US2058085A

US2058085A - Sizing paper

Info

Publication number: US2058085A
Application number: US3807A
Authority: US
Inventors: Kress Otto; Charles E Johnson
Original assignee: Paper Chemistry Inst
Current assignee: Institute of Paper Chemistry
Priority date: 1935-01-28
Filing date: 1935-01-28
Publication date: 1936-10-20
Anticipated expiration: 1953-10-20

Description

Patented 'Oct. 20, 1936 Otto mess and Charles E. Johnson, Appleton, Wia, asslgnors to The Institute of Paper Chemistry, Appleton, Win, a corporation of Wiscon- Serial No. 3,307

No Drawing. Application January ca, 1935,

17 Claims. (Cl- 92-21) Our invention relates to the sizing of paper and relates more particularly to sizing with paraflinand the like to produce a paper which is suitable for writing, printing, and the like.

We are aware that paraflin has heretofore been suggested in connection with the sizing of paper and especially in admixture with rosin size. However, when such previously-known sizes are set through the use of acidic material, such as alum. the particles of 'paramn tend to coalesce to form large aggregates which appear in the finished sheets as translucent or semi-translucent "wax spots and which also offer trouble in the papermaking operation by forming .parafiln spots on the wire, thus interfering with the operation of the paper machine. While this difficulty may be reduced by the use of very small quantities of parail'in, such procedure eliminates the advantage of sizing with parafiin which may be obtained l when larger quantities arefused. An object of our invention is to devise a method & whereby large quantities of paraifin may be used for sizing while avoiding the disadvantages above referred to.

Another object of Tour invention is to provide, as a new composition of matter, a highly stable emulsion-of paraflin or thelike suitable .for sizing.

We have found that paraflin may be placed in a stable, finely-divided form suitable for sizing by emulsifying it with an emulsifying agent such.

as a soluble soap, the emulsion being stabilized by a protein material such as, for example, milk casein or soy bean casein; Such an emulsion is highly stable even though the parafiln may be present in quantities up to 75 per cent or more of the solids present in the mixture; the paraflin will not agglomerate upon heating or as a result 3 of the hydrolytic action of water, the action of alkaline-earth fillers, or any other agents commonly used in paper making. x

. According to our invention, the emulsion is broken by addition of an acidic substance, such as alum, resulting in-i-setting the paraffin on the fiber in finelydivided-form, each particle being surrounded by a film of protein material.

- While we do not wish to limit ourselves to any particularitheory of reaction, we believe that the protein which is present in the emulsion, when said emulsion is set by addition of acidic mateso rial, surrounds in a molecular film the minute particles of paraflln, thus preventing coalescence thereof into larger particles. We have noted, also, that amixture of parafiin emulsion and alkaline earth filler, wherein the emulsion has been broken by alum, does notshow the presence of a parailln film or of particles of parafiin which is visible to the naked eye, even upon boiling and Y subsequent cooling. Our tests indicate thatthe paraflln is deposited on the fiber in sub-microscopic particles coated with protein, whereby said 5 particles cannot agglomerate and are not readily removable from the fiber.

Example This example is given as merely illustrative of 10 our invention and not as limiting.

The following is a preferred way in which we prepare the paraflln emulsion. Ten parts by red oil, gums like gum arable, sodium stearate,

etc. To this mixtureAO parts of molten parafiin 20 are slowly run in under agitation. The paraffin which we have been using represents normal paraflin of a melting point of 124 F. but higher melting point paraffin might be used or lower melting point paraifin, even down to ordinary oils. 25

The mixture of casein, emulsifier, and parailin is stirred with a high speed stirrer or other suitable equipment. The time of mixing is usually approximately 15 minutes, the mixture then being diluted with about 1000 parts of water at ap- 30 proximately C. These temperatures can be adjusted, depending upon the melting point. of the paraflin used. The emulsion can likewise be made through the use of a colloid mill or other suitable equipment.

The preferred way in which this -'casein-parailin size is used is to add it to the pulp in the beaten and then set the size through the use of alum in the usual manner to give an-aeidlty of from about pH 4.5 to- 6.0. After about five minutes, which 40 will ordinarily be sufilcient time for the setting of the size, the calcium carbonate or other alkaline earth filler may beintroduced in slurry form at a concentration of about two pounds per gallon, if such. filler is desired. The usual treat- 5 ments which are given to pulp in the beater, such as coloring or the possible addition of starch, may also be practiced, if desired. In case it. is desired to use some rosin size in conjunction with the special casein-paraffin size, then both types of so a size may be added to the pulp and set with alum in the usual manner.

In using the special casein-paraffin size along with an alkaline-earth filler, in which case the whltewaters will be alkaline, the heaters should 66 be made up with fresh water at the normal concentration of beater stock, say, from 4 to 6 per cent. However, the diluting water for the dropping of the beaters may be white water if it is available, and thickened stock such as might be recovered from the usual white water systems may be added just prior to dropping. In case no filler is used or in case any fillers other than alkaline-earth fillers are used, such as ordinary clay, no precautions need be taken with regard to the use of white water, and it may be used to make up the beaters or may be omitted as desired. Wet and dry broke should be handled separately in a broke heater and proportionately dropped to the beater chest, or it may be added in slush form to the beater after the sizing operation.

A typical example for the production of book paper would be about as follows:

Pounds Bleached soda pulp 500 Bleached sulphite pulp 500 To this pulp is added about 5 per cent by dry weight of the casein-paraffin size, which is then set with alum, as described. To this mixture may be added 300 pounds of alkaline-earth filler, the whole beater having been made up with fresh water but using any excess white water which may be available during the operation of dropping the beater.

The stock from the beater is handled in the usual manner over the paper machine. The mix will be on the alkaline side, in view of the excess of alkaline earth filler, with a pH higher than 7.0, and the sizing in the finished sheet will have been accomplished entirely through the use of paramn in such a finely divided state that there will be no danger of having parafiln spots in the finished paper or of operating troubles resulting from parailin spots on the wire of the paper machine.

It will be understood that other acid-reacting materials may be used to set the size, although alum is preferred. Also, while we have described the use of alkaline filler, it is understood that our invention is not restricted to this featurevarious other types of filler may be used, if desired.

Various modifications and variations coming within the spirit of our invention will doubtless suggest themselves to those skilled in the art. Hence, we do not wish to be limited to the specific embodiments and details herein disclosed except to the extent indicated by the appended claims, which are to be interpreted as broadly as the state of the art will permit.

The term casein as used in the claims includes both milk casein and soya bean casein.

We claim as our invention:

1. The method of sizing paper comprising introducing into a furnish an aqueous colloidal dispersion of waxy material stabilized with an acid precipitable water-insoluble protein, the latter being present in such a quantity relative to the waxy material that particles thereof deposited on the paper fiber of the furnish are surrounded by a protein film preventing agglomeration of the waxy particles, and adding to the furnish acidic material to precipitate the waxy and protein particles on the fiber with the protein material coating the waxy particles.

2. The method of sizing paper comprising introducing into a furnish an aqueous colloidal dispersion of waxy material stabilized with an alkali soluble water-insoluble protein precipitable from furnish acidic material to precipitate the waxy and protein particles on the fiber with the protein material coating the waxy particles.

'3. The method of sizing paper comprising introducing into a furnish an aqueous colloidal dispersion of waxy material stabilized with an acid precipitable water-insoluble protein, the latter being present in such a quantity relative to the waxy material that particles thereof deposited on the paper fiber of the furnish are surrounded by a protein film preventing agglomeration of the waxy particles, and adding to the furnish alum to precipitate the waxy and protein particles on the fiber with the protein material coating the waxy particles.

4. The method of sizing paper comprising introducing into a furnish an aqueous colloidal dispersion of waxy material stabilized with an alkali soluble water-insoluble protein precipitable from an alkali solution by an acidic material, said protein being present in such a quantity relative to the waxy material that the particles thereof deposited on the paper fiber of the furnish are surrounded by a protein film preventing agglomeration of the waxy particles, and adding to the furnish alum to precipitate the waxy and protein particles on the fiber with the protein material coating the waxy particles.

5. The method of sizing paper comprising introducing into a furnish an aqueous colloidal dispersion of waxy material stabilized with an acid precipitable water-insoluble protein, the latter being present'in such a quantity relative to the waxy material that particles thereof deposited on the paper fiber of the furnish are surrounded by a protein film preventing agglomeration of the waxy particles, adding to the furnish acidic material to precipitate the waxy and protein particles on the fiber with the protein material coating the waxy particles, and then adding to the furnish an alkaline earth filler.

6. The method of sizing paper comprising introducing into a furnish an aqueous colloidal dispersion of waxy material stabilized with an alkali solublei water-insoluble protein precipitable from an alkali solution by an acidicmaterial, said protein being present in such a quantity relative to the waxy material that the particles thereof deposited on the paper fiber of the furnish are surrounded by a protein film preventing agglomeration of the waxy particles, adding to the furnish acidic material to precipitate the waxy and protein particles on the fiber with the protein material coating the waxy particles, and then adding to the furnish an alkaline earth filler.

7. The method of sizing paper comprising introducing into a furnish an aqueous colloidal dispersion of waxy material stabilized with an acid precipitable water-insoluble protein, the latter being present in such a quantity relative to the waxy material that particles thereof deposited on the paper fiber of the furnish are surrounded by a protein film preventing agglomeration of the waxy particles, adding to the furnish alum to precipitate the waxy and protein particles on the fiber with the protein material coating the waxy particles, and then adding to the furnish an alkaline earth filler.

' troducing into a furnish an aqueous colloidal ticles thereof venting latter .being present in such dispersion of waxy material, stabilized with an alkali soluble water-insoluble protein precipitable from alkali ,solution by an acidic material, said protein being present in such a quantity relative to the waxy material that the pardeposited on the paper fiber of the furnish are surrounded by a protein film pre- ,agglomeration of the waxy adding to the iumish alum to precipitate the waxy and protein particles on the fiber with the protein material coating the waxy particles, and

'15 then adding to the furnish an alkaline earth filler.

9. The method of sizing paper comprisingproviding a furnish having present an aqueous colloidal dispersion of a mixture of rosin size and waxy material, the latterbeing stabilized: with an acid precipitable water-insoluble protein, the a quantity relativeto, the waxy material that particles thereofdeposited on the paper fiber of the furnish are surrounded by a protein film, preventing agglomeration of the waxy particles, and adding to the furnish acidic material to precipitate the waxy and protein particles on the fiber with the protein material coating the waxy particles.

10. The method of sizing-paper comprising providing a furnish having present an aqueous colloidal dispersion of, a mixture of rosin size and waxy material, the latter being stabilized with an alkali soluble water-insoluble protein precipitable from an alkali solution by an acidic material, said protein being present in such a quantity relative tothe waxy material that particles thereof "deposited on the paper fiber of the i 'urnish are surrounded by a protein film preventing agglomeration of the waxy. particles, and adding to the furnish acidic material to precipitate the waxy and protein particles on the fiber with the protein material coating the waxy particles.

o tein, the 'latter being present 11. m method or sizing aper comprising providing a furnish having present and waxy material, the latter being stabilized withan acid precipitable water-insoluble prorelative to the waxy material that particles thereof deposited on the paper nish are surrounded by a protein film preventing agglomeration of the waxy particles, and adding to the furnish alum to precipitate the waxy and protein particles on the fiber with the'protein material coating the waxy particles.

12. The method of sizing paper comprising providing a furnish having present an aqueous colloidal dispersion of a mixture of rosin size and waxy material, ,the latter'being stabilized with a an alkali soluble water-insoluble protein precipitable from an alkali solution by an acidic material, said protein being present in such a quan-.

tity relative to the waxy material that particles thereof deposited on the paper fiber of the furnish are surrounded by a ing agglomeration of the waxy particles,and adding to the furnish alum to precipitate the waxy and protein particles on the fiber with the protein material coating the waxy. particles.

13. The method of sizing papercomprising provlding a furnish having present an aqueous colparticles,

particles on the an aqueous. colloidal dispersion of a mixture of rosin size in such a quantity fiber of the fur-' tein selected from protein film preventvlding a furnish having present an aqueous colloidal dispersion of a mixture of rosin size and waxy'material t-he latter being stabilized with an alkali soluble water-insoluble protein precipitable from an alkali solution by an acidic material, said protein being present in such a quantity relative to the waxy material that particles there of deposited on the paper fiber of the furnish 14. The method of sizing paper comprising proare surrounded by a protein film preventing agglomeration of the waxy particles, adding to the furnish acidic material to precipitate the waxy and protein particles on the fiber with the protein material coating the waxy particles, and

adding to the so-treated'furnish an alkaline earth '15. The method of sizing paper comprising provlding a furnish having present an aqueous colloidal dispersion waxy material, the latter being stabilized with an acid precipitable water-insoluble protein, the latter being present in such. aquantity relative to the waxy material that particles thereof deposited on the paper fiber of the furnish are surrounded by "a protein film preventing agglomeration of the waxy particles, adding to the furnish alum to precipitate the waxy'andprotein fiber with the protein material coating the waxy particles, and adding to the sotreated furnish an alkaline earth filler.

, 16. The method of sizing paper comprising pro-- vlding a furnish having p resent an' aqueous colloidal dispersion of a mixture of rosin size and waxy material, the latter being stabilized with an alkali soluble water-insoluble protein precipitable from an alkali solution by an acidic material, said protein being present in such a quantity relative to the waxy material that particles thereof deposited on the paper fiber of the furnish are surrounded by a protein film preventing agglom eration of the waxy particles, adding to the furnish alum to precipitate the waxy and protein particles in the fiber with the protein material coating the waxy particles, so-treated furnish an alkaline earth filler.

17. The method 01" sizing paper comprising inof a. mixture. of rosin size and and adding to'the troducing into aiurnish an aqueous colloidal diswaxy material stabilized with a prothe group consisting of milk casein, said protein being persion of a casein and soya bean present in such aquantity relative to the waxy material-that particles thereof deposited on-the -paper fiber. of the'furnish is surrounded by a protein film' preventing agglomeration of the waxy particles, and adding to the furnish acidic material to precipitate the wax and protein particles onthe fiber with the protein material coating the waxy particles.

' O'I'IO KRESS.

CHARLES E. J OHNSDN.