JPH03237172A - Primary paint surface protection composition that can be removed using an alkaline aqueous solution - Google Patents

Abstract

PURPOSE:To provide the subject composition giving coating films which have excellent acid resistance and UV-shielding effect and can be erased with an alkali aqueous solution by neutralizing a specific acrylic copolymer with a volatile water-soluble basic compound and subsequently adding a specific amount of a polyvalent metal salt to the neutralization product. CONSTITUTION:A copolymer is neutralized with a volatile water-soluble basic compound (e.g. ammonia or methyl amine) and subsequently compounded with 0.3-4.5wt.% (based on the copolymer) of a polyvalent metal salt (preferably Ca, Mg or Zn salt) to provide the objective composition, the copolymer being prepared by copolymerizing an alpha,beta-monoethylenic unsaturated acid [preferably (meth)acrylic acid] preferably in an amount of 10-20wt.%, an acrylic ester (e.g. methyl acrylate) preferably in an amount of 20-60wt.% and a methacrylic ester (e.g. methyl methacrylate) preferably in an amount of 30-60wt.% in water.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a water-based paint surface protection composition, and more specifically, to a composition that blocks ultraviolet rays when a vehicle exterior panel is exposed outdoors for a long period of time. The present invention relates to a composition for protecting painted surfaces that has the effect of protecting a painted surface and is not easily affected by acidic substances. INDUSTRIAL APPLICATION This invention is utilized for vehicles, such as an automobile, a motorcycle, and an agricultural tiller.

[Conventional technology]

Vehicles such as automobiles are often left outdoors until they are delivered to the consumer. For this reason, the exterior paint surface may discolor, smear, or bleed due to deposits such as dust and soot, rainwater, corrosive gases in the atmosphere, or direct sunlight containing ultraviolet rays.
In many cases, matting, cracking, rusting, etc. occur, resulting in a significant decrease in commercial value.

Conventional methods to prevent this have been to temporarily protect the painted surface of the vehicle exterior with a wax film and then remove it (5), but this is difficult to remove if the vehicle has been stored for a long period of time. It has the disadvantage of becoming A protective composition that eliminates such drawbacks is a composition prepared by copolymerizing α,β-monoethylenically unsaturated acid and an ester of acrylic acid or methacrylic acid in alcohol and adding water (Japanese Patent Publication No. -50517) is known.

[Problem to be solved by the invention]

However, if the coated surface coated with the wax or protective composition described above is exposed to ultraviolet light for a long period of time, the coating resin will oxidize and depolymerize as this coating film has little effect of blocking ultraviolet light. This may cause embrittlement such as so-called matting. In addition, dyes and pigments contained in paints may also be oxidized in the air by ultraviolet light, causing their conjugated systems to break down and cause fading or whitening of the paint.

Further, the above-mentioned conventional protective compositions have the problem that they are easily affected by acidic substances, and in particular, painted surfaces are easily damaged by acid rain and acid soot. Furthermore, since the above-mentioned protective composition contains alcohol, there is a problem in terms of fire or air pollution when used.

The present invention has been made in view of the above-mentioned viewpoints, and an object of the present invention is to provide a composition for protecting a painted surface that has an excellent ultraviolet blocking effect and is less likely to be adversely affected by acidic substances.

[Means to solve the problem]

As a result of extensive research into the protective performance of vehicle exterior painted surfaces, especially how ultraviolet rays and acidic substances affect the protective film, the inventors found that α,β-monoethylenically unsaturated A copolymer made by copolymerizing a monomer consisting of an acid, an acrylic ester, and a methacrylic ester in water is neutralized with a volatile base compound, and then a polyvalent metal salt is added. A composition in which the amount of the valent metal salt added is 0.3 to 4.5% by weight based on the copolymer,
We have completed the present invention by discovering that it has excellent performance for protecting painted surfaces, especially excellent ultraviolet blocking effect and acid resistance.

As the "α,β-monoethylenically unsaturated acid" in the present invention, maleic acid, fumaric acid, itaconic acid, crotonic acid, acrylic acid, methacrylic acid, etc. can be used, but among these, acrylic acid Alternatively, it is desirable to use methacrylic acid. In addition, examples of the "acrylic ester" include methyl acrylate, ethyl acrylate,
N-butyl acrylate and the like can be used. Examples of the "methacrylic ester" include methyl methacrylate, ethyl methacrylate, n-butyl methacrylate,
T-butyl methacrylate and the like can be used.

In addition, the blending ratio of monomers in the “copolymer” is as follows:
As shown in the second invention, α,β-monoethylenically unsaturated acid is 10 to 20% by weight, and acrylic ester is 20 to 20% by weight.
60% by weight, 30-60% by weight of methacrylic acid ester
It is desirable that In this case, the film has excellent removability with an alkaline aqueous solution. In particular, α, β
- If 7% by weight of the monoethylenically unsaturated acid is present in the copolymer, it is difficult to remove this film with an alkaline aqueous solution.

In addition, acrylic esters and methacrylic esters are
As shown in the third aspect of the present invention, it is preferable that all of them are saturated aliphatic hydrocarbon monovalent alcohol esters having 1 to 18 carbon atoms.

Water-soluble volatile basic compounds that neutralize the acid contained in the above-mentioned "copolymer" include ammonia, methylamine, dimethylamine, ethylamine, diethylamine, morpholine, and other water-soluble volatile base compounds that have a lower boiling point and higher volatility than triethanolamine. One or more types of basic compounds can be used.

On the other hand, when neutralized with sodium hydroxide, potassium hydroxide, or triethanolamine, which has a slow volatilization rate,
This is not suitable because the water resistance of the protective film formed will be reduced. The amount of the basic compound to be added may be close to or above the neutralization of acidic components, but as shown in the fourth aspect of the present invention, an amount corresponding to the neutralization equivalent is preferable. If the amount is too small than the neutralization equivalent of the acid component, the solubility of the copolymer in water will decrease, while if it is too large, monoethylenically unsaturated acids such as acrylic acid will become more easily soluble in water, leading to a decrease in copolymerization. This is because the dispersion of substances becomes non-uniform, which is not preferable.

As the "polyvalent metal salt", salts of zinc, aluminum, copper, calcium, magnesium, zirconium, barium, aluminum, etc. can be used. In this case, especially calcium, magnesium or zinc salts are preferred. This polyvalent metal salt is preferably water-soluble, but is not limited thereto. It is preferable to add a dispersant to this non-water-soluble material. The amount of the polyvalent metal salt added is 0.3 to 4.5% by weight based on the copolymer. If the amount added is less than 0.3% by weight, sufficient ultraviolet blocking effect cannot be obtained;
This is because if it exceeds % by weight, the film-forming ability decreases and the protective film becomes brittle, which is undesirable.

Also, "neutralize with a basic compound and add a polyvalent metal salt"
This does not mean that the order of addition is particularly restricted, and one may be added first or one may be added at the same time.

In addition, in the painted surface protection composition of the present invention, in order to improve coating workability and weather resistance, plasticizers, coalescing agents, antifoaming agents,
Leveling agents, lubricants, anti-sagging agents, light stabilizers, and/or
Alternatively, an antioxidant or the like may be added.

E effect] Since this composition uses a copolymer consisting of α,β-monoethylenically unsaturated acid, acrylic ester, and methacrylic ester, it has excellent film performance and
Excellent film removability with alkaline aqueous solution. In addition, since the acid contained in this copolymer is neutralized with a water-soluble basic compound that is easily removed by volatilization, it is neutralized and no basic compound remains in the coating, so the coating has excellent properties and is easy to apply. There is little impact on the surface.

Furthermore, the present composition contains a predetermined amount of polyvalent metal salt. Therefore, when this composition is applied to a painted surface, metal atoms are uniformly distributed in the coating, which reflects ultraviolet rays and prevents the ultraviolet rays from transmitting to the painted surface. For this reason,
Prevents paint film from deteriorating due to ultraviolet rays. Furthermore, since it similarly contains a polyvalent metal salt, acid resistance is also improved. Furthermore, since the atomic radius of the metal atoms in the polyvalent metal salt is relatively large,
This effect can also be achieved by adding a small amount of polyvalent metal salt.

〔Example〕

The present invention will be specifically explained below using Examples.

(1) Preparation of painted surface protection composition (a) Preparation of copolymer The copolymer compositions A to E in this example were prepared by emulsion polymerization or solution polymerization as described below.

(a) In the case of emulsion polymerization method, polyoxyethylene alkyl ether sulfate (alkyl group: CI2
~C8) 0.6 parts by weight and 1.5 parts by weight of polyoxyethylene phenyl ether (number of moles of ethylene oxide added: 12 moles) were added, and further 0.1 parts by weight of ammonium persulfate was added as a polymerization initiator, Then 73℃～7
The temperature was raised to 8°C.

Next, 34 parts by weight of the monomer mixture was added dropwise over a period of 180±10 minutes for polymerization. After the polymerization is completed, 50-6
The mixture was cooled to 0t, 3 parts by weight of aqueous ammonia (25% by weight) was added, and calcium carbonate was added dropwise over 30±10 minutes.

The composition of the monomer mixture used in the above polymerization is shown in Table 1. The numbers in the table indicate parts by weight. Further, copolymer compositions ASB, D, and E in the same table indicate those having the respective monomer compositions listed in the same table and a solid content (copolymer) concentration of 35% by weight.

(For the solution polymerization method: 10 parts by weight of the monomer mixture and 10 parts by weight of ethanol were charged, the temperature was raised to 75 to 80°C, and then 1 part by weight of benzoyl peroxide was added. mixture 4
A mixture of 0 parts by weight and 40 parts by weight of ethanol was added to 300±
It took 30 minutes to add dropwise and polymerize. After the polymerization is finished,
Cool to 50-60°C and add ammonia water (25% by weight) 3
parts by weight were added.

The composition of the monomer mixture used in the above polymerization is shown in Table 1. Moreover, the numerical values in the table indicate parts by weight.

Copolymer composition C refers to monomer M listed in the same table, with a solid content (copolymer) of 50% by weight.

(b) Preparation of painted surface protection composition Examples 1 to 8 Each copolymer composition, calcium carbonate, aqueous ammonia, and water were blended in the proportions shown in Table 2.
Painted surface protection compositions were prepared. However, the numerical values indicating the composition in Table 2 are in weight %.

(c) Preparation of Comparative Example Product Copolymer composition A or C1 calcium carbonate similar to that of the example was prepared in the proportions shown in Table 3 (however, Comparative Example 1
．． 6 does not include this. >, ammonia water, and water were blended to prepare painted surface protection compositions according to Comparative Examples 1 to 6, respectively. In addition, the numerical values showing the composition in Table 3 are weight %.

(2> Performance test and evaluation In order to clarify the performance of this painted surface protection composition, the second
The following performance tests were conducted on the compositions listed in Tables 3 and 3, and the evaluations are shown in Table 4.

(a) Protective coated test piece (black solid) with a dry film thickness of 10μ
After coating each sample (compositions of Examples 1 to 8 and Comparative Examples 1 to 6) so that
m) was continuously irradiated for 4 weeks. Next, apply 1% to the coated surface.
The protective properties were evaluated by examining changes in the color and gloss of the painted surface when wiped with aqueous ammonia, and the results are shown in Table 4.

The performance evaluation display in Table 4 is as follows: ◎: No change, ○: Slight change, △: Change, X: Change/matting, ×
×: Represents significant change and matte appearance, respectively.

(b) Removability test piece (S[JS 301: I!!Erased finish),
After each sample (compositions of Examples 1 to 8 and Comparative Examples 1 to 6) was applied so that the dry film thickness was 5 μm, ultraviolet rays (253, 'tnm>) were continuously irradiated for 4 weeks. The test piece was immersed in Alka IJ & purified water solution at 20°C, and the immersion time (seconds) until the film was completely removed was measured.

The composition of the alkaline cleaning aqueous solution used here was 6% by weight of aqueous ammonia, 3% by weight of sodium metasilicate, 02% by weight of sodium ethylenediaminetetraacetate, and polyoxyethylene alkyl ether (alkyl group: 61.~C1).
1. Number of moles of ethylene oxide added: 9 moles) 1% by weight and 89.8% by weight of water.

The performance evaluation indicators in Table 4 are as follows: ○: Removal time 50 seconds or less, ×: Removal time 200 seconds or more.

(c) Samples (compositions of Examples 1 to 8 and Comparative Examples 1 to 6) were applied to the same black coated board as used for the evaluation of acid resistance protection so that the dry coating film was 10 μm. Apply and dry at 60°C for 10 minutes. Next, dilute sulfuric acid water adjusted to pH 3 02~
A voltage of 0.3 mA was spot-dropped onto the coated plate, the test piece was left horizontal at 60° C. for 24 hours, and the condition of the spot surface when wiped with 1% ammonia water was observed and evaluated.

In addition, the performance evaluation display in Table 4 is as follows: ◎: No change, ○: Slight change, △: Change, ×: Painted surface peeling, XX,
Represents paint surface peeling.

(3) Effects of Examples As shown in Table 4, using a copolymer with a predetermined monomer composition and neutralizing with easily volatile aqueous ammonia, the amount of calcium carbonate added was 0.4. -3.0% by weight Examples 1 to 8 were particularly excellent in ultraviolet protection and acid resistance compared to comparative examples, that is, they were excellent in all aspects of protection, removability, and acid resistance, and were very well balanced. good. Among them, Example 2
．． When the amount of calcium carbonate added is relatively large, such as 3.0% by weight, as in No. 6, the protective properties are particularly excellent.

On the other hand, in Comparative Examples 1 to 4.6, the amount of calcium carbonate added was small at 0.3% by weight or less, so the removability was the same as that of the example product, but the protection property and acid resistance were inferior. . On the other hand, in Comparative Example 5, the amount of calcium carbonate added was as high as 5% by weight, so the protective property was equivalent to that of the Example product, but the removability was inferior.

It should be noted that the present invention is not limited to those shown in the above-mentioned specific embodiments, and may be modified in various ways within the scope of the present invention depending on the purpose and use.

〔Effect of the invention〕

By using the composition for protecting painted surfaces of the present invention, it is possible to obtain a film that has excellent acid resistance and a sufficient effect of blocking ultraviolet rays, and can be used outdoors for a long time after painting! ! Even after exposure, the film can be easily removed with an aqueous alkaline solution. Therefore, by using this composition, it is possible to maintain the quality of vehicle exterior panels, as well as improve product quality and workability, especially in today's world where acid rain and acid soot are problems. Therefore, the significance of the present invention is great.

Furthermore, since the composition is water-based, there are significantly fewer concerns about fire or air pollution than when alcohol is used.

Claims (4)

[Claims] (1) Neutralizing a copolymer obtained by copolymerizing a monomer consisting of an α,β-monoethylenically unsaturated acid, an acrylic ester, and a methacrylic ester in water with a volatile water-soluble basic compound, 1. A paint surface protection composition comprising a polyvalent metal salt added thereto, wherein the amount of the polyvalent metal salt added is 0.3 to 4.5% by weight based on the copolymer. (2) The blending ratio of α, β-monoethylenically unsaturated acid, acrylic ester, and methacrylic ester is
The composition for protecting painted surfaces according to claim 1, wherein the monoethylenically unsaturated acid is 10 to 20% by weight, the acrylic ester is 20 to 60% by weight, and the methacrylic ester is 30 to 60% by weight. (3) The composition for protecting painted surfaces according to claim 1, wherein the acrylic ester and the methacrylic ester are both esters of C_1 to C_1_0 saturated aliphatic hydrocarbon monohydric alcohol. (4) The composition for protecting painted surfaces according to claim 1, wherein the amount of the volatile basic compound used is the equivalent of neutralizing the acidic content of the copolymer.