US2272144A

US2272144A - Covering structure

Info

Publication number: US2272144A
Application number: US349073A
Authority: US
Inventors: Frank M Allen
Original assignee: Congoleum Nairn Inc
Current assignee: Congoleum Industries Inc
Priority date: 1940-08-01
Filing date: 1940-08-01
Publication date: 1942-02-03
Anticipated expiration: 1959-02-03

Description

Feb. 3, 1942. F. M. ALLEN 2,272,144

COVERING STRUCTURE Filed Aug. 1, 1940 Ila #6 INVENTOR FRANK M. ALLEN Patented Feb. 3, 1.942

COVERING STRUCTURE Frank M. Allen, Summit, N. 1., assignor to Congoleum-Nairn Inc., a corporation of New York Application August 1, 1940, Serial No. 349,073

20 Claims.

This invention relates to covering structures and the manufacture thereof. It relates particularly to flexible smooth surface sheet-like coverings suitable for covering floors, walls, furniture and the like, or other rigid or structural subsurfaces, which coverings present on one side a decorative and wear-resistant surface.

Heretofore coverings for floors, walls and the like, have been extensively manufactured comprising a strain-resistant base sheet such as felt thoroughly impregnated with a bituminous binder, or a base sheet such as burlap which may or may not be impregnated with a suitable sizing or binder material. Such coverings also comprise linoleum compositions, paints, lacquers or the like, integrally bonded to one side of the base sheet to afford a decorative and wear-resistant surface. Coverings of this type particularly those comprising an impregnated felt base sheet are dlfllcult to remove when bonded by an adhesive to a structural subsurface. Notwithstanding the difflculties of such removal, coverings having a relatively long-wearing life, such as good grades of linoleum, are commonly bonded to structural subsurfaces by means of adhesive material either applied by hand when the covering is installed or preformed on the back of the covering during its manufacture and activated to render it sticky and adhesive when the covering is to be laid. In such case the advantages resulting from bonding the covering to the subsurface are regarded as offsetting difliculties that are incident to eventual removal of the covering.

Coverings that have considerably shorter life than good grades of linoleum, e. g. floor coverings in which the wear-resistant and decorative surfacing layer consists of a coating of paint or lacquer integral with a strain-resistant base sheet, such as bitumlnized felt, are seldom bonded by an adhesive to a. surface to be covered because of the difficulties incident to the removal thereof. In such a covering the body portion comprises a tough base sheet which is substantially impervious to waterand the surface of which is sealed with an impervious wear-resistant layer. For these reasons it is very difficult indeed to bring any solvent such as water into contact with the adhesive material that bonds the covering to the subsurface and it becomes necessary to substantially disintegrate the covering into shreds in order to remove it from this subsurface. This is a very laborious job and is likely to result in injury to the subsurface to which the covering has been bonded.

Again, it has been found that when covering structures of the type referred to are rigidly or directly bonded to a structural subsurface of wood, damage to the covering often occurs by reason of excessive expansion and contraction of the wood subsurface due to varying humidity conditions. Accordingly, it has been common practice to interpcse a separate sheet of dry unimpregnated felt paper between the covering and the subsurface, the interposed sheet being first bonded to the subsurface and thereafter the covering being bonded to the felt sheet by suitable hand-spread adhesives. Although this practice generally prevents damage to the covering structures, it presents many practical disadvantages. In the first place, the method is expensive and laborious. Secondly, the dry felt interliner being of low tensile strength often laminates or separates under trafflc conditions, thus, destroying the desired bond between the covering and the underfloor. Thirdly, even normal usage causes unsightly indenting of the surface covering since the interposed felt sheet being of considerable thickness (usually .040 to .050 inch) but relatively soft, does not provide a firm underlay capable of withstanding localized pressures to which the surface coverings are often subjected in service. When the felt lining interposed is impregnated throughout with a bituminous mate-' rial, the disadvantages of indenting may not be present but such lining felt can only be removed with the greatest difflculty when the surface covering is taken up and such method of installation is likewise laborious and expensive.

It is a purpose of this invention to overcome difficulties such as those above mentioned and to afford covering structures of the character referred to that can readily be removed from structural subsurfaces to which they have been bonded. It is a further purpose of this invention to provide covering structures of the character referred to which when bonded rigidly or directly to substructures of wood are undamaged by the expansion and contraction of such wood substructures and which absorb all normal expansion and contraction of the wood substructure without materially affecting the overall bond between the covering and such substructures. It is a further purpose of this invention to afford a covering structure that is economical to manufacture and that can be bonded in place, if de sired, very quickly and easily.

It is a feature of this invention that in a covering structure presenting a. decorative and wearresistant surface and comprising a strain-resistant base sheet, the base sheet, while in the form of an essentially unitary felt or the like, comprises dissimilar layers or zones, one layer or zone on the side of the base sheet adjacent the wearresistant and decorative layer, being impregnat-, ed with a binder that affords relatively high in: ternal stren th. and another layer or zone having an internal strength which is substantially less than that of the first layer but, nevertheless, not so weak as to laminate under normal service 0on ditions, It is a further feature of preferred emg' bodlments of this invention that eventhe layer which has the lesser internal strength be so treated as to be water-repellent and to resist water contacted therewith from being drawn into the base sheet by wick action. Further features of this invention relate to the quantities and characteristicsof the binder material or materials and to the manner of impregnating the base sheet with the binder material or materials.

A covering constructed as above described has several advantages. In the first place, it can be made as strong as coverings of similar type having conventional backing sheets that are substantially uniform throughout the thickness thereof. Thus, for example, according to the present invention the base sheet maybe a waterlaid felt which within a zone equal to about /4 of the thickness thereof, is impregnated with bituminous material that is of the type and amount commonly used in bituminired felt base floor coverings. The remaining thickness of the felt is also impregnated with bituminous material but to a lesser degree, yet such portion of the felt contributes materially to the total strength of the backing sheet. However, while the partially impregnated layer or zone of the base sheet has adequate internal strength to resist lamination under service conditions, it does present a cleavage layer at which the covering material will laminate when such covering is deliberately pulled away from a surface to which it has been bonded. Furthermore such cleavage layer or none will absorb all normal expansion and contraction of wood substructure to which the cover-, ing may be bonded, there occurring at most only limited or localized lamination which does not markedly reduce the effectiveness of the overall bond uniting the covering to the substructure. In this way coverings not only of the linoleum type but also of the lighter type wherein a paint or lacquer is applied to the base sheet may be made so that the decorative and wear-resistant surface material and the principal body of the base sheet that is integral therewith will strip oil leaving a very thin residue of partially impregnated felt. This residue can be readily removed by application of water or other solvent accompanied by connection with certain illustrative examples of the practice thereof.

The completed structure may, for purposes of one example, be a linoleum suitable for covering floors, walls, articles of furniture and the like. The wear-resistant and decorative layer may be linoleum composition of any conventional type, e. g. having as a binder a mixture of oxidized drying oil and resinous material and containing suitable fillers such as wood flour or cork, to-.

gether with pigments and the like. The linoleum composition whether in the form of a continuous sheet or in the form of a plurality of inlays is regarded as in the form of a sheet or layer. The linoleum composition may be bonded to the felted base sheet by an adhesive or directly by pressure or in other suitable ways, such felt base sheet being made and constructed however in the manner to be described.

The felt base sheet can best be described by reference to the method of making it. A suitable fiber furnish-such as rag, paper or wood fiber stock, is first formed into a water-laid felt sheet which. may weigh, for example, about pound to about 1% pounds per square yard and be .040 to .080 of an inch in thickness. The felted sheet is then treated by applying to one side thereof an asphalt dissolved in a solvent therefor. The asphalt may, for example, have a melting point (determined by the standard ring and ball test) of about 115 to 200 F. and preferably the melting point is in the neighborhood of about 150 to 160 F. The solution is applied so that at and adjacent the side of v the felt to which solution is applied the felt will contain about 5% to about 20% of the asphalt by weight on the weight of the impregnated felt. In commercial practice about 10% asphalt has been found to be'very satisfactory. To secure the incorporation of this amount of the asphalt a solution of asphalt of any appropriate concentration may be used, c. g. a solution of about 5% to about light mechanical treatment causing such water softening such adhesive so that it may be readily removed.

The covering material likewise can be quickly and readily bonded to a surface to be covered. However because the exposedlayer of the felt base sheet is water-repellent the bonding adheflve which usually contains water does not set with the rapidity that is the case with felt which is substantially dry and unimpregnated. This factor affords sufllcient time before the adhesive has set to permit cutting out portions of the covering andreplacing them with inserts as desired. Moreover. even if the adhesive becomes fully set the cutting out of portions is facilitated ,by the cleavage layer or none. After removal of a portion of an lnstalled covering bonded by an adhesive that has set any residual felt and binder is readily removable in the manner above descrlbedandinsertsmaybeputin. Thus,itis

bonded to a surface to remove portions of the coveringandputininserts.

tor the purpose of affording a better under- 25% concentration. A solvent such as naphtha may be used, although any other suitable solvent such as bennol, carbon tetrachloride or the like,

may be used. The. asphalt solution can conveniently be applied during the manufacture of the felt as the sheet passes from the heated drying rolls. In such case the solution penetrates very rapidly and the solvent of! very quickly. The solution should penetrate preferably about /4 to through the feltl After a layer or zone at and adjacent one side of the unitary felt sheet has been treatedwith the asphalt solution and the solvent has been evaporated, asphalt in a heat liquefied condition is applied to the opposite side of the felt. Thus asphalt having a melting point of about'l40' to about 200 1''. (preferably in the neighborhood of about to about F.) is heated to a temperature of about 450" F. and the untreated side of the felt is contacted therewith. The heat liquefied asphalt will strike through to the asphalt that has previously been incorporated by solvent in the other side of the felt and some excess should be employed in order to insure that there is no acne of dry or unimpregnated felt between the cone impregnated with the heat liquefied s h lt and the none on the oppodlte side of the felt impregnated with the solvent solution of asphalt. As a result of this treatment the side of the felt to which the molten asphalt is applied will take up about 40% to about 60% of asphalt on the weight of the bituminissd. standingofthisinvention itwillbe described in" layer. In the completed felt base sheet the molten asphalt preferably penetrates about half to three-quarters of the thickness of the sheet.

It is preferable to first apply the asphalt dissolved in a solvent to one side of the felt and thereafter to apply the molten asphalt to the other side of the felt inasmuch as in this way I have found that the distribution of the asphalt in the resultant sheet of felt can be better controlled. However, it is possible to carry out the several steps of impregnation in reverse sequence. F

After the felt has been prepared as above described linoleum composition can be applied to the side ,of the felt carrying the larger proportion of asphalt. The linoleum composition can be applied directly by pressure contact or by means of an adhesive. Preferably, however, the

surface of the felt to which the linoleum oomposition is applied is previously coated with a coat of sealing paint of any suitable type, e. g. having as a binder a drying oil or resin or both together with a filler, the sealing coat being applied as an emulsion or as a solvent thinned coating composition, or in any other convenient way.

In the resulting felt the ashalt occurs throughout the felt but is non-uniformly distributed in the layers or zones as hereinabove described. The layer or zone containing the greater proportion of the asphalt is primarily a strain-resistant layer having high internal strength characteristics that make it suitable as a foundation sheet for the linoleum composition. Thus this layer in itself may have an internal or laminating strength of about 50 to 60 pounds or more per foot of width. While slightly greater or lesser amounts of asphalt can be used in this zone or layer, about 40% to about 60% is preferred so that the zone or layer will have both high tensile and internal strength. Due to the relative heavy impregnation of the felt with the asphalt, this layer of the felt is substantially waterproof so that moisture cannot be carried into the felt, e. g. from an edge of the covering material by wick action.

The layer of the felt containing the lesser amount of asphalt has considerable tensile strength and adequate internal strength to resist lamination under service conditions that would cause the linoleum composition component of the covering to become separated from the subsuface to which the covering is bonded. Preferably the laminating or internal strength of this layer of the felt by itself runs about 8 to about pounds per foot of width. Due to the fact that the asphalt has been applied as a solution, the fibers in the felt carry quite uniformly a thin coating of the asphalt. This is desirable because such asphalt coating tends to make this zone quite water-repellent so that water will not be drawn into this sheet by .wlck

action.

The resulting covering has the advantages above mentioned. It can be quickly and readily bonded to a subsurface by ordinary adhesives and cementitious materials. When the flooring is installed the unitary base sheet not only in the zone containing the larger amount of asphalt but also in the zone containing the lesser amount of asphalt is sufilciently strong to resist lamidrawn into the felt with resultant disintegration of the felt and deleterious eifect on the adhesive used for bonding the covering to the subsurface. When removal is desired the covering upon being pulled from the subsurface to which it has been bonded will laminate at or within the layer or zone containing the lesser amount of asphalt. It is then arelatively simple matter to remove the remainder of the felt and the adhesive remaining on the subsurface by light mechanical treatment and by application of water or other solvent for the adhesive.

There are a number of other ways of preparing the varlated felt base sheet. Thus, for example, instead of applying to the felt asphalt dissolved in a solvent to produce the zone containing the lesser amount of asphalt, such asphalt can be applied as an aqueous emulsion. In this case also the asphalt will be deposited as'a relatively uniform coating on the fibers of the felt so that the zone thus treated will be water-repellent. In this connection it is preferable in producing the layer or zone containing the lesser amount of asphalt to apply such asphalt while carried by a liquid diluent in which the asphalt either is dissolved, or dispersed in an emulsified state.

It is also possible to first impregnate a sheet of felt substantially throughout with a relatively small amount of asphalt, e. g. about 5% to about 20% on the weight of the impregnated sheet, and then apply additional asphalt to one side only of the lightly impregnated felt sheet. In such case a solution of asphalt or an asphalt emulsion can be applied so as to penetrat the felt sheet substantially throughout. Alternatively, the felt can be prepared by a paper-making operation from a furnish containing emulsified asphalt so that the felt as originally formed contains fibers coated with the asphalt deposited thereon from the emulsion. There are several known ways of making a fibrous furnish containing emulsified asphalt and then forming a felt sheet from the furnish, either with or without the employment of some coagulating agent to deposit the asphalt on the fibers.

When the asphalt is applied in an emulsified state as a part of a paper-making operation it is not always necessary that the entire thickness of the resulting sheet should be formed of the fiber-asphalt emulsion furnish. For example, felt and similar fibrous web materials are frequently made on multi-cylinder machines wherein several thin webs are formed on a plurality of cylinders operating from a plurality of furnishes which may be unlike in composition. For example, five such cylinders may be employed, the first two of which are operated to form webs containing fibers coated with asphalt and the last, three of which are operated to form webs of fibers substantially free of asphalt. In such case when the several webs are pressed together while still wet so that the fibers of one web interlock with the fibers of adjoining webs, the resultant unitary felt sheet will contain a layer or zone corresponding to /5 of the thickness of the felt that contains fibers coated with asphalt, and a second layer corresponding to of the thickness of the sheet that may be substantially free of asphalt. Such a felt can subsequently be treated by application of molten asphalt to the layer that is substan tially free of asphalt to incorporate substantially more asphalt in this layer than is contained in the zone or layer on the opposite side.

It is apparent from the foregoing that the unitary sheet need not be of the same fiber constituency throughout. For example when felt is made on a mum-cylinder machine of the character above mentioned the fibers in different furnishes for the different component webs of the resultant felt sheet product of the machine need not necessarily be the same. For example the webs constituting the zone that is impregnated with asphalt to the higher degree can be made predominantly of wood fibers and the webs constituting the zone that is impregnated with asphalt to a lesser degree may be made predominantly of rag fibers. Somewhat more generally the unitary sheet material, as this term is used herein, may be of substantially identical fiber composition and structure throughout or may comprise webs of similar or different fiber composition. or structure that have been brought into such intimate association as by interfeltlng or bonding of juxtaposed surface fibers of the webs that the webs constitute, an integrally united sheet.

It is also possible to make up a sheet of felt impregnated substantially throughout with a relatively small amount of asphalt in the manner described in the application of William Y. Irwin, Jr., Serial Number 286,345, filed April 17, 1939, for Method of recovering waste fibrous materials. As described in this application a papermaklng furnish is prepared containing bituminous material recovered from scrap bituminized fibrous material, together with fibers derived from wood, rags, newsprint or the like, and together with any filler material such as mineral filler, pigments, particles of hardened oxidized oil or the lik that may be present in the scrap. The furnish contains uncoated fibers and the bituminous material is distributed through the furnish in the form of particles so that when a sheet of felt is formed from the furnish by a paper-making operation a major proportion of the'fibers in the sheet are substantially uncoated although the particles of bituminous material distributed throughout the sheet serve to bond the fibers of the sheet together and substantially increase the internal or laminating strength thereof. After the sheet has been thus produced and dried, the felt can be treated on one side as with asphalt in a heat liquefied condition to impregnate a layer or zone of the felt that is at and adjacent one side only of the felt, e. g. in the manner and to the extent described above. Linoleum composition can then be bonded with the side of the felt carrying the greater amount of bituminous material to afiord a preformed covering material of th linoleum type. In the resultant product the layer of the base sheet that contains the asphalt in the form of particles and to which additional asphalt has not been applied is sufficiently strong to resist lamination under ordinary service conditions even though the layer contains a sumta'ntial proportion of uncoated fibers.

The article thus produced, namely, comprising a base sheet containing a layer on the opposite side from the wear-resistant and decorative linoleum layer, that contains a relatively large proportion of uncoatedorganic fibers is regarded as somewhat less desirable than the embodiments of this invention previously described wherein the fibers of the felt, including the layer containing the lesser amount of asphaltic material, are substantially coated with asphaltic material, due'to the fact that when the felt contains uncoated fibers the felt is somewhat absorptive of water so that water in contact with edges of the material, e. g. cleansing water that may penetrate between seams of the installed covering. spreads laterally to an undesirable extent and has a deleterious effect on the felt and on the bonding material in the locality afiected. Any such water absorptiveness can, however, be counteracted by applying a water-repellent material to the portion of the felt containing the uncoated fibers. Thus, a dilute solution or emulsion of asphaltic material could be used in the manner above described, either before or after the asphalt is applied in a heat liquefied condition to one side of the felt, so as to coat the fibers and increase the water-repellency of the fibrous material and increase the resistance of the fibers to water: Alternatively other waterrepellent materials such as wax, rosin sizes, metallic soaps and the like, can be applied to the uncoated fibers to protect and increase the water-repellency thereof.

In my application, Serial Number 268,250, filed April 17, 1939, for Felt lining, I have described improved felt linings adapted to be used in con.- nection with the installation of covering structures. In said application I have referred to lining felt that contains a substantial proportlon of uncoated fibers in a partially bitumlnined layer on one side of the felt as a preferred embodiment due to the fact that in the use of such a lining felt the layer or zone containing the uncoated fibers is protected from cleansing liquids by the more highly bituminized layer and due to the fact that the high water-absorptiveness afforded by the uncoated fibers facilitates the rapid bonding of the lining felt to a surface to be covered. In the embodiments of the present invention, however, wherein a preformed article is manufactured which presents a wearresistant and decorative layer integral with the base sheet, the substantial freedom of both layers or zones of the base sheet from fibers which are water-absorptive, is preferred for the reasons that have been mentioned hereinabove.

In my said application, Serial Number 268,250, filed April 17, 1939, I have described various unitary felt sheet materials comprising layers or zones differently impregnated with bltuminous or other water-proofing materials, and have mentioned that such felt sheets may be made integral with wear-resistant and decorative surfacing material as in the manufacture of a preformed covering structure before the felt is bonded to a surface to be covered and for this reason the disclosure in my said prior application is to be regarded as incorporated herein and this application is to be regarded as a continuation-in-part of my said prior applica- 7 tion.

While mention has been made of applyin asphaltic material in a heat liquefied condition to afford the layer or zone of the base sheet containing the greater amount of asphalt, the asphalt can be applied in any other suitable way, as by the use of a concentrated solution of the asphalt, or a highly concentrated asphalt emulsion. However, the use of asphalt in a heat liquefied condition is an operation that is easier to control in causing the asphalt to become im presnatodinonlyapartofthethiekness oftha felt and is regarded as preferable in the practice of this invention.

As above mentioned, it is preferable that the more highly impregnated layer of the base sheet contain about 40% to about of asphalt and that the less highly immated layereontain about to about 20% of asphalt. This is not necessarily the case, however, as there may be considerable variation in the amount of asphalt or other binder in the different layers. In general, it is desirable that the amount of asphalt in the different layers differ by at least about Preferably the difference in the amount of asphalt in the different layers is about 20% to about 50%. It is usually not desirable that the amount of asphalt in the more highly impregnated layer go below about 30% inasmuch as the use of lesser amounts does not afiord a desired amount of strength for the strain-resistant backing sheet. On the other hand, it is usually not desirable that the amount of asphalt in the layer having the lesser degree of impregnation contain more than about 30% of asphalt inasmuch as the use of greater amounts of asphalt results in increasing the strength of the layer so as to detract from the capacity of the layer to act as a cleavage layer. Such excessive strength can, however, be counteracted somewhat by the use of asphaltic material that is very soft at normal temperatures, but it is more economical to use a lesser amount of asphalt of higher melting point that imparts desired bonding strength when used in similar quantities. The use of a relatively large amount of asphalt of very low melting point, e. g. having a melting point of about 90 to about 110 F., in the layer of felt that is least impregnated could be useful however in affording in the varlated base sheet a layer that is highly resistant to water absorption and at the same t me has a strength factor appropriate for its action as a cleavage layer in stripping the covering from a surface to which it has been bonded. From this ,point of view, it is possible by employing an asphaltic material that has a very low melting point in one layer, e. g. a melting point of about 90 to about 110 F., and by employing an asphaltic material having a much higher melting point, e. g. a melting point of about 180 to about 200 F., in the other layer of the felt, to afford a varlated base sheet in which one layer has relatively low internal or laminating strength, and another layer has relatively high internal or laminating strength when the former layer or zone contains approximately as much bituminous material as the other layer or zone and still afford some of the advantages of this invention. A structure of this type could be conveniently prepared by applying each of the asphalts in a heat liquefied condition, the asphalt of lower melting point preferably being applied at a considerably lower temperature after the asphalt of higher melting point had been applied to the felt so as to penetrate partially through the thickness of the felt. Such a construction is regarded as less desirable inasmuch as the large amount of relatively low melting point asphalt would tend to bleed and would tend to amalgamate with the higher melting point asphalt and thereby weaken the strength of the backing sheet as a whole. It is within the scope of this invention, however, to provide in any manner a unitary felt backing sheet containing one layer or zone having relatively high internal or laminating strength and another layer or zone having relatively low internal or laminating strength, both layers being impregnated with a binder material. Preferably both of such layers or zones should be repellent to water.

The unitary felt sheet is preferably impregnated so that the layer or zone of felt that contains the binder imparting the greater degree of strength, e. g. containing the greater proportion of asphalt, will penetrate about 5 to V4 through the thickness of the felt.

Instead of linoleum composition the decorative and wear-resistant material integral with the varlated base sheet may consist of paint, lacquer, enamel or other suitable molded or coating composition having a drying oil base or other suitable base such as a synthetic resin or a soluble cellulose derivative. The use of drying oils such as linseed, China-wood, perlila, etc., as a, base for water-resistant and decorative compositions is well known as is the use of soluble cellulose derivatives such as cellulose nitrate, cellulose acetate and the like. Synthetic resins of the phenolic type or alkyd type may also be used as or in the binder or vehicle base. Such base materials may be mixed with suitable fillers, pigments and the like, in a variety of compositions that may be used.

The wear-resistant and decorative material may be directly bonded to the varlated base sheet or, alternatively, may be separated therefrom by one or more layers of sheet material such as a woven fabric, paper or the like. Suitable adhesive material such as oxidized drying oils, resins, or mixtures thereof, in a suitable solvent or in emulsion form, may be used to bond the material constituting the wearing layer integrally with the base sheet either directly or with some sheet material of the character aforesaid interposed. Alternatively, in some cases the bonding may be accomplished merely by pressure. Moreover, suitable sealing coatings to prevent the asphaltic material from bleeding into the surfacing material may be employed. In any such case the decorative and wear-resistant coating or layer is regarded as integral with the varlated base sheet and as being bonded to one side thereof.

While in preferred practice it is desirable to complete the preparation of the varlated base sheet before the wear-resistant and decorative surface is formed thereon or bonded thereto, nevertheless, in some cases it is possible to partially treat the base sheet, as by applying molten asphalt to one side, to form the layer or zone of high impregnation and high internal strength, subsequently to form or apply the wearing surface over such layer, and thereafter to treat the opposite side of the base sheet with a solution of asphalt or the like, to render the same waterrepellent and to provide a zone or layer of lower internal or laminating strength as compared with the internal or laminating strength of the layer or zone of the felt sheet adjacent the wearresistant and decorative surface.

One embodiment of this invention which is of particular utility comprises the varlated base sheet in combination with a decorative and wearresistant surface layer comprising a heavy print coat of paint, lacquer, enamel or the like, that may be applied in some ornamental design. The print coat preferably overlies a sealing composition between the base sheet and the print coat.

It is also possible in the practice of this invention to apply decorative and wear-resistant material directly to the base sheet. In fact, the asphaltic material in the layer or zone of felt having the greater internal strength can itself carry pigment material adapted to afford a decorative and wear-resistant surfacing material.

The structure as above described can be made and sold without any coating applied to the back thereof inasmuch as the back of the structure in preferred practice presents a layer of felt that is only lightly impregnated with asphalt. The asphalt in the amount used is sufiicient to prevent the felt from rubbing of! and, at the same time, is relatively small in amount so that the felt appears to be of an attractive grey or brown color and ls relatively non-sticky. For this reason the structure may be made without the expense of a. backing coat, such as is commonli used on the back of asphalt-felt base floor coverlugs, to cover the unsightly appearance oi the black asphalt and to counteract the soiling tendency of the asphalt. If desired, however, a coating, e. g. containing a suitable binder such as drying oil, or resin, casein or the like, together with a filler pigment may be applied to the back of coverings embodying this invention.

Alternatively, a cementitious material may be applied to the back of the structure to afford a preformed covering which can be bonded in place without resort to the use of a cement applied on the job. A typical composition affording such a ceemnt is a mixture of clay 55%, lignin 42%, and glycerine 3%. The term "lignin refers to an article of commerce obtained by evaporation of waste sulphite liquors from the wood pulp industry. About two or three parts of the clay-lignin-glycerine mixture may be mixed with one part of water and applied to the back of the covering leaving, for example, about .5 to 1.5 pounds per square yard on the back of the covering structure. Upon evaporation of the water a normally non-sticky cementitious material remains integral with the back of the coverin structure which cementitious material 'can be activated by water when it is desired to bond the covering structure to a surface to be covered. Such a cement, being water dissociable, is advantageous because when it is desired to remove the covering structure from a surface to which it has been bonded, the structure will laminate .at or within the layer of felt having the lower internal strength and by light mechanical treatmeht and application of water the felt and cement remaining bonded to subsurface can easily be removed.

An adhesive such as that above described may likewise be hand spread on the job to bond covering structures embodying this invention to a surface to be covered. Other adhesive and cementitious compositions may likewise be used in the manufacture of ready-to-lay covering structures with adhmive compositions preformed integrally on the back thereof or on the Job in bonding the covering structure to a surface to be covered.

In addition to asphaltic binder materials other bituminous binder materials may be employed such as a mixture of rubber and resin in about equal proportions and to the extent of ab0ut 5% to about 25% by weight of the impregnated layer of felt containing it. The opposite side of the sheet can be impregnated with about 40% to about 60% of bituminous material having a softening point of about 160 F. to about 170 1". extending about half to three-quarters through the thickness of the felt and at least to the layer impregnated with the rubber-rosin mixture. In such case the layer impregnated with bituminous material gives requisite strength to the backing sheet. The rubber-rosin binder in the other zone or layer constitutes a permanently plastic binder that imparts sufllcient strength to prevent the zone in which it occurs from, laminating under normal service conditions but that is appropriate to permit lamination at or within this layer when it is desired to strip the covering comprising the variated base sheet from a surface to which it has been bonded. Using a base of the character mentioned the wear-resistant and decorative surfacing material is made integral with the side of the felt presenting the asphalt impregnated zone. If desired the side of the felt containing the rubher-rosin composition can be covered with a sealing paint to counteract any stickiness of the rubber-rosin binder. Alternatively, a cementitious material such as a clay-lignin cement can be used to cover the rubber-rosin impregnated layer and to provide a normally non-sticky and water-activatable cementitious backing on a preformed covering structure. In such a structure the felt containing the rubber-rosin binder is advantageous in that it provides a cleavage layer that is permanently of a plastic and resilient character -and that has low temperature susceptibility. It

such as pitches, tars and'the like, in any or each a of the layers of the base sheet. Moreover, other binder materials, preferably having waterproofing characteristics, may be employed in any or each of the layers, such as resins. drying oils, rubber, waterproofed glue, waxes and the like, although bituminous bonding materials are normally preferred. If astrengthening binder ma terial is used which does not have inherent waterrepellent characteristics such as bitumens, waxes and the like, any layer or layers containing such binder material may be treated in preferred practice with a water-repellent material of the character hereinabove mentioned to decrease wettability oi' the fibers and the capillarity or wick action of the felt.

one side with a strengthening binder material is preferable that the binder for the cleavage layer of the variated felt base sheet have some permanent plasticity, that is, the capacity to remain somewhat plastic during the normal life of the covering structure, inasmuch as very brittle and rigid binder materials tendto crumble when subjected to repeated shock. e. g. when subiected to traffic on a floor, with resultant diminution of the strength of .the cleavage layer.

By way of further example, a sheet of felt can be impregnated at and adjacent one side thereof with a drying oil-rosin composition containing pigment, the drying oil-rosin composition penetrating through about half to three-quarters the thickness of the sheet. The remainder of the sheet can then be impregnated with a binder material such as a mixture of glue and glycerine in the proportions of about 1 to 4, together with some hygroscopic material such as calcium chloride. Such a cement affords a binder that remains plastic and when used in an amount such as about 5% to about 25% will give adequate strength to resist lamination in service while affording a cleavage layer when itis desired to strip the material from a surface to which it has been bonded. A sealing coating can be applied to the back of the covering. In this modification the pigmented drying oil-rosin binder applied to the felt constitutes the wear-resistant and ,decorative surface material that is an integral part of the covering structure.

In general, it is preferable that the zone or layer of the unitary variated base sheet having the greater'strength have an internal or laminating strength of about 40 pounds or greater per foot width, and should be from about .025 to about .055 of an inch in thickness. The zone or layer having the lower strength should-preferably have an internal or laminating strength of about 8 to about 20 pounds per foot width and should be from about .010 to about .025 of an inch in thickness. The laminating strength of the two layers preferably should differ from each other at least by about20 pounds per foot width. In order to minimize any' effect of the zone or layer of lower internal strength on making the covering subject to indentation, this zone preferably should not be more than about .020 of an inch in thickness.

By the expressions internal strength and laminating strength as used herein with reference to the character of the several layers or zones within the variated base sheet, is meant the ability of the felt within such layers or zones to withstand internal separation or lamination and is thus distinguished from tensile strength. A measurement of this property may be obtained by firmly bonding to a smooth, flat support'a strip of material, cut to a predetermined width, and then, commencing ,at one end of the strip, applying a uniform pull at right angles to the flat support, noting the force required to separate or laminate the sheet internally.

In the practice of this invention the base sheet that is used preferably comprises felt made from fibers which are normally animal or vegetable fibers, e. g. such as the fibers derived from rags and waste paper, wood, etc., although, of course, mineral fibers may be present. The felt may likewise contain filler materials such as clays and the like. In addition to felt other fibrous base sheet materials may be employed such as fabrics made from loosely spun yarns, etc.

Covering structures that illustrate the practice of this invention are shown in the accompanying drawing wherein Figure l is a cross-sectional view of one form of covering structure embodying this invention;

Figure 2 is a cross-sectional view of a modifled embodiment of this invention comprising a cementitious material integral with the back of the structure;

Figure 3 is a cross-sectional view of an additional embodiment of this invention wherein the wear-resistant and decorative surface layer is embedded in the variated base sheet itself, and I Figure 4 is a cross-sectional view of an embodiment of this invention bonded to a structural surface.

Referring to the drawing (which is not drawn to scale and in which component layers are enlarged for clarity in illustrating structure), the covering shown in Figure 1 comprises a layer of decorative and wear-resistant material It which may be a coating of paint, lacquer. enamel or the like. Between the layer l and the base sheet which is indicated generally by the reference character H, is a thin layer of sealing material II, which may be a paint adapted to prevent the bitumen in the base sheet from bleeding into the layer Ill. The base sheet H comprises the layer Ha which, for example, may contain 40% to 60% of bituminous binder, and the layer lib which may contain about 5% to of bituminous binder.

In Figure 2 the layer 20 is shown as a relatively heavy layer and may be a sheet of linoleum composition. This layer is directly bonded to the surface of the base sheet which is indicated generally by the reference character 2| and which comprises a layer 21a having relatively greater laminating strength than the layer lib, both of the layers being impregnated with a binder adapted to impart the desired laminating strength characteristics to the different layers. Preformed integrally with the back of the covering is a layer of cementitious material 23 which is adapted to be activated to impart stickiness thereto for bonding the structure to a surface to be covered.

The covering shown in Figure 3 comprises the base sheet indicated generally by the reference character 3|. In this modification the binder for the layer Sla of the base sheet carries wholly or partially throughout a material that provides this layer with a decorative and wear-resistant surface. The layer lib of the base sheet has less laminating strength than the layer 3ia. This layer Slb may be impregnated with about 5% to 25% of a rubber-rosin binder material, for example. 0n the back of the covering is a protective coating 34 which may be of any suitable composition.

In Figure 4 the action of the layer of felt having the lesser internal or laminating strength as a cleavage layer is illustrated. The covering is shown as comprising a decorative and wear-resistant layer which -may be linoleum composition, for example. Between this layer and the 'variated base sheet indicated generally by the reference character ll is a thin layer 42 of cementitious material adapted to bond the layer I to the base sheet ll. The layer Ma oi the base sheet has the greater laminating strength and the greater proportion of binder, e. g. bitumen. The layer llb of the base sheet has the lesser internal or laminating strength and contains a lesser amount of binder, e. g. bitumen. The covering is bonded to the surface of a structure l! by a cementitious composition 45 which may be any suitable cement.

One end of the covering is shown being pulled away from the surface of the structure 46 and it is to be noted that the covering laminates intermediate the thickness of the layer lib of the base sheet leaving a small residue of felt bonded with the cement ii that remains affixed to the surface of the structure 48. When the main body of the covering structure has been separated from the surface covered thereby application of a solvent for the cement, e. g water, accompanied by light mechanical treatment will soften the cement and permit ready removal of the cement and remaining felt from the surface of structure 46.

In the drawing the embodiments shown are merely illustrative. The decorative and wearresistant layers. the sealing layers, the backing layers of paint or cement or the like, are interchangeable in the embodiments shown. Moreover, other structural elements may be incorporated in the covering structures. More generally it is to be understood that the structures herein specifically described merely exemplify the practice of this invention so as to afford a clearer understanding of the practice thereof and that the scope of this invention is to be governed by the language of the following claims.

I claim:

1. An integral covering structure of the character described which presents a decorative and wear-resistant surface and which comprises a unitary fibrous sheet underlying said decorative and wear-resistant surface, said unitary fibrous sheet containing binder material throughout the thickness thereof and comprising a strain-resistant zone adjacent said decorative and wear-resistant surface and a second readily laminatable zone disposed more remotely from said decorative and wear-resistant surface than said strainresistant zone, said strain-resistant zone containing binder material in greater proportion than in said second zone, which binder material in said strain-resistant zone imparts to said zone substantially greater laminating strength than the laminating strength of said second zone.

2. An integral covering structure of the character described which presents a decorative and wear-resistant surface and which comprises a unitary fibrous strain-resistant sheet, said unitary fibrous sheet containing water-resistant binder material 'throughout the thickness thereof with the portion of said sheet on the side adjacent said wear-resistant and decorative surface containing a substantially greater amount of binder material and having substantially greater laminating strength than the portion of said sheet on the other side thereof. and said unitary fibrous sheet throughout the thickness thereof comprising substantially the same fibrous material.

3. A covering structure of the character described which comprises a decorative and wearresistant surface layer and integral therewith a unitary felt strain-resistant sheet containing throughout the thickness thereof water-resistant binder material, said unitary felt sheet con taining a zone on the side of said sheet adjacent the decorative and wear-resistant surface layer that contains a substantially greater proportion of binder material and has substantially greater lamlnatingstrength than a zone on the opposite side of said sheet, and the fiber constituents of said unitary felt sheet being substantially uniformly interfelted throughout the thickness thereof.

4. A covering structure of the character described which comprises a decorative and wearresistant surface layer and integral therewith a unitary felt strain-resistant sheet impregnated throughout the thickness thereof with a bituminous binder, said unitary felt sheet containing a, zone on the side of said sheet adjacent the decorative and wear-resistant surface layer that contains a substantially greater proportion of hituminous material than a zone on the opposite side of said sheet and the bituminous material in both layers being distributed substantially uniformly as a coatin on the individual fibers to render said unitary felt sheet water-repellent throughout, and the fiber constituents of said unitary felt sheet being substantially identical in said zones and being substantially uniformly interfelted throughout the thickness thereof.

5. A covering structure of the character described which presents a decorative and wearresistant surface and which comprises integrally united with said decorative and wear-resistatnt surface a unitary fibrous felt backing sheet, said backing sheet containing water-resistant binder material throughout the thickness thereof and said backing sheet comprising a zone on the side adjacent the said decorative and wear-resistant surface that has substantially greater laminating strength and contains a substantially greater proportion of binder material than a readily laming strength.

6. An integral covering structure of the character described which presents a decorative and wear-resistant surfac and which comprises a unitary fibrous sheet underlying said decorative and wear-resistant surface, said unitary fibrous sheet containing water-resistant binder material throughout the thickness thereof and comprising a zone adjacent said decorative and wear-resistant surface that has substantially greater laminating strength and contains a substantially greater proportion of binder material than a second readily laminatable zone more remote from said decorative and wear-resistant layer than said first zone, the binder in said second zone being permanently plastic and the binder in said first zone being substantially more rigid than the binder in said second zone.

7. An integral covering structure of the character described which presents a decorative and wear-resistant surface and which comprises a unitary fibrous sheet, said unitary fibrous sheet being impregnated with a water-resistant binder throughout the thickness thereof and comprising a first zone on one side thereof adjacent said decorative and wear-resistant surface having a laminating strength of about 40 pounds or greater per foot width, and a second zone on the side of said sheet remote from said decorative and wearresistant surface having a laminating strength of about 8 to about 20 pounds per foot width, and said second zone having a thickness of about .010 to about .025 inches and comprising a substantially lower proportion of binder than comprised in said first zone.

8. An integral covering structure of the character described which presents a decorative and wear-resistant surface and which comprises a unitary fibrous felt sheet, said unitary fibrous felt sheet containing water-resistant binder material throughout the thickness thereof and comprising a first zone on one side thereof adjacent said wear-resistant and decorative material that contains at least about 30% of water-resistant binder material and a zone on the opposite side of said unitary fibrous felt sheet that contains not more than about 30% of water-resistant binder material, the difference in the binder content of the two zones being at least about 10%.

9. A coveringstructure of the character described which comprises a decorative-and wearresistant surface layer bonded to a strain-resistant base sheet having substantially the same fiber constituency throughout the thickness thereof, said base sheet being impregnated throughout the thickness thereof with a waterresistant binder and comprising a first zone adjacent said decorative and wear-resistant layer that has substantially greater laminating strength and greater proportion of water-resistant binder material than a second zone disposed more remotely from said decorative and wear-resistant layer. said first zone constituting about to the thickness of said base sheet, and the bond between said decorative and wear-resistant surfac layer and the said zon of said base sheet having the greater laminating strength being substantiatlly greater than the laminating strength of said zone having the lesser laminating strength.

10. A covering structure of the character described which presents a decorative and wearresistant surface and which comprises integrallv united with said decorative and wear-resistant surface a unitary fibrous backing sheet, said back ing sheet containing water-resistant binder throughout the thickness thereof and comprising a zone adjacent said decorative and wear-resistant surface that has substantially greater laminating strength and greater proportion of waterresistant binder material than a second zone disposed more remotely from said decorative and wear-resistant layer, said covering comprising a layer of cementitious material preformed on the back thereof and adapted to bond said covering structure to a subsurface, and the laminating strength of the union between said decorative and wear-resistant surface and said zone of said flbrous sheet having the greater laminating strength being substantially greater than the laminating strength of said zone of lesser laminating strength between said layer of cementitious material and the said zone of said backing sheet having greater laminating strength.

ll. A covering structure of the character described which comprises a decorative and wearresistant surface layer and which comprises a unitary felt backing sheet, said backing sheet containing water-resistant binder material throughout the thickness thereof and comprising a first zone on one side thereof adjacent said decorative and wear-resistant layer containing about 40% to about 60% of a,water-resistant binder and a zone on the opposite side of said backing sheet having substantially less laminating strength than said first zone and containing about to about 20% of a water-resistant binder.

12. A covering structure of the character described which comprises a layer of linoleum bonded to a unitary felted fiber strain-resistant base sheet of substantially the same fiber constituency throughout the thickness thereof, said. base sheet being impregnated with bituminous binder throughout the thickness thereof so that substantially all of the fibers of said felt are coated with bituminous binder and comprising a first zone on one side thereof adjacent said layer of linoleum composition containing about 40% to about 60% of a bituminous binder and constituting about /2 to about the thickness of the base sheet and a second zone on the opposite side of the backing sheet containing about 5% to about 20% of a bituminous binder, said second zone being of a substantial thickness that is less than about .025 inch.

13. A covering structure of the character described which comprises a layer of coating composition that contains asuitable base and a pigment and that is integral with a unitary felted fiber strain-resistant base sheet, said base sheet being impregnated with bituminous binder throughout the thickness thereof so that substantially all of the fibers of said new are coated with bituminous binder and comprising a first zone on one side thereof adjacent said layer of coating composition containing about 40% to about 60% of a bituminous binder and constitut-ing about it to about A. the thickness of the base sheet and a second zone on the opposite side of the backing sheet containing about 5% to about 20% of a bituminous binder, said second zone being of a substantial thickness that is less than about .025 inch, and the libel constituents of said felt base sheet being substantially identical in said zones-and being substantially uniformly interfelted throughout the thickness of said base sheet.

14. In the manufacture of a covering structure of the character described wherein a decorative and wear-resistant surface layer is made integral with a bituminiz'ed felt base sheet, the steps comprising coating the fibers in a zone adjacent one side of said felt base sheet with a bituminous material dispersed in a volatile diluent, removing the volatile diluent, impregnating the felt on the other side of the base sheet with bituminous material in a heat liquefied condition to form a bituminized zone which extends only partially through the thickness of the felt and which contains substantiallymor bituminous material than said first mentioned zone, and making integral with theside of the felt containing the greater amount of bitumen said wear-resistant and decorative surface layer.

15. The process according to claim 14 wherein the bituminous material applied in a volatile diluent is applied dissolved in a. volatile solvent, and the solvent is evaporated.

16. The process according to claim 14 wherein the bituminous material applied in a volatile diluent is applied in an aqueous emulsion and the water is evaporated.

17. The process according to claim 14 wherein the bituminous material dispersed in a volatile diluent is applied to fibers on one side of the felt prior to the application of bituminous material in a heat liquefied condition to fibers on the other side of said felt.

18. A covering structure of the character described which comprises a decorative and wearresistant layer of linoleum and integrally bonded therewith a unitary felted i'lber strain-resistant sheet comprising substantially the same fibrous material throughout the thickness thereof, said sheet containing water-resistant binder material throughout the thickness thereof and comprising a zone adjacent said linoleum layer that has a substantially greater laminating strength and greater proportion of binder material than a second readily-laminatable zone disposed more remotely from said linoleum layer.

19. A covering structure of the character described which comprises a decorative and wearresistant layer of linoleum composition bonded to a strain-resistant backing sheet comprising substantially the same fibrous material throughout the thickness thereof, said backing sheet containing water-resistant binder material throughout the thickness thereof and comprising a first zone adjacent said linoleum layer that has substantially greater laminating strength and greator proportion of water-resistant binder than a second zone disposed more remotely from said linoleum layer, said first zone constituting about one-half to three-fourths the thickness of said backing sheet and said second zone being of substantial thickness but less than about .025 inch.

20. A covering structure of the character described which comprises a decorative and wear resistant layer of linoleum and integrally bonded therewith a unitary felted fiber strain-resistant sheet, said sheet containing water-resistant binder material throughout the thickness thereof and comprising a. zone adjacent said linoleum layer that has a substantially greater laminating strength and greater proportion of binder material than a second readily-laminstable zone disposed more remotely from said linoleum layer.