US 2578324 A
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Description (OCR text may contain errors)
Dec. 11, 1951 c. A. sou'rHwlcK, JR 2,578,324
I DESICCANT POUCH Filed Sept. '7, 1945 Patented Dec. 171, 1951 DESICCANT POUCH Charles A. Southwicii, Jr., Mount Vernon, Ohio, 'assigner vto Shellmar Products Corporation, Mount Vernon, Ohio, a corporation of Delaware Application September 7, 1945, Serial No. 614,985
v3 Claims. (Cl. 18S-4.8)
The present invention relates to improvements incoated sheet material. More particularly, it pertains'to a Water vapor permeablev sheet material having a heat-scalable coating thereon with a water vapor permeable material embedded in the coating, thereby providing a combined heat-scalable structure having increased 'Water lvapor transmission characteristics, vand iibrous sheet, `a finely divided fibrous material,
Which also has a relatively high rate of water vapor permeability, embedded in the coating in such -a manner that its fibers extend through- `out the coating so that Ysome of them are exposed at the coating surface and some of them are exposed to contact with the brous base sheet, the fiber impregnated coating'being rendered increasingly water vapor permeable by the .embedded fibrous material whereby the water vapor transmission characteristic `of the combined construction is considerably enhanced.
Yet more specifically, it is an object of the invention to provide a package made of lsheets of iibrous container material having a relatively high .rate of water vapor .permeability, a heatscalable coating on each of the sheets, Yand a finely divided iibrous material which also has a relatively high rate of water vapor permeability which is embedded Within the coating, the sheets being arranged into container or pouch formationwththe coating material on the inside and being heat-sealed where it is in face-to-face seam formingfrelationship, the fibrous embedded material in the coating strengthening the seam structure, and the container, or pouch, being provided with a desiccant, whereby water Vapor readily can be absorbed through the walls thereof `at an increased rate.
Other objects of the invention will in part'be obvious and will in ypart appear hereinafter.
The inventionaccordingly comprises an article of manufacture possessing the features, properties, and the relation of elements which will be exemplified in the .article .hereinafter described and the scope of the-application of which will .be indicated in the claims.
For a fuller understanding of the nature `and objects of the invention reference should be had to the .following `detailed description taken in connection with the accompanying drawings, in
which: .i 4
Fig. l is a diagrammatic illustration of an `apparatus 'for practicing a method embodying the invention of combining fibrous sheets by means of a coating composition so that one sheet is embedded within 'the coating;
Fig. 2 is a perspective View of ya fragment, on an enlarged scale, o'f a fibrous coated sheet with another sheet embedded in the coating;
Fig. 3 is a plan viewof a type of container, or pouch, made from such coated sheets with a corner portion removed to show the contents;
Fig. 4is an end `elevation-al View with a portion broken Vaway, and partly in section,illustrating the pouch, or container, ofliig. 3; and
Fig. 5 .is a fragmentary portion taken through the heat-sealed'seam construction, for example, on the line of Fig. 3, on an enlarged sca-le further illustrating another feature of the invention.
Pouches, or containers, made from coated container material embodying the present invention, when iilled `with a desiccant such as silica geLtare useful when placed in bags'or containers of lall sizes .protectively covering mechanisms or instruments where it is desirable hermetically to package them and to keep them free from moisture. During Vthe initial stage of Wrapping Aor packaging"sucharticles, and after they are'hermetically sealed in the package, it is essentialto remove as much'moistureas possible. This previously has been done by putting cloth bags icontaining desiccants, such as silica gel, therein to absorb the :moisture or vapor confined Within the container. However, such containers have proved to `be expensive because they are'handmade and require special linings to render them sift proof and dus'trtight vand the walls have not had 'the necessary high moisture vapor transmissive characteristics to enablethem lrapidly to transmit moisture.
rThe foregoing diiiiculties and other disadvantages have'been overcomebymeans of `rthe present 'invention wherein a coated material, for
making pouches containing va desiccant, is uti` Referring more particularly to Fig. 1 of the drawings there is illustrated a suitable appara-k tus for practicing the present invention. A'mill roll te, for example, of kraft paper'is unwound to provide avveb i Whichpasses around an. idler roller i2. Running `be*|.weer1'the idler roller I2 and the web Il is another-'web I3 `coming off a mill roll ill, for example, of ttissue paper.,V Anl example of the kraft paper employed would be a 30 pound weightper ream. An example of the tissue would be a pound weight per ream.
Both webs II and I3, after they pass a-round the idler roller I2, form a double web I5 which passes around idler rollers I6, I'I and I8. The double web is then run around a drum, or cylinder, I9 rotating in a bath of heat-sealable adhesive coating 26 in a trough 2li. A suitable coating material, for example, is a vinyl chloride acetate copolymer, or a butyral lacquer. The double web I5 is passed around the drum I9. The heavy kraft web II lies against the drum surface and the kraft tissue web I3 is exposed to the coating material. As the drum is rotated, the web II becomes coated and the tissue is ernbedded in, or impregnated with the coating of heat-scalable material.
As the combined web travels toward the top of the drum the excess coating material is caused to fiow back into the tank because of the pressure of a squeeze roller 22. Any suitable leveling device 23 can be positioned above the coated web I I carrying the tissue embedded fibrous material and this leveling device knocks down ridges and irregularities in the surface of the coating.
In Fig. 2 the kraft sheet II illustrates the numerous fibers which transmit to the sheet its water vapor' permeable characteristics. It will be appreciated from the illustration that the coating material has embedded therein the fibrous tissue web I3 and that the ends of the tissue material tend to become exposed at the upper surface of the coating as indicated in the drawings. At the same time these tissue fibers will lie adjacent to or in contact with the fibers of the kraft material I I. The fibers of the tissue I3 provide numerous means of communication for the transmission of water vapor to the kraft sheet II.
It is significant that the coating material 20 is also broken up by the fibers of the tissue I3 additionally to provide numerous minute channels communicating with the kraft sheet II for transmission of water vapor. In this manner a coated sheet is provided which does not carry an adhesively fixed sheet of fibrous material but a thin fibrous sheet which provides a wick action for moisture vapor transmission. At the same time the heat-scalable material strengthens the kraft paper but because of the fact that it is broken up by the numerous tentacles ofthe tissue, it also is rendered very porous and the combined construction has enhanced water vapor transmission characteristics. Furthermore, the heat-sealing characteristics of the coating material is not impaired. Indeed, because of the fibrous tentacles of the tissue I3 embedded in the coating material, two coated surfaces of such a sheet, when brought together under heat and pressure, will combine interlockinglyl to provide a sheet having added strengthening and sealing characteristics in the seam area.
It should be understood that the material with which the coating is loaded need not necessarily be a tissue such as that above described, but preferably such a material is utilized. Any suitable fiocculent material, such as cotton linters, or the like, can be blown or otherwise impregnated into the coating material after it has been "applied to the base sheet of fibrous material II.
It is within the contemplation of the invention that other suitable materials for loading the coating material. can alsoY be. utilized as, for example, a sheet of very finely woven cloth fabric.
A package, or pouch, made from two sheets of material similar to those above describedY is illustrated in Figs. 3 and 4. A desiccant, such as silica gel, is placed in a portion of the pouch and the marginal edges thereof heat-sealed under heat and pressure, the coated surfaces, of course, being in face-to-face relationship.
An illustration of a heat-sealed seam construction embodying the invention is shown in Fig. 5 and it will be appreciated that the fibers in the coating material of such a seam will be intertwined and interlockingly engaged with each other where they are buried or fused in the heatsealable coating.
Another feature of importance is that after the coating operation and during the drying of the coated web impregnated with the tissue or like material, there is an increased rate of solvent migration and evaporation from the coating because of the wicking action of the embedded tissue fibers, many of which are exposed at the surface of the coating. In other words, such a web can be coated and run at high speed and production facilities can greatly be increased.
Itwill-thus be seen that the objects hereinbefore set forth may readily and efficiently be attained, and since certain changes may be made in the above article and different embodiments of the invention could be made without departing from the scope thereof, it is intended that all matter contained in the above description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.
Having described my invention, what I claim as new and desire to secure by Letters Patent, is:
1. A package comprising sheets of fibrous container material having a relatively high rate of water vapor permeability, an overall coating on each of said fibrous sheets, which coating is a heat-scalable material, a finely divided fibrous material which also has a relatively high rate of water vapor permeability being embedded within and evenly distributed throughout said coating so that fibers of said last named fibrous material extend completely throughout said coating, some of which fibers are exposed at the coating surface and some of which are exposed to contact with fibers of said fibrous sheets of container material, said coating being rendered water vapor permeable by said embedded fibrous material, said sheets being arranged into container formation with the coating material on the inside and being heat-sealed where thesheets are in face-to-face seam forming relationship with said fibrous embedded material in said coating thereby strengthening said sea-m structure, and
CHARLES A. SOUTHWICK, JR.
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