US2674759A

US2674759A - Brush construction

Info

Publication number: US2674759A
Application number: US48631A
Authority: US
Inventors: Archie N Solberg
Original assignee: GLENWOOD S MACK
Current assignee: GLENWOOD S MACK
Priority date: 1948-09-10
Filing date: 1948-09-10
Publication date: 1954-04-13
Anticipated expiration: 1971-04-13

Description

April 13, 1954 A. N. SOLBERG 2,674,759

BRUSH CONSTRUCTION Filed Sept. 10, 1948 2 Sheets-Sheet l i 7 YJ 8 5 6 INVENTOR. 6120105 M 5OL8ER6 Patented Apr. 13, 1954 UNITED STATES ATENT OFFICE BRUSH CONSTRUCTION Application September 10, 1948, Serial No. 48,631

6 Claims. '3

The invention relates to a brush of improved construction.

A continual problem in the brush making art is the difiiculty of obtaining practical as-Well as attractive means for mounting the. bunches or tufts of bristles on a brush handle. Mechanical devices for binding or clamping the bristle tufts to the handle are ordinarily unsatisfactory because of the inevitable loosening of the clamp, whereupon the individual bristles fall or are pulled out of the tuft. The use of a cementitious agentto form a hardened body or matrix in which a tuft may be permanently cemented has been found to be the most satisfactory means for mounting the tuft on the brush handle.

The problem of the selectionof the most satisfactory cement has been given considerable at" tention in the art, but for many years animal glue has enjoyed practically uncontested prevalence as the cement for mounting the. tuft on the handles of the brushes. While animal glue has its shortcomings, it appeared that no other material could be used satisfactorily asa substitute. Practically all synthetic resins are more expensive than animal glue, and resins available in attractive, light colors are particularly expensive. Other resins are brittle or flexible and must, therefore, be supported or reinforced, e. g., by a metal ferrule. Still others are not sufiiciently resistant to water or to the organic solvents used in paints.

Animal glue isan impure form of gelatin, being a typical organic nitrogenous colloidal substance of the protein class. It absorbs cold water with much swelling and dissolves in hot water. It is a thermoplastic substance. It exhibits great strength when used in the form of a thin adhesive film, but it is quite weak and brittle when used in the form of a solid body or a layer of substantial thickness. Ordinarily, when used in fabrication of brushes, animal glue must be supportedand coveredas'much' as possible. The prevalent use of animal glue as a cement for brush bristles can be attributed mainly to the fact that none of the workers in the artehave been able to find a material which is appreciably better than the glue.

Any synthetic resin which is to be used in preference to animal glue in the fabrication of brushes must have substantially better properties to compensate for the higher cost of the resin. As a rule, any synthetic resin which would be acceptable would have to be an infusible resin, ,since an i-nfusible resin doesnot soften when warm and is not soluble in water andJmost organic solvents. However, infusible resins in general can be formed only by the simultaneous application of heat and pressure. Thus, in the manufacture of a brush having the tuft. cemented in an infusible resinous body, it is generally necessary to employ hot pressing equipment, which is very cumbersome and expensive, as well as impractical in the brush making art.

Urea-formaldehyde resin is one of the most useful infusible resins, because it is colorless, resistant to light, resistant to water and organic solvents, and relatively inexpensive. Moreover, urea-formaldehyde resin is unique among infusible resins in that it can be produced without the application of heat, by gelling and hardening a solution of urea-formaldehyde condensation product by means of a hardening catalyst. After a solid body has been formed by hardening a solution of a urea-formaldehyde condensation product, however, the body cracks and disintegrates in drying out. It is believed that the disintegration of a body formed by hardening such a solution is due to the colloidal nature of the solution. Evaporation of the solvent from the solution leaves a solid that is peculiarly lacking in structural strength and continuity.

The principal object of the invention is the fabrication, by inexpensive methods, of a brush of superior durability having the tuft mounted in a binder comprising an infusible synthetic resin. More specific objects and advantages are apparent from the description, in which reference is had to the accompanying drawings illustrating brushes fabricated in accordance with the invention.

Figure I of the drawings is a plan View of a brush embodying the invention.

Figure II is a side elevaticnal view of the brush shown in Figure I.

Figure III is a plan view of an artists style brush embodying the invention.

Figure IV is a side elevational View of another brush embodying the invention.

Figure V is an enlarged vertical sectional view taken substantially along the line V--V of Figure II.

Figure VI is an enlarged fragmentary plan view of the ferruled portion or the brush shown in Figure III, with part broken away and part shown in section.

Figure VII is a plan view of a paint brush embodying the invention with part brokenaway and part shown in section,

Figure VIII is a plan view of a quill brush embodying the invention.

Figure IX is a plan view of another brush embodying the invention.

Figure X is a plan view of still another brush embodying the invention.

Figure XI is an enlarged vertical sectional view taken substantially along the line XI-XI of Figure X.

These specific drawings and the specific disclosure that follows merely disclose and illustrate the invention and are not intended to limit its scope.

Referring to the drawings in detail, in Figures I and II, the handle I of the brush illustrated consists of a manually grippable portion 2 at one end and a wedge-shaped portion 3 at the other end. A generally hemi-cylindrically-shaped solid cement body 4 (see Figure V) is mounted on and adheres to each face of the wedge-shaped portion 3. Embedded in each cement body 4 is the butt 5 of a bristle tuft 6 which extends from one end of the cement body 4 outwardly to form a sword-like brush tip 1. Covering what would otherwise be the exposed portion of each cement body l is a layer of binder 8 integrated with the cement body 4 so as to be a peripheral portion thereof and to impregnate a peripheral portion of the butt 5 of the tuft 6.

The solid cement body 4 may consist of any substance which can be used to receive the butt 5 of the tuft 6 and penetrate therein so as to contact and adhere to the basal portion of each bristle in the tuft B when such substance has set to form a solid. Since one of the principal advantages of the invention it is adaptability to inexpensive materials, it is not anticipated that the substance will be an expensive ingredient and the preferred substance is animal glue.

The bristle tuft ii is composed of camel hair.

Camel hair is the name given to hair obtained from a Siberian squirrel. The hairs are removed from the tail of the squirrel and heated to remove the kinks and to render the hairs resilient. The hairs so obtained taper to very fine ends and are particularly useful in paint brushes because they permit the drawing of extremely fine lines. Camel hair is preferred in the practice of the invention also because it has excellent absorption properties, and the brushes illustrated in the drawings contain camel hair bristles. However, any of the usual types of bristles may be used in the practice of the invention, including bristles from animals such as hogs and horses and synthetic bristles such as those made from nylon and cellulose acetate. When particularly smooth bristles such as those made from nylon are used, the basal portions of such bristles preferably are sanded before being treated with the cementitious agent. Bristles from animals, i. e., animal hairs, are preferred for use in the practice of the invention since they are usually very absorbent and thus may be readily impregnated with the binder 8.

The first step in the fabrication of the brush illustrated in Figures I, II and V involves the cementing of the tuft 6 on the handle I using a substance such as animal glue. This step may be carried out simply, for example, by dipping the butt 5 of the tuft 6 in molten glue and then placing the butt 5 on the face of the wedgeshaped portion 3 of the handle I and permitting the glue to set. The glue sets to form the generally hemi-cylindrically-shaped solid cement body 4. The next step involves the application of the binder 8 of the invention so that it impregnates a peripheral portion of the butt 5 of the tuft 6. The binder may be applied in one or more coats.

The binder 8 comprises a hardened urea-formaldehyde condensation product. In accordance with the invention, the binder is applied by inoistening the peripheral portion of the cement body 4 with a solution of a urea-formaldehyde condensation product and a hardener therefor. The solution penetrates the cement body t and impregnates a peripheral portion of the butt 5 of the tuft 6. The urea-formaldehyde condensation product then hardens to form a layer which includes the peripheral portion of the butt 5 of the tuft 6, as well as the peripheral portion of the cement body 4 which has been permeated with the solution of the urea-formaldehyde con-- densation product. It has been discovered that the layer of the binder 8 so formed does not crack and disintegrate like the bodies heretofore prepared by gelling and hardening a solution of a urea-formaldehyde condensation product. In fact, contrary to expectations, the layer of the hardened binder 8 gives great strength to the cement body so that the cement does not crack or crumble during use, as it would if the cement body of, for example, animal glue were left uncovered and unsupported. The binder 8 is bifunctional in that it forms a protective waterresistant covering for the cement body 4 and also supports and strengthens the cement body 4. It is believed that the failure of the layer of hardened urea-formaldehyde condensation product to disintegrate results from the fact that the layer dries out appreciably during hardening of the reaction product.

The binder 8 may contain various modifying agents such as plasticizers, lubricants, opacifiers and pigments, as well as resins such as unsaturated polyesters (i. e., polybasic alcohol-polycarboxylic acid polyesters) rosin-modified alkyds, ethyl cellulose and other synthetic resins. The foregoing ingredients may be used in solution with the urea-formaldehyde condensation product, or separately. As used herein the term binder means the infusible urea-formaldehyde condensation product and any of the foregoing modifying agents or resins which may have been added therewith. It has been found that the best results, particularly in strength, cannot be obtained if the binder does not consist of at least 50 per cent by weight of infusible ureaformaldehyde condensation product. The preferred proportion in the binder is at least about per cent by weight of infusible urea-formaldehyde condensation product, and the optimum results are obtained using a binder consisting essentially of infusible urea-formaldehyde condensation product. Of course, a certain amount of other ingredients such as the hardener or its decomposition products ordinarily are present in the infusible binder.

Although the solution with which the cement body 4 is moistened may be a solution of a ureaformaldehyde condensation product in any desired solvent such as an alcohol or an alcohol diluted by a hydrocarbon, the most economical solvent is water. The hardening catalyst may be dissolved in the solution before the cement body 4 is moistened therewith, or it may be applied in any other desired manner to cause it to dissolve after the cement body 4 has been moistened with the solution.

The hardeners that are useful with urea-formaldehyde condensationproducts are acid substances such as acid salts and various substances that liberate acids. Organic or inorganic acids may be used, but acid salts such as ammonium chloride are preferred.

The quantity of hardening agent employed depends upon-the speed of hardening desired,-

and the speed of hardening should be so coordinated with the speed of drying that appreciable drying occurs during the hardening. Thus, when a sufficient proportion of hardener is used to cause hardening to take place in one hour, the binder 8 must be applied in a thinner layer than when the hardening requires, for example, 8 hours. The speed of drying, and'consequently the permissible thickness of the layer, will vary with the relative humidity of the atmosphere and the porosity or the absorbent char acteristics of the cement body and the bristles therein. The ratio of the binder 8 to the cement body 4 that can be employed will vary with the coarseness of the bristles and the texture of the cement body.

In the preparation of an aqueous solution of a urea-formaldehyde condensation product for use in carrying out the invention, it is preferable to carry the urea-formaldehyde condensationas far as it can be carriedwithout precipitation. A suitable solution of a urea-formaldehyde condensation product may be prepared as follows:

Urea and formaldehyde in a molar ratio of 1:2 are gently refluxed in an aqueous solution that has been brought to a pH of 4.5-5.0 by means of sodium hydroxide. After the refluxing has been continued long enough (about one hour) to carry the urea-formaldehyde condensation to the desired stage, the solution is neutralized and evaporated under a vacuum to the desired concentration.

To facilitate storage or shipment, the ureaformaldehyde condensation product may be obtained in granules or powdered form by drum drying or spray drying the solution so prepared. If desired, the dry powder may be applied to the peripheral portion of the cement body 4, and then moistened. However, it is preferable to redissolve the urea-formaldehyde condensation product so that a peripheral portion of the butt 5 of the tuft 6 may be better impregnated with the resulting solution. A solution used for moistening the cement body 4 should be no more dilute than necessary for convenient application to the surface of the cement body 4 because a more dilute solution makes the material harder to dry.

The amount of the binder t which may be used in the practice of the invention is simply the amount necessary to give the desired strength and support to the cement body 4 so that the cement body 4 does not crack or crumble during ordinary use of the brush. One of the aspects of the invention resides in the discovery that it is possible to obtain such a layer of infusible urea-formaldehyde condensation product which does not crack or disintegrate. The amount of the binder 8 actually used varies with the size and shape of the cement body t, but this amount can be determined readily by the worker in the art to suit his particular case. Ordinarily, an amount of hardened binder 8 that is as little as 3-5 per cent of the weight of the cement used may be used to obtain appreciable impregnation of a peripheral portion of the butt 5 of the tuft 6, i. e., to obtain appreciable improvement in strength and support for the ce ment body.

In actual practice, care must be taken in applying the solution of the urea-formaldehyde condensation product in order to avoid moistening any part of the tuft 6 other than the butt 5. The portion of a tuft which is impregnated with an infusible urea-formaldehyde condensation product is very rigid, and therefore, should be confined to the butt 5. It is believed that in many cases, for example in brushes using camel hair bristles, a substantial proportion of the unaccounted for strength and support comes from the reenforcing effect of the impregnated bristles in the peripheral portion of the butt 5 of the tuft 6.

Another embodiment of the invention involves the use of a fabric material wrapped around the cement body 4 and impregnated with the infusible binder. In such an embodiment of the invention added strength and support is obtained from the stiffened impregnated'fabric material as well as the impregnated bristles in the peripheral portion of the butt 5 of the tuft 6. Also, the fabric material aids in drying out the urea-formaldehyde condensation product during hardening. An example of this embodiment of the invention is shown in Figure IX, which illustrates a brush which is substantially the same as that shown in Figures I, II and V except that the cement bodies are wrapped with a serving 9, which consists of a cotton thread or yarn. The handle it of the brush illustrated consists of a manually grippable portion H at one end and a wedge-shaped portion 12 at the other end. A generally hemicylindrically-shaped solid cement body (covered by the serving 9) is mounted on and adheres to each face of the wedge-shaped portion l2. Embedded in each cement body is the butt [3 of a bristle tuft M, which extends from one end of the cement body outwardly to form a dagger-like brush tip I5. The serving 5 is wound around the peripheral portion of the cement body and is impregnated with the infusible binder It which is integrated with the cement body and which impregnates a peripheral portion of the butt i3 of the tuft I4.

It is apparent that other fabric materials, particularly cellulosic materials, may be served or wrapped around the cement body in a similar manner, and soaked with a solution of the ureaformaldehyde condensation product before or after wrapping. In this embodiment of the invention it may be possible to obtain the desired strength and support by the use of a very small amount of the infusible binder [6 because of the added strength furnished by the serving 9 impregnated with the infusible binder.

One of the most important aspects of the invention resides in the fact that a brush embodying the invention may be fabricated using an infusible urea-formaldehyde condensation product as the only cementitious agent. Thus, the amount of infusible binder used in the practice of the invention may range from an amount sufiicient to impregnate a peripheral portion of the butt of the tuft (as described in detail hereinbefore) to the entire amount of cementitious agent used (as described in detail hereinafter). The brushes illustrated in Figures III, IV, VII, VIII and X are examples of brushes in which all of the cementitious agent used consists of the infusible binder hereinbefore described.

In Figure IV, thehandle H of the brush illustrated consists of ama-nually grippable-portion 18 at one end and a wedge-shaped portion H9 at the other end. A generally hemi-cylindrically-shaped solid resinous body 20 is mounted on and adheres to a face of the wedge-shaped portion l9. Embedded in the resinous body 20 is the butt 2! of the bristle tuft 22 which extends throughout the resinous body 20 and from one end thereof outwardly to form a brush tip 23. The brush illustrated in Figure IV having only one bristle tuft is a special type of brush used for drawing extremely fine lines, and although this brush serves to illustrate that the invention embodies brushes containing only one bristle tuft, it is to be understood that for the purposes of this invention the number of bristle tufts mounted on the brush is not significant other than that any number may be so mounted.

The bristle tuft 22 consists of the camel hair hereinbefore described. The solid resinous body 20 consists of the infusible binder hereinbefore described. The solid resinous body 23 may also consist of a mixture of the infusible binder and a cement such as animal glue in the proportions hereinbefore described.

In accordance with the invention the binder is applied to the brush illustrated in Figure IV by substantially the same procedure that has been described for applying the binder to the peripheral portion of the cement body 4 of the brush illustrated in Figures I, II and V except that the solution of urea-formaldehyde condensation product is used to moisten directly the butt 2| of the tuft 22 and to penetrate therein so as to impregnate the basal portion of each bristle in the tuft 22 (instead of impregnating only the peripheral portion of the butt 21 of the tuft 22). Thus, the butt 2! of the tuft 22 may be dipped in the solution or the solution may be used to moisten the butt 2| of the tuft 22 which is placed on the face of the wedge-shaped portion 19 of the handle H.

The brush illustrated in Figure IV is particularly characteristic of the discovery upon which the instant invention is based. If the solid resinous body 23 shown in the brush illustrated in Figure IV (i. e., consisting of an infusible ureaformaldehyde condensation product) did not have the bristles embedded therein, the body 2!! would crack and disintegrate in drying out. If the solid resinous body 20 in the brush illustrated in Figure IV consisted of, for example, animal glue instead of the infusible urea-formaldehyde condensation product, the animal glue would crack and crumble readily during ordinary use of the brush. But the body of infusible ureaformaldehyde condensation product having bristles embedded therein as shown in Figure IV is extremely durable and water resistant and does not crack or disintegrate as would be expected.

Although the infusible binder may be used in the practice of the invention alone and without additional support or reenforcement (as shown in Figure IV), in many cases it may be desirable to reenforce the resinous body of infusible binder. Moreover, the solution of urea-formaldehyde condensation product is particularly advantageous for use in the fabrication of brushes when the brush is so designed that it has a ferrule-like end in which the bristles are mounted, since the solution may be poured and gelled easily and at normal temperatures. The brushes illustrated in Figures III, VII, VIII, and X serve to demonstrate the adaptability of the invention to the various types of brushes which are now fabricated in the brush making art.

In Figure III, the handle 24 of the brush illustrated has mounted on one of its ends a seam less metal ferrule 25. One end of the ferrule 25 is crimped onto the handle 24 and the other end of the ferrule 25 embraces a bristle tuft 26 which extends from the ferrule 25 outwardly to form the brush tip 21. The butt 28 of the tuft 26 (see Figure VI) extends into the ferrule 25 and is embedded in a body of infusible binder 29 in the recess formed by the walls of the ferrule 25 and the end of the handle 24. The binder 29 comprises an infusible urea-formaldehyde condensation product as described hereinbefore.

In accordance with the invention, the brush illustrated in Figure III may be readily fabricated simply by clamping the ferrule 25 around the butt 28 of the tuft 26, pouring a small amount of a solution of a urea-formaldehyde condensation product into the open end of the ferrule 25 so as to impregnate entirely the basal portion of the bristles in the tuft 26 and then crimping the ferrule 25 (at its open end) to the end of the brush handle 24. The urea-formaldehyde condensation product hardens to form the body of infusible binder 29 which is extremely water resistant and durable.

In Figure VII, the handle 30 of the brush illustrated has a manually grippable portion 3! at one end and has mounted at the other end a metal ferrule 32. The ferrule 32 is fastened to the handle 20 by means of small rivets 33 piercing one end of the ferrule and the ferrule embraces a body of infusible binder 34 which is set in the recess formed by the walls of the ferrule 32 and the end of the handle 30. Embedded in the infusible binder 34 is the butt 33 of the bristle tuft 36 which extends from the ferrule 32 and the infusible binder 34 embraced therein outwardly to form the brush tip 31. The binder 34 comprises an infusible urea-formaldehyde condensation product as described hereinbefore.

In accordance with the invention, the brush illustrated in Figure VII may be fabricated by first moistening the butt 33 of the tuft 36 with a solution of a urea-formaldehyde condensation product, inserting the butt 33 of the tuft 36 in the ferrule 32 and riveting the ferrule 32 to the handle 30. The urea-formaldehyde condensation product then hardens to form the infusible binder 34 which is extremely resistant to the action of solvents.

In Figure VIII, the brush illustrated has a hollow quill handle 38. A wire loop 39 wrapped around one end of the quill handle 38 serves to crimp the quill around the body of infusible binder 40. Embedded in the infusible binder 40 is the butt 4! of a bristle tuft 42 which extends from the end of the quill handle 38 and the body 'of the infusible binder 40 embraced therein outwardly to form the brush tip 43. The infusible binder iil comprises an infusible urea-formaldehyde condensation product as described hereinbefore.

In acoordance with the invention, the brush illustrated in Figure VIII may be fabricated simply by crimping one end of a quill 38 around the butt 4! of a bristle tuft :12 (by tightening the wire loop 33 around the end portion of the quill-38) and then pouring a small amount of a solution of a ureaformaldehyde condensation product into the open end of the quill 38 so as to flow down the inside of the quill 38 and to impregnate thoroughly the basal portion of the bristles in the tuft 42. The urea-formaldehyde condensation product hardens to form the infusible binder 40 which thoroughly 9 impregnates and holds the butt 4| of the tuft 42 in the quill 38.

In Figure X, the handle 44 of the brush illustrated has a manually grippable portion 45 at one end and a socket 49 at the other end. The socket contains a body of infusible resinous binder 41 (see Figure XI) which adheres to the walls of the socket 46 and has embedded therein the butt 48 of a bristle tuft 49 which extends from the binder 4'! outwardly to form the brush ti 50. The binder 41 comprises an infusible urea-formaldehyde condensation product as described hereinbefore.

In accordance with the invention, the brush illustrated in Figure X may be fabricated by thoroughly moistening the butt 48 of the tuft 49 in a solution of a urea-formaldehyde condensation product and then placing the butt 48 in the socket 46 of the handle 44, or by pouring a small amount of a solution of urea-formaldehyde condensation product into the empty socket 46 in the handle 44 and then stufiing the butt 48 of the tuft 49 in the socket. The urea-formaldehyde condensation product hardens to form the infusible binder 47 which is extremely water resistant and durable.

The use of a brush handle having a ferrule-like end may be preferred in many cases in the practice of the invention, and as hereinbefore shown, the ferrule-like end may assume numerous forms. For example, the brushes shown in Figures III and VII have ordinary metal ferrules mounted on one end of the brush handle. The brush shown in Figure VIII has a hollow handle so that the ferrule-like end is an integral portion of the handle.

The brush shown in Figure X has a socket in the ferrule-like end of its handle and thus the ferrulelike end is also an integral portion of the handle.

Various modifications of the structure may be made without departing from the spirit and scope of the invention.

Having described the invention, I claim:

1. A brush comprising a handle and a tuft having its butt secured to said handle, the butt of said tuft being impregnated with animal glue and having only a peripheral layer impregnated with a hardened binder comprising at least 50 per cent by weight of a hardened urea-formaldehyde condensation product.

2. A brush as claimed in claim 1 wherein the butt of the tuft comprises a peripheral layer of a wrapping of a fabric material impregnated with the hardened binder.

3. A brush as claimed in claim 2 wherein the Wrapping is in the form of a serving.

4. A brush as claimed in claim 1 wherein the tuft is camel hair.

5. A method of fabricating a brush comprising a handle and a tuft having its butt impregnated with animal glue and secured to said handle, characterized by the steps of impregnating only a peripheral layer of the butt of said tuft with a solution of a binder comprising at least by weight of a urea-formaldehyde condensation product and then causing said condensation product to harden.

6. A method as claimed in claim 5 wherein the butt of the tuft is secured to the handle by the addition of a peripheral serving layer and such serving layer is then impregnated with the solution.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 686,655 Higgins Nov. 12, 1901 1,556,298 Morck Oct. 6, 1925 2,015,806 Menger Oct. 1, 1935 2,055,322 Teller Sept. 22, 1936 2,064,949 Rolker Dec. 22, 1936 2,133,335 Wilson et al Oct. 18, 1938 2,194,122 Krams Mar. 19, 1940 2,202,292 Howard May 28, 1940 2,203,501 Menger June 4, 1940 2,310,186 Abrams Feb. 2, 1943 2,311,818 Dawson Feb. 23, 1943 2,332,802 Leonardson Oct. 26, 1943 2,405,658 Kremer Aug. 13, 1946 2,417,750 Hall Mar. 18, 1947 FOREIGN PATENTS Number Country Date 408,072 Great Britain Apr. 5, 1934 506,358 Great Britain May 26, 1939