JP4973969B2 - UV shielding water-based paint with improved leveling - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an ultraviolet shielding water-based paint having improved leveling properties.
[0002]
In the present invention, the water-based paint is a paint in which about 70% or more of the solvent or dispersant contained in the paint is water.
[0003]
As water-based paints, various resins or resin compositions such as urethane-based, acrylic-based, and polyester-based ones are dissolved in a solvent containing water as a main component, or in a state of emulsion in a solvent containing water as a main component. Many dissolved or dispersed are used. Because these water-based paints do not use organic solvents, or because organic solvents are diluted with a large amount of water, they are less flammable than complete organic solvent-based paints, and the amount of organic solvents used is small. Since the degree of harm to the environment and the human body can be kept low, the amount of water-based paint used tends to increase in recent years.
[0004]
[Prior art]
Although the water-based paint has various advantages over the organic solvent-based paint as described above, the improvement thereof is strongly demanded due to the following drawbacks.
[0005]
That is, the water used in the main solvent or dispersant of the water-based paint has a larger surface tension than ordinary organic solvents, and the fluidity and spreadability of the liquid when the water-based paint is applied are inferior in so-called leveling properties. Has the disadvantages. In recent years, it is said that DIY carpenter (DIY), general consumers have purchased paints and applied paints themselves, for example, when applying water-based paints brushed on glass plates, etc. Since the leveling property of the liquid is poor, uneven coating thickness occurs. In particular, when a colored water-based paint is applied, unevenness in coating thickness is reflected as color unevenness, which causes a problem that the commercial value is greatly reduced. In addition, when applying a part of the colored water-based paint with a brush, if a part of it is overcoated, the coating liquid at the end of the overcoating is scraped off with the brush, resulting in a reduction in the amount of the coating liquid at that part and a thin coating thickness. However, with conventional water-based paints, the surrounding coating liquid spreads to a portion where the coating amount is small, i.e., leveling and the coating thickness cannot be leveled, and when it is dried as it is, the portion where the amount of coating solution is small However, there is a problem that a fatal defect occurs in that the pattern remains as a light streak pattern.
[0006]
[Problems to be solved by the invention]
Methods for solving the above-mentioned drawbacks of water-based paints, that is, methods for improving the leveling properties of water-based paints include adding and blending various organic solvents that are compatible with water, and various anionic, cationic, and nonionic interfaces. Although it has been proposed to add an activator, and also a fluorine-based or silicone-based surfactant, all of them have insufficient leveling improvement effects, and the performance of water-based paints deteriorates. There is a strong demand for a solution.
[0007]
Regarding the above, the present inventor first prepared a blue-colored aqueous emulsion containing about 2.5% of an organic solvent, pasted a sponge at the tip with a width of 3 cm, and covered it with non-woven cotton. Using a brush, the nonwoven fabric portion was impregnated with a predetermined amount of the above-mentioned aqueous emulsion, and this was applied about 10 cm from the top to the bottom on a glass plate placed on a desk. The coating was repeated so that the portion of the coating portion overlapped, and similarly, the second coating portion was overlapped so that the end portion of about 1 cm width overlapped. When dried at room temperature in this way, a blue transparent coating film can be obtained, but the coating solution at the end of the brush that has been overcoated is scraped off to reduce the amount of coating, resulting in two light-colored streak patterns. Even if it is left as it is at room temperature, the liquid leveling property of the liquid is poor, so the liquid does not flow and level out from the surroundings to the streaks. The shape pattern was admitted.
[0008]
In order to solve such problems, first, an attempt was made to add and blend various organic solvents compatible with water, which is an extension of the prior art. For example, methanol, ethanol, isopropanol, acetone, methyl ethyl ketone, ethylene glycol, diethylene glycol, propylene glycol, tetraethylene glycol, polyethylene glycol (molecular weight 200), 3-methyl-3-methoxy-1-butanol, ethylene glycol monomethyl ether, ethylene glycol mono Water such as butyl ether, tripropylene glycol, trimethylolpropane, 3-butoxy-1-butanol, 3,5-methyl-1,5-pentanediol, glycerin, cyclohexanol, cyclohexanone, γ-butyrolactone, N-methyl-2-pyrrolidone and the like A compatible organic solvent was added to the water-based paint, and the leveling improvement effect was investigated.
[0009]
Some of these organic solvents, such as ethylene glycol monobutyl ether, increase the blending amount to 20% to 30%, and in the evaluation method, there are those in which so-called vertical stripes are not recognized. Increasing the amount reduces the compatibility of resins, etc., resulting in non-uniform coating and uneven color, and the occurrence of new problems such as significantly reduced coating transparency. . In general, these organic solvents are subject to legal regulations such as the Fire Service Law and the Occupational Safety and Health Law, so it is desirable to keep the blending amount as low as possible.
[0010]
Similarly, various surfactants such as di (2-ethylhexyl) sulfosuccinic acid, sodium oleate, sodium dodecylbenzenesulfonate, fluorine-based surfactants such as Unidyne DS-403 (instead of an organic solvent compatible with water) are used. Leveling properties could not be improved even when Daikin Industries, Ltd.) or a silicone surfactant such as SH-29PA (Toray Silicone Co., Ltd.) was blended.
[0011]
[Means for Solving the Problems]
The first invention of the present application is characterized in that leveling properties are improved by blending ethylene carbonate with an ultraviolet shielding water-based paint .
[0012]
The second invention of the present application is characterized in that leveling properties are improved by blending ethylene carbonate and at least one of organic solvents compatible with water into an ultraviolet shielding water-based paint .
[0013]
The above-mentioned ethylene carbonate is a white crystal having a solidification point of about 36 ° C, which is solid at room temperature, is stable and non-toxic, is not applicable to the Fire Service Act and the Industrial Safety and Health Act, and has low flammability of water-based paints. It is an extremely excellent chemical substance that meets the characteristics of the environment and human body.
[0014]
Ethylene carbonate is a substance that mixes well with water and many organic solvents and has an excellent dissolving power for many polymer substances. Therefore, it is added to emulsions and solutions of water-based paints. However, it is presumed that an excellent leveling improvement effect was exhibited because the emulsion was uniformly dissolved in the entire coating material without destroying the emulsion or precipitating the resin component from the solution. Moreover, since the solubility with respect to a high molecular material is excellent, the coating film obtained by apply | coating and drying is maintaining the same outstanding transparency as an ethylene carbonate additive-free type | system | group.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
As an organic solvent compatible with water blended with ethylene carbonate, highly flammable solvents such as methanol, ethanol, isopropanol, acetone, and methyl ethyl ketone are not desirable, and relatively high boiling point solvents such as ethylene glycol and propylene glycol. , Tetraethylene glycol, isoprene glycol, 3-methyl-3-methoxy-1-butanol, ethylene glycol monomethyl ether, ethylene glycol monobutyl ether, tripropylene glycol, trimethylolpropane, 3-butoxy-1-butanol, 3,5-methyl-1, Examples of preferable organic solvents include 5-pentanediol, glycerin, γ-butyrolactone, N-methyl-2-pyrrolidone and the like. In selecting these organic solvents, it is necessary to consider the type of resin used in the aqueous paint and the composition of the aqueous paint. By blending these organic solvents, water-based paint emulsions should not be broken, or those that can separate blended components such as resins from water-based paints should not be used.
[0016]
Regarding the blending amount of ethylene carbonate in the present invention, the type and composition of the water-based paint, that is, the type of resin and its blending amount, the blending amount of water, the kind and amount of the organic solvent that may be blended in a small amount, It is necessary to optimize the blending amount of ethylene carbonate depending on the type and amount of other added materials, but usually 100 parts by weight of water-based paint after blending ethylene carbonate and water-compatible organic solvent. About 0.5 to 15 parts by weight of ethylene carbonate is blended, but it is desirable to blend so as to be about 1 to 10 parts by weight in the sense of suppressing the blending amount as much as possible.
[0017]
In addition, the ratio of the total organic solvent and ethylene carbonate in the water-based paint needs to be optimized depending on the type and composition of the water-based paint as described above, but usually the weight ratio of the total organic solvent amount to the ethylene carbonate amount is It is desirable to suppress the amount to 20 or less, and it is particularly desirable to determine the ratio of the total organic solvent amount to the ethylene carbonate amount so as to reduce the total organic solvent amount as much as possible.
[0018]
The blending method of ethylene carbonate is not particularly limited, and it is possible to add solid ethylene carbonate directly to the aqueous paint and stir until a uniform paint system is obtained. A water-based paint having a resin (high solid content) concentration is prepared, and an aqueous solution in which a predetermined amount of ethylene carbonate is dissolved or a solution in which ethylene carbonate is dissolved in a mixed solution of water and an organic solvent is added and stirred. It is desirable to make it an aqueous paint emulsion or solution.
[0019]
The water-based paint with improved leveling properties provided by the present invention can be used in various applications. In recent years, DIY has been widely used by general consumers to purchase paints having specific functions and apply them to various objects themselves. In this case, it is a matter of course that a water-based paint that is friendly to the environment and the human body is desirable. However, as described above, the known water-based paint has poor leveling properties (fluidity and spreadability) of the applied liquid, and coating unevenness. In particular, in the field of DIY, organic solvent-based paints that are still harmful are still the mainstream because colored unevenness causes uneven application of color and color unevenness.
[0020]
The paint with various functions added to the water-based paint base with improved leveling property according to the present invention, for example, an ultraviolet shielding paint, is used for a window glass of a vehicle such as an automobile, a window glass of a general household or a building, and a cathode ray tube of a television. It can be easily applied to the surface and other film and plastic surfaces with your own hands. In addition, colored paints and the like prepared for the purpose of shielding or reducing light having a wavelength harmful to the eyes and human body other than ultraviolet rays can be similarly applied to various objects.
[0021]
【Example】
EXAMPLES Hereinafter, although this invention is demonstrated in more detail based on an Example, this invention is not limited by these Examples. In addition, Example 1, Example 2, Example 3, and Example 7 show the conventional example for leveling property evaluation of a coating liquid, and the external appearance evaluation of a coating film compared with the Example of this invention. It is.
[0022]
A colored water-based paint in which 1 part of a blue pigment was blended with 100 parts of the water-based paint to be tested was prepared in order to more clearly evaluate the leveling property evaluation method of the coating liquid and the appearance evaluation level of the coating film.
[0023]
Next, a sponge was applied so that the tip of a plastic plate having a width of 3 cm, a thickness of 3 mm, and a length of 10 cm was covered, and a non-woven cotton was applied thereon.
[0024]
A non-woven cotton portion of the brush is impregnated with a predetermined amount of a water-based paint to be tested, and this is placed on a transparent glass plate (washed with water, then washed with methanol, and dried) placed on a desk, from top to bottom. Apply about 10 cm (the first application), and then repeat the application from the top to the bottom so that the part about 1 cm overlaps the left end of the first application (the second application). Overpainting (third coating) was performed from top to bottom so that a portion of about 1 cm from the left end of the second coating portion overlapped. When overcoating is performed in this manner, the coating liquid at the right end portion of the brush is scraped off, resulting in a decrease in the amount of liquid and generation of vertical stripes with a lighter color. That is, two vertical stripes are generated by applying three times. This is left to dry at room temperature, but when the leveling property of the coating solution is poor, it becomes a coating film with vertical stripes remaining, and when the leveling property is good, the vertical stripes are exposed from the surroundings. The coating solution flows, the streaks disappear, and a uniform coating film is obtained. By observing such a phenomenon, the leveling property of the coating solution was evaluated.
[0025]
At the same time, the color unevenness and transparency of the coating film were observed and evaluated with the naked eye.
[0026]
(Example 1) Production and evaluation of paint A According to a usual method, 33.0 parts of an aqueous urethane resin (resin solid concentration of about 32%), 0.2 part of an emulsifier, 10.0 parts of water, an ultraviolet absorber 4. A base solution of an aqueous urethane-based ultraviolet shielding coating comprising 6 parts and 2.2 parts of ethylene glycol monobutyl ether (hereinafter abbreviated as butyl cellosolve) was prepared. And in order to improve workability | operativity as a coating material, 50 parts of water was added and diluted to 50 parts of the said original liquid, and the water-based urethane type ultraviolet-ray shielding coating material of about 15% of total solid concentration was produced. The amount of butyl cellosolve in the total water-based paint of this system is about 2.2%.
[0027]
When the leveling property of this paint was evaluated, two vertical streaks remained clearly in the dried coating film, and the leveling property was poor. However, the coating film showed excellent transparency.
[0028]
(Example 2) Preparation and evaluation of paint B After preparing the base liquid of the water-based ultraviolet shielding paint in the same manner as paint A, instead of diluting paint A with 50 parts of water, 7.8 parts of butyl cellosolve and 42.2 of water Diluted with a mixture of parts. The amount of butyl cellosolve in the total water-based paint of this system is 10%.
[0029]
The leveling property of the paint B was still insufficient, and two vertical stripes remained, and it was recognized that the transparency of the coating film was slightly lowered.
[0030]
(Example 3) Production and evaluation of paint C The same original solution as paint A was diluted with a mixed solution composed of 17.8 parts of butyl cellosolve and 32.2 parts of water. The amount of butyl cellosolve in the total water-based paint of this system is about 20%. Although the leveling property of the paint was good, it was recognized that the color unevenness was strong, the coating film was cloudy, and the transparency was lowered.
[0031]
(Example 4) Preparation and evaluation of paint D The same original solution as paint A was diluted with a mixed solution consisting of 8 parts of ethylene carbonate and 42 parts of water. The amount of butyl cellosolve in this all-water paint is 2.2% and the amount of ethylene carbonate is 8%.
[0032]
The leveling property of this paint was relatively good, and two vertical stripes were hardly recognized. The transparency of the coating film was also good.
[0033]
(Example 5) Preparation and evaluation of paint E The same stock solution as paint A was diluted with a mixed solution consisting of 5 parts of ethylene carbonate, 7.8 parts of butyl cellosolve and 36.2 parts of water. The amount of butyl cellosolve in this all-water paint is 10% and the amount of ethylene carbonate is 5%.
[0034]
Although the leveling property of this paint was better than that of Example 4, it was recognized that the transparency of the coating film was lowered.
[0035]
(Example 6) Preparation and evaluation of paint F For the purpose of improving transparency of 4 parts of ethylene carbonate, 4.8 parts of butyl cellosolve and a coating film in the same original solution as paint A, it has excellent dissolving power for urethane resin. The mixture was diluted with a mixed solution consisting of 3 parts of N-methyl-2-pyrrolidone and 39.2 parts of water. The amount of ethylene carbonate in this all-water paint is 4%, the amount of butyl cellosolve is 7%, and the amount of N-methyl-2-pyrrolidone is 3%. The leveling property of this paint was better than that of Example 4, and the coating film maintained excellent transparency.
[0036]
(Example 7) Production and evaluation of paint G According to a usual method, 30.0 parts of an aqueous acrylic resin (resin solid content concentration of about 38%), 0.2 part of emulsifier, 12.0 parts of water, UV absorber 5. A base solution of an aqueous acrylic ultraviolet shielding coating composed of 3 parts and 2.5 parts of butyl cellosolve was prepared. 50 parts of this original solution was diluted with 50 parts of water to prepare an aqueous acrylic ultraviolet shielding paint having a total solid concentration of about 17%. The amount of butyl cellosolve in the total water-based paint of this system is 2.5%.
[0037]
Although this paint exhibited excellent transparency, the leveling property was poor as in Example 1.
[0038]
(Example 8) Preparation and evaluation of coating material H The original solution of coating material G was diluted with a mixed solution consisting of 7 parts of ethylene carbonate, 5.5 parts of 3-butoxy-1-butanol, and 37.5 parts of water. The amount of ethylene carbonate in this all-water paint is 7%, the amount of butyl cellosolve is 2.5%, and the amount of 3-butoxy-1-butanol is 5.5%. The leveling property of this paint was good, and the coating film showed excellent transparency.
[0039]
【Effect of the invention】
Water-based paints have low flammability and are attracting attention as environmentally friendly and human-friendly paints. However, water has a very large surface tension compared to commonly used organic solvents, so it is applied to glass plates. In this case, the fluidity and spreadability, that is, leveling properties are poor, and there is a great disadvantage that uneven coating tends to occur. As a method for improving such leveling properties, a method of reducing the surface tension of water by adding an organic solvent compatible with water has been conventionally considered. In this method, a large amount of organic solvent is added. As a result, there arises a new problem that the advantages of water-based paints such as low flammability, environment and human body are impaired.
[0040]
In contrast, ethylene carbonate is a white crystalline solid at room temperature, is odorless and harmless, and does not fall under the legal regulations of the Fire Services Act or the Industrial Safety and Health Act. It is truly flammable and friendly to the environment and the human body. It can be said that it is optimal as a compound to be blended in water-based paints for sale.
[0041]
In addition, ethylene carbonate is compatible with water and various organic solvents, exhibits excellent dissolving power for various polymer substances, and acts as a solvent. The coating is stable and forms a uniform coating without destroying the emulsion or causing phase separation of the resin in the aqueous coating.
[0042]
Thus, this invention improves the leveling property of the water-based paint produced by mix | blending ethylene carbonate, and provides the water-based paint suitable for DIY (DIY). In addition, it maintains the characteristics of a low flammability and environmentally friendly water-based paint. The invention of claim 2 has an effect of providing a coating film having excellent permeability in addition to the improvement of leveling property.

Claims (4)

An ultraviolet shielding water-based paint characterized in that leveling properties are improved by blending ethylene carbonate into the ultraviolet shielding water-based paint. An ultraviolet shielding water-based paint having improved leveling properties by blending at least one of ethylene carbonate and an organic solvent compatible with water into the ultraviolet shielding water-based paint. 3. The ultraviolet shielding water-based paint with improved leveling properties according to claim 1 or 2, wherein the ultraviolet shielding water-based paint is based on a urethane resin. 3. The ultraviolet shielding water-based paint with improved leveling property according to claim 1, wherein the ultraviolet shielding water-based paint is based on an acrylic resin.