Wood treatment process

Details Wood treatment process Wood treatment process

1999-01-19

2001-08-14

Harrison, Robert H. (Department: 1619)

Coating processes

Vacuum utilized prior to or during coating

Organic base

C427S297000, C427S440000, C427S441000, C428S541000

Reexamination Certificate

active

06274199

ABSTRACT:

FIELD OF THE INVENTION
The invention pertains to a process for imparting water repellency to wood using water-based formulations which may also contain one or more wood preservatives.
BACKGROUND OF THE INVENTION
Processes for imparting water-repellency to wood substrates using water-based formulations, i.e. oil-in-water emulsions, are well known. Generally, such formulations may be applied by dip, brush or spray, but the modern trend is to impregnate the wood by means of a pressure process.
Water repellents have only a slight effect on the rate of absorption of water vapor in timber, but they can be very effective in reducing absorption of liquid water. They have no effect on the equilibrium moisture content of wood. The object of water repellent treatment of wood is to reduce the wettability of the wood surface so that liquid water does not form a coherent film and does not penetrate the surface structure between boards, and especially the permeable end grain. The process of the invention results in conferring superior water repellency to wood, thereby preventing the absorption of liquid water and providing a degree of dimensional stability and preventing rapid swelling and shrinkage during wetting and drying and is also effective in reducing the rate of mechanical degradation, surface checking and cracking in treated wood during initial drying or in service.
Typically, wood preservatives such as salts based on copper-chromium-arsenic are incorporated in the water-based formulations which provide water repellency to the wood in order to also impart resistance to fungal or insect attack to the wood.
Since the water-based formulations are emulsions of the oil-in-water type, the formulations will contain one or more surfactants to provide stability to the emulsion. Typically, such emulsions will contain one or more surfactants of the nonionic type.
Prior art processes for imparting water repellency to lumber generally are satisfactory when the lumber is derived from a species such as Southern Yellow pine or Radiata pine. However, prior art processes for imparting water repellency are unsatisfactory when the lumber is derived from a refractory species such as Ponderosa pine, Jack pine, Scots pine or Hem-fir, since there is an unacceptably low penetration of the water-based formulation (and any preservative that may be contained in the formulation) into such lumber.
The unsatisfactory penetration of water-based water repellent formulations, i.e. oil-in-water emulsions, into refractory wood species was previously believed to be due to the large particle size of the emulsions. However, it has now been discovered that the shear stability of the emulsion is critical to obtain a satisfactory degree of wood penetration, especially in refractory species.
OBJECTS OF THE INVENTION
It is an object of the invention to provide a process and a water-based formulation for imparting superior water repellency to wood.
It is a further object of the invention to provide a process and a water-based formulation for imparting water repellency to refractory wood species.
It is yet another object of the invention to provide for a process and a water-based formulation which has a high degree of shear stability, thereby facilitating penetration of the formulation into the wood substrate.
SUMMARY OF THE INVENTION
The objects of the invention can be achieved by utilizing a water-based formulation containing a wax, a nonionic surfactant, and optionally an anionic surfactant, an amphoteric surfactant, and/or an oil, and treating the wood substrate with such formulation at a temperature at or above that required to cause the wax to change into a molten state.


REFERENCES:
patent: 3378381 (1968-04-01), Dragnov et al.
patent: 3832463 (1974-08-01), Nicholson
patent: 3945835 (1976-03-01), Clarke et al.
patent: 4085251 (1978-04-01), Rak
patent: 4407076 (1983-10-01), Estberg
patent: 4464848 (1984-08-01), Estberg
patent: 4486475 (1984-12-01), Shutov et al.
patent: 4612255 (1986-09-01), Hein
patent: 4643860 (1987-02-01), Knudson et al.
patent: 5013748 (1991-05-01), Radtke et al.
patent: 5468284 (1995-11-01), Sturm
patent: 2179001 (1997-02-01), None
patent: 1181246 (1970-02-01), None
patent: WO 89/10956 (1989-11-01), None

Affiliated with

Also associated with

Rating

Wood treatment process does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Wood treatment process, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Wood treatment process will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-2520466