US2218909A - Method of making reflecting devices - Google Patents

Description

Oct. 22, I940; E. GILL, J'R 2 9 METHOD OF MAKING "REELECTING DEVICES- Filed March 30, 193

INVENTOR ATTORNEYS I lfaw/A/ 36/44/51 Patented Oct. 22. 1940 -UNlTED STATES PATENT OFFICE METHOD OF MAKING REFLECTING DEVICES Edwin R. Gill, Jr., Yonkers, N. Y.,.assignor to Prismo Holding Corporation, New York, N. Y., a. corporation of New York Application March 30, 1937. Serial No. 133,788 I 1 Claim. ('01. 88-105) This invention relates to the manufacture of reflectingdevices, including signs when that term is used in its broadest aspect and includes any marker, signal device or mechanism which may be employed to attract attention or convey information, and irrespective of whether they may be in the form of I independent units or constructed upon an already existingbase, such as a wall, a pavement, etc., and has specialrefer- 0 ence to signs of the kind employing reflex reflecting elements forming the subject matter of an earlier invention of mine for which U. S. Letters Patent No. 1,902,440 were issued on March 21, 1933, and with respect to which the present invention constitutes in part an improvement.

I have discovered that in the construction of such signs, particularly when under circumstances where .there is not the opportunity .to use a baked enamel as a binder for glass reflex reflecting elements as, for instance; where the sign or marker has to be constructed in situ as.

on the pavement of a highway, or where for any other reason it is inconvenient to use a baked enamel and an air drying paint or enamel has to be used, a more close and permanent bond between the reflex reflecting elements and the.

binder, in a way that will preserve the sign for a longer time from wear anddisintegration, may

be obtained by a novel and improved form of such signs and methods of making it which involve making the reflex reflecting elements out of plas-'- ticmaterial of the kind known as synthetic resin, such as theformaldehyde phenolic resins, forv maldehyde urea resins, glycerine resins, or the like, whether of the condensation type or of the polymerization type, and embedding them in a v will reflect light in a direction parallel to the in- V cident rays and which has improved optical characteristics.

Another object of my invention isto provide a method'whereby in such a device both the reflex reflecting elements 'andthe binder in which they are embedded will form an integral mass, .30 thus possessing an advantage over a reflecting device or reflex reflectiyesign composed of glass spheres embedded in a reflective binder of ordinary air-drying painter enamel; The respec tive cceflicients of expansion 'of glass and such 55 air-drying paints and enamel are usually diflerent and where such a sign is subject to the varying degrees of temperature due to changesof weather, the composite structur will have a tendency to become weakened and the binder to separate from the spheres and permit them ulti- 5 mately to work loose.

Other objects and advantages of my invention will appear from the following description of it and by reference to the accompanying drawing in which: 10

Fig. 1 is a plan view of a sign embodying my invention.

Fig. 2 is a cross sectional view greatly magnified of a portion of the sign shown in Fig. 1.

Fig. 3 is a cross sectional view of such sign con- '16 structed upon the urface of a highway.

Fig. 4 is a sectional-view of a mold for making spherical reflex reflecting elements of plastic material. p Y

Fig. 5 is a sectional view of an improved form 20 of a reflex reflecting element.

Fig; .6 is a sectional view of the reflex reflecting element shown in Fig. 5 mounted in a perforated base. 7

Fig. 7 is aside view of the reflex reflecting ele- 25 ment shown in Fig. 6.

Referring to the drawing in which the same reference numerals are used to designate similar parts, I is'a base which may be of any suitable. material adapted to provide a supporting 30 .surface for the other materials out of which the sign is made, and where the sign is an independent unit (Fig. 1) it may be preferably of itself, such as concrete, of which the upper surface of the highway is composed Upon this base is delineated any desired'insignia by the application thereto of a binder coat 2 of paint, 40

lacquer or other fluid substance containing avarnish gum capable of integrating by polymerization or hardening with the synthetic resin particles thereafter to be applied. Said varnish 1 gum is of the same or similar resin out of which the reflex reflecting. elements are madeand if said varnish gum is of the permanently soluble class, such for instance as depolymerized formaldehyde-phenolic resin, it may be either of the alcohol-spirit soluble classification or of the benzine-oil soluble classification. Liquid resin itself may be used. Said coating may be made in any desired color by the addition of suitable pigment provided it is reflectiveof light. 7 v

Before this coat isdry and while it is still soft, there is spread upon it a layer of reflex reflecting elements consisting of minute spherical transparent particles 3 composed of a synthetic resin such as phenol-formaldehyde or ureaformaldehyde more or less completely polymerized which are embedded in said coat to a depth of approximately one-half their diameter." The spheres will have a tendency to become embedded in the coating as alresult of gravity, capillary attraction or such embedment may be accomplished either by hand or by the use of a roller or other suitable means. It is important that the spherical particles be as small as possible and lie close to each other so as to avoid any dark or dead spaces in the surface of the insignia and to refract and reflect as much light as possible. r

As the said binder coat hardens it will unite withthe embedded portions of the spheres and upon completion of the hardening process the binder and spheres will have become completely united together in an integral mass. I have found that where the said binder coat is compounded so as to produce a paint or lacquer of normal brushing consistency the extent of its reaction on the embedded surfaces of the spheres will in no way diminish their reflex refracting quality and will only result in producing a per manent bond or weld between the spheres and the binder coat. The spheres may be colorless and the reflective binder may be white or given a desired color or the spheres themselves may be given any desired transparent color. An additional protection against the moisture and the elements may be given to the sign by coating the finished sign with a protective transparent waterproof coating such as a transparent lacquer, varnish or other like substance.

These minute spherical particles composed of synthetic resin may be manufactured in any appropriate way either by using a ground synthetic resinin the form of a molding powder which may be charged into polished metal dies in a proper molding press or they may be cast from liquid synthetic resin in a mold such as is shown in Fig. 4 in which the two halves 4 and 5 composed preferably of glass are each "formed on their contacting faces with a number of hollow hemispheres 6 and 1 communicating with each other by small passages 8. When the two halves of the glass mold are put together with the-hollow hemispheres opposed the spherical spaces and the passages between them may be filled with the liquid synthetic resin through the tube 9,

-- the displaced air escaping through the vent Hi.

- -The particular advantage involved in making 6,the spheres, which function as spherical lenses,

out of synthetic resin is that the focal point of the lens can be definitely fixed on its surface where it is embedded in the light reflective binder. The position of the focal point of any sphere is dependent upon the'index of refraction of the particular material out of which it is made and will be located on the surface when theindex of refraction is 2.0. 'Where the reflective coating is on the surface of the sphere as in such refraction should be as .close to 2.0 as possible but this is not feasible with glass except at a costwhich would make it prohibitive commercially whereas by making the spheres out of synthetic resin the index of refraction can be easily and cheaply controlled and fixed definitely at 2.0 by the addition of suitable salts to the solution when it is being compounded. A

In Fig. 5 I have shown a novel and eificient form of a reflex reflecting element formed out of transparent synthetic resin and adapted to be used and form an integral part with a'binder paint or enamel containing a varnish gum capable of integrating by polymerization or hardening with the synthetic resin of said elementsas above described. This form of reflex reflecting element contains wholly encased within itself, however, the reflective material consisting of a spherical mirror. The upper and outer portion I2 of this reflex reflecting element is in the form of a spherical lens equal in size to a complete hemisphere while the lower portion index of 2.0 the said mirror will be constructed 1 on the same radius as that of the spherical lens l2 and its distance from the outside surface of the said spherical lens will be equal to the diameter of said lens, but where the synthetic resin has a refractive index of less than 2.0 the said mirror will be positioned a slight distance further away and will be constructed upon a proportionately longer radius.

These reflex reflecting elements are constructed as follows: The stud l5 which may be of any suitably strong material having approximately the same coeflicient of expansion as the synthetic resin out of which the element is to be made or may be preformed of the same synthetic resin, is mounted in an upright position and to its end is fastened by a suitable adhesive substance, the thin metallic spherical mirror l4 silvered in the usual way on its concave side, after which a quantity of transparent synthetic resin is molded about the mirror and said stud in the form above described by any suitable wellknown means or method, the lower end of the.

stud l5 being utilized to hold the mirror H in produced a reflex reflecting element in the form of a spherical lens having encased within it at the focal surface of said lens a reflecting surface wholly protected from the atmosphere. These reflex reflecting elements should be preferably made in a size as small as possible and, after removing the protruding portion of the stud l5 whereby it was held in position in the mold, a plurality of them may be arranged close to each other-with their hemispherical surfaces uppermost to form the indicia of a sign and with their lower cylindrical portions embedded in a layer of wet paint, lacquer or other substance as a binder material upon a supporting background, which binder material contains a varnish gum capable'of integrating with the synthetic resin out of which said'reflex reflecting its-proper position in the mold. There is thus elements are made, and as has been hereinbefore described, the said binder in a similar way will completely unite with the cylindrical portions of the elements embedded in it so that when the said binder has hardened they will be completely united with the said binder in an integral mass. When formed in larger sizes the protruding portions of the studs may be left in place and provide means for affixing said elements to a supporting background either by inserting them with a tight flt into perforations in the background support or byproviding them with a thread whereby they may be screwed into the background support.

In Figs. 6 and 7 I have shown this same reflex reflecting element equipped with'novel means for mounting it in a hole provided for that purpose in a supporting base consisting of a plate I6 of sheet metal or the like, the surface of which may be enameled in any suitable colors and in a form to constitute a sign. The reflex reflecting element is molded in the same way but with an annular bead l1 surrounding its outer periphery substantially at the plane of division between the hemispherical portion 12 and the cylindrical portion l3 of said element. The bead 'l'l forms a stop to limit the'movement of the element through the hole in'the plate l6.

- portion 13 are two ears I9 made of flat spring metal suitably disposed about said wall. Said ears are each formed with lower diagonal edges 20 and upper diagonal edges 2| and are curved or bent outwardly as shown in Fig. 6. The said reflex reflective element may be forced through a round hole inthe plate l6 substantially the same size as the cylindrical portion l3 and as the said element is forced into the position shown inFig. 6 the ears l9 will first be depressed and will then spring outward and engage the rear side of the plate 16. It will be noted that the upper edges 2| are inclined to the surface of the plate and curve outwardly, so that despite variations in the thickness of the plate 16 the ears will engage the plate and hold the reflex reflecting element more or less rigidly in 'place.

It is obvious that many modifications may be made without departing from the spirit of my invention. For instance, the background may be covered with the reflex reflecting elements leaving the insignia with'a plain flat surface, or the entire surface of the sign may be covered and contrasting colors used to differentiate the insignia from the background.-

What I claim is:

The method of making a reflecting device composed of a plurality of transparent, reflex reflecting elements partially embedded in an opaque light reflecting background substance which comprises applying to a base a layer of plastic, opaque, light reflective binder material containing a varnish gum of synthetic resin capable of integrating by polymerization with synthetic resin elements subsequently to be applied, partially embedding in said layer a plurality of reflex reflecting elements of such a synthetic resin, and substantially permanently joining the elements to the layer by polymerization of the varnish gum in the background layer.

. EDWIN R. GILL. JR.

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