US1607517A - Process of paper making - Google Patents

Description

Patented1o,1926. UNITED STATES 1,607,517 PATENT OFFICE.-

CARLETON ELLIS, OF MONTCLAIR, NEW JERSEY, ASSIGNOB TO ELLIS-FOSTER COM- run,

A CORPORATION OF NEW JERSEY.

PROCESS OF PAPER MAKING.

No Drawing.

This invention relates to the process of waterproofing paper, the object being to introduce awat'erproofing dispersion, which will be absorbed readily, and is of particu- 5 lar value in the production of various papers, and-especially for the production of transparent, translucent and waterproof papers.

Waterproof paper 1H either by treatment resulting in a modification of the fibres composing the paper, or by the incorporation of a material with the fibres, which results in-the production of a waterproof product. My invention applies to the production of transparent or translucent and waterproof paper, by incorporation of certain materials, which fill the interstices and afford the transparent or translucent and waterproof effects desired. The

present practice is that of preparing a sheet of paper, immersing it in amolten bath of wax, oil or resin. In some ca es, the emulsions containing waxes have been incorporated with the pulp prior to paper manufacture. In general, considerable difliculty has been experienced in secilring proper absorption and dispersion.

In carrying out my invention I prepare an emulsion of the wax, or mixtures thereof with oils, resins, starches, and the like, employing water as a vehicle, and preferably using @a colloid mill to convert the waterproofing agent into a state of extreme fineness or dispersion. It is advantageous,-but not essentially necessary to previously dissolve in the water a small amount of a soluble soap, such as sodium, potassium or ammonium stearate, palmitate, resinate, and the like. In other cases, a small amount of an alkaline salt such as sodium phosphate, soda ash, or of an alkali, such as caustic soda or potash, may be employed instead of the soap. The use of such salts is particularly desirable when free rosin or fatty acids have been added to'the mixture Having prepared the emulsion by means of a powerful emulsifying means such' as the aforesaid colloid mill; I introduce said emulsion into the beater with the pulp. find it highly desirable to add the emulsion to the pulp substantially at the beginning of the beating operation, as this accomplishes a very much better dispersionand absorption than by adding the emulsion at a later stage. The dispersion is rapidly absorbed ordinarily is producedgenerally -heat the pulp with Application filed April 8, 1926. Serial No. 100,719.

by the fibres (the speed and extent of absorption depending to a large extent on the proportion of hydrocellulose present) and aftersuflicient time has elapsed, the sheet is formed in the usual manner.

In order to obtain the maximum amount of absorption, I find it highly desirable to add the wax dispersion to the pulp in the beater at a temperature substantially above the melting point of the wax employed. In most cases the temperature of boiling water is about right, although temperatures as low as 90 C. are in some cases suitable.

Such waxes as paraflin, Montan, ceresin, carnauba, japan, beeswax, etc., are suitable for the purpose of my invention, although in most cases I employ paraffin, particularly on account of its low cost.

In order to obtain the maximum absorption I have found that it is necessary to use a pulp containing a substantial amount of hydrocellulose. While hydrocellulose may be formed by a very prolonged action of pulp in the beater engine, I find it more economical, in most cases, to accelerate the 0 formation of hydrocellulose by means of acid hydrolysis. In general, it is desirable to conduct this acid hydrolysis separately and previous to the introduction of "the wax ispersion, although, in some cases, the acid hydrolysis may be employed in the beater simultaneously with the incorporation of the wax emulsion.- Since the various acids and salts which may be employed for this treatment are rather corrosive, it is, however, more preferable'to treat the pulp previous to the treatment in the beater. In order to accelerate the formation of hydrocellulose, I may add to the pulp such substances as sulphuric, hydrochloric, phosphoric and oxalic acids, or acid salts such as sodium or potassium bisulphates, zinc chloride, and such other salts as potassium iodide, calcium thiocyanide and various other salts which are found to accelerate the formation or pro duction of hydrocellulose. These substances exert the most pronounced efli'ect when used at an elevated temperature, i. e., over C. and it is usually necessary to the concentrated salt solutions above 80 C. for proper modification of the fibres with formation of hydrocellulose. Stronger chemicals such as sulphuric acid when used usually require no heating.

- As an illustrationImay dissolve approxiof water,

mately 4 lbs. of sodium stearate in 12 gallons the latter preferably hot. This so lution is heated to a temperature somewhat above the meltin point of the wax vemployed. Preferab y I use-paraflin wax and heat the soap solution to about 90 C. adding thereto 100 lbs; of the wax. At a temperature of 90 C. I introduce the mixture of melted wax and stearate solution into a colloid mill, thereby bringing about a high degree of emulsification, and, in some cases, what may be termed homogenization. Approximately 200 lbs. of emulsion is obtained, which is suflicient to treat about 700 lbs. of paper or paper stock. a This emulsion is added to the pulp, which preferably has been previously treated, so as to furnish a substantial amount of hydrocellulose, in the beater engine, and the amount of time necessary for the treatment will depend upon the type of paper to be produced, ranging from approximately three to -fortyeight hours.

There are several ways in which I may treat the paper or paper pulp to accelerate the formation of hydrocellulose, but in the preferred form I use sulphuric acid of s ecific gravity of approximately 1.52 and treat the pulp with this acid for several hours at room temperature, then neutralize and wash, whereby hydrocellulose is formed in substantial amount. Various other acids or salts may be used in lieu of this treatment, as previously described.

In order to produce a more flexible waterproof paper suitable for the manufacture of milk bottle caps and waterproof papers suitable for use on food containers, I prefer to use a wax dispersion containing a substantial amount of a colorless paraffin oil, such as is known to the trade as Marcol and whose and . preferred for the boiling point is substantially over 200 C. specific gravity 850 at 17 C. The use of this oil confers added flexibility upon the waterproof product and is therefore highly advantageous especially where product is to be drawn through dies. In certain cases various other petroleum oils may be used, although the pure, almost medicinal grade of oil, known to the trade as Marcol is to be production of waterproof papers which are to be used on food containers.

What I'claim is p 1. In the process-of paper making, the step which consists in the addition of a hot aqueous wax dispersion to a pulp containing hydrocellulose.

2. A process for making waterproof pa-' per, which consists in the addition of an aqueous wax dispersion to a pulp containing hydrocellulose, in a beater engine, at an elevated temperature.

3. A process for making waterproof pa- 1 per, which consists in the addition of an aqueous wax dispersion to a pulp containing hydrocellulose, in a beater engine, at a temperature above the melting 4. A process for making waterproof paper, which consists in the addition of an aqueous wax dispersion to a pulp containing hydrocellulose, in a beater engine, at a temperature of approximately to C.

5. A process of making waterproof pa ,er suitable for use with food products, whlch consists in the addition of an aqueous wax dispersion containing a petroleum hydrocarbon oil, to a pulp containing hydrocellulose, in a heater engine, at an elevated temperature.

CARLETON ELLIS.

point of the wax.