US2686132A - Improved refined wood pulp and a method of improving it - Google Patents

Description

Patented Aug. 10, 1954 IMPRGVED REFINE METHODOF I Kenneth Russell Gray, Shelton,

to" Rayoni'er Incorpo corporation ofDelaware WOOD PULP AND A MPROVING IT Wash-a assignor rated, Shelton, Wash, a

No'Drawing. Application July 14, 1950,

Seria-FNO. 173,949

M'GIaimS; (Cl; 106-163.)

This invention: relatestar chemically prepared wood pulp such'as the so-called dissolving pulp, hereinafterpfor convenience; calledreline'd woo'd pulp The invention has. for: anlobiecti the-provision' of an: improved refin'ed: wood pulp and a method of producing the same The: improved wood pulp offthe inven'tion is: especially suitable for the manufacture" of regenerated cellulose products by the. viscose processan'dZ for: the: pro duction of. cellulose. derivatives: such as. cellulose acetate, etc.

The invention further relates to the; production of cellulosic' products: from refined wood pulp and aims to provide certain improvements in carrying out one orm'ore of the processingsteps used inthe production or. such products;

In one of its important aspects the invention relates to producing a pulp" of uniform characteristics from different pulps having different percentages of unsaponifiable and saponifiable ether extractable matter.

I'nanother of its important aspects, the invention involves the use-of refined wood pulp as-a source of cellulose in'the preparation of cellulosic solutions for the' viscose process and has for a particular object the use of an unsaponifiable, oil soluble, interfacially active material of'synthetic origin to improve the emulsification or dispersion of non-miscible: opacifying agents in viscose solutions used'in sp'inning filaments, particularly as regards stabilizing emulsions produced in the. presencevof anion-active emulsifying materials. The invention also generally brings about improvements in other processing steps and may be used with bright as Welles opacified viscose.

Refined wood pulp consists mainly of cellulose with relatively small amounts of non-cellulosic impurities, such as hemi-celluloses, fats, resins, waxes, high molecular weight alcohols, etc. A substantial portion of the non-cellulosic impurities is extractable with ether, and is hereinafter called the etherextract 01' the ether extractable matter.

I- have found that the: ether two distinctly different types of materials which possess or can exert under appropriate conditions interfacially active properties and which have important effects on the processing qualities of the pulp in the production of cellul'osic products. These two classes are:

1. Ihe saponifiable' portion of the ether: extract (otherwise termed ether extractable saponifiable matter) which is of the-nature of fatty andresin' acids either in the'free state or combined in such extract contains forms as glycerides or esters of higher alcohols. These materials in their saponified state are water soluble soaps, i. e., are anion active agents. (-Where numerical valuesfor saponifiable matter are herein given, such values refer to the total amount of fatty and resin acids, both in free and combined form.)

2. Another portion consisting of unsaponifiable materials which are substantially nonvolatile; insoluble in water and dilute caustic soda, soluble in oil; and interfacially active at an oil-water interface. These unsaponifiable,-. oil soluble,. interfacially active materials are in general. high molecular weight alcohols such as. phytosterol. (Phytosterol is the-genericname forsterols derived from vegetable sources.)

Part of thephytcsterol isintheform of saponifiable esters withhigher fatty acids. On saponifloat-ion these esters form soaps and liberate-free phytosterol. The phytosterol. itself? is, however, unsaponifiablewhether inf-rec or combined form. Furthermore, in this connection in. referring to the unsaponifiable portion. of the ether extract (otherwise termed ether extractable unsaponi fiable. matter) thereis-meant'all the water insoluble residue which in asaponification treatment does not-combine with caustic alkalies to form water soluble soaps, irrespective as. to whether such material is in f-ree. or combined form inthe ether extract.-

As commonlyused and as referred to specifically herein, the. terms interfacially active. applied toamaterialrefersto the material beingcapable of lowering the interfacial tension at an interfaceby virtue of a positiveadsorption therein. The term surfaceactive material refers to a water soluble material which will specifically reduce the interfacial tension at an air-water interface, such. a liquid-air interfacial tension being commonly termed; the surface tension. By the termanion active material ismeant a water soluble, ionizable surface active material; the surface activity of. which is cluev to the anion; Such materialsmay be presentin the pulp'inan actually anion active form, or ina forum which is converted to a soap. by the action of alkali.

Naturally occurring unsaponifiable; oil soluble; interfacially active-agents constitute alargefraction of the unsaponifiable The: unsaponifiablet ether. extractable matter also containsother: fractions such: as hydrocarbons and: chlorinated hydrocarbonswhich are not interfaciall y active. Nevertheless the: amount. of total unsaponifi'able ether extractable matter serves generally as a relative indication of the amount of unsaponifiable, oil soluble, interfacially active material and is a more easily determined value.

I have found that as regards difierent woods commonly used for producing pulp, such as pine, spruce, and hemlock, the ether. extract left in the refined pulp varies appreciably in the content of unsaponifiable matter, and thus also as regards the proportions of oil soluble, unsaponifiable, interiacially active material and of saponifiable matter which will be interfacially active in the water soluble, saponified state. A comparison of the compositions of ether extracts from refined pulps prepared from different woods and having the same total amounts of ether extract follows:

TABLE I Comparison of composition of ether extracts of refined chemical pulp prepared from difierent woods Percent of Material Present Based on Bone Dry Pulp Such figures as given above are also somewhat dependent on the process by which the pulp is made.

The two classes of extractable materials which are interfacially active or which can become interiacially active have different physical and chemical properties and exercise different effects in the subsequent utilization of the pulp, as in its conversion into various cellulosic products in the chemical and rayon industries. Some of these effects are desirable while others are not, but uniformity of effect is very desirable.

I have discovered that the behavior of the refined wood pulp in its conversion into various cellulosic products cannot be predicted on a basis of the amount of residual ether extract considered as a whole. I have found, for example, that hemlock and southern pine pulps each having the same quantity of ether extract, say 0.15%, have the same properties because the hemlock pulp will contain a higher proportion of ether extractable, unsaponifiable matter. The hemlock pulp thus contains a higher proportion of oil soluble, unsaponifiable, interfacially active materials and a lower proportion of saponifiable matter, interfacially active in the water soluble, saponified state.

It is accordingly one of the objects of my invention to provide a refined wood pulp containing uniform quantities of either saponifiable matter, interfacially active when saponified, or unsaponifiable interfacially active ether extractable matter, or both, regardless of the kind of wood from which the pulp was produced.

In accordance with the method of my invention, I attain uniformity of pulp composition with respect to ether extract by ascertaining the kinds and proportions thereof in the pulp and then adding the required amount of synthetic, oil soluble, unsaponifiable, interfacially active materials of a type not found in nature or saponifiable fatty or resin acid soap-forming materials (either as such or as their effective equivalents in the form of saponified soaps), to

do not 7 produce a pulp with a uniform amount of either one or both together as required.

In practice the invention is applied to wood pulp containing not over 0.15% of natural ether extractable matter consisting of saponifiable and not over 0.07% of oil soluble, unsaponifiable matter. The adjustment of saponifiable and unsaponifiable matter to predetermined value is carried out such that the total amount of unsaponifiable matter, both natural and synthetic does not exceed 0.07%.

The unsaponifiable, oil soluble compounds used as additives in my invention are in general ethylene glycol monoethers of high molecular weight alcohols. These agents, described later in detail, are purely synthetic and do not occur at all as natural constituents of pulp ether extracts.

The synthetic, unsaponifiable compounds are extremely eifective in regard to their interracially active properties. The compounds are in general relatively inexpensive as compared with natural, unsaponifiable, oil soluble, interfacially active materials. Furthermore, as synthetic compounds, the compounds of the invention have the advantage of being readily producible in a pure and uniform state.

The refined wood pulps applicable to use in the invention, such as the so-called dissolving pulps, usually contain less than 0.07% of unsaponifiable ether extractable matter. The invention, however, is especially and advantageously applicable to those pulps containing a relatively low percentage of unsaponifiable ether extractable matter, say less than 0.02%, wherein substantial additions of the synthetic oil soluble, un-

saponifiable compounds are necessary to attain a uniform content of said matter, not greater than 0.07%, in all species of refined wood pulp.

As heretofore pointed out, the amount 0;" unsaponifiable ether extractable matter has been chosen as a standard rather than the exact amount of unsaponifiable, ether extractable, interfacially active matter in that the former serves as a relative indication of the amount of the latter and may be much more readily determined.

While it will be readily obvious to anyone skilled in the art how to determine ether extractable unsaponifiable matter, nevertheless for clarity, I give the standard procedure which follows: 350 gm. of pulp of known moisture content, usually about l-8% moisture, is extracted 8 hours with ether in a Soxhlet extractor. The ether is evaporated oh the extract solution and the residue may be weigh-ed if desired to determine the total amount of ether extractable matter. The residue from the ether evaporation is then refluxed with cc. normal alcoholic KOl-i for 1 hour. The solution is then transferred to a separatory funnel, an equal quantity of water added and the unsaponifiable matter extracted with ether. The ether solution is washed with water, dried by addition of anhydrous NaZSOA, after which the solution is filtered, the sodium sulfate being discarded after being washed with other. The ether is evaporated off and the residue heated 1 hour at C., then cooled and weighed. The value for other extractable unsaponifiable matter so obtained is then calculated the per cent on bone dry pulp.

Wood pulp as usually prepared as a source of cellulose for the viscose industry 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 an appreciable amount of non-cellulosic impurities, such as hemi-celluloses, fats, resins, waxes, etc. One of themain'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 prcducinga higher grade yarn.

As described in U. S. Patent Re. 22,489, not all of the non-cellulosic impurities which can be removed are undesirable from the standpoint of viscose processing, and in fact certain of such impurities, normally present in small amounts, act beneficially as emulsifying agents in the step of emulsifying or dispersing oils or pigments in the viscose. These beneficial impurities which have been known to act as emulsifying agents are surface active 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 whichhas not been highly refined most of these beneficial impurities constitute a portionof the materials removed by organic. solvents, as for example, ether, benzene, alcohol, etc. These impurities which actas anion active emulsifying agents are of the nature of fats, oils, fatty acids, rosin and resin acids, all of which become incorporated in the viscose as sodium soaps.

In theory, the problem of making a good pulp for viscose processing could be solved by removing all the undesirable impurities while retaining in suitable amounts those impurities which facilitate the steps of emulsification and other processing steps. Under such theoretical conditions, the impurities which it would be desired to retain in suitable amounts from the standpoint of emulsifioation would be of two quite different types:

1. The natural oils, fats and fatty acids, rosin and resin acids, which in the viscose process form soaps. Such soaps in addition to improving the processing of the pulp into viscose, also due to their presence in the .viscose, act as emulsifying agents.

2. The natural interfacially active materials soluble in oil and insoluble in water heretofore described in detail. These materials function as stabilizers of emulsions produced by the acid of anion active agents.

In practice such a clean-cut separation is difficult to accomplish directly. Better results are obtainable by removing most or all of the impurities, including the unsaponifiable ether extractable matter, and then incorporating in the viscose small amounts of the synthetic unsaponifiable compounds of the invention. Where the content of natural soap-forming, emulsifying materials is low, anion active materials may also be added in accordance with Patent Re. 22,489.

In refined wood pulps, the unsaponifiable portion of the ether extractable matter will generally fall below 0.07%. While my invention is applicable to use in cellulosic solutions prepared from refined wood pulp containing not more than 0.07% ether extractable unsaponifiable material, the advantages of adding the unsaponifiable, oil soluble, interfacially active material according to the invention are especially great when the pulp contains less than 0.02% unsaponifiable material.

In accordance with this phase of the invention, a small quantity of the synthetic unsaponifiable compound of the invention is incorporated in the cellulosic material used in producing a viscose solution,,at least prior to. completion .of shredding phases.

a scum to separate.

the alkali cellulose, and preferably to "the pulp prior-to use, to improvethe characteristics of the spinning solution, particularly with regard to emulsification with opacifying agents.

Since the synthetic unsaponifiable, oil soluble, interfacially active materials are insoluble in water or dilute caustic sodathey become dispersed in a finely divided conditioniin the viscose. 'Since the materials are oil soluble, they are thus in part extracted from suspension in the aqueous viscose phase by means of the oil dropletsduring the emulsification process. .In order for this extraction process to take place an efficient degree, it is not only necessaryfor the materialsto be oil soluble but also thattheybe substantially water insoluble.

The synthetic unsaponifiable compounds which I add in practicing my invention, like conventional surface active materials, are hydrophiliclipophilic combinations. These compoundshave a strong lipophilic group of. a hydrocarbon-character, together with a groupfhaving a relatively weak hydrophilic effect. Thus, the interfacially active unsaponifiablecompounds used in my invention are at least slightly oil soluble but substantially water insoluble. While the hydrophilic effect is not enough for the compounds to be appreciably soluble in water, there is nevertheless a substantial attraction for water. Hence the compounds will tend .to concentrate wherever there is an oil-water interface with the lipophilic portion dissolved in the water.

The compounds used inmy invention do not greatly lower the surface tensions of any oils they dissolve in. Being substantially insoluble in water or aqueous solutions, they do not appreciably lower the'surface tension of aqueous Nevertheless, when present at an oilwater interface they produce very low interfacial tensions.

In general, the unsaponifiable materials or compounds are ethylene glycol monoethe'rs of high molecular weight alcohols, i. e., of alcohols containing at least 8 carbon atoms. The alcohols are hydroxyl substituted hydrocarbons and may be aliphatic (straight or branched chain, saturated or unsaturated) or cyclic. They may be primary, secondary, or tertiary. I prefer to use high molecular weight aliphatic alcohols (branched chain or straight) containing 8-4-8 carbon atoms. The ethylene glycol monoethers may be prepared me manner similar to that generally employed in manufacturing lowermolecu- 1.2)1' weight glycol monoethers such as are used in solvents (e. g., the methyl, ethyl or butyl monoether of ethylene glycol). Thus, for example, an alcohol containing at least eight carbon atoms may be reacted with an equivalent amount of ethylene oxide to give aproduct predominating in the monoalkyl ether of ethylene glycol.

The following unsaponifiable, oil soluble, interfacially active compounds are examples of compounds which may be used in the practice of my invention:

Ethylene glycol monoether of octyl alcohol (2- ethylhexanol) Ethylene glycol monoether of vtetradecyl alcohol (7 -ethyl-2-methylundecanol-4) Ethylene glycol monoether of oleyl alcohol.

When viscose is emulsified with mineral oil, even if the oil particles are relatively fine, if the emulsions. are not completely stable, there will be a tendency for the emulsions tocream or for -In,the viscose industry such scums ,are extremely tr.o ublesome ;in that they tend to collect in various lines and tanks and may or by means of a rotating roll partly immersed work into the spinnerets where they will cause in such an emulsion or dispersion. If desired, inferior or spoiled yarn. I have found that such the unsaponifiable, oil soluble, interfacially acscums tend to occur when the amount of ether tive compounds may be incorporated in the pulp extractable unsaponifiable material in the pulp prior to sheet formation as, for example, by is low, i. e., when such material is below 0.07% making additions to a suspension of pulp in and especially when in the range of 0 to 0.02%. water in a stock chest. In such cases the scum will still be obtained even The application of the unsaponifiable matewhen anion active emulsifying agents are added rials or compounds to the pulp may be accomto aid the emulsifying step. plished by use of a solution of the compound A convenient laboratory test indicative of the in a satisfactory organic solvent but more pracrelative amounts of scum obtainable in comtically, from an economical standpoint, by use mercial operations with oil-opacified viscose from of an aqueous emulsion as described above. The different pulp samples follows: 800 gm. of viscose preparation of such an aqueous emulsion may is emulsified for 5 minutes with 0.4% mineral oil 5 be eifected by any appropriate procedure combased on viscose using a small bladed paddle remon to the art, generally in the presence of volving at 4000 R. P. M. Portions of the freshly a small amount of a water soluble emulsifying emulsified viscose samples are then centrifuged agent. for 1 hour at a force of 1500 x gravity. The For application during the shredding operation, amounts of scum which may separate out as the compounds may be sprayed directly onto layers on the tops of tubes from various viscose the alkali cellulose as a concentrated solution samples are compared. in a suitable organic solvent, preferably a water When the unsaponifiable material is added miscible, volatile solvent such as ethyl alcohol according to the invention to pulps that would or isopropanol. They may also be sprayed into normally give scum in the above test, scum is the shredder as a concentrated emulsion or liqeither completely eliminated or greatly reduced. uid compounds may be employed in undiluted In addition microscopic examinations show that form. the addition of the unsaponifiable material Where the total ether extractable content of greatly improves the emulsion characteristics, the pulp is very low, in addition to adding the imparting greater stability of particle size, greater unsaponifiable compounds of the invention, uniformity and smaller average particle size. there may also be added according to Patent That scum formation is due to a lack of natural Re. 22,489 fatty or resin acid soap-forming maunsaponifiable ether extractable material may be terials or their effective equivalents in the form seen from the following table. The table also of the anion active, water soluble saponified shows the remarkable effect on reduction of scum soaps. Also other anion active agents may be by addition of a small amount of the ethylene glyadded according to Patent Re. 22,489. When col monoether of '7-ethyl-2-methylundecanol-4. such materials are added in a water soluble,

TABLE II Effect on scum in viscose emulsions of unsaponifiable portions of pulp ether extractable matter and of an oil soluble, ethylene glycol mcnoether of an aliphatic alcohol (ethylene glycol monoether of 7 -ethyl-2-methyZuncZecano1-4) Amount and Source of Amount and Source of Pulp Used Unsaponifiable Ether- Saponifiable Ether Amount of Scum Obtained in Scum Cen- Extractable Material Extractable Material I trifuge Test #1 Pulp 0.034% Natural..- 0.057% Natural Trace of Scum.

#2 Pulp 0.013% Natural... 0.065% Natural... Heavy Scum.

#2 Pulp lrnpreg. with 0.05% of Unsaponifiable Ether 1311- {0.034% Natural.-. 0650/ Natural Very Small Trace of tractable Material from #1 Pulp. +0.05% from #1 Pulp j Scum.

#2 Pulp Impreg. with 0.05% of Saponifiable Ether Extract- 0 0137 Natural {0.065% Natural }Heavy Scum, addition able Material from #1 Pulp. 0 0.05% from #1 Pulp having no eifect.

#3 Pulp, being of the same manufactured type as #2 Pulp.-... 0.005% Natural... 0.025% Natural. Heavy Scum.

#3 Pulp Impreg. with 0.027 ethylene glycol monether of 7- {00057 Natural...

ethyl2-mcthylundccanol i. 0,02% 301511101 1 l The oil soluble ethylene glycol monoethers of anion active condition, it will frequently be con- No Scum.

aliphatic alcohols may be incorporated in the venient to emulsify the unsaponifiable, oil solufinished wood pulp, or during the formation of ble, interfacially active materials in a solution the pulp sheet or during the viscose processing, of the anion active compound. Of the anion prior to the completion of shredding. Since active or potentially anion active compounds, the materials are not soluble in water, it is not the most suitable are the saponifiable soappractical to add them directly to the viscose. forming materials (fatty or resin acid materials) Such direct addition gives an unsatisfactory disor their efiective equivalents in the form of the tribution of the material in the viscose so that saponified soaps.

if the viscose is subsequently emulsified, the With highly refined pulp, as the ether extractemulsion will not be satisfactorily stabilized. able material approaches zero, if only the un- A most practical and convenient method of sesaponifiable, oil soluble, interfacially active comcuring the presence of the desired amount of pounds are added without anion active comunsaponifiable material in the viscose in a satpounds, some improvements are obtained but the isfactorily fine state of subdivision is to incoradvantages of the invention are obtained only porate the compound in the wood pulp. Such in part.

an addition may be advantageously effected to In the preferred form of the invention, in addithe pulp on the sheet forming machine subtion to the glycol ethers of aliphatic alcohols, sequent to sheet formation but prior to complete anion active compounds will be present, either drying by spraying the pulp sheet with an through their presence in natural form in the aqueous emulsion or dispersion of the compound ether extractable material or by addition.

While the synthetic unsaponifiable, oil soluble, glycol monoethers used in this invention are especially suitable for use in combination with anion active or potentially anion active compounds, they are also suitable for use in combination with cation active compounds, nonionic surface active compounds and mixtures of these.

Since the amount of unsaponifiable ether extractable matter varies widely in pulps from different woods, the invention makes it possible to impart to pulp from one wood many of the processing characteristics of pulp from a different wood. In this way, I can produce a uniform refined wood pulp; in other words, an industrially uniform composite irrespective of the many different kinds of Woods from which it originates.

While scum formation is not normally encountered in bright (nondelustered) viscose, use of pulp treated with an unsaponifiable compound in the manner of the invention is, however, also advantageous in the preparation of bright viscose. Such treatment minimizes foaming and occlusion of air in'the viscose during the various mixing operations. Treatment of the pulp with the glycol ethers of aliphatic alcohols of the invention is especially desirable when treating the pulp according to Patent Re. 22,489 with soaps which tend to promote foaming of the viscose. Thus, for example, the unsaponifiable compound can be emulsified in sodium oleate solution and the emulsion used to treat the pulp sheet either on the dryer of the pulp machine or in a sub sequent operation.

When viscose is emulsified with oil for the preparation of delustered rayon, the oil constitutes only a very small portion of the delustered material. Accordingly, since the unsaponifiable compounds dissolve in the oil rather than in the aqueous phase only extremely small quantities of them are required, the effective range of the unsaponifiable compounds being such as to give a total content of unsaponifiable matter, including both natural ether soluble and the synthetic glycol ethers of from 0.01 to 0.07% and preferably from 0.02 to 0.05%. Since the unsaponifiable materials or compounds are not truly soluble in the viscose but rather disperse, with more than 0.07% of such materials, some material may tend to separate out in the viscose, particularly with bright viscose. Accordingly, it is important that the compounds be added only in extremely small amounts as specified. The percentages used herein are based on the bone dry weight of the pulp.

This application is a continuationin-part of my application Serial Number 601,063, filed June 22, 1945, U. S. Patent 2,518,680 and my application Serial Number 631,223 filed November 27, 1945, U. 5. Patent 2,516,113.

I claim:

1. The method of improving refined wood pulp containing not over 0.15% of natural ether-extractable matter, of which less than 0.07% is oil-soluble unsaponifiable matter, which comprises adding to such refined wood pulp an ethylene glycol monoether of an aliphatic hydroxyl-substituted hydrocarbon having from 3 to 18 carbons atoms, the amount of the added monoether of the substituted hydrocarbon being such as not to cause said oil-soluble, unsaponifiable matter to exceed about 0.07%, based on the bone dry weight of the pulp.

2. The method of claim 1 in which the amount 10 of the added monoether of the substituted hydrocarbon is such as not to cause the ether-extractable matter in the pulp to substantially exceed 0.15%, based on the bone dry Weight of the pulp.

3. The method of claim 1 in which the monoether of the substituted hydrocarbon is ethylene glycol monoether of 7 ethyl 2 methyl undecanol-4.

.4. The method of claim 1 in which the monoether of the substituted hydrocarbon is ethylene glycol monoether of oleyl alcohol.

5. The method of claim 1 in which the monoether of the substituted hydrocarbon is ethylene glycol monoether of 2-ethy1 hexanol.

6. The method of improving refined wood pulp containing not over 0.15% of natural ether-extractable matter, of which less than 0.07% is oilsoluble unsaponifiable matter, which comprises adding to such refined wood pulp an ethylene glycol monoether of an aliphatic hydroXyl-substituted hydrocarbon having from 8 to 18 carbon atoms, and at least one compound of the group consisting of soap-forming fatty acids, soapforming resin acids, and the water-soluble sodium salts of said acids, the amount of the monoether of the substituted hydrocarbon being such as not to cause said oil-soluble unsaponifiable matter to exceed about 0.07% based on the bone dry weight of the pulp, and the amount of the monoether of the substituted hydrocarbon and the member of said group added being such as not to cause the ether-extractable matter in the pulp to substantially exceed 0.15%, based on the bone dry weight of the pulp.

7. In the production of cellulosic products having an opacifying agent incorporated therein from wood pulp having not over 0.15% of natural ether-extractable matter, both saponifiable and unsaponifiable, of which less than 0.07% is oilsoluble unsaponifiable matter; the improvement which comprises adding to the wood pulp an ethylene glycol monoether of an aliphatic hydroxyl-substituted hydrocarbon having from 8 to 18 carbon atoms, the amount of such monoether of the substituted hydrocarbon being such that the total amount of ether-extractable, unsaponifiable matter in the wood pulp does not exceed about 0.07 based on the bone dry weight of the wood pulp, whereby in the subsequent processing of the pulp into the cellulosic product, said opacifying agent is dispersed in the cellulosic product without objectionable scum formation.

8. In the production of cellulosic products as defined in claim 7 in which the monoether of the substituted hydrocarbon is ethylene glycol monoether of 7-ethyl-2-methyl-undecanol-4.

9. In the production of cellulosic products as defined in claim 7 in which the monoether of the substituted hydrocarbon is ethylene glycol monoether of oleyl alcohol.

10. In the production of cellulosic products as defined in claim 7 in which the monoether of the substituted hydrocarbon is ethylene glycol monoether of 2-ethyl hexanol.

11. In the production of cellulosic products having an opacifying agent incorporated therein from wood pulp having not over 0.15% of natural ether-extractable matter, both saponifiable and unsaponifiable, of which less than 0.07% is unsaponifiable matter; the improvement which comprises adding to the wood pulp an ethylene glycol monoether of an aliphatic hydroxyl-substituted hydrocarbon having from 8 to 18 carbon atoms and at least one compound from the group consisting of soap-forming fatty acids, soap-forming resin acids, and the water-soluble sodium salts of said acids, the amount of the monoether of the substituted hydrocarbon being such as the total amount of ether-extractable unsaponifiable matter in the pulp does not exceed about 0.07% based on the bone dry weight of the wood pulp and the total amount of the monoether of the substituted hydrocarbon and the member of said group added to the pulp being such that the total amount of ether-extractable matter in the pulp does not substantially exceed 0.15% based on the bone dry weight of the wood pulp, whereby in the subsequent processing into the cellulosic product, said opacifying agent is dispersed in the cellulosic product without objectionable scum formation.

12. A refined wood pulp containing natural and added ether-extractable saponifiable matter and ether-extractable oil-soluble unsaponifiable matter totaling not substantially over 0.15% based on the bone dry weight of the wood pulp, the added ether-extractable oil-soluble unsaponifiable matter being an ethylene glycol monoether of an aliphatic hydroxyl-substituted hydrocarbon having from 8 to 18 carbons atoms, the total amount of ether-extractable oil-soluble unsaponifiable matter in the pulp not substan- 12 tiall exceeding 0.07% based on the bone dry weight of the pulp, said pulp also containing at least one added compound from the group consisting of soap-forming fatty acids, soap-forming resin acids and the water-soluble sodium salts of said acids.

13. A refined wood pulp as defined in claim 12 in which the monoether of the substituted hydrocarbon added to the wood pulp is a com pound selected from the group consisting of ethylene glycol monoether of 7-ethy1-2-methylundecanoli, ethylene glycol monoether of oleyl alcohol, and ethylene glycol monoether of Z-ethyl hexanol.

14. A refined wood pulp as defined in claim 12 in which the added ether-extractable saponifiable matter is a compound from the group consisting of soap-forming fatty acids, soap-forming resin acids and the water-soluble sodium salts of said acids.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 2,423,469 Schlosser et a1. July 8, 1947 2,432,129 Schlosser et a1. Dec. 9, 1947 2,451,558 Schlosser et al Oct. 19, 1948 2,491,499 Katzen Dec, 20, 1949 2,518,680 Gray Aug. 15, 1950

Claims (1)

12. A REFINED WOOD PULP CONTAINING NATURAL AND ADDED ETHER-EXTRACTABLE SAPONIFIABLE MATTER AND ETHER-EXTRACTABLE OIL-SOLUBLE UNSAPONIFIABLE MATTER TOTALING NOT SUBSTANTIALLY OVER 0.15% BASED ON THE BONE DRY WEIGHT OF THE WOOD PULP, THE ADDED ETHER-EXTRACTABLE OIL-SOLUBLE UNSAPONIFIABLE MATTER BEING AN ETHYLENE GLYCOL MONOETHER OF AN ALIPHATIC HYDROXYL-SUBSTITUTED HYDROCARBON HAVING FROM 8 TO 18 CARBON ATOMS, THE TOTAL AMOUNT OF ETHER-EXTRACTABLE OIL-SOLUBLE UNSAPONIFIABLE MATTER IN THE PULP NOT SUBSTANTIALLY EXCEEDING 0.07% BASED ON THE BONE DRY WEIGHT OF THE PULP, SAID PULP ALSO CONTAINING AT LEAST ONE ADDED COMPOUND FROM THE GROUP CONSISTING OF SOAP-FORMING FATTY ACIDS, SOAP-FORMING RESINS AND THE WATER-SOLUBLE SODIUM SALTS OF SAID ACID.