Process for the preparation of coatings with specific surface properties

A coating and powder coating technology, which is applied in the field of controllable surface appearance of powder coating substrates, can solve the problems of difficult control and poor efficiency of technical solutions, and achieve the effect of high mechanical stability and high outdoor stability

Inactive Publication Date: 2008-11-12
EI DU PONT DE NEMOURS & CO
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0007] However, these technical solutions are often uncontrollable or inefficient

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment UA1

[0055] Preparation of Amorphous Polyurethane Acrylate UA1

[0056] In a three-necked glass flask with thermocouple, stirrer and metering funnel, add 58.7% by weight isophorone diisocyanate, 0.18% by weight toluhydrochinone (toluhydrochinone), 0.02% dibutyltin dilaurate, and heat to 65 ℃. 16.5% by weight of neopentyl glycol was added while being careful not to exceed 90°C. After the metered addition, the mixture was heated to 100° C. and kept at this temperature until an NCO value of less than 11.8% was reached. At a temperature of 100-110° C., 23.3% by weight of hydroxyethyl acrylate was added. The reaction mixture was kept at 110° C. until the NCO-value reached below 0.45%. Afterwards, 1.3% by weight of hydroxybutyl acrylate was added. The reaction mixture was kept at 110° C. until an NCO-value of less than 0.1% was reached. The resin swells and solidifies into a transparent, colorless, amorphous resin.

Embodiment UA2

[0058] Preparation of Polyurethane Acrylate UA2 Modified by Siloxane

[0059] The silicone modified urethane acrylate was prepared using the same procedure as described in UA1. The only difference is the mole exchange of neopentyl glycol for linear telechelic α,ω-dihydroxypolydimethylsiloxane (TegomerHSi-2111 from Tego).

Embodiment 1

[0061] Preparation of the powder coating of the present invention

[0062] A clear coating composition was prepared by dry mixing the following ingredients: 80% by weight amorphous polyurethane acrylate UA1, 1% by weight Irgacure 2959 (photoinitiator), 1 wt% Tinuvin 144 (UV absorber) and 18% by weight silicone-modified urethane acrylate UA2. The coating formulation was loaded into a twin-screw extruder, and the temperature of the extruder was set at 95-100°C. After extrusion, the melt is cooled on a cooling belt, and the resulting product is crushed into small pieces. The flakes are ground to a suitable particle size distribution for spray application, which ranges from 20 to 80 μm.

[0063] Then, spray the powder onto the metal coil test plate with a triboelectric spray gun until the film thickness is 80-90 μm.

[0064] With a medium pressure mercury (Hg) lamp (240W / cm molten emitter), use 500mJ / cm 2 The applied powder (dry state) was irradiated with a UV dose of .

...

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PUM

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Abstract

A process for the preparation of powder coatings with a controlled surface appearance comprises the steps of applying a powder coating composition onto the substrate surface comprising 1 to 95 wt% of at least one hydrophobic agent, irradiating the applied powder coating composition with high energy radiation having a UV dose in a range of 100 to 5000 mJ / cm 2 under near-ambient temperature, fusing, melting and flowing out the particles of the powder coating composition by increased temperature to a molten coating, and curing the molten coating; the process according to the invention makes it possible to provide coatings with a controlled surface appearance as well as to provide coatings having a high mechanical and outdoor stability without a change in formulation of the powder coating composition.

Description

technical field [0001] The present invention relates to a method for producing a controlled surface appearance of a powder-coated substrate by using a high-energy radiation-curable powder coating composition. Background technique [0002] Powder coatings that can be cured by high energy radiation, such as ultraviolet (UV) light, have been developed for many years. Typically, these compositions contain a base resin having ethylenically unsaturated groups and a specific photoinitiator to initiate photopolymerization. This makes it possible for the composition to cure in a very short time and at low operating and equipment costs, improving quality and productivity. [0003] Currently, surface appearance control and matting of UV-powder coatings, as well as maintaining these excellent process properties of UV-coatings are still difficult tasks. [0004] The use of matting agents to adjust the matting effect to a desired level is known, see WO03 / 102048, US2003 / 0134978, EP-A1129...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C09D5/03B05D3/02
CPCB05D3/067B05D3/0209C09D5/033Y10T428/31504B05D3/0254C09D5/032
Inventor U·威尔肯赫纳M·乌尔夫C·弗洛斯巴赫
Owner EI DU PONT DE NEMOURS & CO
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