2241,3257“ Patented Dec. 31, 1946 I UNITED MATES PATENT ' I ' . ‘ POLYVINYL_ ALCOHOL 2,413,570’COMPOSITION ' ‘I . ' "Y ‘ CharlesiJifKrister, Wilmington, Del., and Henry ’ J. Sedusky and George‘ Li'Thompson; ‘Cleve land,",‘0hio,-' assignors to ' E. I.‘ du‘ Pont de - Nemours &‘Company, Wilmington, Dell., a cor ‘ _ _ pora'tion of Delaware No Drawing. Applicaticin'JunelSI 1943, Serial N0. 491,394 ,. f'zfcleinis. ., (01. 260-32) through ‘a medium of a dried-down pe1yvmy1 al cohol-reactive clay ?lm, and by the water-‘resist This invention relates .to compositions com prising polyvinyl alcohol and a clay cooperative ant‘ structures so' produced. therewith and to processes and articles employ ing such compositions as'adhe'si'v'es, and is" more - ' The processes and compositions of this inven particularlydirected to adhesive and’ ?lml-fo'r'm- 5 ‘tion are applicable in any use where two or more ing compositionscompri'sing polyvinyl alcohol objectsare to be adhesively joined; The compo and .a clay of the type of 'Chicora'No._3, to meth- 'sitions are particularly well-suited for use in‘ the ads for producingwater-resistant joined strucjlam'inat'ed board industry, fOr instance, in- the tures comprising aldhesively/unitin'g two’fo'r' more manufacture of corrugated and solid ?breboard. component parts with polyvinyl’ alcohollreactive 10 The compositionshave physical properties ideal clay compositions, and to the, water-resistant ly suited'for. use in modern corrugated board or structures so producedf solid fibreboard pasting machines, the adhesive " ' . g ._ _j. ~~ " ' It has alread'ybeen proposed ' to ' use solutions of polyvinyl alcohol for v‘ various adhesivepur- ‘ setting up more rapidly than theadhesives here tof'ore customarily used on such machines; The poses. vI~Iovvever,for many‘purposes 'polyvinyl'al- 15 laminated ?breboard produced is unusually wa cohol alone setsmuch' toojslowlyto be of_any"im_ ter-resistant, meeting all requirements of water portant'co'mmercial‘value; Furthermorajthe ad"proofness for’such board. ' hesive ?lms from a dried-down polyvinyi‘alcohol ' ,The polyvinyl alcohol usedin a composition‘ of solution are so lacking injvwater vresistance that - ' ‘this invention suitably ‘may be prepared by hy the suitability of structures jo'inedj‘with the‘poly- -zo"d'rolyrzing a, polyvinyl acetate solution and hence vinyl alcohol adhesives,‘ is ‘severely restricted for inayj contain some residual‘ polyvinylv acetate. most purposes. variousimeth'o'ds have been proPrei'erably, the amount of suchpolyvinyl acetate posed for improving the'waterre'sistance of such ' should be relatively low. The degree of polymer acihesive films, but most'of thése‘niethod‘s require ‘ i‘za'tion of'the alcohol should be such as to give a the use of agents which arefrelatively'expensive zsyis'ooéity in the solution‘ of from about 120'0-to or heat treatments which complicate and’ ,in2200 centipoises measured at a concentration ‘of Crease the cost oi the operation, Also,‘ the addi- ' '8 to 12%,‘ viscosities in the upper portion of this tion agents ‘heretofore suggested tend‘ to' make 7 "range being particularly preferred-I ' , polyvinyl alcohol'adhesive solutions‘ un'stable and ' p ‘ The clay used in a composition of this inven to alter their physical properties‘and make them 30 tiqn's'hould be one which'is cooperative with the less desirable for use in such operations as the "polyvinyl‘alcohol t0 givea‘water-insoluble Prod manufacture of laminated ?breboard, where the ilot'when an aqueous dispersion of the clay and, physical properties of_the adhesive ‘are critical in ‘alcohol is" dried down- ,It is particularly pre the operation of the commercial, pasting ma,- , ierredv to use a clay having" physical and chemical chines used. _ , ‘ ' ‘ _ a f f , " ,. _ 35 characteristicssubstantially identical with those ' It is an object of this invention to provide poly- of a clay known as “Chicora No. 3,?’ which'is a vinyl alcohol adhesive co'm'positionsjwhich-set up rapidly after application 'as' adhesives: ,Another South Carolina Cretaceous sedimentary kaolin ‘ having the following characteristics: . ‘ object is to provide‘ polyvinyl alcohol adhesives Y. which dry down f1f0m_wa1;er dispersion resistant adhesive ?lm's. ' ' ' water_. 40; vAnotherobject .is to V ,_ v ' ‘ ' .Chemical analysis _ provide water~resistant adhesives based on poly- Particle size distribution g a rf?‘gre‘lims 1 Per cent ' Mimi‘ diameter Per cent vinyl alcohol which give ‘water-resistant adhesive - ?lms Without the useof expensive insolubiiizing agents. Another objectfi's to provide water-re- 13-31 Above 10 microns; 33312 _ " sistant structures‘ adhesively joined with adhe- ,H _ V ,d l _ The foregoing and‘related objects of this, in vention are accomplished by adhesive composi tions comprising polyvinyl alcohol anda clay co operative with the polyvinyl alcohol, particular ly of the type of Chicoraj No. 3,.by processes for producing water-resistant joined. structures in, . 0.84 sives based on polyvinyl alcohol. Other objects will appear hereinafter. _ l lljvmssrilum vxidet________ _. 0-3 ‘is 28 8:12 3:8‘ (11-25 10.5 4137 69'5 60 I‘Prcsont in ‘combined'forni, calculated as indicated. 7 To make an adhesive of-thisinvention one part by weight of polyvinyl alcohol, on the dry basis, is mixed with from about 1A? to 4 parts of clay. which two or more components are united 55 For use in theimanufacture of corrugated board 1 2,413,570 3 4 or laminated ?breboard, it is preferred to use a ?breboard, the dispersion suitably may be applied mixture of about 1 part of polyvinyl alcohol to from 1 to 3 parts of clay, a mixture of 40% poly vinyl alcohol and 60% clay being especially pre ferred. It is preferred to supply the adhesive to at the rate of about from 1 to 6 lbs. per thousand square feet of glue line. Larger amounts may be used under particular circumstances, but or dinarily will not be found necessary or desirable. Smaller amounts, while suitable under special circumstances, are ordinarily inadequate to give the trade in the form of a dry mixture of alcohol and claysince the cost of transportation of. the a bond of maximum strength. dry adhesive is materially less, there is no problem The finished adhesively—joined structures of of stability of the mixture during storage, and an adhesive solution may be made up by the user '10 this invention are characterized by their remark in any concentration adapted to hisparticular able resistance to water. A solid ?breboard made needs. It is a unique characteristic of the dry up of laminations joined with a polyvinyl alco hol-clay adhesive of this invention will withstand polyvinyl alcohol-clay mixtures of this invention prolonged soaking in water without showing ply that they are more readily dispersed in water than are the separate components. , i separation. As measured on astandard Mullen testing machine, the wet bursting strength of To make an adhesive solution from the dry mix such board is remarkably higher than with board ture of polyvinyl alcohol and clay, the mixture 7 made using polyvinyl alcohol alone'as the adhe is cooked up with water to the desired concentra tion. This may suitably be done, for instance, by vsive. slurrying the solids in cold water and heating the 20 The invention will be better understood by ref mixture to about 80° C. for 1/z to 1 hour. The erence to the following illustrative examples: adhesive may then be cooled approximately to Example 1 'room temperature before use. This example describes the application of an The concentration of solids in the adhesive so lution will depend in any particular instance on 25 adhesive of this invention to the preparation of solid ?bre boxboard. the use to which the adhesive is to be applied, One hundred ‘pounds of a dry mixture of 40% but, in general, the solids content preferably may polyvinyl alcohol and 60% Chicora No. 3 clay was be about from 10 to 25%. For use as a laminat slurried with a mechanical mixer into 360 lbs. of ing adhesive in making corrugated or solid fibre board, a solids content of about 20% is preferred 30 cold water to form a homogeneous mixture. Live steam was introduced and the temperature raised and at this concentration it is especially pre to 1'70—180° F. and maintained at that tempera- " ferred to use a polyvinyl alcohol which with the ture with stirring for 1/2 hour; About 40 lbs. of clay used gives a viscosity in the range of about steam condensed into the mixture to give a ?nal from 1200 to 2200 centipoises in the liquid ad- hesive. A polyvinyl alcohol giving a viscosity near 35 mixture containing 20% solids. After cooling to room temperature, this ad the upper end of this range is particularly effec hesive was used directly for the preparation of tive. four-ply solid ?bre boxboard on a commercial The prepared adhesive solution of this invention sealing machine. The paper used was highly is a smooth, viscous liquid with considerable tack. It is easy to handle and exhibits a remarkable .40 alum-rosin sized Kraft, 0.024—0.026" thick, 92-424 degree of stability. The material shows no de terioration over considerable periods of time. . As ‘ lbs. per thousand square feet, 64” wide. Excellent board was made from the start of the machine. There was no separation of the ‘used on modern pasting machines the mixture ply and‘ immediate bonding was evident. The shows a high tack without excessive stringiness or “webbing” effects. In this respect, the mix 4.5 machine was operating at a speed of 170-200 feet per minute and the adhesive was applied at the ture of clay and polyvinyl alcohol is superior to rate of approximately 4-6 lbs. per thousand the polyvinyl alcohol alone. i square feet of glue line. » In using a polyvinyl alcohol-reactive cla The prepared board was highly water-resistant. water dispersion as an adhesive according to this invention, the a'queousdispersion is applied as a 50 There was no ply separation upon immersion in Water after a period of several months. film to one of the surfaces to be united and the second surface is superimposed on the ?lm and Eaiample 2 held‘in place while water is removed. The man The following example illustrates the applica ner of removing water may be , any method tion of an adhesive of this invention to the pro adapted to the particular situation. For instance, duction of corrugated board. in laminated paper-board'water is instantaneously , A dry mixture of 30% polyvinyl alcohol and removed by diifusion into the paperboard mem 70% Chicora No. 3 clay is used after cooking in bers which are being joined, followed by evapora water at a solids content of about 25%. tion therefrom, the adhesive setting immediately.' In preparing the liquid adhesive 100 lbs. of dry It will be understood that various methods may adhesive is slurried with 370 lbs. of cold water be used to augment the rate of water removal, such as applying heat or suspending unswelled by means of a, mechanical stirrer. When a homo starch in the polyvinyl alcohol-clay dispersion, the geneous mixture is obtained, live steam is intro duced to raise the temperature to I'M-180° F. This temperature is ‘maintained for 1/2 hour with unswelled starch taking up a considerable amount of water upon the application of heat in the paper pasting machine. _ stirring and the adhesive cooled for use. The live _ Agents designed to promote the setting up of - ' steam will condense sui?cient water into the mix ture to bring the'solids content to approximately the polyvinyl alcohol-clay mixture may. be ap 25%. plied to the surfaces to be joined. For instance, The adhesive is found to have a satisfactory when using the adhesive in laminated ?breboard. the laminations may be highly sized with rosin 70 setting time for operation upon a corrugated alum size or with any other polyvinyl alcohol board machine. The adhesive is waterproof, as insolubilizing agents, of which dimethylol "urea evident from the fact that double face board and trimethylol melamine are representative. In using an aqueous polyvinylalcohol-clay dis shows no ply separation upon immersion in water after a period of over a month. The adhesive persion of this invention for producing laminated 75 prepares particularly satisfactory board when 2,418,570 4. A dry composition adapted to be dispersed used with water-resistant.’ highly alum-rosin sized paper. in water, comprising 40% by weight, on the dry Under those conditions the corru basis, of polyvinyl alcohol and 60% by weight of gated board shows considerable strength vat the a clay substantially identical with Chicora No. 3, the mixture having a viscosity, when dispersed glue line after immersion in water for several days. I . _ in Water to give a 20% solids content, of about While in theforegoing description of this in— vention certain speci?c embodiments have been shown, it will be understood that without depart from 1200 to 2200 centipoises.v ing from the scope of the invention'those skilled ' in the art may produce various adhesive compo sitions and adhesively ‘joined structures and may employ various processes using such adhesives. We claim: _ 5. An adhesive. and ?lm-forming composition, 10 comprising an aqueous solution of polyvinyl alco hol, the solution containing a clay substantially identical with Chicora No. 3 in an amount 1% ‘times the dry weight of polyvinyl alcohol, the total solids content, dueto polyvinyl alcohol and ' 1. A dry composition adapted to be dispersed ‘ q.,clay, being about 20%, andthe clay-containing in water, comprising one part by weight of poly 1.5 solution having a viscosity of about from 1200 to vinyl alcohol on the dry basis‘ and from V2 to _4 parts of a clay substantially identical with’ Chicora No. 3. 2200 centipoises. ‘ 6. A dry composition adapted'to be dispersed in water, comprising one part by weight, on the 2._An adhesive and ?lm-forming composition,‘ vdry basis, of polyvinyl alcohol and from 1/2 to 4 comprising an'aqueous solution of polyvinyl alco 20 parts of a kaolinite-type clay, the mixture hav ing a viscosity of about from 1200 to 2200 centi hol containing a clay substantially identical with poises when dispersed in water to give a 20% Chicora No. 3, the clay being present in an solids content. amount from 1/2 to 4 times the weight of the poly '7. An adhesive and ?lm-forming composition, vinyl alcohol and the total solids content, due to clay and polyvinyl alcohol, being about from 5 25, comprising an aqueous solution of polyvinyl alco to 25%. ' i - 3. A dry composition adapted to be dispersed hol containing a kaolinite-‘type clay, the, clay be ing present in an amount from V2 to 4 times the weight of the polyvinyl alcohol and the total in water, comprising one part by weight, on the solids content, due to clay and polyvinyl alcohol, dry basis, of polyvinyl alcohol and from 1/2 to 4 parts of a clay substantially identical with 30 being about from 5 to 25%. ' Chicora N0. 3, the mixture having a viscosity, when dispersed in water to give a 20% solids con tent, of about from 1200 to 2200 centipoises. CHARLES J. KRIS'I'ER. HENRY J. SEDUSKY. GEORGE L. THOMPSON.