US2445945A - Wrapping sheet for oil-slushed metal articles - Google Patents

Description

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M. w. FORREST Filed May 12, 1945 l'nvenor Marsh/all WIFE rz'ea July 27, 1.948.

WRAPPING SHEET FOR oIL-sLUsHED METAL ARTICLES Patented July 27, 1948 UNITED STATES PATENT oEElcE WRAPPING SHEET FOR OIL-SLUSHED METAL ARTICLES Marshall W. Forrest, Framingham, Mass., as-

signor to Angler Corporation, Framingham, Mass., a corporation of Massachusetts Application May 12, 1943, Serial No. 486,726

4 Claims. (Cl. 154-50) This invention relates to `a wrapping sheet for use on metal parts, such as nely finished parts for airplane engines, which are siushed with oil to protect them during shipment and storage, and

the object is to provide a sheet which' will not accompanying' diagrammatic* andv lunrealistic drawings, wherein:

Fig. l1 is a plan viewcf thesheet with successive-portions broken away and with a conventional indication of craping; and

Fig. 2 is a diagrammatic cross section, thev l thickness of the various layers being exaggerated,

the gure notpurporting to be in any way accurate in its dimensional proportions.A l

Many greaseproof or oilproof wrappers have been'proposed and used. Wrappers for greasy foods, such, for example, as butter, are familiar examples. They are Lgenerally applied to a commodity to enclose the same `and the wrapped article is frequently enclosed in a carton or the like for exterior protection. The greaseproof quality serves to prevent the escape of greasy or oily material to th'e exterior, the purpose being the separation of exterior objects and the greasy material. In the case of oiled machine parts as referred to, it is desirable not only to enclose the oil to prevent it from smearing on an exterior object and to prevent its contamination with dirt but also to preserve the integrity of the film as a protective stratum for the metal object.

In accordance with my invention, therefor, I provide a sheet of substantial character adapted to give to the enclosed article mechanical protection from dirt, abrasion by exterior objects and the like, which, whileritmbodies stratum impenetrable by oil .tolpreventf escapijthereof, presents to the articleea-,zsurfac'ln'fusd with a cor-` rosion inhibiting pifofgliit.4l This product is to a degree analogous tothe oil itself and, while exbe dissipated through the passageways. For this purpose the sheet, while generally flat, may have a rugose surface, preferably provided by resilient embossments such as are secured by the craping process with' the important advantage that if an exterior-pressure on the package tends to push away or wipe off the oil film at the location of the pressure, on release of the pressure the resilient reaction tends to re-establish the film. This action might be referred to somewhat metaphoricallyas a pumping-back eect.

In th'e preferred form as diagrammatically illustrated in the accompanying drawings, the wrapper includes a paper base 6, desirably a sulphate kraft. a thirty-pound ream weight being suitable, the paper being of a chemically neutral character, the hydrogen ion concentration as determined by test No. T435m-34 of the Technical Association of the Pulp and Paper Industry (TAPPI) showing a pH value of 6.5,to 6.9. In itself such a sheet is a durable protection against exterior dirt and abrasive contacts. Its strength' and impervious character are, moreover, substancluding absorption and removal of the film, is

compatible with theslushing oil and may absorb any excess oil while lmaintaining at all times a corrosion-resisting nlm on the metal. The mechanical contact of this infused surface with the enclosed article is preferably such as to maintain.

between the article andthe wrapping minute passageways permitting breathing" so.that,'for example, moisture is not trapped and confined to one locality possibly to cause corrosion, but may tially increased by its infusion with a suitable corrosion inhibiting compound. This compound may include a resinoid base, as, for example, rosin or a surrogate therefor, which is free, however, from deleterious ingredients (the meaning ofthis limitation will hereinafter more fully appear) and an oil or like plasticizing ingredient which may be of the same general character as the slushing oil and may alsohave added thereto a corrosion inhibiting agent. The compound might thus be termed a tempered resin which, while solid at ordinary temperatures, is not brittle but capable of flexing easily with the paper, is amorphous and soft in the sense th'at it has no hard fractured edges and is free of crystalline particles which might scratch highly finished metal. A compound of this nature which I have used in practicescftens at about 200 rF. to form a rather viscous liquid and flows quite freely at about 300 F. Itis neutral, the pH value being from 6.5 to 7.5. Water soluble acidity is less than 0.01% equivalent sulphur trioxide when determined in accordance with VTAPPI test No. T428m-40. The sulphate (S04 test) chloride (Cl test) content combined is less than 0.1% determined in accordance with the methods of the American Society for Testing Materials. The material may thus be termed neutral to steel; that is, it is inert as faras its action on steel when in contact therewith is concerned. It should be noted that the tempering or plasticizing agent, if an oil, is of1non-dryingjchr acter. Both it and the resinoid are substantially unalterable under the conditions of use. That is, the infusing compound as such is chemically inert and unalterable during the preparation of the sheet and the subsequent use thereof, no oxidization, polymerization or condensation being involved. Thus in the case of material as practically used by me a live-hour accelerating aging of a specimen of the wrapping sheet in an oxygen bomb resulted in no detrimental eil'ect on the impregnation.

The impregnating material may be applied tothe sheet in a fused or melted condition at from 300 to 350 F. and is diffused into the body of the sheet conveniently by the process disclosed in the patent to Wheildon No. 1,595,637 and the sheet is conveniently craped as therein described in the same operation to provide a rugose sheet with a multiplicity of irregular resilient embossments. It may be noted thatA the Wheildon patent above referred to specifically refers to the useof asphalt and to prevent misunderstanding it may be well to state here that asphalt as commonly known is entirely unsuitable for the purposes of a mapping of the type under consideration- The infused sheet prepared in this manner .has the tempered resinoid absorbed into the body thereof into the spaces between the fibers, residual air and moisture in the paper being substantially entirely eliminated and displaced thereby, and has a non-tacky surface as indicated by the fact that it may be rolled up without protective sheets between the turns.

In Fig. 2, I have indicated by stippling the infused character of the sheet and have shown very diagrammatically at l the resilient embossments provided by the craping operation.

One face of the sheet 6, opposite to the one which in use is applied to the article, is provided with a stratum impenetrable by oil. The effectiveness of such a stratum may be determined by the turpentine penetration test, TAPPI test No. T454m-42, and although for certain purposes a lesser degree of resistance may be acceptable, I prefer to provide sucha stratum that the wrapper will not allow turpentine to penetrate through it in less than an average'of 1800 seconds. In the exam-ple of the invention chosen for purposes of illustration this oil-resisting stratum, or oil barrier as it may be called, is a pre-formed sheet or layer i0 of cellulose acetate sheeting which is adhered by a suitable adhesive, which may be the same as the infusing compound above referred to, to a kraft paper sheet 12. In Fig. 2 I have not attempted to illustrate separately the uniting layer of adhesive. The assembly of the sheets I0 and l2 may be craped to permit it to expand in the same manner as the base layer 6 and may be united thereto adhesively by a connecting coating I4 of the fusible corrosion inhibiting compound above described which makes a homogeneous union with the impregnant of the base layer I. The joint provided thereby will not separate as the result of normal manipulations of wrapping.

'111e exterior kraft sheet l2 when used and the uniting medium Il provide an additional thickness for the wrapping, increasing its mechanical protective capacity and the sheet I2 provides a surface to which gummed labelsv and the like may be adhesively united.

The infused sheet 6 is not absorbent in the sense that untreated paper would be, and hence when applied to an oil-slushed article has no substantial tendency to blot up or dissipate the oil nlm. nor will therebe va resultant oil saturalit will not in itself cause corrosion but will maintain the protective oil covering. The oil barrier Il. such as the cellulose acetate film described. checks such migration of the oil as might cause dissipation thereof in such manner as to cause impairment of the protective film on the wrapped article or to cause smearing of exterior objects.

An important advantage arises from the craped character ofthe sheet as described in that, as diagrammatically shown in Fig, 2. when itis presented to the surface of the wrapped article A the crests of the crapings l bear on the oil-coated surface and define between them open and irreguiar passageways. Thus moisture on the exterior of the article is not trapped and retained in one spot, where it might possibly pierce the oil film and cause corrosion but maybe dissipated through the passageways, which allow the wrapped article to breathe The embossments 8 provided by the craping process are of a resilient nature and, if flattened A down, tend to return to their original form. Thus if the wrapped articleis subjected to pressure which tends to push or wipe away the oil lm at one locality, on release of this pressure the expansion of the crapings will tend to draw back the oil with a pumping action to its original position. As an indication of the effectiveness of the present wrapper, which I attribute in substantial part to this action, the result of the following test may be cited. A highly polished steel .lournal approximately 2 niches in diameter and having a 11/2 micro-inch finish was slushed with oil and vwrapped with material as herein described and then the package subjected to a pressure of 3000 pounds per square inch. When exposed in a humidity cabinet to a very high degree of temperature and relative humidity, no corrosion was observed. I know of no so-called greaseproof paper consisting of a fiat sheet with'oil-resisting iinpregnation which would attain a like result.

7 'Ihe advantages of resistance to shock due to its resilience and of adaptability to irregular articles due to its differential expansibility are also attained when the wrapper-is craped.

The material is ilexible and adapted to be wrapped or folded about an article in the same manner as any heavy wrapping paper and may be torn from a roll as desired by the use of ordinary ledger blades. I have already referred to the fact that the infused surface is non-tacky in the sense that the wrapper may be rolled up without a protective sheet on this surface. yet easily unrolled, with separation of the turns of the roll. and without objectionable offset of infusing l material on the underlying turn of the roll which, in the case of a wrapper. as shown in Fig. 2, would be the plain kraft sheet l2.

While I have referred to the material as a wrapper such as is formed from the ilat into shape around an article to be enclosed, it may be preformed into bags, envelopes, sheaths, cots or`the like as convenience may dictate.

I am aware that the invention may be embodied in other specific forms without departing from the spirit or essential attributes thereof, and I therefore desire the present embodiment to be considered in all respects as illustrative and not restrictive, as in fact clear ,in several matters from the description itself. Reference is to be had to the appended claims to indicate those principles of the invention exemplified by theparticular embodiment described and which I desire to secure by LettersPatent.

I claim: l

1. A flexible sheet for wrapping oil-slushed metal articles comprising a craped paper basehaving absorbed into the body thereof a normally solid, flexible impregnant and comprising a neutral resinoid and a permanent oil ingredient compatible with the slushing oil, the base presenting at 'one side of the sheet for contact with the article a rugose impregnant-bearing non-abrasive and non-tacking surface, the sheet having a stratum impenetrable by oil exterior to said surface, which stratum is undulating topermit its expansion and contractionl with the base.

2. A flexible sheet for wrapping oil-slushed metal articles comprising a. craped paper base having absorbed into the body thereof a normally solid, flexible impregnant and comprising a neutral resinoid and a permanent oil ingredient com patible with the slushing oil, the base presenting at one sid-e of the sheet for contact with the article a rugose impregnant-bearing non-abrasive and non-tacking surface, and having united to the other face of saidbase a craped assembly comprising a` paper exterior sheet and an interior sheet impenetrable by oil.

3. A iiexible sheet for wrapping oil-slushed metal articles comprising a paper base having absorbed into` the body thereof a normally solid,

oil and comprising a neutral resinoid and a permanent oil ingredient, the base presenting at one side of the sheet for contact with the oily article to be Wrapped an impregnant-bearing, non-abrasive and non-tacking surface, thebase being sive and non-tacking surface, the base being genflexible lmpregnant compatible with the slushing erally flat but the surface being irregular to define a multiplicity of bearing projections and relatively depressed breathing channels, the sheet` comprising, exteriorly of the base, a stratum impenetrable by oil.

` MARSHALL W. FORREST.4

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

UNITED STATES PATENTS Number Name Date 1,882,715 Angler Oct. 18, 1932 1,984,910 Angler Dec. 1.8, 1934 2,069,778 Rowe c Feb. 9, 1937 2,291,838 Shoan Aug. 4, 1942 FOREIGN PATENTS Number Country Date 9,787 Great Britain 1907 580,921 Germany July 18, 1933

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