Compositions: coating or plastic – Coating or plastic compositions – Carbohydrate or derivative containing
Reexamination Certificate
2000-05-30
2003-04-15
Brunsman, David (Department: 1755)
Compositions: coating or plastic
Coating or plastic compositions
Carbohydrate or derivative containing
C106S217200, C106S287170, C106SDIG003, C524S423000, C524S425000, C524S431000, C524S445000, C524S446000, C524S449000
Reexamination Certificate
active
06547868
ABSTRACT:
FIELD OF INVENTION
The present invention relates to a scratch resistant acoustical coating for an acoustical panel and more particularly to a scratch resistant discontinuous primer coating for an acoustical panel.
BACKGROUND
As the service sector of the economy grows, more and more workers find themselves in offices rather than in manufacturing facilities. The need for flexible, reconfigurable space has resulted in open plan workspaces, large rooms with reduced height, moveable partitions and suspended ceiling systems. Workstation density is also increasing, with more workers occupying a given physical space. Additionally, speakerphones, conferencing technologies, and multimedia computers with large, sound reflecting screens and voice input tend to increase the noise level of the workplace.
In closed spaces, particularly in office and meeting room settings, speech intelligibility and acoustic performance are determined by a variety of factors, including room shape, furnishings, number of occupants, and especially floor, wall and ceiling treatments. This acoustic environment determines how much sound intrusion occurs as well as the affect on listeners by extraneous noise.
Such acoustical environments are typically modified using acoustical surfaces having sound absorbing qualities. A common sound absorbing surface in a building is found in the acoustic panels used to cover the ceiling, wall or other surface. Acoustic panels are generally composed of porous layers of mineral or vegetable fibers bonded together with non-thermoplastic resins. The panels may also be composed of glass fibers. Acoustic panels are typically provided with substantial porosity to absorb sound waves emanating from within a room. Porosity is evidenced on the surface of the acoustic panels by the presence of small recesses or pores of varying diameter which permit sound waves to enter the material and be dispersed. Additionally, the panels may be acoustically enhanced by mechanical texturing. This texturing produces small holes in the surface of the panel to admit sound which is either dissipated in the interior of the panel or transmitted through the panel.
In the manufacture of acoustical ceiling panels, it is usually necessary to apply colored coatings to the surface of acoustical ceiling panels. Aesthetic finishes are achieved by a combination of texturing and painting the surface of the panel. Achieving a desired coloration of the panel material may require the application of several layers of paint or pigmentation and a primer layer to provide a standard base color and adhesion for additional layers.
The raw materials comprising acoustical panels typically have poor durability and scratch resistance leading to marring of the finished product. To prevent such marring, a coating can be added to provide increased durability to the surface of the panel. Coatings can also be added to limit flammability and flame spread.
Furthermore, moisture and high-humidity can cause a weakening of the material comprising acoustical ceiling panels. This may cause a panel to sag in the middle. Coating one or both surfaces of a panel can both reduce the penetration of moisture into the panel, and impart additional tensile strength to reduce sagging.
Unfortunately, coatings applied to the room-side surface of the panel tend to clog the pores or holes that are necessary for good acoustical performance, thus impairing the acoustical performance of the panel.
Thus, there is a need for a coating that leaves open the sound absorbing pores of an acoustical panel such that there is no appreciable effect on the acoustic performance of a panel. Additionally, there is needed a coating capable of providing a scratch resistant surface to a panel while also providing improved adhesion for applied coatings.
SUMMARY
The present invention provides for both a composition and method for producing a scratch resistant discontinuous primer coating on an acoustical panel. Acoustical panels can be any manufactured surface having sound attenuating properties, such as acoustical ceiling tiles, room partitions or highway barriers.
The applied coating primarily comprises binder, filler and mica and is typically applied as a spray. The coating can be characterized as a discontinuous film, whereby sound can pass through the coating to the panel for attenuating sound.
The coating provides a durable finish and increased handleability along with color without compromising the acoustical performance of the substrate. Handleability is an important aspect of panel durability. Related to handleability are the metrics of Modulus of Rupture (MOR) and Modulus of Elongation (MOE), which relate to the structural integrity of a material, which is also increased by the coating of the present invention.
In more detail, the discontinuous acoustical surface coating of the present invention on a dry weight percent basis comprises about 4 to about 80% mica, about 10 to about 45% binder; and about 10 to about 86% filler. The filler is typically clay and the binder is typically starch.
The process primarily comprises combining and mixing the dry components of filler, binder and mica and then combining the same with water and mixing to create an aqueous mix that can be applied to the acoustical panel and dried.
The method for creating a discontinuous acoustical surface coating comprises the steps of combining and mixing mica, filler and binder to form a dry mix which comprises about 4 to about 80% mica, about 10 to about 45% binder, about 10 to about 86% filler. Then the dry mix can be combined and mixed with water to form a wet mixture that is then sprayed onto the panel to form a coated panel. The components may also be mixed together in one step and then sprayed onto the coated panel. The coated panel is either air dried or heated in an oven.
DETAILED DESCRIPTION
The present invention provides for both a composition and method for producing a scratch resistant coating applied to an acoustical panel. The coating primarily comprises binder, filler and mica and is typically applied as a spray. The coating can be characterized as a discontinuous film whereby sound can pass through the coating to the panel for attenuating sound. Discontinuity is provided by pores formed by the filler component. The coating is thus enabled to provide a finish and color without compromising the acoustical performance of the substrate.
Additionally, the discontinuous acoustical coating primes the surface of the panel. As a primer, the coating adds adhesion between the substrate and successive layers.
In an embodiment, the composition of the coating comprises mica, clay as a filler and starch as the binder. In the coating, mica can comprise from about 4% to about 80% by dry weight of the coating and alternatively between about 4% to 25% by dry weight. In one embodiment, mica comprises about 8% by weight of the coating. Experimentation has indicated that as mica is added in amounts over 80%, the probability of sound permeability of the resulting coating being decreases to an NRC of less than 0.50 at the lower stated application rates increases.
Clay or filler can comprise between about 10% to 86% by dry weight of the coating and alternatively between about 10% to 55% by weight. In one embodiment, the filler comprises about 77% by weight of the coating. The filler is substantially responsible for creating the voids within the coating which allow sound to pass though the coating to the panel where it is dissipated.
Starch or binder can comprise between about 10% to about 45% by weight of the coating and alternatively between 10% to 30% by weight. In one embodiment, starch can comprise about 15% by weight of the coating. The binder or starch is combined with the mica to create the primer coating with significantly improved “finger scratch” results (approximately one to two rating points).
An example of a mica comprising the coating includes Mica 325, available from Franklin Industrial Minerals, of King Mountain, N.C. The average particle size of the mica can range from 20 to 100 150 microns. Additi
Belmares Hector
Caldwell Kenneth G.
AWI Licensing Company
Brunsman David
Womble Carlyle Sandridge & Rice PLLC
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