US 2648861 A
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Aug. 18, 1953 K.\v.\.|-|ARDMAN ETAL BRUSH ANDl METHOD OF MAKING Filed April 13, 1949 Mm@ n mmh N Nd m Eff. 7 Vd r mHr a /u M @n f H Patented Aug. 18, 1953 BRUSH AND METHOD F MAKING Kenneth V. Hardman, Upper Montclair, and Arthur J. Lang, Cedar Grove, N. J., assignors to H. V. Hardman Company, Inc., a corporation of New Jersey Application April 13, 1949, Serial No. 87,186
1 This invention relates to a brush and the method of making it. The invention relates particularly to the setting of synthetic bristles within a ferrule so that the butts of the bristles, the ferrule and the cementing composition become integral in the curing of the cementing `l4composition, and do not shrink away from each other as the cured product cools.
The application is a continuation in part of .our copending application Serial No. '75,856 filed 1949 for Bristle Setting,
due to the fact that the coefficient of expansion on heating or shrinkage on cooling is at least several times as large for the synthetic bristles as for the metal of the common ferrule.
In using nylon bristles, for instance, we have endeavored in early experiments tocorrect for the shrinkage of the cemented bristle butts away from the ferrule on cooling subsequent to curing the cement. We have coated the bristle butts within a metal ferrule with the cementing composition and cured in usual manner; after the curing and cooling, We have replaced the ferrule by a smaller one which fits tightly around the now shrunken cemented bristles. This expedient is obviously inconvenient and has proven unsatisfactory.
The present invention relates to a bristle setting in which the whole assembly, including the `bristle butts themselves, the surrounding ferrule and the cementing composition become integral and in which there is no separation of the cemented bristles from the ferrule as the product is cooled subsequent to the heating step to harden the cementing composition and in which a resilin which the ferrule and the synthetic bristles used are soluble in a common solvent and in which the bristles are united integrally together Aand also to the inside of the ferrule by treatment with such common solvent. In one embodiment the invention comprises such brush vin which the ferrule is constructd of plastic -material having the same or a higher tempera- 2 l ture coeiiicient of expansion (and thereforeof shrinkage on cooling) than the material of the bristle butts so that, as the assembly is cooled after the heating step, the ferrule shrinksat least as much in proportion as the bristles themselves and adheres tightly around the exterior Voi? the bristle assembly. In the preferred embodiment, the invention comprises also the useof the cementing solvent in limited proportionithe proportion must be adequate only to wet the exterior surfaces of all of the bristle buttsuand the portion of the ferrule surrounding the bristle butts, but inadequate to convert them by solvent action to a flowable mass. In such proportion the solvent becomes a part of the solid material and remains xed either in the form of a new chemical compound or as a solid solution in the finished cemented assembly of the bristleswithin the ferrule.
The invention comprises also the herein described method of making a. brush of the kind described.
The invention will be further illustrated by description in connection with the attached drawing to which reference is made. v
Fig. 1 is a plan view of the improved brush, partly broken away for clearness of illustration.
Fig. 2 is a sectional view on line 2--2 of Fig. 1.
Fig. 3 is a sectional view on line 3-3 of Fig. l.
There are shown ferrule l0, bristles I2 in an assembly packed at the butt ends within the ferrule, and spacer strips I4 extending in spaced relationship to each other through the bristle assembly so as to space the bristles at their butt ends into layers. The bristle butts are adhered in the zone l5. There are shown also the cap I6 extending over the tips of the bristles in the final assembly and conventional handle I8.
The thickness of the cap is exaggerated for the purpose of illustration. The solvent for the bristle butts and ferrule referred to later herein is not shown in the drawing for the reason that the solvent is not visible in the finished assembly.
The bristles used in our invention may be the commercial synthetic laments which are sold` as a substitute for hog bristles as, for instance., tapered nylon, cellulose acetate, cellulose acetate: butyrate, methyl methacrylate, polyvinyl or, polyvinylidine chloride iilaments. It will be understood that the synthetic bristle selected should be one which is suitable for the use to which the brush is to be put. For a paint brush, for instance, the lament selected should be one that is not soluble in the paint oils. For a lacquer the lament should be insoluble in th com- .mon lacquer solvents. The nylon and the various plastic vinyl compounds in bristle form have .the widest applicability because of resistance to a wide variety of solvents.
The ferrule is constructed of any one of the compared to the range of cooling of the solid coated bristle butts. The ferrule stretches if necessary to accommodate itself to the dimensions of the interior of the assembly.
The invention Wil be further illustrated by detailed description in connection with the following specic example of the practice of it.
Example The nylon bristle pack is inserted in the nylon ferrule. The pack is then sized out to the depth of adhesion required, as for instance inch. A mixture of m-paracresol is then sprayed over the surface of the butt ends and inside the ferrule. The amount of this cresol sprayed is 1.8 g. for the bristle assembly for a 4 inch .paint brush. Following the application of the cresol mixture, the capping is applied. This consists of a solution of nylon in m-paracresol. Application may be made either by pouring or spraying. The quantity used is approximately 1.5 to 3.5 cc. for a brush of the kind described. All applications are made with the bristle butts in an upright position.
Following the capping procedure the brush is placed in an oven at an air temperature of 275 F. for a period of 7 minutes. At the end of this time the brush is removed and cooled. Prior to cooling care must be taken not to bend or in any Way damage the Warm nylon bristles.
Brushes made as described show no separation of the ferrule from the bristles or separation of the bristles from each other or from the spacer strips.
Special advantages are found in our product. It is not necessary to insert fasteners through the ferrule and bristle assembly. It is unnecessary to have a wide zone of cementing. In conventional brushes, it would be necessary to make certain tht the bristles are united at a level below that of later insertion of the fasteners either by drilling or driving or both; otherwise there would be loosening of bristles below the point of adhesion so that they would fall from the brush. In our new product it is not necessary to extend the zone of union of the bristles to any particular level so long as they are firmly united at their butt ends. The brushes are durable in use and their manufacture is certain and dependable.
It will be understood that it is intended to cover all changes and modifications of the example of the invention herein chosen for the purpose of illustration which do not constitute departures from the spirit and scope of the invention.
What We claim is:
1. In setting synthetic bristles tightly Within a ferrule, the method which comprises assembling thermoplastic bristle butts in uncoated condition within a thermoplastic ferrule having a temperature coeicient of shrinkage at least equal to that of the plastic of the bristle butts. applying over the assembled butts a owable solvent for the bristle butts and for the ferrule, the solvent being substantially non-reactive chemically with the plastic bristles and ferrule, forming therewith solutions that are ilowable at elevated temperatures and hard When cooled, and being added in quantity adequate to Wet all the bristle butts and the inner surface of the surrounding portion of the ferrule but less than sufcient to dissolve completely either one thereof, then warming the solvent treated assembly to the temperature of softening of the exteriors of the butts and ferrule by the solvent, and then cooling the resulting product to room temperature, so that the softened material hardens and the ferrule and bristles are united in an integral structure.
2. The method described in claim 1, including Warming the ferrule to a temperature substantially above that of the bristle butts so that. in the said cooling, the ferrule cools through a greater range of temperature and, in the cooled product, is in stretched tight condition around the bristle butts.
3. In setting synthetic bristles with a ferrule, the method which comprises assembling nylon bristle butts in uncoated condition within a nylon ferrule, applying over the assembled butts a liquid solvent for the bristle butts and the ferrule, the solvent being added in quantity adequate to wet all the bristle butts and the inner surface of the surrounding portion of the ferrule but less than sufficient to dissolve completely the bristle butts or the ferrule, then warming the solvent treated assembly so that some material of the bristle butts and ferrule is softened by the solvent, and then cooling the resulting product to room temperature, so that the bristle butts and ferrule are united in an integral structure.
4. The method described in claim 3, the phenolic solvent being a cresol.
5. The method described in claim 3, the said solvent being a phenolic solvent and the temperature of said warming being about to 325 F.
6. The method described in claim 1, including applying a thin layer of solution of the material of the bristle butts in the said solvent as a cap over the solvent-treated bristle butts before the said warming and then effecting the warming and subsequent cooling, so that the cap, bristles,
and ferrule become integrally united.
7. The method described in claim 1, the ferrule being warmed to a substantially higher tempera-ture than the interior of the bristle assembly so that the ferrule shrinks over wider range of temperature on cooling than does the bristle assembly, the ferrule and the bristles being composed of the same plastic material.
8. A brush comprising a handle, a thermoplastic ferrule, thermoplastic bristles packed at their butt ends tightly within the ferrule and material which is a solvent for the bristles and ferrule when heated and a solid at ordinary temperatures extending as a cement between the bristle butts and the inner surface of the surrounding portion of the ferrule and bonding the bristle butts and ferrule in an integral structure.
9. A brush comprising a handle, a nylon ferrule, nylon bristles packed at their butt ends tightly within the ferrule, and nylon cement adhering the bristles at their butt ends to each other and to the inner surface of the surrounding portion of the ferrule, so that the whole is an integral structure.
KENNETH V. HARDMAN. ARTHUR J. LANG. f
References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 709,610 Schreiner Sept. 23, 1902 1,238,635 Chandler Aug. 28, 1917 1,477,706 Karl Dec. 18, 1923 2,303,800 Swann Dec. 1, 1942 2,341,823 Smith Feb. 15, 1944 2,363,685 Neuschaefer Nov. 28, 1944 2,400,809 Cave May 21, 1946 2,406,732 Hardman Aug. 27, 1946 2,512,997 Bxler June 27, 1950