US1957369A - Paper manufacture - Google Patents

Description

y 1, 1934- J. H. SWAN, an 1,957,369

PAPER MANUFACTURE Filed Aug. 30, 1929 -2 Sheets-Sheet 1 ay 1, 1934. J. H. SWAN, 3D

PAPER MANUFACTURE Filed Aug. 30, 1929 2 Sheets-Sheet 2 mm 3 G ah w V b m t Illlll'Illllll 5J1 Patented. May 1, 1934 I UNITED STATES 1,957,369 PAPER MANUFACTURE Joseph H. Swan, 36, Middletown, Ohio, assignor to The Gardner-Richardson Company, Middletown, Ohio, a corporation of Ohio Application August 30,

13 Claims.

- This invention relates to the manufacture of paper, and particularly to the manufacture of board adapted for use in the making of containers and the like. One ofthe principal objects of this invention is to provide a paper or board which is grease proof and moisture proof, is suificiently flexible.

and elastic to permit bending, is substantially odorless and tasteless, stands up well in use and does not objectionably deteriorate upon standing for considerable intervals of time, and is commercially economical.

Another object of the invention is to provide a method of forming such a'grease proof paper or board, which is simple, economical and highly effective, and which permits the continuous application of a composite coating with the formation of a product of good character.

Still another object of the invention is to provide apparatus for carrying out the above method.

Another object of the invention is to provide a superior coating composition adapted for use in the manufacture of the above board product.

Other objects and advantages of the invention will be apparent from the following description, the accompanying drawings, and appended claims. In the drawings in which like characters of reference designate like parts. throughout the several views thereof,-.

\ Fig. 1 is a partial diagrammatic side elevational view of apparatus constructed for carrying out the method of this invention;

Fig. 2 is a view similar to Fig. 1 disclosing another portion of the apparatus;

Fig. 3 is a plan view of the apparatus shown in Fig. 1,, certain parts being broken away and in section to illustrate the construction thereof;

Fig. 4 is a vertical sectional view taken on the plane of the line 4- 4. of Fig. 2; 4

Fig. 5 is a vertical sectional'yiew of a modified form of apparatus for applying the final wax coating;

Fig. 6 is a plan view of the apparatus of Fig. 5 'with the coating roll removed; 'and Fig. '7 isa vertical sectional view' on an enlarged scale through a piece of container board .made in accordance with this invention.

This invention is particularly applicable to the rendering of paper or board, such as container board, impervious to grease so thatcontainers made therefrom may be used for packaging greasy or oily substances which would otherwise 55 penetrate through the package. When such a 1929, Serial No. 389,425

product is used for packaging foodstuffs, such as peanut butter or the like, it is particularly desirable that the surface of the container board be substantially tasteless and odorless. The coating should be of such character as to form an im- 6 pervious layer on the surface of the board without pin holes which destroy the effectiveness of the coating, and it should be sufficiently flexible and elastic to permit bending of the board, such as is necessary in the formation of the box orcontainer, without cracking. The coating should also be of a durable nature and one that will stand up well in use and will n'otobjectionably deteriorate upon standing for considerable intervals of time. In accordance with the present 7 invention, a coated paper product is formed which is unusually efficacious in satisfying the .above requirements.

Referring to th' drawings which disclose a preferred embodiment of apparatus constructed in accordance with this invention, a roll of paper to be coated is indicated at 10 carried by a suitable reel which is journalled at 11 upon aframework 12. The paper to be coated" passes in a travelling web indicated at 13 over suitable guide rolls 14 and 15 and thence into contact with the upper surface of roll 16'of a coating press. This press comprises also a lower roll 1'7 dipping within a trough 18 to which the coating solution is supplied in any suitable manner. Rolls 16'and 1'7 are positively driven and are mounted in adjustable bearings so that they can be vertically adjusted relatively to each other to regulate v the pressure-at the nip of the rolls as desired. -In operation, rotation of lower roll 17 within the coating solution serves to pick up a film of the coating material upon the surface'of the roll.

A portion of this film is transferred tosthe surface of the upper roll 16, the amount or thickness of the film being regulated by adjusting the pressure of contact of the rolls 16'and 17, and this film is then transferred to the travelling web 13. Q v

The coating composition applied at this point comprises essentially rubber latex and casein. The rubber latex is a relatively concentrated water solution of the pure sap of the rubber tree in colloidal state. The addition of an oil insoluble adhesive, such as casein, to the rubber latex imparts superior characteristics of adhesiveness and grease proofness. Rubber latex has qualities of elasticity and spreading ability and enables a relatively thin coating to be used with satisfactory covering power; it also functions very satisfactorily to lay any fuz'z which may be protruding from the surface of the paper and covers up irregularities-of the surface. It is also 'a good moisture proofing and water proofing .88ent.*\

used for this purpose. An alkaline compound, such as sodium carbonate, ammonia, sodium hy-.

droxide, etc., is preferably added to preserve the alkalinity of the coating, this being found to assist in preventing deterioration of the coating on standing with increase in the effective life of the coating.

A preservative, such as formaldehyde, paraformaldehyde or borax, is preferably added to the coating. found to .preserve the coating from bacterial action and to act as a reduoing agent to prevent objectionable oxidation or=other deterioration of the coating. It also improves .the' quality of the coating, a very durable and resistant tough coating being produced, which is more grease proof and more water insoluble. A formaldehyde such as paraformaldehyde, which is a solid at ordinary temperatures and can be conveniently handled, is found to be highly satisfactory for this purpose, and remains stable in the coating after drying, also adding water proof qualities thereto. The addition of a polysulphide, such as sodium or ammomum polysulphlde, to this coating is found solids and in addition about 2% y Weight of an to improve the covering power thereof, and prevents deterioration and the formation of pin holes in the coating. The polysulphide may be conveniently prepared by first generating a. relatively concentrated water solution of sodium or ammonium sulphide, and then adding a. quantity of sulphur to the solution and dissolving the where casein is used, a solution is first prepared by adding commercial powdered casein to water in the proportion of about one pound to the gallon. This mixture is allowed to soak for a period of time such as about an hour, with the addition of 'a quantityof an alkaline compound such asammonia, sodium carbonate, sodium hydroxide, tri-sodium phosphate, or the like. For example, about one pint of ammonia added to ten gallons of the casein solution gives very satisfactory results. The addition of the alkaline compound 'facflitates solution, and the solution may also be heated somewhat to assist in the dissolving action. To this solution is added a preservative, such as. 'paraformaldehyde, which assists in preventing deterioration of the coating, The paraformaldehyde is first made up into solution in a considerable quantity of water. Thus satisfactory results have been secured where the paraformaldehyde has been added to ten times its own weight of water, or even in higher dilution. Satisfactory proportions of the formal- 3 cial operation. when substantially more than 2%"or the formaldehyde is used, the solution thereof is' added in small amounts to the casein solution which is agitated or flowing freely in .a stream, this serving to prevent undesirable thickening of the casein.

The rubber latex is added in emulsion form. Preferably a rather concentrated latex emulsion isused, very satisfactory results being secured with an emulsion containing 38% solids in water, and also containing asmall amount, about 2%, of an alkali such as amomnia or sodium carbonate to preserve the alkalinity of the emul- 8 sion. To the rubber latex emulsion is added the polysulfide solution prepared as above described, satisfactory results being secured by the use of about2% by weight of polysulphide on the total solids of the emulsion. The casein solution containing the formaldehyde is then added to the latex emulsion, preferably with agitation. Various proportions of these ingredients may be used, depending upon the particular product or use of the product desired. Satisfactory results have been secured with compositions containing from 15% to 90% by volume of latex, the balance being primarily an alkaline solution of casein containing formaldehyde. Where the coating is used for a lower or base coat, it .is

found preferable to provide in excess of 50% rubber latex by volume in order togive a base coating which has high flexibility and high covering alkali metal polysulphide and 2% by weight of analkaline compound such as ammonia, is mixed with a casein solution containing about one poundof casein to the gallon of water, and also containing about 10% of paraformaldehyde on the dry weight of the casein, in the proportions of about 60% or more by volume of rubber latex and 40% or less by volume of casein solution to form the liquid coating composition.

The web 13 with the coating applied to the under surface thereof at the coating press 16-17 then passes with the coated surface in contact with smoothing and spreading rolls indicated at 20, 21 and 22 respectively. These rollsv are positioned adjacent the coating press so as to contact with the coating just shortly after its application. Satisfactory results are secured where the first smoothing roll is positioned an effective distance of about six inches from the contactof the paper with the coating roll, the remaining smoothing rolls following in close succession, being spaced about six inches apart. A smoothing roll made of cold rolled steel having a diametef of about three inches is satisfactory. These rolls are positively driven, preferably against the direction of movement of the paper. Using a 5 paper speed of about 50 to 150 feet per minute, goot results have been secured where the-rolls are driven against the direction of the movement of the paper at a surface speed of about 80' feet per minute. As shown clearly in Fig. 3,. 0

the smoothing and spreading rolls are arranged obliquely across the machine with reference to the. travelling web of paper. This is found-to any tendency toward streaking of the relatively sticky coating, and to facilitate the smoothing and spreading of the coating.

The coated sheet then passes with the uncoated surface in contact with guide rolls indicated at 23 and 24. To facilitate the rapid drying of the coated web, drying blasts such as coating.

hot air blasts are supplied to the coated surface of the .web. As shown a conduit 25 extends longitudinally beneath the coating machine,"this conduit 'being supplied with drying fluid, such as air, by a pump indicated diagrammatically at 26, the pump forcing air under pressure across suitable heating coils 27. Adjacent the smoothing and spreading rolls are upstanding. ducts 28, which serve to direct blasts of the heated air against the travelling web so as' to dry the coating sufficiently to permit another coating to be applied with only a short travel of the web. These ducts discharge the heated air against the. web opposite the supporting guide rolls 23 and 24, this arrangement serving to permit the proper ten-.

sioning of the web and serving to support and hold the web adjacent the discharge of the ducts to secure more satisfactory drying while minimizing danger of breakage.

' Each of the ducts 28 is constructed as shown more particularly in Fig. 4. The conduit 25 is provided with a rectangular opening 29 over which is mounted a respective duct, the end walls of which diverge as indicated at 30 so that an upper outlet opening 31 is provided which extends across the full width of the web. The openings 29 in the respective ducts progressively increase in cross section from the duct closest to the pump and thence throughout the series to the end of the conduit to thereby equalize the distribution of air discharged from the respective ducts. Each duct is also provided with a throttle valve 32 journalled at 33 in the end walls of the duct. Each valve 32 may be separately controlled by a suitable lever 34, or the levers may be interconnected by suitable linkage for simultaneous actuation.

' In accordance with the present invention, a

composite grease proofing coating is provided on the surface of the paper or board, which composite coating is made up of upper and'lower coats having different characteristics and which are found to combine to give a superior resultant "The web 13 with the base coating treated as above described, then passes with the "coated surfacein contact with the upper surface of rotatable roll 35 of a second coating press. This coating press is constructed similarly to v the first coating press, and has a lower rotatable;

roll 36 dipping within a trough 37 containing the coating material, whereby a film of coating of the desired thickness is transferred from the lower.

roll toithe upper roll and thence to the previously coated surface of the travellin web 13. J

The upper layer of the composite grease proofing coating at this point comprises essentiallya mixture of an oil insoluble adhesive such as- I casein, a polyhydric alcohol such as glycerine,

and a preservative such as paraformaldehyde. The casein has high grease proofing qualities, and also.assists in securely binding the coating to the sheet. The addition .of glycerine to the casein imparts characteristics of resiliency to',the upper coating, and tends to prevent cracking thereof when the board is bent in the formation of the container without impairing the grease proofing character thereof, also improving the spreading and covering power of this top coating.

' Other. pgl'yhydric alcohols, for example glycols such as ethylene glycol, 'can-be-used with satisfactory resultsin substantially thesame manner as glycerine. Other oil insoluble adhesives such as alkali metal silicates, glues or gelatine, can be used in place of casein. a v i In the preparation of the coating composition for this top coating the casein is made up into a solution in the manner and in the proportions as described above for the baseqcoating, a preservative such as paraformaldehyd being added to the casein solution in the manner previously described. Glycerine is then added to thecasein solution, satisfactory results 'being secured by using a weightof glycerine equivalentto about one-half to one and one-half times the dry produced has superior characteristics to a coating formed by merely a plurality of coats of a particular composition. The first or basev coat provides a permanent non-deteriorating coating next to the sheet which acts as a protective coating to prevent the upper coat from sinking into the sheet. The base coat has unusual flexibility which is quite important in container board which is subjected to severe bending in the manufacture of the ultimate containers. This coating, forming a flexible background for the overcoat, serves to prevent cracking of the overcoat upon bending of the board. A high percentage of a rubber compound, such as rubber latex, in the base coat acts as a water proofing and moisture proofing agent; and the spreading or covering power of this material, which is improved by the formaldehyde, together with its flexibility enables a substantially impervious coating to be formed with only a relatively thin film. This is materially assisted by the fuzz laying qualities of the base coating. The relatively high percentage of casein givesan overcoat having high grease proofing qualities, and this grease proofing layer is properly held upon the surface by the base coat. A coating having a backing of high flexibility with a surface of high grease proofness is thus and construction to rolls 20, 21 and 22. Additional drying ducts 44 branching off of'the conduit 25 supply heated air to the coated surface of the web adjacent the spreading rolls 40, 41 and 42 and assist in drying the coating.- As many coats as desired may be applied to the travelling web 13. Thus asshown, a third coating press comprising an upper rol1 45 and a lower roll 46 dipping within a trough 47 is provided. If it is desired to apply only two grease proof coats as above described, coating solution is not supplied to the trough 4'7.

Where a coating material is used containing a substance such as casein, which is precipitated by the addition of a solution of certain metallic salts, such as salts of iron, aluminum, magnesium.

copper and the like, it is found that the coated product may be further improved by passing the sheet with the coated surface into contact with a solution of such a metallic salt to precipitate or otherwise fix the coating. This gives superior water proofing qualities to the sheet. Thus very satisfactory results may be secured by supplying 15f.-

a water solution of a metallic salt, such for example as aluminum sulfate to the trough 47, a thin film of this solution being transferred by the rolls 46 and to the coated surface of the from the discharge ends of the ducts so'that the coated side of the web does not contact with solid objects until it is substantially dried. The upper end of each of the ducts is formed with a rim or flange of smooth metal so as to provide asupporting. surface for the web when the machine is shut down or the web is being threaded through the machine.

A thin overlying film of a water insoluble wax is preferably applied over the grease proof coating in order to protect the coating from exposure and to provide a substantially odorless and tasteless outer surface. Very satisfactory results are secured with paraflin, beeswax, Montan wax, or other well kne water insoluble waxes. From the standpoint-of economy and ease of application, paraflin is preferred for this purpose. Theoverlying wax coat not only protects the under grease proof coat from deterioration, but also adds tov the water proofness or moisture proofness of the coating, which is particularly advantageous in the packaging of deliquescent substances, such' as crackers for example. I

- In accordance with the present invention, this\ top film is applied 'by capillary attraction to the web so that an extremely thin controlled film is produced with resultant economy in operation. The use of a very thin outer paraffin layer is moreover advantageous, in that it more readily permits the grease proof board to be glued such as is done by a gluing machine in gluing the flaps for the formationof; the final box. shown, a capillary coating press is provided beyond the driers for applying this top wax coat.

This coating press comprises a positively driven rotary steam heated roll 55 mounted to rotate in contact with a foraminous or felt covering 56 carried by a stationary supporting member shown as "a cylindrical tube 57. Tube 5'7 is mounted within a trough 58 so that the outer felt covering dips within coatingmaterial supplied to the trough. Steam coils 59 within the'trough serve to maintain paraflln, or other water insoluble wax supplied thereto,"in molten condition.

This wax feeds by capillary attraction through the foraminous covering to the surface of the coating roll 55, whichin turn transfers a very thin film to the coated surface of the web which is brought in contact with the upper surface of this coating roll. The coating roll 55 is heated,

, such as in the manner of a steam heated drying indicated at 55'.

drum or calender roll, so-that the thin filmof. molten paraflm supplied thereto is maintained in proper molten condition until transferredto thecoated web.

A modified form of wax applying press is shown in Fig. 5 in which the steam heated'coating roll is This roll is mounted to rotate in contact withthe curved upper surface of a wood block 60 mounted within a coating trough 58' heating cola 59'. The block 60 is provided with a plurality of thin transverse saw cuts or slits 61 through which coating material may be transferred by capihary attraction to the surface of the coating roll. If desired a foraminous or felt covering 62 may be positioned over the wood block, the ends of the covering extending down into the coating liquid.

The sheet then passes from the finalcoating press through pressure rolls 63 and 64 carried in vertically adjustable bearings by the frame 65.

coated paper then passes to a reel 67, or may be passed to suitable cutters and cut into sheets of desired size for the manufacture of containers.

If desired the paper or board previous to the coating as above described, may be first subjected to a sizing treatment. This sizing treatment is useful in that it tends to prevent curling of the paper after the coating'is applied. Thus the board, or the layer of the board forming the outer surface which receives the coating, may be a hard sized sheet, or one which has been made up from paper stock to which a suflicient ouantity of size, such as rosin orparaflin size, has been added as to materially retard the rate in which water or ink penetrates into the sheet. Very satisfactory results are secured by forming a sheet from paper stock to' which rosin 'size has been added at thebeaters in the proportion of eighty to one hundred pounds or more of size to twelve hundred pounds ofpulp. A sheet which will stand up for approximately five minutes or over in the water drop test, which means that water will not penetrate the sheet in that time, is

quite satisfactory. Or the sheet maybe given a surface sizing by an application of a size to the surface of the formed web,-using suitable conventional sizing materials such as above specifled. The surface sizingnnay be applied during the formation'of the sheet prior to the application of the grease proofing coating. The sized paper is then supplied in roll formas indicated at 10 te the coating machine and the grease proofing coating is applied to the sized sheet.

Referring to Fig. .7,, a section througha preferred sheet or board is diselosed, which is found to be highly effective for usein containers for the packaging of greasy materials, and which protects the materials from water and damp atmospheric conditions. The sheet comprises inner layers of ordinary boardv stock '70, with an intermediate layer '11 of asphalt material such as an emulsion of asphalt and clay. The outer surfaces of'the board are formed of good rade. liner stock, providing a bottom liner 72 and a top liner '73. One of the outside liners, such as the top liner '73 which is adapted to form the interior for drawing the paper through the machine. The

plete built-up sheet of container board. The board as thus formed is then passed to the coating machine where the composite grease proofing coating is applied, there being a lower or base coat of high flexibility indicated at '74 and an upper or overcoat of high grease proofing quality indicated at 15. A final overlying water insoluble wax coat '16 is then applied over the grease proofing coating. A container formed from this sheet is protected from water and moisture tending to penetrate from the outside into the interior of the container by the intermediate asphalt layer and by the base coat 74, and is made effectively grease proof, water proof and moisture proof on the interior by the coating applied to the interior surface of the container.

While the forms of invention disclosed herein constitute preferred embodiments hereof, it is to be understood that the invention is not limitedto these precise forms, 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: 1. A paper product of the character described comprising a sheet having a composite grease proof coating applied thereto, including a lower coat-ing layer comprising rubber latex, casein and a soluble preservative, and an upper coating layer comprising casein and a polyhydric alcohol, said sheet and composite coating being flexible to maintain thecontinuity of said composite coating against disruptive effects in use due to bending and the like.

2. A paper product of the character described comprising a sheet having a composite grease proof coating applied thereto, including a lower coating layer containing a rubber compound, an oil insoluble adhesive, and formaldehyde, and an upper coating layer containing an oil insoluble adhesive precipitated in situ on the surface of the sheet, said sheet and composite coating being flexible to maintain the continuity of said compositecoating against disruptive effects in use due to bending and the like.

3. A paper product of the character described comprising a sheet having a composite grease proof coating applied thereto, including a lower coating layer containing rubber latex and a polysulphide, and an u'ppercoating layer containing an oil insoluble adhesive of high grease proofing character, said sheet and composite coating being flexible to'maintain'the continuity of said coma due to bending and the like. "u

4. A paper product of the character described comprising a sheet having a composite grease proof coating applied thereto, including a lower coating layer containing arubber compound. an oil insoluble adhesive, and a polysulphide, and an upper coating layer containing an oil insolubleadhesiveand a polyhydric alcohol, said sheet and composite coating being flexible to maintain the continuity-of said composite coating against disruptive effects in use due to bending and the like.

5. A paper product of the'character described comprising a sheet having a composite grease proof coating applied thereto, including a lower coating layer containingrubber latex, an'oil insoluble adhesive,v a polysulphideand a preservative; and an upper coating layer including an oil insoluble adhesive, a polyhydric alcohol and a thereon being preservative, said sheet and composite coating being flexible to maintain the continuity of said composite coating against disruptive effects in.

alcohol, saidsheet and composite coating being .fiexible'to maintain the continuity of said composite coating against disruptive effects in' use due to bending and the. like. 7

7. A paper product of the character described comprising a sheet having. a composite grease proofing surface applied thereto, said grease proofing surface comprising a lower layer including a rubber compound, an oil insoluble adhesive and formaldehyde; and an upper layer containing an oil insoluble adhesive, a polyhydric alcohol and formaldehyde, said sheet and composite coating being flexible to maintain the continuity of said composite coating against disruptive effects in use due to bending and the like.

8. A paper product of the character described comprising a sheet having a composite grease proof coating applied thereto including a lower coating layer containing a rubber compound and having high flexibility, and an upper coating layer containing a polyhydric alcohol, formaldehyde, and an oil insoluble adhesive, said sheet and composite coating being flexible to maintain the continuity of said composite coating against disruptive effects in use due to bending and the li e.

9. A paper productof the-character described comprising. a sheet having a composite coating comprising a flexible moisture proofing layer and a grease proofing layer-superimposed thereon, the flexible layer, comprising a mixture 'of a dispersed rubber and an oil insoluble adhesive, and containing formaldehyde in substantial amount in excess. of 2% by weight based on the weight of the oil insoluble adhesive to materially improve the durability and resistance of the flexible coating, said sheet and composite layer thereon being flexible to withstand the disruptive effects during use due to bendingand the like.

10. A'paper product of the character described comprising a' sheet having a composite coating comprising a flexible moisture proofing layer and a grease proofing layer superimposed thereon, the grease proofing layer including an oil insoluble adhesive and formaldehyde in substantial amount in excess of 2% by weight based on the weight of the oil insoluble adhesive to materially improve the durability'and resistance of thefgrease proofing layer, said sheet'and composite layer flexible to withstand the disruptive eflects during use due to bending and the like.

' 11. A highly moisture proof and grease proof paper product of the character described adapted for the packaging of greasy materials, comprising a sheet having a composite grease proofing surface coating, including a lower coating layer containing rubber latex and having-high flexibility,

and an upper coating layer containing casein and having high greaseproofln'g quality, said sheet and composite coating'being flexlbleto maintain the continuity of said composite coating against disruptive efiects in use due to bending and the like.

12. A highly moisture proof and grease proof container board adapted for the packaging of greasy materials, comprising a sheet having a composite grease proofing surface coating, including a lower coating layer containing rubber latex and having high flexibility, and an upper coating layer containing casein precipitated in situ or fixed on the surface of the sheet to give high grease proofness while providing a substantially odorless and tasteless surface, said sheet and composite coating being flexible to maintain the continuity of said composite coating against disruptive effects in use due to bending and the like.

13. A paper product of the character described,

comprising a sheet having a composite grease ,boi'nprising a sheet having a composite greaseproofing coating applied thereto, including a proofing coating applied thereto, including a lower coating layer containing a rubber material having high flexibility, an upper coatinglayer containing casein and having high greaseproofness, and an overlying coating providing a substantially odorless and tasteless surface, said sheet and composite coating being flexible to maintain the continuity of said-co posite coating against disruptive effects in use ue to bending and the like.

15. A paper product of the character described,

, comprising a sheet having a composite grease proofing coating applied thereto, including a lower coating layer containing a rubber material' having high flexibility, an upper coating layer containing casein and having high greaseproofness, and an overlying coating of a water insoluble wax, said sheet and composite coating being flexible to maintain the continuity of said composite coating against disruptive effects in use due to bending and the like.

16. A paper product of the character described comprising a sheet having a composite grease proofing coating applied thereto, including a lower coating layer containing rubber latex, casein,

formaldehyde, and a polysulfld, and anupper coating layer containing cuein, a polyhydric hydric alcohol, and formaldehyde, and an overlying water proofing and moisture proofing coatalcohol, and formaldehyde, the casein of the upper coating being precipitated in situ on the surface of the sheet, said sheet and composite coating being flexible to maintain the continuity of said composite coating against disruptive effects in-use due to bending and the like.

comprising a' sheet} having a composite grease proofing coating applied thereto including a lower coating layer containing rubber latex, casein, formaldehyde, and a polysulflde, and an upper coating layer containing. casein, a polyingproviding a substantially odorless and taate-' less surface, said sheet and composite coating being flexible to maintain thecontinuitybf said composite cbating against disruptive effects in use due to bending and the like. 18. A grease proof. and water proof, pape product of the character described, comprising a hard sized sheet having a composite grease proofing surface coating applied to' the hard sized sheet maintain the continuity of said composite coat-,

ing against disruptive effects in use due to bending and the like. v

19. A grease proof and water proof paper product of the character described, comprisinga hard sized sheet having a composite grease proofing surface coating applied to the hard sized sheet andmaintained primarily on the surface thereof,

said grease proofing coating comprising a lowercoating layercontaining rubber latex having high flexibility, and an upper coating layer containing casein and having high greaseproofness,

said sheet and composite coating being flexibleto maintain the continuity of said composite coating against disruptive effects in use due to bending and the like.

not of the character, described comprising a hard sized sheet having a composite grease proofing surface coating applied to the hard sized, sheet and maintained primarily on the surface thereof, said greaseproofing coating comprising a lower coating layer containing rubber latex and having high flexibility, and an upper coating layer containing casein and having high greaseproof- I ness and an overlying water proofing and moisture proofing coat providing a substantially odorless and tasteless surface, said sheet and composite coating being flexible to maintain the con-' tinuity of said composite coating against disruptive effects in use due to bending and the like. 21. A grease proof and-water proof paper product of the character described, comprising a hard sized sheet having a high composite grease proofing surface. coating applied to the hard sized sheet and maintained primarily on the surface thereof, said grease proofing coating comprising a lower coating layer including rubber latex, an oil insoluble adhesive, and formaldehyde, and having high'flexibility, and an upper coating layer including an oil insoluble adhesive, a polyhydric alcohol, and formaldehyde, and having high greaseproofness, said sheet and composite coating being flexible to maintain the continuity of said composite coating against disruptive effects in use due to bending and the like.

22. A paper product of the character described comprising a sheet having the surface thereof greaseproof, said sheet having a greaseprooflngf surface stratum thereon consisting of superim- 17. A paper product of the characterdescribed posed layers, said layers comprising a lower layer havinghigh flexibility and forming a base coating for the reception of an upper coating, and an upper coating layer greaseproof in its characteristics superimposed on said lower layer, said sheet and composite layer thereonibeing jointly mg use 23. A paper product of the character described comprising a sheet having a composite greaseprooflng surface, said surface comprising a'lower layer which includes a substantial proportion of rubber compound and has high flexibility, and an upper layer which includes a substantial proportion of an oil insoluble, greaseproofing agent and has high ,greaseproofness said sheet and composite layer thereon being/flexible to withstand the effects of bending during use.

20. A grease proof and water proof paper prod;

flexible tojwithstand the effects of bending dur- 24. A paper product of the character described comprising a sheet having a composite grease proofing surface, said surface comprising a continuous lower layer having high flexibility and an upper coating layer of high greaseprooflng quality, said lower layer serving to lay the fuzz on the sheet to prevent said fuzz extending through the upper greaseproofing layer, and said sheet and composite layer thereon being flexible to maintain the continuity of the said composite layer against disruptive effects during use.

25. As a product of manufacture, a paper sheet having the surface thereof greaseproofed and adapted for forming into containers and the like,

said sheet comprising a grease'proofing surface tive effects of bending in use.

26. As a product of manufacture, a paper sheet having the surface thereof greaseproofed and adapted for forming into containers and the like,

said sheet comprising a greaseprbofing surface stratum consisting of superimposed layers, said layers. comprising an inner formed layer of high flexibility bonded to said sheet and including a substantial proportion of a rubber material, and an upper layer formedin superimposed relation upon said inner layer andfpf a relatively. low

I flexibility but greaseproof in its characteristics,

said layers being interbonded, whereby the high flexibility inner layer serves to maintain unbroken the characteristics of the upper layer against disruptive effects of bending in use, and an overlying top coat of a moisture proofing agent superimposed upon the aforesaid layers.

27. A greaseproof and waterproof paper product of the character described, comprising a hard sized sheet having a greaseprooflng surface stratum upon said hard sized sheet consisting of superimposed layers, said layers comprising. an inner formed layer of high flexibility bonded to said sheet, and an upperlayer formed in superimposed relation upon said inner layer and of relatively low flexibility but greaseproof in its characteristics, said layers being interbonded whereby the high flexibility inner layer serves to maintain unbroken thecharacteristics of the upper layer against disruptive effects of bending and the like in use 28. A -grease'proof and waterproof paper prod'- not of the character described, comprising a hard sized sheet" having a grease'proofing surface stratum upon said hard sized sheet consisting of superimposed layers, said layers comprising an inner formed layer of high flexibility bonded to tively low fiexibilitybut greaseproof in its characteristics, said layers being interb'onded where-.

by the. high flexibility inner layer serves to maintain unbroken the characteristics of the upper layer against disruptive- F'efi'ects of b ending and the like use, and an: moistureprooflng agent.

29. A greaseproof 'and'waterproof paper product of the character described, comprising a hard overlying t'op or a surface, said surface comprising a lower layer which includes a substantial proportion of a rubber compound and has high flexibility, and an upper layer which includes a substantial proportion of an oil insoluble greaseprooflng agent and has high greaseproofness, the said layers and the said hard sized sheet being'relatively interbonded to maintain the continuity of said surface material against disruptive effects during use due to bending and the like. I

30. A paper product of the character described having a greaseproofing surface stratum thereon consisting of superimposed layers, said layers comprising an inner layer of high flexibility including a rubber material, and an upper layer formed in superimposed relation upon said inner layer and of a relatively low flexibility but greaseproof in its characteristics, said paper product and layers being relatively interbonded, whereby the high flexibility inner layer serves to maintain unbroken the greaseproof-mg characteristics of.

hydric alcohol and having high greaseproofness,

said sheet and composite coating being flexible to maintain the continuity of saidcompos ite coat ing,against disruptive effects in use due to bending and the like 32. The method of forming a greaseproof sheet,

which comprises applying to-the paper sheet a layer of fluid material containing constituents having high flexibility and paper bonding characteristics, forming said applied layer into a highly flexible layer bonded to said sheet, applying upon said formed layer a layer of fluid material containing constituents giving high greaseproofness, and forming said second applied layer into a greaseproof layer of comparatively 10W flexibility superimposed upon and interbonded with said first formed layer, whereby the highflexibility inner layer serves to maintain unbroken the. characteristics of the upper layer against the disruptive effects of bending;

33. The method of forming a greaseproofsheet,

which comprises applying to the paper sheet a layer of fluid material containing constituents giving high flexibility and having paper bonding characteristics, applying upon said layer a fluid material containing constituents giving high greaseproofness, and forming said second applied layer into a greaseproof layer of comparatively 'low flexibility superimposed 'upon and interbonded with said first applied'layer, whereby the high flexibility inner layer broken the greaseproofing characteristics of the upper layer against the disruptive effects of bending a lower coating layer having high flexibility and forming the base coating, and an upper. coating layer having high greaseproofness, said sheet and composite coatingbeing flexible to maintain the continuity of said composite coating against serves to maintain ungreaseproof sheet like.

disruptive effects in use due to bending and the 35. A method of forming a greaseproof sheet which comprises applying a surface sizing to the sheet, then applying a composite greaseproef coating to the surface of the sized sheet including a lower coating layer having high flexibility and forming the base coat, and an upper coating layerhaving high greaseproofness, and then applying an overlying moistureproof coat over the composite greaseproof coating, said sheet and composite coating being flexible to maintain the continuity of said composite coating against disruptive effects in use due. to bending and the like. i

sheet which comprises applying a surface sizing to the paper sheet, then applying a composite greaseprooflng coating to the sized surface of the sheet including a lower coating layer having high flexibility and forming a base coat, and an impervious upper coating layer having high greaseproofness overlying the base coat, and then applying a top odor-eliminating coating over the composite 'greaseproof coating, said sheet and composite coating being flexible to maintain the I sheet and composite coating being flexible to maintain the continuity ofsaid composite coating against disruptive effects in use due to bending and the like. 7

38. The method of forming a greaseproof paper sheet. which comprises applying a composite greaseproofing' coating 'to a traveling web of paper including a lower flexible coat containing rubber latex, and an upper coat containing a greaseprooflng agent, and then applying a solutionto the coated surface of the sheet, said .sheet and composite coating being flexible to maintain the "continuity of said'jcomposite coating against disruptive effects in use due to bendcover the surface with an inorganic layer elimiing and the like.

39. A method of forming-a greaseproof paper sheet which comprises applying a composite greaseprooflng coating toa traveling paper web including a base coat havingihigh flexibility and an overlying coat having high grease'proofness,

subjecting the coatings on the traveling coated 36. A method of forming a greaseproof paper web before drying to' smoothing and spreading action and then to. drying fluid blasts after the several coats, said isheet and'composite coating being flexible to maintain the continuity of said the traveling web a top moisture-proofing coat of a water insoluble wax, and then subjecting the coated sheet to pressure, said sheet and com-, posite coating being flexible to maintain the continuity of said c ornposite coating against disruptive effects in use'due to bending and the like.

'41. Themethod of forming a 'greaseproof paper sheet which comprises applying. to the sheet a coating having high flexibility to form a base 7 coat thereon, then applying to the coated'surface of the sheet an overlying coating having high greaseproofness and finally applying 'a top coat of alkaline silicate to eliminate odor, said sheets and said coatingbeing flexible to maintain the continuityof said coatings against disruptive effects in use due to bending and the like.

42. The method of forming a greaseproof paper sheet which comprises applying to a paper sheet a coating including rubber l'atexrto form a flexible base coat thereon, then applying to the coated surface of the sheet an overlying coating including casein and having high greaseproofness and flnally' applying a top coat to eliminate odor. said sheet and said coatingsbeing flexible to maintain the continuity of said coatings against disruptive effects in use due to bending and the like. I

J 43. The method of forming a greaseproof paper [sheetwhich comprises applying to a paper sheet a coating including rubber latex to form a flexible base coat thereon, then applying to the coated surface of the sheet anoverlying coating including casein and having high greaseproofness, and

finally applying a top coat including an inorganic silicate and formaldehyde, the formaldehyde in the top coat serving to flx the casein in the adjacent coating and the inorganic silicate serving to

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