US2962746A

US2962746A - Paint applicator

Info

Publication number: US2962746A
Application number: US770435A
Authority: US
Inventors: Jr James H Heroy; George E Hartwell; Harry L Sanders
Original assignee: Pittsburgh Plate Glass Co
Current assignee: PPG Industries Inc
Priority date: 1958-10-29
Filing date: 1958-10-29
Publication date: 1960-12-06
Anticipated expiration: 1977-12-06

Description

Dec. 6, 1960 J. H. HEROY, JR, ET'AL 2,962,746 I PAINT APPLICATOR Filed Oct. 29, 1958 2 Sheets-Sheet 1 F'IGJ FIQZ FIQB 3: IP30 42. a E I; .437 ///46 Zl 3 5 Dec. 6, 1960 Filed 001:. 29, 1958 FIG. 7

J. H. HEROY, JR., ETAL PAINT APPLICATOR 2 Sheets-Sheet 2 FIGJO INVENTOR. JAMES A! mseay J4 04-000: A. #Aerwflz n y May A. {MA/052$ PAINT APPLICATOR Filed Oct. 29, 1958, Ser. No. 770,435

4 Claims. (Cl. 15-244) This invention relates to applicators for spreading fluid materials, such as paints, varnishes, lacquers, enamels, suspensions, and the like, upon solid surfaces toprovide protective and/or decorative films upon the latter.

Conventional bristle type paint brushes employed in the application of paints and other coating materials to solid surfaces are characterized by a number of serious disadvantages. For example, they are quite expensive, both from the standpoint of materials employed and of: labor involved in their construction. Likewise, cleaning them after use is a slow and irksome chore. Therefore, the temptation is to shirk the same, with the result that many brushes after one or. two uses are allowed to dry out without cleaning and are thus mined and have to be discarded. Replacement of such units is a serious expense.

Bristle brushes are also characterized by serious operational disadvantages. For example, inthe larger sizes, they are quite heavy and use thereof for several hours, especially in overhead work, is quite fatiguing.

It is very difiicult to lay down a smooth film which is free from brush marks produced by the bristles. Tips of tufts of bristles also tend to flick or snap loose from the main body of bristles during a brushing operation, thus producing spattering and other objectionable effects. Moreover, the conventional brush has but small capacity for holding paints and frequent dippings are required to keep them charged.

In order to obviate the foregoing objectionable features of paint brushes, it has been disclosedto apply coating materials to surfaces by means of rollers having coatings of various materials, such as sponge rubber, fabric and the like. Applicators of this type are usually less expensive than the brushes and often surfaces can be coated with increased speed by their use. However, they are still characterized by a number of serious drawbacks. For example, they are heavy and are diflicult to operate in close quarters, such as in corners. If they are rotated too fast, they will spatter by centrifugal action. Furthermore, the films laid down by them are characterized by so-called orange peel and stippling effects. They cannot be'charged by dipping in a paint can, but require the paint to be poured into a separate pan before application.

It has still further been suggested to form paint applicators by securing upon the end of a wooden handle terminating in a paddle-like or spatula-like blade, a pad formed by folding a sheet of foamed material, such as foamed rubber or a foamed resin about the blade. These applicators are inexpensive to produce both with respect to raw materials employed and labor of fabrication. However, they too are characterized by important shortcomings. For example, they lack in flexibility and springiness when pressed against a surface to be coated and often tend to scrape away the material being laid down as contrasted with spreading it in a thin, uniform layer. In the applicators of the cellular sponge type as heretofore produced, the edge of the paddle or spatula blade also tends quickly to cut through the soft sponge 2,952,746 Patented Dec. 6, 1960 layer at the .line of fold, thus terminating the usefulness of the article.

This inventioncotnprises the provision of an applicator for paints, varnishes, lacquers, enamels and the like, which is quite inexpensive, both from the standpoint of raw materials employed in its fabrication, and also from the standpoint of labor. Furthermore, the applicators fabricated in accordance with the provisions of the present invention are very light of weight and highly efficient in operation being substantially free from most of the difiiculties enumerated in connection with the conventional brushes, sponge type applicators, roller coaters, and the like.

Fundamentally, the applicators embodied in this invention comprise the provision upon a suitable handle, of a brushing head or body of laminated or composite construction in which the inner portion is of light, foam material'which is fairly flexible, but still is characterized by a considerable resilience and springiness. Preferably, the body is also of approximately trapezoidalsection designing it to flex gradually along its length in a relatively uniform curve approximating that of a brush body of pig bristles. and being free from sharp angles and bends. This inner core is then covered by a layer of substantial thickness of a soft, flexible material designed to hold and to spread the coating material to be applied.

For a better understanding of the invention, reference may now be had to the accompanying drawings in which Fig. l is a side view partly in elevation and partly in section of an applicator constructed in accordance with the provisions of the invention.

Fig. 2 is; an edge view also partly in elevation and partly in section of the construction as shown in Fig. 1.

Fig. 3 is a side view partly in elevation and partly in section of a modified form of the applicator.

Fig. 4 is a side view with the handle broken away of the construction shown in Fig. 3.

Fig. 5 is a side view of a further modification of the applicator.

Fig. 6 is a section upon the line VI-Vl[ in Fig. 5.

Fig. 7 is a view partly in elevation and partly in section showing a stage in one appropriate method of forming the covering element of the applicator illustrated in Figs. 5 and 6.

Fig. 8 is a view partly in elevation and partly in section showing the stage of forming a core in the covering shown in Fig. 7.

Fig. 9 illustrates a stage in a method of forming a cup-like covering of soft, flexible, foamed material.

Fig. 10 is a view partly in elevation and partly in section of the body formed by the application of the method illustrated in Fig. 9.

Fig. 11 is a view partly in elevation and partly in section illustrating a further method for forming a cellular core that can be used in the applicator of this invention.

Fig. 12 is a view also partly in elevation and partly in section illustrating the use of the core shown in Fig. 11.

Fig. 13 is a View partly in elevation and partly in section illustrating molding a covering upon a preformed core to provide an applicator body.

Fig. 14 is a fragmentary isometric view showing the cutting of cores from a bar or billet of plastic, foamed material.

Fig. 15 is a view illustrating the use of a paint applicator embodying the principles of the invention.

A paint applicator constructed in accordance with the provisions of the present invention as illustrated in Figs. 1 and 2, comprises a plattened body portion 20, comprising a cellular core portion 21 and a highly flexible, soft cover 22 disposed thereabout. The core is preferably approximately trapezoidal in section and comprises a relatively thick base portion and tapers down to a substantially thinner tip portion as at 23. The taper is so selected as to obtain a relatively uniform bending or flexure of the applicator body during the working stroke in a painting or coating operation. This curvature need only be approximate so long as the body does not bend sharply at any one point. A curvature substantially corresponding to that shown in Fig. 15 is very satisfactory. The thickness at the base may be about 1.5 to 6 times that at the tip.

Both the core portion 21 and the cover 22 preferably are of a flexible material and it is desirable that the core be of foamed material, such as foamed polyurethane resin, foamed rubber, foamed vinyl resin or various other embodiments of foamed material having a suitable degree of cellularity and proper rigidity. For best results it is considered that the core should be of aPandux value in a range of about 40 to 90. Its density in pounds per cubic foot may be in a range of about 1 to 8.

The covering 22 should be of quite soft flexible porous material and at least at the present time, it is regarded that the softer grades of foamed polyurethane resin are especially suitable for the purposes. However, other soft flexible materials adapted to hold and transfer paint may also be employed. Examples of such materials comprise fabrics of so-called Dynel, which is conventionally employed as a coating or cover for paint applicators of the roller type. It will also be apparent that other light flexible material including wool, cellulose sponge, even natural sponges, sponge rubber, various forms of piled or napped fabric including velvet, plush and other materials having naps of fine fibers projecting to a substantial degree above the base fabric may be employed. If a fabric having a pile is used, the pile may be of wool, nylon or other fibers which tend to project substantially from the fabric and which preferably do not lose all of their stiffness or resilience when immersed in paint or other coating materials.

It will also be apparent that the covering 22 may be of felt, of wool, rabbit fur or the like. As previously stated, however, cellular materials, such as foamed rubber or most especially foamed polyurethane resin, arepresently preferred.

In the event that the covering 22 is of a foamed material, such as foamed rubber, or foamed polyurethane resin, it should be of a very soft, pliable character and preferably does not have a Pandux value much above zero. For example, it may be in a range of about to 10 and not over 15. In any event, this cover should have such degree of flexibility that it will easily deform even under moderate pressures involved in a brushing operation to conform to the surface being treated and to squeeze out coating material. The core 21, however, imparts sufficient springincss to the body to prevent it from becoming unduly flabby when it is impregnated with paint or other coating material. Needless to say, the covering should be of a material which does not readily dissolve in the solvents and dispersing agents employed in the coating composition.

The cellular coating layer 22 may be of any appropriate thickness provided it is sufficient to provide an adequate cushioning layer over the core. The thickness seldom will be much less than about a quarter of an inch and may be considerably greater dependent upon the size of the applicator and the work which it is designed for. Thicknesses up to an inch or even greater may sometimes be desirable. For applications of coating materials to broad surfaces such as walls or the lik it is desirable that the lower extremity of the covering 22 be continuously curved in the manner indicated in Figs. 2 and of the drawings in order to obviate sharp angles or edges, which by dragging over the surface to be coated might produce lines in the film. This flexing process tends somewhat to stretch the outer surface of the covring at the tip. The maintenance of the rounded contours at lower extremity of the covering layer 22 is facilitated by the bluntness or curvature of the tip portion of the core element 21. This bluntness or curvature is fur-- ther of value inasmuch as it presents a bearing surface which is yieldable and is of considerable area as com-- pared by that presented by a sharp edge portion of a solid core. The latter type of termination for the core is objectionable inasmuch as it greatly increases the Wear upon the lower portion of the covering element and results in quick failure of the unit.

In some instances, the covering element 22 may be formed by cutting a unit of suflicient area from a long strip or a sheet of soft cellular plastic material or other porous paint carrying media as herein described. The sheet used should be cut to appropriate thickness in well-known manner, for example, by slicing or by application of an abrading element such as a sanding disc,- sanding belt or other device adapted to cut the cellulated plastic to proper size and form.

It is desirable that the outer surface of the covering- 22 be formed of cells having portions sectioned away toprovide a superficial layer of open, capillary cells so that the paint or other coating composition can readily enter into and be retained by the cell. The caviar-like cells of a diameter of about 0.05 inch or even less, obtainable in foamed polyurethane resins are beautifully adapted for the purpose. The cells may also, at least to a certain degree, have intercommunicating passages into the interior of the layer, thus increasing capacity to take up paint. This, however, is not essential since considerable amounts of liquid coating compositions are taken up in the open cells at the surface and when the body is brushed across a surface to be coated, for example, in the manner illustrated in Fig. 15, the composition is transferred to said surface in a highly uniform manner. The tendency of the cells of the covering layer to collapse under the brushing pressure facilitates the transfer by squeezing out any of the composition which may have penetrated relatively deeply into the covering structure.

At the interface of the covering layer and the core, there preferably is provided a relatively impervious, fairly tough skin or pellicle, such as is formed on surfaces of polyurethane resins, either when said resins are formed with the surface in contact with a mold surface or when the surface is left free from solid contact. In any event, it is desirable that this skin or pellicle be retained to provide a barrier to the inward transmission of the coating material from the covering layer to the inner core. It is preferable, from the standpoint of uniformity of behavior of the applicator, that the core be maintained in its dry, unpermeated state. This prevents flabbiness and assures uniformity of flexing of the applicator body. In some instances, however, unprotected cores have been provided which, although initially of a degree of stiffness exceeding the optimum, soften as they become permeated, to a state more practical for coating operations.

It will be apparent that the skin or pellicle barrier at the inner face of the covering layer may also be provided by coating the foamed plastic from which the covering layer or the core are formed of a material, such as a cement of rubber, rubber chloride, nitrocellulose, Vinylite or the like, designed to bridge across the open cells or to permeate the latter to a superficial degree in order to provide a skin and thus to bar inward permeation of coating material into the interior of the core. This material may also be used to bond the core and the covering together.

It is also desirable that the edges of the core be provided with a sealing skin or pellicle, for example, such as the natural skin of the foamed material or a coating of other materials. The trapezoidal core may be completely coated on all surfaces, for example, by spraying or by dipping or immersion in a suitable liquid material adapted to dry and thus to provide the desired covering.

The cores may also be formed by pouring liquid foamable material, such as a mixture of a polyhydric (e.g., a polyester) component and a diisocyanate (e.g., a tolylene diisocyanate) component into a mold of suitable shape. The composition or mixture will then react to form a foam filling the mold and will have upon all surfaces a pellicle which can be retained upon the core and provide a barrier between it and the cover of the finished applicator body.

In order to prevent entrance of coating composition to the face of the core by penetration of the composition between the inner face of the covering and the contiguous face of the core, it may be desirable that the two bodies be cohered, as for example, by a suitable cementing material indicated at 24 in Fig. 2 or by forming one of the

elements

21 or 22 as a separate unit and then foaming and curing the other element in place, so that coherence at the interface is attained. For example, it is not precluded to form the core element by molding the unit or by slicing from a bar or strip and to insert the element in a foam-forming mixture in an appropriate mold and then after the mixture has bloated and set to its final state, the resultant body comprising a core and covering foamed in situ thereabout may be removed from the mold. The core and the covering are cohered but a barrier to permeation remains at the interface. The pellicle upon the outer surface of the covering as thus formed may be removed to provide open celled surfaces that will take up and transfer paints by a suitable slicing or abrading operation as for example, by holding the surfaces of the body in contact with a sanding belt or other abrad ing element.

It is also not precluded to provide a suitable cup of soft flexible foamed material having an appropriate Pandux value and then partially to fill it with foam forming mixture (such as mixture of a polyester containing hydroxyls and an isocyanate) whereby to form a core for the structure. In either event, the preformed material of either the core or the covering is effectively bonded to the material which was foamed in contact therewith to provide eflicient union between the two types of foam and also to establish a barrier to permeation of coating composition between the covering and the core.

It is further not precluded to form cover units of greater width than the cores from sheets of foam material having a skin upon one side. The units are doubled with the skin side in and the lateral edges are cemented together in a butt joint to form a pocket into which a foamed core can be inserted and cemented in place. The use of several of these techniques in the fabrication of applicator bodies having barriers between the core portion and the covering portion is diagrammatically illustrated in certain figures of the drawings to be described.

A handle element suitable for manually holding the applicator bodies as herein disclosed for various coating operations, may be of various forms. The handle element is secured at one end to the base portion of the body element so that the body element projects as a thickened, but flexible, spatulate portion from the end of the handle, and is adapted to flex about said end in a direction perpendicular to the median plane of the said body element. The embodiment of handle illustrated in Figs. 1, 2 and 15 is particularly satisfactory because it is extremely light in weight, is simple and inexpensive to manufacture and applicator bodies may be inserted and removed therefrom with a minimum of time and effort. This construction shown at 30 in Figs. 1 and 2 may be formed of sheet aluminum, steel, plastic or other convenient material, though from the standpoint of lightness of weight, low cost and other factors, sheet aluminum is considered to be excellent. This handle constructed as indicated at 31, comprises a pair of opposed plates conformed, for example, to the outline of a conventional paint brush handle and having edge portions 32 bent inwardly at an angle, e.g., at right angles to the main bodies of the plates, in order to increase rigidity and to obviate sharp edges that might occasion discomfort to the user. These plates 31 may be either joined, or separated at their upper tips, as may be convenient. The lower extremities are broadened to paddle form as in dicated at 33 and preferably are of approximately the same width as the plastic applicator body to which the handle is attached. The lower edge of each portion 33 preferably is inwardly bent as at 34 to provide a flange portion adapted to bite into the upper portion of the foamed material constituting the body in order securely to hold the latter in position. If desired, the portions 34 may also be serrated to provide teeth further biting into the foam to obtain greater security of grip.

Any convenient traction means for obtaining gripping pressure upon the portions of the applicator body between the two paddle-like portions 33 may be employed. For example, rubber bands may be snapped around the constricted portion 35 of the handle, thus providing an exceedingly simple traction device drawing the two halves of the handle together upon the upper extremity of the applicator body. A somewhat more sophisticated securing device is illustrated in the drawings and comprises a sleeve 36 which is threaded at opposite ends for screws 37 extending through openings in the plates 31 at a short distance above the upper end portion of the body 20, to draw the two halves of the handle together. If desired, the head portions 38 of the screws may be slotted as indicated at 39 to receive a screw driver or other instrument designed to provide a purchase for turning the screws as may be required to tighten or loosen the grip upon the applicator body.

Figs. 3 and 4 of the drawing illustrate still another embodiment of handle which may be obtained at relatively slight expense and which is also quite eflicient in operation. This handle, indicated at 41, may be formed of Wood or metal, though preferably it is formed by molding from plastic, such as phenolic resin, urea resin, sheet steel, sheet aluminum, or other appropriate plastic material. The handle may be a solid unit, but for purpose of reducing weight and also for decreasing costs, it is preferably formed as a hollow shell having wall 41a. This shell at its lower extremity, is slotted or split along its sides as indicated at 42, thus giving a certain degree of springiness to the lower portion. The lower portion may also be flared to spatula form as indicated at 43. Usually, this portion corresponds to the width of the applicator body. The spatula portion 43 may be inserted in a conventional ferrule 44 (an operation which is facilitated by the springiness imparted by slots 4'2) where it is held by friction, or by cement, or in any other convenient manner.

The upper extremity of the applicator is forced into the socket thus formed and is held in position (at least partly) by the friction generated by compression of the plastic foam of the covering element and the core. In order to increase the security of holding, the upper extremity of the body may be pierced by transverse pins indicated at 46. The ends of these may be left sharp so that they tend to bite into the plastic walls of the handle element and thus to lock the upper portion of the body in the socket. In those instances in which replaceability of the applicator body by other bodies from time to time or after a body has been used, is not a prerequisite, the body may also be held in position by application of cement in a well-known manner.

The modified embodiment of the invention illustrated in Figs. 5 and 6 of the drawings comprises an applicator body 50 having a covering portion 51, preferably formed of a foamed plastic material such as foamed rubber or foamed polyurethane resin. Such covering may be molded to desired section, or a block of foamed material may be cut in a manner subsequently to be described to provide a cavity designed to receive a core 52 formed of a somewhat stiffer plastic material than the portion 50. In this construction, the covering 51, suitably formed by molding or cutting, is cohered to the core 52, as, for example, by a suitable cement 53 or by forming one portion (51 or 52) as an initial step and then molding the other in situ in or about the first portion.

The covering 51 is of quite soft, flexible, foam material which surrounds the core on all sides except at the upper (butt) end. The impermeable layer 53 between the inner surface of the covering and the outer surface of the core effectively provides a barrier against the ingress of any liquid coating material to the core, with resultant loss of resiliency of the latter.

In forming coverings such as 52, it is also within the purview of the invention to fold a sheet of foamed plastic of suitable length and then to cement the folded portion at their lateral edges in such manner as to provide a pocket which will slip over the core and which can be cemented upon the latter.

At its upper end, the applicator body thus formed may be provided with a handle which, as illustrated in the drawings, substantially corresponds to the handle illustrated in Figs. 1, 2 and 15 and is indicated by the reference numeral 55. Since the operation of the handle is essentially the same as that already described, further reference thereto is not deemed to be necessary.

Some steps in the formation of applicator bodies comprising a soft flexible outer pocket or cup-like covering portion and a springy inner core cohered together are further illustrated in Figs. 7, 8, 9, 10, 11 and 12. In the construction as illustrated in Fig. 7, a mold 60 of cup-like section may be provided. The liquid foamable mixture in suitable amount is introduced into this mold and a solid, non-adherent plug 61, substantially corresponding in size and shape to the core of the applicator body to be formed is inserted. The foam forming mixture as at 62 is poured in and allowed to expand and to cure about the core, thus providing a cupped body of soft flexible material of a Pandux of to 15 and constituting a covering element for the applicator body. If the mold 6t) and the plug 61 are suitably coated with a parting agent or are formed of a material non-adherent with respect to the foam, the cupped foamed body 62 formed in the mold may be extracted and the plug 61 may be withdrawn. As indicated in Fig. 8, the cupped portion 62 is then partially filled with foam forming mixture of proper type. The latter is then allowed to foam and bloat to fill the cavity left by the member 61. The mixture in the cavity when it is adequately cured, provides a suitable, flexible, springy core element 63 which is encased on all sides except at its upper end by the covering element. A barrier to the inward permeation of coating material through the covering into the core is set up at the interface between the covering and the core. same time, the core and its covering are effectively bonded together as a coherent unit.

A body thus formed may be removed from the mold and the outer faces may be cut, as by abrasion, to obtain any desired form and so to open the cells at the faces that they will take up and transfer a liquid composition used for coating purposes.

Any desired handle structure such as illustrated in Figs. 1, 2, 4 or in Figs. 3 and 4 may be applied to this applicator body. It is also within the purview of the invention as illustrated at 66 in Fig. 8 to insert the lower extremity of a spatulate handle element of wood or other material into the upper extremity of the cavity left by the core 61. The mixture constituting the core 63 in foaming, invests and adheres to the lower extremity of said element 66, thus providing an inexpensive handle.

In the embodiment of the invention as illustrated in Figs. 11 and 12, a pocket or liner 70 is provided. This may be of polyethylene, a plastisol comprising a dispersion of polyvinyl chloride in dioctodecyl phthalate, vinyl At the chloride-vinyl acetate interpolymer, rubber, rubber chloride, regenerated cellulose, or a foil of aluminum. It may be indented or ribbed to increase flexibility and improved bond with the foams. Preferably, this liner is quite thin and may be formed by doubling a sheet of the plastic or other material in well-known manner. It is also not precluded to form such liner by spraying or dipping a suitably conformed core into a solution or melt of the plastic material. The formed liner can be stripped from the core.

The preformed liner is inserted in a cup-like mold 71 (see Fig. 11) having a shape corresponding or substantially corresponding to the core element to be formed.

Foam forming mixture in liquid state, is introduced in requisite amount and is allowed to foam and cure in wellknown manner to provide a core 75 of relatively springy, foamed plastic which is encased on all sides except the upper end in a thin envelope of non-cellular plastic material constituting an effective barrier to the introduction of coating material.

The core of springy foam having a Pandux hardness in a range of about 40 to about 90, and having an impermeable coating can be covered with various thick, soft permeable materials. For example, the covering 72 may be of soft flexible polyurethane resin or a foamed rubher as already described. Likewise, as already described, it may be of Dynel, a material having a pile or nap such as velvet or a plush material, felt or any other material having a capacity for picking up and spreading coating materials.

A completed unit is illustrated in Fig. 12, the covering 72 being separated from the foamed core material by the liner 70.

The soft, foamed covering may also be formed by suitably folding a simple sheet of soft foamed materiai or of one of the other permeable materials such as foamed rubber, velvet Dynel or the like, previously referred to, about the core in the manner illustrated in Figs. 1, 2 and 15, preferably with an appropriate cement as a bonding agent between the two.

In the construction illustrated in Fig. 12 as shown at 73, a handle may be provided by molding the lower extremity 74 thereof in the foam constituting the core 75. This construction is further illustrated as being provided with shoulder portions 76 abutting against the upper surface of the core material. This is a somewhat more elaborate construction than that described in connection with Fig. 5.

Cupped covering elements for the applicator bodies can be formed by methods other than casting, for example, in Figs. 9 and 10 is illustrated a method of forming cupped elements from preformed foam blocks and in which a plastic core can be molded or into which a preformed foamed core can be inserted and cemented. In this embodiment of the invention, a block 79 of soft flexible foamed material suitable for use as a covering element for the applicator body is pressed against a revolving abrasion wheel 80 upon a suitable shaft 81. The pressing operation may be preformed by holding the block 79 in a cupped element 82 designed to compress the sides of upper portions of the block of foamed plastic material. The block is also pressed downwardly to a substantial degree so that when the block is released after the abrading operation it springs back as shown at 83 in Fig. 10 to its original dimensions and a cavity 84 of substantially greater depth than the radius of the abrading element engaged is left. A core may be inserted and cemented in place in such cup or foamable mixture may be poured therein and the core allowed to foam up and cure in situ. The resultant body can be supplied with a handle in the manner already described.

The formation of a composite body of foamed material suitable for use as a paint applicator by provision of a cup-like covering element of highly flexible foam into which the material adapted to foam to provide a 9 springy core is poured, has been described. It has al.- ready been indicated that the converse of this operation is also contemplated. Such technique is illustrated in Fig. 13 of the drawings. As shown in this figure, a mold 90 is provided and may be formed of high melting polyethylene, a polymerized fiuocarbon, or any other appropriate material either with or without a suitable lining of a parting material such as silicone resin, as may be required. An applicator core of springy foamed material and of substantially trapezoidal section, is indicated at 91 in this figure and is supported appropriately centered in the mold 90. A foam-forming mixture 92 (shown in Fig. 13 in partially foamed state) of a polyhydric material and a reactive diisocyanate, is introduced into this mold in sufficient quantity to fill the space between the core when it has sufliciently bloated and cured. The core is held in place during the bloating and curing stage by means (not shown). When the cure is completed, the resultant composite foamed article is removed, the skin upon the outer surface is removed as by cutting, or by abrasion and the resultant body is mounted upon an appropriate handle (examples of which are shown in Figs. 1, 2, 3 or 4) to provide a useful paint applicator. Obviously, the handle could also be molded into the core in the manner already described, if so desired.

In Fig. 14 is illustrated still another technique for forming springy flexible cores for the applicator bodies as herein described. In this technique a bar or loaf 100 of springy,,fiexib-le core material of cellular structure and of a Pandux value of about 40 to about 90 is provided. This bar or loaf is covered with its natural skin. It is a height and width approximating those desired in the core elements to be formed. In order to form individual core elements, the bar is subjected to a slicing operation, as for example, along lines 101. If the slicing instrument such as a knife or band saw is inclined at proper angle with respect to the axis of the bar or loaf of foamed material, wedges of trapezoidal section suitable for use as the cores of the applicator bodies are obtained. Assuming that the bar employed has retained its natural skin surfaces, it will be apparent that the resultant cores will be provided with sealing skins or pellicles around their edges and these pellicles provide barriers against edgewise permeation of the coating material being applied. Coverings of soft (Pandux -15) material may be cemented to or otherwise bonded to the cut surfaces to provide applicator units.

In the applicators as illustrated in the drawings the bodies are shown as being of substantially greater width than thickness. This is the more common construction,

however, the width may be greatly reduced if desired. The bodies may even be of substantially equal width and thickness.

The tips of bodies are shown as being rounded. This contour has advantages in laying down very smooth, mark-free films. However, in applying coatings in angles and corners it may be advantageous to give the tips of the bodies a wedge shape or even a pyramidal shape adapting them to work into the angles or corners. As indicated by broken line at X in Fig. 6 one or both of the edges of the bodies may even be cut away to provide an edge conforming to angles of walls to be coated, thus providing a device that will lay down smooth films on broad surfaces and which will also work in angles or corners. As will be apparent from the foregoing description, the utility of a foamed material for use in the practice of the present invention is dependent primarily upon the physical characteristics such as density and more especially, softness or springiness of the foam and resistance of the foam to the action or vehicular components of the coating material being applied. Naturally, some foamed materials may not be useful as applicators in some coating compositions owing to the tendency of the vehicles or the Solvents employed therein to act upon the plastic of the foamed material to an excessive degree. However, such foams may be entirely satisfactory when employed in applicators for other types of coating materials which do not contain components interacting with the plastic. The preparation of polyesters of this type and the further reaction thereof with tolylene diisocyanate to form foams that can be used in this invention is described in considerable detain in copending application, Serial No. 716,292, filed by Louis R. Le Bras et al., February 20, 1958.

The following constitutes essentially a transcript from said application of a specific example illustrating the preparation of a very soft polyurethane resin suitable for use as the covering element for a paint applicator embodying the present invention and being useful in a wide variety of coating compositions. The polyhydric component of the polyurethane resin preferably contains as its dicarboxylic acid member a so-called dimer acid which is obtained by Diels-Alder addition reaction of linoleic or linolenic acids or mixtures thereof. The polyester is made up by esterification reaction of about 70 parts by weight of dimer acids such as Emery Industries acid 30658 and about 30 parts of triethylene glycol. A small amount, e.g., 1 percent or 2 percent of tri methylol ethane may also be included though it is not essential. The resultant mixture of dimer acids and polyols preferably is cooked in a well-known manner to a hydroxyl value of about 60 and an acid value of about 3 or less.

In order to form a foam from this polyester, it is emulsified with a small amount of water, and a tertiary amine as a catalyst to make up one package (A) of a foamable mixture. An appropriate mixture comprises;

An appropriate tolylene diisocyanate component comprises a mixture of about percent 2,4-isomer and 20 percent of 2,6-isomer sold commercially under the trade name of Hylene TM. The catalyst may be conveniently any well-known tertiary amine. Appropriate amines include: triethyl amine, n-methyl morpholine, and the commercial product sold as Dabco which is of the formula:

| 1170 ogt lrn H. CH2 on,

Emulsification of the several ingredients can be accomplished without emulsifying agents. However, a small amount, e.g., about 0.1 percent to about 2 percent of an emulsifying agent such as a conventional soap, or an emulsifier such as Gardinol, Tween 40, Triton X-100, or the like may be added if desired. Other emulsifying agents include gelatin and other materials too numerous to mention. The emulsion preferably is introduced into a mold or spread out as a sheet as quickly as practicable and is then allowed to foam and bloat. It may be cured by baking at a temperature of about F. to about 275 F. for a period of one hour.

The resultant foam is exceedingly light in weight, being of a density of about 1 to about 2 pounds per cubic foot. The Pandux reading is about 0.0 to 2.0. This material is exceedingly soft, flexible and light in weight. It has a uniform caviar cell structure in which the cells are of a diameter of about 0.05 inch. Slabs thereof can be cut into sheets 'of athickness, for example, of about inch to about inch to provide excellent coverings for the 11 applicator bodies herein illustrated. The material will take up and transfer conventional coating materials such as paints, varnishes, lacquers, enamels and the like excellently, in fact, as well as or better than a conventional bristle brush costing many times as much.

This foam as an external covering element, can be replaced by any other foam having a range of cellularity and softness approximately of corresponding value. One appropriate alternative composition comprises a foam of a polyester of about one mole of phthalic acid, about moles of adipic acid and a polyol such as trimethylol propane in an amount to give a hydroxyl value in a range of about 50 to 80.

Still another appropriate polyester comprises adipic acid, 16 moles; diethylene glycol, 18 moles; glycerin, 1 mole. This mixture is esterified to a hydroxyl value in a range of about 60 to 80, a viscosity on the Gardner- Holdt scale of Z Z These polyesters can be mixed with a small amount of water and a tertiary amine to provide a package, which, when incorporated with tolylene diisocyanate, foams to provide useful flexible products that can be used as coverings for applicants applicator bodies.

More rigid, springy foams suitable for use in the cores of paint applicators can be formed from similar polyesters but with the proviso that the hydroxyl value is increased to a range appropriate for reaction with tolylene diisocyanate to give a Pandux reading in the foam product in a range of about 40 to 90 and preferably in a range of about 50 to 80. This is usually eflected by adjustment of the polyol content to give a polyester having a hydroxyl value in a range of about 100 to 200. Such polyesters react with the diisocyanate to give products bordering on semi-rigidity and being useful as core elements in the applicators of this invention. Hydroxyl value is controlled, as is well understood, by regulation of the amount of polyol and the ratio of diol to triol or higher polyol entering into the polyester; the higher the ratio of polyol to diol, the higher the hydroxyl number of the resultant polyester.

The following is an illustrative example of the preparation of a relatively springy type of foam suitable for use as the core element of applicants applicator body.

This prepolymer is mixed as Package B with a premix (Package A) of the same polyester. The premix comprises:

Parts by weight Polyester 80.00 Didecyl phthalate 10.0 Water 3.0 Triethyl amine 0.8 N methyl morpholine 1.8

The mixture of the two packages cures with or without heat, e.g. at a temperature of about 220 F. The foam has a Pandux reading of 73 and a density of 2.8 pounds per cubic foot.

It is well adapted to rise as the core elements in the applicators herein disclosed.

The polyester employed comprises:

Pounds Dimer acids (30658) 49.0 Diethylene glycol 14.0 Trimethylol propane 7.0

This mixture is catalyzed with 0.54 gram of stannous chloride and is cooked to an acid number of 0.54 and a hydroxyl value of 130.8.

A prepolymer is made up comprising:

Parts by weight Polyester 43.5 Tolylene diisocyanate 56.5

The prepolymer is of an isocyanate equivalency of 195.

Tolylene diisocyanate comprises 80 percent of -2,4-isomer.

The didecyl phthalate is a plasticizer and is optional.

12 7 Other catalysts than triethyl amine and N-methyl mor pholine may. be used.

Cements which may be employed to bond the core elements and the coverings of flexible material together in the applicator bodies or tocoat the lateral edges of the bodies include various relatively flexible cementing materials such as rubber cement, cements of chlorinated rubber and the like. One very convenient material comprises so-called plastisols which are emulsions of a polyvinyl halide such as polyvinyl chloride and a plasticizer therefor, one representative plasticizer being diisodecyl phthalate. The cementing materials may also be employed to coat the edges of the applicator bodies or the cores employed therein for purposes of preventing permeation of coating materials into the core with the resultant changes in the flexing characteristics thereof.

The forms of the invention as herein shown and described are by way of illustration. It will be apparent to those skilled in the art that numerous modifications may be made therein without departure from the spirit of the invention or the scope of the appended claims.

We claim:

1. A paint applicator comprising a body element which is a thickened, spatulate form, and having a tip portion upon one end adapted to be brushed upon a surface to be coated, and a base portion upon the other end, said base portion being fixed upon one end of a handle, said body element comprising a core of a foam material having a Pandux reading in a range of about 40 to about 90, and a covering thereupon of a foam material having a Pandux reading in a range of about 0 to about 15, the faces of the core exposed to paint in the use of the applicator being substantially covered with a material which is impermeable to said paint when the body element is dipped therein, the body element being adapted to flex perpendicularly to the plane thereof when the tip portion is pressed against a surface to be coated.

2. A paint applicator comprising a body element which is of a thickened, spatulate form, and having a tip portion upon one end adapted to be brushed upon a surface to be coated, and a base portion upon the other end, said base portion being fixed upon one end of a handle, said body element comprising a core of a polyurethane resin which is of a Pandux value in a range of about 40 to about 90, and a covering thereupon substantially completely enclosing the core and being of a polyurethane foam of a Pandux value in the range of about 0 to about 15, the core and the covering being adhered together as a unit, the core being substantially completely covered by a material which is impervious to permeations by paint when the body is dipped therein in use, the body element being adapted to flex perpendicular to the plane thereof when the tip portion thereof is pressed against a surface to be coated.

3. A paint applicator comprising a body element of a thickened, spatulate form, having a tip pontion at one end and a base portion at the other, the tip portion being adapted to be brushed upon a surface to be coated and the base portion being fixedly secured upon the end of a handle, said body element comprising a core of springy, foam material having a Pandux value in a range of about 40 to about and being of trapezoidal section, the small end of the trapezoid being at the tip of the body element, and a covering of soft, flexible foam material substantially completely enclosing the core and a layer of material impermeable to paint between the core and the covering, and being adhered thereto and protecting the core from contact with the coating material upon all faces exposed to paint, the body element being adapted to flex perpendicularly to the handle when the tip thereof is pressed against a surface.

4. A paint applicator comprising a body element which is of thickened, spatulate form and having a tip portion upon one end thereof adapted to be brushed upon a surface to be coated, and a base portion upon the other end, said base portion being fixed upon one end of a handle, said body element comprising a core of a foamed material having a Panclux reading in a range of about 40 to about 90, and a covering thereupon of a soft, flexible material permeable to and adapted to take up paint and to distribute the same upon a surface and having a Pandux reading in a range of about 0 to 15, the face of the core exposed to paint in the use of the applicator being substantially completely covered with a material which is impermeable to said paint when the body element 10 is dipped therein, the body element being adapted to flex perpendicularly to the plane thereof when the tip portion is pressed against a surface to be coated.

References Cited in the file of this patent UNITED STATES PATENTS Johnson Aug. 20, 1935 Hollenbeck May 12, 1942 Jacoby May 24, 1955 Slinglufi' Oct. 29, 1957 Hacklander Mar. 17, 1959 Hilton Nov. 17, 1959 FOREIGN PATENTS Great Britain Oct. 6, 1954 Great Britain June 19, 1957