Stock material or miscellaneous articles – Composite – Of addition polymer from unsaturated monomers
Reexamination Certificate
1999-03-29
2002-05-07
Hampton-Hightower, P. (Department: 1711)
Stock material or miscellaneous articles
Composite
Of addition polymer from unsaturated monomers
C428S220000, C428S506000, C428S508000, C428S510000, C428S514000, C427S372200
Reexamination Certificate
active
06383652
ABSTRACT:
TECHNICAL FIELD
The present invention relates to weatherable building products made of wood members coated with a weatherability coating composition.
BACKGROUND ART
Wood members have long been used in the manufacture of building products. Examples of such building products include, but are not limited to, door jambs, end rails, stiles, rails, and compression molded door skins, interior and exterior trim products, pilasters, railings and posts, stairs, mull posts, dimensional members, thresholds, brickmould, ultra-light-, medium- or high-density fiberboard, oriented strand board, laminated strand lumber, laminated beams, plywood, particle board, and plastic wood. These wood members can be made from solid wood or fiber-based materials. By fiber-based materials, it is meant, wood fiber or fibers of agricultural, waste, and recylate byproducts.
People appreciate these building products formed of wood members because of their relatively inexpensive cost, structural strength properties, and warm feel. However, building products formed of wood members are susceptible to damage due to exposure to water, moisture and sunlight.
For instance, unprotected wood members weather relatively rapidly as soluble sugars are leached by water and scissioned by ultraviolet light in sunlight. Within two or three months, the surfaces of most wood members exposed to the weather are damaged sufficiently so as to be unpaintable.
In addition, many wood members expand and contract significantly in equilibration with ambient humidity. The result in the building industry may include the following few examples:
remanufacturing techniques used on small undesirable scraps of wood members, such as fingerjointing, often fail during two or three months exposure to direct water contact or moisture vapor;
thin veneers often bubble and peel off when a combination of moisture vapor and direct water wicking in the substrate cause swelling of the substrate or stresses within the thin veneers; and
thick veneers or capstocks often fail at the adhesive line due to differential linear expansion of the two substrates due to humidity response.
Compounding this expansion phenomenon is that the percentage of expansion approaches an asymptotic relationship when standing water reaches the wood member or when very high or very low relative humidity levels are achieved. Such elevated relative humidity levels are very common in the southern U.S. costal and island regions in the summer as well as the northern Great Plains regions during winter.
A quantifiable measure of the degree of damage wood members can experience from exposure to water can be determined by ascertaining the percent moisture linear expansion according to ASTM No. D-1037. The acceptable percent moisture linear expansion will vary for each building product depending on a variety of factors. These factors include, but are not limited to, type of building product, type of wood member, allowable tolerance, and presence of expansion inhibitors, such as the mechanical coupling with other members. For instance, it has been determined that successful Medium Density Fiberboard (MDF) compression mold door skins for doors having a wood frame and having a polyurethane core, require that moisture linear expansions be less than about 0.1% for the skins, and more preferably about 0.0-0.05% to inhibit warping or cupping in the doors when assembled. In door entries, which include a door hingedly connected with a frame comprising a plurality of jambs, the traditional gap between the door and each jamb is less than about 2.3 mm on a 2.4 m high door. Thus, the net moisture linear expansion for such door entries must be less than about 0.01%, and preferably less than about 0.005%.
Accordingly, it would be desirable to be able to provide weatherable building products made of wood members which are relatively resistant to damage from exposure to water, moisture, and sunlight. Typically, it is desirable to provide weatherable building products made of wood members which have moisture linear expansions of less than about 0.1%. It would be further desirable to provide weatherable compression molded door skins formed of wood members having moisture linear expansions of less than about 0.1%, and preferably less than about 0.05%. It would also be desirable to provide weatherable door entries made of wood members having moisture linear expansions of less than about 0.01%, and preferably about 0.005%.
Moreover, it would be further desirable to provide weatherable building products made of wood members that will withstand attacks from moisture vapor, direct water, and sunlight and perform well in weatherability tests while remaining readily machined and manipulated by typical household and building trade equipment and which retain paint, primers, and stain finishes in a manner similar to prior art building products as well as meet or exceed the structural properties of prior art building products.
DISCLOSURE OF INVENTION
The present invention comprises a weatherable building product made of wood members coated with a weatherability coating composition. The present invention also comprises a method for making a weatherable building product comprising coating a wood member with a weatherability coating composition.
The wood member can be made of solid wood or fiber-based materials such as, wood fiber or fibers of agricultural, waste, and recylate byproducts. A final coating of paint, primer, stain or other ultraviolet light-opaque covering may be applied to all surfaces of the weatherable building product.
In a preferred embodiment, the weatherability coating composition comprises an interpenetrating polymer network of an acrylic latex and a vinylidene chloride polymer. In a second embodiment, the weatherability coating composition is selected from the group consisting of polyurethane and acrylic-urethane hybrid polymers.
BEST MODE FOR CARRYING OUT THE INVENTION
The present invention relates to weatherable building product made of wood members which are resistant to water penetration and degradation due to water, moisture, and sunlight, and to a method of making weatherable building products. Examples of such building products include, but are not limited to, door jambs, end rails, stiles, rails, and compression molded door skins, interior and exterior trim products, pilasters, railings and posts, stairs, mull posts, dimensional members, thresholds, brickmould, ultra-light-, medium- or high-density fiberboard, oriented strand board, laminated strand lumber, laminated beams, plywood, particle board, and plastic wood. By wood members, it is meant at least one member made from solid wood or fiber-based materials such as, wood fiber or fibers of agricultural, waste, and recylate byproducts. The weatherability coating composition is preferably applied to the wood member after the wood member has been manufactured into the finished building product. The wood members preferably have average thicknesses of at least about 0.5 mm, more preferably less than about 75 mm, even more preferably about 0.75 mm to about 45 mm.
The wood members made of solid wood can be made of either hardwood or softwood. The wood preferably has a moisture (water) content of less than about 20 weight percent, more preferably about 4-12 weight percent, and most preferably about 6-9 weight percent. The wood is preferably dried in an oven, and more preferably a kiln-type oven to achieve such moisture content. Examples of usable woods include, but are not limited to, Ponderosa pine, oak, maple, ash, poplar, radiata pine, southern yellow pine, and cedar. The wood members can be either unitary wood members of pieced together wood members, such as finger-jointed wood members.
The wood members made of fiber-based materials can be made of wood fiber, wood fiber-wood flour mixtures, fibers of agricultural, waste, and recyclate byproducts, and mixtures thereof. The fiber-based materials are moldable or extrudable under heat and pressure to form building products, such as compression molded door skins or oriented strand board, by methods which
Brooks S. Hunter W.
Minke Ronald C.
Porter Cem A.
Templeton G. Daniel
West Kenneth J.
Brooks & Kushman P.C.
Hampton-Hightower P.
TT Technologies, Inc.
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