Search

KR-102964722-B1 - Non-aqueous crosslinkable composition with improved appearance

KR102964722B1KR 102964722 B1KR102964722 B1KR 102964722B1KR-102964722-B1

Abstract

The present invention relates to a1) a polyol having a weight average molecular weight Mw of 1,000 to 4,000 daltons, a number average molecular weight Mn of 600 to 2,500 daltons, an OH value of 80 to 300 mg KOH/1 g resin, and a glass transition temperature Tg of -10 to 90 °C, and a2) a polyol component comprising 0.1 to 10 weight% of a polyurea product as a rheological agent, and the use thereof in a crosslinkable composition particularly suitable for clear coat applications.

Inventors

  • 더 볼프 엘빈
  • 후데허뷔러 마리뉘스

Assignees

  • 알넥스 네덜란드 비. 브이.

Dates

Publication Date
20260513
Application Date
20191105
Priority Date
20181106

Claims (19)

  1. Polyol components including the following: ● Polyol a1) 35 to 95 wt%, wherein the weight-average molecular weight Mw is 1,000 to 4,000 daltons, the number-average molecular weight Mn is 600 to 2,500 daltons, the hydroxyl value is 80 to 300 mg KOH/1 g resin, the glass transition temperature Tg is -10 to 90 °C, and Tg is measured using a Mettler DSC 822E calorimeter according to DEN EN ISO 16805 and ISO 11357, and ● Polyurea product a2) 0.1 to 10 weight% as a rheological agent.
  2. In claim 1, the polyol a1) is a polyol component having an Mw of less than 3,000 daltons and a glass transition temperature Tg greater than -5°C.
  3. In claim 1, the polyol a1) is a polyol component selected from polyester polyols, (meth)acrylic polyols and mixtures or hybrids thereof.
  4. A polyol component according to claim 1, wherein polyol a1) is a (meth)acrylic polyol having a weight average molecular weight Mw of 1,500 to 4,000 daltons and a number average molecular weight Mn of 900 to 2,500 daltons.
  5. In claim 1, the polyol component, wherein polyol a1) is a (meth)acrylic polyol obtained from the following: - 5 to 50 weight% of styrene or substituted styrene monomer, - 10 to 50 weight% of hydroxy-functional (meth)acrylic monomer - 10 to 70 weight% of linear or branched alkyl (meth)acrylate monomer having an alkyl group comprising 1 to 6 carbon atoms - 0 to 20 weight% of linear or branched alkyl (meth)acrylate monomer having an alkyl group comprising 7 to 20 carbon atoms - 0 to 5 weight percent (meth)acrylic acid.
  6. A polyol component according to claim 1, wherein polyol a1) is a polyester polyol having a weight average molecular weight Mw of 1,000 to 3,000 daltons and a number average molecular weight Mn of less than 1,500 daltons.
  7. In claim 1, the polyol component, wherein polyol a1) is a polyester polyol obtained from the following polymerization: - 5 to 58 weight% of one or more at least difunctional carboxylic acids, their C1-C4 alkyl esters and/or their anhydrides, - 42 to 95 weight% of at least a difunctional hydroxy compound, ○ 0 to 40 weight% of a difunctional hydroxy compound, ○ 0 to 49 weight% of a trifunctional hydroxy compound, and ○ At least a difunctional hydroxyl compound comprising 0 to 10 weight% of a tetrafunctional hydroxyl compound, and - 0 to 50 weight% of a linear or branched monofunctional carboxylic acid and/or hydroxy compound comprising 4 to 20 carbon atoms.
  8. In claim 1, the polyol component, wherein the polyurea product a2) is a urea product formed from the reaction of a polyisocyanate or its isocyanurate, biuret, or urethdione derivative with one or more mono-amines.
  9. A polyol component wherein the polyisocyanate is selected from the group consisting of hexamethylene-1,6-diisocyanate (HMDI), its isocyanurate trimer or its biuret, trans-cyclohexylene-1,4-diisocyanate, para- and meta-xylene diisocyanates, and toluene diisocyanate, and/or the mono-amine is a primary amine selected from n-aliphatic amines, or n-alkylamines, or hexylamine; cyclohexylamine; benzylamine; 3-methoxypropylamine; S-alpha-methylbenzylamine and 2-phenethylamine, and mixtures thereof.
  10. In claim 1, the polyurea product a2) is a polyol component prepared in the presence of polyol a1).
  11. A polyol component according to claim 1, wherein the amount of polyol a1) among the polyol components is 50 to 90 weight%, and the polyol R is different from polyol a1) and is less than 40 weight% with respect to the total weight of polyol a1), polyol R), and polyurea product a2).
  12. A crosslinkable composition comprising the following: a) one or more polyol components according to any one of claims 1 to 11, b) Optionally, one or more polyols b) which may be identical to or different from polyol a1), said polyol b) having two or more free -OH groups c) a crosslinking agent c) capable of reacting with polyol a1) and/or b), and d) Optionally, a catalyst for catalyzing the reaction between the -OH group of the polyol a1) and/or b) and the crosslinking agent c).
  13. A crosslinkable composition according to claim 12, wherein polyol b) is present and has an Mw of 700 to 10,000 daltons and a glass transition temperature Tg of -80 to 90°C.
  14. In claim 12, the polyol b) is a crosslinkable composition selected from polyester polyols and (meth)acrylic polyols, polyacrylate polyester polyol hybrids and mixtures thereof.
  15. A crosslinkable composition according to claim 12, wherein the crosslinking agent c) is selected from an amino crosslinking agent resin, an isocyanate or a blocked isocyanate or a mixture of an amino crosslinking agent resin and a (blocked) isocyanate.
  16. A crosslinkable composition according to claim 12, wherein the solid content is 50 weight% or more, or exceeds 55 weight%, at the applied viscosity.
  17. The crosslinkable composition of claim 12, comprising the following based on the total amount of polyol a1), polyurea product a2), polyol b), crosslinking agent c), and, if present, catalyst d): ● Polyurea product a2) 0.1 to 10, or 0.2 to 3, or 0.3 to 2 weight%, ● Polyol a1) + Polyol b) 10 to 89 weight%, ● Crosslinking agent c) 10 to 89 weight%, ● Optionally, catalyst d) 0.001 to 10, or 0.002 to 5, or 0.005 to 1 weight%.
  18. A method for producing a coating, comprising the steps of applying a crosslinkable composition according to claim 12 to at least a part of a means of transport and curing the applied crosslinkable composition at a temperature in the range of 5 to 180°C.
  19. A method for producing a coating according to claim 18, comprising optionally applying a first aqueous coloring layer onto a metal including an electrodeposited layer and then flash-off at a temperature below 90°C, then applying an aqueous basecoat layer, then another flash-off at a temperature below 90°C, then applying a clearcoat layer including a crosslinkable composition, and then a single high-bake curing step for all layers simultaneously at a temperature in the range of 80 to 180°C.

Description

Non-aqueous crosslinkable composition with improved appearance The present invention relates to a crosslinkable composition having an improved appearance and low VOC, comprising a polyol having free hydroxyl groups capable of reacting with a crosslinking agent, optionally a catalyst that catalyzes this reaction, and a polyurea rheological agent, and to the use thereof in coatings. In OEM clear coatings, the control of flow behavior—specifically the competitive processes of sagging and leveling—is perhaps the most critical and challenging aspect of their formulation. The problem is particularly severe when the paint is sprayed onto vertically oriented surfaces. The coating must be levelable to minimize surface irregularities or waviness, which result in a poorer appearance, and to develop the necessary appearance characteristics required for automotive finishes. During this process, sagging will occur. Since the factors governing sagging and leveling are necessarily opposite, designing a system with perfect leveling will result in severe sagging, whereas perfect sag control causes almost no leveling. Therefore, a compromise must be reached by balancing the factors affecting sagging and leveling. Generally, rheological agents, particularly those based on polyurea products, are used to help achieve this balance. The uses of polyurea-based rheological agents and polyols are described, for example, in EP0192304, US 4851294, US 4311622 and US20140378587. Leveling and increasingly improved appearance are of paramount importance in the current automotive OEM market. Not only are specifications for clearcoat coatings becoming more stringent, but rougher and less expensive substrates are also being used. Furthermore, as the flash and drying times of non-clearcoat layers are reduced, optimal leveling is often not achieved. Therefore, it is becoming increasingly important for clearcoat coating compositions to possess properties that conceal the roughness of the metal substrate. From US20080146720 and [BASF handbook on Basics of Coating Technology, pages 333-334], it is known that the greater the shrinkage of the clearcoat, the more pronounced the shift in this substrate roughness can be. A solution to reduce shrinkage would be to increase the solid content of the formulation. This is well known in radiation-curable coating formulations. However, in the case of temperature-curing spray formulations, this is less obvious. Increasing the solid content and formulating high solids clearcoat compositions can be achieved by reducing the molecular weight of the binder. However, unless the binder Tg is compensated for by more expensive, harder monomers, a lower molecular weight will result in a lower binder Tg. Consequently, lowering the molecular weight will have a severe impact on coating performance (Epple & Vogel, European Coating Journal, 07-08/2005, page 49). Furthermore, lower molecular weight also leads to lower binder viscosity, resulting in more sagging. Some high solids clearcoat coatings containing urea-based rheological agents have been described previously. US4528319 describes a high-solids sprayable clearcoat comprising a urethane binder, a melamine curing agent, and a flow control system comprising a urethane-urea polymer and silica particles. However, the sagging data shown in FIG. 1 of this patent indicates that such coatings do not provide sagging behavior and an acceptable balance according to today's standards. US8148460 describes a high-solids clearcoat containing rheological agents based on benzylamine and hexamethylene diisocyanate in the presence of a bismuth catalyst. Although data were not presented, it was claimed that the formulation provided a good balance. However, it was necessary to bake the composition at 130°C for 45 minutes, which is not permitted under today's standards. US8207268 and WO2006/074895 disclose clearcoat coatings formulated with a high solid content containing polyurea-based rheological agents. However, at this solid content, the viscosity was too high for spray application, making only draw-down application possible. Furthermore, the formulation did not provide a good balance as expected. Therefore, there is a clear need for clearcoat compositions, particularly high solids or low VOC compositions, that provide improved leveling and appearance, excellent sag resistance and other well-balanced related coating properties such as hardness, chemical resistance, flexibility and durability. The applicant has discovered a polyol component and a coating composition that overcome the disadvantages of the compositions described above and provide a combination of properties as described herein. Accordingly, the present invention relates to a polyol component comprising a) at least 35% by weight of a polyol a1) having a weight average molecular weight Mw of 1,000 to 4,000 daltons, a number average molecular weight Mn of 600 to 2,500 daltons, a hydroxyl value (OH value) of 80 to 300 mg KOH/1