US 2268537 A
Description (OCR text may contain errors)
Dec. 30, 1941. 1 SSSS ER 2,268,537
f Imm @@lww Patented Dec. 30, 1941 y OFFICE ROAD MARKER Leroy Shuger, Baltimore, Mdv
Application May 19, 1939, Serial No. 274,666
This invention relates to surface markers and more particularly to markers embodying a reiiecting binder and transparent autocollimating units.
Prior to the instant invention it has been suggested that glass spheres be laid in a paint when the latter is in a semi-dry or tacky condition. This procedure has not always proven satisfactory for in some cases the spheres sink down to the base on which the paint has been applied and when this condition occurs, the marker will not act as desired for no reflecting medium will be about the lower portions of the spheres which is absolutely essential for autocollimation.
It has further been suggested that center lines and lane lines on roadways which are subjected to vehicular trailic be fabricated of paint incorporating minute glass spheres but such lines have been relatively short-lived for the spheres soon become disengaged from the paint and the corresponding autocollimating effect which the spheres attribute to the lines is lost. The presence of autocollimating units such as glass spheres in a lane line protects the paint or reilecting binder from wear due to vehicular traffic and as long as the spheres are held to the paint or binder,
the marker shows little wear but as soon as the spheres become dislodged, wear of the marker is accelerated.
It is an object of the instant invention to provide a combination marker including a reflecting binder and autocollimating units wherein the binder is of such peculiar and critical nature as to tenaciously hold the autocollimating units in a desired relation to give proper autocollimating y eiect for a relatively long period of time.
It is a further object of the instant invention to provide a combination marker including a reilecting binder and a series of autocollimating units wherein the proportions of some of the ingredients of the binder are such as to impart a special characteristic thereto involving the tenacious holding of the autocollimating units to the marker.
It is a still further object of the invention to provide a combination marker comprising a reecting binder and autocollimating units wherein the lm thickness of the binder in its Wet condition bears a special relation to the size of the autocollimating units whereby when the marker is dried the desired eect will result.
Other objects and the nature and advantages of the invention will be lapparent from the following description taken in conjunction with the accompanying drawing, wherein:
Fig. l is a view in perspective, taken at night time, of a roadway normally bearing vehicular traffic having a center line applied thereto in accordance with the invention and. a vertical marker at the side of the roadway also in accordance with the invention;
Fig. 2 is a schematic illustration of a bucket of reflecting binder illustrating the proportions of volatile ingredients to non-volatile ingredients;
Fig. 3 is a schematic illustration relating to Fig. 2 and depicts an autocollimating unit partially embedded in a wet film;
Fig. 4 is a view similar to Fig. 2 with the volatile ingredients removed;
Fig. 5 is a view similar to Fig. 3 but related to Fig. 4 and depicts an autocollimating unit partially embedded in a lm which has dried;
Fig. 6 is a View similar to Fig. 2 illustrating the proportions of pigment to the remaining of the non-volatile ingredients; and,
Fig. 7 is a chart and curve illustrating the abrasion ratings of different sample reflecting binders in which the ratio of pigment volume to total non-volatile volume is varied.
Referring to Fig. 1 a roadway I 0 is marked with a center line Il fabricated of reflecting binder including ingredients such as specified later in detail and a series of autocollimating units in more or less embedded relation. At the side of the roadway a marker l2 has applied to its Vertical surface l5 an insignia IB including a reilecting binder and a series of more or less embedded autocollimating units such as for example relatively small glass spheres. The marker may be fabricated by applying to the surface to be marked a reflecting binder which application may be made by spraying, brushing, dipping, or otherwise coating. While the marker is in a Wet, semi-wet, or tacky condition the autocollimating units are distributed over the surface thereof either by hand or with a mechanical dispenser not shown. The reflecting binder is then permitted to dry and hold the autocollimating units in such relation thereto as to eiect the reflection of light back to the source emanating light thereto.
While ordinary paint may be generally divided into two parts, namely, the pigment and the vehicle, it is preferred in the exposition of the instant invention to denote the primary division of the binder as volatile portion and non-volatile portion of the ingredients. The reflecting binder may generally comprise volatile material Il and non-volatile material I8 in the proportions schematically depicted in the bucket I9 in Fig. 2. In order that the binder have good package characteristics, and permit of ready application, it is essential that a suillcient portion of volatile ingredients Il be included. To provide for reflection which is absolutely essential to the finished marker, the non-volatile ingredients I8 must include pigment. In addition to the pigment there must be included other non-volatile ingredients which will serve to hold thepigment to the marker after the volatile portion has evaporated. The non-volatile ingredients other than the pigment may comprise oils or resins or both. The resins may be natural or synthetic.
The following pigments or related pigments are in general suitable as ingredients for white markers: titanium pigment such as for example titanium dioxide, titanium dioxide extended with barium sulphate or calcium sulphate, or magnesium silicate; Izine sulphide; and normal or high strength lithopones. For colored markers other than white the following pigments or related pigments are suitable: lead chromates, zinc .chromates, siennas, umbers, iron oxides, inorganic or organic reds. Reinforced pigments sometimes referred to as inerts or extenders may also be used such as for example: Asbestine (magnesium silicate), diatomaceous silica,
amorphous and crystalline silica, micaceous materials, barium sulphate, Whiting and pumices.
The following natural resins and some of their glycerol esters may be utilized as ingredients of the non-volatile portions of the binder: rosin,
`rosin ester, Congo, Congo ester, Manila, Manila ester, dammar, sandarac, mastic, pontianac, East India, kauri, and shellac. `The following synthetic resins may also be used: glycerol phthalate, ethylene glycol phthalate, pentaery-thritol phthalate, vinyl acetate polymers, phenol formaldehyde condensation products, modified phenol formaldehyde, formaldehyde resins, para coumarone-indene (cumar) resin, chlorinated di- -phenyl resin, and cyclo hexanone formaldehyde resin.
The non-volatile proportions of the binder may also include the following drying and semi-drying oils which are of vegetable or animal origin: China-wood oil, refined linseed oil, linseed oil (kettle bodied), menhaden oil, oiticica oil, poppy seed oil, castor oil, sardine oil, soya bean oil, and
A sunflower oil.
The volatile proportions of the binder may comprise one or more conventional thinning agents or solvents or one or more of those seing ingredients in the proportions set forth:
Gallons Pigment 2.0071 Oils 1.4010 Resins 0.7000 Volatile, solvent 3.50
The signicance of the relation between the wet film thickness of the binder as it is applied to the surface to be marked and the size of the autocollimating units will be appreciated by i referring to Fig. 3 wherein autocollimating unit 20 of a diameter S is partially embedded in the wet film 2i. It is essential that a portion of the autocollimating unit 20 be exposed in order to effect the desired reux reection and simultaneously it is important that the binder engage sufilcient'area of the sphere to insure a tenacious grip. Accordingly, the wet lm 2| is illustrated as having a thickness of from 0.40 to 0.70 times the size of the autocollimating unit and is denoted as W or wet film Athickness which schematically corresponds to the level of the jacent the embedded autocollimating unit 20 will be of a thickness W as explained above and the remainder of the dry film 22 will substantially correspond in thickness to the level within the y bucket I9. illustrated in Fig. 4, from which the volatile portion has evaporated and will be approximately from 0.44 to 0.70 times the wet film thickness W, which dry film thickness is denoted as D. It has been found in practice that the dry lm thickness profile 22 incorporates cuDS" about each autocollimating unit 20 which may be due to capillary attraction, surface tension, and the like. The remainder of the dry lm prole substantialaiy corresponds to the nonvolatile content of the binder. These proportions relating to the size of the autocollimating unit, the .dry lm thickness, and the wet film thickness are critical and if deviated from, the resultant marker may be grossly decient in reecting characteristics, durability, or both.
In the above description of the physical proportions of the binder, a simple classication into volatile and non-volatile portions has been made. A further analysis of the non-volatile portions of the binder is of great significance in the fabrication of markers comprising binders and autocollimating units such as relatively small glass spheres. The non-volatile portion generally comprises pigment 23 and non-volatiles 24 exclusive of pigment. These latter ingredients generally comprise oils and resins in addition to pigment 23, see Fig. 6.
- In order to provide a combined marker of binder and autocollimating units capable of long life, it is essential that the autocollimating units be held as tenaciously as possible for the life of the marker depends from the presence of the autocollimating units to prevent direct wear of the marker by vehicular trame or otherwise. To impart the quality of tenacity to the binder, it is essential that the quantity of pigment'be less than one-half by volume of the total quantity of non-volatile ingredients. It is to be remembered 1 that the pigment is essential if reilectionis to be effected and that if too little pigment is utilized the proper reection desired will not result and furtherl that if more than one-half of the total non-volatile content of the binder be pigment then the combined marker' will be critically short-lived as indicated by the abraiding test,
the results of which are set forth in the table in Fig. 7 wherein a series of eight markers were rated. Each sample tested was rated after twenty-six thousand revolutions of then machine by dividing the final area of markers remaining by the original total area and multiplying the fraction by one hundred. The curve in Fig.
'I corresponds to this table and clearly depicts the critical nature of the ratio oi the pigment portion to the remainder of the non-'volatile content of the binder. For example those marker samples which incorporated more than flity per cent pigment by volume in the non-volatile portion of the binder obtained an extremely poor abraidlng rating; see the test data on sample number wherein 51.3 per cent of pigment was utilized and an abraiding ration of twenty per cent resulted, whereas samples number 2, 6 and 8, each of which contain a pigment ratio of less than fifty per cent achieved an abraiding rating of one hundred per cent.
In order to improve the life characteristics of the combined marker not only is it essential that lresins is important. Combined markers of the type described may be subjected to vehicular traillc and accordingly the quality of toughness is desirable. In general the greater the quantity of resins present in the binder, the greater the toughness of the finished marker. The use ci too much resin however will result in a brittle marker which will soon crack and deteriorate. Accordingly, it is desirable that the binder be flexible to prevent cracking and be capable of withstanding temperature changes, atmospheric conditions, and the like. In general, the presence of oils within the binder will impart the desired characteristic of flexibility. The skillful proportioning of oils and resins within the nonvolatile portions of the binder will result in a composite marker including autocollimating units and binder which is capable of withstanding vehicular traic, changes in atmospheric conditions, shock, and in general capable of long life which is of great importance as the cost of the marker is generally higher than those consisting simply of paint, but if the composite marker is inherently capable of relatively long life, the cost of the superior marker per period of time may be the same as the inferior marker or even less.
It has been found that an oil length of from five to seventy-five gallons imparts the above described desired characteristics to a composite marker in accordance with the invention. The ratio of oil to resin is expressed in terms of oil length which may be defined as the ratio of oil in gallons to each one hundred pound unit of resins. The particular oil length selected for the composite marker may be varied within this range depending upon the particular time for drying which is to be allotted to the marker. In general, when a quick dry is necessary, a lesser oil length is utilized with corresponding less flexibility imparted thereto. When great flexibility is desired a greater oil length is utilized and a correspondingly longer time for drying of the marker must be reckoned with. When longer oil length corresponding to greater ilexibility is desired and only a relatively short time can be allotted for drying, the oil selected should be of the faster drying type such as China-wood oil, oiticica oil, and perilla oil. When great toughness is to be incorporated in the finished marker, a relatively large portion of resins is utilized and to nevertheless impart good flexibility characteristics, the slower drying oils :are included such as linseed oil, soya bean oil, or ilsh oil. The exibility characteristics of the composite marker are not to be ignored if long life is to be assured, for the autocollimating units are substantially rigid and are subject to extreme loading and shock which will cause their dislocation unless the binder be sufficiently flexible.
In the fabricating of road striping it is sometimes of primary importance that the finished marker be applied to the road surface a very short time before theroad is opened for normal traiilc. Under this condition it is essential that the marker dry in a very short time and nevertheless have flexibility characteristics. While these qualifications are normally relatively incompatible yet the desired results may be effected if a synthetic phenolic resin be utilized. When this ingredient is incorporated in the nonvolatile portion of the binder, a finished road surface traflic marker of short oil length may be eiiected having remarkable film strength, which under extreme shock and other loading, results in supercial chalking rather than checking. This superficial chalking is desirable as it makes for good reflection in the day time. These concentrated phenolic resins of the oil soluble type are alkali and Water resistant, capable of great durability, generally tough and very resistant to wear. The following physical and chemical proportions are associated with these phenolic resins:
Specic gravity L19 to 1.22 Melting point F 195 to 225 Aside number to 105 These synethetic phenolic resins contain no rosin, ester gum, oils or any other diluting ingredients and act diierently from that usually expected oi rosins and the characteristics of flexibility so essential to a combined marker incorporating autocollimating units is inherent and accordingly the combined marker incorporating these ingredients are ideally suited for conditions necessitating the characteristics of quick drying, toughness, flexibility and durability.
Whereas the physical proportions or sizes of the autocollimating units have been related to wet and dry film thickness of a reflecting binder in a composite marker, it is to be understood that smaller autocollimating units may also be included. For example, whereas autocollimating units such as glass spheres of a diameter of 0.030 may be incorporated in a reiiecting binder having a wet lm thickness of 0.020" and a corresponding dry lm thickness of 0.010" to give desired reiiecting characteristics and durability, yet additional smaller autocollimating units such as glass spheres ranging in diameter from 0.005" up to 0.030" in diameter more or less may be partially or completely embedded in the binder iilm together with the first mentioned units of a diameter of 0.030". Such finished markers having autocollimating units of various sizes incorporated in their binder yield exceptional long life characteristics as after very long continued wear successively smaller autocollimating units come into play as the binder becomes thinner and some of the larger units becoming dislodged. Such a marker has a high initial reflecting efficiency and continued high reecting efliciency throughout its exceptional long life.
To effect a satisfactory marker comprising a reiiecting lm and la series of autocollimating units, the lwet and dry film thickness may be related to the largest size units or the generally predominating size units. In different markers,
that various changes may be made in this deproper lm will be correlated to a predetermined.
In order that the finished marker have the proper reflecting characteristics each autocollimating unit should have a portion of the reecting binder thereabout and beneath. As the autocollimating units are incorporated within th binder before the latter has dried, it is essential that the time of application of the autocollimating units to the binder be correlated with the drying time or if this time of application be fixed, itis of great importance that the drying time of the binder be predetermined as above described. Not only may the drying time be effected by varying the proportion of the oils within thev non-volatile portions of the binder but it may be generally stated that the greater the non-volatile portion the quicker will be the drying and accordingly if the balls are applied when the binder is very wet, it may be best to to what is shown in the drawing and described in the speclcation but only as indicated in the appended claims.
4What is claimed is: l. A combined highway and center line comprising a road surface, a reflecting binder and a series of relatively small glass spheres ranging in diameter from .005 inch to a .030 inch, said spheres being arranged in said binder in partially embedded relation, said binder having a wet nlm thickness of from-.40 to .70 times the generally predominating largest spheres size and a dry film thickness of from .44 to .70 times the wet lm thickness, whereby the spheres will be held tenaciously within the reecting binder and a minimum of binder utilized commensurate with durability, said binder having a non-volatile portion and a volatile portion, said non-volatile portion including a reflecting pigment and a synthetic phenolic resin, the ratio by volume of pigment to the total non-volatile portion being less than 50 per cent.
2. A combined highway and lane line comprising a road surface, a reecting binder thereon comprising pigment, non-volatile oil, and resin, and a series of autocollimating units partially embedded in said binder, the ratio by volume of pigment to pigment, non-volatile oil, and resin being less than 50 per cent.
3.1The structure recited in claim 2, the nonvolatile portion of said binder being approximately in the following volumetric proportions:
use less volatile ingredients to insure a reflecting Pimm* Gllg iilm beneath the autocollimating units. N- l tf1 .l 1'4010 It will be obvious to those skilled in the art Rggi'rfo a l e 01 011000 vice without departing from the spirit of the invention and therefore the invention is not limited LEROY SHUGER.