US2451558A

US2451558A - Chemically treated wood pulp and a method of producing a cellulosic product

Info

Publication number: US2451558A
Application number: US562262A
Authority: US
Inventors: Schlosser Paul Henry; Gray Kenneth Russell
Original assignee: Rayonier Inc
Current assignee: Rayonier Inc
Priority date: 1944-11-06
Filing date: 1944-11-06
Publication date: 1948-10-19
Anticipated expiration: 1965-10-19

Description

Patent ed Oct. 19, 1948 r CHEMICALLY TREATED WOOD PULP AND A METHOD OF PRODUCING A CELLULOSIC PRODUCT Paul Henry Schlosser and Kenneth Russell Gray, Shelton, Wash, assignors to Rayonier Incorporated, Shelton, Wash., a corporation of Delaware No Drawing. Application November fi, 1944, Serial No. 562,262

14 Claims. (Cl. 106-163) This invention relates to the production of cellulosic products and has for its general object the provision of certain improvements in carrying out one or more of the processing steps used in the production of such products. The invention aims particularly to improve the emulsification or dispersion of opacifying agents in the spinning solution, and to suppress the formation of incrustations, sometimes referred to as craters, formed in spinneret orifices. The invention further contemplates, as a new article of manufacture, a chemically prepared wood pulp product having incorporated therein .a mixed ether containing a polyalkylene oxide radical and a substituted aryl hydrocarbon radicaL' In one of its important aspects, the invention involves the use of chemically prepared wood pulp as a source of cellulose in the preparation of cellulosic solutions for the viscose and other processes in which extruded regenerated cellulose is produced, and has for a particular object the use of the said mixed ethers to improve either or both the emulsification and spinning.

The invention is especially applicable to the spinning of viscose rayon in which chemically prepared wood pulp (hereinafter called wood pulp) is used as a source of cellulose and the invention will be described with reference to that process, it being understood that it is also applicable to other processes where aqueous cellulosic solutions are opacified or extruded into filaments or films.

Wood pulp as usually prepared as a source of cellulose for the viscose and related spinning in dustries is of various degrees of purity, and is generally supplied for use in the form of sheets. Normal dissolving wood pulp in present use consists mainly of cellulose and contains anappreciable amount of non-cellulosic impurities, such as hemi-celluloses, fats, resins, waxes, etc. One of the main objects in the manufacture of highly refined dissolving pulp is to remove as much as possible of the non-cellulosic impurities so that a whiter, purer pulp results which is capable in the manufacturing of rayon of producing a higher grade yarn. y

We find, however, that not all of the non-cellulosic impurities which can be removed are undesirable, and in fact certain of such impurities, normally present in small amounts, are highly beneficial as regards the step of emulsifying or dispersing oils or pigments in the viscose. These beneficial impurities which aid the step of emulsiilcation are probably for the most part surfaceactive materials of the anion active class or materials which can give rise to the production of such surface-active materials during the processing of pulp into viscose. In a pulp which has not been highly refined most of these beneficial impurities constitute a portion of the materials removed by organic solvents, as for example ether, benzene, alcohol, et cetera. These beneficial impurities, often loosely termed resins," are mainly of the nature of waxes, fats, and resins, the latter often being present in a relatively small amount.

Furthermore, we find that there are impurities present in pulp which has not been highly refined which have marked effects, both favorable and adverse, on the formation of incrustations in the orifices of the spinnerets during spinning. In theory, the problem of making a good pulp could be solved by removing all the undesirable impurities including degraded cellulose and non-cellulosic carbohydrates while retaining those impurities which facilitate the steps of emulsification and spinning. In practice such a clean-cut separation is difiicult to accomplish directly. We have discovered that better results are obtainable by removing most or all of the impurities, including those which serve beneficially as regards the emulsification step and those which affect spinning, either positively or negatively, and then causing to be present in the viscose, materials of a class entirely different from the natural impurities originally present, and which greatly aid steps of emulsification and spinning.

White, highly purified or refined wood pulps are very advantageous for the production of high grade rayon yarns of superior strength and color, and for this reason, are highly esteemed by the trade. Such highly refined pulps are in general characterized by having an ether extract lower than 0.15% where such values refer to the amount of natural ether extractable material left in the pulp after the purification processes. While our invention is particularly applicable to such high- 1y refined pulp containing not more than 0.15% of ether extractable material, it may be applied with certain advantages to the processing of normal dissolving pulps containing more than 0.15% of ether extractable material, although such pulps do not generally yield the highest grade yarns and their emulsification with oils is not usually accompanied by an great difficulty.

In accordance with the invention a small quantity of a mixed ether containing a polyalkylene oxide radical, and a substituted aryl hydrocarbon radical (as hereinafter more particularly described), is incorporated in the materials used in producing the cellulosic solution prior to releast one cycloalkyl radical.

The mixed ethers of the invention are at least dispersible in water and preferably substantially soluble in water. For reasons of dispersibility the polyaikylene oxide radicals in the mixed ethers of the invention are derived from the first two members of the 1-2 alkylene oxides. These members are ethylene oxide and propylene oxide, or in other words, the 1-2 alkylene oxides having up to 3 carbon atoms.

' Structurally the mixed ethers of the invention have the formula:

where R is an aryl radical substituted by at least one aliphatic alkyl or acyl radical having more than two carbon atoms or by at least one cycloalkyl radical where R1 is hydrogen or methyl, and where a: is a whole number greater than 1.

In view of its higher solubilizing effect a polyethylene oxide chain is the preferred form for the polyalkylene oxide radical. Preferably the polyethylene oxide chain will have from 5-25 ethenoxy residues. Practically it is believed there is no upper limit for the number of ethenoxy groups in the polyethylene oxide radical. Materials with a polyethylene oxide group containing even about 160 ethenoxy groups may be satisfactorily used.

While the mixed ethers used in our invention are preferably substantially water soluble, it is possible to obtain the advantages of the invention in part using compounds of only slight solubility. Thus, mixed ethers containing even the simplest possible polyethylene oxide radical composed of two ethenoxy groups, may be used. Even though such products do not have a great solubility they still possess a suflicient tendency to emulsify so that they may be dispersed in a finely divided state in the viscose yielding in part the advantages of the invention. If, however, a high degree of solubility in water is desired with such agents, as for example, in the preparation of concentrated stock solutions for application to the pulp or in the viscose process, it may be advantageous to combine them with dispersing agents. Such additional dispersing agents should preferably be of a non-ionic nature, for example, a. mixed ether of polyethylene oxide containing a, higher proportion of ethenoxy groups. In the preferable form of our invention, however, suflicient ethenoxy groups will be present in the polyethylene oxide radical so that the products will be substantially water soluble or dispersible without the aid of any additional dispersing agents.

The preferred compounds for use in the invention are mixed ethers containing a polyethylene oxide radical and an alkaryl radical in which the aryl group is substituted by at least one alkyl radical with more than two carbon atoms.

Further from the standpoint of improving emulsiflcation, the most preferred class of materials are mixed ethers containing a polyethylene oxide radical and an alkyl phenyl hydrocarbon radical having at least one substituted alkyl radical with 3-30 and especially from 7-20 carbon atoms. In the very best cases of all the phenyl radical will be substituted by only a single alkyl radical of 7-20 carbon atoms. For best results the polyethylene oxide radical will have from 5-25 ethenoxy residues. Such compounds are also particularly effective in suppressing incrustations in spinneret orifices during spinning.

The mixed ethers of the invention may be prepared from substituted phenols by any of the known methods for reacting ethylene oxide or propylene oxide with a phenol. They may also be prepared by etherifying substituted ph nols with polyalkenoxy glycols, as, for example, by reacting the sodium salt of a substituted phenol with a halogen hydrin of the polyethylene glycol. The substituted phenols may also be reacted with mixtures of ethylene oxide and propylene oxide or with one of these materials following use of the other.

We prefer, however, to react ethylene oxide at moderate temperatures with a substituted phenol (in the most preferred cases with an alkylation product of phenol itself), incorporating an alkali as catalyst with the phenol. In practice the products will usually be mixtures having some variation in the length of the polyethylene oxide chains but the products are quite satisfactory to use for the purpose of the invention in the form of such mixtures.

Again when the alkaline catalyst used consists of a small amount of aqueous caustic soda (e. g., 48% NaOH) all of the ethylene oxide will probably not be consumed in extending the length of the polyether chain on the substituted phenol but a portion (in view of the small amount of water present) will be consumed with the formation of polyethylene oxide. The presence of polyethylene oxide is, however, not harmful to our invention.

Instead of reacting ethylene oxide with the substituted phenols, their glycol ethers may be used since these would be initial products in the formation of the polyether chains.

. In condensing ethylene oxide with a substituted phenol it is quite satisfactory to base the desired molar ratio on the assumption that the entire weight of ethylene oxide will react to form polyether chains on the phenol, homogeneous as to length. This may be done since small variations in the ratio of ethenoxy do not produce very great difierences in the properties. Furthermore, it is not necessary to use exact stoichiometrical proportions of ethylene oxide. Thus, for example, if pure p-diisobutyl phenol were treated with 12.5 moles of ethylene oxide, mixtures of mixed ethers would be obtained in which chains of 12 and 13 ethenoxy groups would predominate.

Again it is not necessary to use pure substituted phenols. Thus even while a single substitutin alkyl of more than two carbon atoms is most preferred, actually such an intermediate for mixed ether preparation may practically contain as well as the predominating mono-alkyl phenol, small amounts of dior poly-substituted as well as unsubstituted phenol.

After completionof the reaction with ethylene oxide the reaction products may be used directly if they are to be added to the viscose. Where, however, alkali has been used as catalyst and the products are to be added to the pulp the residual alkali should be neutralized in any convenient manner-as for example, by 30% H2804 or concentrated HCl. For the purposes of our invention frequently no further purification will be lie-- quired. Where an extremely light-colored proddrying and decolorizing the benzene solution by addition of sodium sulphate and decolorizing charcoal. After filtering, the product was isolated by evaporating of! the benzene, finally applying vacuum.

The alkyl, acyl or cycloalkyl substituted phenols used for preparing the mixed ethers can be readily prepared by the methods known to the art. By phenols is meant not just phenol itself but all monohydroxy substitution products of aromatic hydrocarbons. The alkyl or acyl groups may be branched or straight chain in character. Fbr practical reasons-the alkyl phenols having from 3-30 carbon atoms in thealkyl group and especially from 7-20 carbon atoms are preferred. Also the introduction of branched rather than straight chain alkyls into the phenols will in most cases be more practical. This is not only because in many cases the alkyl or alkylene compounds reacted with the phenol will be of a secondary or tertiary character or at least of a branched chain structure. Actually even in many cases where normal primary alkyi compounds are reacted with phenols the result will still be the introduction of a branched chain rather than a straight chain alkyl.

Substituted phenols may be used for the preparation of mixed ethers irrespective of the position of the substituted alkvl, cycloalkyl' or acyl group. Thus in the case of a monocyciic phenol the substituted group or groups may be m-, or pto the hydroxyl or as a mixture of these. Again with polycyclic phenols substituted products may be used irrespective of the position of the substituting group. All the substituted phenols used, however, are monohydroxylic, i. e. they are substituted aryl hydroxides.

Phenols particularly useful for preparing substituted phenols for use as intermediates in the production of the mixed ethers of the invention are those of the-benmne and naphthalene series. These are especially phenol, o, m, and p cresol, a and s naphthol and mixtures of these.

Methods of preparing the substituted phenols from the phenols (by which term is included phenol, cresols, xylenols, naphthols, etc.) include the reaction with the phenols of alcohols, alkyl halides or alkyl esters in the presence of a suitable condensing agent. Another practical well-known method involves the addition of an olefine to the phenol usually in the presence of a catalyst. With phenol itself this usually results in introduction of the alkyl in the para position to the hydroxyl. Examples of olefines which may be used are diisobutylene isododecylene, etc.

It is not necessary to introduce pure alkyls into the phenols. Thus mixtures of oleflnes or of alkyl compounds may be reacted with the phenols. As an example of a suitable mixture of alkyl compounds may be mentioned the use of chlorinated rinated hydrocarbons and generally averaging from 12-20 carbon atoms.

solving the neutralized product in benzene, and

The production of acyl substituted phenols may be accomplished by the well-known Friedel-Crafts reactions.

As examples of mixed ethers which may be used in the invention are mixed ethers of polyethylene oxide and the following phenols:

Alkyl phenols p-n-Bu'tyl phenol, 'p-tertiary butyl phenol, D-mmYn-tetramethyl butyl phenol, decyl phenol, dodecyl phenol, cetyl phenol, octadecyl phenol, (2- ethyl heXyl) phenol, oleyl phenol, such polyalkyl phenols as di and trioctyl phenols, amyl cresol, dodecyl cresol; substituted naphthols such as iso propyl naphthol, iso butyl naphthol, dodecyl naphthoi.

Cycloalkyl phenols p-Cyclohexyl phenol, cycl-ohexyl-cyclohexyl phenol, bomyl phenol.

Acyl phenols Butyryl, valeryl, dodecyl, stearoyl phenols and the corresponding cresols, naphthols and xylenols. As previously stated the most preferred mixed ethers are those containing predominantly a mono alkyl phenyl radical. An example of such mixed ethers which are particularly effective in kerosene fractions predominating in monochloimproving emulsification and improving spinning are those represented by the following formula:

CH: CH:

cm-d-cm-dOo 023.0 ,11

nection with any of the steps in producing re'generated cellulose, they are especially beneficial when present in a spinning solution containing an opacifying or delustering agent, and when in contact with the spinneret due to their presence either in the spinning solution or in the spin bath.

In the usual viscose process the sheets are first subjected to a steeping step to convert the cellulose to alkali cellulose, and the pressed sheets of alkali cellulose are then shredded to form a fiufiy mass of fibers. The fluffy mass is xanthated, dissolved in dilute caustic soda and the solution commonly known as viscose filtered to remove undissolved fibers and gel-like materials, and ripened to impart the desired properties for satisfactory spinning.

When viscose rayon is delustered by incorporating a suitable opacifying agent in the spinning solution, usually an oil or a pigment such as titanium dioxide, it is necessary in order to get a uniform emulsification or dispersion of the agent throughout the body of the viscose solution to use an emulsifying or dispersing agent. The mixed ethers of the invention produce an exceptionally good emulsifying and dispersing efiect which is quite remarkable in view of the small quantities used. The emulsification is characterized by the fineness, not only of the average particle size, but also by the uniformity of size so that the resulting viscose solution is substantially free of even small amounts of large globules which weaken the filaments on spinning.

Viscose solutions used in making rayon are preferred range of 5-20 corporated either usually spun through metal spinnerets having that they are in such contact with the metallic spinneret during spinning that the formation-of the craters is greatly minimized. The mixed ethers exert such a powerful influence on the materials present that only very small quantities are necessary to accomplish the results sought. The extremely effective suppression of the craters is illustrated in some operations by a reduction of from 80 to 95 per cent in the crater formation.

The mixed ethers may be incorporated in the wood pulp or at any stage of the viscose process. For treating the pulp, the compounds may be inin the bulk pulp before sheet formation or in the sheets in any suitable stage as by spraying the pulp with an aqueous solution or dispersion of the compound, or by immersing in a solution or dispersion. A most practical and convenient method of I securing the presence of the desired amount of mixed other is to incorporate the mixed ether in the refined wood pulp while it is on the sheet forming machine, as by means of sprays or a rotating roll. In any case, there is produced a refined pulp product having the compound incorporated therein. When the compound is incorporated in the pulp, as by the manufacturer thereof, the pulp comes to the rayon manufacturer in a form calculated to secure the full advantages of the invention in the preparation and processing of the refined pulp into rayon by the viscose process.

The mixed ethers, whether added to the spinning solution or to the pulp, come into direct contact with the orifices of the spinneret and suppress the formation of incrustatlons on the walls of the orifices.

In order to efiect the contemplated improvements, the amount of the compound used is relatively small, ranging from 0.01-0.20% on the bone dry weight of the pulp used. In most cases the preferred amounts for improving spinning will generally be about 0.08-0.10.

As heretofore described, the mixed ethers and especially those containing an alkyl phenyl group also bring about important improvements in emulsification in that they give emulsions characterized not only by extraordinary fineness of particle size, but also by exceptional uniformity of particle size and by exceptional stability in regard to maintaining the particle size. The amount of the mixed ethers required for securing the maximum improvement in emulsification is generally somewhat less than the amount required for securing the contemplated improvement in suppressing or minimizing incrustation formation during spinning. Thus the maximum improvement in emulsification will generally be brought about by from 0.025%-0.05% of the mixed ether and the amount used for this purpose will commonly be about 0.03%. In order to secure the additional benefit of substantially suppressing or minimizing incrustation formation during spinning, the mixed ether should be present in amount of 0.08-0.10% or higher. By using such amounts of mixed ether of the order of 0.08 0.10% the emulsions are substantially as fine and uniform as when using the' optimum of 0.025-

. 8 9.05%. Emulsions prepared, however, in the presence of the higher amount of mixed ether may under certain circumstances have a slight tendency to partially separate as a cream or scum during the various viscose processing steps or during the aging period. Accordingly, when both emulsification and suppression of incrustations during spinning are of paramount concern, we prefer to add only 0.025-0.05% of a mixed ether (especially a mixed ether containing an alkyl phenyl group) but to still obtain the contemplated improvement in cratering or an even greater improvement by adding an additional small amount of a cation-active amino compound. In such cases the amount of the mixed ether will preferably be about 0.03% and the amount of cation-active amino compound will preferably be about 005% though it may be added in amounts up to 0.20%.

As two examples of products both of which are cation-active amino compounds especially suitable for use in combination with the mixed ethers as described above are (1) a mixture of the mono and diamides of diethylene trlamine and coconut fatt acids and (2) a reaction product consisting substantially of mixed diethylene triamine diamides from coconut acids and a lower acid such as acetic acid.

So far as the objectives of the invention are concerned, there is little, if any, improvement by increasing the amount of the mixed ethers above 0.20% and such higher amounts frequently, give rise to certain disadvantages. These disadvantages include the causing of excessive soft. ness in the sheet, resulting in mechanical difliculties in steeping, excessive ball formation in xanthation, and difficulties in the dissolvingoperation due to excessive foamingin the viscose solution. Also, there may be considerable difllculty in obtaining a completely deaerated viscose which is necessary for satisfactory spinning. Higher concentrations of the compound may also unduly lower the surface tension of the viscose, thus changing the coagulating conditions so that the viscose cannot be satisfactorily spun by standard methods, causing the filaments to break and the thread to stick to the godet wheels or thread guides.

While it is our preferred practice to incorporate the compound in the pulp, the presence of the compound during the processing steps of opacifying and spinning may be secured in any other appropriate manner. However, we believe it will generally be found more advantageous to incorporate it in the pulp, both as a matter of convenience and economy in preparing and processing the viscose, and because a very uniform distribution of the compound throughout the viscose is easily attained. The next best manner of obtaining very effective results is to spray the agents into the shredder prior to the completion of shredding. With the mixed ethers containing alkyl phenyl radicals the method of adding the agents is of particular importance in regard to imparting 'anti-creaming properties if the viscose is to be subsequently opacified. Whether this is a question of the agents themselves undergoing some change during the xanthation or whether it is merely a question of the uniformity of the distribution in the viscose, we do not know. In any event, for the most effective results the agents should be added not later than prior to the completion of shredding and preferably to the pulp prior to use in the viscose process.

This application is a continuation-in-part of following formula:

rated therein from 0.01 to 0.2 per cent by weight based on the bone dry weight of the pulp of a mixed ether having the following formula:

where R is an aryl radical substituted by at least one radical selected from the class consisting of an alkyl radical with more than two carbon atoms, an acyl radical with more than two carbon atoms and a cycloalkyl radical; where R1 is selected from the group consisting of hydrogen and methyl and where .1: is a.whole number greater than 1.

2. As a new article of manufacture, a chemically prepared wood pulp product containing not more than 0.15 per cent ether extractable material and having incorporated therein from 0.01 to 0.2 per cent by weight based on the bone dry weight of the pulp of a mixed ether having the where R is an aryl radical substituted by at least one radical selected from the class consisting of an alkyl radical with more than two carbon atoms, an acyl radical with more than two carbon atoms and a cycloalkyl radical; where R1 is selected from the group consisting of hydrogen and methyl and where a: is a whole number greater than 1.

3. The improvement in the production of regenerated cellulose products by the viscose process from chemically prepared wood pulp which comprises incorporating in the viscose a mixed ether having the following formula:

R- 0H0H10 H where R is an aryl radical substituted by at least one radical selected from the class consisting of an alkyl radical with more than two carbon atoms, an acyl radical with more than two carbon atoms and a cycloalkyl radical; where R1 is selected from the group consisting of hydrogen and methyl and where m is a whole number greater than 1.

4. The improvement in the production of regenerated cellulose product-s by the viscose process from chemically prepared wood pulp containing not more than 0.15% ether extractable matter which is subjected to shredding 'which ding the alkali cellulose a mixed ether having the following formula:

where R is an aryl radical substituted by at least one radical selected from the class consisting of an alkyl radical with more than two carbon atoms, an acyl radical with more than two carbon atoms and a cycloalkvl radical; where R1 is selected from the group consisting of hydrogen and methyl and where .1: is a whole number greater than 1.

5. The improvement in the production of a regenerated cellulosic product from chemically prepared wood pulp by the viscose process which comprises adding to the pulp prior to use in the 10 viscose process a mixed ether having the following formula:

RO(CHCH:O) n

where Ris an aryl radical substituted by at least one radical selected from the class consisting of an alkyl radical with more than two carbon atoms, an acyl radical with more than two carbon atoms and a cycloalkyl radical; where R1 is selected from the group consisting of hydrogen and methyl 'comprises adding prior to completion of shredand where a: is a whole number greater than 1.

6. As a new article of manufacture, a chemically prepared wood pulp product having incorporated therein from 0.01 to 0.2 per cent by weight based on the bone dry weight of the pulp of a mixed ether containing a polyethylene oxide radical with from 5-25 ethenoxy residues and an alkyl phenyl radical in which the phenyl radical is substituted by an alkyl radical with from 7-20 carbon atoms.

7. As a new article of manufacture, a chemically prepared wood pulp product containing not more than 0.15 per cent ether extractable material and having incorporated therein from 0.01 to 0.2 per cent by weight based on the bone dry weight of the pulp of a mixed ether containing a polyetheylene oxide radical with from 5-25 ethenoxy residues and an alkyl phenyl radical in which the phenyl radical is substituted by an ether containing a polyethylene oxide radical with from 5-25 ethenoxy residues and an alkyl phenyl radical in which the phenyl radical is substituted by an alkyl radical with from 7-20 carbon atoms.

9. The improvement in the production of a regenerated cellulosic product from chemically prepared wood pulp by the viscose process which comprises adding to the pulp prior to use in the viscose process a mixed ether containing a polyethylene oxide radical with from 5-25 ethenoxy residues and an alkyl phenyl radical in which the phenyl radical is substituted by an alkyl radical with from 7-20 carbon atoms.

10. As a new article of manufacture,a chemically prepared wood pulp product having incorporated therein from 0.01 to 0.2 per cent by weight based on thebone dry weight of the pulp of a mixed ether having the following formula:

on; cHi' Hz 0 Ha on, em cm- E-cm-e-O0 (ozmomr CH5 CH3 where a: is a whole number from 5 to 25.

12. The improvement in the production of regenerated cellulose products by the viscose process from chemically prepared wood pulp which com prises incorporating in the viscose a mixed ether having the following formula:

where a: is a whole number from 5 to 25.

13. The improvement in the production of regenerated cellulose products by the viscose process from chemically prepared wood pulp containing not more than 0.15% ether extractable matter which is subjected to shredding which comprises adding prior to completion of shredding the alkali cellulose a mixed ether having the following formula:

HI C H:

where :c is a whole number from 5 to 25.

14. The improvement in the production of a regenerated cellulosic product from chemically prepared wood pulp by the viscose process which comprises adding to the pulp prior to use in the viscose process a mixed ether having the following formula:

CH; CH9 onr-o-pnr-o-O-owmmmr (5H1 (3H1 where a: is a whole number from 5 to 25. I

PAUL HENRY KENNETH RUSSEl-L GRAY. 1

REFERENCES CITED The following references are of record in the file oi this patent:

UNITED STATES PATENTS