US2148137A - Covering structure - Google Patents

Description

Feb. 21, 1939.

D. H. SPITZLI COVERING STRUCTURE Filed May 14, 1936 FIG.

wmmmB-m l N V E N TOR 00mm H- SPITZL! A TTORNE Y Patented Feb. 21, 1939 PATENT OFFICE 2,148,137 oovnnmc STRUCTURE Donald H. Spitzli, Arlington, N. J., asslgnor to Congoleum-Nairn Inc., a corporation of New York Application May 14, 1936, Serial No. 79,672

14 Claims.

This invention relates to structure for sheet coverings suitable for floors, walls, furniture and the like or other rigid or structural surfaces, which coverings have a sheet-like body portion and a cementitious portion which is adapted to bond the body portion to a sub-surface. This invention relates especially to ready-to-lay covering structures of the linoleum or felt base type which carry preformed and integral therewith a cementitious material adapted to bond the covering to a sub-surface.

It is a purpose of the invention to improve upon covering structures of the type above mentioned in important respects which are pointed out below in connection with the following description of certain embodiments of this invention.

In accordance with the present invention a covering structure is afforded which includes, in addition to a sheet-like body portion, a composite cementatory portion.

In order to facilitate an understanding of certain of the features and advantages of this invention, a specific embodiment thereof will be described for the purpose of illustration. For example, the body portion may be similar to that used in ordinary covering structures of the linoleum or felt base type and may comprise a sheetlike foundation member of strain-resisting material, such as woven fabric, or impregnated felt, and integral with one side of the foundation member a decorative and wear-resisting surfacing material such as linoleum composition, paint, or other molded or'coating composition. Integral with the opposite side of the foundation member is a composite cementatory portion of the structure which includes a first layer of a permanently plastic cohesive material and a second layer of a normally nonsticky cementitious material which is on the side .of the first layer remote from the foundation member and which is adapted to be activated to impart thereto adhesiveness so that the covering structure can be permanently bonded to a sub-surface. When the material of the second or outer layer is referred to as normally non-sticky, it is understood that the material in its normal condition is so non-sticky that, without activation, it will not afford a permanent bond between the covering structure and a sub-surface. Preferably the normally non-sticky material is such that the covering can be rolled up into rolls without having the non-sticky cement adhere to any portion of the decorative surface of the covering with which it comes into contact. However, a material possessing, under normal conditions, a'

slight stickiness which is insufficient, without activation of the material, to securely bond the covering to a sub-surface but which is undesirable for rolling and shipment, although it can be overcome by a thin application of soap, wax, or the like, is'to be considered as normally nonsticky. In the embodiment which is now being described for purposes of illustration, the material of the normally non-sticky layer is adapted to be activated by water, to impart thereto adhesiveness, and after activation is adapted to set to a rigid or relatively rigid cement and to firmly bond the covering structure to the sub-surface when the covering structure is laid in place. The material of the permanently plastic layer is, on the other hand, substantially water-insoluble and is adapted to bond the body portion of the covering structure to the layer of normally nonsticky material so that the body portion of the covering structure will be retained in place under normal conditions of traffic, temperature and humidity. However, the cohesiveness of the permanently plastic layer and its bond to the normally non-sticky layer is such that when the covering is pulled from the sub-surface, the cleavage will be at this layer of permanently plastic material and preferably the permanently plastic material will tend to cling primarily to the body portion of the covering rather than to the layer of normally non-sticky cementitious material.

The advantages of a structure of the character aforesaid are many and relate to the suitability of the preformed article for packing and shipment, to the facility with which the covering structure may be laid, to the character of the union of the structure to a sub-surface, and to the manner in which the covering can be removed from a sub-surface when replacement is desired.

Heretofore difllculty has been encountered in removing from a sub-surface a covering (e. g. of the linoleum or felt base type) that has been bonded to the floor, for example, by a rigid type of cement. Such rigid cements of this type are extensively used and are desirable from the point of view of securely and uniformly bonding a floor covering to a sub-surface. However, when attempt is made to remove a floor covering thus bonded to a sub-surface, the body portion of the floor covering frequently breaks or splits into lamina so that complete removal of the floor covering is attended with much difiiculty, excessive labor cost, and frequent injury to'the sub-surface to which the covering was attached. This is particularly true in the case of floor coverings having as a foundation bitumen impregnated felt.

The use of a rigid cement in bonding the body portion of a covering structure to a sub-surface, also results in further difliculties. Thus subsurfaces, such as wood, tend to expand and contract, being particularly affected in this regard by varying humidity conditions. Moreover, concrete sub-surfaces occasionally crack. When the body portion of the covering structure is bonded directly to the surface of the sub-structure by a rigid cement, the movements on the sub-structure impose great strain on the covering. Especially when the sub-structure is of wood there is a tendency for the covering to crack when the boards shrink, the cracking of the covering not only making the covering unsightly, but also introducing a hazard of tripping and permitting cleansing agents to penetrate the covering and cause disintegration thereof- If, on the other hand, the covering itself does not break or crack upon movement of the sub-surface relative to the covering, there is likelihood that the bond between the covering and the sub-surface will break down leaving the covering disunited from the sub-surface. This is particularly likely in those cases, where a felt lining is employed between the covering and the substructure.

This invention has the advantages, among others, that it affords means for successfully eliminating the foregoing difliculties. After a covering structure of the character above described, for example, has been bonded toa sub-surface by activating the layer of normally non-sticky cementitious material with water, placing the covering on a sub-surface and permitting the activated cementitious material to set to a rigid cementitious mass, it can be quickly and readily stripped off even after having been in place for many years, the layer of permanently plastic material insuring cleavage at this layer. While the layer of normally non-sticky material remains bonded to the sub-surface, it can simply and easily be removed from the sub-surface by thoroughly wetting and washing it off by any suitable means such as a brush.

A covering structure embodying this invention, such as the embodiment herein above described, has the further advantage of affording a plastic bond between the body portion of the covering and the sub-surface to which the covering is secured and of preventing movements of the subsurface from being communicated to the body portion of the covering structure with such force as to injure the body portion of the covering structure. For example, a covering structure embodying this invention has been bonded directly to a sub-structure made of wood, the wood thereafter being subjected to widely different conditions of humidity. In such case the plastictiy of the intermediate layer between the rigid cement and the body portion of the covering permitted movement of the sub-surface relative to the covering without injury to the covering structure and without breaking down or weakening the bond uniting the covering to the sub-surface.

With further reference to the character of the bond between the sub-surface and the body structure of the covering, it is an additional feature of this invention that a plastic cleavage layer is afforded while at the same time retaining to a large degree certain advantageous properties of a rigid bond between the body portion and the subsurface. If the cementitious material were solely of a plastic and permanently sticky character, the necessarily substantial thickness thereof would make the surface covering subject to indentation. On the other hand, a rigid cement has the advantage of preventing heavy localized pressures, such as imposed by articles of furni- I than if the bonding cement were composed entire- K ly of permanently plastic material and not perceptibly more than if a rigid cement were used alone. At the same time the normally non-sticky rigid cementitious material affords a permanent and strong bond between the covering structure and the sub-surface and is of such character as to resist deformation of the type that permits indentation of the covering structure.

It is a further feature of the present invention that a ready-to-lay floor covering, having the advantages of a layer of permanently plastic cohesive material on the back of the body portion thereof, is afforded which can be conveniently manufactured, shipped, marketed and laid in place. Thus a covering made according to this invention is distinctly preferable to a floor covering carrying a plastic adhesive which is covered by a protective sheet such as a sheet of paper or fabric treated to make the sheet impervious. In the first place, such sheets serve no useful purpose other than as a protection for the adhesive during shipment and storage and presents an item which is of considerable expense but which does not contribute in any way to the flooring when laid in place. Moreover, such protective sheets add both to the bulk and to the weight of the covering during shipment and render the covering more difficult to make up into rolls for shipment without injury to the goods. Furthermore, additional difllculties are encountered when detachable covering sheets have to be removed to expose the adhesive at the time of laying as the sheets are dimcult to detach without tearing and the careful removal of the covering sheet necessitates considerable labor expense.

With a covering structure embodying the present invention it is possible to make up at the factory a covering which carries a layer of permanently plastic cohesive material, but which, without the use of a detachable protective sheet, presents a back surface that is non-sticky and en ables the goods to be readily made up into rolls and shipped with a minimum of bulk and weight. But even greater advantage and convenience results when it is desired to lay the covering structure. Referring to the embodiment hereinabove described, for example, all that is required when it is desired to lay the covering is to moisten the back thereof with water to impart adhesiveness to the normally non-sticky external layer and then lay the covering in place on a suitable sub-surface. This operation can be carried out very easily and very quickly with a minimum of labor and expense.

Still another important feature of the present invention is that the improved ready-to-lay covering is substantially more flexible than is the case where the normally non-sticky relatively rigid cement layer is in direct contact with the foundation member. Thus the intermediate layer of permenently plastic cohesive material permits some slippage between the layer of relatively rigid cement and the foundation member when the goods are rolled, unrolled and handled in the usual course of manufacture and installation.

In usual practice of this invention the layer of normally non-sticky cementitious material is of such character and thickness that during the process of laying it is merely activated to impart thereto adhesiveness, litttle or none of the adhesive being washed away, and this adhesive in itself affords a firm bond with the sub-surface.

However, it may be noted that when the covering of this invention is made up with the normally non-sticky material applied directly to substantially the whole surface of the permanently plastic layer, it is such that if the normally nonsticky layer should be washed away (as by application of too much solvent) so that one or more portions of the permanently plastic material is exposed, the permanently plastic material will nevertheless afford a bond at such points between the body portion of the covering and the subsurface. Where thenormally non-sticky cementitious material of the surface layer remains, it will, of course. act to bond the covering to the sub-surface. It is likewise of advantage to have the layer of non-sticky material directly adherent to the layer of permanently plastic material so as to reduce as much as possible the amount of material which remains bonded to, the floor after separating the body portion from the floor at the layer of plastic material and which subsequently has to be removed. It is most desirable for example, to leave only a layer of water-dissoluble cementitious material on the sub-surface after removal of the rest of the covering structure so that it can be removed merely by wetting it and washing it off.

In the practice of this inventio'n the body portion of the covering structure may assume several different forms. For example, the body portion may comprise a fibrous sheet of woven fabric, such as burlap, in integral relation with a layer of linoleum composition as in linoleum of usual type. In such case the fabric acts as a foundation member for the decorative and wear-resisting surfacing layer comprising linoleum composition.

The foundation member that is used may alternatively consist of a fibrous sheet of felted fabric such as flooring felt impregnated with a suitable bituminous saturant as is well known in the art. Moreover, other sheet-like strain-resisting materials or compositions may be used which preferably have such properties as resistance to tearing, to stretching, and to distortion by compression. The foundation member may also comprise one or more layers as may be desired, such as-a layer of woven fabric combined with a layer of impregnated felt, for example.

Instead of linoleum composition the surfacing material may consist of a 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, and which is wear-resistant or decorative or both. The use of drying oils, such as linseed, China-wood, perilla, etc. as a base for wear-resistant and decorative compositions is well knownas is likewise the use of soluble cellulose derivatives, such as cellulose nitrate, cellulose acetate and the like. Synthetic resins of the phenolic 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 in the practice of this invention.

In addition to the foregoing, the body portion of acovering structure embodying this invention may consist of other sheet-like coverings such as a fibrous sheet of felt, for example, without an upper surface layer, the felt being either unimpregnated or impregnated with a suitable waterproofing saturant such as bituminous saturant. Such a covering structure, namely, consisting'of an unsurfaced fibrous sheet of felt as a body portion together with a composite cementatory portion of the character herein described integral with the one face thereof, can for example, be used by itself or in conjunction with a linoleum or felt base covering either cemented to the felt or otherwise laid over the felt after the felt has been laid in place. As further modification both faces of such an unimpregnated or impregnated felt may be coated with a composite cementatory portion of the character described. The body portion of the covering structure can also consist merely of a single sheet of material that is wear-resisting or decorative or both, the composite cementatory portion of the structure being adherent integrally with such body portion. Various materials can be used in the different layers of the composite cementatory portion of the covering structure of this invention. A typical example of a permanently plastic layer is a mixture of rubber, preferably crepe or smoked sheet, and rosin, to which preferably there is added a suitable rubber anti-oxidant such as phenyl-alpha-naphthylamine or di-beta-naph- -thyl-para-phenylene-diamine to prolong the duration of the plastic property of the rubber or rubber rosin mixture. Fillers or pigments may be employed if desired, also softeners for the rubber or rosin or both. Among the preferred softeners which have been used are the zinc chloride double salt of phenyl hydrazine, mixtures of light mineral oil and sulfonated petroleum products, and petrolatum. The following is illustrative of a satisfactory material for use as the permanently plastic cohesive layer:-

Per cent Rubber 43.0 Rosin 43.0 Anti-oxidant .2 Softener 5.8 China clay 8.0

The purpose of the different components of the composition will be explained more fully below.

The foregoing illustrative composition for the permanently plastic cohesive layer is substantially insoluble in water. For use with a water insoluble permanently plastic layer, such as that above mentioned, it is preferable to employ in the normally non-sticky cementitious layer on the opposite side of said first layer from the body portion of the covering, a material which is adapted to be activated by water to impart thereto adhesiveness. A typical composition afiording such a cement 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.

The application of the different layers of the composite cementatory portion of the covering structure may be accomplished in any suitable way. Thus, the first layer may be applied directly to the foundation member of the body portion. The ingredients of the permanently plastic layer may first be worked together using calender rolls or a blade mixer and then applied by heating the material until its cohesiveness is substantially reduced and by spreading it on the back of the foundation layer in azrv suitable way, as by means of a doctor blade. In the case of the compostiion illustrated above, it has been found that it can be readily applied by first heating it.

to about 260 F. to 320 F. and then spreading it with a sharp-edged doctor blade, the doctor blade being preferably heated to approximately the same temperature as the material being spread therewith. Preferably also the body portion of the structure is also heated during the coating operation, linoleum, for example, being heated to about 150" F. to 160 F. The material is spread so that the weight of applied material will be 0.01 to 0.1 pound per square yard, very desirable results being obtained when the weight of the layer is about .05 pound per square yard, for example.

After the permanently plastic layer has been applied the layer of normally non-sticky cementitious material can be applied directly over the permanently plastic first layer either immediately or after an interval of time. For this purpose a paste is prepared comprising two to three parts of the above mentioned clay-lignin-glycerine mixture and one part of water. This composition is doctored or otherwise spread onto the back of the linoleum leaving, for example, about .5 to 1.5 pounds per square yard of this cement. Upon evaporation of the water a uniform layer of nonsticky, non-tacky, cementitious material integral with the back of the first layer of permanently plastic material is obtained.

Alternatively, the layer of permanently plastic material can be applied by dissolving the material in a. suitable solvent for the rubber-rosin mixture, such as gasoline, naphtha, benzol, toluol, carbon-tetrachloride, or the like. The solvent can be worked mechanically into the non-volatile ingredients of the permanently plastic material until the desired degree of fluidity is obtained and the resulting solution can then be coated on the back of the body portion of the covering. Upon evaporation of the solvent a layer of permanently plastic cohesive material is afforded which can subsequently be covered with a second layer of normally non-sticky cementitious material as above described,

The foregoing materials are especially desirable for the composite cementatory portion inasmuch as they afiord a preferred arrangement of relative rigidity and relative strength. The claylignin-glycerine mixture affords a relatively rigid and strong bond between the covering structure and the subsurface while the permanently plastic layer affords the advantages hereinabove mentioned. The expression relatively rigid is employed herein to indicate that the normally nonsticky cementitious layer when hardened has a hardness and resistance to distortion substantially equal to or greater than those properties of the body portion of the covering structure. While it is preferable that the normally non-sticky cementitious material be relatively rigid, this is not essential. In this connection, for example, certain advantages of this invention are afforded when the layer of normally non-sticky cementitious material has substantially greater rigidity (less plasticity) than the layer of permanently plastic material. The cohesive strength of the plastic composition above described is substantially less than that of clay-lignin-glycerine mixture in its normal condition.

From the point of view of preventing rupture of the body portion of the covering upon expansion and contraction of a sub-structure, to which the body portion is bonded by the composite cementatory portion, the "cohesive shearing strength of the plastic layer, namely, the cohesive strength of the plastic layer against gradual lateral slippage of the body portion relative to a sub-structure such as caused by expansion and contraction of the sub-structure relative tov the body portion of the covering, should be substantially less than the lateral tensile strength of the body portion of the covering, namely, the tensile strength of the body portion in a direction in the plane thereof. This is especially desirable when the body portion of the covering has little elasticity as, for example, in the case of linoleum comprising a woven fabric or a bitumen-impregnated felt as a foundation member, and a decorative and wear-resisting surface layer of linoleum composition.

From the point of view insuring desired cleavage of the covering structure when it is desired to remove the covering structure from a sub-surface to which it is bonded, it is preferred that the bonding strength afforded by the first layer of permanently plastic material between the second layer and the body portion of the covering be substantially less than the transverse tensile strength of the body portion as a whole or of the foundation member of the body portion of the covering. This is significant in achieving the ready removal of the entire body portion of the covering structure from a sub-surface along a plane of cleavage afforded by the permanently plastic layer. The removal of the body portion of the covering from the second layer of cementitlous material which remains adherent to the sub-surface may be because of separation of the first layer of plastic material from the second layer by breaking the bond therebetween, or be- 40 cause of the separation of the first layer from the body portion by breaking the bond between the first layer and the body portion, or because of separation occurring at an intermediate portion in the thickness of the first layer, or because of successive separations at such places. The transverse cohesive strength of the plastic layer is preferably substantially less than the transverse tensile strength of the body portion of the covering structure as a whole or of the foundation member thereof, such as bituminized felt, woven fabric or the like. By transverse cohesive or tensile strength is meant the strength of the sheet-like portion or portions of the structure in the direction of the thickness thereof,

such as that which resists rupture or lamination when the covering is pulled from the sub-surface to which the second layer is bonded by a force applied to a marginal part of the covering so as to pull the covering away from the sub-surface. Moreover, the bonding strength between the first and second layers of the composite cementatory portion is preferably slightly less than the bonding strength between the first layer of permanently plastic material and the body portion of the structure. This feature is advantageous for the reason that it tends to cause the layer of permanently plastic material to adhere to the body portion of the covering structure when it is desired to remove the covering structure from the sub-surface. It is also desirable that the transverse cohesive strength of the permanently plastic layer be slightly greater than the bonding strength between the permanently plastic layer and the normally non-sticky layer in order that the surface of the normally non-sticky material may be left as clean as possible when the coverin structure is removed from the sub-surface to which it has been bonded. From another point of view it is desirable that the bonding strength between the permanently plastic layer and the normally non-sticky layer be substantially less than the transverse tensile strength 'of the body portion or of the foundation member of the body portion.

when it is said generally that the bond afforded by the first plastic layer between the second layer and the body portion of the covering structure is less than the tensile strength of the body portion, it is understood that the tensile strength of the body portion (including the foundation member when a composite body portion is used) both laterally and transversely is greater than the bond which is afforded by the plastic layer and which is resistant to gradual lateral slipping of the body portion relative to, and to pulling the body portion away from, a sub-surface to which the second layer is adherent.

Some of the reasons for the foregoing relationships may be explained as follows: especially when a permanently plastic material that is water insoluble is used in conjunction with a water-soluble normally non-sticky cementitious layer, it is desirable that as little as possible of the permanently plastic material adhere to the water soluble cement which remains on the floor when the rest of the covering structure is removed, so that such water soluble cement may be the more readily removed. In this connection a materal, such as the clay-lignin-glycerine mixture above referred to, can be readily softened with water so that it may be washed ofi and in this sense is dissociable in water. Any other material which is wholly or partially soluble in substantial degree would likewise be dissociable so that it can be removed by application of an appropriate solvent thereto.

The foregoing desired relationships are inherent when a permanently plastic material of the character above illustrated is used in conjunction with the normally non-sticky cementitious material that has also been illustrated. The characteristics of a permanently plastic layer of the character above mentioned can be varied as may be desired by varying the composition. In this connection the amount of rosin that is used affects the cohesive strength and plasticity of the permanently plastic layer and the adhesion or bonding strength of the layer to adjoining materials, relative increase in the amount of rosin tending to increase both such cohesion and such adhesion. For example, the amounts of rosin and rubber can be varied preferably from about 67% rubber to 33% rosin to about 40% of rubber to 60% of rosin. The cohesive strength of the permanently plastic layer can be decreased by the addition of petrolatum or other non-hardening oil, preferably mineral oil, to the material. This type of softener material is preferably used in amounts less than of the total mass. The presence of a material such as petrolatum also serves to decrease the adhesion of the normally plastic layer to adjoining materials. Other softeners also facilitate the spreading of the material on the body portion of the covering. Thus, if it is desired to reduce the cohesion of the permanently plastic layer without proportionally decreasing the adhesion of the layer to adjoining materials, a softener for rubber such as zinc chloride phenyl hydrazine or sulfonated petroleum oil may be used in increasing amounts.

If, on the other hand, it is desired to increase the cohesion of the layer of permanently plastic material and decrease somewhat the adhesion of this layer to adjoining materials, a filler, such as ochre or china clay, may be used. The adhesion of the permanently plastic layer to the body portion of the covering structure can be promoted by having the surface of the body portion to which the permanently plastic layer is applied of a fibrous character, such as felt or fabric, so that the permanently plastic material will become keyed into the fibrous material.

The word "plastic as used hereinabove is understood herein to apply to any materal (including a single substance or composition) which, notwithstanding substantial deformation after application, preserves the bond between the body portion of the covering structure and the normally non-sticky cementitious layer. In this connection it is immaterial whether upon deformation of the material the particles thereof merely stretch without breaking apart or break apart and then by self-healing become adherent again. Moreover, the plastic material may or may not possess elasticity, namely, a tendency to return to its original form, although a certain amount of elasticity is normally desirable. 1n referring to the plastic material as permanently plastic, it is meant that the material retains its plasticity for a long interval of time in contrast to a material which hardens to a relatively rigid mass upon evaporation of volatile solvents, for example. In the usual case the permanently plastic layer should retain its plasticity during the normal life of the covering structure under usual conditions of use.

Generally speaking, the material of the nonsticky cementitious layer should preferably retain its non-sticky characteristics under normal conditions of storing, shipping and merchandising and under varying conditions of humidity. Moreover, this material should preferably be readily activated and harden to a rigid or relatively rigid cement. It is also preferable that this material be not affected by alkalis, such as alkali that is encountered when the covering is laid directly on concrete. The clay-lignin-glycerine mixture above mentioned, by way of example, possesses these attributes.

A further illustration of a material which may be used as the normally non-sticky cementitious layer is a mixture of concentrated molasses residue and clay. Concentrated molasses residue is the residue that is obtained after distillation of the alcohol from fermented cane sugar molasses. This concentrated molasses residue (containing about 28% of water) may be mixed with a plastic or semi-plastic clay using about 60 parts of the residue to 40 parts of the clay. If desired, a small amount of an anti- -fermentive agent, such as carbolic acid, may be used. Such a cement is adapted to be activated by water to impart adhesiveness and is water dissociable. It may be spread in place over the layer of permanently plastic material, as hereinabove described in connection with the lignin-clay-glycerine mixture.

If desired, the cementitious material usinglignin as a cementitious base, can be mixed in any desired proportion with the cement using concentrated molasses residue as a base.

As a permanently plastic cohesive material, other materials than the rubber-rosin composition described above will sug est themselves. Thus other resins than rosin can be used for admixture with rubber. If it is desired to decrease the cohesivenes of the permanently plastic layer asoftresinmavbe usedinstead ofrosinorrosin oil can be mixed with the rosin or resin. Soft resinsandmixturesofrosin androsinoilmay be employed alone, but the presence of rubber therewith is regarded as distinctly preferable as the rubber renders the permanently plastic material less susceptible to temperature changes. Some resinous materials such as that known as "Bexin", have some antioxidant properties for rubber and are desirable for use with rubber on this account.

Bituminous materials, such as asphalts and pitches, may be used in the permanently plastic layer, but in this instance also the presence of rubber reduces the extent to which the plastic material is affected by temperature change. Resins may also be mixed with the bituminous materials. .For example, a mixture of 100 parts of steam reduced asphalt having a melting point of 155 F. to 160 F., 45 parts of rubber and 36 parts of rosin may be used.

Drying oil products are also available in a permanently plastic material, such as blown oils, but are liable to gradually harden upon aging. This tendency to gradually harden can be counteracted to a certain extent by the presence of an anti-oxidant. For example, a mixture of 50 parts of rubber, 40 parts of rosin, 20 parts of a drying oil cement (composed of an oxidized mixture of 3 parts of linseed oil and 1 part of rosin) and a suitable antioxidant may be used.

In general, it is regarded as preferable to employ 30% or more of rubber in a permanently plastic cleavage layer in the practice of this invention and further advantages result from the use of permanently plastic cohesive compositions comprising both rubber and resin, especially when the mixture of rubber and resin is used in major proportion.

The materials suitable for a permanently plastic cleavage layer which have been mentioned above are of an essentially water-insoluble character. When the material of the permanently plastic layer is substantially water insoluble it is preferable in the practice of this invention to employ as the normally non-sticky layer a material (such as the lignin-clay-glycerine mixture or concentrated molasses residue-clay mixture referred to above) which is adapted to be activated with water to impart thereto adhesiveness. In this manner the layer of permanently plastic material is more likely to remain intact and is much less likely to blend into the normally nonsticky material and lose its desired plasticity. More generally, it is a feature of preferred embodiments of this invention that the material of the permanently plastic layer is substantially insoluble in a solvent that is appropriate to activate the material of the normally non-sticky layer to impart adhesiveness thereto. While this difference of solubility is preferred, some advantage can be gained by having the material of the permanently plastic layer soluble to a substantially less degree than the non-sticky layer in a solvent that is appropriate to activate the material of the normally non-sticky layer to impart thereto adhesiveness.

A normally non-sticky layer which is adapted to be activated to impart thereto adhesiveness by some non-aqueous solvent may be employed if desired, in the practice of this invention. A typical example of such a material consists of nitrocellulose 25%, rosin 25%, and dibutyl phthalate 50%. Such a cementing material can be prepared by dissolving these constituents in a solvent comprising ethyl acetate three parts, toluol one part, and ethyl alcohol two parts. If desired, pigments may be added. The fluid cement is applied with any convenient ,device such as a roll coater, doctor coater, or spray in the amount of about one pound per square yard, for example. The coating is then dried to evaporate the solvent and leave a uniform, non-sticky, non-tacky layer of cementitious material. The solvent that is used to activate the cement to impart adhesiveness thereto may be the same solvent employed in rendering the same fluid for the purpose of the original application. With such a material as that illustrated above, alcohol or some other non-aqueous but water-miscible solvent is preferred as the activating solvent.

When the material of the normally non-sticky layer is adapted to be activated by a solvent other than water, the permanently plastic layer is preferably composed of material which is water soluble or water dlssociable. For example, a permanently plastic water soluble material may be used comprising glue 100 parts, glycerine 400 parts, calcium chloride 37 parts, water 137 parts.

To assist in an understanding of this invention, one embodiment thereof is shown in the accompanying drawing, wherein Figure 1 is a cross-section of a flooring embodying this invention;

Figure 2 is a cross-section of the flooring shown in Figure 1 when partially removed from a. subsurface, one portion being bonded to the subsurface and another portion being removed from the sub-surface.

In the embodiment shown in the drawing, there is a surface layer Iii of linoleum composition which is wear-resisting and decorative and which is integral with the upper surface of a. foundation member ll composed of impregnated felt. The composite cementatory portion of the flooring comprises a first layer I2 of permanently plastic cohesive material which is integral with the under surface of the impregnated felt foundation layer. On the side of layer l2 remote from foundation member I I and directly applied thereto is a second layer l3 of normally non-sticky cementitious material. The latter layer preferably includes channels or grooves I 4 of a reticulated character on the surface thereof.

A preformed ready-to-lay covering, such as that shown in Figure 1, can be rolled up, shipped, stored and merchandised in the usual way. When it is desired to lay the material, this can be quickly and easily done by cutting the material to desired size, applying a suitable solvent (preferably water) adapted to activate the normally non-sticky layer to impart thereto adhesiveness, as by means of a soft bristle brush and then pressing the material firmly in place. The normally non-sticky cementitious material will thereafter set so as to form a relatively rigid mass strongly adherent to the sub-surface to which it is applied.

In Figure 2, a part of the flooring is shown in bonded relation with a. sub-surface I5 01' a suitable foundation or sub-structure Hi. In this figure, a preferred embodiment of the covering structure of this invention is shown after a. portion thereof has been pulled from the sub-surface. It is seen that the plastic layer l2 affords a line of cleavage so that the body portion of auais'r' the flooring (layers II and II) may be readily removed in its entirety. Moreover, all or at least a majority of the layer i2 clings to the body portion of the covering, thus reducing the amount of the material of this layer that is left adhering to the surface of the second layer II and leaving the surface of layer II so that it can be readily dissociated and removed by' an appropriate solvent, preferably water. The tendency of the material of layer if, when as preferred the material of this layer elasticity, to cling to layer ll during removal of the body portion is illustrated by the temporarily semi-detached material II which after separation has been completed returns largely to its original surface, due to the elasticity of the material.

While it is distinctly preferable to employ in the composite cementatory portion of the covering structure a first layer which is permanently plastic and which is integral with the body portion of the covering structure and a second layer which is on the side of said first layer remote from said body portion and which is normally non-sticky, certain advantages of this invention are afforded, especially from the point of view of afiording a cleavage and a plastic bonding layer while at the same time imparting a considerable amount of rigidity in the composite cementatory portion as a whole, when the two layers that are used in the composite cementatory portion are such that the second layer of cementitious material is normally substantially more rigid (less plastic) than the ocmentitious material of the first layer in its normal condition and/or the cementatory material in the second layer is normally less sticky than the cementitious material of the first layer in its normal condition. For example, certain advantages of this invention are afforded when the cementitious material of the second layer is relatively rigid as defined hereinabove or is more rigid than the foundation member of the covering structure while at the same time the first layer is less rigid than the second layer and is preferably less rigid than the foundation member of the covering structure.

Modifications of the application of this invention will suggest themselves to those skilled in the art and the scope of this invention therefore is not to be limited except by the language of the following claims.

I claim:

1. A preformed covering structure of the character described ready-to-lay in bonded relation to a sub-surface, which comprises a body portion including a sheetlike foundation member and a wear-resisting and decorative surface layer of linoleum composition integral with one side thereof, and a composite cementatory portion integral with the opposite side of said foundation member and adapted to bond said body portion to a sub-surface, said composite cementatory portion including a first layer of permanently normally plastic and permanently normally sticky adhesive material and a second layer of normally non-sticky cementitious material which is on the side of said first layer remote from said body portion and which is adapted to be activated by an appropriate solvent to impart increased stickiness thereto, the bonding strength afforded by said first layer being substantially less than the tensile strength of the body portion, and said first layer being substantially less soluble in said solvent than said second layer.

I 2. A preformed covering structure of the character described ready-to-lay in bonded relation to a sub-surface which comprises a body portion including a sheetlike foundation member and a wear-resisting and decorative surface layer of linoleum composition integral with one side thereof, and a composite cementatory portion integral with said body portion on the opposite side of. said foundation member and adapted to bond said body portion to a sub-surface. said composite cementatory portion including a first layer of permanently plastic adhesive material which contains rubber and a resin and which is substantially insoluble in water and a second layer of normally non-sticky cementitious material which is on the side of said first layer remote from said body portion and which is adapted to be activated by water to impart increased stickiness thereto.

3. A preformed covering structure ready-to-lay in bonded relation to a sub-surface which comprises a foundation member of impregnated felt and a wear-resisting and decorative layer of lineleum composition integral with one side thereof,

and a composite cementatory portion integral a with the opposite side of said foundation member, said composite cementatory portion including a first layer of permanently plastic adhesive material comprising at least about 30% of rubber and a second layer of normally non-sticky relatively rigid cementitious material applied directlyto the surface of said first layer remote from said foundation member and which is adapted to be activated to impart thereto increased stickiness to bond the covering structure permanently to a sub-surface to which it may be applied, the transverse cohesive strength of said first layer being substantially less than the transverse tensile strength of the foundation member.

4. A covering structure of the character described which comprises a body portion including a sheetlike foundation member and linoleum composition integral with one side thereof and forming a decorative and wear-resistant surface of said body portion and a composite cementatory portion integral with the other side of said foundation member and suitable for bonding said body portion to a surface of a sub-structure, said composite cementatory portion including a first layer of permanently normally plastic and permanently normally sticky adhesive material and a second layer on the side of said first layer remote from said body portion and composed of cementitious material which is normally substantially less plastic and less sticky than said first layer and is activatable to impart increased stickiness thereto, the material in said first layer being sufficiently plastic and sufliciently thick to maintain the bond between said foundation member and said second layer upon gradual slippage of said second layer relatively to said foundation member.

5. A covering structure of the character described which comprises a sheetlike body portion including a sheetlike bitumen impregnated felt foundation member and a wear-resisting and decorative layer of linoleum composition on one side of said foundation member, and a composite cementatory portion integral with the other side of said foundation member, said composite cebodyportionandwhlchisdissociableinw the bonding strength afforded by said first layer between said foundation member and said secand layer being substantially less than the transverse tensile strength of said foundation member.

0. A covering structure of the character described which comprises a body portion including a sheet-like foundation member of impregnated felt and a wear-resisting and decorative surface layer which is integral with one side of said foundation'member and which includes as a base material a substancemelccted from drying oils, synthetic resins, and soluble cellulose derivatives, and a composite cementatory portion on the other side of said foundation member, said composite cementatory portion including a first layer of permanently normally plastic and permanently normally sticky adhesive material integral with said foundation member and a second layer which is on the side of said first layer remote from said foundation member, the cementitious material of said second layer being water-dissociable and more rigid than the material of said first layer, the bonding strength between said foundation member and said second layer afforded by said first layer being substantially less than the transverse tensile strength of the foundation member.

'1. A preformed covering structure of the character described ready-to-lay in bonded relation to a sub-surface. which comprises a body portion comprising a fibrous sheet and presenting a wear resistant and decorative surface on one side thereof and which comprises a composite cementatory portion integral with the other side of said body portion and adapted to bond said body portion to a sub-surface, said composite cementatory portion including a cementitious layer of normally non-sticky cementitious material adapted to be activated to impart thereto adhesiveness, and another layer interposed between said layer of cementitious material and said body portion and composed of permanently normally plastic adhesive material of such plasticity and thickness as to permit substantial relative lateral movement between said layer of cementitious material and said body portion while preserving substantially unimpaired the strength of thebond between said layer of cementitious material and said body portion.

8. The preformed covering structure of claim 7 wherein the normally non-sticky cementitious material is activatable by an appropriate solvent to impart thereto adhesiveness and said permanently plastic adhesive material is less soluble in said solvent than said normally non-sticky cementitious material.

9. The preformed covering structure of claim "I wherein the normally non-sticky cementious material is a water-dissociable material adapted to be activated with water to impart adhesiveness thereto and the permanently normally plastic adhesive material is less readily dissociable in water than said normally non-sticky cementitious material and comprises rubber.

10. A preformed covering structure of the character described ready-to-lay in bonded relation to a sub-surface, which comprises a body portion including a sheet-like foundation member and a layer of linoleum composition integral with one side of said foundation member and a composite cementatory portion integral with the other side of said body portion and adapted to bond said body portion to a sub-surface, said composite cementatory portion including a first layer of permanently normally plastic and permanently normally sticky adhesive material and a second layer which is on the sideof said first layer remote from said body portion and which is composed of a cementitious material that is normally substantially less plastic and substantially less sticky than the material of said first layer and which is adapted to be activated by an appropriate solvent to impart thereto increased adhesiveness to bond it to a sub-surface, the said first layer being substantially less soluble in said solvent than said second layer.

11. The preformed covering structure according to claim 10. wherein the bond between said second layer and said foundation member afforded by said first layer is subsetantially less than the transverse tensile strength of said foundation member so that said foundation member can be pulled away from said second layer with cleavage at said first layer without rupturing said foundation member, the adhesive material of said first layer being of sufficient permanent stickiness to permit rebonding said foundation member to said second layer of cementitious material by pressing same together with said ticky adhesive material of said first layer therebetween.

12. A covering structure of the character described which comprises a body portion comprising a fibrous sheet and which comprises a composite cementatory portion, said composite cementatory portion including a first layer of permanently normally plastic adhesive material integral with said body portion and a second layer of normally less plastic cementitious material on the side of said first layer remote from said body portion, the material of said first layer affording a bond between said second layer and said body portion and being of sufiicient thickness and plasticity to maintain the bond between said body portion and said second layer upon gradual lateral movement of said second layer relatively to said body portion while preserving substantially unimpaired the strength of the bond between said layer of cementitious material and said body portion.

13. The covering according to claim 12in which the permanently plastic adhesive material of said first layer contains rubber and a resin.

14. A covering structure of the character described which comprises a body portion and a composite cementatory portion integral with one side of said body portion, said composite cementatory portion including a first layer of permanently normally plastic adhesive material containing rubber and a second layer which is on the side of said first layer remote from said body portion and which is composed of a' cementitious material that is normally substantially less plastic than the rubber-containing material of said first layer, the bond between said second layer and said body portion afforded by said first layer of rubber-containing material being substantially less in strength than the transverse tensile strength of said body portion.

DONALD H. SPITZLI.

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