Abrasion resistant coating for stacks of fiber cement siding

• US 7,238,391 B2
• Filed: 11/01/2001
• Issued: 07/03/2007
• Est. Priority Date: 11/01/2000
• Status: Expired due to Term

• Current Assignee: Axalta Coating Systems Ip Co Llc (Axalta Coating Systems Ltd.)
• Original Assignee: Valspar Sourcing, Inc. (Sherwin-Williams Company)
• Inventors: Dargontina, Jason E., Boespflug, Donald W.
• Primary Examiner(s): TRAN, THAO T
• Application Number:
  US10/000,057
• Publication Number:
  US 20020081437A1
• Time in Patent Office: 2,070 Days
• Field of Search: 427/372.2, 427/384, 427/385.5, 427/393.5, 427/393.6, 428/423.1, 428/446
• US Class Current: 427/393.6
• CPC Class Codes: B44C 5/04 Ornamental plaques, e.g. decorative panels, decorative veneers
• CPC Class Codes: B44C 5/0415 containing metallic elements
• CPC Class Codes: B44C 5/0438 containing stone elements
• CPC Class Codes: B44C 5/0461 used as wall coverings
• CPC Class Codes: C04B 20/0048 Fibrous materials
• CPC Class Codes: C04B 2103/54 Pigments; Dyes
• CPC Class Codes: C04B 28/02 containing hydraulic cements other than calcium sulfates
• CPC Class Codes: C04B 41/009 characterised by the material treated
• CPC Class Codes: C04B 41/4884 Polyurethanes; Polyisocyanates
• CPC Class Codes: C04B 41/52 Multiple coating or impregnating multiple coating or impregnating with the same composition or with compositions only differing in the concentration of the constituents, is classified as single coating or impregnation
• CPC Class Codes: C04B 41/70 for obtaining at least two superposed coatings having different compositions
• CPC Class Codes: E04F 13/16 of fibres or chips, e.g. bonded with synthetic resins , or with an outer layer of fibres or chips E04F13/0864 takes precedence
• CPC Class Codes: Y10T 428/249932 Fiber embedded in a layer derived from a water-settable material [e.g., cement, gypsum, etc.]
• CPC Class Codes: Y10T 428/31591 Next to cellulosic
• CPC Class Codes: Y10T 428/31598 Next to silicon-containing [silicone, cement, etc.] layer

Abstract

This invention relates to a novel stack of siding, comprising: first and second coated siding pieces comprising an outer topcoat layer, an inner decorative coating layer and a fiberboard cement substrate layer; and a liner positioned between the first and second coated siding pieces. The siding, during normal transportation and installation, retains an acceptable appearance that is substantially free of viewable scratches or mars. In more preferred embodiments, the outer topcoat layer of the siding has a thickness of at least 8 microns and comprises a polyurethane dispersion. The present invention also provides novel methods of pre-finishing a fiberboard cement siding product, comprising the steps of: providing a fiberboard cement substrate layer; coating a first major surface of the fiberboard cement substrate with a decorative coating; coating the exposed surface of the decorative coating with a topcoat layer; and curing the topcoat layer to provide an abrasion resistant siding. More preferably, the curing step comprises a process that does not require heating the siding to a board surface temperature in excess of 100° C.

Claims

1. A method of making a fiberboard cement siding product, comprising:

providing a fiberboard cement substrate,

coating a first major surface of the fiberboard cement substrate with a sealer;

coating the exposed surface of the sealer with a primer;

coating the exposed surface of the primer with a decorative coating;

coating the exposed surface of the decorative coating with a topcoat layer comprising a polyurethane dispersion; and

curing the topcoat layer to provide a mar and abrasion resistant coated fiberboard cement siding product;

wherein the curing step comprises a thermal curing process that does not expose the siding to a board surface temperature in excess of 100°

C.;

wherein the fiberboard cement substrate has a density of at least 1 g/cm³ and comprises wood pulp, silica and cement, and the outer topcoat layer has a dry thickness of at least 8 microns.

2. The method of claim 1, wherein the curing step comprises a thermal curing process that provides a board surface temperature of less than 100°

C.

3. The method of claim 2, wherein the thermal curing process provides a board surface temperature of less than 80°

C.

4. The method of claim 3, wherein the thermal curing process provides aboard surface temperature of less than 70°

C.

5. The method of claim 1 wherein the outer topcoat layer has a dry thickness of at least 10 microns.

6. The method of claim 1, wherein the topcoat layer further comprises an abrasion resistance promoting adjuvant.

7. The method of claim 1, wherein the topcoat layer has a dry thickness between 8 and 100 microns.

8. The method of claim 1, wherein the topcoat layer has a dry thickness between 8 and 50 microns.

9. The method of claim 1, wherein the topcoat layer has a dry thickness between 8 and 30 microns.

10. The method of claim 1, wherein the topcoat layer has a dry thickness of at least 10 microns.

11. The method of claim 9, wherein the topcoat layer has a dry thickness between 10 and 25 microns.

12. The method of claim 1, wherein the polyurethane dispersion is an aliphatic isocyanate-based polyurethane dispersion.

13. The method of claim 1, wherein the polyurethane dispersion comprises a polyurethane having a number average molecular weight of at least 1800.

14. The method of claim 13, wherein the polyurethane dispersion comprises a polyurethane having a number avenge molecular weight of at least 5000.

15. The method of claim 14, wherein the polyurethane dispersion comprises a polyurethane having a number avenge molecular weight of at least 9000.

16. The method of claim 1, wherein the polyurethane dispersion comprises a polyurethane having an acid number between 6.5 and 80 mg KOH per gram solid polymer.

17. The method of claim 16, wherein the polyurethane dispersion comprises a polyurethane having an acid number between 9 and 50 mg KOH per gram solid polymer.

18. The method of claim 17, wherein the polyurethane dispersion comprises a polyurethane having an acid number between 10 and 30 mg KOH per gram solid polymer.

19. The method of claim 1, wherein the topcoat layer has a pigment volume concentration of less than 20 percent.

20. The method of claim 19, wherein the topcoat layer has a pigment volume concentration of less than 15 percent.

21. The method of claim 1, further comprising stacking a first coated fiberboard cement siding product against a second coated fiberboard cement siding product.

22. A method of making a stack of fiberboard cement siding products, comprising:

preparing two or more coated fiberboard cement siding products, the method comprising;

providing a fiberboard cement substrate;

optionally coating a first major surface of the fiberboard cement substrate with one or more layers comprising a sealer, a primer, or both;

coating one or more layers of a decorative coating to the outermost surface of the optionally coated fiberboard cement substrate layer;

coating the exposed surface of the one or more layers of a decorative coating with a topcoat layer comprising a polyurethane dispersion;

curing the topcoat layer to provide a mar and abrasion resistant coated fiberboard cement siding product;

wherein the curing step comprises a thermal curing process that does not expose the siding to a board surface temperature in excess of 100°

C.; and

stacking the two or more coated fiberboard cement siding products to form a stack;

wherein the fiberboard cement substrate has a density of at least 1 g/cm³ and comprises wood pulp, silica and cement, and the outer topcoat layer has a dry thickness of at least 8 microns.