US3392083A - De-inking printed waste cellulosic stock with nonionic detergent and a polyol - Google Patents

Description

y 9, 1968 R. H. ILLINGWORTH 3,

DE-INKING PRINTED WASTE CELLULOSIC STOCK WITH NONIONIC DETERGENT AND A POLYOL Original Filed Aug. 17, 1966 WATE R SOURCE DETERGENT REACTOR WASTE PAPER CH EST DILUTION WASHER 8. THlCKENER (3-STAGE) ACIDIF'ICATION ACID WASTE EFF'LUENT THICKENER WEB FORMING INVENTOR. ROBERT H. ILLINGWORH BY May, I a/40! I PM ATTORNEYS United States Patent 3,392,083 DE-INKING PRINTED WASTE CELLULGSEC STOCK WllTH NONIONIC DETERGENT AND A POLYOL Robert H. Illingworth, Madison, N.J., assignor to Garden State Paper Company, Inc., Garfield, N.J., a corporation of New Jersey Continuation of application Ser. No. 573,127, Aug. 17, 1966. This application July 3, 1967, Ser. No. 651,048 13 Claims. (Cl. 1625) ABSTRACT OF THE DISCLOSURE A method of de-inking waste printed paper by pulping the waste paper with a polyol such as a glycol and a nonionic surface active agent containing a polyoxyalkylene chain of at least two alkenoxy groups and derived from alkyl phenolic compounds in which the total number of alkyl carbon atoms is between 4 and 24.

This application is a continuation of copending application Ser. No. 573,127, filed Aug. 17, 1966, now abandoned, and a continuation-in-part of copending application Ser. No. 193,448, filed May 7, 1962. The aforesaid application Ser. No. 573,127 was a continuation of and copending with application Ser. No. 294,410, filed July 11, 1963, now abandoned. The aforesaid application Ser. No. 193,448 was a continuation-in-part and copending with the following applications, now abandoned: Ser. No. 84,908, filed Jan. 25, 1961, Ser. No. 95,722, filed Mar. 14, 1961, and Ser. No. 95,723, filed Mar. 14, 1961.

This invention relates to improvements in de-inking printed waste cellulosic stock.

It is an object of the present invention to-provide improved methods and agents for de-inking printed cellulosic material to produce a pulp that can be readily and economically handled on conventional paper making machines to produce newsprint, magazine or book stock.

It is another object of this invention to provide irnproved processes and agents for de-inking waste printed paper to produce a pulp at least substantially equal, and

often superior, in brightness, color and strength to that of virgin pulp.

Still another object of this invention is to provide improved agents and methods capable of de-inking a wide variety of waste printed paper, regardless of the type of ink or method of printing originally employed to produce the printed paper.

Other objects of the present invention will in part be clear and will in part appear hereinafter.

Commercial conversion of waste newspaper, magazine and other types of printed waste cellulosic stock to a pulp capable of reuse in forming paper or other cellulosic products has been a much sought after goal in the paper industry.

Although many processes for de-inking such printed cellulosic material have been heretofore proposed, in general, these have not proved commercially satisfactory. Many of these processes for example, when tested on a commercial scale with the general run of waste newspaper and junk, fail to yield a pulp suitable for reuse as newsprint, magazine or book stock. The failure may be attributable to the fact that many of these processes drive a significant portion of the ink particles into the cellulosic fibers, thereby rendering the pulp gray and unsatisfactory for use except for the manufacture of low grade paper materials, for example, low grade packaging cartons. Other of these processes are so expensive, time-consuming, laborious and complicated that they are simply not economically feasible.

3,392,983 Patented July 9, 1968 In the copending applications referred to hereinbelow, there are described processes for de-inking waste newspaper, magazines and other types or printed waste cellulosic stock which utilize, as the active de-inking agent, certain nonionic detergents, e.g., ethylene oxide adducts of alkyl phenols.

Such nonionic detergents, by themselves, give satisfactory de-inking results when used with the general runof-the-mill waste newspaper and magazine stock produced; for example, standard planographic, e.g., offset, printing techniques and inks. With certain waste printed cellulosic stock, however, e.g., paper printed by intaglio such as rotogravure techniques and inks, nonionic detergents of the type specified above and in the copending applications do not, by themselves, accomplish a completely satisfactory de-inkin job.

As will be readily apparent, in commercial tie-inking, it would be highly advantageous if the process would be able to handle a wide variety of waste printed stock, regardless of the type of ink or printing technique originally used in producing the waste printed paper. Otherwise, a costly and time-consuming paper separation step would have to precede de-inking. The economics of paper de-inking are such that a paper separation or classification step could well spell the difference between success and failure.

According to the present invention, it has been discovered that improved de-inking results may be realized by utilizing as the active de-inking agent the combination of (l) a nonionic detergent, and (2) a polyol.

This combination of ingredients, when used as described herein, has been found to be effective in de-inking all types of waste printed cellulosic stock, regardless of the type of ink or printing technique originally utilized in producing the paper.

The polyols suitable for use are those compounds having more than one hydroxyl (-OH) group, each of which is attached to separate carbon atoms of an aliphatic skeleton. This group includes glycols, glycerol, pentaerythritol, and also such compounds as trimethylolethane, trimethylolpropane, 1,2,6-hexanetriol, sorbitol, inositol, and the like. The dihydric polyols, e.g., the glycols, such as ethylene glycol, diethylene glycol, trimethylene glycol, propylene glycol, dipropylene glycol, and the like, are especially suitable. Of the glycols, ethylene glycol is preferred.

The nonionic detergents suitable for use may be described as water-soluble synthetic nonionic surface active agents containing a polyoxyalkylene chain of at least two alkenoxy groups, and derived from alkyl phenolic compounds in which the total number of alkyl carbon atoms is between 4 and 24.

The above defined nonionic surface active agents operative in the instant invention may be more specifically represented by the general formula wherein R represents the residue of a suitable alkyl phenol, R represents hydrogen or lower alkyl, and n has a value from 2 to or more and usually from about 4 to 30. Compounds of this type are well known in the art and are disclosed along with suitable methods for their preparation in US. Patent 2,946,921. In general, they may be obtained by condensing a polyglycol ether containing the required number of alkenoxy groups or an alkylene oxide such as propylene oxide, butylene oxide, or preferably ethylene oxide, with a suitable alkyl phenol. The amount of alkylene oxide condensed with the alkyl phenol, i.e., the length of the polyoxyalkylene chain, will depend pri marily upon the particular compound with which it is condensed. As a convenient rule of thumb, approximately 1 mole of alkylene oxide should be employed for each two carbon atoms in the alkyl phenol. However, the optimum amount of alkylene oxide may readily be determined in any particular case by preliminary test and routine experimentation.

An especially suitable nonionic detergent is an ethylene oxide adduct of dodecylphenol having a formula corresponding to that indicated above, wherein n is between about 8 and 15. Another particularly suitable non-ionic detergent is a condensation product of nonyl-phenol and ethylene oxide having the structural formula wherein n is an integer between 8 and 15.

The amount of nonionic detergent and polyol employed should be carefully controlled. Based on the weight of paper, the amount of each of these materials may vary between about 0.1 and 3.0 percent. Especially good results are obtained when about 1 and 2.5 percent by weight of paper of each material is employed, and this amount is preferred.

The relative proportion of nonionic detergent to polyol may be varied over fairly wide ranges. In general, the weight ratio of nonionic detergent to polyol may vary from about 10:1 to 1:10, but preferably it is about 2:1 to 1:2.

Preferably, the nonionic detergent and polyol are admixed, and the admixture added to water to form the deinking solution.

The combined de-inking agent constitutes a part of the present invention, and, as indicated above, comprises compositions satisfying the following formula:

Parts by weight Nonionic detergent 10 to 1 Polyol 1 to 10 The temperature of the de-inking solution may vary anywhere from room temperature, e.g., 40 to 70 F., up to the cloud point or volatilization temperature of the nonionic detergent, although preferably the de-inking solution is employed at room temperature.

Best results are achieved with the de-inking solutions described herein when they are alkaline in pH and it therefore is desirable that an alkali be included therein. Although any suitable alkali or alkaline earth metal hydroxide or salt may be employed, the alkali metal hydroxides and salts, such as sodium hydroxide, potassium hydroxide, soda ash and the like are preferred. Enough of the alkali should be added to maintain the pH of the de-inking solution between about 7.0 and 10, or even higher, and preferably at least about 7.1.

In preparing the de-inking solution, water is charged to the reactor or pulper and the active de-inking agents described hereinabove added. The de-inking agents are preferably added to the water prior to the addition of the Wastepaper or junk.

To the resulting solution is added the printed paper, scrap or junk. The printed cellulosic charge may, if desired, be shredded by appropriate means prior to treatment. This, however, is not necessary, and the waste material may be added to the treating solution without shredding or without any subdivision in size whatsoever. It is one of the advantages of this invention that costly shredding or pulping techniques prior to de-inking need not be employed. Thus, the waste material to be de-inked is preferably added to the treating solution in its naturally dry condition, i.e., without being subjected to moisture or water other than that which is normally present in the atmosphere. Although de-inking will occur if the Waste material is first slurried or pulped in water, in general it has been found that the results achieved are inferior to those obtained when the waste material is added to the treating solution in its naturally dry condition, i.e., in equilibrium with its natural atmospheric environment. Although not wanting to be restricted to this interpretation, it appears that wetting the waste material with water prior to subjecting it to the chemical treatment described herein has a tendency to set the ink and make it more difficult to remove from the cellulosic fibers. The amount of the scrap or junk added to the treating solution should be controlled. In general, the percent of cellulosic material by Weight of the aqueous treating solution should be below 10 percent and preferably below 6.0 percent, or between about 4.0 and 6.0 percent. Good results are obtained when the de-inking solution contains about 5 to 5.5 percent by Weight of paper and this value appears to be optimum. The scrap is retained in the treating solution until substantial defiberization takes place. Depending upon the degree of agitation in the reactor, the time in the reactor may vary between about 10 and 50 minutes, and is usually between about 20 and 40 minutes.

Following treatment, the defibered material is dropped to a chest or other suitable reservoir, after which it is diluted with water to a solid content of between about 0.5 and 1.5 percent, preferably about 1.0 percent, based upon the solution weight.

Following dilution, the pulp is separated from the solution and washed and thickened by well known methods. The resulting pulp is then acidified to a pH of between about 4 and 6.5, preferably between about 4.5 and 5.5, thickened and then formed into a web.

This acidification step has been found to significantly increase the brightness of the paper produced from the recovered pulp, and also voids the necessity of bleaching the pulp. Moreover, it has been discovered that acidification tends to set any residual ink particles which may be present, thereby preventing such particles from coming off on the felts and rolls during the web forming step. Such residual ink particles in the past have been found to create considerable difficulty and aggravation during web forming.

The recovered stock may be blended with fresh virgin sulfate or sulfite stock, or with additional recovered stock to rlnake cellulosic articles, such as newspaper, and so fort A suitable arrangement for carrying out the de-inking process is illustrated in the accompanying drawing, which is a flow sheet of the steps in a particularly suitable process.

As indicated in the drawing, water from an appropriate source is charged to a suitable reactor or pulper. The reactor or pulper used in the process is equipped with a stirrer or agitator of any appropriate shape which will agitate and defiber the cellulosic material. If desired, baifie plates may be attached to the interior of the reactor to assist the agitation action.

After the water has been charged to the reactor, the combined de-inking agents described herein are added and agitation continued until the agents are dispersed and/or dissolved.

Wastepaper, junk, or other printed cellulosic material is then added to the reactor.

After a suitable period of time in the reactor, the mixture is dropped to a storage chest which is preferably equipped with a suitable agitator. If desired, water may be charged to the chest to reduce the solid content of the mixture therein. The mixture from the chest is then diluted to the solid content indicated hereinabove, and washed and thickened in a well known manner as, for example, by a Lancaster three-stage washer and thickener equipped with a 45 mesh wire screen. The pulp may be thickened to about a 5 percent solid consistency, or between about a 3 to 8 percent solid consistency in this manner. Cocurrent or countercurrent washing, alone or in combination, may be used. The resulting pulp is then acidified to the pH indicated hereinabove by addition thereto of a dilute solution of a suitable acid, as for example, alum, sulfuric acid, S0 and so forth. The resulting pulp may be finally thickened and formed into a web. The number of thickening and washing steps preceding the acidification step, it should be understood, is not critical, and the number of. such. treatments will be governed largely by the type of equipment employed. Also, if desired, the pulp may be bleached, using a suitable bleaching agent, following acidification. Ordinarily, however, bleaching is not required. When only acidification is used, the pulp need not be, and preferably is not, washed following acidification.

The nature of the invention will be made more clear from the following examples, which are exemplary of the mode of carrying out the de-inking process already described. I

Example 1 City water is charged to a reactor, which is an eight foot diameter hydrapulper, arranged for batch operation, and equipped with a inch diameter rotor for operation at 247 rpm. by a HF. motor and one inch diameter extraction blades. Based on the weight of newspaper, 1.6 percent of an ethylene oxide adduct of dodecyl phenol and an equal amount of ethylene glycol are charged to the reactor and the admixture agitated.

To the resulting solution is added about 5 percent by weight, based upon the weight of the solution, of nonshredded, dry newspaper scrap and junk.

Sodium hydroxide is added to raise the pH of the aqueous slurry to about pH 7.5.

Agitation is contained with stirring for about 25 min utes. The pulp is then dropped to a chest, after which it is diluted with water to give a mixture'comprising about 1 percent by weight of pulp. The pulp is then thickened and washed by a Lancaster three-stage washer and thickener equipped with a mesh Wire screen. The solid content of.

pulp drawn off the Lancaster machine is about 5.0 percent by weight. The pulp is then acidified to a pH of 5.0 by addition of S0 gas. Following acidification, the pulp is again thickened and formed into a web.

The pulp has a substantially white appearance and can readily be handled on conventional paper making machines to produce a paper web sheet.

Paper sheets prepared from the pulp following acidification have an average T.A.P.P.I. standard brightness of 58 to 62.

Example 2 Example 1 is repeated with the exception that an ethylene oxide adduct of nonyl phenol is substituted for the ethylene oxide dodecyl phenol. Similar results are obtained.

Example 3 Example 1 is repeated with the exception that diethylene glycol is substituted for ethylene glycol. Similar results are obtained.

Example 4 Example 1 is repeated with the exception that propylene glycol is substituted for ethylene glycol. Similar results are obtained.

Although in the examples the de-inking agents are added to the water directly, it should be understood that the agents may also be introduced into the water in association wtih the waste cellulosic material, as for example, by spraying the waste material with the de-inking agents prior to introduction of the waste newspaper into the pulper or reactor.

Although in the examples the de-inking agents are semibatch process is indicated, it should be understood that the de-inking may be carried out using a continuous process, as will be obvious to those skilled in the art.

The invention in its broader aspects is not limited to the specific compositions, steps and methods described, but departures may be made therefrom within the scope of the accompanying claims without departing from the principles of the invention and without sacrificing its chief advantages.

What is claimed is:

1. In a method of de-inking waste printed paper, the

6 improvement which comprises pulping waste printed paper in an aqueous solution with a small effective deinking amount of a nonionic surface active agent and a polyol, the nonionic surface active agent corresponding to the formula wherein R represents the residue of an alkyl phenol in which the total number of carbon atoms is between 7 and 24, R represents hydrogen or lower alkyl, and n is an integer of from 2 to 100, and the polyol being a compound having more than one hydroxyl (-OH) group, each of which is attached to separate carbon atoms of an aliphatic skeleton, the weight ratio of nonionic surface active agent to polyol being between 10:1 and 1:10.

2. The method of claim 1 wherein the polyol is a member selected from the group consisting of glycols, glycerol, pentaerythritol, trimethylolethane, trimethylolpropane, 1, 2,6-hexanetriol, sorbitol, inositol and mixtures of the foregoing.

3. A composition of matter capable, when mixed in appropriate amounts with water and waste printed paper, of de-inking the waste printed paper, said composition of matter consisting essentially of:

(a) a nonionic surface active agent corresponding to the formula wherein R represents the residue of an alkyl phenol in which the total number of carbon atoms is between 7 and 24, R represents hydrogen or lower alkyl, and n is an integer of from 2 to 100, and

(b) a polyol containing more than one hydroxyl group (-OH), each of which is attached to separate carbon atoms of an aliphatic skeleton, the weight ratio of nonionic surface active agent to polyol being between 1021 and 1:10.

4. A composition of matter as in claim 3 wherein the weight ratio of nonionic surface active agent to polyol is between 2:1 and 1:2.

5. A composition of matter as in claim 3 wherein the polyol is selected from the group consisting of glycols, glycerol, pentaerythritol, trimethylolethane, trimethylolpropane, 1,2,6-hexanetriol, sorbitol, inositol and mixtures of the foregoing.

6. A composition of matter as in claim 5 wherein the weight ratio of surface active agent to polyol is between 2:1 and 1:2.

7. The method of claim 1 wherein the nonionic surface active agent corresponds to the formula R (CH CH -O--) -H wherein R is the residue of alkyl phenol in which the total number of carbon atoms is between 7 and 24.

8. A process for de-inking waste printed paper which comprises pulping printed cellulosic material in an aqueous solution comprising a nonionic surface active agent and a polyol, the nonionic surface active agent corresponding to the formula wherein R represents the residue of an alkyl phenol in which the total number of carbon atoms is between 7 and 24, R represents hydrogen or lower alkyl, and n is an integer of from 2 to 100, and the polyol being a member selected from the group consisting of glycols, glycerol, pentaerythritol. trimethylolethane, trimethylolpropane, 1, 2,6-hexanetriol, sorbitol, inositol and mixtures of the foregoing, the weight ratio of nonionic surface active agent to polyol being between 10:1 and 1:10, the amount of printed cellulosic material being below about 10% by weight of the aqueous solution, and the amount of nonionic detergent and polyol being an effective de-inking amount, the amount of each being between about 0.1 and 3 percent, based upon the weight of the cellulosic material, continuing the pulping for a sufiicient time to de-ink, and separating the resulting de-inked pulp from the aqueous solution.

9. The method of claim 8 wherein the aqueous solution has an alkaline pH.

10. The method of claim 9 wherein the pH of the pulp is reduced to between about 4.0 and 6.50 following wash- 11. The method of claim 10 wherein the amount of printed paper charged to the pulper is between about 4.0 and 6.0 percent by weight of the solution.

12. The method of claim 11 wherein the amount of nonionic detergent and polyol is each between about 1 and 2.5

. v r q "s 7 percent, based upon the weight of the cellulosic material. 13. The method of claim 8 wherein the weight ratio of nonionic surface active agent to polyol is between 2:1 and 1:2.

References Cited UNITED STATES PATENTS 8/1962 Grossmann etal. 162 -5 3,051,610 3,072,521 1/ 1963 Samuelson et al. -1625 10 3,158,530 11/1964 Anastasio 162-5 S. LEON BASHORE, Primary Examiner.

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