperature was kept at the same temperature for 5 hours to complete the copolymerization reaction.

Next, after the obtained vinyl-based copolymer solution was cooled to room temperature, 14.2 parts of 25% -concentrated ammonia water was added dropwise, and water was added until the nonvolatile concentration became 5%.

Then, the aqueous vinyl copolymer solution 15 thus obtained
0 part (7.5 parts as copolymer (c)) was charged into another reactor, 0.3 part of potassium persulfate was added, and the temperature was raised to 75 to 80 ° C. in a nitrogen stream, and then vinyl-based. 15 parts of acrylic acid and 4 parts of butyl acrylate as monomers
2.5 parts, 42.5 parts of methyl acrylate, and 102 parts of a mixture of 2 parts of dodecyl mercaptan as a polymerization degree adjusting agent were added dropwise over 3 hours.

After the dropping was completed, the temperature was kept at the same temperature for 2 hours to complete the copolymerization reaction to obtain the aqueous protective composition of the present invention. In addition,
The ratio of (c) to the total amount of (c), (d) and (e) is 7.0%.

The content of isopropyl alcohol in the obtained aqueous protective composition was 3.0%, and when the flash point of the composition was measured by the Penschemultens method, no flash point was observed.

Next, the composition is neutralized with ammonia, diluted with water to a nonvolatile concentration of 20%, air-sprayed on a mild steel plate, and dried to form a protective film having a thickness of 10 to 20 μm. It was

The protective film obtained had a glass transition point (measured by differential thermal analysis) of 28 ° C., and a uniform and transparent film was obtained. As a result of examining various properties of this coating, heat resistance (holding at 100 ° C. for 24 hours), advancement weathering resistance (3 with a sunshine weather meter)
00 hours), weather resistance (outdoor exposure for 1 year), and water resistance (immersion in distilled water at 40 ° C for 24 hours),
No change was observed in the coating film after the test, which proved to be extremely good. Further, each test piece having a protective coating formed after the above test was immersed in a 0.3% aqueous potassium hydroxide solution heated to about 60 ° C. for 3 minutes and then washed with water. It was also confirmed that it was completely removed in time.

Example 2 In a reactor similar to that of Example 1, 80 parts of methyl alcohol was charged as a solvent, the temperature was raised to 64 to 68 ° C. in a nitrogen stream, and then 15 parts of methacrylic acid and ethyl acrylate were separately used as vinyl monomers. And 35 parts of methyl acrylate were mixed in advance, and this mixture and 1 part of azoisobutyronitrile as a polymerization initiator were added dropwise from separate dropping funnels over 5 hours to carry out copolymerization. .

Next, the obtained vinyl-based copolymer solution was cooled to room temperature, 15.2 parts of monophorine was added dropwise, and water was added until the concentration of nonvolatile components became 10% by weight.

Then, the aqueous vinyl copolymer solution 10 thus obtained
0 part (10 parts as the copolymer (c)) was charged into another reactor, 0.3 part of potassium persulfate was added, and the temperature was raised to 75 to 80 ° C. in a nitrogen stream, then 10 parts of methacrylic acid was added.
Parts, 20 parts of methyl acrylate, 7 parts of ethyl acrylate
102 parts of a mixture consisting of 0 part and 2 parts of dodecyl mercaptan as a polymerization regulator was added dropwise over 3 hours. Even after the completion of the dropping, the copolymerization reaction was completed by keeping the same temperature for 2 hours to obtain the aqueous protective composition of the present invention. In addition,
The ratio of (c) to the total amount of (c), (d) and (e) was 4.8%.

The content of methyl alcohol in the obtained aqueous protective composition was 4.0%, and the flash point of the composition was measured by the Penschemaltens method, and no flash point was observed.

Then, the composition was neutralized with morpholine, and a protective coating of the protective composition obtained by diluting the composition with water until the concentration of non-volatile components reached 20% was formed by the same procedure as in Example 1. As a result, the glass transition point of the coating was 10 ° C., and a uniform and transparent coating was obtained. The properties of this coating were the same as in Example 1.

Comparative Example 1 A copolymer composition obtained by copolymerizing 100 parts of a vinyl-based monomer similar to that used for copolymerization in isopropyl alcohol in Example 1 in a solvent of 100 parts of isopropyl alcohol was treated with 25% ammonia. The mixture was neutralized with water and diluted by adding water until the concentration of non-volatile components reached 20% to obtain a protective composition.

The isopropyl alcohol content in the composition was 20.
%, And the flash point by the Pennsylmartens method is 27.
It was ℃.

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

Comparative Example 2 A copolymer composition obtained by copolymerizing 100 parts of the same vinyl-based monomer used for copolymerization in the aqueous solution of Example 2 in 150 parts of methyl alcohol as a solvent was neutralized with morpholine. Then, water was added to dilute the solution until the nonvolatile content concentration became 20% to obtain a protective composition.

The methyl alcohol content in the composition was 30%, and the flash point by the Penschemaltens method was 23 ° C.

The protective coating formed by the same procedure as in Example 1 had a glass transition point of 10 ° C. and various performances as in Example 1.

[Effects of the Invention] The aqueous protective composition obtained by the production method of the present invention comprises:
In particular, it exhibits excellent protection properties for temporary rust prevention of automobiles, vehicles, machine parts, etc., can be stably protected for a long period of time, there is no problem of fire, and it is easy to remove the coating and wastewater treatment, It has the advantages of streamlining work and not destroying the natural environment.

Claims (7)

[Claims] 1. A first step, wherein (a) an α, β-monoethylenically unsaturated acid and (b) an ester of acrylic acid or methacrylic acid are mixed in a volatile solvent containing no surfactant. Polymerization (second step) Add an amount of volatile alkali and water necessary for neutralizing the acid component of the copolymer (c) obtained in the first step to form an aqueous solution (third step) In the aqueous solution obtained in the second step, (d) α, β
An aqueous protective composition comprising a composition obtained by adding and copolymerizing a monoethylenically unsaturated acid and (e) an ester of acrylic acid or methacrylic acid. 2. The aqueous solution according to claim 1, wherein the esters (b) and (e) of acrylic acid or methacrylic acid are both esters of a saturated aliphatic monohydric alcohol having 1 to 18 carbon atoms. Protective composition. 3. The aqueous protective composition according to claim 1, wherein the blending ratio of (a) and (b) and the blending ratio of (b) and (e) are 7 to 20:80 to 93. 4. The aqueous protective composition according to claim 1, wherein the volatile solvent is a saturated monohydric alcohol having 1 to 4 carbon atoms, methyl ethyl ketone, and cellosolve. 5. The aqueous protective composition according to claim 1, wherein the ratio of (c) to the total weight of (c), (d) and (e) is 2 to 10% by weight. 6. The aqueous protective composition according to claim 1, wherein the content of the volatile solvent in the aqueous protective composition is 5% by weight or less. 7. The aqueous protective composition according to claim 1, wherein the glass transition point of the film formed by the aqueous protective composition is 0 to 50 ° C.