US2706936A - Anti-skid surface covering - Google Patents

Description

Patented Apr. 28, 1955 2,706,936 ANTI-SKID SURFACE COVERING Gilbert G. Willson, In, St. Paul, Minn., assignor to Minnesota Mining & Manufacturing Company, St. Paul, Minn a corporation of Delaware No Drawing. Application June 21, 1948,

Serial No. 34,3 Claims. (Cl. 94-5) This invention relates to anti-skid floor coverings of the nature of flexible and water-resistant sheet material having a roughened resinous anti-skid surface.

While the product of this invention is of general utility in providing anti-skid surfaces on floors, Stairways, aircraft wing-walks, and the like, it has been found to be t Sliding of ammunition, striking nailed shoes, etc., must cause no sparking, particularly in the vicinity of gasoline or powder storage. The anti-skid surface should not abrade or cut the feet of personnel who must on occasion walk barefoot over it in carrying out their assigned duties. It should be easily cleaned, without excessive wear on mops or brushes.

Softer particulate surfacings in place of the more common mineral abrasive grid particles have found some application in providing anti-skid surfacings. Cork particles, for example, ofler a degree of protection against slippage when properly bonded to the walkway surface. But under the service conditions'encountered on aircraft carriers, anti-skid surfaces containing cork particles are found to be less effective in preventing slipping than those containing mineral abrasive grit. Cork and simi-' lar particulate material swells somewhat under continued exposure to water, and then away from the resinous binder with which it is bonded to the flooring. Furthermore, such anti-skid surfaces even under dry conditions have a somewhat shorter useful life than has the mineral type anti-skid surface.

In a popular type of anti-skid surface covering, hard bonded to a waterproofed fabric base with a binder material consisting largely of a thermally hardened phenolic resin. The sheet material is then attached to the sheet steel, concrete, or other floor or deck surface by means of a suitable tough and adherent adhesive cement. The anti-skid wear-resisting surface is provided by the particles of mineral, the resinof the floor surface with surfaces as the or broken away.

I have now found that irregularly shaped, angular grid particles of procured synthetic resins or analogous bodies having properties of hardness, resilience, toughness and the like as hereinafter defined, and in particular the moulded phenolic resins, may replace the abrasive mineral particles of these prior art anti-skid walkway surfacings, with surprising results in terms not only of anti-skid efiiciency but also in terms of prolonged wearresistance.

I have found that particularly desirable and unexpected results are obtained wh crushed fully cured phenol-aldehyde resin moulding resin applied as a en I employ particulate 0 compositions as the grid material in my-novel resinous anti-skid floor surfacing sheet material. Suitable material is available in large volume from the manufacturers of moulded phenol-aldehyde radio cabinets, telephone hand-sets, and similar objects, in the form of rejected or broken pieces, sprues, fiashings, or the like. These compositions ordinarily contain a high proportion, e. g., 50-80%, of wood flour or other inert filler. They are mouided or cured at relatively high temperatures and pressures, to a fully cured, hard and dense state. As such, they are highly water-resistant.

Cast phenolic resins, which are poured into moulds and then allowed to harden for relatively long times at relatively low or moderate temperatures, have substantially equivalent properties. These and other analogous phenolic resinous products are included within the scope of the term thermally cured phenolic resin mouldings as employed herein.

These relatively massive moulded products may be readily reduced to desired dimensions by free crushing on rolls, followed by screening to desired size. In carrying out these operations, it has been found that materials particles for my anti-skid ducible to the specific dimensions required substantially In contrast, the abrasive minerals, whether natural or synthetic, cannot be reduced to the relatively large-size particles required for anti-skid surfacings without at the same time producing considerable quantities of much smaller particles or fines.

s far as properties of the finished anti-skid article are concerned, the abrasion and impact resistance of the particles is of importance. I have observed without formation of dusts bination of resiliency, toughness, inmpact resistance, and analogous properties of my novel grit materials, as evidenced by their peculiar reaction to crushing, is such that individual grams, while readily broken from the strength. Furthermore, the I substantially no reduction to fines are completely clean and free from surface-adherent dust, so that the resinous binder of the sheet product forms a firm adherent bond directly to the surface of the grain.

In making sheet material suitable for application as anti-skid surfacing, I may proceed as follows: I first take a sheet of cotton drills cloth of any suitable width, and saturate the same, e. thermoplastic resin.

disclosed in the afore-mentioned patents. v

Both surfaces of the treated cloth are next coated with 0.15 lb. per sq. yd. of a soft, adherent phenolic 60% solution in a mixture of water and ethylene glycol monoethyl ether, and the coated sheet is then hung up and heated for 1 /2 hours at synapse a P. The phenolic resin, which thereby only partially cured. providing improved adhesion resin bond.

The resin bond is next applied to one surface of the cloth base, over the last-described coating. This bond consists of 0.139 lb. per square yard of a phenolic resin made from one mol of phenol and 1.4 mols of formaldehyde, with alkaline catalyst, and which is dissolved in a mixture of water and ethylene glycol monoethyl ether. This resin rapidly sets up on heating to provide a hard, tough, and adherent bond.

As soon as the viscous resin bond coat is spead over the treated cloth, the resinous grit material is applied. This grit material consists of crushed and graded moulded phenolic resin; it has a specific gravity of about 1.4, and its surface can be scratched by calcite but not by gypsum. It is supplied as particles of from 56 to 80 grit size, the average being approximately 60. This is approximately equal to the size No. l or No. 1 /2 flint sandpaper. The grit is pressed into the resin bond, and excess grit is shaken off, leaving approximately .54 lb. of grit per square yard. The coated sheet is heated to remove solvent and partially cure the resin bond.

is a slow-curring type, is It acts as a priming coat, between treated cloth and it is then given a surface sizing coat of 0.460.48 lb. per sq. yd. (dry basis) of the same binder material but at somewhat greater dilution. The coated and sized sheet is finally cured for 12-14 hours at 175 F., then for l-3 hours at 212 5., and finally for 4-6 hours at 248 F.

The resulting sheet product is sufliciently flexible so that it may be fitted and cemented to somewhat curved or irregular flight deck surfaces. it is of such excellent waterproofness that it does not soften, nor lose quantities of the resin particles when subjected to foot tra'fiic, after prolonged periods of immersion in sea-water. When secured in position on flight decks or the like, it provides an effective and long-lasting anti-skid surface which does not cause noticeable wear of shoe soles or rubber tires and is completely non-abrasive toward steel cables.

A specific construction has been described which provides properties of particular desirability in connection with flight decks of aircraft carriers. This particular construction is not limited to such applications, but may be employed to advantage in many other locations. For example, the reduction in weight obtained by using my resinous grit in place of mineral type abrasive grit makes the new construction valuable for forming anti-skid walkways on aircraft.

resin particles is important where grit loosened or worn from an adjacent anti-skid walkway might be pressed into contact with polished surfaces or be drawn into bearings, since scratching of such polished surfaces is thereby avoided. The grit-coated surface produces no sparks when struck by steel articles. Workman can safely w'alk bar'efooted 'on such surfaces without discomfort.

Many variations in particularly 'in 'v'iew of the following discussion. any strong and flexible fabric or fibrous sheet may be protected with any suitably flexible, strong, adherent and water-resistant thermoplastic resinous impregnating agent to provide a flexible base for the anti-skid surfacing. Depending on the type of surface to be given anti-skid properties, it may also be possible to form and cure the anti-skid surface on a relatively rigid pie-formed shaped body, or even to form and cure it directly on the base surface, as in the case of wood floors, for example. However, it is ordinarily more convenient, and makes for a much more uniform and superior product, to provide a flexible p're-cured surfacing material such as hereinabove described, and subsequently to cement such product to the walkway surface.

The resinous binder composition nection with the above example is typical of phenolic binders employed in the coated abrasive art, and forms no part of the present invention. Any analogous binder composition providing equivalent adhesion, toughness, water resistance, and other required properties may be used, and many such materials are known 'to the art.

While heavily loaded phenolic or other resinous compositions are not ordinarily suitable as binders and surface sizes due to their greatly increased viscosity, neve'u theless some loading of these materials is possible of grit used in making The nonabrasive quality of the the construction of my novel resinous anti-skid sheet material will become apparent,

Thus,

described in coniii often is advantageous. Wood flour, mineral pigments and fillers, and other inert powders may be used for this purpose. Coloring agents are particularly desirable, in improving the appearance of the final product. Resinous grit such as is here used for the anti-skid layer, but reduced to a much finer particle size, may be added as filler.

With regard to the resinous grit material itself, all things considered, the sized particles obtained on crushing relatively massive thermally cured phenol-aldheyde mouldings containing a high percentage of inert filler and having a Moh hardness value of about 3 are generally to be preferred. Particles of the approximate size identified in the example have been most useful, but a considerable range of particle size, for example from 24 mesh to 150 mesh, is permissible. As hereinbefore noted, a preferred phenolic raw material is available as a waste product from the plastics industry. For special purposes, and where the added expense is of no particular consequence, phenolic mouldings containing a much lower proportion of inert filler, or mouldings containing special types of filler, such as specific colored pigments or fibrous material, or even unfilled moulded phenolic resin products, may replace the moulded radio cabinets, telephone hand sets and the like specifically mentioned herein as source material for my resinous particles. Many examples of such compositions have been found to possess toughness, resiliency, impact resistance, etc. to a desirable degree, particularly as evidenced by their ability to be reduced to desired grit size without excessive formation of fines.

Resins or equivalent materials other than phenolic resins, and having the desired hardness value and crushability factors, may be used in many instances, but are found to be in general less desirable. Thus, aminoaldehyde resin masses having a Mob scale hardness value of about 3 have been reduced to the proper particle size and bonded, by means of phenolic resin binding and sizing compositions, to impregnated fabric, as in the above example. The resulting product was effective as an anti-skid surfacing under dry conditions, but the grit broke up and lost its effectiveness under use conditions involving the continued presence of Water. Furthermore, the sheet material curled when dampened prior to application, and was then difficult to apply smoothly to flat surfaces.

The relative weights, or more significantly the relative volumes, of binding and sizing composition and of resinous grit material may be varied widely in making my improved type of surfacing. Minimum. amounts, both of binder and of surface size, which are required to provide effective anchoring of a desired quantity of resinous particles of any specific diameter or particle size may readily be determined. The product is somewhat more flexible than more heavily bonded sheets, and is also somewhat less costly to produce. increasing the amount of binder increases the number of particles which may be retained per unit area, and also increases the life of the sheet in use. The amount of surface sizing is ordinarily controlled so as to provide complete covering and effective anchoring of each particle without completely filling the valleys between particles. However, where a particularly long-wearing surface is de sired at the expense of a somewhat reduced effectiveness as an anti-skid material, the amount of sizing coat may be increased so as to form a continuous smooth outer surface. Such a product has merit as a long-wearing and fire-resistant floor covering, and has been suggested as a replacement for linoleum. in this type of product, the addition of finely divided resinous filler to the resinous binder and surface size, as hereinbefore mentioned, is particularly appropriate.

My flexible resinous anti-skid surfacing sheet i lay be affixed to flight decks or other surfaces in a number of ways, but I prefer at the present time to employ solventtype adhesive cements for this purpose. One such cement, which has given excellent results for the specific purpose here emphasized, consists of a solution in a volatile organic solvent of a blend of pigmented polymerized chloroprene and a compatible, oilsoluble, heatadvancing phenol-aldehyde resin. T he liquid adhesive cement is ordinarily applied to both surfaces, e. the deck surface and the back of the anti-skid sheet, and is allowed to dry; one or both of these coatings is then re activated, either by heating or by the application of a thin surface coating of dilute adhesive cement or of solvent, and the strip is pressed in place and held until the bond is completed. The surfacing sheet may be furnished to the user as a pro-coated sheet, requiring only activa tion of the adhesive coating by heat or solvent.

The sheet material may also be adherently attached to various surfaces by means of normally tacky and pressuresensitive adhesives. Thus, one type of my anti-skid sheet material is first lightly coated or primed on the back surface with a dilute solution of the polychloroprene-phenolic resin adhesive cement, and is subsequently coated with a heavier layer of a high-strength normally tacky and pressure-sensitive adhesive, which is then protected with a temporary liner such as Holland cloth.

By means of the invention described hereinabove, I provide a new product of widespread utility, and having particular advantages as a component of anti-si id deck surfaces on aircraft carriers. One embodiment of my invention is in the form of a flexible pro-formed sheet ma terial suitable for adhesively bonding to deck surfaces or the like, and having an anti-skid surface layer comprising firmly bonded sized particles of water-resistant thermally cured phenolic resin mouldings. he anti-skid surface thus produced is substantially equivalent in anti-skid prop erties to similar surfaces made with mineral abrasive grit particles, yet has no abrasive action on steel cables. Surprisingly, in spite of the vastly lower hardness or abrasive factor, the new all-resin product is also superior in wear-resistance to the mineral-granule type.

I claim:

1. Flexible unitary sheet material having a rough antiskid surface layer of improved wear-resistance and which is non-abrasive and non-sparking toward steel, said sheet material comprising, in order, a flexible water-resistant fibrous supporting base, a water-resistant non-thermoplastic grit bond, and a layer of firmly bonded, tough and resilient angular resinous grit particles having a Moh scale hardness value of about 3 and a particle size in the range of about 24-150 mesh.

2. Sheet material according to claim 1 and having, on the surface opposite the anti-skid surface, a firmly'bonded non-tacky coating of a solvent-activatible Water-resistant adhesive cement.

3. Sheet material according to claim 1 and having, on the surface opposite the anti-skid surface, a firmly bonded coating of a normally tacky and pressure-sensitive adhesive.

4. A structure comprising a walkway having a surface and, adhesively bonded thereto to form an anti-skid surface covering, sheet material according to claim 3.

5. Flexible unitary sheet material having a rough antiskid surface layer of improved wear-resistance and which is non-abrasive and non-sparking toward steel, said sheet material comprising, in order, a flexible, water-resistant, impregnated fibrous supporting base, a water-resistant resinous grit bond, and a layer of firmly bonded, tough and resilient angular grit particles of Water-resistant, thermally cured phenolic resin having a Moh scale hardness value of about 3 and a particle size in the range of about 24-150 mesh.

6. Flexible sheet material having a rough anti-skid surface layer of improved wear-resistance and which is non-sparking and non-abrasive toward steel, said sheet material comprising, firmly bonded together in the order indicated, a flexible, water-resistant, impregnated fibrous supporting base, a water-resistant phenolic resin grit bond, and a layer of firmly bonded, tough and resilient angular resinous grit particles having a Moh scale hardness value of about 3 and a particle size in the range of about 24-150 mesh.

7. Flexible unitary sheet material having a rough antiskid surface layer of improved wear-resistance and which is non-sparking and non-abrasive toward steel, said sheet material comprising, in order, a flexible, water-resistant, impregnated fabric supporting base, a water-resistant phenolic resin grit bond, and a layer of firmly bonded, tough and resilient angular resinous grit particles having a Moh scale hardness value of about 3 and a particle size in the range of about 50-80 mesh.

8. Flexible unitary sheet material having a rough antiskid surface layer of improved wear-resistance and which is non-sparking and non-abrasive toward steel, said sheet material comprising, in order, a flexible, water-resistant, impregnated fabric supporting base, a water-resistant phenolic resin grit bond, and a layer of firmly bonded, tough and resilient angular grit particles of water-resistant, thermally cured phenolic resin containing about 50-80% of inert filler and having a Moh scale hardness value of about 3 and a particle size in the range of about 50-80 mesh.

9. Sheet material according to claim 8 and having, on the surface opposite the anti-skid surface, a firmly bonded coating of a normally tacky and pressure-sensitive adhesive.

10. Flexible sheet material having a rough anti-skid surface layer of improved wear-resistance and which is non-sparking and non-abrasive toward steel, said sheet material comprising, firmly bonded together in the order indicated, a flexible, water-resistant, thermoplastic-resinimpregnated fabric supporting base, a water-resistant phenolic resin grit bond, a layer of firmly bonded, tough and resilient fully cured phenolic resin angular grit particles having a Moh scale hardness value of about 3 and a particle size in the range of about 24-150 mesh, and a surface sizing layer of phenolic resin.

References Cited in the file of this patent UNITED STATES PATENTS OTHER REFERENCES Ellis, The Chemistry of Synthetic Resins, Reinhold Publ. Corp., New York, vol. 1, 1935, pages 455, 462, 463.

Claims (1)

1. FLEXIBLE UNITARY SHEET MATERIAL HAVING A ROUGH ANTISKID SURFACE LAYER OF IMPROVED WEAR-RESISTANCE AND WHICH IS NON-ABRASIVE AND NON-SPARKING TOWARD STEEL, SAID SHEET MATERIAL COMPRISING, IN ORDER, A FLEXIBLE WATER-RESISTANT FIBROUS SUPPORTING BASE, A WATER-RESISTANT NON-THERMOPLASTIC GRIT BOND, AND A LAYER OF RIRMLY BONDED, TOUGH AND RESILENT ANGULAR RESINOUS GRIT PARTICLES HAVING A MOH SCALE HARDNESS VALUE OF ABOUT 3 TO A PARTICLE SIZE IN THE RANGE OF ABOUT 24-150 MESH.