JPH0822989B2 - Composition for removing primary coating surface with alkaline aqueous solution - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a composition for protecting a removable primary coating surface with an alkaline aqueous solution, and more specifically, when the vehicle skin is exposed outdoors for a long period of time. The present invention relates to a composition for protecting a painted surface, which has an effect of blocking ultraviolet rays and is hardly affected by an acidic substance. INDUSTRIAL APPLICABILITY The present invention is used in vehicles such as automobiles, motorcycles, and agricultural tillers.

[Conventional technology]

Vehicles such as automobiles are often left outdoors until they reach consumers. For this reason, discoloration, bleeding, gloss, cracks, rust, etc. may occur on the outer panel coating surface due to dust or dust deposits, rainwater, corrosive gas in the atmosphere, or direct sunlight containing ultraviolet rays. It is not uncommon for product value to drop significantly.

As a preventive measure against these problems, a method has been conventionally adopted in which the coated surface of the vehicle outer panel is temporarily protected with a wax film and then removed, but it becomes difficult to remove it when it is stored for a long period of time. It has the drawback of As a protective composition that eliminates such drawbacks, a composition obtained by copolymerizing α, β-monoethylenically unsaturated acid and an ester of acrylic acid ester or methacrylic acid in alcohol and adding water (Japanese Patent Publication No. 55 -50517) is known.

[Problems to be Solved by the Invention]

However, when the coating surface coated with the above wax or protective composition is exposed to ultraviolet rays for a long period of time, this coating film has almost no effect of blocking ultraviolet rays, so that the coating resin is oxidized and depolymerized. May cause embrittlement such as so-called gloss. Further, the dyes and pigments contained in the paint may also be air-oxidized by ultraviolet rays, destroying the conjugated system thereof and causing fading or whitening of the paint.

Further, the above conventional protective composition has a problem that it is likely to be adversely affected by an acidic substance, and in particular, the coated surface is easily damaged by acidic rain or acidic soot. Furthermore, since the above-mentioned protective composition contains alcohol, there is a problem in terms of fire or air pollution during use.

The present invention has been made in view of the above viewpoints, and an object of the present invention is to provide a removal-type primary coating surface protection composition with an alkaline aqueous solution, which has an excellent effect of blocking ultraviolet rays and is less likely to be adversely affected by an acidic substance.

[Means for solving the problem]

The inventors of the present invention have earnestly studied about the protective performance of a vehicle outer panel coating surface, in particular, how ultraviolet rays and acidic substances affect a protective film, and as a result, α, β-monoethylenically unsaturated at a predetermined mixing ratio. A copolymer obtained by copolymerizing a monomer consisting of an acid, an acrylic ester and a methacrylic ester in water is neutralized with a volatile basic compound, and then a calcium salt, magnesium or barium salt is added. , A composition in which the amount of the salt added is 0.3 to 4.5% by weight with respect to the copolymer, excellent performance for protecting the painted surface,
The present invention has been completed by finding that they have a particularly excellent ultraviolet blocking effect and acid resistance.

"Α, β-monoethylenically unsaturated acid" in the present invention
As the acid, maleic acid, fumaric acid, itaconic acid, crotonic acid, acrylic acid, methacrylic acid or the like can be used, and among these, acrylic acid or methacrylic acid is particularly preferable. Moreover, as said "acrylic acid ester", methyl acrylate, ethyl acrylate, acrylic acid-n-butyl, etc. can be used.
As the "methacrylic acid ester", methyl methacrylate, ethyl methacrylate, -n-butyl methacrylate, -t-butyl methacrylate and the like can be used.

The blending ratio of the monomer in the "copolymer" is 10 to 20% by weight of α, β-monoethylenically unsaturated acid,
Acrylic acid ester is 20 to 60% by weight, and methacrylic acid ester is 30 to 60% by weight. In this case, the film has excellent removability with an alkaline aqueous solution. In particular,
When the amount of α, β-monoethylenically unsaturated acid is less than 7% by weight in the copolymer, it becomes difficult to remove this film with an alkaline aqueous solution.

Further, the acrylic ester and the methacrylic ester each have 1 to 18 carbon atoms as shown in the second invention.
It is desirable that the saturated aliphatic hydrocarbon monohydric alcohol ester of

As the water-soluble volatile basic compound for neutralizing the acid contained in the "copolymer", ammonia, methylamine, dimethylamine, ethylamine, diethylamine, such as morpholine has a lower boiling point and higher volatility than triethanolamine. One kind or two or more kinds of basic compounds can be used. On the other hand, neutralization with sodium hydroxide, potassium hydroxide, triethanolamine having a slow volatilization rate, or the like is not suitable because the water resistance of the protective film formed is lowered. The amount of the basic compound added may be in the vicinity of neutralization of the acidic component or more, but as shown in the third aspect of the present invention, the amount equivalent to the neutralization equivalent is preferable. If the amount is less than the neutralization equivalent of the acid component, the solubility of the copolymer in water decreases, while if it is too large, the monoethylenically unsaturated acid such as acrylic acid easily dissolves in water, resulting in copolymerization. This is because the dispersion of the product is not uniform, which is not preferable.

The "salt" is a calcium salt, a magnesium salt or a barium salt, and a calcium salt or a magnesium salt is particularly desirable. The calcium salt and the like are preferably water-soluble, but are not limited thereto. In addition, it is preferable to add a dispersant to those which are not water-soluble. The addition amount of this calcium salt or the like is 0.3 to 4.5% by weight based on the copolymer. If the added amount is less than 0.3% by weight, the ultraviolet blocking effect cannot be sufficiently obtained, and 4.
When it exceeds 5% by weight, the film-forming ability is lowered and the protective film becomes brittle, which is not preferable.

Further, "neutralize with a basic compound and add a calcium salt, a magnesium salt or a barium salt" does not mean that the order of addition is particularly restricted, and one of them may be added first, or at the same time. Good.

In the coating surface protection composition of the present invention, a plasticizer, a fusing agent, a defoaming agent, a leveling agent, a lubricant, an anti-sagging agent, a light stabilizer, and / or Alternatively, an antioxidant or the like can be added.

[Action]

In the present composition, since a copolymer composed of α, β-monoethylenically unsaturated acid, acrylic acid ester and methacrylic acid ester is used, the film performance is excellent and the film removability by an alkaline aqueous solution is also excellent. .
In addition, since the acid contained in this copolymer is neutralized with a water-soluble base compound that is easily volatilized and removed, since the base compound does not remain in the coating as it is neutralized, the characteristics of the coating are excellent and the coated surface is excellent. There is little effect on.

Further, the present composition contains a predetermined amount of calcium salt and the like. Therefore, if the present composition is applied to the coated surface,
The metal atoms are evenly distributed in the coating, which reflects the ultraviolet rays and prevents the ultraviolet rays from penetrating to the coated surface. Therefore, the deterioration of the coating film due to ultraviolet rays can be prevented. Further, similarly, since the calcium salt is contained, the acid resistance is also improved.
Further, since the atomic radius of metal atoms in these calcium salts and the like is relatively large, this effect can be exhibited even by adding a small amount of calcium salt or the like.

〔Example〕

 The present invention will be specifically described below with reference to examples.

(1) Preparation of Painted Surface Protecting Composition (a) Preparation of Copolymer Products Copolymer composition compositions A to E in this example were prepared by emulsion polymerization or solution polymerization as follows.

(A) Emulsion polymerization method In 65 parts by weight of deionized water, polyoxyethylene alkyl ether sulfate (alkyl group: C _{12 to} C as a polymerization emulsifier) is used.
₁₄ ) 0.6 part by weight, and polyoxyethylene phenyl ether (ethylene oxide addition mole number: 12 moles) 1.5 parts by weight, and ammonium persulfate 0.1 part by weight as a polymerization initiator is further added, and then at 73 ° C to 78 ° C. The temperature was raised.

Then, 34 parts by weight of the monomer mixture was added dropwise for 180 ± 10 minutes to polymerize. After completion of the polymerization, the mixture was cooled to 50 to 60 ° C., 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 for the above polymerization is shown in Table 1. Numerical values in the table indicate parts by weight. Further, the copolymer compositions A, B, D and E in the table are the monomer compositions listed in the table and have a solid content (copolymer) concentration of 35% by weight.

(B) By solution polymerization method 10 parts by weight of a 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. Then, 40 parts by weight of the monomer mixture and 40 parts by weight of ethanol were added dropwise for 300 ± 30 minutes to polymerize. 50-60 ° C after polymerization is completed After cooling, 3 parts by weight of aqueous ammonia (25% by weight) was added.

The composition of the monomer mixture used for the above polymerization is shown in Table 1. The numerical values in the table indicate parts by weight. The copolymer composition C is a monomer composition shown in the table and having a solid content (copolymer) concentration of 50% by weight.

(B) Preparation of Composition for Protecting Painted Surface Each of the copolymer compositions, calcium carbonate, aqueous ammonia and water were mixed in the proportions shown in Table 2 to give Examples 1 to 1.
Each of the compositions for protecting the painted surface of No. 8 was prepared. However,
The numerical values showing the composition in Table 2 are% by weight.

(C) Preparation of Comparative Example Product In the proportions shown in Table 3, the same copolymer composition A or C as in Example and calcium carbonate (however, Comparative Examples 1 and 6 do not contain this). Ammonia water and water were mixed to prepare the coating surface protecting compositions according to Comparative Examples 1 to 6, respectively. The numerical values showing the composition in Table 3 are% by weight.

(2) Performance test and its evaluation In order to clarify the performance of the coating surface protecting composition, the following performance tests were conducted on the compositions listed in Tables 2 and 3, and the evaluation is shown in Table 4. Show.

(A) Protection The coated test piece (black solid) has a dry film thickness of 10μ.
Samples (compositions of Examples 1 to 8 and Comparative Examples 1 to 6) were each applied so as to have m, and then ultraviolet rays (253.7 nm) were continuously irradiated for 4 weeks. Then, the change in color and luster of the coated surface when the coated surface was wiped off with 1% ammonia water was examined to evaluate the protective property, which is shown in Table 4.

The performance evaluation indications in Table 4 are as follows: ◎: no change, ○:
Slightly changed, △: changed, ×: changed, glossy,
XX: Remarkably changed and glossy, respectively.

(B) Removability A test piece (SUS301: matte finish) has a dry film thickness of 5μ
Samples (compositions of Examples 1 to 8 and Comparative Examples 1 to 6) were each applied so as to have m, and then ultraviolet rays (253.7 nm) were continuously irradiated for 4 weeks. Then, the test piece was immersed in an alkaline cleaning aqueous solution at 20 ° C., and the immersion time (second) until the coating 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,
Sodium ethylenediaminetetraacetate 0.2 wt%, polyoxyethylene alkyl ether (alkyl group: C ₁₂ ~
C ₁₄ , ethylene oxide addition mole number: 9 moles) 1% by weight and water 8
It consists of 9.8% by weight.

In addition, the performance evaluation display in Table 4 indicates ◯: removal time of 50 seconds or less, x: removal time of 200 seconds or more, respectively.

(C) Acid resistance A sample (each composition of Examples 1 to 8 and Comparative Examples 1 to 6) having a dry coating film thickness of 10 μm was placed on the same black coated plate as used for the evaluation of protection property. Apply and dry at 60 ° C for 10 minutes. Then, 0.2 to 0.3 ml of dilute sulfuric acid water adjusted to pH 3 is spot-dropped on the coated plate, and the test piece is leveled at 60 ° C.
After being left for 24 hours at 1 hour, the state of the spot surface when wiped off with 1% ammonia water was observed and evaluated.

The performance evaluation indications in Table 4 are as follows: ◎: no change, ○:
Slight change, △: Change, ×: Large discoloration of painted surface, ×
X: Indicates that the coated surface is peeled off.

(3) Effects of Examples As shown in Table 4, a copolymer having a predetermined monomer composition was used and neutralized with easily volatile ammonia water, and the amount of calcium carbonate added was 0.4 to 3.0% by weight. %, Examples 1 to 8 are remarkably excellent in ultraviolet protection and acid resistance as compared with Comparative Examples, that is, excellent in all aspects of protection, removability and acid resistance, and are very well balanced. Among these, Examples 2 and 6
When the amount of calcium carbonate added is as relatively high as 3.0% by weight, the protective property is particularly excellent.

On the other hand, in Comparative Examples 1 to 4 and 6, since the amount of calcium carbonate added was as small as 0.3% by weight or less, the removability was equivalent to that of the example product, but the protection and acid resistance were poor. On the other hand, in Comparative Example 5, since the amount of calcium carbonate added was as large as 5% by weight, the protective property was equivalent to that of the Example product, but the removability was poor.

It should be noted that the present invention is not limited to the specific embodiments described above, but can be variously modified within the scope of the present invention according to the purpose and application.

〔The invention's effect〕

By using the coating surface protection composition of the present invention, excellent acid resistance, it is possible to obtain a film having a sufficient effect of blocking ultraviolet rays, and even after being exposed to the outdoors for a long time after coating, The film can be easily removed with an alkaline aqueous solution. Therefore, by using the present composition, it is possible to maintain the quality of the vehicle outer panel and to improve the quality and workability of the product. Especially, acid rain and acid soot are presently a problem. However, the significance of the present invention is great.
Furthermore, since the composition is water-based, the risk of fire or air pollution is significantly less than when alcohol is used.

Claims (3)

[Claims] 1. A copolymer obtained by copolymerizing a monomer comprising an α, β-monoethylenically unsaturated acid, an acrylic acid ester and a methacrylic acid ester in water is neutralized with a volatile water-soluble base compound. The calcium salt, magnesium salt or barium salt is added, and the addition amount of the salt is 0.3 to 4.5% by weight with respect to the copolymer, the α, β-monoethylenically unsaturated acid, The mixing ratio of the alkacrylic acid ester and the methacrylic acid ester is 10 to 20% by weight of the α, β-monoethylenically unsaturated acid, 20 to 60% by weight of the acrylic acid ester, and 30 of the methacrylic acid ester.
A removal-type primary coating surface protection composition with an alkaline aqueous solution, characterized in that the content is -60% by weight. 2. The removable primary coating surface protection with an alkaline aqueous solution according to claim 1, wherein both the acrylic acid ester and the methacrylic acid ester are esters of C _{1 to} C ₁₈ saturated aliphatic hydrocarbon monohydric alcohols. Composition. 3. The removable primary coating surface protection composition with an alkaline aqueous solution according to claim 1, wherein the amount of the volatile basic compound used is the neutralization equivalent of the acidic component of the copolymer.