MXPA97010367A - Pavement marker with upper coatings multip - Google Patents

Abstract

A pavement marker and a method for making a pavement marker, wherein the retroreflectivity and resistance to skidding or sliding can be controlled independently while making efficient use of the optical elements of the particles resistant to skidding or slippage. An illustrative embodiment includes two coatings (30, 32) on a base sheet (12) having first and second major surfaces (28), the first major surface having a plurality of protrusions (14) located therein, which are separated by valleys (16). A first coating (32) is selectively located on the protuberances. A first mixture of optical elements and / or particles resistant to skidding (36), is attached to, for example, partially embedded in the second coating.

Description

PAVEMENT MARKER WITH MULTIPLE UPPER COVERS FIELD OF THE INVENTION The present invention pertains to pavement markers that include optical elements and / or particles resistant to skidding or slippage. In particular, the present invention relates to pavement markers to which are selectively secured optical elements and particles resistant to skidding or sliding, in different coating layers and methods for manufacturing such pavement markers.

BACKGROUND OF THE RELATED ART Pavement markers are used on roads to represent traffic lanes and other traffic information to drivers of motor vehicles. Very often, pavement markers are retroreflective so that drivers of motor vehicles can see the markers intensely at night. Retroreflective pavement markers have the ability to return a substantial portion of incident light to the source from which the light originated. The light of the headlights of a motor vehicle is REF .: 26376 returns to the approaching vehicle to illuminate, for example, the limits of the traffic lanes for the driver of the motor vehicle. In view of the important purpose of pavement markers, researchers have continuously tried to make several improvements. Actually, the technique of pavement markers is replete with patented descriptions; see for example U.S. Patents: 5,286,682, 5,227,221, 5,194,113, 5,087,148, 4,988,555, 4,969,713, 4,490,432, 4,388,359, 4,988,541, 4,490,432, 4,388,359, and 4,117,192, all of which are incorporated herein by reference. Known retroreflective pavement markers typically include a rubber base sheet containing pigments and fillers. The optical elements and / or particles resistant to skidding or sliding are typically secured to a base sheet being embedded therein, secured thereto by a binding material or binder. Pigments and fillers are typically dispersed throughout the base sheet for several reasons, including shortening, improving durability, and providing formability. Pigments have also been placed in the bonding material to increase the visibility of the pavement markers and as a part of the retroreflective mechanism.

When the retroreflective pavement marker, may include a raised pattern of protrusions on the upper surface of the base sheet to elevate the optical elements above the water or other liquids on the road, thereby increasing the reflectivity of the pavement marker under wet conditions, see for example, U.S. Patent Nos. 5,227,221, 5,087,221, 5,087,148, 4,969,713, and 4,388,359, all of which are incorporated herein by reference. The light incident on a typical retroreflective pavement marker is retroreflected as follows. First, the incident light passes through and is refracted by the optical elements so that it collides with the pigments in the base sheet or in the bonding material. The pigments then disperse the incident light, and the optical elements redirect a portion of the scattered light back in the direction of the light source. Typical slip or slip particles do not play a role in retroreflectivity; They are arranged in retroreflective and non-retroreflective pavement markers to improve dynamic friction between the marker and a vehicle tire. The pavement markers described in US Patents 5,227,221, 4,988,555, and 4,988,541 (collectively referred to as "Hedblom patents") are all incorporated by reference, and represent advances in the art making very effective use of optical elements and / or resistant particles. when skidding or sliding This is achieved by using a base sheet with a pattern and selectively applying a bonding material to the protrusions, so that the optical elements and / or more resistant to skidding or sliding are exclusively secured to the protuberances, where they are more effective. The optical elements and / or particles resistant to skidding or sliding are substantially in front of the valleys, where they have very little contribution to the retroreflective performance or resistance to skidding or slippage of the pavement marker. By selectively securing the optical elements and particles resistant to skidding or sliding to the protrusions, less optical elements and fewer skid-resistant particles can be used, without sacrificing retroreflective performance and skid resistance. Although the pavement markers described in the Hedblom patents show good retroreflectivity and good skid resistance, and make efficient use of optical elements and skid resistant particles, it has been found that fillings in the rubber base sheet become present on the front surface of the base sheet after the pavement marker was ejected for an extended period of time. When a substantial amount of fillers is present on the front surface of the base sheet, the pavement marker shows a white or chalk-like color. The presence of the fillings in the base sheet becomes problematic when it is intended that the pavement marker present a different color than the white. When the pavement marker has a color other than white, for example, red, green, blue or black, the intended color of the pavement marker can be severely diluted by the presence of the fillers. This problem is exceptionally severe, where pavement markers are subject to intense sun exposure. In the southern locations of the United States of America, the red pavement markers have turned a pink color after being exposed to the sun for a few months. In addition, typical patterned pavement markers include closely spaced protuberances. As a result, the contact between a tire and the valleys located between the protuberances may be minimal or non-existent. Therefore, it has been considered advantageous to place the skid-resistant particles in the protuberances along with the optical elements, thereby ensuring contact between the skid-resistant particles and a tire.

A disadvantage of placing next to the optical elements and the resistant particles to the skid in the protuberances, is that the space in the protuberances is limited. As a result, the application of the skid resistant particles in the same areas of the optical elements results in a compromise between the skid resistance and the reflectivity, that is, as more optical elements are applied, there is less space to join the particles resistant to skidding to the pavement marker and vice versa. Up to a certain level, the retroreflectivity of the pavement marker is generally related to the number of optical elements located in the protuberances and the resistance to skidding is generally related to the number of particles resistant to skidding in the protuberances. As a result, reflectivity and skid resistance can not be optimized in both pavement markers in which both the optical elements and the skid-resistant particles are located in the protuberances, due to the limited space available in the protuberances.

BRIEF DESCRIPTION OF THE INVENTION The present invention provides a new pavement marker and a new method for making a pavement marker, wherein retroreflectivity and skid resistance can be controlled independently while making effective use of optical elements and skid resistant particles. An illustrative embodiment of a pavement marker including two coatings comprises a base sheet having first and second major surfaces, the first major surface having a plurality of protuberances located therein, which are separated by valleys. A first coating is attached to at least a portion of the first major surface of the base sheet, and a second coating is selectively located on the protuberances. A first mixture of optical elements and / or particles resistant to skidding will be attached, for example, partially embedded in the first coating and a second mixture of optical elements and / or skid resistant particles are attached to, for example, partially embedded in. , the second coating. An illustrative method for manufacturing a pavement marker including two coatings comprises providing a substantially flat base sheet and applying a first coating to the first major surface of the base sheet, forming a plurality of protrusions in the base sheet and the first coating, the protuberances are separated by valleys; selectively applying a second coating, and joining a second mixture of optical elements and / or skid resistant particles to the second coating, and joining a first mixture of optical elements and / or skid resistant particles to the first coating. The pavement markers according to the invention differ from known patterned pavement markers, in that a first coating is placed on the first major surface of the base sheet at least in the valleys, and a second coating is located selectively on the protuberances. Additional layers of coating may be provided as desired. By joining desired mixtures of optical elements and / or skid resistant particles to the different coatings, the optical and skid resistance properties of the pavement marker can be controlled independently. In an illustrative embodiment of the pavement marker including two coatings, a mixture comprising mainly optical elements, is attached to the second coating, which itself is selectively located on the protuberances of the pavement marker. As a result, the optical elements can be exploited effectively and efficiently to increase the retroreflectivity of the pavement marker. In a similar wayBy joining a mixture comprising mainly skid-resistant particles to the first coating, its properties are exploited more effectively to increase the skid resistance of the pavement marker. A further advantage of the present invention is that the first and second coatings effectively cover the first complete surface of the base sheet, which reduces the oxidation of the rubber base sheet due to exposure to ultraviolet (UV) light. . By covering the base sheet in this manner, the pavement markers can more effectively retain their intended color, after being exposed to the sun for extended periods of time and, therefore, are particularly advantageous for use in climates where exposure The sun is intense. The reduction of oxidation is especially useful when the pavement marker is intended to have a color other than white. In an illustrative embodiment employing two coatings, the first coating is a thermoplastic material and the second coating is a thermosetting material. By exploiting the opposite properties of these materials, the pavement markers according to the present invention can be easily produced and exhibit favorable properties to increase their adhesion to the road surface.

In an illustrative method for manufacturing a pavement marker having two coatings, a thermoplastic layer is laminated to a rubber base sheet. Lamination or embossing to form the desired protrusions in a process which ensures that the thermoplastic layer remains at least in the valleys and, potentially, on the protuberances as well. The protuberances are then covered with the thermoset material, after which a second mixture of optical elements and / or skid resistant particles are attached to the hardened material. Due to the properties of the thermoplastic, the second mixture of optical elements and / or skid resistant particles are essentially all located in the thermoset material that has not cured. The pavement marker is then heated to simultaneously cure the thermoset material and prepare the thermoplastic material to accept and retain the first mixture of optical elements and / or skid resistant particles. The optical elements and / or particles resistant to skidding in the first mixture do not bind to the protuberances for at least two reasons. The first mixture is preferably introduced after the thermoset material is at least partially cured, thereby reducing its bonding potential. Also, by introducing the second mixture of optical elements and / or skid-resistant particles when the thermoset material is recently coated (i.e., substantially uncured), the optical elements and / or skid resistant particles in the second mixture can occupy substantially all the "piece of furniture" covered with the thermoset material. As a result, when the first mixture is introduced, there may be little or no space in the thermoset material to accept the optical elements and / or particles resistant to skidding of the first mixture. Those skilled in the art will understand that the location of thermoset and thermoplastic materials can be reversed, while maintaining many of the advantages of the present invention. The thermoset material is, however, preferably limited to the protuberances, since it is typically harder than a thermoplastic, and limiting its location to the protuberances increases the flexibility of the pavement marker according to the present invention. The advantages of providing a coating that reduces oxidation on the entire first surface of the base sheet, while maintaining sufficient flexibility is particularly important in the patterns of pavement markers according to the present invention, in which the protuberances are separated to increase retroreflectivity by reducing the "blocking" or "shading" of neighboring protuberances. Such modalities, the area occupied by the valleys is substantially greater than the typical patterned pavement markers, thereby increasing the negative effects of oxidation on the valleys. In addition, the placement of the skid-resistant particles in these valleys indicates that maximizing the placement of the optical elements in the protuberances is especially useful because both properties, that is, the resistance to skidding and retroreflectivity, can be optimized without you degrade the other property. Those and other advantages of the invention are shown and described more fully in the drawings and the detailed description of this invention, where similar reference numerals are used to represent similar parts. It should be understood, however, that the drawings and description are for illustration purposes only, and should not be read in a manner that would unduly limit the scope of this invention.

BRIEF DESCRIPTION OF THE DRAWINGS In the drawings; FIGURE 1 illustrates a top view of an illustrative pavement marker 10 according to the present invention.

FIGURE 2 illustrates a cross section of pavement marker 10 of FIGURE 1, taken along line 2-2. FIGURE 3 illustrates a cross section of an alternate illustrative pavement marker, 110, in accordance with the present invention. FIGURE 4 illustrates a cross section of another alternate illustrative pavement marker, 210, in accordance with the present invention. FIGURE 5 is a flow chart describing a method for manufacturing a pavement marker in accordance with the present invention. FIGURE 6A is a simplified cross-sectional view of a base sheet / first coat laminate after embossing. FIGURE 6B is a simplified cross-sectional view of an alternate base sheet / first coat laminate after embossing. FIGURE 7 illustrates schematically a method for making a pavement marker 10 according to the present invention. The figures are idealized and are not drawn to scale.

DETAILED DESCRIPTION OF THE ILLUSTRATIVE MODALITIES In the practice of the present invention, a pavement marker is provided which makes efficient use of both the optical elements and the skid resistant particles. The pavement markers according to the present invention include a selected configuration of vertical protuberances, which rise above the upper surface of a base sheet that is applied to a road. The protuberances do not necessarily need to be of regular shape, size, or separation. However, the present invention is perhaps more easily understood and explained with reference to the embodiments described therein, in which the protuberances are formed and separated in a regular manner. A protrusion configuration is designed to minimize the shading of adjacent protuberances (in the line of sight of a conductor), separating the protrusions a little away as well as decentering them laterally (with respect to the driver's line of sight), which what is typical in many conventional pavement markers. Such configurations are more fully described in commonly assigned U.S. Patent Application Serial No. 08 / 247,050, filed May 20, 1995, entitled PATTERN MARKER WITH VERTICAL RETRORREFLECTORS, which is incorporated herein by reference. With reference to FIGURE 1, a retroreflective pavement marker 10, according to the invention, includes a base sheet 12, which has a plurality of protuberances 14 located therein. The valleys 16 separate the adjacent protuberances 14 and provide an area for placing particles resistant to skidding and for the water to reside in the event that rain falls on the pavement marker. The protuberances 14, which are raised above the valleys 16, preferably contain mainly optical elements, and being raised, allow the transmission of light to and from the pavement marker to occur without being damaged by the presence of water . As illustrated in the embodiment described in FIGURE 1, the protuberances 14 are typically arranged on the base sheet 12 in a predetermined pattern. The protuberances 14 shown in FIGURE 1, generally have a square edge defined by four side surfaces 23, 24, 25 and 26, and which meet at the top surface 27. The length of each side surface 23-26, is typically about 4 to 10 millimeters (mm), mass typically about 6 mm. Although the protrusions 14 described in FIGURE 1 have a square edge, it will be understood that the protuberances 14 can take any desired shape, including, but not limited to: circular, oval, polygonal, etc. The columns 18 of protuberances 14 are spaced apart, typically at a distance of approximately 15-35 mm, more typically at a distance of approximately 25 mm. As used herein, the columns 18 will typically be oriented substantially perpendicular to the separate direction that it is desired that the light be retroreflected, i.e. the direction from which the traffic approaches. Perpendicular to the columns 18, the adjacent rows 20 can be identified, which extend essentially parallel to the direction of the light to be retroreflected. The space between the adjacent rows 20, is typically about 4-10 mm, more preferably about 6-8 mm. In the embodiment described in FIGURE 1, the protuberances 14 located in the row 20, appear in each of two columns 18, that is, the adjacent columns 18 do not contain protuberances 14 in the same rows. This "lateral offset" between the protuberances 14 in adjacent columns 18, improves retroreflectivity, minimizing blocking or shading. It will be understood that the space of the protuberances can also be based on the height of the protuberances as measured above the valley 16 of the pavement marker 10, since height will also affect shading or blocking. Although a pattern of protuberances 14 is described in FIGURE 1, it will be understood that many other patterns that provide areas of increased valleys can be used. In particular, the adjacent columns may not be laterally off-center, where shading is a minor problem and the space between the adjacent protuberances 14 in a row may be modified as desired. Similarly, the space between adjacent columns 18 can also be increased or decreased if desired. The pattern described in FIGURE 1, in addition to minimizing shading or blocking, also provides an increased valley area 16, which can be used for skid resistant particles 36 in some embodiments, such as >; it is described below with reference to FIGURE 2. The increased valley 16 provides contact between the tire of a vehicle and any skid resistant particles 36, which are located in valley 16. The contact between a tire and the skid-resistant particles provide the desired friction to reduce skidding on the pavement marker 10. FIGURE 2 illustrates in a cross-section, a portion of a retroreflective pavement marker 10. As shown, the pavement marker 10 includes a base sheet 12 which has protrusions 14 protruding from a first main surface or front side 28, of the base sheet 12. Located between adjacent protuberances 14, there is a valley 16, also placed on the front side 28 of the base sheet 12. In an embodiment , the base sheet 12 has a total thickness of about 1 to 5 mm, more typically about 2 mm. The protuberances 14 typically have a height of about 0.5 to 3 mm, more typically about 1 mm. Pavement markers having base sheets with thicknesses and protrusion heights outside these ranges may be made in accordance with the present invention if desired. In the embodiment shown, the upper surface 27 of the protuberances 14 join with each of the lateral surfaces 23-26 in a rounded interface. Each of the side surfaces 23-26 can form an angle of about 70-72 ° with the plane of the base sheet 12, although other angles can be used if desired, based on the expected direction of the light that is going to retroreflect. As shown, the protuberances 14 are preferably, but not necessarily, formed as an integral part of the base of the base sheet 12; that is, as a single unit and not as two separate parts subsequently joined together. A first coating layer 30 is placed at least in the valley 16 between the protuberances 14, but as shown, it is also preferably placed on the protuberances 14 to form a substantially continuous layer on the front side 28 of the sheet base 12. A second coating layer 32 is selectively located on the protuberances 14 ,. so that it is substantially absent in the valleys 16. As shown in FIGURE 2, the second covering 32 can be located on all of the protuberances 14, ie, on the upper surface 27, as well as on the lateral surfaces 23-26. In the embodiment described in FIGURE 2, a plurality of mainly optical elements 34, is secured to the protrusions 14 by the second coating 32 and, because the second coating 32 is selectively located on the protuberances 14, essentially none of the elements 34 is located in the valleys 16, As indicated above, the layer of the first coating 30 is located and exposed in the valley 16. In the embodiment described in FIGURE 2, the layer of the first coating 30 is also located in the protuberances. 14, but is covered by the layer of the second coating 32, so that it is not exposed. In the valley 16, where the first coating 30 is exposed, it is used to join a plurality of mainly skid-resistant particles 36 to the base sheet 12. Selectively joining the optical elements 34 mainly to the layer of the second coating 32 and With skid-resistant particles 36 mainly at the first coating layer 30, the optical and skid resistant properties of the pavement marker 10 can be controlled independently. In the embodiment described in FIGURE 2, if additional skid resistance is desired, additional or different skid resistant particles 36 can be added without taking up the limited space in the protuberances 14. Placing the optical elements 34 mainly in the protrusions 14, the maximum number of optical elements 34 can be located there where they are most effective. As a result, the retroreflectivity of the pavement marker 10 can be increased without limiting the skid resistance of the pavement marker 10. Although the embodiment described in FIGURE 2 mainly includes optical elements 34 in the protuberances 14, and mainly skid resistant particles 36 in In the valley 16, alternate embodiments may include desired mixtures of optical elements 34 and skid resistant particles 36 on the protuberances 14 and on the valley 16. To optimize retroreflectivity and skid resistance, it may be desired to have a first mixture located on the valley 16 joined to the first coating 30 and a second mixture located on the protuberances 14 and joined to the second coating 32. In some cases, the first mixture can be substantially of skid resistant particles 36, while the second mixture can be substantially of elements 34. In other cases, mixtures may be more heterogeneous. and can still comprise different types of optical elements 34 and different types of skid resistant particles 36. Returning to FIGURE 3, a schematic cross-sectional view of an alternative embodiment of the pavement marker 110 according to the present invention is shown. invention. The pavement marker 110 varies from that described in FIGURE 2 in that the second coating layer 132 is selectively placed only on the sides of the protuberances 114. As a result, the optical elements 134 are also located only on the sides of the protuberances. 114. The skid-resistant particles 136 can then be placed on the upper surface (see reference numeral 27 in FIGURE 1) of each of the protuberances 114, as well as in the valley 116 of the pavement marker 110, increasing by therefore its skid resistant properties. FIGURE 4 discloses yet another embodiment of the pavement marker 210 according to the present invention, in which the second coating layer 232 is located on only a portion of the side of each protrusion 214. As a result, the optical elements 234 and / or skid resistant particles 236 can be selectively located in only corresponding portions of the protuberances 214. A further variation of this embodiment can be done by providing the first coating 230 in one color and the second coating 232 in a second color, for example, by means of the selection of appropriately colored pigments. The result would be that the pavement marker 210 will retroreflect the first color when it is reached from one direction and the second color when it is reached from a second direction (assuming both coatings include retroreflective elements.) This could help inform the conductors of important information, such as when traveling in the wrong direction on a one-way road.If desired, a second coating (not shown), formulated in a different color, could be provided on other portions of the protuberances. of base 12 suitable for this invention, can be formed using the known methods and materials, such as those described in U.S. Patent Nos. 4,388,359 and 4,490,432; both of which are incorporated herein by reference. The embossed rubber base sheet 12 may comprise elastomeric precursors, still uncured or curing, which therefore allows the viscoelastic deformation. Exemplary materials include acrylonitrile-butadiene polymers, wrappable urethane polymers and neoprene. Illustrative examples of other rubber materials that may be employed in the base sheet include styrene-butadiene block copolymers, chlorobutadiene natural rubber, polyacrylates, carboxyl-modified acrylonitrile-butadiene (see US Patent 4,282,281 incorporated herein by reference). The extender resins - preferably halogenated polymers such as chlorinated paraffins, but also hydrocarbon resins or polystyrenes - are preferably included, with the ingredients of the non-crosslinked elastomeric precursor, and are miscible with, or form a single phase with, the ingredients of the elastomeric precursor. The thermoplastic reinforcing polymers are preferably dispersed in the elastomeric precursor as a separate phase. Suitable thermoplastic reinforcing polymers include polyolefins, especially polyethylene, vinyl copolymers, polyethers, polyacrylates, polyurethanes, styrene-acrylonitrile copolymers and cellulose derivatives. In addition to the rubber component, the base sheet 12 also preferably includes fillers. As the term is used herein, "fillers" means an inert inorganic mineral material, typically in the form of a powder, that is contained within the interior of the base sheet. Fillers can be included in the base sheet for a number of reasons, for example, to alter the hardness, to decrease the cost, and to improve the hardness of the surface and the abrasion resistance. Examples of fillers that can be added to the base sheet include talc, mica, white pigments such as Ti02 (white pigments are designated in the Color Index as white pigments under the "PW" notation), silicates, glass beads, carbonate calcium, carbon black, asbestos, barite, fixed white (precipitated barium sulfate), slate flour, soft clays, etc. The most common fillers are Ti02, Si02, and talc. The fillers are typically added to the base sheet at about 50 to 80 weight percent, more typically at about 60 to 75 weight percent, based on the weight of the base sheet. As indicated above, the invention is also suitable for pavement markers that by day have a different color than white. As discussed in commonly assigned U.S. Patent Application Serial No. 08 / 296,677, filed on August 26, 1994, entitled PATTERNED CHALK-RESISTANT PAVEMENT MARKING, which is incorporated herein by reference. The coating materials, which are described in greater detail below, can also provide oxidation resistance, as well as serve as a means for bonding the optical elements 34 and the skid resistant particles 36 of the pavement marker 10. In general, suitable materials for the first and second coatings 30 and 32 are preferably characterized by excellent adhesion to the optical elements and / or skid resistant particles, which are typically partially embedded in the coating materials . In addition, the materials of the first coating are preferably strongly bonded to the base sheet 12 and the materials of the second coating are strongly bonded to the first coating material and / or the base sheet 12, depending on the exact construction of the marker of pavement 10. Both coating are preferably highly cohesive and resistant to environmental climate. Typically, the layer of the first coating 30 is present in the pavement marker 10 in a thickness of approximately 0.1-0.5 mm, more preferably, about 0.2 mm. The layer of the second coating 32 is present in the marker of the pavement 10 in a thickness of approximately 0.1-0.5 mm, more preferably 0.3 mm. In any case, the thickness of the coating should be sufficient to firmly join the optical elements 34 and the skid resistant particles 36 to the pavement marker 10. It will be understood that thicknesses outside these ranges can be used if desired. Optical elements 34 suitable for use in the invention include glass microspheres, (also known as retroreflective beads or beads) formed of glass materials having refractive indices of about 1.5 to about 1.9. As is well known in the art, glass microspheres of material having a refractive index of about 1.5 are less expensive and more durable than glass microspheres of a material having a refractive index of from about 1.75 to about 1.9.; however, the less expensive, durable glass microspheres may be less effective retroreflectors. The preferred microspheres have a diameter compatible with the size, shape, spacing and geometry of the protuberances present in the base sheet. Typically, 50-350 m diameter microspheres can be employed. Other factors that affect the size of the element is the number of rows of pearls desired to be available to the headlights of a vehicle. See the Hedblom patents for more detailed discussions. The optical elements 34 useful in the present invention are described in U.S. Patents 4,564,556 and 4,758,469, which are incorporated herein by reference, and are generally described as transparent solid, non-vitreous, ceramic spheroids, comprising minus a crystalline phase containing at least one metal oxide. Ceramic spheroids can also have an amorphous phase such as silica. The term non-vitreous means that the spheroids have not been derived from the fusion or mixture of raw materials capable of being carried to a liquid state at high temperatures, such as glass. The spheroids are resistant to scratching and chipping, are relatively hard (above 700 Knoop hardness) and are made to have a relatively high refractive index (ranging between 1.4 and 2.6). These optical elements may comprise zirconia-alumina-silica and zirconia-silica. Furthermore, it will be understood that other optical elements 34 such as plastic or ceramic microspheres can be used if desired and that the present invention is not limited to the use of glass optical elements. The skid resistant particles 36 can be, for example, ceramics such as quartz or aluminum oxide or a similar abrasive medium. The skid resistant particles can also include cooked ceramic spheroids, which have a high alumina content as taught in U.S. Patents 4,937,127, 5,053,253, 5,094.90'2, and 5,124,178 to Haenggi et al., Incorporated herein. as reference. The particles do not splinter on impact, as the crystalline abrasive medium such as A1203 and quartz. The skid resistant particles typically have sizes of about 300 to 800 microns. The present invention exploits the different properties of the materials used for the first and second coatings 30 and 32 to provide a method for manufacturing a pavement marker 10 according to the present invention, which can be manufactured in one step through the equipment appropriate.

In an illustrative embodiment, one of the coatings is preferably a thermoplastic material, while the other coat is a thermoset material. As a result, the thermoset material can be applied uncured and both the optical elements 34 or the skid resistant particles 36 can be applied to the uncured thermoset material without being bonded to the thermoplastic material because it is in a substantially solid state. In addition, a substantial majority of the open surface of the thermoset material can be covered by the optical elements 34 and / or the skid resistant particles 36. After the mixture of optical elements 34 and / or particles resistant to skid 36 have been applied to the thermosetting material, and can begin the curing process of the thermoset material by heating. This same heating process also serves to prepare the thermoplastic material to receive the optical elements 34 and / or skid resistant particles 36. Although a few stray particles can themselves be attached to the thermoset material if it is not completely cured at the time of application. introduction of particles in the thermoplastic material, such poor locations can be minimized by ensuring that as much as possible of the surface of the thermoset material was uncured.

As described below, the illustrative methods and resulting pavement markers provide a first coating 30, which is a thermoplastic material located on substantially all of the marker 10 and a second coating 32 which is a thermosetting material located on the protuberances 14. One reason for this preference is that, typically, thermoplastic materials are more flexible than thermoset materials. Because the spacing of the protrusions 14 results in a substantial amount of the valley 16, the first coating 30 is located on a substantial portion of the base sheet 12, the use of a thermoplastic material for that first coating 30 will generally provide a marker more flexible pavement 10, which is more capable of conforming to uneven road surfaces, and will resist better as traffic moves over pavement marker 10. Figure 5 is a flow diagram illustrating in general terms a method for manufacturing a pavement marker according to the present invention. A more detailed discussion of an illustrative method is presented later. The first stage in this process involves calendering the premix of the base sheet according to known methods. The first coating 30 (preferably a thermoplastic) can be laminated to the base sheet 12 during the calendering operation. After lamination, the base sheet 12 and the first cover 30 are embossed to form the protrusions 14 on the first surface of the pavement marker 10. Alternatively, the base sheet 12 can be formed and embossed first , after which the coating 30 can be applied, for example, laminated or coated, to the embossed base sheet 12 in a process in which the coating 30 forms the shape of the base sheet 12. Although it does not requires, it may be desirable to include one or more "tie" layers between the base sheet 12 and the first coating 30, to increase the adhesion between the base sheet and the first coating. Such tie layers are even described in U.S. Patent No. 5,194,113, which is incorporated by reference, and, as a result, will not be described here in greater detail. After the embossed laminate 11 (consisting of the base sheet 12 and the first coating 30) is formed, the second coating material (preferably a thermoset material) can be applied to the protuberances 14. The methods for cover the bumps, such as those considered of the present invention are described in, for example, U.S. Patent No. 4,988,555 to Hedblom, which is incorporated herein by reference. After the second uncured thermosetting coating is in place, the second mixture of optical elements 34 and / or skid resistant particles 36 is applied to the second coating 32. For ease of understanding, this mixture of particles is referred to as a " second "mixture" because it is applied to the second coating, although in the method described herein, the second mixture is actually applied first. In addition, for clarity in the drawings, the second mixture will consist solely of optical elements 34, while the first mixture (applied to the first coating 30) will consist only of particles resistant to skid 36. Those limitations should not be considered as limiting the scope of the invention, in which the blends can comprise any variety of particles, optical or resistant to skidding. A method for applying the optical elements 34 and / or skid resistant particles 36 are described in detail below, and additional methods for applying the optical elements, are described in, for example, U.S. Patent No. 4,988,555, and U.S. Patent Application Serial No. 08 / 296,677, filed on August 26, 1994, entitled PATTERNED CHALK-RESISTANT PAVEMENT MARKING, both of which are incorporated herein by reference. After the first mixture of optical elements 34 is provided, the process of curing the second coating 30 is then started, which joins the optical elements 34 to the second coating, and reduces the ability of the second coating to accept and retain addition particles. . Because the second coating is a thermosetting material, the curing process is carried out by the application of heat. The same heat simultaneously achieves the next step of preparing the first coating (a thermoplastic) to receive the skid resistant particles 36 by heating and softening the thermoplastic material. After the first coating 30 is sufficiently prepared, the first mixture, consisting mainly of skid resistant particles 36, in the described embodiments, can be deposited in the first coating 30, where they are joined in place. It is preferred that the second coating be sufficiently cured and / or covered by the optical elements 34, to prevent a significant number of skid resistant particles 36 from joining the second coating 32.

After the skid resistant particles 36 are in position, the curing process can be completed to completely cure the second coating 32 and complete the manufacture of the pavement marker 10. Some illustrative base sheet materials are described above. To some degree, the materials used for the base sheet 12 will influence the choice of the materials for the first coating 30. Returning to Figure 6A, a schematic cross-sectional view of the base sheet 12 and the first coating 30 are described when properly formed after embossing to form the protuberances 14. As shown, it is preferred that the first covering 30 covers the protuberances 14, as well as the valley 16 between the protuberances 14. It is essential that the areas of the valley 16 They cure, but some tolerances can be made as to whether the protrusions 14 are not covered by the first coating 30 since they can be subsequently covered by the second coating 32. Figure 6B describes a similar view of an unwanted product after the etching step. relief. As shown, the material of the first coating 30 is concentrated in the protuberances 14 and is substantially absent from the valley 16 between the protuberances 14. The reason for this occurring is a difference in viscosities between the materials used for the base sheet 12 and the first coating 30. The situation described in Figure 6B can be avoided by suitably controlling the viscosities of the base sheet 12 and the first coating 30. Some illustrative examples of thermoplastic materials useful in conjunction with the present invention can be chosen from: copolymers of ethylene acrylic acid (EAA), ethylene methacrylic acid (EMAA) copolymers, polyethylene (PE), ethylene copolymers, polypropylene (PP), ethylene-propylene-diene terpolymers (EPDM), polybutylene, ethylene-methacrylic acid-ionic crosslinked copolymer , ethylene n-butylacrylate (EnBA), ethylene vinyl acetate (EVA), ethylene ethyl acrylate copolymer (EEA), and cop Ethyl-en methyl acrylate olimer (EMA). Other thermoplastic materials suitable for securing the optical elements 34 and / or the skid resistant particles 36 to the pavement marker 10 are the vinyl-based thermoplastic resins; see U.S. Patent No. 4,117,192, incorporated herein by reference. An illustrative example of a thermosetting material useful in conjunction with the present invention is a polyurethane layer, preferably an aliphatic polyurethane.

A useful polyurethane layer can be formed by first reacting two equivalents of methylene bis (4-cyclohexyl isocyanate) (H 2 MDI) with one equivalent of polycaprolactone triol polymer (a 2-oxypanone polymer with 2-ethyl-2- (hydroxymethyl)) -1, 3 propanediol) of molecular weight of about 540 and a hydroxyl number of about 310, using dibutyltin dilaurate as a catalyst. The reaction can be carried out in ethyl-3-ethoxy propionate. NUODEX - which is believed to be a catalyst of 8-percent by weight zinc 2-ethylhexanoate, available from Huis America of New Jersey - can be added to the thermosetting blend shortly before applying the layers to the sheet of base. The inclusion of up to about 10% of 2-pentanedione in the mixture can extend the life in the mix container from about 1.5 hours to about 15 hours. Another polyurethane that may be suitable for use as a thermoset layer may include a polyurethane obtained by reacting a polycaprolactone triol polymer with an aliphatic polyisocyanate resin, such as hexamethylene diisocyanate (HDI), for example, DESMODUR N-3200 from Miles. Illustrative examples of other materials that may be suitable for use as a thermosetting layer include: epoxies, preferably aliphatic epoxies, such as hydrogenated bisphenol A epoxides, and other aliphatic epoxies such as polyethylene glycol diglycidyl ether, combination polymers based on aliphatic epoxies and diols (any of the above-mentioned epoxies would normally be used with a crosslinker such as a multi-functional aliphatic amine, carboxylic acid, anhydride acid, mercaptan or polyol, but may undergo homopolymerization as well); acrylics such as solutions coated with acrylic and methacrylic common monomer absorbers, with or without vinyl monomers, a wide variety of liquid applied, weather-stable coating systems, including, but not limited to acrylated oligomers and / or methacrylates, crosslinking system based on urea-formaldehyde and melamine-formaldehyde, polyethers, and polyaziridine / carboxylic acid systems. Some thermosetting layer materials may be somewhat effective as clear resins, but usually all would benefit from the use of appropriate UV stabilizers and / or pigmentation systems. UV stabilizers, such as UV absorbers, hindered amines, nickel chelates, hindered phenols, and aryl esters, may be added to the thermoset layer. Examples of UV stabilizers are described in Kirk-Othmer, Encyl. Chem. Tech., Pp.615-627, v. 23, (3d, Ed. 1983). Additionally, colored pigments may be added to the blend of the heat-set layer to additionally protect the underlying base sheet and to increase the color of the pavement marker (ie, match the color of the base sheet). The colored pigments can be added to the mixture of the polyurethane layer in the form of a dispersion. Useful ranges of pigment dispersion which may be included are from 10-30 parts per 25 parts of urethane prepolymer. The colored pigments are generally present in the barrier layer at a percentage of 1 to 40 based on the weight of the thermoset layer. Useful colored pigments can include those cited above for use in the base sheet, and any other colored pigments typically used for colored pavement markers, can also be used. Other suitable thermosetting materials include two-part polyurethanes formed by reacting polycaprolactone diols and triols with hexamethylene diisocyanate derivatives; epoxy-based resins such as those described in U.S. Patent Nos. 4,248,932, 3,436,359, and 3,580,887; and blocked polyurethane compositions as described in U.S. Patent No. 4,530,859. The thermoset material may also contain UV stabilizers and the colored pigments mentioned above. The material can be colored to match the color of the base sheet and the thermoplastic material. UV stabilizers and colored pigments can be incorporated into the thermosetting material as taught in the Hedblom patents, the descriptions of which are incorporated herein by reference. The retroreflective pavement markers according to the present invention can be made in accordance with the method illustrated in FIGURE 7. That method is preferably carried out continuously, by the sequential steps listed and described in conjunction with FIGURE 5 above . Those steps are broadly described schematically in FIGURE 7. The laminate 11 comprising the base sheet 12 and the first coating 30, may be provided according to known methods; see United States Patents 4,117,192 and 5,194,113, both of which are incorporated by reference. Briefly, however, an illustrative process for making base sheet 12 and first cover 30 may include the steps of providing a molding roll with an enlarged surface and an accompanying pressure roller. The base sheet 12 is fed through the laminator. Next, the layer of the first coating 30, comprising a thermoplastic material in one embodiment, is extruded by melting into the material of the base sheet 12 to form the laminate 11 as shown in FIG. 7. In an alternate embodiment, the process for forming the laminate 11 may include a suitable adhesive or another "tie-down" layer interposed between the base sheet 12 and the first layer 30, as a means to improve the bond between these two layers. The use of a tie layer is particularly advantageous in cases where the layer of the first covering 30 and the base sheet 12 comprises especially different materials. In such cases, it can be difficult to join the two layers one to the other. The choice of an appropriate tie layer having an adequate affinity for both materials (ie those of the first cover 30 and the base sheet 12), can provide an effective increase in bond between the two layers. In any case, the laminate 11 formed by the base sheet 12 and the first coating 30, is then embossed to form the desired protuberances 14, separated by the valley 16. The steps of rolling and embossing are not described in FIG. FIG. 7. Alternately (as described above with respect to FIGURE 5), the base sheet 12 can be formed and embossed before the first coating 30 is laminated to the base sheet 12. This process can avoid the above problems involved in embossing different materials in the sheet 12 and the first coating 30. The third step of the process described in FIGURE 7, involves applying the material of the second coating 32 to the protuberances 14, formed in the laminate. As described, the laminate 11 is oriented with the projections 14 projecting downwards and the second main surface or the rear side 38 oriented upwards. The protuberances 14 are brought into contact with a film 50 of the material of the second liquid coating 51, on an engraving roll 52. The engraving roll 52 receives the film 50 of the liquid material of the second coating 51, being first immersed in a reservoir 55 of the liquid material of the second coating 51. The engraving roll 52 preferably has a hard external surface (eg, of steel) to allow the liquid material of the second coating 51 to be selectively applied to the protuberances 14. A rear roll 54 it comes into contact with the rear surface 38 of the base sheet 12 to advance the laminate 11 by rotating counterclockwise in the direction of the arrow. As the laminate 11 advances, the engraving roller 52 passes through the reservoir 55 of the liquid material of the second coating 51, to form the film 50, on the engraving roller 52. A scraper blade or a slotted bar 44 can be used to size the film 50 to a desired thickness. As the rotation continues, the film 50 contacts the protrusions 14. As the protrusions 14 come into contact with the film 50, a discontinuous layer 32 of the bonding material is applied to or etched into the protuberances 14. The portions non-adherent 57 of the film 50 return to the reservoir 55 on the engraving roller 52. Several factors affect the transfer of the liquid material from the second coating 51 to the laminate 11. These factors may include • the pressure of the pressure rollers, the hardness of the engraving roller 52, the hardness of the rear roller 54, the viscosity of the liquid material of the second coating 51, the rolling speed 11, and the speed of rotation of the rear roller 54 relative to the engraving roller 52. In addition, the process described in FIGURE 7 it provides a coating of the material of the second coating 51 on the entire protrusion 14. As described in conjunction with the embodiments described in FIGURES 3 and 4, it may be desirable to apply the material 51 only on the lateral surfaces of the protuberances 14, or even only on a portion of the lateral surfaces. These variables can be affected as desired and are widely discussed in the Hedblom patents. Carrying out the fourth step of the method, the laminate 11 is reversed after the layer 32 of the material of the second coating has been applied to the protuberances 14. The second mixture of particles, Which comprises mainly optical elements 34 as discussed above, is then applied and partially embedded in the still fluid layer 32 of the material of the second coating. The optical elements 34 can be applied by a flood coating process, which results in a dense packing of the optical elements 34 in the second coating. This can be achieved by dropping the optical elements 34 from a nozzle 60 on the upper surface 28. A vibrator 58 such as a rotating rod can be placed below the laminate 11 to cause the particles in the second "mixture" (all optical elements 34 in FIG. this example), which fall inside the valley 16, bounce upwardly in the layer 32 of the material of the second coating in the protuberances 14. Alternatively, the optical elements 34 can be spread or sprayed onto the base sheet 12, so that a dense packing is avoided The spreading process can be advantageous to decrease the use of optical elements and to decrease dirt retention between the optical elements 34. After the optical elements 34 are partially embedded in the material of the second coating , the curing process of the second coating material is started to retain the optical elements 34 in a secure position in the layer 32, of the material of the second coating on the protuberances 14. As indicated above, the second preferred coating is a thermoset material, and as a result, the heat of the furnace 62 provides sufficient temperatures to begin the curing process. After leaving the oven 62, a vacuum cleaner (not shown) can be used to gather the unsecured optical elements 34 and the skid resistant particles 36 for recycling. The temperature and residence time in the furnace 62 is preferably sufficient to prepare the thermoplastic layer provided as the first coating 30 for receiving and retaining the skid resistant particles 36 within the valley 16 between the protuberances 14. In a In this process, the furnace 62 is maintained at approximately 120 ° C or more, and the speed of the network is controlled so that at a given point in the network it remains with the furnace 62 for a period of 1-5 minutes. The temperature and residence time are, of course, determined based on the curing characteristics of the second coating material 32, as well as the properties of the thermoplastic material used for the first coating 30 as described below. As a result, the temperature and dwell time will vary based on the choice of materials. Other methods for applying the optical elements 34 and / or skid resistant particles 36 to a thermosetting material can be found in U.S. Patent No. 3,451,537, incorporated herein by reference. In addition, although an oven 62 is described for use in a method according to the present invention, it will be understood that heated rolls or other methods and heat transfer apparatus may also be used to cure the thermoset material used to bond the optical elements 34 and / or skid resistant particles 36 to the pavement markers according to the present invention. A variety of such methods is described in U.S. Patent No. 5,194,113, which is incorporated by reference. In the method described in FIGURE 7, after the laminate 11 has traveled through the furnace 62, the material of the first exposed coating 30, which is located at least in the valley 16 and is possibly located on a portion of the surfaces lateral and / or upper surfaces 27 of the protuberances 14, will be able to receive and retain the "first" mixture of particles of the nozzle 70. As discussed above with respect to FIGURE 5, the first described mixture supplied from the nozzle 70 comprises only particles resistant to skidding 36, although any other particle combination can be supplied there, the exact methods used to supply particles 36, may include flood coating, spreading, spraying, etc., and the exact method will depend on many factors including particle size,. viscosity of the first coating 30, the speed of the network and others. As with the second blend of optical elements 34 described in FIGURE 7, a vacuum system can be used to remove excess particles and a hitting bar or other vibration device can be useful for uniformly distributing skid resistant particles 36, especially when it is desired to place the particles 36 on the upper surfaces 27 of the protuberances 14. If necessary complete the curing of the second coating layer 32, one or more additional furnaces 72 can be provided, to further heat the pavement marker 10. Those with skill in the art will understand that although the furnaces 62 and 72 are described as separate in FIGURE 6, they may also be provided as "zones" in a multi-zone furnace, in which case the nozzle 70 may actually be located within the furnace. It will be understood that, in place of the furnace 62 used to begin curing the second coating 32, the first coating 30 may also be softened by the use of one or more heated rollers as described in U.S. Patent No. 5,194,113. The preferred conditions of temperature and time for embedding are those which are sufficient to obtain the desired particle embedding (bead) (e.g., typically between about 40-70%). The proper adjustment of time and temperature in this process is within the skill of the technique for the materials described above. Although the above descriptions have focused on the laminates 11 in which the first covering 30 covers the entire upper surface of the base sheet 12, it will be understood that, alternatively, the first coating 30 may not be located on the surfaces of the laminations. protuberances 14. Methods for applying the first coating 30 in the valley 16 and not in the protuberances 14 will be known to those skilled in the art. They may include displacement of the first coating 30 of the protuberances 14 during embossing or simply laminating a first discontinuous coating 30, which includes gaps in the appropriate pattern for the protuberances 14. In addition, although the above descriptions have focused on the use of Thermosetting and thermoplastic materials, in combination for the multiple coatings used in the pavement markers according to the present invention, it will be understood that many different combinations of materials can be used. An alternate variation in the paving materials and the methods for making them may include the use of two layers of a thermoset material for the first and second coatings 30 and 32. In such a variation, the coatings could be applied sequentially, and loaded with a desired particle (optical or skid resistant) and cure. In other words, the first coat layer would be applied and loaded with skid resistant particles after which it would be at least partially cured. After that, the layer of the second coating could be applied, loaded with optical elements and then a final curing process could be carried out, which would completely cure both thermoset coatings. A. The potential disadvantage of this variation is that thermosetting materials are typically, harder than thermoplastics, and as a result, can provide a less plastic pavement marker, which may not adhere to the road as well as a pavement marker more elastic. Another variation may include the use of two thermoplastic layers, each having different properties, such that its viscosity could be controlled to allow placement of the skid resistant particles in an area where a first thermoplastic material is located. Following this, the temperature of the pavement marker could be raised further, allowing placement of the optical elements in desired areas where the second thermoplastic (highest temperature) was located. In order to avoid the waste of the optical elements, it would be desirable to ensure the complete covering of the layer of the first thermoplastic with the skid resistant particles, thereby avoiding the joining of the optical elements to the first thermoplastic. Still other variations may involve the use of moisture curing, UV curing, two-part reaction systems, curing systems involving a catalyst and other variations. Furthermore, although the illustrative examples described in detail above are based on the different properties of the covering materials in relation to thermal energy, in some cases, it may be advantageous to provide coating materials in the same pavement marker, which cure with based on different properties, for example, a UV curable resin in combination with a thermosetting or thermoplastic material, moisture curable materials in combination with a resin or UV curable and a thermoplastic, etc. Those with skill in the art will know the different combinations. The following example illustrates the features, advantages, and other details of the invention. It should be expressly understood, however, that while the example serves this purpose, the particular ingredients and amounts used, as well as other conditions and details, are not constructed in a manner that would unduly limit the scope of this invention.

EXAMPLE Preparation of the Components To form a white base sheet material, the ingredients of Table 1 were mixed in an internal Banbury mixer, where they reached an internal temperature of about 150 ° C. The material was then cooled in a rubber mill and calendered on a sheet of approximately 1.4 mm in thickness.

A urethane prepolymer was made by reacting two equivalents of methylene bis (4-cyclohexyl isocyanate (H.zMDI) with one equivalent of a polycaprolactone triol (ie, a polymer of 2-oxypanone with 2-ethyl-2- (hydroxymethyl) 1, 3-propanediol) of molecular weight of about 540 and a hydroxyl number of about 310 using dibutyltin dilaurate as a catalyst The reaction was carried out in ethyl-3-ethoxy propionate. The polymer was further diluted with 2,4-pentanedione to aid in the life stability in the container The final solution of the prepolymer containing about 50 weight percent of the urethane prepolymer, and 10 weight percent of 2,4 To these 100 grams of this solution, 21.4 grams of Fine Pearl pigment purchased from The Mearl Coporation or Briarcliff Manor, New York was added.A thermoplastic coating was prepared by extruding a pre-colored resin purchased from PMS Consolidated of Elk Grove Village, Illinois. The pre-colored resin consists of 3.8 percent White Pigment # 6, 13.4 percent Yellow Pigment # 191, and 82.8 percent Nucrel 699 (an EMA copolymer available from E. I. Dupont de Nemours, Wilmington, Delaware). The pre-colored resin was extruded to a thickness of approximately 0.1 mm. The previously prepared thermoplastic coating was laminated to the rubber base sheet. This laminate was then heated to about 135 ° C and embossed to produce a base sheet with a pattern with transverse protuberances measuring approximately 1.3 mm high and 13 mm wide, with a valley spacing of approximately 13 mm. Visually, it was evident that a substantial amount of thermoplastic coating remained in the valley sections of the patterned material. The pigmented polyurethane resin was coated in a release coating using a slotted bar coating fitted to a bar gap of approximately 0.75 mm. The patterned base sheet with the first coating was inverted and the raised protuberances were pressed into the liquid polyurethane resin. The base sheet was then peeled off from the polyurethane and ceramic beads were sprayed with a refractive index of 1.93 and the standard side of the base sheet. After the beads were sprayed, the back of the sample was vibrated to remove excess pearls from the valleys. Then the sample was placed in an oven at approximately 120 ° C for 5 minutes, to begin curing the polyurethane, and to start softening the thermoplastic coating. The sample was then removed from the kiln and skid resistant particles, ceramic, were scattered on top of the product. The sample was returned to an oven at approximately 150 ° C for ten minutes and then removed. The finished sample was inspected visually. The material, when illuminated with a flash light, reflected the white brilliantly. The polyurethane coating remained nominally 99 percent free of ceramic anti-skid particles, while the valleys remained nominally 100 percent free of ceramic beads. The valleys of the product will remain yellow when observed in daylight. This invention may take several modifications and alterations without departing from the scope thereof. Accordingly, it is to be understood that this invention is not limited to that described above, but must be controlled by the limitations set forth in the following claims and any equivalents thereof. It is noted that in relation to this date, the best method known to the applicant to carry out the aforementioned invention, is that which is clear from the present description of the invention. Having described the invention as above, the contents of the following are claimed as property:

Claims (31)

1. A pavement marker characterized in that it comprises: (a) a base sheet having first and second major surfaces, the first main surface has a plurality of protuberances located therein, the protuberances are separated by a valley; (b) a first coating attached to the first main surface of the base sheet; (c) a second coating located selectively on the protuberances, so that it is substantially absent from the valley; and (d) a first mixture of optical elements and / or skid resistant particles partially embedded in the first coating; and (e) a second mixture of optical elements and / or skid resistant particles partially embedded in the second coating.

2. The pavement marker according to claim 1, characterized in that the first mixture is substantially free of optical elements.

3. The pavement marker according to claim 1, characterized in that the second mixture is substantially free of particles resistant to skidding or slippage.

4. The pavement marker according to claim 1, characterized in that each of the plurality of protuberances comprises an upper surface and a lateral surface that connect the upper surface to the valleys, and furthermore where the second covering substantially covers all surfaces upper and lateral of each of the plurality of protuberances.

5. The pavement marker according to claim 1, characterized in that each of the plurality of protuberances comprises an upper surface and a lateral surface that connects the upper surface with the valleys, in addition, wherein the second coating substantially covers the entire surface lateral of each of the plurality of protuberances, and still further where the second coating is substantially absent from the upper surface of each of the plurality of protuberances.

6. The pavement marker according to claim 1, characterized in that each of the plurality of protuberances comprises an upper surface and a lateral surface connecting the upper surface with the valleys, and wherein in addition the second coating substantially covers only a portion of the area of the lateral surface of each of the plurality of protuberances, wherein the second coating is visible from a first direction and is not visible from a direction opposite to the first direction.

7. The pavement marker according to claim 6, characterized in that the first coating exhibits a first color and the second coating exhibits a second color.

8. The pavement marker according to claim 7, characterized in that the first and second mixtures each comprise retroreflective optical elements, and wherein in addition the pavement marker retroreflects the first color in the first direction and the second color in the second direction.

9. The pavement marker according to claim 1, characterized in that the first coating forms a substantially continuous layer on the first surface of the base sheet.

10. The pavement marker according to claim 1, characterized in that the first coating is a thermoplastic.

11. The pavement marker according to claim 10, characterized in that the first coating is selected from the group consisting of copolymers of ethylene acrylic acid (EAA), ethylene methacrylic acid copolymers (EMAA), polyethylene (PE), ethylene copolymers, polypropylene (PP), ethylene-propylene-diene terpolymers (EPDM), polybutylene, ionically crosslinked ethylene methacrylic acid copolymer, ethylene n-butyl acrylate (EnBA), ethylene vinyl acetate (EVA), ethylene ethyl acrylate copolymer (EEA) , and ethylene methyl acrylate copolymer (EMA).

12. The pavement marker according to claim 10, characterized in that the second coating is a thermoset material.

13. The material of the pavement marker according to claim 12, characterized in that the thermoset material is a urethane.

14. The pavement marker according to claim 13, characterized in that the urethane is an aliphatic polyurethane.

15. The pavement marker according to claim 11, characterized in that the polyurethane is formed by reacting a polycaprolactone triol polymer with an aliphatic polyisocyanate resin.

16. The pavement marker according to claim 1, characterized in that the second coating is selected from the group consisting of polyurethanes, epoxies, acrylics, acrylated or methacrylated oligomers, crosslinking systems based on urea-formaldehyde and melamine-formaldehyde, polyesters, polyaziridine / carboxylic acid systems, and combinations thereof.

17. The pavement marker according to claim 1, characterized in that at least one of the first and second coatings contains pigments, UV stabilizers, or combinations thereof.

18. A pavement marker characterized in that it comprises: (a) a base sheet having first and second major surfaces, the first main surface has a plurality of protuberances located therein, the protuberances are separated by a valley; (b) a first coating bonded to the first main surface of the base sheet, the first coating comprising a thermoplastic material; (c) a second coating located selectively on the protuberances, so that it is substantially absent from the valley, the second coating comprises a thermo-fix material; and (d) a first mixture of optical elements and / or skid-resistant particles partially embedded in the first coating, the first mixture comprising at least a majority of particles resistant to skidding or sliding; and (e) a second mixture of optical elements and / or particles resistant to skidding or sliding, partially embedded in the second coating, the second mixture comprises at least a majority of optical elements.

19. A method for manufacturing a pavement marker, characterized in that it comprises the steps of: a) providing a continuous, polymeric, elastic network base sheet; b) providing a first coating on a first surface of the base sheet; c) forming a plurality of protuberances on the first surface of the base sheet and the first coating, the plurality of protuberances are separated by a valley; d) selectively applying a second coating to the protuberances; e) selectively joining a first mixture of optical elements and / or skid resistant particles to the first coating; and f) selectively joining a second mixture of optical elements and / or skid resistant particles to the second coating.

20. The method according to claim 19, characterized in that the step of selectively joining a first mixture of optical elements and / or skid resistant particles to the first coating comprises joining a first mixture that is substantially free of optical elements.

21. The method according to claim 19, characterized in that the step of selectively joining a second mixture of optical elements and / or skid resistant particles to the second coating comprises joining a second mixture that is substantially free of skid resistant particles.

22. The method according to claim 19, characterized in that the step of forming the plurality of protuberances further comprises forming an upper surface and a lateral surface connecting the upper surface with the valley, and wherein further the step of applying a second coating comprises further covering substantially all of the top and side surfaces of each of the plurality of protuberances.

23. The method in accordance with the claim 19, characterized in that the step of forming the plurality of protuberances further comprises forming an upper surface and a lateral surface connecting the upper surface with the valley, and wherein further the step of applying a second coating further comprises covering substantially the entire area of the lateral surface of each of the plurality of protuberances, and still still where the step of applying the second coating further comprises preventing the second covering from covering the upper surface of each of the plurality of protuberances.

2 . The method according to claim 19, characterized in that the step of forming the plurality of protuberances further comprises forming an upper surface and a lateral surface connecting the upper surface with the valley, and wherein further the step of applying a second coating comprises further covering only a portion of the area of the lateral surface of each of the plurality of protuberances, wherein the second coating is visible from a first direction and not visible from a direction opposite to the first direction,

25. The method according to claim 19, characterized in that the step of providing a first coating comprises providing a first thermoplastic coating.

26. The method according to claim 25, characterized in that the first coating is selected from the group consisting of copolymers of ethylene acrylic acid (EAA), copolymers of ethylene methacrylic acid (EMAA), polyethylene (PE), ethylene copolymers, polypropylene ( PP), ethylene-propylene-diene terpolymers (EPDM), polybutylene, copolymer of ionically crosslinked ethylene methacrylic acid, ethylene n-butyl acrylate (EnBA), ethylene vinyl acetate (EVA), ethylene ethyl acrylate copolymer (EEA), and ethylene methyl acrylate copolymer (EMA).

27. The method in accordance with the claim 25, characterized in that the step of providing a second coating comprises providing a second thermofix coating.

28. The method in accordance with the claim 27, characterized - because the thermoset material is a urethane.

29. The pavement marker according to claim 27, characterized in that the urethane is an aliphatic polyurethane.

30. The method according to claim 29, characterized in that the polyurethane is formed by reacting a polycaprolactone triol polymer with an aliphatic polyisocyanate resin.

31. The method according to claim 27, characterized in that the second thermofix coating is selected from the group consisting of polyurethanes, epoxies, acrylics, acrylated or methacrylated oligomers, crosslinking systems based on urea-formaldehyde and melamine-formaldehyde, polyesters, polyaziridine / carboxylic acid and combinations thereof.