US2430386A - Printed and coated fibrous material - Google Patents

Description

Nov. 4, 1947. J. B. BUTLER 2,430,386

PRINTED AND COATED FIBROUS MATERIAL Filed Ju1y424, 1944 2 sheetsgsheet 1 O 16 ,Y 2 if n /LH n n @L 20- 'Nov.4, 1947. 1B. BUTLER 2,430,386

PRINTED AND COATED FIBROUS MATERIAL Filed AJuly 24, 1944 '2 Sheets-Sheet 2 fx 1s" T12/U @Mop Patented Nov. 4, 1947 PRINTED AND COATED FIBROUS MATERIAL James Bayley Butler, Dublin, Eire Application July 24, 1944, Serial No. 546,354 In Eire September 9, 1943 7 Claims. (Cl. 117-15) The present invention relates to the treatment of maps and other documents such as paper and articles capable of impregnation and comprises a method of coating, and articles produced thereby. It has been the subject of a Provisional application led in the Patent Oice of the Irish Free State on the 9th day of September, 1943, No. 233/43, and officially accepted the 1st day of October, 1943.

The main object of the invention is to provide for the treatment of maps or the like in such a way that whilst the tooth of the map surface, to take pencil, ink, crayon, chalk and like markings which may be readily repeatedly removed and replaced by others with ease, is preserved, yet at the same time the surface is rendered sufficiently water resistant or fire resistant or both water resistant and lire resistant by a simple process with inexpensive, relatively easily available materials which will usually merising solution consists of the following inpenetrate below the surface and impregnate the material treated. Low cost and simplicity of process and plant are important characteristics of the invention.

The invention in brief consists in a method of waterproofing fibrous material comprising the steps of wetting the material with a polymerising solution sufficiently to impregnate the libres thereof, limiting the amount of solution applied to substantially that absorbed by the libres of the material and a thin coating around the individual fibres and leaving substantially all the natural prominences of the material projecting from the plane of the material substantially the same distance as they did prior to the application of the solution, and polymerising the solution in situ which method the polymerizing solution consists of the following ingredients in approximately the following relative proportions by weight, namely, vinyl acetate six parts; toluene sometimes referred to as toluole two parts; and methyl alcohol sometimes commercially known as methylated spirits twentyeight parts.

The invention also consists in a method of treating brous material comprising the steps of applying a polymerising solution of such character that itcan be absorbed by libres, stopping the application of solution at that 'point where the solution is being absorbed so gredients in approximately the following relative proportions by weight, namely, vinyl acetate six parts; toluene two parts, and methyl alcohol twenty-eight parts.

The invention also consists in a method of treating fibrous sheet material comprising the steps of printing intelligible markings on a face thereof, running the printed sheet of material through a bath of a polymerising solution at a rate-which removes the material from the bath at such a point in the absorption of the solution by the fibres that the continued absorption by the fibres after removal substantially saturates the fibres and absorbs substantially all surface solution leaving a thin coating surrounding the individual outer fibres, polymerising the solution, and calendering the material in which method the polymerising solution consists of the following ingredients in approximately the following relative proportions |by weight,

namely, vinyl acetate six parts; toluene two parts,

and methyl alcohol twenty-eight parts.

The invention `further consists in an article of manufacture made by any of the methods according to any of the preceding ve paragraphs which article comprises a sheet of fibrous material having a matte or toothed surface with a map printed therein, the fibres of said material having a coating of a polymerised synthetic resin therearound, an interlocking matrix of said polymerised resin holding the inner libres or said material, the prominences forming the matte surface of said material projecting substantially the same distance above the depressions thereof as they ydo in untreated material of the same character whereby said material is made waterproof and fire resistant and said surface has tooth and will readily receive pencil, ink, chalk and crayon markings which may be readily removed and rewritten and said surface retains its continuity after repeated folding and creasing the aforesaid polymerised synthetic resin being prepared from the following ingredients in approximately the relative proportions by Weight stated, namely, vinyl acetate six parts; toluene two parts; and methyl alcohol twenty-eight parts.

The invention also consists in methods ol treating fibrous materials substantially as herein described and in brous materials treated by methods substantially as herein described.

Referring to the accompanying diagrammatic drawings which illustrate apparatus suitable for carrying my method into effect, and articles which may be thus produced by such a method:

Figures 1 to 4 illustrate a form of hand type apparatus for treating maps in one way according to the process of the present invention in which- Figure l is a plan from the top,

Figure 2 a side elevation looking in the direction of the arrows 2-2 of Figure 1,

Figure 3 is an elevation, and

Figure 4 a detail of the chain guide.

Figures 5, 6 and '7 relate to maps which Amay be or are treated according to the present invention in which- Figure 5 is a diagrammatic representation .of a map of any kind,

Figure 6 isa plan on a greatly enlarged scale of typical or conventional bresforming thesurface of a map or paper sheet in plan, and

Figure '7 a typical or conventional more highly enlarged surface in elevation of a rough type vof sheet for purposes of illustration, the bres being shown surrounded by protective resins as indicated below.

Referring to the drawings Va base member or framing I is provided with a trough k2 adjacent one end which is preferably lined with zinc as at 3 and may satisfactorily be constructed with dimensions of 4" in diameter by four feet in length 'which is somewhat less than the width of base member I. Copper should not be used since it will inhibit the poly'merisation of the treating material. It is preferred to use -a one-,half inch diameter steel roller E disposed in the trough 2 in a resilient manner as conventionally illustrated by a spring 5 `in Figure 3. Treating vsolution 6 4composed as described below -is placed in trough 2 in sufcient amount to cover roller Il.

An apron I extends along in front of trough 2 and slopes gently toward `it so that the feeding of material to be treated is facilitated and any splash or drops `of solution 6 drain back into `trough 2.

Along the opposite side or :rear of trough Y2 v.is a large drip or drain board 8 extending upwardly at an angle of about degrees and covered with plate glass 9. If desired 32 ounce sheet glass may be used instead of plate glass. Board 8 is supported by suitable uprights at II). .Directly above base member I, trough 2, and drain board 8 is a drying arrangement comprising a chain guide and support I I provided with a channel I2 formed by Vupstanding walls I3 and I4 in which rides a 1A roller chain I5. Chain guides and supports Vare provided on both sides of the machine as shown in Figure 1 and the same applies to chains `are carried along therewith. Depending from eachof the rods I6 is a pair of clips I8 for hold- Ving treated material in drying and draining position.

4Chains I5 pass around and engage idler sprockets I rotatably mounted on shaft 20. Chains I5 likewise pass around and engage sprockets 2i which are keyed to shaft 22. A crank 23 attached to shaft 22 permits the moving of the rods along supports II as needed.

The operation of the device is as follows: A map or sheet to be treated is inserted singly under roller Il and quickly pulled through the solution 6. The roller 4 insures that the map is completely covered with the solution. The resiliency of the mounting will relieve any undue strain on the map and insure that there is no abrading of the printed surface.

. After the treatment ithe-map or o ther article is hung from clips I8. Crank 23 -is rotated to move rods I6 and their associated maps along supports :I-I. Excess material may drip on glass 9 and run back into trough 2.

The composition for use, for instance, in the above apparatus for purposes of the present invention comprises one or more of the substances selected from the group consisting of vinyl acetate, vinyl chloride and chloroprene. Of these vinyl acetate is preferred, A suitable formula using vinyl acetate is .as follows:

Parts by weight Vinyl acetate s 6 Toluol 2 Methylated spirit 28 Total, making l% 36 The methylated spirit may conveniently be in the form 0f industrial methylated spirits. It may be replaced by other solvents or diluents, forexample ethyl alcohol- When compounding the composition it is preferred to crush the vinyl acetate to almost the size of coarse granulated sugar, Vplace the toluol in a container in a warm water bath at about F. and add the crushed'vinyl acetate a little at a time, stirring continuously. 'It is desirable to keep the mixture agitated while the acetate is Ygoing into solution so as to avoid the formation of a dense sticky vmass at the bottom of the container, which vwill not readily dissolve. The spirit is then added while stirring. The bath temperature is not critical but :the toluol is volatile and it is desirable to keep loss by .evaporation at a minimum. The composition can also rbe mixed cold and the methylated spirit may be added to the toluol prior to the addition of the acetate if desired. This method will, however, take longer and requires more agitation,

Where the mixing is done overnight a closed flask or container should be employed to minimize evaporation, If left luncovered the solvents will evaporate and the composition becomes thick and will require additional solvent. If placed in a closed container it will keep for months. A ten pound batch requires about an hour to compound.

While the proportion of 16% vbyweightof vinyl acetate is not critical it is believed optimum. That is as the percentage of acetate is increased above 16% the iinish of the treated article becomes smoother and the matte characteristics which give it "tooth and the ability to receive pencil, crayon or ink marks decreases until the iinish becomes glossy in character and the ability to receive writing as above disappears almost completely. As the composition becomes thicker with the increase in percentage of acetate the drying time is slower and the impregnation less thorough, Not only is more .material used, but the thickness retards and decreases polymerisation with a resultant less satisfactory product.

On the other hand as thepercentage of acetate is `decreased below 16%, there is a concomitant falling off in the waterproof and fire-proofing characteristics of the composition.

Vinyl acetate has been found to give the most satisfactory results. It is very susceptible to catalytic and anti-catalytic effects. In addition to the catalysts mentioned above the per-salts such as the perborates and percarbonates as well as benzoyl peroxide, hydrochloric acid, aldehydes, halides such as zinc and tin chlorides, ultra violet light and Water aid in polymerisation. 1n general oxygen and peroxides are catalysts and antioxidants act as inhibitors.

Although no theory is advanced as essential to the present invention it would appear that vinyl acetate with a molecule of Water H2O, on polymerisation vinyl acetate forms a chain of units somewhat as follows:

The above is a partial structural diagram of a theoretical chain of units of polymer of vinyl acetate. The chain may contain an undened number of vinyl acetate units. The product compounded as above is of low viscosity so that it effects substantially complete impregnation of any paper or article with a thin coating'around the fibres. When in such thin coating the aforesaid chain building or polymerisation accelerates and the cohesion of adjacent 4molecules and their bonding into large ones takes place rapidly. This action is described as spontaneous as contrasted with more highly viscous solutions which may coat rather than impregnate. Polymerisation is expedited by heat, light, oxygen, peroxides and other catalytic agents. Where cardboard or the thicker and densermaterials are to be treated the action of infra red rays may be used to advantage.

As regards the solvent some solvents particularly favour the polymerisation of vinyl acetate. They include ethyl alcohol in all strengths from absolute to 50% strength benzene, toluene, acetene, ethyl acetate and butyl acetate.

In the above composition toluol (toluene or methyl-benzene) is employed as a solvent which will readily take the acetate into solution. Where 84% toluol is used the treated product takes longer to dry. In addition it is at present a material which is not easily obtainable. Commercial toluol may be used and its viscosity is not critical.

The addition of ethyl alcohol or methylated spirit increases the impregnating qualities of the composition, improves the matte character oi the surface, and greatly decreases the drying time. Industrial methylated spirit is preferred since the commercial grade usually contains naphtha. Naphtha forms an opalescent solution which does not readily dissolve 'the vinyl acetate. Other solvents such as ethyl and other low alcohols, carbon tetrachloride, acetone, trichlorethylene, butyl acetate, ethyl acetate, chloroform, hydrocarbons and otherI organic solvents may be employed if desired depending upon solubility, speed of vaporisation, inlammability, toxicity, availability and cost.

The general result of treating a paper sheet typified by the reference 2d of Figure 5 on which is printed a map such as the conventional design indicated by 25 of Figure 5 is illustrated diagrammatically with reference to Figures 6 and 7 which are intended to indicate respectively the appearance in plan and elevation of a paper surface in which fibres 26 are surrounded by a composition 21 as referred to above. It must be borne in mind that spaces 28 between the fibres are also assumed to be covered by the composition. The tooth of the original material is not materially changed by the composition as indicated by reference to Figure 7, the heights of the fibres above the general level of the base being substantially unaltered.

General Where reference is made to acetate the stated equivalents may be substituted.

Although it has been said the optimum concentration for vinyl acetate is usually about 16% adjustment may be made to suit the type of paper and finish required. The deposit must not be too thick or the proper tooth eiect may be lost.

Although in applying the process the paper is generally submerged in the treating liquid this does not mean that the tooth of the paper is ultimately submerged in varnish. What apparently happens is that the film of the composition is so thin that when dry and set it does not fill up the valleys between the minute natural projecting fibres on the surface of the paper. The natural tooth is' therefore preserved. Ordinary varnish completely covers this tooth up and the bres are then submerged below the varnish. in other words the contour of a cross section of the paper when magnified remains substantially unchanged before and after treatment. The Whole map may be, and generally is, completely submerged below the surface of the liquid composition when treating it in the bath or trough. This is a totally different submergence from that of the bres or tooth The surface is waterproofed by penetration of the liquid and any writing or the like can be wiped oil with a rag. The composition will not provide a tooth" on a paper which has no tooth before treatment.

Toluene, as explained, may be replaced by an equivalent percentage of spirit, this substance helping in the solution of the vinyl acetate or the like but with` spirit it is desirable that heat and agitation should be employed but the invention is not limited to these solvents or diluents.

From many aspects ordinary methylated spirit is the most satisfactory solvent or diluent.

The invention may be applied to documents and articles of all kinds. The term document is to be interpreted as including such things as maps, deeds, drawings, cheques, sheets, labels, cards, or the like with or without the addition of matter placed thereon by printing, typing, colouring, Writing or the like, such documents being made of paper, card, pasteboard, cotton, linen or other brous flexible material. The term articles is to be interpreted as including such things as bags, cartons, containers, wrappers, moulded articles and the like of cellulose, bre, paper, paper pulp, pasteboard, cardboard, or the like with or without the addition of matter placed thereon by printing, typing, colouring, writing, or the like.

Instead of immersing the documents in a bath they may be sprayed with the solution or the soiution may be applied with a brush or the like, in either of which cases the documents will be impregnated with the solution. After the solution has dried the resin becomes polymerized in situ in the interior and on the surface oi the paper thus giving a complete waterproof quality to the document.

Tests carried out on maps treated by the methods according to the invention show that no shrinkage or expansion takes place, there being consequently no alteration to the scale of the map. They can be immersed in water without harm and mud, grease, and even hot materials, such as meat, gravy and fat, when poured upon the maps have no effect whatever and can be washed off with soap and water without injury to the maps. Further, the maps may be folded and crumpled without in any way injuring them.

Although the invention has been described as applied to maps it can equally well be applied to la-bels used for botanical purposes and any of the things which are included in the term document hereinbefore mentioned. When applied to labels and other things thicker than paper these should be dried to remove the absorbed moisture. The time of immersion may vary from a few minutes to half an hour according to the thickness and nature of the material treated.

Drawings or patterns made with colour, charcoal, soft pencil, or the like are fixed by treatment with my improved method.

Cheques or legal documents written with writing ink or indiev ink are also xed by my improved method so that, should a subsequent addition be made on the surface by forgery or otherwise, application of a chemical ink remover, such as a solution of sulphurous acid, will within a few seconds remove the subsequent ink additions, but the original writing will not be affected except on exposure for a considerably longer period to the action of the chemical ink remover.

Surfaces prepared in accordance with the present invention can be written upon in ink or pencil or can be painted with watercolours. Such subsequent additions can be removed, when desired, by chemical or other suitable removers leaving the original document intact.

The invention thus provides means whereby the fraudulent alteration of documents may be readily detected. Papers and documents have been heretofore treated for the purpose of waterproofing and obtaining a surface which would readily receive pencil, ink, chalk, or crayon markings. However, previous treatments have not been satisfactory in that they require a number of steps, yield coatings which are brittle, crack easily or are not capable of repeated use. Varnishes and the like may check or flake off and the article is soon unfit for use. Where a roughening agent such as pumice is used re-use or alteration of the written matter is greatly inhibited and an additional step is required which greatly slows down quantity production and increases the cost. No mere coating will offer an at all satisfactory solution to the problem. All previous attempts at a solution which have been found decrease the flexibility of the treated article to a considerable degree at least insofar as the retention of surface continuity is concerned. The present invention achieves the desired result and avoids the objections mentioned above.

The impregnating substance used according to the present invention can readily be caused to impregnate the paper or other fibrous material treated, surrounding the fibres and in some cases penetrating them.

The treatment of articles has heretofore in many cases resulted in streaks and other unevenness which causes considerable loss inthe rejection of articles which would otherwise be-regarded as prime. While this harmful effect may be caused in part by the character of the solution or composition used it is likewise dependent upon the manner of application. A clear even surface is best obtained by relating the speed of the feed of the material to be treated to the density thereof. The heavier the material the slower the speed. At optimum application speed there is some absorption by the inner fibres after the material leaves the bath. This has the effect of thinningthe layer of impregnant, improving the speed, evenness and extent of polymerisation. Where the material is soaked in the solution spotting may occur, yielding an inferior surface. The importance of proper relation of speed to material in quantity production is even more evident when it is realised that obtaining an even surface requires that the treatment be confined to a single application. In continuous machines the proper adjustment of speed should eliminate drip and beading of the edges. Heat, light, air, peroxides and the like have a catalytic action, aiding the polymerising of the composition.

Accordingly hot or warm air may be beneficially employed to speed the drying action, especially with thick layers. very likely because with thin layers catalytic agents are more effective in that they can reach all parts of the composition more nearly at the same time. Where cardboard or the thicker and denser materials are to be treated the action of infra red rays can be utilised to advantage. The amo-unt of acetate or equivalent in the solution may be reduced to 12% or 10%, decreasing its viscosity and enabling it to penetrate more easily thick denser materials. As stated above the article composed of a plurality'of fibres after treatment appears to be covered by the polymerised acetate or equivalent and the inner fibres held in an interlocking matrix. The matte surfacel having tooth results from small projections and depressions. The maintaining of tooth is believed to flow from at least two causes. One, the retention of the original tooth of the paper, the small surface projections of which have not been submerged, and, two, small pits or holes caused by variable evaporation of the solvents from the applied composition.

When the paper is properly treated very little of the composition remains upon the surface. In the rst few uses it has been found that the ability of the surface to receive pencil, ink, chalk and crayon markings increases in some cases. This would appear to flow from the slight abrading action or erasure which brings into greater prominence any original tooth of the paper. Best results are believed to be obtained when the original tooth and the effects of the composition are combined, but either alone is believed to give a satisfactory result, save that the entire or substantial submergence as explained below of the prominences in the paper surface should be avoided.

To the very strong adherence between the composition and the libres is added the strength of the matrix formed by the large polymers which interlink in a tangled mass. As polymerisation proceeds the material hardens and the action becomes substantially irreversible so that even the application of the original solvents will not substantially alter the material. A very strong interlocking of bres is obtained and substances that would normally be capable of wetting the fibres are excludedmaking thev treated article waterproof. In addition the re Vresistance of most fibres is increased by the treatment.

In addition to the above action there is the formation of a matte surface which has tooth by which is meant a surface easy to Vwrite upon with pencil, ink, chalk, or crayon. Y, The Writing can be quickly removed with soap and water or a damp or treated rag or sponge or other suitable agent after which the surface may be written on with the same facility as before without any damage thereto. This procedure may be repeated on the same surface a great number of times resulting in a substantial saving as where expensive maps or the like are used and with great convenience and saving of time as when maps must be mounted in a certain way on `special equipment or there happens to be only one available.

As explained, the paper to be treated may comprise drawings, maps, deeds, labels, sheets for wrapping or the like with or without the addition of matter placed thereon by printing, typing, colouring, writing, or the like, such documents being .made of paper, card, cardboard, pasteboard, corrugated board, cotton, linen, or other fibrous flexible material. Articles may be taken to comprise bags, cartons, corrugated boxes and the like of cellulose, libre, paper, paper pulp, pasteboard, cardboard or the like with or without the addition of matter placed thereon Vby printing, typing, colouring, writing or the like.

Sulphur inhibits polymerisation. The presence of 1% of sulphur under certain conditions will completely inhibit the polymerisation of vinyl acetate. Sulphur and copper compounds are harmful in this regard.

A brief rsum of the process applied to maps is as follows:

A map or the like which is to be treated is passed through a bath of the solution, is then drained and hung up to dry. For most paper a thorough wetting with the solution is all that is required, there being no need for soaking. Where cardboard or the like is to be treated it has been found desirable to dry it before treatment as by hanging in a dry heated room, ironing, or passing between heated calendering rolls. A solution having or 12% acetate is then used depending on the density of the 4material to be treated. The denser the material the lower must be the percentage of acetate or the equivalent. Where a large amount of very heavy work is to be done pressure equipment may be utilised to insure thorough impregnation.

rfhe bath container may be constructed as a long trough having a roller .the `whole length thereof and journalled in bearings at each end. The rollers should be in the liquid so that the map or the like is kept below the surface during treatment and is thoroughly wetted as it is drawn through the bath.

This may be done fairly rapidly. The maps or the like may then be hung from a suitable drying rack.

An attempt to coat the map a second time will cause streaking. The same is true of too thick a solution. When the sheets are hung up to dry an excess of solution may be found to collect on the lower edge where it will form a thick glossy layer unless wiped away with a sponge or cloth saturated with ethyl alcohol or a mixture of 10% toluol and 90% ethyl alcohol.

Where calendering or ironing the treated material is employed this must be effected not to defeat the object of the invention in retaining tooth Similarly, any pressure on the paper during coating or at any other time must similarly be suitably chosen; Writing on surfaces prepared as describedherein may be removed either by a. dry cloth or a cloth moistened with water or an oily rag in accordance with the type of crayon or the like employed to make the marking.

I claim: 1

1. A method of waterproofing vfibrous material comprising the steps of wetting the material with a polymerising solution sufficiently to impregnate the fibres thereof, limiting the amount of solution applied to substantially that absorbed by the fibres of the material .and ar thin coating around the individual libres and leaving substantially all the natural prominencesA of the material projecting from the plane of the material substantially the same distance as they did prior to the application of the solution, and polymerising the solution in situ in which method the polymerising solution consists of the following ingredients in approximately the following relative proportions by weight, namely, vinyl acetate six parts; toluene two parts, and methyl alcohol twenty-eight parts.

2. A method of treating fibrous material comprising the steps of applying a polymerising solution of such character that it can be absorbed by fibres, stopping the application of solution at that point where the solution is being absorbed so that substantially al1 surface solution is absorbed and a very thin coating surrounds the outer surface fibre with substantially all the natural prominences of the material projecting and polymerising the solution in which method the polymerising solution consists of the following ingredients in approximately the following relative proportions by weight, namely, vinyl acetate six parts; toluene two parts, and methyl alcohol twenty-eight parts.

3. A method of treating fibrous sheet material comprising the steps of printing intelligible markings on a face thereof, running the printed sheet of material through a bath of a polymerising solution at a rate which removes the material from the bath at such a point in the absorption of the solution by the fibres that the continued absorption by the fibres after removal substantially saturates the fibres and absorbs substantially all surface solution leaving a thin coating surrounding the individual outer libres, polymerising the solution, and calendering the material in which method the polymerising solution consists of the following ingredients in approximately the following relative proportions by weight, namely, vinyl acetate six parts; toluene two parts, and methyl alcohol twenty-eight parts.

4. An article of manufacture which comprises a sheet of fibrous material having a matte or toothed surface with a map printed thereon, the fibres of said material having a coating of a polymerised synthetic resin therearound, an interlocking matrix of said polymerised resin holding the inner fibres of said material, the prominences forming the matte surface of said material projecting substantially the same distance above the depressions thereof as they do in untreated material of the same character whereby said material is made waterproof and fire resistant and said surface has tooth and will readily receive pencil, ink, chalk, and crayon markings which may be readily removed and rewritten and said surface retains its continuity after repeated folding and creasing the aforesaid polymerised synthetic resin being prepared from the following l1 ingredients in approximately the relative proportions by Weight stated, namely, vinyl acetate six parts; toluene two parts; and methyl alcohol twenty-eight parts. A 5. An article of manufacture made by the method of claim l.,

6.. An article of manufacture made by the method o f claim 2'-.

7; An article of manufacture made by the method of claim 3.

' JAMES BAYLEY BUTLER.

REFERENCES CITED The following references are of record in the me of this patent:

Number l2l UNITED 'STATES ,PTENTS vName Date Nicholls Oct. 19, 1926 Coleman Dec. 26, 1939 Winkel-mann July 4, 1939 Hinman. Aug. 26, 1941 AllB1, May 20, 1941 Hibbert Jan. 28, 1936

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