US 3386119 A
Description (OCR text may contain errors)
June 4, 1968 s. M. SHULMAN .3,386,119
I PAINT BRUSH AND METHOD OF MAKING THE SAME Filed March 2, 1967 INVENTOR. ST UART M. SHUL MAN ATTORNEY United States Patent O "ice 3,386,119 PAINT BRUSH AND METHOD F MAKING THE SAME Stuart M. Shulman, New York, N.Y., assigner to Baker lylrusll Co. Inc., New York, N.Y., a corporation of New Filed Mar. 2, 1967, Ser. No. 619,999 Claims. (Cl. 15-193) ABSTRACT 0F THE DISCLOSURE This invention relates to an improved paint brush or the like of the multiple component type including a tubular ferrule, a bristle knot and a handle, and to a method of making the same. The space within the ferrule, between the bristle knot and the handle, is filled with a light-weight, closed cell, expanded, foamed resinous material, which material completely seals the interior of the brush against the ingress of solvents, paint and the like.
In accordance with the method, the pressure developed by lthe expanding resin forces increments of the foamed plastic into all the interstitial spaces leading to the interi-or of the ferrule, thus sealing the interior without appreciably adding to the weight of the brush.
In accordance with an embodiment of the invention, the foamed plastic serves the additional function of anchoring the handle within the ferrule.
Summary of the invention In the past, paint brushes have been made by a variety of pr-ocesses, most of which contemplates providing a tubular ferrule open at both ends. A bristle knot is secured within one en-d of the ferrule by any of a variety of known methods, including, particularly, temporarily supporting the bristle ends in the ferrule and thereafter covering the ends within the ferrule with a cementitious mass in liquid form, which mass, when cured, seals the end and permanently supports the bristles in the ferrule. Thereafter, the handle having a bottom portion corresponding as nearly as possible to the inside diameter of the ferrule is inserted into the ferrule and secured therein, usually by nailing. The ferrule itself is generally formed of a strip of metal bent to tubular configuration, the marginal edges of the metal being rolled over on themselves to define a seam of the ferrule.
It has been disc-overed that such brushes have the drawback of permitting liquids such `as solvents to be admitted into the void within the ferrule defined between the lower end of the handle and the upper end of the bristle knot. The admission of moisture results from the fact that even the most carefully constructed brush of the sort described incorporates interstitial spaces leading t-o the interior of the ferrule, such spaces existing predominantly between the brush handle and the ferrule but often and additionally within the seam of the ferrule itself or, more rarely, between the ferrule and the bristle knot. When a brush having such spaces and void is used and immersed too deeply into paint, increments of paint are admitted to the interior of the brush. In cleaning the brush after use, the same may be immersed in a solvent to a level above the junction between the ferrule and the handle, whereby considerable increments of lthe normally lower viscosity solvents may be admitted to the interior of the ferrule.
When a brush subjected to such treatment is subsequently used, solvents, paints or combinations thereof which 3,386,119 Patented June 4, 1968 may have collected within the interior of the brush will run down the handle, where the brush is inverted, or onto the bristles, causing discomfort to the user and possible contamination of the surface being painted.
By the present invention, the brush is formed by a method which includes depositing within the ferrule, `between the bristle knot and the handle, a quantity of expandible resinous material. The resinous material, after insertion of the handle, is caused to foam and drastically increase in volume to the point where the interior of the ferrule is filled with a closed cell resin structure which is essentially impervious to solvents, etc. Additionally, the pressure of the expanding resin causes increments thereof to fill any interstitial spaces leading to the interior of the ferrule.
In accordance with the preferred embodiment, the portion of the brush handle disposed within the ferrule is provided with a mouth having converging wall portions, which mouth is filled by the expanding foam composition and, due to the dove-tail configuration of the walls defining the mouth, the foaming plastic, after cure, functions to lock the handle to the ferrule,
Reference will now be made to the accompanying drawings, forming a part hereof, in which:
FIGURE 1 is a side elevational View of a brush in accoi-dance with the invention;
FIGURE 2 is a sectional view of a sub-assembly of a brush in accordance with the invention;
FIGURE 3 is a magnified vertical section taken on the line 3-3 of FIGURE 1 at an intermediate stage in the fabrication of the brush;
FIGURE 4 is a section similar to FIGURE 3 showing the completed brush.
In accordance with the invention, a brush 10 includes a tubular metal ferrule 11 formed of an extended strip which has been bent to the desired tubular conformation and the ends of which have been rolled and liattened to form an edge seam 12.
As best seen in FIGURE 2, a bristle knot 13, including tufts of bristles 14, the upper ends of which are integrated by a solidified mass of cementitious composition, such as epoxy 15, is supported in the lower end 16 of the ferrule. It will be understood that the bristle knot 13 may be formed and thereafter integrated into the lower end 16 of the ferrule or the bristles may be temporarily supported within said lower end, as by wedges (not shown) and the epoxy mass 15 poured over the bristle ends, the knot thus being formed within the ferrule.
The vari-ous means of supporting and forming the bristle knot are well known and are beyond the scope of the present invention.
In accordance with the present invention, a quantity of resinous material 17 incorporating a blowing or foaming agent is disposed -within the area above the bristle knot 13. While a multiplicity of satisfactory formulations are available, a preferred formulation is a foamed, gasexpanded, pour-in-place urethane resin supplied by the Nopco Chemical Company of Newark, NJ., the formulation preferred being identified by such organization as Formula #106. This formulation comprises a two part mixture which is compounded just prior to use.
Technically, the starting mixture comprises diisocyanates which are reacted with comparatively low molecular weight polyols containing active hydrogens. The reaction produces two 'basic processes, namely, formulation of a polymer by the above reaction and evolution of a gas to produce the foaming activity. The material, which is compounded just prior to introduction into the ferrule,
is supplied as a two component system, the components being designated, respectively, .as the R component and the T component. The R component is a clear, dark amber liquid of low viscosity containing the resin and a fluorocarbon blowing agent. Component T is a clear, light colored material containing the pre-polymer and the balance of free isocyanate.
An .additional description of a variety of suitable pourin-place urethane foaming compositions is contained in a booklet published by Nopco Chemical Company entitled Nopcofoam Pour-inplace Urethane Insulation, copyright 1961, the bookllet being identified as PSP-103-16.
The amount of mixed reactive R and T components introduced into the ferrule will, of course, depend upon the volume which mus-t be occupied by the expanded foam. This volume is a function of the cross-sectional area of `the ferrule and the spacing of the brush handle from the upper surface of the bristle knot 13.
In the illustrated embodiment, the handle 18, which may be formed of wood, is provided at its lower end with a downwardly directed mouth portion 19 which is defined by side Walls 20, 21, which walls converge in a -downward direction so that the mouth is essenti-ally dove-tailed in vertical section. The outer periphery of the handle is preferably formed to provide a tight frictional fit within the upper end 22 of the ferrule, the spacing between the side edges of the handle being exaggerated in FIGURES 3 and 4 for purposes' of illustration.
The handle is inserted into position directly after the batch 17 of mixed R and T components is disposed within the ferrule land prior to full expansion of said batch.
By Way of example only, and without limitation thereto, utilizing the polymer formulation above set forth, a brush wherein the Iferrule is 4 from side to side and about 1 from front to back, and wherein the l-owermost portion of the handle is spaced `from the uppermost surface of the epoxy mass 15 by a distance of about 3/8 and wherein the depth of the dovetailed mouth 19 is also about 3/8", a total of approximately 1%2 of an ounce of mixed R and T components is employed. The mixed components will begin to react slowly at ambient temperatures, the polymerization and liberation of gas progressively increasing in speed with the passage of time due to the exothermic nature of the polymerization reaction.
Preferably, the quantity of starting material is selected so as completely to fill the void defined within the ferrule after seating in position of the handle, the use of a slight excess of starting material being desirable so as to assure a pressure generated within the ferrule sufficient to cause minute veins of the foam to extend into all crevices or institial spaces S, S defined between the handle and the ferrule, the seam of the ferrule or elsewhere.
The foam material will Ibe fully set or hardened after about 24 hours and the brush will be ready lfor use. Where the brush is formed with a dove-tail or otherwise under-cut portion, the Ahardened foam will act firmly to anchor the handle to the ferrule,
It will be readily understood that the present invention is not limited to any specific formulation or formulations of foamed plastic material but may be used with any rigid, closed cell formulation which may be introduced into the interior of the brush and thereafter cause to expand.
While pouring an unexpanded starting mix and thereafter full expansion within the ferrule has been found to be the most convenient means of applying the foam, it will be understood that application by frothing will also be satisfactory. Frothing is a variation of the pouring method wherein the plastic mix is applied in a partially expanded state, the mixture ybeing thereafter permitted to continue to expand as in the pouring process.
As a means of comparison, in the pouring process the initial starting mixture will expand to about thirty times its original volume whereas in frothing applications, a four to one ratio is typical.
(The pouring application is preferred since greater pressures and greater foam density may be achieved than is the case with frothing.
If, for some reason, such as the existence of undue clearances between the parts or application of a considerable excess of starting materials, quantities of the foam are extruded through interstitial spaces, the extruded yfoam which projects beyond the outer face of the brush components may be easily removed either before or after full cure.
In practice, the cured, preferred urethane foam material has an extremely low density of from about 11/2 to about 51/2 pounds per cubic foot and, thus, does not add appreciably to the over-all weight of the brush. The preferred cured material is highly resistant to the absorption of water and does not dissolve or exhibit degradation in the presence of solvents normally encountered in painting operations. The material may soften `or swell slightly when subjected to some solvents, but this will have little or no lasting effect upon its original properties after the solvent is removed.
Of prime importance to the present application, however, is the fact that the interior of the brush will be rendered substantially impregnable to the admission of fluids to the interior thereof and, thus, it will not be necessary to take the usual precautions against immersing the entirety of the brush head in solvents for purposes of cleaning.
While the invention has been illustrated in conjunction with a preferred embodiment wherein the foam performs the double function of providing the sole or augmentative influence in uniting the handle to the ferrule as well as the sealing and void filling function, it will be readily appreciated that certain of the benefits of the invention may be attained where the lfoam does not perform any substantial handle retaining function.
Having thus described the invention and illustrated its use, what is claimed as new and is desired to be secured by Letters Patent is:
1. The method of manufacturing a paint brush or the like having a tubular ferrule, a bristle knot and a handle adapted to be frictionally supported in one end of said ferrule, said handle and ferrule, in the frictionally supported position thereof, having interstitial spaces defined therebetween, comprising the steps of introducing into said ferrule above said bristle knot la batch of foamable resinous material, interposing said handle into frictional engagement in the other end of said ferrule, thereafter causing said batch to expand by foaming, completely to fill the space within Said ferrule between said knot and said handle as well as to extrude through and fill said interstitial spaces.
2. The method of claim 1 wherein the portion of said handle within said ferrule defines a void having walls converging in the direction of said bristle knot and said foamed batch fills and void, thereby to lock said handle within said ferrule,
3. The method in accordance with claim 1 wherein said batch comprises a urethane resin.
4. A paint 4brush comprising a tubular ferrule, a subst-antially impervious plastic bristle knot supported within and sealing one end of said ferrule, said knot including bristle portions extending outwardly beyond said one end of said ferrule, a handle having an end supported in the other end of said ferrule, said end of said handle being spaced from said bristle knot, the lateral portions of said handle and said other end of said ferrule defining therebetween interstitial spaces, and a quantity of closed cell, rigid urethane foam within said ferrule, said quantity completely filling said space between said bristle knot and said end of said handle and said interstitial spaces, whereby said other end of said ferrule is sealed against ingress of liquid solvents and the like.
5. A brush in accord-ance with claim 4 wherein said end of said handle within said ferrule includes walls con- 5 verging toward said bristle knot defining a downwardly 3,263,259 open mouth and said foam completely fills said mouth, 3,281,882 there-'by to lock said handle against removal from said end of said ferrule.
References Cited UNITED STATES PATENTS 2,406,732 8/1946 Hardman 300-21 8/1966 Shulman 15--193 11/1966 Charvat 15--179 FOREIGN PATENTS 12/1955 Belgium. 10/ 1960 Great Britain. 2/ 1965 Great'Britain.
CHARLES A. WILLMUTH, Primary Examiner.
3,155,998 11/1964 Hardman et a1. 15-192 10 PETER FELDMAN, Examiner-