Plant protecting and regulating compositions – Plant growth regulating compositions – Aquatic plant regulator
Reexamination Certificate
2001-10-11
2003-11-18
Clardy, S. Mark (Department: 1616)
Plant protecting and regulating compositions
Plant growth regulating compositions
Aquatic plant regulator
C504S161000, C504S348000, C514S705000, C428S540000, C428S541000
Reexamination Certificate
active
06649567
ABSTRACT:
FIELD OF THE INVENTION
The invention relates to the treatment of porous masonry and wood surfaces to control algal defacement by the application of a microbicidal composition.
BACKGROUND
Microbial colonization of masonry construction materials significantly contributes to defacement and weathering. This can be caused by a diverse community of microorganisms that includes bacteria, fungi and algae. Growth of these organisms and thus the severity of defacement and biodeterioration is dependent on many factors, including porosity of the masonry material, pore size and distribution, permeability, effective pH, surface charge, nutrient availability, presence of light, temperature and relative humidity and wetting by rain.
Physiochemical characteristics such as the porosity, pore size distribution, permeability, surface charge and alkalinity vary from material to material and even within samples of the same material. These characteristics can affect the performance of biocidal treatments. Consequently, performance and effective application-rate ranges must be based on the response of treated porous masonry and wood substrate materials to microbial challenge.
Typical approaches to the control of microbial growth on or from within masonry materials are (1) limitation of the moisture content of the construction material using water repellants, and (2) treatment with microbicidal chemicals. Chemical treatments that have been used with some success are: hypochlorite, organotin, organomercurial, quaternary ammonium salt, chlorinated phenolic, borate and phosphoric acid. The use of many of these chemical biocides has been restricted or entirely banned due to concerns for significant environmental impact. Some of the chemical treatments may not be supported under the European Union Biocidal Products Directive due to high costs.
Extreme cases of defacement have been observed of newly-constructed masonry surfaces (non-painted) and freshly painted masonry by algae commonly encountered in the warm humid climates of the Pacific Rim and Mediterranean regions of the world. Similar defacement has also been reported in temperate regions. If left untreated for an extended period of time, the masonry substrate can incur permanent damage, leading to attendant costs for repair and replacement.
It is known from U.S. Pat. No. 5,917,094 that a 2-propenal-releasing emulsion homopolymer can be produced by adding 2-propenal that is at least 95% by weight pure, to a composition of an alkali hydroxide under specified conditions, and then adjusting the pH to the range of from 5 to 7. The only use disclosed for such 2-propenal homopolymers are in aqueous systems, such as paints and other architectural coatings. The 2-propenal is released when a pH is greater than 7, thereby producing a biocidal affect in these systems. A controlled release of 2-propenal to maintain apparently minimum effective limit value of 0.7 ppm in the aqueous systems tested reportedly exceeded 400 days.
It is known from the prior art to use a 2-propenal copolymer as an in-can preservative to prevent spoilage of aqueous liquid products, such as decorative coatings, adhesives, metal working fluids and inks. When used in these industrial applications the 2-propenal copolymer is supplied in the form of an aqueous composition at about 50 weight percent as the copolymer and is mixed with the aqueous liquid composition, typically in a percentage by weight in the range of from about 0.25% to 1%.
It is also known from the prior art to add 2-propenal molecular or oligomer form to outdoor containments lined with polymer membranes, waste water storage, and treatment ponds and drainage ditches to control the growth of water-borne algae. Such applications do not appear to have included use of a 2-propenal copolymer.
The art has not been found to disclose the use of a copolymer of 2-propenal for application to solid porous surfaces to prevent the defacement of the surface by organisms that colonize such surfaces, e.g., terrestrial algae.
It is therefore a principal object of the invention to provide a safe and efficacious method for applying an environmentally benign composition having anti-microbial activity as an algacidal treatment for masonry and wood surfaces subject to algal growth and defacement.
It is also an object of this invention to provide a quantitative application rate for 2-propenal copolymers that will provide extended time-release anti-microbial protection for the surface of porous construction materials exposed to algal growth and defacement.
SUMMARY OF THE INVENTION
The above objects and other benefits and advantages are attained by the practice of the method of the invention in which a time-release aqueous biocidal composition of a 2-propenal copolymer is applied to the porous surface of a construction material selected from the group consisting of stone, concrete, brick and wood and the biocidal composition is maintained in contact with the porous surface for a sufficient period of time to saturate a portion of the construction material below the surface with the biocidal composition. The surface of the construction material is then allowed to dry.
If desired, after drying the surface of construction material can be coated with a decorative architectural coating, or paint.
As used herein, the term “2-propenal copolymer” means a composition of 2-propenal prepared in accordance with the disclosure of U.S. Pat. No. 6,060,571, the disclosure of which is incorporated herein by reference. A particularly preferred composition is the reaction product of 2-propenal and propylene 1,2-glycol prepared in accordance with Example 4 of U.S. Pat. No. 6,060,571 as described below.
In a preferred embodiment, the biocidal compound constitutes at least about 0.25% by weight of the aqueous composition applied to the construction material. In an especially preferred embodiment the 2-propenal copolymer is about one percent by weight of the applied composition.
The aqueous biocidal composition can be applied by conventional methods including spraying, brushing and dispensing a liquid stream from a horizontal feed line and allowing the composition to stream down the face of an existing structure.
In a particularly preferred embodiment, new construction materials are treated by immersing the construction material in a bath of the biocidal composition, or by dipping or soaking one of more of the surfaces of the material that will be exposed to biological growth in a treatment zone containing the biocidal composition. This method of application is particularly effective and efficient, since the duration of the soaking time in the specific concentration of the biocidal composition can be used to provide the desired degree of time-release protection. The depth of penetration and saturation can be determined from a relatively small sample of the particular construction material, whether it be a natural stone such as sandstone, a fired brick, a section of pre-cast concrete or so-called cast stone or any of the various species of wood that are used for construction. The immersion, dipping and soaking methods of application also have the particular advantage of assuring a uniform concentration of material over the entire surface treated, thereby avoiding potential problems is associated with the application of the aqueous biocidal composition by brushing or spraying to existing structures.
In a further preferred method of practicing the invention for providing a time-release protection to new construction materials, the individual elements, i.e., bricks, natural stone, concrete blocks or pre-cast articles, wood, or the like, are conditioned to a uniform moisture content prior to application of the biocidal copolymer composition. For example, when construction materials are stored in a climate having high humidity, it is preferred to dry at least the surface to be treated with the biocidal copolymer composition to dry out excessive moisture so that the region at the exposed surface can absorb the optimum volume of the applied composition.
It is well known in the wood
Abelman ,Frayne & Schwab
Clardy S. Mark
ISP Investments Inc.
LandOfFree
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