US2785067A

US2785067A - Beater sizing of paper with ketene dimers

Info

Publication number: US2785067A
Application number: US423521A
Authority: US
Inventors: Jr Wilfred E Osberg
Original assignee: Hercules Powder Co
Current assignee: Hercules Powder Co
Priority date: 1954-04-15
Filing date: 1954-04-15
Publication date: 1957-03-12
Anticipated expiration: 1974-03-12
Also published as: GB765715A

Description

United States Patent BEATER SIZING OF PAPER WITH KETENE DIMERS Wilfred E. Osberg, Jr., Newport, Del., assignor to Hercules Powder Company, Wilmington, DeL, a corporation of Delaware No Drawing. Application April 15, 1954, Serial No. 423,521

8 Claims. (Cl. 92-21) This invention relates to a process of beater sizing paper with higher organic ketene dimers.

In the sizing of paper it is conventional to add a sizing agent, such as, usually, rosin size, and, occasionally, wax,

asphaltic material, or the like to the pulp slurry before the sheet is formed. These sizing materials are precipitated on the pulp by the addition of papermakers alum which is added to the pulp slurry to bring the pH to'4 to 4.5. This is termed the beater sizing process. The bulk of sized paper prepared in this country is beater sized. A much smaller amount of paper is sized by applying a sizing agent to the surface of the paper sheet.

Recently, in U. S. Patent 2,627,477 to William Downey, it is disclosed that ketene dimer emulsions are useful in the surface sizing of paper. The emulsions are not substantive to the cellulose fibers so that heretofore it has not been practical to use these emulsions in beater sizing.

There has now been discovered apracticable process whereby aqueous emulsions of ketene dimers, as described in the said patent to Downey, may be used in a heater sizing process. In this process ketene dimer emulsions are added to the beater at a concentration of from about parts of ketene dimer per million parts of water to about 200 parts of ketene dimer per million parts of 7 water, and the pH of the pulp slurry is adjusted to within the range of 5 to 9, inclusive. The pulp is then formed into a sheet and dried. If desired, the sheet may be cured by heating to a relatively elevated temperature, say about 100 C., for a short period of time such as about 10 minutes. However, this is not necessary as adequate sizing develops on mere standing at room temperature for a few hours. Furthermore, if the sheet is prepared at a relatively high pH, such as about 8.5 or higher, a sheet will be sized as it comes oif the machine so that additional curing is not needed.

This process has several advantages. Thus, it has been found that even though the emulsions are not naturally substantive to cellulose they are retained by the cellulose fibers in much greater amounts than their concentration in the water would indicate. Further, at the low concentrations used in the process of the instant invention, the amounts lost in the discarded white water are very small. While the ketene dimer emulsions can be used at the pHs normally used in paper manufacture, it has been found that the use of the critical pH range reduces almost in half the amount of ketene dimer needed to obtain a given degree of sizing.

The aqueous emulsions when used in this process are stable over the entire pH range of the process and are even stable when subjected to the vigorous mechanical action found in the beater. The discovery that the ketene dimer emulsions are stable under these extreme conditions is truly unusual and surprising. Further, the process of the instant invention obviates the necessity of using alum to fix the size on the paper fibers. The aqueous emulsions of ketene dimers do not cause foam in the papermaking system, thereby permitting faster machine speeds in those systems where foam is the limiting factor. The process of the instant invention, in permitting the 2,785,067 Patented Mar. 12, 1957 use of slightly acid and alkaline pHs in the paper system, gives greatly improved initial strength to the sheet as well as improved permanence.

The ketene dimers which are used in the instant process are dimers having the formula ERCH=C=O12 where R is a hydrocarbon radical, such as alkyl having at least 8 carbon atoms, cycloalkyl having at least 6 carbon atoms, aryl, aralkyl, and alkaryl. In naming ketene dimers, the radical R is named followed by ketene dimer. Thus, phenyl ketene dimer is:

benzyl ketene dimer is:

and decyl ketene dimer is: [C1oH21-CH=C=O]2. Representative ketene dimers whose emulsions may be used in the process of the instant invention include octyl, decyl, dodecyl, tetradecyl, hexadecyl, octadecyl, eicosyl, docosyl, tetracosyl, phenyl, benzyl B-naphthyl and cyclohexyl ketene dimers, as well as the ketene dimers prepared from montanic acid, naphthenic acid, A decylenic acid, n -dodecylenic acid, palmitoleic acid, oleic acid, ricinoleic acid, petroselinic acid, vaccenic acid, linoleic acid, linolenic acid, eleostearic acid, licanic acid, parinaric acid, tariric acid, gadoleic acid, arachidonic acid, cetoleic acid, erucic acid and selacholeic acid, as well as ketene dimers prepared from naturally occurring mixtures of fatty acids, such as those mixtures found in coconut oil, babassu oil, palrn kernel oil, palm oil, olive oil, peanut oil, rape oil, beef tallow, lard (leaf) and Whale blubber. Mixtures of any of the above-named fatty acids with each other may also be used. Thus, a mixture of stearic and oleic acids gives a ketene dimer which is very easily emulsified. A mixture which is particularly preferred is the mixed tetradecy1-, hexadecyl ketene dimer prepared from a mixture of stearic acid and palmitic acid, particularly a mixture of these two acids in approximately equal proportions. The emulsions used in this process are prepared as set forth in the said patent to William Downey.

When there is 0.1% hexadecyl ketene dimerin the paper, based on the dry weight of the paper, only one hydroxyl group in about every nine thousand-present in the cellulose is reacted with the ketene dimer. No method is known by which such minuscule amounts of ketene dimer can be determined quantitatively in the presence of such a large amount of cellulose. Accordingly, the amount of ketene dimer on the paper 'was determined mathematically in Examples 1-11. This method is as follows: The conditions of preparation are kept constant. Thus, a Noble and Wood handsheet machine is used; A given amount of water was added to the deckle box and to this was added a given amount of ketene dimer emulsion. Wet 2:1 water to pulp sheets were added to the deckle box and the squeezings from the squeeze'rolls were caught and poured back to the deckle box to keep the amount of water constant. The percent of the ketene dimer present in the water which is abstracted by the.

. that the diluted paper pulp is treated with X grams or ketene dimer, and assume further that the amount of ketene dimer retained on each sheet formed is Y% of that present in the water, then the first sheet prepared will contain X times Y grams of ketene dimer, the second sheet will contain (X-XY)Y grams of ketene dimer,

Knowing the concentration of dimer in the solution, the amount on the sheet was easily calculated.

Table III Percent of Dimer in Paper Sizing Obtained Based on Dry Weight of Paper Ketene Dimer Example Poor, splotchy. No sizing. Poor sizing.

Fair sizing.

Excellent.

Very good. Do. Do.

Excellent.

. Good.

. Fair. 0. 051 Excellent.

-do Ketene dimer prepared from montanic acid. Ketene dimer prepared from montanic acid.

The above data clearly show that for maximum efiectiveness in sizing with an alkyl ketene dimer, only octyl and higher alkyl ketene dimers should be used. The data also clearly show that aralkyl and aryl ketene dimers are effective in sizing paper.

EXAMPLE 29 A ketene dimer emulsion was prepared by blending 100 parts of 85% active hexadecyl ketene dimer with parts of xylene, 20 parts of methyl oleate and 20 parts of polyoxyethylene sorbitol laurate sold by the Atlas Powder Company under the trade name Atlox 1045. This mixture was then melted at 70 C. and water (also at 70 C.) added thereto slowly while the mixture was stirred. This formed a water-in-oil emulsion which at about 50% total solids inverted to give an oil-in-water emulsion. Addition of water was continued until the solids were about 40% whereupon the emulsion was dumped into hot water to give an emulsion having about 1.5% solids.

Six beaters were furnished with 2200 lb. each of unbleached kraft pulp at 7% consistency. The pulp was beaten and 2.7 lb. of ketene dimer solids added to each beater together with additional water to give a pulp slurry of 4% consistency. There was thus present in the water 0.005% ketene dimer based on the water. A closed system was used and a small additional amount of the ketene dimer emulsion was added to the white water so that the concentration of ketene dimer at the wire was maintained at about 0.005% ketene dimer based on the water. The pulp was diluted with the treated white water and run out on a Fourdrinier paper machine in the usual manner. The pH of the white water was varied by adding caustic. Substantial quantities of paper were made with the pH of the white water at 6.7-7.0, 8.5, and 9.6.

The reels were stored overnight at room temperature. The paper prepared at approximately neutral pHs was not appreciably sized as it came off the machine, while that paper prepared at pHs or" 8.5 and 9.6 was sized as it came off the machine. Within about two hours of storage at room temperature, sizing developed in all sheets, and by the morning after the run, all sheets were similarly hard-sized. Although agitation was quite vigorous in all of the machine chests, the amount of foam in the pulp was negligible. There was also a negligible amount of foam on the wire although the machine was run at 570 ft./min. The paper had a basis weight of lb. per ream and was Yankee dried. It was well sized and on specification in every respect.

6 EXAMPLE so In another run a 50-lb. unbleached kraft sheet was made on a Fourdrinier machine. The hexadecyl ketene dimer emulsion was prepared as in Example 29. In contrast to Example 29, the emulsion was added continuously to the stock just before the fan pump, additions being made with both 5 and 7 lb. of the dimer per ton of airdried stock. The pH of the system throughout the run was about 8.4. The concentration of ketene dimer at the wire was about 10 parts per million parts of water for the one run and about 14 parts of ketene dimer per million parts of water in the other run. As compared to similar runs using rosin and alum, there was a marked reduction in foaming tendency during the period the dimer emulsion was used on the machine, but no other differences in machine operation were noted.

The ultimate sizing was developed on the machine,no appreciable increase in sizing being noted in subsequent curing. The sizing of paper prepared with the ketene dimer emulsion was compared with runs made on the same machine using rosin and alum size. Sizing was determined by noting the time for penetration of the sized sheet by a 20% aqueous solution of lactic acid. The paper sized with 5 lb. of hexadecyl ketene dimer per ton of pulp had a sizing of 893 seconds, while the paper containing 7 lb. of hexadecyl ketene dimer per ton of pulp had a sizing of over 2700 seconds. In comparison six runs of the standard rosin-sized paper containing 1% rosin size prepared on this machine had the following sizing: 333 seconds, 314 seconds, 178 seconds, 355 seconds, 300 seconds, and 393 seconds.

In the above examples definite curing cycles were used to most clearly point up the differences due to the controlled variables in the examples, such as type of ketene, type of pulp, and the pH of the pulp slurry. In commercial practice this is not necessary as can be seen from Examples 29 and 30. When the paper is dried on a heated roll, or by similar means, the heat of drying will generally be suficient to cure the sheet. When an alternative method of drying, such as air drying, is used, simple storage of the paper at room temperature for a day or two will be sufiicient to cure the sheet. However, a separate curing step may be used if desired. When a separate curing step is used, the paper will generally be heated at about 100 C. for five or ten minutes or longer.

In the process of beater sizing as the term is used in the art and in the instant application, it is understood that the ketene dimer may be added to the paper system at that point which is most convenient to the actual manufacturing needs, such as, for example, by addition of the dimer emulsion to the paper furnish at any point prior to sheet formation, sucl as addition at the head box, fan pump, beater engine, Jordan, or the like. Addition at any point prior to sheet formation is included in the term beater addition as used in the art. Furthermore, the ketene dimer emulsions used in the process of the instant invention may be used in conjunction with conventional papermaking ingredients, such as, for example, wet strength resins, fillers, dyes, pigments, and the like, to provide in all cases a paper product having the desired sizing properties.

As stated before, any of the emulsions of U. S. 2,627,- 477 to William Downey may be used. However, particularly preferred are those emulsions which are prepared using a nonionic emulsifier. In addition to those nonionic emulsifiers specifically used by Downey, those nonionic emulsifiers which have been found to be particularly useful include polyoxyethylcne sorbitan trioleate, sold by the Atlas Powder Company under the trade name Tween polyoxyethylene sorbitol hexaoleate, sold by the Atlas Powder Company under the trade name Atlox 1086; polyoxyethylene sorbitol laurate, sold by the Atlas Powder Company under the trade name Atlox 1045; polyoxyethylene sorbitol oleate-laurate, sold by the Atlas Powder Company under the trade name Atlox 1045A;

polyethylene glycol esterfof ro'siffifsold by the Hercules *Powder :Company undef' the 't-rade name Synth'etics V All-1 50 th -pe1 erg 1 ne glyeo1 'esfer-ofaosin, sold by the"Hercules Powder Company -'under'-'the nane-"name fSynfhetics AR'ZOO; the polyethylene glycol ether of an alkylatedphenol, sold by the Hercules Po'wder'Company under the trade name synthetics AF 100; and finally, the ethylene oxide adduct ofa mixture of rosin'and alkylate'cl phenoL-sold by :the Hercules Powder Company under the trade name synthetics B97? Of the anionic emulsifiers, those whichiare particularly preferred are the alkar'ylsulfonates suchas that soldby Nino' Laboratories, lnciu'nder the *trade name *Toximul- 10G, and the sodium salts of=higher-fatty alcohols, such-as those 's'old by'E; *I. 'du'Pont de Nemours and Company, Inc.

under the tradefnarne Aquarex D V 'Irclairnr :1. A process for the internal sizing of paper with a sizing material 'which does not require the use of aprecipitating :agent which'comprises adding to an aqueous suspension of cellulosic paper stock at a point-"ahead of sheet formation =an aqueous emulsion of a keteu'e fdimer, said ketene "dimer having --the--' forn'1ula [RCH=C=G]2 where R is a hydrocarbon radical selected from the group' consisting of-alkyl groups having ;atleast-8 carbon atoms, cycloalkyl having at least 6 carbon atoms, aryl,

' aralkyhiandalkaryl groups, said aqueous suspension being ata 'pH of 5 m9, inclusive, said ketene dimer being added'to the said aqueous suspension to give a conce'n 7. "The process'according' to claim 4 whereinthejalkyl radical isa mixture of hexadecyl and tetradecyl.

8. The process according to claim 4 wherein theketene' dimer is prepared frommontanic acid.

ReferencesvCited in the file or this patent UNITED STATES PATENTS 1,996,707 Nathansohm Apr.2, 1935 2,285,490 Broderick June 9, 1942' 2,595,935 Daniel et al. V May 6, 1952 2,601,597 Daniel et al. June 24, 1952 TDOWHCY" Feb. 3,

O H R- REFERENCES Dohne et 9.1.; Pape r Tra'de J. Nov. 27', 1-941, 138-144.

Claims

1. A PROCESS FOR THE INTERNAL SIZING OF PAPER WITH A SIZING MATERIALK WHICH DOES NOT REQUIRE THE USE OF A PRECIPITATION AGENT WHICH COMPRISES ADING TO AN AQUEOUS SUSPENSION OF CELLULOSIC PAPER STOCK AT A POINT AHEAD OF SHEET FORMATION AN AQUEOUS EMULSION OF A KETENE DIMER, SAID KETENE DIMER HAVING THE FORMULA (RCH=C=O)2 WHERE R IS A HYDROCARBON RADICAL SELECTED FROM THE GROUP CONSISTING OF ALKYL GROUPS HAVING AT LEAST 8 CARBON ATOMS, CYCLOALKYL HAVING AT LEAST 6 CARBON ATOMS, ARYL, ARALKYL, AND ALKARYL GROUPS, SAID AQUEOUS SUSPENSION BEING AT A PH OF 5 TO 9, INCLUSIVE, SAID KETENE DIMER BEING ADDED TO THE SAID AQUEOUS SUSPENSION TO GIVE A CONCENTRATION OF FROM ABOUT 5 PARTS OF SAID KETENE DIMER TO ABOUT 200 PARTS OF SAID KETENE DIMER PER MILLION PARTS OF WATER, FORMING A SHEET FROM THE SAID STOCK AND DRYING THE SAID SHEET.