Method of drying substrates and use thereof

• US 6,203,859 B1
• Filed: 09/08/1997
• Issued: 03/20/2001
• Est. Priority Date: 09/24/1993
• Status: Expired due to Fees

• Current Assignee: Optimum Air Corp
• Original Assignee: Optimum Air Corp
• Inventors: Scheufler, Fred G., Bayard, William H.
• Primary Examiner(s): Parker, Fred J.
• Application Number:
  US08/925,347
• Time in Patent Office: 1,289 Days
• Field of Search: 134/37, 427/384, 427/475, 427/315-318, 427/322, 427/325, 427/327, 427/195, 427/372.2, 427/377, 427/486, 343/43, 344/75, 344/87, 344/91, 34/77, 34/78, 34/30, 34/37, 344/46, 345/65, 345/66, 345/67, 345/70--71
• US Class Current: 427/475
• CPC Class Codes: B01D 2267/40 Different types of filters
• CPC Class Codes: B01D 46/12 in multiple arrangements
• CPC Class Codes: B01D 46/446 by pressure measuring
• CPC Class Codes: B01D 50/00 Combinations of methods or devices for separating particles from gases or vapours
• CPC Class Codes: B01D 53/261 by adsorption
• CPC Class Codes: B01D 53/265 by refrigeration (condensation)
• CPC Class Codes: B05B 14/43 by filtering the air charged with excess material
• CPC Class Codes: B05B 16/60 Ventilation arrangements specially adapted therefor
• CPC Class Codes: B05D 3/002 Pretreatement
• CPC Class Codes: B05D 3/0413 Heating with air
• CPC Class Codes: F26B 21/003 Supply-air or gas filters
• CPC Class Codes: F26B 21/083 by using sorbent or hygroscopic materials, e.g. chemical substances, molecular sieves
• CPC Class Codes: F26B 21/086 by condensing the moisture in the drying medium, which may be recycled, e.g. using a heat pump cycle
• CPC Class Codes: Y02P 70/10 Greenhouse gas [GHG] capture, material saving, heat recovery or other energy efficient measures, e.g. motor control, characterised by manufacturing processes, e.g. for rolling metal or metal working

Abstract

A method is provided for washing, drying, applying a curable coating, and effecting the cure of such coating on a variety of substrates, such as metal, for example steel, plastic and wood. A particularly effective drying procedure based on the generation of a dehumidified and filtered air stream directed substantially parallel to the wet substrate allows for a significant decrease in drying time while maintaining coating effectiveness.

Claims

1. A method for effecting water removal from an exposed wet surface of a substrate selected from the group consisting of metal, plastic, and wood, the method comprising the steps of:

washing the substrate;

placing the substrate in a drying booth in a batchwise or continuous manner;

drying the substrate by continuously generating and circulating within the drying booth, a dehumidified and filtered air stream, wherein the air stream is directed in a substantially parallel manner at a rate of at least 50 ft per minute across the substrate surface in the drying booth and has an RH value of at least about 9% at a temperature up to 105°

F.; and

providing at least one humidity sensing device within the drying booth to monitor an RH value of the air stream and disable the circulation of the air stream within the drying booth when the RH value of the air stream reaches a predetermined value.

2. The method in accordance with claim 1, where water is removed from an exposed wet surface of steel.

3. The method in accordance with claim 1, further comprising electrostatically coating dry steel substrate with charged powder which is thereafter cured.

4. The method in accordance with claim 1, further comprising painting dry steel substrate with an aqueous based air curable paint after the drying step.

5. The method in accordance with claim 1, wherein the substrate is a dry thermoset plastic.

6. The method in accordance with claim 5, wherein the dry thermoset plastic substrate is a polyimide.

7. The method in accordance with claim 1, further comprising coating the substrate with a curable material selected from the group consisting of a heat curable powder coating composition and an air curable aqueous based paint after the drying step.

8. A method for removing moisture from an exposed wet surface of a substrate, the method comprising the following steps:

wetting the substrate;

placing the substrate in a drying booth in a batchwise or continuous manner;

drying the substrate by continuously generating and circulating within the drying booth, a dehumidified and filtered air stream having a temperature up to about 105°

F.;

selecting and maintaining an RH value of the air stream of at least about 9% using a device within the drying booth;

diverting the circulation of the air stream from the drying booth when the RH value of the air stream reaches a predetermined value; and

coating the substrate approximately less than ten minutes after the drying step.

9. The method in accordance with claim 8, wherein the coating step comprises the step of coating dry steel substrate with charged powder.

10. The method in accordance with claim 8, wherein the coating step comprises the step of painting dry steel substrate with an aqueous based air curable paint.

11. The method in accordance with claim 8, wherein the substrate is a dry thermoset plastic.

12. The method in accordance with claim 11, wherein the dry thermoset plastic substrate is a polyimide.

13. The method in accordance with claim 8, wherein the coating step comprises the step of coating the substrate with a curable material selected from the group consisting of a heat curable powder coating composition and an air curable aqueous based paint.