JP-7856825-B1 - Water-based coating agent

Abstract

[Problem] To provide polyurethane urea particles that, when used as a component of an aqueous coating agent, easily form a matte-finish film with good abrasion resistance, flexibility at low temperatures, heat resistance, and soft feel. [Solution] The polyurethane urea particles are reaction products of a reactive component containing a polyol, a polyamine, and a polyisocyanate. The polyisocyanate contains a polyisocyanate crosslinking agent with more than two functional groups. The polyurethane urea particles have a crosslinking density of 0.30 mol/kg or more and 0.80 mol/kg or less derived from the polyfunctional component in the reactive component with more than two functional groups. The urea group content in the polyurethane urea particles is 0.50 mol/kg or more and 2.00 mol/kg or less. Furthermore, the volume-average particle diameter of the polyurethane urea particles is 1 μm or more and 30 μm or less. [Selection Diagram] None

Inventors

• 武藤 多昭

Assignees

• 大日精化工業株式会社

Dates

Publication Date

20260511

Application Date

20250613

Claims (5)

1. An aqueous coating agent containing polyurethane urea particles, which are reaction products of reactive components including polyols, polyamines, and polyisocyanates, The polyisocyanate comprises a polyisocyanate crosslinking agent having more than two functional groups. The crosslinking density derived from polyfunctional components in the reactive component having more than two functional groups is 0.30 mol/kg or more and 0.80 mol/kg or less. The urea group content in the polyurethane urea particles is 0.50 mol/kg or more and 2.00 mol/kg or less. The volume-average particle diameter of the polyurethane urea particles is 1 μm or more and 30 μm or less. A water-based coating agent for synthetic imitation leather .
2. The aqueous coating agent according to claim 1, wherein the polyol comprises at least one polymer polyol selected from the group consisting of polyether polyols and polycarbonate polyols.
3. The aqueous coating agent according to claim 2, wherein the content of the polymer polyol relative to the total mass of the reactive component is 45% by mass or more and 80% by mass or less.
4. The aqueous coating agent according to claim 1, wherein the polyisocyanate comprises at least one aliphatic polyisocyanate selected from the group consisting of chain-type aliphatic polyisocyanates and cyclic aliphatic polyisocyanates.
5. The aqueous coating agent according to claim 1, wherein the 10% compressive strength of the polyurethane urea particles at 25°C is 0.1 MPa or more and 1.4 MPa or less.

Description

This invention relates to polyurethane urea particles, aqueous dispersions of polyurethane urea particles, and aqueous coating agents. Traditionally, various surfaces have been coated with paint for purposes such as protection and aesthetic enhancement. For example, matte paints are sometimes used on surfaces of objects that people see and touch, such as transportation equipment, buildings, electrical appliances, furniture, toys, and general merchandise, to reduce gloss and create a subdued, understated appearance. Furthermore, in recent years, due to environmental concerns and safety considerations, there has been a shift towards water-based paints, and the demand for water-based matte paints has increased. On the other hand, polyurethane resins, including polyurethane resins, polyurea resins, and polyurethane-urea resins, are widely used in coatings such as paints and inks. Polyurethane resins are not only used as binder resins in coatings; particulate polyurethane resins, also known as polyurethane beads, are sometimes incorporated into coatings as fillers to achieve the aforementioned matte finish. For example, Patent Document 1 proposes a matte coating using a resin composition containing a polyurethane aqueous dispersion with an average particle size of 1.5 to 4.0 μm and a polyurethane aqueous dispersion with an average particle size of 0.01 to 1.0 μm. Patent Document 2 proposes a matte coating containing a polyurethane urea aqueous dispersion, which is a reaction product of a high-molecular-weight polyol, a compound having active hydrogen and hydrophilic groups, a dihydric alcohol, a polyisocyanate, and a predetermined polyamine. Japanese Patent Publication No. 2007-308587Japanese Patent Publication No. 2019-011408 This is an SEM image of the polyurethane urea particles used in Example 1. The following describes embodiments of the present invention, but the present invention is not limited to these embodiments. In this disclosure, "functional group" in the description of polyurethane urea particles refers to a functional group that contributes to urethane bonding or urea bonding. Specific examples of functional groups include hydroxyl groups, amino groups, and isocyanate groups. For polyols, the functional group is a hydroxyl group; for polyamines, it is an amino group; and for polyisocyanates, it is an isocyanate group. Furthermore, in this disclosure, "number of functional groups" refers to the number of functional groups within one molecule. <Polyurethane urea particles> Polyurethane urea particles of one embodiment of the present invention (hereinafter sometimes simply referred to as "polyurethane urea particles") are reaction products of a reactive component containing a polyol, a polyamine, and a polyisocyanate. The polyisocyanate used in the reactive component contains a polyisocyanate crosslinking agent having more than two functional groups. In addition to the polyisocyanate crosslinking agent having more than two functional groups, the reactive component may also contain other polyfunctional components having more than two functional groups. The polyurethane urea particles have a crosslinking density derived from the polyfunctional component having more than two functional groups in the reactive component that is 0.30 mol/kg or more and 0.80 mol/kg or less. Furthermore, the urea group content in the polyurethane urea particles is 0.50 mol/kg or more and 2.00 mol/kg or less. In addition, the volume-average particle diameter of the polyurethane urea particles is 1 μm or more and 30 μm or less. By using polyurethane urea particles having the above configuration as a component of an aqueous coating agent (hereinafter sometimes simply referred to as "coating agent"), it is possible to form a film with a matte appearance. Furthermore, this film tends to exhibit good abrasion resistance, flexibility at low temperatures (e.g., -10°C), heat resistance sufficient to maintain its matte appearance even after heating to, for example, around 200°C, and a soft feel that creates a luxurious impression. Therefore, the above polyurethane urea particles are suitable as a component of coating agents such as paints, inks, and surface treatment agents. The reactive components forming the polyurethane urea particles will be described below, followed by a description of the characteristics of the polyurethane urea particles, such as the crosslinking density, urea group content, and volume-average particle diameter. (Polyol) Polyols are compounds that have two or more hydroxyl groups in a single molecule. Polyols are compounds that, through reaction with polyisocyanates, produce urethane bonds in polyurethane urea particles. Examples of polyols include high molecular weight polyols and low molecular weight polyols. In this disclosure, high molecular weight polyols are polyols with a higher molecular weight than low molecular weight polyols. Low molecular weight polyols are polyols with a lower molecular weight than