US3499371A

US3499371A - Markers

Info

Publication number: US3499371A
Application number: US600225A
Authority: US
Inventors: Nelson Jonnes; Robert C Vanstrum
Original assignee: Minnesota Mining and Manufacturing Co
Current assignee: 3M Co
Priority date: 1966-12-08
Filing date: 1966-12-08
Publication date: 1970-03-10
Anticipated expiration: 1987-03-10

Description

March 10, 1970 JONNES ETAL 3,499,371

MARKERS Filed Dec. 8, 1966 INVENTOR.

M150 Ja/wvss fioanw-cflwsmm United States Patent 3,499,371 MARKERS Nelson Jonnes, Stillwater, and Robert C. Vanstrum, White Bear Lake, Minn., assignors to Minnesota Mining and Manufacturing Company, St. Paul, Minn., a corporation of Delaware Filed Dec. 8, 1966, Ser. No. 600,225

Int. Cl. E01f 9/00 US. Cl. 94-15 8 Claims ABSTRACT OF THE DISCLOSURE Reflective and reflex-reflective traffic markers especially adapted for use on pavement surfaces to delineate traffic lanes, center lines and the like are disclosed, the markers comprising a base member for attachment to a pavement and having a channel formed in its upper surface for receiving a horizontally reflex-reflecting marker.

The present invention relates to new and useful reflective and reflex-reflective traffic markers especially adapted for use on pavement surfaces to delineate traffic lanes, center lines and the like.

Delineation of pavement surfaces to mark traffic lanes, center lines, etc. has long been accomplished by the use of reflex-reflecting material, usually small glass beads of about 1.5 refractive index, partially embedded in a lightreflecting pigmented paint-like film. Such traffic markings have performed quite well in clear weather. However, when such markings are covered with a film of water during inclement weather, their reflex-reflecting ability is seriously impaired. Continued vehicular abrasion of the glass beads tends to flatten their upper surfaces, thus tending to impair their reflex-reflecting ability even under dry conditions.

Prior workers have attempted to overcome the aforenoted difliculties encountered with the beads-on-paint structures. One such attempt is illu trated in United States Patent No. 3,240,132, which is directed to a three-dimensional traffic marker having two zones, one for daytime reflection and the other utilizing glass beads for nighttime reflex-reflection of incident light. A problem encountered in combination structures has been that of providing sufficient nighttime reflex-reflective qualities While retaining sufiicient diffuse daytime reflection since glass beads to be effective must occupy a major portion of the marker surface, thereby graying-out the diffuse daytime reflectivity of the marker.

The present invention provides simply configured traffic markers which exhibit a higher intensity reflex-reflection of light under dry condition on pavement surfaces than the beads-on-paint constructions heretofore used as well as a brilliant high intensity reflex-reflection of light under wet conditions. In addition, the markers are visible as attractively colored objects during daylight to provide daytime traffic delineation.

The present invention utilizes refractive high index transparent glass beads for pavement marking purposes, while at the same time protecting such beads from the abrasive action of traffic passing thereover. Although high index heads have been known for some time, they have been sparingly used in traflic marking applications since they are significantly less wear resistant to traffic than the lower index beads. Traffic markings of the beads-onpaint type and even of the type disclosed in US. Patent No. 3,240,122 have, therefore, utilized relatively low refractive index glass beads, typically on the order of 1.5.

The invention will be described by reference to a drawing, made a part hereof, in which:

3,499,371 Patented Mar. 10, 1970 FIGURE 1 is a top plan view, partly broken away, of a marker of the present invention; I

FIGURE 2 is a bottom plan view of the marker of FIGURE 1;

FIGURE 3 is a sectional view taken along line 3-3 of FIGURE 1 showing the relationship of the various elements of the marker;

FIGURE 4 is a sectional view taken along line 4-4 of FIGURE 1;

FIGURE 5 is a top plan view of another embodiment of a marker according to the present invention;

FIGURE 6 is an alternative bottom plan view of a marker according to the present invention;

FIGURES 7 and 8 are sectional views of the marker of FIGURE 5 taken along the lines 77 and 88, respectively;

FIGURE 9 is a top plan view of a still further embodiment of a marker according to the present invention;

FIGURE 10 is a top plan view of a one-way marker according to the present invention;

FIGURE 11 is a sectional view of the marker of FIG- URE l0 taken along the line 11-11; and

FIGURE 12 is a schematic sectional view of beaded reflex-reflecting materials useful in forming part of the marker hereof.

Referring now to the drawing, it will be seen that the traffic marker 10 of the present invention comprises a base member 12 having a substantially planar bottom 14 and a substantially flat horizontally reflex-reflecting marker 30 fitted into a recess 24 in said base member 12.

Base member 12 is typically a segment of a sphere and measures approximately 3-5 inches in diameter at its base and is about /2 to 4 inch high and may be formed of any suitable material such as malleable iron, high strength plastics or fired clay. The base member 12 may take other forms and thus can be square, rectangular or elliptical; when the base is square or rectangular, the corners are usually taken down to a radius. It is, of course, understood that the base members would be suitably painted or colored. The malleable iron base members are typically painted with an epoxy-based paint; the plastic members would be pigmented during fabrication and the ceramic or clay members would contain additives or ceramic material as the pigment or a pigmented fired ceramic glaze coat. The markers will ordinarily be colored white or yellow (standard traffic marking colors) or may be variously colored to serve special purposes, such as for marking exit or entrance ramps on high-speed highways.

The bottom 14 of base member 12 is substantially planar and may be provided with surface irregularities which may take the form of surface concavities 16 which aid in adhering the marker to the pavement surface. The concavities 16 may be in the form of cavities of various shapes formed in the base during fabrication as shown in FIGURE 2, or may conveniently be in the form of concentric depressions as shown in FIGURE 6. Texturing may be used to produce such surface irregularities.

As previously noted, the top surface 18 of base member 12 is dome shaped and smoothly arcuately convex. A central groove or channel 20 is formed in the top surface 18 and depending on the use to which the marker 10 is to be used, i.e., as a lane delineator where traffic flow is in one direction or as a center line delineator, the groove or channel 20 will partially or completely bisect the top surface 18. Groove or channel 20 is configured so that the bottom surface thereof generally forms a ramp 22. The central portion of said ramp 22 is suitably provided with a recess 24 adapted to receive a substantially fiat horizontally reflex-reflecting marker 30; although a recess, as such, is not necessary. The bottom of said recess 24 may also be provided with a pair of concave depressions 28 conforming to the bottom surface of reflex-reflecting marker 30.

In the embodiment illustrated in FIGURES 1 and 9, the central portion 26 of groove or channel is wider than the remainder of groove or channel 20. Such a widened central portion 26 will serve as additional protection to reflux-reflecting marker 30 against vehicular abrasion in use.

Reflex-reflecting markers 30 comprise preferably a mass in the nature of a rod 50, plus an optional mass or rod 51 aligned with the first rod 50 (at least one and preferably both rods being transparent) and at least one and preferably two layers or strips 52 of reflex-reflecting material inserted between the rods with the reflex-reflecting faces of each layer 52 directed respectively toward the rod with which it is in closest proximity.

Rods

50 and 51 are spaced from each other a distance at least suflicient to allow reflex-reflecting layer 52 to be inserted therebetween.

Strips 52 are bonded together and are firmly bonded (and essentially encapsulated or embedded in resin) in position between

rods

50 and 51, thereby to provide a resulting marker in which the reflex-reflecting material is protected against traflic wear by solid rod-like masses associated integrally therewith. Of course, the binder material 53 located between the reflex-reflecting face of at least one strip 52 and a transparent rod in front of the same must be transparent. In usual practice the binder between the face of the strips 52 and transparent rods in front thereof is transparent in order to achieve reflex-reflective performance for both lateral faces of the reflexreflecting marker 30.

While not absolutely essential, it is preferred to provide a build-up of cured resinous material, or wear-cap 54 over the area of juncture containing the reflex-reflective material between the

rods

50 and 51. Such caps further shield embedded reflex-reflective material within the marker from traffic wear and reinforce the rod members against breakage when the composite marker is positioned with its bottom in recess 24. Reflex-reflecting marker 30 may be modified to consist of only one of the rod elements and associated structure for use as a one-way lane delineator as in FIGURE 10.

Suitable layers or strips 52 of reflex-reflecting material for use in forming marker 30 of the invention are shown in Palmquist et al. US. Patent No. 2,407,680 granted Sept. 17, 1946, the disclosure of which is here incorporated by reference. Briefly, these reflex-reflecting materials include a back reflector 73, a compact monolayer of transparent beads or spheroids 74, and a binder layer 75 to hold the beads in position in front of the reflector 73. The binder layer 75 in these structures has a flat front face; and this necessitates a special relationship between the refractive index of the spheroids 74 and the material of layer 75 interposed in front of the spheroids 74. The relationship is such that the refractive index of the spheroids 74 is at least 1.15 times that of the refractive index of the transparent covering 75 in order to gain the desired intensity of light reflex-reflection. Preferably the relationship is such that the index of the spheroids 74 is at least about 1.3 times that of the transparent covering 75. Additionally, improvements in reflex-reflective brilliancy are gained in structures of this type by spacing the transparent spheroids 74 slightly from the reflective layer 73, as taught in the aforenoted Palmquist et al. patent. This spacing is gradually reduced to Zero as the refractive index of the spheroids approaches a figure of about 1.9 times that of the refractive index of the transparent covering. Since the refractive index of most transparent binders useful in forming structures of this type is at least about 1.3 up to about 1.5 or slightly higher, the refractive index for spheroids for these structures is generally required to be above about 1.8 or 1.9, and preferably above about 2.1, so as to maintain the proper relative relationship between 4 the spheriod and binder refractive indices and reduce the spacing required for brilliant reflex-reflection of light.

Although reflex-reflecting beaded sheet material of the flat front face type as aforenoted is preferred for use in forming structures according to the invention, and allows for thorough embedding of the reflex-reflecting strips within the body of the markers 30, it is also possible to use reflex-reflecting sheet material of the lenticular type in preparing structures satisfying fundamental requirements of the invention. Useful lenticular structures are taught in detail in Gebhard et al. US. Patent No. 2,326,- 634 granted Aug. 10, 1943, the disclosure of which is here also incorporated by reference.

The height of reflex-reflecting marker 30 should preferably not be greater than about 10 or 20 millimeters (between the base surface and the upper or top surface). Area dimensions perpendicular to the height dimension should be at least about 1.2 times greater than the height dimension, and preferably at least about 2 times greater than that dimension. As a practical matter, one area dimension perpendicular to the height dimension should be no greater than 80 times the height dimension; longer markers are susceptible too readily to breakage as traffic passes thereover. Also, from a practical standpoint in regard to conservation of material, the area dimension transverse to the aforementioned area dimension preferably is not greater than about 4 or possibly 6 times the height dimension of the marker.

Reflex-reflective strip 52 has transparent glass microspheres of about 15 to 100 microns in diameter in a compact monolayer transparently spaced by resin in the amount of about 10 or 15 microns from a back reflector of aluminum and held in a resin binder layer of about 1.5 refractive index having a flat front surface. The microspheres in the structure have a refractive index of about 2.26, or about 1.5 times the refractive index of the transparent covering binder.

This beaded reflex-reflective sheet material is suitably coated with about a 6 mil thick coating of a viscous liquid resinous mixture consisting of approximately equal parts of an epoxy resin (Epon 828) and a polyamide resin (Versamid 125). Epon 828 is a liquid epoxy resin, which melts at 812 C., and has a Gardner-Holt viscosity at 25 C. of Z5 to Z6, and an epoxide equivalent of about 190 to 210. In other words, about 190 to 210 grams of this resin contain one gram equivalent of epoxide, i.e., oxirane oxygen. The polyamide resin reacts with the epoxy resin to produce hardening of the composition. Versamid 125, is stated by its manufacturer, General Mills, Inc., to have an average molecular weight of 2,000, an acid number of 7, and a Brookfield viscosity of about 45,000 to 55,000 centipoises at 23 C.

Useful small horizontally reflex-reflecting markers of substantial flatness are taught in detail in Vanstrum United States Patent No. 3,292,507, issued Dec. 20, 1966, the disclosure of which is hereby incorporated by reference.

In the embodiment illustrated in FIGURES 1-4, base member 11 was fabricated of malleable iron and had a diameter of approximately 4 inches with a height of approximately inch. A groove or channel 20 about V inch deep at its maximum depth (i.e., its central point) and about 1.75 inches wide was provided. A central recess 24 measuring about /8 inch by about 2 inches with a pair of grooves 28 was also provided to receive a reflexreflecting marker 30. The bottom 14 of base 12 was provided with surface concavities 16 to assist in adhering the marker 10 to a pavement surface. The concavities 16 were generally crescent-shaped and were approximately /8 inch deep at their deepest points.

Base 12 was painted with an epoxy-based paint formulated from a liquid epoxy resin (ERL-2774), TiO pigment (TiPure R610) and a polyamide resin (Versamid in a ratio of 2:1:2. ERL-2774 is a liquid condensation polymer of epichlorhydrin and Bisphenol A having an epoxide equivalent of 185-200, an average molecular weight of 350-400 and a viscosity at 25 C. in the range of 10,500l9,500 cps.

Reflex-reflecting marker 30 was then cemented in place in recess 24 using a conventional two-part epoxy resin composition.

Traflic markers 10 were cemented in place in pavement surfaces to test their reflection qualities. The markers were set into the pavement surface about A to inch deep in recesses drilled into the pavement with an epoxy resin adhesive composition formulated from an epoxy resin (EC 1614B) and a polyamide resin (Versamid 125) in a 1:1 ratio. EC-1614B is a modified bisphenol A based epoxy resin having an epoxide equivalent of about 160 and a viscosity at 75 F. of about 600,000 cps. as measured on a Brookfield viscosimeter with a No. 7 spindle at 4 rpm. Reflection, both diffuse (daytime) and reflex-reflecting (nighttime) was excellent.

Markers as illustrated in FIGURES 5-8 were fabricated from an epoxy resin composition comprising epoxy resin (EC-1614B) and polyamide resin (Versamid 125) in a 1:1 ratio to which was added 50 p.h.r. TiO pigment (TiPure R610). A groove or channel 20 about one inch wide was formed through the center of top 18 of base member 12. Reflex-reflecting marker 30 measuring about one inch by inch high was cemented in the center of groove 20 with an epoxy resin adhesive. These markers 30 were then installed into pavement surfaces following the earlier described procedure and gave excellent daytime and nighttime reflection.

The marker illustrated in FIGURE 9 is generally similar to the marker of FIGURE 1. However, groove or channel 20 does not extend diametrically through the top 18 of base member 12 but rather only occupies the central portion thereof and is, in effect, formed by building up the edges defining recess 24 on a disc.

The marker of FIGURES 10 and 11 is designed to be used as a one-Way delineator. As clearly shown in the drawings, the central groove or channel extends only past the midline of base 12 by an amount suflicient to accommodate one-half of reflex-reflecting marker 30. In this manner, marker will only perform its reflex-reflecting function when the headlights of a vehicle strike it through the exposed rod 50. It will be readily seen that reflex-refleeting marker 30 may consist of only one rod element 50 and its associated structural elements; in this event, groove or channel 20 would, of course, only extend to the midline of base member 12.

While reflex-reflecting marker 30 has been described herein as comprising a mass in the nature of a rod 50 plus an optional mass or rod 51 aligned therewith and at least one and preferably two layers or strips 52 of reflexreflecting material interposed therebetween, it is contemplated that other reflex-reflecting devices such as cubecorner reflectors reflex-reflecting sheet material preferably protected by a build-up of resinous material and large reflex-reflecting spheres may be substituted therefor.

The traffic markers of the present invention, because of their raised three-dimensional shape, perform an audible delineation function in addition to their diffuse and reflexreflecting functions by alerting the driver when a car wheel is beginning to cross into another lane of traffic by readily noticeable rumbles or bumps as the car wheel travels thereover.

What is claimed is: 1. A tratfic marking structure comprising in combination a tough wear-resistant base member having a substantially planar bottom surface provided with surface irregularities for adhesive attachment to a pavement,

the top surface thereof being smoothly convex and having a channel formed therein,

the central portion of said channel having a transverse recess, and

a small horizontally reflex-reflecting marker of substantial flatness aflixed within said recess in said channel,

said reflex-reflecting marker comprising a layer of rereflex-reflecting elements vertically oriented and a protective transparent facing member over the layer of reflex-reflecting elements.

2. A traflic marking structure according to claim 1 wherein the base member is a segment of a sphere having a diameter of about 3 to 5 inches at its base and a height of about one-half inch to about one inch.

3. A traflic marking structure according to claim 2 wherein said base member is formed of malleable iron.

4. A traffic marking structure according to claim 2 wherein said base member is formed of a high strength plastic.

5. A traffic marking structure according to claim 2 wherein said base member is formed of fired clay.

6. A traffic marking structure according to claim 1 wherein the channel in the top surface of the base member completely bisects said top surface.

7. A trafiic marking structure according to claim 1 wherein the channel in the top surface of the base member extends from the outer edge of said base member to its approximate midline.

8. A traflic marking structure comprising in combination a tough wear-resistant base member in the form of a segment of a sphere having a diameter of about 3 to 5 inches at its base and a height of about one-half inch to about 1 inch having a substantially planar bottom surface provided with surface concavities for adhesive attachment to a pavement,

the central portion of said channel having at least one transverse concave depression therein, and

a small horizontally reflex-reflecting marker of substantial flatness, said reflex-reflecting marker having an essentially flat base surface with area dimensions perpendicular to the height dimension being at least 1.2 times greater than said height dimension and no greater than times said height dimension, said reflex-reflecting marker comprising at least one layer of a reflex-reflecting monolayer of glass beads having a refractive index of at least 1.7 and underlying specular reflective means oriented essentially perpendicular to the flat base surface thereof, and

at least one solid scratch-resistant transparent rod-like mass oriented in front of said layer of reflex-reflecting material within the dimensional limits aforedefined and firmly fixed by transparent cured resinous bonding material in front of said reflex-reflecting material,

said reflex-reflecting marker being afi'ixed within said channel with the bottom portion of said at least one solid scratch-resistant transparent rod-like mass fitting within said at least one transverse concave depression.

References Cited UNITED STATES PATENTS 1,927,756 9/1933 Ross 941 5 2,185,488 1/1940 White 941 5 2,321,476 6/1943 Foster 941.5 3,179,009 4/1965 Sheflield 941.5 3,292,507 12/1966 Vanstrum 941.5 D. 207,038 2/1967 Haley D 72-1 JACOB L. NACKENOFF, Primary Examiner