US 2668124 A
Description (OCR text may contain errors)
Feb. 2, H J, MALLABAR MANUFACTURE OF DECORATIVE LAMINAE Filed Oct. 51, 1951 COATING COMPOSITION FIG-2 DECORATION APPLIED BY PRINTING OPERATION W0 Q Q40 FIG -5 DRIER LAMINATING BACKING MATERIAL INVENTOR HERBERT J.-MALLABAR BY w w/zjkwl ATTORNEYS THERMOSETTING RESIN SOLUTION culties.
Patented Feb. 2, 1954 MANUFACTURE OF DECORATIVE LAMINAE Herbert J. Mallabar, Watford, England, assignor to Oxford Corporation, Dayton, Ohio, a corporation of Ohio Application October 31, 1951, Serial No. 254,175
6 Claims. (01.117-) This invention relates to improvements in the manufacture of decorativelaminae of the type in which a face sheet of paper bearing a desired self coloring or an ornamental design,
such as for instance a wood grain pattern or any v pattern that can be etched preferably by intaglio, is secured to a backing consisting either of further paper sheets, of wood or plywood or of materials such as plasterboard, fibreboard, asbestos sheet or the like rigid sheeting material.
-Hitherto the production of tinted or colored paper for use as surface or print sheets in such decorative laminae has presented certain diffi- In the first-place, it is not convenient for a paper manufacturer to make less than two tons of a particular shade of paper, whereas, by way of example, only ten hundredweights ofany particular shade may be required. The inclusion of a colored pigment, coloring matter, or light reflecting material inthe paper pulp necessitates stopping the machine at the conclusion of the operation, thoroughly washing out the machine in order to get rid of the coloredfibres and running the machine for some little timeafter it has been restarted until the correct thickness of paper has been restored. In the second place, the addition of such coloring matter to paper pulp has presented great difficulty with regard to matching the tint. As a means ofovercoming this diflioulty it has been proposed'to tint a white paper base but this has proved a'failure asit has not been possible to keep the sameshade in sheet in the production of decorative laminaecomprises applying a layer of white or colored pigmented filler or light reflecting material to a web of paper, smoothing the coated surface such as by brushing to ensure uniform distribution of filler and then impregnating the Web of paper with a thermosetting resin. e
()ther objects and advantages .of the invention will be apparent from the following description, the accompanying drawings, and the appended claims. r
2 In the drawings 1 Fig. 1 is a diagrammatic view showing apparatus suitable for practicing the coating operation in accordance with the invention; 1
Fig. 2 is a diagrammatic view showing apparatus suitable for practicing the decorating operationin accordance with the invention; and
Fig. 3 is a diagrammatic view showing'apparatus suitable for. practicing the impregnating operation in accordance with the invention.v
The present invention is a continuation-inpart of application Serial No. 94,972, filed May 24, 1949, now abandoned. 1.. Referring to the drawings which illustrate diagrammatically the operations followed in carrying out the invention, Fig. -1 indicates the coating operation which is performed in connection with the coating of the web of paper. The supply of paper is indicated at ID and may be in the form of a rollsuch as received from the paper mill, and'of suitable characteristics as to weight, size, surface, and. other characteristicssuch as relatively good wet strength and absorptivecapacity. The paper web may be eitherfilled or may be substantially free of filler, the filler-if such is used being preferably white Orneutral in color so .that it will not require special treatment in the subsequent coating operation in order to compensate for such initial color. r
The paper isunwound from the roll andtravels as a web I I to an application zone which may be formedrby means of an endless felt I2 passing over guide rolls l3, l4, with a transfer roll 15 running in a bath it of the desired coating composition- Roll I4 guides the felt into contact with the web I I while the latter passes around a large cylinder or drum 2U, suitable driving being [provided for the several rolls in the customary manner. Coating material from the bath lB is picked up on transfer roll [5, transferred to the traveling felt I2, and from it applied to the surface of the web H, the web then continuing diminishing in width progressively, with the final brush being quite narrow and 'very soft to'avoid rust which would discolor the 'delic'ate' pastel tints. The mounts for the brushes should preferably be made of aluminum or other non-rusting material, and the hairs or bristles are preferably attached or sewn thereto by means of a stainless wire. Preferably drum 20 should be made of or covered with some non-rusting material, also for the purpose of avoiding rust and discoloration. It will be evident that if desired more than one such coating may be applied to the web and smoothed and distributed thereon, after which the web passes into a dryerindicated at 25 where it is converted into a normally :dr-ied web.
The coating composition which is applied in the bath I6 is selected to have the desired color characteristics for the particular type of decorative laminae to be produced. The composition consists essentially of a filler or pigment of the desired color to impart either the whiteness or the particular shade or tint required in the finished sheet, together with adhesives and such other materials as may be desirable in obtainingthe proper flowability of the composition and the proper retentionthereof upon the coated sheet. The application of the pigmented filler as a coating with the resulting concentration thereof primarily on thesurface is advantageous chrome yellow, chrome green, cadmium yellow,
ochras and umbras, cobalt, and other metallic 'oxides, such materials being. selected and incorporated in the proper quantities and in suitable admixture w-ith the white fillers .to produce the desired shade or color. Dyes may also be employed to impart or aifect the color provided they are not incompatible with the resins subsequently applied.
In addition to, or replacing the pigmented materials .in whole or in part, the invention also provides for incorporating light reflecting particles in the coating, including metallic powders such as bronze or aluminum, scale materials such as fish scale and H scale (a form of pearl essence), micas, and the like. Such light reflecting materials may be supplied to the coating composition and applied in the manner described to develop desired surface characteristics in the final product.
The term coloring material is used herein in the sense of applying to all such fillers, pigments, dyes and light reflecting particles, etc.
It will be evident that difierent coatingcompositions may be prepared in as small quantities as desired, and with considerable accuracy and precision so that the-change from one colored pigment to another, and the matching of differ-- ent runs of the same colored pigment, may beaccomplished quite readily and accurately. It is only necessary to change the relatively small quantity of coating composition which remains -'in the bath Hiand :on the transfer rolls and felt, the washing out of one color and the replacement thereof by another being performed easily and quickly. Thus, any desired number of different'zcolored runs of the coated paper maybe produced, and in as large or small amounts as desired, from the some stock supply of paper and great flexibility as well as uniformity .of
colored surface isthus obtained.
Following its. drying in oven 25 the coated sheet of paper is rewound and the rewound roll 30 is then in condition to receive decoration. This is accomplished by performing a printing operation, the web with the colored surface still being soft, flexible and highly receptive to printing. It is passed into a suitable printing press indicated at .31 which maybe a rotogravure type may be impregnated directly with the thermosetting resin material after which the web loses its soft, pliable and receptive character. The web 4| is passed over suitable guide rolls 42 to an immersing bath which contains the thermosetting resin solution. The web travels through the bath and is maintained therein for a suincient length of time to accomplish substantially complete impregnation with the resin solution. The impregnating material contained in bath 43 is a solution of a thermosetting resin, suitable examples of which are phenol 'i'ormaldehyde, urea formaldehyde, and the melamine resins. Such resins are usually obtainable in dry powdered form and are converted into solution by dissolving the same in a solvent such as alcohol and water in suitable proportions. A solution of such resinous "material for application in accordance with the present invention may contain a solids content of approximately LE-5%. I
The selection of the particular resin depends to some extent upon the color desired, the use of phenol formaldehyde resin which has a light brown color being unsatisfactory where the finished surface is to "be a light pastel shade, such resin however being quite suitable'for use in producing a laminated sheet such as a walnut reproduction. When white or pastel shades or bright colors are desired it is found more desirable to use the urea formaldehyde and the melamine resins. It is also found that it is not necessary that the paper as originally produced have a filler incorporated therein during its manufacture as would normally be considered necessary in order to overcome the tendency for the unfilled sheet to be rendered translucent owing to the impregnation with urea formaldehyde and melamine type resins. Such translucent condition does not ordinarily occur with respect to a sheet which is impregnated with the phenol formaldehyde resin, but even with the other resins, the necessary opacity to overcome translucency maybe satisfactorily provided by the incorporation of the filler in the coating operation above described.
Following impregnation the web is removed and travels over guide rolls -44 to a drying oven 45 in which it is suitably dried to a moisture content of approximately 5%, and at a temperature below that which will produce reaction in the 'thermosetting resin, 2; suitable temperature being of the order o'f60 C. Suitable'lengths thereof may be assembled with backing material comprising one or more sheets of paper, wood, or plywood, or material such as plaster-board,
:fibreboard, asbestos sheet or entirely rigid sheet material, the backing: sheets themselves being impregnated with .a thermosetting resin. Such resin however need not be the same as that blanc fixe with continuous stirring.
used in the preparation of the decorative surface sheet as described above. The surface sheet is bonded to one or more of the backing sheets by the application of heat and pressure in a laminating operation indicated diagrammatically at 46. For example the assembled sheets may be pressed between platens in a hydraulic press at a pressure of the order of 800-1000 lbs. per square inch and at a temperature of 120 C. for minutes, thereafter being allowed to cool while the pressure is maintained. In order to achieve a polished surface it is desirable to use mirrorpolished stainless sheets as cauls, the surface finish being a reproduction of the finish on the cauls. An insoluble, infusible sheet having the properly colored and decorated surface is thus produced.
In addition to the high-pressure laminating process described above, the resin-impregnated web may also be used in conjunction with the lowpressure laminating process employing suitable pressure rollers in place of the press used for the high-pressure process. In the case of the low-pressure system, the resin varnished web need not be cut into suitable lengths as is the rule when the plain colored or decorated sheets are laminated in a press, but the web may be used in the form of a continuous process by bonding the web to suitable backing materials by feeding through pressure rollers. low-pressure system, the paper web can be bonded to such soft base materials as Gypsum board, etc.
Three examples of typical coating compositions follow:
Example 1 6 kilos of blanc fixe (barium sulphate) con taining -30% water, i. e. in the paste form as normally supplied to manufacturers of photographic paper, is placed in a mixing vessel and 1 gallon of water added thereto. When the paste is dissolved the necessary dye is added. The dyes are the same as used for tinting the raw paper base and must be fast to urea. The dye is dissolved in approximately 50 c. c. of alcohol before being added very slowly to the blanc fixe solution. Approximately '70 c. c. of pure glycerine well mixed in an equal quantity of alcohol is then added to the blanc fixe solution whilst the latter is being well stirred. The solution is stirred for about 15 minutes. It is found convenient to add both the solution of the dye and the glycerine to the piano fixe solution through a glass funnel at the end of which is a glass jet attached to the funnel by a piece of rubber tubing. The jet is made by heating a glass tub-e in a Bunsen flame and then drawing out the tube to provide a narrow throat from which the tube can be severed after making a file out.
Melted gelatine, prepared by soaking 650 grams of gelatine in 8 gallons of cold water for between 24-36 hours after which time the water is drained off and the gelatine dissolved in an earthenware vessel which is placed in boiling water, is then added to the blanc fixe solution containing both dye and glycerine and the whole then placed in the hot water bath and stirred well for another 15 minutes. The gelatine must be skin gelatine or best quality skin glue. To the said solution is then added 120 c. c. of a 1 in 15 solution of pure chrome alum. The chrome alum is used as a hardening agent for the gelatine. As with the solution of the dye and glycerine, the chrome alum solution must also be added slowly to the The glass Using the jet and funnel is utilised for this purpose. When the chrome alum has been thoroughly mixed with the blanc fixe the resultant solution is set aside in a cool room over night.
The next day the composition is placed in a hot water bath and re-melted and thereafter a further grams of gelatine, dissolved in 1000 c. c. of water, is added thereto together with a further 100 c. c. of the chrome alum solution through the aforesaid jet.
To the resultant coating composition and for every 5 gallons thereof, 40 c. c. of milk are next added. The milk is used as an anti-froth and spreading agent and it should have been allowed to stand for some hours and then skimmed carefully before being used.
After thorough mixing, the coating solution is filtered through a very fine gauze sieve, so fine that the composition will only pass through the sieve by working it through with a good size paint brush.
Whilst the weight of coating must vary to some extent with the precise nature of the paper to which it is applied and with the purpose for which the paper is to be used, generally speaking the application of a coating of 12 grams per square metre is likely to prove satisfactory.
During the manufacture of the said coating composition a temperature of approximately 45 C. should be maintained.
During the actual machine coating a, temperature of approximately 40 C. should be maintained if possible.
Example 2 25 lbs. of aluminium paste are dispersed in 50 gallons of solvent. 24 gallons of this mixture are then added to 11 gallons of pigmented filler to produce a coating composition which is ready for brush coating on to a web of paper.
Emample 3 78 lbs. of H scale (Pearl essence) are added to gallons of thinner. 14 gallons of this mixture are then mixed with 1 gallon of pigmented filler and then the whole well mixed and. then brush coated on to a web of paper.
The success of the process of the invention hereinbefore described is thought to reside in the fact that an aqueous non-film-fonning coating composition of a relatively special nature is applied to the web of paper by specific mechanical means. When the 'said mechanical means and the requisite coating composition and the procedure for applying the coating composition to the web of paper are operated in unison, then there is provided a technique for producing certain end effects which have never been achieved before. The principal objectives obtained may be summarised as follows:
1. Treatment of the paper by a mechanical means plus a special coating composition applied in a specific way facilitates the production of decorative high pressure laminates.
2. The high pressure paper treated in accordance with the invention permits the proper saturation of the laminating materials, the efficiency of such saturation not being materially reduced by the treatment.
3. The invention provides means of introducing colours and other materials which permit the reflection, diffraction and refraction of light in the basic colours. Such effects cannot be combined in the paper beater in which pulp for the .high pressure laminates was originally made.
4. The combination of mechanical means and novel coating compositions has the added advantage that the flexibility of the paper is not impaired, thus permitting the decoration to be done in continuous rolls and i e-rolled. When the paper is being re-rolled it is not only flexible but there is no material that will. cause the fibres of the paper to stick together and mar the surface to which decoration has ultimately to be applied.
The essential ingredients displayed by a coating composition as detailed in Example 1 above may be enumerated as follows:
1. An adhesive binder material which will not interfere with penetration but will still allow the design to be printedan example being hide glue.
2. A colour material of which there is a wide selection including dyes and pigments.
3. One or more solvents of which there are any numberexamples being water and alcohol.
4. An anti-foaming agent-an example of which is'skimmed milk.
5. A preservative of which there is a wide selection-an example being phenol.
In a coating composition of this type an antifoaming agent is essential in order to ensure that the coating composition will work properly with the mechanical means described.
Generally speaking the components of the coating composition must in all cases be of such a nature that they will not greatly reduce the absorption quality of the paper, or leave a surface of such a. nature that is unsuitable after receiving a decoration. It is a fact that the nature of high pressure laminating papers necessarily makes them of a fairly coarse grain and of high absorption. The difficulty of attempting to print any type of uniform decoration upon a paper having a high degree of absorption is manifest, particularly if it is desired to apply multi-coloured designs. On the other hand high pressure laminating papers treated in accordance with the present invention may be printed satisfactorily.
Decorative laminae produced in accordance with the invention have a widespread application in industry. For example, they are particularly suitable for use in hospital wards, shipbuilding, cinemas, interiors of buildings, furniture, etc. on account of the ease of cleaning and hygienic properties.
While the process herein described constitutes preferred embodiments of the invention, it is to be understood that the invention is not limited to this precise process, and that changes may be made therein without departing from the scope of the invention which is defined in the appended claims.
What is claimed is:
l. The process of making a paper adapted for use as a sun-face print sheet in the production of decorative laminae and of obtaining predetermined color characteristics therein from a supply web consisting of a highly absorbent sheet of soft, saturable paper of uniform color characteristics which comprises the steps of applying to one side only of said web an aqueous nonfilm-forming coating composition containing an adhesive and a coloring material adapted to penetrate and remain primarily in the surface zone of said web, smoothing and spreading said applied coating composition while still workable uniformly over said surface of said sheet with a brushing action resulting in theproduction of ii a substantially uniformly coated surface of the desired c'olor upon said one side of said web leaving said coated web soft and flexible and receptive to printing, and applying a decorative surface to the coated side of said web by a printing operation and retaining high receptivity of said web for subsequent impregnation and saturation by a thermo-setting resin suitable for laminating said sheet to backing sheets to form a decorative surface thereon.
2. The process of making a decorative laminated product incorporating a. surface print sheet of Paper and of obtaining predetermined color characteristics in said sheet from a supply web consisting of a highly absorbent sheet of soft, saturable paper of uniform and neutral color characteristics which comprises the steps of applying to one side only of said web an aqueous non-film-forming coating composition containing an adhesive and a coloring material and forming a uniform coated surface of the desired color on said one side of said web by a brushing action leaving the opposite side substantially untreated and the treated surface of said web still absorbent and suitable to receive printing, drying said coated web to form a. web which is soft and flexible and suitable for receiving surface decoration, applying a surface decoration to said coated web surface by a printing operation, said web retaining high receptivity for subsequent resin impregnation, and thereafter impregnating and saturating said coated Web with an unpigmerited thermosetting resin capable of effecting lamination of said surface sheet with backing sheets to form a decorative surface thereon.
3. The process of making a decorative laminated product incorporating a surface print sheet for overlying a backing which contains a thermosetting resin comprising the steps of applying to one side only of a supply web of soft, saturable paper of uniform substantially neutral characteristics as to color and highly absorptive properties for resin solution an aqueous non-film-formlng coating composition containing an adhessive and coloring material of predetermined selected color imparting properties in the form of a, relatively thick suspension with resulting concentration of said coloring material primarily on the surface of the sheet leaving the opposite side of said sheet substantially untreated, brushing said coated surface of said sheet to smooth and distribute said applied coating uniformly over the surface of said sheet, drying said coated web leaving said coated web surface soft and flexible and receptive to printing, decorating said coated web surface by a printing operation leaving said web still receptive to resin impregnation, and thereafter treating said web with a termosetting resin composition to substantially completely impregnate and saturate said web for subsequent lamination with said resin containing backing.
4. The process of making a decorative laminated product incorporating a surface print sheet for overlying a backing which contains a thermosetting resin comprising the steps of applying to a supply web of soft, saturable paper of uniform substantially neutral characteristics as to color and highly absorptive properties for resin solution an aqueous non-film-forming coating composition containing an adhesive and coloring pigment of predetermined selected color imparting properties in the form of a relatively thick suspension with resulting concentration of said pigmented coating material primarily on the surface of the sheet, brushing said coated surface of said sheet to smooth and distribute said applied coating pigment uniformly over the surface of said sheet, drying said coated web providing a smooth surfaced soft, flexible and relatively yieldable sheet, decorating said coated surface of said web with a pattern leaving said web still adequately receptive to subsequent impregnation by a solution of thermosetting resin for efiecting lamination with said backing, and thereafter impregnating and saturating said web with a laminating resin adapted to be thermally set.
5. A process as defined inclaim 1 in which said supply web of paper as produced is substantially free of filler, and an opacity-imparting filler is incorporated in said coating composition and present upon the coated surface of said sheet to overcome the tendency of the impregnated sheet to become translucent.
10 6. The process as defined in claim 4 in which the brushing is effected through an alternating hard and soft brushing action.
HERBERT J. MALLABAR.
References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,508,720 Perry Sept. 16, 1924 1,825,877 Loetscher Oct. 6, 1931 1,997,358 Cochrane Apr. 9, 1935 2,069,648 Denner Feb. 2, 1937 2,084,081 Faber June 15, 1937 2,292,118 Guhl Aug. 4, 1942