Stock material or miscellaneous articles – Structurally defined web or sheet – Continuous and nonuniform or irregular surface on layer or...
Reexamination Certificate
1999-04-26
2003-02-04
Watkins, III, William P. (Department: 1772)
Stock material or miscellaneous articles
Structurally defined web or sheet
Continuous and nonuniform or irregular surface on layer or...
C428S149000, C428S325000, C404S014000, C359S539000, C359S540000, C106S676000, C106S691000, C106S712000, C106S716000
Reexamination Certificate
active
06514595
ABSTRACT:
TECHNICAL FIELD
The present invention relates to integrated retroreflective marking materials for fresh or hardened concrete and asphalt surfaces, such as roads, highways and the like. The present invention relates particularly to cementitious material formulations which contain a redispersible polymer and retroreflective/reflective materials.
BACKGROUND OF THE INVENTION
Currently, the marking of concrete and asphalt for lane striping or cautionary markings is generally accomplished by painting stripes or applying preformed tapes of polymeric material. Disadvantages of these methods include the fact that both are temporary, requiring frequent, periodic reapplication.
To provide a longer lasting product, several marking methods include using a system which consists of a two part epoxy, thermoplastic, polyester, methyl methacrylates, or polyurethane resin system. Most of these products are solvent based or reactive resins which require special handling, storage, mixing, application and disposal procedures. With solvent-borne paint products, including the typical one-part traffic paint, the release of solvent into the environment with each application presents certain hazards to the environment as well as for nearby workers and applicators.
In some situations, retroreflectivity of the markings is desired, for enhanced night-time visibility. This has been proposed to be accomplished by several techniques. In one technique, preformed reflector devices are partially embedded in the roadway at regular intervals. The exposed portion of the reflector soon gathers a deposit of dirt or silt, which reduces visibility. The exposed portion of such a reflector may be damaged and worn away with repeated contact with vehicle tires, and cleaning or snow removal equipment.
Another technique is to precast a panel of concrete having reflective or retroreflective materials embedded into its surface, and then to position or affix the panel to the roadway surface or highway barrier. This requires custom prefabrication of the structures, and storage, transportation and placement of the heavy articles.
One onsite highway marking technique involves broadcasting a quantity of reflective or retroreflective materials onto the surface of a coating of paint applied to the surface of the roadway, optionally including a second coating of paint to lock in the particles. Similarly, it has been proposed to broadcast reflective glass beads onto a bonding polymer coating (such as epoxy) on the roadway, followed by application of a weathering top coat (such as a urethane). Again, these road markings are temporary, and require frequent reapplication.
A variant of the marking tape technique has been proposed, in which several layers of polymeric materials are adhesively bonded in the tape, at least one of which carries transparent microspheres or other reflective elements. In a related proposal, a single layer of polymeric tape carries embedded ceramic spheroids, to be used for marking lines on roadways.
These tapes are also temporary in nature, rapidly wearing due to the friction of vehicle tires, or pealing away from the roadway because of such friction or poor adhesion to the road surface. Due to the fact that these tapes are polymeric, they have different thermal properties than the substrate to which they are applied. In hot weather for example, preformed tapes tend to soften, collect debris, crack and delaminate. They can also require an epoxy-bonding agent to improve adhesion to the substrate. This complicates the application to the pavement, and introduces yet another thermally dissimilar material to the system.
Australian Patent 667210 proposes a surface coating composition for road marking, delivered to the site in two parts, one being a dry blend and the other being a liquid mixture. The dry blend includes white portland cement, titanium dioxide, refractory cement, and aggregate in the form of 150 to 600 micron sized garnet, or 250 to 600 micron sized garnet and 150 to 600 micron sized glass spheres. The liquid mixture includes acrylic cement polymer modifier, acrylate/styrene copolymer cement modifier, foam control agent, non retarding mortar, plasticiser and water. The two components are mixed onsite, and applied to the road as a paste. A stream of glass beads, 0.85 mm to 1.18 mm (850 to 1180 microns) in size are sprayed onto the paste to partially embed them for reflectivity.
There are several shortcomings with the marking material described in the Australian Patent. First, the fact that the marking material is a two phase system introduces variability and the possibility of improper dosage during the on site preparation of the paste to be applied to the roadway. The liquid portion, being susceptible to uncertain loading level, and being susceptible to spillage, is of concern to the environmental and structural integrity of the worksite. One must rely on the road crew to correctly measure and thoroughly mix the liquid and dry portions of the system, even if one could be sure that the correct loading levels of ingredients were present in the liquid portion.
Even if the liquid portion is pre-proportioned, it has to be mixed with additional water to achieve the desired workability. If the correct amount of water is not added, both the plastic and hardened properties of the finished product will be compromised. If the consistency of the marking material is too wet or too dry, the use of a liquid polymer as a primary component does not allow for any adjustments in dosage without affecting the performance of the finished product. The proportion of polymer in the marking material disclosed in the Australian Patent is quite high, raising concerns about the strength and abrasion resistance of the resulting product. The high polymer level also causes set retardation as evidenced by the use of a stream of hot air to accelerate the setting time and embed the glass beads. The hot air can cause rapid drying of the surface and differential hydration of the cement.
The glass spheres incorporated in the mixture of the marking material is more suitable for utility as an aggregate for the cementitious component, rather than promoting dry and wet night-time visibility and retroreflection, once the surface-borne glass beads are worn. Also, due to the ratio of garnet to glass beads used in the material, the small proportion of integral beads would be overshadowed by the larger and darker mineral aggregate after the surface is worn.
It would be preferred that a cementitious marking material be formulated as a one phase system, preferably a dry system, to ensure that the component levels were precise and uniform throughout, and to avoid storage restrictions (such as to prevent freezing) and transport of large quantities of liquid product with its attendant disadvantages of added cost and the need for disposal of plastic packaging containers.
However, the use of a significant portion of dry polymeric materials in cementitious mixtures presents other disadvantages. The polymer needs to be wetted out before use. The polymer often acts as a retarder for the system, and additionally, entrains more air in the cementitious mixture. Also, the polymer often presents a foaming problem.
It is therefore an object of the present invention to provide a marking material for fresh or hardened concrete or asphalt applications that is integrated, versatile in its mode of application, and long lasting with respect to the marked concrete or asphalt surface.
It is a further object of the present invention to provide an integrated marking material for fresh or hardened concrete or asphalt applications that can be stored and transported as a dry formulation.
It is a further object of the present invention to provide a dry formulation for an integrated marking material for concrete or asphalt applications that can be mixed with water on site for simple application to a road or highway.
It is a further object of the present invention to provide a dry formulation for an integrated marking material for concrete or asphalt applications that avoids the pr
MBT Holding AG
Renner Kenner Greive Bobak Taylor & Weber
Watkins III William P.
LandOfFree
Integrated marking materials does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Integrated marking materials, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Integrated marking materials will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3146165