US2271492A - Moistureproofing composition - Google Patents

Description

Patented Jan. 2?, 134% amps;

morsruanraoorma comosrrro William H. Bryce, Memphis, Tenn.. assignmto Dixie Wax Paper Company, DallaaTex.

No Drawing. Application February Serial No. 258.102 'LClainis. (oi. zoo-m) An object of my invention is to provide a novel coating compound for coating papers used for wrapping bread and other products.

' Another object of my invention i to provide a coating compound which will render a paper for wrapping bread moisture-vapor-prootand pliable.

A further object of my invention is to provide a compound which will melt and liquefy below the boiling point of water without requiring the use of any solvent, and in which a sheet of paper may be easily dipped.

A still further object of my invention is to procracking. Certain rubber derivatives are among the substances which I so employ.

Preferably, I start, with a particular type glassine paper wherein there has been incorporated during manufacture particular substances to'enhance its desirable physical characteristics.

. A first group of substances so applied may invide a wrapping paper for wrapping bread and other products which has a coating ofa wax compound which is moisture-vapor-proof, but which coating is still not of such excessive thickness a to crack when bent and thereby render the paper opaque.

Yet another object of my invention is to provide a highly plasticized paper for wrapping candyand other products which will retain its twisted condition when used for twisting around pieces of candy and the like.

' In the wrapping of bread and various other food products, and other articles, glassine paper is often used, and the present invention is particularly concerned with such glassine paper. Glassine paper is usually produced by long continued beating of pulp followed by super-calendering, andis highly transparent. Glassine pulp is highly gelatinized.

Ordinary glassine paper usually is given a thin coating of wax which is applied thereto to increase its degree of water-proofness and transparency. However, glassine paper even so treated is not entirely impervious to water vapor, and

creasing the transparency of the paper, leaving a tacky surface, and in hot weather or under elevated temperatures, such a wax coating will run. Further, a thick coating of wax will crack when bent or folded, leaving visible creases.

crease transparency of the paper.

I provide a glassine paper which is treated ,with particular substances which render it substantially moisture-vapor-proof, and at the same time highly plastic. so that it may be bent without elude small percentages of a mild alkali like sodium metasilicate, or cerelose or invert or equivalent special sugar, or both. A second group of substances which may be so applied may include glycerine, glycol, magnesium chloride or zinc chloride; I use relatively more of this second group than of the first group, and ordinarily em. ploy more of the glycerine than the other substances mentioned. A liquid containing one or more of these substances may be applied to the glassine paper' sheet when near the end of its usual proces of manufacture and partially dried,

but still holding a considerable percentage of moisture. The mild alkali tends to increase the sheen. The cerelose improves the transparency, gloss, and moisture-proofness. The glycerine, glycol, magnesium chloride or zinc chloride are hygroscopic, and very considerably increase the pliability and the elasticity in tension; and make the paper highly plasticized.

I take glassine paper preferably of the particular type which has been described, and which has been highly plasticized, and apply thereto-a thin layer of a meltable, waxy substance which .not only renders .the glassine paper moisturevapor-proof, but also imparts desirable heat sealing qualities.

A preferable way to make this waxy composition is to melt some suitable wax such as a good grade of parafiln or beeswax, or the like, and dissolve therein a relatively low percentage of a suitable rubber derivative. Such waxes and the type of rubber derivatives herein described blend satisfactorily in all proportion under such a melting process without a solvent. Preferably, I

On the other hand, a thin coating of wax tends to inuse a high percentage of wax, in order to make the coated paper moisture-vapor-proof.

A rubber derivative suitable for this purpose is the substance known as plio1ite" resin which is a resinous rubber addition product compound of the kind obtained by treating rubber with a compound of the type of hydrated chloro-stannic acid and precipitating the product in a finely divided state which is easily dissolved in wax; similar "pliolite resin derivative are formed by treating rubber with a halide of an amphoteric metal. This type of rubber resin contains about by weight of rubber hydrocarbon, and in the aggre- -.3000. This does not emulaiiy.

about 3% mineral oil, but in some cases m y gate is amber in color. The reaction polymerises the rubber. Such compounds are described, for instance, in the Bruson Patent 1.8486347. It is substances oi this type which I hereafter refer to as "pliolite." I use the unmilled "pliolite" resin in powdered iorm.

This "pliolite" resin blends with the wax in all proportions. I

In one iorm (Formula. A) of my meltable, compound i'or coating the glassine paper, Iadd a small quantity oi a hydrogenated or polymerized odorless fat or oil with a melting point over 130 R, such as hydrogenated cotton-seed oil, as

a lubricant to facilitate handling oi the paper during manufacture. while I have in this tormula indicated 10% hydrogenated cottonseed 011.

this percentage may be increased or diminished within allowable limits according to lubrication conditions to be met. The hydrogenated cottonseed oil employed should be a highly purified grade, tree from objectionable odors. The commercially available product has a melting point oi about 130 F. Instead oi hydrogenated cottonseed oil, I may also employ hydrogenated soybeen all or hydrogenated castor oil.

I also add a small quantity or diamyl naphthalene to improve the adhesive properties of the paper under applied heat.

For certain purposes. I may also add a fewpercent of tricresyl phosphate ("LindoPi which acts as a plasticizer and imparts other desirable qualities.

In an improved modified form or my coating compound. (Formula B), I incorporate substantial quantities of ester gum. and also a heavy. sticky mineral oil. A suitable ester gum is rosin glyceride. A suitable oil is the product furnished by Vacuum Oil 00. under the designation P. O. I usually use use as high as 15% mineral oil. The ester gum prevents wilting or mottling or the glassine paper and makes it more molsture-vapor-prooi. The ester gum also reduces the crystallinlty or the waxy compound and makes it more transparent and harder. The ester gum is too brittle it applied alone without wax.

In the melt described, the ester gum will'precipitate in the absenceoi' the mineral oil which acts as a plasticizer, and hence the ester gum will be oi little use. but in the presence of the plastieizer mineral oil. the ester gum will iorm a part of the melt. The ester gum is preferable to dammar or cumar gums, which I have also tried for this purpose. The wax with incorporated rubber resin, when melted, has still a sumoiently low viscosity so that a sheet or paper may be conveniently dipped therein. This would remain true even it relatively large percentages oi rubber resin were used, but ordinarily, I use only about 5 to of rubber resin.

Besides the uses oi diamyl naphthalene and trlcresyi phosphate as above mentioned, they also serve as plasticisersio prevent the ester gum from drying out or oxidizing out or the solution, and forming on the sides oi the tank or the squeeze rolls.

While ingredients similar to some of those mentioned have been heretoiore used in coating solutions for paper, they have been used in such a way as to require expensive solvents such as toluol and the like to get them into the liquid phase. I avoid theuse'oi these expensive solvents by employing substances which when melted will all pass into the liquid-phase.

One iormula which I have employed with suc- I cessis:

' Formula A Percent 5 "Pliolite" resin (powdered).. l5 Hydrogenated cottonseed oil 10 Diamyl naphthalene 2% Paraiiin wax 83% lo Total 100 Asstated,thewax maybeparaiiimbeeswax. or other vegetable or animal waxes or similar characteristics.

An improved iormula which I have iound more satisfactory in practice ior general application is:

Formula 8 Percent "Pllolite" resin (powdered) 4 n Hydrogenated iat melting above 130' I"...... 5 Dlamyl naphthalene 1 Ester gum 18 Heavy sticky mineral oil 8 Paramn wax 66 Total 100 This improved "Formula. 3." as stated, gives a product much less susceptible to wilting. and which is more moisture-vapor-proor.

The coating according to either "Formula A" or "Formula B" will melt at temperatures of about 175 F. to 200 1'. and liqueiy without the use at any solvent. The melt has a low viscosity.

A iormula which I employ for low temperature or winter conditions is:

Formula C Percent Pliolite" resin (powdered) 6 w Hydrogenated iat melting above 130' IL... 5 Diamyi naphthalene 1 'I'ricresyl phosphate 1 Ester gum ii Heavy sticky mineral oil 8 M Paraflln wax 79 Total 100 For relatively warm temperatures or summer conditions. I had the i'ollowing a desirable ior mule:

Formula D Percent Pliolite" resin (powdered) a Hydrogenated iat melting above 130' P... 15

as Diamyl naphthalene 1 'Iricresyl phosphate 1 Ester gum 15 Heavy sticky mineral oil 8 Parailin wax 59 Total 100 For conditions under which the wrapper must be particularly grease-proof, the iollowing is desirable:

a Formula 8' r P t Plio1ite" resin (powdered) jf e Hydrogenated lat melting above 130 PL..- 40

Dlamyl naphthalene "I 1 ricrcsyl phosphate 2 Ester gum 40 Heavy sticky mineral oil 3 Parailln wax 10 Total In this formula, the 40% of hydrogenated cottonseed oil or other hydrogenated fat imparts grease-proofing qualities.

Under some conditions, as if a particularly good permanent seal is not important, it is possible to omit the "pliolite" resin and get fairly satisfactory results employing the following formula:

Formula F Percent Hydrogenated fat melting above 130 IL--- 40 Diainyl naphthalene 1 Tricresyl phosphate 2 Ester gum 42 Heavy sticky mineral oil -L Paramn wax Total 100 This Formula F will produce a sheet which is heat-sealing, but it does not stay sealed for a length of time as will paper to which the "pliolite" formulas have been applied, but after a few days will unseal. However, Ihave found that sheets treated with Formula F may be made permanently heat-sealing by exuding on to one s :ie of the sheet a concentrated rubber liquid composition, after the sheets have left the squeezerollsafter the coating of Formula F has been applied thereto and is still in melted condition, and before the sheet strikes the congealing rollers.

' A polishing roller smooths the composition on the sides. Also, the melt may be applied. to only one side of the paper by a roller, and to the other side of the paper a'coating of an ordinary wax may be applied.

For application to both sides, four pounds or more of this hot melt is applied to a ream of paper of 480 sheets of size 24 x 36 inches. Best results are obtained when applying about seven pounds of this melt to a ream of paper.

Heretofore, there have been used certain coating compositions having a very large percentage of pliolite" and only a relatively small percentage of wax together with an expensive solvent like toluol; such compositions are necessarily expensive. On'the other hand, I provide a composition with about 66% wax or more and only 4% or 5% pliolite," and'no special solvent, which is much less expensive.

The glassine paper treated with this hot melt is flexible, non-tacky, glossy, and moisture-vapor-resistant, and thermoplastic or adhesive. The treated paper also has increased tensile strength and is more resistant to the action of light and heat than the untreated paper, and is more transparent. The treated paper is tasteless, odorless, and non-toxic. The high degree of imperviousness to moisture-vapor produced makes the product which I have described, particularly suitable for wrappers for bread andother food products. After the treated paper has been wrapped around a food product as bread, it is heat-sealed by momentarilyv applying to overlapping edges by a sealing hot plate, a temperature of about 175 to 200 F. which liquefles the melt including the dispersed plioli and the melted "pliolite on the two surfaces causes them to weld and seal tightly.

I have found the product which I have described to be very satisfactory in application and use. and to have decided advantages over previous compounds intended for similar purposes. I claim:

1. A meltable wax-like composition containing from 4 to 6 percent of a powdered resinous rubber derivative, hydrogenated fat melting above 130 F., and upwards of 59 percent of a wax, said rubber derivative being the resultant of treatin rubber with a halide of an amphoteric metal.

2. A meltable wax-like composition having the formula Per cent Resinous reaction product of rubber andan amphoteric metal halidev compound (powdered) Hydrogenated fat melting above 130 F. 5 'Diamyl naphthalene 1 Tricresyl phosphate 1 Ester gum 5 Heavy sticky mineral oil 3 Paraflln wax '79 Total 100 3. A meltable wax-like-composition having the formula Per cent Resinous reaction product of rubber and an amphoteric metal halide compound (powdered) 6 Hydrogenated fat melting above 130 F 15 Diamyl naphthalene w 1 Tricresyl phosphate 1 Ester gum 15 Heavy sticky mineral oil 3 Paraffin wax 59 Total 4. A meltable wax-like composition having the formula Per cent Resinous reaction product of rubber and an amphoteric metal halide compound (powdered) Hydrogenated fat melting above F 40 Diamyl naphthalene 1 Tricresyl phosphate 2 Ester gum 40 Heavy sticky mineral oil 3 Paramn wax 10 Total 100 sealing means.

6. A wax-like composition for coating papers containing a large percentage of paraffin wax, an

unemulsified heavy mineral oil, .and a low percentage of an unmilled thermoplastic resinous powder prepared by treating rubber with a halide of an amphoterie metal.

7. A wax-like composition for coating papers WILLIAM H. BRYCE.