JP-7855378-B2 - Acrylic urethane composite resin, aqueous paint composition, and method for forming a multi-layer coating film

Inventors

• 渡辺 和也

Assignees

• 関西ペイント株式会社

Dates

Publication Date

20260508

Application Date

20220323

Claims (7)

1. (A) A urethane resin portion obtained from a constituent component comprising (a1) a polyisocyanate component, and (a2) (a2-1) a compound having two or more hydroxyl groups and one or more polymerizable unsaturated groups and (a2-2) a polyol component containing polytetramethylene ether glycol, (B) comprising an acrylic resin portion obtained from a component comprising (b1) a compound having one polymerizable unsaturated group and no hydroxyl group or having one hydroxyl group, and (b2) a compound having two or more polymerizable unsaturated groups and no hydroxyl group or having one hydroxyl group, The core-shell structure consists of a shell made of the urethane resin portion (A) and a core made of the acrylic resin portion (B). Aqueous dispersion of acrylic urethane composite resin.
2. The aqueous dispersion of the acrylic urethane composite resin according to claim 1, wherein the polyisocyanate component (a1) comprises an alicyclic polyisocyanate (a1-1).
3. An aqueous dispersion of an acrylic urethane composite resin according to claim 1 or 2, wherein the content of the compound (b2) having two or more polymerizable unsaturated groups and having neither a hydroxyl group nor one hydroxyl group is in the range of 0.5 to 50% by mass, based on the total solid content of the acrylic resin portion (B).
4. An aqueous coating composition containing an aqueous dispersion of an acrylic urethane composite resin according to any one of claims 1 to 3 .
5. The aqueous paint composition according to claim 4 , further comprising at least one resin selected from acrylic resin (C) and polyester resin (D).
6. The aqueous paint composition according to claim 4 or 5 , further containing a curing agent (E).
7. Step (1): A step of applying the aqueous paint composition described in any one of claims 4 to 6 onto the object to be coated to form a base coat film. Step (2): A step of applying a clear coat coating composition onto the base coat coating formed in step (1) to form a clear coat coating, and, A method for forming a multilayer coating film, comprising step (3): a step of simultaneously heating and curing the base coat coating film formed in step (1) and the clear coat coating film formed in step (2).

Description

This invention relates to an acrylic urethane composite resin, an aqueous coating composition, and a method for forming a multi-layer coating film. One of the performance requirements for multi-layer automotive coatings is chipping resistance (chipping: damage to the coating caused by small stones or other debris flying up from the road and impacting the coating). For example, efforts have been made to improve chipping resistance by softening the coating to absorb the impact energy of such debris. Due to its excellent physical properties, urethane resin has been widely used as a resin in paint applications to improve coating performance, such as chipping resistance. Furthermore, acrylic-urethane composite resins are also used in the paint industry and other fields for purposes such as synergistic effects between acrylic resin and urethane resin, improved compatibility when applied to acrylic resin-based paint compositions, and cost reduction of urethane resin. However, attempting to improve chipping resistance by softening the acrylic-urethane composite resin can lead to storage stability problems, such as increased viscosity or sedimentation during storage of the paint composition. Patent Document 1 describes an aqueous dispersion of acrylic-polyurethane resin obtained by polymerizing a polyurethane resin (A) containing polyols (a1) consisting of 86 to 96% by weight of polycarbonate diol and 14 to 4 % by weight of an anionic functional group-containing polyol, polyisocyanates (a2), and an acrylic compound (a3) having an active hydrogen-containing group as reaction components, and a polymerization component (B) containing alkyl (meth ) acrylates (b1) represented by general formula (1): CH₂= CR₁COOR₂ (wherein R₁ represents a hydrogen atom or a methyl group, and R₂ represents an alkyl group having 1 to 18 carbon atoms) in the presence of water, which exhibits excellent storage stability. Furthermore, Patent Document 2 describes a step of (i) first charging an aqueous dispersion of at least one polyurethane, and then (ii) polymerizing a mixture of olefinic unsaturated monomers in the presence of the polyurethane from (i), wherein (a) a water-soluble initiator is used, (b) the olefinic unsaturated monomers are metered and supplied so as not to exceed a concentration of 6.0% by mass in the reaction solution relative to the total amount of olefinic unsaturated monomers used for polymerization during the entire reaction time, and (c) the mixture of olefinic unsaturated monomers comprises at least one copolymer (CP), and 20 mg A water-based paint composition comprising a linear hydroxy-functional reaction product (R) having an acid value of less than KOH/g, wherein the production of the linear hydroxy-functional reaction product (R) involves the use of at least one compound (v) having two functional groups (v.a) and an aliphatic or aromatic aliphatic hydrocarbyl group (v.b) having 12 to 70 carbon atoms positioned between the functional groups, is described as having excellent resistance to scratches caused by stones. Japanese Patent Publication No. 2008-189696JP 2017-509725 The present invention will be described in detail below, but these are merely examples of preferred embodiments, and the present invention is not limited to these descriptions. [Acrylic urethane composite resin (AB)] The acrylic urethane composite resin (AB) of the present invention comprises a urethane resin portion (A) obtained from constituent components including a polyisocyanate component (a1), a polyol component (a2) containing a compound (a2-1) having two or more hydroxyl groups and one or more polymerizable unsaturated groups and polytetramethylene ether glycol (a2-2), This is an acrylic urethane composite resin comprising an acrylic resin portion (B) obtained from a component comprising a compound (b1) having one polymerizable unsaturated group and no hydroxyl group or having one hydroxyl group, and a compound (b2) having two or more polymerizable unsaturated groups and no hydroxyl group or having one hydroxyl group. Acrylic urethane composite resin (AB) can be manufactured using conventionally known methods for producing acrylic urethane composite resins. However, from the viewpoint of manufacturing stability and other factors, it is preferable to manufacture it using the following method (consisting of the manufacturing steps 1 to 3 below). Manufacturing Process 1. First, the urethane resin portion (A) is synthesized in the presence of a compound (b1) having one polymerizable unsaturated group and no hydroxyl group or having one hydroxyl group, and a compound (b2) having two or more polymerizable unsaturated groups and no hydroxyl group or having one hydroxyl group, which are components of the acrylic resin portion (B). Manufacturing process 2. Next, deionized water is added and emulsified to obtain an aqueous dispersion. If necessary, further chain extension reactions and solvent removal are performed. Manufacturing process 3. Next,