CN-122029244-A - Aqueous coating composition

Abstract

An aqueous coating composition comprising a coating film-forming resin, an aluminum powder having a silicon-containing coating film, and a solvent comprising water, wherein the aluminum powder having a silicon-containing coating film has δpa as an apparent dipole-to-dipole force, the δpa being 10.65 or more, and the dipole-to-dipole force of the solvent being δpa+1.00 or less.

Inventors

• UEMURA YOSHIYA
• Kumazaki Eisaku
• SAKAKIBARA FUMIYA
• Blue or green wooden good son
• OKAZAKI YASUHIRO
• SUZUKI SATOSHI
• TANIGAWA SHINICHI

Assignees

• 日涂汽车涂料有限公司

Dates

Publication Date

20260512

Application Date

20240723

Priority Date

20231018

Claims (4)

1. 1. An aqueous coating composition comprising: a coating film forming resin; Aluminum powder with silicon-containing coating film, and A solvent comprising water and water, The aluminum powder having a silicon-containing coating film has δpa as apparent dipole-to-dipole force obtained by the following method, The delta pa is more than 10.65, The dipolar interforce of the solvent is equal to or less than δpa+1.00, The method for obtaining apparent dipole-dipole force of aluminum powder comprises the following steps: The method comprises the steps of adding 0.0005g of the aluminum powder with a silicon-containing coating to a reference solvent obtained by mixing pure water and methanol in a predetermined ratio, measuring the time taken until all the aluminum powder with a silicon-containing coating is precipitated, and taking the maximum force among dipole-to-dipole forces of the reference solvent when the time is 60 seconds or less as apparent dipole-to-dipole force (δpa) of the aluminum powder with a silicon-containing coating.
2. 2. The aqueous coating composition according to claim 1, wherein the dipolar interaction force of the solvent is 9.70 or more and 15.3 or less.
3. 3. The aqueous coating composition according to claim 1 or 2, wherein the mass ratio of the aluminum powder having a silicon-containing coating film is 0.1 mass% or more and 50 mass% or less with respect to the mass of the solid content of the resin of the aqueous coating composition.
4. 4. The aqueous coating composition according to any one of claims 1 to 3, wherein the coating film-forming resin comprises an aqueous acrylic resin.

Description

Aqueous coating composition Technical Field The present invention relates to aqueous coating compositions. Background In recent years, in order to protect the environment, it has been demanded to reduce Volatile Organic Compounds (VOCs) emitted from factories and the like. As one of the methods of reducing VOC emissions, aqueous coating compositions are proposed. Since aluminum powder, which is commonly used as a brightening pigment, reacts with water, it is generally compounded into an aqueous coating composition in a surface-treated state. In contrast, patent documents 1 and 2 disclose that aluminum powder covered with silica is compounded into an aqueous paint. Prior art literature Patent literature Patent document 1 Japanese patent application laid-open No. 2015-187246 Patent document 2 Japanese patent laid-open publication 2016-188285 Non-patent literature Non-patent document 1: the "measurement affinity-solubility parameter- (Japanese: lever and Messaging-solubility in one's thumb-)", color materials society, general society act, color materials society, 77 (4), 188-192 (2004). Disclosure of Invention Problems to be solved by the invention It is difficult to stably disperse the aluminum powder in water. The purpose of the present invention is to provide an aqueous coating composition that contains aluminum powder and has excellent dispersion stability. Means for solving the problems In order to solve the above problems, the present invention provides the following means. [1] An aqueous coating composition comprising: a coating film forming resin; Aluminum powder with silicon-containing coating film, and A solvent comprising water and water, The aforementioned aluminum powder having a silicon-containing coating film has δpa as apparent dipole-to-dipole force obtained by the following method, The δpa is 10.65 or more, The dipolar force of the solvent is equal to or less than δpa+1.00. (Method for obtaining apparent dipole-dipole force of aluminum powder) The aluminum powder having a silicon-containing film was poured into a reference solvent obtained by mixing pure water and methanol at a predetermined ratio by 0.0005g, and the time taken until all the aluminum powder having a silicon-containing film was precipitated was measured. The maximum force among the dipole-to-dipole forces of the reference solvent when the time is 60 seconds or less is taken as the apparent dipole-to-dipole force (δpa) of the aluminum powder having the silicon-containing coating film. [2] The aqueous coating composition according to the above [1], wherein the dipolar interaction force of the solvent is 9.70 or more and 15.3 or less. [3] The aqueous coating composition according to the above [1] or [2], wherein the mass ratio of the aluminum powder having a silicon-containing coating film is 0.1 mass% or more and 50 mass% or less with respect to the mass of the solid content of the resin of the aqueous coating composition. [4] The aqueous coating composition according to any one of the above [1] to [3], wherein the coating film-forming resin comprises an aqueous acrylic resin. Effects of the invention According to the present invention, there is provided an aqueous coating composition containing aluminum powder and having excellent dispersion stability. Detailed Description In order to impart water resistance, aluminum powder compounded in an aqueous coating composition is generally surface-treated. The surface treatment of the aluminum powder may use, for example, an inorganic phosphorus compound, a molybdenum compound, a silicon compound, or an organic resin. Among them, aluminum powder treated with a silicon compound is high in water dispersibility. However, even in the case of an aluminum powder having a silicon-containing coating film (hereinafter referred to as a silica-coated aluminum powder), dispersion stability is not good. The wettability of the pigment with respect to the solvent affects the dispersion stability of the pigment. By wetting the pigments with a solvent, the aggregation force of the pigments with each other is reduced, and as a result, dispersion can occur. As the evaluation of wettability, a method using a solubility parameter (SP value) is widely known. The SP value is calculated from three forces of van der waals force (δd), dipole-dipole force (δp), and hydrogen bond force (δh). The SP value can be expressed in a three-dimensional coordinate space of (δd, δp, δh) with the respective forces as axes. The SP value is an index of solubility of a two-component solvent, and for example, as in non-patent document 1, it is also proposed to use the SP value as an index of pigment dispersibility. In non-patent document 1, a pigment is suspended in a predetermined amount of water in advance, and a water-miscible organic solvent such as acetone or methanol is added dropwise so as not to directly contact the pigment. The SP value of the mixed solution of water and organic solvent at the start of pigment sedimenta