Method for forming traffic regulating signs on road surfaces

Abstract

The specification describes a method and a tape material for adhesively securing a traffic regulating sign or mark on a road surface, provided by laying on and pressing against a primer layer, preliminarily provided on a road surface, a tape material having a lower face designed to be juxtaposed on said primer layer, wherein said tape material lower face is provided with a lower layer of a compound which is not sticky at ambient temperature and comprises at least one component adapted to be modified and impart adhesiveness to said lower face, upon a thermal or physical or chemical action exerted by said primer layer upon actual contact of the tape material therewith by means of a resulting interfacial inter-exchange relationship.

Description

BACKGROUND OF THE INVENTION

a. The Field of the Invention

This invention is concerned with methods and means for providing a road surface with traffic regulating signs, generally but not exclusively consisting of continuous or interrupted lane dividing or laterally defining lines. More particularly, this invention is concerned with the art of forming said traffic regulating lines or signs by laying on and adhesively securing to a preliminarily prepared road a strip material having a lower face adapted for juxtaposition and adhesive connection to a prepared and essentially smoothed area of the road blanket and an upper face for forming the sign and possessing suitable properties for good visibility, wear resistance and so on.

B. The Prior Art

These methods are well known in the art and widely published. The use of factory made strip materials, which can be stocked in coiled bobbins, carried to the locations where the traffic regulating sign is to be formed on a road surface and then un-wound to progressively lay the material on such surface, is very advantageous. The road surface preparation and the laying down of the materials can be mechanically made with a minimum of traffic disturbance.

For most complete details of such art, with relation to the laying-down machines, the strip material and the road surface preparation, reference is made to several of Applicant's prior patents such as U.S. Pat. Nos. 3,007,838, No. 3,155,564, No. 3,235,436, No. 3,262,375 and No. 3,399,607.

The strip material is essentially of elasto-plastic nature and its body may be formed from a variety of compositions. Examples of such compositions have been described, among other publications, in the Applicant's prior U.S. Pat. No. 3,587,415, where the compositions for forming the "base strip" have been described. In this latter patent specification there has been described also how the upper face of the strip material can be advantageously provided with means for improving its anti-skid properties and its nightime visibility. Other means for further improving the above and other properties have been made open to public inspection and knowledge by the French Pat. Publications No. 2,085,900, No. 2,086,257 and No. 2,097,941.

In view of the above extensive publications relating to the prior art of the invention, any further discussion of is superfluous.

The methods and means heretofore proposed and made known are however subject to certain objections and limitations; such objections are principally concerned with the provision of an extremely tacky surface layer at the lower face of the strip material and/or at the upper layer of the prepared area of the road blanket, for ensuring a firm adhesive connection. This sticky surface layer can be factory provided on the lower face of the strip material and then protected by a paper or plastic film for preventing the coils of the wound bobbin of the material from adhering to each other and for facilitating the manipulation of the material prior to the laying-down thereof, and means are provided for removing such protective film just prior to laying the material on the road.

The prior art includes preferably the provision of means for applying to the upper face of the prepared road blanket or preferably to the lower face of the strip material a thin layer of highly viscous adhesive. This provision requires rather costly and complicated means and devices and a very careful control and operation of such devices and of the means provided for applying and spreading the adhesive on such face in measured amount. It has been also heretofore proposed to provide the layer of the compound, preliminarily applied on the road blanket for preparing the road surface prior to laying-down the strip material thereon (such layer is currently referred to as "primer layer" in the art, and thus defined as this description proceeds and in the appended claims) with a tacky upper surface. This method is also seriously objectionable both because this surface is extremely receptive to dirt, sand, powder and so on, and because the primer layer, the width of which is necessarily larger than the sign forming strip or tape material, will form on the road surface sticky portions at either side of the applied tape material.

BRIEF SUMMARY OF THE INVENTION

It is therefore a principal object of this invention to provide new and improved methods, steps, means and materials by which the above and other objections and limitations of the prior art can be eliminated or at least greatly reduced.

Essentially, according to the invention, the sign forming tape material is provided, at its face designed to be contacted with, juxtaposed and pressed on the upper face of the prepared road surface, with a layer of a compound which is not sticky at least at ambient temperature, but capable of providing an adhesive bond with the upper surface of the primer layer on the road, upon a physical and/or a chemical modification occurring in the compound adjacent to the tape material - primer layer interface and promoted by actual contact and pressure of said sign forming tape material on said primer layer, said modification occurring by an inter-exchange originated by said actual contact and occurring through said interface.

It is therefore a specific object of this invention to provide a new and advantageous tape material, adapted to be laid on and adhesively secured to the upper face of a primer layer coating a selected area of a road surface to form a traffic regulating sign thereon, the said tape material having a visible sign actuating upper face, a body of known elasto-plastic nature and a lower face forming a potentially adhesive lower layer which is not sticky at ambient temperature and including at least one component capable of being modified so as to promote a physical bond with said primer layer when contacted with and pressed on the upper face of said primer layer.

According to an embodiment of the invention, the said potentially adhesive lower layer comprises a thermoplastic resinous component capable of acquiring adhesive properties if thermally plastified, and the tape material is laid on and pressed over a preliminarily heated primer layer to promote a heat exchange at said interface, leading to an adhesive bond between said lower layer of the tape material and the primer layer on the road surface. The preliminary heating of the primer layer is preferably provided by forming said primer layer of a meltable compound and laying the molten compound on the road surface blanket and then laying the tape material on the still hot primer layer.

According to another embodiment of the invention, the said potentially adhesive lower layer comprises a resinous component capable of chemically reacting in particular to cross-link with another component present in the primer layer composition to provide the desired physical bond at said interface. In such occurrence a heat inter-exchange at said interface can be preferably provided for promoting and/or accelerating the chemical reaction.

According to a further embodiment of the invention, the said potentially adhesive lower layer comprises a resinous component capable of acquiring sticky properties when partially dissolved by compatible solvents, and the tape material is laid on and pressed against a primer layer including an excess of at least one of said compatible solvents.

Further embodiments of the invention comprise combinations of the above indicated modes for providing a bond forming inter-exchange at the interface provided by the actual juxtaposition and pressure of the potentially adhesive lower layer preliminarily and factory provided at the lower face of the tape material on the upper face of a primer layer preliminarily provided on the selected area of the road surface to be marked.

These and other features and advantages of the invention will be now made apparent in and by the following description of exemplary modes of making use of the invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

EXAMPLE 1

Thermally promoted bond.

According to this example, the potentially adhesive lower layer consists of a rather thin, such as from 0.2 to 0.8 mm, film applied, during the manufacture of the tape material (or of the sheet stock material from which the tape material is cut, according to current art) to the lower face of a sign forming article, the body and the upper layer of which are in turn made according to the known art, such as described in any of the prior patents and patent publications referred to above. The said lower layer is made of a compound including preferably a synthetic rubber.

The primer layer is made, according to current art, of a compound prevailingly consisting of bitumen and it is applied on and smoothed over the road blanket, also according to current art, in its molten or fluidified state, and the tape material is laid thereon when the said primer layer is still hot. In some occurrences, it might be expedient to apply the primer layer well in advance to the laying down of the tape material; in such occurrence such primer layer may be re-heated by means of a gas burner, for example.

The said primer layer has preferably the following composition, in parts by weight:

Bitumen parts 160 "Chemigum No. 600" (Goodyear) (1) parts 5 Resin "Eskorez 1101" (Esso) (2) parts 10 Coumarone-indene resin parts 10 Methylene chloride parts 10

The said potentially adhesive layer has preferably the following composition, in parts by weight also:

EXAMPLE 2

Bond promoted by combined chemico-physical action

In this occurrence, the interfacial bond is prevailingly provided by a chemical cross-linking promoted between resinous components appertaining to the potentially adhesive lower layer and respectively to the primer layer. Such components consist of like resins or of resins of similar nature and capable of cross-linkage. Preferably, the resinous component in the said lower layer is selected from those wherein a suitable hardener (provided in the compound of the primer layer) is highly soluble. As a consequence of such provision, when the tape material is contacted with and pressed on the primer layer, the said hardener is at least partly transferred through the interface and promotes the cross-linking of such resinous component, leading to the desired physical bond of the tape on the primer layer, upon a chemical action.

Of course, more than one reaction promoter can be made use of, such promoters being chosen from those capable of co-reacting and operating synergically, said promoters (catalysts, accelerators) being individually present in the said potentially adhesive layer and primer layer, so that their co-action and synergy can be originated by the actual contact between the tape material and the primer layer only.

By preliminarily heating the primer layer, such as described in Example 1, a deeper and more intimate bond can be provided at either side of the interface, upon the thermally promoted plasticization and softening of the juxtaposed compounds.

The potentially adhesive lower layer of the tape material is preferably compounded as follows, in parts by weight:

"Chemigum No. 600" parts 60 "Neoprene AD" (DuPont) or "Bayprene" (Bayer) parts 70 Magnesium oxide parts 4 Resin "Durez 12603" (Hocker Chem.) (3) parts 60 Zinc oxide parts 5 Baryta parts 60 (3) as an example of a phenolic resin.

In turn, the primer layer is preferably compounded as follows, in parts by weight:

Bitumen 40/50 parts 140 Resin "Eskorez 1101" parts 40 "Oronite 128" (Chevron) (a plasticizer) parts 20 "Desmodur R" (Mayer) (an isocyanate resin) parts 15 Methylene chloride parts 65

EXAMPLE 3

Bond promoted by use of solvents

The potentially adhesive lower layer of the tape material can be provided by making use of either of the compounds described in the Examples 1 or 2. The layer is factory applied to the lower face of tape (or stock sheet) body, upon plasticization of the compound by means of suitable solvents, according to current art. These solvents are eliminated until the lower face of the tape is no longer tacky, preliminarily to winding the tape onto bobbins for storage, transportation and application on the road surface.

The ability to adhesively connect itself to the primer layer, by part of the tape lower layer, is restored by adding to said lower layer a certain amount of solvent equal or equivalent to those used for plasticizing the compound, said solvent being present, as an excess of solvent, in the primer layer. For example, methylene chloride can be made use of as a plasticizing solvent for the potentially adhesive lower layer of Example 1, such chloride being itself the solvent for the primer layer of same Example 1. In this occurrence, however, the solvent is provided in a greater amount, that is in excess, in the primer layer compound, for providing the excess which will be transferred, through the interface, from the primer layer to the lower face of the tape material laid on and pressed upon said primer layer, the compound of which comprising, in this occurrence, from 50 to 60 parts by weight of methylene chloride.

The most suitable amount of excess solvent can be easily found by experiments. In general, a greater excess of solvent will be convenient when operating in summertime or in general at an ambient temperature of at least 15.degree.C or preferably 20.degree.C. When the road marking is being made at lower temperature, the use of more easily volatile solvents, such as a suitable "Freon" (a series of well known fluorine compounds) is preferred.

The use of solvents for imparting adhesiveness to the lower face of the tape material, upon contacting it with a road surface, is extremely simple and, while such use might require a longer time for having the bond completed and the road sign set for traffic passage, this specific method can be sometimes preferred in view of its simplicity, the road marking being possible even by purely manual operations or by means of the simplest tools.

Claims

I claim:

1. A method of forming a traffic-regulating indicium on a road surface, comprising the steps of applying a primer layer to the road surface; and effecting direct contact between said primer layer and a substantially non-adhesive surface of a marking strip, said primer layer and said strip surface cooperating in a manner such that a transformation effecting bonding between said primer layer and said strip surface without interposition of a bond-forming substance between the same, and which transformation is absent in the absence of said direct contact, occurs in response to said direct contact.

2. A method as defined in claim 1, wherein said primer layer comprises at least a substantial proportion of bitumen.

3. A method as defined in claim 1, said primer layer being in a heated condition when applied to the road surface; and wherein said direct contact is effected while said primer layer is still in a heated condition, said transformation occurring due to the heat of said primer layer and comprising a change in said strip surface from a substantially non-adhesive condition to an adhesive condition.

4. A method as defined in claim 1, said primer layer comprising a solvent for said strip surface; and wherein said transformation comprises at least partial dissolution of said strip surface.

5. A method as defined in claim 4, wherein said strip surface comprises a resinous component and said solvent at least partially dissolves said resinous component.

6. A method as defined in claim 1, wherein said strip surface comprises a resinous component which is capable of undergoing cross-linking with at least one component of said primer layer, and said transformation comprises cross-linking of said one and resinous components.

7. A method as defined in claim 6, wherein the interface between said primer layer and said strip surface is in heated condition so as to promote cross-linking of said one and resinous components.

8. A method as defined in claim 6, wherein said primer layer comprises an agent for promoting cross-linking of said one and resinous components.

9. A method of forming a traffic-regulating indicium on a road surface, comprising the steps of applying a primer layer to the road surface, said primer layer including at least one component which is capable of undergoing cross-linking, and said primer layer including an agent which promotes cross-linking of said one component; and effecting direct contact between said primer layer and a substantially non-adhesive surface of a marking strip, said strip surface including a resinous component which is capable of undergoing cross-linking with said one component so that bonding of said marking strip to said primer layer upon contact between said strip surface and said primer layer occurs without interposition of a bond-forming substance between said strip surface and said primer layer, and the interface between said primer layer and said strip surface being in heated condition so as to promote cross-linking of said one and resinous components.

10. A method as defined in claim 9, wherein said primer layer comprises a minimum of substantially 50 percent by weight of bitumen.