US2341302A - Method of handling rosin size - Google Patents

Description

?atenied Feb. 8, 1944 METHOD OF HANDLING ROSIN SIZE Ernest S. Wilson, Wilmington, Del., assignor to Hercules Powder Company, Wilmington, Del., a corporation of Delaware No Drawing. Application November 18, 1939, Serial No. 305,167

2 Claims. (Cl. 214-452) This invention relates to rosin size and more particularly to a method of handling rosin size.

Rosin size comprising a mixture of free rosin and saponified rosin is used in large quantities in the manufacture of paper and the like. Usually the size is prepared at a chemical plant and is then shipped to the paper mill in the form of a paste, which may be packed in barrels, drums or tank cars. For example, a paste size which is sold and used extensively, comprises about 70% solids and about 30% water, which means that 43% of the freight (based on the solids content) or other shipping charges are paid for the water. This expense is'objectionable, particularly where the chemical plant and the paper mill are a considerable distanc apart and the cost offreight becomes an important item.

The dry forms of size and particularly the type formed by-spraying, are open to substantial objection in that they tend to oxidize in the presence of air. Where some free rosin is contained in the size, there is a greater tendency for the size to oxidize. Oxidation, and subsequent heating of dry size, is deleterious to the size, and generally undesirable where it is to be stored for any length of time, or to be shipped over any considerable distance. The low bulk density of such dried sizes may be objectionable from a handling and transportation angle, and is probably partially responsible for its tendency to oxidize rapidly due to the air present between siz'e particles.

In spite of the above objections. dry size mixtures are common today. A dry size mixture may be prepared by spraying ground cold rosin with a refrigerated caustic soda solution. This procedure is complicated and results in further difl'iculties. Presence of free caustic requires special receptacles, such as rubber bags, which increases the cost of packing and shipping the mixture. The presence of free caustic makes the size dangerous to handle; Also the resultant material has to be added to water and boiled at the paper mill to complete the reaction.

Another common method of manufacturing dry size is to incorporate'in the .slze materials acting as anti-oxidants. (The quantity of material required to check efiectively oxidation greatly increases the. cost of the size. .Also the additional treating operation requires additional equipment and complicates the manufacture of the size.

An object of the invention is to provide an improved method of handling rosin size.

Another object is to prevent decomposition or darkening of dried rosin size during shipment or storage thereof, without the use of antioxidants.

Another object is to provide a method of shipping dried rosin.size in large quantities, for example, in tank cars, without danger of decomposition br oxidation thereof.

A further and more specific object is to pro-' vide a method of shipping a higli free rosin dry size which can be conveniently handled and shipped, and, upon reaching its destination, can be readily converted into a paste size by adtmg water thereto.

.A still further object is to accomplish the .iore- .going objects without employing additional operations, treatment with anti-oxidants, or the use of special expensive containers such as rubber bags.

Other and further objects will be obvious upon an understanding of the illustrative embodiment about to be described, or will be indicated in the appended claims, and various advantages not referred to herein will-occur to one skilled in the art upon employment of the invention in practice.

These objects generally are accomplished by drying a paste size, placing the size in a suitable receptacle containing a minimum amount of air, and if desired reducing. the free oxygen content or free oxygen concentration of the air in the receptacle, and then substantially hermetically sealing. the receptacle. When size is received by the paper manufacturer and it is desired to use the size, water is added thereto, whereby the size is converted back to a paste size which can be readily used for making size emu1sions.

In accordance with the invention, a rosin size paste comprising a mixture of free rosin and saponifled rosin and other materials adapted to assist emulsincation or dispersion of the size may be prepared in any well-known or desired manner. The paste, when dried results in a rosin size which may contain between about 2 and 40% free rosin on a dry basis, but may in some cases have a higher free rosin content. The drying may be performed'in any suitable man nor, for example, by desiccating the paste size to provide a dried rosin size in the form of a dense powder, flakes, chips, pellets, wafers, or small briquettes, or the like.

The dried rosin size is then placed in an airtight container or receptacle.ofanysuitableshape or capacity, for example, a metal drum or railway tank car. Preferably, the container is completely filled with size to displace as much air as is possible and the lid, cover, or manhole cover, as in the case of a tank car, is attached.

in a manner to substantially hermetically seal the container. The air present will be insufiicient to cause oxidation or decomposition and by use of a hermetic seal, additional air is kept out of contact with the size.

This method is particularly adapted for shipping dried size in tank cars. For example, it has been found that a tank car can be substantially completely filled with a granulated dry rosin size so that, at 30 C. and atmospheric pressure, less than 0.015% by weight of oxygen based on weight of size is present. This oxygen content of the air present will not appreciably oxidize the size, and if additional air is prevented from contacting the size by hermetically sealing the tank car, no further oxidation can take place.

In some cases, an amount of air may be trapped between the particles of the size. This air may be exhausted from the container by means of a suction pump or other vacuumizing device which may be suitably connected to a bung or port of the container. A complete vacuum, although desirable, is not necessary because good results can be attained where suincient air has been exhausted from the container to reduce the internal pressure to about between 4 and pounds per square inch, absolute. By withdrawing a volume of air, the free oxygen in contact with the size is reduced, and darkening, decomposition, deterioration, or oxidation of the size is prevented, even if the containers are stored in warm places or subjected to the heat of the sun.

After the desired volume of air has been re-.

.the container may be provided with a valve associated with the bung or port, which is adapted to be kept open while exhausting the air and adapted to be closed prior to disconnecting the suction device from the bung or port.

A modified method of reducing the free oxygen in the container, comprises attaching a gasifying device to the port or bung and introducing an inert gas which displaces substantially. all or at least a portion of the air in the container, prior to introducing th dry size into the container, or, if desired, the size may be introduced first and the air in the container may be displaced by inert gas. Preferably, nitrogen is employed because of its inertness. The reduction of the oxygen concentration lessens the likelihood of rapid oxidation which may ultimately cause spontaneouscombustion and the inert gas in contact with the size prevents decomposition thereof. In place of nitrogen, carbon dioxide may be used, but preferably in small quantities so that the size is not materially carbonated or desaponified.

After the containers are packed and sealed, they may be stored at the chemical plant, shipped in any suitable manner and thereafter stored at the paper mill without danger of spoilage of the driedsize. 'When the. size is to be used, it maybe removed from the containers in any suitable manner.

A preferred method of removing the size, for example, from tank cars, comprises adding a quantity of water to the size, while in the tank car, to provide a paste containing between about 50 and 75% solids, but preferably between about 60 and 70% solids. The resulting paste is of a type which can then be readily emulsified for use in the manufacture oi paper products. The mixture of size and water may be agitated to insure thorough mixing by mechanical stirring devices or by circulating the water through the size. A pipe line ma then be attached to the tank car for conveyin the paste to the emulsifying or storage tanks in the paper mill, either by gravity flow or by pumping. This improved method of removal eliminates the use of special equipment for conveying dry materials or the use of manual labor which otherwise would befor converting dry size into paste size. Also, the

size is dissolved beforeit has a chance to come in contact with any large quantity of oxygencontaining air.

From the foregoing description, it will be seen I that the present invention provides an improved method of packing, shipping, storing, and handling dried rosin size. The size can be conveniently placed in tank cars, the air content of the tank can be reduced and the tank can be sealed in a simple, expeditious manner. Upon arrival at the paper mill, the size can be readily removed. During storage or shipment, there is no danger of darkening or decomposition. .Furthermore, dry size can be shipped safely without the use of special receptacles or anti-oxidants. By employing the present method, dried rosin size can be shipped in large quantities, .for example, in tank cars in a safe and inexpensive manner.

It will be understood that the details and examples hereinbefore set forth are illustrative only and that the invention as broadly described and claimed is in no way limited thereby.

What I claim and desire to protect by Letters Patent is:

1. The method of handling saponiiied rosin size which comprises desiccating a paste-type size to form a dry substantially free-flowing powder, said powder consisting of the solid ingredients of said paste size, placing said powder in a railway tank car which has been filled with an inert gas, substantially hermetically sealing the tank car to prevent ingress of air during shipment, shipping the tank car to the vicinity of the point at which the size is to be used, opening the tank car, adding with agitation a quantity of water sufflcient to reconstitute the paste size to. its original form, and piping the paste size so formed from the tank car,

2. The method of handling saponifled rosin size which comprises desiccating a paste-type size, which contains between 2.5 and about 40% by weight 01' free rosin, to form a dry substantially free-flowing powder, said powder consisting of the solid ingredients of said paste size, placing said powder in a railway tank car which has been filled with an inert gas, substantially hermetically sealing the tank car to prevent ingress of air during shipment, shipping the tank car to the vicinity of the point at which the size is' ERNEST S. WILSON.