US3605162A

US3605162A - Brush filament and construction therefor

Info

Publication number: US3605162A
Application number: US807314A
Authority: US
Inventors: Mace E Long
Original assignee: Industrial Brush Co
Current assignee: Industrial Brush Co; Industrial Brush Corp
Priority date: 1969-03-14
Filing date: 1969-03-14
Publication date: 1971-09-20
Anticipated expiration: 1988-09-20
Also published as: GB1276212A; DE2012026A1; NL7003655A; CA919362A; FR2038957A5

Abstract

A BRUSH FILAMENT OF POLYMERIC MATERIAL OF NOVEL COMPOSITION AND STRUCTURE PARTICULARLY ADAPTED FOR USE ON NONUNIFORM INTERRUPTED SURFACES SUCH AS VEHICLE SURFACES. A BRUSH FILAMENT OF LIGHT WEIGHT, LOW BREAKING STRENGTH, STRUCTURAL RIGIDLY SUFFICIET TO PROVIDE FULL CYLINDRICAL BRUSH CONFIGURATION AT RELATIVELY LOW RATIONAL SPEEDS, RESISTANCE TO WEAR AND FRAYING OR SPLITTING, AND FREEDOM FROM CURL AND MAINTENANCE OF SEPARATE DISCRETE FILAMENT RELATIONSHIP, THE FILAMENT INCLUDING A TUBULAR PORTION WITH SPACED LONGITUDINAL RIBS, THE RIB EDGES DEFINING PLANES TANGENT TO THE CONVEX SURFACES OF THE TUBULAR PORTION LYING BETWEEN SAID RIB EDGES.

Description

p 20, 1971 "M. E. LONG 3,605,162

BRUSH FILMIENT AND cousmucrxon THEREFOR Filed March 14, 1969 IN vE/vraA? M/Jcs E. Iowa 9 W/M,fl ,/Z. {rm-a United States Patent 1 3,605,162 Patented Sept. 20, 1971 3,605,162 BRUSH FILAMENT AND CONSTRUCTION THEREFOR Mace E. Long, Long Beach, Calif., assignor to Industrial Brush Company, Pomona, Calif. Filed Mar. 14, 1969, Ser. No. 807,314 Int. Cl. A4611 1/00; D01d 5/00; D01f 1/00 U.S. Cl. -159 16 Claims ABSTRACT OF THE DISCLOSURE A brush filament of polymeric material of novel composition and structure particularly adapted for use on nonuniform interrupted surfaces such as vehicle surfaces. A brush filament of light weight, low breaking strength, structural rigidity sufiicient to provide full cylindrical brush configuration at relatively low rational speeds, resistance to wear and fraying or splitting, and freedom from curl and maintenance of separate discrete filament relationship, the filament including a tubular portion with spaced longitudinal ribs, the rib edges defining planes tangent to the convex surfaces of the tubular portion lying between said rib edges.

BACKGROUND OF INVENTION Various types of brush filaments have been proposed heretofore for use in brushing surfaces to be cleaned, as for example vehicles such as automobiles, buses, rail cars, and nonuniform often ornamental surfaces. Exemplary reference is made to automobile washing apparatus known as car washes, in which an automobile is moved by a conveyor through a series of stations where various washing and cleaning operations are performed. At one of these stations cylindrical or configured brushes may be mounted for rotation about axes generally parallel to the surface to be washed. Such brushes are rotatable at selected speeds so that free ends of the brush filaments thereon contact and strike the surface under pressure.

Prior proposed brush filaments for use in such car washes have been made of oriented and nonoriented polymeric materials, each of such materials having certain desirable as well as undesirable characteristics for such use. Improvement of recovery characteristics after deformation has been attempted with unoriented polyolefin filaments of cross-sectional shapes such as described in U.S. Pat. 3,121,040. Strength characteristics including stiffness, resiliency, and durability with a minimum mass of material have been sought by oriented filaments as described in U.S. Pat. 2,637,893. Filaments of relatively high stiffness, resiliency and strength provided by an oriented polymeric material have required relatively high rotational speeds of a brush means carrying such filaments because of the relatively heavy weight and size of such filament. Such oriented filaments have also exhibited a tendency to split, to fray and to part along lines of lamination produced by orientation of the material. Such splitting and fraying encourages and produces entanglement of the split portions of a filament and also with adjacent filaments. Entangled and snarled filaments in such a rotating brush results in snagging and catching of door handles, sideview mirrors, license plates and other projections or ornamentation on a vehicle and results in damage. Often a sideview mirror may be pulled from the car.

Prior proposed filaments have also included a crosssectional configuration which appeared to favor entanglement of split filament portions, such as X, Y and various other cross-sectional configurations having a substantial amount of the material of the cross-section extending outwardly from the axis of the filament. Such configurations ice provided relatively deep longitudinal recesses or channels which appeared to contribute to entanglement of the filaments.

Prior proposed filaments used in vehicle washing brushes were generally made of a paraffin base material, such as certain polyethylenes, which upon striking a surface often deposited a waxy-like streak on the surface. Obviously such streaking of glass and metal surfaces on a car were not desirable in a car washing and cleaning operation. Such polyethylene base material had a modulus of fiexure of about .06. 08 10 p.s.i.

The present invention, therefore, contemplates a novel brush filament of chemical and physical characteristics which obviate the disadvantages of prior proposed brush filaments and which provide a low cost readily manufactured brush filament having advantages and characteristics not present in prior proposed filaments.

The present invention contemplates a brush filament structure of tubular form having a relatively thin wall section and having a plurality of spaced parallel longitudinal ribs extending from the external surface of the tubular portion a relatively short distance whereby the tubular portion is provided structural rigidity and an external configuration which does not show a tendency towards entanglement of individual filaments in a brush means. The present brush filament is also made of a polymeric material of a virtually nonwaxy base to avoid streaking and which is only partially oriented so that splitting or fraying of the filament is virtually eliminated.

The primary object of the present invention, therefore, is to provide a novel brush filament.

An object of the invention is to disclose and provide a brush filament having a cross-section which enhances water holding and transfer capacity of the filament and provides sufficient rigidity so that full cylindrical brush configuration will be achieved at relatively low rotational speeds.

An object of the invention is to disclose and provide a brush filament of novel composition which eliminates the deposit of wax-like streaks on surfaces being brushed thereby.

Another object of the invention is to disclose and provide a brush filament wherein the material is only partially oriented to an amount insufficient to produce a laminar construction, thereby virtually eliminating fraying of filament ends and resulting entanglement while the filament structure provides rigidity, stiffness, and recovery from deformation to provide a filament especially useful in vehicle washing.

A further object of the invention is to disclose and provide a brush filament of novel composition and structure wherein the rfilaments do not cling to each other but maintain separate discrete identity and do not become interlocked and entangled during a brushing operation.

A still further object of the invention is to disclose and provide a brush filament having a tensile strength in the order of 3 to 5 lbs. so that said filament will break without damage to automobile ornaments and accessories on the surface of a car.

A still further object of the invention is to disclose and provide a filament composed of a novel composition material which is only partially oriented and which has a low breaking strength and provides a clean, nonstringy fracture.

Other objects and advantages of the present invention will be readily apparent from the following description in which the drawings illustrate an exemplary embodiment of the invention.

'In the drawings:

FIG. 1 is an end view of a filament embodying the construction and composition of this invention.

FIG. 2 is a schematic view of the principal apparatus and method for making the filament shown in FIG. 1.

FIG. 3 is a schematic fragmentary view of a brush means provided with the filament of this invention.

FIG. 1 shows a brush filament generally indicated at 10 embodying the present invention. The exemplary brush filament 10 comprises an elongated tubular portion 111 having a generally cylindrical external surface 12. The wall thickness of tubular portion 11 is relatively thin and a typical wall may be in the order of .004 thick. A typical inner diameter of the tubular portion may be in the order of .036". Filament 10 may be cut to any selected length, as for example from 3 /2 and up. It will be understood that the dimensions indicated above are typical of a specific example and may be varied. It will thus be apparent that an exemplary brush filament 10 is relatively small in material cross-sectional area and dimension in relation to its length. The invention thereby comprises the provision of a novel polymeric material compounded, formulated, processed and extruded into a structural shape so that an effective brush filament is provided with such dimensional relationships.

In diametrically opposite relation a plurality of parallel longitudinal ribs 14 may project from external surface 12, said ribs having a generally triangular cross-sectional configuration with a base at surface 12 and terminating at longitudinal rib edges 15 of transversely rounded configuration. The height of said ribs is related to the curvature of the tubular portion lying between adjacent ribs 14. In the example, a generally cylindrical tubular portion is illustrated, ribs 14 are spaced about 90 apart, and adjacent edges 15 define a plane indicated at T which is approximately tangential to the external curved surface 12 of the curved wall section 16. Generally speaking, it may be noted that the square figure defined by rib edges 15 and planes T connecting said edges has inscribed therewithin outer cylindrical external surface 12 of tubular portion 11. Such relationship between edges 15, the curved wall therebetween and the plane T tangential thereto may be provided with tubular portions inscribed within generally triangular and other polygonal cross-sectional configurations.

The provision of spaced adjacent parallel ribs 14 in association with the tubular portion 11 provides a structurally stable filament which does not tend to bend, twist, or curl about the longitudinal axis of the tubular portion. Moreover, the spaced ribs and curved intervening wall section provides a pair of spaced channels 18 which serve to retain water on the brush filaments during use and to convey said water along said channels 18 to the free ends of the filament for lubricating the pressure contact of the brush filaments against the surface being washed.

Filament 10 is made of a thermoplastic material, such as an alpha-olefin polymer and copolymer. Generally speaking, filament 10 is obtained from a mixture of ethylene-propylene-polyisobutylene, ethylene vinyl acetate, and polyethylene. A specific example of a mixture for filament 10 comprises by weight about 90% ethylenepropylene-polyisobutylene, about to 7% of ethylene vinyl acetate, and about 3% to 5% of a high density linear polyethylene. The ethylene-propylene-polyisobutylene is preferably in the following proportions: ethylene 4%, propylene 87%, and polyisobutylene 9%. The ethylene vinyl acetate is preferably in the following proportions: ethylene 8% and vinyl acetate 92%. The ethylene vinyl acetate reduces the modulus of elasticity to provide a low tensile strength and to limit elongation. Filament is provided with a breaking strength in the order of 3 to 5 lbs. with elongation of not greater than 10% when a 10 long sample is stretched at the rate of 1" per second.

A high density linear polyethylene in the amount of about 3% to 5% by weight provides a carrier for the addition of suitable coloring materials to the mixture so as to produce various colored filaments for making a 4 brush attractive. Black, white, reds and greens and other colors may be used, the color material being Well known and comprising various oxides. The crystalline structure of the high density linear polyethylene facilitates the introduction of color uniformly into the filament material.

A mixture of the ingredients mentioned above are mechanically blended in a suitable well known mixing apparatus. After mixing they may be fed to a thermoplastic extruding device 20* of well known manufacture where the mixture is heated into a homogeneous viscous mass. The material may be heated to about 435 F. for extrusion thereof.

Extruding device 20 includes an extruding head 21 having a die to form the desired tubular and rib configuration illustrated in FIG. 1. Such a die includes an axially disposed mandrel (not shown) having an axial bore for admission of air under low pressure into the mass being extruded through the die to form the hollow tube. Such air may be introduced to the extruding head 21 by a conduit 22 connected to a high volume low pressure air source (not shown), such air being furnished at about .6 psi. at 8 c.f.m. The dimensions of the tubular filament are subject to variation by the pressure air supplied to the extruding head and such a source of air may be furnished with a positive volume displacement adjusting means for controlling such dimensions of the tubular filament.

The extruded filament traverses an air gap 23 of approximately /2" between the exit face of the die and the introduction of the extruded filament into water bath 24.

Water bath 24 has a temperature of approximately F. to F. In the water bath the extruded filament is drawn over a plurality of idle rolls of approximately Vs" diameter, made of suitable plastic material, such as p lyvinyl chloride and arranged along an arcuate curve so as to produce controlled stretching of the filament as it iS guided and pulled across the idle rolls. In the example shown in FIG. 2 groups of idle rolls 25 may be suitably arranged as exemplarily indicated so that the filament may pass through the water bath and exit therefrom at a temperature of approximately 140 F. to 160 F. A pair of pull rolls 27 draw the extruded filament through the bath 24 at a selected rate of speed.

Passing of the filament through the water bath and stretching the filament therein serves to orient the material of the filament. The degree of stretching is carefully controlled by the rotation of pull rolls 27 and in the present invention the stretching of the filament is at a ratio of approximately 5.5 to 1. Full orientation of an extruded filament of the present composition would normally be drawn to an oriented ratio of about 8 /2 to 1- Thus, in the present filament the rearrangement of the molecules with respect to the axis of the filament is on y partially completed with respect to the normal parallel oriented relation. Partial orientation is desired in H16 present example to reduce and eliminate splitting or lamination of the filament which might produce fraying of ends of the filament during use. Thus by only partially orienting the extruded filament a brush filament is provided which resists and eliminates entanglement With other filaments and possible catching on projection or irregularities on a surface being washed.

After the extruded filament is drawn out of water bath 24 it may cut to a preselected length by suitable cutting means schematically indicated at 29. The cut filament lengths may be collected into a group or a bundle schematically indicated at 31 and may then be transported to a hot air oven schematically indicated at 33 where they may be subjected to heat treatment for approximately two hours at an oven temperature of between to 210 F. Such heat treatment of the partially oriented extruded filament serves to relieve stresses in the filaments. After heat treatment the filaments are withdrawn from the oven and are permitted to return to ambient tempera ture and may then be employed in the manufacture of a brush means.

The characteristics of filament 10 as provided by the formulation exemplified above and the process of extrusion, orienting, and heat treating forms a filament having a composition and structure particularly desirable for filaments for vehicle washing brush means and other utility where a filament is required having the characteristics described below.

The filament 10 after being so processed provides a tensile breaking strength of between 3 to 5 lbs. which occurs after not greater elongation of the brush filament than approximately 10%. Thus when a filament engages a surface being washed and is exemplarily drawn into a crevice or in some way becomes caught on the surface, it will be apparent that the bristle will break before damage to the article or vehicle being washed.

Filaments 10 also provide straight filaments which do not twist or curl about their longitudinal axis. Limitations on the tendency to curl are limited to variations from a vertical line of not more than /2" when a filament 10 long is held vertically. The straightness of the filament is caused by the particular arrangement of the molecular structure in the tubular portion and since full orientation or realignment of the molecules into parallel relation with the longitudinal axis has not been completed by reason of only partial orientation, any breaking of a filament results in a clean fracture without attendant stringiness, splitting or fraying in the filament portion adjacent to the fracture.

It should also be noted that the weight of the filament when dry is quite light, the weight of 1,000 filament inches (100 filaments 1 long each) being in the range of approximately 10.8 gms. to 11.3 gms. The filament 10 is also provided with surface characteristics which virtually eliminate the deposit of a waxy type streak on the surface being washed because of the composition described above which provides a virtually wax free base.

Filaments 10 have a density of about .9041 and a modulus of flexure of about between 1.0-1.2)(10 p.s.i. While the flexural modulus of the base copolymer material may have been substantially higher, the presence of the ethylene vinyl acetate in the mixture reduces the flexural modulus. The relatively light weight characteristics of filament together with the structural cross-sectional configuration provides a virtually self supporting brush filament when secured at one end and disposed horizontally for a length of about 10'. Beyond 10" such as when brush filaments of about 16" are employed the overall deflection of a filament of about 16" long is only approximately 8" to 10 at its free end. Such structural rigidity of the brush filament together with their light weight and relative stiffness permits the bristles to stand out from a brush core with relatively little drooping or sagging.

Since the filaments 10 may be used in car washes using hot water, the material of the present invention has been formulated to withstand and resist hot water (up to about 215 F.) without losing its partial orientation and remaining effectively operable.

Filament 10 has also exhibited heat resistance under conditions of pressure referred to here as fiber stress as when a filament is rotated at a selected peripheral tip speed with a selected interference (for example 1") with a surface being washed in the presence of hot water. Deflection-temperature tests conducted under ASTM Test Method D648 indicated fiber stress of 264 p.s.i. at 125-140 F. and of 66 p.s.i. at l85230 F. Filament 10 exhibited continuous resistance to heat without deformation or deflection at temperatures of between 190-240 F.

Filament 10 is inert with respect to fungi and bacteria, has a water absorption characteristic of less than .0l%, and is chemically resistant to organic substances. When used against a surface with contact forces between about 10 to 18 lbs., filament 10 exhibits good abrasion resistance.

Structural features are exemplified in FIG. 3 which schematically shows a brush means generally indicated at 40 formed from filaments 10. Brush means 40 may include a center core means 41 of well known construction and upon which a plurality of parallel brush strips 42 may be mounted. Each brush strip 42 may include a plurality of filaments 10 held in said brush strip in usual manner and containing a desired density of filaments per unit of length of the brush strip. The core means 41 may be carried upon shafts 43 supported in suitable bearings in arms 44 which may be pivotally mounted for movement about a vertical axis 45 to permit the brush means 40 to swing into adjacent relation with a surface to be washed. One of the arms 44 may carry drive means (not shown) for rotating the core means 41 at selected speeds.

In such a brush means 40 provided with filaments 10 of the present invention when the brush means is rotated at relatively low speeds, such as to r.p.m., the filaments 10 (about 22" long) stand straight out along radial lines at such low speeds. Relatively low speeds in this application means rotational speeds of between 50% to of rotational speeds of vehicle washing brush means utilizing prior proposed filaments of substantial length such as 16" to 26". Those skilled in the art readily recognize that a relatively low rotational speed for a vehicle washing brush is advantageous when the filaments are standing out fully as along a radial for providing a lower peripheral speed at the tip of the filaments, and thus a lower striking or impact pressure on the surface being washed. Thus, tendency to streak or to grab antennas, door handles and the like is reduced.

In addition, a brush means 40 provided with filaments 10 operating at a relatively low rotational speed permits the filaments 10 to retain and hold water on the bristle. The particular cross-sectional configuration of filament 10 which provides essentially spaced channels along each face thereof serves to hold water and to permit the water to flow straight down the filament for deposit upon the surface being washed and for lubrication of the passage of the bristle over the surface to remove dirt and other foreign matter attached to the surface.

Another advantage of the provision of brush means 40 with filaments 10 which permit relatively low rotational speeds together with the relatively stiff characteristics imparted to filament 10 because of the cross-sectional configuration is that the pumping action of the filaments (occurring because of wind resistance of the filament during rotation) is reduced and there is less distortion or defor mation of the bristle because of the wind resistance. Thus, the straight noncurling filament 10 provides an effective means for conveying and transferring water to the surface being washed.

The structural configuration of filament 10 reduces the tendency of the filament to kink under bending conditions. The composition of the material together with the structural configuration of the filament affords rapid recovery from bending conditions and even when the filament is subjected to kinking the filament is capable of re covering from such deformed kink condition to an effectively operable condition.

The filaments 10 when used in such a brush means 40 facilitate the discrete separate independency of each filament with respect to an adjacent filament. It should be noted that the height of ribs 14 of filament 10 is so reduced with respect to the curved section of the tubular portion between said ribs that a rib of an adjacent filament is prevented from becoming deeply inserted between said ribs and in engagement therewith so that the two adjacent filaments would tend to interlock or cling together. Thus, the cross-sectional configuration of filament 10 with the tubular portion virtually inscribed within a polygon defined by edges of the outwardly extending ribs provides a filament construction which is structurally stiff and rigid and '7 which prevents clinging of adjacent filaments to each other. Such structural stiffness of filament continues to be exhibited even when in the wet humid conditions prevalent in vehicle washing installations.

It will be understood by those skilled in the art that various modifications and changes may be made in the filament and composition therefor described above which come Within the spirit of this invention and all such changes and modifications coming within the scope of the appended claims are embraced thereby.

I claim:

1. A brush filament of polymeric material comprising:

an elongated tubular portion having an external surface and having a longitudinal axis;

a plurality of longitudinal ribs in parallel relation to said axis and extending from said external surface of said tubular portion;

adjacent ribs having longitudinal rib edges defining a plane which is approximately tangent to a portion of the external surface of the tubular portion lying between said adjacent ribs;

whereby an end of said filament engageable with a surface being brushed is adapted to contact said surface at said rib edges and tangential surface portion while providing a longitudinally extending channel for conveying fiuid to said surface during such contact.

2. A brush filament as stated in claim 1 wherein said filament has a breaking strength in the order of 3 to 6 lbs.

3. A brush filament as stated in claim 1 wherein said ribs are of generally triangular cross-section and have rounded longitudinal rib edges.

4. A brush filament as stated in claim 1 wherein said polymeric material is only partially oriented.

5. A brush filament as stated in claim 4 wherein said polymeric material includes by weight: ethylenepropylene-polyisobutylene in the order of about 90%, ethylene vinyl acetate in the order of from 5% to 7%, and high density polyethylene in the order of 3% to 5%.

6. In a brush construction for washing surfaces in the presence of a fluid, such as Water and adapted to provide full brush configuration at relatively low rotational speeds, comprising:

a core means; brush strip means on said core means; said brush strip means including light weight brush tubular filaments projecting from said core means and having a cross-sectional configuration comprising curved wall sections having external surfaces,

spaced parallel ribs at ends of said curved wall sections and having rib edges lying in a plane approximately tangent to said external surface;

whereby said tubular filaments with said ribs maintain discrete separate relation and provide therebetween fluid conducting channels for conveying fluid to free ends of said filaments for washing and lubricating a surface being cleaned without entanglement or interlocking of adjacent filaments.

7. A brush construction as stated in claim 6 wherein said brush filaments comprise a partially oriented polymeric material, said partial orientation being insuflicient to produce a laminar arrangement with resultant splitting of said filaments.

8. A brush construction as stated in claim 7 wherein said brush filaments have a breaking strength in the order of 3 to 6 lbs.

9. A brush construction as stated in claim 6 wherein said filaments are virtually curl-free.

10. A light weight, low breaking strength, brush filament of polymeric composition effectively operable in a hot humid environment under conditions of deflection, deformation and kinking of the filament, comprising in combination:

a hollow tubular member having a plurality of longi tudinal parallel external ribs;

said tubular member being formed of an extruded polymeric material comprising by weight: about ethylene-propylene-polyisobutylene, 5% to 7% of ethylene vinyl acetate, and 3% to 5% of high density polyethylene;

said member being partially oriented in the ratio of about between 5 and 6 to 1.

11. A brush filament as stated in claim 10 wherein said ethylene-propylene-polyisobutylene is in the following proportions: ethylene about 4%, propylene about 87%, and polyisobutylene about 9%.

12. A brush filament as stated in claim 10 wherein the ethylene vinyl acetate is in the proportions of about 8% ethylene and 92% vinyl acetate.

13. A brush filament as stated in claim 10 wherein the fiber stress of the tubular member is in the range of about 264 p.s.i. at -140 F.

14. A brush filament as stated in claim 10 wherein the fiber stress of the tubular member is in the range of about 66 psi. at -230 F.

15. A brush filament as stated in claim 10 wherein the tubular member has a modulus of flexure of between about l.01.2 1O p.s.i.

16. A brush means comprising:

a core means;

and a plurality of brush filaments carried by said core means; said brush filaments comprising a tubular member having a plurality of longitudinal parallel external ribs;

said tubular member comprising a polymeric material partially oriented in a ratio of about between 5 and 6 to 1; and

including a composition of ethylene-propylene-polyisobutylene, ethylene vinyl acetate, and polyethylene having a modulus of flexure of between l.01.2 10

psi.

References Cited UNITED STATES PATENTS 3,059,991 10/1962 Munt l5l59(A) 3,238,553 3/1966 Bailey et al l5l59 3,344,457 10/1967 Grobert l5l59 3,256,545 6/1966 Lewis, Jr. et al l5l59 3.402,4l6 9/1968 Shaw et al. l5l59 3,411,979 11/1968 Lewis, Jr. l5159(A) FOREIGN PATENTS 531,551 10/1956 Canada l5l59 1,303,179 7/1962 France 264-177(1 1,140,901 12/1962 Germany 15159(A) 838,141 6/1960 Great Britain 15--159(A) PETER EELDMAN, Primary Examiner US. Cl. X.R.