US2299066A - Method of making molded inlaid linoleum - Google Patents

Description

06f. 20, J BERGER METHOD OF MAKING MOLDED INLAID LINOLEUM Filed Aug. 3, 1940 Patented Oct. 20, 1942 METHOD OF 'MAKING MOLDED INLAID LINOLEUM John L. Berger, Columbia, Pa., assigner to Armstrong Cork Company, Lancaster, Pa., a. corporation of Pennsylvania Application August 3, 1940, Serial No. 350,447

12 Claims.

This invention relates to the manufacture of molded inlaid linoleum. and is concerned particularly with a method of obtaining an improved product having a smoother wearing surface, a denser body, and an improved key to the burlap foundation.

In the manufacture of molded inlaid linoleum, inlaying compositions of various colors are applied through a series olstenils as a loose granular mix onto a burlap backing. The mix is then pressed in a heated at bed press to consolidate the same, reduce it to final thickness, and bond it to the backing. The product is then stoved at elevated temperatures to cure the inlaying com.- positions which are generally composed of oxidized linseed oil, rosin, fillers, such as cork or wood iiour, and pigments.

The binder of oxidized oil and resin is more or less thermoplastic or thermosetting and, in order to prevent adhesion of the mix to the face of the consolidating press, it has been found expedient to interpose a sheet of oiled paper between the face of the mix and the platen of the press. Even with this precaution, the desired heat and pressure necessary to produce a final product having a density and surface finish comparable to calendered linoleum cannot be obtained. When suficient heat and pressure are applied to the mix to eiect the desired result, the mix adheres to the oiled paper and, when it is attempted to strip the paper oil', the mix is loosened from the burlap backing and in some instances is actually pulled completely away. Inrall events', a thin iilm of the surface of the'consolidated mix is imbedded in the paper and is stripped oi with it and, while to the naked eye the surface appears to be smooth, :t nevertheless is somewhat porous and lacquer or wax surface treatments have been resorted to by most manufacturers to seal the surface. When the paper is stripped off, the bond between the paper and the surface of the mix is stronger than the internal bond of the mix. This results in offsetting of the face of the mix as mentioned above and also is sufficient to cause the mix to pull loose Afrom the burlap to` aslight extent at least when the paper is stripped off. If the oiled paper be eliminated, the mix adheres to the press platen under such heat and pressure conditions.

The desired key to the burlap and the desired surface finish have not been attained, apparently because the temperature of the inlaying compositions while disposed in the consolidating press under pressure has never been high enough to admit of any material now of the 'oil and resin 65 binder. High pressure alonewill not eiect the desired result. Attempts to increase the temperature in the platen of the press have always resulted in the difcultyof adhesion of the compositions to the oiled paper."

According to this invention, the temperature'of the inlaying compositions is elevated to such a degree that the plasticity of the binder is reduced and the mix is capable of flowing under condi* ltions of minimum pressure, such pressure being applied by a iiat bed consolidating press but in an amount insufilcient to cause any material olisetting of the compositions onto the oiled paper sheet, if one be used. The product thus treated is then carried to a second press, while still in heated condition, and is further consolidated at a lower temperature and a materially higher pressure, the initial treatment being effective to prevent adhesion of the mix to the surface of the platen of the second press under the final consolidating pressure.

In the accompanying drawing, the ligure is a diagrammatic view of a press arrangement suitable for use in practice of the invention.

In carrying out the invention, the inlaying compositions may be deposited upon a backing such as burlap, in the manufacture of linoleum, or upon a saturated felt web, in the manufacture of linoflor. In the specification and claims, the term linoleum is used for convenience to designate both products. So far as the present invention is concerned, the manner of depositing the granular compositions onto the foundation is not important. It may be applied through stencils by workmen or may be applied mechanically. The whole pattern need not be made of stencilled inlaying compositions-it may include inserts, for

example, of marbleized compositions produced by 1 calendering.

In the gure shown in the drawing, the backing or foundation web has been diagrammatically indicated by the numeral 2 and the layer of granulated inlaying compositions applied thereto has been designated with the numeral 3. For convenience of description, it will be assumed that a web 2 is burlap and the inlaying compositions 3 are made up of areas of granulated inlaying com-` positions covering substantially the entire area of the burlap 2, that the nal web will be embossed in certain design areas, and will have a iinal thickness of about`.0'75 inch. Under such hypothetical conditions, the thickness of the inlaying compositions 3 prior to consolidation may be =222 inch.

The web of burlap 2 carrying the granulated inlaying compositions 3 passes over a card roll 4 which is effective for drawing the backing and the inlaying compositions deposited thereon across the inlaying table for presentation to the consolidating press. The material then passes over a supporting roll 5 and into a consolidating press which is generally indicated by the numeral 6, the press having an upper platen 1 and a lower platen 8. In the embodiment shown, the press 6 is so arranged that the platen 8 is moved vertically toward and away from the Platen 1 by means of a hydraulic ram. Insofar as the process is concerned, however, this particular arrangement is not important. The press 6 is shown in closed position in the drawing. A roll of oiled paper I0 is mounted above the platen 1 and a web, l

II is fed therefrom under the face of the platen 1, over a parting roll I2 to a wind-up roll I3, through appropriate take-up equipment generally indicated by the numeral Il.

In practice of this invention, the platens 1 and 8 are both heated, the platen 1 being heated in the neighborhood of 255 to 270 F. and the platen 8 in the neighborhood of 285 to 300 F. The platens 1 and 8 are parted and the burlap foundation carrying the inlaying compositions to be consolidated is drawn into the press from the inlaying table. An unused portion of the web II of oiled paper is disposed between the face of the platen 1 and the upper surface of Athe inlaying compositions to be consolidated.

The press is closed by ram 9 and a pressure of about 120 poundsper square inch is applied to the material disposed between ythe platens 1 and 8. This application of pressure is continued for about six seconds. Heat from the platens 1 and 8 is transferred to the material under treat'- ment and, at the end of the six seconds treatment, the material will have attained a temperature of about 280 F. At this temperature, the plasticity of the oil and resin binder Yfor the inlaying compositions is materially reduced and the particles seem to flow together into a homogeneous mass even under low pressure, lling the interstices of the burlap and conforming to the smooth surface of the oiled paper.

As the material emerges from the first press, it has been reduced in thickness from .222 inch to .128 inch. The web II of oiled paper is stripped from the face of the consolidated sheet with the aid of the parting roll I2 and the associated wind-up and take-up mechanism Iii-I4. It is observed Yherethat there is substantially no offsetting of the surface of the consodilated inlaying compositions onto the oiled paper sheet and consequently no stress is applied to the layer of compositions which would tend to loosen the excellent key between mix and burlap attained because of the plastic now of the mix at high temperature. The surface presented after the material leaves the press 6 and the oiled paper is stripped therefrom is smooth and i substantially nonporous. The density of the consolidated inlaying composition is not high enough, however, and a second pressing is necessary.

In those' instances where it is desirable to conserve the heat within the web prior to further consolidation, a steam-heated plate I5 may be disposed adjacent the exit end of the press 6. This plate I5 maybe initially heated when the machine is started up and then the transfer of heat from the sheet to the heavy metal of the plate relied upon to present a suflicient heat lag to accomplish the desired result. 'I'he plate I5 may in other instances be eliminated depending upon the temperature of the ambient atmosphere. In my preferred procedure, however, the

plate is heated to 150 to 250 F. so that the temperature of the web as it is fed to the second press is in the neighborhood of 230 F.

'Ihe sheet passes from the plate I5 to a second press generally indicated by the numeral I6 having a heated upper platen I1 and a heated lower platen I8. In the embodiment shown, the press I6 is identical with the press 6. A fabric covered idler roll I9 is provided in advance of the press` I6 and where found necessary or desirable, a ycoating of paraffin oil or a mixture of parafiin oil and linseed oil may be applied to this roll and transferred therefrom to the face of the inlaying compositions prior to entrance into the second press I6. It will be observed that there is no oiled paper protective sheet used in the second press.

In the embodiment under consideration, the platen I1 is heated to between 230 and 260 F. and the platen I8 is heated to between 150 to 259 F. These temperatures are considerably below the temperatures obtaining in the platens of the first press 6. In the second press I6, however, the pressure applied by its hydraulic ram 20 is 1450 pounds per square inch rather than pounds per square inch as used in the first press. The dwell of the second press I6 is the same as the first press, about six seconds. This is effective for maintaining the sheet at about 230 F. during pressing. At this temperature, the binder for the inlaying compositions is still in a plastic condition and flows readily, particularly under the heavy pressure.

Startlingly, no adhesion of the compositions to the face of the plate I1 occurs. The reason for this is not fully understood but it is believed that there may be some surface polymerization of the binder of the inlayingcompositions under the conditions of high heat effected in the first press which creates a skin adjacent the upper surface of the inlaying compositions. Such polymerization or surface curing eliminates a major portion of the thermoadhesiveness and the composition does not adhere to the press platen under the extreme pressure employed. A highly polished surface is provided on the platen as in the first press and it is also possible that some of the oil from the paper II may be transferred to the surface of the compositions and a combination of these factors has created the new result. In any event, if the temperature and pressure treatment of the second press were effected upon an unconsolidated and previously non-heatand-pressure-treated inlaying composition, the material would adhere to the press platen or to the oiled paper sheet if one were used. In other Words, if the first press were heated to the same temperature as the second press and a pressure of 1450 pounds per square inch were appliedl the inlaying composition would adhere to the oiled paper to such an extent that it could not be removed without destruction of the product. The same would be true if oiled paper were not usedthe composition would adhere to the face of the press platen. This does not occur in the present process and it is believed that this is due to the initial heat treatment of the compositions above the so-called flow point of the binder or cement therefor.

The material as it leaves the second press has been reduced to substantially its final thickness which, in the embodiment under consideration, ls .075 inch.

The material is pulled-through the presses 6 and I6 by means of a card roll 2| similar to the roll 4, the material being held against the card roll 2l by a back-up roll 22. Idler roll 23 serves to insure that the material moves freely from the press I6. A dip roll 24 and a positioning roll 25 are provided. The material may be led from these rolls into a curing chamber where the material is subjected to heat for a period of time to properly cure the product.

In the illustrated embodiment, the material passes to an embossing press generally indicated by the numeral .26 which press includes an upper platen 21 anda lower platen 28, the upper platen 21 being provided with an embossing plate having raised portions corresponding to the areas to be indented in the nal product. The embossing may be effected while the material is still relatively hot and no heat need be applied to the embossing plate or to the lower platen 28. It has been found desirable, however, to apply heat to both for with such practice it is possible to take advantage of the characteristics of the material to flow under heat and pressure and thereby actually mold the material to the contour of the embossing plate rather than to indent or displace the composition by pressure alone. A temperature of about 230 to 300 F; in the upper platen 2l has beenfound effective for this purpose with the lower platen 28 unheated but attaining a temperature of about 150 from accumulated heat. There is no material reduction in the thickness of the web effected by the embossing plate except in the embossed or indented areas. in the press 26 for a period of about six seconds corresponding to the dwell of the presses 6 and l6 The pressure applied by the ram 29 of the press 26 is about 1450 poundsper square inch and may be varied widely depending upon the character of the embossing to be` effected. The material after leaving the embossing press is carried over the usual exchange roll and is fed from there to a curing stove in the usual manner.

In the embodiment shown, a roll 30 has been provided between the second press I6 and the embossing press 26. This may be utilized to apply a lubricant, similar to the lubricant applied by the roll I9, to the surface of the consolidated linoleum compositions to prevent any adhesion of the material to the surface of the embossing plate.

The temperatures and pressuresin the preferred procedure with the recited hypothetical conditions are summarized in the following chart: v

Temperature Pressure Pounds per Degrees square inch Fahrenheit Upper platen l Lower platen Sheet being processed. Embossing press-.

Upper platen.. Lower platen.- 150 Sheet being processed. About 210 l Accumulated heat.

The temperatures and pressures employed will vary depending upon the precise characteristics The material is held i of the binder employed. For example, mechanically oxidized linseed oil will have a different ow point than scrim oxidized oils. Such factors must be given proper consideration.

Press pads of usual `character are employed over the lower platens 8 and I8. These are not shown in the diagrammatic view. Also it has been found that a wire mesh screen such as copper screen cloth may be advantageously placed on top of the press pad for platen I8 eliminating any tendency for the material to blister due to expansion of the mix upon heating or from the building up of entrapped gases.

While I have described certain specific preferred embodiments of my invention, it will be understood that the invention is not limited to the form shown andv described but may be other- Wise embodied and practiced within the scope of the following claims.

I claim:

l. In the manufacture of molded inlaid linoleum and the like, the steps comprising rendering the upper surface of a layer of uncured inlaying composition substantially nonadhesive to a smooth pressing surface under conditions of heat and pressureiby heating said layer to a temperature suillcent to substantially reduce the plasticity of the binder thereof and by applying pressure thereto while in such condition, and thereafter applying pressure to said composition materially in excess of the initially applied pressure.

2. In the manufacture of molded inlaid linoleum and the like, the steps comprising applying heat to a layer of granulated inlaying composition to elevate the temperature thereof to a degree suflicient to substantially reduce the p'lasticity of the binder thereof and permit the composition to flow under pressure, applying pressure to the composition while at such elevated temperature, and thereafter, while the composition is at an elevated temperature but less than thel initial pressing temperature, applying pressure to lsaid composition materially in excess of the initially applied pressure.

3. In the manufacture of molded inlaid linoleum and the like from a web including a layer of granular inlaying composition applied to a burlap or similar foundation, the steps comprising applying heat and pressure simultaneously to opposite faces of said web for a time sufficient to substantially reduce the plasticity of the binder thereof and permit flow of the composition under pressure, removing the applied pressure, permitting the temperature of the composition' to fall below the initial pressing temperature but above the temperature at which the binder is plastic and will now under pressure, applying further pressure to said web materially in excess of the initial pressure, and thereafter curing the composition.

4. In the manufacture of molded inlaid linole- `um and the like from a web including a layer of granular inlaying composition applied to a bur- `lap or similar foundation, the steps comprising simultaneously applying heat and pressure to said web under such conditions of heat and pressure that the binder of inlaying composition will be substantially reduced'in plasticity and the inlay ing composition will not adhere to the pressing surface and thereafter applying further pressure to said web in an amount materially greater than the initially applied pressure andv which would, under normal conditions, result in adherence of the surface of the inlaying', composition to the pressing surface, the initial heat and pressure treatment rendering the surface of said inlaying composition substantially rfnadhesive under the inlaying composition applied to a burlap or simi-i lar foundation, the steps comprising first pressing said web between/heated pressing surfaces at relatively low pressure and relatively high temperature to reduce the plasticity of th binder of the inlaying composition and cause the mix to flow under such relatively low pressure and second, pressing said previously heated and compressed web between heated pressing surfaces at relatively higher pressure and relatively lower temperature.

6. In the manufacture of inlaid linoleum and the like from a web including a layer of granular inlaying composition applied to a burlap or similar foundation, the steps comprising simultaneously applying heat and pressure to the web with an unctuous surface in engagement with the upper surface of the inlaying composition to elevate the temperature of the inlaying composition to a degree where the plasticity of the binder is reduced and the mix is capable of flowing under the applied pressure without any material offsetting of the composition onto the pressing surface, permitting the temperature of said treated web to fall slightly below the pressing temperature and thereafter applying pressure to said web materially in excess of the initially applied pressure and at said reduced temperature to reduce the web to substantially iinal thickness and density.

7. In the manufacture of molded inlaid linoleum and the like from a web including an uncured layer of granular inlaying composition having a thermally sensitive binder applied to a burlap or similar foundation, the steps comprising consolidating said layer by pressure, elevating the temperature of said uncured layer while under such applied pressure to a point where its thermally sensitive binder is substantially reduced in plasticity and readily moldable under the applied pressure, permitting the temperature to fall, and thereafter molding the composition to conform to a pressing surface while heating said composition to a degree less than\the initial heating temperature.

8. In the manufacture of inlaid linoleum and the like from a web including a layer of granular inlaying composition applied to a burlap or similar foundation, the steps comprising i-lrst pressing said web between heated pressing surfaces at relatively low pressure and relatively high teml perature to substantially reduce the plasticity of thebinder of said inlaying composition and cause the same flow under pressure, and second, pressing said previously heated and compressed web between heated pressing surfaces at relatively higher pressure and relatively lower temperature to reduce the same to substantially nal thickness, and third, pressing said web to emboss a portion of the surface thereof, said third step being accomplished while the composition is elevated in temperature to a degree suiiicient to permit the material to flow readily under the applied pressure.

9. In the manufacture of molded inlaid linoleum and the like from a web including an uncured layer of granular inlaying composition having an oxidized oil and resin binder applied to a burlap tor similar foundation, the steps comprising subiecting said layer to pressure between heated pressing surfaces `until said layer attains a temcomposition to orient themselves under the applied pressure, releasing the pressure, reducing the temperature to a degree where pressure may be applied to the surface of the inlaying composition without adherence to the pressing surface, and thereafter subjecting lsaid layer to further pressure suflicient to consolidate the composition to substantially final density, the temperature of the composition during such pressing `being in the neighborhood of 230 F.

l0. In the manufacture of molded inlaid linoleum and the like, the steps comprising applying heat to a layer of granulated inlaying composition disposed under pressure between a pair of pressing surfaces, with the upper surface of the composition in engagement with an oiled pa er, t3 substantially reduce th'e plasticity of the bi d.- er of the inlaying composition and permit rtlhe composition to fic-w under'the applied pressure, without substantial offsetting of the composition onto the pressing surface releasing the pressure, removing the oiled paper from the surface, reducing the temperature of the surface of the inlaying composition, and applying a lesser degree c-f heat than the initial heat to said layer while disposed between pressing surfaces applying pressure materially in excess of the initially applied pressure.

ll. In the manufacture of molded 4inlaid linoleum and the like, the steps comprising applying heat to a layer of granulated inlaying compositon to elevate the temperature thereof to about 280 F., a degree sufficient to substantially reduce the plasticity of the binder thereof and perr-it the composition to flow under'pressure, applying pressure in the order of pounds per square inch to the composition while at such elevated temperature, and thereafter, while the composition is at an elevated temperature of about 230 F. but less than the initial pressing temperature, applying pressure to such composition materially in excess of the initially applied prelssure, in the order of 1450 pounds per square inc l2. In the manufacture of molded inlaid linoleum and the like, the steps comprising applying heat to a layer of i granulated inlaying composition to elevate the temperature thereof to such a degree that the plasticity of the binder is reduced and the mix is capable of flowing under conditions of minimum pressure, applying pressure to the composition while at such elevated temperature, such pressure being in an amount insufficient to causek any material offsetting of the composition onto the pressing surface, said steps being effective for reducing the thermoadhesiveness of the composition to such extent that it will not adhere to a pressing surface under conditions of extremely high pressure upon reduction of the temperature of the composition, reducing the temperature of the composition, and thereafter subjecting the same to pressure materially in excess of the initially applied presn sure.

lJOHN L. BERGER.

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