US2235765A - Greaseproofing with low ethoxy ethyl cellulose - Google Patents

Description

Within GREASRDOFING WITH LBW ETQXW ETHYL CELLULOSE Harold C. Kelly, Midland, Mich, assignor to The Dow Chemical @ompa y, Midland, Mich, a corporation oi" Michigan No Drang. Application May lid, 1939, Serial No. 27d,653

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This invention relates to wrappers for greasy and oily materials.

An object of the invention is to obtain a wrapping material which is substantially impermeable to grease and oils, and is suitable for packaging oily or greasy substances, such as foodstuffs, and the like.

A further object is to prepare a transparent greaseproof wrapper.

The foregoing and other objects are attained by using as a greaseand oil-proofing agent an organic solvent-soluble ethyl cellulose of ethoxy content less than to per cent. This type of ethyl cellulose will normally contain between 1.75 and 2.25 ethoxy groups per glucose unit and may be termed organo-soluble low ethoxy ethyl cellulose. It is odorless, tasteless, and non-toxic, and forms tough, flexible, transparent films. High or standard" ethoxy ethyl cellulose is not greaseproof, being easily penetrated by oils, fats, greases, and oily waxes. In using the preferred type of ethyl cellulose for greaseproohng, one of two modes of practice may be adopted.

First, films, as such. of low ethoxy organosoluble ethyl cellulose may be used for wrapping. For this use, the him should be of a thickness greater than about .lllll of an inch. Within practical working limits, the higher the viscosity type of ether employed, the more satisfactory is the film for the presentpurpose. The film may or may not contain a plasticizer or coloring matter. For packaging articles which tend to dry out on storage, it is preferred to coat the films on the side which will be turned away from the oily orgreasy article to be enclosed therein with a moisture-proofing composition, for example, a Wax, wax-resin, or wax-resin cellulose derivative composition.

The second mode of practice utilizes organesoluble low ethoxy ethyl cellulose as a coating for ordinary wrapping papers. This coating may be applied by spreading a solution of the cellulose ether composition in an organic solvent on the paper by any of the methods own to the paper coating art, for example, with the aid of a doctor blade, extrusion hopper or roller. itgain higher viscosity types of ethyl cellulose give better protection at equal coating thicknesses, but any low.

ethoxy organo-soluble ethyl cellulose gives good greaseproohng coatings.

The paper should be coated so that a substantially continuous film of the ethyl cellulose composition isformed on its surface. r tins reasoil. it is preferred to coat a smooth surfaced (ml. QL-iit) paper, as continuous, unbroken coatings may be formed on such a paper in thinner layers than on rough or uneven surface papers, thus are quiring smaller expenditure of coating compositions. Suitable papers are highly calendered wrapping papers, lacquered papers, and also such papers as glassine and parchment which already possess a moderate degree of greaseproofness by virtue of the method of their manufacture. e greaseproofness of all these papers is increased by my process and they are given a glossy, attractive appearance. The coating composition may consist entirely of ethyl cellulose or it may contain besides the cellulose ether, plasticizers, resins, pigments, or other common lacquer adjuvants.

According to both modes of practice low ethoxy organo-soluble ethyl cellulose provides a flexible protection for greasy and oily materials whose I edectiveness is not lessened by creasing or heavy Further, films and coatings of low handling. ethoxy ethyl cellulose retain their flexibility and toughness at low temperatures, for example, those in the neighborhood of -4l0 C. and they are accordingly eminently suitable for wrapping frozen foodstuffs.

The following examples illustrate of the invention:

Example f A sample of low ethoxy organo-soluble ethyl cellulose film. (ethoxy content at per cent) was tested in comparison with glassine paper according to the following test.

The sample to be tested is cut into four pieces 2 inches square and each piece is folded to form a box with sides a half inch high and the base 1% inches square. The boxes are held in shape by placing them in suitable supports. A piece of white writing paper is placed beneath each coconut oil, corn oil, and molten hydrogenated stearoleine is added respectively to the four boxes which are then placed in an oven at 70 (1'. Each box is inspected periodically for appearance of a the practice ill box and one cubic centimeter of peanut oil, so

grease spot. When this appears the sample under test is considered to have failed, and the time talren for this failure is recorded. The grease resistance of the sample is reported as the average time of penetration for peanut oil, oil, corn oil, and hydrogenated stearoleine.

The ethyl cellulose him under test had a thickness of .0015 of an inch and its grease resistance was 235 hours. The glasslne paper was the type lmown as coconut m super lard liner parchment of a basis M weight of 43 pounds per ream, and the grease resistance was 44 hours.

Example 2 A greaseproofing test similar to that described in the foregoing example was carried out on a sample of paper coated with a clear film of low ethoxy organo-soluble ethyl cellulose of thickness 0.0016 inch. The grease resistance for this sample was 120 hours.

The invention has particular application in the wrapping of greasy or oily foodstuffs. Examples of such materials are butter, nut meats, potato chips, cheese, baked goods, meat and ice cream.

15 The article may be used as well in packaging other classes of goods which tend to exude oily bodies on storage, and which stain common wrapping papers. Such articles include soaps, candles, and many pharmaceutical products.

Preferred greaseproof wrappers or cartons are those. the entire inner surface 01 which, in contact with the oily or greasy substance, is coated with the organo-soluble low ethoxy ethyl cellulose.

I claim:

The -methodof preventing greasy and oily exudates from paper packages of products tending to give such exudates through paper, which comprises enclosing such products in paper hearing on at least one face thereof a substantially continuous superficial coating of an organosoluble ethyl cellulose having an ether content of from 1.75 to 2.25 ethoxy groups per anhydroglucose unit as the sole substituents, the said coating being tough and flexible, even at subzero temperatures.

HAROLD C. KELLY.