US2416734A - Greaseproof paper - Google Patents

Description

' March 4, 1947. J. K. BOGGS arm. 2,416,734

GREASEPROOF PAPER Filed June 10, 1943 GREASEPROOF SHEET LAMINATING ADHESIVE INCLUDING I I CORROSION INHIBITOR CELLULOSIC AND BUFFER BASE SHEET 7 Imue HTOILS Jffff KENNETH 6066f 650A 66 H. Jl/lL/l/A/V Patented Mar. 4, 1947 GREASEPROOF PAPER Jesse Kenneth Boggs,

George H. Sullivan, signors to Rapinwax apolis, Minn., a corpo 9 Claims.

Our invention relates to an improvement in grease-proof papers, wherein it is desired to provide a paper which is grease-proof and which is stable within predetermined limits of hydrogen ion concentration and total acidity, and which has no corrosive action on steel.

Considerable difficulty has been experienced in the wrapping of articles and parts formed of steel and other corrodible materials. In the wrapping of articles and parts used for the Army and Navy, for example, definite limits are placed upon the hydrogen ion concentration in the paper, and also upon the total acidity in the paper. stance, regulations state that in the packing of precision parts where contact of the packaging material with a critical surface of the part may cause corrosion, the pH value of the finished paper must be between 6.5 and 7.5. At the same time the water-soluble acidity must be less than 10% equivalent sulfur trioxide.

Considerable trouble has been experienced in maintaining the proper pH range in the paper.

We have found that the pH of the paper varies considerably in different climatic conditions. It is therefore an object of the present invention to provide a product capable of maintaining a predetermined pH range over varying climatic conditions.

An object of the present invention lies in the provision of a substantially neutral non-corrosive Wrapping material comprising a cellulosic base containing a minor amount of a water-soluble buffer and corrosion inhibitor. We have found that certain products act both in the capacity of a buffer to prevent variation in the hydrogen ion concentration of the finished sheet and also as a corrosion inhibitor to prevent a. corrosive action on the wrapped material. We therefore desire to embody such products in small amounts in a cellulosic base wrapping material in order to provide a grease-proof sheet which will be noncorrosive in contact with precision parts of steel or other corrodible material.

We have found that when orthophosphoric acid reacts with certain organic amines a product is formed which is suitable for use both as a buffer and a corrosion inhibitor. LAS a result through the use of such products We have been able to not only buffer the wrapping material to the desired pH range, but also to provide in the paper a corrosion inhibitor which will definitely inhibit the corrosion of metallic parts which contact the wrapping sheet. I

A further feature of the present invention lies in the fact that our buffering material may make the pH range of a wrapping sheet stable at a substantially neutral point with a sufficiently small amount of the product to give a total acidity in the wrapping sheet of less than .1%. As a result our buffering material may be used in wrapping Wilmington, Del., and

Minneapolis, Minn., as- Paper Company, Minneration of Minnesota Application June 10, 1943, Serial No. 490,310

For int sheets for wrapping precision parts within the present Government specifications for a. grade A ordnance paper. This smallamount of buifering material is also sufficient to inhibit substantially the corrosion of metal parts wrapped.

A feature of the present invention lies in the fact that diamylamine phosphate for example, is capable of buffering wrapping paper to a pH range of between 6.5 and 7.5 when desired. At the same time in the amount of diamylamine phosphate used, the total acidity of the product is less than the maximum acidity permitted in Government specifications for such a Product. Not only will diamylamine phosphate act to buffer the paper, but also this product acts as corrosive inhibitor for the protection of metal parts wrapped.

A feature of the present invention lies in the fact that our buffer is capable of stabilizing neutral paper so as to retard its tendency to become acid or basic upon aging. By use of this invention it is a relatively simple task to change the pH of a wrapping paper which is outside of the proper pH range, to a pH which is satisfactory. An even greater task is to protect a paper so that it will remain within this pH range for an extended period of time. However, when this invention is practiced by one skilled in the art this advantage can readily be accomplished. We have found that wrapping papers including our bufiering and corrosion inhibiting compounds will remain stable for an extended period of time and under a considerable range of climatic conditions.

'Another very desirable feature of the present invention lies in the fact that our buffering and' corrosion inhibiting ingredients may be embodied in plasticized paper. Plasticized paper is to be highly preferred for wrapping purposes as such paper is soft, pliable, very easy to handle and less likelyto crack in folding or bending. It also retains-its grease-proof properties, even when creased severely. However, plasticized paper is ordinarily considered to be too corrosive touse for wrapping materials which are easily corroded. For this reason plasticized wrapping papers have hitherto been considered impractical for this purpose. In practicing our invention, however, we have found that when plasticized paper contains our bufferin and corrosion inhibiting materials this paper is no more corrosive than untreated or unplasticized paper. Thus we have found that it is possible plasticizers such as glycerin, for example, without danger of corroding the parts wrapped. It thus becomes apparent that our invention has resulted in great improvement in the finished wrapping material.

A further feature of this invention lies in the fact that the paper is quite stable in pH during the processing operations after the corrosion into use paper containing hygroscopic hibitor has been added. Thus if our inhibiting ingredient is used, ordinary non-technical operators can follow various normally used procedures common to processing of paper without the necessity of changing the processes. This results in a much cheaper operating cost and a lower priced finished wrappin material.

,Still a further feature of the present invention lies in the use of an inhibited, plasticized starch solution as a laminating agent in the formation of grease-proof papers. Such papers have usually been formed of sheets of cellulosic material such as ordnance kraft and ordnance grease-proof paper laminated with wax. We have found that after a period of time a contacting oil film will penetrate the grease-proof sheet and creep into the wax lamination from the edges sufficiently to actually dissolve the wax between the sheets. As a result, the lamination will separate very easily, and the kraft sheet on the outside will be saturated with oil. However, where the sheets are laminated with a starch solution containing a hygroscopic material such as glycerol and our buffering and corrosion inhibiting material, the oil or grease cannot dissolve the laminating film, and absorbed in the outer kraft sheet.

These and other objects and novel features of our invention will be more clearly and fully set forth in the following specification and claims.

In the drawing the figure illustrates a portion of a laminated sheet showing the corrosion inhibitor and buffer incorporated in the laminating adhesive.

In the formation of grease-proof papers to be used in wrapping corrosive materials, it is desirable that the paper have a pH range of 6.5 and 7.5 and a total acidity of not more than 0.1% by weight as su1phur trioxide. We have found that while it is readily possible to manufacture a pa per which comes within these specifications, the pH of the paper will vary widely upon aging. As the result, a paper which meets the specifications when manufactured may not come within the desired pH range after being exposed to atmospheric conditions for a time.

A further difficulty experienced with such wrappings lies in the corrosive effect of the papers upon the parts wrapped. These papers will allow corrosion of metal parts after contact therewith for a period of time. Accordingly, a means for inhibiting the corrosive effect of the paper upon the metal is of the greatest importance.

We have found that a certain class of materials may be used to act both as a buffer to maintain the pH within the proper range and also to inhibit corrosion of the metallic part in contact with the paper. Thus, by the practice of this invention and the use of these compounds in paper, the paper may not only be rendered resistant to change of pH, but also relatively noncorrosive to metal parts.

When a selected organic amine is reacted with orthophosphoric acid, a.. reaction product is formed which not only acts as a buffer, but also as a corrosion inhibitor. While other organic amines may form successful corrosion inhibitors and buffers when reacted with orthophosphoric acid, we have found the following organic amines successfully operable for the purpose:

(a) Primary alkyl amines containing from 2 to '7 carbon atoms.

(b) Primary alkanol amines containing 1 to 8 carbon atoms.

() Secondary amines of the formula:

from

little of the Oil film will be in which D and E may each be any alkyl or alkanol group from 1 to 6 carbon atoms.

(d) Tertiary amines of the formula:

in which at is either 1, 2, or 3.

(h) Benzyl amine.

As examples of primary alkyl amines containing from 2 to 7 carbon atoms with which the reaction product with orthophosphoric acid is suitable, we might name the following:

M Ml. of Primary amine Manufacturer a 85% Monocthyl amine (70%) Sharples 100 Mono-isobutyl amine do. 100 40 Benzyl amine Eastman 100 33 Monoethanol amin 100 60 Ethylene diamine 230 164 Tetraethylenc pentamine ..d0 200 130 As examples of secondary amines whose orthophosphate is suitable, we might use:

M1 M]. of Secondary amine Manufacturer a 85% H PO4 Diethyl amine Sharples 130 50 Diamy1aminc.. o.. 250 Diethanol amine. Carbide & Carbon 100 48 Morpholine -.do 300 180 As examples of the tertiary amines which may be reacted to form the orthophosphate and used satisfactorily we give:

As examples of the quaternary amines whose orthophosphates are desirable combined corrosion inhibitors and buffers we give:

M1 Ml. of Quaternary amine Manufacturer a 3 l Tetraethanol ammonium..- Hydroxide 40% solution) In the above table the manufacturers name is not given in full. The name Sharples refers to the Carbide & Carbon phosphoric acid in the proportions mentioned to tially neutral point in the pH range with a suinprepare the amine phosphate salts. These salts ciently small amount of corrosion inhibiting maare incorporated into grease-proof papers by any terial to give a total acidity by titration not exof the methods well known to the trade and proceeding 0.1% by weight as sulphur trioxide (SOa). ducing a high grade grease-proof oil-proof, anti- We have also found that this amount of corrocorrosive, neutral paper. sion inhibiting compound is also sufiicient to in- In testing the foregoing alkyl and alkanol prihibit the corrosion of metal parts which are mary, secondary, tertiary and quaternary amine wrapped in it. Good results both with respect to phosphates, solutions were made up with distilled buffering the pH of the paper and inhibiting the water having a pH of 6.7 to 7.0 after boiling. corrosive properties thereof have been obtained Tests were made to determine the pH of the sowith as little as .01% amine phosphates. On the lution when it was made in concentrations of other hand as much as 65% of suitable amine 10%, 1.0 0.1% and of 0.01 respectively. phosphates may be used in the paper without in- Tests were also made to determine the number of creasing the total acidity by titration to exceed ml. of 0.01n NaOH required to bring 250 cc. of .1% by weight 'as'sulfur trioxide (S03). Accordthe 0.1% solution of these amine phosphates to a ingly from .01% to 6.5% suitable amine phospH of 8.4. As an empirical test, steel panels were phates may be used in the paper without going immersed in 1% aqueous solutions of the amine beyond the limits specified for a grade A ordnance phosphates in order to test the corrosion properpaper by present Government specifications. ties thereof. The results of these tests are tabu- For actual use we have found that the total lated as follows: acidity in the paper may be increased substan- PRIMARY AMINE PHOSPHATES Ml. Mono-ethyl amine phosphate 6. 7 6. 6 6. 7 6. 8 74 No corrosion or pitting. Mono-isobutyl amine phosphate. 6. 9 6. 9 7. 0 6. 9 64 Do. Benzyl amine phosphate 6. 6 6.8 6.9 6.8 105 Do. Mono-ethanoi amine phosphate.-- 6. 9 7. 0 7. 1 7. l 56 Do. Ethylene diamine phosphate 7. 1 6. 9 6. 8 6.8 Do. Tetraethylenc pentamine phosphate 6. 9 6. 6 6. 7 6. 7 145 Do.

SECONDARY AMINE PHOSPHATES Ml. Diethyl amine phosphate. 6. 8 6. 6 6. 8 6. 8 No corrosion or pitting. Diamyl amine phosphate. 6.8 6.9 7.0 6.9 56 Do. Diethanoi amine phosphate 6.9 6.9 7.1 7.1 136 D0. Morpholine phosphate 6.8 6.9 6.8 6.8 60 Do.

TERTIARY AMINE PHOSPHATE M7. Triethylamine phosphate 6. 7 E. 6. 6 6. 7 6. 7 72 No corrosion or pitting. Tri isopro annl amine hos hate 6.9 6.9 7.0 7.0 70 Do. Di-n-buty ethanol am iep osphate 7.0 7.1 7.3 7.2 54 Do.

QUATERNARY AMINE PHOSPHATE Tetraethanol ammonium phosphate 6. 8 7. 1 7.3 7. 2 140 No corrosion or pitting.

DISTILLED WATER M2. 7. 0 7. 0 7. 0 7. 0 0. 8 Badly corroded and pitted.

I All solutions made up with distilled water having a pH equal to 6.7 to 7.0 after 3011:1125. l M1. or .01n NaOH required to bring 250 c. c. of 0.1% solution of compound to pH eq 8.4. I Immersed in 1% solution of compound for 16 hours at 70 degrezs F.

From the foregoing table it will be obvious that 60 tially beyond 1.7% without injurious eflects on the amine phosphates of the various classes decorrosive material wrapped, Apparently themscribed actually reduce corrosion when in contact creased cost and odor of the paper would be the with steel plates and that distilled water alone is limiting factors on the percentage of amine phosvery corrosive to such metal parts. phates which may be used in the paper.

- A a result it is evident that not only will paper Example I.Diamylamine phosphate is used containing such amine phosphates be bufiered as a bufier and corrosion inhibitor in a 25 pound to the proper pH range, but in addition the paper (24 x 36-480 ream) sheet of grease-proof paper. will inhibit corrosion in the product which is The dry grease-proof sheet is impregnated with wrapped. This is extremely important, particu- 1.9 pounds of a 5.3% water solution of diamyllarly in the wrapping of precision or ordnance amine phosphate. Impregnation is accomplished parts where corrosion must not take place if these by passing the sheet through a Mayer coater with Parts are to be in proper condition when unthe diamyiamine phosphate solution in the pan. wrapped for use. The sheet is then dried on ordinary steam roll We have found that it is commercially feasible dryers, leaving the diamylamine phosphate in the to butter paper and make it stable at a substansheet. The following shows the efiect of this compound on the pH, total acidity, and corrosive properties of the sheet:

Corrosion of steel plates wrapped in paper Corrodcs steel plates badly. No corrosion of steel plates.

Per cent 25 lb. grease-proof untreated... 0.006

25 lb. grease-proof treated with 7.0

llinmylmnine phosphate.

Because of the highly corrosive action of papers containing hygroscopic materials such as glycerin, it is present practice to prohibit the use of the paper containing hygroscopic material such as glycerin, the corrosive effect of the paper upon the material wrapped is greatly decreased. As a result by the use of our corrosion inhibiting and buffering compound we have been able to produce a plasticized wrapping sheet, which is relatively non-corrosive to materials wrapped. As the result an improved wrapping sheet may be provided which is extremely stable, which is non-corrosive, and which may be folded and flexed without injuring the fibrous structure of the sheet.

Example H.Diamylarnine phosphate is used as a buffer and corrosion inhibitor in a laminated, glycerine plasticized sheet of grade A ordnance such as kraft paper and a grease-proof paper, or a grease-proof regenerated film with a waterproofing material such as wax and the like. We have found that when oil seeps through or around the grease-prooffilm and/or paper this oil has a tendency to dissolve the wax and thereby causes easy separation of the laminations. We therefore prefer to laminate the paper and grease-proof film and/or paper with a material insoluble in oil such as starch or modified starch solution as illustrated in the drawing. As a result should oil contact the laminating material separating the grease-proof film and the outer kraft sheet no tendency for separation of the laminations is provided.

Example III.Diamylamine phosphate is used as a buffer and corrosion inhibitor in a starch laminating solution used to laminate a twentyfive pound grease-proof'sheet to a thirty pound kraft sheet. The laminating solution is made up as follows:

Substantially forty parts by weight of the above 7 ingredients are mixed with substantially sixty greaseproof paper. A sheet of 40 pound greaseproof is laminated to a sheet of 30 pound kraft with microcrystalline wax on the Mayer coater. The greaseproof side of this sheet is then impregnated with 8 pounds of solution made up as follows:

Per cent Glycerine by weight 50 Distilled water by weight 49.5 Diamylamine phosphate 0.5

The sheet thus impregnated is wound into a roll and allowed to stand so as to complete the impregnation of the above solution and thereby produce a tough, flexible laminated sheet.

The following test results show a comparison between the sheet produced as described in thi Example II and similar sheets, one of which was plasticized with glyccrine Without diamylamine phosphate, and the other of which was not plasticized or inhibited with diamylamine phosphate.

In the formation of grease-proof papers it has been common practice to laminate sheets of paper parts by weight of water. The sheets of kraft and grease-proof are laminated together on a Mayer coater with the above solution and the resultant two ply sheet is dried to form a well laminated sheet.

The following test results show the efiect'of the diamylamine phosphate on the pH, total acidityand corrosive action on the finished sheet.

pH '1. A. Corrosion Percent Sheet laminated with stnrcll- 7.6 0.003 Bad corrosive glycorinc. No diamylmninc eiicct. phosphate. Shoot laminated with starch- 6.9 .052 No corrosive glycerinc. With dinmylaminc elicct. phosphate.

We have found that when corrosive materials are wrapped in any of our grease-proof sheets, less corrosion is experienced on the contacted parts than with any other grease-proof sheet with which we are familiar. We have further found that the pH of the paper remains stable over wide variations of climatic conditions and upon aging.

To one skilled in the art it is obvious that the use of these amine phosphates as combined buffering and corrosion inhibiting compounds is not limited alone to paper base wrapping materials, but can be used with any base material where these properties are desired in the same prodnot.

A non-corrosive tape may be made by slitting the paper of any of the above examples into suitable widths. Cartons or packages may likewise be formed of the various non-corrosive base stocks which may, obviously, be of any desired weight to serve the intended purpose.

In accordance with the patent statutes, we have described the principles of composition of our grease-proof sheet material and while We have endeavored to set forth the best embodiments thereof, we desire to have it understood that minor changes may be made within the scope of the following claims without departing from the spirit of our invention.

We claim:

1. A non-corrosive wrapping material comprising a cellulosic base containing a minor amount of a water soluble buifer and corrosion inhibitor which comprises the reaction product of'orthophosphoric acid and an organic amine chosen from the class consistsing of (a) Primary alkyl amines containing'from 2-7 carbon atoms,

(b) Primary alkanol amines containing from l-B carbon atoms,

() Secondary amines of the formula in which D and E may each be any alkyl and/or alkanol group or from 1-6 carbon atoms,

(d) Tertiary amines of the formula in which F, G, and H may each be any alkyl group of from 1-2 carbon atoms and/or any alkanol group from 1-3 carbon atoms,

(e) Water soluble quaternary amines,

(j) Morpholine,

(g) Ethylene diamine and polyamines with the formula in which a: is either 1, 2, or 3,

(h) Benzyl amine. 2. A non-corrosive wrapping material comprising a cellulosic base containing a minor amount of a water soluble bufier and corrosion inhibitor which comprises a phosphate of an organic amine chosen from the class of amines consisting of:

(a) Primary alkyl amines containing from 2-7 carbon atoms,

(b) Primary alkanol amines containing from 1-8 carbon atoms,

(0) Secondary amines of the formula in which D and E may each be an alkyl and/or alkanol group of from 1-6 carbon atoms,

(d) Tertiary amines of the formula in which F, G, and H may each be any alkyl roup of from 1-2 carbon atoms and/or any alkanol group from 1-3 carbon atoms,

(6) Water soluble quaternary amines,

(f) Morpholine,

(g) Ethylene diamine and polyamines with the formula in which a: is either 1, 2, or 3,

(h) Benzyl amine.

3. A non-corrosive wrapping material comprising a cellulosic base containing as essential ingredients a hygroscopic plasticizing material and a minor amount of a water soluble buffer and corrosion inhibitor which comprises the reaction product of orthophosphorlc acid and an organic amine chosen from the class consisting of:

(a) i y alkyl amines containing from 2-7 carbon atoms,

(b) Primary alkanol. amines containing from 1-8 carbon atoms,

(0) Secondary amines of the formula in Which D and E may each be any alkyl and/or alkanol group of from 1-6 carbon atoms,

(:1) Tertiary amines of the formula H in which F, G, and H may each be any alkyl group of from 1-2 carbon atoms and/or any alkanol group of from 1-3 carbon atoms,

(e) Water soluble quaternary amines, (f) Morpholine, (g)- Ethylene diamine and polyamines with the formula.

NH2-(CH2CH2NH)1CH2CH2NH2 in which a: is either 1, 2, or 3, i

(h) Benzyl amine.

4. A non-corrosive wrapping material comprising a cellulosic base containing as essential ingredients a. hygroscopic plasticizing material and a minor amount of a water soluble butler and corrosion inhibitor which comprises the phosphate of an organic amine chosen from the class of amines consisting of (a) Primary alkylamines containing from 2- carbon atoms,

(12) Primary alkanol. amines containing from 1-8 carbon atoms,

(c) Secondary amines of the formula in which D and E may each be any alkyl and/0r alkanol group of from 1-6 carbon atoms,

((1) Tertiary amines of the formula F g a in which F, G, and H may each be any alkyl group of from 1-2 carbon atoms and/or any alkanol group from 1-3 carbon atoms,

(e) Water soluble quaternary amines, (,f) Morpholine, (g) Ethylene diamine and polyamines with the formula in which D and E may each be any alkyl and/or aikanol group of from 1-6 carbon atoms,

(d) Tertiary amines of the formula o-w n in which F, G, and H may each be any alkyl group of from 1-2 carbon atoms and/or any alkanol group from 1-3 carbon atoms,

(e) Water soluble quaternary amines.

(I) Morpholine,

(g) Ethylene diamine and formula in which a: is either 1, 2. or 3.

h) Benzyl amine.

6. A non-corrosive wrapping material which comprises a cellulosic base sheet and a greaseproof film laminated with a starch adhesive including a minor amount of a water soluble buffer and corrosion inhibitor comprising a phosphate of an organic amine chosen from the class of amines consisting of 1 Y (a) Primary alkyl amines containing from 2-7 carbon atoms,

(1)) Primary alkanol amines containing from 1-8 carbon atoms,

() Secondary-amines of the formula in which a: is either 1, 2, or 3.

( h) Benzyl amine.

poiyamines with the 7. A non-corrosive wrapping sheet comprising i a series of celiulosic base sheets laminated with a starch adhesive containing a minor amount of a water soluble buffer and corrosion inhibitor which comprises the reaction product of orthophosphoric acid and an organic amine chosen from the class consisting of (a) Primary alkyl amines containing from 2-7 carbon atoms,

(bl Primary alkanol amines containing from 1-8 carbon atoms,

(0) Secondary amines of the formula in which D and E may each be any alkyl and/or alkanol group of from 1-6 carbon atoms. (d) Tertiary amines of the formula in which F, G, and H may each be any alkyl group of from 1-2 carbon atoms and/or any alkanol group from 1-3 carbon atoms,

(e) Water soluble quaternary amines.

(f) Morphoiine,

g) Ethylene diamine and poiyamines with the formula in which a: is either 1, 2, or 3.

h) Benzyl amine.

8. A non-corrosive wrapping material comprising a series of ceilulosic base sheets laminated with a starch adhesive containing a minor amount of a water soluble buffer and corrosion inhibitor which comprises a phosphate of an organic amine chosen from the class of amines consisting of:

a) Primary aikyl amines containing from 2-? carbon atoms,

(b) Primary alkanol amines 1-8 carbon atoms,

0) Secondary amines of the formula containing from L b in which D and E may each be any aikyl and/or alkanol group of from 1-6 carbon atoms. (d) Tertiary amines of the formula in,which F, G, and H may each be any alkyl group of from 1-2 carbon atoms and/or any aikanol group from 1-3 carbon atoms,

(e) Water soluble quaternary amines,

(f) Morpholine,

(g) Ethylene diamine and polyamines with the in which a: is either 1, 2, or 3.

(h) Bcnzyl amine.

9. A non-corrosive tape comprising a strip of cellulosic base material which contains a minor amount of corrosion inhibitor which comprises a water soluble bufier material and which is an orthophosphate of an organic amine chosen from the class consisting of:

(a) Primary alkyl amines containing from 2-7 carbon atoms,

(b) Primary alkanol amines containing from 1-8 carbon atoms,

(0) Secondary amines of the formula E in which D and E may each be any alkyl and/or alkanol group of from 1-6 carbon atoms. ((1) Tertiary amines of the formula in which F, G, and H may each be any alkyl group of from 1-2 carbon atoms and/or any aikanol group from 1-3 carbon atoms,

(e) Water soluble quaternary amines,

(f) Morphoiine,

' 13 14 g) Ethylene diamine and polyamines with the REFERENCES CITED formula The following references are of record in the NHz\CH2CH2-NH)x-CHZCHZNHQ fil o thi paten in which a: is either 1, 2, or 3, 5 UNITED STATES PATENTS (h) Benzy] amine- Number Name Date 03,619 Armor July 23, 1940 JESSE KENNETH BOGGS. 2,181,811 Hughes NOV. 28, 1939 GEORGE H. SULLIVAN. 2,196,261 Howland Apr. 9, 1940

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