US 2426315 A
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Description (OCR text may contain errors)
L .MAR'ICK 2,426,315
STATIC FREE BRUSH Filed Sept. 25, 1943 INVENTOR. A 00/6 MAR/CK Patented Aug. 26, 1947 STATIC FREE BRUSH Louis Marick, Grosse Pointe Far-ms, Mich, as-
signer to United States Rubber Company, New York, N. Y.., a corporation of New Jersey Application September 25, 1913, Serial No. 503,756
provided with hair or fibrous bristles which arenon-conductors when dry, and when one of these .3 Claims. (CL 15 159) brushes is moved over a non-conducting surface a static charge may be produced upon the bristles and a static spark result. If a brush of this type is so used in places where inflammable materials are located, the brush may produce static sparks that will cause a fire.
Brushes provided with hair or other bristles which generate static electricity are used in munition factories to brush up small quantities of powder and when a static spark results it may cause a serious fire. A similar fire hazard is caused by the use of such brushes in various places where volatile gases are present.
The present invention contemplates brushes which will dissipate static electric charges or fail to produce such charges and as a result will not produce static sparks.
Static free brushes such as herein contemplated are well adapted for use in munition factories to brush up dry powder, in rooms where volatile gases are present, for brushing clothes or hair or for other uses where static electric charges would be objectionable.
A static free brush is produced in accordance with the present invention by depositing upon the bristles thereof a thin electric conducting coating such, for example, as a coating of conductive rubber or conductive resinous material, and by making the head in which the bristles are mounted and brush handle conductive so that a conductive path will be provided from the bristles to the head and handle to permit a static charge at the bristles to reach the hand of the person using the brush and disperse over his body.
The various features of the present invention will be further understood from the following description when read in connection with the accompanying drawing illustrating several brushes having the static free construction of the present invention.
In the drawing:
Fig. 1 is 2. pers ctive view of a paint brush of usual constructio kept for the static free feature of the present mvention;
Fig. 2 is a perspective view of a similar type of brush having an-electric conducting plastic head and handle;
Fig. 3 is a perspective view of a floor brush, and;
Fig. 4 is a perspective View of a clothes brush.
The brush shown in Fig. 1 of the drawing has a wooden handle ID, a metal ferrule or head I I and the bristle portion 12. Such a brush, of usual construction, may be purchased on the market and have the static free features of the present invention imparted thereto by dipping the'bristle portion 12 thereof in a solution of conducting rubber cement to thereby provide a conductive path along the bristles to the metal ferrule or head ll, and the handle I0 is readily made conductive by providing the same with the conductive coating It which obviously should contact the metal head ll so that a conductive path will be provided along the bristles to the head H and from the head along the handle to the hand of the person using the brush.
It is important that the bristles [2 be treated with a thin solution of conductive cement so that the conductive coating provided upon the-bristles will not appreciably increase the size or stiiiness of the individual bristles. Good results have been secured by dipping the bristles in a conductive rubber cement of the following formula:
Rubber Zinc oxide 15. Antioxidant 0.35 Accelerator 2.00
Stearic acid 7.00 Sulphur 0.75 Acetylene black 85 Such a cement is preferably thinned with gasoline to a. watery consistency. For example, good results have been obtained by employing a solution .of 769 grams of gasoline containing rams of touch, but is sumciently conductive to disperse static charges.
The mass of bristles I2 may be formed of various types of hair or of synthetic fibers or filaments such as rayon, nylon or otherplastics, all of which may be treated-by dipping them into the solution of conductive cement of the above example. The.
bristles l2 instead of being treated with conductive rubber such as above described may be treated with synthetic rubber, plastic or resin containing conductive carbon.
The wooden handle "I may becoated with a rubber composition such as given in the above example. However, for coating the handle portion of the brush it is deemed preferable to employ the conductive properties of acetylene black used as a varnish, lacquer or other synthetic resin coating. An example of such coating is as follows:
This coating may be applied to the brush handle by painting, spraying, or dipping and in the case of the brush shown in Fig. 1, it is important that the coating upon both the bristles and the handle be so applied that the coating shall reach or over-lap the metal ferrule of the brush so as to form a continuous conducting path from the bristies to the brush handle.
In the construction shown in Fig. 2 the brls-' tles I2 may be the same as the bristles 12 of Fig. 1 and may be rendered conductive by the treatment above described. These bristles, however, are shown as mounted in a plastic head It having formed integrally therewith the handle I5. The plastic material of which such head and handle are formed may be molded to the shape shown with the upper ends of the bristles l2 embedded in the head M. The head and handle may be formed of an electric conducting composition formed of hard rubber, phenol formaldehyde, methyl methacrylate, vinyl chloride acetate, polyvinyl alcohol and the like. A sufllcient amount of acetylene black is added to such compound to render it conductive so that a static charge created by the bristles l2 may travel along the head and handle to the hand of the person using the brush to dissipate such charge.
In Fig. 3 of the drawing there is shown a floor brush of the usual construction comprising the bristles I6, the head I I in which the bristles are mounted and handle 18 and both the head and handle may be formed of wood as usual. The bristles l6 may be rendered conductive by treating them the same as the bristles l2 above described, The head I! is preferably provided with a conductive coating l9 similar to the coating 13 above described and which should be so applied that it will form a conductive path from the upper ends of the bristles Hi to the handle l8, which handle i preferably given a conducting coating 20 similar to the coating l3 above described. When the fioor brush of Fig. 3 is so treated a conductive path will be provided upwardly along the bristles 16 to the head I! and along the handle l8 to the hands of the person using the floor brush.
In Fig. 4 of the drawing there is shown aclothes brush having the bristles 2| mounted in the head 22 which may be formed of wood or plastic material as heretofore, The bristles 2| are preferably treated similar to the bristles l2 to make them electrically conductive and the head 22 is preferably provided with a. conducting coating 23 which should be so applied that it will cover the top and side portions of the head 22 and contact the bristles 2| s that any static charge produced by the bristles may travel along these bristles to the head 22 and from the latter to the hand of the person using the brush.
The brushes above described have an electrical resistance varying from about 30,000 ohms to 200,000 ohms depending mainly upon the force exerted on the brush while' brushing. This resistance value is suflicient to cause the dissipation of any static that might be accumulated by the brush.
Having thus described my invention, what I claim and desire to protect by Letters Patent is: 1. A brush which when used in a dry condition will remain static free, comprising a head having bristles secured therein and a handle extending from the head, the handle and head being coated with a conductive material to disperse static charges, and the bristles having a thin electricallyv conducting coating disposed thereupon so as not to bond the contacting bristles together, to thereby provide a conducting path from the bristles to the handle.
2. A brush which when used in a dry condition will remain static free, comprising a head having bristles secured therein and a handle extending from the head, the handle and head having a conductive outer surface adapted to disperse static charges, and the bristles having a thin electrically conducting coating disposed thereupon so as not to bondthe contacting bristles together, to thereby provide a conducting path from the bristles to the handle.
3. A brush which when used in a dry condition will remain static free, comprising a rigid nonmetallic head having non-metallic bristles secured therein, the head having a conductive outer surface adapted to disperse static charges, and the bristles having a thin electrically conducting coating of plastic material disposed thereupon so as not to bond the contracting bristles together, to thereby provide a conductive path from the bristles over the outer surface of the head.
LOUIS MARIC JK.
REFERENCES CITED The following references are of record in the file of this patent:
UNITED STATES PATENTS Number Name Date 2,304,210 Scott et al Dec. 8, 1942 1,725,852 Cressler Aug, 27, 1929 2,302,003 Cadwell et a1 Nov. 17, 1942