Reflective pavement marker

A reflective pavement marker having integrally molded one-piece structural body with multiple hollow cavities that are open only at the top reflective faces of the marker, two arcuate sides and integrally sealed planar base surface with textures and discontinuous grooves. This marker provides a device to enhance agglutination to the roadway, improve resistance to flexural stresses due to automobiles impact forces; this is accomplished by maximizing the base surface area for adhesive wetting parameter. The reflective plates are welded on wedge like tops of the partition walls separating hollow cavities from each other. The body can be made of various recycled or virgin structural plastics with high impact resistance and UV stability.

BACKGROUND OF THE INVENTION
 1. Field of the Invention
 This invention relates to reflective roadway markers that are used for
 traffic lane delineation, in particular, to markers with enhanced
 reflectivity, impact resistant and low cost.
 2. Related Art Roadway markers are adhered to pavements along centerlines,
 edge lines, lane dividers or guardrail delineators. Other roadway markers
 are used as temporary lane dividers in temporary constructions, detours or
 prior to permanent marking of newly paved roadways. Since 1965, the most
 commonly used reflective roadway markers are based on Heenan U.S. Pat. No.
 3,332,327 or Balint U.S. Pat. No. 3,409,344. Typically, this type of
 markers are produced in a process consisting of four to five steps: First,
 injection molding of a thermoplastic shell, either integrally molded with
 the reflective face, or the reflective faces welded on a corresponding
 open recesses within the shell. The reflective face, having 350 or more
 cube corner reflective elements on each reflective face of the shell.
 Secondly, either the cube corner reflective elements within a shell or the
 entire inside surface of the shell coated with a reflective sealer by a
 process known as vacuum metalizing. This metallic sealer needed to seal
 the cube corner reflective elements so they retain part of their
 reflectivity prior to the next step, of filling the shell with a
 thermosetting resinous material, such as epoxy or polyurethane.
 This resinous filler material encapsulate the metalized cube corner
 reflective elements and give the marker the structural body. Finally, a
 layer of relatively course sand or glass beads dispersed over the top
 surface of the filler material prior to solidification of the filler
 material.
 Part of the sand particles will remain partially protruding above this
 planar surface of the marker base, thereby increase the adhesive wetting
 parameter of the base surface. This will improve adhesion to substrate,
 regardless of the type of adhesive used. This type of markers worked well
 for six or seven months, however, due to poor abrasion and impact
 resistant of the thermoplastic shell, nearly 60% of the reflectivity is
 lost thereafter, Also, since the coefficient of thermal expansion of the
 shell material and the resinous filler material vary, this causes pealing
 of the reflective face or the shell from the resinous body, thereby losing
 reflectivity. Several attempt were made to improve abrasion resistant of
 the reflective face. One was the thin layer of glass, in U.S. Pat. No.
 4,340,319, Another attempt was the use of polymeric coating of the
 reflective face, as described in U.S. Pat. No. 4,753,548 (Forrer). These
 abrasion resistant coating proving to be expensive and tend to reduce
 reflectivity. Other major development in the pavement marker art have been
 made in the attempt to eliminate the use of the metalized sealer for the
 cube corner reflective elements. This has been achieved by dividing the
 inside surface of the reflective face into reflective cells, each cell
 will have several cube corner reflective elements, the cells isolated from
 each other by partition and load carrying walls. The entire reflective
 face welded to corresponding recesses within a hollowed or solid body.
 This method is disclosed in U.S. Pat. Nos. 4,227,772 (Heenan); 4,232,979;
 and 4,340,319 (Johnson et al); 4,498,733 (Flanagan). These markers proved
 to be superior in reflectivity, however, lack of enough adhesive wetting
 parameter lead to poor adhesion to roadways, hence caused short life cycle
 for this type of markers. This applicant successfully developed two
 markers with non-metallized multi-cell reflective roadway. One roadway
 marker utilizes raised rhombic shaped abrasion reducing and load
 transferring raised ridges, which act to intercede abrasion elements and
 impact load, the shell filled with impact resistant epoxy. The marker body
 having a base with large wetting parameter for shear and flexural
 strength, as disclosed in U.S. Pat. No. 4,726,706.
 The second roadway marker of this applicant, U.S. Pat. No. 5,927,897
 developed a mean to increase the abrasion resistant of the reflective face
 by coating the reflective face with diamond-like film and by having
 holding pins extended beyond the partition walls into the body, the
 holding pins sealed by the filler material; this works very effectively,
 providing structural strength and maximum adhesive wetting parameter. The
 entire above reflective pavement markers are incorporated herein by
 reference in their entireties. Applicant present goal to have a roadway
 marker having: high reflectivity, enhance structural body, abrasion
 resistant, low cost, marker base area with maximum wetting parameter and
 very simple yet consistent process to manufacture.
 SUMMARY OF THE INVENTION
 This invention provide a novel raised pavement marker that comprises a
 monolithically injected body with hollow cavities, said hollow cavities
 with open ends at the reflective faces. At least one reflective face
 having insert plate with multiple cube corner reflective elements welded
 on it thereby forming air gaps beneath the reflective elements, said body
 having a base with large adhesive wetting parameter for better adhesion to
 the pavement and higher resistance to flexural stresses.
 The primary object of this invention is to eliminate the multi steps
 process in prior arts for making reflective and non-reflective pavement
 markers while retaining maximum base surface area. Another objective of
 this invention is to provide a raised roadway marker made of high impact
 and abrasion resistant material and low cost. The present invention
 further provide a method of making one piece body for raised roadway
 markers of any desirable shape and configuration having light weight, such
 as a marker with truncated body or one piece marker with a body having two
 rumble portions integrally made with two reflective faces and scalloped
 recess in-between having planar textured base.
 In accordance with still further aspect of this invention, the marker can
 be made with one or two reflective faces, this will cost considerably less
 to install to the roadway, or two multi colored parts can be welded
 together, each with one reflective face opposite the other.

DETAIL DESCRIPTION OF PREFERRED EMBODIMENTS
 Durable, cost effective and simplified production method for reflective and
 non-reflective roadway markers with maximum resistance flexural stresses
 can be achieved by having a large wetting parameter surface within the
 marker base area and producing a lightweight marker body integrally, in
 one step, from one of various available structural polymers. The marker
 body can be integrally formed in such a way as to reduce excessive
 material loss while retaining structural strength and optimum adhesive
 wetting area for the base surface. This invention satisfies the above
 conditions.
 Referring to FlGS. 1 to 6, which represent one of the preferred embodiments
 of the marker designated by the number 25 which comprises a one piece
 structural body 30 which includes multiple, hollow cavities 31c and at
 least one reflective plate attachment 40. Structural body 30 integrally
 having two inclined planar faces 31 for reflective plate attachment 40,
 two arcuate sides 34, a top portion 33 and sealed planar base surface 36
 that includes multiple, textured, arcuate grooves 36a. The inclined faces
 31, each having a planar surface 31a and a recessed portion 31b where a
 reflective plate 40 can be welded or agglutinated. Recessed portion 31b is
 where the wedge shaped top surfaces of the hollow cavity walls 31d are
 located. Hollow cavities 31c, each having centerline near perpendicular to
 the inclined planar faces 31. FIG. 4b shows a section view of a hollow
 cavity 31c showing wedge shaped top surfaces 31e of cavity walls 31d, each
 wall 31d forming an angle, preferably about 2 to 5 degrees with respect to
 the center line of said hollow cavity. Hollow cavities 31c having a depth
 that can be terminated about 0.10 to 0.15 inch above the sealed outside
 planar base surface 36, which has an extended lip 35. This depth for
 hollow cavities 31c allows body 30 to retain a solid base surface, without
 any opening for said hollow cavities. The thickness of hollow cavity walls
 31d at the lower end of wedge shaped top surface 31e is about 0.07 to 0.20
 inch at the planar recess portion 31b of the inclined planar face 31.
 These relatively thick, walls 31d,with the wedge shaped top surfaces 31e
 will significantly improve the impact resistance of body 30 while maximize
 the air gap areas beneath each cell shaped remains of the inside surfaces
 of reflective plate attachment 40.
 The inclined planar faces 31 form an acute angle with respect to the planar
 base surface 36, said acute angle, preferably having a value of about 28
 to 30 degrees. The reflective plate attachment 40 is welded to the wedge
 shaved top surfaces 31e of hollow cavity walls 31d, fusing a thin portion
 of the inside of reflective plate attachment 40, thereby forming a cell
 like reflective segments within the inside surface of plate 40. Each of
 said cells having multiple cube-corner reflective elements 41b freely open
 within each corresponding hollow cavity 31c. The air gap formed beneath
 the cube corner reflective elements within each hollow cavity 31c, allows
 maximum reflectivity out the need for metalizing the reflective elements.
 The outside surface of the reflective plate attachment 40 will have
 corresponding cell like planar reflective areas 41, need having similar
 shaves as the open ends of hollow cavities 31c bellow them. Preferably,
 the outside cell like planar areas 41 will be recessed about 0.001 to
 0.010 inch bellow the planar surface of the reflective plate attachment
 40, defining ridge like walls 42. Several shapes or sizes of hollow cavity
 31c can be selected for marker body 30, hence forming corresponding shaped
 cell like planar reflective areas 41 for the reflective plate 40.
 The following U.S. Patents provides suitable reflective plate or cube
 corner reflective element design. U.S. Pat. No. 3,712,706 to Stamm, U,S.
 Pat. No. 4,208,090 to Heenan, U.S. Pat. No. 4,232,919 to Johnson, U.S.
 Pat. No. 4,498,733 to Flanagan and U.S. Pat. No. 4,726,706 to Attar, all
 of which are incorporated herein by reference in their entireties.
 Reflective plate 40 can be coated for abrasion resistance, using suitable
 method of vapor deposited, diamond-like carbon film or silicon dioxide
 film. Pavement marker body 30 can have any commonly used size or shape for
 the base area 36. Preferably, the base are will have a width of about 4.0
 to 5.0 inch and the depth to be about 2.0 to 4.0 inch and the marker body
 height can be about 0.50 to 0.70 inch.
 Several recycled or virgin polymeric material are available and suitable
 for the production of marker body 30. Pigmented and inert filled thermo
 set or thermoplastic material can also be used to form marker body 30.
 Preferably, a comparable polymer is used to allow the sonic welding of two
 parts, the reflective plate means and the marker body 30.
 The polymer material used to make the reflective plates 40, normally is
 transparent acrylic or polycarbonate thermoplastic.
 Referring to FIGS. 7 through 11, there is shown an alternative embodiment
 of a roadway marker 5 having a body 10 integrally formed from any desired
 structural polymer, said marker body 10 having two hump portions 15, each
 integrally having a concave-curve-shaped reflective face 11 with curved
 surface 11a, open ends of hollow cavities 11c and small recesses 11e. The
 two hump portions 15 are integrally connected by a scalloped,
 recessed-portion 16. The marker body also having two arcuate sides 18 and
 a sealed planar base surface 12 having a textured and grooved surface 12a.
 Hollow cavities 11c, each having a wedge shaped top surface 11b slightly
 recessed bellow the curved surface 11a and inwardly tapered partition
 walls 11d. Hollow cavities 11c have closed ends that terminate about 0.10
 to 0.15 inch above the sealed outside planar base surface 12, The
 centerline of each hollow cavity 11c makes an angle of about 28 to 32
 degrees with respect to the planar base surface 12. Reflective plate 20
 having multiple reflective cells 20a, said cells interconnected with thin
 ties 20b. Plate 20 can be welded or agglutinated to the wedge shaped top
 surfaces 11b. Each individual reflective cell 20a tightly welded on to the
 corresponding wedge shape top surfaces 11b. Reflective cells 20a, each
 having an outside planar surface that will be positioned slightly bellow
 the curved surface 11a and having an inside surface with cube corner
 reflective elements sealed within an air gap inside of each corresponding
 hollow cavities 11c. Reflective plate 20 can be coated with abrasion
 resistant diamond-like carbon film, or silicone dioxide film, to enhance
 durability.
 FIGS. 12 through 16 illustrate yet another embodiment of reflective or
 non-reflective roadway markers, in accordance to the present invention.
 Marker 50 has an integrally made body 40 having a round spherical shaped
 top surface 41 with a round and slightly recessed center portion 42, said
 center portion 42 is divided into multiple hollow cavities 42a by
 partition and load carrying walls 42b. Walls 42b are tapered inward,
 forming 3 to 5 degrees angle with respect to the centerline of each hollow
 cavity 42a. Hollow cavities 42a terminate about 0.10 inch above the sealed
 outside planar base surface 45 with raised pens 45a, said raised pens 45a
 protrude less than 0.06 inch beyond the sealed planar base surface 45.
 When cap portion 46a is attached to body 40, a non-reflective marker 50 is
 formed. Cap portion 46a has thickness and contour correspond to the
 recessed center portion 42 of body 40. Cap portion 46a having an outside
 surface with raised ridges 43. FIG. 12A shows cap portion 46. Cap portion
 46 having an outside spherical surface 44 integrally built with raised
 ridges 43 and multiple of reflective cells 47, each cell having a planar
 outside surface and multiple cube corner reflective elements on the inside
 of said cells 47. The inside surface of cap portion 46 can be integrally
 textured with either small spherical shaped surfaces, wedged ridges, cube
 corner shaped surface or any combination of such texturing surface for
 added brightness and welding parameter. When cap portion 46 to be used,
 the entire shape and size of the hollow cavities 42a have to be formed to
 correspond to the size and shape to cells 47. Reflective cells 47 having
 the outside planar surface positioned about 28 to 30 degrees with respect
 to the planar base surface 45. Each reflective cell also forms an angle
 with respect to adjacent cell, said angle to have a value of not more than
 30 degrees. Each cell 47 welded directly on the vertex of wedge shaped top
 surfaces of hollow cavity walls 42b, thereby forming air gap directly
 beneath the cube corner reflective elements within each cell. Cap portion
 46 can be made of impact resistant and transparent polymeric material.
 Such polymeric materials are available either as a recycled or virgin.
 When color reflectors are desired, a transparent pigment will be added to
 the polymer.
 Marker 50a is another preferred embodiment of a non-reflective marker based
 on the present invention. Marker 50a can be made from recycled or virgin
 plastics such as ABS, Polypropylene, engineered plastic or any suitable
 high strength polymer. Engineered plastic is commonly referred to as
 thermosetting or thermoplastic polymers with various proportions of fiber
 reinforcement and/or inert materials added. Several compositions of these
 types of polymers are available and readily marketed, either as a recycled
 or virgin polymer. Marker 50a having a one-piece body 40a with a sealed
 spherical top surface 41a, said body 40a including multiple, hollow
 cavities 45b, each with an open end at a recessed part 45c of planar base
 surface 45a. Each hollow cavity 45b ends approximately 0.10-inch bellow
 the outside spherical surface 41a. A planar cap portion 52 can be welded
 to the recessed part 45c of the planar base surface 45a where the open
 ends of hollow cavities 45b are located. These types of reflective and
 non-reflective markers can effectively be used to replace the highly
 brittle ceramic markers, because it can retain surface brightness due to
 having minimum contact to tire surfaces, maximum base adhesive wetting
 parameter and lower production cost and shorter production cycle due to
 the multiple hollow cavities within the marker's body. Markers 50 and 50a
 can be coated with abrasion resistant vapor deposited diamond like film or
 silicon dioxide film for added surface enhancement and durability.
 Another preferred embodiment is roadway marker 60, as illustrated in FIGS.
 18 through 22. Marker 60 is ideally suited for use having two multi
 colored reflective sides or a one-color marker. Marker 60 formed having
 two parts 61 connected with a tear-able thin wedge 66a. The two parts 61
 can be welded or agglutinated at the backside 67.
 Each part 61 integrally comprises a planar top surface 66, a sealed planar
 base surface 65 with textured grooves 65a, two multi angled sides 64, an
 inclined planar face 62 and backside 67 vertical with respect to planar
 base surface 65, said backside including hollow cavities 69.
 The inclined planar face 62 includes a planar surface 62a and a recessed
 portion 62b. Recessed portion 62b having the open ends of hollow cavities
 68 and the wedge shaped top surfaces 63a of hollow cavity walls 63 that
 separate said hollow cavities from each other. The planar face 62 is
 preferably inclined about 28 to 30 degrees with respect to the sealed
 planar base surface 65. A reflective plate 70 which has a corresponding
 size and shape of the recessed portion 62b is either welded or
 agglutinated to the wedge shaped top surface 63a, thereby retaining cell
 like inside areas of the reflective plate with cube corner reflective
 elements, tightly within an air gap, inside each corresponding hollow
 cavity 68. Hollow cavities 68 are formed having a centerline near
 perpendicular to planar face 62 and a depth that terminates about 0.10
 inch above the planar base surface 65.
 Hollow cavity walls 63 form an inward angle equal or less than 5 degrees
 with respect to each centerline of the corresponding hollow cavity.
 Another form of hollow cavities 69 open within the backside 67, said
 cavities 69 can be of any eject able shape. Hollow cavities 69 are used to
 minimize any wasted polymeric material used to make part 61 without
 hampering the structural integrity of said part 61. Part 61 can be made of
 various recycled or virgin polymeric materials with the desired color
 added. Reflective plate 70 can have either planar outside surface or
 slightly recessed cell like planar surfaces corresponding to the shapes of
 the opening of the hollow cavities 68.
 The inside surface of reflective plate 70 is formed with multiple
 cube-corner reflective elements. The inside of reflective plate 70 is
 sonically welded to the wedge shaped top surface 63a of hollow cavity
 walls 63. Hence cell-like areas formed on the inside surface of reflective
 plate 70. Each cell can retain multiple of the cube-corner reflective
 elements within a corresponding hollow cavity 68.
 Either two reflective lenses can be sonically welded to each recessed side,
 or one blank plate can be welded to one side and reflective plate on the
 opposite.
 The present descriptions are considered to be few of the preferred
 embodiments of this invention. It is understood that various changes or
 modification can be made within the scope of the appended claims all such
 modification fall within the true spirit and scope of the invention.
 Therefore, the invention can be practiced otherwise than as specifically
 described herein.