Patented June 30, 1942 a’ ' 2,288,293

UNITED STATES- PATENT OFFIC'

MANUFACTURE OF LAMINATED , , AND THE LIKE Colin Metcalf, Wilmslow, England No Drawing. Application July 6, 1939, Serial No. 283,065. In Great Britain July 21, 1938

‘ 4.Claims. (oi. 154-40) This invention relates to the manufacture of According to the invention, a laminated paper, laminated paper, cardboard and the like wherein ‘cardboard or the like is characterised in that the a cement is used of the kind in which , bitu laminations are united by an adhesive compris men or the like form the basic element. ing an aqueous emulsion of pitch, bitumen or the It has been proposed to make laminated pa 5 like to which has been added a small quantity per or cardboard of two or more thicknesses ce of rubber in the'form of to retard migra mented together by means of latex, with or with tion of the pitch or the like into the material. out a small quantity of ( tar) , As in the old method the pitch, bitumen or the mineral oils, bitumen, gelatine, resin soaps, gum like performs two functions. Firstly, it acts as arabic etc. to increase the adhesive power of 10 an adhesive adequately to combine the sheet ma? the latex, such latex being applied so as to pro terials together and secondly, to give a moisture I vide a coherent impervious and tough membrane’ or waterproo?ng ?lm. It is important therefore of rubber between adjacent layers of the paper that such pitches or bitumens selected for use or cardboard. Such method of manufacture has possess tenacious or adhesive properties as well also been applied using crepe paper for its ?exi 15 as being resistant to water. Such products as ble and stretchable properties. In both- cases, oils, and greases could not be used in place however, it has been emphasized that a sum of bitumen as they do not ‘give the necessary ad cient quantity of the latex must be applied vto hesion, and are therefore quite unsuitable provide a coherent layer of rubber cementing to Below are given several examples of the in gether the adjacent layers of material, ‘and at 20 vention for the composition, manufacture and the same’ time to give adequate waterproo?ng use of the improved cement. ~ ‘ ' or moisture proo?ng properties. The use- of latex in such manner appreciably Example No. 1 increases the cost of manufacture of laminated - > - Parts paper or cardboard compared with the previously 25 50% petroleum pitch aqueous emulsion ______9 known method of manufacture in whichpitch 70% latex (i. e. 70% dry rubber content)_____ 1 alone was employed. The latex process, how In preparing the cement the latex, which is ever, avoids the disadvantage of such earlier proc a known commercial product and contains cer es in that under hot conditions the pitch was tain stabilisers and possibly other addedgmatter. liable to migrate through the paper and cause 30 may be added to the pitch emulsion, or vice staining of the goods whilst at the_ same time versa, which latter may be slightly'warm so long such absorption by the paper occurs at the ex as the temperature is not high enough to cause pense of the cementing together of the lamina-. ‘coagulation of the rubber. Instead of 1 part of tions. - 70% latex there could be used 2.parts of 35% The object of the present invention is to pro 35 latex or other corresponding volume proportional vide an improved laminated sheet material or to the dry rubber content thereof. The only dif the like which is cheap to produce and which I ference resulting would be the slightly higher wa whilst employing pitch, bitumen or the like such ter content of the cement when the less concen as asphalt, tailings, etc. as the basic ele trated latex is used. ment of the adhesive and water-proo?ng medium 40 avoids the disadvantage of migration, as above Obviously theconcentration of the pitch emul sion could be varied in the same way. described. ' This invention is based upon 'a- discovery that It is to be observed that the cement, when the addition of a small quantity of rubber in made according to the formula above given and 45 when it has lost its water content by absorption the form of latex to an emulsion of pitch, bitu or evaporation, gives a deposit of which about men or the like produces an excellent cement _ for use in the manufacture of laminated paper 131/2% is rubber and 861/2% is petroleum pitch. or for like purposes, which may be applied ~or In using the above cement for the manufac used in small and economical quantities yet sum ture of two-ply laminated kraft paper a small cient to enable the pitch, bitumen or like con 50 quantity is applied to the face of both sheets stituent to cement the laminations securely to by means of back ?lling rollers and doctor knives. gether whilst providing a waterproo?ng property,‘ The two sheets are then brought together and the rubber apparently operating to retard or sub go through rollers providinga tight nip, which stantially prevent migration of the pitch or the rollers may be heated or cold. The cement was like into the paper or other absorbent material. 55 applied in quantity su?icient to provide on dry 2 ing, ‘a deposit of about 22 grs. per square'metre be varied according to the nature of the paper having about 3 grs. dry rubber content. and the result desired. Different kinds of paper will obviously require di?erent quantities of, ce Example No.2 ment, for example, a crepe paper will require . “ - Parts more than the kraft. Very little experiment will 50% aqueous emulsion elastic cottonseed be required to ascertain a suitable quantity for pitch any particular kind of paper orjcardboard. The ' 60% latex __-- 1 main feature of the invention is that whereas This mixture was" applied successfully to sev when using only pitch it is almost impossible to eral different qualities of light weight plain pa 10' prevent migration into paper or other absorbent pers by coating both webs by passing them over material, the addition of only a small quantity the top of back-?lling rollers revolving in the of latex checks such migration ‘and ensures _ liquor. The two sheets were joined together at maintained cohesion of the parts as well as pre a pair of tight nips which were heated to about ~ venting the risk of staining by the pitch. _ 75° C, It is estimated that the united coatings 15 It has also been observed that by‘ preventing on drying provided a deposit of about 20 to 25 this migration a considerably less' quantity of grs./sq. metre. pitch is required. to do the bending compared with the old method by which it was always Example No. 3 necessary to provide ‘an excess to allow for mi Parts ' 60% aqueous emulsion brown wax tailings gration. A more supple and ?exible material is (M. P. 120° F.) ______5 thus obtained. 60% latex ' 1 Whilst, in the ?rst example above described, a dry rubber content of about 14% provides a suit- ' This was applied as in Example No. 2 and is able proportion for the purpose described, such particularly suitable where a black adhesive is 25 proportion may for some purposes be reduced or undesirable. The estimated deposit on drying increased to say- 20% or 25% but. beyond that was about 20 to 25 grs. per square metre. proportion no advantage is obtained as regards Example N0. 4 I the feature of preventing migration. Where the Parts danger of migration is lower owing'either to the 60% aqueous emulsion of wool pitch. ______4 30 less porous character of the paper or other ma 50% aqueous emulsion ofbitumen ______4 terial on which the cement is to be used, or less ' 60% latex ______'_. 1 severe temperature conditions are to be expected or where a less ?uid pitch or bitumen is selected, This was used to combine successfully either two the percentage of rubber may be reduced with kraft or two crepe papers, and was ap 35 out material detriment to the required proper plied in both cases as described in Example No. ties and at the same time reducing the cost of 2. The estimated deposit'on drying was about manufacture of the cement. 25 grms. per square metre for kraft, and 30 grs. In dealing .with crepe papers, one of the prob per square metre for crepe. lems is to apply the adhesive, especially if of Example N0. 5 ~ 40 a thick viscous or pasty nature, without stretch . Parts ing or otherwise impairing the .ci-epe nature of 60% aqueous emulsion oi‘ bitumen ______6 the paper, and furthermore, after having applied China clay ' _ 1' the adhesive there is still the problem of uniting 35% latex 2 the webs using su?icient pressure to e?ect union Two crepe papers were combined with this 45 and cohesion without similarly damaging the mixture by coating one web only and subse crepe quality of the paper._ The property of the quently passing the two sheets through two pairs improved cement herein is such that it can be of light nips. The estimated deposit on drying used as a thin liquid sprayed onto the paper, was about 35 grs. per square metre. small‘ quantities only being required, both results 50 arising from the small migration or penetra Example No. 6 tion into the paper so as to provide and main . ’ - Parts tain ‘the cement as an adhesive between the'webs 50% aqueous emulsion of stearine pitch_-__ 6 of paper. 50% latex 1 _ In addition to the stabilizer or stabilizers which ' This again was used on‘ two crepe papers, but 55 may be present in the latex, the cement may con the material was on this occasion sprayed onto tain vother added matter such as emulsi?ers or I both webs. The two sheets subsequently passing . ?llers but only .in relatively small quantities so through three sets of light nips which were cold. as not to impair the adhesive and other proper? The estimated deposit on drying was about 20 ties of the bitumen, pitch or the like. to'30 grs. per. square metre. ‘ 60 The expressions “latex” or “rubber in the form of latex” are used generically to include not only - Example N0. 7 natural latex, whether in normal concentration ‘A crepe web was combined to Hessian by ap or concentrated or otherwise-suitably prepared. plying the mixture given in Example No. 5 to the but also arti?cial or synthetic emulsions or aque paper by means of the roller method of appli 65 ous dispersions of rubber or rubber-like material, cation, while the Hessian was sprayed with the whether compounded ‘or not. _mixture given in Example No. 6. The estimated Asphalt is well known for'coating roads, in deposit on drying was about 40 to 50 grs. per sulation of concrete, impregnation and the like square metre. ,- - and. mixtures oflatex, or the like, and asphalt The cements above described may be applied 70 emulsions in various proportions are well known, in other quantities and .by other suitable means and it has been proposed, by adopting a concen than stated in the above examples. Applica tration for both the latex and the bitumen emul _ tion by spraying is particularly suitable for treat sion of not less than 40%, to prevent separation ing crepe or like delicate'paper, and the quan of the constituents, the mixture, with suitable tity and pressure used in uniting the sheets will 75 added material, being usable for coating roads or 2,288,293 3 ?oors, for waterproo?ng or for pressing into solid to one side of a sheet oi said material by pressing .' forms. Such uses of asphalt or mixtures of latex the viscous mass onto the same while maintain and aqueous emulsions of asphalt have obviously ing an elevated temperature of the pressing. no association with the problem of the migration ‘means, and pressing a plurality of such sheets of the bitumen in laminated paper or the like. together to cause the same to'adhere. Mixtures of latex and emulsions'of waxy sub ;3. A methodof manufacture of a laminated stances have been used for making composite product of paper, cardboard and the like which sheets of ?brous materials, adhesion being ob comprises providinga liquid cementitious com tained by heating to above, the melting point of _ - position consisting essentially of an aqueous the wax. 10 emulsion of ‘a substance taken from the class What I claim is: , consisting of pitch and bitumen having incor 1. A method of manufacture of a laminated porated therein a sufficient amount of rubber in product of paper, cardboard and the like which the form of latex to check migration of said sub comprises providing a liquid cementitious'com stance through the individual layers of said prod position consisting essentially of an aqueous 15 uct but insufficient to impair the adhesiveness emulsion of a substance taken from the class‘ ' of said substance, said amount being between consisting of pitch and bitumen having incor about 10% and‘ 25% based on the dried deposit of porated therein a su?icient amount of rubber in the whole cementitious composition, the amount the form of latex to check migration of said sub of water in the composition being such that the stance through the individual layers of said 20 same adheres to.a sheet without any substantial product but insumcient'to impair the adhesive amount of penetration, the latex containing from ness of said substance, said amount being he - 35%—_70% of rubber, applying said composition to =‘ tween about 10% and 25% based on the dried de one side of a sheet of said material by pressing posit of the whole cementitious composition, the the viscous mass onto the same, the amount of amount-of water in the composition being such 25 composition applied being from about ,20 to 50 ' that the same adheres to a-sheet without any grams per square meter of surface'on a dry basis, substantial amount of penetration, the latex con - and pressing a plurality of such sheets together taining from 35%—'I0%_ of rubber, applying said to cause the same to adhere.\ . composition 'to one-side of a sheet of said ma- I 4, A method of manufacture of a laminated terial by pressing the viscous mass bnto the same, 30 product of paper, cardboard and the like which and pressing a plurality of such sheets together ‘ - comprises providing a liquid cementitious com- ' to cause the same to adhere. . _ position consisting essentially of an aqueous 2. A method of manufacture of a laminated emulsion of a substance taken from the class productvof paper, cardboard and the like which consisting of pitch and bitumen having incor comprises providing a liquid cementitious com 35 porated therein a su?icient amount of rubber in position consisting essentially of an aqueous _ the form of latex to check migration of said sub emulsion of a substance taken from the class stance through the individual layers of said prod consisting of pitch‘ and bitumen having incor uct but insu?icient to impair the adhesiveness of porated therein a su?icient amount of rubber in said substance, said amount'being between about the form of latex to check migration of said sub 40 10% and 25% based on the dried deposit oi’ the stance through the individual layers of saidJprod whole cementitious composition, the amount of not but insumcient to impair the adhesiveness of water in the composition being suchv that the said substance, said amount being between about ' same adheres to a sheet without any substantial -10%' and 25%‘based on the dried deposit of the amountlor penetration, applying said composition whole cementitious composition, the amount of 45' to one side ofa sheet of said material by pressing water in the composition being such that the the viscous mass onto the same, and, pressing a same adheres to a sheet without any substantial plurality of such sheets together'to cause the amount of penetration, the latex containing from same to adhere. _ . v 35%-'I0% of rubber, applying said composition COLIN METCALF.