CN1189865A - retroreflective material - Google Patents

Abstract

The present invention discloses a retroreflective pavement marking material (10) comprising an exposed lens-type retroreflective sheet (12) on its top surface, the sheet being a single layer containing a plurality of retroreflective elements, a plurality of first portions of the single layer being arranged in a protruding cross section (18), and a plurality of second portions of the single layer being arranged in a lower, substantially planar position (20).

Description

retroreflective material

field of invention

This invention relates to retroreflective marking materials.

background of the invention

Pavement markings (such as those located on the centerline and sidelines of the road) are very important to guide motorists. Pavement marking materials are used as traffic control signs and have many uses such as short lane markings on roads, stop poles, pedestrian pavement markings at road intersections and long lane markings, etc. A common form of pavement marking material is an adhesive backed adhesive tape which is applied in desired lengths to the pavement at the required locations; the top side of the tape is of a selected color and generally has retroreflective properties.

Currently, the retroreflection mechanism of many planar pavement markings generally relies on an exposed lens optical system, which is transparent microspheres partially embedded in an adhesive layer containing reflective pigment particles, such as titanium dioxide (TiO ₂ ) or lead chromate (PbCrO ₄ ). In use, light from a vehicle's headlights enters the microspheres and is refracted onto the reflective paint. A part of the light is reflected back toward the vehicle along the original incident light path, so that the driver can see it.

Presently existing thin-section pavement markings provide an effective retroreflective response over a narrower range of incidence angles than is sometimes required. For example, flat pavement markings, whose function relies on microspheres partially embedded in a layer containing the aforementioned diffuse pigment, are readily visible at distances of about 80 meters or less, but retroreflective brightness diminishes beyond that distance , partly because the incident light has a relatively large angle of incidence, and partly because the retroreflective brightness itself is limited.

U.S. Patent Nos. 4,388,359 to Ethen et al, 4,988,555 to Hedblom, 4,988,541 to Hedblom and 5,227,221 to Hedblom disclose a pavement marking sheet in which microspheres have raised portions partially embedded in a pigmented binder layer in, and protrude from the layer. This structure can improve the retroreflection brightness at larger incident angles, but the manufacturing cost is expensive.

In addition, the failure mode of many pavement marking materials is that its adhesion to the road surface is weakened or even lost, so that a considerable part of the marking tape is displaced.

There is an urgent need for low-cost thin-section retroreflective products, which have high retroreflective brightness even at large incident angles, and can maintain effective retroreflective brightness for large incident angles even when wet, and are durable. durable. In addition, there is a need for retroreflective articles with effective retroreflective response over a wide range of angles of incidence that can be used on vertical surfaces such as guardrails, cattle barriers, piers, walls, and the like.

Overview of the invention

The present invention provides novel materials with surprisingly effective retroreflective properties that are relatively inexpensive to manufacture. The material of the present invention has effective retroreflective properties over a relatively large range of incident angles (eg, 85° or greater) and is well suited for use on vertical and horizontal surfaces. In addition, the marking material of the present invention has an amazing adhesion to the road surface and thus has a long service life.

Some terms used in this application are collectively listed at the end of this specification. Much of the description below is written with specific reference to embodiments useful as some of the retroreflective pavement marking materials of the present invention. It should be understood that many aspects of these embodiments are equally applicable to embodiments of retroreflective markings on vertical surfaces.

Briefly, the retroreflective material of the present invention has a top layer comprising a plurality of exposed lenticular retroreflective elements (e.g., transparent microspheres) partially embedded in a binder layer containing pigment particles and partially protruding from the Outside. A first portion of the top layer is arranged in an outboard (ie generally perpendicular to the layer) section and a second portion of the top layer is arranged in a lower, sometimes substantially planar position. Generally, the material of the present invention will comprise a plurality of said first and second parts throughout a continuous sheet.

The retroreflective marking material of the present invention can be made in flexible form and can be made in desired colors. In addition, the material provided by the invention can be made into a thin section, has good shape retention, and can be perfectly attached to the road surface. When manufactured from suitable materials, the retroreflective marking materials of the present invention can resist the damaging effects of traffic, can withstand contact with water, salt, oil, ultraviolet light, sand abrasion, high temperature, etc. , this advantage makes them very suitable for road use. They can be manufactured in a continuous process and are relatively inexpensive to manufacture. When the marking material of the present invention is used on roads as traffic control signs, the reflected light can be easily seen by drivers, thus improving safety.

The retroreflective articles of the present invention are particularly useful in applications where the incident light has an angle of incidence greater than about 85°, such as pavement markings. The article is also well suited for applications where incident light is incident from many directions. Examples include road intersection signs and what are commonly known as level signs. Illustrative examples of horizontal markings include the legends and symbols used to represent parking barriers that are commonly found on the pavement of parking lots, and the arrows and lane markings that are found on the pavement of road intersections.

In addition, the retroreflective articles of the present invention are well suited for use on vertical surfaces, especially vertical surfaces that have a relatively large angle of incidence when viewed, such as guardrails, building walls along passageways, cattle pens, bridge piers, columns, and cylindrical traffic signs. wait.

Brief description of the drawings

The present invention will be further described below with reference to the accompanying drawings, wherein:

Figure 1 is a plan view of a portion of an illustrative pavement marking material of the present invention;

Fig. 2 is a sectional view of the material shown in Fig. 1;

Figure 3 is a cross-sectional view of another illustrative pavement marking material of the present invention.

The drawings are idealized and not drawn to scale, and are presented for illustration only and not limitation.

Detailed Description of Illustrative Embodiments

Articles of the present invention generally include a retroreflective topsheet, a configuration member, or optionally a backing material, and an adhesive layer. Forming members are used to form contoured extensions in an article. The term "protruding" as used herein means that the first portion is generally raised relative to the second portion and that the pavement marking is generally applied on a horizontal surface. It should be understood that it can also refer to the form in which the first part protrudes relative to the second part in a vertical sign.

Illustrative marking materials of the present invention are shown in FIGS. 1 and 2 . Material 10 includes a top layer 12 having microspheres 16 and skid particles 17 protruding from an adhesive layer 14 . The first portion 18 of the top layer 12 is arranged in a profiled profile and the second portion 20 of the top layer 12 is arranged in a lower, sometimes substantially planar position. The marking material 10 also includes a backing, which sometimes also contains a conformance layer (conformance layer) 22 and an adhesive layer 24, by which the marking material can be fixed to a desired substrate, such as a road (in the figure not shown). In the embodiment shown, the first part 18 is raised above the second part 20 by the action of the profile 19 .

The many component parts of the retroreflective sheeting should remain bonded together in all types of weather conditions, even under repeated impact stresses and shears caused by road traffic vehicles passing the retroreflective sheeting when used for pavement markings. It can also maintain adhesion under shear stress conditions.

The top layer has microspheres protruding from the binder layer containing pigment particles. An advantage of such lens systems is that they can be made in a variety of desired, bright, ie true colors displayed in daylight. This is particularly useful for embodiments used on concrete pavements or other relatively bright pavements where brighter colored signs should display better contrast and visibility during daylight hours. By selecting the appropriate pigments and dyes for the adhesive layer, and choosing either colorless or colored microspheres, the desired color can be achieved in daylight as well as in retroreflective viewing conditions.

Typically in the case of pavement markings, the backing material of the article may also have a conformal layer and/or a scrim layer, the reasons for using these layers are known in the art. Those of ordinary skill in the art can readily select suitable conformal layer and scrim layer materials.

The function of the adhesive is to bond the retroreflective article to a surface, such as a pavement. If desired, an adhesive layer or primer can be applied to the surface prior to laminating the retroreflective article to the surface. Selection of a suitable adhesive (such as pressure sensitive adhesives, hot melt adhesives, reactive adhesives, etc.) depends in part on the conditions of the application, the surrounding environment of the substrate, and the layers of the article to which the adhesive layer is to be bonded nature. A person of ordinary skill in the art can readily select a suitable adhesive layer.

Generally, the pavement marking material of the present invention can be wound into a roll. In this case, it is necessary to use a release liner or a release treatment, such as silicone, on the top surface of the marking material.

As mentioned above, the sections of the top layer are such that the respective first portions are elevated in profile above the respective second portions. These protruding portions of the profile in vertical section have several advantages, such as: (1) more efficient retroreflection of light at greater angles of incidence, (2) possible rainwater will flow away, (3) As the vehicle tire repeatedly contacts the protruding portion of the profile, the adhesion of the pavement marking material to the road surface is enhanced.

The protruding cross-section of suitable shape is obtained by the setting action of the configuration member, which may be a single member, such as a layer of interconnected fiber web, or a row of spaced members, such as a row of independent fibers or nodules. A preferred forming member is, for example, a layer of point bonded nylon or polyester web, the fibers being discontinuous with openings between the fibers. These openings allow surrounding material components such as the top layer and adhesive layer to be bonded together directly through the form. The formations may be of any suitable shape so long as they are capable of elevating portions of the retroreflective sheeting as described herein. The formations should be flexible so as to conform easily to the road surface.

The structural members used in the present invention are generally polymers. Illustrative examples of polymeric materials include polyurethanes and polyolefin copolymers such as polyethylene acid copolymers, including ethylene-methacrylic acid copolymers (EMAA), ethylene-acrylic acid copolymers (EAA), Ionically cross-linked EMAA or EAA.

In some embodiments, the first portion may be in the form of discrete protrusions. This can be obtained by using a row of nodules as a formation. These nodules can be largely separate or joined by relatively thin filaments. The latter embodiment allows for easier handling during the manufacture of the retroreflective marking material.

In some embodiments, the first portion may be in the form of strips, which may be substantially non-intersecting or intersecting in the form of an interconnected network. Each strip may be substantially straight or curved, and they may be arranged in a sinusoidal array of dimples or any other desired shape. The shape and arrangement of the first part determines the shape of the second part. Some illustrative examples of second part shapes are rectangle, rhombus, hexagon. If the first parts are intersecting, the second parts can be separated from each other. If the first parts are not contiguous and do not intersect, then the second parts are adjacent to each other. These arrangements can be used in combination as necessary.

The other components of the article should have sufficient conformality to give the desired profile of the top layer overhanging the profile. Preferably, the features should be self-adhering to the conformal layer (if present), as this is believed to result in a more durable final product. In addition to serving the functions disclosed herein, the mesh formations can enhance the mechanical properties of pavement marking materials similar to the scrims disclosed in US Patent Nos. 4,146,635 to Eigenmann and 4,299,874 to Jones et al.

In some embodiments, some of the portions of the profile protrude higher than other portions of the first portion. For example, in the rectangular embodiment described above, the portion of the profile projecting perpendicular to the direction of traffic travel is raised somewhat higher than the portion parallel to the direction of traffic travel. In this way, the higher profile overhangs provide effective retroreflective properties, while the lower profile overhangs allow rainwater (if present) to run off.

Regardless of the shape of the profile protrusions, the height of the profile protrusions is preferably chosen taking into account the distance between these parts. For example, the protruding portions of the profiles along the line of sight of approaching vehicles should be spaced far enough apart so that shadowing is minimized. The distance between the protruding parts of the profile (ie the width of the second part) is preferably at least 3mm wide. Generally, the top of the first portion is at least 0.1 mm higher than the second portion, preferably about 1 to 4 mm higher. The profile extensions can be spaced closer together without appreciable effect on retroreflective brightness, but this would require more structural members than is optimal. Likewise, the spacing of the more distant profile overhangs could be used, but this would result in a reduction in brightness in the nearer field of view. However, brightness is not affected in the far field of vision. As used herein, "closer field of view" refers to a relatively short distance between the vehicle and the material of the invention, such as a distance of about 30 meters. "Larger viewing area" means that the distance between the vehicle and the material of the present invention is relatively long, such as a distance of about 120 meters. Those skilled in the art can select and design a suitable protruding shape according to the present invention.

The marking material of the present invention is readily prepared by laminating the preformed top layer, form members, conformal layer (if present) and adhesive layer simultaneously or separately in the desired sequence. If desired, other components may be assembled first and then the top layer formed thereon.

The advantage of the present invention is: the mesh that is used as configuration member is easy to process, and is easy to add in the marking material to obtain the profile protruding section of desired, and this is compared with selectively molding protrusion in a member and then applying. The method of coating or forming the adhesive layer material with the raised microspheres thereon is easier and less costly.

In some embodiments, it is desirable to embed slip-controlling particles (such particles are sometimes referred to as anti-skid particles) in the top layer in order to improve the traction of passing vehicles thereon. Anti-slip particles are known in the art. A person skilled in the art can readily select a suitable embodiment.

Generally speaking, non-slip particles can be randomly sprinkled on the top layer when the adhesive is in a soft state. It has been found that it is preferable to locate the non-slip particles near the peak of the protruding portion of the profile. For example, a retroreflective sheeting having a protruding portion is conformally coated on the peak of its first portion with an adhesive composition, and the retroreflective sheeting is sprinkled with a quantity of non-slip particles while the adhesive is still wet. Because the rest of the sheeting is dry, the particles stick only to the wet areas. Excess anti-slip particles are vibrated from the sheet. Next, the sheet is sent through a series of ovens to dry and cure the wet adhesive. As a result, the anti-slip particles are fixed in the peak area of the protruding portion of the profile, whereby anti-slip performance is obtained. This processing method will cause some loss of retroreflective performance.

The material of the invention may be wound into rolls. The protrusions formed by the protruding sections of the profile do not yet interfere with the winding process.

In a representative embodiment as a pavement marking for marking a roadway, the material of the present invention is about 7.5-30 centimeters (3-12 inches) wide and at least 30 centimeters (12 inches) long. Pavement markings are usually much longer. The marking materials of the present invention are generally manufactured to dimensions that conform to standard materials. In the United States, pavement marking tapes are generally about 4, 6 or 8 inches wide. In Europe, pavement marking strips are generally about 15 or 30 cm wide.

term set

This article uses some definitions:

The "reference axis" is a line normal to the point of incidence of light rays on the retroreflective article.

"Axis of incidence" is the axis determined by the optical path of incident light from a light source (such as an automobile headlight) to a point of incidence on an article.

The "angle of incidence" (sometimes also denoted β) is the angle between the reference axis and the axis of incidence.

"Axis of observation" is the axis determined by the optical path of reflected light from the point of incidence on the article to the point of observation (eg, the eye of a motor vehicle driver).

"Observation angle" (sometimes denoted a) is the angle between the incidence axis and the observation axis.

"Plane of incidence" is the plane defined by the reference axis and the axis of incidence.

"Observation plane" is the plane defined by the observation axis and the incidence axis.

Various modifications and alterations to this invention will become apparent to those skilled in the art without departing from the scope and spirit of this invention.

Claims (19)

1. A retroreflective marking material comprising (1) a top layer comprising a plurality of microspheres partially embedded in and protruding from the front face of an adhesive layer containing pigment particles, the A plurality of first portions of the top layer are arranged in a profile protruding section, and a plurality of second portions of the top layer are arranged in a lower substantially planar position; The first and second parts play the role of configuration; (3) adhesive layer. 2. The material of claim 1, further comprising a conformal layer. 3. The material of claim 2, wherein the conformal layer is disposed between the top layer and the configuration members. 4. The material of claim 2, wherein said conformal layer is disposed between said form member and said adhesive layer. 5. The material of claim 1, wherein the top end of the first portion is raised and protrudes at least 0.1 mm above the second portion. 6. The material of claim 1, wherein the top end of the first portion is raised and projected at least about 1 to 4 mm above the second portion. 7. The material of claim 1, wherein the second portion is at least 3 millimeters wide. 8. The material of claim 1, wherein the first portion is in the form of a discontinuous protrusion. 9. The material of claim 1, wherein the first portion is strip-shaped. 10. The material of claim 9, wherein said bands are substantially disjoint. 11. The material of claim 9, wherein said strips intersect to form an interconnected network. 12. The material of claim 9, wherein said strips are substantially straight. 13. The material of claim 9, wherein said strips are arranged in a sinusoidal array of dimples. 14. The material of claim 1, wherein said first portion is interconnected such that said second portion is one of the following shapes: rectangular, rhombus, hexagonal. 15. The material of claim 1, wherein the retroreflective brightness of the material at angles of incidence greater than 85° is higher than the retroreflective brightness of the article without the first portion. 16. The material of claim 1, further comprising anti-slip particles protruding from the front side of the material. 17. The material of claim 1, wherein said markers are about 7.5 to 15 centimeters wide and greater than 30 centimeters long. 18. A pavement marked with the material of claim 1. 19. The material of claim 1, wherein said material is used on a vertically disposed surface selected from the group consisting of guard rails, cattle pens, building walls, fences, utility poles, traffic cones, and The side of the vehicle.